`
`
`
`UNITED STATES PATENT AND TRADEMARK OFFICE
`
`_____________
`
`BEFORE THE PATENT TRIAL AND APPEAL BOARD
`
`_____________
`
`LSI CORPORATION and AVAGO TECHNOLOGIES U.S., INC.,
`
`Petitioners,
`
`v.
`
`REGENTS OF THE UNIVERSITY OF MINNESOTA,
`
`Patent Owner.
`
`_____________
`
`Case No. IPR2017-01068
`
`Patent No. 5,859,601
`
`_____________
`
`PATENT OWNER’S RESPONSE
`
`
`
`
`
`
`
`
`
`TABLE OF CONTENTS
`
`TABLE OF AUTHORITIES …………………………………………………….iii
`EXHIBIT LISTING ............................................................................................... vi
`CHALLENGED CLAIMS ………………………………………………………..x
`
`I.
`II.
`
`III.
`
`Introduction ....................................................................................................1
`Summary of the ’601 Patent ...........................................................................5
`A. HDD Basics ......................................................................................... 6
`B.
`Reading Data From a Disk .................................................................. 9
`C.
`Problem Addressed by the ’601 Patent .............................................. 13
`D.
`The Beauty of the Inventive MTR Codes of the ’601 Patent ............ 18
`Petitioners’ Invalidity Grounds and Evidence .............................................21
`A. Okada ................................................................................................. 21
`B.
`The Tsang Patent ............................................................................... 29
`C.
`Soljanin’s Testimony ......................................................................... 30
`IV. Claim Construction ......................................................................................35
`V. Okada Does Not Anticipate the Challenged Claims ....................................41
`A. Okada Does Not Disclose Every Element of Claim 13 ..................... 42
`1.
`Okada Does Not Disclose the j Constraint .............................. 42
`2.
`Okada Does Not Disclose the k Constraint ............................. 44
`Okada Does Not Disclose Every Limitation of Dependent
`Claims 14 and 17 ............................................................................... 45
`VI. The Tsang Patent Does Not Anticipate the Challenged Claims ..................46
`A.
`Factual Background ........................................................................... 47
`
`B.
`
`- i -
`
`
`
`
`
`B.
`C.
`
`Applicable Legal Principles ............................................................... 53
`The Tsang Patent Does Not Qualify as Prior Art .............................. 56
`1. Moon and Brickner Completed Their Invention Prior to
`Tsang’s Filing Date ................................................................. 56
`The Disclosure of MTR Codes in the Tsang Patent Was
`Derived From Moon and Brickner .......................................... 61
`The Tsang Patent Cannot Anticipate Under § 102(g) ....................... 65
`D.
`VII. Conclusion ...................................................................................................66
`
`
`2.
`
`
`
`- ii -
`
`
`
`
`
`TABLE OF AUTHORITIES
`
` Page(s)
`
`Cases
`AK Steel Corp. v. Sollac & Ugine,
`344 F.3d 1234 (Fed. Cir. 2003) .......................................................................... 38
`Apple Inc. v. Smartflash LLC,
`CBM2015-00028, WL 3035555, (P.T.A.B. May 26, 2016) (Paper
`44, “Final Written Decision”) ............................................................................ 33
`Apple, Inc. v. Motorola, Inc.,
`No. 1-11–cv- 8540 (N.D. Ill.) .............................................................................. 5
`Becton, Dickinson and Co. v. Baxter Corp. Englewood,
`IPR2019-00119 (May 3, 2019) ...................................................................... 4, 65
`Carnegie Mellon Univ. v. Marvell Tech. Grp., Ltd.,
`801 F.3d 1283 (Fed. Cir. 2015) .......................................................................... 10
`Cooper v. Goldfarb,
`154 F.3d 1321 (Fed. Cir. 1998) .................................................................... 54, 55
`In re DeBaun,
`687 F.2d 459 (C.C.P.A. 1982) ........................................................................... 56
`Dynamic Drinkware, LLC v. Nat’l Graphics, Inc.,
`800 F.3d 1375 (Fed. Cir. 2015) .................................................................... 41, 46
`Enzo Biochem, Inc. v. Applera Corp.,
`599 F.3d 1325 (Fed. Cir. 2010) ...................................................................... 3, 31
`EON Corp. v. Silver Spring Networks, Inc.,
`815 F.3d 1314 (Fed. Cir. 2016) .......................................................................... 37
