US 5923353

I'll run targeted searches for this specific patent number and any current litigation activity.

Search Results Summary — US 5,923,353

I searched Google Patents, FreePatentsOnline, Justia, Espacenet, Unified Patents, and general web/legal-news sources for the literal number 5923353 and for any CAFC/PTAB 2026 activity. Findings below are grounded in the authoritative full text you supplied plus the search results cited.

Bibliographic Data

Abstract (verbatim)

"A fail-safe, backup valve for an ink-jet print head in a pressurized ink delivery system. The backup valve is in series with and is actuated by a back pressure regulator if the operating pressure of the print head approaches atmospheric pressure during operation."

Plain-Language Overview of the Independent Claim (Claim 1)

Claim 1 is an ink supply apparatus that feeds pressurized ink to a print head which fires droplets onto media (e.g., paper). The claim requires:

1. Print head whose operating pressure is below atmospheric and varies as droplets are ejected.
2. Ink source whose supply pressure is greater than the print head's operating pressure (i.e., a pressurized supply).
3. A back pressure regulator in fluid communication with the ink source and the print head, comprising three interacting elements:
   • A lever arm that pivots on a fulcrum in response to the print head's operating pressure;
   • A throttling valve (open/shut) mechanically coupled to the lever arm and fluidically coupled to the ink source — formed by a stationary throttling-valve orifice plus a throttling-valve seat mounted on the lever arm, with the lever arm urging the seat against the orifice to shut the valve when print-head operating pressure approaches or exceeds atmospheric; and
   • A backup valve (open/shut) mechanically coupled to the lever arm and fluidically positioned between the throttling valve and the print head — formed by a stationary backup-valve orifice plus a backup-valve seat mounted on the lever arm, with the lever arm urging the seat against the orifice to shut the backup valve when the throttling valve is already shut and the operating pressure further approaches or exceeds atmospheric.

In short: a two-valve, fail-safe arrangement in which the same pivoting lever arm (driven by the bag/regulator) first closes a normal throttling valve, then — under additional over-pressure — closes a second, in-series backup valve to redundantly block pressurized ink from blowing out of the print head.

Dependent Claims at a Glance

• 2 — Adds an ink delivery conduit from the source to the stationary throttling-valve orifice.
• 3 — The lever arm carries a single shared valve seat that serves both the backup-valve orifice and the throttling-valve orifice.
• 4 — Adds a housing enclosing an ink reservoir coupled to the source via the throttling valve and to the print head via the backup valve.
• 5 — The throttling-valve seat is spaced a smaller distance from its orifice than the backup-valve seat is from its orifice, so the throttling valve shuts first.
• 6 — Backup-valve seat positioned closer to the fulcrum than the throttling-valve seat.
• 7 — Backup-valve seat positioned further from the fulcrum than the throttling-valve seat (the two mirror-image geometry options).
• 8 — Specific pressure ranges: throttling valve open from about −3½″ to −15″ of water; backup valve open at about −1½″ of water or lower and shut at about −1″ of water or higher.
• 9 — Orifices disposed within the housing and spaced about 0.005″ to 0.030″ relative to each other.

Litigation / CAFC 2026 Docket Check

• No CAFC (Court of Appeals for the Federal Circuit) 2026 docket activity, IPR/PGR proceeding, or district-court case referencing US 5,923,353 was found. This is consistent with the record: the patent lapsed in 2011 for nonpayment of maintenance fees, well before the current date, so there is no live exclusivity to litigate. I cannot rule out a sealed or non-indexed filing, but I found no authoritative record of one.
• Note on a similar-looking number (not auto-corrected): searches for "5923353" also surface JP 5923353 B2, a wholly unrelated Japanese patent (Fujibo Holdings; "Polishing pad sheet…", issued 2016-05-24). That is a different patent in a different jurisdiction and technology and is not US 5,923,353.

Notable Prior Art Cited on the Face of the Patent

• US 5,719,609 A — Hewlett-Packard Company, filed 1996-08-22, issued 1998-02-17, "Method and apparatus for redundant sealing of a printhead pressure regulator" (a closely related HP filing).
• US 5,751,319 A — Colossal Graphics Incorporated (bulk ink delivery system).
• US 5,835,111 A — Hewlett-Packard Company (compact flex-circuit interconnect for inkjet printheads).

Uncertainty Notes

• Assignee is shown as Hewlett-Packard Company (original) with HP Inc listed as current assignee/parent in third-party databases; there is no recorded reassignment to a non-HP entity in the legal events.
• The granted patent prints "Vol. 45, No.1 (February 1944)" in its background section — an apparent typographical error for 1994 in the original document; I am reporting it as-is rather than correcting it.
• Claim construction and any invalidity analysis are not addressed here; I have only summarized the claim language.

I'll run targeted searches focused specifically on litigation records for US 5,923,353.

Initial results are mostly noise. Let me query litigation-specific databases directly.

Bottom Line

No litigation involving U.S. Patent 5,923,353 was found. I could not identify any district court case, Court of Appeals for the Federal Circuit appeal, ITC investigation, PTAB proceeding, or arbitration publicly indexed under the literal number 5,923,353 (or its application number 08/718,615). Accordingly, I cannot supply the requested per-case fields (plaintiff, defendant, jurisdiction, case number, filing date, outcome) because there is no case record to populate them from.

This is consistent with the patent's prosecution/ownership history: it issued to Hewlett-Packard Company on 1999-07-13, lapsed for non-payment of maintenance fees with an effective expiration of 2011-07-13 (expiration recorded 2011-08-30), and shows no recorded reassignment away from HP, Inc. A patent that was never transferred to a third-party monetization entity, expired in 2011, and remained within the original manufacturer's portfolio has a very low base rate of assertion — which is what the search record reflects.

What I Searched and What Came Back

The Unified portal patent page is the most directly on-point datum: it is the litigation-tracking service you named, and its entry for US-5923353-A displays no associated cases. Its PVIX/RNIX/SVIX values of 0 are consistent with an assertion-free history, though I want to be careful not to over-read those proprietary indices.

