JP6580937B2 - Inspection apparatus and inspection method - Google Patents

Description

  The present invention relates to an inspection apparatus and an inspection method for inspecting the quality of an object to be inspected such as food, pharmaceuticals, and plastics using a near-infrared camera, and in particular, the quality of a granular object to be inspected during transportation. The present invention relates to an inspection apparatus and inspection method suitable for in-line high-speed inspection.

  Conventionally, as a technique for inspecting the quality of an object to be inspected, such as food, pharmaceuticals, and plastics, there is a technique described in Patent Document 1. The technique described in Patent Document 1 utilizes the property that near-infrared light is absorbed depending on the molecular structure and quality state of the inspection object, and irradiates the inspection object with near-infrared light. Inspecting the inspection object by detecting the amount of near-infrared light reflected by the inspection object or the near-infrared light transmitted through the inspection object in the light and analyzing the detected light amount It is a thing.

JP 2012-8098 A

However, in the technique described in Patent Document 1, in order to suppress the influence of the light amount fluctuation of the near-infrared light irradiation light source, there is a problem that it is necessary to frequently perform the measurement of the reference light in the absence of the inspection object. was there.
In addition, when irradiating near-infrared light onto an inspection object and performing inspection based on the amount of reflected light, when applying to an inspection object having a curved surface such as a granular inspection object, Since the incident angle and the light receiving angle incident on the light detector (camera) fluctuate, there is a problem that the quality of light that is detected by the light detector changes and reliable quality inspection cannot be performed.
An object of the present invention is to provide an inspection apparatus and an inspection method capable of suppressing a decrease in inspection accuracy, paying attention to the above points.

One aspect of the present invention is a near-infrared light irradiating unit that irradiates near-infrared light on an object to be inspected, a first light amount detecting unit that detects the amount of near-infrared light in a predetermined first wavelength range, A second light amount detector that detects the amount of near-infrared light in a second wavelength region different from the first wavelength region, and absorption due to the quality of the inspection object compared to near-infrared light in the first wavelength region and the second wavelength region A third light amount detector that detects the amount of near-infrared light in a reference wavelength range in which the rate of change is small, and is reflected by the inspection object out of the near-infrared light irradiated by the near-infrared light irradiator A near-infrared light detection camera that causes the first light amount detection unit, the second light amount detection unit, and the third light amount detection unit to receive the received near-infrared light or the near-infrared light transmitted through the inspection object, and the first light amount The third light quantity detection unit detects the near-infrared light quantity in the first wavelength range detected by the detection unit and the near-infrared light quantity in the second wavelength range detected by the second light quantity detection unit. Normalized by dividing by the amount of near-infrared light of sub-wavelength region, by analyzing the light intensity after normalization, and a test unit for inspecting the object to be inspected, said first wavelength range, 1180 [Nm] to 1240 [nm] as a central wavelength, the second wavelength range from 1400 [nm] to 1460 [nm] as a central wavelength, and the reference wavelength range from 1560 [nm] to 1620 [nm]. ] and wherein to Rukoto the center wavelength less.

  According to one aspect of the present invention, for example, the surface reflectance or transmittance of the object to be inspected or the amount of light emitted from the near-infrared irradiation unit changes, and the amount of near-infrared light reflected by the object to be inspected or transmitted is changed. Even when the amount of near-infrared light is changed, quality determination is performed based on the normalized light amount in the first wavelength region and light amount in the second wavelength region obtained by dividing by the light amount in the reference wavelength region. As a result, high-accuracy quality inspection becomes possible.

It is a conceptual diagram showing schematic structure of an inspection apparatus. It is a conceptual diagram showing schematic structure of a near-infrared-light three wavelength line sensor camera. It is a flowchart showing an inspection process. It is a graph for demonstrating the inspection method of a to-be-inspected object. 6 is a graph showing the results of Comparative Example 1. 10 is a graph showing the results of Comparative Example 2. 10 is a graph showing the results of Comparative Example 3.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
In the present embodiment, the present invention is applied to an inspection apparatus 1 for inspecting an inspection object 6. Examples of the inspection of the inspection object 6 include determination of a non-defective product and a defective product of the inspection object 6, specification of an abnormal part of the inspection object 6, and determination of different types of the inspection object 6.
This embodiment exemplifies an apparatus and a method for embodying the technical idea of the present invention, and the technical idea of the present invention describes the shape, structure, arrangement, and the like of components as follows. It is not something specific. The technical idea of the present invention can be variously modified within the technical scope defined by the claims described in the claims.

