JPH04168644A - Vtr tape tension arm mechanism and its control method - Google Patents

Abstract

PURPOSE:To achieve stabilization for fluctuation of a tape by converting fluctuation of tape tension to a rotary fluctuation of an arm and then adjusting the tape tension by controlling the fluctuation. CONSTITUTION:A tension arm 11 changes voltage which is applied to a coil 23 in response to rotary displacement of an arm 11 for controlling suction force of a magnetic fluid 21 and for adjusting tape tension, thus enabling vibration of the tape to be attenuated. Namely, frequency components with a low fluctuation of tape tension are fed back to a reel motor with a signal which is detected from a magnet 16 of the tension arm 11 and a hole element 17 for achieving a constant tension and a high frequency component is attenuated by damper operation according to a control part 20, thus obtaining a stable tape running by reducing fluctuation of VTR tape and a VTR with a stable read/write of tape and a high image quality.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention relates to a VTR tape tension arm mechanism and its control method, in particular, a method for detecting tape tension and controlling the tension by utilizing rotational changes of an arm having a tape kite post. The present invention relates to a VTR tape tension arm mechanism and a control method thereof.

[Conventional technology]

Conventionally, this type of tape tension arm 61 has a supply reel (hereinafter referred to as S reel) 51 as shown in FIG.
A sensor 5 is placed in the running path of the tape 53 sent out to the drum 52 from
5 and controls to keep the tension constant. FIG. 6 shows the structure of a conventional tension arm. In this structure, one end of the arm 61 is rotatably supported by a pin 62, and the other end is provided with a guide post 63 that supports the tape 53, and further,
A magnet 64 is joined to the arm 61.

On the other hand, a Hall element 65 is arranged on the fixed side facing the magnet 64. Further, the arm 61 is provided with a spring 66 that biases it in one direction.

In this structure, when the tape 53 is hung on the guide post 63 and stretched with a constant tension,
The arm 61 is rotationally displaced to a position where the tension and the arm spring 66 are balanced and held at that position. Therefore, due to changes in the running of the tape 53, disturbances, vibrations, etc.,
When the tape tension fluctuates, the arm 61 rotates from the equilibrium position about the pin 62 in response to the tension fluctuation.

On the other hand, the Hall element 65 detects changes in magnetic flux caused by the movement of the magnet 64 that operates together with the arm 61, and feeds back the signal to the reel motor drive to control the tension to be constant.

[Problem to be solved by the invention]

However, in the above-described structure, the vibrations of the plurality of guide posts and various members propagate to the tape and cause the tension arm 61 to vibrate, and the vibrations are detected by the Hall element 65, making it difficult to control the vibrations. The tension arm 61 has the role of detecting variations in tape tension and controlling the motor using servo control to maintain a constant tension. However, in a state where there are many vibration wave number components as mentioned above, it exceeds the servo control band, so
There is a problem with oscillation. tension arm 61
has the function of detecting tension and is also responsible for configuring the running path of the tape. Therefore, if the tension arm 61 vibrates greatly, the tape 53 will move faster than other post guides or the drum 52.
There are problems in that the tape may come off, and furthermore, it may become impossible to read or write between the tape and the head. Furthermore, the VTR requires a loading operation in which the tape 53 is pulled out from a reel or cassette (not shown) and wound onto the drum 52. At this time, the tension arm 61 is moved from position A to position B in Figure 5. It rotates a lot. At this time, when the loading is completed, the inertia of the tension arm 61 itself acts to cause over-shorting, causing the tape 53 to come off the drum 52 or other guide posts.

An object of the present invention is to eliminate such conventional drawbacks and provide a highly reliable VTR tape tension arm mechanism that can be stabilized against fluctuations in the tape and a tape tension control method using the arm mechanism. be.