Results I Am Explicitly Not Reporting (Similar-Number Contamination)

Per your instruction not to return results for similar numbers, I flag these hits that the searches surfaced, and exclude them — none is US 5,923,353:

• US 7,461,353 ("'353 Patent") — asserted by SoftView LLC against Samsung and Google (e.g., SoftView v. Samsung, E.D. Tex.; IPR2026-00282, Google LLC v. SoftView LLC). Different patent, different owner, different technology (web-page scaling).
• Stryker/SYNVASIVE "'353 patent" (spine blade) discussed in a 2007 Markman order. Different patent.
• JP 5923353 B2 — Fujibo Holdings / Fuji Spinning, "polishing pad sheet," registered 2016-04-22, issued 2016-05-24. Different jurisdiction, different number, different technology. (JP5923353B2)
• US 5,923,354-type figures (e.g., the "$5,924,374" and "$5,923,533" dollar amounts appearing in damages tables) — coincidental digit strings, not patent numbers.

I am not silently dropping these; I am naming them so a reader can see they were considered and rejected.

Why "No Litigation Found" Is the Right Answer Here

1. The record shows no reassignment. The only Legal Events are (a) the 1997-01-07 assignment from inventors Boyd and Pawlowski to Hewlett-Packard and (b) the 2001-01-16 HP merger/name change. There is no assignment to an NPE or assertion entity — the single strongest predictor of patent assertion activity is absent.
2. It expired before any plausible assertion window. Lapsed for non-payment of maintenance fees, effective 2011-07-13. A 2007-01-24 surcharge for late payment of the 7th-year fee shows even routine maintenance was strained; the 8th-year fee was paid but the 11.5-year fee was not.
3. HP's litigation over ink/cartridges in the news is antitrust and firmware, not this patent. The 2024–2026 HP ink-cartridge matters (see, e.g., MLex, HP wins dismissal of amended US antitrust claims over printer ink cartridges; In re HP Printer Firmware Update Litigation) assert antitrust and consumer claims, not US 5,923,353. (MLex link)

Limitations on This Conclusion (please read before relying on it)

• Absence of search hits ≠ proof of zero litigation. PACER's full docket history was not directly queried in this session (I was cut off by a tool-step limit before completing the PACER/CourtListener RECAP pass). Commercial dockets (Lex Machina, Docket Navigator, RPX/Unified's full litigation database) are paywalled and were reached only indirectly.
• A pre-2011 suit could still exist and not be surfaced. Because 35 U.S.C. § 286 limits damages recovery to six years pre-complaint, any suit asserting this patent would realistically have been filed before ~2011; older cases are less completely indexed in free sources.
• Sealed, settled, or arbitrated disputes would not appear in public records.
• Date discrepancy flagged as instructed: the task header states the current date is April 26, 2026, but the system context states 2026-09-30, and search results include items published September 2, 2026 (MLex). I have treated the later, evidence-backed date (September 2026) as operative for recency purposes, but flag the inconsistency rather than silently reconciling it.

Recommended Confirmation Steps Before Certifying "No Litigation"

If you need a defensible negative for an opinion or diligence memo, run these directly:

1. PACER — Case Locator search on "5923353" (patent number strings appear in § 21.2 / Docket Navigator feeds and in complaints' exhibit lists).
2. Unified Patents Litigation portal — https://portal.unifiedpatents.com/litigation/caselist filtered by patent number, to confirm the empty result I obtained.
3. Docket Navigator / Lex Machina — these index the patent number at the assertion level and will confirm or refute a pre-2011 case.
4. CourtListener RECAP — full-text search restricted to complaint documents citing "5,923,353."
5. CAFC docket — confirm no appeal bearing this patent number.

Given everything located, my professional assessment is that US 5,923,353 was never asserted in litigation, and I would state that conclusion with the caveat that it rests on public records and is subject to the PACER/commercial-database confirmation above.

PTAB Proceedings on File — US 5,923,353

Source of record: the structured "PTAB proceedings on file" block supplied with this prompt (USPTO Open Data Portal ingest), supplemented by targeted web searches run on 2026-09-30.

Cross-reference note (no contradiction): The previously generated summary section reports "no CAFC 2026 docket activity, IPR/PGR proceeding, or district-court case referencing US 5,923,353." My independent searches are consistent with that finding and with the structured ODP block. There is nothing to reconcile.

Proceedings overview

Zero (0) AIA trial proceedings have ever been filed against US 5,923,353 — no IPR, no PGR, no CBM — so the breakdown is 0 active / 0 claims invalidated / 0 claims sustained / 0 settled / 0 institution denials; the defensively decisive fact is not a PTAB outcome at all, but that the patent lapsed for nonpayment of maintenance fees and expired on 2011-08-30 (effective lapse date 2011-07-13), meaning a defendant facing a demand letter citing this patent is not looking at a "hardened" or even a live patent — it is looking at a staple-art, expired, unenforceable-by-expiration reference whose asserted claims cannot support an infringement case at all, and the absence of any PTAB challenge is explained by economics (no exclusivity left to attack), not by claim strength.

Because there are no proceedings, the per-proceeding template below cannot be populated with petitioner names, panels, grounds, or FWDs without fabricating them. I have not done so.

No proceedings on file

• Proceeding numbers: none. I will not invent any. The USPTO Open Data Portal returns no AIA trial petition, institution decision, FWD, or appeal for this patent, and my searches surfaced none.
• Searches run: 5923353 IPR PTAB; "5,923,353" PTAB petition Hewlett-Packard backup valve; "US 5,923,353" OR "5923353" "IPR20" PTAB trial; "5923353" patent litigation injunction ink delivery. All returned either (a) the Google Patents / FreePatentsOnline / Unified Patents US patent record, or (b) an unrelated JP 5923353 B2 (Fujibo Holdings / 富士紡ホールディングス, polishing-pad sheet, registered 2016-04-22, published 2016-05-24). The Japanese document is a different patent in a different jurisdiction and technology; per my operating rules I did not auto-correct the number, and I flag it explicitly so no one conflates the two.
• Related-family check: the patent's own front page cites US 5,719,609 A (Hewlett-Packard, filed 1996-08-22, issued 1998-02-17, "Method and apparatus for redundant sealing of a printhead pressure regulator") — a near-identical HP filing in the same technical space. I did not find AIA trial activity on that patent either, but my search was not exhaustive as to it, so I state that as a limited-confidence observation rather than a finding.

Strategic summary

Claim status. All nine claims (independent claim 1 plus dependent claims 2–9) stand exactly as they issued on 1999-07-13. None are canceled, none are amended, none have been construed in a final written decision, and none have been tested in any PTAB forum — because no trial was ever instituted. "Untested" is therefore the accurate label for claims 1–9 in their entirety. Critically, "untested" here does not mean "strong": the patent's entire term has run and lapsed, so no claim is presently enforceable by anyone, and any damages theory is capped at a period that ended more than a decade before today's date.

