Invalidity dossier
US 4417792
Device for mounting diapositives in a strip and an apparatus for projecting the strip-mounted diapositives
Current assignee: SCHROD A OF WEST GERMANY GmbH LLC
Added 9/17/2026, 2:39:19 PM
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Patent summary
Title, assignee, inventors, filing/issue dates, abstract, and a plain-language overview of the claims.
Patent Overview — US 4,417,792 A
Title: Device for mounting diapositives in a strip and an apparatus for projecting the strip-mounted diapositives
Assignee/Inventor: Inventor listed as "geb. Boser Liesel Martin"; original assignee "Individual"; later reassigned to SCHROD GmbH (a West German limited liability company), recorded 1990-03-21. Google's listing shows a current assignee of "SCHROD A OF WEST GERMANY GmbH LLC," but the source itself cautions listed assignees may be inaccurate.
Key dates: Priority date 1980-06-04; filing date 1981-06-04; granted/publication date 1983-11-29; anticipated expiration 2001-06-04; legal status "Expired – Fee Related."
Purpose: To mount diapositives (slides) in a strip for successive projection in a slide projector, and to provide an apparatus for projecting such strip-mounted slides.
Plain-language scope (from the description):
- A pair of flexible sheet members (2, 3), each with at least two side-by-side picture openings (4, 5), fastened face-to-face but mutually offset by one picture-opening width.
- A frame/mask (6) with a picture opening (7) interposed between the sheet members, its opening aligned with those in the sheets and slightly larger than both the diapositive and the sheet openings; the frame is thicker than the diapositive.
- The diapositive (8) thus "floats" with clearance/play (9), held by the sheet members but free to move, reducing bending when the strip is coiled and distributing heat uniformly.
- Perforations (10, 11) along strip edges engage drive pinions; half-sheet covers terminate strip ends; cassettes, hook interconnection structures, a preview viewing window, and a double diaphragm are also described.
Source: https://patents.google.com/patent/US4417792/en
What the excerpt does not establish: Claims themselves are not included, so the exact patented scope cannot be stated. It does not establish prosecution history, claim interpretation, enforceability, or the full reference numerals/embodiments beyond those quoted (text is excerpted). No legal conclusions on validity, ownership transfers, or prior art are drawn.
Generated 10/1/2026, 10:03:04 PM
Cases on file (0)
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Litigation summary
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Proceedings on file (0)
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No PTAB proceedings on file. This patent has not been challenged via IPR, PGR, or CBM. The absence is itself a signal — well-asserted patents eventually attract IPRs. The LLM analysis below may surface filings the ODP feed hasn’t indexed yet.
PTAB challenges
AIA trial proceedings at the USPTO Patent Trial and Appeal Board — IPR, PGR, and CBM. Petitioners, judge panels, claim-level invalidation outcomes from Final Written Decisions, and Federal Circuit appeals. The single most important defensive datapoint after litigation history.
Assignment history
Inventors, original assignee, and the chain of ownership recorded with the USPTO — including the correspondent attorney who recorded each assignment, since shell-LLC chains often share one repeat-player attorney even when the entity names look unrelated. Surfaces NPE / patent-troll patterns: shell-entity transfers, known asserters in the chain, repeat correspondent fingerprints, pre-litigation assignments, and bankruptcy fire-sales.
Prior art
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Obviousness
Combinations of prior art that suggest the claimed invention would have been obvious under 35 U.S.C. § 103.
Extensions
Patent term adjustments, term extensions, continuations, divisionals, family members, and expiration dates.
Derivative works
Defensive disclosure: derivative variations of each claim designed to render future incremental improvements obvious or non-novel.