TWI480562B - Testing device of solar cell - Google Patents

Description

Solar cell inspection device

The present invention relates to an inspection apparatus, and more particularly to an inspection apparatus for a solar cell.

Conventionally, an inspection device for a solar battery cell is known (for example, refer to Patent Document 1).

The above Patent Document 1 discloses an appearance inspection device for a solar battery cell, comprising: an illumination device, illumination light for irradiating a wavelength of an infrared region, and a charge coupled device (CCD) camera sensitive to a near-infrared region (camera) ) (camera). The infrared light irradiated from the illumination device is transmitted through the solar cell, but when there is a defect (crack) inside the solar cell, infrared light is diffused by diffraction or diffraction around the defect. Thereby, the defective portion inside the solar battery cell is detected as the difference (shading) of the signal intensity on the captured image using the charge coupled device camera.

Further, in order to suppress the reflection of light incident on the substrate (cell), the antireflection film is formed on the surface of the solar cell. Anti-reflection The defects of the film (pin holes or foreign matter attached) also affect the characteristics of the solar cell. Therefore, in the past, not only the above internal defects but also the defects of the antireflection film (surface inspection) were detected by visual inspection. In the case of performing the visual inspection of the antireflection film, illumination light of a wavelength in the visible light region is irradiated, and reflected light reflected on the surface of the solar cell is taken. The reflection intensity of the solar cell to the normal incident light is theoretically zero with respect to the specific wavelength λ=4nd determined by the refractive index n of the antireflection film and the film thickness d. In the crystalline solar cell, an antireflection film is formed under film forming conditions of a refractive index n of about 2.0 to about 2.1 and a film thickness of d of about 80 nm, at a wavelength of a red region of 4 nd = 640 nm to 672 nm. The intensity of the reflection is minimized.

In the case of performing an appearance inspection (surface inspection) on the crystalline solar battery cell in which the antireflection film is formed, if the illumination of the unit surface is performed using the illumination light of the red region having the smallest reflection intensity, the illumination light is hardly reflected. The illumination light is reflected only in the defect (pinhole or foreign matter attached), so that the defective portion can be detected as a bright spot in the captured image.

[Prior Art Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2007-78404

However, due to various factors in the manufacturing steps of the solar cell unit The film thickness of the antireflection film is uneven. When the film thickness (d) of the antireflection film changes in comparison with the designed film thickness, the specific wavelength (λ = 4 nd) at which the reflection intensity is minimized also changes, and thus the wavelength and reflection of the illumination light for inspection The specific wavelength at which the intensity reaches a minimum causes a deviation, so that the intensity of reflection of the illumination light on the solar cell unit increases. Therefore, when the solar cell of the film thickness unevenness of the antireflection film is visually inspected, not only the reflected light of the defective portion but also the reflected light from the portion other than the defective portion is imaged, and as a result, the defective portion is captured. The bright spot is difficult to recognize in the captured image, and thus there is a problem that it is difficult to detect the defective portion of the anti-reflection film from the captured image.

The present invention has been made to solve the above problems, and an object of the present invention is to provide an inspection apparatus capable of performing defect detection with high precision even when the film thickness of the antireflection film is uneven.

In order to achieve the above object, an inspection apparatus according to an aspect of the present invention is an inspection apparatus for a solar battery cell in which an anti-reflection film is formed, and includes an illumination unit configured to illuminate illumination light with a plurality of illumination colors having mutually different wavelength regions. An imaging unit that photographs a solar battery unit using illumination light; and a control unit that obtains a captured image of the solar battery unit for each of a plurality of illumination colors, and according to a reflection intensity or resistance of the solar battery unit to illumination light of various illumination colors The film thickness of the reflective film is selected, and an image for inspection is selected from the captured images of various illumination colors, and the solar cell is inspected based on the selected captured image.

As described above, the inspection apparatus according to one aspect of the present invention includes an illumination unit configured to be capable of illuminating illumination light with a plurality of illumination colors having mutually different wavelength regions, and a control unit obtained for each of a plurality of illumination colors. a captured image of the solar battery cell, and an image for inspection is selected from the captured images of the various illumination colors according to the reflection intensity of the illumination light of the various illumination colors or the film thickness of the anti-reflection film of the solar battery cell, and The solar cell is inspected based on the selected captured image, whereby even in the case where the film thickness of the anti-reflection film is uneven, it is possible to use a captured image of illumination light of a plurality of colors having different wavelength regions. The image is selected as an image captured by illumination light of a wavelength region (illumination color) corresponding to the reflection intensity of the solar cell or the film thickness of the anti-reflection film. Therefore, it is possible to select an image to be imaged by using illumination light that can accurately detect the illumination color (wavelength) of the defective portion, and to perform an appearance inspection. Therefore, even when the film thickness of the anti-reflection film is uneven, the height can be high. Defect detection is performed accurately.

In the inspection apparatus according to the above aspect, preferably, the control unit is configured to select a captured image based on signal intensities of captured images of various illumination colors reflecting reflection intensities from a plurality of captured images of various illumination colors. The captured image is selected based on the film thickness of the anti-reflection film. According to this configuration, the reflection intensity of the solar cell unit for each wavelength changes due to the unevenness of the film thickness, and as a result, the signal intensity (shading) of the captured image taken by the illumination light of each color differs. Therefore, it is possible to easily select a captured image of the illumination color capable of detecting the defective portion with high accuracy based on the signal intensity of the captured image. In addition, the solar cell unit has a strong reflection as described above. Since the minimum wavelength is determined by the film thickness of the antireflection film having a predetermined refractive index, it is possible to easily select a captured image of the illumination color capable of detecting the defective portion with high accuracy based on the film thickness of the antireflection film.

In this case, it is preferred that the plurality of illumination colors include at least red and blue. When the antireflection film is formed under the film formation conditions (n=about 2.0) of about 80 nm as described above, the lower limit (allowable range) of the film thickness range to be considered can be about 60 nm. In this case, the reflection intensity of red light is minimized when the film thickness is relatively thick at 80 nm, and the reflection intensity of blue light of λ = 480 nm to 504 nm when the film thickness is thin and is about 60 nm and uneven. Become smaller. Therefore, according to the present invention, at least the red and blue colors are included in the illumination color, and the image of the red light and the film thickness can be at least from the case where the film thickness is thick, depending on the range of the film thickness unevenness which may actually occur. In the captured image of the blue light in the case of the case, a captured image suitable for the detection of the defective portion is selected.

