JP2005071605A5 - - Google Patents

Claims (12)

An optical disc comprising a first substrate having a signal area on one main surface and a second substrate bonded to the one main surface side of the first substrate,
The thickness of the second substrate is smaller than the first substrate,
The first substrate and the second substrate are bonded together by an adhesive member disposed between the first substrate and the second substrate;
The first substrate includes a convex portion formed on the one main surface,
An optical disc, wherein a height of the convex portion from the one main surface is larger than a sum of a thickness of the second substrate and a thickness of the adhesive member. The optical disc according to claim 1, wherein a height of the convex portion from the one principal surface is 0.05 mm or more and 0.5 mm or less. The first substrate has a center hole A;
The optical disk according to claim 1, wherein the convex portion is formed in an annular shape so as to surround the center hole A. The second substrate has a center hole B having a diameter larger than that of the center hole A,
The adhesive member is disposed at least from the inner peripheral end to the outer peripheral end of the second substrate,
The optical disk according to claim 3, wherein an outer diameter of the convex portion is equal to or smaller than a diameter of the center hole B.   The optical disk according to any one of claims 1 to 4, wherein a thickness of the second substrate is in a range of 0.03 mm to 0.3 mm.   The optical disc according to claim 1, wherein a plurality of signal recording layers are formed in the signal area of the first substrate.   The optical disk according to claim 1, wherein the adhesive member is a radiation curable resin.   The optical disc according to claim 4, wherein the center hole B is larger than a clamp region.   The optical disk according to claim 8, wherein the adhesive member is disposed on the outer peripheral side of the clamp region, or is disposed so as to cover the entire clamp region.   The optical disk according to claim 8, wherein a thickness of the clamp region of the first substrate is 1.1 mm or greater and 1.3 mm or less.   The optical disc according to any one of claims 1 to 3, wherein an average thickness of the adhesive member is in a range of 0.5 to 30 µm. The optical disk according to any one of claims 1 to 3, wherein a wavelength of a laser irradiated for reproducing information is 450 nm or less.