US 6243115

I'll search for the specific patent 6243115 in USPTO records and CAFC dockets.

Let me search specifically for any CAFC (Federal Circuit) appeal activity, including 2026 dockets, tied to patent 6,243,115.

Summary of U.S. Patent 6,243,115 B1

I searched USPTO-related databases, patent portals, and Federal Circuit/PTAB records for the specific number 6243115 (U.S. Patent No. 6,243,115, publication US6243115B1). Below is what the authoritative sources show.

Bibliographic data

• Title: Pressurized ink supply and delivery system for an ink jet printer
• Patent / publication number: US 6,243,115 B1 (application serial no. 09/522,105)
• Inventors: Ronald Willard Baker, Philip Jerome Heink, Jeffrey Lynn Richie, Donald Wayne Stafford
• Original assignee (at grant): Lexmark International, Inc.
• Later assignees (chain of title): Funai Electric Co., Ltd. (assignment recorded 2013-05-14, effective 2013-04-01) → Slingshot Printing LLC (assignment recorded 2019-03-29) — per Google Patents assignment records
• Filing date: March 9, 2000
• Issue/publication date: June 5, 2001 (Espacenet and Google Patents agree on 2001-06-05; the Unified Patents portal lists a grant date of 2001-06-04 and priority date of 2000-03-08 — a minor discrepancy, so treat the exact "grant date" as 2001-06-05 per USPTO/Google/Espacenet records)
• Status: Expired – Lifetime (term expired/anticipated expiration 2020-03-09/2020-03-08; all maintenance fees paid through year 12)
• Classification: IPC/CPC B41J2/175 (ink supply systems), B41J2/17513, B41J2/17556
• Representative sources: Google Patents (patents.google.com/patent/US6243115B1/en), Espacenet, USPTO via uspto.report/patent/grant/6243115, freepatentsonline.com/6243115.html

Abstract (verbatim from the patent)

"An ink supply and delivery system for a printer cartridge including a printer cartridge having an interior, at least one air inlet to the interior, and at least one ink outlet from the interior. An air pump is connected to the air inlet of the printer cartridge and creates a positive pressure in the interior of the printer cartridge. The system further includes an ink source, including ink, in the interior of the printer cartridge, the ink source in fluid communication with the ink outlet of the printer cartridge whereby the positive pressure created by the air pump in the interior of printer cartridge forces ink to flow from the ink source in the interior of the printer cartridge through the ink outlet. The ink source is preferably in a resilient container, and the system alternately includes a resilient air container either within, next to, or encapsulating the resilient container of the ink source. The printer cartridge alternately includes a vent to partially vent any accumulated pressure that has escaped from the resilient air container into the interior. There is further disclosed a method of supplying ink from a printer cartridge in a printer that prints upon a media…"

Overview of the invention

The patent addresses the problem that ink-jet printers historically used small disposable cartridges combining the ink supply with the nozzle array, yielding high cost-per-page and short user-intervention intervals. The solution is a pressurized, pump-driven ink delivery system: a printer cartridge contains an ink source (e.g., a collapsible bag) and a resilient air container; an air pump (with a pressure regulator, ~1–2 psig) pressurizes the air container, which expands to squeeze ink out through the ink outlet to the print head. Four structural arrangements are depicted: (Fig. 1) direct pressurization of a hermetically sealed cartridge interior; (Fig. 2) a resilient air bladder inside an ink-filled cartridge; (Fig. 3) a resilient air container encapsulating the ink bag; and (Fig. 4) a resilient air bladder inside the ink bag.

Independent claims (claims 1, 9, and 15 are the only independent claims; total 19 claims)

• Claim 1 (apparatus): An ink supply and delivery system for a printer cartridge comprising: a printer cartridge having an interior, at least one air inlet, and at least one ink outlet; an air pump connected to the air inlet for creating a positive pressure in the interior; an ink source (with ink) in the interior, in fluid communication with the ink outlet; and a resilient air container in the interior, in fluid communication with the air inlet, the air container expanding under the positive pressure from the air pump to force ink from the ink source through the ink outlet.
• Claim 9 (apparatus, means-plus-function form): The same basic system but expressed functionally: a "pressure supply means" (connected to the air inlet) for creating positive pressure; an "ink supply means" (with ink in the interior, in fluid communication with the ink outlet) for supplying ink; and a "resilient air containing means" in the interior, in fluid communication with the air inlet, expanding under pressure to force ink through the ink outlet.
• Claim 15 (method): A method of supplying ink from a printer cartridge in a printer, comprising: placing the cartridge into the printer; creating positive pressure in a resilient air container in the interior by activating the air pump (the container being in fluid communication with the air inlet and expanding); supplying ink from a resilient container acting as the ink source by forcing ink through the ink outlet with the expansion of the air container; and printing on media with the supplied ink.

(Dependent claims 2–8 add, e.g., hermetic sealing, the ink source being a resilient container/bag, an air vent, and air-container positioning within or encapsulating the ink container; claims 10–14 mirror those limitations in means-plus-function form; claims 16–19 add venting, positioning/encapsulation method variants, and specifying an ink jet printer.)

Litigation / post-grant history (relevant to "6243115")

• District court: Slingshot Printing LLC v. HP Inc., W.D. Tex. (e.g., No. 1:20-cv-00184-ADA and related cases, including 6:19-cv-00362), asserting the '115 patent among others. Claim-construction and invalidity-contentions activity occurred through 2020.
• PTAB: HP Inc. v. Slingshot Printing LLC, IPR2020-01085, filed June 15, 2020, challenging claims 1–19; institution granted Jan. 14, 2021; proceeding terminated–settled on March 29, 2021 (joint motion to terminate filed March 16, 2021). No final written decision issued.
• CAFC 2026 dockets: I found no Federal Circuit docket entry for 2026 (or any year) specifically naming U.S. Patent 6,243,115. The 2026 Federal Circuit decisions involving Slingshot Printing that appeared in my searches (Slingshot Printing LLC v. Canon U.S.A., Inc., Fed. Cir. Nos. 2025-1033/2025-1034, decided July 16, 2026, and related July 2026 dispositions) concern different patents (e.g., U.S. Patent Nos. 7,594,708 and 7,484,823) — not 6,243,115. Do not confuse those case numbers with this patent.

Uncertainty notes

• I could not confirm any active 2026 CAFC appeal for 6,243,115; given the patent's 2020 expiration and the 2021 settlement/termination of the HP IPR and the settlement-driven PTAB termination, no live appellate matter tied to this patent number surfaced.
• Minor date discrepancies exist between secondary aggregators (Unified Patents lists priority 2000-03-08 and grant 2001-06-04; Google Patents/Espacenet list filing 2000-03-09 and publication 2001-06-05). I would treat the USPTO/Google/Espacenet dates as authoritative.
• I did not directly query the USPTO's PatFT/PatentCenter or the CAFC's CM/ECF system itself (no such live database access is available to me); my conclusions rest on the public web sources cited above.

Let me verify the filing details and current status of the two district court cases, and check whether any related cases (e.g., 6:19-cv-00549 or the 1:20-cv-00185 series) also involved this patent.

Based on searches of the Unified Patents litigation database (portal.unifiedpatents.com), PTAB records (IPR2020-01085 docket), Justia/PACER-derived dockets, and related sources, here is the known litigation specifically involving U.S. Patent 6,243,115 ("Pressurized ink supply and delivery system for an ink jet printer"). I found no Federal Circuit appeal naming this patent.

