JPH0668553A - Reel base torque delivery device - Google Patents

Abstract

PURPOSE:To prevent a damage to a tape due to an excess tension or unstable drive of the tape due to a deficient tension by controlling the tape winding tension to be always optimum and constant in the normal reproduction mode, the fast feed reproduction mode, the rewinding reproduction mode and the video recording mode. CONSTITUTION:A motor 23 is driven depending on the quantity of a tape winding tension detected by a tension sensor 3a at a supply reel side to rotate an energizing force variable gear 26 through gears 24, 25. Since a female thread provided in the inside of the gear 26 meshes with a male thread provided on a shaft 14, the gear 26 changes an amt. of compression of a press spring 28 through its own rotation. Since the change in the amt. of compression results in controlling a friction between a driving body 11 and a driven body 12, the tape tension sensor 3a at the supply reel side directly detects the tape winding tension. Thus, the tape winding tension is always kept optimum and constant.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reel base driving force transmission device for maintaining constant tape tension in a magnetic recording / reproducing apparatus and preventing tape damage or unstable running of tape due to fluctuations in tape tension.

[0002]

2. Description of the Related Art In recent years, magnetic recording / reproducing devices such as tape recorders have tended to be smaller and lighter, and tape cassettes used in these magnetic recording / reproducing devices have been downsized and recorded for a long time. In order to increase the recording capacity of information that can be recorded in a tape cassette, there is an increasing number of cases where a tape having a small tape thickness is used.

The conventional magnetic recording / reproducing apparatus will be described below.
The structure of the reel driving force transmission device will be described.

FIG. 3 is a plan view of a main part of a conventional magnetic recording / reproducing apparatus, showing a tape cassette, a tape path formed by a tape pulled out from the tape cassette, and a drive system for running the tape. ing. 4 is a sectional view taken along the line B-O ₁ -O ₂ -B in FIG. 3, and particularly shows the structure of the reel driving force transmission device in detail.

In FIGS. 3 and 4, 1 is a tape cassette, 2 is a tape, 4 is a tape abutting against the tape 2 from the inside, and the tape 2 is pulled out from the opening of the tape cassette 1 and the path of the tape 2 from the outside is regulated. Forming a tape path by making contact with the post 6 which forms a tape path, and 7 is the tape 2
Capstan for running the car at constant speed, 8 is tape 2
A pinch roller for pressing the capstan 7 against the capstan 7, a pulley 9 provided coaxially with the capstan 7 and rotating at the same rotational speed as the capstan 7, a square belt 10 driven by the pulley 9 and transmitting the rotation to the driving body 11a, Reference numeral 12a is a driven body whose rotation is transmitted by the driving body 11a via the slip member 13, and rotatably supports the driving body 11a. Reference numeral 12b is a gear portion provided on the driven body 12, 14a is a shaft which is planted in the chassis 15a and rotatably holds the driven body 12a, and 16 is a drive member 11a and a slip member 13
A biasing spring 16 that is pressed against the driven body 12a via
Reference numeral a is a spring seat for transmitting the urging force of the urging spring 16 to the driving body 11a, and 17 is a swing arm that rotates about the shaft 14a, and is rotatably held by the shaft 19 with the swing gear 20 and driven. The gear portion 12b of the body 12a and the swing gear 20 are kept at a constant interval so as to be properly meshed with each other.
Further, the swing arm 17 includes the driven body 12a and the shaft 14.
Insert the slip member 18 between it and the flange part of a,
According to the rotational direction of the driven body 12a, the frictional force between the driven body 12a and the slip member 18 causes the shaft 14a to rotate clockwise or counterclockwise. Swing arm 17
The pivoting gear 20 is engaged with either the gear portion 21a of the feeding side reel base 21 or the gear portion 22a of the winding side reel base 22.

The operation of the conventional magnetic recording / reproducing apparatus constructed as described above will be described with a focus on the reel driving force transmitting apparatus.

