KR102684368B1 - Surface defect determination device, appearance inspection device and program - Google Patents

Abstract

When the object to be inspected (5) is moved relative to the lighting devices (2a), (2b) and the line sensor (1) arranged at different positions, the illumination light from each lighting device is switched one by one and irradiated to the object to be inspected. , each time the illumination light from each lighting device is switched, the reflected light from the object to be inspected is received by a line sensor and photographed, thereby acquiring a plurality of images in a state of positional deviation corresponding to the change in the illumination light; and It is provided with alignment means (10) for positioning images corresponding to each acquired lighting device, and discrimination means (10) for determining surface defects of the inspected object from the images aligned by the position alignment means. .

Description

Surface defect determination device, appearance inspection device and program

This invention relates to a surface defect determination device for determining surface defects of objects to be inspected, such as products or parts having a surface with strong regular reflection properties, and an appearance inspection device and program equipped with this surface defect determination device.

Scratches on the surface of a product or part spoil its appearance. Additionally, if the deposition plate for producing a thin film such as a film has irregularities due to scratches or the like, the irregularities are transferred to the manufactured thin film and become defects in the thin film.

Therefore, an external inspection device has been proposed for detecting surface defects of various products, parts, film-forming plates, etc.

For example, in Patent Document 1, there is a technology characterized by photographing a part while switching light sources in multiple directions and analyzing the direction of the illumination light source and the captured image to determine whether the shadow in the image is a defect or contamination. It has been disclosed.

Japanese Patent Publication No. 11-118450

However, the invention described in Patent Document 1 is based on the premise that the object to be inspected is stationary, and surface defects cannot be determined by, for example, inspecting a drum-driven belt component for which stopping control is difficult while moving the belt.

For this reason, there is a demand for a technology that can discriminate surface defects while relatively moving the object to be inspected for a lighting device or a line sensor that takes images.

This invention was made in consideration of this technical background, and provides a surface defect determination device, an appearance inspection device, and a program that can determine surface defects while moving the inspection object relative to the lighting device and line sensor. The purpose.

The above objective is achieved by the following means.

(1) When the object to be inspected is moved relative to the lighting devices and line sensors arranged at different positions, the illumination light from each lighting device is switched one by one to irradiate the object to be inspected, the illumination light from each lighting device is switched. Whenever possible, image acquisition means for acquiring a plurality of images in a state of positional deviation by the amount of conversion of the illumination light by receiving and photographing the reflected light from the inspected object with a line sensor, and each image acquired by the image acquisition means A surface defect determination device comprising alignment means for positioning an image corresponding to a lighting device, and discrimination means for discriminating surface defects of an object to be inspected from the image aligned by the position alignment means.

(2) A part of each pixel of the line sensor is an overlapping area where the shooting range overlaps between the current shooting and the previous shooting due to illumination light from one of the lighting devices being irradiated to the inspection object, and one When the part of a pixel excluding the overlapping area is used as a subpixel, the amount of light received in the overlapping area is subtracted from the amount of light received in the entire pixel in the current shooting to estimate the amount of light received in the current subpixel to produce a subpixel image. The surface defect determination device according to the preceding paragraph 1, comprising sub-pixel image production means, wherein the alignment means aligns sub-pixel images corresponding to each lighting device produced by the sub-pixel image production means.

(3) When the object to be inspected is moved relative to the lighting devices and line sensors arranged at different positions, the illumination light from each lighting device is switched one by one to irradiate the object to be inspected, the illumination light from each lighting device is switched. An image acquisition means is provided for acquiring a plurality of images for each illumination light by receiving and photographing reflected light from the inspected object with a line sensor whenever possible, and a portion of each pixel of the line sensor is one of the lighting devices. When the illumination light is irradiated to the object to be inspected and the shooting range overlaps with the current shooting and the previous shooting, forming an overlapping area, and the part excluding the overlapping area in one pixel is taken as a subpixel, this time A sub-pixel image production means for producing a sub-pixel image by estimating the light-reception amount of the current sub-pixel by subtracting the light-reception amount of the overlapping area from the light-reception amount of the entire pixel in the shooting, and the sub-pixel image production means to create a sub-pixel image. A surface defect determination device further comprising discrimination means for determining surface defects of an object to be inspected based on a pixel image.

(4) The surface defect determination device according to the preceding paragraph 3, comprising alignment means for aligning subpixel images corresponding to each lighting device produced by the subpixel image production means.

(5) The surface defect determination device according to any one of the preceding paragraphs 2 to 4, wherein the sub-pixel image production means subtracts the amount of light received in the overlapping area from the amount of light received in the entire pixel in a state in which the amount of light received in the overlapping area is corrected for each area.

(6) The sub-pixel image production means determines the received light amount of the overlapping area from the sum of the received light amounts of the sub-pixels estimated before last time, and subtracts the obtained light-received amount from the light-received amount of the entire pixel to estimate the light-received amount of the current sub-pixel. The surface defect discrimination device according to any one of the preceding paragraphs 2 to 5.

(7) The sub-pixel image production means estimates the average value obtained by dividing the light-receiving amount of all the first pixels after the start of shooting by the number of sub-pixels per pixel as the light-receiving amount of the first sub-pixel. The surface defect determination device according to the preceding paragraph 6.

(8) When the received light amount of all pixels does not exceed a predetermined threshold, the subpixel image production means estimates the average value of the received light amount of all pixels divided by the number of subpixels per pixel as the light received amount of the current subpixel, and , Surface defect determination according to any one of the preceding clauses 2 to 7, where, when the amount of light received by the entire pixel exceeds a predetermined threshold, the amount of light received by the overlapping area is subtracted from the amount of light received by the entire pixel, and the amount of light received by the current subpixel is estimated. Device.

(9) The position alignment means corrects the position alignment of the sub-pixel image corresponding to each lighting device produced by the sub-pixel image production means by correcting the luminance value K ⁱ _j to the correction value ^K'i _j according to the following equation. The surface defect discrimination device according to any one of the preceding paragraphs 2, 4 to 8, which is performed by doing so.

However, i: index of subpixel estimated position

j: Identification number of the lighting device that is on

(10) The determination means determines that, in the sub-pixel image aligned by the position alignment means, when the bright points corresponding to each lighting device do not overlap and each bright point is within a preset range, the surface of the object to be inspected is The surface defect determination device according to any one of the preceding paragraphs 1, 2, 4 to 9, which determines that a concave defect or a convex defect exists.

(11) The determination means determines that, in the subpixel image aligned by the position alignment means, if the position of the bright spot corresponding to each lighting device is opposite to the arrangement position of the lighting device, a concave defect exists, and the opposite is true. If not, the surface defect determination device according to item 10 of the preceding paragraph determines that a convex defect exists.