In the configuration in which the plurality of illumination colors include at least red and blue, it is preferable that the control unit is configured to select a captured image having a relatively low signal intensity from a plurality of captured images of various illumination colors, or to select and anti-reflection. A captured image of the illumination color corresponding to the film thickness of the film. According to this configuration, the captured image having a relatively low signal intensity is a captured image of an illumination color (wavelength) of a specific wavelength whose reflection intensity is small, and therefore, it is possible to easily select a defective portion by selecting the image. The detected camera image. Further, if the film thickness of the anti-reflection film is correlated with the illumination color of the captured image, it is possible to easily select an appropriate image by selecting an image of the illumination color corresponding to the film thickness. A captured image of the detection of the trap.

In the inspection apparatus according to the above aspect, preferably, the control unit is configured to perform defect inspection on the anti-reflection film formed on the solar battery cell using a determination threshold corresponding to the illumination color of the selected captured image. According to this configuration, the unevenness of the signal intensity in the captured image, the strength of the signal intensity of the bright spot appearing as the defective portion, the level of the average signal intensity, and the like are changed according to the illumination color, thereby using The determination threshold corresponding to the illumination color can perform defect detection with high precision regardless of the case of selecting a captured image of the illumination color.

In the inspection apparatus according to the above aspect, preferably, the control unit is configured to obtain a part image of each illumination color for each of the plurality of solar battery cells, and select for each part of the solar battery cell for inspection. The part image is checked and based on the selected part image. According to this configuration, even when the film thickness of the anti-reflection film on each portion of the solar cell unit is uneven, a captured image of an illumination color suitable for defect detection can be selected for each portion. Defect detection is performed, so defect detection can be performed with higher precision. In particular, if the size of the solar cell unit becomes large, the film thickness of the anti-reflection film at each portion is apt to be uneven, so that the present invention is suitable for inspection of a large-sized solar cell.

In the configuration in which the control unit selects a captured image having a relatively low signal intensity or an image of an illumination color corresponding to the film thickness of the antireflection film, it is preferable that the control unit is configured to be a plurality of captured images. The average or median of the signal intensities is compared, and a captured image of the illumination color having the lowest average value or the median value is selected. If this side In the configuration, it is not necessary to calculate the film thickness of the anti-reflection film, and it is possible to easily select a captured image suitable for defect detection by merely comparing the average value (or median value) of the signal intensities of the plurality of captured images of different illumination colors.

In the configuration in which the control unit selects a captured image having a relatively low signal intensity or an image of an illumination color corresponding to the film thickness of the antireflection film, it is preferable that the control unit is configured to pass the illumination light wavelength and the solar cell. Fitting the reflection intensity of the unit with the theoretical curve, and obtaining the film thickness of the anti-reflection film corresponding to the signal intensity of the captured image of the various illumination colors, and selecting and including the film thickness of the obtained anti-reflection film A captured image of an illumination color corresponding to a predetermined film thickness range. According to this configuration, the film thickness of the antireflection film can be obtained with high precision by fitting the theoretical curve calculated for each film thickness with the curve (actual measurement value) of the signal intensity obtained from each captured image. Further, by setting the film thickness range and the illumination color suitable for defect detection in the film thickness range in advance, a captured image suitable for defect detection can be selected in accordance with the obtained film thickness.

In the configuration in which the control unit selects a captured image having a relatively low signal intensity or an image of an illumination color corresponding to the film thickness of the antireflection film, it is preferable that the control unit is configured to use reflection of various illumination colors. A reference data (strength) in which the intensity is correlated with the film thickness of the antireflection film, a film thickness of the antireflection film corresponding to the signal intensity of the captured image is obtained, and a predetermined thickness of the film thickness of the obtained antireflection film is selected. A captured image of the illumination color corresponding to the film thickness range. If constructed in this way, a base that correlates the reflection intensity of various illumination colors with the film thickness of the anti-reflection film is created in advance. The quasi-data can easily obtain the film thickness of the anti-reflection film from the measured values of the signal intensities obtained from the respective captured images. Further, by setting the film thickness range and the illumination color suitable for the defect detection in the film thickness range in advance, it is possible to easily select a captured image suitable for defect detection from the obtained film thickness.

In the inspection apparatus of the above aspect, it is preferable that the plurality of illumination colors include red, blue, and green. As described above, in the antireflection film having a refractive index n of about 2.0, the reflection intensity of red light is minimized when the film thickness is 80 nm, and the reflection intensity of blue light becomes small when the film thickness is about 60 nm. When the film thickness is about 70 nm, the reflection intensity of green light is small. Therefore, according to the present invention, by including red, blue, and green colors in the illumination color, it is possible to select a captured image suitable for detection of the defective portion in accordance with the range of film thickness unevenness that may actually occur. Further, since the film thickness of the anti-reflection film can be specified by the signal intensity ratio of the three primary colors of red, blue, and green, it is possible to easily select a captured image suitable for detection of the defective portion.

In the inspection apparatus of the above aspect, it is preferable that the solar cell unit comprises a polycrystalline semiconductor, and the antireflection film is a silicon nitride film. In the polycrystalline solar cell, the crystal grain boundary is clearly displayed in the captured image of the illumination color different from the wavelength (illumination color) at which the reflection intensity is the smallest, and the defective portion is submerged in the grain boundary image and cannot be detected. Further, in the polycrystalline solar cell, a tantalum nitride film is often used as an antireflection film. The inspection apparatus of the present invention can be preferably used for visual inspection of a polycrystalline solar cell in which a tantalum nitride film is formed.

According to the present invention, as described above, the defect detection can be performed with high precision even when the film thickness of the antireflection film is uneven.

1‧‧‧Solar battery unit

2‧‧‧Semiconductor substrate (polycrystalline semiconductor)

3‧‧‧Anti-reflective film

10‧‧‧Lighting Department

11‧‧‧Light source

11a‧‧‧Red light source

11b‧‧‧Green light source

11c‧‧‧Blue light source

12‧‧‧ Keeping Department

13‧‧‧ openings

20‧‧‧Photography Department

21‧‧‧ lens

30, 230‧‧‧Control Department

31‧‧‧ Storage Department

40‧‧‧ frame

60, 60a, 60b, 60c‧‧‧ camera images

70‧‧‧Defects

80‧‧‧ part image

100, 200‧‧‧ visual inspection device (inspection device)

110‧‧‧Transporter

D‧‧‧ film thickness

Th‧‧‧ decision threshold

Cf‧‧‧ reflectance-wavelength curve

Ac‧‧‧ Approximate curve

Average (or median) of Ia‧‧‧ signal strength

Xa‧‧‧ position of the peak of the signal strength greater than the decision threshold

X1, X2, X3, X4, Y1, Y2, Y3, Y4‧‧‧ parts

S1~S11, S21~S34‧‧‧ steps

1 is a schematic view showing an overall configuration of an appearance inspection device according to a first embodiment and a second embodiment of the present invention.

