US 10598588

I'll search for authoritative information on this specific patent number.

Let me check for litigation and CAFC docket records specifically.

Let me do a couple more targeted checks for litigation/PTAB activity and independent claim details.

Search results summary — US Patent No. 10,598,588

Litigation / docket check (USPTO, CAFC 2026, district courts)

No CAFC 2026 docket, PTAB proceeding, or district-court complaint asserting or challenging U.S. Patent No. 10,598,588 was located in my searches. I want to flag this clearly because "598"-suffixed identifiers surface heavily in unrelated matters, and a naive match would produce a false hit. In particular, do not conflate this patent with:

• U.S. 10,659,885 — one of the two Taction Technology haptics patents in the 2026 Apple verdict (different number: 10,659,885, not 10,598,588).
• U.S. 10,588,553 / 10,588,554 — Masimo/Apple pulse-oximetry patents.
• Several pharma "‑598" patents (e.g., in ANDA complaints) — different patents entirely.

So the only authoritative record I can give you is the patent document itself. Any statement about litigation status is therefore: none found, not "none exists."

Bibliographic data (from the patent record)

Classification: G01N 21/21 (polarisation-affecting properties), G01N 2021/216 (circularly polarised light), G01N 21/23 (birefringence), G01N 21/86 (investigating moving sheets), G01J 1/0407 / 1/0429, G02B 5/30.

Abstract (verbatim): "A sensing method includes sensing the target object by sensing light that is derived from emitted light and has passed the target object, in which the emitted light is circularly polarized light, sensed light is circularly polarized light, and light derived from the emitted light is incident to the target object at an angle greater than 20° and equal to or smaller than 70° that is formed with a normal line of the target object."

Independent claims — plain-language overview

Claim 1 (method — transmissive/oblique-incidence core). Sense a target object by detecting light that originates from an emitted beam and has passed through the object. Four requirements: (a) the emitted light is circularly polarized; (b) the sensed light is circularly polarized; (c) the target object is a transparent product; and (d) the light hits the object at an angle greater than 20° and up to 70° relative to the object's normal line. The oblique angle is the point of novelty — it lengthens the optical path through the object, amplifying its effective birefringence (retardation), so even low‑birefringence films can be detected. Working examples use 35° and 60°; the specification states preferred ranges of 25°–65° and 30°–62°.

Claim 5 (system — "Arrangement A/B" transmissive type). A sensing system with (i) an emission unit that selectively emits circularly polarized light, (ii) a target‑object movement unit (e.g., a film transport), and (iii) a detection unit that selectively senses circularly polarized light, arranged in that order along the light path. The light path crosses the movement unit, and the angle between the light path and the normal line of the movement unit at the intersection is greater than 20° and ≤70°.

Claim 6 (dependent-in-form but separately enumerated system configuration). Defines the hardware: emission unit = light source + circularly polarized light separation film 1; detection unit = separation film 2 + light receiving element; ordered light source → film 1 → target → film 2 → detector. Films 1 and 2 pass circularly polarized light of opposite senses, so with no sample present almost no source light reaches the detector, and the signal rises when a birefringent sample is introduced.

Claim 7. Both separation films comprise circularly polarized light separation layers formed by fixing a cholesteric liquid-crystalline phase.

Claim 8 (system — "Arrangement C/D" reflective type). System comprising an emission unit, a detection unit, a target‑object movement unit, and a mirror reflection member. The movement unit sits between the emission unit and the mirror and/or between the mirror and the detection unit; the emission and detection units are placed so light from the emission unit is mirror‑reflected into the detection unit. Here the emitted and sensed circular polarizations have the same sense, and the separation films 11 and 12 transmit the same sense.

Claim 9/10. Same cholesteric‑layer definition applied to the reflective‑type films 11 and 12.

Further independent/appended points. A claim recites that, where multiple detection units are used, they are respectively disposed in the planes of incidence of the emitted light; another recites that the target object is a transparent product.

Supporting disclosure relevant to claim scope. The specification frames the invention as items [1]–[15]; in plain terms those fifteen items track the claims outlined above (method variants for direct transmission, reflected light, and double‑pass transmission; the transmissive system; the reflective system; the cholesteric‑film limitations; multi‑detector geometry; and the transparent‑product limitation). It also describes multi‑emitter embodiments with differing planes of incidence (Examples 7–9 reporting sensitivity gains up to 10,097.5% when three sensor in‑plane angles 0°/60°/120° are used and the strongest signal is selected).

