| 摘要 |
PURPOSE:To obtain a simplified, high-performance detector by providing a detecting means which detects the bulb current of a fluorescent lamp, and confirming whether the fluorescent lamp turns on or off by the output signal of the detecting means. CONSTITUTION:For example, when a 24V power source is applied to a point B, a heater control circuit 11 operates to turn on the heater of the fluorescent lamp 8. When a lighting signal rises to a high level, a transistor (TR) 1 turns on to operate a transmission control circuit 10, and a high frequency oscillating circuit 12 operates to turn on the fluorescent lamp 8. When the fluorescent lamp 8 is turned on, the bulb current flows to the fluorescent lamp and is detected by a bulb current detecting circuit 13, and the circuit 11 operates by its detection signal to turn on a TR2 while cutting off the heater current of the fluorescent lamp 8, outputting a lighting confirmation signal. Consequently, the need for the physical space of the detection part is almost eliminated, and the relatively large bulb current is detected, so the setting of a reference detection value is facilitated. |
