JPH0395708A - Magnetic head - Google Patents

Abstract

PURPOSE:To always obtain a stable head reproducing output without generating a step difference between cores even when the wearing of a head is advanced by obtaining a laminated structure with wearing resistance which becomes larger as a layer closes to the sliding surface of a tape in a magnetic gap depth direction for both the center cores and side cores of a part where the magnetic tape slids. CONSTITUTION:For the core of the part where the magnetic tape slids, namely, both non-magnetic side cores 21 and 22 and center cores 1 and 2 forming a magnetic path composed of a ferro-magnetic substance, the constitution is laminated in the depth direction of a magnetic gap 11. For the materials of the cores, compounds are used with the wearing resistance which goes to larger as the layer closes to a tape sliding surface 2b and a thin film is formed by laminating a vacuum thin film forming material in multiple layers to be the compound which is easily worn out toward low layer side. Accordingly, even when the wearing of the head is advanced, the spacing amount on the magnetic gap 11 maintains a minimum state for a long time. Thus, after the magnetic head is used for a long time, the reproducing output of the head can be prevented from being degraded by the physical gap to be generated between the magnetic gap and the peripheral non-magnetic part by wearing.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic head used in magnetic recording and reproducing devices such as video tape recorders (▼TR) and digital audio tape recorders (DAT).

[Conventional technology]

FIG. 14 is a perspective view of an example of a conventional magnetic head. This magnetic hend recognition is achieved by using a vacuum thin film forming technique such as sputtering to form a ferromagnetic metal thin film 2 (hereinafter referred to as the front core) on the upper surface 1a of the ferromagnetic oxide 1 (hereinafter referred to as the rear core). Magnetic core halves 9 and 10 ′5: Non-magnetic material 8 that guards the magnetic gap U
After the glass 6 is melted and then solidified, the bonding temperature is also σ). Tracks 41! are formed near the surface where the magnetic gap 11 is formed, that is, on both sides of the magnetic gap l1 on the tape sliding surface 2b. A first groove (track width regulating groove) 3 is formed for regulating i(TV), thereby concentrating magnetic flux in the gap 11. The tape sliding surface 2b has eight shapes with the magnetic gap 11 as the apex. The material of the rear core 1 is, for example, a ferromagnetic oxide such as Mn-Zn7 ferrite or Ni-Zn ferrite. The front core 2 is made of Fe-Ga-81 thread alloy, Fe-
▲It is a crystalline magnetic alloy such as l-81 thread alloy (referred to as Sendust) or an amorphous alloy such as Oo-Nb-Zr thread alloy, and has a laminated film structure. Each layer of the film is not of the same composition, but has a different composition.
This conventional product is characterized by the fact that the WI is removed. That is, the layer closer to the tape sliding surface 2b has a composition with excellent wear resistance, and the further away from the sliding surface 2b the composition is more likely to wear out.

Next, the effect will be explained. Figures 16 and 17 are...
A conventional magnetic head ratio is attached to the rotating drum 14, and a magnetic tape 15 is placed on the tape sliding surface 2 for recording and reproduction.
FIG. 3 is a schematic plan view showing a state in which the first
FIG. 6 shows the initial state, and FIG. 17 shows the state where head wear has progressed after running for a long time. In the initial state shown in FIG. 16, the protruding amount h of the head from the rotating drum 14 is large, and in addition, the tape sliding surface 2b has an 8-shaped shape, so the contact area with the magnetic tape is small. , the contact pressure between the magnetic tape and the tape sliding surface 2b is increased.

Therefore, the condition is such that it is easy to wear out. However, at this point, j! on the tape sliding surface 2b! The ferromagnetic metal thin film rod layer (front core) 2 is made of a material that is hard to wear, so the slope of the time force of the amount of wear, that is, the wear rate, is lower than that of the conventional method. It functions to be more suppressed than previous magnetic heads.

