US 6485124

I'll search for authoritative information on this patent, including litigation and docket records.

Let me search for the specific litigation docket and any 2026 Federal Circuit activity.

US Patent 6,485,124 — Summary

All identifiers below are taken literally from the authoritative full-text record you supplied; nothing has been auto-corrected.

Assignment chain (from the record): Lexmark International, Inc. (assignments recorded 2001-07-02 and re-recorded 2002-01-04 to correct the second assignor's name) → Fuani Electric Co., Ltd. / FUNAI ELECTRIC CO., LTD (recorded 2013-05-14, effective 2013-04-01) → Slingshot Printing LLC (recorded 2019-03-29, effective 2019-03-29).

Note the literal spelling discrepancy in the record: the initial assignment names "KROGER, PATRICK LAWRENCE," and the 2002 re-record corrects the second assignor's name to "KROGER, PATRICK LAURENCE."

Abstract (as issued)

"An alignment detector that detects an alignment of a printhead of a printer, with the alignment detector including a photodetector and a single focusing element focusing a point on a media to a point on the photodetector. The alignment detector can be used to detect the alignment of the printer by scanning the alignment detector across the media and detecting predetermined marks previously printed on the media by imaging the predetermined marks using the alignment detector. The area between the single focusing element and the photodetector may be filled by a translucent material, such that there is no air gap between the two."

Independent claims in plain language

Claim 1 — Printing apparatus. A printer with three things: (a) a light source; (b) an alignment sensor made of a detector plus a single focusing element that images a point on the media onto a point on the detector; and (c) a control unit that decides, from the sensor's detection of a pre-printed mark, whether the printer is aligned. The novelty hook is the "single" focusing element performing true point-to-point imaging, versus prior designs that needed a second lens to achieve point detection.

Claim 9 — Method of detecting mis-alignment. Three steps: (a) scan a media for a predetermined mark; (b) detect that mark by imaging a point on the media onto a point of a detector using a single focusing element; and (c) decide whether the apparatus is mis-aligned based on whether the detected mark sits in its expected position on the media.

Claim 13 — Alignment detector. An apparatus-level claim to a single focusing element made of a translucent material that focuses an image of a point on the media onto a point on a detector, where the region between detector and focusing element is filled with that translucent material (i.e., no air gap, so no refraction compensation is needed). This is the "single-unit, mass-producible, low-cost" embodiment described in the spec.

The dependent claims add: translucent material filling the gap (claim 2, clear polymer per claim 3, focusing element made of that material per claim 4); housing positioned one focal length from the media (claim 5); apertured photodetector, optionally shaped to match the mark (claims 6–7, 11, 14); a housing arrangement with no aperture blocking light to the focusing element (claims 8, 16); and imaging through the translucent material without pre-blocking reflected light (claims 10, 12).

Minor drafting note: claim 4 uses "where" in place of "wherein" in the printed text.

Litigation and CAFC records

District court. Google Patents links the US 6,485,124 family to Texas Western District Court case 6:19-cv-00364. That docket is Slingshot Printing LLC v. HP Inc., filed 2019-06-11, assigned to Judge Alan D. Albright, nature of suit 830 (Patent), cause 35 U.S.C. § 271. Sources: UniCourt case page; related Slingshot/HP dockets 6:19-cv-00362, 6:19-cv-00363, and later 6:19-cv-00549, 6:20-cv-00048 (Docket Alarm).

Caveat / uncertainty: I could not independently confirm from a complaint text that US 6,485,124 itself was one of the asserted patents in 6:19-cv-00364. The complaint excerpts I retrieved for the related Slingshot/HP actions list other patents (e.g., 7,484,823 and 7,559,629). The 6:19-cv-00364 complaint was not available in my search results, so the family-to-case association comes from the Google Patents litigation link and should be treated as unverified.

CAFC 2026 dockets. I found no 2026 Federal Circuit appeal specifically identifying US 6,485,124. The 2026 Federal Circuit activity involving the current assignee is a cluster of Slingshot Printing LLC v. Canon U.S.A., Inc. appeals from PTAB IPRs on other Slingshot patents:

• 24-2132 — Rule 36 judgment affirming IPR2022-01416, entered May 7, 2026 (CAFC PDF)
• 2025-1032, 2025-1033, 2025-1034, 24-2127, 24-1956 — additional Slingshot/Canon appeals; oral argument audio posted July 6, 2026 (CAFC)
• Press coverage confirms these were 2026 wins for Canon on inkjet printhead patents (Morgan Lewis, Law360, July 21, 2026)

None of those records ties to 6,485,124, so I am reporting a negative result rather than an inference.

Two flags worth stating plainly

1. Date conflict. Your message states the current date is April 26, 2026, but several retrieved records are dated after that (CAFC Rule 36 judgment of May 7, 2026; oral argument audio dated July 6, 2026; a Law360 note dated July 21, 2026). I am reporting what the sources show rather than reconciling the discrepancy.

2. Expiry matters for any litigation analysis. The record shows "Expired – Lifetime" with anticipated expiration 2021-07-02. US 6,485,124 is therefore not in force as of any 2026 date, which is consistent with it not appearing in the 2026 CAFC activity above. Any residual remedy would be limited to past damages within the applicable limitations period — I make no legal conclusion on that point.

Bottom line: Everything about the patent itself (title, inventors, assignee chain, dates, abstract, claims) is authoritative from the full text you supplied. The district-court linkage is plausible but unverified at the complaint level, and the 2026 CAFC search returned no docket naming this patent.

I'll research litigation involving US patent 6485124 using multiple sources.

I'll verify the structured-data default against public sources before reporting.

Let me check a few more angles — the litigation docket and any IPR filings by known challengers.

Let me run a few final targeted checks before concluding the absence is real.

Proceedings overview

There are zero AIA trial proceedings on file against US 6,485,124.

The structured "PTAB proceedings on file" block (USPTO Open Data Portal, canonical source) returns no IPR, PGR, or CBM for this patent, and my independent web checks surfaced none either. The count by status is therefore: active 0 / claims invalidated 0 / claims sustained 0 / settled 0 / institution denied 0. The bottom line for a defendant is unusual and, on this record, not the familiar "hardened patent" story: US 6,485,124 has never been tested at the PTAB — but it also expired on 2021-07-02, so the real defensive posture is not "survive the IPR" but "the enforceable damages window has closed."

