US 10527457

I'll search for the specific patent number and any associated litigation/docket activity.

Let me search for any litigation and the full claim set.

Let me get the full independent claim text from the patent's claims.

Technical Patent Analysis — US 10,527,457

Important search notice up front: I searched for this patent number paired with litigation, CAFC 2026 docket, IPR, and Federal Circuit terms. No CAFC 2026 docket entry, district court case, or PTAB proceeding involving US 10,527,457 was found in the search results. The litigation-flavored results returned were about unrelated patents (e.g., Wilus v. Samsung, Netlist, Sarepta/NS Pharma). I cannot confirm the absence of such proceedings with authority — only that my searches surfaced none. Treat the "no litigation found" statement as a search limitation, not a verified fact.

Also note: the authoritative patent text supplied to me is truncated before the claims (it cuts off mid-sentence in the FIG. 18 description, ending "This may then be f—"). I therefore rely on Google Patents / Justia claim text for the claim summary, and I flag below where the grant-numbering is inferred rather than quoted directly.

1. Bibliographic data (from the authoritative Google Patents record)

2. Abstract

"Inductance values are measured though the use of a charge transfer based measurement system. During a first phase, a target inductor is connected to an energy source to allow current through an inductor to increase. In a second phase, the inductor is disconnected from the energy source, to allow the current to decrease, and to facilitate transfer of charge to a capacitor. The phases may be repeated, and a count is kept of the number of repetitions."

3. Plain-language overview

Core idea. Instead of measuring inductance with an LC oscillator or a dedicated inductance-to-digital converter, the patent applies the charge-transfer measurement technique (previously used for capacitive sensing, and reflected in the incorporated Azoteq patents US 8,395,395 and US 8,659,306) to inductors. The inductor is energized for a fixed "first phase," then allowed to free-wheel through a diode/switch in a "second phase," and the decaying current is mirrored and dumped into an accumulation capacitor. Repeating the two phases builds a charge count; when the count (or the capacitor voltage) reaches a threshold, that metric is proportional to the inductance.

Application breadth. The specification extends the same concept to: mutual inductance between a transmitter/receiver coil pair; on-chip inductors; metal-wheel rotation speed and direction sensing (FIGS. 3–6, 15); tactile/dome switches sealed behind rigid or liquid-/gas-proof covers using magnetism or inductance (FIGS. 7–11); driver-coil/receiver-coil user interfaces, rotary selector switches and stylus tracking arrays (FIGS. 12–16, 19–22); and combined inductance + capacitance sensing on the same structure — including SAR protection, headphone on-head detection, and counterfeit banknote metal-composition screening (FIGS. 17–18).

4. Independent claims (plain language)

The granted patent appears to contain two independent claims — claim 1 (self-inductance) and claim 10 (mutual-inductance) — out of 20 total claims, based on the claim text retrievable from Justia/Google Patents. Claim 16/17/19 text was truncated in my search results, so I cannot rule out a third independent claim.

Claim 1 — Integrated circuit for measuring self-inductance

(with verbatim correspondence to claim 23 of the pre-grant publication, since the granted claim-1 text was not fully retrievable): An IC with an energy-transfer measurement circuit containing first and second controllable switches, at least one current mirror, and an accumulation capacitor. The inductance is connected through the first switch to an energy source in a first phase so current ramps in the inductor; then a second phase opens the first switch and closes the second switch so current in the inductance continues uninterrupted (free-wheels) — and current flows through the inductance into the input of the current mirror during both phases. The mirror's output transfers energy to the accumulation capacitor; the IC registers a count of repetitions of the first and second phases, and that count (or the capacitor's voltage) is used as a metric proportional to the self-inductance.

Claim 10 — Integrated circuit for measuring mutual-inductance

An IC with an energy-transfer measurement circuit including a wave generator, at least one current mirror structure, and an accumulation capacitor. The wave generator energizes a transmitter inductor; the receiver inductor carries current due to the mutual inductance, which flows through the current mirror input; the mirror output charges the accumulation capacitor; and a registered count of energy-transfer repetitions (or the accumulated capacitor voltage) is a metric proportional to the mutual inductance.

Notable dependent-claim themes (as retrievable)

• Claim 11: mutual-inductance embodiment implemented with first/second controllable switches and an energy source (the two-phase scheme applied to a transmitter/receiver pair).
• Claim 12: transmitter and receiver inductors located within the IC package.
• Claim 13: a voltage source in series with the receiver inductor, of a magnitude just below the current-mirror input-diode forward-bias voltage and of opposing polarity — the "bias to just below conduction" trick to enable measurement of very small mutual inductance.
• Claim 14: transmitter/receiver inductors used to sense rotation of a (partly or wholly) metal wheel.
• Claim 15: the same energy-transfer circuit also used for capacitance measurements, with the coils doubling as transmitter/receiver capacitive electrodes.
• Claim 18: SAR-protection circuitry located within the same IC.
• Claim 20: dial-switch embodiment with a circular array of transmitter inductors around a central receiver inductor, and two coupling members (one high-permeability, one conductive) arranged co-linear, where the IC requires both an increase in coupling to one inductor and a corresponding decrease at another before annunciating a dial position (a robustness/anti-false-trigger feature).
• Claim 5 (dependent): product with RF transmitter, where mutual-inductance + capacitance measurements feed SAR protection logic to decide when to reduce RF transmit level.
• Claim 4 (dependent): capacitance measurement used for proximity detection that wakes the IC into a higher-power mode, in which the mutual-inductance measurement is then performed.

5. Key technical features relied on in prosecution/specification

1. Anti-phase, dead-time-free switching of the two switches (e.g., at ~500 kHz) so the free-wheel path is always available.
2. Third switch (S3) at the current-mirror output, closed with S2, so charge is transferred to the accumulation capacitor only during current decay — noted in the specification as optional.
3. Current-mirror scaling of the free-wheel current, allowing a much smaller accumulation capacitor than if the capacitor were in series with the free-wheeling diode.
4. Resonant boosting (FIG. 2G): series L–C driven at resonance to raise receiver-coil voltage high enough to forward-bias the mirror input diode when mutual coupling is weak.
5. Parasitic L/C compensation using current mirrors, expressly incorporated by reference from US 8,395,395 and US 8,659,306.
6. Long-Term Averaging (LTA) of charge-transfer counts with digital filtering to compensate temperature/aging drift.
7. Selectable "see metal" vs. "see through metal" modes by tuning charge-transfer frequency relative to the metal skin depth.

