Ex Parte LI et alDownload PDFPatent Trial and Appeal BoardSep 17, 201311731802 (P.T.A.B. Sep. 17, 2013) Copy Citation UNITED STATES PATENT AND TRADEMARKOFFICE UNITED STATES DEPARTMENT OF COMMERCE United States Patent and Trademark Office Address: COMMISSIONER FOR PATENTS P.O. Box 1450 Alexandria, Virginia 22313-1450 www.uspto.gov APPLICATION NO. FILING DATE FIRST NAMED INVENTOR ATTORNEY DOCKET NO. CONFIRMATION NO. 11/731,802 03/30/2007 Yi-Qun Li 318-016010US 7750 22798 7590 09/17/2013 QUINE INTELLECTUAL PROPERTY LAW GROUP, P.C. P O BOX 458 ALAMEDA, CA 94501 EXAMINER DAM, DUSTIN Q ART UNIT PAPER NUMBER 1758 MAIL DATE DELIVERY MODE 09/17/2013 PAPER Please find below and/or attached an Office communication concerning this application or proceeding. The time period for reply, if any, is set in the attached communication. PTOL-90A (Rev. 04/07) UNITED STATES PATENT AND TRADEMARK OFFICE ____________________ BEFORE THE PATENT TRIAL AND APPEAL BOARD ____________________ Ex parte YI-QUN LI, WEI SHAN, SHIFAN CHENG, and MIKE KO ____________________ Appeal 2012-001690 Application 11/731,802 Technology Center 1700 ____________________ Before CHUNG K. PAK, CATHERINE Q. TIMM, and KAREN M. HASTINGS, Administrative Patent Judges. TIMM, Administrative Patent Judge. DECISION ON APPEAL STATEMENT OF CASE Appellants appeal under 35 U.S.C. § 134 from the Examiner’s decision to reject claims 1-4, 6-12, and 15-22. We have jurisdiction under 35 U.S.C. § 6(b). For the reasons advanced by the Examiner in the Answer, we AFFIRM. We add the following for emphasis. Appeal 2012-001690 Application 11/731,802 2 The claims are directed to a photovoltaic device containing a silicate- based wavelength-converting phosphor (see, e.g., Claim 1) and a method of enhancing the conversion efficiency of a solar cell including such a phosphor (see, e.g., Claim 11). Claim 1 is illustrative of the claimed device: 1. A photovoltaic device with enhanced conversion efficiency, comprising: a solar cell for converting longer wavelength solar radiation into electrical energy; and a wavelength-converting phosphor for converting shorter wavelength solar radiation into longer wavelength radiation, the converted longer wavelength radiation substantially matched to the spectral response of the solar cell; wherein the wavelength-converting phosphor is selected from the group consisting of a silicate-based phosphor of the form M2Si04:Eu2+, and a silicate-based phosphor of the form M3SiO5:Eu2+, where M is a divalent cation. (Claims App’x at Br. 22.) The Examiner rejects the claims as listed in the Brief at page 7. To the extent Appellants argue the claims and rejections separately, we review them separately. Otherwise, we select a single claim as representative to resolve the issues on appeal. OPINION A. Claims 1 and 11 Appellants argue claims 1 and 11 as a group (Br. 8-16). We select claim 1 as representative for resolving the issues in this appeal. As pointed Appeal 2012-001690 Application 11/731,802 3 out by Appellants, the Examiner rejects claims 1, 6-12, and 21 under 35 U.S.C. § 103(a) as obvious over Tsakalakos1 in view of Srivastava2; and claims 1 and 2 under 35 U.S.C. § 103(a) as obvious over Bhattacharya3 in view of Tsakalakos in view of Srivastava and further in view of Shanks4. There is no dispute that Tsakalakos teaches a solar cell (photovoltaic (PV) cell) in combination with a wavelength-converting phosphor that functions to shift wasted ultraviolet (UV) light into the visible range (compare Br. 8-16 and Reply Br. 9-11 with Ans. 6; see also Tsakalakos, ¶ 0078). Tsakalakos suggests using a wavelength-converting phosphor that is different than the claimed phosphor, i.e., Tsakalalos suggests using a yttrium-aluminum garnet (YAG)-type phosphor (Tsakalakos, ¶ 0078). As found by the Examiner, Srivastava discloses a silicate-based phosphor of the type claimed by Appellants, i.e., a divalent europium activated alkaline earth silicate phosphor of the form M2SiO4:Eu2+ (Ans. 7; Srivastava, col. 7, ll. 20-30 (A2SiO4:Eu2+)). The Examiner concludes that it would have been obvious to one of ordinary skill in the art to use the phosphor of Srivastava in the photovoltaic deice of Tsakalakos “because a simple substitution of known elements which are also known and intended to function in the same manor, in the instant case [to] convert UV light to the visible spectrum, is a matter of obviousness in which one of ordinary skill would have expected success in the combination based on the predictable wavelength conversion properties of the phosphors.” (Ans. 7.) 1 Tsakalakos et al., US 2006/0207647 A1, pub. Sep. 21, 2006. 2 Srivastava et al., US 6,621,211 B1, patented Sep. 16, 2003. 3 Bhattacharya, US 2004/0206390 A1, pub. Oct. 21, 2004. 