Nichia Corporation v Arrow Electronics Australia Pty Ltd (No 4)

[2017] FCA 864

FEDERAL COURT OF AUSTRALIA

Nichia Corporation v Arrow Electronics Australia Pty Ltd (No 4) [2017] FCA 864

File number:

NSD 558 of 2014

Judge:

YATES J

Date of judgment:

2 August 2017

Catchwords:

PATENTS – standard patent for light emitting device and display device – claim for infringement – cross-claim seeking revocation of certain claims – whether infringement established

PATENTS – validity – obviousness – identity of the person skilled in the art – whether invention was art-changing – availability of prior art information under s 7(3) of the Patents Act 1990 (Cth) – whether invention obvious

PATENTS – validity – manner of manufacture – whether threshold requirement of s 18(1) of the Patents Act 1990 (Cth) met

PATENTS – validity – whether lack of novelty established on the evidence – whether prior art documents relied on were fabricated

PATENTS – validity – whether invention defined – whether definition lacks clarity

Legislation:

Evidence Act 1995 (Cth) ss 57, 63, 64, 136

Patents Act 1990 (Cth) ss 138, 7, 18

Cases cited:

Advanced Building Systems Pty Limited v Ramset Fasteners (Aust) Pty Limited (1998) 194 CLR 171; [1998] HCA 19

Aktiebolaget Hässle v Alphapharm Pty Limited (2002) CLR 411; [2002] HCA 59

AstraZeneca AB v Apotex Pty Ltd (2015) 323 ALR 605; [2015] HCA 30

AstraZeneca AB v Apotex Pty Ltd (2014) 226 FCR 324; [2014] FCAFC 99

Bitech Engineering v Garth Living Pty Ltd (2010) 86 IPR 468; [2010] FCAFC 75

Bristol-Myers Squibb Company v FH Faulding & Company Ltd (2000) 97 FCR 524

Catnic Components Ltd v Hill & Smith Ltd [1982] RPC 183

Commissioner of Patents v Microcell Limited (1959) 102 CLR 232

Decor Corporation Pty Ltd v Dart Industries Inc (1988) 13 IPR 385

DSI Australia (Holdings) Pty Ltd v Garford Pty Ltd (2013) 100 IPR 19; [2013] FCA 132

Elconnex Pty Limited v Gerrard Industries Pty Limited (1991) 32 FCR 491

Electric & Musical Industries Ltd v Lissen Ltd [1938] 4 All ER 221

Fresenius Medical Care Australia Pty Ltd v Gambro Pty Ltd (2005) 224 ALR 168; [2005] FCAFC 220

General Tire & Rubber Company v Firestone Tyre & Rubber Company Limited [1972] RPC 457

H Lundbeck A/S v Alphapharm Pty Ltd (2009) 177 FCR 151

International Business Machines Corporation v Smith, Commissioner of Patents (1992) AIPC 90-853

Lockwood Security Products Pty Ltd v Doric Products Pty Ltd (No 2) (2007) 235 CLR 173; [2007] HCA 21

Nichia Corporation v Arrow Electronics Australia Pty Ltd [2015] FCA 699

Nichia Corporation v Arrow Electronics Australia Pty Ltd (No 3) (2016) 240 FCR 13; [2016] FCA 466

NV Philips Gloeilampenfabrieken v Mirabella International Pty Limited (1995) 183 CLR 655

NV Philips Gloeilampenfabrieken v Mirabella International Pty Limited (1993) 44 FCR 239

Olin Mathieson Chemical Corporation v Biorex Laboratories Ltd [1970] RPC 157

Otsuka Pharmaceutical Co Ltd v Generic Health Pty Ltd (No 4) (2015) 113 IPR 191; [2015] FCA 634

Saint-Gobain PAM SA v Fusion Provida Limited, Electrosteel Casting Limited [2005] EWCA Civ 177

Schlumberger Holdings Ltd v Electromagnetic Geoservices AS [2010] RPC 33; [2010] EWCA Civ 819

Seafood Innovations Pty Ltd v Richard Bass Pty Ltd (2011) 92 IPR 1; [2011] FCAFC 83

The Wenham Gas Company v The Champion Gas Lamp Company (1891) 9 RPC

Tickner v Honda Motor Co Ltd [2002] EWHC 8

Welch Perrin & Co Pty Ltd v Worrel (1961) 106 CLR 588

Wellcome Foundation Limited v V.R. Laboratories (Aust.) Proprietary Limited (1981) 148 CLR 262

Date of hearing:

9 – 17 May 2016

Date of last submissions:

25 May 2016

Registry:

New South Wales

Division:

General Division

National Practice Area:

Intellectual Property

Sub-area:

Patents and associated Statutes

Category:

Catchwords

Number of paragraphs:

445

Counsel for the Applicant:

Mr D Catterns QC with Ms C Cochrane and Mr D Larish

Solicitor for the Applicant:

Allens

Counsel for the Respondent:

Ms K J Howard SC with Mr H P T Bevan

Solicitor for the Respondent:

King & Wood Mallesons

ORDERS

NSD 558 of 2014

BETWEEN:

NICHIA CORPORATION

Applicant

AND:

ARROW ELECTRONICS AUSTRALIA PTY LTD
ACN 065 151 626

Respondent

AND BETWEEN:

ARROW ELECTRONICS AUSTRALIA PTY LTD
ACN 065 151 626

Cross-Claimant

AND:

NICHIA CORPORATION

Cross-Respondent

JUDGE:	YATES J
DATE OF ORDER:	2 AUGUST 2017

THE COURT ORDERS THAT:

1.Each party provide a draft of the orders it proposes (including on costs) to give effect to the reasons published today as Nichia Corporation v Arrow Electronics Australia Pty Ltd (No 4) [2017] FCA 864.   

2.The applicant provide its draft orders to the Associate to Yates J by 4.00 pm on 14 August 2017. 

3.The respondent provide its draft to the Associate to Yates J by 4.00 pm on 21 August 2017.

4.Leave be granted to each party, when submitting their proposed orders, to make supporting submissions in writing, limited to three pages.

Note:   Entry of orders is dealt with in Rule 39.32 of the Federal Court Rules 2011.

REASONS FOR JUDGMENT

INTRODUCTION	[1]
THE WITNESSES	[8]
SCIENTIFIC BACKGROUND	[32]
THE SPECIFICATION	[36]
AN ISSUE OF CONSTRUCTION:  INFRINGEMENT	[67]
The issue	[67]
Conclusion and reasons	[79]
Claim 1	[111]
THE DEVELOPMENT OF THE INVENTION	[116]
Background	[116]
The development of a white LED	[123]
THE PERSON SKILLED IN THE ART	[150]
THE COMMON GENERAL KNOWLEDGE	[169]
The issue	[169]
Conclusion and reasons	[178]
THE EVIDENCE OF THE EXPERT WITNESSES	[189]
Dr Butcher	[189]
Professor Meijerink	[196]
Dr Bretschneider	[216]
OBVIOUSNESS:  THE RESPONDENT’S PRIMARY CASE	[237]
The respondent’s submissions	[237]
The applicant’s submissions	[256]
Conclusion and reasons	[268]
OBVIOUSNESS:  THE PRIOR ART DOCUMENTS	[293]
Introduction	[293]
Blasse and Bril I	[295]
Blasse and Bril II	[298]
The Blasse extract	[300]
Holloway and Kestigian I	[313]
Holloway and Kestigian II	[314]
Hoffman	[316]
The 283 patent	[321]
The 478 patent	[324]
THE APPLICATION OF S 7(3)	[325]
Introduction	[325]
The evidence	[328]
Blasse and Bril I	[333]
Blasse and Bril II	[338]
The Blasse extract	[342]
Holloway and Kestigian I	[346]
Holloway and Kestigian II	[351]
Hoffman	[355]
The 283 patent	[359]
The 478 patent	[366]
Conclusion and reasons	[371]
OBVIOUSNESS:  SECONDARY INDICIA	[380]
MANNER OF MANUFACTURE	[382]
LACK OF NOVELTY	[396]
Introduction	[396]
The evidence of public availability	[400]
Document 1	[400]
Document 2	[410]
Dr Kramer’s evidence	[421]
The respondent’s submissions	[430]
Conclusion and reasons	[431]
S 40 MATTERS: LACK OF FAIR BASIS, DEFINITION AND CLARITY	[442]
CONCLUSION AND DISPOSITION	[445]

YATES J:

INTRODUCTION

1. The applicant, Nichia Corporation, is the patentee of Patent No. 720234 (the patent).  It sues the respondent, Arrow Electronics Australia Pty Ltd, for infringement of claim 3 of the patent.  Claim 3 is dependent on claim 1.

2. Claim 1 is:

   A light emitting device, including a light emitting component and a phosphor capable of absorbing a part of light emitted by the light emitting component and emitting light of wavelength different from that of the absorbed light; wherein said light emitting component comprises a nitride compound semiconductor and said phosphor contains a garnet fluorescent material including at least one element selected from the group consisting of Y, Lu, Sc, La, Gd and Sm, and at least one element selected from the group consisting of Al, Ga and In, and being activated with cerium. 

3. Claim 3 is:

   A light emitting device according to claim 1, wherein the phosphor contains fluorescent material represented by a general formula (Re_l-rSm_r)₃(Al_1-sGa_s)₅O₁₂:Ce, where 0≤r<l and 0≤s≤1 and Re is at least one selected from Y and Gd. 

4. The respondent denies infringement and has cross-claimed seeking revocation of claims 1 and 3 under s 138(1) of the Patents Act 1990 (Cth) (the Act) on the grounds that, at the priority date:

   ·the invention, as claimed in each claim, was not novel;

   ·the invention, as claimed in each claim, was obvious and did not involve an inventive step;

   ·the invention, as claimed in each claim, was not a manner of manufacture within the meaning of section 6 of the Statute of Monopolies;

   ·the invention, as claimed in each claim, was not fairly based on the matter described in the specification; and

   ·the invention, as claimed in each claim, was not defined and was not clear. 

5. The relevant specification (AU 199736355 C) is entitled “Light emitting device and display device” (the specification). 

6. The priority date for each claim is, relevantly, 29 July 1996 (the priority date).  The priority date was determined as a separate question: Nichia Corporation v Arrow Electronics Australia Pty Ltd [2015] FCA 699 (Reasons 1).

7. For the reasons that follow, I have concluded that the applicant’s case on infringement has not been established.  I have also concluded that the respondent’s case on invalidity has not been established.

   THE WITNESSES

8. At the present hearing, the applicant adduced evidence from:

   ·Kenneth Scott Alexander Butcher;

   ·Andries Meijerink;

   ·Genichi Shinomiya; and

   ·Michael Kramer.

9. The respondent adduced evidence from:

   ·Eric Colin Bretschneider;

   ·Kuang-Mao Lu; and

   ·Stefan Richter.

10. Dr Butcher, Professor Meijerink and Dr Bretschneider were called as experts.  They made affidavits and gave concurrent evidence.  Their affidavits were read subject to agreed rulings.  Each deponent was separately cross-examined.  I summarise aspects of their evidence in later paragraphs of these reasons.  Their evidence was directed primarily to the respondent’s case on invalidity, in particular its case on obviousness.  For present purposes, I record the following background matters concerning each expert.

