| 摘要 |
PURPOSE:To regulate tire lower limit of lamp currents, and to eliminate lighting failure by controlling a high-frequency generator corresponding to the lowest lamp current of the lamp currents in each discharge lamp in lighting in parallel a plurality of discharge lamps. CONSTITUTION:A high-frequency generator 1 is operated by turning on a direct- current power supply 2 to light discharge lamps 3a-3e. In this case, these lamp currents are detected by current detecting means 7a-7e and are rectified by detecting circuits 8a-8e. In addition, the lamp currents are converted into voltage signals by means of current.voltage converting means 9a-9e, and are inputted to each error amplifier 11a-11e. The highest signal is outputted from the amplifier received the lowest lamp current, for example, the amplifier 11e. Thus, an oscillator 12 controls the high-frequency generator 1 corresponding to the signal from the amplifier 11e to retain tire lamp current of the discharge lamp 3e to a predetermined value. Therefore, no discharge lamps generating lighting failure will exist even if dimming lighting is applied to the discharge lamps 3a-3e. |
