JPH05334765A - Tension controller - Google Patents

Abstract

PURPOSE:To provide a method for constituting a tension control system having sufficient suppression effect for the disturbance of a frequency synchronized with the rotation of a reel due to the winding unevenness, etc., of a tape. CONSTITUTION:The output of an integrator 16 integrating and outputting respectively the output of a pressure senser 14 obtaining a voltage signal in proportion to the tension of the magnetic tape 1 at every rotational angle of a first reel 2 detected by a magnetic flux detection element 6 and the output of a high band differential filter 15 differential-processing the high band frequency component of the output of the pressure senser 14 are added by a drive circuit 17. Then, current in proportion to the output is supplied to a first motor 3 directly coupled with the first reel 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tension control device used in a tape running system such as a video tape recorder (hereinafter referred to as VTR).

[0002]

2. Description of the Related Art In a device such as a VTR for pulling a magnetic tape from a reel and recording / reproducing a signal, the magnetic tape is pulled out in order to make the contact state between the magnetic tape and the magnetic head uniform and to perform stable magnetic recording / reproducing. It is required that the tension of the magnetic tape be constant. Further, making the tension of the magnetic tape constant is also required in order to reduce damage to the magnetic tape.

Therefore, conventionally, in order to stabilize the tension of the magnetic tape, the tension of the drawn magnetic tape is detected, and the torque of the motor is fed back to the motor for directly driving the reel wound with the magnetic tape. The tension of the magnetic tape is stabilized by controlling it.

In order to ensure the stability of the control system,
When the detected value of the tension of the magnetic tape is returned to the motor, a lead lag filter or the like is used to perform differential processing on the high frequency component, that is, phase lead compensation (for example, "VTR Design Latest Technical Documents" Nihon Kogyo). Technology Center).

[0005]

However, in order to sufficiently suppress the tension fluctuation due to the winding unevenness of the magnetic tape wound on the reel and the torque ripple of the motor for directly driving the reel, the tension of the magnetic tape is reduced. It is necessary to increase the gain when returning the detected value to the motor and increase the control band, but because of the noise component contained in the differentiated signal in the lead-lag filter, stable differentiation processing is possible even in the high frequency range. It was difficult to realize, and it was difficult to stabilize the tension control system sufficiently.

In the present invention, attention is paid to the fact that tension fluctuations caused by uneven winding of the magnetic tape wound on the reel and torque ripple of the motor for directly driving the reel occur in synchronization with the rotation of the reel, and the stability is impaired. It is an object of the present invention to provide a tension control device capable of sufficiently suppressing the tension fluctuation caused by these.

[0007]

To achieve this object, the tension control device of the present invention draws the tape from the first reel on which the tape is wound and winds the tape on the second reel. In this device, tension detecting means for detecting the tension of the tape being pulled out, a motor for driving the first reel, and N number of rotation angles of the first reel are divided into substantially equal parts (N: Natural number)
Rotation angle detecting means for detecting a rotation angle of the input signal, a high-frequency differential filter for differentiating a high-frequency component of the input signal by using the output of the tension detecting means as an input signal, and the rotation angle detecting means for detecting An integral for adding and integrating outputs of the tension detecting means at each of the N rotation angles of one reel for each of the N rotation angles and outputting the integration result according to each of the N rotation angles. And a drive circuit that supplies electric power to the motor in proportion to the result of adding the output of the high-frequency differential filter and the output of the integrator with a predetermined gain.

[0008]

According to the tension control device of the present invention, the output of the tension detecting means at each of the N rotation angles of the first reel detected by the rotation angle detecting means is added and integrated for each rotation angle to perform the rotation. By the integrator that outputs the integration result according to the angle, the tension fluctuation that changes according to the rotation angle of the first reel is separately suppressed for each rotation angle. That is, tension fluctuations due to uneven winding of the tape wound on the first reel and torque ripple of the motor for driving the first reel occur in synchronization with the rotation of the first reel. Tension fluctuations caused by this are sufficiently suppressed.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A tension controller according to an embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of a tension control device according to an embodiment of the present invention.

In FIG. 1, a magnetic tape 1 is pulled out from a first reel 2 by a capstan shaft 11 and a pinch roller 12 which rotate at a substantially constant speed, through a post 7, a rotary drum 9 and a post 10 and then a first reel 2. It is wound up by the second reel 13. A magnetic head is mounted on the rotary drum 9, and the magnetic tape 1 is subjected to helical scan recording or reproduction. The first reel 2 is connected to the first motor 3 via the concentric shaft 4.
Are directly connected, and the first motor 3 directly drives the first reel 2. Further, a multipolar magnetized magnet 5 is attached to the concentric shaft 4. The magnet 5 is the first motor 3
With the rotation of the first reel 2, the magnetic flux detecting elements 6 arranged facing each other generate a pulse signal according to the rotation angle. Here, the magnet 5 is magnetized with 6 poles and detects the first, second and third rotation angle positions every 120 degrees for one rotation of the first reel 2 and generates a pulse signal.

