JPS6249644B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a combination magnetic head in a tape recorder.

Combination magnetic heads have the advantage of shortening the running distance of the magnetic tape and making the tape run more stable, and also have the advantage of eliminating the need to adjust the installation of each head. In a combination magnetic head, there is a phenomenon (hereinafter referred to as field-through phenomenon) in which the signal from the recording head jumps into the reproducing head during simultaneous recording and reproducing such as simultaneous monitoring and disturbs the reproduced signal.

Conventionally, in order to prevent this phenomenon, as shown in FIG. 1, shield cases 3, 3,
It had a structure in which the adjacent part of No. 4 protruded toward the tip. However, with this structure, the relationship between cores 1 and 2 and the magnetic tape deteriorates, resulting in 1K
Waviness occurred in the frequency characteristics below Hz, and the contour characteristics deteriorated.

This contour characteristic is based on the shape effect of the magnetic head, and can be improved by using a normal head as shown in FIG. 2 (a head having an arcuate front surface with the front gap near the top). However, in this case, the field-through phenomenon becomes significant. That is, it was conventionally thought that contour characteristics and prevention of field-through phenomenon were in a contradictory relationship.

The present invention has been made in view of the above-mentioned points.The present invention has been made in view of the above-mentioned points. A curved shield plate is interposed on the side of the recording head in order to prevent the field-through phenomenon without sacrificing contour characteristics.

Embodiments of the present invention will be described below with reference to the drawings. In FIG. 3, A and B indicate a normal recording head and a playback head, and 5 is a shield plate made of a soft magnetic material such as permalloy. ) is bent in an L-shape toward recording head A side along the running surface of
It forms a parallel plane that is almost parallel to the running plane,
The recording head A is in a non-contact state.

Here, if the tip of the shield plate 5 is bent toward the playback head B side, the signal emitted from the recording head A will be drawn into the playback head B side. Since this interference is eliminated, and furthermore, the signal attempting to jump from the recording head A to the reproduction head B can be effectively wrapped up, the effect of preventing the field-through phenomenon is extremely large.

Next, the shield plate 5 is made of permalloy, and the distance l between the L-shaped bent tip 5a, that is, the line connecting the upper surface of the above-mentioned parallel plane and the tops (front gap surfaces) of the recording head A and the playback head B, respectively. Fig. 4 shows the amount of field through when changing. According to this characteristic diagram, l=0 to 0.5 mm is good. That is, the bent tip 5a of the shield plate 5
Good characteristics are obtained when the upper surface of the head is formed to be equal to the line connecting the tops of the recording head A and the playback head B, or to be slightly inside the top of the head from the line. Note that a indicates the characteristics without the shield plate 5.

Note that since a magnetic tape runs on the front of the head, in actual use, the L of the shield plate 5 must be
As a countermeasure against wear and bending of the bent end portion 5a, a non-magnetic dummy plate 6 is used as shown in FIG. 5, or a non-magnetic resin is filled.

As described above, according to the present invention, the amount of field through is reduced, and there is no need to change the shape of the head that affects tape running, so there is no risk of adversely affecting the contour characteristics. Furthermore, assembly is simple because only a shield plate is added.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a conventional combination magnetic head, FIG. 2 is an outline diagram of a conventional combination magnetic head, FIG. 3 is an outline diagram of a combination magnetic head according to an embodiment of the present invention, and FIG. The characteristic diagram, FIG. 5, is an external view of a combination magnetic head provided with a dummy plate. 5...Shield plate.

Claims (1)

[Claims] 1. A shield plate is provided between the recording head and the playback head, each having an arcuate front surface with the front gap near the top, and the upper surface of the tip of the shield plate bent toward the recording head on the front side of each head. , a combination magnetic head characterized in that the head is formed to be equal to or slightly inside the top of the head from the line connecting the front tops of each head.