US 4085284

I'll run the requested database searches before summarizing.

Searches performed

• USPTO/Google Patents full-text for 4085284 — matched US4085284A, "D-shield telephone cables" (https://patents.google.com/patent/[US4085284](/patent/US4085284)/en)
• CAFC 2026 dockets for 4085284 — no results tying this patent number to any Federal Circuit appeal or 2026 docket. The only CAFC 2026 material returned concerned unrelated patents (e.g., U.S. 10,894,503 in Spero v. Mercedes-Benz USA, No. 2025-1470). I found no litigation, IPR, or appeal activity for 4085284. Treat that as "no evidence found," not proof of absence.

Bibliographic data for US 4,085,284

Discrepancy note (not auto-corrected): the two sources disagree by one day on priority/grant/expiration dates. The Google Patents record (which supplies the authoritative text above) gives 1976-08-10 filing and 1978-04-18 publication; I am reporting both rather than harmonizing them.

Abstract (verbatim)

"This internally shielded telephone cable provides more efficient shielding for meeting near-end crosstalk requirements in carrier systems having expanded channel capacity and increase in equivalent frequency from 772 kHz to 1.576 MHz or higher. The improved shielding uses tapes bent into configurations that obtain greater shielding area from a single tape, and constructions that are less expensive than prior art and produce a mechanically stronger and more unitary cable structure."

The patent is expressly an improvement on U.S. 3,803,340 (issued 1974-04-09), the original "D" internal shield design.

Independent claims in plain language

There are three independent claims: 1, 16, and 17. (Claims 2–15 depend, directly or indirectly, on claim 1.)

Claim 1 — the cable (product). A communication cable with two cable cores, each carrying messages in a different direction. Each core is a bundle of insulated conductors held together by a core wrap. Each core has its own metal shield around it, with the core wrap sandwiched between the shield's inner surface and the conductors (so the shield never touches conductors). The key limitation: each shield surrounds its own core and has an area that confronts and contacts a part of the other core's shield, and that confronting contact is bonded — this bond is what makes the two halves one unitary structure.

Claim 16 — the cable (product), broader/structural phrasing. A communication cable with two segmental cores (i.e., half-round cores), each carrying messages in a different direction, each bound by a core wrap and enclosed by a one-piece metal shield that (a) provides lightning protection for the conductors and (b) also extends between the cores to isolate the two transmission directions from one another. Part of the shield around one core is bonded to part of the shield around the other core. Note that the shield here is described as one-piece, and the claim ties the shield to both crosstalk isolation and lightning protection functions.

Claim 17 — the method. A method of making such a cable: (1) wrap each core with a plastic core wrap to hold the conductors together; (2) longitudinally fold a metal shielding tape around each core, outside the plastic wrap; (3) shape the shielding so that areas of the shielding for one core confront areas of the shielding for the other core; and (4) bond those confronting areas to each other so the shielding becomes a unitary structure.

Notable dependent claims (context for the independent claims)

• Claim 3: shields are aluminum with a corrosion-protecting coating, bonded by a fusion bond between the coatings.
• Claim 4: shields are longitudinally folded metal tapes with seams located along a circumferentially extending portion of the shield.
• Claim 5: aluminum up to 8 mils thick, lap seam.
• Claim 9: the shielding is a single tape folded so each circumferential part wraps its core and overlaps past where the other part merges with the radial portion; each overlap is bonded.
• Claim 10: an additional laminate over the common (diametral) shielding portion to increase its thickness.
• Claim 12: both shields have radially extending parts that confront one another, giving double-thickness shielding between the cores, in contact.
• Claim 14: each shield is a longitudinally folded aluminum tape up to ~8 mils.
• Claim 15: shielding is transversely corrugated to increase cable flexibility (see FIG. 6).

Specification highlights relevant to the claims

• The commercial driver was the 48-channel PCM carrier system (T1-C), which raised equivalent frequency from 772 kHz to 1.576 MHz and pushed near-end crosstalk requirements to a tentative 80 dB worst-case power sum; the earlier design of U.S. 3,803,340 was found marginal, especially in small pair-count cables.
• The bond between confronting diametral shield faces is emphasized both for mechanical strength ("unibody construction") and for eliminating a possible water channel between the shields.
• Claims of cost efficiency rest on using a wider tape whose total width exceeds the cable core circumference, allowing thinner tape while matching the cross-section of a standard 8 mil circumferential shield (a stated industry requirement).
• FIGS. 3 and 4 are identified as the preferred embodiments; FIG. 5 shows the corrosion-protecting coating on both faces of the aluminum; FIG. 6 shows the corrugated shield with inner lobes against the core wrap and outer surface against the extruded jacket.

Certainty and limitations

• Title, inventors, assignees, abstract, claim text, and dates above are grounded in the full patent record you supplied plus the Google Patents/Justia/Unified listings; those are reliable.
• I could not confirm any CAFC 2026 docket, IPR, or district-court litigation involving 4085284 from search results. The absence of results is not authoritative proof of no litigation.
• The one-day date discrepancies (priority 1976-08-09 vs. 1976-08-10; grant 1978-04-17 vs. 1978-04-18) come from differing databases and are reported literally rather than resolved.
• I did not independently retrieve the PDF images, so figure descriptions rely on the specification text.

I'll search for litigation involving US patent 4085284 across patent litigation databases.

Let me check the litigation databases directly.

Let me try litigation-specific sources including CourtListener and the Unified Patents litigation portal.

Answer: No litigation found involving U.S. Patent No. 4,085,284

Based on the searches I was able to run against patent-litigation sources (Unified Patents patent portal, Google Patents family/litigation data, general web/CourtListener-indexed results), I found no record of any lawsuit — district court, ITC, or Federal Circuit — in which U.S. Patent No. 4,085,284 was asserted, challenged, or otherwise at issue.

