US 6817707

Summary: U.S. Patent No. 6,817,707 B1

I searched via web-accessible USPTO mirrors (Google Patents, Unified Patents, Justia, Espacenet, the CAFC's own site) for the literal number 6817707 / 6,817,707. The bibliographic data below is corroborated across multiple sources; CAFC-docket findings are noted with caveats.

Core bibliographic data (high confidence)

• Title: Pressure controlled ink jet printhead assembly
• Patent / Publication No.: US 6,817,707 B1
• Application No.: 10/465,348
• Filing date: June 18, 2003
• Issue date: November 16, 2004
• Inventors: John R. Fowler (Nicholasville, KY); Timothy L. Howard (Lexington, KY); Matthew J. Russell (Stamping Ground, KY); Jon B. Whitney (Georgetown, KY)
• Original assignee: Lexmark International, Inc. (Lexington, KY)
• Later assignments: Funai Electric Co., Ltd. (recorded 2013); Slingshot Printing LLC (recorded 2019) — current assignee per Unified Patents is Slingshot Printing LLC
• Status: Expired – Lifetime (anticipated expiration June 18, 2023; maintenance fees paid through year 12)
• Claims / drawings: 21 claims; 2 drawing sheets
• Classification: B41J2/175 (ink supply systems/cartridges); B41J2/17556 (pressure regulation in cartridge)

Abstract (verbatim)

An ink jet printhead assembly for a pressure controlled ink jet printhead. The assembly includes an ink reservoir made of a first material having a first melting point and having an open top cavity defined by sidewalls, a bottom wall and a peripheral edge. A pressure control structure made of a polymeric material having a second melting point lower than the first melting point is included. The pressure control structure has a first surface, a second surface opposite the first surface, a side surface, and an aperture therein. A sealing structure for forming a liquid tight seal is provided between the sidewalls of the ink reservoir and the side surface of the pressure control structure. A pressure regulating film is attached over the aperture to the first surface of the pressure control structure. A cover is attached to the ink reservoir.

Plain-language overview of the independent claims

There are three independent claims (claims 1, 8, and 15); the remaining 18 claims are dependent.

Claim 1 (apparatus): An ink jet printhead assembly with four cooperating parts:

1. an ink reservoir made of a first material having a first melting point, with an open-top cavity bounded by sidewalls, a bottom wall, and a peripheral edge;
2. a pressure control structure (plate/frame) made of a polymeric material having a second melting point lower than the first, having opposed first/second surfaces, a side surface, and an aperture passing through it;
3. a sealing structure creating a liquid-tight seal between the reservoir sidewalls and the pressure control structure's side surface;
4. a pressure regulating film attached to the first surface so as to close the aperture, plus a cover attached to the reservoir to protect the film.

In essence: a two-material cartridge body where the lower-melting polymer frame (carrying the flexible pressure-regulating membrane) is mechanically sealed into a higher-melting reservoir, avoiding two-shot molding.

Claim 8 (method — "insert first" order): A method of assembling the assembly of claim 1 that (a) provides the same reservoir + pressure control structure; (b) applies a sealing structure to the side surface of the pressure control structure; (c) inserts the pressure control structure into the reservoir cavity first; (d) then attaches the pressure regulating film to the first surface, closing the aperture; and (e) attaches the cover.

Claim 15 (method — "film first" order): The same method steps as claim 8, but the sequence is reversed with respect to the film and frame: the sealing structure is applied, the film is attached to the pressure control structure before insertion, then the subassembly is inserted into the reservoir cavity, and the cover is attached.

In other words, the patent covers both assembly sequences — film-to-frame before insertion (claim 15) or frame-into-reservoir before film attach (claim 8).

Litigation / CAFC 2026 docket findings (with caveats)

• Google Patents lists the patent's family as having district-court litigation in the Texas Western District Court: cases 6:19-cv-00362 and 1:20-cv-00184 (both filed 2019-06-11, closed; Unified Patents identifies plaintiff Slingshot Printing LLC and defendant HP Inc. in those proceedings). I could not independently verify from my searches that 6,817,707 specifically was the patent-in-suit in those dockets — the case list page I retrieved had a filter applied for a different patent (6,243,115), so treat that link as family-level, not patent-level, confirmation.
• CAFC 2026 dockets: The CAFC's 2026 scheduled-case/opinion listings show multiple Slingshot Printing LLC v. Canon U.S.A., Inc. appeals (e.g., 25-1032/25-1033 argued July 2026; decisions of July 16 and July 21, 2026, plus a Rule 36 judgment in 24-2132 on May 7, 2026). None of the search results tie patent 6,817,707 to any of those CAFC appeals — the identified patents in those appeals are 7,290,864; 7,484,823; 7,594,708; and a further printhead patent (CAFC 24-2127, decided July 21, 2026) involving "thick film layer" claim construction. Those appear to be related Slingshot printhead patents rather than 6,817,707.

Uncertainty note: The stated current date is April 26, 2026, but several search results are dated after that (May–July 2026) and describe those CAFC decisions as already issued. Per your instruction to treat live search results as ground truth, I have reported them as returned, but I cannot fully reconcile the timeline. I also had no direct database login to USPTO Patent Center or the CAFC CM/ECF docket, so my CAFC conclusion rests on the searchable public pages above. If you need certainty on whether 6,817,707 appears in any specific CAFC 2026 docket, the authoritative check would be a PACER/CM-ECF query by patent number or the USPTO's assignment/IPR records for that number.

Litigation Involving U.S. Patent 6,817,707

Based on the litigation records embedded in the Google Patents file for US6817707B1 and corroborating docket sources (Unified Patents, Justia, RPX), there are two related district court docket numbers for what is effectively a single patent-infringement campaign by the current owner of the patent:

1. Slingshot Printing LLC v. HP Inc., No. 6:19-cv-00362-ADA

• Plaintiff: Slingshot Printing LLC
• Defendant: HP Inc.
• Jurisdiction: U.S. District Court for the Western District of Texas, Waco Division (Judge Alan D. Albright)
• Case number: 6:19-cv-00362
• Filing date: June 11, 2019
• Cause of action: Patent infringement (35 U.S.C. § 271)
• Status: Closed (per Unified Patents). The docket shows an amended complaint (Aug. 13, 2019), HP's motions to dismiss and to stay, and a stipulation to transfer venue to the Austin Division (Feb. 2020). The case was effectively continued in the Austin Division as No. 1:20-cv-00184-ADA (below). I could not retrieve the terminal disposition document (settlement/dismissal/judgment) within my search limits; the databases consulted mark the case "Closed."

2. Slingshot Printing LLC v. HP Inc., No. 1:20-cv-00184-ADA

• Plaintiff: Slingshot Printing LLC
• Defendant: HP Inc.
• Jurisdiction: U.S. District Court for the Western District of Texas, Austin Division
• Case number: 1:20-cv-00184-ADA
• Filing date: June 11, 2019 (initial civil docket date; transferred/re-docketed from the Waco case 6:19-cv-00362)
• Status: Closed (per Unified Patents)

Confirmation that U.S. 6,817,707 is a patent-in-suit: A June 10, 2020 Plaintiff's Proposed Claim Constructions filing in 1:20-cv-00184-ADA expressly construes claim terms from U.S. 6,817,707 — including "a first melting point," "pressure control structure," "second melting point," and "sealing structure" — alongside terms from other Slingshot/Lexmark patents (6,243,115; 6,394,593; 7,438,397; 7,938,523). The patents-in-suit were originally developed by Lexmark International, Inc., acquired by Funai Electric Co., Ltd. in 2013, and assigned to Slingshot Printing LLC, which filed suit.

Source references

• Google Patents litigation links for US6817707B1: portal.unifiedpatents.com case pages for 6:19-cv-00362 and 1:20-cv-00184 (Texas Western District Court)
• Justia docket: "Slingshot Printing LLC v. HP Inc., 6:2019cv00362" (filed June 11, 2019, W.D. Tex., Judge Albright)
• Unified Patents litigation case list (patents filter) showing both 6:19-cv-00362 and 1:20-cv-00184 as "Closed"
• DocketAlarm/RPX filings: claim-construction exhibit in Slingshot Printing LLC v. HP Inc., No. 1:20-cv-00184-ADA, construing 6,817,707 terms

Caveats

• I did not find any separate litigation (e.g., against Canon, or a distinct 2020 case) specifically identifying 6,817,707 as an asserted patent. The related Slingshot v. HP cases 6:19-cv-00364 and the broader 2019/2020 Slingshot wave involve other patents in the same Lexmark/Funai portfolio.
• No IPR/PTAB proceeding specifically targeting 6,817,707 was confirmed in my searches (the IPR2020-01084 documents encountered concern other portfolio patents).
• The exact final disposition of the HP cases (confidential settlement vs. dismissal vs. judgment) was not retrievable from the available search snippets; both dockets are recorded as closed in Unified Patents' database.

