JP7621789B2 - Inspection device, inspection lighting device, inspection method, and article manufacturing method - Google Patents

Description

The present invention relates to an inspection device that illuminates an object with light and detects the surface characteristics, scratches, defects, etc. of the object.

Evaluating the appearance of an object has long been an important task, and in recent years, automation has been promoted in the inspection of the finish of automobiles and other industrial products. In particular, the following technology has been disclosed for inspecting parts with surfaces with complex irregularities, which uses lighting and cameras to automatically inspect the parts.

For example, Patent Document 1 describes a method in which the tooth surface is illuminated with a uniform light installed above the gear, and the gear to be inspected is rotated while imaging and processing the images of the tooth surface every 1/n pitch. This allows an inspection device to be disclosed that can detect defects on the top or side of the gear without overlooking them, even if they are difficult to see.

Furthermore, Patent Document 2 discloses a technology for inspecting an object having a curved portion for defects by illuminating the object with a line pattern light, moving the illumination unit according to the curved portion, and appropriately illuminating the object surface with various irregularities.

JP 2020-38066 A JP 2018-59883 A

However, even with the methods described in the above Patent Documents 1 and 2, it is difficult to inspect an object having a complex shape including recessed portions.
An object of the present invention is to provide an inspection apparatus capable of inspecting objects with complex shapes with high accuracy.

An inspection apparatus according to one aspect of the present invention comprises:
1. An inspection device for inspecting an evaluation surface of an object by acquiring a plurality of images of different phases by imaging an image of a reflected image of the pattern light from the evaluation surface with an imaging unit while shifting the spatial phase of a bright portion and a dark portion of the pattern light irradiated onto the evaluation surface, and using the plurality of images,
evaluating the evaluation surface using a single reflection image based on reflected light reflected only on the evaluation surface and a multiple reflection image based on reflected light reflected by a predetermined surface that is different from the evaluation surface among surfaces constituting the object and is also reflected on the evaluation surface;
The imaging device further comprises a control unit that detects a boundary between the single reflection image and the multiple reflection image by shifting the spatial phase of the pattern light.

The present invention makes it possible to realize an inspection device that can inspect objects with complex shapes with high accuracy.

FIG. 1 is a diagram illustrating a defect inspection device according to a first embodiment. FIG. 2 is a diagram showing a line pattern illumination according to the first embodiment. FIG. 1 is a schematic diagram showing an evaluation surface 41 observed with a single reflection. FIG. 2 is a diagram showing the lighting unit and the camera of the first embodiment as viewed from above. 1 is a diagram showing an example of an image obtained when an evaluation surface 41 of an object 40 is imaged. 4 is a flowchart of a defect inspection of an object surface using the inspection device in the first embodiment. FIG. 13 is a diagram showing the configuration of an inspection device according to a second embodiment. 13 is a diagram showing an example of an image when an evaluation surface 41 is captured by a camera 21 and a camera 22 in the second embodiment. FIG. FIG. 13 is a diagram showing the configuration of an inspection device according to a third embodiment. 13A and 13B are diagrams illustrating a light beam illuminating a recess 43 in the third embodiment.

Below, preferred embodiments of the present invention will be described using examples with reference to the attached drawings. Note that in each drawing, the same members or elements are given the same reference numbers, and duplicate descriptions will be omitted or simplified.

FIG. 1 is a diagram showing an inspection device according to a first embodiment of the present invention.
The line pattern illumination unit 1 is, for example, a surface illumination unit having a highly diffuse light distribution characteristic and consisting of bright and dark areas, and a pattern of the bright and dark areas of the line pattern illumination unit 1 is projected onto an object 4 .

The object 4 to be evaluated is a metal processed part, a resin molded product, or the like, which has a complex shape rather than a simple flat surface, for example a gear shape machined by an NC machine. The evaluation surface on which defect inspection is performed is evaluation surface 41 on object 4, and object 4 has a reflective surface (predetermined surface) 42 that reflects light in addition to evaluation surface 41.