(Constitution)
As shown in FIG. 1, an inspection apparatus 1 according to this embodiment includes an inspection object transport unit 2, a near infrared light line illumination 3 (“near infrared light irradiation unit” in a broad sense), and a near infrared three A wavelength line sensor camera 4 (“near infrared light detection camera” in a broad sense) and an inspection personal computer 5 (“inspection unit” in a broad sense) are provided.
The inspection object conveyance unit 2 conveys the inspection object 6 in a specific direction. For example, a belt conveyor or a pallet conveyor can be adopted. In the example of FIG. 1, as the inspection object conveyance unit 2, an endless belt 210 is stretched between two parallel rollers, and the inspection object 6 is placed on the upper surface of the endless belt 210 (“conveying surface” in a broad sense). A belt conveyor that is placed and transported is used. On the upper surface (conveying surface) of this endless belt 210, an example is shown in which granular materials such as beans, rice, tablets, resin pellets, etc. are spread and conveyed as the inspected object 6.

  The near-infrared light line illumination 3 is disposed above the endless belt 210, and intersects in a plan view (hereinafter referred to as “width direction”) with a direction in which the inspection object 6 is transported (hereinafter also referred to as “transport direction”). Near-infrared light (for example, a wavelength region of 1000 [nm] or more and 1700 [nm] or less) is emitted to a linear region 220 extending in a straight line. As the type of the near-infrared light line illumination 3, halogen illumination, LED, or the like can be adopted. The region 220 extends from one end to the other end in the width direction of the endless belt 210, and is near red to the granular material that has entered the region 220 among the granular materials (inspected object 6) conveyed by the inspection object conveying unit 2. External light is irradiated one after another.

In the present embodiment, an example in which near-infrared light is irradiated to the linear region 220 extending in the width direction on the upper surface (conveying surface) of the endless belt 210 has been described, but other configurations are employed. You can also For example, any region including the linear region 220 on the upper surface (conveying surface) of the endless belt 210 may be used, and a wider region may be irradiated with near infrared light. Moreover, it is also possible to perform inspection while allowing the object to be inspected 6 to fall freely. In this case, the object to be inspected part 2 is not required.
As shown in FIG. 2, the near-infrared three-wavelength line sensor camera 4 collects near-infrared light reflected by the inspection object 6 out of the near-infrared light irradiated by the near-infrared light line illumination 3. The lens system 410 is configured. That is, the lens system 410 reflects near-infrared light reflected by the inspection object 6, that is, near-infrared light reflected by the inspection object 6 that has entered the linear region 220 on the upper surface (conveying surface) of the endless belt 210. Condensing. Further, the near-infrared three-wavelength line sensor camera 4 has a dichroic mirror at the interface, and the near-infrared light condensed by the lens system 410 is divided into three different wavelength ranges (hereinafter referred to as “first wavelength range”, “ It includes three spectroscopic prisms 420 that divide into near-infrared light in the “second wavelength range” and “reference wavelength range”. A vapor deposition film that selectively transmits only near-infrared light in the first wavelength region is deposited on a surface of the spectroscopic prism 420 facing a first line sensor 430 (described later). Thereby, the deposited film forms a bandpass filter. Further, the half-value width λw of near-infrared light received by the first line sensor 430 is specified by the characteristics of the bandpass filter.

  Similarly, a deposition film (bandpass filter) that selectively transmits only near-infrared light in the second wavelength range is deposited on the surface facing the second line sensor 440 (described later), and the third line sensor 450 is deposited. A deposition film (bandpass filter) that selectively transmits only near-infrared light in the reference wavelength region is deposited on the surface facing (described later). As the first wavelength region and the second wavelength region, for example, a wavelength region in which a component that affects the quality of the inspection object 6 is absorbed can be employed. For example, when the quality of the inspection object 6 is affected by the amount of moisture, about 1450 [nm] or about 1940 [nm] which is the absorption wavelength of water is used. In addition, as the reference wavelength range, for example, near infrared light in a wavelength range in which the change in the absorption rate is small depending on the quality of the inspection object 6 compared to near infrared light in the first wavelength range and the second wavelength range can be adopted. For example, near-infrared light having a wavelength range where the change in absorptance due to the quality of the inspection object 6 is 10% or less, preferably a wavelength range of several% or less, can be employed.