A pressure sensor 14 is arranged between the posts 7 and 8. The pressure sensor 14 is pressed by a pressing force proportional to the tension of the magnetic tape 1, and outputs a voltage signal proportional to this pressing force. That is, the pressure sensor 14 can obtain a voltage signal proportional to the tension of the magnetic tape 1.

The high-frequency differential filter 15 receives the output voltage signal of the pressure sensor 14, amplifies a component having a predetermined frequency (here, 4 Hz) or more with a gain slope of 6 dB / oct, and outputs the amplified component. In such a frequency range from 0 Hz to 4 Hz, the gain is asymptotically 0 dB,
The differential filter having a gain slope of 6 dB / oct asymptotically in the above frequency range is a general-purpose operational amplifier and a resistor,
It is well known that it can be easily realized by a capacitor.

Further, the integrator 16 outputs the output voltage of the pressure sensor 14 each time the output pulse signal of the magnetic flux detecting element 6 arrives, that is, at the first, second and third rotation angle positions of the first reel 2. The signal is integrated and output for each rotational angle position. Such an integrator 16 is specifically realized as shown in FIG.

FIG. 2 is a configuration diagram showing a specific configuration of the integrator 16. Pressure sensor 14 input from terminal 20
The output voltage signal of is converted into a digital signal by the A / D converter 21 and input to the digital adder 22. The digital adder 22 outputs a digital signal from the A / D converter 21 and a shift register 29 (details will be described later).
The output digital signal of is added and output. The output of the digital adder 22 is input to the digital filter 23. The digital filter 23 is a low-pass filter that processes an input digital signal, removes high-frequency components, and outputs the result. The output digital signal of the digital filter 23 is converted into an analog signal by the D / A converter 24 and output from the terminal 25.

The output digital signal of the digital filter 23 is input to the shift register 27 and is input to the terminal 2
It is delayed each time the pulse signal output from the magnetic flux detecting element 6 input from the 6 arrives. Similarly, the shift register 28 delays the output of the shift register 27 at each arrival of the pulse signal output from the magnetic flux detecting element 6 input from the terminal 26,
The shift register 29 delays the output of the shift register 28.

That is, in this configuration, since the magnetic flux detecting element 6 outputs three pulse signals per one rotation of the first reel 2, the first and second magnetic flux detecting elements 6 detected by the shift register 29 are: The result of addition and integration of the outputs of the pressure sensor 14 at the respective rotation angle positions of the second and third rotation angle positions will be output.

Now, referring to FIG. 1, the high frequency differential filter 1
5 and the output signals of the integrator 16 are output from the drive circuit 17
Entered in. The drive circuit 17 adds two input signals at a predetermined gain ratio (here, 1: 1) and supplies a current proportional to this to the first motor 3.

The control characteristics of the tension control device of the present embodiment constructed as above will be described. FIG. 3 shows FIG.
FIG. 3 is a control block diagram of the tension control device in the present embodiment shown in FIG. 2, and is a transmission from the disturbance torque fluctuation T when the disturbance torque fluctuation T is applied to the first reel 2 to the tension fluctuation Ft of the magnetic tape 1. It represents a characteristic. In the figure, S represents a Laplace operator.

A block 31 represents transmission from a torque change applied to the first reel 2 to a rotation angle fluctuation θ of the first reel 2. J is the sum of the inertial moments about the concentric shaft 4 of the first reel 2, the magnetic tape 1 wound on the first reel 2, the rotor of the first motor 3, and the magnet 5.

A block 32 represents transmission from the rotation angle fluctuation θ of the first reel 2 to the length fluctuation X of the magnetic tape 1 in the longitudinal direction. r is the winding radius of the magnetic tape 1 wound on the first reel 2. Block 33 represents transmission from the length variation X of the magnetic tape 1 in the longitudinal direction to the tension variation Ft of the magnetic tape 1. Ct is the compliance of the magnetic tape 1.

A block 34 represents the detection sensitivity of the tension of the magnetic tape 1 by the pressure sensor 14, and Kf is its gain. Block 35 represents the transmission of the high pass differential filter 15. T1 is a time constant of the high frequency differential filter 15. Blocks 36, 37 and 38 represent the transfer of the integrator 16. Block 36 represents the transmission of the digital filter 23, T2 being its time constant.

The block 37 is a shift register 27, 28.
And 29, where L is the time required for the first reel 2 to make one revolution. Block 38 represents the transfer of digital adder 22. Note that the integrator 16 is a discrete system, but here, for convenience, it is expressed as an approximately equivalent continuous system. Blocks 39 and 40 represent the drive circuit 17 transmission. Block 39 represents adding the output of the high pass differential filter 15 and the output of the integrator 16.

A block 40 represents the voltage-current conversion characteristic of the drive circuit 17, and gm is a voltage-current conversion coefficient. Block 41 represents the transmission up to the generated torque Tm when the input current I of the first motor 3 is applied, and Kt is the torque constant of the first motor 3. A block 42 represents the operation by the negative feedback by the tension control device of the present embodiment when the disturbance torque fluctuation T is added, and the torque Tm generated by the first motor 3 is added in a polarity so as to cancel the disturbance torque fluctuation T. It means that.

