Optical disc, tracking controlling apparatus and method, and focus controlling apparatus and method
AssigneeSony Corporation
InventorShoei Kobayashi
Life of this patent
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Abstract
An optical disc 1 has spiral grooves GR formed on a data recording surface thereof and in which information is written to, and read from, both a land between the grooves and the grooves as tracks. Each track has a plurality of address areas AR1 and user areas AR2 formed thereon, and each of the address areas AR1 has embossed pits for a groove header GRH and embossed pits for a land header LH. Each of the address areas AR1 has provided in a leading part thereof a header mark area HM formed from a mirror finished surface. That is, this optical disc is of an on-land/in-groove recording type. An offset taking place in a tracking error signal and focus error signal is removed to accurately control the tracking and focus of an optical head.
Claims10
A focus controlling apparatus, for use with an optical disc having spiral grooves formed on a data recording surface thereof and in which information is written to, and read from, both a land between the grooves and the grooves as tracks, each track having formed thereon a plurality of address areas and user areas, each of the address areas having formed thereon embossed pits for a groove header and embossed pits for a land header, and each of the address areas having provided in a leading part thereof a header mark area formed from a mirror finished surface, the apparatus comprising:
- means for generating a focus error signal from a detection output provided from an optical head which irradiates a laser beam to, and detects a reflected light of the irradiated laser beam from, a data recording surface of the optical disc;
- means for detecting a header mark area of the address area based on the detection output provided from the optical head;
- means for sampling and holding, based on the detection output provided from the header mark area detecting means, a focus error signal generated by the focus error generating means from the detection output provided from the optical head staying in the header mark area of the address area;
- a first means for detecting a difference between the focus error signal generated by the focus error generating means and the focus error signal sampled and held by the sampling and holding means;
- a second means for detecting a difference between the focus error signal generated by the focus error signal generating means and the difference detection output provided from the first difference detecting means;
- and
- means for controlling the focus of the optical head using as a focus error signal the difference detection output provided from the second difference detecting means.
A focus controlling method, for use with an optical disc having spiral grooves formed on a data recording surface thereof and in which information is written to, and read from, both a land between the grooves and the grooves as tracks, each track having formed thereon a plurality of address areas and user areas, each of the address areas having formed thereon embossed pits for a groove header and embossed pits for a land header, and each of the address areas having provided in a leading part thereof a header mark area formed from a mirror finished surface, the method comprising the steps of:
- generating a focus error signal from a detection output provided from an optical head which irradiates a laser beam to, and detects a reflected light of the irradiated laser beam from, a data recording surface of the optical disc;
- detecting a header mark area of the address area based on the reflected light detection output;
- sampling and holding, based on the header mark area detection output, a focus error signal generated from the reflected light detection output provided from the optical head staying in the header mark area of the address area;
- firstly detecting a difference between the focus error signal generated from the reflected light detection output and the sampled and held focus error signal;
- secondly detecting a difference between the difference detection output generated from the reflected light detection output and the difference detection output obtained by the first difference detection;
- and
- controlling the focus of the optical head using as a focus error signal the difference detection output obtained from the second difference detection.
A focus controlling apparatus, for use with an optical disc having spiral grooves formed on a data recording surface thereof and in which information is written to, and read from, both a land between the grooves and the grooves as tracks, each track having formed thereon a plurality of address areas and user areas, each of the address areas having formed thereon embossed pits for a groove header and embossed pits for a land header, and each of the address areas having provided in a leading part thereof a header mark area formed from a mirror finished surface and grooves, the apparatus comprising:
- means for generating a focus error signal from a detection output provided from an optical head which irradiates a laser beam to, and detects a reflected light of the irradiated laser beam from, a data recording surface of the optical disc;
- means for detecting a header mark area of the address area based on the detection output provided from the optical head;
- means for sampling and holding, based on the detection output provided from the header mark area detecting means, a focus error signal generated by the focus error generating means from the detection output provided from the optical head staying in the header mark area of the address area;
- a first means for detecting a difference between the focus error signal generated by the focus error generating means and the focus error signal sampled and held by the sampling and holding means;
- a second means for detecting a difference between the focus error signal generated by the focus error signal generating means and the difference detection output provided from the first difference detecting means;
- and
- means for controlling the focus of the optical head using as a focus error signal the difference detection output provided from the second difference detecting means.
A focus controlling method, for use with an optical disc having spiral grooves formed on a data recording surface thereof and in which information is written to, and read from, both a land between the grooves and the grooves as tracks, each track having formed thereon a plurality of address areas and user areas, each of the address areas having formed thereon embossed pits for a groove header and embossed pits for a land header, and each of the address areas having provided in a leading part thereof a header mark area formed from a mirror finished surface and grooves, the method comprising the steps of:
- generating a focus error signal from a detection output provided from an optical head which irradiates a laser beam to, and detects a reflected light of the irradiated laser beam from, a data recording surface of the optical disc;
- detecting a header mark area of the address area based on the reflected light detection output;
- sampling and holding, based on the header mark area detection, a focus error signal generated from the reflected light detection output with the optical head in the header mark area of the address area;
- firstly detecting a difference between the focus error signal generated from the reflected light detection output and the sampled and held tracking error signal;
- secondly detecting a difference between the focus error signal generated from the reflected light detection output and the difference detection output obtained by the first difference detection;
- and
- controlling the focus of the optical head using as a tracking error signal the difference detection output obtained by the second difference detection.
Dependencies are inferred from the claim text.