When wear progresses from this state and reaches the state shown in Figure 17,
Since the protrusion th becomes smaller and the contact area between the tape sliding surface 2b and the magnetic tape 15 becomes larger, the contact pressure becomes smaller and wear is less likely to occur. However, at this point, the stack of ferromagnetic metal thin films exposed on the tape sliding surface 2b (
Since the front core (2) is composed of a composition that is easily worn, the wear rate becomes faster than that of the conventional front core. At this point, the magnetic head shown in FIG. 14 has changed as shown in the perspective view of FIG. 15. The curve 18b in FIG. 18 represents the above-mentioned change in wear amount over time. A song that expresses the passage of time for magnetic heads before this conventional example! Compared to 18a,
Even though the total JII wear amount after long-term running is almost the same, the wear rate is kept almost constant. Therefore, even after long-term use, the cleaning effect due to head abrasion is the same as in the initial stage, and no nonmagnetic degraded layer is generated on the tape sliding surface 2b.

[Problem to be solved by the invention]

The conventional M-Ki Hendo Minoru had the following problems.
That is, FIGS. 19 to 21 are cross-sectional views of the vicinity of the tape sliding surface 2b in the thickness direction of the core when the magnetic head is viewed from a plane parallel to the magnetic gap U. The glass 6 surface and the front core 2 form a substantially continuous curved surface, and the magnetic tape and the magnetic gap 11 are in contact with each other. However, as wear progresses, the front core 2 and the glass 6 Due to the difference in the amount of wear due to the difference in the material of As a result, the head reproduction voltage decreases due to spacing loss. FIG. 20 shows a case where the magnetic thin film in the vicinity exposed to the tape slaughtering surface 2b of the front core 2 is more easily worn than the glass 6;
On the contrary, the figure shows a case where the glass 6 has a composition that is more easily worn than the magnetic thin film. In any case, since the composition of the glass 6 is uniform in the gap depth direction, no matter how the composition of the glass 6 is selected, as wear progresses, it will reach the state shown in either FIG. 20 or FIG. 21. It becomes every.

The present invention was made to solve the above-mentioned problems.
It is an object of the present invention to provide a magnetic head that can prevent a phenomenon in which the reproduction output of the head deteriorates due to the occurrence of a physical step between a magnetic gap part and a non-corrosive part around the magnetic gap part.

[Means to solve the problem]

In the magnetic head according to the present invention, the core on which the magnetic tape slides, that is, the non-magnetic side core and the center core formed of a ferromagnetic material and forming a magnetic path are both laminated in the depth direction of the magnetic gap. The tape has a structure in which the layers closer to the sliding surface of the tape are made of a material with a more wear-resistant composition, and the lower the layer, the more easily abraded the thin film is, formed by stacking multiple layers using vacuum thin film formation technology. It is.

[Effect]

In the magnetic head of the present invention, during the process in which the head surface wears out during use, the wear rate of the center core having a magnetic gap and the side cores located on both sides of the center core is almost the same, so the tape sliding surface The upper σ center core and side cores are always on almost the same curved surface. Therefore, even if head wear progresses, the amount of spacing on the magnetic gap remains at a minimum for a long period of time.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. Fig. 1 is a perspective view of a magnetic head according to the present invention.

