Information recording medium and disk apparatus using the medium

Abstract

According to one embodiment, an information recording medium has a plurality of recording layers, and records and reproduces information by using a semiconductor layer of 450 nm or less. When reproducing information, letting x be the frequency of repetitive recording of a shortest mark length and shortest space length of the information, the ratio of the value of a highest level to the value of a level at x/190 of a sum signal detected within the frequency range of x/3240 to x/190 is lower than 32 dB, or the ratio of the average value of the amplitudes of signals of repetitive recording of the shortest mark length and shortest space length to the value of the highest level within the frequency range of x/3240 to x/190 is higher than 10 dB.

1 . An information recording medium having a plurality of recording layers and to record and reproduce information by irradiating the recording layer with a semiconductor laser of not more than 450 nm,
 wherein when reproducing recorded information by detecting light reflected by the recording layer by using a light-detecting mechanism, letting x be a frequency of repetitive recording of a shortest mark length and shortest space length of the information, a ratio of a value of a highest level to a value of a level at x/190 of a sum signal detected by the light-detecting mechanism is less than 32 dB, within a frequency range represented by x/3240 to x/190.   
   
   
       2 . A medium according to  claim 1 , wherein at least one of said plurality of recording layers contains an organic dye material. 
   
   
       3 . An information recording medium having a plurality of recording layers and to record and reproduce information by using a semiconductor laser of not more than 450 nm,
 wherein when reproducing recorded information by detecting light reflected by the recording layer by using a light-detecting mechanism, letting x be a frequency of repetitive recording of a shortest mark length and shortest space length of the information, a ratio of an average value of amplitudes of signals of repetitive recording of the shortest mark length and the shortest space length to a value of a highest level of a sum signal detected by the light-detecting mechanism is higher than 10 dB, within a frequency range of x/3240 to x/190.   
   
   
       4 . A medium according to  claim 3 , wherein at least one of said plurality of recording layers contains an organic dye material. 
   
   
       5 . A medium according to  claim 3 , wherein a ratio of the value of the highest level to a value of a level at x/190 of the sum signal is less than 32 dB. 
   
   
       6 . An optical disk apparatus comprising:
 an emitting mechanism to emit a laser beam to an information recording medium having a plurality of recording layers and to record and reproduce information by irradiating the recording layer with a semiconductor laser of not more than 450 nm, wherein when reproducing recorded information by detecting light reflected by the recording layer by using a light-detecting mechanism, letting x be a frequency of repetitive recording of a shortest mark length and shortest space length of the information, a ratio of a value of a highest level to a value of a level at x/190 of a sum signal detected by the light-detecting mechanism is lower than 32 dB, within a frequency range represented by x/3240 to x/190;   a light-receiving mechanism to receive reflected light from the laser beam emitted by the emitting mechanism; and   a reproducing mechanism to reproduce recorded information on the basis of the reflected light received by the light-receiving mechanism.   
   
   
       7 . An apparatus according to  claim 6 , wherein at least one of said plurality of recording layers contains an organic dye material. 
   
   
       8 . An optical disk apparatus comprising:
 an emitting mechanism to emit a laser beam an information recording medium having a plurality of recording layers and to record and reproduce information by using a semiconductor laser of not more than 450 nm, wherein when reproducing recorded information by detecting light reflected by the recording layer by using a light-detecting mechanism, letting x be a frequency of repetitive recording of a shortest mark length and shortest space length of the information, a ratio of an average value of amplitudes of signals of repetitive recording of the shortest mark length and the shortest space length to a value of a highest level of a sum signal detected by the light-detecting mechanism is higher than 10 dB, within a frequency range of x/3240 to x/190;   a light-receiving mechanism to receive reflected light from the laser beam emitted by the emitting mechanism; and   a reproducing mechanism to reproduce recorded information on the basis of the reflected light received by the light-receiving mechanism.   
   
   
       9 . An apparatus according to  claim 8 , wherein at least one of said plurality of recording layers contains an organic dye material. 
   
   
       10 . An apparatus according to  claim 8 , wherein a ratio of the value of the highest level to a value of a level at x/190 of the sum signal is less than 32 dB.