JPH04155645A - Tension controller - Google Patents

Abstract

PURPOSE:To adjust a difference of tension between those on the incoming side and on the outgoing side by detecting a load torque of a capstan proportional to the difference of the tension between those on the incoming side and the outgoing side of the capstan to control a drive torque to a supply side reel. CONSTITUTION:A capstan 2 applies a driving force to a tape. A rotational speed detection means 5 generates a rotational speed signal proportional to a rotation cycle of the capstan 2. A rotational speed control means 6 generates a speed control signal varying according to the rotational speed signal. A capstan drive means 7 applies a driving force proportional to the speed control signal to the capstan 2 to change a rotational speed of the capstan 2. The rotational speed signal and the speed control signal are synthesized by a synthesization means 8. A reel control means 9 compares an output of the synthesization means 8 with a predetermined value to output a reel control signal. A winding side reel drive means 15 changes a driving force of a winding side reel 4 according to a reel control signal.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a tension control device suitable for video tape recorders and the like.

2. Description of the Related Art In recent years, various approaches have been taken in response to demands for high-speed response of video tape recorders (hereinafter referred to as VTRs). For example, there are requests for a function that allows high-speed tape feeding while reading images while the tape is wrapped around the capstan.

However, when a thin tape is wound around the capstan and the tape is fed at high speed, the tape becomes susceptible to damage. In order to prevent such damage to the tape, various methods have been proposed to accurately manage the tension applied to the tape during running.

Below, such a conventional tension control device will be explained.

FIG. 5 shows a block diagram of a conventional tension control device.

In FIG. 5, a rotary head (not shown) on the rotary cylinder 16 reproduces video information recorded on the tape 1 while scanning the tape 1.

On the other hand, the tape 1 unwound from a supply reel (hereinafter abbreviated as S IJ-reel) 3 is wound up by a take-up reel (hereinafter abbreviated as T reel 4) 4 via a rotating cylinder 16. A tape 1 is placed between the S reel 3 and the rotating cylinder 16.
A first tension sensor 11 is provided for measuring the tension of.

The output of the first tension sensor 11 is transmitted to the first tension control circuit 12.
The voltage is compared with a reference voltage, subjected to proportional, integral, and differential calculations, and then sent to the supply side reel drive circuit (hereinafter abbreviated as S reel drive circuit) 10a. Supply side reel motor (
The S reel motor (hereinafter abbreviated as S reel motor) 10b generates a drive torque proportional to the output current of the S reel drive circuit 10a, and performs first tension control such that the tension at the installation point of the first tension sensor 11 is constant. A loop is configured. In addition, the S reel drive circuit 10a and the S reel motor
b constitutes a supply side reel drive means (hereinafter abbreviated as S IJ-le drive means) 10.

Furthermore, for the same purpose, a second tension sensor 13 is provided between the rotating cylinder 16 and the take-up side reel (hereinafter abbreviated as T-reel) 4, a second tension control circuit 14, and a take-up side reel 4. A second tension control loop is constituted of a reel drive circuit (hereinafter abbreviated as TIJ-le drive circuit) 15a and a take-up motor (hereinafter abbreviated as TIJ-le motor) 15b.

Incidentally, the T reel drive circuit 15a and the TIJ reel drive circuit 15b constitute a take-up side reel drive means (hereinafter abbreviated as TIJ reel drive means) 15.

Since tension sensors are installed on both the take-up and supply sides, accurate tension management is possible on both the supply and take-up sides, making it possible to achieve stable tape running. be.

Such a tension control loop is known, for example, from Japanese Patent Publication No. 63-53624.

Problems to be Solved by the Invention However, in the above configuration, since it is necessary to provide a tension sensor in the tape running system, there is a problem that the number of parts and the number of assembly steps are increased.

In view of the above problems, it is an object of the present invention to provide a tension control device that does not use a tape tension sensor.

Means for Solving the Problems In order to achieve the above object, the tension control device of the present invention provides tension control for winding the tape unwound from the supply reel onto the take-up reel via a predetermined path. In the apparatus, a capstan that is interposed in the path and applies a driving force to the tape, a rotation speed detection means that generates a rotation speed signal proportional to the rotation period of the capstan, and a rotation speed that changes according to the rotation speed signal. a rotational speed control means for generating a speed control signal to generate a speed control signal; a capstan driving means for applying a driving force proportional to the speed control signal to the capstan to change the rotational speed of the capstan; a synthesizing means for synthesizing speed control signals; a reel controlling means for comparing the output of the synthesizing means with a predetermined value and outputting a reel control signal; A take-up reel driving means for changing the driving force is provided.

Effect of the Invention With the above-described configuration of the present invention, the synthesizing means can obtain a signal proportional to the difference in tension between the inlet and outlet sides of the capstan from the rotational speed signal and the speed control signal. This makes it possible to control the drive torque of the take-up reel without using a tension sensor.

