JPS6316011Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic head, and particularly to an audio magnetic head built into a video tape recorder or the like.

An example of this type of magnetic head is shown in Figures 1 and 2.
The outline will be explained with reference to the drawings. FIG. 1 is a perspective view schematically showing the ferrite core assembly of the magnetic head with the metal case removed;
The figure is a perspective view of a metal case that constitutes the outer shell of the magnetic head. This conventional example is a magnetic head having a pair of magnetic ferrite cores 1 and 2.
A and 2a are the front parts of the ferrite core, and 1b and 2b are the rear parts thereof. Spacers 4, 5, 6 made of, for example, magnetic ferrite are fixed to both side surfaces of the ferrite core front parts 1a, 2a by glass welding. A coil 8 is wound around the rear portions 1b and 2b of the ferrite core. Such a ferrite core assembly is housed in a metal case 3 made of permalloy or the like as shown in FIG. 2, and the bottom thereof is hardened with resin together with the terminals of the coil 8 (not shown) to form a magnetic head. Ferrite core front part 1a,
2a and a portion of the spacers 4, 5, 6 are exposed through the opening 7 of the case front portion 3a. In this case, if the ferrite core and metal case are in direct contact at the head front part, the magnetic flux flowing through the ferrite core will also flow toward the metal case.
A closed magnetic path consisting of the front and rear parts of the core is no longer formed. For this reason, a dummy block made of a non-magnetic material is often installed between the front part of the ferrite core and the metal case, and a magnetically resistant part of a certain thickness is formed between the blocks. When used as an audio head of a video tape recorder, for example, the spacer 4 corresponds to the image signal portion of the magnetic tape, and the ferrite core front portions 1a and 2a correspond to the audio control signal portion of the magnetic tape.

In a magnetic head with such a configuration, if the ferrite core is electrically floating from the metal case, noise is likely to be picked up during audio playback, and static electricity is generated due to friction when the magnetic tape is running. If it is not grounded, it will cause noise during playback.

Conventionally, in order to eliminate such inconveniences, the rear part of the ferrite core is held by a suitable metal plate, and the metal plate and the metal case are connected with a conductive wire and soldered. Alternatively, a method has been proposed in which the rear part of the ferrite core is pressed and held against the inner surface of the metal case by a suitable leaf spring, and grounding is established via this leaf spring. However, the former soldering method requires complicated manual work, and also requires the dimensions of the metal case itself or the back plate (bottom plate) of the metal case to absorb variations in soldering position, amount of solder, etc. It is necessary to allow sufficient space in the dimensions of the terminal holes drilled in the plate, and the molding resin may penetrate into the vicinity of the front part of the ferrite core through this gap, causing poor sensitivity. In addition, the latter method of positioning and grounding the core with a leaf spring has some problems with the material of the leaf spring, and when the metal case is fixed during grinding of the front part of the head, external force is applied to the case, causing deformation. As a result, the leaf spring is also deformed and does not return to its original state when the external force is removed, resulting in a gap between the metal case and the leaf spring, resulting in poor ground contact.

The purpose of the present invention is to provide a magnetic head that eliminates such problems, eliminates the need for soldering for grounding, leaf springs, etc., and further improves workability in manufacturing the head. It is something.

For this purpose, the present invention fixes spacers to both sides of the front part of the ferrite core, and provides flat sloped surfaces on both shoulders of the front part of the ferrite core so that the front part of the core as a whole becomes tapered. A dummy block made of a non-magnetic metal material is adhered to the entire area of this inclined surface with a conductive adhesive to form a head front part, and a dummy block made of a non-magnetic metal material is bonded to the entire area of this inclined surface, and a dummy block made of a non-magnetic metal material is bonded to the entire area of the slope between the head front part and the front part of the metal case. The magnetic head is constructed by bonding with a conductive adhesive.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 3 is a perspective view of the magnetic head according to the embodiment of the present invention, viewed from the front side. Non-magnetic metal dummy blocks 9, 10, such as brass, are adhered to the shoulders of the ferrite core front parts 1a, 2a with a conductive adhesive, and ferrite cores 9, 10 are bonded to the shoulders of the ferrite core front parts 1a, 2a using a conductive adhesive. Magnetic ferrite spacers 4, 5, and 6 are bonded to both sides of the core front portions 1a and 2a by glass welding. A metal case 3 having an opening at the front as shown in FIG. 2 is placed over this ferrite core assembly, and the inner surface around the opening of the metal case and the front part of the ferrite core assembly, that is, the head front part are connected. , and is glued around its entire circumference with conductive adhesive. Static electricity generated in the ferrite core is released to the metal case 3 via the conductive adhesive and the metal dummy blocks 9 and 10. In this way, the conductive adhesive serves both to fix the ferrite core assembly to the metal case and to provide grounding, so there is no need for soldering or positioning using leaf springs as in the past. The ferrite core can be fixed to the rear part of the ferrite core by molded resin, and the dimensions of the case back plate on which the terminal pins are erected can be made to exactly match the inner surface of the metal case. In addition, since a non-magnetic metal dummy block is pre-attached to the shoulder of the front part of the ferrite core, when gluing the spacers 4, 5, and 6 to both sides of the front part of the ferrite core, the adhesive will be applied to the shoulder of the front part of the ferrite core. The ferrite core does not adhere directly to the metal case, and can be assembled into a metal case while maintaining the shape of the ferrite core with high precision.

