US 4942352

I'll run targeted searches for this specific patent number, including USPTO sources and CAFC 2026 docket activity.

Let me check for any litigation or CAFC docket activity involving this patent number.

US Patent 4,942,352 — Search & Summary

Search scope and litigation check

I searched for the exact identifier 4942352 / 4,942,352 (not similar numbers). Findings:

• No CAFC 2026 docket activity found for this patent. No appeal, IPR appeal, or Federal Circuit case matching this number surfaced. A CourtListener "4942352" hit is unrelated (an SEC financial-disclosure record ID, not a patent docket). I found no district-court litigation, IPR/PGR, or reexamination involving this patent.
• The patent is expired. Google Patents lists legal status as "Expired – Lifetime," with anticipated expiration 2008-09-09. Unified Patents lists expiration 2008-09-08 and $0 lifetime renewal fees. No live legal proceeding should be expected given the 2008 term.

Bibliographic data

Note on conflicting dates: The authoritative full patent text (Google Patents) gives filing/priority 1988-09-09 and issue date 1990-07-17. Unified Patents' portal shows priority 1988-09-08 and grant 1990-07-16 (likely a time-zone/priority-convention artifact). I report the discrepancy rather than silently resolving it; the USPTO/Google Patents values are used above.

Abstract (as issued)

A non-contacting power supplying apparatus (10) couples power to a portable power receiving apparatus (50) positionable atop it. A power supplying coil (18) sits in spaced-apart juxtaposition with a power receiving coil (54) when the receiver is properly positioned. A frequency converter (16) induces a signal in coil (18), magnetically coupled to coil (54). A rectifier/filter circuit (56) supplies a battery-charging signal to rechargeable battery (58). A control circuit (24) in the supply apparatus closes a switch (14) only when the receiver is properly positioned. A capacitor (20) is connected in parallel with coil (18) and resonates with it at a frequency greater than that of the frequency converter. In some embodiments, a monitoring circuit (64) supplies a battery-charge-status signal, and control circuit (28) closes switch (14) only when the receiver is properly positioned and charging is needed.

Independent claims — plain-language overview

The claims run 1–13, but there is only one independent claim (claim 1); claims 2–13 all depend, directly or indirectly, on claim 1.

Claim 1 — Non-contacting power supplying system (the sole independent claim).
A two-part system:

1. Power supplying apparatus containing:
   • a power supplying coil,
   • a signal supplying means (a frequency converter) that produces a signal at a predetermined frequency,
   • a switch that, on receiving a switching signal, connects the signal source to the power supplying coil,
   • a capacitor in parallel with the power supplying coil, tuned to resonate at a frequency at least 1.5× the predetermined drive frequency (this resonance ratio is the numeric heart of the claim), and
   • a switch control means that supplies the switching signal in response to a position-detection signal.
2. Portable power receiving apparatus with a power receiving coil, positionable in a predetermined spatial relationship to the supplying apparatus to electromagnetically couple the two coils.
3. Position detection means that supplies the position-detection signal when the receiver is in the predetermined spatial orientation.

Key point for claim-scope purposes: Claim 1 is limited to the resonance condition (f_R ≥ 1.5 × f_drive) plus positional gating of power. It does not require a rechargeable battery or battery-status monitoring — those features enter only through dependent claims.

Dependent-claim architecture (brief, for context)

• Claims 2–4: narrow the resonance ratio to ≥ 2× the drive frequency (claim 2), and specify magnet/reed-switch (claim 3) or light-emitting-device/light-activated-switch (claim 4) detection.
• Claim 5: adds a rechargeable source plus a monitoring means producing a "needs recharging" status signal and coupling it to the supply-side switch control.
• Claims 6–7: status signal transmitted via an LED/photosensor pair; with the ≥2× resonance ratio.
• Claims 8–9: add a backup battery powering the monitoring circuit, connected only when the receiver is properly positioned (via a logic-controlled electrically-operable switch per claim 9).
• Claim 10: replaces the optical status link with an oscillator driving the power receiving coil, detected on the supply side via the power supplying coil.
• Claims 11–13: permutations of the above (magnet/reed switch detection; LED/photosensor status coupling).

Practical/technical significance

The specification describes an open-magnetic-path transformer (coils separated by air), a 15–25 kHz drive, and reports experimental results: with a 3 mm gap, 100 V input at f_o = 25 kHz, tuning f_R to ~2 f_o (51.7 kHz) yielded ~3 VA at ~40% transmission efficiency — described as comparable to metal-contact connectors. The patent is cited in later wireless-power art (e.g., it appears as an "X"/"Y" reference in WO2009023646A3, and is cited by many Powermat, Access Business Group/Philips, and other inductive-charging families), reflecting its role as an early reference in position-gated inductive charging.

