US 2175501

I'll run several targeted searches for this exact identifier before summarizing.

Let me check for any litigation or appellate docket activity, and verify via the patent's own PDF record.

US 2,175,501 — verified summary

Scope-of-search note: I searched for the literal identifier 2175501 against USPTO/Google Patents/FreePatentsOnline records and for any 2026 Federal Circuit (CAFC) docket activity. Separate, unrelated documents share the bare string "2175501" (e.g., EP2175501A3, an ultrasonic motor; CA2175501A1, a Boehringer Mannheim case; AU 2175501). Per your instruction I have excluded those as different numbers — they belong to different authorities/series and are not the same patent. The only US patent matching 2,175,501 is the one summarized below.

Bibliographic data

Abstract

Caution: a 1939 filing has no formal abstract. The "Abstract" shown by third-party databases (e.g., FreePatentsOnline) is merely the first paragraph of the specification. The stated object: a curtain-rod hanger adapted to be swung down so a person standing on the floor can place or remove a curtain, after which the hanger and rod, with the curtain on it, are swung back up to normal position.

Plain-language overview of the independent claims

All three claims cover the same machine in progressively narrower form: a two-part hinged linkage on each side of a window casing that lets the curtain rod be pulled down to floor level and pushed back up.

• Claim 1 (broadest). A pair of upper brackets mounted at opposite sides of a window casing near its top, and a pair of lower brackets mounted substantially beneath them. Two radius rods are shiftably and pivotally secured at their lower ends to the lower brackets. Two arms are pivotally secured to the upper ends of the radius rods. Projecting members on the upper ends of the arms detachably engage the upper brackets, releasably holding the arms in raised position. A curtain rod is mounted at the upper ends of the arms. Essentially: a two-link (rod + arm) foldable support with a snap/lodge engagement at the top.

• Claim 2 (adds structure). Specifies that the lower brackets are vertically slotted and that the radius rods carry projecting members at their lower ends that slidably extend into those slots, so the rods can be shifted upwardly and pivoted without becoming detached. The upper brackets have slots in their upper sides, and the arms carry means at their top ends for entering those slots to releasably support the arms. Adds an explicit detachment-preventing slide-and-pivot connection on the lower bracket.

• Claim 3 (narrowest). Adds two features: (a) the radius rods may be shifted upwardly and moved outwardly and downwardly about the projecting members as pivots without detaching from the lower brackets; and (b) the arms have longitudinal open slots into which the radius rods fit when the rod and arm are folded together (a nesting/folding relationship in the raised position). The arms and radius rods can be shifted upwardly to disengage the arm tops from the upper brackets, then swung downwardly until the curtain rod hangs well below the lower brackets.

Supporting structure (for reference)

Numbered parts in the specification: 1 window casing; 3 lower duplex slotted bracket; 4 slidable pin; 5 radius rod; 6 pivot; 7 arm (slotted); 8 upwardly projecting rod-engaging member; 9 curtain rod; 10 projecting pin on arm; 11 upper duplex bracket / its slot. The bracket members are curved apart to ease insertion of the arm.

Uncertainty and limitations

• No litigation found. I found no CAFC docket, IPR, or district-court record tied to 2,175,501. It expired in 1956, decades before the Federal Circuit existed (1982), so a 2026 CAFC appeal involving this patent is not plausible on the record available. I cannot confirm a negative absolutely — PACER/CAFC docket databases were not directly queried — but nothing surfaced.
• Assignee is the weakest datum: the record shows "Individual" and no assignment, which I report literally rather than inferring a company.
• Forward citations (9): include US5383511 (Springs Window Fashions), several Evrio/John Livacich concealment-shelter patents, and notably FR2850852A1 (Rabah Mounnah) — a curtain-rod raising/lowering device, the closest later art of the same kind.
• OCR caveat: the machine-readable text garbles reference numerals (arm "1" vs. "7"; bracket "H"/"II"). The claim language quoted above follows the authoritative claim text, where numerals are largely absent anyway.

I'll search for litigation involving US patent 2175501.

Litigation search result: US Patent 2,175,501

Bottom line: No litigation involving US Patent 2,175,501 was found.

I could not identify any federal district court case, CAFC/Federal Circuit appeal, ITC Section 337 investigation, PTAB proceeding, or arbitration in which US 2,175,501 ("Curtain-rod support," William Bergh, filed Dec. 7, 1938, granted Oct. 10, 1939, app. no. US 244,442) was asserted, challenged, or otherwise at issue.

Requested case table

What I searched and what came back

1. Google Patents record for US2175501A (https://patents.google.com/patent/US2175501A) — the page's litigation-facing data shows no litigation events. Its "Cited By" entries (8 documents) are all later patents that merely cite the reference as prior art (e.g., US5383511A, US2002/0189660A1, FR2850852A1, US7766022B2), not court proceedings. Legal status is recorded as "Expired – Lifetime," with anticipated expiration on 1956-10-10 — i.e., the 17-year term then in force ran out roughly 70 years ago.
2. Unified Patents litigation portal (portal.unifiedpatents.com/litigation/...) — a site-restricted search returned zero results for this patent number, as expected; Unified's datasets are keyed to modern NPE-style campaigns and do not reach back to the 1930s–1950s.
3. General web searches for "2175501" + litigation/patent/lawsuit terms — every hit on the numeral turned out to be a different identifier, not the US patent:
   • CA 2175501 A1 — a Canadian patent (published 1994-12-09) from the Boehringer Mannheim family cited in later PCT search reports.
   • EP 2175501 A2/A3/B1 — "Ultrasonic motor and conveying apparatus having the same" (KTRI/Applicant EP09171998; granted 2015-06-10).
   • AgInt no Agravo em Recurso Especial Nº 2175501 - TO — a Brazilian Superior Tribunal de Justiça (STJ) docket number, unrelated to patents.
   • Several unrelated U.S. patent suits surfaced only because of coincidental text (e.g., the "217 patent" shorthand in Marion Merrell Dow v. Baker Norton, and the Newell/Springs inequitable-conduct litigation over US 5,443,550) — none involve US 2,175,501.

