JPH06338101A - Magnetic-tape driving device and manufacture of capstan shaft thereof - Google Patents

Abstract

PURPOSE:To further increase the tape driving force of a capstan shaft coated with a diamond-like thin-film. CONSTITUTION:A plurality of capstan-shaft element assemblies 1a are irradiated with charged particles while being rolled, fine arc discharge is generated on the surfaces of the capstan-shaft element assemblies 1a, and fine irregularities 1b having height from 10nm to 100nm and pitches from 500nm to 2mum are formed on the surfaces of the capstan-shaft element assemblies 1a. A diamond- like thin-film 1c is formed onto the irregularities 1b to manufacture a capstan shaft 1. Accordingly, a magnetic-tape driving device having driving force higher than conventional capstan shafts coated with the diamond-like thin-film is acquired.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic tape drive used in a magnetic recording / reproducing apparatus such as a video movie or cassette deck, and a method of manufacturing a capstan shaft thereof.

[0002]

2. Description of the Related Art A magnetic recording / reproducing apparatus for a video movie or the like is being researched and developed year by year so as to be compact, lightweight and highly functional. For this reason, studies have been made to coat various thin films in a precision mechanical component of a mechanism typified by a capstan shaft of a magnetic tape drive to realize a more precise mechanism.

One example is Japanese Patent Application No. 3-20916, which is pending.
No. 1 and its configuration will be described with reference to FIG.

In FIG. 14, the capstan shaft 11 is made of non-magnetic stainless steel, and a diamond-like thin film 14 having a Vickers hardness of 1500 kg / mm ² or more is formed on the surface of the capstan shaft 11. It is formed thick.

A magnetic tape 13 (hereinafter referred to as a tape) is pinched by a capstan shaft 11 and a pinch roller 12 pressed against the capstan shaft 11, and driven in a direction indicated by an arrow R by a low speed rotation of the capstan shaft 11. It
In this drive, if the pressure contact force of the pinch roller 12 is small, tape slip may occur and the tape may not be driven sufficiently. Therefore, conventionally, it has been necessary to apply a pressure contact force of 1 kg or more to the pinch roller 12 to press the tape 13 so that the tape 13 does not slip.

On the other hand, coating the capstan shaft 11 with the diamond-like thin film 14 has the advantage that the contact pressure of the pinch roller 12 can be reduced to about half.

By the way, usually, the diamond-like thin film 14
Is said to have a low coefficient of friction, but magnetic tape 13
When the relative speed with respect to is extremely low, the coefficient of friction of the diamond-like thin film 14 shows a higher value than that of ordinary metal. Then, in the tape drive, the relative speed between the capstan shaft 11 and the tape 13 is about 0.1 m.
It is m / sec or less, and is a low speed that is not different from static friction. Therefore, by coating the capstan shaft 11 with the diamond-like thin film 14, the friction coefficient of the capstan shaft 11 with respect to the tape 13 can be increased.

Further, according to the principle of tape driving by the capstan shaft 11, it is considered that the rotational force of the capstan shaft 11 is first transmitted to the pinch roller 12 side, and the pinch roller 12 drives the tape 13. However, in FIG.
As shown in (b), the capstan shaft 11 and the tape 1
When the contact length A with 3 is relatively larger than the contact length B with the capstan shaft 11 and the pinch roller 12,
The friction coefficient between the capstan shaft 11 and the tape 13 has a great influence on the tape drive. Therefore, the capstan shaft 11 coated with the diamond-like thin film 14 can obtain a high tape driving force as much as the friction coefficient between the capstan shaft 11 and the tape 13 is increased.

As a result, even if the pressure contact force of the pinch roller 12 is reduced, it is possible to obtain the same tape drive performance as the conventional one.

