US 5680104

I'll search for the specific patent number and any related litigation activity.

Let me check specifically for litigation activity involving this patent.

US Patent 5,680,104 — Search Results and Summary

A note on method and my limitations: I ran targeted web searches for the exact number 5680104 / 5,680,104. My tooling is general web search (which surfaced Google Patents, Justia, EveryPatent, and Google's citation graphs), not authenticated access to USPTO PatentCenter/PTAB or the Federal Circuit's docket system. So I can report what surfaced, but I cannot certify a negative for litigation records. I did not auto-correct any identifier, and I found no evidence of any other patent number being confused with this one.

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Bibliographic data (verified against the Google Patents record)

The assignment document lists the assignors in the order "LAFFERTY, MICHAEL WILLIAM; DIAMOND, E. ANTHONY; SLEMON, CHARLES S." — the name-element ordering differs from the Google Patents inventor listing, but these are the same three individuals.

Abstract (as published)

An optical fiber security system includes an optical emitter connected to one end of an optical fiber and a detector connected to the other end. A random signal generator triggers the emitter to output a light pulse signal through the fiber. This generator also simultaneously triggers the detector to receive the light pulse signal. A comparator compares the light pulse signal that is received by the detector with an optimum reference to adjust and conform the emitter output with the reference. Also, a monitor determines whether a particular identifiable characteristic of the light pulse signal is within a predetermined range of values. Whenever there is not a simultaneous emission and detection of the light pulse signal, or whenever the light pulse characteristic is outside the predetermined range of values, the system alarms.

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Independent claims — plain-language overview

The patent has 21 claims total, of which two are independent: claim 1 (apparatus) and claim 18 (method).

Claim 1 — Apparatus ("optical security system")
Requires five elements:

1. An optical fiber with a first end and a second end.
2. An emitter optically connected to the first end.
3. A detector optically connected to the second end.
4. A signal generator that triggers both the emitter and the detector: the emitter transmits a pulse having at least one identifiable characteristic into the fiber, while the detector is simultaneously triggered to receive that pulse as it exits the far end. (The synchronous, in-phase detection theme.)
5. Two downstream functions: (a) a comparator that compares the received pulse to a predetermined reference and outputs a correction that adjusts the emitter so a subsequent pulse conforms to the reference (closed-loop feedback/ALC); and (b) a monitor on that characteristic that alarms when the received pulse "passes a predetermined threshold."

Notably, claim 1 itself recites only "means for generating a signal" — the word random appears in the specification and in independent method claim 18, but not in apparatus claim 1. Dependent claim 4 supplies the bi-directional (high/low threshold) limitation.

Claim 18 — Method ("for arming a security system incorporating an optical fiber")
Mirrors claim 1 in method form, but adds the randomness explicitly:

1. Generate a random signal.
2. Simultaneously trigger an emitter and a detector with that random signal — the emitter transmits a light pulse with at least one identifiable characteristic through the fiber, and the detector is positioned/triggered to receive it.
3. Compare the received pulse to a predetermined reference to adjust the emitter so a subsequent pulse conforms to the reference.
4. Monitor that characteristic and alarm when the received pulse passes a predetermined threshold.

Dependent claims 19–21 add tolerance for "predetermined minor deviations," the high/low threshold band, and the characteristic list (amplitude, frequency, phase, wavelength, pulse width, or polarity).

Dependent-claim coverage (1→17): emitter = LED (2), detector = photodiode (3), high/low threshold alarm band (4), monitored characteristic = amplitude (5), frequency (6), phase (7), wavelength (8), pulse width (9), "polarity" (10), optical-noise injection (11), closed-loop feedback/adjustable time response in the comparator (12–14), multipliers gating the emitter and the detector against the generator signal (15–16), and added shot noise (17). Two multipliers are claimed separately — one between generator/comparator/emitter and one between generator/comparator/detector.

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Litigation / Federal Circuit docket check

Searching for a 2026 CAFC docket or infringement suit involving this patent returned no results. I want to flag the practical reason: the patent's legal-status record shows it expired in 2001 for failure to pay maintenance fees under 37 CFR 1.362 (maintenance-fee reminder mailed 2001-05-15; lapse 2001-10-22; expiration recorded 2001-11-27). An expired patent cannot support a 2026 infringement action, so the absence of a 2026 docket entry is consistent with the record rather than surprising. That said, I cannot rule out unrelated uses of the string "5680104" (e.g., my second query incidentally returned a Brazilian state-registry filing number 5680104 for an unrelated food company — a coincidental numeric match, not this patent).

Uncertainty statement: I do not have authoritative, direct-query access to PatentCenter, PTAB, or the CAFC CM/ECF docket in this session, so treat "no litigation found" as absence of evidence from general web search, not a verified negative.

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Additional context from the citation record

• Prior art cited on the face of the patent (8 U.S. refs): US3488586 (Gen Electric), US3742947 (American Optical), US3794841 (Cosentino), US3986498 (Videodetics), US4589404 (Medical Dynamics), US4870952 (Martinez), US4878045 (Honda Giken Kogyo), US4812641 (General Electric). Notably, several are medical-optics or data-link references rather than security references.
• This patent is itself cited by later fiber-optic security work, including US7135970 (DSFE Security Systems International, 2006), which expressly criticizes US5680104 as requiring "a complicated feedback loop of electronic components" that makes it "unnecessarily inefficient, complicated and expensive," and notes it "describes a portable system." US7135970 then claims a simplified single-signal approach.
• Family: Single-member family — no non-US siblings in the Google Patents data; only one application claims priority (US08/652,913).

One literal-reading caveat worth preserving: dependent claim 10 recites the characteristic as "a polarity," whereas the specification's characteristic list says "polarization." These are different technical concepts, and under the instruction not to auto-correct identifiers/terms, I am reporting the claim language exactly as issued rather than harmonizing it with the description.

I'll search litigation databases for US patent 5680104.

Let me try more targeted litigation-specific searches.

US Patent 5,680,104 — Litigation Search Results

Bottom line: I found no record of any litigation involving US Patent 5,680,104. No district court case, no ITC proceeding, no PTAB challenge (IPR/PGR/CBM), and no Federal Circuit appeal could be located that names this patent.

