US 3762407

I'll search for this specific patent number, including any 2026 CAFC docket activity.

US Patent 3762407 — Analyst Summary

Disambiguation note first: Queries for "3762407" also surface JP 3762407 B2, a Japanese patent (Merck's sitagliptin/phosphate-hydrate family, expiry extended into 2026, litigated in Tokyo District Court). That is a different, unrelated patent sharing a numeric string. Everything below concerns only US 3762407 A.

Bibliographic Data

Abstract (verbatim)

"Apparatus for providing a breathable gas to an individual in an emergency situation is provided in practice of this invention. The apparatus contains a breathable mixture of gas for a prolonged period and, when actuated, provides about 10 minutes of gas to the user. The gas is contained at high pressure in a lightweight long tube coiled about a combined fill valve, pressure regulator, flow control, pressure gauge, and actuation mechanism. This assembly is in a canister and actuated by perforating a pressure containing diaphragm between the gas storage reservoir and the pressure regulator. The canister is connected to the back of a plastic hood that is fittable over a user's head so that the canister is arranged during use at the nape of the user's neck so as not to interfere with any emergency operations and, for example, to permit the user to wear a helmet or the like. Gas from the canister passes into the hood at a substantially constant rate and is vented as required through a check valve. An elastic band around the person's neck limits leakage."

Overview of the Independent Claim

This patent has exactly one independent claim, claim 1, drafted in "improvement" (Jepson-style) form: the preamble recites the prior-art combination, and the invention lies in the "improvement wherein" clause. Claims 2, 3, and 4 all depend from claim 1. Because the patent's 4 claims are printed in abbreviated/omitted form in the source (some intervening claims appear omitted from the grant text as rendered), the following is grounded in the language actually appearing.

Claim 1 (independent) — plain language:
A survival support device built from these baseline elements:

• a substantially impervious flexible bag large enough to fit over a user's head, with a transparent portion at least at the front;
• one-way means allowing gas to flow out of the bag but blocking flow in (the exhalation check valve);
• a hollow coil of high-pressure tubing holding breathable gas at high pressure;
• a regulator inside the coil that holds outlet pressure substantially constant across a broad range of inlet pressures, giving a substantially constant output flow;
• an actuator inside the coil that, essentially instantly, connects the regulator to the gas reservoir;
• support means attaching the coil to the rear of the bag, resting against the nape of the user's neck.

The improvement (the point of novelty) is geometrical/packaging: the tubing coil is at least an outer quadrilateral (squared-off) coil wrapped around a substantially rectangular regulator and actuator, plus an inner quadrilateral coil concentric with the outer coil and closely conforming to the shape of those rectangular components — thereby minimizing the total volume of the gas supply. This is the FIG. 8–10 "quadrilateral" embodiment, contrasted with the circular-coil embodiment of FIGS. 1–3.

Dependent Claims (brief)

• Claim 2 (dep. claim 1): Adds the actuation hardware — a diaphragm between reservoir and regulator able to withstand substantial pressure; a spring-biased plunger with a perforating tip mounted to travel far enough to pierce the diaphragm; and a removable retaining pin that temporarily holds the plunger back (the pull-pin "cocked" state).
• Claim 3 (dep. claim 1): Adds a pressure gauge and a pressure-containing fill valve, both in communication with the tubing coil; and specifies that the gauge, fill valve, and actuator are all accessible from the ends of the hollow cylinder.
• Claim 4 (dep. claim 1): Specifies that the bag's transparent portion is flexible.

Regulatory / Litigation Status — CAFC 2026 Dockets

I found no 2026 Court of Appeals for the Federal Circuit docket, opinion, or order involving US 3762407, and I state that as a low-confidence negative rather than a verified fact — I cannot query PACER or the CAFC docket system directly, only general web search. Practically, such a docket is highly unlikely: per the record above, this patent expired on 1990-10-02 (anticipated term), so any 2026 appeal concerning it would be anomalous. Search hits for "3762407" + "2026" all resolved to unrelated matters (e.g., Ironburg v. Valve, No. 2024-2088; Spero v. Mercedes-Benz, Nos. 2025-1306/1307/1473; and the Japanese sitagliptin litigation). None cite US 3762407.

Related Family / Citation Context (from the record)

• Cited prior art (5): US 456,687 (Bader); US 2,697,538 (Seeler, aneroid pressure release); US 3,292,821 (Cowley, coin-operated oxygen dispenser); US 3,505,997 (Abbott Lab, oxygen breathing apparatus); US 3,633,596 (US Navy, diaphragm valve).
• A sibling case: the "Similar Documents" list includes US 3762604 A (1973-10-02) "Survival support device" — same issue date as the subject patent, consistent with the two being division/companion filings of the 1971 parent application.
• Notable later citing art: US 3,976,063 (Bendix, escape breathing apparatus); US 4,221,216 and US 4,233,970 (Robertshaw Controls, emergency escape breathing apparatus); US 4,405,978 (Portable Air Supply Systems); US 4,629,571 (Lockheed, smoke mask); US 4,889,113 (L'Air Liquide); US 6,247,471 (Essex PB&R); US 10,335,617 (L'Air Liquide).

Uncertainty Flags

1. Claim set completeness: The full text as rendered shows four claims, but the transition from the description into the claim list contains apparent omissions (the narrative lists claim 1 then jumps into claim 2, 3, 4 language fragments). I cannot confirm whether the granted patent contains additional claims not captured in this rendering. Anyone relying on the exact claim scope should pull the official USPTO PatentCenter / patent image PDF.
2. Typographical errors in the source (e.g., "contanst" for "constant," "vlave" for "valve," "conning" for "donning," "deivce") are reproduced in the OCR and should not be treated as technical terms.
3. CAFC negative result is a search-based conclusion, not an authoritative docket check.

I'll search for litigation records involving US patent 3762407.

Let me search additional litigation-specific sources.

No US litigation found for US Patent 3762407

I searched litigation-oriented sources (general web, patent-specific queries, and targeted strings for the number), but I could not identify any litigation — past or present — involving US Patent 3762407. I'll state the basis for that conclusion, then flag an important false-positive you should be aware of.

1. Litigation list for US 3762407

No US District Court, CAFC, or PTAB/IPR proceeding naming US 3762407 was found. Given that the patent is US3762407A, "Survival support device," assigned to Lear Siegler Inc., filed 1972-04-24, granted 1973-10-02, and showing "Expired – Lifetime" with an anticipated expiration of 1990-10-02, it has been off-term for over 35 years. Any US enforcement action would necessarily have been historical (1973–1990), and none surfaced in my searches.

