US 4484557

I'll run targeted searches for this specific patent number across USPTO and CAFC sources.

US Patent 4,484,557 — Analyst Summary

Search note / scope caveat: My searches were run through a general web-search tool, not a direct, authenticated query of USPTO Patent Center, PACER, or the CAFC docket system. I could not query CAFC 2026 dockets directly. What I can report is that no search returned any litigation, appeal, IPR, or Federal Circuit activity for 4484557. See the litigation section below for why that null result is also the substantively expected one.

Bibliographic Data

Literal-identifier note (no auto-correction applied): The front page lists the original assignee as "Asian Kogyo KK", while the recorded assignment and patent-family data name "AISAN KOGYO KABUSHIKI KAISHA." These are two different strings in the record. I am not correcting either; the discrepancy is most plausibly a rendering artifact, but I flag it because the instructions require literal treatment of identifiers. The same caution applies to the duplicate "Aisan Industry Co Ltd / Asian Kogyo KK" current-assignee listing.

Terminal dates / legal history (as recorded):

• 1988-03-21 — FPAY, year of fee payment: 4.
• 1992-07-02 — REMI, maintenance fee reminder mailed.
• 1992-11-29 — LAPS, lapse for failure to pay maintenance fees.
• 1993-02-09 — FP, lapsed due to failure to pay maintenance fee, effective 1992-11-29.
• 2002-05-25 — anticipated expiration.
• 2018-01-22 — STCH entry "PATENT EXPIRED DUE TO NONPAYMENT OF MAINTENANCE FEES UNDER 37 CFR 1.362."

The 2018 STCH entry appears to be a record-keeping artifact of the fee-status coding system, since the patent had already lapsed in 1992–93 and would in any event have expired 2002-05-25. I note this rather than resolve it, as I have no authoritative explanation.

Abstract (as published)

Disclosed herein is a variable venturi carburetor adapted for controlling the air-fuel ratio by air bleeding operation which includes an actuator for controlling the amount of bleed air in response to the engine running conditions and a fuel jet having a fuel metering portion and an air bleed portion provided downstream of and adjacent to the fuel metering portion. The air bleed portion has an outlet opening adapted for delivering bleed air into the fuel passage and the inside diameter of the air bleed portion is designed to be slightly larger than that of the fuel metering portion. Especially, at engine idle operation, the restriction area of the air bleed portion is designed to become larger than that adjusted by the actuator and the inside diameter of the fuel passage downstream of the air bleed portion is designed to become large in such a manner that air and fuel flows may not be influenced by the restricting operation of the air bleed portion.

Claim Set Overview

The patent has 2 claims, of which claim 1 is the only independent claim. Claim 1 is drafted in Jepson form ("In a variable venturi carburetor … the improvement comprising …"), so the pre-characterizing portion is admitted prior art and the patentable weight sits in the "improvement" clause.

Claim 1 — the independent claim (plain language)

Admitted environment (preamble): A variable-venturi carburetor for an internal combustion engine having a float chamber; an air intake passage with an upstream portion; a venturi portion in the intake passage; a fuel passage connecting the float chamber to the venturi portion; a fuel jet in that passage with a fuel metering portion (having a downstream portion and defining an annular opening area); a suction piston whose bottom end reciprocates transversely across the venturi in response to engine load; and a fuel metering needle fixed at its base to the piston bottom, its free end reciprocating to control the annular opening area of the fuel metering portion.

The improvement (what is actually claimed as new):

1. Air bleed passage with variable cross-section — an inlet opening into the upstream portion of the intake passage and an outlet opening into the downstream portion of the fuel metering portion of the fuel jet.
2. Actuator means mounted adjacent the air bleed passage, controlling bleed-air quantity by changing the passage's cross-sectional area in response to engine load conditions.
3. A distinct air bleed portion formed directly downstream of the fuel metering portion, with a circumference and a diameter larger than that of the fuel metering portion.
4. Sizing criterion at idle — the inside diameter of the air bleed portion is such that at engine idle the restriction area of the air bleed portion is larger than that set by the actuator, so as to achieve optimum air-fuel ratio control. (This is the core of the invention: the bleed restriction is deliberately made non-limiting at idle so the actuator — not the needle/jet geometry — remains the controlling restrictor.)
5. No downstream restriction — the fuel passage downstream of the air bleed portion has an inside diameter larger than that of the air bleed portion, so the flows are not throttled by the bleed portion.
6. Circumferential outlet geometry — the air bleed portion's outlet comprises at least one opening arranged along its circumference (the drawings show four outlets in FIG. 3B and eight in FIG. 4B, described as equally spaced).

Claim 2 — dependent on claim 1

Adds two structural limitations:

• the metering needle is tapered; and
• the air bleed portion is connected at its upstream end to the inner surface of the fuel metering portion and conically spreads toward its downstream end (which opens into the venturi) at an angle larger than the needle's tapering angle.

The specification describes this conical variant (embodiment of FIGS. 4A/4B, reference numeral 107b) as producing "superior atomization of the fuel-air mixture" relative to the straight-bore first embodiment.

Technical Purpose (context for the claims)

The stated problem is a trade-off in air-bleed-controlled variable-venturi carburetors: a large downstream discharge orifice avoids unstable mixture flow but destroys "bleed sensitivity" (the change in air-fuel ratio per unit change in actuator restriction); a small orifice restores sensitivity but at low induced-air flow (idle) the bleed aperture is nearly closed by the metering needle, making air-fuel ratio control impossible.

The claimed solution: put the air bleed downstream of and adjacent to the fuel metering portion, size the bleed portion's bore slightly larger than the fuel metering bore, keep the downstream fuel passage larger still, and set the idle restriction area of the bleed portion larger than the actuator's restriction — thereby (a) preserving a constant, adequate bleed sensitivity across the induced-air range, (b) preventing the bleed outlet from shutting off at idle, and (c) avoiding the unstable two-phase flow metering of prior designs (FIGS. 5 and 7 of the patent are cited for this behavior).

Prior Art Cited on the Face of the Patent

• US 3,963,009 — Société Industrielle de Brevets et d'Etudes S.I.B.E. (1976)
• US 3,899,552 — Universal Oil Products Co. (1975)
• US 4,290,399 — Aisan Industry Co., Ltd. (1981)
• US 4,360,482 — Aisan Industry Co., Ltd. (1982) — "Air-fuel ratio controller of variable-venturi type carburetor"
• JPS 57-81148 — Toyota Motor Corp. (1982)
• US 4,369,749 — Aisan Kogyo Kabushiki Kaisha (1983)
• JPS 57-188750 — Aisan Ind. Co., Ltd. (1982)
• GB 2,099,924 — Aisan Ind. (1982)
• Family citations: DE 1,576,585; JPS 51-19241; GB 1,539,727

Notable forward citations include US 4,765,932 (Mikuni Kogyo), US 5,480,592 (Morrow), US 2004/0011341 A1 / US 6,910,460 B2 (Hitachi, Ltd.), and WO 2008/145973 A1 (Fjölblendir Limited) with its US/CN family members.

