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. 20, 1983
Filed:
Apr. 22, 1981
Sidney W Marshall, Webster, NY (US);
Xerox Corporation, Stamford, CT (US);
Abstract
A tracking apparatus for the read/write head of a recording disk. Positive and negative servo marks on the disk provide sine and cosine head position signals. A calculator generates sine and cosine signal approximations from the high frequency signal outputs of variable and fixed frequency oscillators. A comparator compares the sine and cosine head position signals with the sine and cosine signal approximations and generates a corrective signal where a difference exists. The corrective signal is used to set the frequency of the variable frequency oscillator until the corrective signal is brought to zero. The signal outputs of variable and fixed frequency oscillators are fed to the up and down inputs of a head actual position counter. A second comparator compares the count on the counter with the count on a head desired position register to provide a servo error signal for operating a servo motor which moves the head to the desired track. A feedback loop supplements the corrective signal with a signal derived from actuation of the servo motor to enhance response.