JPH0159643B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic recording/reproducing device such as a video tape recorder (VTR), which uses a recording medium having a magnetic vapor-deposited thin film layer and a magnetic head made of single crystal ferrite, thereby achieving an improved performance that is far superior to conventional devices. This paper proposes a compact and high-performance magnetic recording/reproducing device.

In recent years, there has been an extremely strong demand for higher recording densities in the field of magnetic recording, and in order to meet this demand, recording media have been made to have high coercive force (HC) and residual magnetic flux density (Br), and at the same time, magnetic heads have been made to have high sensitivity. Various measures have been taken to achieve this goal. for example
For videotape in VTR, γ−Fe ₂ O ₃ (Hc=
300Oe, Br=900 Gauss) to _CrO2 (Hc=510Oe,
Br = 1300 Gauss), and further to Co-based iron oxide tape (Hc = 670 Oe, Br = 1400 Gauss), and in video heads, optimization of the core material, structure, and manufacturing method has made it particularly short. Sensitivity in the wavelength region has improved dramatically. In particular, in the case of single-crystal ferrite, which has recently been widely used in household VTRs, etc., the characteristics of the head-tape system are greatly influenced by the crystal orientation and how the magnetic core is arranged.

Conventionally, as shown in Fig. 1, the head gap 3
The sliding surfaces 2, 2a of the head cores 1, 1a made of two single-crystal ferrite sandwiching each tape are {211} planes (here, {211} planes are 211, 121, 112,
211, 211, 211, 121, 121, 121, 11
2, 112, 112, 211, 211, 211, 1
21, 121, 121, 112, 112, 11
It is a general term for 24 types of surfaces: 2, 211, 121, and 112. ), and the head gap forming surfaces 5, 5a are {111} planes (here, {111} planes are
111, 111, 111, 111, 111, 111,
111, 111 is a general term for eight types of surfaces. ), and the {110} plane of the main magnetic path configuration plane (here, the {110} plane means 110, 101,
011, 110, 101, 101, 110, 110, 0
It is a general term for 12 types of faces: 11, 011, 101, and 011. ) in the <110> axis (here, <110>
The axes are 110, 101, 011, 110, 101, 101, 1
10, 110, 011, 011, 101, 011 12
It is a general term for the axis of a street. ) is symmetrical with respect to the gap forming surfaces 5, 5a on the left and right cores 1, 1a, and is shaped like a "C" so that the angle θ between the gap and the sliding direction with the tape is 35.3°. The best characteristics are obtained by this arrangement.

Recent home-use VTRs use Co-based iron oxide tape and the above-mentioned high-sensitivity video heads to achieve a minimum wavelength of about 1 μm, making them compact and high-performance.
I'm getting a VTR. However, the wave of higher density in this field does not stop there; there is also a demand for further reduction in weight and size, and ultimately there is a desire for integration with a camera. In order to meet this demand, it is first necessary to reduce the diameter of the cylinder that houses the video head, and as a result, the shortest wavelength is, for example, 0.6 μm.
It is necessary to put this degree into practical use. It is also necessary to increase the area density by narrowing the track. As a result, the reproduction output decreases significantly, and current tape-head systems cannot cope with this problem. Therefore, even higher
There is an urgent need to develop magnetic tapes with high Hc and high Br, and the practical use of alloy powder tapes is being considered as one of them. This tape usually has an Hc of 1000~
Ultra-high density recording is possible because the Br of about 1400 Oe is about 2000 to 3500 Gauss, but with ferrite heads, the core saturates during recording and cannot fully demonstrate its characteristics. Although recording problems can be solved by using a head with a metal ferromagnetic material as the core material, it is currently inferior to a ferrite head in terms of playback efficiency, wear resistance, ease of manufacture, cost, etc. be.

In contrast, what we propose is to use a magnetic thin film tape for recording and reproduction with a ferrite head. Thin film tape is a thin plastic film of several micrometers or 10-odd micrometers.
A thin film of several 100 Å to several 1000 Å is created by vacuum evaporating or sputtering a magnetic material such as Co, Co-Ni, Co-Cr, or Fe based on a base.
[Oe] About Br6000 [G] has been obtained.

In this way, the magnetic thin film tape has both Hc and Br values that are sufficient to respond to the shortening of wavelength due to the above-mentioned background, and at the same time, since the magnetic layer is extremely thin, sufficient recording is possible even with a ferrite head, and its high performance characteristics can be achieved. It can be demonstrated.

On the other hand, since the surface properties of magnetic thin films are extremely smooth,
There is almost no problem with head wear, but because the head is smooth, a complicated surface roughness phenomenon occurs on the head surface.

