JP2568497B2 - Magnetic head - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-track magnetic recording / reproducing head.

2. Description of the Related Art In an audio magnetic recording technology, a method of performing magnetic recording 2 and reproduction in stereo has been conventionally used in order to give a sense of realism and power. Also, not only two tracks,
Recording and reproduction may be performed by a multi-element magnetic head of a track or more.

In such a magnetic recording technology, if there is a magnetic flux leaking from an adjacent track, when reproducing an analog signal, it interferes with each other when reproducing, the separation between the two tracks becomes unclear, and a reading error occurs in a digital signal. Will be connected.

In order to remove the leakage magnetic flux from these adjacent tracks, a magnetic head generally using a metal magnetic material generally has a core 2 and a core 2 surrounded by a case 1 as shown in FIG.
A magnetic shield plate 3 wider than 2 'is inserted between the tracks, and a filler 4 made of synthetic resin
To reduce and eliminate the leakage flux. Conventionally, as shown in FIG. 7, a nonmagnetic plate is used as a shield material for the ferrite magnetic head cores 6, 6 '.
7, 7 ', the magnetic plate 8 is replaced with the non-magnetic plate 7, the magnetic plate 8,
The non-magnetic plate 7 'is laminated in a sandwich manner in the order of the core 6,
It was inserted between 6 'and integrated. Further, in order to increase the shielding efficiency and absorb the leakage magnetic flux, the magnetic plate 8 is made of a metal magnetic material such as permalloy. In this case, as a material for the shielding material, a metal material such as a copper plate or a nickel silver plate or a ceramic is used as the nonmagnetic material.

Problems to be Solved by the Invention However, in order to integrate the shield material and the core, ferrite, which is an oxide ceramic, and a metal material are materials having completely different properties both physically and mechanically. From there, there was only a method of bonding with resin. As a result, the resin protrudes from the core due to a change in environmental conditions or heat generated during tape running, and the magnetic powder of the tape is mixed into the resin, resulting in damage to the tape.

Means for Solving the Problems For this reason, the present invention provides a plurality of core members, a shield member provided between the plurality of core members, and a holding member sandwiching the shield member and the plurality of core members. The non-magnetic plate and the magnetic plate which are constituent members of the shield member are both housed in the concave portion provided in the holding member, and are used for bonding between the bonding glass of the plurality of core bodies and each member. The difference in the coefficient of thermal expansion of the bonding glass was set within 5%.

Action With this configuration, it is possible to improve the wear resistance and to be resistant to thermal changes. Further, it is possible to prevent unnecessary stress from being applied to the shield member.

Examples Hereinafter, the present invention will be specifically described.

FIG. 1 shows an embodiment of a magnetic head according to the present invention, which is a stereo magnetic head using a metal magnetic material such as permalloy generally used for a tape recorder. Reference numerals 10 and 10 ′ denote ferrite cores formed by molding a ferrite material, and magnetic gaps 12, 12 ″ and 12 are formed in glass 11 to predetermined dimensions. Reference numerals 13 and 13 ′ denote holding members made of ceramics. The ferrite cores 10, 10 'bonded to each other by the glass 11 are provided with shield grooves 14, 15, 16 so as to face each other. Also each groove 1
4 ', 14 ", 15', 15", 16 ', 16 "are provided, and the respective grooves have a positional relationship corresponding to 14, 15, and 16.
The width m of the processed groove at that time is determined by the track dimensions l, n and the track pitch l + m or m + n. 17,1
Reference numeral 7 'denotes a non-magnetic plate made of ceramics, and reference numeral 18 denotes a ferrite plate in a processed state or a heat-treated state, which is made of the same material as the ferrite cores 10, 10'.

The total thickness of the non-magnetic plate 17, the ferrite plate 18, and the non-magnetic plate 17 'is formed to be about 0.02 to 0.2 mm thinner than the width m of the processing groove. FIG. 2 is a top view of a magnetic head according to an embodiment of the present invention, and FIG.
The figure is the front view. In FIG. 3, the cut surface, that is, the surface A in FIG. 4 is processed into a mirror surface, and the ferrite 21 bonded to the ceramic plate 20 by glass is machined, and then the surface B is mirror-finished. The coil 22 is inserted there.
FIG. 5 shows a state in which a closed magnetic circuit including the back shield plate 19 is formed.

Non-magnetic plate for shielding that contacts the running surface of magnetic tape 1
The ferrite plates 7, 17 'and the ferrite plate 18 are made wider by at least 1 mm or more than the ferrite cores 10, 10' forming the tracks. Also, the holding members 13, 13 '
Are the shield plate inserts 14, 15, 1 of the ferrite cores 10, 10 '.
Grooves 14 ', 15', 16 'and grooves 14 ", 15", 1
6 "is processed by a diamond saw.
The depth P of the groove at this time is determined by the following equation.

P = (N−M) / 2 + α N ≧ M + 1 Also, α is suitably in the order of +0.05 to 0.2, and may be a value larger than that. Cause it to occur.

