JP2885315B2 - Magnetic recording media - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a direction of relative movement of a magnetic head with respect to a magnetic recording medium during recording / reproducing (same as a relative (target) traveling direction).
The present invention relates to a magnetic recording medium for recording a low-frequency conversion chroma video signal in which is set in one direction. [Prior art] For a so-called evaporated magnetic tape having a magnetic layer provided on a non-magnetic substrate by an oblique evaporation method, as an appropriate recording / reproducing method, a magnetic columnar crystal for forming the magnetic layer has been used. A recording / reproducing method (Japanese Patent Laid-Open No. 57-92401) has been proposed in which a magnetic head travels in the same direction as the tilt direction of the magnetic head. [Problems to be Solved by the Invention] However, when the above-mentioned conventional method is applied,
Although the S / N of the luminance signal is good, there is a problem that the S / N of the color signal is reduced. SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems in the prior art and to provide a magnetic recording medium having sufficient characteristics for both video S / N and color S / N. [Means for Solving the Problems] The above object is to provide a plurality of obliquely deposited magnetic layers provided on a non-magnetic substrate, the inclination direction of crystal columns of the uppermost magnetic layer and the magnetic layers other than the uppermost layer. This can be achieved by making the inclination direction of the crystal columns different from each other and making the thickness of the uppermost magnetic layer smaller than the thickness of the magnetic layers other than the uppermost layer. [Operation] The inventors have conducted intensive studies on a magnetic recording medium used for recording a video signal of a low-frequency conversion chroma system, and as a result,
The S / N of the luminance signal in the high frequency range is better when the magnetic head is run in the forward direction with respect to the tilt direction of the crystal columns of the magnetic layer formed by oblique evaporation, and the color signal in the low frequency range is better. Conversely, the S / N ratio was better when the magnetic head was run in the direction opposite to the direction of inclination of the crystal columns of the magnetic layer. For this reason, the magnetic layer is composed of a plurality of layers for recording a luminance signal and a layer for recording other signals (for example, color signals), and the inclination direction of the uppermost crystal column is set to the direction of the magnetic head. The relative traveling direction, that is, the uppermost layer is used for recording a luminance signal, and the inclination direction of the crystal columns of the layers other than the uppermost layer is set to the direction opposite to the relative traveling direction of the magnetic head, that is, By using layers other than the top layer for recording color signals, etc., video S / N and color S
A result was obtained that a magnetic recording medium having good characteristics for both / N could be obtained. The thickness d of the uppermost magnetic layer used for recording the luminance signal, to the recording wavelength lambda _gamma luminance signal, lambda _gamma
If it is less than / 15, the luminance signal cannot be recorded enough,
In addition, if λ _γ / 5 or more, even the color signal subjected to the low-frequency conversion is written to the layer, and the color S / N is reduced. Therefore, λ _γ / 15 <d <λ _γ / 5 It would be desirable. On the other hand, the thickness of the magnetic layers other than the outermost layer needs to be larger than the thickness of the uppermost magnetic layer because, for example, a color signal is converted to a low band. EXAMPLES Hereinafter, the magnetic recording medium according to the present invention will be described with reference to examples. Example 1 FIG. 1 is an enlarged sectional view showing the structure of a magnetic recording medium according to the present invention, in which a substrate 1, a lower magnetic layer 2, an upper magnetic layer 3,
This indicates that the back coat layer 4 is formed. In the present embodiment, a 10 μm-thick polyester film is used as the substrate 1, a lower magnetic layer 2 having a thickness of 1500 mm is formed on the substrate by oblique evaporation, and the lower layer is formed on the lower layer. The upper magnetic layer 3 having a thickness of 1000 mm was formed by oblique evaporation from a direction different from that of the above, and a back coat layer 4 having a thickness of 1 μm was applied on the back surface of the base to produce a magnetic tape. Example 2 The thickness of the upper magnetic layer 3 in Example 1 was set to 750 °.
A magnetic tape was manufactured in the same manner as in Example 1 except for the above. Reference Example 1 The thickness of the upper magnetic layer 3 in Example 1 was 400
A magnetic tape was manufactured in the same manner as in Example 1 except for the above. Comparative Example 1 A magnetic layer having a thickness of 2500 ° was formed on a polyester film having a thickness of 10 μm by an oblique evaporation method to produce a magnetic tape. For the above four types of samples, a sender string head having a gap length of 0.35 μm and a track width of 20 μm was used, and the relative running directions of the heads were changed to those of the upper magnetic layer of Examples 1, 2 and Reference Example 1 and Comparative Example 1. 8mmV as crystal column tilt direction
Video S / N (signal recording wavelength 0.75 μm) and color S / N were measured using TR, and the results shown in Table 1 were obtained. Since Comparative Example 1 was a single layer, it was regarded as an upper magnetic layer. The data shown in Examples 1-2 and Reference Example 1 and Comparative Example 1 of Table 1, the video S / N by using the 8 mm VTR (luminance signal recording wavelength lambda _gamma 0.75 .mu.m: average value) and the color S / N It shows the relative value obtained by measuring and based on the value (0) of Comparative Example 1. Here, Example 1 is a luminance signal recording wavelength lambda _gamma 0.75 .mu.m
The thickness of the upper magnetic layer is 400 °, which indicates the two-layer structure of the present invention. The condition described in the claims of the present invention (λ _γ / 15 <d <λ _γ / 5) Is outside the range
The video S / N (dB) shows a bad value of -1.0. However, the color S / N (dB) is excellent at +3.5. Then, Examples 1 and 2 are within the range satisfying the condition _{(λ γ / 15 <d <} λ γ / 5) of the present invention, video S / N (dB)
Are +2.0, +1.0, and color S / N (dB) is +3.5, +3.0
And, both show excellent values, video tapes within the range of the conditions of the present invention, both video S / N and color S / N,
It can be seen that the sample of Comparative Example 1 shows a remarkable improvement. Next, a tape-shaped magnetic recording medium shown in FIG. 1 was produced in the same manner as in Example 1 above. First, a lower magnetic layer 2 is formed to a thickness of 3000 ° on a substrate 1 made of a polyester film by an oblique vapor deposition method, and then is formed thereon by an oblique vapor deposition method from a direction different from that of the lower magnetic layer 2. ,
The upper magnetic layer 3, which is the uppermost layer, is set to 1700 ° (Example 3), 13
In Comparative Example 2, only the upper magnetic layer 2 was formed to have a thickness of 4500 ° to form a single layer of 00 ° (Example 4) and 700 ° (Reference Example 2). Other manufacturing conditions are the same as in the first embodiment. The prepared tape-shaped magnetic recording medium is slit into a predetermined width, assembled into a VHS video cassette, and using a video deck, the crystal column inclination direction of the uppermost magnetic layer is set to the relative running direction of the magnetic head. None, video S / N and color S / N were measured. Table 2 shows the results. Incidentally, the luminance signal recording wavelength lambda _gamma with 1.3 .mu.m (mean value). In the Table 2, Example 2 is a 1.3μm luminance signal recording wavelength lambda _gamma, the thickness of the lower magnetic layer is 3000 Å, the thickness of the upper magnetic layer is shown and 700 Å, a two-layer structure of the present invention Since the thickness of the upper magnetic layer is 700 °, the condition (λ _γ / 15 <d <λ _γ /
5) is out of the range, and the video S / N (dB) shows a bad value of -1.0. However, the color S / N (dB) is excellent at +2.5. Examples 3 and 4 which satisfies _{λ γ / 15 <d <λ} γ / 5 of the conditions of the present invention, a video S / N (dB) is + 1.5, + 1.0, the color S / N (dB) Are +3.0 and +2.5, which are excellent values, and the video tapes within the range of the conditions of the present invention are remarkably different from the sample of Comparative Example 2 in both the video S / N and the color S / N. It can be seen that it shows a significant improvement. [Effects of the Invention] As described above, the magnetic recording medium has the configuration according to the present invention, that is, a plurality of obliquely deposited magnetic layers provided on a non-magnetic substrate, and the crystal columns of the uppermost magnetic layer (This direction is defined as the forward direction of the relative running direction of the magnetic head) and the inclination direction of the crystal columns of the magnetic layers other than the uppermost layer are different from each other, and the thickness of the uppermost magnetic layer is thinner than the thickness of the top layer other than the layer, further, lambda _gamma / 15 of the top layer of thickness d with respect to the recording wavelength lambda _gamma luminance signal <d <
By setting the thickness to satisfy the condition of _λγ / 5, it was possible to provide a magnetic recording medium having sufficient characteristics for both video S / N and color S / N.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an enlarged sectional view showing an embodiment of a magnetic tape according to the present invention (an arrow indicates a relative running direction of a magnetic head). DESCRIPTION OF SYMBOLS 1 ... Substrate 2 ... Lower magnetic layer 3 ... Upper magnetic layer 4 ... Back coat layer

   ────────────────────────────────────────────────── ─── Continuation of front page    (72) Inventor Hideaki Niimi               Hitachi, 1-88 Ushitora, Ibaraki-shi, Osaka               Maxell, Inc. (72) Inventor Kunio Wakai               Hitachi, 1-88 Ushitora, Ibaraki-shi, Osaka               Maxell, Inc.                (56) References JP-A-57-92402 (JP, A)

Claims (1)

(57) [Claims] A magnetic recording medium for low-frequency conversion video signal recording in which the relative traveling direction of the magnetic head with respect to the magnetic recording medium during recording / reproduction is set to one direction, the magnetic recording medium is formed by oblique evaporation on a non-magnetic substrate. The inclination direction of the crystal columns of the uppermost magnetic layer is different from the inclination direction of the crystal columns of the magnetic layers other than the uppermost layer, and the uppermost magnetic layer is mainly In addition to recording the luminance signal, the inclination direction of the crystal columns of the uppermost magnetic layer is set as the relative running direction of the magnetic head, and the thickness of the uppermost magnetic layer is mainly used for recording other than the luminance signal. No thinner than the thickness of the uppermost magnetic layer other than the magnetic layer was, and the thickness of the uppermost magnetic layer (d), λ γ _/ 15 with respect to the recording wavelength lambda _gamma luminance signal <d <lambda a magnetic recording medium having a value satisfying a condition of _γ / 5. .