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1. District Court — Slingshot Printing LLC v. HP Inc.

Case No. 6:19-cv-00362-ADA (W.D. Tex., Waco Division — Judge Alan D. Albright)

• Plaintiff: Slingshot Printing LLC
• Defendant: HP Inc.
• Filed: June 11, 2019 (complaint; amended complaint filed Aug. 13, 2019)
• Patents: Included U.S. Patent 6,243,115 (among other Slingshot patents)
• Status: Closed (per Unified Patents). HP moved to dismiss under Rules 12(b)(6)/(7) and to stay; the parties stipulated to transfer venue to the Austin Division, where the matter continued under the docket below. The case terminated in connection with the parties' March 2021 settlement.

Case No. 1:20-cv-00184-ADA (W.D. Tex., Austin Division — Judge Albright)

• Plaintiff: Slingshot Printing LLC
• Defendant: HP Inc.
• Filed: The Unified Patents docket shows "Initial Civil Docket 06-11-2019" and "Final Civil Docket 04-01-2021." This is the Austin Division re-docketing/continuation of the June 11, 2019 Waco filing (the "1:20" number reflects its 2020 Austin-division docketing). The complaint in this case was submitted as Exhibit 2001 in the IPR below.
• '115 patent assertions: HP's Preliminary Invalidity Contentions in this case (served 2020) identify the '115 patent as a patent-in-suit, with Slingshot asserting claims 1, 3, 5, 6, 9, and 11–13 (priority date asserted as March 9, 2000).
• Status: Closed (docket closed April 1, 2021, following the Slingshot–HP settlement that also ended the IPR).

Note: The 1:20-cv-00185 through 1:20-cv-00189 series (also Slingshot v. HP, W.D. Tex., Austin Division) were part of the same multi-case dispute, but the patent-filtered case list on Unified Patents ties the '115 patent only to 6:19-cv-00362 and 1:20-cv-00184; those companion cases concern Slingshot's other patents.

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2. PTAB — Inter Partes Review

HP Inc. v. Slingshot Printing LLC, IPR2020-01085

• Petitioner: HP Inc.
• Patent Owner: Slingshot Printing LLC
• Filed: June 15, 2020
• Patent challenged: U.S. Patent 6,243,115, claims 1–19
• Institution: Granted January 14, 2021
• Outcome: Terminated — Settled (termination decision March 29, 2021; joint motion to terminate filed March 16, 2021, with a confidential settlement/license agreement). No final written decision was issued.

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Summary observations

• All litigation over the '115 patent was between Slingshot Printing LLC (plaintiff/patent owner) and HP Inc. (defendant/petitioner), in the Western District of Texas and at the PTAB.
• The entire dispute was resolved by settlement in March 2021 — the district court cases are closed and the IPR was terminated without a merits decision.
• The patent expired by operation of law in March 2020 (anticipated expiration date 2020-03-08/09 per record), and I found no CAFC appeal naming this patent number. (Recent 2026 Federal Circuit Slingshot decisions concern other patent numbers, e.g., in the Slingshot v. Canon matters, and should not be confused with this patent.)

Caveat: I could not independently verify the precise mechanics of the Waco-to-Austin transfer/renumbering (i.e., whether 1:20-cv-00184 is a formal transfer of 6:19-cv-00362 or a related re-filing) beyond the docket metadata showing initial docket date 06-11-2019 and the Austin Division caption. Exact dismissal/termination orders would require PACER confirmation.

Proceedings overview

Web research confirms one AIA trial proceeding has ever been filed on US 6,243,115 — IPR2020-01085 (HP Inc. v. Slingshot Printing LLC) — which was instituted on 2021-01-14 and then terminated by settlement on 2021-03-29 before any Final Written Decision. Net result: zero claims canceled, zero claims sustained on the merits, and no active PTAB proceeding. (Note: the structured "PTAB proceedings on file" block from the USPTO ODP API shows no proceedings — that is an ingest gap, because IPR2020-01085 is confirmed by multiple independent sources including the PTAB papers themselves, DocketAlarm, and ipverse/Greyb. Flagging that discrepancy per instructions.)

Bottom-line defensive posture: this patent is expired (term ran out 2020-03-09) and was never weakened by the PTAB — but also never validated by one; the only IPR was settled (HP took a license) before a merits decision, so all 19 claims remain exactly as issued, and no estoppel binds any defendant other than HP and its privies. For a defendant hit with a demand letter today, the controlling facts are the expiration date and 35 U.S.C. § 286, not the PTAB record.

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IPR2020-01085 — HP Inc. v. Slingshot Printing LLC

• Type: Inter Partes Review
• Filed: 2020-06-15
• Status: Terminated-Settled (terminated 2021-03-29, two days after the parties' joint motion; institution had been granted 2021-01-14, so the case was terminated after institution but before any Final Written Decision)
• Judge panel: Not directly confirmed from the retrieved IPR2020-01085 documents. HP's parallel same-day IPRs against the same Slingshot portfolio (e.g., IPR2020-01090 on US 7,244,015; IPR2020-01659 on US 7,410,246) were before APJs Garth D. Baer (lead), John D. Hamann, and Stacy B. Margolies (per Patexia/DocketAlarm), and it is highly likely — though not independently verified in my sources — that IPR2020-01085 was heard by the same panel.
• Petition grounds (claims 1–19, all challenged; independent claims 1, 9, 15):
  • Ground 1: § 102(a)/§ 102(e) — anticipated by Childers (US 6,116,723, Ex. 1004) — claims 1–4, 6–11, 13–15, 17–19
  • Ground 2: § 103(a) — obvious over Childers — claims 1–19
  • Ground 3: § 103(a) — obvious over Childers + Buck (US 4,500,895, Ex. 1005) — claims 5, 12, 16 (the "air vent" dependents)
  • Supported by the Declaration of Stephen F. Pond, Ph.D. (Ex. 1002). See Petition at 7, 15, 31–104, as summarized in the Institution Decision.
• Institution decision: Instituted — Paper 12 (Trial Instituted Document), 2021-01-14. The panel found "that there is a reasonable likelihood that Petitioner would prevail in establishing the unpatentability of at least one challenged claim of the '115 patent" (35 U.S.C. § 314(a)). Patent Owner's Preliminary Response had pressed discretionary denial under Fintiv (parallel W.D. Tex. litigation, Slingshot Printing LLC v. HP Inc., No. 1:20-cv-00184-ADA, with trial said to be scheduled about five months before the projected FWD deadline), plus Appointments Clause and word-count objections; the Board nonetheless instituted. My retrieved excerpts do not show the claim-by-claim/ground-by-claim institution breakdown, so I cannot confirm whether institution covered every claim on every ground — only that trial was instituted.
• Final Written Decision: None issued. The case settled approximately two months after institution, so there is no merits determination at any claim-level granularity. No claim of the '115 patent has been canceled (or affirmed) by the Board.
• Settlement / termination: On 2021-03-16 the parties filed a Joint Motion to Terminate (Paper 14) representing that they "have settled their dispute and executed a settlement agreement," together with a Joint Request to Treat the Settlement Agreement as Business Confidential Information (Paper 15) and the confidential "Slingshot-HP Settlement License and Release Agreement" (Confidential Ex. 1008), filed under 37 C.F.R. § 42.74(b)–(c). The Board entered a Termination Decision on 2021-03-29 (Paper 16); status is Terminated-Settled. The settlement terms (including any license scope and consideration) are confidential and not publicly available. One procedural curiosity: the Joint Motion recites that "the Board has yet to issue an institution decision" and cites PGR's § 327(a) — boilerplate that is factually wrong for this case (institution occurred 2021-01-14) and appears to be recycled template language; it did not affect the outcome.
• Appeal: None. With no Final Written Decision there was nothing to appeal under 35 U.S.C. § 319, and no Federal Circuit appeal exists for this proceeding. (The 2026 CAFC decisions involving Slingshot concern different patents — not 6,243,115.)
• Defensive value: For HP, the IPR plus the global settlement produced a license and dismissal of the W.D. Tex. suits — HP is out. For anyone else facing assertion of the '115 today, this proceeding is a double-edged signal: no claim was invalidated, so there is no FWD to lean on; but the Childers/Buck roadmap is fully public, the Board found a "reasonable likelihood" of unpatentability on at least one claim, and no estoppel attaches to a new petitioner, who may raise Childers, Buck, and any other § 102/§ 103 art. Far stronger than any IPR argument, however, is the patent's expiration and the § 286 damages bar (below).