[0010]

By the way, in the friction phenomenon of a substance, it is well known that the roughness of the surface of the substance affects the friction coefficient, and generally, it is said that when the roughness is increased, the friction coefficient also increases. It is said that. Regarding the friction between the capstan shaft 11 and the magnetic tape 13, it has been conventionally accepted that if the roughness of the surface of the capstan shaft 11 is increased, the friction coefficient is increased, and it is said that the driving force is also improved. Was there. However, if the surface roughness of the capstan shaft 11 is large, the convex portion of the surface roughness bites into the pressure-bonded tape 13, and this wedge-like effect becomes resistance to the running of the tape 13 and the friction coefficient increases. The capstan shaft 11 and the tape 1
In the case of friction No. 3, when the surface roughness of the capstan shaft 11 becomes larger than a certain range, the driving force tends to decrease. That is, when the surface roughness is too large, that is, when the density of the surface roughness is sparse, the tape 13 and the capstan shaft 11 are rather increased rather than the wedge-like effect of the convex portion.
However, there was a problem that the contact area was reduced and the friction coefficient was reduced.

On the contrary, if the surface roughness of the capstan shaft 11 is small, that is, if the density of the surface roughness is high, the influence of the surface roughness on the coefficient of friction of the capstan shaft 11 with the tape 13 is extremely small. Therefore, it is determined by the inherent friction coefficient value of the material. That is, there is a problem that the tape driving force is determined by the friction coefficient originally possessed by the diamond-like thin film 14 and the friction coefficient becomes small.

In order to solve such a problem, the present inventors have made a capstan shaft 1 coated with a diamond-like thin film 14.
As a result of further examination of the relationship between the surface roughness of No. 1 and the tape driving force, the fact that the tape driving force can be improved over the conventional capstan shaft coated with the diamond-like thin film 14 at the roughness shown below. Was found.

The present invention provides a magnetic tape driving device and a method for manufacturing the capstan shaft, which can further improve the tape driving force of the capstan shaft coated with the diamond-like thin film, based on the above-mentioned examination results. It is an object.

[0014]

SUMMARY OF THE INVENTION The present invention solves the above problems and includes a capstan shaft for driving a magnetic tape,
A pinch roller that press-contacts the magnetic tape to the capstan shaft, the capstan shaft forming a fine uneven surface having a height of 10 nm to 100 nm and a pitch of 500 nm to 2 μm on the surface of the capstan shaft body. Then, a diamond-like thin film is formed on the uneven surface.

The capstan shaft element is irradiated with charged particles while rolling the capstan shaft element so as to be in contact with each other, and fine irregularities are formed on the surface of the capstan shaft element by the irradiation. It is designed to be formed.

[0016]

In the above structure, by forming a fine uneven surface having a height of 10 nm or more and 100 nm or less and a pitch of 500 nm or more and 2 μm or less on the surface of the capstan shaft, the unique coefficient of friction of the diamond-like thin film is A wedge-like effect is added to the tape due to surface irregularities, and the synergistic effect of the two improves the tape driving force.

Further, in the above-mentioned manufacturing method, by rolling the plurality of capstan shafts, the capstan shafts move in position in an unstable contact state with each other. In this state, when charged particles are irradiated and a current is applied to the capstan shaft,
The electric current freely flows between a plurality of capstan shafts in an unstable contact state to cause an instantaneous arc discharge between the capstan shafts, leaving discharge marks on the surface of the capstan shafts. This discharge mark has a maximum height of 10 nm or more and 100 nm or less and a pitch of 50 nm.
Fine irregularities having a size of 0 nm or more and 2 μm or less are formed, and further, as the capstan shaft continues to roll, countless fine irregularities are uniformly formed on the surface of the capstan shaft.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS.

(Embodiment 1) FIG. 1A shows a first embodiment of the present invention.
2B is a configuration diagram of an apparatus for forming minute irregularities on the surface of the capstan shaft element body used in the embodiment of FIG. 1, and FIG. 7B is a configuration diagram of a holding frame that holds the capstan shaft element body.

In the figure, an ion source 22 is installed in a vacuum chamber 21, and a holding frame 23 for holding a plurality of unprocessed capstan shaft element bodies (hereinafter referred to as element bodies) 1a is provided above the ion source 22. There is. The holding frame 23 is provided with a window 24 so that the ions 22a from the ion source 22 directly collide with the element body 1a. Also, the holding frame 2
The eccentric cam 26 interlocked with the motor 25 gives vibration to the element 3 so that the element body 1a to be held is randomly rolled. Further, a DC power supply 27 is connected to the holding frame 23, and a bias voltage is applied to the element body 1a.

