JPS641849B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a thin film reproducing head for magnetic recording, which is easy to narrow the track and is less affected by magnetic flux leakage (crossfeed) from the recording head.

In order to make magnetic recording devices smaller and larger in capacity,
It is desired to improve recording density. In order to achieve this, research has recently begun on thin film porcelain heads that can easily be made into narrower tracks, and have begun to be put into practical use. Among thin-film read heads, heads that utilize the magnetoresistive effect have significantly better read sensitivity than heads that use electromagnetic induction. By the way, in general, in magnetic recording devices, in order to increase the reliability of written information, a so-called read-after-write check is generally performed in which read information is checked in parallel with writing. Further, in some cases, a recorder is required to have a function of monitoring the reproduced sound in parallel with recording. In these devices that perform reproduction at the same time as recording, so-called cross-feed noise, which is caused by the reproduction head sensing magnetic flux leakage from a recording head placed near the reproduction head, becomes a problem.

FIG. 1 shows the main parts of a conventional thin film reproducing head that utilizes the magnetoresistive effect, and here shows a structure corresponding to one track on a recording medium (not shown). 1 is a magnetoresistive element made of a rectangular magnetic thin film; 2 is a left-hand conductor; 3 is a right-hand conductor; 4
is a central conducting wire portion, and each of the conducting wire portions 2, 3, and 4 is arranged in parallel so as to have one end in contact with each end and the center portion of the magnetoresistive element 1 and extend in orthogonal directions. 5
is the direction of the sense current. This head is equipped with a magnetoresistive element 1 for the purpose of reducing external noise picked up by the connection line connecting the head and the differential amplifier (not shown).
In addition to the left conductor part 2 connected to one end of the right conductor part 2 and the right conductor part 3 connected to the other end of the
A central conducting wire portion 4 connected to the central portion is arranged. That is, a sense current is passed in one direction 5 of the magnetoresistive element 1, and the left conductor part 2 and the right conductor part 3 are connected to the input terminal of the differential amplifier,
By connecting the central conducting wire section 4 to the ground terminal of the differential amplifier, external noise becomes a common-mode input, and therefore is not amplified by the differential amplifier, but is canceled out.
However, the direction of the leakage magnetic flux from the recording head passing inside the loop composed of the left conductor part 2, the magnetoresistive element 1, and the center conductor part 4, Since the direction of leakage magnetic flux from the recording head passing inside the loop formed by the right conductor part 3 is the same (from the front to the back or from the back to the front in the drawing), the left conductor part 2 and the center conductor part 4 The crossfeed noise induced between the right conductor section 3 and the center conductor section 4 is in opposite phase.
Therefore, since the cross-feed noise is differentially amplified in the same way as the reproduced signal, the cross-feed noise is so large that it cannot be put to practical use.

Furthermore, in a shield type thin film reproducing head in which one or both sides of the magnetoresistive element 1 is covered with a magnetic material and provided with a magnetic shield in order to improve the reproducing resolution, leakage magnetic flux from the recording head is concentrated on the shielding magnetic material. However, crossfeed noise was a more serious problem.

Note that the sense current direction 5 shown in FIG.
This is a case of a type in which a unidirectional bias magnetic field is applied to the entire magnetoresistive element 1. There is also a type in which the direction of the bias magnetic field is reversed with the center of the magnetoresistive element 1 as the border, but the only difference is that the sense current flows in the opposite direction with the center of the magnetoresistive element 1 as the border. , the above description is the same.

In view of these drawbacks, the present invention provides a
In a thin film reproducing head that reproduces the recorded contents of a track, a pair of magnetoresistive elements made of a rectangular magnetic thin film are placed on the longitudinal extension line of each other such that one end side faces each other with a predetermined interval. A plurality of conducting wire portions are arranged in parallel such that one end thereof is in contact with each end of each of the magnetoresistive elements and extends in orthogonal directions, and located at the end of the same side of each of the magnetoresistive elements. Connecting only a pair of conducting wire portions to each other at a predetermined distance from each magnetoresistive element,
This is connected to the ground terminal of the differential amplifier, and another pair of conductive wire portions located at the ends of the other same side of each of the magnetoresistive elements are connected to the input terminal of the differential amplifier, and By applying a bias magnetic field to each of the magnetoresistive elements in the same direction and causing the sense current to flow in the opposite direction, or by applying a bias magnetic field in the opposite direction and causing the sense current to flow in the same direction, crossfeed noise is significantly reduced. The drawings will be described in detail below.

