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. 29, 2011
Filed:
Jun. 12, 2008
Nobuyoshi Kobayashi, Kanagawa, JP;
Nobuyoshi Kobayashi, Kanagawa, JP;
Sony Corporation, Tokyo, JP;
Abstract
A tracking error signal detection device employing a differential phase detection method includes first and second differentiators which remove direct current components in first and second signal groups in which a phase difference between the first and second signal groups changes in accordance with a tracking error signal, and which differentiate the first and second signal groups, first and second analog/digital converters which sample and quantize signals output from the first and second differentiators, respectively, a Hilbert transformer performing a 90-degree phase shift on one of signals output from the first and second analog/digital converters, a delay circuit delaying one of the signals output from the second and first analog/digital converters by an amount of delay equal to that caused by the Hilbert transformer, and a phase comparator calculating a phase difference between a signal output from the Hilbert transformer and a signal output from the delay circuit.