4 Shanks, US 5,721,462, patented Feb. 24, 1998. Appeal 2012-001690 Application 11/731,802 4 Srivastava uses the phosphor as part of a phosphor blend placed in a light emitting diode (LED) (Srivastava, col. 1, ll. 11-15). Within the LED, the phosphor converts UV light to white light (id.). Appellants contend that “since LEDs operate so differently than solar cells and the requirements of a phosphor for use with a solar cell are so different than the requirements for a phosphor for use with an LED, it would not be [sic, been] obvious to use the LED phosphor described in Srivastava in a solar cell.” (Br. 8.) In support, Appellants rely upon the Declaration of one of the Inventors, Dr. Yi-Qun Li (Br. 9-16). The issue is: Does a preponderance of the evidence support the Examiner’s finding that one would have selected the phosphor Srivastava evidences was known in the LED art for use in a solar cell on the basis of its known and predictable wavelength conversion properties? For the reasons provided by the Examiner in the Answer, we answer this question in the affirmative. Tsakalakos seeks to convert wasted UV light into the visible range and suggests using “phosphor conversion technology” to accomplish this conversion (Tsakalakos, ¶ 0078). Tsakalakos states that “[i]n some embodiments, a yttrium-aluminum-garnet (YAG)-type phosphor is used,” but Tsakalakos’ language suggests that YAG-type phosphor is only one possible embodiment. The implication is that there was a known class of phosphors that function to convert UV light into the visible range that could be used in Tsakalakos’ solar cell. Srivastava provides evidence that divalent europium activated alkaline earth silicate phosphors of the A2SiO4:Eu2+ type, with A being a divalent Appeal 2012-001690 Application 11/731,802 5 cation, were known to convert UV light into visible light (Srivastava, col. 7, ll. 5-39). Once one of ordinary skill in the art knew from the teachings of Tsakalakos that phosphors that can convert UV light into visible light could be used in solar cells to shift the wasted UV light into the visible range, it was a matter of seeking out known phosphors that perform that function for use in Tsakalakos’ solar cell. Srivastava provides evidence that the silicate- based phosphors of the claimed type were known to shift UV light into the visible range. As stated by the Supreme Court in KSR Int'l Co. v. Teleflex Inc., 550 U.S. 398, 416 (2007), “[t]he combination of familiar elements according to known methods is likely to be obvious when it does no more than yield predictable results.” On the basis that the use of the known phosphor appears to provide a predictable result, the burden shifted to Appellants to show that, in fact, the result is more than what would have been predicted by one of ordinary skill in the art. Declarant Li states that the silicate-based phosphor Appellants use “provides great advantages over the prior art use of YAG phosphor in a solar cell” (Decl., ¶ 8.) However, the fact that the excitation spectra of the claimed silicate-based phosphors are broader, more uniform, and do not suffer from the weaknesses of a phosphor like YAG:Ce as averred to by Dr. Li, does not convince us that the result was unexpected. Srivastava provides evidence that the excitation spectra, as well as other UV to visible light conversion properties, of the silicate-based phosphors in question were known and predictable (see Srivastava, col. 7, ll. 7-67 and Table 1). It appears that the selection of the phosphor is no more than selecting a known phosphor based upon the wavelength conversion properties desired in the Appeal 2012-001690 Application 11/731,802 6 solar cell. Appellants and Declarant Li have not convinced us that the “great advantages” averred to are due to a property that was previously not known or understood or due to an unexpected result occurring in the environment of a solar cell. After weighing all of the evidence of record, we determine that a preponderance of the evidence weighs in favor of the Examiner’s conclusion of obviousness. B. Claims 6, 7, and 12 Claims 6 and 12 require the phosphor have “an absorption edge at about 535 nm, and an emission maximum at about 565 nm.” Claim 7 requires the phosphor have “an emission peak full width at half maximum of about 380 me V.” The Examiner finds that because Srivastava teaches phosphors of the same components in the same concentration ranges as Appellants’ phosphors, the properties must inherently be the same as those of the claims (Ans. 7). Srivastava at column 7, lines 6-67 supports the Examiner’s finding, particularly, Table 1. Moreover, Appellants do not respond to the Examiner’s finding of inherency (Br. 16-17). Therefore, because Appellants do