Optical disc and optical disc apparatus
View Patent ↗The invention provides an optical disc apparatus which prevents that a laser beam whose power is set at a read power level causes erroneous data recording or deletion. The optical disc apparatus includes an emission controller which controls an amount of an electrical current that a current supply portion supplies to a laser diode in order to control a level of emission power at which the laser diode emits the laser beam. The emission controller has a function to set levels of the emission power at the following transition processings: a transition processing after a read processing and before a write processing, a transition processing after a write processing and before a read processing, a transition processing between two read processings for respective areas, and a transition processing between two write processings for respective areas.
1. An optical disc apparatus which reads information from an optical disc using a laser beam, the apparatus comprising:
a laser diode;
a current supply portion which supplies an electrical current for emitting the laser beam from the laser diode; and
an emission controller which controls an amount of the electrical current that the current supply portion supplies to the laser diode in order to control a level of emission power at which the laser diode emits the laser beam;
the emission controller having a function to set the level of the emission power at a time of at least one of the following transition processings: a transition processing after a read processing and before a write processing, a transition processing after a write processing and before a read processing, a transition processing between two read processings for respective areas, and a transition processing between two write processings for respective areas,
wherein the optical disc has a plurality of layers having respective levels of resistance to a laser beam emitted for reading, and the emission controller sets the emission power at the time of the at least one transition processing at a level not higher than a read power level for the layer that has the lowest resistance.
2. The optical disc apparatus according to claim 1 , wherein the at least one transition processing includes a movement of a focal point of the laser beam from one of the layers to another layer as a target layer.
3. The optical disc apparatus according to claim 2 , wherein after the at least one transition processing is completed, the emission controller sets the emission power at a read power level or a write power level for the target layer.
4. The optical disc apparatus according to claim 1 , wherein the emission controller sets the emission power at the time of the at least one transition processing at a level capable of generating a focus error signal.
5. An optical disc apparatus which reads information from an optical disc using a laser beam, the apparatus comprising:
a laser diode;
a current supply portion which supplies an electrical current for emitting the laser beam from the laser diode; and
an emission controller which controls an amount of the electrical current that the current supply portion supplies to the laser diode in order to control a level of emission power at which the laser diode emits the laser beam;
the emission controller having a function to set the level of the emission power at a time of at least one of the following transition processings: a transition processing after a read processing and before a write processing, a transition processing after a write processing and before a read processing, a transition processing between two read processings for respective areas, and a transition processing between two write processings for respective areas,
wherein the optical disc has a plurality of layers having respective levels of resistance to a laser beam emitted for reading, and the emission controller sets the emission power at the time of the at least one transition processing at a level that can assure a predetermined reproduction quality with respect to one of the layers that has the lowest resistance when read is repeatedly performed on the optical disc a predetermined number of times at the power level.
6. The optical disc apparatus according to claim 5 , wherein the at least one transition processing includes a movement of a focal point of the laser beam from one of the layers to another layer as a target layer.
7. The optical disc apparatus according to claim 6 , wherein after the at least one transition processing is completed, the emission controller sets the emission power at a read power level or a write power level for the target layer.
8. The optical disc apparatus according to claim 5 , wherein the emission controller sets the emission power at the time of the at least one transition processing at a level capable of generating a focus error signal.
9. An optical disc apparatus which reads information from an optical disc using a laser beam, the apparatus comprising:
a laser diode;
a current supply portion which supplies an electrical current for emitting the laser beam from the laser diode; and
an emission controller which controls an amount of the electrical current that the current supply portion supplies to the laser diode in order to control a level of emission power at which the laser diode emits the laser beam;
the emission controller having a function to set the level of the emission power at a time of at least one of the following transition processings: a transition processing after a read processing and before a write processing, a transition processing after a write processing and before a read processing, a transition processing between two read processings for respective areas, and a transition processing between two write processings for respective areas,
wherein the emission controller sets the emission power at the time of the at least one transition processing at a level determined based on a signal obtained from reflected light from the respective layers when the layers are irradiated with a laser beam at a same power level.
10. A reading method which reads information from an optical disc using a laser beam, the method comprising steps of:
a current supply step which supplies an electrical current to a laser diode for emitting the laser beam from the laser diode; and
an emission control step which controls an amount of the electrical current that is supplied to the laser diode in order to control a level of emission power at which the laser diode emits the laser beam, wherein:
the emission control step comprises setting the level of the emission power at the time of at least one of the following transition processings: a transition processing after a read processing and before a write processing, a transition processing after a write processing and before a read processing, a transition processing between two read processings for respective areas, and a transition processing between two write processings for respective areas, and
the optical disc has a plurality of layers having respective levels of resistance to a laser beam emitted for reading, and the emission control step sets the emission power at the time of the at least one transition processing at a level not higher than a read power level for the layer that has the lowest resistance.
11. The reading method according to claim 10 , wherein the at least one transition processing includes moving a focal point of the laser beam from one of the layers to another layer as a target layer.
12. The reading method according to claim 11 , wherein after the at least one transition processing is completed, the emission control step sets the emission power at a read power level or a write power level for the target layer.
13. The reading method according to claim 10 , wherein the emission control step sets the emission power at the time of the at least one transition processing at a level capable of generating a focus error signal.
14. A reading method which reads information from an optical disc using a laser beam, the method comprising steps of:
a current supply step which supplies an electrical current to a laser diode for emitting the laser beam from the laser diode; and
an emission control step which controls an amount of the electrical current that is supplied to the laser diode in order to control a level of emission power at which the laser diode emits the laser beam, wherein:
the emission control step comprises setting the level of the emission power at a time of at least one of the following transition processings: a transition processing after a read processing and before a write processing, a transition processing after a write processing and before a read processing, a transition processing between two read processings for respective areas, and a transition processing between two write processings for respective areas, and
the optical disc has a plurality of layers having respective levels of resistance to a laser beam emitted for reading, and the emission control step sets the mission power at the time of the at least one transition processing at a level that can assure a predetermined reproduction quality with respect to one of the layers that has the lowest resistance when read is repeatedly performed on the optical disc in a predetermined number of times at the power level.
15. The reading method according to claim 14 , wherein the at least one transition processing includes moving a focal point of the laser beam from one of the layers to another layer as a target layer.
16. The reading method according to claim 15 , wherein after the at least one transition processing is completed, the emission control step sets the emission power at a read power level or a write power level for the target layer.
17. The reading method according to claim 14 , wherein the emission control step sets the emission power at the time of the at least one transition processing at a level capable of generating a focus error signal.
18. A read method which read information form an optical disc using a laser beam, the method comprising steps of:
a current supply step which supplied an electrical current to a laser diode for emitting the laser beam from the laser diode; and
an emission control step which controls an amount of the electrical current that is supplied to the laser diode in order to control a level of emission power at which the laser diode emits the laser beam, wherein:
the emission control step has a function to set the level of the emission power at a time of at least one of the following transition processing: a transition processing after a read processing and before a write processing, a transition processing after a write processing and before a read processing, a transition processing between two read processings for respective areas, and a transition processing between two write processings for respective areas, and
the emission control step sets the emission power at the time of the at least one transition processing at a level determined based on a signal obtained from reflected light from the respective layers when the layers are irradiated with a laser beam at a same power level.