US 3682609

I'll run targeted searches for the literal number 3682609 in USPTO and CAFC contexts.

Search scope and hit confirmation

Searches were run for the literal string 3682609 against patent-database and court-docket sources. The only US patent matching that number is the one requested. Because the instruction is literal interpretation, two disambiguation notes up front:

• A different, unrelated document shares the digits 3682609: JP3682609B1 — "Hair bundle for thickening hair and method for attaching the same" (a hair-extension patent). That is not the patent you asked about and is excluded.
• Internal number discrepancy in the source text: the authoritative full text labels the patent 3,682,609 throughout (headers, patent-number field, claim text), but one drawing-sheet header in the same document reads 3,632,609. I am not auto-correcting it; I read it as a scan/OCR artifact of the same document, since every other instance and the bibliographic record give 3,682,609.

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Bibliographic summary — US 3,682,609 (number as requested: 3682609)

Foreign family (same invention, other jurisdictions): BE757057A; ES381914A1; FR2064155B1; GB1277397A; JPS5440566B1.

References cited on the face: FR1447205A (Saint-Gobain, 1965); DE1596402A1 (Corning Glass Works, 1967); plus a Belgian patent (7/1968) and a British patent (12/1968) named without numbers in the OCR text. The specification itself cites US 1,829,641 and US 3,338,696 as known overflow-downdraw forming constructions.

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Abstract (verbatim from the record)

"Variation in temperature profile across the width of newly formed glass sheet produces objectionable thickness variations which adversely effect optical quality. Precision control of the temperature profile across the width of newly drawn sheet glass is obtained through the provisions of a plurality of closed spaced, individually regulated fluid control jets or tubes positioned across the width of such sheet within a closure with the exit ends of such tubes being shielded from the glass by means of a wall member having high conductivity, low expansion, and high emissivity."

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Independent claims in plain language

The patent has 10 claims total: two independent (claim 1, method; claim 5, apparatus) and eight dependent (2–4 depend on 1; 6–10 depend on 5).

Claim 1 — Method of controlling sheet thickness across the width of newly formed glass sheet

• Direct multiple individual gaseous streams toward the molten material that forms the sheet.
• The streams impinge across the width onto the back surface of an uninterrupted wall member placed between the streams and the newly formed sheet.
• Two structural conditions on that wall: (a) its back surface is free of contacting elements across the sheet width, and (b) the wall has high thermal conductivity, low expansion, and high emissivity.
• All the gas is contained in a single enclosure, so it never reaches the newly formed sheet.
• Then individually control the flow rate of each stream across the width to selectively pull heat out of the wall — heat that the wall first absorbed from the glass and conducted through to its back surface — thereby yielding a uniform temperature profile and uniform sheet thickness.

Claim 5 — Apparatus for controlling thickness uniformity across the width of newly formed sheet glass

• A housing positioned adjacent the molten material forming the drawn sheet.
• A front wall with an uninterrupted back surface, spanning the effective width of the sheet.
• Mounting arranged so the back surface, except at its bounding borders, touches no structure that would cause thermal discontinuity across the drawn width.
• Multiple fluid conduit tubes inside the housing, arranged in a row across the front wall's width — the housing defines a single enclosing chamber for these tubes.
• Each tube's outlet end faces and is spaced from the front wall's back surface.
• A manifold supplies pressurized gas to the tubes, with means to individually regulate the flow rate through each tube.
• The front wall is made of a low-expansion material with relatively high thermal conductivity and emissivity, so it absorbs heat from the newly formed sheet and conducts it through the wall for dissipation, in response to the individually regulated gas streams impinging on its back surface.

Dependent-claim coverage worth noting: selective heating of certain gas streams (cl. 2, 7); varying the impingement area/intensity by moving tubes relative to the wall (cl. 3, 9); staggered tubes on both sides of the sheet at equal spacing (cl. 4, 6); silicon carbide front wall (cl. 8); contoured outlet ends with patterned discharge openings (cl. 10).

Worked example in the specification: a glass per British Patent No. 966,733 drawn over a forming wedge at ~1,700 lb/hr and ~50 in/min to a ~60-inch usable width and ~0.070-inch thickness; ~1-inch-spaced tubes (staggered to give ~½-inch effective control spacing) behind a 1-inch silicon carbide slab with outlets ~⅛ inch behind the slab, ~7 inches laterally from the glass, air at 1½ p.s.i.g. from a manifold, valves regulated 0–50 c.f.h. Result stated: thickness variation held to within .00018 inch per inch of width.

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Uncertainty / diligence notes

• No CAFC 2026 docket hit. Searches of Federal Circuit 2026 docket/appeal material returned nothing naming 3,682,609. This is consistent with the record showing the patent expired 1989-08-08 (17-year term from 1972), i.e., it has been off-term for decades. I cannot state categorically that no case anywhere ever referenced it, but no 2026 CAFC activity is evidenced.
• Litigation relevance is by citation, not by suit. The patent appears in later proceedings only as cited prior art / incorporated-by-reference subject matter. Example: RPX litigation documents quoting an overflow-downdraw patent that criticizes US 3,682,609's control zone as capable of redistributing glass only over "about 5–10 cm," and CN100534938C contains the same criticism.
• Terminology legacy. Later Corning filings refer to this disclosure generically as the "Dockerty system" and to its flow tubes as "Dockerty tubes" — e.g., US 8,196,431 ("the Dockerty patent (i.e., U.S. Pat. No. 3,682,609) is incorporated herein by reference in its entirety") and US 8,627,683. This confirms (a) the number mapping 3682609 ↔ 3,682,609 and (b) inventor attribution to Dockerty.
• OCR artifacts in the provided text. Several numeric specifications in the description are garbled (e.g., silicon carbide thermal conductivity/expansion values rendered as "110 at 1200 C." and "45 X 10"). I have deliberately not restated those values as fact. Likewise, the drawing-sheet header reading "3,632,609" is flagged above rather than treated as a separate patent.
• Dates are given exactly as the record states them (filed Oct. 6, 1969; granted Aug. 8, 1972). Per your instruction, no identifiers have been normalized or auto-corrected.

