JPH07137062A - Method of measuring amount of calaneder bank - Google Patents

Abstract

PURPOSE:To enable execution of an operation with a bank control value determined easily for each sort and to always enable execution of accurate measurement by a method wherein a brightness difference of a picked-up image plane is enlarged by an AGC processing, an offset for electric noise is removed, an image is binary-coded and a bank image is cut out. CONSTITUTION:In a method wherein the image of a bank 3 between calender rolls 1 and 2 is picked up by an infrared camera 4 and subjected to an image processing and the amount of the bank is measured therefrom, first a brightness difference of a picked-up image plane is enlarged by an automatic gain control(AGC) processing. Then, a window 31 containing the bank 3 and the peripheral part thereof is set in the image lane subjected to the AGC processing, and an emphasizing image processing wherein the minimum density in the image plane is made a set minimum density gradation and the maximum density therein a set maximum density gradation is executed. Moreover, an offset left for electric noise is removed, a change is made so that the minimum and maximum densities in the image plane after the removal be made the set minimum and maximum density gradations respectively, binary-coding is executed at a fixed binary-coding level set beforehand, and a bank image 30 is cut out.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention controls a bank amount, which is one of important control items that affect variations in the thickness of a sheet when calendaring various plastics or rubbers to produce a sheet. The bank amount,
In particular, the present invention relates to a method of measuring the amount of the first bank, which eliminates a measurement error caused by a change in bank temperature.

[0002]

2. Description of the Related Art Heretofore, as a method of controlling a bank amount, a bank amount formed between calender rolls is measured, and based on the measurement result, a raw material feed conveyor which oscillates in the axial direction of the rolls is used. A method of controlling the material supply amount is known, and a method of capturing a bank image with an infrared camera is known as a method of measuring the bank amount.

That is, as shown in the sectional view of FIG.
When the resin bank 3 formed between the roll 1 and the second roll 2 is photographed by the infrared camera 4, the bank portion (resin portion) has a high emissivity and the other peripheral portions (roll surface and the like).
Since the emissivity is low, the temperature of the bank is high (bright on the screen) and the temperature of the roll is low (screen You can get a screen that appears dark. 2 in FIG.
0 is the image of the bank.

The density curve on AA 'of this screen generally has a shape as shown in FIG. 4, which is binarized by an appropriate grayscale gradation value (binarization level) L to obtain the density L. The size of the bank is determined by measuring the area (number of pixels) of the portion determined to be above. The gray value is usually
It is divided into 0 (black) to 255 gradations (white). Then, the bank amount is controlled by controlling the raw material supply amount from the raw material feed conveyor 7 shown in FIG.

[0005]

However, in general, when the material composition is different, the optimum bank temperature for calendar forming is different, so that the set temperatures of the rolls 1 and 2 are changed for each composition. Even if the composition is the same, the temperature of the bank varies depending on the size of the bank, the gap between the rolls and the like.
For these reasons, the bank temperature actually changes at a level of about ± 10 ° C.

On the other hand, the relationship between the temperature of the object and its image density in the infrared camera can be set as appropriate. For example, in the case of polyvinyl chloride resin, the suitable range is 0 (black) as shown in FIG. Assuming that the temperature is A and the temperature at which the density is 255 (white) is A + B, it is appropriate that A is 90 to 120 ° C. and B is 50 to 80 ° C. For example, A = 100.
℃, B = 50 ℃, ± 10 ℃ temperature change is ± 20%
Changes in the density value of. Therefore, when the bank temperature fluctuates, as shown in FIG. 4, the concentration curve changes like a curve 10 when the temperature is high and a curve 20 when the bank temperature is low. The bank size cannot be measured correctly when it is fixed.

As a countermeasure against such a variation in the density (brightness) of the screen, P which automatically determines the binarization level is set.
There is an image processing technique such as the -tail method, or an AGC (Automatic Gain Control) processing technique that automatically adjusts the video signal waveform in an analog manner before performing the image processing to make the screen easy to see. As described above, since the density change is as large as about ± 20%, the measurement error of the bank size due to the temperature change cannot be eliminated.

[0008]

SUMMARY OF THE INVENTION The present invention combines analog image processing technology and image processing technology for video signals to bring the density of the bank portion to a maximum (white) and the density of the roll surface to a minimum (black). Magnified in real time, this image shows 2
By measuring the size of the bank with the value level fixed, the measurement error of the size of the bank due to the temperature change is eliminated.

That is, the present invention relates to a method of measuring a bank amount by photographing a bank formed between calender rolls with an infrared camera and subjecting the obtained image to image processing. 1) AGC (Automatic Gain Control) processing 2) Set the window including the bank and its surroundings in the AGC-processed screen, and set the minimum density of the screen in the window to the minimum density gradation and the maximum density. Enhance image processing to set maximum density gradation. 3) Furthermore, except offsets left behind due to electrical noise, 4) Regarding the screen after offset removal, the minimum density of the screen becomes the set minimum density gradation. Convert the maximum density to the set maximum density gradation, and 5) binarize the image at a preset fixed binarization level and cut out the bank image. It is a method of measuring the calendar bank the amount of the butterflies.

