JPS62276425A - Shape detector - Google Patents

Abstract

PURPOSE:To detect the elongation percentage of an object to be measured with high accuracy, in a shape detector applying external force to the object to be measured cyclically to detect the displacement quantity thereof, by correcting the non-linearity of the displacement of the object to be measured and displacement converted voltage output. CONSTITUTION:Cyclic external force is applied to an object 1 to be measured by an external force applying apparatus 4a and the displacement detection signal obtained by a displacement detector 4b is inputted to a displacement quantity detection part 32. The detection part 32 outputs a displacement quantity detection signal F from which noise is removed and calculates the S/N ratio of the displacement quantity detection signal and an external force applying part 28 is controlled so that the S/N ratio becomes large. The outputted displacement quantity F is inputted to a displacement correction device 29 where the non-linearity of the displacement of the object to be measured and displacement converted voltage output is corrected. The corrected displacement quantity output of each detection part 32 is inputted to a displacement average value operator 30 to calculate the average value of each detection part. An elongation rate operator 30 operates elongation rate from the output of each detection part and the above mentioned average value.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a shape detection device that detects the shape (flatness) of a strip-like object such as an IL steel plate by knowing the tension distribution in its width direction.

[Conventional technology]

In general, when cold rolling a strip, the shape (also called flatness) is important as well as the thickness accuracy. However, in cold rolling, high tension is applied during rolling, so
Due to the elastic elongation of the rolled material, i.e. the strip, even if a flatness defect such as medium elongation or ear waves occurs in this strip, the displacement (unevenness) is reduced or disappears and is usually undetectable. .

Therefore, as mentioned above (with high tension applied, it is not possible to directly detect the poor flatness of the strip, but it is possible to indirectly detect the shape by knowing the tension distribution in the width direction of the strip). It is well known as shown in Japanese Patent Publication No. 53-17071.

In other words, the tension is weak in areas with poor flatness, so the shape can be determined from the tension distribution.

FIG. 5 is a block diagram showing an example of a conventional shape detection device of this type.

1 is an object to be measured, that is, a strip-shaped body, and 2 is a supporting roll, such as a deflector roll, which applies tension to the strip-shaped body 1. 3 is a rectangular wave oscillator as an example of a drive signal generator;
a is an amplifier. Reference numeral 4 denotes a detection head, which is provided along the width direction of the strip-shaped body 1 and spaced apart from the surface of the strip-shaped body 1 at appropriate intervals by appropriate locking means. Rad 4 to this detection
is composed of an external force applying device 4a and a displacement detector 4b. The external force applying device 4a consists of an electromagnet in which an excitation coil B is provided on a magnetic pole A having a U-shaped cross section along the width direction of the strip 1, and the displacement detector 4b is attached to a basic portion C along the width direction of the strip 1. A plurality of cylinders of displacement measuring electrodes are provided facing the surface of the strip 1, and are provided integrally with the external force applying device 4a.

Note that the displacement detector 4b may be provided separately from the external force applying device 4a (also, the external force applying device is not limited to an electromagnet as described above, but may be a device capable of applying force without contact, such as compressed air). 4c is a displacement converter such as a capacitance-to-voltage converter, as shown in FIG. 9 is a signal processing circuit, which includes a polarity switch 5, an integration circuit 6, a sample hold circuit 7, and each of the above-mentioned devices 5, 6.
．． It consists of a timing generation circuit 8 connected to 7,
The timing generating circuit 8 is connected to each of the devices 5, 6, 7 and the square wave oscillator 3, respectively. . For example, the signal processing circuit 9 is connected to a CRT via a display control device 10.
It is connected to a display device 11 such as a monitor. Further, the signal processing circuit 9 can also be connected to the roll crown adjustment device 13 via the roll crown control circuit 12.

