Optical disk apparatus and its reproducing method
View Patent ↗Amplitude and frequency of a high-frequency signal superposed on a reproduction laser beam are changed in accordance with a reproduction spot diameter on the surface of the recording layer upon discrimination of an optical disk in initial adjustment after insertion of the optical disk and change of a layer of a multi-layer optical disk. Further, the high-frequency signal is not superposed on the reproduction laser beam until end of the discrimination and change to a target layer upon discrimination of the optical disk and change of a layer of a multi-layer optical disk.
1. An optical disk apparatus which reproduces first and second optical disks, comprising:
a laser to emit a laser beam having a predetermined wavelength;
a first objective lens to focus the laser beam having the predetermined wavelength emitted from the laser on the first optical disk and having a first numerical aperture;
a second objective lens to focus the laser beam having the predetermined wavelength emitted from the laser on the second optical disk and having a second numerical aperture;
an optical disk discrimination circuit to discriminate a kind of the optical disk mounted; and
a laser driver to supply a laser driving current on which a first high-frequency current having a first amplitude and a first frequency is superposed to the laser when the first optical disk is mounted and to supply a laser driving current on which a second high-frequency current having a second amplitude and a second frequency is superposed to the laser when the second optical disk is mounted,
wherein the laser driver supplies a laser driving current on which no high-frequency current is superposed to the laser when the optical disk discrimination circuit discriminates the kind of the optical disk before the optical disk apparatus reproduces information on the optical disk, and supplies a laser driving current on which the first or second high-frequency current is superposed to the laser after the optical disk discrimination circuit discriminates the kind of the optical disk.
2. An optical disk apparatus according to claim 1 , wherein
the laser driver includes:
a first high-frequency current generation circuit to generate the first high-frequency current having the first amplitude and the first frequency;
a second high-frequency current generation circuit to generate the second high-frequency current having the second amplitude and the second frequency; and
a signal selection circuit to selectively output an output of the first high-frequency current generation circuit or an output of the second high-frequency current generation circuit.
3. An optical disk apparatus according to claim 1 , wherein
the laser driver includes a high-frequency current generation circuit which can change amplitude and frequency of a high-frequency current on the basis of an external control signal to generate the first or second high-frequency current.
4. An optical disk apparatus which reproduces first and second optical disks, comprising:
a laser to emit a laser beam having a predetermined wavelength;
a first objective lens to focus the laser beam having the predetermined wavelength emitted from the laser on the first optical disk and having a first numerical aperture;
a second objective lens to focus the laser beam having the predetermined wavelength emitted from the laser on the second optical disk and having a second numerical aperture;
an optical disk discrimination circuit to discriminate a kind of the optical disk mounted; and
a laser driver to supply a laser driving current on which a first high-frequency current having a first amplitude and a first frequency is superposed to the laser when the optical disk is reproduced using the laser beam having a first spot diameter through the first objective lens and to supply a laser driving current on which a second high-frequency current having a second amplitude and a second frequency is superposed to the laser when the optical disk is reproduced using the laser beam having a second spot diameter through the second objective lens,
wherein the laser driver supplies a laser driving current on which no high-frequency current is superposed to the laser when the optical disk discrimination circuit discriminates the kind of the optical disk before the optical disk apparatus reproduces information on the optical disk, and supplies a laser driving current on which the first or second high-frequency current is superposed to the laser after the optical disk discrimination circuit discriminates the kind of the optical disk.
5. An optical disk apparatus according to claim 4 , wherein
the laser driver includes:
a first high-frequency current generation circuit to generate the first high-frequency current having the first amplitude and the first frequency;
a second high-frequency current generation circuit to generate the second high-frequency current having the second amplitude and the second frequency; and
a signal selection circuit to selectively output an output of the first high-frequency current generation circuit or an output of the second high-frequency current generation circuit.
6. An optical disk apparatus according to claim 4 , wherein
the laser driver includes a high-frequency current generation circuit which can change amplitude and frequency of a high-frequency current on the basis of an external control signal to generate the first or second high-frequency current.
7. An optical disk apparatus which reproduces first and second optical disks, comprising:
a laser to emit a laser beam having a predetermined wavelength;
a first objective lens to focus the laser beam having the predetermined wavelength emitted from the laser on the first optical disk and having a first numerical aperture;
a second objective lens to focus the laser beam having the predetermined wavelength emitted from the laser on the second optical disk and having a second numerical aperture;
an optical disk discrimination circuit to discriminate a kind of the optical disk mounted; and
a laser driver to supply a laser driving current on which a first high-frequency current having a first amplitude and a first frequency is superposed to the laser when the optical disk is reproduced using the laser beam having a first average laser power and to supply a laser driving current on which a second high-frequency current having a second amplitude and a second frequency is superposed to the laser when the optical disk is reproduced using the laser beam having a second average laser power,
wherein the laser driver supplies a laser driving current on which no high-frequency current is superposed to the laser when the optical disk discrimination circuit discriminates the kind of the optical disk before the optical disk apparatus reproduces information on the optical disk, and supplies a laser driving current on which the first or second high-frequency current is superposed to the laser after the optical disk discrimination circuit discriminates the kind of the optical disk.
