JPH04328449A - Measuring method and apparatus for moisture - Google Patents

Abstract

PURPOSE:To obtain the two-dimensional distribution of moisture or the local moisture of an object to be measured. CONSTITUTION:An object 1 to be measured is photographed by a photographing device 8 with use of the measuring light in the absorption band of water in the near infrared region which is reflected or permeated at the object 1. The measuring image data corresponding to the dark and bright of the image is stored in a memory 15 for every plurality of pixels constituting the two-dimensional image. Then, the object 1 is photographed by the photographing device 8 with use of the comparison light in the non-absorption band of water in the near infrared region reflected or permeated at the object 1, and the comparison image data corresponding to the dark and bright of the two-dimensional image is stored in a memory 16 for every plurality of pixels constituting the image. Thereafter, the moisture of the object 1 is obtained for every pixel based on the stored measuring image data and comparison image data.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention is applicable to soap, paper, film,
The present invention relates to a method and apparatus for measuring the moisture content of water-containing substances such as tablets and powder using near-infrared rays.

0002

[Prior Art] It has been conventionally carried out to measure the moisture content of a substance containing moisture by irradiating it with near-infrared rays (Japanese Patent Application Laid-Open No. 58-204336, Japanese Patent Application Laid-Open No. 59-1999).
-174739, JP-A-58-7547).

[0003] This method takes advantage of the fact that near-infrared rays of a specific wavelength have a high energy absorption rate by water. That is, FIG. 7 shows the relationship between wavelength and reflectance when water is irradiated with near-infrared rays, and the wavelength is 1.43 μm and 1.94 μm.
The reflectance is small near 3.0 μm and 3.0 μm, indicating that the energy absorption rate by water is high. Near-infrared energy absorption by water increases as the water content of the substance increases, so it can be measured by irradiating the measurement target with measurement light at the absorption wavelength of water and measuring the energy of the reflected or transmitted light. The moisture content of objects can be measured.

However, in measurements using only measurement light in the water absorption wavelength range, changes in the surface condition, color, composition, etc. of the object to be measured act as disturbances, resulting in fluctuations in the measured values. In order to eliminate the effects of such disturbances, the measurement target is irradiated with comparison light in the non-absorbing wavelength band of water, and the energy of the reflected or transmitted light of the comparison light is combined with the reflected or transmitted light of the measurement light. Disturbances are removed by comparing energy.

For example, a two-color infrared system shown in FIGS. 8 and 9 has been adopted. This means that ES is the energy of the measuring light with absorption wavelength λ2 of water before it is reflected or transmitted by the object to be measured, S is the energy after reflection or transmission, and comparison light with non-absorption wavelength λ1 of water is the object to be measured. ER is the energy before being reflected or transmitted by an object.
, if the energy after reflection or transmission is R, and the energy absorption rate by water is m, then S/R=(1-m
) ES /ER. From this formula, if the energies S and R of the measurement light and comparison light after being reflected or transmitted through the measurement object are measured using a photoelectric conversion element or the like,
The energy absorption rate due to moisture in the object to be measured can be determined by removing the influence of the disturbance. Therefore, the moisture content can be calculated from the relationship between the energy absorption rate and moisture determined in advance. The relationship between the energy absorption rate and moisture can be expressed, for example, as shown in FIG.
When the logarithm of /S is taken and the vertical axis is the water content W (%), it can be shown by a calibration curve expressed by the linear approximation formula W=A+Bln(R/S). Note that A and B are coefficients set in advance through calibration.

[0006] Furthermore, it has been attempted to improve the accuracy of moisture measurement by using a plurality of comparison lights in wavelength bands in which water does not absorb water. This is because the spectral characteristics may change due to changes in the surface condition, color, composition, etc. of the measurement target, and the energy of the comparison light after being reflected or transmitted through the measurement target may fluctuate. This improves measurement accuracy by removing fluctuations.