`Green Cross Corp. v. Shire Human Genetic Therapies, Inc.,
`IPR2016-00258, 2017 WL 1096597 (P.T.A.B. Mar. 22, 2017)
`(Paper 89) ........................................................................................................... 46
`Honeywell Int’l, Inc. v. Int’l Trade Comm’n,
`341 F.3d 1332 (Fed. Cir. 2003) ...................................................................... 3, 31
`
`- iii -
`
`
`
`
`
`ICU Med., Inc. v. Alaris Med. Sys.,
`558 F.3d 1368 (Fed. Cir. 2009) .......................................................................... 38
`In re Land,
`368 F.3d 866 (C.C.P.A. 1966) ..................................................................... 55, 65
`In re Mathews,
`408 F.2d 1393 (C.C.P.A. 1969) ................................................................... 55, 65
`Ocean Innovations, Inc. v. Archer,
`145 Fed. App’x 366 (Fed. Cir. 2005) ................................................................. 38
`Perfect Surgical Tech. Inc. v. Olympus Am., Inc.,
`841 F.3d 1004 (Fed. Cir. 2016) .......................................................................... 61
`Phillips v. AWH Corp.,
`415 F.3d 1303 (Fed. Cir. 2005) (en banc) .......................................................... 37
`Power Integrations, Inc. v. Fairchild Semiconductor Int’l, Inc.,
`711 F.3d 1348 (Fed. Cir. 2013) .......................................................................... 37
`Price v. Symsek,
`988 F.2d 1187 (Fed. Cir. 1993) .................................................................... 55, 56
`Regents of the Univ. of Minn. v. LSI Corp. et al.,
`No. 5:18-cv-00821-EJD (N.D. Cal.) ........................................................ 2, 30, 31
`Renishaw PLC v. Marposs Societa’
`per Azioni, 158 F.3d 1243, 1250 (Fed. Cir. 1998) ............................................. 37
`Riverwood Int’l Corp. v. R.A. Jones & Co.,
`324 F.3d 1346 (Fed. Cir. 2003) .......................................................................... 56
`In re Robertson,
`169 F.3d 743 (Fed. Cir. 1999) ............................................................................ 41
`Scott v. Finney,
`34 F.3d 1058 (Fed. Cir. 1994) ............................................................................ 59
`Smith & Nephew, Inc. v. ConforMIS, Inc.,
`IPR2017-00511, 2018 WL 2972960, (P.T.A.B. June 11, 2018) ........................ 34
`
`- iv -
`
`
`
`
`
`Solvay S.A. v. Honeywell Int’l Inc.,
`742 F.3d 998 (Fed. Cir. 2014) ............................................................................ 54
`Taskett v. Dentlinger,
`344 F.3d 1337 (Fed. Cir. 2003) .................................................................... 55, 59
`Trintec Indus., Inc. v. Top-U.S.A. Corp.,
`295 F.3d 1292 (Fed. Cir. 2002) .......................................................................... 45
`Williams v. Adm’r of NASA,
`463 F.2d 1391 (C.C.P.A. 1972) ................................................................... 54, 59
`Xilinx, Inc. v. Intellectual Ventures I LLC,
`IPR2013-00112, 2014 WL 2965700 (P.T.A.B. June 26, 2014) ......................... 33
`Statutes
`35 U.S.C. § 102(e) ............................................................................................ passim
`35 U.S.C. § 102(g) ........................................................................................... passim
`35 U.S.C. § 103 ......................................................................................................... 1
`Other Authorities
`37 C.F.R. § 42.104(b)(3) ......................................................................................... 40
`37 C.F.R. § 42.120 .................................................................................................... 1
`U.S. Patent No. 5,859,601 ................................................................................ passim
`
`- v -
`
`
`
`
`
`EXHIBIT LISTING
`
`EXHIBIT NO.
`
`DESCRIPTION
`
`2001
`
`2002
`
`2003
`
`2004
`
`2005
`
`2006
`
`2007
`
`2008
`
`2009
`
`2010
`
`University of Minnesota Charter (filed May 24, 2017)
`
`University of Minnesota Consolidated Financial Statements
`for the Years Ended June 30, 2016 and 2015 (filed May 24,
`2017)
`
`Transcript of January 3, 2018 Conference Call (filed June 5,
`2018)
`
`Statutory Disclaimer filed by Patent Owner (filed February
`18, 2020)
`
`Declaration of Christopher Verdini in Support of Motion for
`Pro Hac Vice Admission (filed May 13, 2020)
`
`Declaration of Anna Shabalov in Support of Motion for Pro
`Hac Vice Admission (filed May 13, 2020)
`
`Declaration of Professor Emina Soljanin in Regents of the
`University of Minnesota v. LSI Corporation et al., Case No.