EXAMPLE Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 1 shows a schematic block diagram of a tension control device in one embodiment of the present invention.

In FIG. 1, tape 1.5 IJ-le driving means 10,
The first tension sensor 11, the first tension control circuit 12, and the S reel drive circuit 10asS reel motor 10b are the same as those in the conventional example, so a description thereof will be omitted. Also,
Capstan drive circuit 7a and capstan motor 7
b constitutes a capstan driving means 7.

The feature of this embodiment is that the load torque of the capstan motor 7b is detected by the synthesizing means 8, and the T IJ-ru 4 is controlled by the reel control means 9 so that the load torque is constant.
The point is that a loop is provided to control the driving torque of the motor.

That is, the tape 1 that is run by the capstan 2
In order to maintain the automatic centripetal function of the capstan 2 and stabilize the running of the tape, the tension applied by the T reel 4 must have a difference of 5 to 10 gf between the inlet and outlet sides of the capstan. There is.

If this relationship breaks down, the running of the tape 1 will be disturbed.

First, the speed control loop of the capstan 2 will be explained.

The capstan motor 7b rotates the capstan 2 at a constant speed, and the rotation speed detection means 5 detects the rotation speed of the capstan 2.
The output of a frequency generator (not shown) engaged with the capstan motor 7b is frequency-voltage converted to output a rotation speed signal y proportional to the rotation period of the capstan motor 7b. This rotational speed signal y is compared with a reference value in the rotational speed control means 6, subjected to proportional and integral calculations, and outputted as a speed control signal U.

This speed control signal U is sent to the capstan drive circuit 7a, converted into voltage and current, and supplied to the capstan motor 7b. These rotation speed detection means 5, rotation speed control means 6. A series of loops constituted by the capstan drive circuit 7a and the capstan motor 7b constitute a speed control loop for keeping the rotational speed of the capstan 2 constant.

Next, the operation of the synthesizing means 8 will be explained.

This synthesis means 8 constitutes a state observer, and functions to estimate the load on the capstan motor 7b. A detailed explanation will be given below based on FIG. 2.

FIG. 2 is a control block diagram showing the relationship between the synthesizing means 8 and the capstan motor 7b. In FIG. 2, the part within the broken line represents the capstan motor 7b, and the part within the dashed line represents the combining means 8. Here, Jd is the composite moment of inertia that is the sum of the moment of inertia of the capstan 2 and the moment of inertia of the capstan motor 7b, gmd is the voltage-current conversion gain of the capstan drive circuit 7a, and Ktd is the torque constant of the capstan motor 7b, Kv represents the frequency-voltage conversion gain of the rotational speed detection means 5.

If the rotation speed of the capstan motor 7b is ω, and the output of the rotation speed control means 6 is U, then the capstan drive motor 7b
The equation of motion of is expressed by the following equation.

J d−dω/d t =gmd −K t d−u+
Td...(1) Here, Td is the load torque of the capstan motor, dω
/dt represents the time derivative of ω (for one aircraft).

On the other hand, the output voltage y of the rotational speed detection means 5 is )'=K
v·ω (2) Now, design is made so that the relationship between the inputs U and y of the synthesizing means 8 and the output Td' is given by the following equation.

dω'/dt=gmd-Ktd-u/Jd+7' d
'/J d"g+・(y-y')...(3)y"=
Kv・ω"...
(4) dTd” /dt:ga・(y −y”)
(5) Here, y'', ω', and Td' are internal variables of the synthesis means 8, and are estimated values of y, ω, and Td. Furthermore, g++ ga is a design coefficient.

At this time, the relationship between the load torque Td and its estimated value Td' is given by the following equation.

d2Td”/d t2+(g+/g2)・d Td”
/dt"ga・K v/J d T d' = (g
a・K v/J d )T dWhen this is converted to Laplace, Td' (s)=Td(s)*ωo2/(s2+2ζ(
tl.

・S+ωo2) ...(6).

Here, ω02=g2・Kv/Jd, 2ζω.

=g+/g2.

In this way, the estimated value Td''(S) of the load torque is obtained by detecting the actual load torque Td(s) via the second-order lag element whose band is ω0.The combining means 8 is used as a sensor for detecting the load torque. If considered, the detection frequency band is ω0.This characteristic can be freely changed by changing the value of g++ gs, and the rotation speed control means 6
It has nothing to do with the output U of.

Now, the reel control means 9 compares the load torque Td' (s) detected by the synthesis means 8 with a predetermined value, performs proportional and differential calculations, and outputs T I through the T reel drive circuit 15a.
A driving torque is applied to the J-le motor 15b. This series of operations constitutes a tension control loop that keeps the difference between the inlet tension and the outlet tension of the capstan 2 constant. This will be explained below.