FIG. 2 is a perspective view schematically showing a configuration of an imaging unit and an illumination unit of the visual inspection device according to the first embodiment and the second embodiment of the present invention.

3(a), 3(b), and 3(c) are diagrams showing an example of a captured image of the imaging unit.

4 is a view showing a reflectance (reflection intensity)-wavelength curve for explaining a second selection method of a captured image.

FIG. 5 is a view showing a reflectance (reflection intensity)-film thickness curve for explaining a third method of selecting a captured image.

(a) and (b) of FIG. 6 are views for explaining defect inspection processing of the visual inspection device according to the first embodiment and the second embodiment of the present invention.

FIG. 7 is a flowchart for explaining a control process of the control unit at the time of inspection of the visual inspection device according to the first embodiment of the present invention.

FIG. 8 is a view showing an example of a part image used for the inspection process of the visual inspection device according to the second embodiment of the present invention.

FIG. 9 is a flowchart for explaining a control process of the control unit during inspection of the visual inspection device according to the second embodiment of the present invention.

Hereinafter, an embodiment in which the present invention is embodied will be described based on the drawings.

(First embodiment)

First, the overall configuration of the visual inspection device 100 according to the first embodiment of the present invention will be described with reference to Fig. 1 . In the first embodiment, an example in which the present invention is applied to an appearance inspection device 100 that inspects a defect (a surface defect of a solar cell) of an anti-reflection film formed on a surface of a solar cell is described.

The visual inspection device 100 according to the first embodiment is an inspection device that is installed on a production line and inspected in line in the production process of the solar battery cell 1. The solar battery cell 1 includes a semiconductor substrate 2 (hereinafter referred to as a substrate 2), and an anti-reflection film 3 formed on a surface (light receiving surface) of the substrate 2. In addition, in FIG. 1, for convenience, the thickness of the solar cell unit 1 is enlarged, and each layer (substrate 2 and anti-reflection film 3) is shown typically. The anti-reflection film 3 is a dielectric (insulator) film that does not substantially absorb light in the visible light region, and a material having a desired refractive index and capable of being formed with a desired film thickness is used. In the first embodiment, the substrate 2 is, for example, a polycrystalline germanium semiconductor substrate, and the antireflection film 3 is a SiN film (refractive index n = about 2.0 to 2.1). Further, a surface electrode (not shown) having a predetermined pattern is formed on the surface of the solar cell 1. The defect inspection by the visual inspection device 100 against the reflective film may be performed at any step before and after the step of forming the surface electrode.

The visual inspection device 100 mainly includes an illumination unit 10 that illuminates the solar battery unit 1 with illumination light, and an imaging unit 20 that uses illumination light pairs that are illuminated by the illumination unit 10. The solar battery unit 1 performs imaging; and the control unit 30 performs defect inspection processing based on the captured image. Each of the portions is housed in a casing 40 for shielding light from the outside when inspecting the solar battery cells 1.

As shown in FIG. 2, the illumination unit 10 is provided so as to be located above the solar battery cell 1 disposed at the inspection position. The illuminating unit 10 includes a plurality of light sources 11 (11a to 11c) and a dome-shaped holding portion 12 that holds a plurality of light sources 11 in a circumferential shape (annular shape) at the lower end portion of the inner wall.

Each of the light sources 11 includes, for example, a light emitting diode (LED), and the light irradiation direction is directed upward (in the direction of the inner wall of the holding portion 12). The plurality of light sources 11 include light-emitting diodes of three kinds of illumination colors of a red (R) light source 11a, a green (green) light source 11b, and a blue (blue, B) light source 11c, so as to be pressed in the circumferential direction. This order of repetition is arranged side by side. Each of the illumination colors is, for example, a center wavelength of about 627 nm (red), about 530 nm (green), and about 470 nm (blue). As shown in FIG. 1, each light source 11 is controlled by the control unit 30 in accordance with various illumination colors. Thereby, the illumination unit 10 is configured to be able to illuminate illumination light of a plurality of illumination colors (R, G, and B) having mutually different wavelength regions.

As shown in FIG. 2, a diffusing reflection plate (not shown) is provided on the inner wall of the arch-shaped holding portion 12. The light from the light source 11 irradiated toward the inner wall is diffused and reflected on the inner wall of the holding portion 12, and is irradiated as uniform illumination light to the entire surface of the solar battery cell 1 disposed at the lower position. Further, an opening portion 13 for guiding light to the imaging unit 20 is formed in the upper portion of the holding portion 12.

As shown in FIGS. 1 and 2 , the imaging unit 20 is disposed above the illumination unit 10 and receives the reflected light from the solar cell 1 of the opening 13 and the lens 21 of the holding unit 12 to capture the solar cell 1 . . The imaging unit 20 is constituted by, for example, a charge-coupled device camera of monochrome 5 million pixels (about 2000 × 2500 pixels). Further, the entire solar battery cell 1 is imaged using, for example, a lens 21 having a square shape of about 156 mm and a focal length of about 25 mm.

The control unit 30 performs control processing on the entire visual inspection device 100 including the illumination unit 10 and the imaging unit 20. The control unit 30 is provided with a storage unit 31 that stores the captured image 60 of the imaging unit 20 (see FIGS. 3( a ), 3 ( b ), and 3 ( c )), or for a solar cell. Various materials of the inspection of the unit 1 (threshold value Th or determination condition, etc., which will be described later). Further, the control unit 30 is configured to be communicable with a conveyor 110 incorporated in the production line of the solar battery unit 1 and based on the fact that the solar battery unit 1 from the conveyor 110 has been positioned at a predetermined inspection position. The inspection process is performed by communication. In the first embodiment, the control unit 30 obtains the captured image 60 of the solar battery cell 1 for each of three types of (R, G, B) illumination colors (see FIG. 3(a), FIG. 3(b), and FIG. 3(c)), and based on the reflection intensity of the illumination light of each color of the solar battery cell 1 or the film thickness d of the anti-reflection film 3, an image for inspection is selected from the image pickup images 60 of the various illumination colors. Then, the control unit 30 is configured to perform surface defect inspection on the solar battery cell 1 based on the selected captured image 60. Surface defect inspection of solar battery unit 1, Specifically, the defect portion 70 of the anti-reflection film 3 on the cell surface shown in FIG. 1 is inspected, and the defect portion 70 of the anti-reflection film 3 is, for example, a pinhole formed on the anti-reflection film 3 or attached to the anti-reflection film 3 Foreign matter on the top.

