JPH04353622A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain the good recording and replay characteristic of the title recording medium by regulating the following: the film thickness of a rhombic vapor-desposited film; the residual flux desnity and the coercive force of the whole of a magnetic layer; and the stiffness of a lengthwise direction. CONSTITUTION:The title recording medium is constituted by laminating and forming the following on a nonmagnetic support body 1: a first ferromagnetic metal thin film 2 which is of rhombic pillar-shaped structure and which is composed of metal particles; and a second ferromagnetic metal thin film 3 which is of rhombic pillar-shaped structure and which is composed of metal particles whose long-axis direction is opposite to that of the first metal thin film 2. When the film thickness of the first metal thin film 2 is designated as delta1, the film thickness of the second metal thin film 3 is designated as delta2, the coercive force of the whole of a magnetic layer is designated as Hc, the residal flux density of the whole of the magnetic layer is designated as Br and the stiffness of a lengthwise direction is designated as St, they are set to values in formulae I to V. When the values of delta1, delta2, Hc, Br and St are regulated, it is possible to obtain the high C/N ratio and the high replay output of the recording medium in both the positive direction and the opposite direction without hardly causing a characteristic difference according to the sliding direction of a head when the title recording medium is used back and forth according to a nontracking system.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording medium suitable as a so-called non-tracking magnetic tape.

0002

2. Description of the Related Art The helical scan method, in which a head attached to a rotating drum is operated obliquely to the running direction of a magnetic tape, is used in video tape recorders (VTRs).
), is generally used as a recording method for digital audio tape recorders (DAT), and since this helical scan method is suitable for longer operation times, smaller size, and lower cost, it is also used in addition to VTRs and DATs, such as It is also expected to be used as a recording method for business-use digital memo machines that record audio from meetings and the like.

By the way, in a system employing this helical scan method, it is necessary for the head to accurately trace the recording track during reproduction. For this reason, for example, an AFT signal for tracking is recorded for each track along with recorded data, and during playback, the head detects this AFT signal to determine the positional error with respect to the track to be played back, and uses this error signal as a signal. Based on this, a tracking servo circuit controls the head position. Therefore, in a system that adopts such a helical scan method, it is necessary to install a complicated servo mechanism in addition to the recording/reproducing system, making it difficult to reduce the size further than the current size. It is considered that improvements are necessary for ultra-compact recording and reproducing devices such as digital memo machines for business use that require high performance.

[0004]Recently, therefore, a non-tracking method has been proposed as a recording/reproducing method that allows the servo mechanism to be simplified. In this non-tracking method, when reproducing data recorded by the helical scan method, the head is rotated at, for example, twice (or more than twice) the recording speed. This results in
Even without a complicated tracking servo mechanism, it is possible to completely detect the data recorded on the tape without missing any data.

That is, in the above-mentioned non-tracking method, when recording, as in the case of normal helical scan method recording, a rotating head (double azimuth The block track data is recorded diagonally with respect to the running direction of the tape. Then, during reproduction, the rotary head is rotated at, for example, twice the speed of recording. Then, the head traces the recording track so as to finely overlap it, so the recorded data is scanned with high density, and even if there is overlap, it will not be detected as missing. The detected data is then read into a DRAM (dynamic random read/write memory), rearranged based on the frame address and block address attached to the data, and restored as complete data.

Therefore, according to such a non-tracking method, since the head does not need to precisely trace the track, the conventional tracking servo circuit using AFT signals can be omitted, and the device can be made smaller and lighter. It becomes possible. In addition, in the normal helical scan method used in DAT etc., as mentioned above, the head needs to be placed faithfully to the track, so a highly accurate loading mechanism is essential. The tracking method eliminates the need for such a highly accurate loading mechanism. Therefore, we have created a tape guide shaft inside the tape cassette that has the functions of vertical guides and inclined pins that were conventionally located on the device side, and forms a tape path by simply protruding the rotating drum into the tape cassette without loading the tape. This makes it possible to realize a loading method, which further reduces the size of the device.
It becomes possible to improve the lightness.

