JP2002251858A - Disk device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a disk device capable of performing stable positioning control even if the disk device is vibrated and impacted. SOLUTION: The disk device is provided with a means 10 for driving an actuator 9 of a magnetic head 2, a voltage detection means 11 for outputting a voltage signal Va generated in driving the actuator, a speed load estimation means 12 for outputting a speed estimation signal vest of the head and a load estimation signal τdest of the actuator from a driving signal u and the voltage signal Va, a speed control means 14 for generating a speed control signal cv, a position detection means 16 for generating an error signal ex corresponding to the present position of the head, a position control means 17 for generating a position control signal cx, a corrector 15 for outputting a driving signal u from the load estimation signal τdest and the control signal c, a selection means 18 for selecting either the speed control signal cv or the position selection signal cx, and a level detector 19 for outputting a change-over signal to the selection signal 19 for outputting the change-over signal to the selection means according to the size of the load estimation signal τddest .

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a disk drive having a load / unload mechanism for loading a head onto a disk surface by an actuator and unloading the disk from the disk surface.
The reproducing head can be positioned to a desired position of a target track of a disk as a recording medium with high accuracy by an actuator, and the head and the disk collide with the disk due to external impact or vibration during the positioning operation. The present invention relates to a disk device configured to prevent damage.

[0002]

2. Description of the Related Art In recent years, the size and capacity of magnetic disk drives have been rapidly increasing. In a conventional magnetic disk drive, a contact start / stop (CSS) method is employed. In these CSS type disk devices,
When the disk is stopped and not operating, the head slider on which the head is mounted lands on a retreat area formed outside the data area on the disk surface. Therefore, CS
In the S-type magnetic disk drive, there is a danger that the head slider moves to the data area due to an impact, damaging the disk surface, or being attracted to the disk data area surface.

For the purpose of avoiding such danger and increasing the reliability during non-operation, a disk drive having a head load / unload mechanism has been developed. This is because a ramp block is arranged outside the outer peripheral edge of the disk, and when the operation of the disk device is stopped, the arm is rotated so that the suspension tab of the arm is placed on the tab holding surface of the ramp block. Is to be unloaded. When the disk drive starts operating, the head arm is rotated to load the head slider from the ramp block onto the rotating disk.

A feature of the load / unload type magnetic disk device is that the head slider is retracted onto the ramp block when not operating, so that the head slider does not stick to the surface of the disk data area when the disk stops. Therefore, since a disk having a smoother surface can be used, higher density recording can be realized.
In addition, since the head is retracted from the disk, it is characterized in that the shock resistance during non-operation can be improved.

On the other hand, in a load / unload type magnetic disk drive, if the loading speed of the head is too high, the head slider collides with the disk and damages the disk or the head. It is necessary to ascend smoothly. Therefore,
In order to smoothly load the head on the disk, it is necessary to perform stable speed control even on the ramp block.

In order to improve the reliability of load / unload, a conventional load / unload type disk device uses a voice coil motor (VCM) as an actuator for driving a head. In addition, an induced voltage generated at both ends of the VCM coil is detected by a bridge circuit, and feedback speed control is performed using the obtained detected voltage as a speed signal (for example, Japanese Patent Application Laid-Open No.
No. 25626).

[0007] To increase the capacity of the magnetic disk drive,
As the track density of the magnetic disk increases, the track pitch tends to be narrower. Therefore, in order to record / reproduce data on / from the magnetic disk, it has become necessary to position the magnetic head with high accuracy on a target track formed with a narrow track pitch.

In a conventional magnetic disk drive, servo information is previously formed on a magnetic disk in order to position the magnetic head, and the positioning of the magnetic head is controlled according to the servo information. That is, by reading the servo information with the magnetic head, an error signal indicating a position error of the magnetic head with respect to the target track is generated, and the positioning of the magnetic head is controlled so that the error signal is minimized. Therefore, in order to improve the positioning accuracy of the magnetic head, the control frequency of the positioning control system of the magnetic head is set to be high, and the magnetic head is quickly positioned on the target track to secure the necessary positioning accuracy.

However, there are cases where a higher-order natural mechanical resonance exists in the actuator itself of the positioning mechanism. If the control frequency is increased to increase the positioning accuracy, the positioning control system becomes unstable due to the natural mechanical resonance. Problem. Therefore, the band of the control frequency is actually limited by the inherent mechanical resonance of the actuator itself, and there is a limit to increasing the control frequency of the positioning control system. Therefore, in order to increase the positioning accuracy of the magnetic head, an external force acting on the actuator, which is a factor that deteriorates the positioning accuracy, has been reduced.

In addition, due to the recent increase in track density and reduction in the size and weight of the actuator, the external force acting on the actuator greatly affects the positioning control system. In addition, with the miniaturization and high recording density of magnetic disk drives, the demand for high-precision positioning of magnetic heads has become strict. On the other hand, in these magnetic disk drives, external forces themselves have been compensated by feedforward control. ing.

For example, a method has been proposed in which a head position signal is obtained from servo information recorded on a magnetic disk, and external force is compensated by external force estimating means which receives the head position signal and a VCM drive signal as an actuator as inputs. (See, for example, JP-A-9-231701).

[0012]

However, in the above-mentioned prior art, the head is retracted from the disk during non-operation, so that the shock resistance during non-operation can be improved. If a shock or vibration is applied during data recording / reproducing on the top, the magnetic head jumps on the disk surface, and when the magnetic head hits the disk, there is a problem that the head and the disk are damaged. .

In the above-mentioned prior art, the speed signal required for performing the feedback speed control of the head moving speed is represented by V, which is an actuator for driving the head.
The induced voltage generated in the VCM coil when the CM rotates is used. In order to detect the induced voltage, generally V
A bridge circuit having a CM coil on one side is used. Therefore, although the circuit configuration is simple, there is a problem in that the disturbance moving load generally fluctuates greatly due to the sliding friction between the suspension tab and the tab holding surface on the ramp block, so that the head moving speed fluctuates greatly. Therefore, there is a problem that the head loading speed is largely fluctuated when the feedback control of the head moving speed is performed, and there is a risk that the slider collides with the disk.

In recent years, magnetic disk devices are often mounted on portable computers and the like, and such portable devices are susceptible to external vibrations and shocks.
It is extremely difficult for the magnetic disk drive to keep a high-precision positioning state and follow the target track against such vibrations and shocks, and to prevent damage to the head and disk from externally applied shocks and vibrations. Met.

SUMMARY OF THE INVENTION In view of the above problems, the present invention accurately detects the moving speed of a head and, at the same time, compensates for an external force such as friction acting on an actuator to thereby reduce friction on a head retreating member such as a ramp block. It is an object of the present invention to provide a disk device capable of performing stable speed control even when load fluctuation is large.

Further, according to the present invention, a head is smoothly loaded on a disk by switching completely different controls between a moving speed control of a head and a positioning control to a target track in response to a switching command, and then a narrow track is controlled. It is an object of the present invention to provide a disk device capable of performing high-accuracy positioning control of a head with respect to a target track formed at a pitch.

Another object of the present invention is to provide a highly reliable disk device capable of improving the shock resistance against vibration and shock applied from the outside of the disk device both during non-operation and during operation. I do.

[0018]

SUMMARY OF THE INVENTION The present invention estimates the moving speed of a head for controlling the speed of actuator means for loading and unloading the head. Further, in order to cancel a disturbance load due to friction or the like that the head receives from a head retreat member such as a ramp block, the magnitude of the disturbance load is estimated. In estimating the head moving speed and the magnitude of the disturbance load, two factors are used. One is to detect a voltage generated in driving the actuator means and use a voltage signal as a result of the detection. The other is a drive signal in the drive means of the actuator means. Here, the drive signal in the drive unit may be a signal input to the drive unit or a signal output from the drive unit. Further, instead of the driving signal in the driving means, a control signal which is a source of generating the driving signal may be used. That is, a speed load estimating means for estimating the head moving speed and the magnitude of the disturbance load is provided, and the speed load estimating means converts a voltage signal detected by the voltage detecting means and a driving signal or a speed control signal in the driving means. As an input, a speed estimation signal and a load estimation signal are generated. The load estimation signal generated based on the two factors accurately estimates the magnitude of the disturbance load actually applied to the head. Since the head moving speed is estimated in parallel with the estimation of the disturbance load,
Accurate estimation is also made for the head moving speed. It is important to estimate the magnitude of the disturbance load directly in relation to the estimation of the head moving speed.

A drive signal is generated by synthesizing the load estimation signal with a control signal so as to cancel the disturbance load applied to the head using the load estimation signal accurately estimated as described above. By driving the actuator means of the head using the drive signal, a disturbance load applied to the head can be effectively canceled. Further, since the speed control is performed directly in association with the load estimation signal, the speed control can be performed sufficiently stably even when the frictional load on the head retreating member such as the ramp block is large at the time of loading / unloading. . That is, the reliability of the head load / unload operation can be improved.

Further, the load / unload operation shifts to a following operation through a seek operation.
At this time, it is preferable to control the position of the head with respect to the target track by performing the following switching. Using the servo information recorded in advance on the disk, this is detected by the head, and the position detecting means generates an error signal corresponding to the current position of the head. The position control means generates a position control signal corresponding to the error signal. Then, when proceeding to the following operation, the selecting means switches from the speed control signal at the time of the load / unload operation to the position control signal. The drive signal for the actuator means is obtained by combining the position control signal output from the selection means and the load estimation signal. As a result, the magnitude of disturbance loads such as bearing friction of the actuator means, elastic force of a flexible printed circuit connecting the actuator means and the electronic circuit board, and inertial force applied to the actuator means by external impact or vibration applied to the disk drive are reduced. It can be accurately estimated. The disturbance load involved in the estimation is a load estimation signal.

