JP3935781B2 - Inspection device for transparent electrode film substrate - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an inspection apparatus for a transparent electrode film substrate so that defects (existence of pinholes or adhesion of foreign matter) of the transparent electrode film substrate for a thin film solar cell can be automatically detected online. It is a devised one.
[0002]
[Prior art]
A thin film solar cell is manufactured through a process of sequentially laminating a transparent electrode film, a semiconductor film, and a back electrode film on a transparent substrate. The dimension of the surface of this thin film solar cell is as large as 1.1 × 1.4 m, for example.
[0003]
By the way, when there are pinholes or foreign substances having a certain size or more on the transparent electrode film substrate in which the transparent electrode film is laminated on the transparent substrate, the semiconductor film and the back electrode are formed on the transparent electrode film substrate. Even if the thin film solar cell is manufactured by sequentially laminating the films, the photoelectric conversion rate of the finally completed thin film solar cell is poor and a predetermined power generation efficiency cannot be obtained.
[0004]
For this reason, it is indispensable to inspect the transparent electrode film substrate for defects before laminating the semiconductor film and the back electrode film on the transparent electrode film substrate.
[0005]
As an inspection method for a surface such as a transparent electrode film substrate which is a large area substrate, there is a method using a line sensor, but there is no online large area evaluation technique by color image processing.
Even if an area sensor is used to inspect a large-area substrate, if one area sensor is used, the resolution of the detected image is insufficient, and inspection is impossible in reality. When a plurality of area sensors are used, the resolution is sufficient, but the apparatus becomes large and the cost becomes high.
[0006]
Therefore, conventionally, the evaluation of defects such as pinholes generated on the transparent electrode film substrate and attached foreign matters has relied on visual inspection.
[0007]
[Problems to be solved by the invention]
However, when the defect inspection was performed visually, the inspection took time and fatigue was intense. Moreover, an accurate inspection could not be performed unless it was an expert.
[0008]
An object of the present invention is to provide an inspection apparatus for a transparent electrode film substrate, which can automatically and accurately inspect the transparent electrode film substrate of a thin film solar cell on-line, in view of the above prior art.
[0009]
[Means for Solving the Problems]
The configuration of the present invention that achieves the above object includes a moving device for moving a transparent electrode film substrate for a thin-film solar cell,
A color line sensor camera for photographing the surface of the transparent electrode film substrate that moves,
Position detecting means for detecting a moving position of the transparent electrode film substrate;
The color line sensor camera inspects the red component image signal, the green component image signal, and the blue component image signal of the color image signal obtained by photographing the transparent electrode film substrate. A defect indicating a defect present in the transparent electrode film substrate by forming a two-dimensional image representing the state of the surface of the transparent electrode film substrate on the basis of the movement position detected in this step, and performing image processing on the formed two-dimensional image. An image processing device for obtaining an image,
The image processing apparatus determines that there is no defect when the area of the defect image is smaller than a preset specified area,
If the area of the defect image is larger than the preset specified area and the intensity of the red component image signal, the green component image signal, and the blue component image signal all decrease by more than the specified value, foreign matter will adhere. It is determined that
A pinhole occurs when the area of the defect image is larger than the preset specified area and the red component image signal, the green component image signal, and the blue component image signal do not all behave more than the specified value. It is characterized in that it is determined.
[0010]
The configuration of the present invention includes a moving device for moving a transparent electrode film substrate for a thin film solar cell,
A color line sensor camera for photographing the surface of the transparent electrode film substrate that moves,
Position detecting means for detecting a moving position of the transparent electrode film substrate;
The color line sensor camera inspects the red component image signal, the green component image signal, and the blue component image signal of the color image signal obtained by photographing the transparent electrode film substrate. A defect indicating a defect present in the transparent electrode film substrate by forming a two-dimensional image representing the state of the surface of the transparent electrode film substrate on the basis of the movement position detected in this step, and performing image processing on the formed two-dimensional image. An image processing device for obtaining an image,
The image processing apparatus determines that there is no defect when the area of the defect image is smaller than a preset specified area,
If the area of the defect image is larger than the preset specified area and the intensity of the red component image signal, the green component image signal, and the blue component image signal all decrease by more than the specified value, foreign matter will adhere. It is determined that
The area of the defect image is larger than the preset specified area, and the red component image signal, the green component image signal, and the blue component image signal are not all reduced in intensity over the specified value. / If the aspect ratio is within the set value and the area occupancy of the defect image is equal to or greater than the set occupancy, it is determined that a pinhole has occurred.
