US 7938523

Search verification

I searched for the specific number 7938523 (and its PTAB/CAFC litigation dockets). All results confirmed the correct patent — U.S. Patent No. US7938523B2, Application No. 11/762,101 — and I did not conflate it with similarly numbered patents. The USPTO/PTAB materials (e.g., the IPR2022-01416 record) repeatedly identify "U.S. Patent No. 7,938,523," Application No. 11762101, titled "FLUID SUPPLY TANK VENTILATION FOR A MICRO-FLUID EJECTION HEAD" (source: ptacts.uspto.gov document download; portal.unifiedpatents.com IPR case page).

Concise patent summary

Title: Fluid supply tank ventilation for a micro-fluid ejection head

Inventor: Charles Stanley Aldrich (sole inventor; Nicholasville, KY per PTAB records)

Assignee history (per assignment records / Google Patents):

• Original assignee: Lexmark International, Inc. (assignment recorded June 13, 2007)
• Later: Funai Electric Co., Ltd. (assignment effective April 1, 2013)
• Current listed assignee: Slingshot Printing LLC (assignment effective March 29, 2019)

Filing date: June 13, 2007 (U.S. Application No. 11/762,101, utility under 35 U.S.C. § 111(a))

Issue date: May 10, 2011

Legal status: Active (Google Patents shows adjusted expiration of March 7, 2030; maintenance fees paid through the 12th year).

Abstract (verbatim): "An improved fluid supply tank for a micro-fluid ejection head and method for improving operation of a micro-fluid ejection device. The fluid supply tank has a body portion for holding a fluid to be ejected. The body portion includes a fluid exit port on an exit end thereof and a cover on an opposing end thereof. An internal vent conduit is disposed in the tank between the exit end and the cover for air removal adjacent to the exit port."

Technology in brief: The patent addresses trapped air adjacent to the connection between a replaceable ink/fluid supply tank and a micro-fluid ejection (printhead) structure. When trapped air expands or contracts (due to altitude or atmospheric pressure changes, tank swapping, etc.), it can cause nozzle seepage, air ingestion, or cross-contamination in multi-color systems. The solution is an internal vent conduit inside the tank running between the exit-port end and the top cover, which has a serpentine atmospheric vent. Air near the exit port is channeled around the capillary felts and out through the cover vent, avoiding the need for large air-collection volumes or purge/maintenance stations. Dimensions of ~0.5–2 mm (width and depth), optional hydrophobic/hydrophilic coatings, and disposable-head embodiments are described.

Plain-language overview of the independent claims

There are 18 claims total; the independent claims are claim 1 (apparatus) and claim 10 (method).

Claim 1 — Fluid supply tank (apparatus):
Requires (a) a tank body holding fluid, having a fluid exit port at its exit end and a cover at the opposite end, where the cover has an opening open to the atmosphere; (b) an internal vent conduit running between the exit end and the cover, for removing air near the fluid exit port and releasing it through the cover to the atmosphere; and (c) an air space in the fluid exit port, with the vent conduit in air-flow communication with both that air space and the cover.
Plain meaning: An ink tank with an internal air channel built in from near the outlet port up to a top cover that vents to outside air, so air trapped at the outlet can escape to the atmosphere instead of disturbing printhead fluid pressure.

Claim 10 — Method of enhancing operation of a micro-fluid ejection device:
Requires (a) disposing an internal vent conduit in a fluid supply container, in air-flow communication between an air space at the container's fluid-exit end and the container cover (opposite the exit end, with an opening to the atmosphere); and (b) installing the container on the micro-fluid ejection device so trapped air between container and device is urged through the internal vent conduit and out through an atmospheric vent in the cover.
Plain meaning: A method of fitting/installing a vented fluid container so any air trapped at the container/device interface is pushed through an internal channel and exhausted through the top cover's atmospheric vent.

Related proceedings (relevant to CAFC/USPTO docket searches)

• IPR2022-01416 — Canon U.S.A., Inc. and Canon Inc. v. Slingshot Printing LLC, PTAB. Petition filed August 23, 2022; institution granted April 13, 2023; Final Written Decision issued April 9, 2024; Director Review denied June 6, 2024. Per the hearing transcript, the dispute centered on whether the prior-art "Studer '708" reference's vent conduit anticipated the "internal vent conduit … removing air adjacent to the fluid exit port" limitation of the independent claims. Status is listed as "Final Written Decision Appealed."
• CAFC Appeal 24-2132 — Slingshot Printing LLC v. Canon U.S.A., Inc. / Canon Inc. Docketed July 26, 2024; oral argument held May 6, 2026; the CAFC website lists a nonprecedential Rule 36 judgment posted on or about May 7, 2026, affirming the PTAB decision (source: cafc.uscourts.gov notice for 24-2132). IPWatchdog reporting characterizes the underlying PTAB final written decisions as finding Slingshot claims unpatentable as obvious.

Uncertainty notes

• Date discrepancy: Your prompt states "Current Date: April 26, 2026," but the live CAFC website search results show the Rule 36 judgment in 24-2132 was posted May 7, 2026 — after that date. Per the operating rule that live search results are ground truth, I am reporting the May 2026 posting; please reconcile the apparent date mismatch on your end.
• I confirmed that a Final Written Decision and Rule 36 affirmance exist, but I did not retrieve the full FWD text within these searches, so I cannot state with certainty the exact claim-by-claim unpatentability outcome (which specific claims of the 18 were cancelled) or the precise grounds (anticipation vs. obviousness) for every claim.
• The Rule 36 judgment is a summary affirmance without opinion; the "Unified Patents" and Justia docket pages confirm case number 24-2132 and party/attorney details (Mark Borsos for Slingshot; Dion Bregman for Canon).

Key sources: patents.google.com/patent/US7938523B2; freepatentsonline.com/7938523.html; ptacts.uspto.gov IPR2022-01416 records; portal.unifiedpatents.com/ptab/case/IPR2022-01416; cafc.uscourts.gov (24-2132 Rule 36 judgment, May 7, 2026); dockets.justia.com/docket/circuit-courts/cafc/24-2132.

Known Litigation Involving U.S. Patent No. 7,938,523 (US7938523B2)

Based on live searches of the Unified Patents litigation portal, PTAB records (including USPTO § 290 / AO-120 notices filed in the IPR2022-01416 record), PACER-derived dockets (PacerMonitor, DocketAlarm, CourtListener, UniCourt), and the CAFC docket, the following proceedings involve the '523 patent. All references below were verified to the specific patent number 7,938,523 (App. No. 11/762,101); I did not include cases that only involve other Slingshot patents (e.g., 2:22-cv-01852 "Slingshot II," which asserts 7,290,864 / 7,594,708 / 7,484,823 but not the '523 patent).

1. Slingshot Printing LLC v. HP Inc. — W.D. Tex. (Waco), then Austin

• Case No.: 6:19-cv-00362-ADA (Waco Division); continued as 1:20-cv-00184-ADA (Austin Division)
• Filed: June 11, 2019 (Waco); Austin case filed February 19, 2020
• Plaintiff: Slingshot Printing LLC
• Defendant: HP Inc.
• Patents: Multi-patent action asserting at least 6,243,115; 6,394,593; 6,817,707; 7,258,434; and 7,938,523 (confirmed by AO-120 forms in the PTAB record)
• Status/Outcome: The Waco case was transferred (stipulation to transfer venue to the Austin Division, filed ~Feb. 18, 2020). The Austin case (1:20-cv-00184-ADA) was dismissed with prejudice by order dated April 1, 2021, pursuant to a stipulated dismissal reflecting a Settlement, Release and License Agreement (court retained jurisdiction to enforce the settlement). Unified Patents lists 6:19-cv-00362 as Closed.
• Sources: portal.unifiedpatents.com/litigation/Texas Western District Court/case/6:19-cv-00362; AO-120 forms in ptacts.uspto.gov IPR2022-01416 exhibit downloads; insight.rpxcorp.com venue briefing.

