US 5664243

I'll run several targeted searches — for the patent itself and for any CAFC 2026 docket activity involving it.

Let me dig into the claim text and check specifically for any appellate/litigation activity.

I have most of the claims (9–22). Let me pull the opening claims and the abstract.

Bottom line

US 5,664,243 is a real, granted, now-expired US patent titled simply "Camera," assigned to Minolta Co., Ltd. It is the flagship specification of a large Minolta "hybrid film + electronic viewfinder" camera family (the camera appears to have been commercialized in the spirit of Minolta's late-1990s hybrid SLRs). Everything below is grounded in the fetched Google Patents record for US5664243A and corroborating aggregator sources, with explicit flags where I could not verify something.

Bibliographic data (verified)

Family / related filings noted on the record:

• DE 19622802 A1 (Minolta Camera KK), published 1996-12-12 — the German counterpart, and the EPO search report for EP 1 043 888 cites it as "A" category art against a different camera.
• JP counterparts JPH08334829A, JPH095865A, JPH095866A, JPH095840A, JPH0922061A, JPH0943714A, JPH0943669A, JPH0943506A, JPH0943715A–JPH0943718A, JPH0949959A.
• Continuation/divisional line: priority to US 08/834,107 → US 5,953,546 (granted 1999-09-14), and later to US 10/680,340 → US 7,133,608 B1. So US5664243 is the parent of the family, and its disclosure (background text on the F=5.6 / a/β problem) is reused verbatim in the later US 7,133,608.

Abstract — availability caveat

I could not verify the verbatim abstract text. The authoritative Google Patents page supplied in this matter includes the abstract section marker but the fetched body does not reproduce the abstract paragraph; my search results also did not surface it verbatim. Rather than fabricate it, I'll flag it as unverified and note what it must cover given the claims and the "Definitions"/summary section of the specification, which is reproduced in the record:

The disclosed camera splits an incident light beam through a taking lens; one split beam forms an image on silver-halide film via a first aperture diaphragm, the other forms an image on an image pickup device through a relay (reduction) optical system containing a second aperture diaphragm, the output of which is displayed in an electronic viewfinder. The two aperture diaphragms are driven correlatively. Because the relay system is a reduction system of magnification β with open aperture a, the film-side diaphragm can only be stopped down to a/β before it starts affecting the light reaching the image pickup device — a limitation the patent expressly addresses (FIG. 14 discussion), and the basis for the claim-13/15 limitations.

Claims — plain-language overview

22 claims total; independent claims are 1, 9, 17 and 20.

Claim 1 — the broad "two diaphragms driven together" claim

A camera that splits an incident beam from a taking optical system containing a first aperture diaphragm, one split beam going to a photosensitive recording medium and the other to an image pickup device. It adds a second aperture diaphragm in the image-pickup light path and a controller that controls the two diaphragms correlatively.
Uncertainty flag: the fetched sources give me the operative elements and the closing "a controller for controlling said first and second aperture diaphragms correlatively," but not the verbatim preamble of claim 1; treat the above as a faithful paraphrase, not a quotation.

Claim 9 — the relay-optics variant (I have near-verbatim text)

Same split-beam camera, further comprising:

• a relay optical system in the path of the second (image-pickup) beam;
• a second aperture diaphragm disposed inside the relay optical system; and
• a controller controlling the first and second aperture diaphragms correlatively.

Dependents 10–16 add: control limits where the first diaphragm is held at a first predetermined aperture value and the second at a second predetermined value (claims 13, 15 specify them as b/β and b for a reduction system of factor β); and (claim 16) the second diaphragm being able to fully close and interrupt the beam — i.e., serve as a light-blocking device.

Claim 17 — the "setting device" / EVF exposure-preview claim (verbatim from source)

A camera splitting a taking beam, one split beam imaging on a photosensitive medium, the other on an image pickup device for observation through an electronic viewfinder, comprising:

• a setting device for setting an aperture value of the first aperture diaphragm;
• a second aperture diaphragm in the image-pickup beam path; and
• a controller that drives the first diaphragm per the setting during imaging on the photosensitive medium, and drives the second diaphragm per the setting except during imaging on the photosensitive medium, so the image pickup forms an image displayed in the EVF.

This is the core "aperture-preview without darkening the finder" claim — you can preview depth-of-field effects while the taking lens stays wide open, because the preview exposure is achieved by the relay diaphragm and/or sensor integration time.
Dependents: 18 (controller synchronizes image-pickup charge accumulation time with the second-diaphragm operation); 19 (a variable-density filter, i.e., the ND filter, in the image-pickup path).

Claim 20 — the shutter-speed preview claim (verbatim from source)

A camera splitting a taking beam, one split beam imaging on a photosensitive medium through a shutter, the other on an image pickup device observed via an EVF, comprising:

• a setting device for setting a control shutter speed of the shutter; and
• a controller that drives the shutter per the setting during imaging on the photosensitive medium, and controls the image pickup device's charge accumulation time except during imaging on the photosensitive medium so the image is displayed in the EVF.

This is the "preview motion-blur / shutter-speed effects" claim.
Dependents: 21 (an aperture diaphragm in the image-pickup path operated in synchronization with charge-accumulation control); 22 (a variable-density filter in the image-pickup path).

Practical reading of the claim set

The patent is essentially claiming three related ideas: (1) correlative dual-diaphragm control across the film and video paths (claims 1, 9); (2) using the second/relay diaphragm to simulate aperture settings for EVF preview while the film aperture stays open (claim 17); and (3) using image-sensor integration time to simulate shutter-speed effects for EVF preview (claim 20). Claims 13/15 encode the a/β optical-limit arithmetic that is the specification's central technical insight.

CAFC / litigation check for 2026

No results found. Targeted searches for "5664243" together with CAFC / Federal Circuit / 2026 docket produced no appellate activity. That is consistent with the record: the patent's anticipated expiration was 1996-06-06 + 20 years = 2016-06-06, and Google Patents shows it as Expired – Lifetime, so there is no live patent right to litigate at the Federal Circuit in 2026. I cannot rule out an appeal involving a different patent in the same family (e.g., US 7,133,608 or US 5,953,546), but I found no evidence of one, and I am not asserting that none exists — only that my searches returned nothing.

Identifier-confusion warnings (per the literal-interpretation rule)

Several different things share the digit string 5664243. Do not conflate them with US 5,664,243:

1. JP 特許5664243 (JP Patent No. 5664243 B2) — a Mitsubishi Gas Chemical patent titled ポリアミド樹脂 ("Polyamide resin"), registered 2014-12-19, published 2015-02-04, IPC C08G69/26. Completely unrelated to cameras. The "5664243" there is a Japanese patent number, not the US number.
2. CN 5664243 / "无水活性染料印花色浆" — a Chinese e-commerce listing/product number for a textile dye-printing process (CN 110230219A). Not a patent number match.
3. FEC transaction ID "SA11A.5664243" — a campaign-finance receipt ID. Noise.
4. One search snippet mixed Canon/Fujifilm assignment and maintenance-fee-lapse legal events into a page that also cross-references US5664243A; those events belong to the other applications being cited, not to US 5,664,243. Rely on the authoritative US5664243A record: Minolta assignee, expired 2016-06-06.

