JPS62114172A - Positioning device for magnetic disc device - Google Patents

Abstract

PURPOSE:To improve the tracking accuracy to an object track by providing a detector detecting the turning angle of a magnetic disc and a servo control circuit outputting an operation signal to a track shaped storage circuit and an actuator. CONSTITUTION:A magnetic head 2 detects the position fluctuation caused by the vibration of a magnetic track 1 passing through beneath the head 2. The fluctuation is inputted to a servo control circuit 3 as the position deviation between the head 2 and the track 1. The circuit 3 makes the deviation zero and an operation signal to trace the head 2 to an object track 1 is fed to an actuator 4 so as to adjust the position of the head 2 to the object track 1. The track 1 is formed to a shape different from a circle. The shape corresponds to the position on the circle of the disc, the reference position representing the correspondence is detected 5 in advance and a signal retarding the time corresponding to an angle between the detector 5 and the head 2 is inputted to a storage circuit 6. A signal corresponding to the shape of the track 1 is added 7 from the circuit 6 and the position of the head 2 is adjusted in matching with the shape of the track 1.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic disk drive, and more particularly to a positioning device for a magnetic disk drive suitable for improving the accuracy of track following servo control.

[Conventional technology]

In conventional magnetic disk devices, 1, for example, JP-A-51
As described in Publication No. 94204, the track on which the information was recorded was a circle. The track-following servo control circuit detects positional fluctuations caused by the vibrations of the track passing directly beneath the magnetic head to be positioned, and inputs this to the servo control circuit as a positional deviation between the magnetic head and the track. However, feedback control is basically used to drive the actuator so that the position of the magnetic head is adjusted so that this deviation becomes zero and the magnetic head follows the target track.

[Problem that the invention seeks to solve]

In the conventional example described above, the positional deviation may become extremely close to zero, and the positional deviation may become large from zero due to disturbance. In such a case, a state occurs in which the actuator is temporarily stopped or approximately stopped, and then rapidly accelerated from this state. Since the actuator that drives the bifurcated head is supported by mechanical contact, it will not be moved and will be able to follow the fluctuating track until a force that overcomes the frictional force of the contact area is applied. Furthermore, when a force that overcomes the frictional force is applied, a nonlinear phenomenon occurs in which the object suddenly moves out of control. These phenomena are extremely harmful to servo control for accurate tracking within +14FIIl and are one of the causes of a decline in tracking accuracy.

SUMMARY OF THE INVENTION An object of the present invention is to provide a positioning device for a magnetic disk drive that solves the nonlinear operation that occurs in the conventional track following operation and improves the accuracy of tracking a target track.

[Means for solving problems]

The above object of the present invention is to provide a magnetic disk positioning device for positioning a magnetic head on a magnetic track on a magnetic disk using an actuator, which includes a detector for detecting a rotation angle of a magnetic disk, and a sensor for storing a magnetic track on a magnetic disk. a storage means for continuously outputting the radial movement speed and movement acceleration of the magnetic disk of the magnetic head at a predetermined value or less according to the rotation angle of the magnetic disk from the detector; and a target signal from the storage means. This is achieved by including a servo control circuit that outputs an operation signal to the actuator based on the position signal of the magnetic head.

[Effect]

Read according to the rotation angle of the magnetic disk.

A magnetic head for writing reciprocates a predetermined distance in the radial direction of the magnetic disk, and targets the magnetic head by changing the moving speed and acceleration of the magnetic head in the radial direction of the disk four times continuously below a predetermined value. Follow the magnetic track.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows the configuration of a magnetic disk device equipped with an embodiment of the device of the present invention. In this figure, 1 is a reference position when reading or writing magnetic recording signals on a magnetic disk. This is a magnetic track, and one of the many magnetic tracks provided concentrically around the center O of the magnetic disk is shown. This magnetic 1-
If the magnetic head 2 is following the track without coming off the rack, no change in the position of the track will be detected, and there will be no relative positional deviation between the magnetic head and the track. However, because the magnetic disk rotates at high speed or because it is difficult to set the magnetic track accurately, the magnetic track 1 actually vibrates as shown by the solid line. magnetic head 2
detects the positional fluctuation caused by the vibration of the magnetic track 1 passing directly under it, and detects this by the magnetic head 2.
and the positional deviation of the magnetic track 1, the servo control circuit 3
Enter. The servo control circuit 3 applies an operation signal to the actuator 4 to make this deviation zero and cause the magnetic head 2 to follow the target track 1, thereby adjusting the position of the magnetic head 2 with respect to the target track. In the present invention, as will be described later, the magnetic track 1 is shaped differently from the conventional circular shape. This shape corresponds to the position on the circumference of the magnetic disk, and a reference position indicating this correspondence is detected in advance by the detector 5.
A signal is input to the memory circuit 6 to delay the time corresponding to the angle between the magnetic head 2 and the magnetic head 2. A signal corresponding to the shape of the magnetic track is applied from the storage circuit 6 to the addition circuit 7, and the position of the magnetic head 2 is adjusted in advance to match the shape of the magnetic track passing directly below it. In the present invention, by devising the shape of the magnetic track, the accuracy of tracking the target track can be improved compared to the conventional method even with only feedback control by the conventional servo control circuit 5, but the addition of such a feedforward control circuit 7 By doing so, even greater effects can be expected.