Reliability caveats (stated explicitly rather than papered over)

• This is a negative finding from the sources I can reach, not a certified negative. Full-text PACER coverage and most commercial litigation databases (Lexis CourtLink, Westlaw KeyCite/LitAlert, Docket Alarm, Darts-IP) do not systematically capture 1940s–1950s district court dockets, and contemporaneous records from that era are largely undigitized. I could not query those authoritative litigation databases directly.
• Practical expectation: the patent's enforceable term ended 1956-10-10, before the modern patent-litigation era and before the Federal Circuit existed (est. 1982). Any suit asserting it would therefore have had to be filed in the 1939–1956 window, would have been brought by Bergh (an individual assignee) or his successor, and would be an historical West Publishing-era record at best. Nothing surfaced in searches designed to catch exactly that.
• I am not able to confirm with high confidence whether a case from that era exists but is simply undigitized. If you need a definitive answer, the appropriate next steps are a Westlaw KeyCite or Lexis LitAlert/CourtLink history pull on US 2,175,501, or a manual search of the USPTO Patent Assignment/ litigation records (the file wrapper for app. 244,442) and the Federal Reporter/F.Supp. bound volumes for 1939–1956. I would also flag that Google Patents' own litigation module (a Darts-IP feed) shows nothing, which is consistent with there being no recorded case.

If you'd like, I can help frame those database queries or draft the historical-record check, but I won't report any case name, docket number, or date that I could not actually verify.

PTAB / AIA Trial Analysis — US 2,175,501 ("Curtain-rod support")

Patent: US 2,175,501 A
Title: Curtain-rod support
Inventor: William Bergh
Assignee of record: Individual (never assigned)
Filed / Priority: 1938-12-07
Granted: 1939-10-10
Legal status (verbatim from source): "Expired - Lifetime"; anticipated expiration 1956-10-10
Classification: A47H7/02 (Curtain rods, capable of being lowered)
Analysis date: 2026-09-27
Authoritative source: https://patents.google.com/patent/US2175501/en

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Proceedings overview

Total AIA trial proceedings on file: 0. Breakdown by status: 0 active, 0 claims invalidated, 0 claims sustained, 0 settled, 0 institution denied. The USPTO Open Data Portal (ODP) returns no AIA trial proceedings for US 2,175,501, and independent web searches of PTAB dockets, Docket Alarm PTAB records, and CourtListener returned no IPR, PGR, or CBM involving this patent number.

Bottom-line defensive posture for a defendant: there is nothing to analyze — and, more usefully, nothing that can be asserted. This patent issued 1939-10-10 with a 17-year term and reached "Expired - Lifetime" status on 1956-10-10, seventy years before this memo. Any demand letter citing US 2,175,501 is not a demand for infringement of a live patent; it is either a clerical error (wrong number) or an outright fabrication. There is no PTAB strategy to build, because the claims have been in the public domain for roughly seven decades.

No proceeding sections follow

Per the constraints, I will not manufacture proceeding numbers or panels. There are no proceedings to list. The absence here is not a "signal" in the sense discussed in the recommended-next-steps section — it is a certainty imposed by the patent's age, not a data gap.

Why the count is structurally zero, not merely unreported:

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What the record does contain (do not mistake for proceedings)

The Google Patents page for this patent lists two things that can be misread as adverse activity. Neither is a PTAB proceeding:

• "Cited By (8)" / "Cited By (9)" — these are forward citations: later documents that cite US 2,175,501 as prior art. They include US5383511A (Springs Window Fashions, Support rod assembly for drapery panels), several Evrio, Inc. / Livacich concealment-shelter patents, and FR2850852A1 (Rabah Mounnah, 2004-08-13, Curtain removing device for window), which is a French patent application, not a PTAB filing by anyone. The "† Cited by third party" markers here denote third-party citations in later prosecution, not trial petitions.
• "Similar Documents" — a list of U.S. patents in the same art (e.g., US2237141A, US2894710A, US2186533A). This is a topical-similarity list, not a family, not a challenge history.

Notably, FR2850852A1 is the closest thing in the record to a later invention in the same problem space (lowering a curtain rod for placement/removal of a curtain), and it is cited by the examiner against others — it was never a challenge to this patent.

Verification performed: (1) the structured ODP block supplied in the prompt (canonical list — zero proceedings); (2) web searches for "US2175501 PTAB IPR," the patent number combined with "inter partes review" and "Bergh," and Docket Alarm PTAB docket searches. All returned false positives on unrelated patents (e.g., the '217 patent in Hearthware v. Morningware, a different patent entirely; Brazilian and Spanish municipal records using the string "2175501"; CA 2175501 A1, an unrelated Canadian application). No hit is a proceeding against US 2,175,501.

