US 2265290

I'll search for this specific patent number as requested.

Let me check for any USPTO litigation/PTAB records and CAFC 2026 docket activity for this patent number.

Search results for US patent 2265290

Important framing note: I searched for the literal identifier "2265290" against patent databases and 2026 litigation/docket material. I found no CAFC 2026 docket activity and no PTAB/IPR/litigation record for this patent — and none would be expected, because it is a 1941 patent that expired in 1958 (Google Patents lists legal status "Expired – Lifetime," anticipated expiration 1958‑12‑09). The string "2265290" does surface in searches, but only in unrelated contexts (a French patent document cited in US 5,010,903; a Brazilian STJ case number; a Florida corporate FEI number; a Chilean trademark publication CVE). Per your rule, I did not treat any of those as the patent.

The authoritative source used is the full text of the patent itself: https://patents.google.com/patent/[US2265290A](/patent/US2265290A)/en (fetched 2026‑09‑21), corroborated by https://FreePatentsOnline.com/2265290.html.

Bibliographic data

Uncertainty: The priority record is only partly legible — Google Patents lists the foreign priority document as "DE523457X 1937‑12‑30," which appears to be a mis‑mapping of the GB 523457 number rather than a true German application number. The actual German priority application number is not stated in the text I retrieved.

Abstract

There is no formal abstract. The patent predates the abstract requirement; the closest equivalent is the "Definitions"/summary passage and the objects paragraph. Plainly: the invention eliminates cumulative timing errors in television synchronizing pulses (ragged line edges, vertical picture jumping, loss of interlace) and holds the amplitude reached at the end of each saw‑tooth cycle constant. It uses a non‑self‑oscillatory (driven, one‑shot) circuit with two states — condenser charging and condenser discharging. A switching impulse starts the discharge; a derivative of that state (an impulse released once the voltage has reached a predetermined value) ends the discharge and restores charging. The discharge path is an electron discharge tube made conductive by the impulse and non‑conductive by the derived impulse.

Independent claims — plain-language overview

All three claims are independent (claim 3 is a further variant; see caveat below).

Claim 1 — generator with a "biased rectifier" shut‑off. A saw‑tooth generator with: (a) a first electron discharge tube (cathode, control grid, anode); (b) a condenser connected to that cathode and control grid, so the condenser voltage governs the tube's current; (c) a resistance element connected to the anode and cathode, whose voltage drop tracks the tube current; (d) means for charging the condenser; (e) means for discharging the condenser, including a second electron discharge tube; (f) means for turning that discharging means on; and (g) a biased rectifier that responds to a predetermined value of the voltage drop across the resistance element and is effectively coupled to the discharging means to turn it off. In the Fig. 2 embodiment this maps to condenser 53 / grid 42 of tube 43 for the sweep tube, cathode resistor 56 developing the drop, tube 35 as the discharge path, and diode 59 as the biased rectifier.

Claim 2 — the pulse‑generator version. Everything in claim 1, plus: a non‑self‑oscillating pulse generator that initiates pulses; means for applying those pulses to the discharging means to turn it on; and the biased rectifier is coupled to the generator so that its output pulses terminate the generator's pulses and thereby turn the discharging means off. This is the heart of the described operation — the sync pulse starts retrace, and the derived sense pulse ends it.

Claim 3 — further variant (text incomplete). The claim begins with the same "A saw‑to‑wave generator comprising in combination a first electron discharge tube having a cathode, a control grid and an anode, a condenser coupled to said cathode and said control grid for controlling the flow of current in said tube in accordance‑with voltages developed…" — and then the text as retrieved is truncated/garbled, so I cannot responsibly characterize the full scope of claim 3, including its characterizing elements. I am flagging this rather than inferring it. (The claim text in the Google Patents and FreePatentsOnline renderings both cut off at this point.)

Practitioner's note

The invention is straightforwardly described as a driven (triggered) sweep generator with amplitude self‑termination: the endpoint of each sweep is set by a sensed current threshold rather than by the sync pulse spacing alone, which is what makes the amplitudes constant when the driving pulse train frequency is constant. This is the classic "constant‑amplitude, sync‑initiated saw‑tooth" architecture later reflected in forward‑citing art such as US 2,448,070 and US 2,448,069 (Philco, "Saw‑tooth generator with automatic amplitude control") and US 2,492,018 (Philco, "Synchronizing system for sawtooth wave generators"). Google Patents lists 51 forward‑citing documents.

No CAFC 2026 docket entry, PTAB proceeding, or district‑court case involving US 2,265,290 was found. If you have a specific docket number you believe references this patent, give it to me and I will search that docket directly.

I'll research this. Let me search several litigation-focused sources for US patent 2265290.

Let me run additional targeted searches on litigation databases to be thorough.

Let me do a final check on the Unified Patents litigation portal and the patent's foreign counterparts.

Litigation Search Report — US Patent 2,265,290

Bottom line: No litigation is known involving US Patent No. 2,265,290.

I found no district court actions, CAFC appeals, ITC investigations, PTAB proceedings (IPR/PGR/CBM), or foreign counterpart suits involving this patent, in any of the sources searched.

Patent identified (to confirm the literal ID)

Sources searched and what they returned

• Google Patents / FreePatentsOnline: No litigation section, no "Cited By" litigation entries, only patent and trademark citations. The Google Patents "Cited By (51)" list is purely patent-document citations (e.g., US2448070, US2492018, US2750498) — not lawsuits.
• Unified Patents litigation portal, PACER/CAFC-oriented queries, Docket Alarm, CourtListener: No cases naming US 2,265,290. Searches on "2265290" and "2,265,290" returned zero patent-litigation hits.
• Foreign counterparts (GB 523457, FR 848178): No reported proceedings located.

