Patent ID: 9035909
Filing Date: 2015-05-19
Classification: G06F

Abstract:
1. An apparatus for determining a location of at least one object on a touch surface, the apparatus comprising: a light transmissive panel defining the touch surface and comprising a first layer and a second layer arranged intermediate the touch surface and an opposite surface, a controllable reflective boundary formed between the first layer and the second layer, an illumination arrangement configured to introduce light into the panel for propagation by internal reflection and for allowing the light to impinge on the touch surface, an electrical control device configured to selectively control the reflective boundary for forming a light-transmissive opening in the reflective boundary, such that at least a portion of the introduced light passes between the first layer and the second layer via the opening, a light detection arrangement configured to receive and measure an intensity of the light passed via the opening and impinged on the touch surface, and a processor unit configured to, when the object touches the touch surface and thereby attenuates the light passed via the opening and impinged on the touch surface, determine the location as a function of the measured light intensity and the selective control of the reflective boundary, wherein the first layer includes a refractive index different from a refractive index of the second layer, for forming the controllable reflective boundary, and wherein the control device is configured to form the opening by locally decreasing the difference in refractive indices of the first layer and the second layer.