Systems For Resolving Touch Points for Optical Touchscreens
First Claim
1. A touch detection system, comprising:
- a reflector positioned along at least one edge of a touch area for reflecting light across the touch area;
a light detector having a field of view, wherein the light detector is positioned so that the field of view substantially encompasses the reflector;
a primary illumination source and a secondary illumination source, wherein the illumination sources provide a first light pattern and a second light pattern across the touch area; and
a computing device interfaced with the light detector, wherein the computing device executes computer-executable instructions for (i) receiving data signals from the light detector representing a first shadow on the reflector caused by an object touching the touch area at a touch point during a first time period and a second shadow on the reflector caused by the object touching the touch area at the touch point during a second time period, and (ii) determining coordinates of the touch point relative to the touch area based on said data signals.
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Abstract
An optical touch detection system may rely on triangulating points in a touch area based on the direction of shadows cast by an object interrupting light in the touch area. When two interruptions occur simultaneously, ghost points and true touch points triangulated from the shadows can be distinguished from one another without resort to additional light detectors. In some embodiments, a distance from a touch point to a single light detector can be determined or estimated based on a change in the length of a shadow detected by a light detector when multiple light sources are used. Based on the distance, the true touch points can be identified by comparing the distance as determined from shadow extension to a distance calculated from the triangulated location of the touch points.
103 Citations
60 Claims
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1. A touch detection system, comprising:
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a reflector positioned along at least one edge of a touch area for reflecting light across the touch area; a light detector having a field of view, wherein the light detector is positioned so that the field of view substantially encompasses the reflector; a primary illumination source and a secondary illumination source, wherein the illumination sources provide a first light pattern and a second light pattern across the touch area; and a computing device interfaced with the light detector, wherein the computing device executes computer-executable instructions for (i) receiving data signals from the light detector representing a first shadow on the reflector caused by an object touching the touch area at a touch point during a first time period and a second shadow on the reflector caused by the object touching the touch area at the touch point during a second time period, and (ii) determining coordinates of the touch point relative to the touch area based on said data signals. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19)
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20. A touch detection system, comprising:
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a reflector positioned along at least one edge of a touch area for reflecting light across the touch area; an optical assembly comprising a light detector, a primary illumination source and a secondary illumination source, wherein the light detector has a field of view and is positioned so that the field of view substantially encompasses the reflector, and wherein the primary illumination source is positioned a first distance from light detector and the secondary illumination source positioned a second distance from the light detector, such that the illumination sources can be controlled to emit a first light pattern and a second light pattern across the touch area; and a computing device interfaced with the optical assembly, wherein the computing device executes computer-executable instructions for (i) controlling the illumination sources to emit the first light pattern during a first time period and to emit the second light pattern during a second time period, (ii) receiving data signals from the light detector representing a first shadow on the reflector caused by an object touching the touch area at a touch point during the first time period and a second shadow on the reflector caused by the object touching the touch area at the touch point during the second time period, and (iii) determining coordinates of the touch point relative to the touch area based on said data signals. - View Dependent Claims (21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35)
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36. A touch detection system, comprising:
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a reflector positioned along at least one edge of a touch area for reflecting light across the touch area; an optical assembly comprising a light detector, a primary illumination source and a secondary illumination source, wherein the light detector has a field of view and is positioned so that the field of view substantially encompasses the reflector, and wherein the primary illumination source is positioned a first distance from the light detector and the secondary illumination source positioned a second distance from the light detector, such that the illumination sources can be controlled to emit a first light pattern and a second light pattern across the touch area; and a computing device interfaced with the optical assembly, wherein the computing device executes computer-executable instructions for (i) controlling the illumination sources to emit the first light pattern during a first time period and to emit the second light pattern during a second time period, (ii) receiving data signals from the light detector representing two first shadows on the reflector caused by a first object touching the touch area at a first touch point and a second object touching the touch area at a second touch point during the first time period, (iii) receiving data signals from the light detector representing two second shadows on the reflector caused by the objects touching the touch area at the touch points during the second time period, and (iv) determining coordinates of the touch points relative to the touch area based on said data signals. - View Dependent Claims (37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48)
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49. A touch detection system, comprising:
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a reflector positioned along at least one edge of a touch area for reflecting light across the touch area; a first optical assembly comprising a primary illumination source, a secondary illumination source and a first light detector having a first field of view, wherein the primary illumination source is positioned a first distance from the light detector and the secondary illumination source is positioned a second distance from the light detector, and wherein the first optical assembly is positioned so that the first field of view substantially encompasses the reflector; a second optical assembly comprising at least a second light detector having a second field of view, wherein the second optical assembly is positioned remote from the first optical assembly and such that the second field of view substantially encompasses the reflector; a computing device interfaced with the first optical assembly and the second optical assembly, wherein the computing device executes computer-executable instructions for (i) controlling the illumination sources to emit a first light pattern across the touch area during a first time period and to emit a second light pattern across the touch area during a second time period, (ii) receiving data signals from the first light detector and the second light detector representing a plurality of first shadows on the reflector caused by a plurality of objects touching the touch area at plurality of touch points during the first time period, (iii) receiving data signals from the first light detector representing a plurality of second shadows on the reflector caused by the plurality of objects touching the touch area at the plurality of touch points during the second time period, (iv) triangulating the plurality of first shadows to determine coordinates of potential touch points, and (v) determining coordinates of the touch points relative to the touch area based on said data signals and the coordinates of the four potential touch points. - View Dependent Claims (50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60)
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Specification