A drive signal is generated by synthesizing the load estimation signal with the position control signal output by the selection means so as to cancel the disturbance load applied to the actuator means using the load estimation signal accurately estimated as described above. . By driving the actuator means of the head using the drive signal, disturbance loads such as bearing friction, elastic force, and inertia force applied to the actuator means can be effectively canceled. That is, it is possible to compensate for an external force such as a bearing friction, an elastic force, or an inertial force acting on the actuator means. Even if it is large, the positioning control of the head to the target track can be performed sufficiently stably. That is, the positioning accuracy can be improved. In addition, as a side effect, it is possible to substantially increase the track density,
Realization of a large-capacity disk device can be promoted.

Further, at the time of recording / reproducing data to / from the disk, the level detecting means always monitors the magnitude of the load estimation signal generated by the speed load estimating means, and when the load estimation signal exceeds a predetermined value. Outputs the unload command as a selection signal and instantaneously retracts the head to the head retracting member such as the ramp block. Damage to the head and disk can be avoided without collision.

As described above, according to the present invention, it is possible to realize a highly reliable disk device having excellent shock resistance even when mounted on a portable computer or the like which is easily subjected to external vibrations and shocks. it can.

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be generally described.

According to a first aspect of the present invention, there is provided a disk drive comprising: an actuator for loading / unloading a head onto / from a disk; a drive for the actuator;
Voltage detection means for detecting a voltage generated in driving the actuator means and outputting a voltage signal; and a speed estimation signal for estimating a head moving speed and a magnitude of a disturbance load applied to the head from the drive signal and the voltage signal. Speed load estimating means for outputting a load estimating signal; speed controlling means for generating and outputting a speed control signal from a speed command signal and the speed estimating signal; and servo information prerecorded on the disk and detected by the head. Position detection means for generating and outputting an error signal corresponding to the current position of the head;
Position control means for generating and outputting a position control signal corresponding to the error signal, and selection means for receiving the speed control signal and the position control signal and selecting and outputting one of the control signals in response to a switching command And a level detecting means for outputting the switching signal to the selecting means in accordance with the load estimation signal, wherein the drive signal is obtained by synthesizing the control signal and the load estimation signal, and When the load estimation signal exceeds a predetermined value during recording and reproduction of the data, the head is unloaded. In this configuration, the drive signal in the drive unit may be input to the drive unit or output from the drive unit, and the same applies to the following.

The operation of the first invention is as follows. The speed load estimating means accurately estimates a head moving speed and a magnitude of a disturbance load applied to the head based on a driving signal of the driving means for driving the actuator means and a voltage signal detected in driving the actuator means. Can be. The head moving speed related to the estimation is a speed estimation signal, and the disturbance load related to the estimation is a load estimation signal. Here, it is particularly important that the magnitude of the disturbance load applied to the head can be accurately estimated from the drive signal and the voltage signal. It is also important that the head moving speed can be estimated in parallel with the estimation of the magnitude of the disturbance load. In the process of estimating the disturbance load, it is important that the head moving speed can be accurately estimated, and the magnitude of the disturbance load can be estimated in direct connection with the estimation of the head moving speed.

A drive signal is generated by synthesizing the load estimation signal with a control signal so as to cancel a disturbance load applied to the head using the load estimation signal accurately estimated as described above, and the head signal is used by using the drive signal. By driving the above actuator means, a disturbance load applied to the head can be effectively canceled. That is, it is possible to compensate for disturbance loads such as bearing friction of the actuator means acting on the actuator means and elastic force of the flexible printed circuit connecting the actuator means and the electronic circuit board. Even if the fluctuation of the frictional load at the head retreat member is large, the speed control can be performed sufficiently stably. That is, the reliability of the head load / unload operation can be improved.

Further, the operation of the first invention at the time of positioning the head with high precision on the target track is as follows. The switching operation after the head is loaded onto the disk from a head retreat member such as a ramp block shifts the operation to the positioning operation of the head to the target track. It is not always necessary for the head to perform loading / unloading operations from the head retracting member to the disk.
A seek operation from the save area on the disk may be performed. The selector switches to input of a position control signal from the position controller. The speed load estimating means is a flexible print for connecting the bearing means of the actuator means and the electronic circuit board based on a driving signal applied to the driving means for driving the actuator means and a voltage signal detected from the actuator means. It is possible to accurately estimate the magnitude of a disturbance load such as an elastic force of a circuit, and the inertial force applied to the actuator means due to an external impact or vibration applied to the disk device. The disturbance load involved in the estimation is a load estimation signal. Here, it is particularly important to be able to accurately estimate the magnitude of disturbance loads such as bearing friction, elastic force, and inertia force applied to the actuator means from the drive signal and the voltage signal during the following operation in which the head follows the target track. It is.

A drive signal is generated by synthesizing the load estimation signal with the position control signal output by the selection means so as to cancel the disturbance load applied to the actuator means using the load estimation signal accurately estimated as described above. If the actuator means of the head is driven by the drive signal, disturbance loads such as bearing friction, elastic force, and inertia force applied to the actuator means can be canceled well. That is, it is possible to compensate for an external force such as a bearing friction, an elastic force, or an inertial force acting on the actuator means. Even if it is large, the positioning control of the head to the target track can be performed sufficiently stably. That is, the positioning accuracy can be improved.

Further, the level detecting means constantly monitors the magnitude of the load estimation signal generated by the speed load estimating means,
When the load estimation signal exceeds a predetermined value due to a large vibration or impact applied to the disk device, a switching signal is output to the selection unit, and the selection unit is switched to the speed control unit. Since the speed control signal at this time functions to immediately unload the head, damage to the head and the disk can be avoided. That is, it is possible to realize a highly reliable disk device having excellent shock resistance against vibration and shock.

According to a second aspect of the present invention, in the disk device according to the first aspect, the speed load estimating means includes a comparing means to which a voltage signal detected by the voltage detecting means is input, A first multiplying means for multiplying a coefficient of 1 and a second multiplying means for multiplying an output of the comparing means by a second coefficient.
Multiplying means, first integrating means for integrating the output of the comparing means, and the sum of the output of the second multiplying means and the output of the first integrating means from the output of the first multiplying means And a second integrating means for integrating a value obtained by subtracting the above-mentioned value. The comparing means compares the voltage signal with the output of the second integrating means, and compares the result with the second multiplying means and the second multiplying means. It is configured to output to one integrating means.

The operation of the second invention is as follows. The output of the first multiplying means for inputting the drive signal becomes a drive torque estimation signal corresponding to the drive torque acting on the actuator means. The output of the second integrating means serves as a feedback element for the voltage signal input from the voltage detecting means. The output of the comparison means for calculating the difference between the voltage signal and the feedback element from the second integration means is provided to the first integration means and the second multiplication means. The output of the first integrating means for integrating the difference is a load estimation signal corresponding to a disturbance load such as friction received from the bearing by the actuator means, elastic force or inertia force received from the flexible printed circuit. The output of the second multiplying means obtained by multiplying the difference by a predetermined coefficient is added to the load estimation signal.
Then, a difference from the added value is obtained from the drive torque estimation signal, and is provided to the second integration means.

As a result of the above, the load estimation signal output from the first integrator means that the actuator means receives a disturbance load received from a bearing or a flexible printed circuit, or a disturbance such as an inertia force received by the actuator means due to an external impact or vibration. This corresponds to an accurate estimation of the load. Then, since the feedforward control is performed to cancel the disturbance load applied to the actuator means using the load estimation signal accurately estimated as described above, it is possible to compensate for the external force acting on the actuator means in the following operation, and to perform the following operation. Even if the disturbance load in the actuator means fluctuates sometimes, the positioning control of the head with respect to the target track can be performed sufficiently stably, and the positioning accuracy can be improved.

According to a third aspect of the present invention, there is provided a disk drive comprising: an actuator for loading and unloading a head onto and from a disk; a driving unit for the actuator;
Voltage detection means for detecting a voltage generated in driving the actuator means and outputting a voltage signal; speed control means for generating and outputting a speed control signal from a speed command signal and a speed estimation signal; and Position detection means for generating and outputting an error signal corresponding to the current position of the head from servo information detected by the head,
Position control means for generating and outputting a position control signal corresponding to the error signal, and selection means for receiving the speed control signal and the position control signal and selecting and outputting one of the control signals in response to a switching command Speed load estimating means for estimating a head moving speed and a magnitude of a disturbance load applied to the head from the voltage signal and the control signal output from the selecting means, and outputting the speed estimating signal and the load estimating signal; A level detection unit that outputs the switching signal to the selection unit in response to a load estimation signal, wherein the drive signal is obtained by synthesizing a control signal output from the selection unit and the load estimation signal; The head is unloaded when the load estimation signal exceeds a predetermined value at the time of recording / reproducing data on the head.

