Optical recording medium having auxiliary information and reference clock

Abstract

An information recording medium is composed of a substrate having a microscopic pattern constituted by a continuous substrate of grooves formed with a groove portion and a land portion alternately, a recording layer, and a light transmitting layer. The microscopic pattern is formed with satisfying a relation of P≦λ/NA, wherein P is a pitch of the land portion or the groove portion, λ is a wavelength of reproducing light, and NA is a numerical aperture of an objective lens. The land portion is formed with wobbling so as to be parallel with each other for both sidewalls of the land portion. Auxiliary information and a reference clock is recorded alternately. Information is recorded in the recording layer corresponding to a land portion by either one change of reflectivity difference and refractive index difference in the recording layer.

1 . An information recording medium at least comprising:
 a substrate having a first microscopic pattern corresponding to a recording and reproducing area and a second microscopic pattern corresponding to a read-only area, each microscopic pattern including a continuous substrate of grooves formed with a groove portion and a land portion alternately;   a recording layer formed on each microscopic pattern for recording information; and   a light transmitting layer formed on the recording layer,   wherein each microscopic pattern is formed with satisfying a relation of P≦λ/NA, wherein P is a pitch of the land portion or the groove portion, lambda is a wavelength of reproducing light for reproducing the recording layer, and NA is a numerical aperture of an objective lens, and   wherein the land portion is formed with wobbling so as to be parallel with each other for both sidewalls of the land portion, and   wherein auxiliary information based on data used supplementally when recording the information and a reference clock based on a clock used for controlling a recording speed when recording the information, are recorded alternately and continuously, and   wherein the auxiliary information is recorded by a frequency-shift keying modulation wave having two different frequencies, and   wherein the reference clock is composed of a single frequency, and   wherein the single frequency coincides with either one frequency of the two different frequencies, and   wherein information is recorded in the read-only area by a frequency-shift keying modulation wave having two different frequencies, and   further wherein the read-only area is allocated in an inner circumference side of the recording and reproducing area in the information recording medium and connected with the recording and reproducing area at one point.   
     
     
         2 . A reproducing apparatus for reproducing a recording layer of an information recording medium comprising:
 a substrate having a first microscopic pattern corresponding to a recording and reproducing area and a second microscopic pattern corresponding to a read-only area, each microscopic pattern including a continuous substrate of grooves formed with a groove portion and a land portion alternately;   the recording layer formed on each microscopic pattern for recording information; and   a light transmitting layer formed on the recording layer,   wherein each microscopic pattern is formed with satisfying a relation of P≦λ/NA, wherein P is a pitch of the land portion or the groove portion, lambda is a wavelength of reproducing light for reproducing the recording layer, and NA is a numerical aperture of an objective lens, and   wherein the land portion is formed with wobbling so as to be parallel with each other for both sidewalls of the land portion, and   wherein auxiliary information, based on data used supplementally when recording the information and a reference clock based on a clock used for controlling a recording speed when recording the information, are recorded alternately and continuously, and   wherein the auxiliary information is recorded by a frequency-shift keying modulation wave having two different frequencies, and   wherein the reference clock is composed of a single frequency, and   wherein the single frequency coincides with either one frequency of the two different frequencies, and   wherein information is recorded in the read-only area by a frequency-shift keying modulation wave having two different frequencies, and   further wherein the read-only area is allocated in an inner circumference side of the recording and reproducing area in the information recording medium and connected with the recording and reproducing area at one point,   the reproducing apparatus comprising:   a light emitting element for emitting reproducing light having a wavelength λ of 350 nm to 450 nm and a noise of less than RIN (Relative Intensity Noise) −125 dB/Hz;   a reproducing means equipped with an objective lens having a numerical aperture NA of 0.75 to 0.9;   a control means for controlling the reproducing means to irradiate the reproducing light only on the land portion for reproducing,   wherein the reproducing means reproduces both the recording and reproducing area and the read-only area.