Patent ID: 7961564
Filing Date: 2011-06-14
Classification: G11B

Abstract:
1. An information recording medium comprising: a substrate having a microscopic pattern, having a continuous shape of approximately parallel grooves formed with alternating groove and land sections; a recording layer formed on the microscopic pattern; a light transmission layer formed on the recording layer, wherein the microscopic pattern is formed so as to satisfy a relation of P<λ/NA and a thickness of the light transmission layer is within a range of 0.07 to 0.12 mm, wherein P is a pitch of the groove section or the land section, λ is a wavelength of reproducing light beam and NA is a numerical aperture of an objective lens; and wherein a wavelength λ of the reproducing light beam is within a range of 350 nm to 450 nm and a numerical aperture NA of the objective lens is within a range of 0.75 to 0.9, and wherein the land section is wobbled in the radial direction and having a wobbled shape corresponding to a signal to be recorded on the land section resulting from the modulation of a phase modulated wave that is further modulated by a single frequency wave, the single frequency wave having a frequency of integral multiples or one over integral multiples of a frequency of the phase modulated wave, and wherein the frequency of the single frequency wave is different from that of the phase modulated wave, and wherein the recording layer is formed by a phase change material, and further wherein the phase change material is any one of Ge—Sb—Te system, Ag—In—Sb—Te system, Cu—Al—Sb—Te system and Ag—Al—Sb—Te system.