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:
Apr. 11, 1995
Filed:
Sep. 01, 1993
Kaneyasu Shimoda, Kawasaki, JP;
Fujitsu Limited, Kawasaki, JP;
Abstract
In a clock generator for magnetic disk drive of the zone-bit recording type in which a training signal is written in a preamble portion of data, comprising: a sample-holder circuit for generating a sampling signal from a read signal; a phase-comparator for detecting a phase difference from the sampling signal; a loop filter; and a voltage-controlled oscillator whose frequency is controlled by the phase difference as it is smoothed; there is provided a frequency divider; a clock extraction circuit for extracting a clock timing from the training signal as it is equalized partially-response signal; and a phase-comparator for finding a phase difference from an output of the frequency divider and an output of the clock extraction circuit, and the phase-comparator is connected to the loop filter during reproduction of the preamble portion of the data and the phase-comparator is connected to the loop filter during reproduction of a data portion of the data by the switching of a change-over switch. As a result, hangup is prevented and an accurate clock timing in the clock generator.