Optical information recording medium

Abstract

An optical information recording medium including a substrate in which at least one of a groove and a pit is formed; a recording layer located overlying the substrate and including a dye; and a reflection layer located overlying the recording layer, wherein the optical information recording medium has an absorbance curve with an absorbance L of from 10 to 40% against light having a wavelength λ of from 645 nm to 670 nm, a ratio (Lmax/Lmin) of a maximum absorbance Lmax of the absorbance curve to a minimum absorbance Lmin of from 1.0 to 2.0 at the wavelength range of from 645 nm to 670 nm, and a reflectance of from 45 to 85% against the light having a wavelength λ of from 645 nm to 670 nm.

What is claimed is:  
     
         1 . An optical information recording medium comprising: 
 a substrate in which at least one of a groove and a pit is formed;    a recording layer located overlying the substrate and including at least one dye; and    a reflection layer located overlying the recording layer,    wherein the optical information recording medium has an absorbance curve with an absorbance L of from 10 to 40% against light having a wavelength λ of from 645 nm to 670 nm, a ratio (Lmax/Lmin) of a maximum absorbance Lmax of the absorbance curve to a minimum absorbance Lmin of from 1.0 to 2.0 at the wavelength range of from 645 nm to 670 nm, and a reflectance of from 45 to 85% against the light having a wavelength λ of from 645 nm to 670 nm.    
     
     
         2 . The optical information recording medium according to  claim 1 , wherein the recording layer comprises plural dyes each having an absorbance curve, and wherein slopes dL/dλ of the respective absorbance curves of the plural dyes are different.  
     
     
         3 . The optical information recording medium according to  claim 2 , wherein at least one of the slopes is positive and at least one of the slopes is negative at the wavelength range of from 645 nm to 670 nm.  
     
     
         4 . The optical information recording medium according to  claim 2 , wherein the plural dyes comprise a first dye compound (α) and a second dye compound (β) and wherein the absorption curve of the first dye compound (α) has a maximum absorbance at a wavelength of from 550 nm to 650 nm, and the absorbance curve of the second dye compound (β) has a maximum absorbance at a wavelength of from 650 nm to 750 nm.  
     
     
         5 . The optical information recording medium according to  claim 4 , wherein a molar ratio (β/α) of the second dye compound (β) to the first dye compound (α) is from 0.005 to 0.2.  
     
     
         6 . The optical information recording medium according to  claim 4 , wherein the first dye compound (α) and the second dye compound (β) have thermal decomposition temperatures Tα and Tβ, respectively, and wherein each of the thermal decomposition temperatures Tα and Tβ is not higher than 400° C. and the difference therebetween is not greater than 100° C.  
     
     
         7 . The optical information recording medium according to  claim 4 , wherein the first dye compound (α) is a formazan chelate compound having the following formula (I):  
       
         
           
           
               
               
           
         
       
       wherein Z represents a group which forms a polyheterocyclic ring while sharing bond with a carbon atom and a nitrogen atom, wherein the polyheterocyclic ring optionally has a substituent selected from the group consisting of alkyl groups, alkoxy groups, thioalkoxy groups, substituted amino groups, aryl groups, aryloxy groups, anilino groups and keto groups; A represents an alkyl group, an aralkyl group, an aryl group or a cyclohexyl group, which are optionally substituted with a group selected from the group consisting of alkyl groups, alkoxy groups, halogen atoms, keto groups, carboxyl groups, carboxyester groups, nitrile groups and nitro groups; B represents an aryl group, wherein the aryl group is optionally substituted with a group selected from the group consisting of alkyl groups, alkoxy groups, halogen atoms, carboxyl groups, carboxyester groups, nitrile groups and nitro groups; M represents a divalent metal atom; and n represents the number of the formazan ligand.  
     
     
         8 . The optical information recording medium according to  claim 1 , a groove being formed on the substrate at a track pitch of from 0.73 to 0.75 μm, wherein the groove has a depth and a width of from 1450 to 1650 Å and from 0.21 to 0.31 μm, respectively.  
     
     
         9 . The optical information recording medium according to  claim 1 , a groove being formed on the substrate, wherein the groove is wobbled at substantially a constant frequency.