`18-cv-00821-EJD-NMC, Dkt. 204-4 (N.D. Cal. Apr. 13,
`2018)
`
`Transcript of May 9, 2018 Deposition of Prof. Emina
`Soljanin in Regents of the University of Minnesota v. LSI
`Corporation et al., Case No. 18-cv-00821-EJD-NMC (N.D.
`Cal.)
`
`B. Marcus and E. Soljanin, “Modulation Codes for Storage
`Systems,” Chapter 11 of Coding and Signal Processing for
`Magnetic Recording Channels, B. Vasic and E. Kurtas, eds.,
`CRC Press, 2005
`
`E. Soljanin, “Coding for Improving Noise Immunity in
`Multi-Track Multi-Head Recording Systems,” Ph.D. thesis,
`Texas A&M Univ., 1994
`
`- vi -
`
`
`
`
`
`EXHIBIT NO.
`
`DESCRIPTION
`
`2011
`
`2012
`
`2013
`
`2014
`
`2015
`
`2016
`
`2017
`
`2018
`
`2019
`
`2020
`
`2021
`
`2022
`
`2023
`
`Transcript of June 5, 2020 Deposition of Prof. Emina
`Soljanin
`
`NSIC/DARPA Ultra-High-Density Recording Project
`Agreement, March 19, 1993
`
`November 1, 1995 Letter from Robert Kost of Seagate
`Technology to Nathan Malek of the University of Minnesota
`
`Letter from Sharon Rotter of NSIC to Nathan Malek of the
`University of Minnesota
`
`December 27, 1995 facsimile from Nathan Malek of the
`University of Minnesota to Sharon Rotter of NSIC
`
`Declaration of Prof. Jaekyun Moon
`
`Declaration of Prof. Steven W. McLaughlin
`
`H. Shafiee, B. Rub and R. Kost, “Signal Space Detectors for
`MTR-Coded Magnetic Recording Channels,” IEEE Trans.
`on Magnetics, vol. 34, no. 1, January 1998, pp. 141–46
`
`J. Moon and L. R. Carley, “Performance Comparison of
`Detection Methods in Magnetic Recording,” IEEE Trans. on
`Magnetics, vol. 26, no. 6, November 1990, pp. 3155–72
`
`Table of Contents, Intermag 1996, April 9–12, 1996, Seattle,
`WA
`
`U.S. Provisional Patent Serial No. 60/014,954, filed April 5,
`1996
`
`Obituary of Kin Hing Paul Tsang, Star Tribune, March 26,
`2014
`
`M. Fischetti, “Going Vertical,” Scientific American, August
`2006, pp. 90–91
`
`- vii -
`
`
`
`
`
`EXHIBIT NO.
`
`DESCRIPTION
`
`2024
`
`2025
`
`2026
`
`2027
`
`2028
`
`2029
`
`2030
`
`2031
`
`2032
`
`2033
`
`2034
`
`Excerpts from S. Wang and A. Taratorin, Magnetic
`Information Storage Technology, Academic Press, 1999
`
`B. Brickner and J. Moon, “Seagate Annual Report,”
`University of Minnesota, Center for Micromagnetics and
`Information Technologies, September 26, 1995
`
`P. Siegal, “Recording Codes for Digital Magnetic Storage,”
`IEEE Trans. on Magnetics, vol. Mag.-21, no. 5, Sept. 1985,
`pp. 1344–49
`
`Excerpts from K. Ashar, Magnetic Disk Drive Technology,
`IEEE Press, 1997
`
`Excerpts from H. N. Bertram, Theory of Magnetic
`Recording, Cambridge University Press, 1994
`
`Excerpts from Merriam-Webster’s Collegiate Dictionary,
`10th Ed., 1996
`
`Image of Plaque Awarded to Professor Moon by NSIC for
`“Technical Achievement Award, 1997” for “creation and
`development of the Maximum Transition Run Code”
`
`Excerpts from The American Heritage Dictionary, 2nd
`College Ed., 1985
`
`University of Minnesota Office of Research Administration
`Notice of Grant or Contract Award to Seagate Tech. Corp.,
`dated March 18, 1997
`
`B. Brickner and J. Moon, “Coding for Increased Distance
`With a d=0 FDTS/DF Detector,” University of Minnesota,
`Center for Micromagnetics and Information Technologies,
`May 25, 1995
`
`Seagate Technology Twin Cities Operations Technology
`Monthly Progress Report, July 12, 1995
`
`- viii -
`
`
`
`
`
`
`
`EXHIBIT NO.