[0011]
In addition, the configuration of the present invention includes a line illuminator that obliquely enters illumination light with respect to the surface of the transparent electrode film substrate,
The color line sensor camera is characterized in that the illumination light is disposed at a position where the reflected light reflected by the surface is incident.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below in detail with reference to the drawings.
[0013]
FIG. 1 shows a transparent electrode film substrate inspection apparatus according to an embodiment of the present invention. As shown in the figure, the transport conveyor 1 of this inspection apparatus transports the transparent electrode film substrate W to be inspected in the transport direction (Y direction) while maintaining the horizontal state. A color line sensor camera 2 and a line illuminator 3 are disposed above the conveyor 1. The line illuminator 3 is composed of a fluorescent lamp, for example, and the brightness is adjusted by the dimmer 4.
[0014]
As shown in FIG. 2, the color line sensor camera 2 and the line illuminator 3 are arranged so as to constitute a regular reflection type inspection apparatus. That is, the line illuminator 3 is disposed obliquely so that the emitted line illumination light L1 is incident on the surface (upper surface) of the transparent electrode film substrate W obliquely. The line illumination light L1 is reflected by the surface (upper surface) of the transparent electrode film substrate W to become line reflected light L2. On the other hand, the color line sensor camera 2 is obliquely arranged at a position where the line reflected light L2 is incident, and a portion of the surface of the transparent electrode film substrate W that is hit by the line illumination light L1 (line-shaped portion). Is supposed to shoot. That is, the color line sensor camera 2 and the line are set so that the incident angle θ1 of the line illumination light L1 incident on the transparent electrode film substrate W is equal to the reflection angle θ2 of the line reflected light L2 reflected by the transparent electrode film substrate W. The arrangement position of the illuminator 3 is set. In this inspection apparatus, θ1 and θ2 are set to angles between 17 ° and 18 °, respectively.
[0015]
Returning to FIG. 1 and continuing the description, a photoelectric switch 5 and a rotary encoder 6 are arranged on the conveyor 1. When the photoelectric switch 5 detects that the front end portion of the conveyed transparent electrode film substrate W has reached the incident position of the line illumination light L1, that is, the line-shaped photographing position photographed by the color line sensor camera 2. Then, an inspection start signal S is generated and sent to the image processing device 7. The rotary encoder 6 generates a pulse signal P and sends it to the image processing device 7 every set rotation angle, that is, every time the transparent electrode film substrate W moves a set distance.
[0016]
After receiving the inspection start signal S, the image processing device 7 sends a trigger signal T to the color line sensor camera 2 every time the pulse signal P is received. Each time the color line sensor camera 2 receives the trigger signal T, the color line sensor camera 2 photographs the transparent electrode film substrate W and sends a color image signal C having image information for one line to the image processing device 7. The color image signal C includes a red component image signal R, a green component image signal G, and a blue component image signal B.
[0017]
The image processing device 7 detects the signal levels of the red component image signal R, the green component image signal G, and the blue component image signal B of the color image signal C sent one after another, and the color image sent one after another. By arranging the signals C two-dimensionally on the memory, a two-dimensional image showing the surface image of the transparent electrode film substrate W is formed.
[0018]
Then, the image processing apparatus 7 detects pinholes generated on the transparent electrode film substrate W and attached foreign matter by performing defect determination processing by image processing described later. A waveform of the color image signal C and a two-dimensional image subjected to image processing are displayed on a display device (CRT) 8.
[0019]
In addition, a pinhole is the trace from which the foreign material peeled in the transparent electrode film board | substrate W, the part where the transparent electrode film is thin, and the part where a transparent electrode film does not exist. This pinhole looks circular when observed. Such a pinhole can be visually observed by configuring a specular reflection type inspection apparatus using the color line sensor camera 2 and the line illuminator 3.
