Petition for Inter Partes Review of USP 7,907,137
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`IN THE UNITED STATES PATENT AND TRADEMARK OFFICE
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`In re Inter Partes Review of:
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`U.S. Patent No. 7,907,137
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`Issued: March 15, 2011
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`Application No.: 11/391,941
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`Filing Date: March 29, 2006
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`For: Display Drive Apparatus, Display Apparatus and Drive Control Method
`Thereof
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`FILED VIA E2E
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`
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`PETITION FOR INTER PARTES REVIEW
`OF U.S. PATENT NO. 7,907,137
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`Petition for Inter Partes Review of USP 7,907,137
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`TABLE OF CONTENTS
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`Introduction ...................................................................................................... 1
`I.
`II. Mandatory Notices Under 37 C.F.R. § 42.8 .................................................... 1
`A.
`Real Parties-in-Interest (37 C.F.R. § 42.8(b)(1)) .................................. 1
`B.
`Related Matters (37 C.F.R. § 42.8(b)(2)) .............................................. 2
`C.
`Lead and Backup Counsel and Service Information ............................. 2
`D.
`Fee for Inter Partes Review .................................................................. 3
`III. Grounds For Standing (37 C.F.R. § 42.104(A)) .............................................. 3
`IV.
`Identification Of Challenges (37 C.F.R. § 42.104(b)) ..................................... 3
`V.
`Background ...................................................................................................... 3
`A. Overview of the ’137 Patent (Ex. 1001) ............................................... 3
`B.
`Prosecution History ............................................................................. 13
`C.
`The Person of Ordinary Skill In The Art ............................................ 14
`VI. Claim Construction ........................................................................................ 15
`VII. Claims 1, 10-11 And 36-37 Are Unpatentable Over Miyazawa, Alone
`Or With Childs. .............................................................................................. 16
`A.
`Prior Art Overview .............................................................................. 17
`1. Miyazawa (Ex. 1005) ................................................................ 17
`2.
`Childs (Ex. 1006) ...................................................................... 23
`Independent Claim 10 Is Unpatentable Over Miyazawa, Alone
`Or With Childs. ................................................................................... 27
`1.
`Preamble: operation of the display drive apparatus .................. 27
`2.
`[a] Threshold voltage detection circuit ..................................... 31
`3.
`[b] Compensation voltage application circuit ........................... 45
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`B.
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`Petition for Inter Partes Review of USP 7,907,137
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`C.
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`D.
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`4.
`[c] Gradation signal generation circuit ..................................... 50
`Independent Claim 36 Is Unpatentable Over Miyazawa, Alone
`Or With Childs. ................................................................................... 55
`Independent Claim 1 Is Unpatentable Over Miyazawa, Alone
`Or With Childs. ................................................................................... 57
`Dependent Claims 11 and 37 Are Unpatentable Over
`Miyazawa, Alone Or With Childs. ...................................................... 60
`1.
`Claim 11 .................................................................................... 61
`2.
`Claim 37 .................................................................................... 62
`VIII. Dependent Claims 9, 15 and 39 Are Unpatentable Over Miyazawa,
`Alone Or With Childs, and Kasai. ................................................................. 63
`A. Overview of Claims 9, 15 and 39 ........................................................ 63
`B.
`Overview of Kasai (Ex. 1007) ............................................................. 65
`C.
`Claims 9, 15 and 39 Are Unpatentable Over Miyazawa, Alone
`Or With Childs, and Kasai. ................................................................. 69
`IX. No Secondary Considerations ....................................................................... 74
`X.
`The Board Should Reach The Merits Of This Petition ................................. 75
`XI. Conclusion ..................................................................................................... 76
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`E.
