JPH0279275A - Magnetic head movement controller - Google Patents

Abstract

PURPOSE:To reduce a differentiating circuit and a switching circuit, to simplify circuit constitutions, and to obtain a real speed signal at the time of high-speed moving of a magnetic head by detecting the moving speed of the magnetic head from a track width. CONSTITUTION:A position signal preparing means 31, which prepares the position signal corresponding to the current position of a data head based on a servo signal outputted from a servo head, a speed detecting signal, which detects the track width based on the position signal outputted from the means 31 and detects the moving speed of a carriage mechanism according to the track width, etc., are provided. Further, the difference between a target speed and the moving speed detected by the speed detecting means 36 is obtained, a current in proportion to the difference is supplied to a voice coil motor, and the said carriage mechanism is driven. Thus, the circuit is made to be simplified and the real speed signal can be obtained at the time of high-speed moving of the magnetic head.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention particularly relates to a magnetic head movement control device for controlling movement of a magnetic head used in a magnetic disk device.

(Prior Art) Conventionally, in a magnetic disk drive, a magnetic head is moved by mounting several heads together on a carriage and driving them from the rear with an actuator. This drive is performed by a voice coil motor (VCM), and the movement is controlled by a track servo.

This movement control includes an operation of moving at high speed by accelerating and decelerating according to a speed curve set in advance for the target track while performing speed control, and an operation of following the target track without positional deviation.

A conventional head movement control device will be explained using a servo surface servo type magnetic disk device shown in FIG.

In FIG. 3, the carriage 13 is a data head 12a.
and a servo head 12b, which is moved in the radial direction of the disk 10 by the driving force of a voice coil motor (VCM) 14. The data head 12a is the disk 10
This is a magnetic head that writes/writes data to/from the data surface 10a. The servo head 10b is a magnetic head for reproducing servo information previously recorded on the servo surface 10b. The disk 10 is rotated by a spindle motor 11.

The voice coil motor 14 is a rotary type carriage 1.
3, and is driven and controlled by a movement control system. The movement control system includes a servo circuit 13 and a VCM drive circuit 15. VCM drive circuit 15
supplies a drive current (current proportional to the speed error signal) to the voice coil motor 13 in an amount and direction according to a speed error signal from a movement control error signal generation circuit 26, which will be described later.

Further, the VCM drive circuit 15 supplies a drive current (a current proportional to the error signal) to the voice coil motor 13 in an amount and direction according to an error signal from a fine control error signal generation circuit 27, which will be described later.

As shown in FIG. 4, the servo circuit 13 includes a position signal generation circuit 21, a differentiation circuit 22, . . . , an analog switch 2
3,..., 28, microprocessor (CPU) 24
, D/A converter 25, movement control error signal generation circuit 26,
and a fine control error signal generation circuit 27.

The position signal generation circuit 21 generates four position signals (0 degrees, 90 degrees, 18 degrees) with different phases corresponding to the current position of the data head 12a based on the servo signal from the servo head 12a.
0 degrees, 270 degrees) (see Figure 5), and each position signal is generated by a differentiating circuit 22 as a speed detection circuit,...
The one-phase position signal (0 degree) is output to the fine control error signal generation circuit 27. Position signal generation circuit 2
1 is a cylinder pulse C every time one track is crossed.
Output to PU24. The differentiating circuits 22, . . . generate speed signals based on position signals having different phases from the position signal generating circuit 21, and the analog switches 23, .
The signal is outputted to the movement control error signal generation circuit 26 and the fine control error signal generation circuit 27 via . The movement control error signal generation circuit 26 generates a speed error signal corresponding to the error between the detected speed signal from the analog switch 23 and the target speed supplied from the CPU 24 to the analog switch 28.
The signal is output to the VCM drive circuit 15 via the VCM drive circuit 15.

Each time the CPU 24 receives a cylinder pulse from the position signal generation circuit 22, the CPU 24 executes an interrupt processing program,
Update the target speed. That is, the CPU 26 counts cylinder pulses from the position signal generation circuit 21, and calculates the difference between the current track (current position) determined by this count value and the target track (target cylinder) supplied from a host computer (not shown). The corresponding target speed data is read from a memory (not shown), and the D/A converter 2
Set to 5. The D/A converter 25 converts the target speed set by the CPU 24 into a voltage signal and outputs it to the movement control error signal generation circuit 26.

