| 摘要 |
PURPOSE:To improve the temperature characteristic of an oscillating circuit suitable for a driving pulse generating circuit and starting oscillation always at the same phase in synchronizing with a trigger pulse by providing an oscillator, a frequency dividing circuit frequency-dividing an output pulse of the oscillator and an FF circuit. CONSTITUTION:The oscillator 50 starts oscillation at the same phase in synchronizing with the trigger pulse 16 and its oscillating frequency is controlled by a power supply voltage. A frequency dividing circuit (counter circuit) 51 frequency- divides an output pulse of the oscillator 15 into 1/m. Since a pulse generated from the frequency dividing circuit 51 is superimposed on a video signal and becomes a noise source deteriorating a screen, its operation is controlled by the FF circuit 54, causing the oscillator to be operated only at the outside of a horizontal blanking period not causing a video output. That is, the circuit 54 is set by a horizontal synchronizing pulse 16 and an operation command signal Q is given to the circuit only during the set period. The circuit counts an input pulse from the oscillator 50 accordingly and an output pulse in counting m set of pulses during the horizontal blanking period resets the circuit 54. |
