Patent ID: 6154442
Filing Date: 2000-11-28
Classification: G11B

Abstract:
An optical information-recording medium that has at least two or more different information-recording surfaces each of which has separate information previously recorded thereon in the thickness direction of a light transmitting substrate and that allows reading of the information recorded on each information-recording surface of the two or more information-recording surfaces through said substrate by varying the focal position of a playback laser beam incident on and passing through said light transmitting substrate, said light transmitting substrate having first pits corresponding to first information on one surface thereof forming an information-recording surface comprising:a first reflecting layer formed on the information-recording surface of said light transmitting substrate;a transparent layer that is formed onto said first reflecting layer, wherein said transparent layer is formed from a thermoplastic resin sheet having a uniform thickness above at least 20 .mu.m in thickness and a second information-recording surface having second pits corresponding to second information, wherein said transparent layer is formed by cutting said thermoplastic resin sheet along the outer edge of said light transmitting substrate, and wherein said second pits are transferred to the surface of said thermoplastic resin sheet and the surface of said thermoplastic resin sheet is adhered to said first reflecting layer by melting the surface of said thermoplastic resin sheet, and said thermoplastic resin sheet is solidified by cooling after the surface thereof has been melted;a second reflecting layer formed on said second information-recording surface of said transparent layer; anda protective layer formed on said second reflecting layer.