US 3668704

I'll check for any current USPTO records or litigation activity on this specific number.

US Patent 3,668,704 — Summary

Source of record: Google Patents full text (https://patents.google.com/patent/[US3668704](/patent/US3668704)/en), fetched 2026‑09‑24. FreePatentsOnline mirror (https://www.freepatentsonline.com/3668704.html) corroborates the claim text.

Bibliographic data

Note on priority: the record lists the priority date as 1970‑07‑13, the same as the filing date. Because the specification states this is a CIP of Ser. No. 12,805 (filed 1970‑02‑19), earlier subject matter may be entitled to the 1970‑02‑19 date, but the database's listed priority date is 1970‑07‑13. I flag this rather than resolve it.

Abstract (as published)

"An inflatable member dimensioned to be mounted to the inside curvature of a rigid shell, and to be preferably inserted within a slightly oversized foamed elastomeric envelope which is bonded to the inside curvature of said shell. Air fill means are provided so that the user can inflate the member by introducing air to a plurality of communicating compartments within the member, and thereby both size the head gear assembly and cushion the head of the user against shocks."

Plain-language overview of the independent claims

Claim 1 — Inflatable cushioning/sizing means (the liner itself).
A T‑shaped inflatable bladder for mounting inside a hard head shell. Elements:

• Two sidewalls conforming to the T‑shape; one sidewall is substantially thicker than the other, the thicker one being a substantially non‑distendable support wall (it holds shape rather than bulging).
• Anchoring tabs along the peripheral margin of the arms, each with fastening means for mounting tabs directly to the shell.
• Sidewalls sealed along their peripheral edges.
• Horizontal arm long enough to wrap around the opposite temporal portions of the head to about the medial line of the forehead; a vertical arm.
• An elongated air‑fill tube communicating between the sealed sidewalls, long enough for the wearer to reach it with their mouth while the liner is in the worn shell.
• Multiple communicating compartments created by discontinuous seal lines, so air passes between compartments (uniform distension with less air than an undivided bladder).

Claim 2 — Protective headgear assembly (shell + liner system).
A substantially rigid head shell combined with the cushioning/sizing assembly. Elements:

• Member with two sidewalls (head‑side and shell‑side), sealed along peripheral edges to form an arm long enough to extend around the opposite temporal portions of the head to about the medial line of the forehead.
• Elongated air‑fill tube between the sealed sidewalls, long enough to reach the wearer's mouth when mounted in the shell.
• A removable closure for the tube end.
• A plurality of communicating compartments formed by discontinuous seal lines providing inter‑compartment air passageways.
• Cushion means along both opposite sidewalls, serving both to cushion the head and to mount the inflatable member to the inside of the shell.

Dependent claims (brief)

• Cl. 3 (dep. 2): cushion means is a slightly oversized envelope with at least a foamed elastomeric covering on the head side, plus access means.
• Cl. 5 (dep. 2): T‑shape with horizontal arm around temporal regions and vertical arm over the medial crown line to about the forehead.
• Cl. 6 (dep. 2): unbranched single‑arm version.
• Cl. 7 (dep. 2): H‑shape — two vertical arms (forehead and back) flanking an intermediate horizontal arm on the medial line; air‑fill tube at an end compartment of a vertical arm.
• Cl. 8 (dep. 1): supporting straps joined to the vertical arm with double‑layer anchoring tabs, sized to hold the vertical arm spaced from the shell's inside curvature (a suspension mount).
• Cl. 9 (dep. 2): assembly mounted in a shell with a continuous curvilinear bottom edge; cushion means held to the shell curvature by a plurality of bonding points.
• Remaining claims (4, 10–16) are directed to the open‑top envelope, ventilating areas above the envelope arm, the ear‑clearance edge profile, and material selections (foamed rubber envelope, vinyl thermoplastic inflatable member, friction‑fitted removable cap on the fill tube), plus T‑ and H‑shape envelope variants.

Drafting anomalies to note (reproduced literally, not corrected): several dependent claims contain defective cross‑references in the granted text — e.g., claim 4 recites "as in claim 4" (self‑referential), claim 10 recites "as in claim 11," and claim 11 recites "as in claim 12." These are internal inconsistencies in the printed patent. The only genuinely independent claims are 1 and 2. Also, the printed text is OCR‑degraded (e.g., "wihtin," "saidcushion," "The inflatable T-shaped like"), and claim 1 includes a comma splice ("…and a plurality of anchoring tabs being disposed…") suggesting a truncated/merged claim as printed.

Prior art cited on the face of the patent (11 references)

US 1,833,708 (Ford, "Pneumatic headgear"); US 2,033,802 (Abram); US 2,575,764 (Morner); US 2,759,186 (Dye — Cornell Aeronautical Lab, "Pneumatic suspension for safety helmet"); US 2,803,015 (Milone, "Inflatable hat"); US 2,983,923 (Frieder); US 3,039,109 (Electric Storage Battery Co., "Lining for safety helmets"); US 3,168,382 (Sunbeam Corp.); US 3,221,340 (Park Plastics); US 3,440,660 (Krinke, "Storable protective headgear"); US 3,551,911 (George Frost Co.). The specification additionally discusses US 3,248,738, US 3,186,004, US 3,462,763, and US 3,254,883.

Forward citations are extensive (100+), notably US 3,761,959 (Dunning, inflatable padding for football helmets), US 5,175,889 (Riddell, inflatable liner), US 6,530,092 (Southern Impact Research Center, fitting/comfort system with inflatable liner), and various Xenith, Intellectual Property Holdings, and Loubert S. Suddaby helmet patents.

Litigation / docket status — explicit uncertainty

I searched for CAFC 2026 docket activity and USPTO litigation records tied to US 3,668,704 and found none. Given the patent's 1989 expiration (17 years from the 1972 issue date), the absence of any live litigation is expected and consistent. I cannot affirm from an authoritative docket source that there are zero historical suits; I simply found no records. No CAFC proceedings involving this patent number were located.

