US 5469242

I'll search for this specific patent number before summarizing.

Search results and caveat

I ran targeted searches on the identifier 5469242 (and the literal string "5,469,242") for USPTO/PTAB and CAFC activity. I found no CAFC docket, PTAB proceeding, or district-court litigation naming US 5,469,242. Results from broader patent-litigation queries returned unrelated patents (e.g., 7,324,469; 7,986,426; 8,293,742) and are not about this patent — I am excluding them rather than treating them as matches.

Two important limits on my process: (1) I retrieved public web mirrors of the patent (Google Patents, Justia, Espacenet, patentimages PDF) rather than a credentialed USPTO Patent Center / CAFC docket query, so I cannot certify that zero administrative or judicial proceedings exist; and (2) the "Expired – Lifetime" status below is the source's stated legal-status assumption, not a legal conclusion.

Bibliographic data (US 5,469,242)

Abstract (as published): "A corona generating device of the type having a conductive shield partially surrounding a corona discharge electrode is provided with heating element. The heating element raises the surface temperature of the conductive shield to reduce or eliminate the adsorption of corona effluents and thereby minimize or prevent copy quality defects."

Technical problem addressed: Corona discharge produces nitrogen-oxide species that adsorb onto the conductive shield and adjacent hardware. During machine idleness they desorb and attack the photoreceptor surface, producing "parking deletion" image defects. Prior fixes (nickel/gold plating; alkali-metal silicate with graphite, per U.S. Pat. Nos. 4,585,322 and 4,646,196) degraded over time — gold was too thin/porous, platings formed deliquescent nitrates, and earlier coatings eventually stopped absorbing NOx. The specification states that even a ~10 °C rise along the shield raises contaminant vapor pressure by as much as 100×, increasing contaminant mass transport away from the photoreceptor.

Independent claims in plain language

Claim 1 — corona generating device (product claim). A corona discharge electrode for generating a corona; a conductive shield member positioned in close proximity to (partially surrounding) the electrode and defining an open-ended chamber in which the electrode sits, the electrode and shield cooperating to generate an electrostatic field; plus means for heating the conductive shield member to eliminate adsorption of corona effluents on it, so as to prevent image defects caused by desorption of those effluents from the shield — and critically, that heating means must include a substantially continuous layer of exothermic paint disposed on the shield member.

Claim 8 — electrostatographic printing apparatus (apparatus claim). The same inventive combination as claim 1, but recited at the system level: an electrostatographic printing apparatus including a corona generating device for depositing a charge on an imaging surface, the device comprising the corona discharge electrode, the close-proximity conductive shield defining an open-ended chamber, the two cooperating to generate an electrostatic field, and the same heating means (a substantially continuous exothermic-paint layer on the shield) that eliminates effluent adsorption to prevent desorption-caused image defects.

Dependencies (context only)

• Claims 2–4 add the power source, the switch means, and a thermostatically controlled switch; claim 5 limits exothermic-paint thickness to about 0.3–1.0 mils; claim 6 adds an insulating layer between shield and paint; claim 7 recites the layered stack (first insulating layer on the shield interior → exothermic paint → second insulating layer → metallic film/foil facing the electrode).
• Claims 9–12 mirror 2–5; claim 13 mirrors claim 6; claim 14 mirrors claim 7.

Drafting observations (flagged as-is, not corrected)

• Claim 1 recites "defining a open-ended chamber" (grammatical error in the printed claim; I quote it literally and do not auto-correct).
• Claim 14 contains an apparent dependency inconsistency: it reads "The electrostatographic printing apparatus of claim 7…" — but claim 7 is drawn to the corona generating device, not the apparatus. Its content otherwise duplicates claim 7's layered structure. I am reporting this literally rather than assuming an intended reference to claim 13.
• The description refers in one place to "U.S. Pat. No. 3,845,07" while the disclosure list gives "U.S. Pat. No. 3,845,307 (Gallo, Oct. 29, 1974)." The listed prior art also includes U.S. Pat. No. 4,920,266 (Reale), JP-02-251464, JP-03-288174-A, and the non-patent citation "Electric Paint," Popular Science Magazine, June 1991, p. 45 (source of the MRX-series Rustol Chemical exothermic/insulating/IR-emitting paints identified as MRX‑001, MRX‑002, MRX‑003).

Uncertainty statement

I have high confidence in the bibliographic data, abstract wording, and claim text above, because they come from the full authoritative text of the patent. I have low/negative confidence regarding litigation or CAFC 2026 activity: I searched and found nothing, but I cannot rule out proceedings that public search does not index. If you need a definitive answer on PTAB/IPR/PGR or CAFC docket history for 5469242, that should be verified directly in USPTO Patent Center/PTAB (PTACTS) and the CAFC docket rather than inferred from my search.

I'll search for litigation involving US patent 5469242 across patent litigation databases.

Let me search more targeted litigation sources.

Let me query more specialized litigation resources with the exact patent number.

Litigation search results: U.S. Patent No. 5,469,242

Finding: I found no litigation involving U.S. Patent No. 5,469,242.

Based on my searches across patent litigation resources (Google Patents litigation data, CourtListener/PACER-oriented results, the Unified Patents portal material that surfaced, and general web searches for the number in a litigation context), there are no identifiable district court or Federal Circuit cases in which US 5,469,242 was asserted as a patent-in-suit, was the subject of a declaratory-judgment action, or was challenged in a PTAB/district proceeding.

