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. 04, 2004
Filed:
Oct. 10, 2000
Shinichiro Abe, Kawagoe, JP;
Takayuki Iijima, Kawagoe, JP;
Pioneer Corporation, Tokyo-to, JP;
Abstract
A focus servo control is performed by changing a condition of a focus servo loop from an open condition to a close condition in correspondence with a level of a reflection light signal, which is obtained as a reflection light of a light beam reflected from an information record medium is detected by a light receiving element such as an optical pickup. A focus servo controlling apparatus is provided with a disturbance level detecting device such as a servo control circuit for detecting a level of a disturbance light signal, which is obtained as a disturbance light other than the reflection light is received by the light receiving element; and a controlling device such as a system controller for setting a level, which is larger than the level of the disturbance light signal detected by the disturbance level detecting device, as a threshold level and for changing the condition of the focus servo loop from the open condition to the close condition on the basis of a timing when the level of the reflection light signal becomes equal to or larger than the set threshold level.