JPH0418365B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a magnetic head having an extremely small track width, and is suitable for application to a VTR using a high coercive force medium (eg, metal tape).

Prior Art of the Invention In order to fully bring out the high coercive force characteristics of a metal tape, a magnetic head using an alloy magnetic material with a high saturation magnetic flux density has been proposed. FIG. 1 shows a conventional magnetic head of this type, in which a main body core A made of sendust or amorphous alloy is disposed in the middle, and a set of reinforcing cores B are attached from both sides of the main body core A. The reinforcing core B has a non-magnetic part D facing the front gear C and a magnetic part E facing the rear magnetic path.
It has the function of reinforcing the mechanical strength due to the thin overall thickness (equivalent to the track width) of the main body core A, and the function of increasing the magnetic path cross-sectional area of the rear magnetic path to improve the reproduction output characteristics. It's on. By the way, the total thickness of the main body core A cannot be made too small in order to ensure a certain manufacturing yield and not to impair mass productivity (currently the limit is about 20 to 30μ); It is extremely difficult to provide a magnetic head with a smaller track width (for example, 15 to 16 .mu.) as in recent camera-integrated VTRs (commonly known as 8 mm video).

Problem of the Invention: To provide a magnetic head with a small track width suitable for recording and reproducing high-frequency signals using an alloy magnetic material, and to ensure the initial reproduction output characteristics of this magnetic head over a long period of time. to do.

Summary of the Invention A magnetic head in which a reinforcing core having a non-magnetic part facing the front gap of the main body core, a through hole facing the winding hole, and a magnetic part is attached to a main body core made of an alloy magnetic material, The front gap of the main body core is provided with a notch for defining the track width, and the non-magnetic material of the non-magnetic material part is made to have greater abrasion resistance against the running tape than the alloy magnetic material of the main body core. To prolong the life of the magnetic head in terms of magnetic properties and mechanical properties by filling the notch with a second non-magnetic material having a higher abrasiveness than the non-magnetic material.

Embodiment of the Invention FIGS. 2 to 4 all show one embodiment of the present invention, in which FIG. 2 is a perspective view, FIG. 3 is a plan view, and FIG. 4 is an exploded perspective view. The magnetic head 1 of this embodiment includes a main body core 10 and a pair of reinforcing cores 30, 30.
and a coil (not shown).
The magnetic head is attached to the rotating disk of the VTR via a head base (not shown) to which it is attached. This magnetic head has its tape contact surface 2 in sliding contact with a high coercive force tape such as a metal tape, and travels relative to the tape in the direction of arrow 3 to record and reproduce high frequency signals.

The main body core 10 is a core half 1 made of Sendust.
1 and 12 are combined, and the front gap 1 is sandwiched between the winding hole 13 provided in the core half body 11 and extends upward.
4, and also has a back gap at the bottom.
A plurality of bonding materials (brazing material) are placed in spots between the abutting surfaces on the back gap side of each core half 11 and 12.
(not shown) is arranged, thereby attempting to integrate each core half.

The main body core 10 is provided with notches 16 for defining the track width 15 of the front gear 14 over the entire length of the core body 10 and on both sides with the front gap 14 in between in this embodiment. This notch is necessary only on the front gap 14 side, and may be omitted from the back gap 17 side as shown in FIG. 5 to prevent an increase in magnetic resistance as much as possible. This cutout 16 has a depth 18 of about 7μ and a width 19 of about 500μ, and is formed by etching. Furthermore, main body core 1
The total thickness 20 of 0 is 30μ, and the track width 15 is about 16μ. This notch 16 is filled with a non-magnetic material such as epoxy resin, and is molded to be flush with each adjacent surface of the main body core 10. 21 is a filled non-magnetic material.

Both reinforcing cores 30, 30 have the same configuration, and one will be explained below. The reinforcing core 30 is attached to the side surface of the main body core 10 adjacent to the tape contacting surface,
The outer shape of this abutting surface is the same as the outer shape of the main body core 10. Both are made using a suitable adhesive such as cyanoethyl acrylate resin (commonly known as instant adhesive).
are joined and integrated. In addition, this reinforcing core 30
The total thickness 31 is approximately 100μ.