Next, the operation will be explained. First, the rectangular wave oscillator 3 generates a rectangular wave with a period Tc as a drive signal. Next, this drive signal is amplified in the amplifier 3a, and this amplified signal is applied as an external force to the surface of the strip 1 via the external force application device f4a, thereby causing the strip 1 to generate a displacement P (x-t). The displacement P (x-t) generated on the surface of the strip 1 is:
This displacement is detected as capacitance by a displacement detection electrode provided in the displacement detector 4b, and converted into a voltage signal by a displacement converter 4C which is a signal converter, that is, a capacitance-to-voltage converter. The plurality of cylinders of displacement detection electrodes provided along the width direction of the strip 1 detect the displacement of each part of the strip 1 in the same way, and the signal converted into a voltage signal is sent to the signal processing circuit 9. is input. After the polarity of the displacement detection signal is switched by a polarity switch 5, the signal is input to an integrating circuit 6, where it is integrated for each rectangular wave period. As a result, noise other than the tension signal is removed, only the portions related to the tension of each part of the object to be measured are calculated, and the integral value thereof is input to the sample and hold circuit 7 and sampled and held. The timing generation circuit 8 controls various timings such as the polarity switching timing of the polarity switch 5, the reset timing of the integrating circuit 6, and the sample-hold timing of the sample-hold circuit 7, based on the reference signal from the square wave oscillator 3. .

The output of the sample and hold circuit 7 is transmitted to a display device 11 such as a CRT monitor via a display device control circuit 10.
displayed and provided for operator monitoring,
Used as data for shape adjustment.

In addition, when performing automatic shape control of the object to be measured, that is, the strip-like object 1, the output of the sample hold circuit 7 is sent via an automatic control system, that is, a roll crown control circuit 12, separately from the display system.
The purpose can be achieved by providing input to the roll crown adjustment device 13.

In the above description, a case has been described in which a rectangular wave signal is used as the drive signal, but the drive signal is not limited to a rectangular wave signal, and signal waveforms such as an M-sequence signal, a random signal, or a sine wave signal may also be used. , and when these signal waveforms are employed, a multiplication circuit may be provided in place of the polarity switch 5 in the signal processing circuit 9.

Furthermore, to explain using a mathematical formula, in Fig. 5, T (x): Tension L per unit width at Displacement P (x
-t) is expressed as. Further, assuming that the Tl1 equation is the displacement detection signal, the output C(x-nTc) of the sample-and-hold circuit 7 is expressed as follows.

Tc: Period of the rectangular wave n: Number of cycles of the rectangular wave Further, the external force r(t) per unit width is a rectangular wave with an amplitude a, and can be expressed as follows.

Therefore, assuming that equation (3) is also an electrical signal amount, the output value C (x-nTc) from the sample-and-hold circuit 7 is calculated from the above (1).
.

It follows from equations (2) and (3). Here, the second term in equation (4) is the effect of disturbance, but it can be considered that if the rectangular wave period Tc becomes large, it will be sufficiently smaller than the stationarity of the irregular vibration d(t) of the band-shaped body 1. The above equation (4) is expressed as follows, and further, from this equation (5), the width direction coordinate
The tension per unit width T (x) at can be expressed as and the tension is measured.

Next, the content of equation (4) above is realized. The signal waveforms of each signal processing section in the circuit of FIG. 5 will be explained with reference to FIG. 6.

In FIG. 6, (al indicates a rectangular wave signal generated by the rectangular wave signal generator 3, n is a positive integer,...
m −2+ . . . 1m+1 . . . are each position that n takes.

In FIG. 6, (bl is O of the period Tc by the external force applying device 4a.
The alternating current waveform of the displacement signal when the strip 1 is displaced by applied external forces of N and OFF is shown.

(C) in Figure 6 is the disturbance signal component at point ■ due to irregular vibrations of the band-shaped body, and the random noise signal due to this vibration is superimposed on the displacement signal (1) in Figure 5 above. is the signal with the waveform shown in FIG. 6(d), and the displacement converter 4C
This is the signal waveform at point @ indicating the output of , and the signal at point 0, which is the output of changer 6, is obtained as the waveform of (e) in FIG.

