JPH06215371A - Apparatus for production and production of magnetic recording medium - Google Patents

Abstract

PURPOSE:To provide the high-quality magnetic recording medium which curls less by providing a roll driving device having a positive relation between the rotating speed and rotating torque of a roll for impressing tension in a transporting direction of a film. CONSTITUTION:The film 2 is sent via rolls 3, 4 to a can 11 and is formed with a magnetic film on one surface. The film is sent via a roll 15 to a roll 13. The film 2 is then sent to a can 12 where the magnetic film is formed on its rear surface. The film is taken up on a roll 8. The constant speed transportation of the film 2 is executed by the pinch roll 13 mounted to a driving motor 10 and, therefore, the tension of the film 2 on the can 11 is controlled by a brake 9 which is mounted to the feeding roll 3 and for which an eddy current brake is used. On the other hand, a differential gear 17 mounted with a driving motor 18 of an induction system and a brake 19 is connected to the shaft of the roll 8. The rotating speed of the motor 18 is kept constant at a speed at which the motor rotates faster by 20% than the speed at which the rotating speed of the take-up roll 8 synchronizes with the transporting speed of the film 2.

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 manufacturing apparatus and method.

[0002]

2. Description of the Related Art Generally, a magnetic recording medium using a continuous magnetic material as a recording medium is manufactured by a sputtering method or a vapor deposition method in a vacuum apparatus. A conventional floppy disk or magnetic tape using a continuous magnetic material as a recording medium has been manufactured using a manufacturing apparatus as shown in FIG. That is, a long film 2 is conveyed from a delivery roll 3 to a guide roll 4 and a can 5 in a vacuum container 1, and a magnetic film is formed on one surface of the film 2 by sputtering of a target 6 on the can 5, and then, It is wound around the winding roll 8 via the guide roll 7. Here, a brake 9 is attached to the delivery roll 3 to apply tension to the film 2. A drive motor 10 using an induction motor is attached to the winding roll 8 to convey and wind the film 2 during formation of the magnetic film. For example, when the recording medium to be manufactured is a single-sided medium such as a floppy disk or a magnetic tape, a metal film or the like is formed on the back side or a double-sided medium in order to prevent curling due to a difference in thermal expansion between the film and the magnetic film. In the case of, in order to form a magnetic film on the back side as well, a magnetic film is formed on one side, and the film wound on the winding roll is set again on the delivery roll side, and the same as the first surface. Then, it is conveyed from the delivery roll 3 to the guide roll 4 and the can 5, and a magnetic film is formed on the second surface of the film 2 on the can 5. The film, which has been formed on both sides and then wound around the winding roll 8 via the guide roll 7, undergoes post-processes such as pressing and slitting to produce a floppy disk and a magnetic tape. Here, the manufactured floppy disk or magnetic tape is required to have a small amount of curl that causes a modulation error during magnetic recording / reproduction, in addition to a predetermined magnetic property. This is especially important for floppy disks for high recording density. This curl amount is generated by the balance of the forces that the film and the magnetic film try to shrink due to the cooling after the magnetic film is formed on the can and the release of the tension. Therefore, when a thin film such as a magnetic film or a metal film is formed on one surface of the film by changing the tension at the time of transporting the film, the tension applied to the film at the time of film formation and the film formation are formed as shown in FIG. 5A. There is a correlation between the subsequent curl amounts, and the curl amount can be controlled by the tension. Next, looking at the curl amount after forming the film on the first one side and the curl amount after forming the film on both sides, as shown in FIG. There is a relationship with the amount of curl after that, and if the amount of curl when the film is formed on the first side is small, the amount of curl after forming both sides can be controlled to be small. As described above, since the tension of the film when forming the magnetic film greatly contributes to the amount of curl, it is important for the stability of the tension, that is, the fluctuation of the tension of the film is small, for controlling the curl amount. It becomes an issue. Regarding the tension of the film during conveyance, in general, a method is used in which a brake is attached to the feed roll to generate a rotational torque that opposes the conveyance of the film to give tension to the film, or an eddy current motor (torque motor) is applied to the drive motor of the winding roll How to attach and to generate a rotating torque to give tension to the film,
The method is roughly classified into a method in which an induction motor is attached to a drive motor of a take-up roll and a tension is generated in the film by providing a speed difference with the transport speed of the film.
Among these, the method of attaching the induction motor to the drive motor of the take-up roll requires a detection mechanism for measuring the film tension, but a film tension detection mechanism with sufficient reliability in vacuum has been put to practical use. Therefore, it is not suitable for a method of manufacturing a magnetic recording medium using vacuum. In addition, comparing the method of attaching the brake with the method of attaching the eddy current motor (torque motor), it is better than the variation with time of the tension of the film when the tension of the eddy current motor is applied to the winding roll shown in FIG. The time-dependent fluctuation of the tension of the film in which tension is applied to the feed roll shown in FIG. 6 (b) by using a brake such as an eddy current brake has a smaller difference between the maximum value and the minimum value, that is, less variation in tension. Therefore, since more stable tension control can be performed, it is more suitable to use a device equipped with a brake in the manufacture of a magnetic recording medium utilizing vacuum.
In the conventional technique described above, in order to form the magnetic films on both sides of the film, it is necessary to perform the steps of forming the one side, resetting the film, and evacuating again, so that the productivity is low.

