Optical storage device and emission control method
View Patent ↗An optical storage device decreases the influence of return light to the laser light source and prevents an increase of power consumption even if high frequency superimposing is performed. The optical storage device applies drive current, to which a high frequency signal is superimposed, to the laser light source, and reads/writes data from/in the storage medium. The high frequency superimposing is set to OFF as a default to save power consumption, and high frequency superimposing is turned ON only when it is judged that servo is unstable, and high frequency superimposing is turned OFF when it is judged that servo is stable.
1. An optical storage device for writing and/or reading data to/from a storage medium using a laser beam, comprising:
a light source for emitting the laser beam onto said storage medium;
a servo controller for performing follow-up control of said laser beam on said storage medium according to the reflected light of said storage medium;
a light source driver for applying drive current to said light source for said writing and/or reading;
a signal generator for generating high frequency signals to be superimposed onto said drive current; and
a controller for judging whether the laser emission of said light source is unstable from the servo control status by said servo controller, and superimposing said high frequency signals onto said drive current when judging that the laser emission is unstable, and
wherein the controller cancels superimposing of said high frequency signals onto said drive current when judging that the laser emission is stable from the servo control status by the servo controller.
2. The optical storage device according to claim 1 , wherein said controller judges whether the probability that said servo control becomes OFF is high from the servo control status by said servo controller, superimposes said high frequency signals onto said drive current when judging high, and cancels superimposing of said high frequency signals onto said drive current when judging low.
3. The optical storage device according to claim 1 , wherein said signal generator comprises:
oscillation means for generating said high frequency signals; and
a switch for superimposing said generated high frequency signals onto said drive current by controlling of said controller.
4. The optical storage device according to claim 1 , wherein said controller counts the number of times when said servo control became OFF, and judges whether said laser emission is unstable according to said count value.
5. The optical storage device according to claim 1 , wherein said servo controller comprises:
an error detecting unit for detecting the follow-up error of said laser beam from said reflected light; and
a servo controlling unit for turning said servo control OFF when said error is a predetermined value or more, and for performing follow-up control of said laser beam when said error is not a predetermined value or more.
6. The optical storage device according to claim 1 , wherein said servo control is a track servo control for following up said laser beam on the tracks of said storage medium.
7. The optical storage device according to claim 1 , wherein said light source driver applies drive current according to one of the operations of writing, reading and erasing data in/from said storage medium,
and said controller controls superimposing of said high frequency signal during said erasing.
8. An emission control method of controlling emission of the laser light source for irradiating light onto a storage medium, comprising:
a servo controlling step of performing follow-up control of said laser beam on said storage medium according to the reflected light of said storage medium;
a step of judging whether emission of said laser light source is unstable from the servo control status by said servo control;
a step of superimposing high frequency signals onto the drive current supplied to said laser light source when judging that the laser emission is unstable; and
a step of canceling said superimposing of said high frequency signals onto said drive current when judging that the laser emission is stable from the servo control status by the servo control.
9. The emission control method according to claim 8 , wherein said judgment step comprises a step of judging whether the probability that said servo control becomes OFF is high from the servo control status by said servo control, and said step of superimposing comprises a step of superimposing high frequency signals onto said drive current when said probability is high, and canceling the superimposing of high frequency signals onto said drive current when said probability is low.
10. The emission control method according to claim 8 , wherein said step of superimposing high frequency signals comprises:
a step of generating high frequency signals; and
a step of superimposing said generated high frequency signals onto said drive current by operating a switch.
11. The emission control method according to claim 8 , wherein said judgment step comprises:
a step of counting the number of times when said servo control became OFF; and
a step of judging whether said laser emission is unstable according to said count value.
12. The emission control method according to claim 8 , wherein said servo controlling step comprises:
an error detecting step of detecting the follow-up error of said laser beam from said reflected light; and
a servo controlling step of turning said servo control OFF when said error is a predetermined value or more, and performing follow-up control of said laser beam when said error is not a predetermined value or more.
13. The emission control method according to claim 8 , wherein said servo control is a track servo control for causing said laser beam to follow the tracks of said storage medium.
14. The emission control method according to claim 8 , wherein said superimposing step comprise a step of superimposing said high frequency signal during erasing to said drive current according to one of the operations of writing, reading and erasing data in/from said storage medium.
15. An optical storage device for writing and/or reading data to/from a storage medium using a laser beam, comprising:
a light source for emitting the laser beam onto said storage medium;
a servo controller for performing follow-up control of said laser beam on said storage medium according to the reflected light of said storage medium;
a light source driver for applying drive current to said light source for said writing and/or reading;
a signal generator for generating high frequency signals to be superimposed onto said drive current; and
a controller for judging whether the laser emission of said light source is unstable from the servo control status by said servo controller, and superimposing said high frequency signals onto said drive current when judging that the laser emission is unstable;
wherein said controller counts the number of times when said servo control became OFF, and judges whether said laser emission is unstable according to said count value.