| 摘要 |
PURPOSE:To bring a transistor inverter to a nonoperative condition positively by using a switch with small current capacity by a system wherein the base currents of the transistors of the inverter are limited when the abnormality of the inverter or load energized by means of said inverter is detected. CONSTITUTION:Power is supplied to a transistor inverter 4 consisting of transistors Tr5, 6, an inverter transformer 7 and a capacitor 8 for resonance from a DC power source 1, and the load of a discharge lamp 14 is made ON. A protective circuit 19 having a detecting portion 20 consisting of a heat sensitive thyristor e.g. is formed between each emitter of the Tr5, 6 and a contact point at the nonpower source side of a resistor 10 for supplying a base power source. Thus, when the detecting portion 20 senses the heat of constituent parts abnormally generating heat in case of the abnormality of the inverter 4 or the load 14 and is electrically conducted, portions between the bases and emitters of the Tr5, 6 are short-circuited, base currents are limited, and the inverter can be brought to a nonoperative condition. |
