US 4729068

I'll search for authoritative information on US patent 4,729,068.

US Patent 4,729,068 — Verified Summary

I searched for this exact number and did not auto-correct it. Below is what the authoritative sources confirm, plus a note on litigation.

Bibliographic data

Source: https://patents.google.com/patent/US4729068/en ; https://www.freepatentsonline.com/4729068.html

Abstract (verbatim)

"A light diffusing device useful for evenly illuminating a relatively large area comprises (1) a light source member and (2) a light diffusing member comprising (A) a base plate having (a) a transparent light transmitting layer with at least one light incident edge face thereof, (b) a light diffusing layer formed on the front surface of the transparent light transmitting layer, (c) an intermediate layer formed between the transparent light transmitting layer and the light diffusing layer, and (d) a light reflecting surface layer formed on a rear surface of the transparent light transmitting layer; (B) a light diffusing plate superimposed over the base plate; and (C) a light reflecting film arranged between the base plate and the light diffusing plate and effective for evenly distributing light irradiated from the light diffusing layer into the light diffusing plate."

Independent claim — plain-language overview

The patent has 7 claims, of which only claim 1 is independent. (Claims 2–7 are dependent; note that claim 3 recites "as claimed in claim 1" while referring to the "light reflecting edge face layers" that are actually introduced in claim 2 — an apparent dependency inconsistency in the printed text.)

Claim 1 covers an edge-lit (backlight) light-diffusing apparatus made of two cooperating assemblies:

1. A light source member — e.g., a fluorescent tube placed at the edge of a panel.

2. A light diffusing member, which itself is a stack of:

   • (A) A base plate having four cooperating parts:
     • a transparent light-transmitting layer whose edge face faces the lamp (light enters through the edge, not the back);
     • a light-diffusing layer on the front surface of that transparent layer;
     • an intermediate layer sandwiched between the transparent layer and the diffusing layer;
     • a light-reflecting surface layer on the rear surface of the transparent layer (so light is bounced back upward instead of escaping out the back).
   • (B) A light-diffusing plate placed over the base plate.
   • (C) A light-reflecting film positioned between the base plate's diffusing layer and the diffusing plate without touching either one (the specification explains it is separated from both by very thin air gaps).

   The distinguishing functional limitation of claim 1 is that this reflecting film consists of a transparent film substrate bearing light-reflecting spots in a pattern such that the amount of light reflected decreases as distance from the light-incident edge increases. Because more light is bounced back near the bright lamp edge and less is bounced back further away, the light ultimately passed through to the diffusing plate is evenly distributed across the panel.

In short: an edge-lit backlight where the traditional "hot spot" near the lamp is cured by a patterned partial-reflector (dot/spot film) whose reflectivity tapers with distance from the light source, plus a rear reflector and a diffusing front plate.

Dependent claims (brief)

• Claim 2 — adds light-reflecting edge-face layers on all edge faces except the light-incident face (covering the edges of the base plate, reflecting film, and diffusing plate).
• Claim 3 — those reflecting edge-face layers are inclined at an acute angle θ to the front surface (specification: preferably 75–88°; Example 1 uses ~82°).
• Claim 4 — the light source member is one or two tube-shaped lamps.
• Claim 5 — each tube lamp is wrapped in a flexible reflecting sheet with a slit facing the light-incident edge face.
• Claim 6 — the transparent light-transmitting layer predominates in volume within the base plate.
• Claim 7 — the intermediate layer has light-transmitting and light-diffusing properties intermediate between the transparent layer and the diffusing layer.

Litigation / CAFC check — specific result

I found no CAFC or district-court litigation docket naming US 4,729,068. This is unsurprising and consistent with the record: the patent's term lapsed on 2006-10-10 (Google's "anticipated expiration" entry), roughly 16 years before the requested 2026 docket check. The only IPR-context appearance I found was the patent being listed as search-art in a third party's exhibit in IPR2014-01359 (involving U.S. 7,914,196) — i.e., cited as prior art, not asserted.

Uncertainty note: I could not access a USPTO PatentCenter or PACER/CAFC docket directly through these searches, so I cannot rule out a fully dismissed or unindexed suit. But there is no indication in any searchable source that US 4,729,068 was ever asserted in litigation, and its expired status means no live 2026 CAFC appeal concerning it is plausible.

Related/background references cited in the patent

The specification situates the invention against: U.S. 4,059,916 (Copal); JP Kokai 61-55684; JP Utility Model Kokai 61-104,490; and its own assignee's earlier work U.S. 4,415,509 and U.S. 4,648,690 ("Light diffusing device," Mitsubishi Rayon — the apparent parent-concept patent). Polymer chemistry references cited include U.S. 3,804,925; 4,052,523; 4,173,600; and 4,508,875.

I'll search for litigation records involving US patent 4729068.

Let me refine my searches with more specific queries.

Let me search specifically for litigation and CAFC records.

Litigation Search: US Patent 4,729,068

Bottom line

I could not identify any known litigation (district court, ITC, or Federal Circuit/CAFC appeal) involving U.S. Patent No. 4,729,068. I want to be explicit that this is a negative finding based on the searches I was able to run, not a positive confirmation of "no litigation ever filed." Below I explain what I searched, what the identifiers in the results actually refer to, and the important caveats.

Patent identification (literal)

• US 4,729,068 A — "Light diffusing device"
• Inventor: Makoto Ohe
• Original assignee: Mitsubishi Rayon Co., Ltd. (3-19 Kyobashi 2-chome, Chuo-ku, Tokyo, Japan); current assignee listed as Mitsubishi Chemical Corp.
• Application: US 06/917,533, filed 1986-10-10
• Priority: GB 8623577 (1986-10-01)
• Granted / published: 1988-03-01
• Legal status: Expired – Lifetime; anticipated expiration 2006-10-10
• Family members: GB2196100B, DE3634493A1

Source (authoritative text): https://patents.google.com/patent/US4729068/en

Important disambiguation — the "'472" and "'068" hits in my searches are NOT this patent

My searches surfaced several documents that look superficially relevant but concern different patents. I am flagging these so they are not mistaken for litigation of 4,729,068:

1. "'472 Patent" in Blue Spike, LLC cases (E.D. Tex.) — In Blue Spike, LLC v. Lumidigm and Blue Spike v. ZK Technology (E.D. Tex., e.g., case gov.uscourts.txed.138874), the counterclaims seek declaratory judgment of invalidity/non-infringement of the "'472 Patent." That is a Blue Spike patent (a seven-digit patent), not US 4,729,068. These are unrelated to the Mitsubishi Rayon light-diffusing device.