A control block diagram of this tension control loop is shown in FIG.

In FIG. 3, the area within the dashed line indicates the control characteristics of the reel control means 9, and the area within the dashed line indicates the tape 1°T IJ-le motor 1.
5b and T-reel 4 from the driving torque to tape tension.

T reel 4 and tape 1 have the elasticity of tape 1 and S reel 3.
Since the mechanical resonance system is determined by the moment of inertia JT, the transmission characteristic from the torque generated by the T-reel motor 15b to the tension of the tape 1 includes a second-order lag element. Let this resonance frequency be ωn.

The reel control means 9 converts the load torque Td'' of the capstan motor 7b detected by the synthesis means 8 to a desired fixed value Tdo(
That is, the difference value is amplified by a phase compensation filter whose transfer function is k (1+s/ωp).

Now, let the gain intersection frequency of this tension control loop be ωC), and let the magnitude relationship of ωn, ωp, and ωC9ω0 be ωn<ωp<ωC×ω0. ω0 is gl of the synthesis means 8 according to equation (6),
The above relationship can be titrated by adjusting g2. Also, ωC and ω
The following relationship holds true for n and ωp.

(IJ C=(ωn2/ωpDG −
(7) G=(rd/rT)・gmv−Kvv−α・K
-(8) where rd is the radius of capstan 2, r
T is the winding diameter of the T reel, gmT is the T reel drive circuit 1
5a is the voltage-current conversion gain, KTT is the torque constant of the TIJ-ru motor 15b, and α is a coefficient representing the change i in the TIJ-ru 4 from the i force to the tension applied to the capstan 2.

Therefore, ωC can be adjusted by the coefficient k of the reel control means 9, and an open loop transfer characteristic (frequency characteristic) as shown in FIG. 4 can be realized.

On the other hand, the relationship between tension Fs and Tdo is as follows in the configuration shown in Figure 3: Fs=G/(10G)・Tdo/rd
...(10). Therefore, the difference Fs between the inlet tension and the outlet tension of capstan 2 is the input T of the tension control loop.
d.

It is controlled to be a constant value by setting the open loop gain G to a sufficiently large value.

In addition, in the above explanation, the winding diameter rv was fixed, but the winding diameter r
y may be detected and, for example, the gain k of the reel control means may be changed accordingly.

Further, although the explanation has been made using Laplace transform assuming an analog circuit, it may also be realized using a digital circuit or software.

Further, although the operation of the reel control means has been described as only phase compensation, integral compensation may also be used.

Furthermore, since the differential calculation section in the phase compensation filter of the reel control means can be obtained from the synthesis means based on equation (5), the phase compensation filter may be configured using this.

In addition, the present invention is not limited to the above embodiments,
Various modifications are possible.

Effects of the Invention As described above, the present invention controls the drive torque of the supply reel by detecting the load torque of the capstan which is proportional to the difference in tension between the input side and the output side of the capstan.
Moreover, the difference between the inlet tension and the outlet tension of the capstan can be kept constant without using a tape tension sensor. This has the excellent effect of not interfering with the automatic widening function of the capstan, and has great practical effects.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of a tension control device in an embodiment of the present invention, FIG. 2 is a control block diagram showing the configuration of the synthesizing means in FIG. 1, and FIG. 3 is a tension control loop in FIG. 1. FIG. 4 is a Bode diagram showing the open loop control characteristics of the tension control loop in FIG. 3, and FIG. 5 is a block diagram showing the configuration of a conventional tension control device. 1...Tape, 2...Capstan, 3.
...Supply side reel, 4...Take-up side reel, 5
...Rotation speed detection means, 6.Rotation speed control means, 7.Capstan drive means, 8..
Synthesizing means, 9... Reel control means, 15...
- Winding side reel drive means. Name of agent: Patent attorney Akira Okaji and 2 others [Figure 3 Figure 4 M liquid collection → Figure 5 1O mountain 1Ob15bl! H.L.

Claims (1)

[Scope of Claims] A tension control device that winds a tape unwound from a supply reel onto a take-up reel via a predetermined path, comprising: a tension control device that is interposed in the path and applies a driving force to the tape; a rotation speed detection means for generating a rotation speed signal proportional to the rotation period of the capstan; a rotation speed control means for generating a speed control signal that changes in accordance with the rotation speed signal; capstan driving means for applying a driving force proportional to the signal to the capstan to change the rotational speed of the capstan; a synthesizing means for synthesizing the rotational speed signal and the speed control signal; and an output of the synthesizing means. reel control means for comparing the reel with a predetermined value and outputting a reel control signal; and a take-up reel drive means for changing the driving force of the take-up reel in accordance with the reel control signal. tension control device.