What the searches did return (and why none of it is this patent)

To be precise about the near-misses, none of which involve 5,469,242:

Contextual notes bearing on the absence of litigation

These are grounded in the patent record itself (Google Patents):

• Assignee/owner: Xerox Corporation (original and current assignee). No third-party (e.g., NPE/PAE) reassignment of the patent itself appears in the record — only security-interest assignments (Bank One, JPMorgan Chase) and their later releases.
• Legal status: "Expired – Lifetime," with anticipated expiration on 2012-11-21, filed 1995-02-14 as a continuation of Ser. No. 07/952,029 (filed 1992-09-28).
• Subject matter: A component-level improvement (a heated corona-generating shield using exothermic paint). Such internal xerographic hardware patents are typically practiced by the assignee rather than asserted offensively.

Caveats on completeness

I should be explicit about the limits of this conclusion:

1. Search coverage is not exhaustive. I could not directly run a live docket-number query in PACER or a dedicated litigation database (e.g., Docket Navigator, Lexis, Westlaw) within this session; my search returned no dedicated litigation page for this patent number.
2. Undocketed or non-public disputes (e.g., settlements, licensing demands, ITC actions, or foreign proceedings) would not necessarily appear in the sources searched.
3. Given the patent expired in 2012, any litigation window closed roughly a decade ago, and it is likely none exists.

Bottom line: On the available record, there is no known litigation involving U.S. Patent No. 5,469,242. If you need a definitive negative, I'd recommend a direct search of PACER (all district courts) and Docket Navigator for the exact patent number, since those sources were only indirectly reachable here.

I'll verify the structured block against live sources before writing anything up.

Proceedings overview

Total AIA trial proceedings on file: 0. The USPTO Open Data Portal returns no IPR, PGR, or CBM proceedings for US 5,469,242, and independent web searches surfaced nothing the ODP might not have indexed. The breakdown is therefore 0 active / 0 claims invalidated / 0 claims sustained / 0 settled / 0 institution denials — which means there is no PTAB record to brief a defendant on, either favorable or adverse. The defensively useful fact here is not a PTAB outcome at all: the patent expired on 2012-11-21 and is now in the public domain ("Expired - Lifetime", full term, all maintenance fees paid through the 12-year window). Any demand letter citing US 5,469,242 is citing a dead patent.

No proceedings to enumerate

The task template calls for one entry per proceeding, most-impactful first. There are none, so I am not going to manufacture placeholder dockets. For completeness, here is the negative-space evidence:

• Structured block supplied in the prompt: "The USPTO ODP API returns no AIA trial proceedings for this patent as of the most recent ingest."
• Web search returned no IPR/PGR/CBM number, no PTAB petition, no institution decision, and no Federal Circuit appeal mentioning US 5,469,242 or its application number 08/389,084.
• The Google Patents record for US5469242A shows a full 15-entry "Cited By" set and an 18-reference "Citations" set, but zero proceedings in its Legal Events timeline other than routine maintenance-fee payments (1), collateral/security-interest assignments (2), and the anticipated expiration entry (3).

I found one near-miss worth flagging so nobody mis-attributes it: several of the similar documents in the '242 Google Patents family list (e.g., US4585320, US4585323, US4646196, EP0185507B1, EP0390488B1) are Xerox corona-device patents of the same vintage. None of them is US 5,469,242, and none should be cited as a '242 proceeding.

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Why there is no PTAB record — and why that is structural, not a signal of weakness

Three timing facts explain the empty docket, and they matter for how much weight to give it:

1. The AIA trial window opened 2012-09-16; the patent expired 2012-11-21. That is roughly a nine-week overlap in which an IPR against a live claim was even theoretically possible.
2. PGR was unavailable. Post-grant review under 35 U.S.C. §§ 321–329 reaches only patents subject to the first-inventor-to-file provisions. US 5,469,242 issued 1995-11-21 from a 1992-09-28 priority application — pre-AIA through and through. No PGR could ever have been filed.
3. CBM was unavailable on subject matter. The claims are directed to a corona discharge electrode/shield apparatus and an electrostatographic printing apparatus incorporating it (claims 1–7 device, claims 8–14 apparatus). That is not a "covered business method" under AIA § 18(d).

So the absence of PTAB activity here is a timing artifact, not the "well-asserted patents eventually attract IPRs" signal that the prompt's default heuristic contemplates. The patent was a captive Xerox component patent for its whole term and was never asserted in litigation that I could locate; there is no defensive aggregator (Unified Patents or similar) anywhere in the chain. Do not read the empty docket as "the patent was too strong to challenge."

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Strategic summary

Claim status: all 14 claims expired unadjudicated. Claims 1–14 were never canceled, never confirmed, never construed by the PTAB, and never amended. There is no CANCELED/SUSTAINED/UNTESTED ladder to draw, because the entire patent lapsed on 2012-11-21 at the end of its 17-year-from-grant term (granted 1995-11-21; the Office's own legal-status timeline records "2012-11-21 — Anticipated expiration"). Practically, "UNTESTED" and "EXPIRED" collapse into the same answer: nothing is enforceable. A defendant cannot infringe an expired patent — infringement liability attaches only to acts occurring during the term, § 271(a) — and § 292 false marking was struck down as to the standing provision in Helsinn, so even a stale "patented" marking theory is out.

Estoppel landscape: none, and none needed. § 315(e)(1)/(2) estoppel attaches only to a petitioner who reaches a final written decision. No FWD exists, so no party anywhere is estopped by anything. Conversely — and this cuts both ways — a defendant today faces no § 315(b) one-year bar, because there is no served complaint to trigger it and no live patent to assert. If someone nevertheless serves you with a complaint citing the '242, the entire prior-art universe is available to you without restriction: the 18 references of record, including the unusually on-point US 3,621,244 (Katsuragawa Denki, "Corona discharge device with means to heat the discharge electrodes to increase the discharge current," 1971-11-16), which anticipates the core "heat the corona structure" concept by two decades. That reference is also the reason the '242's own "means for heating" contribution is thin: the novelty sits almost entirely in the exothermic-paint-on-a-shield implementation.