By the way, in systems that employ this non-tracking method, since the non-tracking method is suitable for miniaturization and weight reduction, studies and development are proceeding toward ultra-compact recording and reproducing devices. For example, a tape cassette serving as a recording medium is assumed to have a size of about 30 x 21.5 x 5 mm, the size of a postage stamp, and a recording time of about 2 hours. For this reason, magnetic tape for non-tracking systems is required to have a high recording density so that good recording and playback can be achieved even when the cassette is of the size mentioned above and recording and playback is performed at the above recording time. For example, as such a recording medium, Co is deposited on a non-magnetic support.
Consideration has been given to employing a so-called oblique evaporation tape in which a ferromagnetic metal thin film is formed by obliquely evaporating -Ni alloy or the like.

As shown in FIG. 9, this obliquely vapor-deposited tape has a ferromagnetic metal thin film 3 having an orthorhombic columnar structure on a non-magnetic support 32.
1 is formed, and has the advantages of high saturation magnetization, high coercive force, and high output from high wavelength to short wavelength range, and has already been used as a recording medium for VTRs and DATs. This is something that has been put into practical use.

However, when the vapor-deposited tape is used in a non-tracking system, the following problems occur.

That is, in the vapor-deposited tape described above, when the head slides in the positive direction (direction of arrow a in the figure) with respect to the growth direction of the ferromagnetic metal thin film during recording and reproduction, the above-mentioned good recording and reproduction can be achieved. The characteristics are exhibited, but in the opposite direction to the growth direction of the ferromagnetic metal thin film (direction of arrow b in the figure).
When sliding in the forward direction, characteristics such as optimum recording current, phase characteristics, CN ratio, and output characteristics are inferior to those when sliding in the positive direction, and there is a drawback that sufficient recording and reproducing characteristics cannot be obtained. For this reason, systems in which the head slides only in one direction relative to the growth direction of the ferromagnetic metal thin film, such as a VTR,
Good recording and reproduction can be achieved with DAT, etc., but systems in which the head slides in both forward and reverse directions relative to the growth direction of the ferromagnetic metal thin film of the magnetic layer, for example, a magnetic tape that is divided into upper and lower parts in the width direction. In a reciprocating system in which recording and reproduction are performed individually, a problem arises in that the recording and reproduction characteristics deteriorate when the head slides in the opposite direction.

In a system using the above non-tracking method, the purpose is to downsize the cassette and to secure a recording time, so the above-mentioned reciprocating specification is adopted in order to secure a recording time. Therefore, the above-mentioned problems of the obliquely evaporated tape greatly affect its recording and reproducing performance.

[0012] Therefore, as an obliquely evaporated tape that solves these problems, an obliquely evaporated tape has been proposed in which the magnetic layer is constituted by two layers of obliquely evaporated films having different growth directions. In this two-layer obliquely vapor-deposited tape, the sliding direction of the head relative to the tape may be the same or different from the growth direction of the ferromagnetic metal thin film on the side that contacts the head (hereinafter referred to as , regarding the sliding direction of the head,
The case where the sliding direction is the same as the growth direction of the orthorhombic columnar structure of the ferromagnetic metal thin film on the side that contacts the head is called a positive direction, and the case where it is in a different direction is called a reverse direction. ) Since it exhibits similar phase characteristics and optimal recording current, it is attracting attention as a magnetic recording medium for non-tracking.

[0013]

[Problem to be solved by the invention] However, the above 2
For the layered obliquely vapor-deposited tape, differences in phase characteristics and optimum recording current due to head sliding direction are eliminated, but other characteristics, such as CN ratio and reproduction output, are affected by head sliding. It exhibits different characteristics depending on whether the direction is forward or reverse, and cannot be said to be fully satisfactory as a reciprocating magnetic tape.

The present invention has been proposed in view of the above-mentioned conventional circumstances, and provides a magnetic recording medium which has no characteristic difference depending on the sliding direction of the head and is suitable as a magnetic tape for a non-tracking system. The purpose is to

[0015]

[Means for solving the problem] When a conventional two-layer obliquely vapor-deposited tape is used back and forth, there is almost no difference in phase characteristics and optimum recording current depending on the sliding direction of the head, but there is a difference in CN ratio and playback output. The magnetic tape differs depending on whether the head slides in the forward direction or in the reverse direction, and cannot be said to be sufficient as a magnetic tape for a non-tracking system that requires reciprocating use. As a result of repeated studies by the inventors on the difference in CN ratio and output characteristics depending on the sliding direction of this head, we found that the difference in characteristics depending on the sliding direction of this head is due to the thickness of each ferromagnetic metal thin film and the overall magnetic layer. We have found that this problem can be solved by adjusting the coercive force and residual magnetic flux density.

