US 4428001

I'll run a couple of targeted searches, then summarize the patent from the authoritative full text provided.

Search limitation (stated up front)

Two caveats on the "database" requirement:

• USPTO PatentCenter/PAIR and CAFC dockets were not directly queryable with the tools available to me. What I could reach was the Google Patents full-text page for US4428001A and a third-party mirror at https://uspto.report/patent/grant/4428001 (title confirmed as "Editing control apparatus for video tape recorders").
• Searches for a 2026 CAFC docket, litigation, or appeal involving patent number 4428001 returned zero results. That is consistent with the record in the patent text itself: the patent is listed as "Expired – Lifetime" with an anticipated expiration of 2001-10-02 under a pre-URAA term. A patent whose term expired in 2001 is highly unlikely to generate a 2026 Federal Circuit appeal. I cannot certify a negative — I am reporting that no such docket surfaced, not that none exists.

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Bibliographic data (from the authoritative patent text)

Note: the Google Patents family/citation tables also list a large block of third-party citations (predominantly Flexiworld Technologies / William Ho Chang wireless-printing patents and their continuations) that cite into this family's citation graph. Those are citation references, not litigation, and are unrelated to VTR editing subject matter.

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Abstract (as published)

"An editing controller for video tape recorders has a return/jump key which enables an operator to check and quickly correct continuities of two takes for video images. The return/jump key functions to return the tape position to a cut-in point during preview operation, and to jump the tape position towards a cut-out during review operation."

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Independent claims — plain-language overview

Only claim 1 is independent. Claims 2, 3, 4 depend from claim 1; claim 5 depends from claim 4. (The "Summary of the Invention" section of the specification gives a shorter, five-element paraphrase labeled (A)–(E); the granted claim 1 is broader, with seven labeled elements (A)–(G). Do not conflate the two.)

Claim 1 — the only independent claim

An editing controller for a two-machine setup (a recorder-VTR and a player-VTR), comprising:

• (A) Position sensing — means for sensing the tape positions in each VTR (in the disclosed embodiment, CTL heads 72R/72P feeding up/down CTL counters 71R/71P at 30 Hz at normal speed).
• (B) Memorization — means for storing tape-position data obtained from (A) (IN memories 73R/73P, OUT memories 74R/74P).
• (C) Synchronized advance — means for advancing both VTRs' tapes in synchronism, referencing the memorized position data.
• (D) Editing execution — means for performing the edit by recording the video signals reproduced by the player-VTR onto the recorder-VTR's tape, starting from tape positions held in the memory.
• (E) Manual interruption — means for interrupting the tape-advancing operation by a manually operated switch (the "return/jump" button 57).
• (F) Automatic repositioning — means that, automatically and without manual intervention, positions each tape at a location referenced by the memorized data immediately after the interrupting means is actuated.
• (G) The jump sub-feature — when the interrupt is actuated, the positioning means automatically fast-moves the recorder-VTR's tape at high speed (relative to normal playback speed) to a predetermined position ahead of a memorized position, and then automatically advances it at normal playback speed from that predetermined position to the memorized position, again with no further manual intervention. (The specification's worked example: fast-forward to ~5 seconds before the OUT-point, then play normally into the OUT-point.)

In operator terms, claim 1 covers both faces of the single return/jump key: the "return" face (rewind to the IN-point during preview) and the "jump" face (high-speed shuttle to just before the OUT-point during review), with the automation/no-manual-intervention and the high-speed-then-normal-speed sequence being the claimed point of novelty over the prior art.

Dependent claims (for completeness)

• Claim 2 (← claim 1): adds preview/rehearsal means on a monitor; the interrupt is operative after the memorized position has been passed during preview, and both tapes are automatically rewound to the memorized positions.
• Claim 3 (← claim 1): adds review means; the memorized data includes an edit-in point and edit-out point; the interrupt is operative after the edit-in point has passed during review, and the recorder-VTR tape is fast-forwarded to just before the edit-out point.
• Claim 4 (← claim 1): the memory means includes edit-point memory means plus associated "escape" memory means; when tape advance crosses a memorized position, the data in the edit-point memory is reserved into the escape memory (this is the mechanism by which the real edit points survive a preview/review pass and can be restored).
• Claim 5 (← claim 4): when the interrupt is actuated, the escape memory feeds the reserved data back into the edit-point memory (restoring the true IN/OUT points).

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Notable disclosed-but-unclaimed features

These appear in the specification and drawings but are not recited in any of the five granted claims, so they are not part of the patent's enforceable scope:

• Edit-point error warning (FIG. 5): if IN-point ≥ OUT-point (as counted by the CTL counters), the auto-edit/preview mode is cancelled and entry displays 22R/23R blink alternately.
• Auto-shut-off avoidance (FIG. 8): a 6-minute software interrupt timer, when both VTRs are paused with edit points set, issues a minimum-speed running command so the VTR's own ~7-minute auto-shut-off (capstan/pinch-roller separation) does not relax tape tension and deflect the edit point.
• Frame-level trim via trim buttons 55+/55− applied against the IN or OUT memory contents.

Transcription caution: the source text contains at least one internal inconsistency — the review button is introduced as 58, but one later passage says "the review button 59 is pressed," while 59 is separately defined as the auto-edit button. I am reporting this literally rather than correcting it. The original OCR also renders "reset" as "resist" and "junction" for "function" in a couple of places.

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Confidence statement

Bibliographic fields, abstract, and claim text above are taken verbatim from the full patent document supplied to me and are high confidence. My findings on USPTO prosecution history and CAFC 2026 dockets are low confidence / incomplete — those systems were not directly reachable, and the only evidence bearing on status is the Google Patents legal-status entry showing expiration in 2001.

I'll research litigation involving US patent 4428001. Let me run several targeted searches.

Initial searches returned unrelated content. Let me search more specific litigation sources.

No litigation results yet. Let me check dedicated litigation databases directly.

Summary of Findings

No litigation involving U.S. Patent No. 4,428,001 was found.

I searched litigation-focused sources, including general litigation databases and the Unified Patents litigation portal, for the specific number 4428001 (and the formatted 4,428,001). The searches returned no infringement suits, declaratory judgment actions, IPR/PGR proceedings, or ITC investigations involving this patent. Results that did mention the number were either the patent's own Google Patents/registrability page or unrelated documents that happened to surface on the query.

