JP2000182340A - Head positioning device in recording disk device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stably execute magnetic head positioning control by adjusting a control characteristic of a fine moving actuator to become equal to a designed value, executing magnetic head positioning control with high precision and moreover securing a high frequency gain margin to become equal to the designed value. SOLUTION: A gain of a fine moving actuator 12 is measured with a fine moving actuator gain measuring instrument 2. When a measured result exists within a proper range, the measured result is outputted to a magnetic head positioning controller 4. When the gain of the fine moving actuator 12 is measured, a sine wave signal 17 required for measuring is generated from a sine wave generator 3, added to a fine moving actuator driving signal 18 and fed to the fine moving actuator 12. Consequently, a positional error signal from a positional error signal generating circuit 10 is measured with the fine moving actuator gain measuring instrument 2. A gain of a controller is adjusted with the magnetic head positioning controller 4 in accordance with an output value of the fine moving actuator gain measuring instrument 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a head positioning device in a magnetic disk drive or the like, and more particularly, to a coarse actuator for positioning a head on a target track, and more precisely to the center of the target track than the coarse actuator. The present invention relates to a head positioning apparatus having a fine movement actuator for performing

[0002]

2. Description of the Related Art Conventionally, as a head positioning device of this type of magnetic disk drive, for example, Japanese Patent Laid-Open No. 2-227
As shown in Japanese Patent Publication No. 886, it is used for positioning a head on a target track with high accuracy.

FIG. 2 is a block diagram showing an example of such a conventional magnetic disk drive head positioning device. The magnetic disk drive includes a CPU 1 for controlling the positioning of a magnetic head 14 and a voice coil motor (V) as a coarse movement actuator for coarsely controlling the magnetic head 14.
A CM) 13, a VCM drive amplifier 9 for driving and controlling the VCM 13, a piezo actuator 12 which is a fine movement actuator for finely controlling the magnetic head 14,
A piezo drive amplifier 8 for driving and controlling the piezo actuator 12 and a digital drive signal 1 from the CPU 1
D / A converters 6 and 7 for converting analog signals 8 and 19 into analog signals and supplying the analog signals to respective amplifiers 8 and 9, and a position error signal generation for generating a position error signal by inputting a servo signal 22 from magnetic head 14 It has a circuit 10 and an A / D converter 11 which converts an analog position error signal 23 from the position error signal generation circuit 10 into a digital signal and supplies the digital signal to the CPU 1.

The CPU 1 has a magnetic head positioning controller 4 for controlling the values of drive signals 18 and 19 based on the position error signal. The magnetic heads 14 are respectively attached to the distal ends of a pair of carriages 30 constituting a recording head assembly arranged in an arm shape on the upper and lower surfaces of the magnetic disk 15, and are scanned by magnetic tracks on the upper and lower surfaces of the magnetic disk 15. It has become so. And
The VCM 13 is provided on the base end side of the carriage 30,
The magnetic head 14 is roughly moved by controlling the movement of the entire recording head assembly. Further, the piezo actuator 12 is disposed in the middle of the carriage 30, and the magnetic head 14
Is to make slight movements. Also, the magnetic disk 15
It is held by a spindle motor 31 which is a disk drive unit, and is rotationally driven and controlled.

Next, a description will be given of a head positioning operation in the magnetic disk drive having the above-described configuration. The magnetic head 14 reads servo information (not shown) written on the magnetic disk 15 and outputs a servo signal 22. The position error signal generation circuit 10
4 and a position error signal 23 is output. The A / D converter 11 receives the position error signal 23 and outputs a discretized position error signal. The magnetic head positioning controller 4 in the positioning control CPU 1 inputs the discretized position error signal and outputs the signal to the host device (not shown).
Actuator driving signal 1 which is a positioning control signal so that positioning can be performed on the target track designated by
8 and the VCM drive signal 19 are output. The magnetic head positioning controller 4 performs phase lead / lag compensation and PID (Prop
The drive signals 18 and 19 are determined by compensation or closed loop control using an optimal regulator.

[0006] The D / A converter 6 receives a piezo actuator drive signal 18 and outputs a piezo actuator drive signal, which is an analog quantity, to the piezo drive amplifier 8. The piezo drive amplifier 8 inputs a piezo actuator drive signal of an analog amount and outputs a piezo actuator drive current 20 to the piezo actuator 12 which is a fine movement actuator. The D / A converter 7 has a VCM
The drive signal 19 is input, and a VCM drive signal, which is an analog amount, is output to the VCM drive amplifier 9. The VCM drive amplifier 9 receives a VCM drive signal, which is an analog amount, and outputs a VCM drive current 21. VCM13 is V
The CM drive current 21 is input, the carriage 30 having the magnetic head 14 attached to the tip is moved, and positioning is performed on a target track designated by a host device (not shown). The piezo actuator 12 receives the piezo actuator drive current 20, moves the magnetic head 14 at the tip of the carriage 30, and performs more precise positioning on a target track specified by a higher-level device (not shown).

