US 7587319

I'll run targeted searches for this exact patent number and its related CAFC/IPR dockets.

Let me check the specific CAFC docket and IPR outcomes.

Let me confirm the scope of the IPR decision and the Rule 36 outcome.

US 7,587,319 B2 — Speech recognition circuit using parallel processors

Sourcing note: The bibliographic data below comes from the authoritative full patent text (Google Patents, fetched 2026-09-29) and corroborating records. Where third-party databases disagree with the patent text, I flag it. Your prompt states the current date as April 26, 2026, but my search results contain later-dated events (a June 8, 2026 CAFC judgment); I report them as found rather than truncating at April.

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1. Bibliographic data

Uncertainty: I do not have the content of the 2010 certificate of correction, so I cannot say whether any claim text in the granted patent differs from the text quoted here. Claim text below is as it appears in the authoritative patent copy.

2. Abstract (as granted)

A speech recognition circuit comprises an input buffer for receiving processed speech parameters. A lexical memory contains lexical data for word recognition. The lexical data comprises a plurality of lexical tree data structures. Each lexical tree data structure comprises a model of words having common prefix components. An initial component of each lexical tree structure is unique. A plurality of lexical tree processors are connected in parallel to the input buffer for processing the speech parameters in parallel to perform parallel lexical tree processing for word recognition by accessing the lexical data in the lexical memory. A results memory is connected to the lexical tree processors for storing processing results from the lexical tree processors and lexical tree identifiers to identify lexical trees to be processed by the lexical tree processors. A controller controls the lexical tree processors to process lexical trees identified in the results memory by performing parallel processing on a plurality of said lexical tree data structures.

3. Plain-language overview of the independent claims

The patent has six independent claims (1, 23, 45, 46, 68, 69) and 63 dependent claims (69 total). Claims 1/23 and 45/46 are two pairs of apparatus claims; 68/69 are their method counterparts.

• Claim 1 (apparatus, means‑plus‑function). A speech‑recognition circuit with five elements: (a) an input for processed speech parameters (e.g., feature vectors); (b) a lexical memory holding many "lexical tree" data structures, each tree modelling a set of words that share prefix components, with a unique initial component per tree; (c) multiple lexical tree processors wired in parallel to the input, each able to search a different tree; (d) a results memory storing both the processors' outputs and lexical‑tree identifiers telling the processors which trees to work on next; and (e) a control processor that directs the parallel processors to the trees identified in the results memory. The core idea is dynamic, controller‑managed work distribution across trees rather than a static split.
• Claim 23 (apparatus, structural counterpart of claim 1). Identical scope to claim 1 but recited with concrete hardware terms instead of "means": an input buffer, a lexical memory, lexical tree processors, a results memory, and a control processor.
• Claim 45 (apparatus, "clustered memory" aspect). Instead of one shared lexicon: several lexical memories that in combination hold the complete lexicon, each holding only a part; processors again in parallel but arranged in groups/clusters, each group tied to one lexical memory; a control processor directs each processor to work using the partial lexical data in its memory; and a receiving element takes back the results. Two extra requirements are folded in: the stored data must be lexical‑tree structures with common‑prefix words and a unique initial component, and the processors must be able to use lexical data for more than one lexical tree at the same time.
• Claim 46 (apparatus, structural counterpart of claim 45). Same clustered‑architecture subject matter, expressed structurally (input buffer, plural lexical memories each holding part of the lexicon, processors in groups each connected to a lexical memory, control processor, results memory). This is the sole independent claim that was challenged in the IPR discussed below.
• Claim 68 (method). The method analogue of claim 1: receive processed speech parameters; store lexical‑tree lexical data (common prefixes, unique initial component); pass the parameters in parallel to multiple lexical tree processors; store results and tree identifiers; and control the processors to work the identified trees in parallel.
• Claim 69 (method). The method analogue of claims 45/46: receive parameters; store the complete lexicon across plural lexical memories, each holding part; process in parallel with processors grouped so each group connects to a lexical memory; control each processor to use partial lexical data from its memory; and store the results.

4. Notable dependent-claim subject matter

Useful context for the family's value: HMM/Viterbi search (claim 22/44/67), mono‑phone trees expanded dynamically into context‑dependent phone models (3/25/49), language‑model scoring at word ends (5/6/27/28/51/52), local and global pruning (13–17, 35, 38–39, 59, 62–63), and cross‑word triphone look‑ahead.

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5. Litigation / PTAB / CAFC status (as found)

PTAB — both petitions won by the challengers:

• IPR2023‑00033, Apple Inc. v. Zentian Ltd., filed 2022‑12‑01/02, instituted 2023‑06‑11/12, final written decision 2024‑06‑11: all challenged claims (46–51, 53, 54, 58, 59, 64, 67) held unpatentable as obvious. Grounds used Thelen (US 6,526,380) + Bailey (US 5,459,798) + Chen (US 5,428,803), with Huang (US 6,076,056) for claims 47–49 and Jiang for 53, 58–59. (case page; Patexia summary)
• IPR2023‑01192, [[Amazon.com Services](/litigations/by-defendant/Amazon.com%20Services) LLC](/litigations/by-plaintiff/Amazon.com%20Services%20LLC) / Amazon Web Services, Inc. v. Zentian Ltd., filed 2023‑07‑12, instituted 2024‑01‑10 and joined to the Apple IPR; FWD 2024‑06‑11, same outcome. The Board declined to require a Sotera stipulation from Amazon and instituted over Zentian's §314(a)/Fintiv arguments. (case page)

CAFC — the appeal was filed (in 2024) and resolved in 2026, not in 2024:

• No. 2024‑2204, Zentian Ltd. v. Apple Inc. (appellees/intervenors also listed as Amazon.com Services LLC and Amazon Web Services, Inc.; appeal from PTAB Nos. IPR2023‑00033 and IPR2023‑01192), docketed 2024‑08‑13.
• Oral argument audio posted June 4, 2026 (CAFC page). The argument concerned, among other things, whether the Board adequately addressed real‑time processing and memory collisions in the Thelen/Bailey/Chen combination.
• Judgment: AFFIRMED under Fed. Cir. R. 36, entered June 8, 2026 — per curiam (Prost, Taranto, Cunningham), nonprecedential, in a one-page Rule 36 order with no reasoned opinion (judgment PDF). A Rule 36 affirmance leaves the PTAB's final written decision as the operative outcome, i.e., claims 46–51, 53, 54, 58, 59, 64, 67 stand as held unpatentable.

Do not conflate this with the September 2026 Zentian decision. A different Zentian v. Apple nonprecedential opinion issued September 25, 2026 affirming an IPR holding all claims of U.S. Patent No. 10,062,377 unpatentable (Fed Circuit Blog; VitaLaw, Sept 28, 2026). That is a related family member, not the '319 patent.

District court matters (from the Google Patents family/litigation block; current 2026 status not verified):

• N.D. Cal. No. 3:23‑cv‑02921
• W.D. Tex. Nos. 6:22‑cv‑00122 and 6:22‑cv‑00123

Expiry. The patent is recorded as Expired – Lifetime, with an adjusted expiration of 2026‑03‑17 — so even aside from the IPR result, the '319 patent's term has run.

6. Explicit caveats

1. Data-quality warning: at least one AI-generated PTAB summary titles US 7,587,319 as "Speech Recognition System Having Parallel Large Vocabulary Recognition Engines." That is the title of the Thelen reference (US 6,526,380), not of the '319 patent. The correct, authoritative title is "Speech recognition circuit using parallel processors," as shown in the patent itself.
2. I have not independently verified the current 2026 docket status of the N.D. Cal. and W.D. Tex. cases, nor whether any petition for rehearing, en banc, or certiorari followed the June 8, 2026 Rule 36 judgment. Rule 36 judgments are nonprecedential and typically end the appeal.
3. I could not retrieve the specific content of the 2010‑09‑21 certificate of correction, so I cannot confirm whether it altered any claim language.
4. The US10/503,463 application number and PCT/GB2003/000459 are reproduced literally as they appear; the unusual 10/503,463 format is a national‑stage renumbering and is not an error on my part.

I'll research the litigation for US patent 7587319 using the sources you specified.

Let me gather more specifics on the district court cases and the Amazon matter.

Let me verify the current status of the remaining district court case and check for any other defendants.

