| 摘要 |
PURPOSE:To simplify a device and to stabilize the generation of color frame signals by displaying the phase difference between a horizontal synchronzing signal, detected by a color frame detecting circuit, and a reference chrominance subcarrier and the phase difference between the both whose phase relation is varied by turns. CONSTITUTION:While synchronized 14 with frame pulse FP1 generated 8 from a color video signal by horizontal synchronizing signal HD' extracted by synchronous separating circuit 9, FP2 is inputted to clocks of T-FF15 and JK-FF16. A burst signal extracted by filter 18, on the other hand, is inputted to PLL19 and on the connection of a prescribed voltage or variable voltage to change-over switch 21, reference chrominance subcarrier SC obtained via variable delay circuit 20 is supplied to FF16 to obtain detection pulse DFP for the width of the phase difference between a horizontal synchronizing signal and SC or that between the both whose phase relation is varied. Then, color frame pulse FP3 is obtained at the output of FF-15 via DFP and the light emitting diode that corresponds to the pulse width of DFP is turned off for display 4, so that the generation of the frame signal will be stabilized by the simple device. |