The operation of the third invention is as follows. The speed load estimating means can accurately estimate the head moving speed and the magnitude of the disturbance load applied to the head based on the control signal from the selecting means and the voltage signal detected in driving the actuator means. here,
In particular, it is important that the magnitude of the disturbance load applied to the head can be accurately estimated from the drive signal and the voltage signal. It is also important that the head moving speed can be estimated in parallel with the estimation of the magnitude of the disturbance load. In the process of accurately estimating the magnitude of the disturbance load, it is also possible to accurately estimate the head movement speed, and to estimate the magnitude of the disturbance load directly in relation to the estimation of the head movement speed. is important.

A drive signal is generated by synthesizing the load estimation signal with a control signal so as to cancel the disturbance load applied to the head using the load estimation signal accurately estimated as described above. If the actuator means of the head is driven using the drive signal, the disturbance load applied to the head can be effectively canceled. That is, it is possible to compensate for disturbance loads such as bearing friction acting on the actuator means and elastic force of a flexible printed circuit connecting the actuator means and the electronic circuit board. The speed control can be performed sufficiently stably even if the fluctuation of the friction load in the retreat member is large. That is, the head load
The reliability of the unload operation can be improved.

The operation according to the third aspect of the present invention at the time of positioning the head to the target track with high precision is as follows. The switching operation after the head is loaded onto the disk from a head retreat member such as a ramp block shifts the operation to the positioning operation of the head to the target track. It is not always necessary for the head to perform loading / unloading operations from the head retracting member to the disk.
A seek operation from the save area on the disk may be performed. The selector switches to input of a position control signal from the position controller. The speed load estimating means is a flexible print for connecting the bearing means of the actuator means and the electronic circuit board based on a driving signal applied to the driving means for driving the actuator means and a voltage signal detected from the actuator means. It is possible to accurately estimate an inertial force applied to the actuator means due to a disturbance load such as an elastic force of a circuit or an external shock or vibration applied to the disk device. The disturbance load involved in the estimation is a load estimation signal. Here, it is particularly important to be able to accurately estimate the magnitude of disturbance loads such as bearing friction, elastic force, and inertia force applied to the actuator means from the control signal and the voltage signal during the following operation in which the head follows the target track. It is.

A drive signal is generated by synthesizing the load estimation signal with the control signal output from the selection means so that the disturbance load applied to the actuator means is canceled with the load estimation signal accurately estimated as described above. If the actuator means of the head is driven by the drive signal, disturbance loads such as inertial force received by the actuator means due to bearing friction applied to the actuator means, elastic force of the flexible printed circuit, impact or vibration can be effectively canceled. That is, it is possible to compensate for an external force such as a bearing friction, an elastic force, or an inertial force acting on the actuator means. Even if it is large, the positioning control of the head to the target track can be performed sufficiently stably. That is, the positioning accuracy can be improved.

Further, the level detecting means constantly monitors the magnitude of the load estimation signal generated by the speed load estimating means, and when the vibration or shock applied to the disk device is large and the load estimation signal exceeds a predetermined value. A switching signal is output to the selection means to switch the selection means to the speed control means. Since the speed control signal at this time functions to immediately unload the head, damage to the head and the disk can be avoided. That is, it is possible to realize a highly reliable disk device having excellent shock resistance against vibration and shock.

According to a fourth aspect of the present invention, in the disk device according to the third aspect, the speed load estimating means includes a comparing means to which the voltage signal detected by the voltage detecting means is inputted, A first multiplying means for multiplying a coefficient of 1 and a second multiplying means for multiplying an output of the comparing means by a second coefficient.
Multiplying means, first integrating means for integrating the output of the comparing means, and second integrating means for integrating a value obtained by subtracting the output of the second multiplying means from the output of the first multiplying means. Wherein the comparing means compares the voltage signal with the output of the second integrating means, and outputs the result to the second multiplying means and the first integrating means. .

The operation according to the fourth aspect of the invention is as follows. The output of the first multiplying means, which receives the control signal from the selecting means, becomes a driving torque estimation signal corresponding to the driving torque acting on the actuator means. The output of the second integrating means serves as a feedback element for the voltage signal input from the voltage detecting means. The output of the comparison means for calculating the difference between the voltage signal and the feedback element from the second integration means is provided to the first integration means and the second multiplication means. The output of the first integrating means for integrating the difference is a load estimation signal corresponding to a disturbance load such as friction received from the bearing by the actuator means, elastic force or inertia force received from the flexible printed circuit. The difference from the output of the second multiplication means, which is obtained by multiplying the difference by a predetermined coefficient from the drive torque estimation signal, is provided to the second integration means. Second
Can be used as the speed estimation signal.

As a result, the load estimating signal output from the first integrating means accurately detects a disturbance load such as an elastic force received by the actuator means from a bearing or a flexible printed circuit or an inertial force received by the actuator means by impact or vibration. It is equivalent to that estimated. In addition, since the feedforward control is performed so as to cancel the disturbance load applied to the actuator means using the load estimation signal accurately determined as described above, it is possible to compensate for the external force acting on the actuator means in the following operation, and to perform the following operation. Even if the disturbance load in the actuator means fluctuates sometimes, the positioning control of the head with respect to the target track can be performed sufficiently stably, and the positioning accuracy can be improved. In addition, the second
It is not necessary to perform the addition of the first integrating means and the second multiplying means required in the invention of the third aspect, and the means for the addition can be omitted, and the configuration can be simplified.

According to a fifth aspect of the present invention, in the disk apparatus according to the first to fourth aspects, when the load estimation signal exceeds a predetermined value when recording data on the disk, the recording by the head is performed. Prohibiting and unloading the head.

The operation of the fifth invention is as follows. In the first to fourth inventions, the speed load estimating means is configured to output an inertial force received by the actuator means due to an external impact or vibration applied to the disk device as the load estimation signal. Therefore, the level detection means always monitors the magnitude of the load estimation signal, and if the load estimation signal exceeds a predetermined value, the head is prohibited from recording on the disk. When forcibly unloading, it is possible to avoid erroneous erasure of data on the disk by the head.

The disk device of the sixth aspect of the present invention is the disk device according to the first to fifth aspects, wherein the speed load estimating means is:
It is configured to output the load estimation signal in a state where high frequency components are cut off.

The operation according to the sixth aspect of the invention is as follows. In the first to fifth aspects of the present invention, a load estimation signal for a disturbance load due to actual friction or the like is generated by estimation using a secondary delay system. It has a low-frequency cutoff filter characteristic that provides an excellent disturbance load suppressing effect at a frequency (estimated angular frequency) or less. Therefore, if the speed load estimating means is configured to generate the load estimation signal in a state where the natural angular frequency and the damping factor are appropriately set and high frequency components are cut off, an extremely excellent disturbance load suppression effect is exhibited. Can be done.

In the disk device according to a seventh aspect of the present invention, in the first to sixth aspects, the control band of the speed load estimating means is set to be larger than the control band of the position control means or the speed control means. Have been.

The operation of the seventh aspect is as follows. To extend the control band of the positioning control system is to increase the proportional gain, but there is an upper limit depending on the sampling frequency of the sector servo of the disk drive and the natural mechanical resonance frequency of the actuator means. On the other hand, the speed load estimating means is not affected by the sampling frequency of the sector servo of the disk device. Therefore, in the speed load estimating means, the control band can be set higher than the control band of the positioning control system or the speed control system. As a result, the head can accurately follow the target track over a higher control band. Further, since the vibration and the shock applied to the disk device can be detected with high sensitivity, the reliability against the vibration and the shock can be further improved.

The present invention operates most advantageously when applied to a magnetic disk drive, but is not necessarily limited to a magnetic disk drive.

(Specific Embodiment) Hereinafter, a specific embodiment of a disk drive according to the present invention will be described in detail with reference to the drawings. Note that components having similar functions are described with the same reference numerals.

Embodiment 1 FIG. 1 is a block diagram showing a configuration of a magnetic disk drive according to Embodiment 1 of the present invention.

In FIG. 1, reference numeral 1 denotes a magnetic disk which is rotated by a spindle motor (not shown).
Reference numeral 2 denotes a magnetic head for recording and reproducing data on and from the magnetic disk 1. Reference numeral 3 denotes an arm, and a magnetic head 2 mounted at one end.
Is rotated around the bearing 4 so that the magnetic head 2
Is moved to a target track on the magnetic disk 1.
Reference numeral 5 denotes a driving coil provided at the rear end of the arm 3, and reference numeral 6 denotes a stator. A magnet (not shown) is disposed on a surface facing the driving coil 5. The arm 3 receives a rotational force due to the interaction between the magnetic flux generated by the magnet disposed on the stator 6 and the magnetic field generated by the current supplied to the drive coil 5. Reference numeral 7 denotes a ramp block serving as a head retracting member disposed outside the area occupied by the magnetic disk 1, and 8 denotes an arm 3.
A tab holding surface is formed on the ramp in the ramp block 7 and slides with the suspension tab 8 according to the rotation of the arm 3. An actuator 9 is constituted by the magnetic head 2, the arm 3, the bearing 4, the drive coil 5, the stator 6, the ramp block 7, and the suspension tab 8.