Moreover, the foreign material adhering to the transparent electrode film substrate W looks black, and its shape is not limited.
[0020]
Here, when the experimental transparent electrode film substrate W in which pinholes are intentionally generated and the experimental transparent electrode film substrate W to which foreign substances are intentionally attached are inspected by the inspection apparatus shown in FIG. The situation of the color image signal C, the situation of the two-dimensional image (original image) showing the surface image of the transparent electrode film substrate W, and the situation of the processed image obtained by image processing of this original image will be shown.
[0021]
FIGS. 3A to 3H show pinholes obtained when the transparent electrode film substrate W for experiment in which various pinholes are intentionally generated is photographed with the color line sensor camera 2. The state of the color image signal C of the line being processed is shown.
That is, FIG. 3 shows a distribution diagram of the intensity of the RGB signal centered on the pinhole, where the horizontal axis is the X coordinate (coordinate in the color line sensor arrangement direction), and the vertical axis is the intensity of the RGB signal. Represents a level. The R signal means a red component image signal, the G signal means a green component image signal, and the B signal means a blue component image signal.
[0022]
As shown in FIG.
In the example of FIGS. 3A and 3B, all of the R signal, the G signal, and the B signal are changed (increased) at the position where the pinhole exists.
In the example of FIGS. 3C and 3D, the R signal and the G signal change (rise) at the position where the pinhole exists,
In the example of FIGS. 3E and 3F, only the R signal changes (increases or decreases) at the position where the pinhole exists.
In the examples of FIGS. 3G and 3H, only the G signal changes (falls) at the position where the pinhole exists.
[0023]
From the behavior of the color image signal C obtained by the experiment shown in FIG. 3, it was found that the RGB signal characteristics and data trends (up / down) are not constant when pinholes are generated. . Therefore, in order to detect a pinhole, the image processing device 7 detects all the information of the RGB signal, and performs edge detection, binarization, and expansion using a spatial filter for each of the RGB signals (original images). -It has been found that if there is a pinhole image that has been subjected to hole filling / shrinking processing and has an area larger than a specified value, it can be determined that a pinhole has occurred.
[0024]
Therefore, when the transparent electrode film substrate W used as a product is inspected by the inspection apparatus shown in FIG. 1, for example, when a color image signal (RGB signal) as shown in FIG. By detecting the edge of the color image signal (RGB signal) using a spatial filter, the signal shown in FIG. 4F is obtained.
[0025]
Further, a two-dimensional image (original image) shown in FIG. 4A is obtained by two-dimensionally arranging color image signals C including color image signals (RGB signals) as shown in FIG.
[0026]
By performing edge detection processing using a spatial filter on the original image, an edge detection processing image shown in FIG.
By binarizing the edge detection processing image, a binarization processing image shown in FIG. 4C is obtained.
By performing expansion / hole filling / shrinkage processing on the binarized image, a determination image including an image (an image of a white portion) showing a pinhole shown in FIG. 4D is obtained.
[0027]
In the image processing device 7, the size of the pinhole is determined from the size of the pinhole image (the white portion image) indicating the pinhole existing in the determination image. If the diameter φ of the pinhole is, for example, 1 mm or more, it is determined that the inspected transparent electrode film substrate W is defective.
[0028]
FIG. 5 shows the state of the color image signal C of the line where the foreign matter exists, obtained by photographing the experimental transparent electrode film substrate W to which the foreign matter is intentionally attached with the color line sensor camera 2. Is shown.
FIG. 5 is a distribution diagram of the intensity of the RGB signal. The horizontal axis represents the X coordinate (the coordinate in the arrangement direction of the color line sensors), and the vertical axis represents the intensity level of the RGB signal.
[0029]
As shown in FIG. 5, when a foreign object adheres, the RGB signal tends to decrease at the position where the foreign object adheres, and it is possible to identify the pinhole by evaluating the RGB signal. found.
