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:
Aug. 07, 2007
Filed:
Apr. 06, 2004
Hidenori Wada, Uji, JP;
Tomotada Kamei, Neyagawa, JP;
Sadao Mizuno, Ibaraki, JP;
Hideki Hayashi, Nara, JP;
Hidenori Wada, Uji, JP;
Tomotada Kamei, Neyagawa, JP;
Sadao Mizuno, Ibaraki, JP;
Hideki Hayashi, Nara, JP;
Matsushita Electric Industrial Co., Ltd., Osaka, JP;
Abstract
An optical head is provided with: an objective-lens-use opening that determines an aperture of the objective lens; a light-source light-quantity controlling opening that aperture-controls light that has been separated by the light separation device; a light detector that receives light that has been aperture-controlled by the light-source light-quantity controlling opening; and a light detector that receives light that has been reflected by the optical recording medium, and has an arrangement in which: the length of the optical light path from the spherical aberration correcting device to the objective-lens-use opening is made virtually the same as a length of the optical light path from the spherical aberration correcting device to the light-source light-quantity controlling opening, and the aperture of the light-source light-quantity controlling opening has virtually the same size as the aperture of the objective-lens-use opening. The objective of the present invention is to provide an optical head in which a signal outputted from the light quantity detection device is unchanged even when the spherical aberration correcting device is driven so that by using this signal, the quantity of light from the light source is set to an appropriate value.