Next, the operation of the above output will be explained. A target track is supplied to the CPU 24 from a host computer (not shown). Then, the CPU 24 stores the cylinder pulse count value from the position signal generation circuit 21, that is, the target speed data corresponding to the difference between the current track and the target track, in the memory (
(not shown) and set it in the D/A converter 25. The voltage signal corresponding to the target speed data set in the D/A converter 25 is transmitted to the moving speed error signal generating circuit 26.
Output to.

Further, the position signal generation circuit 21 generates a position signal corresponding to the current position of the data head 12a based on the servo signal from the servo head 12b, and outputs it to the differentiating circuit 22, . The differentiating circuits 22, . The moving speed error signal generation circuit 26 outputs a speed error signal corresponding to the error between the detected speed signal and the target speed data from the D/A converter 25 to the VCM drive circuit 15 via the analog switch 28. VCM drive circuit 15
supplies a drive current to the voice coil motor 14 in an amount and direction corresponding to the speed error signal. Thereby, the voice coil motor 14 moves the carriage 13, that is, the data head 12a, in the direction of the target track in accordance with the target speed.

From then on, until the data head 12a reaches the target track, the target speed data is updated every time a cylinder pulse is supplied, and the data head 12a is moved in the direction of the target track under speed control corresponding to this process. do.

Then, the CPU 24 moves the data head 12 to the target track.
When it is determined that a has arrived, the analog switch 28
Switch to fine control side. At this time, a speed signal is created by differentiating the one-phase position signal from the position signal creation circuit 21 using one differentiating circuit 22, and is outputted to the fine control error signal generation circuit 27 via the analog switch 23. There is. The fine control error signal generation circuit 27 is also supplied with a position signal (with a phase difference of 0 degrees) from the position signal generation circuit 21 . Thereby, the fine control error signal generation circuit 27 outputs an error corresponding to the deviation from the target stop position using the speed signal and the position signal. This error signal is passed through the analog switch 28 to the VC
The signal is output to the M drive circuit 15. The VCM drive circuit 15 supplies a drive current to the voice coil motor 14 in an amount and direction according to the error signal. As a result, the voice coil motor 14 moves the carriage 13, that is, the data head 12a.
Move to the target stop position.

(Problems to be Solved by the Invention) In the conventional magnetic head movement control device, 4
Since the speed signal was detected by creating position signals with two different phases, performing differentiation for each phase, and connecting the true values of each phase, many circuits were required. In addition, when creating a speed signal using a position signal, if the magnetic head is moving at high speed, the position signal is created by sampling servo data, and a low-pass filter is used to remove high frequency noise, so it may be false. There is also a drawback that the signal becomes a speed signal and it is not possible to obtain a true speed signal.

SUMMARY OF THE INVENTION An object of the present invention is to provide a magnetic head movement control device that has a simplified circuit and can obtain a true speed signal when the magnetic head moves at high speed.

[Output of the Invention] (Means for Solving the Problem) A magnetic head movement control device of the present invention includes a data head that reads and writes data from a data surface having a plurality of tracks of a magnetic recording medium, and a data surface that reads and writes data from a data surface having a plurality of tracks. a servo head that reads a servo signal for head positioning control from a servo surface having the same track spacing as the track spacing of
A carriage mechanism that simultaneously moves the data head and the servo head, a voice motor coil that drives the carriage mechanism, and a position signal corresponding to the current position of the data head based on a servo signal output from the servo head. a position signal generating means for generating a track width; a width detecting means for detecting the width of the track based on a device signal output from the position signal generating means; speed detecting means for detecting the moving speed; determining means for determining the current position of the data head based on a device signal output from the position signal generating means; An output means for outputting a target speed corresponding to a difference from a target track to be moved, a difference between the target speed from this output means and the moving speed detected by the speed detection means, and a current proportional to this difference. a first control means for controlling movement of the data head to a target track by supplying the voice coil motor to the voice coil motor and driving the carriage mechanism; and differentiating a device signal output from the position signal generating means; differentiating means for creating a velocity signal by; and when the current position of the data head corresponds to a target track;
A current based on a speed signal created by the differentiating means and a device signal output from the position signal creating means is supplied to the voice coil motor to drive the carriage mechanism, thereby moving the data head to the target track. It is output from the second control means that performs follow-up movement control.