What I searched

Specifically not this patent (avoiding false positives)

Several records with a "284" string populated the results but are different patents or different subject matter and should not be confused with U.S. 4,085,284:

• U.S. 10,038,284 B2 — coaxial connector patent at issue in IPR2022-00720 (PTAB). Different patent.
• Hoover Group, Inc. v. Custom Metalcraft, Inc.*, 84 F.3d 1408 (Fed. Cir. 1996) — refers to "the '284 patent," but that is a Hoover patent on tank/container technology, not U.S. 4,085,284.
• U.S. 6,932,124 (Ice House America v. Innovative Packaging Technologies) — unrelated.
• A Bolivian/Argentine official gazette entry listing "N° 4085284/17" — an administrative domain-registration number, not a patent.

Context and caveats

• Patent term: U.S. 4,085,284 issued April 18, 1978 (filed Aug. 10, 1976) and, as a pre-URAA patent, ran 17 years from grant — expiring April 18, 1995 (Google Patents legal-status: "Expired – Lifetime"). Any enforcement litigation would necessarily predate mid-1995.
• Assignee chain: General Cable Corp. → GK Technologies, Inc. → General Cable Industries, Inc. A party with standing to sue would have been General Cable or its successors — I found no suit by or against them on this patent.
• Data-coverage limitation: The lack of results is partly a function of record availability. CourtListener/RECAP and the Unified Patents litigation caselist are heavily weighted toward post-1990s electronic filings. A 1978–1995 case could exist yet not appear in these databases. Because I was unable to complete additional targeted docket searches before running out of queries, I cannot state with absolute certainty that no suit was ever filed — only that no litigation is documented in the sources searched.

Bottom line

No known litigation involving U.S. Patent No. 4,085,284. This is consistent with the patent's age and expiration (1995); there are no patent cases matching this number in the litigation databases searched. If you need a definitive check for the 1978–1995 window, the next step would be a manual PACER docket search restricted to that date range and to the likely plaintiffs (General Cable Corp./GK Technologies) — those older dockets are generally not indexed by the free litigation portals.

I'll check the structured data first and then verify with targeted searches.

PTAB / AIA Trial Activity on US 4,085,284 — "D-shield telephone cables"

Proceedings overview

Zero AIA trial proceedings on file. Per the structured "PTAB proceedings on file" block sourced from the USPTO Open Data Portal (most recent ingest), there are no IPRs, no PGRs, and no CBMs involving US 4,085,284 — count: 0 total; 0 active, 0 claims invalidated, 0 claims sustained, 0 settled, 0 institution denials. I ran independent web searches to catch anything the ODP ingest missed and found no PTAB proceeding, no Federal Circuit appeal, and no district court assertion of this patent. The bottom-line defensive posture is not the usual "the patent has survived and is hardened" — it is stronger and simpler than that: all 17 claims are expired and unenforceable, so the patent cannot be asserted against your client at all. The absence of PTAB activity here is fully explained by expiration, not by the patent's litigation strength.

Verification note / confidence level. I searched for IPR/PGR/CBM numbers tied to "4085284," the inventors (Olszewski, Jachimowicz), and the assignee (General Cable), and reviewed Unified Patents' patent page, which tracks PTAB and litigation activity (including defensive-aggregator filings). Nothing surfaced. I could not query PTAB E2E or the PTAB Decisions database directly through my tools, so the "no proceedings" finding rests on (a) the ODP structured data, which is canonical here, and (b) the absence of any web hit. I found no evidence of a proceeding; I did not find a proceeding I am withholding.

No proceeding to report — but here are the four facts that govern this patent

Since there is no {PROCEEDING_NUMBER} to headline, the material for a defendant is the status of the patent itself and the reason it has never been challenged at the Board.

Why no IPR exists — and why that is not a strength signal. The AIA trial regime did not exist until 2012-09-16. This patent expired roughly 17 years earlier (1995). An expired patent cannot be infringed, so there is no accused product, no case-or-controversy pressure, and no economic reason for a petitioner to spend the filing fees: even a total win at the Board would cancel claims that already carry no exclusionary right. The normal heuristic — "a well-asserted patent eventually attracts an IPR" — is inapplicable; the correct inference from zero proceedings is "the patent aged out of relevance before the AIA existed," not "the patent withstood attack."

What the claims look like today (all UNTESTED)

Because no tribunal has ever construed or invalidated any claim, the correct classification is a single bucket:

• CANCELED: none. No claim of US 4,085,284 has been canceled, disclaimed, or held invalid in any proceeding I could locate.
• SUSTAINED: none. No claim has been upheld by the PTAB or a court — there is nothing to cite for validity.
• UNTESTED: claims 1–17, all of them — but all expired and therefore unenforceable. Claim 1 (the independent cable claim), claim 16 (the independent "segmental cable cores" claim), and claim 17 (the independent method claim) are the only independents; claims 2–15 depend from claim 1, and claim 15 recites transverse corrugation for flexibility. See the full claim set.

Two caveats worth putting in a memo:

1. No reissue of this patent. The face of the record shows a related reissue US RE31,277 E (1983-06-14) and US 4,165,442 (1979-08-21), both to General Cable and both stemming from the same 1978-06-12 filing — i.e., follow-on family members, themselves long expired. Do not conflate those with 4,085,284; a demand letter citing "the '284 patent family" needs to specify which number, and all of them are dead.
2. Expiration is the complete defense. The Google Patents legal-status entry reads "Expired - Lifetime" with anticipated expiration 1995-04-18, and the ODP-derived status for the priority application is likewise "Expired." There is no scenario in which a 1978-granted patent whose term ran out in 1995 supports an infringement claim in 2026.

Strategic summary

Claim status. All 17 claims of US 4,085,284 are expired and unenforceable, and — independently — untested at the PTAB. There are no surviving claims to design around and no canceled claims to check a demand letter against. If a patent owner or NPE has sent your client a letter citing this number, the response is not an invalidity argument; it is a term-and-enforceability argument: the patent's protection ended in April 1995, more than three decades ago, and the assignee chain (General Cable Corp. → GK Technologies, Inc. → General Cable Industries, Inc., recorded 1994-02-24) confirms nobody ever revived it.

Estoppel landscape. § 315(e)(2) estoppel is irrelevant here — there is no petitioner and no instituted trial, so no party is barred. Conversely, there is no IPR estoppel benefit to claim either: a defendant gets nothing from the Board's work because the Board never did any. Any invalidity theory must be built from scratch in district court, and even that is academic given expiration.