[Means to solve the problem]

In order to achieve the above object, the VTR tape tension arm mechanism according to the present invention includes an arm, a rotation support section, and a braking section, converts fluctuations in tape tension into fluctuations in rotation of the arm, and converts the fluctuations into rotational fluctuations of the arm. A VTR tape tension arm mechanism that controls and adjusts tape tension, the arm has a post that guides the tape, and the rotation support part rotatably supports the rotation axis of the arm. The braking unit includes a tank, a coil, and a magnetic fluid. The tank is made of a magnetic material, stores a certain amount of magnetic fluid inside, receives the rotation axis of the arm, and has a magnetic fluid including the rotation axis of the arm. It forms a magnetic circuit, and the coil excites the magnetic fluid with a voltage applied from an external circuit. The magnetic fluid is attracted between the rotating shaft of the tank and the arm.
This applies braking force to the rotating shaft of the arm in proportion to the applied voltage.

Further, in the VTR tape tension control method according to the present invention, fluctuations in tape tension are converted into fluctuations in rotation of the arm, and the adsorption force of the excited magnetic fluid is applied to the rotation axis of the arm that guides the tape. This is a VTR tape tension control method that adjusts the tape tension by applying braking force to the rotating shaft. During tape loading, a constant voltage is applied to a coil that excites the magnetic fluid, and when the tape is running, it responds to the rotational displacement of the arm. This changes the voltage applied to the coil.

[Effect]

When voltage is applied to the coil, the magnetic fluid is excited, and an amount of magnetic fluid proportional to the applied voltage is attracted to the rotating shaft of the arm, and a braking force is applied to the rotating shaft of the arm within the closed space inside the tank. It will be done. The voltage applied to the coil is varied depending on the driving state; a constant voltage is applied to the coil during tape loading, and the voltage applied to the coil is varied in response to the rotational displacement of the arm during tape running. This controls the amount of excitation of the magnetic fluid and adjusts the tape tension to suit each case.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a schematic perspective view of a tape tension arm showing an embodiment of the present invention. Figure 2 shows the tape tension arm l! shown in Figure 1! FIG. 3 is a cross-sectional view showing the main horizontal parts.

In the figure, the arm 11 has a rotation shaft 19 at one end rotatably supported by a bearing 18 serving as a rotation support part, and a post 13 for guiding the tape 12 at the other end. Further, the arm 11 is provided with a return leaf spring 15 and a magnet 16. On the fixed side, a stopper 14 for regulating the plate spring 15 and a Hall element 17 are arranged facing the magnet 16.

The braking unit 20 produces a damper effect on the arm 11, and includes a tank 22, a magnetic fluid 21, and a coil 2.
3.

The tank 22 is made of a magnetic material, is installed on the fixed side, stores the magnetic fluid 21 therein, receives the rotating shaft 19 of the arm 11, and forms a magnetic circuit including the rotating shaft 11 of the arm 11. . Further, a yoke 24 is provided inside the tank 22 so as to protrude toward the rotating shaft 19 side of the arm 11, and forms a bottleneck around the rotating shaft 11 for receiving the magnetic fluid.

The coil 23 is wound around the outer periphery of the tank 22, and excites the magnetic fluid 21 through a magnetic circuit using a voltage applied from an external circuit. The voltage applied to the coil 23 is set based on the signal obtained from the Hall element 17, and a constant voltage is also applied.

The excited magnetic fluid 21 is attracted between the tank 22, the yoke 24, and the rotating shaft 19 of the arm 11, and a damper effect is generated to apply a braking force to the rotating shaft 19 of the arm 11.

In the embodiment, when a voltage is applied to the coil 23, the magnetic fluid 21 stored in the tank 22 is moved to the yoke 24.
The arm rotation shaft 19 is excited by the magnetic distribution formed between the tank 22 and the arm rotation shaft 19 and rises from the bottom of the tank 22.
and is adsorbed to the inside of the yoke 24 and the tank 22. As a result, a damper action occurs on the rotating shaft 19 of the arm 11. That is, the amount of magnetic fluid 21 attracted to the rotating shaft 19 of the arm 11 is controlled by the magnitude of the voltage applied to the coil 23, thereby controlling the tampering effect.