As a method for setting the center wavelength λ1 of the first wavelength range, the center wavelength λ2 of the second wavelength range, the center wavelength λ0 of the reference wavelength range, the first wavelength range, the second wavelength range, and the half-value width λw of the reference wavelength range Can adopt, for example, a method in which a spectrum of a substance (beans, rice, etc.) to be inspected 6 is measured by FT-IR (Fourier transform infrared spectroscopy) and the measurement result is analyzed and set. The spectrum is measured using a large number of samples having different quality conditions.
In addition, as a result of experiments using various organic substances as the inspected object 6, the inventor of the present invention sets the center wavelength λ1 of the first wavelength range to 1180 [nm] or more and 1240 [nm] or less, and the second The center wavelength λ2 of the wavelength range is 1400 [nm] or more and 1460 [nm] or less, the center wavelength λ0 of the reference wavelength range is 1560 [nm] or more and 1620 [nm] or less, the first wavelength range, the second wavelength range, and the reference It has been found that the inspection apparatus 1 can be effectively used for inspection of many organic substances (inspection object 6) by setting the half-value width λw of the wavelength region to 30 [nm] or more and 200 [nm] or less.

  The near-infrared three-wavelength line sensor camera 4 is attached to the spectroscopic prism 420, forms near-infrared light in the first wavelength region divided by the spectroscopic prism 420 (receives light), and the amount of the near-infrared light. The first line sensor 430 (in a broad sense, the “first light amount detection unit”) is configured to detect. Similarly, a second line sensor 440 (in a broad sense, “second” is attached to the spectroscopic prism 420 and forms (receives) near-infrared light in the second wavelength range and detects the amount of the near-infrared light. A third light sensor 450 (in a broad sense, a “third light amount detector”) that forms (receives) near infrared light in the reference wavelength region and detects the light amount of the near infrared light. It is comprised including. That is, each of the first line sensor 430, the second line sensor 440, and the third line sensor 450 is near-infrared light reflected by the inspection object 6, that is, a linear region on the upper surface (conveying surface) of the endless belt 210. The near-infrared light reflected by the inspection object 6 that has entered 220 is imaged (received) to detect the amount of light.

As the first line sensor 430, the second line sensor 440, and the third line sensor 450, for example, an 512-pixel InGaAs line sensor image sensor can be employed.
Near-infrared light reflected at the same location of the inspection object 6 is imaged on the corresponding pixels of the line sensors 430, 440, and 450, that is, the pixels at positions corresponding to each other. Further, the pixels at the positions corresponding to each other are aligned so that the imaging field of view matches with an accuracy of 1/4 or less of the pixel size.
Each of the first line sensor 430, the second line sensor 440, and the third line sensor 450 has a predetermined set time, that is, a time represented by the reciprocal of the line rate (for example, 8 [kHz]). Each time, the amount of near infrared light received during the set time is detected. This light quantity detection value is converted into a digital signal by an electric circuit unit inside the camera (hereinafter also referred to as “imaging luminance signal”), and then output to the inspection personal computer 5.

Note that a plurality of near-infrared three-wavelength line sensor cameras 4 may be arranged side by side along the width direction in accordance with the inspection length of the inspection object 6 in the width direction and the required imaging resolution.
The inspection personal computer 5 receives, via the image capture board 510, the imaging luminance signal Iλ1 in the first wavelength range detected by the first line sensor 430, the imaging luminance signal Iλ2 in the second wavelength range detected by the second line sensor 440, and The imaging luminance signal Iλ0 in the reference wavelength range detected by the third line sensor 450 is read, and inspection processing is executed based on these signals. Details of the inspection process will be described later.