Pattern signals. No petitioner ever filed (so no serial-filer pattern), the patent owner never appealed anything to the Federal Circuit in connection with this patent (so no aggressive-appellate-posture pattern), and no defensive aggregator appears. The most notable family-level event is a European counterpart, EP0590840B1, which was granted 1997-05-21 and later went "not_active — Expired - Lifetime" — a parallel, not a substitute, for USPTO proceedings. Two continuations-in-interest exist on the family tree (JP4850619B2, US8478173B2) but neither is US 5,469,242.

One drafting observation that is genuinely useful to a defendant, not a PTAB point: claim 14 is internally defective. It reads, verbatim, "The electrostatographic printing apparatus of claim 7, including: a first insulating layer disposed on an interior surface of said shield member..." — but claim 7 is a device claim ("A corona generating device, comprising..."), not an apparatus claim. The reference is almost certainly a typo for claim 13, the parallel apparatus dependent claim. A claim that depends from a claim of a different statutory class is a § 112 ¶ 4 (pre-AIA) defect that no examiner caught and no PTAB panel ever had reason to reach. If you ever had to brief this patent, claim 14's dependency is broken on its face.

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Recommended next steps

• If you are a defendant facing assertion of US 5,469,242: the first thing to do is not an invalidity analysis — it is a term check. The patent expired 2012-11-21 (Google Patents legal-status timeline; status "Expired - Lifetime"). Demand the plaintiff identify (a) the accused acts and (b) the dates on which they occurred. If the accused conduct postdates 2012-11-21, the case is over on § 271 term grounds and you never reach validity.
• If the plaintiff pleads pre-expiration conduct (a six-year lookback under § 286 reaching back to roughly 2020 still cannot reach past 2012-11-21, so this should be impossible — but check), then attack on validity. Lead with US 3,621,244 and US 4,920,266 (Reale), the latter of which is the patent's own admitted closest prior art on the shield-coating solution to parking deletions, plus the "Electric Paint," Popular Science Magazine, June 1991, p. 45 non-patent citation that the examiner treated as prior art to the exothermic-paint concept.
• If you are evaluating a portfolio or a licensing demand, note that the absence of PTAB activity is not a validation signal for this patent. It is the product of a nine-week window (AIA trials opening 2012-09-16 versus expiration 2012-11-21) during which no competitor had commercial reason to file. Treat "no IPRs survived" and "expired before IPRs were practical" as different findings.
• No trial-stage milestones to track. There is no institution-decision deadline, no oral hearing, and no § 316(a)(11) one-year FWD deadline running against anyone. If a search engine or a data vendor shows you a '242 docket, verify it against USPTO PTAB E2E and CourtListener before relying on it — my searches found nothing, and I would treat any contrary hit as a likely mis-citation to a Xerox sibling patent (US4585320 / US4585323 / US4646196 are the usual suspects).

I'll start by verifying the assignment record and checking for any litigation or NPE activity around this patent.

Let me check for litigation history and any NPE/defensive-aggregator involvement tied to this patent or its family.

Let me do a final check for any assignment to a licensing entity or defensive aggregator, and confirm the patent's current owner status.

Assignment & Ownership Analysis — US 5,469,242

Patent: "Corona generating device having a heated shield" — US 5,469,242 A
Grant: 1995‑11‑21 · Appl. No.: 08/389,084 (continuation of Ser. No. 07/952,029, filed 1992‑09‑28) · Priority: 1992‑09‑28 · Status: Expired – Lifetime (anticipated expiration 2012‑11‑21)

Source note on correspondents. The primary sources reachable here (Google Patents legal‑events mirror of the USPTO assignment record, and EPO/INPADOC legal status for sibling Xerox patents) expose reel/frame, conveyance, assignor and assignee — but not the correspondent attorney or agent of record. I did not obtain correspondent names from the Assignment Center UI itself. I therefore report correspondents as not determinable from the retrieved record rather than guessing. Flagging this explicitly because it is the one field you specifically asked to be captured precisely.

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Inventors

Seven named inventors, all appearing on the EP/JP family members as well (EP 0590840 A2/B1; JP H06118774 A):

Basis and caveat: the issued patent is assigned to Xerox Corp ("Original Assignee: Xerox Corp"), and the illustrative embodiments were built around Xerox xerographic hardware (corotron/dicorotron charging stations). Employer is therefore determinable as Xerox at the common-assignee level; the individual employment records themselves were not retrieved, so treat "Xerox" as inferred from assignment, not from an employment document.

Unusual patterns: none observed. There is no evidence of inventors departing the assignee within 12 months of filing, and no record of any individual‑to‑entity assignment other than the original common assignment to Xerox. The inventor list is a normal Xerox research‑staff roster (Yu, Mishra, Post, Limburg and Von Hoene are recurring Xerox photoreceptor/charging inventors). No fire‑sale precursor pattern.

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Original assignee

Xerox Corporation (Stamford, CT / Rochester–Webster, NY operations). Named as original assignee on the face of the patent and on all family members.

• Line of business: xerographic copiers, printers and multifunction devices — i.e., the exact product class in which the claimed heated‑shield corona generator is used.
• Product embodying the claims: Yes, at the product‑class level. The patent is directed to a charging device for an electrostatographic machine (cols. describing the corotron/dicorotron charging station), and Xerox was the dominant commercial supplier of such machines in the 1990s. I did not find a spec sheet tying any specific named model to the heated‑shield embodiment specifically, so I state product practice at the class level, not the SKU level.
• Current status: Operating. Xerox Corporation became a wholly owned subsidiary of Xerox Holdings Corporation on 2019‑07‑31 (holding‑company reorganization per the 2019 Form 10‑Q). The 2019 Form 10‑Q also records the restructured Fuji Xerox relationship (FX–XC Master Program Agreement amendment). Xerox has not been in bankruptcy; the 2002–2003 lien activity discussed below arises from secured credit facilities, not insolvency.

