JP2002236004A - Method and apparatus for measuring thickness of light transmission body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and apparatus capable of measuring the thickness of a light transmission body by which the thickness of a light transmission body, such as a piece of paper 1, etc., can be measured accurately, and accordingly, the reliability of the measurement can be improved. SOLUTION: In the method, the light transmission body, for example, a piece of paper 1 is successively transmissively illuminated over the full length of the paper 1 in the width direction by means of a lighting means 2, while the paper 1 is made to rum. The image of the transmissively illuminated portion of the paper 1 is picked up by means of black-and-while CCD line sensor cameras 6a-6d. The concentration level data, which averages the concentration levels for every region of almost all the areas of the paper 1 are found, based on multi-level line data successively outputted from the sensors 6a-6d by means of a region concentration averaging section 8. An inspection data processing section 11 compares the averaged concentration level data which are found with reference concentration level data and measures the thickness of the paper 1 from the compared results.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to various film-forms such as papermaking or sheet-like paper, non-woven fabric, film-form, and the like.
Alternatively, the present invention relates to a method and apparatus for measuring the thickness of a light-transmitting material used for measuring the thickness of various light-transmitting materials, such as sheet-like plastic, and detecting the presence or absence of quality defects due to the thickness of the light-transmitting material. .

[0002]

2. Description of the Related Art For example, in the case of papermaking, it is necessary to make the whole paper to have a substantially uniform thickness in order to achieve the standard. Further, even in a separator made of non-woven fabric used for a mobile phone, if there is a thin portion, short-circuiting occurs, so that it is necessary to form the whole as a substantially uniform thickness.

Conventionally, in order to measure the thickness of a light-transmitting body as an object to be inspected as described above, β is measured on both sides of the running light-transmitting body.
The line emitter and the detector are moved (scanned) in the width direction of the translucent body, during which the β-ray is emitted from the β-ray emitter, and the amount of β-ray transmitted through the translucent body is detected by the detector. . Then, the thickness of the light transmitting body is measured by comparing the transmission amount of the β-ray with the reference transmission amount.

[0004]

However, in the conventional thickness measuring method as described above, the thickness of the light transmitting body is measured by moving the β-ray emitter and the detector in the width direction of the running light transmitting body. Therefore, only the meandering surface of the desired width in the light transmitting body can be measured in thickness, and the thickness of the entire surface cannot be measured. Therefore, accurate thickness measurement cannot be expected and reliability is poor. In addition, the handling of β-rays is dangerous, and it is not practical because of the restrictions on the inspector, such as the inspector having a qualification in the handling.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-described problems of the conventional example, and it is possible to accurately measure the thickness of a light transmitting body, and thus to improve the reliability of the measurement. It is an object of the present invention to provide a method and a device for measuring the thickness of a light-transmitting member which can be used.

[0006]

In order to achieve the above object, a method for measuring the thickness of a light transmitting body according to the present invention includes illuminating a light transmitting body, detecting a density level of the light transmitting body by light transmission, and detecting a density level of the light transmitting body. Based on the detected data, density level data for averaging almost the entire density level in each predetermined region of the light transmitting body is obtained, and the thickness of the light transmitting body is measured from the detected density level data. Things.

According to another aspect of the present invention, there is provided a method for measuring a thickness of a light-transmitting member, comprising the steps of: comparing detected density level data for each predetermined area of the light transmitting member with reference density level data; The presence or absence of a thickness defect in the light transmitting body is determined based on whether the difference is within a range of an allowable value.

In each of the thickness measuring methods, the detected density level data for each predetermined region of the light transmitting body can be obtained from the multi-gradation line data sequentially output.

In order to achieve the above object, a light-transmitting member thickness measuring apparatus according to the present invention comprises:
Detecting means for detecting a density level due to light transmission of the light-transmitting member; and a density level for averaging substantially the entire density level in each predetermined region of the light-transmitting member based on detection data output from the detecting means. Means for obtaining data and measuring the thickness of the light transmitting body from the detected density level data.

