Horizontal scanning phase control circuit for video monitor - includes two monostable multivibrators, one operated by return flanks of horizontal synchronising pulses

摘要

The monitor using colour as well as monochrome signals, and used with computers, uses a circuit for controlling the phase of horizontal scanning, receiving the horizontal sync pulses and with horizontal scanning circuit at its output. Two monostable multivibrators (1,2) are used, the first operated by the return flanks of the horizontal sync pulses (SH). Its time constant is smaller than a line period. The second monostable vibrator (2) is operated by the return flanks of the output pulses of the first monostable vibrator, its output forming the output of the system. The time constant of the first is adjusted according to the type of operation. The time constant of the second is greater than the line flyback time. ADVANTAGE - Phase position of horizontal flyback is stabilised in middle of blanking-out pulse and screen image is stabilised.