2. "'068 patent" in Solas OLED cases — The PTAB petition citing "Solas OLED Ltd. v. LG Display / Apple / HP, Nos. 6:19-cv-00236, -00537, -00631 (W.D. Tex.)" refers to a later, still-in-force "'068 patent" (a 2005-filed patent, i.e., roughly US 8,290,068 / 7,7xx,1xx family) with "over seven years of remaining term." It is not the 1988 patent, which expired in 2006.

3. IPR2015-00361 and IPR2014-01359 (PTAB) — US 4,729,068 appears in these PTAB records only as a cited prior-art reference (e.g., "Exhibit 1007 – Ohe.pdf," and in search-string/prior-art lists alongside 4,418,378 / 4,779,166). Appearing as prior art is not litigation of the patent, and the Ohe patent here was not the patent under review (the IPRs concerned US 6,755,547 and US 7,914,196 respectively).

Why the absence of litigation is plausible

• The patent is a 1988-granted, expired patent (expired 2006) with a relatively narrow, product-specific claim set (7 claims) directed to an edge-lit light-diffusing device with a patterned light-reflecting film.
• It belongs to an era of Japanese-origin backlight art and is now frequently cited as prior art in modern backlight/light-guide IPRs (which matches what I found) rather than being asserted offensively.
• I could not, within my search budget, retrieve any Unified Patents litigation record, PACER docket, CAFC docket, or news item naming 4,729,068 as an asserted patent.

Caveats

• I could not fully verify against primary litigation databases. I was unable to pull the Unified Patents litigation case list (https://portal.unifiedpatents.com/litigation/caselist), PACER, or a CAFC docket search for this specific number before hitting my search limit. My negative finding should therefore be treated as preliminary.
• Verify independently via: Unified Patents portal (search "4729068"), PACER Docket Search / CourtListener (RECAP), and the CAFC docket (for any appeal naming 4,729,068), plus the USPTO Patent Center "Legal Events"/assignment record and any ITC Section 337 investigations.
• I did not auto-correct any number. Where a source used "'472" or "'068," I reported it as written and explained the mismatch.

Conclusion: No litigation involving US 4,729,068 is known to me based on these searches; the only database hits for this number are as prior art in PTAB proceedings (IPR2015-00361, IPR2014-01359), not as an asserted patent in any lawsuit.

I'll verify the structured ODP block against public sources before writing the analysis.

One more confirmation pass on whether this patent ever appeared in an AIA trial or post-grant proceeding under any caption.

Proceedings overview

There are no AIA trial proceedings on file for US 4,729,068 — zero IPRs, zero PGRs, zero CBM reviews — so there is no institution decision, no Final Written Decision, no settlement, and no Federal Circuit appeal to report. The USPTO Open Data Portal structured block returns an empty proceeding list, and independent web verification confirms it: the only PTAB artifacts naming "4729068" are prior-art search-string and exhibit references inside other parties' proceedings, not a challenge to this patent. Defensive posture for a defendant: this is a structurally unchallenged, long-expired patent — not a "hardened" one. Nothing has been canceled, nothing has been sustained by the Board, and all seven claims remain as printed in the 1988 grant, but the patent's term lapsed on 2006-10-10, roughly six years before the first IPR could be filed (2012-09-16). The Board has never had jurisdiction-relevant opportunity to touch it.

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No proceedings on file

Per the structured ODP block (canonical source for this analysis) and confirmed by search:

• Total AIA trial proceedings: 0
• Active: 0
• Claims invalidated: 0
• Claims sustained: 0
• Settled/terminated: 0
• Institution denied: 0

Why this is structural, not a strength signal. AIA post-grant trials became available on 2012-09-16. US 4,729,068 issued 1988-03-01, carried a priority date of 1986-10-01, and is listed by Google Patents as reaching anticipated expiration on 2006-10-10. Any AIA petition against this patent would have been filed against an already-expired patent — possible in the abstract, but commercially pointless, since there is no live infringement exposure to enjoin and no claim scope left to clear. The absence of IPRs here therefore tells you nothing about the claims' validity. It tells you the enforcement window closed first.

The closest thing this patent has to a PTAB footprint is confined to two cases about other patents, where 4,729,068 appears as cited art or as a search string:

IPR2014-01359 — petitioner v. patent owner of U.S. 7,914,196 (4,729,068 as cited art only)

• Type: Inter Partes Review (of U.S. 7,914,196, not of 4,729,068)
• Filed: petition documents dated 2014-08-21
• Status: Not a proceeding on 4,729,068. US 4,729,068 appears inside Exhibit 1002 — an examiner search-history document — where "4729068" appears as a bare patent number within EAST search strings such as ("1759782" "3752974" "4373282" "4418378" "4729068" "4779166" ...).PN.
• Defensive value: Zero precedential weight against 4,729,068. But it is useful evidence: it shows a sophisticated petitioner's counsel independently landed on 4,729,068 while surveying edge-lit backlight art, confirming it is well-known prior art in classification 362/31 and G02B6/0051.
• Source: https://www.docketalarm.com/cases/PTAB/IPR2014-01359/Inter_Partes_Review_of_U.S._Pat._7914196/docs/08-21-2014-Petitioner/Exhibit-1002-Ex_1002.pdf

IPR2015-00361 — petitioner v. patent owner of U.S. 6,755,547 (4,729,068 cited within cited art)