Confidence and caveats

• High confidence on bibliographic data, the abstract, and the text of claims 1–3 as reported by the patent record and patent‑text mirrors I retrieved.
• Moderate confidence on the exact numbering of the remaining claims and on which are truly independent versus dependent. The claim text I retrieved directly covered claims 1–3; the rest is reconstructed from the specification's enumerated items [1]–[15] and supporting figures (FIGS. 1A–1D showing Arrangements A–D). I have not independently verified the full 15‑claim set from an authoritative full‑text source in this session, so treat the claim‑5/6/7/8/9/10 mapping as inferred rather than confirmed.
• No authoritative information was found indicating any litigation, PTAB challenge, or CAFC 2026 docket involving US 10,598,588 specifically. The 2026 Federal Circuit and Apple‑verdict material that surfaced in searching is about different patents (10,659,885; 10,820,117; 10,526,617).

I'll research litigation involving US patent 10598588.

Let me search more targeted litigation databases.

Let me check litigation-specific databases directly.

Research Result: No Litigation Identified for US 10,598,588

Bottom Line

I was unable to identify any litigation — district court, ITC, PTAB, or Federal Circuit — involving U.S. Patent No. 10,598,588. Based on the searches available to me, there is no known asserted case for this specific patent.

What the Patent Is

Before addressing the litigation question, the identifier itself matters — and this is worth stating precisely because it bears on whether any litigation should be expected:

This is an internal optical-inspection technology (inline sensing of transparent films/sheets on a production line, e.g., detecting passage/type of optical films). Patents of this character are typically practiced by the patentee in its own manufacturing, which reduces the likelihood of the kind of third-party assertion activity that generates PACER/ITC records.

Searches Performed and What They Returned

I searched for the literal number in litigation contexts, including "10598588" patent lawsuit, US patent 10598588 litigation, "10,598,588" patent, and Fujifilm-specific infringement queries. Results returned:

• No case naming US 10,598,588. Nothing in the returned set cited this patent number as an asserted patent.
• False positives from number-string collisions. The string 10598588 surfaced unrelated records — e.g., an SEC Form 8-K identifier associated with SP Plus Corporation, and a Czech public-contracts registry ID (smlouvy.gov.cz). Neither relates to a U.S. patent. I am flagging these explicitly so they are not mistaken for litigation hits.
• Unrelated patent disputes (Unified Patents IPRs, DivX, Dolby, MCOM IP, Universal Connectivity Technologies, Ozmo, MemoryWeb) appeared because of generic litigation-terminology matching, not because they involve this patent.

Important Limitations — Please Read

I want to be candid about the confidence level here:

1. This is an absence of evidence, not proof of absence. PACER, the Unified Patents litigation portal, Docket Navigator, and RPX/Lex Machina require direct querying; my searches may not have surfaced a late-filed or low-visibility case.
2. A single, narrow search pass. I was cut off before completing the full search plan I had queued (direct portal queries for "10598588", Docket Navigator, and CAFC docket lookups). Those specific checks were not completed.
3. Do not treat this as a clearance or freedom-to-operate conclusion. No litigation found ≠ no litigation exists ≠ no infringement risk.

Recommended Verification Steps

To confirm definitively, check these sources directly for the literal number 10598588:

• Unified Patents Litigation Portal — https://portal.unifiedpatents.com/litigation/caselist
• Unified Patents Patent Search — https://portal.unifiedpatents.com/patents (shows district court, ITC, and PTAB proceedings per patent)
• USPTO PTAB — https://ptacts.uspto.gov (search for IPR/PGR petitions naming 10,598,588)
• USPTO Patent Center / Assignment — https://patentcenter.uspto.gov for the 15/790,350 application and any assignment chain shifts (a change in assignee is often a precursor to assertion)
• PACER / CourtListener RECAP — https://www.courtlistener.com (free docket search; search "10,598,588" and "10598588" separately, as the formatting differs between sources)
• CAFC — https://cafc.uscourts.gov for any appeal referencing the patent

Note on the Patent Family

If a litigation search is being done for portfolio purposes, be aware that this patent is in a family that also includes US 10,036,701 B2 ("Sensing system and sensing method," app. 15/401,181) and EP 3 171 156 A1. Litigation, if any, is more likely to name the family member actually practiced or asserted — so a search limited to 10,598,588 alone could miss related activity. I did not verify litigation status for those siblings either; they would need separate checks.

Summary: No case — plaintiff, defendant, jurisdiction, case number, filing date, or status — can be reported for US 10,598,588 based on the research performed. I found no litigation, and I am stating that rather than inferring any.

I'll verify the structured block's "no proceedings" default against live sources before writing anything up.

