Display device including function to input information from screen by light

Abstract

In order to enhance accuracy of determination as to whether an object has contacted a screen and to enhance accuracy of calculation of a coordinate position of the object, edges of an imaged image are detected by an edge detection circuit, and by using the edges, it is determined by a contact determination circuitwhether or not the object has contacted the screen. Moreover, in order to appropriately control sensitivity of optical sensors in response to external light, by a calibration circuit, a drive condition of the optical sensors is changed based on output values of the optical sensors, which are varied in response to the external light.