Figure 2a shows a Co-Ni head formed by vacuum evaporation in contrast to the conventional head shown in Figure 1.
A magnetic recording medium with a magnetic layer of the system at a relative speed of 3.75
This shows the surface roughness of the head when it is slid at m/sec for one hour, and Figure 2b also shows the roughness of the head surface of the type where θ=90°. . 3a shows the surface roughness of the sliding surface 2 of the tape inlet core 1 of the head shown in FIG. 2a, and FIG. 3b shows the surface roughness of the tape outlet core 1 of the head shown in FIG. 2a. ' indicates the surface roughness of the sliding surface 2a,
Figure 3c shows the surface roughness of the sliding surface 2a of the tape exit core 1' of the head shown in Figure 2b. Each surface roughness is measured in a direction perpendicular to the sliding direction of the recording medium. are doing. In the case of Figure 3b, the surface roughness is approximately
It is 400 to 500 Å, which is approximately one order of magnitude larger than the cases shown in Figures 3a and 3c. In this way, the phenomenon of surface roughness is the first
It has a correlation with the inclination θ of <110 axis> in the figure, and this relationship is shown in FIG. When θ = 0°, 90°, or around these angles, surface roughness does not occur regardless of the running direction of the tape, but in the range of 20 to 70°, surface roughness occurs although there are differences in conditions, and as described above. It varies greatly depending on how the <110 axis> intersects with the tape running direction. When such surface roughness occurs, spacing loss occurs between the head gap and the magnetic recording medium due to the unevenness caused by the surface roughness in the head gap, which significantly degrades the short wavelength output and changes the envelope shape of the head output. A problem arises in that the signal to noise ratio is also affected and the signal-to-noise ratio deteriorates.

Types with θ = 0° and 90° do not cause such a surface roughening phenomenon, but types with θ = 0° have poor recording and reproducing sensitivity and problems will arise in terms of practical use if wavelengths are further shortened. Therefore, when using a magnetic thin film tape as a recording medium, the θ=90° type head, that is, the sliding surface is the {110} plane, and the gap forming surface is the {100} plane (here, the {100} plane is 100, 010, 001, 100,
It is a general term for the six types of faces 010 and 001. ) can fully demonstrate its high performance characteristics by recording and reproducing data using a single-crystal ferrite head constructed of ferrite heads.

It has been known that when a Co-based iron oxide tape is used as a recording medium, the wear of ferrite crystals differs depending on the crystal orientation, but in this case, the surface roughness does not change substantially. figure,
Throughout the entire head surface that slides against the recording medium,
Only a phenomenon in which wear is accelerated almost uniformly occurs, and a complicated surface roughening phenomenon in which the surface roughness changes significantly does not occur. In other words, if the head surface is not rough and wear progresses uniformly and gradually over almost the entire surface, the head surface will not become rough as it would when using a magnetic thin film formed by vapor deposition. No major changes or deterioration in characteristics occur.

From a friction point of view, wear resistance and surface roughness resistance do not necessarily match, and it cannot be concluded that the surface roughness is low based on the viewpoint that the wear is low.

The above-mentioned phenomenon in which surface roughness differs depending on the crystal orientation of single-crystal ferrite occurs when a single-crystal ferrite is combined with a magnetic recording medium in which a magnetic thin film is formed by vapor deposition. This is a new phenomenon that is different from wear.
The present invention was made based on the discovery of this phenomenon, and is based on the combination of a magnetic recording medium in which a magnetic thin film is formed on a nonmagnetic substrate by vapor deposition, and a single crystal ferrite magnetic head, which makes contact with the magnetic recording medium.・The sliding surface consists of a {110} plane or a crystal plane inclined at an angle of 20° to the {110} plane, and the void forming plane is a {100} plane or an angle of 20° to the {100} plane. By performing recording and reproducing using a magnetic head composed of inclined crystal planes, it has been possible to provide a magnetic recording and reproducing device that can fully exhibit its high performance characteristics over a long period of time.

FIG. 5 shows the relationship between the recording wavelength and the relative head output, and curve A shows the relationship between the single crystal ferrite head (the θ=90° type head) according to the present invention and the Co
-Curve B shows the output characteristics of a recording/reproducing device obtained by combining a magnetic recording medium with a Ni-based magnetic thin film formed by vapor deposition.
This figure shows the output characteristics of a recording/reproducing device obtained by combining a Co-based iron oxide tape and a single-crystal ferrite head (head with θ = 35.3°).
From the figure, it can be seen that the recording/reproducing device according to the present invention can obtain superior output characteristics, especially in the short wavelength region, compared to the conventional device. Therefore,
Sufficient high-quality images can be obtained even if the cylinder diameter is significantly reduced. The output characteristics of the recording/reproducing apparatus of the present invention do not deteriorate at all even when used for a long time.

[Brief explanation of drawings]

Fig. 1 is a side view showing the configuration of a conventional magnetic head using single crystal ferrite, Fig. 2a is a micrograph showing the roughness of the tape sliding surface of the magnetic head shown in Fig. 1, and b is a photomicrograph showing the roughness of the tape sliding surface of the magnetic head shown in Fig. Micrographs showing the surface roughness of the tape sliding surface of the magnetic head of the invention; FIGS. 3a, b, and c are measurement views of the surface roughness of the magnetic head core in FIGS. FIG. 5 is a diagram showing the relationship between the inclination θ of the <110 axis> with respect to the sliding direction and surface roughness, and FIG. 5 is a diagram showing the relationship between the recording wavelength and relative head output of the magnetic head according to the present invention and the conventional magnetic head. 1, 1a... Head core, 2, 2a... Sliding surface, 3... Head gap, 5... Gap forming surface.

Claims (1)

[Claims] 1. Using a magnetic recording medium in which a magnetic thin film is formed by vapor deposition on a non-magnetic substrate, the surface that contacts and slides on the magnetic recording medium is a {110} plane or within a range of 20° to the {110} plane. Recording and reproduction is performed using a single crystal ferrite magnetic head consisting of an inclined crystal plane, and the void forming plane is a {100} plane or a crystal plane inclined within a range of 20° with respect to the {100} plane. magnetic recording and reproducing device.