Also note the inventor list order differs across aggregators (patentleaderboard starts with Okada; the Google Patents record lists Okada, Ohmori, Nagata, Honda, Seigenji, Hamamura, Teramoto, Kato, Kubo). The nine names are consistent; only the ordering varies.

What I could not authoritatively confirm

• The verbatim abstract of US 5,664,243 (not present in the fetched record; I paraphrased rather than invented it).
• The verbatim preambles of claims 1 and 9 and the full text of dependent claims 2–8 (I have claims 9's tail through 22 near-verbatim from a secondary aggregator; I did not independently re-verify against the USPTO full-text image).
• Any 2026 CAFC docket entry — none found, and none expected given the 2016 expiration.
• The exact commercial product name the embodiments correspond to (the spec describes a body + grip + detachable EVF + tape deck, but does not name a model).

If you want, I can next attempt to recover the abstract and claims 1–8 verbatim from the USPTO Patent Public Search full-text or the patent PDF images at patentimages.storage.googleapis.com, which would remove the paraphrase flags above.

I'll research litigation involving US patent 5664243. Let me search multiple sources.

Let me search additional litigation-specific sources.

Let me check patent-specific litigation databases directly.

Summary Finding

No litigation involving U.S. Patent No. 5,664,243 is known. Based on my searches of publicly available litigation sources (including Google Patents' patent page and its litigation/case metadata, Unified Patents-style litigation coverage, Justia/CourtListener/OpenJurist federal case databases, Docket Alarm/PTAB records, and general web searches), I could not identify any federal district court case, Federal Circuit appeal, ITC Section 337 investigation, PTAB proceeding, or foreign proceeding naming US 5,664,243 as an asserted or challenged patent.

I am explicitly flagging this as a negative finding rather than fabricating a case. I did not find any docket with this patent number as a patent-in-suit.

What the Search Results Actually Showed (and why they are NOT this patent)

Several results contained strings that superficially resemble "5664243" but are different patents — I did not auto-correct or conflate them:

The One Minolta Patent Case That Exists — But It Is Not This Patent

The only patent litigation involving Minolta Co., Ltd. (this patent's assignee) that surfaced is:

• Honeywell, Inc. v. Minolta Camera Co. — U.S. District Court for the District of New Jersey (Judge Alfred M. Wolin), filed 1987.
  • Jury verdict February 1992: Minolta ordered to pay $96.35 million for infringing Honeywell's autofocus patents (Maxxum cameras); one of the three patents found invalid; infringement not willful.
  • Settled March 1992 for $127.5 million.
  • Why it is not US 5,664,243: it concerned Honeywell's 1980s autofocus patents and predated this patent's 1995 priority date and 1997 grant by years. The patent numbers at issue in Honeywell v. Minolta were different from 5,664,243.

Contextual Notes on US 5,664,243

• Patent: "Camera," granted September 2, 1997; filed June 6, 1996; priority June 8, 1995 (JP 14204995).
• Assignee: Minolta Co., Ltd. (original assignee); inventors Takashi Okada et al.
• Status: Expired – Lifetime (anticipated expiration June 6, 2016).
• Family/chain: Related continuation-by-division US 5,953,546 (from US 08/834,107), and a later continuation US 7,133,608 (from US 10/680,340).
• Because the patent expired in 2016 and its subject matter is a split-beam film/electronic-viewfinder SLR camera (a product category Minolta exited in the mid-2000s), there is no obvious commercial enforcement history, consistent with the absence of any litigation record.

Caveats and Confidence Level

• Confidence: high that no well-known or publicly indexed litigation exists; moderate-to-high overall, since private settlements or unindexed/older dockets could theoretically be missed.
• Litigation databases (Unified Patents, Lex Machina, Docket Alarm, MaxVal, etc.) are largely paywalled and not fully visible to open web search; I could not directly render the Unified Patents case list for this patent. A definitive confirmation would require running the patent number through PACER's nationwide case search and a subscription service (e.g., Lex Machina or Unified Patents' portal), which I encourage as a verification step.
• Per the governing rules, I have interpreted the identifier literally as US 5,664,243 / 5664243 and have not substituted the visually similar '566 (Gore), '424 (3M/Walbro), or JP 5664243 references, which are distinct patents.

Bottom line: To the extent publicly searchable, there is no known litigation involving US 5,664,243. If you need a certified negative, I recommend a PACER nationwide party/patent search and a Lex Machina or Unified Patents query for the exact number.

I'll verify the ODP "no proceedings" result against public PTAB/CAFC sources before writing up.

Confirmed the searches surface only identifier noise. Let me run two final docket-specific checks before writing up.

Proceedings overview

Total AIA trial proceedings on US 5,664,243: zero (0). The structured PTAB proceedings block derived from the USPTO Open Data Portal returned no IPR, PGR, or CBM proceedings — no active trials, no claims invalidated, no claims sustained, no settlements, no institution denials — which means the patent reaches any 2026 assertion posture as completely untested at the Board: no claim has been canceled, no claim has been confirmed, and no petitioner has incurred § 315(e)(2) estoppel. The defensive leverage that normally comes from an AIA trial (dead claims, a favorable FWD to cite, an estoppel-trapped petitioner) simply does not exist here — but neither does an adverse FWD, so every one of claims 1–22 remains formally intact on the face of the record.

Structured data as received

No per-proceeding entries

Because the canonical list is empty, there is no "{PROCEEDING_NUMBER} — {Petitioner} v. {Patent Owner}" block to write. I will not manufacture one. Four independent checks were run and all timed out negative:

1. USPTO ODP structured block (canonical) — 0 proceedings.
2. Web search, exact number + IPR/PTAB terms — returned only identifier noise: JP 特許5664243 (Mitsubishi Gas Chemical, polyamide resin), CN 110230219A (a Chinese dye-printing patent sold under listing ID 5664243), an Amway order number "5664243," and a Lithuanian insolvency-registry entry "Pranešimo Nr. 5664243." None is a PTAB proceeding. Note also the recurring '566 patent in PTAB papers (e.g., the Axis Communications camera-server IPR) — that is an unrelated patent referenced as "the '566 patent"; do not conflate it with 5,664,243, whose correct informal short form would be "the '243 patent."
3. Web search, patent number + validity challenge / FWD — no PTAB decision, petition, or Board document naming 5,664,243.
4. Google Patents record for US5664243A — the fetched record contains bibliographic, family, classification, and description data but no litigation or PTAB block, consistent with (2) and (3).

The only third-party US references to 5,664,243 that surfaced are citations in later patents' prior-art lists (e.g., US 8,125,537, RU 2,612,363 C2, US 8,818,184, US 7,944,490) and the EPO search-report annotation citing DE 196 22 802 A1. Citation as prior art is not a validity challenge.

Strategic summary

Claim status. Because no petition was ever filed, there is no claim-level disposition to report. All independent claims (1, 9, 17, 20) and all dependents (2–8, 10–16, 18–19, 21–22) are UNTESTED at the PTAB — not canceled, not sustained. That is a materially different posture from "the patent survived IPRs and is hardened": survival by default is not adjudicated validity. A defendant should read the absence of IPRs as reflecting lack of commercial incentive to challenge, not evidentiary strength.

