JPH0574077A - Head arm driving device - Google Patents

Abstract

PURPOSE:To provide a head arm drive capable of stable positioning control without using an outside attaching ROM, etc., and without being dependent on the position of the arm even when the environmental condition of the outside is changed and positioning control of the arm adapting to the change of the environment after shipping. CONSTITUTION:A disturbance quantity is detected from a signal reproduced through a head 26 by a position signal detecting part 11 and stored in a RAM 12 through a DSP bus, further, a disturbance corrective quantity is calculated by the DSP 13 through the DSP bus. This corrected output signal and an original positioning control output signal are added in the DSP 13 and a torque disturbance corrected signal is outputted to a D/A converter 14 through the DSP bus. A VCM 31 is controlled through the D/A converter 14, an LPF 29 and a VCM driving circuit 30 and a head arm 23 is positioned.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a head arm drive device suitable for application to, for example, a hard disk device which is an external storage device of a computer.

[0002]

2. Description of the Related Art Conventionally, a hard disk device uses a highly responsive actuator such as a voice coil motor in order to perform a high-speed seek operation. This actuator moves the head arm to a target track position on the recording medium. After the movement, the hard disk device writes data in the recording medium or reads data from the recording medium via the head attached to the tip end side of the head arm.

The structure of a conventional hard disk device will be described with reference to the schematic block diagram shown in FIG. In a hard disk device which is an external storage medium, a disk 52 is horizontally mounted and stored in a mounting table 53 in a housing 51 of the above device. The disk 52 is rotated at a high speed in the direction of arrow a by a motor 54. An actuator 57 including a head arm 55 and a voice coil motor 56 is arranged inside the housing 51.
The head arm 55 is horizontally rotatably mounted around a support shaft 58 in the directions of arrows b and b'through a bearing or the like. A head (read head, servo head) 59 is attached to the tip of the head arm 55. The voice coil motor 56 for driving the head arm is composed of a voice coil 60 provided at the rear end of the head arm 55, a fixed yoke fixedly arranged in the housing 51, and a magnetic circuit 61 composed of a permanent magnet.

Between the head arm 55 and the fixed side control circuit portion 62, flexible cables 64 and 65, which are so-called flexible printed boards, are bent and arranged as connecting members. These flexible cables 64,
Reference numeral 65 denotes the flexible printed circuit board which is a strip-shaped thin plate having flexibility, and the one end sides 64a and 65a are connected to the head arm 5
5, and the other ends 64b and 65b are connected and fixed to predetermined positions of the control circuit unit 62. The flexible cable 64 includes the moving head 59 and the fixed side control circuit unit 1.
2 is connected. The flexible cable 65 connects the moving voice coil motor 60 and the fixed side control circuit unit 62. The housing 5
A lid is attached to the upper part of the housing 1,
The whole has a closed structure (not shown).

The above-mentioned hard disk device is a disk 52.
While rotating the head arm 55 at high speed in the direction of arrow a by the motor 54,
Are reciprocally driven in the directions of arrows b and b '. By this drive, the head 59, which is levitated from the recording surface of the disk 52 with a gap of submicron, reciprocates along the radial direction on the recording surface. Recording / reproduction of the disk 52 is performed by the head 59. When recording / reproducing, the flexible cable 64, 6 is used for recording / reproducing signals and servo information signals.
Received via 5 At this time, when the head arm 55 reciprocates, the flexible cables 64 and 65 follow the reciprocating motion of the head arm 55 by bending and extending the bent portions 64c and 65c.

However, the bending of the bent portions 64c and 65c of the flexible cable causes elastic repulsive force, so-called flex stress. This flex stress acts on the positioning control system of the head arm 55 as a torque disturbance. For this reason, it becomes impossible to feed the head 59 to the target track position with high accuracy and at high speed for positioning.

