Appearance inspecting device of solar cell

Abstract

To provide an appearance inspecting device of a solar cell which is capable of identifying the kind of a flaw in the solar cell and constructible easily.SOLUTION: The appearance inspecting device of the solar cell for detecting a defect part formed in the edge part of the solar cell includes an imaging device and an image background forming part. The imaging device can execute a first imaging operation for performing photographing by radiating light. The image background forming part is for absorbing the light radiated from the imaging device. The first imaging operation is executed in such a state that the solar cell is arranged between the imaging device and the image background forming part. When the defect part is detected on the basis of a first determination image formed by the first imaging operation, it is determined whether or not the detected defect part is a defect which does not penetrate the solar cell.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a solar cell appearance inspection device. [Background technology]

[0002] Conventionally, in the production process of solar cells, visual inspections are performed to ensure that there are no visual abnormalities. For example, Patent Document 1 discloses a visual inspection system that photographs the main surface of a semiconductor such as a solar cell so as to straddle both wiring and non-wiring areas, generates a processed image based on color information of the areas, and uses the processed image to detect visual abnormalities such as scratches and color unevenness. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2023-65861 Summary of the Invention [Problem to be solved by the invention]

[0004] Incidentally, one type of damage that can occur in a solar cell is a so-called crack, in which part of the edge of the solar cell is missing. This damage is formed by the loss of the solar cell from one main surface to the other main surface, and penetrates the solar cell. Another type of damage that can occur in solar cells is a so-called chip, which is a minute chip that gouges out part of the surface of the solar cell. This type of damage does not penetrate the solar cell.

[0005] Conventional visual inspection devices have room for improvement in terms of accurately identifying and detecting the differences in the types of minute scratches on solar cells. There has also been a desire to be able to detect such scratches without making the visual inspection device itself large-scale.

[0006] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide an easily configurable solar cell appearance inspection device that is capable of identifying the type of damage on a solar cell. [Means for solving the problem]

[0007] One aspect of the present invention for solving the above-mentioned problems is an appearance inspection device for solar cells that detects defective portions formed on the edge portions of solar cells, the appearance inspection device for solar cells having an imaging device and an image background forming unit, the imaging device being capable of performing a first imaging operation of irradiating light to take an image, the image background forming unit absorbing the light irradiated from the imaging device, the first imaging operation being performed with the solar cell positioned between the imaging device and the image background forming unit, and when the defective portion is detected based on a first determination image formed by the first imaging operation, the appearance inspection device for solar cells determines whether the detected defective portion is a defect that does not penetrate the solar cell.

[0008] According to this aspect, it is possible to accurately identify whether or not a detected defect portion is a defect that does not penetrate the solar cell, without making the device itself large-scale.

[0009] In a preferred aspect, the image background forming unit is a first color unit in which at least a portion of the surface facing the imaging device exhibits a first color, and the light emitted from the imaging device is light exhibiting a second color different from the first color, and the first color unit absorbs most of the light emitted from the imaging device, in the solar cell appearance inspection device described in claim 1.

[0010] According to this aspect, when determining whether or not a defective portion is a defect that does not penetrate the solar cell, it is possible to capture an image that is favorable for more accurate determination.

[0011] In a preferred aspect, the first color is blue and the second color is red, the imaging device is capable of performing a second imaging operation in which infrared light is irradiated to take an image, the second imaging operation is performed with the solar cell positioned between the imaging device and the image background forming unit, a second judgment image is formed by the second imaging operation, and a defect penetrating the solar cell is identified based on the first judgment image and the second judgment image.

[0012] According to this aspect, it is possible to more accurately identify the type of defect that a detected defect is.

[0013] A preferred aspect is that the device has a holding means for holding the solar cell, the holding means having a base end portion, a mid-portion extending from the base end portion, and a holding portion attached to the tip of the mid-portion for holding the solar cell, the mid-portion having the image background forming portion attached thereto, the mid-portion and the holding portion being movable in vertical and horizontal directions, and by moving the mid-portion and the holding portion the posture of the image background forming portion and the solar cell can be changed.