The magnetic recording medium of the present invention was proposed based on such knowledge, and comprises a first ferromagnetic metal thin film having an orthorhombic columnar structure and a second ferromagnetic metal thin film on a nonmagnetic support. A magnetic layer is formed by sequentially laminating metal thin films,
The growth direction of the orthorhombic columnar structure of the first ferromagnetic metal thin film and the growth direction of the orthorhombic columnar structure of the second ferromagnetic metal thin film are opposite to each other, and the first ferromagnetic metal thin film When the thickness of the second ferromagnetic metal thin film is δ1, the coercive force of the entire magnetic layer is Hc, the residual magnetic flux density of the entire magnetic layer is Br, and the stiffness in the longitudinal direction is St, 1600Å≦δ1 +δ2 ≦2000Å1/3≦δ2
/δ1≦2/3 Hc≦1200Oe Hc×Br×(δ1 +δ2)≧50Oe・cm・G
It is characterized in that 2≦St≦10.

The magnetic recording medium of the present invention includes, for example, as shown in FIG. 1, a first ferromagnetic metal thin film 2 having an orthorhombic columnar structure on a nonmagnetic support 1; A second ferromagnetic metal thin film 3 whose growth direction of an orthorhombic columnar structure is opposite to that of the first ferromagnetic metal thin film is laminated.

The first ferromagnetic metal thin film 2 and the second ferromagnetic metal thin film 3 are formed by, for example, an oblique evaporation method.

First, in order to form the first ferromagnetic metal thin film 2 by the oblique vapor deposition method, as shown in FIG. 41, and the winding roll 50
Leave it so that it can be wound up. Then, as the drum 41 rotates, the non-magnetic support 42 is moved to r in the figure.
The metal material 43 filled in the crucible 44 to become a ferromagnetic metal thin film is evaporated while moving in the direction, and the vapor flow Y from the metal material 43 is directed against the normal direction X of the surface of the vapor non-magnetic support 42. Vapor deposition is performed while making the light incident at a certain angle of incidence θ.

At this time, a mask 4 is placed near the drum 41.
5 to regulate the incident angle θ of the vapor flow Y. As a result, vapor deposition on the non-magnetic support 1 is performed in a region up to the point where the surface of the non-magnetic support 1 is shielded by the mask 45, and the incident angle θ of the vapor flow Y is As the body 1 moves, the angle gradually changes from a high angle to a low angle, and reaches a minimum value at the position where the mask 45 is placed. The range of change of the incident angle θ of this vapor flow Y is
The angle is preferably 90 to 30 degrees. Also, mask 4
An O2 gas inlet is provided at the end of the support 5, and O2 gas is supplied to the surface of the vapor nonmagnetic support 1 from this O2 gas inlet. The supply of O2 gas improves the durability of the magnetic layer against oxidation, and at the same time, by adjusting the amount of O2 gas supplied at this time, the magnetic properties such as coercive force and residual magnetic flux density of the ferromagnetic metal thin film are controlled. be able to.

After forming the first ferromagnetic metal thin film 2 in this manner, a second ferromagnetic metal thin film 3 is formed on the first ferromagnetic metal thin film 2 by an oblique vapor deposition method. . At this time, in order to ensure that the growth direction is opposite to that of the first ferromagnetic metal thin film 2, the non-magnetic support 1 on which the first ferromagnetic metal thin film 2 is formed is wound. The take-up roll is now placed on the unwinding roll side. Then, the nonmagnetic support 1 is stretched over the outer circumferential surface 41a of the drum 41 and moved in the r direction, and vapor deposition is performed by the same method as described above. As a result, the non-magnetic support 1 travels in a direction opposite to the drum when the first ferromagnetic metal thin film 2 is formed. A second ferromagnetic metal thin film 3 having an orthorhombic columnar structure grown in the opposite direction is formed.