Number‑collision caution (interpreted literally, per your instruction): search results also return unrelated documents bearing the digits 3668704 in other jurisdictions and formats — e.g., JP 3668704 B2 (Honda Lock / Honda Motor, "communication mode change method in in‑vehicle remote control," registered 2005) and an EP publication 3668704 (Krones AG, blow‑molding machine). These are distinct identifiers and must not be conflated with US 3,668,704.

Uncertainty summary

• Inventors, filing date, issue date, title, abstract, and claim text are high‑confidence (taken from the full granted text).
• Assignee is high‑confidence: named individuals only; I saw no assignment to a company in the record provided.
• Priority date is medium‑confidence: database says 1970‑07‑13, but the CIP parent (Ser. No. 12,805, filed 1970‑02‑19) may carry earlier priority for some subject matter; the record does not resolve this.
• Litigation/docket status is negative finding only — no CAFC 2026 activity identified for this number.

I'll research litigation involving US patent 3668704 across litigation-tracking sources.

Let me search additional litigation-specific sources.

Let me try a few more targeted litigation sources and confirm the patent's legal status.

Bottom line

I found no record of any litigation involving U.S. Patent No. 3,668,704. Based on the searches above, no district court action, ITC investigation, or CAFC appeal asserting or challenging this particular patent is publicly indexed. I cannot give you a plaintiff/defendant/jurisdiction/case-number table because there is nothing to populate it with.

What I verified about the patent (grounding the "no litigation" conclusion)

The authoritative full text confirms the following, each of which makes litigation unlikely and, if it existed, would have occurred in a narrow historical window:

Two facts drive the conclusion:

1. The patent expired June 13, 1989 — its full 17-year term. Any infringement action would have had to be filed on or before that date (and would have been subject to the 6-year § 286 damages lookback). Enforcement today is legally impossible.
2. It was never assigned to an operating company. Both the original and listed current assignees are the two individual inventors. There is no corporate patent-holding entity (no Riddell, no Schutt, no Gentex, etc.) that would appear as a plaintiff in a later infringement suit.

False positives I filtered out (do not confuse these with US 3,668,704)

My searches returned several documents containing the digit string "3668704" that are unrelated to this patent:

• JP 3668704 B2 — a Japanese patent (特許第3668704号) to Honda Lock / Honda Motor, directed to a vehicle remote-control communication mode (Int. Cl. E05B 49/00). Different jurisdiction, different subject matter.
• EP 3668704 — a European patent validation (187858105) listed in a Belgian patent register (Krones AG/Laempe Mössner Sinto context). Different jurisdiction.
• 2020 WL 3668704 — a Westlaw citation for Basile v. Prometheus Global Media (Ill. App. 2020), cited in an anti-SLAPP appeal. Not a patent case.
• The Daignean Technologies v. Ericsson/Nokia/T-Mobile and Riddell v. Schutt / Kranos IP helmet cases surfaced for keyword reasons only; none of them asserts the '704 patent.

Caveats on methodology (stated explicitly, per your instruction)

• I could not run a direct, docket-level query against PACER or the Unified Patents litigation portal in this session (those are gated/search-restricted interfaces). My conclusion rests on publicly indexed web sources plus the authoritative patent record.
• This means my "no litigation" finding is a negative result from available public sources, not a certified PACER full-docket clearance. If you need a defensible legal conclusion, the confirmatory step would be a name/patent-number search in Lex Machina, Docket Navigator, or PACER for "3,668,704" and for the inventors Conroy/Hauger as plaintiffs, covering 1970–1989. A pre-1989 case may not be in modern electronic databases at all, since PACER coverage of older district court dockets is incomplete.
• Given the patent's 1989 expiration and individual (non-corporate) ownership, even a full docket search is unlikely to change the answer.

Statement of the result: No litigation is known involving US Patent No. 3,668,704.

PTAB Proceedings — US 3,668,704 ("Protective Headgear," Conroy & Hauger)

Proceedings overview

Total AIA trial proceedings on file: 0 — zero IPRs, zero PGRs, zero CBMs. The USPTO Open Data Portal returns no AIA trial proceedings for US 3,668,704 as of the most recent ingest, and independent web searching (PTAB decisions, PTAB E2E / PTACTS, CourtListener-adjacent sources, Unified Patents-type challenger activity) surfaced no petition, institution decision, Final Written Decision, or appeal naming this patent. Because there is nothing to break down by status (no active proceedings, no claims invalidated, no claims sustained, no settlements, no institution denials), there is no claim-level PTAB outcome to report and no "hardened patent" / "cancelled claims" narrative applies here at all. The bottom-line defensive posture is different in kind from a typical troll-target patent: this patent is long expired (anticipated expiration 1989-06-13), so the absence of PTAB activity reflects lack of economic incentive rather than a patent owner who successfully fended off challengers. Any demand letter asserting live infringement of the '704 patent is facially defective — the patent has been in the public domain since 1989, and even the six-year look-back for past damages (35 U.S.C. § 286) closed in the 1990s.

Important caveat on sourcing: this section is built from the canonical "PTAB proceedings on file" block in the prompt (USPTO ODP) plus public web searching. I did not find any proceeding I could cite, and I am explicitly not supplying proceeding numbers, panel compositions, or claim-level dispositions, because fabricating them would be worse than reporting the null result. If your diligence requires a belt-and-suspenders check independent of ODP ingest lag, the two places to look are PTAB E2E / PTACTS (https://ptacts.uspto.gov/) searched by patent number, and the PTAB Decisions page (https://www.uspto.gov/patents/ptab/decisions) filtered by the '704 patent number.

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Per-proceeding detail

None. There are no proceedings to detail.

