JPH0340202A - Magnetic head and manufacture - Google Patents

Abstract

PURPOSE:To enable stable recording and reproducing by making the notched part of a head longer on a back side rather than on a front side in a sliding direction. CONSTITUTION:This magnetic head is constituted so that 0-order interference stripes can be always positioned on a head gap 1 even when relative speed between the head and a tape is high. Namely, by making a back side L2 long in the traveling direction of a head notch 2, the magnetic tape can get contact with the head gap 1 in an optimum condition. Accordingly, even when the relative speed between the magnetic head and magnetic tape is enlarged, the position of the head gap 1 is always made optimum and a contact state between the tape and head can be kept stable. Thus, satisfactory recording and reproducing can be executed.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a magnetic head used in high-speed rotation video tape recorders and the like, and a method for manufacturing the same.

In a conventional video tape recorder, a magnetic head is fixed so as to protrude by a predetermined amount from a cylinder around which magnetic tape is wound at a predetermined angle.

A conventional magnetic head will be explained using FIGS. 2 and 3. FIGS. 2(a) to Ig5 schematically show a method for manufacturing the head. An enlarged view of the notch 22 formed by machining the magnetic material block to form a track groove as shown in FIG. 6(b) is shown in FIG. 8(8).

Track groove depths X and Y (head notch portion) in the sliding direction with respect to the head gap (joint surface) were configured to have the same depth on the front side and the rear side. Further, as shown in Fig. 3, the shape of the magnetic head for VH3 is usually 9.0 to 11.0 m in the sliding direction, and r in the core thickness direction.
is approximately 211Il.

In this magnetic head, the lengths LL and L2 of the head notch 2 are made equal with respect to the head gap l. By this method, when recording and reproducing are performed while the position of the magnetic head relative to the rotating cylinder is fixed, the relative speed between the magnetic head and the magnetic tape increases in proportion to the speed, as shown in FIG. 4, a theoretical curve 41. From the curve 42 obtained from the experimental results, it was found that the output was significantly reduced.

This phenomenon occurs when the relative velocity is 5.8 m as shown in Figure 5.
/see, the center of the zero-order interference fringe is shown as 51 elliptical fringes on the magnetic head gap l. but,
Relative speed is twice as high as 11.6m/sec, and IT is tripled
, 4 m/sec, the center of the 0th order interference fringe becomes 52.53 with respect to the Herad gap l.
It was found that the output decreased due to a tendency to shift backward in the sliding direction.

Problems to be Solved by the Invention As mentioned above, when recording and reproducing are performed while the position of the magnetic head relative to the rotating cylinder is fixed, as the relative speed of the head/tape increases, the contact position between the magnetic head and the magnetic tape shifts. There was a problem in that the position of the helad gap of the magnetic head deviated from the optimal contact position.

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention provides a magnetic head in which zero-order interference fringes are always located on the head gap even when the relative speed of the head and tape is large. It was configured as follows. By lengthening the rear portion of the head notch in the running direction, the magnetic tape is configured to optimally come into contact with the head gap.

Effects of the present invention The above-described configuration allows the position of the magnetic helad gap to always be at an optimal position even when the relative speed between the magnetic head and the magnetic tape increases, and the contact state of the tape head can be maintained in a stable state. Therefore, good recording and playback becomes possible.

EXAMPLE Hereinafter, a magnetic head according to an example of the present invention will be described with reference to the drawings. Figures 1 and 2 are, respectively,
1 shows the overall configuration of the present invention. Figure 1(a) shows
The structure of the magnetic head is shown. FIG. 1(b) is a top view of the head. The ratio of the notch length Ll on the front side and the notch length L2 on the rear side in the sliding direction of the head notch in FIG.
=2 to 4.

Here, the head notch 2 is an area filled with glass formed by melting lead-based glass into the trunk groove machined during head manufacturing, and various shapes can be created by changing the track groove depth. Can be manufactured.

When a current is passed through the coil 4 in FIG. 1, a magnetic field is generated in the core 6, and a magnetic tape is recorded by the leakage magnetic field generated by the gear knob 1. Moreover, FIG. 2(a) shows a ferrite block in which winding grooves are formed. A is a front block in the tape sliding direction, and B is a rear block. FIG. 2(b) shows the shape of the track groove 22 of the first block 21 with the grooves squared. FIG. 6 shows the experimental results of the relationship between the length ratio L2/Ll of the head notch and the output. From this result, it was found that the output increases more when Ll<L2 and the ratio of L2/Ll is 2 to 4 than when L1=L2. Therefore, FIG. 2 (chain, ω) shows an enlarged view of the notch portion of the ferrite block from the Z direction. The track groove depth X on the front side in the sliding direction and the trunk groove depth Y on the rear side are not X=Y as in the conventional case shown in Fig. 2(g), but as shown in Fig. 2(b).
As shown in the figure, the track groove depth is machined so that the Y track groove depth is longer than that of the X track groove. For example, the depth of the track groove is set so that Y/X=2 to 4. Also, ferrite block A
, B, respectively, where the bonding surfaces 23 become the magnetic head gaps 24. By processing in this way, the length ratio L2/Ll of the head notch can be changed. If processed in this way, the length ratio of the head notch Ll
/L2 can be changed. By setting the length ratio L2/L1 to 2 to 4, an optimal magnetic head as shown in FIG. 1 can be obtained.

Effects of the Invention As described above, in the present invention, the contact position between the magnetic head and the 41 tape is shifted due to a change in the relative speed between the rotating magnetic head and the magnetic tape. Therefore, by lengthening the rear portion of the head notch in the running direction, the position of the hend gap is set to an optimum position, which has the effect of making extremely stable recording and reproduction possible.

[Brief explanation of drawings]

FIGS. 1(a) and 1(b) are block diagrams of a video rad according to an embodiment of the present invention, and a block diagram of a sliding surface. FIG. Figure 3(a). (b) is a configuration diagram of the hend of a conventional video head and a configuration diagram of the sliding surface. Figure 4 is a characteristic diagram of output according to relative velocity. Figure 5 is a head gap of zero-order interference fringes with various relative velocities. FIG. 6 is a characteristic diagram of the output with respect to the ratio of the notch length on the front side and the notch length on the rear side in the sliding direction. l...Head gap, 2...Head notch (glass), 3...Joint surface, 4...
...Coil, 5...Head width, 6...
Core, Ll...Length of the core on the front side in the sliding direction,
L2... Length of the core on the rear side in the sliding direction, 21.
... Core material, 22 ... Track groove depth, 23 ... Joint surface, 24 ... Window, 41
...Theoretical relative speed and output characteristics, 42...
...Actual relative speed and output characteristics, 51...
...0th order interference fringe of 5.8m/sec, 52...
0th order interference fringe of 11.6 m/sec, 53...
・0th order interference fringes at 17.4m/sec.

Claims (3)

[Claims] (1) A magnetic head characterized in that the notch portion of the head is longer on the rear side than on the front side in the sliding direction with respect to the magnetic head gap. (2) A magnetic head characterized in that the notch portion of the head has a length ratio of 2 to 4 on the front side and the rear side in the sliding direction with respect to the magnetic head gap. (3) A method for manufacturing a magnetic head, characterized in that, in machining a track groove in a material block of a magnetic head, the depth of the groove is deep in the core on the rear side in the sliding direction, and shallow in the core on the front side in the sliding direction.