Because the structured data is the canonical list and it is empty, I have not invented a proceeding. Below I explain what is and is not on file, and what adjacent, verifiable activity exists in the same patent family's litigation campaign.

No proceedings to itemize

No ### {PROCEEDING_NUMBER} — {Petitioner} v. {Patent Owner} entries exist for US 6,485,124. I will not manufacture one. What follows is the verified surrounding context.

Adjacent activity that is not a proceeding on this patent

These are real, sourced, and frequently confused with proceedings on the patent-in-suit — flagging so a defendant's diligence memo doesn't conflate them:

• Slingshot Printing LLC v. HP Inc., No. 6:19-cv-00364 (W.D. Tex.) — filed 2019-06-11 before Judge Alan D. Albright; US 6,485,124 was among the sixteen Lexmark-origin patents asserted in the three complaints filed that day (The Recycler; docket summary; Unified Patents litigation record). An amended complaint followed on 2019-09-20. HP responded with IPRs against other patents in the portfolio — e.g., IPR2020-01086 challenged claims 1–5 of U.S. 7,014,299 (petition) — but I found no corresponding petition on 6,485,124.
• Canon IPRs against Slingshot (2022–2023) — IPR2022-01414, -01416, IPR2023-00309, IPR2023-00312, etc., all directed to different Slingshot patents (U.S. 7,195,341; 7,152,951; 7,290,864; 7,484,823). The Board invalidated claims and the Federal Circuit affirmed on appeal (e.g., Slingshot Printing LLC v. Canon U.S.A. Inc., No. 24-2127 (Fed. Cir.), panel of Prost, Schall, Stoll). None of these challenged 6,485,124.

Do not rely on those decisions as estoppel or as claim-cancellation on this patent. They bind different claims of different patents.

Strategic summary

Claim status on 6,485,124: all 16 claims are UNTESTED at the PTAB, and all 16 are expired. No claim has been canceled, and no claim has been sustained in an AIA trial. The patent's legal status per the ODP record is "Expired - Lifetime," with anticipated expiration on 2021-07-02 (20 years from the 2001-07-02 priority/filing date). Claims 1–16 therefore stand as issued — but with a terminal date five years in the past as of today (2026-09-30). That combination is rare: an untested patent is usually a risk (no PTAB record to attack or lean on), but an expired patent is a fundamentally different asset. There is no injunction available, no ongoing royalty, and damages are limited to past infringement within the 35 U.S.C. § 286 six-year lookback — which, measured from today, no longer reaches the post-expiration period at all.

Estoppel landscape: there is none. Section 315(e)(2) estoppel attaches only to a petitioner that obtained a final written decision. Since no IPR/PGR/CBM reached an FWD on this patent, no party — HP, Canon, or anyone else — is estopped from raising any § 102/§ 103/§ 112 ground against 6,485,124. For a defendant being asserted against today, every prior-art ground is still on the table, including art that was cited during prosecution (the 23 references of record, e.g., Beauchamp U.S. 5,448,269 and 5,975,674, Hubbard U.S. 4,907,013, Lindenfelser U.S. 5,534,895, Matsuda U.S. 6,084,607, and the HP optical-sensor family around U.S. 5,905,512 / 6,172,690 / 6,134,750). That cuts both ways: no estoppel against you, but also no roadmap of what the Board has already blessed.

Pattern signals. The owner of record is Slingshot Printing LLC (acquired from FUNAI ELECTRIC CO., LTD. on 2019-03-29), a non-practicing entity that ran the Lexmark/Funai inkjet portfolio as a monetization campaign — asserting against HP in 2019 and Canon in 2022. Slingshot litigated PTAB appeals aggressively in the Canon matters (multiple notices of appeal in 2024; a string of Federal Circuit losses in 2026). Notably, no defensive aggregator appears in the chain for this patent — the Unified Patents link in the ODP record is a litigation-data pointer to the HP case, not evidence of a Unified-filed IPR. The single most telling signal: Slingshot asserted 6,485,124 in 2019 but never saw it IPR'd, and the patent then expired in 2021. In a portfolio campaign, the patents that don't attract IPRs are often the ones the defendant chose to fight with § 101/§ 112 or invalidity in district court — or the ones whose damages exposure didn't justify the filing fee.

Recommended next steps

1. If you are a defendant being asserted against today, lead with expiration, not validity. The patent expired 2021-07-02 (Google Patents legal status). Any demand letter asserting ongoing infringement of 6,485,124 is facially wrong. A § 286 six-year damages lookback from 2026-09-30 reaches back to 2020-09-30 — but the patent's own term ended 2021-07-02, so the recoverable window (if any device even infringes) is roughly nine months, not six years. Quantify that before responding.

2. There is no FWD to quote, and I want to be explicit about that. The instructions ask that, "if the patent has claims invalidated, link explicitly to the FWD and quote the disposition." I cannot, because no FWD exists. I will not paraphrase or approximate one. If a counterparty or an old opinion asserts that "claims 1–5 of 6,485,124 were canceled," that assertion is false — the invalidations in this family belong to U.S. 7,014,299, 7,290,864, 7,484,823, and 7,152,951.

3. Verify directly against the authoritative registries. My web checks were bounded and I hit a tool-call limit before exhausting them. Before finalizing any opinion letter, confirm the null result against:

• PTAB E2E / PTAB Center (search by patent number 6485124), and
• USPTO Patent Center for the application's post-grant record.
  Live checks at filing time, not my search summary, should be the record cited.

4. Preserve the invalidity record while it's cheap. Even though the patent is expired and the Board never weighed in, the file history and the 23 prosecution citations remain usable in a § 282 district-court invalidity defense for any surviving damages window. Because no estoppel binds you, an expired-patent defendant retains the full § 112 written-description/enablement toolkit against the "single focusing element" and "translucent material fills an area" limitations of claims 1, 13, and 14 — none of which the Board has construed.

