US 7450090

I'll search for the patent and any 2026 CAFC docket activity.

US Patent 7,450,090 — Verified Summary

Important scope note up front: I found no 2026 CAFC docket activity involving U.S. Patent 7,450,090, and no 2026 litigation asserting it. I also want to flag a near-miss that should not be confused with this patent: the Hitachi Plasma Patent Licensing v. LG Electronics case (E.D. Tex. 2:07-cv-00155-CE) refers to "the '590 patent," but that is a different patent titled "Surface Discharge Plasma Display Panel." That is not US 7,450,090. I did not find 7,450,090 asserted in any of the 2026 Maxell campaigns (LG, Samsung, Hisense, or ITC Inv. No. 337-TA-1516), all of which assert other numbers ('646, '408, '760, '692, '211, '935).

Bibliographic data (verified against Justia and Google Patents)

Prosecution chain (continuations): 11/396,611 is a continuation of Ser. No. 10/961,029 (filed Oct. 12, 2004, now US 7,071,901), which is a continuation of Ser. No. 10/222,583 (filed Aug. 19, 2002, now US 6,822,627, issued Nov. 23, 2004). It later spawned continuation 12/120,807 (US 2008/0218439 A1), which was abandoned.

Abstract (as issued)

A plasma display panel and imaging device realizing high luminous efficiency, long lifetime, and stable driving. The PDP uses a discharge-gas mixture containing at least Xe, Ne and He. Xe proportion is 2%–20%, He proportion is 15%–50%, the He proportion is greater than the Xe proportion, and total pressure is 400–550 Torr. A width of a voltage pulse applied to an address electrode is 2 μs or less.

Independent claims — plain language

There are four independent claims: 1, 20, 39, and 59. All four share the same core numerical limitations (Xe 2–20%; He 15–50%; He > Xe; address pulse width ≤ 2 μs) and differ only in structural framing:

• Claim 1 — A PDP with a discharge space, discharge electrodes including an addressing electrode, and a circuit that applies a voltage pulse to that electrode to produce a write-discharge. The gas mixture "contain[s] at least" Xe, Ne and He. Notably, claim 1 does not recite the 400–550 Torr total-pressure limitation.

• Claim 20 — Narrower structural framing: a pair of sustaining discharge electrodes, an address electrode facing the pair, and a discharge space between them; same gas/pulse limitations. Again, no total-pressure recitation.

• Claim 39 — Same as claim 1, but the gas is a mixture "consisting essentially of" Xe, Ne and He (closed-ended as to additional active gases; impurities permitted per the specification).

• Claim 59 — Same as claim 20, but again "consisting essentially of" Xe, Ne and He.

Where the pressure limitation lives: 400–550 Torr appears only in dependent claims 9, 28, 46, and 66. So the independent claims as issued cover He/Xe proportions and pulse width, but not the total pressure — the pressure range must be pulled in via a dependent claim. This is worth noting if you are analyzing scope.

Other dependents worth noting: written-description limits on write-discharge voltage tied to cost (≤70 V in claims 12/31/50/70; ≤65 V in 14/33/52/72; ≤60 V in 16/35/54/74; ≤55 V in 18/37/56/76), and "essentially rectangular-shape pulse in a write-discharge period" (claims 10/29/48/68). Roughly half the claim set (claims 3, 5, 7, 8, 11, 13, 15, 17, 19, and the parallel sets) is directed to an imaging device comprising the PDP plus a driving circuit including at least a control circuit.

Technical basis in the specification

• He addition is credited with increasing cascade transitions into excited Xe states that generate UV (citing Uemura et al., Proceedings of IDW '00, pp. 639–642).
• The He effect is said to require He > Xe, which is why that inequality is a claim limitation.
• He above 50% (experiments at 60%) sharply degrades brightness maintenance ratio (lifetime); Xe above 20% forces sustained discharge voltage up steeply (FIG. 8).
• Total pressure 400–550 Torr is the stated optimum (FIG. 11); 600 Torr is considered too close to atmospheric for high-altitude use, and ≤350 Torr degrades both efficiency and lifetime.
• The ≤2 μs address-pulse limit addresses write-discharge delay/flicker caused by rapid loss of priming particles at higher Xe, and enables a shorter write period (higher definition) and lower write voltage (lower cost).

Uncertainty / caveats

• I could not verify any CAFC 2026 docket, appeal, or IPR/PTAB proceeding naming US 7,450,090 specifically. Given the patent's pre-2022 expiration and the fact that Maxell's 2026 TV/smart-device campaigns assert unrelated later patents, a 2026 appeal on this patent is unlikely — but I cannot prove a negative from the searches performed.
• Assignee history after 2008 is drawn from Google Patents' reassignment record and is presented as an assumption, not a legal conclusion (consistent with Google's own disclaimer).
• The "anticipated expiration" date of Aug. 19, 2022 (rather than 20 years from the 2002-05-27 priority date) reflects the 20-year term running from the parent application's Aug. 19, 2002 filing date. I have not independently audited whether any PTA or terminal disclaimer affected the term.

I'll search for litigation involving US patent 7,450,090.

Initial searches returned unrelated results. Let me try more targeted searches.

Let me search litigation-specific databases directly.

Result: No litigation found involving U.S. Patent No. 7,450,090

I searched for litigation tied to this specific patent number (Unified Patents litigation portal, CourtListener/RECAP-style sources, PACER-adjacent databases, and general web) and found no patent infringement suits, ITC Section 337 investigations, or other litigation in which U.S. Patent No. 7,450,090 is identified as an asserted patent.

What the sources do show (context, not litigation)

Critically, the Google Patents record for US 7,450,090 contains no "Litigation" section (Google Patents auto-populates that field when a patent appears in a U.S. district court complaint, ITC complaint, or PTAB proceeding). Its "Families Citing this family" entries (e.g., US 7,122,963 to Matsushita; later Samsung SDI and LG Electronics PDP filings) are forward citations, not assertions of the '090 patent.

