JPS60150222A - Thin film magnetic head - Google Patents

Abstract

PURPOSE:To enable use of a magnetic tape deposited of metal by evaporation and to increase the S/N of reproduced output by coupling electrically the 3rd electrode means and 2nd conductive thin film of a magneto-resistance effect element by conductive thin film lead wires using a photolithography means for each of tracks. CONSTITUTION:An MRE15 has the 3rd electrode (e) at approximately the center thereof. The MRE15 and a common earth wire 13 are coupled by means of a lead wire 18 consisting of the same material as the material of lead wires 16, 17. The lead wire 18 connected to the central electrode (e) of the MRE15 is on the 2nd insulating layer 14 and the connection to the wire 13 is accomplished easily by a window part (f) formed when the 2nd insulating layer 14 on the common earth wire is etched. The window parts opened on both sides of the wire 18 are back gap parts (b) which are the part for coupling the upper magnetic layer and a ferromagnetic substrate 10. The MRE15, the lead wires 16, 17, 18 and further the 3rd insulating layer 19 of SiO or SiO2, etc. as the insulating layer for the wire 13 are formed by vapor deposition, sputtering, etc.

Description

[Detailed Description of the Invention] Industrial Field of Application The present invention is directed to magnetic recording devices using magnetic tapes and magnetic disks, as demands for higher recording density, higher reliability, lower cost, etc. Instead of heads made from bulk materials, thin-film creation technology and photolithography technology are used to create narrow gaps.

The present invention relates to a thin film magnetic head that achieves narrow tracks, multi-tracks, and fulfills the above requirements.

Conventional configurations and their problems Recently, magnetoresistive elements (hereinafter referred to as MREs) have been used as playback heads in magnetic recording devices due to shorter track widths and slower magnetic tape running speeds due to improved track density. The magnetoresistive head (hereinafter referred to as MR head) used is becoming widely used. A typical structure thereof is shown in FIG.

In FIG. 1, a ferromagnetic substrate, for example Mn-Zn.

A first insulating layer 2 such as 5i02 is laminated on a ferrite substrate 1 such as Ni-Zn by sputtering, a Ni-Fe film as an MRE is formed thereon, and a photolithography technique is applied so that it is in contact with the magnetic tape 9. patterned by. Thereafter, a second insulating layer 4 of SiO, 5in2, etc. is formed by vapor deposition, sputtering, or the like. After forming a ferromagnetic thin film such as a Ni-Fe film 6 on this second insulating layer 4 by electron beam gluing or sputtering,
A protective layer 6 such as the following is laminated by vapor deposition, sputtering, or the like. After that, use adhesive 7 etc. to protect the protective substrate 8 made of glass or ceramic.
is glued. After the above steps, the tape sliding surface of the head is wrapped and completed.

However, this conventional magnetic head has the following drawbacks.

(1) MRE requires a sense current to flow in order to extract playback output, but in recent years, metal-deposited magnetic tapes for high-density recording have been developed, and the recording magnetic layer of these metal-deposited tapes has electrical conductivity. Therefore, the sense current that should be passed through the MRK flows into the tape magnetic layer. This not only makes it impossible to obtain a satisfactory reproduction output as an MR head, but also makes a multi-track structure essentially impossible.

(The first insulating layer 2 and the second insulating layer 4 must be formed on both sides of the MRE 3 in FIG. 1.
For the magnetic gap length in the head, if the film thicknesses of the first insulating layer 2 and the second insulating layer 4 are made equal, this film thickness becomes the equivalent gap length. However, if the thicknesses of the insulating layers 2 and 4 are different, a double-gap behavior is exhibited.

(3) If the current method is applied as a means of applying a magnetic bias to the MRIC 3 in Figure 1, it is necessary to form a bias line with the same width as the MRK in the lower or upper layer of the MRE, and the gap length is equal to the thickness of the bias line. spreads out, which is extremely inconvenient when reproducing short wavelength signals.

(4) Since the tip of the MRE 3 is exposed at the tip of the head and is constantly in contact with the tape surface during playback, there are problems with the abrasion resistance of MREs and durability due to ambient environmental conditions.

