Invalidity dossier
US 4177501
Illuminated keyboard
Current assignee: Harris Corp
Added 9/23/2026, 1:22:33 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 4,177,501 A
Title: Illuminated keyboard
Inventor: James H. Karlin
Original/current assignee (per source): Harris Corp
Application no.: US05/851,694
Priority/filing date: 1977-11-15
Publication (grant) date: 1979-12-04
Legal status as listed: Expired – Lifetime (anticipated expiration 1997-11-15); the source states legal status is an assumption, not a legal conclusion.
Purpose. The invention concerns an improved illuminating arrangement for instrument panels and pushbuttons, such as those on calculators and telephones, using edge illumination of transparent plastics. It also covers improved pushbutton retention arrangements for illuminated arrays. The stated object is an illuminating arrangement using a light-diffusing sheet-type light-pipe that avoids reflective material or components placed within the direct light path.
Plain-language scope (from the supplied text). A light source (shown as a bulb) sits adjacent an edge of a light-pipe sheet, optionally in a recess in one end. Selected areas of the light-pipe's rear surface are roughened, e.g. by etching, to deflect light up through its front surface toward graphics and pushbuttons. A conventional disk-type calculator keyboard sits atop the light-pipe, with apertures (slots or holes) punched or routed around its disks. An optional die-cut foam pad with openings can reduce rattle. Pushbuttons with an upstanding key top and laterally extending flanges are held in square apertures of a frame-like cover; apertures in the flanges let light reach underlying graphics directly. The pushbuttons are retained by extension flanges at the aperture corners (described as forming roughly a 45° angle), engaging the top surface of the pushbutton-flange corners. A die-cut label, optionally adhesive-backed, overlays the cover and carries graphics formed as translucent or transparent areas; openings in the label receive the key tops. A further embodiment shows thicker flanges (10′) with a notch or recess (12).
Not established by the excerpt. The excerpt omits the full claims and much of the description, so the precise claim scope, any additional embodiments, and the full prior-art discussion are not established here. Classifications and cited prior-art patents are listed by the source but are not analyzed above.
Generated 10/1/2026, 9:53:09 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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