| 摘要 |
1. A control circuit for providing a vertical deflection saw tooth signal to a TV set comprising an input integrator (20-23) receiving the composite line synchronization signal and supplying a frame synchronization signal (ST), comprising a series of flipflops (B1, B2, B3) controlled by a signal (ST) and by a signal (H/2) having twice the frequency of the line deflection signal for supplying a frame saw tooth control signal at low level in the absence of signal (ST) and at high level in the presence of signal (ST) and from the rising edge of a first pulse of said double frequency signal (H/2) until the rising edge of a subsequent pulse of said double frequence signal (H/2), characterized in this that the series of flipflops comprises three flip-flops : a first flip-flop (B1) receiving at its input S the output of an AND gate (A1) in turn receiving the frame synchronization signal (ST) and the double frequency signal (H/2), receiving at its input R the inverted signal (ST), and supplying at its output Q a signal (STN), - a second flip-flop (B2) receiving the signal (STN) and supplying a short duration signal (RAZ) at its output Q, - a third flip-flop (B3) receiving the output of the second flip-flop (B2) at its input S and logic signals from the frame dividers at its input R for setting the output Q of said flip-flop (B3) at a high level during switching to high level of signal (RAZ) and at a low level during the third occurrence of a double frequency signal (H/2). |