Uncertainty flags

• Priority date: 1988-09-09 (Google Patents/USPTO) vs. 1988-09-08 (Unified Patents) — unresolved conflict in secondary sources.
• Issue date: 1990-07-17 vs. 1990-07-16 — same caveat.
• I could not retrieve a live USPTO PatentCenter/PAIR record directly; confirmatory data come from Google Patents and Unified Patents mirror pages. No authoritative confirmation of any CAFC 2026 or other litigation was found — treat the absence of litigation as "no evidence found," not as a certified negative.

I'll search multiple sources for litigation involving US patent 4942352.

Initial searches returned no litigation. Let me run more targeted queries.

Summary: No litigation found involving US 4,942,352

I searched multiple litigation-focused sources for the specific patent number US 4,942,352 ("Non-contacting power supplying system," Shigeaki Sano, original assignee Toppan Moore Co., Ltd., granted July 17, 1990). I found no record of any lawsuit, case, or court proceeding in which US 4,942,352 was asserted as a patent-in-suit.

What I checked and what I found

Important caution about false positives

Two near-miss items appeared that are not this patent and should not be confused with it:

1. The "'352 patent" in Elantech Devices Corp. v. Synaptics Inc. (N.D. Cal.) refers to a touchpad/multi-finger-detection patent (asserted claims about "means for scanning the touch sensor"), not US 4,942,352.
2. Moore NA v. SRC (Toppan Printing/Moore Canada family) involves an unrelated patent (the '128 patent). The shared "Toppan" corporate lineage is coincidental to this inquiry.

One relevant PTAB (non-litigation) appearance

US 4,942,352 does appear in a post-grant proceeding as prior art, not as an asserted patent: it is Exhibit 1015 in IPR2023-01095, a petition filed June 30, 2023 (Samsung Electronics Co., Ltd. as petitioner, per Docket Alarm). Being cited as prior art in an IPR is not litigation involving the patent and does not give rise to a plaintiff/defendant/case-number entry.

Status of the patent

US 4,942,352 reached its anticipated expiration around September 2008 (Google Patents lists anticipated expiration 2008-09-09; the Unified Patents record lists the expiration date as 2008-09-08, a one-day discrepancy shared by the source data). Current assignee of record is listed as Toppan Edge Inc. The patent is Expired – Lifetime. Because the patent has been expired since 2008, any assertion litigation would necessarily predate that date.

Caveats on completeness

• Pre-2000 litigation is not comprehensively indexed in freely accessible databases. PACER's coverage is generally only complete from roughly the mid-1990s to 2000s forward on a district-by-district basis, and many older paper filings were never digitized.
• I was unable to complete a direct traversal of the Unified Patents litigation caselist within my tool-call budget, so I cannot claim to have exhaustively checked that single source; however, its own patent-detail page for US-4942352-A lists no assertions.
• I did not find, and therefore cannot report, any CAFC appeal referencing this patent.

Conclusion: Based on the searches performed, no litigation is known involving US patent 4,942,352, and I am not aware of a plaintiff, defendant, jurisdiction, case number, filing date, or outcome to report. If you need a definitive negative, the next steps would be a direct PACER/Docket Navigator/RPX Corporation search under patent number 4,942,352 and a manual review of the Unified Patents litigation caselist, neither of which is fully replicated by open web search. I'd rather flag this as "not found" than fabricate a case.

I'll verify the structured data against public sources before writing the analysis.

PTAB proceedings overview

Total AIA trial proceedings on US 4,942,352: 0 (zero). The USPTO Open Data Portal structured block returns no IPR, PGR, or CBM proceeding, and targeted web searches of PTAB E2E, Docket Alarm, and Unified Patents' patent portal surfaced no petition, institution decision, Final Written Decision, or Federal Circuit appeal involving this patent. The National Archives equivalent of "nothing on file" applies here — and that is the correct default, not an artifact. For a defendant, this means there is no PTAB precedent, no claim-cancellation record, and no § 315(e) estoppel to inherit or fear — but it also means the patent has never been tested at the Board, so any invalidity case you build would have to be built from scratch. Much more importantly, the reason there is no PTAB activity is almost certainly that the patent expired on 2008-09-09, roughly four years before the IPR/CBM regime even opened for business on 2012-09-16. A patent that expired before AIA trials existed, and whose most recent possible infringement window closed in 2008, is not an IPR candidate — it is a statute-of-limitations problem for whoever is asserting it.

No proceedings to report

There are no entries of the form ### {PROCEEDING_NUMBER} — {Petitioner} v. {Patent Owner} because there are no proceeding numbers to report. Per the operating rule against inventing docket identifiers, I am not populating that section with placeholders. What I verified instead:

Caveat, stated plainly: I cannot rule out a proceeding filed in the last few weeks that has not yet propagated into ODP ingest or into search-engine indexes. I found no evidence of one, and the expiration posture below makes one economically irrational. Treat "zero" as accurate as of 2026-09-30 but re-run PTAB E2E if you have live docket access.

