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:
Jan. 28, 1992
Filed:
Oct. 24, 1990
Kazuo Noda, Yokohama, JP;
Eiichi Nakamura, Sagamihara, JP;
Nippon Conlux Co., Ltd., Tokyo, JP;
Abstract
The present invention relates to an optical head for recording and playing back optical information, the optical head comprising an illumination system which shines three beams of light comprising 0-dimensional diffraction light, +1-dimensional diffraction light, and -1-dimensional diffraction light onto an optical information recording medium, and a photoreceiver system which receives three beams of reflected light from the recording medium; the photoreceiver system being provided with an edge mirror whereby, of the three beams of reflected light from the recording medium, approximately one half of the 0-dimensional diffraction light and all of the +1-dimensional diffraction light is received by a first photoreceiver diode, without being affected by the edge mirror, and the remaining approximately one half of the 0-dimensional diffraction light and all of the -1-dimensional diffraction light is reflected by the edge mirror and is received by a second photoreceiver diode; wherein a focusing control signal, a tracking control signal, and an information signal are obtained from an output from the first photoreceiver diode or the second photoreceiver diode, or from combined outputs from the first photoreceiver diode and the second photoreceiver diode.