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:
May. 11, 1999
Filed:
Nov. 04, 1997
Kiyoshi Tateishi, Saitama-ken, JP;
Kazuo Takahashi, Saitama-ken, JP;
Pioneer Electronic Corporation, Tokyo-to, JP;
Abstract
An apparatus for reproducing record information of a multiple-layered optical disc is provided with: an optical pickup having a light source for emitting a reading light, an objective lens for condensing the emitted reading light onto one of the information record layers, a focus actuator for moving the objective lens in a focus direction, and a light-detection device for detecting the reflected reading light and outputting a light detection signal; a focus error generation device for generating a focus error signal; an acceleration/deceleration signal generator for generating and outputting to the focus actuator an acceleration signal to accelerate the objective lens in the focus direction and a deceleration signal to decelerate the objective lens in the focus direction; an inter-layer distance measurement device for measuring an interlayer distance between the information record layers of the multiple-layered optical disc; and a controller for measuring a time duration since the acceleration signal is generated until the focus error signal reaches a predetermined threshold level, and for controlling the acceleration/deceleration signal generator to set a magnitude of the deceleration signal on the basis of the measured inter-layer distance and the measured time duration.