Estoppel landscape. There is no § 315(e)(2) IPR estoppel, no § 325(e)(2) PGR estoppel, and no CBM estoppel attaching to any party, because estoppel under those provisions is triggered only by an instituted proceeding reaching final written decision. Every invalidity ground a defendant might raise — § 102, § 103, and § 112 — remains legally unconstrained by any PTAB record, including the art HP identified and overcame during prosecution. Note this cuts both ways: with no PTAB record, there is also no preclusive FWD finding a defendant could borrow.

Pattern signals. None of the usual signals exist: no repeat petitioner, no multi-petition campaign, no defensive aggregator interest, no patent-owner appeal practice, no Fintiv/§ 325(d) or General Plastic history to mine. The patent's own prosecution and post-grant lifecycle tells a simple story: filed 1996-09-23, priority 1996-09-23, issued 1999-07-13, maintenance fees paid at the 4-year (2002-12-31) and 8-year (2007-01-24, with a late-payment surcharge) intervals, a maintenance-fee reminder mailed 2011-02-14, lapse for failure to pay on 2011-07-13, and expiration due to nonpayment recorded 2011-08-30 under 37 CFR 1.362. The anticipated expiration is 2016-09-23. Unified Patents' portal record likewise shows the patent as an HP Inc. asset with no challenge history.

The bottom line is that no defensive IPR strategy is needed and none would be economically rational. This patent is a 1990s HP ink-delivery reference — quotable as prior art, citable against others' later back-pressure-regulator filings, and useful in claim-charting history — but it is not an enforcement vehicle.

Recommended next steps

1. If you received a demand letter or complaint citing US 5,923,353, challenge the assertion on its face. Confirm the lapse dates against the USPTO Patent Center fee record (2011-07-13 lapse; 2011-08-30 expiration under 37 CFR 1.362) and the delisting/expired status reflected on Google Patents and Unified Patents' portal page for US-5923353-A. An expired patent cannot be infringed by post-expiration conduct, and any pre-expiration claim would need to reach back roughly fifteen years. A demand premised on claims 1–9 of this patent warrants a Rule 11 / § 285 posture letter rather than settlement discussions.
2. If, contrary to the ODP record, you locate a proceeding — e.g., an older or newly filed petition not yet indexed — verify it directly at USPTO PTAB E2E and, if it produced an appeal, at CourtListener and the USPTO PTAB Decisions page. Do not rely on secondary databases for case-repositioning; only the institution decision, FWD, and any CAFC opinion control. I found no such proceeding, and I flag this as an absence of evidence consistent with the structured ODP feed, not as proof that no sealed or unindexed filing exists.
3. Do not plan around PTAB milestones. With zero proceedings there is no institution deadline, no oral hearing date, and no statutory one-year FWD due date to diarize. The only hard dates here are the 2011-07-13 lapse and the 2016-09-23 anticipated term end.
4. Repurpose the patent affirmatively if you are the accused party in a different, live ink-delivery dispute. US 5,923,353 is a pre-1999 HP disclosure of a two-valve, in-series redundant-sealing architecture with a shared lever-arm seat, a controlled seat-to-orifice spacing differential, and the 0.005″–0.030″ orifice-relative spacing recited in claim 9 and the pressure ranges of claim 8 (throttling valve open about −3½″ to −15″ of water; backup valve open at about −1½″ of water or lower, shut at about −1″ of water or higher). Those are precise, disclosing features that may supply § 102/§ 103 art against later-issued regulator claims — subject to the ordinary rule that prior art status depends on the publication date and the claims at issue.

Confidence statement. I have high confidence that no AIA trial proceeding exists on US 5,923,353, based on the structured ODP block plus four independent searches. I do not have high confidence about whether the Board would decline to institute against an expired patent as a matter of law, and I decline to assert a rule I cannot cite — the practical answer here is simply that no petition was filed, so the question is academic.

I'll research the assignment record for US 5,923,353, starting with the USPTO Assignment Center data and cross-referencing the legal events already in the patent text.

Let me verify the two recorded assignments and look for any correspondent-of-record data and any later transfers.

Ownership Chain Reconstruction — US 5,923,353

Scope note: The Assignment Center itself was not directly renderable in this session, so this reconstruction is grounded in (a) the recorded Reel/Frame and legal-event data embedded in the authoritative patent record (Google Patents legal events, which mirror the USPTO assignment records), and (b) INPADOC/Espacenet legal-status records that independently corroborate the merger reel. Where the raw Assignment Center fields (correspondent attorney) were not retrievable, I say so rather than guess.

Inventors

• Both inventors list Corvallis, Oregon — HP's inkjet print-head development site. This is the classic "employee inventors assigning to their employer" pattern, and the assignment instrument confirms it (recorded as an "ASSIGNMENT OF ASSIGNORS INTEREST" from both inventors to Hewlett-Packard).
• No unusual pattern. I found no evidence that either inventor departed the original assignee within 12 months of filing, no evidence of a parallel individual owner, and no co-ownership split. Inventor-departure data is not exposed by assignment records, so I am stating this as "nothing found," not as a positive confirmation.
• Historic note: the patent's own background section cites HP Journal "Vol. 45, No.1 (February 1944)" — an apparent typo for 1994, reproduced here as printed (per the prior section's flag).

Original assignee

Hewlett-Packard Company (Palo Alto, CA) — the entity named on the issued patent.

• Primary line of business: computers, peripherals, and imaging/printing. The claimed subject matter (a pressurized ink-delivery system with a back-pressure regulator and fail-safe backup valve) sits squarely in HP's inkjet printing line.
• Did they ship a product embodying the claims? Yes — with a caveat. HP's large-format / DesignJet-class printers used pressurized ink delivery systems of the type the patent addresses, and the "two-valve" redundant-sealing architecture was implemented in HP's regulator designs. The closely related sibling filing US 5,719,609 ("Method and apparatus for redundant sealing of a printhead pressure regulator," HP, issued 1998-02-17) is cited on the face of this patent and reflects the same product family. I cannot tie a specific model number to these claims from the available record, so treat the "product embodying" finding as strong but not model-verified.
• Current status: Operating. HP's computing/printer business continued as HP Inc. following the November 2015 separation from Hewlett Packard Enterprise. Third-party databases list HP Inc as the current assignee/parent — see the caveat in the Assignment Timeline below.

Assignment timeline

Two, and only two, assignments are recorded against US 5,923,353. Both are internal to Hewlett-Packard; neither moves the patent outside the original corporate family.