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Strategic summary

Claim status. All 16 claims of US 3,668,704 remain as issued: claims 1–8 (inflatable T-shaped cushioning/sizing member, anchoring tabs, suspension straps), claims 2–3, 5–7, 13, 14 (unbranched, T-shaped, and H-shaped variants with an oversized foamed elastomeric envelope), and claims 9–12, 15, 16 (envelope-plus-shell assemblies, ventilating areas, foamed-rubber/vinyl/friction-cap species claims). No claim is canceled; no claim has been tested in an AIA trial. The claims' substantive validity posture has never been adjudicated by the Board. Two drafting artifacts worth flagging if you ever have to read this patent closely: claim 4 contains a self-referential dependency ("as in claim 4"), and claim 10 depends from "claim 11" while claim 11 depends from "claim 12" — a circular dependency chain (10 → 11 → 12 → 4). Those indefiniteness/§ 112 issues are exactly the kind of thing an IPR petitioner would ordinarily lead with, and their existence reinforces that no one ever considered this patent worth the filing fee.

Estoppel landscape. Because no AIA trial was ever instituted, § 315(e)(2) estoppel does not exist against anyone — there is no petitioner and no privy carrying estoppel from an IPR, PGR, or CBM. That means IPR is not foreclosed as a vehicle. It is foreclosed in practice for a much simpler reason: 35 U.S.C. §§ 311(c) and 321(c) require that the petition be filed within one year of service of a complaint alleging infringement, and IPR/PGR are only available for patents subject to challenge — an expired patent presents no live infringement theory, so there is no complaint to trigger the window and no controversy to justify the petition. Practically, all prior art remains "available" to a defendant in the limited sense that no estoppel blocks it, but the patent itself is unusable as a litigation weapon. The strongest available art, if you need it for a defensive invalidity contention or an IPR-vs-patent dispute over a family member, is the examiner-cited set on the face of the patent: US 1,833,708 (Ford, "Pneumatic headgear," 1931-11-24); US 2,033,802 (Eva, bathing cap, 1936-03-10); US 2,575,764 (Morner, air-filled upholstery, 1951-11-20); US 2,759,186 (Cornell Aeronautical Lab, pneumatic suspension for safety helmet, 1956-08-21); US 2,803,015 (Milone, inflatable hat, 1957-08-20); US 2,983,923 (Frieder, rigging for protective helmet, 1961-05-16); US 3,039,109 (Electric Storage Battery, lining for safety helmets, 1962-06-19); US 3,221,340 (Park Plastics, harness with rigid hat, 1965-12-07); US 3,440,660 (Krinke, storable protective headgear, 1969-04-29); US 3,551,911 (George Frost Co., 1971-01-05). Note the prosecution also relied on art the specification itself discusses (US 3,186,004, US 3,254,883, US 3,462,763, US 3,248,738).

Pattern signals. None of the classic patterns are present. No repeat petitioner (zero petitioners), no patent-owner appeal campaign to the Federal Circuit (there is no FWD to appeal — an appeal under § 319 requires a written decision, and a dissatisfied party cannot appeal an institution denial to the CAFC), no defensive aggregator such as Unified Patents in the chain. The forward-citation trail does show the patent was influential on later helmet-liner art — 76 "cited by" entries in the ODP data, growing to 101 in the broader Google Patents record, including Riddell's inflatable liners (US 5,175,889; US 5,263,203), Maxpro's gas-fitted helmet (US 5,014,365), Athletic Helmet's self-contained air pump (US 5,083,320), Southern Impact Research Center's fitting systems (US 6,178,560; US 6,530,092), Gentex's individually fitted helmet (US 4,239,106), and the Xenith family (US 7,774,866 et seq.). That citation depth is the reason this patent is still cited in modern prosecution — but citation as prior art is not assertion, and none of those citers ever filed against it at the Board.

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Recommended next steps

1. If you are a defendant and the demand letter is live: the defense is not an IPR — it is expiration. US 3,668,704 issued 1972-06-13 and its anticipated expiration was 1989-06-13 (17-year term, pre-URAA patent). The patent bears status "Expired – Lifetime" in the ODP record. Any damages theory is time-barred by 35 U.S.C. § 286, and any injunction theory is moot. There is no FWD to link — because none exists — so you should not represent to a court or an adversary that claims were "cancelled." Instead, quote the structured status field and the expiration date, and supplement with a USPTO PatentCenter/PAIR print showing the "Expired – Lifetime" status and the fee/expiration history.

2. If you need an affirmative invalidity record anyway (e.g., a client insists, or you are clearing a product where a counterpart foreign family member matters): the only mechanism left is ex parte reexamination under 35 U.S.C. § 302, which has no one-year bar and no "live infringement controversy" requirement. Note that § 315(e)(2) estoppel would attach to the requester only for ex parte reexam grounds actually presented in a later IPR — and no later IPR is possible here. I found no reexamination certificate or record in the materials I reviewed, but the ODP block only speaks to AIA trials; a separate PAIR/PatentCenter reexamination-family check is the one verification step I could not complete and would recommend before you state "no post-issuance USPTO proceedings of any kind" in writing.

3. Procedural milestone tracking: inapplicable — there are no active proceedings, so there is no institution deadline, no oral hearing, and no one-year § 316(a)(11) FWD clock running. Nothing on this patent's PTAB docket will ever mature.

4. The one thing not to do: do not build a defense around PTAB claim cancelation. The value of this patent to a modern licensor is purely as prior art against other people's inflatable helmet-liner claims (and there it is genuinely valuable given the 100+ forward citations). If a counterparty is asserting a later patent and citing the '704 as prior art against you, that is a prosecution-history estoppel and obviousness argument about their claims — not a PTAB-proceedings point about this one.

I'll start by checking for any recorded assignment activity and cross-referencing the named parties.

Let me check for litigation history, any corporate affiliation of the inventors, and confirm the assignment record status.

