JPH06295408A - Production of magnetic head - Google Patents

Abstract

PURPOSE:To provide the magnetic head free from variations in frequencies by mounting a mounting pedestal on a core holder for die casting having high dimensional accuracy, then mounting a shielding case thereon and polishing the tape-sliding surface of this case. CONSTITUTION:The magnetic head is produced by first forming the magnetic cores 9, 10 in a known manner and has coil terminal parts 11, 12 and 13, 14. The magnetic cores 9, 10 are assembled to the core holder 15 consisting of zinc die casting of a nonmagnetic material having an electrical conductivity. The holder 15 has fitting grooves 16, 17 and 18, 19 for fitting to the cores 9, 10 and core holders 20, 21 and is formed with the high dimensional accuracy. The mounting pedestal 22 made of zinc die casting is then mounted on the holder 15. This mounting operation is carried out by mounting the pedestal 22 on one flank of the holder 16 by an adhesive with the base 15a of the holder 15 as a reference plane A, by which the degradation in functions by heat is prevented. The holder 15 is then assembled to the shielding case 29 consisting of 'Permalloy(R)' and an epoxy resin is packed therein. The reference plane A and the sliding surface 33 are finished to regulated sizes by grinding.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a magnetic head mounted on a video tape recorder (VTR) or the like.

[0002]

2. Description of the Related Art For example, as a magnetic head for a video tape recorder, a shield case 101 made of permalloy or the like as shown in FIGS. 6 and 7 has a pair of magnetic cores 102, 103 forming a closed magnetic path. The stored one is proposed.

In the magnetic head having such a structure, a pair of cores made of an oxide magnetic material such as ferrite is butted against each other through a gap film to form magnetic gaps g ₁ and g ₂ at the butted surfaces. Magnetic core 102,
A core holder 1 composed of 103 and a pair of core retainers 104 and 105 for holding the magnetic cores 102 and 103.
06 and the magnetic cores 102 and 103 incorporated in the core holder 106 are housed inside, and the magnetic core 10
The shield case 101 is made of permalloy and has core fitting holes 107 and 108 for exposing the magnetic gaps g ₁ and g ₃ of ₂ , 103 to the outside.

The magnetic cores 102 and 103 are fitted in the notches cut in the core retainers 104 and 105, respectively, and are retained by the core retainers 104 and 105. Then, the magnetic core 102 held by these core pressers 104, 105,
103 is housed together with a grounding spring in a shield case 101 having a bottomed casing having an opening on one side, and is fixed by an epoxy resin injected from the back side of the shield case 101.

[0005]

By the way, in the magnetic head having the above-mentioned structure, a mounting pedestal 109 is provided on one side surface of the shield case 101 in order to fix the magnetic head at a predetermined position of the video tape recorder. It is designed to be fixed to the device side with bolts and the like. In this magnetic head, the mounting base 10 in FIG.
The distance a from the center of the mounting hole 110 provided on the upper side of 9 to the tape sliding surface 111 of the shield case 101 is very important.

That is, the fact that the dimension a changes is that the amount of protrusion of the head with respect to the magnetic tape changes, which causes variations in frequency.
Therefore, it is necessary to attach the mounting pedestal 109 to the shield case 101 so that the a dimension becomes a predetermined value.

Two methods have been used so far to attach the mounting pedestal 109 to the shield case 101. One method is to fix the mounting pedestal 109 to one side surface of the shield case 101 by spot welding or the like with reference to the back surface 101a of the shield case 101 in advance as shown in FIG. And the core holder 1
After the magnetic cores 102 and 103 incorporated in 06 are assembled in the shield case 101, as shown in FIG. 7, the tape sliding surface 111 on which the magnetic tape of the shield case 101 slidably contacts is ground into an arc shape.

