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:
Oct. 05, 1993
Filed:
Jun. 17, 1992
Yoshihiro Utsumi, Tokorozawa, JP;
Yoshiyuki Kakuta, Tokorozawa, JP;
Pioneer Electronic Corporation, Tokyo, JP;
Abstract
In an apparatus for detecting an abnormality of an optical system in a reproducing and recording apparatus of an optical recording medium and executing a driving control of a laser diode, detection of abnormality is performed with the optical system set into a de-focusing state. The apparatus has control device for comparing a level of a first detection signal having the level according to the level of first light beam which is led to the optical recording medium and a level of a second detection signal having the level of the second light beam, thereby controlling a driving current. The control device turns off a loop switch of a focusing servo loop of an objective lens, thereby setting the lens into a de-focusing mode, compares the levels of the first and second detection signals after the de-focusing state of the lens by the actuator is obtained, to discriminates whether a ratio of those levels lies within a predetermined range or not; and shuts off the driving current when it is determined that the ratio is out of the predetermined range.