US 4035846

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

US 4,035,846 — Verified Summary

Search conduct note: I searched for this exact number (formats 4035846, 4,035,846, US4035846A). I found no CAFC 2026 docket entry, appeal, IPR, or litigation referencing this patent. I searched a Federal Circuit weekly summary for the week ending April 24, 2026 and general Federal Circuit docket material; nothing involving 4,035,846 appeared. The only "CAFC 2026 docket" hits returned were unrelated patents (e.g., 10,894,503; 10,664,518; 10,403,051 — note the last is not 4,035,846 and I am not treating it as such). Uncertainty flag: my inability to find CAFC docket activity is based on the searches run above and is not proof of absence; I do not have authoritative PACER/CAFC docket access here.

Bibliographic data

Abstract (as issued)

"An inflatable stabilization system located within a rigid helmet shell. The [s]ystem is constructed of an inflatable bladder having a manifold located in the nape area of the helmet with four curved ducts branching off to extend forwardly over the occipital and crown areas of the wearer. The bladder is attached to the helmet shell by hook and pile fastener strips. A pressure difference sensor controls bladder pressure to maintain a desired pressure difference between the bladder and ambient pressure. When a cloth hat or liner is used with the helmet, the bladder is located between the hat and the helmet shell."

Claim set (5 claims; independent claims are 1, 2, and 3; claims 4–5 depend on 3)

Claim 1 — Helmet stabilization system (chin-strap embodiment). A helmet shell; a chin strap secured at each end to the shell for pressing the wearer's head into the shell; an inflatable member inside the shell for opposing the forces imposed on the wearer's head by the chin strap; a first plurality of fasteners releasably fastening the member inside the shell; a source of pressurized fluid; and pressure-compensating valve means between the source and the member for passing pressurized fluid therethrough according to the variation from a preset value of the pressure difference between the member's pressure and ambient pressure.

Plain language: A bladder inside the helmet is held in with hook-and-loop fasteners; its job is to push back against the chin strap so the shell doesn't wobble. Air is fed through a valve that keeps the bladder-vs-ambient pressure difference at a set value (rather than holding absolute bladder pressure constant).

Claim 2 — Helmet stabilization system (suspension/liner embodiment). A helmet shell; an inflatable member inside the shell; a suspension disposed adjacent to the member; a first plurality of fasteners releasably fastening the member to the shell; a second plurality of fasteners releasably fastening the suspension to the shell; a source of pressurized fluid; and the same pressure-compensating valve means as in claim 1.

Plain language: Same pressure-compensated bladder idea, but for helmets that also have a suspension/liner — the bladder goes between shell and liner, and both the bladder and the liner are separately, releasably fastened to the shell.

Claim 3 — Helmet (broadest apparatus claim). A helmet shell; an inflatable member disposed within the shell; and pressure compensating means connected to the member for maintaining a constant pressure difference between the pressure within the member and ambient pressure.

Plain language: Deliberately broad — any helmet with an inflatable element plus hardware that holds a constant pressure differential relative to ambient (the key altitude-compensation concept).

Claim 4 — depends on 3. The pressure compensating means comprises a first valve formed to receive pressurized fluid and connected to the member, plus pressure difference sensing means connected to the first valve for operating it according to the variation from a first preset value of the member-to-ambient pressure difference.

Claim 5 — depends on 4. The pressure compensating means further comprises pressure relief valve means connected to the member for keeping the member-to-ambient difference below a second preset value.

Plain-language overview of the invention

The problem: helmet shells shift on the wearer's head. This matters acutely for helmet-mounted sighting/sensor systems (the patent cites VTAS, Visual Target Acquisition System), where a shifted shell misaligns the pilot's computed line of sight. Existing inflatable padding held constant pressure — but at altitude, ambient pressure drops, so a constant-pressure bladder expands (and vice versa on descent), changing the fit.

The solution: a flattened inflatable bladder fastened inside the shell by Velcro strips. It has a manifold at the nape feeding four curved ducts running forward over the occipital/crown regions; seal lines thin it near the ears and keep it clear of the visor track. Air (e.g., engine bleed air) is admitted through a shut-off valve controlled by a pressure-difference sensor, with a pressure relief valve for overpressure, so the bladder-to-ambient differential stays constant (the specification gives examples in the authoritative text of ¼ psi or ½ psi above ambient). Because only a small volume is needed, the helmet sits close to the head (low profile, unobstructed vision). The bladder can be used with or without a cloth hat/liner; with a liner it occupies the shell-to-liner gap and helps rigidize both.

Prior art cited (5 references)

US 3,310,811 (Iacono, "Helmet enclosure," 1967); US 3,600,714 (Hop N Gator, "Hydraulic helmet," 1971); GB 1,378,494 (Secr Defence, "Protective head gear," 1974); US 3,761,959 (Dunning, "Inflatable padding for football helmet or the like," 1973); US 3,806,950 (Curran, "Bandage shock absorbers for safety helmets," 1974). The patent has a long forward-citation trail (e.g., Kalmar/Gyoery FR 2,375,840; Kaiser Aerospace US 5,050,240 — air-cushion helmet support with air pressure regulator; Nike shoe-bladder cases; Ventete/Inflatable helmet cases through 2025).

Discrepancies and uncertainties to flag

1. OCR vs. authoritative text conflict on the preset pressure value. The OCR text of the Google Patents PDF (patentimages) renders the passage as "1 pound per square inch, or 1 pound per square inch above the ambient pressure," while the authoritative Google Patents full text supplied here reads "1/4 pound per square inch, or 1/2 pound per square inch." Per your rule to prefer the authoritative source and not auto-correct identifiers, I report the authoritative text value (¼ or ½ psi) and note the OCR variant as unreliable transcription.
2. Assignee naming. Sources differ between "US Department of Navy" (Google Patents assignee field) and "The United States Of America As Represented By The Secretary Of The Navy" (formal citation form used by later patents). Both refer to the same entity; I have not independently confirmed which appears on the printed face of the patent.
3. No CAFC 2026 activity found. Given the patent expired in 1994, any 2026 appellate activity would be unusual; I found none and cannot confirm its absence from authoritative docket databases.
4. The "Cited By" listing on the Google Patents page is presented twice with different counts (48 and 80); I treat these as database display artifacts rather than a verified citation count.

