Invalidity dossier
US 5349503
Illuminated transparent display with microtextured back reflector
Current assignee: Nokia Bell Labs USA
Added 9/23/2026, 3:05:12 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 5,349,503 A
Title: Illuminated transparent display with microtextured back reflector
Patent number / application: US 5,349,503 A; application US 08/052,320
Inventors: Greg E. Blonder; Bertrand H. Johnson
Original assignee: AT&T Bell Laboratories Inc. Current assignee listed as Nokia Bell Labs USA / AT&T Inc.
Key dates: Priority date 1991-12-31 (claimed from US 07/816,405); filing date 1993-04-23; publication/grant date 1994-09-20; anticipated expiration 2011-12-31. Legal status: Expired – Fee Related. Related JP and EP filings are listed.
Purpose: The invention relates to illuminating devices, particularly for illuminating transparent displays such as liquid crystal displays (LCDs). It addresses low LCD contrast and the inefficiency of conventional backlighting, which is described as a major battery drain even in portable computers.
Plain-language scope: The disclosure describes a reflector with a base plane and a microtextured surface made of microelements having maximum lateral dimensions under 125 micrometers and smooth, continuous, mold-formed surfaces. A preferred surface uses closely packed spherical segments, e.g. about 25-micron diameters and 4-micron altitudes, optionally mixed with random segments. Applied to a transparent display, the reflector is formed on a major surface of a transparent substrate acting as a light guide (thickness roughly 0.5–1.0 mm), with a light source directing light into the substrate approximately parallel to that surface. Much of the light undergoes total internal reflection until it strikes a microelement and is reflected out, providing efficient illumination over an enhanced range of viewing angles. Figures cover reflector structure, a display cross-section, intensity versus viewing angle, fabrication steps, and low-light embodiments.
Source: https://patents.google.com/patent/US5349503/en
What the excerpt does not establish: It is a partial excerpt—the specification text and claims are truncated and omitted, so exact claim language, claim count, dependencies, and the full fabrication detail are not verifiable here. Dates, assignee listings, and legal status on the source page are expressly assumptions, not legal conclusions. No litigation, ownership-transfer, validity, or prior-art analysis is supplied or undertaken.
(Word count: ~300.)
Generated 10/1/2026, 9:51:48 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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Obviousness
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Extensions
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Derivative works
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