Optical disc, and reading system and manufacturing method of the disc
AssigneePioneer Electronic Corporation
InventorsKazuo Kuroda, Toshio Suzuki, Eiji Muramatsu
Life of this patent
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Abstract
A writable optical disc has an information writing track, and a guiding track for introducing a laser beam to the information writing track. The guiding track has prepit information recorded thereon, the prepit information including at least address information of the optical disc. The prepit information is recorded on the guiding track at a position where interference of adjacent guiding tracks with the prepit information is prevented. The information writing track is a groove track, and the guiding track is a land track.
Claims4
A reading system for reading a writable optical disc having an information writing track, and a guiding track for introducing a laser beam to the information writing track, and prepit information including address information recorded on the guiding track, the system comprising:
- a photodetector having photodetecting elements divided at least by a dividing line optically parallel with a radial direction of the disc for detecting reflected light of a laser beam irradiated to the information writing track,
- difference signal producing means for producing a difference signal based on a difference between outputs of the divided photodetecting elements,
- addition signal producing means for producing an addition signal based on an addition between outputs of the divided photodetecting elements,
- noise cancel signal producing means for producing a noise cancel signal which cancels noise component of the difference signal occurring by information recorded on the information writing track based on the addition signal, and
- prepit signal producing means for producing a prepit signal based on subtracting the noise cancel signal from the difference.
A reading system for reading a writable optical disc having an information writing track, and a guiding track for introducing a laser beam to the information writing track, and prepit information including address information recorded on the guiding track, the system comprising:
- a photodetector having photodetecting elements divided at least by a dividing line optically parallel with a radial direction of the disc for detecting reflected light of a laser beam irradiated to the information writing track,
- a first subtractor for producing a difference signal based on a difference between outputs of the divided photodetecting elements,
- an adder for producing an addition signal based on an addition between outputs of the divided photodetecting elements, a wave form shaping circuit for producing a noise cancel signal which cancels noise component of the difference signal occurring by information recorded on the information writing track based on the addition signal, and
- a second subtractor for producing a prepit signal based on subtracting the noise cancel signal from the difference.
Dependencies are inferred from the claim text.