| 摘要 |
PROBLEM TO BE SOLVED: To improve detection accuracy even when external light illuminance is low in a liquid crystal display device which controls the brightness of a backlight by measuring the external light intensity around a liquid crystal display panel. SOLUTION: The liquid crystal display device comprises: the liquid crystal display panel; the backlight; a photo sensor; a photo sensor circuit that measures the external light illuminance around the liquid crystal display panel by using the photo sensor; and a control circuit that controls the backlight and the photo sensor circuit, wherein the control circuit periodically turns off the backlight and, at the same time, periodically outputs a control signal for starting the measurement of the external light illuminance around the liquid crystal display panel to the photo sensor circuit, and the photo sensor circuit measures the external light illuminance around the liquid crystal display panel within an illuminance measuring period within a turn-off period of the backlight based on the control signal, and the control circuit changes the illuminance measuring period in response to the external light illuminance measured by the photo sensor circuit. COPYRIGHT: (C)2007,JPO&INPIT |