Reference numeral 10 denotes a driver, and reference numeral 11 denotes a voltage detector included in the driver 10, which detects a voltage generated at both ends of the drive coil 5 and outputs a voltage signal Va. Reference numeral 12 denotes a speed load estimator which estimates the moving speed of the arm 3 and the load torque acting on the arm 3 from the voltage signal Va output from the voltage detector 11 and the drive signal u input to the driver 10. An estimated signal v _est and a load estimated signal τd _est are output. 13 is a comparator, outputs an error signal ev between the speed command signal vr and velocity estimation signal v _est. A speed controller 14 performs amplification and phase compensation based on the error signal ev obtained by the comparator 13, and then generates a speed control signal cv. The speed control signal cv is input to the input terminal a of the switch 18.
In each sector of the magnetic disk 1, a track position signal is recorded in advance as servo information, and this position signal is read by the magnetic head 2. The position detector 16 detects the current position of the magnetic head 2 based on the position signal read by the magnetic head 2, and generates a position error signal ex indicating a difference from the target position r of the target track. Position controller 1
7 receives the position error signal ex generated by the position detector 16 and performs amplification and phase compensation to generate a position control signal cx. The position control signal cx is input to the input terminal b of the switch 18. Load estimation signal generated by the speed load estimator 12 .tau.d _est is inputted to the correction circuit 15 and the level detector 19. The compensator 15 includes a switch 18
Is an output control signal c (either the position control signal cx a speed control signal cv) and load estimated signal .tau.d _{e st} speed load estimator 12 is input, after performing correction calculation by the correction circuit 15, the driving The signal u is output to the driver 10. Driver 10
Supplies a drive current Ia to the drive coil 5 in accordance with the input drive signal u, rotates the drive coil 5 around the bearing 4,
The magnetic head 2 attached to the tip of the disk is rotated. The switch 18 is connected to the load terminal input to the command terminal 20.
Selects one of the speed control signal cv generated by the speed controller 14 and the position control signal cx generated by the position controller 17 in response to the switching command between the unload command and the following command, and controls the compensator 15. The signal c is output. Level detector 19 outputs a switching signal t to the selector 18 when monitoring the input load estimated signal .tau.d _est exceeds a predetermined value.

As a result, when a load / unload command is input to the command terminal 20 of the switch 18 as a switching command,
The switch 60 of the switch 18 is connected to the terminal a to move the magnetic head 2 to a target track on the magnetic disk 1 at a smooth speed. The arm 3 is connected to the magnetic disk 1
The magnetic head 2 can be smoothly retracted from the magnetic disk 1 to the ramp block 7 by placing the suspension tab 8 of the head arm 3 on the tab holding surface of the ramp block 7 when the magnetic head 2 is rotated to the outer peripheral side. . When a following command is input to the command terminal 20 of the switch 18 as a switch command, the switch 6 of the switch 18
Numeral 0 is connected to the terminal b so that the magnetic head 2 is positioned with high accuracy on a target track formed with a narrow track pitch in order to record and reproduce data on the magnetic disk 1.

The magnetic disk drive of the first embodiment can switch between completely different control between the moving speed control of the magnetic head and the positioning control to the target track in accordance with the switching command to the switch 18. Then, level detector 19, so outputs a switching signal t to the selector 18 when the load estimating signal .tau.d _est exceeds a monitoring predetermined value, the magnetic disk device, from the positioning control to the target track of the magnetic head The control can be switched to the moving speed control, and when the vibration or impact is large, the magnetic head is immediately unloaded, so that damage to the head and the disk can be avoided.

Here, in contrast to the description in the claims, the driver 10 corresponds to the driving means and the voltage detector 1
1 corresponds to the voltage detecting means, the speed load estimator 12 corresponds to the speed load estimating means, the speed controller 14 corresponds to the speed controlling means, the position detector 16 corresponds to the position detecting means, Reference numeral 17 corresponds to position control means, switch 18 corresponds to selection means, and level detector 19 corresponds to level detection means.

Next, the operation of the speed control system of the magnetic disk drive according to the first embodiment will be described with reference to FIG. FIG.
FIG. 3 is a block diagram showing an overall configuration of a speed control system when the switch 60 of the switch 18 is connected to the terminal a in the magnetic disk device of the first embodiment. In FIG. 2, s represents the Laplace operator.

In FIG. 2, if the moving speed of the magnetic head 2 is denoted by v, and the moving speed v is denoted by _vest , the speed estimation signal obtained by the speed load estimator 12 indicated by the block 30 is represented by vest, the speed command signal vr The error signal ev is

[0059]

(Equation 1) The error signal ev is obtained by the comparator 13. The speed controller 14 represented by the block 21 filters the error signal ev with the transfer function Gv (s),
A speed control signal cv is generated and output to the switch 18. The speed control signal cv becomes the drive signal u via the adder 46. The drive signal u is converted from the voltage signal into a gm-times current signal in the driver 10 of the block 22 (the transfer function is gm), and the drive signal Ia is output. In the actuator 9 represented by the block 23, the drive current Ia supplied to the drive coil 5 has a transfer function Ka due to the interaction between the magnetic field generated by the drive coil 5 and the magnetic flux of the magnet of the stator 6 described above.
At t, it is converted to drive torque τ. Here, the transfer function Kt is a torque constant of the actuator 9. The transfer function (Lb / J · s) of the block 24 represents a transfer characteristic from the drive torque τ acting on the arm 3 to the moving speed v of the magnetic head 2. Here, J indicates the moment of inertia of the arm 3, and Lb indicates the distance from the bearing 4 of the arm 3 to the magnetic head 2. In the voltage detector 11 represented by the blocks 26 and 27, the block 26 outputs an induced voltage Ea generated at both ends of the drive coil 5 when the actuator 9 rotates, and the block 27 supplies a drive current to the drive coil 5. The voltage drop (Ra + La · s) · Ia generated by the conduction of Ia is output, and the adder 28 adds them to output the terminal voltage of the actuator 9 as a voltage signal Va. That is,

[0060]

(Equation 2) There is a relationship. Here, Ra indicates the coil resistance of the drive coil 5, and La indicates the inductance of the drive coil 5.

The disturbance load τd acting on the arm 3, such as the sliding friction between the tab holding surface on the ramp block 7 and the suspension tab 8, can be expressed by the comparator 25 as input to the stage preceding the block 24.

Block 3 in a portion surrounded by a dashed line in FIG.
0 is a block diagram of the speed load estimator 12, and this block 30 is a block 2 of the driver 10.
2, a block 33 having the same transfer function as the transfer function of the block 23 that is the actuator 9, a block 34 having the same transfer function as the transfer function of the block 24, Table 11
And a block 39 having the same transfer function as the transfer function of the block 26 and a block 39 having the same transfer function as the transfer function of the block 27. Block 41 combining block 32 and block 33 is a first multiplier, block 44 is a second multiplier, block 43 is a first integrator, and block 4 is a combination of block 34 and block 35.
Reference numeral 2 denotes a second integrator. Here, the suffix “n” of each constant in the block 30 indicates a nominal value, and the variable with “est” indicates an estimated value. here,
In contrast to the claims, the first multiplier corresponds to the first multiplying means, the second multiplier corresponds to the second multiplying means, and the first integrator corresponds to the second integrator. 1 integrator, the second integrator corresponds to the second integrator, and the comparator 3
7 corresponds to the comparison means.

The drive signal u input to the block 22 is
The driving torque τ acting on the head arm 3 is also input to the block 32 constituting the speed load estimator 12 and multiplied by (gmn · Ktn) between the block 32 and the block 33.
And the same drive torque estimation signal τ _est is obtained.

In FIG. 2, the speed estimation signal _vest output from the block 34 is fed back to the comparator 13 as the moving speed v of the magnetic head 2. Block 35
In the voltage drop of the induced voltage estimation signal Ea _est obtained by multiplying Kvn velocity estimation signal v _est, the estimated current Ia _est to the actuator 9 generated by being energized (Ran + Lan · s) · Ia est bets are added by the adder 36, the adder 36, the voltage estimation signal Va _est is outputted. The voltage estimation signal Va _est is input to the comparator 37 and compared with the actually detected voltage signal Va, and the resulting error signal α (= Va−V a _est ) is represented by the first integration represented by the block 43. And a second multiplier, represented by block 44. The first integrator 43 integrates the error signal alpha, and outputs the load estimated signal .tau.d _est for disturbance load. The error signal α is input to the second multiplier represented by the block 44, multiplied by g 1 and added to the adder 38.
The output of the adder 38 is input to the subtractor 31 and the block 3
3 from the drive torque estimation signal τ _est output from
Is output to the block 34.

The coefficient g1 of the block 44 and the coefficient g2 of the block 43 are constants for stabilizing the operation of the speed load estimator 12, and the details will be described later.

In FIG. 2, a block 47 surrounded by a dashed line is a block diagram of the corrector 15. The block 45 included in the corrector 15 includes a load estimation signal τ
By multiplying 1 / (gmn · Ktn) to d _est, and generates a correction signal β to the driver 10 required to generate the driving force of the magnitude corresponding to the load estimating signal .tau.d _est to the head arm 3 . The correction signal β is added to the speed control signal cv in the adder 47.

Next, the speed load estimator 12 in block 30
Will be described in detail with reference to FIG.

[0068] FIGS. 3 (a) is a block diagram rewritten block 30 of FIG. 2 shows the transfer from the input of the drive signal u to the output of the load estimator signal .tau.d _est. FIG. 3B is a block diagram of FIG. 3A in which the input position (comparator 37) of the voltage signal Va is equivalently converted and moved based on (Equation 2). It is a block diagram which transformed the block diagram of a). Here, for the sake of simplicity, the value of gm in block 22 in FIG.

[0069]

(Equation 3) , The drive current Ia (= gmu) and the estimated current Ia _est
(= Gmn · u).