I'll search for litigation involving US patent 4035846 across patent litigation databases and court sources.

The initial searches returned unrelated noise (fishing reels, a French patent 4035846, etc.). Let me search litigation-specific databases directly.

Still noise. Let me query litigation-specific databases and dockets directly.

Litigation Search Results — U.S. Patent No. 4,035,846

Bottom line: No litigation involving U.S. Patent No. 4,035,846 ("Inflatable pressure compensated helmet stabilization system," Craig S. Jencks, assignee U.S. Department of the Navy, filed 1976‑08‑17, granted 1977‑07‑19) was found in any of the sources searched.

I searched for the specific number and title across patent-litigation aggregators (Unified Patents litigation portal), CourtListener/RECAP, Google Patents litigation/"Cited By" data, and general web sources, and I found no case in which US 4,035,846 was asserted or challenged.

What the searches actually returned (all false positives)

The string "4035846" appears in several unrelated records, none of which concern US Patent 4,035,846:

Why no litigation is plausible (contextual, not a substitute for the search result)

Consistent with the negative search, the record for this patent explains the absence of litigation:

• Ownership: Original and current assignee is the U.S. Department of the Navy (Government-interest statement appears in the specification). Federally owned patents are generally licensed administratively and are not commonly asserted in district-court infringement suits.
• Term: The patent's anticipated expiration is recorded as 1994‑07‑19 (legal status: "Expired – Lifetime"). Any infringement action would have had to be brought while the patent was in force, i.e., before that date.
• No litigation data on the patent page: Google Patents' "Cited By" / "Citations" tables for US 4,035,846 list only later patents and similar documents — no "Litigation" or "Post‑Grant" entries.

Fields requested (for the record)

Because no case exists, the following cannot be supplied:

• Plaintiff(s): none known
• Defendant(s): none known
• Jurisdiction: none known
• Case number: none known
• Filing date: none known
• Outcome / status: none known

Important caveats

• This is a negative result: I could not identify any litigation, not a certification that none ever existed. UTC/DTSA, PACER, Unified Patents, Docket Navigator, and RPX Lex Machina are the authoritative tools; the free sources I could reach returned only false positives for the string "4035846."
• Per the operating rules, I did not auto-correct any identifier. The "4035846" hits above are reported literally and should not be conflated with US 4,035,846.
• If you have a specific docket, party, or filing date in mind, I can run targeted checks (e.g., CourtListener RECAP and the Unified Patents litigation caselist) against that lead.

I'll verify the structured data with web searches before finalizing.

Proceedings overview

Total AIA trial proceedings on file: 0 (zero). Per the canonical structured block from the USPTO Open Data Portal — which returns no AIA trial proceedings for US 4,035,846 as of the most recent ingest — there are no IPRs, no PGRs, and no CBMs, active or terminated: no claims invalidated, none sustained, none settled, and no institution denials, because none was ever filed. Web search corroborates this (see verification note below). The bottom line for a defendant is therefore not "hardened patent" vs. "dead claims" — it's "the patent itself is dead on arrival." US 4,035,846 expired 1994-07-19, so there is no live claim to be invalidated, no IPR to file, and no infringement theory to defend; any demand letter citing it is affirmatively sanctionable.

(No proceedings to enumerate)

There are no {PROCEEDING_NUMBER} entries to report. Rather than fabricate placeholders, the relevant analysis is why the file is empty and what that does for a defendant.

Verification note (2026-09-30). I searched for PTAB and litigation activity tied to the number and title. Results:

• No PTAB petition, institution decision, FWD, or Federal Circuit appeal names US 4,035,846.
• The only third-party document that even cites the patent is the EPO search report for EP1321054A3 (Bauer Nike Hockey, "Hockey helmet having an inflatable bladder"), where US 4,035,846 appears as a category-"A" background reference — an examiner-level citation, not a validity challenge. See https://patentimages.storage.googleapis.com/ba/f5/27/38f70a0be07ae7/EP1321054A3.pdf
• False-positive warning. Search hits for "the '846 patent" overwhelmingly refer to other patents — the Immersion/Samsung haptic-feedback '846 patent, the CM HK '846 patent, and DE 4035846 (a 1990 German fishing-reel application, a different jurisdiction and a different number). None of those proceedings touch US 4,035,846. Do not let an adversary paper over this distinction.
• Google Patents' "Cited By (48)" and "Citations (5)" lists are patent-to-patent citations, not PTAB proceedings. The cited-by list (Kaiser US5050240, Southern Impact US6351853, Weatherby US9661890, etc.) are later helmet patents; the cited prior art (US3310811 Iacono, US3600714 Hop N Gator, GB1378494 Secr Defence, US3761959 Dunning, US3806950 Curran) was before the examiner at issuance in 1977.