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`Petition for Inter Partes Review of USP 7,907,137
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`TABLE OF AUTHORITIES
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` Page(s)
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`CASES
`Nidec Motor v. Zhongshan Broad Ocean Motor,
`868 F.3d 1013 (Fed. Cir. 2017) .......................................................................... 15
`Solas OLED Ltd. v. LG Display Co., Ltd. et al.,
`No. 6:19-cv-00236-ADA ...................................................................................... 2
`STATUTES
`35 U.S.C. § 103 .......................................................................................................... 3
`35 U.S.C. § 314 ........................................................................................................ 75
`REGULATIONS
`37 C.F.R. § 42.8 ......................................................................................................... 1
`37 C.F.R. § 42.8(b)(1) ................................................................................................ 1
`37 C.F.R. § 42.8(b)(2) ................................................................................................ 2
`37 C.F.R. § 42.8(b)(3) ................................................................................................ 2
`37 C.F.R. § 42.8(b)(4) ................................................................................................ 2
`37 C.F.R. § 42.10(a) ................................................................................................... 2
`37 C.F.R. § 42.10(b) .................................................................................................. 3
`37 C.F.R. § 42.15(a) ................................................................................................... 3
`37 C.F.R. § 42.104(A)................................................................................................ 3
`37 C.F.R. § 42.104(b) ................................................................................................ 3
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`Petition for Inter Partes Review of USP 7,907,137
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`Exhibit List
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`Description
`Ex.
`1001 U.S. Patent No. 7,907,137 (“’137 Patent”)
`1002 Prosecution history for U.S. Patent Application 11/391,941 (“’137 FH”)
`
`1003 Declaration of Miltiadis K. Hatalis, Ph.D., in Support of Petitioner’s
`Request for Inter Partes Review (“Hatalis”)
`1004 Curriculum Vitae of Miltiadis K. Hatalis, Ph.D.
`1005 U.S. Patent Application Publication No. 2005/0116902 (“Miyazawa”)
`1006
`International Patent Application Publication No. WO 2005/069267
`(“Childs”)
`1007 U.S. Patent Application Publication No. 2005/0156837 (“Kasai”)
`1008 A. Ortiz-Conde, et. al., A Review of Recent MOSFET Threshold Voltage
`Extraction Methods, 583 Microelectronics Reliability 42 (2002) (“Ortiz-
`Conde”)
`1009 Solas's Opening Claim Construction Brief, Solas OLED Ltd. v. LG
`Display Co., Ltd., et al., Case No. 6:19-cv-00236-ADA, Dkt. 68 (W.D.
`Tex. Mar. 13, 2020) (“Solas's Op. Claim Construction Br.”)
`1010 Defendants' Opening Claim Construction Brief, Solas OLED Ltd. v. LG
`Display Co., Ltd., et al., Case No. 6:19-cv-00236-ADA, Dkt. 67 (W.D.
`Tex. Mar. 13, 2020) (“Defendants' Op. Claim Construction Br.”)
`1011 U.S. Patent Application Publication No. 2002/0101172 (“Bu”)
`1012 Excerpts from Neil H.E. Weste & Kamran Eshraghian, Principles of
`CMOS VLSI Design (2nd Ed. 1993) (“Weste”)
`1013 Answer and Counterclaims of Defendant LG Display Co., Ltd. to
`Plaintiff’s Second Amended Complaint, Solas OLED Ltd. v. LG Display
`Co., Ltd., et al., Case No. 6:19-cv-00236-ADA, Dkt. 41 (W.D. Tex. Oct.
`28, 2019) (“Answer”)
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`Petition for Inter Partes Review of USP 7,907,137
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`Description
`Ex.
`1014 UK Patent Application No. 2,389,952 (“Routley”)
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`1015 U.S. Patent No. 6,809,706 (“Shimoda”)
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`1016 U.S. Patent No. 8,115,707 (“Nathan”)
`1017 Excerpts from Transcript of Telephonic Markman Hearing before the
`Honorable Alan. D. Albright, Solas OLED Ltd. v. LG Display Co., Ltd.,
`et al., Case No. 6:19-cv-00236-ADA (W.D. Tex. May 22, 2020)
`(“Markman Hearing Transcript”)
`1018 U.S. Patent No. 7,576,718 (“Miyazawa-718”)
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`1019 U.S. Patent Application Publication No. 2005/0067971 (“Kane”)
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`I.
