JP2002288955A - Head positioning device, head positioning control method, head positioning control program, recording medium recording head positioning control program, and disk device using these - Google Patents

Abstract

(57) Abstract: A head positioning control means for a disk drive using a dual actuator, capable of performing head positioning control with stable operation even under the influence of frictional force based on static friction of a coarse actuator. To achieve. SOLUTION: A fine movement control section 162 for controlling the head positioning by controlling the displacement of a fine movement actuator 52 based on a position error signal, and a coarse movement control section for controlling the head positioning by a relative displacement signal corresponding to the displacement amount of the fine movement actuator 52. And a coarse control unit 161.
Has a non-linear converter 18 which has a larger gain when the amplitude of the relative displacement signal is smaller than that when the amplitude of the relative displacement signal is larger, and has a non-linear characteristic in which the relative displacement signal is amplified. Head positioning by the actuator 51 is performed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an information recording / reproducing device such as a magnetic disk device and an optical disk device.
The present invention relates to a head positioning device having a dual structure actuator, a head positioning control method, a head positioning control program, a recording medium on which a head positioning control program is recorded, and a disk device using the same.

[0002]

2. Description of the Related Art In recent years, with the development of multimedia,
There is a strong demand from the market for high-density disk drives that position the head at the target position at high speed and record and reproduce high-capacity video, audio, and text information at high speed. Various positioning techniques have been proposed. As a technique for achieving such high-speed and high-precision positioning, a method of performing servo control by making two driving mechanisms, a main driving mechanism and an auxiliary driving mechanism, cooperate with each other has attracted attention.

The main driving mechanism is to move the head supporting mechanism, the head, and the head slider by rotating the head supporting mechanism about a rotating shaft attached to the disk drive main body by a voice coil motor or the like. The main drive mechanism is mainly used for large movements such as seek operation and multiple track jumps.

The auxiliary driving mechanism is controlled by a piezo element or the like at the tip of the main driving mechanism, and has a narrow movable range but is controlled in a wide band, and drives the head and the head slider. The auxiliary drive mechanism is mainly used for performing high-speed fine positioning such as track following and one-track jump.

A mechanism having a double structure having a main drive mechanism and an auxiliary drive mechanism is generally called a double actuator or a piggyback actuator. It is called an actuator.

In a conventional disk drive, a voice coil motor (hereinafter referred to as VCM) is used as a means for moving a head.
) Is generally used. However, an actuator that moves the head at high speed across thousands or tens of thousands of tracks
There is a limit to performing head positioning control with an accuracy such as one-tenth of a track. Therefore, as described above, in the disk device, a piezo actuator that finely drives the piezo element by a control voltage, a VCM, A head positioning control system using a dual actuator equipped with an electromagnetic micro-actuator having a structure similar to that of Japanese Patent Laid-Open No.
255418).

In particular, a piezo element has both functions of a piezoelectric effect and an inverse piezoelectric effect. In other words, at the same time as position control by minute displacement using strain due to control voltage,
A minute displacement amount can be detected as a detection voltage using a voltage generated by the displacement. For this reason, an actuator control method called a self-sensing actuator using both functions has been proposed (for example,
Transactions of the Japan Society of Mechanical Engineers 64, 624, 2931-293
7 (1998-8) "Track control of beam using self-sensing actuator based on virtual bridge circuit"
reference).

In addition, a piezo element is mounted as a fine movement actuator on the head support mechanism driven by the coarse movement actuator, and high-speed and high-precision head positioning is performed by utilizing both the piezoelectric effect and the inverse piezoelectric effect of the piezo element. A controllable dual actuator control method has also been proposed (for example, Japanese Patent Application Laid-Open No. 60-35383).

A conventional disk drive having a double actuator will be described below with reference to the drawings.

FIG. 13 is a configuration diagram showing a configuration of a head positioning device in a magnetic disk device as a conventional example. In FIG. 13, a magnetic head 12 (hereinafter referred to as a head) for recording and reproducing information on a magnetic disk 11 (hereinafter referred to as a disk), which is one of disk-shaped recording media.
Are formed integrally with the tip of the head slider 13. The head slider 13 is mounted on the tip of a fine movement actuator 52, and the fine movement actuator 52 is connected to the tip of the head support mechanism 14. The head support mechanism 14 includes a rotating shaft 14 provided on the main body of the magnetic disk drive.
The head 12 is driven by a coarse movement actuator 51 centered on 0, and performs positioning of the head 12 in cooperation with a fine movement actuator 52. The coarse movement actuator 51 moves the head 12 at the distal end by rotating the head support mechanism 14 by a voice coil motor or the like, and is mainly used for large movements such as a seek operation and a plurality of track jumps. On the other hand, the fine movement actuator 52 moves the head 12 at the distal end by performing position control in a narrow range but a wide band due to displacement of a piezo element or the like, and mainly performs high-speed fine positioning such as track following and jumping of one track. Used for

The positioning mechanism in the prior art is driven and positioned based on a control signal from a control section 96 constituted by a control circuit. In FIG. 13, the fine movement actuator 52 causes the head 12 mounted on the tip end side of the head support mechanism 14 to extend the head support mechanism 14 by a drive signal from the drive circuit 64 based on the fine movement control signal u2 of the fine movement control unit 92. It is controlled so as to make a small displacement from the center position above. The coarse motion actuator 51 moves the head support mechanism 14 including the head 12 to the target track by a drive signal from the drive circuit 63 based on the coarse motion control signal u1 of the coarse motion control unit 91. The fine movement control unit 92 controls the fine movement actuator 52,
1 controls the coarse motion actuator 51, so that predetermined frequency characteristics and phase characteristics
0 and 920, the predetermined gain is
1 and 921 are set in advance.

The head 12 attached to the tip of the fine movement actuator 52 reads a head position signal y indicating the current position of the head 12 from the servo information recorded on the disk 11 in advance. This head position signal y is
This is a signal corresponding to the position Y obtained by adding the center position Y1 of the head support mechanism 14 on the extension of the coarse movement actuator 51 and the displacement Y2 from the center position Y1 to the head position of the fine movement actuator 52. Head position signal y
Is subtracted by a subtractor 95 from a target position signal r instructed to move to a target position R which is a target track, and is output as a position error signal e2. The position error signal e2 is input to the fine movement control section 92, and the position of the fine movement actuator 52 is controlled. On the other hand, the amount of displacement Y2 from the center position Y1 to the head position Y by the fine movement actuator 52 can be detected when the above-described piezo element or the like is used. Here, the fine movement actuator 5
The actual displacement amount Y2 of the minute position is represented by a relative displacement signal y2.
Has been detected as The relative displacement signal y2 is input to the coarse movement control unit 91, and the coarse movement actuator 51 is controlled.

With such a configuration, position control is performed in two operation modes, a seek operation mode in which a movement operation between tracks is performed toward a target track, and a following operation mode in which a head follows a center of the target track. It is.

In this conventional example, the fine movement actuator 52 is controlled in accordance with the position error signal e2, and the coarse movement actuator 51 is controlled in accordance with the relative displacement signal y2 which detects the displacement Y2 of the fine movement actuator 52. The fine movement actuator 52 and the coarse movement actuator 51 cooperate to perform the movement between tracks and the track following operation.

According to the above configuration, when the head reaches the target track by a seek operation or the like, the head positioning control can be performed such that the displacement Y2 of the fine movement actuator 52 is always zero. Therefore, in the track following operation such as the following operation, the track following operation can always be performed in the most stable state with the displacement Y2 of the fine movement actuator 52 centered at zero. Therefore, the track following operation is not performed in a state where the fine movement actuator 52 is displaced.
It is possible to prevent the fine movement actuator 52 from exceeding the operation range and becoming uncontrollable or unstable and abnormally oscillating.

[0016]

However, in the configuration of the double actuator shown in the conventional example, the effect of the frictional force based on the static friction of the coarse actuator 51 is not considered in the head positioning control, so that the head positioning control is smooth. There has been a problem that a moving operation becomes difficult or a state where servo control is not performed accurately occurs.

In the double actuator shown in the conventional example, the head supporting mechanism 14 is supported by a rotating shaft 140 so as to be movable in the radial direction of the disk 11. In particular, so that positioning can be performed with higher accuracy,
Positioning is performed by the cooperative control of the dual actuator, but regardless of whether or not the cooperative control is performed, the positioning accuracy is generally degraded if there is the effect of friction between the head support mechanism and the rotating shaft. There was a problem of doing. For example, in FIG. 13, when the rotation shaft 140 starts moving from a state in which the head support mechanism 14 is stopped, the driving force exceeds the frictional force based on the static friction between the rotation shaft 140 and the head support mechanism 14. is necessary. After the movement of the head support mechanism 14 is started, a frictional force based on kinetic friction acts between the rotating shaft 140 and the head support mechanism 14. Generally, in order to move a movable portion such as the head support mechanism 14, static friction requires a larger driving force than dynamic friction.

Therefore, in a mechanism for performing the moving operation using the rotating shaft 140, smooth moving operation is difficult due to the difference between the static friction and the dynamic friction, and the servo control may not be accurately performed. There is. Such a problem with respect to static friction and dynamic friction is not limited to the magnetic disk device shown in the conventional example, but has a similar problem in an optical disk device (for example, Japanese Patent Application Laid-Open No. 9-312026).

Hereinafter, in the conventional example shown in FIG.
An operation in which static friction acts on 0 will be described. For example, the position control up to the target track specified by the target position signal r is performed by the following operation. First, when a target track is specified, a difference between the head position signal y indicating the current position and the target position signal r occurs, and this difference is input to the fine movement control unit 92 as a position error signal e2. Since the fine movement control unit 92 has a quick response, the fine movement actuator 52
Is displaced in the target track direction. Further, the displacement amount Y2 of the fine movement actuator 52 is detected as a relative displacement signal y2 and input to the coarse movement control unit 91. However, when static friction occurs, a larger driving force is required as compared to when the head support mechanism 14 moves. Therefore, in the case of a seek operation over a long distance, the seek operation is started with a time delay until the output of the coarse movement control unit 91 becomes a driving force exceeding the static friction force. On the other hand, in the case of a seek operation or a following operation for a short distance, the displacement amount of the fine movement actuator 52 does not become so large. For this reason, when the static friction force is large, the output of the coarse motion control unit 91 does not increase to a driving force exceeding the static friction force, and the head support mechanism 14 continues to be stationary. When this happens,
The fine movement actuator 52 has disadvantages such as an oscillation state in which the displacement in the target track direction and a displacement in the direction of the displacement amount zero due to the reduced position error signal e2 as a result, and a state in which the fine movement actuator 52 is displaced to an unintended position. Is generated.

In order to solve such a problem, the rotating shaft 1
Although it is possible to solve the problem to some extent by using a bearing having a small friction for 40, it is difficult to cope with friction due to aging or the like, and there is a problem that the cost of mechanical parts is increased. Furthermore, with the miniaturization of portable terminals and the like, the influence of friction cannot be ignored, and there is a limit in mechanical measures. On the other hand, there has been proposed a method of compensating for this friction by devising a servo control system. Although not limited to a double actuator as shown in the conventional example, a method using a frictional force estimator (for example, JP-A-9-231701), a method for measuring and using the acceleration of an actuator (for example, JP-A-2-260287
Japanese Patent Application Laid-Open No. 10-255285, and a method of measuring and using a change in a drive signal to an actuator (for example, Japanese Patent Application Laid-Open No. 10-255285). The stop state due to the static friction is determined by these methods, and at the time of the stop, the drive signal that overcomes the static friction force is driven to compensate for the static friction. However, it is necessary to provide a determination circuit such as a frictional force estimator, an acceleration sensor, and a drive signal change detection circuit, and a drive control circuit that switches the drive signal based on the determination circuit, thereby increasing costs and complicating the circuit. There were problems such as becoming.