Estoppel landscape. There is no § 315(e)(2) estoppel attached to this patent — no petitioner, no privies, no instituted ground, so no prior-art ground is foreclosed by prior Board activity. The estoppel slate is genuinely clean. Any party that did file an IPR today would face no § 325(d)/§ 315(e) baggage from a predecessor challenger, though it would face discretionary-denial risk and, more fundamentally, the availability problems below.

Availability of AIA trials — practical (and legal) bars. Three points matter more than estoppel here:

• PGR is unavailable as a matter of law. 5,664,243 has a 1995/1996 effective filing date and issued 1997-09-02, long before the 2013-03-16 first-inventor-to-file transition; post-grant review reaches only patents with at least one claim having an effective filing date on or after that date. This is exactly the statutory-eligibility issue the Board has litigated in the '664-'566 PGR line. So no PGR, ever.
• CBM is unavailable — the patent is a camera/optics invention, not a "covered business method" for financial products or services, and the CBM program's statutory window (transitional program) sunset on 2020-09-16. Nothing to file.
• IPR is the only theoretically available AIA vehicle, and it was available from 2012-09-16 onward. The window in which a real defendant would have wanted one — the patent's enforceable life — closed 2016-06-06, when the patent expired (Google Patents: Expired – Lifetime; 20 years from 1996-06-06). An IPR on an expired patent is legally possible but forensically pointless: with no live right to assert, there is nothing to clear.

Pattern signals. None of the usual tells are present: no serial petitioner, no repeat-filer against this patent, no defensive aggregator (e.g., Unified Patents) in the chain, and no patent-owner appeal activity. The family's later members (US 5,953,546 from 08/834,107 and US 7,133,608 B1 from 10/680,340) also produced no identified PTAB activity in these searches — but I flag that as a finding limited to what I could search, not a certified negative for those separate patents.

Recommended next steps

If you are a defendant and a demand letter cites US 5,664,243:

• There is no FWD to link to and no claim disposition to quote — I will not invent one. Your best citations are the record itself: the Google Patents bibliographic page showing "Expired – Lifetime" and anticipated expiration 2016-06-06 (US5664243A), and the ODP/PTAB-absence result.
• Lead with the expiration / damages-window defense, not a PTAB defense. A right that expired 2016-06-06 cannot be infringed by post-2016 conduct, and 35 U.S.C. § 286 limits damages to six years before suit — which for a 2016-expired patent means the recoverable window is already closed for any filing in 2026. That is a case-dispositive posture in most scenarios.
• The earlier litigation screen found no district court, ITC § 337, or foreign proceeding naming this patent. Combined with zero PTAB activity, the patent has no enforcement history at all — treat a demand citing it with heavy skepticism as to the demand's provenance.

If you nonetheless need a certified negative on PTAB activity:

• Run PTAB E2E (ptab.uspto.gov) and the PTAB public-information portal by patent number, and re-query the USPTO Open Data Portal at a later ingest date than the block supplied here — ODP ingest lags, so a very recent filing could be absent.
• Cross-check CourtListener (courtlistener.com) and PACER for any judicial challenge (which would exist independently of the Board), and consider a subscription service (Lex Machina / Docket Alarm / Unified Patents) to capture anything not visible to open web search.

Caveats on this negative. I searched the ODP-derived block plus open web sources; paywalled PTAB/litigation databases were not fully rendered, so I cannot certify absolute absence — only that the canonical ODP list is empty and no public source contradicts it. I am not asserting that no IPR exists; I am asserting that the structured data shows none and my searches surfaced none. All claim numbers above (1–22) are quoted as they appear in the patent record; no per-claim PTAB outcome is stated because none exists.

One cross-reference correction to the earlier sections: the prior "Patent summary" flagged the abstract as unverified. That flag can now be closed — the record supplied the abstract verbatim (beam split into two paths, one to silver-salt film, one to a CCD, with an aperture diaphragm in the CCD path and the taking-lens diaphragm, the two diaphragms "correlatively controlled by a controller"). None of that changes the PTAB finding.

I'll reconstruct the assignment chain for US 5,664,243. Let me search the USPTO assignment records and cross-reference corporate-history sources.

Let me dig for the specific recorded-assignment reel/frame data and any post-Minolta transfers.

I hit the search-step limit before I could render the Assignment Center's reel/frame fields directly. Below is what the available records support, with explicit flags on the gaps rather than invented reel/frame numbers.

US 5,664,243 — Ownership / Assignment Reconstruction

Scope note. The governing fetched record is the Google Patents "Legal Events" chain for US5664243A, plus corroborating corporate-history sources (Konica Minolta annual reports and the 2006 Sony asset-transfer press release). I could not open the USPTO Assignment Center (assignmentcenter.uspto.gov) result set for this patent within the search budget, so I do not have reel/frame numbers, correspondent names, or execution dates beyond what the Google Patents reassignment entry states. I am flagging that gap rather than filling it.

Inventors

Nine named inventors, all on the 1996-06-06 US filing (priority JP 1995-06-08):

Basis for the employer call: every inventor on the Google Patents reassignment entry conveys to "MINOLTA CO., LTD," and third-party inventor profiles (patentleaderboard) attribute these individuals to Minolta / Minolta Co. with Japanese addresses (e.g., Seigenji — Sakai, JP; Honda — Hachioji, JP; Ohmori — Sakai, JP). This is a same-employer, single-assignee filing, which is the ordinary corporate pattern.

Unusual-pattern check — NOT present. There is no evidence of the "all inventors depart within 12 months of filing" precursor to a portfolio fire-sale. To the contrary, the inventor roster shows continuity: several of these names keep appearing on Minolta-family grants after this 1997 issuance — e.g., Seigenji on US 5,815,748 (1998-09-29); Honda on US 5,701,518 (1997-12-23) and, on the Konica Minolta side, on Konica Minolta Photo Imaging / Konica Minolta Opto grants. Ohmori's profile shows grants spread across Minolta, Minolta Co., Konica Minolta, and Konica Minolta Opto. That is the signature of retained R&D staff, not a departing-inventor cluster.

Original assignee

Minolta Co., Ltd. (also rendered "Minolta Camera KK" in the German counterpart DE 19622802 A1 and "Minolta Co., Ltd." on the US face).

• Product embodying the claims? Not confirmed. The specification (FIGS. 1–10) describes a body + swing-out grip + detachable/rotatable color-LCD electronic viewfinder + magnetic-tape deck — i.e., a hybrid film-SLR/EVF camera. The specification never names a commercial model, and I could not tie the disclosure to a shipped Minolta model with confidence. Treat "shipped a product embodying the claims" as unverified.
• Primary line of business at filing: consumer photographic cameras, lenses, copiers/office imaging, radiometric and optical instruments (per the Brazilian competition-authority filing describing Minolta Co., Ltd. at the 2003 merger: copiers, printers, cameras, optical units, radiometric and planetarium instruments).
• Current status: No longer an independent operating entity. Minolta Co., Ltd. merged with Konica Corporation via share exchange in August 2003, forming Konica Minolta Holdings, Inc., with Minolta becoming a subsidiary; Konica Minolta then exited the photographic film and camera businesses (camera business ended 2006-03-31; photo business ended 2007-09). The current operating successor is Konica Minolta, Inc. (info-equipment/optics). No Chapter 7/11 bankruptcy.

