JPH0233710A - Digital multi-element magnetic head - Google Patents

Abstract

PURPOSE:To eliminate a waveform equalizing circuit, to decrease the number of parts to be used and to attain cost-reduction by arranging plural element magnetic heads in a track direction with prescribed intervals and synthesizing signals from these element magnetic heads with serial connection, parallel connection or partially coupling the serial and parallel connection. CONSTITUTION:Four element magnetic heads 1a-1d are arranged to a digital multi-element magnetic head 1 and this magnetic head 1 is moved in an arrow direction on a magnetic medium 9. The head width of these element magnetic heads 1a-1d is respectively defined as W1-W4 and a relative position in the track direction between the heads is defined an interval (s). The output signals of the respective element magnetic heads 1a-1d obtains the serial connection, parallel connection or the partial coupling of the serial and parallel connection by a synthesizing circuit 10. A bias current is supplied from a terminal 101 to the respective element magnetic heads 1a-1d and the signal is converted to a voltage signal or current signal and outputted from a terminal 102.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a digital multi-element magnetic head that is used in digital magnetic recording and reproduction, etc., and has a waveform equalization function in the head itself.

2. Description of the Related Art In recent years, devices for performing high-density digital magnetic recording, such as DAT (digital audio tape recorder), have been put into practical use. Conventional magnetic heads used in these devices have a single heald gap for 2 bays per track.

FIG. 8 shows a digital data reproducing circuit using a conventional magnetic head.
A head 5 reads out the recorded signal, amplifies it with an amplifier 2, equalizes it with a waveform equalization circuit 3, and inputs the equalized signal to a data strobe circuit 4.

In recording and reproducing such digital data, various modulation methods are used in order to make effective use of the required band and time interval accuracy, but the non-distortion condition for the reproduced waveform is given by the Nyquist standard. Therefore, a waveform equalization circuit is used to reshape the distorted output waveform read from the recording medium and reproduce digital data.

A transversal filter is a circuit often used as this waveform equalization circuit. FIG. 9 shows an example of a waveform equalization circuit using a 4-tap transversal filter.

In FIG. 9, 301 is an input terminal, 31, 32 and 33 are delay elements, 34 to 37 are coefficient circuits, 38 is an adder circuit, and 302 is an output terminal. The operation will be explained below with reference to FIG.

A signal reproduced from a recording medium and amplified to a predetermined level is input to the input terminal 301 . This signal is input to delay element 31 and sequentially input to delay elements 32 and 33. Here, if the amplitude of the input signal is A, the frequency is ω, and the delay amount of the delay element is T, then the input signal is Aexp(jω
It can be expressed as (t+3T/2)l. The output signal of each tap can be expressed as follows using this input signal.

Input of coefficient circuit 34 Aexp (jω(t+3T/2
) 1 coefficient circuit 36 input Aexp (jω(t+T
/2) Input of 1 coefficient circuit 36 Aexp (jω(t
-T/2) ) Input of coefficient circuit 37 Aexp (j
(11(t −3T/2 ) 1) Therefore, if the coefficients of each multiplier circuit are set to 1., 2., 3, and 4, the output 302 of the adder circuit 38 is A[K16xp(jω(t+3T/2)l
+2exp(jω(t+T/2)1+3eXp (
j (11(t-T/2)l+ to 4exp (j ω(
t-3T/2)l). For example, 2 = 3
If we put 4 = P K in =K and K1 =, the adder circuit 3
The output of 8 is 2 A K (CO8 (ωT/2) + P C05 (3ω
T/2))·exp(ωt), and a linear phase characteristic can be obtained.

In this way, the waveform equalization circuit was used to adjust the recording and reproducing characteristics to obtain a distortion-free condition that satisfied the Nyquist criterion.

Problems to be Solved by the Invention However, the conventional configuration described in section 2 requires a waveform equalization circuit, which increases the number of components and increases power consumption.
It had the disadvantage of being large.

Means for Solving the Problems In order to solve the above problems, the digital multi-element magnetic head of the present invention arranges a plurality of element magnetic heads at predetermined intervals in the track direction, and The apparatus is equipped with a synthesizing means for synthesizing signals by connecting signals in series, in parallel, or by partially combining series and parallel connections.

Operation With the above-described configuration, the present invention reproduces the data pattern recorded on the track of the medium with each element magnetic head arranged at a predetermined interval in the track direction, so that the relative speed between the head and the medium and the element magnetic head are arranged at predetermined intervals in the track direction. By changing the relative spacing of the magnetic heads, a predetermined time delay can be caused in the reproduction output signal of each element magnetic head, and by changing the polarity of each element magnetic head by connecting them, the magnitude of the signal from these element magnetic heads can be set in advance. A waveform equalization effect can be obtained by combining the two signals.