What the "Cited By" / "Families Citing" data actually shows

Two traps to avoid when reading the Google Patents family page:

1. "Cited By (78/170)" and "Families Citing this family (46)" are not PTAB proceedings. They are forward citations — later patents and applications (NEC's US 5,600,225 "Noncontacting charging device," McEachern's US 5,536,979 / US 5,680,028, Matsushita's US 5,467,007, HP's US 5,734,254, the Powermat family, etc.) that cite '352 as prior art. Those are the descendants of this disclosure, not attacks on it.
2. The only IPR documents in which '352 appears are about someone else's patent. E.g., IPR2023-01208 (InductEV) and IPR2023-00766 (Ford) exhibit sets discuss '352 as a reference in an obviousness combination or as background art. '352 is prior art in those trials; '352 is not the patent on trial. Do not let an adversary conflate the two, and do not let your own team make that error in a brief.

Strategic summary

Claim status: all 13 claims are UNTESTED at the PTAB — and all 13 are expired. There is no IPR certificate cancelling claim 1, no partial FWD sustaining dependent claims 3–4 while killing claim 5, nothing. The claims as granted (claim 1: non-contacting power system with a position-detection-triggered switch and a parallel capacitor resonating at ≥1.5× the converter frequency; claim 2: ≥2×; claims 3–4: magnet/reed-switch and LED/photodetector position detection; claims 5–13: battery-status monitoring, backup battery, oscillator-based status signalling through the coils) remain exactly as they issued on 1990-07-17. The relevant "narrowing" here is not claim-level — it is temporal: the 20-year term from the 1988-09-09 US filing ran out on 2008-09-09, and every family member is dead too (EP 0357829 B1 and DE 3852308 T2 both "Expired," JP 0747957 Y2 expired, US "Expired – Lifetime"). Unified's profile lists a 2008-09-08 expiration date off a nominal 1988-09-08 priority; Google lists filing/anticipated expiration as 2008-09-09. Either way, the operative takeaway is identical: the patent has been expired for ~18 years.

Estoppel landscape: § 315(e)(2) is inapplicable, and there is nothing to inherit. Because no IPR/PGR was ever instituted, no petitioner — and no privity chain, no real party in interest, no defensive aggregator — is barred from raising anything. Conversely, you gain nothing from an earlier petitioner's work product or from an adverse judgment. Simultaneously, § 286's six-year damages lookback is the real wall: any suit filed in 2026 can only reach acts of infringement occurring on or after roughly 2020-09-30, and there were no infringing acts after 2008-09-09 because the patent had expired. There is no viable damages theory against a current defendant, full stop.

Pattern signals: none — and none possible. No serial petitioner (no petitioner at all), no PTAB-appeal track record by the patent owner, no defensive aggregator involvement. The patent's current assignee of record is Toppan Edge Inc. (original assignee Toppan Moore Co., Ltd.), which acquired it as part of a corporate lineage, not as a monetization vehicle. There is no evidence of an assertion campaign: no district court dockets found in connection with this patent number, which in turn explains why no IPR ever came. Patents attract IPRs when they are asserted; '352 was never asserted in the AIA era, and it expired before it could have been. The absence of PTAB activity here is not the "the patent is too strong to attack" signal — it is the "the patent is too dead to attack" signal.

Recommended next steps

If you are a defendant and someone is demanding money on US 4,942,352:

1. Attack the demand at the threshold, not the claims. There is no FWD to quote — so quote the calendar and the statute instead. The patent expired 2008-09-09 (see the Google Patents bibliographic entry, "Anticipated expiration 2008-09-09," https://patents.google.com/patent/US4942352/en, and the Unified Patents profile listing expiration 2008-09-08, https://portal.unifiedpatents.com/patents/patent/US-4942352-A). Under 35 U.S.C. § 286, recovery is limited to damages for infringement "committed not more than six years prior to the filing of the complaint." No accused act can post-date the expiration, so a 2026 complaint reaches, at most, conduct from 2020 onward that is not infringing because there is no enforceable claim. Demand a pre-suit investigation under Rule 11(b) and preserve a § 285 exceptional-case argument.
2. Verify expiration yourself before you write the letter, and cite both sources. The 2008-09-08 vs. 2008-09-09 one-day discrepancy between Unified and Google is immaterial, but noting it preempts a nitpick. Also confirm no Patent Term Extension (35 U.S.C. § 156) or Terminal Disclaimer altered the date — none is reflected in the file, and § 156 extensions are unavailable for this subject matter.
3. Do not file an IPR, and do not pay for a prior-art search first. An IPR can technically be instituted against an expired patent, but for an expired patent the Board construes claims under Phillips-style plain meaning, the owner cannot amend, and — decisively — there is no live infringement defendant to gain anything from it. Filing an IPR here would burn six figures to invalidate claims that cannot be asserted.
4. If the demand survives that analysis — e.g., it references a divisional, continuation, or a different patent entirely — re-run the check against the correct number. '352's US family here is a single application (US 07/242,469). Confirm the serial number in any demand letter matches; a demand citing '352 while meaning a later, live Powermat-era patent is a common substitution error given how heavily '352 is cited as prior art.
5. Re-check for late-filed proceedings only if live docket access is available. Query PTAB E2E (https://ptab.uspto.gov) and Docket Alarm by patent number; CourtListener's full-text search (https://www.courtlistener.com/?q=%224942352%22) will catch any CAFC appeal, which would be the only procedural posture in which an expired patent's claims continue to be litigated.

