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:
Dec. 19, 1989
Filed:
Jul. 02, 1987
Masataka Itoh, Tokyo, JP;
NEC Corporation, Tokyo, JP;
Abstract
An improved optical head comprises such a means as a prism for separating a plurality of light beams deflected from the light path between a plurality of light sources and record medium to pass at least one of the plurality of light beams through one of reflecting planes of the means and to reflect the remaining light beams of the plurality of light beams thereon for the reason why each light axis of the plurality of light beams has a slight slant to others, and the reflecting plane is shaped to have an angle such that the incidence angle of the at least oen of the plurality of light beams is smaller than the critical angle of the means, while the remaining light beams of the plurality of light beams are larger in the incidence angles than the critical angle of the means. The at least one of the plurality of light beams is detected to crrect focusing and tracking errors.