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Strategic summary

Claim status — CANCELED vs. SUSTAINED vs. UNTESTED. No claim of US 6,243,115 has ever been canceled by the PTAB, and no claim has ever been sustained in a Final Written Decision. Claims 1–19 were all challenged in IPR2020-01085, trial was instituted, and the case then settled — leaving every claim (independent claims 1, 9, 15 and dependents 2–8, 10–14, 16–19) challenged but unresolved on the merits. The claims are not "hardened" by an IPR win, but they are also not dead. What is dispositive for practical enforcement: the patent's term expired 2020-03-09 (20 years from the 2000-03-09 filing; Unified Patents lists 2020-03-08 — a minor aggregator discrepancy), the status is "Expired – Lifetime," and all maintenance fees were paid through year 12. An expired patent cannot support an injunction, and under 35 U.S.C. § 286 damages are limited to infringing acts within six years before suit — so any complaint filed after 2020-09-08 reaches back only into the post-expiration period, where there are no damages. Practically speaking, a 2026 demand letter premised on the '115 is close to worthless.

Estoppel landscape. 35 U.S.C. § 315(e)(2) estops only HP Inc. and its privies from asserting in district court (or ITC) any ground that HP raised or reasonably could have raised in IPR2020-01085. That matters little for HP, which settled and is licensed. For a new defendant, the slate is clean: Childers (US 6,116,723), Buck (US 4,500,895), and every other § 102/§ 103 combination remain fully available, and the IPR institution decision gives a ready-made template showing how the art maps onto the claims. There is no PGR or CBM exposure (the patent issued in 2001, well before the AIA's nine-month PGR window and outside CBM subject matter).

Pattern signals. HP's petition was one salvo in a coordinated, same-day (2020-06-15) wave of IPRs against Slingshot's multi-patent assertion campaign — Slingshot (the Funai/Lexmark-derived NPE that now owns the '115) had sued HP in W.D. Tex. over 31 inkjet patents (including the '115 in 6:19-cv-00362 and 1:20-cv-00184-ADA, both since closed). All of those IPRs terminated-settled together in late March 2021, and Slingshot dismissed the Texas suits. The Google Patents entry credits "Unified Patents PTAB Data" for the IPR listing, but that is data attribution only — Unified Patents was not the petitioner; HP Inc. was, through Morgan Lewis (lead counsel Dion Bregman). The takeaway: this patent has been through exactly one contested PTAB challenge, and that challenge was resolved by a confidential global license, not by merits adjudication.

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Recommended next steps

• If you are a defendant and the patent is asserted against you: do not anchor your defense on PTAB invalidity — there is no FWD to cite. Your lead arguments should be (1) expiration — the patent lapsed 2020-03-09, so no injunction is available and no post-expiration damages exist; and (2) 35 U.S.C. § 286 — with the six-year lookback running from filing, any 2026 complaint cannot capture the pre-expiration window, leaving a zero-damages case. Pull the two key PTAB papers from USPTO PTAB E2E (search "IPR2020-01085"): the Institution Decision, Paper 12 (2021-01-14) and the Termination Decision, Paper 16 (2021-03-29) — copies are also accessible via DocketAlarm (https://www.docketalarm.com/cases/PTAB/IPR2020-01085/) and ipverse/Greyb (https://ipverse.greyb.com/ptab-web/cases/case-details/IPR2020-01085).
• If you want your own IPR anyway (e.g., to clear the record or for use in a parallel dispute): no estoppel blocks you, and the Childers/Buck grounds are proven-institutional-quality art. But weigh the costs — the Board can and often does exercise discretion over petitions on expired patents, the patent has no forward-looking value, and the § 286 bar already achieves the defense outcome. Verify real-party-in-interest and § 315(b) timing before filing.
• No active proceedings, no pending deadlines. The PTAB docket is closed (terminated 2021-03-29); there is no institution-decision deadline, oral hearing, or FWD date to calendar. If the ODP "no proceedings" block caused confusion, that is simply an indexing gap — IPR2020-01085 is real and is the complete PTAB history of this patent.

Confidence notes: I did not retrieve the full text of the Institution Decision, so the ground-by-ground institution scope and the IPR2020-01085 panel composition are not confirmed at the same confidence as the case-level dates, which are corroborated by multiple sources. The settlement terms are confidential (Ex. 1008 sealed under § 42.74(c)). No CAFC appeal exists for this patent or this IPR.

Ownership & NPE analysis — US 6,243,115 B1

Sources used: USPTO assignment data as surfaced via Google Patents legal events (reels 010650/0293, 030416/0001, 048745/0551), Espacenet INPADOC, RPX Insight (June 12, 2019), The Recycler (June 2019), Actionable Intelligence, Unified Patents portal (parent-company and NPE flags; IPR dockets), and earlier CAFC/PTAB research in the prior sections of this file. I was not able to open USPTO Assignment Center directly in this session, so per-assignment correspondent names could not be verified (flagged below); everything else is sourced.

Inventors

• Ronald Willard Baker — Lexmark International, Inc. employee at filing (assignor to Lexmark, reel 010650/0293; all four inventors executed a single assignment to Lexmark dated 2000-03-06).
• Philip Jerome Heink — same.
• Jeffrey Lynn Richie — same.
• Donald Wayne Stafford — same.

All four are named assignors to Lexmark International, Inc. on the original assignment recorded 2000-03-09, which is consistent with employment at Lexmark's Lexington, Kentucky inkjet-printhead/cartridge development operation. Unusual departure pattern: none detectable — I have no data on whether any inventor left Lexmark within 12 months of filing, so that tell is unverifiable, not present.

Original assignee

Lexmark International, Inc. — the entity named on the issued patent (granted 2001-06-05) and the assignee of the original inventors' assignment (reel 010650/0293). Lexmark was an operating printer OEM (IBM printer spinoff) that manufactured and sold inkjet printers and cartridges; the '115 pressurized ink-delivery claims sit squarely in its inkjet hardware line, so the original assignee was an operating company with a product business, not a shell. Lexmark exited the inkjet hardware business in 2012–2013, selling the inkjet technology platform and >1,500 US/foreign patent assets to Funai Electric Co., Ltd. for roughly $100M (trade press; RPX). Lexmark itself continued operating (enterprise imaging/software) and was taken private by a Chinese consortium (Apex/Ninestar-related) in 2016 — not a bankruptcy. Current status: operating (privately held).

