Optical recording medium and its manufacturing method
AssigneeSony Corporation
InventorsKazuya Hayashibe, Katsuya Ohwada
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Abstract
A multi-layered film made of sequentially stacked first dielectric layer, recording layer, record-assist layer, second dielectric layer and first reflection layer on a disc substrate having a concavo-convex structure at least on one surface thereof. An ultraviolet-setting resin layer is formed to cover the multi-layered film. The record-assist layer is controlled in thickness to satisfy the relation d/4<a<3d, or more preferably the relation d/2≦a≦2d, between the thickness d of the recording layer and the thickness a of the record-assist layer. The stacking order of the multi-layered film may be opposite. In this case, a light-transmitting sheet is provided to cover the multi-layered film via a bonding layer.
Claims39
An optical recording medium comprising:
- a disc substrate having formed a concavo-convex structure formed at least on one surface thereof;
- and
- a multi-layered film made by stacking at least a recording layer capable of recording information signals by irradiation of a laser beam and a record-assist layer adjacent to the recording layer on the surface of the disc substrate having the concavo-convex structure,
- wherein,
- d/4<a<3d is satisfied where d is the thickness of the recording layer and a is the thickness of the auxiliary recording layer, and
- in a portion of the disc substrate having the concavo-convex structure, width Dg of a level difference of a portion nearer to the injection side of the laser beam and width D1 of a level difference of a portion remoter from the injection side of the laser beam satisfy the ratio of 0.5≦D1/Dg≦2.0.
A method of manufacturing an optical recording medium, which forms a multi-layered film made by stacking at least a recording layer capable of recording information signals by irradiation of a laser beam and a record-assist layer adjacent to the recording layer on the surface of the disc substrate having the concavo-convex structure, comprising:
- adjusting the thickness of the record-assist layer to satisfy d/4<a<3d where d is the thickness of the recording layer and a is the thickness of the record-assist layer.
- wherein,
- in a portion of the disc substrate having the concavo-convex structure, width Dg of a level difference of a portion nearer to the injection side of the laser beam and width D1 of a level difference of a portion remoter from the injection side of the laser beam satisfy the ratio of 0.5 D1/Dg≦2.0.
Dependencies are inferred from the claim text.