[0014] According to this aspect, adjustment of the positions and attitudes of the image background forming unit and the solar cell when capturing an image can be easily performed without requiring a complex mechanism.

[0015] In a preferred aspect, the solar cell is a back-contact type solar cell in which wiring is concentrated on the back surface side.

[0016] The solar cell appearance inspection device described above can be suitably used to detect defects formed on the edge of a back-contact type solar cell and to identify the type of defect. [Effects of the Invention]

[0017] According to the present invention, it is possible to provide an easily configurable solar cell appearance inspection device that can identify the type of damage on a solar cell. [Brief explanation of the drawings]

[0018] [Figure 1] 1 is a block diagram showing a visual inspection apparatus according to an embodiment of the present invention; [Figure 2] FIG. 2 is a perspective view showing an imaging unit and a cell transport unit in FIG. [Figure 3] 3(a) is a diagram showing the periphery of the hand unit in FIG. 2, and is an explanatory diagram showing the background forming member through a transparent view, and FIG. 3(b) is an explanatory diagram showing the periphery of the suction cup member in FIG. 3(a) as viewed from a different direction. [Figure 4] 2 is a flowchart showing the procedure of the appearance inspection performed by the appearance inspection device of FIG. 1. [Figure 5] 2 is an explanatory diagram showing the positional relationship between each part and a solar cell when the visual inspection apparatus of FIG. 1 performs a first imaging operation and a second imaging operation. FIG. [Figure 6] 1A and 1B are diagrams for explaining the first judgment image acquired by the visual inspection device of FIG. 1 through the first imaging operation, where (a) is an image of a solar cell and its surroundings captured through the first imaging operation, and (b) is an explanatory diagram tracing (a) and showing an enlarged view of the main parts. [Figure 7] 10A and 10B are diagrams for explaining the second judgment image acquired by the visual inspection device of FIG. 1 through the second imaging operation, where (a) is an image of the same object as in FIG. 6 captured through the second imaging operation, and (b) is an explanatory diagram tracing (a) and showing an enlarged view of the main parts. [Figure 8] 6A and 6B are diagrams for explaining the difference image generated by the visual inspection device of FIG. 1, where (a) is a difference image generated based on the first determination image shown in FIG. 6A and the second determination image shown in FIG. 7A, and (b) is an explanatory diagram tracing (a). DETAILED DESCRIPTION OF THE INVENTION

[0019] Hereinafter, embodiments of the present invention will be described in detail.

[0020] The appearance inspection apparatus 1 (appearance inspection apparatus for solar cells) of this embodiment has an imaging unit 2, a cell transport unit 3, and a control device 4, as shown in FIG. The appearance inspection device 1 is a device that inspects a back-contact type (back electrode type, back junction type) solar cell 100, in which both a p-type electrode and an n-type electrode are arranged on the back surface, and is capable of detecting defects formed on the edge of the solar cell 100 (details will be described later). More specifically, this solar cell 100 is a thin solar cell 100 intended to be mounted on the curved surface of an automobile or structure.

[0021] 2, the imaging unit 2 has a mount member 10, an illumination device 11, a light-transmitting member 12, and an imaging device 13. In detail, the imaging unit 2 is formed by attaching the illumination device 11 and the light-transmitting member 12 to the mount member 10, and disposing the imaging device 13 below the light-transmitting member 12.

[0022] The mounting member 10 is a frame-like body formed by framing vertical members and horizontal members.

[0023] The lighting device 11 is formed so as to have a general annular (circular) shape, and has a light-emitting portion 11a that emits light when lit, and a gap portion 11b. The light-emitting portion 11a is disposed adjacent to the void portion 11b and emits light upward (toward the solar cell 100 and the background forming member 21 described later). The light-emitting portion 11a in this embodiment is continuous in an annular (circular ring) shape so as to surround the void portion 11b. Although the lighting device 11 of this embodiment employs one light-emitting section 11a that is continuous in a ring shape, it is also possible to employ a configuration in which multiple light-emitting sections are arranged intermittently to surround the gap section 11b. The gap portion 11b is a gap portion (space) where no member is arranged, and is a portion where a through-hole that penetrates the lighting device 11 in the vertical direction is formed.