For example, a three-color infrared system shown in FIGS. 10 and 11 has been adopted. This assumes that the change in spectral characteristics due to the influence of the topography of the object to be measured is first-order linear, and the energy after the comparison light with the non-absorption wavelength λ1 of water is reflected or transmitted through the object to be measured is R1 + r, When the energy after the comparison light with the non-absorption wavelength λ3 of water is reflected or transmitted by the measurement object is R2 - r, and the energy before each comparison light is reflected or transmitted by the measurement object is ER1 and ER2. , 2S/(R1
+R2 )=2S/(R1 +r+R2 -r)=(
1-m)2ES/(ER1+ER2). As a result, the energy fluctuation r of the comparison light reflected or transmitted by the measurement object is removed, so the measurement light and each comparison light after being reflected or transmitted by the measurement object using a photoelectric conversion element etc. are removed. Energy S, R1 +r, R
By measuring 2-r, the energy absorption rate due to moisture in the object to be measured can be determined by removing the influence of the formation. Therefore, the moisture content can be calculated from the relationship between the energy absorption rate and moisture determined in advance. The relationship between the energy absorption rate and moisture is, for example, as shown in FIG.
When taking the logarithm of and plotting the moisture W (%) on the vertical axis, W
It can be shown by a calibration curve expressed by the linear approximation formula: =C+Dln[(R1 +R2)/2S]. In addition, C, D
is a coefficient set in advance by calibration.

[0008] Furthermore, measurement accuracy has been improved by using a large number of comparison lights.

FIG. 12 shows a moisture measuring device using the two-color infrared method described above. This moisture measuring device includes a light source 101 that emits light having a continuous spectrum in the near-infrared region, a concave mirror 102, a lens 103, a reflecting mirror 104,
It includes a rotary disk 105 and a motor 106 that rotates the rotary disk 105. The rotary disk 105 includes a filter 105a that transmits only the measurement light in the water absorption wavelength band in the near-infrared region, and a filter 105b that transmits only the comparison light in the water non-absorption wavelength region in the near-infrared region. is installed. In addition, a reflecting mirror 107 and a concave mirror 1
09, a detector 110 containing a photoelectric conversion element, and an arithmetic unit 111.

The light emitted from the light source 101 is transmitted to the concave mirror 1.
02 and a lens 103, is reflected by a reflecting mirror 104, and passes through a filter 105a. As a result, the measuring light in the absorption wavelength band of water is reflected by the reflecting mirror 107 and irradiated onto the measuring object 108 . This measurement light is
Depending on the moisture content of the object to be measured, part of it is absorbed and the rest is reflected. This reflected measurement light is focused by concave mirror 109 and enters detector 110 . As a result, the detector 110 detects a signal corresponding to the energy of the measurement light reflected by the measurement object 108 and the arithmetic unit 1
Output to 11.

[0011] Furthermore, the rotating disk 10 is rotated by the motor 106.
5, the light from the light source 101 passes through the filter 105b via the concave mirror 102, the lens 103, and the reflecting mirror 104, and the measurement object 108 is irradiated with comparative light in a wavelength band that is not absorbed by water. The comparison light irradiated to the measurement object is reflected without being absorbed by the moisture of the measurement object 108, and the reflected comparison light is reflected by the concave mirror 109.
The light is focused by the detector 110 and enters the detector 110. Thereby, the detector 110 outputs a signal corresponding to the energy of the comparison light reflected by the measurement object 108 to the calculation device 111. Then, the calculation device 111 calculates the moisture content of the measurement object 8 from the energy of the measurement light and comparison light reflected on the measurement object 108.

0012

[Problems to be Solved by the Invention] Conventional moisture measurement using near-infrared rays is to find the average moisture content in the entire measurement area where the measuring object is irradiated with measurement light and comparison light. It was not possible to determine local moisture. For example, soap will not dissolve uniformly if the moisture distribution is uneven, so it is desirable to measure the moisture distribution and local moisture in the measurement area for quality control. It was not possible to respond by measuring moisture.

