US 5592332

I'll search for the specific patent number 5592332 across sources.

I have the bibliographic data and considerable claim text. Let me pin down the abstract, the full independent-claim set, and any 2026 CAFC/litigation activity.

Let me retrieve the abstract text and confirm the independent-claim structure.

US Patent 5,592,332 — Analyst Summary

Note on scope: I ran live searches for the exact number 5,592,332. I found the patent's own records (Google Patents, Justia, EveryPatent) and numerous citing/opposing documents. I found no 2026 CAFC docket, IPR, or district-court case referencing 5,592,332 (see "Litigation" below).

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1. Bibliographic data

Identifier note (per your strict rule): I am reporting the title literally as "Renticular lens…" — that is the spelling used by Google Patents and by several citing patents (e.g., US6282034, US20070223232, US7804649). The specification body itself consistently says "lenticular lens," so "Renticular" appears to be a typographical/OCR variant in the title field. I am not correcting it.

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2. Abstract

⚠️ Uncertainty flag: I was not able to retrieve the verbatim abstract text from the sources reached in this session (the Google Patents fetch I obtained rendered the description, figures list, classifications and "Definitions," but not the abstract block). What the record supports is the following substance of the disclosure, drawn from the specification's own summary and claim language:

The invention concerns a lenticular lens having a light‑transmitting substrate bearing many parallel, ridge‑aligned lens elements (triangular‑prism, or concave/convex curved elements); a surface light source (back‑light type and edge‑light type) using that lenticular lens, optionally with a light‑isotropic (delustered‑transparent) diffusing layer; and a liquid crystal display apparatus using the surface light source as a backlight. The lens elements are defined so that the transmitted‑light intensity distribution satisfies 30° ≤ θ₁₀% ≤ 100° and R ≤ 20%, where θ₁₀% is the angular range within which intensity is ≥10% of the main‑lobe peak, and R is the side‑lobe‑to‑main‑lobe ratio. This suppresses side lobes (light loss/stray light) while preserving equal, isotropic diffusion — avoiding higher power consumption and heat generation.

I would not treat the paragraph above as a verbatim abstract; it is a faithful paraphrase of the disclosed summary.

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3. Independent claims — plain-language overview

Claim-count caveat: My retrieved sources show claim text running at least to claim 62 (claims 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 46, 54, 55, 61, 62 all appear as independent-style "A … comprising:" claims). The Google Patents page did not state a total claim count (the "17" shown next to "liquid crystal" in its term-frequency table is an occurrence count, not a claim count). Treat the enumeration below as the independent claims I could verify, not necessarily an exhaustive list.

A. The "lenticular lens" families (first invention)

• Claim 1 (and the parallel convex version, claim 35): A lenticular lens = light‑transmitting substrate with two opposed surfaces + a plurality of parallel, ridge‑aligned elongated lens elements of concave or convex cross‑section on one surface, characterized by 30° ≤ θ₁₀% ≤ 100° and R ≤ 20%. This is the core, broadest claim.
• Claims 36–38: Surface light sources (rectangular‑parallelpiped‑cavity light guide; linear source at a side edge; light‑isotropic diffusing layer on the front surface) combined with a lenticular lens. Beyond the θ₁₀%/R limits, they add triangular‑prism elements with vertical angle 95°–110° (cl. 36) or concave elements whose main cross‑section follows a quadratic curve / Rankine‑egg shape / linear‑function curve (cl. 37–38).

B. The "elliptic‑cylinder lens sheet / surface light source" families (third invention)

• Claim 30 (and 41, 42, 43): A surface light source = light guide (plate or rectangular cavity) + linear or point source at a side edge + reflecting layer on the rear + a concave lenticular lens having elliptic cylinder lens elements, the longer axis aligned with the normal of the emitting surface, satisfying:
  • 1.40 ≤ n ≤ 1.6; 1.20 ≤ (longer axis/shorter axis) ≤ 2.00; 0.1 ≤ (cutting depth/longer axis) ≤ 0.50.
• Claims 39 (and 40): A lens sheet with a mat surface ≤100 µm on the non‑lens side of a concave lenticular lens, where the elliptic elements satisfy 1.1·n/(n²−1)^½ ≥ (longer/shorter axis) ≥ 0.9·n/(n²−1)^½ (cl. 39) — the aberration‑free ellipse condition — or, for hyperbolic elements, the asymptote slope lies within ±10% of n/(n²−1)^½ (cl. 40).
• Claim 33 (display apparatus): The claim‑30‑type surface light source plus a transmission‑type display device layered over the light‑emitting surface — i.e., the LCD panel combination.
• Claim 34 (and 61, 62): A lamp‑house configuration: linear (or point) source whose lower/side surfaces are enclosed by a lamp house with an opening and inner reflecting surface, with the specified lenticular lens covering the opening, meeting the θ₁₀%/R and elliptic‑parameter limits.
• Claim 46: A surface light source (rectangular‑cavity guide, linear source, reflecting layer) with a convex lenticular lens. Caution: the text I retrieved describes it as "a convex lenticular lens … having concave shaped cross sections," which is internally inconsistent — likely truncation/OCR loss in the source. I flag this rather than resolve it.
• Claim 54 / 55: Surface light sources reciting hyperbolic cylinder lens elements (cl. 54) and the refractive‑index / axis‑ratio / cutting‑depth parameter set (cl. 55), the lens sheet being layered on the light‑emitting surface.
• Claims 56–60: Further independent surface‑light‑source claims; the retrieved excerpts are truncated before the characterizing language, so I cannot reliably state their scope. Uncertain.

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4. Litigation / CAFC 2026 dockets — no hits

• No CAFC 2026 docket, PTAB proceeding, or district‑court action referencing 5,592,332 was found in the searches performed. Given the patent's expiration on Jan 7, 2014, a live 2026 Federal Circuit appeal on this patent is highly improbable.
• What does exist is heavy citation traffic: 5,592,332 is cited as prior art in later backlight/lenticular patents (e.g., US8,142,041; US7,295,262; US7,474,464; EP1972972A2; EP1767962A4; WO2001004681; EP2293140A1), and is described in EPO/PCT search reports as anticipatory ("X") or material ("IY") art against several later applications.
• ⚠️ Methodological caveat: I searched public web indexes (Google Patents, Justia, EveryPatent, Docket Alarm-hosted documents, EPO data). I did not have direct PACER/CAFC docket-system access in this session, so I cannot assert a negative with absolute certainty — only that no 2026 CAFC activity surfaced.

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5. Sources used

• Google Patents: https://patents.google.com/patent/[US5592332](/patent/US5592332)/en (bibliographic data, description, classifications, legal status)
• Justia Patents: https://patents.justia.com/patent/5592332 (Patent History, examiners, cited art, claims 46–62 excerpts)
• EveryPatent: http://www.everypatent.com/comp/pat5592332.html (claims 30–43 excerpts, measured‑transmittance examples)
• EPO/PCT search reports citing US 5,592,332 (WO2001004681A1; WO02/48791A1 family/claims tables) — confirming the JP/KR family members and the "X" prior‑art treatment
• Citing patents listing US 5,592,332 (US8,142,041; US7,295,262; US7,474,464; US6,282,034; US7,804,649; US2007/0223232)

6. Bottom line

US 5,592,332 is a Dai Nippon Printing patent (Nishio et al.) on side‑lobe‑suppressed lenticular lenses and their use in edge‑light/back‑light surface light sources and LCD backlights, defined numerically by θ₁₀% (30°–100°) and side‑lobe/main‑lobe ratio R ≤ 20%, with later claims adding the spherical‑aberration‑free elliptic‑cylinder geometry (1.20–2.00 axis ratio; 0.10–0.50 cutting‑depth ratio) and a mat‑surface‑cavity light guide interface. It is expired, and no 2026 CAFC activity on it was found. The two items I could not verify authoritatively are (a) the verbatim abstract text and (b) the complete, renumbered list of all independent claims.

I'll search for litigation records involving US patent 5,592,332.

Let me search more specific litigation databases.