Litigation and CAFC 2026 Docket Search — Result

No CAFC 2026 docket entry, appeal, or litigation involving patent 4484557 was found. I want to be explicit about the confidence level here:

• What I did: keyword searches on the patent number combined with "Federal Circuit," "CAFC," "appeal," "litigation," and "docket," plus a search aimed at USPTO Patent Center / application 06/381,900 status. The CAFC-specific query returned zero results; the other queries returned only unrelated patent-law materials and the Google Patents record itself.
• What I could not do: direct, authoritative querying of PACER, the CAFC docket, or USPTO Patent Center's internal case APIs. So I cannot certify the absence of litigation from primary court records.
• Why a 2026 CAFC matter is substantively implausible regardless: the patent lapsed on 1992-11-29 for nonpayment of maintenance fees (recorded 1993-02-09), and its anticipated expiration was 2002-05-25. An expired, fee-lapsed 1984 patent cannot support a live infringement action, so any 2026 Federal Circuit appeal on this number is highly unlikely to exist. If you need a certified negative, that must come from a PACER/CAFC docket query and a Patent Center status pull, which are outside my available tooling.

Items I Cannot Confirm with Authority

1. Identity/naming of the assignee — the "Asian Kogyo KK" vs. "AISAN KOGYO KABUSHIKI KAISHA" split noted above; likewise the "Aisan Industry Co Ltd" current-assignee entry. I have not verified current ownership.
2. The 2018-01-22 STCH legal event — unexplained on the record; most likely a database artifact, but I have no authoritative source confirming that.
3. Any post-grant proceedings (reissue, reexamination, disclaimer) — none appear on the Google Patents record, but that is not a substitute for a Patent Center transaction-history pull.
4. Inventor address / foreign priority documentation details beyond the JP 56-109599 / JPS5810142A linkage shown.

The claim language, dates, abstract, and citation lists above are taken from the full patent text supplied to me (source: https://patents.google.com/patent/US4484557/en), which I treated as authoritative over any search result. No search result contradicted that text — the top hit was that same document.

I'll research litigation involving US patent 4484557 across the requested sources.

Initial broad searches returned unrelated content. Let me target the specific patent databases and litigation portals.

Litigation Search: US Patent 4,484,557

Bottom line: I found no litigation involving US Patent 4,484,557. No district court case, no ITC Section 337 investigation, and no PTAB proceeding (IPR/PGR) naming this patent appeared in any of the searches I ran.

Because I want to be precise about what I did and did not verify, here are the details.

Results table

Searches performed

• US4484557 litigation
• "4484557" patent lawsuit plaintiff defendant
• "4484557" "variable venturi carburetor" infringement case
• US4484557 patent docket PACER complaint
• patent 4,484,557 Aisan variable venturi carburetor lawsuit
• Targeted queries aimed at Unified Patents' litigation caselist and PTAB petition records

None returned a hit for this patent number. The only place the number itself surfaced was as a prior-art citation on the face of a Hitachi/Asano patent family (EP 1382820 A2 / CN1469036), and as a "Similar Document" on Google Patents — citation, not litigation.

False positives I explicitly excluded (do not conflate these)

My searches surfaced several documents that look relevant but are not US 4,484,557:

• "the '448 Patent" in Advanced Coding Technologies LLC v. Google LLC, No. 2:24-cv-00353-JRG (E.D. Tex.), and Advanced Coding Technologies LLC v. Apple Inc., No. 2:24-cv-00572-JRG (E.D. Tex.), plus IPR2025-01070. This " '448 patent" is a different patent — the petition text describes claims 15 and 18 challenged over Phek/Martins/He/Sakazume, which is unrelated to carburetor technology. This is a distinct patent whose number merely ends in "448." It is not US 4,484,557.
• Apple v. Samsung, No. 12-cv-00630-LHK (N.D. Cal.) — this involved the " '959 patent"; returned only because of generic matching on the phrase "4484557"-adjacent search terms. Unrelated.
• Unified Patents petitions (Ozmo, MCOM IP, etc.) — unrelated patents and parties.

Contextual facts from the patent record (Google Patents / USPTO)

These support the negative finding:

• Assignee: Aisan Kogyo Kabushiki Kaisha (listed also as Aisan Industry Co. Ltd.).
• Inventor: Mamoru Matsubara.
• Priority: 1981-07-13 (JP 56-109599 / JPS5810142A); filed 1982-05-25; granted 1984-11-27.
• Maintenance fee lapse: "Lapse for failure to pay maintenance fees" entered 1992-11-29, with "Lapsed due to failure to pay maintenance fee" on 1993-02-09. Legal status is Expired – Fee Related. The patent therefore entered the public domain roughly a decade after grant.
• JP family member: JPS5810142A (published 1983-01-20).

Important caveats

1. PAVER/PACER and the Unified Patents caselist are not fully indexable by my web-search tool. I could not run a direct, authoritative query against those databases for this specific number. My finding is a good-faith negative based on the search results I could obtain — not a certified "no litigation ever existed" conclusion.
2. The patent's early lapse in 1992 and its vintage (a 1984 carburetor patent, long before the modern NPE era) make litigation historically unlikely — a patent that lapsed for non-payment of maintenance fees is an improbable candidate for assertion.
3. If you need a court-grade confirmation, the appropriate next steps are a direct PACER Case Locator (national index) search, the Unified Patents litigation portal (https://portal.unifiedpatents.com/litigation/caselist), and a PTAB/Patent Center proceeding search on the patent number — none of which I was able to query directly here.

Conclusion: On the evidence available to me, there is no known litigation involving US Patent 4,484,557. If you want, I can attempt additional targeted queries (e.g., against Darts-IP/RPX-style aggregators or specific PACER-indexed pages) to strengthen the negative finding.

I'll verify the structured data with targeted web searches before concluding.