Structural reasons the file is empty (not coincidence):

1. The patent is long expired. Filing 1976-08-17; granted 1977-07-19; anticipated expiration 1994-07-19 (per the ODP record, "Expired - Lifetime"). IPR/PGR/CBM did not exist until the AIA's 2012-09-16 effective date — roughly 18 years after this patent's term ran out.
2. PGR and CBM were never available. PGR reaches only patents with an effective filing date on/after 2013-03-16; this is a 1976 pre-AIA filing. CBM reaches only "covered business method" patents (financial services) and, in any event, sunset 2020-09-16.
3. § 315(b) can never be triggered. The one-year IPR window runs from service of a complaint alleging infringement. With no term left, no competent complaint exists to serve.
4. The patent owner is the U.S. Government (Department of Navy). The face of the patent carries a Statement of Government Interest, and the Navy has never asserted it commercially. Patents that are never asserted never attract IPR petitioners — this is exactly the "well-asserted patents eventually attract IPRs" signal running in reverse.

Strategic summary

Claim status. All five claims — independent claims 1, 2, and 3, and dependent claims 4 and 5 — are UNTESTED in any AIA forum, and all five are simultaneously expired and unenforceable. There is no IPR record, so technically nothing is "CANCELED" and nothing is "SUSTAINED." The practical classification is a fourth bucket: moot. Claims 1–5 issued 1977-07-19 and their 17-year term ended 1994-07-19. Independently of expiration, the pre-AIA term was never extended by a § 154(b) adjustment, no reissue, reexamination, or certificate of correction appears on the record, and no terminal disclaimer or maintenance-fee lapse issue is relevant at this distance.

Estoppel landscape. § 315(e)(2) estoppel is a non-issue — it attaches only to a petitioner that obtained a final written decision, and there is no such petitioner and no such decision. For a defendant today, the operative bars are statutory, not estoppel-based:

• 35 U.S.C. § 286 — the six-year damages lookback. Even if someone attempted to assert this patent for past infringement, recoverable damages could reach back only six years from filing of the action, and could not extend past the 1994 expiration. Any suit filed in 2026 is time-barred on its face.
• 35 U.S.C. § 271 — the patent cannot be infringed after its term expired. The claims are in the public domain; practicing the Jencks bladder/valve architecture is unambiguously free.
• § 315(b) — because no timely complaint can exist, no IPR window can open, and there is nothing for a defendant to petition on.

Pattern signals. None of the usual red flags appear: no serial petitioner, no PTAB appeal trail, no defensive aggregator (no Unified Patents, RPX, or similar in the chain — the ODP "Current Assignee" is the US Department of Navy), and no Federal Circuit activity. The patent's entire litigation footprint appears to be zero. It has functioned purely as technical literature — its only known downstream evidentiary role is as the category-"A" background reference in the EP1321054A3 search report for the Bauer/Nike inflatable-bladder hockey helmet.

Recommended next steps

• If you have received a demand letter or been named in a complaint citing US 4,035,846, treat it as a Rule 11 / § 285 problem. The patent expired 1994-07-19 (https://patents.google.com/patent/[US4035846A](/patent/US4035846A)). Quote that date and the "Expired - Lifetime" status back. There is no claim anyone can assert, so no Rule 12(b)(6) motion practice on patentability is even necessary — dismissal follows from the expiration date alone.
• Cite the absence of PTAB activity affirmatively. The USPTO PTAB E2E portal (https://ptacts.uspto.gov/ptacts/) and PTAB Decisions page (https://www.uspto.gov/patents/ptab/decisions) return nothing for this number; CourtListener (https://www.courtlistener.com/) shows no Federal Circuit appeal naming it. An empty PTAB docket on an expired, never-asserted Navy patent is the strongest possible signal that no live right is in play.
• Do not confuse this patent with the many other "'846" patents. If opposing counsel's briefs reference IPR papers involving an '846 patent (Immersion/Samsung haptics, the CM HK patent, the Wilus patent, or the BrainGuard/Revelyst line), those involve entirely different numbers. Demand the full number and the Google Patents / EPO family link before conceding anything.
• No PTAB milestones to track, because no trial exists. There is no institution deadline, no oral hearing, and no statutory 1-year FWD date to calendar. The correct calendar entry is a single date: the 1994-07-19 expiration.
• Caveat on completeness. My searches targeted the patent number, title, inventor, and likely petitioner/adversary names. I found no AIA proceeding, and the ODP block is the canonical list and shows none. I cannot, however, rule out a sub-2012 interference or a pre-1994 district court action that never generated an indexed opinion — if you need that historical sweep, pull the paper prosecution file and the Navy's assignment record via USPTO PatentCenter and the Assignment database.

I'll reconstruct the assignment record for US 4,035,846. Let me start with targeted searches of the USPTO assignment databases and cross-references.

Initial searches produced noise (fishing reel DE 4035846). Let me query the assignment databases and legal-events sources directly.

The searches confirm the fishing-reel "DE 4035846" is a persistent false positive. Let me verify the patent's front-page assignee data and probe the assignment database directly.

Inventors

Craig S. Jencks — sole named inventor. No co-inventors are listed anywhere on the face of US 4,035,846 or in the specification.

• Employer at filing: Consistent with U.S. Navy employment (civilian engineer or naval officer). The specification carries the standard Government-interest recital — "The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor" — which is the boilerplate used when an invention is made by a Government employee or under Government contract. The disclosed application (a helmet-mounted weapon-control line-of-sight system for VTAS, the Navy's Visual/Aircraft Target Acquisition System) is squarely a Navy aviation program. I cannot determine Jencks's specific duty station, command, or job title from the available record, and I will not guess.
• Unusual patterns: None detectable, and this is a coverage limitation rather than a clean bill of health. There is only one inventor and no assignment records to inspect, so the classic tell (all inventors departing the original assignee within 12 months of filing, preceding a portfolio fire-sale) cannot be tested. There is also no evidence for such a pattern. Note that a Government-employee invention is not the fact pattern where that tell is normally diagnostic.

Original assignee

U.S. Department of the Navy — listed as both Original Assignee and Current Assignee on the Google Patents record for US 4,035,846.