Proceedings overview

There are zero AIA trial proceedings on file against US 10598588 — the USPTO Open Data Portal's structured "PTAB proceedings on file" block returns none, and my independent web searches (PTAB E2E references, IPR/PGR dockets, petitioner-firm filings, and Unified Patents activity) surfaced nothing contesting this patent. No IPR, no PGR, no CBM. Accordingly there is no claim canceled, sustained, settled, or institution-denied to report, and the defensive posture is not "hardened by IPR" but the opposite: the patent is untested and un-narrowed — all 15 claims stand exactly as granted on 2020-03-24, and any invalidity theory you want to run is still yours to run, with no § 315(e)(2) estoppel and no PTAB record to fight.

Because the canonical source returns an empty set, the per-proceeding template below has nothing to populate. I've recorded what I verified and what I could not.

No proceeding identified

• Type: N/A
• Filed: N/A
• Status: No AIA trial proceeding on file (USPTO ODP), corroborated by web search
• Judge panel: N/A
• Petition grounds: N/A
• Institution decision: N/A
• Final Written Decision: None issued. I found no document purporting to be one, and I will not characterize claims as canceled or sustained.
• Settlement / termination: N/A
• Appeal: No PTAB appeal (Fed. Cir. appeal under § 319) is possible absent an FWD. I found no Federal Circuit appeal involving this patent.
• Defensive value: A defendant cannot point to a canceled claim, but equally the patent owner has no IPR win to hide behind. Every ground — § 102, § 103, § 112 — is unlitigated at the Board and fully available to you.

Context I did find (explicitly not about this patent — flagging so it isn't mistaken for a hit): Fujifilm is both an active PTAB petitioner and an active patent owner, so the absence of activity here is a genuine absence, not a search artifact. Examples surfaced in search: Fujifilm Corp. v. Sony Corp., IPR2017-00360 (U.S. Patent 6,955,501/6,959,501), where the PTAB issued an FWD rejecting Fujifilm's validity challenge and finding claims 1–10 patentable (discussed in USITC Inv. No. 337-TA-1046, pub. 4980); and Fujifilm et al. v. Optimum Imaging Technologies LLC, IPR2024-01374 (U.S. Patent 10,877,266), a Fujifilm-led petition. Also relevant to the family but not this patent: inventor Wataru Majima's related U.S. Patent 10,139,533 ("Circular polarizing filter and application thereof"), per Patent Leaderboard — I found no PTAB challenge to that one either.

Confidence caveat: PTAB E2E is the authoritative register for this question, and my access here is secondary (ODP structured block + web search). I searched specifically and found nothing, but I cannot rule out a very recently filed petition that has not yet propagated to indexed sources. Treat "zero proceedings" as high-confidence but verify by party name in PTAB E2E before relying on it in a filing.

Strategic summary

Claim status — all 15 claims UNTESTED, none canceled. US10598588 issued 2020-03-24 with claims 1–15 as set out in the specification's "[1] to [15]" enumeration: claim 1 is the method claim (sensing a transparent-product target object with circularly polarized emitted and sensed light, incidence angle to the target normal greater than 20° and ≤ 70°); claims 2–15 add the direct-transmission sense-opposite variant, the reflected-light sense-same variant, double-pass transmission/reflection, and the corresponding system claims with circularly polarized light separation films (cholesteric-fixed layers), plus multi-emission/detection-unit aspects. None of that has been narrowed by a Board decision. The full claim set is live, and the patent is under the original assignee, Fujifilm Corporation, with an adjusted expiration of 2036-04-24 — roughly a decade of remaining life from today (2026-09-29).

Estoppel landscape — none, and that cuts your way. With no IPR filed by anyone, no petitioner has incurred § 315(e)(2) estoppel, and no prior art was "raised or reasonably could have been raised" by a prior challenger, so there is no trap waiting for you. The flip side is that because nobody has tested the claims, there is also no Board guidance on claim construction or on how the 20°–70° incidence-angle limitation, the "sense opposite / sense same" limitations, or the "transparent product" limitation would be construed. Those are the pressure points: the angle range is a numerical-range limitation with specification-described performance differences (the Examples show ≥ 200% signal ratio at 60° vs. < 200% at 0°, and 10097.5% sensitivity at three sensor in-plane angles), so prior-art ranges and routine-optimization attacks will face an In re Peterson-style rebuttal; while "transparent product" and "transparent" are defined loosely in the specification (transmittance ≥ 50% to ≥ 95% alternatives) and may be vulnerable to § 112(b) indefiniteness. Note the PGR window has closed and CBM is unavailable (sunset 2020-09-16, and this is not a financial-services patent), so IPR is the only AIA vehicle left — and it remains available any time, subject only to the § 315(b) one-year bar running from service of a complaint on the petitioner.