The inspection personal computer 5 displays the inspection result on the display 520.
In addition, when the conveyance speed of the inspection object 6 is not constant, an encoder for detecting the conveyance speed is provided, and the encoder pulse output from the encoder is taken into the inspection personal computer 5, and the first line sensor 430, the second line The imaging timing of the sensor 440 and the third line sensor 450 may be synchronized with the encoder pulse so that the imaging resolution in the transport direction is constant. In this case, the inspection personal computer 5 further includes a counter board or the like for taking in the encoder signal.

The inventor of the present invention inspected various inspected objects 6 such as foods, pharmaceuticals, and plastics, and as a result of intensive studies, the following findings (1) to (3) were obtained.
(1) In order to obtain sufficient inspection accuracy, one or two of the infrared light wavelength regions used for the inspection of the inspection object 6 is insufficient, and needs to be three or more. .
(2) If appropriate three wavelength ranges are selected, sufficient inspection accuracy can be obtained with many inspection objects 6.
From the above (1) and (2), the present invention has a configuration for detecting the light amounts Iλ1, Iλ2, and Iλ0 in the three wavelength regions of near infrared light, that is, the first wavelength region, the second wavelength region, and the reference wavelength region. did.

(3) When inspecting using the light amounts in the three wavelength regions, the absorption wavelength band of the component that affects the quality of the inspection object 6 in all three wavelength regions, that is, the quality of the inspection object 6 Rather than assigning to the contributing wavelength band, it is more accurate to assign one of the three wavelength bands to the wavelength band that does not contribute to the quality of the inspection object 6 (hereinafter also referred to as “reference wavelength band”). Is possible. Then, instead of handling the light amounts Iλ1, Iλ2, and Iλ0 in the three wavelength regions in parallel, the ratio of Iλ1, Iλ2 and the light amount Iλ0 in the reference wavelength region is used as Iλ1 / Iλ0, Iλ2 / Iλ0. It is very effective to inspect the object 6.
From the above (3), in the present embodiment, the detected light amount Iλ1 in the first wavelength region and the detected light amount Iλ2 in the second wavelength region are normalized by the light amount Iλ0 in the reference wavelength region, and the normalized light amounts Iλ1 / Iλ0 and The inspection object 6 is inspected by analyzing Iλ2 / Iλ0.

(Inspection process)
Next, with reference to FIG. 3, the inspection process executed by the inspection personal computer 5 will be described. This inspection process is executed in synchronization with the line rate of the near-infrared three-wavelength line sensor camera 4.
As shown in FIG. 3, first, the inspection personal computer 5 receives imaging luminance signals Iλ1, Iλ2, and Iλ0 from the first line sensor 430, the second line sensor 440, and the third line sensor 450, that is, near infrared light. A signal representing the amount of light is acquired (step S101).
Subsequently, the inspection personal computer 5 normalizes the first light quantity Iλ1 acquired in step S101 by dividing it by the reference light quantity Iλ0. Further, the inspection personal computer 5 normalizes the second light quantity Iλ2 acquired in step S101 by dividing it by the reference light quantity Iλ0 (step S102). In this way, by normalizing with the reference light quantity Iλ0, even when the light quantity of the near-infrared light irradiation light source fluctuates, the influence exerts the same change on Iλ1, Iλ2, and Iλ0, so that the quality inspection is performed. It becomes possible to suppress the influence of. In addition, when an inspection object with a curved surface such as a granular inspection object is to be inspected in a reflective arrangement, the incident angle of the irradiated light, the light receiving angle incident on the photodetector (camera), etc. vary. Even in this case, the influence exerts the same change on Iλ1, Iλ2, and Iλ0, so that the influence on the quality inspection can be suppressed.

Subsequently, the inspection personal computer 5 uses the first light amount normalized in step S102 (hereinafter, also referred to as “normalized first light amount Iλ1 / Iλ0”) and the second light amount normalized in step S102 (hereinafter, referred to as “first normalized light amount”). By analyzing “standardized second light quantity Iλ2 / Iλ0”), a quality determination inspection of the inspection object 6 is performed (step S103). Specifically, the quality determination logic storage unit 530 of the inspection personal computer 5 is previously associated with the standardized first light amount Iλ1 / Iλ0 and the normalized second light amount Iλ2 / Iλ0 and the quality determination result. Logic is stored in advance, and based on this logic, quality determination at each inspection position of the inspection object 6 is performed. As the quality determination logic, for example, a value of a · (Iλ1 / Iλ0) + b · (Iλ2 / Iλ0) + c is determined to be a non-defective product when the value is positive, and a defective product when the value is negative (a, b, c). Is a preset constant).
Subsequently, the inspection personal computer 5 displays the inspection result of the inspection object 6 performed in Step S103 on the display 520 (Step S104).

