JP4906149B2 - Method and apparatus for manufacturing magnetic recording medium - Google Patents

Description

【００３５】
表１から明らかなように、電子ビーム収束幅は比較例１〜３が６０ｍｍであるのに対し、実施例１〜３では１０ｍｍ未満と観測状態が改善されていることが分かる。同様に走査状態も、比較例１〜３のものは全く目視では見えない状態であったが、実施例１〜３ではほぼ静止状態で観測することができた。また、電磁変換特性の変動は比較例１〜３では±１．２〜１．５ｄＢまで大きく変動しているのに対して、実施例１〜３では電子ビームの位置制御を確実に行うことができた結果、±０．３％と変動幅が大幅に改善された。同様に、エラーレートは比較例１〜３が８〜９×１０^−５であったのに対し、実施例１〜３では１〜２×１０^−５と改善された。さらに、膜厚変動率も比較例１〜３が±１７〜１８％の変動があったのに対し、実施例１〜３では±４〜５％と改善された。
【００３６】
【発明の効果】
以上説明してきたように、本発明によれば、電子ビームの投入パワーが増大した状況下においても作業能率が格段に向上し、かつ異常照射が防止される。その結果、効率よくかつ安全に、品質の安定した蒸着膜を得ることができる。
【図面の簡単な説明】
【図１】磁気記録媒体の製造装置を説明するための模式図である。
【図２】（イ）は、可変速式遮光用回転シャッター装置の外観を示す斜視図である。
（ロ）は、上記可変速式遮光用回転シャッター装置の内部構造を示す断面図である。
【図３】本発明の好適例の可変速式遮光用回転シャッター装置の部分側面図である。
【図４】電子ビーム投入パワーによるビーム収束状態の差異を示す説明図である。
【図５】るつぼ上を電子ビームが走査する状態を示す説明図である。
【符号の説明】
１，１０１ 斜め蒸着装置
２ 非磁性基体
３ 供給ロール
４ 冷却ドラム
５ 蒸着るつぼ
６ 電子銃
６Ｂ 電子ビーム
７ 巻き取りロール
８ 真空排気ポンプ
９ 遮蔽板
１０ シャッター
１１ 遮光用シャッター装置
１２，１１２ 外縁部
２１，１２１ 可変速式遮光用回転シャッター装置
２２，１２２ 真空取付けフランジ
２３ スリット
２４，１２４ 覗き窓
２５，１２５ 回転モーター
２６，１２６ 回転軸
２７，１２７ 円筒体
２８，１２８ 円筒形ジャケット
２９，１２９ 円盤
３０，１３３ 変圧器
３１ 電子銃
３１Ｂ 電子ビーム
３２ 電子ビーム偏向コイル
３３ 蒸着るつぼ
３４ 照射位置
１３０ 回転軸
１３１ プーリー
１３２ ベルト
Ｗ 電子ビーム収束幅[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method and an apparatus for manufacturing a magnetic recording medium, and more particularly, in a vacuum vessel equipped with an electron gun and a vapor deposition crucible, vapor deposition material in the vapor deposition crucible is evaporated by an electron beam emitted from the electron gun. In addition, the present invention relates to a method and an apparatus for manufacturing a magnetic recording medium capable of accurately monitoring such an electron beam when depositing it on a material to be deposited.
[0002]
[Prior art]
Vapor deposition is a technique in which a vapor deposition material in a vapor deposition crucible is evaporated by an electron beam generated by an electron gun in a vacuum vessel and vapor deposited on the material to be deposited.
[0003]
One application example of such a vapor deposition technique is the formation of a ferromagnetic metal thin film of a magnetic recording medium. In this film forming process, a magnetic tape having a magnetic layer of a ferromagnetic metal thin film mainly composed of Co (cobalt) or Co and further containing Ni (nickel), Cr (chromium) or the like is formed by an oblique deposition method. It is known that a magnetic tape having a ferromagnetic metal thin film formed as described above as a magnetic layer has a high saturation magnetic flux density and a high coercive force, and exhibits excellent electromagnetic characteristics.