Important disambiguation warning

A large share of "529 patent" search hits refer to a different patent: US 5,436,529 ("Control and protection circuit for electronic ballast," inventor Andrzej Bobel, Lighting Ballast Control LLC). That patent was litigated extensively — e.g., Lighting Ballast Control, LLC v. Philips Electronics North America Corp., No. 7:09-cv-00029 (N.D. Tex.), and Lighting Ballast Control, LLC v. Universal Lighting Technologies, Inc., with the Federal Circuit en banc decision in Lighting Ballast Control LLC v. Philips Electronics North America Corp., 744 F.3d 1272 (Fed. Cir. 2014) (vacated and remanded in light of Teva). That is US 5,436,529, not US 2,265,290, and must not be attributed to the patent you asked about.

Similarly, hits for "2265290" in trademark registries (Chilean Diario Oficial CVE 2265290; UK IPO trade mark journal entry for Symbol Technologies Ltd.; Indian trade mark 2265290 "Selact-34"), a Brazilian STJ docket (ARESP 2265290), and a Florida corporate filing (FEI 87-2265290) are unrelated non-patent identifiers.

Why this result is expected

US 2,265,290 issued in 1941 and its term expired in 1958, more than 65 years ago. It predates the modern patent-litigation reporting ecosystem (PACER electronic dockets begin in the late 1980s–1990s; CourtListener, Docket Alarm, and Unified Patents coverage is essentially contemporary). Any 1940s–1950s enforcement would be documented only in old print reporters or the USPTO's statutory § 290 notice records, which are not indexed in the databases searched. I did not locate any such record.

Caveats on confidence

• I can state with high confidence that no litigation is indexed in the searched modern databases.
• I cannot rule out unindexed historical litigation (1940s–1950s) captured only in paper records; I found no affirmative evidence of any, and I will not speculate.
• Per the operating rules, no patent numbers or identifiers above have been auto-corrected; US 2,265,290 is treated literally and distinctly from US 5,436,529.

I'll verify the absence of PTAB activity before writing the analysis.

Proceedings overview

Total AIA trial proceedings on file for US 2,265,290: 0 — no IPRs, no PGRs, no CBM reviews, no derivations, no instituted trials of any kind (breakdown: 0 active / 0 claims invalidated / 0 claims sustained / 0 settled / 0 institution denials). The reason is chronological rather than tactical: US 2,265,290 issued 1941-12-09 and expired 1958-12-09, roughly 54 years before the Leahy–Smith AIA created the IPR/PGR/CBM regimes (AIA enacted 2011-09-16; petitions available from 2012-09-16). The USPTO's own post-grant machinery did not exist during the patent's entire enforceable life — even ex parte reexamination (1980) and inter partes reexamination (1999) post-date its expiration by decades. Defensive bottom line: a demand letter citing US 2,265,290 is not a patent-enforcement threat at all. The patent has been dead since 1958-12-09; every one of its three claims lapsed with it. There is no PTAB record to arm a defendant because there is nothing left to invalidate — and, more usefully, no live cause of action to defend. The only modern significance of this document is as a § 102/§ 103 prior-art reference (publication date 1941-12-09), a role reflected in the 51 forward citations listed on the Google Patents page.

Proceedings

None. No AIA trial proceeding has ever been filed against US 2,265,290, and the "PTAB proceedings on file" block from the USPTO Open Data Portal returns nothing. There are therefore no proceeding numbers to enumerate, no panels to identify, no FWDs to quote, and no Federal Circuit appeals to trace. I am stating this as a verified negative rather than an inference: targeted searches for IPR/PGR/CBM activity, PTAB E2E entries, and Unified Patents-style third-party challenges returned no proceeding on this patent (Google Patents; PTAB E2E).

Two false positives to avoid, because they will burn a defendant who runs them into a brief:

1. "The '529 patent" shorthand in litigation and IPR papers. Multiple search hits refer to "the '529 patent" in Lighting Ballast Control LLC v. Universal Lighting Technologies (N.D. Tex. No. 7:09-cv-00029) and in PTAB filings. That is a 1990s lighting-ballast patent by a different inventor — not US 2,265,290. Shorthand claim-number collisions are common; the '529 in those documents has nothing to do with Knick's saw-tooth generator.
2. Google Patents' "Cited By (51)" list is a forward-citation list (later patents citing this one as prior art), not a list of validity challenges. It is not evidence of PTAB activity.

Non-AIA post-grant activity: I found no ex parte reexamination, inter partes reexamination, or reissue of US 2,265,290. Any such proceeding would in any event have had to occur before 1958-12-09, i.e., before those statutes existed. (Foreign counterparts FR848178A, published 1939-10-24, and GB523457A, published 1940-07-15, are likewise long expired.)

Strategic summary

Claim status. US 2,265,290 has 3 claims (as printed: "3 Claims"). Claims 1 and 2 are drawn to a saw-tooth wave generator and are set out in full in the patent text; claim 3 opens with the same "comprising in combination a first electron discharge tube having a cathode, a control grid and an anode, a condenser coupled to said cathode and said control grid for controlling the flow of current in said tube in accordance with voltages developed…" preamble, but the source text truncates mid-limitation. Per your instruction not to overstate, I will not characterize claim 3's full scope. What is unambiguous: all three claims expired by operation of law on 1958-12-09 — none canceled by the Board (the Board never touched them), all rendered unenforceable by expiration. So the CANCELED / SUSTAINED / UNTESTED framing collapses into a fourth category: EXPIRED — all three claims. There is no surviving claim set to design around.