As shown in FIG. 3, the tape 2 drawn from the tape cassette 1 by a plurality of posts 4 and wound around the cylinder 5 is pressed against the capstan 7 by the pinch roller 8, and a motor not shown is shown. The capstan 7 is rotated by this and the tape 2 is fed. At this time, the rotation of the capstan 7 is transmitted to the square belt 10 by the pulley 9, and the operation of the square belt 10 causes the driving body 11a to rotate. The driver 11a is the slip member 1
3, the rotation of the driving body 11a is transmitted to the driven body 12a via the slip member 13, and the rotation of the driven body 12a is driven by the biasing spring 16. It is transmitted to the swing gear 20 via the gear portion 12b of the body 12a. At this time, the driven body 12
The rotation of a is performed by the swing arm 17 via the slip member 18.
On the other hand, since the rotation is transmitted in the same direction as the rotation of the driven body 12a, the swing arm 17 rotates clockwise or counterclockwise according to the rotation direction of the driven body 12a.
When the swing arm 17 rotates clockwise, the swing gear 20 meshes with the gear portion 22a of the take-up reel stand 22 to rotate the take-up reel stand 22 in the winding direction of the tape 2. Let On the other hand, when the swinging arm 17 rotates counterclockwise, the swinging gear 20 meshes with the gear portion 21a of the feeding-side reel base 21, and the feeding-side reel base 21 is attached to the tape 2.
Rotate in the winding direction.

As described above, when the take-up reel stand 22 or the feed-side reel stand 21 is rotating in the winding direction of the tape 2, the capstan 7 is always rotating at a constant speed. The take-up side reel stand 22 or the feeding side reel stand 21 so as not to apply slack or excessive tension.
In order to rotate, the slip member 13 is inserted between the drive body 11a and the driven body 12a to cause slippage therebetween.

[0009]

However, in the above-mentioned conventional structure, the reel torque for winding the tape is substantially constant in the normal recording / reproducing mode, the fast-forward reproducing mode and the rewinding reproducing mode. When the winding diameter of the tape changes from the minimum value to the maximum value, the tape tension for winding the tape changes from the maximum value to the minimum value. This relationship is shown in FIG.

When a tape cassette is mounted on a magnetic recording / reproducing device equipped with a conventional frictional driving force transmitting device and a tape is wound on a reel stand, the tape winding torque of the reel stand on the side where the tape is wound is T Assuming that the tape winding diameter on the tape winding side is r and the tape tension on the reel output side (tape tension between the winding reel and the nearest post, hereinafter simply referred to as winding tension) is t, the tape winding tension t is , T = T / r. Here, since the tape winding torque T of the reel stand is almost constant, the relationship between the tape winding diameter r on the tape winding side and the tape winding tension t becomes a curve shown in FIG.

Here, the minimum value of the tape winding radius (winding radius at the beginning of tape winding) is rmin, the maximum value of the tape winding radius (winding radius at the end of tape winding) is rmax, and the minimum value of the tape winding tension is tmin, When the maximum value of the tape winding tension is tmax, the relationship of tmax / tmin = rmax / rmin is established.

In a magnetic recording / reproducing apparatus equipped with a conventional frictional driving force transmitting apparatus, the tension ratio tma is
When x / tmin becomes large to some extent, the tape winding diameter r on the tape winding side becomes r in the rewinding reproduction mode.
In a state close to min, that is, in a state in which the tape winding diameter is close to the minimum value, the tape winding tension t is close to tmax, the tape winding tension t becomes too large, and tape damage occurs, or the tape is not applied to the cylinder. In some cases, the contact pressure becomes excessive and good reproduction cannot be performed. On the other hand, the tape winding diameter r on the tape winding side is rm
In a state close to ax, that is, in a state where the tape winding diameter is close to the maximum value, the tape winding tension t is close to tmin,
The tape winding tension t becomes too small, the normal winding function is not fulfilled, and the tape running may become unstable.

Further, since the driving force of the driving body is transmitted to the driven body by utilizing a substantially constant frictional force, energy loss proportional to the difference in rotational speed between the driving body and the driven body occurs, and the difference in rotational speed occurs. There is also a problem in that the power transmission efficiency becomes very poor when is large.