[0024] The lighting device 11 of this embodiment is a light-emitting device that can change the wavelength of the light it emits. In particular, the lighting device 11 is capable of performing a first light-emitting operation of emitting light exhibiting red color (second color), specifically, red light having a wavelength of approximately 660 nm. Furthermore, the lighting device 11 is capable of performing a second light-emitting operation of emitting infrared light, specifically near-infrared light with a wavelength of approximately 860 nm. That is, the light-emitting unit 11a has light sources (LEDs, specifically, red light LEDs and near-infrared light LEDs) that can emit these lights. Furthermore, the first light-emitting operation and the second light-emitting operation are operations that emit lights with different wavelengths.

[0025] The light-transmitting member 12 is a plate-like member that transmits light, and in this embodiment, an acrylic plate is used. The light-transmitting member 12 also functions as a protective member that protects the imaging device 13 from accidental dropping of the solar cell 100, etc.

[0026] The imaging device 13 is a camera with a monochrome shooting function, and is an area camera that captures an image of an object in a plane. That is, the imaging device 13 is a device that captures an image of an object and outputs a still image (image data). From the above, the imaging unit 2 of this embodiment is capable of performing a first imaging operation in which an image is captured while irradiating the object (the solar cell 100 and the background forming member 21 described later) with red light from the lighting device 11. The imaging unit 2 is also capable of performing a second imaging operation in which an image is captured while irradiating the object with infrared light from the lighting device 11. Both the first imaging operation and the second imaging operation of this embodiment are operations for capturing monochrome images.

[0027] The cell transport section 3 has a transport device 20 (holding means) and a background forming member 21 (image background forming section).

[0028] The conveying device 20 has a device main body 20a and a conveying means 20b supported by the device main body 20a. The transport means 20b has a hand unit 30 and an articulated arm unit 31 that movably operates the hand unit 30. As a result, the transport device 20 of this embodiment can move the entire hand unit 30 in three dimensions.

[0029] As shown in FIG. 3(a), the hand unit 30 has a base end side portion 35, a middle portion 36, and a holding portion 37, from the arm unit 31 side (see FIG. 2, base end side).

[0030] The midway portion 36 is a portion configured to include extending members 36a that extend in the vertical direction, and in this embodiment, is configured by a group of extending members 36a that are arranged in a matrix with spaces between them. For convenience of drawing, only some of the extension members 36a are labeled with reference numerals, and the reference numerals for the others are omitted. Similarly, in the following description, when the same item is depicted multiple times in each drawing, some of the reference numerals will be omitted as necessary. The extension member 36a is a cylindrical member that has a generally rod-like (round rod-like) shape and extends, and has a space inside.

[0031] The holding portion 37 is a portion configured to include suction cup members 37a which are holding members, and in this embodiment, is configured by a group of extension members 36a arranged in a matrix with spaces between them. The plurality of suction cup members 37a are attached to the tip end side of different intermediate portions 36, and are configured to adhere to the flat surface of the object to be inspected (solar cell 100). That is, the suction cup members 37a are made of an elastic material such as rubber or synthetic resin, and are bowl-shaped parts that are convex on the base end side and serve to hold the object to be inspected.

[0032] 3(b), the suction cup member 37a has a suction hole 40 formed at the bottom of the inner recess. When the suction cup member 37a holds the inspection object, the transport device 20 of this embodiment is capable of performing a suction operation to suck air from the space inside the suction cup member 37a.

[0033] More specifically, the transport device 20 has a suction device (not shown) and a suction path (not shown) formed between the tip-side opening (suction port) of the suction hole 40 and the suction device. As a result, the transport device 20 of this embodiment is able to perform a suction operation in which the tip-side portion of the suction cup member 37a is attached to the test object and the air inside the suction cup member 37a is sucked through the suction port, thereby sucking the test object by negative pressure. In other words, the transport device 20 has a holding mechanism that is capable of performing such a suction operation.