FIG. 2 shows an example of the shape of the magnetic track 1 used in the present invention, and shows the shape of the track centered on the center O of the magnetic disk. In the figure, the relationship between the radial position r of the magnetic track 1 from the magnetic disk center O and the angle 0 from the reference position S on the circumference is expressed by the following equation.

r=csjnO+Co ・=(1
) where C and Go are constants.

Therefore, the velocity in the radial direction is expressed by the following equation.

dod electric.

t becomes.

Further, the acceleration in the radial direction is expressed by the following equation.

Figure 3 shows the radial position r, velocity 1, acceleration α, and characteristics of the magnetic track 1 shown in Figure 2, and these are plotted when the circumference is expanded with the angle θ on the horizontal axis. It shows various quantities. From the figure, the shape of the magnetic track 1 is as follows. That is, (a) the magnetic head reciprocates within a predetermined distance in the radial direction of the disk, and changes continuously.

(b) The moving speed of the magnetic head in the radial direction of the disk repeats below a predetermined value and changes continuously.

(Q) The acceleration of movement of the magnetic head in the radial direction of the disk is reversed below a predetermined value and changes continuously.

In the above-mentioned equation (1), when C=0, it is a case where the track is formed by a circle.

On the other hand, in the present invention, a continuous positional variation of only C-8 in.theta. is given to the magnetic track in advance.

As a result, as shown in equation (2), the magnetic head needs to move at a continuous speed in the radial direction of the disk.

Further, as shown in equation (3), continuous acceleration in the radial direction is required. In this way, appropriate position fluctuations, moving speeds, and moving accelerations are continuously applied to the magnetic head, so there is no state in which the actuator 4 is temporarily stopped or approximately stopped, and minute positioning operations can be performed. It will repeat smoothly. Since the period of this positioning operation is 2π, it is sufficiently longer than the period of the vibration of the disk itself or the inaccuracy of the track itself, and does not have any effect on the original positioning operation that follows these positional fluctuations. .

〔Effect of the invention〕

As described above, according to the present invention, appropriate minute positional fluctuations, movement speeds, and movement accelerations are continuously and smoothly applied to the head at all times. Therefore, the probability that the actuator will be temporarily stopped or approximately stopped is extremely low. Therefore, a phenomenon in which control to move the head does not work does not occur until a force that overcomes the frictional force and viscous force generated in mechanical contact parts such as bearings and roller guides is applied.

Furthermore, when a force that overcomes the frictional force is applied, a nonlinear phenomenon in which the object suddenly moves out of control is less likely to occur. As a result, the accuracy of tracking the target track is improved, and the track width can be narrowed, which is highly effective in meeting demands for higher recording density and smaller storage devices.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the configuration of a magnetic disk device equipped with an embodiment of the device of the present invention, FIG. 2 is a diagram explaining the shape of a magnetic track used in the present invention, and FIG. 3 is a characteristic diagram thereof. be. DESCRIPTION OF SYMBOLS 1...Track, 2...Magnetic head, 3...Servo control circuit, 4...Actuator, 5...Detector, 6...Tokyo 1 eye 2 cause rod 3 section

Claims (1)

[Claims] 1. A positioning device for a magnetic disk drive that positions a magnetic head on a magnetic track on a magnetic disk using an actuator, which includes a detector that detects the rotation angle of the magnetic disk, and a detector that stores the magnetic track on the magnetic disk. a storage means for continuously outputting the radial movement speed and movement acceleration of the magnetic disk of the magnetic head at a predetermined value or less according to the rotation angle of the magnetic disk from the detector; and a target signal from the storage means. 1. A positioning device for a magnetic disk drive, comprising: and a servo control circuit that outputs an operation signal to an actuator based on a position signal of a magnetic head. 2. Claims characterized in that the magnetic track on the magnetic disk has a track shape that continuously changes the moving speed and moving acceleration of the magnetic head in the radial direction of the disk below a predetermined value. 2. The positioning device for a magnetic disk device according to claim 1. 3. The magnetic disk device according to claim 2, wherein the storage means gives the radial movement distance, radial movement speed, and movement acceleration of the disk as a trigonometric function of the angle of the magnetic disk. Positioning device.