FIG. 4 is a Bode diagram showing the characteristic of the transfer function from the disturbance torque fluctuation T to the tension fluctuation Ft of the magnetic tape 1 when the disturbance torque fluctuation T of the tension control device in this embodiment is applied. The horizontal axis represents the frequency of the disturbance torque fluctuation T, and the vertical axis represents the transfer gain from the disturbance torque fluctuation T to the tension fluctuation Ft of the magnetic tape 1.
In FIG. 4, as an example, the winding radius of the magnetic tape 1 wound on the first reel 2 is such that it takes 2 seconds for the first reel 2 to rotate once, and such tape speed is also set. Represents the transfer characteristics when the magnetic tape 1 runs. That is, it represents the transfer characteristic when L in block 37 of FIG. 3 is 2 seconds.

A solid line 43 is a transfer gain curve from the disturbance torque fluctuation T of the tension control device in this embodiment to the tension fluctuation Ft of the magnetic tape 1. Also, the solid line 44
Is a transfer gain curve from the disturbance torque fluctuation T to the tension fluctuation Ft of the magnetic tape 1 when the integrator 16 is removed in the tension controller of the present embodiment. That is, the transfer gain curve represented by the solid line 44 equivalently shows the transfer gain curve of the conventional tension control device.

As is apparent from FIG. 4, according to the tension control device of the present embodiment, the transfer gain from the disturbance torque fluctuation T to the tension fluctuation Ft of the magnetic tape 1 at the frequency synchronized with the rotation of the first reel 2. Is a minimum point, which is sufficiently smaller than that of the conventional one, and it can be seen that the tension of the magnetic tape 1 is not easily influenced by the disturbance torque fluctuation T. Here, as an example, the first reel 2 is 1
It is the winding radius of the magnetic tape 1 wound on the first reel 2 which requires 2 seconds to rotate, and the case where the magnetic tape 1 runs at such tape speed is shown.
When the winding radius and the tape speed of the magnetic tape 1 wound on the first reel 2 have different values, the value of L in the block 37 of FIG. 3 is a shift which is a component of the integrator 16 shown in FIG. The transfer gain curve 43 is generated by the functions of the output pulse signals of the magnetic flux detecting element 6 synchronized with the rotation of the first reel 2 inputted from the registers 27, 28 and 29 and the terminal 26.
The frequency of the minimum point at changes in synchronization with each other, and the transfer gain from the disturbance torque fluctuation T to the tension fluctuation Ft of the magnetic tape 1 at a frequency always synchronized with the rotation of the first reel 2 becomes smaller than that of the conventional one.

By the way, most of the disturbances assumed in such a tension control device are the first reel 2
It is caused by uneven winding of the magnetic tape 1 wound on the magnetic tape 1 and torque ripple of the first motor 3 and is synchronized with the rotation of the first reel 2. According to this, the transmission gain for these disturbances becomes a minimum point, sufficient disturbance suppression is performed, and the tension fluctuation of the magnetic tape 1 hardly occurs.

There are various methods for specifically realizing each constituent element of the tension control device in this embodiment, and the present invention is not limited to this structure.

[0029]

As is apparent from the following embodiments, according to the tension control device of the present invention, the transmission gain with respect to the disturbance generated in synchronization with the rotation of the reel on which the magnetic tape is wound becomes a minimum point and sufficient disturbance is obtained. Since the magnetic tape is suppressed, the tension fluctuation of the magnetic tape hardly occurs, and the problem of the conventional tension control device can be solved.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a tension control device according to an embodiment of the present invention.

FIG. 2 is a configuration diagram showing a specific configuration of an integrator 16 of the tension control device of this embodiment.

FIG. 3 is a control block diagram of the tension control device of the present embodiment.

FIG. 4 is a Bode diagram showing the transmission gain up to the tension fluctuation of the magnetic tape with respect to the disturbance torque of the tension control device of this embodiment.

[Explanation of symbols]

 1 Magnetic Tape 2 First Reel 3 First Motor 5 Magnet 6 Magnetic Flux Detection Element 13 Second Reel 14 Pressure Sensor 15 High Frequency Differential Filter 16 Integrator 17 Drive Circuit

Claims (1)

[Claims] 1. A device for pulling out the tape from a first reel on which the tape is wound and winding the tape onto a second reel, wherein the tension detecting means detects the tension of the tape being pulled out, and A motor for driving one reel, a rotation angle detecting means for detecting N rotation angles (N is a natural number) obtained by substantially equally dividing one rotation angle of the first reel, and an output of the tension detecting means are inputted. The output of the tension detecting means at each of the N rotation angles of the first reel detected by the rotation angle detecting means and the high frequency differentiating filter for differentiating the high frequency component of the input signal as the signal is the N An integrator that adds and integrates each of the N rotation angles and outputs the integration result corresponding to each of the N rotation angles; and an output of the high-frequency differential filter and an output of the integrator. Tension control device a power proportional to the result of addition by the gain; and a driving circuit for supplying to said motor.