(High speed)
In recent years, the requirements for quality inspections of foods and pharmaceuticals have become more and more severe, and it has been strongly demanded that 100% inspection is performed instead of the conventional sampling inspection. Further, not only the quality at one point of the inspection object 6 but also the need to inspect the two-dimensional quality of the inspection object 6, that is, the surface quality is increasing. Therefore, in a production line or the like, it is necessary to inspect the two-dimensional (planar) quality of the inspection object 6 being conveyed at high speed and with high accuracy.
On the other hand, in the present embodiment, the near-infrared three-wavelength line sensor camera 4 detects the amount of near-infrared light in the first wavelength region divided by the spectroscopic prism 420 with the first line sensor 430. Similarly, the amount of near-infrared light in the second wavelength range divided by the spectral prism 420 is detected by the second line sensor 440, and the amount of near-infrared light in the reference wavelength range divided by the spectral prism 420 is detected. Is detected by the third line sensor 450. Therefore, light of three types of wavelength components in the near-infrared region effective for inspection of the inspection object 6 can be detected at the same time, so that the two-dimensional quality of the inspection object 6 can be inspected at higher speed and with higher accuracy. Inspection can be performed in real time.

Incidentally, for example, in the method of inspecting the inspection object 6 based on the measurement result by FT-IR, the FT-IR is a point sensor and can measure only one spectrum of the inspection object 6. Thus, it is not possible to obtain two-dimensional quality information of the inspection object 6 being conveyed.
Further, for example, in the method of inspecting the inspection object 6 based on the measurement result of the hyperspectral camera, the hyperspectral camera is an area camera, so that two-dimensional spectral information can be obtained. Is limited by the frame rate of the area camera and cannot be applied to high-speed inspection. Hyperspectral cameras are also expensive.

Further, in the method of inspecting the inspection object 6 based on the measurement result of the near-infrared line sensor camera having a wide band, that is, a wide detection wavelength band, the two-dimensional quality information of the inspection object 6 is acquired at high speed. Although it is not possible to detect the absorption of a specific component of the inspection object 6 with high sensitivity, it is not possible to perform quality inspection with high accuracy. Although it may be possible to detect only a specific wavelength band by providing a bandpass filter or the like, the method of judging the quality of the object 6 to be inspected based only on spectrum information of a single wavelength is insufficient in accuracy. .
In the present embodiment, an example in which near-infrared light reflected by the inspection object 6 is imaged by the near-infrared three-wavelength line sensor camera 4 has been shown. However, near-infrared light transmitted through the inspection object 6 is shown. A configuration in which imaging is performed by the near-infrared three-wavelength line sensor camera 4 can also be adopted.

(Effect of this embodiment)
The invention according to this embodiment has the following effects.
(1) The inspection apparatus 1 according to the present embodiment includes a near-infrared light line illumination 3 that irradiates near-infrared light to the inspection object 6, and a near-infrared light amount Iλ1 in a predetermined first wavelength range. The first line sensor 430 to detect, the second line sensor 440 to detect the near-infrared light quantity Iλ2 in the second wavelength range different from the first wavelength range, and the change in absorption rate due to the quality of the inspection object 6 is small. A third line sensor 450 that detects the amount of light Iλ0 of near infrared light in the reference wavelength region, and is reflected by the inspection object 6 out of the near infrared light irradiated by the near infrared light line illumination 3. A near-infrared three-wavelength line sensor camera 4 that receives near-infrared light or near-infrared light that has passed through the inspection object 6 by the first line sensor 430, the second line sensor 440, and the third line sensor 450; The detected near-infrared light quantity Iλ1 in the first wavelength region and the near-infrared light in the second wavelength region An inspection for inspecting the inspected object 6 by dividing each of the quantities Iλ2 by the light amount Iλ0 of near-infrared light in the reference wavelength region, and analyzing the normalized light amounts Iλ1 / Iλ0 and Iλ2 / Iλ0 And a personal computer 5.
According to such a configuration, for example, the surface reflectance or transmittance of the inspection object 6 changes, and the amount of near-infrared light reflected or transmitted by the inspection object 6 is changed. Even if there is a change, the inspection can be suppressed based on the normalized light quantity Iλ1 / Iλ0 and the second light quantity Iλ2 / Iλ0 after the standardization, and the quality of the inspection can be suppressed. Inspection becomes possible.