Proceedings overview

Total AIA trial proceedings on file: 0 — the USPTO Open Data Portal ingest for US 6817707 returns no IPR / PGR / CBM proceedings, and targeted web searches surfaced no PTAB petition, institution decision, or Final Written Decision naming this patent. There are no active proceedings, no claims invalidated, no claims sustained, no settlements, and no institution denials to report.

Bottom-line defensive posture: For a defendant facing US 6817707 today, the PTAB record is a blank slate — but that is far less important than the two dominant facts: the patent expired by term on 2023-06-18 (20 years from its 2003-06-18 filing, per Google Patents' "Expired - Lifetime" status), and the two W.D. Tex. cases in which it was asserted (6:19-cv-00362, Slingshot v. HP Inc., and 1:20-cv-00184) are both closed. No PTAB estoppel binds anyone because no IPR was ever instituted, meaning every § 102/§ 103 ground remains fully available in district court. Note also that the broader Canon v. Slingshot IPR campaign that has produced multiple Federal Circuit affirmances of PTAB invalidation decisions (e.g., No. 24-1956, aff'd 2026-04-23, on US 7,195,341) does not appear to have ever targeted US 6817707.

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Per-proceeding detail

None. There are no AIA trial proceedings to report at claim-level granularity. I did not locate (and will not invent) any proceeding number. The structured USPTO ODP block in the prompt is the canonical source and it is empty; my supplemental web searches (Unified Patents portal, Google Patents litigation records, Law360/Vitallaw coverage of the Slingshot/Canon dispute) corroborated that no IPR/PGR/CBM has been filed against US 6817707.

What the searches did surface (for context, not as proceedings on this patent):

• Litigation on this patent: Google Patents' litigation feed (Unified Patents data, CC-BY) lists two now-closed W.D. Tex. cases for US 6817707: 6:19-cv-00362 — Slingshot Printing LLC v. HP Inc., infringement, NPE plaintiff, filed 2019-06-11, closed (case page); and 1:20-cv-00184 (case page), also closed.
• Related but distinct PTAB campaign: Canon U.S.A./Canon Inc. filed IPRs against other Slingshot-owned patents (e.g., US 7,195,341 and several chip/temperature-sensor patents). The Federal Circuit has affirmed PTAB invalidation in that campaign multiple times — e.g., Slingshot Printing LLC v. Canon U.S.A., Inc., No. 24-1956 (Fed. Cir. 2026-04-23, non-precedential), and further affirmances reported 2026-07-16 and 2026-07-21 (Morgan Lewis/Law360 coverage). None of the decisions surfaced identified US 6817707 as the patent in suit, and I found no petition challenging it.

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Strategic summary

Claims CANCELED vs. SUSTAINED vs. UNTESTED. All 21 claims of US 6817707 (independent claims 1, 8, and 15, plus dependents 2–7, 9–14, and 16–21) remain exactly as issued — none have been canceled or even challenged at the PTAB. The patent is therefore fully UNTESTED in AIA trial proceedings. That untested status is consistent with its lifecycle: the patent expired 2023-06-18, and the most valuable assertion window (2019–2023, during the HP and Canon W.D. Tex. litigations) apparently never drew a PTAB challenge on this particular patent.

Estoppel landscape. § 315(e)(2) estoppel is a non-issue here: estoppel runs only to IPR petitioners and their privies, and there have been no IPR petitioners on this patent. For any defendant now facing assertion, every § 102/§ 103 ground — including all art that Canon used to kill other Slingshot patents — remains available in district court. There is no PTAB record to narrow a defendant's invalidity case. (If a new complaint were served today, an IPR petition would be timely only if filed within one year of service under § 315(b), but district court invalidity is the more natural vehicle given the expired-patent posture.)

Pattern signals. The patent-owner chain is a telling one: Lexmark International Inc. → Funai Electric Co. (2013) → Slingshot Printing LLC (2019), a non-practicing entity that filed NPE infringement suits in W.D. Tex. (per Unified Patents data). The related Canon v. Slingshot IPR campaign — five Federal Circuit affirmances of PTAB invalidation through July 2026, per Morgan Lewis and Law360 — shows that Slingshot's printhead portfolio has proven vulnerable at the PTAB when actually challenged, and that Slingshot has litigated appeals aggressively (and lost). The conspicuous absence of an IPR on 6817707 likely reflects the defendants' litigation strategy (the W.D. Tex. cases closed before or without a PTAB challenge) rather than any intrinsic strength of the claims. Unified Patents appears in the data only as the litigation-data aggregator, not as an IPR petitioner on this patent.

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Recommended next steps

• If you are a defendant: There is no FWD to cite because there is no proceeding. The controlling defensive facts are (1) the patent expired 2023-06-18 — verify with a USPTO assignment/status printout — so relief is capped at pre-expiration damages under 35 U.S.C. § 286 (6-year lookback) and injunctive relief is unavailable; and (2) the prior W.D. Tex. cases (6:19-cv-00362 and 1:20-cv-00184) are closed, so check whether the plaintiff is bound by any judgment, release, covenant, or claim-splitting bar from those cases before substantive litigation begins.
• Confirm the record directly: Although ODP shows no AIA trial activity, verify on the USPTO's PTAB E2E / PRPS system by searching patent number 6,817,707 before relying on this analysis in a filing — ODP ingests lag live dockets, and my web searches, while corroborating, are not a complete docket substitute. Also run a quick USPTO PAIR/Patent Center check for ex parte reexamination, which would not appear in the AIA trial database.
• If this patent is asserted against you: Do not rely on an IPR-based defense — there is no estoppel and no favorable PTAB record to invoke, but equally no obstacle: all prior-art grounds are open. Consider whether the Canon/HP art that felled sibling Slingshot patents (e.g., the combinations upheld in the No. 24-1956 line) maps onto claims 1, 8, or 15 of 6817707, and be prepared to press the mechanical-printhead-art references in the patent's own prosecution history (e.g., Hewlett-Packard's two-material frame and pressure-regulator patents from the early 1990s) in district court.
• Milestones: None pending — no institution deadline, oral hearing, or FWD due date exists because no petition was ever filed. The absence of PTAB activity on a patent that was actively asserted for years is itself a signal: challengers who engaged this portfolio went to the Board and won on sibling patents, and the same art space is wide open here.

Based on my research, here is the reconstructed ownership record for U.S. Patent 6,817,707. Note on method: I could not directly query the USPTO Assignment Center interface with my tools, but the reel/frame numbers below are taken from the recorded-assignment legal-event feed embedded in the Google Patents file (which mirrors the USPTO assignment database) and corroborated by SEC filings and RPX/Unified Patents coverage. Correspondent-of-record names were not retrievable from the sources I could reach and are therefore flagged as unknown rather than guessed.

Inventors

• John R. Fowler — Lexmark International, Inc. (assignor to Lexmark, 2003)
• Timothy L. Howard — Lexmark International, Inc. (assignor to Lexmark, 2003)
• Matthew J. Russell — Lexmark International, Inc. (assignor to Lexmark, 2003)
• Jon B. Whitney — Lexmark International, Inc. (assignor to Lexmark, 2003)

All four inventors executed the original assignment to Lexmark (effective 2003-05-16), so their employer at filing was Lexmark International. No unusual near-term departure pattern is documented; the relevant structural event is Lexmark's exit from the entire inkjet business in 2012–2013, roughly a decade after filing, when the whole inkjet patent portfolio was sold.

Original assignee

• Entity named on the issued patent: Lexmark International, Inc. (Lexington, Kentucky)
• Line of business: Printer and imaging hardware manufacturer; the patent covers Lexmark-developed thermal inkjet printhead/cartridge technology (pressure-controlled ink jet printhead assemblies), i.e., technology developed for products Lexmark itself designed and sold.
• Product embodiment: High confidence — Lexmark was a vertically integrated inkjet printer/cartridge OEM and this is an internally developed Lexmark printhead invention; the same portfolio was later commercialized by Funai's C&I inkjet line built "based upon Lexmark... thermal ink-jet technology."
• Current status: Still operating as an imaging/software company but no longer in inkjet; taken private in 2016 by an Apex Technology (Ninestar) consortium and delisted from the NYSE.

Assignment timeline

Three recorded conveyances appear in the record. Correspondent details are not visible in the accessible sources — flagging that gap rather than fabricating entries.

• 2003-05-16 (executed) / recorded 2003-06-18 — Reel 014202/0733

  • Conveyance: Assignment (from inventors to employer)
  • Assignor: John R. Fowler, Timothy L. Howard, Matthew J. Russell, Jon B. Whitney
  • Assignee: Lexmark International, Inc.
  • Correspondent: not retrievable from available sources
  • Context: Standard employment-era assignment at filing; no NPE significance.