In order to achieve the above object, another thickness measuring apparatus according to the present invention, in the thickness measuring apparatus, compares detected density level data for each predetermined region of the transparent body with reference density level data, It is provided with a judging means for judging a thickness defect of the light transmitting body based on whether or not the difference is within a range of an allowable value.

According to another aspect of the present invention, there is provided a thickness measuring apparatus according to the present invention, wherein each of the thickness measuring apparatuses detects the light from the illuminating means leaking from both sides of the light-transmitting member, detected by the detecting means. Control means for comparing the illuminance of light with a reference illuminance and performing feedback control of the illumination means so that the illuminance of the illumination light from the illumination means is substantially constant.

In each of the thickness measuring devices, the illuminating means includes a light source for emitting illumination light, a light-transmitting container for receiving the illumination light emitted from the light source, and a temperature in the light-transmitting container. And a temperature adjusting means for adjusting the light amount of the light source to be substantially constant. Further, a monochrome line sensor camera can be used as the detection means.

According to the present invention configured as described above,
A density level due to light transmission over substantially the entire surface of the light-transmitting body is detected, and density level data for averaging almost the entire density level in each predetermined area of the light-transmitting body is obtained based on the detected data. Since the thickness of the light transmitting body is measured from the level data, the entire thickness of the light transmitting body can be accurately measured.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic configuration diagram showing a thickness measuring device applied to paper as a light transmitting body as one embodiment of the present invention, FIG. 2 is an explanatory diagram showing an example of a paper measurement area for measuring thickness according to this embodiment, FIG. 3 is an explanatory diagram showing multi-gradation line image data on the line ww in FIG. 2 on paper for measuring the thickness according to the present embodiment, FIG. 4 is a principle explanatory diagram for measuring the thickness of the paper according to the present embodiment, FIG. 5 is an explanatory diagram showing an average density level of a measurement area according to the present embodiment of the paper whose thickness is to be measured, and FIG. 6 is a graph showing a relationship between the paper thickness and the light transmittance.

As shown in FIG. 1, a traveling device (not shown)
Illumination means 2 is provided below the band-shaped paper 1 which is the measurement target running in such a manner as to cross in the width direction of the paper 1. In the illumination means 2, a light source 3 capable of emitting visible light, infrared light, or the like as illumination light, such as a fluorescent lamp, a metal halide lamp, a halogen lamp, a mercury lamp, or an infrared lamp, is housed in a light transmitting container 4. . The light source 3 is adapted to adjust the amount of light emitted by the illumination power supply unit 5. The light source 3, especially the fluorescent lamp, has an ambient temperature of about 25 to 28 ° C.
Since the temperature near the peak, the temperature will drop if the ambient temperature is too low or too high, it is not affected by the ambient temperature as much as possible,
The temperature in the light transmitting container 4 can be adjusted by a temperature adjusting means (not shown) by utilizing the Peltier effect, circulating a cooling medium, or the like so that the amount of emitted light can be kept substantially constant. . By irradiating the lower surface of the paper 1 with the illumination light emitted from the illumination means 2, the illumination light can be transmitted through the paper 1. The illuminating means 2 is set so as to emit the illuminating light with a wider width than the paper 1 and to leak the illuminating light upward from both sides of the paper 1, thereby confirming the brightness of the illuminating light emitted from the illuminating means 2. Can be.

Black-and-white CCD line sensor cameras 6a to 6d, which are means for detecting a density level (amount of transmitted light) due to light transmission, are arranged above the running strip-shaped paper 1 so as to face the illuminating means 2. Have been. CCD line sensor cameras 6a-6d are 512, 1024, 204
This is a linear sensor of 8, 5000 bits or the like, and one or more (four in the illustrated example) are arranged along the width direction of the traveling paper 1 and transmitted by the illumination light on the traveling paper 1. The illuminated portion can be sequentially imaged over the entire width. Further, the CCD line sensor cameras 6a to 6d arranged on both sides can detect illumination light leaking upward from both sides of the paper 1.