• Type: Inter Partes Review (of U.S. 6,755,547, not of 4,729,068)
• Filed: Exhibit 1016 dated 2014-12-04
• Status: Not a proceeding on 4,729,068. Exhibit 1016 ("Ohe.pdf") is EP 0 500 960 A1, an Ohe-family document whose specification expressly states that "Oe has reported a light diffusing device which comprises a light guide, a diffusing layer provided on the light guide through a layer having a middle characteristic … and a light regulation member for obtaining a uniform emitting light on the diffusing layer … and in United States Patent No. 4729068." That is a patent-family acknowledgment of 4,729,068 as background art — again, not a challenge.
• Defensive value: Useful confirmation from the same inventor lineage that 4,729,068's disclosure (intermediate layer + light-regulation member) was treated as known art by the mid-1990s. Supports an obviousness narrative against later patents, not against this one.
• Source: https://www.docketalarm.com/cases/PTAB/IPR2015-00361/Inter_Partes_Review_of_U.S._Pat._6755547/docs/12-04-2014-Petitioner/Exhibit-1016-Ohe.pdf

One verification gap I will not paper over: the ODP block covers AIA trials only. It does not, by itself, exclude a pre-AIA inter partes reexamination (available from 1999) or an ex parte reexamination filed during the 1999–2006 window. I found no reexamination certificate or reexamination proceeding associated with 4,729,068 in Google Patents' legal-status/prosecution record or in FreePatentsOnline, but I could not query the USPTO reexamination database directly, so I flag this as unverified rather than affirmatively absent.

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Strategic summary

Claim status across the patent — all seven claims are UNTESTED. Because no proceeding ever reached the merits, there is no Board-sanctioned cancellation and no Board-sanctioned survival. Claim 1 (the sole independent claim), and dependent claims 2–7, stand exactly as they were printed on 1988-03-01. There is no "surviving claim set" to point a defendant toward, because there is no narrowed claim set. Anyone who tells you this patent was "invalidated at the PTAB" is wrong; anyone who tells you it was "affirmed by the PTAB" is equally wrong. The Board has never ruled on it. (This is consistent with the prior section's finding of no district-court or CAFC litigation — the patent appears never to have been asserted.)

Estoppel landscape — the cleanest possible. There is no petitioner and therefore no § 315(e)(2) estoppel. No party is barred from raising any ground under §§ 102, 103, or 112, in any forum. Practically, this is moot for a defendant today: the patent expired 2006-10-10, which means (a) there is no ongoing infringing conduct to defend against, and (b) any damages theory would run into the § 286 six-year lookback — a suit filed in 2026 could at most reach conduct from 2020 onward, long after the patent ceased to exist. An expired patent cannot be infringed, and an IPR petition on it would be an expensive dead end (the Board can institute on expired patents, but no amendment is available and there is no practical upside).

Pattern signals. No repeat-petitioner pattern (no petitioners at all). No patent-owner PTAB-appeal history on this patent. No defensive aggregator in the chain — Unified Patents has no recorded challenge to 4,729,068, which is consistent with the expiration timing: Unified's backlight/display campaigns post-date 2006. The one pattern that does emerge is a prior-art pattern: 4,729,068 is cited by roughly 305 later publications according to the Google Patents "Cited By" record, was cited as background in EP 0 500 960 (same inventor lineage), and surfaces in examiner search histories for Solid State Opto's Parker light-emitting-panel family (e.g., IDS/search records for application 11/454,822). It is a keystone reference in edge-lit backlight art, which is the opposite of the profile of a patent worth attacking — it is the patent other people attack with.

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Recommended next steps

1. If you are a defendant facing a demand letter citing US 4,729,068: the first response is not an IPR — it is a standing/expiry letter. The asserted patent expired on 2006-10-10 (Google Patents, "Anticipated expiration"), more than a decade before any AIA trial existed. Cite 35 U.S.C. § 271 and § 286 and demand the plaintiff identify (a) the specific accused acts and (b) their dates. There is no valid infringement theory for post-2006 conduct, and pre-2006 conduct is § 286-time-barred.

2. If the demand nonetheless proceeds: the absence of PTAB activity is a signal against the plaintiff, not against you. A patent this widely cited in a commercially enormous field (LCD backlights) that was never once IPR'd, never once litigated, and never once reexamined — while sitting in the portfolio of a large, sophisticated corporate owner (Mitsubishi Rayon → Mitsubishi Chemical) — is consistent with it being either commercially unimportant or understood as narrow. Note that the "current assignee" listing (Mitsubishi Chemical Corp.) is flagged by Google Patents as possibly inaccurate; verify actual current ownership and any recorded assignments before engaging.

3. Do not file an IPR. There is no live claim scope to clear, § 315(b)'s one-year bar is irrelevant, and no § 315(e)(2) estoppel benefit is achievable on an expired patent. Filing would burn fees with no defensive return.

4. If your goal is the opposite — invalidating someone else's later backlight patent — then 4,729,068 is a valuable prior-art weapon, not a target. Its 1986-10-01 priority date, its intermediate-layer + patterned-reflector-film disclosure, and its appearance in both the EP 0 500 960 background discussion and examiner search histories give you a documented, publicly acknowledged § 102(b) reference for art in classification 362/31 and G02B6/0051. The family (GB 2196100B, DE 3634493A1) gives you foreign counterparts for a multi-jurisdiction attack.

5. Verification step I could not complete: confirm the absence of any pre-AIA reexamination via the USPTO Patent Public Search "reexamination" record and the Image File Wrapper for US 06/917,533 at https://patents.google.com/patent/US4729068/en. If a certificate exists, it would be the only thing that could have altered the claim text. Nothing in the sources I checked indicates one does.

I'll search for assignment records and ownership history for this patent.

Let me look for the corporate history and any recorded reassignments.

Let me try to pin down the recorded reel/frame for the 1987 assignment and any later name-change recording.

Inventors

No unusual inventor pattern is present. There is a single inventor, he was a Mitsubishi Rayon employee, and his rights were assigned to that employer rather than away from it (see timeline). There is no multi-inventor team dispersing within 12 months of filing, and no evidence any inventor left the assignee — the "departing-inventor / fire-sale precursor" pattern is not present.

Original assignee

Mitsubishi Rayon Company, Ltd. (later Mitsubishi Rayon Co., Ltd.), 3-19 Kyobashi 2-chome, Chuo-ku, Tokyo, Japan — the assignee named on the issued patent (front page) and confirmed by the recorded 1987 assignment.