6. Uncertainty and caveats

• Claims text: I could not retrieve the granted claim 1 verbatim; the wording given above is the substantive equivalent of claim 23 of the pre-grant publication (US 2018/0128650 A1). Because the pre-grant and granted claims are renumbered, I label this as a strong inference rather than a direct quote.
• Independent-claim count: Claim text for granted claims 16, 17 and 19 was truncated in my sources. I know claim 20 depends from claim 10 and claim 18 depends from claim 17, but I cannot confirm whether claims 16/17/19 are independent. Do not treat "only two independent claims" as certain.
• Assignee chain: Two different entities appear — Azoteq (Pty) Ltd (original/face assignee) and Azoteq Holdings Limited (current, per the recorded assignments of Oct. 19, 2021 and Jan. 12, 2022). Google's own disclaimer states its assignee list "may be inaccurate."
• Litigation/CAFC: No 2026 CAFC docket activity, IPR, or district-court assertion for US 10,527,457 was found. This is a null search result, not evidence that none exists. USPTO PatentCenter / PACER / CourtListener would need to be queried directly to confirm.
• Numbering discipline: All identifiers above are reproduced literally as found; the patent number is 10,527,457 and the application number is 15/554,181 throughout — no correction has been applied.
• Date note: My operating date is 2026-09-29, whereas the task states April 26, 2026. This does not affect the bibliographic facts above, which are fixed as of the Jan. 7, 2020 grant.

Sources: Google Patents US10527457B2 (authoritative text supplied); Google Patents/USPTO PDF front-page data (patentimages.storage.googleapis.com .../US10527457.pdf); Justia Patents 10527457 and publication 20180128650 (claims); patents-review.com and FreePatentsOnline for the publication text.

I'll search litigation databases and court sources for this specific patent number.

Initial searches only returned the patent itself and unrelated hits. Let me search litigation-specific sources and Azoteq enforcement activity.

I'll verify the structured block's "no proceedings" result against live sources before drafting.

Let me check for any Azoteq-related PTAB activity and any litigation that might have spawned an IPR.

Verification note before the findings

I sourced the proceedings list from the structured "PTAB proceedings on file" block, which reports the USPTO Open Data Portal (ODP) returning no AIA trial proceedings for US 10,527,457 as of the most recent ingest. I then ran independent web searches to look for anything the ODP hasn't indexed (recently filed petitions, older proceedings, CAFC appeals). Those searches surfaced nothing — no IPR/PGR/CBM case numbers, no Final Written Decisions, no appeal opinions. I did not find proceedings that the structured data missed, so there is nothing to flag.

I am not going to invent proceeding numbers to fill the template. What follows is the accurate record plus the procedural-eligibility analysis that matters to a defendant.

Proceedings overview

As of 2026-09-29, US 10,527,457 has zero AIA trial proceedings on file — 0 active, 0 with claims invalidated, 0 with claims sustained, 0 settled, 0 institution denials — and no Federal Circuit appeal of any PTAB decision, because no PTAB decision exists. The bottom-line defensive posture: the patent stands completely un-narrowed and fully intact, with the entire claim set untested and no § 315(e)(2) estoppel anywhere in the ecosystem — a defendant must build its own invalidity case from scratch against a patent whose claims have never been construed by the Board, but equally has the full universe of § 102/§ 103 patents-and-printed-publications art available with no prior petitioner having locked up grounds.

No proceedings on file — what was checked and what it means

Rather than fabricate entries, here is the verification record:

No entry under any of the template headings (type, judge panel, institution decision, FWD, settlement, appeal) can be completed, because none of those events has occurred.

Caveats I want on the record:

• ODP ingest lags. A petition filed in the last several weeks may not appear in the structured data.
• My search coverage was not exhaustive — I could not verify the absence of proceedings against PTAB E2E directly, and my litigation search was cut short. The negative finding is strong but not absolute.
• The structured block is the canonical source per the operating rules, and it says "no PTAB activity on file." I am treating that as the finding of record.

Trial-eligibility posture of the patent (this is the part that actually helps a defendant):

• IPR (§ 311): still available today, indefinitely. No statutory deadline runs from patent grant. The only timing constraint is the petitioner-specific § 315(b) one-year bar, which starts the day you are served with a complaint alleging infringement. If you have not yet been served, your IPR window is wide open; if you have been served, count the days.
• PGR (§ 321): closed. The patent granted 2020-01-07; the § 321(c) nine-month window expired 2020-10-07. Any § 112 written-description/enablement attack that only a PGR could have carried is now unavailable in an AIA trial.
• CBM: unavailable. The AIA § 18 transitional program sunset for petitions filed on or after 2020-09-16, and in any event this patent (inductance sensing and charge-transfer measurement circuitry) is not a "covered business method" patent directed to a financial product or service.
• Practical consequence: your only AIA-trial vehicle is an IPR, and § 311(b) confines you to patents and printed publications as the basis for § 102/§ 103 grounds. System/prior-use/product art must go to the district court (or the ITC).

Strategic summary

Claim status — everything is untested and everything survives. There are no canceled claims, no substitute claims, no certificate issuing under § 318(b). Every claim that issued on 2020-01-07 remains in force as written; the patent's adjusted expiration is 2036-10-08 and its status is active. When you build an invalidity case, you cannot point to a claim already held unpatentable. Whatever independent claims the patent carries — the self-inductance charge-transfer apparatus and method claims exemplified by FIGS. 1 and 2A–2G, and the mutual-inductance/driver-receiver variants — are all live. Do not assume any of them are weak merely because nobody has attacked them; conversely, do not assume any of them are strong for the same reason. The claims have also never been construed by the Board, so there is no Phillips-based PTAB construction to borrow for a § 112 theory or a claim-differentiation argument.

Estoppel landscape — a clean slate. Because no IPR was ever instituted, no petitioner is barred under § 315(e)(2), and there is no privity chain to worry about. Practically, that cuts both ways for a defendant today:

• You are free to raise any § 102/§ 103 ground, including art that would have been "reasonably available" to a hypothetical earlier petitioner — the classic trap (a prior petitioner's estoppel foreclosing your best reference) simply does not exist here.
• You gain nothing from anyone else's work product. There is no petition, no institution decision, no FWD, and no POP or Precedential Opinion Panel guidance on this patent to mine for admitted claim scope, expert admissions, or a stipulated construction.
• If you are the first petitioner, you own the § 315(e)(2) estoppel risk entirely: whatever you raise or reasonably could have raised in the IPR is gone from your district-court invalidity case after FWD. On this patent, with no prior art record to lean on, that argues for putting your complete best art into the petition — there is no second bite and no prior petitioner to absorb the loss.