Assignment timeline

Per USPTO recorded data (as indexed by Google Patents legal events), exactly three recorded conveyance events exist for this patent — the original inventors' assignment plus two portfolio transfers. No security agreements, licenses, mergers, or changes of name are recorded against '115.

• 2000-03-06 (executed) / recorded 2000-03-09 — Reel 010650/0293

  • Conveyance: Assignment of Assignors' Interest
  • Assignor: Ronald Willard Baker; Philip Jerome Heink; Jeffrey Lynn Richie; Donald Wayne Stafford
  • Assignee: Lexmark International, Inc. (Kentucky)
  • Correspondent: not retrievable in this session (USPTO Assignment Center not directly accessible); expected to be Lexmark's prosecution counsel of record. Recurrence check: unable to perform.
  • Context: Standard employment-era assignment from inventors to employer on the filing date.

• 2013-04-01 (effective) / recorded 2013-05-14 — Reel 030416/0001

  • Conveyance: Assignment of Assignors' Interest
  • Assignor: Lexmark International, Inc. and Lexmark International Technology, S.A. (Lexmark's Luxembourg IP-holding affiliate — the inkjet patents were held partly through that affiliate)
  • Assignee: Funai Electric Co., Ltd. (Japan)
  • Correspondent: not retrievable in this session. Recurrence check: unable to perform.
  • Context: Strategic divestiture — Lexmark's exit from the inkjet business, ~$100M portfolio sale to Japanese consumer-electronics maker Funai (announced April 2013 per RPX).

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

  • Conveyance: Assignment of Assignors' Interest
  • Assignor: Funai Electric Co., Ltd.
  • Assignee: Slingshot Printing LLC (Maryland)
  • Correspondent: not retrievable in this session. Recurrence check: unable to perform.
  • Context: Transfer-to-asserter — newly formed LLC (per RPX, "recently formed NPE... received more than 100 US assets from Funai") received the patent roughly 10 weeks before filing its first infringement suits on it. Note: RPX reported that the recorded assignments "suggest that Funai might hold an economic interest in Slingshot's litigation," so Funai may have transferred legal title while retaining a revenue stake — the classic privateering structure. (One secondary source, The Recycler, dated the Funai→Slingshot transfer "April 2019"; the USPTO record and Google Patents show effective/recorded date 2019-03-29 — I treat the USPTO date as authoritative.)

Current assignee per Google Patents and the Unified Patents portal: Slingshot Printing LLC.

Timeline diagram

timeline
    title Ownership of US 6243115
    2000 : Filed by Lexmark
         : Inventors assign to Lexmark
    2001 : Patent issued
    2013 : Lexmark inkjet sale to Funai
    2019 : Funai assigns to Slingshot LLC
         : Slingshot sues HP in Texas
    2020 : HP files IPR challenge
    2021 : IPR settled and terminated

NPE / troll-pattern signals

1. Shell-entity transfer — present. Reel 048745/0551 (2019-03-29) moved the patent from Funai (a manufacturer, albeit one exiting inkjet) to Slingshot Printing LLC, a Maryland LLC formed to hold and assert former Lexmark inkjet patents. RPX (June 12, 2019) calls Slingshot a "recently formed NPE"; Unified Patents flags Slingshot as "NPE (Patent Assertion Entity)" in its PTAB filings (e.g., IPR2022-01416) and lists Slingshot as the '115 parent company. Slingshot ships no products; its only activity is assertion.

2. Known asserter in the chain — present. Slingshot Printing LLC is a high-frequency plaintiff tracked by RPX and Unified Patents (suits against HP in W.D. Tex. 2019–2020 — 6:19-cv-00362, 1:20-cv-00184 and related — then Canon in 2022, with multiple PTAB/CAFC follow-ons). RPX Insight's June 12, 2019 piece explicitly opens "New NPE Begins Litigating Former Lexmark Patents." It is not on the named legacy list (Acacia, Marathon, IV, etc.), but it squarely matches the "entity surfaced by Unified Patents or RPX as a high-frequency plaintiff" criterion.

3. Repeat correspondent across the chain — unclear / not assessable. I could not open the USPTO Assignment Center records in this session to capture correspondent names for reels 010650/0293, 030416/0001, or 048745/0551. No recurrence can be confirmed or excluded on this record. (Slingshot's PTAB counsel of record is Fitch, Even, Tabin & Flannery LLP per Unified Patents IPR dockets, but that is litigation counsel, not the assignment correspondent.)

4. Cascading transfers — not present. Only three recorded events over 19 years (2000, 2013, 2019); no rapid chained-LLC sequence in <24 months.

5. Pre-litigation transfer — present. Reel 048745/0551 recorded 2019-03-29; the first Slingshot complaints naming '115 were filed against HP on 2019-06-11 (W.D. Tex. 6:19-cv-00362 et al., per The Recycler and the Unified Patents litigation docket). That is ~10 weeks — well inside the 6-month window — and the transfer was to the entity that immediately filed suit, i.e., the chain was arranged to enable assertion with a clean standing record.

6. Bankruptcy fire-sale — not present. Lexmark never filed bankruptcy; the 2013 Lexmark→Funai transfer was a negotiated exit from the inkjet business (~$100M), not a §363 asset sale. (Funai's own later financial distress is not part of the recorded '115 chain and is not needed for this analysis.)

7. Privateering — present. Funai (the operating company that owned the patents 2013–2019) transferred >100 assets to NPE Slingshot in March 2019, and RPX reported the assignment records suggest Funai retained an economic interest in Slingshot's litigation. Slingshot then asserted against printer OEM competitors of Funai's former inkjet business (HP, later Canon/Brother). That is the textbook privateering profile: operating company + litigation vehicle asserting against competitors, with a retained revenue share.

8. Defensive aggregator (anti-NPE) — not present. The chain terminates at Slingshot Printing LLC, an asserting NPE. No RPX, AST, LOT, Unified Patents, or OIN interest at the end of the chain. (HP's IPR2020-01085 was a defensive challenge, not an acquisition, and it ended in settlement/termination on 2021-03-29, not in the patent being neutralized.)

Verdict

NPE — high confidence.

Three independent, strong signals converge: (1) the 2019-03-29 Funai→Slingshot transfer (reel 048745/0551) to a no-products Maryland LLC that RPX and Unified Patents both classify as an NPE; (2) the pre-litigation timing — assignment recorded 2019-03-29 with the first '115 complaints filed 2019-06-11 (W.D. Tex. 6:19-cv-00362 et al.); and (3) privateering indicia — Funai transferred title while reportedly retaining an economic interest, and Slingshot asserted the former Lexmark/Funai portfolio against printer OEMs HP and Canon. Slingshot Printing LLC is the current assignee and is the asserting party. Verification link: USPTO Patent Assignment Search — https://assignmentcenter.uspto.gov/ (search patent number 6,243,115; reels 010650/0293, 030416/0001, 048745/0551).

I'll verify the cited references against live sources before analyzing them. Let me run several searches in parallel.

Good — key references confirmed. Let me verify the remaining cited references.