Caveat on completeness: I found no PTAB activity, and the structured ODP block likewise reports none as of the most recent ingest. The absence of AIA trials is itself a signal here — but the stronger signal for a defendant on US 6,485,124 is the 2021-07-02 expiration, which moots most of what a PTAB proceeding would have accomplished.

I'll verify the assignment chain and litigation context before reconstructing the record.

Let me try to retrieve the recorded correspondent of record for each reel/frame entry.

US 6,485,124 — Assignment & Ownership Reconstruction

Patent: US 6,485,124 B1, "Optical alignment method and detector" — filed 2001‑07‑02, granted 2002‑11‑26, expired 2021‑07‑02 (full 20‑year term; maintenance fees paid at 4, 8 and 12 years).
App. no.: 09/897,496 · Pre‑grant pub.: US 2003/0001917 A1

Sourcing caveat, stated up front. Every reel/frame, date and party below is drawn from the USPTO assignment records as mirrored in the Google Patents legal‑events block for this patent (the same underlying Assignment Center records). I was not able to retrieve the recorded correspondent field — Google's mirror does not expose it, and my attempts to pull the underlying reel/frame abstracts returned no results. I have therefore marked correspondent data as unavailable rather than guessing. Verify at the USPTO Assignment Center (search 6485124) or assignment.uspto.gov.

Inventors

Pattern notes: The only anomaly is the spelling correction of the second inventor's name — an administrative fix, not an ownership event. There is no evidence in the assignment record of either inventor departing Lexmark within 12 months of filing, and no evidence of inventor‑originated transfers. (Absence of evidence here is genuine absence — the assignment record does not track employment.) No pre‑issuance fire‑sale or inventor‑retained interest is discernible; both inventors assigned to Lexmark on the day of filing.

Original assignee

Lexmark International, Inc. (Kentucky), named as assignee on the face of the issued patent and on reel 011994/0989.

• Products: Yes, the claims were embodied. Lexmark was, at filing (2001), a full‑line inkjet and laser printer OEM, and the specification itself describes the alignment detector operating inside a printing apparatus with a transport unit, printheads, a 640 nm red LED source and a controller running the alignment routines of FIGS. 2A–2C. This is a production printer‑component patent, not a paper asset at origination.
• Primary line of business: Inkjet and laser printers, MFPs, and consumables; publicly traded (NYSE: LXK) following its 1991 spin‑off from IBM.
• Current status: Operating, but no longer in inkjet. Lexmark announced its exit from inkjet hardware in 2012 and, per the litigation record below and trade reporting, sold its inkjet technology IP and related assets — including this patent family — to Funai Electric Co., Ltd. for approximately US$100 million in 2013. Lexmark was taken private in 2016 by a consortium that included Ninestar/PAG Asia. Note: my understanding that Xerox later acquired Lexmark comes from background knowledge, not from the sources retrieved in this session — treat that one point as unverified here. Lexmark has never filed a bankruptcy proceeding relevant to this patent.

Assignment timeline

Four recorded events. The second is a correction, not a transfer; the third and fourth are the substantive conveyances.

• 2001‑07‑02 (executed) / recorded 2001‑07‑02 — Reel 011994/0989

  • Conveyance: Assignment
  • Assignor: King, Dave Golman; Kroger, Patrick Lawrence
  • Assignee: Lexmark International, Inc., Kentucky
  • Correspondent: Not retrievable from the sources used — see caveat above. Flag as an open verification item.
  • Context: Initial assignment of inventors' rights to their employer (acquisition by the operating company).

• 2001‑07‑02 (effective) / recorded 2002‑01‑04 — Reel 012438/0079

  • Conveyance: Assignment (re‑record to correct the second assignor's name)
  • Assignor: King, Dave Golman; Kroger, Patrick Laurence
  • Assignee: Lexmark International, Inc., Kentucky
  • Correspondent: Not retrievable.
  • Context: Internal/administrative correction of the prior recording; no change in ownership. Importantly, this is not a cascading transfer — the assignee is identical.

• 2013‑04‑01 (effective) / recorded 2013‑05‑14 — Reel 030416/0001

  • Conveyance: Assignment
  • Assignor: Lexmark International, Inc.; Lexmark International Technology, S.A. (Lexmark affiliate — portfolio consolidated before sale)
  • Assignee: Funai Electric Co., Ltd., Japan
  • Correspondent: Not retrievable.
  • Context: Strategic portfolio sale — part of Lexmark's ~US$100M divestiture of its inkjet technology and assets to Funai. Not a bankruptcy fire‑sale; this was an announced exit from a product line by a solvent public company.
  • Recorded in the W.D. Tex. / E.D.N.Y. complaints as: "Funai acquired Lexmark's inkjet printing technology intellectual property and related assets, including the Patents in Suit."

• 2019‑03‑29 (executed) / recorded 2019‑03‑29 — Reel 048745/0551

  • Conveyance: Assignment ("all rights, title and interest")
  • Assignor: Funai Electric Co., Ltd.
  • Assignee: Slingshot Printing LLC, Maryland
  • Correspondent: Not retrievable. This is the single most important field to recover — see signal 3 below.
  • Context: Transfer to an assertion vehicle. Slingshot's own complaint states it "is in the business of licensing patented technology." The recording lands 74 days before Slingshot's first infringement suit naming this family (W.D. Tex., filed 2019‑06‑11). Note also that in the HP litigation the court ordered Slingshot to produce "any agreements between Slingshot Printing LLC (and any affiliates) and Funai Electric Co., Ltd. (and any affiliates)" (text order granting motion to produce, 1:20‑cv‑00184, W.D. Tex.) — i.e., the court itself treated the Funai–Slingshot relationship as something needing disclosure.

No defensive‑aggregator link appears anywhere in this chain, and no post‑2019 assignment is recorded. Slingshot Printing LLC remains the current assignee per Google Patents.

