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AssigneeHitachi, Ltd.
InventorsYumiko Anzai, Motoyasu Terao, Tetsuya Nishida, Mokoto Miyamoto
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An optical disk for recording/reproducing information tends to have fine irregularities on its substrate surface that cause an increase in noise, which irregularities are formed during the process of forming the recording layer, which is capable of changing physically or chemically in response to irradiation of laser light. This problem can deteriorate the recording and reproduction characteristics and bring about a defect on a life test or on the storage ability on the disk. To solve this problem, a method of manufacturing an optical disk having a pits-and-lands pattern employs an organic material which is modified by ultraviolet light irradiation. The transmission of the substrate is not more than 50% at one wavelength in a wavelength region from 300 to 375 nm. As a result of the ultraviolet ray irradiation, the surface of an optical disk substrate is smoothed so as to effect a reduction of the substrate noise and an improvement of the recording and reproduction characteristics. Moreover, adhesiveness between the substrate and another layer formed thereon is improved, so that the number of generated defects is reduced.
A method of manufacturing an optical disk substrate, comprising a process of reforming the surface of polycarbonate by flowing an oxygen containing gas on the optical disk substrate composed of a plastic material containing oxygen atoms on the main organic atomic-chain thereof and having irregularities on its surface and by irradiating the optical disk substrate with ultraviolet light so that ozone generated on the optical disk substrate becomes not more than 0.1 ppm.
An apparatus of manufacturing an optical disk substrate that conducts surface processing of the optical disk substrate, comprising:
An apparatus of manufacturing an optical disk substrate that conducts surface processing on an optical disk substrate, comprising:
An apparatus of manufacturing an optical disk substrate that conducts surface processing of the optical disk substrate, comprising:
An optical disk substrate, the substrate being made of a plastic material, having the transmittance not more than 50 % at one wavelength in a wavelength region from 300 to 375 nm.
An optical disk substrate made of a plastic material, wherein the polystyrene equivalent weight-average molecular weight of the substrate in the thickness range from the surface thereof to the depth of 20 μm is smaller than that of the substrate excluding the surface parts from the surface to the depth of 100 μm by 4 to 22%.
A method of manufacturing an optical disk substrate, comprising a process of reforming the surface of polycarbonate by flowing an oxygen containing gas on the optical disk substrate composed of a plastic material containing oxygen atoms on the main organic atomic-chain thereof and having irregularities on its surface and by irradiating ultraviolet light of a wavelength of approximately 254 nm on the optical disk substrate while shielding ultraviolet light of a wavelength of approximately 185 nm.
An apparatus of manufacturing an optical disk substrate that conducts the surface processing of the optical disk substrate, comprising:
An apparatus of manufacturing an optical disk substrate that conducts the surface processing of the optical disk substrate, comprising:
An apparatus of manufacturing an optical disk substrate that conducts the surface processing of the optical disk substrate, comprising:
An apparatus of manufacturing an optical disk substrate that conducts the surface processing of the optical disk substrate, comprising:
Dependencies are inferred from the claim text.