`
`DESCRIPTION
`
`2035
`
`2036
`
`2037
`
`University of Minnesota Invention Disclosure Form, Sept. 8,
`1995
`
`B. Vasic, P. Aziz and N. Sayiner, “Read Channels for Hard
`Drives,” Chapter 15 of Coding and Signal Processing for
`Magnetic Recording Channels, B. Vasic and E. Kurtas, eds.,
`CRC Press, 2005
`
`Declaration of Mark G. Knedeisen
`
`
`
`
`- ix -
`
`
`
`
`
`CHALLENGED CLAIMS
`
`13. A method for encoding m-bit binary datawords into n-bit binary codewords in
`
`a recorded waveform, where m and n are preselected positive integers such that n
`
`is greater than m, comprising the steps of:
`
`receiving binary datawords; and
`
`producing sequences of n-bit codewords;
`
`imposing a pair of constraints (j;k) on the encoded waveform;
`
`generating no more than j consecutive transitions of said sequence in the
`
`recorded waveform such that j≥2; and
`
`generating no more than k consecutive sample periods of said sequences
`
`without a transition in the recorded waveform.
`
`
`
`14. The method as in claim 13 wherein the consecutive transition limit is defined
`
`by the equation 2≤j<10.
`
`
`
`17. The method as in claim 14 wherein the binary sequences produced by
`
`combining codewords have no more than one of j consecutive transitions from 0 to
`
`1 and from 1 to 0 and no more than one of k+1 consecutive 0’s and k+1
`
`consecutive 1’s when used in conjunction with the NRZ recording format.
`
`- x -
`
`
`
`
`
`I.
`
`INTRODUCTION
`The Board granted institution for claims 13, 14, and 17 (“Challenged
`
`Claims”) of U.S. Patent No. 5,859,601 (“’601 Patent,” Ex. 1001) on two very
`
`narrow grounds, i.e., that the Challenged Claims are anticipated by Okada (Ex.
`
`1007) and by the Tsang Patent (Ex. 1009). Petitioners did not challenge those
`
`claims as being invalid for obviousness under 35 U.S.C. § 103. Patent Owner,
`
`Regents of the University of Minnesota (“UMN”), submits this Patent Owner
`
`Response (“POR”) under 37 C.F.R. § 42.120.
`
`The ’601 Patent addresses a problem in magnetic recording wherein a
`
`recorded waveform containing a large number of consecutive “transitions” is more
`
`prone to errors in the detection process, Ex. 1001, col. 3:53–57, where a
`
`“transition” is a reversal in the magnetic orientation of adjacent bit regions along a
`
`recording track of a magnetic recording medium. To address the problem,
`
`Professor Jaekyn Moon and his then-Ph.D. student at UMN, Barrett Brickner,
`
`invented a novel encoding scheme for magnetic recording referred to as
`
`“Maximum Transition Run” (“MTR”) codes. Id., Abstract. The inventive MTR
`
`codes of the Challenged Claims prevent “more than j consecutive transitions” from
`
`being written to a magnetic recording medium and limit the number of consecutive
`
`nontransitions “to no more than k.” Id., col. 2:59-61; col. 4:48.
`
`- 1 -
`
`
`
`
`
`Neither Okada nor the Tsang Patent anticipate the Challenged Claims.
`
`Okada describes an optical data storage system that not does limit consecutive
`
`“transitions” of any kind in the recording medium, much less magnetic transitions,
`
`as described in the ’601 Patent and required by the Challenged Claims. Instead,
`
`Okada prevents an optical head from being pulsed “on” too many (three) times in a
`
`row, which is not a limit on consecutive “transitions” under any reasonable
`
`interpretation of the term. Okada also fails to impose a k constraint on successive
`
`nontransitions because its coding rules do not constrain the number of successive
`
`times the optical head can be “off.”
`
`To supplement their argument that Okada anticipates the Challenged Claims,
`
`Petitioners rely exclusively on the testimony of their expert, Professor Emina
`
`Soljanin (“Soljanin”), but her testimony is unreliable and inconsistent in multiple
`
`respects. Among other things, she rendered herself incapable of opining on
`
`anticipation of the Challenged Claims by asserting, in sworn testimony in
`
`connection with the related district court proceeding,1 that five terms in the
`
`Challenged Claims were indefinite. Ex. 2007, ¶¶ 37–59. If the claims allegedly
`
`
`1 Regents of the Univ. of Minn. v. LSI Corp. et al., No. 5:18-cv-00821-EJD (N.D.