When this is integrated by the integrator circuit 6 over a period from nTc to (n+1)Tc, a signal with a waveform of (fl) shown in FIG. 6, which is the signal at the 0 point, is obtained as an output.
At time c, the sample and hold circuit 7 displays (f) in FIG.
When the signal at point 1 is sampled and held, a signal at point 0, which is the output of the sample and hold circuit 7, is obtained as shown in FIG. 6(g).

As is clear from the above equation (4) and the signal processing waveform in FIG. 6, the output (phantom) of the shape detection device is obtained every rectangular wave period Tc.

[Problem that the invention seeks to solve]

Since the conventional shape detection device is configured as described above, the output response is determined by the rectangular wave period Tc for periodically applying an external force to the object to be measured, and by shortening the rectangular wave period Tc. The response must be fast, but
Although the noise caused by irregular vibrations of the object to be measured can be removed by increasing the rectangular wave period Tc, the lower limit of the period Tc is also limited, and there is a problem that the response cannot be made faster. The ratio between the first and second terms in equation (4) can be expressed as an S/N ratio (signal/noise ratio), and the magnitude of this S/N ratio affects the detection accuracy of the shape of the object to be measured. Generally speaking, the irregular vibration d(t) of the measured object changes its amplitude and frequency depending on the magnitude of the tension, including the external force, applied to the measured object. Therefore, the S/N of the output of the signal processing circuit is determined by the tension value applied to the measured object.
Since the ratio changes, the S/N ratio is affected by the tension value applied to the object to be measured, and even if the amount of disturbance due to irregular vibration changes, it is possible to ensure detection accuracy accordingly. Furthermore, as expressed by equation (5), the output signal C(x-nTc) is inversely proportional to the tension distribution T(x) of the measured object, and the amplitude a corresponding to the applied external force is Because it is proportional, even if the flatness of the object to be measured is the same, the output will change depending on the tension and external force applied to the object to be measured, so when the purpose is to control the flatness of the object to be measured, This is extremely inconvenient, and for the purpose of controlling the flatness of the object to be measured, there is a problem that even the same flatness results in different outputs, and
A displacement converter, which is a capacitance-to-voltage converter, is used as a means of detecting the displacement of the object to be measured, and its distance characteristics (displacement characteristics) are shown in Fig. 4 between the object to be measured and the displacement detector. The output of the displacement converter when the distance (displacement) changes from ioms to 9 cranes is 50 mV, but from 10 m to 711
When the voltage changes to , it becomes 200 mV instead of 150 mV. In other words, the output characteristics of the displacement transducer always have the same sensitivity per unit displacement with respect to displacement. The signal processing circuit processes the output of this displacement transducer. Instead of integrating the displacement P (X - t) in equation (1) above, the signal obtained by converting the displacement P (x - t) into voltage according to the characteristics shown in Figure 4 is integrated using equation (2) above. Therefore, in equation (5) above, a correction coefficient according to the displacement must be taken into consideration.Since this correction coefficient is not taken into consideration, the reciprocal of the tension distribution of the measured object and the applied external force must be There were problems such as not being able to obtain an accurately proportional output and resulting in inaccurate tension distribution detection.

This invention was made in order to solve the above-mentioned problems.The invention was made in order to solve the above-mentioned problems. Since the output with noise removed can be obtained, high response can be achieved.The noise level caused by irregular vibrations of the measured object can be measured, and the applied external force can be controlled to ensure a sufficiently high displacement signal of the measured object compared to the noise level. By using iTJ, it is possible to achieve high accuracy, and it also converts the output into the elongation rate of the object to be measured, so that even if the tension or applied external force changes, if the flatness of the object to be measured is the same, the elongation rate remains the same. It is an object of the present invention to provide a shape detection device that can obtain a highly accurate elongation rate by adding a function to correct the nonlinear characteristics of a displacement transducer.