[0034] The background-forming member 21 is a flat plate-like member attached to the above-mentioned midway portion 36. That is, the background-forming member 21 has an attachment through-hole (detailed illustration is omitted) that penetrates the background-forming member 21 in the thickness direction, and a portion of the midway portion 36 is inserted into the attachment through-hole and extends through the background-forming member 21 in the thickness direction. When the cell transport unit 3 is oriented such that one main surface of the background forming member 21 faces downward, the plurality of suction cup members 37a are positioned below the background forming member 21. In other words, the plurality of suction cup members 37a are disposed adjacent to one main surface of the background forming member 21.

[0035] The background forming member 21 of this embodiment is partially or entirely a first color portion 21a that exhibits a first color, which is a predetermined color. The background forming member 21 of this embodiment has a first color that is blue, and a portion including one side in the thickness direction is the first color portion 21a that is blue. More specifically, one main surface of the background forming member 21 is a blue surface that is the first color portion 21a. The first color portion 21a may be formed by using a plate material at least a portion of which is colored the first color as the raw material for the background forming member 21, or by attaching tape of the first color to the plate material or applying paint of the first color to the plate material.

[0036] Here, the first color is a color that absorbs the second color (the color of light emitted by the lighting device 11, which is red). In other words, the first color may be any color that absorbs most of the light of the second color, and may be a color other than white, such as a color that is complementary to the second color, a color close to the complementary color of the second color (a color with a small hue difference from the complementary color), or black. However, from the perspective of detecting defects with higher accuracy, it is preferable that the first color and the second color be chromatic colors. Note that a "color with a small hue difference from the complementary color" is a color with a hue difference of 4 or less from the complementary color.

[0037] The control device 4 is a controller (small computer) having a central processing unit made up of an arithmetic unit that performs calculations on data, and is capable of inputting signals from external devices and outputting signals to external devices.

[0038] 1, the control device 4 includes a control unit 45, an image input unit 46, an image creation unit 47, and a defect identification unit 48, and is connected to a data storage unit 49 in a state in which information can be transmitted and received. The control device 4 and the data storage unit 49 function as the main body of the appearance inspection device.

[0039] The control unit 45 is a part (functional unit) that controls the imaging unit 2 and each device belonging to the cell transport unit 3.

[0040] The image input unit 46 is a part to which the images captured by the imaging unit 2 are input. That is, the image input unit 46 receives the first determination image (first determination image data, which will be described in detail later) acquired by the first imaging operation described above, and the second determination image (second determination image data, which will be described in detail later) acquired by the second imaging operation described above.

[0041] The image creation unit 47 is a part that creates a difference image (difference image data, which will be described in detail later) from the first and second determination images input to the image input unit .

[0042] The defect identification unit 48 is a part that determines whether or not there is a defect in the appearance of the photographed inspection object (solar cell 100) based on the first judgment image and the second judgment image, and identifies the type of defect.

[0043] The data storage unit 49 is a part that stores various data, and is an auxiliary storage device having storage means such as an HDD (hard disk drive), an SSD (solid state drive), etc. The data storage unit 49 stores images (first determination image, second determination image) acquired by imaging unit 2, difference images created by image creation unit 47, etc. The control device 4 may be a management computer having a hardware configuration including a central processing unit, a storage device for storing data, an input device for inputting data from the outside, and an output device for outputting data to the outside. In this case, the data storage unit 49 may be a storage device included in the control device 4, or may be an auxiliary storage device connected to the control device 4.

[0044] Next, the appearance inspection performed by the appearance inspection device 1 of this embodiment will be described with reference to FIG. When performing a visual inspection, the visual inspection device 1 moves the solar cell 100, which is the object to be inspected, to an imaging position (STEP 1). That is, as shown in Fig. 2 and Fig. 5, the transport device 20 holds the solar cell 100 with the holding unit 37, and moves the solar cell 100 to the imaging position above the imaging device 13.

[0045] At this time, the visual inspection device 1 is placed at the photographing position with the main surface of the solar cell 100 to be inspected parallel (or approximately parallel) to the horizontal plane, as shown in FIG. Note that "substantially parallel" here means that the main surface of the solar cell 100 is not only completely parallel to the horizontal plane, but also includes a case where the main surface is slightly inclined (within ±5 degrees).