Summary of Findings — Litigation Involving U.S. Patent No. 5,592,332

Important caveat up front: I was unable to locate any litigation record that specifically and unambiguously names U.S. Patent No. 5,592,332 (the Dai Nippon Printing lenticular lens / surface light source patent) as an asserted patent. The searches returned no district court complaints, dockets, PTAB proceedings, or CAFC appeals that expressly identify the '332 patent. I flag this explicitly rather than fabricate case details, per the operating rules.

What the searches did and did not show

1. Patent-office / prior-art citations (not litigation). The '332 patent appears repeatedly as a cited reference in prosecution and search reports — e.g., the PCT/EP 00/05935 International Search Report (WO2001004681A1) cites "US 5 592 332 A (NISHIO TOSHIKAZU ET AL)" as an X-category reference, and EP2293140A1 lists it in the description. These are citation events, not litigation.

2. No PTAB record found. Nothing in the search results shows an IPR, PGR, or reexam involving the '332 patent.

3. Dai Nippon Printing (the assignee of '332) did appear in litigation around the relevant era, but I could not confirm the '332 patent was asserted in any of them. Potentially relevant cases found:

These cases involve optical-sheet/display technology consistent with DNP's lenticular-lens business, and the '332 patent's technology (lenticular lens sheets for LCD backlights) is plausibly the subject matter — but the docket summaries I retrieved do not state which patents were asserted. I cannot confirm '332 was among them.

1. Unrelated numeric matches (not the patent). Results such as a Czech insolvency claim (account "5592332/0800"), a Brazilian corporate registration ("5592332 JOSE ELSON MARTINS DA"), and a Japanese document's "US 5592333 A" are coincidental number matches and are not litigation involving this patent.

Bottom line

• Known litigation expressly involving U.S. Pat. No. 5,592,332: none identified.
• The patent is Expired – Lifetime (anticipated expiration Jan. 7, 2014; 20-year term from the 1993-12-27 filing), which materially reduces the likelihood of any recent assertion and is consistent with a sparse litigation history.
• The DNP-related cases listed above are the closest candidates, but confirming whether the '332 patent was asserted would require pulling the actual complaints/E-Discovery documents from PACER (D.N.J. 2:08-cv-05515; E.D. Tex. 5:09-cv-00135; D. Nev. 2:09-cv-01635), which I could not access in these searches.

Recommendation for definitive verification: Retrieve the complaint PDFs for the three dockets above from PACER / CourtListener / the Unified Patents litigation portal (https://portal.unifiedpatents.com/litigation/caselist) and check the "patents-in-suit" field for 5,592,332. If you would like, I can attempt targeted searches against those specific dockets.

I'll verify the structured data against public sources before writing anything.

Proceedings overview

Zero AIA trial proceedings are on file for US 5,592,332 — no IPR, no PGR, no CBM. The structured ODP block states no AIA trial proceedings exist, and my independent web checks surfaced no petition, institution decision, Final Written Decision, or Federal Circuit appeal naming this patent. Because nothing was ever instituted, the patent is neither "hardened" by surviving IPRs nor narrowed by cancellation: every claim is untested, and no § 315(e)(2) estoppel attaches to anyone. The bottom line for a defendant is not about PTAB outcomes at all — the patent's term expired 2014-01-07, so any demand letter citing it is, practically speaking, uncollectible.

Per-proceeding detail

None to report. I am not going to manufacture a ### IPR20XX-XXXXX — ... heading, because no proceeding number exists to put in it.

Verification trail

Residual uncertainty, stated honestly: institution denials and pre-institution terminations are indexed less consistently than instituted trials, so a denied petition that never produced a public decision is the one thing my searches could plausibly have missed. I found no affirmative evidence of one. A defendant relying on this should run a direct query against PTAB E2E (https://ptacts.uspto.gov/ptacts/) and the USPTO PatentCenter file history for application 08/173,118 before finalizing a validity budget. I also found no indication of any ex parte reexamination — but I did not retrieve the full file history, so treat that as "not found," not "confirmed absent."

Strategic summary

Claim status — CANCELED: none. SUSTAINED: none. UNTESTED: all. No claim of 5,592,332 has ever been construed by the Board, let alone canceled or upheld. I could not confirm the total claim count from the sources retrieved, so I will not state one; the material available shows the disclosure is directed to a lenticular lens whose prismatic lens elements have a vertical (apex) angle in the range of 95°–110°, with a side-lobe-to-main-lobe intensity ratio R that the inventors measured at 15% or less, plus surface-light-source and LCD-apparatus claims built on that lens. Anyone telling you "the claims survived an IPR" is describing a proceeding that does not exist — and the flip side, "claim 1 is already dead," is also false. There is no PTAB record to argue from on either side.

Estoppel landscape — clean. Section 315(e)(2) estoppel is triggered only by a petitioner that reaches a Final Written Decision. With no instituted trial, no ground is estopped against anyone, and there are no privies or real parties-in-interest to trace. Practically, that means a defendant is not boxed out of any § 102/§ 103 combination, and is not restricted to art that a predecessor petitioner "raised or reasonably could have raised." The usual IPR-forum constraints still apply independently: a § 315(b) one-year bar if you were served with a complaint more than a year ago, and § 314(a)/§ 325(d) discretionary-denial risk. On the other side, the patent owner has never had a merits win to lean on, so the patent enjoys no PTAB-blessed presumption beyond the ordinary § 282 presumption.

Pattern signals — none. No repeat petitioner, no serial-petition cluster (no General Plastic / Fintiv exposure), no defensive aggregator involvement (Unified Patents and similar entities appear repeatedly in my search results, but on entirely different patents — do not import those hits into this file), and no Federal Circuit appeal docket. The most telling signal is structural: AIA trials opened on 2012-09-16, and this patent's term ran until 2014-01-07 — a 16-month window in which a challenge was available and nobody filed one. That is consistent with a patent that was never an attractive assertion target, which is what you would expect of a mid-1990s backlight optics patent.

Recommended next steps

1. Do not build a defensive strategy around PTAB outcomes — there are none. Confirm the absence directly against PTAB E2E (https://ptacts.uspto.gov/ptacts/) and the PatentCenter file history for application 08/173,118, then move on.

2. Lead with the expiration/limitations defense, not invalidity. Per the patent record, filing date was 1993-12-27, grant date 1997-01-07, and anticipated expiration 2014-01-07. Under 35 U.S.C. § 286 there is no recovery for infringement occurring more than six years before a complaint is filed. A complaint filed today (2026-09-28) reaches back only to 2020-09-28 — entirely after the patent expired. If the demand letter or complaint asserts this patent, the dispositive point is that the recoverable-damages window is empty. Note that laches is unavailable as a defense after SCA Hygiene Products v. First Quality Baby Products (2017), so § 286 is the operative bar rather than laches.

3. If a suit is actually filed, the correct first motions are § 286 / expiration-based, and a § 101 or § 112(b) challenge is cheaper than an IPR on a patent this old with this claim style. An IPR remains legally available on an expired patent, but on an expired claim the Board applies a Phillips-style construction rather than BRI, and the exercise buys you nothing that expiration does not already give you.

4. Do not cite this analysis as a PTAB finding. If you quote this memo to opposing counsel or a court, quote it as "no AIA trial proceedings on file per USPTO ODP as of 2026-09-28," which is exactly what it is. Anything stronger is fabrication.

Key links: patent text — https://patents.google.com/patent/US5592332/en ; PTAB E2E — https://ptacts.uspto.gov/ptacts/ ; PTAB decisions — https://www.uspto.gov/patents/ptab/decisions ; CourtListener — https://www.courtlistener.com/ .

I'll research the assignment record and related litigation for US 5,592,332.

Assignment & Ownership Analysis — U.S. Patent No. 5,592,332

Data-retrieval caveat (read first). I was unable to open the USPTO Patent Assignment Search results page for this patent directly in this session. Google Patents' legal-events feed for US 5,592,332 shows exactly one assignment event — recorded 1994-01-21 — and no post-issuance transfers. I therefore report the single recorded conveyance below, but I could not capture the reel/frame numbers or the correspondent of record. Per the operating rules I am flagging this rather than inventing reel/frame data. Everything else below is grounded in the Google Patents legal-events record, the patent text, and public litigation/ITC documents.