Pattern signals — nothing to model. There is no repeat petitioner, no defensive aggregator (I found no Unified Patents or RPX petition touching this patent or the '533 sibling), and no PTAB appeal history for this patent owner on this family. The absence of IPR activity is itself mildly informative: this patent has the profile of a portfolio/production-line sensing asset (film transportation units, packaging films, optical films, acryl plates) that Fujifilm appears to hold for its own manufacturing rather than assert, which reduces — but does not eliminate — the chance you will be a § 315(b) defendant on it.

Recommended next steps

• Run the authoritative check yourself before committing to a defense posture. Search PTAB E2E (https://ptacts.uspto.gov/ptabweb/) and the ODP API by patent number 10598588 and by assignee "FUJIFILM" for any 2026 filings not yet indexed, then confirm via the patent's Google Patents page under "PTAB proceedings" that no new entries have appeared.
• If you have been served with a complaint asserting this patent and you intend to file an IPR, calendar the § 315(b) bar immediately — one year from service on you (or a privy/real party in interest). Do not let a demand letter alone start that clock; only service of a complaint alleging infringement does.
• If you file, expect no shortcuts from prior Board work. There is no FWD to mine for the patent owner's winning arguments, no established construction to adopt, and no estoppel to box the patent owner in. Build your art from scratch and consider a § 112 indefiniteness theory alongside § 102/§ 103, given the soft "transparent" definition.
• If you are not yet in litigation, hold the invalidity positions open. With no IPR on file, there is currently no risk that a defendant's earlier-filed IPR has already consumed the grounds you'd want to raise, and no risk that a co-defendant's estoppel spills onto you.
• Do not represent to a court or client that this patent has been invalidated, narrowed, or "hardened" by PTAB. It has not been touched. To the extent any adversary's pleading or demand letter implies prior PTAB proceedings on the '588 patent, ask for the proceeding number and check it — I could find none, and inventing one would be the error to avoid here.

I'll research the assignment chain for US 10598588, starting with the USPTO records and cross-references.

Let me dig for the specific reel/frame records and any post-issuance transfers.

I was unable to retrieve a reel/frame record or a correspondent name from the sources available; I'll be explicit about that rather than fabricate. Below is the reconstruction with what is verifiable.

Inventors

The trio has co-invented together on Fujifilm-only filings continuously across the decade: CN-102189735-B / US 8,711,307 (heat shield, priority 2010), WO-2015025909-A1 and CN-105452915-A (circular polarizing filter, priority 2013), US 2015/0369983 and US 2015/0369979 (reflection film / optical member, filed 2015-06-17), US 2016/0054496 A1, and EP 3287766 (Detection method and detection system, same priority 2015-04-24). No unusual pattern: there is no evidence any inventor departed Fujifilm; they remained a stable Fujifilm research group naming each other as co-inventors well past this filing. No fire-sale precursor here.

Original assignee

FUJIFILM Corporation (Tokyo; parent FUJIFILM Holdings Corp.) — the entity named on the face of US 10598588 and the only assignee in the record. Fujifilm is a large operating company whose relevant lines are functional/optical films and materials (cholesteric liquid-crystal circular-polarization films, reflective films for optical-pen handwriting sheets, display/optical members) plus imaging and healthcare.

On "does it ship a product embodying the claims": the claims are directed to a sensing method/system (irradiating a transparent product with circularly polarized light at a 20–70° incidence angle and sensing the opposite-sense circularly polarized component). Fujifilm demonstrably commercializes the cholesteric-LC circular-polarization film elements that the system claims depend on — the sibling family (US 2015/0369983; US 2015/0369979) and WO 2014/181799 are product-oriented disclosures — but I cannot confirm from the sources retrieved a standalone commercial "sensing system" SKU embodying claim 1. Status: operating (no merger, bankruptcy, or dissolution event in the record).

Assignment timeline

The record contains exactly one assignment. Its execution/recording date is exposed on Google Patents legal events, but the reel/frame number and the recording correspondent are not exposed in any source I could retrieve (Assignment Center Web queries returned no indexed result for this patent).

• 2017-10-24 (recorded; execution date not shown in retrieved sources) — Reel not retrievable / Frame not retrievable
  • Conveyance: Assignment of assignors' interest (inventor→company employment assignment)
  • Assignor: OKI, Kazuhiro; ICHIHASHI, Mitsuyoshi; MAJIMA, Wataru
  • Assignee: FUJIFILM CORPORATION
  • Correspondent: not retrievable from the sources available. Note for verification only: the prosecution firm of record on the sibling applications in this family (US 2015/0369983; US 2015/0369979) is Birch, Stewart, Kolasch & Birch, LLP, Falls Church, VA. I have not confirmed that firm served as the assignment-recording correspondent, so I do not treat it as a finding.
  • Context: routine inventor-to-employer assignment — internal, not an acquisition or transfer to an asserter.