Pattern signals. No repeat petitioner, no serial filings, no defensive aggregator involvement (Unified Patents' page shows only the reference list — "Patent Art (8)," "Non-Patent Literature (0)," "Referenced By (44)" — and no trial or litigation tab content), and no PTAB appeal activity. There is no NPE in the chain; the patent has sat with General Cable/Prysmian-affiliated entities and their predecessors since 1976. The only litigation texture in the neighborhood is unrelated — e.g., General Cable's 2006–2010s US 5,767,441 dispute with Nexans concerning paired data cables, which has nothing to do with 4,085,284 and involved a district court claim-construction opinion, not the PTAB.

Where this patent actually bites. US 4,085,284 is a 1976-priority printed publication, and that is its only live significance. It is cited as prior art in later prosecution — for example, as an "A" category reference in EP 0 169 987 A1 ("Communications cables," published 1986-02-05, EPO Global Patent Index) — and it appears in the "Cited By" lists of 44 later documents, including Belden's and General Cable's own family members. If your client is asserting a different, later cable patent in the D-shield / internal-shield space, the productive use of 4,085,284 is as § 102 prior art against that later patent's claims, not as an invalidity target itself. It also forms the admitted-prior-art backdrop of its own family: the specification expressly states the invention "is an improvement on the construction disclosed in U.S. Pat. No. 3,803,340," so the '340 patent and the eight references on the '284 face (including GB 492,333; US 3,622,683; CA 953,384; and US 3,968,321) are the natural starting set for any art-based attack on a successor patent.

Recommended next steps

1. If you have received a demand citing US 4,085,284 — test the premise, then answer flatly.
Do not pay, and do not respond on the merits. The patent expired on 1995-04-18 and the ODP status reads "Expired - Lifetime" (source). There is no Board decision to link because none exists. Assertion of an expired patent is meritless, and a letter citing claims 1–17 of this patent is, at minimum, a Rule 11 / § 285 exposure problem for the sender. Recommend a short, dated response from counsel citing the expiration date and asking the sender to withdraw.

2. If the demand cites a later patent in the same family or field — pivot to prior art.
Pull 4,085,284 and its cited references, run them against the asserted claims, and note that the specification's own admission of US 3,803,340 as prior art narrows the available scope. This is where the patent's 1976 priority date has value for you.

3. No IPR is available to you, and no IPR clock is running.
There is no pending proceeding, so there is no § 316(a)(11) one-year deadline, no institution decision date, no oral hearing, and no FWD due date to track. Filing an IPR against an expired, unenforceable patent would be a waste of fees (the Board has in some circumstances permitted review of expired patents, but the practical value is nil when no exclusionary right remains). If you need a formal cancellation of the record, note that reexamination of an expired patent is technically available on patents-and-printed-publications grounds, but it too is almost certainly moot — advise the client accordingly rather than spending on it.

4. Document the absence.
Keep a short file memo recording that as of 2026-10-01 the USPTO Open Data Portal returns no AIA trial proceedings for US 4,085,284 and that independent searching (Google Patents, Unified Patents' tracking portal, general web) surfaced none. If opposing counsel or an NPE implies the patent has been "tested" or is "in force," that memo is your rebuttal.

I'll start by pulling the assignment records and cross-referencing sources.

The main assignment reels are surfaced in the Google Patents legal events. Let me try to pin down the correspondent and confirm via USPTO sources.

⚠️ Data-access limitation up front: I could not open a full USPTO Assignment Center "Abstract of Title" for 4,085,284 — the session's remaining tool budget was exhausted before I could retrieve the recorded correspondent fields. The reel/frame numbers and conveyance types below come from the Google Patents Legal Events block in the authoritative record you supplied (which mirrors the USPTO assignment data), not from a direct Assignment Center abstract. I have not fabricated any correspondent name or missing reel/frame. Where a field was not retrievable, I say so.

Inventors

Pattern check — departures within 12 months of filing: Not determinable. I found no evidence either way on whether Olszewski or Jachimowicz left General Cable in 1976–77. I did not find a record of an inventor→General Cable Corporation assignment in the Google Patents legal-events list for this patent (which shows only two 1994-recorded entries). That is a gap in the surfaced record, not proof that none exists — initial inventor assignments are frequently recorded but omitted from third-party legal-event feeds. I am not asserting an anomaly here.

Original assignee

General Cable Corporation (originally incorporated in New Jersey, 1927; world headquarters later at 4 Tesseneer Drive, Highland Heights, Kentucky).

• Primary line of business: manufacturer of copper, aluminum and fiber-optic wire and cable for energy, industrial, construction, specialty and communications markets. A genuine operating manufacturer — not a holding company.
• Product embodying the claims: Yes, on the record. The specification is written as a commercial cable design ("D-shield telephone cables") built to meet the 48-channel PCM (T1-C) near-end crosstalk requirement of 80 dB worst-case power sum at 1.576 MHz, with an explicit cost-competitiveness discussion against the "two separate cable approach." That is production-engineering language, not licensing language. General Cable was a large, publicly traded cable manufacturer during the relevant period.
• Current status: The original named assignee no longer exists under that name. Corporate history (FundingUniverse company history; General Cable 10-K; Sunbiz name-change record):
  • 1979 — General Cable Corporation changed its name to GK Technologies, Incorporated (this matches the reel cited below).
  • 1981 — Penn Central Corporation (later American Premier Underwriters, Inc.) acquired GK Technologies.
  • 1994 — A subsidiary of Wassall PLC acquired the General Cable predecessor; General Cable later traded on NYSE as BGC.
  • 2018-06-06 — General Cable became a wholly-owned subsidiary of Prysmian Group (Italy). Today the General Cable brand operates inside Prysmian.
  • The patent itself expired 1995-04-18 (17 years from the 1978-04-18 grant), so it has been in the public domain for three decades.

Assignment timeline

Two post-issuance records are surfaced. Both were recorded on the same day, 1994-02-24, long after their effective dates — a classic housekeeping catch-up recording.

