Optical disk and optical disk apparatus
AssigneeKabushiki Kaisha Toshiba
InventorYasuaki Ootera
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Abstract
There is provided an optical disk which adopts a PRML (Partial Response and Maximum Likelihood) method for reproduction of recorded information and whose shortest pit has a conical shape without a bottom surface. If the PRML method is adopted, since it is not necessary to assure a large amplitude of a reproduction waveform of the shortest pit, the pit may have a conical shape. The conical pit enables recording with the dense shortest pit even in a conventional original disk recorder and original disk exposure process, thereby increasing a recording density in a dividing direction.
Claims8
An optical disk having a plurality of pits indicative of information, comprising:
- the shortest pit has a conical shape and its depth is smaller than a depth of a pit other than the shortest pit.
An optical disk comprising a reflecting film formed on a molded substrate having pits indicative of information, the information being read from the reflecting film side by using a laser beam,
- a cross-sectional shape of the shortest pit is trapezoidal in the molded substrate, and it is triangular on a surface of the reflecting film.
A method of manufacturing an optical disk by forming a reflecting film on a molded substrate having pits indicative of information formed thereto,
- the shortest pit cross-sectional shape before forming the reflecting film is trapezoidal and the shortest pit cross-sectional shape after forming the reflecting film is triangular.
An optical disk apparatus which reproduces an optical disk including information pits, the shortest pit thereof is formed into a conical shape,
- the optical disk apparatus is constituted so as to perform information reproduction by a PRML (Partial Response and Maximum Likelihood) method and reproduce the optical disk that an asymmetry of an information reproduction signal is +0.10 or lower.
Dependencies are inferred from the claim text.