Contradiction flag (per your cross-reference rule): the earlier Patent-summary table lists "Assignee (original & current): Minolta Co., Ltd." That is accurate only as "the last entity named on a recorded assignment." It does not mean Minolta Co., Ltd. is the beneficial owner today — post-2003 ownership passes by corporate succession to Konica Minolta (and, for certain photographic assets, to Sony under the 2006 deal), which is normally not re-recorded per patent at the USPTO for a Japanese share-exchange merger.

Assignment timeline

Chronological, from the record actually available:

• Executed 1996 (on/around the 1996-06-06 filing) / recorded 1996-08-06 — Reel NOT RETRIEVED
  • Conveyance: Assignment of Assignors' Interest (Google Patents code: "ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS)")
  • Assignor: the nine inventors — Seigenji, Kiyoshi; Nagata, Hideki; Kato, Takashi; Hamamura, Toshihiro; Ohmori, Shigeto; Okada, Takashi; Honda, Tsutomu; Kubo, Hiroaki; Teramoto, Tougo
  • Assignee: Minolta Co., Ltd.
  • Correspondent: not available in the fetched record — I will not invent an attorney name. This is the field you specifically wanted; it must be read off the Assignment Center hit.
  • Context: Ordinary initial employment/obligation assignment from inventors to their employer, recorded ~2 months after filing (standard pre-issuance recording).

Post-issuance assignments: none found. The Google Patents "Legal Events" list shows, after the 1996-08-06 reassignment, only family/priority links — 1997-04-14 priority to US 08/834,107 (→ US 5,953,546) and 2003 priority to US 10/680,340 (→ US 7,133,608) — and the 2016-06-06 anticipated expiration. Priorities are not assignments. No second assignment, security interest, merger, or change-of-name record appears for US 5,664,243.

Corporate events that are not per-patent USPTO assignments but govern real ownership:

• 2003-08 — Konica/Minolta share exchange → Konica Minolta Holdings (succession, no per-patent recording shown).
• 2006-01-19 / effective 2006-03-31 — Konica Minolta PI transfers "certain assets" relating to α-mount DSLRs to Sony; Konica Minolta exits cameras. The scope was partial (development/design/production assets for α-mount DSLRs), and contemporaneous commentary noted KM retained much of its patent estate. Whether US 5,664,243 specifically was in that partial package is not determinable from the sources I could reach.
• Konica Minolta's FY2008 annual report states it was actively "identifying uses for patents from the defunct Photo Imaging business… transferring such patent assets to Group companies and third parties or hav[ing] licensed them." That is a general statement about the photo-imaging portfolio; it does not name this patent.

Bottom line for this section: the Assignment Center almost certainly has exactly one record for this patent (the 1996 inventors→Minolta assignment). If that is all it returns, that is itself the finding: no recorded transfer to any NPE; the patent has never been assigned to a licensing-only entity.

Timeline diagram

timeline
    title Ownership of US 5664243
    1995 : Priority filing in Japan
    1996 : US application filed
         : Inventors assign to Minolta Co Ltd
    1997 : Patent granted September 2
    2003 : Minolta merges into Konica Minolta
    2006 : Camera business ends March 31
         : Some DSLR assets go to Sony
    2016 : Patent expires June 6

NPE / troll-pattern signals

1. Shell-entity transfer — NOT PRESENT. The only recorded assignee is Minolta Co., Ltd., an operating camera/office-imaging manufacturer with a global product line. No LLC, no "IP/Holdings/Ventures" transferee, no registered-agent address appears anywhere in the chain (Google Patents reassignment entry, recorded 1996-08-06).

2. Known asserter in the chain — NOT PRESENT. No assignee in the chain matches any public NPE list (Acacia, Marathon, IV, Wi-LAN/Conversant, Vringo, Pendrell, Round Rock, Spangenberg entities, etc.). The chain is Minolta → (Konica Minolta by succession). No asserter-directory hit was found for this patent.

3. Repeat correspondent across the chain — UNCLEAR (data not retrievable). I could not obtain the correspondent-of-record for the 1996-08-06 assignment, and with only a single link in the chain the "recurrence" test cannot be run anyway. No finding. Flagged as the key field to pull from the Assignment Center hit.

4. Cascading transfers — NOT PRESENT. There is a single recorded transfer (1996). No chained LLC hop, and certainly none within 24 months.

5. Pre-litigation transfer — NOT PRESENT. No infringement suit naming this patent exists (per the companion litigation analysis), so there is no "assignment within 6 months before suit" to identify. No transfer at all post-1996.

6. Bankruptcy fire-sale — NOT PRESENT. Minolta did not file Chapter 7/11; it merged with Konica in 2003 and later wound down the camera/photo lines in an orderly exit. No bankruptcy-court patent sale is associated with this patent. (Minolta's ~$128M Honeywell autofocus settlement in 1992 is a liability event, not an asset fire-sale.)

7. Privateering — NOT PRESENT (and worth stating precisely). The 2006 Konica Minolta → Sony transfer was an asset sale to a large operating competitor/product-maker for Sony to build α-mount DSLRs — the inverse of privateering (operating co → NPE asserting on its behalf). No SEC-filed privateering arrangement involving this patent was found. Because I could not confirm this specific patent was even in the Sony package, I mark this not present rather than "unclear" — the named known privateering pattern does not appear.

8. Defensive aggregator — NOT PRESENT. The chain does not terminate at RPX, AST, LOT, Unified Patents, or OIN.

Verdict

Insufficient data (no records beyond the original assignment).

The chain for US 5,664,243 consists of exactly one recorded assignment — the 1996-08-06 inventors-to-Minolta Co., Ltd. conveyance of interest — with no subsequent recorded assignment, security interest, merger record, or change of name, and zero NPE signals (no shell LLC, no known asserter, no cascading transfers, no pre-suit transfer, no bankruptcy sale, no defensive-aggregator endpoint). Real-world ownership after 1996 moved by corporate succession (Minolta → Konica Minolta in the August 2003 share exchange, and possibly some photo-imaging assets to Sony effective 2006-03-31), but that happens by operation of law and is not reflected in this patent's USPTO assignment record — so the honest verdict is "insufficient data," with a strong negative finding on NPE/troll patterns.

Verification: search patent number 5,664,243 at the USPTO Assignment Center — https://assignmentcenter.uspto.gov/ (mirror: https://assignment.uspto.gov/patent/index.html) — to read off the reel/frame and correspondent for the 1996-08-06 entry, which are the two fields I could not retrieve here, and to confirm the absence of any post-1996 record.

Explicit gaps (not fabricated)

• Reel/frame for the 1996 assignment — not available in the fetched record.
• Correspondent of record (attorney/firm) — not available.
• Whether US 5,664,243 specifically was among the 2006 assets transferred to Sony — undetermined; the public releases describe only "certain assets relating to α-mount DSLRs."

I'll research the prior-art citations for US 5,664,243. Let me run several targeted searches.

Let me pull the actual "References Cited" section for US5664243 from multiple sources.

I now have the front-page "References Cited" list. Let me research each cited reference individually.

Prior-Art Analysis — US 5,664,243 ("Camera," Minolta Co., Ltd.)

0. Identification and scope

I confirm the target is US 5,664,243, application 08/659,690, filed 1996-06-06, priority 1995-06-08 (JP 7-142049 and 13 further JP filings), granted 1997-09-02, assignee Minolta Co., Ltd. I did not substitute any similar number (e.g., the Gore "'566" patent, the 3M/Walbro "'424" patents, or JP 特許5664243 (polyamide resin) — all distinct identifiers, as flagged in the earlier sections).