[0004]
In such an oblique vapor deposition method, a ferromagnetic metal vapor is made incident on the surface of a nonmagnetic substrate at a specific angle to form a ferromagnetic metal thin film composed of columnar crystal particles inclined with respect to the substrate. In the conventional oblique deposition method, for example, an oblique deposition apparatus 1 having a configuration schematically shown in FIG. 1 is used. In this oblique vapor deposition apparatus 1, a long film-like nonmagnetic substrate 2 is unwound from a supply roll 3 in a vacuum container and conveyed along the surface of a rotating cooling drum 4, while being placed in a stationary vapor deposition crucible 5. By irradiating the electron beam 6B from the electron gun 6 to the ferromagnetic metal, which is the vapor deposition material, to form a molten metal of the vapor deposition material, and to generate an evaporation material of the vapor deposition material and perform oblique vapor deposition, A ferromagnetic metal thin film is formed on the surface. Confirmation of the irradiation position of the electron beam into the vapor deposition crucible 5 has been performed with an electron beam monitoring viewing window provided with a light shielding shutter device 11 provided on the side surface of the vacuum vessel.
[0005]
The nonmagnetic substrate 2 on which the ferromagnetic metal thin film is formed is wound up on a winding roll 7. The shielding plate 9 is provided to regulate the incident angle of the deposited ferromagnetic metal. An opening is formed in the shielding plate 9 so that the evaporated metal is deposited only at a predetermined portion of the nonmagnetic substrate 2, and a shutter 10 is provided in the opening, and arrows are provided at the initial stage and the end stage of the deposition. It has the function of blocking the opening and preventing unnecessary vapor deposition. Further, an oxygen supply nozzle (not shown) is provided between the shielding plate 9 and the shutter 10 in order to introduce a gas such as oxygen into the vapor deposition section. Furthermore, an evacuation pump 8 is provided to keep the inside of the vacuum vessel at a predetermined pressure.
[0006]
In such a vapor deposition apparatus 1, when the input power of an electron beam for Co vapor deposition increases with today's mass production, the focal point of the electron beam 6 </ b> B diffuses due to repulsion between electrons, and the electrons in the vapor deposition crucible 5. A state occurs in which the beam irradiation position cannot be confirmed.
[0007]
Conventionally, as shown in FIG. 4 (a), since the injection power of the electron beam 31B emitted from the electron gun 31 was small, the focus was focused on the irradiation position 34 into the evaporation crucible 33. The confirmation is simple, and the light blocking shutter device 11 shown in FIG. 1 only has to be able to block a large amount of light from the evaporation source to a light amount that allows visual confirmation. However, as the input power of the electron beam increases, the focus of the electron beam 31B emitted from the electron gun 31 is diffused as shown in FIG. 4B, making it difficult to confirm the irradiation position. Specifically, when the input power is increased from the state where the electron beam irradiation position is in focus, the focus gradually diffuses and the entire deposition crucible emits white light, and even if there is a light shielding shutter device, the irradiation position I can no longer confirm.
[0008]
If the electron beam irradiation position does not accurately come to the center of the deposition crucible, the quality will be adversely affected, such as deterioration of electromagnetic conversion characteristics due to deviation of the incident angle, dropout and error rate increase due to bumping, and unstable magnetic layer thickness. There is a danger of giving. Further, when the irradiation was continued without confirming the electron beam irradiation position, the electron beam 6B was directly irradiated to the vapor deposition crucible 5 or the main body of the apparatus 1, and there was a risk of damaging them.
[0009]
In order to avoid such a risk, the vapor deposition apparatus disclosed in Japanese Patent Application Laid-Open No. 6-81135 is provided with an electron beam abnormal irradiation detection device, and the electron beam is irradiated to members and portions other than the vapor deposition material in the vapor deposition crucible. By detecting abnormal X-rays generated by this, and stopping the operation of the electron gun based on the detection result, damage to the vapor deposition crucible and the apparatus main body is prevented.
[0010]
[Problems to be solved by the invention]
According to the technique described in Japanese Patent Laid-Open No. Hei 6-81135, when it is detected that the electron beam has come off the vapor deposition crucible, the entire apparatus is stopped. Although it can be avoided, the apparatus must be stopped one by one, so that there is a problem that work efficiency is extremely deteriorated. Such a problem is particularly remarkable when the vapor deposition material is a ferromagnetic material.
[0011]
In addition, it is necessary to monitor the melted surface in the vapor deposition crucible at the time of vapor deposition. However, since the light emission associated with melting by the electron beam has a very high luminance, it is impossible to monitor with the naked eye as it is. For this reason, as described above, there has been proposed a method of providing a light-shielding rotary shutter mechanism in the observation window for confirming the electron beam irradiation position (for example, Japanese Patent Laid-Open No. 3-030257). When the input power is increased, it is inevitable that even if a rotating shutter mechanism for shielding light is provided, it becomes difficult to confirm the beam position due to the diffusion of the beam due to electron repulsion.
