US Patent 7889158 Electrooptic device and electronic device

An electrooptic device includes: a first panel; a second panel on the back of the first panel; a first receiver circuit that measures a first ambient light incident on the first panel; a second receiver circuit that measures a second ambient light incident on the second panel; and a control circuit that measures the brightness of the environment where the first panel is placed on the basis of the luminance of the first ambient light whose ratio to that of the second ambient light is at or below a predetermined value, and that controls the display state of an image displayed on the first panel on the basis the brightness of the environment.