What I searched

• General web searches for the patent number both with and without commas ("5680104" / "5,680,104") combined with litigation/ infringement/ lawsuit terms
• Searches for Volution Inc. (the original assignee) in connection with patent litigation
• The Unified Patents litigation portal domain, and litigation/PTAB-document sources (courtlistener, PTAB petition filings)
• The Google Patents family/litigation page for the patent, which lists no "Litigation" or "PTAB" entries

None of these returned a hit tying the number 5,680,104 to any docket. Search results that mentioned other case numbers (e.g., NantWorks/Bank of America, Certicable/P2P, Panduit/Corning) concerned entirely different patents and are unrelated.

Context that explains the absence (from the patent record itself, not from litigation)

The absence of litigation is consistent with the patent's prosecution and lifecycle history as shown on the Google Patents record:

The patent was in force for only about four years (Oct. 1997 – Oct. 2001) before lapsing for nonpayment of the first maintenance fee. Its legal status is listed as "Expired – Fee Related," and the anticipated expiration date shown is 2016‑05‑31 (had fees been paid). A four‑year enforcement window in a narrow technical niche for a small assignee ("Volution," now shown as "Volution Inc") makes the absence of recorded enforcement unsurprising.

Important caveats

• I could not directly load the Unified Patents litigation case‑list page or PACER; my access was through search results and the Google Patents page, which returned no case entries for this number.
• Coverage of very old or very short‑lived enforcement campaigns is imperfect in free databases. A negative result here means no litigation is publicly recorded in the sources I could reach, not a categorical guarantee that no suit ever existed.
• If you need a definitive clearance‑style answer, the authoritative check would be a paid full‑text docket search (e.g., Docket Navigator, Lex Machina, or a PACER/ITC full‑text query) plus the USPTO Patent Assignment and Trial (PTAB) databases.

If you'd like, I can draft the litigation‑summary section of your analysis as an explicit "No litigation found" statement with the search methodology and limitations stated for the file, suitable for inclusion alongside the previously prepared sections.

PTAB Proceedings Analysis — US Patent 5,680,104 ("Fiber optic security system")

Prepared 2026-09-30 by a senior PTAB practitioner. Sources: USPTO Open Data Portal "PTAB proceedings on file" block (provided), Google Patents docket for US5680104A, and web searches run for this task.

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Proceedings overview

Total AIA trial proceedings on file: 0 (zero) — zero active, zero claims invalidated, zero claims sustained, zero settled, zero institution denials. The USPTO ODP API returns no AIA trial proceedings for US 5,680,104, and my web searches surfaced no IPR/PGR/CBM petition, institution decision, Final Written Decision, or Federal Circuit appeal naming this patent. The bottom-line defensive posture is unusual and — for a defendant — extremely favorable on grounds wholly independent of PTAB: this patent did not just survive or get narrowed, it died of fee non-payment in 2001, less than four years after it issued. It is public domain. No IPR was ever needed, and none was ever filed.

Because the structured block is empty and my searches found nothing, I will not fabricate proceeding numbers, panels, or claim-level outcomes. Where the template calls for per-proceeding detail, I explain below why each field is inapplicable.

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Per-proceeding sections

None exist. There is no proceeding to list, so the "most-impactful first" ordering has no entries. Confirmations performed:

• ODP / PTAB structured data: "The USPTO ODP API returns no AIA trial proceedings for this patent as of the most recent ingest." (canonical source for this task)
• Web search — US 5680104 PTAB inter partes review Volution fiber optic security system: returned only the Google Patents text and EveryPatent abstract; no PTAB or trial documents.
• Web search — "5680104" IPR petition Patent Trial and Appeal Board: zero results.
• Web search — "5,680,104" patent lawsuit Volution fiber optic security asserted: zero results.
• Web search — US5680104 Federal Circuit appeal patent: returned an unrelated PTAB petition (a treadmill patent matter, IPR petition 1553929), not this patent. No CAFC appeal for '104 appears anywhere.

Chronological reason no AIA trial exists: AIA trial practice (IPR/PGR/CBM) began on 2012-09-16. This patent was filed 1996-05-31, issued 1997-10-21, and lapsed on 2001-10-21 for failure to pay maintenance fees — more than a decade before the AIA created these proceedings. There was never a window in which an AIA petition against a live '104 patent could have been filed.

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Prosecution, expiry, and prior-art landscape (context a defendant actually needs)

Even without PTAB activity, the record that does exist is decisive:

• Original assignee / current assignee: Volution Inc (per Google Patents; listed assignees may be incomplete).
• Inventors: Charles S. Slemon, William Michael Lafferty, Anthony E. Diamond. Assignment to Volution recorded 1996-07-18 (REEL/FRAME 008041/0262; effective 1996-05-30).
• Terminal events (Google Patents "Legal Events"):
  • 2001-05-15 — Maintenance fee reminder mailed.
  • 2001-10-22 — Lapsed for failure to pay maintenance fees.
  • 2001-11-27 — "PATENT EXPIRED DUE TO NONPAYMENT OF MAINTENANCE FEES UNDER 37 CFR 1.362."
  • 2001-12-25 — Lapsed due to failure to pay maintenance fee; effective date 2001-10-21.
  • Status now reads: Expired - Fee Related; anticipated expiration listed as 2016-05-31 (the nominal 20-year date from the 1996 filing) but the patent did not reach it.
• Claims: 21 total (claims 1–21), with claim 1 the sole system independent claim, claim 18 the independent method claim, and dependent claims 2–17 and 19–21.
• Prior art cited on the face of the patent (8 references): US3488586 (Gen Electric, 1970), US3742947 (American Optical, 1973), US3794841 (Cosentino, 1974), US3986498 (Videodetics, 1976), US4589404 (Medical Dynamics, 1986), US4812641 (General Electric, 1989), US4870952 (Martinez, 1989), US4878045 (Honda Giken Kogyo, 1989).
• Forward citations: Google Patents shows the patent as "Cited By" 19–33 documents, including WO2001039148A1 (Future Fibre Technologies), US7135970B2 (DSFE), WO2017011261A1 (3M), and the CyberSecure IPS family — i.e., the '104 disclosure is background art against later fiber-optic tamper systems, which further confirms it is treating as expired prior art rather than a live asserted patent.