An object of the present invention is to solve such a problem. By adding a simple element to the servo control system of the dual actuator described in the conventional example, the coarse actuator can be stopped. A head positioning device, a head positioning control method, a head positioning control program, a head positioning control program, a recording medium on which a head positioning control program is recorded, and a recording medium using the same, capable of performing head positioning control with stable operation even under the influence of frictional force based on friction A disk device is provided.

[0022]

In order to solve the above-mentioned problems, a head positioning device according to the present invention is provided with a fine actuator for mounting a head for recording and reproducing information on a disk-shaped recording medium and performing fine positioning of the head. A coarse movement actuator that moves a head support mechanism equipped with a fine movement actuator to roughly position the head, and a control unit that controls displacement of the fine movement actuator and movement of the head by the coarse movement actuator. Furthermore, the control unit controls the displacement of the fine movement actuator based on a position error that is a distance between the target position for positioning the head at the target position and the current position of the head,
A value corresponding to the displacement amount of the fine movement actuator is detected as a relative displacement value, and when the absolute value of the relative displacement value is small, the relative displacement value is nonlinearly converted with a larger gain than when the absolute value of the relative displacement value is large, and the nonlinear displacement is calculated. This is a configuration having a head positioning control function for controlling the movement of the head by the coarse movement actuator based on the result of the conversion.

According to this configuration, at the start of a seek operation in which static friction occurs or at the time of a following operation, the amount of control to the coarse actuator is increased by the non-linear conversion function as compared with the related art. A force can be applied to the coarse actuator, and the effect of static friction can be suppressed. That is, at the start of the seek operation or the following operation in which the static friction occurs, first, the relative displacement value from the fine movement actuator is very small. The function of the non-linear conversion is set so that when the absolute value of the relative displacement value is small, the relative displacement value is non-linearly converted with a larger gain than when the absolute value of the relative displacement value is large. For this reason, when static friction occurs such that the relative displacement value is minute, the control amount for the coarse motion actuator can be increased. Therefore, when static friction is generated, it is possible to apply a larger driving force to the coarse motion actuator than before. As a result, the head positioning control can be performed with a stable operation even under the influence of the frictional force based on the static friction of the coarse actuator. Also, as a function of nonlinear conversion, when the absolute value of the relative displacement value is large,
A gain equivalent to the conventional one can be set. For this reason, when the fine movement actuator is displaced by an external force due to an external impact, etc., and the relative displacement value increases, the gain becomes equivalent to the conventional one, and the characteristics are almost the same as the conventional one, and it is stable Nature can be secured.

Also, in the head positioning apparatus according to the present invention, the control unit may control a difference between a target position signal for positioning the head at the target position and a head position signal based on servo information on a recording medium reproduced by the head. Is input as a position error signal, and a fine movement control unit that controls the displacement of the fine movement actuator based on the position error signal, and a relative displacement signal corresponding to the amount of displacement of the fine movement actuator are input to control the movement of the head by the coarse movement actuator And a coarse movement control unit. Further, the relative displacement signal is used as the conversion input signal, and when the amplitude of the conversion input signal is small, the result obtained by amplifying the conversion input signal with a larger gain than when the amplitude of the conversion input signal is large is used as the conversion output signal. The coarse movement control unit has a non-linear converter having the following configuration. The coarse movement control unit controls the movement of the head by the coarse movement actuator based on the converted output signal.

According to this configuration, at the start of a seek operation in which static friction occurs or at the time of a following operation, the amount of control to the coarse actuator is increased by the non-linear converter as compared with the related art, and as a result, a larger driving force than the related art is obtained. Can be added to the coarse actuator, and the effect of static friction can be suppressed. That is, at the start of the seek operation or the following operation in which static friction occurs, first, the relative displacement signal from the fine movement actuator is very small, and the conversion input signal is also very small. The non-linear converter is set to perform non-linear conversion of the converted input signal with a larger gain when the amplitude of the converted input signal is smaller than when the amplitude of the converted input signal is larger. For this reason, when static friction occurs, such as when the conversion input signal corresponding to the relative displacement signal is minute, the control amount for the coarse actuator can be increased. Therefore, when static friction is generated, it is possible to apply a larger driving force to the coarse motion actuator than before. As a result, the head positioning control can be performed with a stable operation even under the influence of the frictional force based on the static friction of the coarse actuator. Further, when the amplitude of the relative displacement signal is large, the nonlinear converter can set the same gain as the conventional one. For this reason, when the fine movement actuator is displaced by an external force due to an external impact, etc., and the relative displacement signal becomes large, the gain becomes equivalent to the conventional one, and the characteristics are almost the same as the conventional one, and it is stable Nature can be secured. Furthermore, since the effect of static friction is suppressed by using the non-linear characteristics, switching can be performed easily and easily without using a detection circuit or switching circuit that detects and controls the state of the head acceleration and other conditions. It can also be realized without the influence of time or the influence of circuit delay time.

Also, in the head positioning apparatus according to the present invention, the control unit may control the difference between the target position data for positioning the head at the target position and the head position data from the servo information on the recording medium reproduced by the head. Is input as position error data, and a fine movement control unit that controls the displacement of the fine movement actuator based on the position error data, and relative displacement data corresponding to the displacement amount of the fine movement actuator are input,
A coarse movement control unit for controlling the movement of the head by the coarse movement actuator. Further, the relative displacement data is used as the conversion input data, and when the absolute value of the conversion input data is small, the result of the multiplication multiplied by the conversion input data by a larger multiplier than when the absolute value of the conversion input data is large is used as the conversion output data. The coarse motion control unit has a non-linear converter having the following non-linear characteristics, and the coarse motion control unit is configured to control the movement of the head by the coarse motion actuator based on the converted output data.

According to this configuration, at the start of a seek operation in which static friction occurs or at the time of a following operation, the amount of control to the coarse actuator is increased by the non-linear converter as compared with the related art, and as a result, a larger driving force than the related art is obtained. Can be added to the coarse actuator, and the effect of static friction can be suppressed. That is, at the start of a seek operation or a following operation in which static friction occurs, first, the relative displacement data from the fine movement actuator is minute, and the conversion input data is also minute. The nonlinear converter sets a nonlinear conversion characteristic that multiplies the conversion input data by a larger multiplier when the absolute value of the conversion input data is small compared to when the absolute value of the conversion input data is large. For this reason, when static friction is generated such that the conversion input data corresponding to the relative displacement data is minute, the control amount to the coarse motion actuator can be increased. Therefore, when static friction is generated, it is possible to apply a larger driving force to the coarse motion actuator than before. As a result, the head positioning control can be performed with a stable operation even under the influence of the frictional force based on the static friction of the coarse actuator.
When the absolute value of the relative displacement data is large, the nonlinear converter can set a multiplier equivalent to the gain equivalent to the conventional one. For this reason, when the fine movement actuator is displaced by an external force due to an external impact, etc., and the relative displacement data becomes large, the gain becomes the same as the conventional one, and it is stable by giving almost the same characteristics as the conventional Nature can be secured. Furthermore, since the effect of static friction is suppressed by using the non-linear characteristics, switching can be performed easily and easily without using a detection circuit or switching circuit that detects and controls the state of the head acceleration and other conditions. It can also be realized without the influence of time or the influence of circuit delay time. Furthermore, by setting the data for the non-linear conversion in advance as a non-linear conversion table, it is possible to perform accurate, flexible, and smooth control, such as continuously changing the multiplier or making the multiplier constant at a certain level. .

Further, in the head positioning apparatus according to the present invention, the control unit controls the micro-actuator and the coarse-movement actuator, a memory for storing a program for operating the microprocessor, and an operation of the microprocessor. And a program for causing the Further, the program is configured to have a head positioning control program for realizing a head positioning control function by reading and executing the program by the microprocessor.

With this configuration, the head positioning control program read from the memory is executed by the microprocessor, so that at the start of a seek operation in which static friction occurs or at the time of a following operation, a nonlinear conversion function is used.
The control amount for the coarse actuator becomes larger than before, and as a result, it becomes possible to apply a larger driving force to the coarse actuator than before, and it is possible to suppress the influence of static friction. That is, at the start of the seek operation or the following operation in which the static friction occurs, first, the relative displacement value from the fine movement actuator is very small. The function of the non-linear conversion is set so that when the absolute value of the relative displacement value is small, the relative displacement value is non-linearly converted with a larger gain than when the absolute value of the relative displacement value is large. For this reason, when static friction occurs such that the relative displacement value is minute, the control amount for the coarse motion actuator can be increased. Therefore, when static friction is generated, it is possible to apply a larger driving force to the coarse motion actuator than before. As a result, the head positioning control can be performed with a stable operation even under the influence of the frictional force based on the static friction of the coarse actuator. As a function of the nonlinear conversion, when the absolute value of the relative displacement value is large, a gain equivalent to that of the related art can be set. For this reason, when the fine movement actuator is displaced by an external force due to an external impact, etc., and the relative displacement value increases, the gain becomes equivalent to the conventional one, and the characteristics are almost the same as the conventional one, and it is stable Nature can be secured. In addition, since the effect of static friction is suppressed by using the non-linear characteristic, it can be easily used without using a function as a detection means or switching means in a system that detects and controls the state such as head acceleration. It can also be realized. Furthermore, by setting the data for nonlinear conversion in advance as a nonlinear conversion table, the multiplier can be changed continuously, or at a certain level, the multiplier can be kept constant.
Flexible and smooth control can be performed.

Further, the head positioning device of the present invention has a head positioning control program for causing the microprocessor to function as fine movement control means, nonlinear conversion means, and coarse movement control means. The fine movement control means uses the difference between target position data for positioning the head at the target position and head position data from servo information on the recording medium reproduced by the head as position error data, and performs fine movement based on the position error data. Fine movement control data for controlling the displacement of the actuator is derived, and the fine movement actuator is driven based on the fine movement control data. The nonlinear conversion means uses data corresponding to the displacement amount of the fine movement actuator as relative displacement data, and uses the relative displacement data as conversion input data when the absolute value of the conversion input data is small as compared with when the absolute value of the conversion input data is large. It has non-linear characteristics in which the result of multiplication obtained by multiplying conversion input data by a multiplier is converted output data. The coarse motion control means derives coarse motion control data for controlling the movement of the head by the coarse motion actuator based on the converted output data, and drives the coarse motion actuator based on the coarse motion control data.

With this configuration, the head positioning control program read from the memory is executed by the microprocessor, so that at the time of starting a seek operation in which static friction occurs or at the time of a following operation, the function as the non-linear conversion means is applied to the coarse actuator. Becomes larger than before, and as a result, it becomes possible to apply a larger driving force to the coarse motion actuator than before, and it is possible to suppress the influence of static friction. That is, at the start of a seek operation or a following operation in which static friction occurs, first, the relative displacement data from the fine movement actuator is minute, and the conversion input data is also minute. The function as the non-linear conversion means sets a non-linear conversion characteristic of multiplying the conversion input data by a larger multiplier when the absolute value of the conversion input data is smaller than when the absolute value of the conversion input data is higher. For this reason, when static friction occurs such that the conversion input data corresponding to the relative displacement data is minute,
The control amount for the coarse actuator can be increased. Therefore, when static friction is generated, it is possible to apply a larger driving force to the coarse motion actuator than before. As a result, the head positioning control can be performed with a stable operation even under the influence of the frictional force based on the static friction of the coarse actuator. Further, the function as the non-linear conversion means can set a multiplier equivalent to a gain equivalent to the conventional one when the absolute value of the relative displacement data is large. For this reason, when the fine movement actuator is displaced by an external force due to an external impact, etc., and the relative displacement data becomes large, the gain becomes the same as the conventional one, and it is stable by giving almost the same characteristics as the conventional Nature can be secured. Furthermore, since the effect of static friction is suppressed by using the non-linear characteristic, it can be easily used without using a function as a detecting means or switching means in a system that detects and controls the state such as head acceleration. It can also be realized.