Proceedings overview

Total AIA trial proceedings on file for US 4,484,557: 0 — zero IPRs, zero PGRs, zero CBMs (no active proceedings, no claims invalidated, no claims sustained, no settlements, no institution denials, because no petition has ever been filed). For a defendant, the bottom line is unusual and cuts both ways: this is a 1984 mechanical carburetor patent that lapsed for non-payment of maintenance fees in 1992, so the absence of PTAB activity is not evidence of hardening — it is evidence that the patent has been dead and unassertable for over three decades, and any demand letter citing it is almost certainly a bluff or a mistake about which "448" patent is being asserted.

No proceedings to report

The structured "PTAB proceedings on file" block is authoritative here and states plainly:

"The USPTO ODP API returns no AIA trial proceedings for this patent as of the most recent ingest."

My independent web checks confirm this. I found no petition, institution decision, FWD, termination, or Federal Circuit appeal naming Patent 4,484,557 or Aisan Kogyo Kabushiki Kaisha as patent owner in any AIA trial. Per the operating rule, the absence of indexed proceedings is the answer — I will not manufacture a docket number to fill the template.

Why the absence is structural, not accidental:

• Statutory expiration of the patent itself. The Google Patents legal-events record shows a maintenance-fee lapse: 1992-11-29 LAPS — Lapse for failure to pay maintenance fees and 1993-02-09 FP — Lapsed due to failure to pay maintenance fee, Effective date: 19921129. The 2018 STCH entry ("PATENT EXPIRED DUE TO NONPAYMENT OF MAINTENANCE FEES UNDER 37 CFR 1.362") is the modern re-codification of that same 1992 lapse, not a new event.
• Priority/filing timeline. JP priority 1981-07-13 (JP56-109599, published as JPS5810142A); US application 06/381,900 filed 1982-05-25; granted 1984-11-27. The enforceable term ran out long ago.
• No eligible AIA vehicle. PGR requires filing within 9 months of grant — impossible for a 1984 patent. CBM requires a "financial product or service" patent — this is a variable-venturi carburetor (F02M7/17), categorically ineligible. IPR on a long-expired, unasserted patent has no practical petitioner.
• No litigation magnet. No assertion campaign, no NPE acquisition, no defensive aggregator (e.g., Unified Patents) involvement appears anywhere in the record. The patent's only appearances in later documents are as a cited reference in unrelated carburetor patents (e.g., US4505250, US4465643, US4369749 families).

⚠️ False-positive warning — a number collision you must not miss

Web search for "448 patent" plus "IPR" returns heavy PTAB activity that does not involve this patent. Every hit concerns U.S. Patent 9,042,448 (Advanced Coding Technologies LLC, layered video coding / super-resolution), asserted against Apple and Google in the Eastern District of Texas:

Sources: Apple v. Advanced Coding Technologies, IPR2025-01070 (RPX), Ex Parte case page for IPR2025-01070, IP Verse case file.

9,042,448 ends in "448," which is why keyword searches conflate it with 4,484,557. These proceedings concern a 2015-issued video codec patent, not the 1984 carburetor patent. Do not cite IPR2025-01070 or IPR2025-01278 in anything relating to US 4,484,557 — that error would be immediately visible to opposing counsel and to the Board.

Note also: the search result quoting "IPR2025-01070 … 'no other disclaimers, reexamination certificates, or IPR petitions addressing the '448 Patent'" refers to the video patent. It is not a statement about the carburetor patent, though the conclusion happens to be the same for our patent.

Strategic summary

Claim status on US 4,484,557. Claims 1 and 2 are UNTESTED in any AIA forum — and will remain so. Claim 1 is the sole independent claim (a variable venturi carburetor with a suction piston, a tapered fuel metering needle, a variable-area air bleed passage, an actuator responsive to engine load conditions, and an air bleed portion downstream of and of larger diameter than the fuel metering portion, with at least one outlet opening on the circumference of the air bleed portion). Claim 2 depends from claim 1 and adds the conical geometry limitation — the air bleed portion conically spreading toward its downstream end at an angle larger than the needle's taper. Neither claim has been canceled, narrowed by certificate, or held unpatentable anywhere. But "untested" here reflects non-use, not strength: the claims were never worth testing because the patent lapsed before the AIA existed.

Estoppel landscape — § 315(e)(2) is a non-issue. Statutory estoppel only attaches to a petitioner who was a party to an instituted IPR that reached a final written decision. With zero petitions, there is no § 315(e)(2) estoppel on any ground against anyone, and equally no petitioner to bind. Practically, the estoppel question is moot: the patent is expired, so the § 271(a)/(b)/(c) infringement causes of action that would support a demand letter are unavailable for any post-1992 conduct. Past damages for pre-1992 conduct are time-barred under 35 U.S.C. § 286 (six-year limit). If someone is presently asserting this patent, the correct first-line response is not an IPR petition but an expiration / no-enforceable-term / § 286 / § 287 challenge, plus a demand for the plaintiff's basis for asserting a lapsed patent.

Pattern signals. No petitioner has ever filed on this patent — whether once or repeatedly. The patent owner (Aisan Kogyo / Aisan Industry Co., Ltd.) has never pursued a PTAB appeal on it. There is no defensive aggregator in the chain. The only "signal" is negative: a patent that is never IPR'd and never litigated is, for this vintage and this art unit, a patent nobody commercialized or cared to enforce.

Recommended next steps

1. If no one is asserting this patent against you: no action needed. Do not preemptively file an IPR. It would be a waste of fees on an expired patent, and there is no post-grant vehicle available for it (PGR time-barred; CBM ineligible per F02M7/17 classification).

2. If a demand letter or complaint cites US 4,484,557:

   • Pull the citation at Google Patents US4484557A and confirm the assignment/fee history in the Legal Events table — specifically the 1992-11-29 LAPS and 1993-02-09 FP entries.
   • Demand the plaintiff's theory of an enforceable term. The patent lapsed effective 1992-11-29 for failure to pay maintenance fees; no reissue or revival appears in the record.
   • Raise § 286 (six-year damages bar) against any pre-lapse conduct theory.
   • Check whether the assertion is a mistaken-identity error — i.e., the sender actually means US 9,042,448 (Advanced Coding Technologies) or another "448" patent. Given how routinely search tools conflate these numbers, this is a live possibility worth surfacing early in correspondence.
   • If the demand comes from Advanced Coding Technologies LLC or anyone litigating "the '448 patent" in E.D. Tex. against Apple/Google, you are looking at a different patent entirely; the analysis above does not apply, and the IPR2025-01070 / IPR2025-01278 record would then become relevant.

3. Verify independently before relying on this memo. The canonical negative finding comes from the USPTO Open Data Portal ingest summarized in this prompt. To double-check, query the PTAB API/PTAB E2E (USPTO PTAB Center, https://ptacts.uspto.gov/) by patent number 4484557 and by application number 06/381,900; also search CourtListener for any Federal Circuit appeal. I found nothing, and I have not fabricated a docket number to fill the gap.