[0007] Therefore, the applicant of the present invention has filed Japanese Patent Application Laid-Open No. 63-
In Japanese Patent No. 275082, a head track position detecting means and a storage section for giving an external force compensation value at the time of positioning corresponding to the track position are provided, and an external force compensation value measured in advance for each track position is stored. At the time of positioning, the external force compensation value corresponding to the track position of the head is read, and the actuator is driven based on that value, which causes disturbances in positioning control, such as the restoring force of the flexible cable and the wind force generated by the spindle motor that affects the head slider. It is possible to perform stable head positioning that is not affected by external disturbances, such as the torque disturbance, which compensates for the external force that changes depending on the position of the head arm and cancels out the access time of the head arm. We have proposed a head positioning control system for disk drives.

Further, the external force compensating circuit adopting the head positioning control system of the above-mentioned disk drive also has a method of storing the external force compensating amount in a ROM table in advance before shipment.

[0009]

However, in actual hard disk devices, the offset voltage of the voice coil motor driver differs from device to device. Therefore, in the external force compensating circuit described above, the external force compensating amount of each device is measured and stored in the ROM table before shipment and the external R compensator.
OM becomes necessary.

Further, even if external force compensation is performed before shipment, it may happen that the compensation amount stored in the ROM cannot cope with environmental changes such as temperature changes after shipment.

Therefore, in view of the above-mentioned circumstances, the present invention, even without using an external ROM or the like, of an external force that changes depending on the individual electric influence of the apparatus or the position of the head arm, which is so-called torque disturbance. It is an object of the present invention to provide a head arm drive device that can cancel the influence and can cope with a change in environment.

[0012]

A head arm drive device according to the present invention is a head arm drive device for controlling the positioning of a head, and the disturbance amount at at least two or more different circumferential track positions on a recording medium. Detecting means for detecting the signal, storage means for storing an output signal from the detecting means, calculating means for calculating a disturbance correction amount in a desired track based on the output signal stored in the storing means, and the calculating means. By including the correction output signal supplied from the means according to the position of the head arm and the original positioning control output signal for correction,
The problems described above are solved.

[0013]

The head arm drive device according to the present invention obtains and corrects the disturbance amount in a desired track as a correction amount based on the output signals detected at at least two or more different track positions in the circumferential direction on the recording medium. By doing so, the head arm is positioned stably, and in particular, the access time is stabilized.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a head arm drive device according to the present invention will be described with reference to the drawings.

The head arm drive device of the present invention will be described with reference to the schematic circuit configuration shown in FIG. The head arm drive device is also a position signal detection unit 11 that is also a detection unit that detects a disturbance amount at at least two or more different track positions in the circumferential direction on the recording medium on the recording medium.
And a RAM 12 that is a storage unit that stores the output signal from the position signal detection unit 11, and a digital signal processing unit that is a calculation unit that calculates the disturbance correction amount in a desired track based on the output signal stored in the RAM 12. (Hereinafter abbreviated as DSP) 13, and a DSP 13 capable of adding data by software as a correction means for adding and correcting the correction output signal supplied from the DSP 13 according to the position of the head arm and the original positioning control output signal.
It is configured using.

The position signal detecting section 11 includes an R / W amplifier 15, an equalizer 16, an envelope detecting circuit 17, and a pulse detecting circuit 1 for amplifying a read / write signal.
8, a servo detection circuit 19, an integration circuit 20, an A / D converter 21, and a position information generation circuit 22. When the head arm 23 is positioned, the position signal detecting section 11 reproduces a sector servo pattern (SSP) written at equal intervals on tracks in the circumferential direction on the disk 24 which is a recording medium, and this sector Positioning control is performed based on the position information obtained from the servo pattern.

The disk 24 is a mounting table (not shown).
The spindle motor 25 is mounted on and is rotating.
The sector servo pattern (SS is necessary for positioning the target position from the rotating disk 24.
The detection signal from P) is supplied to the R / W amplifier 15 via the flexible cable 27 via the head 26 at the tip of the head arm 23 which is a part of the actuator.

The R / W amplifier 15 amplifies and supplies the detection signal to the equalizer 16. In the equalizer 16, the supplied detection signal is waveform-shaped and supplied to the envelope detection circuit 17 and the pulse detection circuit 18. The pulse detection circuit 18 sends the detected pulse signal to the servo detection circuit 19.

