| 摘要 |
<p>An electric motor is connected to a device to be positioned and is controlled by a control circuit including a potentiometer device which provides a variable resistance in the control circuit. The potentiometer device may include a pair of potentiometers which are simultaneously controlled to control the direction and speed of the motor. The potentiometer device has a rotor and a stator, both of which are mounted for movement, with one part, such as the rotor, positioned by a stepping motor. The stepping motor may be operated by pulses from a pulse generator, and the pulses may also be applied to a counter. When a particular number of pulses are received, the counter can act to terminate the supply of pulses to the stepping motor so that it stops. The shaft of the drive motor is coupled to the other movable part of the potentiometer device, such as the stator, to return the parts to the initial relative position. The control circuit supplies current to the drive motor to energize the same when the parts are displaced from the initial relative position, and supplies no current when the parts are at such initial position to stop the motor.</p> |
