Positioning system for transport mechanism - uses difference between nominal and actual values of pulse period for motor voltage control

摘要

The transport mechanism is driven by a DC motor and moves a recording medium. It has a pulse generator coupled with the motor shaft; a counter storing the distance to the target position and a speed controller for the DC motor, whose reference element delivers a control variable depending on the counter reading. Pulses from the pulse generator are applied to a time measuring circuit which generates an actual value corresponding to the period of these pulses. The difference between the control variable which corresponds to the nominal period duration, and the actual value is the control deviation controlling the DC motor voltage.