(12) When the bright spots corresponding to each lighting device overlap in the sub-pixel image aligned by the alignment means, the determination means determines that dust or dirt is present on the surface of the object to be inspected. The surface defect discrimination device according to any one of 1, 2, 4 to 11.

(13) Pixels whose total amount of light exceeds a predetermined threshold are detected as defect candidate pixels, sub-pixel images are aligned with the detected defect candidate pixels by the alignment means, and further inspected by the judgment means. The surface defect determination device according to any one of the preceding paragraphs 1, 2, 4 to 12, which determines surface defects of an object.

(14) The surface defect determination device according to any one of the preceding paragraphs 1 to 13, wherein an LED or a visible semiconductor laser is used as a light source of the lighting device.

(15) The surface defect determination device according to any one of the preceding paragraphs 1 to 14, wherein three or more lighting devices are arranged on a circumference centered on the line sensor at an angle difference of 360 degrees ÷ the number of lighting devices. .

(16) a plurality of lighting devices arranged at different positions, a line sensor capable of receiving reflected light of the illumination light irradiated from each lighting device to the object to be inspected, and moving the object to be inspected relative to the lighting device and the line sensor. Moving means, illumination control means for switching the illumination light from each lighting device one at a time at a predetermined period to irradiate the inspected object, and moving the inspected object relative to the lighting device and the line sensor by the moving means. , line sensor control means for controlling the line sensor to receive reflected light from the object to be inspected and perform imaging every time the illumination light from each lighting device is switched by the illumination control means; and An external inspection device comprising the surface defect determination device according to any one of the preceding claims.

(17) When the object to be inspected is moved relative to the lighting devices and line sensors arranged at different positions, the illumination light from each lighting device is switched one by one to irradiate the object to be inspected, the illumination light from each lighting device is switched. Whenever possible, an image acquisition step of acquiring a plurality of images in a state of position misalignment by the amount of conversion of the illumination light by receiving and photographing reflected light from the inspected object with a line sensor, and each image acquired by the image acquisition step A program for causing a computer to execute a positioning step for positioning an image corresponding to a lighting device, and a determination step for determining surface defects of an object to be inspected from the image positioned by the positioning step.

(18) A part of each pixel of the line sensor is an overlapping area where the shooting range overlaps between the current shooting and the previous shooting due to illumination light from one of the lighting devices being irradiated to the inspection object, and one When the part of a pixel excluding the overlapping area is used as a subpixel, the amount of light received in the overlapping area is subtracted from the amount of light received in the entire pixel in the current shooting to estimate the amount of light received in the current subpixel to produce a subpixel image. The computer is made to execute a sub-pixel image production step, and in the alignment step, the computer is made to execute a process of aligning the sub-pixel image corresponding to each lighting device produced by the sub-pixel image production step. Program listed in 17.

(19) In the sub-pixel image creation step, the program according to the preceding paragraph 17 causes the computer to execute a process of subtracting the received light amount of the overlapping area from the received light amount of the entire pixel in a state in which the amount of light received in the overlapping area is corrected for each area.

(20) In the subpixel image creation step, the received light amount of the overlapping area is obtained from the sum of the light received amounts of the subpixels estimated before last time, and the obtained light received amount is subtracted from the light received amount of the entire pixel to estimate the light received amount of the current subpixel. The program according to item 18 or 19 of the preceding paragraph that causes processing to be executed on the computer.

(21) In the sub-pixel image creation step, the computer is made to perform processing to estimate the received light amount of the first sub-pixel as the average value of the light-receiving amount of all the first pixels after the start of shooting divided by the number of sub-pixels per pixel. 20 of the preceding clause. Program listed in .

(22) In the subpixel image creation step, if the received light amount of all pixels does not exceed a predetermined threshold, the average value of the received light amount of all pixels divided by the number of subpixels per pixel is estimated as the received light amount of the current subpixel. , any of the preceding paragraphs 18 to 21, which causes the computer to execute processing to estimate the light reception amount of the current sub-pixel by subtracting the light reception amount of the overlapping area from the light reception amount of the entire pixel when the light reception amount of the entire pixel exceeds a predetermined threshold. Program listed in paragraph one.

(23) In the position alignment step, the position alignment of the subpixel image corresponding to each lighting device produced by the subpixel image production step is corrected by correcting the luminance value K ⁱ _j to the correction value ^K'i _j according to the following equation. The program according to any one of the preceding paragraphs 18 to 22, which causes the computer to execute the processing performed by doing so.

However, i: index of subpixel estimated position

j: Identification car number of the light that is on

(24) In the determination step, if, in the sub-pixel image aligned by the position alignment step, the bright points corresponding to each lighting device do not overlap and each bright point is within a preset range, the surface of the object to be inspected The program according to any one of the preceding paragraphs 17 to 23, which causes the computer to execute processing for determining that a concave defect or a convex defect exists.

(25) In the determination step, in the subpixel image aligned by the alignment step, if the position of the bright spot corresponding to each lighting device is opposite to the arrangement position of the lighting device, a concave defect exists, and the opposite The program according to item 24 of the preceding paragraph causes the computer to execute processing to determine that a convex defect exists if not.

(26) In the determination step, when bright points corresponding to each lighting device overlap in the pixel image aligned by the alignment step, processing is performed to determine that dust or dirt is present on the surface of the object to be inspected. The program according to any one of the preceding paragraphs 17 to 25 to be executed on the computer.

(27) Pixels whose total amount of light exceeds a predetermined threshold are detected as defect candidate pixels, sub-pixel images are aligned for the detected defect candidate pixels by the position alignment step, and further inspected by the judgment step. The program according to any one of the preceding paragraphs 17 to 26, which causes the computer to execute processing for determining surface defects of an object.

(28) The program according to any one of the preceding paragraphs 17 to 27, wherein an LED or a visible semiconductor laser is used as a light source of the lighting device.

(29) The program according to any one of the preceding paragraphs 17 to 28, wherein the plurality of lighting devices are arranged at positions of 360 degrees/(number of lighting devices) on a circumference centered on the line sensor.

According to the invention described in the preceding paragraph (1), while moving the object to be inspected relative to the lighting devices and line sensors arranged at different positions, the illumination light from each lighting device is switched one by one to illuminate the object to be inspected. Each time the illumination light from each lighting device is switched, the reflected light from the object to be inspected is received by a line sensor and photographed, so that a plurality of images are acquired with each position misaligned by the amount of the switched illumination light. After the acquired images corresponding to each lighting device are aligned, surface defects of the inspected object are determined from the aligned images.

In this way, since the object to be inspected is moving relative to the lighting device and the line sensor, each lighting device acquired from the line sensor is in a state of position misalignment by the amount of change in illumination light when the illumination light from each lighting device is switched. Since a plurality of images corresponding to are aligned and the surface defects of the inspected object are determined in this aligned state, the surface defects of the inspected object can be determined while moving the inspected object relatively.