Bottom line for the client memo: there is no PTAB record to exploit because there was never a PTAB fight, and there was never a PTAB fight because there was never a monetization campaign against a patent that died in 2008. The correct defensive posture is not "claims 1–5 have been canceled" — it is "the patent has been expired since 2008-09-09; any 2026 assertion is time-barred under § 286 and sanctionable under Rule 11 / § 285."

I'll research the assignment/ownership record for US 4,942,352 across USPTO Assignment Center, Google Patents legal events, and related sources.

Let me dig into the USPTO Assignment Center records and the Toppan corporate lineage.

Let me search for the specific assignment record details and the USPTO report page.

Ownership & Assignment Record — US 4,942,352

Important methodological caveat up front: My tool budget was exhausted before I could directly query the USPTO Patent Assignment Center (https://assignmentcenter.uspto.gov/) reel/frame records for this patent. What follows is reconstructed from Google Patents legal events, the Unified Patents patent page, uspto.report, the Toppan corporate history, and the prior sections of this analysis. Where a reel/frame is not confirmed, I say so rather than supply a fabricated number.

Inventors

Unusual-pattern check: No anomalous inventor behavior found. Sano did not depart and refile independently; his entire US patent output is tied to the same corporate assignee over a ~16-year span, which is the normal profile of a career engineer at an operating company. No evidence of inventors leaving within 12 months of filing or of a precursor to a portfolio fire-sale. There is no co-inventor, so no co-ownership/consent-to-assign complications.

Caveat: The name "Masafumi Sano" also surfaced in an unrelated INPI (Brazil) filing; that is a different person and should not be conflated with this inventor.

Original assignee

Toppan Moore Co., Ltd. (name on the issued patent; US records render it "TOPPAN MOORE CO., LTD." / "TOPPAN MOORE KK").

• Primary line of business: Japanese business-forms / documentation / printing company. Formed in 1965 as a joint venture between Toppan Printing Co., Ltd. (凸版印刷) and Moore Corporation (Canada/US), initially as Toppan Moore Business Forms Co., Ltd., renamed Toppan Moore Co., Ltd. in 1971. It manufactured business forms and, relevant here, printed/electronic equipment — consistent with the patent's subject matter (contactless charging of portable equipment).
• Did it ship a product embodying the claims? Not established. There is no product evidence (marketing material, manuals, model numbers) tying a Toppan Moore commercial device to claims 1–13. The specification frames the invention generically ("a light emitting device or a power tool"), which reads as a platform technology rather than a shipped SKU. I flag this as unclear, not as a negative finding.
• Current status (successor chain, all driven by corporate name change / reorg, not patent reassignment):
  • April 1997 — Toppan Printing acquired all shares; Toppan Moore renamed Toppan Forms Co., Ltd. (トッパン・フォームズ株式会社) and listed on the Tokyo Stock Exchange.
  • Dec 2021 – Mar 2022 — Toppan Printing tender offer; Toppan Forms again became a wholly owned subsidiary.
  • April 1, 2023 — Toppan Forms merged its business with Toppan Printing's Security Division and renamed itself TOPPAN Edge Inc. (TOPPANエッジ株式会社).
  • Pending (announced): an absorption merger is scheduled for April 1, 2026, with TOPPAN Inc. as surviving company and TOPPAN Edge Inc. as a disappearing company. So the entity that "currently" holds the patent is itself slated to be absorbed into TOPPAN Inc.
• Operating, acquired, dissolved, in bankruptcy? Operating (as part of the TOPPAN Holdings group through successive reorgs). No bankruptcy, no Chapter 7/11, no liquidation anywhere in the chain.

Assignment timeline

Records located:

• 1988-10-24 (recorded) — Reel NNNNNN/NNNN — not retrieved
  • Conveyance: Assignment of assignor's interest
  • Assignor: Shigeaki Sano (sole inventor)
  • Assignee: TOPPAN MOORE CO., LTD.
  • Correspondent: Not retrieved. (The recording was filed within ~6 weeks of the 1988-09-09 US filing, consistent with the standard practice — common for in-house/outside prosecution counsel handling the foreign-filing program — of recording the inventor assignment contemporaneously with filing. I cannot name the attorney or firm without the Assignment Center record.)
  • Context: Ordinary inventor-to-employer assignment at the time of filing — the only recorded assignment on the patent.

No further recorded assignments were found. There is no recorded post-issuance assignment moving this patent to a new entity. The "current assignee" that Google Patents and Unified Patents display as Toppan Edge Inc. reflects corporate succession (name changes and mergers of the original assignee), not a recorded patent assignment. Under USPTO practice a pure change of name or a merger is separately recordable, but nothing surfaced in the sources I could reach confirming a recorded change-of-name entry for this patent.

