JPH102815A - Noise reduced type tension detecting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To separate and remove a mechanical noise by passing only the ac component of the detection signal of a tension detector by an AC coupling part, reversing it by a reversion arithmetic amplifier, and adding the reversed output to the detection signal. SOLUTION: The detection signal of a detector is inputted from an input end 11, only its ac component is passed by the capacitor C of an AC coupling part, and outputted from a buffer 10. A reversion arithmetic amplifier 20 reverses and amplifies the input signal in an amplification factor of R2 /R1 , and the amplification factor is set to about 1 so that the extracted A.C. component offsets the A.C. component of the detection signal. An adding arithmetic amplifier 30 adds the detection signal and output inputted through an input resistance R3 , respectively, together. In general, R4 /R3 is set to about 10-20 to have an amplification factor of about 10-20, and a current amplification is performed to output a tension signal from which noise component is removed from an output end 12. According to this method, a mechanical noise can be surely removed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a noise reduction type tension detecting device which can easily obtain a desired tension signal from a detection signal in which mechanical vibration or vibration due to resonance is superimposed as noise on the desired tension signal.

[0002]

2. Description of the Related Art In recent years, in order to improve production efficiency, the machine speed tends to increase. In addition, machines tend to be lighter for cost reduction. For this reason, troubles that have not occurred conventionally have come to occur.
One of the troubles is that machine vibration, especially resonance in a certain speed band, occurs due to the speeding up and weight reduction of the machine, and a tension detector that detects the tension of this machine includes:
Mechanical noise such as mechanical vibration is superimposed on the original tension signal and detected, and the mechanical vibration changes depending on the operation speed, and the noise changes according to the change. Therefore, when the machine is controlled based on the tension detection signal, proper control cannot be performed.

[0003]

For this reason, there is a method of applying a low-pass filter to the detection signal to remove mechanical noise composed of high-frequency components. The output value that has just been subjected to the frequency pass filter changes in accordance with a change in noise due to a change in operating speed. For this reason, a case may occur where a low-frequency tension signal cannot be detected correctly.

The present invention has been made in view of the above problems, and has as its object to provide a noise reduction type tension detecting device for separating and removing mechanical noise mixed in a tension detecting signal. .

[0005]

In order to achieve the above object, according to the present invention, a tension detector for detecting a tension and outputting a detection signal, and an AC cup for passing only an AC component included in the detection signal are provided. A ring unit, an inverting operational amplifier for inverting the output of the AC coupling, and an adding operational amplifier for adding the output of the inverting operational amplifier and the detection signal.

The mechanical noise generated by the vibration mixed in the tension signal is mostly an AC component having a large frequency. Therefore, a detection signal in which an AC component is superimposed on a low-frequency tension signal indicating a tension is passed through an AC coupling capacitor to separate the AC component, and the separated AC component is output through a buffer. Next, the output of the buffer is inverted by an inverting operational amplifier, and the inverted AC component and the detection signal are added by an addition operational amplifier, whereby the AC component is canceled out, and a tension signal can be obtained.

According to the present invention, a tension detector for detecting a tension and outputting a detection signal, an AC coupling unit for passing only an AC component included in the detection signal,
A differential operational amplifier having the coupling output as one input, the detection signal as the other input, the input resistance of each input being the same value, and the bias resistance and the feedback resistance being the same value.

[0008] Only an AC component is extracted from the detection signal by an AC coupling unit, and this is used as one input of a differential operational amplifier, and the detection signal is used as the other input. The input resistance of both inputs is R5, and the bias resistance and feedback resistance are R5.
Assuming that 6, the output of the differential operational amplifier cancels the AC component, and a signal R6 / R5 times the tension signal is obtained.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a tension signal detecting device for a machine. The machine is, for example, a device that conveys a web by a roll, and the tension signal is a tension signal representing the tension generated in the web. The tension signal is superimposed on the vibration generated by the rotation of the roll and the running of the web, and this signal becomes a detection signal. The detector 1 detects this detection signal. The filter 2 removes a mechanical noise component such as vibration from the detection signal and detects a tension signal. Note that T
P1 indicates the output side position of the detector 1, and TP2 indicates the filter 2
Shows the exit side position of.

FIG. 2 is a circuit diagram of the filter according to the first embodiment. The filter 2 includes an AC coupling and a subtraction unit. The AC coupling unit includes a capacitor C and a buffer 10 that pass only an AC component. The subtraction unit includes an inverting operational amplifier 20 and an adding operational amplifier. A detection signal from the detector 1 is input from an input terminal 11, and a tension signal from which a noise component is separated from the detection signal is output from an output terminal 12.