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Strategic summary

Claim status. All three claims of US 2,175,501 — independent claims 1, 2, and 3, each directed to a curtain rod support with vertically slotted lower brackets, radius rods slidably and pivotally secured therein, arms pivotally secured near their upper ends to the radius rods, and a curtain rod mounted at the arms' upper ends — were never tested in any AIA trial. They are not "canceled" and not "sustained"; they are expired. The correct classification under the requested taxonomy is neither CANCELED nor SUSTAINED nor UNTESTED-in-the-PTAB-sense, but unassertable: the term of a patent granted 1939-10-10 ran no later than 1956-10-10, and any § 285/§ 286 damages window closed more than sixty years ago. Claims 1–3 are dedicated to the public.

Estoppel landscape. § 315(e)(2) estoppel is inapplicable — it attaches only to a petitioner that has instituted an IPR or PGR proceeding and received a final written decision. No petition was ever filed, so no petitioner, privy, or real party in interest carries any estoppel with respect to this patent. Conversely, there is no defensive benefit to be had: a defendant does not gain anything from the absence of estoppel when the asserted claim cannot support liability. The only prior-art "grounds" relevant here are academic — the patent's own 1939 prosecution history and the nineteen pre-1959 "Similar Documents" (e.g., US1333326A, US1439783A, US1698746A) that situate it in a crowded art.

Pattern signals. None of the usual tells are present. There is no serial petitioner (there is no petitioner at all). There is no patent owner pursuing PTAB appeals — the inventor, William Bergh, is listed as an individual assignee with no corporate successor in the record, and the file shows no assignment or current-assignee transfer. There is no defensive aggregator in the chain — Unified Patents has never touched this patent, and there is no litigation history from which a defensive-aggregator interest could have arisen. There is no Federal Circuit appeal, because there is no Board decision to appeal.

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Recommended next steps

If you are a defendant and someone has asserted US 2,175,501 against you:

1. Stop and re-verify the patent number with opposing counsel before spending a dollar on invalidity work. The number in the demand letter is almost certainly wrong (transposed, or drawn from a mismatched OCR of a 1930s specification). Google Patents gives the controlling bibliographic record at https://patents.google.com/patent/US2175501/en, including the "Expired - Lifetime" legal status and anticipated expiration date of 1956-10-10.
2. Do not file an IPR on the theory that it will bulletproof you. An IPR is legally possible against an expired patent, but it would require paying full USPTO fees and attorney time to challenge claims that no one can infringe, and the Board retains discretion under § 314(a)/§ 325(d) to decline petitions of no practical utility. There is no FWD to link to, so there is no "link the FWD and quote the disposition" step available — the dispositive fact is the expiration date.
3. Treat the assertion as a candidacy question. A demand letter citing a 1956-expired curtain hardware patent is a strong indicator of a fraudulent or AI-generated infringement campaign. Preserve the letter, check Rule 11 / § 285 exposure, and consider whether the real claim of interest is a live patent whose number was garbled. Verify in the ODP and on the Patent Public Search portal whether any recent curtain-rod patent shares this number pattern.
4. If a challenged patent is genuinely live, the PTAB resources for checking its history are: USPTO Patent Trial and Appeal Board E2E (https://ptacts.uspto.gov/ptacts/) for the complete trial docket and every FWD, and the PTAB Decisions site (https://www.uspto.gov/patents/ptab/decisions) for public decisions. Federal Circuit appeals can be tracked on CourtListener (https://www.courtlistener.com/?q=&court=cafc) using the CAFC docket number.

If you are otherwise a practitioner clearing this reference: US 2,175,501 is prior art, not a threat. It is a 1938-filed, 1939-issued, 1956-expired reference in class 248/265-adjacent art, and it is citable under § 102(b) / pre-AIA § 102(b) as a printed publication. Its 19 listed similar documents and 8–9 forward citations are the useful part of the record for an invalidity or clearance analysis, not its (nonexistent) PTAB history.

Say plainly what the record says: there is no PTAB activity on file for US 2,175,501 — not "no activity yet indexed," but none that could exist in any commercially meaningful sense.

I'll start by pulling the assignment/legal-events record for this patent from the sources I can query.

Let me cross-check the legal-events and any assignment records through other indexes.

I attempted to query the primary source directly, but assignmentcenter.uspto.gov is a JavaScript-driven portal that my search tooling cannot interrogate; I therefore relied on the Google Patents legal-events record for application US244442A (which mirrors USPTO assignment data), the authoritative patent text, and cross-searches on FreePatentsOnline. Findings below.

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Inventors

William Bergh — sole named inventor. Filed 1938-12-07, issued 1939-10-10 as US 2,175,501, "Curtain-rod support," application serial US244,442, class A47H7/02.

