The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Sep. 28, 1982
Filed:
Jan. 11, 1980
Stephen H Smith, Playa del Rey, CA (US);
Hybricon Inc., North Hollywood, CA (US);
Abstract
Method and apparatus are disclosed herein for controlling the voltage supplied to a motor to vary the speed thereof. A pulsewidth modulator is supplied a sawtooth waveform from a waveform generator and is controlled by an input signal to provide a variable duty cycle pulse train. The waveform generator also provides a start pulse which triggers an output driver circuit. The output driver circuit provides base current to a plurality of paralleled output transistor stages, which may be Darlington pairs, connected to the motor. The collector voltage of the output stages is monitored and, if it drops below a predetermined threshold at the edge of saturation, is clamped to a voltage and the edge of saturation, thereby preventing the output transistors from operating in saturation while at the same time minimizing the voltage across the collector of the output stages. This arrangement eliminates the need for emitter resistors while at the same time providing for high speed operation and better load sharing among the paralleled output transistors.