JPH056599A - Tape driving device - Google Patents

Abstract

PURPOSE:To provide a tape driving device without slipping even under small pinch roller pressurizing force and capable of driving a tape from a capstan shaft side in the tape driving device driving the tape inserted between the capstan shaft and the pinch roller. CONSTITUTION:A diamond-like thin film 4 is formed to the surface of the capstan shaft 1 rotating at constant speed. The tape 3 is inserted between the capstan shaft 1 forming the diamond-like thin film 4 and the pinch roller 2 and the tape is driven by rotating the capstan shaft 1. The diamond-like thin film functions to the magnetic tape as high friction coefficient material, the slipping of the tape is restrained even when the pressurizing force of the pinch roller 2 is small and the tape driving force from the capstan side is transmitted stably for long period.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tape driving device equipped with a capstan shaft, and is useful for driving a magnetic tape in a magnetic recording / reproducing device.

[0002]

9 (a) and 9 (b) are a plan view and a right side view of a conventional tape drive device in a magnetic recording / reproducing apparatus such as a video tape recorder or a cassette tape recorder. 2 is capstan axis 1
In the state shown in FIG. 2, the two are moved in the direction of and the two are pressed against each other with the magnetic tape 3 interposed therebetween. Pinch roller 2
Is rotatably inserted into the rotation support shaft, and the outer peripheral portion thereof is an elastic body such as rubber. In the illustrated state, the capstan shaft 1 is rotated at a constant speed in the arrow A ₁ direction by a rotation mechanism (not shown), so that the magnetic tape 3 can be driven in the arrow A ₃ direction against the load F.

In this case, the tape driving force for driving the magnetic tape 3 is the frictional force between the pinch roller 2 and the magnetic tape 3 and the frictional force between the capstan shaft 1 and the magnetic tape. It is said that the frictional force between the pinch roller 2 and the magnetic tape 3 dominantly affects the drive of the magnetic tape 3.

For example, on pages 194 to 195 of "Hi-Fi Tape Recorder" (published by Radio Technology Co., Ltd., supervised by Masahiko Morizono, third edition), which is a leading book for designing tape drive systems, the tape driving force is given. Is transmitted from the capstan shaft 1 to the outer peripheral surface 2s in direct contact with the pinch roller 2, and further from the pinch roller 2 to the magnetic tape 3. From this point of view, the tape driving force is According to the width L _p of the pinch roller 2, it is also described that the width L _p of the pinch roller 2 is about twice as large as the tape width L _T in order to obtain a large driving force with a small pressure bonding force. .

Generally, the surface of the metallic capstan shaft 1 is processed into a smooth surface of at least several microns or less, and the pinch roller 2 is an elastic body such as rubber.
Rather than the friction coefficient between the tape and capstan shaft,
The coefficient of friction between pinch rollers and the coefficient of friction between the capstan shaft and pinch rollers are larger.

Therefore, the above-mentioned drive force transmission mechanism, which is considered that the tape drive force is transmitted from the capstan shaft to the pinch roller and from the pinch roller to the tape, has some persuasiveness.

On the other hand, Japanese Patent Application Laid-Open No. 2-199653 describes a structure in which irregularities are formed on the surface of a capstan shaft. That is, in a tape drive body composed of a capstan shaft and a pinch roller, particles having a particle size of 1 to 100 μm are fixed to the surface of the capstan shaft to increase the friction coefficient between the capstan shaft and the tape, and to ensure stable tape running. There is a statement that it can be realized.

In this case, the coefficient of friction between the tape and the capstan shaft will certainly increase, but at the same time the coefficient of friction between the pinch roller and the tape also increases. That is,
As described in JP-A-2-199653, when particles are fixed on the surface of the capstan shaft 1, as shown in FIG. 10, which is an enlarged view of the press contact portion between the pinch roller 2 and the capstan shaft 1, the thin tape 3 is used. Of course, the particles are deformed into a convex shape and bite into the surface of the pinch roller 2. In particular, since the tape thickness for video and audio is at most about ten and several μm, when the particle diameter is several tens of μm, the bite into the pinch roller is surely generated.