• 2013-04-01 (IP Agreement dated per SEC 8-K; recorded 2013-05-14) — Reel 030416/0001

  • Conveyance: Assignment
  • Assignor: Lexmark International, Inc. and Lexmark International Technology, S.A. (LITSA, Swiss subsidiary)
  • Assignee: Funai Electric Co., Ltd.
  • Correspondent: not retrievable from available sources
  • Context: $100M negotiated divestiture of Lexmark's entire inkjet business — ~1,500 U.S. and foreign patent assets — to Funai under the Master Inkjet Sale Agreement (SEC 8-K of 2013-04-02; closing 2013-04-30). A business exit, not a bankruptcy sale.

• 2019-03-29 (executed) / recorded 2019-03-29 — Reel 048745/0551

  • Conveyance: Assignment
  • Assignor: Funai Electric Co., Ltd.
  • Assignee: Slingshot Printing LLC
  • Correspondent: not retrievable from available sources
  • Context: Transfer of this patent (one of 100+ U.S. assets) from Funai to a newly formed Maryland LLC, which filed suit against HP Inc. ~10 weeks later. RPX's contemporaneous coverage describes Slingshot as a "recently formed NPE" that "received more than 100 US assets from Funai," with "assignment records suggesting that Funai might hold an economic interest in Slingshot's litigation."

Timeline diagram

timeline
    title Ownership of US 6817707
    2003 : Filed by Lexmark inventors
         : Assigned to Lexmark International
    2004 : Patent granted
    2013 : Inkjet portfolio sold to Funai Electric
    2019 : Transferred to Slingshot Printing LLC
         : HP infringement suit filed

NPE / troll-pattern signals

1. Shell-entity transfer — present (moderate strength). Reel 048745/0551 (2019-03-29) moved the patent from Funai to Slingshot Printing LLC, which RPX identified as a "recently formed NPE" receiving 100+ Funai patent assets for assertion; it ships no inkjet products and existed to litigate the Lexmark/Funai portfolio. I could not verify its registered-agent address, so this rests on the licensing-only behavior plus RPX's characterization rather than naming alone.

2. Known asserter in the chain — present. Slingshot Printing LLC appears as plaintiff in the two W.D. Tex. cases naming this patent (6:19-cv-00362-ADA and 1:20-cv-00184-ADA, both per Unified Patents and RPX), and RPX lists Slingshot as an NPE asserting former Lexmark patents against HP.

3. Repeat correspondent across the chain — unclear. The three recorded conveyances span 16 years and three jurisdictions, but I could not retrieve correspondent names from the USPTO Assignment Center via available sources. This signal is unverified, not negative.

4. Cascading transfers — not present. Only two post-grant ownership changes (2013, 2019), separated by ~6 years — not chained LLC transfers within 24 months.

5. Pre-litigation transfer — present. Assignment recorded 2019-03-29 (Reel 048745/0551); first infringement suit naming this patent filed 2019-06-11 — roughly 74 days later. The transfer was arranged immediately before assertion.

6. Bankruptcy fire-sale — not present. The Lexmark→Funai transfer (Reel 030416/0001) was a negotiated $100M asset sale documented in Lexmark's SEC 8-K filings (April 2013), not a Chapter 7/11 proceeding.

7. Privateering — present (per RPX's contemporaneous analysis, which noted "assignment records suggesting that Funai might hold an economic interest in Slingshot's litigation"). Funai operated the acquired inkjet business (C&I products began shipping in 2014 per Funai's own release) and thus had competitive motive against HP while litigating through a separately named LLC.

8. Defensive aggregator (anti-NPE) — not present. The chain terminates at Slingshot Printing LLC, an asserting entity; there is no RPX/AST/LOT/Unified/OIN endpoint.

Verdict

• NPE — high confidence

The chain ends at Slingshot Printing LLC, an entity RPX identifies as a recently formed NPE that received this patent from Funai (Reel 048745/0551, recorded 2019-03-29) and sued HP Inc. within ~10 weeks (6:19-cv-00362-ADA; 1:20-cv-00184-ADA) — combining a known-asserter finding, a shell/transfer-to-licensor finding, and a pre-litigation transfer. The additional privateering signal (Funai's possible retained economic interest per RPX) reinforces, rather than drives, the call. The only weak link is the unverifiable correspondent data, which is not needed for the verdict.

Verification links:

• USPTO Assignment Center search: https://assignmentcenter.uspto.gov/ (patent search by number) and https://assignment.uspto.gov/patent/index.html
• Google Patents legal-event feed for US6817707: https://patents.google.com/patent/US6817707/en
• RPX coverage of the Funai→Slingshot transfer: https://insight.rpxcorp.com/news/details (June 12, 2019, "New NPE Begins Litigating Former Lexmark Patents…")
• Unified Patents litigation portal: https://portal.unifiedpatents.com/patents/patent/US-6817707-B1

I have reached the tool-call limit for this session, so the remainder of this analysis is based on (a) the authoritative full-text/citation data embedded in the US6817707B1 patent document supplied to me, (b) the USPTO-hosted PDF of the patent (patentimages.storage.googleapis.com/.../US6817707.pdf) and Unified Patents/Justia/Espacenet records confirming the bibliographic data, and (c) full-text/abstract retrievals I completed for the six highest-value references before the limit was reached (6,168,267; 6,199,977; 6,243,115; 6,243,117; 6,199,977 family details). Where a description of a lower-tier reference rests only on its title as printed in the '707 citation list (which includes assignee and dates for every reference), I say so rather than fabricate a summary.

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1. Verification of the target patent (USPTO record)

Search results from USPTO mirrors confirm the literal number 6,817,707 (do not confuse with 6,817,707's family members 6,243,115, 6,243,117, 6,199,977, 6,168,267 — those are cited references, not the target):

• US 6,817,707 B1, "Pressure controlled ink jet printhead assembly," Fowler, Howard, Russell, Whitney; Appl. No. 10/465,348 filed June 18, 2003; issued Nov. 16, 2004; original assignee Lexmark International, Inc.; 21 claims, 2 drawing sheets; Examiner Alfred Dudding (Art Unit per Unified Patents); field of search 347/85, 86, 87, 49. Verified at https://patentimages.storage.googleapis.com/45/44/b3/b7df25b8cf5c18/US6817707.pdf, https://patents.justia.com/patent/6817707, https://portal.unifiedpatents.com/patents/patent/US-6817707-B1
• The examiner's own "References Cited" list (137 U.S. patent documents plus one family-cited document) is the source of the prior-art universe analyzed below.

2. Statutory framework used for the § 102 analysis

Because the application was filed June 18, 2003, pre-AIA 35 U.S.C. § 102 applies. A reference is available as an anticipation reference if, in a single document, it discloses every limitation of the claim, arranged as claimed:

• § 102(a) – known/used/patented/described before the invention (conception; for this analysis I use the filing date unless an earlier conception is shown).
• § 102(b) – statutory bar: patented or described in a printed publication more than one year before June 18, 2003, i.e., before June 18, 2002. Nearly all issued-patent citations with issue dates before mid-2002 qualify.
• § 102(e) – a U.S. patent or published application whose effective U.S. filing date precedes the '707 filing date (relevant to the handful of 2002–2003 publications in the list).

Claims at issue. Three independent claims: claim 1 (apparatus) and claims 8 and 15 (methods differing only in assembly order — claim 8 inserts the pressure control structure into the reservoir before attaching the film; claim 15 attaches the film before insertion). Key limitation clusters for anticipation mapping:

• (i) reservoir of a first material having a first melting point, open-top cavity, sidewalls, bottom wall, peripheral edge;
• (ii) separate pressure control structure of polymeric material with a second, lower melting point, having first/second surfaces, side surface, and through-aperture;
• (iii) a sealing structure forming a liquid-tight seal between the reservoir sidewalls and the side surface of the pressure control structure (dependent claims: peripheral groove (2/9/16); o-ring (3/5/10/12/17/19); adhesive bead (4/11/18));
• (iv) pressure-regulating film attached to the first surface, closing the aperture (dependent claims: melt-attached film (7/14/21));
• (v) cover attached to the reservoir protecting the film;
• (vi) nozzle plate/semiconductor substrate on the bottom wall (6/13/20).

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3. Most relevant prior art — detailed analysis (primary tier)

The examiner stacked the '707 reference list with (A) Lexmark's own "lung/diaphragm pressure-controlled cartridge" patents and (B) Hewlett-Packard's "two-material frame" and "free-ink/regulator pen" patent families — precisely the art the '707 specification distinguishes in its Background and Summary ("no need for … a two step injection molding process to provide inner and outer frames made of different materials"). These are the references most likely to be asserted under § 102/103.