Litigation Involving U.S. Patent No. 7,587,319 ("Speech recognition circuit using parallel processors")

Patent Owner / Plaintiff: Zentian Ltd. (UK). All records below relate specifically to U.S. Patent No. 7,587,319 (the "'319 patent"). Here is the full picture from the patent's litigation records (Google Patents family litigation data) and the underlying court/PTAB documents:

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A. District Court Litigation

1. Zentian Ltd. v. Apple Inc. — W.D. Tex. (later N.D. Cal.)

• Plaintiff: Zentian Ltd.
• Defendant: Apple Inc.
• Jurisdiction/Case No. (original): [U.S. District Court for the Western District of Texas, Waco Division](/courts/western-district-of-texas-waco) — 6:22-cv-00122-ADA (Judge Alan D. Albright)
• Filing date: February 2, 2022
• Asserted patents/claims (as to '319): U.S. Pat. No. 7,587,319, claims 46–51, 53, 54, 58, 59, 64, 67 (asserted alongside the '277, '377, '789, and '140 patents)
• Venue transfer: Judge Albright granted Apple's motion to transfer to the Northern District of California (order issued July 2023; Apple's motion filed Dec. 16, 2022; Apple is headquartered in the NDCA).
• Jurisdiction/Case No. (after transfer): N.D. Cal. — 3:23-cv-02921-TLT (Judge Trina L. Thompson)
• Status: Stayed. On July 26, 2023, the court granted the parties' stipulation to stay the case pending completion of Apple's IPR proceedings. After the June 11, 2024 Final Written Decisions (see below), the parties stipulated (June 25, 2024) to maintain the stay while attempting to settle, with a further case management conference set for Oct. 3, 2024.
• Citations:
  • https://portal.unifiedpatents.com/litigation/California%20Northern%20District%20Court/case/3%3A23-cv-02921
  • Transfer ruling: https://www.winston.com/en/blogs-and-podcasts/wacowatch/judge-albright-grants-defendant-apples-motion-to-transfer-venue-to-the-northern-district-of-california
  • Stay/stipulation: https://storage.courtlistener.com/recap/gov.uscourts.cand.[414047](/patent/414047)/gov.uscourts.cand.414047.125.0.pdf

2. Zentian Ltd. v. Amazon.com, Inc. (Amazon.com Services LLC) — W.D. Tex.

• Plaintiff: Zentian Ltd.
• Defendant: Amazon.com Services LLC / Amazon.com, Inc. (Amazon Lab126 implicated)
• Jurisdiction/Case No.: Western District of Texas, Waco Division — 6:22-cv-00123-ADA (Judge Alan D. Albright)
• Filing date: February 2, 2022 (complaint filed 02/02/22)
• Accused products (context): Echo, Echo Dot, Echo Show, Fire TV devices, Fire tablets, etc.
• Outcome/Status: Terminated November 20, 2024 (case resolved/closed). The '319 patent was one of the patents-in-suit, and Amazon served invalidity contentions relying on Thelen, Bailey, and Jiang.
• Citations:
  • https://portal.unifiedpatents.com/litigation/Texas%20Western%20District%20Court/case/6%3A22-cv-00123
  • Complaint: https://ai-lab.exparte.com/documents/dct/[4379492](/patent/4379492)/6-22-cv-00123_txwd_complaint_exparte.pdf

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B. PTAB — Inter Partes Review (both directly on the '319 patent)

3. Apple Inc. v. Zentian Ltd. — IPR2023-00033

• Petitioner: Apple Inc. Patent Owner: Zentian Ltd.
• Filed: December 2, 2022 (petition date listed as 2022-12-02)
• Institution decision: June 12, 2023 (instituted on all challenged claims/grounds)
• Challenged claims: 46–51, 53, 54, 58, 59, 64, 67
• Grounds: Obviousness over Thelen (U.S. 6,526,380) in view of Bailey (U.S. 5,459,798) and Chen (U.S. 5,428,803); plus Huang (U.S. 6,076,056) and Jiang for dependent claims.
• Final Written Decision: June 11, 2024 — all challenged claims held unpatentable.
• Citation: https://portal.unifiedpatents.com/ptab/case/IPR2023-00033

4. Amazon.com Services LLC & Amazon Web Services, Inc. v. Zentian Ltd. — IPR2023-01192

• Petitioners: Amazon.com Services LLC and Amazon Web Services, Inc. Patent Owner: Zentian Ltd.
• Filed: July 12, 2023 (as a joinder to the Apple IPR)
• Institution + joinder granted: January 10, 2024
• Challenged claims: same set as IPR2023-00033 (46–51, 53, 54, 58, 59, 64, 67)
• Final Written Decision: June 11, 2024 — all challenged claims held unpatentable (identical grounds to the Apple IPR).
• Citation: https://portal.unifiedpatents.com/ptab/case/IPR2023-01192

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C. Federal Circuit Appeal

5. Zentian Ltd. v. Apple Inc. — Fed. Cir. No. 2024-2204

• Appellant: Zentian Ltd. Appellee: Apple Inc.
• Nature: Appeal from PTAB Final Written Decisions in IPR2023-00033 and IPR2023-01192 (both on the '319 patent).
• Outcome: AFFIRMED by per curiam Rule 36 judgment (Prost, Taranto, Cunningham, JJ.).
• Citation:
  • https://portal.unifiedpatents.com/litigation/Court%20of%20Appeals%20for%20the%20Federal%20Circuit/case/24-2204
  • Disposition PDF: https://cases.justia.com/federal/appellate-courts/cafc/24-2204/24-2204-2026-06-08.pdf
  • Docket: https://www.cafc.uscourts.gov/2026/06/08/page/3/

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Summary Table

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Notes, Caveats, and Observations

1. No other defendants found. Searches did not reveal any litigation involving the '319 patent beyond Apple and Amazon. The patent's own litigation record lists exactly these matters (the two Texas cases, the transferred N.D. Cal. case, and the two IPRs/CAFC appeal).

2. '319 patent is part of the same family as the '140 patent (Zentian's U.S. 10,971,140; also 10,217,460 and 10,971,140 lineage), and the district court cases asserted five patents together ('319, '277, '377, '789, '140). Those companion patents were the subject of separate IPRs (Apple: IPR2023-00034, -00035, -00036; Amazon: IPR2023-01193, -01194, -01195, -01197) and additional appeals (e.g., Fed. Cir. 24-2207). I list them only as context; the information above is limited to the '319 patent as requested.

3. Date anomaly — flagging explicitly: You gave today's date as April 26, 2026, but the authoritative search results show the Federal Circuit Rule 36 judgment in No. 24-2204 entered June 8, 2026, and Law360 coverage dated June 8, 2026. I am reporting the outcome as the search results show it (per your instruction to treat search results as ground truth), while noting the chronology cannot be fully reconciled with the stated "current date." If the June 8, 2026 date is not yet reached relative to your working timeline, the appeal should be characterized as pending/argued but undecided, and I would not rely on the affirmance. I could not complete a final live-docket confirmation of the N.D. Cal. case status (search steps were exhausted).

4. Net effect on the '319 patent: Every claim asserted in litigation (46–51, 53, 54, 58, 59, 64, 67) was held unpatentable by the PTAB on June 11, 2024 in IPR2023-00033/-01192, and (per the search results) that holding was affirmed on appeal. The parallel district court action against Apple remains stayed, which is consistent with the IPR outcome.

If you need, I can next pull the individual docket entries (e.g., the N.D. Cal. settlement status reports or the Amazon termination order) from PACER/CourtListener to nail down the exact disposition dates.

I'll flag a contradiction up front: the structured "PTAB proceedings on file" block says no AIA trials, but the authoritative patent text and the prior sections both document two IPRs. Let me verify the claim-level record before resolving that conflict.

Rich detail emerging. Let me pin down the claim-by-claim FWD holdings, the dissent, and confirm no additional '319 petitions exist.

Let me confirm the appeal's finality and check for any later-filed '319 petitions.

⚠️ Sourcing contradiction — flagged up front. The structured "PTAB proceedings on file" block in this prompt states the ODP API returns no AIA trial proceedings for US 7,587,319. That is incorrect. The authoritative patent text delivered in the same prompt (Google Patents "Legal Events" block) contains two literal IPR entries — TRIAL NO: IPR2023-00033 (Opponent: APPLE, INC., effective 2022-12-02) and TRIAL NO: IPR2023-01192 (Opponent: AMAZON.COM SERVICES LLC, AND AMAZON WEB SERVICES, INC., effective 2023-07-12) — and live search confirms both reached Final Written Decisions on 2024-06-11. Per your operating rule to prefer live results over stale/training data, I treat the two IPRs as real and the ODP "no activity" block as a stale/failed-ingest artifact. I do not invent any proceeding number beyond these two.

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Proceedings overview

Two AIA trials exist on US 7,587,319 — both IPRs (no PGR, no CBM), both filed by large operating companies rather than a defensive aggregator; the count is 0 active, 2 with all challenged claims invalidated, 0 sustained as patentable, 0 settled, 0 institution-denied — bottom line: every claim Zentian ever asserted in litigation (46–51, 53, 54, 58, 59, 64, 67) is now held unpatentable and that holding was affirmed, so a demand letter citing any of those claims is worthless, though the untested independent claims 1, 23, 45, 68 and 69 were never challenged and the patent's term had already run (adjusted expiration 2026-03-17) regardless.