[0013] An object of the present invention is to solve the problems of the prior art described above.

[0014]

[Means for Solving the Problems] The moisture measuring method according to the present invention is characterized in that the measuring object is measured by measuring light in the absorption wavelength band of water in the near-infrared region that is reflected or transmitted by the measuring object. For each of the multiple pixels that make up the two-dimensional image, measurement image data is stored according to the brightness of the image, and the non-absorption wavelength of water in the near-infrared region that is reflected or transmitted by the measurement object is stored. An image of the object to be measured is taken using a band of comparative light, and comparative image data corresponding to the brightness of the image is stored for each of a plurality of pixels constituting the two-dimensional image, and then the stored measurement image data and the comparative image are stored. The point is to determine the moisture content of the object to be measured for each pixel from the data.

In the moisture measurement method according to the present invention, light having a continuous spectrum in the near-infrared region is irradiated toward the object to be measured, and before or after the irradiated light is reflected or transmitted through the object, water is detected. The measurement light is selected from the irradiation light using a filter that transmits only the measurement light in the absorption wavelength band, and the selected measurement light is used to image the object to be measured, and the light having a continuous spectrum in the near-infrared region is measured. The irradiated light is irradiated toward the target object, and before or after the irradiated light is reflected or transmitted by the target object, the comparative light is separated from the irradiated light using a filter that transmits only the comparative light in the wavelength range that water does not absorb. It is preferable that the object to be measured be imaged using the selected comparison light.

The moisture measuring device according to the present invention is characterized by the use of near-infrared irradiation means, measurement light in the water absorption wavelength range in the near-infrared region, and comparison light in the water non-absorption wavelength range. An imaging device capable of capturing an image of a target object, a measurement image storage device that stores measurement image data corresponding to the brightness of the image for each of a plurality of pixels constituting a two-dimensional image captured using the measurement light, and a comparison light for the measurement image. a comparison image storage means for storing comparison image data corresponding to the brightness and darkness of the image for each of a plurality of pixels constituting a two-dimensional image captured by the method; The present invention is characterized in that it includes a calculation means for calculating .

The moisture measuring device according to the present invention includes a light source capable of irradiating a measuring object with light having a continuous spectrum in the near-infrared region, and a measuring light source that emits only measurement light in the water absorption wavelength band in the near-infrared region. It is preferable to include a filter that transmits light and a filter that transmits only comparison light in a wavelength band in which water is not absorbed in the near-infrared region.

[0018]

[Operation] The present invention is based on the following principle.

When an image of the object to be measured is taken using measuring light in the absorption wavelength band of water that is reflected or transmitted through the object, the two-dimensional image has a distribution of brightness and darkness corresponding to the water distribution of the object to be measured. This is because the energy absorption of the measurement light is large in areas with a lot of moisture in the measurement object, so the two-dimensional image created by the measurement light reflected or transmitted by the measurement object becomes dark, and in areas with less moisture, the two-dimensional image is dark. Because the energy absorption of the measurement light is small, the measurement light reflected or transmitted by the measurement object is
Due to the fact that the dimensional image becomes brighter. Therefore, when the two-dimensional image is divided into a plurality of pixels, the measurement image data for each pixel according to the brightness of the image becomes data corresponding to the moisture distribution of the measurement object.

On the other hand, when the measurement object is imaged using comparison light in the non-absorbing wavelength band of water that is reflected or transmitted through the measurement object, the two-dimensional image is not affected by the water content of the measurement object, but It has brightness and darkness depending on the surface condition, color, composition, etc. of the object. When this two-dimensional image is divided into multiple pixels, the comparison image data for each pixel according to the brightness and darkness of the image is data that is affected by the texture of the object to be measured, similar to the measurement image data for the corresponding pixel. becomes. Therefore, by using the measurement image data and the comparison image data, the moisture content of the measurement object can be determined for each pixel while removing the influence of the texture of the measurement object.