1979-04-25 (effective) / recorded 1994-02-24 — Reel 006867/0768

• Conveyance: Change of Name
• Assignor: General Cable Corporation
• Assignee: GK Technologies, Incorporated (Kentucky)
• Correspondent: Not retrieved. I could not pull the Assignment Center abstract; no correspondent name will be asserted here.
• Context: Change of name only — an internal corporate identity change, no transfer of ownership and no change in beneficial owner.

1993-04-23 (effective) / recorded 1994-02-24 — Reel 006875/0429

• Conveyance: Assignment of Assignors' Interest (per the recorded Google Patents description: "ASSIGNMENT OF ASSIGNORS INTEREST")
• Assignor: GK Technologies, Incorporated
• Assignee: General Cable Industries, Inc. (Kentucky)
• Correspondent: Not retrieved (same limitation as above).
• Context: Internal reorganization / transfer of the cable business into a successor entity, contemporaneous with the 1994 Wassall PLC acquisition of the General Cable business from American Premier Underwriters. This is not a sale to a third-party licensing entity — the transferee is a cable-manufacturing operating company that Google Patents lists as the current assignee.

Not found / not retrieved:

• No inventor→General Cable Corporation assignment appears in the surfaced legal-events list (see caveat above).
• No security agreement, license, release, merger, or corrective assignment for this patent was surfaced.
• No assignment to any LLC, "IP Holdings," "Licensing," "Ventures," or similar entity was surfaced.

Timeline diagram

timeline
    title Ownership of US 4085284
    1976 : Filed by General Cable Corp
    1978 : Patent issued
    1979 : Name change to GK Technologies
    1993 : Assigned to General Cable Industries Inc
    1994 : Both records filed at USPTO
    1995 : Patent expires
    2018 : General Cable acquired by Prysmian

Note on parseability: I deliberately omitted the assigned-patent title and any commas/parentheses from event text. The 1993 transfer is shown on its effective date; the USPTO recording of both links occurred 1994-02-24.

NPE / troll-pattern signals

1. Shell-entity transfer — not present. The only post-issuance assignee is General Cable Industries, Inc. (reel 006875/0429), a Kentucky cable-manufacturing entity, not a licensing vehicle. No "IP/Holdings/Ventures/Licensing" suffix appears anywhere in the surfaced chain, and no single-purpose DE or TX LLC is involved.

2. Known asserter in the chain — not present. Neither GK Technologies, Incorporated (reel 006867/0768) nor General Cable Industries, Inc. (reel 006875/0429) appears on the Acacia / Marathon / Intellectual Ventures / IPNav / Wi-LAN / Mosaid-Conversant / Vringo / Pendrell / Round Rock / Lumen View lists, and neither appears in Unified Patents' or RPX's high-frequency-plaintiff directories in the material I retrieved. The current assignee is a Prysmian Group subsidiary.

3. Repeat correspondent across the chain — unclear. This is the one signal I cannot clear. The correspondent of record is exactly the field that would reveal a repeat-player attorney, and I failed to retrieve it for either reel (006867/0768 and 006875/0429). I will not name a correspondent I did not see. To close this out, pull the two Supporting Assignment PDFs for those reels from Assignment Center.

4. Cascading transfers — not present. There are two links, effective 1979-04-25 and 1993-04-23 — roughly 14 years apart. Although both were recorded on the same day (1994-02-24), that simultaneity reflects a single housekeeping event, not a chain of LLCs recycled within 24 months. No shared-correspondent LLC cascade exists.

5. Pre-litigation transfer — not present (no predicate). The prior litigation analysis found no infringement suit asserting 4,085,284 in any searched source. With no suit, there is no 6-month pre-litigation window to test. The nearest transfers predate any conceivable suit by years and the patent expired in 1995.

6. Bankruptcy fire-sale — not present. No Chapter 7/11 proceeding involving this patent was found. General Cable's later financial distress (FCPA settlements, 2015–2017 investor suits) and its 2018 acquisition by Prysmian are not bankruptcy sales, and post-date the patent's 1995 expiration in any event.

7. Privateering — not present. No evidence that an operating company transferred this patent to an NPE for assertion against competitors. The chain runs operating company → operating company.

8. Defensive aggregator (anti-NPE) — not present. No RPX, AST, LOT Network, Unified Patents, or OIN entity appears in the chain. (The patent was not "neutralized" by a defensive aggregator; it simply expired.)

Verdict

Insufficient data.

The ownership record surfaced for US 4,085,284 consists of one change-of-name (reel 006867/0768, effective 1979-04-25, General Cable Corp → GK Technologies, Incorporated) and one intra-group assignment (reel 006875/0429, effective 1993-04-23, GK Technologies, Incorporated → General Cable Industries, Inc.), both recorded 1994-02-24 as part of the divestiture of the General Cable business from Penn Central/American Premier Underwriters. That is a pure operating-company chain with zero NPE indicators — no shell entity, no known asserter, no cascade, no fire-sale, no privateering, no defensive aggregator, and no litigation — but because there is no assertion event to classify and the correspondent fields were not retrievable, I cannot responsibly place this in a positive category. I flag explicitly that "Insufficient data" here reflects a data gap (correspondent of record unrecovered) and the absence of any assertion, not a suspicion of NPE activity; on the evidence, an NPE hypothesis is affirmatively unsupported.

Verify at: https://assignment.uspto.gov/patent/index.html — search patent number 4085284, then open the supporting assignment PDFs for reels 006867/0768 and 006875/0429 to capture the corresponding attorney/firm and confirm whether any additional records (e.g., the original inventor assignment) exist beyond the two entries surfaced here.

Contradiction flag: nothing in this section contradicts the previously generated sections. The one-day date discordances (priority 1976-08-09 vs. 1976-08-10; grant 1978-04-17 vs. 1978-04-18) flagged earlier remain unresolved and are reported literally, not harmonized.

I'll research each cited reference before mapping them to the claims.

Now let me research the remaining cited references.

Prior-Art Analysis — U.S. Patent No. 4,085,284 ("D-shield telephone cables")

0. Record confirmation

The USPTO/Google Patents record returned for 4085284 is US 4,085,284 A, application US 05/713,228, "D-shield telephone cables," Olszewski & Jachimowicz, General Cable Corp. No other, similar patent numbers are relied on below. (This matches the bibliographic section already produced; repeated here only as the anchor for the prior-art table.)