• Line of business: A large Japanese chemical/materials manufacturer (founded 1950 as a rayon producer) that became a leading producer of acrylic resins and optical sheet — i.e., MMA/acrylic, carbon fiber, and performance materials. It is a classic operating company, not a holding vehicle.
• Product embodying the claims: Yes — the device is an edge-lit backlight panel built from Mitsubishi Rayon's own acrylic materials. The specification's Example 1 uses the assignee's own commercial products, "Hipet" acrylic molding resin and "Acrylite #432" milk-white diffusing plate (both registered trademarks of Mitsubishi Rayon Co.), demonstrating that the claimed article was manufactured from the assignee's catalogued materials.
• Current status: Operating (as part of a larger group), not dissolved. Mitsubishi Chemical Holdings Corporation acquired Mitsubishi Rayon around April 2010. On 2017-04-01, Mitsubishi Rayon Co., Ltd. absorbed Mitsubishi Chemical Corporation (old) and Mitsubishi Plastics, Inc., and simultaneously changed its name to Mitsubishi Chemical Corporation (new) — the surviving legal entity is Mitsubishi Rayon renamed, not a new corporation. This is confirmed by Mitsubishi Chemical's own press releases and by the Japanese CDS Determinations Committee decision of 2018-03-26 (succession date 1 April 2017).

Assignment timeline

The Google Patents legal-events ("reassignment") record for US 4,729,068 lists one recorded assignment, and I found no others:

• Executed: not exposed in the retrieved record / recorded 1987-11-24 — Reel/Frame not retrievable from the sources I could load
  • Conveyance: Assignment of assignors' interest ("ASSIGNMENT OF ASSIGNORS INTEREST")
  • Assignor: Ohe, Makoto
  • Assignee: Mitsubishi Rayon Company, Ltd., 3-19 Kyobashi 2-chome, Chuo-ku, Tokyo, Japan
  • Correspondent: Not determinable from available sources. I could not retrieve the recording correspondent (the filing attorney/agent of record) for this 1987 entry; I am flagging this as an unresolved data gap rather than guessing. I therefore cannot run the "repeat correspondent" cross-check the task asks for.
  • Context: Ordinary employee-inventor → employer assignment executed in connection with filing (recorded ~13 months after the 1986-10-10 US filing). Not a sale, fire-sale, or securitization.

Possible later recording — unresolved. Separately, I found evidence that Mitsubishi Rayon's 2017 corporate name change was recorded at the USPTO in batch "corporate name change" filings (e.g., Reel/Frame 042886/0294, recorded 2017-06-19; and a 2017-07-20 batch carrying Reel 043265/0730 and Reel 043266/0713–0734, all styled as Mitsubishi Rayon Co., Ltd. → Mitsubishi Chemical Corporation, effective 2017-04-01). However, US 4,729,068 does not appear in these records, and the Google Patents legal-events feed for this patent shows only the 1987 assignment. This is consistent with the patent having expired on 2006-10-10, before the 2017 name-change batch — expired patents are typically not carried into such recordings. I could not load the Assignment Center / assignment.uspto.gov detail page directly to confirm definitively, so treat the "no 2017 recording" point as likely but unverified.

If the Assignment Center in fact shows no records beyond the 1987 entry, that is itself the finding: the patent never left the Mitsubishi corporate family; the original assignee (and its renamed successor) still owns it.

Timeline diagram

timeline
    title Ownership of US 4729068
    1986 : Application filed by Mitsubishi Rayon
         : Inventor Ohe is a Rayon employee
    1987 : Ohe assigns rights to Mitsubishi Rayon
    1988 : Patent issued Mar 1
    2006 : Patent expires Oct 10
    2010 : Mitsubishi Chemical Holdings acquires Rayon
    2017 : Rayon renamed Mitsubishi Chemical

NPE / troll-pattern signals

1. Shell-entity transfer — Not present. The only recorded transfer is Ohe → Mitsubishi Rayon, an operating acrylic/chemicals manufacturer. No "IP / Holdings / Licensing / Ventures" successor, no registered-agent address, no single-purpose LLC anywhere in the chain.

2. Known asserter in the chain — Not present. Mitsubishi Rayon / Mitsubishi Chemical is not on any Acacia, Marathon, IV, Wi-LAN, Conversant, Pendrell, Round Rock, Spangenberg, or similar list I know of; it is a manufacturing conglomerate. The patent's only appearance in case records is as cited prior art, not as an asserted patent (e.g., cited in PTAB IPR2014-01359 concerning US 7,914,196 and IPR2015-00363 concerning US 7,404,660, where it appears in petitioner exhibit search histories alongside US 4,418,378 and US 4,779,166).

3. Repeat correspondent across the chain — Unclear / not assessable. There is only one assignment in the chain, and its recording correspondent could not be retrieved. With a chain of one, the recurrence test cannot be run.

4. Cascading transfers — Not present. One transfer, in 1987, with no subsequent chained LLC-to-LLC conveyances.

5. Pre-litigation transfer — Not present. No infringement suit naming US 4,729,068 was identified in the prior litigation pass, and there is no assignment within 6 months before any such suit.

6. Bankruptcy fire-sale — Not present. No Chapter 7/11 sale; the original assignee's successor remains an ongoing operating company.

7. Privateering — Not present. No transfer to a third-party assertion vehicle; ownership stayed inside the Mitsubishi group through the 2017 merger/name change.

8. Defensive aggregator (anti-NPE) — Not present. The chain does not terminate at RPX, AST, LOT Network, Unified Patents, or OIN.

Verdict

Insufficient data (only the original assignment).

The entire recorded chain is a single, ordinary employee-inventor assignment — Ohe, Makoto → Mitsubishi Rayon Company, Ltd., recorded 1987-11-24 — on a patent that issued 1988-03-01 and expired 2006-10-10. Ownership never left the Mitsubishi corporate family (Mitsubishi Rayon was acquired by Mitsubishi Chemical Holdings ~2010 and renamed Mitsubishi Chemical Corporation on 2017-04-01), so there is no shell entity, no known asserter, no cascading LLC transfers, and no pre-suit transfer to score. I found no NPE-pattern signals, but because I could not load the Assignment Center detail page directly (and could not retrieve the 1987 recording's reel/frame or correspondent), I decline to upgrade this to a positive "operating-company" finding — the honest call is insufficient data, with all eight NPE indicators assessed as not present on the evidence available.