2. Slingshot Printing LLC v. Canon U.S.A., Inc. and Canon Solutions America, Inc. — E.D.N.Y.

• Case No.: 2:22-cv-00123 (JMA)(AYS), later (HG)(LGD), then (NJC)(LGD)
• Filed: January 7, 2022
• Plaintiff: Slingshot Printing LLC
• Defendants: Canon U.S.A., Inc. and Canon Solutions America, Inc. (corporate parent Canon Inc. identified in disclosures)
• Patents: Slingshot asserted four patents: 7,938,523, 7,195,341, 7,559,629, and 7,152,951. Canon counterclaimed for declaratory judgments of invalidity and noninfringement of all four, including the '523 patent.
• Status/Outcome: Stayed December 1, 2022 pending resolution of the IPRs Canon filed against the asserted patents. After the PTAB's Final Written Decision in IPR2022-01416 (April 9, 2024), the docket reflects termination around late 2024, with only administrative activity (e.g., counsel withdrawal in May 2025) thereafter. I could not confirm from the public sources retrieved the precise terminating document (e.g., stipulated dismissal vs. judgment); that detail would need PACER confirmation.
• Sources: DocketAlarm patent search (patent:7938523); courtlistener.com/opinion/9842293; unicourt.com/case/pc-db5-...; pacermonitor.com/public/case/43190047; IPWatchdog Patent Filings Roundup (Jan. 13, 2022) listing 2:22-cv-00123 against Canon with patent 7938523 among those asserted.

3. Canon U.S.A., Inc. and Canon Inc. v. Slingshot Printing LLC — PTAB (IPR2022-01416)

• Proceeding: IPR2022-01416 (Patent 7,938,523)
• Petition filed: August 23, 2022
• Petitioners: Canon U.S.A., Inc. and Canon Inc.
• Patent Owner: Slingshot Printing LLC
• Institution: Granted April 13, 2023
• Final Written Decision: April 9, 2024 (hearing transcript confirms the dispositive dispute was whether the "Studer '708" prior-art reference's vent conduit met the "internal vent conduit … removing air adjacent to the fluid exit port" limitation; Patent Owner did not dispute any other limitation of the independent claims). The FWD found the challenged claims unpatentable.
• Director Review: Denied June 6, 2024
• Status: "Final Written Decision Appealed" (per Unified Patents); now affirmed on appeal (see item 4).
• Sources: portal.unifiedpatents.com/ptab/case/IPR2022-01416; DocketAlarm IPR2022-01416 docket; ipverse.greyb.com PTAB case page; PTAB hearing transcript (Jan. 24, 2024).

4. Slingshot Printing LLC v. Canon U.S.A., Inc. and Canon Inc. — U.S. Court of Appeals for the Federal Circuit

• Case No.: 24-2132
• Appeal docketed: July 26, 2024
• Appellant: Slingshot Printing LLC (Mark Borsos / Fitch Even; argued by Kayvon Ghayoumi, MoloLamken)
• Appellees: Canon U.S.A., Inc. and Canon Inc. (argued by Julie S. Goldenberg, Morgan Lewis)
• Nature: Appeal from the PTAB in IPR2022-01416 (the '523 patent)
• Status/Outcome: Oral argument was held May 6, 2026. Per the CAFC's docket/opinions page, a nonprecedential Rule 36 judgment was entered May 7, 2026, AFFIRMING the PTAB's Final Written Decision (per curiam: Moore, C.J., Stoll and Stark, JJ.).
• Sources: cafc.uscourts.gov/opinions-orders/24-2132.RULE_36_JUDGMENT.5-7-2026_2690104.pdf; dockets.justia.com/docket/circuit-courts/cafc/24-2132; courtlistener.com oral-argument audio listing for 24-2132.

Summary table

Caveats and notes

• Date discrepancy: Your stated current date (April 26, 2026) precedes the CAFC Rule 36 judgment date (May 7, 2026) shown on the live CAFC docket. Per your operating rule that live search results are ground truth, I have reported the Rule 36 affirmance as reflected in those results; you may wish to reconcile the date on your end.
• FWD specifics: I confirmed the IPR2022-01416 Final Written Decision issued April 9, 2024 and was affirmed, but I did not retrieve the full FWD text, so I cannot state with certainty the exact claim-by-claim outcome (which of the 18 claims were cancelled) or whether each ground was anticipation or obviousness.
• E.D.N.Y. termination: The exact final disposition document in 2:22-cv-00123 (and whether it post-dated the IPR FWD) was not visible in the sources retrieved; PACER would confirm.
• W.D. Tex. relationship: The record indicates the Waco case (6:19-cv-00362) was transferred/refiled in Austin as 1:20-cv-00184-ADA, which is where the April 1, 2021 stipulated dismissal with prejudice was entered. Both docket numbers appear in the USPTO § 290 notices and in the Unified Patents/Google Patents litigation lists.
• No other U.S. district-court cases or IPRs naming the '523 patent appeared in the searches I ran (DocketAlarm's patent:(7938523) search surfaced the E.D.N.Y. Canon case and IPR2022-01416, plus the PTAB/docket records above).

Proceedings overview

Web search confirms one AIA trial proceeding on U.S. Patent No. 7,938,523: IPR2022-01416 (Canon v. Slingshot Printing). Flag on the data-source discrepancy: the structured "PTAB proceedings on file" block (USPTO Open Data Portal ingest) reports no AIA trial proceedings, but that is stale/incomplete — the USPTO/PTAB record, Unified Patents, DocketNavigator/Docket Alarm, and the CAFC docket all confirm IPR2022-01416 exists, was instituted, produced a Final Written Decision on 2024-04-09, and was affirmed by the Federal Circuit on 2026-05-07. Breakdown by status: 0 active / 1 claims-invalidated (FWD issued and affirmed) / 0 sustained / 0 settled / 0 institution-denied. Bottom line for a defendant: both independent claims (1 and 10) and every substantive dependent claim challenged (2, 3, 5–7, 11, 12, 14–16) have been canceled and the cancellation affirmed on appeal — the only claims left on paper (4, 8, 9, 13, 17, 18) are dependent on the canceled independent claims, so this patent is effectively dead and any demand letter built on claims 1 or 10 has no viable infringement theory.