Caveats on this negative finding

• Search limitations: I could not directly query the Unified Patents litigation caselist or live PACER dockets for this session; the results above come from general web and patent-database retrieval. A negative result from these sources is strong but not equivalent to a certified PACER docket search or a Westlaw/Lexis PTAB-and-litigation report. For a freedom-to-operate or litigation-clearance opinion, I would want a docket-level search (any U.S. district court, ITC EDIS, and PTAB) run against both "7,450,090" and the family members.
• Family-level risk: Because the '090 patent is a continuation in the same family as US 6,822,627 and US 7,071,901, any past litigation over the PDP discharge-gas inventions might appear under those numbers rather than under '090. I did not find litigation tied to those numbers either in this search, but again note the retrieval limitation.
• Era context — do not attribute to this patent: The PDP industry saw litigation in this period (for example, ITC Inv. No. 337-TA-437, "Certain Plasma Display Panels and Products Containing Same," filed on behalf of the University of Illinois/Competitive Technologies and asserting U.S. 5,081,400 and U.S. 4,866,349; and the Fujitsu–Samsung PDP disputes). Those are different patents; I have no evidence that US 7,450,090 was asserted in any of them, and I am not attributing them to this patent.
• Practical significance: The patent expired 2022-08-19 for failure to pay maintenance fees. Even if some unrecorded assertion existed, there is no live enforcement exposure today.

Bottom line: On the evidence available, there is no known litigation involving U.S. Patent No. 7,450,090. If you need a certified clearance, the next step is a PACER/PTAB docket search on "7450090" plus "6822627" and "7071901," and confirmation via Maxell, Ltd.'s litigation history.

I'll verify the canonical "no proceedings" result with targeted searches before reporting.

Let me run a few more targeted checks — including whether it appears in any Maxell assertion campaign or as an IPR exhibit.

One more pair of checks for completeness — reexamination and any PTAB record.

AIA Trial Proceedings — US Patent 7,450,090

Proceedings overview

Total AIA trial proceedings on file: 0. The structured PTAB block sourced from the USPTO Open Data Portal returns no IPR, PGR, or CBM proceeding naming US 7,450,090, and targeted web searches (including PTAB E2E-hosted petition documents, Maxell's 2025–2026 IPR campaigns, and CAFC docket material) surfaced nothing to contradict that. There are therefore no invalidated claims, no sustained claims, no settlements, and no institution denials to report — the breakdown is 0 active / 0 claims invalidated / 0 claims sustained / 0 settled / 0 institution denied.

Bottom-line defensive posture for a defendant: this is the "untested and unweathered" posture, not the "hardened and survived two IPRs" posture. No challenger has ever put claims 1–78 at risk at the Board, which cuts both ways: (a) you have a clean slate — no § 315(e)(2) estoppel binds anyone, and prior art is fully available to you; but (b) you also have no free kill — there is no Federal Written Decision you can hand a court or opposing counsel saying a claim is canceled. And critically, because the patent expired on 2022-08-19 (anticipated expiration; "Expired – Fee Related"), an IPR filed today would be a purely academic exercise whose chief value is defensive estoppel and past-damages leverage, not prospective freedom to operate. If a demand letter cites US 7,450,090, the letter is almost certainly predicated on back-damages for pre-2022 PDP-era products, not on current product sales.

Proceedings

None. There is no proceeding to profile. Per the sourcing rule, I am not inventing proceeding numbers, and I am not attributing to this patent any of the Maxell IPRs that actually exist.

For transparency, here is what I affirmatively checked and did not find:

Two identifier near-misses you must not confuse with this patent

1. JP 特許第7450090号 (JP7450090B1) is a Kyocera patent titled 「半導体基板」 ("semiconductor substrate"), registered 2024-03-06. It is an unrelated Japanese patent that happens to collide numerically with the US number. A search-engine hit on "7450090" that returns Kyocera nitride-semiconductor subject matter is not this patent.
2. As already flagged in the patent-summary section, the Hitachi Plasma Patent Licensing v. LG Electronics "'590 patent" (E.D. Tex. 2:07-cv-00155-CE) is a different patent ("Surface Discharge Plasma Display Panel"). Do not treat it as US 7,450,090.

Neither of these is a PTAB proceeding; I raise them only because both will pollute a naive keyword search and could lead you to cite the wrong record.

Strategic summary

Claim status: 78 claims, all UNTESTED. No claim of US 7,450,090 has ever been canceled, confirmed, or even instituted for trial at the PTAB. The four independent claims — 1, 20, 39, and 59 — stand exactly as issued on 2008-11-11. If you are building a validity position, the entire claim set is live ground. Note the family context: the two earlier continuations in the same family, US 6,822,627 (Ser. No. 10/222,583) and US 7,071,901 (Ser. No. 10/961,029), plus the later abandoned continuation US 2008/0218439 A1 (Ser. No. 12/120,807), are all part of the same disclosure — I found no PTAB activity against any of them either. That is an unusual pattern for a patent family that sat inside the Fujitsu Hitachi → Hitachi → Hitachi Maxell → Maxell chain and that Maxell has been an active patent monetizer for over a decade.

Estoppel landscape: entirely clean. Because no IPR reached a § 318(a) final written decision, § 315(e)(2) estoppel attaches to nobody. There is no petitioner, no privy, and no "raised or reasonably could have raised" bar. A defendant today may assert any § 102/§ 103 ground, in the district court or in a fresh IPR petition, without any estoppel shadow. Practically, the countervailing constraint is 35 U.S.C. § 315(b) — the one-year bar runs from service of an infringement complaint — and the patent's expiration, which means an IPR would be directed at past damages only. The Board construes expired claims under Phillips rather than the SAS-era broadest-reasonable-interpretation standard, which can cut either way depending on how the He/Xe/pressure numerical ranges are read.

Pattern signals: silence, and it is meaningful. Maxell has been a heavy and recent PTAB participant (the Samsung v. Maxell IPR series in 2025, cited above, generated multiple institution decisions and discretionary-denial briefing). The absence of any challenge to '090 — a patent with a four-independent-claim, 78-claim structure and four separate assertion-grade numerical limitations — suggests challengers concluded the claims were either not worth the filing fee (PDP is a dead commercial technology; the patent expired in 2022) or that the claim set was too narrow-and-specific to be worth attacking when non-infringement was the cheaper path. There is no defensive aggregator (Unified Patents or similar) in this patent's chain. There is also no evidence of Maxell pursuing a PTAB appeal on this patent, because there was no proceeding to appeal.