11. Dr Butcher is the President and Chief Scientist of a Canadian corporation, Meaglow Ltd, which he founded in 2009 to develop Migration Enhanced Afterglow (MEAglow) and plasma-based technology for use in the semiconductor industry.  He holds the degrees of Bachelor of Applied Science in Physics (Second Class Honours, Division 1), which was conferred by the University of Technology, Sydney in 1985, and Doctor of Philosophy, which was conferred by Macquarie University in 1997.  His research for his doctoral degree was in the area of nitride compound semiconductors. 

12. Between 1999 and 2005, Dr Butcher was a Research Fellow, and then an Australian Postdoctoral Fellow, in Macquarie University’s Physics Department.  His principal area of research was the growth and characterisation of nitride semiconductors and their fabrication into test devices.  He established Macquarie University’s Low Temperature Nitride Growth Facility.

13. Between 2005 and 2008 he founded a number of start-up companies to commercialise his research into the growth of nitride semiconductors at low temperatures and to develop plasma source systems for nitride film growth.

14. In 2009, he moved to Canada.  Between 2010 and 2014 he was an Adjunct Professor in the Electrical Engineering Department of Lakehead University in Thunder Bay, Ontario, where he is now located.

15. Dr Butcher is the author of more than 100 refereed journal articles and conference papers.  He is named as an inventor or co-inventor in seven international patent applications.

16. Professor Meijerink holds the Chair of Solid State Chemistry in the Department of Chemistry at Utrecht University in the Netherlands.  Amongst his academic qualifications, Professor Meijerink holds the degrees of Master of Science cum laude and Doctor of Philosophy cum laude.  These degrees were conferred on him by Utrecht University in 1986 and 1990, respectively.  As part of the work undertaken for his Master’s degree, Professor Meijerink conducted detailed research on Y₂O₃:Eu³⁺, the red phosphor used in fluorescent tubes.  As part of his doctoral degree, Professor Meijerink conducted research on X-ray storage phosphors used for digital x-ray imaging. 

17. Professor Meijerink has had over 30 years’ experience as a researcher, author, teacher and inventor in the field of luminescence spectroscopy, with a particular focus on phosphor materials.

18. Professor Meijerink has been retained by the applicant in proceedings conducted in the Federal Patent Court in Germany (the FPC).  I have referred to these proceedings in Nichia Corporation v Arrow Electronics Australia Pty Ltd (No 3) (2016) 240 FCR 13; [2016] FCA 466 (Reasons 3), when dealing with the admissibility of certain evidence sought to be adduced by the respondent.  In broad terms, the European patent in the FPC proceeding corresponds to the patent in this proceeding, at least insofar as it claims, amongst other things, an LED containing YAG:Ce, which is capable of emitting white light.

19. Dr Bretschneider is a chemical engineer and the Chief Technical Officer of EB Designs & Technology LLC, which Dr Bretschneider described as a company which specialises in the design and development of innovative solid-state lighting technology.  He holds the degrees of BSE in Chemical Engineering, which was conferred by Tulane University in 1989, and Doctor of Philosophy, which was conferred by the University of Florida in 1997. 

20. Following his graduation from Tulane University, Dr Bretschneider commenced postgraduate research at the University of Florida.  His research investigated the use of ZnSe as a semiconductor for the emission of blue light for use in LEDs.  The research for his doctoral degree was in red light emitting ZnS Si semiconductor structures. 

21. From 1989 to 1996, he trained graduate students and postdoctoral researchers in MOCVD (metal organic chemical vapour deposition) growth systems, and the technology and theory behind those systems.  MOCVD is a method of growing semiconductor layers prior to processing (fabricating) those layers into semiconductor chips. 

22. In 1990, Dr Bretschneider was a visiting researcher at the AT&T Bell Labs Holmdel Complex in New Jersey (AT&T).

23. From around 1993 to 1996, Dr Bretschneider worked on a variety of different projects through the Phosphor Technology Center of Excellence, a consortium between several universities in the United States of America and private enterprise.  These projects included the development of phosphors for plasma televisions and the synthesis of phosphors for electroluminescence research and backlights for liquid-crystal displays.

24. Dr Bretschneider said that his fields of interest before the priority date included the fabrication of new kinds of semiconductor materials and their use as LEDs.

25. Dr Bretschneider has been retained by companies, including Everlight Electronics Co., Ltd (Everlight), to provide expert evidence in proceedings in which those companies were or are parties opposed to the applicant.

26. I should also record that evidence from another expert, Roger John Reeves, was received at the hearing of the separate question.  Professor Reeves is a Professor in the Department of Physics and Astronomy, University of Canterbury, Christchurch, New Zealand.  He made three affidavits (9 April 2015; 14 May 2015 and 10 June 2015).  Certain parts of his first affidavit, and his second and third affidavits, were read at the hearing of the separate question and are referred to at [120]-[127] of Reasons 1.  His evidence was taken as being before me at the present hearing.

27. Mr Shinomiya is the applicant’s Managing Director.  He is also the Deputy Operating Manager of the Development Division of the applicant’s Optoelectronics Business Unit as well as the General Manager of the applicant’s Yokohama Technology Center and Suwa Technology Center.  He made an affidavit concerning the applicant’s development of the white LED.  Mr Shinomiya was cross-examined through an interpreter.

28. Dr Kramer is the Managing Director of LED Linear GmbH, a company located in North Rhine-Westphalia, Germany.  In 2000, he was appointed as the co-Managing Director of Vossloh-Wustlich Opto GmbH & Co. KG (Vossloh-Wustlich) following the acquisition by Vossloh AG (a German manufacturer of lighting components and transport technology) of Wustlich Mikro-Elektronik GmbH (Wustlich Mikro) and Wustlich Opto-Elektronik GmbH (Wustlich Opto).

29. He made an affidavit in which he deposed to certain events related to the proceeding in the FPC to which I have referred including, in particular, a conversation he had with his co-Managing Director, Hans-Dieter Wustlich, concerning certain correspondence which is important to the respondent’s case that claims 1 and 3 of the patent are invalid on the ground that the invention was not novel at the priority date.  I refer to this evidence in greater detail below.  Dr Kramer was cross-examined.  Part of his oral evidence was given with the aid of an interpreter.

30. Mr Lu is a chemical and materials engineer who is employed by Everlight.  Everlight made the products which, it is alleged, the respondent supplied in infringement of claim 3 of the patent.  He made an affidavit in which he identified and described the fluorescent materials present in the products concerned.  Mr Lu was not cross-examined.

31. Dr Richter is an attorney-at-law admitted to practise in Germany.  His firm acts for Everlight in the FPC proceeding and in related appeal proceedings.  He made an affidavit in which he described certain events relating to the FPC proceeding.  Dr Richter was not cross-examined.

    SCIENTIFIC BACKGROUND

32. At [9]-[33] of Reasons 1, I provided a brief scientific background based on a primer that had been prepared by the parties for use in determining the separate question.  The parties have made some amendments to the primer to provide greater precision and clarity, and have added some sections that are pertinent to understanding the scientific issues that arise in determining the remaining questions in the proceeding.  The supplementary primer has been admitted into evidence.  It is reproduced in the Schedule to these reasons.  The parties accept that the amendments to, and additions in, the supplementary primer do not affect the question of the correct priority date that has been determined.  These reasons proceed on an assumed knowledge and understanding of the supplementary primer (the primer).

33. At this point, it is convenient to draw attention to two of the ways in which white light can be characterised. 

34. The first is colour temperature.  The colour temperature of a light source refers to the temperature at which a black-body radiator (see paragraph 69 of the primer) radiates visible light to which the colour of the light source can be compared.  By this measure, white light can be neutral (3,500-4,000 degrees Kelvin (K)), cool-white (a bluish white) (5,000 K or higher), and warm-white (a yellowish white) (2,700-3,000 K).

35. The second is the colour rendering index (CRI).  This is a quantitative measure of the ability of a light source to reveal the colour of an object compared with an ideal, natural light source.  It allows one to say how “natural” colours look when viewed under the light source.  The maximum CRI is 100.  For industrial lighting, a CRI of >60 is usually acceptable; >70 is usually acceptable for street lighting, and >80 is usually acceptable for house lighting.  A CRI of ≥90 is used for specialty applications, such as museum display lighting and medical equipment.

    THE SPECIFICATION

36. The specification discloses that various attempts have been made to make white light sources using light emitting diodes.  It is common to refer to light emitting diodes as LEDs.  I will do so in these reasons, although I note that the specification uses “LED” as the acronym for a “light emitting device”.  The specification uses the expression “light emitting device” to refer to a phosphor in combination with a “light emitting component” where the phosphor of the device converts the wavelength of the light emitted by the light emitting component.  In other parts, the specification appears to use the expression “light emitting device” synonymously with a “light emitting diode”.  I do not think that anything turns on this.  The specification identifies the “light emitting component” of the device as a nitride compound semiconductor.

1. The specification refers to the advantages of LEDs as a light source:  they are compact and emit light of a clear colour with high efficiency; they are free from “burn-out” and have good initial drive characteristics; they have high vibration resistance, and high durability to endure repetitive on/off operations.  The specification explains, however, that, although LEDs are effective as light emitting devices for generating monochromatic light (such as red, green and blue), a satisfactory light source capable of emitting white light using these components has not been obtained.

2. The specification discloses that the applicant had previously developed LEDs which use a fluorescent material to convert the colour of light that is emitted by the light emitting component.  The specification identifies a number of patents held by the applicant which, the specification says, disclose LEDs that are capable of generating white light and other colours.  The specification describes these LEDs as follows:

   The light emitting diode … are made by mounting a light emitting component, having a large energy band gap of light emitting layer, in a cup provided at the tip of a lead frame, and having a fluorescent material that absorbs light emitted by the light emitting component and emits light of a wavelength different from that of the absorbed light (wavelength conversion), contained in a resin mold which covers the light emitting component.

   The light emitting diode disclosed as describe above capable of emitting white light by mixing the light of a plurality of sources can be made by using a light emitting component capable of emitting blue light and molding the light emitting component with a resin including a fluorescent material that absorbs the light emitted by the blue light emitting diode and emits yellowish light.

   (As in original.) 

3. The specification says that these “conventional” LEDs have problems.  These problems centre on the deterioration of the fluorescent material.  The deterioration arises from various causes. 

4. First, there is deterioration of the fluorescent material arising from the amount of light energy the material absorbs from the light emitting component.  The specification discloses that this is a problem with organic phosphors and some inorganic phosphors ((Cd,Zn)S is exemplified). The deterioration of the fluorescent material leads to colour tone deviation of the emitted light.  It also leads to darkening of the material, which results in lowered efficiency in terms of “extracting light”.

5. Secondly, there is deterioration brought about by the high temperature of the LED and heat transmitted from the external environment, such as sunlight when the device is used outdoors. 

6. Thirdly, some fluorescent materials are subject to accelerated deterioration due to a combination of moisture (whether introduced from the outside or during the production process) and the light and heat transmitted from the light emitting component.

7. The specification also teaches that, where the fluorescent material is an organic dye, electrophoresis may result in a change in the colour tone of the emitted light.

8. The specification says that the invention aims to provide an alternative to known light emitting devices and displays, which alleviates at least one of the described problems to provide a light emitting device which experiences only extremely low degrees of deterioration in emission light intensity, light emission efficiency and colour shift over a long time of use, with high luminance.

9. The specification describes one aspect of the invention as a light emitting device that includes a nitride compound semiconductor component in combination with a phosphor that contains a garnet fluorescent material.  The garnet fluorescent material must include certain identified elements.  It is activated with Ce. 