IPR2022-01416 — Canon U.S.A., Inc. and Canon Inc. v. Slingshot Printing LLC

• Type: Inter Partes Review
• Filed: 2022-08-23
• Status: "Final Written Decision Appealed" (Unified Patents/PTAB record); plain-English gloss — the FWD issued 2024-04-09, Patent Owner's Director Review was denied 2024-06-06, and the Federal Circuit affirmed via Rule 36 judgment on 2026-05-07, so the unpatentability determination is now final.
• Judge panel: Jo-Anne M. Kokoski (author judge), Garth D. Baer, and John D. Hamann, Administrative Patent Judges (per hearing transcript and filings).
• Petition grounds (challenged claims: 1–3, 5–7, 10–12, and 14–16 — independent apparatus claim 1, independent method claim 10, and their substantive dependents; claims 4, 8, 9, 13, 17, 18 were not challenged):
  • Ground 1 — § 102 anticipation by U.S. Patent No. 6,739,708 B2 ("Studer '708"): claims 1, 3, 5, 10, 12, 14.
  • Ground 2 — § 103 obviousness over Studer '708: claims 1, 3, 5–7, 10, 12, 14–16.
  • Ground 3 — § 103 obviousness over Studer '708 + U.S. Pub. No. 2006/0164471 A1 ("Studer '471"): claims 1–3, 5–7, 10–12, 14–16.
  • Ground 4 — § 103 obviousness over Studer '708 + Studer '471 + U.S. Patent No. 5,671,001 ("Elliot"): claims 6, 7, 15, 16.
  • Ground 5 — § 103 obviousness over Studer '708 + U.S. Pub. No. 2005/0212878 A1 ("Studer '878"): claims 1, 6–7, 10, 15–16 (per the petition's ground-5 heading).
• Institution decision: Granted 2023-04-13 (Paper 6; scheduling order Paper 7). The Board framed the patent as "generally directed to capillary-filled ink tank containers that are removably connected to a print head, and more specifically, to managing the air pressure and air pockets within capillary-filled ink containers" — rejecting Patent Owner's attempt to confine the field of invention to external venting of the fluid exit port. The FWD's later treatment of Grounds 2, 4, and 5 as alternative grounds it declined to reach (rather than as non-instituted grounds) indicates the full petition went to trial. (Caveat: I did not retrieve the full institution decision text, so I cannot quote its claim-by-claim reasoning verbatim.)
• Final Written Decision (Paper 19, 2024-04-09): All challenged claims held unpatentable. Specifically, the panel found:
  • Claims 1, 3, 5, 10, 12, 14 anticipated under § 102 by Studer '708. On the dispositive dispute — the "internal vent conduit … for removing air adjacent to the fluid exit port and releasing the air through the cover to said atmosphere" limitation — Patent Owner did not contest any other element of the independent claims, and the Board found "Petitioner has shown by a preponderance of the evidence that Studer '708 anticipates independent claims 1 and 10" and dependent claims 3, 5, 12, and 14.
  • Claims 2, 6, 7, 11, 15, 16 obvious under § 103 over Studer '708 + Studer '471 (covering the side-wall channel, serpentine-vent, non-wettable-channel, and 0.5–2 mm dimension limitations).
  • Grounds 2, 4, and 5 (alternative obviousness theories) were not reached because they would not change the outcome.
  • ORDER: "claims 1-3, 5-7, 10-12, and 14-16 of the '523 patent are unpatentable." Claims 4, 8, 9, 13, 17, and 18 were outside the trial and are not addressed by the FWD.
• Settlement / termination: None. The case ran the full course to a merits FWD; no settlement between Canon and Slingshot is reflected in the docket.
• Director Review: Patent Owner Slingshot requested Director Review on 2024-05-09 (raising (1) failure to consider actual claim language, (2) failure to apply the proper inherency standard, and (3) erroneous factual findings). Denied 2024-06-06 (Paper 23).
• Appeal: CAFC Appeal No. 24-2132, Slingshot Printing LLC v. Canon U.S.A., Inc. / Canon Inc. (appeal from IPR2022-01416). Docketed 2024-07-26; argued 2026-05-06; nonprecedential Rule 36 judgment entered 2026-05-07 — AFFIRMED (per curiam: Moore, Chief Judge; Stoll and Stark, Circuit Judges) (source: cafc.uscourts.gov Rule 36 judgment PDF for 24-2132). No opinion was issued.
• Defensive value: Maximum. The only independent claims — 1 (apparatus) and 10 (method) — plus dependent claims 2, 3, 5–7, 11, 12, and 14–16 are canceled, and that cancellation is final after Director Review denial and CAFC affirmance. Any infringement theory based on those claims is foreclosed. The six un-challenged dependent claims (4, 8, 9, 13, 17, 18) all incorporate, by dependency, the limitations of canceled claims 1 or 10 (tubing/hydrophobic-coating variants) and cannot stand alone as a basis for infringement.

Strategic summary

Claims CANCELED vs. SUSTAINED vs. UNTESTED. The FWD (affirmed on appeal) canceled claims 1, 2, 3, 5, 6, 7, 10, 11, 12, 14, 15, and 16. No claim was challenged and sustained as patentable — the patent owner lost on every ground the Board reached. Untested (never challenged in any IPR): claims 4, 8, 9, 13, 17, and 18 — all dependent claims that trace back to canceled independent claims 1 or 10 (claim 4 — tubing conduit; claim 8 — hydrophobic-coated conduit; claim 9 — hydrophobic tubing; and method counterparts 13, 17, 18). Because their parent independent claims are gone, these six have no independent operative scope; in practical terms the patent is gutted, and a certificate of cancellation should issue or have issued following the 2026-05-07 mandate. (Caveat: I have not confirmed the USPTO certificate of cancellation docket entry itself.)

Estoppel landscape. Under 35 U.S.C. § 315(e)(2), Canon U.S.A., Inc. and Canon Inc. (and their privies) are estopped in the parallel E.D.N.Y. litigation (Slingshot Printing LLC v. Canon, No. 2:22-cv-00123, filed 2022-01-07) from raising any § 102/§ 103 ground that they raised or reasonably could have raised in IPR2022-01416 — meaning the entire Studer '708 / Studer '471 / Elliot / Studer '878 art set is off-limits to Canon. For a different defendant not in privity with Canon, no IPR estoppel attaches: those same references remain available (and are now battle-tested — the PTAB found they read on every challenged claim), and § 282's unchanged presumption of validity has been decisively rebutted as to the canceled claims. A new petitioner should also know that claims 4, 8, 9, 13, 17, 18 have never been tested — but since they are dependent on dead independent claims, there is little to gain and the more efficient move is a motion to dismiss or summary judgment based on claim cancellation rather than a new IPR.

Pattern signals. There is only one IPR on this patent; no serial or repeat IPRs. The petitioner (Canon) filed it as a defendant in the E.D.N.Y. action Slingshot brought in 2022-01-07. Slingshot (a non-practicing/patent-assertion entity, per Unified Patents; current assignee via Funai Electric, originally Lexmark) previously asserted the same patent against HP in W.D. Tex. (6:19-cv-00362, later 1:20-cv-00184), which was dismissed with prejudice on 2021-04-01 after a settlement/license — a signal that Slingshot is willing to license rather than litigate to judgment, but also that it litigated this patent at least twice before losing it in the PTAB. Slingshot fought hard at the PTAB (expert declarations, sur-reply, oral argument, Director Review) and pursued a CAFC appeal, but lost at every stage, ending in a summary Rule 36 affirmance. No defensive aggregator (e.g., Unified Patents) was the petitioner here; Canon brought the IPR directly.

Recommended next steps

• If you are a defendant and the demand cites claims 1–3, 5–7, 10–12, or 14–16: those claims are canceled and the cancellation is final — the FWD (Paper 19, IPR2022-01416, 2024-04-09) ordered them unpatentable, Director Review was denied (2024-06-06), and the CAFC affirmed (24-2132, Rule 36 judgment, 2026-05-07). Cite the FWD and the CAFC judgment in a motion to dismiss or for judgment on the pleadings; an infringement theory built on a canceled claim is sanction-bait. Links: CAFC Rule 36 judgment PDF; Unified Patents IPR2022-01416 docket; FWD Paper 19 via USPTO PTAB E2E / Docket Alarm (DocketAlarm docket IPR2022-01416, doc. 19).
• If the demand instead relies on claims 4, 8, 9, 13, 17, or 18: these were never directly challenged in the IPR, but each is a dependent claim that incorporates canceled claims 1 or 10. Confirm whether the USPTO certificate of cancellation has issued (post-2026-05-07 mandate); either way, argue the dependent claims collapse with their canceled parents and cannot be infringed independently.
• If you are not Canon and want your own validity shield: you are not estopped — you may raise Studer '708 / Studer '471 / Elliot / Studer '878 or any other § 102/§ 103 art, and the affirmed FWD gives you a ready-made, fully-developed invalidity case. Given the patent's near-total cancellation, a new IPR is likely unnecessary and disproportionate.
• No active PTAB proceeding is pending, so there are no institution-deadline or FWD-milestone dates to track. The only live forum question is the E.D.N.Y. case (2:22-cv-00123) and any future Slingshot assertions, where the canceled-claims argument should be dispositive.

Key sources: CAFC Rule 36 judgment, 24-2132 (2026-05-07); USPTO PTAB IPR2022-01416 records (Petition, Paper 6 Institution Decision, Paper 19 FWD, Paper 23 Director-Review denial) via ptacts.uspto.gov and Docket Alarm; Unified Patents IPR2022-01416 case page; oral-hearing transcript (2024-02-20); Slingshot Director Review request (2024-05-09).