Verify independently at: https://assignmentcenter.uspto.gov/ (and the legacy index at https://assignment.uspto.gov/patent/index.html), searching patent number 4729068, and cross-check Reels 042886/0294, 043265/0730, and 043266/0713–0734 to confirm whether the 2017 Mitsubishi Rayon → Mitsubishi Chemical name-change batch touches this patent.

I'll verify the citation list and gather details on each reference. Let me run targeted searches.

Now the two Mitsubishi Rayon references and the specification-discussed art.

Prior-Art Analysis for US 4,729,068 ("Light diffusing device")

Method note / limitation: I could not execute a live USPTO PatentCenter query for this number (tool budget exhausted before a direct USPTO-database pull). What follows is built from the authoritative full text of the patent supplied to me (Google Patents' OCR of the printed US front page and specification, source https://patents.google.com/patent/US4729068/en), corroborated by FreePatentsOnline (https://www.freepatentsonline.com/[4729068](/patent/4729068).html) and by independent record pulls for individual references. I did not auto-correct any patent number, and where a source's identifier conflicts with what the patent itself says I flag it rather than resolving it silently (see §7).

Two front-page tables on the patent are relevant and are identical to each other, so there is no internal conflict:

• "Patent Citations (6)" / "Citations (6)" — the examiner-cited US patents.
• "Family Cites Families (7)" — references carried in the family/related record.

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1. Target patent (identity confirmed)

Critical dates for §102. Pre-AIA §102 governs (filed 1986). The relevant critical date is the invention date, at latest the GB priority date of 1986-10-01; the constructive reduction date is the 1986-10-10 US filing. A reference published before 1985-10-10 is a §102(b) statutory bar; anything published between 1985-10-10 and the invention date can only be §102(a) art.

Decomposition of claim 1 (used throughout §4):

Dependent claims add: 2 edge-face reflectors (all faces but the incident one); 3 those edge reflectors inclined at acute angle θ; 4 one or two tube lamps; 5 each tube wrapped in a slit flexible reflector; 6 E2a predominates in volume; 7 E2c has intermediate transmitting/diffusing properties.

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2. The complete citation set on US 4,729,068

Table A — Examiner-cited US patents (front page, "Patent Citations (6)")

Table B — Additional "family cited" documents (7)

Table C — References named in the specification body but absent from the citation tables

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3. Reference-by-reference §102 analysis

General rule applied: a reference anticipates only if it discloses every element of the claim, arranged as claimed. Every dependent claim carries all of claim 1, so no dependent claim can be anticipated by a reference that does not meet claim 1.

A1 — US 2,358,203 (Best), pub. 1944-09-12 — §102(b)

• §102 status: Printed US patent published >40 years before the critical date → §102(b) statutory bar art as to all claims.
• Disclosure mapped to claim 1: At most the preamble concept of E1 + a light-transmissive viewing panel (E3-type). Its title and classification (illuminating/viewing device) place it in the general field of illuminated viewing panels.
• Claims potentially anticipated: None. There is no disclosure of E2a–E2d (the layered edge-lit base plate with intermediate layer and rear reflector), of E4 (a non-contacting interposed film), or of E5 (graded reflecting spots). It cannot anticipate claim 1 or any dependent claim.
• Value: background/general-field art only.

A2 — US 3,131,496 (Grub / Schropp), pub. 1964-05-05 — §102(b)

• §102 status: §102(b) as to all claims.
• Disclosure: A display board having a transparent optical-grade PMMA carrier plate (E2a) and a tubular electric lamp positioned along an edge face of that plate (E1). Beyond that, the disclosure is directed to luminous sign formation, insertable/changeable information, and confidentiality of displayed information — not to light diffusion management.
• Claims potentially anticipated: None in full. It discloses the E1 + E2a sub-combination only. It does not disclose E2b (diffusing layer), E2c (intermediate layer), E2d (rear reflecting layer), E3, E4 or E5. It is, however, the strongest §102(b) reference for the "edge-lit transparent plate with a tube lamp at the edge face" idea and is correspondingly relevant to claim 4 (one or two tube-shaped lamps) — but only as an element, not as a claim in full.
• Value: High for element E2a/E1 and claim 4 context; not anticipatory.

A3 — US 3,586,851 (Rudolph), pub. 1971-06-22 — §102(b)

• §102 status: §102(b) as to all claims.
• Disclosure: Heat management in an illumination train — dichroic reflective coatings on a transparent substrate (242/244, 251/253), liquid cooling, polarizer, cooled "light bar." The only surface contact with the present claims is the abstract idea of a reflective coating carried on a transparent substrate (tangential to E2d/E5).
• Claims potentially anticipated: None. No edge-incident transparent layer, no diffusing layer, no intermediate layer, no diffusing plate, no patterned reflecting film. Very likely cited for the general notion of coated reflective substrates / lamp-and-reflector assemblies.
• Value: Peripheral.

A4 — US 4,053,206 (Personal Communications, Inc.), pub. 1977-10-11 — §102(b)

• §102 status: §102(b) as to all claims.
• Disclosure: The lensfiche system's sheet-lighting elements. Claim 5 of that patent recites a transparent sheet (index N2) with lower-index coatings, light-conducting channels carrying ~45° reflectors that direct light normal to the sheet, a second opaque coating apertured at each reflector and adjacent each reflector, and a parallel light-conducting sheet. This is a patterned arrangement on a transparent substrate for controlling where light exits a sheet.
• Claims potentially anticipated: None in full. It is the closest of the pre-1980 references to the structure of E5 (reflecting elements arrayed on a transparent substrate to redistribute light) and to E4 (a discrete transparent-sheet element interposed in a light path). But it discloses no distance-dependent (graded) reflectivity relative to a light-incident edge face, no light-diffusing layer, no intermediate layer, no rear reflector layer, and no superimposed diffusing plate. It therefore cannot anticipate claim 1 or any dependent claim.
• Value: Moderate — relevant to the inventive core (E4/E5) as structure, but the graded distribution that defines claim 1 is absent.

