JPH07122011A - Magnetic head positioning control device - Google Patents

Abstract

PURPOSE:To obtain a good following property after a target track of a magnetic head by strengthening holding force of a step motor and also compensating disk eccentricity and positional errors of the motor and a position sensor relative to a track position. CONSTITUTION:A main loop controller is composed of a position error detector 4 for obtaining a position error signal showing a difference between a target position of the magnetic head 3 and a position of the magnetic head 3 at each predetermined sampling time, an integrator 5 for integrating the above output, a switch 9 for breaking an output of the integrator 5 at the time of moving the magnetic head 3 to a different track and an adder 7 for outputting a minor loop target position from the output of the integrator 5 and a value of the target position. Then, a minor loop controller is composed of a position detector 6 for detecting a motor position of the step motor 2, a subtractor 8 for obtaining a difference between the above output and the minor loop target position and a motor drive amplifier 1 for controlling the step motor 2 in motion.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic head positioning controller, and more particularly to a magnetic head positioning controller for a floppy disk drive using a sector servo system.

[0002]

2. Description of the Related Art In a floppy disk drive, the capacity is increased by narrowing the track pitch by the sector servo system. As is well known as the sector servo system, information about the position to be followed by the magnetic head is recorded on the surface of the magnetic disk in advance at the head of the sector or at the rear end of the sector, and this information is reproduced by the magnetic head to obtain a position error signal. Is a positioning control method based on so-called sample value information for positioning the magnetic head on the target data track.

However, in the sector servo system, since information about the position to be followed by the magnetic head can be obtained only on a sample basis, there is a drawback that feedback control does not work between sample points and the external force is weak.

As a method for solving this drawback, Japanese Unexamined Patent Publication No.
There is a control method as disclosed in Japanese Patent No. 88183.

[0005]

[Patent Document 1] Japanese Patent Application Laid-Open No. 3-88183
The control method described in the publication uses both continuous motor feedback control using an external position sensor that detects the motor position and magnetic head positioning control based on a sampled position error signal, and the sampling frequency is It is a control method that obtains good follow-up characteristics of a magnetic head that has a strong holding force against an external force even when it is low.

However, in this control system, the position control is first performed between the target position and the external position sensor, and then the average position error value is calculated from the position error signal obtained from the reproduction signal of the magnetic head. Then, the magnetic head is positioned and controlled at the target position by superimposing the obtained average value on the target position value. Therefore, when the magnetic head is positioned at the target position, the position error value of the position error signal becomes zero,
Since the average value to be superposed is also zero, the target position returns to the value initially positioned using the external position sensor, and the magnetic head has a drawback that it deviates from the target position.

The object of the present invention was devised in view of the above-mentioned drawbacks, and is characterized in that it integrates a position error signal obtained from a magnetic head and holds an operation amount for causing the magnetic head to follow a target position. Another object of the present invention is to provide a magnetic head positioning control device for a floppy disk device, which has a strong holding force against external force and can realize good magnetic head following characteristics even when the sampling frequency is low.

[0008]

SUMMARY OF THE INVENTION The present invention is a positioning control device using a step motor for a magnetic head positioning mechanism, wherein the difference between the target position for positioning the magnetic head and the position of the magnetic head is determined. A position error detector that obtains the position error signal shown at each predetermined sampling time, and an integrator that integrates the output of the position error detector,
Main loop control including a switch that shuts off the output of the integrator when the magnetic head moves to a different track, and an adder that outputs a minor loop target position from the output of the integrator and the value of the target position A position detector for detecting the motor position of the step motor, a subtractor for obtaining a difference between the output of the position detector and the minor loop target position, and an operation of the step motor from the output of the subtractor. A minor loop controller having a motor drive amplifier for controlling; and a minor loop controller.

[0009]

The magnetic head positioning controller of the present invention integrates the position error signal obtained discretely with respect to the target position of the position control system using the position sensor for measuring the position of the step motor for driving the magnetic head. By adding the values, the holding force of the step motor is strengthened, the disk eccentricity and the error of the motor and the position sensor with respect to the track position are compensated, and a good target track following characteristic of the magnetic head is realized.

[0010]

The present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram showing the configuration of a magnetic head positioning control device according to an embodiment of the present invention. The magnetic head positioning device of the present invention, as shown in FIG.
A position error detector 4 that obtains a position error signal indicating the difference between the target position 701 and the position of the magnetic head 3 at each predetermined sampling time, an integrator 5 that integrates the output of the position error detector 4, and a magnetic A switch 9 that shuts off the output of the integrator 5 when the head 3 moves to a different track.
And the integrated value 501 output from the integrator 5 and the target position 70
The main loop controller is composed of the adder 7 that outputs the minor loop target position 702 from the value of 1 and the position detector 6 that detects the motor position of the step motor 2, and the output of the position detector 6 and the minor loop. The minor loop controller includes a subtracter 8 that obtains a difference from the target position 702 and a motor drive amplifier 1 that outputs a step motor control signal to the step motor 2 by using the output of the subtractor 8.