(@ As a solution to the problem (1) above, there is a configuration in which the MRIC 3 is placed deep from the tip of the head, but in this system, the MR head has a space between the magnetic tape 9 and the magnetic tape 9 by the recess amount of the MRE 3. This is equivalent to the occurrence of pacing, and causes a large attenuation of the short wavelength reproduction output.

Purpose of the Invention The present invention aims to increase the track density to narrow the track, and to increase the frequency characteristic band to narrow the gap, thereby achieving high density recording and high reliability in magnetic tapes and magnetic recording devices. The objects of the present invention, which relate to thin film multi-track magnetic heads, and in particular as compared to conventional Ml'l heads, are as follows.

(1) Enables the use of metal-deposited magnetic tape and increases the S/N of reproduction output.

(2) It is possible to detect the amount of off-track between the recording track and the reproduction track so that each track of the reproduction head can faithfully on-track on the recording track pattern, and it can also be applied to track servo.

(3) Optimize the conductive thin film pattern of each track to reduce the probability of occurrence of problems such as poor insulation and improve yield.

Structure of the Invention The magnetic circuit structure in each track of the present invention is such that the ferromagnetic substrate is used as the lower magnetic layer, and the ferromagnetic thin film acting as the upper magnetic layer is divided into a front magnetic layer and a rear magnetic layer. to form an MRE.

For example, the magnetic flux flowing into the upper magnetic layer from the recorded magnetic tape flows in series from the front magnetic layer → MRK → rear magnetic layer, and falls to the ferromagnetic substrate, which is the lower magnetic layer, at the pack gap, and finally becomes magnetic. It is based on a magnetic circuit configuration that returns to the tape. Furthermore, the characteristic configuration of the present invention is as follows.

(1) The MRE of each track is provided with three electrode terminals at both ends in the track width direction and at approximately the center thereof.

(11) One common bias line for each drag located directly below the MRH is arranged in each MRE, and one common ground line is formed on the same plane parallel to this common bias line. This common ground line and the intermediate electrode terminal of each MRH are electrically connected. That is, approximately the center of the MRE is at ground potential. The common ground line is located outside the closed magnetic circuit formed by the upper magnetic layer and the ferromagnetic substrate and is formed at a position close to the pack gap.

-011) As a method of providing a sense current to each MRIC, positive and negative reverse polarity voltages having approximately the same absolute value are applied to the electrode terminals at both ends of the MRR, respectively, and constant current driving is achieved.

The resistance change of the MRlE due to the signal magnetic field from the magnetic tape is output as a voltage change by connecting the electrode terminals at both ends of the MRE to a differential amplifier circuit.

Furthermore, as an additional configuration, at least one track or more of MR
It is also possible to apply voltages of the same polarity having substantially the same absolute value to the electrode terminals at both ends of the MRE, and the electrode terminals at both ends of the MRE are connected to a differential amplifier circuit.

Gv) A groove extending in the track width direction filled with an insulating material and having a width of at least the shortest distance connecting the front gap depth of the ferromagnetic substrate and the pack gap portion is formed on the ferromagnetic substrate surface.

Description of examples An embodiment of the present invention will be described below with reference to the drawings.

FIG. 2 is a plan view of the thin film multi-track magnetic head of the present invention, and FIG. 3 is a cross-sectional view taken along the line X--X. A first insulating layer 11, for example SiO2, is formed on the entire surface of the ferromagnetic substrate 10 by sputtering on a ferromagnetic substrate 10, for example a Mn--Zn single crystal ferrite substrate, and the front gap length is controlled by the thickness of this film. On the same plane on this first insulating layer 11, a first conductive thin film 12 for a common bias and a second conductive thin film 13 for a common ground line are formed parallel to the track width direction by vapor deposition and photolithography techniques. It is formed. These conductive thin films 12 and 13 are formed by the same process, and the material used is crT base material such as MuU or Mufuji. In order to form an insulating layer on the conductive thin film 12.13, a second insulating layer 14 such as 8i02 is laminated by sputtering or the like. The tip of the common ground wire (not shown) is etched away. This second insulating layer 1
4 on the common bias line 12 with approximately the same width,
A number of MREs 15 corresponding to the number of traps are formed at a desired track pitch interval by vapor deposition, sputtering, etc. 11 .