Primary sources: Google Patents full text — https://patents.google.com/patent/US3682609/en ; PDF facsimile — https://patentimages.storage.googleapis.com/d5/60/7e/d4fa7d83887615/US3682609.pdf ; corroborating later citation in US 8,397,536 B2 (https://patentimages.storage.googleapis.com/25/eb/c5/d0674140cf56b9/US8397536.pdf).

I'll search for litigation involving this specific patent number.

Let me search litigation-specific databases.

Let me try a few more targeted litigation sources.

Litigation Search Results — U.S. Patent No. 3,682,609

Bottom line: I found no evidence of any litigation involving U.S. Patent No. 3,682,609.

I was unable to identify any district court action, ITC investigation, PTAB proceeding, or Federal Circuit appeal in which U.S. Patent 3,682,609 was asserted or challenged. Every hit returned for the literal string "3682609" was either the patent's own bibliographic/OCR record or a citation to the patent as prior art or background literature, not a litigation document. Specifically, the only substantive hits were:

None of these is a court or agency docket for the '609 patent itself.

Why this result is expected

• Patent term: Filed October 6, 1969 (Ser. No. 863,885); granted August 8, 1972. Under the pre-URAA 17-year term, the patent expired August 8, 1989 (Google Patents lists "Anticipated expiration 1989-08-08," legal status "Expired – Lifetime"). Any assertion window closed more than 35 years ago.
• Nature of the technology: This is a manufacturing-process patent (individually controlled air jets impinging on a high-conductivity, low-expansion, high-emissivity silicon carbide wall to control glass sheet thickness). The "Dockerty system"/"Dockerty tubes" it describes became a standard, widely practiced element of Corning's fusion downdraw process — the classic posture for cross-licensing or internal practice rather than litigation.
• Family: Corresponding foreign members (GB1277397, FR2064155, BE757057, ES381914, JPS5440566B1) show routine prosecution, not enforcement activity.

Important limitations on this answer

• I could not directly query PACER, CourtListener/RECAP, the Unified Patents litigation caselist, Docket Alarm, or RPX in a way that returned a definitive negative for this specific number; my search tooling returned only patent-literature hits and then reached its query limit.
• Pre-1989 docket records are poorly digitized, so an old 1970s–1980s infringement suit against, e.g., a foreign glassmaker, could plausibly escape modern full-text search. I cannot rule that out with high confidence.
• Accordingly, my statement is: no litigation is known to me and none was found in the sources searched, rather than a categorical assertion that none ever existed.

Recommended verification steps

If a litigation-clearance-grade answer is needed, I would check:

1. Docket Alarm / Unified Patents litigation portal filtered strictly to patent number 3,682,609 (which I was unable to complete).
2. Westlaw/Lexis federal district court dockets and the Federal Supplement / USPQ digests for 1972–1989, searching "3,682,609" and "Dockerty."
3. Corning Incorporated corporate litigation history and any 1970s–80s license/consent-decree records.

Per the operating rules, I am flagging this as an area where I do not have high-confidence knowledge and am not fabricating case names, case numbers, or outcomes to fill the gap. If you can point me to a specific docket or let me run additional targeted searches (e.g., CourtListener RECAP API), I can verify further.

I'll verify the structured block against public sources before answering.

PTAB Activity Report — US 3,682,609 ("Controlling thickness of newly drawn glass sheet")

Patent: US 3,682,609 A · Inventor Stuart M. Dockerty · Original assignee Corning Glass Works (Corning Incorporated)
Application: US 863,885 · Filed 1969-10-06 · Granted 1972-08-08 · Anticipated expiration 1989-08-08 (Google Patents legal-status record)
Claims: 10 total — claims 1–4 (method), claims 5–10 (apparatus)
Source of record: https://patents.google.com/patent/US3682609/en

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Proceedings overview

Total AIA trial proceedings on file against US 3,682,609: zero (0) — 0 IPRs, 0 PGRs, 0 CBMs. Breakdown by status: 0 active, 0 claims invalidated, 0 claims sustained, 0 settled, 0 institution denials. My independent web checks (searches for the patent number in combination with IPR/PGR/PTAB petition terms, and a petitioner-side search) surfaced no petition, institution decision, FWD, or Federal Circuit appeal naming this patent as the challenged patent — consistent with the USPTO ODP structured record in the prompt.

The bottom line for a defendant is not "the patent has survived IPRs and is hardened" and not "claims have been canceled." It is: there is nothing left to defend against. The patent expired 1989-08-08 and is in the public domain. No AIA proceeding was ever needed, and none was ever filed. Any demand letter citing US 3,682,609 as a basis for current infringement is facially baseless, full stop.

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Per-proceeding detail

Not applicable — there are no proceedings to list. I am deliberately not manufacturing empty proceeding headers with invented numbers, panels, or dispositions. For completeness, the template fields would resolve as follows:

• Type: n/a — none filed
• Filed: n/a
• Status: n/a — the structured ODP record carries no trial status because no trial exists
• Judge panel: n/a
• Petition grounds: n/a
• Institution decision: n/a
• Final Written Decision: n/a
• Settlement / termination: n/a
• Appeal: n/a
• Defensive value: total. See below.

Why the absence is structural, not accidental

Three independent reasons make PTAB activity on this patent implausible rather than merely unobserved:

1. The patent expired 1989-08-08. Google Patents records the legal status as "Expired - Lifetime" with an anticipated expiration date of 1989-08-08 (17 years from the 1972-08-08 grant). AIPLA/PTAB economics: no one pays six figures to invalidate a patent that cannot support an infringement verdict. The Board has repeatedly weighed the expired status of a challenged patent against institution on discretionary grounds (see the expired-patent discretionary-denial argument Corning itself advanced in the Caihong dispute over the '491 patent, https://ptacts.uspto.gov/ptacts/public-informations/petitions/[1557917](/patent/1557917)/download-documents).
2. PGR is legally unavailable. Post-grant review under 35 U.S.C. § 321 applies only to patents with an effective filing date on or after 2013-03-16. This patent's effective filing date is 1969-10-06 — 44 years too early.
3. CBM is legally unavailable. The '609 patent claims a glass-sheet forming and thickness-control process and apparatus (silicon carbide front wall, individually valved air jets, staggered housings). It does not claim a "financial product or service" or a "technological invention" used in the practice of a financial service. It fails the § 18(d)(1) AIA transitional-program definition on its face.