Next, the manufacturing process of the ferrite core used in the present invention will be briefly explained with reference to FIGS. 4a and 4b, FIGS. 5 and 6. It has an accurate shoulder shape and wall thickness as shown in Figure 4a, and a gap 12 in the center of the front.
A ferrite core material 11 having a shape is formed into a horizontally long shape,
Further, as shown in FIG. 4b, a dummy block material 13 made of a non-magnetic metal material and having the same width as the shoulder portion of the core is prepared. Magnetic head dummy blocks 9 and 10
The part shown in Figure 3 is a part where the magnetic tape does not come in contact with the magnetic tape as it runs, so there is no need to consider wear resistance, and it may be processed into a plate shape as shown in Figure 4b, or it can be processed into a plate shape as shown in Figure 4b. Select a material with good workability when slicing or grinding the core material. This dummy block material 13 is attached to both shoulders 1 of the front part of the ferrite core material 11 as shown in
1a with a conductive adhesive, thereby protecting the front part of the ferrite core material during head manufacture. Next, this ferrite core material is sliced in the horizontal direction to a predetermined thickness to obtain a ferrite core 1 as shown in FIG. Thereafter, as explained in FIG. 1, a spacer is bonded to the front part of the pair of ferrite cores 1, and the spacer is ground together with the spacer as shown by the broken line in FIG. FIG. 7 is a partial side sectional view of the magnetic head obtained as described above. In this figure, reference numeral 12 indicates the gap, and reference numeral 14 indicates the polished surface of the front portion of the head that was polished after the gap 12 had been positioned and adjusted. 15 is a conductive adhesive;
Grounding is established through this adhesive. As will be seen from this, in the present invention, the dummy block remains adhered to the ferrite core and does not need to be removed, resulting in extremely good workability and processability.

As described above, the magnetic head according to the present invention does not need to be grounded by contacting the leaf spring or by soldering, thereby reducing the number of steps.
In addition, grounding failures due to poor contact do not occur during processing steps. Furthermore, the front part of the ferrite core is glued with the dummy block attached, rather than removing the dummy block and then bonding its shoulder directly to the opening of the metal case with conductive resin, improving work efficiency. do. In the method of taking a dummy block and gluing the case, it is necessary to use a special jig to prevent the spacer adhesive, that is, the molten glass, from adhering to the shoulder of the ferrite core, and if it does, it is difficult to remove it. There is a risk of damaging the shoulder of the core. With the present invention, there is no such concern at all, and back molding can be automated in production. Note that the present invention is not limited to the above-described embodiments, and it goes without saying that the case shape and the structure of the ferrite core can be changed as appropriate.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing a ferrite core assembly of a conventional magnetic head, FIG. 2 is a perspective view showing a metal case of the magnetic head, and FIG. 3 is a perspective view of a magnetic head according to an embodiment of the present invention. 4a, b, 5 and 6 are diagrams showing the state in the process of manufacturing the ferrite core according to the present invention, and FIG.
The figure is a partial side sectional view of the magnetic head according to the present invention. 1... Ferrite core, 1a, 2a... Ferrite core front part, 3... Metal case, 4, 5, 6...
...Spacer, 7...Opening, 9, 10...Dummy block, 11...Ferrite core material, 11a
...Shoulder, 13...Dummy block material.

Claims (1)

[Scope of utility model registration request] A spacer is fixed to both sides of the front part of the ferrite core, and a flat sloped surface is formed on both shoulders of the front part of the ferrite core so that the front part of the core as a whole becomes tapered, and a non-contact surface is formed in the entire area of this sloped surface. A head front part is formed by bonding a dummy block made of a magnetic metal material with a conductive adhesive, and a conductive adhesive is used to bond the entire circumference between the head front part and the front part of the metal case. magnetic head.