JP5992315B2 - Surface defect detection device and surface defect detection method - Google Patents

Description

  The present invention relates to a surface defect detection apparatus and a surface defect detection method for measuring and inspecting uneven defects such as scratches generated on the surface of an object having a uniform shape by using an optical cutting method.

  As a method for measuring the surface shape of the object to be measured, slit light is applied obliquely to the optical axis of the camera, and the three-dimensional shape of the light section image formed on the surface of the object to be measured using the triangulation principle. The light cutting method to measure is used. The height of the object to be measured is measured by measuring the distance to the position of the line laser light image corresponding to the object to be measured, with the position of the line laser light image corresponding to the captured ideal shape surface (reference surface) as the zero reference. An apparatus and a method for measuring the above are disclosed (for example, Patent Document 1).

Japanese Patent Laid-Open No. 7-63518 (paragraphs [0016] to [0024], FIG. 1)

In general, with the optical cutting method, only one line can be measured with a single measurement. However, when surface defects are detected, the surface shape often needs to be measured at the maximum and minimum positions. It is necessary to measure without leakage.
Further, in the disclosed invention of Patent Document 1, it is necessary to measure the surface shape with reference to an ideal shape having no defect, but there is no guarantee that the ideal shape surface is imaged during one imaging period, and the reference cannot be set, There is a problem that the defect cannot be measured.

  The present invention has been made to solve the above-described problems, and calculates the maximum position and the minimum position of the unevenness on the surface of the object to be inspected with the ideal shape calculated from the imaged optical cutting line as the zero reference. An object of the present invention is to provide a surface defect detection device and a surface defect detection method that can be performed.

A surface defect detection apparatus according to the present invention includes a linear light generator that irradiates an inspection object with linear light from an oblique direction, and a camera that captures an optical cutting line formed on the inspection object by the linear light. An inspection object moving device that moves the inspection object, and an image processing device that detects a surface defect from the captured image. The exposure time of the camera is set to one frame time determined from the frame rate of the camera, and imaging is performed. For each column in the line width direction of the optical cutting line of the captured image, the position where the luminance value first exceeds the threshold from the vertical direction of the captured image is detected, and the maximum position in the line width direction of the optical cutting line, Measure the location of the minimum position, calculate the ideal shape from the maximum position and minimum position data of the optical cutting line in the line width direction, and calculate the maximum position and minimum position data of the optical cutting line in the line width direction From the ideal shape of the surface to be inspected Large position, in which a configuration of calculating the minimum position.

A surface defect detection method according to the present invention includes a linear light generator that irradiates an inspection object with linear light, a camera that images a light cutting line formed on the inspection object by linear light, and an inspection An irradiation step of irradiating the inspection object with oblique light from an oblique direction using a surface defect detection apparatus including an inspection object moving device that moves an object and an image processing device that detects a surface defect from a captured image; A scanning process of moving the inspection object and scanning the optical cutting line, an imaging process of imaging the optical cutting line by setting the exposure time of the camera to one frame time determined from the frame rate of the camera, and the captured imaging For each column in the line width direction of the optical cutting line of the image, the part where the luminance value first exceeds the threshold from the vertical direction of the captured image is detected, and the maximum and minimum positions in the line width direction of the optical cutting line And measure the maximum in the width direction of the measured optical cutting line. A first image that calculates an ideal shape from the position and minimum position data, and calculates the maximum and minimum positions of unevenness on the surface of the object to be inspected from the maximum position and minimum position data in the line width direction and the calculated ideal shape. This includes a generation process and a determination process for detecting and determining defects on the surface of the inspection object.

  Since the surface defect detection device according to the present invention is configured as described above, the maximum position and the minimum position of the unevenness on the surface of the object to be inspected are calculated based on the ideal shape calculated from the imaged optical cutting line. It is possible to provide a surface defect detection apparatus that can perform the above-described process.