Timeline diagram

timeline
    title Ownership of US 6485124
    2001 : Filed and assigned to Lexmark
         : Reel 011994 frame 0989
    2002 : Name correction re-record
         : Reel 012438 frame 0079
    2013 : Lexmark sells inkjet portfolio to Funai
         : Reel 030416 frame 0001
    2019 : Funai assigns to Slingshot Printing LLC
         : Reel 048745 frame 0551
         : Slingshot sues HP in W D Texas

NPE / troll‑pattern signals

1. Shell‑entity transfer — PRESENT.
The patent moved from an operating OEM (Funai — a Japanese consumer‑electronics manufacturer that produced inkjet printers and cartridges, including under the Kodak brand) to a licensing‑only limited liability company at reel 048745/0551 (2019‑03‑29). Concrete, non‑naming evidence: (a) Slingshot's own pleading admits it "is in the business of licensing patented technology" and pleads only ownership, never manufacture; (b) it is a Delaware LLC; (c) its pleaded address differs across its own complaints — 8455 Colesville Road, Suite 830, Silver Spring, MD 20910 in one HP complaint and 10015 Old Columbia Road, Suite B215, Columbia, MD 21046 in the Canon complaint — the classic lightweight‑presence footprint of a shell. Name‑suffix alone would not carry this; the licensing‑only admission does.

2. Known asserter in the chain — PRESENT.
The current assignee is not on the enumerated classic list (Acacia, Marathon, IV, Wi‑LAN, Mosaid/Conversant, Pendrell, Vringo, Innovatio, MPHJ, Lumen View, Round Rock, Erich Spangenberg entities). However, the signal's own catch‑all applies: Unified Patents tags plaintiff "Slingshot Printing LLC" with entity type "NPE (Patent Assertion Entity)" in its litigation database (Unified Patents case list). The assertion record is extensive: six‑plus W.D. Tex. suits against HP filed 2019‑06‑11 (including the family litigation flagged on Google Patents for this patent, Slingshot Printing LLC v. HP Inc., 6:19‑cv‑00364), the 2022 E.D.N.Y. campaign against Canon (2:22‑cv‑00123 and 2:22‑cv‑01852), at least eight Canon IPRs (IPR2022‑01414 through IPR2023‑00313), and Fed. Cir. appeals Nos. 2024‑2132 and 25‑1033, in which the PTAB's invalidity holdings were affirmed (Rule 36 judgment, 2026‑05‑07; opinion, 2026‑07‑16). Slingshot's PTAB mandatory notices name Slingshot itself as the sole real party‑in‑interest.

3. Repeat correspondent across the chain — NOT VERIFIABLE (open item).
I could not retrieve the recorded correspondent for any of the four reel/frame entries, so I cannot make this call and will not infer it. What I can report as a proxy — and it is only a proxy, since litigation counsel ≠ recording correspondent — is that the assertion‑side counsel recurs heavily across Slingshot's matters: Daignault / Iyer / Juang / Siem (Daignault Iyer LLP) and local counsel Raymond W. Mort, III on the 2019 HP suits; Goldberg Segalla LLP (Charkow, Iyer, Juang) plus Lerner David on the HP IPRs; and Fitch, Even, Tabin & Flannery LLP (Maloney, Henkelmann, Borsos) and MoloLamken in the Canon matters and appeals. Action item: pull the correspondent field for reels 011994/0989, 012438/0079, 030416/0001 and especially 048745/0551 from Assignment Center and compare.

4. Cascading transfers — NOT PRESENT.
There is no run of chained LLC transfers inside 24 months. The two substantive transfers are six years apart (2013‑04‑01 and 2019‑03‑29), and the 2001/2002 entries are an assignment plus its own corrective re‑record with an unchanged assignee. This is a two‑hop chain, not a cascade.

5. Pre‑litigation transfer — PRESENT.
Reel 048745/0551 was executed and recorded 2019‑03‑29; the first suit touching this family (Slingshot Printing LLC v. HP Inc., 6:19‑cv‑00364, W.D. Tex.) was filed 2019‑06‑11 — 74 days later, comfortably inside the 6‑month window. The transfer also placed the patent in W.D. Tex. (Judge Alan D. Albright's Waco/Austin docket) for assertion.

6. Bankruptcy fire‑sale — NOT PRESENT.
No Chapter 7 or Chapter 11 appears in the chain. Lexmark's 2013 sale was a voluntary strategic divestiture of a product line (inkjet exit announced 2012); Funai's 2019 transfer was post‑acquisition monetization. Both assignors were solvent.

7. Privateering — UNCLEAR.
The facts fit the outer shape: an operating OEM (Funai, which still built inkjet printers/cartridges) conveyed the portfolio to a licensing‑only LLC that then sued HP and Canon — Funai's direct competitors in inkjet — while Funai itself stayed off the caption. That is suggestive. But the defining element, that Funai directed or benefited from the assertion, is not established on the public record: Slingshot's PTAB mandatory notices list only Slingshot as real party‑in‑interest. The strongest public indicator pointing the other way is that the W.D. Tex. court granted HP's unopposed motion and ordered Slingshot to produce its agreements with Funai and their affiliates — a court‑sanctioned look at exactly this question, which is meaningful but is not itself proof of retained control. Mark unclear pending the production documents or the Assignment Center correspondent field.

8. Defensive aggregator (anti‑NPE) — NOT PRESENT.
The chain terminates at an asserting entity that litigated through 2026, not at RPX, AST, LOT Network, Unified Patents or OIN. The patent has not been neutralized by defensive aggregation. (Its practical assertion value did end independently: the term expired 2021‑07‑02.)

Verdict

NPE — high confidence.

Two strong signals are independently grounded in the record. First, the substantive transfer at reel 048745/0551 (executed and recorded 2019‑03‑29) moved the patent from the operating OEM Funai Electric to Slingshot Printing LLC, a Delaware licensing‑only vehicle that pleads it "is in the business of licensing patented technology" and pleads no manufacturing. Second, that recording landed just 74 days before the first infringement filing touching this family, Slingshot Printing LLC v. HP Inc., 6:19‑cv‑00364 (W.D. Tex., filed 2019‑06‑11), satisfying the pre‑litigation‑transfer signal, with Unified Patents independently tagging Slingshot as an "NPE (Patent Assertion Entity)" plaintiff in its litigation database. The 2019 recording is the last in the chain — no defensive aggregator, no bankruptcy, and no post‑2019 transfer — so Slingshot remains the asserting owner of record.

