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:
May. 18, 1999
Filed:
Feb. 11, 1997
Jau-Jiu Ju, Chutung Town, TW;
Tsung-Ming Yang, Chilung, TW;
Shin-Ter Tsai, Taipei, TW;
Pei-Yih Liu, ChiChou Hsiang, TW;
Abstract
A grating pattern for a bifocal optical pick-up head assembly of an optical compact disc drive device is disclosed. The device is capable of accessing data on the surface of compact discs arranged in either the DVD or the CD formats. The optical head assembly has an optical system that includes a grating plate and an objective, wherein the grating plate contains the grating pattern, and the objective focuses a light beam onto the data surface of the accessed compact disc. The grating pattern includes a first region that contains no grating and a second region that contains grating. The first region substantially surrounds the second region. The light beam that passes through the first region of the grating pattern is incident to the cross-sectional aperture of the objective for the DVD format of the accessed optical disk. The light beam that passes through the second region of the grating pattern is incident to the cross-sectional aperture of the objective for the CD format of the accessed optical disk.