Therefore, in the one disclosed in Japanese Patent Application Laid-Open No. 2-199653, the same effect as increasing the frictional force between the pinch roller 2 and the tape 3 is obtained even between the tape and the pinch roller. The resulting friction and therefore the frictional force exerted by the pinch rollers on the tape increases as well.

Therefore, when the main tape driving force is applied to the tape from the pinch roller, even if the particles are fixed to the capstan shaft, the tape driving force is still mainly applied from the pinch roller.

Conventionally, when the magnetic tape 3 is driven, tape slip does not occur, that is, there is no speed difference between the peripheral speed of the capstan shaft 1 and the moving speed of the magnetic tape 3. Therefore, the pressure contact force of the pinch roller 2 to the capstan shaft 1 is usually set to 1 kg or more, and a sufficient tape driving force by friction is obtained.

[0012]

In the equipment such as a video camera using such a conventional tape drive device, there are serious problems described below.

First, the following serious problems were faced in reducing the size and weight of the device. That is, in order to reduce the size and weight of the device, the parts constituting the mechanical portion and the chassis are made small and thin to the limit. Therefore, in this case, if the pressure contact force of the pinch roller has a large value as in the conventional case, mechanical components such as the pinch arm are distorted or warped, which hinders normal operation of the device.

Further, the bearing used for the capstan shaft has also become smaller along with the miniaturization of the equipment, so that the allowable load thereof is also small. For this reason, if the pressure contact force of the pinch roller remains at a large value as in the conventional case, the life of the bearing will be significantly shortened. Therefore, in order to reduce the size and weight of the device, it is an essential requirement to reduce the force for pressing the pinch roller 2 against the capstan shaft 1 as much as possible.

However, in the conventional tape drive,
When the pressure contact force of the pinch roller 2 with respect to the capstan shaft 1 is reduced, a sufficient frictional force for driving the magnetic tape 3 cannot be obtained, and slip occurs between the magnetic tape 3 and the capstan shaft.

This slip can be compensated by controlling the rotational speed of the capstan shaft if it is within a certain allowable limit.

That is, at the time of recording on the magnetic tape 3, a pulse-shaped control signal is recorded at a constant time interval on the end portion in the width direction of the magnetic tape. Then, at the time of reproduction, the rotation speed of the capstan shaft is controlled so that the control signal is detected at the same fixed time interval as that at the time of recording. In other words, when the tape speed becomes slower than the peripheral speed of the capstan shaft due to the tape slip, the rotation speed of the capstan shaft is adjusted so that the control signal becomes the tape speed detected at a constant time interval. The control is performed to increase it beyond the normal value. Such control is performed by, for example, a VHS device of VHS standard.

However, in order to perform this control, it is of course necessary to mount a control system having a sufficient control range with respect to the predicted slip, so that the price of the equipment becomes expensive. Further, in this case, the motor for driving the capstan shaft must also be a motor having a sufficient margin, which is incompatible with downsizing of the device.

The tape slip is essentially unpredictable, and sometimes a slip exceeding the control range may occur. In this case, the device cannot operate normally and the magnetic tape 3 It becomes extremely difficult to drive the vehicle in a stable manner, resulting in significant deterioration in the performance and reliability of the equipment.

Further, the equipment which is premised on such control is
Naturally, there is a slip between the tape and the capstan shaft, so there is a problem that the tape is damaged during long-term use. In addition, the pinch roller is also worn faster, which deteriorates wow and flutter as described later.

The second problem is that the tape driving force is transmitted from the pinch roller. As the material of the elastic material on the outer peripheral surface of the pinch roller that contacts the tape,
Mostly rubber is used. For this reason, it is difficult to process the pinch roller with high accuracy in outer diameter dimension and accuracy in outer diameter shape. Therefore, when the pinch roller is inserted into the rotation support shaft and rotated, the outer peripheral surface of the pinch roller rotates with a considerable shake.