FIG. 2 shows an embodiment of the thin film reproducing head of the present invention, and here, like the conventional example, a configuration corresponding to one track on a recording medium is shown. In the figure, 1
Reference numerals 0 and 11 designate a pair of magnetoresistive elements each made of a rectangular magnetic thin film, which are arranged in parallel on an extended line in the longitudinal direction of each other such that one end portions 10a and 11b face each other with a predetermined distance therebetween. 12 is a first right conductor part, 13 is a second right conductor part, 14 is a first left conductor part, 15 is a second left conductor part, and each conductor part 12, 13, 14, 15 is a first right conductor part. Corresponding ends 10 of the first and second magnetoresistive elements 10 and 11
a, 11a, 10b, 11b and are arranged in parallel so as to extend in the orthogonal direction, and the first right conductor part 12 and the second right conductor part 13 are connected to the first magnetoresistive element 10 and the second magnetoresistive element 10. magnetoresistive element 1
It is connected at a predetermined distance from 1. One direction 16 of the first magnetoresistive element 10 and the second direction 16 of the first magnetoresistive element 10
A sense current is passed in the opposite direction 17 of the magnetoresistive element 11, and the first left conductor part 14 and the second left conductor part 15 are connected to the input terminal of a differential amplifier (not shown). The right conductor portion 18 is used by being connected to the ground terminal of the differential amplifier.

In the head of the present invention, as described above, the direction of the sense current is reversed between the first magnetoresistive element 10 and the second magnetoresistive element 11, so that after connection with the first left conductor part 14, The reproduction signal generated between the right conductor portion 18 and the reproduction signal generated between the second left conductor portion 15 and the right conductor portion 18 after connection are in opposite phase. On the other hand, the direction of the leakage magnetic flux from the recording head passing inside the loop constituted by the first left conductor section 14, the first magnetoresistive element 10, and the first right conductor section 12, left side conductor part 15,
The direction of leakage magnetic flux from the recording head passing through the inside of the loop formed by the second magnetoresistive element 11 and the second right conductor 13 is the same (from the front to the back of the drawing, or from the back to the front). ) Therefore, the first
The crossfeed noise induced between the second left conductor portion 14 and the connected right conductor portion 18 and the crossfeed noise induced between the second left conductor portion 15 and the connected right conductor portion 18 are in phase. Therefore, although the reproduced signal is differentially amplified, the crossfeed noise is canceled out.

The above effect can be obtained in the same way even if the relationship between the left conductor part and the right conductor part is reversed, or even if the directions of the sense currents flowing through the two magnetoresistive elements are reversed. Furthermore, the same effect can be obtained even with a shield type magnetoresistive head in which one or both sides of the magnetoresistive element is covered with a magnetic material and provided with a magnetic shield.

Note that the direction of the sense current shown in FIG.
This is a case where a bias magnetic field is applied in the same direction to two magnetoresistive elements. Regarding the type in which opposite bias magnetic fields are applied to two magnetoresistive elements, the above explanation is the same, except that the sense current flowing through one of the magnetoresistive elements is reversed. .

As explained above, according to the present invention, in a thin film reproducing head that reproduces recorded content for one track on a recording medium, a pair of magnetoresistive elements made of a rectangular magnetic thin film are attached to one end of the thin film reproducing head. A plurality of conducting wire portions are arranged in parallel on an extension line in the longitudinal direction of each other so that the sides face each other at a predetermined interval, one end is in contact with each end of each of the magnetoresistive elements, and a plurality of conducting wire portions are arranged in parallel so as to extend in orthogonal directions. , only a pair of conductive wire portions located at ends on the same side of each magnetoresistive element are connected to each other at a predetermined distance from each magnetoresistive element, and this is connected to a ground terminal of a differential amplifier. Further, another pair of conductive wire portions located at the ends of the other same side of each of the magnetoresistive elements are connected to the input terminal of the differential amplifier, and the same bias magnetic field is applied to each of the magnetoresistive elements. Since the bias magnetic field is applied in the opposite direction and the sense current is made to flow in the opposite direction, or the bias magnetic field is applied in the opposite direction and the sense current is made to flow in the same direction, crossfeed noise can be significantly reduced without affecting the reproduced signal in any way. This has the advantage that accurate and faithful reproduction can be performed even when used in a magnetic recording device that requires recording and reproduction at the same time.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the main part of a conventional thin film reproducing head using the magnetoresistive effect, and FIG. 2 is a diagram showing the main part of a thin film reproducing head according to the present invention. 10, 11... Magnetoresistive element, 12, 1
3, 14, 15...Conducting wire section.

Claims (1)

[Claims] 1. In a thin-film reproducing head that reproduces the recorded content of one track on a recording medium, a pair of magnetoresistive elements made of rectangular magnetic thin films are arranged so that the end sides of one of them face each other with a predetermined distance between them. A plurality of conducting wire portions are arranged in parallel on an extension line in the longitudinal direction, one end is in contact with each end of each of the magnetoresistive elements, and a plurality of conducting wire portions are arranged in parallel so as to extend in an orthogonal direction, and on the same side of each of the magnetoresistive elements. Connect only the pair of conducting wire portions located at the ends of each of the magnetoresistive elements at a predetermined distance from each other, and connect this to the ground terminal of the differential amplifier. Another pair of conductor wires located at the ends on the same side are connected to the input terminal of the differential amplifier, and a bias magnetic field is applied to each of the magnetoresistive elements in the same direction, and a sense current is applied in the opposite direction. 1. A thin film reproducing head characterized in that a sense current is applied in opposite directions and a sense current is caused to flow in the same direction.