  Since the surface defect detection method according to the present invention includes the steps as described above, the maximum position and the minimum position of the unevenness on the surface of the object to be inspected are calculated based on the ideal shape calculated from the imaged optical cutting line. It is possible to provide a surface defect detection method capable of

It is a block diagram which concerns on the surface defect detection apparatus of Embodiment 1 of this invention. It is a figure which shows the example of the captured image which concerns on the surface defect detection apparatus of Embodiment 1 of this invention. It is explanatory drawing of the maximum and minimum position detection method of the line | wire width direction of the optical cutting line which concerns on the surface defect detection apparatus of Embodiment 1 of this invention. It is explanatory drawing of the defect detection method which concerns on the surface defect detection apparatus of Embodiment 1 of this invention. It is explanatory drawing of the positional relationship of the camera which concerns on the surface defect detection apparatus of Embodiment 1 of this invention, and linear light. It is explanatory drawing of the height calculation method by the optical cutting method which concerns on the surface defect detection apparatus of Embodiment 1 of this invention. It is explanatory drawing of the position detection correction method of the line longitudinal direction of the optical cutting line which concerns on the surface defect detection apparatus of Embodiment 1 of this invention. It is a figure of the cross-sectional shape of the longitudinal direction of the to-be-inspected object which concerns on the surface defect detection apparatus of Embodiment 2 of this invention. It is explanatory drawing of the relationship between each imaging period and the luminance value in a captured image which concerns on the surface defect detection apparatus of Embodiment 2 of this invention. It is a flowchart which concerns on the surface defect detection method of Embodiment 3 of this invention.

Embodiment 1 FIG.
The first embodiment includes a linear light generation device, a camera, an inspected object moving device, and an image processing device, takes an image with the maximum exposure time of the camera, and maximizes the optical cutting line in the line width direction. The ideal shape is calculated from the position and minimum position data, and the maximum position and the minimum position of the unevenness on the surface of the object to be inspected are calculated from the maximum position and minimum position data in the line width direction of the light section line and the calculated ideal shape. The present invention relates to a configured surface defect detection apparatus.

  Hereinafter, regarding the configuration and operation of the surface defect detection device 1 according to the first embodiment of the present invention, FIG. 1 which is a configuration diagram of the surface defect detection device, FIG. 2 which shows an example of a captured image, a detection method, a calculation method, and the like This will be described with reference to FIGS.

FIG. 1 shows a configuration relating to a surface defect detection apparatus 1 according to Embodiment 1 of the present invention.
In FIG. 1, the surface defect detection device 1 includes a linear light generator 2, a camera 4, an image processing device 5, an inspection object 6, and an inspection object moving device 7. The linear light 3 output from the linear light generator 2 is applied to the inspection object 6 from an oblique direction. When the linear light 3 is irradiated, a light cutting line 10 is formed on the inspection object 6, and the light cutting line 10 is imaged by the camera 4. The image processing device 5 processes the imaged data of the optical cutting line 10 to detect a defect on the inspection object 6.

  The inspected object 6 has a uniform surface shape, and has the same shape in the longitudinal direction, such as a plate material or a cable. When the linear light 3 output from the linear light generator 2 is irradiated at an inclination angle with respect to the longitudinal direction of the inspection object 6 in order to measure the surface shape of the inspection object 6, the surface of the inspection object 6 The optical cutting line 10 is formed. Here, the linear light generating device 2 uses a cylindrical lens or the like in the illumination light such as laser light or halogen illumination to narrow the line width direction, or uses a polygon mirror or the like as a point light source using a laser or the like. Then, a linearly radiated irradiation direction is used.

  Since the linear light 3 irradiated to the inspection object 6 is irradiated obliquely to the inspection object 6, it is irradiated in the line width direction of the light cutting line 10 according to the unevenness of the surface of the inspection object 6. The position changes. The scattered light of the linear light 3 on the surface of the inspection object 6 is imaged by the camera 4 installed on the inspection object 6, and the image processing apparatus 5 performs arithmetic analysis of the captured image.

The inspection object moving device 7 is a means for moving the measurement position of the inspection object 6 in the longitudinal direction of the inspection object 6, and the linear light 3 is transferred to the inspection object 6 by the inspection object moving device 7. The irradiated position can be moved and continuously measured.
The inspection object moving device 7 has a different configuration depending on the type of the inspection object 6, and an XY robot capable of moving in a plane is a moving means if it is a plate material. Further, if the inspection object 6 is a cable, it can be wound up by a drum and a drum rotation mechanism. Further, a holding mechanism (not shown) for the inspection object 6 is installed so that the relative positions of the camera 4, the linear light generator 2, and the inspection object 6 do not change during the movement. When the inspected object 6 is a cable, the vertical and horizontal misalignment can be suppressed by using the V roller as a holding mechanism.

FIG. 2 shows an example of an image obtained by capturing the linear light 3 irradiated to the inspection object 6 with the camera 4. FIG. 2A is an image when there is no defect on the surface, and FIG. 2B is an image when there is a dent due to a defect on the surface.
Since the inspected object 6 has a uniform surface shape, even if the inspected object 6 is moved using the inspected object moving device 7, the surface shape does not change. Further, since the linear light 3 irradiates the inspection object 6 from an oblique direction, as shown in FIG. 2A, when the inspection object 6 has a cylindrical shape such as a cable, An image of the arc-shaped linear light 3 can be taken as the light cutting line 10.

  On the other hand, when there is an uneven defect on the surface, the position of the light cutting line 10 changes due to the unevenness of the surface while one image is captured by the camera 4. Since one image has an integral value within the imaging time, the blurring portion 11 as shown in FIGS. 2B and 2B, or FIG. The duplex portion 12 as shown in b-2) can be imaged. This is because the height change of the surface of the inspection object 6 within the imaging time is such that the upper end 13 of the optical cutting line (hereinafter referred to as upper end 13 as appropriate) and the lower end 14 of the optical cutting line (hereinafter referred to as lower end 14 as appropriate). It has changed within the range of

In the surface defect detection device, it is often necessary to detect the heights of the upper end 13 and the lower end 14 of the optical cutting line 10, but when the optical cutting line 10 is discretely imaged with a high-speed shutter, the measurement positions are also discrete. Therefore, the maximum and minimum heights of the surface of the inspection object 6 cannot be measured.
On the other hand, by imaging the blur portion 11 and the duplex portion 12 as shown in FIG. 2B, it becomes possible to image the entire surface of the inspection object 6, and to measure the maximum and minimum height of the surface. Can do.
In addition, when the height of the inspection object 6 is gradually changed while the image of the single light cutting line 10 is being picked up, the picked-up portion 11 is picked up as shown in FIGS. 2B and 2B-1. The When the height of the inspection object 6 changes sharply, an image is taken as a duplex portion 12 as shown in FIGS.

Here, a method of detecting the positions of the upper end 13 and the lower end 14 from an image obtained by capturing the blurred portion 11 will be described with reference to FIG.
FIG. 3 is an explanatory diagram of a method for detecting the maximum and minimum positions of the light cutting line 10 in the line width direction. FIG. 3A shows an example of an image in which the blurred portion 11 is imaged, and FIG. 3B shows an example of the jth column in which the blurred portion 11 is imaged. Show.
In this image, the inspection object 6 is a cylindrical shape like a cable. The lower side of the image is the inside of the cable, and the upper side of the image is the outside of the cable. And the part of the optical cutting line 10 becomes a cable surface.

  FIG. 3B shows a luminance value distribution (luminance profile) with respect to the pixel position in the row direction of the j-th column in FIG. The portion where the blurred portion 11 is imaged has a high luminance, and the other portions are not irradiated with the linear light 3, so the luminance is low. For this reason, by setting a threshold value and detecting a portion (for example, the i-th row) exceeding the threshold brightness from the vertical direction of the image, the maximum and minimum positions of the inspection object 6 irradiated with the linear light 3 are detected. It becomes possible to measure the location.

  In addition, since the brightness | luminance of the location where the linear light 3 with low brightness | luminance is not irradiated is measurable as an initial value (in this case, about 10 digits), a threshold value is set to about 20 digits, and the brightness | luminance beyond it is shown. The part is detected as the surface of the cable irradiated with the linear light 3.

Since the change in the vertical direction of the light section line image is a change in the height direction of the surface of the inspection object 6, the unevenness of the surface of the inspection object 6 is calculated from the image including the blurring portion 11.
FIG. 4A shows an acquired shape of the lowermost end portion of each column acquired from the image including the blurred portion 11. Originally, since the cable of the inspection object 6 has a cylindrical surface, the surface shape of the inspection object 6 is a broken line shape indicated by an ideal shape. For this reason, as shown in FIG. 4B, the difference value between the acquired shape and the ideal shape becomes unevenness generated on the surface of the inspection object 6.
For this difference value, an allowable range is determined in consideration of the roughness of the surface of the inspection object 6, and a portion exceeding this allowable range is determined as a defect of the inspection object 6.

FIG. 5 illustrates the positional relationship between the camera 4 and the linear light 3, that is, the layout of the camera 4 and the linear light 3 and the setting of the coordinate system.
Hereinafter, a height measurement method based on the principle of triangulation will be described with reference to FIG. 6 which is an explanatory diagram of a height calculation method by a light cutting method. FIG. 6 shows FIG. 5 in the yz plane. The height at which the center of the optical axis of the camera 4 intersects the linear light 3 is Z0, the irradiation angle of the linear light 3 is θ, the focal length of the lens of the camera 4 is f, and the distance from the camera 4 to the inspection object 6 Is f ′, the relationship between the height of the inspection object 6 and the imaging position of the camera is expressed by the following equation (1).

Next, correction when a telecentric lens is not used as the lens of the camera 4 will be described.
As shown in FIG. 7 which is an explanatory view of the position detection correction method in the longitudinal direction of the optical cutting line 10, when a telecentric lens is not used as the lens of the camera 4, the height of the inspection object 6 is increased due to the influence of the angle of view. Accordingly, the position of the linear light 3 in the longitudinal direction changes. FIG. 7 shows FIG. 5 in the xz plane, and is obtained by rotating FIG. 6 about the z axis by 90 °. X0 is the center of the image sensor inside the camera in the x-axis direction, and X0 ′ is the intersection of the linear light 3 and the straight line drawn from X0 in the z-axis direction.
Specifically, when the left-right direction in FIG. 7 is the longitudinal direction of the linear light 3, everything on the line connecting X 2 -X ′ 2 is imaged by the camera at X 2, so the linear light 3 In order to measure the position in the longitudinal direction, it is necessary to measure the height Z (y) from the relationship shown in FIG.

Further, as shown in FIG. 4, in order to measure the depth of the scratch, the amount of change from the virtual surface is obtained. In the case of the cylindrical inspection object 6 like a cable, since the cross section is circular, a circle can be used as the virtual surface. Then, a portion other than the unevenness of the surface shape of the cable acquired from the circle and the light cut image is fitted with the circle.
In the circle fitting using the least square method including the unevenness, the fitting is affected by the unevenness and an error occurs in the fitting. Therefore, as a method not affected by unevenness, circle fitting is performed by the LMedS (LEAST MEDIAN OF SQUARES) method using random sampling.
The LMedS method performs estimation using the following formula (3).

  Here, min indicates a minimum value and med indicates a median value. The difference between the estimated value and the reference value is applied to ε. That is, an estimated value with the smallest median value is adopted from a plurality of estimation results. In the estimation method using this criterion, since the median value is used, even if 50% of all data is an exceptional value, there is no significant deviation from the true value. Furthermore, the estimation when the number of parameters to be estimated is large is facilitated by using random sampling, and the minimum required number of estimations q can be obtained from the following equation (4).

