| 摘要 |
PROBLEM TO BE SOLVED: To provide a liquid crystal display device to be set up especially in a place where illumination is partially varied by shades caused by comings and goings of people and objects in relation to a technique to automatically dim a backlight of the liquid crystal display device corresponding to brightness and darkness of external light illumination. SOLUTION: Optical sensor groups 111-112 are disposed on the liquid crystal panel display surface side of a casing of the liquid crystal display device keeping a distance between each other, for example, on both sides of the liquid crystal panel and detect the external light illumination which is then subjected to digital conversion by an A/D converter 12. An ROM 14, in which an operation program, comparing the digital converted external light illumination data of the optical sensor groups 111-112 with each other and making backlight luminance vary only when both data vary to the same extent and not vary when only one of them is abnormal, is stored, carries out computing at established periods with a computing device 13 and an RAM 15. Thereby, in an automatic dimming device of the liquid crystal backlight utilizing the optical sensor, in which the backlight is automatically dimmed corresponding to variation of the external light illumination, difficulty associated with the fact that the backlight is automatically dimmed even when illumination is partially varied only on the periphery of the optical sensor and a dimming operation corresponding to variation of illumination in the room is not realized is solved. COPYRIGHT: (C)2005,JPO&NCIPI
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