In order to eliminate the need for film resetting and exhausting time after forming one side and shortening the manufacturing time, as shown in FIG. 7, there are two cans A11 and B12, each of which has a can A11. It has been attempted to provide a pinch roll 13 between the can B12 and the feed roll 3 to control the tension of the can A11 and the take-up roll 8 to control the tension of the can B12 so that both sides are continuously and simultaneously formed. However, there is a problem that the control of the film tension is insufficient and the yield is deteriorated because the tension control of the film on the can for forming the film on the second surface is incompletely controlled. That is, in the method using such a device, the tension of the film on the can A11 is applied by the delivery roll 3 in the same manner as in the conventional case. On the other hand, the tension of the film on the can B12 is applied by the take-up roll 8, so it is necessary to apply the tension from the same direction as the transport direction of the film 2. For this reason, an eddy current motor (torque motor) is attached to the drive motor 14 of the winding roll 8 to apply tension and to wind the film 2. However, in the method in which the eddy current motor is attached and the tension is applied, as described above (see FIG. 6A), since the fluctuation of the tension is large, the control of the tension for setting the curl amount to 0 is sufficient. Therefore, there is a problem that the yield rate is low.

[0004]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to solve the above-mentioned problems and to control the tension on each can within a sufficiently small amount of fluctuation so that both surfaces are kept in the same vacuum container. To provide a magnetic recording medium manufacturing apparatus and a manufacturing method in which a magnetic film and a metal film are formed on both surfaces of a film so that sputtering can be continuously performed and manufacturing time is shortened and quality is improved, that is, productivity is improved. It is in.

[0005]

According to the present invention, one vacuum container is provided with two or more cans, and a sending roll for sending out a long film and a winding roll for accommodating the long film are provided on both sides of the can. A long film is conveyed at a constant speed by a pinch roll provided between the cans, and a magnetic film is formed on the film by sputtering or vapor deposition while the tension of the film on each can is independently controlled. A method of manufacturing a magnetic recording medium, characterized in that a roll driving device having a positive relationship between a rotational speed of a roll for applying a tension in a film transport direction and a rotational torque is at least in a control range. An apparatus for manufacturing a magnetic recording medium, and a method for manufacturing a magnetic recording medium manufactured using the apparatus.