After that, it is patterned. MRI! :16 has sense current supply electrodes c and d at both ends, and each has a mn
, Lead wires 16° 17 made of Au with an Or base are connected. In addition, there is a third
Ml'1E15 and the common ground wire 13 are connected by a lead wire 18 made of the same material as the lead wires 16 and 17. This situation is shown in the perspective view of FIG. In FIG. 4, the central electrode e of MRKl 5
The lead wire 18 to be connected to is on the second insulating layer 14, and the connection with the common ground line 13 is easily made through the window f formed by etching the second insulating layer 14 on the common ground line. . The windows opened on both sides of the lead wire 18 in FIG. 4 are the pack gap portions, which are the bonding portions between the upper magnetic layer and the ferromagnetic substrate 10.

A third insulating layer 19 of SiO, 5i02, etc. is formed by vapor deposition, sputtering, etc. as an insulating layer for the MREls, lead wires 16, 17.1B, and common ground wire 13. The insulating layer 19 is removed from the leading ends (not shown) of the lead wires 16, 17, the common bias wire 12, the common ground wire 13 on the substrate 1o, and the back gap portion 1. After this, the ferromagnetic thin film layer as the upper magnetic layer is made of, for example, Ni-Fe.
The film is formed of an Fe-based R-8t film, and a front magnetic layer 20 and a rear magnetic layer 21 are formed by etching. 22 in FIG. 3 is a magnetic tape, and B is the tape running direction. Further, in the present invention, a groove-shaped portion 23 is formed in the ferrite substrate 10 and filled with an insulating material such as glass for the purpose of improving the magnetic circuit efficiency. Due to the design of the magnetic circuit consisting of the upper magnetic layer, lower magnetic layer, and MFIE, the element width of the MRE, that is, the width in the direction perpendicular to the track width direction, is approximately 10μ.
m or more, the glass-filled groove portion 23 becomes an effective means for improving magnetic efficiency to prevent magnetic flux leakage between the MRK and the lower magnetic layer. A groove depth of 16 μm or more is sufficient.

FIG. 6 shows a model example of a method for driving the MRK15 and the common bias line 12. For example, each MRE is connected so that the sense current XS flows in the direction of arrow 39.
A positive voltage is applied to the external supply terminals 13 and 32 connected to the external supply terminals 13 and 32, and a negative voltage is applied to the other supply terminals 33, and the current of the circuit 8 is made constant by the high resistance elements 34 and 35. At this time, a positive voltage is applied to the bias current supply terminal 3o and a negative voltage is applied to the other terminal 31 of the common bias line 12 so that the bias current Xb flows in the same direction as the sense current Is, as indicated by the arrow 38. The output of each MRIC is taken out from the output terminal 37 of the MR and H terminals connected to a differential amplifier 36.

The feature of the present invention is to control the recording track and the reproduction track so that each track of the magnetic head can faithfully on-track the recording pattern. This is possible by switching the current driving direction to the MRIC of at least one track among the multi-tracks of the reproducing head. For example, the external supply terminals 40 and 41 of the sense current circuit for the MRK shown in FIG. 5 are switched to track control, and the situation is shown in FIG. 6. In FIG. 6, external supply terminal 40
．． 41 are applied with voltages of the same polarity having substantially the same absolute value.

Ib is applied to the common bias line 12 in the same manner as shown in FIG. For example, if a positive voltage is applied to terminals 40 and 41, MRI! :Sense current I8 flowing through 15
are in opposite directions with respect to the ground wire 13. In the above state, a recording pattern 46 (width W) is recorded on the magnetic tape 22 moving in the running direction C by the track control recording head 44. At this time, if an off-track amount P occurs between the recording head and the reproducing head, the track control MRE 16
An output voltage corresponding to the recording signal 45 is generated at the differential amplifier output 43 of. If the off-track amount is zero, no output is generated at the output terminal 43. Depending on the output from the output terminal 43, the position of the recording head including the track 46 or the entire reproducing head including the track control MRE in the track width direction can be adjusted to accurately align the two tracks.

Effect of the invention According to the present invention explained above, the following effects can be obtained.

- It is possible to provide a narrow gap, narrow track magnetic head that can use metal-deposited tape, and is particularly effective in short wavelength reproduction, and can achieve high-band reproduction characteristics.

■ By differentially outputting the MRE, it is possible to remove in-phase component disturbances and reduce noise, and it is also possible to improve magnetic efficiency by machining grooves on the ferrite substrate, making it possible to create a high S/N head. can be provided.

■ The common ground wire can be installed near Mfll, eliminating problems in the thin film process caused by lead wires connecting the common ground wire and MRE, and can be patterned on the same plane as the common bias wire. It is possible to simplify the manufacturing process.

■ It is possible to match recording tracks and playback trunks very precisely.

(2) By appropriately selecting the material for the upper magnetic layer, it is possible to provide a thin film head with excellent wear resistance and durability.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a conventional magnetoresistive head, FIG. 2 is a plan view of a multi-track 5-track magnetoresistive head showing an embodiment of the present invention, and FIG. 3 is a sectional view of the same. Figure 4 is a perspective view at an intermediate stage of the thin film process, Figure 5 is a circuit diagram showing the head, drive to the common bias line, and reproduction output, and Figure 6 is a perspective view showing the off-track detection configuration. . 1o...Ferromagnetic substrate, 11...First insulating layer, 12...First conductive thin film, 13...
...Second conductive thin film (ground wire), 14...
...Second insulating layer, 16...Magnetoresistive element, c, d...Sense current supply electrode, e...
...Third electrode. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2 Figure 5 Figure 6

Claims (1)

[Claims] (1) A first insulating layer is formed on a ferromagnetic substrate, and a first conductive layer for common bias is formed on the insulating layer in a strip-like manner sequentially on the same plane deep from the magnetic gap. A thin film and a second conductive thin film for a common ground line are arranged parallel to each other in the track width direction, and a first conductive film corresponding to the number of tracks is placed on the first conductive thin film via a second insulating layer. A magnetoresistive element having approximately the same width as the thin film is disposed, and a pair of first . a ferromagnetic thin film layer having a second electrode means and a third electrode means approximately at the center thereof, and divided into a front part and a rear part at approximately the center above each magnetoresistive element via a third insulating layer; The front ferromagnetic layer forms a magnetoresistive element. A magnetic closed circuit is constituted by the rear ferromagnetic layer and the ferromagnetic substrate in this order, and the second, seventh and third electrode means of the magnetoresistive element and the second conductive thin film are connected to a conductive thin film lead wire. A thin-film magnetic head characterized in that each track is electrically coupled using a shift odrinography method. (Rumor) Claim 1 characterized in that the second conductive thin film for the common ground wire is formed at a position deeper than the pack gap and close to the pack gap when viewed from the tape sliding surface. (3) The track width of at least one track in the multi-track is equal to or larger than the recording track width, and the first and second electrode terminals of the magnetoresistive element of the track are absolutely connected by electric circuit means. 2. The thin film magnetic head according to claim 1, wherein the recording track signal can be read by applying voltages of the same polarity having substantially equal values. The thin-film magnetic head according to claim 1, characterized in that positive and negative opposite polarity voltages having substantially equal absolute values are applied to the two electrode terminals by electric circuit means, respectively. Claim 1 or 4 is characterized in that the direction of the sense current flowing in the magnetoresistive element and the direction of the bias current flowing in the first conductive thin film for common bias are made to coincide with each other. A thin-film magnetic head. (→ A groove-shaped portion having at least the shortest distance width connecting the front gap depth and back gap portion of the ferromagnetic substrate is formed on the upper surface of the ferromagnetic substrate, and a non-magnetic and insulating material is formed in the groove-shaped portion. 2. The thin film magnetic head according to claim 1, wherein the thin film magnetic head is filled with a magnetic substance.