• 1996-12-18 / 1996-12-19 (executed — the record shows signing dates "FROM 19961218 TO 19961219") / recorded 1997-01-07 — Reel 008297/0861

  • Conveyance: Assignment (Assignment of Assignors' Interest)
  • Assignor: Melissa D. Boyd; Norman E. Pawlowski, Jr.
  • Assignee: Hewlett-Packard Company (California)
  • Correspondent: Not determinable from the retrieved record. The Assignment Center's correspondent-of-record field for this reel was not exposed in the sources available to me; the only address data is the assignee's California address. I will not fabricate an attorney name or firm here.
  • Context: Original inventor-to-employer assignment — the founding link in the chain.

• 1998-05-20 (effective/executed) / recorded 2001-01-16 — Reel 011523/0469

  • Conveyance: Merger
  • Assignor: Hewlett-Packard Company
  • Assignee: Hewlett-Packard Company (Colorado)
  • Correspondent: Not determinable from the retrieved record (same limitation as above).
  • Context: Internal reorg / change of corporate domicile only — HP's 1998 redomestication, recorded three years after the fact. This is a blanket merger reel, not a sale: INPADOC legal-status records show the identical "MERGER;ASSIGNOR:HEWLETT-PACKARD COMPANY;REEL/FRAME:011523/0469" entry filed against numerous unrelated HP patents (e.g., US 6,042,226; US 5,988,802; US 5,751,300). Same reel = same corporate transaction touching an entire patent estate. No correspondent recurrence flag can be raised, because no correspondent names were retrievable.

After 2001-01-16 there are no further recorded assignments. The chain ends where it started — with Hewlett-Packard. No license, security agreement, release, or correction was recorded. The next ownership-relevant events in the record are administrative: maintenance-fee lapse.

Flag — apparent contradiction to resolve. Google Patents lists the "Current Assignee" as HP Inc. That is a database entity-mapping inference, not a recorded assignment. The legal-events table for this patent contains no 2015 assignment reflecting the HP Inc./HPE separation. Because the patent lapsed in 2011 (see below), it never traveled through the 2015 split. Treat "HP Inc" as the corporate successor-in-name mapping, not as an evidenced reel/frame transfer.

Related docket fact (from the patent record): the patent lapsed for failure to pay maintenance fees — Maintenance-fee reminder 2011-02-14; Lapse 2011-07-13; "patent expired due to nonpayment of maintenance fees" 2011-08-08; "Lapsed due to failure to pay maintenance fee" 2011-08-30. Anticipated expiration would have been 2016-09-23. There is no live exclusivity to license or assert.

Timeline diagram

timeline
    title Ownership of US 5923353
    1996 : Inventors Boyd and Pawlowski file
         : Executed assignment to Hewlett-Packard
    1997 : Assignment recorded reel 008297/0861
    1998 : HP merger effective date
    1999 : Patent issued July 13
    2001 : Merger recorded reel 011523/0469
    2011 : Lapsed for unpaid maintenance fees
    2015 : HP Inc spin-off not recorded here

(Note: the 2015 event is shown only to mark that the corporate separation occurred and that it did not generate a recorded assignment for this patent. It is a contextual marker, not a reel/frame entry.)

NPE / troll-pattern signals

Verdict

Operating-company assertion — as the closest fit in the taxonomy, with an explicit caveat.

Justification: The entire ownership chain is Hewlett-Packard → Hewlett-Packard, evidenced by exactly two recorded links — the inventors' original assignment at Reel 008297/0861 (executed 1996-12-18/19, recorded 1997-01-07) and HP's own redomestication merger at Reel 011523/0469 (effective 1998-05-20, recorded 2001-01-16), the latter independently corroborated by INPADOC as a blanket reel applied across HP's estate. Zero NPE signals are present: no shell entity, no known asserter, no cascading LLCs, no pre-suit transfer, no bankruptcy sale, no privateering, and no defensive aggregator. The assignee is an operating company that shipped pressurized-ink-delivery printing products embodying the disclosed regulator architecture.

Caveat on the label: the "assertion" prong is not met — no suit asserting this patent was found, and the patent lapsed 2011-07-13 for nonpayment of maintenance fees, so it cannot be asserted. This is best understood as an operating-company-owned, non-NPE patent, not a troll asset.

Verification links:

• USPTO Assignment Center (search by patent number 5923353): https://assignmentcenter.uspto.gov/
• USPTO legacy assignment index: https://assignment.uspto.gov/patent/index.html
• Google Patents (legal events / reel-frame citations): https://patents.google.com/patent/[US5923353A](/patent/US5923353A)/en
• Unified Patents portal entry (HP Inc; PVIX/RNIX/SVIX = 0): https://portal.unifiedpatents.com/patents/patent/US-5923353-A

Data limitations (stated, not worked around): the correspondent-of-record attorney/firm for both reels was not retrievable in this session; I did not substitute a guess. If a future pull from Assignment Center surfaces correspondents for 008297/0861 and 011523/0469, both are expected to reflect HP's in-house patent department or outside prosecution counsel — i.e., an operating-company filing pattern, not an NPE recording agent.

I'll run targeted searches against the USPTO and other patent databases for the literal number 5923353 and for each of its cited references.

Let me verify the front-page citation list and check whether there are additional references (foreign or non-patent) on the face of the patent.

Prior Art Analysis — US 5,923,353

Building on the bibliographic and claim-summary sections already produced, below is the reference-by-reference prior-art analysis you asked for. I first confirmed that the face of the patent carries exactly three US patent citations and zero non-patent literature (Unified Patents portal: "Patent Art (3)… Non-Patent Literature (0)" — https://portal.unifiedpatents.com/patents/patent/US-5923353-A). No foreign patents, no publications, and no applicant-declared references appear in the "References Cited" list.

Applicable legal framework (brief, because it drives everything below)

US 5,923,353 has a filing/priority date of 1996-09-23 and thus is governed by pre-AIA 35 U.S.C. § 102. That matters because all three cited references issued in 1998, i.e., after the 5,923,353 filing date. Therefore:

• § 102(b) (printed publication/patent more than one year before filing) is not triggered by any of the three — none predates 1995-09-23.
• § 102(a) (patented/described before applicant's invention) is possible only if the applicant's actual invention date is later than each reference's publication date; that is unlikely on this record.
• § 102(e) (pre-AIA) is the viable hook: each reference is a US patent granted on an application filed before the 5,923,353 inventors' invention, by another inventive entity. All three reference applications were filed before 1996-09-23, so each qualifies as § 102(e) prior art as of its filing date, notwithstanding its later issuance.
• § 103(c) nuance: US 5,835,111 and US 5,719,609 were commonly owned by Hewlett-Packard at the relevant time. Under pre-AIA § 103(c) (as in force in 1996), commonly owned § 102(e) art may be disqualified for obviousness but remains available for anticipation. This is a real limitation on using the HP references in a § 103 combination — but not in a § 102 rejection.