Next, details of the inspection process of the solar battery cell 1 will be described with reference to FIGS. 3(a), 3(b), 3(c) to 6(a), and 6(b).

In the solar battery cell 1 in which the anti-reflection film 3 is formed, according to the thin film interference theory, the reflection intensity of light having a specific wavelength λ = 4 nd corresponding to the refractive index n and the film thickness d of the anti-reflection film 3 is remarkably lowered (in theory reflection) The intensity becomes 0). In the first embodiment, the film thickness d (design) of the anti-reflection film 3 is set to be about 80 nm. In this case, for the solar battery cell 1 in which the antireflection film 3 (n = 2.0 to 2.1) having d = about 80 nm is formed, reflection of red light in a wavelength range of a specific wavelength λ (= 4 nd) = 640 nm to 672 nm The strength is lowered, and as a result, it appears to have a blue hue in appearance.

When the solar battery cell 1 is imaged using red (about 627 nm) illumination light, the captured image 60 (60a) shown in Fig. 3 (a) can be obtained. That is, since the reflection intensity of the red light is extremely small, the signal intensity of substantially the entire solar battery cell 1 is low, and the image becomes a dark image. In this case, when there is a pinhole or a defect such as foreign matter adhering to the anti-reflection film 3, the defective portion 70 (shown by white dots in FIGS. 3(a), 3(b), and 3(c)) The upper reflection intensity does not decrease, and thus the defective portion 70 appears as a region (bright spot) having a high signal intensity in the captured image 60a. When the defect inspection is performed using the captured image 60a shown in FIG. 3(a), Since the difference between the bright spot of the trap portion 70 and the signal intensity of the portion other than the defective portion 70 is extremely large, the defect inspection can be performed with high precision.

However, if the film thickness d of the anti-reflection film 3 of each unit is uneven due to various factors in the production steps of the solar cell 1, the specific wavelength λ at which the reflection intensity is lowered also changes in accordance with the film thickness d. For example, in the case where the film thickness d is 60 nm, the reflection intensity of the blue light in the wavelength range of the specific wavelength λ = 480 nm to 504 nm is lowered. In this case, if the same red (about 627 nm) illumination light is used for photographing, the reflection intensity of the red light is not lowered, so that the substrate as the anti-reflection film 3 is clearly exhibited as shown in FIG. 3(c). A bright captured image 60 (60c) of the crystal grain boundary of the substrate 2. In the captured image 60c, the bright spot of the defective portion 70 is difficult to recognize in the grain boundary image, and the difference in signal intensity is unclear, so that it is difficult to recognize the defective portion 70. Further, when the green wavelength region which is extremely close to the red wavelength is the specific wavelength λ (4 nd = 530 nm or so), the captured image using the red light becomes the captured image 60a and the image shown in FIG. 3(b). A captured image 60 (60b) of the signal intensity of the intermediate degree of the image 60c. As described above, since the specific wavelength λ changes due to the unevenness of the film thickness d, the defect inspection cannot be performed with high precision for the captured image 60 of only a single red light.

Thus, in the first embodiment, the control unit 30 obtains the captured image 60 of the solar battery cell 1 for each of a plurality of (R, G, B) illumination colors, and according to the illumination light of each color of the solar battery cell 1 The reflection intensity or the film thickness d of the anti-reflection film 3 is selected from the images of the various illumination colors of the captured image 60 for inspection. The method of selecting the captured image 60 may be performed by an appropriate selection method from the first to third selection methods described below.

The first selection method is a method of selecting the captured image 60 based on the signal intensity of the captured image 60 of various illumination colors reflecting the reflection intensity. The control unit 30 selects the captured image 60 having a relatively low signal intensity from the three (R, G, B) captured images 60 of various illumination colors. More specifically, the control unit 30 compares the average value or the median value of the signal intensities of the three captured images 60, and selects the captured image 60 of the illumination color having the lowest average value or the median value. Thus, as described above, in the case of the specific wavelength λ=640 nm to 672 nm (film thickness d=80 nm), the captured image of the red light becomes the captured image 60a of FIG. 3(a), and the green light is imaged. The image becomes the captured image 60b of FIG. 3(b), and the captured image of the blue light becomes the captured image 60c as shown in FIG. 3(c). The image having the lowest average value (median value) of the signal intensity becomes the captured image 60 of the red light, and thus the captured image 60 (60a) of the red light suitable for the defect inspection is selected. In addition, in the case of a specific wavelength λ=480 nm to 504 nm (film thickness d=60 nm), the captured image of the blue light is imaged as the captured image 60a of FIG. 3(a), so the image of the blue light is selected. The image with the lowest average value (median value) of the signal strength.

The second selection method and the third selection method are methods in which the captured image 60 is selected based on the film thickness d of the anti-reflection film 3. As described above, if the refractive index n is fixed, the specific wavelength λ at which the reflection intensity of the solar battery cell 1 is lowered depends on the film thickness d of the anti-reflection film 3. Therefore, if the film thickness d can be obtained, it can be decided The fixed wavelength λ. Further, if the captured image 60 of the illumination light closest to the wavelength (illumination color) of the specific wavelength λ is selected from the three captured images 60, the captured image 60a suitable for the defect inspection can be selected.

In the second selection method, the control unit 30 obtains the film thickness d of the anti-reflection film 3 by fitting the wavelength of the illumination light and the reflection intensity of the solar cell 1 to the theoretical curve. The reflection intensity is based on the Fresnel formula considering the interference condition and is expressed by a function of various variables such as reflectance = f (λ, θ, n, k, d, nsi, ksi). Here, λ, θ, n, k, d, nsi, and ksi are the wavelength of the illumination light, the incident angle, the refractive index of the antireflection film, the extinction coefficient of the antireflection film, the film thickness, and the ruthenium substrate. Refractive index and extinction coefficient. N, k, nsi, and ksi are known from the physical properties of the antireflection film 3 and the substrate 2, and the reflectance (reflection intensity) with a variable wavelength can be obtained by setting the film thickness d and the incident angle θ. When this setting is made for each film thickness d, the reflectance (reflection intensity)-wavelength curve Cf (d = d1, d2, d3, ...) at each film thickness d shown in Fig. 4 can be obtained.