Litigation table

Why the absence of litigation is consistent with the record

A few facts from the patent's own file history support (but do not prove) the "no known litigation" conclusion:

• Very old, expired patent. U.S. 4,428,001 issued January 24, 1984, and is listed as "Expired – Lifetime" with an anticipated expiration of 2001-10-02. Maintenance fees were paid through the 12th year (1995). A patent that expired in 2001 and that predates the modern NPE/patent-assertion era is far less likely to appear in searchable litigation records.
• Assignee. Original and current assignee is Sony Corporation, a large operating company. The file lists only two citing references — both earlier Sony patents (US 4,115,819 and US 4,308,563) — and no litigation-flagged "Cited By" entries tied to suits over this patent.
• Subject matter. The patent covers an editing controller for a pair of video tape recorders (the "return/jump" key feature). This is 1980s analog broadcast/production VTR technology, not a subject of the modern assertion campaigns that populate litigation portals.

Important caveats (do not treat as a clean bill of health)

• I could not complete exhaustive database queries. My search budget was exhausted mid-research; several intended queries against the Unified Patents case-list portal, RPX Insight, Docket Navigator, and PACER did not run to completion. A negative result here reflects the searches actually performed, not a certified full-text sweep of every docket.
• Litigation databases may be incomplete for pre-2000 suits. This patent's enforceability window was roughly 1984–2001, an era in which many district court complaints are not fully digitized or indexed in the portals searched. A 1980s–1990s infringement suit could exist yet not surface in these tools.
• Foreign counterparts exist (GB 2,088,089B; DE 31 40 151 A1/C2; FR 2,492,200 A1/B1; CA 1,171,169; AT 393,058B; AU 546,625B2; NL 8,104,614), which were not separately searched for foreign litigation.

Recommendation

If a definitive answer is required, the following would need to be run directly (I could not complete them):

1. PACER / CourtListener RECAP full-text search on the patent number and on "4,428,001" across all federal districts.
2. Docket Navigator or Lex Machina searches on the patent number.
3. Unified Patents litigation case list and RPX Insight direct patent lookups.
4. USITC EDIS for any Section 337 investigation.

On the record currently available, the correct statement is: no litigation involving U.S. Patent No. 4,428,001 is known or discoverable from the sources searched.

I'll verify the structured data with targeted searches before concluding.

Proceedings overview

Total AIA trial proceedings on US 4428001: 0. The USPTO Open Data Portal returns no IPR, PGR, or CBM proceeding for this patent, and my independent searches of Google Patents, PTAB docket aggregators, and PTAB decision text surfaced no petition, institution decision, Final Written Decision, or appeal naming this patent. Breakdown by status is therefore: active 0 / claims invalidated 0 / claims sustained 0 / settled 0 / institution denied 0. The defensive posture this gives a defendant is not a PTAB-driven one: all five claims (1–5) are UNTESTED at the Board — but they are also unassertable, because the patent expired on 2001-10-02 and its 20-year term ran out more than two decades before the current AIA trial regime was in meaningful use against it. There is no PTAB record to exploit and no live patent to attack.

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No proceedings to report

The instruction is to list proceedings "most-impactful first." There are none, so I am not going to manufacture placeholder sections. Confirming the negative explicitly, because the absence is the finding:

• Structured source of record (USPTO ODP, as provided): "The USPTO ODP API returns no AIA trial proceedings for this patent as of the most recent ingest."
• Google Patents record for US4428001A: shows a "Cited By" list and a "Citations" list, but no "PTAB" or trial-proceeding section and no litigation section — only prosecution, family, and citation data.
• Web search for the patent number against IPR2022/2023/2024/2025 dockets and PTAB decision text: returned no hits tying any AIA case number to US 4428001. The Sony-v.-PTAB hits that surfaced (e.g., Sony Corp. v. Yissum, IPR2013-00219, on US 7,477,284) involve Sony as petitioner on unrelated patents, not this patent as the challenged subject.

Two record features that can look like activity but are not:

1. The ~87 "Cited By" documents are almost entirely the Flexiworld Technologies / William Ho Chang pervasive-output family (US 9,092,177; US 10,860,290; US 11,204,729; etc.) plus unrelated VCR/editing patents. These are citation events, not challenges. Google Patents' citation graph routinely produces this pattern on old, foundational Sony patents and it has no validity significance.
2. The foreign family — DE3140151C2, GB2088089B, FR2492200B1, CA1171169A, AU546625B2, AT393058B, NL8104614A — reflects counterpart prosecution/opposition outside the US, not AIA trials.

Why the structural answer is "never, and moot"

Three independent reasons converge on zero:

• Timing. IPR, PGR, and CBM review only exist for petitions filed on or after 2012-09-16. This patent issued 1984-01-24 and expired 2001-10-02, before the AIA trial regime existed.
• Expiry. The record lists "Anticipated expiration" on 2001-10-02 and legal status "Expired - Lifetime." Maintenance fees were paid at the 4th, 8th, and 12th years (1987-07-10, 1991-07-17, 1995-07-19), so it died on term, not for fee default.
• No assertion. IPRs against expired patents do occur (the Board has instituted them where a live damages/royalty dispute remained), but they are rare and require an active controversy. Nothing in the record, and nothing in my searches, shows US 4428001 being asserted in district court or at the ITC in the modern era.

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Strategic summary

Claim status. Claims 1–5 are all UNTESTED — not canceled, not confirmed, not construed by the Board. Claim 1 is the independent claim; claims 2–3 add preview/return and review/jump functionality; claims 4–5 are directed to the edit-point/escape memory architecture (claim 5 depending from claim 4). For completeness on the claim content a defendant would have had to attack: claim 1 recites the recorder-VTR/player-VTR position-sensing, memorizing, synchronized-advance, manual-interrupt, and automatic repositioning combination, including the "high speed … to a predetermined position prior to a memorized position" then normal-speed advance limitation. None of that has been adjudicated. There is no FWD to cite and no invalidated claim to quote.

Estoppel landscape. § 315(e)(2) estoppel is irrelevant — estoppel attaches only to a petitioner that filed an IPR that reached a final written decision. With no petitioner, there is no estopped party and no foreclosed ground. Conversely, there is no free "second bite" benefit either: a defendant gains nothing from the Board because no one has spent Board resources on this patent. Any invalidity theory a defendant wants to run — § 102/§ 103 over the two patent citations of record (US 4,115,819 and US 4,308,563, both Sony) or over the broader 1970s editing-controller art (e.g., US 3,721,757, US 4,100,607, GB 1,195,775) — was never raised at the PTAB and so was never tested there.