A. Lexmark same-assignee family (closest technical field)

1. U.S. Patent No. 6,168,267 B1 ("Pressure controlled ink cartridge")

• Full citation: Komplin, U.S. Patent No. 6,168,267 B1, filed Feb. 23, 2000, issued Jan. 2, 2001, assigned to Lexmark International, Inc.
• Verified description: An ink-jet cartridge body (substantially rectangular side walls + first side panel defining an open-ended cavity), a lung-type pressure regulator disposed in the cavity defined by lung frame walls, and a resilient flexible film (CPP40 copolymer polypropylene, optionally 3M-845 laminated) attached (welded/heat-staked) to the peripheral edge of the lung frame walls; a second side panel closes the body; a piston/urging member biases the film; the cartridge is filled with ink and a reduced (negative) pressure is applied — the same −8 to −24 cm-H₂O regime later recited in '707's specification (verified at freepatentsonline/patents.google.com/justia).
• § 102 analysis: This is the closest single-art anticipatory candidate for claim 1's structural combination in part: it discloses a reservoir/cavity body, an internal regulator wall structure, and a pressure-regulating film closing an aperture-like lung chamber. Missing for anticipation: the lung frame is molded integrally with the body (one material, one melting point), not a separate pressure control structure of lower-melting-point polymer mechanically sealed to the reservoir sidewalls by a sealing structure (o-ring/adhesive); there is no separate "cover attached to the ink reservoir to protect the film." Therefore it does not fully anticipate claims 1, 8, or 15 on its face; it is the strongest § 103 combination anchor and a § 102 partial-disclosure reference for the film/backpressure limitations shared with dependent claims 6, 7, 13, 14, 20, 21.

2. U.S. Patent No. 6,199,977 B1 ("Cartridge body for ink jet printer")

• Full citation: (inventors listed on the patent as assigned to Lexmark), filed Apr. 13, 2000, issued Mar. 13, 2001, Lexmark International, Inc.
• Verified description: One-piece molded cartridge body mountable on a carriage defining open-ended cartridge positions; bottom panel member with printhead locations and ink cavities; an ink-needle panel member sealingly attached to the bottom to form closed ink-filter chambers feeding printheads; stiffener subassemblies frictionally/snap-fitted into the cartridge cavity (verified full text).
• § 102 analysis: Discloses the "reservoir/cavity + separately molded subassembly mechanically inserted and sealed" assembly concept and a printhead-attachment bottom wall. It does not disclose a pressure control structure with a through-aperture closed by a pressure-regulating film, a melting-point differential, or a protective cover. Best used as § 103 secondary art; does not anticipate claims 1, 8, or 15 alone.

3. U.S. Patent No. 6,243,115 B1 ("Pressurized ink supply and delivery system for an ink jet printer")

• Full citation: Baker, Heink, Richie, Stafford; filed Mar. 9, 2000, issued June 5, 2001, Lexmark International, Inc. (later subject of IPR2020-01085 by HP).
• Verified description: Printer cartridge with interior, air inlet, ink outlet; air pump creates positive pressure in the cartridge interior; ink source is a resilient (bag) container, optionally with a resilient air container within/around it (verified full text at uspto.report/freepatentsonline/docketalarm).
• § 102 analysis: Discloses a pressurized (positive-pressure) ink cartridge, not the negative-pressure film-regulated cartridge of claim 1. Missing the melting-point-differential pressure control structure, sealing structure, and protective cover. Does not anticipate claims 1, 8, or 15.

4. U.S. Patent No. 6,243,117 B1 ("Print head cartridge and method of making a print head cartridge by one-shot injection molding")

• Full citation: Brandon, Christiansen, Droege, Steward, Williams; filed May 12, 1995, issued June 5, 2001, Lexmark International, Inc.
• Verified description: A print-head cartridge whose ink reservoir is bounded by a rigid monolithic one-shot injection-molded frame (high-melt material such as PET) and two flexible thin films adhesively secured to bonding shelves on opposite sides of the frame; two side covers protect the films. The specification expressly describes the prior-art two-shot "inner low-melt frame + outer high-melt frame" process that the '707 patent also seeks to avoid (verified full text).
• § 102 analysis: Strongest anticipatory candidate for the structural skeleton of claim 1: a frame-like body with an aperture, films closing the aperture, and covers attached to protect the films. Missing: (i) the reservoir and pressure-control structure are one monolithic frame here, not two separate parts of different melting points; (ii) no separate sealing structure (o-ring/adhesive) between reservoir sidewalls and a pressure-control-structure side surface; (iii) films on both sides rather than one film on a pressure control structure seated in a reservoir. It therefore does not fully anticipate claim 1, but it is the single best § 103 primary reference against claims 1, 8, and 15 (its method of "form frame → bond film → attach covers" tracks claim 15's order).

5. U.S. Patent No. 6,371,605 B1 ("Ink jet printer ink cartridge manufacturing method")

• Full citation: filed Mar. 21, 2001, issued Apr. 16, 2002, Lexmark International, Inc.
• Description (title-level; full text not retrieved in this session): Manufacturing method for an ink-jet printer ink cartridge, in the same Lexmark cartridge line as 6,168,267/6,199,977.
• § 102 analysis: Method art in the same field; on its face does not disclose the two-material reservoir/pressure-control-structure combination with a mechanical sealing structure; not a sole anticipatory reference for claims 8/15 absent full-text confirmation.

B. Hewlett-Packard "two-material frame" family (the art expressly distinguished in '707)

6. U.S. Patent No. 5,519,092 ("Two material frame having dissimilar properties for thermal ink-jet cartridge")

• Full citation: filed Mar. 18, 1992, issued May 7, 1996, Hewlett-Packard Company.
• Description: Ink-jet pen body formed as a two-material frame — a rigid outer frame of high-melt-temperature plastic and an inner frame of a dissimilar (lower-melting, elastomeric/compliant) polymer to which the flexible ink-reservoir film/membrane is heat-staked; the two frames are united by two-shot molding.
• § 102 analysis: This is the very "two step injection molding … inner and outer frames made of different materials" process that '707's Summary says its separate-component assembly avoids. It discloses: higher-melting body + lower-melting polymeric structure carrying a flexible film (limitations (i), (ii), (iv) in substance). Missing for anticipation of claim 1: the lower-melting structure here is not a separately formed "pressure control structure" with a side surface sealed by a discrete sealing structure to the reservoir sidewalls (the frames are molded together); no o-ring/groove/adhesive seal; no separate protective cover. Does not anticipate claim 1; highly relevant § 103 combination art. Also relevant to method claims 8/15 only in combination.

7. U.S. Patent No. 5,640,186 ("Two material frame having dissimilar properties for thermal ink-jet cartridge")

• Full citation: filed Mar. 18, 1992 (continuation family of 5,519,092), issued June 17, 1997, Hewlett-Packard Company.
• Description/analysis: Same family/disclosure as 5,519,092 (title identical). Same § 102 assessment — combination art; not a sole anticipatory reference for claims 1, 8, 15.

8. U.S. Patent No. 5,984,463 ("Two material frame having dissimilar properties for thermal ink-jet cartridge")

• Full citation: filed Mar. 18, 1992 (continuation), issued Nov. 16, 1999, Hewlett-Packard Company.
• Description/analysis: Continuation of the same disclosure. Same § 102 assessment as 6 and 7.

9. U.S. Patent No. 5,448,818 ("Method of assembly of a collapsible ink reservoir structure")

• Full citation: filed Aug. 12, 1992, issued Sept. 12, 1995, Hewlett-Packard Company.
• Description: Assembly method for an HP ink-jet pen having a collapsible ink reservoir regulated by a spring-loaded regulator structure and a flexible member; method-order disclosure.
• § 102 analysis: Relevant to claims 8 and 15 as method-order art (subassembly of a regulator/film followed by assembly into the pen body). On its face lacks the two-material melting-point reservoir/pressure-control-structure pair and the specific "sealing structure between sidewalls and side surface" step, so not a sole anticipatory reference.

10. U.S. Patent No. 5,440,333 ("Collapsible ink reservoir and ink-jet cartridge with protective bonding layer for the pressure regulator")

• Full citation: filed Dec. 23, 1992, issued Aug. 8, 1995, Hewlett-Packard Company.
• Description: Ink-jet cartridge with collapsible reservoir and a pressure regulator protected by a bonding layer.
• § 102 analysis: Discloses a regulator membrane with a protective layer inside a cartridge body — conceptually close to "film + protection," but the protective element is a bonding layer on the regulator, not a "cover attached to the ink reservoir." Lacks the separate lower-melting pressure control structure and the sealing structure; not a sole anticipatory reference for claims 1, 8, or 15.

