OPTICAL TOUCH SCREEN WITH A LOSSY DISPERSIVE FTIR LAYER

摘要

A touch sensitive screen arrangement comprising a screen including an optically dispersive base plate(18), and means for transmitting light onto said base plate in response to an external body (22) 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 (18) is configured to capture and disperse light incident thereon by spreading and energy loss, the optically dispersive characteristic of said base plate being such that the decrease in intensity of said incident 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 (20) for detecting intensity of light 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.