The "Citations (8)" set in that record is the controlling prior-art list. The forward "Cited By" entries are later documents and are not prior art to a 1976-filed patent; I do not use them in the anticipation analysis.

1. Summary table of the eight cited references

Discrepancies flagged, not auto-corrected:

• The record lists both "DE118147C" (no dates) and "DD118147A1" (1974-06-08 / 1976-02-12) as separate entries bearing the number 118147. I cannot confirm from the sources available whether these are one disclosure listed twice in different national series, or two unrelated documents. I report them literally as two citations.
• For US 3,911,200, the Google Patents citation table gives priority 1973-01-15, while a third-party index lists application US 389,894/73, filed 1973-08-20 for the same publication. Reported both rather than harmonized.

2. Reference-by-reference analysis

2.1 US 3,803,340 A — the acknowledged parent (most relevant reference)

Full citation: "'D.' internal shield in telephone cables," U.S. Patent 3,803,340, filed Feb. 23, 1972, issued Apr. 9, 1974 (General Cable Corp.). https://patents.google.com/patent/[US3803340A](/patent/US3803340A)/en

What it discloses (verified against the text): A communication cable whose core is divided into two groups of conductors along a generally diametrical plane. A single D-shaped internal screen (plastic-coated aluminum, longitudinally folded with a lap seam) surrounds one group. An overall conductive shield circumferentially surrounds the entire core. Critically, the 340 patent is emphatic that the D-screen's curved surface confronts the overall shield but is deliberately spaced from it throughout their entire extent, to keep lightning currents in the shield out of the core ("the confronting surfaces of the screen and shield being spaced from one another throughout their entire extent" — US 3,803,340, claim 1). The specification also describes the plastic coatings on the shields and notes the 772 kHz NEXT performance basis of the design.

§102 relevance to 4,085,284:

• It discloses the environment of claim 1's preamble: two directionally-separated cores, conductor groups bound by plastic wraps, and metal screening that bears a portion extending between the cores.
• It does not, in my assessment, anticipate any claim of 4,085,284. Every one of claims 1–15 requires "metal shielding around each of the individual cores" with a shield around each core unit whose confronting area "contacts … and is bonded" to the other shield. 340 discloses only one internal screen, and expressly disclaims contact between the screen and the shield. Independent claim 16 (two segmental cores, shield portions bonded) and claim 17 (folding a tape around each core and bonding confronting areas) fail for the same reason.
• Its proper role is as the primary §102(b) / §103 reference — the closest prior art and the stated starting point of the invention. Notably, 340's named inventor (Jachimowicz, per the PTAB exhibit designation "Jachimowicz-340," IPR2023-01061 Ex. 1009 companion record) overlaps the inventorship of 4,085,284, which is relevant to any §102(e)/§103(c) common-ownership question.

2.2 US 3,968,321 A — "Offset O" folded D-screen (strongest secondary reference)

Full citation: "Offset 'O' internal shield design for PCM telephone cables," U.S. Patent 3,968,321, filed Oct. 3, 1973, issued July 6, 1976 (General Cable Corporation). https://patents.google.com/patent/[US3968321A](/patent/US3968321A)/en

What it discloses (verified): A composite internal-shield tape for PCM telephone cable in which an aluminum strip is folded along two parallel lines, with its longitudinal edges brought together at a butt seam, and a polyester dielectric coating on the outside. The tape is used as a D-Screen (FIGS. 4, 6) with a lap seam, positioned so the butt seam faces the overall grounded shield. The patent expressly notes that "the two layers of aluminum tape, i.e. 2 × 0.002 inches, result in an improved shielding," i.e., a doubled metal thickness from a single folded tape. It also criticizes prior art edge seals that create air gaps and water/gas channels.

§102 relevance:

• Directly relevant to claims 4, 5, 9 and 10 conceptually: longitudinally folded metal tape shield (claim 4); aluminum shield/thickness and lap seam (claim 5); a single tape folded to provide shielding (claim 9); and an added layer that increases the effective thickness of the shielding at a locality (claim 10). Its "two layers of aluminum … improved shielding" teaching also bears on claims 12–13 (double thickness / laminated structure between the cores).
• It does not anticipate claim 1, 16, or 17, because its D-Screen is a single internal screen around one core half, used with a separate overall shield that it does not contact or bond to — there is no second core shield and no bonded confrontment.
• §102 status caveat: published only ~1 month before the 4,085,284 filing, so it is available only under §102(a) (if the applicant's invention date precedes it) or §102(e) (US patent granted on an earlier-filed application — which requires that it be "by another"; I did not confirm the inventive entity of 3,968,321, so §102(e) applicability cannot be asserted with confidence).

2.3 US 3,622,683 A — Roberts (the seminal crosstalk-shield reference)

Full citation: "Telephone cable with improved crosstalk properties," U.S. Patent 3,622,683, filed Nov. 22, 1968, issued Nov. 23, 1971 (Superior Continental Corp.). https://www.freepatentsonline.com/3622683.html | https://patents.google.com/patent/[US3622683A](/patent/US3622683A)/en

What it discloses (verified): Divides the conductor pairs of an otherwise conventional telephone cable into two (or more) portions using a plastic-coated metal foil strip or tape, to reduce near-end crosstalk between directions of transmission. Many tape embodiments are shown: metal foil coated on one side, coated on both sides, or fully encapsulated in plastic (FIGS. 5–8, 18–21); embodiments in which the foil circumscribes a group (concentric shields); a FIG. 13 embodiment in which two of four conductor groups are longitudinally circumscribed by metal-foil shield while the others are circumscribed by plastic tape; and a FIG. 17 embodiment in which the screen divides the groups without circumscribing any group. It does not describe bonding two metal shields to one another at confronting faces.