The patent's citation list was recovered from the front-page reproduction of the grant (uspto.report/patent/grant/5664243), cross-checked against the authoritative record at patents.google.com/patent/US5664243A/en.

Important honesty flag up front: I retrieved the complete front-page citation list and dates, but my ability to pull each cited document's own title, filing date, and disclosure was cut off (tool-step limit) before I could verify them individually. Accordingly, the "brief description" and §102 mappings below are given only where I can ground them; where I could not, I say so explicitly rather than invent content. Items marked [VERIFY] need a USPTO Patent Public Search / PATENTSCOPE full-text pull before being relied on.

1. The governing §102 framework (this matters for which citations even count)

US 5,664,243 was filed in 1996, so pre-AIA 35 U.S.C. §102 applies (the AIA first-inventor-to-file provisions apply only to applications filed on/after 2013-03-16).

• §102(b) — printed publications/patents dated more than one year before the 1996-06-06 U.S. filing, i.e., before 1995-06-06. This is the firmest category.
• §102(a) — art known/patented/published before the applicant's invention date.
• §102(e) — a U.S. patent that issued to another and was filed before the applicant's invention date, even if it issued after the applicant's filing date. This is the critical category here: five of the six U.S. references issued in Oct. 1995 – Dec. 1996, i.e., at or after the applicant's June 1995 priority date, so they can only operate as §102(e) art on the strength of their own earlier effective U.S. filing dates. [VERIFY each filing date — this is the single most important verification step.]

Because §102(e) references are effective only as of their filing dates, none of the five late-1995/1996 references can be assumed to disclose the applicant's specific correlative-dual-diaphragm contribution merely because it appears on the face of the patent.

2. The complete front-page "References Cited" list (verbatim from the grant)

U.S. Patent Documents

Foreign Patent Documents

Other References (non-patent literature)

1. "Nikon Digital Still Camera E2," Photographic Industries, Dec. 1994, vol. 52, No. 12, pp. 13–15.
2. "Zenza-Bronica Camphoto VX3000," Photographic Industries, Jun. 1994, vol. 52, No. 6, pp. 12–15.

Examiner of record: W. B. Perkey. Attorney: Burns, Doane, Swecker & Mathis. Field of search: 396/250, 246, 259, 260, 257, 287, 296, 374, 429; 348/296, 297, 333, 334, 64, 340, 363 — confirming the examiner searched hybrid film/TV-camera and beam-splitter art.

3. Reference-by-reference analysis

3.1 JP S63-284527 (Japanese Laid-Open) — Nov. 1988

• Full citation: Japanese Laid-Open Patent Application No. S63-284527 (Shōwa 63 = 1988), published Nov. 1988. [VERIFY assignee/applicant and exact publication day.]
• Publication type/date: Foreign printed publication / laid-open application, Nov. 1988 → squarely §102(b) art (well over one year pre-dating the 1996 filing).
• Brief description: This is the one cited reference whose subject matter is verified directly from US 5,664,243 itself. The specification states: "Japanese Laid-Open Patent No. S63-284527 discloses a camera which takes a photograph on a silver salt film and picks up an image on an image pickup device, and in which an image thus taken by the image pickup device can be reproduced and observed through a viewfinder." The spec further concedes that in such a camera "it is possible to preview an image frame taken on a silver salt film by displaying a stationary image in an electronic viewfinder," but that it "does not allow previewing of picture effects achieved by changes in aperture or shutter speed."
• §102 relevance: This is the closest prior art of record and the applicant's own admitted starting point for claims 17–22. It discloses the generic split-beam film + CCD + EVF-preview architecture. It is not, on the applicant's own characterization, anticipatory of any independent claim, because it lacks (i) a second aperture diaphragm in the image-pickup path (claims 1, 9, 17) and (ii) the correlative control / charge-accumulation preview recited in claims 1, 9, 17 and 20. Its natural role is as the §103 base reference for claims 17–22, not as a §102 anticipation.

3.2 JP H3-271730 (Japanese Laid-Open) — Dec. 1991

• Full citation: Japanese Laid-Open Patent Application No. H3-271730 (Heisei 3 = 1991), published Dec. 1991. [VERIFY applicant and subject matter.]
• Publication date: Dec. 1991 → §102(b) art.
• Brief description: [NOT VERIFIED — I did not retrieve the disclosure.] Based solely on its selection by the examiner alongside S63-284527 in the camera/beam-splitter field, it is presumably directed to camera light-amount or image-splitting art, but I will not assert its content.
• §102 relevance: [CANNOT ASSESS] without the disclosure. Flag for full-text pull; if it discloses a second diaphragm in a secondary light path (e.g., for photometry or a subsidiary image), it would be the most directly relevant §102 reference to claim 1.

3.3 US 4,855,837 — Tanimoto — Aug. 1989

• Full citation: US 4,855,837, inventor Tanimoto, issued Aug. 1989. [VERIFY exact title, assignee, filing date.]
• Filing/publication date: Issued 1989 → before 1995-06-06, so §102(a)/(b) art available.
• Brief description: [NOT VERIFIED.]
• §102 relevance: [CANNOT ASSESS] on the present record. It is the oldest reference and therefore the only pre-priority U.S. patent on the list; it is worth prioritizing for full-text review, because pre-priority U.S. patents are the only ones here that are not dependent on §102(e) date proof.

3.4 US 5,459,511 — Uehara et al. — Oct. 1995

• Full citation: US 5,459,511, Uehara et al., issued Oct. 1995. [VERIFY title, assignee, filing date.]
• Date issue: Issued after the 1995-06-08 priority date → usable only as §102(e) art if filed before the applicant's invention date. [VERIFY filing date — dispositive.]
• Brief description: [NOT VERIFIED.]
• §102 relevance: [CANNOT ASSESS.]

3.5 US 5,486,893 — Takagi — Jan. 1996

• Full citation: US 5,486,893, Takagi, issued Jan. 1996. [VERIFY title, assignee, filing date.]
• Date issue: Post-priority → §102(e) only. [VERIFY filing date.]
• Brief description: [NOT VERIFIED.]
• §102 relevance: [CANNOT ASSESS.] Note that "Takagi" also appears on the face of the patent as a §102(e)-type reference in analogous Minolta/Nikon camera art; do not conflate with other Takagi patents.

3.6 US 5,557,358 — Mukai et al. — Sep. 1996

• Full citation: US 5,557,358, Mukai et al., issued Sep. 1996. [VERIFY title, assignee, filing date.]
• Date issue: Issued after the 1996-06-06 U.S. filing date → §102(e) only, and only if its U.S. filing date precedes the applicant's invention date. [VERIFY filing date.]
• Brief description: [NOT VERIFIED.]
• §102 relevance: [CANNOT ASSESS.]

3.7 US 5,587,766 — Kawamura et al. — Dec. 1996

• Full citation: US 5,587,766, Kawamura et al., issued Dec. 1996. [VERIFY title, assignee, filing date.]
• Date issue: Post-filing → §102(e) only. [VERIFY filing date.]
• Brief description: [NOT VERIFIED.]
• §102 relevance: [CANNOT ASSESS.]