[0030]
Further, a two-dimensional image (original image) is obtained by two-dimensionally arranging color image signals C including color image signals (RGB signals) as shown in FIG. 5, and this original image is subjected to edge detection processing by a spatial filter. By doing this, an edge detection processing image is obtained, and by binarizing the edge detection processing image, a binarization processing image is obtained, and this binarization processing image is expanded / filled / contracted By performing the above, a determination image including an image showing a foreign object (an image is shown as a white portion) is obtained.
[0031]
The image processing device 7 determines that foreign matter is attached when all the RGB signals tend to decrease, and further, the size of the foreign matter image (white portion image) indicating the foreign matter present in the judgment image. From this, the size of the foreign matter is determined. If the diameter φ of the foreign material is, for example, 1 mm or more, it is determined that the inspected transparent electrode film substrate W is defective.
[0032]
In addition, when it is detected by the substrate inspection that only foreign matters are attached and no pinholes are generated, the transparent electrode film substrate W can be recovered by removing the foreign matters by washing it with water or the like. Is possible. For this reason, it is necessary to distinguish between the adhesion of foreign matter and the occurrence of pinholes.
[0033]
The image processing apparatus 7 obtains a determination image (for example, an image as shown in FIG. 4D), and performs the following on a pinhole image or a foreign object image shown as an image of a white portion in such a determination image. Defect determination is performed using parameters (i), (ii), and (iii) (see FIG. 6).
(i) Defect area
(ii) Vertical / horizontal ratio
(iii) Occupancy ratio of defect area to circumscribed area. The defect area means an area of a pinhole image or a foreign material image.
[0034]
When the transparent electrode film substrate W to be inspected is actually inspected by the inspection apparatus shown in FIG. 1, the transparent electrode film substrate W is transported by the transport conveyor 1 and transparent by the color line sensor camera 2. The surface of the electrode film substrate W is photographed. Then, the image processing device 7 takes in the color image signal C. The image processing device 7 detects the signal levels of the red component image signal R, the green component image signal G, and the blue component image signal B of the color image signal C, and two-dimensionally arranges the color image signals C of many lines. As a result, an original image (for example, an image as shown in FIG. 4A) is formed, and the original image is determined by performing edge processing, binarization processing, expansion / hole filling / contraction processing using a spatial filter. An image (for example, an image as shown in FIG. 4D) is formed.
[0035]
Then, the image processing device 7 performs the following determination processes (A) to (D).
That means
(A) If the defect area is greater than or equal to the specified value, it is determined that there is a defect. For example, it is determined that there is a defect when the diameter φ is a defect area equivalent to 1 mm or more.
(B) It is determined whether the aspect ratio is within a specified value. This is performed to narrow down the defect shape by the aspect ratio. Here, for example, 1 ± 0.2 is set as the specified value.
(C) It is determined whether the defect area occupancy is equal to or greater than a specified value. This is to determine the degree of circularity from the ratio of the defect area to the circumscribed area. For example, in the case of a perfect circle, the occupation ratio is about 78.5%, so 78.5 ± 10% is set as the specified value.
(D) It is determined whether or not all the intensity reductions of the RGB signals are equal to or greater than a specified value. This is determined by examining the increase / decrease in the intensity of the color signal in the defective portion relative to the intensity of the color signal in the peripheral portion of the defective portion. Then, when all of the RGB signals are reduced by a predetermined value or more, it is determined that foreign matter is attached.
The prescribed value in the above determination is experimentally determined in advance as an optimum value and set.
[0036]
Here, the determinations of (B) and (C) will be further described. For example, as shown in FIG. 7, when determining patterns 1 and 2 having the same aspect ratio but different shapes, the shapes cannot be distinguished by the aspect ratio, but the defect shape is narrowed down by the occupation ratio. Is possible.
[0037]
The image processing apparatus 7 further has a determination logic as shown in FIG. 8, and determines the presence / absence of a defect and the type of defect based on this determination logic. This determination logic is formed by software.
[0038]
When the determination (A) is not established, that is, when the defect area is less than the specified value, it is determined that there is no defect.
