JP2001143412A - Head-positioning method and disk drive - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stabilize signal level of recording and reproduction. SOLUTION: When an I/O request is received from a host device 30 (step S1), a target track position is calculated at this I/O request (step S2, target track position calculating process). Then an actuator for rough movement is driven towards the calculated target track position (step S3, rough positioning process). When the target track position is calculated in the process S2, a target yaw angle α of the head is calculated (step S4, target yaw-calculating process) before or after the driving of the actuator for rough movement begins is started. Furthermore, the head is driven up to the target yaw angle (step S5, fine positioning process), in parallel with the rough positioning process S3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a head positioning method and a disk drive, and more particularly, to a first actuator for performing coarse movement for positioning a head on a target track, and a head for more precisely moving the head to the center of the target track. The present invention relates to a disk device having a second actuator for performing fine movement for positioning and a method for positioning the head thereof.

[0002]

2. Description of the Related Art Conventionally, with the miniaturization of a magnetic disk drive and the diameter of a magnetic disk, the difference between the inner and outer peripheries of the yaw angle, which is the angle formed by a magnetic head and a track tangent, has increased. If the yaw angle differs between the inner and outer circumferences, the magnitude of the reproduced signal or the recorded signal changes between the inner and outer circumferences. For example,
JP-A-6-187624 discloses a technique in which a head slider is swung between a magnetic head slider and a head support arm for the purpose of correcting a change in yaw angle and reducing a yaw angle loss of a reproduced signal. A hinge part supported as possible,
A method including a piezoelectric element that drives the hinge is disclosed.

In Japanese Patent Laid-Open No. 6-314479, a slider position is detected in accordance with a value of a reference counter based on a track crossing pulse generated each time a head passes a track, and a slider position is detected in accordance with the slider position. It is disclosed that the yaw angle is adjusted by adjusting the yaw angle.

[0004]

However, Japanese Patent Application Laid-Open No. 6-314479 does not disclose how to specify a yaw angle corresponding to the position of a slider. Even if a mechanism for correcting the angle exists, a control method for optimally controlling the angle has not been solved yet.

On the other hand, Japanese Patent Application Laid-Open No. H11-16138 discloses a method in which recording tracks on a magnetic disk are grouped into a plurality of track radii and the yaw angle is corrected for each group. . In the yaw angle correction for each group, since the actual yaw angle in the group is deviated, the yaw angle correction cannot be performed with the accuracy inherent in the piezo actuator, for example. When the track following control is performed together with the correction, it may be assumed that the yaw angle becomes too large at the end of the group or the like, and it becomes impossible to obtain a stable detection signal.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a head positioning method and apparatus capable of improving the disadvantages of the prior art and stabilizing the recording and reproducing signal levels.

[0007]

Therefore, according to the present invention, there is provided a head for recording / reproducing data on / from a recording medium, an actuator for fine movement for varying the yaw angle of the head, a head supporting means for supporting the head, A head positioning method for positioning a head using a disk device having a coarse movement actuator for rotating a head support means in a substantially radial direction of the recording medium, wherein a target is set in accordance with an I / O request from a host device. A target track position calculating step of calculating a track position, a coarse movement positioning step of driving the coarse movement actuator toward the target track position calculated in the target track position calculating step, and a target track position calculating step. When the calculated target track position is calculated, the target yaw of the head is determined based on the target track position. A target yaw angle calculation step of calculating the angular, and a fine positioning step of driving the head to the target yaw angle in parallel with the coarse positioning step,
The configuration is adopted. This aims to achieve the above-mentioned object.

In the target track position calculating step, in response to a write / read request (I / O request) from a higher-level device, a track for storing or reading the required data is specified and output as a target track position. I do. Subsequently, in the coarse movement positioning step, the head is moved toward the target track position by controlling the drive of a coarse movement actuator such as a voice coil motor in accordance with the target track position. On the other hand, in the target yaw angle calculation step, using the target track position and another predetermined constant,
The optimum target yaw angle at the target track position is calculated. When the target yaw angle is calculated, in the fine movement positioning step, the head is rotated to the target yoke angle by controlling the drive of a fine movement actuator such as a piezo actuator in parallel with the operation of the head support means in the coarse movement positioning step. Generally, since fine positioning is completed at a higher speed than coarse positioning, after the head is set to the target yoke angle in the fine positioning step, when positioning of the head on the target track in the coarse positioning step is completed. When the head reaches the target track position, the head is at the target yoke angle.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a flowchart showing operation steps of the head positioning method according to the present embodiment. FIG. 2 is a block diagram showing a configuration example of a disk device suitable for implementing this flowchart. FIG. 2 discloses a configuration on which the present embodiment is based. That is, the disk device includes a head 14 for recording and reproducing data on and from the recording medium 15, a fine movement actuator 12 for changing a yaw angle α of the head 14, a head supporting means 33 for supporting the head 14, This head support means 33
And a coarse movement actuator 12 for rotating the recording medium 15 in a substantially radial direction of the recording medium 15. When a magnetic disk is used as the recording medium 15, the head 14 is a magnetic head 14 that converts an electric signal and a magnetic signal. The fine movement actuator 12 changes the yoke angle α of the magnetic head 14 using, for example, the piezoelectric effect of a piezo element.
The yoke angle α is an angle formed between the tangent of the track and the center direction of the magnetic head.

In this embodiment, the magnetic head 14 is positioned while maintaining the yoke angle α at an optimum value by using a disk device having the coarse movement actuator 13 and the fine movement actuator 12 as shown in FIG. First, the host device 3
When an I / O request from 0 is received (step S1), a target track position is calculated according to the I / O request (step S2, target track position calculation step). Subsequently, the coarse movement actuator is driven toward the target track position calculated in the target track position calculation step (step S3, coarse movement positioning step). Before and after the start of driving of the coarse actuator, when the target track position calculated in the target track position calculating step S2 is calculated, the target yaw angle α of the head is calculated based on the target track position (step). S4, target yaw angle calculation step). Further, the head is driven to the target yaw angle in parallel with the coarse movement positioning step S3 (step S3).
5, fine movement positioning step).

As described above, in the present embodiment, since the coarse movement positioning and the yoke angle optimization are performed in parallel, the probability that the yoke angle has already been optimized when the magnetic head 14 is located at the target track. Is high. Further, since the yoke angle is calculated based on the target track position, recording or reproduction can be performed at the yoke angle optimized for each track, and no signal degradation occurs.

In the example shown in FIG. 1, following the setting of the yoke angle S5, it is confirmed whether or not the magnetic head 15 has been positioned on the target track (step S6). Based on the position error signal based on the above, the yoke angle is finely adjusted (follow-up control step). At this time, since the fine adjustment is performed from the optimized state, the yoke angle does not greatly change. If the tracking succeeds, the I / O processing for the recording medium 15 is performed. In this I / O processing, only fine adjustment for following from the optimized yoke angle α is performed. Therefore, even if the yoke angle is slightly changed, the level of the recording / reproducing signal is affected in a high-density medium. There is no.

FIG. 2 shows a disk drive 3 according to this embodiment.
2 is a block diagram illustrating a configuration example of FIG. Disk device 32
Is a head 14 for recording and reproducing data on a recording medium 15
A fine movement actuator 12 for varying the yaw angle of the head 14, a head supporting means 12 for supporting the head 14, and the head supporting means 12
5, a coarse movement actuator 13 for rotating in a substantially radial direction, a positioning control means 34 for driving the fine movement actuator and the coarse movement actuator according to an I / O request from a higher-level device, and an interface for the higher-level device 30; The recording / reproducing signal is transmitted to the host device 30 and the head 1
And a recording / reproducing control unit 21 for transferring data to / from the recording medium.

Further, the positioning control means 34 calculates a target track position in response to an I / O request from the host device 30, and controls the coarse movement positioning control section 9 to drive and control the coarse movement actuator to the target track position. A target yaw angle calculator 4 for calculating a target yaw angle of the head 14 based on the target track position, and a target yaw angle calculator 4
Fine-motion positioning control unit 8 that drives and controls the fine-movement actuator 12 up to the target yaw angle calculated by
And

The recording / reproducing control unit 21 receives an I / O signal from the host device.
Upon receiving the O request, a track for positioning the head is specified based on the storage destination address or the read address of the I / O requested data, and the target track is used as the target track to set the target yaw angle calculation unit 4 and the coarse movement positioning control unit. 9 is output. The target yaw angle calculator 4 calculates the yaw angle of the target track as the target yaw angle based on the target track and other constants. The target yaw angle is a correction amount with respect to the reference position of the head.

When the target track position is specified, the distance d (r) from the center position of the recording medium 15 to the track is determined.
Is specified. Then, when considering a triangle consisting of the intersection point H of the head 14 and the target track, the rotation center point S of the recording medium 15, and the rotation center point V of the head support means, the length R, which is VH, is SV. The length L is specified in advance when designing the disk device. When the triangle HSV is divided into two triangles by a tangent to the target track, R and L
And d (x) can be used to determine α using the second cosine theorem (see FIG. 5).

