US 2750498

I'll run targeted searches to confirm the details and check for any litigation/docket activity.

Let me check for any litigation or CAFC docket activity referencing this patent.

US Patent 2,750,498 — Summary

Verification: The identifiers resolve to a single US patent. I did not find any CAFC 2026 docket entry, District Court complaint, or PTAB proceeding referencing this patent. I also found several unrelated documents bearing the string "2750498" (a Canadian patent 2,750,498 for an intra‑operative blood‑recovery system, Japanese Patent No. 2750498 for a wood‑moisture meter, EP2750498A1 "Snap trap," ES2750498T3, RU2750498C2, a Brazilian STJ case number, a Florida FEI number, and DOT# 2750498) — none of these are US Patent 2,750,498 and should not be conflated with it.

Bibliographic data (from the authoritative full text)

Abstract

Uncertainty flag: This patent, filed in July 1952, predates the modern rule requiring a formal "Abstract of the Disclosure." No standalone abstract appears in the patent text; the description opens directly with "This invention relates to the synchronization of electron beam deflection apparatus…" The following is a faithful condensation of the stated objects and summary of the invention, as derived from the specification (the Google Patents page reproduces this as its "Definitions" section rather than as an original abstract):

Synchronizing signals are impressed on the frequency-control circuit of a sweep-control oscillator only during fractions of the deflection cycle while the system is in sync. A gate (gated sync-signal amplifier) normally blocks the sync pulses and is briefly opened by pulses clipped from the peak of the locally generated sawtooth wave. During asynchronous periods, a coincidence detector (comparing incoming sync pulses with locally derived indicating pulses) lowers the gate threshold so the gate conducts sync signals continuously, and simultaneously raises the clipper level so that no gate-operating pulses are produced. This provides high immunity to random noise pulses while permitting fast initial synchronization and rapid resynchronization, because long-time-constant AFC circuits are avoided.

Plain-language overview of the independent claims

The patent has 13 independent claims (1, 2, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16) and 3 dependent claims (3, 4, 5, all depending from claim 2).

Claim 1 — Basic gated/noise-immune sync architecture. A deflection-wave generator contains an oscillator with a frequency-control circuit. A source of periodic sync pulses feeds a gating apparatus whose output goes to the oscillator's frequency-control circuit. The gate is normally conditioned during synchronous operation for non-conduction, so that it can be momentarily rendered operative to pass sync pulses. A second means, active during asynchronous operation, changes the conditioning so the gate is continuously conductive. (Essentially: a normally-closed gate that is briefly keyed open when locked, but held wide open when unlocked.)

Claim 2 — Claim 1 plus gate-drive pulses, coincidence detector, and disabling of the gate-drive. Adds: the gate is "normally closed"; means coupled to the deflection-generator output produce gate-operating signals at the deflection frequency; those signals momentarily open the gate so sync pulses pass substantially exclusively of other signal effects present with them; detector means coupled to both the deflection generator and the sync source develop control signals indicating synchronous vs. asynchronous operation; the detector controls the gate (conductive/non-conductive); and a further coupling renders the gate-operating-signal-producing means effectively inoperative during asynchronous operation.

• Note on literal wording: the printed claim recites "render said gating apparatus conductive and non-conductive respectively of said synchronizing signal pulses for synchronous and asynchronous operations." Read literally this is inverted relative to the specification, which states the gate is non-conductive during synchronous operation and rendered conductive during asynchronous operation. I flag this as an apparent inconsistency in the printed claim as published on the source page; I have not independently inspected the official printed patent copy to confirm whether it is an OCR/rendering artifact or an error in the original.

Claim 3 (dep. on 2) — The detector's coupling to the deflection generator includes means producing indicating pulses at the deflection frequency, and the detector includes a device detecting coincidence/non-coincidence of indicating pulses and sync pulses.

Claim 4 (dep. on 2) — The oscillator is of the blocking type producing indicating pulses at the deflection frequency, and the detector includes a device coupled to the blocking oscillator to detect coincidence/non-coincidence.

Claim 5 (dep. on 2) — The deflection-generator output circuit includes indicating-pulse-producing means, and the detector device is coupled to that means.

Claim 6 — Gated sync feeding a phase comparator (AFC). Deflection generator with oscillator/frequency-control circuit; sync-pulse source; gating apparatus; means producing gate-operating signals at the deflection frequency to momentarily operate the gate and develop the sync pulses exclusively of other signal effects; a phase comparator whose inputs are coupled respectively to the gate output and the deflection-generator output, producing a time-averaged frequency-control signal representing phase differences; and that signal is coupled to the oscillator's frequency-control circuit.

Claim 7 — Claim 6 variant using dedicated indicating pulses. As in claim 6, but with means coupled to the deflection-wave output circuit producing indicating pulses at the deflection frequency, and the phase comparator inputs coupled respectively to the gate output and to the indicating-pulse-producing means.

• Note: the printed claim 7 text contains a duplicated phrase ("…coupled to said oscillator output circuit to said oscillator frequency control circuit"), which reads as a transcription artifact.

Claim 8 — Combined horizontal + vertical system (embodiment of Figure 3). Respective horizontal and vertical deflection generators, each with an oscillator having a frequency-control circuit; respective H and V sync sources; respective H and V gating apparatus; means producing gate-operating signals at the respective deflection frequencies; the vertical gate output feeds the vertical oscillator's frequency-control circuit; a phase comparator for the horizontal channel (inputs from the horizontal gate output and the horizontal deflection-generator output) supplies a time-averaged frequency-control signal to the horizontal oscillator's frequency-control circuit; means coupled to the phase-comparator output develop signals indicative of synchronous vs. asynchronous operation; those signals render the horizontal and vertical gating apparatus conductive/non-conductive; and render the respective gate-operating-signal-producing means inoperative during asynchronous operation.

Claim 9 — Cross-coupled H/V interlock. Horizontal and vertical deflection generators, each including an oscillator with a frequency-control circuit; respective H and V sync sources; means coupled to one of the deflection-generator output circuits to produce control signals at the frequency of the generated deflection wave; and means responsive to those control signals to impress sync pulses derived from one of the sources of corresponding frequency upon the oscillator frequency-control circuit of the other deflection generator. (This is the "use the horizontal-derived signal to key/control the vertical sync channel" arrangement described in Figure 3.)

Claim 10 — Generic oscillator version, gate-drive disabled on loss of sync. Oscillator with output and frequency-control circuit; sync-pulse source; gating apparatus; gate-operating signals at the oscillator's operating frequency momentarily operate the gate to pass sync pulses exclusively of other effects; detector means coupled to the oscillator and the sync source develop synchronous/asynchronous indicating signals; and those signals render the gate-operating-signal-producing means inoperative during asynchronous operation.

Claim 11 — Generic oscillator version with both gate control and gate-drive disablement. As in claim 10, plus means coupling the detector to the gating apparatus to render it conductive/non-conductive for synchronous/asynchronous operation, together with rendering the gate-operating-signal-producing means inoperative during asynchronous operation.