That leaves IPR as the only theoretically available vehicle (§ 311 does not exclude expired patents), and no rational petitioner would file one.

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Strategic summary

Claim status. All ten claims — independent method claim 1 and its dependents 2–4, and independent apparatus claim 5 with dependents 6–10 — are UNTESTED by the PTAB. That is not the same as "SURVIVED." Nothing has been reviewed, narrowed, amended, or adjudicated. More importantly, all ten claims are EXPIRED: the exclusive right they once defined ran out on 1989-08-08. There are no "surviving claims" of commercial significance, because there are no enforceable claims at all. When later patents in this family want to describe the technology, they now cite '609 as background prior art and refer to the hardware generically as the "Dockerty plate and tube system" or "Dockerty tubes" — terminology that has fully entered the art as a generic descriptor (see, e.g., U.S. 8,196,431 and U.S. 8,627,683, which incorporate '609 by reference: https://patents.google.com/patent/[US8196431](/patent/US8196431) and https://patents.justia.com/patent/8627683).

Estoppel landscape. 35 U.S.C. § 315(e)(2) estoppel is a non-issue: estoppel only attaches to a petitioner who obtained a final written decision, and no petition was ever filed, so no party is estopped as to any ground against '609. If one wanted to be pedantic, the entire universe of anticipation and obviousness art remains unburdened by estoppel. That is irrelevant in practice. Practically relevant, however, is the reverse estoppel-like effect: because '609 issued 1972-08-08 and was publicly available, its ~19 columns of disclosure (including the 1970-era working example: 1-inch-ID air tubes at 1-inch intervals, staggered ½-inch, 1″-thick silicon carbide slab, 1½ p.s.i.g. manifold air, 0–50 c.f.h. control range, ±0.00018 in/in thickness variation) have been § 102(b) / post-AIA § 102(a)(1) prior art against every later drawn-glass thickness-control claim since 1973-08-08. A defendant accused of a later thickness-control or "Dockerty tube control algorithm" patent should pull '609 and U.S. 3,338,696 (also Dockerty) into the prior-art mix on day one — they are the cornerstone references in this space and they are cited in literally hundreds of later U.S. and foreign filings.

Pattern signals. No repeat petitioner, because there was never a first petitioner. No patent-owner PTAB appeal history on this patent, because there was never a Board decision to appeal. No defensive aggregator (Unified Patents, RPX, etc.) appears anywhere in the chain — consistent with the fact that aggregators target asserted, unexpired patents, neither of which describes '609. The family record confirms the scope of activity: the '609 family has siblings in JP (JPS5440566B1), BE (BE757057A), ES (ES381914A1), FR (FR2064155B1), and GB (GB1277397A) — all foreign prosecutions, all long since lapsed. Corning's litigation and PTAB activity in the fusion-draw space has been around the much later glass-composition and processes patents (e.g., the EAGLE XG / '491 patent dispute with Caihong Display Devices), and in those matters '609 shows up as a cited reference, never as the challenged patent.

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Recommended next steps

1. If you received a demand letter citing US 3,682,609 — stop and check the term before anything else. The patent expired 1989-08-08. Activity today cannot infringe it: an expired patent confers no right to exclude (see Kimble v. Marvel Entertainment, 576 U.S. 446, 451 (2015); Sears, Roebuck & Co. v. Stiffel Co., 376 U.S. 225, 230 (1964)). Under 35 U.S.C. § 286, damages are limited to the six years preceding the complaint, so the last possible actionable damages window for this patent closed over three decades ago. A demand letter that cites '609 as a live basis for current royalties is not a licensing offer; it is a shakedown.
2. If the accusation is under a later Corning glass-sheet patent, redirect the analysis: '609 is your prior art, not their hammer. Confirm whether the asserted patent incorporates the Dockerty disclosure by reference, and whether its independent claims recite the pre-existing Dockerty structure (front wall, spaced individually controlled tubes, staggered housings) with only routine limitations added. Quote the '609 specification's working example in the invalidity contention — the specifics are unusually well documented for a 1969 disclosure.
3. Verify the null result before relying on it. The ODP ingest date in the prompt is the operative cutoff. Confirm directly:
   • PTAB E2E / PTAB Decisions search by patent number: https://developer.uspto.gov/ptab-api/ and the public UI at https://ptacts.uspto.gov/
   • USPTO Patent Center for the '609 file wrapper: https://patentcenter.uspto.gov/
   • USPTO Open Data Portal API, patentOwnerData.patentNumber = 3682609: https://data.uspto.gov/
     A zero-match query is itself the answer here — but re-run it at the time you file anything.
4. Do not expect a future petition. Even if the ODP ingest lags by months, no filing against this patent would be economically rational, so the null result is unlikely to change on re-query.

Confidence and caveats

• High confidence: zero AIA trial proceedings against US 3,682,609; patent expired 1989-08-08; PGR and CBM legally unavailable on this patent's face.
• Moderate confidence: no ex parte reexamination or other post-grant action against '609. I did not find one, but I did not run a Patent Center reexam-search directly, and the ODP/P-TACTS coverage of 1970s–1980s reexaminations is uneven. This does not change the defensive picture, since an expired patent is unenforceable regardless.
• Deliberate omission: I have not assigned proceeding numbers, judge panels, or dispositions to hypothetical or analogical cases. Each of those fields requires a real proceeding, and none exists here.

I'll research this patent's ownership record before drafting.

Let me check for any recorded change-of-name or assignment events tied to Corning and this patent family.

One more targeted check on whether Corning's 1989 name change was recorded against this patent.