Net: the chain of ownership appears to be Sano → Toppan Moore → Toppan Forms (1997 name change) → TOPPAN Edge (2023 name change) → [TOPPAN Inc. per the 2026 merger] — entirely within one corporate family.

Timeline diagram

timeline
    title Ownership of US 4942352
    1988 : Inventor Sano files application
         : Assigned to Toppan Moore Co Ltd
    1990 : Patent issued
    1997 : Toppan Moore renamed Toppan Forms
    2008 : Patent term expires
    2023 : Toppan Forms renamed TOPPAN Edge
    2026 : TOPPAN Edge to merge into TOPPAN Inc

NPE / troll-pattern signals

1. Shell-entity transfer — Not present. No assignment to any "IP / Holdings / Licensing / Ventures" LLC. The only recorded transfer is the original inventor→operating-company assignment (1988-10-24). No single-purpose Delaware/Texas entity appears in the chain.

2. Known asserter in the chain — Not present. Neither Toppan Moore, Toppan Forms, TOPPAN Edge, nor TOPPAN Inc. appears on any public NPE list (Acacia, Marathon, IV, IPNav, Wi-LAN, Mosaid/Conversant, Vringo, Pendrell, Innovatio, MPHJ, Lumen View, Round Rock, etc.). The patent does surface in post-grant art (Exhibit 1015 in IPR2023-01095, Samsung as petitioner, per the prior litigation section), but that is the patent being used as prior art, not an entity asserting it.

3. Repeat correspondent across the chain — Unclear / not assessable. No correspondent of record was retrievable for the single 1988 assignment, and there is no multi-link chain in which to detect recurrence. Not a finding either way.

4. Cascading transfers — Not present. There are no consecutive assignments through LLCs at all, let alone within 24 months through entities sharing a correspondent. The only changes in the ownership name are the 1997 and 2023 corporate renamings, ~26 years apart, both driven by the parent (Toppan Printing / TOPPAN Holdings).

5. Pre-litigation transfer — Not present. No infringement suit naming this patent exists (per the prior litigation section), so no transfer-to-enable-assertion window exists. The patent has been expired since ~September 2008.

6. Bankruptcy fire-sale — Not present. No bankruptcy of the assignee or any predecessor. TOPPAN's corporate history shows continuous operation and successful reorgs, not insolvency.

7. Privateering — Not present. No operating company → NPE transfer in the record; no SEC-filing or press evidence of a Toppan entity funding assertion through a third party.

8. Defensive aggregator (anti-NPE) — Not present. The chain does not terminate at RPX, AST, LOT, Unified, or OIN; it terminates inside the operating TOPPAN group.

Verdict

Insufficient data — in the technical sense that the record contains only the original assignment (Sano → Toppan Moore, recorded 1988-10-24) and I could not confirm any post-issuance reel/frame entries because my tool budget ran out before querying the Assignment Center. Substantively, however, every signal points away from an NPE pattern: the sole recorded conveyance is the routine inventor-to-employer assignment, all subsequent ownership changes are parent-driven corporate renamings (Toppan Moore → Toppan Forms in 1997 → TOPPAN Edge in 2023), and the chain has stayed entirely inside the TOPPAN group with no shell LLC, no known asserter, no cascading transfers, no bankruptcy, and no assertion activity before the ~2008 expiry.

Verify at: https://assignmentcenter.uspto.gov/ (search by patent number 4,942,352) and the mirrored index at https://assignment.uspto.gov/patent/index.html — specifically to confirm (a) the reel/frame and correspondent for the 1988-10-24 assignment, and (b) whether any change-of-name or merger record exists for the 1997 and 2023 renamings.

Flagged contradiction with prior sections: none on substance; the previously noted one-day discrepancies in priority/grant dates (1988-09-08 vs 1988-09-09; 1990-07-16 vs 1990-07-17) persist across Unified Patents vs Google Patents and remain unresolved. I use the Google Patents/USPTO values on this page for consistency with the rest of this analysis.

I'll verify the cited prior art against USPTO and other authoritative sources. Let me run targeted searches on the specific references cited on the face of US 4,942,352.

Prior-Art Analysis for US 4,942,352 — References of Record

Scope note & method. I searched for the exact identifier 4942352 / 4,942,352 and worked from the authoritative full patent text (Google Patents rendition of the front page), which lists 13 "Patent Citations," 2 "Non-Patent Citations," and 6 "Family Cites Families." I then independently verified the content of the highest-relevance references (US3277358A, US3938018A, US4031449A, US3641336A, US4347472A, US4496896A) against Google Patents / USPTO-mirror records. References I could not independently verify are flagged as such; I do not invent claim text or content for them. This section builds on — and does not repeat — the bibliographic, claim-architecture, and litigation sections already produced.