Estoppel landscape. § 315(e)(2) estoppel is a nullity here: it attaches only to grounds a petitioner "raised or reasonably could have raised" in an IPR that resulted in a final written decision (or that was instituted and terminated). No IPR was ever instituted, so no party is estopped — by anyone. The corollary matters for your litigation posture: a defendant being pressed on this patent today faces no estoppel risk because there is no validity defense worth mounting, only a limitations/expiration defense. The § 286 six-year damages lookback cannot reach pre-1958 conduct that was lawful at the time, and there is no post-1958 infringing conduct by definition.

Pattern signals. No repeat-petitioner pattern (zero petitions), no patent-owner PTAB appellate practice by Fernseh GmbH / Robert Bosch Fernsehanlagen GmbH, and no defensive aggregator in the chain — Unified Patents and similar entities have never targeted this patent, which is consistent with their practice of challenging patents with live assertion value. The forward-citation traffic on the Google Patents page confirms the '290 patent's actual function in the ecosystem: it is a pre-war prior-art teaching about non-self-oscillatory saw-tooth generation and derivative-triggered discharge cut-off, cited during prosecution of later deflection-circuit patents, not a weapon.

Recommended next steps

• If you are a defendant: do not spend IPR budget — there is no proceeding to join, no live claim to invalidate, and nothing for the Board to review that would change your exposure. Your response to any assertion of US 2,265,290 is the expiration date: 1958-12-09, seventeen years from the 1941-12-09 grant, under the then-applicable term rules. The patent lapsed 68 years ago. A demand letter citing these claims should be answered with a short letter identifying the expiration date and requesting withdrawal, not with a Patent Owner Preliminary Response-adjacent filing.
• If you are contemplating a reexamination or IPR filing for defensive-cleanliness reasons: it is legally unnecessary. Institute on post-grant review is unavailable (this 1940 filing predates FITF by seven decades; PGR applies only to first-inventor-to-file patents), CBM review sunset on 2020-09-16, and IPR against a patent expired since 1958 would yield no enforceable benefit. The correct use of this reference is defensive prior art in someone else's case — asserted as a 1941-12-09 printed publication against a later patent claiming saw-tooth sweep generation, where its 51 forward citations, its GB and FR counterparts, and the Fig. 2 discharge-tube/diode cut-off teaching (described at the "Whentube 59 is rendered conductive, a negative impulse is applied to screen grid 31 of tube 35, blocking this tube immediately" passage) make it a credible § 102/§ 103 exhibit.
• Trial-stage milestones: not applicable — no institution decision deadline, no oral hearing, no statutory one-year FWD date, because no petition exists. Do not calendar any.
• No PTAB activity exists, and it never could have. That absence is not the usual "well-asserted patents eventually attract IPRs" signal — the patent was unenforceable for five decades before the first IPR was ever filed. Read it as confirmation that US 2,265,290 is a historical document, not an assertion asset.

Sources consulted: Google Patents US2265290A (authoritative full text, claims, and family data: US329568A filed 1940-04-13; DE priority 1937-12-30; grant 1941-12-09; anticipated expiration 1958-12-09); USPTO PTAB E2E and the USPTO Open Data Portal "PTAB proceedings on file" block (no AIA trial proceedings); web searches for IPR/PGR/CBM petitions against this patent (none found; the only "'529 patent" hits in PTAB and district-court documents concern an unrelated 1990s lighting-ballast patent).

I'll research the ownership chain for this patent using the sources specified.

Ownership Chain — US Patent 2,265,290

Tooling caveat stated up front: I do not have direct query access to assignmentcenter.uspto.gov / assignment.uspto.gov in this session; I worked from (a) the patent's own front-page recitals, (b) USPTO's published documentation of the Assignment Search database's coverage window, and (c) index-level searches for any reel/frame referencing this number. Where that limits the conclusion, I say so explicitly rather than inferring a chain. Per the operating rules, identifiers are taken literally and not auto-corrected.

Inventors

• The patent's front page reads: "Ulrich Knick, Berlin-Steglitz, Germany, assignor to Fernseh G. m. b. H., Berlin-Zehlendorf, Germany." The grant is thus already an assigned-inventor filing, not an inventor-owned filing. This is consistent with German practice of the period, and with Fernseh GmbH's position as the Bosch television subsidiary.
• Metadata discrepancy (flagged, not corrected): Google Patents' machine-readable inventor field renders the name "Knick Uirich" — clearly a transposition of "Ulrich Knick." The printed specification's rendering ("ULRICH KNICK") is authoritative. I did not auto-correct the metadata field, only noted the conflict.
• Name-coincidence caution (not a finding): A German instrumentation firm, Knick Elektronische Messgeräte GmbH & Co., was founded in Berlin in 1945 by a Ulrich Knick. I could not establish that this is the same person as the patent's inventor, and I am not asserting it. Flagging it only because a same-name Berlin instrument maker founded within 4 years of this filing is the kind of detail a chain-of-title analyst would want to rule out, not assume.
• Departure pattern: No evidence found of the inventor leaving Fernseh GmbH, and no evidence of any inventor-side assignment. One inventor, no joint‑inventor splits, no "all inventors departed within 12 months" pattern. There is nothing here of the pre‑fire‑sale signature.

Original assignee

Fernseh G.m.b.H., Berlin‑Zehlendorf, Germany (declined in the source material variously as "Fernseh G. m. b. H." and "Firm of Fernseh AG" on sibling patents).

• Primary line of business: Television equipment — camera and studio gear, film scanners/telecine, transmission and pickup-van systems. The corporate lineage traces to Fernseh AG, founded in Berlin on 3 July 1929 by John Logie Baird's Baird Television Ltd., Zeiss Ikon, D.S. Loewe, and Robert Bosch. Bosch bought out the other partners and took complete ownership in 1939, renaming it Fernseh GmbH (i.e., the assignee named on this patent is the Bosch-owned entity, which is why Google Patents attributes a "current assignee" of Robert Bosch Fernsehanlagen GmbH).
• Did they ship product embodying the claims? Yes, at the studio-equipment level. Fernseh built the world's first television outside-broadcast van (1934), used at the 1936 Berlin Olympics; during the war it was subordinated to the Luftfahrtministerium and worked on weapons-control systems; television development was banned by the Allied Control Council until 1949; from 1952 it supplied essentially everything needed to equip a television studio. This is a genuine operating company with real product, not a paper owner.
• Current status: Not operating under this name. The corporate path documented in German sources is: Fernseh GmbH → renamed Robert Bosch Fernsehanlagen GmbH (1972) → merged with Philips' studio-equipment business into Broadcast Television Systems (BTS), 1986 → Bosch exited to Philips (1993) → BTS sold to Thomson Multimedia (2001) → later Grass Valley, with the Darmstadt site effectively wound down. I found no bankruptcy or insolvency proceeding for the assignee at any point — this is a merger/divestiture trail, not a Chapter 7/11 fire‑sale trail.

Assignment timeline

No online assignment records exist for this patent in the USPTO Assignment Center. The Assignment Search database (assignment.uspto.gov / assignmentcenter.uspto.gov) contains all recorded patent assignment information only back to August 1980. Assignments recorded before 1 May 1957 are held by NARA, not in the online database (37 CFR 1.12(a)(2)). This patent issued 9 December 1941 and expired 9 December 1958 — it was already ~22 years expired before the database's coverage window opens. There is no plausible post‑1980 recordable event, and I found no reel/frame, conveyance type, or correspondent indexed for it.

What is documented, from the face of the patent and from the assignee's corporate history:

• Executed on or before 1940‑04‑13 (filing date) / recorded pre‑1957 (NARA custody) — Reel not available online (pre-1957 records are not in the online reel/frame database)

  • Conveyance: Assignment (inventor-to-company), recited on the patent face as "assignor to Fernseh G. m. b. H."
  • Assignor: Ulrich Knick
  • Assignee: Fernseh G.m.b.H.
  • Correspondent: Not available — the pre‑1957 NARA records do not carry the modern "correspondent of record" field, and no correspondent is printed on the patent.
  • Context: Standard inventor-to-employer assignment at filing. This is the only recorded transfer I can evidence.

• Not a recorded assignment, but the sole modern attribution on file — Google Patents lists "Current Assignee: Robert Bosch Fernsehanlagen GmbH." This is an entity-resolution inference from the 1972 corporate renaming of Fernseh GmbH, not a recorded assignment: no reel/frame, no conveyance type, no assignor, no correspondent. I am treating it as a name-change/naming artifact, not as a transfer link.

• ⚠ Open lead, explicitly unverified for this patent: In F.A.R. Liquidating Corporation v. Brownell (E.D. Pa., 1955) — an action under § 9(a) of the Trading with the Enemy Act, 50 U.S.C. App. § 9 — the plaintiff sought recovery of 111 US patents vested by the Alien Property Custodian under an assignment to F.A.R. Liquidating Corporation from Fernseh G.m.b.H., arising from a contract formed by cable offer in May 1941 and acceptance on 14 June 1941. The same original assignee is therefore documented as having moved a block of US patents to a US entity in June 1941 — eight months after this application was filed and six months before it issued. I could not determine whether US 2,265,290 was among those 111 patents, and I am not asserting that it was. This is the single highest-value item to check in the NARA pre‑1957 assignment records and in the FAR/Liquidating vesting schedules, because if it is in that block, the "original assignee still owns it" read is wrong.

Because the online record set is empty, any further chain reconstruction requires a manual NARA pull of the pre‑May‑1957 assignment records for patent 2,265,290.

Timeline diagram

timeline
    title Ownership of US 2265290
    1929 : Fernseh AG founded in Berlin
    1939 : Bosch takes full ownership
    1940 : US application filed by Knick
         : Assigned to Fernseh GmbH
    1941 : US patent 2265290 issued
    1958 : Patent term expires
    1972 : Renamed Bosch Fernsehanlagen
    1986 : Merged into BTS with Philips
    1993 : Bosch exits to Philips
    2001 : BTS sold to Thomson

NPE / troll-pattern signals

1. Shell-entity transfer — Not present. The only evidenced transfer is inventor → operating German manufacturer at filing. No "IP / Patents / Licensing / Holdings / Ventures" assignee appears anywhere in the record, and there is no recorded post-issuance transfer at all. No reel/frame supports a shell-entity step.

2. Known asserter in the chain — Not present. Neither Fernseh G.m.b.H. nor Robert Bosch Fernsehanlagen GmbH appears on RPX, Unified Patents, or any public NPE/asserter list for this patent. None of the enumerated asserters (Acacia, Marathon, IV, IPNav, Wi‑LAN, Mosaid/Conversant, Vringo, Pendrell, Innovatio, MPHJ, Lumen View, Round Rock, etc.) is in this chain.

3. Repeat correspondent across the chain — Unclear / no data. The pre‑1957 records that would carry a correspondent of record are in NARA custody and are not surfaced by the Assignment Center, so there is no correspondent name to test for recurrence. I will not manufacture one.

4. Cascading transfers — Not present. No recorded assignments at all post‑issuance, so no chained-LLC sequence within 24 months. The 1972/1986/1993/2001 events are corporate renamings and mergers of the same operating business, not chained single-purpose entities.

5. Pre-litigation transfer — Not present. No infringement suit naming this patent was found (see prior litigation section), and no assignment dated within 6 months of any suit. The patent expired in 1958.

6. Bankruptcy fire-sale — Not present. The assignee's lineage ends in merger and divestiture (Bosch → Philips → Thomson → Grass Valley), not in a Chapter 7/11 sale of the type seen with Kodak, Nortel, or Polaroid.

7. Privateering — Not present. No operating company is documented transferring this patent to an NPE to assert against competitors. The one adjacent transaction involving this assignee (the 1941 F.A.R. Liquidating contract) was a wartime US-government-vesting dispute, the opposite of privateering.

8. Defensive aggregator (anti-NPE) — Not present. No RPX, AST, LOT, Unified Patents, or OIN link in the chain.

Verdict

Insufficient data — the chain shows only the original inventor‑to‑employer assignment recited on the patent face ("Ulrich Knick … assignor to Fernseh G.m.b.H."), with no post-issuance assignment records available because the USPTO Assignment Center's coverage begins August 1980 and pre‑1 May 1957 records sit with NARA (37 CFR 1.12(a)(2)) — and this patent expired 9 December 1958. There is no shell LLC, no listed asserter, no correspondent recurrence, and no litigation to anchor an NPE finding, and the original assignee is a genuine German television manufacturer with documented products, whose lineage ended in M&A rather than bankruptcy. The one item that could revise this conclusion is whether US 2,265,290 was among the Fernseh‑GmbH patents assigned to F.A.R. Liquidating Corporation by the June 1941 contract at issue in F.A.R. Liquidating Corp. v. Brownell — unverified, and requiring a NARA pull.

Verify at: https://assignmentcenter.uspto.gov/ (search by patent number 2265290) and the legacy system at https://legacy-assignments.uspto.gov/assignments/?db=pat — note again that both begin at August 1980 and will return no hits for this patent. Pre‑1957 records: National Archives and Records Administration, per 37 CFR 1.12(a)(2).

I'll research this systematically. First let me verify the patent record and look specifically for its "References Cited" (backward/prior-art citations) as opposed to the forward "Cited By" list.

The critical finding: the Google Patents record for US 2,265,290 shows only a forward "Cited By (51)" list and a "Similar Documents" list — no backward "References Cited" (prior-art) field. Let me verify whether any prior-art citation list exists in other databases, and check the dates/content of the pre-1937 "Similar Documents."

Let me verify the specific pre-priority-date documents in the "Similar Documents" list, and check whether the GB/FR family members are indexed anywhere as citations.

I've hit my search-step budget, so I'll report what I verified and flag what I could not. One finding materially changes the framing of your request, so I'll lead with it.

⚠️ Critical framing correction: US 2,265,290 has no prior-art citation list

Your instruction — "look at each patent citation for 2265290" — rests on a premise that the record does not support. I verified this across both authoritative renderings:

• Google Patents (https://patents.google.com/patent/[US2265290A](/patent/US2265290A)/en) shows only a forward "Cited By (51)" table and a "Similar Documents" table. There is no "References Cited" / (56) U.S. Patent Documents field.
• FreePatentsOnline (https://FreePatentsOnline.com/2265290.html) likewise shows no examiner-citation list.

This is normal for a 1941 patent: pre‑1950s printed specifications frequently omit the examiner's citation list entirely, and the 1937–40 prosecution file wrapper is not reproduced in any of these databases. So there is no official "each patent citation" set to walk through, and I will not fabricate one.

What the record does give you is two lists, and they mean opposite things:

I verified the "Similar Documents" identification for this patent against the SumoBrain and FreePatentsOnline full texts (both return the identical specification), confirming the record I'm working from is the real US 2,265,290 and not a lookalike.

Part 1 — The "Cited By (51)" list: NOT §102 prior art

Every one of the 51 forward-citing documents post-dates US 2,265,290 (issued 1941‑12‑09). A reference cannot anticipate an earlier patent. None of these can anticipate any of claims 1–3 under §102, in any subsection. I list the most relevant ones only to document the patent's technical lineage (relevant to obviousness-of-later-art, not to validity of this patent):

§102 assessment: No anticipation. Earliest priority in this group is 1941‑07‑08 (US 2,436,808), i.e. after both the 1937‑12‑30 foreign priority date and the 1940‑04‑13 U.S. filing date of 2,265,290.

Part 2 — Genuine candidate prior art (from "Similar Documents," date-filtered)

The only references in the record that could conceivably qualify as §102 art are those in the "Similar Documents" list published before the 1937‑12‑30 priority date (which is also the effective §102(b) one-year-bar reference point, since the application is a refiling of Serial No. 248,483 filed 1938‑12‑30). Only two clear the date bar:

Other "Similar Documents" (US 2,165,815, pub. 1939‑07‑11, "Generator for television"; US 2,178,772, pub. 1939‑11‑07, "Two‑tube deflecting circuit"; US 2,188,653, pub. 1940‑01‑30, "Electronic oscillation generator"; US 2,212,933, pub. 1940‑08‑27, "Television system") all post-date the 1937‑12‑30 priority date and therefore cannot be §102(a) or §102(b) art against the priority-backed claims. They could only matter via an earlier-filed/§102(e)-style theory, which requires filing-date and full-text verification I was unable to complete (see caveats).

Claim-by-claim §102 assessment for A and B

Why I will not assert anticipation — and why that is the honest answer: For a reference to anticipate claim 1 it must disclose every element, including the two that give this patent its point of novelty: (i) a resistance element in the cathode/anode path whose voltage drop is sensed, and (ii) a biased rectifier responsive to a predetermined value of that drop and coupled to the discharge tube to shut it off. My searches returned titles and dates but not verified full texts for US 2,085,402 or US 2,097,334 — the queries surfaced unrelated later patents on cathode‑ray deflection rather than these two documents. On the record actually in front of me, I can confirm only the citation and the date; I cannot responsibly state that either discloses the biased-rectifier amplitude-termination element. Any §102 statement here would be speculation, so I'm declining to make one.

Claim 3 note (carried forward from the earlier section): the retrieved text of claim 3 is truncated/garbled and ends mid-limitation, so claim 3's full scope cannot be mapped against any reference. I flag this rather than infer it.

Part 3 — Family members (same invention — NOT prior art)

These share the 1937‑12‑30 priority (shown as "DE523457X" in the Google record) and are the same invention, so they are not prior art to US 2,265,290. Note the corroborating detail that GB 523457 published 1940‑07‑15 and FR 848178 published 1939‑10‑24, both after the U.S. filing — consistent with a common-priority family, not an earlier disclosure.

Your requested "USPTO database" search — result

I searched the specific literal identifier 2265290. The USPTO‑derived record (via Google Patents, which mirrors USPTO/EPO DOCDB data) returns one and only one U.S. patent: US 2,265,290 A, App. No. US 329,568, filed 1940‑04‑13, granted 1941‑12‑09, 3 claims, inventor Ulrich Knick, original assignee Fernseh GmbH. I did not substitute or merge any similar number. (For the avoidance of doubt, the earlier-generated sections already correctly distinguished this from US 5,436,529 and from non-patent uses of the string "2265290"; nothing here contradicts that.)

Confidence and caveats

• High confidence: US 2,265,290 has no backward "References Cited" list in the authoritative sources; the 51 "Cited By" documents are all later-dated and thus not §102 prior art; the family members are not prior art.
• Moderate confidence: that US 2,085,402 A and US 2,097,334 A are the only pre‑1937‑12‑30 items in the record's "Similar Documents" list — this depends on the completeness of that algorithmically-generated list, which is not an official examiner citation list and may omit actual prosecution references.
• Cannot state / would be fabrication: (a) any anticipation mapping of claims 1–3 onto US 2,085,402 or US 2,097,334 — I did not obtain or verify those full texts; (b) the full scope of claim 3; (c) whether any §102(e)-era earlier-filed art exists among the 1939–1940 publications, which needs filing-date verification I could not complete.
• Process note: I exhausted my search-step budget before I could retrieve the gazette/full-text of US 2,085,402 and US 2,097,334. If you want a definitive anticipation analysis, the next step is to pull those two documents' complete specifications (and the 1937–40 file wrapper via USPTO PatentCenter if available) and map their disclosures element-by-element against claim 1's "biased rectifier responsive to a predetermined value of the voltage drop" limitation.

Bottom line: There are no examiner-cited prior-art patents on the face of US 2,265,290 to enumerate, and none of the 51 forward citations can anticipate any claim. The only two date-qualifying candidate references in the record are US 2,085,402 A (1937‑06‑29) and US 2,097,334 A (1937‑10‑26); on the evidence I obtained I can neither confirm nor deny that they meet the biased-rectifier limitation, and I have not asserted anticipation for either.

I'll research the prior art available for this patent before analyzing obviousness.

Let me dig deeper into the specific prior-art references that are candidates for a §103 combination.

Obviousness Analysis — US 2,265,290 (Knick), 35 U.S.C. § 103

0. Framing, and two contradictions to flag up front

Contradiction 1 — dates. The system header for this task says "Today's date is 2026‑09‑21"; the task block says "Current Date: April 26, 2026." I am flagging rather than silently picking one. Nothing in the analysis below turns on the difference, because this is necessarily a retrospective/hypothetical validity study: US 2,265,290 issued 1941‑12‑09 and, per Google Patents, expired 1958‑12‑09 ("Expired – Lifetime"). § 103 analysis here is academic (historical validity, claim-scope study), not a live challenge.

Contradiction 2 — the operative pre-AIA evidentiary rule. This application was filed 1940‑04‑13. The 1952 Act's § 103 did not exist at issuance; the case would have been judged under R.S. 4886 / the "invention" requirement as construed in Cuno Engineering v. Automatic Devices (1941), and only later under Graham v. John Deere (1966) and KSR (2007). I apply pre-AIA § 102/§ 103 here because the AIA's § 103 applies only to applications filed on/after 2013‑03‑16. Any KSR‑style "predictable results" rationale below is offered as modern reconstruction, clearly labeled.

I do not repeat the claim-by-claim overview or the bibliographic table from the earlier sections; I build on them. One earlier section's caveat is reused verbatim: claim 3's text is truncated in both the Google Patents and FreePatentsOnline renderings, so I cannot verify its full scope.

1. What the "Prior Art" section of this page actually contains — an evidentiary gap

This matters more than usual, so I state it precisely:

Critical gap: the fetched HTML contains no "References Cited" section. Normally the printed patent face lists the examiner‑cited U.S. and foreign patents. That list is the single most important input to a real § 103 analysis, and it is missing. Any combination below is therefore built from (a) the page's Similar Documents list, (b) the applicant's own admissions in the specification, and (c) independent searches I ran for the same documents. The examiner‑of‑record's actual art has not been reviewed.

2. The eligible prior‑art universe, with dates (all identifiers treated literally)

Critically dates, before combinations: Knick's § 102(b) critical date is 1939‑04‑13 (U.S. filing 1940‑04‑13 minus one year); Knick's date of invention under pre‑AIA § 102(a)/(e) is the asserted German priority 1937‑12‑30.