Note that the comparison image data may be obtained after the measurement image data is obtained, or the measurement image data may be obtained after the comparison image data is obtained.

When a single comparison light is used, the water content can be determined for each pixel by the two-color infrared method described above. When using a plurality of comparison lights, the water content can be determined for each pixel using the aforementioned three-color infrared method or the like.

When the object to be measured is non-transparent, the object to be measured is imaged using the measurement light and comparison light reflected from the object. However, in the case of an object to be measured that is transparent, such as paper or film, The measurement object can be imaged using the measurement light and the comparison light that are transmitted through the measurement object.

By using a filter that transmits only the measuring light in the water absorption wavelength band in the near-infrared region, it is possible to select the measuring light from light having a continuous spectrum in the near-infrared region. By using a filter that transmits only the comparison light in the non-absorption wavelength band of water in the area, the comparison light can be selected from the light having a continuous spectrum in the near-infrared region. The selection of measurement light and comparison light using this filter may be performed before the light having a continuous spectrum is reflected or transmitted through the measurement object, or after the light having a continuous spectrum is reflected or transmitted through the measurement object. When sorting light with a continuous spectrum before it is reflected or transmitted through the measurement target, a filter is placed between the light source and the measurement target, and the light with a continuous spectrum is filtered before it is reflected or transmitted through the measurement target. If sorting is to be performed after the object has been measured, a filter is placed between the object to be measured and the image sensor.

As the imaging means for the object to be measured, it is preferable to use a television camera having an imaging element such as an imaging tube or a solid-state image element that has spectral sensitivity to the wavelengths of the measurement light and comparison light. Further, as a storage means for storing image data for each of a plurality of pixels constituting an image, a computer capable of storing a digital image signal for each pixel obtained by converting an analog image signal into a digital signal with an AD converter is used. An example of this is the built-in image memory. Another example is a frame memory that can convert an analog image signal into a digital signal and store it as a digital image signal for each pixel. Furthermore, as the calculating means for calculating the moisture content for each pixel, a computer having a memory area corresponding to the number of pixels is preferable. As a result, an imaging device with spectral sensitivity to near-infrared rays is used to capture a two-dimensional image of the object to be measured using near-infrared rays that have been absorbed by moisture, and this image signal is converted into a digital signal that can be processed by a computer. By storing the image data in the storage means as image data for each pixel constituting the image data, it is possible to measure the local moisture or moisture distribution state of the measurement object, which has been difficult with conventional techniques.

[0026]

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows the configuration of a moisture measuring device according to an embodiment of the present invention. This moisture measuring device includes a light source 2 that uniformly irradiates an object 1 to be measured with light having a continuous spectrum in the near-infrared region. As the light source 2, for example, a halogen lamp is used. A rotating disk 5 is disposed in the optical path of the light emitted from the light source 2 and the reflected light from the measurement object 1 . This rotating disk 5 includes a filter 3 that transmits only measurement light in the water absorption wavelength band in the near-infrared region.
and a filter 4 that transmits only comparative light in the non-absorption wavelength band of water in the near-infrared region. By rotationally driving this rotating disk 5 by a motor (not shown), the filters 3 and 4 are arranged at a transmission position (the left position in FIG. 1) where the reflected light from the measurement object 1 is transmitted, and at which the reflected light is reflected. The position is changed to a non-transmissive position out of the optical path of the light.

In order to image the measurement object 1 using the light transmitted through the filters 3 and 4, a lens 6 is used.
and a television camera 7 having an image sensor 8 are provided. The lens 6 forms a two-dimensional image of the object 1 to be measured on the imaging surface of the image sensor 8 . Its imaging magnification is lens 6
A desired magnification can be obtained by selecting .