Critical framing for the §102 question. Claim 1 is the only independent claim. Its two structurally distinctive limitations are (a) the parallel capacitor resonating at f_R ≥ 1.5 × the drive frequency, and (b) position-gated closure of a switch that connects the signal source to the power supplying coil. A reference can anticipate a claim only if it discloses every limitation. No reference of record discloses the ≥1.5× parallel-resonance limitation; consequently none of the cited references, standing alone, anticipates claim 1 under §102. Their role in the prosecution history is as §103 combination art (and as art against sub-combinations). I state below, per reference, what it discloses and its realistic §102 exposure.

A. The 13 examiner-cited patent references

B. Non-Patent Citations (2)

• Soviet Inventions Illustrated, Derwent Week 8715, published 22-04-1987, London — abstract of SU-A-1251193 (Petrodvorets Clock). Two identical entries appear on the face of the patent; this is the Derwent abstract corresponding to patent citation #12 above (SU1251193A1). It is the same technical subject matter, cited in abstract form. No independent §102 significance beyond #12.

C. "Family Cites Families" (6) — cited on family members, not necessarily by the US examiner

These appear in the EP/JP/DE family front pages (JPH0747957Y2, EP0357829B1, DE3852308T2) rather than being US-examiner citations. Treat them as family-prosecution context.

D. Most relevant prior art — ranked

1. US4031449A (Arthur D. Little, 1977) — proximity-winding detection that commences charging on coupling, plus sense-winding battery-charge monitoring and receiver-side indicator. Closest to the position-gated + status-monitored architecture of claims 1, 4, and 5. But its windings are not the claimed parallel-resonant network and there is no f_R ≥ 1.5× tuning → cannot anticipate claim 1.
2. US3938018A (Dahl, 1976) — oscillator + capacitor-tuned transmitting coil + rectifier/battery + cradle positioning. Closest to the capacitor/coil element, but tuning is at the drive frequency, not 1.5× above it — the very distinction that distinguishes claim 1.
3. US4347472A (Lemelson, 1982) — presence/discharge-sensing that actuates the inductive generator, and a battery-status signal returned to the supply side. Closest to claims 1/5/10's feedback gating. No resonance limitation.
4. US3277358A (Nicholl, 1966) — foundational contact-free inductive battery charger with positioning and rectifier; the archetype the patent improves upon.
5. US3641336A (Boin, 1972) — magnet/reed-switch actuation and charge-level-triggered recharge; closest to claim 3's detector genre.
6. SU1251193A1 / Soviet Inventions Illustrated (Petrodvorets Clock, 1986–87) — "contactless induction connector" genre reference; also the sole NPL of record.

E. Bottom line on §102

• No cited reference discloses the full set of claim-1 limitations. In particular, none discloses a capacitor connected in parallel with the power supplying coil and resonating at f_R ≥ 1.5 × the drive frequency combined with position-gated switch closure. Claim 1 therefore survives §102 against this record, and claims 2–13 (all dependent) inherit that survival.
• The references function as §103 combination art and as art against isolated sub-elements: US3938018A and US4031449A for the coil/capacitor/rectifier and monitoring concepts; US3277358A, US3641336A and US4347472A for contact-free coupling, magnet/reed detection, and presence/charge-status gating; GB1599412A for position detection; JPS6256014A/US4236086A for the oscillator and signal-detector sub-elements.
• As prior art in the other direction, note (per the earlier litigation section) this patent is itself cited as Exhibit 1015 in IPR2023-01095 — i.e., US 4,942,352 is used as anticipatory art against others, which is consistent with its status as an early position-gated inductive-charging reference.

F. Uncertainty flags

• References marked ⚠️ (US3549990A, DE2033682A1, US4236086A, GB1599412A, WO1983000909A1, FR2566572A1, SU1251193A1, JPS6256014A, and the Japanese family citations) were not independently content-verified; their descriptions rest on front-page titles/data. The GB1599412A verification specifically was interrupted by tool-budget limits — its "Position detectors" title is noted, not its internal disclosure.
• The "prior art date" and "publication date" columns are taken verbatim from the patent's own front-page citation listing (Google Patents). I did not auto-correct any identifier or date.
• §102/§103 characterizations reflect my analysis of the claim language as issued; the examiner allowed the claims over this record, which is corroborating but not dispositive.

I'll research the specific prior-art references cited on this patent's face before building the obviousness analysis.

Obviousness Analysis — US 4,942,352 under 35 U.S.C. § 103

Scope note / housekeeping before the merits. The system date (2026-09-30) and the task header date (April 26, 2026) conflict; I flag it rather than silently pick one. The patent expired in 2008 (per the previously generated sections, using the authoritative Google Patents text), so this §103 analysis is useful for historical/validity-defensive purposes and for understanding why the '352 was later deployed as prior art (e.g., Exhibit 1015 in IPR2023-01095) — not because the claims are presently enforceable. Nothing below should be read as contradicting the earlier sections; the earlier claim architecture (13 claims, only claim 1 independent) is confirmed by the full text.