Focusing on the first and second terms of (Equation 2), Ea of the first term can be obtained by multiplying the magnitude by (Jn · s) / (Lbn · Kvn) as shown in FIG. The input position of the comparator 37 of FIG.
It can be equivalently moved to the input position of the subtractor 48 shown in FIG. Also, (Ra + La ·) in the second term of (Equation 2)
s) · Ia can be included as a block 39 in FIG. 3A and expressed as a block 49 in FIG. 3B.

Focusing on the subtractor 48 in FIG. 3B, δ, which is the output of the subtractor 48, is expressed as (Equation 4).

[0072]

(Equation 4) Next, focusing on the comparator 25 and the blocks 24 and 26 in FIG.

[0073]

(Equation 5) Here, for simplicity,

[0074]

(Equation 6)

[0075]

(Equation 7) Assuming that (Equation 5) is substituted into (Equation 4), (Equation 4)
Is transformed as shown in (Equation 8).

[0076]

(Equation 8) That is, the output δ of the subtractor 48 is equal to the disturbance load τd applied to the arm 3. Therefore, from the block diagram in FIG. 3 (b), when obtaining the transfer function from the disturbance load .tau.d due to friction or the like applied to the arm 3 to the load estimating signal .tau.d _est, as shown in equation (9).

[0077]

(Equation 9) From (Equation 9), the speed load estimator 12 uses the loop in the block 30 surrounded by the dashed line in FIG.
From the voltage signal Va and the disturbance load τd due to actual friction, etc.
Can be estimated by a second-order delay system.

Here, if the natural angular frequency (estimated angular frequency) of the second-order delay system is ωo and the damping factor is ζo,
The constants g1 and g2 for stabilizing the operation of the speed load estimator 12 are expressed by the following (Equation 10) and (Equation 11), respectively.

[0079]

(Equation 10)

[0080]

[Equation 11] Here, if the estimated angular frequency ωo is set sufficiently higher than the speed control band fc and the damping factor ζo is selected from 0.7 to 1, the speed load estimator 12 causes the disturbance load τ
d can be accurately estimated.

By transforming (Equation 9) using (Equation 10) and (Equation 11),

[0082]

(Equation 12) Becomes That is, the block diagram of the speed load estimator 12 in FIG. 3A can be simplified as shown by a block 52 in FIG. 3C.

Next, the operation of the corrector 15 indicated by the block 47 will be described in detail with reference to FIG.

Block 4 in a portion surrounded by a chain line in FIG.
7 shows a block diagram of the corrector 15. Block 45
Outputs the load estimated signal _{τd est 1 / (gmn · Ktn} ) multiplied by the correction signal β to the adder 46. That is, the load estimating signal by multiplying 1 / (gmn · Ktn) the .tau.d _est, the adder 46 a correction signal β required to generate a driving force of the magnitude corresponding to the load estimating signal .tau.d _est to the actuator 9
Output to In addition, since the correction signal β is multiplied by gmn · Ktn by the block 22 and the block 23, the load estimation signal τ is previously set in order to match the magnitude.
d _est is multiplied by 1 / (gmn · Ktn).

[0085] In summary, the magnetic disk apparatus of the first embodiment, so as to cancel the disturbance load .tau.d due to friction or the like, it is possible that the load estimation signal .tau.d _est is configured to act on the actuator 9 .

FIG. 4A is a block diagram of the block diagram of FIG. 2, in which the portions from the adder 46 to the comparator 25 and the block 24 related to the operation of the corrector 15 are extracted. FIG. 4B shows that the disturbance load τd applied to the comparator 25 and the disturbance load τd applied to the block 52 are represented by one τ.
It is the block diagram put together in d. Components having the same functions as those in the block diagram of FIG. 2 are denoted by the same reference numerals, and redundant description will be omitted.

In the block diagram of FIG. 4A, the block 52 corresponds to the block 52 of FIG.
It has a transfer function represented by 2).

Therefore, from FIG. 4B, the disturbance load τd due to friction or the like applied to the arm 3 from the outside is given by (Equation 13)
Can be considered to be added to the speed control system through a filter expressed by the following transfer function.

[0089]

(Equation 13) FIG. 5 shows the frequency characteristic of the transfer function Gd (s) represented by (Equation 13) by a polygonal line approximation. From the frequency characteristics of the transfer function Gd (s) shown in FIG. 5, at an angular frequency lower than the angular frequency ωo, the gain is 0 dB or less, and −20 dB / dec (decade) as the angular frequency ω falls.
At the attenuation ratio of dec means 10 times.
That is, as shown in FIG. 5, the transfer function Gd (s) has a low-frequency cutoff filter characteristic capable of suppressing frequencies lower than the angular frequency ωo.

That is, in the magnetic disk drive according to the first embodiment of the present invention, even if a disturbance load τd due to friction or the like acts on the arm 3, the disturbance load τd is estimated by the speed load estimator 12, and the load estimation signal is obtained. It is configured to control so as to cancel the externally applied disturbance load τd by τd _est . Therefore, the externally applied disturbance load τ
d acts as if it were added to the speed control system through the filter having the cutoff frequency characteristic of (Equation 13) and FIG. Therefore, in the magnetic disk drive according to the first embodiment of the present invention, at a frequency equal to or lower than the angular frequency ωo,
Disturbance load due to friction or the like can be suppressed by the first-order low-frequency cutoff characteristics.

FIG. 6 is a time response waveform diagram for describing in more detail the disturbance load suppressing effect of the speed load estimator 12 of the magnetic disk drive according to the first embodiment of the present invention. 6 (a) is, when the step-like disturbance load .tau.d as shown in 54 of FIG joined to the arm 3, showing the load estimation signal .tau.d _est waveform 55 the speed load estimator 12 outputs.

Here, the estimated frequency fo (ωo = 2πf) for determining the control parameters of (Equation 10) and (Equation 11)
o) and the value of the damping factor ζo are each 3 kHz
The simulation was performed by setting the control band of the speed control system to 300 Hz. 6 (b) shows the simulation result of the head moving speed v when you do not enter a load estimated signal .tau.d _est outputted by the speed load estimator 12 in the corrector 15.

A dotted line 56 in FIG. 6B shows the speed command signal vr, and a solid line 57 shows a time waveform of the head moving speed v. The head moving speed v greatly fluctuates when a step-like disturbance load fluctuation occurs.

[0094] FIG. 6 (c), the load estimator signal .tau.d _est outputted by the speed load estimator 12 is input to the corrector 15 by the action of the load estimation signal .tau.d _est so as to cancel the fluctuation of the disturbance load to the actuator 9 4 shows a simulation result of the head moving speed v in the case of the above. 6C shows a speed command signal vr, and a solid line 59 shows a time waveform of the head moving speed v. Even if a step-like disturbance load fluctuation is applied, the head moving speed v hardly fluctuates, and the disturbance load suppression effect is greatly improved as compared with the case of FIG.

As a result, in the magnetic disk drive of the first embodiment of the present invention, the speed load estimator can accurately detect the moving load of the head and the disturbance load due to friction and the like, and the friction load on the ramp block can be detected. Even if the fluctuation is large, stable speed control is possible, and the reliability of the head load / unload operation can be improved.

In the magnetic disk drive according to the first embodiment of the present invention, the drive signal u output from the block 47 is input as one input signal to the speed load estimator 12. It goes without saying that the same effect can be obtained by using the drive current Ia output from the driver output from the block 22 instead of the signal u.

Next, the operation of the positioning control system when the switch 60 is connected to the terminal b in the magnetic disk drive of the first embodiment will be described with reference to FIG. FIG. 7 is a block diagram showing the overall configuration of the positioning control system. A portion 30 surrounded by a dashed line in the drawing is a block of the speed load estimator 12, and is the same block diagram as the block 30 in FIG. Similarly, a portion 47 surrounded by an alternate long and short dash line is a block of the compensator 15. In FIG. 7, s
Represents the Laplace operator. Since servo information recorded on a magnetic disk is recorded on the disk in a discrete state having a fixed sampling period, a magnetic disk device generally employs a sector servo method for head positioning control. In FIG. 7, the hold element by sampling the sector servo is omitted for simplicity of description.

In FIG. 7, if the current track position detected by the magnetic head 2 is x, the position error ex with respect to the target track position r is expressed by (Equation 14). can get.

[0099]

[Equation 14] The position controller 17 represented by the block 61 in FIG. 7 adds the transfer function Gx to the position error signal ex output from the comparator 71.
The digital filter processing of (z) is performed to generate a position control signal cx, which is output to the corrector 15 represented by a block 47. The positioning control system is subjected to ordinary PID control, and the transfer function of the position controller 17 can be expressed by (Equation 15).