The control unit 30 plots the reflection intensity at each wavelength (that is, the signal intensity of the captured image 60) on the captured image 60 of the three colors, and draws an approximate curve of three points obtained by the connection. Curve fitting with the reflectance-wavelength curve Cf at each film thickness d. As a result, for example, the film thickness of the reflectance-wavelength curve Cf in which the approximate curve Ac is most uniform can be determined as the film thickness d of the anti-reflection film 3 by the least square method. Further, the correspondence relationship between the film thickness range and the illumination color is set in advance in the storage unit 31 of the control unit 30 (for example, if d=70 nm to 90 nm) Red illumination is performed, and if it is 60 nm to 65 nm, blue illumination is performed, and if it is 65 nm to 70 nm, green illumination is performed. When the film thickness d is obtained, the image pickup image 60 of the illumination color corresponding to the film thickness range to which the obtained film thickness d belongs can be selected based on the correspondence relationship between the film thickness range set in advance and the illumination color.

In the third selection method, the control unit 30 obtains the film thickness d of the anti-reflection film 3 using reference data (standard curve) in which the reflection intensity of various illumination colors is correlated with the film thickness d of the anti-reflection film 3. In the same theoretical calculation as in the second selection method, by making the wavelength λ constant and taking the film thickness d into a variable, the wavelength λ (627 nm (red), 530 nm (green) of various illumination colors shown in FIG. 5 can be calculated. And reflectance (reflection intensity) at 470 nm (blue) - film thickness curve Cs (R, G, B). When the signal intensity of the captured image 60 of the three colors is applied as the value of the corresponding reflectance of each of the reflectance-film thickness curves Cs, the film thickness d can be obtained. Alternatively, in FIG. 5, the blue reflectance-film thickness curve Cs(B) is linear in the range of about 60 nm to about 100 nm, so that the corresponding film can be obtained from the signal intensity of the captured image 60 of the blue light. Thick d. After the film thickness d is obtained, the control unit 30 selects the captured image 60 based on the correspondence relationship between the film thickness range set in the storage unit 31 and the illumination color, similarly to the second selection method described above.

The control unit 30 selects an image for inspection by using any of the above-described first to third selection methods. Thereby, even when the film thickness d is uneven, by selecting the captured image 60 corresponding to the film thickness d of the anti-reflection film 3 on the solar battery cell 1, the defect and the defect can be used as shown in Fig. 3(a). Highlights of department 70 The image is captured by the captured image 60a having a large difference in signal intensity.

Next, an example of defect inspection using the selected captured image 60 (60a) will be described with reference to FIGS. 6(a) and 6(b).

In the captured image 60a shown in Fig. 6(a), the horizontal direction is the X-axis and the vertical direction is the Y-axis, and the signal intensity distribution in the X-axis direction on the Y coordinate Ya is shown in the solid line of Fig. 6(b). . In addition, FIG. 6(a) is a cross-sectional view showing the Ya coordinate of the solar battery cell 1, and shows a pinhole of the anti-reflection film 3 as an example of the defective portion 70. As shown in FIG. 6(b), in the case where the defective portion 70 is present, a large peak of signal intensity is formed on the X coordinate Xa. On the other hand, in the region other than the defective portion 70, although the signal intensity slightly changes, the overall low signal intensity is substantially constant. Therefore, the control unit 30 determines the position (Xa) as the defect portion 70, and the average of the signal intensity of the position (Xa) with respect to the entire captured image 60 (60a), in consideration of the determination threshold value Th in consideration of the slight fluctuation amount of the signal intensity. The value (or the median) Ia has a peak of the signal strength larger than the determination threshold Th.

The surface defect inspection is performed on the entire solar battery cell 1 by detecting the defective portion 70 throughout the Y coordinate. In the defect inspection, not only the number of defective portions 70 in the captured image 60 (60a) but also the size (area) of each defective portion 70 is obtained based on the set of the primitive regions whose signal intensity is larger than the determination threshold Th.

Further, in the first embodiment, the determination threshold value Th is individually set in accordance with the illumination color of the selected captured image 60. That is, depending on the lighting color, there are also A case where the signal intensity tends to become high and the deviation is relatively large (refer to the broken line of FIG. 6(b)). Therefore, an appropriate determination threshold Th corresponding to the illumination color is set in consideration of the signal intensity or the magnitude of the deviation of the various illumination colors. Further, the algorithm itself of the defect inspection process may be changed for various illumination colors.

Next, the control process of the control unit 30 at the time of inspection of the visual inspection device 100 according to the first embodiment will be described with reference to FIGS. 1 , 6 ( a ), 6 ( b ), and 7 .

First, in step S1, the solar battery unit 1 as the inspection object is carried in from the upstream step of the production line by the conveyor 110 (see FIG. 1). When receiving the communication in the case where the solar battery unit 1 from the conveyor 110 is placed at a predetermined inspection position, the control unit 30 starts the inspection processing operation.

In step S2, a captured image using illumination light of red (R) is obtained. That is, the control unit 30 turns on the red (R) light source 11a in the illumination unit 10, and images the solar battery unit 1 by the imaging unit 20. After the shooting is performed, the red (R) light source 11a is turned off.

Similarly, in step S3, a captured image using illumination light of green (G) is obtained. The control unit 30 sequentially performs opening of the green (G) light source 11b, imaging, and closing of the green (G) light source 11b. Then, in step S4, a captured image using illumination light of blue (B) is obtained. The control unit 30 sequentially performs opening of the blue (B) light source 11c, imaging, and closing of the blue (B) light source 11c. Through the steps S2 to S4, three captured images 60 each using illumination light of three colors are obtained. In addition, the order of imaging of the captured image 60 of each color (the order of steps S2 to S4) is arbitrary.

In step S5, the control unit 30 selects from the captured images 60 of red (R), green (G), and blue (B) for inspection using any of the first to third selection methods described above. Camera image 60 (60a).

In step S6, the control unit 30 reads out and selects the determination threshold value Th corresponding to the selected illumination color from the storage unit 31 (the determination threshold value Th and the inspection algorithm when the inspection algorithm is also changed according to the illumination color) .

Then, in step S7, the control unit 30 performs the defect inspection processing shown in FIGS. 6(a) and 6(b) over the entire captured image 60 (60a). Thereby, the control unit 30 obtains the number of detected defective portions 70, the size (area) of each defective portion 70, and the like.

Next, in step S8, it is judged whether or not the inspection result meets the predetermined determination condition for discriminating the defective product or the defective product.

