US 11360158

I'll search for litigation and docket information on this patent, then summarize.

Let me run a few more targeted searches to check for litigation or PTAB proceedings.

Summary of US Patent 11,360,158

Search scope note: I ran targeted searches for patent number 11,360,158 against public patent records, PTAB/PTACTS document repositories, and 2026 Federal Circuit (CAFC) materials. I found no active CAFC appeal, IPR/PGR, or district-court litigation naming this specific patent as an asserted patent. I cannot directly query PAIR/PatentCenter or the CAFC docket APIs, so treat the absence of litigation as "not found in public web sources," not as an authoritative negative. I did not find any record that the number has been reissued, disclaimed, or transferred away from Denso.

All bibliographic and claim content below is grounded in the authoritative full text of the patent (Google Patents, https://patents.google.com/patent/[US11360158](/patent/US11360158)/en).

Bibliographic data

Abstract

An insulation resistance measuring apparatus calculates a complex impedance of an AC circuit that includes a measuring resistor, a coupling capacitor, an insulation resistor installed in a vehicle, and a ground capacitance. The apparatus includes a sine-wave current applying device that applies an AC signal to the measuring resistor and measures a voltage change appearing at a junction of the current applying device and the measuring resistor (not between the coupling capacitor and the measuring resistor). The AC signal and the voltage change are used to determine the complex impedance, and a resistance value of the insulation resistor is calculated as a function of the complex impedance. The stated benefit is a smaller circuit because the detector's required voltage withstand is reduced by the measuring resistor.

Claims

The patent has 5 claims, with one independent claim (claim 1) and four dependent claims (2–5).

Claim 1 — independent (apparatus). A four-part apparatus:

1. A coupling capacitor connected at a first end to a power-supply path leading to a DC power supply;
2. A measuring resistor connected to the second end of the coupling capacitor;
3. A current applying device connected to the measuring resistor that applies an AC current to it;
4. A detector that detects a voltage change at the junction of the current applying device and the measuring resistor when the AC current is applied; and
5. A calculator that computes a complex impedance of an AC circuit (which includes the measuring resistor, coupling capacitor, an insulation resistor between the power-supply path and ground, and a grounding capacitance) using the AC current and the detected voltage change, and determines the insulation resistor's resistance value from that complex impedance.

Plain language: Drive an AC current through a measuring resistor into a coupling capacitor tied to the high-voltage bus; sense the voltage wiggle at the node between the current source and the measuring resistor; from that, derive the complex impedance and back out the insulation (leakage) resistance. Sensing on the low-voltage side of the measuring resistor keeps the sensor electronics low-voltage-rated, shrinking the circuit.

Claim 2 — dependent on claim 1. The detector computes a first product of (a) a first reference signal synchronous with the AC current and the voltage change, and a second product of (b) a second reference signal (out of phase with the AC current by a given angle) and the voltage change; the calculator then derives the complex impedance from these two products. Plain language: Use lock-in / quadrature detection (in-phase and phase-shifted reference mixing) to extract the real and imaginary parts from the sensed signal.

Claim 3 — dependent on claim 2. The two reference signals are 90° out of phase.

Claim 4 — dependent on claim 1. The current applying device cyclically sweeps the AC current frequency over a measuring range; where the frequency changes but the complex impedance stays constant, and the real part (or absolute value) is not equal to the measuring resistor's resistance, the calculator determines the insulation resistance from the real part/absolute value (i.e., the "flat" plateau equals Rs + Rg = Rtotal; subtract Rs). Plain language: Frequency-sweep method — find the plateau where |Z| is constant, and if it isn't just Rs, it's the total, so subtract Rs to get the insulation resistance.

Claim 5 — dependent on claim 1. The current applying device cyclically sweeps frequency; the calculator finds the point where the imaginary part of the complex impedance is maximized, subtracts the measuring resistor's resistance from the real part at that point and multiplies by two to obtain the insulation resistance. Plain language: Semicircle method — at the peak of the imaginary (reactive) part, Rg = 2 × (Re_Z − Rs). This version tolerates a smaller coupling capacitor.

Independent-claim overview

The only independent claim is claim 1, directed to the core architecture: coupling capacitor → measuring resistor → current-applying device, with the voltage detector tapping the node between the current-applying device and the measuring resistor (rather than between the coupling capacitor and the measuring resistor), and a calculator deriving insulation resistance from the complex impedance. Claims 2–3 add lock-in detection details (quadrature reference signals), while claims 4–5 add two distinct frequency-sweep algorithms for extracting Rg (constant-|Z| plateau and maximum-imaginary-part/semicircle).

Verification / confidence

• Bibliographic data and claim text: high confidence (taken from the authoritative full patent text).
• Inventor = Tomomichi Mizoguchi and assignee = Denso: high confidence, corroborated by an independent inventor profile page (patentleaderboard.com lists US 11,360,158 with grant date 2022-06-14 under Tomomichi Mizoguchi at Denso).
• Litigation/CAFC status: low confidence for a definitive negative. No CAFC 2026 docket, IPR, or district-court assertion of this patent appeared in search results, but I could not directly query the CAFC docket or USPTO PTAB systems, so I cannot rule out an unindexed proceeding.
• One caution on search noise: the bare string "11360158" matches unrelated records (a German equipment listing, a Brazilian corporate notice, a PMID, etc.). None of those relate to this patent; I excluded them. If you need a court-proof litigation check, this should be confirmed directly against PACER, the CAFC docket, and USPTO PatentCenter/PTAB (PTACTS) rather than web search.

I'll search for litigation involving US patent 11360158.

Let me try more targeted searches.

Let me search the Unified Patents portal and other litigation databases directly.

Summary of Search Results

I searched for litigation specifically involving US Patent 11,360,158 (Denso Corporation, "Insulation resistance measuring apparatus," granted 2022-06-14). I did not find any.

Known litigation: None found

No litigation (district court, ITC, or PTAB) involving U.S. Patent No. 11,360,158 was identified. I could not locate any plaintiff, defendant, jurisdiction, case number, filing date, or outcome for this patent.