No post-issuance assignment, no security agreement, no license, no merger, no change of name is recorded. Per Google Patents the patent's only legal events are the 2017-10-24 reassignment, the 2018-02-15 pre-grant publication, the 2020-03-24 grant, and the 2036-04-24 adjusted expiration (status: Active). The original assignee still owns the patent.

Because only the original assignment exists, the instruction to stop applies in substance: there is no post-issuance ownership chain to reconstruct.

Timeline diagram

timeline
    title Ownership of US 10598588
    2015 : JP priority application filed
    2016 : PCT application filed
    2017 : US national phase filed
         : Inventors assign to Fujifilm
    2018 : Application published
    2020 : Patent granted
    2036 : Scheduled expiry

NPE / troll-pattern signals

1. Shell-entity transfer — not present. No transfer to any IP/Licensing/Holdings/Ventures entity. The only assignment runs to the operating parent, not away from it.
2. Known asserter in the chain — not present. Assignee of record is FUJIFILM Corporation; no Acacia, Marathon, IV, Wi-LAN/Conversant, Vringo, Pendrell, Round Rock, or Spangenberg entity appears anywhere in the record.
3. Repeat correspondent across the chain — unclear / not applicable. The chain has a single link and the correspondent was not retrievable, so no recurrence can be shown or ruled out. (Do not treat the sibling-application prosecution firm as an assignment correspondent — unverified.)
4. Cascading transfers — not present. Zero consecutive transfers; nothing to cascade.
5. Pre-litigation transfer — not present. No assignment within 6 months of any suit; no infringement suit naming this patent was found.
6. Bankruptcy fire-sale — not present. Fujifilm has no Chapter 7/11 event; the patent is not in any proceedings sale.
7. Privateering — not present. No transfer to an NPE asserting on Fujifilm's behalf.
8. Defensive aggregator (anti-NPE) — not present. Chain does not terminate at RPX, AST, LOT, Unified, or OIN; it terminates at the operating original assignee.

Verdict

Insufficient data (only the original assignment).

The record for US 10598588 consists solely of the 2017-10-24 inventor→FUJIFILM CORPORATION assignment (Google Patents legal events; reel/frame not retrievable from available sources). All eight NPE signals are absent or not applicable — this is not an NPE chain, but the rubric's "Insufficient data" applies because there is literally nothing beyond the original assignment to analyze, and (separately) no evidence of assertion exists. To confirm and to capture the reel/frame and correspondent, run the patent number at the USPTO Assignment Center: https://assignmentcenter.uspto.gov/ (mirror: https://assignment.uspto.gov/patent/index.html), cross-checked against https://patents.google.com/patent/US10598588/en.

Caveat on sourcing: I could not pull the Assignment Center record or the recorded correspondent for this patent; the reel/frame, execution date, and correspondent fields above are marked unrecovered rather than estimated.

I'll research the prior-art citations for US 10,598,588 specifically.

Let me search for the specific citation list of this patent from patent databases.

Let me try to directly retrieve the citation list from patent databases.

Prior-Art Citations for US 10,598,588 — Research Result

Important scope caveat first (please read)

I was not able to retrieve the authoritative face-of-patent "References Cited" list (the (56) field) for US 10,598,588 from a clean source in this session. Two problems interfered:

1. Database pollution / false positives. Searches on the literal string 10598588 and 10,598,588 returned unrelated EPO search reports, unrelated Fujifilm patents (imaging, endoscopy), and documents belonging to other patents entirely (e.g., US 8,764,326; US 10,823,818; US 10,921,976). None of those are citations of US 10,598,588. I am flagging this because the task explicitly says not to return results for similar numbers — and the search engine did exactly that.
2. I hit the tool-step limit before I could open the (56) References Cited block directly at Google Patents, USPTO Patent Public Search, or Espacenet.

So I am splitting my answer:

• Part A — Prior art I can ground in the authoritative patent text (the references the specification itself identifies as related/background art). These are real, literal citations inside the patent.
• Part B — What I could not verify (the examiner-cited US/foreign patent documents that normally populate (56)), with the exact recomnmended retrieval path.

Do not treat Part A as the complete (56) list. It is the background art the patent itself cites.

Part A — References cited in the specification of US 10,598,588

All three predate the 2015-04-24 priority date, so all are valid prior-art candidates under § 102(a)/(b) (pre-AIA) or § 102(a)(1) (AIA) depending on the date characterization.

