Invalidity dossier
US 4991064
Silhouette lightpipe illumination for vehicle instrumentation
Current assignee: Delco Electronics LLC
Added 9/23/2026, 3:39:26 PM
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Patent summary
Title, assignee, inventors, filing/issue dates, abstract, and a plain-language overview of the claims.
Patent Overview: US 4,991,064 A
Title: Silhouette lightpipe illumination for vehicle instrumentation
Patent number / application: US 4,991,064 A (application US07/446,248)
Inventor: James M. Clem
Assignee: Delco Electronics Corporation (a corporation of Delaware); listed current assignee is Delco Electronics LLC.
Key dates: Filed 1989-12-05; priority 1989-12-05; granted/published 1991-02-05. Anticipated expiration 2009-12-05; status listed as "Expired – Fee Related." Related filings: EP0431667A1 and JPH03186715A.
Purpose: The invention illuminates both the display graphics and the pointer of a nonemissive vehicle instrument panel so they are viewable by the driver during low ambient lighting, while avoiding the heating, pointer shadowing, weight, cost, and packaging drawbacks of front-lighting, floodlighting, and pointer lightpiping. A single common lightpipe apparatus is positioned on the rear face of the display, so no separate pointer lighting is required.
Plain-language scope: A vehicle display (10) includes a rotary actuator (12), a lightpipe apparatus (14) with discrete lamps (15) and a light emissive region (16), an applique (18) bearing bright opaque graphic symbols (20), and a rotatable pointer (22). The applique—a multi-layered film with a translucent or neutral-density base film (e.g., 35% transmissivity polycarbonate)—has an opaque coating outside a translucent region (38) registered with the emissive region, and bright opaque symbols (white and/or orange) on its front face; symbols may also be placed on the rear face. The pointer is predominantly opaque and brightly colored, with a transparent region or opening along its stem, appearing as two like-colored stripes separated by a contrasting center stripe. In high ambient light with lamps unlit, the bright opaque symbols and pointer stripes are perceived against the relatively dark translucent region. In low ambient light with lamps lit, the symbols and outer pointer stripes appear in silhouette against the relatively bright translucent and transparent regions; light passes through the pointer's transparent stripe.
Source: https://patents.google.com/patent/US4991064/en
Not established by the excerpt: The full claims, the complete description, drawing details, exact materials beyond examples given, and any legal conclusions such as validity or claim scope. No litigation, ownership-transfer, or prior-art analysis is provided.
Generated 10/1/2026, 9:51:25 PM
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Litigation summary
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PTAB challenges
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Assignment history
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Prior art
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Derivative works
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