| 摘要 |
PURPOSE:To improve the utilization efficiency of a power source by a simple constitution by outputting a closing reference signal of a shutter and an opening reference signal being larger than its closing reference signal by detecting an opening/closing signal of a shutter of a copying machine, using the closing and opening reference signals as a control reference signal by synchronizing with closing and opening of this shutter and switching a gate means. CONSTITUTION:A voltage which has been converted to a DC by a rectifier 2 of a light source use power unit is converted to a high frequency AC by a switching circuit 4, its voltage is converted to a DC by a rectifier 11 and supplied to a projection lamp 16 and copying is executed. By a shutter opening/closing detecting device 23 of this copying machine 22, opening and closing of a shutter are detected and a shutter detection signal is outputted to a signal switching circuit 24. Also, a current flowing to the lamp 16 is detected by a current detector 18 and applied to an error amplifier 20. To this amplifier 20, a closing reference signal from variable DC power sources 26, 25 which have been switched, based on an opening/closing signal of the shutter or an opening reference signal being larger than said reference signal is applied, and by an output which has been outputted from the amplifier 20, a driving control circuit 21 is controlled. |
