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. 28, 2010
Filed:
Nov. 13, 2006
Takayoshi Hiraga, Kanagawa-ken, JP;
Takahiro Kaneko, Kanagawa-ken, JP;
Minoru Ohyama, Kanagawa-ken, JP;
Takayoshi Hiraga, Kanagawa-ken, JP;
Takahiro Kaneko, Kanagawa-ken, JP;
Minoru Ohyama, Kanagawa-ken, JP;
Victor Company of Japan, Limited, Yokohama-shi, Kanagawa-ken, JP;
Abstract
In a photo pickup device, an incident areafor a reflection light of a light spot is divided into four areasby parting linesmaking axial-symmetrical angles with a direction Y of a projected track on an optical disc. In these areas, the so-divided areasare formed so as to diffract the light in one or more directions in a range of 90 degrees±20 degrees to the direction Y and impress misalignment on each diffraction light. In each diffraction light, two focal lines produced due to the astigmatism make approx. 45 degrees with the direction Y of the projected track. Further, the divided areasare characterized by diffracting the light in one or more directions in a range of 90 degrees±20 degrees to the direction Y.