Storage device, head returning method, and head returning apparatus

1. A storage device that returns a head, which is retracted from a storage medium with a detection of an abnormality, onto the storage medium, the storage device comprising:

a time measuring unit that measures a duration time of a state relating to the detection of the abnormality when the head is retracted; and

a head-return determining unit that determines whether to return the head onto the storage medium based on the measured duration time.

2. The storage device according to claim 1 , wherein

the time measuring unit measures a duration time of not detecting the abnormality, and

when the measured duration time of not detecting the abnormality is longer than a predetermined threshold, the head-return determining unit allows a return of the head.

3. The storage device according to claim 1 , wherein

the time measuring unit measures a duration time of detecting the abnormality, and

when the measured duration time of detecting the abnormality is longer than a predetermined threshold, the head-return determining unit allows a return of the head.

4. The storage device according to claim 1 , wherein

the abnormality includes an occurrence of a shock,

the time measuring unit measures a duration time of not detecting any shock after a shock sensor has detected a shock, and

when the measured duration time of not detecting the shock is shorter than a predetermined threshold, the head-return determining unit does not allow a return of the head.

5. The storage device according to claim 4 , wherein

when the head-return determining unit does not allow the return of the head, the head-return determining unit controls the head in such a manner that the head is pressed against a stopper that is located at a retraction area.

6. The storage device according to claim 1 , wherein the abnormality includes a falling of the storage device,

the time measuring unit measures a duration time of the falling of the

storage device after a fall sensor has detected the falling of the storage device, and

when the measured duration time of the falling state is shorter than a predetermined threshold, the head-return determining unit does not allow a return of the head.

7. A method of returning a head, which is retracted from a storage medium with a detection of an abnormality, onto the storage medium, the method comprising:

measuring a duration time of a state relating to the detection of the abnormality when the head is retracted; and

determining whether to return the head onto the storage medium based on the measured duration time.

8. The method according to claim 7 , wherein

the measuring includes measuring a duration time of not detecting the abnormality, and

when the measured duration time of not detecting the abnormality is longer than a predetermined threshold, the determining includes allowing a return of the head.

9. The method according to claim 7 , wherein

the measuring includes measuring a duration time of detecting the abnormality, and

when the measured duration time of detecting the abnormality is longer than a predetermined threshold, the determining includes allowing a return of the head.

10. The method according to claim 7 , wherein

the abnormality includes an occurrence of a shock,

the measuring includes measuring a duration time of not detecting any shock after a shock sensor has detected a shock, and

when the measured duration time of not detecting the shock is shorter than a predetermined threshold, the determining includes not allowing a return of the head.

11. The method according to claim 10 , wherein

when the return of the head is not allowed, the determining includes controlling the head in such a manner that the head is pressed against a stopper that is located at a retraction area.

12. The method according to claim 7 , wherein

the abnormality includes a falling of the storage device,

the measuring includes measuring a duration time of the falling of the storage device after a fall sensor has detected the falling of the storage device, and

when the measured duration time of the falling state is shorter than a predetermined threshold, the determining includes not allowing a return of the head.

13. A computer program product comprising a computer usable medium having computer readable program codes embodied in the medium that when executed cause a computer to execute:

measuring a duration time of a state relating to the detection of the abnormality when the head is retracted; and

determining whether to return the head onto the storage medium based on the measured duration time.

14. An apparatus for returning a head, which is retracted from a storage medium with a detection of an abnormality, onto the storage medium, the apparatus comprising:

a time measuring unit that measures a duration time of a state relating to the detection of the abnormality when the head is retracted; and

a head-return determining unit that determines whether to return the head onto the storage medium based on the measured duration time.

15. The apparatus according to claim 14 , wherein

the time measuring unit measures a duration time of not detecting the abnormality, and

when the measured duration time of not detecting the abnormality is longer than a predetermined threshold, the head-return determining unit allows a return of the head.

16. The apparatus according to claim 14 , wherein

the time measuring unit measures a duration time of detecting the abnormality, and

when the measured duration time of detecting the abnormality is longer than a predetermined threshold, the head-return determining unit allows a return of the head.

17. The apparatus according to claim 14 , wherein

the abnormality includes an occurrence of a shock,

the time measuring unit measures a duration time of not detecting any shock after a shock sensor has detected a shock, and

when the measured duration time of not detecting the shock is shorter than a predetermined threshold, the head-return determining unit does not allow a return of the head.

18. The apparatus according to claim 17 , wherein

when the head-return determining unit does not allow the return of the head, the head-return determining unit controls the head in such a manner that the head is pressed against a stopper that is located at a retraction area.

19. The apparatus according to claim 14 , wherein

the abnormality includes a falling of the storage device,

the time measuring unit measures a duration time of the falling of the storage device after a fall sensor has detected the falling of the storage device, and

when the measured duration time of the falling state is shorter than a predetermined threshold, the head-return determining unit does not allow a return of the head.