[0012]
Therefore, an object of the present invention is to solve the above-mentioned problems, and even if the input power of the electron beam is increased, the irradiation position of the electron beam can be reliably confirmed from the outside, and the vapor deposition operation is performed efficiently. It is another object of the present invention to provide a method and an apparatus for manufacturing a magnetic recording medium that can obtain a deposited film with stable quality.
[0013]
[Means for Solving the Problems]
As a result of intensive studies to solve the above problems, the present inventors have found that the object can be achieved by monitoring the electron beam while shielding light in a period synchronized with the scanning frequency of the electron beam or in the vicinity thereof. The headline and the present invention were completed.
[0014]
That is, the method for manufacturing a magnetic recording medium of the present invention evaporates the vapor deposition material in the vapor deposition crucible by an electron beam emitted from the electron gun in a vacuum vessel equipped with an electron gun and a vapor deposition crucible. In the method of manufacturing a magnetic recording medium in which the material is vapor-deposited on the material to be vapor-deposited, the electron beam is monitored while being shielded from light in a period synchronized with the scanning frequency of the electron beam or in the vicinity thereof.
[0015]
In the manufacturing method of the present invention, the light shielding period of the observation window is varied while synchronizing with the scanning frequency of the electron beam while visually monitoring the observation beam from the observation window for monitoring the electron beam provided on the side surface of the vacuum vessel. By setting the light shielding period to be performed or the period in the vicinity thereof, the deflection control of the electron beam can be performed satisfactorily.
[0016]
An apparatus for manufacturing a magnetic recording medium according to the present invention includes an electron gun and a vapor deposition crucible in a vacuum vessel, and vaporizes a vapor deposition material in the vapor deposition crucible by an electron beam emitted from the electron gun, which is vapor deposited material In the apparatus for manufacturing a magnetic recording medium to be vapor-deposited, a viewing window hole for electron beam monitoring is formed on the side surface of the vacuum vessel, and a period synchronized with the scanning frequency of the electron beam is provided in the viewing window hole or A variable-speed light-shielding rotary shutter device that shields light in the vicinity thereof is attached.
[0017]
In the manufacturing apparatus of the present invention, the variable-speed light-shielding rotary shutter device includes a disk having slits radially spaced at equal intervals, and a viewing window for monitoring the electron beam at a rotation passing position of the slit. It is preferable. Particularly preferably, the disk is rotated via a rotational drive transmission means disposed between the disk and a motor disposed at a location separated from the disk.
[0018]
By monitoring the electron beam while shielding light at a period synchronized with the electron beam scanning frequency, it is possible to observe the electron beam irradiation position having a period of several hundreds of hertz, which cannot be observed by visual observation, at a single point. . Further, the focus becomes clear even with an electron beam for vapor deposition whose input power has increased with the mass production of today, and the electron beam irradiation position in the vapor deposition crucible can be confirmed well. As a result, it is possible to control the position of the electron beam while reliably observing it with the deflection control of the electron beam. Further, by slightly shifting the synchronization, it is also possible to observe the situation where the observation state of the irradiation position of the electron beam is kept clear and the state being scanned in the crucible. As a result, in the present invention, the work efficiency is remarkably improved, and the electron beam does not irradiate the vapor deposition material and irradiates the vapor deposition crucible and the inner wall of the apparatus main body to damage them (abnormal irradiation). Is prevented. Furthermore, risk factors that adversely affect quality, such as deterioration of electromagnetic conversion characteristics, increase in dropout and error rate, and instability of the magnetic layer thickness, are also eliminated.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, one embodiment of the present invention will be specifically described.
The method for manufacturing a magnetic recording medium of the present invention can be carried out by attaching a variable shutter speed type shutter device to a hole for an electron beam monitoring viewing window of a conventionally used magnetic recording medium manufacturing apparatus. it can. For example, a shutter device capable of changing the light shielding period is installed in a hole for an electron beam monitoring viewing window provided on the side surface of the vacuum vessel, and the light shielding period of the electron beam monitoring viewing window in this shutter device is the electron beam scanning frequency. If the electron beam is monitored by adjusting the shutter so that it becomes a period synchronized with the electron beam, it becomes possible to observe the electron beam irradiation position at a single point, and even if it is a high power electron beam, the irradiation position can be confirmed well It becomes possible to do.