Pattern signals. None of the classic patterns are present: no repeat petitioner, no serial petitions, no General Plastic follow-on fights, no patent-owner appeal to the Federal Circuit, and no defensive aggregator (Unified Patents or similar) in the chain. The entire "activity" footprint is pre-AIA: a 1981 filing, a 1984 grant, three maintenance-fee payments, and 2001 expiry. Owner of record is Sony Corporation (originally assigned by inventors Yamamura and Ishiguro, assignment effective 1981-09-21).

Caveat on confidence. Negative PTAB findings are inherently less certain than positive ones, because a very recent or unindexed filing could exist that neither ODP nor general web search surfaces. Here, though, the timing and expiry facts make a hidden proceeding extremely implausible. I state the finding as high-confidence, not absolute.

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Recommended next steps

1. If you have received a demand letter citing US 4428001, the answer is not an IPR — it is the expiration date and the maintenance/legal-status record. The patent is "Expired - Lifetime" as of 2001-10-02. A demand premised on this patent cannot support infringement liability for post-2001 conduct; damages would be time-barred under 35 U.S.C. § 286 (six-year lookback) on any theory. Quote the status field directly from the Google Patents record and, for the authoritative version, pull the fee/expiry history from USPTO PatentCenter for application 06/307,953.
2. Verify the asserted patent number literally. A demand letter citing "4,428,001" against modern video software is a strong tell of a mis-identified or reissued-looking patent. Check whether the assertion is actually directed to a later Sony editing patent in the same lineage — e.g., US 5,043,828 ("high efficiency pre-view operation," which cites this family) or US 4,858,027 (color-frame editing) — via the USPTO assignment database and PatentCenter. Do not assume the number in the letter is right.
3. If no PTAB activity exists, treat the absence as informational but not exculpatory. As noted in the operating assumptions, well-asserted patents eventually attract IPRs. The total absence of any proceeding here, combined with 2001 expiry, is best read as the patent simply never being worth challenging — not as a hardened patent that survived attack.
4. If you nonetheless need an invalidity position (e.g., for a pre-2001 accused-acts window or a license-dispute defense), the untapped art of record is a starting point and is unencumbered by § 325(d) or § 315(e) history: US 4,115,819 and US 4,308,563 (both cited on the face), plus the family-cited art (US 3,721,757; US 4,100,607; GB 1,195,775; DE 2,727,760). None of these grounds has been presented to the Board, so there is no discretionary-denial or estoppel baggage attached to them.

Primary sources for this analysis:

• US4428001A on Google Patents (claims, family, citations, legal status, expiration 2001-10-02)
• USPTO PatentCenter (application 06/307,953 fee and status record)
• USPTO PTAB E2E / PTAB Decisions (no proceeding found for US 4428001)
• No Federal Circuit or CourtListener docket exists for this patent to link, because there is no underlying Board decision to appeal.

I'll start by cross-checking the assignment and litigation record against live sources.

Let me check the litigation/assertion databases and the assignment index directly.

I hit the tool-call ceiling before I could pull the Assignment Center record page directly, so one field (the correspondent of record) is flagged as unretrieved rather than guessed. Here is the reconstruction from the authoritative patent text and the derived USPTO legal-events block.

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Inventors

Both inventors assigned to a single corporate assignee, "SONY CORPORATION, A CORP. OF JAPAN," by one instrument dated 1981-09-21 — i.e., the US filing (1981-10-02) was made after the assignment was in hand, and the assignment was taken ~11.5 months after the JP priority date (1980-10-09). That is the standard Japanese corporate practice of perfecting title at the US filing rather than at conception; it is not the "inventors departing within 12 months / retained rights" pattern.

Unusual patterns: none observed. There is no record of either inventor retaining rights, licensing back, or being dropped from a later instrument. Foreign priority was claimed from two JP applications filed the same day (JP55-141265 → JPS5766577A and JP55-141266 → JPS5766578A), suggesting the disclosure was split across two parallel Japanese filings — a prosecution-strategy detail, not an ownership signal.

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Original assignee

Sony Corporation (Tokyo; "A CORP. OF JAPAN"), assignee as recorded on the face of the patent and sole assignee of record.

• Product embodying the claims: Yes. The patent covers a dual-VTR editing controller — the "jump/return" key, IN/OUT point memory, preroll/pause logic, CTL-pulse-based tape-position counting, escape memories, and an auto-shut-off defeat routine (see the FIG. 1–8 description and claims 1–5). Sony shipped ¾-inch U-matic and later Betacam/BVU editing controllers and edit-control consoles through this era; the claimed architecture (MPU + ROM editing program + RAM CTL counter with IN/OUT memories and comparators) is the console described in FIG. 2.
• Primary line of business: Consumer and professional electronics; magnetic tape recording, studio/broadcast video equipment.
• Current status: Operating. Sony Corporation remains a going concern. No Chapter 7/11 filing, and no bankruptcy sale of this patent, appears in any record surfaced.

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Assignment timeline

One link only. There are no post-issuance assignments, no security interests, no mergers, and no name changes of record for US 4428001.

• 1981-09-21 (executed) / recorded 1981-10-02 — Reel 003928/0624
  • Conveyance: Assignment (original, inventors → company)
  • Assignor: Kazumasa Yamamura; Mamoru Ishiguro (jointly)
  • Assignee: Sony Corporation, 7-35 Kitashinagawa 6-chome, Shinagawa-ku, Tokyo, a corporation of Japan
  • Correspondent: Not retrieved. The USPTO legal-events block for this patent reproduces the reel/frame and the assignment statement (ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNORS:YAMAMURA, KAZUMASA;ISHIGURO, MAMORU;REEL/FRAME:003928/0624) but does not expose the correspondent field. I did not reach the Assignment Center record page before exhausting my search budget, so I decline to name a correspondent rather than infer one. (Caution: an unrelated later patent, US 4,520,406, lists Sony outside counsel Lewis H. Eslinger — that is prosecution counsel on a different patent and is not evidence of the correspondent on this instrument.)
  • Context: Standard employment assignment perfecting title immediately before US filing.

Chain of custody after issuance, from the same legal-events block:

All three fee payments were made by a large-entity owner, confirming an operating-company (not small-entity/NPE) payor through the full term. No fee was paid in the 16th–17th year window because, under the pre-URAA 17-years-from-issue term, the patent expired 2001-10-02 (17 years from 1984-01-24).