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IPR2023-00033 — Apple Inc. v. Zentian Limited

• Type: Inter Partes Review (35 U.S.C. §§ 311–319)
• Filed: 2022-12-02
• Status: Final Written Decision - Appealed — final decision issued 2024-06-11; all challenged claims held unpatentable; PTAB trial terminated; judgment affirmed on appeal.
• Judge panel: Kevin F. Turner, Jeffrey S. Smith, and Christopher L. Ogden, Administrative Patent Judges (Tech Center 2600, Art Unit 2626). Opinion for the Board filed by APJ Ogden; a dissent was filed by APJ Smith — an unusual split at the FWD stage. (Note: a third-party tracker also lists Cathy Underwood against this case number; the FWD caption itself is authoritative and names Turner/Smith/Ogden.)
• Petition grounds (all § 103(a) obviousness; no § 102 or § 112 grounds):
  • Ground 1 — claims 46, 50, 54, 64, 67 obvious over Thelen (US 6,526,380) in view of Bailey (US 5,459,798) and Chen (US 5,428,803).
  • Ground 2 — claims 47, 48, 49 obvious over Thelen + Bailey + Chen + Huang (US 6,076,056).
  • Ground 3 — claims 53, 58, 59 obvious over Thelen + Bailey + Chen + Jiang (US 6,374,219).
  • Ground 4 — claim 51 obvious over Thelen + Bailey + Chen + Katz (US 4,831,550).
  • Claim 46 was the sole challenged independent claim.
• Institution decision: Instituted on all challenged claims and all grounds, Paper 10, dated 2023-06-12 (Apple's Notice of Appeal and the Board's own citations both give 2023-06-12; some trackers list 2023-06-11 — a one-day artifact). The Board declined Zentian's § 314(a)/Fintiv discretionary-denial argument because Apple entered a Sotera stipulation "not [to] pursue in the parallel district court proceeding the same grounds as in the Petition or any grounds that could have reasonably been raised in the pending Petition" (Paper 10 at 7).
• Oral hearing: 2024-03-11 (consolidated hearing with the companion family IPRs).
• Final Written Decision: 2024-06-11 — captioned "Judgment — Final Written Decision Determining All Challenged Claims Unpatentable, 35 U.S.C. § 318(a)." The Board concluded: "Apple has shown by a preponderance of the evidence that claims 46–51, 53, 54, 58, 59, 64, and 67 of the '319 patent are unpatentable under § 103(a)." The order reads: "ORDERED that claims 46–51, 53, 54, 58, 59, 64, and 67 of the '319 patent are unpatentable."
  • Not a single challenged claim survived. The CourtListener stay stipulation (N.D. Cal. 23-cv-02921, ECF 125) tabulates, for IPR2023-00033: Claims Found Unpatentable = "All challenged claims"; Asserted Claims Not Found Unpatentable = "None."
  • Dissent (APJ Smith) reached the opposite conclusion on motivation to combine: "I would have found that Petitioner does not show any reason why a person of ordinary skill in the art would have modified Thelen to include the teachings of Bailey. I also would have found that Petitioner has not shown any reason to modify its combination of Thelen and Bailey to include the teachings of Chen." Smith reasoned that Thelen "already provides the efficiency of sharing data among related sub-context models," "is already scalable and flexible," and that Petitioner failed to show Chen's components would be cheaper.
  • Patent owner's core merits theory (via Dr. DeLiang Wang / Dr. Anderson expert testimony): no reasonable expectation of success because Thelen's context-specific recognizers ported into Chen's clusters would cause memory collisions and degrade real-time operation.
  • No Motion to Amend appears on the public docket as surfaced. (Flagging uncertainty: I did not see a confirmed docket entry for a contingent MTA, so I do not assert one was filed or denied.)
• Settlement / termination: No settlement. Trial terminated by adverse judgment on the merits.
• Appeal: Yes. Zentian filed its Notice of Appeal on 2024-08-09, docketed at the Federal Circuit as No. 2024-2204 (Zentian Ltd. v. Apple Inc.), appealing the FWDs in both IPR2023-00033 and IPR2023-01192. Issues on appeal (per the § 90.2(a)(3)(ii) statement): the obviousness holdings over each reference combination, and whether substantial evidence supported them. Oral argument: 2026-06-04 (audio posted). Disposition: AFFIRMED, per curiam (Prost, Taranto, Cunningham, JJ.), Fed. Cir. R. 36, entered 2026-06-08 — a one-page nonprecedential order with no reasoned opinion. A Rule 36 affirmance leaves the PTAB FWD as the operative holding.
• Defensive value: Claim 46 is dead, and every claim litigated against Apple (46–51, 53, 54, 58, 59, 64, 67) is dead. Any infringement theory built on that set is unsupportable — you cite the FWD judgment page, not argue the merits.

IPR2023-01192 — [[Amazon.com Services](/litigations/by-defendant/Amazon.com%20Services) LLC](/litigations/by-plaintiff/Amazon.com%20Services%20LLC) & Amazon Web Services, Inc. v. Zentian Limited

• Type: Inter Partes Review, filed as a joinder to IPR2023-00033 under 35 U.S.C. § 315(c) / 37 C.F.R. §§ 42.22, 42.122(b)
• Filed: 2023-07-12
• Status: Final Written Decision - Appealed — joined to IPR2023-00033; all challenged claims held unpatentable; FWD 2024-06-11; appealed and affirmed.
• Judge panel: Same panel — Turner, Smith, Ogden (the joined proceeding shares the panel of the lead IPR).
• Petition grounds: Amazon's Petition is, by its own admission, "intentionally identical in substance to the Apple Petition" — the same four § 103(a) obviousness grounds against the same claims 46–51, 53, 54, 58, 59, 64, 67, relying on the Schmandt declaration and adopting it (Ex. 1043, Atlas declaration, ¶ 26).
• Institution decision: Instituted on all challenged claims and all grounds, and joinder granted, on 2024-01-10. The Board rejected Zentian's two discretionary arguments: (i) Fintiv factors 1–5 did not warrant denial (district trial set for 2024-09-23, months after the expected FWD); and (ii) a Sotera stipulation is not a prerequisite to institution — "denying institution merely because Petitioner has not entered a Sotera-style stipulation would be inappropriate" (citing Zhuhai Cosmx Battery Co. v. Maxell, IPR2022-00984, Paper 8). Amazon agreed to act as an "understudy" to Apple and cooperate in the joined proceeding.
• Final Written Decision: 2024-06-11 — the joined FWD (entered under the IPR2023-00033 caption with a footnote covering the joined Amazon parties) determined all challenged claims unpatentable on the same grounds, with the same Ogden majority / Smith dissent split.
• Settlement / termination: No settlement. Terminated by adverse FWD.
• Appeal: Yes — captured in the same Federal Circuit appeal, No. 2024-2204 (Zentian's Notice of Appeal expressly identifies "IPR2023-00033 / IPR2023-01192" and the 2024-06-11 FWD). Affirmed (Rule 36), 2026-06-08.
• Defensive value: Amazon is now both claim-dead and estopped. Two separate large-cap petitioners, and the Board still invalidated the whole asserted set — that is a strong signal that the asserted claim set is not defensible. Note however that Amazon's estoppel position differs from Apple's as a subordinate/joined petitioner (Network-1 Techs. v. Hewlett-Packard, 981 F.3d 1015).

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Strategic summary

Which claims are canceled vs. sustained vs. untested. On the FWD record, claims 46, 47, 48, 49, 50, 51, 53, 54, 58, 59, 64, and 67 are unpatentable — this includes independent claim 46 and its dependents, and it is the exact set Zentian asserted against both Apple and Amazon. No challenged claim was sustained. The remainder of the patent — claims 1–45, 52, 55–57, 60–63, 65, 66, 68, and 69 — was never before the Board and is therefore UNTESTED, not "upheld." Critically, four of the five other independent claims (1, 23, 45, 68, 69) were never challenged; only the claim‑45/46 "clustered memory" aspect was attacked. So if a letter cites claim 1, 23, 45, 68 or 69, there is no PTAB cancellation to point to — though the practical answer is that those claims expire with the patent term (adjusted expiration 2026-03-17, "Expired – Lifetime") and are of no ongoing commercial value.

Estoppel landscape. Under § 315(e)(2), Apple and Amazon (and their privies and real parties in interest) are estopped, as of the FWD, from asserting in the district court "any ground that the petitioner raised or reasonably could have raised" in the IPR. That locks out the entire Thelen + Bailey + Chen axis and its +Huang, +Jiang, and +Katz extensions, plus any variation a skilled practitioner could reasonably have raised. Two consequences: (a) in the stayed N.D. Cal. case, Apple cannot run Chen at all — a meaningful loss of defensive ammunition whose only cure was already consumed by the IPR win; and (b) apportionment of estoppel as between Apple and joined Amazon is not identical (Network-1). For a brand-new defendant, § 315(e)(2) estoppel does not bind you — you are free to run any prior art, including art listed in Amazon's exhibit file that was cited but never made a ground of institution (e.g., Hon, Ravishankar, Robinson, Wrench, Jelinek, Schmandt, Rabiner, Klevans, Young, Holmes, Nadas, Maes, Aoyama, Mariani). But an IPR would be pointless: the asserted claims are already held unpatentable and the patent has expired, so the correct posture is to plead the FWD as a complete defense/collateral-estoppel-style bar rather than file anything.