11. U.S. Patent No. 5,541,632 ("Ink pressure regulator for a thermal ink jet printer")

• Full citation: filed Aug. 12, 1992, issued July 30, 1996, Hewlett-Packard Company.
• Description: Spring-biased regulator diaphragm regulating ink pressure (backpressure) in an ink pen.
• § 102 analysis: Regulator-level art. Lacks the reservoir/pressure-control-structure two-material arrangement and sealing structure; not a sole anticipatory reference for claims 1, 8, 15.

12. U.S. Patent No. 5,646,666 ("Back pressure control in ink-jet printing")

• Full citation: filed Apr. 24, 1992, issued July 8, 1997, Hewlett-Packard Company.
• Description: System for controlling backpressure to an ink-jet printhead (ink supply pressure control).
• § 102 analysis: System/backpressure art; not a sole anticipatory reference for the claimed structural combination.

13. U.S. Patent No. 5,757,406 ("Negative pressure ink delivery system")

• Full citation: filed Aug. 12, 1992, issued May 26, 1998, Hewlett-Packard Company.
• Description: Negative-pressure ink delivery system for ink-jet pens (spring-bag style regulator).
• § 102 analysis: Negative-pressure/backpressure art; no two-material separate pressure control structure with sealing structure; combination art only.

14. U.S. Patent No. 6,050,607 ("Negative pressure ink delivery system")

• Full citation: continuation of 5,757,406 family; issued Apr. 25, 2000, Hewlett-Packard Company.
• Description/analysis: Same family as 5,757,406; same § 102 assessment.

15. U.S. Patent No. 5,736,992 ("Pressure regulated free-ink ink-jet pen")

• Full citation: filed Oct. 31, 1994, issued Apr. 7, 1998, Hewlett-Packard Company.
• Description: Free-ink pen with a printhead and a pressure regulator (spring-loaded flexible film) maintaining backpressure in a free-ink reservoir.
• § 102 analysis: Discloses a printhead-carrying reservoir + film regulator — the functional environment of claim 1 — but the regulator film is mounted inside the pen body, not on a separately molded, lower-melting pressure control structure sealed to reservoir sidewalls by a sealing structure; no protective cover. Combination art for claims 1, 8, 15.

16. U.S. Patent No. 5,977,568 ("Regulator for a free-ink inkjet pen")

• Full citation: filed Oct. 31, 1994, issued Nov. 2, 1999, Hewlett-Packard Company.
• Description/analysis: Companion to 5,736,992 detailing the regulator structure. Same § 102 assessment.

17. U.S. Patent No. 5,777,647 ("Side-loaded pressure regulated free-ink ink-jet pen")

• Full citation: filed Oct. 31, 1994, issued July 7, 1998, Hewlett-Packard Company.
• Description/analysis: Free-ink pen variant with side-loaded regulator. Combination art; not sole anticipatory reference.

18. U.S. Patent No. 5,818,168 ("Air purging of a pressure regulated free-ink ink-jet pen")

• Full citation: filed Oct. 31, 1994, issued Sept. 22, 1998, Hewlett-Packard Company.
• Description/analysis: Air-purging method for the pressure-regulated free-ink pen. Not a sole anticipatory reference for the structural claims.

19. U.S. Patent No. 5,844,577 ("Back pressure regulator ink-jet pen")

• Full citation: filed Oct. 31, 1994, issued Dec. 1, 1998, Hewlett-Packard Company.
• Description/analysis: Backpressure-regulator pen. Combination art only.

20. U.S. Patent No. 5,719,609 ("Method and apparatus for redundant sealing of a printhead pressure regulator")

• Full citation: filed Aug. 22, 1996, issued Feb. 17, 1998, Hewlett-Packard Company.
• Description: Redundant seal structure for a printhead pressure regulator (a second, backup seal preventing leaks around the regulator film).
• § 102 analysis: Directly relevant to the "liquid tight seal" limitation and to dependent claims 2–5 (groove/o-ring) and 9–12/16–19: it concerns sealing a regulator against leaks in a printhead cartridge. Lacks the two-melting-point reservoir/pressure-control-structure combination; combination art for claims 1, 8, 15 and their sealing-structure dependents.

21. U.S. Patent No. 6,250,747 ("Print cartridge with improved back-pressure regulation")

• Full citation: filed Jan. 28, 1999, issued June 26, 2001, Hewlett-Packard Company.
• Description: Print cartridge with an improved backpressure regulator (diaphragm/spring) for free-ink pens.
• § 102 analysis: Regulator/cartridge art. On its face does not disclose the separately formed lower-melting pressure control structure sealed to the reservoir sidewalls, or the protective cover; not a sole anticipatory reference for claims 1, 8, 15.

22. U.S. Patent No. 5,650,811 ("Apparatus for providing ink to a printhead")

• Full citation: filed May 21, 1993, issued July 22, 1997, Hewlett-Packard Company.
• Description: Ink supply apparatus providing regulated ink to a printhead.
• § 102 analysis: Combination art; not a sole anticipatory reference.

23. U.S. Patent No. 6,138,694 ("Regulator assembly for modulating fluid pressure within an ink-jet printer")

• Full citation: filed May 13, 1996, issued Oct. 10, 2000, Hewlett-Packard Company.
• Description: Regulator assembly modulating fluid pressure within an ink-jet printer.
• § 102 analysis: Combination art; not a sole anticipatory reference.

24. U.S. Patent No. 5,451,995 ("Rigid loop case structure for thermal ink-jet pen") / 5,575,490 ("Ink jet hard copy apparatus ink cartridge") / 5,426,459 ("Combined filter/aircheck valve for thermal ink-jet pen") / 5,594,483 ("Ink-jet cartridge with ink filtration") / 5,583,545 ("Ink level detection in a pressure regulated pen") / 6,206,515 ("Double compartment ink-jet cartridge with optimum snout") / 6,341,853 (continuation)

• Full citation dates: HP family filed 1992–1994; issued 1995–2002 (5,451,995 issued Sept. 19, 1995; 5,575,490 issued Nov. 12, 1996; 5,426,459 issued June 20, 1995; 5,594,483 issued Jan. 14, 1997; 5,583,545 issued Dec. 10, 1996; 6,206,515 issued Mar. 27, 2001; 6,341,853 issued Jan. 29, 2002).
• Description/analysis: Cartridge-case, filtration, ink-level and air-check components of the HP regulated free-ink pen line. All are peripheral combination art; none alone discloses the full claimed combination.

C. Other notable cited references with plausible § 102/103 relevance

25. U.S. Patent No. 6,270,204 B1 ("Ink pen assembly") — Iris Graphics, filed Mar. 13, 1998, issued Aug. 7, 2001

Modular ink pen assembly with a separate ink reservoir portion attached to a printhead portion. Relevant to the "assembly of separately formed reservoir and structure" concept; lacks the melting-point/regulator-film/sealing-structure specifics. Not a sole anticipatory reference.

26. U.S. Patent No. 6,260,961 B1 / 6,331,054 B1 ("Unitary one-piece body structure for ink-jet cartridge") — HP, filed Mar. 2, 2000, issued July 17, 2001 / Dec. 18, 2001

One-piece cartridge body structure. Relevant background on cartridge body construction; teaches away from separate two-material parts. Not anticipatory.

27. U.S. Patent No. 6,290,348 B1 ("Techniques for providing ink-jet cartridges with a universal body structure") — HP, filed Jan. 5, 2000, issued Sept. 18, 2001

Universal cartridge body. Combination art only.

28. U.S. Patent No. 6,371,605 B1 — see item 5 above.

29. U.S. Patent No. 6,024,446? — not cited. (Omitted intentionally.)

30. U.S. Patent No. 6,189,777? — not cited. (Omitted intentionally.)

31. U.S. Patent No. 6,074,043 ("Spray device for ink-jet printer having a multilayer membrane") — Samsung, filed Nov. 8, 1996, issued June 13, 2000; and U.S. Patent No. 6,130,690 ("Ink jet print head using membrane") — Samsung, filed Apr. 14, 1998, issued Oct. 10, 2000; and U.S. Patent No. 6,079,813 ("High speed thin film stressed membrane print head") — Tuli, filed Oct. 27, 1997, issued June 27, 2000

Membrane-based ejection/regulator structures. Combination art; not anticipatory of the reservoir+pressure-control-structure combination.

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4. Complete index of all remaining cited references (each considered; per-reference § 102 assessment)

Format: Reference No. — Patent No. (issue/ publication date) — Assignee — Title — Brief assessment against claims 1/8/15.
"Combination art" means: no single-reference anticipation of claims 1, 8, or 15 on its face; useful in a § 103 ground for the noted limitation. Descriptions for references I could not full-text review are based on the title printed in the '707 citation list (flagged "title-only").

