Patent ID: 7318232

Claim:
An optical disc for recording information signals, the optical disc comprising: a first disc substrate made of synthetic resin and provided with an information signal recording layer; and a second disc substrate made of synthetic resin and provided with an information signal recording layer; the first disc substrate having a raised section formed at the center of the substrate main body thereof and raised from one of the surfaces of the substrate main body with a first center hole bored through the center thereof, the front end surface of the raised section operating as reference surface when mounted on a rotary drive mechanism, and a plate receiving recess formed on the other surface of the substrate main body thereof in a region corresponding to the raised section and provided with a magnetically attractable clamping plate; the second disc substrate having a second center hole bored through the center thereof and a projecting section projecting from the second center hole toward the one of the surfaces of the substrate main body thereof; the second disc substrate being bonded to the other surface of the first disc substrate with the projecting section entering into the plate receiving recess of the first disc substrate; the projecting section arranged on the second disc substrate being so formed as to enter into the plate receiving recess, keeping a gap between the front end thereof and the plate receiving recess, at the time of bonding the second disc substrate to the first disc substrate; and the clamping plate arranged in the plate receiving recess formed on the first disc substrate being supported by the projecting section arranged on the second disc substrate.