Pattern signals. Apple filed a five-petition family (IPR2023-00033 through -00037) covering the '319, '277, '377, '789 and '140 patents, and Amazon mirrored it with parallel joinders (IPR2023-01192 et seq.) — a coordinated, well-funded, multi-defendant invalidity campaign, not a Unified Patents / defensive-aggregator action (no aggregator appears anywhere in the chain). Zentian litigated aggressively: it opposed institution on Fintiv/Sotera grounds, ran a substantial reasonable-expectation-of-success defense with two experts (Wang, Anderson), and appealed (Notice 2024-08-09, No. 24-2204). It lost all of it — the appeal produced only a Rule 36 summary affirmance on 2026-06-08.

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Recommended next steps

1. If you are a defendant facing assertion of the '319 patent: cite the IPR2023-00033/01192 Final Written Decision of 2024-06-11 and its operative order verbatim — "ORDERED that claims 46–51, 53, 54, 58, 59, 64, and 67 of the '319 patent are unpatentable" — plus the Federal Circuit's Rule 36 affirmance, No. 2024-2204, 2026-06-08 (judgment PDF). If the demand letter asserts any of 46–51, 53, 54, 58, 59, 64, 67, it is asserting canceled claims. Full FWD: Docket Alarm copy of the 2024-06-11 Judgment; PTAB E2E: ptacts.uspto.gov; institution and joinder decision: IPR2023-01192 Paper 6 (2024-01-10); motion-to-amend/claim-history docket: Docket Alarm IPR2023-00033.
2. Flag the untested claims in your own risk memo. Coverage of independent claims 1, 23, 45, 68, 69 was never adjudicated. If a plaintiff pivots to those, PTAB estoppel gives you nothing directly — but the 2026-03-17 expiry and the "Expired – Lifetime" status mean there is no forward-looking injunction exposure and only the historical-damages window is live.
3. Do not expect a live appeal. No proceeding is active: both IPRs concluded 2024-06-11 and the appeal resolved 2026-06-08 by Rule 36. Unverified (search budget exhausted): whether any petition for rehearing/en banc/certiorari followed the 2026-06-08 judgment, and the current 2026 docket status of the stayed N.D. Cal. case 3:23-cv-02921-TLT (as of the 2024-06-25 stipulation it remained stayed during settlement talks). Confirm on PACER/CourtListener before relying on "final."
4. Data-hygiene warning for your files: at least one third-party AI summary (ai-lab.exparte.com) titles US 7,587,319 as "Speech Recognition System Having Parallel Large Vocabulary Recognition Engines." That is the title of the Thelen reference (US 6,526,380) — the art used to kill the patent — not the '319 patent. Do not import that error into a brief. The correct title is "Speech recognition circuit using parallel processors." Also, do not conflate the September 25, 2026 Zentian-v.-Apple nonprecedential opinion (which affirmed an IPR invalidating all claims of US 10,062,377, a different family member) with this patent; the '319 appeal is the June 8, 2026 Rule 36 order.

I'll research the assignment record and ownership chain for US 7,587,319, starting with the USPTO assignment reel/frame already visible in the patent's legal events.

I found the recorded assignment reel/frame. Now let me pin down the correspondent of record and check for any post-issuance transfers.

Let me locate the assignment's correspondent details and check whether Zentian appears on NPE/asserter directories.

I hit the search-step ceiling while confirming the correspondent field of the single assignment record, so I'll report what is verified and flag the one gap explicitly. Note: I also resolve an open item from the earlier "Patent summary" — the 2010‑09‑21 certificate of correction is now identified (see timeline).

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Inventors

Unusual-pattern check — no "inventor flight." The tell described in the brief (all inventors leaving the assignee within 12 months of filing, often preceding a portfolio fire‑sale) is absent:

• Catchpole has been a continuous Zentian director since 2000‑09‑07 and remains a PSC (Companies House no. 04054586).
• Guy Larri joined Zentian in 2004 and is also a current director/PSC, but he is not a named inventor on the '319 patent (he appears on the sibling '277 patent family). So there was never a cohort of '319 inventors to depart.

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Original assignee

Zentian Limited — UK private limited company, company no. 04054586, incorporated 17 August 2000, registered office 27 Queens Close, St Ives, Cambridgeshire, PE27 5QD. SIC 62090 (other IT service activities). Filed accounts show a micro‑entity (4 employees; equity ≈ £56,507 as of FY ended 31 Aug 2022). Officers include Catchpole, Larri, Paul Ernest Harding, Christopher Brian Turner; Julian Hildersley resigned 24 June 2021.

• Did it ship a product embodying the claims? No — and this is admitted. Zentian built "a partial prototype on a programmable hardware emulation platform" and an acoustic accelerator that gave a ~2× speedup of open‑source Sphinx, then pitched Nuance, IBM, Sensory, Samsung, Qualcomm, Hutchison 3G and Apple. The complaint states "Most of the work by Zentian was—and still is—unpaid, as funds proved difficult to raise" (6:22‑cv‑00123 ¶34). Third‑party profiles list total capital raised of only ~$150K. There is no evidence of any commercially shipped Zentian product.
• Primary line of business: speech‑recognition silicon IP / hardware accelerator design (start‑up R&D).
• Current status (as of today): Active — a confirmation statement was filed 20 Aug 2026 and accounts to 31 Aug 2024/2025 are on file. Not dissolved, not in bankruptcy, not acquired. It remains both the original and the current assignee of the '319 patent; it pleaded ownership itself ("Zentian is the owner of all rights, title, and interest in and to the '319 patent", Apple complaint ¶49).

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Assignment timeline

There is exactly one recorded assignment in the entire chain. Source: the '319 patent's own USPTO legal‑events record (Google Patents family block, fetched 2026‑09‑29), which is the same underlying record set served by the USPTO Assignment Center. There is no post‑issuance assignment, no security agreement, no merger, and no change of name recorded against US 7,587,319.

• 2004‑09‑09 (executed) / recorded 2005‑05‑24 — Reel 017053/0850
  • Conveyance: Assignment — "ASSIGNMENT OF ASSIGNORS INTEREST"
  • Assignor: Mark Catchpole (individual inventor)
  • Assignee: Zentian Limited (United Kingdom)
  • Correspondent: ⚠️ Not verified. I could not retrieve the correspondent/attorney field from the Assignment Center record for reel 017053/0850. The firm of record on the face of the '319 patent — and the firm that handled the 2010 PTA correspondence — is Dickstein Shapiro LLP, 1825 Eye Street NW, Washington, DC 20006‑5403 (attorney listed on the printed patent: Primary Examiner Daniel D. Abebe; Attorney, Agent, or Firm — Dickstein Shapiro LLP). I flag this as an inference about who likely filed the recording, not a confirmed correspondent entry. The sibling '140 patent later lists Finnegan Henderson Farabow Garrett & Dunner LLP as firm of record, so the family's US representation did shift over time.
  • Context: Founder‑to‑company assignment — the sole inventor conveying his rights to his own start‑up, executed during national‑stage entry. Not a fire‑sale, securitization, or transfer‑to‑asserter.

Other legal events on the patent (not assignments, listed for completeness):

• 2010‑09‑21 — Certificate of Correction. This resolves the open item in the earlier summary: it is a PTA recalculation under Wyeth, correcting the term extension from the printed 823 days to 1,137 days — which is what produces the recorded adjusted expiration of 2026‑03‑17. It does not appear to alter claim text.
• 2013‑03‑12 (4th yr), 2017‑03‑02 (8th yr), 2021‑03‑02 (12th yr) — maintenance fees paid; 12th‑year payment noted as small‑entity.
• 2023‑01‑10 / 2023‑08‑15 — IPR2023‑00033 (Apple) and IPR2023‑01192 (Amazon) filed; FWD 2024‑06‑11 holding claims 46–51, 53, 54, 58, 59, 64, 67 unpatentable (per the earlier sections).

If Assignment Center truly shows only this one record: that is itself the finding — the original assignee still owns the patent. Verify at assignmentcenter.uspto.gov by searching patent number 7587319, and the same record set at assignment.uspto.gov/patent.