Further, the rubber is liable to deteriorate in dimensional accuracy and shape accuracy due to abrasion caused by sliding friction with a tape or a pinch roller. Furthermore, as the rubber is used, the surface condition of the rubber becomes non-uniform, and the coefficient of friction with respect to the tape or the capstan shaft varies depending on the location of the elastic body surface. Further, it is difficult to obtain rubber having a uniform hardness, and the hardness of the outer peripheral surface of the pinch roller differs depending on the location.

When the tape is driven from the pinch roller side, these various factors are directly transmitted to the tape, so that it is unavoidable that the wow and flutter characteristics are deteriorated. Due to its mechanism of occurrence, this problem occurs even under the condition that a sufficient tape driving force is given and the tape slip does not occur. Essentially, the tape driving force is transmitted from the pinch roller. caused by.

To solve the second problem, the frictional force transmitted from the capstan shaft side to the tape may be equal to or more than the frictional force transmitted from the pinch roller side. The reason is that the capstan shaft is generally made of a hard material such as metal, so high precision machining is easy,
Almost no wear that deteriorates the shape accuracy occurs. Therefore, by making the tape driving force transmitted from the capstan shaft larger than the driving force transmitted from the pinch roller, the influence of the pinch roller driving on the wow and flutter can be reduced.

According to the capstan shaft described in JP-A-2-199653, although the frictional force transmitted from the capstan shaft increases, as described above, the frictional force transmitted from the pinch roller also increases. As a result, the tape driving force is still mainly transmitted from the pinch roller side, and this problem cannot be solved.

SUMMARY OF THE INVENTION In view of the above problems, it is an object of the present invention to provide a tape drive device that can reliably drive a tape with a small pressure contact force and that can reliably drive the tape from the capstan shaft side.

[0027]

In order to solve the above-mentioned problems, a tape drive device of the present invention comprises a capstan shaft that rotates at a constant speed, and an elastic member at least in the peripheral portion of which a magnetic tape is attached to the capstan shaft. A tape drive device comprising a pinch roller that rotates by being pressed into contact therewith, wherein a diamond-like thin film is formed on at least the surface portion of the capstan shaft that contacts the magnetic tape.

[0028]

The diamond-like thin film is a carbon film which is amorphous but has characteristics similar to diamond. The diamond-like thin film is composed of diamond-bonded (SP3 bond) carbon and graphite-bonded (SP2 bond) carbon.
Its properties are closely related to the ratio of diamond and graphite bonds. That is, the more diamond bonds are included, the more closely the film becomes a diamond,
Hardness becomes hard.

Conventionally, the diamond-like thin film is recognized as a low-friction material, but in reality, the coefficient of friction of the diamond-like thin film has a large speed dependence, and the dynamic friction coefficient and the static friction when sliding at an extremely low speed. The coefficient is extremely large.
Moreover, the diamond-like thin film has excellent wear resistance.

Therefore, when the diamond-like thin film is provided on the surface of the capstan shaft that rotates at a relative velocity difference with the tape of almost 0, the diamond-like thin film is a material having a low coefficient of friction, which has been conventionally considered. Instead, it functions as a high-friction material. Therefore, it is possible to secure a sufficient tape driving force even when the pressure contact force of the pinch roller is significantly reduced as compared with the conventional case. Moreover, due to the excellent wear resistance of the diamond-like thin film, this high tape driving force is maintained well for a long time.

By forming the diamond-like thin film having a large coefficient of static friction on the capstan shaft instead of on the pinch roller, the tape driving force can be transmitted from the capstan shaft side to the tape. .

[0032]

Embodiments of the present invention will be described below with reference to FIGS. 1 to 8, constituent elements having the same functions as those in FIG. 9 are designated by the same reference numerals, and the description thereof will be omitted.