Further, the head positioning control device of the present invention has a head positioning control program for causing the microprocessor to execute the following steps. Setting a difference between target position data for positioning the head at the target position and head position data from servo information on a recording medium reproduced by the head as position error data; Deriving fine movement control data for controlling the displacement of the fine movement actuator based on the position error data; Driving the fine movement actuator based on the fine movement control data. Inputting relative displacement data corresponding to the displacement amount of the fine movement actuator. Using the relative displacement data as the conversion input data, when the absolute value of the conversion input data is small, the result of multiplication multiplied by the conversion input data with a larger multiplier than when the absolute value of the conversion input data is large is used as the conversion output data, The step of performing a non-linear transformation with non-linear characteristics. Driving the coarse actuator based on the converted output data.

With this configuration, the head positioning control program read from the memory is executed by the microprocessor, so that at the start of a seek operation or a following operation in which static friction occurs, a step of performing a non-linear conversion allows the coarse movement actuator to be operated. The control amount becomes larger than before, and as a result, it becomes possible to apply a larger driving force to the coarse motion actuator than before, and it is possible to suppress the influence of static friction. That is, at the start of a seek operation or a following operation in which static friction occurs,
First, the relative displacement data from the fine movement actuator is minute, and the conversion input data is also minute. The step of performing nonlinear conversion sets a nonlinear conversion characteristic of multiplying the conversion input data by a larger multiplier when the absolute value of the conversion input data is smaller than when the absolute value of the conversion input data is higher. For this reason, when static friction is generated such that the conversion input data corresponding to the relative displacement data is minute, the control amount to the coarse motion actuator can be increased. Therefore, when static friction is generated, it is possible to apply a larger driving force to the coarse motion actuator than before. As a result, the head positioning control can be performed with a stable operation even under the influence of the frictional force based on the static friction of the coarse actuator. In addition, when the absolute value of the relative displacement data is large as a step of performing the non-linear conversion, a multiplier equivalent to a gain equivalent to that of the related art can be set. For this reason, when the fine movement actuator is displaced by an external force due to an external impact, etc., and the relative displacement data becomes large, the gain becomes the same as the conventional one, and it is stable by giving almost the same characteristics as the conventional Nature can be secured. Furthermore, because the effect of static friction is suppressed using the nonlinear characteristics,
It is also possible to simply realize without using a step as a detecting means or a switching means in a method of detecting and controlling the state such as the acceleration of the head.

A head positioning control program according to the present invention includes a fine actuator for mounting a head for recording / reproducing information on a disk-shaped recording medium and for performing fine positioning of the head, and a head support mechanism for mounting the fine actuator. This is a program for controlling a head positioning device including a coarse movement actuator for moving and coarsely positioning the head, and a control unit for controlling displacement of the fine movement actuator and movement of the head by the coarse movement actuator. Further, the present head positioning control program is configured to cause the control unit to function as fine movement control means, non-linear conversion means, and coarse movement control means. The fine movement control means uses the difference between target position data for positioning the head at the target position and head position data from servo information on the recording medium reproduced by the head as position error data, and performs fine movement based on the position error data. Fine movement control data for controlling the displacement of the actuator is derived, and the fine movement actuator is driven based on the fine movement control data. The non-linear conversion means uses data corresponding to the displacement amount of the fine movement actuator as relative displacement data, and uses the relative displacement data as conversion input data. When the absolute value of the conversion input data is small, it is smaller than when the absolute value of the conversion input data is large. It has a nonlinear characteristic in which the result of multiplication obtained by multiplying the conversion input data by a large multiplier is converted output data. The coarse motion control means derives coarse motion control data for controlling the movement of the head by the coarse motion actuator based on the converted output data, and drives the coarse motion actuator based on the coarse motion control data.

With this configuration, when the head positioning control program is executed by the microprocessor, at the start of a seek operation or a following operation in which static friction occurs, the control amount to the coarse actuator is controlled by the function as the nonlinear conversion means. As a result, it becomes possible to apply a larger driving force to the coarse motion actuator than before, and it is possible to suppress the influence of static friction. That is, at the start of a seek operation or a following operation in which static friction occurs, first, the relative displacement data from the fine movement actuator is minute, and the conversion input data is also minute. The function as the non-linear conversion means sets a non-linear conversion characteristic of multiplying the conversion input data by a larger multiplier when the absolute value of the conversion input data is smaller than when the absolute value of the conversion input data is higher. For this reason,
When static friction is generated such that the conversion input data corresponding to the relative displacement data is minute, the control amount to the coarse actuator can be increased. Therefore, when static friction is generated, it is possible to apply a larger driving force to the coarse motion actuator than before. As a result, the head positioning control can be performed with a stable operation even under the influence of the frictional force based on the static friction of the coarse actuator. Further, the function as the non-linear conversion means can set a multiplier equivalent to a gain equivalent to the conventional one when the absolute value of the relative displacement data is large. For this reason, when the fine movement actuator is displaced by an external force due to an external impact, etc., and the relative displacement data becomes large, the gain becomes the same as the conventional one, and it is stable by giving almost the same characteristics as the conventional Nature can be secured. Furthermore, since the effect of static friction is suppressed by using the non-linear characteristic, it can be easily used without using a function as a detecting means or switching means in a system that detects and controls the state such as head acceleration. It can also be realized.

Further, the head positioning method of the present invention comprises moving a fine actuator for mounting a head for recording and reproducing information on a disk-shaped recording medium and finely positioning the head, and moving a head support mechanism on which the fine actuator is mounted. This is a method for controlling a head positioning device including a coarse actuator for coarsely positioning the head and a control unit for controlling the displacement of the fine actuator and the movement of the head by the coarse actuator.
Further, the present head positioning method has a configuration in which the control unit executes the following steps. A step of setting a difference between target position data for positioning the head at a target position and head position data from servo information on the recording medium reproduced by the head as position error data. Deriving fine movement control data for controlling the displacement of the fine movement actuator based on the position error data; Driving the fine movement actuator based on the fine movement control data. Inputting relative displacement data corresponding to the displacement amount of the fine movement actuator. The relative displacement data is used as the conversion input data, and when the absolute value of the conversion input data is small, the result of multiplication obtained by multiplying the conversion input data by a larger multiplier than when the absolute value of the conversion input data is large is used as the conversion output data. Step of performing nonlinear transformation with characteristics. Driving the coarse actuator based on the converted output data.

With this configuration, by executing the present head positioning method, at the start of a seek operation in which static friction occurs or at the time of a following operation, a step of performing a non-linear conversion reduces the control amount to the coarse motion actuator as compared with the conventional method. As a result, it becomes possible to apply a larger driving force to the coarse motion actuator than before, and it is possible to suppress the influence of static friction. That is, at the start of a seek operation or a following operation in which static friction occurs, first, the relative displacement data from the fine movement actuator is minute, and the conversion input data is also minute. The step of performing nonlinear conversion sets a nonlinear conversion characteristic of multiplying the conversion input data by a larger multiplier when the absolute value of the conversion input data is smaller than when the absolute value of the conversion input data is higher. For this reason, when static friction is generated such that the conversion input data corresponding to the relative displacement data is minute, the control amount to the coarse motion actuator can be increased. Therefore, when static friction is generated, it is possible to apply a larger driving force to the coarse motion actuator than before. As a result, the head positioning control can be performed with a stable operation even under the influence of the frictional force based on the static friction of the coarse actuator. In addition, when the absolute value of the relative displacement data is large as a step of performing the non-linear conversion, a multiplier equivalent to a gain equivalent to that of the related art can be set.
For this reason, when the fine movement actuator is displaced by an external force due to an external impact, etc., and the relative displacement data becomes large, the gain becomes the same as the conventional one, and it is stable by giving almost the same characteristics as the conventional Nature can be secured. further,
Since the effect of static friction is suppressed using nonlinear characteristics, it can be easily realized without using steps as detection means or switching means in a method that detects and controls the state such as head acceleration. It is also possible.

The head positioning control program of the present invention is configured as a head positioning control program for executing the above-described head positioning control method.

With this configuration, the head positioning control program is executed by the microprocessor, so that at the start of the seek operation or the following operation in which the static friction occurs, the step of performing the non-linear conversion reduces the control amount to the coarse actuator. As compared with the related art, the number of the actuators becomes larger, and as a result, it becomes possible to apply a larger driving force to the coarse motion actuator, and it is possible to suppress the influence of the static friction. That is, at the start of a seek operation or a following operation in which static friction occurs, first, the relative displacement data from the fine movement actuator is minute, and the conversion input data is also minute. The step of performing nonlinear conversion sets a nonlinear conversion characteristic of multiplying the conversion input data by a larger multiplier when the absolute value of the conversion input data is smaller than when the absolute value of the conversion input data is higher. For this reason, when static friction is generated such that the conversion input data corresponding to the relative displacement data is minute, the control amount to the coarse motion actuator can be increased. Therefore, when static friction is generated, it is possible to apply a larger driving force to the coarse motion actuator than before. As a result, the head positioning control can be performed with a stable operation even under the influence of the frictional force based on the static friction of the coarse actuator.
In addition, when the absolute value of the relative displacement data is large as a step of performing the non-linear conversion, a multiplier equivalent to a gain equivalent to that of the related art can be set. For this reason, when the fine movement actuator is displaced by an external force due to an external impact, etc., and the relative displacement data becomes large, the gain becomes the same as the conventional one, and it is stable by giving almost the same characteristics as the conventional Nature can be secured. Furthermore, since the effect of static friction is suppressed using the non-linear characteristics, it is easy to use a method that detects and controls the state such as the acceleration of the head and does not use steps as detection means or switching means. It can also be realized.

A recording medium according to the present invention in which a head positioning control program is recorded has an area in which the above-described head positioning control program is recorded, and has a machine-readable configuration.

With this configuration, by executing the head positioning control program read from the recording medium, at the start of a seek operation or a following operation in which static friction occurs, a function as a non-linear conversion means or a step of performing a non-linear conversion is performed. Thus, the control amount for the coarse actuator becomes larger than before, and as a result, it becomes possible to apply a larger driving force to the coarse actuator than before, and it is possible to suppress the influence of static friction.
That is, at the start of a seek operation or a following operation in which static friction occurs, first, the relative displacement data from the fine movement actuator is minute, and the conversion input data is also minute.
The function as the non-linear conversion means or the step of performing the non-linear conversion is to set a non-linear conversion characteristic for multiplying the conversion input data by a larger multiplier when the absolute value of the conversion input data is small than when the absolute value of the conversion input data is high. ing. For this reason, when static friction is generated such that the conversion input data corresponding to the relative displacement data is minute, the control amount to the coarse motion actuator can be increased. Therefore, when static friction is generated, it is possible to apply a larger driving force to the coarse motion actuator than before. As a result, the head positioning control can be performed with a stable operation even under the influence of the frictional force based on the static friction of the coarse actuator. In addition, when the absolute value of the relative displacement data is large, a multiplier equivalent to a gain equivalent to that of the related art can be set as a function as the nonlinear conversion means or as a step of performing the nonlinear conversion. For this reason, when the fine movement actuator is displaced by an external force due to an external impact, etc., and the relative displacement data becomes large, the gain becomes the same as the conventional one, and it is stable by giving almost the same characteristics as the conventional Nature can be secured.

