| 摘要 |
PURPOSE:To prevent malfunction by detecting a power voltage, and then increasing a time constant by connecting two capacitors in parallel by turning on a switching circuit when the detected voltage drops down to a prescribed value. CONSTITUTION:As a power source 85 is used, its voltage drops, so a motor 1 rotates solwly. In this case, the rotation of the motor 1 is influenced easily by a load, and made slower and slower as the rotational angle of a shutter setting cam 48 nears 180 deg.. As a result, the pulse interval of a differentiating circuit 101 increases. As the load on the motor 1 increases, the voltage of the power source 85 drops and a voltage at a point B also drops accordingly to reduce the charging current of a capacitor 87 slightly, but the charging time is prolonged, so that a voltage at a point A rises. Therefore, the output of a comparator 88 is inverted at a point E to form a reversing circuit for the motor 1. |
