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. 12, 1996
Filed:
Jul. 20, 1994
Junichi Takeda, Tokyo, JP;
Canon Kabushiki Kaisha, Tokyo, JP;
Abstract
An AGC system controls the amplitude of a reproduction signal read out from a recording medium at a predetermined level by adjusting the gain of an AGC amplifier. The AGC system includes a differentiator which differentiates the output signal of the AGC amplifier and then outputs a resultant differential signal. A rectifier rectifies the output differential signal. An operation unit compares the output signal of the rectifier with a predetermined reference value and outputs an error signal corresponding to the difference between them. The gain of the AGC amplifier is adjusted according to the error signal so that the output signal of the AGC amplifier and the output signal of the differentiator may be controlled at respective predetermined levels. The amplitude level of a reproduction signal can be maintained at a predetermined level regardless of the MTF characteristics of an optical system or other factors and a single AGC circuit can provide both reproduction signals which are suitable for both mark edge recording and mark position recording.