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Timeline diagram

timeline
    title Ownership of US 7587319
    2000 : Zentian Ltd incorporated
    2002 : GB priority application filed
    2003 : PCT and US national stage filed
    2004 : Catchpole executes assignment
    2005 : Assignment recorded 017053 0850
    2009 : Patent issues as US 7587319
    2010 : Certificate of correction PTA 1137 days
    2022 : Zentian sues Apple and Amazon
    2024 : PTAB invalidates asserted claims
    2026 : Patent term expires

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NPE / troll-pattern signals

1. Shell-entity transfer — Not present. No movement to any "IP / Patents / Licensing / Holdings / Ventures" entity. The single recorded conveyance (reel 017053/0850) runs from the individual inventor to the original operating start‑up, not the reverse. Zentian's own registered address (27 Queens Close, St Ives) is a residential/small-office address, not a registered‑agent mail drop, and the company is a 26‑year‑old UK R&D company with directors who pre‑date the patent.
2. Known asserter in the chain — Not present as to the assignment chain. Neither Zentian Ltd nor any predecessor/link matches the Acacia, Marathon, IV, IPNav, Wi‑LAN, Conversant/Mosaid, Vringo, Pendrell, Innovatio, MPHJ, Lumen View, Round Rock, Document Generation or Spangenberg families. No assignee entity in the chain is on any such list; there is only one link and it is the original developer. (Zentian is a small serial plaintiff — two 2022 complaints against Apple and Amazon — but it asserts patents it developed, not patents acquired from a listed aggregator.)
3. Repeat correspondent across the chain — Unclear / not applicable to assignments. There is only one assignment link, so recurrence within the chain cannot exist. For cross‑family context only: the same litigation counsel recurs across the family's PTAB proceedings — Peter C. Knops and Kayvan B. Noroozi (Noroozi PC) and Katherine Rhoades / Nevin Gewertz (Bartlit Beck), served as practitioners of record for Zentian in IPR2023‑00033/‑01192. That is litigation representation, not assignment recording, so it is not a finding under this signal — a single firm doing both NPE and operating-company work is common; only recurrence in assignment recording would count, and none exists. ⚠️ The assignment correspondent for reel 017053/0850 remains unverified.
4. Cascading transfers — Not present. One assignment, executed 2004, recorded 2005; no chain. Zero assignments in the last 21 years.
5. Pre-litigation transfer — Not present. The sole assignment (executed 2004‑09‑09; recorded 2005‑05‑24) precedes the first infringement suits (filed 2022‑02‑02) by roughly 17 years. Nothing was arranged to set venue or manufacture standing; Zentian pleaded original ownership.
6. Bankruptcy fire-sale — Not present. No US Chapter 7/11, no assignment by an estate/trustee, no docketed sale proceeding. Zentian remains Active at Companies House with accounts filed in 2026.
7. Privateering — Not present. No operating company transferred this patent to a third-party NPE to assert on its behalf. The patent never left its developer; Zentian asserts in its own name. (Notably, the accused parties Apple and Amazon are the ones who approached/pitched against Zentian over the years, and Apple's Patent Acquisitions group met Zentian in 2015 — the inverse of privateering.)
8. Defensive aggregator (anti-NPE) — Not present. The chain does not terminate at RPX, AST, LOT Network, Unified Patents or OIN. (Careful: the Google Patents litigation block cites portal.unifiedpatents.com merely as a data source for the IPR/district docket links. The IPR petitioners are Apple Inc. and [Amazon.com Services LLC](/litigations/by-plaintiff/Amazon.com%20Services%20LLC) / Amazon Web Services, Inc. — Unified Patents is not a petitioner here and is not in the ownership chain.)

Weak signal that is present (worth naming): Zentian is a non-practising owner — no product in commerce, micro‑entity balance sheet, work admitted to be largely unpaid — yet it filed two litigations against large market participants (Apple; Amazon) asserting this patent. That is the substantive NPE characteristic. It simply does not travel with the assignment‑chain restructurings (shell LLCs, cascades, correspondent recurrence) that this analysis usually keys on, because the chain was never rebuilt.

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Verdict

NPE — moderate confidence.

The assignment record contains no shell entity, no cascading transfers, no pre-litigation transfer, and no known asserter — the only link is the founder-to-company conveyance at reel 017053/0850 (executed 2004‑09‑09, recorded 2005‑05‑24), and Zentian Ltd has owned the patent continuously since. The call rests instead on the substantive non-practice evidence: Zentian is a UK micro-entity (4 employees, ~£56.5K equity, no shipped product; 6:22‑cv‑00123 ¶34 admits the work was unpaid) that nonetheless filed suit against Apple (6:22‑cv‑00122 → N.D. Cal. 3:23‑cv‑02921) and Amazon (6:22‑cv‑00123) on 2022‑02‑02 — i.e., a genuine but commercially unsuccessful R&D company monetising its own portfolio through assertion, which is NPE conduct without the assignment-record signatures of an aggregation vehicle. I do not rate this high confidence because the defining chain-restructuring signals are affirmatively absent, and I could not verify the reel 017053/0850 correspondent to test for repeat-player recording.

Verification link: USPTO Assignment Center — search patent number 7587319 (record set also at assignment.uspto.gov/patent); patent-level legal events at patents.google.com/patent/US7587319B2/en.

Caveats: (a) the reel 017053/0850 correspondent field is unverified — do not treat Dickstein Shapiro LLP as the confirmed correspondent without pulling the record; (b) UK corporate data reflects Companies House filings through the 2026 confirmation statement; (c) no SEC filings exist for Zentian (private, non-US-listed), so that cross-reference is void rather than negative.

I'll search the USPTO and related databases for the exact patent and each cited reference.

Now let me search for the remaining cited references, including several that appear unrelated to speech recognition.

Prior Art Analysis — U.S. Patent No. 7,587,319 B2

Target confirmed (exact number, no substitution): US 7,587,319 B2, Speech recognition circuit using parallel processors, Mark Catchpole, Zentian Limited. Application US 10/503,463; PCT/GB2003/000459; priority 2002‑02‑04; filed 2003‑02‑04; granted 2009‑09‑08 (Google Patents; PubChem patent record US‑7587319‑B2). This is the only patent returned for that number; I did not return or substitute adjacent numbers.

Cross-reference note / contradiction flagged: The task states "Current Date: April 26, 2026," while my system date is 2026‑09‑29 and the earlier-generated sections of this analysis report a Fed. Cir. Rule 36 affirmance entered June 8, 2026. Per the prior sections' own flag, if the June 2026 event has not yet occurred on the working timeline, the appeal would be "argued but undecided." Nothing in this prior-art section depends on that dispute.

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1. What counts as "the patent citations for 7587319"

I treated the following as the references of record (the front-page "Patent Citations" and "Non-Patent Citations" listed on the '319 document, corroborated by the PubChem citation list):

• 17 patent documents (GB2112194A, US5995930A, US5293213A, US5881312A, US5832428A, US2001/0011218A1, GB2331392A, US6047283A, US2347835A, WO2000/050859A1, US7120582B1, US2003/0178584A1, US7174037B2, US7035802B1, GB2380920A, WO2003/067572A2, US2008/0255839A1).
• 10 non-patent citations (5 speech-recognition papers, 5 terahertz-imaging papers).

Important structural finding: the references that actually invalidated the asserted claims in the IPRs — Thelen US 6,526,380, Bailey US 5,459,798, Chen US 5,428,803, Huang US 6,076,056, and Jiang — are not in the '319 front-page citation list. They appear in the family's "Cited by Family" data and were petitioner-supplied art. Anyone treating the front-page citations as "the prior art that matters" will miss the dispositive art. I flag this because the earlier sections already noted the Office/PTAB outcome.

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2. Reference-by-reference analysis

A. References with genuine speech-recognition/architecture relevance

1. US 5,995,930 A — Häb‑Umbach, Reinhold & Ney, Hermann; U.S. Philips Corporation. Method and apparatus for recognizing spoken words in a speech signal by organizing the vocabulary in the form of a tree. Priority 1991‑09‑13 (DE 4130631); US filing 1996‑11‑18 (continuation chain back to 1992‑09‑14); granted 1999‑11‑30 (Google Patents).

• Description: Organizes the pronunciation lexicon as a vocabulary tree (each branch = a phoneme; each word = a branch junction/end); time-synchronous beam search with a threshold pruning all partial hypotheses; at each word end it stores a word result = word score + aggregate score, where the aggregate score is derived from a language-model value assigned to the completed word and a uniform-length string of prior completed words (n-gram), plus a reference to the predecessor word. Active trees/branches are maintained in linked lists so search cost is largely independent of vocabulary size.
• Potential §102 relevance: This is the closest of the cited patents to the lexical-tree and language-model-at-word-end concepts. It is squarely relevant to claim 2/24 (n‑phone model tree), claim 5/6/27/28/51/52 (language-model modification of results at a word-recognition event), claim 9/10/31/32/55/56 (history data including an accumulated score passed for a path), claim 12–13/34–35/58–59 (scores and pruning), claim 16/38/62 (pruning tree identifiers), and claim 18/40/64 (parameterized/feature input). It maps to the "lexical tree with common prefixes / unique initial component" element of claims 1(b)/23(b)/45/47/68.
• Caveat: US 5,995,930 describes a quasi-parallel time-synchronous search on a general apparatus; it does not disclose a plurality of lexical-tree processors wired in parallel with a results memory holding tree identifiers and a controller distributing work, so it cannot by itself anticipate claims 1, 23, 45, 46, 68, or 69.

2. US 7,035,802 B1 — Rigazio, Luca & Nguyen, Patrick; Matsushita Electric Industrial Co., Ltd. Recognition system using lexical trees. Priority 2000‑07‑31 (US 09/628,828); granted 2006‑04‑25 (EP counterpart EP 1 178 466 A2 published 2002‑02‑06) (Google Patents; Espacenet EP1178466).

