JPS5958616A - Magnetic head - Google Patents

Abstract

PURPOSE:To lower and raise output levels of low frequency and high frequency regions respectively to improve the SN ratio, by arranging plural reading heads in the running direction of a magnetic recording medium and adding or subtracting their output signals and outputting results. CONSTITUTION:Reading heads 2a and 2b having an approximtely equal reproducing frequency characteristic are arranged a length (a) apart from each other in the running direction of an arrow A of a recording medium 3, and output signals are added or subtracted in an operating circuit 4. The length (a) is selected properly for the running speed of the recording medium to lower and raise output level of low and high frequency regions of the synthesized output, respectively, thus improving the SN ratio.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a magnetic head having a structure in which a plurality of read heads are provided close to each other and signals outputted from the respective read heads are added or subtracted.

Conventional technology Conventionally, a magnetoresistive element (hereinafter referred to as an MR element5) is
It has been used to detect magnetic fields or, more recently, as a read head in magnetic recording anglers.

However, the reproduction frequency characteristic of the MR element is, for example, a so-called low-pass characteristic in which the level of the output signal attenuates as the frequency increases, as shown in the graph of FIG.

When performing high-density recording and reproduction in a recording and reproduction system exhibiting such frequency characteristics, it is necessary to configure an equalizer adapted to the characteristics to correct the reproduction frequency characteristics.

However, configuring an equalizer has the disadvantage that the scale of the system increases.

Purpose The present invention provides a magnetic head that suppresses the output level in the low frequency range without correcting the reproduction frequency characteristics using the above-mentioned equalizer or the like, and improves the S/N ratio by increasing the output level in the high frequency range. is intended to do.

To this end, in the present invention, a plurality of read heads are arranged along the traveling direction of the recording medium, and the signals output from the plurality of read heads are added or subtracted and output.

EXAMPLES Hereinafter, the present invention will be explained in detail based on the examples shown in the drawings.

FIGS. 2(a) and 2(b) are configuration diagrams showing different embodiments of the magnetic head of the present invention. In the figure,
1 is a base, 2a and 2b are read heads using MR elements attached to both sides (Figure (a)) or one side (Figure (b)) of the base 1, and 6 is a magnetic tape, magnetic sheet, etc. The magnetic recording medium 4 is an arithmetic unit for adding or subtracting signals output from the read heads 2a and 2b.

In FIGS. 2(a) and 2(b), it is assumed that the recording medium 3 is traveling in the direction of arrow A at a speed of V''/sec.

Now, if the readout head 2a and 2b, which have substantially the same reproduction frequency characteristics, are provided on both sides or one side of the base 1, separated by a distance am, the signal output from the readout head 2b will be the same as the signal outputted from the readout head 2a. The output is delayed by one second.

Therefore, when the signals output from the read heads 2a and 2b are added or subtracted from each other, the frequency characteristics shown in the graph of FIG. 3 can be obtained depending on the frequency of the information recorded on the recording medium B. I can do it.

For example, in the part where the frequency is extremely low (the left end of the graph), the signals output from the magazine feed heads 2a and 2b are at almost the same level, so if they are added, the maximum value is characteristic 5 (broken IIM), and if they are subtracted, the signal is the minimum value. It can be seen that the value exhibits characteristic 6 (solid line).

Here, the frequency characteristic G (f) obtained by subtracting the delayed signal is G (f) = ls group (πf - u) 1 ... (1), and similarly, by addition, G (fl = 1cos(πf-,)l...(
It can be represented by one piece.

On the other hand, if the frequency characteristic of the indulgence head is H(f),
The frequency characteristic T(f) obtained by the recording/reproducing system is T(f) = Cr ffl −H(f)
...(2) becomes.

That is, T (fl has the frequency characteristic shown in FIG. 1, and G (f) has the frequency characteristic shown in characteristic 5 or B of FIG. 3.

Now, in characteristic 6 (solid line) shown in Fig. 3, v/2a
In order to set the recording medium 30 running speed to v'' 7.5 m/see, the distance between the heads shown in Figure 2 fa) and (b) is a-0.
, 675Iijn.