The image pickup device 8 is, for example, an image pickup tube or a solid-state image device, and is sensitive to measurement light in the water absorption wavelength band in the near-infrared region and comparison light in the water non-absorption wavelength band. Use what you have. The television camera 7 outputs an image signal of the measurement object 1 captured by the image sensor 8 . An AD converter 9 is provided to digitize this image signal. Further, a monitor television 10 is provided to monitor the two-dimensional image captured by the television camera 7.

The image signal converted into a digital signal by the AD converter 9 is input to the microcomputer 11. The microcomputer 11 includes an input/output interface 12, a central processing unit 13, a main storage 14, a measurement image memory 15, and a comparison image memory 16.

The central processing unit 13 processes the digitized image signal input from the input/output interface 12 according to a program stored in the main storage device 14. First, an image signal of the measurement object 1 captured by the measurement light reflected from the measurement object 1 is converted into a measurement image data for each of a plurality of pixels constituting the two-dimensional image as measurement image data according to the brightness of the image. memory 15 for use. In addition, the image signal of the measurement object 1 captured by the comparison light reflected on the measurement object 1 is stored in a comparison image memory as comparison image data according to the brightness and darkness for each of the plurality of pixels constituting the two-dimensional image. 16 to be memorized.

[0032] The central processing unit 13 also has a main memory 14.
According to the program stored in the comparison image memory 16
Moisture content is calculated for each pixel constituting the two-dimensional image using the image data stored in the measurement image memory 15 and the image data stored in the measurement image memory 15. This calculated moisture content for each pixel is displayed on a display device 17 connected to the interface 12. Further, an external storage device 19 such as a floppy disk for storing data stored in the measurement image memory 15 and the comparison image memory 16 is connected to the interface 12 .

The moisture measuring method using the moisture measuring device described above will be explained with reference to the flowchart shown in FIG.

First, by rotating the rotary disk 5, the filter 3, which transmits only the measuring light in the wavelength band absorbed by water, is positioned at the transmitting position. Next, turn on the light switch
By doing so, the measurement object 1 is irradiated with light from the light source 2. This irradiation light is reflected from the measurement object 1 and passes through the filter 3, so the measurement light is selected from the irradiation light, and an image of the measurement object 1 created by the selected measurement light is captured by the lens 6 and captured by the television camera 7. An image is formed on the imaging surface of the image sensor 8. Focus adjustment during image formation is performed by displacing the position of the lens 6 while visually viewing the monitor television 10. The brightness of this captured two-dimensional image corresponds to the magnitude of the energy of the measurement light reflected on the measurement object 1, and therefore corresponds to the moisture distribution of the measurement object 1. This image signal of the imaged object to be measured 1 is converted into a digital signal by the AD converter 9, and is input to the microcomputer 11 as measurement image data corresponding to the brightness and darkness of the image. This measurement image data is stored in the measurement image memory 15 for each of a plurality of pixels forming the image. The number of pixels is determined depending on the measurement accuracy and the capacity of the memory 15. In this embodiment, an image is divided into 512×512 pixels and stored. Further, the degree of brightness and darkness of the image is stored in 256 gradations.

Next, the rotary disk 5 is rotated, and the filter 4, which transmits only the comparative light in the wavelength band that water does not absorb, is positioned at the transmitting position. As a result, the light irradiated from the light source 2 is reflected by the measurement object 1 and transmitted through the filter 4, so that the comparison light is selected from the irradiation light, and the image of the measurement object 1 is created by the selected comparison light. An image is formed by the lens 6 onto the imaging surface of the image sensor 8 of the television camera 7 . This image signal of the object to be measured 1 is sent to an AD converter 9.
The digital signal is converted into a digital signal and inputted to the microcomputer 11 as comparison image data corresponding to the brightness and darkness of the image. This comparison image data is stored in the comparison image memory 16 for each of a plurality of pixels forming an image. The number of pixels is the same as when storing measurement image data.