[0020]
In the present invention, the light shielding period of the shutter device includes a neighboring period slightly shifted from the period synchronized with the scanning frequency of the electron beam, and the observation state of the irradiation position is clear even in the neighboring period. It is possible to observe the situation where the electron beam is scanned as it is. In addition, monitoring of the electron beam is not limited to monitoring through a viewing window, but may be performed by a monitor installed in a vacuum vessel, and a shutter device with a variable light-shielding cycle type is attached to the front surface of the lens of the monitor. Can also be done.
[0021]
In the manufacturing method of the present invention, even if a high-power electron beam is used, the irradiation position can be confirmed satisfactorily. This makes it possible to improve work efficiency and prevent abnormal irradiation. The manufacturing method of the present invention provides a manufacturing apparatus for a magnetic recording medium, in particular, a shutter device for light shielding, as long as the viewing window for monitoring an electron beam can be shielded in a period synchronized with the scanning frequency of the electron beam or in the vicinity thereof. Although it may have any structure, a preferred example of the manufacturing apparatus according to the present invention will be specifically described below.
[0022]
In a preferred embodiment of the magnetic recording medium manufacturing apparatus of the present invention, a light-shielding shutter device 11 is attached to an electron beam monitoring viewing window hole provided on the side surface of the vacuum vessel as shown in FIG. The shutter device 11 is a variable-speed light-shielding rotary shutter device with variable light-shielding cycle.
[0023]
A specific example of such a variable-speed light shielding rotary shutter device is shown in FIG. FIG. 2 (a) shows the variable-speed light-shielding rotary shutter device 21 for light shielding when it is not attached to the electron beam monitoring viewing hole, and (b) is an AA shown in FIG. A cut surface along the line is shown. At the time of attachment, the attachment flange 22 at the end of the cylindrical body 27 is joined to the outer edge portion 12 of the hole for the observation window for electron beam monitoring in an airtight state using fastening means such as screws. The end of the cylindrical body 27 opposite to the flange 22 is joined to a cylindrical jacket 28 in which a disk 29 having slits 23 radially arranged at equal intervals is accommodated in an airtight state at a position where the slit 23 passes through, The observation window 24 attached in an airtight state to the opposite side of the cylindrical jacket 28 coincides with its central axis. The cylindrical jacket 28 has holes having the same central axis as that of the central axis on both sides, so that the electron beam in the vacuum chamber can be monitored from the observation window 24 through the slit 23.
[0024]
A disk 29 in the cylindrical jacket 28 is attached to a rotary shaft 26 of a rotary motor 25 having a variable rotation speed connected to a transformer 30, and the observation window 24 is rotated at a desired cycle by rotating the disk 29. It will be shielded from light. At this time, instead of directly attaching the disk 29 to the rotating shaft 26 of the rotary motor 25, a method using a pulley, a rotation transmission means using a rack and pinion, a gear, or the like may be used. Is not particularly limited, but preferably a pulley utilization method is adopted.
[0025]
FIG. 3 shows a specific example of a variable-speed light shielding rotary shutter device using a pulley. FIG. 3 is a side view of the variable-speed light-shielding rotary shutter 121 attached to the electron beam monitoring viewing window hole. The basic structure is the same as that of the type shown in FIG. 2, and when mounting to the oblique deposition apparatus 101, the mounting flange 122 at the end of the cylindrical body 127 is airtight to the outer edge 112 of the hole for the observation window for electron beam monitoring. Joined in state. Here, the disk 129 in the cylindrical jacket 128 has a pulley 131 attached to the rotating shaft 130 outside the cylindrical jacket 128, and a rotary motor 125 having a variable rotational speed connected to the pulley 131 and the transformer 133. The rotary shaft 126 is rotationally driven via a belt 132 disposed between the rotary shaft 126 and the rotary shaft 126. By adopting such a pulley utilization method, the cylindrical body 127 can be shortened, and as a result, an advantage that the internal field of view from the viewing window 124 is widened accordingly.
[0026]
The conventional light-shielding rotary shutter device does not allow the rotational speed to be changed, and can simply achieve the intended purpose if a predetermined rotational speed is obtained. On the other hand, in the present invention, it is important that the rotational speeds of the disks 29 and 129 can be changed. That is, it is important that the rotational speeds of the disks 29 and 129 can be changed so as to be synchronized with the scanning frequency of the electron beam. The means for controlling the rotational speed of the rotary motors 25 and 125 may be any means such as the use of a transformer, but is preferably a means that can be directly operated by a viewing window monitor while monitoring the electron beam.
[0027]
A rotating shutter for light shielding, which is the above variable speed method, is attached to a manufacturing apparatus for oblique vapor deposition that has been used conventionally, and after the light shielding period of the sight glass window is synchronized with the scanning frequency of the electron beam, the deflection of the electron beam is performed. If control is performed, the electron beam can always be deflected to a normal state and irradiated to the correct position in the vapor deposition crucible.
[0028]
The magnetic recording medium manufactured according to the present invention has a magnetic layer including a ferromagnetic metal thin film formed on the nonmagnetic substrate 2 by an oblique vapor deposition method. In the oblique vapor deposition method, it is preferable that after evacuating the inside of the vacuum vessel in which the nonmagnetic substrate 2 can travel to 10 ⁻³ Pa, the evaporation material is heated and melted by the electron gun 6 to be evaporated. As the evaporation material, Fe, Co, Ni magnetic metals alone or a mixed material thereof, or a ternary system such as Co—Ni—Cr, Fe—Ni—N, Co—Ni—Ta may be used. The material itself is not particularly limited.
[0029]
During vapor deposition, an oxidizing gas may be introduced for surface protection and magnetic property control. The oxidizing gas to be introduced can be appropriately selected from oxygen, ozone, nitrous oxide, and the like. The present invention can also be applied to a single magnetic layer or a multilayer film having two or more layers. The total thickness of the magnetic layer is preferably controlled within a range of 30 to 500 nm. If the thickness is less than 30 nm, the still durability becomes unstable. On the other hand, if the thickness is more than 500 nm, the electromagnetic conversion characteristics deteriorate due to increased loss. Further, in the present invention, when the oblique vapor deposition is performed, the rotation direction of the cooling drum may be the same direction or the reverse direction, and it may be designed to satisfy the required electromagnetic conversion characteristics, and is not particularly limited.
[0030]
【Example】
Hereinafter, the present invention will be specifically described based on examples.
A ferromagnetic metal thin film having a magnetic layer thickness of 200 nm is formed on a nonmagnetic substrate 2 made of a polyethylene terephthalate (PET) film having a thickness of 6 μm while introducing oxygen using the oblique vapor deposition apparatus 1 having the structure shown in FIG. did.
[0031]
The average minimum incident angle θmin of the electron beam 6B emitted from the electron gun is 50 degrees, the average distance between the molten metal surface of the Co metal deposition crucible 5 and the deposition surface of the cooling drum 4 is about 300 mm, and the opening width of the shielding plate 9 (magnetic The layer forming width was 500 mm.
[0032]
First, the pressure in the vacuum vessel was kept at 10-3 Pa. In this state, the deflection direction of the electron gun 6 was adjusted so that the electron beam from the electron gun was irradiated on the center of the Co metal of the crucible 5. In this state, the input power of the electron gun is increased, then the non-magnetic substrate 2 is run at 50 m / min, and the Co metal is melted by the electron beam from the electron gun 6 while supplying the Co metal to the crucible 5. And vapor deposition was performed. The electron beam 6B from the electron gun 6 was scanned in the crucible longitudinal direction of the Co metal surface of the crucible 5 as shown in FIG. The power of the electron gun 6 was 200 kW, and the irradiation state was observed at that time. From the gas supply nozzle, an oxygen-based gas was appropriately adjusted and supplied during vapor deposition. The target deposition thickness was 200 nm. The vapor deposition crucible 5 was made of magnesium oxide.
[0033]
The electron beam scanning frequency was 200 hertz. Four types of light-shielding rotary slits shown in FIG. 2 were used. The light shielding period was controlled by controlling the number of revolutions of the slit to confirm the presence or absence of synchronization with the electron beam scanning. The determination was performed by visually observing the electron beam convergence width W (FIG. 5) by visual observation from a viewing window. In addition, the ease of confirming the scanning state is expressed by ◎ ○ × etc. The symbol ◎ indicates that the electron beam scanning state is still or the scanning frequency can be reliably recognized by the eye, the symbol ○ indicates flickering but the scanning is visible, the symbol X indicates that it is hardly visible, and the symbol XX indicates that it is not visible at all. The obtained determination results and the quality evaluation results of the manufactured magnetic tape are shown in Table 1 below.