In the above apparatus, first, the inside of the vacuum chamber 21 is set to 10 ⁻⁴ to 10 ⁻⁴ by a vacuum pump (not shown).
^The gas is evacuated to ^-6 torr, the hot filament of the ion source 22 is electrically heated, and an inert gas, argon, is introduced to generate argon ions. Next, the holding frame 23 is vibrated by the motor 25, and the element body 1 a is randomly rolled by the holding frame 23. And DC power supply 2
A negative bias voltage of -1.0 to -3.0 kV is applied to the element body 1a from 7 to accelerate the argon ions 22a to collide with the surface of the element body 1a. At this time, the charges of the argon ions 22a that have reached the element body 1a are rolling elements 1a.
After moving through the space, it finally flows into the DC power supply 27.

By such a treatment, innumerable fine irregularities 1b (see FIG. 4) are uniformly formed on the surface of the element body 1a by the minute arc discharge which occurs along with the movement of charges.

FIG. 2 shows measured data of the surface roughness of the element body 1a which has been subjected to the surface roughening treatment in this embodiment.

(A) shows the surface roughness of the element body 1a before the treatment, and (b) shows the surface roughness of the element body 1a after the treatment, which is the same as in the first embodiment of the present invention. According to this, it is understood that innumerable minute irregularities 1b are formed on the surface of the element body 1a.
The size of the unevenness 1b has a maximum pitch of about 1
It is less than μm and the height is less than 0.1 μm.

The processing conditions shown in (b) are as follows:
The bias voltage was -1.5 kV, the irradiation ion current was 10 mA, and the treatment time was 30 minutes.

On the element body 1a which has been subjected to such a surface roughening treatment,
As shown in FIG. 4, the capstan shaft 1 was manufactured by coating the diamond-like thin film 1c and evaluated.

The diamond-like thin film 1c was formed by the apparatus shown in FIG. The basic configuration of this device is
It is the same as that shown in the first embodiment, except that the holder 28 for the capstan shaft adapted to hold the element body 1a in rotation is different.

In the above apparatus, the roughened element body 1a is held by the holder 28 and placed above the ion source 22, and the diamond-like thin film 1c is formed while being rotated by the motor 25. Benzene is used for this source gas,
The diamond-like thin film 1c is formed on the surface of the element body 1a by ionizing 22b and accelerating the same as in the first embodiment.

The film characteristics of the diamond-like thin film 1c vary greatly depending on the film forming conditions. Therefore, in the case of the present embodiment, a bias voltage of −3.0 kV and an irradiation ion current of 1 are set as film forming conditions for forming a relatively hard film with good adhesion.
A film having a thickness of about 0.2 μm was formed under the conditions of 0 mA and a film forming time of 30 minutes.

The diamond-like thin film coated capstan thus formed (hereinafter referred to as capstan)
The evaluation of 1 was performed by measuring the tape driving force.

A method of measuring the tape driving force will be described with reference to FIG. Pinch roller 12 to capstan 11
The magnetic tape 13 is made to travel while applying a constant tape contact force to the magnetic tape 13 and applying a tape tension T to the magnetic tape 13 in the direction opposite to the driving direction R. When the tape tension applied to the magnetic tape 13 is changed, the tape tension value T when a slip of 0.5% occurs between the peripheral speed of the capstan 11 and the running speed of the tape 13 is defined as the tape driving force. did.

Two types of samples evaluated by the above measuring method were prepared by forming a diamond-like thin film 1c on an element body 1a having a different surface roughness, in addition to the capstan shaft 1 treated according to this embodiment. It was used as a comparative example.

FIG. 5 shows surface roughness measurement data of the capstan shaft 1 described above. (A) is the result of the treatment of this example, in which fine irregularities 1b having a height of 10 nm to 100 nm and a pitch of 500 nm to 2 μm are formed on the surface of the element body 1a.
Formed.

(B) is a first comparative example, in which irregularities having roughness of 100 nm in height and 2 μm in pitch are formed on the surface of the element body 1a.

(C) is a second comparative example, in which the surface of the element body 1a is lapped to be a mirror surface, and unevenness smaller than 10 nm in height and 500 nm in pitch is formed.