Important caveat about false matches

My searches returned several hits that contain similar-looking numbers but are not this patent. Because you instructed me to interpret identifiers literally and not conflate similar numbers, I flag these as non-matches, not evidence of litigation:

• "Patent No. 10,013,158" — appeared in a PTAB filing (IPR2020-00705, Unified Patents v. Motion Offense, LLC). This is U.S. Patent 10,013,158, a different patent number (10 million series) from the 11 million-series 11,360,158 in question.
• A Brazilian corporate-registry filing containing the string "11360158" (a company registration entry, "J.S. FAGUNDES LTDA") — unrelated.
• A Chinese regulatory penalty table listing "11360158" as an entry ID — unrelated.
• Various Denso "automotive parts" antitrust/class-action matters (e.g., Sheridan Chevrolet et al. v. Denso Corp., Canadian courts) — these involve Denso as a corporate defendant in competition cases, not assertions of '158 or any litigation over this patent.

Additional context on why litigation is unlikely (but not impossible)

• The patent is Denso-held (an operating company, not a known NPE), which typically does not engage in wide assertion campaigns.
• It was granted only recently (June 14, 2022), so any litigation window is relatively short.
• The patent remains Active with a maintenance fee paid (4th-year fee, recorded 2025-12-03), consistent with continued ownership and no litigation-driven assignment.

Recommendation / next steps

Because my search tools returned no confirmed litigation, I cannot state with high confidence that none exists — only that I found none. To verify conclusively, the authoritative sources to check are:

• PACER (all U.S. district court dockets; search patent number in the case query)
• Unified Patents Litigation Portal: https://portal.unifiedpatents.com/litigation
• USPTO PTAB (Patent Trial and Appeal Board) for any IPR/PGR/CBM: https://portal.unifiedpatents.com/ptab
• USITC EDIS for any Section 337 investigation
• CAFC docket for any appeal arising from the above

If it would be helpful, I can run further targeted searches against those specific databases.

I'll verify the ODP "no proceedings" result against public sources before finalizing.

Let me run a few more targeted checks before concluding.

PTAB Proceedings Report — US Patent No. 11,360,158 B2

Patent: Insulation resistance measuring apparatus | Assignee: Denso Corp | Inventors: Tomomichi Mizoguchi
Priority: 2019-07-08 | Filed: 2020-07-08 | Granted: 2022-06-14 | Adjusted expiration: 2040-09-11
Claims: 5 total (five apparatus claims; claims 1 and 4–5 independent-form, with 2–3 depending from 1)

Proceedings overview

There are zero AIA trial proceedings on file against US 11,360,158. The USPTO Open Data Portal returns no IPR, PGR, or CBM proceedings for this patent, and independent web searches of PTAB decisions, docket aggregators, and Federal Circuit materials (searched 2026-09-29) surfaced no petition, no institution decision, no Final Written Decision, no termination, and no CAFC appeal naming this patent. The breakdown is therefore 0 active / 0 claims invalidated / 0 claims sustained / 0 settled / 0 institution-denied — all five claims stand untested in an AIA forum.

Bottom line for a defendant: this is emphatically not a "canceled claims" situation, and it is not a "hardened by surviving IPR" situation either. It is a clean, unchallenged patent. Nothing about PTAB outcomes helps you today, and equally nothing about PTAB estoppel constrains you. If you are being asserted against, all AIA invalidity routes are still open (subject to the § 315(b) statutory bar — see below), and you would be the first challenger, which carries both opportunity (no adverse claim constructions or Fintiv blowback from a prior panel) and risk (no free roadmap from a prior petitioner).

Proceedings

None on file

No AIA proceeding number exists to report, and I will not manufacture one. Nothing in the structured ODP block, the patent's Google Patents family record, or public docket sources discloses any petition against US 11,360,158.

For completeness, the record shows:

• No IPR — a petition would appear in the patent's PTAB E2E record and would typically be reflected in the "PTAB proceedings" data. Nothing.
• No PGR — the 9-month PGR window (from grant on 2022-06-14) closed on 2023-03-14. PGR is now statutorily unavailable regardless of interest.
• No CBM — CBM never applied (no financial-services business-method claims) and the CBM program sunset on 2020-09-16.
• No derivation, no reexamination reflected in the legal-events log (only routine assignment, docketing, office actions, and maintenance-fee activity through the 2025-12-26 4th-year fee payment — page shows the fee paid 2025-12-03).
• No Federal Circuit appeal found (no CAFC docket citing this patent).

⚠️ Caution against near-number conflation. Web searches returned hits for U.S. Patent No. 10,013,158 (Unified Patents, LLC v. Motion Offense, LLC, IPR2020-00705) and for U.S. Patent No. 11,316,014 (Semiconductor Components Industries v. Greenthread, IPR2024-00263). These are different patents and have nothing to do with US 11,360,158. I flag them only so they are not mistaken for activity on this patent. Per the identifier-integrity rule, I am not treating any of them as this patent's record.

Why this absence is plausible (not an artifact): 11,360,158 is owned by Denso Corporation, a large operating automotive supplier — not an NPE. It is a component-level insulation-resistance measurement patent tied to Denso's in-vehicle motor control / battery hardware. Patents like this typically get asserted (if at all) in supplier-vs-supplier or OEM supply-chain disputes rather than mass NPE campaigns, so they generate far fewer IPRs. The absence of PTAB activity is consistent with a patent that has not yet been brought into a contested assertion campaign.

Strategic summary

Claim status: all five claims UNTESTED. Claims 1–5 have never been before the Board. There is no canceled claim, no sustained claim, and no claim that has been narrowed by certificate of correction or reissue in an AIA context. Any statement that a particular claim "survived" or "fell" would be fabrication — neither has happened. Because claim 1 is the only claim with the full coupling-capacitor/measuring-resistor/current-applying-device/detector/calculator architecture, and claims 2–3 add the lock-in-amplifier dual-reference-signal limitation while claims 4–5 recite the frequency-cycling determination logic, the practical effect is that your entire invalidity theory must be built from scratch against the full, unamended claim set.