10. I pause to note that it is accepted that the nitride compound semiconductor emits blue light.  The phosphor—the described garnet fluorescent material—is excited by the blue light emitted from the light emitting component, and emits yellow light.  There is no dispute that blue light has a wavelength of approximately 450 nanometres (nm) and that yellow light has a wavelength in the range of approximately 500 to 700 nm.  Thus, in the invention, the wavelength of the light emitted from the phosphor is longer than the wavelength of the light emitted from the light emitting component that is absorbed by the phosphor.  The conversion of light from one wavelength to another is called spectral conversion. 

11. The specification teaches that, generally, a fluorescent material which absorbs light of a short wavelength and emits light of a long wavelength (the specification is here discussing relativities) has higher efficiency than a fluorescent material which absorbs light of a long wavelength and emits light of a short wavelength. 

12. The specification also teaches that it is preferable to use a light emitting component that emits visible light rather than ultraviolet (UV) light, because UV degrades the resin which is used as a moulding or coating material in the housing of the LED, which also includes the phosphor of interest embedded in the resin that coats the light emitting component.  To this end, the specification teaches that it is preferable that the main emission peak of the light emitting component be set within a relatively short wavelength range of 400 nm to 530 nm, in the visible light region.   

13. The blue light and the yellow light emitted by the light emitting component and the phosphor respectively, blend to produce white light.  In its evidence and submissions, the applicant referred to a blue LED combined with fluorescent material to produce a white light source as a white LED.  I will use the same expression.

14. For this embodiment, the specification expresses a preference for a phosphor that is an yttrium-aluminium-garnet fluorescent material (YAG phosphor) activated with Ce.  The fluorescent material having the general formula in claim 3 is specifically referred to amongst other formulae:  see [3] above.  Although the specification uses a number of formulae, I will refer to the formula in claim 3 as the general formula.

15. The specification teaches that the wavelength of the light emitted from the YAG phosphor can be shifted to a shorter wavelength by substituting part of the Al in the phosphor with Ga.  In this connection, the general formula comprehends the possibility of having only Al (and no Ga), or only Ga (and no Al), or a combination of both, in the phosphor. 

16. Further, the general formula requires that the phosphor also include Y or Gd, or both.  Sm can be present with the Y and/or Gd, but not alone.  The specification teaches that the wavelength of the light emitted from the YAG phosphor can be shifted to a longer wavelength by substituting part of the Y in the phosphor with Gd.

17. Thus, the light colour emission can be changed continuously by changing the composition in the ways described immediately above.  The specification also teaches that the addition of Sm will improve the efficiency of the light emission.

18. A second aspect of the invention is described in which a nitride compound semiconductor (represented by a given formula) is used in combination with a phosphor that contains one, two or more garnet fluorescent materials according to the general formula subject to the additional requirement that r≠0.

19. A third aspect of the invention is described in which a nitride compound semiconductor (represented by a given formula) is used in combination with a first fluorescent material (represented by a given formula) and a second fluorescent material (represented by another given formula).

20. A fourth aspect of the invention is described.  It is a method of preparing a white light emitting device.

21. The following matters should be noted.

22. First, so far as fluorescent materials are concerned, the invention described in the specification is directed to the use of garnet fluorescent materials of a particular kind.  Attention is directed to Y₃Al₅O₁₂:Ce (YAG:Ce), or forms of that phosphor with substituents or additions, as the specified phosphor.  Twelve examples of the use of such a phosphor are provided.  In some examples, two such fluorescent materials are used.  There are two comparative examples.  The comparative examples do not use a garnet fluorescent material. 

23. Comparative Example 1 concerns the use of cadmium zinc sulphide (Cd,Zn)S as the fluorescent material.  As I have noted, the specification teaches that, in use, this material darkens and leads to lowered light-extracting efficiency.  Nevertheless, the LED formed with this material showed, immediately after energisation, the emission of white light, albeit with low luminescence.  Thus, it provided a white LED but not one that was satisfactory according to the teaching of the specification.  I will refer again to this example when discussing the applicant’s work directed to developing a white LED. 

24. Comparative Example 2 concerns the use of two organic dyes rather than garnet fluorescent materials.  As I have noted, the specification teaches that when organic dyes are used, electrophoresis may occur, resulting in a change in the colour tone of the emitted light.  It is implicit in the description of Comparative Example 2 that white light was emitted.  A weatherability test (equivalent to irradiating the material with sunlight for one year) and a reliability test (energising the material to emit light at a constant temperature of 70° C while measuring luminance and colour tone at different times) were carried out.  When the LED of Comparative Example 2 was compared with the LED of Example 9, which used a combination of garnet fluorescent materials, the LED of Example 9 experienced less deterioration.  Once again it would seem that the specification does not accept that Comparative Example 2 provides a satisfactory white LED. 

25. Secondly, although the general formula of claim 3 covers a phosphor containing Sm as well as Y and/or Gd, and Ga as well as, or in substitution for, Al, it includes the phosphor YAG:Ce.  Therefore, it can be said that, at its simplest, the light emitting device claimed in claim 3 is one in which a nitride compound semiconductor (the light emitting component) is combined with YAG:Ce.

26. Thirdly, claim 3 does not, in terms, require the creation of white light, nor white light of any particular nature, quality or colour rendering.  Nor does it require that the light emitting device be suitable for any particular application; there are no requirements of stability, durability, efficiency or performance expressed as essential features of the invention. 

27. Nevertheless, the specification makes clear that the invention is a light emitting device that emits white light.  The present case is an example of where the context provided by the specification rises up to insist that claims 1 and 3 are directed to such a device:  International Business Machines Corporation v Smith, Commissioner of Patents (1992) AIPC 90-853 at 38,160-38,161. The specification teaches that the wavelength of the emitted light (and hence its colour rendering) can be varied by choices made within the scope of the general formula.

28. Further, the specification makes clear that an object of the invention is to provide a light emitting device with high luminescence, and which experiences only extremely low degrees of deterioration in emission light intensity, light emission efficiency and colour shift over a long period of use. 

29. In this connection, the specification states:

    The present applicant completed the present invention through researches based on the assumption that a light emitting device having a light emitting component and a fluorescent material preferably meets the following requirements to achieve the above-mentioned object.

    (1)The light emitting component is preferably capable of emitting light of high luminance with light emitting characteristic which is stable over a long time of use.

    (2)The fluorescent material being provided in the vicinity of the high-luminance light emitting component, preferably shows excellent resistance against light and heat so that the properties thereof do not change even when used over an extended period of time while being exposed to light of high intensity emitted by the light emitting component (particularly the fluorescent material provided in the vicinity of the light emitting component is exposed to light of a radiation intensity as high as about 30 to 40 times that of sunlight according to our estimate, and is required to have more durability against light as light emitting component of higher luminance is used).

    (3)With regard to the relationship with the light emitting component, the fluorescent material is preferably capable of absorbing with high efficiency the light of high monochromaticity emitted by the light emitting component and emitting light of a wavelength different from that of the light emitted by the light emitting component.

    (As in original.)

30. It can be taken that each embodiment of the invention that is claimed is a light emitting device (whether as an LED, a display device or some other light emitting device), or a method of preparing a light emitting device, that is directed to meeting these requirements.  This is not to say that these requirements are imported as essential features of the invention that is claimed—as if the claims were limited by result.  It does acknowledge, however, that the invention is directed to a white light emitting device that should attain these preferable (in the sense of desirable) attributes.  These are the “promises” that the specification makes.

    AN ISSUE OF CONSTRUCTION:  INFRINGEMENT

    The issue

31. There is an issue of construction concerning claim 3 which is determinative of the question of infringement.

32. Claim 3 requires that the light emitting device include a phosphor capable of absorbing a part of light emitted by the light emitting component and emitting light of a wavelength different from that of the absorbed light, “wherein the phosphor contains fluorescent material” (my emphasis) represented by the general formula. 

33. The applicant submitted that, while the integers of claim 3 are essential features of the invention that is claimed, those integers are not exhaustive of the things that can make up the claimed light emitting device.  The applicant argued that “contains” is used in claim 3 in an inclusive sense.  Thus, the claimed device is not limited to the use of a single phosphor, or perhaps more accurately, a single fluorescent material.  The applicant submitted that it is essential that the device includes fluorescent material of the stated formula, but other phosphor compounds can be present.  Thus, if fluorescent material of the general formula is present, infringement cannot be avoided by adding other fluorescent material to the light emitting device.

34. The respondent submitted that, properly construed, claim 3 only permits a phosphor of the stated formula.  It argues that “contains” must be construed in an exclusive sense.  The respondent also argued that, even if the word “contains” is construed in an inclusive sense—so as to contain something other than the fluorescent material (such as the resin with which it is mixed)—the fluorescent material cannot contain fluorescent material other than the garnet fluorescent material of the general formula.  The respondent submitted that this construction is consistent with the whole of the specification.  It further argued that there is no description or suggestion of any embodiment in which the light emitting device contains any fluorescent material other than garnet fluorescent material.  It argued that the specification makes plain that it is the use of garnet fluorescent material that will achieve the advantages promised for the invention in the specification.

35. When read in isolation, the word “contains” is capable of supporting either construction.  The question is, in what sense is “contains” used in claim 3?

36. The parties referred to a number of standard authorities on claim construction. 

37. The respondent referred to Welch Perrin & Co Pty Ltd v Worrel (1961) 106 CLR 588 at 609-610 for the proposition that the claims of a patent must be construed in the context of the specification as a whole.

38. The applicant emphasised that a patent should be given a purposive construction rather than a purely literal one:  Decor Corporation Pty Ltd v Dart Industries Inc (1988) 13 IPR 385 at 400; Catnic Components Ltd v Hill & Smith Ltd [1982] RPC 183 at 242-243; H Lundbeck A/S v Alphapharm Pty Ltd (2009) 177 FCR 151 at [118]-[129]. The applicant submitted that a construction that would lead to a foolish result, or one that the patentee could not have contemplated, is to be avoided in favour of another construction that would lead to the opposite result: Electric & Musical Industries Ltd v Lissen Ltd [1938] 4 All ER 221 at 224-227. Relatedly, the applicant relied on Jacob J’s injunction in Tickner v Honda Motor Co Ltd [2002] EWHC 8 at [28] that, in determining the “purpose of the patent” one must be “fair to the patentee”. This observation must be seen in its context, where Jacob J was discussing “purposive construction”. The full passage should be quoted to understand what Jacob J meant by being “fair to the patentee”:

    … You learn the inventor’s purpose by understanding his technical contribution from the specification and drawings.  You keep that purpose in mind when considering what the terms of the claim mean.  You [choose] a meaning consistent with that purpose – even if that involves a meaning which, acontextually, you would not ascribe to the word or phrase.  Of course in this exercise you must also be fair to the patentee – and in particular must not take too narrow a view of his purpose – it is the widest purpose consistent with his teaching which should be used for purposive construction. 

39. Here, the applicant said, the purpose the invention is encapsulated by the Abstract appended to the patent application, which refers to:

    … a white light emitting diode having high luminance and a light emitting characteristic which is not deteriorated even when the diode is used for a long period of time….