[Means for solving problems]

The shape detecting device according to the present invention detects displacements at N locations along the width direction of the object to be measured due to periodic external force application to the object by the displacement detecting means. A displacement detection signal is generated, and the absolute value of each displacement detection signal is calculated by the first integral processing means every first period in which an external force is applied to the object to be measured and every second period in which no external force is applied to the object to be measured. The second integral processing means outputs each second integral amount of the noise component in each displacement detection signal for each of the first and second periods (both periods), and the applied external force is The calculation means calculates an external force to be applied to obtain a desired S/N ratio based on the S-ratio calculated from the first and second integral quantities, and the drive signal generation means generates a drive signal according to the calculation result. is generated to drive the external force applying means, and the difference means calculates the difference between the first and second integral amounts corresponding to each phase to obtain N differential signals, and the displacement correction means inputs and outputs the displacement detecting means. The N difference signals are corrected with a gain that linearly corrects the nonlinearity of the characteristics, and the measured object is measured at the displacement detection point of the object based on the corrected N difference signals and a preset calculation formula. The elongation rate representing the flatness of the body is calculated as the shape signal value by the elongation rate calculating means at predetermined intervals, and the timing generating means calculates the elongation rate of the first and second integral processing means and the difference means based on the reference signal of the drive signal. It is designed to control timing in operation.

[Effect]

In the shape detection device according to the present invention, the first integral amount output by the first integral processing means in each first period includes an integral amount due to a displacement signal component generated by applying a periodic external force and an irregularity of the object to be measured. The second integral processing means calculates the second integral amount of the noise component for each of at least one of the first and second periods, and the applied external force calculation means calculates the second integral amount of the noise component. An external force for obtaining a desired S/N ratio is calculated based on the S/N ratio obtained by assuming that the ratio of the first and second integral quantities obtained is approximately equal to the true S/N ratio, and the calculation result is calculated. The external force applying means applies an external force according to the drive signal to the object to be measured through the drive signal generating means, and the desired S
The difference means outputs N difference signals obtained from the difference between the first and second integral amounts corresponding to each phase obtained by the /N ratio twice per cycle, and the displacement correction means outputs N difference signals. The non-linearity of the input/output characteristics by the displacement detection means is corrected, and the elongation rate calculation means calculates the value at the displacement detection point of the measured object based on these corrected N difference signals and a preset calculation formula. The elongation rate indicating the flatness of the object to be measured is calculated and output at predetermined intervals.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, the same symbols as those in FIG. It is a bypass filter that allows the 22 has the same configuration as the integrator circuit 6, and is an integrator circuit after the bypass filter 21; 23 has the same configuration as the sample-and-hold circuit 7, and is a sample-and-hold circuit after the integrator circuit 22; 24 is the sample-and-hold circuit 7, 23; Integrating circuit 6 held at
, 22, which calculates the difference between the two integral results. Further, 25 is a sample and hold circuit having the same configuration as the sample and hold circuit 7, and holds the difference value taken by the subtractor 24, and 26 is a timing generation circuit, which is based on a reference signal from a rectangular wave generator 28, which will be described later. Polarity switch 5.
Integrating circuit 6゜22, sample hold circuit? , 23.2
A timing signal is generated for timing each operation of the subtractor 5 and the subtractor 24. Furthermore, 27 is
Manually re-output both sample and hold circuits 7.23 and S
28 is a rectangular wave generator as an example of a drive signal generator, which calculates the applied external force according to the amount of the disturbance signal. Depending on the calculation result of the calculation unit 27, a rectangular wave signal, for example, its level is changed and generated in the amplifier 3a. 29 inputs the difference value from the sample hold circuit 25 to the displacement converter 4;
A displacement corrector 30 corrects the non-linearity of C so that it becomes linear and outputs the result.
A displacement average value calculator 31 calculates the average value of displacement by inputting the corrected difference value from 9, and 31 calculates the elongation rate from the average value of displacement input from the displacement average value calculator 30 according to a preset calculation formula. This is an elongation rate calculator. Reference numeral 32 denotes a signal processing circuit made up of components shown by reference numerals 5 to 7 and 21 to 27, and 33 is an elongation rate signal processing circuit made up of constituent elements shown by numbers 29 to 31. Code 4C15
~7, 21 to 25, each part in double brackets is composed of a plurality of tubes (for example, N tubes), and for example, each of the displacement detection electrodes and displacement detectors 4b in the head 4 (for example, N tubes). )
If there are, they are arranged in series corresponding to them.