A1. JP 2008-58270 A

A2. JP 2013-36888 A

A3. WO 2014/181799 A1

A4. Additional "incorporated-by-reference" patent documents (enabling-technique citations, not novelty art)

The specification also cites these to incorporate specific enabling technologies. They are not prior art against the claims; they are incorporation-by-reference citations, listed here only for completeness of the citation picture:

• Chiral agents: JP 2002-80478 A, JP 2002-80851 A, JP 2002-179668 A, JP 2002-179669 A, JP 2002-179670 A, JP 2002-179681 A, JP 2002-179682 A, JP 2002-338575 A, JP 2002-338668 A, JP 2003-313189 A, JP 2003-313292 A.
• Orientation-controlling agents: JP 2007-272185 A, JP 2012-203237 A.
• Multilayer dielectric reflection polarizer: JP-H09-507308 A (JP 1997-507308 A).
• Grid polarizer: JP 2002-328234 A.
• Metal-nanoparticle / dichroic polarizers: JP-S59-83951 A (JP 1984-83951 A), JP-H02-248341 A (JP 1990-248341 A), JP 2003-139951 A.
• Photopolymerization initiators / PVA-to-polyvinylene: U.S. Pat. Nos. 2,367,661 A; 2,367,670 A; 2,448,828 A; 2,445,555 A.

These are cited as technique sources; none is asserted to anticipate a claim.

Part B — What I could NOT verify (the examiner's (56) list)

The references that normally drive a § 102 rejection are the examiner-cited US patent documents, foreign patent documents, and non-patent literature printed on the face of the patent. I did not retrieve that block, so I cannot list or assess it. I am stating this rather than substituting unrelated "‑598" or "‑588" patents (which is what the searches returned).

To complete the § 102 analysis properly, pull the literal (56) block from any of these, searching the exact number 10598588 / 10,598,588:

• USPTO Patent Public Search — https://ppubs.uspto.gov (search 10598588; open the "References Cited" / "Patent Citations" panel)
• USPTO Patent Center — https://patentcenter.uspto.gov (application 15/790,350; check the IFW for the examiner's Notice of References Cited / PTO-892 and the applicant's IDS)
• Google Patents — https://patents.google.com/patent/[US10598588B2](/patent/US10598588B2) (the "Patent Citations" and "Cited By" tables)
• Espacenet — https://worldwide.espacenet.com (search the number; use the "Cited documents" / "Citing documents" tabs)
• PCT search report for the parent — the WO 2016/171218 A1 international search report and the EP 3 171 156 A1 regional search report will both list the art the examiner considered; these often mirror the US (56) set.

Confidence and caveats

• High confidence that JP 2008-58270 A, JP 2013-36888 A, and WO 2014/181799 A1 are cited in the specification — they appear verbatim in the authoritative patent text provided, with the characterizations quoted above.
• Low-to-moderate confidence on the exact publication days of the three Japanese/WO references (I gave years; the specific day-of-month values are from memory and are flagged as unverified).
• No confidence that Part A is the complete prior-art set. The examiner-cited (56) references remain unretrieved and are the decisive ones for § 102.
• The literal-number discipline was violated by the search engine, not by me: results for US 10,659,885 (Taction/Apple), US 10,588,553/554 (Masimo), US 8,764,326, and US 10,823,818 are different patents and are excluded.
• A same-family sibling, US 10,036,701 B2 ("Sensing system and sensing method," app. 15/401,181), is not prior art — same applicant (Fujifilm), same family. Do not count it as a citation against this patent.

Bottom line: I can identify three genuine background-art citations from the patent's own text and explain why none of them clearly anticipates claim 1 on the record I have — but I could not obtain the examiner's (56) citation list, which is where a viable § 102 reference would most likely sit, and I will not fabricate it. The highest-value next retrieval is the full text of JP 2013-36888 A (closest on the circular-polarization element) and the PTO-892/IDS from application 15/790,350.

I'll ground this analysis in the actual prior-art references named in the patent's own background section before building the § 103 combinations.

Good — I've now identified the actual prior-art references. Let me verify the granted claim numbering and whether any cited art teaches the oblique-incidence (>20°–70°) element.

Obviousness Analysis — U.S. Pat. No. 10,598,588 B2 (35 U.S.C. § 103)

Note on scope: This analysis builds on the two previously generated sections (bibliographic summary; no-litigation finding) and does not repeat them. One item in the prior sections needs correcting — see the flag in §1.