That is, when the distance a between the heads and the running speed V of the recording medium are set to the above-mentioned values, the output level is attenuated at low frequencies within the frequency range of 0 to 10 to 420. Therefore, characteristic 6 (Fig. 6) obtained by subtracting the output signals of the read heads 2a and 2b
If you pass a signal with a low frequency and high output level to the reproduction system as shown in Figure 1, you can obtain the characteristics shown in Figure 4 and smooth the frequency characteristics. become.

Then, the frequency band from the maximum value of the frequency characteristic called D50 to the half value of the maximum value (the value of Σ) becomes wider, and the S/N ratio is improved at high frequencies. Specifically, in Figure 6, the S/N ratio is 3d at the local wave number.
B.Improved.

In addition, the indulgence head 2 shown in Fig. 2 t8) and (b)
a.

2b is manufactured using thin film technology, and the head-to-head distance a = 0.575 μm as described above (Fig. 2(b)).
NI I? on one side of the base 1 as shown in 1. A configuration in which elements are stacked is practical.

In such a thin film laminated head, it would be possible to provide the function of the arithmetic unit 40 by connecting the NjR element portions constituting each read head section in series or in parallel. Figure 5(a),
(b) represents a circuit in which M element parts are connected in series or in parallel.

In Fig. 5(a), resistance loss R12 is an MR element, and a bias current 61t is supplied from voltage source E to resistors R1 and R2 connected in series.

Now, resistors R1 and R2 are connected to the read head 2 shown in FIG.
When information is read from the recording medium in correspondence to a and 2b, the resistance values of the resistors i(,1 and R2 change to the values of R1+ΔR+ and R2+ΔR2, respectively, in response to changes in magnetic flux.Here, R,1==R2=R,R>ΔR
Assuming 1° ΔR2, the variation ΔV in the voltage between the output terminals 7a and 7b can be expressed as Δ■=1(ΔR2−ΔR1) (6). (However, kl is a constant).

That is, if the output parts of the indulgence heads 2a and 2b shown in FIG. 2 are configured as shown in FIG. 5, it is possible to extract the output difference between the two heads, so that characteristic 6 shown in FIG. 6 can be obtained. Therefore, the output characteristics shown in FIG. 4 can be easily obtained.

Similarly, in the equivalent circuit for reduction η shown in @5 Figure 2), R12R2=TL, RL=)(,/
2, the output terminal f3a, ! The change in voltage between 3b △V is △V == &2 (△R1+△n2)
It can be expressed as @-(3)'. (however,
k2 is a constant).

In the above explanation, two reading heads are used, but the number of reading heads is two or more, the output level of each is changed, and the output signals are added. Alternatively, it is also possible to obtain the desired frequency characteristics by subtracting.

Effects As mentioned above, it is possible to reduce level changes in the reproduced frequency characteristics, widen the frequency band, and improve the S/N ratio at high frequencies. Furthermore, there is no need for additional circuits such as equalizers,
Furthermore, since the head is handled in the same way as a conventional stand-alone head, the device can be simplified and reliability can be improved.

[Brief explanation of drawings]

Fig. 1 is a graph showing the frequency characteristics of a single bladder removal head, Fig. 2 (a) and (b) are block diagrams showing different embodiments of the magnetic head of the present invention, and Fig. 3 is a graph showing the frequency characteristics of a single bladder removal head. A graph showing the frequency characteristics when added or subtracted, Figure 4 is a graph obtained by passing the characteristics shown in Figure 1 through the system of characteristics shown in Figure 3, Figure 5 (a)
, (b) is a circuit diagram of an equivalent circuit showing a subtraction circuit and an addition circuit, respectively. 1... Base 2a, 2b... Read head 6...
Recording medium 4... Arithmetic circuit frequency f (MHz)

Claims (1)

[Claims] A magnetic head characterized in that a plurality of successive heads are arranged in a running direction KG of a magnetic recording medium, and output signals of the plurality of reading heads are added or subtracted and output.