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:
Mar. 02, 2004
Filed:
Mar. 28, 2002
Hiroyuki Arioka, Tokyo, JP;
Syuji Tsukamoto, Tokyo, JP;
Takashi Horai, Tokyo, JP;
Shirou Ootsuki, Tokyo, JP;
TDK Corporation, Tokyo, JP;
Abstract
An optical recording medium ( ) is adapted such that information is recorded by forming recording marks on a recording layer ( ) that covers grooves ( ) of an optical transparent substrate ( ). In the recording layer ( ), contiguously defined along a feed direction S of irradiation are virtual recording cells ( ) which have a given unit length in the feed direction S of irradiation along the groove and a given unit width in the direction orthogonal thereto. In addition, the groove width W is set so that 0.20×(&lgr;/NA)<W<0.50×(&lgr;/NA), where &lgr; is the wavelength of a laser beam to be irradiated with and NA is the numerical aperture of the objective lens for the laser beam in a irradiation optical system. The irradiation time is set in five stages or more to radiate the laser beam, thereby making it possible to record information in multi-levels.