[0039]
When the determination (A) is satisfied, that is, the defect area is equal to or larger than the predetermined value, and the determination (D) is satisfied, that is, when the decrease in all the intensity of the RGB signals is equal to or larger than the predetermined value, the foreign matter is attached. It is determined that
[0040]
Determination (B) is satisfied, that is, the aspect ratio is within the specified value, and determination (C) is satisfied, that is, the defect area occupancy is not less than the specified value. Further, determination (A) Is satisfied and the determination (D) is not satisfied, it is determined that a pinhole has occurred.
[0041]
When any of the determinations (B) and (C) is not established, it is not defined but is determined as another defect.
[0042]
In this way, it is possible to accurately and quickly inspect on-line for defects such as the presence of pinholes and adhesion of foreign matters in the transparent electrode film substrate W to be inspected.
[0043]
FIG. 9 shows the entire processing procedure of the inspection apparatus for the transparent electrode film substrate. That is, when the inspection start signal S is input and the pulse signal P is input, the trigger signal T is output (steps S1 to S7).
Then, the color image signal is taken in, and the color image signals of many lines (N lines) are two-dimensionally arranged (S8, S9), and defect detection processing (S10) and determination (S11) are performed. Further, the data is managed (S12) and the result is output (S13).
[0044]
【The invention's effect】
As specifically described with the above embodiments, in the present invention, a moving device for moving a transparent electrode film substrate for a thin film solar cell and a color line sensor camera for photographing the surface of the moving transparent electrode film substrate. Position detection means for detecting the movement position of the transparent electrode film substrate, and a red component image signal, a green component image signal, and a blue component image signal of a color image signal obtained by photographing the transparent electrode film substrate with the color line sensor camera. In addition to inspecting the intensity state, a two-dimensional image representing the state of the surface of the transparent electrode film substrate is formed on the basis of the color image signal and the moving position detected by the position detecting means. An image processing apparatus that obtains a defect image indicating a defect present in the transparent electrode film substrate by performing image processing;
The image processing apparatus determines that there is no defect when the area of the defect image is smaller than a preset specified area, the area of the defect image is larger than the preset specified area, and the red component image signal and the green component If the intensity of the image signal and the blue component image signal all decrease by a specified value or more, it is determined that foreign matter is attached, the area of the defect image is larger than a preset specified area, and red If the behaviors of the component image signal, the green component image signal, and the blue component image signal do not all decrease by a predetermined value or more, it is determined that a pinhole has occurred.
For this reason, it is possible to automatically and accurately detect the defect of the transparent electrode film substrate while distinguishing the adhesion of foreign matter and the occurrence of pinholes. As a result, stable defect detection is possible and thin-film solar cells with high photoelectric conversion efficiency can be manufactured, and on-line inspection of transparent electrode film substrates, which are large-area panels, can be performed on the production line, thereby improving the efficiency of thin-film solar cell production. Can be planned.
[0045]
In the present invention, the moving device for moving the transparent electrode film substrate for the thin film solar cell, the color line sensor camera for photographing the surface of the moving transparent electrode film substrate, and the moving position of the transparent electrode film substrate The position detection means for detecting, and inspecting the intensity state of the red component image signal, the green component image signal, and the blue component image signal of the color image signal obtained by photographing the transparent electrode film substrate by the color line sensor camera, and the color image The transparent electrode film substrate is formed by forming a two-dimensional image representing the surface state of the transparent electrode film substrate on the basis of the signal and the movement position detected by the position detecting means, and subjecting the formed two-dimensional image to image processing. And an image processing device for obtaining a defect image indicating a defect existing in
The image processing apparatus determines that there is no defect when the area of the defect image is smaller than a preset specified area, the area of the defect image is larger than the preset specified area, and the red component image signal and the green component If the intensity of the image signal and the blue component image signal all decrease by a specified value or more, it is determined that foreign matter is attached, the area of the defect image is larger than a preset specified area, and red The intensity of the component image signal, the green component image signal, and the blue component image signal do not behave as if they all decrease by more than a specified value , and the defect image area occupancy ratio is within the set value and the aspect ratio of the defect image. When is more than the set occupation rate, it is determined that a pinhole has occurred.
For this reason, pinholes can be generated more accurately.