Estoppel landscape: no § 315(e)(2) estoppel exists against anyone. Estoppel flows from an instituted IPR and a final written decision; with no trial there is none. That means every ground is available to you, including grounds a prior petitioner might have been barred from raising. Two limits remain, both statutory rather than estoppel-based:

• § 315(b) one-year bar. If you have been served with a complaint alleging infringement of 11,360,158, an IPR petition must be filed within one year of service. Complaint service date drives this deadline and should be calendared immediately. (A DJ action does not trigger § 315(b) in the same way, but a complaint does.)
• § 325(d) — the Board can deny institution where the same or substantially the same art/arguments were already before the Office during prosecution. The patent's prosecution citations (JPH11218554, JP2006078449, JP2012037278, US20060102476, US20080084219, US20120280697 (Morimoto), US20160202301 (Denso's own ground-fault determination application)) are the exact references you'd want to avoid leading with. Notably US20120280697 (Morimoto, "Vehicular insulation resistance detection apparatus") and US20160202301 (Denso, "Ground-fault determination apparatus") are the closest prior art and are already of record — a petition built on those alone invites § 325(d) denial. Lead with different art.

Pattern signals: none. No serial petitioner, no joinder, no multi-petition pattern, no defensive aggregator (no Unified Patents involvement on this patent), and no PTAB appeal behavior by Denso to analyze. The family (JP7243494B2, CN112198367B) shows Denso pursuing ordinary foreign counterpart protection, not litigating validity. This is the profile of an assertion-naive patent.

Recommended next steps

If you are an accused infringer:

1. Calendar the § 315(b) bar first. Identify the exact date you were served with a complaint pleading infringement of 11,360,158. Any IPR must be on file within one year of that date. If you are outside the window or near it, evaluate whether a DJ action or invalidity defense in the district court is your only route.
2. Build the petition from art outside the prosecution record. The seven references of record (listed above) are § 325(d) hazards. The strongest candidates are 1990s–2000s leakage/impedance-measurement art and Denso's own adjacent sensor-impedance work (e.g., US 2006/0102476, "Sensor impedance measuring apparatus…", a Denso reference already cited). The claimed advance over JP 2016-128753 is essentially the relocation of the voltage-sensing node from the coupling-capacitor/measuring-resistor junction (M1) to the measuring-resistor/current-source junction (M2) to lower the detector's voltage-withstand requirement — that is the lynchpin limitation and the natural target for § 103.
3. Expect no free roadmap. Because no panel has construed these terms, there is no prior PTAB claim construction to lean on. Budget for a from-scratch § 112/§ 103 record on terms like "complex impedance," "in a given measuring range," and the claim 4–5 computational limitations ("when the frequency of the ac current is altered, but the complex impedance is kept constant").
4. Track it, don't fear it. With no adverse PTAB ruling, the patent's validity is presumptively intact and unchallenged. Confirm whether Denso has asserted it against anyone (public district court dockets show no such case as of 2026-09-29) — if the patent has never been asserted, that itself informs your settlement leverage.

If you are monitoring this patent:

• Set a PTAB E2E / USPTO PTAB docket alert for US 11,360,158 and its family members (JP7243494B2, CN112198367B) — a first petition is likely to arrive alongside a district court complaint, so watch the litigation dockets as the leading indicator.
• Maintenance window: 4th-year fee paid 2025-12-03; next fee (7.5-year) due around 2029, adjusted expiration 2040-09-11.

Sources and verification note

• Structured PTAB proceedings block (USPTO Open Data Portal), as provided — canonical, returns zero proceedings.
• Google Patents record for US11360158B2 — no PTAB tab, no adverse legal events.
• Web verification searches (2026-09-29) across PTAB decision text, PTAB docket material, and Federal Circuit material returned no petition, institution, FWD, settlement, or appeal for US 11,360,158. Results matching 10,013,158 (Unified v. Motion Offense, IPR2020-00705) and 11,316,014 (SCI v. Greenthread, IPR2024-00263) concern different patents and are excluded.
• Confidence: high that no AIA trial proceeding is on file. Limitation: I could not directly query PTAB E2E or CourtListener RECAP in this session; a recently filed petition from the last few weeks could lag public indexing. A direct PTAB E2E party/patent search and a CourtListener docket query on "11,360,158" should be run before relying on this for a filing deadline. I have not fabricated any proceeding number to fill the gap.

I'll verify the assignment record and check for any litigation or post-issuance transfers before building the report.

Ownership & Assignment Analysis — US 11360158 B2

"Insulation resistance measuring apparatus" · Denso Corp · App. 16/923,268 · Granted 2022-06-14

Sourcing note: I do not have a live, authenticated session against the USPTO Assignment Center in this environment; the record below is reconstructed from the Google Patents legal-events ledger (authoritative text supplied), corroborated by targeted searches of the legacy USPTO assignment PDFs (legacy-assignments.uspto.gov) and Plainsite's USPTO assignment transcripts. Every entry is grounded in a cited reel/frame or is explicitly flagged as inference.

Inventors

• No co-inventors are named on the face of the patent.
• Departure pattern: Not present. Public inventor records (PatentLeaderboard) credit Mizoguchi with ~29–34 patents assigned to Denso, consistent with a career Denso engineer rather than a departing inventor — no evidence of the pre-fire-sale "all inventors leave within 12 months" tell.

Original assignee

• Entity on the issued patent: DENSO CORPORATION (Denso Corp), 1-1 Showa-cho, Kariya-city, Aichi-pref., Japan.
• Business: Tier-1 automotive supplier; the patent's own specification describes deployment in an in-vehicle motor control system (battery unit, inverter, three-phase motor) — i.e., a product line Denso actually manufactures and ships. Denso is a large publicly traded operating company (TSE: 6902).
• Product embodying the claims: The claimed insulation-resistance measuring apparatus is a Denso-designed in-vehicle leakage-detection circuit; Denso supplies such inverter/battery-monitoring hardware to OEMs (e.g., Toyota). Operating-company product, not a licensing vehicle.
• Current status: Operating. Still the assignee of record — the USPTO legal-events ledger shows a large-entity 4th-year maintenance fee paid 2025-12-03 ("PAYMENT OF MAINTENANCE FEE, 4TH YEAR, LARGE ENTITY"), and the patent is Active, adjusted expiration 2040-09-11. This is inconsistent with any transfer to a third party.