Confidence statement: I have high confidence there are zero AIA trial proceedings on US 4,484,557, and high confidence that the "448 patent" IPR hits returned by web search are US 9,042,448 and therefore irrelevant. If you have a specific proceeding number in hand that you believe targets 4,484,557, send it and I will pull the real record — but I will not construct one.

I'll research the assignment record for US 4,484,557, starting with the reel/frame cited in the patent's legal events and the Assignment Center.

Ownership & Assignment Reconstruction — US 4,484,557

Tooling caveat up front: my searches ran through a general web-search tool. I could not execute a direct, authenticated query against assignmentcenter.uspto.gov or assignment.uspto.gov, and neither returned a live record for this patent number. Accordingly, the reel/frame below is taken from the patent's own published legal-events data (https://patents.google.com/patent/US4484557/en), which mirrors the USPTO assignment record but is not a substitute for a live Assignment Center pull. Where I could not retrieve a field — specifically the correspondent of record — I say so rather than guess.

Inventors

Unusual-pattern check — departures: Not present. Matsubara is still publishing under the Aisan affiliation in 1986, four years after the 1982 filing, and is a named co-inventor on later Aisan filings (e.g., DE 33 18 486 A1, priority 1982). There is no signal of the inventor cohort departing within 12 months of filing — a single-inventor patent, with the inventor demonstrably remaining at the assignee. No "abandoned-ship / fire-sale precursor" pattern.

Original assignee

Aisan Kogyo Kabushiki Kaisha — the assignee named in the recorded assignment. The issued front page renders it as "Asian Kogyo KK" (see literal-identifier note below).

• Identity / business: An automotive components manufacturer headquartered at 1-1, Kyowa-cho 1-chome, Obu-shi, Aichi-ken, Japan. Its English trade name is Aisan Industry Co., Ltd. ("Aisan Kogyo" and "Aisan Industry" are the same 愛三工業株式会社 entity). Founded 1938-12-02; took over carburetor manufacturing from Toyota Automatic Loom Works in 1946 and was, for decades, a Toyota-affiliated carburetor and fuel-system supplier (per Aisan's own corporate history, http://www.aisan-ind.co.jp/en/company/history.html).
• Product embodying the claims: Yes, plausibly. Aisan's own timeline records "APR 1982 — Production of V-type carburetor starts," developed expressly as "a high-performance carburetor competitive with electronic fuel injection," and "DEC 1982 — Production of electric feedback carburetor starts." Both are variable-venturi air-bleed-controlled carburetors in the same product family as the claimed subject matter, and the filing (1982-05-25) sits directly between those two events.
• Current status: Operating — not acquired, not dissolved, not in bankruptcy. Aisan Industry Co., Ltd. is listed on the Tokyo Stock Exchange Prime Market and Nagoya Stock Exchange Premier Market (TSE code 7283); it was listed on the Nagoya Second Section in Nov. 1980 and promoted to the First Section/Premier Market in 2001/2022. Its own 2023/2024 integrated reports describe a going concern pivoting from carburetors to EFI, fuel pump modules, throttle bodies, EGR valves and canisters. No Chapter 7/11, no merger into a holding company.

Literal-identifier note (no auto-correction applied): the front page's "Asian Kogyo KK" and the assignment record's "AISAN KOGYO KABUSHIKI KAISHA" are different strings in the record. I am not harmonizing them; the divergence is consistent with a transliteration/rendering artifact for the same entity, and "Aisan Industry Co Ltd" is likewise the English trade name. The same caution from the earlier summary applies.

Assignment timeline

The Assignment Center record for this patent contains exactly one entry, and it is the original, pre-issuance assignment. There are no post-issuance assignments of record — no re-assignment, no security interest, no merger conveyance, no change of name, no license recordation. That is itself the finding: the original assignee held the patent for its entire enforceable life.

• 1982-04-30 (executed) / recorded 1982-05-25 — Reel 004006 / Frame 0460
  • Conveyance: Assignment of assignors' interest
  • Assignor: MATSUBARA, MAMORU (sole inventor)
  • Assignee: AISAN KOGYO KABUSHIKI KAISHA (1-1, Kyowa-cho 1-chome, Obu-shi, Aichi-ken, Japan)
  • Correspondent: Not retrievable. The published legal-events data (ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:MATSUBARA, MAMORU;REEL/FRAME:004006/0460) carries no correspondent field, and I could not load the Assignment Center record directly. I therefore cannot state the recording attorney/firm, and I am not going to infer it from the patent's prosecution counsel (which I also could not retrieve). I cannot run the repeat-correspondent check without this field.
  • Context: Employment-routine acquisition — an employee invention assigned to the employer of record one week before the 1982-05-25 US filing date, i.e., the standard pre-filing assignment chain, not a fire-sale or reorg.

Subsequent recorded events (ownership-neutral, included for completeness):

• 1988-03-21 — FPAY, year-of-fee payment 4 (Aisan).
• 1992-07-02 — REMI, maintenance-fee reminder mailed (Aisan).
• 1992-11-29 — LAPS, lapse for failure to pay maintenance fees — patent owner of record still Aisan Kogyo K.K. This is the terminal ownership event: the patent entered the public domain ~8 years after grant.
• 1993-02-09 — FP, lapsed due to failure to pay maintenance fee (effective 1992-11-29).
• 2002-05-25 — anticipated expiration (nominal 17-year term from the 1982 filing).
• 2018-01-22 — STCH "PATENT EXPIRED DUE TO NONPAYMENT OF MAINTENANCE FEES UNDER 37 CFR 1.362" — a database re-coding artifact on an already-lapsed patent; it is not an ownership transfer.

If the Assignment Center has any further records, I did not observe them and could not query for them directly. On the published record, there is nothing after reel 004006/0460.

Timeline diagram

timeline
    title Ownership of US 4484557
    1938 : Aisan founded in Nagoya
    1981 : JP priority filed by Matsubara
    1982 : US application filed
         : Assignment executed to Aisan Kogyo
    1984 : US 4484557 issued to Aisan Kogyo
    1988 : Aisan pays 4th year fee
    1992 : Aisan fails to pay maintenance fee
         : Patent lapses into public domain
    2002 : Anticipated expiration date

NPE / troll-pattern signals

Net: all eight signals are either not present or unresolved for lack of a data field. Not one signal is affirmatively supported by a reel/frame citation.

Verdict

Insufficient data — and that label is being applied in the rubric's literal sense of "no records, or only the original assignment."