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Strategic summary

Cancelled vs. sustained vs. untested. For AIA purposes the set is empty: no claim of '104 was ever the subject of an institution decision, an FWD, or an affirmed cancellation. But the practical status is stronger than "sustained" — the entire patent (claims 1–21) is expired and unenforceable because maintenance fees lapsed effective 2001-10-21, and the right to enforce was not revived. A defendant today faces no live infringement exposure on claims 1–21; every claim is spent. The only residual role of '104 is as prior art (an anticipatory/obviousness reference with a 1996-05-31 priority date) — as it is used, for example, against later tamper-detection applications at the EPO/PCT.

Estoppel landscape. There is no § 315(e)(2) estoppel of any kind — estoppel arises only from a petitioner's participation in an AIA trial that reaches a final written decision, and no such trial exists. Conversely, there is no defensive benefit from an earlier petitioner's invalidity win either, because there was none. If a party were somehow confronted with a theory keyed to an issued-but-expired claim (e.g., a damages period predating 2001-10-21, or an accusation that mischaracterizes the patent as in force), the defense is not PTAB estoppel but laches/limitations, expiration, and the public-domain status of the disclosure; the prior art cited on the face of the patent, plus the lapse event, are the operative facts.

Pattern signals. None to read. No recurring petitioner (no Unified Patents, no aggregator, no serial challenger appears in the record); the patent owner never pursued a PTAB appeal because no PTAB proceeding existed to appeal; and the CAFC docket shows no '104 appeal. The patent's owner-of-record never even kept it alive past the first maintenance-fee window — the classic profile of a patent that was never commercially asserted after issuance.

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Recommended next steps

• If you are a defendant or recipient of a demand letter citing US 5,680,104: the dispositive facts are the expiry events, not PTAB. The patent lapsed effective 2001-10-21 and expired for non-payment of maintenance fees (37 CFR 1.362), reflected in the Google Patents docket at https://patents.google.com/patent/US5680104A and the USPTO assignment/legal-events record. Demand letters that treat claims 1–21 as enforceable should be rebutted head-on: the asserted claims have been unenforceable for roughly a quarter century, and only pre-lapse damages (if any survived the statute of limitations) could ever be at issue. There is no FWD to link or quote — be suspicious of any assertion that one exists.
• If you were hoping to rely on an existing IPR to invalidate the claims: understand that this is not the fact pattern. There is no prior petitioner, so there is no institution record, no claim-construction ruling, and no estoppel you can borrow. If a live dispute nonetheless requires an invalidity position (e.g., a collateral challenge to the patent's teaching as prior art), you build it from scratch using the eight references cited on the patent's face and the 1996-05-31 effective filing date.
• Milestones to calendar: none — there is no pending proceeding with an institution-decision deadline, oral hearing, or statutory one-year FWD deadline. The absence of any PTAB activity here is not the "well-asserted patent that escaped IPR" signal; it is the "patent that was allowed to expire before the IPR era began" signal, and for a defendant that is the strongest possible posture.

Constraint check: No proceeding number, judge panel, ground, settlement term, or claim-level holding is asserted as fact because none exists in the record; the structured ODP block was empty and my searches corroborated that. Everything above is anchored to the patent's own docket, citations, and the legal-events record.

I'll verify the assignment record and the original assignee's history before writing up.

Ownership & Assignment Analysis — US 5,680,104 "Fiber optic security system"

Analyst note on sourcing / limits: I could not render the Assignment Center UI directly with the tools available in this session. The chain below is reconstructed from (a) the USPTO assignment data as mirrored in the Google Patents legal-events record for this patent, (b) the reel/frame string printed in the assignment abstract itself (REEL/FRAME:008041/0262), and (c) the patent front-matter/agent of record. Where the Assignment Center exposes fields (e.g., correspondent of record) that are not carried in those mirrors, I say so rather than filling the gap.

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Inventors

Pattern notes:

• The assignment was executed 1996-05-30 — one day before the 1996-05-31 filing date — i.e., a routine all-inventors-assign-to-employer instrument signed at filing. This is not the "inventors depart within 12 months" fire-sale precursor the brief asks about, and there is no recorded evidence any inventor left before the assignment.
• Slemon is the apparent repeat inventor behind the corporate vehicle: he is the named inventor on earlier optical-security art in the same technical family (e.g., US 5,049,855, "Security screen system," priority 1989-10-24, granted 1991-09-17), which indicates Volution was a home for an inventor's own security-product line, not a holding shell. (Assignee of US 5,049,855 not confirmed in this session — do not rely on that sub-point.)
• All three inventors assigned simultaneously in a single instrument (one reel/frame, three assignors). No later inventor-side instruments exist in the record.

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Original assignee

Volution / "Volution Inc," California. Named as applicant and assignee on the face of the patent; the assignment legal event records assignee address as simply VOLUTION, CALIFORNIA.

• Product embodiment: The specification is written as a buildable, manufacturable system (LED emitter, photodiode detector, RC averager ≈0.01 s, ALC feedback loop, bi-directional monitor with high/low thresholds, alarm gate) and expressly describes installation on real objects (FIG. 1: box frame 20, pole 22). The claimed subject matter (claim 1: fiber + emitter + detector + random trigger + comparator + threshold monitor) maps directly onto that apparatus. Read against Slemon's prior optical-security work, Volution appears to have been an operating security-hardware company, not a licensing vehicle, at the time of filing.
• Primary line of business: fiber-optic security / intrusion-detection barriers.
• Current status: Not determinable from this record. No merger, change-of-name, dissolution, or bankruptcy instrument was ever recorded against this patent. What is documented is that Volution stopped paying to keep the patent alive (see below), and there is no public evidence of an acquisition of this IP.
• Prosecution agent of record: the application was handled by Nydegger & Associates (per patent-office front-matter/agent data). This is the prosecution correspondent, not confirmed as the assignment-recording correspondent.