3.8 US 5,589,880 — Tsukui — Dec. 1996

• Full citation: US 5,589,880, Tsukui, issued Dec. 1996. [VERIFY title, assignee, filing date.]
• Date issue: Post-filing → §102(e) only. [VERIFY filing date.]
• Brief description: [NOT VERIFIED.]
• §102 relevance: [CANNOT ASSESS.]

3.9 Non-Patent Literature (both are §102(b) printed publications)

(a) "Zenza-Bronica Camphoto VX3000," Photographic Industries, vol. 52, No. 6, June 1994, pp. 12–15.

• Publication date: June 1994 → §102(b) (more than one year before the 1996-06-06 filing).
• Brief description (verified via the specification): This is the "conventional example" the patent itself describes: "an article in the June, 1994 issue of the 'Photographic Industries' magazine, pages 12 to 15, describes a camera which is capable of changing the path of an incident light beam for the purpose of photographing and observing an image at the same time… one of the divided light beam … taking a photograph on a silver salt or a silver halide film, and the other for picking up an image on a CCD… The CCD reportedly is of a 1/2-inch type."
• §102 relevance: This is arguably the most relevant single item of art of record — it is (i) §102(b) printed-publication art, (ii) the applicant's own admitted starting point, and (iii) the reference that establishes the problem the patent solves (the a/β light-loss problem for the small CCD, and hence the second-diaphragm design). As an anticipation reference it cannot reach the independent claims, because it does not disclose a second aperture diaphragm, correlative dual-diaphragm control, or the preview-by-second-diaphragm / charge-accumulation features of claims 1, 9, 17 and 20. It is, however, the strongest §103 base reference for claim 1.

(b) "Nikon Digital Still Camera E2," Photographic Industries, vol. 52, No. 12, Dec. 1994, pp. 13–15.

• Publication date: Dec. 1994 → §102(b) (more than one year before the 1996-06-06 filing).
• Brief description: [Content VERIFY] — a product-review article on the Nikon E2 digital still camera; the patent does not discuss it in the specification, which suggests it was a general-background citation by the examiner rather than applicant-admitted art.
• §102 relevance: [CANNOT ASSESS from record]; likely background on contemporaneous reduction-optics digital SLR design. Flag for review.

4. Bottom-line §102 mapping (preliminary)

Most relevant prior art, in order: (1) Zenza-Bronica Camphoto VX3000 article (June 1994, §102(b)) and (2) JP S63-284527 (Nov. 1988, §102(b)) — both §102(b) art and both expressly discussed in the specification as the admitted prior art; then (3) JP H3-271730 (Dec. 1991) and (4) US 4,855,837 (Tanimoto, 1989), the only other references not dependent on §102(e) date proof; then (5) the five §102(e)-only U.S. references (Uehara, Takagi, Mukai, Kawamura, Tsukui), each contingent on its filing date.

5. Explicit caveats and what should be done next

1. Verification gap (material): I obtained the complete citation list and its dates from the grant's front page, but could not verify the title, assignee, filing date, or disclosure of US 4,855,837, US 5,459,511, US 5,486,893, US 5,557,358, US 5,587,766, US 5,589,880, JP H3-271730, or the Nikon E2 article before the tool limit. I have not fabricated descriptions for them, and I flag that the requested "brief description / anticipatory claim" fields are incomplete and must not be relied on for those eight entries.
2. The §102(e) dates control. For the five U.S. references issuing between Oct. 1995 and Dec. 1996, the entire §102 analysis turns on whether each was filed before the applicant's invention date (no later than 1995-06-08). Pull the filing dates (and any pre-1995 priority) from USPTO Patent Public Search / PATENTSCOPE before treating any of them as prior art.
3. Family members are not prior art. US 5,953,546 (Okada et al., 1999-09-14; continuation from 08/834,107) and US 7,133,608 (from 10/680,340) are same-family documents and must not be counted as §102 art against US 5,664,243. Likewise the 13 JP priority filings (JPH095865, JPH08334829, etc.) are the priority basis, not art.
4. Forward citations are not prior art. US 5,664,243A appears in the "Patent Citations" tables of later patents (e.g., US 8,818,184; US 2003/0117508; US 8,125,537; and Russian RU2612363C2), and JP 2-87129 (Minolta) is cited as "X" art in the search report of the unrelated WO2015/025878 — none of these are prior art to US 5,664,243; they are citations of it.
5. Recommended next step: run each of the eight unverified identifiers through USPTO Patent Public Search (full-text) and PATENTSCOPE, capture the filing dates and independent-claim-level disclosures, and then re-run the §102 mapping in §4 above. The two §102(b) printed publications (Zenza-Bronica VX3000, June 1994; Nikon E2, Dec. 1994) and JP S63-284527 should also be pulled in original form to confirm the specification's characterization before any validity position is taken.

I'll ground this § 103 analysis in the prior art actually identified on the record. Let me first try to recover the patent's cited-references list, since the fetched specification only names the background references.

Let me verify the EP counterpart's search report and whether US 5,664,243 has a front-page citation list I can use.

Obviousness Analysis — U.S. Pat. No. 5,664,243 ("Camera," Minolta)

0. Scope, premises, and inherited flags

This analysis builds on the earlier sections (bibliographic data, claim overview, litigation check) and does not repeat them. Two inherited caveats materially constrain what can be analyzed:

• The verbatim text of claim 1's preamble and of dependent claims 2–8 is not available on the record I fetched. I analyze claims 1, 9, 17, and 20 (the independents) against their near-verbatim/paraphrased text already summarized, and claims 10–16 and 18–22 as characterized. Claims 2–8 are analyzed only generically (as dependent add-ons in the same families as 10–16 / 18–22) and are expressly flagged below.
• The prior-art cutoff is the 1995-06-08 priority date (pre-AIA § 103 applies; the AIA's "preponderance / obvious-to-try" framing in KSR still governs the substantive analysis).

The task directs me to use the "Prior Art" section of the record. That section of the Google Patents page for US5664243A consists of (i) algorithmically generated prior-art keywords — aperture, camera, mode, aperture value, shooting — and (ii) the specification's own "Description of the Prior Art," which names three references. Those three, plus the applicant's own admitted problem statements, are the only prior art I can ground with confidence. I flag externally surfaced references separately in § 10.

1. Legal framework

• Graham v. John Deere Co., 383 U.S. 1 (1966): scope/content of the prior art; differences; PHOSITA level; secondary considerations.
• KSR Int'l Co. v. Teleflex Inc., 550 U.S. 398 (2007): the TSM test is not the sole route to obviousness; a combination is obvious where it does no more than yield predictable results, where there is a design incentive/market pressure, where a known technique is used to improve a similar device in the same way, or where the solution is one of a finite number of identified, predictable options ("obvious to try").
• In re Fritch, 972 F.2d 1260 (Fed. Cir. 1992) and Southwall Techs., Inc. v. Cardinal IG Co., 54 F.3d 1570 (Fed. Cir. 1995): the applicant's own admissions in the specification about the prior art and the problem to be solved are usable as prior art. This is central here, because the specification expressly concedes the problem and even points toward its solution.

2. The prior art of record

Grounded sources: the specification text at https://www.sumobrain.com/patents/us/Camera/5664243.html, https://patents.google.com/patent/US5664243A/en, the identical background reproduced in the continuation https://patentimages.storage.googleapis.com/c2/28/d5/f3b48c541b126d/US5953546.pdf, and JP S63-284527's own record at https://patents.google.com/patent/JPS63284527A/.

PA-2 corroboration (independent check): the JPS63284527A record confirms its subject matter is exactly a silver-halide camera with an electronic viewfinder that performs "擬似撮影" (pseudo/simulated shooting) — displaying a still image in the image-pickup device's electronic viewfinder to let the photographer confirm composition before committing film. This is consistent with the specification's characterization. It also confirms PA-2 concerns only still-frame confirmation, not live aperture/shutter-effect preview.

3. The specification's own admissions (usable prior art under Fritch/Southwall)

The spec is unusually generous to an obviousness challenger. It admits:

1. The reduction-relay requirement is a known necessity. "[E]ven the image area of a comparatively large image pickup device of a 1-inch type… is substantially smaller than a image area on a film. Accordingly… it is necessary to use a reduction optical system such as a relay optical system… the relay optical system needs to have a magnification of 1/30 to 1/8." This is the applicant conceding that a relay optical system in the pickup branch is standard art.
2. The problem to be solved is expressly stated, and the solution direction is hinted. "although the exposure of a silver salt film can be adjusted by adjustment of aperture, the exposure of a image pickup device cannot be adjusted in the same manner; a different adjustment needs to be devised." That sentence is essentially a motivation statement for an independent light-control element in the pickup branch — i.e., the second aperture diaphragm of claim 1 / the ND filter of claims 19 and 22.
3. The decoupling problem is expressly stated. "if the aperture of the taking lens is adjusted to be narrower than F=5.6… the amount of light incident on the image pickup device is also affected, disturbing proper picking up of an image."
4. The known preview mechanism's defects are admitted (dark image; AF defeated; no still frame; no shutter-speed preview).

4. Person having ordinary skill in the art (PHOSITA)

A camera-design engineer (as of June 1995) with a working knowledge of: SLR optics (taking-lens aperture diaphragms, DOF/preview mechanisms, AF/phase-detection light paths), beam-splitting optics and relay/reduction systems, CCD imaging (charge-accumulation/electronic-shutter exposure control), and camera control firmware. This is the ordinary artisan of the Minolta hybrid-camera field — not a specialist in any one sub-discipline.

5. Claim-by-claim obviousness

Claim 1 — split beam; first diaphragm; second diaphragm in the pickup path; controller drives both correlatively

Proposed rejection: PA-1 in view of PA-3, further in view of the applicant's admitted problem (§3.2–3.3).

Motivation (KSR): (a) The film and the CCD have different sensitivities and the beam-splitter delivers a fixed fraction to each; the taking-lens aperture cannot independently expose the CCD over the whole range (admitted). (b) The specification itself says "a different adjustment needs to be devised," and PA-3 supplies the only known light-control element (an aperture diaphragm). (c) Placing an aperture stop in a relay/pickup optical path is the known technique for controlling light throughput in that branch. This is the prototypical KSR case — "combination of familiar elements according to known methods… yield[ing] predictable results."

Strength of rejection: strong for the claim's scope as summarized. The word "correlatively" is broad and is met by any coordinated control law (including the spec's own a/β scheme).

Claims 2–8 — ⚠️ NOT ANALYZABLE

The text of these dependents is not on the record I fetched (flagged in the inherited summary). On the assumption they are structural/control refinements analogous to 10–16 and 18–22 (e.g., relay-system details, filter placement, sensor readout), the same PA-1 + PA-3 + admitted problem combination would likely dispose of most of them. I decline to assert a per-claim conclusion without their text. This is a gap to close by pulling the USPTO full-text image.

Claim 9 — adds a relay optical system in the pickup branch and the second diaphragm inside it

Proposed rejection: PA-1 + admitted necessity of a reduction relay (§3.1) + PA-3.

The applicant concedes the relay is required (CCD area ≪ film area; 1/4–1/2-inch CCDs; β ≈ 1/30–1/8, practically 1/3 in the worked example). Once the relay is conceded and an independent pickup-branch stop is motivated (§3.2), locating that stop at the relay's pupil is the standard, predictable place for an aperture in a relay system. This is KSR's "known technique to improve a similar device in the same way."

Strength: strong.

Claims 10–16 — dependents (control limits; 13/15 recite b/β and b; 16 recites the second diaphragm being able to fully close)

• Claim 16 (full closure / beam interrupt): A diaphragm that can close completely is the ordinary end-trip of a known element; using it to blank the pickup branch (e.g., during film-only exposure, to prevent CCD saturation/smear) is a predictable use. Strong.
• Claims 13/15 (b/β, b): These express the inherent consequence of a reduction relay of magnification β with an open aperture b — the taking-lens aperture beyond b/β cannot influence the CCD. A numeric limit that is the result of known variables and is result-effective is obvious under In re Aller, 220 F.2d 454 (CCPA 1955) and In re Boesch, 617 F.2d 272 (CCPA 1980). The applicant's own FIG. 14 discussion derives a/β = 5.6 as a physical fact, not an invention. Strong–moderate (a patentee can argue the recognition was a discovery, but the value is dictated by the optics).
• Claims 10–12, 14: control refinements within the ordinary skill of a camera-control designer. Strong, pending their text.

Claim 17 — setting device for the first diaphragm's aperture; second diaphragm in the pickup path; controller drives the first diaphragm per the setting during film imaging, and drives the second diaphragm per the setting when film imaging is not performed, so the EVF shows the image

Proposed rejection: PA-2 in view of PA-3, further in view of PA-1 and the admitted defects of PA-3 (§3.4).

Motivation (KSR) — this is the strongest motivational showing in the patent:

• PA-3 teaches the desire to preview aperture effects (DOF) but is admittedly defective ("the image… is dark… does not offer a clear image when the aperture is extremely stopped down"), and also defeats AF.
• PA-2 teaches that the hybrid camera has an EVF whose very purpose is to display a preview image.
• The two references are in the same field and solve the same problem (how to let a photographer see the effect of settings before exposure). A PHOSITA, facing the admitted dark-preview defect, would relocate the preview to the pickup/EVF branch — i.e., drive a pickup-branch stop to simulate the taking aperture while leaving the taking/optical path bright. That is precisely the claimed allocation.
• KSR: (i) "simple substitution of one known element for another"; (ii) "known technique to improve a similar device in the same way"; and (iii) "obvious to try" — with the pretest that the number of options (put the preview stop in the taking branch vs. the pickup branch) is small and the outcome predictable.

Strength: strong, but this is the claim a patentee would most credibly defend (see §8).

Claims 18–19 — sensor charge-accumulation time synchronized with the second-diaphragm operation (18); variable-density (ND) filter in the pickup path (19)

• Claim 18: Synchronizing CCD integration time with a live aperture change is the standard electronic-shutter/exposure-loop technique of every 1990s video camera; it is required to keep EVF brightness constant as the stop moves. Strong (KSR "known technique… same way").
• Claim 19: Neutral-density filters for light attenuation in an image path are ubiquitous; the spec itself uses an ND filter (C13) in the very same branch. Substituting an ND filter for, or adding it to, the second diaphragm is a predictable alternative light-control element — and KSR expressly allows for "a finite number of identified, predictable solutions." Strong.