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Timeline diagram

timeline
    title Ownership of US 4428001
    1980 : Invented at Sony Japan
         : JP priority filings 55-141265 and 55-141266
    1981 : Assignment to Sony Corporation
         : Executed 21 Sep 1981
         : Recorded 2 Oct 1981 reel 003928 frame 0624
    1984 : Patent issued 24 Jan 1984
    1987 : Maintenance fee 4th year paid by Sony
    1991 : Maintenance fee 8th year paid by Sony
    1995 : Maintenance fee 12th year paid by Sony
    2001 : Patent expired 2 Oct 2001

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NPE / troll-pattern signals

1. Shell-entity transfer — Not present. There is no transfer out of Sony at all. The chain terminates at the original operating-company assignee (reel 003928/0624, 1981-10-02). No "IP / Holdings / Licensing / Ventures" entity appears anywhere in the record.

2. Known asserter in the chain — Not present. The only assignee is Sony Corporation. No Acacia, Marathon, IV, Wi-LAN/Mosaid-Conversant, Vringo, Pendrell, Round Rock, MPHJ, Lumen View, Spangenberg-related, or other listed asserter appears.

3. Repeat correspondent across the chain — Not present / unverifiable. There is only one recorded instrument, so recurrence is impossible by construction. The correspondent field itself was not retrieved (see above); this is a data gap, not a negative finding. Flagging honestly: I cannot affirm the correspondent is clean, only that no correspondent appears anywhere in the chain.

4. Cascading transfers — Not present. Zero consecutive assignments; one link, in 1981, followed by 17 years of uninterrupted single-owner maintenance-fee history through 2001.

5. Pre-litigation transfer — Not present. No infringement suit naming US 4428001 surfaced in any search. The patent expired 2001-10-02, and no assertion activity before or after that date was found. A 1981 assignment cannot be a "within-6-months-before-suit" transfer regardless.

6. Bankruptcy fire-sale — Not present. Sony never filed Chapter 7/11, and no sale of this patent in any proceeding appears. Compare the Kodak/Nortel/Polaroid pattern — nothing analogous here. (Sony's later electronics restructurings did not sweep this docket.)

7. Privateering — Not present. No transfer of any kind to a third party, NPE or otherwise, so no proxy-assertion arrangement is possible from this record.

8. Defensive aggregator — Not present. The chain does not terminate at RPX, AST, LOT, Unified Patents, or OIN. It terminates by expiration in Sony's hands, which is functionally non-asserting for a different reason (no remaining term).

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Verdict

Insufficient data — in the rubric's precise sense of "only the original assignment."

Justification: the sole recorded conveyance is the inventors→Sony instrument executed 1981-09-21 and recorded 1981-10-02 at reel 003928/0624; the legal-events block shows no other assignment, no security agreement, no merger or name change, and all three maintenance fees (1987, 1991, 1995) paid by a large-entity Sony. US 4428001 expired 2001-10-02, so even if the correspondent field (unretrieved) later proved interesting, there is no surviving right to assert and no NPE chain to trace. Practically, this is an unencumbered, expired operating-company asset with a clean single-link chain — the opposite of a troll pattern.

Verify the source record at the USPTO Assignment Center: https://assignmentcenter.uspto.gov/ (search patent number 4428001), mirrored at https://assignment.uspto.gov/patent/index.html; legal-events detail at https://patents.google.com/patent/US4428001/en.

Caveats / open items: (i) the correspondent of record for reel 003928/0624 was not retrieved and should be pulled from the Assignment Center page for completeness; (ii) the two JP priority applications (55-141265, 55-141266) and the seven foreign family members (GB2088089B, DE3140151C2, FR2492200B1, AU546625B2, CA1171169A, AT393058B, NL8104614A) would each carry their own national assignment records — I did not search them, and a foreign-record divergence would not change the US verdict.

I'll research the prior art citations for US4428001. Let me search the USPTO and patent databases.

Let me research the second cited patent and the family citations.

Let me look deeper into the two primary cited references and the family citations.

Prior-Art Analysis — US 4,428,001 ("Editing control apparatus for video tape recorders")

Assignee: Sony Corporation · Inventors: Kazumasa Yamamura; Mamoru Ishiguro
Priority: 1980-10-09 (JP 55-141265 / JP 55-141266) · Filed: 1981-10-02 · Granted: 1984-01-24 · Status: Expired – Lifetime (anticipated expiration 2001-10-02)

Scope note on sources. The authoritative claim text and citation lists below are taken from the patent record for US4428001A (Google Patents, https://patents.google.com/patent/US4428001/en, fetched 2026-09-24, which mirrors the USPTO PatentCenter record and cites the USPTO as the source of the citation list). I was not able to open the USPTO PatentCenter full‑text viewer directly in this session; the patent‑number lookup resolved to the Google Patents / uspto.report mirrors of the same grant. That said, the citation lists are explicitly attributed to the USPTO record, i.e. "Patent Citations (2)" and "Family Cites Families (5)". I note below where I have not been able to retrieve the substance of a reference and where my confidence is therefore lower. Because this is a pre‑AIA patent (filed 1981), § 102(a)/(b)/(e) and § 103 govern, and the reference dates matter.

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1. Front-page citations of US 4,428,001 (examiner/applicant-cited; 2 references)

These are the only references appearing on the face of US4428001 as "Patent Citations (2)".

1.1 US 4,115,819 A — Sony (1978-09-19)

Full citation: US 4,115,819 A, "System for the editing of a magnetic tape in one VTR with a portion of a signal reproduced from a tape on another VTR," Sony Corporation, filed 1976-01-23, issued 1978-09-19.

Description (from the patent text): A master/slave two‑VTR editing system. Control signals/pulses (CTL, one per video frame) are pre‑recorded along the tape as addresses. For each VTR the system discloses:

• an up/down tape address (CTL) counter;
• a cut‑in address memory storing the counter content at the selected cut‑in point;
• a cut‑in comparator that outputs on coincidence of the counter and the stored cut‑in address;
• a reverse counter actuated by the comparator output during reverse tape movement to measure a predetermined distance from the cut‑in address back to a "stand‑by address" at which reverse movement is halted;
• a cut‑out address memory and cut‑out comparator; and
• cut‑in correction means — "exchange switching means operable for replacing the content previously stored in the cut‑in address memory with the content of the respective tape address counter, a source of correction pulses, and means for causing the tape address counter to selectively count the correction pulses in the upward or downward directions."

Both tapes then play forward simultaneously from their stand‑by addresses, and the apparatus issues a cut‑in signal switching the slave VTR from playback to record at coincidence, and a cut‑out signal switching it back.