One or more determination conditions may also be used in the determination. For example, it is determined whether or not the number of defective portions 70 is equal to or greater than a set threshold value (N1), and is determined to be unqualified when N1 or more, and "determine whether or not the total area of the defective portion 70 is determined. N2% or more of the entire solar battery cell 1 is determined to be unacceptable when it is N2% or more, and "N3 (for example, 10) of defective portions 70 having an area P1 (for example, 1 mm2) or more for each defective portion 70 In the above case, the large defective portion 70 having an area P2 (for example, 5 mm 2 ) or more is N 4 (for example, 1) In the case of the above, it is determined that the test is unsatisfactory. The control unit 30 uses one or more of the above determination conditions in combination to determine whether or not the pass is acceptable.

When the result of the determination is that the determination condition is satisfied (the condition that is determined to be unsatisfactory), the control unit 30 proceeds to step S9 and determines that the solar battery cell 1 as the inspection object is defective. When the result of the determination is that the determination condition is not satisfied (the condition that the determination is unsatisfactory), the control unit 30 proceeds to step S10, and determines that the solar battery cell 1 as the inspection object is a good product.

Thereafter, the process proceeds to step S11, and the control unit 30 determines whether or not the inspection of all the units of the predetermined inspection (predetermined production) has ended. When the inspection of all the units has not ended, the processing returns to step S1 to perform the inspection of the next solar battery unit 1. . When the control unit 30 determines that the inspection of all the units has been completed, the inspection is ended.

In the first embodiment, as described above, the illumination unit 10 is provided so that the illumination light (R, G, B) of three colors having mutually different wavelength regions can be irradiated; and the control unit 30 can be configured. The captured image 60 of the solar battery cell 1 is obtained for various illumination colors, and an image from various illumination colors is obtained according to the reflection intensity of the illumination light of the various illumination colors of the solar battery cell 1 or the film thickness d of the anti-reflection film 3. The image for inspection is selected in 60, and the solar battery cell 1 is inspected based on the selected captured image 60 (60a), thereby even when the film thickness d of the anti-reflection film 3 is uneven. It is also possible to select illumination of a wavelength region (illumination color) corresponding to the reflection intensity of the solar battery cell 1 or the film thickness d of the anti-reflection film 3 from the captured image 60 captured using illumination light of three colors having different wavelength regions. Light The image 60a is captured. Therefore, it is possible to select an image of the image captured by the illumination light that can accurately detect the illumination color of the defect portion 70 (the illumination color of the wavelength close to the specific wavelength λ), and perform the visual inspection. Therefore, even in the anti-reflection film 3 When the film thickness d is uneven, the defect detection can be performed with high precision.

In the first embodiment, as described above, the control unit 30 is configured such that the captured image 60a is selected based on the signal intensity of the captured image 60 reflecting the reflection intensity from the three captured images 60 of the various illumination colors. The captured image 60a is selected based on the film thickness d of the anti-reflection film 3. Thereby, the reflection intensity of the solar battery cell 1 for each wavelength changes due to the unevenness of the film thickness d, and as a result, the signal intensity (shading) of the captured image 60 captured by the illumination light of each color is different. This makes it possible to easily select the captured image 60a capable of detecting the illumination color of the defective portion 70 with high precision based on the signal intensity of the captured image 60. Further, the specific wavelength λ at which the reflection intensity of the solar battery cell 1 is the smallest is determined by the film thickness d of the anti-reflection film 3 having the predetermined refractive index n, so that the film thickness d of the anti-reflection film 3 can be easily selected. The captured image 60a of the illumination color of the defective portion 70 is detected with high precision.

In the first embodiment, the control unit 30 is configured as described above, that is, the anti-reflection film 3 formed on the solar battery cell 1 is determined using the determination threshold Th corresponding to the illumination color of the selected captured image 60. Perform a defect check. Thereby, the unevenness of the signal intensity in the captured image 60, the intensity of the signal intensity of the bright spot appearing as the defective portion 70, the level of the average signal intensity, and the like are changed according to the illumination color, thereby being able to correspond to the illumination color by using The determination threshold Th is performed with high precision Trap detection.

In the first embodiment, the control unit 30 is configured such that the average or median value of the signal intensities of the plurality of captured images 60 is compared as described in the first selection method of the captured image 60. And select the captured image 60 of the illumination color having the lowest average value or the median value. According to this configuration, it is not necessary to calculate the film thickness d of the anti-reflection film 3, and it is easy to select an appropriate value by comparing only the average value (or median value) of the signal intensities of the three captured images 60 having different illumination colors. The captured image 60 of the defect detection.

In the first embodiment, the control unit 30 is configured such that the anti-reflection film 3 is obtained by fitting with the reflectance-wavelength curve Cf as described in the second selection method of the captured image 60. The film thickness d is selected, and an image of the illumination color 60 corresponding to the predetermined film thickness range including the obtained film thickness d is selected. According to this configuration, anti-reflection can be obtained with high precision by fitting the reflectance-wavelength curve Cf calculated for each film thickness with the curve (measured value) of the signal intensity obtained from each of the captured images 60. The film thickness d of the film 3.

In the first embodiment, the control unit 30 is configured to associate the reflection intensity of various illumination colors with the film thickness d of the anti-reflection film 3 as described in the third selection method of the captured image 60. The reflectance (reflection intensity)-film thickness curve Cs is obtained to obtain the film thickness d of the anti-reflection film 3, and the image of the image 60 of the illumination color corresponding to the predetermined film thickness range including the obtained film thickness d is selected. If constructed in this way, the reflectance (reflection intensity) of various illumination colors can be created in advance - the film The thick curve Cs (R, G, B), and the film thickness d of the anti-reflection film 3 is easily obtained from the measured values of the signal intensities obtained from the respective captured images 60.

In the first embodiment, as described above, the plurality of illumination colors include red (R), blue (B), and green (G). As described above, with respect to the antireflection film 3 having a refractive index n of about 2.0, the reflection intensity of the red light (R) is minimized at a film thickness d = 80 nm, and blue light (B) is obtained at d = 60 nm or so. The reflection intensity becomes small, and the reflection intensity of the green light (G) becomes small at around d=70 nm. Therefore, by including the red, blue, and green colors in the illumination color, the captured image 60 suitable for the detection of the defective portion 70 can be selected in accordance with the range of film thickness unevenness that may actually occur.

