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:
Mar. 10, 1981
Filed:
Oct. 29, 1979
Steven D Keidl, Rochester, MN (US);
International Business Machines Corporation, Armonk, NY (US);
Abstract
Stepper motor control circuitry including a phase locked loop circuit formed by a phase detector outputted to a filter and a voltage controlled triangular and square wave generator which has a frequency control input terminal connected to the output of the filter and which provides a square wave on an output thereof connected as an input to the phase detector. An oscillator drives the phase detector, and the outputs of the generator are connected as inputs to a pulse width modulated driver which has its outputs connected to the coils of the stepper motor. A differential amplifier is connected across one of the coils of the motor, and a balanced modulator synchronous detector or multiplier has two inputs one of which constitutes an output of the differential amplifier and the other of which is a connection to the square wave output of the generator. The output of the multiplier constitutes an error signal which is supplied to a summing junction between the filter and generator so that, upon the application of an instantaneous load to the stepper motor, the error signal causes a very quick return to normal speed of the motor.