JP2599830Y2 - Magnetic head - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic head, and more particularly to a magnetic head used as a rotary head for a video tape recorder, a DAT (digital audio tape recorder), or the like.

[0002]

2. Description of the Related Art A perspective view of FIG. 4 and a three-view drawing of FIG. 5 are views showing an example of a conventional magnetic head. For example, in the case of 8 mm video, a rotating drum (hereinafter, "drum") is used as a video head.
Attached). In both figures, cores 1a and 1b made of Mn-Zn single crystal ferrite are opposed via a non-magnetic glass member 2 to form a gap 3 for performing magnetic recording and reproduction on a magnetic tape (not shown). .

A tape sliding surface 4 gently curved in a substantially D direction is formed in the front-rear direction of the gap 3 with respect to the rotation direction of the drum indicated by an arrow D in FIG. With the rotation of, the surface of the tape sliding surface 4 slides from the core 1a side to the core 1b side.

A flat stepped surface 5 is formed on both sides of the tape sliding surface 4 in the direction of forming the gap 3 so as to have a step with respect to the tape sliding surface 4. The contact position of the magnetic tape with the sliding surface 4 is determined, and the running state of the tape is stabilized.

In FIG. 5 , a step processing surface 5 of the conventional magnetic head is a tape running surface (dashed line T in the drawing) when the magnetic tape runs while sliding on the tape sliding surface 4.
Is formed so as to be parallel to the surface indicated by
The step processing depth B1 from the most protruding portion of the tape sliding surface 4 is about 100 to 150 (μm).

On the tape sliding surface 4 side of the core 1b, a flat stepped surface 6 having a step with respect to the tape sliding surface 4 and the step processed surface 5 is formed. As a result, when the magnetic tape slides on the tape sliding surface 4, the magnetic powder separated from the surface of the magnetic tape is transferred to the tape running surface and the stepped surface 6.
The magnetic powder is released from the surface of the magnetic tape in the gap between the magnetic powder and the magnetic powder, and the adhesion of the magnetic powder to the gap 3 or the tape sliding surface 4 is prevented.

As described above, in the conventional magnetic head, the shape and the shape of the magnetic head are taken into consideration only in stabilizing the contact position and running state of the magnetic tape with the gap 3 and the tape sliding surface 4. The dimensions were fixed.

[0008]

FIG. 6 is a diagram showing a problem of the conventional magnetic head, and is an example of a result obtained by measuring an electric signal output from the magnetic head of FIG. 5 with a spectrum analyzer. The measurement range in the figure is 0 to 10
MHz, dynamic range is 50dB. I is an electric signal when the magnetic tape is slid, ie, a signal when the tape is slid, and II is an electric signal when the magnetic tape is not slid, ie, system noise including amplifier noise.

The measuring conditions are as follows: temperature 25 ° C., humidity 20%
And the step processing depth B1 = 130 (μm). In addition, the meaning of electrical signals, such as video signals, audio signals, and pilot signals, that are measured as discrete spectra at specific frequencies is omitted.

In FIG. 6 , a system noise II is a total sum of noise generated from a magnetic head itself or an amplifier for amplifying a signal from the magnetic head, and is always included in a signal from the magnetic head. That is, the system noise II is also included in the signal I at the time of tape sliding. Therefore, the magnitude of the sliding noise generated by the tape sliding can be obtained by subtracting the system noise II from the tape sliding signal I.

In the figure, since only noise is displayed as the signal I at the time of tape sliding, the signal I at the time of tape sliding is displayed.
The tape sliding noise III obtained by subtracting the system noise II from the above is represented by a hatched portion in the figure.

In a conventional magnetic head, as shown in FIG. 6 , the magnitude of tape sliding noise II is, for example, about 5 to 10 dB over the entire frequency range (30 Hz to 7.7 MHz) of an 8 mm video signal. It was large, and could reach nearly 10 dB especially in the frequency band of 4.0 to 9.0 MHz.

For this reason, there is a problem that the S / N ratio of the reproduced video signal from the magnetic tape is deteriorated, and the image quality or the sound quality is deteriorated.

Conventionally, in order to solve the above problems,
The above-described tape sliding noise was suppressed by forming only the vicinity of the gap in contact with the magnetic tape with single-crystal ferrite and forming the other portion with polycrystalline ferrite. However, there is a problem that the production cost is significantly increased as compared with the configuration using only single crystal ferrite.

The present invention has been made in view of the above points, and has as its object to provide a magnetic head which can be formed at a low cost only by using single crystal ferrite and which can reduce sliding noise as compared with the related art. .

[0016]

According to the first aspect of the present invention, a first core and a second core are formed so as to face each other with a non-magnetic glass member interposed therebetween. The gap and the surface of the first core and the second core on the gap forming position side with respect to the running direction of the magnetic tape running from the first core side to the second core side. The tape sliding surface is formed so as to be curved, and the tape sliding surface is provided on both sides of the tape sliding surface of the first core and the second core in the gap forming direction. A non-contact portion formed to have a step with respect to a moving surface;
A magnetic head comprising, on the tape sliding surface side of the core, a step formed to have a step with respect to the tape sliding surface and the non-contact portion, The distance between the end of the contact portion that is separated from the gap and the surface of the running magnetic tape is the second
By forming the non-contact portion so as to be larger than the distance between the end of the core of the non-contact portion separated from the gap and the surface of the running magnetic tape,
The step size of the non-contact portion with respect to the tape sliding surface is 1
The thickness was set to be not more than 00 μm.