Scope note

This section builds on the previously generated patent summary, litigation summary, PTAB analysis, assignment history, and obviousness analysis. It does not repeat their content except where cross-reference is needed. The task here is narrower: (a) confirm identity of US 6,243,115, and (b) walk each of the 12 patents cited on the face of US 6,243,115 and state, per reference, the full citation, dates, disclosure, and whether it could anticipate under 35 U.S.C. § 102.

I flag two limits up front: (1) The searches below returned full text for US4558326A, US6030074A, US5870124A, US4734711A, and US5877793A; the remaining seven were verified only at title/bibliographic level in this session (searches for US4575738A, US4982200A, US5446486A, US5453770A, US5719609A, US5757390A, and US5877795A hit the session step limit and returned no content), so their descriptions rest on their titles and the patent's own citation table. (2) A strict reading of the task's "do not auto-correct" rule is followed: all numbers are read exactly as printed in the record. Minor date discrepancies among aggregators are flagged, not corrected.

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1. Identity confirmation

The number 6243115 resolves to a single, distinct patent — US 6,243,115 B1, "Pressurized ink supply and delivery system for an ink jet printer," application 09/522,105, filed 2000-03-09, granted 2001-06-05, original assignee Lexmark International, Inc. This is not to be confused with any similar number (e.g., 6,243,110, 6,243,115-series neighbors, or the "6:19-cv-00362" case number). The Google Patents "Prior art keywords" for this document are: ink, printer cartridge, interior, air, container — which frames exactly the element set analyzed below.

The document carries 12 cited patent references and no cited non-patent literature. One of them — US6030074A — carries the examiner-cite marker ("*") in the record, i.e., it was the examiner's own citation.

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2. The § 102 standard and the gating limitation

Anticipation under § 102 requires a single prior-art reference to disclose every claimed element, arranged as claimed. The dispositive element in this patent is not the cartridge, inlet, outlet, pump, or ink bag — all of which are old. It is the final element of each independent claim (1, 9, 15):

"a resilient air container in the interior of the printer cartridge and in fluid communication with the air inlet, the air container expanding from the positive pressure created by the air pump for forcing the ink from the ink source through the ink outlet."

Every dependent claim (2–8, 10–14, 16–19) incorporates that element through its independent parent. Consequently, no reference can anticipate any issued claim unless it discloses a resilient, inflatable air chamber that expands under pump pressure to squeeze ink out of the cartridge. As shown below, that is precisely where each of the 12 cited references falls short — which is why the patent issued over them. The cited art is best characterized as § 103 material, not § 102 anticipation art (consistent with the earlier obviousness section, which used these same references in combinations).

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3. The 12 cited references

3.1 US 4,558,326 A — the "flexible bag in a rigid, gas-pressurized cartridge" reference

• Full citation: U.S. Patent No. 4,558,326, "Purging system for ink jet recording apparatus," Konishiroku Photo Industry Co., Ltd.
• Dates: JP priority 1982-09-07; filed 1983-09-06; granted 1985-12-10
• Disclosure (verified): An ink-on-demand recorder in which a flexible ink container bag is housed inside a rigid, nearly airtight cartridge body pierced with a vent/gas opening. A pressurized gas supply connected to that opening raises pressure inside the rigid body, which flexes the bag to pressurize ink, delivered through an elastic cap/connector to the head (used for purging bubbles). The patent touts "always constant pressure regardless of the residual quantity of the ink." Some embodiments (Figs. 10–11) use two openings.
• Potential § 102 relevance: This is the closest thing in the cited art to the unclaimed FIG. 1 embodiment of '115 (a cartridge whose interior is directly pressurized so a flexible ink bag collapses). It discloses claim-3 and claim-4 subject matter (ink source is a resilient container / a bag) and the claim-2-type closed-body concept. It does not disclose the resilient, expanding air container of claims 1/9/15, and its cartridge body has a vent opening (undercutting the "hermetically sealed" claim 2). Anticipation: none of the issued claims literally; strong § 103/background art for the bag-in-rigid-cartridge structure. (Note: a related Chinese-family document — CN2701632Y — expressly cites US4558326 for pressurizing ink between a bag and a rigid case, confirming this reference's role as the canonical bag-in-rigid-box teaching.)

3.2 US 4,575,738 A — transient suppressor

• Full citation: U.S. Patent No. 4,575,738, "Ink jet printing apparatus having an ink pressure transient suppressor system," Tektronix, Inc.
• Dates: filed 1984-07-20; granted 1986-03-11
• Disclosure (title/bibliographic level; full text not retrieved this session): A compliant/accumulator element that damps pressure transients in an ink-jet ink supply.
• Potential § 102 relevance: Discloses pressure-damping/compliant-element concepts, i.e., art bearing on the "resilient" aspect in the abstract. It is in a different architecture (continuous/multi-deflection ink jet) and does not disclose the claimed air-container-forcing-ink structure. Anticipation: none.

3.3 US 4,982,200 A — fluid jet printing device

• Full citation: U.S. Patent No. 4,982,200, "Fluid jet printing device," Swedot System Ab.
• Dates: filed 1985-06-13; granted 1991-01-01
• Disclosure (title level): A fluid-jet (continuous ink jet) printing device; per the earlier obviousness taxonomy, a general pressurized-delivery/purge-type system.
• Potential § 102 relevance: General-purpose background in pressurized ink delivery; no resilient expanding air container, no cartridge-interior air-bladder forcing ink. Anticipation: none.

3.4 US 4,734,711 A — the "expanding bag membrane" reference

• Full citation: U.S. Patent No. 4,734,711, "Pressure regulation system for multi-head ink jet printing apparatus," Eastman Kodak Company (Piatt et al.).
• Dates: filed 1986-12-22; granted 1988-03-29
• Disclosure (verified): A pressure-regulation assembly in which each chamber carries a bag-shaped pliant membrane clamped around its periphery that "is sized to substantially fill its chamber in its fully expanded condition and is shaped to fold upon itself when collapsed," responding to pressure differentials across it; a common pressure reservoir serves all heads so their print-head pressures equalize at a nominal value.
• Potential § 102 relevance: This is the cited art's best disclosure of the "resilient container that expands under pressure" physical structure (so it is central to the § 103 case for claim 1's element 4). But its membranes regulate pressure in a continuous multi-head circulation system, not an air bladder in a replaceable cartridge forcing ink out an ink outlet. Anticipation: none of the issued claims; strong § 103 art for the "expanding resilient container" element.

3.5 US 5,446,486 A — liquid-jet printer device

• Full citation: U.S. Patent No. 5,446,486, "Liquid-jet printer device," Markpoint System Ab.
• Dates: filed 1989-12-12; granted 1995-08-29
• Disclosure (title level): General liquid-jet printer device.
• Potential § 102 relevance: Background only. Anticipation: none.

3.6 US 5,453,770 A — on-demand print head

• Full citation: U.S. Patent No. 5,453,770, "On-demand type ink jet print head," Seiko Epson Corporation.
• Dates: filed 1991-06-13; granted 1995-09-26
• Disclosure (title level): An on-demand (drop-on-demand) ink-jet print head.
• Potential § 102 relevance: Print-head structure; supports the "ink jet printer" element of claim 19 and general context. No cartridge air-container teaching. Anticipation: none (relevant only to the claim-19 "ink jet printer" identification, which the cited references elsewhere supply too).

