Patent ID: 7671848

Claim:
A display device for displaying an image and receiving light simultaneously or alternately, said display device comprising: a plurality of display elements for displaying the image on a display surface of said display device by emitting light; a plurality of light receiving elements for receiving light incident on the display surface formed by said display elements; a storing unit for storing, as an initial value, a difference between two amounts of light received by said light receiving elements when said display elements emit light and when said display elements do not emit light in a state of nothing being in contact with or in proximity to said display surface; and a detecting unit for detecting a state of contact with or proximity to the display surface by detecting an amount of light received by said light receiving elements when said display elements emit light and detecting an amount of light received by said light receiving elements when said display elements do not emit light, and subtracting said initial value stored by said storing unit from a difference between the two detected amounts of received light.