A5 — US 4,415,509 (Mitsubishi Rayon / Toyooka), pub. 1983-11-15 — §102(b)

• §102 status: §102(b) as to all claims.
• Disclosure: Integrated laminate of a light-diffusing-agent-containing acrylic film on an acrylic resin plate, formed by casting monomer/partially polymerized syrup against the film so that the film is partially dissolved and/or swollen and becomes one body with the polymerizing plate. This is, on its face, the same base-plate construction and method the '068 specification expressly relies on ("The above-mentioned method is disclosed in U.S. Pat. No. 4,415,509"). The dissolved/swollen interfacial region corresponds to E2c (intermediate layer), the film to E2b, and the polymerized plate to E2a.
• Claims potentially anticipated: None in full. The '509 patent discloses a panel/laminate and its production process, not an edge-lit illumination device: it lacks E1, E2d (rear reflecting surface layer), E3, E4 and E5, and its disclosure does not require an edge incident face. It anticipates at most the material/laminate sub-combination of E2a–E2c, not any claim of the '068 patent.
• Value: High for the base-plate sub-combination and for §103 combination purposes; the patentee's own specification admits it as known.

A6 — US 4,648,690 (Mitsubishi Rayon), filed 1984-08-27, pub. 1987-03-10 — §102(e) candidate only

• §102 status — this is the analytically important one. Its publication date (1987-03-10) post-dates both the 1986-10-01 priority date and the 1986-10-10 US filing. It therefore cannot be §102(a) or §102(b) art. Its only route into §102 is pre-AIA §102(e) — "a patent granted on an application for patent by another filed in the United States before the invention thereof by the applicant" — on the strength of its 1984-08-27 filing date, assuming a different inventive entity than Ohe. (If the examiner cited it, that is the only theory available, and it is confirmed by the dates.)
• Disclosure (per the record I have): Same-assignee "Light diffusing device." On the specification's own account of the background, the closest admitted art (JP Kokai 61-55684, and its addition per JP UM Kokai 61-104,490) discloses a base plate with a transparent layer, a light-diffusing layer, an intermediate layer, a rear reflecting surface layer, and an edge incident face, plus a light-diffusing plate over it — i.e. E1, E2a–E2d and E3. The '690 patent is the US front-page citation whose subject matter most nearly matches that description, and it is plausibly the US counterpart of that admitted background.
• Claims potentially anticipated: If '690 discloses only the base plate + superimposed diffusing plate, it fails to disclose E4 and E5 — the interposed, non-contacting light-reflecting film made of a transparent substrate bearing spots whose reflectivity decreases with distance from the light-incident edge. Under that reading, no claim is anticipated, and '690 functions as the closest §102(e)/§103 reference against which the added film was allowed. I cannot confirm its full disclosure — I was unable to retrieve its specification text — so I flag this as the single most important item to verify (§8).
• Value: Highest-ranked reference in the set (whether under §102(e) or §103).

Secondary references (Tables B and C)

• B2/US 4,059,916 (Copal), pub. 1977-11-29 — §102(b). Discloses the matted (hairline-roughened) rear surface + rear reflecting layer + thickness tapered away from the light-source edge. It discloses E1, E2a, a rear reflecting layer (E2d-type) and a thickness taper, and is the reference the patent distinguishes as unduly costly. It does not disclose the intermediate layer (E2c) or the graded reflecting film (E4/E5). No claim anticipated.
• JP Kokai 61-55684 (1986) — §102(a) printed publication (published <1 year before the US filing, so not a §102(b) bar). Discloses the E1 + E2a–E2d base plate with edge incident face and rear reflector. No claim anticipated (no E4/E5; and disclosure is of the base plate alone).
• JP Utility Model Kokai 61-104,490 (1986) — §102(a). Discloses superimposing a light-diffusing plate (E3) on that base plate. No claim anticipated (no E4/E5).
• B1, B3, B6 and the missing US 4,508,875 — §102(b). These are polymer-chemistry references (multi-stage/multi-layer acrylic polymers) cited for the composition of the matrix resin of the light-diffusing layer (E2b) and the intermediate layer (E2c). They contain nothing relevant to the claiming structure. No claim anticipated.
• B4/B5/B7 — see §7; the underlying documents (US 4,052,523, JP 55-684, JP 61-104490) are cited for polymer chemistry or for the light-diffusing plate placement, and anticipate no claim on the record available.

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4. Direct answer: which claims each reference could anticipate under §102

Conclusion of the §102 sweep: On the record available, no cited reference anticipates any of claims 1–7. What has to be found in one reference to anticipate claim 1 is the combination of (i) an edge-lit layered base plate with an intermediate layer and rear reflector, (ii) a superimposed diffusing plate, and (iii) an interposed, non-contacting transparent film bearing light-reflecting spots whose reflectivity decreases with distance from the light-incident edge. The cited art supplies, at most, elements (i) and (ii) — never (iii). That unreached limitation (E5) is also what the specification stresses as the reason for the tapering is needed ("it is necessary to reflect light irradiated from a portion of the base plate close to the light incident edge face toward the base plate… the smaller the distance from the light incident edge face, the larger the amount of light to be reflected"), and what the later art in the "Cited By" list picked up (e.g., US 5,283,673, Meitaku Shisutemu, "Surface luminous source panel with areas having different reflector speck densities").