(2) In the inspection apparatus 1 according to this embodiment, the near-infrared three-wavelength line sensor camera 4 receives near-infrared light reflected by the inspection object 6 or near-infrared light transmitted through the inspection object 6. A first line sensor 430, a second line sensor 440, and a first line sensor 430 are divided into a first wavelength band near infrared light, a second wavelength band near infrared light, and a reference wavelength band near infrared light, respectively. Detection is performed by a three-line sensor 450.
According to such a configuration, reflected or transmitted infrared light can be detected simultaneously with light of three types of wavelength components in the near-infrared region effective for the inspection of the inspection object 6. The dimensional quality can be inspected at high speed, and the inspection can be performed in real time.

(3) In the inspection apparatus 1 according to the present embodiment, the near-infrared light irradiation unit irradiates a linear region extending in a direction intersecting the moving direction of the inspection object with near-infrared light, The spectroscopic prism uses near-infrared light reflected by the inspection object entering the linear area or near-infrared light transmitted through the inspection object entering the linear area as a first wavelength region and a second wavelength. Each of the first light amount detection unit, the second light amount detection unit, and the third light amount detection unit is a line sensor imaging device mounted on the spectroscopic prism. is there.
According to such a configuration, the two-dimensional quality and the like of the inspection object 6 can be inspected at high speed.

(4) In the inspection apparatus 1 according to the present embodiment, the inspection object 6 is a granular object, and a plurality of granular objects are spread and conveyed on the upper surface (conveying surface) of the endless belt 210.
According to such a configuration, the incident angle of near infrared light with respect to the inspection object 6 is likely to change, and the surface reflectance of the inspection object 6 is likely to change. Therefore, the inspection apparatus 1 of this embodiment is suitable.

(5) In the inspection apparatus 1 according to this embodiment, as the first line sensor 430, the second line sensor 440, and the third line sensor 450, relatively inexpensive InGaAs line sensors can be employed.
According to such a configuration, for example, the device price can be reduced as compared with a device using an FT-IR or a hyperspectral camera.

(6) In the inspection apparatus 1 according to this embodiment, the first wavelength range is 1180 [nm] or more and 1240 [nm] or less as the center wavelength λ1, and the second wavelength range is 1400 [nm] or more and 1460 [nm]. The following is the center wavelength λ 2, and the reference wavelength region is the center wavelength λ 0 between 1560 [nm] and 1620 [nm]. Further, in the first wavelength region, the second wavelength region, and the reference wavelength region, the half-value width λw is 30 [nm] or more and 200 [nm] or less.
According to such a configuration, it can be effectively used for inspection of many organic substances. Therefore, it is not necessary to adjust the first wavelength range, the second wavelength range, and the reference wavelength range for each type of the inspection object 6, which is suitable for mass production of cameras and apparatuses.

(7) The inspection method according to the present embodiment irradiates near-infrared light to the inspection object 6, and among the irradiated near-infrared light, the near-infrared light reflected by the inspection object 6 or the inspection object A first line sensor 430 for detecting a near-infrared light that has passed through the object 6 and a predetermined amount of near-infrared light Iλ1 in a first wavelength range, a near-infrared light in a second wavelength range different from the first wavelength range A second line sensor 440 for detecting the amount of light Iλ2, and detecting a near-infrared light amount Iλ0 in the reference wavelength region in which the change in the absorptance due to the quality of the inspection object 6 is small compared to the first wavelength region and the second wavelength region. Detection is performed by the near-infrared three-wavelength line sensor camera 4 having the third line sensor 450. Then, each of the detected near-infrared light quantity Iλ1 in the first wavelength range and the near-infrared light quantity Iλ2 in the second wavelength range is divided by the near-infrared light quantity Iλ0 in the reference wavelength range for normalization. The inspection object 6 is inspected by analyzing the normalized light amounts Iλ1 / Iλ0 and Iλ2 / Iλ0.
According to such a configuration, for example, the surface reflectance or transmittance of the inspection object 6 changes, and the amount of near-infrared light reflected by the inspection object 6 or transmitted near-infrared light. Even if the amount of light changes, by performing inspection based on the standardized light amount Iλ1 / Iλ0 and the second light amount Iλ2 / Iλ0 after the standardization, the influence on the inspection can be suppressed, and high-precision quality Inspection becomes possible.