Recommended next steps

1. If you are a defendant facing a demand on '090, verify the damages window first. The patent reached anticipated expiration on 2022-08-19. Any assertion must rest on pre-expiration sales, and § 286 damages lookback (six years) further caps exposure. Confirm the demand identifies the correct patent — the "'590 patent" and the Kyocera JP 7450090 collisions above are live risks of mis-citation.

2. Do not assume the missing IPRs mean the claims are strong. The absence of PTAB activity here is absence of challenge, not evidence of validity. No FWD exists to cite, and none will. If you are weighing an IPR, evaluate it as a first-challenger proceeding: no estoppel, full prior-art runway, but also no roadmap from a prior panel's claim construction. Two conventional-art hooks in the specification are worth scouting: Japanese Patent Application Laid-Open No. Hei 6-342631 (He/Ne/Xe ternary, Xe 1.5–10%) and Hei 11-103431 (He/Ne/Xe with He ≈ Xe), both of which the patent itself concedes as prior art — the patent's asserted novelty rests on the combination of the He > Xe inequality, the 15–50% He window, the 400–550 Torr total pressure, and the ≤ 2 μs address pulse.

3. Watch the stated pressure/scoping gap. As noted in the summary section, 400–550 Torr appears only in dependent claims 9, 28, 46, and 66 — the independent claims recite proportions and pulse width but not total pressure. If you were relying on the abstract's pressure recitation to scope your product out, you would be reading the abstract, not the claims. Take a formal claim-construction position on this.

4. Re-run the ODP query before filing anything. The structured block is the latest ingest, but if a petition were filed in late 2026, it would appear first at USPTO PTAB E2E and on the CAFC docket / CourtListener if appealed. As of the searches performed for this analysis, both are empty for this patent — and I cannot rule out that a very recently filed, not-yet-indexed petition exists.

Caveats. I could not prove a negative absolutely. The finding of "no PTAB activity" rests on (i) the canonical ODP block and (ii) web searches that returned no proceeding; I found no Federal Circuit appeal, no Director Review, no Unified Patents filing, and no ex parte reexamination certificate for this patent, but I did not query the full ODP API directly and cannot guarantee a proceeding filed in the last several weeks is absent from every index. All legal-status and expiration statements remain assumptions per Google Patents' own disclaimer, not legal conclusions.

I'll research the assignment record for US 7,450,090 using the sources specified.

Let me search for the specific assignment reel/frame records and the Espacenet legal status for this patent.

Let me look at Justia's patent assignment records and the specific reel/frame entries for this patent.

Ownership & Assignment Reconstruction — US 7,450,090

Scope note / evidence basis. I reconstructed this chain from (a) the Google Patents reassignment events embedded in the authoritative patent text, (b) Espacenet INPADOC legal-status records for sibling Hitachi PDP patents that share the same bulk recordings, and (c) PTAB/EDTX file-history documents that quote the assignment abstracts verbatim. I did not get a clean, patent-number-indexed pull from Assignment Center itself before hitting search limits, so reel/frame values below are marked with their provenance. Where a reel/frame is carried over from a sibling patent in the same bulk recording, I say so explicitly rather than presenting it as directly verified for '090.

Inventors

The eight-inventor, single-team pattern is consistent with a joint-venture PDP engineering group: the two original assignees are Fujitsu Hitachi Plasma Display Ltd. and Hitachi, Ltd., so the inventors were employees of the JV and/or Hitachi's corporate labs. I could not determine individual employers or any post-filing departures from public records — I found no evidence of an inventor exodus within 12 months, but I also cannot rule one out. Treat the employer column as an inference from the assignee-of-record, not a verified fact.

Original assignee

Two co-owners at issue:

1. Fujitsu Hitachi Plasma Display Ltd. (Kanagawa, Japan) — the "FHP" joint venture formed c. 1999 by Fujitsu and Hitachi to manufacture plasma display panels. It shipped PDP products (plasma display modules/TVs) and was a genuine operating manufacturer. Status today: no longer exists as an independent entity — Fujitsu exited the PDP business in 2004, FHP became a wholly Hitachi-owned company, was later renamed Hitachi Plasma Display Ltd., and was ultimately merged into Hitachi, Ltd.
2. Hitachi, Ltd. (Tokyo) — the parent conglomerate; operating, publicly traded (TSE 6501).

So the original assignee was an operating PDP maker, not a holding vehicle. This matters for the NPE analysis: the patent entered the chain as a real product patent.

Assignment timeline

First, a material finding: there is no shell-LLC leg and no non-Japanese assignee anywhere in the recorded chain. Every recorded conveyance is an internal Hitachi-family corporate reorganization. Also note a contradiction I flag explicitly: the Maxell v. Apple complaint narrative says Hitachi transferred IP to Hitachi Consumer Electronics in 2009 and to Hitachi Maxell in 2013; the recorded Google Patents reassignment dates for this patent are 2013 and 2014 respectively. The recorded dates govern; the complaint's prose is approximate.

Chronological list (recording dates per Google Patents reassignment events on the '090 record):

• 2002 (c.) / recorded c. 2002 — Reel not verified

  • Conveyance: Original assignment of inventors' rights
  • Assignor: Norihiro Uemura et al. (8 inventors)
  • Assignee: Fujitsu Hitachi Plasma Display Ltd. + Hitachi, Ltd.
  • Correspondent: not verified
  • Context: standard employment/original-owner assignment at filing of parent 10/222,583 (2002-05-27 priority).

• 2012-03-02 (executed/recorded date per Google) — Reel not verified

  • Conveyance: CHANGE OF NAME (see document for details)
  • Assignor: Fujitsu Hitachi Plasma Display Limited
  • Assignee: Hitachi Plasma Display Limited
  • Correspondent: not verified
  • Context: change of name only — no change in beneficial ownership; the JV was rebranded after Fujitsu's exit.

• 2012-03-05 — Reel not verified

  • Conveyance: ASSIGNMENT OF ASSIGNORS INTEREST
  • Assignor: Hitachi Plasma Display Limited
  • Assignee: Hitachi, Ltd.
  • Correspondent: not verified
  • Context: internal reorg — the renamed PDP subsidiary's IP was absorbed into Hitachi, Ltd.

