| 摘要 |
<p>PURPOSE:To obstruct automatically a light emission of a discharge tube in case when a sufficient light quantity is obtained on the way of a light emission of a partial flash discharge tube, by making the operation of a delay ignition signal generating circuit impossible when a dimming signal is received from a dimming circuit. CONSTITUTION:When a reflected light from an object to be photographed reaches a correct light quantity, and a dimming signal of an ''H'' level is outputted from a dimming circuit C1, gates of a commutation thyristor SCR3 and SCR7 are triggered to an ''H'' level, respectively. As a result, the thyristor SCR3 and SCR7 are ignited at the same time, and by biased reverse between the anode and the cathode, and also between the cathode and the gate of a main thyristor SCR2 and SCR6. Accordingly, the main thyristor SCR2 and SCR6 are turned off suddenly, and a light emission of a flash discharge tube X1 and X2 is stopped. In this way, in case when a sufficient light quantity is obtained on the way of the light emission, the light emission of the discharge tube can be obstructed automatically.</p> |