Next, for each pixel constituting the image, a correction calculation is performed to remove the influence of the surface condition, color, composition, etc. of the measurement object 1 using the two-color infrared method described in the prior art. This is done by a microcomputer. Specifically, for each pixel of 512 x 512, measurement image memory 1
5 includes measurement image data S1,1, S1,2 according to the energy of the measurement light reflected on the measurement object 1.
...S512,512 are stored, and the comparison image memory 16 stores comparison image data R1,1, R1,2 corresponding to the energy of the comparison light reflected on the measurement object 1.
... Since R512,512 are stored, Ri,j /Si
, j (i=1-512, j=1-512) are calculated.

Thereafter, the microcomputer 11 calculates the moisture content for each pixel forming the image. For example, it is calculated using a calibration curve expressed by the linear approximation formula described in the related art. Specifically, Wi,j =A+BI
n(Ri,j/Si,j)(i=1~512,j=
1 to 512), the moisture Wi,j (%) for each pixel is calculated.

The moisture content of each pixel determined in this way is displayed on the display device 17. This display device 17 can be, for example, a CRT display or a printer that displays a histogram of moisture distribution, a contrast image of moisture distribution, or a local numerical value of the measurement object 1 as shown in FIGS. 5 and 6. The histograms of moisture distribution shown in FIGS. 5 and 6 show the results of measuring the moisture of papers with different moisture distributions using the moisture measuring device described above. The horizontal axis is moisture content (%)
The vertical axis shows the frequency at which pixels with the same water content appear as a percentage of the total number of pixels. From this, it can be seen that the paper shown in FIG. 5 has a more uniform moisture distribution than the paper shown in FIG. 6.

Note that the present invention is not limited to the above embodiments.

For example, the microcomputer 11 has a second
By providing a comparison image memory 20 and providing a filter 21 on the rotating disk 5 that transmits only the second comparison light having a non-absorption wavelength of water in the near-infrared region, three
The moisture content of the measurement object 1 can be determined by employing a color infrared method. A measurement method using the three-color infrared method will be described with reference to the flowchart shown in FIG.

First, by rotating the rotary disk 5, the filter 3, which transmits only the measurement light in the wavelength band absorbed by water, is positioned at a transmitting position. Next, turn on the light switch
By doing so, the measurement object 1 is irradiated with light from the light source 2. This illumination light is reflected by the measurement object 1 and passes through the filter 3, so that the measurement light is selected from the irradiation light, and the image of the measurement object 1 created by the selected measurement light is captured by the lens 6 on the television camera 7. An image is formed on the imaging surface of the image sensor 8. The image signal of the object to be measured 1 thus imaged is converted into a digital signal by the AD converter 9, and inputted to the microcomputer 11 as measurement image data corresponding to the brightness and darkness of the image. This measurement image data is stored in the measurement image memory 15 for each of a plurality of pixels forming the image.

Next, the rotary disk 5 is rotated, and the filter 4, which transmits only the first comparative light in the wavelength band in which water is not absorbed, is positioned at the transmitting position. As a result, the light emitted from the light source 2 is reflected by the measurement object 1 and transmitted through the filter 4, so that the first comparison light is selected from the emitted light,
An image of the object to be measured 1 based on the selected first comparison light is formed by a lens 6 onto an image pickup surface of an image pickup element 8 of a television camera 7. The image signal of the object to be measured 1 thus imaged is converted into a digital signal by the AD converter 9, and inputted to the microcomputer 11 as first comparative image data according to the brightness and darkness of the image. This first comparison image data is stored in the first comparison image memory 16 for each of a plurality of pixels constituting the image. The number of pixels is the same as when storing measurement image data.