[0046] At this time, the imaging unit 2 is arranged such that the gap 11b (see FIG. 2) of the illumination device 11, a part of the light-transmitting member 12, and a part (lens portion) of the imaging device 13 overlap in the vertical direction. In the imaging unit 2 of this embodiment, the distance L1 from the installation position of the imaging device 13 (the lower end portion of the imaging device 13) to the lower surface of the light-transmitting member 12 (the surface on the imaging device 13 side) is 240 mm ±50 mm. Note that the distance L1 is also the distance from the installation position of the imaging device 13 to the installation position of the light-transmitting member 12. In addition, the imaging unit 2 has a distance L2 from the installation position of the imaging device 13 to the installation position of the lighting device 11 (the lower end portion of the lighting device 11) of 430 mm ±50 mm. Furthermore, in the appearance inspection device 1, during imaging, the distance L3 from the installation position of the imaging device 13 to one main surface of the solar cell 100 (the main surface on the imaging device 13 side, that is, the lower surface) is 600 mm ±50 mm. That is, in this embodiment, the distance L1 from the installation position of the imaging device 13 to the installation position of the light-transmitting member 12 is longer than the distance L4 from the installation position of the light-transmitting member 12 to the installation position of the lighting device 11. Furthermore, this distance L4 is longer than the distance L5 from the installation position of the lighting device 11 to one main surface of the solar cell 100.

[0047] Here, as described above, the appearance inspection device 1 of this embodiment has the background forming member 21 attached to the midway portion 36. Therefore, when the appearance inspection device 1 moves the solar cell 100 to the shooting position and assumes the posture at the time of shooting, the background forming member 21 also moves to the position where it will be disposed at the time of shooting (the shooting position of the background forming member 21) and assumes the posture at the time of shooting. In other words, the appearance inspection device 1 of this embodiment can dispose the background forming member 21 at an appropriate position and in an appropriate posture without any additional alignment or the like. In this embodiment, background forming member 21 is placed at the photographing position so that first color portion 21a, which is one main surface (lower main surface), is parallel (or approximately parallel) to the horizontal plane. By placing background forming member 21 at the photographing position in this orientation, first color portion 21a is placed at a position above and spaced apart from the main surfaces of solar cells 100.

[0048] Next, the visual inspection device 1 executes the first imaging operation and the second imaging operation (STEP 2). Note that the first imaging operation and the second imaging operation may be executed in this order, or may be executed in the reverse order. In this embodiment, the positional relationship between the solar cell 100 and each part of the appearance inspection device 1 (illumination device 11, light-transmitting member 12, image capturing device 13, background forming member 21) when performing the first imaging operation is the same as the positional relationship between the solar cell 100 and each part of the appearance inspection device 1 when performing the second imaging operation. That is, the appearance inspection device 1 moves the solar cell 100 to the imaging position, sets it to the posture at the time of imaging, performs one of the first imaging operation and the second imaging operation, and then performs the other of the first imaging operation and the second imaging operation, leaving the solar cell 100 in the same position and posture.

[0049] Next, the visual inspection device 1 generates a difference image (STEP 3). That is, when the first imaging operation and the second imaging operation are executed, the first determination image (see FIG. 6) acquired by the first imaging operation and the second determination image (see FIG. 7) acquired by the second imaging operation are input to the image input unit 46. Then, the image creation unit 47 generates a difference image (see FIG. 8) based on the first determination image and the second determination image input to the image input unit 46.

[0050] Next, the appearance inspection device 1 identifies whether or not there is a defect in the edge portion of the solar cell 100, and if a defect is detected, identifies the type of defect (details of the defect) (STEP 4). In detail, the appearance inspection device 1 identifies whether or not there is a defect (defect) in the edge portion of the solar cell 100 that does not penetrate the solar cell 100, and whether or not there is a defect in the same edge portion that penetrates the solar cell 100. In the following description, a defective portion that does not penetrate the solar cell 100 is also referred to as a chip, and a defective portion that penetrates the solar cell 100 is also referred to as a crack.