Claim 12 — Broad "wave generator" version of claim 1. A wave generator with output circuit and frequency-control circuit; a synchronizing-signal source; gating apparatus between them; means normally conditioning the gate during synchronous periods for non-conduction in such a manner that it may be momentarily rendered operative to pass synchronizing signals to the frequency-control circuit; and means active during asynchronous periods to render the gate continuously operative.

Claim 13 — Television-receiver combination, deliberately generic as to state mapping. A wave generator with a frequency and phase control circuit; a source of television signals including a synchronizing component used for that control; signal amplifying means (input from the signal source, output to the control circuit); conditioning means operable to establish either (i) a first state in which the amplifier transfers the television signals continuously to its output, or (ii) a second state in which only the synchronizing component is transferred intermittently; and means responsive to synchronous operation of the wave generator to establish one state and responsive to asynchronous operation to establish the other.

Claim 14 — Claim 13 with the state mapping specified. Same combination, but the responsive means establishes the second state (intermittent transfer of only the sync component) during synchronous operation and the first state (continuous transfer) during asynchronous operation. (The printed text has "elect" for "effect" in the second state — a typographical artifact.)

Claim 15 — Claim 13 with the second state defined as normally blocking, plus disablement of the keying means. The second state "normally prevent[s] transfer of said television signals"; separate means effect intermittent transfer of only the synchronizing component during that second state; the synchronous/asynchronous responsive means select the states; and means operative during the first (continuous) state effectively disable the intermittent-transfer means.

Claim 16 — Closed-loop keyed/unkeyed amplifier version. Source of a television signal with a periodically recurring synchronizing component; an oscillator with a frequency-control terminal and a signal-output terminal; frequency comparison means with two input terminals and an output terminal developing a frequency-control signal applied to the oscillator control terminal; an amplifier capable of operating in an intermittent keyed mode or a continuous unkeyed mode; the amplifier input is coupled to the signal source; the amplifier output and the oscillator output terminal are respectively coupled to the comparison means inputs; the comparison output is coupled to the oscillator control terminal; first-control-signal-responsive means put the amplifier in the keyed mode (intermittent during sync-component periods); second-control-signal-responsive means put it in the unkeyed mode (continuous); and means derive those control signals from the comparison means and impress them on the amplifier, the control signals representing the timing relationship of the oscillator and the synchronizing component.

Key technical points (from the specification)

• Three disclosed embodiments: Fig. 1 (block diagram), Fig. 2 (single sweep oscillator, using vacuum-tube coincidence detector 61), Fig. 3 (both horizontal and vertical, using a noise-immunizing tube 106 driven by the horizontal AFC output resistor 94).
• Two-part gate control: (a) a DC threshold/bias control (gate threshold control 18) and (b) AC gate-operating pulses 19 clipped from the sawtooth peaks 24 by clipper 21/53/84/102, optionally partially integrated to broaden the gate-opening window.
• Figure 3 uses an AFC phase comparator (diodes 86, 87) rather than a coincidence detector for the horizontal channel; the noise-immunizing tube responds to increased AC amplitude across the AFC output resistor and raises a positive voltage that (i) holds both gates open continuously, (ii) raises both clipper levels (self-disabling the keying pulses), and (iii) is also cross-fed to control the vertical channel — the basis for claim 9.
• Stated advantages: noise immunity without long-time-constant AFC filtering, fast initial sync/resync, use of the composite television signal directly without a sync separator in some cases, and applicability to either or both horizontal and vertical sweep oscillators.
• Explicit disclaimer in the specification: the inventor notes the coincidence detector need not be a tube that increases conduction on loss of coincidence; it could instead be arranged as a cathode follower with a low-impedance cathode circuit.

Items I could not confirm (stated explicitly rather than guessed)

• I found no litigation, CAFC 2026 docket, IPR/PGR, or reissue/reexamination activity for this patent. Its term expired long ago (anticipated expiration June 12, 1973), so it is in the public domain and was never subject to AIA-era post-grant proceedings.
• I could not verify a formal USPTO abstract; the "Definitions"-style summary on the Google Patents page is a synthesized abstract, not an original field.
• I did not independently inspect the official printed patent copy to resolve the apparent internal inconsistency in claim 2 (and the duplicated phrase in claim 7); those are flagged as possible transcription artifacts rather than confirmed defects.

Primary source: https://patents.google.com/patent/US2750498/en (fetched 2026-09-27).

I'll search for litigation involving US patent 2,750,498 across patent litigation databases.

Let me search more targeted patent litigation databases.

Let me do a final round of checks on litigation-specific databases.

Litigation Search Report — U.S. Patent No. 2,750,498

Bottom line

No litigation involving U.S. Patent No. 2,750,498 was found. I searched patent-litigation sources (Unified Patents litigation/PTAB portals, CourtListener/Free Law Project, Docket Alarm material, and general web indices) and could not identify any district court action, CAFC appeal, ITC investigation, PTAB proceeding, or other adversary proceeding in which U.S. 2,750,498 was asserted, challenged, or adjudicated.

Verified bibliographic facts (from the authoritative patent record)

These matter because they explain why litigation is essentially nonexistent and why the search hits below are false positives:

The patent has been expired for more than five decades and concerns 1950s-era analog TV deflection/synchronization circuitry. No live assertion activity is plausible.

Why the "2750498" search hits are not this patent

The searches returned several documents containing the string "2750498," but none is US 2,750,498. Per the operating rules I interpret these literally and do not treat them as the same patent:

• CA 2,750,498 — "Intra-operative blood recovery system," ProCell Surgical Inc. (Canadian patent, published 2016). Different jurisdiction, different subject matter.
• EP 2 750 498 A1 — "Snap trap" (European patent application, animal trap). Different jurisdiction and subject.
• JP 特許第2750498号 — Japanese patent for a wood moisture-content measuring device. Different jurisdiction.
• RU 2750498 C2 — Russian patent for an absorbent sheet/article. Different jurisdiction.
• Brazilian STJ case "AGRAVO EM RECURSO ESPECIAL Nº 2750498" (2024/0356866-6) — a Brazilian court docket number, unrelated to US patents.
• FEI Number 55-2750498 (Holy Spear IT, LLC, Florida) — an IRS employer identification number, not a patent.
• Aten International v. Uniclass Technology, C.D. Cal. 2:15-cv-04424 — refers to a distinct "'275 patent" in an unrelated power-management dispute; it is not US 2,750,498.
• Power Mosfet Technologies v. Siemens/Infineon (Fed. Cir. 2004) and the Amazon "'049 patent" testimony — unrelated patents.

Search coverage and caveats

• The "cited by" references on the Google Patents page (e.g., US 2,875,332; US 3,061,674; US 3,172,951) are later patents that cite 2,750,498 as prior art — citations, not litigation.
• Unified Patents' litigation case-list portal was the intended primary source; the portal's public pages surfaced no case keyed to this patent.
• Caveat: pre-1990s patent suits are poorly indexed in modern docket aggregators, and there was no comprehensive public docket database for the 1956–1973 term of this patent. I cannot affirmatively rule out a mid-20th-century infringement action that was never digitized. Based on everything available, however, I found no evidence of any such suit, and I will not fabricate plaintiff/defendant/case-number details.

If you need a belt-and-suspenders confirmation for the historical window, the practical next steps would be the USPTO's Patent Assignment/PatentCenter records, the Federal Records Centers' archived district court files, and the Westlaw/Lexis historical case databases (no pre-1990 patent case for this number surfaced in any indexed source I could reach).

Proceedings overview

Total AIA trial proceedings on file for US 2,750,498: zero. The structured "PTAB proceedings on file" block (USPTO Open Data Portal) returns no IPR, PGR, or CBM entries, and independent web searching surfaced no PTAB petition, institution decision, Final Written Decision, or Federal Circuit appeal involving this patent. The breakdown is therefore 0 active / 0 invalidated / 0 sustained / 0 settled / 0 institution denials — a structurally empty litigation posture, not a "hardened" one: US 2,750,498 issued on 1956-06-12, ran its 17-year term from grant, and reached anticipated expiration on 1973-06-12, roughly 39 years before the first IPR was ever filed. Any defendant receiving a demand letter citing this patent is not facing an IPR question at all; they are facing an expired patent whose claims cannot be infringed as a matter of law by post-1973 conduct.

Proceedings

None. There are no proceeding numbers to report, and I will not synthesize any.

For completeness on the diligence trail:

• USPTO ODP (canonical source in the prompt): no AIA trial proceedings, most recent ingest.
• USPTO PTAB E2E / PTAB Decisions searches: no petition or decision record for 2,750,498 or for inventor "Frederick M. Arbuckle" / assignee "RCA Corp" in the TV-synchronization art.
• CourtListener / CAFC docket: no appeal arising from a PTAB proceeding on this patent (there can be none without an underlying FWD).
• Google Patents bibliographic record: Expired - Lifetime; filing date 1952-07-05; priority 1952-07-05; granted 1956-06-12; anticipated expiration 1973-06-12. Source: https://patents.google.com/patent/[US2750498A](/patent/US2750498A)/en

AIA-availability analysis (why the empty list is expected, not an oversight):

Strategic summary

Claim status of US 2,750,498 (all 16 claims): UNTESTED — and untestable in any practical sense. No claim of this patent has ever been canceled, confirmed, or construed by the PTAB, because no AIA trial was ever filed. The claim set as issued runs claims 1–16, including an independent apparatus claim 1 (gated sync amplifier normally non-conductive, rendered continuously conductive during asynchronous operation), independent claim 2 (normally-closed gate + gate-operating signals + coincidence detector), independent claims 6 and 7 (gate plus phase comparator / AFC), independent claim 8 (combined horizontal + vertical gating with a phase comparator on the horizontal side), independent claim 9 (cross-coupling one deflection generator's control signals to the other), independent claims 10 and 11 (generic oscillator versions), independent claim 12 (generic wave generator), independent claims 13, 14, and 15 (television-receiver combinations in terms of "first/second operating states" of an amplifier), and independent claim 16 (keyed-mode vs. unkeyed-mode amplifier with a frequency comparison means). "Untested" here is not a vulnerability signal in the ordinary sense — it means the PTAB docket is irrelevant to the patent's enforceability, because the patent has been dead for over half a century. The subject matter (gated sync amplifiers, noise immunity, AFC phase detectors, flyback-derived indicating pulses) is now public-domain, foundational television engineering, and substantial portions of it are reflected in the very RCA/Philco/DuMont prior art cited on the face of the patent (US2141343, US2207048, US2212648, US2240420, US2265290, US2277000, US2358545, US2561817, US2685033).

Estoppel landscape: There is no § 315(e)(2) estoppel to analyze, because there is no petitioner and no FWD. § 315(e)(2) estoppel attaches only to a petitioner that obtains an FWD; no such entity exists here. Similarly, no § 315(b) one-year bar clock has ever started against anyone. If a currently-asserted defendant wanted to seek an AIA trial anyway, the only formal bar is the practical one: no live patent right to invalidate, and no possibility of meaningful relief. The real prior art on file — the nine U.S. references cited during original prosecution (1938–1954 vintage) plus the eight third-party citations in the "Cited By" table (e.g., US2875332 RCA, US3061674 Philips, US3172951, US3865973 Hitachi, US3937876 Philips, US4001715 NEC) — is freely usable by anyone today under § 102(b) as long-expired printed publications, with no estoppel exposure whatsoever, since no AIA trial was ever brought.

Pattern signals: None of the usual monetization markers are present. There is no repeat petitioner (no petitioner at all), no PTAB appeal history, and no defensive aggregator (Unified Patents, RPX, Open Invention Network) in the chain — aggregators do not file against 1950s-expired patents because there is nothing to invalidate and no assertion to defend against. The RCA Corp assignment reflects the original 1952 corporate filing (Radio Corporation of America, a Delaware corporation), not a modern assertion vehicle. The absence of PTAB activity here is not the "well-asserted patents eventually attract IPRs" signal discussed in the prompt — that heuristic applies to live patents; the correct inference for a 1973-expired patent is that no one has asserted it, because no one could assert it successfully.

Number-collision warning (relevant if you are researching by number): searching "2750498" produces numerous unrelated hits that are not this patent and must not be mistaken for PTAB or litigation activity on it: Corning's glass-composition "'498 patent" (IPR petitions at PTACTS involving Miwa '535 and Chacon; ITC written-description findings), Canadian patent 2,750,498 (Procell Surgical, intra-operative blood recovery), RU2750498C2 (absorbent sheet), EP2750498A1 (snap trap), FR 2 750 498 A1 (Freyssinet), JP 2750498 (wood moisture meter), and DE 199 27 498 A1 (Volkswagen). None of these relate to US 2,750,498. Similarly, the several court decisions referring to a "'498 patent" (Neonatal Prod. Grp. v. Shields, HIP, Inc. v. Hormel, Braintree v. Lupin) involve entirely different patents.

Recommended next steps

1. If you received a demand letter citing US 2,750,498: treat it as presumptively improper. The patent's term expired 1973-06-12 (record: https://patents.google.com/patent/US2750498A/en). There is no maintenance-fee scenario to check — maintenance fees under 35 U.S.C. § 41(b) apply only to patents filed on or after 1980-12-12, and this patent's 17-year term from the 1956-06-12 grant had already run. Direct infringement under § 271(a) requires making, using, offering to sell, or selling "a patented invention" during the term; for post-1973 activity there is nothing left to infringe. Consider a response citing the expiration date and, if the letter is part of a broader pattern, a § 285 / state-law unfair-competition posture.
2. Do not spend budget on an IPR. There is no FWD to distinguish, no claim to invalidate, and no estoppel benefit to purchase. No PTAB trial-stage milestones apply because there is no proceeding — no institution-decision deadline, no 1-year statutory FWD deadline, no oral hearing.
3. If the assertion targets pre-1973 conduct (which would be extraordinary), the defensive playbook is historical, not PTAB-based: the nine references cited in the 1956 prosecution plus the intervening 1938–1954 art, § 102(b)/§ 103 obviousness, laches, and the 20-year/17-year term bar under the pre-1995 statute.
4. Verification sources if you want to confirm the null result yourself: USPTO PTAB E2E trial search (https://ptacts.uspto.gov/ptabweb/), USPTO PTAB decisions library (https://www.uspto.gov/patents/ptab), CAFC docket (https://cafc.uscourts.gov/), and CourtListener (https://www.courtlistener.com/) — I found no docket or opinion on any of these referencing US 2,750,498.

Confidence note: I have high confidence in the "no PTAB proceedings" conclusion for this patent, given (i) the ODP structured block, (ii) the 1973 expiration date reflected in the authoritative patent record, and (iii) the failure of multiple targeted searches to surface any petition, decision, or appeal. I found no evidence of any PTAB or Federal Circuit activity, and I did not locate any proceeding number to report.

I'll start by pulling the authoritative record and checking for any recorded assignments.

Assignment records didn't surface in that pass. Let me probe the Assignment Center API directly and verify the corporate-history facts.

Ownership Analysis — US 2,750,498

Scope note first: I could not reach assignmentcenter.uspto.gov interactively from this environment, so I attempted to surface recorded assignments for US 2,750,498 through indexed sources: the Google Patents record (which mirrors USPTO legal events), USPTO's own assignment-database documentation, and open web search. No assignment records for this patent surfaced anywhere. The detailed finding is in the Assignment timeline section below.

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Inventors

Unusual-pattern check: none detectable, and this is a null finding rather than a clean bill of health. This is a single-inventor patent, so the classic "all inventors departed within 12 months" tell cannot be evaluated — there is no co-inventor roster to track and no inventor-employment data available for a 1952 filing. No inventor name from this patent reappears in any later ownership record I could retrieve (there are none). I found no evidence of any kind of inventor-side activity.

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Original assignee

Radio Corporation of America (RCA), a corporation of Delaware — named on the face of the issued patent, with the assignee name carried in the Google Patents bibliographic record as "RCA Corp" (current assignee field).

• Primary line of business: RCA in 1952 was the dominant U.S. consumer-electronics manufacturer (television receivers, radios, phonographs), a vacuum-tube and electron-optics manufacturer, the owner of NBC, a defense-electronics contractor, and the operator of RCA Laboratories (Princeton, N.J.). RCA was the leading U.S. black-and-white television set maker during the period this patent was filed and granted.
• Did they ship a product embodying the claims? Almost certainly yes by reasonable inference — the claims are directed to noise-immune synchronizing circuitry for the horizontal and vertical deflection systems of a television receiver (claims 1, 2, 8, 12–16), and Figure 3 is expressly a complete television receiver block diagram. RCA was shipping television receivers with exactly this functional block set throughout the 1950s. Caveat: I could not verify a specific RCA model against these claims from the sources available; treat "RCA shipped a practicing product" as a high-confidence business inference, not a documented citation.
• Current status: No longer an operating entity. RCA Corporation was acquired by General Electric in 1986; GE retained NBC and select businesses and sold the RCA consumer-electronics business (including the RCA and GE consumer brands) to Thomson S.A. of France in 1987–88. The RCA brand has since been licensed to third parties (notably Voxx International). RCA Corporation does not exist as an operating company today.

Critical timing point for the whole analysis: the patent expired 1973-06-12, 17 years after grant (pre-1995 term rule; no maintenance fees applied to patents granted before 1980-12-12, so there is no fee-lapse event either). The patent therefore expired seven years before the USPTO assignment database's coverage begins and thirteen years before RCA was acquired by GE. Any RCA portfolio transaction in 1986 could not have carried this asset.

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Assignment timeline

No recorded assignments were found for US 2,750,498 — and for this patent that outcome is expected and structural, not merely a search gap.

What the record does show:

• Google Patents legal events for this patent list only: application filed (1952-07-05) → priority to US297252A → application granted (1956-06-12) → publication of US2750498A (1956-06-12) → anticipated expiration 1973-06-12 → status "Expired – Lifetime." There is no assignment, security-agreement, merger, change-of-name, license, release, or correction event in that legal-events feed (source).
• The original inventor→RCA conveyance is evidenced only by the patent front page ("assigner to Radio Corporation of America"), not by a reel/frame in the online database. Its execution date is not available in any source I could retrieve.
• Why no reel/frame exists online: the USPTO's patent assignment database "contains all recorded Patent Assignment information back to August 1980" (USPTO Assignment Database webinar; same coverage statement in Finnegan, Prosecution Pointer No. 119). This patent's entire enforceable life (1956–1973) predates that coverage window, so even a fully recorded 1952–1956 RCA assignment would not appear in a Patent Number search.

Per the search protocol, I would stop here. I am continuing with the remaining required sections in abbreviated form, but every one of them must be read against this single fact: there is no post-1980 ownership chain of any kind to analyze, and the asset has been expired and unassertable since June 1973.

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Timeline diagram

timeline
    title Ownership context for US 2750498
    1952 : Application filed by RCA
         : Arbuckle sole inventor
    1956 : Patent issued to RCA
    1973 : Patent term expired
    1980 : USPTO assignment database begins
    1986 : RCA acquired by General Electric

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NPE / troll-pattern signals

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Verdict

Insufficient data — and the definition fits precisely: no records, or only the original assignment. There is exactly one ownership event in this patent's history that is documented anywhere I could reach: the original inventor→RCA assignment evidenced on the patent face, with no reel/frame retrievable because the USPTO's assignment database coverage begins August 1980 and this patent expired 1973-06-12. No shell transfer, no known asserter, no repeat correspondent, no cascading chain, no pre-litigation transfer, no bankruptcy sale, and no defensive aggregator appears — so there are zero NPE-pattern signals, and equally zero affirmative evidence of clean operating-company ownership beyond the assignee-of-record.

Practical conclusion: this is not an NPE situation and cannot become one. The asset has been in the public domain since June 1973, RCA Corporation has not existed as an operating entity since its 1986 acquisition by General Electric, and no asserting entity would have anything to acquire. Anyone reporting an NPE chain on "2,750,498" is almost certainly conflating it with the unrelated foreign registrations listed under signal 5.

Verify at:

• USPTO Assignment Center (post-2025-09-27 unified search): https://assignmentcenter.uspto.gov/
• Legacy Patent Assignment Search landing page: https://assignment.uspto.gov/patent/index.html
• Bibliographic / legal events cross-check: https://patents.google.com/patent/US2750498/en

Two honesty caveats: (1) I was unable to query the Assignment Center's live index directly, so I cannot rule out that a pre-1980 reel/frame exists on paper in the USPTO's pre-1980 records — those are historically searchable only through the USPTO's legacy microfilm/reel holdings, not through the online database, and no correspondent data would be exposed for them. (2) I did not fabricate any reel/frame, correspondent name, execution date, or recording date; where the data does not exist, the section says so.

I'll verify the USPTO record and characterize each cited reference. Let me run targeted lookups on the prior-art patents named on the face of US 2,750,498.

Now let me verify the remaining cited references.

Prior-Art Analysis — U.S. Patent No. 2,750,498

0. Identifier verification (do not conflate)

The USPTO identifier 2750498 resolves to exactly one document:

Per the operating rule, I treated this literally and did not fold in the many unrelated documents that carry the string "2750498" (Canadian 2,750,498 ProCell blood-recovery; JP 2750498 wood-moisture meter; RU2750498C2; ES2750498T3; EP2750498A1 "Snap trap"; a Brazilian STJ docket number; a Florida FEI). None of those are this patent.

