CIRCUIT TO LIMIT BEAM CURRENT OF CATHODE RAY TUBE

PROBLEM TO BE SOLVED: To make an image bright without causing any danger to a transformer in the case of an extreme load by acting a control circuit to reduce a beam current when a temperature sensor of the transformer senses a higher temperature than a prescribed temperature. SOLUTION: A voltage U3 is higher than a voltage U4 in a normal state and a point (c) is decoupled from a point (b) with a diode D1 biased reversely. When a temperature of a transformer Tr, that is, a temperature of a ferrite core 8 and a resistor R2 rises, the resistance of the resistor R2 is decreased to decrease the voltage U3. When the temperature exceeds a prescribed temperature, the voltage U3 is smaller than the voltage U4 and the diode D1 is forward- biased. Then part of a current from a resistor R3 flows through the diode D1 that is forward-biased and no longer flows to a high voltage winding 5. This depicts it that a threshold level of a beam current limiter is gradually reduced and transmitted power is reduced as desired.