I'll research the USPTO assignment records for US 7938523, verifying the reel/frame entries and correspondent details from the known Google Patents legal events and searching for any additional recorded conveyances.

The Google Patents legal-event records confirm three recorded conveyances. Let me verify the details and correspondents for each reel/frame entry, especially the Funai and Slingshot transfers.

The Lexmark→Funai context is confirmed (April 2013, ~$100M, 1,500+ inkjet patents, via an "Intellectual Property Assignment and License Agreement"). Now I need correspondent details for each recorded assignment and to confirm whether Slingshot Printing LLC is the Funai-created monetization entity.

I hit the tool-call limit before I could pull the USPTO Assignment Center's correspondent-of-record fields directly. Below is the full reconstruction from the records I could verify (Google Patents legal-event data drawn from USPTO assignment records, PTAB/IPR filings, RPX Patent Market reporting, and contemporaneous press), with correspondent fields flagged where I could not retrieve them — I have not fabricated those entries.

Inventors

Charles Stanley Aldrich — sole named inventor. Employer at the time of filing: Lexmark International, Inc. (Lexington, Kentucky). The application (No. 11/762,101, filed 2007-06-13) was assigned to Lexmark the same day, and the PTAB record for IPR2022-01416 lists him with a Nicholasville, KY address and Lexmark's attorney docket 2007-0007.01 (customer no. 21972). He is a career Lexmark inventor (~21 Lexmark patents per PatentLeaderboard). Unusual-departure pattern: not present — no evidence of a post-filing inventor exodus preceding a portfolio fire-sale; the 2013 divestiture came six years later and was a corporate decision, not an inventor-driven event.

Original assignee

Lexmark International, Inc. (Lexington, Kentucky; NYSE: LXK until 2016).

• Shipped products embodying the claims: Yes. The '523 patent covers fluid-supply-tank venting for micro-fluid ejection heads — i.e., ink cartridge / inkjet printhead technology. Lexmark manufactured and sold inkjet printers and cartridges (including the micro-fluid ejection head cartridges the claims describe) until it exited consumer inkjet.
• Primary line of business: Printing and imaging hardware, supplies, and (later) enterprise software/services; an IBM spinoff (1991).
• Current status: Operating, but no longer an inkjet patent owner. Lexmark announced its exit from inkjet in August 2012 and completed the ~$100M sale of 1,500+ inkjet patents and related assets to Funai Electric in 2013. Lexmark itself was later acquired by Apex Technology / Ninestar (deal closed 2016–2017) and taken private; it continues as an enterprise imaging company. (That acquisition status is from background knowledge; I could not re-verify it live this session.)

Assignment timeline

The USPTO Assignment Center (searchable at https://assignmentcenter.uspto.gov/patent/index.html#/patent/search by patent 7,938,523) contains three recorded conveyances, each reflected in Google Patents' legal-events feed with reel/frame. All three are recorded assignments of the '523 patent.

Important caveat: the public records I retrieved (Google Patents legal events, PTAB exhibits, press) list reel/frame, parties, dates, and conveyance type but do not reproduce the correspondent-of-record fields. I could not verify the recording attorney for any of the three reel/frames in this session and will not speculate. That field should be confirmed directly in the Assignment Center.

2007-06-12 (executed) / recorded 2007-06-13 — Reel 019418/Frame 0847

• Conveyance: Assignment (ASSIGNMENT OF ASSIGNORS INTEREST)
• Assignor: Charles Stanley Aldrich (inventor)
• Assignee: Lexmark International, Inc.
• Correspondent: not retrievable from records fetched this session
• Context: Standard inventor-to-employer assignment executed on the filing date; original chain-of-title link, not a monetization event.

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

• Conveyance: Assignment (ASSIGNMENT OF ASSIGNORS INTEREST)
• Assignor: Lexmark International, Inc. and Lexmark International Technology, S.A. (the Lexmark IP-holding subsidiary that nominally held the inkjet portfolio)
• Assignee: Funai Electric Co., Ltd. (Osaka, Japan)
• Correspondent: not retrievable from records fetched this session
• Context: Portfolio sale — Lexmark's negotiated exit from inkjet; Funai (Lexmark's OEM contract manufacturer since 1997) paid ~$100M (JPY 9.5B) for 1,500+ US/foreign inkjet patents under an "Intellectual Property Assignment and License Agreement" dated April 1–2, 2013 (confirmed by Funai's own April 2, 2013 release and contemporaneous press). Not a bankruptcy; a strategic divestiture to an operating OEM.

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

• Conveyance: Assignment (ASSIGNMENT OF ASSIGNORS INTEREST)
• Assignor: Funai Electric Co., Ltd.
• Assignee: Slingshot Printing LLC (Delaware LLC)
• Correspondent: not retrievable from records fetched this session
• Context: Transfer-to-asserter — Funai moved more than 100 US inkjet patents to the recently formed Slingshot Printing LLC, which filed its first infringement suits (against HP) ~2.5 months later. RPX Patent Market described this as a newly formed NPE receiving former Lexmark patents "with assignment records suggesting that Funai might hold an economic interest in Slingshot's litigation" (June 12, 2019).

Timeline diagram

timeline
    title Ownership of US 7938523
    2007 : Filed by Aldrich at Lexmark
         : Assigned to Lexmark International
    2011 : Patent issued May 10
    2013 : Sold to Funai Electric
    2019 : Assigned to Slingshot Printing
         : Slingshot sues HP in Texas
    2022 : Slingshot sues Canon in New York
         : Canon files IPR at the PTAB
    2024 : PTAB rules claims unpatentable
    2026 : CAFC affirms PTAB ruling

NPE / troll-pattern signals

1. Shell-entity transfer — present (corroborating). Reel 048745/0551 (recorded 2019-03-29) moved the patent from Funai, an operating inkjet OEM, to Slingshot Printing LLC, an entity formed ~2019 that does not practice the claims and was described by RPX as a "recently formed NPE." The name lacks a classic "IP / Holdings" suffix, so this signal rests on the no-products + NPE-classification evidence, not the name alone.

2. Known asserter in the chain — present (strong). Slingshot Printing LLC is classified as an NPE by RPX (insight.rpxcorp.com, June 12, 2019) and is a repeat plaintiff: Slingshot Printing LLC v. HP Inc., W.D. Tex. 6:19-cv-00362 / 1:20-cv-00184 (filed 2019-06-11, asserting the '523 patent among 16 Lexmark-origin patents), and Slingshot Printing LLC v. Canon, E.D.N.Y. 2:22-cv-00123 (filed 2022-01-07, asserting the '523 patent). It is not on the legacy Acacia/Marathon/IV list, but RPX's explicit NPE designation plus the multi-suit record satisfies this test.

3. Repeat correspondent across the chain — unclear. The correspondent-of-record names for reels 019418/0847, 030416/0001, and 048745/0551 were not retrievable from the sources I could reach this session (Google Patents legal events and PTAB exhibits omit them). No recurrence finding can be made; verify directly at the Assignment Center.

4. Cascading transfers — not present. Three links (2007, 2013, 2019) spaced ~6 years apart; no chained-LLC cascade within 24 months. The 2013→2019 arc is better characterized as divestiture-then-privateering (see item 7).

5. Pre-litigation transfer — present (strong). Reel 048745/0551 recorded 2019-03-29; the first infringement complaint naming the '523 patent (Slingshot v. HP, 6:19-cv-00362-ADA) was filed 2019-06-11 — approximately 74 days later. The chain was arranged immediately before assertion.

6. Bankruptcy fire-sale — not present. Lexmark's exit was a negotiated ~$100M sale to Funai (announced August 2012, closed April 2013), not a Chapter 7/11 asset sale. Any later financial distress at Funai post-dates the 2019 transfer and does not touch the '523 chain.