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1. The nine references cited on the face of US 2,750,498

All nine are U.S. patents cited by the Examiner during the 1952–1956 prosecution. Their numbers, titles, assignees and dates are taken from the "References Cited" table of the patent record.

A threshold point that governs the whole answer: the task asks which claims each reference "potentially anticipates under 35 U.S.C. § 102." On this record, no single one of the nine references discloses every element of any one of claims 1–16. Every one of these references is properly § 103 (obviousness) art, i.e., they are cited for what they suggest in combination, not as standalone anticipations. I give the closest § 102 read for each below, but I flag plainly where the honest conclusion is "material, not anticipatory," rather than manufacture an anticipation that the references do not support. (This is consistent with — and builds on — the earlier obviousness section, where the primary combinations were Wendt '545 + Volz '033, with Knick '290 supplying the threshold-disable feature.)

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2. Reference-by-reference

1) US 2,141,343 — Campbell, "Electrical system" (Philco)

• Full citation: US 2,141,343, R. L. Campbell, assignor to Philco Radio & Television Corp.; filed 1935-06-07; granted 1938-12-27.
• Brief description (verified): Sawtooth sweep generating system with a peak/limit signal derived from the sweep, in which an input tube is deliberately biased off between synchronizing pulses and the bias "gradually diminish[es]… effective to block the tube until just before the next synchronizing signal is applied." The specification states the purpose of this blocking is that it "prevents extraneous voltages, such as might be due to static or the like, from energizing the circuit." A signal-amplitude feedback (AGC-like) adjusts the applied sync amplitude to keep deflection amplitude constant.
• § 102 read: Material to the "normally conditioned … for non-conduction" limitation of claims 1, 2 and 12, and in fact its stated rationale (blocking the tube between sync pulses to reject "static") is the same noise-immunity rationale the '498 gives for its gated amplifier. However, it lacks the '498's second state (detector-driven continuous conduction during asynchronous operation), the deflection-frequency gate-operating pulses, and any coincidence/phase detector. Assessment: not an anticipation of any claim; strongest § 103 art for the "gate normally closed between sync pulses" element of claims 1/2/12.

2) US 2,207,048 — Campbell, "Television transmitting system" (Du Mont)

• Full citation: US 2,207,048, R. L. Campbell, assignor to Allen B. Du Mont Laboratories, Inc.; filed 1939-06-01; granted 1940-07-09.
• Brief description (verified): Television transmitting system using a cathode-ray pick-up tube; horizontal and vertical sweep circuits locked by synchronizing signals; peaks of a sawtooth wave are selected out and combined to develop blanking pulses (grids overbiased so plate current flows only at the extreme positive peak of the sawtooth — i.e., level-clipping of the sweep to derive narrower pulses).
• § 102 read: Relevant to the clipper-derived pulse generation that the '498 uses to key its gate (clipper 21/53, gate pulses 19), and to the partial-integration/peak-picking idea. But it is a transmitter blanking system, with no sync-gating, no coincidence detection, no AFC. Assessment: not an anticipation; § 103 background art for the "clip the sawtooth peak to derive a control pulse" sub-step.

3) US 2,212,648 — "Synchronizing pulse generator" (RCA)

• Full citation: US 2,212,648, assignor to RCA Corp.; filed 1939-01-28; granted 1940-08-27. (The '498 reference list shows the inventor name only as "Poeh"; I could not corroborate that spelling from the sources I retrieved, so I do not rely on the name.)
• Brief description (verified): Synchronizing-pulse generator with two oscillators locked in a master–slave chain by AFC — "one A.F.C. circuit is utilized for locking a low frequency oscillator in with the power line while another A.F.C. circuit is utilized for locking a high frequency oscillator in with the first oscillator." Includes clipping/limiting, differentiating to make narrow pulses, mixing narrow pulses with a high-frequency wave, a diode that passes only peaks (biased by an adjustable tap) and a storage circuit producing the AFC voltage, and an AFC control path with a deliberately slow time constant so fast line-voltage variation does not change the oscillator frequency.
• § 102 read: This is the reference most relevant to claim 9 (a control signal derived from one generator's output used to synchronize the other generator) and to the AFC/time-constant backdrop the '498 disparages. It does not disclose a gated sync amplifier or the async continuous-conduction state, and it is a generator, not a receiver deflection system. Assessment: not an anticipation of claim 9; § 103 art supporting the cross-coupled/one-oscillator-locks-the-other topology (building on the earlier section's Combination 3).

4) US 2,240,420 — Schnitzer, "Electrical system" (Philco)

• Full citation: US 2,240,420, A. Schnitzer, assignor to Philco Radio & Television Corp.; filed 1939-05-11; granted 1941-04-29.
• Brief description (verified for this number): System for fading/combining two video signals, in which transfer means (amplifiers) are rendered operative or blocked during fractions of each frame, and the switching/blanking control signal is derived by clipping a triangular wave at a level slightly above/below a fixed amplitude — expressly noting that "the mean duration of a signal so derived is dependent upon the amplitude level at which it is derived."
• § 102 read: The clipping-level-determines-pulse-duration teaching is conceptually parallel to the '498's clipper-level control (22 / 55) that sets how long the gate stays open — and to the '498's discussion that "the higher this clipping level can be set … the shorter the interval … the greater the noise immunity." But Schnitzer is a video-fading system with no sync path, no oscillator frequency-control circuit, and no gate/holding arrangement. Assessment: not an anticipation of any claim; limited § 103 relevance to the clipper-level-sets-gate-duration element.

5) US 2,265,290 — Knick, "System of synchronizing television transmissions" (Fernseh)

• Full citation: US 2,265,290, assignor to Fernseh GmbH; filed 1937-12-30; granted 1941-12-09.
• Brief description (verified in the prior session): Externally excited sawtooth generator in which a synchronizing impulse renders a discharge tube conductive and a derivative of that condition terminates the discharge (pulse-initiated, pulse-terminated sweep). Includes "a biased rectifier responsive to a predetermined value of the voltage drop across said resistance element and effectively coupled to said discharging means for rendering said last-named means inoperative."
• § 102 read: The threshold-responsive device that renders the sweep-initiating element inoperative at a predetermined level is structurally the same control function as the '498's clipper-level control that is raised above the sawtooth peaks during async so that no gate pulses are produced (the "render the signal-producing means effectively inoperative" limitation of claims 2, 8, 10, 11). But Knick is not a sync-vs-loss-of-sync detector and has no gated sync amplifier. Assessment: not an anticipation; it is the key § 103 reference supplying the disable-the-initiating-means element of the claims that require disabling the gate-pulse source.

6) US 2,277,000 — Bingley, "Synchronizing system" (Philco)

• Full citation: US 2,277,000, assignor to Philco Radio & Television Corp.; filed 1940-09-17; granted 1942-03-17.
• Brief description: I did not verify this reference's disclosure in this session (the lookup hit the tool-step limit before returning). I therefore attribute no specific teaching to it and do not map it to any claim. By number/title/assignee it is a 1940s televison synchronizing system, i.e., general background art in the same field.
• § 102 read: Cannot assess — not verified. I will not infer an anticipation from the title alone.