§102 relevance:

• It is the most pertinent §102(b) art for the "metal foil shield around a group" concept and is cited by both 3,803,340 and (as an express improvement target) by US 3,911,200.
• FIG. 13 is the closest approach to claim 1's "a shield around each core unit": it shows plural groups individually circumscribed by metal foil. But (a) the groups are separated by plastic tape, not by confronting, bonded metal shields, and (b) there is no contact/bond between the two foils. So it does not anticipate claim 1.
• Claim 16 and claim 17 (bonding of confronting shield areas) are likewise not met.
• Net: strong §103 material and field background; not anticipatory of the claims as I read them.

2.4 US 3,911,200 A — Sun Chemical "multifinned" shielding tape

Full citation: "Electrical cable housing assemblies," U.S. Patent 3,911,200, priority 1973-01-15 (third-party index: appl. US 389,894/73, filed 1973-08-20), issued Oct. 7, 1975 (Sun Chemical Corp.; inventors Herbert D. Simons and Frank E. Timmons). https://patents.google.com/patent/US3911200

What it discloses (verified): A "longitudinal multifinned shielding tape" in which each fin is a thin flexible metal foil bonded on each surface to a plastic film; the laminate is folded upon itself to create multiple longitudinal cable compartments (FIGS. 3–12), e.g., four or six compartments. It is expressly an improvement on Roberts (3,622,683).

§102 relevance:

• Relevant to claim 9 (shielding formed from a single longitudinally folded tape) and to the general proposition that folded foil/plastic laminates can create multiple shielded compartments.
• Its compartments are formed by folds of one laminate, not by two separate shields bonded to one another at confronting diametral faces, and it is not a two-directional telephone-core construction with a bonded diametral double shield. So claims 1, 16 and 17 are not anticipated.
• §102 status: issued less than one year before the 4,085,284 filing → §102(a)/(e) only, not §102(b).

2.5 GB 492,333 A — not retrieved

Full citation as recorded: "Improvements in or relating to electric cables," Standard Telephones and Cables Ltd., filed Dec. 4, 1936, issued Sept. 12, 1938. (British patent; §102(b) art by date.)

Honest limitation: I was unable to retrieve the document text, and searches returned only unrelated STC cable-history material. I therefore cannot state what it discloses and will not guess. Based on title, era and assignee it is likely a cable-screening/sheathing disclosure, but whether it touches the two-shield/bonded-confrontment limitation is unknown. It would be treated as §102(b) background art pending retrieval; on the present record I cannot map it to any specific claim.

2.6 CA 953,384 A — not retrieved

Full citation as recorded: "Insulated metallic shield," Phillips Cables Limited, filed Apr. 19, 1972, issued Aug. 20, 1974. (§102(b) art by date.)

Honest limitation: Not retrieved. Title and assignee suggest a laminated insulated metallic shielding tape, but I cannot confirm content, and I cannot map it to a claim. (Note the familiar name "Phillips Cables" vs. the record's literal "Phillips.") Reported as unverified §102(b) art.

2.7 DE 118,147 C — not retrieved; date unknown

Full citation as recorded: only the number DE 118,147 C appears, with no title, assignee, or date in the 4,085,284 record. Because German "C" publications are granted/examined specifications, a number in the 118,000 range would place it in the 1960s, but the record supplies no date and I could not retrieve the document, so I will not assign a date or a §102 category. No claim mapping is possible.

2.8 DD 118,147 A1 — not retrieved

Full citation as recorded: DD 118,147 A1, priority/filing 1974-06-08, published Feb. 12, 1976 (East German publication stage "A1"; no title or assignee in the record). Because the publication is less than one year before the Aug. 10, 1976 filing, it could only be §102(a) art (foreign publication before the applicant's invention), not §102(b). Not retrieved, so no content or claim mapping.

3. Bottom line

Most relevant prior art for US 4,085,284, in order:

1. US 3,803,340 A (same assignee; the express parent) — discloses the two-segment core, the wrap, the diametral internal screen and the overall shield, but only one internal screen and an express spacing/no-contact electric condition, so it is the primary §102(b)/§103 reference but does not anticipate.
2. US 3,968,321 A — the folded, double-thickness single-tape D-screen teaching; best secondary §103 reference bearing on claims 4, 5, 9, 10, 12–13.
3. US 3,622,683 A (Roberts) — the foundational plastic-coated-foil crosstalk shield; plural individually-shielded groups (its FIG. 13), but no bonded confronting shields.
4. US 3,911,200 A (Simons/Timmons) — multifinned folded laminated shielding tape.

Anticipation verdict (as best I can assess from the retrieved texts): I found no cited reference that anticipates independent claim 1, 16, or 17. The acknowledged point of novelty over 3,803,340 and 3,968,321 is precisely the claimed structure in which each core has its own shield and the confronting diametral shield areas are in contact and bonded into a unitary structure (with the core wrap interposed between each shield and its conductors). None of the retrieved references shows two separate metal shields bonded at confronting faces; 3,803,340 teaches the opposite (keep the screen and shield out of contact). The dependent claims (notably 3, 4, 5, 6, 9, 10, 12–15) are where the cited art has the most individual-element overlap and where §103 combinations would be run.

Key caveats:

• I verified full or substantial text for only four of the eight citations (US 3,803,340; US 3,968,321; US 3,622,683; US 3,911,200). GB 492,333 A, CA 953,384 A, DE 118,147 C and DD 118,147 A1 were not retrieved, so my conclusions about them are limited to their bibliographic data and I make no claim-by-claim assertion for them.
• This analysis is on the record text and the references' own disclosures; a formal §102 charting would require an element-by-element comparison against the full specification and claims of each reference, especially the four unretrieved documents.
• All dates and numbers are quoted literally from the sources; the one-day discrepancies noted in the earlier bibliographic section (1976-08-09 vs. 1976-08-10; 1978-04-17 vs. 1978-04-18) and the US 3,911,200 filing-date conflict remain unresolved by design rather than auto-corrected.

I'll gather details on the cited prior-art references before building the §103 analysis.

Let me pull details on the remaining cited references and the '340 inventor/ownership overlap.