Embodiment FIG. 4 is a diagram showing the configuration of a digital multi-element magnetic head according to an embodiment of the present invention.
The mechanical configurations of a, 1b, 1c, and 1d are shown. Fourth
In the figure, reference numeral 9 indicates a recording track of the magnetic recording medium 2, on which the digital multi-element magnetic head 1 is moved in the direction of the arrow. Element magnetic heads 11L, 1b, 1c, which form the nod 1 to digital multi-element magnetism.
The head widths of 1 (16 base) are Wl, W2.W3.W4, respectively.

Further, the relative positions of the heads in the trunk direction are spaced apart by a distance S. FIG. 6 is a diagram showing the configuration of a digital multi-element magnetic head according to another embodiment of the present invention, and shows the arrangement of the element magnetic head in the case of having an azimuth angle.

If the relative velocity between the head and the medium is V, then a relative delay time of S/V is obtained between the heads.

If the shortest recording wavelength is λ, the shortest period Tw is Tw - λ/■
becomes. Now, if the interval S is set to 1/2 of the shortest recording wavelength λ, the delay time T is obtained as T=TW/2.

The output signals of each head, each having a delay time T, are obtained by multiplying them by a coefficient corresponding to the number of turns of the head, so by adding or subtracting and synthesizing these signals, it is possible to obtain the effect of a transversal filter.

FIG. 6 shows the electrical configuration of an example of the digital multi-element magnetic head of the present invention.

Four element magnetic heads 1a, 1b, 1C
, 1d(7) output signals are added and subtracted and synthesized in a synthesis circuit 10, and are taken out as output signals from terminals 100 and 101.

FIG. 1 is a diagram showing a composite circuit in which element magnetic heads are connected in series using a head as an element magnetic head. The output signals of the element magnetic heads are each E1! L,E
Assuming that lb, 1C, and Eld, the output signal of the digital multi-element magnetic head 1 is output between the output terminals 101 and 100, and the combined output signal E101 is as follows.

E1o1=-R1a+E1b+E1cmE1d Therefore, since the polarity can be selected, the number of turns of the element magnetic head and the different head widths as shown in FIG. 4 can be combined to easily design each tap coefficient as desired. The same effect can be produced by using a Hall effect head instead of a ring head as the element magnetic head. Since the Hall effect head is manufactured by thin film patterning technology, it is suitable for miniaturization and is relatively easy to form into a multi-element magnetic head, making it suitable for the digital multi-element magnetic head of the present invention.

FIG. 1B is a circuit diagram of a digital multi-element magnetic head according to the present invention in which a ring head or a Hall effect type head is used to form a composite circuit in which each element magnetic head is connected in parallel with selected polarity.

When using a mirror-like head, both electric and magnetic means can be used as the synthesis means, and these are particularly suitable for miniaturization.

FIG. 2 is a diagram showing an example of a digital multi-element magnetic head of the present invention using magnetic synthesis means.
a to 1d are gaps Ga in FIG.

Corresponds to Gb, Gc, and Gd. In Figure 2, the gap Ga
, Gd are connected in series, gaps Gb and Gc are connected in series, and these two series combinations are recombined in parallel to form one magnetic signal, which is converted into an electric signal by a coil and sent to terminal 101,
It is output from 100.

FIG. 3 is a diagram showing a synthetic circuit for a digital multi-element magnetic head according to the present invention when a magnetoresistive head is used as the element magnetic head. Since the magnetoresistive head is also made by thin film patterning technology, it is suitable for miniaturization, and it is relatively easy to form a multi-element magnetic head, making it suitable for the digital multi-element magnetic head of the present invention.

Since the magnetoresistive head uses resistance change, the terminal 10
Bias power supply EO is supplied from 2. Assuming that the resistance values of the element magnetic head are Ra, Rh, Rc, and Rd, the output voltage generated at the terminal 101 at this time is 101=KO・(Rb+Rc)/(RΔ+Rb+Rc
+Rd).

Partially differentiating this, θX101/δRa= -Eo Ka, (
Ra-toC1) 'θE101/θRb==Eo
Kb (Rh-+02)-2aE1o1/1tc=
Eo Kc-(Re+C3)'δE101/8Rd-
-Eo·Kd (Rd+04)-2 is obtained.