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`Petition for Inter Partes Review of USP 7,907,137
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`Introduction
`LG Display Co., Ltd. (“LG Display” or “Petitioner”) requests inter partes
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`review of claims 1, 9, 10, 11, 15, 36, 37, and 39 of U. S. Pat. No. 7,907,137 (“the
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`’137 patent”) (Ex. 1001).
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`The ’137 patent recognizes that, due to manufacturing differences, use, and
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`age, the driving transistors in a display’s pixels may have somewhat different
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`threshold voltages, which reduces display quality. Id., 3:15-42. To address this
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`problem, the ’137 patent proposes detecting and compensating for each driving
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`transistor’s particular threshold voltage. Id., 3:45-65.
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`However, the prior art already recognized and solved this problem in the same
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`way. Miyazawa (Ex. 1005), for example, recognized the same problem and solved
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`it using the method and apparatus recited in the challenged claims. Further, Childs
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`(Ex. 1006) teaches detecting threshold voltages in pixels the same way described by
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`the ’137 patent, but not recited in the challenged claims.
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`Accordingly, the Board should institute review of the ’137 patent’s challenged
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`claims and find them unpatentable.
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`II. Mandatory Notices Under 37 C.F.R. § 42.8
`A. Real Parties-in-Interest (37 C.F.R. § 42.8(b)(1))
`The real party-in-interest is Petitioner LG Display.
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`B. Related Matters (37 C.F.R. § 42.8(b)(2))
`The ’137 patent has been asserted in the following district court case pending
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`in the Western District of Texas: Solas OLED Ltd. v. LG Display Co., Ltd. et al., No.
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`6:19-cv-00236-ADA.
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`C. Lead and Backup Counsel and Service Information
`Under 37 C.F.R. §§ 42.8(b)(3), 42.8(b)(4), and 42.10(a), Petitioner
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`designates the following lead counsel:
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`• Jonathan M. Strang (Reg. No. 61,724), jonathan.strang@lw.com,
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`Latham & Watkins LLP; 555 Eleventh Street, NW, Ste. 1000;
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`Washington, DC 20004-1304; 202.637.2362 (Tel.); 202.637.2201
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`(Fax).
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`Petitioner also designates the following backup counsel:
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`• Gabriel S. Gross (Reg. No. 52,973), gabe.gross@lw.com, Latham &
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`Watkins LLP; 140 Scott Drive, Menlo Park, CA 94025; 650.463.2628
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`(Tel.); 650.463.2600 (Fax).
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`• Douglas E. Lumish
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`(Pro hac vice motion
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`to be
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`filed),
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`doug.lumish@lw.com, Latham & Watkins LLP; 140 Scott Drive,
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`Menlo Park, CA 94025; 650.463.2633 (Tel.); 650.463.2600 (Fax).
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`• Joseph H. Lee (Pro hac vice motion to be filed), joseph.lee@lw.com,
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`Latham & Watkins LLP; 650 Town Center Drive, 20th Floor, Costa
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`Petition for Inter Partes Review of USP 7,907,137
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`Mesa, CA 92626-1925; 714.755.8046 (Tel.); 714.755.8290 (Fax).
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`• Blake R. Davis (Pro hac vice motion to be filed), blake.davis@lw.com;
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`Latham & Watkins LLP; 505 Montgomery Street, Suite 2000, San
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`Francisco, CA 94111-6538; 415.395.8033 (Tel.); 415.395.8095 (Fax).
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`Pursuant to 37 C.F.R. § 42.10(b), a Power of Attorney from Petitioner is attached.
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`LG Display consents to electronic service.
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`D.
`Fee for Inter Partes Review
`The Director is authorized to charge the fee specified by 37 C.F.R. § 42.15(a)
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`to Deposit Account No. 506269.