not dispute the finding, we sustain the Examiner’s rejection on the basis of inherency. The Examiner also determines that it would have been obvious to optimize the absorption edge wavelength, emission maximum wavelength, and emission peak full width at half maximum because Srivastava provides guidance on how to vary phosphor emission by varying the phosphor components (Ans. 8). Appeal 2012-001690 Application 11/731,802 7 Appellants contend that the optimization discussed in Srivastava is for optimizing phosphors for producing white light with desirable properties in a UV LED, and it is not realistic that Srivastava’s experimentation “would result in the use of the claimed phosphor with desirable properties in a solar cell.” (Br. 17.) Appellants’ argument does not adequately take into account the fact that Tsakalakos, the primary reference, suggests using a wavelength- converting phosphor. Part of the process of selecting a useful phosphor for converting wasted UV light to visible light as desired by Tsakalakos would have involved routine experimentation for the light conversion desired in the solar cell. Srivastava teaches how to select the alkaline earth metal component, its concentration, and how to blend it with other phosphors to obtain various light conversion properties (Srivastava, col. 4, l. 60 to col. 5, l. 7 and col. 7, ll. 20-67). The prior art as whole provides sufficient guidance for performing the routine experimentation necessary for selecting the elements, concentrations, and blends that would covert the wavelength as desired in the solar cell. A preponderance of the evidence weighs in favor of the Examiner’s conclusion of obviousness. C. Claims 15 and 21 Claim 15 is limited to a particular subset of silicate-based phosphors. Claim 21 depends from claim 15 and further requires that the phosphor include either fluorine (F) or chlorine (Cl). Appellants contend that they “cannot find an explicit rejection on these claims in the Office Action,” and that none of the cited prior art shows or makes obvious the use of a phosphor that includes F or Cl (Br. 18). Appeal 2012-001690 Application 11/731,802 8 However, the Examiner’s citation of Srivastava at column 7, lines 20- 30 was intended to support the rejection of claim 15 (Final Office Action 3 and 7; Ans. 6-7 and 10-11), and a review of column 7, lines 20-30 indicates that the phosphors of claim 15 are suggested. With regard to claim 21, the Examiner, found that Srivastava suggests including fluorine at column 7, lines 63-67, and, indeed, this portion of Srivastava does suggest that the phosphor may contain a small amount of fluorine (Final Office Action 7; Ans. 10-11). A preponderance of the evidence weighs in favor of the Examiner’s conclusion of obviousness. D. Claims 16 and 22 Claim 16 is also limited to a particular subset of silicate-based phosphorus compounds. The Examiner acknowledges that Srivastava does not explicitly disclose a phosphor of the formula of claim 16 (Ans. 11). The Examiner further applies Park5 as evidence that phosphors of the formula of claim 16 were known to convert UV light to white light. Appellants contend that “Park describes silicate based phosphors for use with LEDs, but does not describe details of the properties of these silicate based phosphors such that one skilled in the art would appreciate that these silicate based phosphors would be useful with a solar cell.” (Br. 18). However, Park describes the silicate-based phosphors as shifting the band of light (Park, ¶¶ 59-60). Given the light converting property taught by Park and the similarity of the phosphor to that of Srivastava, we determine a 5 Park et al., KR 10-0666211, patented Jan. 02, 2007 (as translated in WO 2007/035026 A1, pub. Mar. 29, 2007). Appeal 2012-001690 Application 11/731,802 9 preponderance of the evidence supports the Examiner’s conclusion of obviousness. Claim 22, like claim 21, requires the phosphor include F or Cl. As we found above, Srivastava suggests that silicate-based phosphors can contain some F. Given the similarity of the phosphors of Srivastava and Park, a preponderance of the evidence supports the Examiner’s conclusion of obviousness. E. Other Rejections of Dependent Claims Appellants do not advance any arguments directed to the other dependent claims or rejections over and above those already addressed. For the reasons advanced above, we sustain the rejection of the non-argued claims. CONCLUSION We sustain the Examiner’s rejections. DECISION The Examiner’s decision is affirmed. TIME PERIOD FOR RESPONSE No time period for taking any subsequent action in connection with this appeal may be extended under 37 C.F.R. § 1.136(a)(1). AFFIRMED cam Copy with citationCopy as parenthetical citation