Optical touch screen with a lossy dispersive FTIR layer
First Claim
1. A touch sensitive screen arrangement comprising a screen including an optically dispersive base plate, and means for transmitting light onto and into said base plate in response to an external body touching said screen at a touch point such that the location of incident light on the surface of said base plate is representative of the relative position of said touch point on said screen, wherein said base plate is configured to capture and transmit within the base plate light incident thereon and disperse said transmitted light by spreading and energy loss, the optically dispersive characteristic of said base plate being such that the decrease in intensity of said transmitted light with distance from said location of incidence on said base plate surface approximates a substantially exponential function, the arrangement further comprising at least one sensor for detecting intensity of light transmitted out of the base plate at a respective edge of said base plate, and processing means for calculating the relative position of said touch point on said screen from said detected light intensity and said exponential function and generating a control signal representative of a control input derived from said position of said touch point;
- wherein said base plate comprises an optically transparent substrate doped with optically refractive and reflective particles or molecules; and
wherein the gradient of said exponential function is dependent on the level of doping of said base plate with said optically refractive and reflective particles or molecules.
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Accused Products
Abstract
A touch sensitive screen arrangement includes an optically dispersive base plate and structures for transmitting light onto the base plate in response to an external body touching the screen at a touch point such that the location of incident light on the surface of the base plate is representative of the relative position of the touch point on the screen. The base plate captures and disperses light that is incident on it. The decrease in incident light intensity with distance from the location of incidence on the base plate approximates a substantially exponential function. A sensor detects intensity of light at a respective edge of the base plate. The arrangement calculates the relative position of the touch point on the screen from the detected light intensity and the exponential function and generates a control signal representative of a control input derived from the position of the touch point.
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Citations
13 Claims
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1. A touch sensitive screen arrangement comprising a screen including an optically dispersive base plate, and means for transmitting light onto and into said base plate in response to an external body touching said screen at a touch point such that the location of incident light on the surface of said base plate is representative of the relative position of said touch point on said screen, wherein said base plate is configured to capture and transmit within the base plate light incident thereon and disperse said transmitted light by spreading and energy loss, the optically dispersive characteristic of said base plate being such that the decrease in intensity of said transmitted light with distance from said location of incidence on said base plate surface approximates a substantially exponential function, the arrangement further comprising at least one sensor for detecting intensity of light transmitted out of the base plate at a respective edge of said base plate, and processing means for calculating the relative position of said touch point on said screen from said detected light intensity and said exponential function and generating a control signal representative of a control input derived from said position of said touch point;
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wherein said base plate comprises an optically transparent substrate doped with optically refractive and reflective particles or molecules; and wherein the gradient of said exponential function is dependent on the level of doping of said base plate with said optically refractive and reflective particles or molecules. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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Specification