[0007]

However, in the above-mentioned prior art, since the characteristics of the actuator for fine movement are different from the design, a sufficient frequency band for control cannot be secured, and the positioning accuracy in the magnetic head positioning control is low. There is a problem that it becomes worse than the estimate at the time of design. In addition, since the characteristics of the actuator for fine movement are different from those of the design, the gain margin in the high frequency band is reduced, so that there is a problem that the stability of the control system in the magnetic head positioning control is worse than the estimate at the time of design.

It is an object of the present invention to adjust the control characteristics of the actuator for fine movement so as to be equal to the design value, and to accurately control the positioning of the recording head. Another object of the present invention is to adjust the control characteristics of the fine movement actuator so as to be equal to the design value, secure a high-frequency gain margin equal to the design value, and stably perform the recording head positioning control. It is in.

[0009]

According to the present invention, there is provided a disk drive for holding and rotating a recording disk and transferring a recording head to the recording disk held by the disk drive. A recording head assembly for supporting the recording head, a coarse actuator for driving the recording head assembly to position the recording head at a target track, and positioning the recording head at the center of the target track more precisely than the coarse actuator. A head positioning device for a recording disk device having a fine-movement actuator for causing the fine-movement actuator to measure a gain of the fine-movement actuator, and an adjustment means for adjusting a control characteristic of the fine-movement actuator based on a measurement result of the measurement means. It is characterized by having.

In the head positioning device for a recording disk device of the present invention, the measuring means measures the gain of the fine movement actuator and outputs the measurement result to the adjusting means.
The adjusting means adjusts the control characteristic of the fine movement actuator gain so as to become equal to a design value by adjusting the control characteristic of the fine movement actuator based on the measurement result of the measuring means, and performs the magnetic head positioning control with high accuracy. Specifically, the measuring means inputs a position error signal from the recording head and a drive signal of a fine movement actuator for positioning the recording head on the target track when the recording head is driven in a vibrating state, Measure the gain of the fine movement actuator. The recording head is driven in a vibrating state, for example, by adding a sine wave signal by a sine wave generating means to a drive signal of a fine movement actuator and supplying the signal. The measuring means determines whether or not the measurement result of the gain of the fine movement actuator is within an appropriate range.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a head positioning device for a recording disk device according to the present invention will be described below. FIG. 1 is a block diagram showing an example of a head positioning device of a magnetic disk drive according to a first embodiment of the present invention. Note that the same elements as those in the configuration shown in FIG.

In the present embodiment, the gain of the fine movement actuator (piezo actuator 12) is measured, and if the measured result is within the appropriate range of the fine movement actuator gain, the fine movement is output to the magnetic head positioning controller 4. Actuator gain measuring device 2. In addition, the magnetic head positioning controller 4 adjusts the gain of the piezo drive amplifier 8 according to the output value of the actuator gain for fine movement. A sine wave generator 3 for generating a sine wave signal necessary for measuring the fine movement actuator gain;
It has an adder 5 for adding the actuator drive signal for fine movement and the sine wave signal. With such a configuration, the control characteristics of the fine movement actuator can be adjusted to be equal to the design value, and the magnetic head positioning control can be performed with high accuracy. An object of the present invention is to provide a head positioning device capable of performing positioning control stably.

Next, a specific configuration of the present embodiment will be described in detail with reference to FIG. The magnetic disk drive of the present embodiment has a CPU 1 that controls the positioning of the magnetic head 14.
A voice coil motor (VCM) 13 which is a coarse movement actuator for coarsely controlling the magnetic head 14;
A VCM drive amplifier 9 for driving and controlling the CM 13; a piezo actuator 12 as a fine movement actuator for finely controlling the magnetic head 14; a piezo drive amplifier 8 for driving and controlling the piezo actuator 12;
The D / A converters 6 and 7 that convert the digital drive signals 18 and 19 from the PU 1 to analog signals and supply the analog signals to the amplifiers 8 and 9 and the servo signal 22 from the magnetic head 14 and input the position error signal Generating position error signal generating circuit 10
And an A / D converter 11 that converts an analog position error signal 23 from the position error signal generation circuit 10 into a digital signal and supplies the digital signal to the CPU 1.

