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:
Dec. 24, 1985
Filed:
Dec. 21, 1982
Shohei Yamazaki, Hamamatsu, JP;
Nippon Gakki Seizo Kabushiki Kaisha, Hamamatsu, JP;
Abstract
An automatic focusing device in an optical type data reproducing apparatus is capable of restoring an objective lens to a position in which a servo controlling system can perform a normal servo control, when the servo controlling system has entered a divergent state. In the device, a photodetector produces a detection signal corresponding to a relative distance between the objective lens and a disk and, in response to this detection signal, the servo controlling system automatically controls the relative distance between the objective lens and the disk so as to form a focal point on a signal plane of the disk. If the objective lens has entered a region in which the servo controlling system has deviated from a converging range and entered divergence, this divergent state is detected in response to the level of an integrated signal of the detection signal from the photodetector and thereupon the objective lens is forcibly moved to a position in which the servo controlling system can perform a normal servo control.