| 摘要 |
PURPOSE:To aim at safety in a way of cutting off an electric current in time of motor locking, by starting a timing motion in time of motor energizing but stopping it in time of motor stopping, while making a device generate a stop signal if the motor energizing continues for the setting time long from the start of the motor energizing. CONSTITUTION:In a safety circuit 90, a transistor 91 turns to OFF when relay coils 22a and 71a of a motor driver 70 are energized with current L and thereby a condenser 93 is charged as specified. When it passes through t1, it goes beyond reference voltage V1 of a comparator 95, and output of this comparator 95 turns to H whereby output of a motor 40 goes up, thus an arm is driven into rotation by strong force. Accordingly, even if the required driving force of a head lamp grows large due to lost motion, wear, etc., the specified drive is performable. In addition, when it comes to t2, voltage of the condenser 93 goes beyond reference voltage V2 and thereby output of a comparator 94 comes to H, turning a transistor 96 to ON, and transistors 74 and 76 come to L so that a continuous rating current for relay coils 72a and 71a is cut off, thus the motor stops. With this constitution, in time of trouble happening, it stops automatically before the motor generates heat, thus a device mechanism is protected. |
