Telegraphy – Systems – Position coordinate determination for writing
Patent
1993-03-25
1994-10-25
Chin, Stephen
Telegraphy
Systems
Position coordinate determination for writing
178 87, 345173, 345175, 345176, G08C 2100
Patent
active
053591550
ABSTRACT:
An illumination apparatus is provided for an opaque digitizer tablet. The illumination apparatus can be used to convert the opaque digitizer into a back-lit digitizer. The illumination apparatus includes an aperture fluorescent lamp located peripheral to the portion of the working surface used for placement of the an object to be digitized and includes a non-optical-fiber flat light conductor (a slab waveguide) located on top of and covering the portion of the working surface used for the object to be digitized. Light conducted from the lamp emerges from the top surface of the non-optical-fiber flat light conductor for back lighting the object to be digitized. A reflective surface is located under the non-optical-fiber flat light conductor for reflecting scattered light, that emerges from a bottom surface of the non-optical-fiber flat light conductor, toward the object to be digitized. For optimum back lighting, the bottom surface of the non-optical-fiber flat light conductor includes a pattern of roughened portions which includes a region of lesser roughness nearer to the light source and a region of greater roughness farther from the light source. A panel-shaped optical conveyance is used to convey light from the light source to an edge of the non-optical-fiber flat light conductor. The roughened portions provide a slab waveguide with an imperfect boundary.
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Chin Stephen
Loomis Paul
Tiger Scientific Corp.
Towsend Marvin S.
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