Pattern signals — none. There is no repeat-petitioner pattern, no serial-IPR campaign, no patent-owner appeal practice, and no evidence of a defensive aggregator (e.g., Unified Patents, RPX) in the chain. I found no litigation hits either, though that search was limited. The ownership history on the face of the record is ordinary corporate housekeeping: Azoteq (Pty) Ltd as original assignee (2016-02-26 filing), assignments recorded 2019-02-21 and 2021-10-19, and Azoteq Holdings Limited as current assignee. Nothing about that chain suggests the patent has been pushed into an assertion campaign that would attract IPR filings — which is consistent with, and partly explains, the zero-proceeding result.

Recommended next steps

This is a "no PTAB activity" case, and I will say so plainly: there is no Final Written Decision to link to, no claim to quote as canceled, and no disposition to rely on. The absence of proceedings is itself the signal — well-asserted patents in active campaigns reliably attract IPR petitions, and this one has attracted none through 2026-09-29.

1. Confirm the negative before you rely on it. Re-run the search directly at PTAB E2E / PTAB Decisions (https://ptab.uspto.gov/#/search) and via the USPTO PTAB API (https://developer.uspto.gov/ptab-api/swagger-ui.html), searching by patent number 10,527,457 and by "Azoteq." ODP lag is real, and a very recent petition would not be in the structured data. Check Prosecution and assignment history at Patent Center: https://patentcenter.uspto.gov/applications/15554181.

2. If you have been served with a complaint, calendar the § 315(b) deadline immediately. One year from service. That is your only hard date right now — there is no institution deadline, no oral hearing, and no FWD due date to track, because no trial exists.

3. If you intend to file, budget for a full-scope petition. With no earlier petition to inherit arguments from, and PGR/CBM foreclosed, your IPR is your only shot at AIA-trial invalidity. Build the § 102/§ 103 grounds from patents and printed publications only (§ 311(b)), and consider that the patent's own specification cites U.S. Pat. Nos. 8,395,395 and 8,659,306 (both incorporated by reference for charge-transfer parasitic-compensation techniques) — those are worth evaluating as art, subject to whether they qualify as prior art and the effect of the incorporation.

4. Litigation collateral worth searching. I was unable to complete a docket sweep. Check CourtListener (https://www.courtlistener.com/?q=%22Azoteq%22) and PACER for any Azoteq infringement actions involving this family, and check the ITC for § 337 investigations. If litigation exists, run the Fintiv factors before filing — the Board has discretion to deny institution where a parallel district court case is advanced, and on an untested patent that discretion is a real risk.

5. Do not over-read the clean record. "No IPRs" is not "no invalidity." It may reflect a non-practicing-owner posture, a low-value assertion, cost constraints on would-be petitioners, or simply that no one has yet had the one-year trigger. Treat it as an open field, not as a validation of the claims.

One correction to a natural assumption: the "159273..."/"10527457" cross-references that appear in some search results (e.g., Google Patents pages for unrelated patents listing US 10,527,457 in their citation tables) are citation-table noise — they are not PTAB records and should not be read as evidence of proceedings.

I'll start by pulling the primary-source record and cross-referencing the assignees/inventors against litigation and NPE directories.

Let me check for litigation/assertion activity and the identity of the two Azoteq entities.

Critical lead: a prior Azoteq portfolio went to Global Touch Solutions (an NPE). Let me check whether '457 itself has been asserted, and the status of the Azoteq entities.

US 10,527,457 B2 — "Inductance Sensing" — Ownership & NPE Reconstruction

Bottom line up front: I could not verify the full Assignment Center record for this patent. What I could verify is that the chain is short, entirely intra-group, and shows no third-party transfer. Critically, the reel/frame and correspondent fields for two of the three links were not retrievable from the sources I could reach within my search budget, so I am flagging those as gaps rather than filling them in. Do not treat the reel/frame citations below as complete.

Inventors

Both inventors are listed on the face of the patent as residing in Paarl, South Africa, and both are named against the Azoteq correspondence address (109 Main Street, Paarl) on the related Azoteq filing WO 2015/131209. Bruwer is identified as Azoteq's founder/CEO/President (CB Insights company profile, https://www.cbinsights.com/compare/azoteq-vs-tashan-tech).

Unusual-pattern check — inventor departure:

• Not present. Bruwer is the founder and, per the sources retrieved, remains CEO/President of the assignee. There is no evidence of inventors departing the original assignee within 12 months of filing, and no evidence of a portfolio fire-sale.
• One timing oddity worth noting: the inventor→company assignment was not recorded until 2019-02-21 — roughly three years after the 2016-02-26 filing and about ten months before the 2020-01-07 grant. The execution date was not retrieved, so I cannot tell whether the document was executed at filing and merely recorded late (routine for foreign applicants preparing for U.S. issuance) or executed late. I am not drawing a conclusion from this alone.

Original assignee

Azoteq (Pty) Ltd, Paarl, South Africa (also styled in the record as "AZOTEQ (PTY) LTD" and "Azoteq Pty Ltd").

• Line of business: Fabless semiconductor designer of sensor-fusion ICs — capacitive (ProxSense), inductive, Hall-effect, and ambient-light sensing integrated into single chips. Founded 1998, headquartered in Paarl, South Africa.
• Did they ship a product embodying the claims? Likely yes, but not independently verified for this patent. Azoteq publicly markets sensing ICs (datasheets hosted at azoteq.com, e.g. the IQS319 datasheet at https://www.azoteq.com/images/stories/pdf/IQS319_Datasheet_v1.9.pdf), and it cites its own technical white paper "Inductive Versus Capacitive Position Sensors" on the patent's literature record. I did not confirm a specific part number that practices the '457 claims. Treat "ships an embodying product" as probable, unverified.
• Current status: Operating, privately held (no SEC filings; investors identified in third-party profiles include FI Capital and CMBC Capital Holdings). Not dissolved, not in bankruptcy. The U.S. patent is now held by the group holding entity Azoteq Holdings Ltd (current assignee of record). I could not determine Azoteq Holdings Ltd's jurisdiction of incorporation from the records retrieved — the address-correction issue discussed below is itself a hint that the recorded address was unreliable.

Important family-level context

Earlier Bruwer/Azoteq patents — US 7,329,970; US 7,265,494; US 7,498,749 (Bruwer-invented) — were transferred by Azoteq (Pty) Ltd to Global Touch Solutions, LLC, which then sued VIZIO, Inc. in the Eastern District of Virginia on 2014-07-09 asserting them (via iKnow/STPI report, https://iknow.stpi.niar.org.tw/post/Read.aspx?PostID=9891).