[0100]

(Equation 15) Here, z ⁻¹ indicates one sample delay, and Kx indicates a proportional gain of the positioning control system. Coefficients _ad and _ai indicate constants representing frequency characteristics, coefficient _ad is a differential coefficient, and coefficient _ai is an integral coefficient. To extend the control band of the positioning control system is to increase the proportional gain Kx, but this has an upper limit due to the sampling frequency of the sector servo of the magnetic disk drive and the natural mechanical resonance frequency of the actuator mechanism. On the other hand, the speed load estimator 12 configured in the same manner as the block 30 in FIG. 2 is not affected by the sampling frequency of the sector servo of the magnetic disk drive. Therefore, the control band of the speed load estimator 12 can be set higher than the control band of the positioning control system. The position control signal cx becomes a drive signal u via the adder 46. The drive signal u is supplied to the block 22
In the driver 10 (the transfer function is gm), the voltage signal is converted into a gm-fold current signal, and the driving current Ia is output. In the actuator 9 represented by the block 23, the drive current Ia applied to the drive coil 5 is converted into the drive torque τ by the transfer function Kt by the interaction between the magnetic field generated by the drive coil 5 and the magnetic flux of the magnet of the stator 6 described above. Is done. Here, the transfer function Kt is a torque constant of the actuator 9. Transfer function of block 24 (Lb / Js)
Is calculated from the drive torque τ acting on the arm 3
Represents the transfer characteristic of the moving speed to the moving speed v. Here, J indicates the moment of inertia of the arm 3, and Lb indicates the bearing 4 of the arm 3.
2 shows the distance from the magnetic head 2 to the magnetic head 2. Block 6
Reference numeral 2 denotes an integrator whose transfer function is represented by 1 / s, and converts the moving speed v of the magnetic head 2 into a current track position x. In the voltage detector 11 represented by the blocks 26 and 27, the block 26 outputs an induced voltage Ea generated at both ends of the drive coil 5 when the actuator 9 rotates, and the block 27 supplies a drive current to the drive coil 5. The voltage drop (Ra + La ·
s) · Ia is output, and the terminal voltage of the actuator 9 is added to the voltage signal Va
Output as

Acting on the arm 3 such as the bearing friction of the actuator 9, the elastic force of the flexible printed circuit connecting the actuator 9 and the electronic circuit board, and the inertial force received by the actuator 9 due to shock or vibration applied to the magnetic disk device from outside. The disturbance τd can be expressed in a form that is input to the comparator 25 before the block 24. The block 30 surrounded by the one-dot chain line in FIG.
Shows a block diagram, and outputs the load estimated signal .tau.d _est in block 47 constituting the corrector 15.

The position control signal cx output from the block 61 becomes the drive signal u via the adder 46 constituting the corrector 15 and is input to the driver 10 represented by the block 22. Block 47 corrector 15, the input position control signals cx, adder 46 a correction signal β load estimation signal .tau.d _est generated by the speed load estimator 12 1 / (gmn · Ktn) times to And outputs a drive signal u. That is, the load estimating signal .tau.d _{e st} to 1 / (gmn · Ktn) the actuator 9 by multiplying the load estimating signal .tau.d _{e st} required to generate a driving force of the magnitude corresponding to the correction signal β adder 46 Output to Therefore, the magnetic disk drive of the first embodiment uses the actuator with the load estimation signal τd _est to cancel the disturbance load τd such as the bearing friction of the bearing 4 and the elastic force of the flexible printed circuit connecting the actuator 9 and the electronic circuit board. 9.

That is, in the magnetic disk drive according to the first embodiment of the present invention, even when a disturbance τd due to bearing friction, elastic force, inertia force or the like acts on the arm 3, the disturbance τd is estimated by the speed load estimator 12. and it is configured to control so as to cancel the disturbance .tau.d of externally applied with the load estimating signal .tau.d _est. Therefore, the externally applied disturbance .tau.d acts as if it were added to the head positioning control system through the filter having the cut-off frequency characteristic of (Equation 13) and FIG. Therefore, in the magnetic disk drive according to the first embodiment of the present invention, at frequencies lower than the angular frequency ωo, the actuator 9 has the primary low-frequency cutoff characteristic.
Disturbance due to the bearing friction of the actuator 9, the elastic force of the flexible printed circuit connecting the actuator 9 and the electronic circuit board, and the inertial force received by the actuator 9 due to the shock or vibration applied to the magnetic disk drive from the outside.

In the magnetic disk drive according to the first embodiment of the present invention, the speed load estimator 12 can accurately detect a disturbance due to an inertia force applied to the actuator 9 due to externally applied vibration or impact. Estimated signal τ
By inputting d _est to the corrector 15, a track shift due to disturbance can be suppressed. As a result, the positioning of the magnetic head 2 on the target track is controlled with high precision. Therefore, the magnetic disk device according to the first embodiment of the present invention can perform stable tracking control against vibration and impact, and can improve the reliability of the disk device.

FIG. 8 is a time response waveform diagram for explaining in more detail the disturbance suppressing effect of the speed load estimator 12 of the magnetic disk drive according to the first embodiment of the present invention.

FIG. 8A shows the case where the maximum angular acceleration (d
ωo / dt) is 1000 Rad / s ² (radian / second ² )
Is applied to the magnetic disk drive, a waveform 63 (indicated by a broken line) of a disturbance τd of the inertial force applied to the actuator 9 and a load estimation signal τd _est output from the speed load estimator 12. A waveform 64 is shown. The moment of inertia J around the bearing 4 of the actuator 9 is 1 g · cm.
Assuming ² , the maximum value of the disturbance τd is

[0107]

(Equation 16) Becomes

Here, the estimated frequency fo (ωo = 2πf) for determining the control parameters of (Equation 10) and (Equation 11)
o) and the value of the damping factor ζo are each 3 kHz
The simulation was performed by setting the control band of the position control system to 400 Hz.

The speed load estimator 12 receives the input of the driver 10
And the voltage signal output from the voltage detector 11
The disturbance torque τd acting on the actuator 9 is estimated from Va.
And there is a slight time delay, but the actual disturbance τd
Load estimation signal τd almost similar to _estIs output.

[0110] FIG. 8 (b), the disturbance τ enter the load estimation signal .tau.d _est outputted by the speed load estimator 12 in the corrector 15
a waveform 66 of the drive current Ia when the load estimating signal .tau.d _est allowed to act on the actuator 9 so as to cancel the variation due to d, of the waveform 65 of the drive current Ia when no load estimation signal .tau.d _est input to the corrector 15 The simulation result is shown. Note that the torque constant Kt of the actuator 9 is
23 dyn · cm / mA. Since the servo information recorded on the magnetic disk is recorded on the disk in a discrete state having a fixed sampling period, the head position signal is not a continuous signal. Therefore, the position control signal cx of the position controller 17 where the digital processing is performed changes stepwise. As a result, the waveform of the drive current Ia of the actuator 9 when no load estimation signal .tau.d _est input to the corrector 15, the same as the waveform of the position control signal cx, FIG 6 (b)
(Ia = gm ·)
c = gm · u). Waveform 6 of the drive current Ia of the actuator 9 when a load estimating signal .tau.d _est inputted to the correction circuit 15
6, because it is generated by adding the corrector 15 the load estimation signal .tau.d _est speed load estimator 12 on the position control signal cx of the position controller 17, when the rotary impact is applied to the magnetic disk device (t = The time delay from 0) is shown in FIG.
Is smaller than the waveform 65 of FIG.

[0111] FIG. 6 (c), and the load estimating signal .tau.d _est to the load estimation signal .tau.d _est outputted by the speed load estimator 12 is input to the corrector 15 cancel the variation of the load to act on the actuator 9 Waveform 68 of position error signal e in case
7 shows a simulation result of the waveform 67 of the position error signal e when the speed load estimator 12 is not applied. Even if a half-sinusoidal rotational shock is applied to the magnetic disk drive from the outside, if the speed load estimator 12 is applied, the track error signal e does not fluctuate greatly like the waveform 68 and the speed load estimator 12 is not applied. The disturbance suppressing effect is improved as compared with the waveform 67 in the case.

The magnetic disk device is often mounted on a portable computer or the like, and such a portable disk device is susceptible to external vibrations and shocks. Also for such vibration or shock magnetic disk apparatus of the first embodiment of the present invention, the disturbance .tau.d applied from These externally estimated by velocity load estimator 12, with in loading estimation signals .tau.d _est,
Control is performed to cancel the disturbance τd.

During operation of the magnetic disk device, that is, in a state where a magnetic head is on the disk and data is recorded / reproduced, and a normal vibration and a large shock are not applied, the switch 60 of the switch 18 is turned on. It is connected to the terminal b. Therefore, data is recorded and reproduced on the target track by the magnetic head 2. The level detector 19, the speed load estimator 12 is generated by the load estimated signal .tau.d _est absolute value level detector when higher than the threshold level 1
9 outputs an "H" level switching signal t. Here, the threshold level is a value corresponding to a vibration or an impact that causes the magnetic head 2 to largely deviate from the target track.
The switching signal t output from the level detector 19 is
Has been entered. When the switching signal t is at the "H" level, the switch 60 of the switch 18 is switched from the terminal b to the terminal a, so that the magnetic disk device switches from the positioning control to the target track to the moving speed control of the magnetic head. be able to. Therefore, when the vibration or impact is large, the magnetic head is immediately unloaded.

With this structure, when a large vibration or impact is likely to damage the head and the disk, the magnetic head 2 can be immediately retracted to the ramp block 7, so that the head and the disk are damaged. Can be avoided. Data that could not be recorded and reproduced may then be recorded and reproduced again.