Assignment & Ownership Analysis — US 3,682,609

Patent: US 3,682,609 A — "Controlling thickness of newly drawn glass sheet"
Application: US 863,885, filed 1969-10-06 · Granted: 1972-08-08 · Anticipated expiration: 1989-08-08
Sources consulted: Google Patents full text + legal events (US3682609A), USPTO Assignment Center (https://assignmentcenter.uspto.gov/), Corning SEC/corporate disclosures for name-change history, RPX / Unified Patents / NPE directories via open search.

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Inventors

Stuart M. Dockerty — sole named inventor. Residence given on the face of the patent as Corning, N.Y.; assignor to Corning Glass Works, Corning, N.Y. at filing. Employer at time of filing: Corning Glass Works (determinable from the assignment clause printed on the patent and from Corning's own corporate history, which credits "Corning scientists Stuart Dockerty and Clint Shay" with developing the fusion overflow process in 1964). Dockerty was a career Corning inventor — he is also the named inventor of the foundational fusion downdraw patent US 3,338,696 ("Sheet forming apparatus," granted 1967-08-29), which this patent cites as the known forming member.

Unusual-pattern flags: none. This is a single-inventor, in-house, employer-assigned filing. There is no record of the inventor departing the assignee within 12 months of filing, no co-inventor split, and no later inventor-side assignment activity. Absence of any post-1972 assignment record is consistent with an inventor who never recaptured rights.

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Original assignee

Corning Glass Works, Corning, New York — an operating glass and materials manufacturer, and the entity named on the issued patent via the inventor's pre-filing assignment ("assignor to Corning Glass Works").

• Product practice: Yes — strongly. The claims cover the localized thermal/thickness-control system for fusion overflow downdraw. Corning's own published corporate history states that the fusion overflow process developed by Dockerty and Shay "later becomes the manufacturing process for Corning's liquid-crystal display (LCD) glasses, Corning® Gorilla® Glass, and other industry-shaping glass innovations." Later Corning filings treat this patent as the canonical implementation of the technology — e.g., Corning's US 8,627,683 refers expressly to "a particular thermal control system (e.g., a Dockerty system)."
• Primary line of business: specialty glass, glass-ceramics, optical fiber, and display substrates (NYSE: GLW).
• Current status: Operating. Name changed from Corning Glass Works to Corning Incorporated on 1989-04-28 (per Corning's own 10-K/prospectus language). Never bankrupt, never acquired, never dissolved. Corning is currently the dominant supplier of fusion-drawn LCD/OLED substrate glass.

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Assignment timeline

Finding: no recorded assignment records exist for this patent in the sources I could reach, and the patent's own legal-events record contains no post-issuance assignment entries.

What is actually verifiable:

• On or before 1969-10-06 (executed) — reel/frame not printed on the patent and not recoverable from the sources consulted

  • Conveyance: Assignment (inventor → employer), recited on the face of the patent
  • Assignor: Stuart M. Dockerty
  • Assignee: Corning Glass Works, Corning, N.Y.
  • Correspondent: not stated on the printed patent (the drawing signature block is OCR-degraded and the prosecuting attorney's name is not legible)
  • Context: standard pre-issuance employment assignment; no commercial significance

• 1969-10-06 — Application filed

• 1972-08-08 — Application granted / patent published as US 3,682,609 A

• 1989-08-08 — Anticipated expiration (17 years from grant, pre-URAA term)

No Assignment Center record could be surfaced for this patent number: no reel/frame entries, no conveyance types, no assignors, no assignees, and therefore no assignment correspondent of record at all. Google Patents' legal-events table for US3682609A likewise lists only Application filed, Application granted, Publication of US3682609A, and Anticipated expiration — no assignment, security interest, merger, license, release, or change-of-name events.

Method caveat (stated plainly): I could not execute a live, direct query against the USPTO Assignment Center database; my verification was limited to web-indexed mirrors and secondary aggregators. A null result from those channels is not the same as a confirmed empty database return. Before treating this as final, run the patent number directly at https://assignmentcenter.uspto.gov/ and confirm the return count is zero.

One unresolved item, flagged rather than asserted: Corning Glass Works formally renamed itself Corning Incorporated on 1989-04-28, the same year this patent's term expired. Corning has historically recorded bulk Change of Name conveyances against its U.S. patent estate. I found no evidence that a change-of-name assignment was recorded against US 3,682,609 specifically, and I am not asserting one. If a Corning change-of-name reel exists covering 1989, it may or may not include this patent. A 1989 change of name would be purely administrative and would carry zero NPE significance either way — it is an internal reorg, not a transfer.

Per the research protocol, where the Assignment Center shows no records the chain analysis stops here. I am nonetheless rendering the remaining required sections so the null finding is documented in the standard schema rather than left blank — every signal below is scored against an empty record set.

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Timeline diagram

timeline
    title Ownership of US 3682609
    1969 : Application filed by Stuart M Dockerty
         : Rights assigned to Corning Glass Works
    1972 : Patent issued on 8 August 1972
    1989 : Term expires 8 August 1989
         : Corning Glass Works renamed Corning Incorporated

No post-issuance transfer node exists to plot. The 1989 rename node reflects a corporate name change, not a recorded assignment against this patent.

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NPE / troll-pattern signals

1. Shell-entity transfer — not present. No assignment records exist. The last and only identifiable owner is Corning Glass Works / Corning Incorporated, the original operating manufacturer, at one Riverfront Plaza, Corning, NY 14831. No "IP / Patents / Licensing / Holdings / Ventures" successor appears anywhere in the record.

2. Known asserter in the chain — not present. No assignee in the chain matches Acacia, Marathon, Intellectual Ventures, IPNav, Wi-LAN, Mosaid/Conversant, Vringo, Pendrell, Innovatio, MPHJ, Lumen View, Round Rock, Document Generation Corp, or any Spangenberg-affiliated entity. No Unified Patents or RPX high-frequency-plaintiff hit surfaced for this patent number.

3. Repeat correspondent across the chain — not present (vacuous). There are no assignment correspondents of record to compare, because there are no recorded assignments. Note for context, and not as a finding: Corning's Patent Department (SP-TI-3-1, Corning, NY 14831; e.g., correspondent Thomas R. Beall on Corning reel 018028/0949, recorded 2006-06-28) is the recording correspondent on unrelated, much later Corning patents. That is a single-company in-house patent department doing routine corporate recordation — explicitly not a repeat-NPE-correspondent signal, and it does not appear on this patent.

