| 摘要 |
PURPOSE:To prevent abnormal operation of a lighting device so as to ensure safety by providing an input voltage supervisory circuit so as to force an inverter to stop actuation when the input voltage is abnormally lowered. CONSTITUTION:When the input voltage range becomes low, not more than 8.5V, a constant voltage diode ZD in an input voltage supervisory circuit 'A' becomes of a predetermined voltage or less, and a transistor Q7 is turned 'OFF'. The base of a transistor Q2 with which the collector of the transistor Q7 is connected through the resistance R1 and a diode D4 becomes 'High', whereby the transistor Q2 is turned 'OFF', and the Q3 is also turned 'OFF'. By the turning 'OFF' of the transistor Q3, switching transistors Q1, Q5 of an inverter transformer primary coil are turned 'OFF'. Actuation of the inverter is thus stopped. |
