JPH0695419A - Thermo-magnetic recording medium - Google Patents

Abstract

PURPOSE:To provide a thermo-magnetic recording medium for perpendicular recording having such magnetic characteristics as sufficiently high residual magnetic flux density and high coercive force and fit for high density recording. CONSTITUTION:A magnetic film 20 made of a thin Nd-Fe-B alloy film is formed on a nonmagnetic substrate 10 capable of withstanding heat treatment for forming the magnetic film 20 to obtain the objective thermo-magnetic recording medium. The compsn. of the magnetic film is represented by a formula (NdxFe100-x)100-yBy (where 10<=x<=25 and y>=10) and the substrate 10 is stainless steel or copper foil capable of withstanding heat treatment at >=460 deg.C.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermomagnetic recording medium suitable for forming a magnetic latent image.

[0002]

2. Description of the Related Art Conventionally, there is known a technique of forming a magnetic latent image on a magnetic recording medium and developing it by magnetic means to obtain a visible image. As a means for forming the magnetic latent image, there is a means for locally applying a large signal magnetic field to a magnetic medium by a magnetic head to magnetize the medium and use the residual magnetization as a latent image.
Further, as another means for forming a magnetic latent image, there is one utilizing the thermal remanent magnetization effect.

This thermal remanent magnetization effect is a characteristic that a certain type of magnetic material exhibits a large remanent magnetization when heated from a demagnetized state while applying a weak magnetic field in a certain direction and then returned to room temperature, and is uniform. It is possible to form a magnetic latent image by locally heating under a weak magnetic field. The magnetic recording medium used for thermomagnetic printing is a thermomagnetic recording medium, and utilizes the magnetic latent image due to the above-mentioned thermal remanent magnetization effect.

A conventional thermomagnetic printer for printing by thermomagnetic printing will be described below. For the thermo-magnetic printer using the thermo-magnetic printing, for example, "Non-impact printing CMC"
Chapter 15 Magnetography Printer Shunji Imamura
p. p. 159-168 1986 ".

FIG. 4 is a printing process diagram of a conventional thermomagnetic printer. In FIG. 4, 1 is a recording magnetic drum, 2
Is demagnetizing means, 3 is magnetic recording means, 4 is developing means, 5 is transferring means, 6 is fixing means, and 7 is cleaning means.
The recording magnetic drum 1 rotates in the direction of arrow A. On the surface of the recording magnetic drum 1, a CrO ₂ thin film or the like is formed as a thermomagnetic recording medium for forming a magnetic latent image. Then, the demagnetizing means 2, the magnetic recording means 3, the developing means 4, the transfer means 5, the fixing means 6 and the cleaning means 7 are arranged in this order around the recording magnetic drum 1, and as the recording magnetic drum 1 rotates. The printing process is performed by sequentially processing the thermomagnetic recording medium of the recording magnetic drum 1.

The printing process will be described below. (1) First, the degaussing means 2 demagnetizes the thermomagnetic recording medium on the recording magnetic drum 1 by magnetizing it in a fixed direction. This demagnetization utilizes a characteristic of a certain kind of magnetic medium in which the magnetization decreases when the magnetic moment is magnetized in a certain direction and then the temperature is raised, and the residual magnetization exhibits demagnetization or demagnetization before the temperature rise. Is. (2) Next, the magnetic recording means 3 forms a predetermined magnetic latent image on the thermomagnetic recording medium. This magnetic recording means utilizes the thermal remanent magnetization effect. (3) Next, the developing means 4 attaches toner onto the magnetic latent image, so that the magnetic latent image is visualized. Here, the toner adheres to the portion where the lines of magnetic force due to the leakage magnetic field on the surface of the magnetic recording medium intersect the surface of the magnetic recording medium, and as a result, the magnetic latent image is visualized. (4) After that, the transfer means 5 and the fixing means 6 transfer the visible image onto the paper and fix it. Examples of the transfer means include electrostatic attraction transfer, magnetic attraction transfer, pressure transfer, and thermal demagnetization transfer. (5) Finally, the cleaning unit 7 removes the residual toner on the thermomagnetic recording medium and ends the printing process.

By the way, in the process (2), as a method of forming a magnetic latent image on a thermomagnetic recording medium, there are a heating method using a thermal head and a heating method using laser beam irradiation. There are two types of recording on a thermomagnetic recording medium, in-plane recording and perpendicular recording, depending on the magnetization direction. In-plane recording is recording in a direction parallel to the surface of the thermomagnetic recording medium, and perpendicular recording is recording in a direction perpendicular to the surface of the thermomagnetic recording medium.