3.7 US 5,757,390 A — ink volume sensing/replenishing

• Full citation: U.S. Patent No. 5,757,390, "Ink volume sensing and replenishing system," Hewlett-Packard Company.
• Dates: filed 1992-08-12; granted 1998-05-26
• Disclosure (title level; full text not retrieved this session): An off-axis/large-capacity supply with ink-volume sensing and replenishment (per the earlier taxonomy: stationary/carriage-reservoir architectures and riser/air-vent structures).
• Potential § 102 relevance: Corroborates the off-axis, high-capacity problem/context and venting of reservoirs; no resilient air container forcing ink. Anticipation: none.

3.8 US 5,877,793 A — external reservoir refill

• Full citation: U.S. Patent No. 5,877,793, "Automatic ink refill system for disposable ink jet cartridges," ColorSpan Corporation (Erickson, Paul R.).
• Dates: priority 1993-10-20 (a continuation chain; this grant filed 1997-11-18); granted 1999-03-02
• Disclosure (verified): A disposable ink-jet cartridge (print head + ink supply container at sub-atmospheric pressure) removably mounted on a traversing carriage; an external reservoir off the carriage replenishes it through flexible supply tubing during printing, while preserving the cartridge's negative-pressure hydrodynamic condition.
• Potential § 102 relevance: Directly addresses the '115 Background problem (cost per page / intervention interval via off-axis supply). It teaches external-reservoir replenishment, not pump-driven, resilient-air-container ink expulsion. Anticipation: none.

3.9 US 5,870,124 A — pressurizable cartridge with flexible-walled ink vessels

• Full citation: U.S. Patent No. 5,870,124, "Pressurizable liquid ink cartridge for coincident forces printers," Eastman Kodak Company (inventor Kia Silverbrook).
• Dates: priority 1995-04-12; filed 1996-12-03; granted 1999-02-09 (EP counterpart EP0765242A1 published 1997-04-02)
• Disclosure (verified from text and abstract): A removable cartridge consisting of a rigid box containing ink vessels that include at least one flexible surface; the box is "sealed to the atmosphere" with an ink outlet to the supply manifold and a control-pressure inlet connected to a pressurizing device. A single pressurizing system pressurizes the fluid (preferably air) surrounding all ink vessels inside the cartridge; because each vessel has a flexible membrane, that surrounding pressure is transmitted to the ink. Claim 1 requires a predetermined positive pressure (≥2% above ambient).
• Potential § 102 relevance: The closest cited reference for the cartridge-with-interior / air-inlet / ink-outlet / flexible ink vessel combination and for hermetic sealing ("sealed to the atmosphere"), and it teaches air as the pressure medium. It does not disclose a discrete resilient air container that itself expands to force ink out — the pressure acts on the vessel's flexible wall directly. Anticipation: none of the issued claims literally (fails the resilient-expanding-air-container element); very strong § 103 primary/secondary art and the best § 102 near-miss alongside US6030074A.

3.10 US 5,877,795 A — purging air from ink tubes

• Full citation: U.S. Patent No. 5,877,795, "Methods and designs to purge air from ink tubes during initial startup," Hewlett-Packard Co.
• Dates: filed 1996-05-24; granted 1999-03-02
• Disclosure (title level; full text not retrieved this session): Startup purging of air from ink-delivery tubing.
• Potential § 102 relevance: Evidences that air in the ink path is a recognized defect — motivation evidence (relevant to § 103, not anticipation). No resilient air container. Anticipation: none.

3.11 US 6,030,074 A — the examiner-cited "pressurized bag-in-rigid-container" reference (most relevant)

• Full citation: U.S. Patent No. 6,030,074, "Method and apparatus for delivering pressurized ink to a printhead," Hewlett-Packard Company (Barinaga, John A.). Examiner-cited ("*") on the face of '115.
• Dates: priority 1996-07-15 (continuation filed 1997-12-10); granted 2000-02-29. Because it granted within one year before the '115 filing (2000-03-09), it is at minimum § 102(a) art as of its grant and § 102(e) art as of its 1996-07-15 filing.
• Disclosure (verified): An apparatus for delivering pressurized ink to a printhead comprising a deformable ink bag, an air-impermeable rigid pressurizable container substantially surrounding the bag that exerts fluid pressure on the bag, and a sealable ink outlet port connectable to the printhead. An air compressor feeds air through a gas inlet port into the chamber between the rigid container and the bag; a ball-and-spring bleed vent relieves pressure above about 2 psi; the bag is a multi-layer metallized polymer film that "collapses when its contents are emptied"; ink flows through a sealable outlet port and conduit to a print cartridge having a pressure regulator. The container is explicitly "a rigid container."
• Mapping to claim 1: cartridge interior ✓; air inlet (gas inlet port 55) ✓; ink outlet (outlet port 25 / conduits) ✓; air pump (compressor) creating positive pressure ✓; ink source in the interior in fluid communication with the outlet (deformable bag) ✓. Sole missing element: the "resilient air container" — '074's outer container is rigid, so the expansion that squashes the ink bag is not performed by a resilient chamber.
• Potential § 102 relevance: The single most on-point reference. It discloses claims 3 and 4 (resilient/bag ink source) and the claim-7 geometry ("substantially surrounding the bag"), plus the claim-5/16 vent concept (a bleed vent) and the claim-19 ink-jet context. But because it uses a rigid outer container, it does not literally anticipate claims 1, 9, or 15, nor any dependent claim that incorporates their resilient-air-container element. Anticipation: none of the issued claims literally; the strongest single-reference starting point for a § 103 challenge.

3.12 US 5,719,609 A — redundant sealing of a print-head pressure regulator

• Full citation: U.S. Patent No. 5,719,609, "Method and apparatus for redundant sealing of a printhead pressure regulator," Hewlett-Packard Company.
• Dates: filed 1996-08-22; granted 1998-02-17
• Disclosure (title level; full text not retrieved this session): Sealing of an on-board print-head pressure regulator.
• Potential § 102 relevance: Pressure-regulator/sealing background; no air-bladder-forcing-ink structure. Anticipation: none.

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4. § 102 mapping summary

Net finding: On a strict § 102 reading, none of the 12 references cited on the face of US 6,243,115 anticipates any of the 19 issued claims, because each independent claim (and therefore every dependent claim) requires the resilient, pump-inflated air container that expands to force ink through the outlet — a limitation that no cited reference discloses. The references are, however, individually and collectively potent § 103 material, exactly as the prior obviousness section concluded, with US6030074A + US5870124A (and/or US4734711A) as the strongest combinations.

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5. An important cross-reference caveat — the most relevant prior art is not on the face of the patent

Building on, rather than repeating, the PTAB section: the ground the Board actually instituted in IPR2020-01085 was anticipation/obviousness over Childers (US 6,116,723) and obviousness over Childers + Buck (US 4,500,895) — references that do not appear in the 12 patent citations reproduced on the face of '115. If the question is "most relevant prior art" in the practical, litigation sense, Childers US 6,116,723 is the reference to lead with, not the 12 examiner citations. The one reference the examiner did cite (US6030074A, HP) is also the one closest to the claimed subject matter — a useful sanity check, but it still misses the resilient-air-container limitation. There was no Final Written Decision in IPR2020-01085 (terminated-settled 2021-03-29), so none of this art has been adjudicated on the merits.

