JPH01241008A - Magnetic head - Google Patents

Abstract

PURPOSE:To prolong the service life of a magnetic head and, at the same time, to stabilize the movement of magnetic tapes by constituting the dummy sliding section of the head of a material having a wear resisting property stronger than that of the material constituting the head core. CONSTITUTION:A tape sliding surface 2 is constituted of head cores 3 and 4 and a dummy sliding section 5A provided between the head cores 3 and 4 and a nonmagnetic or magnetic material having a wear resisting property which is stronger than that of the material constituting the head cores 3 and 4 against magnetic tapes is used for forming the dummy sliding section 5A. Therefore, even in a worn out state of this magnetic head, wear of the dummy sliding section 5A is a little and, microscopically, selective wear sigma1 of the section 5A is hardly recognized. The very little selective wear of the dummy sliding section 5A means that occurrence of vibrations caused by the selective wear of the section 5A when a magnetic tape is moved can be prevented. Therefore, the average service life of this magnetic head can be extended several times and the wow flatter can be suppressed to 0 dB practically.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a magnetic head for a VTR or an audio tape recorder, and particularly relates to a magnetic head in which the tape sliding surface J is composed of a head core and a dummy sliding part. .

(Prior art) Fig. 3 shows an example of an audio/control signal recording/reproducing head for a VTR, in which a tape sliding surface 2 located on the front of a case 1 has a tape sliding surface 2 for audio recording/reproducing and a rad core 3 for controlling signal recording/reproducing. It is composed of a head core 4 and a dummy sliding part 5 arranged between both head cores.

Figure f:tS4 shows an example of a recording/playback head of an audio tape recorder, and the tape sliding surface 7 located on the front of the case 6 is composed of a two-channel helad core 8 and a dummy sliding part 9. ing.

By the way, in conventional magnetic heads as shown in FIGS. 3 and 4, the head core and the dummy sliding portion are made of materials with similar wear resistance in order to prevent uneven wear. for example,
When the head core is made of a magnetic material such as permalloy, sendust, or ferrite, the dummy sliding part is made of a nonmagnetic material with wear resistance comparable to that of the herad core.

In the magnetic head shown in Fig. 3, the wear of the tape sliding surface is shown in Fig. 5 when the head core 3゜4 is made of general permalloy and the dummy sliding part 5 is made of a material with the same wear resistance. Shown in cross-section in the figure. As is clear from FIG. 5, the entire tape sliding surface 2 is heavily worn, and when viewed microscopically, uneven wear has also occurred. That is, the head core 3.4 is worn by a dimension X1 more than the front surface of the case other than the tape sliding surface and uneven wear σ1 occurs, and the dummy sliding part 5 is worn by a dimension ×2 and uneven wear σ2 occurs. Then, the relationship σ1≠σ2 substantially holds true.

(Problem to be Solved by the Invention) In the case of conventional magnetic heads, the head core is made of permalloy, which is inexpensive but has poor wear resistance, and the dummy sliding part is made of a material with the same wear resistance as the head core. In this case, the entire tape sliding surface wears out all at once as the magnetic head is used, resulting in a short service life. Moreover, even though it appears that the tape sliding surface 2 is reduced on average as shown in the t55 diagram, microscopically the uneven wear σ1 is quite large. σ2 occurs, and uneven wear σ1 of the head core part causes a drop in output and deterioration of high-frequency characteristics, and uneven wear σ2 of the dummy sliding part causes vibrations when running the magnetic tape, causing problems such as wow and 7 racks. .

SUMMARY OF THE INVENTION In view of the above points, an object of the present invention is to provide a magnetic head that can improve performance and stabilize magnetic tape running.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides a magnetic head in which the tape sliding surface is composed of a head core and a dummy sliding part, in which the dummy sliding part is larger than the head core. It is characterized by being constructed from a material with excellent wear resistance.