Next, the rotary disk 5 is rotated, and the filter 21, which transmits only the second comparison light in the wavelength band in which water is not absorbed, is positioned at the transmitting position. As a result, the light irradiated from the light source 2 is reflected by the measurement object 1 and the filter 2
1, the second comparison light is selected from the irradiation light, and an image of the measurement object 1 based on the selected second comparison light is focused by the lens 6 on the imaging surface of the image sensor 8 of the television camera 7. imaged. The image signal of the object to be measured 1 thus imaged is converted into a digital signal by the AD converter 9, and the microcomputer 11 receives a second signal corresponding to the brightness and darkness of the image.
It is input as comparison image data. This second comparison image data is stored in the second comparison image memory 20 for each of a plurality of pixels forming an image. The number of pixels is the same as when storing measurement image data.

Next, for each pixel constituting the image, a correction calculation is performed to remove the influence of the surface condition, color, composition, etc. of the object to be measured 1 using the three-color infrared method described in the prior art. This is performed by the microcomputer 11. Specifically, for each pixel of 512 x 512, the measurement image memory 15 stores measurement image data S1,1, S1,2 corresponding to the energy of the measurement light reflected on the measurement object 1.
... S512, 512 are stored, and the first comparison image memory 16 stores first comparison image data R1 corresponding to the energy of the first comparison light reflected on the measurement object 1.
1,1, R11,2...R1512,512 are stored, and the second comparison image memory 20 stores second comparison image data R21 corresponding to the energy of the second comparison light reflected on the measurement object 1. ,1 ,R21,2...
Since R2512,512 is stored, (R1i,j +R2i
,j)/2Si,j (i=1~512, j=1~5
12) is calculated.

Thereafter, the microcomputer 11 calculates the moisture content for each pixel forming the image. For example, it is calculated using a calibration curve expressed by the linear approximation formula described in the related art. Specifically, Wi,j =A+BI
n((R1i,j +R2i,j)/2Si,j)
(i=1 to 512, j=1 to 512), the moisture content Wi,j (%) of each pixel is calculated.

Furthermore, in the above embodiment, the object to be measured is imaged using the light reflected from the object to be measured 1, but in the case of the object to be measured 1 which is translucent, as shown by the broken line in FIG. Alternatively, the light source 2' may be provided at a position facing the image sensor 8 with the measurement object 1 in between, and the measurement object 1 may be imaged by light transmitted through the measurement object 1.

[0047] Furthermore, if measurements are made continuously over a long period of time, the sensitivity of the image element 8 may change due to heat. To prevent this change from becoming an error, the microcomputer 1
1 may be provided with a background image memory 22, and the image data may be modified as shown in FIG.

First, a filter that transmits only measurement light or comparison light is positioned at a transmission position. Next, by turning on the lighting switch, the light from the light source 2 is transmitted to the measurement target 1.
irradiate. This irradiation light is reflected by the measurement object 1 and passes through the filter, so that an image of the measurement object 1 by the measurement light or comparison light is formed by the lens 6 on the imaging surface of the image sensor 8 of the television camera 7. . The image signal of the object to be measured 1 thus imaged is converted into a digital signal by the AD converter 9, and inputted to the microcomputer 11 as image data corresponding to the brightness and darkness of the image. This image data is stored in the image memory for each of a plurality of pixels forming an image.

Next, the illumination is turned off, a background image is captured by the image sensor 8, and the image signal is sent to the AD.
The converter 9 converts it into a digital signal and inputs it to the microcomputer 11 as background image data. This background image data is stored in the background image memory 22 for each of a plurality of pixels forming the image.

Next, the image data stored in the image memory is corrected for each of the plurality of pixels constituting the image. Specifically, the difference between the pixel-by-pixel image data stored in the image memory and the pixel-by-pixel background image data stored in the background image memory 22 is set as corrected measured image data or comparison image data, A new image is stored in the image memory. Thereby, moisture can be determined without being affected by sensitivity changes due to heat of the image sensor 8.