8. An optical disk apparatus according to claim 7 , wherein
the laser driver includes:
a first high-frequency current generation circuit to generate the first high-frequency current having the first amplitude and the first frequency;
a second high-frequency current generation circuit to generate the second high-frequency current having the second amplitude and the second frequency; and
a signal selection circuit to selectively output an output of the first high-frequency current generation circuit or an output of the second high-frequency current generation circuit.
9. An optical disk apparatus according to claim 7 , wherein
the laser driver includes a high-frequency current generation circuit which can change amplitude and frequency of a high-frequency current on the basis of an external control signal to generate the first or second high-frequency current.
10. An optical disk apparatus according to claim 7 , further comprising
a monitor diode to observe laser power of the laser beam emitted from the laser, and
wherein
the laser driver is controlled on the basis of average laser power observed by the monitor diode.
11. An optical disk apparatus which reproduces a first recording layer disposed at a first distance from a surface of an optical disk and a second recording layer disposed at a second distance from the surface of the optical disk, comprising:
a laser to emit a laser beam having a predetermined wavelength;
a first objective lens to focus the laser beam having the predetermined wavelength emitted from the laser on the first recording layer and having a first numerical aperture;
a second objective lens to focus the laser beam having the predetermined wavelength emitted from the laser on the second recording layer and having a second numerical aperture; and
a laser driver to supply a laser driving current on which a first high-frequency current having a first amplitude and a first frequency is superposed to the laser when the first recording layer is reproduced and to supply the laser driving current on which a second high-frequency current having a second amplitude and a second frequency is superposed to the laser when the second recording layer is reproduced,
wherein the laser driver supplies a laser driving current on which no high-frequency current is superposed to the laser when the kind of the optical disk is discriminated before the optical disk apparatus reproduces information on the optical disk, and supplies a laser driving current on which the first or second high-frequency current is superposed to the laser when the first or second recording layer is reproduced.
12. An optical disk apparatus according to claim 11 , wherein
the laser driver includes:
a first high-frequency current generation circuit to generate the first high-frequency current having the first amplitude and the first frequency;
a second high-frequency current generation circuit to generate the second high-frequency current having the second amplitude and the second frequency; and
a signal selection circuit to selectively output an output of the first high-frequency current generation circuit or an output of the second high-frequency current generation circuit.
13. An optical disk apparatus according to claim 11 , wherein
the laser driver includes a high-frequency current generation circuit which can change amplitude and frequency of a high-frequency current on the basis of an external control signal to generate the first or second high-frequency current.
14. A method of reproducing first and second optical disks, comprising:
supplying a laser driving current on which a high-frequency current having a first amplitude and a first frequency is superposed to a laser when the first optical disk is mounted;
supplying a laser driving current on which the high-frequency current having a second amplitude and a second frequency is superposed to the laser when the second optical disk is mounted;
supplying a laser driving current on which no high-frequency current is superposed to the laser when the kind of the optical disk is discriminated before the optical disk apparatus reproduces information on the optical disk; and
supplying a laser driving current on which the high-frequency current is superposed to the laser after the kind of the optical disk is discriminated.
15. A method of reproducing first and second optical disks, comprising:
supplying a laser driving current on which a high-frequency current having a first amplitude and a first frequency is superposed to a laser when the optical disk is reproduced using a laser beam having a first spot diameter;
supplying a laser driving current on which the high-frequency current having a second amplitude and a second frequency is superposed to the laser when the optical disk is reproduced using the laser beam having a second spot diameter;
supplying a laser driving current on which no high-frequency current is superposed to the laser when the kind of the optical disk is discriminated before the optical disk apparatus reproduces information on the optical disk; and
supplying a laser driving current on which the high-frequency current is superposed to the laser after the kind of the optical disk is discriminated.
16. A method of reproducing first and second optical disks, comprising:
supplying a laser driving current on which a high-frequency current having a first amplitude and a first frequency is superposed to a laser when the optical disk is reproduced using a laser beam having first average laser power;
supplying a laser driving current on which the high-frequency current having a second amplitude and a first frequency is superposed to the laser when the optical disk is reproduced using the laser beam having second average laser power;
supplying a laser driving current on which no high-frequency current is superposed to the laser when the kind of the optical disk is discriminated before the optical disk apparatus reproduces information on the optical disk; and
supplying a laser driving current on which the high-frequency current is superposed to the laser after the kind of the optical disk is discriminated.
17. An optical disk reproduction method of reproducing a first recording layer disposed at a first distance from a surface of an optical disk and a second recording layer disposed at a second distance from the surface of the optical disk, comprising:
supplying a laser driving current on which a high-frequency current having a first amplitude and a first frequency is superposed to a laser when the first recording layer is reproduced; and
supplying a laser driving current on which the high-frequency current having a second amplitude and a second frequency is superposed to the laser when the second recording layer is reproduced,
wherein the laser driver supplies a laser driving current on which no high-frequency current is superposed to the laser when the kind of the optical disk is discriminated depending on kind of the optical disk before the optical disk apparatus reproduces information on the optical disk, and supplies a laser driving current on which the first or second high-frequency current is superposed to the laser when the first or second recording layer is reproduced.