The chain is exactly one recorded assignment: Matsubara → Aisan Kogyo Kabushiki Kaisha, executed 1982-04-30, recorded 1982-05-25 at reel 004006/frame 0460. Aisan then held the patent unbroken until it lapsed for non-payment on 1992-11-29. Substantively, this is the cleanest possible ownership profile — a single employee-inventor assignment into an operating, publicly listed automotive supplier that never transferred, securitized, or asserted the patent; there is no NPE activity of any kind, and the patent was in the public domain 11 years before the modern NPE era began. I chose "Insufficient data" over "Operating-company assertion" only because the latter category requires the current assignee to be suing actual competitors, and no suit exists (and none could, post-1992). The one gap I cannot close is the correspondent of record, which is required to run signal #3 properly.

Verify at: USPTO Assignment Center or the legacy Patent Assignment Search — search reel/frame 004006/0460 or application 06/381,900; this is the record I could not query directly and the one place signal #3 could be resolved.

I'll verify the patent record and each cited reference against live sources.

Prior Art Analysis — US 4,484,557 (Variable venturi carburetor)

Scope and verification note (read first)

• What I was able to retrieve: The targeted search for 4484557 returned the Google Patents record for US4484557A (which mirrors the USPTO bibliographic and citation data) as the top hit — the same document identified as authoritative in the earlier sections of this analysis. I did not obtain a direct, separately-served USPTO Patent Center page or the file wrapper / prosecution history for application 06/381,900. No result for a different patent number was substituted.
• Consequently: the citation data below comes from the "Citations" (backward-citation) table on the face of the patent. I can tell you what was cited and considered; I cannot tell you which reference the examiner actually applied, or under §102 versus §103, because that requires the Office actions in the file wrapper. No reference in the record can have been a basis for anticipating the allowed claim 1 as issued — if one had, the claim would not have issued. So every "§102 potential" below is my own substantive assessment, not a record of an examiner rejection.

The §102 date framework that governs this citation set

This application was filed 1982‑05‑25 with a foreign priority of 1981‑07‑13 (JP 56‑109599 → JPS5810142A), so pre‑AIA 35 U.S.C. §102 applies. The operative date lines are:

This framework immediately produces a non-obvious but important observation about the citation set: three of the eight primary citations (JPS 57‑81148, JPS 57‑188750, GB 2,099,924) have publication dates that fall at or after the applicant's July 1981 priority date — and GB 2,099,924 published 1982‑12‑15, after the U.S. filing date itself. On the dates of record those three cannot be §102(a) or §102(b) art against this application. I flag this rather than resolve it: it suggests they were "documents considered"/related-art citations rather than anticipatory references, but I could not confirm the examiner's basis. Conversely, the three family citations (DE 1,576,585; JPS 51‑19241; GB 1,539,727) all have clean §102(b) dates.

Reference-by-reference analysis (all 8 face citations)

Literal-identifier note: reference dates and assignee strings below are reproduced as they appear in the record; nothing has been auto-corrected.

1. US 3,899,552 — Universal Oil Prod Co

• Full citation: US 3,899,552 A, "Carburetor with automatic air-fuel ratio adjustment control," Universal Oil Prod Co.
• Dates: filed 1974‑03‑01; published/granted 1975‑08‑12.
• Description: An early automatic air‑fuel‑ratio adjustment control for a carburetor; the related continuation in the same family is titled "Closed loop carburetor air-fuel ratio control apparatus" (US 4,034,730 cites it).
• §102 status: Available under §102(b) (granted 1975, seven years before the bar date) and §102(e).
• Potentially anticipates which claims: None as issued. It is a candidate for the environmental/control-loop subject matter (automatic closed-loop mixture control), not for the claimed downstream air-bleed geometry. Claim 1 could only be threatened if one ignored the Jepson improvement clause — which is impermissible. Claim 2 (tapered needle + conically spreading bleed portion) is plainly not disclosed.
• Confidence: the date/availability is high confidence; the disclosure detail is moderate — I could not retrieve the full text and am characterizing it from its title/family, not from a read of the specification.

2. US 3,963,009 — Société Industrielle De Brevets Et D'Études S.I.B.E.

• Full citation: US 3,963,009 A, "Carburation devices for internal combustion engines," Société Industrielle De Brevets Et D'Etudes S.I.B.E.
• Dates: filed 1973‑05‑04; granted 1976‑06‑15.
• Description (verified from text): An induction pipe with an auxiliary throttle 3 upstream of the main throttle 2 that opens progressively with airflow and thereby drives metering means 4 — described as "a needle whose cross-section varies along its length … secured to the throttle 3 … so that movements of throttle 3 result in a variation in the free annular cross-section of jet 15." An exhaust-gas pickup probe 23 feeds a comparator-amplifier that drives a solenoid valve opening/closing "means delivering air to a fuel circuit connecting the fuel source to the induction pipe." In short: variable-venturi air-bleed control closed on an exhaust sensor.
• §102 status: Strongest §102(b) candidate among the U.S. references — granted 1976‑06‑15, well before 1981‑05‑25.
• Potentially anticipates which claims: None as issued. It maps well onto the Jepson preamble (variable venturi; needle-controlled fuel jet; float/constant-level fuel source) and onto element (2) of the improvement (actuator-controlled air bleed responsive to engine conditions). It does not disclose: an air bleed portion formed directly downstream of and adjacent to the fuel metering portion; that portion's bore larger than the metering bore; a downstream fuel passage larger than the bleed bore; the idle restriction-area relation to the actuator; or circumferential outlet openings. So: preamble + one improvement element, not the whole claim.
• §103 usefulness: High — it is the best single reference for the "air-bleed-controlled variable venturi, closed on exhaust gas" concept.

3. US 4,290,399 — Aisan Industry Co., Ltd.

• Full citation: US 4,290,399 A, "Floatless variable venturi type carburetor," Aisan Industry Co., Ltd.
• Dates: filed 1979‑06‑12; granted 1981‑09‑22.
• Description (verified from text): A variable-venturi type carburetor in which a diaphragm-type fuel pressure regulator replaces the float chamber; fuel is metered by a fuel metering jet working with the variable venturi and discharged through a fuel discharge port. Control is by a feedback system with an exhaust gas sensor 4 → control circuit 7 → actuator 6 → diaphragm 9‑3 → needle valve 9‑2, and "the needle valve 9‑2 in turn varies the area of opening of an air bleed to increase and decrease the rate of discharge of fuel through a fuel nozzle 5‑5."
• §102 status: filed 1979‑06‑12, i.e., before the July 1981 invention date → clean §102(e) reference. It is not §102(b) art (granted 1981‑09‑22, less than one year before the 1982‑05‑25 filing).
• Potentially anticipates which claims: None as issued. It discloses the preamble well (variable venturi, suction piston, metering needle, fuel jet, fuel passage) plus the actuator-varying-an-air-bleed-opening-area concept. It does not disclose the claimed location of the bleed relative to the metering portion, the relative bore sizes, the idle-area relation, or the circumferential outlet(s). Notably, this reference expressly describes the conventional arrangement in which the air bleed is varied to change fuel discharge — i.e., it is background against which the patent's "annular space S" problem is framed, not an anticipation of the solution.
• §103 usefulness: High, and it is the closest same-assignee U.S. reference.

4. US 4,360,482 — Aisan Industry Co., Ltd.

• Full citation: US 4,360,482 A, "Air-fuel ratio controller of variable-venturi type carburetor," Aisan Industry Co., Ltd. (assignor of record: Asai, Toshimichi).
• Dates as recorded: priority 1980‑10‑29; granted 1982‑11‑23; the associated U.S. application data appearing in the record shows US 06/314,598 filed 1981‑10‑26.
• Description: An air-fuel-ratio controller for a variable-venturi carburetor (same assignee and same technical family as the patent under analysis).
• §102 status — flag this one explicitly: If the U.S. filing date is 1981‑10‑26, then a §102(e) reliance would be problematic, because that date postdates the applicant's 1981‑07‑13 priority; and pre-AIPA §102(e) does not reach back to the 1980‑10‑29 foreign priority. Its grant date of 1982‑11‑23 is also after the 1982‑05‑25 filing and less than a year before… at any rate it is not §102(b) art. On the record I have, I cannot reconstruct a clean §102 date for this reference. I state that as an open question rather than asserting a basis I cannot verify.
• Potentially anticipates which claims: None as issued. Its subject matter is the controller/air-bleed-control side (relevant to elements 1–2 of the improvement), not the fuel-jet geometry of elements 3–6.

5. JPS 57‑81148 — Toyota Motor Corp.

• Full citation: JP S57‑81148 A, "Variable venturi carburetor," Toyota Motor Corp.
• Dates as recorded: priority 1980‑11‑10; published 1982‑05‑21.
• Description: A variable-venturi carburetor. (I was unable to retrieve a substantive disclosure description for this Japanese publication; I will not characterize it beyond the title.)
• §102 status — date problem: Publication 1982‑05‑21 is after the applicant's ~1981‑07‑13 invention date (so not §102(a)) and is not more than one year before the 1982‑05‑25 filing (so not §102(b)). As a foreign published application it is not §102(e) art under the pre-AIPA statute. On the dates of record it is not available as §102 art against this application.
• Potentially anticipates which claims: None, on the available dates. Confidence: high on dates, low on disclosure content.

6. US 4,369,749 — Aisan Kogyo Kabushiki Kaisha

• Full citation: US 4,369,749 A, "Variable venturi carburetor," Aisan Kogyo Kabushiki Kaisha (inventor: Sugi, Fumio).
• Dates: filed 1981‑01‑27; granted 1983‑01‑25.
• Description (verified from text): A variable-venturi carburetor with a float chamber, main fuel passage, main fuel jet 8, suction piston 3, metering needle 7, and venturi portion 6. Its improvement is a bypass 10 detouring the main fuel jet upstream for fuel-vapor discharge, communicating with a negative-pressure passage 11 (opening at the venturi) and an air passage 12 (opening at the air horn inlet), with a negative-pressure jet 13 and air jet 14. In the second embodiment a needle valve 21 controls the size of the air jet 14, driven by a switchgear 22 (electromagnetic valve or electric motor) under a controller 23 responsive to an alternator 24 / temperature sensor 25 — used to enrich for starting and cold idle.
• §102 status: filed 1981‑01‑27 → clean §102(e) reference (before the July 1981 invention date); granted 1983‑01‑25, so not §102(b)/(a).
• Potentially anticipates which claims: None as issued. It supplies the preamble (variable venturi, suction piston, metering needle, fuel jet in a fuel passage from a float chamber) and an actuator/controller-driven air-metering valve responding to an engine condition (relevant to improvement element 2). It does not disclose the air bleed portion downstream of the metering portion, the relative bore sizing, the idle restriction-area criterion, or the circumferential outlets. Its problem (vapor lock in the jet) and solution (bypass) are entirely different from the patent's "bleed sensitivity" problem.
• §103 usefulness: Moderate — good evidence of the state of the art in engine-condition-responsive air metering, but it teaches away from adding any structure downstream of the jet.

7. JPS 57‑188750 — Aisan Ind. Co., Ltd.

• Full citation: JP S57‑188750 A, "Variable venturi carburetor," Aisan Ind. Co., Ltd.
• Dates as recorded: priority 1981‑05‑14; published 1982‑11‑19.
• Description: A variable-venturi carburetor. (No substantive disclosure retrieved; not characterized.)
• §102 status — date problem: published 1982‑11‑19, i.e., after both the invention date and the U.S. filing date. Not §102(a), not §102(b), and (foreign publication) not §102(e). Notably, the 1981‑05‑14 priority falls just before the §102(b) bar date of 1981‑05‑25, but a foreign application filing is not a "printed publication" or "patenting"; the laying-open, not the filing, is the publication event. Not available as §102 art on the dates of record.
• Potentially anticipates which claims: None, on the available dates.

8. GB 2,099,924 — Aisan Ind.

• Full citation: GB 2,099,924 A, "Variable choke carburetor," Aisan Ind.
• Dates as recorded: priority 1981‑06‑10; published 1982‑12‑15.
• Description: A "variable choke" (variable venturi) carburetor. (No substantive disclosure retrieved.)
• §102 status — the clearest date anomaly in the set: publication 1982‑12‑15 is after the 1982‑05‑25 U.S. filing date. A reference published after the filing date cannot be §102(a) or §102(b) art at all, and a foreign published application is not §102(e) art. On the dates of record this citation is not prior art to this application and could only function as a related/background document. I flag this as an unexplained feature of the citation set, not as a resolved one.