(Function) Since the present invention detects the moving speed of the magnetic head from the track width, the circuit can be simplified by reducing the number of differentiating circuits and switching circuits, and the true speed signal can be detected when the magnetic head is moving at high speed. can be obtained.

(Example) An example of the present invention will be described below with reference to the drawings. 1st
The figure is a block diagram showing the output of the Sanibo circuit of the same embodiment. FIG. 2 is a block diagram showing a partial output of the magnetic disk device according to the same embodiment, and the same parts as in FIG. 3 are given the same reference numerals and explanations will be omitted. However, in FIG. 2, the output of the servo circuit 30 has been changed as shown in FIG.

As shown in FIG. 1, the servo circuit 30 includes a position signal generation circuit 31, a differentiation circuit 32, a fine control error signal generation circuit 33, an on-cylinder detection circuit 34, an oscillator 35, a speed detector 36, a CPU 37, and a D/A. It consists of a converter 38, a gain adjuster 39, and an analog switch 40.

The position signal generation circuit 31 generates a position signal (0 degrees) corresponding to the current position of the data head 12a based on the servo signal from the servo head 12b,
It is output to the fine control error signal generation circuit 33 and the on-cylinder detection circuit 34. The differentiating circuit 32 detects a speed signal by differentiating the device signal output from the position signal generating circuit 31, and outputs the fine control error signal generating circuit 33.
Output to. The fine control error signal generation circuit 33 uses the speed signal from the differentiating circuit 32 and the position signal from the position signal generation circuit 31 to drive the VCM via the analog switch 40 with an error signal corresponding to the deviation from the target stop position. Output to circuit 15. The on-cylinder detection circuit 34 creates a pulsed on-cylinder signal (track crossing signal) based on the position signal from the position signal creation circuit 31, and outputs it to the speed detector 36 and the CPU 37. Oscillator 35
generates clock pulses and outputs them to speed detector 36. The speed detector 3 measures the interval (track width) of the on-cylinder signal from the on-cylinder detection circuit 34 using a clock pulse from the oscillator 35, and outputs a detected speed signal corresponding to the measurement result to the CPU 37. CPU3
Reference numeral 7 reads the cylinder pulse count value from the on-cylinder detection circuit 34, that is, the target speed data corresponding to the difference between the current track and the target track, from a memory (not shown), and reads out the read target speed data and the speed detector. 36
The speed difference between the detected speed signal and the detected speed signal is calculated, and a speed error signal corresponding to the speed difference is output to the D/A converter 38.

The D/A converter 38 outputs a voltage signal corresponding to the target error signal from the CPU 37 to the gain adjuster 39. The gain adjuster 39 adjusts the gain of the voltage signal from the D/A converter 38 and then outputs it to the VCM drive circuit 15 via the analog switch 40.

Next, the operation of this embodiment will be explained. A target track is supplied to the CPU 37 from a host computer (not shown). Then, the CPU 37 reads out the cylinder pulse count value from the on-cylinder detection circuit 34, that is, target speed data corresponding to the difference between the current track and the target track, from a memory (not shown), and controls the analog switch 40 to control the speed. In other words, the signal from the gain adjuster 39 is output.

Further, the position signal generation circuit 31 generates a position signal corresponding to the current position of the data head 12a based on the servo signal from the servo head 12b, and generates a position signal corresponding to the current position of the data head 12a.
Output to 4. The on-cylinder detection circuit 34 creates a pulsed on-cylinder signal based on the position signal and outputs it to the speed detector 36. The speed detector 36 measures the interval between the on-cylinder signals using the clock pulse from the oscillator 35, and outputs a detected speed signal corresponding to the measurement result to the CPU 37.

Thereby, the CPU 37 calculates the speed difference between the target speed data and the detected speed signal, and outputs a speed error signal corresponding to the speed difference to the D/A converter 38. The D/A converter 38 converts the supplied speed error signal from a digital value to an analog value and outputs it to the gain adjuster 39. The speed error signal from gain adjuster 39 is output to VCM drive circuit 15 via analog switch 40. The VCM drive circuit 15 supplies a drive current to the voice coil motor 14 in an amount and direction according to the speed error signal.

As a result, the voice coil motor 14 moves to the carriage 13.
That is, the data head 12a is moved in the target track direction in accordance with the target speed.