Assignment timeline

One assignment is recorded. No post-issuance assignments exist.

• 2020-07-10 (executed) / recorded 2020-07-23 — Reel 053295/0859
  • Conveyance: Assignment (Assignment of Assignors Interest)
  • Assignor: Tomomichi Mizoguchi (individual inventor)
  • Assignee: DENSO CORPORATION
  • Correspondent: Not exposed in the sources available to me for this reel. ⚠️ Inference, not a finding: Denso's contemporaneous US recordings bracket this reel — Reel 044599/0499 (recorded 2018-01-11) and Reel 055473/0508 (recorded 2021-03-03) — and both list correspondent Harness, Dickey & Pierce, P.L.C. (Bloomfield Hills / Troy, MI; contact Susan McGaw, troymailroom@hdp.com). Reel 053295 sits between them, so HDP is the likely correspondent of record, but I cannot confirm it without a direct Assignment Center query. Note that HDP also appears as correspondent on routine Denso inventor-assignment recordings and Denso air-conditioner/semiconductor recordings — i.e., it is Denso's ordinary outside prosecution/recording firm, not an NPE-side filer.
  • Context: Routine original inventor-to-employer assignment (employee invention); no consideration of a change of control.

Prior art date 2019-07-08 (JP priority JP2019-127173); US filing 2020-07-08; publication US2021/0011092 A1 (2021-01-14). Family members JP7243494B2 and CN112198367B are likewise held by Denso and show no third-party conveyances.

No further recorded assignments. Per the Assignment Center rule of thumb, this means the original assignee (Denso) still owns the patent — consistent with the 2025 maintenance-fee payment by Denso as a large entity.

Timeline diagram

timeline
    title Ownership of US 11360158
    2019 : Inventor files JP priority application
    2020 : US application filed by Denso
         : Inventor assigns rights to Denso Corp
         : Assignment recorded reel 053295 frame 0859
    2022 : US 11360158 B2 granted to Denso
    2025 : Denso pays 4th year maintenance fee

NPE / troll-pattern signals

Verdict

Insufficient data — the record contains only the original inventor-to-employer assignment.

Justification: The single recorded conveyance is Mizoguchi → DENSO CORPORATION, executed 2020-07-10 and recorded 2020-07-23 at Reel 053295/0859, a routine employee-invention assignment. There is no post-issuance transfer, no second assignee, no litigation naming this patent, and Denso remains the record owner — confirmed by its 2025-12-03 large-entity 4th-year maintenance-fee payment on the still-Active patent (expires 2040-09-11). Because the chain is a single operating-company assignment with no onward arm's-length transfer, none of the eight NPE signals can be substantiated; the "only the original assignment" case maps to Insufficient data rather than an NPE or defensive-aggregator classification.

Verify against the primary source:

• USPTO Assignment Center: https://assignmentcenter.uspto.gov/
• USPTO legacy assignment search: https://assignment.uspto.gov/patent/index.html (search patent number 11360158; confirm Reel 053295 / Frame 0859 and read the recorded correspondent field — the one field I could not independently confirm here)

Caveats on precision: (a) The correspondent of record for Reel 053295/0859 is inferred from neighboring Denso reels, not directly verified — do not treat the "Harness Dickey" attribution above as a recorded fact. (b) I likewise could not confirm whether any unrecorded license or security interest exists; such instruments would not appear in Assignment Center in any event.

I'll research US patent 11360158 and its cited prior art references. Let me search for the key references.

Let me research the remaining prior art references and gather additional details.

Prior Art Analysis — US Patent No. 11360158

1. The patent under analysis (verify identity first)

I searched for the exact number 11360158. The result is unambiguous and matches the supplied full text — no similar/nearby number was returned, so the following analysis is confined to US 11360158.

Core inventive point (claims). Claim 1 recites a coupling capacitor (one end to a DC power-supply path), a measuring resistor connected to the other end of the coupling capacitor, a current applying device connected to the measuring resistor, a detector that detects the voltage change at the junction of the current applying device and the measuring resistor (not at the coupling-capacitor/measuring-resistor node), and a calculator that computes the complex impedance of an AC circuit containing the measuring resistor, coupling capacitor, insulation resistor and grounding capacitance, and derives the insulation resistance from it. Dependent claims add: lock-in detection using two reference signals 90° apart (claims 2–3); frequency sweeping and "constant impedance ≠ Rs" identification of Rtotal (claim 4); and "imaginary part maximized → subtract Rs, double" (claim 5).

The specification's stated advance over the cited background is explicitly this junction relocation: measuring at the M2 node (current-source/measuring-resistor junction) lowers the voltage-resistance requirement of the detector and shrinks the circuit (see Summary and the "beneficial advantages" section).

2. The seven references cited on the face of US 11360158

Google Patents lists "(7)" cited references. Note the examiner/third-party flag supplied on the face: US 2006/0102476 A1, US 2008/0084219 A1 and US 2012/0280697 A1 carry the "* cited by examiner" designation; the others appear as third-party citations. Important caveat up front: I obtained full/rich text for five of the seven. For JP 2006078449 A, JP 2012037278 A, and US 2008/0084219 A1 my tool access returned only bibliographic/fragmentary data before the search limit was reached; I flag those explicitly rather than over-claiming their disclosure.

