Invalidity dossier
US 4183628
Electronic watch and display device for such watch
Current assignee: Ebauches SA
Added 9/23/2026, 3:18:26 PM
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Patent summary
Title, assignee, inventors, filing/issue dates, abstract, and a plain-language overview of the claims.
Patent Overview: US4183628A
Title: Electronic watch and display device for such watch
Patent Number: US4183628A
Assignee: Ebauches SA (original and current assignee, per listing)
Inventors: Claude Laesser, Rene Viennet, Eric Saurer
Priority Date: 1976-05-20 (claimed from CH633476A and CH633576A)
Filing Date: 1977-05-13
Publication/Grant Date: 1980-01-15
Status: Expired – Lifetime (anticipated expiration 1997-05-13)
Purpose: The patent addresses drawbacks in known electronic watches where photo-electric cells and passive display cells are juxtaposed on the watch face—an unaesthetic arrangement that also limits display size to about 3.5 digits. The invention places photo-electric cells behind the display cell, separated by a half-transparent (dielectric) mirror, so light above a chosen wavelength passes through to recharge the accumulator while shorter wavelengths are reflected for reading the display. A second embodiment covers a display device with a lighting device, using a diffuser and half-transparent mirror behind the cell so a light source permits night reading by transparency while the mirror reflects other wavelengths for day reading by reflection.
Plain-language scope: The patent describes an electronic watch with a rechargeable accumulator, photo-electric cells, and a passive electro-optic (liquid crystal) display. A dielectric mirror—built from thin dielectric coatings of materials such as ZnS, Na₃AlF₆, and PbTe—is positioned between the display and the photo-electric cells, selectively transmitting (for recharging) and reflecting (for display) different light wavelengths. Variants include frost glass diffusers and a laterally positioned light source for illumination.
Source: https://patents.google.com/patent/[US4183628](/patent/US4183628)/en
What the excerpt does not establish: The full text of claims, dependent claim scope, and the complete FIG. 5/6 lighting embodiments are omitted. The excerpt is incomplete; classification and legal-status items are noted as assumptions or non-legal conclusions. No litigation, ownership-transfer, validity, or prior-art analysis is provided here.
Generated 10/1/2026, 9:51:40 PM
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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.