The image input unit 7 can sequentially take in 256-level multi-gradation line image data captured by the CCD line sensor cameras 6a to 6d. The area density averaging unit 8 performs multi-level density processing for each predetermined area in the width direction and the running direction of the paper 1 captured by the CCD line sensor cameras 6a to 6d from the multi-level line image data captured by the image input unit 7. The levels are digitized, averaged and stored in memory. The defect detection processing unit 9 captures images with the CCD line sensor cameras 6a to 6d, digitizes the multi-gradation line image data captured by the image input unit 7, stores the data in a memory, and stores the data in the width direction and the running direction of the paper 1. Multi-tone area (area) image data is created for each predetermined area and stored in a memory. The area where the data is created by the defect detection processing unit 9 may be the same as the area where the data is created by the area density averaging processing unit 8, or may be different. Then, the density level of each pixel portion of the multi-tone area image data is set to 256 as a reference stored in the memory in advance.
The density levels of the corresponding pixel portions of the multi-level gradation image data are compared with each other, and the density level difference between the corresponding portions of the two image data is determined based on the allowable value. The defect location of the defect can be determined.

The illuminating light reference density management unit 10 controls the CCs on both sides.
From the multi-gradation line image data detected by the D line sensor cameras 6a and 6d and captured by the image input unit 7, the brightness of the illumination light leaking upward on both sides of the paper 1, that is, the illuminance, is obtained. Is set in advance and compared with a reference illuminance stored in a memory. If the illuminance deviates from the allowable value, the illumination power supply unit 5 is fed back so that the illuminance of the illumination light emitted from the light source 3 of the illumination means 2 becomes substantially constant. Control.

The inspection data processing section 11 converts the 256-step multi-gradation detected density level data averaged by the area density averaging section 8 into 256 levels of light transmission which are preset and stored in a memory. And the thickness of the paper 1 can be measured based on the comparison result of the density level (the amount of transmitted light). In the present embodiment, the inspection data processing unit 11 includes the area density average processing unit 8
The multi-gradation detected density level data averaged in the above is compared with the reference density level data, and from this comparison result, the thickness defect in the paper 1 can be determined based on the allowable value. The judgment data can be stored in the memory. In addition, the inspection data processing unit 11 can store data on the presence or absence of a light defect and a dark defect of the paper 1 determined by the defect detection processing unit 9 in the memory. Then, the inspection data processing unit 11
Can be displayed on a display unit 12 made of a CRT or the like, and the data can be displayed on the display unit 12 made of a CRT or the like. Each can be output.

The rotary encoder 13 generates a timing pulse every time the paper 1 travels a predetermined length in order to detect the travel amount of the paper 1. The external interface 14 controls the image input unit 7, the area density average processing unit 8, and the defect detection processing unit 9 by inputting a timing pulse from the rotary encoder 13, and controls the image input unit 7 from the CCD line sensor cameras 6 a to 6 d. An instantaneous image of the imaging range is captured, and the area density average processing unit 8
, The density level is averaged for each area designated by the timing pulse by the rotary encoder 13, and the defect detection processing section 9 uses the timing pulse from the image input section 7 as a line feed signal from the image of the image input section 7 as a multi-tone area image. Data is created, and the presence or absence of a defect is determined.

The above configuration will be described in further detail below together with its operation. Since the relationship between the paper thickness and the light transmittance varies depending on the type of paper, such as the material of the paper, the papermaking method, etc., for each paper for which the thickness is to be measured, as shown in FIG.
Calibration curve (calibr) showing the relationship between paper thickness and light transmittance
is calculated, and the correspondence data between the paper thickness and the reference level of the light transmission amount (density), for example, the density level value and the paper thickness are arranged so as to correspond to each other and stored in the memory of the inspection data processing unit 11. Keep it.

Then, as shown in FIG. 1, the paper 1 whose thickness is to be measured is run, the paper 1 is sequentially transmitted and illuminated from the lower side by the illumination light emitted from the illuminating means 2, and the width of the paper 1 is increased from the upper side. Images are sequentially taken along the running direction by the monochrome CCD line sensor cameras 6a to 6d over the entire length in the direction. At the time of this imaging, a timing pulse is input from the rotary encoder 13 to the external interface 14 every time the paper 1 travels for a predetermined length.
The image input unit 7 sequentially captures 256-step multi-gradation line image data picked up by the CCD line sensor cameras 6a to 6d in accordance with the signal from the multi-level input unit 4, and the multi-gradation acquired by the area density averaging unit 8 into the image input unit 7 The multi-gradation density level is specified for each area of the width and the desired length specified by the timing pulse by the rotary encoder 13 from the line image data and imaged by the CCD line sensor cameras 6a to 6d.

