| 摘要 |
PURPOSE:To attain a picture easy to see always with a proper contrast by controlling the contrast of a picture in display by means of light-receiving element disposed around a picture displaying part. CONSTITUTION:The light-receiving element 3 is provided in the central part of the upper adjacence of the picture displaying part 2 with its light receiving plane in the same direction with that of the picture displaying plane of the part 2. The said element 3 detects the brightness around the part 2 of a liquid crystal television 1. When the intensity of the light received by the element 3 is high, the amplitude of a video signal Vs is made smaller, but if the said intensity is low, the said amplitude is made larger. The video signal whose amplitude is varies as above-mentioned is supplied to the driving circuit of the picture displaying part 2. As a result, when the luminance around the part 2 is high, the contrast of the picture display is made weak. But when the said brightness is low, the said contrast is made strong.
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