Facsimile drive with dynamic brake
OwnerJames G. Michnerinventor
Life of this patent
Estimating the term…
Abstract
In a facsimile transceiver, the scanning drum is driven by a DC motor which is coupled to a source of drive pulses having a duty cycle which controls the speed of the DC motor. Dynamic braking pulses are applied to the motor between the drive pulses. The braking current pulses are generated as a result of armature counter EMF and flow through a low impedance path around the DC motor.
Claims10
A facsimile unit comprising scanning means, information transducer means associated with the scanning means for scanning through various positions, and scanning drive means for driving the scanning means, said scanning drive means comprising a DC motor and a source of a pulsating drive voltage coupled to said DC motor for applying drive pulses to said DC motor during the duty cycle of the pulsating drive voltage, the improvement in said scanning drive further comprising
- dynamic brake means for intermittently applying a pulsating braking current comprising brake pulses between said drive pulses.
A facsimile unit comprising scanning means, information transducer means associated with said scanning means for scanning through various positions, and scanning drive means for driving said scanning means, said scanning drive comprising a DC motor and a source of pulsating drive coupled to said DC motor for applying drive pulses to said DC motor during the duty cycle of the pulsating drive, reference means for generating a reference signal representing the desired scanning speed of said scanning means, detector means for generating a speed indicative signal representing the actual scanning speed, and comparison means for comparing the reference signal and the speed indicative signal and varying the duty cycle of the pulsating drive so as to reduce the difference between the desired scanning speed and the actual scanning speed, the improvement in said scanning drive further comprising:
- dynamic brake means for intermittently applying pulsating braking current comprising braking pulses between said drive pulses, the duration of said braking pulses varying inversely with the duty cycle of said pulsating drive so as to further reduce the difference between the desired scanning speed and the actual scanning speed.
In a facsimile unit, a method of driving scanning means including a DC motor associated with the information transducer means and document and/or copy means comprising:
- driving the DC motor with a pulsating drive voltage comprising a plurality of drive pulses applied to the DC motor during the duty cycle of the pulsating drive signal;
- and
- braking the DC motor with a pulsating braking current comprising a plurality of braking current pulses applied to the DC motor between the drive pulses.
Dependencies are inferred from the claim text.