7) US 2,358,545 — Wendt, "Television system" (RCA) ★ strongest single reference

• Full citation: US 2,358,545, assignor to RCA Corp.; filed 1941-07-31; granted 1944-09-19.
• Brief description (verified in the prior session): The classic keyed diode-bridge AFC — a blocking oscillator with iron-core feedback transformer; a sawtooth discharge tube and condenser; retrace ("flyback") pulses taken from the deflection circuit, integrated by an R-C network, applied across one diagonal of a four-diode bridge; differentiated sync pulses applied across the other diagonal as keying pulses; a storage condenser holding the averaged control voltage fed back to control oscillator frequency/phase. The bridge is non-conducting unless a sync pulse keys it. Wendt also shows two AFC loops interlocking oscillators.
• § 102 read: This is the reference that most closely parallels the '498's Figure 3 horizontal AFC (diodes 86/87, bridge resistors 88/89, output resistor 94, coupling network 95, oscillator 96, flyback pickoff coil 101). It is therefore the closest art to:
  • Claims 3, 4, 5 — indicating pulses at the deflection frequency (flyback pulses / blocking-oscillator pulses) fed to a coincidence/phase-comparison device.
  • Claims 6, 7 — phase comparator producing a time-averaged frequency-control signal from sync and locally derived indicating pulses.
    But Wendt keys the bridge with the incoming sync pulses themselves and has no separate gated sync amplifier driven by clipped-sweep gate pulses, and no async "continuously conductive" state. Assessment: not a full anticipation of 6/7 (missing the gate + gate-operating pulses), but the primary § 103 reference for the AFC/phase-comparator half of the disclosure (Combination 1 in the earlier section).

8) US 2,561,817 — Parker, "Automatic frequency control circuit" (Avco)

• Full citation: US 2,561,817, assignor to Avco Manufacturing Corp.; filed 1950-02-02; granted 1951-07-24; classified H04N 5/12 (television synchronizing).
• Brief description: Not verified in this session beyond bibliographic data and classification (television-synchronization AFC). I attribute no specific teaching to it.
• § 102 read: Cannot assess — not verified. Its significance is as corroboration that AFC voltage generation for TV sync was routine by 1950, supporting the § 103 treatment of the AFC claims (6/7/8) rather than a § 102 anticipation.

9) US 2,685,033 — Volz, "Beam deflection control for cathode-ray devices" (RCA) ★ closest to the gating claims

• Full citation: US 2,685,033, assignor to RCA Corp.; filed 1951-01-02; granted 1954-07-27. Because it was filed before Arbuckle's 1952-07-05 filing date (but published after), it is available as a pre-AIA § 102(e) reference and is fully usable for § 103.
• Brief description (verified in the prior session): A phase-control system in which sync/controlling pulses are applied to a comparison tube's control electrode while locally derived keying pulses ("pulses in step with said electrical apparatus") are applied to its cathode, with the sawtooth generator and oscillator driven thereby. The specification states verbatim: "The effects of impulse noise are greatly reduced since impulse noise occurring outside the local keying pulse has no effect on the tank circuit."
• § 102 read: This is essentially the gating concept of the '498 — sync reaches the frequency-control element only during a locally generated gate — expressly for impulse-noise immunity. It is therefore the closest single reference to claims 1 and 12 (and, with the detector elements, claim 2). But Volz does not disclose the '498's two-state behavior (detector lowering the gate threshold so the gate is continuously conductive during asynchronous operation, while the gate-pulse source is disabled). Assessment: not a complete anticipation of claims 1/12 (missing the async continuous-conduction state), but the primary § 103 reference for the gating element.

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3. Bottom-line mapping (as requested)

Net conclusion: On the nine references cited in the patent itself, none individually anticipates any of claims 1–16 under § 102 as I read the record. The references cited by the Examiner are, without exception, § 103 combination art. The strongest pairings are Wendt US 2,358,545 (the AFC/phase-comparator and flyback-indicating-pulse half) with Volz US 2,685,033 (the locally keyed, noise-immune gate half), reinforced by Knick US 2,265,290 for the threshold device that disables the gate-pulse source — exactly the combinations developed in the earlier obviousness section. Campbell US 2,141,343 is a notable sleeper: its express statement that the input tube is blocked between sync pulses "so that extraneous voltages, such as might be due to static, [cannot] energize the circuit" is the same noise-immunity rationale the '498 advances.

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4. Caveats (stated, not glossed)

1. Verification status. I verified the substance of US 2,685,033, 2,358,545, 2,212,648, 2,265,290, 2,141,343 and 2,207,048 plus US 2,240,420, and the bibliographic data of the rest. I did not verify the disclosures of US 2,277,000 or US 2,561,817 (tool-step limit reached), so no teaching is attributed to them and they are not mapped to any claim above.
2. Inventor name for US 2,212,648. The '498 reference list shows "Poeh"; I could not corroborate it and have not relied on it.
3. § 102 vs § 103 framing. The task's framing assumes anticipatory references; the actual record does not support single-reference anticipation. I have reported that truthfully rather than forcing a § 102 match. The disqualifying element against full anticipation in nearly every case is the '498's two-state control — detector-driven continuous conduction on loss of synchronism combined with disabling the gate-pulse source — which no single cited reference shows.
4. Claim-drafting anomalies (carried forward from the earlier section): claims 2 and 11, as printed in the retrieved text, recite the gate as "conductive and non-conductive respectively … for synchronous and asynchronous operations," which reads inverted against the specification; claims 2, 7, 8 and 11 are truncated in the retrieved text. A § 102/§ 103 mapping should be resolved against the official printed patent copy before being relied on.
5. "Cited By" is not prior art. The eight later documents that cite 2,750,498 (e.g., US 2,875,332 RCA; US 3,061,674 Philips; US 3,415,948 Xerox; US 3,865,973 Hitachi) are subsequent to the '498 and cannot be § 102 art against it.
6. This is a technical prior-art assessment, not legal advice. The patent expired 1973-06-12; nothing here revives or affects its (expired) status.

Primary source: https://patents.google.com/patent/US2750498/en (References Cited table and specification).

I'll ground this analysis in the actual cited prior art. Let me pull the subject matter of the key references.

Let me characterize the remaining cited references.

Obviousness Analysis — U.S. Patent No. 2,750,498

"Synchronization of television deflection systems" (Arbuckle; RCA; filed 1952‑07‑05; granted 1956‑06‑12)

Note on context: The earlier litigation section of this analysis concluded that no court has ever construed or invalidated these claims and that the patent expired 1973‑06‑12. This is therefore a forward‑looking, hypothetical § 103 assessment built on the nine references the Examiner cited in the patent itself, not a reconstruction of any actual validity contest.

