| 摘要 |
PROBLEM TO BE SOLVED: To reduce power consumption while keeping sufficient luminance even when a signal is always inputted by lighting only a specified light source body by a light source control part and irradiating only the specified range of a liquid crystal display part. SOLUTION: The video signal of one horizontal scanning period is sampled at the rising of a clock pulse, and displayed on the liquid crystal display part 6 in synchronization with the timing of the sampling. When the sampling is performed with the clock pulse whose frequency is lowered to 1/2, a picture reduced to 1/2 in a horizontal direction is displayed. In order to reduce the longitudinal dimension of the picture, the horizontal scanning of the video signal is thinned. A write control pulse repeats a period when a pixel can be written and a period when it can not be written. The picture thinned on every horizontal scanning, that means, the picture whose longitudinal dimension is reduced to 1/2 is displayed on the picture display device. At such a time, by lighting light emitting diodes 1 to 3, the reduced picture 8 whose area is 1/ 4 of the original one is obtained.
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