This is a material risk indicator for the family, not a finding for this patent: it shows Azoteq has previously moved Bruwer patents into an asserting vehicle. However, US 10,527,457 has a 2015 priority date — it postdates the GTS transfers — and the record shows it has not left the Azoteq group.

Assignment timeline

Caveat first: The Assignment Center record was not directly retrievable during this run. The entries below are reconstructed from the legal-events record, which supplies reel/frame for only one link. Reel/frame and correspondent are marked "not retrieved" where I could not confirm them. I have not filled these in by inference.

• executed date not retrieved / recorded 2019-02-21 — Reel not retrieved

  • Conveyance: Assignment of assignors' interest (inventor-to-company)
  • Assignor: Frederick Johannes Bruwer; Douw Gerbrandt Van Der Merwe
  • Assignee: AZOTEQ (PTY) LTD
  • Correspondent: not retrieved. Possible lead, unverified: a PTAB petition record for a related Bruwer/Azoteq patent ("Intelligent User Interface Including a Touch Sensor Device", filed 08/27/2010) references a Power of Attorney with "patent practitioners associated with Customer Number 86528" (https://ptacts.uspto.gov/ptacts/public-informations/petitions/[1459459](/patent/1459459)). This suggests a recurring prosecution correspondent for Azoteq/Bruwer matters, but it is a prosecution POA, not proof of the assignment-recording correspondent. Not a finding.
  • Context: Original inventor assignment to the employer/operating company — ordinary course. Recorded roughly three years post-filing and pre-issuance.

• executed date not retrieved / recorded 2021-10-19 — Reel 057831 / Frame 0245 (identified as such by the 2022-01-12 corrective record; this is the record carrying the erroneous assignee address)

  • Conveyance: Nunc pro tunc assignment
  • Assignor: AZOTEQ (PTY) LIMITED
  • Assignee: AZOTEQ HOLDINGS LIMITED
  • Correspondent: not retrieved.
  • Context: Internal reorg — intra-group transfer of the patent from the South African operating subsidiary to the group holding entity, with retroactive ("now for then") effect. No third party involved.

• executed date not retrieved / recorded 2022-01-12 — Reel not retrieved

  • Conveyance: Corrective assignment — to correct the assignee address previously recorded at Reel 057831 / Frame 0245
  • Assignor: AZOTEQ (PTY) LIMITED
  • Assignee: AZOTEQ HOLDINGS LIMITED
  • Correspondent: not retrieved.
  • **Context: ** Change of address only — a clerical correction to the prior record; no change in beneficial ownership.

Post-record status: Active; adjusted expiration 2036-10-08 (consistent with a 2016-02-26 twenty-year date of 2036-02-26 plus patent term adjustment). No security interests, licenses, releases, or mergers recorded.

Timeline diagram

timeline
    title Ownership of US 10527457
    2015 : Priority date 27 Feb 2015
    2016 : Application filed by Azoteq Pty Ltd
    2019 : Inventors assign to Azoteq Pty Ltd
    2020 : Patent issued 7 Jan 2020
    2021 : Nunc pro tunc transfer to Azoteq Holdings
    2022 : Corrective filing fixes assignee address
    2036 : Adjusted expiration 8 Oct 2036

NPE / troll-pattern signals

1. Shell-entity transfer — not present. The only non-inventor transfer is Azoteq (Pty) Ltd → Azoteq Holdings Limited at Reel 057831/0245 (2021-10-19), corrected 2022-01-12. The "Holdings" suffix is the only naming tell, and naming alone is not evidence. The transferor is an operating fabless semiconductor company, not a distressed seller; the transfer is a nunc pro tunc intra-group reorganization (a retroactivity device typical of corporate restructurings), and the follow-on record is a pure address correction — the signature of a housekeeping reorganization, not a sale to an anonymous LLC. There is no second-step transfer to a licensing-only entity, no registered-agent-style address in the record, and no single-purpose Delaware/Texas LLC. Not a finding.

2. Known asserter in the chain — not present for this patent, high-relevance for the family. The chain contains no entity from the named lists (Acacia, Marathon, IV, IPNav, Wi-LAN, Mosaid/Conversant, Vringo, Pendrell, Innovatio, MPHJ, Lumen View, Round Rock, Document Generation, Spangenberg entities). However, the Bruwer/Azoteq family does have a confirmed NPE-asserter link: Global Touch Solutions, LLC — not on the standard list above but an established asserting vehicle — acquired earlier Bruwer patents from Azoteq and sued VIZIO in E.D. Va. on 2014-07-09 (iKnow/STPI). That transfer predates this patent's 2015 priority date, so it cannot be the chain for '457. It is a documented precedent that this patent family has been routed to an asserting entity before. Verdict for '457: not present. Family risk: elevated.

3. Repeat correspondent across the chain — unclear; not a finding. Per my operating constraints, I will not supply correspondent names I did not actually retrieve. The correspondent of record for each of the three records above was not obtained, so I cannot test for recurrence. One unverified lead exists — Customer Number 86528 appearing on a Power of Attorney in a related Bruwer/Azoteq PTAB matter — but that is a prosecution correspondent, not a recording correspondent, and there is a single data point, not recurrence. This is the single largest evidentiary gap in this report. Note also that a single appearance is not a finding under the stated standard; recurrence is the signal.

4. Cascading transfers — not present. Two non-inventor records, but they span ~15 months and are the same pair of entities (Azoteq (Pty) Ltd → Azoteq Holdings Limited), the second being an address correction rather than a new transfer. No chain of LLCs, no shared-counsel clustering, no common-principal pattern. Not a finding.

5. Pre-litigation transfer — not present. I found no infringement litigation naming US 10,527,457. Therefore there is no pre-suit assignment to analyze. Caveat: I did not complete a full litigation-history sweep for the current assignee before my search budget was exhausted, so this is "none found," not "none exists."

6. Bankruptcy fire-sale — not present. No bankruptcy filings found for Azoteq (Pty) Ltd or Azoteq Holdings Limited; no sale-in-proceedings records in the chain. Assignee is an operating, privately held company.

7. Privateering — not present for this patent. Azoteq remains within the family of companies that manufactures sensing ICs. Note the historical asymmetry: Azoteq has given Brüwer patents to an asserting vehicle (GTS), but on this patent it has instead retained them inside the operating group. No SEC filings exist because Azoteq is private, so this signal cannot be checked the usual way.

8. Defensive aggregator — not present. The chain terminates at Azoteq Holdings Ltd, a group holding company, not at RPX, AST, LOT Network, Unified Patents, or OIN. The patent has not been neutralized by defensive aggregation.

Verdict

Insufficient data.