4. Cascading transfers — not present. No consecutive chained assignments; no LLC-to-LLC hops; no shared-correspondent-address pattern. There is one link (inventor → Corning Glass Works) and nothing after it.

5. Pre-litigation transfer — not present. No assignment within 6 months (or any period) before an infringement suit. No litigation events are listed for this patent, and the patent has been expired since 1989-08-08, so assertion is legally impossible today.

6. Bankruptcy fire-sale — not present. Corning Glass Works / Corning Incorporated never filed Chapter 7 or Chapter 11, and there is no sale-of-estate conveyance in the record.

7. Privateering — not present. No operating-company-to-NPE transfer; Corning retained the patent and practiced the technology itself (fusion draw for display glass and Gorilla Glass).

8. Defensive aggregator (anti-NPE) — not present. The chain does not terminate at RPX, AST, LOT Network, Unified Patents, or OIN. It terminates at expiry in 1989 while still held by the original operating assignee.

Aggravating note on subject matter: the family is a single application with foreign counterparts only (BE 757057, FR 2064155, GB 1277397, JP JPS5440566B1, ES 381914) — no continuation or divisional chain, and therefore no opportunity for a late-filed continuation to be diverted to an asserter. The patent's extraordinarily large forward-citation set (257+ in the Google Patents "Cited By" table, overwhelmingly Corning's own later filings) reflects its role as foundational prior art for Corning's display-glass franchise, not licensing activity.

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Verdict

Insufficient data — no recorded assignments exist beyond the original pre-issuance assignment to Corning Glass Works, and the patent expired 1989-08-08.

Justification: Google Patents legal events for US3682609A contain only Application filed (1969-10-06), Application granted (1972-08-08), and Anticipated expiration (1989-08-08) — no reel/frame entries of any kind, so there are zero assignment correspondents to test for recurrence. The sole identifiable assignee is the original operating manufacturer, Corning Glass Works (now Corning Incorporated), which commercially practiced the claimed fusion-draw thickness-control technology. Substantively, this patent poses no NPE exposure: it is an expired 1972 grant, prior art only, and cannot be asserted by anyone. Caveat as noted above — confirm the empty Assignment Center return with a direct query before treating the null finding as definitive.

I'll research this systematically. Let me start with searches for the patent and its cited references.

I found the actual "References Cited" list from the patent PDF. Now let me research each cited reference individually.

I hit the tool-use limit partway through verification. Here is my report, built on the authoritative "References Cited" list I retrieved from the granted patent itself, with clear flags on what remains unverified.

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Prior Art Analysis — US 3,682,609

Patent: US 3,682,609 A — "Controlling thickness of newly drawn glass sheet"
Inventor: Stuart M. Dockerty | Assignee: Corning Glass Works
Filed: 1969‑10‑06 (Ser. No. 863,885) | Granted: 1972‑08‑08
Art unit: C03B 17/06 (overflow downdraw fusion); Primary Examiner: Arthur D. Kellogg
Status: Expired – Lifetime (anticipated expiration 1989‑08‑08)

1. Source of the citation list

The Google Patents web rendering of this patent drops the body of the "References Cited" table (only the "FOREIGN PATENTS" fragment survived in the fetched text). However, the facsimile PDF of the printed patent (front page, column 2) contains the complete list, which I retrieved:

UNITED STATES PATENTS

FOREIGN PATENTS

U.S. Cl. X.R.: 65‑95, 203, 204, 327. Source: https://patentimages.storage.googleapis.com/d5/60/7e/d4fa7d83887615/US3682609.pdf

Note on the printed "X" convention: in U.S. patent front pages of this era an "X" appended to the classification denotes an examiner cross‑reference (a patent bearing on the subject matter but classified elsewhere), not a legal conclusion of anticipation. I interpret these identifiers literally and do not reclassify them.

2. Reference-by-reference analysis

2.1 US 1,829,640 — Ferngren (10/1931), class 65‑53

• Description (from the art, verified in this session via the closely related Ferngren/Libbey‑Owens family): an early overflow/downdraw sheet-glass forming method and apparatus in which molten glass flows down both faces of a refractory slab or wedge, the two streams merging at the lower end and being drawn as a unitary sheet. The sibling Ferngren disclosure I retrieved (US 1,829,641, "Method and apparatus for drawing sheet glass," Libbey‑Owens) claims a slab with means "to build up a reservoir of glass … to make uniform the thickness of the stream after it leaves the reservoir," i.e., temperature/thickness equalization of the down-flowing streams. I did not retrieve the text of 1,829,640 itself, so the description above is inferred from the family and the cited class; treat the specific content as unverified.
• §102 relevance: This is the closest item to the preambular environment of claim 1 (a downdraw/fusion sheet-forming operation) and the antecedent of the "overflow downdraw forming member 10 … of known construction" that the specification cites. It contains no gas-jet array, no enclosed cooling chamber, and no high-emissivity front wall. Accordingly it cannot anticipate claims 1–10 individually; it is at most background art bearing on the field of the invention and would figure in a §103 obviousness rationale, not §102.
• Claims potentially affected: none as a standalone anticipation.

2.2 US 3,240,584 — Zellers (3/1966), class 65‑205 X

• Status of verification: NOT VERIFIED. My search for this number returned no results before I reached the tool limit, so I will not state a title or disclosure for it. What is verifiable from the face of US 3,682,609 is only: granted 3/1966, inventor Zellers, cited against class 65‑205 with an examiner cross-reference "X."
• What can be said responsibly: class 65‑205 in the U.S. classification of that era covered glass-working processes/means for temperature-conditioning and cooling a newly formed sheet. A reference placed here by the examiner is the type of art most likely to bear on claim 1's "controlling the amount of flow … to selectively remove heat" and on claim 5's housing/manifold structure. I therefore flag it as the highest-priority reference to verify for a §102 attack on claims 1, 3 and 5, and I will not assert more than that.
• Action needed: retrieve the full text/claims of US 3,240,584 to complete the §102 mapping.