When the inspected surface of the paper 1 illuminated by the illumination means 2 is imaged by the CCD line sensor cameras 6a to 6d, the CCD line sensor cameras 6a to 6d
Is determined by the amount of illuminating light transmitted through the paper 1, the output signal has a low level in a thick portion of the paper 1, has a high level in a thin portion of the paper 1, and causes a density difference due to the thickness of the paper 1. , Appear as a change in the pulse shape at a level corresponding to the shading. Thus, by averaging the desired area of the paper 1 by the area density averaging processing unit 8 as described above, the tendency of shading (paper thickness) of the entire paper due to the basis weight at the time of papermaking of the paper 1 is obtained. be able to. Then, the area density average processing section 8 digitizes the averaged test density level data and stores it in a memory, and the test data processing section 11 stores the averaged test density level data in a memory in advance. The thickness of each area of the paper 1 corresponding to the density is measured based on the result of comparison with 256-level multi-gradation density level data serving as a digitized reference of a certain paper 1, and further, the presence or absence of a defect is determined. Then, these data are stored in the memory. Note that the reference density level data can be created from the inspected inspection surface of the running paper 1 or can be created in advance based on a papermaking sample,
It can also be created in advance from other known data.

The defect detection processing section 9 digitizes the 256-level multi-gradation line image data sequentially taken into the image input section 7 and stores it in a memory. A multi-gradation area (area) image data is created using a pulse as a line feed signal. The density level of each pixel portion of the multi-tone area image data is digitized in advance in a memory and stored as a reference. Then, the presence or absence of a defect is determined based on a preset allowable value of the density level difference between the corresponding portions of the two images, and this determination data is stored in the memory. The reference area image data can be created in the same manner as described above.

The display unit 12 displays the measurement data of the paper thickness measured by the inspection data processing unit 11, the determination data on the presence or absence of the quality defect, and the data on the presence or absence of the quality defect determined by the defect detection processing unit 9. . Thereby, the inspector can confirm the data of the paper thickness and the determination result regarding the presence or absence of the quality defect. The inspection data processing unit 1
1 can output measurement data and judgment data, and further can issue an alarm so that the inspector can confirm the presence or absence of a quality defect by hearing, or visually.

An example of the measurement principle will be described more specifically. The measurement area for averaging the density level of the paper 1 in the area density averaging unit 8 is measured in a large area when the paper 1 is cut into a large area and used, and the paper 1 is cut into a small area. When the paper 1 is used, the measurement is preferably performed in a small area, that is, the paper 1 is preferably cut and measured in an area corresponding to the size to be used.
Now, assuming that the width of the paper 1 is 1 m, each of the CCD line sensor cameras 6a, 6b, 6c, and 6d has a resolution of 0.25 mm × 4096 bits. As shown in FIG. Each CCD line sensor camera 6a, 6b,
Areas a1, a2, a3, a where the width x of the paper 1 is 250 mm and the length y in the running direction of the paper 1 is 250 mm for each of 6c and 6d.
4, a5, ..., b1, b2, b3, b4, b5, ..., c
1, c2, c3, c4, c5, ..., d1, d2, d3,
It is assumed that the density levels are averaged at d4, d5,.

Now, the regions a1 to d1 in FIG.
It is assumed that the multi-gradation line image signal of the ww line is as shown in FIG. The area density averaging unit 8 converts the multi-tone line image signal as described above into digital data, sequentially adds the digital data, and divides by the number of pixels to obtain averaged detected density level data. Here, as shown in FIG. 3, the paper 1 has bright defects 15 and 16 such as pinholes and dark defects 17 and 18 due to foreign matter and the like (in FIG. 3, for convenience of explanation, w Bright defects 15, 16, on the -w line
Although the dark defects 17 and 18 are shown as being present, such defects are not concentrated on each line. ). However, as described above, the width x is 250 m
m, the number of pixels in an area a1 or the like having a length y in the traveling direction of 250 mm is such that the resolution of x and y is 0.25.
In the case of mm / pixel, the number is about one million pixels. In the averaging process of such a large number of pixels, the bright defects 15, 16 and the dark defects 17, 18 are temporarily provided in a plurality of places in each area a1 and the like. Even if present, there is no risk of affecting the averaging process.