Further, in the disk device of the present invention, a head for recording and reproducing information on a disk-shaped recording medium is mounted, and a fine actuator for fine positioning of the head and a head support mechanism for mounting the fine actuator are moved. A coarse actuator for coarsely positioning the head and a control unit for controlling displacement of the fine actuator and movement of the head by the coarse actuator are provided. Further, the control unit is provided with a microprocessor capable of controlling the fine movement actuator and the coarse movement actuator, and input data is input as conversion input data, and when the absolute value of the conversion input data is small, compared with when the absolute value of the conversion input data is large. A non-linear conversion table having a non-linear characteristic with a multiplication result obtained by multiplying the conversion input data by a large multiplier as a conversion output data, a memory for storing a program for operating the microprocessor, and a memory for operating the microprocessor. With the program. Further, this program has a configuration in which a microprocessor reads and executes the program, thereby causing the control unit to function as a fine movement control unit, a non-linear conversion unit, and a coarse movement control unit. The fine movement control means uses the difference between target position data for positioning the head at the target position and head position data from servo information on the recording medium reproduced by the head as position error data, and performs fine movement based on the position error data. Fine movement control data for controlling the displacement of the actuator is derived, and the fine movement actuator is driven based on the fine movement control data. The non-linear conversion means sets data corresponding to the amount of displacement of the fine movement actuator as relative displacement data, sets the relative displacement data as conversion input data, and sets the result of conversion by the non-linear conversion table as conversion output data. The coarse motion control means derives coarse motion control data for controlling the movement of the head by the coarse motion actuator based on the converted output data, and drives the coarse motion actuator based on the coarse motion control data.

According to this configuration, the head positioning control program read from the memory is executed by the microprocessor, so that at the time of starting a seek operation or a following operation in which static friction occurs, a function as a non-linear conversion means is applied to the coarse actuator. Becomes larger than before, and as a result, it becomes possible to apply a larger driving force to the coarse motion actuator than before, and it is possible to suppress the influence of static friction. That is, at the start of a seek operation or a following operation in which static friction occurs, first, the relative displacement data from the fine movement actuator is minute, and the conversion input data is also minute. The function as the non-linear conversion means sets a non-linear conversion characteristic of multiplying the conversion input data by a larger multiplier when the absolute value of the conversion input data is smaller than when the absolute value of the conversion input data is higher. For this reason, when static friction occurs such that the conversion input data corresponding to the relative displacement data is minute,
The control amount for the coarse actuator can be increased. Therefore, when static friction is generated, it is possible to apply a larger driving force to the coarse motion actuator than before. As a result, the head positioning control can be performed with a stable operation even under the influence of the frictional force based on the static friction of the coarse actuator. Further, when the absolute value of the relative displacement data is large, a multiplier equivalent to a gain equivalent to that of the related art can be set as a function as the nonlinear conversion means. For this reason,
If the fine movement actuator is displaced by an external force due to an external impact, etc., and the relative displacement data becomes large,
The gain is the same as the conventional one, and the stability can be ensured by giving almost the same characteristics as the conventional one. In addition, since the effect of static friction is suppressed by using the non-linear characteristic, it can be easily used without using a function as a detection means or switching means in a system that detects and controls the state such as head acceleration. It can also be realized. Furthermore, since data for nonlinear conversion can be set in the nonlinear conversion table in advance,
Accurate, flexible, and smooth control can be performed, for example, by changing the multiplier continuously, or at a certain level, by keeping the multiplier constant.

Further, a disk drive according to the present invention is configured to include the above-described head positioning device.

With this configuration, it is possible to provide a disk device capable of performing head positioning control while suppressing the influence of static friction.

The disk drive according to the present invention has a configuration using the above-described head positioning control method.

With this configuration, it is possible to provide a disk device capable of performing head positioning control while suppressing the influence of static friction.

Further, the disk device of the present invention has a configuration including the above-described head positioning control program.

With this configuration, it is possible to provide a disk device capable of performing head positioning control while suppressing the influence of static friction.

The disk device of the present invention is provided with a machine-readable recording medium having an area in which the above-described head positioning control program is recorded.

With this configuration, it is possible to provide a disk device capable of performing head positioning control while suppressing the influence of static friction.

[0052]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of a head positioning device, a head positioning control method, a head positioning control program, a recording medium on which a head positioning control program is recorded, and a disk device using the same according to the present invention will be described. This will be described with reference to the drawings, taking a disk device as an example.

(First Embodiment) FIG. 1 is a configuration diagram showing a configuration of a head positioning device according to a first embodiment of the present invention. In FIG. 1, a magnetic head 12 (hereinafter, referred to as a head) for recording and reproducing information on a magnetic disk 11 (hereinafter, referred to as a disk), which is one of disk-shaped recording media, is integrated with a tip of a head slider 13. Is formed. The head slider 13 is mounted on the tip of the fine actuator 52,
2 is connected to the tip of the head support mechanism 14.
The head support mechanism 14 is driven by a coarse movement actuator 51 about a rotation shaft 140 provided on the magnetic disk drive main body, and performs positioning of the head 12 in cooperation with a fine movement actuator 52. As described above, the configuration of the positioning mechanism in the present embodiment is a dual actuator configuration of the coarse actuator 51 and the fine actuator 52. The coarse movement actuator 51 rotates the head support mechanism 14 by a voice coil motor or the like,
The tip head 12 is moved, and is mainly used for a large movement such as a seek operation or a plurality of track jumps.
On the other hand, the fine movement actuator 52 moves the head 12 at the distal end by performing position control in a narrow range but a wide band due to displacement of a piezo element or the like, and mainly performs high-speed fine positioning such as track following and jumping of one track. Used for

The positioning mechanism in the present embodiment is driven and positioned based on a control signal from a control section 16 constituted by a control circuit. The control unit 16 generates a control signal based on a signal corresponding to the amount of displacement of the fine movement actuator 52, servo information read from the head 12, target position information instructed to perform a required positioning operation, and the like. The control signal is supplied to a control circuit including a subtractor 95, a coarse movement control unit 161 including a phase compensation circuit 610 and a non-linear converter 18, and a fine movement control unit 162 including a phase compensation circuit 620 and an amplifier 621. Generated. The control signal is converted into a drive signal by the drive circuit 63 to drive the coarse actuator 51, and converted to a drive signal by the drive circuit 64 to drive the fine actuator 52 to perform servo control of both actuators.

As shown in FIG. 1, the fine movement actuator 52 is displaced in both directions of the inner circumference and the outer circumference of the disk 11 with the position on the extension line of the head support mechanism 14 indicated by the broken line a as the center position Y1. Twelve minute positionings are performed. Here, the head 12 is moved from the center position Y1.
The position up to the position is indicated by the displacement amount Y2. In the present embodiment, the position of the coarse movement actuator 51, that is, the center position Y1, and the displacement Y2 of the fine movement actuator 52 are combined as the head position Y of the head 12,
Is moved to the target position R, and positioning is performed so as to follow the target track at the target position R.

FIG. 2 is a block diagram showing a configuration of a servo control system for controlling the dual actuator of the present embodiment shown in FIG. Here, in order to easily explain the servo control system of the present embodiment, a description of the mechanical structure of the disk device will be omitted, and a description will be given of a block diagram in which the servo control system is modeled. In FIG. 2, the same components as those in FIG. 1 are denoted by the same reference numerals. 2, the fine movement actuator 52 controls the displacement corresponding to the displacement amount Y2 shown in FIG. 1 based on the fine movement control signal u2 from the fine movement control unit 162, and moves the head 12 minutely by displacing from the center position Y1. Move only the correct position. The coarse movement actuator 51 receives the coarse movement control signal u1 from the coarse movement control unit 161.
The head support mechanism 14 including the head 12 is moved to the target position R shown in FIG. Fine movement control unit 16
The reference numeral 2 designates a predetermined frequency characteristic and a predetermined phase characteristic in the phase compensation circuit 620 and a predetermined gain in the amplifier 621 as a predetermined amplification factor in order to control the fine movement actuator 52. Here, the phase compensation circuit 620 outputs the signal from the amplifier 621.
However, the configuration may be reversed, or the configuration may be the same with an operational amplifier or the like, as long as the predetermined frequency characteristic, phase characteristic and gain can be set.

The coarse movement control section 161 sets a predetermined frequency characteristic and a predetermined phase characteristic in the phase compensation circuit 610 and a predetermined gain in the non-linear converter 18 in order to control the coarse movement actuator 51. As will be described later in detail, the non-linear converter 18 has a non-linear characteristic of amplifying and outputting the converted input signal ui with a different gain according to the converted input signal ui.

The head 12 attached to the tip of the fine movement actuator 52 reads the head position data indicating the current position of the head 12, that is, the head position data corresponding to the head position Y, from the servo information recorded on the disk 11. In FIG. 2, the head position data is referred to as a head position signal y.
The virtual adder 94 adds the virtual signal y1 of the position Y1 of the head 12 and the relative displacement signal y2 corresponding to the displacement Y2 by the fine motion actuator 52 to form a head position signal y. Head position signal y
Is subtracted by the subtractor 95 from the target position signal r corresponding to the target position R instructed to move to the target track. The difference resulting from this subtraction is output as a position error signal e2 indicating a position error. The position error signal e2 is input to the fine movement controller 162, and the position of the fine movement actuator 52 is controlled. On the other hand, the displacement Y2 of the head position by the fine movement actuator 52 can be detected when a piezo element or the like is used as described in the conventional example. Here, a detection signal that detects the actual displacement Y2 of the fine movement actuator 52 is detected as a relative displacement signal y2 indicating a relative displacement value. This relative displacement signal y2
Is input to the coarse movement controller 161 to control the movement of the head 12 by the coarse movement actuator 51.

With such a configuration, coarse movement is performed in two operation modes, that is, a seek operation mode for performing a movement operation between tracks toward a target track, and a following operation mode for causing a head to follow the center of the target track. Head positioning control for positioning the head 12 by cooperation of the actuator 51 and the fine movement actuator 52 is performed.

In the configuration described in the conventional example, since the influence of the frictional force based on the static friction of the coarse actuator is not taken into account in the head positioning control, smooth moving operation becomes difficult, and the servo control is performed accurately. There has been a problem that a situation where no operation is performed occurs.

According to the head positioning apparatus of the present embodiment, it is possible to perform head positioning control with a stable operation even under the influence of the frictional force based on the static friction of the coarse motion actuator, as compared with the conventional example. The operation will be described.
In the present embodiment, the non-linear converter 18 is provided in the coarse movement control unit 161 in order to suppress the influence of the frictional force based on the static friction. The nonlinear converter 18 uses the signal from the phase compensation circuit 610, which is a signal corresponding to the relative displacement signal y2, as the conversion input signal ui, amplifies the conversion input signal ui with a gain depending on the amplitude of the conversion input signal ui, Conversion output signal uo
Has the following nonlinear characteristics. Further, this nonlinear characteristic is such that when the amplitude of the converted input signal ui is small, the converted input signal ui has a larger gain than when the amplitude is large.
Is amplified and converted into a converted output signal uo. More specifically, the detected relative displacement signal y2 has a positive or negative value around a center position Y1 corresponding to a displacement amount of zero, and the converted input signal ui.
Is also a signal having a positive / negative sign, so that the converted input signal ui is amplified with a gain that depends on the absolute value of the amplitude of the converted input signal ui that does not have a positive / negative sign.

The non-linear converter 18 converts such non-linear characteristics.
Therefore, the head positioning apparatus according to the present embodiment performs head positioning control for positioning the head 12 to the target track specified by the target position signal r by the following operation.

Here, in order to explain that the present embodiment operates stably even under the influence of the frictional force based on the static friction of the coarse motion actuator, it can be used in a short distance seek operation in which static friction is a problem. The following description focuses on the operation during the following operation. Further, when the amplitude of the conversion input signal ui is large, the gain equivalent to that of the conventional example is obtained.
When the amplitude of is small, a description will be given on the assumption that a gain higher than that of the conventional example is set in the nonlinear converter 18 in advance.

In the seek operation, when a target track is specified, a difference between the head position signal y indicating the head position Y and the target position signal r is generated. Will be entered. Fine movement control unit 162
Because of the quick response, the fine movement actuator 52 first starts displacing in the target track direction. Fine actuator 5
2 continues the displacement, the displacement amount Y2 of the fine movement actuator 52
Is input to the coarse movement control unit 161 as a relative displacement signal y2. Since the coarse movement control unit 161 has a slow response, the head support mechanism 14 usually starts slowly moving in the target track direction by the coarse movement actuator 51, and the seek operation is started. However, if the static friction of the rotating shaft 140 supporting the head support mechanism 14 is large, a driving force exceeding this static friction force is required at the start of the seek operation.