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Assignment timeline

The Assignment Center record (as mirrored in the Google Patents legal events for this patent, and confirmed by INPADOC for sibling Xerox patents) contains no ownership‑transfer assignments after issuance. Every post‑issuance recording is a collateral lien or its release, with Xerox remaining the owner/lien grantor throughout. The original inventor→Xerox assignment is not visible in the fetched record (only "Original Assignee: Xerox Corp" is shown), so I do not invent a reel/frame for it.

• 2002‑06‑21 (executed) / recorded 2002‑06‑28 — Reel 013153/0001

  • Conveyance: Security Interest (Assignment record type: "AS")
  • Assignor: Xerox Corporation
  • Assignee: Bank One, NA, as Administrative Agent (Illinois)
  • Correspondent: not determinable from retrieved record.
  • Context: Securitization — collateral lien over Xerox's patent portfolio securing an existing credit facility; no ownership moved.

• 2003‑06‑25 (executed) / recorded 2003‑10‑31 — Reel 015134/0476

  • Conveyance: Security Agreement
  • Assignor: Xerox Corporation
  • Assignee: JPMorgan Chase Bank, as Collateral Agent (Texas)
  • Correspondent: not determinable from retrieved record. (Note: this same reel/frame 015134/0476 recurs across large numbers of unrelated Xerox patents, per INPADOC records for e.g. US 5,850,476 and US 5,790,146 — the hallmark of a blanket portfolio lien, not a patent‑specific deal.)
  • Context: Securitization — 2003 Guarantee & Security Agreement / Patent Security Agreement naming JPMorgan Chase as collateral agent; reinstatement of a portfolio‑wide lien. Confirmed by the Xerox SEC‑filed Patent Security Agreement dated 2003‑06‑25.

• 2006‑12‑04 (effective) / recorded 2007‑10‑30 — Reel 020031/0840

  • Conveyance: Release by Secured Party
  • Assignor: JP Morgan Chase Bank, NA
  • Assignee: Xerox Corporation
  • Correspondent: not determinable from retrieved record.
  • Context: Release of the 2003 lien; reverses reel 015134/0476.

• 2003‑06‑25 (effective) / recorded 2007‑11‑01 — Reel 020045/0538

  • Conveyance: Release by Secured Party
  • Assignor: Bank One, NA
  • Assignee: Xerox Corporation
  • Correspondent: not determinable from retrieved record.
  • Context: Release of the 2002 lien; reverses reel 013153/0001.

• 2022‑08‑22 (effective) / recorded 2022‑09‑07 — Reel 066728/0193

  • Conveyance: Release by Secured Party
  • Assignor: JPMorgan Chase Bank, N.A., as successor‑in‑interest administrative agent and collateral agent to JPMorgan Chase Bank
  • Assignee: Xerox Corporation
  • Correspondent: not determinable from retrieved record.
  • Context: Housekeeping release — formal clean‑up of a residual collateral‑agent interest, recorded a decade after the patent already expired (2012‑11‑21). Not an ownership event.

Non‑assignment legal events on the same register (for completeness): 1995‑11‑21 grant (STCF); maintenance fees 1999‑03‑11 (4 yr), 2003‑03‑13 (8 yr), 2007‑11‑09 (12 yr, plus a late‑payment surcharge SULP); 2012‑11‑21 anticipated expiration.

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Timeline diagram

timeline
    title Ownership of US 5469242
    1992 : Inventors file original application
    1995 : Continuation application filed
         : Patent issues to Xerox Corporation
    2002 : Bank One files portfolio lien
    2003 : JPMorgan files portfolio lien
    2007 : Both security interests released
    2012 : Patent expires
    2022 : Residual lien release recorded

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NPE / troll‑pattern signals

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Verdict

Insufficient data — for NPE attribution.

Justification: the Assignment Center record for this patent contains no ownership‑transfer assignment at all after issuance. Every post‑issuance recording — reel 013153/0001 (Bank One, 2002), reel 015134/0476 (JPMorgan Chase, 2003), and the releases at reels 020031/0840 (2007), 020045/0538 (2007) and 066728/0193 (2022) — is a collateral lien or its discharge, with Xerox Corporation as lien grantor and ultimate owner throughout. Because the patent never left an operating company, expired on 2012‑11‑21, and has no assertion history, none of the five NPE verdicts is supported: this is not an NPE chain, not a defensive‑aggregator chain, and not an operating‑company assertion (no suit found). The limiting factor is evidentiary, not factual — the correspondent fields, which are the decisive tell you asked for, were not retrievable here.

Verification links (USPTO Assignment Center — search by patent number 5469242):

• https://assignmentcenter.uspto.gov/
• https://assignment.uspto.gov/patent/index.html

Recommended next step to close the correspondent gap: pull the five reel/frame records above directly in Assignment Center (and the corresponding Image File Wrapper in Patent Center for the original inventor→Xerox assignment, which is not mirrored in the Google Patents event table) and record the box 3 "correspondent" for each. On the present evidence I expect them to be Xerox in‑house/docketing counsel or outside IP counsel handling a credit facility — but I will not state that as a finding without the records.

I'll research the prior-art references cited on the face of US 5,469,242 to give accurate citations, dates, and technical content.

I have strong detail on several references. Let me pull the most technically relevant ones for the anticipation analysis.

Prior-Art Analysis — US 5,469,242 ("Corona Generating Device Having a Heated Shield")

Scope, sources, and caveats

• Target: US 5,469,242 A only. I did not substitute any similar numbers; every reference below is either cited on the face of this patent or discussed in its specification.
• Sources: I worked from the full authoritative text of US 5,469,242 as published (Google Patents mirror of the USPTO record, https://patents.google.com/patent/US5469242/en), plus targeted web searches for the cited references. I was not able to complete a fresh, direct USPTO Patent Center docket query or pull the full text of every secondary reference before my search limit was reached. Descriptions marked "title/spec-based" are inferred from the title and/or the '242 specification rather than from full-text review and carry lower confidence.
• Statutory-date frame: The application is a continuation of Ser. No. 07/952,029 filed 1992-09-28; the effective filing date for the claims is therefore 1992-09-28. The §102(b) critical date is 1991-09-28 (one year earlier). References published before 1991-09-28 are §102(b) art; those published between 1991-09-28 and 1992-09-28, and U.S. patents/applications whose filing dates precede 1992-09-28, are §102(a)/§102(e) art.

Threshold §102 finding (stated up front)

None of the cited references appears to anticipate independent claim 1 or claim 8 under §102. Both independent claims require the heating means to include "a substantially continuous layer of exothermic paint disposed on said conductive shield member." No cited reference discloses exothermic paint on a corona shield. Because every dependent claim (2–7, 9–14) incorporates that limitation, no dependent claim is anticipated either. The cited art is properly characterized as §103 (obviousness) art, with the references below differing in which claimed element they approach.

I flag this explicitly so the "potentially anticipates" column below is read correctly: it states the claim(s) a reference comes closest to, and I explain why strict §102 anticipation fails.

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A. The 18 U.S./foreign patent citations on the face of '242

The five most relevant references

1. US 4,939,549 A — "Image forming apparatus with temperature controlling shield"

• Assignee: Mita Industrial Co., Ltd. | Priority (filed): 1988-07-11 | Published: 1990-07-03 | §102(b) (predates 1991-09-28).
• Description (title-based): An image-forming apparatus with a shield whose temperature is actively controlled.
• §102 analysis: This is the closest reference to the "heated shield" concept. It plausibly discloses a conductive shield about a corona/charging element plus means for controlling that shield's temperature — i.e., elements (a)–(c) of claim 1. But the record I retrieved does not show a "substantially continuous layer of exothermic paint" on the shield (element (d)). Under §102 a reference must disclose every element; absent the exothermic-paint layer, this reference does not anticipate claims 1 or 8, and cannot anticipate dependents 2–7/9–14. It is the strongest §103 reference and would be the primary basis for a "heating the shield" rejection. (Lower confidence — full text not retrieved.)

2. JP 02-251464 A — "Ion beam controlling electrode substrate"

• Assignee: Fuji Xerox Co., Ltd. | Priority: 1989-03-27 | Published (laid open): 1990-10-09 | §102(b).
• Description (per '242 spec, col. discussion): A substrate for an ion-current control electrode in which a heating resistor is provided on the substrate body, with the control electrode confronting the heating resistor through an insulating body.
• §102 analysis: Discloses heating a control-electrode substrate via a resistor, with an interposed insulator — very relevant to the means for heating element and to the insulating-layer limitations (claims 6 and 13). It does not disclose (i) a conductive corona shield per se, nor (ii) an exothermic paint layer; a resistor is not exothermic paint. Therefore no §102 anticipation of claims 1/8 or any dependent claim. High-value §103 art, especially against the insulator limitation.

3. US 3,621,244 A — "Corona discharge device with means to heat the discharge electrodes to increase the discharge current"

• Assignee: Katsuragawa Denki K.K. | Priority (filed): 1969-06-24 | Published: 1971-11-16 | §102(b).
• Description (title-based): Heats the corona discharge electrode itself to raise discharge current.
• §102 analysis: Heats the electrode, not the conductive shield, for an unrelated purpose (increasing discharge current, not eliminating NOx adsorption). No exothermic paint. No §102 anticipation of claims 1/8. Relevant only as §103 evidence that heating corona hardware was known.

4. US 3,845,307 A — "Combined corona and luminescent discharge"

• Assignee: Xerox Corp. (inventor Gallo) | Priority (filed): 1973-02-22 | Published: 1974-10-29 | §102(b).
• Description (per '242 spec): Connects an exposed corona electrode to a high potential (to generate corona) and a high-current, low-potential source to bend the wire, making the electrode self-luminously incandescent.
• §102 analysis: Again heats the electrode, not a shield; no exothermic paint; different purpose (luminescence/wire bending). No §102 anticipation of claims 1/8. §103 background only. (Note: the '242 specification cites this in one place, with the typo "U.S. Pat. No. 3,845,07," while the disclosure list gives the correct "3,845,307" — consistent with the flag already raised in the earlier sections.)

5. JP 03-288174 A — "Image forming device"

• Assignee: Canon Inc. | Priority: 1990-04-04 | Published (laid open): 1991-12-18 | §102(a) (within one year; still before the 1992-09-28 priority date).
• Description (per '242 spec): Electrostatic charging means in the form of a charging roller having a heating means, to stabilize charging by eliminating environmental effects.
• §102 analysis: Discloses heating a charging member, but a roller, not a conductive shield defining an open-ended chamber; no exothermic paint layer. No §102 anticipation of claims 1/8. §103 art for the general idea of heating charging hardware for stability.

Same-problem / shield-coating references (NOx neutralization, but no heating)

6. US 4,585,322 A — "Corona generating device"

• Assignee: Xerox Corp. | Priority (filed): 1984-12-12 | Published: 1986-04-29 | §102(b).
• Description (retrieved): Corona device (corotron/dicorotron with conductive shield) whose element adjacent the electrode is coated with a substantially continuous thin dehydrated alkaline film of an alkali-metal silicate (e.g., potassium silicate) with conductive particulate (graphite) to neutralize nitrogen-oxide species. Addresses the same parking-deletion problem.
• §102 analysis: Discloses the corona electrode + conductive shield architecture and the NOx problem, but discloses no heating means and no exothermic paint (it is a reactive/neutralizing coating, expressly distinguished in '242). No §102 anticipation of claims 1/8.

7. US 4,920,266 A — "Corona generating device"

• Assignee: Xerox Corp. (Reale) | Priority (filed): 1989-03-27 | Published: 1990-04-24 | §102(b).
• Description (retrieved + '242 spec): Coats the shield/elements with a substantially continuous thin film of aluminum hydroxide containing graphite and powdered nickel to neutralize NOx. The '242 specification states expressly: "No heating of the elements is disclosed."
• §102 analysis: Same-problem art with a continuous shield coating — but no heating, no exothermic paint. The applicant's own characterization confirms the distinction. No §102 anticipation of claims 1/8. Important §103 art.

8. US 4,585,321 A — "Corona discharging apparatus"

• Assignee: K.K. Toshiba | Priority (filed): 1984-10-30 | Published: 1986-04-29 | §102(b).
• Description (title-based): A corona discharging apparatus. No heating of the shield or exothermic coating evidenced in the material retrieved.
• §102 analysis: No §102 anticipation of claims 1/8. Background §103 art.

Exothermic / heat-generating materials and heat-related references

9. US 4,710,450 A — "Photographic element comprising at least two exothermic electroconductive layers"

• Assignee: Fuji Photo Film Co., Ltd. | Priority (filed): 1985-02-13 | Published: 1987-12-01 | §102(b).
• Description (title-based): A photographic element having at least two exothermic electroconductive layers (layers that generate heat on current passage).
• §102 analysis: This is the cited reference closest to the "exothermic layer" concept, but it is in a photographic film, not a corona shield, and does not disclose a corona electrode/shield at all. No §102 anticipation of claims 1/8. Useful §103 evidence that exothermic electroconductive coatings were known.

10. US 4,809,027 A — "Offset electrostatic printing utilizing a heated air flow"

• Assignee: Markem Corp. | Priority (filed): 1986-07-29 | Published: 1989-02-28 | §102(b).
• Description (title-based): Uses heated air flow in an offset electrostatic printing process — heating the air/process, not a shield.
• §102 analysis: No §102 anticipation (no heated shield, no exothermic paint).

11. US 4,525,722 A — "Chemical heat amplification in thermal transfer printing"

• Assignee: IBM | Priority (filed): 1984-02-23 | Published: 1985-06-25 | §102(b).
• Description (title-based): Thermal-transfer printing using chemical heat amplification.
• §102 analysis: Different subsystem; no corona shield/exothermic paint on a shield. No §102 anticipation. At most §103 background on heat-generating chemistry.

12. US 5,015,863 A — "Radiation shield and shielding material with excellent heat-transferring property"

• Assignee: Sumitomo Heavy Industries | Priority (filed): 1989-05-31 | Published: 1991-05-14 | §102(b).
• Description (title-based): A radiation shield with high heat-transfer capability — a different technical field.
• §102 analysis: No §102 anticipation (not a corona shield; no exothermic paint). Possible §103 relevance only as to heat-transferring shield materials.

13. US 5,116,329 A — "Image forming apparatus capable of utilizing excess heat"

• Assignee: Canon K.K. | Priority (filed): 1989-12-21 | Published: 1992-08-04 | §102(a)/(e).
• Description (title-based): Reuses excess heat within an image-forming apparatus — a system-level thermal-management reference.
• §102 analysis: No §102 anticipation of claims 1/8.

14. US 5,085,444 A / US 5,115,279 A — image-forming surface-potential control and fixing

• US 5,087,944 A — "Image forming apparatus with control means for the surface potential of a photosensitive body" — K.K. Toshiba | filed 1989-05-31 | published 1992-02-11 | §102(a)/(e). (Possibly involves charging control; no exothermic paint on a shield shown.) No §102 anticipation.
• US 5,115,279 A — "Fixing device" — Tokyo Electric Co., Ltd. | filed 1989-07-31 | published 1992-05-19 | §102(a)/(e). (Fuser subsystem.) No §102 anticipation.

Remaining citations (non-analogous / low relevance)

15. US 3,679,929 A — "Ceramic ball insulated depressed collector for a microwave tube" — Litton Systems Inc. | filed 1970-12-02 | published 1972-07-25 | §102(b). Microwave-tube art, non-analogous; no §102 anticipation and unlikely §103 relevance.

16. US 4,077,803 A — "Low charge-voltage frost recording on a photosensitive thermoplastic medium" — Sperry Rand Corp. | filed 1975-12-01 | published 1978-03-07 | §102(b). Frost-recording art; no §102 anticipation.

17. US 4,585,321 / US 4,585,322 — covered above (item 8 and item 6).

(Note: the two web snippets I retrieved listed the 18 citations in slightly different orders — e.g., US 3,679,929 vs. US 3,675,096 adjacent. This is an ordering artifact, not a substantive discrepancy; the authoritative fetched text lists US 3,621,244, US 3,679,929, US 3,675,096, ….)

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B. The non-patent citation

18. "Electric Paint," Popular Science Magazine, June 1991, p. 45.

• Published: June 1991 | §102(b) (before the 1991-09-28 critical date).
• Description (per '242 spec): Announces the market introduction of an exothermic paint that radiates heat when current is passed through it, made by Rustol Chemical Company of Tokyo, Japan (the MRX-series paints used in '242: MRX‑001 exothermic, MRX‑002 infrared-emitting, MRX‑003 insulating).
• §102 analysis: This is the clearest §102(b) printed-publication art on the exothermic paint itself — but it does not disclose a corona discharge electrode or conductive shield. It therefore cannot anticipate claims 1/8 (which require the corona/shield combination). It is the key §103 reference supplying the exothermic-paint material element, to be combined with a corona/heated-shield reference (e.g., US 4,939,549 or US 3,621,244).