The present invention is intended to solve the above problems, and it is possible to control the reel torque so that the tape winding tension is substantially constant irrespective of the tape winding diameter on the tape winding side. It is also an object of the present invention to provide a magnetic recording / reproducing apparatus equipped with a reel base driving force transmission device that has good power transmission efficiency even when the difference in the number of rotations between the driving body and the driven body is large.

[0015]

In order to achieve the above object, a reel base driving force transmission device according to the first means of the present invention used in a magnetic recording / reproducing device is provided with a driving body which is driven by a motor and rotates. A reel base driving force transmission device that includes a driven body that transmits power to a reel base, presses the drive body and the driven body to transfer rotational force by friction, and urges the drive body to the driven body. The tape tension is provided with an urging means and a friction transmission force control means for controlling the transmission force due to friction from the driving body to the driven body by changing the urging force of the urging means to an arbitrary value. And a tape tension value detected by the tension detecting means for controlling the transmission force due to friction from the driving body to the driven body.

Further, in the reel base driving force transmission device according to the second means of the present invention, the reel rotation speed is replaced with the tension detecting means for detecting the tape tension in the reel base driving force transmission device according to the first means. It is provided with a reel rotation speed detecting means for detecting, and is configured to control the transmission force due to friction from the driving body to the driven body by the reel rotation speed value detected by the reel rotation speed detecting means. is there.

[0017]

According to the first means, since the tension detecting means for detecting the tape tension is provided, it is judged from the value of the tape tension whether the transmission force due to the friction from the driving body to the driven body is proper. The frictional force between the driving body and the driven body, which determines the transmission force due to the friction between the driving body and the driven body, is adjusted by the frictional transmission control means, and the frictional force between the driving body and the driven body is adjusted. By controlling the frictional force between them, the drive torque of the reel can always be kept at an optimum value, and the tape tension can be made optimum and constant.

According to the second means, the running speed of the tape is known when the pinch roller is in pressure contact with the capstan via the tape, and the reel rotation speed detection means detects the rotation speed of the reel base. Is known, the winding radius of the tape on the reel is calculated, and the winding radius of the tape on the reel is calculated, so that the frictional force between the driving body and the driven body can be reduced by winding the tape on the reel. It becomes possible to control to a value suitable for the radius, the drive torque of the reel can always be kept at an optimum value, and the tape tension can be made optimum and constant.

[0019]

1 and 2 show an embodiment of the present invention.

FIG. 1 is a plan view showing a main part of an embodiment of a magnetic recording / reproducing apparatus of the present invention. A tape cassette and a tape path formed by a tape pulled out from the tape cassette, and the tape runs. The drive system to be driven is shown.
FIG. 2 is a sectional arrow view taken along the line AO ₁ -O ₂ -A in FIG. 1, and particularly shows the structure of the reel driving force transmission device of the present invention in detail.

1 and 2, FIGS. 3 and 4
The same parts or parts as those shown in are attached with the same reference numerals, and therefore description thereof will be omitted, and different parts will be described.

In FIG. 1, a tension sensor 3a on the supply reel side detects the tape winding tension on the supply reel side in the rewinding reproduction mode or the like.
A tension sensor 3b on the take-up reel side detects the tape take-up tension on the take-up reel side in the normal recording / playback mode. The tension sensor 3a
And 3b are used in the first embodiment.

Next, 29a is a rotation speed sensor for detecting the rotation speed on the supply reel side, and 29b is a rotation speed sensor for detecting the rotation speed on the take-up reel side.
a and 29b are used in the second embodiment.

