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:
Sep. 26, 1995
Filed:
Aug. 19, 1993
Teruo Fujita, Nagaokakyo, JP;
Morihiro Karaki, Nagaokakyo, JP;
Mitsuru Irie, Nagaokakyo, JP;
Kazuhiko Nakane, Amagasaki, JP;
Mitsubishi Denki Kabushiki Kaisha, Tokyo, JP;
Abstract
A focus error detecting device includes a reflected beam splitter and at least two two-division photodetectors. The reflected beam splitter includes a diffraction grating part and a non-diffraction grating part separated by a line dividing a reflected beam. The dividing line projects to a line orthogonal to a guide groove on the information recording medium. The diffraction grating part produces a first split beam, and non-diffraction grating part produces a second split beam. Each two-division photodetector receives one of the first and second split beams incident and their light receiving sections, and produces a signal for effecting focus control.