FIG. 1 is a plan view showing the configuration of a first embodiment of a tape drive device of the present invention, and FIG. 2 is a front view thereof. In FIGS. 1 and 2, the capstan shaft 1 is made of non-magnetic stainless steel having a Vickers hardness of Hv = 500 kg / mm ² or an iron-based material equivalent to the Vickers hardness. A diamond-like thin film 4 having a hardness of 3000 kg / mm ² is formed with a film thickness of 0.2 μm.

Regarding the method for forming the diamond-like thin film 4, various methods have been reported so far (for example, Japanese Patent Laid-Open No. 62-139873), but in this embodiment, an ionization vapor deposition method (Fine Engineering Society Autumn Meeting of 1989) is used. We used the 3rd volume, P621, of the conference proceedings. The ionization vapor deposition method is a method of making a raw material gas into plasma by utilizing thermoelectrons generated by heating of a filament, and making a film by utilizing ions in the plasma. In this case, in order to form a diamond-like thin film, hydrocarbon gas (for example,
CH _4, C ₆ H ₆₎ is used, in the present embodiment uses a C ₆ H _6.

FIG. 3 shows a comparison of the tape driving force between the apparatus of this embodiment and the conventional apparatus. Regarding the conventional device, the results are shown for the case where the surface of the capstan shaft is hard chrome treated and the case where it is not treated.

The only difference between the device of this embodiment and the conventional device is that the device of this embodiment has a diamond-shaped thin film 4 formed on the capstan shaft 1. The horizontal axis of FIG. 3 is
It is the running time of the magnetic tape in the apparatus of this embodiment, and the vertical axis represents the tape driving force at each running time.

The definition and measuring method of the tape driving force mentioned here are as follows. The pressure contact force of the pinch roller 2 to the capstan shaft 1 is made constant, and the magnetic tape 3 is made to travel while applying a tape load T in the direction opposite to the driving direction. When the tape load T applied to the magnetic tape is changed, the value of T when the relative speed difference (slip) of 0.5% occurs between the peripheral speed of the capstan shaft 1 and the moving speed of the tape 3 is the tape driving force. And

In the conventional apparatus, in order to obtain the tape driving force of 80 g, it was necessary to apply a pressure contact force of about 1.2 Kg between the pinch roller and the capstan shaft, but as shown in FIG. Then, a tape drive force of about 80 g can be obtained with a pressure contact force of 600 g, which is about half that of the conventional case.

In addition, this driving force is extremely stable and hardly changes even after 1000 hours of running.
As described above, in this embodiment, the pressure contact force can be greatly reduced to about half of the conventional one, and the tape driving force can be stably maintained for an extremely long period of time.

On the other hand, in the conventional tape drive device in which the diamond-like thin film is not formed, only an inadequate drive force of only 40 g, which is about half that of the device of this embodiment, is obtained.

The remarkable effects of this embodiment obtained by forming the diamond-like thin film on the capstan shaft 1 are understood as follows.

First, in this embodiment, the main reason why a large tape driving force can be obtained with a small pressure contact force is that the diamond-like thin film functions as a material having a high friction coefficient with respect to the tape.

Diamond-like thin films are generally understood to be low coefficient of friction materials. Certainly, when the dynamic friction coefficient was measured by the method described later, as shown in FIG. 4, when the tape and the diamond thin film were rubbed at a relative speed of about 2 mm / sec, the dynamic friction coefficient between them was 0.15. It is a value of the degree. This value is smaller than 0.2, which is the dynamic friction coefficient between the capstan shaft on which the diamond-like thin film is not formed and the capstan shaft whose surface is subjected to various hardening treatments such as hard chrome treatment and the tape. .

However, as shown in FIG. 4, as the relative velocity between the tape and the diamond-like thin film approaches 0, the friction coefficient shows a drastic change, and the static friction coefficient or the dynamic friction between the diamond-like thin film and the tape. The coefficient is about twice as large as the coefficient of friction between the stainless steel material or the iron-based metal and the tape.