The present invention will be described in detail below with reference to the drawings. 1 is a cross-sectional view of an example of an apparatus used for carrying out the method of the present invention, FIG. 2 is a screen shot by an infrared camera, FIG. 3 is a diagram for explaining the processing procedure of the present invention, and FIG. 4 is A-A of FIG. ´
The above density curve, FIG. 5 is a diagram for explaining the relationship between the object temperature and its image density in the infrared camera.

In FIG. 1, the raw material resin from the heating roll 5 becomes a belt-shaped resin 6 and is supplied to a calendar roll by a raw material feed conveyor 7 to form a bank 3. The raw material feed conveyor 7 oscillates in the roll axis direction by swinging around the fulcrum.

When the bank 3 is photographed by the infrared camera 4, a bank image 30 as shown in FIG. 2 is obtained. FIG. 3A shows a change in voltage (video signal) representing a difference in brightness between line segments AA ′ on the bank image 30.
FIG. 3A also shows electric noise 32 that cannot be avoided when handling an image.

When AGC (automatic gain control) processing is performed to automatically adjust the size of the video signal so that the entire screen is easy to see, the waveform becomes 0 V in the low part of the video signal as shown in FIG. 3B. As a result of the high portion being brought close to the set maximum voltage (1V), the difference in brightness becomes large.

However, since this AGC processing has a function of automatically adjusting the overall brightness by the analog voltage level when the lightness and darkness of the original image fluctuates as a whole, the bank unit 3 and the background of FIG. As described above, it is often the case that the difference between the light and dark areas is insufficiently expanded. Therefore, in the present invention, the following enhancement processing is performed by an image processing technique that converts a video signal into a density gradation that is a discrete numerical value that represents light and shade and performs various processing.

That is, first, the screen is divided into a large number of cells, and the brightness of each cell is digitized as a density gradation value. The density gradation is usually set separately from 0 (black) to 255 (white) gradation. Then, a window 31 having the bank and its periphery inside is created at an appropriate position, and the minimum density gradation of the screen in the window is set to the minimum density gradation (0 gradation).
To increase the maximum density gradation in the window to the set maximum density gradation (usually 255 gradations) to emphasize the entire screen. The waveform obtained as a result is illustrated in FIG.

At this time, due to the electrical noise 32, the gradation value of the noise 32, which is smaller than the gradation in the peripheral area of the bank, becomes the minimum density gradation in the window 31, so that the peripheral area of the bank is 0.
Only the gradation value larger than the gradation is converted, and the peripheral portion of the bank also has a considerable brightness, so that the entire image becomes a bright image.

Therefore, when the image once converted into the density gradation value for the emphasis processing is returned to the video signal again, the offset amount due to noise (the video signal value C corresponding to the gradation value C '
Except for (V)), C (V) has 0 gradation and 1 (V) has 255 gradations.
The density value is converted again so as to obtain gradation.

The enlarged image of the bank portion as shown in FIG. 3 (d) obtained as a result is fixed because the bank portion has 255 gradations and the peripheral portion has 0 gradations by the above series of processing. The bank size can be measured by binarizing the bank portion using the binarized level L.

According to the method of the present invention, as described above, even if the bank temperature changes, the density gradation difference between the bank portion and the peripheral portion can always be maximized. The bank part can be binarized by using this.

[0020]

According to the method of the present invention, even if the material composition is changed, the amount of calendar bank can be measured without changing the temperature range of the infrared camera or the binarization level for cutting out the bank each time. It is possible to easily determine the bank amount management value for each operation.

Further, even if the same type of product is used, the bank temperature fluctuates during operation. Against this, there is no need to change the temperature range or the binarization level of the infrared camera, and accurate measurement can always be performed. it can.

[Brief description of drawings]

FIG. 1 is a sectional view of an example of an apparatus used for carrying out the method of the present invention.

FIG. 2 is a diagram showing a shooting screen of an infrared camera.

FIG. 3 is a diagram illustrating a processing procedure of the present invention.

FIG. 4 is a diagram showing a concentration curve on AA ′ in FIG.

FIG. 5 is a diagram illustrating a relationship between an object temperature and an image density of the infrared camera.

[Explanation of symbols]

 3 bank 30 bank image 31 window 32 electrical noise 4 infrared camera 7 raw material feed conveyor

Claims (1)

[Claims] 1. A method for measuring a bank amount by image-processing an obtained image of a bank formed between calender rolls with an infrared camera, and 1) a photographing screen by AGC (automatic gain control) processing. 2) Set the window including the bank and its surroundings in the AGC-processed screen, set the minimum density of the screen in the window to the minimum density gradation, and set the maximum density to the maximum density. 3) Furthermore, the enhanced image processing for gradation is performed. 3) Furthermore, the offset left behind due to electrical noise is removed. 4) The screen after the offset is removed, the minimum density of the screen is the set minimum density gradation and the maximum density is A calendar characterized by converting to a set maximum density gradation, and 5) binarizing an image at a preset fixed binarization level to cut out a bank image. Link the amount of the measurement method.