Patent ID: 7602380

Claim:
A display device with an optical input function comprising: a plurality of scanning lines arranged in parallel, a plurality of signal lines arranged to intersect with the plurality of scanning lines, a plurality of pixel portions arranged at intersecting portions between the plurality of scanning lines and the plurality of signal lines, photosensor portions provided at least one for each or every preset number of the plurality of pixel portions, a pixel drive section which drives the plurality of pixel portions via the plurality of scanning lines and the plurality of signal lines, a sensor drive section which drives the photosensor portions, an operation processing section which is supplied with outputs of the photosensor portions and derives information of an area of a light receiving area on a display screen by use of photosensing signals when light from a tip end of a light source is illuminated on the display screen, and a determining section which determines that the light source is set in contact with the display screen when the following conditions (a), (b), and (c) are satisfied, (a) a first operating section which compares the information of the area of the light receiving area with a specified area reference value and calculates a deviation amount from the reference value, wherein the deviation amount from the reference value is smaller than a first specified threshold value of the deviation amount, (b) a second operating section which calculates a variation amount of the area of the light receiving area with time, wherein the variation amount with time is smaller than a second specified threshold value of the variation amount with time, and (c) a third operating section which calculates a degree of roundness of the light receiving area based on the area and a peripheral length of the light receiving area, wherein the degree of roundness is larger than a third specified threshold value of the degree of roundness.