FIG. 2 is a diagram showing the signal waveforms of each part of the device shown in FIG. 1, with voltage values plotted on the vertical axis.
e) is the same as fat~(e) in FIG.

Figure 3 shows the relationship between the width of the strip 1 (position coordinate X) on the horizontal axis and the elongation rate β(x) when the vertical axis shows the tension T (x) per unit of the strip 1. FIG.

Next, the operation of this embodiment will be explained. During the period (taken), it is applied to the strip 1 as a rectangular wave of amplitude a.

Due to this external force f(t), the strip 1 is displaced, and the above (1
The amount of displacement shown in the first term of 12 is generated.

On the other hand, irregular vibrations are occurring in the strip l, which is the source of the disturbance signal as shown in (C) in Figure 2, and naturally the applied external force f
This irregular vibration d(t
) will be superimposed, and this noise component will be the above (11
It is expressed as the second term in Eq.

Displacement position P (x-t
) is converted into an electric signal by the displacement converter 4c via the displacement detector 4b, and the displacement detection signal shown in FIG. At step 7, the sample is released from the water position and returns to the position before displacement. completely opposite to the displacement direction of Tc l from nTc +□ (n+1
)Tc, the band l is displaced by the timing signal from the timing generation circuit 26, and the polarity of the displacement detection signal at the 0 point on the output side of the displacement converter 4C in FIG. 1 is integrated. Ru.

The waveform of the displacement detection signal inverted by the polarity switch 5 is +e) in FIG. 2 at the 0 point, which is the output side of the polarity switch 5.
It is indicated by. Further, the value integrated by the integrating circuit 6 is shown by (f) in FIG. At the time point (r++1)Tc, the output of the integrating circuit 6 is sampled and held by the sample and hold circuit 7.

By repeating the above operation, the output side of the integrating circuit 6 is 0.
As shown in FIG. 2(f), the signal at the point is 'Tc/2
For each time, the integral value of the displacement position P (x-t) of the above equation (11) is obtained, and the sample and hold circuit 7 receives the displacement amount P (of SL, N2, N3... x-t) is sampled and held.

On the other hand, the disturbance signal component at the 0 point due to the irregular vibration of the strip body 1 has a frequency sufficiently higher than the rectangular wave period Tc (as shown by C1 in FIG. 2), and the disturbance signal component due to the irregular vibration from nTc. A case where the quantities are approximately equal will be explained.

The disturbance signal component due to the irregular vibration of the band-shaped body 1 shown in FIG. 2(C) is input to a bypass filter 21 that passes only a frequency band sufficiently higher than the rectangular wave period Tc, and is extracted. The output of the bypass filter 21 is sent to the integrating circuit 22.
Only the disturbance signal due to the irregular vibration shown in FIG. 2(C) is integrated.

(n+1)Tc, and the integration circuit 2
The signal at point [F], which is the output side of 2, is as shown in FIG.

Then, the disturbance signal due to the integrated random vibration is (n+
1) At the time of Tc, the sample and hold circuit 23 samples and holds the data, and as shown in FIG.
2. For example, the integral value of the disturbance signal due to irregular vibration of N4 is (m-2) Tc, (m-1) Tc.

mTc, (m+1) can be obtained at the timing of Tc0.

Sample hold values Sl, S2 . which are integral values of displacement amounts already obtained. S3..., sample hold value No. which is the integral value of the disturbance signal due to irregular vibration, N2. N4・
. . , are sequentially determined by the subtractor 24 every Tc/2.

