| 摘要 |
PURPOSE:To save consuming current and to secure the response characteristics of a storing circuit by charging a storage capacitor rapidly and directly from a power source only when a power switch is turned on. CONSTITUTION:With a shutter button 66 turned on, a power switch 62 is closed and electric power is supplied to a photometric circuit 2 and a rapid charging circuit 30. The circuit 2 outputs a voltage signal, indicating adequate exposure time corresponding to a preset aperture value, to the circuit 30, and an operation amplifier 34 compress it with the voltage level of the storage capacitor 36. In this case, the capacitor 36 is charged directly with a current passed through a transistor TR46 and when the charging voltage rises up to a prescribed value, the output of the circuit 34 is inverted to turn off the TR46. Then, the capacitor 36 is charged with a current from a buffer circuit 32 up to the output voltage of the circuit 2, and its level then follows up a photometric output. When a shutter is released, exposure time control is exercised which corresponds to the voltage of the capacitor 36. |