Therefore, in the tape drive device in which the tape is driven at substantially the same speed as the peripheral speed of the capstan shaft, the diamond formed on the surface of the capstan shaft, which was conventionally considered to be a low-friction material. The thin film actually functions as a material having a high friction coefficient. As a result, the tape drive force of this embodiment is about twice as large as that of the conventional one.

Further, as shown in FIG. 3, the reason why the tape driving force is stably maintained over a long period of time is considered to be that the diamond-like thin film is excellent in abrasion resistance and physical stability. .

In this embodiment, as described above, extremely excellent characteristics are obtained by the synergistic effect of the high friction coefficient of the diamond-like thin film and the excellent wear resistance.

The characteristic measurement of FIG. 4 was performed as shown in FIG. That is, the magnetic tape 3 is wound around the pinch roller 2 and the magnetic tape 3 is applied to the capstan shaft 1 at a constant pressure F.
Press with. In this state, a horizontal force is applied to the pinch roller 2 or the capstan shaft 1 to generate a relative constant sliding speed between them. Then, the ratio of the force applied in the horizontal direction and the pressure F was obtained as the friction coefficient at this sliding speed. As the capstan shaft, a plurality of conventional capstan shafts having the same surface condition and the like were prepared, a diamond-like thin film was formed on a part of the capstan shaft, and the capstan shaft was used for measurement as the capstan shaft of this example. Was used as it was as a conventional capstan shaft for comparison.

In the present invention, the diamond-like thin film 4 preferably has a thickness of 0.05 μm or more.
This is a diamond-like thin film 4 on the surface of the capstan shaft.
Although there are some differences depending on the operating conditions of the tape drive unit, after operating for about 1000 hours, 0.05
The thickness of the diamond-like thin film is 0.05 μm or more, and therefore the above 1000
Since the time itself is a life time with sufficient margin,
This is because a practically sufficient life can be obtained. Then, in the present embodiment, it is apparent that the main tape driving force is transmitted from the capstan shaft 1 to the tape 3.

That is, as shown in FIG. 2, in this embodiment, the width L _D of the diamond-like thin film 4 is slightly smaller than the width L _{T of the} tape 3. Also, the surface of the capstan shaft 1 is shown in FIG.
The unevenness like the above is not formed.

Therefore, the contact state between the pinch roller 2 and the magnetic tape 3 and the contact state between the pinch roller 2 and the capstan shaft 1 are not changed by forming the diamond thin film on the surface of the capstan shaft.

Therefore, the great increase in the tape driving force in this embodiment is brought about by the contact portion between the magnetic tape 3 and the diamond-like thin film 4 on the surface of the capstan shaft. Tape drive force of the conventional device shown in FIG.
However, assuming that all are given to the tape from the pinch rollers, the tape driving force transmitted from the capstan shaft 1 to the tape 3 in the apparatus of this embodiment is 80 g-40.
g = 40 g, which is the same value as the driving force transmitted from the pinch roller.

In practice, the tape drive force 40g of the conventional device of FIG. 3 cannot be entirely given by the pinch roller, but is also given by the capstan shaft, and therefore,
The tape drive force provided by the pinch rollers is well below 40 g.

Therefore, of the tape driving force of 80 g in the apparatus of this embodiment, the tape driving force transmitted from the capstan shaft has a value far exceeding the above 40 g. Thus, in the apparatus of this embodiment, more than half of the tape driving force is
It is transmitted from the capstan shaft 1 to the magnetic tape 3,
The main tape drive force is transmitted from the capstan shaft.