2. Critical caveat — a same-numbered but wholly unrelated patent

My searches repeatedly returned a hotly litigated patent whose number also reads "3762407" — but it is Japanese Patent No. 3762407 (JP3762407B2), not the US patent you asked about. Per your instruction not to conflate similar/coincident numbers, I am explicitly not reporting this as litigation for US 3762407, but you should know it exists so it isn't mistaken for a hit:

• JP Patent 3762407 (Japanese national phase of a DPP-4 inhibitor compound case) — subject matter: β-aminotetrahydroimidazo[1,2-A]pyrazines / sitagliptin (Januvia®), Merck Sharp & Dohme.
• Merck Sharp & Dohme LLC v. Sawai Pharmaceutical Co., Ltd. and Medisa Shinyaku Inc., Tokyo District Court, complaint and preliminary injunction motion filed 2023-10-06 (announced 2023-10-26). Issue: whether the term-extended JP 3762407 right reaches the generics' anhydrate formulation. Reported terminated 2026-02-03 after Sawai/Medisa fully conceded ("認諾"/acknowledgment of all claims).
• Sources: https://www.msd.co.jp/news/product-news-20231026/ ; https://www.msd.co.jp/news/product-news-20260203/ ; https://www.tokkyoteki.com/2026/02/msd-sitagliptin-phosphate-hydrate-2.html

This is a different patent in a different jurisdiction with different subject matter (pharmaceutical compound vs. emergency breathing apparatus). It is not litigation involving US 3762407 and should not be cited as such.

3. Confidence / limitations

• I am high confidence that no litigation is publicly associated with US 3762407. It is a 1973 mechanical/life-support patent that expired in 1990.
• Lower confidence / unimplemented steps: I was unable to complete direct queries against Unified Patents' litigation portal, PACER, and CourtListener before my search budget was exhausted. Those databases are the authoritative sources for a negative-clearance conclusion. To be fully certain, you should run the number directly against:
  • Unified Patents litigation: https://portal.unifiedpatents.com/litigation/caselist
  • PACER Case Locator (search "3762407" as patent-in-suit)
  • CourtListener / RECAP: https://www.courtlistener.com

Bottom line: Based on available search results, no litigation involving US Patent 3762407 is known. The only "3762407" litigation that appears in search results is a Japanese patent of the same number, unrelated to this US patent.

Proceedings overview

Zero AIA trial proceedings on file for US 3,762,407 — the USPTO Open Data Portal returns no IPR/PGR/CBM, my web searches surfaced none, and the Google Patents record for the patent lists no PTAB or reexamination activity; the bottom-line posture is not "hardened by surviving IPRs" but something stronger and simpler for a defendant: the patent expired on 1990-10-02, roughly 22 years before the first AIA petition could even have been filed, so there is no live patent to attack and no PTAB record to mine.

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No proceedings to itemize

There is no proceeding number, petitioner, panel, institution decision, FWD, settlement, or appeal to report. I will not manufacture one. What follows is (a) the verification trail, (b) why the absence is structural rather than merely unlucky, and (c) what it means for a demand letter.

Verification trail

• Structured source (canonical): the "PTAB proceedings on file" block states the USPTO ODP API returns no AIA trial proceedings for this patent as of the most recent ingest. I adopt that.
• Google Patents (https://patents.google.com/patent/US3762407/en) — the record shows the "Cited By (66)" and "Patent Citations (5)" tables, classifications A62B17/04 and A62B7/02, and the 1972-04-24 filing / 1973-10-02 grant / 1990-10-02 anticipated expiration, but no "PTAB" / AIA trial section of the kind Google populates for patents that have been through the Board.
• Web search returned no IPR, PGR, CBM, or PTAB decision citing US 3,762,407. It did return noise I want to flag so it is not mistaken for a hit.

⚠️ False-positive flag (do not be misled)

Searching "US 3762407" surfaces Japanese-language pharma articles about JP Patent No. 3762407 — the Merck/MSD sitagliptin salt patent litigated against Sawai/Medisa in the Tokyo District Court (see e.g. https://www.s-cubecorp.com/2026/02/06/). That is a different patent, in a different jurisdiction, on a different subject matter. It shares only the numeric string. It has nothing to do with US 3,762,407 and nothing to do with PTAB. Likewise, citations like "Duenser '376" and "JP 3762407 B2" in unrelated search-engine-art tables are noise.

Why there is no PTAB record (structural, not accidental)

1. The AIA trial regime postdates the patent. IPR/CBM became available 2012-09-16 and PGR 2012-09-16 (for post-AIA patents). US 3,762,407 issued 1973-10-02 under a 17-year term and reached its anticipated expiration on 1990-10-02. It was expired for over two decades before the Board's first petition existed. A PGR is legally unavailable (pre-AIA patent); a CBM is unavailable (not a financial-services business-method patent, and the CBM program is sunset); an IPR on an expired patent is theoretically possible only where the patent is still being asserted for back damages in a live district-court case — and there is no indication of such a case; nothing in the record, and nothing I found, suggests any assertion of US 3,762,407 in the AIA era.
2. No pre-AIA reexamination either, as far as the record shows. For a 1973 patent the contemporaneous Office-side invalidity tools were ex parte reexamination (from 1981) and inter partes reexamination (from 1999). The Google Patents record displays no reexamination certificate and no "Also published as" reexam entry.
3. Related family member — US 3,762,604, "Survival support device," issued 1973-10-02 (the sibling/parent filing from Ser. No. 141,781, filed 1971-05-10, of which US 3,762,407 is a division). It, too, is long expired and likewise shows no PTAB activity in the record I reviewed. If you ever need to check the family for Board history, that is the companion patent to pull.

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Strategic summary

Claim status. US 3,762,407 issued with 4 claims: independent claim 1 (survival support device having a flexible head bag, a one-way exhaust means, a hollow coil of high-pressure tubing, regulator means within the coil, actuator means within the coil, nape-of-neck mounting — the improvement being outer/inner quadrilateral coils conforming to a rectangular regulator/actuator body to minimize gas-supply volume), dependent claim 2 (burst diaphragm + spring-biased perforating plunger + removable retaining pin), dependent claim 3 (pressure gauge + pressure-containing fill valve, all accessible from the ends of the hollow cylinder), and dependent claim 4 (flexible transparent bag portion). None of claims 1–4 has been canceled, amended, or held unpatentable by the PTAB — not because they were tested and survived, but because no AIA trial was ever filed. There is likewise no reexamination certificate narrowing them. Treat all four as issued-but-expired, not as "sustained." The distinction matters: "the PTAB sustained claims 1–4" is a false statement; "no PTAB proceeding ever existed" is the accurate one.

Estoppel landscape. There is no § 315(e)(2) estoppel to map, because there is no petitioner and no final written decision. A defendant today faces no estoppel constraints from this patent's history. Conversely, there is no FWD invalidating art to borrow, no claim-construction or priority ruling to cite, and no Board reasoning to leverage. If someone hands you a demand letter citing US 3,762,407, your cleanest defenses are threshold and dispositive rather than PTAB-based: (i) expiration — the patent term ended 1990-10-02, so it cannot be infringed by post-1990 conduct; (ii) § 102(b)/§ 103 on the 1971–1972 priority — the art that would have been used against it (e.g., the Seeler pressure-release device, US 2,697,538, cited on the face; the Cowley oxygen dispenser, US 3,292,821; the Abbott oxygen breathing apparatus, US 3,505,997; the Navy diaphragm valve, US 3,633,596) is now decades out of copyright-clean reach but remains materially relevant to any theory that resurrects the claims; and (iii) laches/§ 286 damages limitation on any stale-claim theory.

Pattern signals. None of the usual tells are present: no serial petitioner (there is no petitioner at all), no patent-owner appeal activity, no defensive aggregator (no Unified Patents or RPX filing on this number), and no district-court assertion I could locate in the AIA era that would have created § 315(b) exposure. The only "assertion" energy attached to the number "3762407" in search results belongs to a Japanese pharmaceutical patent — a sound-alike number, not this patent. For a 1973 Lear Siegler survival-hood patent that expired in 1990, the absence of PTAB activity is not the "well-asserted patents attract IPRs" signal in reverse; it is the expected state of affairs for a patent that left the enforceable population before the Board existed.

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Recommended next steps

• If you are a defendant and a demand letter cites US 3,762,407: the threshold answer is that the patent expired 1990-10-02 (per the Google Patents legal-status data: "Anticipated expiration 1990-10-02," "Expired - Lifetime"). There is no FWD to quote, because none exists — so do not assert one. Instead, demand the plaintiff identify the specific § 271 act, the date, and the asserted ones of claims 1–4, then point to the expiration date and 35 U.S.C. § 286's six-year damages bar.
• Confirm the negative yourself before relying on it in a filing. Pull the PTAB E2E / Patent Trial and Appeal Board End-to-End system (https://ptacts.uspto.gov) and the USPTO PatentCenter record (https://patentcenter.uspto.gov) for 3,762,407, and check the Patent Assignment and reexamination histories. The structured ODP block is the canonical list and it is empty, but a one-page E2E printout is the artifact you attach to a Rule 11 / § 285-safe letter.
• If you need family context: also pull US 3,762,604 (the companion "Survival support device" patent from the same 1971-05-10 parent application, Ser. No. 141,781). It is the natural cross-reference if opposing counsel argues the divisional family has any residual vitality; it is expired on the same vintage.
• No trial-stage milestones to track. With no institution, there is no § 314(b) one-year clock, no oral-hearing date, and no § 318(a) FWD due date. There is nothing active. If a search result ever shows you an IPR number for this patent, treat it as a mis-identified number (most likely the JP 3762407 confusion flagged above) until you verify it on E2E.

Caveat on completeness: the Google Patents record is authoritative for the grant, term, and citation data and shows no PTAB block; the ODP block is authoritative and empty; my web searches corroborated both but surfaced only false positives. I did not find, and therefore cannot rule out, an unpublished or pre-digital-era reexamination file; if the stakes warrant it, order the full file wrapper from PatentCenter rather than relying on third-party databases. I found no Federal Circuit appeal and no CourtListener docket for this patent number.

I'll start by checking the primary sources for any recorded assignment activity on this patent.

Let me try the USPTO assignment databases directly and cross-check the corporate history.

Let me probe the assignment databases and related family members more specifically.

Inventors

Named inventor (sole): David E. Shonerd, Santa Barbara, California (per the printed patent front page, "[75] Inventor: David E. Shonerd, Santa Barbara, Calif.").

• Employer at filing: Presumed Lear Siegler, Inc. — the invention was assigned to Lear Siegler, which is named as original assignee and as the "Application filed by" party in Google Patents' legal events. The specific Lear Siegler division/plant is not determinable from the record I retrieved; I did not locate a Santa Barbara facility in the 1987 divestiture coverage, so I will not guess which operating unit employed him.
• Unusual patterns: None observable. I have no evidence of inventor departure, and no post-issuance assignment activity of any kind. There is no data from which to test the "all inventors departed within 12 months" fire-sale precursor.
• Related filing: This patent is a division of Ser. No. 141,781, filed 1971-05-10 (per the patent's CROSS REFERENCE TO RELATED APPLICATIONS). A sibling division, US 3,762,604, also titled "Survival support device" and also published 1973-10-02, appears in Google Patents' "Similar Documents" list; I did not independently verify its assignee, so treat that as unconfirmed.

Original assignee

Lear Siegler, Inc. (Santa Monica, California), a publicly traded diversified aerospace/industrial conglomerate.

• Primary line of business: Conglomerate — aerospace instruments and avionics, flight controls, drone aircraft, aircraft fuel tanks, bearings, automotive seating, and industrial products. The surviving testimonial from the 1987 divestiture press (LA Times, 1987-03-26) lists the aerospace units alone at roughly $700M of a ~$2.1B-scale enterprise.

• Did they ship a product embodying the claims? Unclear / not verified. The specification is written as a fielded hardware disclosure (0.308-caliber live-fire test of the coiled-tubing reservoir, quoted gauge/regulator pressures, 3.5 lb prototype weight, Navy-style shipboard-fire use case), which is consistent with a government/industrial program rather than a shelf product. I found no product literature, catalog, or Navy contract record tying the claimed hood to a Lear Siegler part number, so I am explicitly declining to assert commercialization.

• Current status: No longer exists as an independent entity. Forstmann Little & Co. took Lear Siegler private in a $2.1B leveraged buyout (Dec 1986 / announced Jan 1987) and then broke it up, selling the divisions piecemeal through 1987–88:

  • Lear Siegler Instrument & Avionic Systems Corp., Lear Siegler Avionic Systems Holding Corp., and Lear Siegler International Corp. → Smiths Industries PLC, $350M (UPI, 1987-07-23).
  • Two aerospace divisions → General Electric Co. PLC of London, $205M (LA Times, 1987-08-01).
  • Four further units (American Electric, Reznor, Janitrol Aero, Management Services Corp.) put up for sale (NYT, 1988-03-10).
  • Lear Siegler Seating Corp. → management-led LBO, $507M (1988), which is the ancestry of today's Lear Corporation seating business (NYT, 1988-10-10; Crain's Detroit, 2003-01-13).
  • Piper Aircraft was excluded from the aerospace sale group.

  This was a leveraged take-private and piecemeal breakup, not a Chapter 7/11 bankruptcy. That distinction matters for NPE signal #6 below.

Important caveat: The Lear Siegler entities above were sold as operating businesses. None of the press coverage I retrieved addresses intellectual property transfers, and I found no recorded patent assignment moving US 3,762,407 to any of these buyers.

Assignment timeline

I could not retrieve a live assignment record — and I am reporting that as a gap, not as a finding of "no assignments." My searches against the Assignment Center indices returned only the Google Patents bibliographic page, not reel/frame data. So I cannot print reel/frame numbers without fabricating them, which I will not do.

What the record does show:

• Google Patents legal events for US 3,762,407 contain no reassignment entries. The complete event list I retrieved is: 1972-04-24 "Application filed by Lear Siegler Inc"; 1973-10-02 "Application granted"; 1973-10-02 "Publication of US3762407A"; 1990-10-02 "Anticipated expiration"; status "Expired – Lifetime." Google Patents normally renders recorded reassignments as discrete legal events with reel/frame, and none appear.
• "Current Assignee" and "Original Assignee" are both listed as Lear Siegler Inc, i.e. no change at the bibliographic level.
• Application number: US 247,107. Family ID: 22933582. Priority/filing date: 1972-04-24.

Prosecution attorney (not an assignment correspondent — noted to prevent conflation): the patent face lists Christie, Parker & Hale as attorney of record. That is prosecution counsel, appearing once, on a single patent. It is not a recorded-assignment correspondent, and a single appearance is not a signal under your rule #3. I have no address for them as recorded in any assignment instrument, and I am not going to supply one from memory.

Net effect: the only transaction I can substantiate is the original assignment from Shonerd to Lear Siegler, Inc., the standard employer-assignment implied by Lear Siegler's status as both "original assignee" and the filing party. I could not verify its reel/frame. If the Assignment Center in fact returns records, they are records I failed to reach, not records I examined and cleared.

Timeline diagram

timeline
    title Ownership of US 3762407
    1971 : Parent application filed
    1972 : Divisional application filed
         : Lear Siegler Inc named as assignee
    1973 : Patent issued to Lear Siegler Inc
    1986 : Lear Siegler taken private by Forstmann Little
    1987 : Lear Siegler divisions sold off piecemeal
    1990 : Patent term expires

(The 1986 and 1987 entries are corporate events affecting the assignee as an entity; I found no patent-assignment instrument corresponding to them.)

NPE / troll-pattern signals

Verdict

Insufficient data — and independently, moot.

The evidence supports only the original employer assignment: Shonerd → Lear Siegler, Inc., with Lear Siegler still shown as both original and current assignee, and Google Patents' legal-events list containing no reassignment entry across the patent's entire life (events run 1972-04-24 filing → 1973-10-02 grant → 1990-10-02 anticipated expiration). I could not retrieve a live reel/frame and am recording that as a retrieval failure rather than certifying that no instrument exists. Substantively, the NPE question is closed regardless: the patent expired 1990-10-02 and the original assignee was dissolved in the 1986–88 Forstmann Little breakup, so there is no assertion window, no living owner to fire-sell to, and no litigation history. All eight NPE signals score not present on the record retrieved.

Verification links: USPTO Assignment Center — https://assignmentcenter.uspto.gov/ (search patent number 3762407); legacy UI — https://assignment.uspto.gov/patent/index.html; USPTO Patent Center — https://patentcenter.uspto.gov/; Google Patents legal events — https://patents.google.com/patent/US3762407/en.

What would change this verdict: a recorded assignment on a reel/frame I did not reach. If Assignment Center returns any post-1973 instrument for 3762407, the decisive fields to pull are the execution date, the correspondent of record, and the assignee address — and I'd want to know whether the recording predates 1990-10-02, because anything after that date cannot support an assertion theory on this patent.

I'll research each cited prior-art reference for US 3762407. Let me search the USPTO/Google Patents records for each.

I have the core records. Let me verify a few bibliographic details (inventors, filing dates) and check a related reference that surfaced.

Prior-Art Analysis — US Patent 3762407 ("Survival support device")

Scope and method

US 3762407 A (David E. Shonerd; Lear Siegler Inc.; filed 1972‑04‑24, granted 1973‑10‑02; a division of Ser. No. 141,781, filed 1971‑05‑10) has exactly five examiner-cited "Patent Citations," per the authoritative record I was given:

Two caveats up front, because they matter for the § 102 answer:

• I could not retrieve the examiner's actual Office action / statement of rejection for this case (it is not in the material provided and I exhausted my search budget before reaching USPTO file-wrapper sources). The mapping below is therefore my inference, from each reference's disclosed subject matter versus the granted claim language — not a transcription of the examiner's stated grounds.
• Note the distinction between the 5 "Patent Citations" (true prior art, examiner-cited) and the 40+ "Cited By" documents (later patents that cite this patent — those post‑date 1973 and are not prior art against US 3762407), and the "Similar Documents" list, which includes the sibling US 3,762,604 "Survival support device" (same 1973‑10‑02 issue date; a companion division of the same 1971 parent — same-family, not prior art).

The governing § 102 framework

US 3762407 is pre‑AIA and is a division, so its effective filing date for subject matter carried over from the parent is 1971‑05‑10. That produces two distinct § 102 cutoffs:

• § 102(b) statutory bar — references patented/published more than one year before the effective filing date, i.e. before ~1970‑05‑10. References 1–4 all qualify.
• § 102(a)/(e) — the only reference that does not clear the § 102(b) one-year bar is US 3,633,596, granted 1972‑01‑11. Because it was filed 1970‑07‑23 — before the parent's 1971‑05‑10 filing date — it can only be reached as § 102(e) art (in this era, "by another, filed before the applicant's invention"), or under § 103 on that basis. It is not § 102(b) art against this patent.

Because claim 1 is drafted in Jepson ("improvement wherein") form, its preamble elements (bag, one-way valve, coiled high-pressure reservoir, regulator-inside-coil, actuator-inside-coil, nape-of-neck mounting) are, by the drafter's own format, characterized as the admitted prior-art combination; the asserted novelty is the improvement: an outer quadrilateral coil wrapped around a substantially rectangular regulator/actuator, plus a concentric inner quadrilateral coil closely conforming to those rectangular components to minimize gas-supply volume. That framing is decisive for the anticipation analysis below.

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Reference-by-reference

1) US 456,687 — Bader smoke-protection headpiece (transparent lookout)

• Full citation: US 456,687, issued 1891‑07‑28, William Bader. (The Google Patents citation row displays the patentee's name in the title field; no separate formal title is given in the citation list.)
• Description (from the specification text retrieved): A smoke-protection headpiece of smoke‑tight but flexible material covering head and shoulders, with a transparent "lookout" (metal-framed glass panes) at the front; an air-cylinder B, an air-pump C for charging, a gage D indicating charge; flexible pipes/tubes E delivering air from the cylinder to the interior near the mouth and nostrils; an exit-pipe F above the nose for exhalation; and a valve E on the pipe entering the cylinder, with an indicator plate, to regulate ("regulate and determine accurately by inspection") the air discharge. The headpiece is fitted to the wearer and secured by straps.
• Potentially relevant claim(s): Preamble of claim 1 (head-covering enclosure, transparent portion at the front, pressurized breathable-gas source delivered into the enclosure, means permitting outflow/inhibiting inflow = exit pipe F, regulator/valve). Claim 3 (a gauge in communication with the supply, and a regulable fill/charging path). Claim 4 (the notion of a clear viewing region).
• § 102 assessment: Bader is a strong but incomplete § 102(b) reference for the preamble concepts — it antedates by ~80 years and discloses a transparent-front breathing hood with stored compressed air, a gauge, a flow-regulating valve, and an exhalation outlet. It does not disclose a flexible bag (its frame is rigid), a coil of tubing, a quadrilateral coil, an in‑coil regulator/actuator, or nape-of-neck mounting. Accordingly it does not anticipate claims 1–4 as a whole, but it is squarely on point for the admitted-prior-art preamble and is a natural § 103 combination reference. Note the irony: Bader's rigid glass transparent portion is what claim 4's "flexible transparent portion" is measured against.

2) US 2,697,538 — Seeler, "Aneroid actuated pressure release device"

• Full citation: US 2,697,538, filed 1949‑10‑28 (Ser. No. 124,161), granted 1954‑12‑21, Henry Seeler.
• Description: A pressure-release device whose chamber (11) is sealed from a fluid-pressure source by an imperforate sealing disk/diaphragm (14) clamped between threaded washers (13, 15). A spring-urged plunger (16) carries a piercing point (17) and apertures (18) that open a flow path once the plunger advances to puncture the disk; an O‑ring (22) prevents leakage back past the plunger. The plunger is held retracted by latch members (40, 41) that are released either automatically (aneroid bellows 26 at altitude) or manually by a pull cord (33) after removal of a safety pin (39).
• Potentially relevant claim(s): Claim 2 — almost element-for-element: a diaphragm capable of withstanding substantial pressure; a plunger with a perforating tip; mounting for movement toward the diaphragm far enough to penetrate it; spring bias toward the diaphragm; and a removable retaining pin (safety pin 39) that temporarily holds the plunger away.
• § 102 assessment: Seeler is the single best § 102(b) reference against the added subject matter of claim 2. Every functional element of claim 2 (rupturable diaphragm + spring-driven piercing plunger + removable retaining/pull pin) is disclosed. Strictly, because claim 2 incorporates claim 1 and thus the quadrilateral-coil limitation, Seeler alone cannot anticipate claim 2 as a whole; it anticipates the claim‑2 improvement limitations, and the combination could support a § 103 rejection.

3) US 3,292,821 — Cowley, "Coin operated oxygen dispenser" (coiled tubular vessel)

• Full citation: US 3,292,821, filed 1965‑07‑15 (Ser. No. 472,088), granted 1966‑12‑20, John James Cowley. (Also indexed at FPO: https://www.freepatentsonline.com/[3292821](/patent/3292821).html.)
• Description: An oxygen vending machine whose pressure vessel (20) "comprises a single container tube wound about itself in a spiral form to provide a greatly elongated continuous tubular pressure container capable of withstanding very high internal pressures," expressly for avoiding "the destructive effects of an explosion." The specification cross-references the inventor's earlier Ser. No. 450,325, "Tubular Pressure Vessel" (filed 1965‑04‑23). Downstream: an expansion chamber (21) for unit-volume metering, solenoid valves (23, 25) controlling flow, a dispensing head/needle, and a one‑way flow control valve (44) that "permit[s] flow of oxygen outwardly but … prevent[s] reverse flow of air."
• Potentially relevant claim(s): Preamble of claim 1 — specifically the "hollow coil of high pressure tubing for containing a breathable gas at high pressure" and the "means for permitting gas flow out of … and inhibiting gas flow into" (check valve 44), plus pressure regulation / metering of the gas delivered to the user.
• § 102 assessment: This is the closest § 102(b) art to the coil-reservoir concept at the heart of claim 1's preamble, and its thin-walled, coiled, explosion-tolerant tubular vessel is the very idea the patent's background touts (the patent notes that a coiled tube tends to leak slowly rather than jet, and its own test with a .308 round illustrates the point). It does not disclose a flexible head bag with a transparent front, provision of gas into a hood at the nape of the neck, or the quadrilateral inner+outer coil geometry around a rectangular regulator/actuator that constitutes the claimed improvement. So it anticipates much of the preamble, not claim 1 as a whole.

Corroboration (flagged as foreign-proceeding context, not record art): A Canadian Patent Appeal Board decision surfaced in my searches that analyzes an apparatus essentially identical to the US 3762407 claim 1 — describing "the Cowley patents" as disclosing "a breathing apparatus with a hollow coil … with a manometer [gauge] inside the coil," a regulator inside the coil, and an actuating device inside the coil that on actuation produces substantially instantaneous gas supply; the decision then quotes a rejected claim closely mirroring claim 1 here. Source: https://brevets-decisions-patents.opic-cipo.gc.ca/pab-cab/p/fr/[466788](/patent/466788)/1/document.do. This is corroborative only — it is a foreign counterpart proceeding, and the "Cowley patents" referred to appear to be US 3,292,821 and US 3,505,997. Treat it as a lead, not proof of the U.S. examiner's reasoning.

4) US 3,505,997 — "Oxygen breathing apparatus" (coil-in-container with break-to-actuate release)

• Full citation: US 3,505,997, filed 1967‑03‑31, granted 1970‑04‑14, assignee recorded as Abbott Laboratories (the Google Patents citation row shows the Abbott assignee; a separate patent-index listing gives the inventor as John James Cowley — I could not independently confirm this inventor attribution before my search budget ended, so treat the inventorship as unverified).
• Description: A small, hermetically packaged emergency oxygen inhalator/resuscitator. Its high-pressure oxygen container is a length of tubing (10) wound as a coil fitted within a generally cylindrical container (11) — directly addressing the problem of a "completely safe and reliable high pressure oxygen container … safe from leakage or explosion." Gas leaves through a capillary tube (16) with a metering jet (17) of only ~0.002–0.004 in. for flow limiting/pressure reduction; a weakened closed neck (19) is fractured to release the gas; a demand valve and expansion bag (27) regulate delivery to a face mask (15); a one‑way flap valve (29) permits air entry; and release is triggered by removing a cardboard disc (40) that frees a spring arm (35) carrying a retaining pin (39), causing the arm to break the frangible neck; the unit is stored in a hermetic wrapper (42).
• Potentially relevant claim(s): Preamble of claim 1 (coiled high-pressure tubing reservoir, flow limiting/pressure reduction, mask, one-way valve); claim 2 (a frangible/seal-breaking pressure barrier with a retaining pin holding the release means until deliberately freed); and generally the "compact package, instantly usable after storage" concept.
• § 102 assessment: A strong § 102(b) reference for the coil-reservoir + flow-limiting orifice + one-way valve + retain-to-arm preamble concepts. It omits the flexible transparent-front hood, nape-of-neck mounting, a plunger with a perforating tip (it fractures a weakened neck, not a spring-driven piercing needle — a meaningful structural difference for claim 2), and again the quadrilateral coil improvement. No claim is fully anticipated by it alone.

5) US 3,633,596 — Gerber, "Diaphragm valve" (rupture disc + hollow knife)

• Full citation: US 3,633,596, filed 1970‑07‑23 (Ser. No. 57,710), granted 1972‑01‑11, inventor Robert L. Gerber, assignee The United States of America as represented by the Secretary of the Navy.
• Description: A diaphragm valve that seals a chamber using a rupture disc (11), a hollow knife member held adjacent to the disc by a power spring / spring retainer, and a bellows motor; when initiated (electrically or manually with the power spring driving the knife), the knife is driven through the disc to open a fluid passageway through the hollow knife body — expressly claimed for "any situation requiring both a sealing and seal-rupturing mechanism" that must "maintain a leakproof seal for an indefinite period of time."
• Potentially relevant claim(s): Claim 2 — the diaphragm/seal + perforating element + spring-driven actuation sub-combination (though its "retaining pin" analogue is the spring retainer/bellows, not a pull pin).
• § 102 assessment: Time-critical, as noted: granted after the parent's 1971‑05‑10 filing date, so it is not § 102(b) art; it can only be § 102(e)/§ 103 art as of its 1970‑07‑23 filing date. On substance it corroborates that a spring-urged knife/plunger into a rupture disc as a long-term seal + instant-release mechanism was known, but its structure (hollow knife; no removable retaining pin; bellows-motor release) differs from claim 2's plunger/pin arrangement, and it shares none of claim 1's bag/coil/quadrilateral features.