• Caveat on this data point: Google Patents applies its own disclaimer ("The listed assignees may be inaccurate. Google has not performed a legal analysis…"). The authoritative full text supplied for this patent recites the Government-interest statement but does not reproduce a [73] Assignee field. Google's assignee value for 1970s Navy patents is frequently derived from that Government-interest recital rather than from a literal front-page assignee entry. Treat "Department of the Navy" as well-supported but not independently confirmed against the printed face page in this session.
• Primary line of business: A U.S. federal military department. It does not "ship products" in the commercial sense; it develops and fields military systems, frequently through prime contractors.
• Product embodying the claims: Unclear. The claimed subject matter (an inflatable bladder + pressure-compensating valve stabilizing a helmet shell on the wearer) is a Navy aviation-development concept. Whether any production aviator helmet incorporated this specific bladder is not determinable from the patent or from the sources reached; no commercial embodiment exists because the rights are Government-held.
• Current status: Operating (a federal agency). It has not been acquired, dissolved, or placed in bankruptcy. The patent itself is Expired – Lifetime, with an anticipated expiration of 1994-07-19, recorded on the Google Patents legal-events timeline.

Assignment timeline

Plainly stated: I found no recorded post-issuance assignment for US 4,035,846, and I could not retrieve any assignment record (reel/frame, conveyance, assignor, assignee, or correspondent) for it. There is therefore no timeline to enumerate, and I will not construct reel/frame citations that do not exist.

Two independent reasons support the "no records" conclusion, with the limits of each stated honestly:

1. Database coverage window. The USPTO Patent Assignment Search / Assignments on the Web (AOTW) database — the source behind both https://assignmentcenter.uspto.gov/ and the legacy https://assignment.uspto.gov/patent/index.html — contains recorded assignments only from August 1980 forward (confirmed by USPTO's own Assignment Database materials: "This searchable database contains all recorded Patent Assignment information back to August 1980"). US 4,035,846 was filed 1976-08-17 and granted 1977-07-19 — its entire provenance predates the database's coverage. Any inventor-to-Government assignment instrument would have been recorded on microfilm in 1976–77 and is not queryable online by patent number. Pre-1980 documents must be ordered separately from the USPTO (fee-based), and I could not do so here.
2. No post-1980 activity. Google Patents' legal-events block for this patent shows only Filed (1976-08-17) → Granted/Published (1977-07-19) → Anticipated expiration (1994-07-19). There is no "Assignment" legal event. For a Government-owned patent this is expected: title stays with the agency, and there is nothing to record. (Legal-events data on 1970s patents is sparse, so I weight this as corroborating, not dispositive.)

Verification limits — stated so you can calibrate: my direct attempts to pull assignment-search results for the number returned only document/noise hits in this session, not the Assignment Center's result grid. My "no records" call therefore rests on (a) the database's post-August-1980 coverage, (b) the absence of any Google Patents assignment-type legal event, and (c) the independent no-litigation finding from the previous section. To close this out authoritatively, run the patent number at https://assignmentcenter.uspto.gov/ (Advanced Search → Patent Numbers) and request the pre-1980 microfilm reel from the USPTO Assignments Recordation Branch.

Because the record shows no assignment beyond original Government ownership, the same practical conclusion the prompt anticipates applies: the original assignee (the U.S. Government, via the Department of the Navy) has retained ownership throughout. Per the conditional instruction ("If the Assignment Center has no records… stop after this section"), there are no reel/frame entries to build on — but because the verdict taxonomy expressly provides for the "no records, or only the original assignment" case, I complete the remaining requested sections below at your specification.

Timeline diagram

timeline
    title Ownership of US 4035846
    1976 : Filed by Craig S Jencks
         : Government interest recited
    1977 : Patent granted
         : US Navy listed as assignee
    1980 : Online assignment records begin
    1994 : Patent term expires

NPE / troll-pattern signals

Every signal is assessed against the evidence actually in hand. Where the record is silent, I mark it not present (no evidence) and say so rather than implying an affirmative clean bill.

1. Shell-entity transfer — not present. No assignment to any "IP / Patents / Licensing / Holdings / Ventures" entity exists in the record. The only identified owner is a federal agency. No single-member LLC, no registered-agent address, no Delaware/Texas shell appears.
2. Known asserter in the chain — not present. The current/original assignee is the U.S. Department of the Navy, which does not appear on any public NPE list (Acacia, Marathon, IV, IPNav, Wi-LAN/Conversant, Vringo, Pendrell, Round Rock, etc.). No asserters surfaced via Unified Patents or RPX directories.
3. Repeat correspondent across the chain — not present / no data. No assignment records exist, so there is no correspondent of record to examine for recurrence. Absence of data, not an exculpatory finding.
4. Cascading transfers — not present. No chained LLC transfers (<24 months) exist; there are no post-issuance transfers at all.
5. Pre-litigation transfer — not present. The prior section of this analysis found no infringement litigation ever naming US 4,035,846, so there is no first-suit date to measure a 6-month transfer against. The patent expired 1994-07-19, foreclosing assertion after that date in any event.
6. Bankruptcy fire-sale — not present. The assignee is a federal department; no Chapter 7/11 proceeding, no Kodak/Nortel/Polaroid-style asset sale.
7. Privateering — not present. No transfer from an operating company to an asserting NPE; no SEC 10-K/8-K disclosure of such a transfer (the assignee files no SEC disclosures as a private-sector issuer).
8. Defensive aggregator (anti-NPE) — not present. The chain does not terminate at RPX, AST, LOT, Unified Patents, or OIN. This is a Government-owned patent outside the defensive-aggregation market entirely.

Verdict

Insufficient data (no records, or only the original assignment).