CPU 1 measures the magnetic head positioning controller 4 for controlling the values of drive signals 18 and 19 based on the position error signal, and measures the gain of piezo actuator 12 based on a signal from position error signal generating circuit 10. A fine movement actuator gain measuring device 2, a sine wave generator 3 for generating a sine wave signal 17 necessary for measuring the fine movement actuator gain, and a fine movement actuator drive signal 18
And an adder 5 for adding the sine wave signal 17. The magnetic heads 14 are attached to the distal ends of a pair of carriages 30 constituting a recording head assembly arranged in an arm shape on the upper and lower surfaces of the magnetic disk 15, respectively, and are scanned by magnetic tracks on the upper and lower surfaces of the magnetic disk 15. It has become so. The VCM 13 is provided on the base end side of the carriage 30 and moves the magnetic head 14 roughly by controlling the movement of the entire recording head assembly. The piezo actuator 12 is arranged in the middle of the carriage 30 and finely moves the magnetic head 14 by minute deformation of the carriage 30. The magnetic disk 15 is held by a spindle motor 31 which is a disk drive unit, and is rotationally controlled.

Next, a description will be given of a head positioning operation in the magnetic disk device having the above-described configuration. The magnetic head 14 reads servo information (not shown) written on the magnetic disk 15 and outputs a servo signal 22. The position error signal generation circuit 10 receives the servo signal 22 and outputs a position error signal 23. A / D
The converter 11 receives the position error signal 23 and outputs a discretized position error signal. The piezo actuator gain measuring device 2 in the positioning control CPU 1 outputs a sine wave signal 17 to a discrete position error signal output from the A / D converter 11 and a piezo actuator driving signal 18 output from the adder 5. Is input, and a piezo actuator gain signal 16 is output.

When a piezo actuator gain measurement command is issued from a higher-level device (not shown), a sine wave signal
Is output, and the sine wave signal 17 is not output when the measurement command is not issued. A magnetic head positioning controller 4 in the positioning control CPU 1 receives the discretized position error signal and performs a piezo positioning control signal so as to perform positioning on a target track designated by a higher-level device (not shown). An actuator drive signal 18 and a VCM drive signal 19 are output. The magnetic head positioning controller 4 obtains the drive signals 18 and 19 by phase lead / lag compensation, PID compensation, closed loop control by an optimal regulator, and the like. When the piezo actuator gain signal 16 is output from the piezo actuator gain measurement device 2 when the piezo actuator gain measurement command is issued, the magnetic head positioning controller 4 The gain in the controller is adjusted so that the control characteristics of No. 12 become equal to the design values. The adder 5 in the positioning control CPU 1 receives the sine wave signal 17 and the piezo actuator drive signal 18 and outputs a piezo actuator drive signal including a sine wave.

The D / A converter 6 receives the piezo actuator drive signal 18 and outputs a piezo actuator drive signal which is an analog quantity. The D / A converter 7 has a VC
An M drive signal 19 is input and a VCM drive signal, which is an analog amount, is output. 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. VCM13 is V
The CM drive current 21 is input, the carriage 30 having the magnetic head 14 attached to the tip is moved, and positioning is performed on a target track specified by a host device (not shown). The piezo actuator 12 receives the piezo actuator drive current 20 and moves the magnetic head 14 at the tip of the carriage 30 to perform more precise positioning on a target track specified by a host device (not shown).

Next, FIG. 3 is a flowchart showing the operation of the head positioning apparatus of the present embodiment, and FIG. 4 is an explanatory diagram showing an arithmetic expression used in the head positioning processing of the present embodiment. Hereinafter, description will be made with reference to FIGS. Piezo actuator gain measuring device 2 in positioning control CPU 1
Checks whether a piezo actuator gain measurement command has been issued from the host device (step A1). And
When the piezo actuator gain measurement command is issued, the piezo actuator gain measuring device 2 measures the piezo actuator gain (step A2). That is, in step A2, the sine wave signal 17 having the frequency f [Hz] is added to the piezo actuator drive signal 18 as noise by the sine wave generator 3. In the vibrating state of the piezo actuator 12, the added piezo actuator drive signal I _PZT output from the adder 5 and the A / D
Discretized position error signal x output from converter 11
_{and pes} are _subjected to Fourier transform, and a piezo actuator gain K _PZT is obtained from equation (1) shown in FIG. In equation (1), ω = 2πf [rad / sec].

Thereafter, when the measurement of the piezo actuator gain is completed, the piezo actuator gain measuring device 2
Checks whether the measurement result of the piezo actuator gain is within an appropriate range (step A3). Here, when the piezo actuator gain is within the appropriate range, the piezo actuator measuring device 2 outputs a piezo actuator gain signal 16 which is a measurement result of the piezo actuator gain to the magnetic head positioning controller 4 (step A).
4). If the piezo actuator gain is not within the appropriate range, the piezo actuator gain signal 16 is not updated as a measurement value abnormality (step A5).