[0006]

The present inventors have found that, in the method of applying tension to the film, the method of applying the tension by attaching the eddy current motor (torque motor) has a smaller fluctuation amount of the tension than the method of applying the tension by attaching the brake. As a result of repeated studies on the cause of the increase, it was found that the cause was the difference in the relationship between the rotation speed of the roll transmitting the tension and the magnitude of the rotation torque. That is, regarding the relationship between the rotation speed of the roll and the rotation torque when the brake is attached, the torque amount increases in proportion to the rotation speed as shown in FIG. 8A, while the eddy current motor is attached. In this case, as shown in FIG. 8B, even if the rotation speed increases, the torque amount tends to decrease. When the tension of the film suddenly becomes small due to some reason, the conveyance speed of the film becomes high. At this time, if the brake is attached, the roll speed increases due to the increase in the film transport speed, and the torque increases due to the relationship between the rotation speed and the amount of torque. Return. On the other hand, if an eddy current motor is attached to apply tension from the film transport direction, the torque amount will be smaller due to the relationship between the rotation speed and the torque amount, even if the rotation speed of the roll increases. Due to this tendency, the changed tension remains unchanged or the amount of fluctuation increases. Therefore, when the tension is applied in the film transport direction, if the rotation speed of the roll on the take-up roll side is increased, the torque amount is also increased.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows the configuration of a manufacturing apparatus used in a method of manufacturing a magnetic recording medium according to an embodiment of the present invention. In the present invention, the film 2 is sent from the delivery roll 3 to the can A11 via the guide roll 4, and a magnetic film is formed on one surface of the film 2. Film A2 with Can A11
The film 2 having the magnetic film formed on the first one surface thereof is sent to the pinch roll 13 via the guide roll 15.
The film 2 that has passed through the pinch roll 13 is conveyed to the can B 12 via the guide roll 16 and the like,
A magnetic film is formed on the second one surface (back surface) of the. Can B
The film 2 having magnetic films formed on both sides up to 12 is wound up by the winding roll 8 via the guide roll 7 and the like. Here, the constant speed conveyance of the film is performed by the pinch roll 13 to which the drive motor 10 using the induction motor is attached. Therefore, can A
The tension of the film on 11 is controlled by a brake 9 using an eddy current brake attached to the delivery roll 3. On the other hand, a differential gear 17 is connected to the shaft of the take-up roll 8, and a drive motor 18 and a brake 19 are attached to the differential gear 17. An induction motor is used as the drive motor 18, and the rotation speed of the drive motor is constant at a speed at which the rotation speed of the winding roll 8 rotates 20% faster than the speed at which the rotation speed of the take-up roll 8 is synchronized with the film transport speed while the brake 19 is locked. did. The brake 19 is an eddy current brake. In this state, the winding roll 8 was rotated to wind the film 2, and the tension thereof was controlled by controlling the amount of torque generated by the brake 19. Therefore,
The winding roll 8 that controls the tension of the film 2 on the second can B12 is driven by a roll driving device that combines an induction motor and an eddy current brake with a differential gear. In this device, the rotation speed of the roll is The torque relationship is set to have a positive relationship.

As an example, Table 1 was obtained by the above-mentioned manufacturing apparatus.
Under the conditions shown in (3), a 3.5-inch floppy disk having Co-Cr alloy magnetic films on both sides was prepared. For comparison, a sample prepared in the same manner as the embodiment under the conditions shown in Table 1 by the conventional can manufacturing apparatus shown in FIG. 4 as Comparative Example 1 and a can having the configuration shown in FIG. 7 as Comparative Example 2. The differential gear 17, the drive motor 18 using an induction motor and the brake 19 using an eddy current brake are removed from the two manufacturing devices, that is, the winding roll 8 of the device of the embodiment, and the eddy current motor is removed. 14
Was attached to the take-up roll 8 to prepare a 3.5-inch floppy disk as a sample produced by using a production apparatus in which the winding of the film from the can B and the tension control were performed only by the eddy current motor. The variation in curl amount was measured for the samples prepared by each of these methods.
The tension conditions were set such that the curl amount was 0 both when forming the one side and when forming the back side. Here, the curl amount was the height of the warp at the outer peripheral end of a 3.5-inch micro floppy disk which was pressed.
At this time, a curl having a height of 0.4 mm or less was regarded as a good product. The specifications of the sample preparation are shown in Table 1 and the results are shown in FIG. As can be seen from FIG. 2, with respect to the variation in curl height, the same result was obtained in Comparative Example 1 and Example. Further, when comparing Comparative Example 2 and the example, the ratio of non-defective products in the example is four times or more. Further, regarding Comparative Example 1 and Example,
The relationship between the production time and the production amount of non-defective products is shown in FIG. As can be seen from FIG. 3, in the example, the waiting time such as the film setting and the exhaust time is about half that of the comparative example 1, and since the non-defective rate is high, the production amount per unit time after that also doubles. The nature is improving.