[0051] Also, the number of pixels constituting the image, the area of the object to be measured corresponding to one pixel, the level of encoding when converting the image signal into a digital signal, the output intensity of the light source, and the television camera used when capturing the image. It is preferable to change the aperture stop according to measurement accuracy.

Furthermore, the moisture content may be calculated using image data stored in the external storage device 19.

[0053]

According to the moisture measuring method and moisture measuring device according to the present invention, it is possible to determine the two-dimensional moisture distribution and local moisture of the object to be measured.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of the configuration of a moisture measuring device according to an embodiment of the present invention.

FIG. 2 is a flowchart showing a moisture measurement method according to an embodiment of the present invention.

FIG. 3 is a flowchart showing a moisture measurement method according to different embodiments of the present invention.

FIG. 4 is a flowchart showing a method for correcting image data according to an embodiment of the present invention.

[Fig. 5] Histogram showing the moisture distribution of the measurement object determined by the moisture measurement method according to the present invention.

[Fig. 6] Histogram showing the moisture distribution of the measurement object determined by the moisture measurement method according to the present invention.

[Figure 7] Diagram showing the relationship between infrared wavelength and reflectance

[Figure 8]
Diagram of two-color infrared system

[Figure 9] Diagram showing the calibration curve of the two-color infrared method

[Figure 10] 3
Explanation diagram of color infrared method

[Figure 11] Explanatory diagram showing the calibration curve of the three-color infrared method

[Figure 1
2] Explanatory diagram of the configuration of a conventional moisture measuring device

[Explanation of symbols]

1 Object to be measured 2. Light source 8 Image sensor 15 Memory for measurement images 16 Comparison image memory

Claims (4)

[Claims] Claim 1: An image of the measurement object is captured using measurement light in the absorption wavelength band of water in the near-infrared region that is reflected or transmitted by the measurement object, and an image is captured for each of a plurality of pixels constituting the two-dimensional image. In addition to storing measurement image data according to the brightness and darkness of the measurement object, the measurement object is imaged using comparison light in the near-infrared non-absorbing wavelength range of water that is reflected or transmitted by the measurement object, and the two-dimensional image is created. It is characterized by storing comparative image data corresponding to the brightness and darkness of the image for each of the plurality of constituent pixels, and then determining the moisture content of the object to be measured for each pixel from the stored measurement image data and comparative image data. Moisture measurement method. 2. Light having a continuous spectrum in the near-infrared region is irradiated toward the measurement object, and measurement light in the water absorption wavelength band is applied before or after the irradiation light is reflected or transmitted by the measurement object. The measurement light is selected from the irradiation light using a filter that only transmits light, and the object to be measured is imaged using the selected measurement light, and light with a continuous spectrum in the near-infrared region is irradiated toward the object to be measured. Then, before or after this irradiated light is reflected or transmitted through the measurement object, the comparative light is selected from the irradiated light using a filter that transmits only the comparative light in the non-absorbing wavelength band of water, and this selected comparison 2. The moisture measuring method according to claim 1, wherein the measuring object is imaged using light. 3. An imaging means capable of imaging an object to be measured using near-infrared irradiation means, measurement light in a water absorption wavelength range in the near-infrared region, and comparison light in a water non-absorption wavelength range; measurement image storage means for storing measurement image data corresponding to the brightness and darkness of the image for each of a plurality of pixels forming a two-dimensional image captured by the measurement light; It is characterized by comprising a comparison image storage means for storing comparison image data according to the brightness and darkness of the image for each pixel, and a calculation means for calculating moisture for each pixel from the stored measurement image data and comparison image data. moisture measuring device. 4. A light source capable of emitting light having a continuous spectrum in the near-infrared region toward a measurement target, a filter that transmits only measurement light in the water absorption wavelength band in the near-infrared region, and 4. The moisture measuring device according to claim 3, further comprising a filter that transmits only comparative light in a non-absorbing wavelength band of water in an infrared region.