• Description: A lexical-tree data structure encoded as a flat representation with nodes of each generation in contiguous memory; an "active node envelope" traversal algorithm replacing classic Viterbi bookkeeping; beam search; explicit discussion of HMMs, context-dependent (word-internal) models, one static lexical tree instance, and unigram/bigram language-model look-ahead.
• Potential §102 relevance (as §102(e) art, priority 2000‑07‑31): Directly relevant to claim 1(b)/23(b) (lexical data stored as lexical tree structures with common prefixes and a unique initial component), claim 2/24/48 (n‑phone model tree), claim 3/25/49 (monophone tree expanded into context-dependent models — note the IPR used the analogous Huang '056 for this), claim 4/26/50 (comparing parameters with lexical data to identify words), claim 12/13/34/35/58/59 (scores and beam pruning), claim 22/44/67 (HMM/Viterbi). Language-model look-ahead here supports the look-ahead pruning discussed in the '319 spec.
• Caveat: It is a single-processor software recognizer; it does not teach parallel lexical-tree processors, clustered memories, or a controller issuing tree identifiers from a results memory, so it does not anticipate claims 1/23/45/46/68/69 standing alone.

3. US 5,832,428 A — Apple Computer, Inc. Search engine for phrase recognition based on prefix/body/suffix architecture. Priority 1995‑10‑04; granted 1998‑11‑03 (Google Patents; Justia).

• Description: A speech-recognition search engine in which words are grouped into prefix/body/suffix classes and each class is organized into a lexical tree structure; a phrase-start lexical tree is built while preserving language-model connections; recognition uses probabilistic matching and dynamic programming (Viterbi) with an HMM acoustic model, guided by the language model.
• Potential §102 relevance: Relevant to claim 1(b)/23(b) (plurality of lexical tree structures modelling words with common prefixes), claim 4/26/50 (comparing speech parameters to lexical models to identify words), claim 18/40/64 (feature vectors from a front end), claim 22/44/67 (HMM/Viterbi search), and the general language-model guidance underlying claim 5/27/51.
• Caveat: It is a software search engine on a general-purpose processor with no parallel lexical-tree-processor hardware, no results memory storing tree identifiers, and no controller-driven work distribution — no anticipation of the independent claims.

4. US 5,881,312 A — Dulong, Carole; Intel Corporation. Memory transfer apparatus and method useful within a pattern recognition system. Priority 1993‑03‑18; granted 1999‑03‑09 (related U.S. 5,825,921, same title/assignee, filed 1995‑10‑23) (Google Patents; Unified Patents record).

• Description: A hardware memory-to-memory transfer unit with an automatic address sequencer, double buffering, and an internal multi-ported memory, allowing pattern data transfer to run in parallel with the arithmetic pipelines of a pattern-recognition engine (explicitly for voice or handwriting recognition), with the goal of hiding transfer latency from HMM/DTW processing.
• Potential §102 relevance: Relevant to the input-buffering / results-memory / memory-bandwidth architecture underlying claim 1(a),(d), claim 23(a),(d), claim 45/46 ("input buffer," "results memory"), and the '319 spec's own concern about memory-interface bottlenecks. It is background for why a POSITA would add a buffer and multiple local memories — the exact rationale the IPR petitioner used when combining Bailey '798.
• Caveat: It says nothing about lexical trees or parallel recognizer processors and cannot anticipate any claim.

5. US 2001/0011218 A1 — Steven Phillips. A system and apparatus for recognizing speech. Priority 1997‑09‑30; published 2001‑08‑02 (Google Patents).

• Description: A published application for a speech-recognition system/apparatus. I was not able to verify its detailed disclosure in this session, so I will not assert a specific §102 mapping beyond noting it is of-record background art published before the '319 priority date.
• Potential §102 relevance: Presumptively §102(b) prior art (published 2001‑08‑02, more than one year before the 2003‑02‑04 filing; though the critical date is the 2002‑02‑04 priority, it still predates priority). Unverified as to specific claim limitations.

6. GB 2 331 392 A — International Business Machines Corp. Fast vocabulary‑independent spotting of words in speech. Priority 1997‑10‑15; published 1999‑05‑19 (Google Patents).

• Description: Vocabulary-independent word spotting. Verified only at the bibliographic level in this session; does not appear to be relied upon for any specific limitation in the IPRs.
• Potential §102 relevance: Weak. At most background on search/knowledge within a general-purpose recognizer; no parallel-processor or lexical-tree-processor disclosure identified.

7. US 6,047,283 A — SAP Aktiengesellschaft. Fast string searching and indexing using a search tree having a plurality of linked nodes. Priority 1998‑02‑26; granted 2000‑04‑04 (Google Patents).

• Description: Text/data string searching and indexing with a linked-node search tree.
• Potential §102 relevance: Marginal — it is a text retrieval/prefix-tree reference, not speech. It could only be cited as generic evidence that tree-structured lexicons with pointer/nodelinks were known. It does not anticipate any '319 speech claim and would not be a serious §102 reference.

8. US 7,120,582 B1 — Dragon Systems, Inc. Expanding an effective vocabulary of a speech recognition system. Priority 1999‑09‑07; granted 2006‑10‑10 (Google Patents).

• Description: Techniques for enlarging the effective vocabulary of a recognizer (vocabulary expansion/backoff). I did not verify the detailed disclosure in this session.
• Potential §102 relevance: Possible §102(e) art as to large-vocabulary handling and language-model augmentation; no identified disclosure of parallel lexical-tree processors, clustered memories, or controller-distributed tree identifiers. Not a candidate to anticipate claims 1/23/45/46/68/69.

9. GB 2 112 194 A — National Research Development Corporation (UK). Recognition apparatus. Priority/filed 1981‑11‑27; published 1983‑07‑13 (Google Patents).

• Description: An early British recognition apparatus. I was unable to verify the technical content in this session; it is of-record but predates the '319 priority by two decades.
• Potential §102 relevance: At most general background on pattern/speech recognition apparatus. No basis in the record examined to map it onto any '319 claim. Unverified.

10. GB 2 347 835 A / US 5,293,213 A / WO 2000/050859 A1 / US 2003/0178584 A1 / US 7,174,037 B2 / GB 2 380 920 A — Terahertz-imaging references.

• Citations: GB2347835A, "Terahertz radiation imaging" (Toshiba Research Europe), priority/pub 1999‑02‑23 / 2000‑09‑13; US5293213A, "Utilization of a modulated laser beam in heterodyne interferometry" (Klein), 1992‑08‑12 / 1994‑03‑08; WO2000050859A1, "Method and apparatus for terahertz imaging" (Teraprobe Limited), 1999‑02‑23 / 2000‑08‑31; US20030178584A1, "Imaging apparatus and method" (Arnone), priority 2000‑02‑28, published 2003‑09‑25; US7174037B2, "Imaging apparatus and method" (Teraview Limited), granted 2007‑02‑06; GB2380920A, "Terahertz radiation imaging" (Teraview Ltd), 2001‑09‑12 / 2003‑04‑16 (Google Patents family citation list).
• Description: All six relate to terahertz/laser imaging and spectroscopy (biomedical imaging, heterodyne interferometry) — an entirely different technical field.
• Potential §102 relevance: none for any claim 1–69. These appear to be citation-record contamination (the same terahertz references recur in the Zentian family's citation data and in the NPL list; see the "Terahertz Imaging of Breast Cancer" etc. items). I am flagging this explicitly rather than constructing artificial relevance. If you need to know how they entered the record, the answer is almost certainly an IDS/citation‑list artifact; that cannot be confirmed from the patent text alone.

B. Self-citations (family members, not prior art)

11. WO 2003/067572 A2 — Zentian Limited. Speech recognition circuit using parallel processors. Priority 2002‑02‑04; published 2003‑08‑14 — this is the PCT parent of the '319 itself (PCT/GB2003/000459), published after the '319 priority/filing date. Not prior art; it is the same invention.

12. US 2008/0255839 A1 — Zentian Limited. Speech Recognition Circuit and Method. Priority 2004‑09‑14; published 2008‑10‑16 — a later related Zentian application (GB 0420464.0 family), published long after the '319 filing date. Not prior art to the '319.

C. Non-patent citations (principally background / §102(b) printed publications)

Speech-recognition NPL (relevance to the parallel concept):

• Deshmukh, N. et al., "Hierarchical Search for Large-Vocabulary Conversational Speech Recognition," IEEE Signal Processing Magazine, vol. 16, no. 5, Sep. 1999, pp. 84–107 — expressly incorporated by reference into the '319 description (background on HMM/Viterbi breadыth-first search). §102(b) printed publication; describes the search problem the '319 addresses, but not the parallel-processor architecture.
• Chatterjee, S. et al., "Connected Speech Recognition on a Multiple Processor Pipeline," ICASSP 89, 1989‑05‑23, pp. 774–777.
• Glinski, S. et al., "Spoken Language Recognition on a DSP Array Processor," IEEE Trans. Parallel and Distributed Systems, 1994‑07‑05, no. 7, pp. 697–703.
• Chung, S‑H. et al., "A Parallel Computational Model for Integrated Speech and Natural Language Understanding," IEEE Trans. Computers, vol. 42, no. 10, 1993‑10‑01, pp. 1171–1183.
• Chung, S‑H. et al., "A Parallel Phoneme Recognition Algorithm Based on Continuous Hidden Markov Model," Proc. 13th IPPS / 10th SPDP, 1999, pp. 453–457.
  • These four are the NPL sources relevant to claim 1(c)/23(c)/45/46 (parallel processing of speech parameters). They are the kind of art that supports an obviousness attack (static partitioning of a lexical network among processors, as the '319 background itself concedes regarding Ravishankar and Dujari), but none is identified as disclosing the dynamic, controller-distributed, results-memory-driven tree allocation recited in the independent claims.
• Terahertz NPL: Fitzgerald et al. (2004), Cole et al., Woodward et al. (2004), Wallace et al. (2002), Wallace et al. (2004). Field-irrelevant; no §102 relevance to any claim.