It is assumed that, as a result of the averaging process by the area density averaging section 8, the average density levels of the areas a1 to a5 picked up by the CCD line sensor camera 6a are as shown in FIG. In the inspection data processing unit 11, the areas a1 to
The averaged density level data a5 and the reference density level data A are compared, and the areas a1 to a1 of the paper 1 are referred to with reference to a table in which the reference density level values and the sheet thickness are arranged in correspondence.
The thickness at 5 is measured. Now, assuming that India paper is used as paper 1, in this India paper 1,
Since the reference paper thickness is around 0.040 mm, the calibration curve of the thickness and the light transmittance is as shown in FIG. In the illustrated example, in the area a1, the level value of the average density level data is “200”, which is the same as the level value “200” of the reference density level data A.
It is determined that the thickness is 0.040 mm. In the area a2, the level value of the average density level data is “20”.
5 ”and the level value“ 20 ”of the reference density level data A.
Since “0” is the “+5” level, the thickness is 0.0
It is determined to be 36 mm. In the areas a3 and a4, the level value of the average density level data is “210”.
And the level value “200” of the reference density level data A.
Is “+10” level, the thickness is 0.03
It is determined to be 2 mm. In the area a5, since the level value of the average density level data is “195”, which is “−5” level with respect to the level value “200” of the reference density level data A, the thickness is 0.044 mm. Is determined.

In this way, the thickness of the entire India paper 1 can be measured. By the way, the thickness of the paper 1 is determined by the basis weight (g / 1 m ² ) at the time of papermaking, and the basis weight is determined in the areas a1, a2, a3, a4, a
5, ... does not vary greatly, and in general,
It will vary depending on the length of tens or hundreds of meters,
The variation in FIG. 4 is merely an example for assisting understanding of the measurement principle. In practice, one example is CC
Areas a1, a imaged by D line sensor camera 6a
It is assumed that the average density level data Y of 2, a3, a4, a5,... Becomes as shown in FIG. 5 between about 5000 m from the measurement start end.

Range Y from the measurement start end to around 125 m
In the case of 1, the average density level is about "195" to "200".
Between about 0.044 mm to 0.040
It is measured in the range of mm. In the range Y2 of about 125 m to about 540 m, the average density level is about “200” to “20”.
4 ", the thickness is about 0.040 mm to 0.040 mm.
It is measured in a range of 352 mm. About 540m to about 175
In the range Y3 of 0 m, the average density level is about “190”.
~ "200", so the thickness is about 0.048mm
It is measured in the range of ０．０0.040 mm. About 1750m ~
In the range Y4 of about 2165 m, since the average density level is between about “200” to “202”, the thickness is about 0.2 mm.
It is measured in the range of 040 mm to 0.038 mm. About 2
In the range Y5 from 165 m to about 2750 m, since the average density level is between about “195” to “200”, the thickness is measured in the range from about 0.044 mm to 0.040 mm. In the range Y6 of about 2750 m to about 3460 m, since the average density level is between about “200” to “211”, the thickness is measured in the range of about 0.040 mm to 0.0332 mm. Range Y7 of about 3460 m to about 3670 m
Since the average density level is between about “190” and “200”, the thickness is about 0.048 mm to 0.040 m.
It is measured in the range of m. In the range Y8 of about 3670 m to about 4250 m, the average density level is about “180” to “1”.
90 ", so that the thickness is about 0.056 mm to 0.1 mm.
It is measured in the range of 048 mm. About 4250m to about 50
In the range Y9 of 00 m, the average density level is about “19”.
0 ”to“ 200 ”, the thickness is about 0.048.
It is measured in the range of mm to 0.040 mm.