Another method is, as shown in FIG. 9, the magnetic cores 102 and 103 assembled to the core holder 106.
Is incorporated into the shield case 101, and the tape sliding surface 111 of the shield case 101 is polished. Then, as shown in FIG. 10, the mounting pedestal 109 is fixed to one side surface of the shield case 101 by spot welding or the like with reference to the tape sliding surface 111.

The former method uses the shield case 101 in advance.
On the other hand, after mounting the mounting pedestal 109, the internal structure is assembled and finally polished. However, the variation in each process is integrated, and the shield case 101, which is a press-molded component, is used as a reference. To
It is difficult to maintain the accuracy of the reference itself, and the positional accuracy of the mounting base 109 deteriorates.

The latter method uses the tape sliding surface 111 after completion of the magnetic head as a reference, so that it is easy to secure the required accuracy, but the internal structural material is incorporated into the shield case 101 and the mounting pedestal 109 is installed. Since the assembling is divided into two parts, equipment such as a spot welding machine is required, and there is a high possibility that the function of the head will be impaired by heat during welding. Further, since the surface is assembled on the outer circumference of the shield case 101, it is difficult to keep the strength stable.

Therefore, the present invention has been proposed in view of such circumstances, and it is a method of manufacturing a magnetic head in which the mounting position of the mounting pedestal with respect to the tape sliding surface is not highly precise and the strength is satisfactory. The purpose is to provide.

[0012]

DISCLOSURE OF THE INVENTION The present invention has been proposed in order to achieve the above-mentioned object, and after attaching a mounting base to a core holder incorporating a magnetic core forming a closed magnetic circuit, The core holder is assembled to the shield case, and then the tape sliding surface of the shield case which is in sliding contact with the magnetic recording medium is polished.

[0013]

In the method of the present invention, the mounting pedestal is not mounted on the shield case, but is mounted on a core holder having a magnetic core incorporated therein and having high dimensional accuracy. Therefore, the mounting position of the mounting pedestal on the tape sliding surface is high. It will be accurate.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Specific embodiments of a magnetic head manufacturing method to which the present invention is applied will now be described in detail with reference to the drawings. In order to manufacture a magnetic head, first, as shown in FIG. 1, coil bobbins 3 and 4 each having a predetermined number of windings 1 and 2 wound on a pair of cores 5 made of ferrite and having a substantially U shape in plan view. , 6 and 7, 8 are incorporated to form magnetic cores 9, 10 forming a closed magnetic circuit.

These magnetic cores 9 and 10 are a pair of cores 5 and 6 which are respectively inserted into the coil bobbins 3 and 4 from the left and right.
And 7 and 8 are abutted inside and outside the coil bobbins 3 and 4 and are magnetically coupled to each other to form a closed magnetic circuit, and the magnetic gaps g ₁ and g are formed by sandwiching the gap film formed on the abutting surface. _Make up _two .

The coil bobbins 3 and 4 are integrally formed of a resin material having an insulating property, and both ends of the windings 1 and 2 wound around the coil bobbins 3 and 4 are twisted to serve as terminals. It has coil terminal binding parts 11, 12 and 13, 14 for.

Next, the assembled magnetic cores 9 and 10 are
As shown in FIG. 2, it is assembled to a core holder 15 made of zinc die-cast or the like which is a non-magnetic material having conductivity. As shown in FIG. 1, the core holder 15 has a pair of fitting grooves 16, 17 and 18, 19 for fitting the cores 5, 6 and 7, 8 protruding from the coil bobbins 3, 4 therein. It is composed of core retainers 20 and 21.
Fitting groove 1 provided in each of the core retainers 20 and 21
By fitting the cores 5, 6 and 7, 8 to 6, 17, 18 and 19, respectively, the pair of magnetic cores 9 and 10 assembled in the previous step are inserted into the core retainers 15 and 16 described above.
Is gripped by.

