Importance

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Abstract

A stepping motor rate control employs a predetermined energization of one quantity to step the motor and a lower, predetermined quantity of current energization to hold the motor in position as by using a current pulse to hold the motor. The frequency of energization of the motor is constant; the speed of the motor being determined by the ratio of stepping pulses to holding pulses. The stepping motor rate control is driven from a clock. A duty cycle divider reduces the clock frequency down to the energizing frequency of the stepping motor. An energizing pulse is applied to the motor during each cycle. A divide-by-N-divider, coupled to the duty cycle divider, is used to determine the ratio of stepping energization pulses to holding energization pulses to be provided to the motor and hence the speed of the motor. The divide-by-N-divider operates a duty cycle control connected to the duty cycle divider which controls the width of the output pulses of the duty cycle divider and establishes the stepping pulse-holding pulse ratio in the output of the duty cycle divider. The control includes output circuitry which sequentially energizes the motor windings with the stepping pulses and repetitiously energizes the windings with the holding pulses. In a modification of the rate control, the operation of the control may be established by an external signal to coordinate the operation of the stepping motor with other apparatus.

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First Claim