| 摘要 |
<p>PURPOSE:To obtain more beautiful video image by making a reference voltage variable at each horizontal scanning period so as to change smoothly a pattern which is being changed stepwise. CONSTITUTION:A video signal (a) is inputted to a video input terminal 1. Similarly the video signal (a) is inputted to a synchronous separator circuit 4. Then a horizontal synchronizin signal (b) is outputted from the circuit 4. The output is led to a timing generating circuit 5 to generate an A/D conversion timing signal (c) and a signal (d) frequency-dividing the horizontal synchronizing signal by 1/2. The A/D converting circuit 2 applies A/D conversion to the video signal according to the A/D conversion timing of the timing generating circuit 5. The reference voltage 3 is used as a reference for the case. Then the referenece voltage is controlled by the signal (d) and threshold voltages A, B, C have different values at each horizontal scanning period. The output of the digital output terminals 6, 7 is shown as (e, f) in this case.</p> |