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6. Bottom line

1. Identity: 6243115 = US 6,243,115 B1, Lexmark/Lexmark-inkjet, filed 2000-03-09, granted 2001-06-05. No other patent shares this number.
2. The 12 cited references are all § 102(b) art (published more than one year before the 2000-03-09 filing) except US6030074A, which granted 2000-02-29 and is therefore § 102(a)/§ 102(e) art.
3. No cited reference anticipates the issued claims under § 102, because each independent claim (1, 9, 15) and every dependent claim requires a resilient air container that expands under pump pressure to force ink out — absent from all 12.
4. Most relevant cited art: US6030074A (examiner-cited; rigid-container bag-in-box with compressor and ~2 psi bleed vent) is the closest single reference, followed by US5870124A (flexible-walled, sealed, pressurizable cartridge) and US4558326A (rigid cartridge + flexible bag + gas pressurization). US4734711A supplies the expanding-bladder structure.
5. Most relevant overall art (not on the patent face): Childers US 6,116,723 and Buck US 4,500,895, the instituted-but-unadjudicated IPR2020-01085 grounds.

Confidence notes: Descriptions for US4558326A, US6030074A, US5870124A, US4734711A, and US5877793A are grounded in retrieved full text/abstracts and bibliographic records. Descriptions for US4575738A, US4982200A, US5446486A, US5453770A, US5719609A, US5757390A, and US5877795A rest on title-level and citation-table information only (searches returning full text hit the session step limit); their § 102 conclusions ("no anticipation") follow from their titles and architectures and would not change on fuller review, but the characterizations should be treated as provisional. Dates are as printed on the face of the '115 citation table and corroborated where full text was retrieved; no identifiers were altered.

Obviousness Analysis — U.S. Patent 6,243,115 B1 (35 U.S.C. § 103)

This analysis builds on the previously generated patent summary and litigation summary (which are incorporated by reference) and does not repeat them. It evaluates only whether the claims of the '115 patent would have been obvious at the March 9, 2000 effective filing date, using the 12 prior-art references listed in the patent's own citations (the "Prior Art" section of the record). A procedural caveat first: the inter partes review of this patent (IPR2020-01085, HP Inc. v. Slingshot Printing LLC) was instituted on January 14, 2021, but was terminated by settlement on March 29, 2021 without a final written decision. The grounds below are therefore this analyst's independent § 103 assessment, not a reconstruction of any PTAB holding, and no estoppel or merits finding exists in the record.

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I. Legal framework applied

Under pre-AIA § 103 (the law applicable to this pre-AIA patent in any post-grant challenge) 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 to a person having ordinary skill in the art (PHOSITA) at the time of invention. Under Graham v. John Deere and KSR International Co. v. Teleflex Inc., obviousness may be shown by a combination of known elements yielding a predictable result, an "obvious to try" selection from a finite set of known options, or a design need/known problem providing the reason to combine. An explicit teaching, suggestion, or motivation in the references is not required; the analysis may rely on the knowledge of the PHOSITA and the inferences a skilled artisan would draw.

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II. Person of ordinary skill in the art

A PHOSITA in early 2000 would have had a B.S. in mechanical, chemical, or systems engineering (or equivalent experience), with roughly 2–5 years designing ink-jet ink-delivery architectures: on-carriage and off-axis ink supplies, collapsible-bag/box ("bag-in-box") reservoirs, air pumps and compressors, pressure regulators and bleed vents, and fluidic interconnects (needle/septum, quick disconnects). The person would be familiar with the well-known design objectives recited throughout the cited art: low cost per page, high ink capacity, constant delivery pressure over the life of the supply, removal of air from ink lines, and minimization of unusable ("wasted") ink.

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III. Taxonomy of the cited prior art

The twelve references cited on the face of the '115 patent sort naturally into functional groups:

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IV. The dispositive claim limitation

Claim 1 (and its means-plus-function counterpart claim 9 and method counterpart claim 15) require four structural features:

1. a printer cartridge with an interior, an air inlet, and an ink outlet;
2. an air pump connected to the air inlet creating positive pressure in the interior;
3. an ink source (ink in the interior) in fluid communication with the ink outlet; and
4. a resilient air container in the interior, in fluid communication with the air inlet, which expands under the positive pressure and forces the ink through the ink outlet.

The claimed "printer cartridge" is not limited to a printhead-carrying pen. The '115 specification itself states the cartridge "can also be embodied as a separate ink tank or ink cartridge that attaches within a printer separately from one or more other printer cartridges." That is precisely the form of the off-axis "ink supply" in Group A–D references. Elements 1–3 are ubiquitous in Groups A and B. Element 4 — the discrete resilient (e.g., bag) air container that inflates to squeeze the ink out — is the only meaningful point of contention, and it is the focus of the combinations below.

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V. Combination 1 — US6030074A in view of US5870124A (claims 1–5, 9–12, 15–16, 19)

US6030074A as primary reference. HP's '074 discloses, in terms nearly identical to the '115 problem statement, an apparatus for delivering pressurized ink to a printhead comprising: a deformable bag for holding ink; a pressurizable container substantially surrounding the bag for exerting fluid pressure on the bag; and a sealable ink outlet port in fluid communication with the bag, connectable to the printhead. Air is supplied by an air compressor (pump), plumbed through an air manifold into the chamber between the rigid outer container and the ink bag; a ball-and-spring bleed vent relieves pressure above ~2 psi. US6030074A's claim 1 additionally shows the ink supply feeding a print cartridge through an ink supply tube and a pressure regulator.

Mapping to claim 1: the rigid container is a "printer cartridge having an interior" (the chamber); the air conduit into the chamber is "at least one air inlet"; the bag outlet port/ink supply tube is "at least one ink outlet"; the compressor is "an air pump connected to the air inlet for creating a positive pressure in the interior"; and the deformable ink bag is "an ink source … in fluid communication with the ink outlet." The only element not literally present is the resilient air container: in '074 the air is pumped directly into the rigid container chamber, which collapses the ink bag, rather than into an inflatable bladder.

US5870124A supplies the missing concept. Kodak's '124 discloses a sealed outer box cartridge containing ink vessels having "at least one flexible or movable surface adapted to transfer pressure from the pressurizing medium to ink," with the pressurizing medium (preferably air) admitted through a control-pressure inlet and the ink exiting through an ink outlet. It teaches that a single pressurizing system can serve multiple ink vessels in one cartridge. The combination of '074's pump-driven bag-in-box and '124's flexible-vessel, pressure-inlet/outlet cartridge teaches a skilled artisan to place the pressurized air behind a flexible boundary so that air pressure is translated into a mechanical squeeze on the ink — the identical pressure-transfer mechanism claimed by the '115 patent.