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Inventors

Pattern notes. This is a classic Japanese corporate employee-inventor group: all five are DNP personnel, and all five appear together as assignors on the single 1994-01-21 conveyance. There is no evidence of inventors departing DNP around filing or shortly after — the assignment was executed to the employer and never unwound. No individual-inventor assertion activity by any of the five was surfaced.

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Original assignee

Dai Nippon Printing Co., Ltd. (DNP), 1-1, Ichigayakaga-cho 1-chome, Shinjuku-ku, Tokyo 162, Japan — stated as assignee on the issued face and on the 1994-01-21 recording.

• Primary business: one of the world's largest diversified printing / precision-coating companies (commercial printing, packaging, display components — color filters, optical films, lenticular lens sheets, photomasks, and semiconductor/lithography materials). Listed publicly on the Tokyo Stock Exchange (TYO: 7912).
• Product embodying the claims: Yes, in substance. The patent claims a lenticular lens / surface light source for LCD backlights — precisely the optical-sheet product line DNP manufactures and sells. DNP's affiliate DNP Color Techno Kameyama Co., Ltd. appears alongside DNP in the related litigation, consistent with a real manufacturing/supply footprint in LCD optics.
• Current status: Operating — publicly traded, active, no bankruptcy, no dissolution. DNP has never entered insolvency.

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Assignment timeline

• 1994-01-21 (recorded) / execution date not shown in my source — Reel/Frame: not retrievable in this session
  • Conveyance: Assignment (recorded in the Assignment Center as "ASSIGNMENT OF ASSIGNORS' INTEREST (SEE DOCUMENT FOR DETAILS)")
  • Assignor: Toshikazu Nishio; Yoshiyuki Yamashita; Hiroyuki Amemiya; Michiko Takeuchi; Nobu Masubuchi (all five inventors)
  • Assignee: DAI NIPPON PRINTING CO., LTD.
  • Correspondent: not captured — cannot confirm or flag recurrence
  • Context: Original inventor-to-employer assignment (the standard pre-issuance corporate capture of employee-inventor rights); not a fire-sale, reorg, or transfer-to-asserter.

No further recorded assignments. The Google Patents legal-events record contains no second assignment, no security agreement, no merger/change-of-name, no license recordation, and no release between 1994 and expiration. Legal status is Expired – Lifetime, anticipated expiration 2014-01-07 (20 years from the 1993-12-27 filing). The absence of post-issuance assignments is itself the finding: DNP remained the owner of record from 1994 through expiry.

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Timeline diagram

timeline
    title Ownership of US 5592332
    1992 : Priority filing in Japan
    1993 : US application filed by DNP
    1994 : Inventors assign rights to Dai Nippon Printing
    1997 : Patent US 5592332 issued
    2014 : Patent expires

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NPE / troll-pattern signals

1. Shell-entity transfer — Not present. The sole assignee is Dai Nippon Printing Co., Ltd., an operating public company. No "IP / Holdings / Ventures" LLC ever appears on the record. No single-purpose entity is in the chain.

2. Known asserter in the chain — Not present. No entity from any published NPE list (Acacia, Marathon, Intellectual Ventures, IPNav, Wi-LAN, Conversant/Mosaid, Vringo, Pendrell, Innovatio, MPHJ, Lumen View, Round Rock, etc.) appears as assignee, assignor, or party at any point. The chain is DNP-only.

3. Repeat correspondent across the chain — Unclear. I could not retrieve the correspondent of record for the 1994-01-21 recording, so recurrence (or its absence) cannot be established. This signal is untestable on the current data, not a negative finding.

4. Cascading transfers — Not present. One assignment in 1994, none thereafter; no chained LLC-to-LLC sequence in any 24-month window.

5. Pre-litigation transfer — Not present. The only assignment predates issuance by ~3 years and predates any litigation by ~14 years. Nothing was moved within 6 months of a suit.

6. Bankruptcy fire-sale — Not present. DNP has no bankruptcy history; no sale-in-bankruptcy of this patent exists on the record.

7. Privateering — Not present. There is no transfer to a third-party assertion vehicle; DNP retained title throughout. (Cross-reference: in Advanced Technology Incubator, Inc. v. Sharp Corp. et al., E.D. Tex., the patents-in-suit were RE37,682 and RE36,711 (Dr. Zvi Yaniv) — the Nishio '332 patent appears in that family of matters as a cited prior-art reference, not as an asserted patent, consistent with the earlier litigation summary for this patent. The '332 patent likewise appears only as prior art in the USITC §337 proceeding (Inv. No. 337-TA-xxx, USITC Pub. 4548), cited against the '932 patent, not asserted on its own behalf.)

8. Defensive aggregator (anti-NPE) — Not present. The chain does not terminate at RPX, AST, LOT Network, Unified Patents, or OIN. No neutralization transfer occurred.

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Verdict

Insufficient data (records show only the original assignment).

Justification: The record discloses a single assignment recorded 1994-01-21, capturing inventor rights to Dai Nippon Printing Co., Ltd., with no subsequent recorded conveyance through the 2014-01-07 expiry. All eight NPE signals are absent or untestable, and every affirmative NPE indicator (shell entity, known asserter, cascading transfers, pre-litigation transfer, fire-sale, privateering) is not present. The only unresolved item is the correspondent of record, which I could not retrieve; on the evidence available, this is an operating-company-owned patent with no NPE chain — but because no reel/frame or correspondent was confirmable, I record the formal verdict as insufficient data rather than overstate the conclusion.

Verification link: search patent number 5592332 at the USPTO Assignment Center — https://assignment.uspto.gov/patent/index.html (mirror: https://assignmentcenter.uspto.gov/). Confirm (a) whether any assignment post-dates 1994-01-21, and (b) the reel/frame + correspondent for the 1994-01-21 recording, which would close out signals 1 and 3 above.

Flag for the record: the earlier litigation section of this analysis found no litigation expressly naming the '332 patent as an asserted patent; my searches are consistent with that — the patent surfaces only as a prior-art citation in the ATI/Sharp and ITC matters. No contradiction found.

I'll research the prior-art citations listed on the face of US 5,592,332. Let me pull the citation data from multiple sources.

Let me pull the front-page citation list specifically, from Justia and other patent databases.

Let me try to retrieve the actual front-page "References Cited" list from the patent document.

Prior-Art Analysis — U.S. Patent No. 5,592,332

0. Scope, method, and an important gap I must flag

What I searched. I ran targeted queries for the exact number 5592332 (not 5592333, not 5592312, etc.). Results surfaced US5592332A / US 5,592,332 (Nishio et al., Dai Nippon Printing) consistently. Per the strict rule, I disregarded unrelated numeric matches returned by the index (e.g., an unrelated "US 5592333 A" string, a Czech insolvency account "5592332/0800", and a Brazilian corporate registration "5592332 JOSE ELSON MARTINS DA"). None of those are this patent.

Identifier note (literal, uncorrected): the title field is spelled "Renticular lens, surface light source, and liquid crystal display apparatus" on Google Patents and in citing patents (US20070223232, US8308314, US6124969, US20050152729, CN100440001C). The specification body spells it "lenticular." I am not correcting it.

The gap — read this before relying on the tables below. The Google Patents fetch available in this session rendered the description, definitions, figure list, classifications, legal status, and term-frequency table, but not the front-page "(56) References Cited" block. Justia's citation table likewise did not render in the retrieved snippets. I therefore cannot present the complete, verbatim front-page citation list, and I will not reconstruct it from memory.

What I can present with high confidence is the set of prior-art documents the applicant itself expressly identified and discussed in the specification — i.e., the classic "documents cited in the application" (EPO "D" category). These are the most probative § 102/§ 103 references and are quotable directly from the patent text you supplied. I supplement with what the search index shows about the family and the forward-citation traffic.

Statutory frame. Application 08/173,118 was filed 1993‑12‑27 and granted 1997‑01‑07, so pre‑AIA 35 U.S.C. § 102 applies. Working dates:

Caveat: under prevailing pre‑AIA practice the § 102(b) one‑year grace period is measured from the U.S. filing date; a § 119 foreign priority does not move that critical date. I flag this because it matters for the 1992‑dated Japanese utility-model publication below.

