Sanyo Electric Co., Ltd.

Sadao Sakamoto

Masahiro Higuchi

Yoshiharu Uchihara

The method of manufacturing an optical disc related to the invention first forms warp prevention layer on one surface or the other surface of the disc substrate where information is recorded on one surface, and then, recording film covering the surface opposite from the surface having warp prevention layer or beam reflection film covering the information-recorded surface, and finally protection layer covering either the beam reflection film or the recording film, in this order. Thus the optical disc related to this invention can prevent damage and dust from incurring and adhering to the other surface of the disc substrate when forming these films on one surface so that the warp prevention layer can be perfectly level by suppressing swell of the layer itself. Since the warp prevention layer is formed on one surface before forming those films mentioned above on the other surface, the one surface maintains satisfactory wetness, and as a result, foam is rarely generated between the warp prevention layer and the disc substrate. Furthermore, the method of manufacturing an optical disc related to the invention introduces a system which measures the warp of the disc substrate coated with warp prevention layer before coating protection film, and then properly adjusts the thickness of the protection film to a specific thickness enough to fully cancel the warp. This effectively minimizes warping of the disc substrate itself.

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Ogaki, Japan

Sadao Sakamoto