Not established (do not assume): the recorded correspondent on any entry, and the privateering question of whether Funai directs or shares in the recovery. Both are the obvious next two things to pull.

Verify at: USPTO Assignment Center — patent 6485124 · assignment.uspto.gov patent search · Unified Patents litigation portal · RPX Insight litigation document, Lexmark → Funai → Slingshot chain

I'll verify the patent and its cited references against live sources before building the prior-art analysis.

Let me pull details on the citations most likely to bear on the "single focusing element" and "photodetector" claim limitations.

Let me verify the remaining key references — the light-tube/aperture family (which is directly relevant to claims 8 and 16) and the Xerox reference.

Prior-Art Analysis — US 6,485,124 B1

Note on identifiers: I interpret the number exactly as given. "6485124" = US 6,485,124 B1, "Optical alignment method and detector." I did not normalize or correct it. (The separate document surfaced during searching, US 6,486,124, is a different patent and is not the subject here.)

Source note / limits of this run: I searched Google Patents/Espacenet-USPTO mirrors. The authoritative full text (claims, spec, citation lists) was supplied in the record. I retrieved and verified full or abstract-level text for the most probative references, but I hit my tool-call limit before retrieving full text of all 23 citations — references marked ˢ below are characterized from the patent's own face-of-document citation list plus title/abstract, not from a full-text read. I flag that so you can close the gap.

1. The patent at a glance

The invention's stated point of novelty over the art is narrow and specific: point-to-point imaging performed by a single focusing element (one focusing surface/one focusing operation), replacing the two-lens (or more) point-detection arrangements used previously, optionally potentially embedding the lens and photodetector in a common translucent material so no air gap/refraction compensation is needed, and eliminating the need for a light-blocking aperture/light-tube.

2. Claim-element breakdown (the § 102 yardstick)

Anticipation requires every element in a single reference, arranged as claimed.

• Claim 1 (independent, apparatus): (a) light source; (b) alignment sensor having a detector and a single focusing element that images a point on the media to a point on the detector; (c) control unit determining alignment from detection of a predetermined mark on the media.
• Claims 2–8 (dependent): translucent material filling the lens–detector gap; clear polymer; lens made of that material; housing at a distance equal to the sensor focal length; photodetector having an aperture; aperture shaped to conform to the mark; housing arranged so no aperture blocks light reaching the single focusing element.
• Claim 9 (independent, method): scanning media → detecting a mark by single-focusing-element point imaging → determining misalignment from the mark's position.
• Claims 10–12: translucent-medium imaging; mark-conforming aperture; detection without first blocking a portion of the reflected light reaching the single focusing element.
• Claim 13 (independent, detector unit): single focusing element made of a translucent material, imaging a point on media to a point on a detector, with the gap filled by that translucent material.
• Claims 14–16: mark-conforming aperture; housing supporting source + lens + detector; no aperture blocking light to the focusing element.

The gating limitation for nearly all of these is "single focusing element" performing the media→detector point-to-point image, and the gap-fill translucent material for claims 2–4, 10, 13.

3. Reference-by-reference analysis (the 23 cited references)

All 23 were published before 2001-07-02 and therefore all qualify as pre-AIA § 102(a)/(b) prior art. The column "Claims potentially implicated" states where the disclosure maps onto claim elements; it is not a conclusion of anticipation (see §4).

Tier 1 — Closest to the "sensor images a test mark for alignment" core (claims 1, 9)

Tier 2 — Optical-sensor module / illumination architecture (claims 1, 5, 8)

Tier 3 — Light-tube / aperture references (directly on point for claims 8 and 16, and for claim 6–7 context)

Tier 4 — Detection of misfiring/mispositioned heads and printbar correction (claims 1, 9, 12)

Correction: I have not invented entries. The two entries sometimes mis-transcribed from the list are US 5,259,9xx/5,254,900-family items; the actual listed citation is US 5,250,509 A, below.

| US 5,250,509 A | Hewlett-Packard Co.; filed 1992-05-01; issued 1993-10-19. Automatic maintenance system for drop aperture plate (optics protection). | Drop-aperture-plate protection in an automatic maintenance scheme (optics cleanliness). | Peripheral; claim 1 housing context only. ˢ |
| US 5,427,457 A (as listed: US 5,427,457 / 5,426,457) | Hewlett-Packard Co.; filed 1993-04-30; issued 1995-06-20. Direction-independent encoder reading; position leading and delay, and uncertainty to improve bidirectional printing. | Encoder-based position referencing for bidirectional printing. | Claim 9 context (position reference for mark location). ˢ |
| US 5,297,017 A | Hewlett-Packard Co.; priority 1991-10-31; issued 1994-03-22. Print cartridge alignment in paper axis. | Paper-axis (vertical) cartridge alignment using a carriage sensor. | Claim 1 (vertical/skew alignment counterpart to '124 FIG. 2C). ˢ |
| US 6,152,000-family / US 6,158,344 A | Hewlett-Packard Co.; filed 1998-12-03; issued 2000-12-12. Linefeed calibration using an integrated optical sensor. | Integrated carriage optical sensor used to calibrate media linefeed. | Claim 1 architecture; claim 9 method analogue. ˢ |
| US 6,164,753 A | Hewlett-Packard Co.; filed 1998-02-26; issued 2000-12-26. Optical sensor system to calibrate a printhead servicing location in an inkjet printer. | Carriage optical sensor used to locate servicing station. | Claim 1 architecture context. ˢ |
| US 6,137,503 A | Canon K.K.; priority 1993-05-26; issued 2000-10-24. Ink jet recording apparatus. | Recording-apparatus architecture with optical/detection features. | Claim 1 general-context. ˢ |

Forward citations (NOT prior art — listed for completeness)

Google Patents' "Cited By" set — e.g., US 7,287,771 B2 (HP, optical sensor, 2007), US 7,690,778 B2 (Lexmark, fluorescence-based printhead alignment, 2010), US 9,139,024 B2 (HP, sensor positioning system, 2015), US 7,507,981 B2, US 7,963,475 B2/US 7,783,107 B2 (Seiko Epson) — and the citing-family members JP 2004-317799 A (Canon) and JP 4652929 B2 (Funai) all post-date 2001-07-02 and therefore have no § 102 effect against US 6,485,124.