Further, FIG. 6 shows the above (a), (b), (c).
The photograph of the metal structure of the surface of each capstan shaft 1 shown in FIG.

Then, in FIG. 7, the above (a), (b),
The comparison of the tape drive force by each capstan shaft 1 shown in (c) is shown.

The horizontal axis shows the drive time (aging time) of the magnetic tape, and the vertical axis shows the change in the tape drive force. The pressure contact force of the pinch roller 12 was 600 g. The driving force of this example (a) is the same as that of the first and second comparative examples (b),
It shows the highest driving force as compared with (c), and maintains high driving force even after 1000 hours of driving.

The reason for this result is considered as follows.
In this example (a), as a result of forming the fine irregularities 1b on the element body 1a, the area in contact with the convex portions of the magnetic tape 13 increases, which increases the friction coefficient and improves the driving force.

On the other hand, the first comparative example (b), that is, the one without fine irregularities, in other words, the one with a high density of the convex portions, has a higher convex portion than that of the embodiment (a). The area of the contact between the capstan and the tape becomes smaller as the density of the convex portions becomes lower. Therefore, the friction coefficient is also reduced and the driving force is reduced. In the case of the second comparative example (c), since the element body 1a is a mirror surface, there is no influence of surface roughness, and the friction coefficient and the driving force are determined by the properties of the diamond-like thin film 1c, and the driving is low. Has become.

As is clear from this result, according to the first embodiment of the present invention, the unique coefficient of friction of the diamond-like thin film 1c and the fine unevenness 1 formed on the surface of the element body 1a.
The effect that the tape driving force can be improved by the synergistic action of the wedge effect of b on the tape is obtained.

(Embodiment 2) Next, a second embodiment of the present invention will be described with reference to FIG.

FIG. 8A is a block diagram of an apparatus for forming minute irregularities on the surface of the capstan element body used in the second embodiment of the present invention, which is different from the element shown in FIG. Only the holding frame is different.

In the figure, the holding portion 30 of the element body 1a is composed of a pair of cylindrical members 30a holding both ends of the element body 1a and a central shaft 30b holding these at both ends. And, the central part of the central axis 30b is the argon ion 2
It is installed so as to face the ion source 22 so that the 2a can be directly accelerated and collided. The holding unit 30 is connected to the motor 25, and the plurality of element bodies are rotated at random by the rotation of the holding unit 30.

In the above apparatus, in the same manner as that shown in the first embodiment, the element body 1a has innumerable minute irregularities 1b.
Are uniformly formed.

The processing conditions are as follows: bias voltage -1.5k
V, irradiation in-current 10 mA, treatment time 30 minutes.

FIG. 9 (d) shows surface roughness data of the element body 1a subjected to the surface roughening treatment in this embodiment. For reference,
The surface roughness data of the pre-processed element body 1a is shown in FIG.
In (b), the surface roughness data of what is obtained by simply rotating the body 1a by rotating the holding unit 30 is shown in (c) while applying only the bias voltage without irradiating the argon ions 22a. The surface roughness data of the rotated body 1a are shown.

As is clear from the above data, according to the present embodiment (d), innumerable minute irregularities 1 are formed on the surface of the element body 1a.
It can be seen that b is formed. In addition, this embodiment (d)
It is understood from the comparison between each of the reference examples (a), (b), and (c) that the effect of forming the unevenness 1b on the surface of the element body 1a is obtained by ion irradiation. It is understood that it cannot be obtained only by rolling or applying a bias voltage.

For each of the above-mentioned reference examples (a), (b), (c) and this example (d), a diamond-like thin film 1c was formed on this surface under the same conditions as in the first example, and the tape was prepared. The driving force was evaluated.

The surface roughness of the capstan shaft 1 after forming the diamond-like thin film 1c was measured, and it was the same as that shown in FIG.

Further, in FIG. 10, each reference example (a), (b),
(C) and the surface photograph of this Example (d) are shown, and also FIG.
Table 1 shows the comparison of the tape driving force. As is clear from FIG. 11, the reference examples (a), (b), and (c) show the same tendency without any difference. On the other hand, this embodiment (d) shows a high tape driving force as in the case of the first embodiment. The value of this driving force is shown in FIG.
It can be seen that it is higher than that in (c).