Also, when designing a disk drive, ΔHSV
And あ る HVS, which are uniquely determined for each track, can be calculated in advance when designing a disk assembly. Then, when the triangle HSV is divided into two triangles by a tangent to the target track, α can be obtained from γ and β. In this way, a plurality of predetermined constants and a target track (or
Using the distance from the center of rotation of the recording medium to the track in the radial direction), the yaw angle α can be calculated for each track. Therefore, the yaw angle does not change in each track, and in particular, since the yaw angle can be made substantially the same between the inner and outer peripheral sides and the center position, the stability of the recording / reproducing signal over the entire circumference of the disk can be maintained. Can be kept at a certain level.

[0018]

First Embodiment Next, a first embodiment of the present invention will be described with reference to FIG. In the example shown in FIG. 3, a magnetic disk device is employed as the disk device. Therefore, head 1
Reference numeral 4 denotes a magnetic head, and the recording medium 15 is a magnetic disk. In the first embodiment, the yaw angle correction signal obtained from the target track is added to the positioning control signal of the piezo actuator 8 serving as the fine movement actuator, and
The change in the yaw angle of 4 is corrected, and positioning is accurately performed on a predetermined positioning track.

Referring to FIG. 5, the magnetic disk drive according to this embodiment includes a voice coil motor (VCM) 13 as a coarse actuator, a piezo actuator 12 as a fine actuator, and a magnetic head 14. . The magnetic disk drive further includes a positioning control CPU1 operating as positioning control means, and a positioning control signal 1 output by the positioning control CPU1.
D / A converter 6, which converts 9, 19 into analog data
7, a piezo drive amplifier 8 for amplifying a piezo actuator drive signal 18 for the piezo actuator 12 and outputting the signal to the piezo actuator, and a VCM drive amplifier 9 for amplifying a voice coil motor drive signal 19 for the voice coil motor.

In the example shown in FIG.
5, a position error signal generator 10 for outputting an amount of displacement (offset) of the head with respect to the track based on the burst signal recorded in 5, and an A for converting the position error signal into digital data and outputting it to the positioning control CPU. / D converter.

The positioning control CPU 1 calculates a yaw angle corrector (a target yaw angle) that calculates a rotation angle at which the yaw angle becomes zero when the magnetic head is rotated on the target track according to the target track. A calculation unit) 4, a piezo drive signal calculator (fine movement positioning control unit) 2 for generating a piezo drive signal according to the position error signal, and a drive amount of the voice coil motor corresponding to the target track is calculated as a VCM drive signal. VCM drive signal computing unit (coarse positioning controller)
3 is provided.

Next, the operation of the first embodiment will be described.

The magnetic head 14 includes a magnetic disk medium 15
The servo information (not shown) written above is read and a servo signal 22 is output. The position error signal generation circuit 10 receives the servo signal 22 and outputs a position error signal 23. The A / D converter 11 receives the position error signal 23 and outputs a discretized position error signal. The yaw angle corrector 4 in the positioning control CPU 1 calculates a yaw angle correction amount from a target track specified by a host device (not shown) and outputs a yaw angle correction signal. Positioning control CPU
The piezo drive signal calculator 2 in 1 receives the discretized position error signal and outputs a piezo actuator drive signal 16 as a positioning control signal so that positioning can be performed on a target track specified by the host device. .

The VCM drive signal calculator 3 in the positioning control CPU 1 receives the piezo drive signal 16 and outputs a VCM drive signal 19 as a positioning control signal so as to perform positioning on a target track specified by the host device. I do.
The piezo drive signal calculator 2 and the VCM drive signal calculator 3
The output signal is obtained by phase lead / lag compensation, PID compensation, closed loop control by an optimal regulator, and the like. The adder 5 in the positioning control CPU 1 receives the piezo actuator drive signal 16 and the yaw angle correction signal 17 and outputs a piezo actuator drive signal 18 with the yaw angle corrected. The D / A converter 6 receives the piezo actuator drive signal 18 with the yaw angle corrected, and outputs a piezo actuator drive signal that is an analog quantity.

The D / A converter 7 receives the VCM drive signal 19 and outputs a VCM drive signal which is an analog quantity.
The piezo drive amplifier 8 inputs a piezo actuator drive signal of an analog amount and outputs a piezo actuator drive current 20. The VCM drive amplifier 9 receives a VCM drive signal, which is an analog amount, and outputs a VCM drive current 21. The VCM 13 receives the VCM drive current 21, moves the carriage to which the magnetic head 14 is attached at the tip, and performs positioning on the target track specified by the host device. The piezo actuator 12, which is an actuator for fine movement, receives the piezo actuator drive current 20, moves the magnetic head 14 at the leading end of the carriage, and performs precise positioning using the target track specified by the host device.