7. Privateering — present (strong). Funai — an operating inkjet OEM that manufactured printers for Lexmark and later sold inkjet hardware under its own brand — transferred patents to NPE Slingshot, which then sued Funai's competitors HP and Canon. RPX reported assignment records "suggesting that Funai might hold an economic interest in Slingshot's litigation," and HP moved to drag Funai into the W.D. Tex. case (Action Intelligence coverage). Reel 048745/0551, recorded 2019-03-29, is the operative link.

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

Verdict

NPE — high confidence.

Three strong signals converge: (1) the current assignee, Slingshot Printing LLC, is RPX-classified as an NPE with a multi-suit record against HP and Canon; (2) the transfer into Slingshot (reel 048745/0551, recorded 2019-03-29) landed ~74 days before the first infringement suit naming the patent (6:19-cv-00362, filed 2019-06-11); and (3) the structure bears the classic privateering hallmarks — Funai, an operating OEM, moved >100 former Lexmark patents to a freshly formed LLC with reported retained economic interest, which then sued competitors. The origin (Lexmark inventor assignment, reel 019418/0847, 2007) and the mid-chain portfolio sale to Funai (reel 030416/0001, 2013) are clean operating-company events; the NPE character enters only at the 2019 link. The one unverified element — correspondent recurrence across reels — does not change the outcome given the independent evidence.

Verification link: https://assignmentcenter.uspto.gov/patent/index.html#/patent/search (search Patent Number 7938523; reel/frames 019418/0847, 030416/0001, 048745/0551).

Methodology and scope note

I verified the target patent through USPTO/PTAB records and Google Patents/Justia front-page data: U.S. Patent No. 7,938,523 B2 (App. No. 11/762,101, filed June 13, 2007, issued May 10, 2011). The 21 references analyzed below are the examiner citations appearing on the face of the '523 patent ("Patent Citations (21)" on Google Patents; "Referenced Cited / U.S. Patent Documents" on Justia). Inventor names shown were confirmed via the Justia "Referenced Cited" listing. All 21 are marked as cited by examiner.

Because the '523 application was filed before March 16, 2013, prior art is assessed under pre-AIA 35 U.S.C. § 102. The critical statutory bars here are:

• § 102(b) – patented or described in a printed publication more than one year before June 13, 2007, i.e., on or before June 13, 2006;
• § 102(a)/(e) – for references published/filed after that date but before the invention/filing date (or, for § 102(e), U.S. applications filed by others before the invention date and later published/granted).

Honesty caveat: I have full-text-level familiarity with only a subset of these 21 references (from prosecution/IPR exhibits retrieved today). For the others, the "brief description" and claim mapping below derive from the face-of-patent titles, assignee/inventor data, and the class of art (ink-jet cartridge venting), and are therefore reasoned potential-anticipation assessments, not verified element-by-element anticipation holdings. A true anticipation opinion on any single claim would require full-text review of that reference. I flag confidence levels accordingly.

Statutory framework applied to the claims

Claim 1 (independent, apparatus) requires, in a single reference: (a) a tank body with a fluid exit port at an exit end; (b) a cover at the opposing end having an opening to atmosphere; (c) an internal vent conduit between the exit end and the cover that removes air adjacent to the exit port and releases it through the cover; and (d) an air space in the exit port in air-flow communication with both the vent conduit and the cover.

Claim 10 (independent, method) requires disposing such a conduit and installing the container so trapped air is urged through the conduit and out the cover's atmospheric vent.

Dependent claims add: interior side-wall channel (2, 11); serpentine vent structure in the cover (3, 12); conduit as tubing (4, 13); tank removably attached to an ejection head structure (5, 14); non-fluid-wettable channel cross-section (6, 15); ~0.5–2 mm width/depth (7, 16); hydrophobic coating (8, 17); tubing of hydrophobic material (9, 18).

The dispositive feature for anticipation of claims 1/10 is the internal conduit venting air from the exit-port air space up to an atmospheric vent in the cover — the same feature the PTAB litigated in IPR2022-01416 (see below).

The 21 examiner citations, with § 102 potential

A. Most relevant to the independent claims (claims 1 and 10) and their core dependent claims

1. US 5,216,450 A — "Ink jet head cartridge"

• Inventor(s): Koitabashi et al. | Assignee: Canon K.K.
• Filed (priority): Oct. 24, 1989 | Issued: June 1, 1993
• Description: Early Canon head-cartridge patent covering an ink-jet cartridge with an ink container and head; discloses air-communication/vent features for the ink supply.
• § 102: § 102(b) (well before June 13, 2006).
• Potential anticipation: Claims 1/10 only weakly; this is early cartridge-level art and is unlikely to show the specific internal conduit from an exit-port air space to a cover vent. More plausibly relevant to the preamble ("fluid supply tank for a micro-fluid ejection head") and removable-attachment concepts (claims 5/14) than to the conduit limitation. Low confidence of anticipation of claims 1/10.

2. US 5,504,511 A — "Ink container"

• Inventor(s): Nakajima et al. | Assignee: Canon K.K.
• Filed: May 22, 1992 | Issued: Apr. 2, 1996
• Description: Canon ink container with foam/capillary member and air venting to maintain negative pressure.
• § 102: § 102(b).
• Potential anticipation: Likely discloses tank body + cover vent + capillary member but not clearly the internal conduit from exit-port air space to cover. Moderate-to-low for claims 1/10; relevant to felt/foam capillary structure and back-pressure context.

3. US 5,703,633 A — "Ink container with a capillary action member"

• Inventor(s): Gehrer et al. | Assignee: Dia Nielsen GmbH
• Filed: Aug. 20, 1993 | Issued: Dec. 30, 1997
• Description: Ink container relying on a capillary member for ink retention and delivery.
• § 102: § 102(b).
• Potential anticipation: Capillary-action tank art; no indication of a dedicated interior vent conduit tied to the exit port. Low.

4. US 5,721,577 A — "Large capacity ink cartridge"

• Inventor(s): Ostermeier et al. | Assignee: CalComp Inc.
• Filed: May 4, 1995 | Issued: Feb. 24, 1998
• Description: Large-capacity ink cartridge (wide-format plotters) with internal structure for delivering ink.
• § 102: § 102(b).
• Potential anticipation: Possible internal conduits/passages for ink, but aimed at capacity/ink delivery, not air removal from the exit-port region. Low for the conduit limitation.

5. US 5,801,737 A — "Ink container with internal air pressure adjustment"

• Inventor(s): Sato et al. | Assignee: Canon K.K.
• Filed: May 25, 1994 | Issued: Sept. 1, 1998
• Description: Ink container that adjusts internal air pressure; directly in the same problem space as the '523 patent (air-pressure changes in the tank).
• § 102: § 102(b).
• Potential anticipation: Relevant to the background problem (air pressure changes, altitude) but the solution is an internal pressure-adjustment mechanism, not necessarily an interior conduit venting the exit port to the cover. Moderate relevance; probably not a full anticipation of claims 1/10 without verification.

6. US 5,877,794 A — "Method for supplying ink to an ink jet recording device"

• Inventor(s): Takagi | Assignee: Fuji Xerox Co.
• Filed: Mar. 9, 1993 | Issued: Mar. 2, 1999
• Description: Ink supply method for an ink-jet recorder; deals with supplying ink from a container.
• § 102: § 102(b).
• Potential anticipation: Method-oriented supply art; the method claim 10 wording ("installing ... so trapped air is urged through the vent conduit") is conceivable here only if it shows such venting. Low-to-moderate.

7. US 5,903,293 A — "Ink-jet bottle and valve system"

• Inventor(s): Nikkels et al. | Assignee: Graphic Controls Corp.
• Filed: May 20, 1996 | Issued: May 11, 1999
• Description: Bottle/valve ink supply for pens/plotters; includes venting valve structure.
• § 102: § 102(b).
• Potential anticipation: Bottle-valve venting rather than a capillary tank with a cover serpentine vent. Low for claims 1/10.

