| 摘要 |
<p>PROBLEM TO BE SOLVED: To make it possible to continuously supply current of a light emitting diode in its maximum rated current through an illuminating period, even if the voltage of a capacitor falls, and also to level the load on the power supply. SOLUTION: When a 1st step release RL1 is turned ON, a central processing unit CP1 makes a booster circuit DD1 in an operation state, and makes electricity charging to a main capacitor C1 by the boosted output start. When a 2nd step release RL2 is turned ON, operation of the booster circuit DD1 stops, and the charging to the main capacitor C1 suspends. When a shutter is opened, the central processing unit CP1 makes a constant current circuit CC1 operate, and makes the light emitting diode LD1 emit light by predetermined constant current to light emitting diode LD1 for illumination. By electric discharging accompanying the luminescence, although the terminal voltage of the main capacitor C1 falls, the current which flows the light emitting diode LD1 is maintained at the current value near the maximum rated by the constant current circuit CC1. When the shutter begins to close, the constant current circuit CC1 is made non-operative and the light emitting diode LD1 is made to switch OFF.</p> |