The metal materials constituting the first ferromagnetic metal thin film 2 and the second ferromagnetic metal thin film 3 are as follows:
There is no particular limitation, and for example, Co alone or a combination of two or more of Co, Ni, Ta, Cr, Pt, etc. can be used. This combination includes Co and Ni, Co and Pt, Co and Ta, and C.
Examples include o and Cr. Furthermore, as the non-magnetic support 1, any material that is normally used in this type of magnetic recording medium can be used.

Furthermore, the magnetic recording medium may be provided with an undercoat film, a back coat layer, or a top coat layer on the nonmagnetic support, if necessary. In this case, the materials for the undercoat film, backcoat layer, and topcoat layer are not particularly limited as long as they are normally used in this type of magnetic recording medium.

[0024] A magnetic recording medium having such a two-layered obliquely deposited film as a magnetic layer can be used reciprocatingly in the forward direction (direction of arrow A in FIG. 1) and in the reverse direction (direction of arrow B in FIG. 1). There is no difference in phase characteristics and optimum recording current, making it more suitable for reciprocating recording media than single-layer magnetic recording media. However, in order to make the above-mentioned obliquely deposited film equally good in terms of CN ratio and reproduction output characteristics in both the forward and reverse directions, it is necessary to Metal thin film 3
The film thickness δ2, the coercive force Hc of the entire magnetic layer, and the residual magnetic flux density Br need to be adjusted.

Therefore, in the magnetic recording medium of the present invention, when used back and forth by the non-tracking method,
In order to exhibit a high CN ratio and high reproduction output in both forward and reverse directions and obtain a good reproduction signal (a reproduction signal with an error rate of 1×10-2 or less), δ1, δ2,
It is assumed that Hc and Br are set so as to satisfy the following relationship. 1600Å≦δ1 +δ2 ≦2000Å1/3≦δ2
/δ1≦2/3 Hc≦1200Oe Hc×Br×(δ1 +δ2)≧50Oe・cm・G

[0026] Here, δ1 + δ2 is 1600 to 20
If it is not within the range of 00 Å, the error rate will be high and a good reproduced signal will not be obtained regardless of whether the head is sliding in the forward or reverse direction. Also, δ2
If /δ1 is less than 1/3, the error rate will be high when recording and reproducing by sliding the head in the forward direction, and if δ2 /δ1 is set to more than 2/3, the error rate will be high. , the error rate increases when the head slides in the A direction, and in either case, it is insufficient as a reciprocating magnetic tape.

On the other hand, Hc×Br×(δ1 +δ2) is set from the viewpoint of obtaining sufficient reproduction output by the non-tracking method. That is, it is generally known that the reproduction output of a ring head is approximately proportional to the in-plane coercive force, residual magnetic flux density, and thickness of the magnetic layer of the magnetic recording medium. In the non-tracking method, +3.5d is required to keep the error rate below 1x10-2.
It has been found through experiments that a reproduction output of B or more is required. To obtain a playback output of +3.5dB or more,
Hc x Br x (δ1 + δ2) is 50 Oe・cm・G
It is necessary that Hc×Br×(δ1 +
If δ2 ) is less than 50 Oe·cm·Ga, the reproduction output will be insufficient and the error rate will increase.

The coercive force Hc is set in consideration of the characteristics and current consumption of the head used in the non-tracking system. That is, in a non-tracking system, the recording current is usually set to 20 mA or less. Therefore, the magnetic recording medium must be capable of recording with a recording current of 20 mA or less. For this purpose, the coercive force Hc needs to be 1200 Oe or less, and if the coercive force Hc exceeds 1200 Oe, the recorded signal will be insufficient, leading to a reduction in reproduction output.

[0029] Furthermore, in the non-tracking method,
Normally, a non-loading system is used as the driving system. Therefore, in the magnetic recording medium of the present invention, the stiffness St in the longitudinal direction is set to 2 so that good recording and reproducing characteristics can be achieved even when a non-loading method is adopted.
As above, it is set to 10 or less. If St is less than 2, the magnetic recording medium loosens during running, creating a gap between the magnetic recording medium and the head, resulting in a spacing loss. In addition, if St exceeds 10,
Particularly in a head with a high curvature of the tape sliding contact portion, the length of contact between the head and the magnetic recording medium is short (less than 300 μm), making the contact between the gap portion and the magnetic recording medium unstable, and spacing loss also occurs.