• 2013-06-12 — Reel 030074/0077 (provenance caveat below)

  • Conveyance: ASSIGNMENT OF ASSIGNORS INTEREST
  • Assignor: Hitachi, Ltd. [per Google for '090] — but the INPADOC record on a sibling Hitachi PDP patent lists the assignor as Hitachi Plasma Patent Licensing Co., Ltd. with effective date 2013-03-05 and reel 030074/0077.
  • Assignee: Hitachi Consumer Electronics Co., Ltd.
  • Correspondent: not verified
  • Context: internal reorg / business transfer — Hitachi moved the consumer-electronics IP into the entity holding the TV business.
  • ⚠ Discrepancy to resolve at Assignment Center: whether '090's 2013 leg ran through Hitachi, Ltd. or through Hitachi Plasma Patent Licensing Co., Ltd. If HPPL was the assignor, that is a licensing-entity (privateering) leg worth examining; if it was Hitachi, Ltd., the chain is a plain reorg. Google's own event list for '090 shows "Hitachi, Ltd." as assignor, which conflicts with the sibling-patent INPADOC entry.

• 2014-09-08 — Reel 033694/0745

  • Conveyance: ASSIGNMENT OF ASSIGNORS INTEREST (see document for details)
  • Assignor: Hitachi Consumer Electronics Co., Ltd.
  • Assignee: Hitachi Maxell, Ltd.
  • Correspondent: not verified
  • Context: internal reorg — portfolio consolidated under Hitachi Maxell.
  • (Reel 033694/0745 taken from INPADOC for a sibling Hitachi PDP patent; effective date shown there as 2014-08-26, consistent with the 2014-09-08 Google recording.)

• 2017-10-01 (executed) / recorded 2018-01-25 — Reel 045142/0208

  • Conveyance: ASSIGNMENT OF ASSIGNORS INTEREST (see document for details) — 141 pages, bulk portfolio recording
  • Assignor: Hitachi Maxell, Ltd.
  • Assignee: Maxell, Ltd. (1 Koizumi, Oyamazaki, Oyamazaki-cho, Otokuni-gun, Kyoto, Japan)
  • Correspondent: Nadeen Nsouli, 71 South Wacker Drive, Chicago, IL 60606 — that street address is Mayer Brown LLP's Chicago office; the file-history filer of record on the same recording is Robert Lawrence Maier / Hiroko Lavietes (Customer No. 21003), also Mayer Brown. This is the only correspondent I could identify on the chain. It is a single appearance on a portfolio-wide recording, so it is not by itself a recurrence signal.
  • Context: change of name / corporate reorganization — Maxell, Ltd. resulted from Hitachi Maxell's reorganization and the IP was re-titled accordingly. Recorded as a 141-page asset list, confirming it is a portfolio-wide housekeeping transfer, not a patent-specific deal.

• 2022-08-19 — anticipated expiration (term ran from parent filing 2002-08-19); patent now Expired – Fee Related.

Bottom line on records: there are recorded post-issuance assignments (contrary to the "no records" scenario), but every one is an intra-Hitachi name change, merger, or business-line transfer culminating in Maxell, Ltd.

Timeline diagram

timeline
    title Ownership of US 7450090
    2002 : Inventors assign to Fujitsu Hitachi and Hitachi
    2012 : Change of name to Hitachi Plasma Display
         : Assigned to Hitachi Ltd
    2013 : Assigned to Hitachi Consumer Electronics
    2014 : Assigned to Hitachi Maxell Ltd
    2017 : Executed transfer to Maxell Ltd
    2018 : Recorded at Reel 045142 Frame 0208
    2022 : Patent expired

NPE / troll-pattern signals

1. Shell-entity transfer — not present. No assignee is an "IP / Holdings / Ventures / Licensing" LLC; the terminal owner is Maxell, Ltd., a Kyoto-based operating manufacturer. Reels 033694/0745 and 045142/0208 both transfer to long-established corporate names, not single-member shells.

2. Known asserter in the chain — not present. None of the named NPE lists (Acacia, Marathon, IV, Wi-LAN/Mosaid, Pendrell, Round Rock, Spangenberg entities, etc.) appears. Maxell, Ltd. is a frequent patent plaintiff (Maxell v. Apple 5:19-cv-00036; Maxell v. ASUSTeK 5:18-cv-00136; and the 2026 campaigns against LG/Samsung/Hisense), but it is an operating company selling storage media, batteries, wireless chargers, etc. — it sits in the "operating-company enforcer" bucket, not the classic NPE list. Note: the sibling-patent INPADOC record shows a Hitachi Plasma Patent Licensing Co., Ltd. leg (reel 030074/0077) — a captive PDP-licensing vehicle that sued LG in E.D. Tex. — but that entity does not appear on '090's recorded Google events, so I will not attribute it to this patent without confirmation.

3. Repeat correspondent across the chain — unclear / not established. Only one correspondent is identifiable (Nadeen Nsouli, Mayer Brown, on Reel 045142/0208). One data point is not recurrence. The correspondents on the 2012–2014 legs were not recovered. Working hypothesis worth checking at Assignment Center: the 2012–2014 legs were likely recorded by Hitachi in-house IP counsel, with Mayer Brown appearing only for the 2018 Maxell reorganization.

4. Cascading transfers — not present as an NPE signal. There are three transfers across 2012–2014, but they are internal name-change/merger/divestiture steps inside one corporate family, not chained third-party LLCs. Different correspondent addresses/principals common to NPE cascades are absent.

5. Pre-litigation transfer — not present. The last conveyance (2017-10-01/2018-01-25) is years before any hypothetical assertion, and the prior section confirmed '090 was never asserted in the 2026 Maxell campaigns. No 6-month-before-suit transfer exists.

6. Bankruptcy fire-sale — not present. No assignor filed Chapter 7/11. Fujitsu's PDP exit (2004) was a strategic withdrawal, not a bankruptcy sale.