`
`Cal.) (the “Litigation”). The Litigation was stayed pending this IPR before any
`
`rulings on claim construction or validity. See Dkt. 211 (May 11, 2018).
`
`- 2 -
`
`
`
`
`
`“fail to inform, with reasonable certainty, those skilled in the art about the scope of
`
`the invention” (Ex. 2007, ¶ 35), Soljanin can hardly now find those elements of the
`
`Challenged Claims in any prior art reference. See Enzo Biochem, Inc. v. Applera
`
`Corp., 599 F.3d 1325, 1332 (Fed. Cir. 2010) (first step in anticipation analysis
`
`requires construing the claim; if a claim is indefinite, by definition, it cannot be
`
`construed); Honeywell Int’l, Inc. v. Int’l Trade Comm’n, 341 F.3d 1332, 1342 (Fed.
`
`Cir. 2003) (without a discernable claim construction, an anticipation analysis
`
`cannot be performed).
`
`Soljanin also admitted that she is “not familiar with optical recording
`
`physics”—the very subject of Okada—and does not “know how 1’s and 0’s are
`
`physically recorded in general” in Okada’s optical storage system. Ex. 2011, pp.
`
`72–76. Additionally, Soljanin contradicted herself on whether Okada discloses the
`
`required j constraint of the Challenged Claims. In her declaration, Soljanin
`
`asserted that the j constraint in Okada is two (Ex. 1010, ¶¶ 99, 100, 102, 110, 112–
`
`13). On cross-examination, however, Soljanin testified that the j constraint in
`
`Okada was four or eight, and then later admitted it could be twelve. Ex. 2011, pp.
`
`92–93. In light of these and other critical deficiencies, the Board should not give
`
`any weight to Soljanin’s testimony.
`
`The Tsang Patent does not anticipate the Challenged Claims because it does
`
`not qualify as prior art under either 35 U.S.C. § 102(e) or § 102(g), as alleged by
`
`- 3 -
`
`
`
`
`
`Petitioners.2 Moon and Brickner invented MTR codes prior to the filing date of the
`
`Tsang Patent. Petitioners, in fact, unwittingly admit that Moon and Brickner
`
`conceived MTR codes first by citing an allegedly even earlier disclosure of MTR
`
`codes referred to in the Tsang Patent as the “Seagate Annual Report.” Petition at
`
`6. But, Moon and Brickner—not Tsang—authored the Seagate Annual Report
`
`(Ex. 2025) prior to the filing date of the Tsang Patent. Tsang was working for
`
`Seagate at the time Moon and Brickner wrote the Seagate Annual Report (summer
`
`of 1995) and Tsang received the Seagate Annual Report from Moon and Brickner
`
`before he filed his patent application.3 Thus, the Tsang Patent’s filing date does
`
`not pre-date Moon/Bricker’s invention date. Nor is the Tsang Patent an invention
`
`“by another” as required by §§ 102(e) and (g).
`
`
`2 Tsang’s alleged prior invention under § 102(g) cannot be used to cancel a claim
`
`in an inter partes review because an IPR must be based on prior art consisting of
`
`patents or printed publications. See Becton, Dickinson and Co. v. Baxter Corp.
`
`Englewood, IPR2019-00119, Paper 15 at 17 (May 3, 2019) (citing 35 U.S.C.
`
`§ 311(a)).
`
`3 To avoid confusion, Ex. 1009 is referred to as the “Tsang Patent” and the inventor
`
`thereof is referred to as “Tsang.”
`
`- 4 -
`
`
`
`
`
`In support of this POR, UMN provides declarations from Professor Steven
`
`W. McLaughlin (Ex. 2017) and Professor Moon (Ex. 2016). Prof. McLaughlin is
`
`the Dean of the College of Engineering at the Georgia Institute of Technology and
`
`is an expert on coding technologies, including for both magnetic and optical
`
`recording. Ex. 2017, Section I. His renown in this field led Judge Posner to
`
`appoint him as the court’s independent technical advisor in Apple, Inc. v.
`
`Motorola, Inc., No. 1-11–cv- 8540 (N.D. Ill.) (Dkt. 677 at 35). His declaration
`
`explains, among other things, that Okada does not disclose all elements of the
`
`Challenged Claims.
`
`Prof. Moon is the first named inventor of the ’601 Patent. His declaration
`
`describes and documents the events surrounding Moon/Brickner’s invention of
`
`MTR codes in 1995, including conception and reduction to practice, and the
`
`disclosure of their invention to Seagate, including to Tsang, who worked for
`
`Seagate at the time.
`
`II.