As is clear from this result, according to the second embodiment of the present invention, the tape driving force is improved by the synergistic effect of the diamond-like thin film 1c and the surface roughness as in the first embodiment. The effect of being able to do is obtained.

(Embodiment 3) Next, a third embodiment of the present invention will be described.

Using the apparatus shown in the second embodiment, a plurality of element bodies 1a on which minute irregularities 1b are formed are prepared, and diamond-like thin films 1c of several kinds of hardness are formed on them. Tape drive evaluation was performed. The hardness of the diamond-like thin film 1c can be controlled by changing the bias voltage applied to the element body 1a. The types of the diamond-like thin film 1c are (a) Vickers hardness of 1500 kg / mm ² , (b) 3000 kg / mm ² , and (c) 600.
Films were formed on three kinds of 0 kg / mm ² and the tape driving force characteristics were comparatively evaluated.

The results are shown in FIG. Of (a),
That is, if the hardness of the diamond-like thin film 1c is low, the surface of the capstan 1 is easily worn, and the tape driving force is reduced to the level of the conventional one. It is considered that this is because the diamond-like thin film 1c has a soft film quality and cannot maintain the shape of the unevenness 1b on the surface of the element body 1a.
Also, the one of (c), that is, the diamond-like thin film 1
When c was extremely hard, the diamond-like thin film 1c peeled off due to its own internal stress. As a result, the metal of the element body 1a of the capstan shaft 1 was exposed and the tape driving force was extremely reduced. In order to maintain the shape of the fine irregularities 1b in the present invention, the hardness of the diamond-like thin film 1c (c)
It is desirable to make it harder than that of (b), and the value of (b) showed the best characteristics.

(Fourth Embodiment) Next, a fourth embodiment of the present invention will be described.

Using the apparatus shown in the second embodiment, a plurality of element bodies 1a on which minute irregularities 1b are formed are prepared, and a silicon-containing thin film is formed as an intermediate layer of the diamond-like thin film 1c. Then, a diamond-like thin film 1c having several kinds of hardness was formed thereon, and its driving force was evaluated. The silicon-containing thin film is formed by using the apparatus shown in FIG. 3, and tetramethylsilane (TMS) is used as a raw material.
A film having a thickness of about 50 nm was formed by the same method as the film formation of c. The film forming conditions are a bias voltage of −3.0 kV and an ion current of 1
The current was 0 mA and the film formation time was 15 minutes. Further subsequently, a diamond-like thin film 1c having several kinds of hardness was formed.
The types of the diamond-like thin film 1c are (a) Vickers hardness of 1500 kg / mm ² , and (b) 3000 kg /
mm ² and (c) 3 of 6000 kg / mm ²
The type is the same as that of the third embodiment. Then, the tape driving force characteristics were comparatively evaluated.

The results are shown in FIG. In the case of (c), peeling occurred in the third example, but by forming a silicon-containing thin film on the intermediate layer, the adhesiveness was improved and the peeling did not occur. In addition, since the hardness is the highest, the driving force is higher than those of (a) and (b). On the other hand, (a),
The tape driving force of (b) was not much different from that of the third embodiment.

As is apparent from the above description of each embodiment, according to the magnetic tape driving device and the method of manufacturing the capstan shaft thereof of the present invention, the fine irregularities 1b are formed on the surface of the element body 1a, and By forming the diamond-like thin film 1c on the surface, the tape driving force can be further improved while maintaining the characteristics of the conventional capstan coated with the diamond-like thin film.

In the present embodiment, the charged particles to be irradiated are ionized argon of an inert gas, but the charged particles are not limited to active or inactive, and are not limited to gas.
For example, electrons may be used, and all charged particles can be used.

Further, in each embodiment, the fine unevenness 1b is formed.
The apparatus for forming the diamond-like thin film 1c or the silicon-containing thin film is formed by using a different apparatus, but by using the same chamber and exchanging only the holding portion of the element body 1a. It is also possible to manufacture continuously.

Further, the concavo-convex forming treatment of the present invention is difficult to be realized by the conventional mechanical finishing method, and can be easily realized only by the method shown in this embodiment. Moreover, if the method described in this embodiment is used, it is possible to collectively process a large amount of capstan shafts and the mass production effect is very high.

