Method and apparatus for writing servo information in a disk drive

Abstract

According to one embodiment, a servo information writing method for use in a disk drive, for recording the servo information, forming a continuous servo track such as a spiral track. In this servo information writing method, the head is stopped when a write error is detected while the servo information is being written, and the head is then moved again at a constant speed and starts writing the servo information again, at the position where the write error has occurred.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

A general architecture that implements the various feature of the invention will now be described with reference to the drawings. The drawings and the associated descriptions are provided to illustrate embodiments of the invention and not to limit the scope of the invention.

FIG. 1 is a block diagram showing the important components of a disk drive according to an embodiment of the present invention;

FIG. 2 is a function block diagram explaining a method of writing servo information, according to the embodiment;

FIG. 3 is a diagram explaining a pattern of servo information according to the embodiment;

FIG. 4 is a diagram explaining a servo track provided on a disk, according to the embodiment;

FIG. 5 is a diagram representing servo information according to the embodiment;

FIG. 6 is a diagram explaining the difference between servo information recorded in a spiral servo track and servo information recorded in concentric servo tracks;

FIG. 7 is a schematic representation of servo information recorded in concentric servo tracks;

FIG. 8 is a schematic representation of the servo information related to the embodiment;

FIG. 9 is a diagram showing servo information recorded in a specific manner in the embodiment;

FIG. 10 is a diagram showing servo information recorded in another manner in the embodiment;

FIG. 11 is a flowchart explaining a sequence of blocks of writing servo information in the embodiment;

FIG. 12 a flowchart explaining a procedure of switching the servo information writing to a retry process in the embodiment;

FIG. 13 is a flowchart explaining a process starting with error detection and ending with a retry process;

FIG. 14 a block diagram explaining a specific method of detecting errors in the embodiment;

FIG. 15 is a diagram explaining a specific method of detecting head-positioning errors in the embodiment;

FIG. 16 is a flowchart explaining the blocks of the retry process performed in the embodiment;

FIGS. 17A to 17C are diagrams explaining a method of finding the approach distance for the retry process performed in the embodiment;

FIG. 18 is a diagram explaining a case where the retry process ends in failure;

FIGS. 19A to 19D are diagrams explaining a specific method of setting an approach distance;

FIG. 20 is a flowchart explaining a method of storing the data representing where the head is moving;

FIGS. 21A to 21D are diagrams explaining how a retry process is performed by using sync pulses in the embodiment; and

FIG. 22 is a flowchart explaining another embodiment of the present invention.

Claims

1. A method of writing servo information in a disk medium for a disk drive including a head, the method comprising: moving the head continuously at a constant speed from a first designated position at an inner or outer periphery of the disk medium that is rotating;making the head write servo information, thereby forming a continuous servo track on the disk medium;detecting a write error while the servo information is being written;stopping the head when the write error is detected, moving the head again at the constant speed at a second designated position based on the position where the head is stopped, and performing a retry process of writing the servo information from a position where the write error has occurred on the disk medium.

2. The method according to claim 1, wherein the servo information is information recorded in a plurality of servo sectors which are spaced at regular intervals in a circumferential direction of the disk medium and which constitute a spiral servo track, as the continuous servo track, on the disk medium.

3. The method according to claim 1, wherein the retry process of writing the servo information comprises: calculating an approach distance that the head needs to move to regain the constant speed after the head has been stopped; andmoving the head backward for a distance longer than the approach distance, from a position where the head is stopped, and then moving the head forward and making the head move again at the constant speed.

4. The method according to claim 1, wherein data representing a position that the head moving at the constant speed passes is stored in a memory when no write error is detected, and when a write error is detected, a position that the head passes immediately before the write error occurs is determined from the data stored in the memory and the retry process is performed to write the servo information again, starting at the position determined from the data stored in the memory.

5. The method according to claim 1, further comprising: storing data representing a position that the head moving at the constant speed passes is stored into a memory when no write error is detected,wherein, during the retry process, position that the head moving at the constant speed takes immediately before the write error occurs is determined from the data stored in memory, and an approach distance that the head needs to move to regain the constant speed after the head has been stopped is calculated from the position thus determined.

6. The method according to claim 1, further comprising: generating a sync pulse that is synchronous with a rotation of the disk medium,wherein, during the retry process, the head is moved again at the constant speed and the writing of servo information is re-tried, both in synchronism with the sync pulse.

7. The method according to claim 1, further comprising: generating a sync pulse that is synchronous with a rotation of the disk medium,wherein, during the retry process, an approach distance that the head needs to move to regain the constant speed after the head has been stopped is calculated in synchronism with the sync pulse, the head is moved backward for a distance longer than the approach distance thus calculated, from a position where the head is stopped, and then the head is moved again forward at the constant speed in synchronism with the sync pulse.

8. The method according to claim 1, wherein the write error is detected by when a head-positioning error with respect to a third designated position on the disk medium is detected while the servo information is being written at the third designated position.

9. The method according to claim 8, wherein the third designated position is given by a target-path generating unit.

10. The method according to claim 8, wherein the positioning error is detected when the deviation value of the head positioning relative to the third designated position on the disk medium exceed a predetermined tolerance range.

11. A disk drive comprising: a spindle motor which rotates a disk medium;an actuator which moves a head in a radial direction of the disk medium; anda controller which makes the head write servo information on the disk medium, thereby forming a continuous servo track on the disk medium,wherein the controller detects an error in writing the servo information, causes the head to move continuously at a constant speed in a radial direction of the disk medium from a first designated position at an inner or outer periphery of the disk medium, thereby to write the servo information on the disk medium, stops the head when the write error is detected, moves the heat again at the constant speed, thereby to start a retry process of writing the servo information again, at a position on the disk medium where the write error has been made.

12. The disk drive according to claim 11, wherein the controller has a servo information writing function of writing the servo information in a plurality of servo sectors which are spaced at regular intervals in a circumferential direction of the disk medium and which constitute, as the continuous servo track, a spiral servo track on the disk medium.

13. The disk drive according to claim 11, wherein, during the retry process, the controller calculates an approach distance that the head needs to move to regain the constant speed after the head has been stopped, makes the head moved backward for a distance longer than the approach distance thus calculated, from a position where the head is stopped, and then makes the head start moving again forward at the constant speed from a position to which the head has moved backward.

14. The disk drive according to claim 11, wherein when no write error is detected, the controller stores, into a memory, data representing a position the head moving at the constant speed passes, and when the write error is detected, the controller determines from the data stored in memory the position the head moving has passed immediately before the write error occurs, and performs the retry process to write the servo information again, starting at the position represented by the data stored in the memory.

15. The disk drive according to claim 11, wherein when no write error is detected, the controller stores, into a memory, data representing a position the head moving at the constant speed passes, and when a write error is detected, the controller determines, from the data stored in the memory, a position that the head passes immediately before the write error occurs, and calculates, from data stored in the memory and representing the position thus determined, an approach distance that the head needs to move to regain the constant speed after the head has been stopped.