In the first embodiment, as described above, the solar battery cell 1 includes a polycrystalline semiconductor, and the antireflection film 3 is a tantalum nitride film (SiN). In the polycrystalline solar cell 1 , in the captured image 60 of the illumination color different from the specific wavelength λ at which the reflection intensity is the smallest, the crystal grain boundary is clearly revealed as shown in FIG. 3( c ), and the defect portion is clearly formed. 70 is submerged in the grain boundary image and cannot be detected. Further, a tantalum nitride film (SiN) is often used as the antireflection film 3 for the polycrystalline solar cell 1, and the visual inspection device 100 of the first embodiment can be preferably used for forming a tantalum nitride film (SiN). The visual inspection of the polycrystalline solar cell 1 as the antireflection film 3.

(Second embodiment)

Next, an appearance inspection device 200 according to a second embodiment of the present invention will be described with reference to FIGS. 1 , 6( a ), and 6 ( b ) to 9 . In the second embodiment, an example configured as follows, in addition to the configuration of the first embodiment described above, A defect check is also performed for each partial image of the captured image. In the second embodiment, the device configuration is the same as that of the visual inspection device 100 according to the first embodiment described above, and thus the description thereof is omitted. In addition, the visual inspection device 200 is an example of the "inspection device" of the present invention.

As shown in FIG. 8, the control unit 230 (see FIG. 1) of the visual inspection device 200 (see FIG. 1) of the second embodiment obtains a part image 80 of various illumination colors for each of the plurality of locations of the solar battery cell 1. Further, the control unit 230 is configured to select a part image 80 for inspection for each part of the solar battery cell 1 and perform inspection based on the selected part image 80.

Specifically, the control unit 230 divides the obtained captured image 60 into a plurality of part images 80, and individually selects an image for inspection for each part image 80. In the example of FIG. 8, an example is shown in which, for the captured image 60 (example 60c), a total of 16 determinants which are divided into four parts (X1 to X4 and Y1 to Y4) in the X-axis and the Y-axis are obtained. Part of the image 80. Thereby, the part image 80 of three colors of R, G, and B is obtained for each part.

The selection method of the part image 80 is the same as that of the first embodiment described above, and the control unit 230 selects the part image 80 for inspection for each part by any one of the first selection method to the third selection method. Thus, for example, even when the size of the solar battery cell 1 is large and the film thickness d of the anti-reflection film 3 at each portion is not uniform, an appropriate portion image 80 can be selected for each portion.

Other configurations of the visual inspection device 200 according to the second embodiment and the first The implementation is the same.

Next, the control process of the control unit 230 at the time of inspection of the visual inspection device 200 according to the second embodiment will be described with reference to FIG. 7 to FIG.

Steps S21 to S24 are the same as steps S1 to S4 of Fig. 7 . In step S25, the control unit 230 divides the obtained captured images 60 of the three colors (R, G, B) into a plurality of (16 parts in the example of FIG. 8) part images 80.

In step S26, the control unit 230 selects the part where the inspection is performed. For example, in FIG. 8, the X1Y1 portion is inspected in the X direction (to X4Y1), and the process or the like is sequentially performed row by row (Y coordinate), and the portion to be inspected (for example, X1Y1) is selected based on a preset order.

In step S27, the control unit 230 selects the part image 80 for inspection from the part images 80 of red (R), green (G), and blue (B) by the above-described selection method. In step S28, the control unit 230 reads out and selects the determination threshold Th (and the inspection algorithm) corresponding to the selected illumination color from the storage unit 31.

Then, in step S29, the control unit 230 performs the defect inspection processing shown in FIGS. 6(a) and 6(b) on the selected part image 80. Next, in step S30, it is judged whether or not the defect inspection of all (16 parts) inspection sites has been completed, and when the defect inspection of all the parts is not completed, the process returns to step S25 and shifts to the next portion (for example, X2Y1). an examination. The defect inspection of the entire solar battery cell 1 (imaging image 60) is performed by repeating steps S25 to S30 for all the portions.

When the defect inspection of all the parts is completed, the process proceeds to step S31, and it is judged whether or not the inspection result meets the predetermined determination condition for discriminating the good or defective product. The determination processing can be performed in the same manner as the result of the defect inspection for each part (the part image 80), and the processing of the entire captured image 60 is the same. The processing from step S31 to step S34 is the same as step S8 to step S11 of Fig. 7, and therefore the description thereof is omitted.

In the second embodiment, as described above, the control unit 230 is configured to obtain the part images 80 of various illumination colors for the plurality of parts (X1Y1 to X4Y4) of the solar battery cell 1 and to the solar battery cells 1 The part image 80 for inspection is selected for each part, and is checked based on the selected part image 80. Thereby, even when the film thickness d of the anti-reflection film 3 on each portion of the solar battery cell 1 is uneven, a captured image of the illumination color suitable for defect detection can be selected for each portion (portion) Image 80) performs defect detection, so defect detection can be performed with higher precision. In particular, when the size of the solar battery cell 1 is increased, the film thickness d of the anti-reflection film 3 at each portion is likely to be uneven, and therefore the visual inspection device 200 of the second embodiment is suitable for the large-sized solar battery cell 1. an examination.

The other effects of the second embodiment are the same as those of the first embodiment described above.

In addition, the embodiments disclosed herein are considered in all respects as illustrative and not restrictive. The scope of the present invention is not intended to be limited by the scope of

For example, in the first embodiment and the second embodiment described above, The present invention is applied to an example of an inspection apparatus provided on a production line of a solar battery cell and inspected on a line, but the present invention is not limited thereto. The present invention can also be applied to an inspection apparatus which is provided independently of the production line and is used for performing sampling inspection of the solar battery cells.

Further, in the first embodiment and the second embodiment, an example in which an illumination unit that can illuminate illumination light of three kinds of illumination colors of red (R), green (G), and blue (B) is provided is described. The invention is not limited to this. In the present invention, the number of illumination colors may not be three colors. For example, it can also be two colors of red and blue. Since the range of the unevenness of the film thickness of the antireflection film is limited, it is actually possible to perform defect inspection with high precision as long as it has at least two colors of red and blue. In addition, the illumination color can also be four or more colors. In this case, the illumination color of which color (wavelength) is set takes into consideration the unevenness of the film thickness which may occur with respect to the design value, and the illumination color which can perform appropriate defect detection within the range of unevenness which can be conceived It is better.

In addition, in the first embodiment and the second embodiment, the light source 11 (11a to 11c) of each color of red (R), green (G), and blue (B) is provided in the illumination unit, but The present invention is not limited to this. For example, a plurality of color filters corresponding to the illumination color may be used for a light source including a white light-emitting diode or the like so as to be able to illuminate illumination light of a plurality of colors. Further, as the light source, a light source other than the light emitting diode may be used.