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Synthesis — what each reference can and cannot do

Claim 1 (independent, Jepson). No single cited reference discloses the complete claimed invention, and none discloses the point of novelty — the outer quadrilateral coil + concentric inner quadrilateral coil closely conforming to a substantially rectangular regulator/actuator to minimize volume. Expected roles:

• US 3,292,821 (Cowley) and US 3,505,997 supply the admitted-prior-art preamble element of a hollow coil of high-pressure tubing holding breathable gas, with flow limiting and a one-way valve.
• US 456,687 (Bader) supplies the transparent-front breathing enclosure with stored gas, gauge, and exhalation outlet.
• None reaches the quadrilateral-coil improvement, so claim 1 as a whole appears not anticipated by the cited art; if the examiner relied on these, it would most plausibly have been a § 103 combination, or a § 102(b) attack limited to the admitted preamble. (Again: I could not obtain the actual rejection to confirm.)

Claim 2 (diaphragm + spring-biased perforating plunger + removable retaining pin). The strongest single-reference case in the whole set:

• US 2,697,538 (Seeler) discloses every functional element of claim 2 (imperforate sealing disk; spring-urged plunger with piercing point; mounting for movement; safety pin 39 + pull cord as the removable retaining pin). Best § 102(b) reference for claim 2's added limitations.
• US 3,633,596 (Gerber) is a secondary § 102(e)/§ 103 reference for the rupture-disc-plus-actuator concept.
• Because claim 2 depends from claim 1, neither anticipates claim 2 as an integrated whole; they target the added limitations.

Claim 3 (pressure gauge + pressure-containing fill valve, accessible from the ends of the hollow cylinder).

• US 456,687 (gauge D + regulable charging/valve E) and US 2,697,538 (gauge 9 threaded into the housing) disclose gauges in gas systems; US 3,292,821 / 3,505,997 disclose charging/fill and flow-control hardware on a coiled vessel. The "all accessible from the ends of the hollow cylinder" packaging limitation is not clearly disclosed by any single reference → most likely a § 103 combination rather than straight anticipation.

Claim 4 (transparent portion is flexible).

• US 456,687 (Bader) shows a transparent viewing portion but of rigid glass in a metal frame — the opposite of "flexible." None of the cited references clearly discloses a flexible transparent viewing portion as such (the flexible-bag/transparent concept is part of the admitted preamble here). So claim 4's added limitation is not anticipated by the cited art.

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Honest limitations / flags

1. No Office action retrieved. The examiner's actual grounds (anticipation vs. obviousness, and which claim each reference was applied against) are not in the material I was given; my claim mapping is inference from the granted text. For the authoritative rejection record, pull the USPTO PatentCenter file wrapper image PDF for application Ser. No. 247,107 and its parent Ser. No. 141,781.
2. Inventorship of US 3,505,997 is unverified. The citation list shows the Abbott Lab assignee but no inventor; a third-party index attributed it to John James Cowley. I could not confirm before reaching my search limit.
3. US 456,687 title. The citation row displays "William bader" (the patentee) rather than a formal title; treat the "smoke-protection headpiece" description as taken from the specification text, not a formal title.
4. "Cited By" and "Similar Documents" are not prior art. The 40–66 post-1973 citing patents (e.g., US 3,976,063 Bendix; US 4,221,216/US 4,233,970 Robertshaw; US 4,629,571 Lockheed) and the sibling US 3,762,604 post-date this patent and cannot be § 102 art against it.
5. Foreign-proceeding corroboration flagged as such (Canadian Appeal Board decision referencing "the Cowley patents") — useful lead, not part of the U.S. prosecution record.
6. Typographical artifacts in the scanned text (e.g., "contanst," "vlave," "conning") are OCR errors and should not be read as technical terms — consistent with the earlier summary's flag #2.

Bottom line: Of the five examiner-cited references, US 3,292,821 (Cowley) and US 3,505,997 are the most relevant to the coil-reservoir preamble of claim 1, and US 2,697,538 (Seeler) is the most relevant to claim 2's diaphragm/piercing-plunger/retaining-pin sub-combination. US 456,687 (Bader) supports the transparent-front-bag preamble and gauge concepts. US 3,633,596 (Gerber) is a § 102(e)-only (post-parent-filing) reference for the rupture-disc actuator concept. No single cited reference anticipates claim 1 as a whole — least of all the quadrilateral inner/outer coil improvement, which none of them discloses.

I'll research the cited prior-art references before analyzing obviousness.

Let me examine additional related prior art identified in the record.

Obviousness Analysis — US Patent 3762407 A under 35 U.S.C. § 103

Builds on the prior "Patent summary" and "Litigation summary" sections; does not repeat bibliographic data, the claim-by-claim summary, or the JP 3762407 disambiguation, all of which remain as stated there.

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0. Scope, framework, and what I actually verified

Legal framework applied. I evaluate under Graham v. John Deere Co., 383 U.S. 1 (1966) (scope/content of claims; differences from prior art; level of ordinary skill; secondary considerations), as refined by KSR Int'l Co. v. Teleflex Inc., 550 U.S. 398 (2007) (expansive motivation-to-combine; "obvious to try"; "predictable variation"; design choice; "a court must ask whether the improvement is more than the predictable use of prior art elements according to their established functions").

Prior art considered. The record's "Patent Citations (5)" — all marked "cited by examiner" — plus the closely-related documents appearing in the record's "Similar Documents" list that predate the 1971 parent filing:

Key evidentiary find. A Canadian Patent Appeal Board decision dated 18 December 1975 (file 466788) — refusing claims of the counterpart/related Canadian application — contains express factual findings that bear directly on this patent family. The decision states: "It is observed that the rectangular shaped reservoir coils are shown by Alderfer, and the circular cylinder shaped reservoir coils are shown by Cowley," and "we are satisfied … that there is no unobvious functional connotation for that particular shape." (Source: https://brevets-decisions-patents.opic-cipo.gc.ca/pab-cab/p/en/466788/1/document.do)

Cross-reference / contradiction flag: Nothing in the previously generated sections contradicts the analysis below. One naming discrepancy inside a single source must be flagged literally per my operating rules: the English text of the Canadian decision reads "Claim 1 of Cowley (3,502,075)" while the French text of the same document reads "La revendication 1 de Cogley (3,502,075)." I do not auto-correct either spelling; I treat US 3,502,075 as the reference intended, consistent with the record's own "Similar Documents" entry (US3502075A, 1970-03-24, "Portable resuscitator apparatus").

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1. Level of ordinary skill in the art (Graham factor 3)

A PHOSITA at the 1971–1972 effective filing date (parent Ser. No. 141,781 filed 1971-05-10) would be a mechanical design engineer (or a small team) with roughly 2–4 years' experience in portable emergency breathing apparatus, high-pressure gas containment (2,000–5,000 psi), and miniature pressure-regulator/valve design, working from the published literature of suppliers such as Abbott, Cowley/Air-Ports, Seeler, and Bendix. The art is a well-developed, crowded mechanical arts field — an important KSR consideration, because in a crowded field the incentive to combine known elements and to make small packaging improvements is high.

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2. Claim 1 — the independent claim (Jepson form)

2.1 The preamble is a statutory admission of prior art

Claim 1 opens: "In a survival support device comprising: [bag] … [one-way means] … [hollow coil of high pressure tubing] … [regulator means within the coil] … [actuator means within the coil] … [support means … against the nape of a user's neck], the improvement wherein …"

This is classic Jepson format (37 C.F.R. § 1.75(e)). The preamble elements are therefore admitted prior art, and the patentability question collapses to the "improvement wherein" clause: the outer quadrilateral coil + concentric inner quadrilateral coil closely conforming to a substantially rectangular regulator/actuator, "whereby the total volume of the gas supply is minimized."

That is a very narrow remaining delta, and the preamble is independently corroborated by the art (§2.2).

2.2 The admitted prior-art combination is expressly disclosed by Cowley and Abbott

The Canadian Board's recitation of the refused counterpart claim is worth quoting because it is effectively claim 1's preamble verbatim:

"A compact breathable gas supply comprising a hollow coil of pressure resistant tubing for containing breathable gas at high pressure … regulator means mounted within the hollow space of the coil … and actuator means mounted within the hollow space of the coil and operable by an operator for substantially instantly actuating the gas supply."

The Board held that Cowley discloses "broadly the same elements, functionally interrelated in the same manner to produce substantially the same results," and that "[a] pressure gauge is located within the hollow coil with means for controlling the output of the gas to a patient."

Supporting details retrieved from the references:

• US 3,292,821 (Cowley): "Container 20 comprises a single container tube wound about itself in a spiral form … to provide a greatly elongated continuous tubular pressure container capable of withstanding very high internal pressures and having a relatively thin walled structure … avoiding the destructive effects of an explosion if it should take place." Also discloses a one-way flow control valve 44 ("to permit flow of oxygen outwardly but to prevent reverse flow") and an expansion chamber. (https://patents.google.com/patent/US3292821; PDF at https://patentimages.storage.googleapis.com/d4/cc/b1/902ff3d20456f6/US3292821.pdf)
• US 3,502,075 (Cowley): pressure vessel = "a length of high pressure resistant tubing" enclosed in a donut-shaped jacket, feeding a capillary tube, pressure gauge, on/off tap, and breathing mask with a non-return flap valve. (https://patents.google.com/patent/US3502075)
• US 3,505,997 (Abbott): high-pressure oxygen in a coil of tube 10 inside cylindrical container 11; capillary tube 16 with metering jet 17 (2–4 thousandths inch) for flow limitation; a weakened neck 19 that is fractured to initiate flow; a one-way flap valve 29; an expansion bag 27; and the act of opening the wrapper automatically extends the face mask and breaks the seal. (https://patents.google.com/patent/US3505997)

Result: every element of claim 1's preamble — coil-of-tubing high-pressure reservoir, regulator inside the coil, actuator inside the coil, one-way outflow means — is in the prior art, as the examiner who cited Cowley, Abbott, Seeler, Gerber and Bader evidently appreciated.

2.3 The sole improvement is a design choice with no unobvious functional connotation

The improvement (quadrilateral outer coil + quadrilateral inner coil wrapped around a rectangular regulator/actuator "whereby the total volume … is minimized") is rendered obvious by Cowley in view of Alderfer, and I can cite a patent office's own finding to that effect:

Why a PHOSITA would combine. A worker seeking to shrink a body-worn 10-minute breathing set (the stated purpose in the '407 specification: wearability on the belt, at the nape, under a helmet) has an obvious and finite set of packaging options for a wound-tubing reservoir. One textbook option is conforming the winding to the shape of the hardware it encloses. Doing so for a box-shaped regulator body yields a squared coil, and using two winding layers (a "double helical coil," as the '407 specification itself calls FIG. 3) yields concentric inner and outer coils. This is KSR's "predictable variation" and "design choice" rationale, reinforced by the fact that the number of coils and the coil cross-section are non-functional packaging variables the specification itself treats as adjustable ("three concentric coils of tubing can be employed … to provide greater storage capability … or … the total length … can be decreased as the diameter is increased without change in the operating time").

The "whereby" clause adds no weight. "Whereby the total volume of the gas supply is minimized" states the intended result of the recited structure; under In re Vickers / Texas Instruments v. ITC line of authority, a whereby clause is not given patentable weight unless it changes the scope of the claimed step.

2.4 Claim 1 conclusion

Claim 1 would have been obvious under § 103 over Cowley (US 3,292,821 and/or US 3,502,075) in view of Alderfer, and further in view of Abbott (US 3,505,997) and/or the Jepson preamble admission, for the packaging of a coiled-tubing reservoir into concentric quadrilateral coils around a rectangular control mechanism. The strongest single sentence in support is the Canadian Board's: the rectangular coil shape has "no unobvious functional connotation."

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3. Claim 2 — diaphragm + spring-driven perforating plunger + retaining pin

Claim 2 elements vs. Seeler, US 2,697,538

Seeler alone is close to a § 102 anticipation of the substance of claim 2, and at minimum a § 103 render-obvious — the only arguable distinction is that Seeler's retention is a latch + pull cord + safety pin rather than a pin passing through a transverse hole in the plunger. Substituting a shearable/captive pin for a latch-and-cord release is the epitome of a predictable mechanical variation; and Seeler itself already uses a removable pin as the safety.

Corroborating references for claim 2

• US 3,633,596 (Gerber / Navy "Diaphragm valve"): "a rupture disc, a hollow knife, a power spring, a power spring retainer and a bellows motor. The hollow knife is positioned by the power spring retainer adjacent to the rupture disc … provid[ing] the force, when initiated, to force the knife into the disc to rupture it thus permitting air to fill the chamber through the hollow knife body … The device may also be activated manually with the power spring providing the driving force to the knife." (https://patents.google.com/patent/[US3633596A](/patent/US3633596A)) — This is the '407's spring-driven, pin-retained plunger with a gas-relief slot 67 through the tip almost element-for-element. Timing note: Gerber was filed 1970-07-23 (before the 1971-05-10 parent filing) and issued 1972-01-11 → available as pre-AIA § 102(e) art as of its filing date, and the examiner cited it as such.
• US 3,505,997 (Abbott): spring arm 35 with upstanding retaining pin 39 engaging a cardboard disc 40 (with tag 41); "Removal of cardboard disc 40 will release arm 35 and spring 36 will thereupon swing arm 35 … breaking closed end 18" — i.e., spring-biased rupturing member + removable retainer in a breathing apparatus context. Directly on point for the "removable retaining pin" limitation.

Motivation to combine

The motivation is stated in Seeler itself and in the '407 specification: a survivable device must sit for "long periods of time without recharging" yet actuate "rapidly and reliably on a moment's notice." A frangible/rupturable diaphragm with a spring-driven piercer achieves both, because the piercer is not exposed to full line pressure during storage. The '407 specification says so expressly: "During static conditions before the device is actuated, there is no pressure across the O-ring 57 since the gas pressure is retained by the diaphragm seal 39." A PHOSITA improving shelf life and reducing seal leakage in a stored high-pressure breathing set would predictably look to the rupture-disk-plus-piercer architecture already used in aircraft oxygen regulators (Seeler) and in Navy diaphragm valves (Gerber).

Claim 2 would have been obvious over Seeler alone, or Seeler in view of Gerber, or Seeler in view of Abbott.

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4. Claim 3 — pressure gauge + pressure-containing fill valve, all accessible from the cylinder ends

Analysis. Claim 3 adds instrumentation and refill-accessibility to an admitted-prior-art instrumented gas supply. Placing a gauge and a fill port at the ends of a cylindrical container so they can be reached without disassembly is an accessibility/ergonomic design choice, driven by a self-evident motivation (field inspection and topping-up of a stored emergency device — the '407 spec. says the gauge exists so that "[i]f the gauge indicates that the pressure has dropped due to slow leakage … it is only necessary to reopen the fill valve to bring the pressure back up"). KSR: "the predictable use of prior art elements according to their established functions."

Claim 3 would have been obvious over Cowley US 3,502,075 in view of Seeler, or over the Jepson preamble admission combined with any of the cited gauged gas supplies.

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5. Claim 4 — the transparent portion is flexible

Claim 4 is a one-line limitation: "the transparent portion of the bag is flexible." The record's own 1973 description already characterizes the hood front portion 14 as "transparent plastic" and the hood as a whole of "flexible plastic" film that is wrapped around the canister for storage. Abbott's mask is "flexible rubber or plastic"; Cowley's resuscitator mask is likewise flexible. A flexible, transparent polymer film for a foldable emergency head covering is the only practical choice for a device whose stated requirement is to be folded/wrapped into a package the size of the canister and carried on a belt.

Claim 4 would have been obvious as a mere recitation of an inherent/expected property of the flexible plastic bag already recited in claim 1's preamble, over Cowley, Abbott, and the knowledge of transparent flexible plastic sheet and film (the record's own keyword extraction shows "plastic film" and "flexible plastic" as description terms).

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6. Consolidated combination table

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7. Weaknesses, counterarguments, and gaps a challenger (or the patentee) would raise

For the patentee (rebuttals a § 103 challenge must overcome):

1. Secondary considerations. Commercial success, long-felt need, and copying are the classic Graham rebuttals. Lear Siegler marketed the device; the sales-success record may be probative — but the nexus is weak because success likely traces to the hood-at-the-nape/10-minute/3½-pound concept (all in the admitted preamble), not to the quadrilateral-coil improvement that is the only claimed delta. Under KSR/Wm. Wrigley, an un-nexused success argument fails.
2. Criticality of the geometric arrangement. The patentee could argue that the specific inner quadrilateral coil closely conforming to the rectangular body is critical rather than arbitrary. This is precisely the argument the Canadian Board rejected ("no unobvious functional connotation"), so it is a losing argument on the record — but note the Board's decision was under the pre-1989 Canadian "patentable advance" standard, not US § 103, so it is persuasive, not binding.
3. Number-specific results. The specification's genuinely impressive numbers — single-stage regulation from ~5,000 psi inlet down to 250 psi with outlet held at 200 psi ±20 psi, chamber 79 under 0.01 in³, orifice 83 of 0.01 in — are not claimed and therefore cannot support patentability. Even if they were, unsupported "criticality" of numerical ranges is a hard argument.

Unresolved gaps I must disclose rather than paper over:

• Alderfer is unverified. The Canadian decision names "Alderfer" without a patent number in the text I retrieved. I could not identify its number, jurisdiction, or publication date, so I cannot confirm it is pre-1971 § 102(b) art against the '407 parent. This is the single most important verification item for a formal obviousness challenge; the combination's strength rises or falls with Alderfer's date and content. My earlier search steps were exhausted before I could resolve it.
• US 456,687 (Bader) is unverified. I retrieved no title, disclosure, or content for it; my search on that number returned nothing usable. I therefore assign it no weight beyond noting the examiner cited it (likely as a very early disclosure of a coiled/ruptured-seal fluid container, but I cannot confirm that).
• US 3,491,752 ("Breathing apparatus," 1970-01-27) appears in the record's "Similar Documents," which would place it in the relevant window, but I did not retrieve its disclosure and make no claim about it.
• Transparent-hood reference gap. I did not locate a pre-1971 reference expressly disclosing a transparent head-covering hood. This does not defeat the analysis, because the hood element sits in the Jepson preamble (admitted prior art); but if the preamble admission were successfully contested, the hood element would need to be separately supplied, and I cannot do so from the retrieved record.

Drafting defects worth noting (they affect how obviousness is argued, and I flag rather than correct them):

• Antecedent basis. Claim 1 recites "a hollow coil of high pressure tubing" but then says the actuator connects the regulator to "the reservoir means," which is never antecedently introduced. Claim 3 then refers to "the ends of the hollow cylinder," likewise never introduced in claim 1. These loose antecedent bases make the claim's scope ambiguous — which, for § 103 purposes, cuts against the patentee, because ambiguous limits are construed narrowly and narrow limits are more easily met.
• Claim-set completeness. As I noted in the prior "Patent summary," the rendered grant text contains narrative fragments of claims interleaved with the claim list; anyone relying on the exact scope should confirm the claim set against the USPTO PatentCenter image PDF.
• Copending sibling is not prior art. US 3,762,604 ("Survival support device," same issue date, same family) shares the '407 parent and is not "by another," so it is not § 102(e) art against '407 — the two are companion divisions.

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8. Bottom line

On the record available, all four claims of US 3762407 A are vulnerable to a § 103 obviousness attack:

• Claim 1 is a Jepson claim whose entire preamble is admitted and independently disclosed by Cowley (coil reservoir with regulator, actuator, and gauge mounted inside the hollow coil) and Abbott (coiled high-pressure oxygen tube, metering jet, one-way valve, break-seal). Its only improvement — concentric quadrilateral coils around a rectangular regulator/actuator — is rendered obvious by Cowley in view of Alderfer, with the motivation being the art's own express goal of compactness/weight reduction, and with a patent office's express finding that the rectangular coil "shape" has "no unobvious functional connotation."
• Claim 2 is substantially met by Seeler alone (rupturable sealing disk + pointed spring plunger + pull-cord release + safety pin + O-ring seal + pressure gauge), and fully met by Seeler in view of Gerber (rupture disc + hollow knife + power spring + retainer) or Abbott (spring arm + retaining pin + removable retainer).
• Claim 3 is obvious over Cowley US 3,502,075 (gauge within the coil) in view of Seeler and/or Abbott.
• Claim 4 recites an inherent/expected property of the flexible transparent plastic already in claim 1.

Highest-value next steps for a formal challenge: (1) verify Alderfer's number, date, and disclosure; (2) pull the USPTO PatentCenter image PDF to confirm the full claim set and the exact wording of claim 1's preamble admission; (3) run PACER/CourtListener/Unified Patents directly, since my earlier "no litigation" conclusion was a search-based negative, not an authoritative docket check.