The evaluation surface 41 and the reflecting surface 42 of the object 4 are configured as curved surfaces, for example cylindrical surfaces, and have a curved groove shape.
The inspection device of this embodiment is configured to obtain a first image by directly capturing the reflected light of illumination light directly irradiated from the line pattern illumination unit 1 onto the evaluation surface 41 of the object 4 with a camera serving as an imaging unit capable of acquiring a two-dimensional image.

The light from the line pattern illumination unit 1 is first reflected by the reflecting surface 42, and then the evaluation surface 41 is illuminated with the reflected light. The second image is obtained by capturing the reflected light from the evaluation surface 41 with the camera 2. The two-dimensional first image and second image captured by the camera 2 are input to an image processing unit 5 such as a PC via the control unit 3.

The second image may be obtained by first reflecting the illumination light directly irradiated from the line pattern illumination unit 1 onto the evaluation surface 41 of the object 4 by the reflection surface 42 and then capturing the image with the camera 2. This embodiment is characterized in that a reflection surface (predetermined surface) 42 different from the evaluation surface among the surfaces constituting the object is used, so that a second image different from the first image is obtained from the evaluation surface by the camera.

The image processing unit 5 performs various image processing and various numerical processing for judging defects, and judges the presence or absence of defects and pass/fail. The display unit 6 can display the captured images, the results of numerical processing by the image processing unit 5, and the pass/fail result of defects judged using the results.
The camera 2 is configured by combining a two-dimensional area sensor (imaging sensor) capable of acquiring a two-dimensional image, such as a CCD or CMOS, with a lens, and is capable of acquiring images of the evaluation surface 41 and the reflecting surface 42 .

The camera 2 may be configured by arranging multiple line sensors two-dimensionally. The image processing unit 5 processes the images acquired by the camera 2, and converts the size, depth, and visual prominence of scratches and defects on the evaluation surface 41 into numerical values, and can make a pass/fail judgment, etc.

FIG. 2 is a diagram showing a line pattern of the line pattern illumination unit of the first embodiment.
In FIG. 2, the line pattern illumination unit 1 is configured as a surface illumination unit that can arbitrarily arrange the period and direction of the light and dark parts of the line pattern on a plane.
That is, for example, a surface illumination light source with almost uniform brightness is constructed by placing a diffusion plate on a large number of LED light sources arranged in a two-dimensional manner.Furthermore, a transmission type spatial modulation element whose transmittance can be modulated for each minute area like a black and white liquid crystal panel is placed on top of that (on the front side).The brightness of each of the large number of LEDs arranged in a two-dimensional manner can be adjusted independently.

At least one of the pitch, brightness, contrast, and line direction of the line pattern of the line pattern illumination unit 1 can be arbitrarily adjusted by an adjustment unit of a transmissive spatial modulation element such as a black-and-white liquid crystal panel. Here, the illumination unit is configured to have an illumination area 11 in which transmissive sections (bright sections) 1A and non-transmissive sections (dark sections) 1B are alternately arranged with a period p1, and an illumination area 12 in which bright sections 1C and dark sections 1D are alternately arranged with a period p2. The bright sections of the line pattern illumination unit 1 have a maximum luminance of 3000 cd/m2 ^or more in order to shorten the inspection time.

Next, FIG. 3 is a schematic diagram of an evaluation surface 41 observed with a single reflection, and the characteristics of the evaluation surface 41 etc. will be described with reference to FIG.
3A , when the camera 2 is placed in a position where it can capture the line pattern reflected once by the evaluation surface 41B close to the line pattern illumination unit 1 of the evaluation surface 41, the line pattern illumination does not strike the evaluation surface 41A close to the camera 2 among the evaluation surfaces 41. In addition, the line pattern does not enter the camera via the reflection surface 42.

Figure 3 (B) shows a configuration in which camera 2 is positioned so that it can capture the line pattern light reflected once by evaluation surface 41A, the side of evaluation surface 41 that is closer to the camera. In this configuration, camera 2 cannot capture the line pattern light reflected by evaluation surface 41B, the side of evaluation surface 41 that is closer to line pattern illumination unit 1.