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Assignment timeline

Exactly one assignment is recorded against US 5,680,104. After that, the only legal events are maintenance-fee lapses.

• 1996-05-30 (executed) / recorded 1996-07-18 — Reel 008041/0262
  • Conveyance: ASSIGNMENT OF ASSIGNORS INTEREST (see document for details)
  • Assignor: LAFFERTY, MICHAEL WILLIAM; DIAMOND, E. ANTHONY; SLEMON, CHARLES S. (three joint inventors)
  • Assignee: VOLUTION, California
  • Correspondent: Not exposed in the assignment legal-event record available to me. I will not invent a name here. The only firm associated with this file is the prosecution agent Nydegger & Associates; whether that firm also filed the 1996 recording is unverified. No recurrence flag can be raised from a single, unconfirmed correspondent entry.
  • Context: inventor-to-employer assignment at filing — capture of rights by the company, not an acquisition, securitization, or transfer to a third party.

Terminal events (not conveyances, but they determine who owned the patent when it died):

• 2001-05-15 — Maintenance-fee reminder mailed.
• 2001-10-22 — Lapse for failure to pay maintenance fees.
• 2001-11-27 — Patent discontinued: "PATENT EXPIRED DUE TO NONPAYMENT OF MAINTENANCE FEES UNDER 37 CFR 1.362."
• 2001-12-25 — Lapsed due to failure to pay maintenance fee; effective 2001-10-21.
• 2016-05-31 — Anticipated 20-year expiration date (nominal; the patent had already been dead for ~15 years).
• Google Patents current status: Expired – Fee Related.

Reading of the chain: there is no post-issuance transfer of any kind. Volution (or whatever it became) held the patent from 1996 until the 4-year maintenance fee went unpaid in 2001, at which point the asset entered the public domain. The patent, in other words, was abandoned by its owner, not asserted or sold.

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Timeline diagram

timeline
    title Ownership of US 5680104
    1996 : Inventors assign rights to Volution Inc
         : Application filed on 31 May 1996
    1997 : Patent issues as US 5680104 on 21 Oct
    2001 : Maintenance fee unpaid and patent expires
    2016 : Nominal 20 year term would have ended

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NPE / troll-pattern signals

1. Shell-entity transfer — not present. The only conveyance (reel 008041/0262, executed 1996-05-30) runs from three named individual inventors to an operating security company. There is no downstream transfer to any "IP / Patents / Licensing / Holdings / Ventures" entity, no registered-agent-service address, and no single-purpose LLC anywhere on the record.

2. Known asserter in the chain — not present. The assignee of record is Volution (California) and no subsequent assignee exists. No match to Acacia, Marathon, Intellectual Ventures, IPNav, Wi-LAN, Mosaid/Conversant, Vringo, Pendrell, Innovatio, MPHJ, Lumen View, Round Rock, Erich Spangenberg entities, or any RPX/Unified high-frequency-plaintiff listing appears in the record. The 19 "Cited By" families (e.g., Future Fibre Technologies, Cisco, Network Integrity Systems, CyberSecure IPS, Titan Photonics) are forward citations only — they are not assignees of this patent and must not be read as chain links.

3. Repeat correspondent across the chain — not present / not assessable. With only one recorded instrument, recurrence is structurally impossible to detect here. The recording correspondent for reel 008041/0262 is not surfaced in the data I can reach; the only attorney/firm attributable to this file at all is Nydegger & Associates as prosecution agent. One appearance is explicitly not a finding under the brief's own rule.

4. Cascading transfers — not present. Zero consecutive assignments, let alone multiple LLC-to-LLC hops in <24 months. The chain is a single link plus a fee lapse.

5. Pre-litigation transfer — not present. No infringement suit naming this patent was located in the searchable record. There is no assignment within 6 months (or any period) before any such suit, because there is no post-issuance assignment and no suit.

6. Bankruptcy fire-sale — not present. No Chapter 7/11 instrument, no trustee's sale, no court-ordered transfer recorded. Non-payment of a maintenance fee is an abandonment, which is the opposite of a fire-sale: nothing was sold because nothing was worth buying.

7. Privateering — not present. No operating company → NPE transfer; no SEC disclosure located; no assertion activity of any kind.

8. Defensive aggregator (anti-NPE) — not present. The chain does not terminate at RPX, AST, LOT, Unified, or OIN. The neutralization here was accomplished by statutory expiration from non-payment, not by defensive acquisition.

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Verdict

Insufficient data (only the original assignment).

Justification: The complete recorded chain is a single inventor-to-employer assignment — executed 1996-05-30, recorded 1996-07-18 at reel 008041/0262, with Volution (California) as assignee — and it is followed by no conveyance whatsoever. Instead, the record closes with the 2001-05-15 maintenance-fee reminder and the 2001-10-21/2001-11-27 lapse under 37 CFR 1.362, meaning the patent was abandoned by its original owner and has been in the public domain since 2001; there is no current assignee, no litigation, and no asserter directory hit to analyze. There is therefore no evidence-based basis to call this an NPE chain, and equally no "operating-company assertion" finding, since no assertion ever occurred.

Verify at:

• USPTO Assignment Center search for patent 5680104: https://assignmentcenter.uspto.gov/ (also https://assignment.uspto.gov/patent/index.html)
• Google Patents legal events: https://patents.google.com/patent/[US5680104A](/patent/US5680104A)/en#legalEvents
• Reel/frame to pull: 008041/0262

Caveat worth flagging for the file: the absence of an Assignment Center correspondent of record in the material I could retrieve means signal #3 is unproven rather than disproven. If you can pull the reel 008041/0262 cover sheet directly, the recording attorney/firm on that single instrument is the one field still open. Given the 2001 abandonment, however, resolving it is unlikely to change the verdict.

I'll research each cited reference and verify details against available sources.

I hit a step-budget limit before I could individually verify the last three references, so I'll flag that explicitly below rather than invent detail. Here's my analysis.

Prior-Art Analysis for US 5,680,104 ("Fiber optic security system")

Scope and method caveat

• Authoritative source for the citation list is the patent's own front-page "Patent Citations (8)" table (all eight appear to be examiner citations, per the "cited by examiner" annotation), cross-checked against Google Patents / uspto.report where search results were returned.
• Confidence flags: Full text/claims were retrieved for US 3,488,586; US 3,742,947; US 3,794,841; US 3,986,498; and US 4,812,641. For US 4,589,404; US 4,870,952; and US 4,878,045 I was only able to confirm the bibliographic data already in the patent's citation table plus title-based subject matter — I mark those below as not independently verified.
• Today's task date is given as April 26, 2026; the earlier summary section used a 2026-09-30 date. That inconsistency does not affect the prior-art analysis (all references predate the 1996-05-31 priority date by decades).

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The eight cited references — summary table

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Reference-by-reference detail and § 102 mapping

1. US 3,488,586 A — "Frequency modulated light coupled data link" (Gen Electric; filed 1965-06-02; issued 1970-01-06)

Description (verified): A wide-range remote-control data link. A light-emitting diode (LED) transmits modulated light pulses through an optical path to a light-optic receiver; an analog-to-frequency converter and pulse generator drive the LED, and the receiver demodulates the pulses. Explicitly motivated by overcoming analog-transmission calibration problems by using pulsed light.
§ 102 mapping: Discloses the emitter (LED) and pulse-transmission elements. Directly relevant to claim 2 (emitter is an LED) and, arguably, the "pulse having at least one identifiable characteristic" language of claim 1. It does not, standing alone, anticipate claim 1 or claim 18, because it lacks (a) an optical fiber with first/second ends, (b) a detector simultaneously triggered by the same signal generator (synchronous in-phase detection), and (c) the comparator/adjust-emitter feedback loop. Best characterized as § 102 art against claim 2 and as § 103 art against the pulse-transmission concept of claim 1.

2. US 3,742,947 A — "Optically isolated electro-medical device" (American Optical Corp.; filed 1971-08-26; issued 1973-07-03; inventor James F. Hashem)

Description (verified): Patient-monitoring device using optical coupling for electrical isolation. A light-emitting diode is modulated by the amplified patient signal and drives light into a photo-transistor, which recovers the signal on the isolated side. Focus is electrical safety, not intrusion detection.
§ 102 mapping: Anticipates the emitter = LED limitation (claim 2) and discloses an optical emitter/detector pair. Its detector is a phototransistor, not a photodiode, so it does not anticipate claim 3. It contains no fiber, no synchronous dual-triggering, no comparator-feedback — so claim 1 / claim 18 are not anticipated.

3. US 3,794,841 A — "Light coupling data transfer system" (L. Cosentino; filed 1972-07-25; issued 1974-02-26)

Description (verified): A light-coupled isolation system transmitting patient-derived data. A comparator (13) and integrator (14), plus a low-pass filter (15), drive a push-pull switching stage that on/off-drives an optical isolator; the patient data modulates the zero crossings of a higher-frequency constant-amplitude waveform, and a demodulator recovers the information.
§ 102 mapping: Most relevant to the phase characteristic (claim 7) — zero-crossing modulation is a phase-timing technique — and it discloses a comparator in the signal chain. But its comparator forms a local modulator loop, not the claimed "compare received pulse with a reference to adjust the emitter" architecture, and it is not a security system over an optical fiber. No anticipation of claim 1 or claim 18; at most § 103 support for the comparator/phase concepts.

4. US 3,986,498 A — "Remote ECG monitoring system" (Videodetics Corp.; filed 1975-09-08; issued 1976-10-19)

Description (verified): Hospital telemetry in which a battery-operated patient unit FM-transmits baseband ECG; a receiver/retransmitter re-modulates and injects the signal onto the existing master-antenna TV (MATV) coaxial cable for central monitoring. It is a radio/RF telemetry system, not an optical-fiber barrier.
§ 102 mapping: Weakest of the eight. It discloses multi-patient telemetry and monitoring at a central station but nothing about an optical fiber, an emitter/detector pair on the fiber, synchronous random triggering, or a threshold monitor on a light-pulse characteristic. Does not anticipate any of claims 1–21. Its presence in the citation list is best explained as general "monitoring/telemetry system" art.

5. US 4,589,404 A — "Laser endoscope" (Medical Dynamics, Inc.; filed 1984-01-03; issued 1986-05-20) — not independently verified

Description (from title/bibliography): A laser endoscope, i.e., an instrument using a laser and optical fiber to deliver illumination/energy in a medical procedure.
§ 102 mapping: Discloses laser + fiber energy delivery in a medical context. It does not disclose a security barrier, a random signal generator, synchronous detection, or a two-threshold alarm monitor. No anticipation of claim 1 or claim 18. Because I could not verify its full disclosure, treat any beyond-title inference as provisional.

6. US 4,812,641 A — "High power optical fiber failure detection system" (General Electric Co.; filed 1987-02-03; issued 1989-03-14; inventor Angel L. Ortiz Jr.)

Description (verified — the most technically on-point citation): An industrial laser materials-processing system with a fiber break/leak detector. A first photodetector senses the laser power injected at the input coupler; a second photodetector senses the power exiting the output coupler. Electronics compare the input and output power levels; a decrease in output (relative to input) that exceeds a set threshold indicates a break/leak and triggers laser shutdown. The stated goal is a failsafe interlock before damage.
§ 102 mapping: This is the closest structural analogue to parts of independent claim 1: it has an optical fiber with an input and output, a light emitter (laser) at one end, detectors at the ends, and a comparator with a threshold that trips an alarm/shutdown. It therefore maps onto the generic fiber + emitter + detector + comparator + threshold-monitor skeleton and is relevant to claim 5 (amplitude) monitoring. However, it critically lacks: (a) a single signal generator that simultaneously triggers both emitter and detector for synchronous in-phase detection; (b) the random pulse characteristic; and (c) a feedback output that adjusts the emitter to conform a subsequent pulse to the reference. So claim 1 is not anticipated (all elements required for § 102), but US 4,812,641 is strong § 103 art against the fiber-and-detector/comparator/threshold portions of claim 1 and against claim 5.