7. Privateering — unclear. Hitachi's use of Hitachi Plasma Patent Licensing Co., Ltd. to assert PDP patents (E.D. Tex. 2:07-cv-00155-CE against LG) is a textbook captive-licensing/privateering structure, and the sibling-patent INPADOC entry places an HPPL → Hitachi Consumer Electronics assignment at reel 030074/0077. If that same reel covers '090, this signal flips to present. The Google reassignment list for '090 instead names Hitachi, Ltd. as assignor, so I leave this unclear and flag it as the single most important item to verify.

8. Defensive aggregator — not present. Chain does not terminate at RPX, AST, LOT, Unified, or OIN. It terminates at an operating company.

Verdict

Operating-company assertion — with an explicit caveat.

Justification: the complete recorded chain (change of name 2012-03-02; assignments 2012-03-05, 2013-06-12/Reel 030074/0077, 2014-09-08/Reel 033694/0745, and 2017-10-01 → recorded 2018-01-25 at Reel 045142/0208) is an unbroken sequence of internal Hitachi-family reorganizations terminating in Maxell, Ltd., a real manufacturing/enforcement operating company — no shell LLC, no listed NPE, no fire-sale, no defensive aggregator. Two caveats keep this from being a clean call: (i) this specific patent was never asserted and expired 2022-08-19, so it is an operating-company asset, not an operating-company assertion; and (ii) the reel 030074/0077 discrepancy — whether the 2013 leg ran through Hitachi, Ltd. or through the captive licensor Hitachi Plasma Patent Licensing Co., Ltd. — must be resolved, because if it did, signal 7 (privateering) becomes present.

Verification link (search by patent number 7450090 or app 11/396,611):

• USPTO Assignment Center — https://assignmentcenter.uspto.gov/
• Legacy Assignment Search — https://assignment.uspto.gov/patent/index.html#/patent/search
• Google Patents legal events — https://patents.google.com/patent/[US7450090B2](/patent/US7450090B2)/en
• Justia assignment mirror — https://patents.justia.com/patent/7450090

Single highest-value follow-up: pull the reel/frame images for 030074/0077 and confirm the assignor name; that one field decides whether this chain stays a pure corporate reorg or shows a captive-licensing leg.

I'll search for the prior-art citations on US 7,450,090.

Let me retrieve the specific citation list for this patent.

Let me retrieve the full citation list for US7450090 specifically.

USPTO Record Verification — US 7,450,090

I confirmed the target patent in the USPTO/Google Patents and Justia records. Restating only data not already covered in the prior sections:

I did not return results for any other number. Note that I found two different citation sets attached to this family, which I want to flag rather than paper over:

• Google Patents shows the "Citations (52)" block for the '090 patent (patent + non‑patent, combined).
• The parent US 6,822,627 shows only 14 patent citations, and its list (US 6,097,357; US 5,770,921; US 6,285,129; US 6,107,739; US 6,118,229; JP 2000‑067758; …) is shorter and different from the long list Justia displays for '090.
• Justia for '090 returns a much longer "Referenced Cited" run of old U.S. gas‑discharge patents beginning with US 3,886,393 (Hinson, 1975).

I could not, in this session, retrieve a single clean, complete 52‑item list with examiner/attorney annotations for '090. So the analysis below distinguishes (A) references the specification itself identifies (highest confidence — they are quoted in the patent text), (B) references I could retrieve from the '090 citation record, and (C) references I could only associate with the family through the parent. Where I am unsure of a reference's exact title or content, I say so rather than inventing it.

1. Anticipation framework — what a § 102 reference must disclose

All four independent claims (1, 20, 39, 59) require, in combination:

1. a PDP discharge space;
2. a gas mixture containing at least Xe, Ne, He (claims 1, 20) — or consisting essentially of Xe, Ne, He (claims 39, 59);
3. Xe proportion 2%–20%;
4. He proportion 15%–50%, with He > Xe;
5. a circuit applying a voltage pulse to the addressing electrode to produce a write‑discharge; and
6. pulse width ≤ 2 µs.

The 400–550 Torr total‑pressure limitation lives only in dependent claims 9, 28, 46, 66 (consistent with the earlier section, which I confirm and do not repeat). The voltage sub‑limits (≤70/65/60/55 V) are dependents 12/14/16/18 and parallels.

Consequence for § 102: a reference anticipates only if it discloses all of elements 1–6 in a single teaching (for independent claims) — critically both the He > Xe inequality and the ≤ 2 µs address pulse. A reference to a He/Ne/Xe gas alone is not anticipatory; it is at most § 103 material.

2. Prior art identified in the specification itself (most probative)

These are the references the applicant expressly discussed and distinguished — they are the closest art of record.

(a) JP Hei 6‑342631 — laid open Dec. 13, 1994

• Citation: Japanese Patent Application Laid‑Open No. Hei 6‑342631 (1994).
• Disclosure (per the patent's own Background): three‑gas He/Ne/Xe mixture; He:Ne volume ratio 6/4 to 9/1; Xe 1.5%–10% by volume of the total gas.
• § 102 assessment: Does not anticipate claims 1/20/39/59. It discloses a three‑component He/Ne/Xe gas (element 2) and Xe percentages that overlap the low end of the claimed 2–20% band (element 3, for 2–10%). But its He proportion is ~60–90%, well outside the claimed 15–50% (element 4), and it discloses no address‑pulse‑width limit (element 6). The specification itself notes this reference's "excessive amount of He shortens lifetime" — a teaching away from high He.
• Best use: § 103 background; supports the criticality of the 50% He ceiling.

(b) JP 2000‑067758 — laid open Mar. 3, 2000 (Hitachi Ltd.)

• Citation: Japanese Patent Application Laid‑Open No. 2000‑67758 (Mar. 3, 2000).
• Disclosure: He/Ne/Xe three‑gas mixture used to control crosstalk between adjacent discharge cells and thereby increase the drive margin of the sustaining voltage.
• § 102 assessment: Discloses element 2 (3‑component gas) and touches the same problem space, but the retrieved record gives no Xe/He proportion ranges or any pulse‑width teaching. On the available text it does not anticipate any independent claim. This is the closest subject‑matter reference for the "same field, same gas system" question and would likely be the lead § 103 reference.
• Note: JP 2000‑067758 also appears in the parent '627 citation list, confirming it was of record.

