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:
Aug. 05, 1980
Filed:
Mar. 03, 1978
Rudolf A van Dam, Eindhoven, NL;
Kornelis A Immink, Eindhoven, NL;
U.S. Philips Corporation, New York, NY (US);
Abstract
A tachometer system for supplying a control signal indicative of positional and/or speed errors of a rotatable element comprises a tachometer on which marks are arranged in a closed track and a detector responsive thereto to produce n tacho-pulses per revolution of the tachometer. The tachometer system further comprises a memory device with n locations in which n correction signals are stored. The correction signals are obtained by driving the tachometer at an accurately constant speed, measuring the phase difference between the tacho-pulses and the reference signal, and storing the phase-error signals related to the consecutive tacho-pulses in separate locations of the memory device. When the tachometer system is used in a servo control loop these correction signals are used to correct the phase-error signals then measured, yielding a correction in respect of the deviations in these phase-error signals owing to positional tolerances of the marks on the tachometer.