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:
Jun. 04, 1996
Filed:
May. 17, 1995
Applicant:
Inventor:
Mark O Freeman, Hsinchu, TW;
Assignee:
Opto-Electronics & Systems Laboratories, Chutung Hsinchu, TW;
Primary Examiner:
Int. Cl.
CPC ...
G11B / ;
U.S. Cl.
CPC ...
369109 ; 369103 ; 369105 ; 369116 ; 369 4425 ; 2502015 ;
Abstract
A pickup head for use in optical disk systems such as compact disk players or CD-ROM computer memory includes a holographic optical element that has two decision regions that greatly simplify the design of the pickup head. The two decision regions diffract light that encounters the holographic optical element in two different directions, respectively. The amount of light power incident upon each decision region is utilized to determine a focus error signal and to interpret information stored on the compact or optical disk.