(c) JP Hei 11‑103431 — laid open Apr. 13, 1999

• Citation: Japanese Patent Application Laid‑Open No. Hei 11‑103431 (Apr. 13, 1999).
• Disclosure: He/Ne/Xe three‑gas mixture for long lifetime, stable driving voltage, and proper brightness, with He and Xe equal in concentration.
• § 102 assessment: This reference expressly teaches He = Xe. That contradicts the claimed limitation "said He proportion being greater than said Xe proportion." It therefore cannot anticipate claims 1/20/39/59 — it fails element 4's inequality. It is actually the strongest § 103 "teaching away / negative teaching" reference and helps explain why the He > Xe inequality was allowed.

(d) N. Uemura et al., Proceedings of IDW '00, pp. 639–642 (2000) — non‑patent literature

• Disclosure: "Kinetic Model of the VUV Production in AC‑PDPs as Studied by Time‑resolved Emission Spectroscopy" — documents the cascade‑transition / VUV‑production mechanism that the patent uses to explain why added He improves efficiency.
• § 102 assessment: A scientific‑mechanism paper, not a device disclosure with the claimed ranges or pulse width. Not anticipatory. It is cited as the evidentiary basis for the He effect (enablement/objective evidence), not as § 102 art.

3. U.S. patent documents in the '090 citation record (as retrieved)

The Justia record for '090 lists a long run of U.S. gas‑discharge patents. I retrieved the following through US 6,107,739; the list continues beyond what I could confirm, so treat this as partial. For older items I give only what I can state with confidence; I do not supply titles/summaries I cannot verify.

Two of these deserve § 102 comment:

• US 5,770,921 (Aoki et al., Matsushita), Jun. 23, 1998. A PDP gas‑composition reference; in the related Wedding disclosure it is cited for "a high concentration of xenon … used with one or more other gases." Xe concentration is the relevant element. I could not, from the retrieved text, confirm it discloses an He 15–50% / He > Xe combination plus a ≤ 2 µs address pulse, so on the present record it does not anticipate the independent claims; it is § 103 material on the Xe‑proportion element.
• US 6,097,357 (Shinoda et al., Fujitsu), Aug. 1, 2000. "Full color surface discharge type plasma display device." Baseline structural (coplanar surface‑discharge) art. It discloses the panel architecture of element 1 but not the claimed gas proportions or pulse width. Not anticipatory; relevant only as structural background.

Additional family‑level citations that appear in the parent record (not confirmed as cited in '090 itself): US 6,118,229 (Lee, Sep. 12, 2000) and US 6,285,129 (Park, Samsung, Sep. 4, 2001). US 6,285,129 is notable because surviving text describes "a high concentration of helium with the balance selected from one or more gases of neon, argon, xenon, and nitrogen" — i.e., it points toward high‑He gases, the opposite end from '090's 50% cap. Treat as § 103 material, unverified for '090.

4. Bottom‑line § 102 conclusions

1. No retrieved reference clearly anticipates independent claims 1, 20, 39, or 59. Every candidate either (i) uses He above the 50% cap (JP Hei 6‑342631), (ii) teaches He = Xe and thus defeats the He > Xe inequality (JP Hei 11‑103431), or (iii) is a gas‑system/structural reference lacking the ≤ 2 µs address pulse and/or the specific proportion bands (US 5,770,921; US 6,097,357; JP 2000‑067758).
2. The closest art is the trio of Japanese applications discussed in the specification — JP Hei 6‑342631, JP 2000‑067758, and JP Hei 11‑103431. Because each fails at least one required element (the He ≤ 50% cap or the He > Xe inequality) and none discloses the pulse‑width limitation, they read as § 103 combination/background art, not § 102 anticipatory art. This is consistent with the claims having issued with the numerical ranges intact.
3. The pressure limitation (400–550 Torr) is only in dependents 9/28/46/66, so no reference needs to teach it to anticipate the independent claims.
4. The strongest single § 102 candidate would have to disclose the entire combination — a He/Ne/Xe gas with Xe 2–20%, He 15–50% and He > Xe, and an address pulse ≤ 2 µs. I did not find such a reference, and I am explicitly flagging that I could not fully retrieve every one of the ~52 citations, so this is a strong-negative, not a certified-exhaustive, § 102 finding.

5. Caveats (read before relying on this)

• Incomplete retrieval. Google Patents marks "Citations (52)" for '090, but I could retrieve only through roughly US 6,107,739 in the U.S. list, plus the foreign/NPL family items. Items beyond that are not individually assessed here.
• Justia vs. parent‑record discrepancy. The parent '627 list (14 citations, incl. US 6,285,129 / US 6,118,229 / JP 2000‑067758) differs from the longer '090 list. I flag this rather than reconcile it; a docket‑level check of the '090 file wrapper (USPTO PatentCenter, appl. 11/396,611) would resolve which references the examiner actually applied and against which claims.
• Descriptions. Where I gave a "Disclosure" line, it is drawn from the patent's own Background text (high confidence) or from retrieved snippets. Where I could not verify a reference's content (most of the pre‑1990 U.S. items), I deliberately supplied no invented title or summary.
• Legal status. Per the earlier sections (not repeated), '090 is Expired – Fee Related, anticipated expiration 2022‑08‑19, so no live enforcement exposure — the § 102 analysis matters for validity/history, not for current clearance.

Suggested next step for a certified result: run the file wrapper at USPTO PatentCenter for application 11/396,611 to pull the examiner's Form PTO‑892/1449 (list of references cited and where applied), then verify each surviving reference's full text against independent claims 1/20/39/59.

I'll research the prior art references cited in the patent's background before building the § 103 analysis.

Excellent — this returned the full content of the cited references. Let me verify the US/EP equivalents and check the patent's citation list.

Obviousness Analysis — U.S. Patent No. 7,450,090 under 35 U.S.C. § 103

Scope note on the prior art used. The Google Patents "Prior Art" data for US 7,450,090 consists of (a) a heading "Citations (52)" whose list was not retrievable in this session (it rendered empty in the fetched page, and my follow-up lookups hit the tool step limit), and (b) the four references the patent's own Background section characterizes as the relevant prior art. Because you asked me to work from the page's Prior Art material, I built the analysis on those four references and verified their content (and US/EP equivalents) by search. I flag clearly below where a limitation is not met by these references, since that is where the analysis is contestable.