Thereafter, the data head 12a is controlled at a speed corresponding to the above processing until the data head 12a reaches the target track.
a toward the target track.

Then, the CPU 37 moves the data head 12 to the target track.
When it is determined that a has arrived, the analog switch 40
Switch to fine control side.

At this time, the position signal generation circuit 31 generates a position signal (phase difference of 0 degrees) corresponding to the current position of the data head 12a based on the servo signal from the servo head 12b, and outputs it to the differentiation circuit 32. Differentiating circuit 32 detects a speed signal by differentiating the position signal, and outputs it to fine control error signal generating circuit 33 . The fine control error signal generation circuit 33 is also supplied with a position signal from the position signal generation circuit 31 . Thereby, the fine control error signal generation circuit 33 outputs an error signal corresponding to the deviation from the target stop position based on the speed signal and the position signal. This error signal is output to the VCM drive circuit 15 via the analog switch 40.

The VCM drive circuit 15 supplies a drive current to the voice coil motor 14 in an amount and direction according to the error signal. Thereby, the voice coil motor 14 moves the carriage 13, that is, the data head 12a, to the target stop position.

As mentioned above, the detected speed signal used to control the movement of the magnetic head is not obtained by differentiating the position signal, but is obtained from the on-cylinder interval, that is, the track width, which reduces the number of differentiating circuits and analog switches. In other words, the circuit can be simplified. Furthermore, since the speed is detected at intervals equal to the width of the on-cylinder, that is, the track, a true speed signal can be obtained even when the magnetic head is moving at high speed.

[Effects of the Invention] As described in detail above, according to the present invention, it is possible to simplify the circuit and obtain a true speed signal when the magnetic head moves at high speed.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the output of a servo circuit according to an embodiment of the present invention, FIG. 2 is a block diagram showing a partial output of a magnetic disk device in the same embodiment, and FIG. 3 is a block diagram showing a partial output of a magnetic disk device according to the embodiment. Block diagram showing partial output, No. 4
5 is a block diagram showing the output of a conventional servo circuit, and FIG. 5 is a diagram for explaining position signals having different phase differences created by the position signal creation circuit in FIG. 4. 10... Disc, 10a... Data side, 10b.
...Servo surface, 12a...Data head, 12b...
・Servo head, 13... Carriage, 14... Voice coil mo') (VCM), 15-VCM drive circuit, 30... Servo circuit, 31... Position signal creation circuit, 32... Differentiation Circuit, 33... Fine control error signal generation circuit, 34... On-cylinder detection circuit, 35
...Oscillator, 36...Speed detector, 37...CP
U, 38...D/A converter, 39...gain adjuster,
40...Analog switch. Applicant's agent Patent attorney Takehiko Suzue Figure 3

Claims (1)

[Claims] A data head that reads and writes data from a data surface having multiple tracks of a magnetic recording medium, and a servo that reads servo signals for head positioning control from a servo surface that has the same track spacing as that of the data surface. a carriage mechanism that simultaneously moves the head, the data head and the servo head, a voice motor coil that drives the carriage mechanism, and a voice motor coil that responds to the current position of the data head based on a servo signal output from the servo head. a position signal generating means for generating a position signal, a width detecting means for detecting the width of the track based on the position signal output from the position signal generating means, and a width detecting means for detecting the width of the track based on the position signal output from the position signal generating means; speed detecting means for detecting the moving speed of the carriage mechanism; determining means for determining the current position of the data head based on the position signal output from the position signal generating means; and determining the current position of the data head by the determining means. an output means for outputting a target speed according to a difference between a position and a target track to which the data head should move; and a difference between the target speed from the output means and the moving speed detected by the speed detection means; A first control means for controlling the movement of the data head to a target track by supplying a current proportional to this difference to the voice coil motor and driving the carriage mechanism, and an output from the position signal generation means. a differentiating means for creating a speed signal by differentiating a position signal generated by the data head; and a differentiating means for creating a speed signal by differentiating a position signal generated by the differentiating means, and a speed signal created by the differentiating means and output from the position signal creating means when the current position of the data head corresponds to a target track. supplying a current based on the position signal to the voice coil motor to drive the carriage mechanism;
A magnetic head movement control device comprising: second control means for controlling movement of the data head to follow a target track.