[0008] Generally, when high resolution is required, vertical recording which can obtain high density recording is used. As a thermomagnetic recording medium used for this perpendicular recording, an alloy film of a rare earth element and an iron group element, that is, a RE-TM alloy film or a Co-Cr alloy film is used. The RE-TM
The alloy film is suitable for forming a magnetic latent image by irradiating heat, that is, light, and is used for a magneto-optical disk using a thermomagnetic recording method.

On the other hand, the Co--Cr alloy film is suitable for forming a magnetic latent image by applying a signal magnetic field, and is often used for a magnetic disk using a magnetic head recording method. Further, a thin film obtained by heat-treating these multilayer films in the atmosphere to improve the residual magnetic flux density, such as a Co / Pt multilayer film or a Co / Pd multilayer film, can also be used for perpendicular recording. In this case, the multilayer film is magnetized in the perpendicular direction to form a perpendicular magnetization film.

[0010]

However, the above-mentioned conventional thermomagnetic recording media have the following problems, respectively. (1) When a thermomagnetic recording medium is formed of a Co—Cr alloy film, the Curie temperature is high, and thus thermomagnetic recording is difficult. (2) When the thermo-magnetic recording medium is formed of the RE-TM alloy film, the residual magnetic flux density is low, so that the toner adhesion is insufficient. (3) Further, the Co / Pt multilayer film and the Co / Pd multilayer film are
Since the coercive force and the residual magnetic flux density are not sufficiently large, high density thermomagnetic recording is difficult. (4) Therefore, the magnetic printer using the perpendicular magnetization film for perpendicular recording has the advantages that the recording stability is high in principle, high resolution can be obtained, and it operates with low power consumption. There is no thermomagnetic recording medium with sufficient properties necessary to exert its advantages.

The present invention solves the above-mentioned problems of the conventional thermomagnetic recording medium, has a sufficiently high residual magnetic flux density, has a large coercive force and has magnetic characteristics, and is suitable for high density recording for perpendicular recording. An object is to provide a thermomagnetic recording medium.

[0012]

Therefore, in the thermomagnetic recording medium of the present invention, a magnetic film made of an Nd-Fe-B alloy thin film and a non-magnetic substrate on which the magnetic film is formed are formed. Is capable of withstanding the heat treatment for forming the magnetic film. Further, when the composition of the Nd-Fe-B alloy and _{(Nd x Fe 100 -X) 100} -Y B Y, the range of X and Y and Y ≧ 10,10 ≦ X ≦ 25.

On the other hand, the non-magnetic substrate is made of stainless steel foil or copper foil and can withstand a heat treatment of at least 460 ° C.

[0014]

According to the present invention, the use of the Nd-Fe-B alloy thin film as the thermomagnetic recording medium as described above enables high density recording by perpendicular recording and high quality printing. It is possible to provide.

[0015]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 is a sectional structure of the thermomagnetic recording medium of the present invention. In FIG. 1, 10 is a substrate and 20 is a magnetic film. First, the substrate 10 will be described.

The substrate 10 is non-magnetic and is made of a material that can withstand heating when forming a magnetic film on the substrate 10. In the first embodiment of the present invention, a stainless foil having a thickness of 0.1 mm is used. Next, the magnetic film 20 will be described. The magnetic film 20 is formed on the substrate 10, and the magnetic film 20 is formed by sputtering using an RF magnetron sputtering device or the like.

The sputtering conditions are, for example, a sputtering gas pressure of 0.5 Pa, a sputtering power of 300 W, and
The temperature of the substrate 10 at the time of sputtering can be set to 460 ° C. And the composition of the sputtering target,
In the first embodiment of the present invention, Nd ₁₇ Fe ₆₆ B ₁₇ is used.

FIG. 2 is a magnetization loop characteristic diagram of the magnetic film produced under the above conditions. At this time, the thickness of the magnetic film 20 is 500 nm, the coercive force is 3 kOe, and the residual magnetic flux density is 6 kG. It can be confirmed that a high resolution of 100 lines / mm or more is possible as a result of printing by using the thermomagnetic recording medium of the first embodiment of the present invention to form a magnetic latent image and printing by the thermomagnetic recording.

A thermal magnetic head is used to form the magnetic latent image, and black magnetic toner is used as the toner. Next, a second embodiment of the present invention will be described. First, the substrate 10 will be described. In the second embodiment, a 0.1 mm thick copper foil is used as the substrate 10 as a material that can withstand heating when forming a magnetic film.