The servo detection circuit 19 sends address-related information from the detection signals from the sector servo pattern to the position information generation circuit 22 and also supplies a peak detection timing signal to the envelope detection circuit 17. Further, the servo detection circuit 19 supplies a charge timing and discharge timing signal and a switching timing signal to an integration circuit 20 and an A / D converter 21, which will be described later.

The output signal of the equalizer 16 is input to the envelope detection circuit 17. The envelope detection circuit 17 detects the level of the envelope signal by supplying the peak detection timing signal and supplies the peak level signal to the integration circuit 20. The integrating circuit 20 outputs the output signal controlled according to each timing of the charge timing and the discharge timing signal to the A / D converter 2
Supply to 1.

The A / D converter 21 outputs an output signal according to the switching timing signal, and a position information generating circuit 22.
Send to. The position information generation circuit 22 includes the A / D converter 2
Information on the head position is output according to the fine pattern from the sector servo pattern supplied from No. 1 and the address supplied from the servo detection circuit 19. This position information is sent to RA via the 16-bit DSP bus.
Send to M12 for temporary storage. The stored position information is stored in the controller (hereinafter, CPU) that controls the DSP 13.
It will be taken into the DSP 13 by a control signal from the. The CPU 28 bidirectionally supplies control signals to the DSP 13 for control.

The DSP 13 is supplied with the head arm 2
For the torque disturbance amount actually required according to the position information of 3, the disturbance compensation amount is calculated according to, for example, a linear approximation interpolation formula described later. The coefficient used in the linear approximation interpolation formula is obtained from the output control signal measured at startup. This coefficient is sent to the RAM 12 and stored therein.
In this way, when actually positioning the head arm 23 at an arbitrary position, the current position information is substituted into the interpolation formula to approximately obtain the disturbance compensation amount for the torque disturbance. This disturbance compensation amount and the data of the control output based on the normal positioning control method are added by software in the DSP 13. The added control output data is supplied to the D / A converter 14 via the DSP bus.

The D / A converter 14 converts the control output data relating to the above two positionings into an analog signal and outputs the control signal to the low pass filter (LPF) 29. This control signal is sent to the voice coil motor (VCM) drive circuit 30 via the low pass filter 29. The voice coil motor drive circuit 30 supplies a control current for driving the voice coil motor 31. The voice coil motor 31 sends the head arm 23 to a target position so as to compensate the torque disturbance described above according to the control current.

Next, the procedure for measuring so-called torque disturbance and the procedure for calculating the coefficient of torque disturbance will be described with reference to the measurement flowchart shown in FIG. 2 and the graph showing the torque disturbance with respect to the head arm position in FIG. The measurement of the torque disturbance in the flowchart shown in FIG. 2 is performed, for example, at the innermost and outermost tracks of the disk when the apparatus is started.

In step S10, the measurement of the torque disturbance is started, and the process proceeds to step S11. In step S11, the head arm 23 is moved to the outermost track position by the normal positioning control method so that the head arm 23 follows the target track center position. At this time, if the head arm position does not change, the torque disturbance appears as a constant torque disturbance like direct current (DC) peculiar to the apparatus shown in FIG. Since the control signal output to the voice coil motor drive circuit 30 when following the target track center position is output against the torque disturbance, the torque compensation amount at the outermost position is controlled as described above. Will be equal to the signal.

Next, in step S12, the measured value (CNT1) at the outermost circumference is taken as an average value obtained by measuring the control signal for one round. This average value is shown in Figure 1.
It is supplied to and stored in the RAM 12 shown in FIG. At the track address Trk0 of the outermost periphery (OD) shown in FIG. 3, the average value (CNT1) is negative. This negative value indicates that the torque disturbance force is acting on the outside of the disk.

In step S13, the head arm 23 is moved to the outermost track position by the normal positioning control method, and the head arm 23 is moved to the target track center position.
To follow. If it is in the same torque disturbance situation as in step S11 in step 14, the control signal which is the torque disturbance is measured for one round in the innermost circumference as described above, and is supplied to the RAM 12 shown in FIG. 1 as an average value (CNT2). And remember. At the track address TrkXf of the innermost circumference (ID) shown in FIG. 3, the average value (CNT2) shows a positive value. This positive value indicates that the torque disturbance force is acting on the inside of the disk.

The torque disturbance is measured from the outermost circumference, but it may be measured from the innermost circumference. Further, when the control output does not show such a large change over one round when the positioning is accurately performed, only the control signal of one sector or the average value of the control signals of several sectors may be used. .. Zero of the torque disturbance amount shown in FIG. 3 indicates a mechanical midpoint with respect to the torque disturbance.

In step S15, the torque disturbance at an arbitrary track address X is obtained from the two average values measured over one turn. For this reason, a track address is given to the disc inward from the outermost position OD of the disc. For example, the above-mentioned Trk0 and TrkXf at the outermost circumference and the innermost circumference are the track addresses. When this track address is used, the distance between the outermost circumference and the innermost circumference is expressed as Xf. Further, assuming that an arbitrary track address X is used, when linear approximation is performed, a linear inclination for calculating an approximate linear compensation amount for an arbitrary track address X by a linear interpolation formula shown below and a coefficient a indicating a straight line intercept,
The torque compensation amount CNT is calculated using b.

CNT = a × X + b (1) Here, the coefficients a and b are respectively expressed as a = (CNT2-CNT1) / Xf (2) b = CNT1 (3). This coefficient b is the outermost circumference (OD) shown in FIG.
Is the compensation amount at Trk0. The two coefficients a and b are sent to the RAM 12 and stored therein.

In step S16, the measurement of this torque disturbance is completed.

A procedure for positioning the head arm 23 at an arbitrary position after the above-mentioned setting is completed will be described with reference to the flowchart shown in FIG. 4 and the block diagram shown in FIG. 1 and the graph shown in FIG. 3 as necessary. .. In the flowchart shown in FIG. 4, a positioning routine in which torque disturbance is compensated at an arbitrary position of the head arm 23 is started in step S20.

In step S21, the current position information is obtained from the reproduced signal of the sector servo pattern obtained intermittently in the positioning control of the head arm 23. The track address X, which is the current position information, is substituted into the linear approximation interpolation formula to substitute the torque disturbance interpolation amount CNT at this position.
And proceeds to step S22. In step S22, the control signal obtained by adding the control signal obtained according to the normal positioning control method to the torque disturbance interpolation amount CNT by the DSP 13 is output to the D / A converter 14 shown in FIG.

In step S23, this torque disturbance compensation routine for compensating according to the torque disturbance amount at the present position of the head arm is ended.

The control signal output to the D / A converter 14 is a digital signal. The D / A converter 14 converts this digital signal into an analog signal and outputs it to the low-pass filter 29. This output signal is supplied to the voice coil motor drive circuit 30 via the low pass filter 29 as a control signal for driving the voice coil motor. This control signal is a control signal that has been compensated for the offset voltage and various torque disturbances shown in FIG. The voice coil motor drive circuit 30 supplies the drive signal in which the torque disturbance is compensated by the supply of the control signal to the voice coil motor 31.
Output to.

By supplying this drive signal, the voice coil motor 31 controls the head arm 23 to the target position.

The torque disturbance compensation at the current head arm position is not limited to the method based on the software procedure described above, but may be performed by the hardware shown in FIG. Here, common parts are given the same reference numerals, and description thereof is omitted. In this method, a control signal obtained from the DSP bus relating to the current position information of the head arm 23 according to a normal positioning control method is supplied to the first PWM circuit 40, and similarly, the torque disturbance interpolation amount CNT is supplied to the second PWM circuit 40 from the DSP bus. Is supplied to the PWM circuit 41, and these two signals are analog-added to the addition amplifier 43 and output. As the output signal from the adding amplifier 42, a signal for compensating the torque disturbance at the current position of the head arm 23 is supplied to the voice coil motor drive circuit 30 via the low pass filter 29.

By controlling the voice coil motor 29 in this manner, it is possible to suppress the torque disturbance generated in the head arm 23. First PWM circuit 4 described above
The first and second PWM circuits 42 use the D used in the above-described method.
Alternatively, two A / A converters may be used to convert the signals into analog signals and the addition amplifier 42 may add the analog signals.