[0030]

[Function] What is the first ferromagnetic metal thin film made of metal particles having an orthorhombic columnar structure on a non-magnetic support, and the metal particles of the first ferromagnetic metal thin film having an orthorhombic columnar structure with the long axis direction? In a magnetic recording medium in which a second ferromagnetic metal thin film made of metal particles in opposite directions is laminated, the thickness of the first ferromagnetic metal thin film, the thickness of the second ferromagnetic metal thin film, and the magnetic layer By regulating the overall coercive force and residual magnetic flux density, there is almost no difference in characteristics depending on the sliding direction of the head when using the non-tracking method back and forth, and a high CN ratio and high playback output can be obtained in both forward and reverse directions. . Further, when the stiffness in the longitudinal direction is set within a predetermined range, the contact length between the head and the magnetic recording medium becomes sufficient, spacing loss is suppressed, and good recording and reproduction is achieved.

[0031]

EXAMPLE A preferred example of the present invention will be explained based on experimental results.

Experimental Example 1 This experimental example is an example in which the film thickness δ1 +δ2 of the magnetic layer was studied.

[0033] In order to produce the obliquely vapor-deposited tape, first, an undercoat is applied to the non-magnetic support, and then Co80-Ni20
Using the alloy as a deposition source, vapor deposition is performed twice by changing the traveling direction of the non-magnetic support relative to the drum to form a first ferromagnetic metal thin film,
A second ferromagnetic metal thin film was formed. Next, a back coat layer and a top coat layer consisting of a lubricant were formed, the tape was cut to a predetermined width, and the tape was assembled into a cassette.

[0034] The vapor deposition was carried out by setting the range of change in the angle of incidence of the vapor flow to 90 to 45 degrees, and setting the O2 supply rate to 200 cc/min. At this time, the film thicknesses δ1 and δ2 of the ferromagnetic metal thin films were adjusted by controlling the beam current supplied to the crucible to keep the amount of vapor flow constant and changing the moving speed of the tape. In this example, the thickness of the deposited film was determined by the tape moving speed of 14 m.
/min, it was 2000 Å.

By such a method, various obliquely vapor-deposited tapes were produced by varying the film thickness δ1 + δ2 within a range where δ1 :δ2 was 1:0.5. Then, recording and reproduction were performed on the various obliquely vapor-deposited tapes produced in both forward and reverse directions, and the error rate was measured.

Table 1 shows the thickness δ1 of the first ferromagnetic metal thin film and the thickness δ2 of the second ferromagnetic metal thin film of each obliquely evaporated tape.
, the thickness δ1+δ2 of the entire magnetic layer, the coercive force Hc, the residual magnetic flux density Br, and the error rate during reproduction. Further, FIG. 3 shows the relationship between the thickness δ1 +δ2 of the magnetic layer and the error rate.

[Table 1]

As can be seen from FIG. 3, with the obliquely evaporated tape, the change in error rate due to the thickness of the magnetic layer has a minimum value regardless of whether the head slides in the forward or reverse direction. It is represented by a nearly hyperbola. Here, in a non-tracking system, in order to obtain a good reproduction signal, it is necessary that the error rate is 1 x 10-2 or less, and the magnetic The thickness of the layer is 1600-2000 Å. Therefore, it was shown from this that in order to obtain an obliquely vapor-deposited tape that can be applied as a magnetic tape for non-tracking system, it is suitable to set the film thickness δ1 +δ2 of the magnetic layer to 1600 to 2000 Å.

Experimental Example 2 This experimental example is an example in which the film thickness ratio δ2/δ1 was studied. Using the same method as in Experimental Example 1, δ2 /δ1 was adjusted in a range where the thickness of the magnetic layer δ1 + δ2 was 1800 Å.
Various obliquely evaporated tapes were produced by changing the . and,
Recording and reproduction were performed on the various obliquely evaporated tapes produced in both forward and reverse directions, and the error rate was measured.

Table 2 shows the thickness δ1 of the first ferromagnetic metal thin film and the thickness δ2 of the second ferromagnetic metal thin film of each obliquely evaporated tape.
, film thickness ratio δ2/δ1, coercive force Hc, residual magnetic flux density Br, and error rate during reproduction. Further, FIG. 4 shows the relationship between the film thickness δ1 of the first ferromagnetic metal thin film and the error rate.

[Table 2]

As can be seen from FIG. 4, in the case of the obliquely evaporated tape, when the sliding direction of the head is in the positive direction, the error rate increases as the film thickness δ1 of the first ferromagnetic metal thin film increases. In contrast, in the opposite direction, the smaller the film thickness δ1 is, the higher the error rate is, and as the film thickness δ1 increases, the error rate decreases. Here, the film thickness δ1 at which the error rate is 1×10 −2 or less in both forward and reverse directions is 1080 to 1350 Å. Therefore, from this, in order to obtain an obliquely evaporated tape that can be applied as a magnetic tape for a non-tracking system, the film thickness ratio δ2
It was shown that /δ1 is preferably set to 1/3 or more and 2/3 or less.

Experimental Example 3 In this experimental example, the energy product Hc×Br×(δ1 +δ2
) and coercive force Hc. In addition to Co80-Ni20, Co1 is used as a deposition source during vapor deposition.
Various obliquely evaporated tapes were produced in the same manner as in Example 1, except that the residual magnetic flux density Br and the coercive force Hc were adjusted by changing the amount of O2 supplied. and,
Recording and reproduction were performed in both forward and reverse directions for the various obliquely evaporated tapes produced, and the reproduction output and optimum recording current were measured.

Table 3 shows O2 during vapor deposition of each oblique vapor deposition tape.
The supply amount, coercive force Hc, residual magnetic flux density Br, energy product Hc×Br×(δ1 +δ2), optimum recording current, and reproduction output are shown. In addition, Fig. 5 shows the energy product Hc×Br×
The relationship between (δ1 +δ2) and reproduction output is shown in FIG. 6, and the relationship between coercive force Hc and optimum recording current is shown in FIG. Note that the reproduction output shown in FIG. 5 is a ratio with that of a metal-coated magnetic tape, and the optimum recording current shown in FIG. 6 is expressed in dB with 20 mA as a reference.

[Table 3]

As can be seen from FIG. 5, in the case of the obliquely evaporated tape, the reproduction output increases as the energy product increases in both the forward and reverse directions. In the non-tracking method, in order to suppress the error rate to 1x10-2 or less, the playback output must be +3.5 dB or more, and the playback output is +3.5 dB for both forward and reverse playback.
．． The energy product of 5 dB or more was 50 Oe or more. Therefore, in order to obtain an orthogonal evaporated tape that can be applied as a magnetic tape for non-tracking systems,
Coercive force Hc and residual magnetic flux density Br are Hc×Br×(δ1
+δ2)≧50Oe was shown to be suitable.

Furthermore, as can be seen from FIG. 6, 2 is the recording current that can be used in the non-tracking system.
The optimum recording current is 0 mA or less when the coercive force Hc is 1.
This is a case of 200 Oe or less. Therefore, from this, in order to obtain an obliquely evaporated tape that can be applied as a magnetic tape for non-tracking method, the coercive force Hc is 1200.
It has been shown that it is preferable to set it to below Oe.

The measuring equipment used to measure the electromagnetic conversion characteristics and magnetic characteristics in each experimental example is shown below. Magnetic properties (coercive force, residual magnetic flux density) Measuring device: Vibrating sample magnetometer Electromagnetic conversion characteristics (optimal recording current, playback output, error rate) Measuring device: Sony Corporation, product name NT-1
(Modified product) Head specifications
Type/MIG (metal in gap) head
Material: Single crystal ferrite (MnZn)
(Gap part is Sendust) Gap length: 0.22μm Recording wavelength
0.67μm Sampling frequency 32kHz Quantization bit number
12bit broken line

Experimental Example 4 This experimental example is an example in which longitudinal stiffness St was investigated. Various obliquely evaporated tapes were produced in the same manner as in Experimental Example 1, except that the materials and film thicknesses shown in Table 1 were used as nonmagnetic supports, and the stiffness St was varied. Then, the contact length of the head was measured for the various obliquely vapor-deposited tapes produced. Table 4 shows the stiffness St of each obliquely evaporated tape and the length of contact between the tape and the head.