4. Anticipation assessment under 35 U.S.C. § 102 (honest bottom line)

No single one of the 23 cited references appears to anticipate independent claims 1, 9, or 13 in full. The reason is consistent across the field: the entire cited corpus is the pre-2001 HP/Lexmark/Xerox sensor art that the '124 specification expressly characterizes as using two or more focusing elements (its own FIGS. 1A–1B depict the one-lens and two-lens prior arrangements). The distinguishing limitation — one focusing element performing the media-point→detector-point image — is precisely what the applicant asserts was absent. Concretely:

• Claims 1 and 9: the closest references (US 5,289,208, US 5,250,956, US 5,644,344, US 6,161,914, US 5,448,269, US 5,600,350) disclose the light-source + detector + mark-on-media + control-unit combination, but they detect printed test lines with a quad photodiode, not by point-to-point imaging through a single focusing element. That element is missing, so anticipation fails (though these are the best § 103 bases).
• Claim 13 / claims 2–4, 10: the gap-filling translucent material limitation is the novel core; I found no reference disclosing a lens-and-detector pair embedded in a common translucent medium to eliminate the refractive interface. Not anticipated by any cited reference.
• Claims 8 and 16 (no aperture): the HP light-tube references (US 5,905,512, US 6,172,690) disclose the opposite — an aperture-forming light tube. A reference teaching the presence of an aperture cannot anticipate a claim reciting its absence; these are § 103 context, not § 102 art.
• US 5,430,306 is the sole cited reference teaching a genuinely single optical element concentrating light at a detector, but it is an inkdrop-in-flight detector, not a media-mark alignment imager — so claims 1/9/13 are not anticipated by it.
• Claims 6–7 (photodetector with an aperture shaped to conform to the mark): this is a conventional aperture/mask-on-detector concept; US 5,430,306 (apertures 12/13 defining the probe/beam volume) and the light-tube family are the best § 102/§ 103 candidates for these dependent claims specifically.

Where § 102 might attach at the dependent-claim level: if you are pressing individual dependent claims rather than the independents, the light-tube family (US 5,905,512, US 6,172,690 B1) and US 5,430,306 are the most plausible § 102 hits against claims 6 and possibly 14 (aperture/mask-on-detector), since masked photodetector apertures are squarely conventional there.

Relevance ranking (best → weakest) for a validity challenge:

1. US 5,430,306 — only single-optical-element concentration teaching (claims 1, 6, 13 structurally).
2. US 5,289,208 / US 5,250,956 (and continuations US 5,644,344, US 6,161,914) — complete apparatus/method alignment loop (claims 1, 9).
3. US 5,448,269 / US 5,600,350 — reference-pattern scanning + encoder sampling (claims 1, 9).
4. US 5,975,674 — carriage sensor optical path (claim 1).
5. US 5,905,512 / US 6,172,690 B1 — light tube/aperture (claims 6, 8, 16, by contrast).
6. US 4,907,013, US 5,534,895, US 6,084,607 — the three expressly-named Background references (claims 1, 9).
7. Remainder (HP sensor-module/encoder/service-station art) — architecture context only.

5. Caveats and open items

1. Descriptions for entries marked ˢ depend on the patent's own citation list, titles, and retrieved abstracts; I did not complete full-text reads of every one of the 23 before hitting the tool limit. If you need a formal claim-chart-ready § 102 conclusion, each should be pulled in full (PDF/OCR) and its figures compared element-by-element.
2. Anticipation ≠ relevance. A reference appearing in the "Patent Citations" list of US 6,485,124 does not mean the examiner relied on it for a § 102 rejection; most of these 23 are § 103/background art. Only US 5,600,350 A is flagged as examiner-cited on the face of the document in the record supplied.
3. Date discrepancy noted: the session instruction states the current date as April 26, 2026, while the document-fetch metadata shows 2026-09-30. Either way the patent expired 2021-07-02, which is relevant to any enforcement/litigation value (the W.D. Tex. case 6:19-cv-00364 was filed 2019, i.e., within the term).
4. Pre-AIA § 102(e) may also matter if any candidate is a US patent/publication with an earlier effective filing date; this would require checking each reference's earliest US filing date (e.g., '5644344, '6161914, '5600350 all chain to 1991-10-31 applications).

If you'd like, I can (a) complete full-text § 102 element charts for the seven Tier-1/Tier-2 references, or (b) extend the search to non-cited art filed 1998–2001 that might disclose a molded single-element lens with an index-matched photodetector (the actual novelty), which is where a serious invalidity theory would look next.

I'll research the prior art references cited in US6485124 to ground the obviousness analysis in their actual disclosures.

Let me gather details on additional cited references relevant to the alignment sensing and detector-aperture features.

Obviousness Analysis — US 6,485,124 B1 under 35 U.S.C. § 103

Note on scope and sourcing. Per the task instruction, this analysis is built from the Prior Art section of the US 6,485,124 Google Patents page — i.e., the 21–23 "Citations" and 10–16 "Cited By" entries listed there — supplemented by the located text of those references. I did not have the full claim sets of every reference in hand, so where I rely on a reference's abstract/specification rather than its claims, I say so. Two housekeeping flags:

• The previously generated "Litigation summary" section appears truncated ("I'll research litigation involving US patent 6485124 using multiple sources." with no substance). It is not contradicted by anything below, but it also supplies no assertions to build on. The Google Patents page does record litigation: Texas Western District Court case 6:19-cv-00364 and a Darts‑IP family record (family 25407989). Obviousness is likely relevant there as a validity defense/counterclaim, which is why this analysis matters.
• Identifiers are interpreted literally (e.g., US 6,485,124, US09/897,496; inventor "Kroger, Patrick Laurence" in the re‑recorded assignment vs. "Patrick Lawrence" in the original — not auto‑corrected).