[0046]
In the present invention, a line illuminator that illuminates illumination light obliquely with respect to the surface of the transparent electrode film substrate is provided, and the color line sensor camera receives reflected light reflected by the surface of the illumination light. It was set as the structure arrange | positioned in the position to do.
As a result, the color line sensor camera and the line illuminator constitute a specular reflection inspection apparatus, and even pinholes that are difficult to find can be reliably detected.
[Brief description of the drawings]
FIG. 1 is a configuration diagram showing a transparent electrode film substrate inspection apparatus according to an embodiment of the present invention.
FIG. 2 is a configuration diagram showing an arrangement relationship between a color line sensor camera and a line illuminator.
FIG. 3 is a signal waveform diagram illustrating a state of a color image signal when a pinhole is generated.
FIG. 4 is an explanatory diagram illustrating a situation of an original image, a processed image, and a color image signal.
FIG. 5 is a signal waveform diagram illustrating a state of a color image signal when a foreign object is attached.
FIG. 6 is an explanatory diagram showing inspection parameters.
FIG. 7 is an explanatory diagram showing different types of defects.
FIG. 8 is a logic diagram showing determination logic.
FIG. 9 is a flowchart showing an operation state of the inspection apparatus.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Conveyor 2 Color line sensor camera 3 Line illuminator 4 Dimmer 5 Photoelectric switch 6 Rotary encoder 7 Image processing apparatus 8 Display apparatus W Transparent electrode film substrate

Claims (3)

A moving device for moving a transparent electrode film substrate for a thin film solar cell;
A color line sensor camera for photographing the surface of the transparent electrode film substrate that moves,
Position detecting means for detecting a moving position of the transparent electrode film substrate;
The color line sensor camera inspects the red component image signal, the green component image signal, and the blue component image signal of the color image signal obtained by photographing the transparent electrode film substrate. A defect indicating a defect present in the transparent electrode film substrate by forming a two-dimensional image representing the state of the surface of the transparent electrode film substrate on the basis of the movement position detected in this step, and performing image processing on the formed two-dimensional image. An image processing device for obtaining an image,
The image processing apparatus determines that there is no defect when the area of the defect image is smaller than a preset specified area,
If the area of the defect image is larger than the preset specified area and the intensity of the red component image signal, the green component image signal, and the blue component image signal all decrease by more than the specified value, foreign matter will adhere. It is determined that
A pinhole occurs when the area of the defect image is larger than the preset specified area and the red component image signal, the green component image signal, and the blue component image signal do not all behave more than the specified value. An inspection apparatus for a transparent electrode film substrate, characterized in that it is determined that the substrate is being operated. A moving device for moving a transparent electrode film substrate for a thin film solar cell;
A color line sensor camera for photographing the surface of the transparent electrode film substrate that moves,
Position detecting means for detecting a moving position of the transparent electrode film substrate;
The color line sensor camera inspects the red component image signal, the green component image signal, and the blue component image signal of the color image signal obtained by photographing the transparent electrode film substrate. A defect indicating a defect present in the transparent electrode film substrate by forming a two-dimensional image representing the state of the surface of the transparent electrode film substrate on the basis of the movement position detected in this step, and performing image processing on the formed two-dimensional image. An image processing device for obtaining an image,
The image processing apparatus determines that there is no defect when the area of the defect image is smaller than a preset specified area,
If the area of the defect image is larger than the preset specified area and the intensity of the red component image signal, the green component image signal, and the blue component image signal all decrease by more than the specified value, foreign matter will adhere. It is determined that
The area of the defect image is larger than the preset specified area, and the red component image signal, the green component image signal, and the blue component image signal are not all reduced in intensity over the specified value. / Transparent electrode film substrate inspection apparatus, characterized in that pinholes are determined to occur when the aspect ratio is within a set value and the area occupancy rate of the defect image is greater than or equal to the set occupancy rate . In claim 1 or claim 2,
A line illuminator that illuminates illumination light obliquely with respect to the surface of the transparent electrode film substrate,
2. The transparent electrode film substrate inspection apparatus according to claim 1, wherein the color line sensor camera is disposed at a position where the reflected light reflected by the surface of the illumination light is incident.

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