JPS639284B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic head used in a magnetic recording device to read bits recorded on a medium, and particularly to effective use of magnetic flux generated by bits of the medium.

Recently, the density of magnetic recording has been increasing more and more, and the size of the bits recorded on the medium has become smaller and smaller, and the size of the bits has reached the order of micrometers.
In such a small volume bit, the magnetic energy of the magnetic medium is very small, and the readout output is inevitably small.

However, in response to this situation, a head that utilizes the magnetoresistive effect of permalloy has been proposed as being effective in improving output.

A typical example of this is as shown in FIG. 1, in which a thin film permalloy 2 is arranged in a narrow gap 1, and a bias current conductor 3 for applying a bias magnetic field to the permalloy 2 is also arranged in close proximity. This bias is symmetrical with respect to the magnetic resistance R as shown in curve 6 shown in Figure 2, and N and S cannot be discriminated. At the same time, the aim is to increase sensitivity in areas with large gradients.

Also, sandwiching the thin film Permalloy 2 in the narrow gap 1 is necessary in order to read out local changes commensurate with the bit length, just as in a normal magnetic head, and if the thin film Permalloy 2 is placed alone, the readout bits will be difficult to read. This is because the signal is affected by all the magnetizing forces of the bits before and after it, causing the signal to become dull.

From a different perspective, it can be said that a shield 5 is applied to the bits before and after (see Figure 1).

However, this shield 5 also has the disadvantage that the magnetic flux in the intended bit portion tends to leak to the side as shown by the arrow in FIG. 3, reducing its efficiency.

The object of the present invention is to utilize the magnetic flux generated by the bits of the medium as effectively as possible, and to eliminate interference signals coming from the preceding and succeeding bits.

In the present invention, thin film magnetoresistors are formed in multiple layers with spaces between each other in a plane perpendicular to the medium running direction, signals generated by the magnetization of each of these thin film magnetoresistors are independently read out, and these read signals are weighted. A transversal filter circuit is constructed by multiplying and adding the respective coefficients through means,
This objective is achieved by a transversal type magnetic head characterized in that its output signal is used as a read signal.

The present invention will be explained in detail below.

The idea of the present invention is to provide separate detectors for detecting interference signals before and after the readout signal detector, and to remove the signals later by electrical analog calculation.

This idea has already been established as a transversal filter, and as shown in Figure 4, the transversal filter obtains the previous and subsequent signals through a time delay element 7, multiplies them by an appropriate coefficient 8, and adds them. This aims to emphasize only the correct signals.

On the magnetic recording medium p4, what corresponds to this time delay element 7 is obtained by a geometric positional shift before and after the recording bit. That is, when performing magnetic recording, if the relative velocity between the medium and the head is maintained accurately, a correct relationship can be obtained between the positional deviation of the recorded bits and the time offset.

Therefore, by adding and subtracting the outputs of the detectors placed before and after the detector using an analog electric circuit, only the main signal components can be emphasized. Naturally, the detectors placed before and after the detector include the main component and one signal component further away. To distinguish this, we need a detector further outside.

Therefore, the present invention proposes a detection method as shown in FIG. 5, in which signals from multi-stage magnetoresistive elements are simultaneously input and calculated.

FIG. 5 is a detection circuit for explaining one embodiment of the transversal magnetic head according to the present invention.

The magnetic head is made of thin film magnetoresistive elements 9, 10, 11, 1.
2 and 13 are formed in multiple layers on a surface perpendicular to the traveling direction (arrow direction) of the medium 4 with a space a between each other. Note that a conductor A for applying a bias magnetic field is also arranged.

In the relative motion between the thin film magnetoresistive resistors 9 to 13 and the medium 4, for example, when the medium 4 is moved in the direction of the arrow, the resistance value R of the thin film magnetoresistive resistors 9 to 13 changes depending on the bit of the medium 4, respectively. If the resistance element facing the target medium bit to be read is the thin film magnetoresistive element 11, the target medium bit is detected not only by the thin film magnetic resistor 11 but also by the thin film magnetic resistors 10, 1 before and after it.
2, and is further detected by the thin film magnetoresistive devices 9 and 13 before and after it, respectively. In this case, each thin film magnetoresistive 9~
Since the space a is taken for each of 13, the target signal component detected by each thin film magnetoresistive is the same as the medium 4.
By maintaining the relative velocity of the head and the head exactly, it is obtained in proportion to the space a. The obtained detection signals are multiplied by respective coefficients via the weighting means r, and input to the operational amplifier 14, where they are added and subtracted, and only the target signal component is output.

As described above, the signals obtained by each of the multi-stage magnetoresistive elements detecting the media bits are simultaneously inputted via the weighting means, and the electric circuit calculates and emphasizes only the main signal, Interfering signals coming from the bits are removed.

The present invention has been explained above with reference to the embodiments. According to the present invention, thin film magnetoresistances are formed in multiple layers with spaces between each other in a plane perpendicular to the medium running direction, and magnetization is generated by the magnetization of each of these thin film magnetoresistances. By reading each signal independently, multiplying each read signal by a coefficient, and adding them to obtain a read signal, the magnetic flux generated by the bits of the medium can be effectively used, and the magnetic flux that can remove interference signals from the previous and subsequent bits can be effectively used. The benefits that heads can provide are significant.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view for explaining a conventional magnetic head that utilizes the magnetoresistive effect, and Figures 2 and 3 are
FIG. 4 is an explanatory diagram of the transversal filter according to the present invention, and FIG. 5 is an explanatory diagram of an embodiment of the transversal type magnetic head according to the present invention. Diagram for explaining, In the diagram, 4 is the medium, 7 is the delay, 8 is the coefficient, 9 to 1
3 is a thin film magnetoresistive device, and 14 is an operational amplifier.

Claims (1)

[Claims] 1 Forming thin film magnetoresistances in multiple layers with spaces between them in a plane perpendicular to the medium running direction, reading signals generated by the magnetization of each of these thin film magnetoresistances independently, and applying weighting means to these read signals. By multiplying and adding the respective coefficients,
A transversal magnetic head comprising a transversal filter circuit and using its output signal as a read signal.