This reinforcing core 30 has a non-magnetic part 32 facing the front gap 14, a through hole 33 facing the winding hole 13, and a magnetic part 34 facing the rear magnetic path.
It is equipped with The magnetic material part 34 is suitably made of ferrite material, which has a higher specific resistance than the main body core, and the non-magnetic material part 32 is suitably made of glass (with a relatively low softening point, e.g. (around 280℃) is suitable. Integration of both parts is achieved by fusing with this glass, but if necessary, a separate adhesive may be used. The glass constituting the non-magnetic material portion 32 is made to be less abrasive to the running tape than the second non-magnetic material filled in the notch 16, such as epoxy resin.

In this way, in the magnetic head of the present invention, the order of wear resistance against the running tape is determined by the main body core 10,
The reason why the non-magnetic material portion 32 of the reinforcing core and the non-magnetic material 21 within the notch are made larger in this order is to increase the reproduction output characteristics compared to the initial value while the magnetic head is in use. During this use, the main body core 10 is the least susceptible to wear, and the front gap 14 runs closely and relatively to the tape, so that so-called spacing loss is constantly kept small, and the depth of the front gap 14 is This is because the reproduction output is improved by gradually decreasing the so-called depth. On the other hand, if the abrasion of the non-magnetic materials 32 and 21 is made smaller than that of the main body core 10, the spacing loss will increase even though the depth remains, and the life in terms of magnetic properties will come to an early end.
Note that the wear rate of the main body core 10 is
And compared to the case where the non-magnetic material 21 is not provided,
Since the stress on the main body core is reduced due to the contact with these, the life in terms of mechanical properties can be extended.

In this embodiment, the main body core is sandwiched in the center and the reinforcing cores are arranged on both sides, but the reinforcing cores may be arranged only on one side of the main body core. Further, although the notch is shown as being provided in both core halves constituting the main body core, the notch may be provided in only one core half or only on one side thereof.

Effects of the Invention The present invention has a reinforcing core attached to the main body core made of an alloy magnetic material, and a notch for defining the track width in the front gear part of the main body core, making it suitable for high coercive force tapes. It is useful to be able to provide a magnetic head that satisfies both its mechanical and magnetic characteristics over its lifetime. Further, by filling the notch with a non-magnetic material that is more abrasive to the running tape than the main body core and reinforcing core, the above effect can be further enhanced.

[Brief explanation of drawings]

FIG. 1 is a perspective view of a conventional magnetic head. 2 to 4 show one embodiment of the present invention,
FIG. 2 is a perspective view, FIG. 3 is a plan view, and FIG. 4 is an exploded perspective view. FIG. 5 is a perspective view of another embodiment of the main body core. Explanation of main drawing numbers, 10... Main body core, 30... Reinforcement core, 16... Notch, 21... Non-magnetic material.

Claims (1)

[Scope of Claims] 1. On the side surface of a main body core made of a metal magnetic material having a front gap extending from the tape contact surface toward the winding hole, the track width of the front gap is defined to be less than the total thickness of the main body core. A notch is provided on the side surface of the main body core where the notch is provided, and a non-magnetic material portion facing the front gap, a through hole facing the winding hole, and a rear magnetic path of the main body core are provided. A magnetic head is formed by bonding a reinforcing core having a magnetic material portion facing the reinforcing core, wherein the non-magnetic material portion of the reinforcing core is made of a non-magnetic material that is more abrasive to the running tape than the metallic magnetic material constituting the core body. A second material is made of a magnetic material, and a second material is provided in the notch, the abrasion of which is greater than that of the non-magnetic material.
A magnetic head characterized by being filled with non-magnetic material. 2. The magnetic head according to claim 1, characterized in that one set of reinforcing cores is arranged so as to sandwich the main body core.