Next, a second embodiment of the present invention will be described. The device of this embodiment has the same configuration as that of FIG. However, as shown in FIG. 6 which is a sectional view in the axial direction of the capstan shaft 1, the surface 1 _S is a fine uneven surface having a surface roughness of 0.5 μmR _z , and the surface of this uneven portion has a Vickers hardness.
The diamond-like thin film 4 of 3000 kg / mm ² is formed with a film thickness of 0.2 μm. As the method for forming the diamond-like thin film 4, the ionization vapor deposition method was used as in the first embodiment.

Since the diamond-like thin film has good coverage, in the present embodiment, the surface roughness of the base surface 1 _S is also reflected on the surface of the diamond-like thin film 4 to form irregularities. Therefore, in the device of the present embodiment, the driving force of the tape is further improved by the synergistic effect of the high friction coefficient of the diamond-like thin film 4 and the locking effect due to the unevenness formed on the surface of the diamond-like thin film. Moreover, due to the high wear resistance of the diamond-like thin film, the shape of the uneven portion is maintained even after long-term use, and a high tape driving force can be maintained.

FIG. 7 shows the evaluation results of the running time and the tape driving force of the apparatus of this embodiment in comparison with the conventional example in which the diamond-like thin film is not formed. Tape drive force measurement method,
The measurement conditions and the like are the same as in the case of the first embodiment. As a conventional example, a capstan shaft which is a metal surface having a surface roughness of 0.05 μmR _z or less, a capstan shaft which is a metal surface having irregularities having a surface roughness of 0.5 μmR _z , and a surface roughness of 0. 3 shows three types of capstan shafts having an uneven surface of 5 μm R _{z and} a titanium nitride film having a thickness of 0.2 μm formed on the surface.

In all of the conventional capstan shafts, the tape driving force drastically decreases with the tape running time, and practical life is not obtained at all, whereas in the device of this embodiment in which the diamond-like thin film is formed. , Dramatically increased life,
A significant improvement in driving force has been achieved. In FIG. 7, it is considered that the tape driving force of the conventional capstan shaft having the unevenness formed on the surface thereof is sharply decreased because the unevenness of the surface is rapidly worn as the tape runs.

In the present invention, the surface roughness of the capstan shaft 1 is set to 0.1 μmR _{z to 2} μmR _z, and the thickness of the diamond-like thin film is 0.1 μm or more and the surface roughness value of the capstan shaft 1 is set to 0.1 μmR _z or more. (0.5 μm in the above embodiment) or less is more preferable. The reason is that when the surface roughness of the capstan shaft 1 is 0.1 μmR _z or more, unevenness having a sufficient locking effect is formed on the surface of the diamond-like thin film, and when it is 2 μmR _z or less, it is excessive. This is because it is possible to prevent the tape from being damaged by such unevenness.
Further, by setting the thickness of the diamond-like thin film to 0.1 μm or more, it is guaranteed that the diamond-like thin film will not be worn out even after a long time operation of about 1000 hours, and the value of the surface roughness of the base By making the film thickness smaller than that, the surface roughness of the underlayer is reflected on the surface of the diamond-like thin film, and the unevenness effective for increasing the tape driving force can be well formed on the diamond-like thin film surface. .

Further, in this embodiment, the adhesion of the diamond-like thin film can be increased by the unevenness of the capstan shaft surface. Therefore, it is effective when forming a diamond-like thin film having a particularly high Vickers hardness. That is, as the Vickers hardness of the diamond-like thin film is increased, the internal stress of the film increases and the adhesion with the capstan shaft decreases. This tendency is particularly strong when the Vickers hardness is 3500 kg / mm ² or more. However, in this example, since the surface is provided with the uneven portion, the contact area between the shaft and the diamond-like thin film is widened, and the adhesive force due to the Van der Waals force acting between them increases to improve the adhesiveness. Of.

Next, a third embodiment of the present invention will be described.
In the tape drive device of each of the above embodiments, the length L _D of the diamond-like thin film formed on the surface of the capstan shaft can usually be determined mainly by the required tape drive force. For example, L _D may be short if the required tape driving force is small.

