Optical disk, method for producing the same, and apparatus for producing the same

Abstract

An optical disk of the present invention includes a first substrate having a signal area on a principal plane and a central hole, and a second substrate that is transparent and attached to the first substrate. The second substrate is thinner than the first substrate, and has a central hole whose diameter is larger than that of the first substrate. The first substrate and the second substrate are attached to each other with radiation curable resin (adhesive member) disposed therebetween so as to extend at least from an inner peripheral edge of the second substrate to an outer peripheral edge thereof.

1 - 40 . (canceled)  
     
     
         41 . An optical disk comprising a first substrate having a signal area on a principal plane and a second substrate that is transparent and attached to the first substrate, 
 wherein the first substrate and the second substrate are attached to each other with an adhesive member disposed therebetween, and    the first substrate has a convex portion formed on the principal plane side, the height of the convex portion being larger than the sum of thickness of the second substrate and the thickness of the adhesive member:    
     
     
         42 . The optical disk according the  claim 41 , wherein the height of the convex portion in a range from 0.05 mm to 0.5 mm.  
     
     
         43 . The optical disk according to  claim 41 , wherein the first substrate has a central hole A, and the convex portion is formed in a circular shape so as to surround the central hole A.  
     
     
         44 . The optical disk according to  claim 43 , wherein the second substrate has a central hole B whose diameter is larger than that of the central hole A, the adhesive member is disposed so as to extend at least from an inner peripheral edge of the second substrate to an outer peripheral edge thereof, and an outer diameter of the convex portion is equal to or smaller than a diameter of the central hole B.  
     
     
         45 . The optical disk according to  claim 41 , wherein a thickness of the second substrate is in a range of 0.03 mm to 0.3 mm.  
     
     
         46 . The optical disk according to  claim 41 , wherein the signal area of the first substrate is provided with a plurality of signal recording layers.  
     
     
         47 . The optical disk according to  claim 41 , wherein the adhesive member is radiation curable resin.  
     
     
         48 . The optical disk according to  claim 44 , wherein the central hole B is larger than a clamp area of the optical disk.  
     
     
         49 . The optical disk according to  claim 48 , wherein the adhesive member is disposed on an outer peripheral side of a clamp area or disposed so as to cover the entire clamp area.  
     
     
         50 . The optical disk according to  claim 48 , wherein a thickness of a clamp area portion of the first substrate is in a range of 1.1 mm to 1.3 mm.  
     
     
         51 . The optical disk according to  claim 41 , wherein an average thickness of the adhesive member is in a range of 0.5 μm to 30 μm.  
     
     
         52 . The optical disk according to  claim 41 , wherein the optical disk is adapted for reproduction of information by application of a laser having a wavelength of 450 nm or less.  
     
     
         53 . An optical disk comprising: 
 a substrate having a signal area on a principal plane and a central hole;    a transplant layer provided in a first region of the principal plane, the first region including the signal area; and    a convex portion provided at a second region of the principal plane so as to surround the central hole, the second region being located between a peripheral edge of the center hole and an inner peripheral edge of the first region;    wherein the top of the convex portion projects from the surface of the transplant layer.    
     
     
         54 . The optical disk according to  claim 53 , wherein the transparent layer is constructed with a second substrate and an adhesive member for attaching the both substrate to each other.  
     
     
         55 . The optical disk according to  claim 53 , wherein a height of the convex portion from the principal plane is larger than the thickness of the transplant layer.  
     
     
         56 . The optical disk according to  claim 53 , wherein the convex portion is formed integrally with the substrate.  
     
     
         57 . The optical disk according to  claim 56 , wherein the substrate and the convex portion are made from the same material.  
     
     
         58 . The optical disk according to  claim 53 , wherein the second region is distant from the inner edge of the first region.