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. 17, 2003
Filed:
May. 04, 2001
Mitsubishi Chemical Corporation, Tokyo, JP;
Abstract
To provide a rewritable compact disk having a rewritable area interchangeable with a CD-RW, that is, a RAM area ( ), and an area available only for retrieving, that is, a ROM area ( ), on the same disk surface, a phase-change recording layer is formed in each of the RAM area and the ROM area, with a wobble groove being made in the RAM area, irradiation is carried out with recording light so that an amorphous mark is formed to record information and information is recorded in the form of a pre-pit string ( ) in the ROM area, and further when measured using a wavelength of 770 to 790 nm and an optical pickup whose objective lens numerical aperture is 0.49 to 0.51, a ratio |I −I |/|I −I | of values of push pull signals before and after recording in the RAM area is set to be in a range from 1.05 to 2.0, or a ratio |I −I | /|I −I | of a value of a push pull signal after recording in the RAM area to a value of a push pull signal in the ROM area is set to be in a range from 0.78 to 1.3.