(1) JPH11218554A — "Leakage detection device for electric vehicles"

• Assignee: Matsushita Electric Industrial Co., Ltd. Priority: 1997-10-30 (JP 29916197). Publication: 1999-08-10. Family includes EP 0913697 A2/A3 and CN 1216826 A.
• Disclosure (from the EP 0913697 family text): an AC source injects a single-frequency sine signal between the vehicle body and the battery pack through a condenser (coupling capacitor) that blocks DC; a voltage detector measures the AC signal across the condenser; a current detector measures AC current; an admittance detector computes the electric-leak admittance |Y| from the AC voltage and current; a phase discriminating circuit finds the phase difference between voltage and current; a resistance-component detector computes the real part of admittance from |Y| and the phase difference; a comparator compares the resistance component with a threshold.
• Relevance: This is the closest prior art on the complex-quantity / phase concept. It derives a resistance component from an AC complex quantity (admittance real part) obtained by phase discrimination — the same physics claim 1 relies on (phase, real/imaginary parts) and that claims 2–3 implement via quadrature detection.
• Potential § 102: Possibly anticipatory of the concept of claim 1's calculator (resistance from a complex AC quantity including the coupling capacitor and the ground path) if one maps the current detector + admittance computation onto "measuring resistor + complex impedance." However, JPH11218554 senses current with a dedicated current detector and computes admittance of the leak, whereas claim 1 requires a series measuring resistor and detection of the voltage change at the current-source/resistor junction and calculation of complex impedance (not admittance). It does not disclose the claimed junction location. Best characterized as § 102/§ 103 art against the "resistance from complex AC quantity" idea and strong § 103 art in combination; unlikely by itself to anticipate claim 1 as a whole.

(2) JP2006078449A — "Electric leakage detector"

• Assignee: GS Yuasa Corporation. Priority/filing: 2004-09-13. Publication: 2006-03-23.
• Disclosure: Not retrieved in full during this search (bibliographic identification confirmed from the patent face). Title and assignee indicate a vehicle electrical-leakage detector. Treat this as a § 102/§ 103 candidate in the same technical field, but I cannot responsibly map it to specific claim language without its text.

(3) US2006/0102476 A1 — "Sensor impedance measuring apparatus for improving measurement accuracy of gas sensor"

• Assignee: Denso Corporation. Priority: JP 2004-331017 (2004-11-15) et al. Filed: 2005-11-15. Published: 2006-05-18. Inventors: Kurokawa, Hada, Niwa. (Examiner-cited.)
• Disclosure: An AC applying circuit applies an alternating voltage/current (swept positive and negative) to a gas-sensor element. A storage device — a resistor and a coupling capacitor in series — blocks DC. A voltage sampling circuit samples the voltage developed between the sensor element and the AC applying circuit, and an impedance determining circuit computes the impedance as a function of that sampled voltage (and the resistor/capacitor values). A peak-hold circuit and low-pass filtering may be used.
• Relevance: Structurally and functionally close to claim 1: AC injection through a resistor + coupling capacitor, and impedance derived from a sampled voltage at a node between the AC source network and the element under test. It demonstrates the general technique of computing impedance from a voltage sampled at the source-side node, and it uses a coupling capacitor.
• Potential § 102: Potentially relevant to claim 1's "apply AC through a coupling capacitor + resistor and compute impedance," but it is directed to a gas-sensor element (a different load than an insulation resistor returned to ground), and it does not disclose detecting the voltage at the junction of the current applying device and the measuring resistor in the claim-1 topology, nor the ground-capacitance AC circuit. More naturally § 103 material (motivation to adapt an impedance-measurement front end). Unlikely to anticipate claim 1 outright.

(4) US2008/0084219 A1 — "Impedance Measurement Using Line-to-Line Current Injection"

• Inventor: Mohamed Belkhayat. Priority/filing: 2006-10-05. Published: 2008-04-10. (Examiner-cited.)
• Disclosure: Full text not retrieved in this session; the title indicates power-system impedance measurement by line-to-line current injection (utility/grid context).
• Relevance: Different application domain (power grid rather than in-vehicle high-voltage insulation), but it is cited for the general current-injection impedance-measurement technique. Likely § 103/background; I cannot assert § 102 anticipation of any claim without the text.

(5) JP2012037278A — "Electric leakage detector"

• Assignee: Omron Automotive Electronics Co., Ltd. Priority/filing: 2010-08-04. Publication: 2012-02-23.
• Disclosure: Not retrieved in full (bibliographic identification only). Same field as the patent (vehicular electrical-leakage/insulation detection).
• Relevance: A field-relevant § 102/§ 103 candidate; specific claim mapping not possible from the data obtained.

(6) US2012/0280697 A1 — "Vehicular insulation resistance detection apparatus"

• Inventor: Naohisa Morimoto (Panasonic). Priority/filing: 2010-08-31. Published: 2012-11-08. (Family/grant: US 8,878,543 B2; EP 2613162.) (Examiner-cited.)
• Disclosure: Detects an insulation resistance between a low-voltage circuit and a high-voltage circuit. Circuit: a cyclic signal generator; a first resistor fed by the cyclic signal; a first capacitor (coupling capacitor) from the first resistor to the high-voltage circuit; a second capacitor from the first resistor to a second resistor to low-voltage ground; a diode + third-resistor clamp; a voltage detection unit that detects the voltage between low-voltage ground and the second capacitor as a detection signal; and an insulation-resistance detection unit that computes the insulation resistance from the amplitude of that detection signal. Its background explicitly describes the conventional approach of outputting an AC signal via a resistor and coupling capacitor and detecting the voltage at the connection point between the resistor and the coupling capacitor via an A/D converter.
• Relevance: This is directly on point for the problem the '158 patent addresses. Critically, the conventional arrangement it discusses samples the resistor/coupling-capacitor node — i.e., the high-voltage-exposed node — which is precisely what '158 claim 1 deliberately avoids by measuring at the current-applying-device/measuring-resistor junction instead.
• Potential § 102: Potentially relevant to claim 1 to the extent it detects a voltage in a coupling-capacitor/resistor insulation-measurement network and derives insulation resistance from signal amplitude. However, Morimoto's detection node is the coupling-capacitor-side node (and its dedicated claim topology adds a second capacitor/resistor network), not the source/resistor junction recited in claim 1, and it uses amplitude, not complex impedance. As a whole it does not anticipate claim 1; it is stronger as § 103 art showing the known coupling-capacitor/resistor insulation-measurement architecture.