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3. Consolidated §102 assessment

Bottom line on the front-page citations: none of the 17 patent citations anticipates independent claims 1, 23, 45, 46, 68, or 69 under §102. Their real value to a challenger is (i) as §103 combination material (e.g., Philips '930 for lexical trees + language models, Matsushita '802 for lexical-tree search/LM look-ahead, Intel '312 for buffered parallel memory architectures, and the parallel-DSP NPL for parallelization), and (ii) as §102 art against individual dependent-claim concepts if the independent-claim elements are supplied elsewhere.

The art that actually decided the case (and which is not in the '319 front-page list) is the §103 combination the PTAB adopted: Thelen US 6,526,380 + Bailey US 5,459,798 + Chen US 5,428,803, with Huang US 6,076,056 (claims 47–49) and Jiang (claims 53, 58–59) — holding claims 46–51, 53, 54, 58, 59, 64, 67 unpatentable in IPR2023‑00033 (Apple) and the joined IPR2023‑01192 (Amazon), FWD 2024‑06‑11 (IPR2023‑00033 summary; IPR2023‑01192 case page). That combination is a §103 ground, not §102 anticipation, and it targets the clustered-memory independent claim 46 rather than claims 1/23/45/68/69.

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4. Explicit caveats

1. Verification limits: I could not retrieve the detailed disclosures of GB2112194A, US2001/0011218A1, GB2331392A, US6047283A, or US7120582B1 in this session. My §102 statements about them are marked "unverified" and should not be relied upon without pulling the documents.
2. No single-reference anticipation found for any independent claim among the references of record. I say this rather than manufacturing a §102 mapping, because §102 requires every element in one reference.
3. Terahertz contamination is reported as-is; I did not attempt to force relevance for those six patents or five NPL items. Whether they entered the '319 record via an IDS error or a citation-aggregation artifact cannot be determined from the patent text alone.
4. The IPR/PTAB art (Thelen, Bailey, Chen, Huang, Jiang) is the dispositive art but is not part of the '319's own front-page citation list; it is family-citation data. This is consistent with the earlier-generated sections and should be read together with them.
5. Date inconsistency flagged (April 26, 2026 per task vs. 2026‑09‑29 system date and the June 8, 2026 CAFC event reported earlier). It does not affect any prior-art mapping above, all of which turns on dates in 1981–2003.

I'll verify the identities of the key prior-art references before mapping them onto the claims.

Obviousness Analysis — U.S. Patent No. 7,587,319 B2

"Speech recognition circuit using parallel processors" (Catchpole; Zentian Ltd.)

Basis and continuity. This builds on the bibliographic, claim-structure, and litigation sections already produced and does not repeat them. The PTAB adjudication (IPR2023‑00033 / IPR2023‑01192, FWD 2024‑06‑11; affirmed Fed. Cir. No. 2024‑2204, June 8, 2026, Rule 36) supplies a binding §103 outcome for the challenged claims; the analysis below therefore concentrates on the unadjudicated claims (1–45, 52, 55–57, 60–63, 65–66, 68, 69), using the references appearing on the '319 patent face (its own "Prior Art"/Citations section) plus the petition record.

Date flag (carried forward). The task header states April 26, 2026, while the record I retrieved contains a June 8, 2026 Rule 36 judgment in No. 2024‑2204. I report the search results as ground truth per instructions; the discrepancy does not affect the §103 substance below, because the PTAB's June 11, 2024 FWD is the operative merits decision either way.

Data-integrity flag. The Google Patents "Prior Art" section for the '319 patent is internally contaminated: it interleaves terahertz-imaging references (US 5,293,213 Klein "laser beam heterodyne interferometry"; GB 2,347,835 and WO 00/50859 and GB 2,380,920 (Teraview/Toshiba); US 2003/0178584 and US 7,174,037 Arnone; and the Fitzgerald / Cole / Woodward / Wallace THz NPL papers) that have no bearing on speech recognition. These appear to be artifacts of the shared "GB 2,38x,xxx" numbering and a merged citation list, not genuine §103 art. I discard them. Likewise, at least one AI-generated PTAB summary titles the '319 patent with the Thelen title ("Speech Recognition System Having Parallel Large Vocabulary Recognition Engines") — wrong; the '319 title is as stated above.

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1. Legal framework applied

• Graham v. John Deere, 383 U.S. 1 (1966): scope/content of prior art; differences; level of ordinary skill; secondary considerations.
• KSR Int'l v. Teleflex, 550 U.S. 398 (2007): a combination is obvious where (a) elements are known, (b) combined "according to known methods," (c) yielding "predictable results"; mere "obvious to try" suffices where the design space is finite and the outcome predictable; design incentives and market/engineering pressures count.
• In re Keller, 642 F.2d 413 (CCPA 1981): obviousness is judged on the combination, not on each reference alone.
• 35 U.S.C. §112(f): claims 1, 23 (and 45) recite "input means," "lexical memory means," "results memory means," "control processor means," "receiving means." These are means-plus-function limitations, construed to cover the corresponding structures disclosed in the specification (input buffer 20; acoustic model memories 23; results memory 25; search controller 27; language model processor 29) and equivalents. This limits the literal scope but does not confer patentability where the underlying structures are known.
• POSITA level of skill (adopted by the Board): master's in computer/electrical engineering or CS with ~2 years' speech-recognition experience, or bachelor's with ~4 years. Notably, the Board did not require IC-fabrication expertise — a point Zentian pressed and lost.

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2. The prior-art universe actually on the '319 face

2.1 Speech-recognition art cited in the patent (usable §103 art)

Caveat: several 2006-parent and later Zentian-family items (e.g., US 2008/0255839) and the 2008-priority NEC LM-look-ahead publication in the "Cited By" list are not prior art and are excluded.

2.2 Non-patent literature cited on the face

• Deshmukh et al., Hierarchical Search for LVCSR, IEEE SP Mag. (Sept. 1999) — Viterbi/beam search over lexical trees; LM look-ahead. (Expressly incorporated by reference in the '319 specification.)
• Ravishankar, Parallel Implementation of Fast Beam Search… (1993) — multi-threaded beam search; "[t]he single largest source of computational efficiency" is organizing HMMs as a phonetic tree.
• Chatterjee et al., Connected Speech Recognition on a Multiple Processor Pipeline, ICASSP‑89.
• Glinski et al., Spoken Language Recognition on a DSP Array Processor, IEEE TPDS (1994).
• Chung et al., A Parallel Computational Model for Integrated Speech and Natural Language Understanding, IEEE Trans. Computers (1993); and A Parallel Phoneme Recognition Algorithm Based on Continuous HMM (1999).

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3. What the Board already decided (do not re-litigate)

Claims 46–51, 53, 54, 58, 59, 64, 67 were held obvious over Thelen + Bailey + Chen (Ground 1), with Huang added for 47–49 (Ground 2) and a further reference (record lists Jiang, and a Katz reference in the Amazon petition, whose identities I could not fully verify) for 53/58–59. The Board's core holdings transferable to the claims below:

1. Thelen supplies "in combination complete lexical data" split into parts + a controller distributing input to parallel recognizers.
2. Bailey supplies the input buffer, the results memory (RAM 512 + interrupt-driven result transfer), per-engine private memory, and Viterbi-over-HMM — and explicitly motivates a data buffer that decouples feature-vector generation from recognition for efficiency.
3. Chen supplies groups of processors each with a shared memory, and is properly treated as art "reasonably pertinent" to the parallel-search problem despite being a general parallel-processing reference (In re Clay).
4. Huang supplies the prefix tree (unique first-phone branch), monophone→triphone dynamic generation, beam pruning, and trigram LM scoring at word ends.

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4. Ground-by-ground §103 analysis of the unadjudicated claims

GROUND A — Claims 1, 23 and method claim 68

Combination: Thelen + Bailey + Chen + US 5,995,930 (Philips) and/or US 7,035,802 (Matsushita) and/or Huang, optionally + Deshmukh.

Motivation. Thelen states the operative pressure itself: real-time recognition in which "no significant delay occurs." Bailey supplies the express efficiency rationale for an input buffer (decoupling feature generation from recognition). Chen supplies an enabled clustered architecture that "does not have to sacrifice performance" for expanded interconnections. Deshmukh/Ravishankar/Huang establish that the accepted way to make LVCSR tractable is a lexical/prefix tree plus pruning, and that word-end hypotheses naturally identify the next trees to expand. Combining these is element-by-element application of known techniques.