Further, in FIG. 2, reference numeral 11 denotes a driving body that rotates by transmitting the rotation of a pulley 9 that rotates at the same rotation speed as the capstan 7 by a square belt 10, and 12 denotes a driving body 11 through a slip member 13. A driven body that is rotated by transmission of rotation, 12b is a gear portion provided on the driven body 12, 14 is a rotary shaft that is planted in a chassis 15 that coaxially and rotatably supports the drive body 11 and the driven body 12, 23 is a motor for varying the drive torque, 24 is a motor 23
Output gear attached to the output shaft of the, output gear 2
4 is an intermediate gear that connects the biasing force variable gear 26, and 27 is a screw for moving the biasing force variable gear 26 up and down.
4 is provided with a male screw and the variable biasing force gear 26 is provided with a female screw. A biasing spring 28 is held between the variable biasing force gear 26 and the spring receiving seat 28a, and the spring receiving seat 28a is pressed against the driving body 11 by the biasing spring 28.

First, the operation of the reel base driving force transmission device having the above structure will be described. In this description, the operation in the rewinding reproduction mode that is greatly affected by the tape winding tension will be described.

In the rewinding reproduction mode, the tape 2 is wound around the feeding reel, so that the capstan 7 rotates counterclockwise. The pulley 9 coaxial with the capstan 7 also rotates in the counterclockwise direction, and the driving body 11 coupled with the pulley 9 and the square belt 10 also rotates in the counterclockwise direction. Since the driving body 11 presses the driven body 12 via the slip member 13 by the urging force of the urging spring, the driven body 12 also rotates counterclockwise. Part of the rotational force of the driven body 12 is transmitted to the swing arm 17 via the slip member 18, the swing arm 17 rotates counterclockwise, and the swing arm 17 is rotatably held by the shaft 19. The swinging gear 20 thus swung revolves around the shaft 14 as the swinging arm 17 rotates, and meshes with the gear portion 21a of the feed reel stand 21. Since the swing gear 20 meshes with the gear portion 12b of the driven body 12, it rotates clockwise with the rotation of the driven body 12 and meshes with the gear portion 12b of the driven body 12. The gear portion 21a of 21 is driven by the clockwise rotation of the swing gear 20, and the feeding-side reel base 21 rotates counterclockwise. Therefore, the tape 2 is wound around the feeding side reel base 21.

In the first embodiment of the present invention, the tension sensor 3a on the supply reel side in the rewinding reproduction mode.
However, since the tape winding tension on the supply reel side is detected, the driving body 1 is determined from the value of the tape winding tension.
It is possible to determine whether the transmission force due to friction from 1 to the driven body 12 is appropriate. By controlling the frictional force between the driving body 11 and the driven body 12, the reel driving torque can be always kept at an optimum value, and the tape tension can be made optimum and constant.

That is, the motor 23 is driven according to the magnitude of the tape winding tension detected by the tension sensor 3a on the supply reel side, and the biasing force variable gear 26 is rotated via the gear 24 and the gear 25. Since the urging force variable gear 26 has a female screw provided inside thereof meshing with a male screw provided on the shaft 14, the urging force variable gear 26 rotates the urging force variable gear 26 itself so as to generate a compression margin of the urging spring 26. Change. Since changing the compression margin of the biasing spring 28 controls the frictional force between the driving body 11 and the driven body 12, the tension sensor 3a on the supply reel side.
By directly detecting the tape winding tension,
The motor 23 can control the frictional force between the driving body 11 and the driven body 12 to keep the tape winding tension always optimum and constant. The tension sensor 3
It is possible to detect the tension by a or 3b and keep the tape winding tension optimum and constant not only in the rewinding reproduction mode but also in the normal reproduction mode, the fast-forward reproduction mode and the recording mode. .