According to the invention described in the preceding paragraph (2), a part of each pixel of the line sensor is an overlapping area where the shooting range overlaps between the current shooting and the previous shooting by illumination light from one lighting device being irradiated to the object to be inspected. When the portion excluding the overlapping area in one pixel is considered a subpixel, the received light amount of the overlapping area is estimated by subtracting the light received amount of the overlapping area from the light received amount of the entire pixel in the current shooting, and the subpixel is estimated. A pixel image is created. Then, the subpixel images corresponding to each manufactured lighting device are aligned, and surface defects of the inspected object are detected from the aligned images. Here, since the subpixel is a portion of the pixel excluding the overlapping area, it is smaller than one pixel. Because of this, the resolution of the appearance inspection is improved, and finer surface defects can be detected.

In short, when photographing a relatively moving inspection object with a line sensor, the distance between the line sensor and the photographing surface of the inspection object is not stable, so it is necessary to set a deep depth of field. However, if the depth of field is deepened, the resolution decreases. There is an off-axis relationship and there are cases where even fine defects cannot be inspected, but by using images of subpixels smaller than 1 pixel, resolution is increased without deepening the depth of field, which has the advantage of being able to inspect even finer defects. .

According to the invention described in the preceding paragraph (3), since defects are discriminated from subpixel images smaller than one pixel, the resolution of appearance inspection is improved, and finer surface defects can be detected.

According to the invention described in the preceding paragraph (4), defect detection with greater precision becomes possible by aligning the positions of subpixel images corresponding to each lighting device.

According to the invention described in the preceding paragraph (5), since the amount of light received in the overlapping area is subtracted from the amount of light received in the entire pixel in a state in which it is corrected for each area, the amount of light received in the current subpixel can be estimated by subtracting the more accurate amount of light received in the overlapping area. , Furthermore, defect discrimination with higher precision can be performed.

According to the invention described in the preceding paragraph (6), the received light amount of the overlapping area is determined from the sum of the received light amounts of the subpixels estimated before the previous time, and the obtained light received amount is subtracted from the light received amount of the entire pixel to estimate the light received amount of the current subpixel. Estimation processing is simplified.

According to the invention described in the preceding paragraph (7), the average value of the light received amount of all the first pixels after the start of shooting is divided by the number of subpixels per pixel is estimated as the light received amount of the first subpixel, so that the light received amount of the next and subsequent subpixels is Estimation processing can be performed smoothly.

According to the invention described in the preceding paragraph (8), when the amount of light received by the entire pixel does not exceed a predetermined threshold, in other words, when there is a high possibility that there is no surface defect, the amount of light received by the entire pixel is divided into the number of subpixels per pixel. The divided average value is estimated as the amount of light received by the current subpixel. On the other hand, when the received light amount of the entire pixel exceeds a predetermined threshold, in other words, when there is a high possibility that a surface defect exists, the received light amount of the current subpixel is estimated by subtracting the light received amount of the overlapping area from the light received amount of the entire pixel. . This allows defect determination processing to be performed by focusing on areas where surface defects are likely to exist.

According to the invention described in the preceding paragraph (9), it is possible to accurately align the subpixel images corresponding to each lighting device, and furthermore, determine defects with high precision.

According to the invention described in the preceding paragraph (10), concave defects or convex defects such as scratches on the surface of the object to be inspected can be discriminated.

According to the invention described in the preceding paragraph (11), it is possible to discriminate between concave defects and convex defects on the surface of the object to be inspected.

According to the invention described in the preceding paragraph (12), dust or dust on the surface of the object to be inspected can be determined.

According to the invention described in the preceding paragraph (13), pixels whose total amount of light exceeds a predetermined threshold are detected as defect candidate pixels, sub-pixel images are positioned with respect to the detected defect candidate pixels, and further, the surface of the inspected object is Since defects are identified, defect determination processing can be performed by concentrating on areas where surface defects are likely to exist.

According to the invention described in the preceding paragraph (14), since an LED or a visible semiconductor laser is used as a light source for the lighting device, switching of each lighting device can be performed with high speed.

According to the invention described in the preceding paragraph (15), three or more lighting devices are arranged on a circumference centered on the line sensor at an angle difference of 360 degrees ÷ the number of lighting devices, so that the illumination light is not at right angles due to scratches, etc. By ensuring that an illumination device is provided, surface defects such as scratches can be identified with good accuracy.

According to the invention described in the preceding paragraph (16), an external appearance inspection device is provided that can discriminate surface defects of an inspected object with high precision while moving the inspected object relative to the lighting device and line sensor disposed at different positions.

According to the invention described in the preceding paragraph (17) to (29), a computer can be made to perform surface defect determination processing on the inspected object while moving the inspected object relative to the lighting device and line sensor disposed at different positions.

1 is a configuration diagram of an external inspection device according to an embodiment of the present invention.
2 (a) and (b) are diagrams for explaining the arrangement relationship of a plurality of lighting devices.
FIG. 3 is a diagram for explaining the relative positional relationship between the photographing range and pixels when photographing while switching a plurality of lighting devices.
FIG. 4 is a diagram for explaining the relative positional relationship between the imaging range and pixels when the first to fourth shots are taken using one lighting device.
FIG. 5 is a diagram for explaining a method of estimating the amount of light received by the subpixel 23.
FIG. 6 is a diagram for explaining alignment of subpixel images for a plurality of lighting devices.
Fig. 7 is a diagram showing an example of the sensitivity distribution of pixels.
FIG. 8 is a diagram showing an example of the estimated amount of light received after correction for each area of the pixel, calculated taking into account the weighting of the sensitivity distribution of the pixel.
FIG. 9 is a diagram for explaining that since the distribution of the amount of irradiated light of a plurality of lighting devices is different, the amount of received light of the reflected light is also different depending on the area of the pixel.
Fig. 10 is a diagram for explaining a method for determining void defects.
Fig. 11 is a diagram for explaining a method for determining convex defects.
Fig. 12 is a diagram for explaining a method for determining scratches and defects.
Fig. 13 is a diagram for explaining a method for determining dust or dirt.
Fig. 14 is a diagram schematically showing an image determined to be a void defect by combining a plurality of subpixel images.
Fig. 15 is a diagram schematically showing an image determined to be a convex defect by combining a plurality of subpixel images.
Fig. 16 is a diagram schematically showing an image determined to be a scratch defect by combining a plurality of subpixel images.
Fig. 17 is a diagram schematically showing an image that is determined to be dust or dust by combining a plurality of subpixel images.

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of this invention will be described based on the drawings.

[Configuration of external inspection device]

1 is a configuration diagram of an external inspection device according to an embodiment of the present invention. As shown in FIG. 1, the appearance inspection device includes a line sensor 1, two lighting devices 2a and 2b, a lighting control unit 8 that controls each lighting device 2a and 2b, and a line sensor. A line sensor control unit (9) that controls (1), a conveyance drum (3, 3) that conveys the inspected object (5), a drum encoder (4) that detects the shooting position of the inspected object (5), and a display It is provided with a device 6, a computer 10, and a conveyance drum control unit 11 that controls the rotation speed of the conveyance drum 3 to control the conveyance speed of the inspected object 5.

The computer 10 processes the image captured by the line sensor 1 to determine defects and synchronously controls the lighting devices 2a and 2b and the line sensor 1. Additionally, the display device 6 displays images processed for defect determination by the computer 10, processing results, etc.

The inspected object 5 is in the form of a belt with high reflectivity, is installed in a roll shape using the conveyance drum 3, and is sent in the Y direction by rotation of the conveyance drums 3, 3 in the direction of the arrow. The photographing position of the inspected object 5 by the line sensor 1 is detected by the drum encoder 4.

The line sensor 1 is formed to extend in the When viewed, they are arranged at an angle difference of 180 degrees at the target position with the line sensor 1 as the center, making it possible to illuminate from two different directions. The opposing directions of the lighting devices 2a and 2b may be the X direction, the Y direction, or any other direction. In this embodiment, two lighting devices 2a and 2b are used, but three or more may be used. In the case of three or more, as shown in Fig. 2(b), they are arranged at an angle difference of 360 degrees ÷ the number of lighting devices on the circumference centered on the line sensor 1 when viewed from above, to prevent straight line scratches, etc. It is preferable that an illumination device that is not perpendicular to surface defects is always secured and that surface defects such as scratches can be distinguished with good precision. Additionally, in Fig. 2(b), there are three lighting devices 2a, 2b, and 2c, which are arranged at an angle of 120 degrees from each other.

Each lighting device 2a, 2b can be switched on and off at any timing under control from the lighting control unit 8.

When the shooting range of one line of the line sensor 1 is small with respect to the inspection target 5, the inspection target 5 is photographed once in the Y direction and then illuminated by the sensor illumination transport unit 12. The devices (2a, 2b) and the line sensor (1) are moved together in the You can also configure it to shoot .

The line sensor 1 moves the object 5 to be inspected in the Y direction, and switches each lighting device 2a and 2b on and off to receive reflected light when the object 5 to be inspected is illuminated. The line sensor (1) and each lighting device (2a, 2b) are not in opposite positions, and the illumination light from each lighting device (2a, 2b) is diffusely reflected from the inspection object (5) and is received by the line sensor (1). do. Therefore, the image captured by the line sensor 1 becomes a dark field image.

Since the surface of the object to be inspected (5) has a high reflectivity, if there are concave defects, convex defects, scratch-like defects, dust, dust, etc. at the lighting position, the reflected light diffusely reflected from these defects, dust, dust, etc. is transmitted to the line sensor (1). Join the company.

The line sensor control unit 9 and the lighting control unit 8 are connected to the computer 10, and the line sensor 1 and the lighting device 2a, and the line sensor 1 and the lighting device 2b synchronously emit light, respectively. It is filmed.

In this embodiment, the line rate of the line sensor 1 is set to 100 kHz (shutter speed 0.01 ms) based on the specifications of a general line sensor. In short, it is preferable to use an LED light source or an LD (visible semiconductor laser) light source that is switched alternately at high speed every 0.01 ms as the lighting device 2a and the lighting device 2b.

[Surface defect determination processing]

Next, the surface defect determination process of the inspected object 5 by the computer 10 will be described. Additionally, the computer 10 is equipped with a CPU, RAM, a memory device, etc., and the surface defect determination process is executed by the CPU operating according to an operation program stored in the memory device, etc.

As described above, imaging by the line sensor 1 is performed by alternately switching on and off a plurality of (two in this embodiment) lighting devices 2a, 2b while moving the inspected object 5. all. The computer 10 sequentially acquires images captured by the line sensor 1.

＜Creation of subpixel images＞

FIG. 3 is a diagram for explaining the relative positional relationship between the photographing range and the pixel 20 when photographing while switching the lighting devices 2a and 2b.

As shown in FIG. 3, the size of the detected defect 30 is 12 A, the resolution of the line sensor 1 (length of one pixel 20) is 6 A, and the object 5 to be inspected is illuminated each time A is sent. Let's take pictures while switching the devices 2a and 2b. The resolution of 6 A of the line sensor 1 is one imaging area for one pixel. Therefore, as shown in FIG. 3, the first photographing is performed by the illumination light of the lighting device 2a, and when the inspection object 5 is sent to A, the second photographing is performed and the photographing is performed by the illumination light of the illumination device 2b. Filming is done by In the first and second imaging, the imaging area of the inspected object 5 is moved by A. The same applies to the third and subsequent shots. In the example of FIG. 3, for convenience of explanation, the state in which the pixel 20 is moved by A is shown each time switching shooting is performed.

FIG. 4 is a diagram for explaining the relative positional relationship between the imaging range and the pixel 20 when the first to fourth imaging is performed using one lighting device 2a.

As shown in FIG. 4, paying attention to the lighting device 2a, the lighting device 2a turns on every time the inspected object 5 moves by 2 A, and irradiation of the inspected object 5 with the illumination light starts. and is photographed each time by the line sensor (1). In short, each time the object to be inspected 5 moves by 2 A, imaging corresponding to the illumination light from the lighting device 2a is performed. The irradiation time of the illumination light of the lighting device 2a, in other words, the light reception time of each pixel 20 of the line sensor 1, is a time corresponding to the movement distance A. These points are the same for the lighting device 2b.

In addition, as shown in FIG. 4, in imaging by the lighting device 2a, 4 A, which is a part of the sensor resolution 6 A, captures the same imaging range of the inspected object 5 in the current and previous imaging. It is an overlapping area with overlapping shooting ranges. In short, if the pixel 20 is divided into three regions, the first region 21, the second region 22, and the third region 23 in the longitudinal direction, the length of each region is 2 A, and the length of the previous region is 2 A. The second area 22 and the third area 23 in the shooting and the first area 21 and the second area 22 in the current shooting are overlapping areas with the same shooting range. For example, the first area 21 and the second area 22 in the fourth shooting overlap with the second area 22 and the third area 23 in the third shooting, respectively. In Fig. 4, the overlapping area between the current shooting and the previous shooting is displayed in gray.

Regarding the third area 23 of the current shooting, the shooting range with the previous shooting does not overlap, and is a part that is updated as a new shooting range, and is referred to as a subpixel. Hereinafter, the third area is also referred to as a subpixel.

FIG. 5 is a diagram for explaining a method of estimating the amount of light received by the subpixel 23, and shows the shooting range and pixel 20 when the i-th shooting and a plurality of times before and after the shooting are performed by the lighting device 2a. It shows the relative positional relationship of .

