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.

Date of Patent:
Jan. 17, 1995

Filed:

Aug. 02, 1993
Applicant:
Inventor:

Kyoung-Hwan Kim, Boocheon, KR;

Assignee:
Attorneys:
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
G11B / ;
U.S. Cl.
CPC ...
360 70 ; 360 7301 ;
Abstract

A drum servo system controls rotation of a head drum stably, even though a DFG signal has been dropped out. The drum servo system includes a DFG signal dropout detector for detecting the dropout of the DFG signal to generate first and second switching signals according to the detection. A digital-to-analog converter generates a drum motor driving voltage in dependence upon the first switching signal when the DFG signal is in a normal state and upon the second switching signal when the DFG signal is in an abnormal state. When the DFG signal is in the abnormal state, a previous state of the DFG signal is used for generating the drum motor driving voltage so that the head drum may rotate stably regardless of the dropout of the DFG signal.


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