40. The applicant also called in aid a line of cases which are to the effect that infringement cannot be avoided by merely adding features to a claimed combination.  The applicant placed particular significance on the following statement by the Full Court in Fresenius Medical Care Australia Pty Ltd v Gambro Pty Ltd (2005) 224 ALR 168; [2005] FCAFC 220 (Fresenius) at [70]:

    … The inclusion of additional integers to a claimed combination does not necessarily avoid infringement.  If those additional integers are properly characterised as inessential or do not make a new working of the combination and all of the essential integers of the claimed combination are present, there will be infringement.  Where a patentee defines the claimed invention as consisting of a number of essential integers, it is no answer to infringement that the claimed combination is taken but additional integers are added that do not affect and are not part of the invention.

41. The applicant relied on similar statements in Seafood Innovations Pty Ltd v Richard Bass Pty Ltd (2011) 92 IPR 1; [2011] FCAFC 83 at [24] and Bitech Engineering v Garth Living Pty Ltd (2010) 86 IPR 468; [2010] FCAFC 75 at [30]. The applicant also referred to Bowen LJ’s aphorism in The Wenham Gas Company v The Champion Gas Lamp Company (1891) 9 RPC 49 that the “superadding of ingenuity to a robbery does not make the operation justifiable”.

42. The applicant’s reliance on this line of authority cannot be used to support its submissions on the question of construction.  The question of claim construction is separate from, and anterior to, the question of infringement.  Further, one does not construe the claims of a patent with one eye on the product that is said to be an infringement.

    Conclusion and reasons

1. The light emitting device claimed in claim 3 is one in which the phosphor is a single fluorescent material represented by the general formula.  Claim 3 does not claim a device in which the phosphor is the defined fluorescent material together with one or more other fluorescent materials. 

2. The specification clearly points to this construction.  In describing the invention, the specification takes as one of its starting points the fact that, even though LEDs of a “conventional” kind (i.e., as described in the specification) are capable of emitting white light by combining the blue light of the LED with a fluorescent material that absorbs this light and emits yellowish light, deterioration of the fluorescent material is a problem.  The problem thus presented is one directed to the characteristics of the fluorescent materials that are used, whether those materials are organic or inorganic phosphors or some other similarly functioning material.  Principally, the invention is directed to overcoming this problem. 

3. As I have noted, so far as fluorescent materials are concerned, the invention described in the specification is directed to garnet fluorescent materials of a particular kind.  The broadest definition of these materials is provided in claim 1.  Claim 3 is directed to a more particular subset of these materials. The consistory statement for claim 3 (at page 8, lines 13-17) says:

   In the light emitting device of the present invention, the phosphor may be a fluorescent material represented by a general formula (Re_1-rSm_r)₃(Al_1-sGa_s)₅O₁₂:Ce, where 0≤r<1 and 0≤s≤1 and Re is at least one selected from Y and Gd, in which case good characteristics can be obtained similarly to the case where the yttrium-aluminium-garnet fluorescent material is used. 

4. A similar statement appears at page 11, lines 20-23 of the specification.

5. It is clear that each consistory statement is talking about specific fluorescent material.  Each statement describes the phosphor as a fluorescent material of the stated formula.  The consistory statements do not even suggest, let alone say, that the phosphor can be anything other than the specifically stated fluorescent material defined by the general formula. 

6. Claim 3 should be read in that light.  The person skilled in the art, reading the specification as a whole, with its description of various specific embodiments of the invention, would understand that claim 3 claims the light emitting device described in the consistory statement on which it is based.

7. Significantly, the consistory statement at page 8, lines 13-17 of the specification promises that, when this specific fluorescent material is used, “good characteristics can be obtained”.  These characteristics are said to be similar to those obtained when YAG:Ce is used (it being remembered that YAG:Ce itself falls within the general formula of claim 3, although material other than YAG:Ce is covered). 

8. In this connection, the specification teaches that YAG:Ce:

   … has excellent resistance against light so that the fluorescent properties thereof experience less change even when used over an extended period of time while being exposed to light of high intensity.  This makes it possible to reduce the degradation of characteristics during long period of use and reduce deterioration due to light of high intensity emitted by the light emitting component as well as extraneous light (sunlight including ultraviolet light, etc.) during outdoor use, thereby to provide a light emitting device which experiences extremely less color shift and less luminance decrease.  The light emitting device of the present invention can also be used in such applications that require response speeds as high as 120 nsec., for example, because the phosphor used therein allows after glow only for a short period of time.

   (As in original.)

9. This teaching strikes at the problems said to be associated with the “conventional” LEDs, which the invention seeks to overcome.  The promise is that use of the fluorescent material defined by the general formula in claim 3 will achieve similarly good characteristics.  The promised characteristics are secured by the word “contains” in claim 3.

10. In a later part of the specification (at page 36, lines 4-12), further reference is made to this embodiment and its promised advantages: 

    As for the fluorescent material, a fluorescent material represented by general formula (Re_1-rSm_r)₃(Al_l-sGa_s)₅O₁₂:Ce, may also be used as the phosphor.  Here 0≤r<1 and 0≤s≤1, and Re is at least one selected from Y, Gd and La.  This configuration makes it possible to minimize the denaturing of the fluorescent material even when the fluorescent material is exposed to high-intensity high-energy visible light emitted by the light emitting component for a long period of time or when used under various environmental conditions, and therefore a light emitting diode which is subject to extremely insignificant color shift and emission luminance decrease and has the desired emission component of high luminance can be made.

11. It will be noted that, in this embodiment, Re can be La.  Nonetheless, the description of the fluorescent material plainly covers material of the general formula and speaks of the advantages of using that material.

12. In context, “contains”, as used in claim 3, can only be a reference to the defined fluorescent material as the phosphor of the claimed device, not some combination involving, for example, other fluorescent materials about which the specification says nothing and about which it can make no promises as to their characteristics when used in a light emitting device containing the nitride compound semiconductor as the light emitting component.

13. This construction is supported by other aspects of the description of the invention.  In particular, when a specific embodiment of the invention can contain more than one fluorescent material as the phosphor, the specification says so; in these cases, the specification describes the materials that can be used.  This assists with the meaning of “contains” when used throughout the claims. 

14. In arguing for its construction, the applicant pointed to the use of the word “including” in claim 1 (on which claim 3 is dependent).  The applicant submitted that the use of “including” shows that the essential integers of claim 3 are not exhaustive of the features of the device that is claimed. 

15. I do not accept the purport of this submission.  The word “including” shows that components of the light emitting device, other than the light emitting component and the phosphor, may be present.  Indeed, it is accepted that other componentry must be present in order for the light emitting device to function.  But claim 1 then proceeds with greater detail to specify the characteristics of the light emitting component and the phosphor.  At this point, the effect of the word “including” is spent in relation to those materials:  the light emitting component and the phosphor are defined.  Claim 3 proceeds with even greater detail to specify the phosphor to be used by reference to the stated fluorescent material.

16. The applicant submitted that the construction I have found fails to give meaning to the distinction drawn in claim 3 between the phosphor and its constituent fluorescent material.  I accept that claim 3 makes this distinction.  I do not accept that the construction I have found fails to give meaning to it.  The use of the phosphor in claim 3 is derived from the use of the same words in claim 1.  Their use in claim 3 is integral to confining the phosphor of claim 1 to the specific fluorescent material stated in claim 3.

17. The applicant referred to claim 6 in aid of its construction.  Claim 6 is:

    A light emitting device according to claim 3, wherein the phosphor contains two or more fluorescent materials of different compositions represented by a general formula (Re_1-rSm_r)₃(Al_l-sGa_s)₅O₁₂:Ce, where 0≤ r<1 and 0≤s≤1 and Re is at least one selected from Y and Gd.

18. The applicant pointed to the fact that claim 6 is expressed to be dependent on claim 3 and, for that reason, must be narrower than claim 3.  The applicant then argued that claim 6 had been narrowed “to exclude a phosphor containing only one fluorescent material”.

19. This submission does not assist the applicant’s construction of claim 3.  Claim 6 confirms the construction I have found.  The invention of claim 6 is distinguished from the invention of claim 3 in that, in claim 6, two or more fluorescent materials represented by the general formula are used as the phosphor.  This confirms that, in claim 3, the words “fluorescent material” are used advisedly to refer to a single fluorescent material, being material represented by the general formula.  The applicant’s construction, which proceeds on the basis that the phosphor merely include fluorescent material represented by the general formula, would suggest that claim 6 is largely redundant because, from the perspective of infringement, claim 3 would also do the work of claim 6. This cannot have been intended by the drafter of the specification.  Claim 6 is an example of where the specification is specific when more than one fluorescent material can be used as the phosphor.  Claims 7 and 8 provide further examples.  Claim 3 confines the phosphor to a specific material (i.e., material within the general formula).  Claims 6, 7 and 8 each confine the phosphor to specific materials (i.e., each material of a different composition but nevertheless within the general formula).

20. The applicant called in aid NV Philips Gloeilampenfabrieken v Mirabella International Pty Limited (1993) 44 FCR 239 (Philips (FCAFC)) at 259 to support its construction of claim 3 by relying on the Full Court’s construction of another claim in another patent, which concerned another light emitting device—a low-pressure mercury vapour discharge lamp. The applicant’s reliance on Philips (FCAFC) does not advance its case in this regard.  In the present case, the task of the Court is to construe claim 3 in the particular context of the specification in suit.  In any event, in construing the patent in Philips (FCAFC), Lockhart J (with whom the other members of the Full Court agreed) had regard to the fact that, if the luminescent layer of the discharge tube in that invention were to be confined to one phosphor or a single chemical compound, the object of the invention could not be achieved.  There is no evidence before me of any similar consideration in this case.  Indeed, the teaching of the specification is to the contrary.

21. The applicant also pointed to two passages in the specification which, it submitted, supported the contention that “contains” in claim 3 is used inclusively, so as not to exclude the presence of other fluorescent materials.  These passages concern an embodiment of the invention which the specification refers to as “Embodiment 2” or “the second embodiment”.

22. The first passage is page 36, lines 15-19 of the specification:

    Now the phosphor used in the light emitting component of the second embodiment will be described in detail below.  The second embodiment is similar to the first embodiment, except that two or more kinds of phosphors of different compositions activated with cerium are used as the phosphor, as described above, and the method of using the fluorescent material is basically the same. 

23. The second, earlier, passage is at page 35, lines 15-20 of the specification:

    The light emitting diode of the second embodiment of the present invention is made by using an element provided with gallium nitride compound semiconductor which has high-energy band gap in the light emitting layer as the light emitting component and a fluorescent material including two or more kinds of phosphors of different compositions, or preferably yttrium-aluminum-garnet fluorescent materials activated with cerium as the phosphor. …

24. The applicant placed particular emphasis on the fact that the second passage expresses no more than a preference that YAG phosphor activated by Ce be used, at least in this embodiment.  In essence, the applicant’s contention was that these passages show that more than one phosphor can be used in an embodiment of the invention and that, when using a combination of phosphors, YAG phosphors activated by Ce are preferred but not essential. 

25. There is, of course, no denying that the word “preferably” is used in the second passage.  Considered in isolation, it appears to give the words “… a fluorescent material including two or more kinds of phosphors of different compositions ...” wide scope.  However, other passages of the specification dealing with the same embodiment make clear that this is an embodiment in which two YAG phosphors activated by Ce are used.  I refer, in particular, to page 37, lines 11-24; page 37, line 25 to page 38, line 2; page 38, line 21 to page 39, line 6; page 39, lines 7-16; and page 39, line 24 to page 40, line 1.  When these passages are read with the two passages quoted above, it is clear that the word “preferably” is used infelicitously and cannot be accorded its literal meaning.  I am satisfied that the person skilled in the art would understand the second embodiment as one in which two YAG phosphors activated by Ce are used, not merely used preferentially.  I am not persuaded, therefore, that these passages assist the applicant’s case on the proper construction of claim 3 which, in any event, claims a different embodiment of the invention based on other passages in the specification.