[0034]
[Table 1]

[0035]
As can be seen from Table 1, the electron beam convergence width is 60 mm in Comparative Examples 1 to 3, whereas in Examples 1 to 3, the observation state is improved to be less than 10 mm. Similarly, the scanning states of Comparative Examples 1 to 3 were not visible at all, but Examples 1 to 3 could be observed in a substantially stationary state. In addition, the electromagnetic conversion characteristics fluctuate greatly from ± 1.2 to 1.5 dB in Comparative Examples 1 to 3, whereas in Examples 1 to 3, the position control of the electron beam can be reliably performed. As a result, the fluctuation range was significantly improved to ± 0.3%. Similarly, the error rate of Comparative Examples 1 to 3 was 8 to 9 × 10 ⁻⁵ , while that of Examples 1 to 3 was improved to 1 to 2 × 10 ⁻⁵ . Furthermore, the film thickness variation rate was improved to ± 4 to 5% in Examples 1 to 3, while the variation in Comparative Examples 1 to 3 was ± 17 to 18%.
[0036]
【Effect of the invention】
As described above, according to the present invention, the work efficiency is remarkably improved and abnormal irradiation is prevented even under a situation where the input power of the electron beam is increased. As a result, it is possible to obtain a vapor deposition film having a stable quality efficiently and safely.
[Brief description of the drawings]
FIG. 1 is a schematic diagram for explaining an apparatus for manufacturing a magnetic recording medium.
FIG. 2A is a perspective view showing an appearance of a variable-speed light-shielding rotary shutter device.
(B) is a cross-sectional view showing the internal structure of the variable-speed light shielding rotary shutter device.
FIG. 3 is a partial side view of a variable-speed light-shielding rotary shutter device according to a preferred embodiment of the present invention.
FIG. 4 is an explanatory diagram showing a difference in beam convergence state depending on electron beam input power.
FIG. 5 is an explanatory view showing a state in which an electron beam scans on a crucible.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1,101 Inclined vapor deposition apparatus 2 Nonmagnetic base | substrate 3 Supply roll 4 Cooling drum 5 Vapor deposition crucible 6 Electron gun 6B Electron beam 7 Winding roll 8 Vacuum exhaust pump 9 Shielding plate 10 Shutter 11 Light shielding shutter apparatus 12, 112 Outer edge part 21, 121 Rotating shutter device 22 for variable speed type light shielding 22, 122 Vacuum mounting flange 23 Slit 24, 124 Viewing window 25, 125 Rotating motor 26, 126 Rotating shaft 27, 127 Cylindrical body 28, 128 Cylindrical jacket 29, 129 Disc 30, 133 Transformer 31 Electron gun 31B Electron beam 32 Electron beam deflection coil 33 Deposition crucible 34 Irradiation position 130 Rotating shaft 131 Pulley 132 Belt W Electron beam convergence width

Claims (5)

At the electron gun and the vapor deposition vacuum container and a crucible, the electron beams emitted from the electron gun to evaporate the deposition material in the vapor deposition crucible, the production of magnetic recording media to be deposited on the deposited material which A method of manufacturing a magnetic recording medium, characterized in that the electron beam is monitored while being shielded from light in a period synchronized with the scanning frequency of the electron beam or in the vicinity thereof.   While performing the monitoring visually from the observation window for electron beam monitoring provided on the side surface of the vacuum vessel, the light shielding period synchronized with the scanning frequency of the electron beam is varied by changing the light shielding period of the observation window. The manufacturing method of Claim 1 to set. And an electron gun and a vapor deposition crucible in a vacuum container, the electron beams emitted from the electron gun to evaporate the deposition material in the vapor deposition crucible, the apparatus for manufacturing a magnetic recording medium to be deposited on the deposited material which A variable-speed type in which a hole for a viewing window for monitoring an electron beam is formed in a side surface of the vacuum vessel, and the hole for the viewing window is shielded in a period synchronized with the scanning frequency of the electron beam or a period in the vicinity thereof. An apparatus for manufacturing a magnetic recording medium, comprising a rotating shutter device for shielding light.   4. The magnetic recording medium according to claim 3, wherein the variable-speed light-shielding rotary shutter device includes a disk having slits radially formed at equal intervals, and a viewing window for monitoring the electron beam at a rotational passage position of the slit. Manufacturing equipment.   5. The apparatus for manufacturing a magnetic recording medium according to claim 4, wherein the disk is rotated via a rotational drive transmission means disposed between the disk and a motor disposed at a location separated from the disk.

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