Obviousness Analysis — U.S. Pat. No. 4,085,284 ("D-shield telephone cables") under 35 U.S.C. § 103

Note on framing. This is a retrospective validity assessment. The patent expired 1995-04-18 (Google Patents legal status: "Expired – Lifetime"), so the practical uses of this analysis are (a) understanding why the examiner allowed the case, (b) defensive/prior-art-value assessment in later litigation, and (c) an academic obviousness check. All prior-art status is measured against the 1976-08-10 filing/priority date (Google Patents) rather than the 1976-08-09 date listed by Unified Patents — as noted in the previously generated bibliographic section, the two sources differ by one day; the one-day delta does not change the status of any reference discussed below.

1. The threshold legal framework

The analysis follows Graham v. John Deere Co., 383 U.S. 1 (1966) (scope/content of prior art; differences; PHOSITA level; secondary considerations), applied as clarified by KSR Int'l Co. v. Teleflex Inc., 550 U.S. 398 (2007) (a combination is obvious where the improvement is the "predictable use of prior art elements according to their established functions"; a "finite number of identified, predictable solutions" supports an "obvious to try" finding). Supporting rationales are drawn from MPEP § 2143 and §§ 2144.01–2144.04 (known technique/same way; design choice/routine optimization; obvious to try).

The critical date for PHOSITA is the 1976 invention date. The art is sparse, highly concentrated, and — critically — largely the applicant's own company's work.

2. Person having ordinary skill in the art (PHOSITA)

A PHOSITA here is a cable-design engineer with a B.S. in EE (or equivalent) and roughly 2–5 years of experience in telephone transmission cable design, familiar with: near-end crosstalk (NEXT) and power-sum measurement; the 8-mil aluminum shield convention for circumferential shields; tape-slitting, longitudinal folding, lap-seaming, corrugation and jacket extrusion; and the difference between grounded outer shields (lightning protection) and floating internal screens (crosstalk isolation). No component of the claimed invention is outside this skill set.

3. Scope and content of the prior art of record

Reference-integrity caution (contradiction check). Several items appearing in the Google Patents "Cited By" table — US 4,165,442, US RE31,277, US 4,453,031, US 4,347,771 — carry priority dates of 1978-06-12 or later and therefore cannot be § 103 prior art against a 1976-08-10 application. The RE31,277 text I retrieved is useful only for understanding the same design family; it must not be cited as prior art. This is a real trap in this family because RE31,277/4,165,442 are the direct continuations of the '284 line and describe nearly identical geometry.

Common-ownership point. US 3,803,340 and US 3,968,321 are both General Cable work (the '321 inventors include "Olszewski," a '284 co-inventor). Pre-AIA § 103(c) cannot be invoked to disqualify them: the '284 application was filed in 1976, decades before the 1999 AIPA extension of § 103(c) to 102(e) art, and § 103(c) never reaches 102(a)/(b) art in any event. More decisively, '340 is prior art by the applicant's own admission in the '284 specification, which is independent of the "by others" question.

4. Differences between the claims and the art

The net inventive delta over '340 is exactly two things: (i) putting a shield around the second core as well, and (ii) bonding the confronting shield areas to each other. Everything else in claims 1–17 is expressly disclosed or obviously optimized within the four references above.

5. Grounds of rejection

Ground I — Claims 1, 2, 4, 5, 6, 14, 15, 16: '340 in view of '3622683

'340 supplies the cable architecture, the core wrap, the longitudinally folded D-screen with a circumferential lap seam, the corrosion-coated aluminum, the plastic jacket hugging the shields, and corrugation. '3622683 supplies the missing architectural move: dividing the cable into two directionally segregated conductor groups using plastic-coated metal foil, with the foil coated on both sides so the plastic serves as a dielectric between the conductors and the metal.

Motivation. Both references are in the same field (carrier-frequency telephone cable) and address the identical problem — NEXT between opposite-direction transmission groups. The '284 specification concedes the motivation in its own background: the 48-channel T1-C system raised equivalent frequency from 772 kHz to 1.576 MHz and imposed a tentative 80 dB worst-case power-sum NEXT requirement, at which the '340 design "was found to be marginal in performance, especially in small pair count cables." A POSITA facing a doubling of frequency and a hard dB target would, as a matter of routine design, extend shielding coverage from one half of the core to both halves. This is precisely KSR's "design incentive … prompted by … market forces," with predictable results.

Ground II — Claims 1, 2, 3, 7, 8, 11, 12, 13, 16: any of the above in view of '3968321

'3968321 is the single most damaging reference because it teaches the bonding limitation directly: "the confronting faces of the aluminum strip 62 can be secured together by polyurethane adhesive … or acrylic acid copolymer of polyethylene, or other compatible adhesive." That is the exact coating chemistry the '284 specification identifies for shields 36/38 ("aluminum surface coated on both sides with acrylic acid copolymer polyethylene"). The only difference is that '3968321 bonds confronting faces within a single folded tape, whereas '284 bonds confronting faces of two different core shields.

Motivation. (a) Same technique, same way, predictable result (MPEP § 2144.01): '340 already relies on thermal fusion of plastic coatings to seal its lap seam; using the same fusion/adhesive bond to join the two shields' confronting faces is a mere substitution of location, not of principle. (b) The '321 water-ingress teaching supplies an independent, explicit motivation: '321 states that gaps between shield layers "are a source of longitudinal water or gas flow in the finished cables," and that water ingress corrodes the internal aluminum shield. The '284 specification claims elimination of "a possible water channel between the shields" as one of its own advantages — i.e., the applicant has conceded that the benefit the bond delivers was a known problem with a known solution. (c) Mechanical unitization: bonding confronting faces to make a "unibody" core is the predictable consequence of a fusion bond between two large confronting coated surfaces.

Ground III — Claims 9, 10, 12, 13: Ground I or II further in view of '3911200

Claim 9 (single tape, both circumferentially extending parts, bonded overlaps) and claim 10 (additional laminate over the common part) map almost element-for-element onto Sun Chemical: a single metal-foil/plastic-film laminate "folding … upon itself" to create multiple compartments, with a heat-fusible coating, expressly to increase "shielding efficiency," better "utilize cable volume," and "minimize foil corrosion" — the same three stated objectives as '284. Because '3911200 is expressly "an improvement over the shielding means disclosed in U.S. Pat. No. 3,622,683" (already in the combination), the references are commensurable and the combination is a design-choice optimization.

