| 摘要 |
PURPOSE:To miniaturize and lighten the titled device by reducing the number of transistors by a method wherein the load voltage of current control transistors is controlled at a value less than a prescribed one. CONSTITUTION:The negative pole of a thyristor rectifying circuit 21 is connected to the cathode 13 of a laser tube 10 through a transformer 4, and the positive pole is connected to the anode 12 of the laser tube 10 through a choke coil 2, the current control transistors 5, a current detection resistor 6, and a trigger circuit 9. Resistors 19 and 20 are connected in parallel between the collector and emitter of the current control transistors 5, and the connect point thereof is connected to a comparator 16. The comparator 16 is connected to a thyristor control circuit 17 and controls terminals a-c' of the rectifying circuit 21. Generally, the difference voltage between the voltage of a reference power source 8 and the output voltage of the resistor 6 is amplified in a comparing amplifier 7 and so controlled by the transistors 5 that the difference voltage becomes ''0''. When the voltage between the collector and emitter of the transistors 5 exceeds the prescribed value, it is detected, and the output voltage of the rectifying circuit 21 is reduced by the control circuit 17. |