When measuring the thickness of the paper, India paper 1
Is added to the standard thickness of the India paper 1 on the thinner side and the thicker side which does not cause a problem in use, that is, a certain allowable value which does not cause a problem in use is added to the reference density level A. A permissible density level C on the “dark” side obtained by subtracting a predetermined permissible value from the permissible density level B on the “bright” side and the reference density level A obtained as a result is set.

Now, the tolerance on the side thinner than the reference thickness of the India paper 1 is 0.032 mm, that is,
The value of the permissible density level B on the “bright” side is set to “210”, and the permissible value on the side thicker than the reference thickness of the Indian paper 1 is 0.048 mm, that is, the permissible density on the “dark” side. It is assumed that the value of level C is set to “190”. As a result, the inspection data processing unit 11 sets the measurement ranges Y1 to Y
At 5, Y7 and Y9, the averaged density level is higher on the “dark” side or “bright” side with respect to the reference density level A, but within the allowable density levels B to C, It is determined that the paper is normal because the paper becomes thicker or thinner within an allowable value with respect to the reference paper thickness. In the measurement range Y6, the averaged density level is lower on the “bright” side than the reference density level A, and the range of Y6a is outside the range of the allowable density level B on the “bright” side. Therefore, it is determined to be a defect, and the other portions are within the range of the allowable density level B, and are only thin within the allowable value with respect to the reference paper thickness. I do. In the measurement range Y8, the averaged density level is lower on the “dark” side with respect to the reference density level A, and is outside the range of the allowable density level C. It is determined that it is a defect because it has become thicker.

As described above, the paper 1 has a basis weight (g / 1 m ² )
Since the thickness is determined by the above, the paper thickness is measured as described above, and further, the presence or absence of a defect is determined, whereby the basis weight of the paper 1 to be inspected can be obtained. Feedback can be provided to control the basis weight.

An example of the defect detection principle will be described more specifically. Now, as described above, the multi-gradation line image on the ww line of the paper 1 shown in FIG. 2 is provided in the form of a signal waveform having 256 multi-gradation density levels as shown in FIG. The signal waveform is stored in the memory of the defect detection processing unit 9 as 256-level gradation data. When the inspection surface of the paper 1 transmitted and illuminated by the illuminating means 2 is imaged by the CCD line sensor cameras 6a to 6d, the output signals from the CCD line sensor cameras 6a to 6d are defined by the transmission amount of the illumination light as described above. As a result, high levels of bright defects 15, 16 such as pinholes occur,
The level is low at the dark defects 17 and 18 such as foreign matter adhesion.

In order to detect a deformed portion of each pulse appearing in the multi-gradation line image data as described above, the multi-gradation line image data including the deformed portion is converted to a standard paper 1 level which is a standard. This is performed by overlapping with the multi-gradation line image data and detecting a portion deviating from the reference image data. As shown in FIG. 3, the CCD line sensor cameras 6a to 6
If the density level of the inspected surface multi-gradation line image data of each width x captured by d matches the density level of the reference multi-gradation line image data A, there is no defect and the inspected surface multi-gradation line image data A has no defect. The density level of the line image data does not match the density level of the reference multi-gradation line image data A, and the density level of the inspection-target multi-gradation line image data is the density level of the reference multi-gradation line image data A. On the other hand, if it appears as a change in pulse shape on either the “bright” side or the “dark” side, it is a defect. However, inconspicuous, in use,
In order to prevent the non-problem defect from being recognized as a defect, the reference multi-gradation line image data A has a certain allowable value for the density level difference between the "bright" side and the "dark" side, that is, light defect density levels D and E. And heavy defect concentration levels F and G are set.

In the defect detection processing section 11, the "bright" side defect 15 in the width x taken by the CCD line sensor camera 6a
Is out of the range of the heavy defect concentration level F on the “bright” side, it is determined that the defect is a heavy defect, and the defect 17 on the “dark” side in the width x captured by the CCD line sensor camera 6b is , The light defect density level E on the “dark” side is determined to be a light defect, and the defect 16 on the “bright” side in the width x imaged by the CCD line sensor camera 6c is “bright”. Is within the range of the light defect density level D on the side, it is determined that the defect is not a defect, and the defect 18 on the “dark” side in the width x imaged by the CCD line sensor camera 6d is the heavy defect density on the “dark” side. Since it is out of the range of the level G, it is determined that the defect is a heavy defect.

In the thickness measurement and the defect inspection as described above,
In particular, for paper, the grammage (the amount of raw material per 1 m ² )
The thickness of the fiber is determined according to the thickness of the fiber, and the fiber is entangled with each other. Therefore, the amount of transmitted light varies (varies) depending on the thickness of the fiber. Under these conditions,
When the light transmission amount is locally measured as in the conventional example, it cannot be said that the thickness of the paper can always be accurately measured. It can be said that it is preferable to measure the thickness based on the averaged data of the transmission amount. The size of the area can be arbitrarily selected.

When measuring the thickness or the like, the reference density managing unit 10 for both ends of the illumination light is used to control the CCD line sensor cameras 6a and 6d.
Light source 3 of illuminating means 2 leaking upward from both sides of paper 1
Is compared with the reference brightness, and the brightness of the light source 3 of the lighting means 2 is feedback-controlled via the lighting power supply unit 5 so as to be almost always constant.
In detecting the density level of the paper 1, it is possible to suppress the influence of the difference in the illuminance of the illumination light, thereby improving the measurement accuracy. Further, in the present embodiment, the temperature in the light transmitting container 4 containing the light source 3 is adjusted by the temperature adjusting means, so that the amount of the illumination light emitted from the light source 3 is always adjusted without being affected by the ambient temperature. The paper 1 can be kept almost constant, and the paper 1 can always be stably illuminated with almost constant illuminance. Therefore, the number of times and the control width of the feedback control for the light source 3 by the illumination light reference density management unit 10 can be suppressed to be extremely small, and the inspection accuracy can be further improved and the reliability of the inspection can be improved. Further, by cooling the light source 3, it is possible to prevent the light source 3 from being damaged at a high ambient temperature, and since the light source 3 is protected by the light transmitting container 4, it is possible to prevent the light source 3 from being damaged. can do. Therefore, occurrence of danger can be prevented, and troublesomeness of cleaning up can be eliminated.

In the above embodiment, the multi-gradation line image data of 256 levels is obtained. However, the desired multi-level line image data of 512 levels or 1024 levels can be obtained. . Further, in the embodiment, the line density data sequentially output from the image input unit 7 is sequentially added in the area density average processing unit 8,
Although the average value is obtained by dividing by the number of pixels, the averaging process may be performed by sequentially integrating (summing) the line image data. In addition, since four line sensor cameras 6a to 6b are used, each of the cameras 6a to 6b is used.
Although the averaging process of the density level is performed for each region imaged in 6d, when only one camera is used, the averaging process of the density levels of all the regions may be performed. Also, instead of a CCD line sensor camera, a large number of sensors can be arranged in a line, and not only line image data but also line data can be obtained. Detection and averaging can also be performed. Further, the area for measuring the thickness may be continuous in the length direction of the light transmitting body, or may be at regular intervals. Furthermore, by using visible light to illuminate a light-transmitting material such as paper as a measurement target, ease of handling, safety, cost reduction, etc. can be achieved, but infrared rays, ultraviolet rays, β rays, r-line,
X-rays and the like can also be used. In addition, the present invention can be variously modified without departing from the basic technical idea.

[0040]

As described above, according to the present invention, the density level due to the light transmission over the entire surface of the light transmitting member is detected, and based on this detection data, almost the entire area in each predetermined region of the light transmitting member is detected. Since the density level data for averaging the density levels is obtained and the thickness of the light transmitting body is measured from the detected averaged density level data, the thickness of the light transmitting body can be accurately measured. Therefore, the reliability of measurement can be improved.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing a thickness measuring device for a light transmitting body according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram illustrating an example of a measurement area of a paper for measuring a thickness according to the embodiment;

FIG. 3 is a diagram illustrating a paper for measuring a thickness according to the embodiment;
FIG. 3 is an explanatory diagram showing multi-gradation line image data on a line ww in FIG. 2.

FIG. 4 is a diagram illustrating the principle of measuring the thickness of paper according to the present embodiment.

FIG. 5 is an explanatory diagram showing an averaged density level of a measurement area according to an actual embodiment of a paper whose thickness is to be measured according to the embodiment;

FIG. 6 is a graph showing the relationship between paper thickness and light transmittance.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Paper (light-transmitting body) 2 Illumination means 6a-6d Black-and-white CCD line sensor camera 7 Image input part 8 Area density average processing part 9 Defect detection processing part 10 Illumination light reference density management part 11 Inspection data processing part 12 Display part

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Seiji Takashiro 1-5 Kagamiba Oyanagicho, Minami-ku, Kyoto Inside Duck Engineering Co., Ltd. (72) Inventor Kazuyo Takahashi No. 1 Kamikaba Oyanagicho, Minami-ku, Kyoto-shi 5 Inside Duck Engineering Co., Ltd. (72) Inventor Front First, 1st Kagamiba Oyanagicho, Minami-ku, Kyoto City 5 Duck Engineering Co., Ltd. (72) Inventor Mitsunao Takahashi No. 1, 1 Kagamiba Oyanagicho, Minami-ku, Kyoto-shi 5 Inside Duck Engineering Co., Ltd. (72) Inventor Yoshitaka Hikami 1-5 Kamikaba Oyanagicho, Minami-ku, Kyoto F-term within Duck Engineering Co., Ltd. 2F065 AA30 AA49 BB01 BB15 BB23 CC02 EE03 FF46 FF67 FF70 GG02 GG03 GG16 GG16 GG24 HH13 HH15 JJ03 JJ05 JJ09 JJ26 NN02 NN17 NN20 QQ03 QQ23 QQ25 QQ27 QQ42 RR06 RR09 3B154 AB22 BA53 BB18 BC4 2 CA13 CA16 CA22 CA29 DA30

Claims (7)

[Claims] 1. A translucent body is illuminated by transmission, and a density level of the translucent body due to light transmission is detected. Based on the detection data, a substantially entire density level in a predetermined region of the translucent body is determined. A method for measuring the thickness of a light-transmitting member, wherein density level data to be averaged is determined, and the thickness of the light-transmitting member is measured from the detected density level data. 2. The method according to claim 1, wherein the detected density level data in each predetermined region of the light transmitting body is compared with reference density level data, and the presence or absence of a thickness defect of the light transmitting body is determined based on whether or not the density level difference is within an allowable range. The method for measuring the thickness of a light transmitting body according to claim 1, wherein: 3. The method for measuring the thickness of a light transmitting body according to claim 1, wherein the detected density level data for each predetermined region of the light transmitting body is obtained from multi-gradation line data sequentially outputted. 4. An illuminating means for illuminating the light transmitting member, a detecting means for detecting a density level of the light transmitting member due to light transmission, and the light transmitting member based on detection data outputted from the detecting means. Means for obtaining density level data for averaging substantially the entirety of the density level in each predetermined area, and measuring the thickness of the light transmitting body from the detected density level data. 5. The method according to claim 1, wherein the detected density level data in each predetermined region of the light transmitting body is compared with reference density level data, and the presence or absence of a thickness defect of the light transmitting body is determined based on whether or not the density level difference is within an allowable range. The apparatus for measuring the thickness of a light-transmitting body according to claim 4, further comprising a determination unit that determines 6. The illuminance of the illumination light from the illuminating means, which is detected by the detecting means and is compared with the illuminance of the illuminating light from the illuminating means leaking from both sides of the translucent body, as a reference illuminance, becomes substantially constant. 6. The light transmitting body thickness measuring apparatus according to claim 4, further comprising control means for performing feedback control of said lighting means. 7. A lighting device comprising: a light source for emitting illumination light;
A light transmitting container for receiving illumination light emitted from the light source so as to transmit the light, and a temperature adjusting means for adjusting the temperature in the light transmitting container to adjust the light amount of the light source substantially constant. 7. The thickness measuring device for a light transmitting body according to any one of 4 to 6.