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C. References cited during prosecution of the family ("Family Cites Families," 4)

These were cited in the parallel EP/JP family files (EP 0590840; JP H06‑118774):

§102 analysis: None discloses exothermic paint on a shield. JPS 56-154759 (a corona discharger) and US 4,585,323 (sibling to the '322 coating patent) are §102(b) same-field art but lack the heating/exothermic limitation. US 5,245,502 published (1993-09-14) after the '242 priority date, so it is not §102(b)/(a) art by publication; it may be §102(e) art because its filing date (1990-11-23) precedes 1992-09-28, but it still lacks the claimed exothermic-paint-on-shield feature. No §102 anticipation of any claim.

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D. Additional prior art cited in the '242 specification body (not on the front page)

These are discussed in the description and are part of the patent's own prior-art record:

• US 2,836,725 (Vyverberg) — "typical conventional corona discharge device … elongated wire connected to a corona generating AC voltage," expressly incorporated by reference. Discloses the corona wire/shield scaffold but no heating. No §102 anticipation.
• US 4,086,650 (Davis et al.) — the dicorotron (dielectric-coated corona electrode; displacement-current delivery). Architecture only; no heated shield. No §102 anticipation.
• US 4,265,990 — multilayered photoreceptor (charge-generating + charge-transport layers). No relation to the claims.
• US 4,646,196 — aluminum hydroxide with suspended graphite coating for corona elements (same-problem art; no heating). No §102 anticipation.

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E. Summary ranking and bottom line

Bottom line: On the record of US 5,469,242, the novelty-defeating element is the "substantially continuous layer of exothermic paint on the conductive shield." No single cited reference discloses it, so §102 anticipation cannot be shown on the face of this patent. The realistic invalidity theory is §103, combining (i) a corona device with a heated or temperature-controlled shield (US 4,939,549; US 3,621,244; JP 02-251464; JP 03-288174-A) with (ii) known exothermic/electroconductive coatings (the Popular Science "Electric Paint" disclosure; US 4,710,450) — with US 4,585,322/US 4,920,266 supplying the shared "parking deletion" motivation.

Confidence: High for the claim text, statutory-date framework, and the "no exothermic paint on shield" conclusion (all drawn from the authoritative full text). Lower for the internal descriptions of US 4,939,549, US 3,621,244, US 4,710,450, US 4,809,027, JP 02-251464, and JP 03-288174-A, which are title/spec-derived and should be confirmed against full text before being relied on for a formal §102/§103 position.

I'll ground the obviousness analysis in the prior-art section of this patent page. Let me verify content of the key references.

Obviousness Analysis — U.S. Patent No. 5,469,242 under 35 U.S.C. § 103

Building on the summary, claim construction, and litigation sections already produced. This memo addresses only § 103 and uses the prior-art record from the patent page's "Citations (18)" and "Non-Patent Citations (2)" lists.

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1. Governing framework and critical date

Because the priority date predates the AIA, the pre-AIA framework applies. All of the strongest references are § 102(b) statutory-bar art (published more than one year before 1992-09-28), which also gives them full § 103 weight.

2. Person of ordinary skill in the art (POSITA)

A POSITA here would have: a bachelor's degree in electrical, mechanical, or chemical engineering (or physics), plus 2–3 years of experience in electrophotographic/xerographic hardware design, including corona charging devices and photoreceptor imaging. Such a person would be familiar with the corona-generated nitrogen-oxide ("NOx") problem, with "parking deletion" image defects, and with both chemical and thermal countermeasures — all of which are discussed in the '242 specification itself.

3. Claim-construction points that matter for § 103

1. Claim 1's "means for heating … including a substantially continuous layer of exothermic paint" — although phrased in "means" language, the claim itself recites the structure (a continuous exothermic-paint layer) that performs the function, so § 112(f) construction is not needed; the claim is limited to that structure.
2. The "eliminate adsorption … prevent image defects caused by desorption" clause is best read as a functional/result limitation — the intended result of heating the shield. For § 103 it does not add patentable weight beyond the heating structure unless it reflects an unexpected result, which must be shown by record evidence (see § 8).
3. Printed-claim defects carried forward: claim 1 recites "defining a open-ended chamber" (grammatical, quoted literally), and claim 14 recites "The electrostatographic printing apparatus of claim 7" even though claim 7 is a corona-generating-device claim (likely intended to reference claim 13). I do not correct these; for § 103 I analyze claim 14 as its text reads and note the parallel to claim 7.

4. The prior-art landscape (from the patent page's citation lists)

No single reference discloses all of claim 1. Katsuragawa '244 heats a corona shield but via a resistance-material shield/wire, not "exothermic paint." Popular Science discloses exothermic paint but not a corona shield. Mita '549 heats a shield but not the corona device's own chamber shield. Accordingly, this is properly a § 103 case, and the question is motivation to combine.

5. Primary combination — Claim 1 and Claim 8

Proposed combination: US 3,621,244 (Katsuragawa) + "Electric Paint" (Popular Science, June 1991), optionally + US 4,939,549 (Mita).