For the integral value S5, (m-1)Tc+□ to mTc
Integration of a disturbance signal due to irregular vibrations for a period of m
Integral value of displacement amount of Tc darkness from Tc + □ (m+1) S6
, the difference between N6 and the integral value N6 of the disturbance signal due to irregular vibrations during the same period is determined by the subtractor 24. Second
(f), (g), fh) in the figure show the waveforms of the above difference calculation, and the difference signal obtained by the difference device 24 is Tc/
[F
] The signal waveforms at points are CI, C2, C3 and (h) in Figure 2.
It is shown as...

Note that the timing generation circuit 26 determines the polarity switching timing of the polarity switch 5, the reset timing of the integrating circuits 6 and 22, and the sample hold circuit 7°23.25 based on the reference signal from the square wave oscillator 28. Control each timing such as timing.

The output expressed by equation (5) above is at point [F] in Figure 1 -
What is obtained for each Tc cycle is as described above.

That is, the above equation (5) is expressed as the following equation (7).

However, Kx: Coefficient in force balance at nTc/2 Now, to express the degree of shape defect (flatness) of the strip 1, consider the elongation rate β(x). The elongation rate β(x) is defined as the amount of elongation of the defective portion expressed as a ratio of the average portion of the defective shape to the length of the strip 1. The following (8
) holds true, and FIG. 3 illustrates it. If E is the elastic modulus of the strip 1, T(x)=-〒-±β(x) ・E ・・・・・・・・・
(8) Calculating β(x) from this results in the following equation (9).

-a From the above formula (7), T(x) = □ 2・Kz・C(x・-Tc) Similarly, the average tension T is obtained by the following αω formula.

Here, a plurality of cylinders (N pieces) of displacement measuring electrodes and N pieces corresponding to the displacement amount of the strip body 1 under average tension and arranged at appropriate intervals in the width direction of the strip body 1 are used. The average value of the N difference signals obtained by correcting the outputs of the N sample and hold circuits 25 obtained from the N displacement signals detected by the displacement detector 4b by the displacement corrector 29 according to the magnitude of the outputs. can be calculated by the displacement average value calculation unit 30.

By substituting T (x) and below into the above equation (9), the following α9 equation is obtained.

β(x) can be determined using the above equation 09.

In the above equation α9, and C(x) are calculated by detecting the displacement of the displacement detection electrode and the strip 1 shown in FIG. As already explained, it is generated by the displacement detection signal obtained by conversion. This displacement converter 4C
Generally, displacement and detection sensitivity are not linear.

As is clear from FIG. 4, which shows an example of its characteristics, the position when the strip 1 is not receiving external force f (t) is 10
1-, the output voltage of the displacement converter 4C is 50 mV when the strip 1 is displaced by 1fl from there, but when it is displaced by 3 cranes, it is not 150111V but 2oomv. Therefore, the output voltage of the displacement converter 4C is I
! 11 is not the same as the amount of displacement P (x-t). The above equation (5), that is, equation (7) assumes that the output of the displacement converter 4C is linear in the relationship between the amount of displacement and the output voltage. Therefore, equation (7) can be said to be a corrected difference signal.

However, as shown in FIG. 4, the displacement transducer 4C has non-linearity, so the elongation rate β calculated using the α0 formula above
(x) includes an error. A displacement corrector 29 is provided to correct this error. This displacement corrector 29 has a function of generating a gain that is varied depending on the magnitude of the output of the sample and hold circuit 25 and converting it into an accurate displacement amount. This variable gain is
The plurality of cylinders (N displacement transducers 4C) may each have different variable gain characteristics, or the N displacement transducers 4C may have different variable gain characteristics.
If the individual characteristic differences of C are within a permissible range, one type of variable gain characteristic may be provided.