`
`SUMMARY OF THE ’601 PATENT
`The ’601 Patent relates to magnetic data storage systems, such as hard disk
`
`drives (“HDD”) and magnetic tape systems. Ex. 1001, col. 1:9–10; col. 2:40–43;
`
`col. 2:59–61. UMN provides the following summary of how MTR codes operate
`
`in HDDs. Additional details are provided in Exs. 2016 and 2017.
`
`- 5 -
`
`
`
`
`
`A. HDD Basics
`A HDD includes a magnetically-coated disk that stores data in concentric
`
`recording tracks. A “read/write” head writes data to, and reads data from, the disk.
`
`It writes data by magnetizing microscopic bit regions along a recording track on
`
`the disk. Later, when the previously-written data are read, the read head generates
`
`a “readback signal” from the magnetic fields emanating from the bit regions along
`
`the track. The readback signal has fluctuations due to the reversals in the magnetic
`
`fields from the bit region transitions and a “read channel” in the HDD, using signal
`
`processing techniques, detects the written data from the readback signal. Ex. 2017,
`
`¶ 7; Ex. 2016, ¶ 17.
`
`In most modern HDDs, the data are modified in at least two ways prior to
`
`writing the data to the disk. First, the user data are encoded according to
`
`
`
`- 6 -
`
`
`
`
`
`applicable modulation codes, such as and including MTR codes. The modulation
`
`codes, including MTR codes, map data bits into an encoded sequence of symbols
`
`that prevent certain characteristics in the stream of symbols that make their
`
`recovery difficult. Ex. 1001, col. 1:15–21. Second, a processor converts the
`
`encoded sequence into an analog waveform that the write head records on the disk
`
`by magnetically polarizing the regions on the disk in accordance with the
`
`waveform. Ex. 2017, ¶ 13; Ex. 2016, ¶ 19.
`
`Each polarized region on the disk has a magnetic polarization that, once
`
`written, is oriented in a particular direction. To write data to the disk, the write
`
`head can reverse the magnetic polarity of these regions from one direction to its
`
`opposite by varying the polarity of the magnetic field emitted by the write head. In
`
`so-called “longitudinal magnetic recording,” which was prevalent at the time of the
`
`invention of the ’601 Patent, the bit regions are polarized in the same plane as the
`
`magnetic layer, as illustrated in the diagram below. Ex. 2017, ¶ 8; Ex 2016, ¶ 20.
`
`
`
`- 7 -
`
`
`
`
`
`The polarized regions can be conceptualized as bar magnets having north
`
`(N) and south (S) poles. There are four possibilities for two adjacent polarized
`
`regions―two where the magnetic orientation switches direction and two where it
`
`does not―as shown below. Ex. 2017, ¶ 9.
`
`No Reversal in Magnetic Orientation
`Between Adjacent Bit Regions
`
`A Reversal in Magnetic Orientation
`Between Adjacent Bit Regions
`
`
`
`
`
`
`
`
`
`The reversals in magnetic orientation between adjacent bit regions on the
`
`
`
`physical disk are called “transitions.” Ex. 2017, ¶ 10; Ex. 2016, ¶ 21; Ex. 2011 at
`
`p. 56 (Soljanin testifying that a “transition” in the magnetic recording context is
`
`“from one polarization to another” and “from one magnetization to another, could
`
`be from one magnetization direction to another”). Due to micro-magnetic effects,
`
`transitions generate more noise than nontransitions, and that noise complicates
`
`reading the data. As data density increases over time through device
`
`miniaturization, the density of the transitions increases, which increases the
`
`transition-related noise. Presently, noise from transitions is the dominant noise
`
`source in HDDs. Ex. 2017, ¶¶ 25–26; Ex. 2016, ¶ 32.
`
`HDDs typically use a Non-Return-to-Zero Inverted (“NRZI”) system to
`
`write data. With NRZI, if the data bit to be written to the disk is a binary “1,” the
`
`- 8 -
`
`
`
`
`
`direction of the current in the write head reverses, thereby reversing the
`
`magnetization of the corresponding bit region on the disk being written. The
`
`reversed magnetization creates a magnetic transition relative to the immediately
`
`prior bit region. Conversely, if the data bit to be written to the disk is a binary “0,”
`
`the write head does not reverse the magnetization of the bit region relative to the
`
`prior region. Ex. 1001, col. 1:30–34; Ex. 2017, ¶ 12; Ex. 2016, ¶ 22.4
`
`B. Reading Data From a Disk
`To read the written data, the read head, flying above the rotating disk,
`
`detects the variations in the magnetic flux from the magnetized bit regions and
`
`converts the sensed magnetic fields into a continuous, analog electrical signal
`
`called the “readback signal.” A detector in the read channel detects the sequence
`
`of transitions and nontransitions that are on the disk from the readback signal to
`
`recover the written sequence. Ex. 2017, ¶ 14; Ex. 2016, ¶ 25.