7. US 4,870,952 A — "Fiber optic illuminator for use in surgery" (Miquel Martinez; filed 1983-10-28; issued 1989-10-03) — not independently verified

Description (from title/bibliography): A fiber-optic illuminator for surgical use.
§ 102 mapping: Fiber-optic light delivery in a medical context only. No security monitoring, no synchronous detection, no threshold alarm. No anticipation of claims 1–21.

8. US 4,878,045 A — "Locking cable for antitheft devices" (Honda Giken Kogyo K.K.; filed 1984-12-27; issued 1989-10-31) — not independently verified

Description (from title/bibliography): A mechanical locking cable used in antitheft devices — i.e., the conventional "line/connector linking an object to a stable anchor" technology described in the '104 background as the prior art the invention improves upon.
§ 102 mapping: Relevant only to the field/background (the mechanical security-cable art), not to any optical element. It cannot anticipate claim 1 or claim 18, each of which requires an optical fiber, emitter, detector, and dual-triggering generator. No anticipation of any claim.

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Bottom line on § 102

• No single cited reference anticipates independent claim 1 or independent claim 18. Each of the two independent claims requires the combined elements of: an optical fiber with two ends; an emitter and a detector on opposite ends; one signal generator that simultaneously triggers both the emitter and the detector; a comparator that adjusts the emitter to conform a subsequent pulse to a reference; and a monitor that alarms when a pulse characteristic passes a threshold. No cited reference discloses the synchronous dual-triggering / in-phase detection element at all, and this is the acknowledged novelty driver of the patent.
• Anticipation candidates exist only at the dependent-claim level, and even there they are partial:
  • Claim 2 (emitter = LED): anticipated-ish by US 3,488,586 and US 3,742,947 (both expressly disclose an LED emitter).
  • Claim 5 (amplitude monitoring): US 4,812,641 discloses amplitude/power-level comparison against a threshold.
  • Claim 7 (phase): US 3,794,841 (zero-crossing/phase-based modulation) is pertinent but in a non-analogous isolation context.
• US 4,812,641 is the most relevant single reference for a § 103 combination, because it is the only citation that combines an optical fiber, end-mounted emitter/detector(s), a comparator, and a threshold-triggered shutdown. Combined with an LED-teaching reference (US 3,488,586 or US 3,742,947), it could be asserted against the fiber/detector/comparator/threshold portions of claim 1 — but the synchronous random dual-triggering limitation would still need separate art.

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Important observation: more relevant art sits in the "Similar Documents" list, not the citation list

The Google Patents record for US 5,680,104 lists several documents under "Similar Documents" that are far more on-point to a fiber-optic security invention than most of the eight examiner citations:

• US 5,005,292 — "Fiber optic security system for protecting equipment from tampering"
• US 5,055,827 — "Fiber optic security system"
• US 4,292,628 — "Fibre optic security system"
• US 4,577,184 — "Security system with randomly modulated probe signal"
• US 5,198,799 — "Opto-electronic security fence"

US 4,577,184 in particular (randomly modulated probe signal) and US 5,055,827 / US 4,292,628 / US 5,005,292 (fiber-optic security systems) are, on their face, potentially the most consequential prior art for claim 1 of '104, because they appear to be directed to the same problem space. I could not retrieve or verify these within the available steps, so I flag them as a recommended next research target rather than asserting a § 102 conclusion. If the earlier-generated summary is treated as authoritative on the citation count (8), these "Similar Documents" are not part of the front-page citation set — which is itself worth noting, since it may mean the examiner did not cite them.

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Cross-reference consistency check

• The earlier summary correctly noted the claim 10 "polarity" vs. specification "polarization" discrepancy. That matters here: if claim 10 is read literally as polarity (a signal-sign characteristic), then US 3,488,586 and US 3,794,841 (both of which drive/switch a light signal between states) become more relevant to claim 10 than if it were read as polarization (an optical polarization state). I preserve the literal reading and do not harmonize it.
• No contradiction found between the earlier summary and the citation table in the authoritative patent text; the eight-reference list matches exactly.

Uncertainty statement

My tooling is general web search, not authenticated USPTO/PatentCenter or PTAB access, and I was cut off before verifying US 4,589,404, US 4,870,952, and US 4,878,045 in full text. The § 102 assessments above are based on verified full-text where available and on title/bibliographic data (explicitly flagged) where not. Nothing here should be treated as a legal conclusion of anticipation or obviousness.

I'll ground this obviousness analysis by pulling details on the face-cited prior-art references before combining them.

Excellent detail on the face-cited references. Let me characterize the remaining medical/data-link references and check the "Similar Documents" that bear directly on the randomness limitation.

Obviousness Analysis — US 5,680,104 ("Fiber Optic Security System") under 35 U.S.C. § 103

Note on method and scope. This analysis builds on the two previously prepared sections (Patent Summary, Litigation Summary) and does not repeat them. Per the task instruction, I use the prior-art references listed on the US5680104 Google Patents page — specifically the eight references appearing in the "Patent Citations (8)" section, which are the references of record on the face of the patent. Where a limitation is not reached by those eight, I flag it explicitly and, in one clearly labeled supplement, note that the page's "Similar Documents" list contains a reference directly on point for the pivotal "random signal" limitation. I do not auto-correct any identifier; I preserve the claim term "polarity" (claim 10) versus the specification's "polarization," as previously flagged.

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A. Legal framework and assumptions

Effective date / prior-art status. The application was filed 1996‑05‑31 (no earlier priority asserted). Every one of the eight face-cited references issued between 1970 and 1989 — all more than one year before the filing date — so each is prior art under §102(b). All are therefore available for §103 combination.

Governing test. Graham v. John Deere (scope/content of the prior art; differences; level of ordinary skill; secondary considerations), as elaborated by KSR Int'l v. Teleflex (a combination is obvious where the elements were "known," the combination is "a predictable use of prior-art elements according to their established functions," or the improvement is a "design choice"/"obvious to try" with a reasonable expectation of success).

Claim construction hook. Independent claim 1 is drafted in classic means‑plus‑function form ("means for generating," "means for comparing," "means for monitoring"). Under §112(f) these terms are construed to cover the corresponding structures disclosed in the specification and equivalents. This materially widens the scope of the prior-art mapping (e.g., Honda's "fiber-cutting detecting circuit" and its AND logic can fairly be read as an equivalent "means for comparing" and "means for monitoring").

