Patent ID: 8238205
Filing Date: 2012-08-07
Classification: G11B

Abstract:
1. A reproducing apparatus comprising: a recording medium having (a) a substrate having a microscopic pattern, having a continuous shape of approximately parallel grooves formed with alternating groove and land sections; (b) a recording layer formed on the microscopic pattern; (c) 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, and 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 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 further wherein a refractive index of the light transmission layer is within a range of 1.45 to 1.7, the reproducing apparatus further comprising: (d) a pickup composed of a light emitting element having a wavelength of λ within a range of 350 to 450 nm and an objective lens having a numerical aperture of NA within a range of 0.75 to 0.9 for reading out reflected light from and recording on the information recording medium; (e) a motor for rotating the information recording medium; (f) servo means for controlling the drive of the pickup and the motor; (g) a turntable for supporting the information recording medium while rotating; (h) demodulator means for demodulating an information signal read out by the pickup, wherein the demodulator means is composed of a limit equalizer; (i) interface (I/F) means for transmitting a signal demodulated by the demodulator means externally; (j) auxiliary information demodulator for demodulating a differential signal outputted from the pickup; and (k) controlling means for controlling the entire reproducing apparatus.