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5. Ranking of the most relevant prior art

1. US 4,648,690 (Mitsubishi Rayon, filed 1984-08-27, pub. 1987-03-10) — closest overall; §102(e) candidate; the reference to obtain and read first.
2. US 4,415,509 (Mitsubishi Rayon, 1983-11-15) — the base-plate laminate and its dissolution/swelling bond; expressly incorporated by the specification.
3. JP Kokai 61-55684 and JP Utility Model Kokai 61-104,490 (both 1986) — the admitted closest concepts the invention improves upon.
4. US 3,131,496 — edge-lit PMMA plate with a tube lamp at the edge face (E1/E2a; claim 4 context).
5. US 4,053,206 — patterned light-redirecting elements on a transparent sheet (structural analogue of E4/E5, without the graded distance dependence).
6. US 4,059,916 (Copal) — matted rear surface + rear reflector + taper.
7. US 2,358,203 and US 3,586,851 — general-field/coated-reflector background only.
8. Polymer-chemistry references (US 3,804,925; 4,052,523; 4,173,600; 4,508,875; CA 1,188,022) — composition-of-matter support, no structural relevance.

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6. Data-integrity flags (identifiers left as found)

1. US 4,648,690 publication date vs. the '068 filing date. Google lists '690 as published 1987-03-10, i.e. after the '068 US filing of 1986-10-10. Any examiner reliance on it must therefore be §102(e) (filing 1984-08-27), not §102(a)/(b). This is a real constraint, not a typo.
2. "JPS55684A / Power unit for aural amplifier / Toshiba / 1980-01-07" (B5) vs. "JP Kokai 61-55684." These are different Japanese identifiers (JP 55-684 vs. JP 61-55684). The specification text cites 61-55684. The Google citation-table row appears mis-mapped. I have not merged them.
3. "US 4,052,523 — Composite sandwich lattice structure — NASA" (B4). The specification cites US 4,052,523 as one of the multi-stage-polymerized alkyl methacrylate references. A NASA composite sandwich lattice structure does not match that description; treat this citation-table row with suspicion pending a check of the printed front page.
4. "JPS61104490A / Bipolar RAM / Hitachi Micro Comput Eng" (B7). The specification cites JP Utility Model Kokai 61-104,490 for a light diffusing plate over a base plate — not a bipolar RAM. Again a likely mis-mapping.
5. US 4,508,875 is named in the specification's description ("U.S. Pat. Nos. 3,804,925, 4,052,523, 4,173,600 and 4,508,875") but does not appear in either Google citation table. Conversely, US 4,648,690 appears on the front page but is not discussed in the specification body — so the earlier-generated summary's statement that the specification "situates the invention against … U.S. 4,648,690" overstates the record; '690 is a front-page citation only. (Flagging per the cross-reference instruction.)
6. US 3,131,496 dates. Google shows 1958-05-31 (the German priority); FPO shows the US filing as 1959-06-01 (appl. US 817,417,59), publication 1964-05-05. Both are accurate for their respective fields.
7. Google's two front-page citation tables ("Patent Citations (6)" and "Citations (6)") are identical — no conflict.

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7. What I could not verify (and how to close it)

• Full disclosure of US 4,648,690. This governs whether it is merely the closest §103 reference or a genuine §102(e) anticipation of claim 1. Read it at https://patents.google.com/patent/US4648690/en or https://patentimages.storage.googleapis.com/.../US4648690.pdf.
• Exact publication dates of JP Kokai 61-55684 and JP UM Kokai 61-104,490. These determine whether they are §102(a) or §102(b) art (the one-year bar date is 1985-10-10). A Showa-61 (1986) publication is inside the year and therefore §102(a) only.
• The printed front page itself (the authoritative "References Cited" list including any examiner initials and the "Other Documents" field): https://patents.google.com/patent/US4729068/en and USPTO PatentCenter for application 06/917,533. Google's OCR is the source I used and it contains at least the four mis-mapping anomalies in §6.
• I did not identify any litigation or PTAB proceeding in which US 4,729,068 was the patent under review; the only PTAB appearances I found earlier were as cited prior art (Exhibit 1007 "Ohe.pdf" in IPR2014-01359; and in the IPR2015-00361 record). That finding is unaffected by this citation analysis.

I'll ground this obviousness analysis in the actual prior-art references listed on the patent page before arguing the § 103 combinations.

Good grounding on the Copal, Mitsubishi Rayon and Rudolph references. Let me pin down the two Japanese references the specification relies on, plus early "graded dot/patterned reflector" art.

Obviousness Analysis — US 4,729,068 ("Light diffusing device") under 35 U.S.C. § 103

Note on framework. The application was filed 1986‑10‑10 with a 1986‑10‑01 GB priority (GB 8623577), so pre‑AIA §§ 102/103 apply and the critical date for the hypothetical PHOSITA is 1 October 1986. I interpret all identifiers literally and flag, rather than silently correct, every mismatch I found.

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1. The prior-art universe actually on this page

Two mismatches I will not auto-correct (flagging explicitly). Google's "Family Cites Families" table maps the specification's JP Kokai 61‑55684 to JPS55684A – Toshiba – "Power unit for aural amplifier", and the specification's JP UM Kokai 61‑104,490 to JPS61104490A – Hitachi – "Bipolar RAM". Those are unrelated documents; the JP Shōwa‑61 publications the '068 specification actually relies on were not retrieved within my search budget. Do not treat the Toshiba/Hitachi entries as the asserted art.

PHOSITA definition I assume: a person with a bachelor's degree in optics, mechanical engineering, or polymer materials, plus 2–3 years of experience designing edge‑lit backlights/light guides, who is familiar with (i) TIR light‑guide physics, (ii) methacrylate lamination, and (iii) the commercial literature on backlights for LCDs and advertising panels.

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2. Claim 1 — element map

So the case turns on one loaded limitation: the graded, discrete‑spot partial reflector in the air gap. Everything else is squarely in the admitted/statutory art.

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3. Grounds of rejection

Ground 1 (primary): JP 61‑55684 + JP UM 61‑104,490 + US 4,059,916 → claim 1

• 56,684 gives the whole base plate (A)(a)–(d) — the specification concedes this ("the above‑described light diffusing device is significantly advantageous in cost").
• 61‑104,490 adds the superimposed light‑diffusing plate (B) to improve brightness uniformity.
• 4,059,916 supplies the missing concept (C): an edge‑lit panel in which the reflective/transmissive character of a surface is deliberately made a function of distance from the lamp (directionally roughened rear surface plus a bevelled far edge) so that light is emitted "uniformly over the entire area."

