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:
Nov. 18, 1997
Filed:
Oct. 24, 1995
Yasuyuki Ohnishi, Kyoto, JP;
Rohm Co. Ltd., Kyoto, JP;
Abstract
A motor controller of the present invention has a frequency generator which outputs, in accordance with a rotation of the motor, a predetermined number of rotational signals every time the motor makes one rotation. A period signal representative of the period of the rotational signals is calculated, and the period signal and a predetermined value are subtracted to obtain a speed error signal. The error signal is stored at a predetermined address of a memory. A filter which performs filtering by use of a plurality of error signals in the memory and a subtracter which subtracts the error signals and the contents of the memory are provided. A selecting circuit outputs the error signal when the error signal is outside a predetermined range and outputs an output of the filter when the error signal is within the predetermined range. Thereafter, the selecting circuit outputs an output signal of the subtracter. A control signal is produced from an output of the selecting circuit. The driving torque of the motor is varied in accordance with the control signal.