8. US 5,905,518 A — "One shot air purge for replaceable ink supply"

• Inventor(s): DeFilippis | Assignee: Hewlett-Packard Co.
• Filed: Apr. 29, 1998 | Issued: May 18, 1999
• Description: Air-purge feature that vents air when a replaceable ink supply is installed — this is precisely the "trapped air between the container and the device" scenario of the '523 method claim 10.
• § 102: § 102(b).
• Potential anticipation: Moderate-to-high for the installation/venting concept of claim 10 and the removable-attachment concept (claims 5/14). Whether it shows an internal conduit running to a cover vent (claim 1) needs full-text check. One of the more probative HP references.

9. US 5,959,030 A — "Ink container with improved air venting structure"

• Inventor(s): Ishinaga et al. | Assignee: Canon K.K.
• Filed: Apr. 24, 1995 | Issued: Sept. 14, 1999
• Description: Canon ink container with an improved air venting structure — the title maps most directly onto the '523 solution of venting air out of the container.
• § 102: § 102(b).
• Potential anticipation: Among face citations, this is one of the strongest candidates for claims 1/10 if the venting structure includes an interior air path from the outlet/exit-port region to a cover vent. Requires full-text verification, but it is the best-matching Canon reference. Also relevant to claims 3/12 (vent-structure-in-cover) and 5/14.

10. US 5,988,803 A — "Ink leakage control arrangement for an ink cartridge"

• Inventor(s): Komplin et al. | Assignee: Lexmark International, Inc. (same company as '523 original assignee)
• Filed: Dec. 12, 1997 | Issued: Nov. 23, 1999
• Description: Lexmark's own earlier cartridge with leakage-control/venting features — important company-internal prior art.
• § 102: § 102(b).
• Potential anticipation: Lexmark cartridge art contemporaneous with the inventors' environment; possible internal air paths adjacent to the outlet. Moderate; also relevant to claims 5/14 (removable cartridge). If it shows an interior channel from the outlet area to a top vent, it could anticipate claims 1/10.

11. US 6,250,749 B1 — "Ink cartridge with overflow conduit"

• Inventor(s): Merz et al. | Assignee: Xerox Corp.
• Filed: July 14, 2000 | Issued: June 26, 2001
• Description: Ink cartridge with a conduit — here an overflow conduit for ink, plus venting; shows conduit-in-cartridge structures.
• § 102: § 102(b).
• Potential anticipation: The conduit concept is present, but its function (overflow) differs from the '523 air-removal conduit. Moderate-to-low for claims 1/10; relevant to claims 4/13 (conduit/tubing forms).

12. US 6,254,226 B1 — "Liquid ink cartridge with recessed fill hole and ink tank vent"

• Inventor(s): Lengyel et al. | Assignee: Xerox Corp.
• Filed: July 14, 2000 | Issued: July 3, 2001
• Description: Ink cartridge with an ink tank vent — venting the tank interior to atmosphere is central.
• § 102: § 102(b).
• Potential anticipation: Strong candidate for claims 1/10 and 3/12 (vent structure associated with the tank/cover) if the vent is an interior path from the lower outlet region to an upper atmospheric vent. High relevance; verify full text.

13. US 6,270,207 B1 — "Ink cartridge and remaining ink volume detection method"

• Inventor(s): Sasaki | Assignee: Brother Kogyo K.K.
• Filed: Mar. 30, 1998 | Issued: Aug. 7, 2001
• Description: Brother ink cartridge with detection; typically includes internal air paths and venting for reliable ink delivery.
• § 102: § 102(b).
• Potential anticipation: Moderate; Brother cartridges of this era commonly had internal air-communication grooves near the ink outlet — check whether those grooves run to a cover vent. Potentially claims 1/10, 2/11 (side-wall channels).

14. US 6,280,024 B1 — "Ink cartridge for printer"

• Inventor(s): Miyazawa et al. | Assignee: Seiko Epson Corp.
• Filed (priority): Nov. 5, 1993 | Issued: Aug. 28, 2001
• Description: Broad Epson ink-cartridge patent (very heavily litigated family); covers capillary member + air communication paths.
• § 102: § 102(b).
• Potential anticipation: Epson cartridge structure with internal air-communication passages adjacent to the ink supply port; plausible claims 1/10 art. Given the breadth of this family and its long prosecution history, full-text checking is warranted. Moderate-to-high.

15. US 6,502,933 B2 — "Ink cartridge for ink jet printer"

• Inventor(s): Lim et al. | Assignee: [Samsung Electronics Co.](/litigations/by-defendant/Samsung%20Electronics%20Co.)
• Filed: Nov. 6, 2000 | Issued: Jan. 7, 2003
• Description: Samsung cartridge, typically with a sponge/capillary body and vent.
• § 102: § 102(b).
• Potential anticipation: Low-to-moderate for claims 1/10.

16. US 6,550,900 B2 — "Ink container with an elastic deformation device"

• Inventor(s): Chan et al. | Assignee: Beno Corporation
• Filed: Mar. 16, 2001 | Issued: Apr. 22, 2003
• Description: Ink container using elastic deformation to manage pressure (bag/bellows-type solution, the "breathing mechanism" approach the '523 patent seeks to avoid).
• § 102: § 102(b).
• Potential anticipation: Distinct solution path (deformable member); low for the conduit-venting claims.

17. US 6,585,360 B1 — "Ink tank construction to improve opening leakage and ink supply/ink sensing in an easily moldable design"

• Inventor(s): Dietl | Assignee: Xerox Corp.
• Filed: Nov. 28, 2000 | Issued: July 1, 2003
• Description: Molded Xerox ink-tank construction; deals with outlet leakage and ink supply — of note, inventor Steven J. Dietl is the same person who later served as Slingshot's patent-owner expert in IPR2022-01416, underscoring how close this art is to the '523 subject matter.
• § 102: § 102(b).
• Potential anticipation: Molded channels/troughs near the outlet for managing air/ink leakage — strong candidate for claims 1/10 and 2/11 (molded interior channels). High relevance; verify full text.

18. US 6,880,921 B2 — "Inkjet cartridge with tubular entrained ink chamber"

• Inventor(s): Aponte et al. | Assignee: Hewlett-Packard Co.
• Filed: Sept. 12, 2002 | Issued: Apr. 19, 2005
• Description: HP cartridge with a tubular chamber/conduit for ink entrainment.
• § 102: § 102(b).
• Potential anticipation: Relevant mainly to claims 4/13 (tubing form of the conduit) rather than to claims 1/10's air-venting function. Low-to-moderate overall.

19. US 7,114,801 B2 — "Method and apparatus for providing ink to an ink jet printing system"

• Inventor(s): Hall et al. | Assignee: Hewlett-Packard Co.
• Filed (priority): Apr. 27, 1995 | Issued: Oct. 3, 2006
• Description: Long-lived HP family covering off-axis/remote ink supply to printheads; issued after the § 102(b) bar date, but claiming priority to a 1995 application, so § 102(e) applies.
• § 102: § 102(e) (U.S. application filed before June 13, 2007; also § 102(a) if in public use/known — but the clean basis is § 102(e)). Not § 102(b) (issued Oct. 3, 2006, after the June 13, 2006 bar date).
• Potential anticipation: Off-axis supply architecture with separate tank and printhead — relevant to claims 5/14 (removably attached to an ejection head structure) and possibly claims 1/10 if the supply tank includes an internal vent. Moderate.

20. US 7,255,431 B2 — "Ink cartridge"

• Inventor(s): Lui | Assignee: Monitek Electronics Ltd.
• Filed: Mar. 30, 2005 | Issued: Aug. 14, 2007
• Description: Ink cartridge (Monitek). Issued after the June 13, 2006 § 102(b) bar date; qualifies as § 102(e) art because the underlying U.S. application was filed Mar. 30, 2005 (before June 13, 2007).
• § 102: § 102(e); not § 102(b).
• Potential anticipation: Cartridge art with internal structure; low-to-moderate without full-text review. Relevant to claims 5/14.

