Light guide
First Claim
Patent Images
1. A light guide for illuminating an information-bearing member, comprising:
- a transparent plate having at least one area associated with the information-bearing member, the plate having means for reflecting light from an external light source into the plane of the plate,wherein the reflecting means comprises first reflecting means for directing light from the light source in a first direction in the plane of the plate, second reflecting means for reflecting light from the first reflecting means in a second direction transverse to said first direction and in the plane of the plate, third reflecting means for reflecting light from the second reflecting means in a third direction transverse to the second direction and substantially parallel but in the opposite sense to the first direction and in the plane of the plate, and fourth reflecting means for reflecting light from the third reflecting means towards said first reflecting means in a fourth direction transverse to said first and third directions and substantially parallel but in the opposite sense to the second direction and in the plane of the plate.
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Abstract
A light guide for illuminating a keyboard or keypad from behind comprises a transparent grid-like plate having an array of apertures in each of which is accommodated a respective key of the keyboard/keypad. The transparent plate comprises an integral lens aligned with a reflector for directing light from an external source into the plane of the plate. Various plane reflecting surfaces are provided for reflecting the light in a localized path completely surrounding each of the apertures. This arrangement enables the keys to be illuminated with a high degree of uniformity using only relatively few distributed light sources.
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Citations
14 Claims
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1. A light guide for illuminating an information-bearing member, comprising:
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a transparent plate having at least one area associated with the information-bearing member, the plate having means for reflecting light from an external light source into the plane of the plate, wherein the reflecting means comprises first reflecting means for directing light from the light source in a first direction in the plane of the plate, second reflecting means for reflecting light from the first reflecting means in a second direction transverse to said first direction and in the plane of the plate, third reflecting means for reflecting light from the second reflecting means in a third direction transverse to the second direction and substantially parallel but in the opposite sense to the first direction and in the plane of the plate, and fourth reflecting means for reflecting light from the third reflecting means towards said first reflecting means in a fourth direction transverse to said first and third directions and substantially parallel but in the opposite sense to the second direction and in the plane of the plate. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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Specification