(Example)
Hereinafter, examples of the embodiment will be described with reference to FIGS. 4, 5, 6, and 7.
As an embodiment of the present invention, an example applied to the inspection of the quality of coffee beans will be described. As the apparatus configuration, the one shown in the above embodiment is adopted. Specifically, as the near-infrared light line illumination 3, a halogen line illumination having a light emitting portion length of 500 [mm] was employed. In addition, as the line sensors 430, 440 and 450, 512-pixel InGaAs line sensors were adopted.
The center wavelength λ1 of near infrared light received by the first line sensor 430 is 1210 [nm], the center wavelength λ2 of near infrared light received by the second line sensor 440 is 1410 [nm], and the third line sensor. The center wavelength λ0 of near-infrared light received by 450 is 1580 [nm]. The detection wavelength half-value width λw was 50 [nm] in all cases. The line rate was 8 [kHz]. The above λ1 corresponds to the absorption wavelength of lipid, and λ2 corresponds to the absorption wavelength of water. Further, λ0 corresponds to a wavelength having no absorption band as a component of coffee beans.
Using this apparatus, the quality of the inspection object 6 was inspected. As the inspection object 6, a mixture of 20 good coffee beans and 19 bad coffee beans was used. According to the present embodiment, as shown in FIG. 4, by using the normalized light amounts Iλ1 / Iλ0 and Iλ2 / Iλ0, it is possible to discriminate 100% between non-defective products and defective products using the discrimination line in the figure as a boundary value. I understand.

(Comparative Example 1)
In Comparative Example 1, as shown in FIG. 5, the quality of the object to be inspected 6 was inspected by using Iλ1 and Iλ2 instead of Iλ0 and Iλ2 / Iλ0 without being normalized by Iλ0. Other than that, it was the same as the example. As a result, the accuracy of discrimination between non-defective products and defective products was 72%. As a result, the method using Iλ1 and Iλ2 without being normalized by Iλ0 cannot be clearly distinguished from non-defective products and defective products due to the influence of the surface shape (reflectance) of the coffee beans, and the discrimination accuracy is low. I understand that

(Comparative Example 2)
Inspected objects (39) obtained by measuring only the light quantity Iλ1 / Iλ0 after normalization obtained by dividing the near-infrared light quantity Iλ1 obtained in the embodiment by Iλ0 and normalizing. Plotted against (FIG. 6). As a result, it was not possible to distinguish between non-defective products and defective products only with Iλ1 / Iλ0.

(Comparative Example 3)
Inspected objects (39) obtained by measuring only the light quantity Iλ2 / Iλ0 after normalization obtained by dividing the light quantity Iλ2 of the near-infrared light in the second wavelength range obtained in the example by dividing Iλ0. Plotted against (FIG. 7). As a result, it was not possible to distinguish between non-defective products and defective products only with Iλ1 / Iλ0.
From these, it can be seen that, even if normalized by Iλ0, the method using only Iλ1 / Iλ0 or only Iλ2 / Iλ0 cannot clearly distinguish between non-defective products and defective products.