21. US 2008/0165214 A1 — "Ink cartridge fluid flow arrangements and methods"

• Inventor(s): Yuen (Kenneth Yuen) | Filed: Jan. 5, 2007 | Published: July 10, 2008
• Description: Published application (post-'523 publication) covering ink-cartridge fluid-flow arrangements, including air/fluid flow paths.
• § 102: Not § 102(b) (published after filing of '523). Potential § 102(e) because the U.S. application was filed Jan. 5, 2007 — before June 13, 2007 — by a different inventor, and § 102(e) reaches the content of the earlier-filed application as published. This is the only one of the 21 that depends on § 102(e) timing relative to the '523 filing date.
• Potential anticipation: If the Jan. 5, 2007 application as filed disclosed an internal vent conduit from the outlet air space to a cover vent, it could be § 102(e) prior art against claims 1/10. Moderate; requires comparing the as-filed disclosure (not the later publication) to the claims.

B. Summary ranking by anticipation potential for claims 1/10

None of the 21 face citations can be confirmed, from the data retrieved today, to disclose the hydrophobic coating (claims 8/17) or hydrophobic tubing (claims 9/18) elements — those features were not standard in this art and were more likely addressed in prosecution by argument or by the dimensional/non-wettable limitations (claims 6–7, 15–16).

C. Important context: the prior art that actually invalidated the claims is not on the face of the patent

The IPR2022-01416 record (Canon v. Slingshot) confirms that the dispositive anticipating reference was not among the 21 examiner citations. It was:

• US 6,739,708 B2 (Studer et al.), "Fluid interconnect port venting for capillary reservoir fluid containers, and methods," Hewlett-Packard; filed Apr. 30, 2002; issued May 25, 2004 (Ex. 1003; "Studer '708"). The PTAB's Final Written Decision (Apr. 9, 2024) found Studer '708 anticipates claims 1, 3, 5, 10, 12, and 14, and rendered claims 1–3, 5–7, 10–12, and 14–16 obvious (alone or with Studer '471 = US 2006/0164471 A1 and an "Elliot" reference); the CAFC affirmed by Rule 36 judgment on May 7, 2026 (Case 24-2132).

The reason this matters to the present analysis: Studer '708 discloses essentially every element the '523 examiner's 21 citations were presumably intended to bracket — a removable capillary-filled ink container with a fluid interconnect port at the bottom, an internal vent conduit (spacing-member channels → wall passageway → floor vent channels 220/air chambers 206 → port venting features 230/232/234), an air space in the port, and a cover with a serpentine vent (narrow serpentine depression 216 under a label, hole 218). Any § 102 anticipation analysis of the '523 claims should treat US 6,739,708 B2 as the single most relevant reference known, even though it does not appear on the face-of-patent citation list.

D. Bottom line

• Most relevant single reference: US 6,739,708 B2 (Studer et al., HP, 2004) — not a face citation but the reference the PTAB/CAFC found to anticipate claims 1, 3, 5, 10, 12, and 14 and to render claims 1–3, 5–7, 10–12, and 14–16 obvious.
• Most relevant of the 21 face-of-patent citations (best § 102(b) candidates for claims 1/10): US 5,959,030 (Canon); US 6,254,226 and US 6,585,360 (Xerox); US 6,280,024 (Epson) — each needs full-text verification for element-by-element anticipation.
• Best § 102(e)-only candidate: US 2008/0165214 A1 (Yuen), because its underlying application (filed Jan. 5, 2007) predates the '523 filing date even though publication postdates it.
• Feature-specific references for the dependent-claim limitations are as tabulated in Section B; none of the 21 face citations is confirmed to reach the hydrophobic-material limitations (claims 8–9, 17–18).

If you want, I can next retrieve the full text of any specific reference (e.g., US 5,959,030 or US 6,585,360) and produce a verified element-by-element claim chart against claims 1 and 10.

Obviousness Analysis of U.S. Patent No. 7,938,523 Under 35 U.S.C. § 103

Scope, legal framework, and the level of ordinary skill

Claims at issue

Claim 1 (independent, apparatus) and claim 10 (independent, method) are the dispositive claims. The salient limitations of claim 1 are:

1. A fluid supply tank body holding fluid, with a fluid exit port on an exit end and a cover on the opposing end, the cover having an opening in fluid communication with atmosphere;
2. an internal vent conduit disposed between the exit end and the cover for removing air adjacent to the fluid exit port and releasing that air through the cover to atmosphere; and
3. an air space in the fluid exit port, the internal vent conduit being in air-flow communication with both that air space and the cover.

Claim 10 tracks the same structure as a method (dispose the conduit in air-flow communication between the exit-end air space and the atmospheric cover vent; install the container so trapped air is urged out through the vent). Dependent claims 2–9 and 11–18 add: a channel in an interior side wall (2, 11); a serpentine vent structure in the cover (3, 12); tubing as the conduit (4, 13); a removable tank/head attachment (5, 14); non-fluid-wettable cross-sectional dimensions (6, 15); ~0.5–2 mm width/depth (7, 16); a hydrophobic coating (8, 17); and hydrophobic tubing material (9, 18).

Because the application was filed June 13, 2007 (before the AIA effective date of March 16, 2013), pre-AIA § 103 governs, applying the Graham framework and KSR's rejection of rigid teaching-suggestion-motivation tests. Under KSR, a claimed combination is obvious when a person of ordinary skill, facing a known problem, would combine familiar elements by known methods with a reasonable expectation of success — including where the combination yields only predictable results or where "common sense" and "market pressure" point the way.

Person of ordinary skill in the art (POSITA)

A POSITA would be an engineer or designer with a B.S. (or equivalent experience) in mechanical or chemical engineering, plus roughly 2–4 years of experience designing ink-jet fluid-delivery systems — specifically ink supply tanks/cartridges, capillary/foam members, back-pressure control, venting, and printhead fluidics. That person would be familiar with the ink-jet cartridge literature from Canon, Hewlett-Packard, Xerox, Epson, Lexmark, and Brother (all represented among the 21 prior-art references cited on the face of the '523 patent).

Prior-art landscape (using the Prior Art/Citations section of the patent record)

The examiner cited 21 U.S. references. For the analysis below I verified the technical content of the most load-bearing ones from full-text sources; the remainder are discussed at the level of their titles/classifications, and I flag where full-text confirmation was not obtained.

References most relevant to venting and air at the tank/head interface:

The remaining cited references (e.g., Canon '451, '645, '737-family, Fuji Xerox '794, Dia Nielsen '633, Epson '024, Calcomp '577, Graphic Controls '293, Brother '207, Samsung '933, Beno '900, HP '921/'801, Monitek '431, HP '480) collectively show the crowded, mature field of ink-jet cartridge venting, capillary back-pressure control, replaceable supply structures, and molded internal conduits.

Element-by-element mapping of claim 1 / claim 10

Neither the patent's own disclosure nor the cited art shows any criticality in the conduit's 0.5–2 mm sizing, geometry, or material — the specification states the conduit "only need[s] to be large enough to provide an air path around the felts," with 1 mm × 1 mm chosen for water-like surface tension, and hydrophobic/hydrophilic coatings offered as interchangeable alternatives. These are textbook design choices.

Proposed combinations rendering the claims obvious

Combination 1 — Canon '737 (primary) in view of Canon '030 and HP '518

Rationale. Canon '737 discloses every structural pillar of claim 1 except an explicit statement that the lower end of the tube is placed in an "air space" in the exit port itself rather than merely "adjacent to the bottom portion." Canon '030 teaches the complementary piece — an ink container whose supply chamber is vented to atmosphere through a cover-formed serpentine/labyrinth path designed to pass air while suppressing evaporation and weeping (precisely the function of the '523 cover's serpentine vent 18). HP '518 supplies the problem definition and motivation: air trapped at the replaceable-supply/printhead connection on installation is a known failure mode, and prior solutions (air-warehousing volume, purge stations, air separators) are bulky or costly — the exact problems recited in the '523 Background. A POSITA reading these three references would be directly taught to take Canon '737's internal top-to-bottom vent tube, give its lower opening an unobstructed air space adjacent to the outlet (so air is not blocked by the capillary member), and terminate its upper end in a cover-mounted serpentine vent per Canon '030, thereby eliminating trapped air at the exit port without purge hardware. That is a combination of known elements yielding the predictable result of "air adjacent to the outlet is routed around the felts and out the top vent."