Next, a mounting base 22 for fixing the magnetic head at a predetermined position of the video tape recorder is attached to the core holder 15. As shown in FIG. 3, the mounting pedestal 22 is formed as a rectangular block by zinc die casting or the like like the core holder 15. The mounting base 22 is provided with head fixing mounting holes 23 and 24 which penetrate in the thickness direction and are vertically provided at predetermined intervals. Further, when the magnetic cores 9 and 10 are assembled in the shield case 29 in the next step, the mounting pedestal 22 is
Guide grooves 27, 28 into which the pair of leg portions 25, 26 are fitted are formed on one side surface of the shield case 29.

When the mounting pedestal 22 is attached to the core holder 15, the bottom surface 15a of the core holder 15 which is the reference surface for polishing is used as the reference surface A, and the mounting pedestal 2 is attached.
2 is attached to one side of the core holder 15 with an adhesive. Since the attachment pedestal 22 is attached to the core holder 15 not by spot welding but by an adhesive agent, equipment such as a welding machine is not necessary and the function of the head is not deteriorated by heat. Further, since both the mounting base 22 and the core holder 15 are made of die-cast products having high dimensional accuracy, the mounting base 22 can be mounted on the core holder 15 with high accuracy.

Next, the core holder 15 to which the mounting pedestal 22 is attached is attached to the magnetic gaps g ₁ and g in a shield case 29 made of a permalloy in the form of a casing having one bottomed bottom. Install with ₂ as the insertion direction. When the core holder 15 is assembled in the shield case 29, the magnetic cores 9 and 10 are contacted between the other side surface of the core holder 15 and the inner wall surface of the shield case 29 so that the magnetic cores 9 and 10 do not rattle against the shield case 29. As described above, the earth spring 30 for urging the core holder 15 toward the shield case 29 is assembled together. In addition, the earth spring 30 connects the core holder 15 to the shield case 2
In addition to the role of elastically biasing to 9, the core holder 15 and the shield case 29 also have a function of grounding.

Then, the guide grooves 27, 2 of the mounting base 22
Using the legs 25 and 26 of the shield case 29 that engage with the shield guide 8 as guides, the core holder 15 is used as the shield case 2.
It is inserted in 9. The magnetic gaps g ₁ and g ₂ present on the head sliding surfaces of the magnetic cores 9 and 10 are located outside the core fitting holes 31 and 32 formed in the bottom surface of the shield case 29 and having a rectangular shape in plan view. To face.

The shielding case 29 is mounted on the upper side of the mounting pedestal 22 shown in FIG. 4 because the mounting pedestal 22 is mounted on the magnetic cores 9 and 10 with high precision in advance. The distance a from the center of the mounting hole 23 to the tape sliding surface 33 of the shield case 29 (the required dimension for determining the amount of head protrusion) is the minimum necessary to allow the polishing allowance regardless of what. In FIG. 4, b indicates the distance from the bottom surface of the shield case 29 to the bottom surface of the core holder 15, and c indicates the polishing size. Further, since the mounting pedestal 22 is assembled to the core holder 15, it is possible to obtain one having sufficient strength.

Next, in order to fix these parts and eliminate the influence of humidity, an epoxy resin (not shown) is heated and filled in the shield case 29. The epoxy resin penetrates into the gaps between the respective parts and securely fixes the respective parts such as the magnetic cores 9 and 10 incorporated in the shield case 29. Finally, the tape sliding surface 33, which is the bottom surface of the shield case 29 where the magnetic gaps g ₁ and g ₂ face, is ground into an arc shape so that the a dimension becomes a predetermined value.

As a result, a highly reliable magnetic head in which the mounting position of the mounting base 22 with respect to the tape sliding surface 33 is controlled with high precision is manufactured.

The specific embodiments to which the present invention is applied have been described above, but the present invention is not limited to the above-described embodiments, and various modifications can be made. For example, in the previous example, the mounting pedestal 22 was attached to the core holder 15 with an adhesive. However, as shown in FIG. 5, the core holder 15 is provided with a protrusion 34 having a substantially T-shaped plane, and the protrusion 34 is fitted to the protrusion 34. The fitting groove 35 may be provided in the mounting base 22. That is, by fitting the mounting base 22 to the core holder 15 and assembling it, the assembling work can be simplified.