Claim 20 — setting device for the shutter speed; controller drives the shutter per the setting during film imaging, and controls the image pickup's charge-accumulation time when film imaging is not performed, so the EVF displays the image

Proposed rejection: PA-2 + PA-3 + the well-known video-camera electronic-shutter technique (and the spec's own admission that the conventional preview "does not allow observation of… picture effects (such as a shaken-image effect) achieved by a change in shutter speed").

Motivation (KSR): Every frame-capture device's motion blur is a function of its exposure duration. A film SLR's shutter speed and a CCD's charge-accumulation time are known functional equivalents for that purpose — the specification itself calls the CCD accumulation time "shutter speed (electric charge accumulation time)" throughout. Once PA-2 puts an EVF on the camera and PA-3 establishes that photographers want to preview shutter effects, setting the CCD's accumulation time to the set shutter speed to reproduce the same motion blur in the EVF is a predictable use of a known technique (electronic shutter control) to improve a similar device in the same way. The claim requires no more than that.

Strength: strong.

Claims 21–22 — second diaphragm operated in synchronization with accumulation control (21); ND filter in the pickup path (22)

Same rationale as claim 18 and claim 19, respectively. Strong.

6. Consolidated combination table

Overarching motivation to combine PA-1, PA-2, PA-3 (all in the same field, all addressing hybrid film/electronic viewing): all three are directed to the same problem — taking a silver-halide photograph while electronically observing/pickup-ing the image — and PA-3 supplies the artist's known answer to "let me see the effect of my settings before I commit." The hybrid camera of PA-1/PA-2 is the natural host for PA-3's preview function, and the EVF is the natural output. KSR at 417 ("if a technique has been used to improve one device, and a person of ordinary skill… would recognize that it would improve similar devices in the same way, using the technique is obvious").

7. Secondary considerations (objective indicia)

There is no evidence on this record of: unexpected results, commercial success (the spec never names a product model — flagged in the inherited summary), copying, industry praise, licensing, or a nexus to any product. The only "objective" fact in the record points toward obviousness rather than away: the specification's own framing establishes that the problem (dark, AF-defeating preview of aperture/shutter effects) was recognized in the art, and that a known class of solution (aperture/light control in the imaging path) existed. A recognized problem plus an available solution class is a motivation, not a non-obviousness shield.

A patentee could try to convert the admitted "long-felt need" (SLR preview is dark; no way to preview shutter effects) into objective evidence of nonobviousness, but that evidence cuts against them unless they can also show that the claimed allocation (drive the pickup-branch stop for preview, keep the taking branch open) was not the predictable answer. That is a factual question that would turn on the art and would need expert testimony — no record for it here.

8. Where a patentee could push back (residual non-obviousness arguments)

I am professionally obliged to state the counter-case rather than only the rejection:

1. Claim 1's "correlatively" is vague, but so is the obviousness case — vagueness is a § 112 vulnerability, not a § 103 defense.
2. Claims 13/15 (a/β): A patentee can argue the recognition that the taking-lens aperture beyond a/β is optically invisible to the CCD was a non-trivial discovery, citing the spec's FIG. 14 analysis. Counter: the value is a mathematical consequence of a reduction relay's open aperture and magnification (Aller/Boesch), and the spec derives it, not invents it.
3. Claim 17: The strongest defense. A patentee can argue PA-2's EVF is disclosed only for still-frame confirmation, and PA-3's preview is a mechanical stop-down of the taking lens; neither reference suggests dynamic, live aperture-effect preview generated in the pickup branch. The rebuttal to that is the applicant's own admission that PA-3's preview is defective precisely because it stops down the taking path — which is a reason to relocate preview to the other branch. Expect this claim to hinge on whether "relocating preview to the EVF branch" is treated as a predictable design choice (KSR) or an inventive insight.
4. Claims 2–8 cannot be argued either way until their text is recovered; a patentee could theoretically have narrowed them into a genuinely non-obvious pocket.

Teaching-away check: I found no teaching-away in the record. PA-3 does not disparage an independent pickup-branch stop; PA-2 does not teach away from live preview — it simply does not address it. Absence of a teaching-away strengthens the § 103 case under KSR.

9. Bottom line

Taking the record's own prior-art section at face value, U.S. 5,664,243's independent claims are, on the whole, more likely than not obvious under pre-AIA § 103:

• Claim 1 / claim 9 (dual-diaphragm, relay-located stop): obvious over PA-1 + PA-3 + the specification's own admitted problem ("a different adjustment needs to be devised" for CCD exposure).
• Claims 10–16 / 18–19 / 21–22 (dependents): obvious as ordinary design choices, standard video-camera integration-time control, ND-filter light attenuation, and result-effective numeric limits.
• Claim 17 (aperture-effect preview via the pickup-branch stop): the closest call, but still obvious over PA-2 + PA-3 + the admitted darkness/AF defects of the conventional preview mechanism.
• Claim 20 (shutter-effect preview via accumulation time): obvious over PA-2 + PA-3 + the known electronic-shutter technique, especially given the applicant's admission that the conventional mechanism "does not allow observation of… a shaken-image effect."

Note that this is a retrospective validity-style analysis: the patent expired 2016-06-06 (per the inherited bibliographic section; Expired – Lifetime), so no live § 103 challenge can now be brought. The analysis is therefore of historical/defensive value (e.g., freedom-to-operate on the now-public subject matter, or understanding the family's prosecution history).

10. Corroborating examiner-cited art found off-record — ⚠️ FLAGGED AS UNVERIFIED

While searching, I surfaced a European search report (https://patentimages.storage.googleapis.com/af/3d/c1/ee4c2a2605538d/EP0810778A3.pdf, application "EP 97 10 8812") citing, as "A" (background) art: JP 04-316282 A (Fuji Photo Film, 1992-11-06) & its family member US 5,589,889 A (Kamaka); US 4,394,688 A (Iida et al., 1983-07-19); JP 63-232682 A (Canon, 1988-09-28); and EP 0 708 433 A (Canon, 1996-04-24).

Important caveat: I could not confirm that EP 97 10 8812 / EP 0 810 778 is the European counterpart of US 5,664,243 — its classification (H04N5/202, H04N1/21) and the cited subject matter (image-memory/gamma-correction, e.g., Kamaka's US 5,589,889 is an image memory device, not a split-beam camera) are not a clean match, and I did not verify the applicant. I therefore do not rely on these references in the § 103 conclusions above; they are offered only as leads an examiner might have used, subject to verification against the actual EP/US564243 family link.

Similarly, a PCT search report for WO2015025878A1 cites JP 2-87129 A (Minolta Camera Co., 1990-03-28) as "X" art (family: none, & US 6,724,991 B1) against a camera claim set. That is a different application's search report and I have no verified content for JP 2-87129 A; I flag it as a candidate reference only, not as ground truth.

Confidence: High on the PA-1/PA-2/PA-3-based analysis (those references are verbatim on the record and all predate the 1995-06-08 priority date). Medium on the a/β numeric-range dependents (13/15) and on claim 17, which are the two places a patentee has a genuine argument. Low / not assessable on claims 2–8, whose text I could not recover.

If you want, the next step to remove the remaining flags is to pull claim 1's preamble and claims 2–8 verbatim from the USPTO Patent Public Search full-text (or the granted-PDF images at patentimages.storage.googleapis.com) and to verify whether EP 97 10 8812 is in fact the European family member.