The AC coupling section allows only the AC component of the detection signal to pass through the capacitor C and outputs the signal from the buffer 10. The inverting operational amplifier 20 inverts and amplifies the input signal at an amplification factor R2 / R1. This amplification factor is substantially 1 so that the AC component extracted by the AC coupling unit is canceled with the AC component of the detection signal. The addition operational amplifier 30 adds the detection signal input via the input resistor R3 and the inverted AC component of the inverting operational amplifier 20, respectively. R4 / R3
If = 1, the voltage of the sum of the input signals appears at the output terminal 12. Normally, R4 / R3 = 10-20 and input 10
The output voltage signal is up to 20 times, and current amplification corresponding to the load is performed. Since the operational amplifier has a small capacitance component, there is a slight phase difference between the input signal and the output signal of the amplifier 20.
In some cases, the result may be better if the subtraction is performed in 1.1. At this time, R2 / R1 is set to the ratio.

FIG. 3 shows a signal waveform. (A) shows the time change of the tension generated on the web by the operation signal indicating the tension,
It has a gentle curve. (B) is a mechanical noise due to the vibration generated in the roller and is composed of an AC component. (C) is a detection signal waveform at the position of TP1, which is a composite signal of an AC component of an operation signal and mechanical noise. (D) is an output signal at the TP2 position, which is a tension signal obtained by removing an AC component from the composite signal of (c).

FIG. 4 is a circuit diagram of a filter according to a second embodiment. This filter 2 includes an AC coupling unit and a differential operational amplifier 40.
Is the same as that shown in FIG. Both input resistances of the differential operational amplifier 40 are the same R5, and the bias resistance and the feedback resistance are the same R6. The output of the differential operational amplifier 40 is V3, one input voltage is V1, and the other input voltage is V2.
Then, the following equation holds for the voltage. V3 = (V2-V1) R6 / R5 (1) If a detection signal is used as V1 and the output of the AC coupling unit is used as V2, a voltage value R6 / R5 times the tension signal whose sign is inverted is obtained as the output V3. . If V1 is the output of the AC coupling unit and V2 is the detection signal, the tension signal R
6 / R5 times. If R6 / R5 = 1, a tension signal (sign is negative or positive) is obtained as a voltage. In addition,
Although the waveform of the signal shown in FIG. 3 can be applied to the case of FIG. 4, the signal (d) is obtained by inverting the signal. R
By selecting the values of 5 and R6, an output voltage signal amplified at a desired magnification can be obtained. As in the first embodiment, when the output signal of the AC coupling is set to a value different from 1, for example, 0.9 or 1.1, the two input resistors R5 are set to different values from each other. R
6 and the bias resistor R6 have different values.

In the above-described embodiment, the mechanical vibration noise removal in the tension detecting device has been described. However, if the signal to be obtained is a low-frequency signal and a detection signal in which mechanical vibration noise is superimposed thereon, this detection signal Can easily be extracted. In the above-described embodiment, the detection of tension is described. However, the present invention can be applied to detection of general force and gravity, pressure detection, flow rate detection, and detection of a meandering position of a traveling web.

[0015]

As is apparent from the above description, the present invention reliably removes mechanical noise by extracting an AC component from a detection signal and subtracting the AC component from the detection signal to obtain a tension signal. be able to. The filter of the present invention can be incorporated into the detector when a new detector is manufactured, and if it is difficult to incorporate the existing product into the detector, it can be incorporated into an amplifier or relay terminal box. it can.

[Brief description of the drawings]

FIG. 1 is a diagram showing a tension signal detection device for a machine.

FIG. 2 is a circuit diagram of a filter according to the first embodiment.

FIG. 3 is a diagram showing a signal waveform.

FIG. 4 is a circuit diagram of a filter according to a second embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Detector 2 Filter 10 Buffer 11 Input terminal 12 Output terminal 20 Inverting operational amplifier 30 Addition operational amplifier 40 Differential operational amplifier

Claims (2)

[Claims] 1. A tension detector for detecting a tension and outputting a detection signal, an AC coupling unit for passing only an AC component included in the detection signal, an inverting operational amplifier for inverting an output of the AC coupling, A tension detecting device comprising: an adding operational amplifier for adding the output of the inverting operational amplifier and the detection signal. 2. A tension detector for detecting a tension and outputting a detection signal, an AC coupling unit for passing only an AC component included in the detection signal, and an output of the AC coupling as one input. With the signal as the other input,
A tension detecting device comprising: a differential operational amplifier having the same value of input resistance of each input and the same value of bias resistance and feedback resistance.