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`III. Grounds For Standing (37 C.F.R. § 42.104(A))
`Petitioner certifies that the ’137 patent is available for IPR and that Petitioner
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`is eligible to request IPR of the ’137 patent.
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`IV.
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`Identification Of Challenges (37 C.F.R. § 42.104(b))
`• Claims 1, 10, 11, 36 and 37 are unpatentable under 35 U.S.C. § 103 over
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`Miyazawa (Ex. 1005), alone or with Childs (Ex. 1006).
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`• Claims 9, 15 and 39 are unpatentable under 35 U.S.C. § 103 over
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`Miyazawa, alone or with Childs, and Kasai (Ex. 1007).
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`V. Background
`A. Overview of the ’137 Patent (Ex. 1001)
`The ’137 patent is directed to an active matrix display drive (e.g., for
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`computing devices, mobile phones, etc.) that “detects a threshold voltage peculiar to
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`the drive element of the display pixel, and a compensation voltage application circuit
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`which generates a compensation voltage for compensating for the threshold voltage
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`of the drive element on the basis of the threshold voltage and applies the
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`compensation voltage to the drive element.” ’137 patent, Abstract, 1:15-58.
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`In an active matrix display there are a plurality of pixels arranged in a matrix,
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`each having its own organic electroluminescent element (or OEL, also referred to as
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`an organic light emitting diode or OLED). Each OEL in turn has its own “drive
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`circuit” that is used to control the amount of current provided to the OEL, which
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`determines how much light it emits. See, e.g., id., Fig. 19 (showing exemplary high
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`level block diagram of a display).
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`The ’137 patent states that prior-art displays failed to compensate for
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`differences between the pixels’ drive transistors, which are the drive circuit elements
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`that principally control the amount of current supplied to each OEL. As the patent
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`explains, the “threshold voltage characteristics” of the drive transistor “may change
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`(shift) depending on the usage time, the drive history and the like[,]” as well as
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`manufacturing differences. Id., 3:15-42. These changes and inconsistencies among
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`the drive transistors can lead to non-uniform illumination of the OELs, and so of the
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`pixels, in the display. Hatalis (Ex. 1003) ¶¶ 36-39, 59.
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`The ’137 patent proposes that the drive circuits of the purported invention use
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`a “known” drive control method referred to as a “current gradation specification
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`mode (or, a current gradation specification drive).” Id., 20:27-42; Hatalis ¶¶ 52-54
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`(explaining that current gradation specification modes are also known to a POSA as
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`“current programmed” pixel circuits). In this mode, the light emitting operation of
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`each OEL is controlled by “directly flowing a current component (a gradation
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`current) of a gradation signal corresponding to display data via a data line DL
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`toward[s] a drive circuit DC provided on a display pixel PX.” ’137 patent, 20:31-
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`42, 24:2-60. The current gradation specification drive pixel circuit of the ’137 patent
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`is shown below:
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`Hatalis ¶ 56 (annotating ’137 patent, Fig. 9); ’137 patent, 21:62-23:9, claims 10, 36.
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`As shown, in each pixel (“PX”) there is a drive circuit (“DC”) which has three
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`transistors (“Tr11,” “Tr12,” and “Tr13,”) a capacitor (“Cs”), and a current controlled
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`optical element (“OEL”). Hatalis ¶ 53-54. The amount of driving current that will
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`be “allowed to flow in the OEL” during a light emitting operation is set directly by
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`a “gradation current” (“Idata”) that is provided through the data line (“DL”), as
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`shown in the solid black arrow ending at the “gradation signal generation unit 130”
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`in the upper right hand corner in the figure above. ’137 patent, 22:8-14; Hatalis ¶¶
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`57-58.
