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:
Feb. 21, 1995
Filed:
Jan. 22, 1991
Yukio Kurata, Tenri, JP;
Hiroshi Ogata, Higashihiroshima, JP;
Hikaru Nishihara, Higashihiroshima, JP;
Mitsuharu Tomura, Higashihiroshima, JP;
Shigeki Tsuji, Higashihiroshima, JP;
Sharp Kabushiki Kaisha, Osaka, JP;
Abstract
An optical pickup apparatus for optically reading the data stored in a flat information carrier disc in the form of tiny pits. The pickup apparatus directs a beam of light from a light source to the disc surface. The impinging beam is modulated by the data pits and reflected back to a photodetector. A novel optical grating assembly is disposed between the light source and the information disc, and includes a diffraction grating for the light beam from the source and a holographic grating for directing part of the light beam reflected by the disc to the photodetector. The diffraction and holographic gratings are formed integral with each other into the grating assembly.