| 摘要 |
PURPOSE:To obtain a video signal easy to see by using a photosensitive element to detect the luminance change of a light source, changing the amplification factor by the detection signal to prevent generation of a flicker based on the flickering of the light source. CONSTITUTION:Light passed throngh a lens l is formed on an iamge pickup face of an image pickup device 2, where the light is converted into an electric signal, vertical/horizontal synchronizing signals from a synchronizing signal generator 3 are added and fed to a variable amplifier 7. On the other hand, the detection signal of external light from a hhotosensitive element 5 and the synchronizing signal from the generator 3 are led to a control circuit 6. The circuit 6 uses a timing signal 12 from the generator 3 to apply A/D conversion 8 to the output of the element 5, stores data corresponding to the frame period time in a memory 9, each integration value of the memory 9 is added (10), the reciprocal number of the sum is calculated to obtain an amplification factor control signal of the amplifier 7. As a result, a video signal whose amplification factor is constant is transmitted from the amplifier 7.
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