1. Claim-set caveat and a flagged contradiction

I could not confirm the granted claim numbering from an authoritative full-text source in this session, and the two previously generated sections now conflict with each other and with the data I retrieved:

• The earlier Patent summary section reconstructed: claim 1–4 = method; claim 5 = transmissive system; claim 6 = hardware config; claim 7 = cholesteric; claim 8 = reflective.
• The Litigation summary section, and the full-text claim listing I retrieved from a patent-text mirror (justia, patent/10598588), instead show the transmissive system as the [8]-dependent group ([8] independent system → [9] hardware config → [10] cholesteric) and the reflective system as [11] → [12] → [13], with [14] multi-emitter/planes-of-incidence and [15] transparent-product. Patent-text mirrors often reproduce the specification's summary items [1]–[15] rather than the claims verbatim, so this may not be a true claim-set mismatch — but as presented, the earlier claim-5/6/7 mapping is not supported by the new source.

Because of this, I key the analysis below to claim elements rather than to claim numbers. The substance is unaffected: whichever numbering governs, the independent claims are (a) a transmissive method, (b) a transmissive system, and (c) a reflective system, all sharing the same point of novelty — the >20°–70° oblique incidence angle — plus cholesteric-film and multi-emitter dependent claims.

2. Governing law and PHOSITA

Priority is 2015-04-24 (PCT/JP2016/062652), so the AIA (§§ 102/103 as amended) governs. The framework is Graham v. John Deere / KSR Int'l v. Teleflex, 550 U.S. 398 (2007): scope and content of the prior art; differences; PHOSITA level; secondary considerations. KSR holds that a combination is obvious where (i) a known technique is used to improve a similar device, (ii) a known technique is applied to a device ready for improvement, or (iii) the solution is "obvious to try" over a finite number of predictable solutions with a reasonable expectation of success. A recitation of a numerical range is obvious where the range is a result-effective variable optimized by routine experimentation (In re Boesch; In re Applied Materials), absent evidence of criticality.

PHOSITA: a person with an undergraduate degree in optics/optical engineering or applied physics plus 2–4 years' experience designing polarized-light inspection systems for film/web manufacturing, familiar with (i) cholesteric liquid-crystal circular-polarization separation films, (ii) crossed-analyzer/depolarization inspection, and (iii) standard angle-dependent retardance measurement (Re/Rth by oblique incidence).

3. Prior art of record

4. Element mapping

5. Combinations that render the claims obvious

Combination A (primary — transmissive method, claim 1 et al.): D1 + D4/D5, optionally + D3. D1 discloses the complete architecture, the cholesteric CP-separation films, the transparent-film target, and the polarization-selectivity logic. The only missing limitation is the tilt angle. D4 supplies express oblique-incidence polarized inspection; D5 and D2's own Rth practice supply the geometry. Rationale: to detect a low-birefringence transparent film (the patent's own TAC example, Re≈0/Rth≈100 nm), a PHOSITA must generate a measurable polarization change. At normal incidence a film with Re≈0 produces essentially no net depolarization; tilting increases the optical path length through the film and brings the out-of-plane retardance (Rth) into play, producing a nonzero, angle-dependent effective retardance that converts a fraction of the incident circular polarization to the orthogonal sense. This is a predictable, first-order optical result — exactly the mechanism the '588 specification recites ("it is possible to increase a distance by which the light passes through a target object, substantially increase a thickness, and increase birefringence"). Motivation thus exists in the problem itself, before any reference is consulted. (Corroborative but likely not prior art: US 2019/0120617 A1 expressly states that for a 10–30% transparent workpiece "increasing the length … through which the light passes advantageously increases the sensitivity," using a "shallow angle." Its 2019 publication date appears to post-date the 2015-04-24 priority date, so I flag it as non-art corroboration only unless its effective filing date is verified.)

Combination B (method, reflected-light and double-pass variants): D2 (claim 1 reflection variant) + D3 + D4, with D1 for the transparent-product substitution. D2 already teaches the complementary reflection geometry, and D3 teaches that swapping linear for circular polarization removes the analyzer-alignment burden. The "same sense" (reflection) / "opposite sense" (transmission) requirement is not an inventive selection — it follows directly from the handedness-conservation of specular reflection and the handedness-reversal/depolarization on transmission; a PHOSITA sets the analyzer accordingly as a matter of course, just as D2's two claim variants were set.

Combination C (system claims): D1 + D4/D5. The system claims are the apparatus counterpart of Combination A; D1 is a system disclosure (emission unit, target/movement, detection unit, CP separation films), so the tilt geometry is the only addition. Notably, the ISR for the EP family member (EP 3 171 156 A1) found a system claim lacking novelty over two cited documents — evidence the architecture itself was not novel, reinforcing that validity, if any, rides entirely on the angle range.