Motivation to combine (KSR, 550 U.S. 398): all three address the identical problem — uniform surface luminance from an edge‑illuminated panel — and the '068 specification itself supplies the market pull ("recent demand for a display on a large screen having a size of 10 to 14 inches … an increased demand for an even further increased uniformity"). A PHOSITA seeking more uniform output from the 61‑55684 + 61‑104,490 device would look to the leading edge‑lit teaching ('916) for the only known way to flatten the fall‑off: make the reflector progressively less reflective away from the lamp. Placing the graded reflector as a film in the gap already provided by 61‑104,490/'067 is an "arrangement of old elements," each performing its known function; the result (less light reflected near the bright lamp edge, more light passed far away) is the predictable, indeed arithmetically necessary, consequence. No new principle of operation is invoked.

Extra, unusually strong motivation from the '068 text itself: the specification criticizes the '916 approach precisely because "the production of the light diffusing plate can be attained only by very fine, delicate and precise work on a surface of a transparent light transmitting plate, and this work causes an extreme increase in the production cost." That is an express statement of a design incentive to substitute a cheaper, mass‑producible patterned film (vapor‑deposit + etch / photoresist) for a mechanically roughened graded surface — the classic "known alternative with a known cost advantage" rationale.

Ground 2 (alternative): JP 61‑55684 + JP UM 61‑104,490 + US 4,053,206 (+ 4,059,916) → claim 1

If an examiner prefers a reference showing discrete spots on a transparent sheet rather than a graded roughened surface, US 4,053,206 supplies the "light reflecting spots formed on a transparent film substrate" structure: reflecting elements 312/312′ are positioned "at the edges of squares 100 mils on a side" on a methyl‑methacrylate light sheet. Motivation: substituting a discrete, printed/deposited dot array for a continuous roughened surface is a mere change in the form of the same known light‑redirecting element, chosen for manufacturability and pattern controllability — and the '068 specification itself concedes the '916 roughened approach was too expensive. Combining '206's spot array with '916's distance‑gradation teaching yields claim 1(C).

Ground 3 (fallback if the JP publications are held not to be prior art)

If JP 61‑55684/61‑104,490 are disqualified (see §5), the same result is reached with US 4,059,916 + US 4,415,509 + US 4,648,690: '916 for the edge‑lit architecture, plural lamps, edge reflectors and graded reflector; '509 for the integrally laminated transparent plate/diffusing layer with a swollen interfacial zone (the intermediate layer); '690 for the inclined acute‑angle edge faces with irregular reflecting layers.

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4. Dependent claims

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5. Counter‑arguments and where the rejection is vulnerable

1. No reference discloses the exact (C) structure. Grounds 1–2 depend on combining '916's graded surface teaching (or '206's spot array) with a film interposed in an air gap. A patentee will argue hindsight — that '916's roughness gradient is a surface property of the light guide, not a separate transmissive film. Rebuttal: KSR permits combination where the references address the same problem with predictable results, and '206 supplies the discrete‑spot‑on‑film structure.

2. "Without being in contact" (the air gap). This is presented as critical (thin air layers), but the same gap/dispacing idea appears in the sibling US 4,729,067 ("light diffusing plate arranged on and in the vicinity of the light diffusing layer but not in contact with the light diffusing layer"). If '067 shares an earlier effective date it is §102(e) art for this element; I could not verify its filing date (its application number sits adjacent to 06/917,533, suggesting same‑day filing, in which case it is not prior art). Flagging this as unresolved.

3. Objective indicia. A patentee would point to long‑felt need and rapid industry adoption of dot‑pattern light guides (visible in the post‑dating Cited‑By list — e.g., US 5,283,673, Meitaku, "areas having different reflector speck densities," 1989). But post‑filing art cannot be used as prior art, and any secondary‑considerations argument needs a nexus; more damagingly, the patent's own Example 2 report is non‑uniform — 6,420 / 16,000 / 21,300 / 23,000 / 23,600 / 23,600 / 22,800 / 19,200 / 11,800 / 4,460 cd/m² across ten sections (a bell distribution, ~5× edge‑to‑center variation). That data undercuts any argument that the claimed configuration produced unexpectedly uniform output.

4. Material/dimension claims. Thicknesses (0.3–20 mm layer; 0.05–1 mm diffusing layer; 0.01–0.2 mm intermediate layer; 25–125 µm substrate; x = 30–40 mm; r = 30–50 %; θ = 75–88°) appear only in the specification, not in the claims (claim 3 recites merely "acute angle"), so no range‑criticality issue arises.

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6. Explicit uncertainties

• Publication dates of JP 61‑55684 and JP UM 61‑104,490 were not verified. Both are Shōwa‑61 (1986) documents. If either published after 1986‑10‑01, or if it is the same applicant's own work within the one‑year grace period, it may fail pre‑AIA §102(a) ("by others") and §102(b) (〉1 year). The secure statutory route is US 4,059,916, US 4,053,206 and US 4,415,509 (all §102(b)) plus US 4,648,690 (§102(e), subject to the "by another" requirement); the JP documents remain usable at minimum as admissions in the '068 specification, which the Federal Circuit treats as prior art admissions.
• I could not retrieve the text or exact dates of JP 61‑55684 / JP UM 61‑104,490 within my search budget, and I did not retrieve US 4,648,690's US filing date or inventive entity to test the §102(e) "by another" requirement.
• Google's automated family‑citation mapping of those two JP numbers is demonstrably wrong (Toshiba "Power unit for aural amplifier"; Hitachi "Bipolar RAM"); I report them as found and do not rely on them.

Bottom line. Claims 1, 2, 3, 4, 6 and 7 are, in my assessment, more likely than not obvious under pre‑AIA §103 over JP 61‑55684 + JP UM 61‑104,490 in view of US 4,059,916, with US 4,053,206, US 4,648,690 and US 4,415,509 as supporting or alternative references; claims 6 and 7 are arguably anticipated on the applicant's own characterization of JP 61‑55684. Claim 5 (slit‑wrapped flexible lamp reflector) is the only claim for which I found no squarely on‑point disclosure and which could plausibly survive.