26. The applicant alleges, and the respondent accepts, that the respondent has exploited, in the patent area, the following white LED products manufactured by Everlight: 

    ·Model number 62-217D/QK2C-S5050R1R3B42Z15/2T (Device A);

    ·Model number 62-217D/QK2C-S5757R1R3B42Z15/2T (Device B);

    ·Model number 62-217D/QK2C-S6565R1R3B42Z15/2T (Device C);

    ·Model number JU1215-KT507N7-12507-090T (Device D);

    ·Model number 45-21S/KK2C-S5757L1L4B2Z3/2T (Device E); and

    ·Model number 67-21/LK2C-BX5070B3B6B2/2T (Device F).

27. The only issue on infringement that divides the parties is this:  although each product includes a fluorescent material that is YAG:Ce, which is within the general formula of claim 3, each product also includes other fluorescent material that is not within the general formula.  Based on Mr Lu’s evidence (see [30] above), which I accept, Devices A to E include, in addition, a garnet fluorescent material that is not within the general formula and one or more other, non-garnet fluorescent materials.  Exceptionally, Device F includes, in addition, only a non-garnet fluorescent material. 

28. Given that each product includes YAG:Ce, does it follow that, in each case, infringement of claim 3 has been established?  Based on the construction I have found, the answer to this question is “no”. 

29. The applicant’s case is not advanced by reliance on statements on infringement such as that found in Fresenius at [70]. The question is whether all the essential features of the invention claimed in claim 3 are present in an accused product. All the essential features are not present because claim 3’s requirements as to the phosphor are not met.

30. As I have said, the light emitting device of claim 3 is one in which the phosphor is a single fluorescent material represented by the general formula.  As a matter of definition, the light emitting device of claim 3 does not extend to one where the phosphor contains two or more fluorescent materials, even if one of them is fluorescent material represented by the general formula.  The present case is an instance where full force is to be given to the principle that matter that is not claimed is disclaimed.  Put simply, none of the accused products accords with the definition of the light emitting device claimed in claim 3. 

31. This is not to give claim 3 an unduly narrow construction.  Claim 3 is of a scope that provides for a choice in the composition of the fluorescent material whilst adhering to the general formula.  In other words, the general formula permits adjustments and substitutions to be made.  Thus, the invention can be practised in a way that allows the user, by permitted adjustments and substitutions, to control the wavelength of the emitted light of the device, whilst at the same time attaining the desirable attributes that are promised in the specification for this particular embodiment.

32. For these reasons, the applicant’s case on infringement has not been established and must be dismissed.

    Claim 1

33. It is convenient at this point to say something about the construction of claim 1, even though the applicant does not put claim 1 in suit. The construction of claim 1 arises in the context of the respondent’s challenge to validity based on s 40 of the Act.

34. As I have noted, claim 1 contains the broadest definition of the phosphor that can be used.  The phosphor is a garnet fluorescent material of a particular kind.  Claim 2 confines the phosphor to YAG and, as discussed, claim 3 confines the phosphor even further to fluorescent material represented by the general formula (which, amongst other things, is activated by Ce).

35. Claim 5 is dependent on claim 2 and provides a more limited embodiment where the fluorescent material is two or more YAG materials of different composition, activated with Ce.  Claim 5, like claims 6, 7 and 8, is another example where the specification is specific when one or more fluorescent materials can be used as the phosphor.

36. All these claims use the word “contains” in the exclusive sense I have described when construing claim 3.  When “contains” is used with respect to the phosphor, it means that the phosphor in the light emitting device is the fluorescent material specified in the relevant claim, not some other phosphor or admixture of fluorescent materials.

37. I now turn to consider the respondent’s case on invalidity more generally.  It is convenient to start with the evidence concerning the development of the claimed invention.

    THE DEVELOPMENT OF THE INVENTION

    Background

38. In 1991, the applicant’s LED Development Team developed a gallium nitride (GaN) LED which emitted near-UV light and violet light.  The luminance of the emitted light was not good.  With the aim of improving the luminance, the LED Development Team combined the LED with fluorescent materials.  This was the first time that this idea had been raised within the applicant.  This work led to Japanese Patent 5-152609, filed on 25 November 1991.  This patent is referred to on page 2 of the specification.

39. In November 1993, the applicant announced that it had developed the world’s first high-brightness blue LED using a GaN semiconductor.  Before this announcement, high-brightness blue LEDs had been made available within the applicant for research purposes.  The development of this LED was a significant scientific achievement.  One of the inventors, Shuji Nakamura, received the Nobel Prize in Physics in 2014 for his work. 

40. In 1993, the applicant established its Backlight Development Team.  This team was to attempt to develop a white backlight (such as used in computer screens) by using a fluorescent material to convert the wavelength of the GaN blue LED.  The team’s first efforts focused on the use of organic fluorescent materials.  At that time, some established applications used organic fluorescent materials (such as organic dyes) which could be excited by visible light.  As noted in paragraphs 61-62 of the supplementary primer, light that is capable of producing a visual sensation to the human eye ranges from about 360 nm to about 830 nm, and includes all colours from red to violet.  However, it is common to say that the visible region of the spectrum ranges from 400 nm to 700 nm, as perception varies from person to person.  The visible region of the spectrum is bounded by the UV (<400nm) and infrared (IR) (>700nm) regions.  These regions are not precisely bounded, and may overlap into other regions. 

41. The applicant was using organic fluorescent materials in other applications.  In 1993, the LED Development Team developed a green LED using the combination of a blue LED and a green organic fluorescent material.  This work led to Japanese Patent H07-99345, filed on 28 September 1993.  This patent is also referred to on page 2 of specification.  The lifetime of the developed green LED was only several hours because the green organic fluorescent material degraded due to the strong light and heat from the LED.

1. The first white backlight developed by the Backlight Development Team, in 1993, was a combination of a blue LED with red and green organic fluorescent materials disposed on a light guide plate.  The Backlight Development Team developed an alternative combination of a blue LED with yellow and orange organic materials disposed on a light guide plate.  This work led to Japanese Patent 7-176794, filed on 17 December 1993, and Japanese Patent 8-7614, filed on 17 June 1994.  The developed white backlight was subsequently modified and put into practical use in 1994.  This used a colour conversion sheet made of organic fluorescent materials which was placed on the light guide plate to dilute the strong light emitted from the blue LED.  This resulted in a reduction of the light density because light from the blue LED was spread over the entire surface of the light guide. This helped to stabilise and reduce degradation of the organic fluorescent materials. 

2. In March 1995, the applicant produced, by way of a trial, a disposable white LED for use as the light source for an endoscope.  It used yellow and orange, or alternatively yellow and red, organic fluorescent materials.  This application did not require the LED to have a long lifetime, simply because the light source was intended to be disposable. 

3. To the present time, the applicant continues its research into organic fluorescent materials. 

   The development of a white LED

4. The applicant was, in 1996, and remains today, the world’s largest manufacturer of inorganic phosphors.

5. At the beginning of 1996, the President of the applicant, Mr Eiji Ogawa, gave an instruction that the applicant was to begin investigating the option of combining the blue LED with an inorganic phosphor to achieve a white LED.    

6. A team was created, called the White LED Development Team. Mr Yori Shimizu, then the General Manager of the Engineering Department of the Second Division (Optoelectronics Products Business Unit), was appointed as team leader. His direct supervisor was Mr Shinomiya, who (as I have noted at [27] above) is now the Managing Director of the applicant. Mr Ogawa’s instruction was given directly to Mr Shinomiya, who shortly thereafter established the White LED Development Team.

7. In cross-examination, Mr Shinomiya gave an answer that indicated that Mr Ogawa’s instruction was given in April or May 1996, rather than at the beginning of 1996. I think that, in giving that evidence, Mr Shinomiya may well have mistaken this instruction with a later instruction given by Mr Ogawa concerning the need to extend the search for phosphors beyond the class of phosphors the applicant was investigating in April/May 1996: see below at [138]. I find that Mr Ogawa’s initial instruction was given at the beginning of 1996.

8. Mr Shinomiya said that he and Mr Shimizu “had previously been involved in many inorganic phosphor developments” for the applicant.  He said that, because of that experience, he and Mr Shimizu were the people within the applicant who had the most technical knowledge concerning inorganic phosphors. 

9. Mr Shinomiya said that, at this time, inorganic phosphors were classified according to their applications.  There were three classifications:  phosphors for televisions (electron beam excitation), phosphors for fluorescent lamps (UV-ray excitation) and phosphors for X-ray machines (X-ray excitation).  Mr Shinomiya said that, despite the technical knowledge he had gained concerning inorganic phosphors, he did not, at this time, know of an inorganic phosphor that could be excited by visible light.  He said that Mr Shimizu did not suggest that he knew of such an inorganic phosphor.

10. Mr Shinomiya said that he and Mr Shimizu’s approach was to search for a phosphor within those already produced by the applicant.  He said that he and Mr Shimizu could have considered searching in the scientific literature for phosphors that could be excited by visible light.  However, they did not adopt that approach because, even if such a phosphor could be found, they would have to synthesise it if the applicant did not already produce it.  Synthesising a new phosphor required at least one year’s work. 

11. Mr Shimizu suggested that the search within the phosphors that the applicant already produced should be for those with a red, green or yellow body colour because a phosphor which is excited by blue light should show some body colour under natural light.  Here, it is necessary to understand that, ordinarily, a phosphor will appear white to the human eye because it reflects visible light.  A phosphor which absorbs visible light and emits light of a different wavelength should appear to the human eye as a colour other than white.  Mr Shinomiya said that, carrying out an inspection of this type, would only enable an initial investigation of potential phosphor candidates, rather than a conclusion that a phosphor would in fact be excited by visible light.  This is because phosphor body colour is influenced by reflection as well as luminescence. 

12. Mr Shinomiya said that, in another conversation, Mr Shimizu suggested, as a possibility, zinc cadmium sulphide phosphor doped with (i.e., activated by) silver (ZnCdS:Ag).  Mr Shimizu’s suggestion was based on the fact that ZnCdS:Ag phosphor has a strong yellow body colour.  Mr Shinomiya said that, at the time, he was aware of this fact.  He said that he was also aware that ZnCdS:Ag phosphor emits yellow light when excited by an electron beam.  This phosphor was available to the applicant for use in monochrome cathode ray tube (CRT) display applications. 

13. Mr Shinomiya said that, accordingly, the focus of the initial investigations was to identify inorganic phosphors having a body colour, such as red, green or yellow.  In early 1996, Mr Shimizu selected about 20 sulphide phosphors as candidates, including ZnCdS:Ag, from the several hundred phosphors in the company.  Mr Shimizu carried out testing on the sulphide phosphor candidates.  He was assisted by Mr Toshio Moriguchi, who had previously been in the Backlight Development Team.  Amongst other things, Mr Moriguchi’s role during this period was to investigate the sulphide phosphor candidates and narrow the list.  Mr Kensho Sakano also assisted by preparing and testing specific LED samples as requested by Mr Shimizu. 