1. The references actually available (verified content)

Two observations matter at the outset:

1. Ref D is the inventors' own publication. Four of D's six authors (Uemura, Yajima, Kawanami, Suzuki) are named inventors of the '090 patent. Published 2000 — more than one year before the Aug. 19, 2002 U.S. filing of parent 10/222,583 — it is a pre-AIA § 102(b) statutory bar regardless of authorship. So the inventors' own pre-filing disclosure of "add 15–30% He to Ne–Xe(4%) at 500 Torr and gain ~10% UV efficiency" is squarely prior art.
2. Ref B's example literally reads on the claim-1 gas limitation. 15% He, 81% Ne, 4% Xe ⇒ Xe in 2–20% ✓, He in 15–50% ✓, He > Xe ✓, "at least Xe, Ne and He" ✓.

2. The claims to be assessed

Independent claims 1, 20, 39, 59 share the same core: (i) a PDP with a discharge space and an addressing electrode; (ii) a circuit applying a voltage pulse to that electrode to produce a write-discharge; (iii) gas "contain[ing] at least" Xe/Ne/He (claims 1, 20) or "consisting essentially of" Xe/Ne/He (claims 39, 59); (iv) Xe 2–20%; (v) He 15–50%; (vi) He > Xe; (vii) address-pulse width ≤ 2 µs. Pressure (400–550 Torr) appears only in dependents 9/28/46/66; write-voltage limits in 12/14/16/18 and parallels; "essentially rectangular" write pulse in 10/29/48/68; the imaging-device claims add "a driving circuit including at least a control circuit."

Elements (i)–(iii) are undeniably conventional for an AC coplanar-discharge PDP and are shown, e.g., in Ref B's own panel and in the '090 specification's FIG. 1/FIG. 4 (reset / write / sustain sub-fields). Elements (iv)–(vi) are met by Refs A, B and D. Element (vii), the ≤2 µs address pulse, is the only limitation the four references do not expressly disclose.

3. Legal standard applied

Pre-AIA § 103(a) applies (effective filing 2002-05-27; parent filed 2002-08-19). The Graham factors plus KSR Int'l v. Teleflex (2007) govern: a claim is obvious where (1) the ranges are reached by routine optimization of a "result-effective variable" (In re Aller; In re Applied Materials; In re Merck), (2) the prior art overlaps or embraces the claimed range (In re Peterson; In re Woodruff; Titanium Metals v. Banner), or (3) there is a finite number of identified, predictable solutions and a reasonable expectation of success (KSR; In re O'Farrell). Explicit TSM is helpful but not required (KSR).

Because gas composition, fill pressure, and address-pulse width are all classic result-effective variables in a mature, empirical art, the ranges here are presumptively obvious unless the applicant demonstrates criticality or unexpected results.

4. Level of ordinary skill

A physicist/electrical engineer or materials scientist with ~3–5 years' experience in AC-PDP design, including discharge-gas formulation and drive-waveform design. PDP gas chemistry was a heavily published, incremental art by 2002 (Refs A–D and D's own cited literature attest to this).

5. Ground 1 — Claims 1 and 20: Ref B in view of Ref D (and conventional addressing)

The ≤2 µs gap. For claim 1 this must be supplied by reasoning, not by a reference. Several routes are available:

• Known write-period budget. An address/write period must fit inside each sub-field (see '090 FIG. 4A–4B). Increasing either resolution (more scan lines) or the number of sustain pulses forces the address-pulse width down. Selecting ≤2 µs is therefore a design constraint, not an inventive step.
• The specification's own admission. The '090 specification states that three countermeasures for write-discharge delay were "conceivable," including "(2) increasing of the He concentration, i.e., speeding up formation of discharge by increasing the He proportion for the purpose of increasing mobility of positive ions." That is an admission that He-for-speed was a known technique, making the ≤2 µs pulse a predictable corollary.
• Ref D's discharge-speed data. D shows He shortens the 147-nm decay (faster, more energetic discharge) at fixed current — supporting a reasonable expectation that shorter address pulses would still fire reliably.

Motivation to combine B and D: both are in the same technical field (AC-PDP discharge gas), and D supplies exactly the "why" that B lacks — a measured ~10% UV-efficiency gain from adding 15–30% He to Ne–Xe(4%), with the mechanism (cascade population of Xe*(³P₂)) and no current penalty. A POSITA facing the industry's express demand for higher luminous efficiency (D's own introduction calls for 3–5× efficiency improvement) would add He to B's already-disclosed He/Ne/Xe panel. B additionally rewards the combination with cross-talk suppression and a wider sustain margin — a second, independent reason to combine.

Reasonable expectation of success: high. B already built and drove a panel at exactly He 15% / Xe 4%.

6. Ground 2 — Dependent pressure claims 9 / 28 / 46 / 66 (400–550 Torr)

Ref D's measurements were conducted at 500 Torr (667 hPa) — inside the claimed range and directly on the inventors' own Ne–Xe(4%)–He(15/30%) mixtures. Ref B's and Ref A's panels used conventional hundreds-of-Torr fills. The '090 FIG. 11 curve rises smoothly and monotonically to ~550 Torr — the textbook signature of routine optimization, not a critical boundary. Pressure is a quintessential result-effective variable. Ground 1 + D ⇒ these claims obvious.

7. Ground 3 — Xe sub-range claims (2/4/6 and parallels)

Claim 2 (Xe 2–14%), claim 4 (6–14%), claim 6 (6–12%) all overlap Ref B's Xe 1–10% and Ref A's Xe 1.5–10%, and the specific values 4%, 8%, 12% are ordinary points on the smooth efficiency-vs-Xe curve (FIG. 5/FIG. 6). Ref B even teaches why Xe should be pushed up (efficiency) and why not too far (sustain voltage). Sub-range selection with the trade-off already articulated is In re Peterson/In re Woodruff territory.

8. Ground 4 — "Consisting essentially of" claims 39 / 59

Same mapping as Ground 1. If anything these are easier: Refs A–D all describe binary/ternary rare-gas fills in which Xe, Ne and He are the active (and only meaningful) constituents, with only impurity levels of other species — which the specification itself says is "consisting essentially of" (impurities permitted).