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1. Governing law and status of the art

The application was filed 1952‑07‑05 (no earlier priority claimed), so pre‑AIA 35 U.S.C. § 103(a) governs on its face. Two consequences matter:

The Volz point is important: at the time of the allowed case the Examiner had before him a reference (Volz) that was filed 18 months before Arbuckle's application, by Arbuckle's own assignee, and that expressly claims the noise‑immunity benefit of keying sync pulses with locally generated pulses. (Pre‑AIA § 103(c) common‑ownership disqualification did not exist in 1952–56 and would not reach a pre‑1999 filing anyway.)

Because any modern challenge would be decided under current law, both tests matter: under the pre‑KSR teaching‑suggestion‑motivation ("TSM") framework that governed 1956 practice, the patentee has a real argument; under KSR Int'l Co. v. Teleflex, Inc., 550 U.S. 398 (2007), several of these claims look plainly invalid.

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2. What the cited art actually teaches

Verified this session (direct sources):

• US 2,685,033 — Volz, "Beam deflection control for cathode‑ray devices" (RCA), filed 1951‑01‑02, granted 1954‑07‑27. A phase‑control system in which sync/controlling pulses are applied to a comparison tube's control electrode while locally derived keying pulses ("pulses in step with said electrical apparatus") are applied to its cathode, with the sawtooth generator and oscillatory circuit driven thereby. The specification states verbatim: "The effects of impulse noise are greatly reduced since impulse noise occurring outside the local keying pulse has no effect on the tank circuit." This is the gating concept of the '498 — sync reaches the frequency‑control element only during a local gate — stated as a noise‑immunity rationale. (https://patents.google.com/patent/[US2685033A](/patent/US2685033A)/en)
• US 2,358,545 — Wendt, "Television system" (RCA), 1944‑09‑19. The classic keyed diode‑bridge AFC: a blocking oscillator with iron‑core feedback transformer; a sawtooth discharge tube and condenser; retrace ("flyback") pulses taken across the deflection coils, integrated by an R‑C network, and applied across one diagonal of a four‑diode bridge; differentiated sync pulses applied across the other diagonal as keying pulses; a storage condenser holding the averaged control voltage, fed back to control oscillator frequency/phase. Wendt expressly notes the bridge is non‑conducting unless a sync pulse keys it, and that one AFC loop locks a low‑frequency oscillator to the line while a second AFC loop locks the high‑frequency oscillator to the first. This is, element for element, the horizontal AFC of Figure 3 of the '498 (diodes 86/87, bridge resistors 88/89, output resistor 94, coupling network 95, oscillator 96, auxiliary coil 101 flyback pickoff) and the blocking‑oscillator/sawtooth combination of Figure 2.
• US 2,212,648 — "Synchronizing pulse generator" (RCA), 1940‑08‑27 (inventor name in the '498 reference list appears as "Poeh"; I could not corroborate that name field and do not rely on it). Discloses clipping a wave at a fixed level to derive narrow pulses, automatic frequency control of an oscillator by a detected/averaged phase‑error signal fed through a deliberately slow time constant, the master‑slave interlocking of two oscillators (line oscillator locked to the frame oscillator, which is itself locked to the power line), and deriving line‑rate pulses from a higher‑frequency source.
• US 2,265,290 — Knick, "System of synchronizing television transmissions" (Fernseh), 1941‑12‑09. Externally excited (non‑self‑oscillatory) sawtooth generator in which a synchronizing impulse renders a discharge tube conductive and a derivative of that condition terminates the discharge — i.e., pulse‑initiated, pulse‑terminated sawtooth control — plus the key teaching for our purposes: "a biased rectifier responsive to a predetermined value of the voltage drop across said resistance element and effectively coupled to said discharging means for rendering said last‑named means inoperative." That is a threshold‑responsive device that disables the sawtooth‑initiating element once a predetermined level is reached — structurally the same control function as the '498's clipper‑level control (22) that raises the clipping level above the sawtooth peaks so no gate pulses 19 are generated.

Not verified in this session (I list only what the record itself recites — number, title, date, assignee — and do not attribute disclosure content to them):

Titles/assignees above are taken from the "Citations" listing accompanying the '498 record (https://patents.google.com/patent/[US2750498](/patent/US2750498)/en).

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3. The claims, grouped

⚠️ Two drafting flags that bear directly on any validity analysis. (i) Claims 2 and 11, as printed in the retrieved text, recite rendering the gate "conductive and non‑conductive respectively of said synchronizing signal pulses for synchronous and asynchronous operations." Literally read, that is inverted relative to the specification, which states the gate is cut off at or above peak sync level during synchronism and made continuously conducting on loss of coincidence. (ii) Claims 2, 7, 8 and 11 are truncated/garbled in the retrieved text. Both facts make the claims vulnerable on § 112 grounds and complicate any § 103 mapping, and I flag them rather than silently "fixing" them.

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4. The obviousness combinations

Combination 1 (primary): Wendt '545 + Volz '033

Both are RCA patents in the identical field (television deflection synchronizing) addressed to the identical problem (false sync from impulse noise, e.g., ignition interference). Wendt supplies the AFC/phase‑comparator half of the disclosure — the keyed diode bridge, the stored/averaged control voltage, the flyback indicating pulses, the blocking oscillator and sawtooth generator. Volz supplies the missing half: replacing a sync‑keyed gate with a locally keyed gate ahead of the frequency‑control element, and expressly states the noise‑immunity reason for doing so.

The motivation is not speculative. Wendt's own bridge is keyed by the incoming sync pulses themselves; a noise pulse exceeding the R‑C bias built across Wendt's 66–67 will therefore key the comparison and perturb the stored charge. The '498 specification itself names this as the problem and identifies the prior solution — long‑time‑constant AFC — as its drawback. A PHOSITA of 1952 reading Wendt and Volz together had both the problem and both halves of the solution in front of him. Putting a known gate in a known signal path to perform its known function (blocking extraneous signals and passing only the desired ones) is the paradigm KSR "combination of familiar elements according to known methods," with the predictable result identified in advance by Volz.

This combination renders claims 1, 6, 7, 10 and 12 obvious, and (with the "indicating pulse" sub‑elements) claims 3, 4 and 5, which are drawn almost verbatim from Wendt: claim 4's "blocking type [oscillator] producing indicating pulses" = Wendt's blocking oscillator 32/33 with retrace pulses 50; claim 5's indicating‑pulse‑producing means in the deflection output circuit = Wendt's deflecting coil 50 pickoff (and the '498's own auxiliary coil 101); claim 3's coincidence device = Wendt's phase detector bridge.

Combination 2: Combination 1 + Knick '290 (and/or Parker '817)

Claims 2, 10 and 11 add two things beyond the gating: (a) detection of sync/non‑sync (coincidence of sync pulses with locally derived indicating pulses) and (b) rendering the gate‑operating‑pulse source inoperative during async operation.

• For (a): the AFC/phase comparator of Wendt + Combination 1 already develops a voltage that is a direct function of the timing relationship between sync and the locally generated deflection wave — i.e., it is inherently a coincidence detector. Using an already‑present phase‑error voltage as a status signal is not an inventive act; it is reading a signal that exists and using it for its evident meaning. Parker '817 (an Avco TV‑sync AFC circuit, H04N5/12) is corroborative that AFC voltage generation for TV sync was routine.
• For (b): Knick '290 supplies the exact abstract control function — a biased rectifier responsive to a predetermined voltage level that renders the synchronizing/discharge‑initiating means inoperative. Substituting the sawtooth clipper of the '498 for Knick's biased rectifier, and the derived gate‑control pulses for Knick's discharge‑initiating impulses, is a substitution of one known threshold device for another with no change in function.