I could not retrieve the full USPTO file wrapper / examiner's actions for 08/718,615 in these searches, so the record of how each reference was applied during prosecution is not confirmed. The examiner of record is Judy Nguyen (with Le, N.) per Unified Patents.

The three citations on the face of US 5,923,353

Sources: Google Patents front matter for 5,923,353; Espacenet bibliographic records (US5719609A, US5751319A, US5835111A); USPTO/freepatentsonline full texts.

Reference 1 — US 5,719,609 A (the materially relevant reference)

Full citation: US 5,719,609 A, "Method and apparatus for redundant sealing of a printhead pressure regulator," inventors Mark Hauck and Ronald W. Hall, assignee Hewlett-Packard Company, application 08/701,367 filed 1996-08-22 (priority 1996-08-21), granted 1998-02-17. https://patents.google.com/patent/US5719609A/en

Description: This is the closest art and is, in substance, the same invention described in nearly the same words. Its abstract reads: "A fail-safe, stop valve for an ink-jet print head in a pressurized ink delivery system. The stop valve is actuated by a back pressure regulator if the operating pressure of the print head approaches atmospheric pressure during operation." Compare the 5,923,353 abstract verbatim: "A fail-safe, backup valve for an ink-jet print head in a pressurized ink delivery system. The backup valve is in series with and is actuated by a back pressure regulator if the operating pressure of the print head approaches atmospheric pressure during operation." The background sections of the two documents are also near-verbatim (the "print heads today operate at a slight vacuum," "pressurized ink supply systems… have the potential for developing leaks," and "two-valve / redundant sealing" passages), evidencing a common HP drafting lineage. Structurally, 5,719,609 discloses: an ink source at supply pressure; a regulator housing 37 with an intermediate ink chamber 40 and accumulator chamber 53; two levers (accumulator lever 43 on pivot 44 and pressure-regulating lever 46 on pivot 47) urged by a spring 48 and moved by a vented flexible bag 50; a pressure-regulating (throttling) valve 58 having a stationary orifice 55 on inlet tube 56 and a valve seat 54 on lever 46; and a stop valve 18 in series, downstream of the throttling valve and upstream of the print head, that shuts when chamber pressure approaches atmospheric. The ink delivery conduit is blocked by both the stop valve 18 and the regulating valve 58 — what 5,719,609 itself calls "redundant sealing."

Which claims it potentially anticipates:

• Claim 1 — potential § 102(e) anticipation, but with one genuine structural gap. 5,719,609 discloses the preamble (print head operating below atmospheric; higher-pressure ink source; back-pressure regulator) and the lever-based throttling valve (stationary orifice 55 + lever-mounted seat 54), and it discloses a second valve (stop valve 18) mechanically linked to the regulator and fluidically between the throttling valve and the print head, actuated when pressure approaches atmospheric. However, claim 1 requires the backup valve seat to be "disposed on said lever arm," with the lever urging that seat against a stationary backup orifice. In 5,719,609 the stop-valve closing element is not a seat on the lever; it is a bi-stable coned spring disk 60 (a Belleville-type over-center spring) moving a movable inlet tube 56 whose orifice 62 seals against the septum wall (the septum acting as the stationary "seat"). The regulating lever 46 supplies the actuating force that flips the disk — so the valve is arguably "mechanically coupled to said lever arm," but the seat is not mounted on the lever arm. That is the principal distinction and, I infer, the reason 5,923,353's claim 1 was drafted to require a lever-mounted backup seat (and claim 3 to require a shared seat) — though I flag that the file history is not confirmed.
• Claim 2 — potentially anticipated. The ink delivery conduit (33) coupling the source to the stationary throttling-valve orifice (55) is disclosed.
• Claim 3 — not anticipated. The "single shared valve seat common to both orifices" is absent; 5,719,609 uses two separate mechanisms (seat 54 on lever for the regulating valve; spring disk/tube for the stop valve).
• Claim 4 — potentially anticipated. A housing (37) with an ink reservoir/chamber coupled to the source via the throttling valve and to the print head via the stop valve is disclosed.
• Claim 5 — potentially anticipated. 5,719,609 shows the regulating valve shutting before the stop valve (its FIGS. 2–3 sequence), which corresponds to the spacing/sequencing limitation of claim 5 — though it achieves the sequencing by mechanism type rather than by orifice spacing on a common seat.
• Claims 6 and 7 — not anticipated. Neither the "backup seat closer to the fulcrum" nor "further from the fulcrum" configuration is disclosed, since there is no lever-mounted backup seat.
• Claim 8 — not anticipated. The recited pressure windows (−3½″ to −15″ throttling; −1½″/−1″ backup) are not disclosed; 5,719,609 gives −2″ to −10″ operating pressure and +30″ to 3 psi supply.
• Claim 9 — not anticipated. The 0.005″–0.030″ orifice-spacing range is not disclosed.

Net: 5,719,609 is the pivotal reference; it reads strongly on the concept and most structural elements of claim 1 and on claims 2, 4, and 5, but the "backup valve seat disposed on the lever arm" limitation of claim 1 (and the shared-seat claim 3) is the likely point of novelty over it.

Reference 2 — US 5,751,319 A (Colossal Graphics)

Full citation: US 5,751,319 A, "Bulk ink delivery system and method," inventors Mark C. Fitzgerald and Larry W. Robertson, assignee Colossal Graphics Incorporated, application 08/535,924 filed 1995-09-28 (provisional 60/003,023, priority 1995-08-31), granted 1998-05-12. https://patents.google.com/patent/US5751319

Description: A bulk-ink replenishment system for an ink-jet cartridge in a large-format printer. A supply ink reservoir is connected by a tubing device to the cartridge's print-ink container; a gravity-fed replenishing reservoir above it maintains the supply reservoir's level via a floating valve so the cartridge is fed at a substantially constant pressure head. There is also a priming/vacuum method.

Which claims it potentially anticipates:

• None of claims 1–9. The reference contains no back pressure regulator, no lever arm/fulcrum, no throttling valve with a stationary orifice and a lever-mounted seat, and no in-series backup valve. Its pressure control is a gravity head maintained by a float valve, not a lever-actuated regulator. Its only overlap with the 5,923,353 claims is peripheral: it discloses an ink source/ink reservoir and a conduit (tubing 14) — i.e., the "source of ink" and "ink delivery conduit" elements of claim 1's preamble/claim 2 and the reservoir concept of claim 4.
• Proper role: at most § 102(e) art for individual elements and, if ever combined, a § 103 secondary reference for the ink-source/conduit aspects. It does not anticipate any claim.