[0063]

As is apparent from the above description, according to the present invention, the tape driving force of the capstan shaft coated with the diamond-like thin film can be further improved,
In addition, it is possible to provide a magnetic tape drive device excellent in mass productivity and having high industrial value, and a method for manufacturing the capstan shaft thereof.

[Brief description of drawings]

FIG. 1A is a schematic configuration diagram of a surface roughening device used in a first embodiment of a method of manufacturing a magnetic tape driving device of the present invention, and FIG. 1B is a perspective view of the main part.

FIG. 2A is a graph of the surface roughness of a capstan axial element before roughening, and FIG. 2B is a surface roughness of the capstan axial element after roughening according to the first embodiment. Graph

FIG. 3 is a schematic configuration diagram of a diamond-like thin film forming apparatus used in the first embodiment.

FIG. 4A is a perspective view of a capstan shaft of a magnetic tape driving device of the present invention, and FIG.

FIG. 5A is a graph of the surface roughness of the capstan shaft according to the first embodiment, and FIG. 5B is a graph of the surface roughness of the capstan shaft of the first comparative example in comparison with FIG. c) is a graph of the surface roughness of the capstan shaft of the second comparative example.

6 (a) is a photograph showing the metallographic structure of the surface of the capstan shaft corresponding to FIG. 5 (a), and (b) is a photograph showing the metallographic structure of the surface of the capstan shaft corresponding to FIG. 5 (b). 5 (c) is a photograph showing the metallographic structure of the surface of the capstan shaft corresponding to FIG. 5 (c).

FIG. 7 is a comparative characteristic diagram of the tape driving force in the first embodiment.

FIG. 8A is a schematic configuration diagram of a rough surface treatment apparatus used in the second embodiment, and FIG. 8B is an exploded perspective view of essential parts of the drawing.

FIG. 9A is a graph of the surface roughness of a capstan shaft element before roughening treatment. FIG. 9B is a surface roughness of the capstan shaft element when the capstan shaft element is simply rotated. (C) is a graph of the surface roughness of the capstan shaft element when the capstan shaft element is rotated by applying a bias voltage. (D) is the surface roughness after the second embodiment. Graph of surface roughness of capstan shaft element

10A is a photograph showing a metallographic structure on the surface of the capstan corresponding to FIG. 9A, and FIG. 10B is a photograph showing a metallographic structure on the surface of the capstan corresponding to FIG. 9B. 9D is a photograph showing the metallographic structure of the surface of the capstan corresponding to FIG. 9C, and FIG. 9D is a photograph showing the metallographic structure of the surface of the capstan corresponding to FIG. 9D.

FIG. 11 is a comparative characteristic diagram of the tape driving force in the second embodiment.

FIG. 12 is a comparative characteristic diagram of the tape driving force in the third embodiment.

FIG. 13 is a comparative characteristic diagram of tape driving force in the fourth embodiment.

FIG. 14A is a side view of a main part of a conventional magnetic tape drive device, and FIG.

[Explanation of symbols]

 1 Capstan Axis 1a Capstan Axis Element (element) 1b Micro unevenness 1c Diamond thin film 12 Pinch roller 13 Magnetic tape

Claims (4)

[Claims] 1. A capstan shaft for driving a magnetic tape, and a pinch roller for press-contacting the magnetic tape to the capstan shaft, the capstan shaft having a height of 10 nm or more on a surface of a capstan shaft body. A magnetic tape drive device, wherein fine irregularities having a pitch of 100 nm or less and a pitch of 500 nm or more and 2 μm or less are formed, and a diamond-like thin film is formed on the irregular surface. 2. The magnetic tape drive device according to claim 1, wherein the Vickers hardness of the diamond-like thin film is 3000 kg / mm ² or more. 3. The magnetic tape drive device according to claim 1, wherein a thin film layer containing silicon is formed between the uneven surface of the capstan shaft and the diamond-like thin film. 4. The capstan shaft element is irradiated with charged particles while rolling a plurality of capstan shaft elements so as to be in contact with each other, and fine irregularities are formed on the surface of the capstan shaft element by the irradiation. A method of manufacturing a capstan shaft for a magnetic tape drive, the method comprising: forming.