[Table 4]

The stiffness St of the tape was measured by measuring two strains using a strain gauge. In addition, to measure the contact length between the tape and the head, use a spacing measurement device using optical interferometry that uses a glass head with a prism, and measure the distance between two points where the measured spacing changes rapidly. It was done by At this time, the glass head used had a width of 87 μm, a protrusion of 28 μm, and a radius of curvature of 6.8 mm.

As can be seen from Table 4, in the case of the obliquely vapor-deposited tape with St of 1.2, the head 7 as shown in FIG.
The tape 71 was lifted in the gap 73 of No. 2, and the length per head could not be measured. In addition, for tapes with St of 11.6 and 19.1, tape 7
1 does not completely contact the curved surface of the head 72, and a sufficient length per head cannot be obtained. Therefore, in order to ensure sufficient contact length for the head and suppress spacing loss in the obliquely evaporated tape, it was shown that it is suitable to set the stiffness St in the range of 2 to 10. .

[0049]

Effects of the Invention As is clear from the above description, the magnetic recording medium of the present invention has two obliquely deposited films having different growth directions as magnetic layers. The film thickness, residual magnetic flux density and coercive force of the entire magnetic layer, and stiffness in the longitudinal direction are regulated, so even when used back and forth in non-tracking and non-loading methods, the phase characteristics, optimal recording current, CN ratio, There is no difference in the reproduction output between forward and reverse directions, spacing loss is suppressed, and good recording and reproduction characteristics can be obtained in either case. Therefore, according to the present invention, it is possible to realize a magnetic tape having sufficient characteristics as a magnetic tape for a non-tracking system, and it is possible to improve the practicality and performance of a non-tracking system.

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view showing a configuration example of a magnetic recording medium of the present invention.

FIG. 2 is a schematic cross-sectional view of a main part of a vapor deposition apparatus used for vapor deposition of a ferromagnetic metal thin film.

FIG. 3 is a characteristic diagram showing the relationship between the thickness δ1 +δ2 of the magnetic layer and the error rate.

FIG. 4 is a characteristic diagram showing the relationship between the film thickness ratio δ2/δ1 and the error rate.

[Figure 5] Energy product Hc x Br x (δ1 + δ2)
FIG. 3 is a characteristic diagram showing the relationship between the output power and the reproduction output.

FIG. 6 is a characteristic diagram showing the relationship between coercive force Hc and optimum recording current.

FIG. 7 is a schematic diagram showing how the obliquely evaporated tape is lifted from the head.

FIG. 8 is a schematic diagram showing how the obliquely evaporated tape does not completely contact the curved surface of the head.

FIG. 9 is a schematic cross-sectional view showing the structure of a conventional oblique vapor deposition tape.

[Explanation of symbols]

1...Nonmagnetic support 2...First ferromagnetic metal thin film 3...Second ferromagnetic metal thin film

Claims (1)

[Claims] 1. A magnetic layer is formed in which a first ferromagnetic metal thin film and a second ferromagnetic metal thin film having an orthorhombic columnar structure are sequentially laminated on a non-magnetic support, The growth direction of the orthorhombic columnar structure of the magnetic metal thin film and the growth direction of the orthorhombic columnar structure of the second ferromagnetic metal thin film are opposite to each other, and the film thickness of the first ferromagnetic metal thin film is set to δ1.
, the thickness of the second ferromagnetic metal thin film is δ2, the coercive force of the entire magnetic layer is Hc, and the residual magnetic flux density of the entire magnetic layer is Br.
, when the stiffness in the longitudinal direction is St, 160
0Å≦δ1 +δ2 ≦2000Å1/3≦δ2 /δ
1≦2/3 Hc≦1200Oe Hc×Br×(δ1 +δ2)≧50Oe・cm・G
A magnetic recording medium characterized in that 2≦St≦10.