FIG. 4 is an explanatory diagram for performing a geometric definition for calculating the target yaw angle. As shown in FIG. 4, the rotation center point of the magnetic disk medium 15 is represented by S, the rotation center of the voice coil (VCM) 13 is represented by V, and the drive point of the piezo actuator 12 is represented by H. The intersection of a straight line (tangent line of the target track) perpendicular to the straight line SH and the straight line SV is indicated by a point P.
And

Here, the yaw angle α is represented by a straight line P
It is determined as the angle formed by the extension of H and the extension of the straight line VH (hence α = ∠VHP). If the magnetic head 14 can be moved so that the yaw angle α becomes constant (or zero), the recording and reproducing sensitivity of the magnetic head 14 can be increased, and the recorded data on the magnetic disk medium 15 can be accurately recorded and reproduced. It becomes possible.

On the other hand, in the right-angled triangle HSP, since the sum of the interior angles of the triangle is 2π, ΔHPS = π / 2−γ
It is. Therefore, focusing on the triangle HPV, the following equation (3) holds. On the other hand, Equations (4) and (5) are established from the second cosine theorem which determines the angle of each angle from the length of each side of the triangle using the Pythagorean theorem. Since the angles β and γ can be expressed as arc cosine functions, the following equation (1) holds for the yaw angle α with d (x) as the only variable. The yaw angle corrector 4 calculates and outputs a yaw angle correction signal 17 from equation (4).

[0029]

(Equation 3)

As described above, according to the present embodiment, the position of the drive point of the piezo actuator 12, the position of the drive point of the VCM actuator 13, and the position of the rotation center of the magnetic disk are known, and the equation ( 1) yaw angle α
Can be calculated, and when the head is driven by the yaw angle, data can be recorded and reproduced on the angular target track in a state parallel to the tangent to the track. For this reason, the signal level for recording and reproduction is stabilized.

[0031]

Second Embodiment Next, a second embodiment of the present invention will be described with reference to the drawings. Referring to FIG. 5, a piezo drive signal arithmetic unit 2 in the positioning control CPU 1 receives the discretized position error signal, and is a positioning control signal so that positioning can be performed on a target track specified by the host device. The piezo actuator drive signal 16 is output. The VCM drive signal calculator 3 in the positioning control CPU 1 inputs the discretized position error signal and outputs a VCM drive signal 19 as a positioning control signal so that positioning can be performed on a target track specified by the host device. I do. The yaw angle corrector 4 in the positioning control CPU 1 calculates a yaw angle correction amount from the target track specified by the host device, and outputs a yaw angle correction signal.

Here, the yaw angle corrector 4 outputs a yaw angle correction signal 17 by the same correction method as in the first embodiment. That is, in the magnetic head positioning method of the present invention, the yaw angle correction signal is added to the fine movement actuator drive signal regardless of the fine movement actuator drive method and coarse movement actuator drive method in the positioning control CPU 1. A similar effect can be obtained.

In the first embodiment, the yaw angle is obtained from the second cosine theorem as a calculation method of the yaw angle corrector. However, the second cosine theorem requires an inverse cosine function (Arccosine).
The calculation of the inverse cosine function may increase the processing load, such as increasing the calculation processing time of the positioning control CPU 1. When the calculation error is small, it is possible to reduce the CPU1 calculation processing time by using Expression (2) instead of the inverse function of cosine.

[0034]

(Equation 4)

If cos θ is sufficiently close to 0 in cos θ, it can be calculated as cos θ ≒ −θ + π / 2.
Depending on conditions, the CPU processing time can be further reduced by the above method. By reducing the CPU processing time, yaw angle correction can be performed without deteriorating the positioning accuracy.

As described above, according to this embodiment, since the yaw angle corrector corrects the change in the yaw angle of the magnetic head, the magnetic head can be easily moved.
gle) To be able to position accurately on a predetermined positioning track in a state without displacement. Then
Stable signal reproduction / recording becomes possible, and as a result, the size and density of the disk device can be reduced.

[0037]

The present invention is constructed and functions as described above. According to this, in the target yaw angle calculating step, the target track position and the other predetermined constants are used to optimize the target track position. Is calculated, and then
In the fine movement positioning step, in parallel with the operation of the head support means in the coarse movement positioning step, when the fine movement actuator is drive-controlled to rotate the head to the target yoke angle,
After the head is set to the target yoke angle by the fine movement positioning step, the positioning of the head to the target track by the coarse movement positioning step is completed. Therefore, the level of the signal to be recorded and reproduced does not decrease due to the fluctuation of the yoke angle. Thus, it is possible to provide an unprecedented superior head positioning method capable of obtaining a stable level of a recording / reproducing signal regardless of the difference between the inner and outer circumferences.