The arrow T shown in FIG. 6 indicates the traveling direction of the time axis T. FIG. 6A shows a sector servo pattern SSP that appears intermittently. The normal control output and the control output for torque disturbance compensation shown in FIG. 6B are output to the sector servo pattern SSP at time-divisional timings in which the output times are shifted at respective sampling intervals S _C , S _TRQ for obtaining position information. By adopting the method described above, it is possible to omit one D / A converter that outputs an analog signal.

Although the above-described interpolation approximation uses linear approximation, the interpolation method is not limited to this approximation.
For example, a quadratic curve, a cubic curve, or polynomial approximation may be used depending on the situation of the torque disturbance.

Further, the head arm drive device of the present invention is
Unlike the conventional drive device, the coefficient is not always fixed to the coefficient before shipment, but the interpolation coefficient can be measured as needed. The measurement of this interpolation coefficient was performed at the time of starting the disk device in the above-mentioned measurement procedure, but changes in environmental conditions such as when the offset voltage in the device became stable after power-on, or when the temperature inside the device increased. It is possible to measure and respond to changes according to.

[0042]

As is apparent from the above description, according to the head arm driving device of the present invention, in the head arm driving device for controlling the positioning of the head, at least two or more different circumferential directions on the recording medium are provided. Detecting means for detecting the amount of disturbance at the track position, storage means for storing an output signal from the detecting means, and a disturbance correction amount for a desired track based on the output signal stored in the storage means Controlling the voice coil motor driver by adding a correction output signal supplied from the calculation means according to the position of the head arm and a correction means for adding and correcting the original positioning control output signal. Therefore, even if an external ROM or the like is not used, the change depends on the individual electric influence of the device and the position of the head arm, which is so-called torque disturbance. The influence of the external force can be canceled.

Further, by appropriately updating the disturbance compensation amount when the disk device is started or when the environmental change such as temperature rise is large, the positioning can be performed without any problem even after the environmental change after shipping. Can be controlled.

[Brief description of drawings]

FIG. 1 is a schematic circuit diagram of an embodiment of a head arm drive device according to the present invention.

FIG. 2 is a flowchart showing a procedure for measuring torque disturbance coefficient data.

FIG. 3 is a graph showing a relationship between a torque disturbance compensation amount and a linear approximation interpolation amount at each track address.

FIG. 4 is a flowchart showing a procedure of performing torque compensation when positioning the head arm at an arbitrary position.

FIG. 5 is a simplified block diagram showing a method of adding a control output in normal positioning and a control output for torque compensation by hardware.

FIG. 6 is a schematic diagram illustrating positioning control in the case where a control output in normal positioning and a control output for torque compensation are supplied in a time division manner to a sector servo pattern that supplies current position information.

FIG. 7 is a configuration diagram of a conventional hard disk device.

[Explanation of symbols]

11 --- .. Position signal generator 12.- .. RAM 13 --- .. DSP 14-・ ・ ・ ・ ・ ・ ・ ・ D / A converter 19 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Servo detection circuit 21 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ A / D converter 22 ・ ・ ・・ ・ ・ ・ ・ ・ ・ ・ Position information generation circuit 23 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Head arm 26 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Head 27 ・ ・ ・ ・ ・ ・・ ・ Flexible cable 28 ・ ・ ・ ・ ・ ・ ・ CPU 29 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ LPF 30 ・ ・ ・ ・ ・ ・Coil motor (V
CM) Drive circuit 31 ... Voice coil motor

Claims (1)

[Claims] 1. A head arm drive device for controlling the positioning of a head, comprising: detection means for detecting the amount of disturbance at at least two or more different track positions in the circumferential direction on a recording medium; Storage means for storing an output signal, calculation means for calculating a disturbance correction amount in a desired track based on the output signal stored in the storage means, and correction output supplied from the calculation means according to the position of the head arm A head arm drive device comprising: a correction unit that adds and corrects a signal and an original positioning control output signal.