This magnetic head has a ferromagnetic metal thin film 2 (hereinafter referred to as the front core) formed on the upper surface of a ferromagnetic oxide 1 (hereinafter referred to as the rear core) using a vacuum thin film forming technique such as sputtering. After integrating 2 and 2, the center core is cut to a width equivalent to the track width to form a magnetic path, and then both sides of this center core are joined with side cores η to form an integrated magnetic core half*. #l is joined by a non-magnetic material 8 that spans a magnetic gap U. The configuration and characteristics of the center core addition are the same as those of the conventional example, so a description thereof will be omitted. The side core d has a non-magnetic substrate 21 (
A non-magnetic laminate 22 (hereinafter referred to as the front core) is formed on the upper surface of the front core using a vacuum thin film forming technique such as vapor deposition and sputtering. Each layer of the front core laminate is The present invention is characterized by the fact that they are not of the same composition but are composed of different sets. That is, the closer the tape is to the sliding surface 2b, the more excellent the composition is in abrasion resistance, and the further away from the sliding surface 2b, the more likely the composition is to wear. Materials for the front core include OaTio, NiTi Mno% Oo
Non-magnetic ceramics such as TiMno are suitable. Since the rear core 2l does not come into contact with the magnetic tape, there is no need to use a special material as long as it is non-magnetic.

Next, the effect will be explained. FIG. 2 is a sectional view of the vicinity of the tape sliding surface 2b in the thickness direction of the core, when a magnetic head according to an embodiment of the present invention is viewed from a plane parallel to the magnetic gap 11. The magnetic tape 15 comes into contact with the magnetic tape in the state shown in FIG. 2, and wear progresses as the magnetic tape 15 travels over time. Here, both the front core 2 and the front core n have a structure in which the wear resistance gradually changes for each layer, so the front core 2 and the front core n in the portion exposed to the tape sliding surface 2b The wear rate of steel is always approximately the same over time. Therefore, there is no step caused by the difference in the amount of wear between the front core 2 and the glass 6, which was the case in the conventional example, and the amount of spacing between the magnetic tape and the magnetic gap 11 is always maintained at a minimum, so the head reproduction output voltage is kept constant as shown by line m in FIG. Also, as shown in Figure 2, when viewed in the core thickness direction, the closer to the outer surface of the core a layer with a composition that is more likely to wear out appears on the tape sliding surface 2bGI:N, so the radius of curvature r in the core thickness direction is remains small.

This produces the effect of ensuring that the magnetic gap (2) is always at the top and in contact with the magnetic tape 15.

Next, the manufacturing process of the magnetic head shown in FIG. 1 will be explained based on FIGS. 4 to 18. First, as shown in Figure 4,
A rectangular parallelepiped rear core l is formed by cutting a material made of ferromagnetic oxide. Next, as shown in FIG. 5, a laminate 2 (front core) of ferromagnetic metal thin films is formed on the upper surface l& of the rear core 1 using a vacuum thin film forming method such as buffing.

The front core 2 is laminated so that the lower the layer, the more easily worn the composition becomes. Next, as shown in FIG. 6, the nonmagnetic bulk material is cut to form a rectangular parallelepiped nonmagnetic substrate 21 (rear side core). Next, as shown in FIG. 7, a nonmagnetic thin film laminate 22 (front core) is formed on the upper surface 21 of the rear core by using a vacuum thin film forming method such as sputtering. Like the front core 2, this front side core n is also stacked so that the lower layer is more likely to wear out. Next, it is cut along the cutting line shown in FIG. 7 to divide it into individual side cores η.

The combined product of the front core 2 and rear core 1 shown in FIG. 5 is cut along the cutting line 2j to divide it into individual center cores.

Next, as shown in FIG. 8, several pieces of the center core and side cores d are joined together using glass welding or an adhesive to form a core block as shown in FIG. 9. Next, a winding groove 7 is formed in at least one of the pair of core blocks in a direction that separates the center core and the side core d,
Form the core block legs. Next, as shown in Fig. 11, the abutment surface 23a of the core block* and the abutment surface of the core block pattern are processed (V:
After that, a film of non-magnetic material 8, which will become a gap spacer, is formed between the abutting surfaces and the islands by means of vapor deposition, sputtering, etc. The sum of the thicknesses of the nonmagnetic materials is approximately equal to the width of the magnetic gap 11. Next, as shown in FIG. 12, the core block swamp and paulownia are matched. At this time, align the center cores so that they overlap each other. After that, the blocks B and U are fixed in abutted state and joined by glass welding or adhesive. Next, the upper surfaces of the front core 2 and front core of the joined core blocks are ground to form a cylindrical surface whose apex is near where the non-magnetic material 8 is filled. The surface formed in this step becomes the tape sliding surface 2b. Thereafter, the joined core blocks are cut to form individual magnetic heads 5 as shown in FIG.

In order to make the bond between the left and right cores stronger than in the above embodiment, a groove 5 passing through the rear core 1 and the rear side core 21 is provided, and glass 6 is filled in the groove 5 to form a magnetic gap. The glass 6 may be purchased as shown in FIG. 21 in which the glass 6 is melted and solidified in step 11 (formation σ).

〔Effect of the invention〕

As described above, according to the present invention, both the center core that forms a magnetic path and the non-magnetic side cores that sandwich the center core include the core of the portion on which the magnetic tape of the magnetic head slides.
The layered structure has a different composition for each layer so that the layer closer to the sliding surface of the tape in the direction of the magnetic gap depth has a composition that is more wear resistant, so even if the head wear has progressed, the center core remains intact. There is no step between the side core and the side core.
A stable head playback output is always obtained. Furthermore, since the magnetic gap portion of the center core is always worn to the top, there is an effect that a stable contact state between the magnetic tape and the magnetic gap can be obtained.

[Brief explanation of drawings]

FIG. 1 is a perspective view of a magnetic head according to an embodiment of the present invention;
2 is a cross-sectional view showing the state in which the magnetic head in FIG. 1 is in contact with a magnetic tape; FIG. 8 is a graph showing changes over time in the output voltage of the magnetic head in FIG. 1 and the conventional σJ magnetic head; 4 to 18 are perspective views for illustrating the manufacturing process of the magnetic head according to one embodiment of the present invention shown in FIG.
4 and 15 are perspective views showing examples of conventional magnetic heads, FIGS. 16 and 17 are schematic plan views showing the conventional magnetic heads attached to a rotary drum, and FIG. 18 is a conventional magnetic head. Figures 19 to 21 are cross-sectional views showing a conventional magnetic head in contact with a magnetic tape, and Figure 22 is a graph showing the wear characteristics of a magnetic head according to another embodiment of the present invention. FIG. In the figure, 1 is a ferromagnetic oxide (rear core), 2 is an FvI layer of ferromagnetic metal thin film (front core), 7 is a winding groove, 8 is a non-magnetic material, 1l is a magnetic gap, and 2b is a table. sliding surface, 21
The symbol indicates a non-magnetic substrate (rear core), and the symbol indicates a non-magnetic laminate (front core). In the figures, the same reference numerals indicate the same or equivalent parts.

Claims (1)

[Claims] A laminate of ferromagnetic metal thin films is formed on the upper surface of the ferromagnetic oxide block, and the composition of each ferromagnetic metal thin film layer is changed so that the composition becomes more wear-resistant toward the upper layer. A block consisting of an object block and the ferromagnetic metal thin film laminate is cut into a width corresponding to the track width to form a center core, and the nonmagnetic laminate is placed on each nonmagnetic thin film layer on the top surface of the nonmagnetic substrate. The non-magnetic substrate is formed by changing the composition so that it becomes more wear-resistant as it reaches the upper layer, and the non-magnetic substrate is formed by cutting a block made of the non-magnetic laminate into an appropriate width to form a side core. A pair of core blocks formed by joining both sides of the core with the side cores sandwiched therebetween, and cutting off one or both sides of the opposite sides at appropriate places to form a winding window, and using the pair of core blocks as a non-magnetic material that acts as a magnetic gap. The surface of the ferromagnetic metal thin film laminate having a magnetic gap and the upper surface of the non-magnetic laminate continuous to this surface are formed into a curved shape, and the curved surface is formed by sliding a magnetic tape. A magnetic head characterized in that it is configured to have a flat surface.