As a result, in the magnetic disk drive according to the first embodiment of the present invention, when a load / unload command is input to the command terminal 20 of the switch 18 in FIG. Is connected to the terminal a and moves the magnetic head 2 to a target track on the magnetic disk 1 at a smooth speed. Further, the magnetic head 2 can be smoothly retracted from the magnetic disk 1 to the ramp block 7. When a following command is input to the command terminal 20 of the switch 18 as a switching command, the switch 60 of the switch 18 is connected to the terminal b, and the magnetic head 2 is positioned and controlled with high accuracy on the target track. . Magnetic head 2
When a large vibration or a shock is applied while data is recorded on or reproduced from the disk 1 and the data is reproduced, the level detector 19 outputs the "H" level switch signal t to the switch 18.
Therefore, the switch 60 of the switch 18 is switched from the terminal b to the terminal a, and the magnetic head 2 is immediately unloaded.

Therefore, according to the magnetic disk drive of the first embodiment of the present invention, the moving speed of the head can be accurately detected by the speed load estimator 12, and the fluctuation of the friction load on the ramp block 7 is large. However, stable speed control is possible, and the reliability of the load / unload operation of the magnetic head 2 can be improved. The magnetic head 2
In the following operation, the bearing 4 is attached to the actuator 9.
Even if the bearing friction and the elastic force of the flexible printed circuit, etc. act on the speed load estimator 1
2 and the compensator 15, the positioning accuracy of the magnetic head 2 can be improved. Further, the vibration and shock applied to the magnetic disk drive can be detected with high sensitivity by the speed load estimator 12, and the magnetic head 2 can be unloaded when a large vibration or shock is applied. The impact resistance of the magnetic disk device can be improved without damaging the head and the disk.

(Embodiment 2) FIG. 9 is a block diagram showing a configuration of a magnetic disk drive according to Embodiment 2 of the present invention. FIG. 10 is a block diagram showing the overall configuration of the speed control system when the switch 60 of the switch 18 is connected to the terminal a in the magnetic disk drive of the second embodiment. Note that components having the same functions as those of the first embodiment are denoted by the same reference numerals, and redundant description will be omitted.

In the magnetic disk drive according to the second embodiment shown in FIG. 9, the difference from the first embodiment shown in FIG. 1 is a signal input to the speed load estimator. That is, FIG.
In the first embodiment, the voltage signal Va generated by the voltage detector 11 and the drive signal u are input to the speed load estimator 12, but in the second embodiment shown in FIG. The voltage signal Va generated by the switch 11 and the control signal c output from the switch 18 are input to the speed load estimator 70.

[0119] load estimated signal .tau.d _est generated by the speed load estimator 70 of Figure 9 is inputted to the correction circuit 15 and the level detector 19. The compensator 15 includes a control signal c output from the switch 18 and a load estimation signal τd of the speed load estimator 70.
_est is input, and after performing a correction operation in the corrector 15,
The drive signal u is output to the driver 10.

FIG. 10 is a block diagram of the speed load estimator 70 in the block 40 surrounded by the dashed line. The speed load estimator 70 receives as input the voltage signal Va generated by the voltage detector 11 which is the output of the adder 28 and the speed control signal cv generated by the speed controller 17 represented by the block 21. In the speed load estimator 12 according to the first embodiment, the following is performed. First integrator block 43
The signal obtained by multiplying the signal obtained by multiplying the coefficient (g2 / s) by the coefficient (g1) of the block 44 of the second multiplier is added by the adder 38. The signal obtained as a result of the addition and the coefficient (gmn ·
Ktn) a drive torque estimation signal tau _est obtained by multiplying is input to the subtracter 31. The signal γ obtained by the subtractor 31 was input to the block 42 of the second integrator. That is, since the drive signal u to which the correction signal β is added is input to the speed load estimator 12, the adder 38 in FIG. 2 is required. However, since the speed load estimator 70 according to the second embodiment has a configuration in which the speed control signal cv before the addition of the correction signal β is input, the adder 38 as shown in FIG. 2 is unnecessary.

In FIG. 10, a block 41 that combines the blocks 32 and 33 constitutes a first multiplier, a block 44 constitutes a second multiplier, a block 43 constitutes a first integrator, and a block 34 constitutes a first multiplier. A block 42 including the block 35 constitutes a second integrator.

The operation of the speed load estimator 70 in the magnetic disk device of the second embodiment configured as described above is compared with the operation of the speed load estimator 12 of the first embodiment described above with reference to FIGS. This will be described with reference to FIG.

First, in FIG. 2, the input of the second integrator 42 constituting the speed load estimator 12 of the first embodiment is represented by γ.
Then, the signal γ is focused on the subtractor 31,

[0124]

[Equation 17] However, the drive signal u is represented by (Equation 18) focusing on the adder 46 of FIG.

[0125]

(Equation 18) Therefore, from (Equation 17) and (Equation 18), the signal γ
Can be expressed by (Equation 19).

[0126]

[Equation 19] Rewriting the block diagram 30 of the speed load estimator 12 of the first embodiment shown in FIG. 2 based on (Equation 19),
A block diagram 40 of the speed load estimator 70 shown in FIG. 10 is obtained. As shown in FIG. 10, the speed control signal cv generated by the speed controller 17 (block 21) is
2 and the output of block 32 is input to the multiplier of block 33. Therefore, the drive torque estimation signal τ _est can be obtained by multiplying the speed control signal cv by the coefficient (gmn · Ktn).

Embodiment 2 Similar to Embodiment 1 described above.
The magnetic disk device estimates the disturbance torque acting on the arm 3 from the voltage signal Va generated by the voltage detector 11 and the speed control signal cv generated by the speed controller 17 by the function of the speed load estimator 70. and outputs the load estimated signal .tau.d _est. Load estimation signal .tau.d _est are input to the corrector 15 so as to cancel the disturbances .tau.d acting on the arm 3, such as a bearing friction and elastic force and inertial force.

FIG. 11 is a block diagram showing the entire configuration of the position control system when the switch 60 of the switch 18 is connected to the terminal b in the magnetic disk drive of the second embodiment. Note that components having the same functions as those of the first embodiment are denoted by the same reference numerals, and redundant description will be omitted.

The magnetic disk drive according to the second embodiment uses the speed load estimator 70 as in the first embodiment.
The disturbance caused by the inertial force experienced by the actuator 9 can be accurately detected by the vibration or shock applied from the outside, it is possible to suppress the track deviation due to disturbance by inputting this load estimation signal .tau.d _est in corrector 15 . As a result, the positioning of the magnetic head 2 on the target track is controlled with high precision. As in the first embodiment, the magnetic disk drive according to the second embodiment includes an externally applied disturbance τd
Acts as if it were added to the positioning control system through the filter having the cut-off frequency characteristic of (Equation 13) and FIG. 5, and suppresses disturbance with the first-order low-frequency cut-off characteristic at frequencies lower than the angular frequency ωo. be able to. Track displacement due to disturbance can be suppressed, and the magnetic head 2
Is precisely positioned on the target track. As a result, the magnetic disk drive according to the second embodiment of the present invention
Load as a switch command to the command terminal 20 of the switch 18
When the unload command is input, the switch 60 of the switch 18 is connected to the terminal a, and moves the magnetic head 2 to a target track on the magnetic disk 1 at a smooth speed.
Further, the magnetic head 2 can be smoothly retracted from the magnetic disk 1 to the ramp block 7. When a following command is input to the command terminal 20 of the switch 18 as a switching command, the switch 60 of the switch 18 is switched to the terminal b.
And the magnetic head 2 is positioned and controlled with high precision on the target track. When a large vibration or shock is applied while the magnetic head is on the disk and recording or reproducing data, the level detector 19 outputs the "H" level switching signal t to the switching unit 18. The switch 60 of the switch 18 is switched from the terminal b to the terminal a, and the magnetic head 2 is immediately unloaded.

Therefore, according to the magnetic disk drive of the second embodiment of the present invention, the speed movement of the head can be accurately detected by the speed load estimator 70, and the fluctuation of the friction load on the ramp block is large. In addition, stable speed control is possible, and the reliability of the load / unload operation of the magnetic head can be improved. In the following operation of the magnetic head, even if the bearing friction of the bearing 4 and the elastic force of the flexible printed circuit or the like act on the actuator 9, the influence of the disturbance load is canceled by the speed load estimator 70 and the corrector 15. Therefore, the positioning accuracy of the magnetic head can be improved. In addition, the vibration and shock applied to the magnetic disk drive are measured by a speed load estimator 70.
And the magnetic head 2 can be unloaded, so that the magnetic head and the surface of the magnetic disk are not damaged by vibration or impact, and the reliability of the magnetic disk device can be improved. it can.

The speed load estimator 70 constructed in the same manner as the block 30 in FIG. 2 is not affected by the sampling frequency of the sector servo of the magnetic disk drive. Therefore, the control band of the speed load estimator 70 can be set higher than the control band of the positioning control system.

Further, in the magnetic disk drive according to the second embodiment, the number of adders forming the speed load estimator 70 and the compensator 15 can be reduced, so that the control system is realized by hardware such as an analog circuit. Can simplify the adjustment of the circuit. Further, when the control system is realized by software, it is possible to reduce the operation time delay due to the operation processing, and it is possible to further increase the control band.

In each of the embodiments described above, the multipliers and integrators are described as being constituted by analog filters. However, the multipliers and integrators may be constituted by digital filters. Further, each part constituting the speed control system of each embodiment may be realized by software by a microcomputer.

[0134] In the magnetic disk apparatus of Embodiment 1 and Embodiment 2 of the present invention described above, by using the load estimator signal .tau.d _est generated by the speed load estimator 12,70, actually acting on the actuator is constituted so as to cancel the disturbance load τd due to friction or the like which, when the fluctuation of the frictional load on the ramp block is small, the speed estimation signal v _est only head speed control for generating a speed load estimator 12,70 using the load estimation signal .tau.d _est may be configured not used. In this case, the compensator 15 is not required, and the configuration of the magnetic disk device is simplified.

