Input device based on frustrated total internal reflection
First Claim
1. Apparatus for detecting the location of an object comprising, in combination,a transparent panel defining two opposing planar surfaces and having an index of refraction greater than air,a light detector optically coupled to said panel for detecting light transmitted within said transparent panel at a plurality of spaced apart detection points located at or near the periphery of said panel,a first light source optically coupled to said panel for transmitting light into said panel at an angle so that light from a first position propagates by internal reflection within said panel between said two opposing planar surfaces to a first set of said spaced apart detection points,a second light source optically coupled to said panel for transmitting light into said panel at an angle so that light from a second position propagates by internal reflection within said panel to a second set of said spaced apart detection points, anda data processor connected to said light detector for processing signals indicating changes in the light intensity at individual ones of said first and second sets of detection points to produce an output indication which specifies one or more locations on said surfaces where the presence of an adjacent object has caused a change in the internal reflection characteristics of said panel.
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Accused Products
Abstract
A touch panel in which two or more light sensors emit light into a transparent panel at an angle to sustain transmission through the panel by total internal reflection. The transmitted light is detected at an array of light detection positions around the periphery of the panel opposite to each light source. When an object contact the surface of the panel, light transmitted along the pathway from a given source past the contact point to one of the detection points is attenuated by the frustrated total internal reflection (FTIR) effect. Each contact causes two or more intersecting light beams having known end points to be attenuated, enabling a connected processor to determine the position and size of the contact area.
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Citations
20 Claims
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1. Apparatus for detecting the location of an object comprising, in combination,
a transparent panel defining two opposing planar surfaces and having an index of refraction greater than air, a light detector optically coupled to said panel for detecting light transmitted within said transparent panel at a plurality of spaced apart detection points located at or near the periphery of said panel, a first light source optically coupled to said panel for transmitting light into said panel at an angle so that light from a first position propagates by internal reflection within said panel between said two opposing planar surfaces to a first set of said spaced apart detection points, a second light source optically coupled to said panel for transmitting light into said panel at an angle so that light from a second position propagates by internal reflection within said panel to a second set of said spaced apart detection points, and a data processor connected to said light detector for processing signals indicating changes in the light intensity at individual ones of said first and second sets of detection points to produce an output indication which specifies one or more locations on said surfaces where the presence of an adjacent object has caused a change in the internal reflection characteristics of said panel.
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15. A touch sensitive device for determining the relative location of a point of contact between an object and a surface comprising, in combination,
a transparent panel defining said surface and an opposing surface, two or more light sources for transmitting light into said transparent panel at an angle to sustain transmission through said panel between said surface and said opposing surface by total internal reflection, sensing means for determining the intensity of light received at each of an array of light detection positions around the periphery of said panel, and means coupled to said sensing mean for identifying the attenuation of light transmitted along each one of plural intersecting light pathways, each of said pathways extending from an identified one of said light sources past said point of contact to an identified one of said light detection positions, processing means for processing data identifying said plural intersecting pathways for determining the location of said point of contact.
Specification