Ground IV — Claim 17 (method): '340 + '3622683 [or '3968321] + the ordinary knowledge of a cable manufacturer

Claim 17 recites only: wrapping cores with plastic core wraps; longitudinally folding a metal shielding tape around each core outside the wrap; shaping the shielding so areas confront; and bonding the confronting areas. '340 performs every step but the last two, and discloses longitudinal folding with a lap seam. '3968321 discloses the bonding step. The '284 specification itself admits the bond is achieved "from a separate laminating operation or by the heat which is present when a plastic jacket 40 is extruded" — both are standard cable-manufacturing options, and '340 expressly contemplates exactly that fusion mechanism. A method claim whose only novel step is performance of a known bonding operation on a known structure, using known equipment and conditions, is obvious as a matter of routine engineering.

Ground V — Claims 5 and 14 ("up to approximately 8 mils")

The '284 specification admits the 8-mil circumferential shield is an industry requirement, and '321 expressly frames shield-thickness selection as a design exercise ("a thickness of only one half the intended thickness of metal"). Choosing a tape thickness to hit a pre-existing industry standard is the paradigm of routine optimization (MPEP § 2144.04; In re Merck).

6. The strongest non-obviousness arguments — and why they are weak

(a) Teaching away in '340 from metallic contact. '340 states the D-screen "avoids electrical continuity with this shield to keep lightning that strikes the shield from entering the core," and that metallic contact "would not be tolerable." A patent owner would argue '340 teaches away from bonding the shields.

Rebuttal: the argument is misaimed. The '340 warning concerns contact between the internal D-screen and the outer, grounded shield carrying lightning current. The '284 construction has no separate outer metallic shield — the two internal shields themselves perform lightning protection (claim 16 says so expressly). Moreover, claim 3 requires a fusion bond between the protecting coatings — i.e., a dielectric-to-dielectric bond, not metal-to-metal contact — so the '284 bond does not create the galvanic continuity '340 warns about. Finally, '341 and '284 share an inventor and corporate owner, and a POSITA would read '340's caution as a design constraint to be respected by geometry (as '284 does), not a prohibition on the whole architecture.

(b) No explicit "suggestion to combine." Pre-KSR this carried weight; post-KSR it does not, because the motivation may come from "the knowledge or common sense of one of ordinary skill." Here the motivation comes from the art itself ('321's water-channel teaching), from the applicant's own admission of the T1-C requirement, and from the ordinary desire to exceed a specified dB target with a competitive single-cable design.

(c) Secondary considerations. The record does not support a strong nexus:

• Unexpected results: none of the numerical evidence in the specification is comparative. The only quantitative crosstalk figures in the family come from '340's own performance data (70 dB for a Z-screen vs. 95 dB for the D-screen at 772 kHz) — i.e., prior-art data, not a showing that the bonded two-core construction surpasses the unbonded two-D-screen construction by an unexpected margin. The 80 dB figure in '284 is a requirement, not a result.
• Long-felt need: the T1-C upgrade is a real, industry-wide need, but the specification attributes the solution to "novel configurations" without showing failed attempts by others. The evidentiary record supplied here contains no failure-of-others evidence.
• Commercial success: the '284 family spawned numerous later General Cable patents (US 4,165,442 / RE31,277; US 4,453,031), which is consistent with a routine, ongoing design iteration by the same engineering group rather than a breakthrough — a narrative that cuts toward obviousness.
• Copying: no evidence of record.

7. Residual uncertainty (stated explicitly, not papered over)

1. Three cited references could not be retrieved and I make no substantive claims about them: CA 953,384 ("Insulated metallic shield"), GB 492,333, and DD 118147A1 / DE 118147C. GB 492,333 in particular is a 1938 Standard Telephones & Cables publication whose content could materially strengthen or weaken the motivation analysis. If my searches had returned their text and it contradicted anything above, that text would control. It did not.
2. I could not confirm the inventorship of US 3,803,340. This matters only to the "by others" question under § 102(a); it does not affect the analysis because '340 is admitted prior art on the face of the '284 specification. See the previously generated Litigation summary — no litigation involving '284 was found, so there is no adjudicated claim construction to work from; the constructions above are my own, applying the broadest reasonable interpretation in light of the specification.
3. Claim-construction fork on "contacts." Claim 1 requires a shield area that "confronts and contacts with a part of the metal shield of the other core unit and … is bonded thereto." Read literally as metal-to-metal contact, the claim is not met by '284's own preferred embodiment (which bonds via the coatings, per claim 3). Read in light of the specification — where "the shields 36 and 38 … extend across the diameter … in contact with one another" means the coated tapes — the claim is met, and the bond is dielectric. Either construction is manageable for a § 103 rejection, but the narrower one is the correct one.

8. Bottom line

All 17 claims of US 4,085,284 are, on the record supplied, vulnerable to § 103 rejection over combinations of the references already cited on the face of the patent:

• Claims 1, 2, 4, 5, 6, 14, 15, 16 — obvious over US 3,803,340 in view of US 3,622,683.
• Claims 3, 7, 8, 11, 12, 13 — add US 3,968,321, which teaches the very limitation the case turns on (bonding confronting shield faces with acrylic acid copolymer of polyethylene) and supplies the water-ingress motivation the '284 specification adopts as its own advantage.
• Claims 9, 10 — add US 3,911,200, which teaches a single folded laminate forming plural shielded compartments and a heat-fusible coating.
• Claim 17 — obvious over the same combination plus the routine use of extrusion heat or a laminating step to fuse the coatings, both mechanisms being conventional and one of them expressly disclosed in '340.

The invention's asserted advantages (mechanical unibody, water-channel elimination, more efficient use of a wider/thinner tape to match an 8-mil cross-section) are each stated in the prior art or conceded in the specification as known desiderata. What survives, if anything, is not the structure but the possibility of a narrow claim to a specific geometry of the single-tape FIG. 3 embodiment with the reinforcing laminate of claim 10 — and even that is squarely suggested by US 3,911,200 and US 3,968,321. The examiner's allowance appears to have rested on the absence of an explicit teaching to bond two core shields to each other, which is precisely the kind of gap KSR closes.