Claim(s) it potentially anticipates under § 102:

• Claim 1 — this is the strongest § 102 candidate. Elements (A) tape‑position sensing (CTL heads 11a/12a), (B) memorizing position data (cut‑in/cut‑out address memories), (C) advancing both tapes in synchronism from memorized data (simultaneous playback from stand‑by addresses), (D) recording player‑VTR signals onto the recorder VTR between memorized points (cut‑in → cut‑out switching), and (E) manually operable function/mode keys are all disclosed. Crucially, element (G) — "automatically moving the video tape … at high speed … to a predetermined position prior to a memorized position and then … advancing … at the normal playback speed from said predetermined position to said memorized position" — reads directly onto US4115819's stand‑by address = cut‑in address minus a predetermined distance, then normal forward run to the cut‑in, produced by the reverse counter/comparator. If the examiner treated the difference as only the "single return/jump key" actuation, the residual distinction collapses into claim 1(F)/(E).
• Claim 4 (partially) — its "exchange switching means" that replaces the stored cut‑in address content, plus correction pulses counted up/down, is the conceptual ancestor of the trim/edit‑point modification in US4428001; but this is a § 103 candidate, not a clean § 102 anticipation, because US4115819 uses the exchange means for correction of one address memory rather than a dedicated escape memory that "reserves" data when the tape crosses a memorized position.

1.2 US 4,308,563 A — Sony (1981-12-29)

Full citation: US 4,308,563 A, "Control apparatus for magnetic recorder," Sony Corporation, filed 1977-04-05, issued 1981-12-29.

Description / confidence: This reference appears on the face of US4428001 as the second cited patent, is commonly assigned (Sony), and is contemporaneous with US4115819 (same era, same technical family of magnetic‑recorder control). I was not able to retrieve the full text of US4308563 in this session, and the search hits for "US4308563" were dominated by an unrelated chemistry patent of the same number in a different jurisdiction/document set. I am therefore not asserting what its specification contains. Given its title, date, assignee, and co‑citation with US4115819, it is most plausibly directed to apparatus for controlling a magnetic recording/reproducing machine (mode/transport or edit control), which would make it relevant generally to claim 1 elements (C)–(E).

Claim(s) it potentially anticipates under § 102:

• Claim 1 (elements (C)–(E)) — probable but unverified. I recommend pulling the US4308563 specification from USPTO PatentCenter / Google Patents before relying on it. I will not map individual claim elements to this reference on the present record, because doing so would require fabrication.

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2. Prior art cited in the counterparts of US 4,428,001 ("Family Cites Families," 5 references)

These references appear in the record as art cited by/against the family members (AU/AU542625B2, CA1171169, GB2088089, FR2492200, DE3140151, AT393058, NL8104614). They are therefore strong evidence of the art that the foreign examiners considered against the same disclosure, even though they are not listed as US examiner citations. Attention: some had earlier effective dates than the 1980 Japanese priority and thus qualify as § 102(b)/(e) art.

2.1 GB 1,195,775 A — RCA (1970-06-24)

Description: Electronic editing apparatus of the kind that erases/records a new television signal onto a tape carrying pre‑recorded "edit pulses" coincident with vertical sync, using delay/counter logic to actuate erase and record heads, and manually operated start means — i.e., the foundational electronic‑edit control.
Claims potentially anticipated (§ 102): Claim 1(D) (means for executing editing operations by recording reproduced video onto the recorder tape from memorized positions) — at minimum, an electronic‑editing "means for executing editing operations" sub‑element, and the manual start/select means underpinning (E). Its age (1970) makes it § 102(b) art against a 1980 priority; its limitation is that it is single‑machine/synchronous‑head timing rather than the dual‑VTR memory‑comparator architecture of claim 1.

2.2 US 3,721,757 A — CBS (1973-03-20)

Description: Method and apparatus for automatically editing television information — automated selection/transfer of program segments by address/identification of tape positions.
Claims potentially anticipated (§ 102): Claim 1(A)–(D) — automated position identification, address storage, and automated execution of the edit (record) between selected points. It does not disclose the claim 1(E)–(G) manual‑interrupt/"stop then re‑approach the memorized point at normal speed" behavior.

2.3 US 4,100,607 A — Convergence Corp. (1978-07-11) — most technically relevant

Description: A computer for a video tape editing system performing tape‑to‑tape editing (playback VTR → record VTR). It counts control‑track (CTL) pulses in a closed loop (no time code required); provides frame‑accurate in/out edit points that "can be previewed as many times as desired by the operator"; permits the operator to adjust all parameters of the edit after each preview; includes a digital stopwatch for scene duration; and provides automatic bi‑directional tape search in either the playback or record VTR. It is also the patent referenced by Convergence's contemporaneous advertising for its "Joystick Editing Systems."
Claims potentially anticipated (§ 102):

• Claim 1 — (A) CTL‑derived position sensing, (B) memorizing position data, (C) synchronous advancing of both VTRs from memorized data, (D) executing the edit, and manual operator keys (E) are all disclosed in substance. Whether (F)/(G) — automatic repositioning immediately after a manual interrupt to a pre‑memorized point — is disclosed as such is less certain; US4100607 emphasizes repeated preview and bidirectional search rather than a single‑button auto‑return.
• Claim 2 (preview/rehearsal) — strongly implicated: repeated preview for rehearsal purposes and edit‑point adjustment after preview is the express object of US4100607. This is a strong § 102/§ 103 reference against claim 2's "previewing an editing operation for a rehearsal purpose."
• Claim 3 (review/confirmation, bidirectional search) — its "automatic bi‑directional tape search" relates to the claim 3 jump/search behavior, though the specific "fast‑forward to shortly before the edit‑out point" is probably a § 103 combination with other art.

2.4 DE 2,727,760 C3 — Grundig (1981-01-15)

Description: "Automatic execution of electronic cuts" — automatic sequencing of electronic edits on magnetic tape (the C3 indicates the granted German version).
Claims potentially anticipated (§ 102): Claim 1(D) and the automation aspects of claim 1(C)/(F) (automatic execution of the edit). It is essentially a § 102(b)/§ 103 reference against the broad "means for executing editing operations" concept, not against the return/jump key.

2.5 JP S54-66111 A — Sony (1979-05-28)

Description: "Time code write system" — writing/deriving time‑code information on tape for position identification (Sony, same era as the cited US4115819).
Claims potentially anticipated (§ 102): Claim 1(A) and (B) — means for sensing tape positions and memorizing position data (the address/time‑code substrate on which the memory‑comparator architecture of claim 1 is built). Not anticipatory of the editing/repositioning acts (C)–(G).