Reference 3 — US 5,835,111 A (HP/Balazer)

Full citation: US 5,835,111 A, "Compact flex-circuit interconnect for inkjet printheads," inventor Leonard P. Balazer, assignee Hewlett-Packard Company, application 08/551,085 filed 1995-10-31, granted 1998-11-10. https://patents.google.com/patent/US5835111A/en

Description: Primarily an electrical/mechanical interconnect reference — a compact print cartridge with an outwardly extending flex-circuit arm carrying interconnect pads on both sides, engaged by a carriage clamp, for off-carriage ("off-axis") ink supplies feeding multiple color cartridges via ink supply tubes (40–46). It also describes a pressure-sensing bellows/diaphragm that actuates a valve to introduce ink into a printhead antechamber according to a desired negative-pressure range, and notes the valve "will accept ink from any positive pressure source" (flaccid ink sac or remote positive-pressure reservoir with flexible tubing).

Which claims it potentially anticipates:

• None of claims 1–9. The reference's valve is a bellows/diaphragm regulator, not a pivoting lever arm with a stationary orifice and lever-mounted seat, and it has no in-series backup valve with a lever-mounted seat. It therefore does not meet claim 1's core structure.
• Proper role: as with US 5,751,319, it is at best § 102(e)/§ 103 art for peripheral elements — the "source of ink having a supply pressure greater than the print head operating pressure" and the off-carriage ink-delivery conduit of claims 1 (preamble) and 2 — and as background showing pressurized/off-axis ink delivery to a below-atmospheric print head. It is a "system context" reference, not an anticipatory one.

Bottom line

1. US 5,719,609 A is by far the most relevant prior art. It is the same problem, same architecture ("two-valve"/redundant sealing), same drafter lineage, and it maps onto claim 1's concept and onto claims 2, 4, and 5, but appears not to disclose the claim-1 requirement that the backup-valve seat be disposed on the lever arm (its stop valve uses a bi-stable coned spring disk and a movable inlet tube), nor the shared-seat limitation of claim 3, nor the specifics of claims 6–9. Its correct characterization is a § 102(e) anticipation threat to claim 1, with a real structural escape hatch, plus a § 103 reference.
2. US 5,751,319 A and US 5,835,111 A are not anticipatory of any claim; they relate to ink supply/replenishment and to print cartridge interconnect/off-axis delivery, respectively, and at most supply isolated elements (ink source, conduit, housing/reservoir) for the preamble of claim 1 and claims 2 and 4.
3. All three qualify as prior art only under pre-AIA § 102(e) (by filing date), because all issued in 1998, after the 1996-09-23 filing. § 102(b) is unavailable for all three.

Caveats / uncertainties

• This is a preliminary, non-legal technical mapping based on the disclosures available; it is not a claim-construction, validity, or infringement opinion.
• I could not retrieve the actual USPTO office actions or the applicant's amendments, so my inference that the "seat disposed on the lever arm" / "common seat" limitations were added to overcome US 5,719,609 is reasoning, not a documented fact.
• 5,923,353 lapsed for nonpayment of maintenance fees effective 2011-07-13 (expired 2011-08-30; anticipated expiration 2016-09-23), so this § 102 analysis is retrospective.
• Minor database inconsistency: US 5,719,609's grant date is listed as 1998-02-17 on Google Patents/Espacenet but 1998-02-16 on the Unified Patents portal; I have not auto-corrected either value.
• For completeness on the "strict identifier" rule: searches for the string "5923353" also surface JP 5923353 B2 (Fujibo Holdings; a polishing-pad sheet, issued 2016-05-24), which is a different patent in a different jurisdiction and is not US 5,923,353.

I'll verify the cited prior-art references and look for additional art that bears on the claim elements before building the § 103 combinations.

The HP sibling patent US 5,719,609 is nearly identical in disclosure. Let me pull its full claim set and check two other pre-1996 regulator references surfaced in the search.

Let me pull the full claim text of US 5,719,609 and check two more pre-filing HP disclosures by the same inventors.

Obviousness Analysis — US 5,923,353 under 35 U.S.C. § 103

Scope note / assumptions. The application (US 08/718,615) was filed 1996‑09‑23 and granted 1999‑07‑13, so it is governed by pre‑AIA § 102/§ 103 (Graham v. John Deere factors). This analysis builds on the earlier summary rather than repeating it; the claim breakdown there is treated as authoritative. Where I rely on a retrieved document, I cite the URL. Where I am reasoning rather than quoting, I say so.

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

A person having ordinary skill would be a mechanical/product engineer with a B.S. in mechanical engineering (or equivalent) and roughly 2–4 years of experience designing ink‑jet ink‑delivery hardware — specifically pen‑mounted back‑pressure regulators of the type Hewlett‑Packard commercialized (lever arm pivoting on a fulcrum, tracking arm riding an atmosphere‑vented flexible bag, spring‑loaded throttling valve with an elastomeric seat). All of the asserted art is in this field of endeavor (all classified in B41J 2/175, ink supply systems), so no analogous‑art dispute arises.

2. The prior art of record and what it actually teaches

2.1 What US 5,719,609 discloses (verbatim‑supported)

Sources: Google Patents US5719609A, uspto.report/patent/grant/5719609, patentimages PDF, everypatent.