Key finding § 3(a) — the Cited By list contains no prior art at all. The earliest priority date among the 51 forward citations is US 2,489,269 (1940‑05‑15) and US 2,591,677 (1940‑10‑11) — both after Knick's U.S. filing of 1940‑04‑13 and years after its 1937 invention date. Every other cited‑by document is 1941 or later. Therefore none of the 51 qualifies under § 102(a), (b), (e), or (g). The Philco "automatic amplitude control" patents (US 2,448,070 / US 2,448,069, filed 1944‑08‑30) and Philco's US 2,492,018 ("Synchronizing system for sawtooth wave generators," filed 1944‑11‑11), plus EMI's US 2,568,914 (filed 1946‑02‑23), are evidence that the industry later recognized and patented this exact problem — but they are not art.

Key finding § 3(b) — US 2,165,815 sits one day on the wrong side of Knick. Rhea's U.S. application was filed 1937‑12‑31; Knick's asserted German priority is 1937‑12‑30. If the German priority is valid and available under § 119, Rhea is not § 102(a) or § 102(e) art (its § 102(e) date is its U.S. filing date, not its convention date — In re Hilmer), and Rhea's 1939‑07‑11 issuance falls inside Knick's one‑year grace period, so it is not a § 102(b) bar either. Rhea is, on these dates, not prior art.

This is the pivot of the whole analysis. Earlier sections already flagged that the priority record is partly unreliable ("DE523457X" appears to be a mis‑mapping of GB 523,457). If the German priority cannot be substantiated, Knick's effective date drops to 1938‑12‑30 (parent Serial No. 248,483) or 1940‑04‑13 — and Rhea (filed 1937‑12‑31) becomes valid § 102(e)/§ 102(a) prior art, indeed the closest art in existence. Every conclusion below is therefore conditional on the priority date.

3. Element mapping — Claim 1 against US 2,165,815 (Rhea)

Using the claim-1 element breakdown from the earlier section (not repeated here). Rhea discloses (my bold for the operative differences):

The two genuine gaps for claim 1 are therefore: (i) the sensing element is a transformer winding rather than a resistor between anode and cathode; and (ii) the rectifier's role is expressed as initiating rather than terminating. Note, however, that Rhea's cycle does terminate at a predetermined point: "When the condenser is discharged the cycle is repeated." The Rhea circuit is a threshold‑sensing, self‑restarting condenser saw‑tooth generator — i.e., the same physical operation with the polarity of the control function described differently.

4. The § 103 combinations

Combination C1 — Rhea (US 2,165,815) alone, or Rhea + routine diode biasing → Claim 1

Rationale (predictable design choice): Rhea already discloses every functional step of claim 1. Replacing the transformer‑secondary sense winding with a resistor in the cathode lead (Knick's resistor 56) is the substitution of one conventional current‑sensing impedance for another, with no change in operating principle, and biasing a diode to fix a trigger level was ubiquitous (the reference to a "biased" rectifier is satisfied by any fixed bias source, as in the circuit's own voltage source 27). Under modern KSR rationales ("known technique," "obvious design choice," "predictable result"), claim 1 would be obvious. Caveat: Rhea's terminated‑vs‑initiated distinction is a real, if narrow, argument the patent owner could press.

Combination C2 — US 2,055,611 + US 2,165,815 → Claim 1

US 2,055,611 discloses a condenser (1) charged from a D.C. source through resistance 3, short‑circuited by the plate circuit of a pentode valve 2 used as "the combined oscillator and short‑circuiting device of a condenser," with the condenser voltage feeding the control grid of an amplifying pentode 13 whose plate circuit drives a deflecting coil 14 on a cathode‑ray tube. Rhea supplies the threshold‑sensing rectifier and the synchronized flyback. Motivation to combine: both are in the same field (cathode‑ray deflection/television), both address the same problem (linear saw‑tooth with sharp retrace), and US 2,055,611's discharge "valve" is expressly a substitute for more complicated short‑circuiting arrangements ("the device, however, has disadvantages of complicated connections which can not be easily adjusted") — an express invitation to improve the discharge‑control element. Result: claim 1's first tube + condenser + charging means + second‑tube discharge means + threshold‑detecting rectifier. Caveat: US 2,055,611's own period is set by an RC timing network (condenser 8 / resistance 9), i.e., it terminates the discharge on a time basis, not a sensed current basis — which is precisely Knick's stated contribution.

Combination C3 — US 2,085,402 + US 2,097,334 (both § 102(b)‑eligible) + Rhea's sync‑injection teaching → Claim 2

Both are pre‑critical‑date publications by a competing house (RCA, 1937‑06‑29) and an unnamed assignee (1937‑10‑26), the latter directed to "Control circuits for cathode ray devices," which is the exact environment of claim 1. Motivation: combining a known saw‑tooth/deflection oscillator with a known "control circuit for cathode ray devices" to inject synchronizing impulses is the whole point of the stated field. I cannot responsibly assert what these two references disclose — I retrieved only citation metadata for both. This combination is identified, not demonstrated.

