Patent ID: 8142981
Filing Date: 2012-03-27
Classification: G11B

Abstract:
1. An information storage medium comprising: a light reflective layer; a recording layer formed on the light reflective layer, the recording layer including an unrecorded portion; and a transparent layer formed on or above the recording layer, wherein light is incident to the recording layer through the transparent layer and is reflected by the light reflective layer, and the recording layer has properties of a maximum absorption wavelength at which a light absorbance in the unrecorded portion is maximum being longer than 405 nm, a light absorbance in the unrecorded portion at a wavelength of 355 nm being not smaller than 40% of the light absorbance at the maximum absorption wavelength, information being recordable onto the recording layer by light at a wavelength of 405 nm, and an intensity of the light reflected by the light reflective layer and transmitted through a recorded portion of the recording layer being higher than an intensity of the light reflected by the light reflective layer and transmitted through the unrecorded portion, the recorded portion forms marks, a whole or a part of one of the marks is to be formed in data blocks, a guard area is configured to be arranged between data blocks, and the guard area is configured to include a variable frequency oscillation area for synchronization of a reference clock for reproducing information.