At this time, if the gain of the amplifier 911 of the coarse movement control section 91 is constant as shown in FIG.
When the head support mechanism 14 is stationary, the coarse movement control signal u1
Will increase. When the increase amount exceeds the static friction force, the head support mechanism 14 starts moving. At the start of the movement, the head support mechanism 14 is rapidly changed because it changes to dynamic friction, and dynamic friction does not require a large driving force as compared with static friction. On the other hand, in the case of a seek operation or a following operation in a short distance, the displacement Y2 of the fine movement actuator 52 does not become so large. For this reason, when the static friction is large, the coarse movement control signal u1 does not increase to a driving force exceeding the static friction force, and the head support mechanism 14 continues to be stationary. In such a state, the fine movement actuator 52 moves to the oscillating state where the displacement in the direction of the target track and the displacement in the direction of zero displacement due to the decrease of the position error signal e2 as a result, or to an unintended position. There were inconveniences such as being displaced.

In this embodiment, the conventional coarse movement controller 9
The non-linear converter 18 is provided in the coarse movement control unit 161 for the amplifier 911 having a constant gain of 1. The non-linear converter 18 uses the signal from the phase compensation circuit 610, which is a signal corresponding to the relative displacement signal y2, as the conversion input signal ui. Is set to be large. By the way, in the configuration of the dual actuator of the present embodiment, after the seek operation is completed, the head positioning control is performed so that the displacement Y2 of the fine movement actuator 52 is always zero. That is, at the start of the next seek operation, the seek operation is started at a minute amplitude of the relative displacement signal y2 which is always close to zero. Therefore, when the seek operation is started, a signal from the phase compensation circuit 610, which is a signal corresponding to the relative displacement signal y2 having the small amplitude, that is, the converted input signal ui.
Is input to the nonlinear converter 18. Conversion input signal ui
Is a very small amplitude, and is amplified by the nonlinear converter 18 with a larger gain than in the conventional example. In other words, at the start of the seek operation, coarse movement actuator 51 is driven with a larger driving force than in the conventional example. As described above, since the coarse motion control unit 161 drives the coarse motion actuator 51 with a larger driving force than the conventional example,
The influence of static friction can be suppressed, and head positioning control can be performed with stable operation. After overcoming the static friction force, a state of dynamic friction occurs, and a large driving force is not required as compared with the start of the seek operation. Further, in the case of a long-distance seek operation, after the start of the seek operation, the displacement amount Y2 of the fine movement actuator 52 becomes sufficiently large, and the gain of the nonlinear converter 18 becomes equal to the gain of the conventional example. At this time, since it is in dynamic friction, it operates stably without requiring a large driving force.

In the case of the following operation, the relative displacement signal y
In the present embodiment, since the non-linear converter 18 is provided in the coarse motion control unit 161 because the amplitude is small, compared to the conventional example using an amplifier having a constant gain in the coarse motion control unit. , The gain increases. Therefore, the coarse movement control unit 16
1 is similar to that at the start of the seek operation,
The coarse movement actuator 51 can be driven with a larger driving force. Therefore, the influence of static friction can be suppressed, and head positioning control can be performed with stable operation. Further, since the gain of the servo control system is larger than that of the conventional example, a higher-speed following operation can be performed.

Generally, when the gain of the servo control system is increased, the speed of the following operation is increased, but at the same time, the phase margin of the servo control system is reduced. As a result, the system becomes oscillating, becomes unstable, is susceptible to disturbances, and its stability against disturbances decreases. For this reason, it is usually necessary to keep the gain of the coarse motion control unit low to some extent, to suppress the servo control system from becoming vibratory, and to stabilize it. Has limitations. On the other hand, in the present embodiment, on the other hand, when the converted input signal ui has a small amplitude, the gain is increased as compared with the conventional example. However, since the gain is large, it is limited to a range where the converted input signal ui has a very small amplitude, so that sufficient stability is maintained. For example, when an impact is applied from the outside, the fine movement actuator 52 and the coarse movement actuator 51 largely deviate from the track position being followed. At this time, the relative displacement signal y2 also increases to draw the target position, and the gain becomes equivalent to that of the conventional example, so that the pulling operation almost similar to that of the conventional example can be performed. As described above, the gain characteristic of the non-linear converter 18 secures almost the same stability as the conventional one.

As described above, when the head support mechanism is driven by the coarse motion actuator, static friction is generated on the rotating shaft. If the static friction is large, smooth moving operation becomes difficult, and the servo control may not be accurately performed. Could occur. In the present embodiment, the fact that the relative displacement signal y2 from the fine movement actuator 52 is very small at the start of the seek operation or the following operation in which the static friction occurs is utilized. Since the non-linear converter 18 is set so that the gain becomes larger when the amplitude of the conversion input signal ui is smaller than when the amplitude is larger, when the static friction occurs such that the relative displacement signal y2 is minute, The gain of coarse movement control section 161 increases. Therefore, when the static friction occurs, it becomes possible to apply a larger driving force to the coarse actuator than in the conventional example. As a result, the head positioning control can be performed with a stable operation even under the influence of the frictional force based on the static friction of the coarse actuator. When the amplitude of the conversion input signal ui is large, the nonlinear converter 18 sets a gain equivalent to that of the conventional example. By having it, stability is secured. Furthermore, since the effect of static friction is suppressed by using the non-linear characteristic, switching can be performed easily and easily without using a detection circuit or switching circuit that detects and controls the state of the head acceleration and other conditions. It is also possible to realize without influence of time or influence of circuit delay time.

FIG. 3 is an example of a block diagram showing a specific configuration of the nonlinear converter 18 and an input / output characteristic diagram thereof. 3A is a block diagram, FIG. 3B is an input / output characteristic diagram, and FIG. 3C is another input / output characteristic diagram.

In FIG. 3A, the level determination circuit 8
11 to detect the amplitude level of the conversion input signal ui,
A gain value is selected from a plurality of predetermined gain values preset in the gain setting unit 812 according to the amplitude level detected by the level determination circuit 811. The gain value is
When the amplitude of the converted input signal ui is small, the gain value is set to be larger than when the amplitude is large. A gain value signal corresponding to the gain value is sent to the variable amplifier 810, and the converted input signal ui is amplified by a gain corresponding to the gain value to output a converted output signal uo.

FIG. 3B is an example of an input / output characteristic diagram showing the relationship between the converted input signal ui and the converted output signal uo. Since the gain corresponds to the slope of the input / output characteristics, in the example of FIG. 3B, the converted input signal ui is compared with the case where the amplitude of the converted input signal ui is equal to or greater than the amplitude level un.
Is a non-linear characteristic in which the converted input signal ui is amplified with a large gain when the amplitude is equal to or less than the amplitude level un. Strictly speaking, the nonlinear converter 18 uses the amplitude level un where the level of the conversion input signal ui is un and −un as a boundary point, and at this boundary point, the conversion input signal ui.
Has a non-linear characteristic that the converted input signal ui is amplified with a larger gain when the amplitude of the converted input signal ui is smaller than when the amplitude of the converted input signal ui is smaller. At the start of the seek operation or during the following operation, the signal from the phase compensation circuit 610, which is a signal corresponding to the relative displacement signal y2, that is, the converted input signal ui is lower than the amplitude level un. For this reason, if the gain at the amplitude level un or more is equal to the gain of the conventional example, the gain becomes larger at the start of the seek operation or at the time of the following operation than at the conventional example, and the static friction is smaller than at the conventional example. The coarse movement actuator 51 is driven with a large driving force, and the influence of static friction can be suppressed. However, during an intermediate seek operation, the converted input signal ui has a gain equal to or higher than the amplitude level un, and thus has a gain equivalent to that of the conventional example, and performs substantially the same operation as the conventional example.

FIG. 3C shows another example of the input / output characteristics. Here, the gain is divided into three stages. This example also has a nonlinear characteristic in which the converted input signal ui is amplified with a larger gain when the amplitude of the converted input signal ui is smaller than when the amplitude of the converted input signal ui is larger.
Due to this characteristic, similarly to the case of FIG. 3B, the influence of the static friction can be suppressed. Although the gain is divided into three stages, it is possible to control more precisely by further dividing the stage.

FIG. 4 is an example of a block diagram showing another specific configuration of the nonlinear converter 18 and an input / output characteristic diagram thereof. 4A shows a block diagram, and FIG. 4B shows an input / output characteristic diagram.

In FIG. 4A, the level conversion circuit 8
21 converts the converted input signal ui into a signal proportional to the amplitude level. The converted signal is supplied to the variable attenuator 8
20 and a variable attenuator 820
Is changed so that the amount of attenuation is reduced when the converted signal is small, and the converted input signal ui is attenuated.
The signal is amplified by the amplifier 822 with a predetermined gain, and the converted output signal uo is output.

FIG. 4B is an input / output characteristic diagram showing the relationship between the converted input signal ui and the converted output signal uo. The configuration of FIG. 4A has a non-linear characteristic in which the converted input signal ui is amplified with a larger gain when the amplitude of the converted input signal ui is smaller than when the amplitude of the converted input signal ui is larger. At the start of the seek operation or during the following operation, a signal from the phase compensation circuit 610, which is a signal corresponding to the relative displacement signal y2, that is, the converted input signal u
i is small. For this reason, if the gain when the amplitude is large is substantially equal to the gain of the conventional example, the gain becomes larger than that of the conventional example at the start of the seek operation or during the following operation, and the static friction is larger than that of the conventional example. The coarse motion actuator is driven by the driving force, and the influence of static friction can be suppressed. However, in the middle of seek operation,
Since the converted input signal ui has a large amplitude, it has a gain equivalent to that of the conventional example, and performs almost the same operation as the conventional example.
Further, the gain continuously increases as the amplitude of the converted input signal ui decreases. Therefore, as compared with the configuration shown in FIG. 3 and a method requiring a switching operation, smooth control can be performed during the entire period of the positioning operation without a sudden state change due to gain switching.

The non-linear converter 18 is similar to that shown in FIGS.
It is feasible other than explained above. For example, a configuration utilizing nonlinear characteristics of a semiconductor is also possible.

As described above, in this embodiment, the control unit 16 controls the displacement of the fine movement actuator based on the position error which is the distance between the target position for positioning the head at the target position and the current position of the head. And detects a value corresponding to the amount of displacement of the fine movement actuator as a relative displacement value.When the absolute value of the relative displacement value is small, the relative displacement value is increased with a larger gain than when the absolute value of the relative displacement value is large. The head has a head positioning control function of controlling the movement of the head by the coarse actuator based on the result of the nonlinear conversion of the corresponding value and the nonlinear conversion, whereby the frictional force based on the static friction of the coarse actuator is Even if it is affected, head positioning control can be performed with a stable operation.

(Second Embodiment) FIG. 5 is a block diagram showing a configuration of a servo control system for controlling a double actuator of a head positioning device according to a second embodiment of the present invention. Since the mechanical configuration of the disk device is the same as that of the first embodiment, the mechanical description of the disk device is omitted here. The same components as those in the first embodiment are denoted by the same reference numerals as those in FIG. In FIG. 5, only the internal configuration of the coarse motion control unit 261 of the control unit 26 is different from that of FIG. The operation principle is the same as that of the first embodiment.

Hereinafter, a description will be given of a portion different from the first embodiment, and an operation capable of suppressing the influence of the static friction in the second embodiment as in the first embodiment. In the present embodiment, the non-linear converter 28 is provided in the coarse movement control unit 261 in order to suppress the influence of the static friction as in the first embodiment. The nonlinear converter 28 uses the relative displacement signal y2 indicating the relative displacement value as the converted input signal ui, amplifies the converted input signal ui with a gain depending on the amplitude of the converted input signal ui, and sets the converted output signal uu as the non-linear characteristic. have. Further, this non-linear characteristic is such that when the amplitude of the converted input signal ui, which is the relative displacement signal y2, is small, the converted input signal ui is amplified with a larger gain than when the converted input signal ui is large, and converted to the converted output signal uu. It is characterized by having. Conversion output signal u
o is phase-compensated to predetermined frequency characteristics and phase characteristics by a phase compensation circuit 612, amplified by a predetermined gain by an amplifier 613, and controls the coarse motion actuator 51 as a coarse motion control signal u1 from the coarse motion control unit 261. I do.