Ownership & Assignment Analysis — US 3668704 "Protective Headgear"

Method note / limitation. I ran this from the authoritative patent text (Google Patents, https://patents.google.com/patent/US3668704/en) plus indexed searches for assignment, litigation, and assignee records. The USPTO Assignment Center is not queryable from my tools, so the statement below rests on (a) the absence of any assignment entry in the patent's own legal-events history and (b) the absence of any assignee field on the face of the patent. Independently verify at https://assignmentcenter.uspto.gov/ (search patent number 3668704) and https://assignment.uspto.gov/patent/index.html. Coverage caveat: the USPTO assignment database only reaches back to August 1980; the events that matter here (filing 1970, issuance 1972) predate coverage, so an unrecorded pre-1980 employer assignment could exist off-register.

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Inventors

Both inventors are listed at residential addresses, and the patent face carries no assignee (§73) entry. Google Patents accordingly renders both the "Original Assignee" and "Current Assignee" fields as JOHN H HAUGER and ROBERT E CONROY — i.e., the inventors themselves, as individual co-owners. This is the classic independent-inventor filing signature (self-owned, unassigned), not a corporate filing.

Unusual-pattern check:

• No employer-assignment at filing → the usual "inventors assign to Acme Corp, then leave" fire-sale precursor cannot apply here.
• No inventor-departure event is observable, because there was never a corporate assignee to depart from.
• The case is a continuation-in-part of Ser. No. 12,805, filed 1970-02-19, now abandoned, by the same two applicants. That parent never issued, so the family is a single US patent with no foreign counterparts (Google Patents family ID 21991610; "Family Applications (1)"; "Country Status (1) — US"). A one-patent, two-individual portfolio is economically consistent with an independent inventor pair, and is the opposite of a portfolio assembled for assertion.

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Original assignee

There is no corporate original assignee. The patent issued to the two inventors individually — John H. Hauger and Robert E. Conroy — with no §73 assignee named. Google Patents' "Original Assignee" and "Current Assignee" fields both name the inventors, and the legal-events history contains only:

• 1970-07-13 — Application filed by JOHN H HAUGER, ROBERT E CONROY
• 1972-06-13 — Application granted
• 1972-06-13 — Publication of US3668704A
• 1989-06-13 — Anticipated expiration
• Status: Expired – Lifetime

Product embodying the claims: No commercial entity is named anywhere in the record, so there is no assignee-side product to trace. The patent describes a hockey-style helmet embodiment (Figs. 6–8) with a rigid shell and ventilating holes, but no manufacturer is identified. Primary line of business: not applicable — the owner of record is a pair of natural persons. Current status: the inventors are the only owners ever of record, and the patent expired for full term on 1989-06-13, meaning any residual rights passed into the public domain 37 years ago. (US patents filed in 1970 were not subject to post-1980 maintenance-fee windows, so no fee-lapse event applies.)

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Assignment timeline

No assignment records exist for US 3668704 in the sources checked, and the patent's own legal-events record shows no conveyance of any kind after issuance. There is no reel/frame to cite, no assignor/assignee pair, and no correspondent of record — because no document was ever recorded against this patent in the indexed history.

The only ownership-relevant events are the natural lifecycle entries above (1970 filing → 1972 grant → 1989 expiry). The chain is: two individual inventors → (no transfer) → public domain.

Per the stated house rule, the assignment analysis stops here: with no recorded post-issuance assignments, the operative finding is that the original owners — the inventors — retained title for the life of the patent. The remaining sections are supplied only to close out the requested schema, and they contain no assignment-derived findings.

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Timeline diagram

timeline
    title Ownership of US 3668704
    1970 : CIP filed by Conroy and Hauger
         : Parent case Serial 12805 abandoned
    1972 : Patent US 3668704 issued
         : Inventors named as sole owners
         : No corporate assignee on record
    1989 : Patent expired after full term
    2026 : No assignment records found

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NPE / troll-pattern signals

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Verdict

Insufficient data — the schema's label for a patent with no recorded assignments beyond original ownership. On the merits, this is not a null finding: the absence of any transfer is itself exculpatory. The patent issued 1972-06-13 to Robert E. Conroy and John H. Hauger as individuals (no §73 corporate assignee), the legal-events record shows only filing, grant, and anticipated expiration on 1989-06-13, and no assignment document, reel/frame, or correspondent of record exists to analyze. There is therefore no shell entity, no known asserter, no cascading LLC chain, and no pre-litigation transfer — no NPE pattern can be constructed from this record, and the patent has been in the public domain since 1989, so it cannot be asserted by anyone.

Verify at: https://assignmentcenter.uspto.gov/ (patent number search: 3668704) · https://assignment.uspto.gov/patent/index.html · legal events: https://patents.google.com/patent/US3668704/en

I'll verify the patent record and pull details on each cited reference.

Now let me research the remaining cited references.

Prior-Art Analysis — US 3,668,704 ("Protective Headgear")

0. Record confirmation (USPTO)

Searched and confirmed: the number 3668704 resolves to US 3,668,704 A, "Protective Headgear," Robert E. Conroy & John H. Hauger, App. No. 54,513, filed & priority 1970-07-13, issued 1972-06-13, 16 claims, expired 1989-06-13. The granted text I am analyzing is the USPTO text as mirrored at Google Patents and FreePatentsOnline. No other "3668704" document was used (see §5 number-collision caution). This builds on the two earlier sections; I do not repeat the claim summary here.

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1. The 11 references cited on the face of the patent

All were cited by the examiner (Examiner James R. Boler). Statutory note up front: every one of these predates the 1970-07-13 filing for § 102(a)/(b) purposes except US 3,551,911, which issued 1971-01-05 — after the '704 filing — and therefore can only be § 102(e) art as of its own filing date (1969-02-04). That asymmetry matters and is easy to miss.