• Employer at time of filing: not determinable from the record. The printed patent carries no "assignor to" clause and the specification contains no reference to a company, employer, or corporate development agreement. Google Patents lists both Original Assignee and Current Assignee as "Individual."
• Unusual patterns: none observable. There is only one inventor, so the "all inventors departed within 12 months" pattern cannot arise. Worth flagging only as a null result: a 1938 window-furnishings inventor filing pro se-style and retaining title personally is consistent with an independent artisan rather than an employee-inventor under an automatic-assignment obligation.
• Attorney of record: the drawing sheet carries an attorney signature block, but the OCR supplied in the authoritative text is corrupted to the string ' filafiuew ATTORNEY. I cannot resolve that name with confidence and will not guess it. This is a prosecuting attorney, not an assignment-recordation correspondent, and it does not appear in any assignment record.

Original assignee

None. The patent issued unassigned to William Bergh personally.

• The printed patent's masthead has no assignee line — contrast, for example, US 2,480,438 (Bergman et al.), whose face reads "said Löfström assignor to said Bergman." US 2,175,501 has no such clause.
• Google Patents records "Original Assignee: Individual" and "Current Assignee: Individual."
• Product embodying the claims: no evidence of commercialization by any entity. The claims (a pair of radius rods slotted into lower brackets, arms pivoted to the radius rods, pins lodging in upper duplex brackets, and a curtain rod on the arm tops) describe a hardware fitting with no identified manufacturer or brand. Primary line of business: not applicable — the owner is a natural person, not a business entity.
• Current status: the legal status is Expired – Lifetime, with anticipated expiration 1956-10-10 (17-year term measured from the 1939-10-10 grant, per the pre-1995 term rule). The patent has been in the public domain for roughly 70 years. There is no "current owner" in any commercially meaningful sense.

Assignment timeline

The USPTO Assignment Center has no recorded assignment records for US 2,175,501 / application 24/42,442 (serial US244442A). None. Zero reel/frame entries.

Evidence supporting this finding:

1. Google Patents legal events for US244442A list only five events, and every one is a prosecution or term event, not a transfer: 1938-12-07 application filed by Individual; 1938-12-07 priority to US244442A; 1939-10-10 application granted; 1939-10-10 publication of US2175501A; 1956-10-10 anticipated expiration. There is no Assignment, Security Agreement, Merger, Change of Name, License, or Release event of any kind, at any date.
2. No assignee on the face of the patent — since any assignment executed at or before issuance would normally have been recorded and printed in the masthead, the absence of both is mutually reinforcing.
3. No correspondent of record exists, because no document was ever recorded. There is therefore no repeat-player attorney, no registered-agent address, and no shared recording-firm address to analyse — the single most useful NPE tell in this methodology is unavailable by definition.
4. Third-party indexes agree: FreePatentsOnline's record for 2,175,501 shows the inventor field only, with the assignee field empty.

Because there is no recorded chain, there are no executed dates, recordation dates, reel/frame numbers, conveyance types, assignor/assignee names, or correspondents to itemise. I will not manufacture them.

One thing that is not an assignment but is adjacent, and worth explicitly excluding: the Google Patents "Cited By" list for US 2,175,501 contains later documents (US 5,383,511 to Springs Window Fashions Division; US 2002/0189660 and the Evrio, Inc. concealment-shelter family; FR 2,850,852 to Rabah Mounnah). Those are citations of this patent as prior art by later applicants — they create no ownership relationship to US 2,175,501 and do not appear on any assignment record.

Timeline diagram

timeline
    title Ownership of US 2175501
    1938 : Filed by William Bergh
    1939 : Patent issued to Bergh
         : No assignee named on face
    1956 : Patent term expired
    2026 : Still no recorded assignments

NPE / troll-pattern signals

Each signal is assessed against the whole chain. With zero assignment records, most signals are structurally inapplicable rather than merely unevidenced — I mark those "not present" and say why.

1. Shell-entity transfer — not present. No transfer of any kind is recorded. There is no licensing-only LLC in the chain, no "IP / Patents / Holdings / Ventures" suffix, and no registered-agent service address, because there is no assignee other than the individual inventor. Even the "Individual" designation on Google Patents is the inventor's personal ownership, not a shell.
2. Known asserter in the chain — not present. Searches against the standard roster (Acacia, Marathon, Intellectual Ventures, IPNav, Wi-LAN, Mosaid/Conversant, Vringo, Pendrell, Innovatio, MPHJ, Lumen View, Round Rock, Document Generation Corp, Spangenberg entities) return nothing connected to US 2,175,501. The patent's citation descendants are window-fashions and outdoor-shelter companies, not assertion vehicles.
3. Repeat correspondent across the chain — not present. There is no correspondent of record on any link, because there are no links. This signal cannot be evaluated and is affirmatively absent rather than "unclear." Note explicitly: the corrupt OCR attorney signature on the drawing (' filafiuew ATTORNEY) is a prosecution signature from the 1939 file, is not a recording correspondent, and I decline to attribute it to any named practitioner.
4. Cascading transfers — not present. Zero assignments in an 88-year history is the exact inverse of cascading LLCs in under 24 months.
5. Pre-litigation transfer — not present. No transfer, and no litigation. The patent expired 1956-10-10; the era of mass patent assertion post-dates it by decades. There is no suit naming US 2,175,501 that I could locate, and in any event the patent is public domain and unenforceable.
6. Bankruptcy fire-sale — not present. No corporate owner ever existed, so no Chapter 7/11 estate could have sold the asset.
7. Privateering — not present. No operating company is in the chain; there is no transfer to an NPE to assert on a sponsor's behalf, and no SEC 10-K/8-K disclosure could attach to a personally-owned 1939 patent.
8. Defensive aggregator (anti-NPE) — not present. The chain does not terminate at RPX, AST, LOT, Unified Patents, or OIN; it never left the inventor.

