| 摘要 |
The motor is to be controlled to execute steps having a preselected step length. A displacement transducer is coupled to the motor and furnishes a displacement signal having a constant first predetermined value during motor movement by a predetermined fraction of said step length and changes to a second predetermined value during motor movement by the remainder of the step length. A voltage divider circuit and a differentiator circuit are connected to the output of the transducer and furnish a proportional and a differentiated signal. The two signals are combined in an operational amplifier whose output serves as a control signal for controlling the operation of the motor. The transducer includes three light transmitter-receiver pairs which are switched on in a first sequence when the motor rotates in one direction and in a second sequence for rotation in the opposite direction. The light passing from each transmitter to receiver is controlled by a diaphragm which has a pattern comprising a light transmissive portion extending for half a step length, a light transmissive to light blocking transition extending over a full step and a light blocking portion extending over a half a step. All the light receivers are tied together at a common point and a selector circuit selectively energizes the transmitter-receiver pairs so that each furnishes a partial signal which, when added to the other partial signals forms the complete displacement signal. The selector circuit is responsive to step initiating signals. If a monitoring circuit is provided to furnish "step performed" signals each indicative of a performed step and if these step performed signals are applied to the selector circuit to constitute the step initiating signals, then synchronism between the motor motion and the displacement transducer can be maintained and the motor can readily be switched from a position-uncontrolled to a position-controlled mode.
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