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2. Reference-by-reference § 102 analysis

Headline finding — state it plainly: No single cited reference anticipates independent claim 1 or independent claim 2 under § 102. Anticipation requires every limitation in one reference; each of the four or five closest references misses at least one express claim element, principally the elongated mouth-reachable air-fill tube, the asymmetric non-distendable support wall, and the T/H-shaped single peripherally-sealed member with anchoring tabs. The cited art is best characterized as § 103 obviousness art, grouped below. What follows is where each reference lands against specific claims.

1. US 1,833,708 (Ford) — the § 103 anchor for claim 1's asymmetric wall

Google Patents text confirms Ford discloses a football helmet whose bladder has "the inner wall … of considerable thickness so that the expansion of the bladder … will [be] against … the outer casing", and the claim language literally recites "the inner walls of greater thickness than the outer walls, for the purpose of causing the expansion of the bag toward and against the outer casing."

• Reads on: claim 1's "one of said sidewalls being substantially thicker than the other … a substantially non-distendable support wall"; claim 9's shell-with-curvature context.
• Missing for § 102: no T-shape, no anchoring tabs/fastening means, no elongated mouth tube (Ford uses a bladder valve 7 on the helmet side), no discontinuous-seal compartments. Does not anticipate claim 1. Strong § 102(a)/(b)+§ 103 art against the wall-asymmetry element.
• Source: https://patents.google.com/patent/[US1833708A](/patent/US1833708A)/en

2. US 2,033,802 (Abram, "Bathing cap")

Elastomeric/flexible head covering. No inflatable liner, no shell, no compartments. Anticipates nothing. Confidence note: I verified the identity/dates but not the interior disclosure; the title and field indicate it is general elastomeric-headwear art only. § 103 relevance is marginal (flexible head-covering materials).

3. US 2,575,764 (Mörner) — compartment-fabrication art

Air-filled upholstery and its method of manufacture — sealed pockets in coated fabric. Reads on the general concept of a sealed, multi-cell air cushion made by seam lines, i.e. claim 1/2's "discontinuous seal lines … communicating passageways" concept. Anticipates nothing (different field, no helmet, no shell, no tube). § 103 art for the compartment/seal-manufacture element. Confidence: medium — relied on title/known subject matter, not verified text.

4. US 2,759,186 (Dye / Cornell Aeronautical Lab) — the closest reference, and the primary § 103 reference

This is the most material citation, and the text bears that out. Dye discloses:

• pneumatic pillows in a rigid plastic safety-helmet shell, a lower row encircling the head at brow level and an upper row on the crown;
• pillows of polyvinyl heat-sealed sheet — "two strips … joined together or heat sealed along their upper and lower margins … and also joined together or heat sealed in a transverse direction at intervals";
• decisively: "Each area or narrow band of transverse sealing … is interrupted at about its center … so as to leave a narrow portion of the plys unbonded and thereby provide a narrow passage … the interiors of all cells are in communication with one another through the interconnecting restricted passages."
• a filling stem 35 with an internal check valve; adjustable inflation/deflation.

Mapping to claim 2: this reads directly on "a plurality of communicating compartments within the arm formed by discontinuous seal lines to provide communicating air passageways between the compartments" and on "cushion means … for mounting the inflatable member to the inside of the shell." The lower row wrapping the head at brow level is a credible read of "an arm … extend[ing] around the opposite temporal portions of the user's head."
Why it still does not anticipate claim 2: the air-fill element is a short, integral stem with a built-in check valve, not "an elongated air-fill tube … sufficiently long to reach a mouth of the user for inflation when mounted in said shell," and there is no "removable closure" (Dye uses an internal check valve). The cells are also discrete pillows rather than one peripherally-sealed member with tabs.
Conclusion: Dye alone does not anticipate claims 1 or 2, but it is the reference that, combined with Milone ('015) and/or Ford ('708), makes claims 1, 2, 5 and 9 prima facie obvious.
Source: https://patents.google.com/patent/US2759186

5. US 2,803,015 (Milone, "Inflatable hat") — supplies the mouth-inflation element

Confirmed text: two thin plastic (vinylite) plies; concentric intermediate seams "interrupted at predetermined locations … to provide openings affording fluid communication between adjacent passages"; a mouthpiece 14 for oral inflation; a valve; "the channels … are each rapidly inflated." That is a mouth-inflatable, seam-interrupted, communicating-channel, two-ply sealed plastic article.

• Reads on: claim 1/2's "elongated air-fill tube … sufficiently long to reach a mouth of a user" and the interrupted-seam communicating-passage structure.
• Missing for § 102: no rigid shell, no distinct thicker non-distendable wall, no T/H shape, no anchor tabs, no head-liner cushion means. Anticipates nothing in full. It is the classic secondary reference combined with Dye.
  Source: https://patents.google.com/patent/US2803015

6. US 2,983,923 (Frieder, "Rigging for protective helmet")

Helmet suspension/rigging. Relevant only to claim 8 (supporting straps … anchoring tabs … fastening means … vertical arm held spaced from the shell's inside curvature) and to the general shell-suspension context of claims 2/9. Not inflatable; anticipates nothing. Confidence: medium — identity/dates verified, text not retrieved in this session.

7. US 3,039,109 (Electric Storage Battery Co.) — second-closest reference

Confirmed text: a rigid safety helmet ("aluminum, phenolic … or plastic … fibre glass") lined with "a plurality of pads … filled with fluid," i.e. air or liquid; pads "interconnected by small tubes … to provide fluid intercommunication between the pads, also to provide a predetermined amount of restriction or control of the flow"; pads made of flexible vinyl plastic, "the thickness of which may be varied in accordance to the yieldability or stretchability desired"; pads uniformly distributed over the entire inner surface.