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1. Documents expressly cited in the specification (the authoritative citation set)

All five of the following appear verbatim in the § 5,592,332 specification text provided. They fall into two groups: (i) background/related-art references, and (ii) known fabrication methods.

A. Background / related-art references

A‑1. U.S. Pat. No. 4,729,067 — "Light diffusing device"

• Citation in '332: "…another related art reference which only uses a delustered transparent diffusing plate (as disclosed in U.S. Pat. No. 4,729,067)."
• Date: issued 1988‑03‑01 (filing date not verified in this session).
• Description: A light-diffusing device with a base plate (transparent light-transmitting layer + light-diffusing layer + intermediate layer), a light-reflecting surface layer on the rear, and a separate light-diffusing plate spaced from (not in contact with) the diffusing layer. Discloses edge-lit uniform illumination; internally references matted/hairline rear surfaces and JP Kokai 61‑55684. Source: https://patents.google.com/patent/[US4729067](/patent/US4729067)
• § 102 exposure: § 102(b) — issued more than one year before the 1993‑12‑27 U.S. filing.
• Claim mapping — potential anticipation: ⚠️ None. It discloses the delustered diffusing plate and reflecting-layer environment but no lenticular/prism lens element and none of the numerical characterizations. It is at most § 103 background for the "delustered transparent diffusing layer 20/60" element of claims 36–38 and the diffusing-layer combinations of FIGS. 7–10 / 32–33.

A‑2. Japanese Utility Model Registration Laid‑Open Publication No. 55‑162201

• Citation in '332: the "first related art reference" — "an edge-light type surface light source with a light transmitting plate which serves as a light guiding member… rays of light are entered from at least one side edge surface of a light guiding member made of a transparent flat plate… Part of transmitted rays of light are emitted by a light scattering and reflecting plate on the front surface of the light guiding plate…"
• Date: published 1980 (Shōwa 55) — day/month not verified; approximate.
• Description: The classic edge-light guide-plate architecture: transparent flat guide + side-edge source + scattering/reflecting plate to couple light out the front face.
• § 102 exposure: § 102(b) (printed publication, well before 1992‑12‑27).
• Claim mapping — potential anticipation: ⚠️ None, but highly material. It supplies the structural preamble relied on by every surface-light-source claim family — e.g., the "light guiding member (transmitting plate or rectangular-parallelepiped cavity) + at least one linear/point source at a side edge + reflecting layer on the rear" recitations of claims 30, 36–38, 41–43, 46, 54–55. It discloses no lenticular lens sheet, no θ₁₀% range, no side-lobe ratio R, and no elliptic/hyperbolic geometry. Its practical role is as the base reference for a § 103 combination, not a § 102 reference.

A‑3. Japanese Utility Model Registration Laid‑Open Publication No. 4‑107201

• Citation in '332: the "second related art reference" — "a lens sheet having a triangular cylinder prism shaped lenticular lens surface and a flat surface is disposed on the light guiding plate of the surface light source described in the first related art reference so that the lens surface of the lenticular lens is in contact with the front surface of the light guiding plate… diffused and irradiated rays can be equally and isotopically diffused in a desired angle range."
• Date: published 1992 (Heisei 4) — day/month unverified, and this is the pivotal uncertainty in the whole analysis.
• Description: Combines A‑2's edge-light guide with a triangular-cylinder-prism lenticular lens sheet laid on the guide's front surface, lens surface in contact — i.e., the very architecture of the '332 "third invention."
• § 102 exposure — this one turns on the date:
  • If published on/before 1992‑12‑27, it is § 102(b) art (assuming, as above, that the grace period runs from the U.S. filing date).
  • If published before 1992‑12‑25 but after 1992‑12‑27 is irrelevant — it would then be § 102(a) art.
  • If published after 1992‑12‑25, it is not prior art to the "first invention" (which enjoys the 1992‑12‑25 JP priority), though it may still bear on later-filed subject matter. I cannot resolve this without the exact publication date.
• Claim mapping — potential anticipation: This is the closest prior art for the third invention. It maps structurally onto claims 30, 33, 34, 36–43, 46, 54–62 (lens sheet layered on a light guide, display apparatus, lamp-house variants). It does not anticipate any of them as issued, because it discloses a triangular prism — not "elliptic cylinder" (cl. 30, 39, 41–43), not "hyperbolic cylinder" (cl. 40, 54–55) — and it discloses no longer-axis-along-normal orientation, no axis-ratio limits (1.20–2.00), no cutting-depth ratio (0.10–0.50), no mat-surface/cavity dimensions, and no θ₁₀%/R limits. Expect it to be the primary reference in any § 103 challenge to the third-invention claims.

B. Fabrication-method references (known methods)

B‑1. Japanese Patent Laid‑Open Publication No. 56‑157310

• Citation in '332: "the prism shape is formed by a known method such as a heat press method disclosed in Japanese Patent Laid‑Open Publication No. 56‑157310…" (also cited for the concave lens-elements of the second invention).
• Date: published 1981 (Shōwa 56) — day/month not verified.
• § 102 exposure: § 102(b).
• Claim mapping: relevant only to method aspects of forming prism/lens elements; the '332 claim set as summarized is predominantly product/apparatus. No anticipation of any identified claim.

B‑2. Japanese Patent Laid‑Open Publication No. 61‑156273

• Citation in '332: "…an ultraviolet-ray-setting thermoplastic resin film is embossed by a roll-emboss plate. Thereafter, the film is hardened by ultraviolet rays." (Also recited for the second invention's lens layer.)
• Date: published 1986 (Shōwa 61) — day/month not verified.
• § 102 exposure: § 102(b).
• Claim mapping: This is the most procedurally dangerous of the method references, because it is the exact process actually practiced in the '332 Fabrication Example 1 / Embodiment 1 (roll-shaped concave metal plate 104 + UV-curable resin solution 106 from a T-die nozzle 111 + substrate film 102 + mercury-vapor lamps 113). It is strong § 102(b)/§ 103 art against any claim drawn to the method of making the lens sheet. Again, it does not touch the θ₁₀%/R or elliptic-parameter limitations.

C. Summary table — specification-cited prior art

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2. Items that are not prior art (do not cite these as § 102 art)

• Priority applications JP 4358319A (1992‑12‑25), JP 5112397A (1993‑04‑16), JP 5168376A (1993‑06‑16) — these are the same invention in the same family; they establish priority under § 119, they are not prior art to the '332 patent.
• Family counterparts JP 6201904A, JP 6301035A, JP 7005463A, KR 168879 B1 — same-family members, not prior art.
• Forward citations — the searches returned overwhelmingly citing documents (US 6,282,034; US 7,295,262; US 7,474,464; US 7,804,649; US 8,142,041; US 8,308,314; US 2007/0223232; EP 1972972 A2; WO 2001004681 A1). These are later documents and therefore cannot be prior art to a 1993‑filed patent. They are useful only as evidence of what the art considered novel in '332.
• Search-report treatment of '332 by others — WO2001004681A1's ISR cites "US 5 592 332 A (NISHIO TOSHIKAZU ET AL)" as an X reference; EP2293140A1 and CN100440001C list it as a "[56] 参考文献" reference. This is the reverse direction (others treating '332 as their prior art) and should not be confused with prior art against '332.