`
`Early HDD read channels used “peak” or “threshold” detectors. If the
`
`readback signal value, after rectification (i.e., converting from alternating current
`
`
`4 The ’601 Patent describes another recording format, Non-Return-to-Zero
`
`(“NRZ”), where a binary “1” represents a positive level in the magnetization
`
`waveform and the binary “0” represents a negative level of the waveform. Ex.
`
`1001, col. 1:24–27; Ex. 2017, ¶ 12; Ex. 2016, ¶ 23.
`
`- 9 -
`
`
`
`
`
`to direct current), was above a threshold, the peak detector detected a transition.
`
`At low data densities, peak detectors were adequate because intersymbol
`
`interference (“ISI”) effects between the bit regions were small. Ex. 2017, ¶ 15.
`
`In the 1990s, the HDD industry migrated to more sophisticated “partial
`
`response maximum likelihood” (“PRML”) detectors to accommodate the increased
`
`ISI effects that occur with higher data densities. Ex. 2017, ¶ 16. Unlike peak
`
`detectors that use the analog readback signal, PRML detectors are digital sequence
`
`detectors that use digitized samples of the readback signal. PRML detectors also
`
`incorporate some form of a “maximum likelihood sequence detector,” such as a
`
`Viterbi detector, that accounts for the ISI in the readback signal to estimate the
`
`most likely sequence of data written to the disk. Ex. 2017, ¶ 16; Ex. 2016, ¶ 26.
`
`Using a trellis-based search, a Viterbi detector considers various possible bit
`
`sequences and efficiently compares the expected values for the possible bit
`
`sequence with the readback signal sample values to determine the most likely
`
`sequence written to the disk. Ex. 2017, ¶¶ 17–18; Ex. 2016, ¶ 29; see also
`
`Carnegie Mellon Univ. v. Marvell Tech. Grp., Ltd., 801 F.3d 1283, 1290 (Fed. Cir.
`
`2015) (explaining Viterbi detection).
`
`Below is an example of a trellis having 8 nodes at each (vertical) sampling
`
`time instance (the times when the readback signal is sampled). The 8 nodes
`
`correspond to the 8 possible 3-bit sequences (e.g., 000, 001, …, 111). In this
`
`- 10 -
`
`
`
`
`
`example, NRZI recording is assumed (a nontransition on the disk labeled with a 0
`
`and a transition on the disk labeled with a 1). Thus, the upper-left node (000)
`
`represents a sequence of nontransition-nontransition-nontransition.
`
`
`There are two “branches” leaving each node because the next bit must be
`
`either a 0 or a 1, i.e., the next bit region either has the same magnetization (a
`
`nontransition) or an opposite magnetization (a transition) relative to the prior bit
`
`region. The upper-left node illustrates this principle as there is (i) a first branch
`
`going to the node 000 in the next time instance of the trellis, indicating that the
`
`- 11 -
`
`
`
`
`
`next region is a nontransition and (ii) a second branch going to the node 001,
`
`indicating that the next region is a transition. Ex. 2017, ¶ 18.
`
`There is a one-to-one correspondence between a stored NRZI sequence and
`
`a “path” through the trellis. A path consists of a series of branches end-to-end
`
`through the trellis that corresponds to a NRZI sequence of transitions and
`
`nontransitions written to the disk. The red path above starts at the 001 node,
`
`meaning that the first three bits in the red path are 0-0-1. The next node is 010,
`
`indicating that the next (4th) bit is a 0 (i.e., the last bit represented by the 010
`
`node). The next node is 101, indicating that the next (5th) bit is a 1 (i.e., the last
`
`bit represented by the 101 node). The final node is 010, indicating the final (6th)
`
`bit is a 0 (i.e., the last bit represented by the 010 node). Thus, the red path above
`
`represents the 6-bit sequence 0-0-1-0-1-0, as shown below. Ex. 2017, ¶¶ 20–21.