[Brief description of the drawings]

FIG. 1 is a flowchart showing an embodiment of the present invention.

FIG. 2 is a block diagram showing an embodiment of the present invention.

FIG. 3 is a block diagram illustrating a configuration of a first exemplary embodiment of the present invention.

FIG. 4 is an explanatory diagram for defining constants and variables used in the configuration shown in FIG. 3;

FIG. 5 is a block diagram showing a configuration of a second exemplary embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Positioning CPU as an example of positioning control means 2 Piezo drive signal calculator 3 VCM drive signal calculator 4 Yaw angle (Yaw angle) corrector 5 Adder 6,7 D / A converter 8 Piezo drive amplifier 9 VCM drive Amplifier 10 Position error signal generation circuit 11 A / D converter 12 Piezo actuator 13 Voice coil motor (VCM) 14 Magnetic head 15 Magnetic disk medium 16 Piezo actuator drive signal 17 Yaw angle correction signal 18 Yaw angle corrected piezo actuator drive signal Reference Signs List 19 VCM drive signal 20 Piezo actuator drive current 21 VCM drive current 22 Servo signal 23 Position error signal 30 Host device 31 Recording / playback control unit 32 Disk device (for example, magnetic disk device) 33 Magnetic head support unit 34 Positioning control means H Drive point of piezo actuator 12 S Rotation center of magnetic disk medium 15 V Rotation center of voice coil (VCM) 13 P Intersection point of straight line SV and straight line orthogonal to straight line L L Center of rotation of magnetic disk medium 15 and voice coil (VCM) ) Distance from rotation center V of 13 R Distance between drive point H of piezo actuator 12 and rotation center V of voice coil (VCM) 13 d (x) Points S and H obtained from target track x specified by the host device Distance α Yaw angle β ∠ HVS γ ∠ HSV

Claims (6)

[Claims] 1. A head for recording / reproducing data on / from a recording medium, an actuator for fine movement for changing a yaw angle of the head, a head supporting means for supporting the head, and a head supporting means for substantially changing the radius of the recording medium A head positioning method for positioning a head using a disk device having a coarse movement actuator that rotates in a direction, the target track position calculating step for calculating a target track position in accordance with an I / O request from a host device A coarse movement positioning step of driving the coarse movement actuator toward the target track position calculated in the target track position calculation step, and a target track position calculated in the target track position calculation step. A target yaw angle calculating step of calculating a target yaw angle of the head based on the target track position at the time. Head positioning method, characterized in that in parallel with the coarse positioning step and a fine positioning step of driving the head to the target yaw angle. 2. Following the fine movement positioning step, the yaw angle of the head that has reached the target yaw angle after being positioned near the target track position in the coarse movement positioning step is again finely moved to follow the track. 2. The head positioning method according to claim 1, further comprising a tracking control step. 3. A head for recording / reproducing data on / from a recording medium, a fine-movement actuator for varying the yaw angle of the head, a head supporting means for supporting the head, and the head supporting means on the recording medium. An actuator for coarse movement that is rotated in a substantially radial direction, and an I / O from a host device
Positioning control means for driving the fine movement actuator and the coarse movement actuator in accordance with a request, wherein the positioning control means calculates a target track position in response to an I / O request from a host device, and sets the target track position to the target track position. A coarse movement positioning control unit that drives and controls a coarse movement actuator, a target yaw angle calculation unit that calculates a target yaw angle of the head based on the target track position, and a target yaw angle calculated by the target yaw angle calculation unit A fine movement positioning control unit for controlling the drive of the fine movement actuator up to the step (b). 4. The target yaw angle calculating section determines a predetermined value from a head rotation center point V which is a rotation center position of the head support means to a medium rotation center point S which is a rotation center position of the recording medium. Length L, a predetermined length R from the head rotation center point V to the drive point H of the fine movement actuator, and the target track from the medium rotation center point S to the drive point H of the fine movement actuator. 4. The disk device according to claim 3, further comprising a function of calculating the target yaw angle α based on a length d (x) that changes according to the position. 5. The target yaw angle calculation unit calculates the target yaw angle according to the following equation (1): 5. The disk device according to claim 4, wherein said α is calculated according to: 6. The target yaw angle calculating section calculates the target yaw angle according to the following equation (2): 5. The disk device according to claim 4, wherein said α is calculated according to: