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:
Aug. 13, 1991
Filed:
Mar. 02, 1989
Hitachi Maxell, Ltd., Osaka, JP;
Abstract
An optical information recording medium in which pre-pits longer than the diameter of a reproducing radiation spot and pre-pits shorter than the diameter of the reproducing radiation spot coexist, the width W of the pre-pit longer than the diameter of the reproducing radiation spot being formed with a value satisfying a relation of .PHI./4<W<.PHI./3, wherein .PHI. is the diameter of the reproducing radiation spot and a method of fabricating the optical information recording medium comprising setting a power of a radiation beam when a pre-pit shorter than the diameter of the reproducing radiation spot among a plurality of pre-pits to be formed for each sector is cut to a predetermined optimum value, setting a power of the radiation beam when the pre-pit longer than the diameter of the reproducing radiation spot is cut to a predetermined value smaller than the predetermined optimum value of the radiation beam power when the pre-pit shorter than the diameter of the reproducing radiation spot is cut, and performing the cutting of pre-pits while combining the radiation beam power at the predetermined optimum value when the pre-pit shorter than the diameter of the reproducing radiation spot is cut with the radiation beam power at the predetermined smaller value when the pre-pit longer than the diameter of the reproducing radiation spot is cut.