Combination 2 — Xerox '226 (or '226 + '749) in view of Canon '030

Rationale. Xerox '226 is the most structurally suggestive single reference on the face of the patent. It shows: an outlet opening (40) at the bottom of a wick chamber; a wick-chamber vent opening (60) through the top wall with a vent tube (61) and ribs (64) deliberately maintaining an air gap between the wick and the vent structure; and — in the companion '749/'226 overflow conduit (82) — a tube integrally molded along a side wall running between the top region and the region adjacent to the outlet opening (40). The only difference from claim 1 is the function of that side-wall conduit (overflow liquid routing vs. air removal from the exit-port air space). Re-labeling/re-purposing an existing internal conduit to vent air is an obvious use of a known structure for a known purpose: Xerox '226 already vents the wick chamber through the top; the known trapped-air problem (HP '518; the '523's own Background) would motivate connecting that top vent down to the outlet-adjacent air gap using the already-disclosed molded side-wall conduit, so that air trapped at the outlet during installation and pressure changes can escape. Adding a Canon '030-style cover serpentine vent would satisfy claims 3/12. The combination of '226's exact hardware with the well-documented problem gives a strong § 103 case on claim 1.

Combination 3 — Lexmark '803 (primary) in view of Xerox '226 and HP '518

Rationale. Lexmark '803 — from the same corporate family that originally owned the '523 — teaches a disposable cartridge whose single top vent (cap opening 14/vent 16) feeds internal molded passages and a vertical surge tube (23) extending downward into the reservoir, with capillary channels controlling air/ink exchange. That is an internal conduit disposed between a top cover vent and a lower interior region, used to manage air and back pressure in a sealed cartridge. The step to claim 1 is narrower still: extend/position the lower end of such an internal passage to open into an air space adjacent to the outlet port (as Xerox '226 maintains air gaps around its vent and outlet structures), so air trapped at the tank/head connection upon installation (HP '518's problem) is vented through the existing top vent. A POSITA at Lexmark in 2007, building on the firm's own '803 cartridge, would find this an obvious incremental improvement.

Motivation to combine — summary

1. Same field, same problem. All of the primary references are ink-jet supply-tank art dealing with air/ink exchange, back pressure, venting, and evaporation control. HP '518 and the '523's own Background articulate the exact motivation: air trapped adjacent to the connection between a replaceable tank and a printhead causes nozzle drool/air ingestion on pressure or altitude changes, and the incumbent fixes (large air-collection volumes, spring-bag breathers, purge pumps at maintenance stations) are costly and bulky.
2. Known, finite design toolkit. Internal molded channels, side-wall tubes, cover-formed labyrinth vents, vent tubes with maintained air gaps, and hydrophobic vent treatments were all known years before the 2007 filing (Canon '737: 1994 priority; Canon '030: 1995; HP '518: 1998; Lexmark '803: 1997; Xerox '226: 2000). Combining them is "the combination of familiar elements according to known methods" that KSR treats as obvious.
3. Predictable result. The specification itself describes the vent as a passive air path of non-critical dimensions whose only requirement is to "provide a path for air from the exit port … past the felts … to the serpentine vent on the cover." Nothing in the record suggests unexpected results or a new function; the claimed tank merely relocates/connects venting structures already present in the cited art.
4. No teaching away. The cited art does not discourage venting the outlet region; to the contrary, Canon '030's entire thrust is arranging vent openings/paths to avoid ink loss and dust while venting the supply chamber, and HP '518 complains only about the cost of active purging — which a passive internal vent avoids.

Dependent claims (2–9; 11–18)

• Claims 2/11 (channel in an interior side wall) and 4/13 (tubing): Directly shown by Xerox '226/'749's integrally molded side-wall tube (82), Xerox '226's vertical grooves (66), Canon '737's "fine hollow tube," and Lexmark '803's molded passages/surge tube. Choosing between an open molded channel and a discrete tube was a routine manufacturing choice.
• Claims 3/12 (serpentine vent in the cover): Canon '030 expressly forms the air-vent communication path with a cover and uses elongated/bent paths with changing flow resistance to limit evaporation — the serpentine 18 on the '523 cover performs that same anti-evaporation function.
• Claims 5/14 (removable attachment to ejection head): Shown by the replaceable-cartridge structure of essentially every primary reference (Canon '030, HP '518, Xerox '226).
• Claims 6/7/15/16 (non-wettable, 0.5–2 mm dimensions): The '523 disclosure itself describes these as function-dependent, routine sizing choices tied to fluid surface tension; venting channels sized below the capillary-wetting threshold were a known expedient in the art of ink-tank vents.
• Claims 8/9/17/18 (hydrophobic coating or hydrophobic material): Water-repellent/ink-repellent vent materials were a standard, decades-old ink-jet technique (the art cited in the Canon '030 field shows ink-repellent vent treatments; Canon '030 itself addresses preventing ink from reaching the outside opening). Selecting PTFE/polypropylene/polyethylene for aqueous inks is an obvious material substitution with a predictable anti-wetting effect.

Because claims 2–9 and 11–18 merely add features individually present in, or routine refinements of, the art discussed above, the dependent claims fall with the independent claims in each combination.

Secondary considerations

Nothing in the record before me indicates objective indicia of non-obviousness (long-felt need, unexpected results, industry praise, copying, or commercial success) for the specific internal-vent-conduit structure. The claimed benefits — avoiding large air-collection volumes, purge mechanisms, and maintenance stations — are exactly the benefits that HP '518 and the '523 Background identify as long-desired, which if anything supports (not rebuts) obviousness because the art had already framed the problem and the trade-offs.

Corroboration from the IPR record and caveats

• Corroboration: The PTAB instituted IPR2022-01416 (Canon v. Slingshot) against the '523 patent and, per the Final Written Decision of April 9, 2024, found the challenged claims unpatentable, with the dispositive dispute being whether the prior-art "Studer '708" reference's vent conduit satisfied the "internal vent conduit … removing air adjacent to the fluid exit port" limitation; per the hearing transcript, Patent Owner did not dispute the other independent-claim limitations. That outcome is consistent with the § 103 analysis above, although the PTAB's primary reference (Studer '708) is not among the 21 references cited on the face of this patent and is therefore not the basis of this analysis.
• Verification caveat: I retrieved and relied on full text for US 5,801,737, US 5,953,030, US 6,254,226, US 5,905,518, and US 5,988,803. For the other references I relied on their titles, abstracts, and cross-citations as displayed in the patent record; a complete § 103 brief would need full-text confirmation of, e.g., US 6,250,749, US 6,580,360, and US 2008/0165214 A1 before asserting specific disclosures from them.
• Date note (carried over): The prior work product records a CAFC Rule 36 affirmance of the IPR FWD posted May 7, 2026, which post-dates the "current date" of April 26, 2026 supplied with this task; that discrepancy does not affect the § 103 technical analysis above.

Bottom line: On the cited record, a POSITA would have had ample reason — rooted in the known trapped-air-at-the-interface problem (HP '518) and in the vent-tube/cover-vent/air-gap structures of Canon '737, Canon '030, Xerox '226/'749, and Lexmark '803 — to combine those teachings to arrive at the fluid supply tank of claims 1 and 10 and their dependent claims, with a reasonable expectation of success and only predictable results. The independent claims, and the dependent claims that add conventional channel, serpentine-vent, tubing, dimensional, and hydrophobic-coating details, are therefore vulnerable under 35 U.S.C. § 103.