In the present embodiment, the nonlinear converter 28 is provided before the phase compensation circuit 612 as compared with the first embodiment. That is, the order of the phase compensation circuit and the nonlinear converter is opposite to that of FIG.
According to the displacement amount Y2, when the displacement amount Y2 is large, the coarse movement control signal u1 is the same as the conventional example, and when the displacement amount Y2 is small, the coarse movement control signal u1 becomes larger than the conventional example. Thus, the present embodiment is the same as the first embodiment. Therefore, the present embodiment performs almost the same operation as the first embodiment, and has the same effect.

Thus, in the present embodiment, at the start of the seek operation or at the time of the following operation, the coarse actuator 5 has a larger driving force than the conventional example against static friction.
1 to suppress the influence of static friction. But,
At the middle of the seek operation, etc., almost the same operation as in the conventional example is performed. In addition, since the influence of static friction is suppressed by using the non-linear characteristic, it is possible to simply realize without using a state detection circuit or a switching circuit.

Further, since the fine movement actuator 52 itself has nonlinear characteristics, the fine movement actuator 52 itself may correct the displacement amount and the detection signal in proportion to a circuit having inverse nonlinear characteristics. In such a case, it is possible to reduce the number of circuit elements by having the inverse nonlinear characteristic also in the nonlinear converter 28.

As described above, in the present embodiment, the control unit 26 controls the displacement of the fine movement actuator based on the position error which is the distance between the target position for positioning the head at the target position and the current position of the head. And detects a value corresponding to the amount of displacement of the fine movement actuator as a relative displacement value. Non-linear conversion, based on the result of the non-linear conversion,
It has a head positioning control function that controls the movement of the head by the coarse motion actuator, thereby enabling head positioning control with stable operation even under the influence of the frictional force based on the static friction of the coarse motion actuator. .

(Third Embodiment) FIG. 6 is a configuration diagram showing a configuration of a head positioning device according to a third embodiment of the present invention. Since the mechanical configuration of the disk device is the same as that of the first embodiment, the mechanical description of the disk device is omitted here. The same components as those in the first embodiment are denoted by the same reference numerals as those in FIG. This embodiment is different from the first embodiment described with reference to FIG. 1 in that the control unit is performed by digital signal processing.

In FIG. 6, the double actuator according to the present embodiment has a control unit 3 composed of a digital control circuit.
The coarse movement control data u1 and the fine movement control data u2 of FIG.
The A / D converter 65 and the D / A converter 66 convert digital data into an analog signal, and are driven and positioned based on the drive signals converted by the drive circuits 63 and 64. The controller 36 controls relative displacement data y2 indicating a relative displacement value obtained by converting a signal corresponding to the displacement Y2 of the fine movement actuator 52 from an analog signal to digital data by the AD converter 67, and a position from the servo signal read from the head 12. Control data is generated based on the data y and target position data r instructed to perform a required positioning operation, and the coarse actuator 51 and the fine actuator 5 are driven by a drive signal based on the derived control data.
2 servo control is performed.

In the control unit 36, the head position data y indicating the current position and the target position data r are subtracted by a subtractor 395 realized by a subtraction circuit, and the difference resulting from the subtraction is used as position error data e2 indicating a position error. Is output. The fine movement control section 362 receives the position error data e2 and controls the fine movement actuator 52.
2, a predetermined phase and frequency characteristic and a multiplier 623 set a gain that is a predetermined amplification factor. The phase compensation circuit 622 can be realized by a digital filter including an adder / subtracter, a delay element, and a multiplication circuit. The multiplier 623 can also be realized as a multiplication circuit using a combination of an adder and a bit shift circuit, or a conversion table using a memory storing the multiplication result. In addition,
Although the cascade connection from the phase compensation circuit 622 to the multiplier 623 has been described, the reverse is also true, and the multiplication function is also provided.
2, any configuration may be used as long as the predetermined phase and frequency characteristics and gain for driving the fine movement actuator 52 can be set. The coarse movement control unit 361 receives the relative displacement data y2 and controls the coarse movement actuator 51. Therefore, a predetermined phase and frequency characteristic are set in the phase compensation circuit 612 and a predetermined gain is set in the nonlinear conversion table 38. I have. In the present embodiment, the non-linear conversion table 38 functions as a non-linear converter having non-linear characteristics. The non-linear conversion table 38 is realized by a memory that stores the result of multiplying the conversion input data ui by a multiplier corresponding to the absolute value of the conversion input data ui. The non-linear conversion table 38 uses the data from the phase compensation circuit 612, which is data corresponding to the relative displacement data y2, as the conversion input data ui. Is stored as a result of multiplication of the conversion input data ui by a large multiplier. This multiplier corresponds to the gain of the servo control system for the coarse actuator.

With such a configuration, the coarse movement actuator 51 is provided for two operation modes, that is, a seek operation mode for moving between tracks toward the target track and a following operation mode for following the head to the center of the target track. The head positioning control for positioning the head 12 is performed by the cooperation of the actuator and the fine movement actuator 52. In this embodiment, since the servo control system is digitally processed, the configuration is different from that of the first embodiment, but the same operation is performed. That is,
The operation principle is the same as that described for the servo control system model in FIG. 2, and the same effect can be obtained. Furthermore, since the nonlinear conversion table 38 only needs to store desired data in a memory, desired characteristics can be obtained more accurately, flexibly, and easily as compared with analog means. For this reason, a more stable positioning operation can be performed as compared with the first and second embodiments.

FIG. 7 is an example of a block diagram showing a specific configuration of the nonlinear conversion table 38 and an input / output characteristic diagram thereof. 7A is a block diagram, and FIG. 7B is an input / output characteristic diagram. In FIG. 7A, a desired output value for the converted input data ui is stored as data at an address corresponding to the data value of the converted input data ui in the memory 381 as a storage element. When ui is input, desired conversion output data uo is output.

FIG. 7B is an example of an input / output characteristic diagram showing the relationship between the converted input signal ui and the converted output signal uo. In the configuration of FIG. 7A, the conversion input data ui
Is smaller, the conversion input data u is larger by a multiplier than when the absolute value of the conversion input data ui is larger.
i is a non-linear characteristic having a multiplied characteristic. In particular, the characteristic shown in FIG. 7B is set so that the conversion input data ui whose absolute value is equal to or greater than um is set to correspond to a constant gain equivalent to the conventional example. Conversion input data ui whose absolute value of ui is less than or equal to um
The gain is set so as to correspond to the characteristic that the gain gradually increases as the absolute value of the conversion input data ui decreases. Since the non-linear conversion table 38 has such input / output characteristics, the gain when the absolute value of the conversion input data ui is large is almost the same as the gain in the conventional example. The absolute value of the data from the phase compensation circuit 612, that is, the converted input data ui, which is the data corresponding to the above, is large, and the same operation as the conventional example is performed. However, at the start of the seek operation or at the time of the following operation, the absolute value of the converted input data ui is small, so that a large gain is obtained. Can suppress the effects of In the characteristic curve shown in FIG. 7B, when the absolute value of the converted input data ui is less than the absolute value um, the gain is slightly larger than the conventional example and the absolute value of the converted input data ui decreases. As the gain increases, the gain increases greatly. Since the gain is continuously changed, smoother control can be performed during the entire period of the positioning operation as compared with a method requiring a switching operation.

FIG. 8 is a circuit diagram of the present embodiment described with reference to FIG.
FIG. 9 is a configuration diagram showing another configuration. FIG. 8 is different from FIG. 6 in that the non-linear conversion table 48 and the phase compensation circuit 614 are reversed in the coarse movement controller 461 of the controller 46. That is, the nonlinear conversion processing is first performed by the nonlinear conversion table 48, and the phase compensation circuit 614 then performs the phase compensation calculation processing. However, as described in the second embodiment, also in the present embodiment, the same effects as in FIG. 6 can be obtained as the effects in FIG. Furthermore, since the fine movement actuator 52 itself has nonlinear characteristics, the fine movement actuator 52 may correct the displacement amount and the detection data from the detection signal in a non-linear table having inverse nonlinear characteristics so as to be proportional. In such a case, it is possible to reduce the number of circuit elements by having the inverse nonlinear characteristic also in the nonlinear conversion table 48.

As described above, in this embodiment, the control unit 36 controls the displacement of the fine movement actuator based on the position error which is the distance between the target position for positioning the head at the target position and the current position of the head. And detects a value corresponding to the amount of displacement of the fine movement actuator as a relative displacement value.When the absolute value of the relative displacement value is small, the relative displacement value is increased with a larger gain than when the absolute value of the relative displacement value is large. It has a head positioning control function of nonlinearly converting the corresponding value and controlling the movement of the head by the coarse actuator based on the result of the nonlinear conversion. Further, the control unit 46 controls the displacement of the fine movement actuator based on the position error which is the distance between the target position for positioning the head at the target position and the current position of the head, and adjusts the displacement of the fine movement actuator. The value is detected as a relative displacement value, and when the absolute value of the relative displacement value is small, the relative displacement value is nonlinearly transformed with a larger gain than when the absolute value of the relative displacement value is large, and based on the result of the nonlinear transformation,
It has a head positioning control function for controlling the movement of the head by the coarse actuator. Thus, the head positioning control can be performed with a stable operation even under the influence of the frictional force based on the static friction of the coarse actuator.

(Fourth Embodiment) FIG. 9 is a configuration diagram showing a configuration of a head positioning device according to a fourth embodiment of the present invention. Since the mechanical configuration of the disk device is the same as that of the first embodiment, the mechanical description of the disk device is omitted here. The same components as those in the third embodiment are denoted by the same reference numerals as those in FIG. This embodiment is different from the first embodiment described with reference to FIG. 1 in that the control unit is performed by digital signal processing. The digital signal processing is performed by a microprocessor in FIG.
And the third embodiment described with reference to FIG.

In FIG. 9, the dual actuator according to the present embodiment uses a common bus 564 to control the coarse movement control data u1 and the fine movement control data u2 of the control unit 56 which performs servo control by digital computation by the microprocessor 561.
Are output to the D / A converter 65 and the D / A converter 66, and are converted to analog signals by the D / A converter 65 and the D / A converter 66. Further, the dual actuator is driven by the drive circuit 63 and the drive circuit 64. It is driven and positioned according to the signal. The control unit 56 controls the relative displacement data y2 obtained by converting a signal corresponding to the displacement Y2 of the fine movement actuator 52 into digital data by the AD converter 67, the head position data y from the servo signal read from the head 12, and the required positioning. Target position data r and the like instructed to operate are input via the common bus 564, control data is generated from these data, and the coarse actuator 51 and the fine actuator are driven by drive signals based on the derived control data. The servo control of 52 is performed. A control program 563 for performing servo control is stored in a memory 562 as a machine-readable recording medium as a head positioning control program for executing a head positioning control method, and is sequentially read by a microprocessor 561. And execute servo control. Further, the nonlinear conversion table 58 which is a feature of the present invention is also stored in the memory 562. In the present embodiment, the non-linear conversion table 58 functions to perform a desired non-linear conversion. The nonlinear conversion table 58 may be stored in a memory other than the memory 562.