[0009]

[Table 1]

[0010]

As described above, according to the present invention, it is possible to provide a manufacturing apparatus and a manufacturing method capable of obtaining a high-quality magnetic recording medium with improved productivity and less curl. Although the present invention has been described above with reference to an example in which the magnetic recording medium is manufactured by the sputtering method, the thin film forming method is not limited to the sputtering method, and the same effect can be obtained by the vacuum deposition method or the ion plating method. It's obvious. Further, the application of the invention is not limited to the production of a magnetic recording medium, and it is obvious that the present invention has an effect if it is an apparatus for forming thin films on both sides of a film.
Further, in the embodiment, as the roll driving device in which the relationship between the rotation speed of the roll and the rotation torque is positive, the combination of the induction motor coupled with the differential gear and the eddy current brake has been described, but this relationship is satisfied even with a single motor. If so, the effect of the present invention can be obtained.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a configuration of a magnetic recording medium manufacturing apparatus according to an embodiment of the present invention.

2A and 2B are diagrams showing variations in curl height of manufactured media. FIG. 2A shows an example, FIG. 2B shows a comparative example 1, and FIG. 2C shows a comparative example 2.

FIG. 3 is a diagram showing the relationship between the drive time of the device and the production amount.

FIG. 4 is an explanatory diagram showing a configuration of a manufacturing apparatus used in a conventional manufacturing method.

FIG. 5 is a diagram showing a relationship between a curl amount and a tension when a conventional manufacturing apparatus is used. FIG. 5A is a relationship between the tension and the curl amount when a film is formed on the first surface. b) shows the relationship between the amount of curl after film formation on both surfaces and the amount of curl after formation on the first surface.

FIG. 6 is a diagram comparing a tension applying method with a brake and a motor torque and a variation amount of the tension.
FIG. 6A shows a change in film tension caused by an eddy current motor, and FIG. 6B shows a change in film tension caused by an eddy current brake.

FIG. 7 is an explanatory diagram showing a configuration of a manufacturing apparatus for simultaneous simultaneous production of both surfaces, which is an example of a conventional manufacturing apparatus.

FIG. 8 is a diagram showing a relationship between a rotation speed of a roll and a torque in a method of applying a tension to a film by a brake or a motor. FIG. 8A shows a case where an eddy current brake is used, and FIG. Shows the case where an eddy current motor is used.

[Explanation of symbols]

 1 in a vacuum container 2 film 3 feed roll 4 guide roll 5 can 6 target 7 guide roll 8 take-up roll 9 brake 10 drive motor 11 can A 12 can B 13 pinch roll 14 drive motor 15 guide roll 16 guide roll 17 differential gear 18 Drive motor 19 Brake

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[Procedure amendment]

[Submission date] December 9, 1993

[Procedure Amendment 1]

[Document name to be corrected] Drawing

[Correction target item name] All drawings

[Correction method] Change

[Correction content]

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[Fig. 2]

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Claims (2)

[Claims] 1. A vacuum container is provided with two or more cans, and on both sides thereof a delivery roll for delivering a long film and a winding roll for accommodating the cans, and a pinch roll provided between the cans. In a method for producing a magnetic recording medium, in which a long film is conveyed at a constant speed and the tension of the film on each can is independently controlled, a magnetic film is formed on the film by sputtering or vapor deposition, An apparatus for manufacturing a magnetic recording medium, comprising a roll driving device having a positive relationship between a rotational speed and a rotational torque of a roll for applying a tension in a film transport direction, at least within a control range. 2. A method for manufacturing a magnetic recording medium, which is manufactured by using the apparatus according to claim 1.