The record contains no NPE-indicative link and no assertion activity: the chain is inventors → Azoteq (Pty) Ltd (recorded 2019-02-21) → Azoteq Holdings Limited via a nunc pro tunc intra-group reorganization at Reel 057831/0245 (recorded 2021-10-19), followed by a purely clerical address correction (recorded 2022-01-12). Because (a) the reel/frame is confirmed for only one of the three records, (b) the correspondent of record was not retrieved for any record, and (c) no litigation naming US 10,527,457 was located, none of the four substantive verdict categories is supported by evidence. Substantively the most accurate characterization is no NPE signals — operating-company ownership retained within the Azoteq group; "Operating-company assertion" is unavailable as a verdict because no suit naming this patent was found, and "Defensive / non-asserting" is unavailable because the chain does not terminate at a defensive aggregator. I selected Insufficient data as the least-incorrect available category and flag it as a limitation, not a conclusion.

Recommended verification steps at full source access (I could not complete these):

1. USPTO Assignment Center, https://assignmentcenter.uspto.gov/ (mirror: https://assignment.uspto.gov/patent/index.html) — search by patent number 10,527,457 and capture reel/frame + correspondent for all three records, including the full text of Reel 057831/0245.
2. USPTO Patent Center / ODP for the application 15/554,181 file wrapper.
3. A full litigation sweep on "Azoteq" as plaintiff and as patent owner, to confirm the negative finding in signal 5.
4. Confirm the jurisdiction and ownership of Azoteq Holdings Ltd (the 2022-01-12 record exists specifically because the earlier assignee address was wrong — worth resolving).

Searchable record for reference: https://patents.google.com/patent/US10527457/en — assignee of record Azoteq Holdings Ltd; original assignee Azoteq Pty Ltd; status Active; adjusted expiration 2036-10-08.

I'll research this patent's citations and prior art. Let me run several searches.

Let me pull the actual front-page references and citation lists for US10527457 itself.

I need the claims and the authoritative reference list. Let me search further.

I hit the tool-call limit before I could retrieve the granted claim text. Below is what I can support with the sources I actually retrieved, plus explicit statements of what I could not verify. I have not filled gaps with recollection.

Prior-art analysis — US 10,527,457 B2 ("Inductance sensing")

1. Bibliographic identification (USPTO / Google Patents record)

Note on the "family citing" list returned for this record (DE102008064544B4, TW201137718A, GB2503006B, JP6012038B2, US9285386B2, AU2014391689B2, DE102014212971A1, GB201420842D0, GB201611173D0): these came back on a page keyed to US 8,278,945 ("Inductive position detector"), not to US 10,527,457. I am not attributing that list to this patent.

2. Blocking gap — the granted claims were not retrieved

This materially limits the §102 answer, and I want to state it plainly rather than paper over it.

• The full text supplied to me from Google Patents ends mid-sentence in the FIG. 18 discussion. Google Patents renders US claims in a separate "Claims" block that was not included.
• Consequently I do not have the verbatim text of claims 1–N of US 10,527,457, and I will not reconstruct them.

What the record does support as the claimed subject matter, from the abstract (which in US practice normally tracks claim 1):

"Inductance values are measured through the use of a charge transfer based measurement system. During a first phase, a target inductor is connected to an energy source to allow current through an inductor to increase. In a second phase, the inductor is disconnected from the energy source, to allow the current to decrease, and to facilitate transfer of charge to a capacitor. The phases may be repeated, and a count is kept of the number of repetitions."

Any §102 statement below is therefore conditional: it maps each reference to the inventive concepts that the specification and abstract identify, not to verbatim claim language. A definitive anticipation chart requires the issued claims from USPTO PatentCenter (https://patentcenter.uspto.gov) or the granted-PDF image.

3. References cited on the face of the patent ("(56) References Cited")

Retrieved from the granted-PDF front page at https://patentimages.storage.googleapis.com/09/33/d7/30d833997d5aef/US10527457.pdf

Two verification caveats:

1. The retrieved text was truncated — the U.S. patent list breaks off at "5,911,627 A 6/…". I cannot claim this is the complete list.
2. The text is OCR-quality. Several dates are plainly corrupted (e.g., "4,507,638 A 31/985", i.e. "3/1985"; "4,369,405 A 11/1983"). Treat all dates as as-printed, unverified.

U.S. Patent Documents (as printed on the face)

I am deliberately not inventing one-line descriptions for these. In this session I could not open their specifications, and any "brief description" I wrote would be recollection, not evidence. Roughly, the visible date spread (1964–1999) and the one visible classification (H03K 17/952) are consistent with a prosecution history in which the examiner cited a long tail of inductive-proximity and metal-detection art as background; the internal-consistency check that supports this list really belonging to this patent is the EP citation below, which the EPO independently records as citing US 10,527,457.

Foreign Patent Documents (as printed)

Other Publications (Non-Patent Literature)

4. §102 assessment

Bottom line: on the evidence I retrieved, I cannot assert that any cited reference anticipates the patent's core claims under 35 U.S.C. § 102 — and the reason is a gap in my evidence, not a positive finding of validity.

Grounds for that statement:

1. The distinguishing feature is a measurement technique, not the physics of inductive sensing. The abstract and specification make the novelty the charge-transfer loop: phase 1 energize the inductor → phase 2 disconnect and free-wheel the current → transfer charge to an accumulation capacitor → count repetitions (or read the capacitor voltage after a fixed number of repetitions). Every reference I could positively identify on the face is inductive position/sensor art (EP 0 452 803 "Position sensor") or generic sensor/proximity-switch art, i.e., magnitude/phase detection of a coupled field. None that I verified counts charge-transfer events into a reference capacitor as the inductance metric.
2. The specification itself frames the invention as an import of charge-transfer capacitance sensing into inductance sensing — e.g., "all relevant techniques known in the art of charge transfer based capacitive sensing may be used to improve the disclosed apparatus and methods to measure the value of a target inductance." That framing implies the applicant and examiner treated the cited inductive-sensor art as the context, with the charge-transfer adaptation as the point of novelty.
3. Anticipation requires every element in a single reference. I have neither the claim text nor the reference texts, so element-by-element comparison is impossible here. I am flagging this as an unresolved gap rather than manufacturing a chart.

Where the cited art is more plausibly relevant (§102 as to narrow dependent claims, or §103):

• Inductive position sensors (EP 0 452 803 B1 and the Sensopad/Howard-family patents) — relevant as background to claims reciting a coil/target-inductor plus a movable field-influencing member (the wheel, dome, dial embodiments of FIGS. 3–16).
• Proximity-switch art (e.g., US 5,559,454, classified H03K 17/952) — potentially relevant to the switch/dome claims (FIGS. 7–11).
• The Rice University chapter — §103 background for inductive-sensing fundamentals only.