In this case, the shield case 29
The mounting pedestal 22 is also housed inside together with the core holder 15, and the circular holes 36 and 37 for exposing the head fixing mounting holes 23 and 24 provided on the mounting pedestal 22 on the side surface of the shield case 29. To provide.

With such a structure, like the magnetic head of the previous embodiment, a highly reliable magnetic head in which the mounting position of the mounting pedestal 22 with respect to the head sliding surface 33 is controlled with high precision can be obtained. it can. Therefore, the positional accuracy of the mounting pedestal 22 with respect to the tape sliding surface 33 can be secured, the mounting on the set can be simplified, and the strength can be sufficiently secured, and the reliability can be greatly improved.

[0028]

As is apparent from the above description, according to the present invention, after attaching the mounting base to the core holder made of die-casting or the like having high dimensional accuracy by adhesion or fitting, the shield case is assembled, Since the tape sliding surface of the shield case is polished, it does not require equipment such as a spot welding machine and does not impair the function of the head due to heat, and mounts the mounting base on the head sliding surface. The position can be easily made highly precise. Therefore, even when the magnetic head is attached to the video tape recorder, the protrusion amount of the head with respect to the magnetic tape can be maintained at a predetermined value, and a highly reliable magnetic head with no frequency variation can be provided.

Further, according to the present invention, the yield of the head can be greatly improved by improving the assembling accuracy, and the mounting method in the set size can be simplified by reducing the variation in the accuracy of the head.

[Brief description of drawings]

FIG. 1 is a disassembled perspective view showing a magnetic core forming step, showing a step of sequentially producing a magnetic head of the present embodiment.

FIG. 2 is a perspective view showing a step of sequentially forming the magnetic heads of the present embodiment and showing a step of incorporating a magnetic core in a core holder.

FIG. 3 is a perspective view showing a step of sequentially forming the magnetic head of the present embodiment and showing a step of assembling the magnetic core in a shield case.

FIG. 4 is a side view showing a step of sequentially forming the magnetic head of the present embodiment, in which a step of polishing the tape sliding surface of the shield case is partially broken.

FIG. 5 is an exploded perspective view showing a magnetic head of another embodiment.

FIG. 6 is an exploded perspective view showing a step of sequentially manufacturing magnetic heads by a conventional method and showing a step of assembling a magnetic core in a shield case to which a mounting base is attached in advance.

FIG. 7 is a perspective view showing a step of sequentially manufacturing magnetic heads by a conventional method and showing a step of polishing a tape sliding surface of a shield case.

FIG. 8 is a side view partially showing a step of polishing a tape sliding surface of a shield case, showing a step of sequentially manufacturing magnetic heads by a conventional method.

FIG. 9 is a perspective view showing a step of sequentially manufacturing magnetic heads by a conventional method, showing a step of attaching a mounting base to a shield case after assembling the magnetic head body.

FIG. 10 is a side view showing a step of sequentially manufacturing magnetic heads by a conventional method, showing a step of polishing a tape sliding surface of a shield case.

[Explanation of symbols]

 1, 2 ... Winding 3, 4 ... Coil bobbin 5, 6, 7, 8 ... Core 9, 10 ... Magnetic core 15 ... Core holder 20, 21 ... Core holder 22 ... ..Mounting base 29 ... Shield case 30 ... Earth spring

Claims (1)

[Claims] 1. A tape sliding surface for mounting a mounting base on a core holder incorporating a magnetic core forming a closed magnetic circuit, and then assembling the core holder to a shield case, and then slidingly contacting a magnetic recording medium of the shield case. A method of manufacturing a magnetic head, comprising: