PROTECTION CIRCUIT OF CRT

摘要

PURPOSE: The protection circuit of CRT(Cathode Ray Tube) is provided to protect CRT by removing high residual light generated in the CRT of a large-sized projection TV. CONSTITUTION: A vertical blanking pulse part(20) generates a vertical blanking pulse signal from a video signal. A vertical pulse discrimination part(21) determines whether the vertical blanking pulse is output. A horizontal blanking pulse part(22) generates a horizontal blanking pulse signal from a video signal. A horizontal pulse discrimination part(23) determines whether the horizontal blanking signal is output. A power-supply unit(24) provides power-supply to a whole circuit. According to an output signal of the horizontal pulse discrimination part(21) or the horizontal pulse discriminator(23), the vertical/horizontal discrimination part(25) cuts off a main voltage relay of the power-supply unit(24), or provides an output signal of the discrimination part to a microcomputer terminal if the horizontal or vertical blanking signal is mute.