| 摘要 |
PURPOSE:To enable the precise control of oscillation of an inverter by detecting a waveform change from the current waveform in normal state and judging whether the state of a discharge lamp is normal or not when the state of the discharge lamp is changed from the normal state. CONSTITUTION:A first main transistor Q1 and a second transistor Q2 are connected in series to a DC power source E, a detection resistance R1 is connected on the emitter side of the main transistor Q1, a diode D1 is connected in reverse parallel to a series circuit of the main transistor Z1 and the detection resistance R1, and a diode D2 is connected in reverse parallel to the main transistor Q2. These two main transistors Q1, Q2 are alternately turned on and off by drive circuits 10, 20, respectively. In this case, when the state of discharge lamps DL1, DL2 is changed from normal state, the waveform change from a current waveform in the normal state is detected, and whether it is normal or not is judged. Hence, according to this result, the oscillation of an inverter can be precisely controlled. |
