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:
Feb. 07, 1989
Filed:
Feb. 07, 1986
Shigeru Shinohara, Katsuta, JP;
Shun Suzuki, Katsuta, JP;
Hitachi Koki Company, Ltd., , JP;
Abstract
A speed controller for a DC motor includes a semiconductor switching device connected in series with it in a DC power circuit. The switching circuit is turned on and off with a duty ratio variable as a function of motor load. A time constant circuit including a capacitor is connected in parallel with the switching device to develop a voltage which is compared with a reference variable between high and low levels in response to the exceedance of the varaible reference. The switching device is turned on when the voltage developed by the capacitor is higher than the lower reference voltage to energize the motor, and is turned off when the capacitor voltage is lower than the higher reference voltage to de-energize the motor. The on-duty period of the motor is variable as a function of a motor-load representative voltage developed in the switching device during its turn-on period and the off-duty period is variable as a function of a counter-electromotive force generated in the motor as inversely proportional to motor load.