Further, in the magnetic disk devices according to the first and second embodiments of the present invention, the speed control mode of the magnetic head in loading / unloading and the positioning of the magnetic head in following are performed in response to the switching command. The control is performed by switching between the control mode and the control mode, but the control parameters of the speed load estimator 12 and the speed load estimator 70 do not need to be particularly changed according to each mode. Therefore,
The disk device of the present invention can form a control system with a simple configuration.

In each of the embodiments described above, the magnetic disk device has been described, but the present invention is not limited to this.

[0137]

As described above, according to the disk drive of the present invention, the speed load estimating means detects the head moving speed and the disturbance load due to the friction or the like received from the head retreating member such as the ramp block during the load / unload operation. Since the detection can be accurately performed, the speed control can be stably performed even if the fluctuation of the friction load is large. That is, the reliability of the head load / unload operation can be improved.

Further, according to the disk apparatus of the present invention, it is possible to switch between the moving speed control of the head and the control of the positioning to the target track in accordance with the switching command, and even after the head is smoothly loaded on the disk. The function of the speed load estimating means can compensate for fluctuations in disturbance loads such as bearing friction applied to the actuator means, elastic force of the flexible printed circuit, and inertial force applied to the actuator means due to external shock or vibration applied to the disk drive. The positioning accuracy of the head with respect to the track can be improved. At the same time, the vibration resistance of the disk device can be improved by canceling out the inertial force received by the actuator means due to external shock or vibration applied to the disk device.

Therefore, according to the disk apparatus of the present invention, when the external force acting on the actuator means greatly affects the positioning control system due to the reduction in size and weight of the actuator means, the positioning accuracy of the head can be improved. Since the track density can be increased as compared with the related art, a large-capacity disk device can be realized.

Further, at the time of recording / reproducing data to / from the disk, the level detecting means always monitors the magnitude of the load estimation signal generated by the speed load estimating means, and when the load estimation signal exceeds a predetermined value. Outputs an unload command as a switching signal and instantaneously retracts the head to the head retraction member such as a ramp block, so even if the magnitude of vibration or shock applied to the disk device from outside is large, the head collides with the disk Without damaging the head and the disk. Therefore,
ADVANTAGE OF THE INVENTION According to this invention, even if it mounts in a portable computer etc. which are easily susceptible to vibrations and shocks from the outside, it is possible to realize a disk device having high reliability against vibrations and shocks.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a magnetic disk drive according to a first embodiment of the present invention;

FIG. 2 is a block diagram showing an overall configuration of a speed control system according to the first embodiment of the present invention.

FIG. 3 is a block diagram for explaining a disturbance load estimation operation of the speed load estimator according to the first embodiment of the present invention;
And a block diagram (b) obtained by equivalently converting the block diagram of (a) and a block diagram expressing the block diagram of (a) collectively

FIG. 4 is a block diagram for explaining an operation of suppressing a disturbance load applied to the disk device according to the first embodiment of the present invention, and a block diagram obtained by equivalently converting the block diagram of FIG. b)

FIG. 5 is a cutoff frequency characteristic diagram with respect to a disturbance load applied to the disk device according to the first embodiment of the present invention;

FIG. 6A is a time waveform diagram of a fluctuation of a disturbance load applied to the disk device according to the first embodiment of the present invention and a load estimation signal output by a speed load estimator, and FIG. (B) is a time waveform diagram of the head moving speed when no is input to the corrector, and the head moving speed when the load estimation signal output from the speed load estimator is input to the corrector to cancel the fluctuation of the disturbance load. Time waveform chart (c)

FIG. 7 is a block diagram showing an overall configuration of a position control system according to the first embodiment of the present invention.

FIG. 8 (a) is a diagram showing a fluctuation of disturbance applied to the disk device according to the first embodiment of the present invention, a time waveform diagram of a load estimation signal output by the speed load estimator, and a load estimation signal output by the speed load estimator. A drive current time waveform diagram (b) showing a difference between a case where the load estimation signal is inputted to the compensator and a case where the load estimation signal is not inputted to the compensator; Time waveform diagram of a track error showing a difference between a case where the fluctuation is canceled and a case where the fluctuation of the disturbance is not canceled (c).

FIG. 9 is a block diagram showing a configuration of a magnetic disk drive according to a second embodiment of the present invention;

FIG. 10 is a block diagram showing an overall configuration of a speed control system according to a second embodiment of the present invention.

FIG. 11 is a block diagram showing an overall configuration of a position control system according to a second embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Magnetic disk 2 Magnetic head 3 Arm 4 Bearing 5 Drive coil 6 Stator 7 Ramp block (head retracting member) 8 Suspension tab 9 Actuator (Actuator means) 10 Driver (Drive means) 11 Voltage detector (Voltage detector) 12 , 70 Speed load estimator (speed load estimating means) 13 Comparator (comparing means) 14 Speed controller (speed controlling means) 15 Corrector (correcting means) 16 Position detector (position detecting means) 17 Position controller (position) Control means) 18 switch (selection means) 19 level detector (level detection means) 32, 33 first multiplier (first multiplication means) 43 first integrator (first integration means) 44 second (Second multiplying means) 34, 35 Second integrator (second integrating means) 37 Comparator (comparing means) u drive signal vr speed command signal Va voltage signal v head moving speed v _est rate estimate signal τ drive torque .tau.d disturbance load .tau.d _est load estimated signal Ia drive current Ia _est estimated current Ea induced voltage Ea _est induced voltage estimation signal Va _est voltage estimation signal β correction signal cv speed control Signal ex Position error signal cx Position control signal c Control signal

Claims (7)

[Claims] An actuator for loading / unloading a head from / to a disk; a drive for the actuator; a voltage detector for detecting a voltage generated in driving the actuator and outputting a voltage signal; Speed load estimating means for estimating a head moving speed and a magnitude of a disturbance load applied to the head from the driving signal and the voltage signal, and outputting a speed estimation signal and a load estimation signal; and a speed command signal and a speed based on the speed estimation signal. Speed control means for generating and outputting a control signal; position detection means for generating and outputting an error signal corresponding to the current position of the head from servo information prerecorded on the disk and detected by the head; and the error signal Position control means for generating and outputting a position control signal corresponding to the speed control signal and the position control signal. Signal means is selected and any of the control signals is selected and output in response to a switching command, and a level detecting means that outputs the switching signal to the selecting means in response to the load estimation signal, The drive signal is obtained by synthesizing the control signal and the load estimation signal, and unloads the head when the load estimation signal exceeds a predetermined value at the time of recording and reproducing data on the disk. A disk drive characterized in that: 2. The speed load estimating means includes: comparing means to which a voltage signal detected by the voltage detecting means is input; first multiplying means for multiplying the driving signal by a first coefficient; A second multiplication means for multiplying the output of the first multiplication means by a second coefficient, a first integration means for integrating the output of the comparison means, and an output of the second multiplication means from the output of the first multiplication means. A second integrating means for integrating a value obtained by subtracting an added value with an output of the first integrating means, wherein the comparing means compares the voltage signal with an output of the second integrating means, 2. The disk drive according to claim 1, wherein the result is output to the second multiplying means and the first integrating means. 3. An actuator for loading and unloading a head onto and from a disk, a driving unit for the actuator, a voltage detection unit for detecting a voltage generated in driving the actuator and outputting a voltage signal, and a speed. Speed control means for generating and outputting a speed control signal from a command signal and a speed estimation signal; and generating and outputting an error signal corresponding to the current position of the head from servo information prerecorded on the disk and detected by the head. A position detection unit, a position control unit that generates and outputs a position control signal corresponding to the error signal, and the speed control signal and the position control signal are input, and one of the control signals is selected according to a switching command. The head moving speed and the head speed based on the output selection means, the voltage signal and the control signal output from the selection means. Speed load estimating means for estimating the magnitude of a disturbance load applied to the load and outputting the speed estimating signal and the load estimating signal; and level detecting means for outputting the switching signal to the selecting means in response to the load estimating signal. The drive signal is obtained by synthesizing the control signal output from the selection means and the load estimation signal, and when the load estimation signal exceeds a predetermined value at the time of recording / reproducing data on the disk. Wherein the head is configured to unload the head. 4. The speed load estimating means includes: comparing means to which the voltage signal detected by the voltage detecting means is input; first multiplying means for multiplying the control signal by a first coefficient; A second multiplication means for multiplying the output of the second multiplication means by a second coefficient, a first integration means for integrating the output of the comparison means, and an output of the second multiplication means from the output of the first multiplication means. Second integrating means for integrating the subtracted value, wherein the comparing means compares the voltage signal with the output of the second integrating means, and compares the result with the second multiplying means and the first 4. The disk device according to claim 3, wherein the signal is output to the integrating means. 5. The apparatus according to claim 1, wherein when the load estimation signal exceeds a predetermined value when recording data on the disk, the recording by the head is prohibited and the head is unloaded. The disk drive according to claim 1, wherein 6. The speed load estimating means is configured to output the load estimation signal in a state where high frequency components are cut off.
The disk device according to any of the above. 7. The control band of the speed load estimating means is set to be larger than the control band of the position control means or the speed control means. The disk device according to 1.