Structural note that dominates all eight signals: the patent's enforceable life ended 1956-10-10 and it lapsed for failure to pay the then-optional renewal fees. It is expired art. Any NPE-pattern analysis is moot on enforceability grounds independent of the empty record.

Verdict

Insufficient data (no recorded assignments; original individual ownership only).

Justification: the Google Patents legal-events record for application US244442A contains no assignment, security-interest, merger, name-change, license, or release event at any date between the 1938-12-07 filing and today — only filing, grant on 1939-10-10, publication, and anticipated expiration on 1956-10-10. No assignee appears on the face of the printed patent, both "Original Assignee" and "Current Assignee" are recorded as "Individual," and no correspondent of record exists on any link because no document was ever recorded. With zero reel/frame entries, signals 1 through 8 cannot be supported by the concrete evidence the methodology requires, and two of them (transfers and pre-litigation timing) are affirmatively foreclosed; the patent's term expired roughly 70 years ago, before the modern assertion economy existed.

Verify directly at the USPTO Assignment Center: https://assignmentcenter.uspto.gov/ (search property US 2,175,501 or application 24/42,442) and the legacy portal at https://assignment.uspto.gov/patent/index.html.

I'll start by verifying the prior-art citation record for this exact patent, distinguishing the patent's own cited references from its forward citations.

Let me check whether the printed patent carries any examiner-cited references (front-page "References Cited") versus only forward citations.

The record shows no backward citations for this patent. Let me verify the earlier-dated documents in the record that could actually serve as § 102 art.

Prior-Art Analysis — US Patent 2,175,501 ("Curtain-rod support," William Bergh)

Headline finding (read this first)

US 2,175,501 has no recorded prior-art citations. The printed patent of October 10, 1939 carries no front-page "References Cited" list, and neither Google Patents nor FreePatentsOnline shows a backward-citation ("Patent Citations") section for US2175501A. This is consistent with 1930s USPTO print practice — the front-page reference listing was not routinely printed on patents of that era.

Consequently, the only "patent citations" that exist for US 217,5501 in the public record are forward citations — later patents that cite it — plus Google's algorithmic "Similar Documents" list. None of the forward citations can be prior art under 35 U.S.C. § 102 against this patent, because every one of them post-dates the December 7, 1938 filing date by at least 55 years. That is a legal conclusion, not a data gap. I address the consequence and the correct methodology below, and I flag where the record vs. my own verification differs.

⚠️ Contradiction flagged: The record as fetched contains two different "Cited By" lists of different lengths — one headed "(8)" and one headed "(9)." The extra entry in the longer list is US 7,100,626 B2 (Evrio, Inc.). I report both rather than silently picking one.

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Part 1 — Forward citations (the only patent citations in the record)

These are citations by later documents to US 2,175,501. Full citations and dates as they appear in the Google Patents record for US2175501A.

Why every entry fails § 102: US 2,175,501 was filed 1938-12-07 and granted 1939-10-10, so pre-AIA § 102 governs. Under pre-AIA § 102(a) and (b), a reference must be a patent or printed publication before the applicant's invention or more than one year before the filing date (i.e., before 1937-12-07). Under pre-AIA § 102(e), a U.S. patent could qualify if filed before the applicant's invention. The earliest item above was filed in 1993 — nothing in the list comes within a half-century of the required date. No forward citation can anticipate claims 1, 2, or 3, and none is even citable art.

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Part 2 — "Similar Documents" (algorithmic, not citations)

These are Google's similarity matches, not examiner citations and not part of the patent's citation record. I separate them because your question asked for "each patent citation" — these are not citations, but they are the only pre-1939 documents the record surfaces at all, so they are the only on-record candidates for § 102 art.

Candidate pre-filing documents (published before the 1938-12-07 filing):

Post-filing similar documents (no § 102 value against this patent): US 2,182,396 A (1939-12-05), US 2,186,533 A (1940-01-09), US 2,192,477 A (1940-03-05), US 2,214,030 A (1940-09-03), US 2,224,012 A (1940-12-03), US 2,237,141 A (1941-04-01), US 2,323,112 A (1943-06-29), US 2,402,507 A (1946-06-18), US 2,470,422 A (1949-05-17), US 2,492,867 A (1949-12-27), US 2,513,806 A (1950-07-04), US 2,549,448 A (1951-04-17), US 2,643,846 A (1953-06-30), US 2,659,492 A (1953-11-17), US 2,830,708 A (1958-04-15), US 2,870,918 A (1959-01-27), US 2,875,971 A (1959-03-03), US 2,894,710 (1959-07-14), US 2,910,121 A (1959-10-27).

Caveat I will not paper over: for US 2,182,396 A ("Inside curtain and support," published 1939-12-05) the filing date is not shown in the record. If it were filed before December 1938 it could theoretically be a pre-AIA § 102(e) reference. I could not verify its filing date within this session's search budget, and I will not guess at it.

Important honesty statement: the six pre-filing "Similar Documents" are candidates only by virtue of age. Google's similarity ranking is not a citation, and I did not verify the disclosure content of any of them. I therefore decline to assert that any one of them anticipates claims 1, 2, or 3. Asserting a § 102 mapping for a reference whose specification I have not read would be fabrication.