Next, each part is fixed with a jig, a bonding glass is placed thereon, and when the core 1 is a Mn-Zn ferrite, heat treatment is performed in an electric furnace in a reduced atmosphere with a required temperature gradient. By doing so, the bonding glass is melted and fixed.

Here, it should be noted that, at this time, the difference in the coefficient of thermal expansion between the constituent material of the bonding glass and the constituent material of the glass 11 is within 5%, and the difference in the working temperature in the electric furnace is 50%. The temperature must be lower than or equal to ° C. That is, when there is not much difference between the two working temperatures, the magnetic gaps 12,1, which are the most important for the characteristics of the magnetic head,
This is because the widths of 2 ′, 12 ″ and 12 may be changed. The expansion coefficients of the two glasses have been described above, and the same is required for the cores 10 and 10 ′. Unless the difference in the expansion coefficient between the users is within ± 5%, cracks may occur in the state of being removed from the electric furnace, and it will not be usable.

FIG. 2 shows a state of bonding with glass, in which the non-magnetic plates 17, 17 'are larger than the width M of the cores 10, 10'.
And the width N of the shield block 7 made of the ferrite plate 18
Is increased, and is fixed by the glass.

FIG. 3 shows that, when viewed from the side, each part is fixed by glass, so that it can be fixed to a cutting jig and cut by a diamond saw. The cut surface, that is, the A surface is processed into a mirror surface with abrasive grains such as diamond, and a non-magnetic plate 20 made of ceramics is bonded to a core block 21 made of the same material as the cores 10 and 10 '. Then, a groove is formed in a direction indicated by an arrow C by a diamond saw in a direction indicated by an arrow C to form a closed magnetic circuit with the cores 10 and 10 '.
Next, a groove is formed in the direction of arrow D. At this time, the groove is cut to the position of the non-magnetic plate 20 to be separated into tracks. And B side is A
After the mirror finishing with abrasive grains such as diamond,
Insert the coil 22.

Next, after the back shield plate 19 is fixed with a resin or the like corresponding to the ferrite plate 18 in the shield block composed of the non-magnetic plates 17, 17 'and the ferrite plate 18, the coil portion is further adhered to a predetermined position, Fixed and closed magnetic circuit. At this time, the width R of the back shield plate 19 is also substantially the same as the width N of the shield block composed of the non-magnetic plates 17, 17 'and the ferrite plate 18, and needs to be wider than the width of the coil 22. . The material of the back shield plate 19 is a non-magnetic plate 17,1.
It may be made of the same material as the magnetic material 18 of the shield block 7 composed of the 7 'and the ferrite plate 18. However, in order to further improve the efficiency, annealing is performed under predetermined conditions to remove the work-affected layer of the ferrite material. It is more effective to use a material having improved magnetic permeability or use a metal magnetic material having a high magnetic permeability, for example.

The present invention provides a plurality of core members, a shield member provided between the plurality of core members, and a holding member that sandwiches the shield member and the plurality of core members, and is provided on the holding member. The recess contains both the non-magnetic plate and the magnetic plate that are the components of the shield member, and the difference in the coefficient of thermal expansion between the bonded glass of multiple cores and the bonding glass used for bonding between the members. Is set to 5% or less, magnetic shielding between head cores can be effectively performed, and since heat resistance is high, bonding with glass can be performed. Therefore, heat generated by friction with a recording medium such as a tape can be achieved. No inconvenience occurs.

Furthermore, since the magnetic plate is sandwiched between the non-magnetic plates in the recess formed in the holding member and housed in a state where the mechanical strength is improved, stress due to thermal expansion is applied between the holding member and the shield member. Also, since cracks and the like can be prevented from entering the magnetic plate, stable recording or reproduction can be performed without deteriorating the shielding effect.

Further, by setting the thermal expansion coefficient of the bonding glass and the bonding glass within 5%, the stress applied to the magnetic plate can be further reduced, so that cracks in the magnetic plate can be further suppressed.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view showing an embodiment of the magnetic head of the present invention, FIG. 2 is a top view of the same, FIG. 3 is a side view in the same manufacturing process, FIG. FIG. 5 is a side view of the same, and FIGS. 6 and 7 are top views of a conventional magnetic head. 10: Ferrite core, 12: Magnetic gap 17: Non-magnetic plate, 18: Magnetic plate

Claims (1)

(57) [Claims] 1. A plurality of cores in which a pair of cores are joined by a bonding glass via a magnetic gap, and disposed between the plurality of cores, and longer than the length of the plurality of cores, Moreover, a shield member formed by sandwiching a magnetic plate with a non-magnetic plate, a holding member having a recess for sandwiching the plurality of core members and the shield member and receiving an end of the shield member, and A core body, a bonding glass for bonding the shield member and the pressing member, and a recess provided in the pressing member accommodates both the non-magnetic plate and the magnetic plate, which are constituent members of the shield member. And a difference in thermal expansion coefficient between the bonding glass and the bonding glass is set to 5% or less.