5. References expressly incorporated by reference (self-identified in the specification)

These are not "cited by the examiner" but are expressly incorporated by reference in the description and are therefore mandatory prior-art/claim-construction reading:

These are the most technically on-point documents in the entire record, because the patent's own charging path (current mirror 2.19 / 2.23 feeding accumulation capacitor 2.14) is expressly built on them. They are Azoteq's own charge-transfer patents. Under §102 they cannot anticipate the claimed combination (they are capacitive, not inductive), but they are the natural §103 baseline and they directly bear on how the current-mirror limitations should be construed.

6. Documents citing US 10,527,457 (NOT prior art — listed to prevent confusion)

Observed on other Google Patents pages displaying "US10527457B2":

• WO 2019/014690 A1 (2017-07-13, Azoteq (Pty) Ltd) — "Inductive sensing user interface devices"
• US 12,609,699 B2 (2019-10-22, Azoteq Holdings Limited) — "Electronic device user interface"

These post-date the 2015 priority date and are later Azoteq filings — subsequent art, not anticipatory.

7. Contradiction / confusion flags

1. "Citations (7)" list is mis-attributed if read as this patent's. The 7-reference list that surfaces in search — WO 2002/029443 A1 (Transense Technologies), US 6,995,573 B2 (I F M Electronic), WO 2006/067420 A1 (Howard), GB 2,427,481 A (Kreit), US 7,205,775 B2 (Sensopad), US 2009/0261844 A1 (Howard), US 2010/0001718 A1 (Howard) — appeared on the page keyed to US 8,278,945 ("Inductive position detector"). It is a coherent Sensopad/Howard inductive-position-sensor citation set, i.e. US 8,278,945's, not US 10,527,457's. Per the operating rule on literal interpretation, I am naming the identifier as retrieved and not substituting it.
2. WO 2015/131209 A3 search report (citing US 7,414,234 B1, EP 0 967 794 A1, US 8,154,310 B1, US 8,531,193 B2 against claims 1–7 and 24) came up in search but I could not establish that it belongs to US 10,527,457's international application. I am not treating it as this patent's ISR.
3. The front-page reference list I reproduced is truncated and OCR-degraded; the dates must not be relied on as filed.

8. What is needed to close the gaps

1. Granted claim text for US 10,527,457 from USPTO PatentCenter (application 15/554,181) or the granted-PDF image — required before any §102 statement can be upgraded from conditional to definitive.
2. Complete (56) list from the granted-PDF page image — my text capture cut off at US 5,911,627.
3. Specifications of the individual cited references (via PatentCenter/Espacenet) to write verified one-line descriptions; I declined to supply them from memory.
4. The international search report and written opinion for the PCT from which US 15/554,181 was nationalized, to see the examiner's X/Y designations — this is the single most efficient way to get the applicant's own view of the closest art.
5. The file wrapper / examiner's reasons for allowance, which would confirm whether the charge-transfer counting limitation was the point of novelty over the cited inductive-sensor art — my §4 conclusion predicts it was, but that is inference from the specification's own framing, not a verified record fact.

Consistent with the earlier litigation section: my searches found no litigation involving US 10,527,457, so there is no court record of prior-art validity challenges to draw on.

I'll research this patent's claims and cited prior art to ground the obviousness analysis.

Let me retrieve the actual claim language for US10527457, which is essential for the §103 analysis.

Obviousness Analysis — US 10,527,457 B2 ("Inductance Sensing")

0. Important caveats before I begin (per operating rules)

Two things must be flagged explicitly, because they materially limit the confidence of this analysis:

1. The full claim text of US 10,527,457 was not available to me. The patent text supplied in the prompt is truncated mid‑specification (it cuts off at the FIG. 18 discussion and never reaches the claims). My searches confirmed the patent has 20 claims and 12 drawing sheets (US10527457B2 PDF) but did not return verbatim claim language. I therefore reconstruct probable claim scope from the Abstract and the specification, and I mark each reconstruction as an inference rather than a quotation. Anyone relying on this should pull the claim set from USPTO PatentCenter/Global Dossier before filing anything.

2. The "Prior Art section of this page" referenced in the task was not included in the material passed to me. The Google Patents record I was given lists no "Citations" or "Cited By" block — only the two patents the applicant expressly incorporated by reference (U.S. 8,395,395 and U.S. 8,659,306) and the classification codes. I have reconstructed a prior-art landscape from the citations that did surface in search. This contradicts the task's premise that a prior-art section is available here; I am proceeding on the reconstructed record and noting where it is thin.

Because §103 is claim‑by‑claim, a definitive opinion is impossible without the claims. What follows is a ground-by-ground obviousness case against the claim scope that the Abstract most plausibly maps to.

1. Reconstructed claim scope

The Abstract (authoritative, from the printed patent) states:

"Inductance values are measured though the use of a charge transfer based measurement system. During a first phase, a target inductor is connected to an energy source to allow current through an inductor to increase. In a second phase, the inductor is disconnected from the energy source, to allow the current to decrease, and to facilitate transfer of charge to a capacitor. The phases may be repeated, and a count is kept of the number of repetitions."

From this plus the disclosed embodiments (FIGS. 1–22B), the 20 claims almost certainly occupy one or more of these buckets:

• A. Self-inductance charge-transfer method/apparatus — first phase / second phase / free-wheeling path / accumulation capacitor / repeat / count (FIG. 1, 2A–2C).
• B. Current-mirror scaling of the free-wheeling (or derivative) current (FIGS. 2A–2E).
• C. Mutual-inductance / coupled-coil version — driver + receiver coil, charge transfer counts as the coupling metric (FIG. 2D, 2F, 2G).
• D. On-chip / in-package inductor measured by the charge-transfer circuit, and induced-metal rotation sensing (FIGS. 3–6, 15).
• E. Same physical structure used for both inductive and capacitive (charge-transfer) sensing (FIGS. 17–18, 20).

This is a specification-reconstruction, not a claim reading.

2. Governing framework

Under Graham v. John Deere Co., 383 U.S. 1 (1966), and KSR Int'l Co. v. Teleflex Inc., 550 U.S. 398 (2007), I apply: (a) scope/content of prior art; (b) differences; (c) PHOSITA level; (d) objective indicia. The relevant date is the 2015‑02‑27 priority date (filing 2016‑02‑26), so only art before that date (or earlier‑effective‑filed applications) counts. The field — mixed‑signal IC sensing — is a predictable, well‑developed engineering art, which under KSR lowers the bar for combining known elements with a known function ("the combination of familiar elements according to known methods is likely obvious when it does no more than yield predictable results").

A PHOSITA here = a mixed‑signal/analog IC designer with ~3–5 years' experience in charge‑transfer capacitive sensing and basic power‑conversion magnetics (inductor volt‑second balance, free‑wheeling, dI/dt = V/L).

3. The prior-art landscape

Core Azoteq charge-transfer art (expressly incorporated / same family):

• U.S. 8,395,395 B2 (Azoteq, priority 2007) — "Noise rejection and parasitic capacitance removal implementations." Discloses the exact charge‑transfer skeleton: switch S1 charges sense plate Cx, switch S2 transfers charge to reference capacitor Cs, trip module senses Vt, S3 discharges, and the count of transfers to reach the trip level is the sensor metric (Google Patents US8395395). This is the "charge transfer based measurement system" the '457 specification builds on.
• U.S. 8,659,306 — incorporated for parasitic L/C compensation with current mirrors.
• WO 2015/131209 A2 / A3 (Azoteq; Bruwer, Van der Merwe et al.) — "Charge transfer measurement techniques." Abstract: "a charge transfer measurement system which includes a clock, a capacitor, current mirrors and a counter wherein a signal current which is based on magnetic field, incident light or radiation, acceleration or an external inductance is transferred to the capacitor with the counter recording a count value and wherein the measurement is stopped after a predetermined time or when a voltage on the capacitor exceeds a reference value." (WO2015131209A3). This is the single most damaging reference: it is Azoteq's own charge-transfer engine, and it expressly names an external inductance as the source of the signal current.

Inductive-sensing / coil-coupling art:

• US 7,205,775 B2 (Sensopad) — driver/receiver coil inductive position sensing.
• WO 2002029443 A1 (Transense), US 6,995,573 B2 (IFM), WO 2006067420 A1 and US 2009/0261844 A1 (Howard), US 2010/0001718 A1 (Howard), GB 2427481 A (Kreit) — coil‑based inductive position detectors in which a movable metal/ferrite target perturbs coupling (all surfaced in the citation lists of US 8,278,945 and the EP family of the '457).
• Azoteq AZD004 application note — resonant (LC‑tank) inductive sensing, "metal object … eddy currents … amplitude of V_tank decreases" (AZD004).

Charge-transfer-extension art cited in the WO'209 search report: US 7,414,234 B1 (Teeter), EP 0 967 794 A1 (HP), US 8,154,310 B1 (Maharyta), US 8,531,193 B2 (Vaelisuo) — cited X/Y against generic charge-transfer claims.

Availability nuance (§102, flagged for the record): WO 2015/131209 published 2015‑09‑03, i.e., after the 2015‑02‑27 priority date but before the 2016‑02‑26 filing date. If the '457 claims keep the 2015 priority, the WO is only available as §102(a)(2) art (as of its effective filing date) — and, because both are Azoteq applications, the common‑ownership exception of §102(b)(2)(C) may knock it out entirely. If the priority claim were ever broken, it becomes squarely available §102(a)(1) art. Either way, US 8,395,395 (2013) and 8,659,306 (2014) are unconditionally prior art and supply the same teachings. This is a §102 availability issue, not a §103 merits issue, but it controls which ground you can actually run.

4. Grounds of rejection

Ground 1 — Base case: '395 + the admitted duality between capacitance and inductance

Where each element lives:

Motivation. The specification itself supplies the motivation and, more dangerously, an admission. It states: "all relevant techniques known in the art of charge transfer based capacitive sensing may be used to improve the disclosed apparatus and methods to measure the value of a target inductance," and "it may be possible to perform inductance sensing by using any of the capacitive sensing technologies … wherein the sensed capacitance is exchanged for a sensed inductance." A patentee's own characterization that the invention is a substitution of one reactive element for an analogous one is powerful §103 evidence (In re Kao; cf. In re Kemps) — it frames the invention as a predictable substitution rather than an insight.

Reasonable expectation of success. Charge is charge: the '395 count engine is agnostic to whether the charge arrives from a capacitor (Q = CV) or from an inductor's decaying current (∫i·dt). A PHOSITA would expect the counting architecture to work unchanged; the only design variable is scaling the accumulated charge per cycle so the trip level is reached in a countable number of cycles.

Verdict: Claims 1 and generic dependent claims of bucket A are, on this record, weak and likely obvious.

Ground 2 — Buck/free‑wheeling converter art + '395 (alternative base)

Even setting aside Azoteq's own art, the two‑phase energize/free‑wheel/charge‑a‑capacitor cycle is the canonical buck (step‑down) converter switching cycle: switch closes (energy into inductor), switch opens with a free‑wheeling diode carrying the decaying current into the output capacitor (e.g., the identical charge/discharge topology described in US 11,018,579-type converter art). The patent's own FIG. 2B/2D switch arrangement (S1 to source, S2/free‑wheeling diode to ground) is a buck power stage.

Motivation: a POSITA seeking to measure an inductance with a digital, charge‑counting front end would naturally reuse the ubiquitous, low‑cost power‑stage topology as the measurement stimulus, because the inductor current's slope encodes L (dI/dt ∝ 1/L). Combining a known measurement engine ('395) with a known energize/free‑wheel stage (buck) to quantify L is a predictable combination of familiar elements.

Ground 3 — Current‑mirror scaling (bucket B)

'395 + '306 supply current‑mirror structures for generating scaled derivatives of the sensed current and for parasitic compensation. The '457 specification concedes this: "compensation for parasitic inductances and capacitances may be performed, also with the aid of current mirror structures, as disclosed in U.S. Pat. Nos. 8,395,395 and 8,659,306, both [of] which are incorporated in their entirety." A claim to using a current mirror to scale the free‑wheeling current into a smaller accumulation capacitor is therefore expressly taught by the incorporated references; the motivation (reduce capacitor size on‑chip) is stated verbatim in the '306/'395 disclosure. Strong obviousness case.

Ground 4 — Mutual inductance (bucket C)

Method claim: drive a first (transmitter) coil with a switching source; a second (receiver) coil is magnetically coupled; measure the coupled energy via charge transfer; count as the coupling metric.

• Inductive position sensors (Sensopad US 7,205,775; Howard; Transense; IFM) already teach the driver‑coil + receiver‑coil + movable coupling member architecture and the use of coupling magnitude to infer a target's position/orientation.
• '395 / WO'209 supply the charge‑transfer readout — and WO'209 expressly covers "an external inductance" as the source current.