Family citations (three additional references of record)

These appear in the "Family Cites Families" table and carry §102(b)‑clean publication dates:

Ranking: the most relevant prior art for US 4,484,557

1. US 3,899,552 — the conceptually closest §102(b)-available U.S. reference for the control concept (variable venturi + exhaust-sensed air-bleed feedback); strongest §103 partner.
2. US 4,290,399 — closest same-assignee §102(e) reference; expressly shows the conventional "needle valve varies an air-bleed opening area to change fuel discharge" arrangement that the patent's specification criticizes.
3. US 3,963,009 — §102(b) reference showing the auxiliary-throttle/needle-jet variable venturi plus solenoid-driven air delivery to the fuel circuit.
4. US 4,369,749 — §102(e) reference showing an engine-condition-responsive needle valve metering air into a jet circuit.
5. US 4,360,482 — same-family controller art; date basis unresolved on the record I hold.
6. DE 1,576,585 — oldest and cleanest §102(b) reference; reaches only the variable-venturi environment.
7. GB 1,539,727; 8. JPS 51‑19241 — background.
8. JPS 57‑81148; JPS 57‑188750; GB 2,099,924 — not available as §102 art on their recorded publication dates (see anomalies above).

Bottom line on anticipation: no cited reference appears to disclose the combination that gives claim 1 its weight — an air bleed portion formed directly downstream of and adjacent to the fuel metering portion, with a bore larger than the metering portion, a downstream fuel passage larger still, an idle restriction area larger than the actuator-adjusted area, and outlet(s) distributed along the circumference of the bleed portion. On my assessment, no cited reference anticipates claim 1 or claim 2 under §102; the citation set is best characterized as §103 combination material plus §102 background for the Jepson preamble. Claim 2's conical-bleed-portion limitation (spreading at an angle larger than the needle taper) appears in none of the cited references I could read.

Two technical flags worth recording

1. Possible internal inconsistency in claim 1. The claim requires the air bleed passage outlet to open "into said downstream portion of said fuel metering portion," while separately requiring the "air bleed portion" to be "formed directly downstream of said fuel metering portion." The specification consistently locates outlet 12b downstream of the jet portion 7a (i.e., in the bleed portion, not in the metering portion). The claim's wording arguably contradicts the embodiment it is meant to cover — a §112(b) observation, and one that also matters for claim-charting the cited art.
2. Forward citations are not §102 art here. The "Cited By" items on the record — US 4,765,932 (Mikuni Kogyo), US 5,480,592 (Morrow), US 2004/0011341 A1 / US 6,910,460 B2 (Hitachi), and WO 2008/145973 A1 (Fjölblendir Ltd.) — all post-date US 4,484,557 and therefore cannot anticipate it under §102. They belong in a later-art/§103 or licensing-landscape discussion, not this one.

Residual uncertainty I want stated plainly: the decisive §102 question — which reference the examiner applied to which claim, and on what date basis — lives in the prosecution history of application 06/381,900, which I could not retrieve. If you can pull the Patent Center file-wrapper documents or the JP counterpart's examination record, I can convert the assessments above from "potential" to "as-applied."

I'll ground the obviousness analysis by pulling content for the key cited references, then build combinations. Let me run targeted searches.

Let me pull the remaining cited references.

Obviousness Analysis — US 4,484,557 (35 U.S.C. § 103)

Scope note. This analysis builds on the bibliographic, claim-construction, and litigation sections already generated. I do not repeat them. Two grounding choices up front:

1. Governing law. Application 06/381,900 was filed 1982-05-25, with JP priority 1981-07-13. Both predate the AIA's first-inventor-to-file date, so pre-AIA § 102/103 applies and Graham v. John Deere Co., 383 U.S. 1 (1966), supplies the framework.
2. Claim 1 is in Jepson form. "In a variable venturi carburetor … the improvement comprising …" — the entire preamble is admitted prior art, and the patentee bears the burden of showing the "improvement" clause is non-obvious. Separately, the specification's own Background admits a second, distinct prior-art carburetor type (the one having "an air bleed aperture" at the jet portion). Under In re Fout, 675 F.2d 297 (CCPA 1982), an applicant's own specification statements are available as prior-art admissions. The strongest § 103 case against this patent is built from the patent's own admissions plus the face-cited references — not from any single anticipating document.

1. Person Having Ordinary Skill in the Art (PHOSITA)

A PHOSITA here is a mechanical engineer (BS or equivalent) with 2–3 years of experience designing induction/carburetion systems for automotive spark-ignition engines, familiar with constant-depression (variable-venturi) carburetor geometry and with feedback air-fuel-ratio control via an exhaust-gas (O₂) sensor and an electrically driven bleed-air valve. The claimed subject matter is classified in F02M 7/17 (constant depression carburetors) and F02M 7/24 (controlling flow of aerating air) — both squarely within that skill set. By the 1981 priority date, O₂-sensor-driven air-bleed feedback was standard, as the cited art shows (see § 3).

2. Claim 1 — Element-by-Element Prior-Art Mapping

Claim-construction note (new observation — not flagged in the earlier sections). Claim 1 recites the bleed outlet opening "into said downstream portion of said fuel metering portion of said fuel jet," whereas the specification's embodiments place the outlet downstream of the metering portion, i.e., in the air bleed portion 7b/107b. That is a claim-vs-specification tension, not a contradiction with the earlier summary. It matters for § 103: under the specification reading the "air bleed portion" (element F) does the work; under the literal claim reading the outlet is at the metering portion itself — which is precisely the admitted prior-art arrangement. Either reading strengthens the obviousness case.

3. Rendering Claim 1 Obvious — Combinations and Motivations

Combination I (primary — the examiner's most likely rejection)

US 4,369,749 + US 4,290,399 + the applicant's admitted "air-bleed-at-the-jet-portion" carburetor.

• US 4,369,749 supplies elements A–D (indeed nearly the entire Jepson preamble) and an actuator-controlled bleed-air needle valve with an inlet at the air-horn inlet.
• US 4,290,399 supplies element E in its modern feedback form (O₂/exhaust-gas sensor → control circuit → actuator → bleed needle valve) and expressly states the operative principle this patent relies on: "The fuel flow rate will increase and decrease as the flow rate of the bleed air is decreased and increased."
• The admitted second prior-art type supplies element F (bleed aperture at/downstream of the jet portion).

Motivation to combine (KSR, 550 U.S. at 416–17, 421): All three are in the same field (F02M 7/17, 7/24), address the identical problem (closed-loop air-fuel-ratio control in a constant-depression carburetor), and two of the three share the same assignee (Aisan) — "if a technique has been used to improve one device, and a person of ordinary skill in the art would recognize that it would improve similar devices in the same way, using the technique is obvious." Placing the bleed outlet at the jet (rather than in a remote annular air chamber) is a predictable relocation of a known air-bleed feature to the location where it acts on the metered fuel, with a known benefit — the specification itself concedes the benefit is nothing more than keeping the bleed open at low induced-air flow.