On the other hand, when the pinch roller is in pressure contact with the capstan via the tape, the running speed of the tape is known, and if the number of rotations of the reel base 21 on the supply reel side is known, the reel is moved to the reel. The tape winding radius is calculated. Therefore, in the second embodiment of the present invention, the rotation speed of the reel stand 21 on the supply reel side is measured by the rotation speed sensor 29a that detects the rotation speed of the supply reel side, thereby measuring the rotation speed of the reel stand. is doing. If the number of rotations of the reel stand is known, the tape winding radius on the reel can be calculated, and by calculating the tape winding radius on the reel, the reel drive torque suitable for the winding radius can be calculated and the driving body The frictional force between the driven body and the driven body can be controlled to a value suitable for the winding radius of the tape on the reel, and the tape winding tension can always be kept optimum and constant. It should be noted that it is not limited to the rewinding reproduction mode, and it is not limited to the rewinding reproduction mode that the tape winding tension is always optimal and constant by obtaining the required driving torque of the reel from the measured value of the rotation speed of the reel stand. The same is possible in the fast-forward reproduction mode and the recording mode.

As described above, according to the reel base driving force transmission device of the present invention, the reel rotation driving torque can be controlled in both the first embodiment and the second embodiment. It is possible to always keep the tape winding tension optimal and constant. Further, when the rotational speed difference between the driving body and the driven body is large, the frictional force between the driving body and the driven body is controlled to be small, so that the rotational speed difference between the driving body and the driven body becomes large. Also, an increase in energy loss can be suppressed, and a reel base driving force transmission device with good transmission efficiency can be obtained.

[0031]

As is apparent from the above description, according to the reel base driving force transmission device of the present invention, the normal reproduction mode,
In the fast-forward playback mode, the rewinding playback mode, and the recording mode, the tape winding tension can always be optimally and constantly controlled in both the first embodiment and the second embodiment. Even if the tape winding radius changes from the maximum value to the minimum value, the tape winding tension does not change, it is possible to prevent tape damage due to excessive tension, and prevent unstable running of tape due to insufficient tension. , Good characteristics and high reliability can be obtained.

Further, when the rotational speed difference between the driving body and the driven body is large, the frictional force between the driving body and the driven body is controlled to be small, so that the friction between the driving body and the driven body is reduced. The force is controlled to be necessary and minimum, the energy loss due to friction between the driving body and the driven body is small, and high energy efficiency is obtained.

[Brief description of drawings]

FIG. 1 is a plan view of a main part of a magnetic recording / reproducing apparatus including a reel base driving force transmission device according to an embodiment of the present invention.

2 is a sectional view taken along the line AO ₁ -O ₂ -A of FIG.

FIG. 3 is a plan view of a main part of a magnetic recording / reproducing apparatus including a conventional reel base driving force transmission device.

4 is a sectional view taken along the line B-O ₁ -O ₂ -B of FIG.

FIG. 5 is a characteristic diagram showing a relationship between a winding reel tape winding radius and a winding reel tension.

[Explanation of symbols]

 3a, 3b Tension detection means 11 Drive body 12 Follower bodies 21, 22 Reel stand 23 Motor (friction transmission force control means) 24 Output gear (friction transmission force control means) 25 Intermediate gear (friction transmission force control means) 26 Variable biasing force Gear (friction transmission force control means) 27 Screw (friction transmission force control means) 28 Biasing spring (biasing means) 29a, 29b Reel rotation speed detecting means

Claims (3)

[Claims] 1. A reel base drive comprising a drive body driven by a motor to rotate and a driven body for transmitting power to a reel base, wherein the drive body and the driven body are brought into pressure contact with each other to transfer a rotational force by friction. A force transmission device, comprising: biasing means for biasing the driving body to the driven body and friction from the driving body to the driven body by changing the biasing force of the biasing means to an arbitrary value. A reel base driving force transmission device comprising: friction transmission force control means for controlling transmission force. 2. A tape tension detecting means for detecting a tape tension at a predetermined position, and a reel base driving force transmitting means for transmitting a rotation of a driving body to a driven body by friction. The tape tension detected by the tension detecting means. The transmission force of the friction transmission force control means is controlled by the value.
The reel base driving force transmission device described. 3. A reel rotation speed detecting means for detecting the number of rotations of the reel, and a reel base driving force transmitting means for frictionally transmitting the rotation to the driven body by the driving body, which are detected by the reel rotation speed detecting means. The transmission force of the friction transmission force control means is controlled by the reel rotation speed value.
The reel base driving force transmission device described.