1. The claims at issue and the inventive concept

The independent claims break into three families:

Dependent claims add: translucent fill / clear polymer / lens made of the same material (2–4, 10); housing spaced at the focal length (5, 15); a detector aperture shaped to conform to the mark (6–7, 11, 14); and no aperture blocking light to the focusing element (8, 16).

The specification is candid that the only advance over the admitted prior art is the reduction in the number of optical elements. It expressly characterizes FIG. 1B as prior art in which point 70 is imaged onto phototransistor 100 "using lenses 120 and 110," and states the drawback is that "the alignment sensor of FIG. 1b requires an additional lens 120… the extra focusing elements excessively drive up costs." (Spec., Description of the Related Art). That is a binding admission that (a) point detection with a focusing element on a detector was known, and (b) the second lens existed to perform point detection. Claim 1 therefore differs from the admitted art chiefly by deleting a lens — a fact that frames the entire § 103 inquiry.

2. The relevant prior art in the cited list

All of the strongest references share a field, a problem, and frequently an assignee (Hewlett‑Packard), which matters for the motivation‑to‑combine analysis.

3. Independent claim 1 — obvious

Suggested combination: US 5,856,833 as primary, in view of US 5,289,208 (and/or US 5,262,797).

Every element of claim 1 is disclosed or rendered obvious:

The only arguable difference is the adjective "single." But the specification admits the second lens of the prior art was there precisely to enable point detection. Substituting one lens for two to do the same job is the classic case of a known element performing a known function with predictable results (KSR Int'l v. Teleflex, 550 U.S. 398 (2007)); a "single" lens performing the same imaging is also the anticipated result of mere omission of a component and its function (the omitted relay lens contributed only the same imaging that the remaining lens can be designed to perform). Notably, HP's own sensor in US 5,905,512 / US 6,172,690 already uses one lens (426) to image reflected light onto a photocell.

Claim 1 is obvious.

4. Dependent claims 2–5 — obvious

Combination: US 5,262,797 + US 5,856,833.

• Claim 2 (translucent material filling the lens‑to‑detector area; no air gap). US 5,262,797 expressly discloses that the "lower portion 179 of the chip assembly is transparent (such as clear plastic) to allow reflected light to pass unimpeded to the photodiode" — i.e., a solid transparent medium between the lens 154 and the photodiode 156. US 5,856,833 discloses an epoxy dome 94 encapsulating the LED die. Encapsulating/immersion‑filling optical paths to suppress refraction and simplify assembly is a well‑known packaging technique. Putting these together — a solid clear medium in the lens‑to‑detector gap — yields claim 2 with a predictable result (elimination of an air‑glass interface and the need to compensate for it, which the spec. itself identifies as the benefit).
• Claim 3 (clear polymer). Clear plastic is expressly named in US 5,262,797; polycarbonate is expressly named in US 6,172,690/US 5,905,512. Obvious.
• Claim 4 (lens made of the same translucent material). Once the gap is filled with a clear polymer, molding the lens integrally of the same polymer is an obvious manufacturing choice — US 5,856,833 establishes integral molding of lens structures as known ("Molding these three separate portions as an integrated part assures control of alignment and positioning variables"), and US 5,262,797/6,172,690 use molded polymer optics.
• Claim 5 (housing positioned a distance from the media equal to the focal length). US 5,262,797 explicitly calibrates and drives the carriage "to achieve the optimum focal distances," and reports a fixed lens‑to‑photodiode spacing ("S" = 17.2 mm) and lens‑to‑medium spacing ("So" = 15.1 mm). US 6,172,690 positions lens and photocell "in predetermined positions… relative to print media passing through said apparatus." Placing the sensor one focal length from the media is the definitional requirement of any focus‑based imaging sensor — obvious.

5. Dependent claims 6–8 — obvious (with one caveat)

Claims 6–7 (detector aperture; aperture shaped to conform to the mark).

• US 5,856,833 discloses a detector passage 72 and a detector‑receiving pocket 70 defining the light path to the detector; its lens cluster has a defined radiation‑collecting portion. US 6,172,690/US 5,905,512 go further: the sensor "obtain[s] a more accurate representation of the test pattern mark shape, reflectance value, and position," and the passageway itself is bounded (aperture‑like) so that only normally‑reflected light reaches the photocell.
• A shaped aperture matched to the mark is squarely taught in the HP phase‑plate art from the same alignment‑sensor family cited in this patent's background — e.g., the phase plate in EP 0 622 237 (Cobbs, HP), an opaque plate in optical alignment with the photodetector whose aperture spacing equals the test‑pattern bar spacing (and which may carry both horizontal and vertical apertures). (Caveat: I located this reference via the family/search results, not from the 21‑reference "Citations" list itself; it is supporting rather than primary. Its US counterpart number was not verified in this session. TREAT THE EXACT NUMBER AS UNCONFIRMED.)
• Motivation: if the mark is a vertical row of inkjet nozzles (as the patent's own Fig. 2C/skew discussion contemplates), orienting a slit/aperture to match the mark improves signal‑to‑noise — a predictable design choice.

Claim 8 / claim 16 (no aperture blocking light from reaching the single focusing element). This is a negative limitation describing the absence of a light tube. The prior art HP design (US 5,905,512; US 6,172,690) teaches the opposite — a light tube whose inner wall "diverts light… away from the photocell." That arguably cuts against obviousness for claim 8/16, but it is almost certainly fatal only if the elimination yields an unexpected result. Removing the light tube and instead relying on point‑focusing is a substitution of one known stray‑light‑control mechanism (tubes) for another (converging optics) — predictable per KSR. Claims 8/16 are the strongest non‑obviousness candidates, but the Federal Circuit's "omission of an element and its function" line (In re Karlson) and KSR's "predictable results" rationale both point to obviousness. I would rate claims 8/16 as more likely than not obvious, with the caveat that this is the closest call.

6. Method claims 9–12 — obvious

Combination: US 5,289,208 (and US 5,600,350) + US 5,856,833.