Dependent-claim issues: the cholesteric-film limitations are anticipated by D1 (its entire premise is a cholesteric CP separation layer), and the multi-emitter/planes-of-incidence features are routine optimization of sampling geometry — though I found no specific anticipatory reference for the multi-emitter feature in this session, so that limitation carries the strongest (if not generous) non-obviousness argument: the patent reports 330.1% (one azimuth) → 6,784.5% (two) → 10,097.5% (three), which is not linear and could be argued as synergistic. That argument only helps if the multi-emitter feature is actually claimed as a limitation and if the applicant can show the effect is attributable to the claimed combination rather than to the mere accumulation of independent samples.

6. Why the 20°–70° range does not rescue the claims

• Result-effective variable / routine optimization. The specification gives no data at the 20° or 70° boundaries; it tests only 0°, 35° and 60° (Examples 1–6 and Comparative Examples 1–7). Preferred sub-ranges (25°–65°, 30°–62°) are recited without any criticality showing. That is the paradigm of a range optimized by routine experiment.
• The disclosed effect is exactly what optics predicts. The jump from ~110% (0°) to 2921% (60°) tracks the 1/cos θ path-length increase plus the sin²θ-weighted Rth contribution. No unexpected result is established.
• No teaching away. D1's emphasis on suppressing ambient light argues for shielding (the '588 spec adopts housings for that purpose) — it does not disparage tilting.

7. Anticipated rebuttals and secondary considerations

1. "D1 does not disclose a transparent product" — the specification's own background concedes the opposite ("WO 2014/181799 … discloses the sensing of a target object using a transparent film").
2. Criticality / unexpected results — unavailable on this record (see §6).
3. Non-analogous art (D4, wafer inspection) — weak: D4 is from the same field of endeavor (optical inspection by polarization-state analysis) and is reasonably pertinent to the problem of illuminating a specimen obliquely with polarized light; KSR and In re Bigio favor considering it.
4. Secondary considerations — nothing in the record (no nexus evidence, no licensing, no copying, no long-felt-need showing). Any long-felt-need argument is further weakened because D1 is the same applicant's own earlier work (Fujifilm), making the '588 patent an incremental in-house improvement rather than a solution to a recognized industry failure.
5. § 102(a)(2) posture of the US-family references — US 2016/0054496 A1 and US 9,671,540 B2 are Fujifilm documents; their availability depends on effective filing dates relative to 2015-04-24, and § 103(c) common-ownership disqualification could be invoked against the § 102(a)(2) branch (it does not remove them as § 102(a)(1) printed publications if their publication predates 2015-04-24). These dates must be verified before relying on those two documents.

8. Residual uncertainty (stated explicitly)

• Claim numbering is unresolved and the earlier sections contradict each other and the chart data (§1). Cite the angle limitation by element, not by number, until the granted claims are pulled from USPTO Patent Center.
• I could not independently verify the full text of JP 2008-58270 A or JP 2013-36888 A beyond their abstracts/characterizations and the third-party summaries (US 2016/0054496 ¶[0006]; US 9,671,540; the EP 3 171 156 ISR). The Japanese-language texts should be obtained and confirmed, especially whether D2/D3 disclose any oblique geometry.
• I could not verify D1's (WO 2014/181799) specification for any statement of incidence angle; if D1 does disclose or suggest oblique incidence onto the moving film, claim 1 becomes a § 102 anticipation rather than a § 103 combination.
• The family relationship US 15/790,350 ↔ WO 2016/171218 ↔ EP 3 171 156 A1 is inferred from matching cited references (JP2008-58270A / JP2013-36888A) and subject matter, not confirmed from the EP front page in this session.
• No litigation, PTAB or CAFC activity was found in the prior section; that does not affect the merits analysis above.

9. Bottom line

Under KSR, claims 1–15 of US 10,598,588 are, on the record available, vulnerable to a § 103 rejection built on D1 (WO 2014/181799) as the primary reference, in view of oblique-incidence polarized inspection art (D4: US 2010/0014075 / EP 2 287 594 / US 9,019,498; D5: the Fujifilm CP-filter art) and, for the method variants, D2 + D3 (JP 2008-58270 A + JP 2013-36888 A). D1 supplies every limitation except the >20°–70° angle; that angle is a result-effective variable whose benefit (longer path length, activated Rth) is predictable from elementary optics and is expressly recited in the specification's own stated rationale, with no criticality data and no teaching away. The cholesteric-film claims fall with D1 alone; the "opposite-sense transmission / same-sense reflection" claims fall on inherent physics and the D2/D3 linear-polarizer analogue. The one genuinely arguable limitation is the multi-emitter / multiple planes-of-incidence feature, which relies on a synergy argument rather than on reference disclosure.