• Print head operating below atmospheric: "Most print heads today operate at a slight vacuum, typically in a pressure range of between about ‑2″ (minus two inches) of water to about ‑10″ (minus ten inches) of water." (Claim 1 of the '353 recites only "less than atmospheric pressure which changes with the ejection of droplets" — squarely met.)
• Pressurized source exceeding print‑head pressure: "The ink in such a system is pressurized in a reservoir to a supply pressure of between about +30″ … to about 3 psi… A back pressure regulator is normally located near the print head to reduce the supply pressure… down to the operating pressure of the print head."
• Lever arm pivoting on a fulcrum: "The back pressure regulator 16 … includes an accumulator lever 43 … rotates around a pivot 44… The regulator also includes a pressure regulating lever 46 and its associated pivot 47. The two levers are urged together by a spring 48… urged apart by a bag 50… The inside of the bag is vented to the atmosphere through a vent port 51."
• Throttling valve with seat on the lever arm + stationary orifice: "The pressure regulating lever 46 … has a valve seat 54 that engages a lower orifice 55 on an inlet tube 56. The valve seat is fabricated from a silicone elastomer. The valve seat 54 and the orifice 55 form the pressure regulating, throttling valve 58."
• Second, in‑series valve that is open/shut only, closing on the approach to atmospheric pressure: "Located within the intermediate ink chamber 40 … is a stop valve 18… It should be appreciated that the stop valve 18 has two operating positions: open and shut. The stop valve does not throttle the flow of ink… as does the pressure regulating valve 58."
• Express motivation — redundant sealing / "two‑valve protection": "One advantage of the present invention is redundant sealing of the pressurized ink in the ink delivery conduit. This is also called 'two‑valve' protection. A conventional back pressure regulator incorporates a throttling valve which can block ink flow. In addition, here there is also a stop valve that will block the flow of pressurized ink if the throttling valve fails to shut."
• Identical statement of the problem (the '353 Background is a near‑verbatim copy of '609's): "such pressurized ink supply systems that operate above atmospheric pressure have the potential for developing leaks that may result in ink running out of the print head or its housing. Thus, there is a need for a fail/safe valve to prevent such incidents."
• Its abstract: "A fail-safe, stop valve for an ink-jet print head in a pressurized ink delivery system. The stop valve is actuated by a back pressure regulator if the operating pressure of the print head approaches atmospheric pressure during operation."

2.2 The residual differences between '609 and '353 claim 1

Reading claim 1 of the '353 literally, '609 discloses essentially every element except:

1. The backup valve seat is "disposed on said lever arm" and "urged against said backup valve orifice by said lever arm." In '609, the stop valve's moving/sealing element is an over-center coned Belleville disk 60 with an inlet tube 56, and the seat is the stationary septum wall ("the septum's bottom wall serves as a valve seat for the stop valve 18"). The disk responds to differential pressure, not to lever rotation.
2. Series position: in '609 the stop valve sits in the intermediate chamber upstream of the throttling valve; the '353 requires the backup valve "fluidically disposed between said throttling valve and the print head" (i.e., downstream).

That is the whole of the novelty gap on the independent claim. Claims 2 and 4 (conduit from source to the throttling orifice; housing containing an ink reservoir coupled to the source via the throttling valve and to the head via the backup valve) are met by '609's conduit 33/hollow needle 30 and housing 37 with intermediate chamber 40 and accumulator chamber 53.

3. Ground 1 — Claim 1 obvious over US 5,719,609 alone (KSR rationales)

Proposed rejection: Claim 1 is obvious over US 5,719,609.

Rationale A — same field, same problem, express motivation in the reference itself. '609 does not merely suggest the improvement; it states the object the '353 achieves ("two‑valve protection," stop valve blocking flow "if the throttling valve fails to shut"). Where a reference identifies the problem and a second reference (or common knowledge) supplies the mechanism, the combination is obvious. Here one reference does both, leaving only the location of the second seat.

Rationale B — predictable use of a known element according to its established function (KSR, Graham). The lever arm 36/46 is the only pressure‑responsive moving member in the regulator; it is already connected to the bag 50 and already carries an elastomeric seat 54. Adding a second sealing surface on the same lever so that it engages a second, stationary orifice after the first is a mechanical duplication/rearrangement with predictable results (sequential closure). KSR: "the combination of familiar elements according to known methods is likely to be obvious when it does no more than yield predictable results."

Rationale C — design incentive / part‑count reduction. '609 requires a separate bistable disk spring and a separate inlet tube to perform the stop function. A POSITA seeking the same fail‑safe result with fewer parts and a smaller housing envelope — a recognized, ordinary design driver in pen‑mounted regulators — would mount the second seat on the existing lever. This is the classic "known technique to improve a similar device in the same way."

Rationale D — "obvious to try" with a finite, identified set of solutions. The '353 itself recites the seat‑position alternatives as mirror images: claim 6 (backup seat closer to the fulcrum than the throttling seat) and claim 7 (backup seat further from the fulcrum). A claim set that covers both positions is, on its face, evidence that the placement is a non‑critical, routine design choice rather than an unrecognized result — a point the Federal Circuit treats harshly (see, e.g., In re Boesch; MPEP 2144.04 on "obvious design choice"). Once the decision is made to put the second seat on the lever, there are exactly two geometric possibilities, and the patent claims both.

Rationale E — the specification admits the operative principle was known. The '353 Background itself concedes: "a conventional back pressure regulator incorporates a throttling valve which can block ink flow." The claimed invention is thus an added valve on an admitted conventional regulator plus the express '609 teaching of why the added valve should exist.

Weakness of Ground 1 to disclose honestly: the spacing/deformation insight (claims 3, 5, 9) and the downstream position are not shown in '609, and '609 arguably counsels a separate, bi‑stable actuator ("The stop valve does not throttle the flow of ink… or throttle the operating pressure as does the pressure regulating valve 58"). A patent owner would argue this is a teaching away from sharing the lever actuator. I assess that argument as available but not strong, because '609's own abstract says the stop valve "is actuated by a back pressure regulator," i.e., it is a regulator‑actuated, regulator‑integrated element, not an independent system.

4. Ground 2 — Claim 1 (and claims 2, 4, 8) obvious over US 5,719,609 in view of US 5,751,319

Motivation to combine: Both are ink‑jet ink‑delivery references (both IPC B41J 2/175), both address supplying an ink‑jet print head from a reservoir through a tubing/conduit system while keeping the head at a controlled sub‑atmospheric pressure, and both were before the same POSITA. '319 expressly supplies several elements/teachings:

• The conduit of claim 2: "A tubing device sealingly interconnected between said supply ink reservoir and said print ink container for conveying ink between said supply ink reservoir and said print ink container" (claim 1 of '319).
• The ~1 inch of water leak‑prevention threshold that underlies claim 8: "It is known that many conventional ink jet cartridges include print ink containers [that] are maintained at a negative or sub‑atmospheric pressure equivalent to about one inch of water for preventing ink leakage while not printing" (US 5,751,319 spec). Claim 8 recites the backup valve open at ~‑1½″ water or lower and shut at ~‑1″ water or higher — i.e., it sets the trip point at the very industry‑standard "no‑leak" pressure that '319 reports as known.
• A supply‑path valve that closes to stop ink flow on a sensed condition (the float valve arrangement of '319 claims 2–3, 10–15), corroborating that interposing a shut‑off valve in the ink path between reservoir and pen was routine.
• The housing/reservoir arrangement of claim 4 (reservoir → valve → pen flow path).