14. Based on this work, ZnCdS phosphor was confirmed as the preferred candidate.  Further specific development work was carried out, including determining an appropriate ratio of CdS to ZnS in the phosphor, and determining the preferred activator.  Before this work was carried out, Mr Shimizu was aware that ZnS-based phosphors were susceptible to water.  He nevertheless expressed the view to Mr Shinomiya that the effect of water could be excluded in an LED application because the phosphor would be sealed with a resin.  Mr Shinomiya said that, based upon other work undertaken within the applicant, he was aware that ZnS-based phosphors had good stability in CRT applications where water was not an environmental factor. 

15. Specific testing was done using ZnCdS:Ag phosphor.  It was found that while the phosphor produced a white colour that was acceptable, it degraded within one day.

16. Mr Shinomiya said that, given its high reliability in the CRT environment, it was very surprising to him that ZnCdS:Ag phosphor would degrade so quickly in the LED environment simply because moisture was present.  Mr Shimizu’s observation, as reported to Mr Shinomiya, was that, under strong light and heat, the phosphor seemed to be blackened by the very tiny amount of water that either remained in the resin or entered from outside the resin. 

17. Further development work was carried out using a ZnCdS:Cu,Al phosphor.  The LED also emitted white light of an acceptable colour.  This LED is, in fact, used as Comparative Example 1 disclosed at page 49, line 18 to page 50, line 9 of the specification: 

    (Comparative Example 1)

    Formation of a light emitting diode and life tests thereof were conducted in the same manner as in Example 1 except for changing the phosphor from (Y_0.8Gd_0.2)₃Al₅O₁₂:Ce to (ZnCd)S:Cu, Al.  The light emitting diode which had been formed showed, immediately after energization, emission of white light but with low luminance.  In a life test, the output diminished to zero in about 100 hours.  Analysis of the cause of deterioration showed that the fluorescent material was blackened.

    This trouble is supposed to have been caused as the light emitted by the light emitting component and moisture which had caught on the fluorescent material or entered from the outside brought about photolysis to make colloidal zinc to precipitate on the surface of the fluorescent material, resulting in blackened surface.  Results of life tests under conditions of energization with a current of 20mA at 25°C and 20mA at 60°C with 90% RH are shown in Fig. 13 together with the results of Example 1.  Luminance is given in terms of relative value with respect to the initial value as the reference.  A solid line indicates Example 1 and a wavy line indicates Comparative Example 1 in Fig. 13.

    (As in original.)

18. The “life test” referred to in this disclosure involves testing the product under harsher conditions than normal, for example at a temperature of 60°C and  90% humidity.  The purpose is to test how the phosphor performs under conditions which accelerate its life cycle.  In his affidavit, Mr Shinomiya gave the following evidence:

    The problems the White LED Development Team experienced with the ZnS phosphor highlight one of the fundamental challenges involved with phosphor research.  Even when a phosphor can be successfully employed in one operating environment, it cannot be assumed that it will have sufficient durability in another environment.  This means that any candidate must be tested to ascertain whether or not it will actually have the required luminance and durability in a new environment.  The light, heat and moisture in the LED environment can be particularly challenging in terms of durability.

19. In about late April or May 1996, Mr Ogawa visited Mr Shinomiya and Mr Shimizu.  Mr Ogawa said that there should be many other phosphors that can emit yellow light like the ZnS-based phosphors.  He inquired whether the White LED Development Team had “tested all of them”. 

20. In his affidavit, Mr Shinomiya placed this event after the testing of the ZnCdS phosphors.  In cross-examination, he accepted the possibility that the testing of the ZnCdS phosphors took place at the same time as the testing of YAG:Ce (which I describe in the following paragraphs).  The documents indicate that this is likely to be the case — at least there appears to have been an overlap in the testing of different classes of phosphors.  However, I do not understand Mr Shinomiya to have accepted that the testing of the ZnCdS phosphors and YAG:Ce was conterminous.  In cross-examination, Mr Shinomiya also accepted the possibility that ZnCdS phosphors were being tested for the purpose of comparing them with YAG:Ce.  Whilst Mr Shinomiya accepted this possibility, I do not understand his evidence to go so far as accepting that to be the fact.  Also, his evidence was given with respect to a particular test.  As I understood Mr Shinomiya’s evidence in this regard, he did not know whether the proposition put to him was a fact, so far as that particular test was concerned.

21. The day after the conversation with Mr Ogawa, Mr Shinomiya and Mr Shimizu went to an inspection room located in the applicant’s Inspection Building, where the applicant’s phosphor reference samples were stored.  Mr Shinomiya said that he and Mr Shimizu carefully observed the body colour of several hundred sample phosphors, one by one.  Mr Shinomiya gave this evidence:

    The samples were stored in a variety of ways; some were stored in plastic bags, others were in transparent bottles.  If a phosphor was in a black plastic bag or in a bottle with a cover to prevent exposure to light, we opened them so the phosphors were exposed to light during our observation.  We were in the inspection room for more than two hours to observe all of the samples there.  We did not look at any specification sheets, just the phosphor samples themselves.

22. Mr Shinomiya said that one of the phosphor samples that he and Mr Shimizu observed was YAG:Ce.  Its body colour was slightly yellowish in appearance.  Mr Shinomiya said that, at this time, he knew of this phosphor, but he did not know until then that its body colour was slightly yellow (or that it had a body colour other than white).  YAG:Ce was available at Nichia because it had been used in electron beam excitation applications to emit green light, and for flying spot scanners.  Mr Shinomiya said that, at that time, he had “never seen a real visible light emission of YAG phosphor in a flying spot scanner”.

23. Mr Shinomiya said that, at this time, he also knew that YAG:Ce was used as an optical crystal for a laser oscillation.  In cross-examination he accepted that, at that time, he knew that the phosphor was very stable when used in that application.

24. Mr Shinomiya said that not all of the phosphors owned by the applicant were stored in the inspection room.  Mr Shinomiya gave an instruction that other phosphor samples held by the applicant were to be collected for inspection. 

25. Mr Shinomiya said that, following his and Mr Shimizu’s inspection of samples in the inspection room, YAG:Ce was identified as the preferred candidate for further testing because of its slightly yellow body colour.  In late May 1996, the White LED Development Team produced LED samples using YAG:Ce and managed to create an LED that emitted a weak greenish white colour.  This confirmed that the light emission had a broad emission spectrum when excited by a blue light.  It also meant that there was a possibility that a white LED suitable for various applications could be obtained.  At this juncture, it should be recalled that YAG:Ce falls within the definition of the phosphor of claim 3 of the patent.

26. Mr Shinomiya said that while YAG:Ce was stable in a laser application, it was not known whether the phosphor powder, having a diameter of only several micrometres, would have sufficient durability when moved to the LED environment.  He said that this was particularly so in light of the team’s experience with ZnCdS.  Experiments were carried out on a test sample.  The experiments showed that the phosphor had good durability in the LED environment.

27. I note that various test reports are in evidence, including a test report dated 30 May (known to be in 1996) and 6 June 1996 that concern the testing and comparison of YAG:Ce and ZnCdS phosphors. 

28. Once YAG:Ce had been confirmed as the lead candidate, the remaining problem was to modify its greenish white colour to achieve a more desirable tone of white.  Mr Shinomiya said that this could be achieved by reducing the colour temperature of the phosphor.  Mr Shimizu requested that experiments be performed by the applicant’s Phosphors Group.  This stage of the work commenced in early June 1996.  It was carried out by Mr Noguchi.  Mr Shimizu’s idea was to create a more desirable white LED by adding a red light component.  He proposed introducing a co-activator which emitted red light, such as Ce with Sm³⁺, Ce with Eu³⁺ or Ce with Mn.  The work with the coactivators was not successful. 

29. Mr Shinomiya said that Mr Noguchi took it upon himself to prepare YAG:Ce with some of the Y substituted with Gd in order to make the wavelength of the emitted light longer.  Mr Noguchi’s plan was to change the matrix of the phosphor and adjust the content of Ce as an activator.  The test with the modified YAG:Ce showed very good results.  It produced desirable white light and had the flexibility of shifting the colour temperature in a broad range.

30. In June 1996, a decision was made by the applicant to file a patent application in respect of the work undertaken by the White LED Development Team.  The patent in this proceeding derives from one of a number of applications that were made.

    THE PERSON SKILLED IN THE ART

31. As is well-recognised, the person skilled in the art is, for the purposes of the Act, a legal construct that sets the standard against which questions posed by the Act are to be answered. One such question is posed by s 7(2). That provision has been amended from time to time. The form of the provision applicable to the present case is shown in Reprint 2 of the Act:

    For the purpose of this Act, an invention is to be taken to involve an inventive step when compared with the prior art base unless the invention would have been obvious to a person skilled  in the relevant art in the light of the common general knowledge as it existed in the patent area before the priority date of the relevant claim, whether that knowledge is considered separately or together with either of the kinds of information mentioned in subsection (3), each of which must be considered separately.

32. Although identified as a single person, it is understood that the person skilled in the art may be a composite entity, frequently referred to as a team of persons:  General Tire & Rubber Company v Firestone Tyre & Rubber Company Limited [1972] RPC 457 (General Tire) at 485. In the present case, the respondent contended that the person skilled in the art is a team; in effect, the applicant contended otherwise.

33. The respondent says that the person skilled in the art is, relevantly, the person who, at the priority date, had knowledge of and experience in LEDs, phosphors and lighting together with knowledge of the basic physics and chemistry used in this field. 

34. On the other hand, the applicant says that the person skilled in the art is the person who, at the priority date, was skilled in semiconductors and not a person skilled in phosphors.  The applicant says that a person skilled in the art of phosphors would only be involved, if at all, at a later stage, after attempts to produce a white LED using only semiconductors had failed and the idea to use phosphors with a blue LED was conceived.

35. In my view, the respondent’s contention is correct.  Leaving aside the question of what is, and what is not, common general knowledge, the evidence establishes that, well before the priority date, the use of phosphors in lighting was ubiquitous.  For the proof of that proposition, one need only look to fluorescent lighting.  However, the evidence went much further than this.

36. Blasse G & Grabmaier B C, Luminescent Materials, Springer-Verlag, Berlin, 1994, is a standard textbook that provides an introduction to luminescent materials and solid state physics. A copy was available in the library of the University of Technology Sydney as at 17 November 1994. Parts of this work—referred to below as the Blasse extract—were tendered as prior art information available under s 7(3) of the Act. Leaving aside the question of whether it is available for that purpose, the Blasse extract illustrates various applications of luminescent materials, including as lamp phosphors, CRT phosphors, and X-ray phosphors. In the context of lamp phosphors, the Blasse extract discloses that luminescent lighting using lamp phosphors started even before the Second World War. The Blasse extract also includes a discussion on semiconductors, and on electroluminescence involving LEDs and semiconductor lasers. In its introduction to electroluminescence, the Blasse extract states:

    When a luminescent material can be excited by the application of an electric voltage, we speak of electroluminescence.  In order to convert electric energy from the applied voltage into radiation, three steps have to be considered:  excitation by the applied field, energy transport to the luminescent center, and emission from this center.  According to the voltage applied, one can distinguish between low-field or high-field electroluminescence.  Light emitting diodes, where energy is injected into a p-n junction, are typical of low-field electroluminescence.

1. There are other peculiarities concerning Document 1 and Document 2 and the manner of their creation.  Dr Kramer referred to a number of them.  These matters no doubt contributed to his suspicions that Document 1 and Document 2 were fabrications.  However, in light of the conclusion to which I have come, I do not propose to deal with these additional matters which, on the whole, would only provide more support for the conclusion that Document 1 and Document 2 are fabrications. 