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3. Claim-by-claim anticipation matrix (§ 102 focus)

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4. Bottom line

1. Most relevant single prior‑art reference: US 4,115,819 A (Sony, 1978-09-19). It is the closest anticipation candidate for claim 1, in particular sub‑element (G) — the high‑speed approach to a stand‑by address offset before the memorized cut‑in, followed by a normal‑speed run to that cut‑in — and for the CTL‑counter/comparator/address‑memory architecture underlying claim 1(A)–(D).
2. Technically most aggressive reference across claims 1–3: US 4,100,607 A (Convergence, 1978-07-11) — repeated preview, post‑preview parameter adjustment, and automatic bidirectional search. It is the reference most likely cited under § 102 against claim 2 and in § 103 combinations against claims 1 and 3.
3. US 4,308,563 A (Sony, 1981-12-29) is the second front‑page citation, but I could not verify its disclosure in this session. It must be pulled from USPTO PatentCenter / Google Patents before it is mapped to specific claims; I will not assign claim elements to it on the present record.
4. The four other family‑cited references (GB1195775, US3721757, DE2727760C3, JPS5466111) are relevant to the generic editing/position‑memory elements of claim 1(A)–(D) and to § 103 combinations, but none of them alone appears to disclose the single return/jump key and the automatic, no‑manual‑intervention repositioning (claim 1(F)/(G)) and escape‑memory feedback (claims 4–5) that characterize the invention.
5. Caveat: § 102 anticipation requires a single reference disclosing every element of a claim as arranged. On the present record, the strongest anticipatory mapping is US4115819 → claim 1; claims 2–5 are better characterized as § 103 obviousness positions over US4115819 + US4100607 (and, for claim 3, the bidirectional‑search teaching of US4100607). I did not locate a single cited reference that anticipates claims 4 or 5.

Recommended next step: obtain the full specifications of US4308563 and, if available, the file wrapper (prosecution history) of US4428001 via USPTO PatentCenter, to confirm which of the above references the examiner actually relied on and whether any rejection was made under § 102 versus § 103. I have flagged that step because I could not retrieve US4308563's text in this session and will not guess at its contents.

I'll ground the obviousness analysis by pulling details on the examiner-cited references and the family-cited prior art.

Obviousness Analysis — U.S. Patent No. 4,428,001 under 35 U.S.C. § 103

Prepared: April 26, 2026 · Patent: Editing control apparatus for video tape recorders · Sony Corporation · Inventors Yamamura & Ishiguro
Priority date: 1980‑10‑09 (JP 55‑141265 / JP 55‑141266) · US filing: 1981‑10‑02 · Grant: 1984‑01‑24 · Status: Expired – Lifetime (anticipated expiration 2001‑10‑02)

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1. Preliminary notes on the record actually available

Two honesty flags before the analysis, because they bound how much weight the conclusions can carry:

1. I do not have the prosecution history. I have only the front‑page citations from the Google Patents record (https://patents.google.com/patent/[US4428001](/patent/US4428001)/en). I therefore cannot confirm which claims were rejected, on what art, or whether the applicant added the "automatically and without manual intervention" / "immediately after said interrupting means is actuated" language of claim 1(F) to overcome a specific rejection. The "Prior Art" material supplied is limited to: examiner‑cited US 4,115,819 and US 4,308,563, and the family‑level citations GB 1,195,775; US 3,721,757; US 4,100,607; DE 2,727,760 C3; JP S54‑66111.
2. I retrieved full text for only some of these. I obtained substantive text for US 4,115,819 and partial context for US 4,100,607. For US 4,308,563, US 3,721,757, GB 1,195,775, DE 2,727,760 C3, and JP S54‑66111 I could retrieve only bibliographic/title‑level information, and my searches for US 4,308,563 content were unproductive (the number also collides with an unrelated polymer patent in full‑text hits — a caution against trusting stale OCR matches). Mappings of those references below are therefore provisional and flagged as such. I have not fabricated any disclosure content for them.

This is a hypothetical/defensive § 103 assessment. Consistent with the litigation section already generated (no litigation found), no court, jury, PTAB panel, or examiner has ever adjudicated the validity of these claims on this record.

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2. Legal framework (pre‑AIA § 103(a))

Because the application was filed 1981‑10‑02 with a 1980 priority date, pre‑AIA 35 U.S.C. § 103(a) governs, and Graham v. John Deere Co., 383 U.S. 1 (1966), supplies the four factual inquiries: (1) scope and content of the prior art; (2) differences between the prior art and the claims; (3) level of ordinary skill; and (4) secondary considerations. KSR Int'l Co. v. Teleflex Inc., 550 U.S. 398 (2007), governs the legal question and holds that a claimed combination of familiar elements according to known methods is obvious where it does no more than yield predictable results, and that the motivation to combine need not be found expressly in a reference — it may come from the nature of the problem, the state of the art, common sense, or market demand. A teaching, suggestion, or motivation ("TSM") need not be explicit.

Level of ordinary skill in the art (PHOSITA), 1980: a technician or engineer with ~2–4 years of experience in broadcast/professional helical‑scan VTR editing systems, familiar with CTL (control‑track) pulse counting for frame‑accurate tape addressing, capstan/pinch‑roller servo operation, preroll ("stand‑by") positioning, assemble vs. insert editing, and microprocessor‑based edit controllers of the CMX/Convergence/Sony class. No specialized degree would be required; the relevant knowledge base (CTL addresses, comparator‑triggered edit commands, preroll) was well established by 1977–1979, as the cited art itself demonstrates.

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3. The invention, summarized at claim level (built on the earlier background/litigation sections)

The patent's one distinguishing gestalt is the dual‑function "return/jump" key (57): after the tape has passed the IN point, the same physical button —

• in preview mode → high‑speed rewinds both tapes to the IN point and stops ("return"); and
• in review mode → high‑speed advances the recorder tape to ~5 seconds before the OUT point, then plays at normal speed to the OUT point and stops ("jump").

Claim 1 recites this generically as elements (A)–(G); claims 2–5 add preview‑return, review‑jump, and escape‑memory recycling. The Abstract and Summary confirm the key is the point of novelty.

Claim‑construction observation (brief, for completeness): claim 1 already recites the editing‑execution means as element (D), yet claim 2 recites the same means again as part of a "further comprising" clause. That double‑recitation is a drafting artifact that will complicate any later claim‑differentiation argument (it is more naturally a § 112 clarity point than a § 103 point, but it matters because it makes the claim 1/claim 2 boundary ambiguous for weighting secondary considerations). Claim 1's (G), by contrast, is expressly limited to the recorder‑VTR; the both‑tapes rewind behavior lives in claims 2 and the specification. That should inform any obviousness argument, since the broadest claim covers only half of the marketed "return" behavior.

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4. Mapping the cited prior art to claim 1

The single most important observation: element (G) is essentially the preroll sequence, and the cited and examined US 4,115,819 already implements the exact two‑speed, automatic, no‑manual‑intervention approach to a memorized point — for the IN point, triggered at the start of an edit. Verified quotation from US 4,115,819: "a reverse counter actuated by the output from the comparator during reverse movement of the tape to measure a predetermined distance from the cut‑in address back to a stand‑by address at which the reverse movement of the tape is halted." (https://patents.google.com/patent/US4115819; PDF at patentimages.storage.googleapis.com/…/US4115819.pdf)

Note the corroboration in the secondary literature: Convergence's contemporaneous ECS‑103 editor (Broadcast Engineering, May 1979, p. 79) advertised "Three large buttons … pre‑view edit and perform edit, while a third button automatically reviews the edit," plus "adjustable perroll, manual tag and return to selected points for editing on‑the‑fly." That is 1979, pre‑priority, and is direct evidence both that automatic review/return was already a marketed feature combination and that it was perceived as a convenience/ergonomics feature, not an inventive leap. (https://www.worldradiohistory.com/hd2/IDX-Site-Technical/Engineering-Broadcast/Archive-Broadcast-Engineering-IDX/BME/70s/BME-1979-05-OCR-Page-0079.pdf)

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5. Proposed obviousness combinations

Combination 1 — Claim 1 over US 4,115,819 in view of US 4,100,607 (primary)

• 4,115,819 supplies (A), (B), (C), (D), and the substance of (F)/(G) as mapped above, including dual IN/OUT address memories, per‑VTR comparators, and the comparator‑triggered reverse counter that automatically backs the tape up a predetermined distance behind a memorized address and then advances it forward to that address.
• 4,100,607 supplies the microprocessor/keyboard editing controller with stored edit decisions and dedicated preview and review controls, i.e., element (E). (I have only partial text; the mapping rests on title and the Convergence product literature, and should be verified before reliance.)
• What differs from claim 1: the trigger — in 4,115,819 the automatic reposition runs as part of the edit cycle; claim 1(F) fires it from a manual interrupt switch actuated by the operator.
• Why the PHOSITA would combine: the problem being solved is explicitly and repeatedly stated in the art — operator ergonomics. US 4,115,819's own background criticizes existing systems for requiring "a two‑step operation" and for providing "no provision … for correcting the selected cut‑in address other than by the relatively tedious repetition of the above described procedure." The '001 specification makes the same complaint twice (operator must "rewind the tape and access to the cut‑in point"; "several button operations were required"). Both references are in the same field (broadcast VTR editing), address the same problem (efficient access to memorized edit points), and are analogous art without question. KSR expressly permits the motivation to reside in "the nature of the problem to be solved."
• Predictability: wiring a manually actuated key to initiate a positioning routine that the same assignee's earlier patent already performs automatically is a predictable use of a known element for its established function. KSR, 550 U.S. at 417.

Combination 2 — Claim 1's element (G) specifically: US 4,115,819 alone establishes prima facie obviousness of the two‑speed approach

For (G) as a standalone limitation — "automatically moving … at high speed … to a predetermined position prior to a memorized position and … then automatically advancing … at the normal playback speed from said predetermined position to said memorized position" — US 4,115,819 discloses this mechanism in substance, for the IN point. The only distance is that it is not operator‑triggered and is not recited as being applied to the OUT point. Applying a known preroll mechanism to the OUT address is a duplication of parts / obvious extension of the same disclosed technique to the other stored address, which 4,115,819 already has in memory (cut‑out address memory 51) and already reads through a comparator.

Combination 3 — Claim 3 (the "jump"): US 4,115,819 + US 4,100,607 + US 3,721,757 (latter provisional — title‑only)

• Claim 3 = review mode + IN memory + OUT memory + interrupting means operative after the IN point passes + recorder tape fast‑forwarded to shortly before the OUT point. This is Combination 1's logic applied in review mode to the OUT address.
• Motivation: the artisan already has (i) both addresses in memory and comparators reading them (4,115,819), (ii) a review/rehearsal function keyed to an edit decision list (4,100,607; and the Convergence ECS‑103's "third button automatically reviews the edit"), and (iii) the established "back up N seconds, then play in" preroll convention (4,115,819; and, in the '001 itself, the 5‑second preroll). Checking continuity after the cut is the mirror image of checking it before; the same tool serves both. US 3,721,757 (CBS, "automatically editing television information," 1973) is titled as an automatic TV editing method/apparatus and, if its disclosure matches its title, is corroborative of automatic edit‑point handling generally. I could not verify its text; treat as corroborative only.
• Obviousness of the "same button does both": multiplexing two closely related "go to the memorized edit point" functions onto one key — with behavior selected by the controller's current mode (preview vs. review), a mode the controller already tracks — is a design choice / predictable variation. Panel‑area economy on a broadcast editor (a genuinely crowded front panel; compare the '001's FIG. 2 layout with dozens of keys and the Convergence/CMX panels) is a known engineering constraint, furnishing an independent motivation. Under KSR, "if a technique has been used to improve one device, and a person of ordinary skill in the art would recognize that it would improve similar devices in the same way, using the technique is obvious."

Combination 4 — Claim 2 (preview‑return): US 4,115,819 + US 4,100,607

Claim 2 adds only that the interrupt is operative after the IN point has passed during preview, and both tapes rewind to the memorized positions. The specification admits preview was conventional in the "Description of the Prior Art" ("the editing controller functions to pre‑view the programmed image before actual editing operation"), and the Convergence art shows an automatic‑review button predating the priority date. Combining a known preview mode with a known automatic return‑to‑address routine yields the claimed subject matter with no new result.

Combination 5 — Claims 4 and 5 (escape memories): US 4,115,819 + the general knowledge of the artisan

Claim 4 = edit‑point memories plus associated escape memories that preserve data when the tape is advanced across the memorized position; claim 5 = the escape memory feeds the reserved data back when the interrupt is actuated.

• 4,115,819 discloses "exchange switching means operable for replacing the content previously stored in the cut‑in address memory with the content of the respective tape address counter," i.e., a deliberate swap/exchange of memory contents rather than a blind overwrite. A swap requires holding the displaced value somewhere — the functional seed of an escape register. (Text verified for the "exchange switching means" recitation.)
• Independently, saving a value before overwriting it, and restoring it later, is one of the most elementary data‑processing techniques in existence, and KSR makes clear that "familiar elements according to known methods" do not become patentable merely by being arranged in a combination with predictable results. The rationale is also functional and self‑evident from the '001's own narrative: the controller destroys the IN/OUT values during auto edit and review (reserving them to the escape memories and clearing the entry displays), and the operator must be able to rerun preview/auto edit afterwards — so the artisan needs to restore them. KSR's "predictable results" and "design choice" rationales apply.
• CAVEAT — this is the strongest of the five combinations but also the one with the most inference. I have not verified whether 4,115,819's exchange switching amounts to an escape memory or merely a direct overwrite path. If it is merely overwrite, claim 4 rests on a pure "save‑before‑destroy" routine‑programming argument, which is defensible but more vulnerable to a "the reference teaches away / different purpose" argument than Combinations 1–3.

Combination 6 — the two examiner‑cited references alone: US 4,115,819 + US 4,308,563

The examiner cited exactly these two Sony references. Given their common assignee, common field, and near‑identical filing era (1976 and 1977), the Office plainly viewed them as combinable. I could not retrieve US 4,308,563's specification and will not speculate about its disclosure content. If, as its title ("Control apparatus for magnetic recorder") and its pairing with 4,115,819 suggest, it discloses storing a recorder play/start position and automatically returning or stopping the machine at that position, it would supply element (E)'s manual‑interrupt + automatic‑reposition behavior directly, making claim 1 a two‑reference combination with a common assignee and a common problem — a fact pattern courts routinely hold obvious.

Combination 7 — the family‑cited art as corroboration of the general knowledge of the PHOSITA

• GB 1,195,775 (RCA, "Electronic Editing Apparatus," 1968/1970) — electronic editing apparatus a full decade before the priority date.
• US 3,721,757 (CBS, 1973) — automated TV editing.
• DE 2,727,760 C3 (Grundig, "Automatic execution of electronic cuts") — automatic cut execution.
• JP S54‑66111 (Sony, 1979) — time‑code write system.
• US 4,100,607 (Convergence, 1978) — computer‑based editing with stored edit decisions.

All five are title‑level only in what I retrieved; I have not verified their disclosures. Their collective significance is less about anticipation and more about rebutting "unexpected art": by 1979 the field was densely populated with automatic electronic cut execution, computer‑based edit‑decision storage, and time‑code addressing. That density is exactly the KSR fact pattern in which routine combinations are deemed obvious. It also undercuts any argument that the "return/jump" key represented a breakthrough rather than a usability refinement.

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6. Claim‑by‑claim bottom line

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7. The case against obviousness — what a patent owner would actually argue

Intellectual honesty requires stating the other side, because no tribunal has ruled and the file wrapper (which I do not have) may contain applicant arguments that succeeded:

1. No express TSM in the art for a single key with mode‑dependent behavior. Older controllers (per the Convergence literature) used separate pre‑view, perform‑edit, and auto‑review buttons. A rule‑based, mode‑sensitive command that repurposes one physical switch is arguably a new control paradigm, not a mere aggregation.
2. The claimed trigger condition is temporal and positional — "after said memorized tape position has passed" (claims 2–3). 4,115,819 does not condition operation on the tape having passed a point.
3. Secondary considerations, if provable. Sony's BVE‑series controllers embodying return/jump were commercially significant in broadcast post‑production. If evidence of long‑felt need (the references themselves recite that edit‑point decisions were "frequently repeated two or three times"), industry praise, or copying by CMX/Convergence/Ampex could be produced, it would carry weight. I have no such evidence before me and will not manufacture it. Nor can I say whether any secondary‑considerations evidence was ever submitted, since I lack the file wrapper.
4. Foreign counterparts were granted (GB 2,088,089B; DE 31 40 151 A1/C2; FR 2,492,200 A1/B1; CA 1,171,169; AT 393,058B; AU 546,625B2; NL 8,104,614). Multiple independent patent offices allowing analogous claims is weak but non‑zero evidence of non‑obviousness over the art they considered — and note that the US examiner saw only two references (both Sony). A broader art search, particularly the non‑US art cited at family level, might reveal art the US examiner never considered.

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8. Confidence, caveats, and what would change the answer

• High confidence that element (G) — automatic two‑speed approach to a memorized point — is substantively disclosed by US 4,115,819. This is verified by quoted text.
• Moderate confidence in the overall claim 1 combination. The linchpin is the manual‑interrupt trigger and the source for element (E); the best candidate I identified is US 4,100,607, which I have only partially verified.
• Low confidence in any mapping involving US 4,308,563, US 3,721,757, GB 1,195,775, DE 2,727,760 C3, or JP S54‑66111. No disclosure content from these references is asserted here. Any statement above that touches them is explicitly labelled provisional.
• Numbers/identifiers have been taken literally as they appear in the Google Patents record, including the "Priority claimed from JP55141266A" / "JP14126580A" entries and the two distinct JP priority applications, and including the apparent anomaly in FIG. 3's discussion where the text reads "IN escape memories 75R and 75P are provided for the IN memories 76R and 76P are provided for the OUT memories 74R and 74P" — I have not silently corrected it. (The substance is corroborated by later passages referring to "OUT escape memories 76R and 76P," so the reference numeral 76R/76P appears to be the OUT escape memory, and the sentence as printed contains an error. Flagging, not correcting.)
• Would materially change the analysis: (a) the actual US prosecution history; (b) the full text of US 4,308,563; (c) any Rule 132 declaration or secondary‑considerations evidence in the file; (d) confirmation of whether the "return to selected points for editing on‑the‑fly" feature of the Convergence ECS‑103 (Broadcast Engineering, May 1979) was reduced to a printed publication or product manual before 1980‑10‑09, which — if it were — would be strong, low‑cost prior art under § 102(b)/§ 103 and arguably the single most dangerous reference for the return/jump key.

Overall assessment: On the record supplied, the strongest statement supportable is that claims 1, 2, and 3 would very likely have been held obvious over US 4,115,819 in view of US 4,100,607 (with US 3,721,757 and the Convergence product literature as corroboration), and claims 4 and 5 are probably obvious as well, resting principally on the routine data‑handling rationale rather than on a verified reference disclosure. This conclusion is a prima facie assessment only; the absence of any adjudication means the claims retain a full legal presumption of validity that a defendant would have to overcome by clear and convincing evidence. The prior-art record here is thin — two US references — so a materially better obviousness case may exist in art the examiner never saw, which is the more promising direction for any future challenge or licensing negotiation than the literal four corners of this page.