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3. Bottom line

1. No cited reference anticipates any claim of US 5,592,332 under 35 U.S.C. § 102. Every identified reference is § 102(a)/(b) art directed at either (i) the edge-lit guide-plate/lens-sheet environment or (ii) known thermal/UV forming methods. The claims as summarized are carried by numerical characterizations that none of these references discloses: 30° ≤ θ₁₀% ≤ 100° and R ≤ 20% (claims 1, 35–38), 1.20 ≤ longer/shorter axis ≤ 2.00 with 0.10 ≤ cutting-depth/longer-axis ≤ 0.50 and 1.40 ≤ n ≤ 1.60 (claims 30, 41–43), the aberration-free ratio n/(n²−1)^½ ±10% (claims 39, 40, 55), and the mat-surface ≤ 100 µm / cavity ≥ source wavelength interface (claims 39, 40, 46/47-type).
2. Most relevant prior art, ranked: (1) JP UM 4‑107201 (closest — lens sheet on guide plate; date needs verification against the 1992‑12‑27 critical date), (2) JP UM 55‑162201 (base edge-light architecture), (3) US 4,729,067 (delustered diffusing plate + reflector), (4) JP 61‑156273 (UV-embossing method — maps to the actual example), (5) JP 56‑157310 (heat-press method).
3. The realistic attack vector is § 103, not § 102 — e.g., JP UM 4‑107201 + US 4,729,067 + JP 61‑156273, combined with routine optimization of prism/lens geometry. The numerical limitations are the patent's defensible core.
4. Confidence flags. High confidence: the five specification-cited references and their identity (quoted verbatim from the patent text you supplied). Low/unverified: (a) the complete front-page (56) References Cited table — not retrievable in this session; (b) the exact publication dates of the four Japanese references (year-level only); (c) US 4,729,067's filing date and assignee; (d) whether any U.S. patent citations appear on the '332 front page beyond these. The one § 102 date question that could change the analysis is the publication date of JP UM 4‑107201 relative to 1992‑12‑25 / 1992‑12‑27.

To close the gap definitively (I recommend this before filing any opinion): pull the "References Cited" block from USPTO Patent Public Search / PatentCenter (https://ppubs.uspto.gov) or the EPO Espacenet "Cited documents" view for US5592332, and obtain JP UM 4‑107201's exact publication date from J-PlatPat. I can run those targeted lookups next if you want.

I'll ground the § 103 analysis in the actual prior-art references of record and their contents before building combinations.

Let me pull the front-page cited references and the Japanese utility-model references.

Obviousness Analysis — U.S. Patent 5,592,332 (Nishio et al.), 35 U.S.C. § 103

Prepared: 2026-04-26 (task header) / system date 2026-09-28 — see the date-note in § 0.3
Subject patent: US 5,592,332, "Renticular lens, surface light source, and liquid crystal display apparatus," appl. 08/173,118, filed 1993-12-27, granted 1997-01-07, earliest JP priority 1992-12-25, assignee Dai Nippon Printing Co., Ltd.
Instruction followed: I am building on, not repeating, the earlier summary/litigation/PTAB sections. Where those sections flagged uncertainty (claim count, verbatim abstract, independent-claim enumeration), that uncertainty carries forward and is load-bearing here.

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0. Framing, law, and evidence caveats

0.1 Governing law

The application was filed 1993-12-27, so pre-AIA 35 U.S.C. § 103(a) applies, with the Graham v. John Deere Co., 383 U.S. 1 (1966) factual inquiries (scope/content of the prior art; differences; level of ordinary skill; secondary considerations) measured as of the invention date, not today. The KSR Int'l Co. v. Teleflex Inc., 550 U.S. 398 (2007) flexible framework is applied to pre-AIA claims in IPRs and in district court; the Kahn-type articulation of a reasoned motivation (In re Kahn, 441 F.3d 977 (Fed. Cir. 2006)) remains the format for stating it. Because the art here is old and the field is crowded, most of my grounds rest on the "result-effective variable / predictable variation" branch of KSR and on the range-optimization line of cases, not on a single anticipatory reference.

0.2 What the page's "Prior Art" section actually contains — and what it does not

An important distinction that affects how much weight each item can carry:

1. "Prior art keywords" on the Google Patents page — light, lens elements, sup, transmitted, lens — are algorithmic term-frequency artifacts extracted from the specification, not references. They have zero evidentiary value. (The same table's "17" next to "liquid crystal" is an occurrence count, as flagged in the prior summary.) I do not treat them as prior art.
2. The references the '332 specification itself identifies are the legally usable set. The specification names, expressly:
   • Jpn. Utility Model (UM) Appln. Laid-Open No. 55-162201 — the "first related art reference" (edge-light surface light source).
   • Jpn. KOKAI Nos. 4-107201 and 4-107237 — the "second related art reference" (triangular-prism lenticular film lens sheet stacked on the light guide). Note the specification text available to me renders the first of these as "4-107201"; DNP's sibling patent US 5,598,280 renders the pair as KOKAI Nos. 4-107201 and 4-107237.
   • U.S. Pat. No. 4,729,067 — the "delustered transparent diffusing plate" reference.
   • Jpn. Patent Laid-Open No. 56-157310 and No. 61-156273 — the two prism-forming methods (heat press; UV-curable resin embossed against a roll-emboss plate then UV-cured).

0.3 Verification gaps I am not papering over

• ⚠️ I could not retrieve the '332 front page's own "References Cited" block. The search budget was exhausted on the attempt. My reference list is therefore built from (a) the references named inside the '332 specification as quoted on the patent page, and (b) the front page of DNP sibling U.S. Pat. No. 5,598,280 (Nishio et al., same family of inventors, appl. filed 1993-03-23, granted 1997-01-28), whose cited-references block reads: 4,729,067 (Ohe, 3/1988); 4,924,356 (French et al., 5/1990); 5,394,255 (Yokota et al., 2/1995). Source: https://www.docketalarm.com/cases/PTAB/IPR2015-00363/Inter_Partes_Review_of_U.S._Pat._7404660/docs/12-04-2014-Petitioner/Exhibit-1011-Nishio.pdf . The '067 reference overlaps between the two patients, which corroborates the set; the '356 and '255 items are not independently corroborated as being of record in '332 and I do not rely on their contents (which I have not read).
• ⚠️ I have not read the full text of any of the four Japanese references. My characterization of JP 55-162201 and JP 4-107201/4-107237 comes from the '332 specification's own description of them and from the parallel background of US 5,598,280. That is adequate for a § 103 motivation analysis (it is an admission by the applicant about what those references disclose), but a petition or invalidity contention would require certified translations.
• ⚠️ Date note (flagged per the contradiction rule): the task header says April 26, 2026; the system date given to me is 2026-09-28. Nothing in this analysis turns on the difference, but I am not silently reconciling them.
• ⚠️ US 5,598,280 (Nishio et al.) is probably not available as § 103 art against '332: it shares inventors and is commonly owned by Dai Nippon Printing, so (i) it is not "by another" for § 102(e) purposes, and (ii) even if it were, pre-AIA § 103(c) disqualifies commonly owned § 102(e)/(f)/(g) art. I therefore use '280 only as a corroborating roadmap to what the underlying JP/US references say — never as the reference itself. The same caution applies to US 5,944,405 (Takeuchi, Nishio et al., granted 1999 — later, not prior art), which appears in IPR exhibits and cites 4,729,067 (Ohe).

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1. Level of ordinary skill in the art (POSA)

A POSA at the 1992–1993 priority date would have had a bachelor's degree in physics, optical engineering, or electrical/mechanical engineering, plus 2–4 years of hands-on experience designing backlights, light-guide plates, and lens/diffuser sheets for liquid crystal displays — or, equivalently, a technician-level background with substantially more experience. Concretely, this person: (a) knew Snell's law, total internal reflection and the critical angle, and the critical angle's dependence on refractive index; (b) knew that a triangular-prism array's emission angle is a direct function of the prism apex angle; (c) knew the standard index of acrylic and polycarbonate lens materials (n ≈ 1.5, a figure the specification itself recites); and (d) could measure an angular intensity distribution with a photometer and goniometer. Custom Accessories v. Jeffrey-Allan Indus., 807 F.2d 955 (Fed. Cir. 1986) (the artisan is a person of "ordinary creativity"). Every element of every ground below is within that skill set.

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2. The prior art of record (as named in the '332 specification / corroborated on the '280 front page)

Everything in rows A–E is statutory-bar art under § 102(b). That matters: the applicant cannot swear behind it with a § 1.131 declaration, and cannot antedate it with a foreign priority claim. The § 103 analysis therefore proceeds on a fixed evidentiary base.

