| 摘要 |
<p>PURPOSE:To obtain an excellent composite video signal by providing a D/A converter circuit having 1st and 2nd output terminals through which the composite video signal including a digitized video signal and a synchronizing signal is received and a complementary current output is outputted and outputting an output of each output terminal to a 3rd output terminal selectively. CONSTITUTION:A D/A converter circuit 2 receives a composite video signal digital data including an 8-bit video signal and a synchronizing signal from a signal source 1 and outputs an analog signal as a positive current output from a 1st output terminal 3 and as a negative current output from a 2nd output terminal 4 simultaneously. A switch control section 8 is provided with a signal source 8a and an inverter 8b, a 1st switch 6 is turned on and a 2nd switch 7 is turned off for the video display period of the composite video signal and the switches are set in the reverse state for the blanking period to allow the D/A converter circuit to output an output signal alternatively from either the 1st output terminal 3 or the 2nd output terminal 3 to a 3rd output terminal 5 thereby obtaining a composite video signal. Thus, the synchronizing signal is accurately set.</p> |