Further, in the first embodiment and the second embodiment, it is shown that the light sources 11 (11a to 11c) of the respective colors are arranged in the RGB order in the holding portion of the illumination unit. Examples of the circumferential arrangement, but for example, each of the light sources may be a concentric circular three-circle light source row, and the ring of the red (R) light source 11a, the circle of the green (G) light source 11b, and the blue color (B) may be separately provided. a circle of the light source 11c. In the first embodiment and the second embodiment, the light sources are arranged side by side in a circumferential shape. However, the light sources may be arranged in a quadrangular shape. In this case, the shape of the diffusing reflection plate of the holding portion is formed in a pyramid shape, and an opening portion for guiding light to the imaging portion is provided at a vertex portion of the upper portion of the quadrangular pyramid.

Further, in the first embodiment and the second embodiment described above, an example in which a captured image for inspection is selected by any one of the first selection method to the third selection method is shown, but the present invention is not limited thereto. this. In the present invention, a captured image for inspection may be selected using a method different from the first to third selection methods. For example, a dedicated film thickness gauge may be separately provided to obtain the film thickness of the antireflection film, and the captured image may be selected based on the measurement result of the film thickness meter.

Further, when the light sources of red (R), green (G), and blue (B) are used as in the first embodiment and the second embodiment, the three colors constitute the three primary colors of the so-called light, and thus The hue of the surface of the solar cell unit is obtained from the ratio of the signal intensities of the captured images of the respective colors of RGB. As described above, the hue of the unit surface is expressed as a result of minimizing the reflection intensity of the color of the specific wavelength λ depending on the film thickness of the anti-reflection film, and thus can be based on the ratio of the signal intensities of the captured images of the respective colors of RGB. The specific wavelength λ at which the reflection intensity is minimized and the film thickness of the antireflection film are calculated. Can also be based on the specificity obtained from the ratio of the signal intensities of the three colors The captured image is selected by the value of the wavelength λ or the film thickness of the anti-reflection film.

Further, in the second embodiment described above, an example in which the captured image 60 is divided into 16 partial images 80 is shown, but the present invention is not limited thereto. In the present invention, the number of divisions of the part image may be a division number other than 16. The number of parts (part images) may be a number of parts (part images) that can obtain a required inspection accuracy depending on the size of the solar cell and the thickness unevenness of each part.

Further, in the second embodiment described above, an example in which the captured image is divided to obtain each part image is shown, but the present invention is not limited thereto. In the present invention, it is also possible to image each part of the solar battery cell by the imaging unit. That is, in the case where the size of the solar battery cell is large, the part image can be obtained by performing the imaging of the entire unit a plurality of times for each part. Further, for example, one solar battery unit may be divided into four to perform four shots, and the captured image may be divided into four parts to obtain a partial image of 16 parts.

Further, the specific numerical values described above (the size of the solar cell, the film thickness, the center wavelength of the light source of each color, and the like) are merely examples, and the present invention is not limited thereto. The size of the solar cell, the film thickness of the antireflection film, or the center frequency of the light source may be different values from the specific values described above.

1‧‧‧Solar battery unit

2‧‧‧Semiconductor substrate (polycrystalline semiconductor)

3‧‧‧Anti-reflective film

10‧‧‧Lighting Department

11‧‧‧Light source

12‧‧‧ Keeping Department

13‧‧‧ openings

20‧‧‧Photography Department

21‧‧‧ lens

30, 230‧‧‧Control Department

31‧‧‧ Storage Department

40‧‧‧ frame

70‧‧‧Defects

100, 200‧‧‧ visual inspection device (inspection device)

110‧‧‧Transporter

Claims (11)

An inspection device for a solar battery cell, which is an inspection device for a solar battery cell formed with an anti-reflection film, comprising: an illumination portion configured to illuminate illumination light with a plurality of illumination colors having mutually different wavelength regions An imaging unit that photographs the solar battery unit using the illumination light; and a control unit that obtains a captured image of the solar battery unit for each of the plurality of illumination colors, and according to the solar battery unit a reflection intensity of the illumination light of the illumination color or a film thickness of the anti-reflection film, and an image for inspection is selected from the captured images of the various illumination colors, and based on the selected The solar battery cell is inspected by taking a captured image. The inspection device for a solar battery cell according to claim 1, wherein the control unit is configured to reflect various types of the reflected light from a plurality of the captured images of the illumination colors. The captured image is selected by the signal intensity of the captured image of the illumination color, or the captured image is selected based on the film thickness of the anti-reflection film. The inspection apparatus for a solar battery unit according to claim 2, wherein the plurality of illumination colors include at least red and blue. The inspection device for a solar battery unit according to claim 3, wherein the control unit is configured to select the image map having a relatively low signal intensity from a plurality of the plurality of captured images of the illumination colors. Like, or choose to react with the anti-anti The captured image of the illumination color corresponding to the film thickness. The inspection device for a solar battery cell according to any one of the first to fourth aspect, wherein the control unit is configured to use a determination corresponding to the illumination color of the selected captured image. A threshold value is used to perform defect inspection on the anti-reflection film formed on the solar cell unit. The inspection device for a solar battery cell according to any one of claims 1 to 4, wherein the control unit is configured to obtain various illumination colors for each of a plurality of locations of the solar battery cell. a part image, and the part image for inspection is selected for each of the parts of the solar cell, and is inspected based on the selected part image. The inspection device for a solar battery unit according to claim 4, wherein the control unit is configured to compare an average value or a median value of signal intensities of the plurality of captured images, and select an average value or a medium value The captured image of the illumination color having the lowest value. The inspection device for a solar battery unit according to claim 4, wherein the control unit is configured to obtain various types by fitting the wavelength of the illumination light and the reflection intensity of the solar battery cell to a theoretical curve. a thickness of the anti-reflection film corresponding to a signal intensity of the image of the illumination color, and selecting the illumination corresponding to a predetermined film thickness range including a film thickness of the obtained anti-reflection film The captured image of the color. The inspection device for the solar cell unit as described in claim 4 The control unit is configured to obtain the reference material corresponding to the signal intensity of the captured image by using reference data that correlates the reflection intensity of each of the illumination colors with the film thickness of the anti-reflection film. The film thickness of the antireflection film is selected from the image of the illumination color corresponding to a predetermined film thickness range including the obtained film thickness of the antireflection film. The inspection device for a solar cell unit according to any one of the preceding claims, wherein the plurality of illumination colors comprise red, blue, and green. The inspection device for a solar battery cell according to any one of the preceding claims, wherein the solar battery cell comprises a polycrystalline semiconductor, and the antireflection film is a tantalum nitride film.