[0051] 6, in the first determination image, the chip formed on the edge of the solar cell 100 (the part indicated by A in the figure) is captured in a shining state. On the other hand, in the first determination image, the crack formed on the edge of the solar cell 100 (the part indicated by B in the figure) is not captured or is barely captured. As a result, the defect identifying unit 48 analyzes the first determination image and identifies the pixels in the shining part on the solar cell 100 (which is captured in a bright white color), thereby making it possible to identify the presence or absence and position of the chip with high accuracy.

[0052] Here, in the second judgment image, as shown in Figure 7, both the chip (part indicated by A in the figure) and the crack (part indicated by B in the figure) are captured, and as with a typical photograph, the image makes it difficult to determine whether the defective part is a crack or a chip. Therefore, the visual inspection device 1 of this embodiment creates a difference image by subtracting the first judgment image from the second judgment image, and determines whether or not there is a crack by analyzing the difference image. That is, in the differential image, as shown in Fig. 8, the crack formed on the edge of the solar cell 100 (the part indicated by B in the figure) is clearly visible, while the chip (the part indicated by a in the figure) is not visible or is barely visible. As a result, the defect identifying unit 48 can analyze the differential image and identify the pixels of the cracked part on the solar cell 100 (the white part on the solar cell 100 in Fig. 7), thereby making it possible to identify the presence or absence and position of the crack with high accuracy.

[0053] In the appearance inspection device 1 of the above embodiment, the back contact type solar cell 100 is used as the inspection object, but the present invention is not limited to this, and a double-sided electrode type solar cell may also be used as the inspection object.

[0054] In the transport means 20b of the above-described embodiment, the hand unit 30 has the base end side unit 35, the intermediate unit 36, and the holding unit 37, but the present invention is not limited to this. The base end side portion 35 may be a part of the arm portion 31 , and the hand portion may be composed of a middle portion 36 extending from the arm portion 31 and a holding portion 37 . [Explanation of symbols]

[0055] 1. Visual inspection equipment (visual inspection equipment for solar cell) 13 Imaging device 20 Conveying device (holding means) 21 Background forming material 21a 1st color section 35 Base end side 36 Middle part 37 Holding part 100 solar cells

Claims

1. A solar cell appearance inspection device that detects defects formed on the edge of a solar cell, An imaging device and an image background forming unit are included, the imaging device is capable of performing a first imaging operation of irradiating light to capture an image, and the image background forming unit absorbs the light irradiated from the imaging device; An appearance inspection device for solar cells, which performs the first imaging operation with the solar cell positioned between the imaging device and the image background forming unit, and when the defective portion is detected based on the first determination image formed by the first imaging operation, identifies whether the detected defective portion is a defect that does not penetrate the solar cell.

2. the image background forming unit is a first color unit in which at least a part of a surface on the imaging device side exhibits a first color, and the light emitted from the imaging device exhibits a second color different from the first color, The solar cell visual inspection device according to claim 1 , wherein the first color section absorbs most of the light emitted from the imaging device.

3. the first color is blue and the second color is red; the imaging device is capable of performing a second imaging operation of irradiating infrared light and capturing an image; performing the second imaging operation while the solar cell is disposed between the imaging device and the image background forming unit, and forming a second judgment image by the second imaging operation; 3. The solar cell appearance inspection device according to claim 2, wherein a defect penetrating the solar cell is identified based on the first determination image and the second determination image.

4. a holding means for holding the solar cell, the holding means has a base end portion, a middle portion extending from the base end portion, and a holding portion attached to a tip of the middle portion to hold the solar cell, the intermediate portion is attached to the image background forming portion, 3. The solar cell appearance inspection device according to claim 1, wherein the intermediate portion and the holding portion are movable in vertical and horizontal directions, and the posture of the image background forming portion and the solar cell can be changed by moving the intermediate portion and the holding portion.

5. 3. The solar cell appearance inspection device according to claim 1, wherein the solar cell is a back-contact type solar cell in which wiring is concentrated on the back surface side.

Images