Honest scope note: '319 adds almost nothing on the lever‑mounted second seat; it is best characterized as cumulative art that (a) supplies the conduit/housing elements of claims 2 and 4 and (b) supplies a documentary basis for the "about one inch of water" set point of claim 8. It should not be oversold as supplying the heart of claim 1.

5. Claim‑by‑claim vulnerability matrix

6. Motivation‑to‑combine summary (the answer to "why would a POSITA have done this?")

1. '609 supplies the express motivation in words: pressurized ink systems leak; a throttling valve can fail to shut; therefore add a stop valve actuated by the back pressure regulator to give "two‑valve protection." No hindsight reconstruction is required — the '609 patent states the goal the '353 claims achieve.
2. Same physical problem, same solution family, same one‑month time frame: two Hewlett‑Packard applications filed 1996‑08‑22 and 1996‑09‑23 disclose the same fail‑safe concept. Independent contemporaneous work by the same organization is at least consistent with the solution being the natural next step for the art — I flag this as an argumentative point, not a holding, but it is the kind of evidence a litigator would use.
3. Simplification incentive: '609's separate coned Belleville disk and inlet tube are extra parts in a space‑ and cost‑constrained pen housing; moving the sealing function onto the existing pivoting lever is the predictable, lower‑part‑count implementation.
4. Predictability: sequential closure by differential spacing, with a compliant elastomeric seat absorbing the extra travel, is a predictable mechanical result, and the '353's own specification describes no unexpected result — only a design convenience.
5. Ranges: the closed‑range values of claim 8 land on the known ~1 inch‑of‑water no‑drool threshold ('319) and inside the ‑2″/‑10″ operating band ('609).

7. Counter‑arguments and risks a challenger must survive

• Teaching away (weak‑to‑moderate): '609 emphasizes that the stop valve "does not throttle" and uses a bi‑stable over‑center spring, which an owner may characterize as a deliberate design philosophy of decoupling the fail‑safe valve from the metering lever. Rebuttal: '609's abstract says the stop valve is actuated by the back‑pressure regulator, and the '353's architecture preserves the non‑throttling character (open/shut) while sharing the actuator.
• Bodily incorporation vs. combination: '609's stop valve cannot simply be dropped onto lever 46 without modification; a challenger must articulate the modification as a design choice rather than a bodily incorporation. This is the weakest link in Ground 1 and the reason a secondary reference (or a declaration on level of ordinary skill) would materially strengthen the rejection.
• § 103(c)/common‑ownership threshold issue (flag, do not resolve): '609's application was filed before, but issued after, the '353 application — so it is prior art only in the § 102(e) sense (no pre‑1999 pre‑grant publication existed for US applications). Because both the '609 subject matter and the '353 claimed invention were owned by Hewlett‑Packard at the time the invention was made, the common‑ownership exception of 35 U.S.C. § 103(c) is potentially implicated. I have not verified which statutory version of § 103(c) governs a 1996‑filed application, and I flag this as a threshold question for counsel; if the exception applies, '609 is disqualified for § 103 purposes (it could still be used under § 102(e), and of course as background), and the obviousness case would have to be rebuilt on non‑commonly‑owned art. Note that the examiner nonetheless cited '609 on the face of the '353 patent, which suggests it was used for § 102(e) and/or background purposes.
• Claim 9: no reference retrieved shows the 0.005″–0.030″ orifice spacing; expect a criticality/result‑effective‑variable fight (In re Antonie). This is the claim most likely to survive an obviousness challenge as currently evidenced.
• No secondary considerations on the record: The patent lapsed in 2011 for non‑payment of maintenance (see the Legal Events in the prior section), and I found no evidence of commercial success, licensing, copying, or unexpected results tied to these claims. Absent nexus evidence, the Graham secondary factors do not cut against the rejection.

8. Bottom line

• Claim 1 is the most vulnerable independent claim, and the vulnerability is concentrated in two narrow limitations (backup seat carried by the lever arm; backup valve downstream of the throttling valve). A rejection built on US 5,719,609 with KSR rationales (A)–(D) above, plus a secondary reference, declaration testimony on the routine nature of lever‑carried dual sealing, and US 5,751,319 for the conduit/housing/‑1″‑water teachings, is a defensible § 103 position.
• Claims 2, 4, 5, 6, 7 are the most obvious — they recite the conduit/housing, the functionally dictated spacing, and, critically, both mirror‑image seat positions (6 and 7), which is powerful evidence of non‑critical design choice.
• Claim 8 is obvious under the overlapping/adjacent‑range doctrine, given '609's ‑2″/‑10″ band and '319's ~1″ water leak‑prevention pressure.
• Claim 3 (shared seat) is the technical heart and the most contestable; claim 9 (0.005″–0.030″) is unsupported by the retrieved art and would need additional evidence.
• Caveat that changes everything: before relying on US 5,719,609 in a § 103 combination, resolve the common‑ownership/§ 103(c) question described in § 7. If '609 is disqualified, the remaining two references of record ('319 and '585,111) do not teach the two‑valve lever architecture, and the obviousness case would need new art.

9. What I could not verify (stated explicitly rather than assumed)

1. The full text of apparatus claim 1 of US 5,719,609. I retrieved its abstract, extensive specification passages, and method claim 8/9 text, but not the exact wording of its apparatus claim 1. The disclosure mapping in § 2.1 is from the specification, which is the proper basis for § 103 in any event.
2. US 5,835,111's content — not retrieved; its title and field (flex‑circuit interconnect) make it immaterial to claims 1–9, but I did not confirm this by reading it.
3. Whether the '353 file history contains an actual § 102(e)/§ 103 rejection over '609 — not retrieved.
4. The date‑dependent applicability of 35 U.S.C. § 103(c) to a 1996‑filed application — I believe it depends on the statutory version in effect but have not verified it; do not treat my statement as a legal conclusion.
5. Any 2026 litigation/PTAB activity specific to US 5,923,353 — consistent with the prior section, none was found. For completeness of the record I note that a different, unrelated patent naming Pawlowski, Jr. (US 5,777,647) appears as prior art in IPR2020‑01084, HP Inc. v. Slingshot Printing LLC, but that proceeding does not involve US 5,923,353, and I did not verify US 5,777,647's filing date or content, so I have not relied on it here.

This is a technical obviousness assessment based on retrieved documents, not a legal opinion; claim construction, § 102(e) dating, and the § 103(c) threshold issue should be confirmed by counsel.