2. Apart from the markings on Document 1 and Document 2, there is no evidence of their receipt by any person, other than Dr Richter’s evidence concerning Mr Schroeder’s testimony in respect of Document 2.  As I have said, I now reject Dr Richter’s evidence in this regard as inadmissible hearsay.  In any event, I can place no reliance on this aspect of Dr Richter’s evidence because, regardless of what Dr Richter heard Mr Schroeder say in the FPC proceeding, I am satisfied that Document 2 was fabricated by Mr Wustlich after the priority date.  I am satisfied that a document in the terms of Document 2 was not sent to Mr Schroeder before the priority date.

3. For these reasons, the respondent has not established that, at the priority date, the invention claimed in claims 1 and 3 was not novel.

   S 40 MATTERS:  LACK OF FAIR BASIS, DEFINITION AND CLARITY

4. The respondent contended that, if the applicant’s construction of claims 1 and 3 were to be adopted, then the invention, as so claimed, would not be fairly based on the matter described in the specification and would not define the invention.  The respondent also contended that the definition of the invention would not be clear.

5. I reject the respondent’s contentions that the invention, as so claimed, would not be defined or that the definition would not be clear.  A claim does not lack definition, and the definition does not lack clarity, simply because the claim admits of two arguable constructions and one construction of the claim is chosen over another as the correct construction.

6. As to the question of fair basing, my conclusion on the construction of claims 1 and 3, which rejects the applicant’s construction, means that this ground of invalidity, as advanced by the respondent, does not arise for consideration.

   CONCLUSION AND DISPOSITION

7. The originating application and the cross-claim should be dismissed.  I will hear the parties on the question of costs.  Each party is to submit a draft of the orders it proposes (including on costs) in light of the findings I have made.  Each party may make supporting submissions in writing, limited to three pages.  The applicant should provide its draft orders and submissions to my Associate by 4.00pm on 14 August 2017.  The respondent should provide its draft orders and submissions to my Associate by 4.00pm on 21 August 2017.  I will then deal with the matter on the papers.

I certify that the preceding four hundred and forty-five (445) numbered paragraphs are a true copy of the Reasons for Judgment herein of the Honourable Justice Yates.

Associate: 

Dated:       2 August 2017

SCHEDULE

Supplementary Primer

Contents

1......... ........ ........ ........ ........ ........ ........ ........ ........ ........ Light Emission........ 98
1A......... ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ .... Diode........ 99
2......... ........ ........ ........ ........ ........ ........ ........ ...... Light Emitting Diode........ 100
3......... ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ .. Phosphor........ 101
4......... .... Absorption and emission of light at different wavelengths........ 102
5......... ........ ........ ........ ........ ........ ... Nitride compound semiconductor........ 103
6......... ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ...... Garnet........ 104
7......... ........ ........ ........ ........ ........ ........ ........ ........ ........ .... Fluorescence........ 105
8......... ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ Activation........ 106
9......... ........ ........ ........ ........ ........ ....... The general formula of claim 3........ 107

9.1........ ........ ........ .. Structure of the general formula of claim 3........ 107
                 9.2........ ........ ........ ........ ........ ........ ........ ........ ........ .. Y₃Al₅O₁₂:Ce........ 109

10......... ........ ........ ........ ........ ........ ........ ........ ........ ........ ... Visible light........ 110
11......... ........ ........ ........ ........ ........ ........ ........ ........ Thermal quenching........ 113
12......... ........ ........ ........ ........ ........ ........ ........ ........ ........ .... Stokes shift........ 114

1.Light Emission

1.There are different processes that can lead to the emission of light. Incandescence refers to the process of emission of electromagnetic radiation from a hot body as a result of its temperature, also known as 'black body radiation'. Luminescence refers to the process of emission of electromagnetic radiation when the excitation process involves high energy photons, fast electrons, a chemical reaction or another mechanism different to black body radiation.

2.Photons are the elementary particles of electromagnetic radiation. Electromagnetic radiation is the technical name for the energy that is propagated by waves of electromagnetic fields.  Electromagnetic radiation covers photon energies that are very high and have very short wavelengths such as x-rays, down to low energies in the form of microwaves and radio waves which have very long wavelengths. 

3.The term light is often used to refer to electromagnetic radiation of energies (or wavelengths) that are visible to humans, and those adjacent to them (ultraviolet and infrared wavelengths).

4.Processes that can result in luminescence include bombardment by high energy electron beams (cathodoluminescence), electrical energy (electroluminescence), chemical reactions (chemiluminescence) and the absorption of photons (photoluminescence).

5.Photoluminescence is light (photon) emission after the absorption of photons (termed photoexcitation or excitation).

6.Common sources of luminescence are the relaxation transitions of excited electrons in atoms, ions or molecules. Electrons present in atoms, ions or molecules may exist in different energy states. The lowest energy state is termed the ground state. Higher energy states are referred to as excited states. In photoluminescence, when a photon is absorbed, the electron configuration is excited to a higher energy state. This is often referred to as an excited state.

7.Electrons can return to the ground state through different processes, the emission of light (that is, photons) is only one of these. There are different quantum mechanical pathways through which the electron may return to its ground state and light may be emitted, or the excited state energy may be dissipated as heat but no light is emitted.

8.In semiconductor materials, absorption of a photon may create a pair of negative and positive charge carriers that are electrons and holes, respectively.  Recombination of an electron-hole pair may result in emission of light.  Electrons and holes in semiconductors may be mobile and thus the energy of an absorbed photon may be distributed around a region, rather than confined to a single atom, ion or molecule.

1A.    Diode

9.A diode is an electronic component with two terminals. Most electronic diodes are made with semiconductor materials.

10.Diodes have low resistance to electrical current in one direction (the forward direction) and high resistance in the other direction (the reverse direction). In effect, this means they conduct electrical current predominantly in only one direction (the forward direction).

11.A light emitting diode, or LED, is a particular design of a diode where a portion of the forward current gets turned into light emission (see section 2 'light emitting diode'). This is achieved by the particular design of the semiconductor materials of the diode. Not all semiconductor diodes are LEDs.

2.Light Emitting Diode

12.Semiconductor materials have electrical conductivity between electrical insulators and conductors and are frequently used in electrically powered devices. Some of these semiconductor devices produce luminescence from the recombination of electrical charges in a diode (electroluminescence). These types of semiconductor devices are referred to as light emitting diodes or LEDs.

13.Semiconductors can be doped with specifically chosen atoms to tailor their electrical conductivity to be either p-type or n-type. In p-type material the electrical carrier is positively charged (called holes); in n-type it is negatively charged (called electrons).

14.The structure of an LED is commonly fabricated from the joining of a p-type semiconductor and an n-type semiconductor. The region where these two types meet is called the junction region (or, a p-n junction).

15.Light is most commonly emitted from an LED when electrons in the conduction band recombine with holes in the valence band. This recombination process occurs in the region of the junction. The electrons and holes are supplied from an electrical power source.

16.Electrical current flow, and thus light output, can only occur in an LED when the external power source is applied with the correct polarity (negative pole to n-type side, positive pole to p-type side).  This is called forward bias polarity.  In forward bias polarity the electrons from the power source are injected in the n-type side of the junction region.  In reverse bias polarity, the negative pole of the power source is connected to the p-type side of the diode that is not conducting electrons, meaning no electrical current flow (and thus light output) can occur.

17.The relationships between light output, electrical current, applied voltage and applied polarity are distinctive features of a p-n junction, and thus a distinctive signature of the presence of p- and n-type semiconductors.

18.The spectrum of the light emitted from an LED is normally in the form of a peak or peaks at wavelengths characteristic of the semiconductor material. Refer also to section 5 ‘nitride compound semiconductor’. In addition to the material, the spectrum of the light emitted from an LED is also dependent on the structure of the LED (how its layers are arranged and what its crystal structure is).

3.Phosphor

19.A phosphor is a substance that exhibits a luminescence process when suitably excited.

20.Phosphors often have 2 components. The first is the luminescent centre (sometimes called the dopant or activator) and the second is the host matrix or host crystal lattice.

21.The activator is usually a particular element, which will often be in an ion form in the host matrix. 

22.The general role of a phosphor when used with a light emitting diode is to change the overall emission wavelengths emitted from the integrated device. The phosphor changes the overall perceived colour of light emitted by absorbing some (but not all) of the light emitted by the semiconductor chip. It achieves this by the activator absorbing photons emitted by the LED semiconductor to produce excited states of the activator.  The activator subsequently relaxes back to its original ground state by emitting photons of a different energy and hence a different colour to that absorbed.  A key requirement of the phosphor is having an activator with absorption transitions that match the LED emission, and having emission transitions at the energies corresponding to the desired new colours.

4.Absorption and emission of light at different wavelengths

23.Every different type of dopant or activator has a fingerprint that comes from the individual ways that its electrons can be excited and relax.  These transitions are called electronic transitions.

24.As mentioned in paragraph 6 an electron configuration goes to a higher energy state when light is absorbed.  The wavelength of the absorbed light is determined by the energy difference between the two states of the transition.

25.Light may be (but is not always) emitted when an electronic state transitions to a lower electronic energy state. Light is emitted when the transition to a lower state is accompanied with the emission of electromagnetic radiation (photons). Similar to absorption, the wavelength of the emitted light is determined by the energy difference between the two states of the transition.

26.Usually, though not in every case, the light emitted is of a different wavelength to the light absorbed.

27.Light is not always emitted when there is a downwards transition.  For example, the downwards transition may be in the form of heat, which is known as a nonradiative transition. The host matrix can have a role in determining the probability of light emission versus nonradiative transitions.

28.Light emission can be measured in an emission spectrum which can be represented as a graph of light intensity versus wavelength.

5.Nitride compound semiconductor

29.Compound semiconductors comprise two or more elements. The precise ratios of elements must remain uniform throughout the compound semiconductor.  A particular compound can be a semiconductor even when the constituent elements are not.

30.A nitride compound semiconductor is linked to the family known as the group-III nitrides. 

31.Aluminium (Al), gallium (Ga) and indium (In) are metal elements from group-III of the Periodic Table.  They have similar but not identical chemical properties.

32.The nitride compound semiconductors form when Al, Ga, or In chemically bond to N in an approximate 1:1 ratio to form a crystal structure that has semiconducting properties. 

33.In addition to the 3 binary compounds (AlN, GaN, InN), mixtures can be made. For example, In_xGa_1-xN is a nitride compound semiconductor, being a mixture of InN and GaN where the ratio of InN and GaN is determined by ‘x’. GaN LEDs can emit blue light.

6.Garnet

34.Garnet is a general classification name for a class of natural gemstones that have oxygen forming tetrahedra with silicon (Si) at the centre.  The general chemical formula for a natural garnet is X₃Z₂(SiO₄)₃.

35.In addition to natural garnets, a number of synthetic garnets have been fabricated following the same general chemical formula given above.  One such synthetic garnet is YAG - an acronym for yttrium aluminium garnet.  YAG is represented by the chemical formula Y₃Al₅O₁₂ which can be written in the general garnet formula as Y₃Al₂(AlO₄)₃.

36.Garnets are crystalline materials. This means the elements in the garnet structure have a periodic arrangement. At the heart of a crystal structure is a single unit cell that represents the repeating pattern of the crystal.  For the garnet structure the underlying unit cell is a cube that contains 8 formula units of X₃Z₂(SiO₄)₃. Thus the garnet crystal structure has a unit cell containing 160 atoms.