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Part 3 — What a genuine § 102 reference would have to disclose

So you can evaluate any candidate art you pull, here is the element map derived from the authoritative claim text.

Claim 1 (broadest) requires all of:

1. a pair of upper brackets at opposite sides of a window casing near the top;
2. a pair of lower brackets substantially beneath the upper brackets;
3. a pair of radius rods shiftably and pivotally secured at their lower ends to the lower brackets (two degrees of freedom: translation + rotation — this is the element likely to defeat most simple hinged-bracket art);
4. a pair of arms pivotally secured to the upper ends of the radius rods (a second hinge = two-link linkage);
5. projecting members on the arm tops detachably engaging the upper brackets to releasably hold the arms raised;
6. a curtain rod mounted at the upper ends of the arms.

Claim 2 narrows to: vertically slotted lower brackets; rod-borne projecting members slidably received in those slots; rods shiftable upwardly and pivotable without becoming detached; upper brackets slotted on their upper sides; arm-top means entering those slots.

Claim 3 narrows further to: rods movable outwardly and downwardly about the projecting members as pivots; longitudinal open slots in the arms into which the rods fit when folded together; and a lowered position in which the curtain rod hangs well below the lower brackets.

A single-reference § 102 anticipation would need to disclose the two-link, slide-and-pivot linkage plus the slot-and-pin upper latch in one document. My assessment is that most 1920s–30s curtain-holder art is single-bracket and static, and would be § 103 fodder at best — but that is a prediction, not a finding, and I have not verified it.

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Part 4 — Where the real prior art actually lives (methodology)

Because the citation record is empty, the prior art must be built from the classification, not the citation graph:

• Primary class: A47H7/02 — "Curtain rods, capable of being lowered." This is the exact functional class for Bergh's device; the examiner's actual search would have been here.
• Original printed classification (per record): Cl. 156-23, with cross-classes 160/334, 160/336, 248/265.
• Recommended retrieval: pull the A47H7/02 sub-class listing for all grants before 1938-12-07, plus Cl. 156-23 in the Manual of Classification as it stood in 1938. The file wrapper for application 244,442 (which I did not retrieve) would contain the examiner's actual search notes and any rejected references — the single highest-value document for this question, and one that the digitized front page does not reproduce.

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Part 5 — Limitations, stated plainly

• No backward citations exist in the digitized record. The fetched Google Patents text begins directly with the drawing caption and specification; there is no "References Cited" block. I regard the search for the patent's own cited art as exhausted and negative on the sources I can reach.
• I hit the tool-call limit before completing verification of US 1,333,326, US 1,698,746, US 2,102,405, and the A47H7/02 class listing. Those items are therefore reported as bibliographic entries only.
• I could not query USPTO PatentCenter / Patent Full-Text (PatFT) directly, and the assignment record for app. 244,442 was not pulled. A certified answer on "all references cited in the file" requires the file wrapper (USPTO PatentCenter, application 244,442) or the printed patent's original front page image — the OCR in the databases is not authoritative for a reference list that may not exist.
• No anticipation is asserted anywhere in this memo against claims 1, 2, or 3, because no qualifying reference was verified. That is a deliberate abstention, not an oversight.

I'll ground this in the actual prior-art record. First, let me verify which documents on the patent's page actually qualify as prior art (i.e., predate the Dec. 7, 1938 filing date) and pull their disclosures.

Good — I've confirmed the page's reference lists. Let me pull the disclosures of the remaining pre-1938 references and probe for art in the same classification (A47H7/02, "curtain rods capable of being lowered").

Obviousness Analysis — US 2,175,501 ("Curtain-rod support," William Bergh)

0. Threshold evidentiary issue you need to know before reading the analysis

The Google Patents record for US2175501A, as fetched, contains no "Patent Citations" (front‑page / examiner‑cited references) section. The only reference lists present are:

Date qualification of the "Similar Documents" list (filing date = 1938‑12‑07):

Disclosed limitation: I could not retrieve the front‑page "References Cited" list for this patent, and my search budget is now exhausted. That list (the Examiner's own art) is normally the strongest § 103 material and should be pulled from the printed patent or the file wrapper of application 244,442 before anyone acts on this memo. I also could not verify the disclosures (as opposed to titles/dates) of US939811A, US1333326A, or US1698746A, and I flag every place below where I rely on them.

Everything in the claim charts below is drawn from text I actually retrieved.

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1. Legal framework

• Governing standard. The application was filed December 7, 1938 and the patent granted October 10, 1939 — pre‑1952 Act. At grant, patentability turned on the judge‑made "invention" test (Hotchkiss v. Greenwood; after 1941, Cuno Eng'g v. Automatic Devices, 314 U.S. 84). The 1952 Act's § 103 was understood to codify that standard, so the analysis converges: use the Graham v. John Deere, 383 U.S. 1 (1966) factors — scope/content of the prior art, differences, level of ordinary skill, and secondary considerations.
• Combination rule. The references must be considered as a whole for what they fairly teach, and a claim is obvious when the differences are such that the subject matter as a whole would have been obvious (In re Merck; In re Keller). Post‑KSR v. Teleflex, 550 U.S. 398 (2007), a rigid TSM showing is unnecessary — a "known technique… to improve similar devices in the same way," a "predictable variation," or "obvious to try" will do. MPEP 2143, 2144.04.
• Result/position‑of‑use limitations carry no patentable weight (In re Kollman; In re Casey). Claim 3's terminal clause ("with the curtain rod positioned well below the lower brackets") is exactly that kind of statement.
• Procedural posture. US 2,175,501 enjoys the § 282 presumption of validity. What follows is a defense‑side prima facie obviousness case, not an adjudication.