Defensible gap to note. Claim 1's requirement that the results memory itself store tree identifiers as a work queue is the feature not squarely litigated. A Patent Owner could argue no single reference stores next-tree IDs in the results memory as such; but the combination of Bailey's results memory with the pointer-linked tree of US 6,047,283 and the word-end spawning of US 5,995,930/Deshmukh makes this a predictable, if narrow, design choice. Confidence: moderate-to-high for the combination; moderate as to claim 1's work-list limitation specifically.

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GROUND B — Claim 45, method claim 69, and claims 60–63, 20–21, 42–43, 66

Combination: Thelen + Bailey + Chen (+ Deshmukh/Ravishankar for multi-tree processing).

• Clustered processor/memory architecture and partial-lexicon distribution: Chen (clusters 100a–d with shared memories 104a–d) as applied to Thelen's context-partitioned models; already the Board's Ground 1 logic.
• "Processors use lexical data corresponding to more than one lexical tree at the same time" (claims 45, 60): taught/predicted by Ravishankar's multi-threaded beam search, by Chung's parallel HMM recognition of multiple hypotheses, and by the ordinary practice of a processor keeping several active hypotheses (Huang's active-hypotheses after prefix-tree traversal). A processor with spare throughput running a second tree is a predictable use of known capacity, squarely within KSR.
• Claims 20/21/42/43/66 (partial memory per group or per processor): Thelen's per-context model partitioning + Bailey's per-engine private memory 615a–c + Chen's cluster-shared memory. Board already so held for 42/43.

Motivation. Chen's own text supplies the cost/efficiency story: sharing cluster memory reduces duplication of lexical data and cost while preserving parallelism; Thelen supplies the model-partitioning rationale.

Confidence: high for 45/69 and 60–63 (they are the same subject matter as adjudicated 46–49 plus the ">1 tree" feature), high for 20–21/42–43/66.

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GROUND C — Claims 2/3, 24/25, 48/49, 40–41/64–65 (model granularity; feature vectors; n-phones)

Combination: Ground A/B base + Huang.

• n-phone / mono-phone trees: Huang teaches monophone models used to dynamically generate triphones (context-dependent) — directly the claim 3/25/49 feature, and the Board already held claims 48/49 unpatentable on exactly this basis.
• Feature vectors (18/40/64) and n-phones as input (19/41/65): Bailey/Thelen operate on parameterized frames; 64 already held unpatentable; 18/40 identical in substance.

Confidence: high.

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GROUND D — Claims 4–8, 26–30, 50–54 (comparison, word-recognition events, LM scoring)

Combination: Thelen + Bailey + Chen + Huang (+ a language-model reference).

• Compare parameters against lexical data and signal a word recognition event: Bailey (pattern comparison → interrupt on completion) — the Board's ground for claim 50.
• LM output modifying the recognition result: Huang applies a 60,000-word trigram language model after prefix-tree traversal; Deshmukh teaches LM look-ahead at word ends; Thelen's controller uses a "language model" per recognition model (Thelen, 7:30–40). This covers claims 5/6/27/28/51 and claim 52 (LM output received and modified result written back to results memory) — Bailey's interrupt-driven results transfer supplies the write-back path.
• Scores for words at word-recognition events (7/29/53): Thelen's and Huang's Viterbi scores.

Confidence: high (52 is a two-reference fix-up over the already-adjudicated 51).

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GROUND E — Claims 12–17, 34–39, 58–59, 62–63 (scoring during processing, pruning, controller-determines/prunes next trees)

Combination: Huang (beam-search threshold pruning; "active hypotheses"; prefix tree) + Deshmukh (hierarchical/beam search, LM look-ahead pruning) + US 5,710,866 (dynamically adjusted confidence threshold) + Chen/Thelen (controller selecting next models) + US 6,047,283 (tree node IDs).

• Pruning in dependence on determined scores: Huang expressly; 58/59 already held unpatentable.
• Controller determining new tree identifiers for words identified and pruning them (15–17, 37–39, 61–63): Thelen's controller/model selector selecting which models to activate (including its "test models in background, enable if better" logic — a bound-based selection), combined with US 5,710,866's dynamic threshold. Semantic equivalence to the claimed pruning is strong; the only nuance is whether the pruning is controller-side vs. processor-side, which claims 15–17/37–39/61–63 place in the controller.

Confidence: high for 12–14/34–36/58–59; moderate-to-high for 15–17/37–39/61–63.

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GROUND F — Claims 9–11, 31–33, 55–57 (controller passes tree ID + history data incl. accumulated score; processor reads tree)

Combination: Bailey (CPU 510 "splits the processing work" among PR engines and passes each the unknown pattern; per-engine memory) + Thelen (controller directs input to recognizers) + Huang/Deshmukh (Viterbi path score = accumulated score; N-best hypothesis histories) + US 6,047,283 (node identifiers for tree traversal).

Motivation. Distributing work by handing each processor an identifier of the unit of work plus its current state is the everyday mechanism of parallel search; Bailey's CPU-level work splitting and Chen's clustered scheduling make it routine.

Confidence: moderate-to-high. The "history data for a recognition path … including an accumulated score" is the sort of conventional Viterbi bookkeeping Huang/Bailey disclose, but no reference was shown (in the IPRs) to store that history in a shared results memory for redispatch.

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GROUND G — Claims 22/44/67 (HMM + Viterbi)

Combination: Thelen (HMM-based recognition models) + Bailey ("Viterbi score procedure … on HMMs") + Huang (HMM/Viterbi over prefix tree). Claim 67 already held unpatentable.

Confidence: high.

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5. Consolidated KSR motivations (why a POSITA would combine)

1. Art-recognized problem + finite design space. LVCSR search is "computationally intensive" (the '319 specification concedes this; Deshmukh, Ravishankar, Chung, Chatterjee, Glinski all address parallelizing it). Where the art converges on parallel processors + lexical trees + pruning, the specific arrangement claimed is an engineering selection, not an inventive leap (KSR).
2. Express real-time pressure. Thelen: recognition in "real time … no significant delay"; Bailey: "real-time responses of at most 0.1 seconds … fully user interactive." Both supply the why for parallel search.
3. Express efficiency rationale for the buffer. Bailey teaches a buffer to decouple feature generation from recognition — the same rationale the '319 specification gives for buffer 20.
4. Express rationale for clustered shared memory. Chen teaches grouping processors with shared memory and balancing parallel performance against interconnect cost — exactly the '319 patent's stated advantage over both a single global memory and strictly private per-processor memories.
5. Express rationale for trees. Ravishankar: phonetic-tree organization is "the single largest source of computational efficiency"; Huang: prefix sharing; US 5,995,930/US 7,035,802: tree-organized lexicons.
6. Predictable results, no new mechanism. Every claimed element performs its established function (buffer buffering, memory storing, processor processing, controller controlling). KSR at 417 ("familiar elements … according to known methods").
7. The Board's anti-hindsight reasoning applies with equal force here: the claims recite architecture, not the memory-collision/real-time implementation details Zentian argued were beyond skill — and the '319 specification itself discloses none of those details.

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6. Secondary considerations / rebuttal

• I found no evidence of unexpected results, long-felt need, industry praise, licensing-due-to-merit, or copying attributable to the '319 claims. The patent expired (adjusted expiration 2026‑03‑17) and the asserted claims (46–51, 53, 54, 58, 59, 64, 67) were cancelled. Zentian's IPR arguments (teaching away, "too complex," non-analogous art, "common sense" impermissible under Arendi/Van Os/FanDuel) were rejected at institution and lost at final written decision, and were not disturbed on appeal.
• The most credible non-obviousness hooks remaining are (a) the results-memory-as-work-queue limitation of claim 1, and (b) the history data incl. accumulated score passed by the controller of claims 9/31/55. Both are narrow and, in my view, likely surmountable with US 6,047,283 + Bailey + Huang, but no tribunal has so held.

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7. Bottom line

Overall: the '319 patent's independent claims are, on the prior art cited on its own face and in the IPR record, obvious under §103 in the Thelen + Bailey + Chen (+ Huang) combination, with the clustered-architecture claims (46 et seq.) already finally adjudicated as such. The residual uncertainty is confined to the narrow "results-memory stores tree identifiers" and "controller passes path history/accumulated score" limitations in claims 1/9/31/55/68, which I could not find squarely litigated.

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8. Explicit caveats

1. I could not verify the identity/contents of the "Jiang" and "Katz" references used in the IPRs for claims 53, 58–59; my mapping of those dependent claims relies on the petition's own summary, not the primary text.
2. The "Prior Art" section of the Google Patents page for this patent is contaminated with terahertz references (§0 above). Any downstream use of that citation list must filter them out.
3. I have not retrieved the 2010‑09‑21 certificate of correction, so claim text is taken as it appears in the authoritative granted copy.
4. Claim-number precision matters: I have kept the '319's claims distinct from the related '277, '377, '789 and '140 patents throughout. The September 25, 2026 Zentian v. Apple nonprecedential affirmance concerns the '377 patent (all claims unpatentable), not the '319.