7.Fluorescence

37.Fluorescence refers to a photoluminescence process in which a photon (electromagnetic radiation) is absorbed by a substance (for example an atom, ion or molecule) and a photon (electromagnetic radiation) is emitted from that substance. The wavelength of the emitted photon is usually longer than the wavelength of the absorbed photon, and the emission of light ceases immediately upon removal of the excitation source.

38.Luminescence can be divided into fluorescence and phosphorescence. In fluorescence, emission is an immediate process involving a spin-allowed transition. This differs from phosphorescence, which involves a spin-forbidden transition and has a longer life time, sometimes visible as afterglow.

39.At a basic level, a phosphorescent material will continue to emit light for a period of time after the excitation source is removed, whereas a fluorescent material will stop emitting light almost immediately after the excitation source is removed. In other words, a phosphorescent material has a long decay time, whereas a fluorescent material has a short decay time. Both are materials that absorb light of one wavelength and emit light of a different wavelength.

8.Activation

40.In order to act as a phosphor, a material is required to emit light when suitably excited.  In general, the host matrix of a phosphor does not absorb and emit light and thus cannot act as a phosphor until it is “activated” by a suitable substance.  The activator is deliberately chosen to have absorption and emission of light with photon energies required for the application.  In general the activator does not influence the host matrix as it is included at low concentrations and is also chemically compatible with atoms of the host matrix.

41.The wavelengths of electronic transitions (see explanation in section 4) of activator atoms or ions is influenced by the host matrix.

42.The exact distance to, and bonding of, host matrix atoms or ions with the activator influences the energy levels of the activator.

43.The specific nature of atoms or ions of the host matrix influences the electronic energy levels of the activator.

44.Therefore, even for the same activator (for example cerium (Ce)), the exact wavelengths of absorption and emission change with different host matrixes.

45.The corollary is that all examples of the same host matrix and activator combination will exhibit the same wavelengths of absorption and emission, provided that the concentration of the activator is the same. Different concentrations of the activator can shift the wavelengths of absorption and emission, even with the same host matrix.

9.The general formula of claim 3

9.1Structure of the general formula of claim 3

46.Claim 3 recites “fluorescent material represented by a general formula (Re_1-rSm_r)₃(Al_1-sGa_s)₅O₁₂ :Ce, where 0 ≤ r < 1 and 0 ≤ s ≤ 1 and Re is at least one selected from Y and Gd” (General Formula). 

47.The General Formula represents a general description of the composition of a synthetic garnet structure. The formula unit identifies the ratio of oxygen ions to metal ions identified by “(Re_1-rSm_r)” to metal ions identified by “(Al_1-sGa_s)”, being a ratio of 12 to 3 to 5.

48.The terminology of writing ":Ce" on the end is notation for cerium being a dopant replacing part of the Re ion in the matrix.

49.This formula represents a cerium-activated phosphor with a garnet structure.

50.In chemical notation:

(a)Y represents the element yttrium,

(b)Gd represents the element gadolinium,

(c)Sm represents the element samarium,

(d)Al represents the element aluminium,

(e)Ga represents the element gallium,

(f)O represents the element oxygen, and

(g)Ce represents the element cerium.

51.The General Formula includes (Al_1-sGa_s)₅  where 0 ≤ s ≤ 1. The parameter s describes the fraction of Ga present, e.g. s = 0.2 would mean 20 out of every 100 of (Al + Ga) would be Ga. The parameter s can be 0 or 1. This means that the formula covers the possibility of having only aluminium (and no gallium), or only gallium (and no aluminium) present in material represented by the formula.

52.The General Formula includes (Re_1-rSm_r)₃ where 0 ≤ r < 1 and Re is at least one selected from Y or Gd.  The parameter r represents the fraction of samarium present. It is indicated that r must be less than, and cannot be equal to, 1. As r cannot equal 1:

(a)material represented by the General Formula cannot contain only samarium, that is, crystals represented by the formula Sm₃(Al_1-sGa_s)₅O₁₂, are not included in this formula.

(b)there must always be some atoms of either Y or Gd (or both) present in material represented by the formula.

53.The inclusion of the words 'at least one' implies that both Y and Gd can be present. This means that possible combinations of elements represented by this portion of the General Formula are:

(a)Y,

(b)Gd,

(c)Y and Gd,

(d)Y and Sm,

(e)Gd and Sm, and

(f)Y, Gd and Sm.

9.2Y₃Al₅O₁₂:Ce

54.An example of a material represented by the General Formula is Y₃Al₅O₁₂:Ce. This material may be identified as YAG:Ce.

55.Ce can be called the activator of the YAG:Ce phosphor.

56.YAG:Ce can absorb specific wavelengths of light that correspond to exciting cerium electrons to higher energy states. One wavelength for absorption in YAG:Ce is blue light of 450 nanometres. A nanometre (nm) is a unit of length that is 10^-9 metre, or one billionth of a metre.

57.After being excited by this absorption process, the cerium electrons return to lower energy states by the complementary process of light emission (photoluminescence).  This emitted light has a different wavelength than the absorbed light.

58.When YAG:Ce is excited by blue light, the phosphor emits an emission band that spans the wavelength range from around 500 to 700 nm. The human eye perceives this phosphor emission as yellow light, which can, when combined with blue light emitted by the LED, make the total light emitted appear to the eye as white light.  Refer to section 10 for further information.

59.The diagram below illustrates how this works. Blue light at 450 nm enters the YAG:Ce phosphor, is absorbed, and yellow light is emitted.  As the absorption by the phosphor is less than 100%, some 450 nm blue light is also transmitted through and around the phosphor.

60.The totality of the blue LED light exiting the device that is transmitted (the part not absorbed by the phosphor), and light in the wavelength range from around 500 to 700 nm from emission of the phosphor, constitute the white light emission of the device.

10.Visible light

61.Light that is capable of producing a visual sensation to the human eye ranges from about 360nm to about 830nm and includes all colours from red to violet. It is also common to say that the visible region of the spectrum ranges from 400nm to 700nm, as perception varies from person to person.

62.The visible region of the spectrum is bounded by the ultraviolet (UV) (<400nm) and infrared (>700nm) regions. Regions are not precisely bounded and may overlap.

63.Visible light can be either natural or artificial. Sunlight and skylight are natural forms of light. Artificial forms of light include light produced by:

(a)incandescent sources, in which light is produced by a material heated to incandescence, typically having a very broad spectrum of emitted light (e.g. tungsten filament lamps and tungsten-halogen lamps);

(b)discharge lamps, in which radiation is produced by an electric discharge in a gas, typically emitting in a number of different and distinct spectral lines which may be in the UV or the visible and those in the UV require conversion to visible light by phosphors (e.g. fluorescent lamps);

(c)solid state devices, in which light is produced by a semiconductor material, typically emitting light in a particular range of one colour (e.g. LED semiconductors); and

(d)'coherent' sources, in which light is produced within typically a very narrow spectral range (e.g. lasers).

64.The eye’s sensitivity to light varies depending on the wavelength of light. As the diagram below shows,[1] the eye is most sensitive to light with a wavelength of around 555 nm, and the sensitivity to light drops off on either side of this maximum.

[1] Figure 1.2, from Bergh AA & Dean PJ, Light emitting diodes, 1976, Clarendon Press, Oxford.

65.White light is a combination of other colours of visible light. It is a perception by the human eye of light when each of the three types of cone cells in the eye is similarly stimulated. Perceiving white light thus requires the presence of at least two different wavelengths of light.

66.Various colours of visible light can be combined to produce white light. For example:

(a)     red, green and blue; and

(b)     blue  and yellow.

67.Based on the principles of colorimetry, every colour other than a primary colour can be realised by mixing two primary colours. The colours can be presented in a colour triangle known as a chromaticity diagram. The most widely used diagram is the one standardised in 1931 by the Commission Internationale d’Eclairage and is known as the CIE chromaticity diagram. With this diagram colours are defined by the colour coordinates x and y. From the emission spectrum of a light source the coordinates x and y can be determined and provide a quantitative representation of the colour.

68.In the diagram below,[2] all possible colours of light are enclosed by a curved line representing saturated or 'pure' colours (single wavelength, in nm) of the electromagnetic spectrum and a line connecting the x and y coordinates for the extreme violet and extreme red.

[2] Figure 1.5, from Bergh AA & Dean PJ, Light emitting diodes, 1976, Clarendon Press, Oxford.

69.Colours lying on the black-body locus (or Planckian locus) (which is the path or locus that the colour of an incandescent black-body radiator would take if it was heated) are typically considered to be white. A black-body radiator is an ‘ideal body’ that absorbs all incident electromagnetic radiation and, when heated, emits a broad spectrum of electromagnetic radiation with a colour that changes from red to yellow to white to bluish white as the temperature increases. It is the reference by which the whiteness of other light sources can be assessed. Typically, when the temperature of a black-body radiator is more than 2,500 Kelvin (K), it is considered white.

70.The colour ‘white’ is itself very difficult to define.  Its definition depends on the application of the light source (e.g., in some fields, white is defined for applications in that field) and the adaptive state of the human eye (e.g., an incandescent house light will be perceived as a different hue of white when viewed indoors as opposed to outside under natural light). 

11.Thermal quenching

71.When an ion has been excited to a high energy state it can return to the ground state by emitting light (the desired process in phosphors, called 'radiative decay') or it can return to the ground state by giving off the excess energy in the form of heat (undesired in phosphors, called 'non-radiative decay').

72.There are different mechanisms for non-radiative decay and typically they are thermally activated, which means that they require heat (high temperatures) to occur. The temperature at which the probabilities for radiative decay and non-radiative decay are equal is called the 'quenching temperature'. At this temperature, only half of the excited ions in a luminescent material emit light and the quantum efficiency of the luminescent material, defined as the number of photons (light particles) emitted divided by the number of photons absorbed, is 50%.

73.The quenching temperature for a specific luminescent material depends on many factors and is often not well understood. For example, it can depend on the type of luminescent ion, the type and exact chemical composition of the host material in which the luminescent ion is embedded, the concentration of the luminescent ion, the procedure for synthesising the luminescent material, the presence of impurity ions, and so on.

74.As a luminescent material reaches its quenching temperature, it starts to suffer from 'thermal quenching' and its emission intensity starts to decrease.  Thermal quenching is a reversible process: once the material cools, its efficiency returns to its original level.

75.Thermal quenching is a common phenomenon in luminescent materials, and is caused by the opening up of non-radiative pathways for a luminescent ion to return to the ground state without emitting a photon at certain temperatures.

76.Thermal quenching is also known as 'temperature quenching' or 'luminescence temperature quenching'.

12.Stokes shift

77.There can be Stokes phosphors and anti-Stokes phosphors.

78.A Stokes phosphor absorbs light of a short wavelength and emits light of a longer wavelength. A Stokes phosphor can also be referred to as a down-converting or a down-shifting phosphor because photon energy goes down.

79.An anti-Stokes phosphor absorbs light of a long wavelength and emits light of a shorter wavelength. Anti-Stokes phosphors, or up-converting phosphors, are not as efficient as Stokes phosphors (as more than one photon must be absorbed for each photon emitted and the process of up-conversion has more inherent loss mechanisms).

80.The Stokes shift is the energy difference between the maximum of the excitation band and the emission band of the same electronic transition.