Justification: no recorded assignment is retrievable for US 4,035,846 — the patent's 1976 filing and 1977 grant predate the USPTO Assignment Center's August-1980 coverage window, and Google Patents' legal-events timeline shows no assignment event, only Filed (1976-08-17) → Granted (1977-07-19) → Expired (1994-07-19). The sole ownership entry is the original Government assignee, the U.S. Department of the Navy. Zero NPE/troll signals are present — no shell-entity transfer, no known asserter, no cascading transfers, no pre-litigation transfer, no fire-sale, no privateering — and this is corroborated by the earlier independent finding of no litigation involving this patent. I deliberately do not select "Defensive / non-asserting," because that verdict is reserved for chains terminating at a defensive aggregator (RPX/AST/LOT/Unified/OIN), which is not what a Navy-owned patent is; the taxonomy-faithful pick for a bare-original-assignment record is Insufficient data.

Verify at: https://assignmentcenter.uspto.gov/ (patent number search for 4035846) and the legacy portal https://assignment.uspto.gov/patent/index.html — and, to be conclusive about the 1976–77 provenance, order the pre-1980 microfilm record from the USPTO Assignments Recordation Branch.

One cross-reference note: the previously generated litigation section and this ownership analysis are consistent — both identify the U.S. Department of the Navy as original/current assignee and both turn on the 1994-07-19 expiration. I found no contradiction between them. The only item worth flagging is the shared evidentiary soft spot carried over from that section: the "Department of the Navy" assignee designation traces to Google Patents' derived field, which that page itself disclaims as legally unverified.

I'll search for the patent and its cited references to build an accurate anticipation analysis.

Prior-Art Anticipation Analysis — US 4,035,846

Note on the record control patent: The number searched was 4035846, which resolves, without correction, to US 4,035,846 A — "Inflatable pressure compensated helmet stabilization system," inventor Craig S. Jencks, assignee The United States of America as represented by the Secretary of the Navy, appl. no. US05/715,039, filed 1976‑08‑17, granted 1977‑07‑19 (Google Patents record, corroborated by the patent PDF at patentimages.storage.googleapis.com/72/c1/14/5a4f5245771e32/US4035846.pdf). Searches returning "similar" numbers (e.g., DE 4035846, etc.) were excluded, per the instruction. Nothing in this analysis contradicts the earlier litigation section.

---

1. The claim set being tested

The "pressure difference vs. ambient" limitation (Claim 1 last element; Claim 2 last element; Claim 3 (c); Claims 4–5) is the point of novelty and the analytical fulcrum below. Under 35 U.S.C. § 102, a reference anticipates only if it discloses every element of the claim in a single reference (MPEP 2131). An analysis that stops at "inflatable liner in a helmet" is therefore insufficient.

---

2. The five cited references (the examiner's Citations list, from the US 4,035,846 record)

Discrepancy flagged (no auto-correction applied): The OCR header of the US 3,806,950 patent PDF reads "United States Patent [19] Spencer-Foote [11] 3,806,950," whereas Google Patents and FreePatentsOnline both name the inventor as "Curran J." I report both literally and do not resolve them; it does not affect the technical analysis.

---

3. Reference-by-reference § 102 assessment

3.1 US 3,310,811 A — Iacono, "Helmet enclosure"

Description. A protective (military/atomic-fallout) helmet enclosure. It claims a shell with a visor housing, a pivotally mounted transparent visor, cooperative gas-tight sealing means between the visor's upper edge and the housing, and a continuous sealing strip around the brim/lower visor edge to which an impervious garment connects. The shell receives "air-supplying tubing and air source."

§ 102 mapping. Discloses a helmet shell (Claim 1(a)) and arguably a fluid source in a generic sense. It does not disclose: an inflatable member disposed within the shell; a chin strap pressing the head; a "first plurality of fasteners" releasably fastening an inflatable member; a suspension plus a second plurality of fasteners; or any pressure-compensating valve means keyed to ambient pressure.

Result: Anticipates no claim. It is environmental/background art (aviator-helmet shell + visor + air supply), not anticipating art for any of Claims 1–5.

---

3.2 US 3,600,714 A — Hop N Gator Inc., "Hydraulic helmet"

Description. An outer resiliently deformable shell, an inner compressible (sponge-rubber) liner, and an intermediate hydraulic cushioning assembly of a plurality of spaced expandable cells extending coextensively with the top, front, rear and sides, interconnected by constrictive passageways for restricted fluid flow; a fill valve admits hydraulic fluid. Cells are grouped into front/left-side/rear/right-side sets communicating with a central sump.

§ 102 mapping.

• Discloses a helmet shell and a fluid-containing member disposed within the shell (Claims 1(a)/2(a)/3(a) read loosely on this).
• Its cell geometry (radiating cells + transverse outer cells fed from a sump) is conceptually adjacent to the manifold‑plus‑ducts geometry of US 4,035,846.
• Missing: the inflatable member is a hydraulic cushion whose cells are bonded (glue/cement), not fastened by a "first plurality of fasteners"; there is no source of pressurized fluid under regulation; and there is no pressure-compensating valve means keyed to a preset member-vs-ambient pressure difference. The fill valve is a one-time fill port, not a regulator.

Result: Anticipates no claim. Best characterized as § 103 background art showing fluid-filled helmet liners.

---

3.3 US 3,761,959 A — F. Dunning, "Inflatable padding for football helmet or the like" — the closest cited reference

Description. An inflatable padding (a base sheet + pillow sheet heat-sealed, e.g., polyvinyl) mounted on the interior surface of a helmet. It has a top/crown member, front, rear and side members, interconnected by short fluid-passageway sections, with a valve means (a self-sealing needle valve) enabling selective, substantially simultaneous inflation of certain members. The base sheet attaches to the inner shell by "adhesives, mating tapes of Velcro, or mechanical fasteners." It is expressly claimed "in combination with a helmet, and means securing said padding to said helmet." Crown member is a single egg-shaped cell with radiating flexible conduit arms to the side/front/rear members.

§ 102 mapping (claim-by-claim):

• Claim 1: Discloses shell (a) and inflatable member + first plurality of fasteners/Velcro (c, d) and a pressurized-fluid introduction means (e, albeit a needle-fed manual valve rather than a regulated source). Missing (b) the chin strap secured at each end that the inflatable member opposes, and missing (f) the pressure-compensating valve means. → No anticipation.
• Claim 2: Missing the "suspension disposed adjacent said member" plus the second plurality of fasteners (c, e), and missing (f). → No anticipation.
• Claim 3: Discloses shell + inflatable member, but missing (c) the pressure-compensating means. → No anticipation.
• Claims 4–5: Depend on 3; fall with it.

Result: Anticipates no claim, but is the most material reference: it supplies most of the structural elements (inflatable member in a shell, plural inflatable members, interconnecting conduits, hook-and-pile fasteners, crown + side/front/rear coverage). Its combination with a pressure-regulating valve taught elsewhere would be a § 103 argument, not § 102.

---

3.4 US 3,806,950 A — Curran J., "Bandage shock absorbers for safety helmets"

Description. A wound-dressing (bandage) stored inside a fluid-impervious container fitted with a two-way valve to admit/remove fluid, shaped as a skull-cap fitting between the helmet shell and the wearer's head, releasably attached to the interior of the shell by "interlocking nylon filament hooked fabric" / "nylon filament loop fabric" (i.e., a Velcro-type first plurality of fasteners). A stated object is to form an impact-absorbing helmet liner of the container + dressing, conforming to the head and to the shell.

§ 102 mapping.

• Discloses shell, a fluid-containing member within the shell, and hook-and-pile fastening to the shell interior — reading on Claim 1(a),(c-approx.),(d) and Claim 2(a),(b),(d).
• Missing: the inflatable member opposed to chin-strap forces (1(b)); the suspension adjacent the member plus a second plurality of fasteners (2(c),(e)); a source of pressurized fluid in the regulated sense (its valve is a two‑way fluid port); and, critically, any pressure-compensating valve means tied to a preset member-vs-ambient pressure difference (1(f)/2(f)/3(c)).

Result: Anticipates no claim. § 103 background art.

---

3.5 GB 1,378,494 A — Secr Defence, "Protective head gear"

Description / data-status. This reference appears in the US 4,035,846 citation list with priority date 1971‑12‑08 and publication date 1974‑12‑27, applicant the UK Secretary of State for Defence. The Google Patents class mapping for the US 4,035,846 family places parallel fluid-cushioning headgear in A42B 3/12 / 3/121 / 3/122 ("Cushioning devices with at least one layer or pad containing a fluid / inflatable"). I could not retrieve the full text of GB 1,378,494 A, so I decline to characterize its disclosure element-by-element.

Result (stated at the confidence actually supported): On the record available, I have no basis to find that GB 1,378,494 A discloses the pressure-compensating valve means (the difference-driven regulator of Claims 1, 2, 3 and, through dependency, 4–5). It should therefore be treated as fluid-/inflatable-headgear background art (§ 103), not an anticipating reference (§ 102) — but this conclusion is provisional pending the full document, and I flag it as such rather than assert it as verified.

---

4. Consolidated conclusions

4.1 No cited reference anticipates any claim under § 102. Every one of Claims 1–5 requires the ambient-pressure-referenced pressure-compensating means (Claim 1 element (f); Claim 2 element (g); Claim 3 element (c); Claims 4–5 by dependency). None of the five cited references discloses a valve/sensor arrangement that maintains a constant pressure difference between the inflatable member and ambient pressure, and none discloses the altitude-deflation / altitude-inflation behavior described in the specification. Because § 102 requires all elements in a single reference, no anticipation lies. This is consistent with the fact that the examiner cited these five references and nonetheless allowed Claims 1–5.

4.2 Closest-to-anticipating elements (for § 103 purposes, not § 102):

4.3 Single-reference test applied to claims 4–5. Claim 4 adds a first valve receiving pressurized fluid plus a pressure-difference sensing means; Claim 5 adds a pressure-relief valve holding the difference below a second preset value. These are precisely the altitude-compensation hardware found in US 4,035,846 (valve 43, sensor 45, relief valve 47). No cited reference shows the sensor-plus-relief pairing referenced to ambient pressure, so Claims 4 and 5 are the least exposed to the cited art — reinforcing the no-anticipation conclusion.

4.4 What would be required to change this. Anticipation of any of Claims 1–3 would require a single pre‑1976 reference disclosing, in one document, (i) an inflatable member inside a helmet shell (and, for Claim 1, a chin strap; for Claim 2, a suspension plus a second fastener set) and (ii) a valve that regulates member pressure relative to ambient pressure. None of the five cited references supplies (ii).

---

5. Caveats and open items

• Sources. The US 4,035,846 record was confirmed on Google Patents and via the patent PDF; the cited references were read through Google Patents, FreePatentsOnline, uspto.report, and the patentimages.storage.googleapis.com originals. Google Patents mirrors the USPTO record; I did not separately pull the USPTO PatentCenter file wrapper for the examiner's exact rejections, so the reason each of the five references was cited (background vs. rejection) is inferred.
• GB 1,378,494 A full text was not obtained (search limit reached); its § 102 position is provisional and explicitly flagged, not asserted.
• "Cited By" / "Similar Documents" lists are NOT prior art. The 48/80 later "Cited By" documents (e.g., US 5,050,240; US 5,085,320; US 5,259,071) post-date US 4,035,846 and cannot be § 102 art against it; likewise the "Similar Documents" list (e.g., US 3,905,615 Inflatable body and head restraint) is a similarity ranking, not a citation, and should not be treated as a Reference Cited.
• No identifier was auto-corrected. Where the inventor name for US 3,806,950 as printed ("Spencer-Foote") differs from the database listing ("Curran J."), both are reported literally.
• This is an anticipation (novelty) analysis only. It does not opine on § 103 obviousness combinations, which would require a separate motivation-to-combine analysis.

I'll research the cited prior-art references to ground the obviousness analysis in their actual disclosures.

Good detail on two references. Let me research the remaining three cited references.

Let me get details on the remaining two references (GB 1,378,494 and Curran US 3,806,950).

Obviousness Analysis — US 4,035,846 (35 U.S.C. § 103)

Builds on: the Verified Summary and Litigation sections above (claim text, § 102(b)-qualifying dates, ownership, and termination fields are taken from there and not repeated). New in this section: the element-by-element prior-art mapping, the combination rationales, and the counter-arguments. A contradiction flag appears at § 7.

---

1. Governing standard

The application was filed 1976-08-17, so pre-AIA 35 U.S.C. § 103(a) governs, applied through the Graham v. John Deere factors (scope/content of the prior art; differences; PHOSITA level; secondary considerations), with KSR Int'l v. Teleflex supplying the "motivation to combine" and "predictable use" rationales. All five examiner-cited references published 1967–1974, i.e., more than one year before the filing date, so each is § 102(b) art usable as a § 103 reference (the § 102(a)/(b) tables in the Verified Summary are adopted here).

Hypothetical PHOSITA: a mechanical/aerospace engineer (B.S. + ~2–3 years) designing aircrew life-support and protective headgear, familiar with (i) inflatable helmet liners, (ii) hook-and-loop attachment, and (iii) aeronautical pneumatic hardware — cabin-pressure controllers, oxygen-mask regulators, and pressure suits, all of which were mature by 1976.

Claim construction note: claims 1, 2, 3, 4 and 5 use "means" language ("pressure compensating valve means," "pressure difference sensing means," "pressure relief valve means"). Under pre-AIA § 112 ¶ 6, these read on the disclosed structure (valve 43, sensor 45, relief valve 47) and equivalents, which materially broadens their exposure to prior-art equivalents.

---

2. What each cited reference actually discloses

Critical observation: None of the five references discloses the element that defines every independent claim — a valve that passes pressurized fluid according to the variation from a preset value of the difference between the member's pressure and ambient pressure (i.e., constant differential, altitude-compensating regulation). That element is the entire point of novelty, and the § 103 case therefore turns on whether the record supplies (or the examiner can take official notice of) a pressure-differential regulator reference.

---

3. Obviousness of claims 1 and 2 — inflatable member + fasteners + chin strap/suspension

3.1 Claim 1 (chin-strap embodiment)

Combination A: US 3,761,959 (Dunning) + US 3,600,714 (Hop N Gator) + [pressure-differential regulator reference]

Combination B: US 3,806,950 (Curran) + US 3,600,714 (Hop N Gator) + [regulator reference] — Curran supplies the inflatable fluid-filled container, the hook-and-loop "first plurality of fasteners," and the two-way valve; Hop N Gator supplies the chin strap and shell.

3.2 Claim 2 (suspension/liner embodiment)

Combination C: US 3,761,959 (Dunning) + US 3,806,950 (Curran) + [regulator reference]

Curran is unusually strong here because it discloses both fastener pluralities and the liner relationship:

• First plurality (member→shell): nylon hooked/looped fabric tape, or snap fasteners.
• Second plurality (suspension→shell): Curran's container "releasably fastened … by means of male and female snap fasteners … to said suspension harness assembly," with the removable suspension harness of FIGS. 8–9; the shell-mounted suspension anchors complete the shell-side attachment.
• "Suspension disposed adjacent to said member": Curran's container is shaped to constitute the helmet liner occupying the shell-to-head space.
• Dunning adds multi-cell inflatable geometry and Velcro attachment if Curran is deemed insufficient.

3.3 Motivation to combine (KSR rationales)

1. Same field of endeavor / same problem. Dunning, Curran and Hop N Gator are all "inflatable or fluid-filled structure between a rigid helmet shell and the wearer's head for fit, cushioning and shell-to-head coupling." Combining them involves no change in principle of operation.
2. Predictable use of known elements. Placing a known inflatable liner inside a known shell and holding it with known hook-and-loop tape is the established function of each element — the classic KSR "predictable use" rationale.
3. Prior-art design incentive. Dunning expressly seeks a "snug custom-like fit"; Curran expressly seeks an "adjustable" liner. Stabilization against chin-strap loading is the natural, anticipated result of tightening an inflatable liner — no new discovery required.

---

4. Obviousness of claim 3 — the crux, and the strongest § 103 attack

Claim 3 is the broadest claim: shell + inflatable member + "pressure compensating means … for maintaining a constant pressure difference between the pressure within said member and the ambient pressure."

The applicant's own specification supplies the admissions that make this claim the most vulnerable:

• "[S]uch padding is generally designed to maintain a constant pressure within the padding. If such padding is used by an aircrewman, the volume of the padding, as the cabin ambient pressure varies with altitude, will also vary."
• The patent frames the fix purely as a change of controlled variable, from absolute bladder pressure to bladder-to-ambient difference: "the pressure within bladder 11 must vary with the ambient pressure."

Combined with any known pressure-differential controller (aircraft cabin-pressure controller, oxygen-regulator, anti-G suit valve), claim 3 becomes a textbook KSR case: the improvement is "the predictable use of prior art elements according to their established functions," and designing an inflatable liner for the known aircrew altitude environment, where the patent itself admits constant-pressure liners misbehaved, supplies an articulated reason to make the substitution. The same "known problem" logic supports analogous-art treatment of the regulator art (reasonably pertinent to the altitude-compensation problem).

Important caveat: the pressure-differential regulator is not among the five references of record. A § 103 rejection of claim 3 therefore must be augmented with a regulator reference or with official notice; see § 6.

---

5. Obviousness of dependent claims 4 and 5

• Claim 4 (first valve + pressure-difference sensor operating it at a first preset value) describes a conventional closed-loop pneumatic control: sensor → valve → controlled volume. Any pressure-differential regulator reference that discloses both a differential sensor and a supply valve also supplies claim 4's elements, so claim 4 stands or falls with the same regulator reference used for claim 3.
• Claim 5 (relief valve holding the difference below a second preset value) is a set-point/hysteresis arrangement routinely paired with a supply regulator (and expressly disclosed in Curran's two-way valve 62, which both admits and releases fluid, and in the patent's own admission that "valve 43 … could be configured to both admit and release … so that pressure relief valve 47 could be dispensed with"). That admission characterizes valve 43/relief valve 47 as interchangeable equivalents — damaging to claim 5 under KSR and, separately, under the § 112 ¶ 6 equivalents doctrine flagged in § 1.

---

6. Why the § 103 case is not complete on the cited art alone

Stated plainly: on the five references of record the claims are not obvious and, a fortiori, not anticipated. A reference-by-reference check shows every independent claim is missing the same limitation:

No single reference (anticipation) and no combination of the five (obviousness) discloses the differential-pressure control function. A § 103 rejection would require the examiner to add a pressure-differential regulator reference (aerospace pneumatics/cabin pressure control) and to explain why it is analogous art. Context supporting that gap being real: a helmet air-cushion with an air pressure regulator surfaces only in US 5,050,240 (Kaiser Aerospace, 1991) — sixteen years after this filing — and a self-contained pump in US 5,083,320 (not prior art here). That later date cuts both ways: it is evidence of industry delay (a nonobviousness/Graham secondary-consideration argument) and evidence that the field eventually arrived at the very combination, predictably.

---

7. Counter-arguments, weaknesses and flags

Counter-arguments favouring nonobviousness (which I must present, as this is a paper analysis of an expired patent):

1. No TSM or analogous-art bridge in the record. The five cited references are all helmet/liner art; the examiner cited no regulator art. An attorney could argue the helmet-suspension field of endeavor did not, as of 1976, look to cabin-pressurization pneumatics, and that the claimed regulator requires a bleed-air source and system integration foreign to the cited helmet art.
2. Failure of others / long-felt need. The background describes existing inflatable padding as unsatisfactory ("there is still a tendency for the helmet to shift"), and VTAS created a hard requirement for shell-to-head rigidity. The 14–16-year lag to a regulated helmet air cushion (1990–1991) is a classic secondary-consideration fact pattern.
3. Claim 4's "first preset value" and claim 5's "second preset value" are specific numeric set-points that, if read as requiring distinct, separately-set thresholds, may not be squarely met by a generic single-setpoint regulator.

Flags / uncertainties (consistent with, and additional to, the earlier sections):

• Flag 1 — GB 1,378,494 content not verifiable. Only its bibliographic record (title Protective head gear, Secr Defence, priority 1971-12-08, pub. 1974-12-27) was retrievable; the specification/claims text could not be fetched. I do not attribute any disclosure to it. If it discloses a suspension plus inflatable cushion (plausible given the title and assignee, but unverified), it would strengthen the claim-2 combination; if it discloses pressure regulation, it could be the missing regulator reference. Its actual content is the single most consequential unknown in this analysis.
• Flag 2 — post-AIA vs pre-AIA. The analysis applies pre-AIA § 103 because filing predates the AIA; do not import AIA § 102/103 definitions.
• Flag 3 — contradiction with the earlier OCR/authoritative-value discrepancy. The Verified Summary (§ Discrepancies, item 1) flags the OCR "1 pound per square inch" vs. authoritative "1/4 pound … 1/2 pound per square inch." That contradiction is not resolved by this section; it does not affect the § 103 outcome, because the claimed limitations are pressure-difference maintenance, not any particular numeric value.
• Flag 4 — legal effect is moot in practice. Per the earlier sections, the patent expired 1994-07-19 and was government-owned; no litigation was found. Any § 103 conclusion here is therefore retrospective/educational rather than a live invalidity exposure.
• Flag 5 — "Cited By" counts. As flagged earlier, the Google Patents page displays two different "Cited By" counts (48 and 80); I treat both as display artifacts and rely on individual reference entries only.

---

8. Bottom line

• On the five references of record alone: claims 1–5 are not obvious — the pressure-differential compensating element is absent from every reference individually and from any combination of them.
• With one added pressure-differential-regulator reference (analogous aeronautical pneumatics art): claim 3 is the most likely to fall — the applicant's own specification concedes that constant-pressure inflatable padding for aircrew was known and identifies the altitude-induced volume change as the problem to be solved. Claims 4 and 5 follow claim 3, especially given the specification's admission that the relief valve is dispensable/equivalent (Curran's two-way valve 62 reinforcing this).
• Claims 1 and 2 would require a three-reference combination (e.g., Dunning + Hop N Gator + regulator for claim 1; Dunning + Curran + regulator for claim 2), with the fasteners and chin-strap/suspension elements well supplied by US 3,761,959, US 3,600,714 and US 3,806,950, and with KSR "predictable use / known problem" rationales providing the motivation.
• Decisive for any real challenge: finding the actual content of GB 1,378,494, and locating a 1970s-era pressure-differential regulator reference reasonably pertinent to altitude compensation. Without at least one of those, the obviousness case cannot be closed on this record.

Primary sources: US 3,761,959 · US 3,600,714 · US 3,806,950 · US 3,310,811 · GB 1,378,494 · US 4,035,846.