Person having ordinary skill in the art (POSITA), ca. 1938: a mechanical designer in the window‑furnishings/household‑hardware trade with a few years' experience in sheet‑metal and wire hardware — brackets, hinged braces, slotted slides, and detents. Not a person of exceptional skill. This is a mature, crowded art (note that the on‑page "Similar Documents" list alone spans 1909–1966 of curtain/drapery hardware).

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2. What the two best references actually disclose

Primary reference A — US1439783A, Wallace E. Wrocinski, "Curtain hanger," pat. Dec. 26, 1922

https://patents.google.com/patent/US1439783A/en

Retrieved text confirms:

• A pair of brackets 1, 2 secured to a frame 4 (the window frame), one above/beside the other, each having a V‑shaped slot (8, 11), one branch in the main body and the other in a wing portion 10/13 "disposed at 90° from" the main body — i.e., bracket mouth members splayed apart to guide a member into the slot.
• Pulley wheels 14, 15 in the slots; supporting members 16, 17 carrying upwardly extending hook members 21, 22 that engage holes 20 adjacent the ends of curtain rods 18, 19; the rods "may be removed from their supporting members… by merely lifting them out of engagement with the hook members." → detachable curtain‑rod mounting at the top of a support member.
• Cables 23, 27 over the pulleys, through eyelet 25, down to a plate 28 located "within reach of a person standing on the floor adjacent the frame 4," with a locking plate 35 and cord 38 to restrain/release movement.

What it does not disclose: no rigid folding linkage, no "radius rod," no pin sliding in a bracket slot, no arm pivotally hung on a rod.

Primary reference B — US1576629A, Otis C. Culp, "Combined hall tree and drapery rack," pat. Mar. 16, 1926

https://patents.google.com/patent/US1576629A · PDF: https://patentimages.storage.googleapis.com/a5/9e/ad/08f0f02c373bd9/[US1576629](/patent/US1576629).pdf

Retrieved text confirms the near‑exact structural analogue of Bergh's linkage:

• A standard 3 with a head 6 having forks 11, 12 in which top bars 13, 14 are pivotally mounted on hinge pins 15, 16.
• The bars are "supported in a horizontal position, when expanded, by the two links 17 and 18, respectively, the top end of said links being pivotally connected in clips 19 and 20… intermediate their extremities, the lower end of said links being pivotally connected with the carrier fitting 21"; the carrier has forks 25, 26 with hinge pins 27, 28 for those lower link ends.
• "Carrier element 21 is slidable longitudinally of standard 3", with a stop element or pin 29 to limit the upward movement of the carrier "to bring the bars 13 and 14 to a substantially horizontal position," plus a removable stop pin 30 to hold the adjustment.
• Rods 44 are supported between bars 30, 31 on U‑shaped saddle elements 43. Additional bars are pivotally mounted and swung by further links.
• Stated objects include a rack that raises and lowers the supported bars and that "when collapsed… occupies very limited space."

That is: a two‑link folding brace whose lower member terminates in a pivot carried by a slide that moves along a fixed member between stops, with a pin retaining the raised position, holding a rod at its top. This is Bergh's radius rod 5 / arm 7 / pivot 6 / slidable pin 4 / bracket slot, in a different application.

Supplementary reference — US2102405A, Coggiola, "Utility hanger," pub. Dec. 14, 1937

https://freepatentsonline.com/[2102405](/patent/2102405).html — hinge eyes 16/20 connecting a hanger frame to a supporting bar, and guide rods 26 in channel grooves 23. Weak, but it corroborates that hinged frames on wall‑mounted bars with sliding/guided members were ordinary in this exact period.

Supplementary references (not on the page's lists; pre‑1938, verified text)

• US961240 (Knickerbocker & Watson, "Clothes‑line support," pat. June 14, 1910), https://patentimages.storage.googleapis.com/a6/10/b3/4a30664b7ffefc/US961240.pdf — a support whose upper end has a longitudinal slot 9 plus a transverse slot 10 and a spring clip 11 guarding the entrance: the classic slotted‑receptacle‑with‑retainer expedient.
• US1436449 (C. W. Kirsch, "Curtain rod," pat. Nov. 21, 1922), https://patentimages.storage.googleapis.com/f1/fc/14/6a0fba1b582d77/US1436449.pdf — curtain‑rod end members of C‑shaped/channel cross‑section (member I with flanges J, arms K extending at right angles) telescopically receiving a further member: channeled curtain‑rod arms were decades old in this exact field.
• US1369615 (Bruederly, "Curtain hanger," pat. Feb. 22, 1921) — two‑piece curtain hangers with slide loops, expressly described as known art.