In this magnetic head positioning control device, the switch 9 is open when the magnetic head 3 moves to a different track. Further, the sampling period of the main loop is T1, the sampling period of the minor loop is T2, and the mutual relationship is a period in which T2 is sufficiently shorter than T1. Since the switch 9 is open, the target position 701 of the step motor 2 and the minor loop target position 702 are equal. The minor loop target position 702 is input to the subtractor 8 together with the output value 601 of the position detector 6 that measures the position 201 of the step motor. The position detector 6 is a detector that numerically outputs a position error value represented by an encoder or the like. The minor loop target position 702 and the output value 601 of the position detector 6 are subtracted by the subtractor 8 and their error value 8
01 is output. Then, the output error value 801 is given to the motor drive amplifier 1 every sampling period T2.

The motor drive amplifier 1 comprises a microstep drive circuit as shown in FIG. The control unit 11
From the error value 801 input for each sampling cycle T2, the motor operation amount 103 that brings the error value 801 closer to the zero is output. The motor operation amount 103 is input to read-only memories (ROM) 12 and 13 that store the amount of current applied to the two-phase step motor as a digital table, and the digital operation value 104 corresponding to the motor operation amount 103, 105 is output. The digital operation values 104 and 105 output from the ROMs 12 and 13 are converted into analog operation values by the D / A converters (D / A) 14 and 15, respectively, and the two-phase current command values 101 and 101 are converted by the current amplifiers 16 and 17, respectively. The step motor 2 is driven by being amplified by 102, and the position information 201 of the step motor 2 follows the minor loop target position 702.

Next, when following the data track, the switch 9 is closed. Generally, since the data track is eccentric at the same frequency as the disk rotation frequency and twice the frequency, it is necessary to follow the eccentricity. The magnetic head 3
The reproduced signal 301 read from the recording medium is output to the position error detector 4 at every sampling period T1. The position error detector 4, as shown in FIG. 4, detects the position information recorded on the medium surface as follows. For example, when the magnetic head 3 is displaced inward from the center of the track 41, the reproduction signal output of the position data 42, 43 is inversely proportional to the distance from the magnetic head 3, so the reproduction signal output of the position data 42 is Becomes larger and the difference between the signal outputs of the two becomes greater, so that the position error value 401 which is the offset amount between the magnetic head 3 and the center of the track 41 can be detected. The detected position error value 401 is output to the integrator 5.

The integrator 5 is, as shown in FIG.
1 and a register 82. The adder 51 adds the detected position error value 401 to the value one sample before stored in the register 52. Then, by holding the added value in the register 52, the position error value 4
An integrated value 501 obtained by integrating 01 is obtained. The obtained integrated value 501 is output to the adder 7 via the switch 9.
Then, the integrated value 501 is added to the target position 701 by the adder 7.
Minor loop target value 7 that is added to
02 is obtained.

The step motor 2 based on the obtained minor loop target position 702 and the output value 601 of the position detector 6
By the feedback control of 1), the magnetic head 3 can be positioned with high accuracy in the target position track. Since the relationship of the sampling period is T2 << T1, the control band of the minor loop is wider than the control band of the main loop, a high error compression rate is obtained at the eccentric frequency, and the holding force against the external force is also the main loop alone. Significantly better than the ones.

[0016]

As described above, according to the present invention, the position error obtained discretely with respect to the target position of the position control system using the position sensor that measures the position of the step motor that drives the magnetic head. By adding the integrated value of the signal, it is possible to strengthen the holding force of the step motor, compensate for the disc eccentricity and the error of the motor and position sensor with respect to the track position, and achieve good target track following characteristics of the magnetic head. There is.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention.

FIG. 2 is a block diagram showing details of a step motor drive amplifier 1 in FIG.

3 is a block diagram showing details of an integrator 5 in FIG. 1. FIG.

FIG. 4 is a diagram illustrating a relationship between a magnetic head and position data.

[Explanation of symbols]

 1 Motor Drive Amplifier 2 Step Motor 3 Magnetic Head 4 Position Error Detector 5 Integrator 6 Position Detector 7,51 Adder 8 Subtractor 9 Switch 11 Controller 12,13 Read Only Memory (ROM) 14,15 D / A Converter (D / A) 16, 17 Current amplifier 41 Track 42, 43 Position data 52 Register 101, 102 Current command value 103 Motor operation amount 104, 105 Digital operation value 201 Position information 301 Playback signal 401 Position error value 501 Integrated value 601 Output value 701 Target position 702 Minor loop target position 801 Error value

Claims (1)

[Claims] 1. A positioning control device using a step motor for a magnetic head positioning mechanism, wherein a position error signal indicating a difference between a target position for positioning the magnetic head and the position of the magnetic head is predetermined. A position error detector obtained for each sampling time, an integrator that integrates the output of the position error detector, a switch that shuts off the output of the integrator when the magnetic head moves to a different track, and the integration Loop controller including an adder for outputting a minor loop target position from the value of the target position and the value of the target position; a position detector for detecting the motor position of the step motor; and an output for the position detector and the A subtractor for obtaining the difference from the minor loop target position and a motor drive amplifier for controlling the operation of the step motor from the output of the subtractor are provided. That minor loop controller and; a magnetic head positioning control apparatus characterized by comprising a.