<p>Provided is a display device having a plurality of optical sensors arranged on a display panel. The display panel can be operated by touching the panel with a finger or a pen. A liquid crystal panel (11) having built-in sensors includes a plurality of pixel circuits (1) and a plurality of optical sensors (2) which are arranged two-dimensionally. An MPU (18) selects a mode for detecting a shadow image of an object or a mode for detecting a reflected image of the object according to the illuminance of the outside light. One frame period is divided into a display period and a sensing period. A backlight (14) is controlled to be ON during the display period of the shadow mode and the sensing period of the reflected image mode and OFF during the sensing period of the shadow mode and the display period of the reflected image mode. Thus, it is possible to increase the detection accuracy of the touch position while suppressing the power consumption by the backlight.</p>