As shown in FIG.
By changing the voltage applied to the coil 23 in response to the rotational displacement of the magnetic fluid 21, the adsorption force of the magnetic fluid 21 is controlled and the tape tension is adjusted.

Attenuates vibrations 31 of other posts and even the tape.

32 indicates damped vibration. In other words, the frequency components with low fluctuations in tape tension are caused by the tension arm 11
The signals detected from the magnet 16 and the Hall element 17 are used to control the reel motor's feedback so that it maintains a constant tension.
Attenuation is caused by the tambour effect. In a VTR, there are two tape running modes: play mode,
There are various modes such as high-speed search and fast forward-back, and the frequency components of tape tension fluctuations differ depending on the various modes. Therefore, by changing the voltage applied to the coil 23 of the braking section 20, the damper action is varied. Further, as shown in FIG. 4, in the loading operation in which the tape is pulled out from the reel or cassette and wound around the drum, a constant voltage is applied to the coil in advance to attenuate the tape tension overshoot 41 when loading is completed.

42 indicates damped vibration. The amount of this applied voltage can also be determined experimentally.

Stable tape running can be obtained by the tape tension arm and tape tension control method described above.

In addition, in the magnetic circuit configuration of the braking unit 20, the yoke 24
Although a magnetic circuit such as a plunger solenoid is used, the same effect can be obtained according to the present invention.

〔Effect of the invention〕

As described above, according to the present invention, stable tape running can be obtained by reducing tape fluctuations in a VTR, and as a result, a VTR with stable tape reading and writing and high image quality can be obtained. Furthermore, even in various running modes such as tape loading and fast feed, fluctuations in tape tension can be reduced, which prevents the tape from falling off the guide or drum or breaking the tape ends, resulting in a highly reliable VTR. There is.

[Brief explanation of the drawing]

FIG. 1 is a schematic perspective view showing an embodiment of the present invention, FIG. 2 is a cross-sectional view showing the main part of the tape tension arm mechanism shown in FIG. 1, and FIG. 3 shows the tape during tape running. Figure 4 is a diagram showing a state in which tension fluctuations are attenuated. Figure 4 is a diagram showing a state in which tape tension fluctuations due to overshoot of the tension arm during tape loading are attenuated. Figure 5 is a principle diagram explaining the principle of the tension arm. , FIG. 6 is a perspective view showing a conventional tension arm. 11...Tension arm 12...Tape 13.
...Guide boss 14...Stopper 15...
Return spring 16... Magnet 17... Hall element 18... Bearing 19... Rotating shaft of arm 20... Braking part 21... Magnetic fluid
22... Tank 23... Coil patent applicant NEC Corporation Representative Patent attorney Naka Kanno 1. -Time diagram 4

Claims (2)

[Claims] (1) A VTR tape tension arm mechanism that includes an arm, a rotation support section, and a braking section, converts fluctuations in tape tension into rotational fluctuations of the arm, and controls the fluctuations to adjust the tape tension. The arm has a post that guides the tape, the rotation support part rotatably supports the rotation axis of the arm, and the braking part has a tank, a coil, and a magnetic fluid. However, the tank is made of a magnetic material, stores a certain amount of magnetic fluid inside, receives the arm's rotation axis, and forms a magnetic circuit including the arm's rotation axis, and the coil receives the magnetic fluid from the external circuit. The magnetic fluid is excited by the applied voltage, and the magnetic fluid is attracted between the rotating shaft of the tank and the arm.
A VTR tape tension arm mechanism that applies a braking force to the rotating shaft of the arm in proportion to the applied voltage. (2) Changes in tape tension are converted into changes in the rotation of the arm, and the adsorption force of the excited magnetic fluid is applied to the rotation axis of the arm that guides the tape, applying braking force to the rotation axis of the arm to change the tape tension. A VTR tape tension control method for adjusting, which applies a constant voltage to a coil that excites a magnetic fluid when loading a tape, and changes the voltage applied to the coil in response to rotational displacement of an arm when the tape is running. A VTR tape tension control method characterized by: