Invalidity dossier
US 4460940
Added 9/23/2026, 10:31:44 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 4,460,940 A
Title: Apparatus for uniform illumination employing light diffuser.
Assignee/Inventor: Inventor Kei Mori; original assignee listed as "Individual" (no corporate assignee shown).
Number/Application: US 4,460,940 A; application US06/438,427, filed 1982-11-02.
Dates: Priority 1981-11-07 (JP 56178887); additional priorities 1981-11-11 (JP 56180761) and 1981-11-27 (JP 56189999). Granted/published 1984-07-17. Status listed as expired–fee related; anticipated expiration 2002-11-02.
Purpose (plain language): Light traveling through a light guide (quartz glass fibers, plastic optical fibers such as acrylic or polycarbonate resin, or fine tubes/flat plates) must be routed out to illuminate things evenly — for example, meter dials in audio instruments and vehicles, where uniform intensity across the whole dial matters. The invention diffuses light out of the transmission element so a desired wavelength component can be steered to the outside, and provides an apparatus for uniform illumination.
Scope as described: A light diffusing device has discrete light diffusing layers spaced apart on a surface of the transmission element, each discharging to the outside only a light component of a specific wavelength. The layers are made of resin (e.g., silicon resin, epoxy resin) with refractive index n₁ differing from the element's n₀, where n₁/n₀ is preselected within about 0.87–1.3. Sections may be single-layer, double-layer (n₁, n₂), or triple-layer (n₁, n₂, n₃), selectively reflecting thermic rays (R) and intercepting ultraviolet rays (V). Optional reflecting layers sit opposite the diffusing sections or at the element's far end. Sections may be convex or concave lenses, singly or stacked; convex shapes may be formed by dropping resin and letting viscosity/surface tension/contact angle determine shape, concave by a procedure shown in FIG. 4. An apparatus includes a light source plus this transmission element.
Source: https://patents.google.com/patent/US4460940/en
Not established by this excerpt: The full text of the claims (claim language is not reproduced), dependent-claim specifics, the complete description, drawing contents, and any prosecution history. Numeric refractive-index examples beyond the stated range, and any limitations appearing only in the claims, are not verifiable here.
Generated 10/1/2026, 9:33:20 PM
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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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