Level of ordinary skill (POSITA). A person of ordinary skill at the 1996 priority date would be an engineer with a bachelor's degree in electrical/optical engineering (or equivalent) and a few years' experience in optical signal transmission, opto-electronic detection, or security/alarm electronics — comfortable with LED/photodiode drive circuits, RC filtering, comparators/thresholds, synchronous (lock‑in) detection, and closed-loop level control. I assume this level throughout; it is a reasonable, defensible definition and the one most favorable to a validity challenge.

Source limitation (stated up front). I retrieved full text for US3488586, US3794841, US4812641, US4878045 and US3742947. I could not retrieve the substantive full text of US3986498 ("Remote ECG monitoring system"), US4589404 ("Laser endoscope") or US4870952 ("Fiber optic illuminator for use in surgery") in this session, and I could not retrieve the text of US4577184 (discussed in the supplement). I therefore do not assert what those references disclose beyond their titles and the classification/citation data on the page. This is an analytical opinion, not a legal freedom-to-operate or invalidity opinion.

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B. The eight references at a glance

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C. The invention versus the art — element-by-element for claim 1

Claim 1 (apparatus) has six functional blocks. Mapping against the face-cited art:

Reading. The only element of claim 1 that no single one of the eight references supplies in full is the closed-loop "compare-and-adjust-the-emitter" block (element e), and — depending on how strictly "simultaneously triggering said detector" is read — the synchronous-trigger limb of element (d). Both of these are supplied by the secondary references. Element (f) is plainly present in Honda, reinforced by '4812641.

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D. The primary reference: US4878045 (Honda)

Honda is the natural §103 anchor and is substantially anticipatory in structure:

• An optical fiber runs through a locking cable; a light-emission diode (1) is at one end and a phototransistor (4) at the other — elements (a)–(c).
• A generator circuit 5a (pulse generator) produces pulse signal Pa, which drives the LED to emit photo pulse signal Ph — the emitter-trigger limb of element (d), with the pulse itself carrying a recognizable (identifiable) characteristic.
• A receiver circuit 5b reproduces Pc from the received light, and a fiber-cutting detecting circuit 5c is supplied with both Pa and Pc and "determine[s] fulfillment of an AND condition between the levels of the signals Pa and Pc," generating an abnormality signal Pd when the AND is not met → warning device 6 (buzzer) — element (f), and a functional analogue of the in-phase/synchronous comparison that gives claim 1 its character.
• The security use is identical in kind to the '104 patent: a fiber linking two objects, with alarm on tampering with the fiber.

What Honda does not teach: (i) any feedback that adjusts the emitter to conform a later pulse to a reference (Honda is open-loop); and (ii) any random drive — Honda's generator is expressly a pulse generator "having a predetermined constant pulse repetition period," i.e., the opposite of random.

That gap (ii) is the crux of the whole validity question, and I return to it in §F.

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E. The combinations

Combination 1 (primary): Honda '045 + Cosentino '841 — meets claim 1

What Cosentino contributes. Cosentino's modulator is literally a comparator-that-drives-the-emitter-with-feedback: op‑amp comparator 13 drives LED 33 through a push‑pull stage, and the emitted switching signal is tapped back (lead 27) into the comparator through an integrator 14 (R28/C29) and an RC low-pass filter 15 (R31/C32). The loop even internally generates a reference signal e_i(t) (a 3 kHz sinusoid) against which the drive is regulated, and the received signal is recovered by a demodulator 12 using limiter 35 + integrator 36 + RC low-pass filter 37 — i.e., RC-time-constant averaging of the received light.

Mapping. Cosentino supplies claim 1 element (e) ("means for comparing said pulse received by said detector with a predetermined reference to provide an output for adjusting said emitter to conform a subsequent said pulse to said reference") and the averager/ RC structure that the '104 specification relies on. Combined with Honda's (a)–(d) and (f), the two together read on claim 1.

Motivation to combine (KSR). Both are optical links using an LED emitter and a photodetector separated by a light path. Honda itself is built around detecting loss of transmitted light, and Honda's stated goal is reliable detection of fiber compromise — which presupposes a stable, known nominal optical power. A POSITA seeking to keep that nominal power stable against exactly the perturbations the art already worried about — LED aging, temperature, connector dirt and misalignment (named in '586), and the axial-movement/bending stresses Honda itself discusses in its locking cable — would naturally adopt a known closed-loop emitter level-control technique such as Cosentino's. The result (stabilized launched power → more reliable threshold comparison) is predictable, and the combination is "the familiar arrangement of known elements according to known methods." Independent of '104's anti-spoofing purpose, the engineering motivation is strong.

Combination 2: Honda '045 + GE '4812641 — meets claim 1's comparison/threshold blocks

GE '4812641 discloses two detectors — one sensing injected optical power, one sensing output power — and a comparator whose output varies with the difference, using a set threshold to declare a failure. This is a clean teaching of comparing a received signal against a predetermined reference (the transmitted level) and of a threshold-based monitor, reinforcing claim 1 elements (e)-functional and (f), and providing a second-detector architecture that a POSITA could use to implement Honda's comparison more robustly. Motivation: '4812641 addresses the same problem as Honda — detect a break/leak in the fiber — using input/output power comparison; combining it with Honda's security cable is a combination of references addressing the same fiber-integrity problem, with predictable results.

Combination 3: Honda '045 + GE '586 — supplies the modulation-characteristic and the why

GE '586 is an LED/pulse light link and, critically, expressly frames the problem the '104 feedback loop solves: the analog LED approach suffers "calibration dependence … upon the light generation and transmission efficiency," and "any dirt, mis-alignment of the optical path, etc., could greatly affect the system calibration." A POSITA reading '586 is directly motivated to add compensation to an LED link. '586 also supplies identifiable characteristics (pulse, frequency) for the "identifiable characteristic" recitation.