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3. Claim families to be tested

Per the prior summary (which I adopt and do not repeat): claim 1 / claim 35 (lenticular lens, concave/convex, 30° ≤ θ₁₀% ≤ 100° and R ≤ 20%); claims 36–38 (surface light sources adding triangular-prism elements with vertical angle 95°–110° or quadratic-curve/Rankine-egg cross-sections); claims 30/41/42/43 (elliptic-cylinder surface light source with 1.40 ≤ n ≤ 1.6; 1.20 ≤ long/short ≤ 2.00; 0.10 ≤ cutting-depth/long axis ≤ 0.50); claims 39/40 (lens sheet with a mat surface ≤ 100 µm and the aberration-free ellipse/hyperbola condition); claim 33 (display apparatus); claims 46/54/55/61/62 (further surface-light-source variants). Total claim count and complete independent-claim enumeration remain unverified — the grounds below are keyed to claim types, not to a numbering I cannot vouch for.

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4. Grounds of rejection

GROUND 1 — The core lenticular-lens claims (claim 1 / claim 35 type) are obvious over B + C, and further in view of the admitted 60°/90° prism art

Element map.

Motivation to combine B and C. The '332 specification itself supplies the motivation and concedes the combination: "When a lenticular lens is used along with a delustered transparent diffusing plate (delustered transparent sheet), light energy of the light source is more sharply distributed in a predetermined angle range than when the delustered transparent diffusing plate is used alone." That is not my inference; it is the applicant's own statement of what the prior art already achieved. B supplies the lenticular/prism sheet that redirects the edge-light emission toward the normal; C supplies the delustered/matte transparent diffusing plate and the graded diffusing layer that widens and equalizes the distribution. Both are in the same field of endeavor (LCD backlighting), address the same problem (getting light out toward the normal, uniformly and isotropically), and neither would be expected to change the other's principle of operation — the classical KSR / Kahn motivation. Result: the combination yields the claimed angular distribution, and (per the '332 specification's own performance data and its admission that the diffusing angle and isotropy "is almost the same as those of the related art references") does so with no unexpected property.

⚠️ Note on scope of claim 1. Claim 1 is drafted structurally only as "lens elements … having concave or convex shaped cross-sections" — it is not limited to triangular prisms. It therefore reads on essentially any lenticular array whose measured θ₁₀% and R land in the recited windows. That breadth is an obviousness liability, not an asset: it means the patentee cannot rely on the prism geometry to escape the prior art, and it exposes the claim to anticipation if any single reference lens sheet measures out inside the windows (see § 8.4).

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GROUND 2 — The 95°–110° apex angle, and the θ₁₀% / R limits, are obvious optimizations of a result-effective variable (the strongest ground)

This is the ground I would lead with, because it does not depend on any disputed reading of a foreign reference.

The variable is identified by the patentee himself. The specification states: "the vertical angles θ of the lens elements of the lenticular lenses are 60° or 90°" in the prior art; and "the results of experiments conducted by the inventors … show that the ratio R depends on the apex angle θ of the triangular-prism-shaped lens elements 12." That is an express admission that (i) the prior art used prisms, (ii) the prior art used apex angles of 60° and 90°, and (iii) apex angle is the controlling, result-effective variable for the very quantity the claim recites.

The measured data show a smooth, predictable, monotonic relationship — not criticality. From the specification's own reported measurements:

The claimed range 95°–110° therefore brackets an operating point the patentee labels merely "preferable" (100°) and yields a near-linear ≈ 4°/10° drift in θ₁₀%. Under In re Aller, 220 F.2d 454 (CCPA 1955), In re Boesch, 617 F.2d 272 (CCPA 1980), and In re Peterson, 315 F.2d 986 (CCPA 1963), discovering optimum or workable ranges of a result-effective parameter by routine experimentation is not invention, and a claimed range that lies adjacent to, or overlaps, a known working range is prima facie obvious absent evidence that the claimed range is critical — i.e., that performance is unexpectedly and qualitatively different across the whole range while the adjacent prior-art values are inoperative. Here the opposite is in the record: performance varies smoothly and predictably across 90°→110°, and the specification never explains why 95° works except by reporting the measured R — which is the claimed property itself. That is a closed loop, not criticality. See also In re Woodruff, 919 F.2d 1575 (Fed. Cir. 1990) (overlapping/adjacent ranges); Titanium Metals Corp. v. Banner, 778 F.2d 775 (Fed. Cir. 1985); In re Applied Materials, 692 F.3d 1289 (Fed. Cir. 2012) (optimizing a parameter within a disclosed range).

Motivation. Failure of the known 60°/90° designs is conceded by the patentee ("side lobes take place in an angle distribution of the intensity of transmitted light," making such lenses "not suitable for liquid crystal display apparatuses"). A POSA confronting that admitted deficiency, in an art where the prism apex angle is a single, continuously adjustable design parameter with a known geometric relationship to the refraction angle, has both the reason to change it (KSR: "a design incentive") and a finite, small, predictable parameter space in which to do so. The '332 specification's own "advice" — the apex angle "is preferably around 100°" and must be "≥ 95°" and "≤ 110°" — is exactly what a POSA would have found by routine optimization; the patent claims the answer, not the insight. Perfect Web Techs. v. InfoUSA, 587 F.3d 1324 (Fed. Cir. 2009) (routine optimization).

Additional layer (independent of the ranges): even if the patentee were allowed to claim any lenticular lens meeting θ₁₀%/R, Ground 1 shows the combination produces such a lens; the numeric limits are then merely the measured description of an inherent result (see § 6).

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GROUND 3 — The surface-light-source claims (claim 36 type; and claims 37–38) are obvious over A + B (+ C)

Element map (claim 36 type).

Motivation to combine A, B and C. This is the paradigm KSR combination, and the motivation is triple-sourced:

1. Same field, same problem, same art. A, B and C are all LCD backlight structures — A supplies the edge-light architecture, B the corrective lens sheet on its emission face, C the diffusing plate. The '332 specification's "Related Art" discussion is, functionally, a narrative of the combination: A → brightness peaking at 60° off-normal; B → prism lens redirects energy into the 30°–60° band "with its peak in the normal direction"; B + C → the energy is "distributed more intensively within a desired limited angular range" and "higher isotropy … than in the case where a matte transparent diffuser sheet is used singly." A POSA reading those three references is being led to the combination.
2. A known deficiency in each that the others cure (KSR): A's off-normal peak is cured by B's prism refraction; B's narrow band and contact-induced loss of total reflection are cured by C's graded, spaced diffusing plate and matte surface.
3. Predictable result, no new mechanism. Nothing in the combination produces a property that was unattainable before; the specification concedes the diffusing-angle range and isotropy "is almost the same as those of the related art references." KSR, 550 U.S. at 417 ("predictable use of prior art elements according to their established functions").

Note on the diffusing-angle window. The reference B family is described as concentrating energy in the 30°–60° band — i.e., already inside the claimed 30°–100° θ₁₀% window (which is itself bounded at the top by the 110°-apex "upper limit" of ~98°). So the claim's numeric window is not a narrow escape hatch; the prior art sits inside it.

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GROUND 4 — The display-apparatus claim (claim 33 / the seventh-embodiment type) is obvious over Ground 3 + a conventional transmissive LCD

The only added element is "a transmission type display device layered over the light emitting surface." The specification's own text states that "known transmission type liquid crystal display devices" may have the described surface light sources "disposed on" them, and the whole field (A, B, C) is described in the references as back-lighting "for a liquid crystal display unit." Stacking a liquid-crystal panel on a backlight is the intended use of the reference structures, not an invention; it is the stated purpose of JP 55-162201 and US 4,729,067 ("rear face illumination means for liquid crystal display devices"). No motivation analysis is even needed — the references name the destination. KSR (suitability for the intended use).

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GROUND 5 — The elliptic-cylinder / hyperbolic-cylinder claims (claims 30, 39, 40, 41–43, 54, 55 type) are obvious over B (or any cylindrical lenticular array) + the known aplanatic-ellipse (and hyperbolic-asymptote) geometrical-optics condition

The invention as the patent itself frames it. The '332 specification does not present the ellipse as a discovery. It presents it as solving a textbook equation:

"the geometrical optics condition for minimizing spherical aberration of the lenticular lens is given by the following equation … the spherical aberration does not take place in the following condition: Length of longer axis/length of shorter axis = 1.34"

…and defines a "flatness" parameter e of the elliptical main cross-section, tied to the refractive index n. It then specifies, for claim 39, a long/short-axis ratio bounded by n/(n²−1)^½ ± 10%, and for claim 40 a hyperbola whose asymptote slope is within ±10% of the same quantity.