(7) US2016/0202301 A1 — "Ground-fault determination apparatus"

• Assignee: Denso Corporation. Priority: JP 2015-2857 (2015-01-09). Published: 2016-07-14. Granted as US 10,120,009 B2. This is the US counterpart of the background-art document discussed in the '158 specification (JP 2016-128753).
• Disclosure: An acquisition unit applies an AC signal to the DC supply circuit through a series connection of a resistor and a capacitor and acquires a peak value of the AC signal divided by the resistance of the resistor and the insulation resistance of the DC supply circuit; a ground-fault determination unit compares the peak value to a determination threshold; an estimation unit estimates the maximum output voltage and/or the common (ground) capacitance between the DC supply circuit and the vehicle body; a setting unit sets the threshold based on the estimate.
• Relevance: This is the nearest structural antecedent: AC injection through series resistor + coupling capacitor into an in-vehicle insulated DC circuit, with an AC quantity (peak value) used to judge insulation/ground-fault, and explicit consideration of the vehicle common capacitance Cg. It is the very document the '158 patent frames itself as improving.
• Potential § 102: Potentially relevant to claim 1's "apply AC through a coupling capacitor and a resistor to a power-supply path, and derive insulation state from the resulting AC quantity," but it does not compute a complex impedance (only a real peak value), does not recite the source/measuring-resistor junction detection, and does not derive the insulation resistance value as a complex-impedance function. Not an anticipating reference; strong § 103 art and the principal background reference.

3. Consolidated anticipation matrix (technical analyst's view)

Because § 102 anticipation requires a single reference disclosing every element of the claim as arranged, and § 103 requires the differences to be obvious, my assessment is:

Overall: No single cited reference appears to disclose all of claim 1 — in particular the combination of (i) detection at the current-applying-device/measuring-resistor junction (the '158 patent's stated point of novelty) and (ii) derivation of the insulation resistance from a complex impedance of an AC circuit that includes the coupling capacitor and the ground capacitance. The cited art is best deployed as § 103 combinations: US2016/0202301 (or US2012/0280697) as the base insulation-measurement architecture, JPH11218554 for the complex/phase → resistance-component step, and US2006/0102476 for computing impedance from a voltage sampled at the injection-network node.

4. Explicit limitations / confidence

• High confidence: identification of US 11360158, its bibliographic data, its full five-claim set, and the disclosures of JPH11218554 (via EP 0913697 family), US2006/0102476, US2012/0280697 and US2016/0202301 / US 10,120,009.
• Lower confidence: full technical disclosure and claim mapping for JP2006078449A, JP2012037278A, and US2008/0084219A1 — my searches for these returned only identifying data before tool limits were hit. Their § 102/§ 103 entries above are therefore provisional and should be completed against their full texts.
• Per operating rules, I did not auto-correct any identifier. All numbers (11360158, JPH11218554A, JP2006078449A, US20060102476A1, US20080084219A1, JP2012037278A, US20120280697A1, US20160202301A1) are reproduced exactly as cited/located. Anticipation statements are technical assessments, not legal conclusions.

I'll analyze the obviousness of US 11,360,158 using the prior art listed on the patent page. Let me first verify the content of the key references.

Let me verify a few more of the listed references to ground the analysis.

Obviousness Analysis — U.S. Patent No. 11,360,158 B2

Patent: US 11,360,158 B2 ("Insulation resistance measuring apparatus"), Denso Corp., inventor Tomomichi Mizoguchi, filed 2020‑07‑08, priority JP 2019‑127173 (2019‑07‑08), granted 2022‑06‑14. Source: https://patents.google.com/patent/US11360158/en

Note on dates. The effective priority date is 2019‑07‑08. Every reference I rely on below has a publication date before that date, so all qualify as prior art under AIA § 102(a)(1)/(a)(2): US 2016/0202301 A1 (pub. 2016‑07‑14), US 2012/0280697 A1 (pub. 2012‑11‑08), US 2006/0102476 A1 (pub. 2006‑05‑18), US 2008/0084219 A1 (pub. 2008‑04‑10), JP H11‑218554 A (pub. 1999‑08‑10), JP 2006‑078449 A (pub. 2006‑03‑23), JP 2012‑037278 A (pub. 2012‑02‑23), US 10,855,095 B2 (pub. 2020‑12‑01, from US 2019/0115762 A1, pub. 2019‑04‑18, filed 2017‑10‑12). The "Families Citing this family" entries (e.g., JP 7540403 B2, KR 20240011935 A) are later documents and are not prior art — I exclude them.

I interpret all identifiers literally as they appear in the patent page. Where I have not verified a reference's figure-level detail, I say so.

1. Legal framework and level of ordinary skill

Obviousness is judged under Graham v. John Deere (scope/content of prior art; differences; PHOSITA level; secondary considerations), with the KSR rationales available: combining known elements, adapting a known technique, obvious substitution, and design incentives/predictable results. The person of ordinary skill here is an engineer with ~3–5 years' experience in vehicle high‑voltage insulation monitoring and AC impedance measurement who is familiar with (i) resistor/coupling‑capacitor leakage detection, (ii) lock‑in/quadrature demodulation, and (iii) Nyquist/complex‑impedance characterization. The inventions are in one recognized field: detecting insulation resistance (leakage/ground fault) between a vehicle high‑voltage DC supply path and the vehicle body through a series resistor and coupling capacitor.

2. The relevant prior art

D1 — US 2016/0202301 A1 (Denso), "Ground‑fault determination apparatus." https://patents.google.com/patent/US20160202301A1/en — This is the US counterpart of the JP 2016‑128753 publication that US 11,360,158 itself cites as background art, so it is admitted prior art. Its abstract recites: "an acquisition unit that applies an AC signal to the DC supply circuit through a series connection of a resistor and a capacitor to acquire a peak value of the AC signal divided by a resistance of the resistor and an insulation resistance of the DC supply circuit"; a comparison of that peak to a threshold; and estimation of the "common capacitance between the DC supply circuit and a vehicle body," with the threshold set as a function of the maximum output voltage and/or the common capacitance. It discloses the exact power‑system environment claimed (DC power source, converter 14, inverter 16, MG 18, SMR/CHGR relays, insulated from vehicle body).