Therefore, the gain is changed according to the magnitude of the output of the sample and hold circuit 25, the resulting difference signal is corrected by the displacement corrector 29, and the corrected difference signal is calculated by the manually operated displacement average value calculator 30. The elongation rate calculation unit 31 inputting the displacement average value and the corrected C (x) calculates the elongation rate β(x
) output can be obtained. In addition, L, a, E, Kt
is a value preset in the elongation rate calculator, which is detected by the electrode located at the X position of the strip 1 in the displacement measuring electrode, and is sent from the sample hold circuit 25 to the displacement corrector 29 and the displacement average value calculation. The difference signal C (
x) and the average difference signal, it becomes possible to calculate the above 0D formula. The elongation rate β(x) calculated by the elongation rate calculator 30 is displayed on the display device 11 via the display device control circuit 10, and is used for monitoring by the operator and as data for shape adjustment. . Furthermore, when automatically controlling the strip 1, the elongation rate β(x) is input to the roll crown adjustment device 13 via the roll crown control circuit 12 to achieve the purpose.

On the other hand, regarding the displacement detection signal at the point ■ in FIG. 1, referring to the above equation (1), by increasing the external force f(t), the first term becomes large and the S/N ratio can be increased. Therefore, if the irregular vibration d(t) of the strip 1 is large, the disturbance signal of (C1 in FIG. 2) also becomes large, and the integral value of the (force) in FIG. Then, increase the level of ('b) in Figure 2, and increase the level of ('b) in Figure 2.
The necessary S/N ratio can be secured by increasing the integral value of f).

A value obtained by holding the integral value of the disturbance signal due to irregular vibration is output from the sample-hold circuit 23, and the ratio of this integral value to the output of the sample-hold circuit 7, which is the integral value output of the displacement amount, is the S/N ratio. The applied external force calculator 27, which inputs these two signals from both sample and hold circuits 7 and 23, calculates the ratio of the re-input signals to output the current S/N ratio and calculate the required The external force f(t) necessary to ensure the S/N ratio is calculated and instructed to the rectangular wave generator 28.

Upon receiving this instruction, the rectangular wave generator 28 changes the rectangular wave signal, for example its level, and applies a required external force f (t) to the strip 1 via the amplifier 3a and the external force applying device 4a. In addition, the calculation for the external force applying device 4a can specifically calculate the current external force from the amount of displacement, and the calculated S
It can be calculated by functional calculation using the /N ratio and a desired S/N ratio set in advance, or it can be easily calculated by using a well-known interpolation formula.

The irregular vibrations of the strip 1 have stability over a relatively long period, and the tension T (x
) also does not fluctuate rapidly, so the external force ``(
The calculation period of t) does not need to be every rectangular wave period Tc;
The external force applying device 4a applies an external force f(
t) can be calculated.

Here, M may be set depending on the irregular vibration and tension state of the strip l.

In the above embodiment, the disturbance signal caused by the irregular vibration of the strip 1 is integrated only during the period when the external force f(t) is O. The disturbance signal due to irregular vibrations may be integrated in the same manner during the period of displacement, and the difference between the displacement amount and the integral value of the irregular vibrations during the same period may be determined.

Furthermore, it goes without saying that a plurality of electromagnets (for example, N pieces) of the external force calculator 27, the drive signal generator 28, the amplifier 3a, and the external force application device 4a may be provided.

