JPS647453Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a magnetic head, and particularly to a magnetic head in which a core is housed in a ceramic case and fixed with resin.

In magnetic heads for recording and playback of VTRs, the front core is usually installed inside the head case, the core is hardened and fixed with resin, and the front of the head (magnetic tape sliding surface) is polished along with the case to produce the product. The inside of the case is sealed with resin, etc., except for the front surface of the front core, to prevent it from being affected by the humidity of the outside air. In this case, if the case is made of ceramic, the case volume can be prevented from swelling due to temperature and humidity, and the reliability of the product can be improved. FIG. 1 is a side view showing a magnetic head using a ceramic case in a state in the process of being manufactured. This example is an example of manufacturing an erasing head using a three-legged front core to form two gaps. A recess 10 is formed in one side 4 of the ceramic case 2. In order to make the front surface of the head a good sliding surface, the front surface 3 of the ceramic case 2 is closed and the front core is inserted into this recess space. 1 and case 2
The front core 1 is polished together with the front core 1 to the position indicated by the broken line 5. To determine the length a of the front core 1 from the front surface of the head after polishing,
Conventionally, front core 1
The front end 1a of the holder is brought into contact with the closed inner wall 2a of the front part of the case, and the holder is polished to a predetermined position shown by a broken line 5 with this surface 6 as a reference. This position will be the front of the head. A portion A between the rear end 1b of the front core 1 and the rear inner wall of the case and a portion B between the core side portion and the case are fixed by molding with epoxy resin or the like after the core is assembled. In this case, from the viewpoint of assembly workability, the distance between part A at the rear end of the core is set large, so when a product reliability test is performed, especially a high temperature and high humidity test, the resin in part A absorbs moisture and swells, causing the volume to decrease. As a result, a force is generated that pushes the front core in the direction of arrow C, and the front end of the front core tends to protrude from the carefully polished front surface of the head. Depending on the type of mold resin used, the resin at the rear of the core may swell due to the effects of temperature, humidity, etc. due to long-term use of the magnetic head. There is a risk that the degree of damage will gradually worsen and cause scratches on the magnetic tape.

The object of the present invention is to eliminate such problems and provide a magnetic head with improved reliability.

For this purpose, in the magnetic head of the present invention, the inner wall of the ceramic case is formed in such a shape that the inner wall of the case is in direct contact with the rear end of the front core. A polishing surface is formed at a predetermined position from the contact surface at the end, and this polishing surface is used as the surface in contact with the magnetic medium at the front of the head.

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

FIG. 3 is a perspective view of the ceramic case of the magnetic head according to the present invention before polishing, and FIG. 2 is a side view of the case with a ferrite core installed therein. Side part 4 of ceramic case 2
As explained in FIG. 1, a recess 10 as shown in the figure is formed, and the front core 1 is installed in this portion. Ceramic case 2 of this invention
A projecting wall 7 is formed on the inner wall of the recess on the side opposite to the front surface of the head, and the core is installed so that the rear end 1b of the front core 1 comes into contact with the tip end surface of the projecting wall 7, as shown in FIG. In this state, the front end 1 of the front core 1
a is the closed part at the front of the case, that is, the inner wall 2 of the front recess;
There is a certain amount of gap A' with respect to a. The front core 1 is inserted into the recess 10 on the side of the case so as to be in this state, and the space between part B of the side of the core and part A' of the core tip 1a is fixed with epoxy resin. In this case, since the rear end portion 1b of the front core and the front end surface of the rear projecting wall 7 of the case recess 10 are in close contact, no resin is present between them. Using this projecting wall surface as a reference surface 6', the case front surface 3 and the front core front end 1a are polished to a position 5' (broken line position) where the front core 1 has a predetermined length a. Front Core 1 does not protrude forward due to resin swelling during high-temperature, high-humidity tests or in actual use, and the polished surface on the front of the head is maintained well, which, combined with the non-swelling property of the ceramic case, ensures reliability. A magnetic head with high magnetic field strength can be obtained.

[Brief explanation of the drawing]

Fig. 1 is a side view showing a state in which a magnetic head using a conventional ceramic case is being manufactured, Fig. 2 is a side view showing a state in which a magnetic head according to the present invention is in the process of being manufactured, and Fig. 3 is an embodiment of the magnetic head shown in Fig. 2. FIG. 3 is a perspective view of a ceramic case in FIG. 1... Front core, 1a... Front end of front core, 1b... Rear end of front core, 2... Ceramic case, 6, 6'... Reference surface, 7... Projection wall, 1
0... Concavity.

Claims (1)

[Scope of utility model registration request] In a magnetic head in which a core is housed in a ceramic case, the ceramic case has an inner wall surface that contacts the rear end of the front core, and the ceramic case has an inner wall surface that is in contact with the rear end of the front core at a position a predetermined distance from the contact position between the inner wall surface and the rear end of the front core. 1. A magnetic head, wherein a polished surface is formed on the magnetic head, and the polished surface serves as a surface in contact with a magnetic medium at the front end of the front core.