• Reads on: claim 2's fluid cushion means mounted inside a rigid shell; the intercommunicating-cushion concept; and the notion of variable wall thickness in the liner.
• Missing for § 102: discrete pads (not one peripherally-sealed T/H member), no mouth-reachable tube (filling/bleed valves are later "removed or pinched off … or otherwise sealed"), no anchor tabs. Anticipates nothing in full; strong § 103 art for claim 2's shell-plus-cushion combination.
  Source: https://patents.google.com/patent/[US3039109A](/patent/US3039109A)

8. US 3,168,382 (Sunbeam Corp., "Hair drier improvements") — anomalous citation

This is a hair-drier reference in a helmet-liner case. It is almost certainly present for a sub-feature (a flexible/inflatable film hood, distributed air channels, or a valve/cap), not for the headgear combination. Anticipates nothing. ⚠️ Flag: this is the weakest and most out-of-field citation in the set; I could not retrieve its text in this session, so I state its relevance as inferred-from-title and explicitly low-confidence rather than speculating on specific correspondence to a claim.

9. US 3,221,340 (Park Plastics, "Harness in combination with a rigid hat")

Shell-plus-harness mounting art. Bears on claims 2 and 9 (assembly mounted within a rigid shell) and generally on claim 8. No inflatable member, no compartments, no mouth tube. Anticipates nothing. Confidence: medium.

10. US 3,440,660 (Krinke, "Storable protective headgear")

Storable/collapsible protective headgear — the likely reason for citation is an inflatable or collapsible headgear that can be stored flat, i.e. general § 103 art against claim 1's inflatable liner concept. Anticipates nothing. Confidence: medium — text not retrieved.

11. US 3,551,911 (George Frost Co., "Protective helmet and method of making same") — § 102(e) only

Because it issued 1971-01-05, i.e. after the '704 filing date of 1970-07-13, it cannot be § 102(a)/(b) art. It qualifies only as § 102(e) art (granted on an application — filed 1969-02-04 — before the '704 inventors' date). It is a shell-plus-pad helmet and method reference, most relevant to claim 2's assembly-in-shell and claim 9's bonding/mounting of cushion means, and to claim 14's envelope/cushion. Anticipates nothing. Confidence: medium — relied on title/assignee/known subject matter.

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3. Net § 102 conclusion by claim

§ 103 groupings (where the cited art actually bites):

• Claims 1, 2, 5, 9: Dye '186 (shell + intercommunicating cells + interrupted seals) in view of Milone '015 (mouth-inflation tube) and Ford '708 (thicker non-distendable wall).
• Claims 2, 9: add '109 (fluid pads mounted in a rigid shell; variable wall thickness) and Park '340 / George Frost '911 (§102(e)) for the shell-and-pad assembly.
• Claim 8: Frieder '923 and/or Park '340 for strap/suspension mounting; '109 for the intercommunicating-cushion concept.
• Compartment/seal-manufacture: Mörner '764 and Milone '015.

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4. References the specification itself discusses but the examiner did not cite

This is the analytically important gap. The '704 specification expressly acknowledges:

• US 3,248,738 — elastomeric blocks/cushions bonded to the inside curvature of the shell (directly relevant to claim 9's "held thereto by a plurality of bonding points").
• US 3,039,109 — cited.
• US 3,186,004, US 3,462,763, and US 3,254,883 — described by the applicant as air-filled liners where "communicating conduits form a close fitting crown … between the head and the shell." That is substantially the inventive concept of claims 1 and 2, stated by the applicant in his own specification, and none of these three appear on the face of the patent. US 3,462,763 ("Impact absorbing protective headgear") appears in the Google Patents "Similar Documents" set.

Implication: the references most directly on point for the core "communicating-compartment air liner in a rigid shell sized to the head" idea were disclosed by the applicant but not relied upon by the examiner, while out-of-field art (Sunbeam hair drier, Abram bathing cap) was cited. For a validity analysis, these four are the references I would pull first — they are the strongest potential § 103 (and, for the crown-conduit concept, potentially § 102) art, and they are not among the 11 face citations.

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5. Number-collision caution (per your literal-interpretation rule)

Searching "3668704" surfaces unrelated identifiers that must not be conflated with US 3,668,704: JP 3668704 B2 (Honda Lock/Honda Motor, in-vehicle remote-control communication mode) and an EP 3668704 publication (Krones-related blow-molding art). Different jurisdictions, different subject matter. Similarly, US 3,761,959 (Dunning, 1973) and the Riddell/Xenith/Southern Impact/Intellectual Property Holdings documents are forward citations (later patents citing '704), not prior art to it.

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6. Confidence and method

• High confidence: patent identification, bibliographic data, full claim text, and the 11 face citations with their filing/issue dates (from the authoritative record and mirror).
• High confidence (text verified this session): Ford '708, Dye '186, Milone '015, Electric Storage Battery '109.
• Medium confidence (identity/dates verified, interior disclosure inferred from title/field): Mörner '764, Abram '802, Frieder '923, Sunbeam '382, Park Plastics '340, Krinke '660, George Frost '911. I searched several of these and could not retrieve full text for all of them in this session; where I could not, I have said so rather than asserting specific claim correspondence. In particular, I did not verify the Sunbeam '382 disclosure and flag it as anomalous.
• § 102 bottom line: no cited reference anticipates any claim of US 3,668,704 singly; the art is § 103 material, with US 2,759,186 (Dye) as the primary reference. Confirmatory step for a legal conclusion would be full-text review of the medium-confidence references and, separately, of the applicant-disclosed but uncited US 3,186,004 / 3,254,883 / 3,462,763 / 3,248,738.

I'll ground each prior-art reference before building the § 103 combinations.

Strong grounding so far — Ford's thick-wall bladder and Dye's interrupted heat-seals are directly on point. Let me pull the remaining cited references.

Obviousness Analysis — US 3,668,704 (35 U.S.C. § 103)

Scope note. US 3,668,704 expired 1989‑06‑13 and is not subject to live challenge. This is a retrospective validity/art analysis of the kind performed (a) in an IPR-style paper study, or (b) to understand what the '704 disclosure contributes as prior art against later helmet patents. It is not a live-controversy opinion.

Date discrepancy flagged: the system date reads 2026‑09‑30; the task header reads April 26, 2026. Nothing in this analysis turns on the difference. All prior-art dates below are pre‑1970 and unaffected.

Rule compliance: identifiers are reproduced literally. No patent number is auto-corrected. The OCR artifacts in the granted text ("wihtin," "saidcushion," "The inflatable T-shaped like") and the defective dependent-claim cross-references flagged in the previously generated summary (claim 4 reciting "as in claim 4"; claim 10 reciting "as in claim 11"; claim 11 reciting "as in claim 12") are carried through unchanged. The unrelated JP 3668704 B2 and EP 3668704 documents noted earlier are not conflated with this US patent.

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1. Legal framework

• Statute: pre‑AIA § 103 (application filed 1970‑07‑13; granted 1972‑06‑13). The AIA's "reasonably pertinent to the particular problem" standard does not apply.
• Graham v. John Deere four-factor test: scope/content of prior art; differences; PHOSITA level; secondary considerations.
• KSR Int'l v. Teleflex (2007) rationales apply to this art, which is a mature, crowded field of ordinary mechanical/thermoplastic construction: (a) known elements combined by known methods to yield predictable results; (b) simple substitution of a known element; (c) known technique improving similar devices in the same way; (d) predictable variation of a known device ready for improvement; (e) "obvious to try" within a finite, predictable set of solutions.
• The § 103 answer does not depend on the priority-date ambiguity flagged earlier. If some claims take the CIP parent's 1970‑02‑19 date, references dated between 1970‑02‑19 and 1970‑07‑13 would drop out — but none of the 11 references of record falls in that window. All are § 102(b) art as of either date (earliest issue date 1969‑04‑29 for US 3,440,660; latest, US 3,551,911, issued 1971‑01‑05 and therefore rests solely on § 102(e), its 1969‑02‑04 filing predating both candidate constructive reduction dates). The art set is stable.

PHOSITA level: a mechanical designer of athletic/industrial helmets with working knowledge of heat‑sealable thermoplastic sheet fabrication (vinyl/PVC bladders), helmet suspension rigging, and elastomeric foam padding. No advanced or unpredictable science is involved.

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2. The prior-art set: what each reference supplies

Content verified by full text where noted; otherwise content is unverified by me and the reference is used only for the subject matter the '704 specification itself attributes to it (the specification's own characterizations are admissions).

Key observation: the two structural features the '704 specification presents as novel — (i) a bladder with one wall deliberately thicker/support-side and (ii) communicating cells made by interrupted heat seals — are each disclosed, expressly and in the same problem context, by a reference already of record (Ford '708; Dye '186). That is the strongest single fact in this analysis.

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3. Independent claim 1 — element mapping and combination

Claim 1 (as printed, with its comma splice construed as a conjunctive list of elements): inflatable T-shape member; two T-conforming sidewalls; one sidewall substantially thicker, the thicker being a substantially non-distendable support wall; anchoring tabs along the peripheral margin of the arms with fastening means; sidewalls sealed along peripheral edges; horizontal arm reaching opposite temporal portions to about the medial line of the forehead; vertical arm; elongated air-fill tube between the sealed sidewalls, long enough to reach the wearer's mouth; communicating compartments via discontinuous seal lines.

Combination 1 (primary): Ford '708 + Dye '186 + Milone '015.

• Motivation: all three address the same problem — cushioning and fitting a rigid head shell against blows using a sealed, air-inflatable element, with Ford and Dye both specifically in safety/athletic helmets. Dye expressly seeks adjustability to the wearer, which is the '704 sizing objective; Milone supplies mouth inflation, which is Dye's stem adapted to a worn helmet.
• Predictability: combining a differentially thick wall (Ford) with communicating cells (Dye) and a mouth-reachable fill tube (Milone) is the mechanical union of three known, non-interfering expedients; the expected result (a bladder that inflates toward the shell, distends uniformly with less air, and can be filled by the wearer in place) is exactly the sum of the parts, with no unpredictable interaction.
• KSR hooks: (a) known elements/known method; (b) simple substitution of a thick support wall for a uniform wall to control distension direction; (d) predictable variation of a helmet bladder ready for improvement.
• Result: claim 1 obvious. The only element not squarely in Ford/Dye/Milone — anchoring tabs with fasteners — is supplied by Frieder '923 or Park Plastics '340 and, failing that, is an ordinary mechanical expedient (Ford already secures liner straps into a helmet).

Combination 1a (alternative): '109 + Dye + Milone + Ford. The '109 patent already places interconnected fluid-filled pads over the entire inner shell; shaping those pads into a T (temporal band + crown band) and choosing air with a thicker shell-side wall is a predictable rearrangement, reinforced by the specification's own admission of crown-conforming communicating-conduit liners.

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4. Independent claim 2 and its dependents

Claim 2 is broader in geometry (any "arm" long enough to reach the temporal regions to the forehead medial line) but adds (a) a removable closure on the fill tube, (b) the communicating-compartment/discontinuous-seal limitation (same as claim 1), and (c) cushion means along both opposite sidewalls, serving both to cushion and to mount the member to the shell interior.

Combination 2 (envelope-centric): Morner '764 + Dye '186 + admitted foam-block art. Morner supplies the sealed-ply envelope and the interrupted-seal venting method; Dye supplies a helmet-context communicating-cell cushion; the admitted '738 art supplies the elastomeric covering. Motivation: obtain a replaceable, washable, foam-faced cushion that also sizes the helmet — the exact two-in-one benefit stated in the '704 abstract.

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5. Why a PHOSITA would have combined these — stated motivations

1. Same field, same problem, same materials. Ford ('708), Dye ('186), '109 (Simpson/ESB), Frieder, Park Plastics and the admission-cited '738, '186-type references all address cushioning a rigid head shell, all with sheet-plastic/rubber inflatables or elastomeric padding. There is no field-crossing leap; no reference must be imported from a remote art.
2. The additional references solve the very sub-problems the '704 specification recites as its objects. Dye/Morner answer "uniform distention with smaller volumes of air"; Milone answers "fill by mouth while worn"; Ford answers "don't let the cushion bind the head or block ventilation" and "support the shell in spaced relation."
3. The field was crowded and the solution set small. A bladder inside a hard shell can be (i) compartmented or not, and if compartmented, (ii) sealed cell-by-cell or (iii) communicating; a liner can be a single band, a T, or an H; it can be bare or foam-faced. Every one of these is either exemplified by a pre-1970 reference or admitted in the '704 specification. Under KSR, that finite, predictable menu supports "obvious to try."
4. Manufacturing predictability. Heat-sealed vinyl bladders with interrupted seams were a mature 1950s consumer-goods technique (Morner, Milone, Dye). Applying it to a helmet liner yields no new operability question.
5. No teaching away. Nothing in Ford, Dye, '109, or Milone disparages compartmentation, mouth inflation, foam facing, or differential wall thickness; Ford affirmatively teaches the differential wall and the spaced crown suspension.

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6. The best non-obviousness arguments (and my assessment)

Also worth noting (not a validity argument): several dependent claims are unenforceably drafted — claim 4's self-reference ("as in claim 4"), claim 10's "as in claim 11," claim 11's "as in claim 12," plus the OCR/claim-text truncation in claim 1. On their face these cross-references are defective; they do not improve the claims' position under § 103 and, if anything, make them easier to read broadly (which increases anticipation/obviousness exposure for claims 4, 10, and 11).

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7. Conclusion

Independent claim 1 — should be held obvious over Ford US 1,833,708 in view of Dye US 2,759,186 and Milone US 2,803,015 (optionally with Frieder US 2,983,923 or Park Plastics US 3,221,340 for the anchoring tabs). Confidence: high. Ford supplies the thick non-distendable support wall and the shell-directed expansion; Dye supplies the heat-sealed vinyl cells with interrupted seals providing inter-cell passages in a helmet context plus the fill stem/closure; Milone supplies the mouth-reachable fill tube and removable closure. The T geometry is the principal gap, and it is substantially closed by '109 (pads over the entire inner shell) and by the applicant's own specification admissions.

Independent claim 2 — should be held obvious over Dye + Milone + the applicant-admitted US 3,248,738/'109 art for the both-sidewall cushion/mount means. Confidence: high.

Claim 8 — the closest call. Ford's right-angle crown straps secured to the helmet "in a slight spaced relation thereto" is functionally the claimed suspension mounting. Confidence: moderate-high depending on the unverified content of Frieder '923 / Park Plastics '340.

Claim 6 — possible § 102 exposure, not merely § 103, if Dye's single row of communicating pillows with inner/outer walls and a fill stem is treated as the claimed unbranched single arm with cushion means on both sidewalls. Confidence: moderate (claim-construction dependent).

Claims 3–5, 7, 9–16 — obvious under the combinations tabulated in § 4. Confidence: moderate to high, with claim 11 (shell edge profile) and claim 16 (H-shape envelope) resting on design-choice/predictable-variation reasoning and therefore carrying the lowest confidence.

Overall verdict: the '704 claims would very likely have been rejected under § 103 had Ford, Dye, and Milone been applied in combination. The patent's contribution appears to lie in the aggregation and helmet-specific shaping of individually known expedients rather than in any new mechanism — and the two features its specification describes as inventive (differential wall thickness; communicating compartments from interrupted seals) are each expressly disclosed in the references of record.

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8. Confidence, gaps, and caveats

• Verified by full text this session: US 1,833,708 (Ford), US 2,759,186 (Dye), US 2,803,015 (Milone), US 2,575,764 (Morner), US 3,039,109 (Simpson / Electric Storage Battery Co.). Sources: patentimages/Google Patents PDF and HTML at https://patents.google.com/patent/US1833708A/en, https://patentimages.storage.googleapis.com/c6/2f/a2/47e350d6d52e1c/US2759186.pdf, https://patents.google.com/patent/US2803015, https://patentimages.storage.googleapis.com/92/95/60/cee970f860fb87/US2575764.pdf, https://patents.google.com/patent/US3039109A.
• NOT verified by me in this session (content asserted only for the role assigned by the '704 specification/face citations): US 2,033,802 (Abram), US 2,983,923 (Frieder), US 3,168,382 (Sunbeam), US 3,221,340 (Park Plastics), US 3,440,660 (Krinke), US 3,551,911 (George Frost Co.). My searches for these returned no usable text before the session's tool-step limit was reached. Statements about what these six teach are inferences from their titles and from the examiner's citation of them, not from verified text. Anyone relying on Combination 1's tab/fastener mapping or claim 8's outcome should pull the full text of Frieder '923 and Park Plastics '340 first.
• Secondary-consideration evidence: none located. If commercial-success or long-felt-need evidence exists for the '704 design, it was not in the provided record and is not reflected above.
• Methodology limit: this is a paper § 103 analysis on a fixed art set (the patent's own face citations plus specification-cited references), not an independent worldwide prior-art search. Broader art (e.g., 1960s inflatable-splint, life-vest, and air-mattress compartmentation patents not cited on the '704 face) would likely strengthen, not weaken, the obviousness position on the compartment and closure limitations.
• No identifier corrections were made. OCR-degraded text and defective internal claim cross-references are reproduced as granted. The JP 3668704 B2, EP 3668704, and 2020 WL 3668704 documents identified earlier remain distinct from this US patent and play no part in this § 103 analysis.