〔Effect of the invention〕

As described above, according to the present invention, the amount of displacement is obtained by integrating and holding the displacement of the object to be measured by switching the polarity for each of the first period when an external force is applied and the second period when no external force is applied. , a disturbance signal due to irregular vibration of the object to be measured is passed through at least one of the first and second periods, and the amount of noise is obtained by integrating and holding, and the difference between the amount of displacement and the amount of noise is calculated. By performing the calculation, a displacement signal of the measured object from which irregular vibration noise of the measured object has been removed is obtained for each of the first and second periods, and further, the S/N ratio is calculated from the displacement amount and the noise amount. By doing this, the external force f(t) should be always maintained to ensure the expected S/N ratio. By correcting the difference value, the displacement of the measured object and the nonlinearity of the displacement conversion voltage output are corrected, and the elongation rate is calculated using the average value of the corrected difference values, the corrected difference value, and the set value. Therefore, the shape of the object to be measured is different between the first period and the second period.
It is possible to detect the shape of the object with a high response speed by periodically obtaining it every period of time, and it is possible to detect the shape of the object with high precision by adjusting the external force. This method has the effect of being able to quantitatively grasp the degree of physical shape defect, and further, obtaining an accurate amount of displacement and highly accurate elongation of the object to be measured.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing a shape detection device according to an embodiment of the present invention, Fig. 2 is a signal waveform diagram of signal processing of each part of the device shown in Fig. 1, and Fig. 3 shows the relationship between tension distribution and elongation rate. 4 is a diagram showing the characteristics of the displacement transducer, FIG. 5 is a block diagram showing a conventional shape detection device, and FIG. 6 is a signal waveform diagram of signal processing of the conventional device. In the figure, 1 is a strip-shaped body, 4a is an external force applying device, 4b is a displacement detector, 4c is a displacement converter, 5 is a scratchiness switch, 6.
22 is an integral circuit, ? , 23.25 is a sample hold circuit, 21 is a bypass filter, 24 is a difference device, 26 is a timing generation port 4.27 is an applied external force calculator, 28 is a drive signal generator, 29 is a displacement corrector, 30 is a displacement average A value calculator, 31 is an elongation rate calculator. In addition, in the figures, the same reference numerals indicate the same or corresponding parts. Figure 2-〇=b knee N4

Claims (2)

[Claims] (1) A drive signal in which one period consists of a first period and a second period is input, and tension is applied to the object to be measured in a direction crossing the width direction of the surface of the object to be measured along the width direction. Said first
an external force applying means that applies an external force every period of time; and a displacement detecting means that detects displacements at N locations along the width direction of the object to be measured due to the application of the external force and generates N displacement detection signals. and outputs a shape signal indicating the shape of the object to be measured based on the displacement detection signal, each of the first period and the second period in which the external force is not applied to the object to be measured. a first integral processing means that calculates a first integral amount of the absolute value of each of the displacement detection signals at each time; second integral processing means for calculating second integral amounts of each noise component due to irregular vibrations of the object to be measured;
applied external force calculating means for calculating an S/N ratio from the first and second integral quantities, and calculating an external force to be generated by the external force applying means in order to obtain a desired S/N ratio based on the S/N ratio; and a drive signal generating means for generating the drive signal according to the calculation result of the applied external force calculation means, and obtaining N difference signals by calculating the difference between the first and second integral quantities corresponding to each phase. a difference means, a displacement correction means for correcting the difference signal with a gain corresponding to the nonlinearity that corrects the nonlinearity of the input/output characteristic in the displacement detection means so as to make it linear; elongation rate calculation means for calculating an elongation rate representing the flatness of the measured object at a displacement detection location of the measured object as a value of the shape signal based on the N corrected difference signals and a preset calculation formula; and a timing generation means for controlling operational timing of the first and second integral processing means and the difference means based on a reference signal of the drive signal. (2) The N corrected difference signals are C(x_1),
C(x_2),...C(x_N), the position coordinate in the width direction of the object to be measured is x, and among the N corrected difference signals at the x position of the x coordinate, Let C(x) be the corrected difference signal corresponding to C(x), let L be the value corresponding to the span applying the tension to the object to be measured, and let The value corresponding to the amplitude of the corresponding object to be measured is a, the value corresponding to the coefficient in force balance is K, the value corresponding to the elastic modulus of the object to be measured is E, and the elongation rate is β ( x
), the above calculation formula is β(x)=(L・a)/(2・K・E)(1/@C@−
1/[C(x)]) However, @C@=1/N[C(x_1
)+C(x_2)+...+C(x_N)] The shape detecting device according to claim 1.