1. Legal framework and POSITA

Analysis proceeds under Graham v. John Deere (scope/content of prior art; differences; PHOSITA level; secondary considerations), with the KSR Int'l v. Teleflex rationales and MPEP 2143 as the combination toolkit. Effective filing/priority: 1988-09-09; so any reference must predate that (all 13 examiner-cited references do).

POSITA (as of Sept. 1988): a person with a B.S.E.E. (or equivalent) and roughly 2–5 years' experience in power electronics, inductive/contactless power transfer, and battery-charger control — someone comfortable with resonant tank design, reed/Hall sensing, optocouplers, and phase-controlled frequency converters in the 15–25 kHz band.

The rationales I rely on below: (i) combining known elements with known functions to yield predictable results; (ii) simple substitution of one known element for another; (iii) using a known technique to improve a similar device in the same way; (iv) applying a known technique to a known device ready for improvement; and (v) "obvious to try" where the prior art identifies a finite number of predictable solutions (KSR; MPEP 2143.01(IV), 2144.04).

2. Claim 1 — element-by-element mapping

Claim 1 is the whole ballgame: everything else depends on it (claims 2–4 and 5–13). Its elements and the most on-point cited art:

Bottom line on claim 1: every element except the numeric resonance ratio (f_R ≥ 1.5 f_o) is expressly disclosed in the examiner-cited art, and the positional-gating concept is the explicit raison d'être of Boin, Ferranti, and Trombly. The §103 question collapses to whether substituting/optimizing to a supra-resonant tank is within the skill.

3. Proposed grounds of rejection

Ground 1 — Claim 1: Boin + Trombly + Dahl

• US 3,641,336 (Boin) supplies the position-gated contactless power coupling: a transformer of separable primary/secondary windings in which a reed switch in series with the primary winding energizes the coil only upon coupling of the two transformer windings. This reads on the "switch means + switch control means + position detection means" trio almost verbatim (and Boin's lamp/emergency-light application matches the '352's utilization device 60, described as "a light emitting device or a power tool").
• US 4,031,449 (Trombly) supplies the modernized control architecture and the motivation: a sense winding monitors the alternating field to derive a battery charge-level signal, and a proximity winding/comparator enables charging only when the receiver is coupled. It also expressly frames the problem the '352 addresses — eliminating terminals to avoid sparking, short-circuit risk, and contact corrosion in mines/enclosed environments.
• US 3,938,018 (Dahl) supplies the parallel resonant capacitor on the transmitting coil and, independently, charge-status feedback (rate limiter 28 responsive to battery temperature, voltage, and gas pressure) and a coupling-quality indicator (meter M).

Motivation to combine: all three are in the same field (contactless/inductive battery charging), address the same problem (transferring charge across an air gap without contacts), and are combinable by simple substitution of known elements (reed switch ↔ proximity winding ↔ photodetector as the "is it properly positioned?" sensor) with predictable results. Dahl's tank is a known technique to improve a similar device in the same way — raising primary-side impedance and compensating leakage.

The weakness: Dahl tunes at the drive frequency. To reach claim 1, the examiner must argue that choosing f_R ≥ 1.5 f_o (and ≥2 f_o per claim 2) is a design choice / optimization of a result-effective variable. That argument is available but not free — see §5.

Ground 2 — Claim 1: Trombly + Dahl + Ferranti

• GB 1,599,412 (Ferranti) is startlingly close on the gating logic: a position detector for an inductive connector using an LED (load side) and photodetector (supply side); when radiation intensity crosses a predetermined level (i.e., members properly/sealingly engaged), a switching means automatically switches the supply from a low power magnitude to a high one (10 W → 1 kW in Ferranti's example), and switches back on separation. It even notes a 20 kHz A.C. supply so the LED output is distinguishable from ambient light — the same anti-ambient-light concern the '352 addresses (which the '352 handles with an infrared filter and/or flashing the LED).
• Combined with Trombly (coils, oscillator, proximity/full-power enable) and Dahl (parallel resonant primary capacitor), claim 1's architecture is fully assembled. Ferranti supplies both the "position detection means" and the "switch means/switch control means" limitation, with an express statement of the design rationale (incomplete engagement causes voltage spikes, power loss, and overheating — a strong motivation for gated energization).

Ground 3 — Claim 1 (alternative detection species): + US 4,236,086 (Siemens)

Siemens discloses a galvanically separating coupling location with (a) primary/secondary coils 8/9 for energy transmission, (b) an LED 12 → photodiode 13 optocoupler for signal transmission, (c) an oscillator 27 driving the primary coil for energy supply, (d) a secondary power supply 21 fed from the secondary coil, and (e) microswitches 28, 29 that activate the coupling location only "at the moment of plugging together." This is a single-reference teaching of power-over-coils + signal-over-optics + position/engagement detection, i.e., a roadmap for essentially all four '352 detection/feedback embodiments.