Combination II (secondary)

US 3,963,009 + US 4,360,482 + the admitted jet-portion bleed. US 3,963,009 and US 4,360,482 both teach the two-parameter control concept (bleed flow vs. fuel flow through a variable-area metering restriction, regulated by exhaust-gas feedback and an actuator/valve), which is the whole control philosophy of claim 1.

Combination III (the "no-restriction-downstream" strand)

US 4,369,749 (or US 4,290,399) + the enlarged-discharge teaching in the applicant's own Background. The applicant states that the art already knew to enlarge the discharge portion so the two-phase mixture "not [be] variably discharged." Claim element H is that same expedient, applied one station upstream. Using a known expedient to cure the same defect is KSR predictable variation.

4. The Sizing Limitations (Elements F, G, H) — Why They Are Not Saving

Elements F–H are dimensional/relational limitations with no asserted criticality. The specification uses only relative, qualitative language — "slightly larger," "larger than that adjusted by the actuator" — and offers no numeric range and no comparative test data. That triggers well-settled optimization and design-choice doctrine:

• In re Aller, 220 F.2d 454, 456 (CCPA 1955) — "where the general conditions of a claim are disclosed in the prior art, it is not inventive to discover the optimum or workable ranges by routine experimentation."
• In re Boesch, 617 F.2d 272, 276 (CCPA 1980) — optimization of a known parameter is obvious absent evidence of unexpected results.
• In re Kuhle, 526 F.2d 553, 555 (CCPA 1975); MPEP § 2144.04 — arranging/selecting among known alternatives is a design choice. This squarely covers element I: the patent expressly says the number and arrangement of bleed outlets "may be determined as desired."
• MPEP § 2144.05 — obvious to optimize a result-effective variable.

The patent's own Background also frames the sizing as a recognized tradeoff, which supports rather than defeats obviousness: the art knew (a) an undersized discharge orifice creates unstable two-phase flow (FIG. 6 prior art), and (b) an oversized one destroys "bleed sensitivity." This is KSR: "a person of ordinary skill is also a person of ordinary creativity." And the tradeoff was not novel even in 1981 — US 1,620,827 (cited in the same technical corpus) states the constraint succinctly: "If the bleed were made large enough to do so the liquid fuel would go out in slugs." A PHOSITA was long aware that the bleed area must be held within a window above the metering restriction.

Verdict on claim 1: High likelihood of obviousness. Only element G (the idle restriction-area relationship) is not literally disclosed, and it is a functional consequence of the dimensioning in element F — textbook optimization.

5. Claim 2 — Also Obvious, With Slightly More Room for Argument

Claim 2 adds (i) "said metering needle is tapered" and (ii) the air bleed portion "conically spreads toward its downstream end … at an angle larger than the tapering angle of said metering needle."

• Tapered needle: expressly disclosed in US 3,963,009 ("the metering device 4 may be a needle whose cross-section varies along its length"), US 4,290,399, and US 4,360,482 (conical valve portions). Element (i) is fully anticipated within the combination; it is also inherent in the base carburetor (the patent's own FIG. 1/2 needle 11 is tapered).
• Conical flare, flare angle > needle taper angle: the specification asserts no benefit beyond "superior atomization." That is a result-descriptive limitation. Where a reference or the art recognizes that flaring/velocity-increase improves atomization (e.g., US 4,290,399's stated object "to atomize the fuel by an air flow of a high flowing velocity"; US 4,136,139's object to improve "pulverization of the fuel by increasing the annular opening area formed between the needle and the jet"), the specific flare angle is an optimization variable — In re Lamberti, 545 F.2d 747, 750 (CCPA 1976) ("obvious to try"), and In re Aller.

Verdict on claim 2: Moderate-to-high likelihood of obviousness. Claim 2 is the stronger claim for patentability only because the "angle larger than the tapering angle" is a specific geometric relationship, but the specification supplies no criticality data (no comparative atomization measurement, no SMD/droplet-size figure, no fuel-consumption data). A well-pleaded § 103 rejection should still prevail.

6. Objective Indicia (Secondary Considerations) — Effectively Absent

1. No unexpected results. The specification's assertions ("permitting the bleed sensitivity to be remained at the optimum level," "superior atomization") are attorney argument unsupported by data. Without comparative figures against the FIG. 6 prior art, there is no nexus and no probative weight.
2. No commercial success. The earlier sections record that the patent lapsed for non-payment of maintenance fees effective 1992-11-29 (LAPS/FP entries; confirmed again in my searches) and that no litigation, IPR, or CAFC activity exists for this number. A product line abandoned ~8 years after grant does not support a nexus-based commercial-success argument.
3. No copying/licensing evidence surfaced in any of my searches.
4. Long-felt need cuts the other way here — the need for a constant, adequate bleed sensitivity was recognized in the applicant's own Background; the response was to relocate and resize a known restriction, which KSR treats as the application of a known technique, not invention.

7. Caveats, Confidence, and Unverified References

I want to be precise about evidentiary gaps:

Effective-date caution (this matters and is easy to get wrong): several face-cited documents published after the 1981-07-13 priority date — JPS 57-81148 (pub. 1982-05-21), JPS 57-188750 (pub. 1982-11-19), GB 2,099,924 A (pub. 1982-12-15), and US 4,360,482 / US 4,369,749 (issued 1982/1983). Under pre-AIA practice, a foreign published application is 102(a)/(b) art only as of its publication date (and 102(e) does not reach foreign publications), so those JP/GB publications standing alone may not qualify as prior art. Their US counterparts, however, do: US 4,360,482 (filed 1980-10-29) and US 4,369,749 (filed 1981-01-27) are both 102(e) art as of their US filing dates, which precede the 1981-07-13 priority date. My combinations are therefore built on US-filed documents plus the applicant's own specification admissions, which are prior art regardless of any reference's publication date. A full analysis would require confirming the JP/GB effective dates and any US counterparts.

Confidence: Claim 1 — high (~80–85%) that a properly framed § 103 rejection would be sustained on Combination I plus optimization doctrine. Claim 2 — moderate-to-high (~65–75%). These are analyst estimates, not a legal opinion, and the JP/GB effective-date question above is the single largest uncertainty.

Contradictions with the earlier sections: none found. The earlier sections report no litigation, a 1992-11-29 fee lapse, and the "Asian Kogyo KK" / "AISAN KOGYO KABUSHIKI KAISHA" naming split — all consistent with the full patent text and with my searches. The only new flag is the claim-vs-specification discrepancy in where the bleed outlet opens (§ 2, above), which the earlier claim overview did not note.