FIG. 10 is an example of a flowchart showing the procedure of the control program 563 in each step for causing the head positioning control program to function as servo control. In step 200, the control program 563 is called. First, in step 201, head position data y indicating the current position is read from the servo signal. In step 202, the head position data y and the target position data r are subjected to subtraction processing, and the subtraction result is temporarily stored as position error data e2 indicating a position error. In step 203, the position error data e2 is read out, and based on the position error data e2, arithmetic processing for phase compensation is performed with a predetermined phase and frequency characteristic and a gain that is a predetermined amplification factor, and temporarily stored as fine movement control data u2. In step 204, the fine movement control data u2 is output to the DA converter 66. From the DA converter 66, the fine movement control data u2
Is output to the fine movement actuator 52 via the drive circuit 64 as a signal based on that's all,
In steps 201 to 204, a function as fine movement control means is executed to control the fine movement actuator 52.

In step 205, the relative displacement data y 2 indicating the relative displacement value corresponding to the displacement amount Y 2 of the fine movement actuator 52 is read from the AD converter 67. In step 206, the coarse motion actuator 51 is controlled based on the read relative displacement data y2, and a phase compensation calculation process is performed with a predetermined phase and frequency characteristic based on the relative displacement data y2 to obtain coarse motion control data u3. It is temporarily stored and used as conversion input data ui. Step 20
In step 7, the result of multiplying the conversion input data ui temporarily stored as the coarse movement control data u3 by a multiplier corresponding to the absolute value of the conversion input data ui is input to the nonlinear conversion table 58 of the memory 562 storing the result. Is read as converted output data uo. Here, the nonlinear conversion table 5
8 is the coarse movement control data u3 which is data corresponding to the relative displacement data y2, that is, the conversion input data ui has a larger multiplier when the absolute value of the conversion input data ui is small than when the absolute value is large. The multiplied data is stored, and this data is used as converted output data uo. This multiplier corresponds to the gain of the servo control system to the coarse actuator. In step 207, a function as a non-linear conversion means is executed. Step 208
Then, the conversion output data uo is output to the DA converter 65 as the coarse movement control data u1. A coarse drive signal is output from the DA converter 65 to the coarse actuator 51 via the drive circuit 63 as a signal based on the coarse control data u1. As described above, Step 205, Step 206,
In step 208, a function as a coarse movement driving means is executed to control the coarse movement actuator 51.

FIG. 11 is an example of a flowchart showing another procedure of each step of the control program 563 for functioning as servo control. The difference is that step 206 and step 207 in FIG. 10 are reversed. That is, in FIG. 11, a nonlinear conversion process is first performed in step 216, and a phase compensation calculation process is performed in step 217. However, as described in the second embodiment, similar effects can be obtained as the effects in FIGS.

In the flowchart of FIG. 10 or FIG. 11, at step 209, the process returns to the main program. The main program is a program that controls the entire disk device. As for servo control, seek control and following control are monitored by a main program. Returning to the main program at step 209,
The main program determines whether the target position R has been reached. For example, when the vehicle does not reach the target position R, FIG.
The seek control and the following control are performed as appropriate by repeating the processing shown in FIG.

With such a configuration, coarse movement is performed in two operation modes, that is, a seek operation mode for performing a movement operation between tracks toward a target track, and a following operation mode for causing a head to follow the center of the target track. Head positioning control for positioning the head 12 is performed by cooperation between the actuator 51 and the fine movement actuator 52. In this embodiment, since the servo control system is digitally processed by the microprocessor 561,
Although the configuration is different from the first embodiment to the third embodiment, the same operation is performed. That is, the operation principle is the same as that described in the servo control system model of FIG. 2 or FIG. 5, and the same effect is obtained. In addition, as the nonlinear conversion table 58, FIG.
Since the same configuration as the nonlinear conversion table 38 described in (1) can be used and desired data can be stored in the memory, desired characteristics can be obtained more accurately, flexibly, and easily.

In step 207 of FIG. 10 or step 216 of FIG.
Although the example in which the non-linear conversion is performed using FIG. 8 has been described, the non-linear conversion having similar characteristics may be performed by arithmetic processing.

The fine movement actuator 52 has nonlinear characteristics because the fine movement actuator 52 itself has nonlinear characteristics.
In some cases, correction is performed so that the amount of displacement is proportional to the detection signal in a circuit having inverse nonlinear characteristics. In such a case, it is possible to reduce the number of storage elements or their storage areas by making the nonlinear conversion table 58 have characteristics that also have the inverse nonlinear characteristics. Further, it can be easily combined with hysteresis correction and temperature correction characteristics.

Also, it has been described that the control program 563 as the head positioning control program is stored in the memory 562 as a machine-readable recording medium. Specifically, the control program 563 may be recorded in a read-only ROM in advance, or may be recorded in a storage medium other than the semiconductor memory in advance,
When using the head positioning device, the head positioning device may be used by writing to a writable / readable RAM. Further, the microprocessor and the memory may be integrated, and the control program 563 may be stored in this memory.
In the storage medium on which the control program 563 is recorded, a program other than the control program 563 may be recorded in another area. Such changes do not affect the effects of the present invention.

As described above, in the present embodiment, the control unit 56 controls the displacement of the fine actuator based on the position error which is the distance between the target position for positioning the head at the target position and the current position of the head. Is controlled, and a value corresponding to the amount of displacement of the fine movement actuator is detected as a relative displacement value. Alternatively, the head positioning control program has a head positioning control function of controlling the movement of the head by the coarse actuator based on the result of the nonlinear conversion of the value corresponding to the relative displacement value and the result of the nonlinear conversion. The head positioning control can be performed with a stable operation even under the influence of the frictional force based on the static friction of the coarse actuator.

(Fifth Embodiment) FIG. 12 is a configuration diagram showing a configuration of a magnetic disk drive according to a fifth embodiment of the present invention. In FIG. 12, a magnetic head 12 (hereinafter, referred to as a head) for recording and reproducing information on a magnetic disk 11 (hereinafter, referred to as a disk), which is one of disk-shaped recording media rotated by a spindle 17, has a head slider 13. It is formed integrally with the tip. The head slider 13 is mounted on the tip of a fine movement actuator 52, and the fine movement actuator 52 is
4 is connected to the tip. The head support mechanism 14
The head 12 is driven by a coarse movement actuator 51 about a rotation axis 140 of the magnetic disk apparatus main body and cooperates with a fine movement actuator 52 to position the head 12. The coarse movement actuator 51, the fine movement actuator 52, and the head support mechanism 14 together form a positioning mechanism 15. Thus, the positioning mechanism 15 of the present embodiment
Are a coarse actuator 51 and a fine actuator 52
And a dual actuator configuration. The coarse movement actuator 51 moves the head 12 at the distal end by rotating the head support mechanism 14 by a voice coil motor or the like, and is mainly used for large movements such as a seek operation and a plurality of track jumps. On the other hand, the fine movement actuator 52 moves the head 12 at the distal end by performing a wide-range position control with a narrow movable range due to a displacement of a piezo element or the like, and is mainly used for high-speed fine positioning such as track following and one-track jump. Is done.

The positioning mechanism 15 is driven and positioned according to a control signal from the control section 6 constituted by a control circuit. The control unit 6 controls the relative displacement signal y2 corresponding to the displacement amount of the fine movement actuator 52, the head position signal y included in the servo information read from the head 12, the target position information instructed to perform a required positioning operation, and the like. Generate signals or control data. The control signal or control data is converted into drive signals d1 and d2 by a drive circuit, and the coarse actuator and the fine actuator are driven to perform servo control of both actuators.

The control unit 6 is the same as the control unit 1 of FIG. 1 described in the first to fourth embodiments of the present invention.
6, the control unit 26 in FIG. 5, the control unit 36 in FIG. 6, the control unit 46 in FIG. 8, or the control unit 56 in FIG. 9 can be used. As a result, a magnetic disk drive capable of performing head positioning control with stable operation even under the influence of frictional force based on the static friction of the coarse actuator can be realized.

In the first to fifth embodiments, the input signal or input data of the coarse movement control unit will be described as a signal or data based on a detection signal for detecting the amount of displacement of the fine movement actuator. However, a signal or data generated by an estimator that models a fine movement actuator may be used, and the same effect can be obtained.

In the first to fifth embodiments, the magnetic disk device has been described as an example. However, the present invention is not limited to this. For example, an optical head is mounted on a head slider. The present invention can also be applied to an optical disk device having the following configuration.

[0109]

As described above, the present invention adds a function as a non-linear converter, non-linear deformation table, or non-linear conversion means for performing the above-described non-linear conversion to the servo control system of the conventional dual actuator. ing. By utilizing the fact that the relative displacement signal corresponding to the displacement amount of the fine motion actuator or the relative displacement value of the relative displacement data is small at the start of a seek operation or a following operation in which static friction occurs in the coarse motion actuator, When the absolute value of the relative displacement value is small, the non-linear converter, the non-linear deformation table, or the non-linear conversion means that performs the non-linear conversion
Since the gain is set to be larger than when the absolute value of the relative displacement value is large, the gain for servo-controlling the coarse motion actuator is large when static friction occurs, such as when the relative displacement value is minute. Become. Therefore, when static friction is generated, it becomes possible to apply a larger driving force to the coarse motion actuator than in the past. As a result, the head positioning control can be performed with a stable operation even under the influence of the frictional force based on the static friction of the coarse actuator. Therefore, when the head positioning device of the present invention is applied to a storage device such as a magnetic disk device, an excellent effect that the head positioning control can be performed with a stable operation even under the influence of the frictional force based on the static friction of the coarse actuator. Can be provided.

Further, in the present invention, a step of performing the above-described non-linear conversion is added to the conventional servo control method for a double actuator. By using the fact that the relative displacement data from the fine actuator is minute at the start of the seek operation or the following operation in which the static friction occurs in the coarse actuator, the step of performing the nonlinear conversion corresponds to the relative displacement data. When the absolute value of the conversion input data is small, the gain is set to be larger than when the absolute value of the conversion input data is large, so when static friction occurs, such as when the relative displacement data is minute, As a result, the gain for servo-controlling the coarse actuator becomes large. Therefore, when static friction is generated, it becomes possible to apply a larger driving force to the coarse motion actuator than in the past. As a result, the head positioning control can be performed with a stable operation even under the influence of the frictional force based on the static friction of the coarse actuator. Therefore, if the head positioning control method of the present invention is applied to a storage device such as a magnetic disk device, the head positioning control can be performed with stable operation even under the influence of the frictional force based on the static friction of the coarse actuator. It is possible to provide a head positioning control method having an effect.

Further, according to the present invention, a step of performing the above-described nonlinear conversion is added to a conventional servo control program for a dual actuator, and a program functioning as a nonlinear conversion unit is added. By using the fact that the relative displacement data corresponding to the displacement amount of the fine motion actuator is minute at the start of the seek operation or the following operation in which the static friction occurs in the coarse motion actuator,
The nonlinear characteristic in the step of performing the nonlinear conversion or in the program functioning as the nonlinear conversion means is that when the absolute value of the conversion input data corresponding to the relative displacement data is small, the gain is larger than when the absolute value of the conversion input data is large. Since the setting is made to be large, the gain for servo-controlling the coarse actuator becomes large when static friction occurs, such as when the relative displacement data is minute. Therefore, when static friction is generated, it becomes possible to apply a larger driving force to the coarse motion actuator than in the past. As a result, the head positioning control can be performed with a stable operation even under the influence of the frictional force based on the static friction of the coarse actuator. Therefore, if the head positioning control method of the present invention is applied to a storage device such as a magnetic disk device, the head positioning control can be performed with stable operation even under the influence of the frictional force based on the static friction of the coarse actuator. A head positioning control program having an effect can be provided.