Normally, L _D may be determined in this way from the viewpoint of the required tape driving force. However, when the tape driving device of the present invention is used in, for example, a video device, the length L _D of the diamond-like thin film is more than L _{T as} shown in FIG. 8 in relation to the tape width L _T. It is more preferable to increase the length. The reason is as follows.
If L _D is shorter than L _T as shown in FIG. 1, the end surface 3 _{E of the} tape contacts the metal surface of the capstan shaft 1,
The central portion of the tape comes into contact with the diamond-like thin film 4 formed on the capstan shaft.

As described above, the diamond-like thin film and the metal surface of the capstan shaft differ in friction coefficient with respect to the tape by about twice. Therefore, when the tape is driven, a large imbalance occurs in the frictional force applied to the end surface portion 3 _E and the central portion of the tape, and when the same tape is repeatedly run in such a state, for example, the tape central portion and the end surface portion Due to the difference in the amount of elongation of the tape, wrinkles or the like are likely to occur on the end surface portion 3 _{E of the} tape, or the wrinkles thus produced are likely to cause further deformation or damage of the tape. As is well known, in the case of a video tape recorder, the end surface of the tape is not only a reference for running along the lead portion of the cylinder, but also a portion where a control signal is recorded. When an inconvenience occurs, the tape running becomes unstable, the tracking linearity deteriorates, and the compatibility in recording and reproducing decreases.

On the other hand, when L _D is made larger than L _T as shown in FIG. 8, the entire tape including the end face portion 3 _E uniformly contacts the diamond-like thin film. The parts also receive substantially the same driving force, the above-mentioned inconvenience is avoided, and the reliability of the device can be further enhanced.

By making L _D larger than L _T in this way, the safety and reliability when the same tape is repeatedly run can be further improved. Therefore, the end surface of the tape is not limited to video equipment. The present embodiment is particularly effective for a device that is driven by abutting a section on a tape running guide provided in a tape running system or a device in which a signal is recorded at the tape end part.

Further, in each of the above embodiments, the ionized vapor deposition method was used for forming the diamond-like thin film, but the film forming method is not limited to these in the present invention.
Further, in order to further improve the adhesion of the diamond-like thin film, Ti is provided between the capstan shaft and the diamond-like thin film.
An intermediate layer of NC, TiC, Si, SiC, etc. may be provided. Alternatively, as described in JP-A-2-274876, it is possible to increase the adhesive force of the diamond-like thin film by forming the diamond-like thin film in the initial stage of formation under a condition of small internal stress and gradually changing the film quality. is there.

In the tape drive device of the present invention, the diamond-like thin film formed on the capstan shaft has a Vickers hardness of Hv = 1500 kg / mm ² or more and a specific resistance of 1.0 × 1.
More preferably, it is 0 ⁴ Ωcm or less. At a Vickers hardness of 1500 kg / mm ² or more, practically sufficient abrasion resistance can be obtained, and the tape driving force can be stably maintained for a long period of time. Also, by setting the specific resistance to less than 1.0 x 10 ⁴ Ωcm, the generation and accumulation of static electricity on the tape can be suppressed and prevented, and noise can be effectively prevented when reproducing the signal recorded on the tape. it can.

Further, by actually using the tape drive device of each of the above embodiments in a VHS standard VTR camera, the size and weight of the VTR camera could be greatly reduced. Further, in this case, the tape traveled at almost the same speed as the peripheral speed of the capstan shaft without slipping, and the wow and flutter was improved compared with the conventional one, and the running characteristics were remarkably improved.

Further, it was confirmed that the magnetic tape runs at almost the same speed as the peripheral speed of the capstan shaft with a sufficient margin even without using the tape drive control system as described in the conventional example. As described above, the present invention enables the cost reduction of the device by greatly simplifying or omitting the conventional tape running control system described above.

Further, it is obvious that the same effect can be obtained not only in the VTR camera but also in other devices for driving the tape.

