Patent ID: 7224665

Claim:
An optical recording medium constructed in a manner such that an information signal portion is provided on one principal plane of a substrate and, by irradiating a laser beam to said information signal portion of said substrate from a side where said information signal portion exists, an information signal can be recorded and/or reproduced to/from said information signal portion, wherein a clamp reference surface exists on the principal plane of said substrate where said information signal portion has been provided, at least said clamp reference surface is constructed by a flat surface, and a thickness of said substrate in a clamping area which is specified by said clamp reference surface is larger than that of said substrate in a forming area of at least said information signal portion, wherein a light transmitting layer which can transmit at least said laser beam is provided on the principal plane of said substrate where said information signal portion has been provided, said light transmitting layer is constructed by a light transmitting sheet which can transmit at least said laser beam and an adhesive layer which can transmit at least said laser beam, and said light transmitting sheet is provided via said adhesive layer onto the principal plane of said substrate where said information signal portion has been provided, said adhesive layer is made of a pressure sensitive adhesive agent, wherein a groove is formed as a depression into said principal plane of said substrate in an area between said information signal portion and said clamp reference surface, the groove being formed in the area other than the forming area of said information signal portion and an area other than said clamp reference surface, wherein said light transmitting layer has a plane ring shape having a second opening in a center portion, and a diameter of said second opening is larger than an outer peripheral diameter of said groove, and wherein said light transmitting layer comprises a protective film formed on a surface of said light transmitting sheet opposite said adhesive layer, said protective film comprising an ultraviolet hardening resin and a silicon oil lubricating additive and effecting a high surface lubricating performance, said protective film having been adhered to said light transmitting sheet by a roll coating method prior to said light transmitting layer being adhered to said substrate.