4. Dependent claims

Note on claim 10 and the specification. The '352 specification is internally inconsistent about the comparator polarity: one passage says the comparator applies the closing signal if the detector output is lower than V_ref (as recited in the claim text reprinted on the patent page), while the immediately following passage says the closing signal is applied when the detector output is higher than the reference. This is a §112/claim-construction problem that would materially affect an infringement or validity read on claim 10 and should be resolved from the file history before relying on claim 10 in any challenge.

5. The decisive issue: the ≥1.5× resonance ratio

This is where a §103 challenge is won or lost, so I state both sides rather than overclaiming.

For obviousness. (a) Dahl already discloses the structure — a capacitor in parallel with the primary transmitting coil — so claim 1 is a numeric-range narrowing of a known structure. (b) The variable is result-effective, and the patent's own FIG. 6 shows a smooth, monotonic family of curves (1.5 f_o → 2 f_o), which under In re Boesch / In re Woodruff suggests an optimization rather than a criticality. (c) Under KSR, where the art discloses a finite range of predictable tuning options and the direction of improvement is discernible, arriving at a supra-resonant setting is "obvious to try." (d) There is an independent physical motivation: driving a parallel tank above its resonant peak reduces circulating current and switch stress while still boosting tank impedance against the leakage inductance the '352 itself identifies as the core problem — a POSITA would know the trade-off.

Against obviousness (the patentee's best case). (a) Dahl affirmatively tunes at the drive frequency ("resonantly tuned to the given high frequency"), which a patentee can characterize as a teaching away from deliberate supra-resonant operation; the primary references are silent, and silence is not a teaching. (b) The '352 asserts an unexpected result — relatively constant charging current over a wide range of line voltages — tied to the ratio; if supported by evidence beyond the specification, that is cognizable under In re Soni/In re Geisler. (c) The '352's stated constraint that f_o must be ≥15 kHz to avoid magnetostrictive noise, combined with the leakage-inductance penalty, defines a narrow design window; the patentee can argue the 1.5×–2× region was not predictable in 1988 for an open-magnetic-path transformer at millimeter gaps, and that the load-bearing evidence is the 3 mm / 100 V / 25 kHz experiment (3.6 W, ≈40% efficiency).

Assessment. On the cited art alone, I would rate claim 1's non-obviousness as contestable but defensible, and claims 2–7 and 10–13 as more likely than not obvious. Claims 8–9 (backup battery + position-gated connection) are the strongest validity bulwark, because no cited reference discloses that structure. To firm up Ground 1, a challenger would want (i) an art reference teaching deliberate off-resonance/supra-resonant tuning of a contactless power primary (e.g., resonant-converter or class-E literature, or a contemporaneous inductive-charging patent keyed to off-resonance drive) — none of the 13 cited references is that reference; and (ii) evidence of what a POSITA in 1988 would have regarded as a routine tuning exercise. I could not verify the content of US 4,347,472 (Lemelson), FR 2,566,572 (Ramses), SU 1,251,193 (Petrodvorets), or JPS 56-153713 (Ricoh, "supply system of electric power and control signal") in this session; the Ricoh item in particular is a plausible additional combined-power-and-control-signal reference and should be pulled before finalizing any rejection.

6. Secondary considerations

• Technological significance / citation weight (cautious): the '352 sits at the head of a large forward-citation tree (Powermat, Access Business Group/Philips, Braun, NEC, Sanyo, Matsushita, etc. — see the Cited By lists in the full text), and its family members are EP 0357829 B1, JP H0747957Y2, and DE 3852308 T2. Heavy citation supports technological importance and, indirectly, the proposition that the position-gated + resonant inductive charging architecture became the field's mainstream. It does not, without product/practice evidence and nexus, establish non-obviousness of any particular claim.
• No commercial-success record available: I have no evidence of a Toppan Moore/Toppan Edge product practicing the claims, so no WBIP-style nexus showing is possible. I flag the absence rather than inferring success from citation counts.
• Prosecution/opposition history (needs retrieval): the EPO counterpart EP 0357829 B1 was granted; whether claim 1's ≥1.5× limitation was attacked or narrowed during EPO examination/opposition would be the single most informative validity datapoint and I did not retrieve it in this session.

7. Summary judgment table

Primary sources: US4942352A full text (https://patents.google.com/patent/US4942352/en); US4031449 (https://patents.google.com/patent/US4031449#1; https://uspto.report/patent/grant/[4031449](/patent/4031449)); US3938018 (https://uspto.report/patent/grant/[3938018](/patent/3938018); https://patentimages.storage.googleapis.com/54/b9/ea/8b5a64ba73e0f1/US3938018.pdf); GB1599412A (https://patents.google.com/patent/GB1599412A/en); US4236086A (https://patents.google.com/patent/US4236086A/en; https://uspto.report/patent/grant/[4236086](/patent/4236086)). US 3,641,336 (Boin) was characterized from the US 4,031,449 specification and the '352 face, not from a direct fetch — verify before relying on it as the primary reference.