Optical touch-screen systems and methods using a planar transparent sheet
First Claim
1. A touch-screen system for sensing a location of a touch event, comprising:
- a transparent sheet having a top surface, a bottom surface, and a perimeter that includes an edge, wherein the touch event occurs on the top surface;
a plurality of light-source elements that emit light and that are disposed adjacent the perimeter either adjacent the edge or adjacent the bottom surface substantially at the edge, so as to couple the light into the transparent sheet to travel therein via total internal reflection;
a plurality of light-sensing elements operably disposed only adjacent the edge to detect the light that travels within the transparent sheet and along lines-of-sight from each of the light sources to the light-sensing elements, the light-sensing elements each being configured to generate detector signals having a signal strength representative of a detected light intensity, wherein the touch event causes attenuation of the light intensity along at least one of the lines-of-sight;
a slab waveguide in contact with the bottom of the transparent sheet and disposed only adjacent the edge and between the bottom of the transparent sheet and at least one of the light-sensing elements such that the lines-of-sight pass from the transparent sheet through the slab waveguide and to the at least one of the light-sensing elements even in the absence of the touch event; and
a controller operably coupled to the light-source elements and the light-sensing elements and configured to control the emission of the light from the light-source elements and process the detector signals to compare the detector signal strength to a signal threshold to establish attenuated lines-of-sight.
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Accused Products
Abstract
An optical touch screen that utilizes a planar transparent sheet and that is configured to determine the position of a touch event on the transparent sheet is disclosed. Light-source elements and light-sensing elements are operably disposed at a perimeter of the transparent sheet. Light is detected over lines-of-sight between the light-source elements and the light-sensing elements. Attenuated lines-of-sight due to the touch event are determined. Central lines are established based on the attenuated lines-of-sight. The locations of central-line intersections are then established. The average of the locations of the central-line intersections is then used to establish the location of the touch event.
157 Citations
18 Claims
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1. A touch-screen system for sensing a location of a touch event, comprising:
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a transparent sheet having a top surface, a bottom surface, and a perimeter that includes an edge, wherein the touch event occurs on the top surface; a plurality of light-source elements that emit light and that are disposed adjacent the perimeter either adjacent the edge or adjacent the bottom surface substantially at the edge, so as to couple the light into the transparent sheet to travel therein via total internal reflection; a plurality of light-sensing elements operably disposed only adjacent the edge to detect the light that travels within the transparent sheet and along lines-of-sight from each of the light sources to the light-sensing elements, the light-sensing elements each being configured to generate detector signals having a signal strength representative of a detected light intensity, wherein the touch event causes attenuation of the light intensity along at least one of the lines-of-sight; a slab waveguide in contact with the bottom of the transparent sheet and disposed only adjacent the edge and between the bottom of the transparent sheet and at least one of the light-sensing elements such that the lines-of-sight pass from the transparent sheet through the slab waveguide and to the at least one of the light-sensing elements even in the absence of the touch event; and a controller operably coupled to the light-source elements and the light-sensing elements and configured to control the emission of the light from the light-source elements and process the detector signals to compare the detector signal strength to a signal threshold to establish attenuated lines-of-sight. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method of determining a location of a touch event on a transparent sheet, comprising:
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sending light from light-source elements to light-sensing elements over lines-of-sight therebetween, wherein the light-source elements and light-sensing elements are operably disposed only adjacent a perimeter of the transparent sheet, wherein the light travels within the transparent sheet via total internal reflection; disposing the light-sensing elements adjacent a slab waveguide that resides only adjacent the perimeter of the transparent sheet and that is in contact with a bottom surface of the transparent sheet such that the lines-of-sight pass from the transparent sheet through the slab waveguide and to the light-sensing elements even in the absence of the touch event; determining the lines-of-sight over which light is attenuated by the touch event, thereby defining attenuated lines-of-sight; defining a central line for the attenuated lines-of-sight associated with each light-sensing element; determining locations of intersections of the central lines; and averaging the locations of the intersections of the central lines to establish the location of the touch event. - View Dependent Claims (9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
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Specification