  Here, P is the probability that at least one sampling does not include an exceptional value, α is the ratio of exceptional values in all data, and β is the number of samplings required for one estimation. In the case of circle fitting by the LMedS method, α = 0.5 and β = 3. Therefore, if P = 0.993, it is necessary to repeat 40 times or more.

When this LMedS method is used, circular fitting can be performed if the range of exceptional values (here, cable surface scratches) is 50% or less of the measurement range.
In the circle fitting using the LMedS method, first, three points {(x ₁ , y ₁ ), (x ₂ , y ₂ ), (x ₃ , y ₃ )} are randomly extracted from the coordinates of the surface shape of the cable. By solving the following simultaneous equations (5), the center coordinates (x ₀ , y ₀ ) and the radius r of the fitting circle are obtained.

Then, a circle shape y ^ (x) is obtained from the previous parameters (x ₀ , y ₀ , r) using Equation (6), and the fitting circle is evaluated using Equation (7) using the LMedS criterion.

  However, y (x) is the surface shape of the cable.

  Repeat the above to obtain the best fitting circle. By calculating the difference between the circle and the surface shape of the object 6 to be inspected, the depth of the unevenness is calculated.

  Thus, although the detailed shape during the exposure time cannot be obtained from the light cutting line 10 imaged according to the present invention, the lowest shape and the highest shape can be obtained, so that the ideal shape of the inspection object is in the moving direction. In the case of a uniform shape, it is possible to detect a shape abnormality on the entire inspection object.

Note that the range in which one image is captured is determined by the frame rate of the camera and the moving speed of the inspection object 6.
For example, assuming that the frame rate of the camera is 100 frames / second and the moving speed of the inspection object 6 is 10 mm / second, the range of imaging with one image is as follows:
10 mm / second × (1/100 frame / second) = 0.1 mm / frame. Therefore, since the inspected object 6 is a continuous body, the process of 0.1 mm is continuously performed.

  As described above, the surface defect detection device 1 according to the first embodiment includes the linear light generation device, the camera, the inspection object moving device, and the image processing device, and maximizes the exposure time of the camera. The ideal shape is calculated from the data of the maximum position and minimum position in the line width direction of the optical section line, and the maximum position and minimum position data in the line width direction of the optical section line and the calculated ideal shape The maximum position and the minimum position of the unevenness on the surface are calculated. Therefore, it is possible to calculate the maximum position and the minimum position of the unevenness on the surface of the object to be inspected based on the ideal shape calculated from the imaged light section line, and to easily detect defects on the surface of the object to be inspected. . Thereby, it is possible to prevent a defect on the surface of the inspection object from being overlooked.

  Further, defects on the surface of the object to be inspected can be easily detected, and the defects can be prevented from being overlooked, so that the product can be used for a long time and the yield can be improved.

Embodiment 2. FIG.
The surface defect detection apparatus according to the second embodiment is further configured to calculate the height distribution of the surface of the inspection object from the luminance distribution in the line width direction of the light section line.
Hereinafter, regarding the operation of the surface defect detection apparatus according to the second embodiment, FIG. 8 is a diagram of a cross-sectional shape in the longitudinal direction of the inspection object 6, and is an explanatory diagram of the relationship between each imaging period and the luminance value in the captured image. 9 will be described.
The configuration of the surface defect detection apparatus of the second embodiment is the same as that of FIG. 1 described in the first embodiment.

In the first embodiment, the maximum and minimum positions of the inspection object 6 are measured by detecting the upper end 13 and the lower end 14 of the light cutting line from the image including the blur portion 11 as shown in FIG. As can be seen from FIG. 3B, the luminance distribution at the location exceeding the threshold value correlates with the height distribution of the surface of the inspection object 6.
In the case of FIG. 3B, the height change of the inspection object 6 during the main image capturing period is the highest in the area corresponding to the pixel position 200, and thereafter the area corresponding to about 300 in height. Is almost evenly distributed.