2.3 US 3,244,498 — Green et al. (4/1966), class 65‑356 X

• Status of verification: NOT VERIFIED. My search returned no usable content for this number. Verifiable from the face of the patent: granted 4/1966, "Green et al.," cited against class 65‑356 with an examiner cross-reference.
• What can be said responsibly: class 65‑356 in that era covered glass sheet/ribbon drawing apparatus, including cooling and attenuating apparatus. This is the reference most likely to bear on claim 4 (plurality of streams "in staggered relationship toward both sides of said newly formed glass sheet") and claim 6 (housings on each side, tubes "equally spaced apart in staggered relationship"). Flagged as the second-highest priority reference to verify.
• Action needed: retrieve full disclosure before any §102 conclusion.

2.4 US 3,506,429 — Overman (4/1970), class 65‑203

• Status of verification: PARTIALLY VERIFIED. The number, date, inventor and class come directly from the granted patent's face, which I did retrieve. I did not retrieve the reference's own text in this session; the tool-limit message terminated the query.
• Date caveat (important): its publication date (4/1970) is after the 1969‑10‑06 filing of US 3,682,609. Under pre‑AIA 35 U.S.C. §102, a U.S. patent publishing after the applicant's filing can only be prior art under §102(e) — i.e., if its application was filed before the Dockerty invention/filing date. Whether that is so is not established by the front page alone. A §102(e) assertion against claims 1–10 would require the Overman application's filing date.
• Relevance: classified 65‑203 (drawing of sheet glass with temperature control), it is the reference most likely to be directed at localized cooling/attenuation control of a newly drawn sheet, i.e., potentially to claim 1 and to claims 5/9 (the housing and the means for moving conduits toward and away from the back surface). Note that Overman is a recurring name in the sheet-glass-drawing art of this period (cf. US 3,437,470 Overman, also listed as a citation in Corning's later filings), so the subject matter overlap is plausible — but plausible is not verified.

2.5 Belgium 708,848 (7/1968)

• Status of verification: NOT VERIFIED. No content retrieved. Verifiable from the face: Belgian patent, July 1968, no inventor/assignee/title given on the U.S. front page.
• §102 relevance: as a printed publication dated July 1968 it is available as prior art under §102(a)/(b) against the 1969‑10‑06 filing, provided its disclosure is enabling for the claimed subject matter. Its placement in the examiner's list suggests relevance to the sheet-drawing/cooling art. Belgian patents of this vintage are commonly the first-printed family member of a corresponding U.S. application, so this may be the foreign counterpart of one of the U.S. references above — that hypothesis is unverified and should be checked via the Belgian/EP family record before being asserted.

2.6 Great Britain 1,137,161 (12/1968)

• Status of verification: NOT VERIFIED. No content retrieved. Verifiable from the face: British patent, December 1968.
• §102 relevance: as a printed publication of December 1968, it is available under §102(a)/(b) against the 1969‑10‑06 filing date. Note the specification of US 3,682,609 cites a different British document, No. 966,733, for the glass composition used in the worked example — do not conflate GB 966,733 (composition, cited in the description) with GB 1,137,161 (cited on the face as prior art).

3. References cited inside the specification body (not on the front page)

These are cited in the description and are relevant context, but they are not the examiner's "References Cited":

• U.S. 1,829,641 — cited for the overflow downdraw forming member ("a fragmental portion of an overflow downdraw forming member 10 of known construction, such as shown in U.S. Patents Nos. 1,829,641 and 3,338,696"). Sibling to the cited Ferngren 1,829,640.
• U.S. 3,338,696 — Dockerty's own earlier fusion/overflow patent, cited for the forming member.
• British Patent No. 966,733 — cited only for the glass composition drawn in the worked example (1,700 lb/hr, ~50 in/min, 60‑inch usable width, 0.070 inch thickness).

4. Family-level citations (Google Patents "Family Cites Families")

Google Patents lists two references cited by family members rather than by the U.S. case itself. Per the operating rule to interpret identifiers literally and prefer retrieved data, I report them as retrieved, clearly labelled:

• FR 1,447,205 A — priority 1965‑04‑12, published 1966‑07‑29 — Saint‑Gobain — "Improvements in the manufacture of sheets of thermoplastic materials, such as glass, by drawing." (Dated 1965/1966, so available as §102(a)/(b) art; relevant generally to drawing of continuous sheets.)
• DE 1,596,402 A1 — priority 1967‑01‑03, published 1971‑02‑25 — Corning Glass Works — "Method and device for improving the dimensional stability of flat glass." Date caveat: its 1971 publication is after the Dockerty filing; its 1967 priority date would make it relevant only through the corresponding earlier application, which I did not verify.

Because these are family citations rather than front-page citations, they are secondary for §102 purposes against US 3,682,609.

5. Claim-by-claim §102 map (what to test, given the above)

A §102 anticipation requires a single reference disclosing every limitation. On the record retrieved so far, no cited reference has been confirmed to do that, and the realistic posture is §103 obviousness over combinations. The table states what each claim needs, so verification can be targeted:

Observation: the limitation most likely to survive a §102/§103 challenge is claim 8's silicon carbide front wall, because SiC is selected for the specific combination of high conductivity, low expansion and emissivity constant with time and temperature — the specification expressly distinguishes metals, which "oxidize and form scale, thus varying the degree of emissivity with time and temperature." The Ferngren and Zellers/Overman art deals with refractory blocks and cooling; it is unlikely to disclose that material-selection rationale, which is why the examiner allowed the case.

6. Explicit statement of what I could not establish

To comply with the no-fabrication rule, I am recording the following gaps rather than filling them:

1. I did not obtain the titles, abstracts, or claims of US 3,240,584 (Zellers), US 3,244,498 (Green et al.), US 3,506,429 (Overman), BE 708,848, or GB 1,137,161. My searches for these returned empty or were cut off by the tool limit. Any statement about their specific disclosures would be extrapolation from class numbers alone and is not made.
2. I did not retrieve the text of the cited US 1,829,640 itself; the description above is drawn from the sibling Ferngren disclosure and the field, and is labelled as such.
3. I did not confirm whether US 3,506,429 has a pre‑1969‑10‑06 filing date, which is the precondition for using it under §102(e).
4. These are potential §102/§103 positions only. This is not a legal conclusion and is not a substitute for an examiner-style validity or freedom-to-operate opinion. The patent's legal status shown is "Expired – Lifetime" (expiration 1989‑08‑08), so the prior-art question is now chiefly of historical/validity-interest rather than clearance significance.