As shown in FIG. 5, in the i-th shooting, the amount of light received by the subpixel 23 is the same as that of the previous shooting, from the total amount of light received (6 A) of one pixel 20 in the i-th shooting. It is necessary to calculate and estimate the amount of light received by 4 A in the overlapping areas of the first area 21 and the second area 22.

In comparison with the (i-3) image, the (i-2) image is updated by 2 A of the subpixel 23, and the number of shots increases from the (i-1) image to the i image in order. In this way, the subpixel 23 is updated every 2 A minutes. The updated new subpixel 23 becomes an overlapping area in the next shooting, remains as an overlapping area again in the next shooting, and is excluded from the overlapping area in the next shooting. In short, the overlapping area between the current shooting and the previous shooting is the subpixel 23 from the past two shootings, the last time and the previous time. Therefore, in the i-th shooting, the amount of light received by the subpixel 23 is calculated from the total amount of light received for 6 A of 1 pixel in the i-th shooting, and the amount of light received by the subpixel 23 at the time of the previous (i-1)th shooting. It is the value obtained by subtracting the sum of the estimated light reception amount of and the estimated light reception amount of the subpixel 23 at the time of the previous (i-2)th shooting. in short,

(Estimated amount of light received by the i-th subpixel) = (Total amount of light received by the i-th subpixel) - {(Estimated amount of light received by the (i-1)th subpixel) + (Estimated amount of light received by the (i-2)th subpixel It is calculated as (estimate)}.

The numerical value written in each of the first to third areas 21 to 23 of each pixel 20 in FIG. 5 is an example of the estimated amount of light received in that area, and is the same as the numerical value of the subpixel 23 of the previous or previous time. The number on the right side of pixel 20 is the total amount of light received by one pixel. In the example in FIG. 5, the total amount of light received for 6 A of one pixel in the i-th shooting is 3.8, the estimated light-receiving amount of the subpixel 23 in the last (i-1)th shooting is 1.3, and the previous time ( Since the estimated light-receiving amount of subpixel 23 at the time of i-2) shooting is 0.5, the estimated light-receiving amount of subpixel 23 at the i-th shooting is [3.8 - (1.3 + 0.5)] = 2.0. do.

However, the estimation process for the amount of light received by the subpixel 23 may be performed on the pixel 20 detected as a defect candidate pixel with a high probability of having a defect, and the estimated position of the detected defect candidate pixel may be calculated using the drum encoder 4. ) Based on the information in i, the amount of light received by the subpixel 23 at that time is stored in relation to the position information, and a subpixel image can be produced. This allows defect determination processing to be performed by focusing on areas where surface defects are likely to exist, improving efficiency. Regarding the defect candidate pixel, the pixel 20 whose total amount of light exceeds a predetermined threshold can be detected as the defect candidate pixel.

In addition, for the pixel 20 whose total amount of light does not exceed the predetermined threshold, since there is a low possibility that a defect exists, the average value of the amount of light received by the pixel for 2 A is calculated as 1/3 of the amount of light received by the entire pixel, and the sub It can be estimated from the amount of light received by pixel 23 (for example, the (i-4)th or (i-3)th time in FIG. 5).

In addition, for the first shooting after the start of inspection, since there is no estimated light reception amount of the previous subpixel 23, the average value of the light reception amount of all pixels divided by the number of subpixels 23 per pixel is calculated as the average value of the first subpixel. It is sufficient to estimate the amount of light received by (23) and use this amount of light to estimate the amount of light received by subpixel 23 in subsequent imaging.

In this way, a subpixel image consisting of the light reception amount of 1/3 pixel (2 A equivalent area) is produced, rather than an image of the pixel 20, around the defect candidate pixel. As a result, the resolution of the line sensor 1 is tripled, allowing fine surface defects to be detected and discriminated with good precision. In short, when photographing an inspection object (5) moving with respect to the line sensor (1) and the lighting devices (2a, 2b) with the line sensor (1), the distance between the line sensor (1) and the photographing surface of the inspection object (5) is The distance is not stable, so it is necessary to set the depth of field to a large depth. However, there is a trade-off in that the deeper the depth of field, the lower the resolution, and there are cases where even fine defects cannot be inspected, but images of subpixels smaller than 1 pixel are used. By using , resolution increases without increasing the depth of field, and even finer defects can be inspected.

Although a subpixel image was created for the lighting device 2a, a 1/3 pixel subpixel image can be created in the same way for the lighting device 2b.

<Alignment of sub-pixel images with respect to lighting devices (2a, 2b)>

As shown in FIG. 6, the positions of the subpixel image for one pixel 20 corresponding to the lighting device 2a are a1, a2, a3... , and the positions of the subpixel image for one pixel 20 corresponding to the lighting device 2b are b1, b2, b3... In this case, since the object 5 is moving with respect to the line sensor 1 and the lighting devices 2a and 2b during imaging, the subpixel image for the lighting device 2a and the lighting device 2b are displayed. The subpixel images for are a1, b1, a2, b2, a3, b3... As shown, the position is alternately shifted by the movement distance A corresponding to the switching time of the illumination light.

So, this positional misalignment is corrected. Specifically, if the position of the subpixel of the lighting device 2b corresponding to the position a2 of the lighting device 2a is b2',

Amount of light received at position b2' (luminance value) = (Amount of light received at position b1 + Amount of light received at position b2)/2

As such, the positional misalignment is corrected by correcting the amount of light received (luminance value). Position a3, a4 of lighting device (2a)... The positions of subpixels of the lighting device 2b corresponding to b3', b4'... The same is true for .

Additionally, the position of the lighting device 2a is determined by the positions b1, b2, b3... of the lighting device 2b. You may adjust the position to correspond to .

The above correction equation is for the case where there are two lighting devices, but the correction equation that can be applied regardless of whether there are two or three or more lighting devices is expressed as the following equation.

However, i: index of subpixel estimated position

j: Identification number of the lighting device that is on

＜Correction when estimating the received light amount of subpixels＞

The estimation of the amount of light received by the subpixel 23 was performed assuming that all areas of 6 A of one pixel had the same light reception sensitivity. However, in reality, as shown in the sensitivity distribution in FIG. 7, the light-receiving sensitivity is different depending on each part of the pixel 20, with the central portion having relatively high light-receiving sensitivity and both ends having low light-receiving sensitivity. Figure 7 shows that the sensitivity of the hatched portion is high, and the third region has higher sensitivity than the first region at both ends as well.

As explained in FIG. 5, if the current shooting is the i-th shooting, in the (i-1)th shooting, which is the previous shooting, the subpixel is the third area 23 at the right end of one pixel, and the light receiving Sensitivity is low. This subpixel 23 overlaps with the second area 22 in the center 2A in this i-th shooting, and this area has high light reception sensitivity. For this reason, the amount of light received by the central second area 22 in the i-th imaging will be greater than the amount of light received by the subpixel 23 in the (i-1)-th imaging.

In addition, the amount of light received by the first area 21 in the i-th shooting is the amount of light received by the subpixel 23 in the (i-2)th shooting. The amount of light received by the first area 21 in the i-th shooting will actually be less than the amount of light received by the subpixel 23.

Therefore, in order to correct the amount of light received in each area 21 to 23 of the pixel 20, weighting appropriate for each area 21 to 23 is performed, and a weight coefficient is set for each area 21 to 23. Specifically, the weight coefficient of the first area 21 at the left end of one pixel 20 is ε1, the weight coefficient of the second area 22 at the center is ε2, and the weight coefficient of the third area 23 at the right end is ε2. Taking ε3, the amount of light received by the subpixel 23 in the i-th shooting is calculated using the following equation.

(Estimated amount of light received by the i-th subpixel) = (Total amount of light received by the i-th subpixel) - {(Estimated amount of light received by the (i-1)th subpixel) * ε2/ε3 + ((i-2)th sub Estimate of the amount of light received by the pixel) * ε1/ε3}

As specific examples of ε1, ε2, and ε3, in this embodiment, ε1 = 1/3, ε2 = 1, and ε3 = 2/3 are set. Fig. 8 shows an example of the estimated amount of light received after correction for each area 21 to 23 calculated by taking weighting into consideration.

In the example of Fig. 8, when the amount of light received by the subpixel 23 at the time of the (i-2)th shooting is set to 0.3, the amount of light received in the second area 22 at the time of the (i-1)th shooting is It is corrected and increased to 0.5, and in the first area 21 at the time of the ith shooting, the amount of received light is corrected and reduced to 0.2. Additionally, when the amount of light received by the subpixel 23 at the time of the (i-1)th shooting is set to 0.9, the amount of light received in the second area 22 at the time of the i-th shooting is corrected and increased to 1.3.

In addition, since not only the light-receiving sensitivity of the pixel 20 but also the distribution of the amount of irradiated light of the lighting devices 2a and 2b is different, as shown in FIG. 9, the amount of received light of the reflected light 40 is also different in the area of the pixel 20. Therefore, there are different cases. In the example of FIG. 9, the amount of reflected light is 1 for the first and third areas 21 and 23 at the ends of the pixel 20, and the amount of reflected light is twice that for the second area 22 in the center. there is. For this reason, in order to correct the difference in the amount of reflected light, the weight coefficients ε1 to ε3 may be set based on each region 21 to 23 of the pixel 20. For example, ε1 = 1/2, ε2 = 1, and ε3 = 1/2 may be set.

In this way, with the received light amount corrected for each of the areas 21 to 23 of the pixel 20, the received light amount of the overlapping area is subtracted from the light received amount of the entire pixel, so a more accurate received light amount of the overlapping area is subtracted to determine the current subpixel ( 23) The amount of received light can be estimated, and defect discrimination can be performed with higher precision.

＜Defect determination＞

Surface defects are determined based on subpixel images aligned with each other.

Among the concave defects, regarding the spherical concave defect 51 called a "void defect", as shown in FIG. 10, illumination light from different directions of the opposingly arranged lighting devices 2a and 2b crosses, causing the lighting device to The positional relationship between each position in (2a and 2b) and the reflection position is reversed. In short, in the aligned subpixel image 61, the bright points 61a and 61b corresponding to each lighting device 2a and 2b do not overlap, and each bright point 61a and 61b is within a preset range. , Furthermore, if the positions of the bright points 61a and 61b have a positional relationship opposite to the arrangement positions of the lighting devices 2a and 2b, it is determined to be a concave defect 51.

On the other hand, regarding the "convex defect", as shown in FIG. 11, each illumination light from the lighting devices 2a and 2b to the convex defect 52 does not cross, but reflects with the respective positions of the lighting devices 2a and 2b. The positions have the same positional relationship. Therefore, in the aligned subpixel image 62, the bright spots 62a and 62b corresponding to each lighting device 2a and 2b do not overlap, and each bright spot 62a and 62b is within a preset range. Furthermore, if the positions of the bright points 62a and 62b have the same positional relationship with the arrangement positions of the lighting devices 2a and 2b, it is determined to be a convex defect 52.

10 and 11, bright points 61a and 62a corresponding to the lighting device 2a are shown with double hatching, and bright points 61b and 62b corresponding to the lighting device 2b are shown with broken line hatching. The same applies to Fig. 12 and beyond.

Among the concave defects, regarding the planar defect 53 called a "scratching defect", as shown in FIG. 12, the illumination light from the opposingly arranged lighting devices 2a and 2b crosses, and the lighting devices 2a and 2b ) The positional relationship between each position and the reflection position is reversed. Additionally, since the direction of the scratch surface is not constant, reflection of the illumination light from the lighting device 2a and reflection of the illumination light from the lighting device 2b coexist. However, because the flat surface is a highly reflective surface, each illumination light is mixed and not reflected. Accordingly, in the aligned subpixel image 63, the bright spot 63a corresponding to the lighting device 2a and the bright spot 63b corresponding to the lighting device 2b do not overlap, and each bright spot 63a, 63b) are mixed and the positions of the bright points 63a and 63b are opposite to the arrangement positions of the lighting devices 2a and 2b, it is determined that a scratch defect 53 exists on the surface of the inspected object 5.

Since the surface of the “dust” or “ticle” is a diffuse reflection surface, it diffusely reflects the illumination light of the lighting devices 2a and 2b. For this reason, as shown in FIG. 13, each illumination light is mixed and reflected by the defect 54. do. Therefore, in the aligned subpixel image 64, when the bright spots 64a and 64b corresponding to each lighting device 2a and 2b overlap, dust or dust is present on the surface of the inspected object 5. Decide that you do.

Each subpixel image produced by the lighting devices 2a and 2b is a dark field image, and uneven defects, scratch defects, dust, dust, etc. appear as white spots. Detection of defect candidates on an image is performed as follows.

That is, when the size of the defect candidate is set to be greater than or equal to W1 and less than or equal to W2 in terms of the image area, and the luminance is set to greater than or equal to B2, each subpixel image is all binarized to B2, and a collection process of discrete pixels is performed by expansion and contraction processing. Additionally, a label is assigned to each pixel set by color classification or the like.

Only the pixel set of the label whose set area S is W1 ≤ S ≤ W2 is left, and the other pixel sets are deleted from each subpixel image. W1 does not simply represent the minimum defect size, but represents the minimum size that can be considered a “defect part.”

Then, when the defect size is defined as 2b) If there is a set of pixels within the range of coordinates Vi ± It is classified into four types: ", "dust or dust".

Specifically, as shown in FIG. 14, if the aligned subpixel image SPa corresponding to the lighting device 2a and the subpixel image SPb corresponding to the lighting device 2b are combined as shown in the drawing on the right, each The bright points 61a, 61b corresponding to the lighting devices 2a, 2b do not overlap, and each bright point 61a, 61b is within the range of coordinates Vi ± X/2, and the positions of the bright points 61a, 61b are Since the positional relationship is opposite to that of the lighting devices 2a and 2b, it is determined to be a void defect.

As shown in FIG. 15 , when the aligned subpixel image SPa corresponding to the lighting device 2a and the subpixel image SPb corresponding to the lighting device 2b are combined as shown in the drawing on the right, each lighting device 2a , 2b), the corresponding bright points (62a, 62b) do not overlap, and each bright point (62a, 62b) is within the range of coordinates Vi ± Since it has the same positional relationship as the arrangement positions of 2a and 2b), it is determined to be a convex defect.

As shown in FIG. 16, when the aligned subpixel image SPa corresponding to the lighting device 2a and the subpixel image SPb corresponding to the lighting device 2b are combined as shown in the drawing on the right, each lighting device 2a , 2b), each bright point (63a, 63b) is within the range of coordinates Vi ± Since it is opposite to the arrangement position of 2a, 2b), it is judged as a scratch defect.

As shown in FIG. 17, when the aligned subpixel image SPa corresponding to the lighting device 2a and the subpixel image SPb corresponding to the lighting device 2b are combined as shown in the drawing on the right, each lighting device 2a Since the bright points 64a and 64b corresponding to , 2b) overlap, it is determined to be dust or dust.

By the above, surface defects of the moving object to be inspected 5 can be detected and discriminated.

The detection result is displayed on the display device 6. The display is preferably an image after alignment of the two subpixel images SPa and SPb shown on the right side of FIGS. 14 to 17, along with the type of the identified defect and the range of coordinates Vi ± X/2 for each defect. may also be displayed.

Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment. For example, the line sensor 1 and the lighting devices 2a, 2b are fixed and the image is taken while the inspected object 5 is moved. However, the inspected object 5 is fixed and the line sensor 1 is And the imaging may be performed while moving the lighting devices 2a and 2b, and at least one of the inspected object 5, the line sensor 1 and the lighting devices 2a and 2b may be moved relative to the other.

In addition, the case where the relative moving distance per shot of the object 5 to be inspected is A and the length of the subpixel 23 is 2 A was shown, but for one lighting device, the shots were taken in the current shot and the previous shot. All that is necessary is for the overlap of the range to occur to form a subpixel. For this reason, it is recommended that the relative moving distance per image of the inspected object 5 be less than 1/2 of one pixel.

In addition, although two lighting devices 2a and 2b were used, three or more lighting devices were switched in order as described above, and defects were identified by comparing three or more types of subpixel images corresponding to each lighting device. Detection and discrimination is preferable because the direction of irradiated light can be varied and surface defects can be detected and discriminated with better precision.

Industrial applicability

The present invention can be used when determining surface defects of objects to be inspected, such as products or parts having a surface with strong regular reflection properties.

1: Line sensor
2a, 2b: lighting device
4: Drum encoder
5: Test object
6: Lighting device
8: Lighting control unit
9: Line sensor control unit
10: computer
11: Drum conveyance control unit
20: Pixel
21: first area
22: Second area
23: Subpixel (third area)
30: defect
51: Concave defect (void defect)
52: Convex defect
53: scratch defect
54: dust or dust
61a to 64a: Bright spot by lighting device (2a)
61b to 64b: Bright spot by lighting device (2b)

Claims (29)

When the object to be inspected is moved relative to the lighting devices and line sensors arranged at different positions, the illumination light from each lighting device is switched one by one to irradiate the object to be inspected, each time the illumination light from each lighting device is switched. , image acquisition means for acquiring a plurality of images in a state of positional deviation corresponding to the conversion of the illumination light by receiving and photographing reflected light from the object to be inspected with a line sensor;
Positioning means for positioning images corresponding to each lighting device acquired by the image acquisition means;
Provided with discrimination means for determining surface defects of the inspected object from the image aligned by the alignment means,
A part of each pixel of the line sensor is an overlapping area where the shooting range overlaps between the current shooting and the previous shooting due to illumination light from one of the lighting devices being irradiated to the inspection object,
When the part of one pixel excluding the overlapping area is used as a subpixel, the received light amount of the overlapping area is estimated by subtracting the light received amount of the overlapping area from the light received amount of the entire pixel in the current shooting to create a subpixel image. Provided with a sub-pixel image production means for producing,
A surface defect determination device wherein the alignment means aligns subpixel images corresponding to each lighting device produced by the subpixel image production means. delete When the object to be inspected is moved relative to the lighting devices and line sensors arranged at different positions, the illumination light from each lighting device is switched one by one to irradiate the object to be inspected, each time the illumination light from each lighting device is switched. Provided with image acquisition means for acquiring a plurality of images for each illumination light by receiving and photographing reflected light from the inspected object with a line sensor,
A part of each pixel of the line sensor is an overlapping area where the shooting range overlaps between the current shooting and the previous shooting due to illumination light from one of the lighting devices being irradiated to the inspection object,
When the part of one pixel excluding the overlapping area is used as a subpixel, the received light amount of the overlapping area is estimated by subtracting the light received amount of the overlapping area from the light received amount of the entire pixel in the current shooting to create a subpixel image. A sub-pixel image production means for producing,
A surface defect determination device further comprising discrimination means for determining surface defects of an object to be inspected based on a subpixel image produced by a subpixel image production means. According to claim 3,
A surface defect determination device comprising alignment means for aligning subpixel images corresponding to each lighting device produced by the subpixel image production means. The method according to any one of claims 1 and 3 to 4,
A surface defect determination device in which the sub-pixel image production means subtracts the amount of light received in the overlapping area from the amount of light received in the entire pixel in a state in which the amount of light received in the overlapping area is corrected for each area. The method according to any one of claims 1 and 3 to 4,
The subpixel image production means determines the received light amount of the overlapping area from the sum of the received light amounts of the subpixels estimated before last time, subtracts the obtained light received amount from the light received amount of the entire pixel to estimate the light received amount of the current subpixel, and determines surface defects. Device. According to claim 6,
The sub-pixel image production means estimates the average value obtained by dividing the light-receiving amount of all first pixels after the start of shooting by the number of sub-pixels per pixel as the light-receiving amount of the first sub-pixel. The method according to any one of claims 1 and 3 to 4,
When the received light amount of all pixels does not exceed a predetermined threshold, the subpixel image production means estimates the average value of the received light amount of all pixels divided by the number of subpixels per pixel as the light received amount of the current subpixel, and When the received light amount exceeds a predetermined threshold, the surface defect determination device estimates the light received amount of the current subpixel by subtracting the light received amount of the overlapping area from the light received amount of the entire pixel. According to claim 1 or 4,
The position alignment means performs alignment of the subpixel image corresponding to each lighting device produced by the subpixel image production means by correcting the luminance value K ⁱ _j with the correction value ^K'i _j according to the following equation. Defect determination device.

However, i: index of subpixel estimated position
j: Identification number of the lighting device that is on According to claim 1 or 4,
The determination means determines whether, in the sub-pixel image aligned by the position alignment means, the bright points corresponding to each lighting device do not overlap and each bright point is within a preset range, the surface of the object to be inspected has a concave defect. Or a surface defect determination device that determines that a convex defect exists. According to claim 10,
The determination means determines that, in the subpixel image aligned by the alignment means, a concave defect exists when the position of a bright spot corresponding to each lighting device is opposite to the arrangement position of the lighting device, and when the opposite is not the case, A surface defect determination device that determines that a convex defect exists. According to claim 1 or 4,
The determination means is a surface defect determination device that determines that dust or dirt is present on the surface of the object to be inspected when bright spots corresponding to each lighting device overlap in the subpixel image aligned by the alignment means. . According to claim 1 or 4,
Pixels whose total amount of light exceeds a predetermined threshold are detected as defect candidate pixels, sub-pixel images are aligned for the detected defect candidate pixels by the alignment means, and the judgment means is used to align the surface of the inspected object. A surface defect determination device that determines defects. The method according to any one of claims 1 and 3 to 4,
A surface defect determination device in which an LED or a visible semiconductor laser is used as a light source of the lighting device. The method according to any one of claims 1 and 3 to 4,
A surface defect determination device in which three or more lighting devices are arranged on a circumference centered on the line sensor at an angle difference of 360 degrees divided by the number of lighting devices. A plurality of lighting devices arranged at different positions,
A line sensor capable of receiving the reflected light of the illumination light irradiated from each lighting device to the object to be inspected,
moving means for moving the object to be inspected relative to the lighting device and the line sensor;
Illumination control means for switching the illumination light from each lighting device one by one at a predetermined cycle and irradiating it to the object to be inspected;
By the moving means, the inspected object is moved relative to the lighting device and the line sensor, and by the lighting control means, each time the illumination light from each lighting device is switched, reflected light from the inspected object is received. Line sensor control means for controlling the line sensor to perform imaging;
An external inspection device comprising the surface defect determination device according to any one of claims 1 and 3 to 4. As a program stored on a recording medium,
The above program:
When the object to be inspected is moved relative to the lighting devices and line sensors arranged at different positions, the illumination light from each lighting device is switched one by one to irradiate the object to be inspected, each time the illumination light from each lighting device is switched. , an image acquisition step of acquiring a plurality of images in a state of positional deviation corresponding to the conversion of the illumination light by receiving and photographing reflected light from the inspected object with a line sensor;
a positioning step for positioning images corresponding to each lighting device acquired by the image acquisition step;
To cause the computer to execute a determination step for determining surface defects of the object to be inspected from the image aligned by the alignment step,
A part of each pixel of the line sensor is an overlapping area where the shooting range overlaps between the current shooting and the previous shooting due to illumination light from one of the lighting devices being irradiated to the inspection object,
When the part of one pixel excluding the overlapping area is used as a subpixel, the received light amount of the overlapping area is estimated by subtracting the light received amount of the overlapping area from the light received amount of the entire pixel in the current shooting to create a subpixel image. Executing the sub-pixel image production step for producing on the computer,
A program stored in a recording medium that causes the computer to execute, in the positioning step, a process for positioning a subpixel image corresponding to each lighting device produced by the subpixel image production step. delete According to claim 17,
A program stored in a recording medium that causes the computer to execute, in the sub-pixel image creation step, a process of subtracting the received light amount of the overlapping area from the received light amount of the entire pixel while correcting each area. The method of claim 17 or 19,
In the sub-pixel image creation step, the received light amount of the overlapping area is determined from the sum of the received light amounts of the sub-pixels estimated previously, and the obtained light-received amount is subtracted from the light-received amount of the entire pixel to estimate the light-received amount of the current sub-pixel. A program stored on a recording medium that runs on a computer. According to claim 20,
In the sub-pixel image production step, a program stored in the recording medium causes the computer to perform a process of estimating the received light amount of the first sub-pixel as the average value of the received light amount of all the first pixels after the start of shooting, divided by the number of sub-pixels per pixel. . The method of claim 17 or 19,
In the subpixel image production step, if the received light amount of all pixels does not exceed the predetermined threshold, the average value of the received light amount of all pixels divided by the number of subpixels per pixel is estimated as the light received amount of the current subpixel, and the received light amount of all pixels is estimated. A program stored in a recording medium that causes the computer to execute a process of estimating the light reception amount of the current subpixel by subtracting the light reception amount of the overlapping area from the light reception amount of the entire pixel when the received light amount exceeds a predetermined threshold. The method of claim 17 or 19,
In the position alignment step, the position alignment of the subpixel image corresponding to each lighting device produced by the subpixel image production step is performed by correcting the luminance value K ⁱ _j with the correction value ^K'i _j according to the following equation. A program stored on a recording medium that executes on the computer.

However, i: index of subpixel estimated position
j: Identification car number of the light that is on The method of claim 17 or 19,
In the determination step, if the bright points corresponding to each lighting device do not overlap in the subpixel image aligned by the position alignment step and each bright point is within a preset range, there is a concave defect on the surface of the object to be inspected. or a program stored in a recording medium that causes the computer to execute processing for determining that a convex defect exists. According to claim 24,
In the determination step, in the subpixel image aligned by the alignment step, a concave defect exists if the position of the bright spot corresponding to each lighting device is opposite to the arrangement position of the lighting device, and if the reverse is not the case, a concave defect exists. A program stored in a recording medium that causes the computer to execute a process to determine that a convex defect exists. The method of claim 17 or 19,
In the determination step, when bright spots corresponding to each lighting device overlap in the pixel image aligned by the alignment step, the computer performs processing to determine that dust or dirt is present on the surface of the object to be inspected. A program stored on a recording medium that can be executed. The method of claim 17 or 19,
Pixels whose total amount of light exceeds a predetermined threshold are detected as defect candidate pixels, sub-pixel images are aligned for the detected defect candidate pixels by the position alignment step, and further, the judgment step is performed on the surface of the inspected object. A program stored on a recording medium that causes the computer to execute defect determination processing. The method of claim 17 or 19,
A program stored in a recording medium in which an LED or a visible semiconductor laser is used as a light source of the lighting device. The method of claim 17 or 19,
A program stored in a recording medium in which the plurality of lighting devices are arranged at positions of 360 degrees/(number of lighting devices) on a circumference centered on the line sensor.

Images