• Claim 9 maps directly onto US 5,289,208: the printer prints test lines, the carriage sensor scans them, and a controller determines mis‑alignment from the imaged mark positions. US 5,856,833 supplies the "single focusing element imaging a point on the media onto a point of the detector" step (lens portion 124). No new apparatus is required.
• Claim 10 (imaging through a translucent material in the gap) — US 5,262,797's clear‑plastic chip portion 179, per § 3.
• Claim 11 (aperture shaped to conform to the mark) — per § 5.
• Claim 12 ("without first blocking a portion of the reflected light… ") — the negative step; US 5,430,306 teaches that a properly designed optical system can be made insensitive to detector/placement imprecision ("positioning of the detector need not be precise in any direction"), implicitly endorsing the convergence approach rather than aperture/tube blocking.

7. Independent claim 13 and dependents 14–16 — obvious

Combination: US 5,262,797 + US 5,905,512 / US 6,172,690 (+ US 5,856,833 for integral molding).

Claim 13 is simply "claim 1's imaging element + claim 2's translucent fill," restated as a standalone detector. US 5,262,797 supplies the transparent clear‑plastic medium between the single lens 154 and the photodiode (portion 179). US 5,905,512 / US 6,172,690 supply a unitary, carriage‑mounted sensor with a single lens and molded polymer body positioning lens, photocell, and LEDs relative to the media — exactly the "made of a translucent material… area… filled with the translucent material" structure. US 5,856,833 supplies integral molding of the lens as the same material as the body. Dependent claims 14 (shaped aperture), 15 (housing with light source), and 16 (no blocking aperture) fall per § 5.

8. Motivation to combine (why a POSA would have done this)

A person having ordinary skill — an inkjet‑printer optical‑sensor designer — would combine these references for several reinforcing reasons:

1. Same field, same problem, same assignee. Every strong reference is a carriage‑mounted optical sensor for detecting ink on media in an inkjet/plotter. Most are HP; the US 6,172,690 family even cross‑references the same HP alignment patents (US 5,170,047; US 5,448,269). Combinability is substantial.
2. The patent's own articulated problem is the motivation. The spec. states the defect of the prior art is cost from "extra focusing elements." Reducing part count/cost while preserving "point detection" is precisely why a POSA would collapse the two‑lens relay into one designed focusing element. KSR holds that "the desire to enhance… a known technique to the same end" supplies the rationale.
3. Predictable substitution of known elements. A single molded lens imaging a point onto a detector (US 5,856,833 lens portion 124; US 5,262,797 lens 154; US 5,905,512 lens 426) is a known element used for its known purpose — the strongest KSR rationale.
4. The "translucent fill" was a known packaging practice in the very same sub‑assemblies (clear plastic 179 in US 5,262,797; epoxy encapsulation in US 5,856,833; polycarbonate molded body in US 6,172,690). Filling the gap to remove refraction is a predictable, low‑risk change.
5. Reasonable expectation of success. In re Etter / In re Longi — a combination that merely arranges known elements with predictable results is obvious. Nothing in the patent asserts a synergy or an unexpected degree (e.g., no claimed resolution or accuracy figure tied to the single‑lens structure).

9. Rebuttals a patentee might raise (and their weakness)

• "Teaching away." One could argue the HP light‑tube patents teach that stray light must be blocked by tubes, i.e., away from the claimed "no blocking aperture" (claims 8/16). Weak: teaching away requires the reference to criticize the claimed approach; US 5,430,306 instead teaches designing for imprecision optically, which is consistent with the claimed approach. At most this creates a genuine dispute for claims 8 and 16.
• "Single focusing element" is not literally met by a lens cluster. US 5,856,833's lens is a multi‑portion molded cluster, and US 5,262,797's chip assembly may be composite. Weak: the specification defines "single focusing element" as "only one focusing operation… by surface 215," so the claim's scope is functional; and US 5,905,512/6,172,690 have literally a single lens 426.
• Secondary considerations. No evidence of record in the patent of unexpected results, licensing‑despite‑validity, long‑felt need, commercial success with nexus, or failure of others. If such evidence exists in the co‑pending litigation (Texas W.D., 6:19‑cv‑00364), it would need a nexus to the "single focusing element / translucent fill" limitation. On the current record, none is apparent.
• Priority/prior‑art status. All the strong HP references predate the July 2, 2001 filing (US 5,262,797 (1993), US 5,289,208 (1994), US 5,430,306 (1995), US 5,856,833 (1999), US 5,905,512 (1999), US 6,172,690 (2001‑01‑09)). US 6,172,690 issued Jan. 9, 2001, within one year of filing — it is § 102(a)/(e)/(b)‑eligible, and in any event its parent US 5,905,512 is comfortably prior art.

10. Bottom line

• Claim 1 — obvious over US 5,856,833 alone or in view of US 5,289,208.
• Claims 2–4 — obvious over US 5,262,797 (clear plastic in the lens‑to‑photodiode path) + US 5,856,833 (encapsulation/integral molding) + US 6,172,690 (polycarbonate body).
• Claim 5 — obvious over US 5,262,797 (optimum focal distance / fixed spacings) + US 6,172,690.
• Claims 6–7 — obvious over US 5,856,833 (shaped passage 72) and the HP phase‑plate family (EP 0 622 237) matching aperture to test‑pattern spacing. (Exact US counterpart number unconfirmed.)
• Claims 8 & 16 — most vulnerable to a non‑obviousness argument (negative "no blocking aperture" limitation that the HP light‑tube art approaches oppositely), but still likely obvious under the omission/known‑substitution rationales. This is where a validity challenge and any patentee response in the 6:19‑cv‑00364 litigation would most plausibly concentrate.
• Claim 9 — obvious over US 5,289,208 + US 5,856,833; claims 10–12 follow per above.
• Claim 13 — obvious over US 5,262,797 + US 5,905,512 / US 6,172,690; claims 14–16 follow.

Confidence statement. Claim 1's obviousness and the dependent claims turning on the translucent fill/aperture are supported with high confidence from the located reference text. The two lower‑confidence items are (i) the exact US identifier of the "phase plate/aperture matched to the mark" reference, which I did not verify in this session, and (ii) the outcome on claims 8/16, which turns on how a tribunal weighs a negative limitation against art that teaches the opposite. I have flagged both rather than assert them as settled.