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`The current has a “negative polarity” meaning that it flows in the direction
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`away from the display pixel towards the data line. Id.; Hatalis ¶ 56. When the
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`gradation current is provided, it “forcedly” turns the drive transistor (Tr13) on so
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`that the gradation current flows “between the drain and source of the thin film
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`transistor Tr13[.]” ’137 patent, 24:23-30. The drive transistor, Tr13, is used to
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`perform a “current-voltage conversion function” to store a voltage on the capacitor,
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`Cs, that would allow Tr13 to provide a driving current during a light emitting
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`operation. Id., 24:37-44; see also id. 24:8-10 (“the driving current Iem which flows
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`in the organic EL element OEL has a current value (Iems≈Iwrt=Idata) which is equal
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`to the writing current Iwrt (the gradation current Idata)”); Hatalis ¶ 57-58.
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`The ’137 patent recognized a purported problem with current programmed
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`pixels where, at low gradation currents corresponding to low light emitting levels or
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`“luminance gradations,” it takes too much time for the gradation current flowing
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`through the drive transistor to charge a corresponding voltage on the capacitor. ’137
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`patent, 20:42-53. As a result, “a writing insufficiency is generated in which the
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`voltage component held in between the gate and the source of the thin film transistor
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`Tr13 (the both ends of the capacitor Cs) becomes insufficient with respect to the
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`display data.” Id.; Hatalis ¶¶ 59-61.
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`The ’137 patent seeks to solve this problem by pre-charging the drive
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`transistor, and so “compensating for change and variation in the element
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`characteristics of the drive element and providing a favorable and uniform display
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`image quality.” ’137 patent, 3:45-53. To achieve this uniformity, the patent claims
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`a circuit that “detect[s] a threshold voltage peculiar to” the pixel’s drive transistor,
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`and generates and applies “a compensation voltage for compensating for the
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`threshold voltage of the drive element on the basis of the threshold voltage[.]” ’137
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`patent, 3:45-65, 9:69-10:20; Hatalis ¶ 62.
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`The threshold compensation voltage is referred to throughout the ’137 patent
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`as a “pre-charge voltage Vpre” because it is a voltage that accelerates the charging
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`or discharging of the capacitor Cs between the gate and source of the drive transistor
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`so that, before applying the gradation current, the voltage on the capacitor Cs is set
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`to the threshold voltage peculiar to the drive transistor. See, e.g., ’137 patent, 19:58-
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`20:15 (describing “Pre-Charge Period” where the “pre-charge voltage Vpre [] is
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`output from the compensation voltage DAC 150” to the data line). Then, when the
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`gradation current is supplied, fewer electric charges need to be added to the capacitor
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`based on the gradation current because the capacitor already holds the voltage
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`component corresponding to the threshold voltage Vth. Id., 21:37-22:64. Put simply,
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`without precharge, the gradation current must charge the capacitor to a voltage
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`Vth+Vdata, whereas with precharge the gradation current charges only the
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`component Vdata. Hatalis ¶¶ 65-66. As a result, the “electric charges may be the
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`gradation current Idata (the writing current Iwrt) having a current value for charging
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`only the effective voltage Vdata for providing a gradation display in accordance with
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`the display data, and the electric charges may be charged in between the gate and the
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`source of the thin film transistor Tr13 in a relatively short time.” Id., 22:42-58.
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`To explain in more detail, the ’137 patent first detects the threshold voltage of
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`a pixel’s driving transistor by measuring the voltage at one end of the capacitor (Cs),
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`through the data line (shown below as a solid blue line), and after the capacitor is
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`charged to hold the drive transistor’s (Tr13) threshold voltage (shaded below in light
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`blue).
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` ’137 patent, Fig. 5 (cropped, annotated), 14:1-18:46, Figs. 2-6; Hatalis ¶¶ 63-64.
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`Next, the ’137 patent describes applying a compensation voltage (“precharge
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`voltage Vpre”) through the data line (solid blue line in the figure below) that is based
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`on the detected threshold voltage for that pixel. The precharge voltage is used to set
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`the gate-source voltage of the drive transistor, stored on the capacitor Cs, to the
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`detected threshold voltage for that pixel.
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`’137 patent, Fig. 8 (cropped, annotated), 18:46-21:61, Figs. 7-8; Hatalis ¶¶ 65-66.
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`The pixel is then programmed with a gradation signal that is a current with a
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`current value corresponding to display data and which is supplied through the data
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`line. The gradation current corresponds to display data for setting the pixel’s OEL
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`to a predetermined light emitting state. As discussed above, the gradation current
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`forcibly flows between the drain and source of the driving transistor which increases
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`the charge on the capacitor so that it reflects the desired level (or gradation) of light
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`plus the driving transistor’s threshold voltage.
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` ’137 patent, Fig. 9 (cropped, annotated), 21:62-23:9, claims 10, 36; Hatalis ¶¶ 67-
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`69.
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`Thus, the voltage of the driving transistor is set such that, during a light
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`emitting operation, it conducts the same amount of current as the gradation current
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`and thus the OEL emits the desired “luminance gradation,” i.e., the desired light
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`emitting level corresponding to the display data.
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` ’137 patent, Fig. 10 (cropped, annotated), 23:10-25:27; Hatalis ¶ 70.
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`B.
`Prosecution History
`During prosecution, the Examiner rejected the then-pending claims as
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`anticipated by “Ono,” a patent publication. ’137 FH (Ex. 1002), 0150-167 (May 24,
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`2010, Office Action).
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`In response, Applicant narrowed the independent claims to (i) limit the recited
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`“gradation signal” to a “gradation current having a current value,” and (ii) require
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`supplying the gradation current, detecting a threshold voltage, and supplying a
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`compensation voltage “through the data line[.]” Id., 0047 (emphasis added)
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`(pending claim 1/issued claim 10), 16 (pending claim 30/issued claim 36). Applicant
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`then contended that Ono lacked these features. Id. 0075-78 (distinguishing Ono);
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`Hatalis ¶¶ 73-79.
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`C. The Person of Ordinary Skill In The Art
`A POSA at the time of the purported invention (the 2005 timeframe) would
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`have had at least a bachelor’s degree in electrical engineering (or equivalent) and at
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`least two years’ industry experience, or equivalent experience, in circuit design or
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`related fields. Alternatively, a POSA could substitute directly relevant additional
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`education for experience, e.g., an advanced degree relating to the design of
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`electroluminescent devices, drive circuits, or other circuit design or an advanced
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`degree in electrical engineering (or equivalent), with at least one year of industry
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`experience in a related field. Hatalis ¶ 33.
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`In the District Court, Patent Owner alleges a POSA would be a person with a
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`bachelor’s degree in physics, electrical engineering, or a related field with
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`approximately 3–5 years of experience in active-matrix and/or LED displays and
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`systems, or a postgraduate degree such as a master’s degree in physics, electrical
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`engineering, or a related field with approximately 1–2 years of experience in active-
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`matrix and/or LED displays.
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`Petition for Inter Partes Review of USP 7,907,137
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`Under both definitions, the claims are unpatentable. Hatalis ¶¶ 32-34.
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`Moreover, this Petition does not turn on the precise definitions above and the claims
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`are unpatentable from the perspective of any reasonable POSA. Id. ¶ 35.
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`VI. Claim Construction
`Terms of claims subject to IPR are to be construed using the same claim
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`construction standard as district court. §42.100(b). Only terms necessary to resolve
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`the controversy need to be construed. Nidec Motor v. Zhongshan Broad Ocean
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`Motor, 868 F.3d 1013, 1017 (Fed. Cir. 2017).
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`The parties proposed competing constructions of certain terms in the co-
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`pending litigation. Solas’s Op. Claim Construction Br. (Ex. 1009); Defendants' Op.
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`Claim Construction Br. (Ex. 1010). On May 22, 2020, a Markman hearing was held
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`and during that hearing the district court entered final constructions of certain terms
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`of the ’137 patent, including a construction of “gradation current having a current
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`value” that was proposed by neither party. Markman Hearing Transcript (Ex. 1017),
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`17:5-8 (construing “a gradation current having a current value,” 17:9-11 (construing
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`“gradation signal”), (finding dependent claims 15 and 39 not indefinite), 36:4-14
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`(construing “through the data line”), 37:7-9. Those claim constructions do not
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`impact the outcome of this IPR as the prior art meets each of the parties’ proposed
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`constructions and the court’s final constructions for each term. Hatalis ¶¶ 80-81.
