JPS5819698Y2 - magnetic head - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a magnetic head suitable for recording video signals and the like at high density on a medium such as a magnetic tape, and/or reproducing the signals from the medium. Although the head is widely used for processing video signals or similar signals, the description will be made considering its application to a video tape recorder (hereinafter referred to as a VTR).

In order to improve the recording density of VTRs, attempts have been made to narrow the track width of the magnetic head, and the track width has changed from the initial 200 Pm width to the unified standard 115
.mu.m width, and recently, 60 .mu.m width has appeared to enable long-term recording and playback with cassettes.

However, since the magnetic head of a VTR rotates at high speed, a narrow track width increases wear on the magnetic head and shortens its life.

Therefore, in consideration of this wear resistance, various magnetic heads having shapes as shown in FIG. 1 have been proposed.

The magnetic head is made by squeezing the magnetic core from both sides of the core.
The overall thickness is thick, only the track part is narrowed, and the constriction part is filled with glass, and the magnetic head opening and C are each constricted in an arc shape from one side wall or both side walls at the abutting part of the pair of magnetic cores. More than half of the total thickness of the two magnetic heads is filled with glass, and each has a structure in which the total thickness is larger than the actual track width to improve wear resistance.

However, since the effective track width of the second type of magnetic head is not centered, it exhibits a phenomenon of uneven contact, which has a negative effect on the performance and envelope of the magnetic head, so it is not widely used today. Because it is not filled with glass, magnetic powder clogs occur.

Therefore, at present, A-shaped magnetic heads are the mainstream.

but. With current processing technology, it is difficult to increase the depth of the groove that defines the track width (width in the track extending direction) without causing so-called chipping, so the depth of the groove must be made shallow. .

Based on this point, it is necessary to satisfy both the conflicting demands of high density and wear resistance (Learning from the shape of A above, the total thickness should be increased to 20 mm.
0 μm, and the effective track width was set to 60 μm.

Moreover, when a magnetic head whose rim was filled with glass was used to record and reproduce a color video signal used in a standard type VTR, color flicker was observed.

It has been found that this color flicker decreases as the total thickness is decreased, as shown in FIG. 2, and exhibits a good value when the total thickness is 120 μm or less.

Considering compatibility, this total thickness needs to be around 100 pm.

However, if the total thickness of such a shape becomes around 100 μm, it becomes impossible to put it to practical use due to wear resistance.

Therefore, by developing the magnetic head with the shape shown in Fig. 1 and 2, as shown in Fig. 3, a magnetic head with a configuration in which both sides of a magnetic core having a desired head gap are reinforced with glass.
RAD is also considered, but this method is difficult to obtain accurate track width when the track width becomes as small as 60 μm.
Further, there are other drawbacks such as difficulty in aligning each core with each other to form a necessary gap length.

In view of the above points, the present invention provides a magnetic head with a novel shape that is wear-resistant, adaptable to high density, and excellent in manufacturability.

In other words, the present invention increases the total core thickness to satisfy wear resistance, and also defines the track width to prevent color flicker and chipping in the working gap. An object of the present invention is to provide a magnetic head comprising a shallow second groove defining a width and a deep first groove following the second groove, with both grooves being filled with a non-magnetic material. It is.

FIG. 4 shows an embodiment of the magnetic head according to the present invention, showing its front view.

The magnetic cores 1 and 2 are abutted against each other with a working gap 3 interposed between them, and the tape contacting surfaces of the magnetic cores 1.2 define the total thickness W□ and the depth of the working gap 3. First side walls 1a, 1b, 2a, 2b extending in the depth direction and a thickness W2 adjacent to the first side walls extending in the depth direction are narrower than the total thickness W1 and wider than the track width T. The second side wall 1 c , 1 d > 2 c , 2 d
and at least one of the 20
The contact surface further extends from the second side walls 2c, 2d to the working gap 3.
A third side wall 2 defining a track width T formed toward
et2f.

Therefore, this magnetic head has a track width T of the first . He is trying to define it by a groove formed by the second grooves 4 and 5.

Note that the first concave groove 4 is the first concave groove 4. The second side wall 2c is defined by an extended side surface 2a', 2c' of each second side wall 2a, 2c, a side surface 3' substantially orthogonal to the extended side surface including one working gap 3, and a second side wall 2c, while a second groove 5 is the extended side surface 2c',
It is defined by a side surface 3' and a third side wall 2e.

Thickness W2 should be selected as W2-2 x Homare x G + T, based on the empirical rule that color flicker will not occur even if this thickness is within the width of the guard band G, so the guard band G is 40 μm. , when the track width T is 60 μm.

W2 may be set to 113 μm.

If the second concave groove 5 has to be deeply grooved from the working gap, variations in the track width T and chipping will easily occur, making it difficult to achieve accuracy.

The depth may be sufficiently smaller than the depth of the first groove as measured from the side surface including the working gap.

As mentioned above, the magnetic head of the present invention has a wide total thickness to improve wear resistance, and the width W2 of the magnetic core in the part involved in color flicker is related to the girt band and track width. The width of the magnetic core is narrower than the total thickness, and the working gap is defined by a small groove (second groove) near the working gap of the magnetic core. The track width can be reduced while maintaining abrasion resistance, and even if the density is increased in this way, the occurrence of color flicker can be suppressed to a practically negligible level, which is practical.

[Brief explanation of drawings]

Figure 1 shows a conventional magnetic head, Figure 2 is a characteristic diagram showing the overall thickness versus color flicker (crosstalk level), and Figure 3 is a front view of another magnetic head. show. FIG. 4 is a front view of a magnetic head according to the present invention. Explanation of main drawing numbers, 1, 2...Magnetic core 4...
...First groove, 5...Second groove.

Claims (1)

[Scope of utility model registration request] In a magnetic head in which a magnetic core is formed by abutting each other with an operating gap interposed in the middle, a groove for defining a track width is provided in the magnetic core, and the groove is filled with a non-magnetic material. a first side wall defining a total thickness of the magnetic core and extending in the depth direction of the working gap; and a first side wall adjacent to the first side wall that is narrower than the total thickness, and each extended side surface of a second side wall formed across the left and right magnetic cores with the working gap wider than the track width as a boundary; substantially orthogonal to each extended side wall, including the working gap and extending in the depth direction thereof; extending sides,
and a first groove surrounded by the second side wall; a third side wall adjacent to the second side wall and defining the track width;
a second groove surrounded by an extended side surface of the side wall and a side surface forming the working gap, the first groove having a depth compared to the depth of the second groove. and a core thickness defined by the second sidewall is selected to have a size that substantially does not extract crosstalk from adjacent tracks.