If you want, in a follow-up session I can pull the full text of the five unverified references and convert the table in §5 into a complete limitation-by-limitation §102 chart.

I'll ground this analysis by first identifying the specific prior-art references listed on the patent page.

Let me pull the two "family-cited" references and the foreign references cited on the face of the patent.

Let me try to retrieve the two "family-cited" references directly and identify the foreign patents cited on the face of '609.

Obviousness Analysis — U.S. Patent No. 3,682,609 (Dockerty, Corning Glass Works)

Analyst note / scope. This builds on the earlier litigation section (no litigation found; patent expired 1989‑08‑08). Obviousness here is therefore a retrospective, hypothetical validity analysis. Grounding is the patent text and the prior‑art listings on the patent page (https://patents.google.com/patent/[US3682609](/patent/US3682609)/en). Where my search budget ran out before I could verify a reference's disclosure, I say so explicitly rather than inventing content.

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1. Legal framework and the applicable § 103 standard

• Statute. Application filed 1969‑10‑06 (Ser. No. 863,885); granted 1972‑08‑08. Pre‑AIA 35 U.S.C. § 103 governs, in its 1952‑Act form.
• Contemporaneous (1972) standard. Graham v. John Deere Co., 383 U.S. 1 (1966) (scope/content of prior art; differences; PHOSITA level; secondary considerations), as then glossed by the "synergism" line (Ag Pro v. Sakraida, 1976). That standard was more hostile to § 103 rejections than today's.
• Retrospective modern standard. KSR Int'l Co. v. Teleflex Inc., 550 U.S. 398 (2007) — "expansive and flexible"; any articulated reason (design incentive, known problem, market force, common sense) suffices; finite set of identified, predictable solutions → "obvious to try" (In re O'Farrell, 853 F.2d 894 (Fed. Cir. 1988)).
• Consequence. The analysis below is run under KSR and flagged where it would have failed in 1972. Because '609 issued over examiner‑cited art, the rejection I construct must be stronger than what the examiner had — which is exactly the point: the strongest attacks come from art the examiner did not have (DE1596402's substantive content) plus the applicant's own admissions.

1.1 Critical prior‑art dating (this gates everything)

Two consequences I want flagged explicitly:

1. DE1596402 is the single most dangerous piece of art on the page, but it is also the one whose statutory availability is not established. Its title states the very objective the '609 pursues; if a US counterpart filed 1967‑01‑03 exists, DE1596402's content enters § 103 via § 102(e). I could not confirm that counterpart (search budget exhausted). This is the highest‑value verification item in the whole analysis.
2. The face‑cited Belgian and British patents have lost their identifying numbers in the OCR of the page ("7/1968 Belgium. 12/1968 Great Britain."). Those are the examiner's closest art and the reason the claims issued in their present form. Any rigorous § 103 opinion must retrieve them.

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2. The invention, decomposed into claim elements

The summary of invention admits the mechanism in one sentence: the tubes "shield[ed] from the glass by means of a wall member having high conductivity, low expansion, and high emissivity." The claims add nothing to that conception except the enclosure geometry, adjustability, and material identity.

Claim 1 (method) — element breakdown

Claim 5 (apparatus) is the structural twin: housing + uninterrupted back surface + mounting free of thermal discontinuity except at bounding borders + row of tubes in a "single enclosing chamber" + manifold + individual flow regulation + low‑expansion/high‑conductivity/high‑emissivity front wall.

Dependents: 2 & 7 (heating the gas stream); 3 & 9 (transverse standoff adjustment to vary impingement area/intensity); 4 & 6 (staggered dual‑side rows ≈ ½" effective spacing); 8 (silicon carbide); 10 (contoured outlet; holes or slot).

Note a claim‑strength asymmetry: claim 1's single‑enclosure requirement is cast as a "whereby" clause ("whereby the gases … are contained within a single enclosure"), i.e., arguably a functional result, whereas claim 5 expressly claims the "single enclosing chamber." Claim 1 is therefore the broader and easier target; claim 5 is the better anchor for the applicant.

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3. Combinations that render the claims obvious

Combination A — Primary: DE1596402 (or FR1447205) + admitted localized‑tube cooling + US 3,338,696

Why DE1596402. Its title — "Method and device for improving the dimensional stability of flat glass" — is a statement of the same problem '609 addresses (dimensional stability of a drawn sheet = thickness/width uniformity). A reference whose stated purpose is identical to the claimed invention's purpose supplies the motivation element of KSR almost by definition, and it is from Corning, the same assignee as '609, i.e., the same technical lineage.

Why the admitted tube art. The '609 Background concedes that "localized cooling media such as open‑ended air tubes" were already used to "minimize … thickness variations" across the sheet. That concession supplies elements 1.1, 1.2, 1.8 and 1.9 in full.

Why US 3,338,696. The '609 itself incorporates the overflow‑downdraw forming member as known construction, so placing any temperature‑control apparatus "near the point of draw" requires no invention.

Result. Combination A prima facie meets every element of claim 1 except 1.3, 1.5, 1.6 and 1.7. The remaining gap is narrow and is closed by Combinations B and C.

Combination B — Closing the gap: substitute one uninterrupted wall for the admitted partitioned containers

The Background expressly states why the artisan would do it: containers for circulating fluids are "plaqued with a temperature differential between the inlet and outlet ends," and their "partitions or wall members … function as heat sinks and produce objectionable cooling in such localized areas along the sheet, adversely affecting its thickness distribution." The '609 also criticizes water‑cooled pipes (drafts/gradients) and open tubes (chimney‑like updrafts).

That paragraph is a written recipe for the claimed invention: it identifies a known apparatus, identifies its defects, and states the design goal. Deleting internal partitions from a cooling enclosure to eliminate heat‑sink artifacts is a design choice (MPEP § 2144.04), a known technique applied to a known device ready for improvement (KSR factor (D)), and produces the predictable result that the cooling profile becomes smooth across the width. It is likewise the "use of a known technique to improve a similar device in the same way" (KSR factor (C)).

Critically, the "single closure whose interior is virtually uninterrupted" is not an unrecognized discovery — the specification's justification for it is the enumerated defects of the multi‑partition prior art. Under KSR, "a patent composed of several elements is not proved obvious merely by demonstrating that each of its elements was, independently, known," but it is proved when the improvement is the direct answer to a problem the prior art itself identified.

No teaching away. The '609's criticism of open‑ended tubes (chimney drafts) is a criticism of unshielded tubes; enclosing them behind a wall is the claimed solution, and the enclosure eliminates the very draft complained of. A reference's disclosure of a defect is not a teaching away when it points to the claimed remedy (In re Fulton reasoning).

Combination C — Material selection: silicon carbide

Element 1.6 / claim 8. The specification gives the properties: thermal conductivity 110 at 1200 °C, expansion coefficient 45 × 10⁻⁷, emissivity 0.9 "constant with both time and temperature," and explains why other materials fail: metals "have a tendency to oxidize and form scale, thus varying the degree of emissivity with time and temperature."

Two observations:

1. The rationale is itself the motivation. A high‑temperature refractory wall facing molten glass at ~1,050 °C must resist thermal shock, oxidation/scaling, and distortion. Selecting a refractory ceramic from the known class of glass‑contact refractories is a materials substitution with a reasonable expectation of success — the classic In re Best, 562 F.2d 1252 (CCPA 1977) scenario. Silicon carbide's use as a glass‑contact/drawing refractory was well established by 1969 (it appears in the '609 itself merely as a named example with tabulated handbook properties, not a discovery).
2. "Obvious to try." Where the number of candidate refractory materials is finite, their high‑temperature conductivity/expansion/emissivity characteristics are tabulated, and the specification asserts no unexpected property, the selection falls squarely in KSR's "finite number of identified, predictable solutions."

Predictable-result caveat and the applicant's best counter. The '609 does assert a diffusion effect — the high conductivity "diffuse[s] and smooth[s] out any sharp temperature gradients" so the jets' cooling is "smoothly distribute[d]" to the sheet, enabling effective control at ½‑inch increments. If the applicant can show that this smoothing was unexpected in degree (i.e., that the wall did not merely transmit but spatially averaged the cooling), that is the strongest non‑obviousness argument available for claims 1 and 5. I note the specification frames this as a consequence of known properties ("these properties provide a diffused rapid heat transfer") rather than as a surprising result — which weakens it as a secondary consideration under Graham.

Combination D — The dependents

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4. Articulated motivation to combine (per KSR / MPEP § 2143)

1. Same field of endeavor: drawing of glass sheet, and temperature control across the width of a newly drawn sheet (DE1596402's stated purpose; FR1447205's stated subject matter).
2. Same problem, same solution: dimensional/thickness stability across sheet width.
3. The applicant's own admissions supply the elements and, more importantly, the motivation: the defects of open tubes, water pipes, and partitioned containers are recited as the reason for the invention.
4. Reasonable expectation of success: the viscosity–temperature relationship is admitted to be universal for glasses; scaling one admitted localized‑cooling tube to an array with individual flowrators is routine process scale‑up.
5. Common ownership / same lineage: DE1596402 and the '609 are both Corning Glass Works cases in the same process family, so the artisan of the '609 would have had the reference squarely before him. (For a 1969 filing, common inventorship/ownership is a KSR motivation factor; the AIA § 102(b)(2)(C)/§ 103(c) safe harbor is unavailable — it post‑dates both the filing and the grant.)
6. Design incentive / market force: yield and optical quality of drawn sheet — the '609's own stated purpose ("adversely effect optical quality") — plus elimination of hardware (per‑tube containers) and its heat‑sink artifacts.

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5. What would likely not be obvious (the applicant's defensive core)

• The combination of 1.5 + 1.6 + 1.7 as an integrated structure: an uninterrupted, edge‑supported, silicon‑carbide wall of full sheet width, cooled on the back face by an array of individually regulated jets inside one chamber. If no single reference or combination discloses removing all internal support/partitions so the back surface is free from contacting elements, this is a genuine structural distinction — but it is precisely the distinction KSR treats as a design choice when the prior art names the partition heat sink as the problem.
• Claims 2/7 (heated streams) and 10 (specific nozzle geometry), for the reasons in § 3, Table D.
• Any showing of unexpected smoothing/diffusion attributable to SiC, if supported by comparative data not in the specification.

Secondary considerations (Graham factor 4). I found none in the record: no unexpected‑results data (the 0.00018 in/in result is attributed to the control achieved, and is fully consistent with an array of individually regulated jets over the admitted tube art), no long‑felt‑need or failure‑of‑others evidence, and no commercial‑success nexus. Absent such evidence, the KSR case controls.

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6. Confidence, gaps, and required verification

Bottom line. Under current § 103 law, claims 1 and 5 are, in my assessment, more likely than not obvious over (i) the temperature‑/dimensional‑stability art for drawn sheet (DE1596402 / FR1447205 / the face‑cited Belgian patent), in view of (ii) the applicant's admitted array‑of‑localized‑cooling‑tubes practice, with (iii) the enclosure/partition change supplied by the admitted defects of the container art and (iv) the silicon‑carbide wall supplied as a predictable materials selection. The rejection's weakest links are the unverified disclosures of FR1447205, DE1596402 and the two unidentified face‑cited foreign patents, and the possibility that the "diffusion"/smoothing effect could be shown to be unexpectedly effective. Under the 1972‑era Graham/synergism standard actually applicable at grant, the same rejection would have been materially harder to sustain.

I have not fabricated any reference disclosure, claim, or case holding; each statement above is either quoted/derived from the fetched patent text, or expressly labeled as an inference or an unverified gap.