For example, assume that the cross-sectional shape in the longitudinal direction of the inspection object 6 is a shape as shown in FIG. (T1) to (t5) in FIG. 8 indicate positions in the longitudinal direction of the inspection object 6, and a case where each range is captured as one image will be described.
In the periods (t1), (t4), and (t5), the height does not change within each imaging period and is constant. In the period (t2), the height gently changes during the imaging period. In the period (t3), the height changes stepwise from the middle.
Here, when the z direction, that is, the surface of the inspection object 6 changes in the height direction, the position where the linear light 3 on the captured image is projected in the y axis direction changes as shown in FIG. It can be measured as a change in height.

  Since one image is an integral value of light received by the camera 4 within the exposure time, the image when the projection position of the linear light 3 changes within the imaging period of one image is at a specific height. Imaging is performed as a luminance value proportional to the irradiation time.

FIG. 9 shows the relationship between the height direction of the inspection object 6 and the luminance value in the captured image in each imaging period.
In the periods (t1), (t4), and (t5), since the height does not change and is constant within each imaging period, the luminance distribution is concentrated at a position where the height is 0.
In the period (t2), since the height gently changes during the imaging period, there are peaks at the heights 0 and z1, and the luminance is evenly distributed between the heights 0 and z1.
In the period (t3), the height changes stepwise from the middle, so there is a peak at the height 0 and z1, but no luminance is generated between the height 0 and z1 as in the period (t2). .

  As described above, since the luminance value of the captured image is proportional to the irradiation time at a specific height, when the inspection object moving device 7 moves at a constant speed, the length of the specific height within the imaging period is expressed by the formula ( 8).

Here, n is a length that is a specific height in the imaging period, k is a conversion coefficient, v is a moving speed of the inspection object moving device 7, and I is a luminance of an image corresponding to the specific height. Value.
As a result, when unevenness is generated on the surface of the inspection object 6, it is possible to determine the height distribution. Thereby, for example, the length of a convex part can be added as a criterion.

  As described above, the surface defect detection apparatus according to the second embodiment is further configured to calculate the height distribution of the surface of the inspection object from the luminance distribution in the line width direction of the light section line. Therefore, in addition to the effects of the first embodiment, the use of the height distribution on the surface of the inspection object as a determination criterion can further prevent the inspection surface from overlooking defects.

Embodiment 3 FIG.
The surface defect detection method of the third embodiment is ideal from the irradiation process, the scanning process, the imaging process, and the data of the maximum position and the minimum position in the line width direction using the surface defect detection apparatus 1 of the first embodiment. A first image generation step of calculating a shape and calculating a maximum position and a minimum position of unevenness on the surface of the object to be inspected from the data of the maximum position and minimum position in the line width direction and the calculated ideal shape; This comprises a second image generation process for calculating the height distribution of the surface of the inspection object from the luminance distribution in the line width direction, and a determination process for detecting and determining defects on the surface of the inspection object.
Hereinafter, the surface defect detection method according to the third embodiment will be described with reference to FIG. 1 which is a configuration diagram of the surface defect detection apparatus 1 and each explanatory diagram of the first and second embodiments, based on the flowchart of FIG.

When the process is started, first, in step 1 (S1), the inspection object 6 is irradiated with the linear light 3 from an oblique direction (irradiation process).
Next, in step 2 (S2), the inspection object 6 is moved and the light cutting line 10 formed on the inspection object 6 is scanned (scanning process).
Next, in step 3 (S3), the optical cutting line 10 is imaged while maximizing the exposure time of the camera (imaging process).
Next, in step 4 (S4), the ideal shape is calculated from the maximum position and minimum position data of the optical cutting line 10 in the line width direction, and the maximum position and minimum position data of the optical cutting line 10 in the line width direction are calculated. The maximum position and the minimum position of the unevenness on the surface of the inspection object 6 are calculated from the calculated ideal shape (first image generation step).
Next, in step 5 (S5), the height distribution of the surface of the inspection object 6 is calculated from the luminance distribution in the line width direction of the light cutting line 10 (second image generation step).
Next, in step 6 (S6), the surface defect of the inspection object 6 is detected and determined (determination step).