Recommended 4-way combination

Honda '045 (primary) + Cosentino '841 (feedback/averaging) + GE '4812641 (threshold comparison) [+ GE '586 for the LED/frequency/motivation]. This reads on claim 1 and on most of the dependents (see §G). None of the four is remote in field from the others: all are electrical-optical signal-transmission/detection systems, and the two "security" uses (Honda, '4812641) share the exact problem of detecting a compromised fiber.

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F. The pivotal limitation: the "random signal" of claim 18

Claim 1 recites only "means for generating a signal"; the word random does not appear in apparatus claim 1. It appears in the specification and, decisively, in independent method claim 18 ("generating a random signal"; "simultaneously triggering an emitter and a detector with said random signal").

This is the strongest non-obviousness argument in the patent. Of the eight face-cited references:

• Honda expressly uses a generator of constant, predetermined pulse repetition period — the antithesis of random. A POSITA starting from Honda is affirmatively steered toward a fixed, predictable drive.
• None of '586, '841, '947, '4812641 (nor the three I could not retrieve) is described on this page as teaching random or noise-like modulation of a transmitted probe.

So, on the eight face-cited references alone, method claim 18 is not readily obvious, because the "random signal" element is neither disclosed nor suggested, and Honda arguably teaches away from it.

Supplement (clearly outside the eight): the same Google Patents page, in its "Similar Documents" list, includes US4577184A, "Security system with randomly modulated probe signal" (1986‑03‑18) — which, on its title and date, would supply precisely the missing "randomly modulated probe signal" element and would make claim 18 a straightforward combination (random probe-signal security system + Honda's fiber/LED/photodetector/alarm architecture + Cosentino's feedback). I was unable to retrieve US4577184's text in this session and therefore do not assert its disclosure; I flag it as the single most important lead. Other items on that "Similar Documents" list — US5055827 and US4292628 ("Fiber optic security system"), US5003292, US5198799 ("Opto-electronic security fence") — are likewise fiber-optic security systems in the same field and would strengthen the "field of endeavor" and "reasonable expectation of success" showings, but are not among the face-cited eight either.

Bottom line on randomness. A §103 challenge that relies only on the eight cited references should be expected to fail as to the "random signal" limitation of claim 18; a challenge that adds a random/pseudo-random-modulation reference (e.g., on the page, US4577184) would very likely succeed. The motivation for adding randomization — making the transmitted probe signal un-duplicable so a "pseudo link" cannot spoof the system — is a known anti-spoofing purpose, and (importantly) it is the ordinary creativity of a POSITA rather than the applicant's own disclosure that supplies it, since defeating spoofing via an unpredictable signal is a generic security expedient.

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G. Dependent claims

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H. Counterarguments a patent owner would raise (and how they fare)

1. Teaching away on randomness (claim 18). Strong. Honda's constant-repetition-period generator points away from randomness. This is the patent's best defense and is why claim 18 likely survives the eight cited references alone.
2. Non-analogous art. A patent owner would argue the core secondary references are medical/data-link devices (optically isolated ECG, endoscope, surgical illuminator, FM telemetry) and laser-machining monitors — not "security." This has force for the medical references ('947, '586 arguably, '490/'952). It has little force for Honda (expressly a vehicle antitheft security system) and '4812641 (fiber-integrity failure detection — same problem of detecting a compromised light path). So the Honda + Cosentino + '4812641 combination is largely insulated from the analogous-art attack, because Honda and '4812641 are themselves in the tamper/failure-detection field, and Cosentino is a generic optical-link component supplier. Field-of-endeavor ("optical signal transmission and detection") and "reasonably pertinent to the problem" (stabilizing and comparing an optical link's signal) both cut in favor of combination.
3. Synergy / unpredictable results. Weak. The combination yields the expected result: a stabilized, compared optical signal with a threshold alarm. Nothing in the claims reflects a result beyond the sum of the parts.
4. Secondary considerations. None located. The Litigation Summary section found no litigation, and the patent lapsed in 2001 (fee-related) after a ~4-year enforcement window — there is no evidence in the record reached here of commercial success, licensing, copying, or industry praise attributable to the claims. Absent such evidence, there is no objective indicia to rebut an otherwise strong prima facie case.
5. The '104 loop is complex/expensive (per US7135970's later criticism). Not a §103 factor, but it is consistent with the "obvious-to-implement-with-known-components" theme.

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I. Bottom line

• Claim 1 (and dependents 2, 3, 5–9, 12, 15, 16, 19–21) would very likely be obvious over the combination US4878045 (Honda) + US3794841 (Cosentino) + US4812641 (GE), with US3488586 (GE) supplying the LED/modulation-characteristic teachings and the explicit dirt/misalignment-drift motivation. Honda supplies the fiber/LED/photodetector/generator/compare-and-alarm architecture; Cosentino supplies the closed-loop "adjust the emitter to conform to a reference" comparator with RC averaging; '4812641 supplies the predetermined-reference threshold comparison; '586 supplies the LED/pulse/frequency and the motivation. KSR alignment is strong (known elements, known functions, predictable result, explicit engineering incentive).
• Claim 18's "random signal" is the load-bearing limitation and is not made out by the eight face-cited references; Honda in fact teaches the opposite (constant period). Claim 18 should be treated as non-obvious over the cited eight. It would likely become obvious only with a random/pseudo-random-modulation reference — the page's own "Similar Documents" list contains US4577184 ("Security system with randomly modulated probe signal"), which is the most promising such reference (unverified here).
• Claims 4 (high/low window), 11 (injecting optical noise into the fiber), 13–14 (adaptive time-response that alarms on fast/large changes), and 17 (added shot noise) are the weakest for a challenger using only the cited art; each is either not disclosed by the eight or supported only by generic "design choice" reasoning, so these claims would likely be the last to fall.
• Cross-reference check: nothing in this analysis contradicts the previously generated Patent Summary or Litigation Summary. The "polarity" (claim 10) vs. "polarization" (specification) discrepancy flagged earlier remains; under §103 it is a minor point, but it is preserved here as a §112 issue rather than harmonized.

Caveat, restated: I could not retrieve full text for US3986498, US4589404, US4870952, or US4577184 in this session; my mappings for those are limited accordingly, and the conclusions above are analytical predictions under §103, not a legal opinion.