(Function) In the magnetic head of the present invention, the dummy sliding part has better wear resistance, and the head core wears out first, but the magnetic tape is supported by the wear-resistant dummy sliding part, so it can last for a long time. It becomes the lifespan. Further, no large uneven wear occurred on the dummy sliding part, the magnetic tape running became stable, and the conventional problem of wow and 7-lack was eliminated. That is, conventionally 1.
2 dB wow and fluff became essentially O dB.

(Example) Examples of the magnetic head according to the present invention will be described below with reference to the drawings.

PtIJ1 and 2 are vertical cross-sectional views of the front part of the VTR audio/control signal recording/reproducing head shown in FIG.
The figure shows the product before use (before wear), and Figure 2 shows the worn state after use. In these figures, the tape sliding surface 2 located at the front of the case is composed of a RAD core 3 for recording and reproducing audio, a RAD core 4 for recording and reproducing control signals, and a dummy sliding section 5A disposed between both head cores. ing. Here, the head core 3.4 is made of a magnetic material such as permalloy, sendust, or ferrite, and the dummy sliding portion 5A is made of a non-magnetic material or magnetic material that has better wear resistance against magnetic tape than the head core 3.4. (In this case, it is arranged with a slight gap to the helad gap). For example, head cores 3 and 4 are permalloy (Fc: 20%, N
i: 80%), the dummy sliding part 5A is made of a Fe-Ni composite (N
i is 4()% or less). Also, head core 3
, 4 may be made of permalloy (Fe: 20%, Ni: 80%), and the dummy sliding portion 5A may be made of an FeCo alloy (coated with 40% or less of Co), which has better wear resistance against magnetic tape. .

Note that the front portion outside the tape sliding surface 2 is also made of the same material as the dummy sliding portion 5A.

In the case of the above embodiment, as is clear from the cross-sectional view of the worn state in FIG. None. This means that it is possible to prevent vibrations during running of the magnetic tape due to uneven wear of the dummy sliding portion 5A, and furthermore, it is possible to prevent the occurrence of wow 7 rack.

Table 1 below shows the effects of the present invention, and shows the relationship between usage time and amount of wear of the herad core.

Table 1 (However, in the conventional product, the head core is made of permalloy and the dummy sliding part is made of the same wear-resistant material. In the example product, the head core is made of permalloy, and the dummy sliding part is made of permalloy (F e7
oN 1io) + 5Crs (numbers indicate weight %) From Table 1 above, the conventional product had a complete lifespan of about iooo hours, but the example product of the present invention had a lifespan of 1000 hours.
It can be seen that it can be used satisfactorily even after a period of time has passed.

(Effects of the Invention) As described above, according to the magnetic head of the present invention, since the dummy sliding portion is made of a material with better IT abrasion resistance than the head core, the following effects can be obtained.

(1) The magnetic tape wears out first, but since the magnetic tape is supported by the gummy sliding part, which has excellent wear resistance, even low-cost magnetic heads that use permalloy as the head core wear out on average. Lifespan has increased several times.

(2) There is no uneven wear on the dummy sliding part, vibration during running of the magnetic tape is eliminated, electromagnetic conversion characteristics can be maintained well, and wow 7 rack can be suppressed to substantially OdB.

[Brief explanation of the drawing]

FIG. 1 is a vertical cross-sectional view of a magnetic head according to an embodiment of the present invention before use, FIG. 2 is a vertical cross-sectional view after use, and FIG.
The figure is a front view showing an example of an audio/control signal recording/playback head for a VTR, #IJ4 is a front view showing an example of a recording/playback head for a Va tape recorder, and Figure 5 is a front view of the head shown in Figure 3. It is a sectional view taken along line ■-■. 1...Case, 2...Tape sliding surface, 3, 4...
Head core, 5,5A...dummy sliding part.

Claims (1)

[Claims] (1) A magnetic head in which the tape sliding surface is composed of a head core and a dummy sliding part, characterized in that the dummy sliding part is made of a material with better wear resistance than the head core.