DESCRIPTION OF SYMBOLS 1 Inspection apparatus 2 Inspection object conveyance part 210 Endless belt 220 Inspection area | region 3 Near-infrared light line illumination 4 Near-infrared three wavelength line sensor camera 410 Lens system 420 Spectral prism 430 1st line sensor 440 2nd line sensor 450 3rd Line sensor 5 Inspection personal computer 510 Image capture board 520 Display 530 Quality determination logic storage unit 6 Inspected object

Claims (6)

A near-infrared light irradiation unit that irradiates near-infrared light to the object to be inspected;
A first light amount detection unit that detects a light amount of near infrared light in a predetermined first wavelength region; a second light amount detection unit that detects a light amount of near infrared light in a second wavelength region different from the first wavelength region; A third light amount detection unit for detecting the amount of near infrared light in a reference wavelength range in which a change in absorption rate due to the quality of the inspection object is small compared to near infrared light in the first wavelength region and the second wavelength region; The first light amount detection unit including near infrared light reflected by the inspection object or near infrared light transmitted through the inspection object among the near infrared light irradiated by the near infrared light irradiation unit. A near-infrared light detection camera that receives light in the second light amount detection unit and the third light amount detection unit;
The third light quantity detection unit detects the light quantity of near infrared light in the first wavelength range detected by the first light quantity detection unit and the light quantity of near infrared light in the second wavelength range detected by the second light quantity detection unit, respectively. An inspection unit that inspects the object to be inspected by dividing by the amount of near-infrared light in the reference wavelength range detected in (2) and standardizing, and analyzing the amount of light after normalization ,
The first wavelength region has a central wavelength from 1180 [nm] to 1240 [nm],
The second wavelength region has a central wavelength of 1400 [nm] or more and 1460 [nm] or less,
The reference wavelength range, 1560 [nm] or more 1620 [nm] or less inspecting apparatus according to claim to Rukoto and the center wavelength. The near-infrared light detection camera uses near-infrared light reflected by the inspection object or near-infrared light transmitted through the inspection object as near-infrared light in the first wavelength range and near-infrared light in the second wavelength range. Having a spectral prism that splits light and near-infrared light in the reference wavelength range;
The first light amount detection unit receives near infrared light in the first wavelength region divided by the spectral prism and detects the light amount of the near infrared light,
The second light quantity detection unit receives near infrared light in the second wavelength region divided by the spectral prism and detects the light quantity of the near infrared light,
2. The inspection apparatus according to claim 1, wherein the third light amount detection unit receives near-infrared light in a reference wavelength region divided by the spectral prism and detects the light amount of the near-infrared light. . The near-infrared light irradiation unit irradiates near-infrared light to a linear region extending in a direction intersecting the moving direction of the inspection object,
The spectroscopic prism is configured to receive near-infrared light reflected by the inspection object entering the linear region or near-infrared light transmitted through the inspection object entering the linear region in a first wavelength range, Divided into near-infrared light in the wavelength range and reference wavelength range,
3. The inspection apparatus according to claim 2, wherein each of the first light quantity detection unit, the second light quantity detection unit, and the third light quantity detection unit is a line sensor imaging device mounted on the spectral prism. . The inspection object is a granular material,
The inspection apparatus according to claim 3, wherein the plurality of granular materials move in a planar shape in the linear region. The first wavelength range before reporting, the second wavelength region, and the reference wavelength range, any of claims 1 to 4, characterized in that the half-width of 30 [nm] or more 200 [nm] or less The inspection apparatus according to item 1. The near-infrared light is irradiated to the object to be inspected, and among the irradiated near-infrared light, near-infrared light reflected by the object to be inspected or near-infrared light transmitted through the object to be inspected is determined in advance. A first light amount detecting unit for detecting a light amount of near infrared light in a wavelength region, a second light amount detecting unit for detecting a light amount of near infrared light in a second wavelength region different from the first wavelength region, a first wavelength region, and a first wavelength region; A near-infrared light detection camera having a third light amount detection unit that detects a light amount of near-infrared light in a reference wavelength range in which a change in absorption rate due to the quality of the inspection object is small compared to near-infrared light in two wavelength regions. The first light amount detection unit, the second light amount detection unit, and the third light amount detection unit detect and detect the near-infrared light amount in the first wavelength region and the near-infrared light amount in the second wavelength region, respectively. Is an inspection method for inspecting an object to be inspected by dividing the amount by the amount of near infrared light in the reference wavelength range and analyzing the normalized amount of light ,
The first wavelength region has a central wavelength from 1180 [nm] to 1240 [nm],
The second wavelength region has a central wavelength of 1400 [nm] or more and 1460 [nm] or less,
The reference wavelength region has a center wavelength of 1560 [nm] or more and 1620 [nm] or less .

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