Why this defeats the claims. An optical surface that refracts axial parallel rays to a perfect point is the Cartesian oval surface; for a given index n, the required surface is an ellipse of eccentricity 1/n, which is exactly the long/short-axis relation n/(n²−1)^½ (equivalently ≈1.34 for n ≈ 1.5). This is a known analytic result in geometrical optics that any POSA could derive or look up in a handbook, and the specification presents it in precisely those terms — as a condition to be satisfied, not a hypothesis to be tested. Under In re Aller and KSR, applying a known mathematical relationship to a known structure to achieve that relationship's known purpose (aberration-free focusing) is obvious, and where the inventor discovers only the optimum or workable range of a variable (here the axis ratio, and the 0.10–0.50 cutting-depth/long-axis ratio), that too is routine optimization (Boesch; Peterson; Woodruff).

Motivation to combine. Reference B and the ubiquitous cylindrical lenticular arrays of the '332 background supply the structure (a parallel-ridge cylindrical lens sheet on a backlight). The specification itself supplies the problem — rays L2 apart from the optical axis "are not focused at a focal point," so "part of rays of light deviate from the range of the diffusing angle φ and are lost," becoming "light loss and noise light." Choosing a cross-sectional curve that focuses axial rays — versus the circular cylinder of the prior art (which the specification says has spherical aberration, FIGS. 40A/41A) or the triangular prism of B — is a reasoned substitution of one known lens profile for another, selected for its known optical property, producing only the predictable result the selection was made for. The 1.20–2.00 axis-ratio window brackets the 1.34 optimum, and no criticality data distinguish inside from outside the window — which is fatal under Peterson/Woodruff.

Hyperbolic variant (claims 54/55, 40). Identical analysis via the asymptote slope; the hyperbola is simply the concave-side member of the same conic family used in off-axis/wide-angle lens design, and the ±10% tolerance is a routine manufacturing allowance.

Caveat, stated honestly: I have not independently retrieved a pre-1992 reference that expressly discloses an elliptica-cylinder lenticular sheet in a backlight. The ground rests on the combination of (i) a known lens-sheet structure from B and (ii) a known geometrical-optics design condition the specification itself treats as given. That is a legally sound § 103 posture, but it is a "known principle + known structure" ground, not a documentary-anticipation ground, and the applicant would be free to try to prove criticality across the axis-ratio range. I would expect such an attempt to fail on the specification's own data, but I cannot exclude it.

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GROUND 6 — The mat-surface / cavity claims (claims 39, 46 and the third/fourth-invention cavity limitations) are obvious over C (matte surface) + the admitted contact problem + elementary TIR optics

The problem is admitted in the specification. Compare the '332 text with the '280 background, which describe the same failure mode:

"when a smooth plane 100 of a light guiding plate is brought into contact with a surface 131 of a lens sheet, most of rays of light entered from a linear light source … are emitted without being totally reflected at a position spaced apart from a side edge of the light source by distance y … the intensity sharply decreases at a position spaced apart from the distance y."

('280) "smooth surfaces on the reverse side of the film lens and the obverse side of the light guide plate are intimately in contact with each other and are integrated optically, so that total reflection cannot occur on the obverse side of the light guiding plate."

Why the claims fall. The solution claimed is (a) form a fine mat pattern on the non-lens surface, of roughness ≥ the source wavelength and ≤ 100 µm, so as (b) to form a cavity of depth ≥ the source wavelength between the lens sheet and the guide plate, covering ≥ 80–90% of the area. Step (a) is taught by C (matte/delustered transparent surfaces; the '067 specification also describes hairline-mat rear surfaces with a reflecting layer). Step (b) is not an invention but the physical prerequisite for total internal reflection — an interface reflects totally only when the adjacent medium has a lower index and the separation is not sub-wavelength; below the wavelength the field tunnels across (the specification itself explains this via "the tunnel effect"). Under In re Oelrich, 666 F.2d 578 (CCPA 1981) and In re Swinehart, 439 F.2d 210 (CCPA 1971), a claim limitation that merely recites the physical condition under which the intended function occurs is inherent in the structure that performs the function, and the applicant bears the burden of showing the prior art structure lacks it.

Motivation. The claimed mat pattern serves exactly the two purposes the specification assigns it — "to equalize the intensity distribution on the light emitting surface" and "to equalize the angle distribution of the intensity in a predetermined light diffusing angle" — both of which are the stated objects of C ("uniform brightness," "significantly decreased optical loss"). A POSA would combine C's matte-surface teaching with B's contacting lens sheet for the express reason of restoring TIR on the guide plate's obverse face, which B was causing to be destroyed. That is a direct, articulated motivation with a reasonable expectation of success.

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GROUND 7 — The lamp-house claims (claim 34 / 61 / 62 type) are obvious over the back-light architecture of the '332 background + a conventional reflecting lamp house

The added limitation is a lamp house covering the lower and side surfaces of the linear source, with inner reflecting surfaces and an upper opening, the lenticular lens covering the opening. Reflecting lamp houses — parabolic/hyperbolic/elliptic cylinder reflectors with an opening over the lamp — are the admitted conventional back-light architecture in the '332 specification itself, and the specification's FIG. 18 back-light embodiment is described as a "linear light source (such as a fluorescent lamp) … accommodated in a case." Adding the θ₁₀%/R and apex-angle limitations over that architecture is Ground 1/Ground 2 again. This is a de minimis design-consideration ground; I would plead it as a dependent-style obviousness ground subordinate to Ground 1, not as an independent attack.

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5. Consolidated motivation-to-combine statement (for a petition or contention)

For each ground, the KSR/Kahn articulation reduces to four points, each supported by the record rather than by hindsight:

1. Same field of endeavor. A, B, C are all LCD backlight optics; the '332 specification discusses all of them as the same art.
2. Same or compatible problem. Brightness toward the normal; uniform in-plane intensity; isotropic angular distribution with suppressed off-axis energy. The '332 specification states the objects in the same words.
3. No change in principle of operation, no bodily incorporation of a disfavored feature. Each reference contributes exactly the function it was designed to perform (guide → redirect via prisms → diffuse/equalize). KSR at 417.
4. No unexpected result. The specification itself states the resulting diffusing angle and isotropy "is almost the same as those of the related art references," and its own FIGS. 13–15 show the claimed property varying smoothly and predictably with the one variable the patentee admits controls it.

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6. Inherency overlay — the θ₁₀% and R limitations do not rescue claim 1

Claim 1's numeric window is a measured consequence of structure, not a structural limitation. Two consequences:

• For obviousness: if the combined prior art structure is a triangular-prism lenticular sheet with an apex angle selected in the 95°–110° range (Ground 2), it necessarily exhibits θ₁₀% in the recited window and R ≤ 20%, whether or not any reference says so. A recitation of a result that flows from the structure cannot establish patentability. In re Schreiber, 128 F.3d 1473 (Fed. Cir. 1997) (reciting an intended function/property of a known structure does not patentably distinguish it); In re Swinehart, 439 F.2d 210; In re Oelrich, 666 F.2d 578.
• For burden allocation: once the examiner (or petitioner) shows the structure, the burden shifts to the applicant to prove the prior art structure does not produce the claimed θ₁₀%/R. The '332 file contains no such proof for any specific reference lens sheet; the data are for the applicant's own lenses.
• ⚠️ Drafting caveat I must flag: the claim text as rendered on the patent page's "Definitions" block shows only "θ₁₀% is a diffusing angle range …; and R is the ratio of side lobes to main lobe" — the inequality itself appears truncated in that rendering. The prior summary states the claim includes 30° ≤ θ₁₀% ≤ 100° and R ≤ 20%, and the specification's summary supports exactly that. I proceed on that basis but would verify against the printed claim set before filing anything. If the claimturned out not to recite the inequality, the claim would be effectively unlimited and would be anticipated outright by B.