D2 — US 2012/0280697 A1 (Morimoto / Panasonic; granted US 8,878,543), "Vehicular insulation resistance detection apparatus." https://patents.google.com/patent/US20120280697A1/en — Self‑resistor R1 fed by a "cyclic signal generating unit," a coupling capacitor C1 to the high‑voltage circuit, a voltage detection unit, and an "insulation resistance detection unit that detects a resistance value of the insulation resistance based on an amplitude of the detection signal." Critically, D2 expressly recognizes the same problem the '158 patent identifies: at the moment of a ground fault, the potential on the insulation‑detection‑circuit side of the coupling capacitor "undergoes an instantaneous change … by several hundreds volts," while "the input voltage range of an A/D converter is typically about 5 V to 10 V," rendering the signal amplitude undetectable until the coupling capacitor re‑charges.

D3 — US 2006/0102476 A1 (Denso / Niwa et al.), "Sensor impedance measuring apparatus…." https://patents.google.com/patent/US20060102476 — An AC applying circuit applies AC through a divider resistor (24) and coupling capacitor (25); a "voltage sampling circuit samples a voltage developed between the sensor element and the ac applying circuit"; an impedance determining circuit determines impedance from the sampled voltage. D3 also shows (its FIG. 5(a)) a conventional impedance system that samples Vx at the junction between the op‑amp/current source (51) and the current‑measuring resistor (52), and compares the two sensing topologies for accuracy/SNR.

D4 — US 2008/0084219 A1 (Belkhayat et al.; granted US 7,746,084), "Impedance measurement using line‑to‑line current injection." https://patents.google.com/patent/US20080084219 — A current‑injection device injects current at a selected frequency; line voltages and phase currents are obtained over a swept frequency range and transformed "to a q‑d synchronous reference frame" to calculate impedance/admittance. This is express quadrature (d and q are 90° apart) decomposition of an injected‑current impedance measurement.

Other listed art. JP H11‑218554 A (Matsushita) and JP 2012‑037278 A (Omron) are vehicle leakage detectors; JP 2006‑078449 A (GS Yuasa) is an "Electric leakage detector." US 10,855,095 B2 (Infineon) computes the complex impedance of a battery as Z(f)=V_AC(f)/I_AC(f) with explicit Real{ Z } and Im{ Z } parts (http://patentimages.storage.googleapis.com/70/18/8d/f58ca9c0c83122/US10855095.pdf). CN 101666861 B (multi‑frequency‑point AC discharge battery detection) and US 8,598,897 B2 (Maxim, isolation monitoring) round out the complex‑impedance/sweep teaching.

3. Claim 1 — primitively obvious over D1 in view of D2 and D4 (with D3)

Claim 1 requires: (a) coupling capacitor → power supply path; (b) measuring resistor at the capacitor's second end; (c) a current‑applying device connected to the measuring resistor; (d) a detector that detects a voltage change at the junction of the current‑applying device and the measuring resistor; and (e) a calculator that computes a complex impedance of an AC circuit including the measuring resistor, coupling capacitor, insulation resistor, and grounding capacitance, and determines the insulation resistance from it.

Motivation to combine.

• Same field, same problem, express recognition. D1, D2, D3 and the '158 patent all concern deriving an insulation resistance between a vehicle high‑voltage path and the body via a resistor + coupling capacitor. D2 states verbatim the problem the '158 patent recites in its background ("several hundreds volts" at the capacitor‑side node exceeding the A/D input range). A PHOSITA seeking to reduce the required voltage rating of the detector in D1's system would be squarely led by D2 to re‑situate/condition the sensing node away from the coupling‑capacitor side.
• Known, predictable way to do it. D2 shows that reducing the voltage seen by the detection circuitry is achievable by tapping the sensing network on the low‑voltage side; the '158 patent's own asserted benefit ("a decrease in required voltage resistance of the detector by use of the measuring resistor") is the predictable consequence of placing the sense point behind a series measuring resistor — a result‑effective variable (voltage division) the artisan would have expected. KSR: predictable result from a known technique.
• D3 supplies the missing node. D3's conventional impedance system samples the voltage at the junction between the drive source and the current/measuring resistor — exactly the "junction of the current‑applying device and the measuring resistor." D3 therefore supplies element (d) as a known, usable sensing topology. That D3 criticizes that topology on accuracy grounds is a teach‑away argument worth raising, but D3 does not teach away from the node per se; it criticizes using the signal as the impedance metric without correction, and moreover it discloses the alternative of tapping the resistor network (FIG. 11/12).
• Complex impedance is the obvious refinement of D1. D1 must estimate the common capacitance and set thresholds because the peak amplitude is corrupted by the variable ground capacitance Cp/Cn. D4 and US 10,855,095 teach computing the vector impedance (magnitude and phase, or Re/Im) from an injected AC current, which yields Rg directly with the grounding capacitance represented in the model rather than as an error term. D1 itself thus supplies the reason (variable common capacitance) and D4 supplies the means (complex‑impedance computation), giving strong motivation.

Conclusion (claim 1): Obvious under § 103 as D1 + D2 + D4, optionally with D3 for element (d). The only limitation without literal disclosure in the primary references is the specific sense node; it is rendered obvious by D2's problem statement plus D3's known sampling node.

4. Claim 2 — obvious (D4 + the known lock‑in/quadrature technique), with D1/D2/D3

Claim 2 recites a detector that forms (i) a first product of a first reference signal produced synchronously with the AC current and the voltage change and (ii) a second product of a second reference signal (out of phase) and the voltage change, the calculator then using both products for the complex impedance. That is textbook synchronous (lock‑in) detection.

• D4 expressly transforms measurements "to a q‑d synchronous reference frame," i.e., extracts in‑phase (d) and quadrature (q) components of the injected‑current response and computes impedance from them. Multiplying the response by a synchronous reference and its phase‑shifted copy and low‑pass filtering to obtain the real and imaginary parts is precisely the q/d decomposition of D4 and the Re/Im characterization of US 10,855,095. D3's synchronous sampling of the AC response is a species of the same principle.
• The '158 specification itself describes these as standard building blocks (multipliers 55/58, integrators 56/59, low‑pass filters 57/60) — "familiar elements according to known methods," the KSR paradigm. No unexpected result is asserted for the quadrature structure per se; the asserted benefit (noise rejection, simplification of the analog filter) is generic and expected.

Conclusion (claim 2): Obvious over D1+D2+D4 (or D3+D4), the quadrature product/demodulation feature being a well‑known impedance‑measurement technique.

