JPS6013322A - Tracking control device of magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To control a magnetic head on a recording track by fitting the 1st and 2nd magnetically sensitive elements to a recording or reproducing magnetic head so as to be symmetrized about the longitudinal center line of the recording track each other. CONSTITUTION:When the magnetic head is positioned on the center of the recording track, i.e. when a main magnetic pole 2a and a sub-magnetic pole 2b are tracked precisely by the recording track 1b, the magnetically sensitive elements 4, 5 are arranged on completely symmetrical positions about the center line O of the recording track 1b and outputs obtained from the respective magnetic poles are completely symmetrical. If the magnetic head is shifted from the recording track 1b, a difference between the outputs of the magnetically sensitive elements 4, 5 is generated. Consequently, a signal corresponding to the difference is outputted from a differential element 7, a servo motor 6 is controlled through an amplifier 8 and the magnetic head 2 is moved to the center position of the recording track 1b.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a magnetic recording and reproducing apparatus that uses a magnetic head to record or reproduce information signals on recording tracks on a magnetic information medium such as a magnetic disk, which has a simple configuration and is sufficiently accurate. The object of the present invention is to provide a tracking control device that positions a magnetic head on a recording track.

The configuration thereof will be described below based on drawings of embodiments. FIG. 1 is a partial plan view of a magnetic disk, which is an example of a magnetic information medium 1. A disk-shaped magnetic disk is provided with a disk body la made of synthetic resin or the like, and a recording track 1b made of a magnetic material continuously formed in a spiral shape on the disk body la, and the track width T and pitch of the recording track 1b are P is about 1 to several microns.

FIG. 2 is a sectional view showing the magnetic head 2 for recording or reproducing information signals on the recording track 1b of the magnetic disk 1. As shown in FIG.

A main magnetic pole 2a of the magnetic head 2 is in contact with the upper surface of the magnetic disk 1, and a sub magnetic pole 2b is disposed at a certain distance from the lower surface of the magnetic disk 1, facing the main magnetic pole 2a. A coil 3 is wound around the sub magnetic pole 2b, and when an information signal is input to this coil 3, the recording track 1b is
The magnetic material is magnetized in a direction perpendicular to the surface of the magnetic disk 1, and information is recorded on the recording track 1b by rotation of the magnetic disk 1. Information is reproduced from the recording track 1b by rotating the magnetic disk 1 and reading changes in the magnetic flux between the main magnetic pole 2a and the sub-magnetic pole 2b of the magnetic head 2 as changes in the current generated in the coil 3.

FIG. 3 shows the main part of the embodiment of the present invention, and is a view of the recording track 1b and the magnetic head 2 seen from above.

The main magnetic pole 2a has approximately the same width as the width T of the recording track 1b.
A pair of magnetic sensing elements 4 and 5 for tracking so that the magnetic head 2 including the magnetic head always accurately tracks the recording track lb.
is installed. As the magnetic sensing element, a magnetoresistive element (MR element), a Hall element, etc. are suitable, and its shape is rectangular in cross section like the main magnetic pole 2a. and the first
゜The 20th magnetic sensing elements 4 and 5 have exactly the same shape and are arranged symmetrically with respect to the longitudinal center line O of the recording track 1b with an interval g, and the main magnetic pole 2a is located on the recording track 1b. , the center of each magnetic sensing element 4, 5 is located near the side edge of the recording track 1b.

Tracking control by the magnetic sensing elements 4 and 5 is performed as follows.

First, the magnetic head 2 moves to the recording track 1b as shown in FIG.
In other words, when the main magnetic pole 2a and the sub magnetic pole 2
b is accurately tracked with respect to the recording track 1b, the first magnetically sensitive element 4 and the second magnetically sensitive element 5.
Since they are located at completely symmetrical positions with respect to the center line O of the melt recording track 1b, the outputs obtained from each are also exactly the same. However, as shown in FIG. 4, when the magnetic head 2 is shifted upward (or downward) with respect to the recording track 1b, the first magnetic sensing element 4 becomes further away from the recording track 1b and moves away from the second magnetic head.
The magnetically sensitive element 5 approaches the recording track 1b. Therefore, the first. A difference occurs between the outputs of the second magnetic sensing elements 4 and 5.

Figure 5 is 1. A control circuit for driving the servo motor 6 of the magnetic head 2 with the outputs from the second magnetic sensing elements 4 and 5 is shown, and as described above, the first. When a difference occurs in the outputs of the second magneto-sensitive element 4.5, a signal corresponding to the difference is output from the differential element 7.
The servo motor 6 is controlled via the amplifier 8 to move the magnetic head 2 to the center position of the recording track 1b.

In order to easily perform such control, the first . It is desirable that the dimensions of the second magnetic sensing element 4°5 satisfy the following formula.

That is, 1st. The width of the second magnetic sensing elements 4 and 5 is It-4, respectively.
If the distance between the two magnetic sensing elements 4 and 5 is g, then T-g≦2. +2° However, lz = It e T > g As a result, the first. When the second magnetic sensing elements 4 and 5 are sufficiently tracked, they are always on the recording track 1b.

FIG. 6 shows another embodiment of the present invention, in which the first and second
The magnetic sensing elements 4 and 5 are attached to different sides of the main magnetic pole 2a. In this embodiment as well, the recording track 1b
Since the distances of the 1st and 20th magnetic sensing elements 4 and 5 with respect to the center line 0 are the same, it is possible to obtain the same tracking control signal as in the first embodiment.

Although the above embodiment shows a perpendicular magnetic recording/reproducing device, the present invention is not limited thereto, and can be applied to a magnetic disk,
It is clear that the present invention can be widely applied to devices that form recording tracks of a fixed width on a magnetic information medium such as a magnetic tape or reproduce information from these recording tracks.

The present invention is as described above, and in a magnetic recording and reproducing apparatus that records or reproduces a magnetic signal on a recording track on a magnetic information medium, with respect to the longitudinal center line of the recording track,
The first and second magnetically sensitive elements are attached to a recording or reproducing magnetic head so as to be symmetrical to each other, and the first and second magnetically sensitive elements are attached to the magnetic head for recording or reproducing. The present invention is characterized in that the magnetic head for recording or reproduction is controlled on the recording track by the differential output of the second magneto-sensitive element.

Therefore, it is possible to reliably control the tracking of the magnetic head with a simple structure, and because the first and second magnetic sensing elements are simply attached symmetrically to the magnetic head for recording and reproducing, It is easy to manufacture and can be provided at low cost.

[Brief explanation of drawings]

FIG. 1 is a plan view showing a part of the magnetic information medium, FIG. 2 is a sectional view showing the relationship between the magnetic information medium and the magnetic head, and FIG. FIG. 4 is a plan view showing the magnetic head deviated from the recording track, FIG. 5 is a tracking control circuit that drives a servo motor, and FIG. The figure is a plan view showing the relationship between a magnetic head and a recording track in another embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Magnetic information medium, 1b... Recording track, 2... Magnetic head, 4... First magnetic sensing element, 5... ...Second magnetic sensing element, 0...
...The longitudinal center line of the recording track. 131-

Claims (1)

[Claims] In a magnetic recording/reproducing apparatus that records or reproduces magnetic signals on a recording track on a magnetic information medium, a first...
A second magnetically sensitive element is attached to a recording or reproducing magnetic head, and the first magnetically sensitive element is attached to a recording or reproducing magnetic head. A tracking control device that controls the recording or reproducing magnetic head on a recording track using a differential output of a second magnetically sensitive element.