[0071]

As described above, according to the present invention, it is possible to realize a tape drive device which can obtain a sufficient tape drive force even if the pressure contact force of the pinch roller is small. It is possible to achieve no tape running.

Further, in the present invention, since the diamond-like thin film is formed not on the pinch roller surface but on the capstan shaft surface, the main tape driving force can be transmitted from the capstan shaft and the wow and flutter A great effect can be exerted on the improvement.

Since the diamond-like thin film is formed on the capstan shaft, the tape drive device can be easily manufactured. That is, the diamond-like thin film is formed in a vacuum and at a considerably high temperature. Therefore, it is usually difficult to form a diamond-like thin film on the surface of a pinch roller formed of an elastic body such as rubber from the viewpoint of heat resistance temperature and vacuum resistance of the elastic body. Since the diamond-like thin film is formed on the shaft, heat resistance and vacuum resistance do not pose any problems, and it is possible to form the diamond-like thin film with high quality and stability extremely easily.

Further, even if a diamond-like thin film can be formed on the surface of the pinch roller, the surface of the pinch roller is
Each time it is pressed against the capstan shaft, it deforms greatly and large stress is repeatedly generated in the diamond-like thin film on the surface,
Although peeling of the diamond-like thin film occurs, it is clear that such an inconvenience does not occur in the present invention.

As described above, by forming the diamond-like thin film on the capstan shaft, a high quality tape drive device can be easily manufactured.

In addition, the present invention has an extremely high industrial value because it is an important technique for simplifying and omitting the tape running control system.

[Brief description of drawings]

FIG. 1 is a plan view showing the configuration of a first embodiment of the present invention.

FIG. 2 is a front view showing the configuration of the first embodiment of the present invention.

FIG. 3 is a characteristic diagram of tape driving force in the first embodiment of the present invention.

FIG. 4 is a characteristic diagram showing a dynamic friction coefficient.

FIG. 5 is a front view of a dynamic friction coefficient measuring device.

FIG. 6 is a sectional view showing the configuration of a second embodiment of the present invention.

FIG. 7 is a characteristic diagram of tape driving force in the second embodiment of the present invention.

FIG. 8 is a front view showing the configuration of a third embodiment of the present invention.

FIG. 9A is a plan view showing a configuration of a conventional tape drive device, and FIG. 9B is a right side view of the tape drive device.

FIG. 10 is a side view showing the configuration of another conventional tape drive device.

[Explanation of symbols]

1 capstan shaft 2 pinch rollers 3 magnetic tape 4 Diamond-like thin film

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Hideaki Yoshio             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. (72) Inventor Hideyuki Hashi             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. (72) Inventor Yuu Nakamura             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd.

Claims (6)

[Claims] 1. A tape drive comprising a capstan shaft having a diamond-like thin film formed on the surface thereof, and a pinch roller which is made of an elastic member at least on its peripheral surface and is rotated by pressure contact with the capstan shaft via a magnetic tape. apparatus. 2. A capstan shaft, and a pinch roller, at least a peripheral portion of which is made of an elastic member, is pressed against the capstan shaft via a magnetic tape to rotate, and at least a magnetic tape on the surface of the capstan shaft. The contact portion is provided with unevenness having a surface roughness of 0.1 μmR _{z to} 2.0 μmR _z , and at least the surface of the unevenness has a film thickness of 0.1 μm.
A tape drive device on which the above diamond-like thin film is formed. 3. The diamond-like thin film has a Vickers hardness of Hv15.
The tape drive device according to claim 1 or 2, which has a weight of at least 00 kg / mm ² . 4. The diamond-like thin film has a specific resistance of 1.0 × 10 ⁴ Ω.
3. The tape drive device according to claim 1, which is smaller than cm. 5. The tape drive device according to claim 1, wherein the diamond-like thin film has a thickness of 0.1 μm or more. 6. A tape drive device according to claim 1, wherein the width of the diamond-like thin film formed on the capstan shaft is larger than the tape width.