5. Claim 3 — obvious

Claim 3 simply requires the first reference signal to be 90° out of phase with the second. This is inherent in quadrature detection and is the definition of the d‑q decomposition in D4 (the quadrature axis is 90° from the direct axis). A 90° phase‑shift circuit (the patent's element 61) is a conventional component. Obviousness follows a fortiori from claim 2; this claim adds only a mathematically inherent relationship.

6. Claim 4 — algorithm claim; weakest, but likely obvious as an application of known frequency‑swept impedance measurement

Claim 4 requires cyclically altering the AC frequency within a measuring range and, when the complex impedance stays constant (plateau) while its real part/absolute value is not equal to the measuring resistor, deriving Rg from that real part/absolute value. This is nothing more than detecting the frequency bands where the grounding capacitance is effectively an open/short so that |Z| equals Rs or Rs+Rg, and selecting the higher plateau.

• D4 injects at a selected frequency and over a swept range and computes impedance at each frequency to characterize the source/load; US 8,598,897 B2 (isolation monitoring) and CN 101666861 B (multi‑frequency AC) likewise sweep frequency for impedance characterization. Once the artisan computes Z(f), identifying the constant‑|Z| regions is a direct reading of the data.
• The correspondence "plateau ⇒ Rs or Rs+Rg" is a mathematical property of the series/parallel R‑C model, not a physical discovery. KSR and its progeny treat automation of a known mathematical relationship/mental process with a generic computer as obvious.

Caveat (stated candidly): I did not find, among the references listed on this page, an express teaching of using the plateau regions to select between Rs and Rs+Rg. An examiner or litigant could argue claim 4's specific discriminating step is not squarely disclosed. The strongest obviousness position for claim 4 is: (i) D4's frequency‑swept impedance computation + (ii) D1's express recognition that the ground/common capacitance (not the insulation resistance) governs the frequency behavior, giving the artisan reason to look for the capacitance‑independent plateaus.

7. Claim 5 — algorithm claim (semicircle maximum) ; moderately obvious

Claim 5 requires cyclically altering frequency and subtracting the measuring resistor from the real part at which the imaginary part is maximized, then doubling the result. This is the classic Nyquist semicircle: the diameter from Rs (Im = 0) to Rs+Rg (Im = 0), with the apex (maximum Im) occurring at the midpoint, where Re = Rs + Rg/2; hence Rg = 2·(Re_apex − Rs).

• This is standard electrochemical‑impedance/Nyquist analysis. D4 produces the impedance magnitude/phase across a swept frequency (its FIGs. 6a–7b plot impedance magnitude and phase vs. frequency), which is the data from which such a semicircle is drawn; US 10,855,095 B2 explicitly separates Re{ Z(f) } and Im{ Z(f) } as a function of frequency.
• As with claim 4, the operation is an application of a known mathematical characterization to data the prior art already generates, and the patent's own rationale is stated in purely mathematical terms ("the imaginary part Im_Z … is maximized at the intermediate point P3 …, subtracting the resistance value of the measuring resistor Rs … and doubling it").

Caveat: the linkage of the "maximum imaginary part" criterion to determining the insulation resistance of a vehicle power path is not, to my knowledge, expressly disclosed in any of the seven examiner‑cited references; it is a general EIS technique. The motivation argument rests on: (i) D4/US 10,855,095 teach generating Re/Im vs frequency; (ii) the mathematical relationship is inherent; and (iii) the motivation for using it (the patent's stated reason — to permit a smaller coupling capacitor Cs, since the second plateau T2 disappears) is a design option within the skill of the art. This is a weaker obviousness position than claims 1–3.

8. Secondary considerations and counter‑arguments

• Asserted advantage = expected result. The '158 patent's sole stated advantage is that measuring at the M2 junction (behind the measuring resistor) "enables the circuit to be reduced in size" by lowering the detector's voltage rating. This is exactly the result D2 says is needed and the result a PHOSITA predicts from voltage division behind a series resistor. Under KSR, a predictable, result‑effective variation weighs toward obviousness. The record shows no comparative data establishing an unexpected degree of size/voltage reduction.
• Common assignee. D1 and D3 are both Denso (the '158 patent's assignee) and D2 is in the same vehicle‑insulation field. Common ownership is not required for combination, but it strengthens the "reason to combine" narrative (shared design context; D1 → D2 → D3 are in the same technical lineage).
• Possible counterargument 1 (teach‑away). D3 criticizes the source‑side/current‑sensing node for accuracy and SNR, which a patentee could frame as teaching away from element (d). The rebuttal is that D3's criticism concerns using that node's raw signal as the impedance metric without correction, and D3's own disclosure shows the artisan alternative arrangements of the resistor network; the '158 patent also uses a bandpass filter and quadrature correction, mitigating D3's concern.
• Possible counterargument 2 (§ 101/§ 112). Claims 4 and 5 recite algorithms that could invite eligibility/enablement challenges; that is outside § 103 but is relevant to overall claim strength and to how much weight the plateau/maximum criteria carry.
• What would strengthen the challenge / what I cannot confirm. I have not verified D1's exact sense node from its figures (the '158 background characterizes the JP 2016‑128753 family as sensing at the measuring resistor's battery‑side junction, which I rely on). I could not retrieve substantive content for JP 2006‑078449 A, JP H11‑218554 A, or JP 2012‑037278 A within this session, so I have not relied on them for specific limitations. If they disclose quadrature detection or plateau/maximum‑based insulation‑resistance extraction, claims 2–5 would be strengthened.

9. Bottom line

Claims 1–3 are the most vulnerable to a § 103 combination of D1 in view of D2 and D4 (with D3 supplying the sense‑node topology). Claims 4–5 are narrower algorithm claims whose obviousness depends on treating the plateau and maximum‑imaginary‑part criteria as applications of known impedance‑characterization mathematics to data the prior art already generates.

Caveat on completeness: this analysis is based on the reference set listed on the Google Patents page for US 11,360,158 as retrieved 2026‑09‑24, and on the reference texts I was able to retrieve; where a reference's full text was unavailable (the JP publications, and figure‑level detail of D1), I have flagged the limitation rather than assumed disclosure.