Next, the magnetic film 20 will be described. Also in the second embodiment of the present invention, as in the first embodiment, the magnetic film 20 is formed on the substrate 10, and the magnetic film 2 is formed.
As a method for producing 0, sputtering is performed using an RF magnetron sputtering device or the like, and the sputtering conditions are, for example, a sputtering gas pressure of 0.5 Pa,
The sputtering power is 300 W, and the temperature of the substrate 10 during sputtering is 460 ° C.

The composition of the sputtering target is Nd ₁₇ Fe ₆₆ B ₁₇ as in the first embodiment. As a result, a magnetic latent image is formed using the thermomagnetic recording medium of the second embodiment of the present invention, and as a result of printing by the thermomagnetic recording, a high resolution of 100 lines / mm or more is possible. I can confirm.

Therefore, as the substrate material of the thermomagnetic recording medium of the present invention, any material that is nonmagnetic and can withstand heating can be used. Next, the third aspect of the present invention
An example will be described. In the third embodiment,
Nd-Fe-B used for magnetic film 20 of thermomagnetic recording medium
The change in the magnetic characteristics with respect to the composition will be described.

In this embodiment, the method of forming the magnetic film 20 is the same as that of the first embodiment, and stainless steel foil is used as the material of the substrate 10 and its film thickness is 300 nm. FIG. 3 is a residual magnetization characteristic diagram for a magnetic film having the composition of the Nd-Fe-B alloy thin film of the present invention. In FIG. 3, the horizontal axis represents the X component ratio of the composition (Nd _X Fe _100-X ) _100-Y B _Y , and the vertical axis represents the residual magnetization. And, the ○ mark is the above (Nd
_In the composition of _X Fe _100-X ) _100-Y B _Y , when Y is 17, the composition (Nd _X Fe _100-X ) ₈₃ B ₁₇ changes depending on the X component ratio. Nd _X Fe _100-X )
In the composition of the _100-Y B _Y, shows a change by X component ratio of the composition _{(Nd X Fe 100-X)} 90 B 10 when the Y and 10.

From FIG. 3, the composition is (Nd _15.5 Fe _84.5 ) ₈₃ B
_The maximum residual magnetic flux density is obtained at ₁₇ points, and the value is 9.5 kG. The residual magnetic flux density is B or Fe.
There is a tendency that the larger the component ratio of, the larger. However, the composition (Nd ₈ Fe ₉₂₎ near _{100-Y B Y, (Nd} 8 Fe
₉₂ ) The residual magnetic flux of ₈₃ B ₁₇ is (Nd ₈ Fe ₉₂ ) ₉₀ B ₁₀
Is larger than the residual magnetic flux of the composition, the in-plane magnetization component increases, and the perpendicular component magnetization decreases.

Therefore, the effective composition range of Nd is 10 to 25 from the magnetization characteristics of FIG. Further, the composition Y of B must be 10 or more. It should be noted that the present invention is not limited to the above-described embodiments, and various modifications can be made based on the spirit of the present invention, and these are not excluded from the scope of the present invention.

[0026]

As described above in detail, according to the present invention, Nd-Fe-B is used as a recording material for a thermomagnetic recording medium.
By using the alloy thin film, a thermomagnetic recording medium having an extremely high residual magnetic flux density can be produced, and a print can be produced with a high resolution of 100 lines / mm or more.

[Brief description of drawings]

FIG. 1 is a cross-sectional structure of a thermomagnetic recording medium of the present invention.

FIG. 2 is a magnetization loop characteristic diagram of the magnetic film of the present invention.

FIG. 3 is a residual magnetization characteristic diagram for a magnetic film having a composition of Nd—Fe—B according to the present invention.

FIG. 4 is a printing process diagram of a conventional thermomagnetic printer.

[Explanation of symbols]

 10 substrate 20 magnetic film

Claims (5)

[Claims] 1. A thermomagnetic recording medium comprising: (a) Nd-
A magnetic film made of an Fe-B alloy thin film; and (b) a non-magnetic substrate on which the magnetic film is formed. (C) the non-magnetic substrate can withstand heat treatment for forming the magnetic film. (D) A thermomagnetic recording medium, wherein the magnetic film is used as a recording layer according to a magnetic latent image. 2. The composition of the Nd-Fe-B alloy is (Nd
_{The thermomagnetic} recording medium according to claim 1, wherein the range of X and Y is Y ≧ 10 10 ≦ X ≦ 25, where _x Fe _100-X ) _{100- Y BY} . 3. The thermomagnetic recording medium according to claim 1, wherein the non-magnetic substrate is a stainless steel foil. 4. The thermomagnetic recording medium according to claim 1, wherein the non-magnetic substrate is a copper foil. 5. The thermomagnetic recording medium according to claim 1, wherein the heat treatment is at least 460 ° C.