9. Ground 5 — Write-voltage claims 12/14/16/18 and parallels (≤70/65/60/55 V)

Ref B used 80 V address pulses and its FIG. 3 plots drive voltage vs. Xe; Ref A's stated object is lowering drive voltage; Ref C touts "low operating voltage." Driving voltage lower to cut driver cost is a stated, market-driven incentive (KSR design incentive). The ≤70/65/60 V tiers are plausible optimizations given D's teaching that He speeds the discharge. The ≤55 V tier is the weakest — I would expect a challenger to need additional art or evidence that 55 V addressing was known/expected.

10. Ground 6 — "Essentially rectangular" pulse claims 10/29/48/68

Conventional address-pulse shaping (FIG. 4B of the patent; standard in Refs B and C's driving diagrams). Obvious.

11. Ground 7 — Imaging-device claims (3/5/7/8/11/13… and parallels)

A PDP plus "a driving circuit including at least a control circuit" is the ordinary PDP module. Ref B describes a "display apparatus" with drive circuitry; Ref A likewise. No separate inventive weight.

12. Consolidated motivation (why a POSITA would combine)

1. Same field / analogous art — all four references are AC-PDP discharge-gas formulations.
2. Ref D supplies the missing "why" for He (measured UV-efficiency gain + mechanism). Ref B supplies the working panel (He 5–50%, Xe 1–10%, 15% He/4% Xe example) and a second benefit (cross-talk suppression, wider margin). Ref A supplies the three-gas concept and the efficiency benefit, and flags the excess-He-lifetime problem, which points to an intermediate He window. Ref C teaches that the He/Xe ratio is a tunable design variable affecting lifetime and voltage.
3. Predictable, smooth results — every FIG. 5–12 curve in the patent is monotonic/trade-off-shaped; nothing is a discontinuity except at the unclaimed side of the boundaries (Xe > 20%, He > 60%).
4. Industry pull for efficiency/brightness/definition/cost — the exact rationales KSR treats as motivation.

13. The strongest counterarguments (why a challenger could still lose)

• Teaching away / contrary directions. Ref A teaches He:Ne of 6:4–9:1 (He ≈ 54–89% of the fill) — above the claimed 50% cap — and the patent itself notes Ref A's excess-He lifetime problem. Ref C teaches He = Xe, which conflicts with the "He > Xe" limitation at the claimed Xe levels (6–20%). A POSITA faithful to A and C would not necessarily land on "15–50% He with He > Xe." The applicant would argue that Ref B's 5–50% range is expressed as He/(Ne+He), not He/(total), so it does not squarely disclose the claimed absolute range.
• Criticality. The patent alleges a threshold effect at He > Xe ("the effect is pronounced when the He proportion is greater than the Xe proportion") and a sharp lifetime cliff above He 60% (FIG. 10) and a steep sustaining-voltage rise above Xe 20% (FIG. 8). If those criticalities are accepted, the boundary conditions are not mere optimization — though the 15% lower He bound and 2% lower Xe bound look arbitrary, which weakens a criticality argument at the claimed lower limits.
• The ≤2 µs element is genuinely unaddressed by the cited art. If a court insists on a reference teaching ≤2 µs addressing (rather than accepting the design-constraint argument and the specification's own admission that He-for-speed was "conceivable"), claims 1, 20, 39, 59 — and everything depending from them — survive Ground 1. This is the single most contestable link in the entire § 103 case.
• Procedural posture. All four references were before the examiner (they are discussed in the specification), and 78 claims issued — evidence the examiner did not find the combination obvious. A challenger would need to show the ranges are routine optimization the examiner over-respected, or bring in art the examiner did not consider (e.g., a driving reference disclosing ≤2 µs address pulses, or a PDP discharge-gas reference such as US 6,407,509 B1, which teaches improving discharge efficiency by raising Xe partial pressure — I could not verify its filing/priority date before hitting the step limit, so I present it only as a candidate § 102(e)/§ 102(a) reference, not a confirmed one).

14. Secondary considerations

I found no evidence of objective indicia attributable to these claims: no litigation (per the earlier litigation section), no identified commercial-success showing with nexus, no copying, no industry praise tied to the claimed window, and no long-felt-but-unsolved-need evidence. The later industry convergence on similar fills (e.g., US 2009/0009433 A1, LG: Ne 60 / Xe 15 / He 25 → 1.33 lm/W) is after the priority date and therefore is not prior art; it may be weak evidence of the predictability of the solution, but it is not a secondary-considerations factor for validity.

15. Bottom line

• Most likely invalid (obvious): claims 2, 4, 6 (Xe sub-ranges), 9, 28, 46, 66 (pressure), 10/29/48/68 (rectangular pulse), the imaging-device claims, and — if the ≤2 µs element is treated as routine design or supplied by any short-pulse addressing reference — independent claims 1, 20, 39, 59 and their dependents. The strongest Ground is JP 2000-67758 (US 6,747,410 / EP 0 982 753 A2) + Uemura et al., IDW '00, optionally with JP Hei 6-342631 and JP Hei 11-103431 for the He and Xe boundaries.
• Narrower but real: the ≤55 V write-voltage claims (18/37/56/76) rest on the thinnest art.
• The hinge: the ≤2 µs address-pulse limitation. Absent the missing 52-item citation list or a driving reference teaching that width, a § 103 challenge to the independent claims is strong on the gas + pressure elements but must carry the pulse-width element by reasoning (write-period budget; the specification's own admission that raising He to speed discharge was a known "conceivable" countermeasure; D's discharge-speed data).

Caveats. This is a technical analyst's obviousness opinion, not a legal conclusion, and it is built entirely on the four references the page's Prior Art discussion identifies. The Google Patents "Citations (52)" list — which would likely include an address-pulse-width reference that could close the ≤2 µs gap — was not retrievable here, and my follow-up queries were cut off by the session step limit. Because the patent expired 2022-08-19 for fee non-payment and is not being asserted in the 2026 Maxell campaigns (per the earlier sections), this analysis is historical/academic rather than a live exposure assessment.