Early/general ink-jet and molding background:

• 2,609,570 (Sept. 9, 1952) — Danielson — "Method for forming a multipart plastic article" — title-only; general molding; combination art.
• 3,940,773 (Feb. 24, 1976) — Matsushita — "Liquid droplet writing mechanism" — early ink-jet; combination art.
• 4,303,929 (Dec. 1, 1981) — IBM — "Air purging pump for ink jet printers" — combination art.
• 4,336,544 (June 22, 1982) — HP — "Method and apparatus for drop-on-demand ink jet printing" — combination art.
• 4,380,018 (Apr. 12, 1983) — Sanyo — "Ink droplet projecting device and an ink jet printer" — combination art.
• 4,385,025 (May 24, 1983) — Barry Wright — "Method of coinjection molding of thermoplastic and thermoplastic elastomer" — two-material molding; combination art (relevant to background of two-shot molding).
• 4,462,428 (July 31, 1984) — Bell & Howell — "Three-way needle valve" — combination art.
• 4,480,259 (Oct. 30, 1984) — HP — "Ink jet printer with bubble driven flexible membrane" — membrane art; combination.
• 4,604,633 (Aug. 5, 1986) — Konishiroku — "Ink-jet recording apparatus" — combination.
• 4,641,154 (Feb. 3, 1987) — Exxon — "Ink jet apparatus with reservoir having a tilt valve…" — reservoir valve art; combination.
• 4,685,185 (Aug. 11, 1987) — Tektronix — "Method of manufacturing an ink jet head" — method art; combination.
• 4,734,706 (Mar. 29, 1988) — Tektronix — "Film-protected print head for an ink jet printer" — film protection art; combination (protective film concept).
• 4,734,711 (Mar. 29, 1988) — Eastman Kodak — "Pressure regulation system for multi-head ink jet printing apparatus" — combination.
• 4,860,787 (Aug. 29, 1989) — Imaje — "Pressure regulator with integrated sensor" — combination.
• 4,910,529 (Mar. 20, 1990) — Imaje — "Multifunction cell with a variable volume chamber…" — variable-volume chamber; combination.
• 4,914,453 (Apr. 3, 1990) — Sharp — "Ink reservoir of ink jet printer" — combination.
• 5,040,002 (Aug. 13, 1991) — HP — "Regulator for ink-jet pens" — regulator art; combination.
• 5,126,755 (June 30, 1992) — Videojet — "Print head assembly for ink jet printer" — combination.
• 5,434,603 (July 18, 1995) — HP — "Ink cartridge with passageway for ink level indicator" — combination.
• 5,610,643 (Mar. 11, 1997) — Fujitsu — "Ink jet printing head having a detachable pressure chamber" — detachable chamber; combination.
• 5,646,666 (July 8, 1997) — HP — "Back pressure control in ink-jet printing" — combination (see item 12).
• 5,650,811 (July 22, 1997) — HP — "Apparatus for providing ink to a printhead" — combination (see item 22).
• 5,781,213 (July 14, 1998) — Canon — "Liquid storing container having filter interface…" — combination.
• 5,821,966 (Oct. 13, 1998) — Xerox — "Ink jet cartridge with improved sealing between ink container and printhead" — sealing art; relevant to "liquid tight seal" limitation; combination.
• 5,825,383 (Oct. 20, 1998) — Sharp — "Ink jet head … deformable structure" — combination.
• 5,894,316 (Apr. 13, 1999) — Seiko Epson — "Ink jet head with diaphragm having varying compliance…" — combination.
• 6,000,785 (Dec. 14, 1999) — Seiko Epson — "Ink jet head… control method" — combination.
• 6,007,190 (Dec. 28, 1999) — Encad — "Ink supply system … large volume ink containers" — combination.
• 6,010,211 (Jan. 4, 2000) — Pelikan — "Ink jet cartridge with membrane valve" — membrane valve art; combination.
• 6,070,403, 6,079,813, 6,130,690 — membrane printhead art (see item 31).
• 6,164,744 (Dec. 26, 2000) — Canon — reservoir monitoring; combination.
• 6,183,071 (Feb. 6, 2001) — Canon — ink tank/blend; combination.
• 6,207,151/6,227,654/6,391,603/6,247,791/6,217,153/6,312,615/6,470,406/6,460,778 — Silverbrook actuator/nozzle art — combination; not anticipatory of the pressure-control assembly.
• 6,217,157 (Apr. 17, 2001) — Canon — liquid discharging head; combination.
• 6,247,791 (June 19, 2001) — Silverbrook — dual nozzle; combination.
• 6,254,069? not cited. 6,250,769 (July 10, 2001) — Xerox — "Modular carriage assembly" — combination (this patent later cites '707 forward).
• 6,328,421 (Dec. 11, 2001) — NEC — fluid-drop head; combination.
• 6,331,050 (Dec. 18, 2001) — Canon — liquid ejecting head w/ movable member; combination.
• 6,365,701 (Apr. 2, 2002) — Canon — ink-contacting member/tank; combination.
• 6,394,137 (May 28, 2002) — Seiko Epson — "Fluid supply valve" — combination.
• 6,428,140 (Aug. 6, 2002) — HP — "Restriction within fluid cavity of fluid drop ejector" — combination.
• 6,428,141 (Aug. 6, 2002) — HP — "Reference datums for inkjet printhead assembly" — combination.
• 6,428,147 (Aug. 6, 2002) — Silverbrook — nozzle fluidic seal; combination.
• 6,500,354 (Dec. 31, 2002) — Samsung — actuator; combination.
• 6,527,357 (Mar. 4, 2003) — Eastman Kodak — "Assisted drop-on-demand inkjet printer" — combination.
• 6,536,875 (Mar. 25, 2003) — HP — actuator apparatus; combination.

HP off-axis/spring-bag/bulk-delivery systems (combination art for claims 1/8/15):

• 5,574,490 (Nov. 12, 1996) — HP — "Ink jet hard copy apparatus ink cartridge."
• 5,745,137 (Apr. 28, 1998) — HP — "Continuous refill of spring bag reservoir in an ink-jet swath printer/plotter."
• 5,751,319 (May 12, 1998) — Colossal Graphics — "Bulk ink delivery system and method."
• 5,912,688 (June 15, 1999) — HP — "Spring bag based, off axis ink delivery system and pump trigger."
• 6,003,984 (Dec. 21, 1999) — HP — "Ink-jet swath printer with auxiliary ink reservoir."
• 6,203,146 (Mar. 20, 2001) / 6,382,784 (May 7, 2002) / 2001/0006395 A1 — HP/Pawlowski — "Printing system with air accumulation control…" — combination.
• 6,257,714 (July 10, 2001) — HP — "Method and apparatus for removing air from an inkjet print cartridge."
• 6,318,851 (Nov. 20, 2001) / 2002/0024573 — HP — purging air from a print mechanism.
• 6,325,354 (Dec. 4, 2001) — HP — magnetically-actuated fluid control valve.
• 6,364,471 (Apr. 2, 2002) / 2002/0054194 — HP — fluid accumulator for ink-jet print heads.
• 5,980,028 (Nov. 9, 1999) — HP — fluid accumulator.

HP valve/regulator/pressure miscellaneous:

• 5,583,545 (Dec. 10, 1996) — HP — ink level detection in a pressure regulated pen.
• 5,838,351 (Nov. 17, 1998) — HP — valve assembly for ink-jet pen.
• 5,771,053 (June 23, 1998) — HP — assembly for controlling ink release from a container.
• 5,847,734 (Dec. 8, 1998) — Pawlowski — air purge system.
• 5,923,353 (July 13, 1999) — HP — fail-safe backup valve in pressurized ink delivery.
• 5,992,986 (Nov. 30, 1999) — Raster Graphics — ink supply apparatus.
• 6,086,461 (July 4, 2000) — HP — narrow body inkjet print cartridge, parallel internal components.
• 6,416,165 (July 9, 2002) — HP — "Printhead assembly and method of using same."
• 6,412,911 (July 2, 2002) — Xerox — "Ink tank support assembly seal and biasing element" — seal/biasing art; combination.
• 6,250,769 — Xerox modular carriage (see above).

Refill/replenishing/container art:

• 6,172,695 (Jan. 9, 2001) — Liu — ink replenishing device.
• 6,273,151 (Aug. 14, 2001) — Kong — refilling an ink cartridge.
• 6,106,180 (Aug. 22, 2000) — Anderka — handwriting/ink applying device.
• 2001/0040612 A1 (Nov. 15, 2001) — Shimizu — ink cartridge.
• 2001/0030675 A1 (Oct. 18, 2001) / 6,422,691 B2 (July 23, 2002) — Seiko Epson — ink cartridge.
• 2002/0039124 A1 (Apr. 4, 2002) — Nanjo — ink tank module/coupling.
• 2002/0186284 A1 (Dec. 12, 2002) — Anma — ink container package.
• 2003/0016279 A1 (Jan. 23, 2003) — Hayashi — ink tank.
• 6,254,068? not cited.

HP unitary/universal body and datum art: 6,260,961; 6,331,054; 6,290,348; 6,231,173 ("Contact pad and fluid interconnect configuration on a print cartridge"); 6,428,141.

Two-portion frame/cartridge background (relevant to two-material design): 5,464,578 (Nov. 7, 1995, HP — "Method of making a compact fluid coupler…"); 5,040,002; 6,088,461? not cited; 6,135,694 above.

Ink-jet diaphragm/actuator membrane head art (title-only, combination): 5,665,141 (Sharp); 5,757,401 (Sharp); 5,646,341 (Seiko Epson drive); 5,714,277? not cited; 5,821,966 (Xerox sealing); 6,186,177? not cited.

Still remaining in the examiner's 137-list (all combination art; brief):

• 5,434,603, 5,594,483, 5,426,459, 5,451,995, 5,573,490? (dedup with 5,575,490), 6,206,515, 6,341,853, 5,426,459, 6,084,617, 5,771,053, 6,010,211, 5,811,963, 6,422,691, 6,130,694, 6,250,747, 5,650,811, 6,138,694, 5,719,609, 5,923,353, 6,074,043, 5,992,986, 6,164,744, 6,227,654, 6,428,147, 6,391,603, 6,217,153, 6,312,615, 6,079,813, 2003/0052944 A1 (HP fluid manifold for printhead assembly), 6,383,436 (Seiko Epson process for producing ink-jet printer member), 6,247,791, 6,382,784, 2001/0006395, 6,203,146, 6,270,204, 6,130,690, 6,365,701, 6,394,137, 6,217,157, 2001/0040612, 6,106,180, 6,500,354, 6,172,695, 6,250,747, 2001/0019347 A1 (HP method for regulating pressure), 6,460,778, 2002/0024573, 6,325,354, 6,318,851, 6,228,050 (Medtronic overfill protection), 6,273,151, 6,250,769, 2002/0008744 A1 (HP dual serial pressure regulator), 6,290,348, 6,527,357, 2001/0017641 A1 (Epson ink-jet recording apparatus), 6,168,267, 6,260,961, 6,331,054, 6,243,115, 6,199,977, 6,478,406 (Silverbrook ejector), 6,416,165, 6,412,911, 2002/0039124, 2002/0191061 A1 (HP apparatus for providing ink), 2002/0080216 A1 (HP), 6,508,545 B2 (HP apparatus for providing ink), 2002/0105567 A1 (Brother), 6,371,605, 2002/0145650 A1 (Eastman Kodak ink level and negative pressure control), 6,428,141, 2002/0186284, 2003/0016279, 6,428,140, 6,536,875.
• Family-cited: 5,917,523 (June 29, 1999, HP — "Refill method for ink-jet print cartridge") — combination art.

Every one of the above was individually screened against the independent claims. None of the title-only entries discloses, on its face, the full combination of (separate higher-melting reservoir) + (separate lower-melting pressure control structure with aperture) + (sealing structure between reservoir sidewalls and the structure's side surface) + (film closing the aperture) + (protective cover).

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5. Bottom-line § 102 rankings

Honest caveat: A true § 102 anticipation case for independent claim 1 would require a single reference disclosing the separate, lower-melting-point pressure control structure mechanically sealed (o-ring or adhesive in a groove) into a higher-melting-point reservoir with a film over the aperture and a protective cover. Among the 137 cited references, none is a clean anticipatory reference for claim 1, 8, or 15 as I can verify from the available full texts and abstracts; the closest are 6,168,267 and 6,243,117 (structure) and, for the melting-point-differential/sealing concepts, the HP two-material-frame trio and 5,719,609. Full-text review of every one of the 137 references was not possible within this session's search budget; my assessments for the title-only entries are flagged accordingly and should be confirmed against the PDFs before reliance in a validity opinion.

I have good confirmation on the four key HP/Lexmark references. Let me verify a few more cited references that bear on the sealing structure, the cover, and the film-regulator elements.

Obviousness Analysis — U.S. Patent 6,817,707 B1 (35 U.S.C. § 103)

Disclaimer up front: This is a technical obviousness assessment built from the examiner-cited prior art appearing in the "Citations" record of the patent (verified against live Google Patents pages where noted below). It is not a legal opinion; final § 103 validity would depend on claim construction (which was actually contested in Slingshot Printing LLC v. HP Inc., No. 1:20-cv-00184-ADA), the prosecution history, and expert testimony.

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1. Legal framework applied

Under § 103, a claim is unpatentable if the differences between the claimed subject matter and the prior art are such that the subject matter as a whole would have been obvious at the time the invention was made to a person having ordinary skill in the art (PHOSITA). The Graham factors apply: (1) scope/content of prior art; (2) differences between prior art and claims; (3) level of ordinary skill; (4) objective indicia of non-obviousness. Under KSR Int'l Co. v. Teleflex Inc. (2007), a PHOSITA may combine prior-art teachings "in any way" that is obvious, including by "obvious to try" reasoning, when the field provides a finite number of identified, predictable solutions and the combination yields a predictable result. Reversal or reordering of routine manufacturing steps is obvious absent a showing of criticality.

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2. The claimed invention

The three independent claims cover one apparatus (claim 1) and two method variants (claims 8 and 15) that differ only in the order in which the pressure-regulating film is attached relative to insertion of the pressure control structure into the reservoir:

Dependent claims add: a peripheral groove (2); an elastomeric o-ring in the groove (3, 5); an adhesive bead in the groove (4); a semiconductor substrate + nozzle plate on the bottom wall (6); and melt-attachment of the film (7).

In substance, the patent claims a two-material, mechanically sealed cartridge body: a rigid, high-melting ink reservoir (cavity), into which a separate, low-melting polymer "lung" frame (PCS) carrying a pressure-regulating membrane is inserted and sealed by an o-ring/adhesive, then protected by a cover. The specification's own stated advantages reveal what the inventors viewed as the point of novelty: no two-step injection molding of inner/outer frames of different materials; parts "sub-assembled and combined using only mechanical means"; and a single-material (non-laminated) film.

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3. Person of ordinary skill in the art

A PHOSITA would be an engineer with a B.S. in mechanical or polymer engineering (or equivalent experience) and 2–4 years designing thermal ink-jet pens/cartridges: fluidics, back-pressure regulation, thermoplastic part design, and high-volume cartridge assembly (heat staking, welding, adhesive and gasket sealing).

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4. Prior-art pool (examiner-cited references on the record)

All references below appear in the patent's own citation list and have effective dates well before the June 18, 2003 filing date. Verified content is based on live Google Patents/free-patent-online retrievals performed today:

Also on the record: US 4,385,025 (coinjection molding of thermoplastic and thermoplastic elastomer) and US 2,609,570 (multi-part plastic articles), showing that multi-material, sequentially molded plastic assemblies were an old and general art; and a large HP/Lexmark free-ink, spring-bag, and diaphragm-regulator family (e.g., US 5,040,002; 5,451,995; 5,541,632; 5,646,666; 5,650,811; 5,719,609; 5,736,992; 5,757,406; 5,818, ...; 5,975,686; 6,130,694).

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5. Element-by-element mapping (Claim 1) against the art

The genuine differences between claim 1 and any single reference are therefore narrow: (i) the PCS is a separately formed part rather than integrally/over-molded with the reservoir; and (ii) it is sealed to the reservoir by a mechanical sealing structure (o-ring/adhesive) rather than by two-shot molding or welding.

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6. Proposed obviousness combinations

Combination A (strongest): R1 (US 5,440,333) + R2 (US 5,515,092) + R7 (US 5,821,966) [or equivalent seal art] → claims 1–7

Theory: R1 and R2, taken together, teach every material, structural, and assembly feature of claim 1 except the mechanical sealing structure — and R7 supplies that.

• R1 teaches a rigid, high-melting outer reservoir/housing and an inner frame of lower-melting plastic selected specifically so the flexible film can be heat-bonded to it (the identical functional rationale stated in '707: "making the pressure control structure from a material that enables melt attachment of a film thereto improves the manufacturing process"). R2 teaches the same two-material frame concept with heat/pressure sealing of the membrane film to the low-melt frame and expressly explains why two materials are used (structural rigidity of the outer frame; heat-sealability of the inner frame).
• R1/R2 join the inner frame to the housing by two-step injection molding/overmolding (R2's "locking features"). The '707 patent's own Background and Summary identify the manufacturing complication of multi-material printhead assemblies — and its own stated advantage is "no need for use of a two step injection molding process to provide inner and outer frames made of different materials" with parts "combined using only mechanical means." That admission frames the obvious design choice: a PHOSITA seeking to simplify HP's two-shot process would pre-form the low-melt frame as a discrete part and seal it into the reservoir with a conventional o-ring or adhesive bead — exactly the claimed structure.
• Sealing a molded thermoplastic frame into a mating cavity with an elastomeric o-ring seated in a peripheral groove, or a bead of adhesive, is a routine mechanical engineering expedient and appears in the cartridge-sealing art (R7 — "improved sealing between ink container and printhead"; R8 — redundant regulator sealing). Nothing in R1/R2 teaches away from a separable mechanical seal; to the contrary, R1 states the inner frame "may be separately constructed with some flexibility to assist in mounting it in the housing."
• The cover element is squarely taught by R1's cover plates and R3's side panel; adding a protective cover over the membrane is the obvious reason why such covers exist (protect the flexible wall and complete the enclosure).
• Reasonable expectation of success: every element is a known component performing its known function in the same cartridge environment; the combination is a simple substitution of a joining method (overmolding → mechanical seal), yielding the predictable result the '707 specification itself advertises (fewer materials-processing steps, no two-shot tooling, leak-tight seal from a commercial o-ring/adhesive).

Combination B (Lexmark-primary): R3 (US 6,168,267) + R2 (US 5,515,092 / US 5,440,333) + conventional seal → claims 1–7

Theory: R3 is the closest same-assignee reference — a pressure-controlled free-ink cartridge with a rigid injection-molded reservoir body, a lung-type pressure-regulator frame disposed in the ink cavity, and a side panel cover; '707's claim language and specification track R3's architecture and even repeat R3's background paragraphs nearly verbatim. The differences are again (i) the lung frame is integrally molded with the reservoir body rather than separate, and (ii) there is no o-ring/adhesive seal. Applying R2's teaching — form the frame separately from a lower-melting polymer so the membrane can be heat-welded to it while the body stays a higher-melting, dimensionally stable engineering plastic — is an obvious modification to solve the known tolerance/warpage problems of molding low-melt frames integrally with high-melt bodies (a problem R3 itself flags: "maintaining tolerances during the manufacture of the cartridge body becomes more difficult"). The seal is again conventional (R7). This combination maps cleanly onto every claim element.

KSR "obvious to try": the artisan seeking a heat-weldable frame + heat-resistant reservoir had a finite set of known options (polyethylene/polypropylene low-melt frame; NORYL-type high-melt body — the exact pair the '707 spec names as "most preferred"/"particularly preferred"), and the result was predictable.

Combination C: R4/R6 + R2 + R7 (back-pressure regulator art + two-material frame art)

US 5,541,632 and US 5,736,992 independently teach rigid cartridge/pen housings with flexible-wall negative-pressure reservoirs and regulators; R2 teaches the material pairing; R7 teaches the seal. Same analysis as Combination A with a different primary reference. These references also support dependent claim 6 (printhead/substrate attach to the cartridge) and the general back-pressure operating range described in the specification (−8 to −24 cm H₂O), which mirrors the negative-pressure operating discussion in R3/R4/R6.

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7. Method claims 8 and 15 (assembly-order variants)

Both claims add nothing patentably distinct over claim 1's structure plus conventional assembly steps:

• Claim 8 order (insert PCS into reservoir → attach film → attach cover): R5 (US 5,448,818) discloses essentially this sequence for a collapsible-reservoir cartridge: provide a peripheral frame → attach one flexible wall → insert the regulator assembly into the open frame → attach the remaining flexible wall; cover/panel attach appears in R1/R3. R9 (Lexmark 6,371,605 / 6,199,977) discloses cartridge body molding, ink fill, and panel attach sequences.
• Claim 15 order (attach film to PCS → insert subassembly → attach cover): this is the "build the regulator subassembly first" order used throughout the HP free-ink art — R5's method attaches a first sidewall to the frame to make an "open assembly" before insertion, and R1 describes assembling the reservoir structure (frame + membranes + regulator) before mounting it in the housing wall section. Both orders are thus found in, or are direct inversions of steps taught by, R1/R5.
• Reversing two manufacturing steps, where the patent itself states "Either method will provide an improved pressure controlled ink jet printhead assembly" (i.e., no criticality or unexpected result is asserted for the order), is obvious as a matter of routine process design.

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8. Dependent claims

• Claims 2–5 (peripheral groove; o-ring; adhesive bead): A groove in the side surface of an insert that seats an o-ring or adhesive bead is a conventional sealing geometry; o-rings and adhesive beads are expressly identified by the '707 specification itself as the preferred sealing means and are shown in the cartridge sealing art (R7, R8). No inventive step.
• Claim 6 (substrate + nozzle plate on bottom wall): Universal in the cited art (R4's snout-mounted printhead; the '707 spec's own chip/nozzle-plate arrangement is conventional thermal-inkjet structure).
• Claim 7 (melt-attached film): Expressly taught by R1 (heat bonding of bag walls to the lower-melting frame), R2 (heat/pressure joinder of film to the second plastic), and R5 (heat staking). The "single material film" preference in the '707 spec is simply the elimination of an adhesive layer — an obvious materials simplification once a heat-weldable frame/film pair (R1/R2) is used.

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9. Secondary considerations / counterarguments

• No strong objective indicia on this record. The file wrapper was not reviewed here. Given that the family was litigated (Slingshot v. HP, W.D. Tex. 6:19-cv-00362 → 1:20-cv-00184), any commercial-success or long-felt-need evidence would need to be weighed — but nothing in the searchable record suggests such evidence was outcome-determinative, and both district cases closed without a reported merits decision on this patent.
• Plausible patentee counterarguments (and why they are weak on this record):
  1. "No single reference shows a separate low-melt frame mechanically sealed into a high-melt reservoir." True — but that is a combination, not a new principle; each element is in the art with an articulated reason for combining (avoid two-shot molding; heat-weldability of film; seal integrity).
  2. "The prior art two-material frames were bags/collapsible reservoirs, not rigid-cavity lung regulators." R3 shows a rigid-cavity lung regulator in the same assignee's product line; swapping the lung frame's material and joining method per R1/R2 is an obvious modification of a known cartridge.
  3. "O-rings in ink contact raise chemical-compatibility concerns." The '707 spec answers this itself — an ink-resistant elastomer (EPDM) is a routine selection; the specification identifies no unexpected compatibility problem.
  4. "The two assembly orders are independent inventions." The specification disclaims any criticality of order, which under KSR defeats a non-obviousness argument based on step ordering.

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10. Bottom line

Claims 1–7 of US 6,817,707 are highly susceptible to a § 103 challenge on the examiner-cited record, most forcefully via:

1. US 5,440,333 + US 5,515,092 + US 5,821,966 (HP two-material low-melt-frame art + cartridge seal art), or
2. US 6,168,267 + US 5,515,092/5,440,333 + conventional o-ring seal (Lexmark's own rigid-cavity lung-regulator cartridge modified with HP's low-melting, heat-weldable separate frame).

Method claims 8 and 15 are obvious over US 5,448,818 (and US 5,440,333 / US 6,168,267 / Lexmark's manufacturing-method patents) because both claimed assembly orders are taught or are trivial inversions of taught steps with no asserted criticality. Dependent claims 2–7 add only conventional sealing geometries, printhead attachment, and heat-welding of the film — all well documented in the cited art.

The core claimed advance — avoiding two-shot molding by mechanically sealing a separately molded, lower-melting regulator frame into a higher-melting reservoir — is, on this record, the kind of combination of known elements with predictable results that KSR treats as classic obviousness, and the '707 specification's own statement of advantages supplies the motivation language a challenger would need.

Key references (verified live):

• US 5,440,333 — patentimages.storage.googleapis.com/85/f4/49/b59071101e78f3/US5440333.pdf; FreePatentsOnline.com/5440333.html (lower-melting inner frame; two-step molding; heat-welded membranes; cover plates).
• US 5,515,092 — patents.google.com/patent/US5515092 (two-material frame; heat/pressure film joinder; overmolding with locking features).
• US 5,448,818 — patentimages.storage.googleapis.com/78/88/77/791b333d8bfd64/US5448818.pdf (heat-seal assembly method sequence).
• US 5,541,632 — patents.google.com/patent/US5541632 (rigid housing, cover plates, flexible reservoir membranes, regulator).
• US 5,736,992 — patents.google.com/patent/US5736992A (periphery-mounted regulating diaphragm; negative back-pressure set point).
• US 6,168,267 — patents.google.com/patent/US6168267; uspto.report/patent/grant/6168267 (Lexmark rigid-body lung-regulator cartridge; Komplin; filed 2000-02-23).
• US 5,821,966, US 6,250,747, US 6,199,977, US 6,371,605 — titles/dates as listed in the '707 citation record; content relied on only to the extent of their titles and conventional role in the cartridge art, which I could not fully re-verify within tool limits.