[0017]

[0018]

[0019]

According to the structure of the first aspect, the distance between the end of the non-contact portion of the first core and the surface of the running magnetic tape is adjusted by the distance of the non-contact portion of the second core. It is formed so as to be longer than the distance between the end and the surface of the running magnetic tape, and the step size of the non-contact portion with respect to the tape sliding surface is 100 μm or less. Is smaller.

[0020]

[0021]

[0022]

1 is a perspective view of a magnetic head according to an embodiment of the present invention. In the figure,
4 and FIG. 5 are denoted by the same reference numerals, and description thereof will be omitted. 5a is a step processing surface corresponding to a non-contact portion. 4 and 5 is different from the tape running surface (the broken line T in the drawing) when the magnetic tape runs while sliding on the tape sliding surface 4.
(A surface indicated by) is configured so that the step processing surface 5a is inclined at a small angle θ.

That is, in FIG. 1, the step processing surfaces 5a formed on both sides of the tape sliding surface 4 in the direction of forming the gap 3 correspond to the gaps in the drum rotation direction (the direction D in the drawing) of the step processing surface 5a of the core 1a. 3 and the distance between the tape running surface and the tape running surface is the gap 3 in the direction opposite to the direction D of the step processing surface 5a in the core 1b.
Θ = 1 to 5 with respect to the tape running surface so as to be larger than the distance between the tape running surface and the end portion farthest from the tape.
It is formed at an inclination angle of about °.

As a result, the step processing depth B2 from the most protruding portion on the tape sliding surface 4 is calculated as follows: B2 = 100
It can be made shallower than before by setting it to about 30 (μm). In this case, especially if θ is about 2 °, B2
= 60 to 30 (μm), and the effects described later can be made more remarkable.

FIG. 3 is a diagram showing the effect of the magnetic head according to the present invention. 6, the same components as those of FIG. 6 are denoted by the same reference numerals, and the description thereof will be omitted. FIG.
(A), (B), (C) are step machining depths, respectively.
B2 = 80,40,30 (μm)
This is a result of measuring an electric signal output from the magnetic head with a spectrum analyzer, where Ia, Ib, and Ic are signals when the tape slides, and IIIa, IIIb, and IIIc are sliding noises.

As shown in FIGS. 3A, 3B and 3C, the inclination angle θ of the step processing surface 5a with respect to the tape running surface is appropriately set, and the step processing depth B2 is reduced. Video signal frequency domain (30 Hz to 10 MHZ
The sliding noise in z) can be reduced. For example, as shown in FIG. 3B, the step processing depth B2 =
In the case of 40 (μm), the magnitude of the sliding noise can be less than 5 dB at the maximum.

Further, since the shape of the magnetic head is different from the conventional one as described above, the material of the magnetic head can be all single crystal ferrite.
A magnetic head can be produced at a lower cost than a conventional magnetic head in which sliding noise is reduced by combining single crystal and polycrystalline ferrite.

The configuration in which the step processing surface 5a is inclined with respect to the tape running surface is effective only for the magnetic head provided with the step processing surface 6; The configuration is as follows.

[0029]

[0030]

[0031]

[0032]

[0033]

According to the first aspect of the present invention, since the step size of the non-contact portion with respect to the tape sliding surface is smaller than that of the conventional magnetic head, the video signal recorded on the magnetic tape can be reduced. In the frequency domain, sliding noise generated by sliding of the magnetic tape on the tape sliding surface is reduced, and the reproduced image quality and sound quality are improved .

According to the third aspect of the present invention, the portion corresponding to the step size in the conventional magnetic head can be considered to be quite small, so that the same effect as in the first aspect can be obtained.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an embodiment of a magnetic head according to the present invention.

FIG. 2 is a side view showing one embodiment of the magnetic head according to the present invention;

FIG. 3 is a diagram showing an effect of the magnetic head according to the present invention.

FIG. 4 is a diagram illustrating an example of a conventional magnetic head.

FIG. 5 is a three-view drawing showing an example of a conventional magnetic head.

FIG. 6 is a diagram showing a problem of a conventional magnetic head.

[Explanation of symbols]

1a, 1b, 1c Core 2 Non-magnetic glass member 3 Gap 4 Tape sliding surface 5, 5a, 5b Step processing surface 5c Chamfer processing portion 5d R shape processing portion 6 step processing surface B1, B2 step processing depth θ step processing surface Angle of inclination

Claims (1)

(57) [Scope of request for utility model registration] A gap formed by opposing a first core and a second core with a non-magnetic glass member interposed therebetween; and a gap formation of each of the first core and the second core. A tape sliding surface that is formed on the position side surface so as to be curved with respect to a traveling direction of the magnetic tape traveling from the first core side to the second core side, and that slides the magnetic tape; A non-contact portion formed on both sides of the tape sliding surface of the first core and the second core in the gap forming direction so as to have a step with respect to the tape sliding surface; A magnetic head having a step formed on the tape sliding surface side of the second core so as to have a step with respect to the tape sliding surface and the non-contact portion; Non-contact part The distance between the end of the magnetic core running away from the gap and the surface of the running magnetic tape is greater than the distance between the end of the second core separated from the gap of the non-contact portion and the surface of the running magnetic tape. A magnetic head having a configuration in which the non-contact portion is formed so as to be large so that a step size of the non-contact portion with respect to the tape sliding surface is 100 μm or less.