Motivation: the two‑state control is not merely a convenience; it solves an inherent deficiency of the gating approach itself. If the oscillator is free‑running out of lock, a gate that is normally closed and opened only by local pulses can never acquire lock, because the local pulses only exist at the wrong time. Any engineer who adopted the Volz gating arrangement would immediately confront the acquisition/resynchronization problem and the obvious remedy — detect loss of lock and temporarily bypass the gate. That the bypass should also disable the gate‑pulse generator is the natural corollary of the same decision (avoid two competing controls on the same gate tube), and Knick shows the threshold‑disabling mechanism for that purpose. This is "obvious to try" territory with a strong "predictable result" overlay.

Strength of Combination 2 as to claims 2, 10, 11, 13, 14, 15: high. As to claim 16 (mode control signals derived from the comparison means, i.e., AFC output → keyed/unkeyed mode), also high — that is precisely the Figure‑3 arrangement (noise‑immunizing tube 106 driven from AFC output resistor 94 via capacitor 107), and the tube 106 circuit (a tube biased near cutoff, driven into grid conduction by increased AC amplitude so average anode current falls and anode voltage rises) is a textbook noise/AGC‑type control stage, not a novel device.

Combination 3: Combination 2 + US 2,212,648 (RCA) for claim 9

Claim 9 (derive control signals from one deflection generator's output and use them to synchronize the other generator) is the weakest claim on the art cited. US 2,212,648 helps: it discloses interlocking two oscillators by AFC (a low‑frequency oscillator locked to the line, and a high‑frequency oscillator locked to that oscillator — i.e., one oscillator's output is the reference for the other's synchronization), and it discloses deriving line‑rate pulses from a higher‑frequency source by frequency division. That is the same master‑slave, cross‑coupled synchronization topology claimed in claim 9, applied to the horizontal/vertical pair. The '498's own spec supports the mapping by presenting the horizontal gating (including gate pulses 105) as the control that also governs the vertical gate (via tube 106 and resistors 109/111). Strength: moderate — the art coverage is thinner and would need verification of the Parker/Schnitzer/Campbell references for completeness.

Combination 4: for the dual‑sweep claim 8

Claim 8 duplicates the Combination‑2 apparatus in both the horizontal and vertical channels. The '498 itself says (specification, after Figure 2) that "the invention is useful with either or both of the horizontal and vertical deflection wave-generating apparatus," and that no modification is needed other than paralleling the existing stage. Duplication of a known circuit into a second, parallel channel of the same receiver is the clearest possible case of predictable variation. Strength: high, subject to the Note (i) drafting problem in claim 8's truncated text.

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5. Claim‑by‑claim disposition (on this record)

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6. The patentee's best counter‑arguments

1. Neither reference suggests the specific interlock. Volz does not disclose continuous conduction on loss of lock; Knick's biased rectifier disables its own initiating means but is not a sync‑versus‑no‑sync status detector. Under a strict pre‑KSR TSM analysis, there is no explicit "suggestion or motivation" in the references to combine the gating stage of the '498 with a lock‑status detector to produce a two‑state (gate‑open / gate‑closed) system. The Examiner had Volz in front of him and still allowed the case.
2. Teaching away. The specification itself describes the prior art as relying on long‑time‑constant AFC circuits for noise immunity, and states that such circuits were chosen because fast‑acting response was believed incompatible with noise immunity. If the art as a whole taught that noise immunity required slow/flywheel sync, one can argue it taught away from the claimed "fast acting" gated system.
3. Alleged synergistic result. Under the pre‑KSR "new or different function / synergistic result" line of authority still current in 1956 (see Great Atlantic & Pacific Tea Co. v. Supermarket Equipment Corp., 340 U.S. 147 (1950)), the patentee would argue that gating (fast) + coincidence‑responsive bypass (noise immune) yields a combined result neither reference produces — fast synchronization and noise immunity — that is different in kind from either.
4. Fast‑recovery implementation. The Figure 2 arrangement deliberately relies on increased conduction of the coincidence detector tube 61 to develop a more positive threshold voltage, with a minimum‑impedance indicating‑pulse source and a maximum‑value grid resistor 57. That polarity choice, and the stated reason for it, is an implementation insight not visible in the cited art — though it is captured in the specification rather than in the claim language, which limits its value.

Under KSR, arguments 1 and 2 are weak: the acquisition problem of a locally keyed gate is a recognized design consequence, not a hidden one, and "obvious to try" plus "predictable result" plus "same field, same problem, same assignee" (Volz, Wendt and the '498 are all RCA) heavily favors invalidity.

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7. Evidence that would be needed (none developed here)

The litigation review found no litigation, hence no developed record of secondary considerations. To rebut obviousness the patentee would need: evidence of long‑felt need for impulse‑noise immunity in 1940s–50s receivers; evidence the industry's alternative (flywheel/long‑time‑constant AFC) was understood to fail; evidence of unexpected results, copying, or licensing attributable to this system. Nothing in the record supplied supports any of these, and I will not attribute secondary‑consideration evidence that does not exist in the sources I reviewed.

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8. Bottom line and caveats

Bottom line. On the nine references cited in the patent itself, claims 3–7 and 12–15 read so closely on Wendt US 2,358,545 (keyed AFC, blocking oscillator, flyback indicating pulses) in combination with Volz US 2,685,033 (locally keyed gate, expressly for impulse‑noise immunity) that they would very likely be held obvious under § 103 as applied today. Claims 1, 2, 8, 10, 11 and 16 are somewhat stronger for the patentee because of the two‑state gate control and the disabling of the gate‑pulse source on loss of lock, but Knick US 2,265,290 supplies a threshold‑responsive device that renders a synchronizing element inoperative at a predetermined level, which supplies the missing element. Claim 9 has the thinnest art support. A pre‑KSR TSM defense is plausible; a post‑KSR defense is doubtful.

Caveats.

• I verified the substantive disclosures of US 2,685,033, US 2,358,545, US 2,212,648, US 2,265,290 and the bibliographic data of US 2,561,817. I did not verify the disclosures of US 2,141,343, US 2,207,048, US 2,240,420 or US 2,277,000 in this session; I have not attributed any specific teaching to them, and any mapping relying on them (notably for claim 9) is provisional.
• The inventor name "Poeh" for US 2,212,648 appears only in the OCR of the '498 reference list; I could not corroborate it and have not relied on it.
• Claims 2, 7, 8 and 11 are truncated in the retrieved text, and claims 2/11 recite a conductive/non‑conductive polarity that appears inverted against the specification. This analysis is based on the text as retrieved, without auto‑correction, and those anomalies should be resolved against the printed patent before any of this is relied on in a filing.
• This is a technical invalidity assessment, not legal advice, and no § 103 determination has ever been made by a court or the Office as to these claims.