Combination C4 — any of the above + US 2,165,815's synchronizing teaching → Claim 2's "non‑self‑oscillatory pulse generator"

Claim 2's added element is a driven (one‑shot) pulse generator plus means for applying its pulses to the discharge tube. Rhea expressly teaches synchronizing a deflection saw‑tooth generator with injected pulses ("Synchronizing impulses may be applied to the screen 4 of the valve 1"; and a triode embodiment "in which the synchronizing pulses are applied to the transformer winding 14"). The driven multivibrator was standard art by 1937. Separately, Knick's own specification supplies an admission that helps: the impulse generator is "not self‑oscillatory" and is externally excited by "an impulse generator (not shown) of any known type capable of producing a periodical train of rectangular impulses," and the synchronizing source is "any source (not shown) of square‑topped impulses." Under § 103, admissions in the specification that a claimed element is "any known type" are strong evidence that the element adds nothing inventive. Motivation to combine: using the incoming sync pulse to trigger the retrace of a driven sweep generator is the defining function of a television deflection generator; the combination yields the predictable result that the charging interval is fixed by sync spacing — which is exactly Knick's stated advantage.

Combination C5 — Claim 3

The retrieved text of claim 3 begins with the identical preamble ("A saw‑tooth wave generator comprising in combination a first electron discharge tube having a cathode, a control grid and an anode, a condenser coupled to said cathode and said control grid for controlling the flow of current in said tube in accordance‑with voltages developed…") and then truncates. Based on the fragment, claim 3 appears to be a further variant of the same combination and would fall to the same reasoning as claims 1–2. I decline to state the scope of claim 3 or to assert its obviousness on the record available. The full text should be obtained from the USPTO patent PDF.

5. The single most important obstacle to any rejection: the date

This is why the earlier section's warning about the malformed "DE523457X" priority record is not a bibliographic curiosity — the entire § 103 outcome of this patent turns on it.

6. Counterarguments the patent owner would raise

1. Opposite function. In Rhea the rectifier starts the discharge; in Knick the rectifier stops it. Whether a given reference teaches "initiating" vs. "terminating" the same transition has been treated as a genuine difference where the reference's circuit depends on the transition running to completion (here, on the condenser reaching full discharge). A pre‑KSR tribunal applying Cuno's "flash of genius" language could readily find the re‑assignment of function non‑obvious.
2. Amplitude constancy as the stated object. Knick's claimed advantage — amplitude held constant because charging time is fixed by sync spacing and discharge time is fixed by a predetermined sensed level — is a different object from Rhea's (linearity + fewest components + economy). Different stated objects can defeat a "same problem" motivation (cf. In re Ratti).
3. No verified art for the terminating rectifier. I found nothing in the date‑qualified set that terminates a discharge in response to a sensed current‑derived voltage drop. The closest disclosure of that idea I encountered is EMI's US 2,568,914 ("when the condensers are discharged to a predetermined potential the diode is rendered conducting so as to prevent further discharge… Since the point at which the diode is rendered conducting is determined by the bias potential applied to its anode, the condensers can be arranged to be discharged to a constant potential") — but that is a forward citation of Knick (filed 1946), i.e., later art that arguably adopts Knick's teaching. Its near‑verbatim correspondence to Knick's object cuts for the patent's inventive contribution, not against it.
4. Secondary considerations: unavailable. I located no evidence of commercial success, copying, licensing, or long‑felt need, and no Fernseh enforcement record (consistent with the earlier litigation section).

7. Bottom line

• No reference in the page's "Prior Art" section — neither the 51 Cited‑By documents nor any of the Similar Documents dated after 1939 — is available as prior art. The Cited‑By list is entirely forward art (earliest 1940‑05‑15).
• Claim 1 is prima facie obvious over US 2,165,815 (Rhea) alone or in view of routine diode biasing — if Rhea is prior art. Rhea discloses a condenser‑coupled sweep tube, D.C. charging means, a second electron‑discharge tube (diode 19) as the condenser discharge path, and a rectifier that responds to a predetermined sensed voltage to control that discharge.
• Claim 2 is prima facie obvious over Rhea's combination with a driven (non‑self‑oscillatory) multivibrator, supported by Rhea's express sync‑injection teaching plus Knick's own "any known type" admission.
• But Rhea's U.S. filing (1937‑12‑31) postdates Knick's asserted German priority (1937‑12‑30) by one day, so on the face of the record Rhea is not § 102(a)/(e) art, and its 1939 issuance falls inside the § 102(b) grace period. If the priority is valid, the Rhea‑based rejections collapse and the analysis must instead rest on US 2,085,402, US 2,097,334 and US 2,055,611, whose full disclosures I was unable to retrieve before exhausting my search budget.
• Claim 3 remains unanalyzable on the retrieved text (truncation).

Highest‑value next steps: (1) obtain the owner's German priority document to fix the date — the entire analysis hinges on it; (2) retrieve the printed "References Cited" list from the USPTO PDF (absent from the fetched page); (3) pull full texts of US 2,085,402, US 2,097,334, US 2,178,772, US 2,212,933 and US 2,188,653 to check their U.S. filing dates for § 102(e).

Sources: https://patents.google.com/patent/[US2265290A](/patent/US2265290A)/en (fetched 2026‑09‑21) · https://SumoBrain.com/patents/us/System-synchronizing-television-transmissions/[2265290](/patent/2265290).html · US 2,165,815 via https://SumoBrain.com/patents/us/Generator-television/[2165815](/patent/2165815).html · GB 523,476 abstract via The Wireless Engineer, Feb. 1941, https://www.worldradiohistory.com/hd2/IDX-UK/Technology/Technology-All-Eras/Archive-Experimental-Wireless-IDX/IDX/40s/Wireless-Engineer-1941-02-IDX-49.pdf · US 2,055,611 via https://patents.google.com/patent/[US2055611A](/patent/US2055611A)/en · US 2,568,914 via https://patentimages.storage.googleapis.com/67/fa/d5/7421eaba5848c0/US2568914.pdf · US 2,085,402 / US 2,097,334 dates from Google Patents citation records (metadata only).

This is a technical analysis of the printed record, not legal advice.