  In the description of the surface defect detection method according to the third embodiment, the second image generation step is performed following the first image generation step. However, only the first image generation step is performed, and the inspection object 6 It is also possible to detect and determine surface shape defects by only calculating the maximum and minimum positions of the surface irregularities. If the second image generation step is performed to calculate the height distribution of the surface of the inspection object 6 and use it for detection and determination of defects, detection omission can be prevented more.

  As described above, the surface defect detection method according to the third embodiment includes an irradiation process, a scanning process, an imaging process, a first image generation process, a second image generation process, and a determination process. Based on the ideal shape calculated from the cutting line, the maximum and minimum positions of irregularities on the surface of the inspection object are calculated, and the height distribution of the surface of the inspection object is calculated. Therefore, it is possible to easily detect the defect on the surface of the inspection object, and to prevent the defect on the surface of the inspection object from being overlooked.

  In the present invention, the embodiments can be appropriately modified and omitted within the scope of the invention.

1 surface defect detector, 2 linear light generator, 3 linear light, 4 camera,
5 image processing device, 6 inspection object, 7 inspection object moving device, 10 optical cutting line,
11 Blur part, 12 Duplicated part, 13 Upper end of optical cutting line, 14 Lower end of optical cutting line.

Claims (3)

A linear light generator for irradiating the inspection object with linear light from an oblique direction, a camera for imaging a light cutting line formed on the inspection object by the linear light, and the inspection object are moved. An inspection object moving device, and an image processing device for detecting a surface defect from a captured image,
The exposure time of the camera is imaged for one frame time determined from the frame rate of the camera, and from the vertical direction of the captured image for each column that is the line width direction of the optical cutting line of the captured image. First, the location where the luminance value exceeds the threshold is detected, the maximum position in the line width direction of the light cutting line, the position of the minimum position is measured, the maximum position in the line width direction of the measured light cutting line, the minimum The ideal shape is calculated from the position data, and the maximum position and the minimum position of the unevenness on the surface of the object to be inspected are calculated from the maximum position and minimum position data in the line width direction of the light cutting line and the calculated ideal shape. A surface defect detection device configured. The surface defect detection apparatus according to claim 1, wherein the threshold is determined from a luminance of a portion of the captured image that is not irradiated with the linear light. A linear light generator for irradiating the inspection object with linear light, a camera for imaging a light cutting line formed on the inspection object by the linear light, and an inspection object for moving the inspection object Using a surface defect detection device comprising a moving device and an image processing device for detecting a surface defect from a captured image,
An irradiation step of irradiating the inspection object with the linear light from an oblique direction;
A scanning step of moving the inspection object and scanning the optical cutting line;
An imaging step of imaging the optical cutting line with an exposure time of the camera for one frame time determined from a frame rate of the camera;
For each column in the line width direction of the optical cutting line of the imaged image that has been imaged, detect the location where the luminance value first exceeds the threshold from the vertical direction of the captured image, and then the line width direction of the optical cutting line Measuring the position of the maximum position, the minimum position, calculating the ideal shape from the maximum position in the line width direction of the measured optical cutting line, the data of the minimum position, the maximum position in the line width direction of the optical cutting line, A first image generation step of calculating a maximum position and a minimum position of the unevenness of the surface of the object to be inspected from the data of the minimum position and the calculated ideal shape;
A determination step of detecting and determining defects on the surface of the inspection object;
A surface defect detection method comprising:

Images