`
`
`
`- 12 -
`
`
`
`
`
`To detect the sequence of transition/nontransitions written to the disk, the
`
`Viterbi detector computes “branch metric values” for the branches of numerous
`
`paths through the trellis, and sums the branch metric values along the paths to
`
`compute “path metric values.” The branch metric value for a branch is the
`
`measure of the distance (or error) between the signal sample value(s) of the
`
`readback signal and the expected (or “target”) channel output value(s) for the
`
`branch. The target values (which could be, for example, -1, 0, and +1) depend on
`
`whether the branch represents a negative transition, a nontransition, or a positive
`
`transition, respectively. Ex. 2017, ¶ 22; Ex. 2016, ¶ 30. The “path metric value”
`
`for a given path is the sum of the branch metric values for the branches along the
`
`path, so a path metric value can be thought of as the cumulative distance (that is,
`
`error) between the error-free target and the readback signal for the sequence of
`
`branches along a particular path. The sequence corresponding to the path with the
`
`best (lowest) path metric value is the path the detector determines is the most likely
`
`sequence of transitions/nontransitions written to the disk. Ex. 2017, ¶ 23.
`
`C.
`Problem Addressed by the ’601 Patent
`One problem experienced with sequence detectors is that there are write
`
`patterns (i.e., recorded NRZI sequences) whose corresponding path metrics are
`
`“close” in distance to other paths (so-called “error patterns”). Consequently, even
`
`small amounts of noise can affect the computed path metric values such that the
`
`- 13 -
`
`
`
`
`
`detector selects an incorrect, but numerically close, path (i.e., having the lower
`
`path metric value) to be the path corresponding to written sequence. When the
`
`detector selects error patterns associated with these “close” trellis paths and
`
`sequences with unacceptably high frequency, the error rate of a sequence detector
`
`is too high (e.g., above a desired level) and, thus, unusable in an HDD. Ex. 1001,
`
`col. 18–26; Ex. 2017, ¶ 27; Ex. 2016, ¶ 34. These errors occur more frequently as
`
`data density increases, because of the corresponding increase in the density of the
`
`transitions on the disk, which are the dominant noise source in HDDs. Ex. 2017.
`
`¶¶ 25–26; Ex. 2016, ¶ 32.
`
`Figure 1 of ’601 Patent shows four exemplary write pattern pairs that tend to
`
`cause sequence detection errors. At least one write pattern of each pair, when
`
`written to the disk, has more than two consecutive transitions and the middle three
`
`pulses are opposite for each pair. Ex. 2017, ¶ 28; Ex. 2016, ¶ 36.
`
`- 14 -
`
`
`
`
`
`
`
`Pairs of Written Patterns from Figure 1
`of the ’601 Patent
`
`
`
`Middle 3 pulses high-low-high
`
`Middle 3 pulses low-high-low
`
`Middle 3 pulses low-high-low
`
`Middle 3 pulses high-low-high
`
`Middle 3 pulses high-low-high
`
`Middle 3 pulses low-high-low
`
`Middle 3 pulses low-high-low
`
`Middle 3 pulses high-low-high
`
`
`
`
`
`
`
`
`
`As an example, the upper pattern in Pair 1 above represents a sequence of
`
`transition-transition-transition-nontransition (or T-T-T-NT) because, as shown
`
`below, the signal goes from low to high, then high to low, then low to high, then
`
`stays high.
`
`T
`
`T
`
`T
`
`NT
`
`
`
`- 15 -
`
`
`
`
Accessing this document will incur an additional charge of $.
After purchase, you can access this document again without charge.
Accept $ Charge
Still Working On It
This document is taking longer than usual to download. This can happen if we need to contact the court directly to obtain the document and their servers are running slowly.
Give it another minute or two to complete, and then try the refresh button.
A few More Minutes ... Still Working
It can take up to 5 minutes for us to download a document if the court servers are running slowly.
Thank you for your continued patience.
This document could not be displayed.
We could not find this document within its docket. Please go back to the docket page and check the link. If that does not work, go back to the docket and refresh it to pull the newest information.
Your account does not support viewing this document.
You need a Paid Account to view this document. Click here to change your account type.
Your account does not support viewing this document.
Set your membership
status to view this document.
With a Docket Alarm membership, you'll
get a whole lot more, including:
- Up-to-date information for this case.
- Email alerts whenever there is an update.
- Full text search for other cases.
- Get email alerts whenever a new case matches your search.
One Moment Please
The filing “” is large (MB) and is being downloaded.
Please refresh this page in a few minutes to see if the filing has been downloaded. The filing will also be emailed to you when the download completes.
Your document is on its way!
If you do not receive the document in five minutes, contact support at support@docketalarm.com.
Sealed Document
We are unable to display this document, it may be under a court ordered seal.
If you have proper credentials to access the file, you may proceed directly to the court's system using your government issued username and password.
Access Government Site