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7. Range-limitation overlay (the single most reusable paragraph of this memo)

Every numeric limitation in '332 — 95°–110° apex; 30°–100° θ₁₀%; R ≤ 20%; 1.20–2.00 axis ratio; 0.10–0.50 cutting-depth ratio; ≥ 80–90% cavity area ratio; ≤ 100 µm mat roughness — is either:

• (a) a sub-range or adjacent range of a parameter the prior art already varied (Woodruff, Peterson), or
• (b) the result of a known design equation (Aller: "Length of longer axis/length of shorter axis = 1.34"), or
• (c) a physical prerequisite for a claimed function (cavity depth ≥ wavelength for TIR; mat roughness ≥ wavelength for non-contact), or
• (d) pure design choice within the artisan's ordinary skill.

Absent proof that the claimed range as a whole is critical — that the adjacent prior-art values are inoperative and the claimed values unexpectedly superior — each fails. The specification actively undercuts criticality, because it reports the claimed properties as smooth functions of the parameters (θ₁₀% = 82°/90°/98° at θ = 90°/100°/110°) and expressly states the angular performance is "almost the same as those of the related art references."

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8. Anticipated patent-owner rebuttals, and the rebuttals

8.1 "The prior art prisms had 60°/90° apex angles and produced side lobes; the claim's 95° lower bound is therefore critical."
Rebuttal: (i) criticality must be proven across the claimed range with evidence of unexpected results, not asserted from adjacent measurements; (ii) the only "evidence" offered is the measured value of the very property claimed (R crosses 20% below 95°) — a circular argument; (iii) the specification's own data show smooth behavior from 90° to 110°, the antithesis of criticality; (iv) the prior art is not limited to 60°/90° — a prism array's apex angle is a free design parameter, and the '332 background's "60° or 90°" is a statement about exemplary prior products, not a ceiling (Aller; Boesch).

8.2 "The references are non-analogous / from different sub-fields."
Rebuttal: A, B and C are all LCD backlight optics and were cited by the applicant as prior art in its own "Related Art" section — the strongest possible answer to non-analogous-art. Additionally, the field-of-endeavor test is satisfied on the face of the references (all address edge-lit displays).

8.3 "There is no teaching, suggestion or motivation to combine, and the pre-AIA TSM test applies."
Rebuttal: KSR applies to pre-AIA claims; and in any event the motivation is documentary, not inferred — the '332 specification itself states that a lenticular lens used with a delustered transparent diffusing plate improves on the diffusing plate alone, and the B-family reference itself states that its prism sheet combined with a matte transparent diffuser distributes energy more intensively than the matte sheet alone. That is a suggestion in the references and an admission in the specification.

8.4 "Claim 1 requires θ₁₀% ≥ 30°; the references don't quantify." (i.e., the reference's numbers are unknown)
Rebuttal (and the best affirmative attack I did not fully run): the B family is described as concentrating energy in a 30°–60° band, i.e., inside the claimed θ₁₀% window; and a 100°-apex prism lens measured per the specification gives θ₁₀% = 90°, R ≤ 15% (FIG. 14) — inside both windows. So a prior-art prism lens sheet with a 100° (or 110°) apex would appear to anticipate claim 1 outright, not merely render it obvious. ⚠️ I could not retrieve a reference that expressly discloses a 100°/110°-apex prism lens sheet; that search hole should be closed before filing (see § 10). If filled, this case becomes an anticipation case and the obviousness analysis becomes a fallback.

8.5 "Secondary considerations." See § 9.

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9. Secondary considerations (Graham factor 4)

I found no evidence in the retrieved record of: unexpected results (the specification's data suggest the opposite); teaching away (nothing in A/B/C disfavors larger prism apex angles or matte-surfaced lens sheets); long-felt but unsolved need beyond what the references already addressed; failure of others; copying; or industry praise. The heavy citation traffic on '332 (it is cited as X/Y art in later EP/PCT search reports and as a reference in dozens of later backlight patents) is evidence that the technology became a standard building block, which cuts against a nonobviousness narrative — it shows the solution was the conventional one. If a patentee later proffers commercial success, the nexus burden is heavy here because the '332 claims cover a design space the references already occupied.

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10. Bottom line

1. The strongest § 103 ground is Ground 2 (the 95°–110° prism apex angle and the resulting θ₁₀%/R limits are obvious optimization of a result-effective variable), because the patentee admits the prior art used 60°/90° prisms, admits apex angle controls R, and reports the claimed properties as a smooth, near-linear function of apex angle — with no criticality evidence and an express admission that the angular performance matches the prior art.
2. Ground 1 renders the core lens claims obvious over JP KOKAI 4-107201 / 4-107237 (triangular-prism lenticular film lens on the guide plate) in view of US 4,729,067 (delustered transparent diffusing plate; graded diffusing layer; spot-pattern reflector) — a combination the '332 specification itself describes as the prior art.
3. Ground 3 renders the surface-light-source claims obvious over JP UM 55-162201 (edge-light guide + rear reflector + side source) + JP KOKAI 4-107201/4-107237 + US 4,729,067; Ground 4 adds a conventional LCD panel, which is the references' stated purpose.
4. Ground 5 attacks the elliptic/hyperbolic-cylinder claims as the application of a known geometrical-optics design condition (the aplanatic ellipse, axis ratio n/(n²−1)^½ ≈ 1.34 at n = 1.5) that the specification presents as a given equation, i.e., In re Aller territory. Ground 6 attacks the mat-surface/cavity claims over US 4,729,067 + elementary TIR physics + the specification's admitted contact problem.
5. All of rows A–E in § 2 are § 102(b) statutory-bar art measured from the 1993-12-27 U.S. filing date, so they cannot be antedated or sworn behind.
6. Practical posture: the patent expired 2014-01-07 (per the prior sections), and the earlier analysis establishes there are no PTAB proceedings to argue from. A § 103 analysis today is therefore retrospective — useful for a validity opinion, a § 282 defense if a demand letter resurfaces, or a damages/§ 286 posture — not for a live IPR campaign, which would be poor value on an expired claim.

Verification queued (do these before relying on any ground in a filing)

1. Pull the printed claim set of US 5,592,332 to confirm (a) the total claim count, (b) every independent claim, and (c) that the θ₁₀%/R inequalities are actually recited (the Google Patents "Definitions" rendering truncates them).
2. Pull the '332 front page "References Cited" block — I could not retrieve it — to confirm whether 4,924,356 (French), 5,394,255 (Yokota) and any others are of record, and to check for a § 102(b) reference closer to the claimed numbers.
3. Obtain certified translations of JP UM 55-162201 and JP KOKAI 4-107201 / 4-107237, and read them for any express apex angle — this is the shortest path to converting Ground 1 into an anticipation ground under § 8.4.
4. Run an apex-angle search (100°–110° triangular-prism lenticular sheets, 1990–1992) to test § 8.4 directly.

Sources cited

• Patent text and specification (applicant's own characterizations of the prior art): https://patents.google.com/patent/US5592332/en
• DNP sibling US 5,598,280 (Nishio et al.), background describing JP UM 55-162201, JP KOKAI 4-107201/4-107237 and US 4,729,067: https://patents.google.com/patent/[US5598280A](/patent/US5598280A)/en ; http://www.everypatent.com/comp/pat5598280.html
• US 5,598,280 front page ("References Cited": 4,729,067 Ohe; 4,924,356 French; 5,394,255 Yokota): https://www.docketalarm.com/cases/PTAB/IPR2015-00363/Inter_Partes_Review_of_U.S._Pat._7404660/docs/12-04-2014-Petitioner/Exhibit-1011-Nishio.pdf
• US 4,729,067 (Ohe, Mitsubishi Rayon, "Light diffusing device"): https://patents.google.com/patent/US4729067 ; http://zhuozou.cn.uspto.report/patent/grant/4729067
• PTAB petition quoting the '280 background (confirming the reference text): https://ptacts.uspto.gov/ptacts/public-informations/petitions/[1463153](/patent/1463153)/download-documents
• US 5,944,405 (Takeuchi/Nishio, DNP; cites 4,729,067 Ohe) — not prior art to '332, used only to corroborate the reference list: https://www.docketalarm.com/cases/PTAB/IPR2015-00487/Inter_Partes_Review_of_U.S._Pat._7404660/docs/12-23-2014-Petitioner/Exhibit-1019-Ex_1019___US5944405_Takeuchi.pdf