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`For the purpose of this IPR, Petitioner conservatively applies the narrower
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`constructions it proposed in the district court litigation, which it contends are the
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`correct constructions.
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`For example, Petitioner contends in court that a “gradation current having a
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`current value” is “an actual current (not a voltage) with a value corresponding to a
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`luminance level,” and therefore proposes art herein that teaches such a gradation
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`current. Even if Patent Owner’s construction (“a current having a current value and
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`conveying information about a level”) or the court’s construction (“a current, which
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`conveys information about a level”) are correct, however, the challenged claims are
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`unpatentable under those broader constructions for the same reasons proposed
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`herein. Hatalis ¶ 81.
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`To the extent the Petition deviates from this general rule, Petitioner will point
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`out the relevant differences in the context of the claim element.
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`VII. Claims 1, 10-11 And 36-37 Are Unpatentable Over Miyazawa, Alone Or
`With Childs.
`Miyazawa teaches each and every claim element as it is recited, but uses a
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`different technique for detecting the threshold voltage (claim 10[a] in Section
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`VII.B.2 below) than described in the embodiments of the ’137 patent. Childs,
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`however, teaches that technique and, even though it is not required by the challenged
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`claims, it would have been obvious to modify Miyazawa’s teachings to use Childs’
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`faster and more accurate technique.
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`Petition for Inter Partes Review of USP 7,907,137
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`A.
`Prior Art Overview
`The examiner did not discuss any of the following prior art in any office action.
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`1. Miyazawa (Ex. 1005)
`U.S. Publication No. 2005/0116902 to Miyazawa (“Miyazawa”) is §§ 102(a)
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`and (e) prior art because it was filed before the ’137 patent’s earliest claimed priority
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`date and published before its actual filing date.
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`Like the ’137 patent, Miyazawa is directed to improving current programmed
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`pixel circuits, and recognizes that there can be “insufficient programming” at low
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`gradation current levels due to the time it takes to charge the “voltage corresponding
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`to the current in the storage capacitor[.]” Miyazawa, [0020]; cf. ’137 patent, 20:42-
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`53 (“in the case where a light emitting operation” is performed “the writing operation
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`of the gradation signal is not completed in a predetermined time, and a writing
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`insufficiency is generated” where the voltage component held in “both ends of the
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`capacitor Cs” is insufficient”); Hatalis ¶ 83. Solving this problem in the same way
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`as the ’137 patent, Miyazawa describes that an optimal precharge voltage for each
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`pixel should be determined by detecting the threshold voltage of each pixel’s driving
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`transistor and applying a voltage that compensates for each transistor’s particular
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`threshold voltage.
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`Specifically, Miyazawa discloses a “display apparatus and method of driving
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`the same.” Miyazawa, Title. Miyazawa explains that conventional display matrixes
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`(like the one Miyazawa uses to describe Miyazawa’s improvements) were arranged
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`Petition for Inter Partes Review of USP 7,907,137
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`as shown below, with each pixel 110 including an OEL 220. Miyazawa, [0005].
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`Each pixel 110 is connected to a data line Xm (where m = 1, 2, ... M) and a scanning
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`line Yn (where n = 1, 2, 3, … N), forming a matrix with N rows and M columns of
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`pixels:
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`Hatalis ¶ 93 (annotating Miyazawa Figs. 2 and 14); Miyazawa, [0005]-[0009],
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`[0058]; see also Hatalis ¶¶ 85-92 (describing operation of Figs. 2 and 14).1 Each
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`pixel is addressed by row and column: the scan line (Yn) selects the row, and each
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`
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`1 Each pixel produces just one color (e.g., red, blue, or green). The grayscales
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`(intensities) of the emitted colors determine the perceived color and intensity at
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`normal viewing distances. Kasai (Ex. 1007), Fig. 1, [0034]-[0039]; Hatalis ¶ 86.