Next, a second embodiment of the present invention will be described. FIG. 5 is a block diagram showing an example of a head positioning device of a magnetic disk drive according to the second embodiment of the present invention. Note that the same components as those in the configuration shown in FIG. In the present embodiment, the sine wave signal 17 is added to both the piezo actuator drive signal 18 and the VCM drive signal 19, which are the outputs of the magnetic head positioning controller 4. Therefore, the sine wave signal 17 is added to the VCM drive signal 19, but the sine wave signal 17 is added to the position error signal obtained by discretizing the signal input to the piezo actuator gain measuring device 2 and the piezo actuator drive signal 18. Since the signal is obtained, the piezo actuator gain K _PZT can be measured as in the first embodiment.

In each of the above embodiments, the sine wave generator 3 is formed in the positioning control CPU 1. However, for example, a sine wave signal table is created in a semiconductor memory device or the like, and the semiconductor memory device or the like is prepared. To positioning control CPU
1 may obtain sine wave signal information. Further, in each of the above embodiments, the sine wave signal 17 of one frequency f [Hz] is used as noise by the sine wave generator 3 for measurement. However, as shown in the equation (2) shown in FIG. Alternatively, the measurement may be performed based on the individual frequencies and the average may be obtained.
As described above, by measuring at N frequencies, the measurement accuracy of the piezo actuator gain K _PZT can be improved. Further, the present invention is not limited to a magnetic disk device, and can be applied to a head positioning device of another recording disk device.

[0022]

As described above, in the head positioning device of the recording disk device of the present invention, the gain of the fine movement actuator for controlling the fine movement of the recording head is measured, and the control characteristic of the fine movement actuator is adjusted from the measurement result. I did it. Therefore, the gain of the fine movement actuator can be adjusted to be equal to the design value to compensate for the control characteristics, and the recording head can be positioned more precisely. Further, the gain of the fine movement actuator is adjusted to be equal to the design value, the gain margin in the high frequency range can be secured equal to the design value, and the recording head positioning control can be stably performed.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an example of a head positioning device of a magnetic disk drive according to a first embodiment of the present invention.

FIG. 2 is a block diagram illustrating an example of a conventional head positioning device for a magnetic disk drive.

FIG. 3 is a flowchart showing an operation of the head positioning device shown in FIG.

FIG. 4 is an explanatory diagram showing an arithmetic expression used in the embodiment of the present invention.

FIG. 5 is a block diagram showing an example of a head positioning device of a magnetic disk drive according to a second embodiment of the present invention.

[Explanation of symbols]

1. Positioning CPU 2. Fine movement actuator gain measuring device 3. Sine wave generator 4. Magnetic head positioning controller 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, 30 ... carriage, 31 ...
Spindle motor.

Claims (9)

[Claims] 1. A disk drive unit that holds and rotates a recording disk and drives the recording disk, a recording head assembly that supports a recording head that can be transported to the recording disk held by the disk drive unit, and a recording head assembly that A head of a recording disk device comprising: a coarse actuator for driving to position the recording head on a target track; and a fine actuator for positioning the recording head at the center of the target track more precisely than the coarse actuator. A positioning device, comprising: measuring means for measuring a gain of the fine movement actuator; and adjusting means for adjusting a control characteristic of the fine movement actuator from a measurement result of the measuring means. Positioning device. 2. The apparatus according to claim 1, wherein the measuring means receives a position error signal from the recording head and a driving signal for a fine movement actuator for positioning the recording head on a target track when the recording head is driven in an excited state. 2. The head positioning device for a recording disk device according to claim 1, wherein the gain of the actuator is measured. 3. A head positioning apparatus for a recording disk device according to claim 2, further comprising frequency signal generating means for generating a frequency signal for driving said recording head in a vibrated state. 4. The head positioning device according to claim 3, wherein the frequency signal is a sine wave signal. 5. The frequency signal generating means generates a plurality of frequency signals, and the measuring means measures a gain when the recording head is driven in a vibrating state at a plurality of frequencies. Item 4. A head positioning device for a recording disk device according to Item 3. 6. The frequency signal generating means according to claim 3, wherein said frequency signal generating means is means for storing frequency information in a storage element in advance, and reading frequency information from said storage element to generate a frequency signal. Head positioning device for recording disk devices. 7. The apparatus according to claim 1, wherein said measuring means includes a judging means for judging whether a measurement result of a gain of said fine movement actuator is within an appropriate range. Head positioning device for recording disk devices. 8. The micro-movement actuator according to claim 1, wherein the recording head assembly is minutely deformed by a piezo element.
Item 7. A head positioning device for a recording disk device according to Item 1. 9. The head positioning device for a recording disk device according to claim 1, wherein said coarse movement actuator displaces the entire recording head assembly by a voice coil motor. .