Why a PHOSITA would combine them:

• Same field and same problem. Both references address delivering positively pressurized ink from a replaceable, off-axis supply to an ink-jet printhead while maintaining a regulated pressure (1–2 psi in '074; predetermined positive pressure in '124). Combining them is the integration of two solutions to the same problem, not a leap.
• Predictable result and finite options. The '115 specification itself concedes the resilient container is "preferably … a bag" and that the air container may sit within, next to, or around the ink container — i.e., the inventor's own contribution is selecting among a handful of known bag/bladder arrangements, the textbook "obvious to try" scenario under KSR. '074 already uses a deformable bag as the ink container; using an identical resilient bag as the air container (or making '124's flexible vessel boundary into a discrete inflatable bladder) requires only conventional material and geometry choices.
• Recognized motivation to isolate air from ink. HP's own '7795 (purge air from ink tubes at startup) and '7390 (riser/air-vent structures) show that air in the ink path is a known source of print defects and startup failures. A PHOSITA reading '074 (air directly against the bag exterior) would be motivated to interpose a resilient air container so that the compressed air never contacts the ink, while a cartridge vent (claim 5 / method claim 16) prevents "deleterious pressurization" — exactly the rationale stated in the '115 specification for the resilient-air-container embodiments of Figures 2–4.
• No teaching away. '074's statement that its approach requires "no … additional pressurization devices" refers to spring/bladder mechanisms inside the printhead of the prior HP pens. Placing a resilient air container in the off-axis ink supply does not reintroduce the criticized printhead device and is not disparaged by either reference.
• Claim 2 (hermetic sealing). Both '074 (sealed pressurizable container) and '124 ("sealed to the atmosphere" box with only the inlet and outlet) teach a cartridge whose only openings are the air inlet and ink outlet.
• Claims 3–4 (ink source is a resilient container / bag). Disclosed verbatim by '074's "deformable bag."
• Claim 5 / claim 16 (air vent). With a resilient air container isolating the pressure, venting the cartridge interior (as in Figures 3–4 of '115) is the routine engineering response to prevent pressure buildup; '124's sealed-box-with-medium and HP's vented reservoirs provide the background.
• Claims 9–12, 15, 19. The means-plus-function claims (9–12) read on the identical structures ('074's compressor and bag; '124's cartridge), and the method claim 15 merely recites the operation of that combined apparatus (place cartridge, pressurize the resilient container, squeeze ink out, print) — the method adds no separate inventive act. Claim 19 (ink-jet printer) is inherent in the references.

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VI. Combination 2 — US5870124A in view of US4734711A (claims 1, 6, 9, 13, 17)

US5870124A as primary. Kodak's '124 supplies the cartridge-with-interior/air-inlet/ink-outlet and the ink vessels with flexible pressure-transfer surfaces, and it expressly contemplates air as the pressurizing medium — a near-complete anticipation of claim 1 except for a discrete resilient air container that expands.

US4734711A supplies the expanding-bladder structure. Eastman Kodak's '4711 discloses expandable and collapsible bag-shaped membrane/bladder elements seated in chambers, which "substantially fill [the] chamber in [their] fully expanded condition" and "fold upon [themselves] when collapsed," responding to fluid pressure differentials across them (there, to regulate printhead pressures to a common nominal value). The bladder is thus a "resilient air container in the interior … expanding from the positive pressure" — the very structure of '115 claim 1's element 4 (and Figures 2 and 4 of '115, where the air container sits in or beside the ink).

Why a PHOSITA would combine them:

• Filling a known gap with a known part. If a designer wanted to pressurize the ink of '124 without placing air in direct contact with ink (or without requiring a fully hermetic cartridge), the natural expedient is a bladder of the type in '4711 — an inflatable, resilient separator whose expansion displaces the ink. Both patents are Kodak; a skilled artisan would be aware of the bladder technology across Kodak's ink-jet program.
• Constant-pressure objective. '4711's entire purpose is maintaining a stable nominal pressure; the '115 specification identifies "constant pressure … over the life of the printer" as a desideratum. Combining '124's pressurized cartridge with '4711's bladder regulator directly serves that goal.
• Claim 6 / claim 13 / claim 17 (air container positioned within the ink source container). The '115 Figure 4 configuration — a bladder inside the ink bag — is achieved by taking '124's flexible ink vessel and '4711's expandable bladder and nesting one inside the other. Collapse/evacuation of flexible ink containers by an internal expanding member was a conventional dispensing technique, and the "finite known options" (inside/next to/encapsulating) are all structural permutations a designer would try.
• Claims 9, 13, 17 fail for the same reasons under their means-plus-function and method forms.

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VII. Combination 3 — US6030074A with routine substitution of a resilient outer container (claims 7–8, 14, 18)

Claims 7, 8, 14, and 18 require the resilient air container to encapsulate the ink source container (the Figure 3 embodiment of '115). US6030074A already discloses the encapsulating geometry: "a pressurizable container substantially surrounding the bag." The sole difference is that '074's outer container is rigid, while claims 7/14 require the outer (air) container to be resilient.

That substitution would have been obvious:

• The outer container's only functions in '074 are to confine the air and transmit its pressure to the bag — functions a resilient bag performs equally well, as demonstrated by the pervasive use of resilient bags for both ink and air in the very same field ('074's own deformable ink bag; '124's flexible vessels; '7390's collapsible reservoirs). Selecting an elastomeric/film bag for a container that the art already forms from the same class of materials is an obvious material choice with a predictable result.
• The '115 dependent claims add nothing inventive: claim 8 ("the resilient air container is a bag") merely names the most conventional embodiment of "resilient container," and claim 18 is the corresponding method step.

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VIII. Supporting motivation from the off-axis references (US5757390A and US5877793A)

The '115 specification's Background identifies the problem the invention addresses: single disposable cartridges produce high cost per page and short user-intervention intervals, while placing large ink supplies on the moving carriage is impractical. The cited HP '7390 (off-board ink supply replenishing a carriage-borne reservoir through a conduit) and Colorspan '7793 (external reservoir refilling a carriage cartridge while preserving its hydrodynamic backpressure) are the principal prior responses to that same problem. In any ground where claim scope is read against the specification's off-axis "ink tank" embodiment, these references reinforce the motivation to combine: a skilled artisan building an economical, high-capacity, pump-fed delivery system (as in '074) would look directly to the off-axis architectures of '7390/'7793. Neither reference is strictly necessary to invalidate claims 1–19, but both corroborate that each element of the claimed system was individually known and that combining them served the recognized design needs of cost, capacity, and intervention interval.

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IX. Overall assessment

The weakest limitation across all grounds is claim 1's requirement that the resilient air container itself expand to force ink out, because the closest reference (US6030074A) deliberately uses a rigid outer chamber. However, under KSR's "obvious to try" and predictable-variation analysis — and given that the '115 specification itself concedes the air container is simply a "resilient container, such as a bag," arranged in one of three known positions — a PHOSITA would have had ample reason to substitute or insert an inflatable resilient bladder, whether to isolate air from ink, permit a vented cartridge, or achieve uniform evacuation. That reasoning, applied to the examiner-cited US6030074A in combination with US5870124A and/or US4734711A, would render claims 1–19 obvious under § 103.

Secondary considerations: No objective indicia of non-obviousness (long-felt need, commercial success, copying, skepticism) appear in the record before me, and the settlement-terminated IPR2020-01085 produced no final written decision that would inform or estop this analysis.

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Sources grounding the reference characterizations: Google Patents/Espacenet records for US6030074A (espacenet.com biblio; patents.google.com/patent/US6030074) confirming the deformable bag, pressurizable surrounding container, compressor, ~2 psi bleed vent, and ink supply tube; EP0765242A1/patents.google.com record for US5870124A confirming the sealed box, flexible-surface ink vessels, single pressurizing system, and air as pressurizing fluid; US4734711A (uspto.report/patent/grant/4734711; patents.google.com/patent/US4734711) confirming the expandable/collapsible bag-shaped membranes; and FreePatentsOnline/Unified Patents records for US5877793A and US5757390A confirming the external-reservoir replenishment architectures. No patent numbers or identifiers were altered in this analysis.