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`single line driver for each column may then interact with a pixel in the selected row
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`Petition for Inter Partes Review of USP 7,907,137
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`through the data line (Xm) to determine the light intensity of that pixel. Hatalis ¶ 85;
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`Miyazawa, [0058]-[0060], [0006]-[0015].
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`As illustrated above, each pixel 110 includes four transistors, 211 to 214.
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`When displaying (i.e., during “light emission period Tel”), driving transistor 214
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`controls the amount of current flowing through OEL 220, and thus the amount of
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`light it emits. Miyazawa, [0009], [0015], Fig. 15; Hatalis ¶¶ 87-90. Transistors 211
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`and 212 are “off” because gate signal V1 is “low,” and transistor 213 is “on” because
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`gate signal V2 is “high.” Miyazawa, [0015]. The amount of current flowing through
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`driving transistor 214, and thus OEL 220, is controlled by the voltage between
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`transistor 214’s gate and source—which is the voltage across capacitor 230. Id.,
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`[0015]. Thus, the pixel’s OEL 220 will emit light at an intensity determined by the
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`voltage stored in capacitor 230 and therefore applied between the source and gate of
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`driving transistor 214. Hatalis ¶¶ 91-93; Miyazawa, [0002], [0012]-[0013], [0058],
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`[0060], [0062]-[0063].
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`As shown in Figure 14 above, Miyazawa’s drive transistor 214 is a “p-
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`channel” field effect transistor (FET), and transistors 211 to 213 are “n-channel”
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`FETs. Miyazawa, [0006] (“The first to third transistors 211 to 213 are n-channel
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`field effect transistor (FET) and the fourth transistor 214 is a p-channel FET.”).2 As
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`Petition for Inter Partes Review of USP 7,907,137
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`a p-channel FET, transistor 214 conducts when the voltage at its gate is lower than
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`the voltage at its source by at least the threshold voltage, and current flows from its
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`source to its drain because its source is connected to the higher potential (i.e., Vdd).
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`Hatalis ¶¶ 90, 42, 49; Weste (Ex. 1012), 029. In contrast, n-channel transistors
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`conduct when the gate voltage is higher than source voltage by at least the threshold
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`voltage, and by convention, the drain is connected to the higher potential. Hatalis
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`¶¶ 42, 48; see also id. ¶¶ 40-51 (providing additional background on operation and
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`equations applicable
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`to n and p channel FETs); ’137 patent, 28:38-44
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`(acknowledging that, while its example uses n-channel devices, a POSA would have
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`known how to configure the circuit to use p-channel instead); Childs, 9:18-19 (“The
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`circuit above uses a p-type drive transistors [sic]. There is of course an equivalent n-
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`type implementation.”).
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`Miyazawa charges, or “programs,” capacitor 230 to the desired voltage during
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`“programming period Tpr.” Miyazawa, [0010]-[0012]. As explained earlier in this
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`section (Section VII.A.1), the voltage stored in the capacitor will determine how
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`2 Miyazawa discloses that its transistors can be thin film transistors (TFTs) or can
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`be other types of FETs, like silicon-based. Miyazawa, [0058]. The challenged
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`claims are not limited to any particular type of transistor. Hatalis ¶ 90.
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`much current flows through the transistor and OEL 220, and thus how much light is
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`Petition for Inter Partes Review of USP 7,907,137
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`emitted. Hatalis ¶¶ 92-93.
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`During this programming time, transistors 211 and 212 are on because gate
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`signal V1 is high, and transistor 213 is off because gate signal V2 is “low.”
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`Miyazawa (Ex. 1005), [0013]; Hatalis ¶¶ 89, 40-44 (providing additional
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`information regarding operation of TFTs as switches). Miyazawa explains that “data
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`line driver 140 functions as a constant current source that provides current Im
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`according to the light emission grayscale” (the desired in