Optical disk medium and method and apparatus for reading information
AssigneeMatsushita Electric Industrial Co., Ltd.
InventorsHiromichi Ishibashi, Shigeru Furumiya, Atsushi Nakamura, Junichi Minamino, Takashi Ishida
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Abstract
An optical disk medium includes a track groove thereon. On the optical disk medium, information is recorded along the track groove on a block unit basis. The block unit has a predetermined length. The block unit having the predetermined length includes a number of sub-blocks that are arranged along the groove. A sub-block mark is provided within each of the sub-blocks and used to identify the sub-block.
Claims10
A method for reading address information from an optical disk medium which comprises a track groove thereon and on which information is recorded along the track groove on a block unit basis, the block unit having a predetermined length,
- wherein the block unit includes a number of sub-blocks that are arranged along the groove,
- wherein a sub-block mark is provided within each said sub-block and used to identify the sub-block, and
- wherein a part of the track groove has a sawtooth-like wobble shape that is defined by a combination of a steep displacement pattern and a gentle displacement pattern to represent address information of the block unit, the method comprising:
- generating a first sync signal and multiplying the first sync signal and a read signal together to obtain a first product, the read signal having been detected in accordance with the wobble of the track groove and having a basic frequency, the first sync signal being synchronized with the read signal and having a frequency that is equal to the basic frequency of the read signal;
- generating a second sync signal and multiplying the second sync signal and the read signal together to obtain a second product, the second sync signal being synchronized with the read signal and having a frequency that is twice as high as the basic frequency of the read signal;
- integrating the first and second products to obtain an integral;
- and
- comparing the integral with a predetermined threshold value, thereby defining the address information.
An apparatus for reading address information from an optical disk medium which comprises a track groove thereon and on which information is recorded along the track groove on a block unit basis, the block unit having a predetermined length,
- wherein the block unit includes a number of sub-blocks that are arranged along the groove,
- wherein a sub-block mark is provided within each said sub-block and used to identify the sub-block, and
- wherein a part of the track groove has a sawtooth-like wobble shape that is defined by a combination of a steep displacement pattern and a gentle displacement pattern to represent address information of the block unit, the apparatus comprising:
- a first multiplier for multiplying a first sync signal and a read signal together, the read signal having been detected in accordance with the wobble of the track groove and having a basic frequency, the first sync signal being synchronized with the read signal and having a frequency that is equal to the basic frequency of the read signal;
- a second multiplier for multiplying a second sync signal and the read signal together, the second sync signal being synchronized with the read signal and having a frequency that is twice as high as the basic frequency of the read signal;
- integrating means for integrating outputs of the first and second multipliers;
- and
- means for comparing an output value of the integrating means with a predetermined threshold value, thereby defining the address information.
An optical disk medium which comprises a track groove thereon and on which information is recorded along the track groove,
- wherein the track groove includes a number of unit sections that are arranged along the track groove and that have side faces displaced periodically along the track groove, and
- wherein subdivided information is allocated to each said unit section and is represented by a shape that has been given to the side faces of the unit section, and
- wherein each said unit section has
- a first side displacement pattern that has been so defined as to make a signal waveform rise relatively steeply and fall relatively gently, or
- a second side displacement pattern that has been so defined as to make a signal waveform rise relatively gently and fall relatively steeply, and
- wherein an identification mark is formed at the beginning of each said unit section and used to identify the unit section, and
- wherein the identification mark has a side displacement pattern, which is distinguishable from the first and second side displacement patterns, and represents the same information as the subdivided information that is represented by the shape given to its associated unit section.
Dependencies are inferred from the claim text.