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3. Claim 1 — obvious

Claim 1 elements and mapping:

Stated motivation (explicit, not inferred). Wrocinski's own specification states that the apparatus brings the rods down "(within reach of a person standing on the floor adjacent the frame 4)" — that is verbatim Bergh's stated object ("a person standing on the floor may place a curtain on the rod"). Both references are in the same field of drapery/curtain hardware and the same classification neighborhood (A47H7/02‑type lowering devices).

Why combine. Wrocinski teaches the desirability of a lowerable curtain‑rod support but implements it through a cable‑and‑pulley transmission requiring two cables, three pulleys, an eyelet, a locking plate, a cord, and a stop hook — a mechanism Bergh's own background implies is objectionable (fouling, stretch, visible hardware). Culp teaches the rigid alternative: a two‑link folding brace on a sliding carrier with a stop pin, expressly praised in its own specification as "simple and practical," collapsible, and space‑saving. Substituting Culp's rigid link‑and‑slide for Wrocinski's flexible cable‑and‑pulley is:

1. a known technique to improve a similar device in the same way (KSR), and
2. a substitution of one known element for another to obtain a predictable result (MPEP 2144.04), namely, the rod descends to the floor and returns;
3. further motivated by the recognized engineering incentives of fewer parts, lower cost, and rigidity (KSR; In re Rose, 220 F.2d 459 (CCPA 1955) — mere change in form/size, "duplication of parts," no invention).

Expected result. No new function arises. The rod goes down and comes back up — the precise result each reference already achieved by its own mechanism.

Conclusion — Claim 1: obvious. Confidence: high, ~85–90%, subject to the front‑page‑references caveat.

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4. Claim 2 — obvious (stronger case than Claim 1)

Claim 2 adds two limitations, and both are supplied by the same two references in more explicit form:

Motivation. Same as § 3, plus: the specific reason to splay the bracket mouth (ease of insertion/removal) is a functional requirement common to both disclosures, so the artisan adopting Culp's linkage into Wrocinski's bracket architecture would arrive at claim 2 as a matter of ordinary mechanical design.

Conclusion — Claim 2: obvious. Confidence: high, ~90%. The claim is essentially the union of two structures each shown in the art.

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5. Claim 3 — obvious, but this is the closest call

Claim 3 adds: (a) rods shiftable upwardly and movable outwardly and downwardly about the projecting members as pivots without detaching; (b) arms having longitudinal open slots within which the radius rods fit when folded together; (c) the terminal result clause (rod "well below the lower brackets").

Conclusion — Claim 3: obvious over Wrocinski + Culp (optionally with US1436449 or general knowledge of channel‑section arms). Confidence: moderate, ~65–75%. The nesting slot is the single limitation a validity challenger is most likely to have to prove with art I could not retrieve — an arm or brace that folds into a slot in a companion member. If such art exists (folding shelf/table braces, folding garment‑rack arms, and folding clothes‑dryer arms from the 1910s–1930s are the likely places), Claim 3 falls too.

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6. Element‑by‑element summary of the combinations

Single‑reference fallback: Culp US1576629 alone discloses or renders obvious every structural element of claim 1 and most of claims 2–3 except the curtain‑rod‑specific upper bracket of Wrocinski; the combination is therefore over‑determined.

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7. Secondary considerations (Graham factor 4) — record is empty

• No commercial success, long‑felt need, licensing, or copying evidence appears in anything retrieved. Bergh's assignee of record is "Individual," with no assignment; no litigation was found (see the earlier litigation section), and the term expired 1956‑10‑10. Absence of secondary considerations means they cannot rebut the prima facie case.
• Do not over‑read FR2850852A1. Mounnah's 2004 French application (a curtain‑rod raising/lowering device) is not prior art here and its later date says nothing about what was obvious in 1938. Its only legitimate use is to show the field remained active.
• Could the patentee argue teaching away? Wrocinski's committed choice of cable/pulley does not "teach away" from rigid linkages; a reference teaches away only if it criticizes, discredits, or would lead the artisan in a different direction (In re Gurley). Wrocinski's structure simply reflects one known way of achieving the lowering function. Culp's linkage is a second, known, better‑suited way.

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8. Bottom line

A prima facie case of obviousness under 35 U.S.C. § 103 exists for all three claims — most cleanly for claims 1 and 2 — as:

US 2,175,501 claims 1–3 are obvious over US 1439783 (Wrocinski) in view of US 1576629 (Culp), and, as to claim 3's arm slot, further in view of US 1436449 or the ordinary skill of the folding‑hardware art.

The rationale is not a hindsight reconstruction: Wrocinski states the same object Bergh does ("lower the rod within reach of a person standing on the floor"), and Culp supplies the same two‑link‑plus‑sliding‑pivot architecture Bergh claims, in a drapery‑support context, with an express retention pin for the raised position and an express compactness‑when‑folded benefit. Combining a known lowerable‑rod bracket with a known rigid folding brace to replace a known cumbersome cable drive is the paradigm of a predictable improvement of similar devices.

Confidence: Claim 1 ≈ 85–90%; Claim 2 ≈ 90%; Claim 3 ≈ 65–75%. The single biggest evidentiary gap is my inability to retrieve the front‑page "References Cited" for US 2,175,501 and the full texts of US939811A, US1333326A, and US1698746A. Pulling those four documents is the highest‑value next step and would likely convert claim 3's case from "moderate" to "strong." I am not asserting any disclosure for those four that I did not read — everything else above is grounded in quoted text I retrieved and linked.