The present invention also provides a conventional servo control program for a dual actuator in which a step for performing the above-described nonlinear conversion is added, and a machine which has a head positioning control program in which a program functioning as a nonlinear conversion means is added. It is a readable recording medium.
By reading the head positioning control program from the recording medium and executing the head positioning control program, the relative motion corresponding to the displacement of the fine actuator can be obtained at the start of a seek operation or a following operation in which static friction occurs in the coarse actuator. The step of performing non-linear conversion using the small displacement data and the non-linear characteristics of the program functioning as the non-linear conversion means are performed when the absolute value of the conversion input data corresponding to the relative displacement data is small. Since the gain is set to be larger than when the absolute value of is large, the gain for servo-controlling the coarse actuator becomes large when static friction occurs such that the relative displacement data is minute. Therefore, when static friction is generated, it becomes possible to apply a larger driving force to the coarse motion actuator than in the past. As a result, the head positioning control can be performed with a stable operation even under the influence of the frictional force based on the static friction of the coarse actuator. Therefore, if the recording medium on which the head positioning control program of the present invention is recorded is applied to a storage device such as a magnetic disk device, the head positioning can be performed in a stable operation even under the influence of the frictional force based on the static friction of the coarse actuator. It is possible to provide a head positioning device having an excellent effect that control can be performed.

Further, the present invention uses the head positioning device, the head positioning control method, the head positioning control program, or a recording medium on which the head positioning control program is recorded for the head positioning control, thereby obtaining the static friction of the coarse actuator. A disk device having an excellent effect that head positioning control can be performed with a stable operation even under the influence of frictional force based on the above.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a configuration of a head positioning device according to a first embodiment of the present invention;

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

FIG. 3A is a block diagram showing the configuration of a specific example of the nonlinear converter according to the first embodiment of the present invention. FIG. 3B is the input / output characteristic diagram.

FIG. 4A is a block diagram showing the configuration of another specific example of the nonlinear converter according to the first embodiment of the present invention;

FIG. 5 is a block diagram showing a configuration of a servo control system according to a second embodiment of the present invention.

FIG. 6 is a configuration diagram showing a configuration of a head positioning device according to a third embodiment of the present invention.

FIG. 7A is a block diagram showing the configuration of a specific example of a nonlinear conversion table according to the third embodiment of the present invention; FIG.

FIG. 8 is a configuration diagram showing another configuration of the head positioning device according to the third embodiment of the present invention.

FIG. 9 is a configuration diagram showing a configuration of a head positioning device according to a fourth embodiment of the present invention.

FIG. 10 is a flowchart showing a procedure of a head positioning control program according to a fourth embodiment of the present invention.

FIG. 11 is a flowchart showing another procedure of a head positioning control program according to the fourth embodiment of the present invention.

FIG. 12 is a configuration diagram showing a configuration of a magnetic disk drive according to a fifth embodiment of the present invention;

FIG. 13 is a configuration diagram showing a configuration of a conventional head positioning device.

[Explanation of symbols]

6, 16, 26, 36, 46, 56, 96 Control unit 11 Magnetic disk 12 Magnetic head 13 Head slider 14 Head support mechanism 15 Positioning mechanism 17 Spindle 18, 28 Non-linear converter 38, 48, 58 Non-linear conversion table 51 Coarse movement Actuator 52 Fine motion actuator 63, 64 Drive circuit 65, 66 DA converter 67 AD converter 91, 161, 261, 361, 461 Coarse motion control unit 92, 162, 362 Fine motion control unit 94 Adder 95, 395 Subtractor 140 Rotation Axis 381 Memory 561 Microprocessor 562 Memory 563 Control program 564 Common bus 610,612,614,620,622,910,9
Reference Signs List 20 phase compensation circuit 613, 621, 822, 911, 921 amplifier 623 multiplier 810 variable amplifier 811 level determination circuit 812 gain setting section 820 variable attenuator 821 level conversion circuit

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) G11B 21/21 G11B 21/21 CF term (Reference) 5D042 LA01 MA15 5D059 AA01 BA01 CA08 CA30 DA19 EA08 5D096 NN03 NN07 RR01 RR09 5H303 AA22 BB02 BB18 CC03 CC07 DD01 DD14 EE03 FF07 FF08 KK24 LL01 LL02

Claims (15)

[Claims] 1. A head for performing recording and reproduction of information on a disk-shaped recording medium, a fine actuator for finely positioning the head, and a head support mechanism on which the fine actuator is mounted are moved to move the head. A coarse movement actuator for performing coarse positioning; and a control unit for controlling displacement of the fine movement actuator and movement of the head by the coarse movement actuator, wherein the control unit is configured to position the head at a target position. Controlling the displacement of the fine movement actuator based on a position error that is a distance between the target position and the current position of the head; detecting a value corresponding to the displacement amount of the fine movement actuator as a relative displacement value; When the absolute value of the value is small, compared to when the absolute value of the relative displacement value is large. A head positioning control function for non-linearly converting the relative displacement value with a large gain and controlling the movement of the head by the coarse actuator based on the result of the non-linear conversion. 2. The control section calculates a difference between a target position signal for positioning the head at the target position and a head position signal from servo information on the recording medium reproduced by the head. And a fine movement control unit for controlling the displacement of the fine movement actuator based on the position error signal; and inputting a relative displacement signal corresponding to the displacement amount of the fine movement actuator, and moving the head by the coarse movement actuator. A coarse movement control unit for controlling the relative displacement signal as a conversion input signal, when the amplitude of the conversion input signal is small, as compared with when the amplitude of the conversion input signal is large. A non-linear converter having a non-linear characteristic in which a result obtained by amplifying the conversion input signal with a large gain is used as a conversion output signal; Based on the head positioning apparatus as claimed in claim 1, wherein the controlling the movement of the head by the coarse actuator. 3. The control section calculates a difference between target position data for positioning the head at the target position and head position data from servo information on the recording medium reproduced by the head from position error data. And enter
A fine movement control unit that controls the displacement of the fine movement actuator based on the position error data; and a coarse movement control unit that inputs relative displacement data corresponding to a displacement amount of the fine movement actuator and controls movement of the head by the coarse movement actuator. A motion control unit, wherein the coarse motion control unit uses the relative displacement data as conversion input data, and a larger multiplier when the absolute value of the conversion input data is smaller than when the absolute value of the conversion input data is larger. And a non-linear converter having a non-linear characteristic in which a result of the multiplication multiplied by the conversion input data is used as conversion output data. The movement of the head by the coarse actuator is controlled based on the conversion output data. 2. The head positioning device according to claim 1, wherein 4. The control unit comprises: a microprocessor capable of controlling the fine actuator and the coarse actuator; a memory storing a program for operating the microprocessor; and a controller for operating the microprocessor. The head positioning apparatus according to claim 1, further comprising a program, wherein the program has a head positioning control program that realizes the head positioning control function by reading and executing the program by the microprocessor. . 5. The head positioning control program according to claim 1,
The microprocessor, as a position error data, a difference between target position data for positioning the head at the target position and head position data from servo information on the recording medium reproduced by the head. Fine movement control data for controlling the displacement of the fine movement actuator based on the data, fine movement control means for driving the fine movement actuator based on the fine movement control data; As the displacement data, the relative displacement data is used as the conversion input data, and when the absolute value of the conversion input data is small, the conversion input data is multiplied by a larger multiplier than when the absolute value of the conversion input data is large. Non-linear transformation with nonlinear characteristics using the result of multiplication as conversion output data Means, based on the converted output data, derives coarse movement control data for controlling movement of the head by the coarse movement actuator, and coarse movement control means for driving the coarse movement actuator based on the coarse movement control data; 5. The head positioning apparatus according to claim 4, wherein the head positioning control program is a program for causing the computer to function as a head. 6. The head positioning control program according to claim 1,
The microprocessor, as a position error data, a difference between target position data for positioning the head at the target position and head position data from servo information on the recording medium reproduced by the head; A step of deriving fine movement control data for controlling the displacement of the fine movement actuator based on the position error data; a step of driving the fine movement actuator based on the fine movement control data; Inputting relative displacement data, and using the relative displacement data as conversion input data, wherein when the absolute value of the conversion input data is small, the conversion input data is a larger multiplier than when the absolute value of the conversion input data is large. Multiplied by the result of the multiplication as converted output data 5. The head according to claim 4, wherein the program is a head positioning control program for executing a step of performing a nonlinear conversion having a linear characteristic and a step of driving the coarse actuator based on the converted output data. Positioning device. 7. A head for performing recording and reproduction of information on a disk-shaped recording medium, a fine actuator for finely positioning the head, and a head support mechanism on which the fine actuator is mounted are moved to move the head. A coarse movement actuator for performing coarse positioning, a program for controlling a head positioning device including a control unit for controlling displacement of the fine movement actuator and movement of the head by the coarse movement actuator, wherein the control unit includes: A difference between target position data for positioning the head at a target position and head position data from servo information on the recording medium reproduced by the head is used as position error data, and based on the position error data, Fine movement control data for controlling the displacement of the fine movement actuator Fine movement control means for driving the fine movement actuator based on the fine movement control data, data corresponding to the displacement amount of the fine movement actuator as relative displacement data, the relative displacement data as conversion input data, and the conversion input When the absolute value of the data is small, a non-linear conversion means having a non-linear characteristic in which the result of the multiplication multiplied by the converted input data with a larger multiplier than the case where the absolute value of the converted input data is large is used as the converted output data A coarse movement control unit that derives coarse movement control data for controlling the movement of the head by the coarse movement actuator based on the converted output data, and drives the coarse movement actuator based on the coarse movement control data. Head positioning control program to function. 8. A head for carrying out recording and reproduction of information on a disk-shaped recording medium, a fine actuator for finely positioning the head, and a head support mechanism on which the fine actuator is mounted are moved to move the head. A coarse movement actuator that performs coarse positioning, a method of controlling a head positioning device including a control unit that controls displacement of the fine movement actuator and movement of the head by the coarse movement actuator, wherein the control unit includes: Setting a difference between target position data for positioning the head at a target position and head position data from servo information on the recording medium reproduced by the head as position error data, based on the position error data; Fine movement control data for controlling the displacement of the fine movement actuator Deriving, driving the fine movement actuator based on the fine movement control data, inputting relative displacement data corresponding to the amount of displacement of the fine movement actuator, using the relative displacement data as conversion input data, When the absolute value of the converted input data is small, the nonlinear result having the nonlinear characteristic that the result of the multiplication multiplied by the converted input data by a larger multiplier is used as the converted output data as compared with when the absolute value of the converted input data is large. Performing a conversion and driving the coarse actuator based on the converted output data. 9. A head positioning control program for executing the head positioning control method according to claim 8. 10. A machine-readable recording medium having an area in which the head positioning control program according to claim 7 is recorded. 11. A head for performing recording and reproduction of information on a disk-shaped recording medium, a fine actuator for finely positioning the head, and a head support mechanism on which the fine actuator is mounted are moved to move the head. A coarse movement actuator that performs coarse positioning; and a control unit that controls displacement of the fine movement actuator and movement of the head by the coarse movement actuator, wherein the control unit can control the fine movement actuator and the coarse movement actuator A microprocessor and input data are input as conversion input data, and when the absolute value of the conversion input data is small, the conversion input data is multiplied by a larger multiplier than when the absolute value of the conversion input data is high. The result of the multiplication is used as converted output data. A non-linear conversion table having a shape characteristic; a memory storing a program for operating the microprocessor; and the program for operating the microprocessor. By reading and executing, the control unit calculates a difference between target position data for positioning the head at a target position and head position data from servo information on the recording medium reproduced by the head from a position error. Fine movement control data for controlling the displacement of the fine movement actuator based on the position error data, and fine movement control means for driving the fine movement actuator based on the fine movement control data; displacement amount of the fine movement actuator Data corresponding to the relative displacement Nonlinear conversion means for converting the relative displacement data into the conversion input data, and converting the result obtained by the non-linear conversion table into conversion output data; and moving the head by the coarse actuator based on the conversion output data. A head positioning control program which derives coarse movement control data for controlling the coarse movement control data and functions as coarse movement control means for driving the coarse movement actuator based on the coarse movement control data. 12. A disk device comprising the head positioning device according to claim 1, 2, 3, 4, 5, 6, and 11. 13. A disk drive using the head positioning control method according to claim 8. 14. A disk drive comprising the head positioning control program according to claim 7. 15. A disk device comprising the recording medium according to claim 10.