Method and apparatus for controlling motor rotation in hard disk drive

1. A method of controlling a rotation of a motor in a disk drive, the method comprising:

performing spin-up when the disk drive is operating and determining whether a disk rotation speed is less than a predetermined target constant revolutions per minute (RPM);

rotating a disk at a predetermined low RPM when determining whether the disk drive operates at a low temperature and changing a rotation mode to a low-speed rotation mode when it is determined that the disk rotation speed is less than the predetermined target constant RPM; and

spinning up the disk to the target constant RPM when determining whether the temperature of the disk drive has increased and changing the rotation mode to a high-speed rotation mode when a disk rotation driving current decreases below a predetermined reference current value while the disk is rotating at the low RPM.

2. The method of claim 1 , wherein, in the determination whether a disk rotation speed is less than a predetermined target constant RPM, when an operation of the disk drive is initialized, a process of trying the spin-up and determining whether the disk rotation speed is less than the predetermined target constant RPM is performed a predetermined number of times.

3. The method of claim 2 , wherein the predetermined number of times is at least equal to 3.

4. The method of claim 1 , wherein the determination whether a disk rotation speed is less than a predetermined target constant RPM further comprises:

stopping an operation of the disk drive when determining that the disk drive cannot be operated when the disk rotation speed is less than first low RPM,

wherein the predetermined low RPM is the first low RPM which is the minimum rotation speed at which a head of the disk drive can be normally raised from the surface of the disk.

5. The method of claim 1 , wherein the rotation of the disk at the predetermined low RPM comprises:

rotating the disk at second low RPM by changing the rotation mode to a second low-speed rotation mode when the disk rotation speed is less than the predetermined target constant RPM and at least equal to the second low RPM; and

rotating the disk at first low RPM by changing the rotation mode to a first low-speed rotation mode when the disk rotation speed is less than the second low RPM and is at least equal to the first low RPM,

wherein the predetermined low RPM is divided into the first low RPM and the second low RPM which is faster than the first low RPM.

6. The method of claim 5 , wherein, in the rotation of the disk at first the low RPM, the disk is spun up to the second low RPM by determining that the temperature of the disk drive has increased and changing the rotation mode to the second low-speed rotation mode when the disk rotation driving current decreases below a predetermined second reference current value while the disk is rotating at the first low RPM.

7. The method of claim 1 , wherein the predetermined low RPM is the minimum rotation speed at which a head of the disk drive can be normally raised from the surface of the disk.

8. An apparatus for controlling a rotation of a motor in a disk drive comprising a spindle motor rotating a disk and a motor driver operating the spindle motor at specific revolutions per minute (RPM), the apparatus comprising:

an RPM detector detecting a rotation speed of the disk rotated by the spindle motor;

a driving current detector detecting a driving current applied to the spindle motor;

a reference value storage unit storing a predetermined target constant RPM, a predetermined low RPM, and a predetermined reference current value of the disk drive; and

a spin-up controller transmitting a signal to the motor driver for spinning up the disk to the predetermined target constant RPM, transmitting a signal to the motor driver for rotating the disk at the predetermined low RPM when determining that the disk drive operates at a low temperature and changing a rotation mode to a low-speed rotation mode when the disk rotation speed detected by the RPM detector is less than the predetermined target constant RPM, and transmitting a signal to the motor driver for spinning up the disk to the target constant RPM to the motor driver when determining that the temperature of the disk drive has increased and changing the rotation mode to a high-speed rotation mode when the driving current detected by the driving current detector decreases below the predetermined reference current value while the disk is rotating at the low RPM.

9. The apparatus of claim 8 , wherein the spin-up controller performs, a predetermined number of times, a process of transmitting a signal for spinning up the disk to the target constant RPM to the motor driver and determining whether the disk rotation speed detected by the RPM detector is less than the predetermined target constant RPM when an operation of the disk drive is initialized.

10. The apparatus of claim 9 , wherein the predetermined number of times is at least equal to 3.

11. The apparatus of claim 8 , wherein the reference value storage unit stores a first low RPM which is the minimum rotation speed at which a head of the disk drive can be normally raised from the surface of the disk, and

the spin-up controller transmits a signal to the motor driver for stopping an operation of the spindle motor when determining that the disk drive cannot be operated when the disk rotation speed detected by the RPM detector is less than the first low RPM.

12. The apparatus of claim 8 , wherein the reference value storage unit stores a first low RPM and a second low RPM, which is faster than the first low RPM, for the predetermined low RPM, and

the spin-up controller transmits a signal to the motor driver for rotating the disk at the second low RPM by changing the rotation mode to a second low-speed rotation mode when the disk rotation speed detected by the RPM detector is less than the predetermined target constant RPM and at least equal to the second low RPM, and transmits a signal to the motor driver for rotating the disk at the first low RPM by changing the rotation mode to a first low-speed rotation mode when the disk rotation speed detected by the RPM detector is less than the second low RPM and at least equal to the first low RPM.

13. The apparatus of claim 12 , wherein the spin-up controller transmits a signal to the motor driver for spinning up the disk to the second low RPM when determining that the temperature of the disk drive has increased and changing the rotation mode to the second low-speed rotation mode when the driving current detected by the driving current detector decreases below a predetermined second reference current value while the disk is rotating at the first low RPM.

14. The apparatus of claim 8 , wherein the predetermined low RPM is the minimum rotation speed at which a head of the disk drive can be normally raised from the surface of the disk.

15. A hard disk drive, comprising:

an RPM detector detecting a rotation speed of a disk rotated by a spindle motor;

a driving current detector detecting a driving current applied to the spindle motor;

a reference value storage unit storing a target constant RPM, a low RPM, and a reference current value of the disk drive; and

a spin-up controller transmitting a signal to the motor driver for spinning up the disk to the predetermined target constant RPM, transmitting a signal to the motor driver for rotating the disk at the predetermined low RPM when determining that the disk drive operates at a low temperature and changing a rotation mode to a low-speed rotation mode when the disk rotation speed detected by the RPM detector is less than the predetermined target constant RPM, and transmitting a signal to the motor driver for spinning up the disk to the target constant RPM to the motor driver when determining that the temperature of the disk drive has increased and changing the rotation mode to a high-speed rotation mode when the driving current detected by the driving current detector decreases below the predetermined reference current value while the disk is rotating at the low RPM.

16. A computer readable recording medium encoded with processing instructions for causing a processor to execute a method of controlling a rotation of a motor in a disk drive, the method comprising:

performing spin-up when the disk drive is operating and determining whether a disk rotation speed is less than a predetermined target constant revolutions per minute (RPM);

rotating a disk at a predetermined low RPM when determining whether the disk drive operates at a low temperature and changing a rotation mode to a low-speed rotation mode when it is determined that the disk rotation speed is less than the predetermined target constant RPM; and

spinning up the disk to the target constant RPM when determining whether the temperature of the disk drive has increased and changing the rotation mode to a high-speed rotation mode when a disk rotation driving current decreases below a predetermined reference current value while the disk is rotating at the low RPM.