Ka, Kb, Kc, Kd and C110/, -702,03,04 in the formula are constants. As is clear from this, the element magnetic heads 11L, 1 (1 and 1b, 1c have opposite polarities of output signals with respect to resistance changes).

In this way, the polarity of the coefficient can be selected by changing the insertion position of the element magnetic head in the resistive voltage divider circuit, so that any coefficient can be set. The magnitude of the coefficient can be set by the thickness and composition of the thin film.

FIG. 3B is a diagram showing a suitable combination circuit when a magnetoresistive head is used as the element magnetic head, and is a combination of element magnetic heads connected in series or in parallel. At this time, the calculations are different, so the coefficients are different, but the operation is the same as that of the person in Figure 3.

FIG. 7 shows an example of a digital data reproducing apparatus using the digital multi-element magnetic head of the present invention.

In FIG. 7, reference numeral 1 denotes a digital multi-element magnetic head of the present invention, and a reproduced output signal is amplified by an amplifier 2 and applied to a data strobe circuit 4. Data strobe circuit 4
extracts the clock from the self-clocking signal and reproduces the data. A phase-locked loop circuit is used to extract the error.

Even when the output signal of the digital multi-element magnetic head is taken out via a rotary transformer in FIG. 7, the signals are synthesized in advance in the digital multi-element magnetic head of the present invention, so a rotary transformer is connected to each node of each magnetic element. This has the effect of being able to transmit data using a single rotary transformer without the need for preparation.

As is clear from FIG. 7, the waveform equalization circuit that was conventionally required can be omitted.

Note that the number of turns and the spacing S of each element magnetic head are determined based on constants obtained by designing the transversal filter.

Further, in this embodiment, the distance S is set to be the same value between each element magnetic head, but the distance S may be set to be different between each element magnetic head.

Furthermore, in this embodiment, the number of element magnetic heads is four, but any integer greater than or equal to two may be used, and as with the number of taps of the transversal filter, this is left to the degree of freedom in the design. It's not even worth mentioning.

Effects of the Invention As described above, according to the present invention, the data pattern recorded on the track of the medium is reproduced by each element magnetic head arranged at a predetermined interval in the track direction, so that the head and the medium are A predetermined time delay can be caused in the reproduced output signal of each element magnetic head by the relative speed of the element magnetic heads and the relative spacing of the element magnetic heads, and the polarity can be changed by connecting the signals from these element magnetic heads in series or parallel. By combining the same signals, the magnitude of the output signal can be set in advance and a waveform equalization effect can be obtained. Therefore, a waveform equalization effect with linear phase characteristics can be obtained with a single head, and a distortion-free condition that satisfies the Nyquist criterion can be achieved. Therefore, it is possible to eliminate the waveform equalization circuit that was conventionally necessary, and it is possible to reduce costs by reducing the number of parts, reduce power consumption, and downsize.

[Brief explanation of the drawing]

FIG. 1 is a wiring diagram showing a circuit for synthesizing reproduction output signals of a digital multi-element magnetic head according to an embodiment of the present invention, and FIG. 2 is a structural diagram of a digital multi-element magnetic head using a synthesis means using a magnetic circuit. , FIG. 3 is a wiring diagram of a composite circuit of a magnetoresistive head according to this embodiment, FIGS. 4 and 6 are element magnetic head arrangement diagrams of a digital multi-element magnetic head according to an embodiment of the present invention, and FIG. is a signal connection diagram of the digital multi-element magnetic head, FIG. 7 is a block diagram of a digital data reproducing apparatus using the digital multi-element magnetic head of the present invention, and FIG. 8 is a diagram of digital data reproducing using a conventional magnetic head. FIG. 9 is a block diagram of a waveform equalization circuit used in a conventional digital data reproducing apparatus using a magnetic head. DESCRIPTION OF SYMBOLS 1...Head, 1a, 1b, 1c, 1a-Element magnetic head, 10...Composition circuit, 2.Amplifier, 3
... Waveform equalization circuit, 4 ... Data strobe circuit, 9 ... Magnetic medium, 31, 32.33 ...
-Delay element, 34.35.36.37...-coefficient circuit, 38...addition circuit. Name of agent: Patent attorney Shigetaka Awano and 1 other person”

Claims (1)

[Claims] It has a plurality of element magnetic heads, the element magnetic heads are arranged at predetermined intervals in the track direction, and the signals of these element magnetic heads are connected in series, connected in parallel, or partially combined with series and parallel connections. A digital multi-element magnetic head characterized by being equipped with a means for synthesizing.