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:
Jul. 25, 2006
Filed:
Mar. 28, 2002
Hiroyuki Arioka, Tokyo, JP;
Syuji Tsukamoto, Tokyo, JP;
Takashi Horai, Tokyo, JP;
Shirou Ootsuki, Tokyo, JP;
Hiroyuki Arioka, Tokyo, JP;
Syuji Tsukamoto, Tokyo, JP;
Takashi Horai, Tokyo, JP;
Shirou Ootsuki, Tokyo, JP;
TDK Corporation, Tokyo, JP;
Abstract
On a recording layer () of a disc-shaped optical recording medium (), a plurality of virtual recording cells () are assumed contiguously in a spiral or concentric fashion in a groove (). The irradiation time of the laser beam is modulated in five stages or more for each of the virtual recording cells () in response to information to be recorded, thereby forming recording marks (A toG) of different sizes in five stages or more. The optical reflectivity of the virtual recording cell () is modulated in multi-stages to thereby vary the reflection level of a reading laser beam for reading operations in five stages or more. The length of the virtual recording cells () in the rotational direction of the disc is set to be equal to that of an arc having the same center angle with respect to the center of the disc.