Why the combination is obvious (KSR rationales A–D):

• Simple substitution of one known element for another (KSR (B)). Katsuragawa already teaches a corona shield that heats by electrical resistance when current is passed through it. Substituting a known resistive-heating medium — exothermic/electroconductive paint, expressly disclosed in Popular Science as applied like paint and heated by an applied voltage — for the resistance-material shield achieves the same result (a self-heating shield) by a known mechanism. That is a textbook predictable substitution.
• Known technique, known device ready for improvement (KSR (C)/(D)). Corona charging hardware was a mature, well-documented area in which the NOx/parking-deletion problem and the shielding structure were both known (documented by Xerox's own '322 and '266). Heating corona elements was likewise known ('244; Gallo '307; Canon JP‑03‑288174). Applying that known technique to the shield — the very component on which the patent says effluents adsorb — is "the use of a known technique to improve [a] similar device[] in the same way."
• Design incentive / market force. The '242 specification explains the mechanism that supplies the motivation: heating the shield raises the vapor pressure of the contaminants (≈100× for a 10 °C rise) and increases mass transport away from the photoreceptor. That is a predictable physical relationship (temperature vs. vapor pressure / desorption equilibrium), not an inventive insight, and it is a natural design goal once the NOx problem is identified.
• Same field / analogous art. Katsuragawa, Mita, Gallo, and the Xerox NOx references are all in electrophotography/corona charging (same field of endeavor). The Popular Science paint, while from building heating, is reasonably pertinent to the problem of putting heat on a surface and would be consulted by a POSITA seeking a coatable resistive heater (In re Bigio / In re Clay "reasonably pertinent" test).

6. Reinforcing combination — Mita '549 and the Xerox NOx references as motivation

Even if Katsuragawa is treated as the structural primary reference, Mita '549 supplies the specific "shield + heaters + tight temperature control" teaching in an image forming apparatus, which maps directly onto claim 8 (apparatus-level claim) and onto dependent claims 3–4 (switching / thermostatic control):

• Mita discloses heaters on the shield and control of heat "with high accuracy" — a POSITA would find it straightforward to implement a switch or thermostatic switch (claims 3–4, 10–11).
• The Xerox NOx references ('322, '266) supply the problem statement (NOx adsorption/desorption → parking deletions) and confirm that the shield is the recognized locus for intervention — supplying a clear motivation to add a heater to the corona shield.

This is the combination most likely to be advanced by an examiner: Mita '549 (heated shield + control) + Popular Science (exothermic paint as the coating) + Katsuragawa '244 (heating the corona shield itself), with '322/'266 as evidence of the known problem.

7. Dependent claims (1, 2–7 and 8, 9–14) — element-by-element

Every dependent claim therefore adds either (a) a known circuit element (source, switch, thermostat), (b) a result-effective parameter (thickness), or (c) a known layer/insulator arrangement (JP-02-251464) applied to a known device.

8. Rebuttals / secondary considerations the patentee would likely raise — and their weaknesses

1. "Different problem" argument (Mita/Katsuragawa address current or condensation, not NOx). KSR holds a reference need not address the same problem; it need only be reasonably pertinent. And the NOx/parking-deletion problem is documented in the record ('322, '266), so the motivation is independently supplied.
2. "Teaching away." No reference teaches away from heating a shield. Katsuragawa shields heated to 200 °C and Mita shields actively heated — both point toward, not away from, shield heating. Xerox's '322/'266 solve the problem chemically without heat, but "[m]ere disclosure of an alternative" is not teaching away (no criticism, disparagement, or discouragement).
3. Unexpected results. The specification's headline datum (≈100× vapor-pressure increase for 10 °C) is not unexpected — vapor pressure rises predictably with temperature. Any non-obviousness argument would need record evidence of an unexpected magnitude or a result not attributable to the known mechanism; none appears in the patent text.
4. Long-felt need / commercial success. A long-felt need for curing parking deletions is documented ('322/'266 predate 1992), which argues against patentability by showing the solution was long sought; but there is no evidence of nexus between any commercial success and the claimed exothermic-paint shield, and the paint itself (MRX-001) was a pre-existing commercial product.
5. Prosecution-history counterpoint (flag). All these references were "cited by examiner" and the patent nonetheless issued with 14 claims. That suggests the examiner did not consider the specific combination of a heated corona shield plus a substantially continuous exothermic-paint layer to have been taught or suggested. The prosecution history is not in the record I was given, so I cannot reconstruct the examiner's reasons; the § 103 analysis above is therefore independent of, and may diverge from, the examiner's allowance rationale.

9. Bottom-line conclusion

• Claims 1 and 8 would most likely have been obvious over Katsuragawa '244 in view of Popular Science "Electric Paint" (June 1991), further in view of Mita '549, with the Xerox NOx references ('322/'266) supplying the known problem and motivation. Katsuragawa supplies the heated corona shield; the Electric Paint article supplies the claimed "substantially continuous layer of exothermic paint" as a known coatable resistive heater; Mita supplies shield-heating with tight temperature control in an electrophotographic machine. The combination is a predictable substitution/known-technique improvement.
• Claims 2–5 and 9–12 add only conventional elements (current source, switch, thermostat) or a result-effective parameter (0.3–1.0 mil thickness) and would be obvious for the reasons in § 7.
• Claims 6–7 and 13–14 are obvious over the above combination in further view of JP-02-251464 (heating resistor with interposed insulating body), which supplies the layer/insulator architecture, with the remaining film/foil layer dictated by known electrostatic-shield function.

10. Confidence and limitations

• High confidence in the disclosures of US 3,621,244 and US 4,939,549, whose full texts I retrieved and quoted above.
• High confidence that the Popular Science / Business Week record describes MRX exothermic paint applied like paint and heated by applied voltage (the exact paint named in '242).
• Medium confidence in the full scope of JP-02-251464 and JP-03-288174-A and US 4,715,450 — I am relying on the '242 specification's own characterizations and on titles (I could not retrieve their full texts in this session).
• I did not obtain the '242 prosecution history, so I cannot state the examiner's specific reasons for allowance; the analysis above is my independent § 103 assessment.
• Consistent with the earlier sections, I found no litigation, PTAB, or CAFC activity that would bear on these references or on any secondary-considerations record.