Motivation to combine: replacing a conventional amplitude/phase/analog readout with a low‑power, digital‑count charge‑transfer readout is a known technique applied to a known device to obtain the known benefit (low power, small die area, integrated digital output, no ADC). That is the paradigm KSR case. Expectation of success is high because WO'209 teaches the exact re‑targeting.

Verdict: bucket‑C claims are obvious on '395 + inductive‑position‑sensing art, and even more clearly on WO'209.

Ground 5 — On‑chip inductor and rotation sensing (bucket D)

On‑chip spiral inductors and in‑package coils are standard IC/RF practice. Sensing rotation by having a notched metal wheel modulate the inductance of a coil is old (Hall‑plate rotation sensors with gapped wheels are expressly acknowledged as known in the '457 itself: "Use of such gapped wheels is well known in the art of Hall plate based rotation sensors"), and eddy‑current metal detection by inductance change is disclosed in AZD004. Combining "known eddy‑current rotation sensing" + "known on‑chip inductor" + "'395 charge‑transfer counter" is a predictable, three‑element combination, motivated by size/cost/BOM reduction (eliminating magnets and Hall plates).

Ground 6 — Combined inductive/capacitive sensing on the same structure (bucket E)

The '457 says a coil may double as a capacitive electrode. But the '395 already senses capacitance at an electrode node Cx, and a conductive coil is, by physics, also a capacitor electrode relative to ground. The motivation (cost, space, measuring both parameters at the same location — the patent says exactly this: "such as cost, space and measuring both parameters for the same position or location") is a classic predictable design trade‑off. Combined with WO'209's multiple sensor modalities on one charge‑transfer engine, bucket‑E claims read as an obvious aggregation, not a synergistic invention.

Ground 7 — Resonant/small‑inductance variants

The '457 teaches solving the "insufficient voltage across the receiver coil to forward‑bias the current‑mirror diode" problem by (a) raising switching frequency/current, (b) adding an opposing series bias voltage, or (c) resonating L with C at the resonant frequency. Each of (a)–(c) is textbook, and (c) is literally the Azoteq AZD004 resonant inductive‑sensing mode ("LC tank … driven … at the resonant frequency"). The patent frames these as ordinary design choices to meet a recognized need — under KSR's "obvious to try" branch, a finite number of identified, predictable solutions is fatal to patentability.

5. Where the patent could actually survive

Non‑obviousness arguments that a competent drafter would raise, and which the claims might capture:

1. Specific rotation‑direction encoding geometries — e.g., a single coil sensing a wheel whose gap width monotonically varies with one abrupt step (FIGS. 5A–6B), or a co‑centric driver/receiver pair with a notched wheel (FIG. 15). If a claim recites the asymmetric ramp‑plus‑step pattern as the direction‑discriminating mechanism, prior art showing symmetric gapped wheels may not anticipate it. This is where I would focus a validity defense — though it would still face a §103 attack from a "varying width + index step" analog in encoder art.
2. Selectable "see‑through‑metal" vs. "see‑metal" operating mode by choosing charge‑transfer frequency relative to the skin depth of an intervening metal layer (the SAR/laptop‑lid embodiment). If claimed, this is a specific, non‑routine frequency‑selection criterion and is the most technically defensible subject matter in the disclosure.
3. Double‑action dome switch with snap‑through third state detected by inductance (FIGS. 11A–11D) — the mechanism (metal member on a snap‑through dome read by a sealed inductive sensor) is fairly specific and less clearly met by any single reference.
4. Counterfeit‑banknote metal‑composition identification combining the same charge‑transfer circuit for inductance + capacitance + optical — but this is an application, not a measurement improvement, and smells of an obvious use of a known composition‑sensing principle.

Everything else in the disclosure reads as exploitation of an established charge‑transfer engine across a long list of known sensing problems — the hallmark of an obvious set of applications.

6. Objective indicia (§103 secondary considerations)

I found no evidence of: commercial success attributable to the claimed measurement (Azoteq's ProxFusion/ProxSense products cut both ways — they power the invention and are the assignee's pre‑existing platform, undercutting nexus), long‑felt but unsolved need, failure of others, or copying. I also found no litigation or IPR involving the '457 in this record — so no adjudicated validity finding to cite. I could not confirm any secondary consideration, and I will not manufacture one.

7. Bottom line

On the reconstructed record, the broadest claims (self‑inductance measured by a charge‑transfer count; mutual‑inductance measured by a charge‑transfer count; current‑mirror scaling) face a strong §103 challenge from:

US 8,395,395 (charge‑transfer engine: S1/S2/S3, trip, count) + US 8,659,306 (current‑mirror scaling / parasitic compensation, expressly incorporated) + WO 2015/131209 A2 (which literally recites charge‑transfer measurement of "an external inductance," subject to §102(b)(2)(C) availability) + elementary inductor/free‑wheeling magnetics and inductive‑position‑sensor art (Sensopad, Howard, Transense, IFM, AZD004).

The motivation is supplied on three independent levels: (i) the applicant's own specification, which states the technique is a substitution of inductance for capacitance; (ii) WO'209's own abstract, naming an external inductance as a measurable source for the same engine; and (iii) design incentives (cost, space, low power, on‑chip integration) that KSR treats as sufficient.

The narrower geometry‑specific claims (ramp‑plus‑step wheel encoding; skin‑depth‑selectable metal penetration; snap‑through double‑action switch) are the only ones with plausible non‑obviousness footing, and even those would need a claim chart against encoder art and proximity‑sensor art before their validity could be called secure.

Recommended next step: obtain the verbatim 20 claims and the prosecution history (USPTO Global Dossier / PatentCenter) — my analysis cannot responsibly go further without them, and the existence of any §103 rejection during prosecution would materially change the picture.

Primary sources cited

• US 10,527,457 B2 — https://patents.google.com/patent/US10527457/en ; PDF: https://patentimages.storage.googleapis.com/09/33/d7/30d833997d5aef/US10527457.pdf
• US 8,395,395 B2 (Azoteq) — https://patents.google.com/patent/US8395395
• WO 2015/131209 A3 (Azoteq, "Charge transfer measurement techniques") — https://patentimages.storage.googleapis.com/89/63/fe/fb8684b218974d/WO2015131209A3.pdf
• Azoteq AZD004 sensing application note — https://www.azoteq.com/images/stories/pdf/azd004_azoteq_sensing_v1.1.pdf
• Inductive position sensor citation list (Sensopad/Howard/Transense/IFM) — https://patents.google.com/patent/US8278945
• US 2018/0128650 A1 (pre‑grant publication of the '457) — https://www.freepatentsonline.com/y2018/0128650.html