In order to evaluate such an evaluation surface 41, in this embodiment, as shown in Figure 4, a camera 2 and a line pattern illumination unit 1 are positioned so that the evaluation surface 41 can be evaluated using light reflected from a reflective surface 42, which is a surface of the object other than the evaluation surface 41 (multiple-reflected light).
FIG. 4 is a diagram showing the lighting unit and the camera of the first embodiment as viewed from above.

That is, for evaluation surface 41B, which is closer to line pattern illumination unit 1, the line pattern of area 11 that is reflected once by evaluation surface 41B is captured. Also, for evaluation surface 41A, which is closer to the camera, the line pattern of area 12 that is reflected twice by evaluation surface 41 and reflection surface 42 is captured.

In this way, areas 12 and 11 with different line patterns are arranged so that they are reflected on evaluation surface 41A and evaluation surface 41B, and the light reflected once or twice from each can be captured by camera 2. Note that areas 11 and 12 may have the same pattern, but by configuring as in this embodiment, the pitch of each pattern can be aligned to a certain extent in the images captured of the reflected light, making the defect detection process easier.

With this configuration, the reflected image of either area 11 or area 12 of the line pattern illumination unit 1 can be projected onto almost the entire surface of the evaluation surface 41, and the reflected light of each line pattern can be captured, making it possible to detect defects over a wide area of the evaluation surface 41.

The camera 2 adjusts the focal position and aperture of the lens so that the entire surface of the evaluation surface 41 is in focus, allowing the entire surface of the evaluation surface 41 to be clearly observed.
In this embodiment, if the length of the evaluation surface (the length in the vertical direction in Figure 4) is, for example, 20 mm and the incident angle α in Figure 4 is, for example, 85°, in order to focus on the entire surface 41 to be evaluated, it is desirable that the focal depth is 20 mm × sin (85°) = 19.9 mm.

On the other hand, to distinguish a 1 mm wide defect on the evaluation surface, when the defect is viewed from the camera direction, it is 1 mm x cos(85°) = 0.087 mm, and it is preferable that the blur tolerance of the optical system is smaller than that. In other words, only a blur of about 50 μm over 19.9 mm in the focal direction of the camera lens is permitted, and in applications where defects are observed in a macro-photography manner, it becomes necessary to narrow the lens aperture considerably.

For this reason, in order to achieve a balance between the inspection time and the imaging time, it is desirable to set the illumination luminance of the bright part of the line pattern illumination unit 1 to, for example, 3000 cd/ ^m2 or more. Note that since the allowable amount of blur changes depending on the minimum allowable size of the flaw to be judged, the aperture value is also changed accordingly.
Furthermore, a Scheimpflug configuration may be used in which the focal plane is tilted from a plane perpendicular to the optical axis of the camera's photographing lens and the image sensor plane are inclined relatively to deepen the focal depth.

This allows the lens aperture to be opened, ensuring that light reaches the imaging sensor even if the illumination brightness of the line pattern illumination unit 1 is lowered or the imaging time is shortened. This makes it possible to reduce the power consumption and heat generation of the line pattern illumination unit 1 and to increase the inspection speed.

In addition, camera 2 is highly sensitive to scratches and defects when in focus, and detection sensitivity and accuracy decrease as the focus becomes blurred. In other words, in order to ensure that defect detection sensitivity is at or above the desired sensitivity and detection accuracy, it is effective to keep the camera within a specified focal depth (detectable depth) from the focal position.

On the other hand, as described above, by configuring the imaging lens and imaging sensor of camera 2 in, for example, a Scheimpflug configuration, with evaluation surface 41 within the focal depth and reflective surface 42 outside the focal depth, it is possible to reduce the detection sensitivity for scratches and defects on reflective surface 42. This makes it possible to detect only scratches and defects on evaluation surface 41 with high sensitivity. The above is effective in improving the quality of defect inspection.

FIG. 5 is a diagram showing an example of an image obtained when an evaluation surface 41 of an object 40 is imaged.
The image obtained by the camera 2 is as shown in Fig. 5. That is, an image (first image) of the evaluation surface 41B is obtained, onto which an illumination image of the light and dark pitch P2 reflected once on the evaluation surface 41 is reflected. Also, an image (second image) of the evaluation surface 41A is reflected onto which an illumination image of the light and dark pitch P1 reflected twice on the reflecting surface 42 and the evaluation surface 41 is reflected side by side on the evaluation surface 41. The light and dark pitch and contrast reflected in each region vary mainly depending on the curvature, surface properties, etc. of the reflecting surface 42. A method for adjusting the difference in the line pattern conditions will be described later.

Next, we will explain how to detect scratches and defects. Images of the line pattern illumination unit 1 with light and dark pitches P1 and P2 are reflected on the evaluation surfaces 41A and 41B, respectively, but here we will explain the case where P1 and P2 are the same. In other words, we do not change the illumination pattern for each evaluation area, and assume that P = P1 = P2.

The line pattern illumination unit 1 can be moved by the driving mechanism 7 shown in FIG. 1 in a direction (the X direction in the figure, the periodic direction of pitches p1 and p2) perpendicular to the line (longitudinal direction) of the transmissive portion 1A and the non-transmissive portion 1B of the line pattern illumination unit 1. The driving mechanism 7 is connected to the control unit 3.

The control unit 3 is configured, for example, by a board having a CPU as a computer and a memory storing a computer program, and synchronously controls the line pattern illumination unit 1, the camera 2, and the drive mechanism 7. The control unit 3 controls the drive mechanism 7 to move the line pattern illumination unit 1 by ΔXi (i = 1, 2, ... N) and cause the camera 2 to capture N images (N > = 3).

Here, ΔXi only needs to be known, so it can be set to any size. However, it is not limited to this configuration, and for example, after manually operating the drive mechanism 7 to move the object 4, the object 4 can be photographed by the camera 2 using a manual trigger.

The inspection device of this embodiment includes an image processing unit 5 that processes the obtained images and a display unit 6. The image processing unit 5 and the display unit 6 are preferably a PC or an LCD display, respectively, but the image processing unit 5 may be a general-purpose PC or a machine dedicated to image processing. The image captured by the camera 2 is transferred to the image processing unit 5 via the control unit.

6 is a flowchart of a defect inspection of an object surface using the inspection device in Example 1. The control unit 3 reads and executes a computer program stored in the memory, thereby controlling the operation of each part of the inspection device as shown in the flowchart of FIG.
The line pattern illumination unit 1 is moved by the driving mechanism 7, and the relative position between the line pattern illumination unit 1 and the object 4 is moved by ΔX1 with respect to the reference position (step S11).

Next, the line pattern illumination unit 1 is illuminated at this position to capture the first image I1(x, y) (step S12). Note that x and y represent pixel positions on the image. Here, when ΔX1 is zero, the first image may be the image at the reference position.
Next, in step S13, it is determined whether i=N (N is a predetermined value N>=3). If the result is No, the process returns to step S11, i is counted up by 1, the line pattern illumination unit 1 is moved by the driving mechanism 7, and the relative position between the line pattern illumination unit 1 and the object 4 is changed by ΔX2 with respect to the reference position (step S11).

Next, the line pattern illumination unit 1 is again illuminated at this position, and the second image I2(x, y) is captured (step S12). This is repeated N times to capture a total of N images. Note that ΔX1, ΔX2, ... ΔXN are each different values. When i becomes N in step S13, proceed to step S14.

Next, a first composite image is generated from the N images using information on the intensity change of the frequency component whose phase shifts by 4πΔXi/P radians when the relative position between the line pattern illumination unit 1 and the object 4 changes by ΔXi (step S14). One example of a composite image is an amplitude image of a frequency component whose phase shifts by 4πΔX1/P radians (if the object is a plane, the frequency component corresponds to a stripe pattern with a period of P/2 that appears on the image). When the relative position between the line pattern illumination unit 1 and the object 4 is shifted in steps of P/N width, ΔXi (i=1, 2, ... N) is expressed by the following formula 1.

ΔXi=(P/N)×(i-1) (Formula 1)
This formula 1 also includes the case where ΔX1 is zero, and when the first image has been displaced from the reference position, the following formula 2 is obtained.
ΔXi=(P/N)×i (Formula 2)
At this time, the amplitude image A(x, y) can be calculated by the following equation 1.

これが、Ｎ枚（Ｎ＞＝３）の画像を処理して被検面の表面の情報を含む処理画像であり、位相が４πΔＸｉ／Ｐラジアンでシフトする周波数成分の強度変化に関する情報を用いて生成された処理画像である。

This is a processed image containing information about the surface of the test surface by processing N images (N>=3), and is a processed image generated using information about the change in intensity of frequency components whose phase is shifted by 4πΔXi/P radians.

When the position of the line pattern illumination unit 1 is moved, the bright points corresponding to the light emitting points of the line pattern illumination unit 1 reflected on the evaluation surface 41 and the dark points corresponding to the dark parts of the line pattern illumination unit 1 also move. Therefore, at one point on the pixel of the camera, the brightness of the intensity changes, and an amplitude corresponding to the difference between the brightness and darkness occurs. Another example of a composite image is a phase image of frequency components whose phase is shifted by 4πΔXi/P radians. The phase image θ(x, y) can be calculated by the following equation 2.
Generally, the phase is calculated from values between -π and π, so if the phase changes beyond this, discontinuous phase jumps will occur in the phase image. For this reason, phase unwrapping is required as necessary.

位相画像では、表面性状として評価面４１と反射面４２の表面の傾きを評価することができ、可視化することもできる。
位相接続（位相アンラップ）には、種々のアルゴリズムが提案されているが、画像ノイズが大きい場合には、誤差が生じうる。位相接続を回避するための手段として、位相の微分に相当する位相差を算出してもよい。位相差Δθｘ（ｘ，ｙ）およびΔθｙ（ｘ，ｙ）は以下の数３により算出できる。

In the phase image, the surface inclination between the evaluation surface 41 and the reflection surface 42 can be evaluated as the surface quality, and can also be visualized.
Although various algorithms have been proposed for phase unwrapping (phase unwrapping), errors may occur when image noise is large. As a means for avoiding phase unwrapping, a phase difference equivalent to the differential of the phase may be calculated. The phase differences Δθx(x,y) and Δθy(x,y) can be calculated by the following Equation 3.

さらなる合成画像の例は平均画像である。平均画像Ｉａｖｅ（ｘ，ｙ）は、以下の式により算出できる。

A further example of a composite image is the average image Iave(x,y) which can be calculated by the following formula:

平均画像では、表面性状として反射率の分布を評価できる。したがって、平均画像では、汚れや錆びなど、正常な部分と反射率に違いがある欠陥の情報を得ることができる。可視化することもできる。このように、振幅画像、位相画像または位相差画像、平均画像で、光学的に評価可能な表面性状が異なる結果、可視化される欠陥も異なるため、これらの画像を組み合わせることで、多様な表面性状を評価して、多様な欠陥を可視化することができる。

The average image can evaluate the distribution of reflectance as the surface quality. Therefore, the average image can obtain information on defects such as dirt and rust, which have a different reflectance from normal areas. It can also be visualized. In this way, the surface quality that can be optically evaluated differs between the amplitude image, phase image or phase difference image, and average image, and as a result, the defects that are visualized also differ. Therefore, by combining these images, it is possible to evaluate various surface quality and visualize various defects.

In this embodiment, a pattern light such as a line pattern is irradiated onto the evaluation surface of the object, and the reflected image of the pattern light from the evaluation surface is captured by a camera while shifting the spatial phase of the light and dark areas of the pattern light. This obtains multiple images with different phases, and the evaluation surface of the object is inspected using these multiple images. At this time, the image is obtained by the imaging unit capturing the reflected light that is reflected by a specific surface (reflective surface 42) that is different from the evaluation surface among the surfaces that make up the object, and is also reflected by the evaluation surface. This allows inspection of the evaluation surface (e.g., inspection for defect detection).

As described above, the brightness and contrast of the light and dark reflected on the evaluation surfaces 41A and 41B in the reflected image are affected by the curvature, reflective properties, and reflectance of the reflecting surface 42.
In defect detection, it is important to keep the brightness and contrast of the stripes reflected on the evaluation surfaces 41A and 41B within a predetermined range in order to perform stable defect detection.

By adjusting the pitch ratio of the line pattern areas 11 and 12 reflected on the evaluation surface 41A and evaluation surface 41B of the evaluation surface 41 using the control unit 3, it is possible to adjust the ratio of p1 and p2 so that P1 and P2 are the same. In addition, by changing the light-dark contrast and brightness of the areas 11 and 12 of the line pattern illumination, it is also possible to adjust the pitch, brightness, and direction of the stripes reflected on the evaluation surface 41.

In this way, by adjusting the pitch, contrast, and orientation of the reflected stripes over the entire surface of evaluation surface 41 using control unit 3, it is possible to optimize the detection sensitivity and S/N ratio for defects over the entire surface of evaluation surface 41. This makes it possible to perform inspection with appropriate inspection parameters, leading to improved inspection quality. Note that the brightness of the image of evaluation surface 41A (first image) and the image of evaluation surface 41B (second image) may also be adjusted by adjusting the gain using control unit 3.

In addition, the boundary 50 of the images with different reflection times (first image and second image) shown in Figure 5 corresponds to an image of reflected light from the edge of the reflecting surface 42, and since the edge has a chamfer or a surface with a high curvature, a clear reflected image of the line pattern cannot be obtained. In addition, the accuracy and sensitivity of the inspection are often deteriorated due to a decrease in the amount of reflected light and an inappropriate pitch of the reflected stripes. Therefore, in this embodiment, the boundary 50 that is set in advance or automatically detected and the surrounding area including the boundary 50 are excluded from the inspection, thereby preventing erroneous detection of scratches.

It is also possible to automatically determine the boundary portion 50 as follows.
Due to the difference in the number of reflections, the movement direction of the line pattern illumination unit 1 reflected in 41A and 41B is opposite to the movement direction of the line pattern illumination unit 1. In other words, when the differential value of the movement direction of the stripes in the phase image is examined, the positive and negative are reversed at the boundary portion 50 of the number of reflections.

Therefore, the control unit 3 can determine that this inverted portion is the boundary 50 based on the change in the differential value, and automatically exclude the boundary 50 (and its surrounding area) that exists in images with multiple different numbers of reflections from the inspection target. In this way, the boundary between the first image and the second image can be detected based on the phase change of the line pattern in the first image and the second image.

In the above embodiment, the pitch and direction of light and dark can be changed by changing the brightness of each part of a transmissive spatial modulation element (e.g., a black-and-white liquid crystal panel) whose transmittance can be adjusted for each minute region. However, it is also possible to prepare multiple line pattern lights with different pitches, brightness, and contrast, and adjust the pitch, brightness, and contrast of the light and dark reflected in each region.

Alternatively, a fixed line pattern illumination with the same light-dark pitch and brightness of the bright areas can be used, so that a line pattern of the same brightness and pitch is reflected in every area regardless of the number of reflections. Even in this case, it is acceptable as long as an image of a level that allows defect detection is obtained even if the image brightness or defect detection sensitivity changes within the evaluation surface 41.

As described above, in the case of line pattern illumination using a transmissive spatial modulation element (e.g., a black and white liquid crystal panel), the illumination light has polarization, so the polarization direction of the line pattern illumination is aligned in a direction other than the P polarization direction relative to the evaluation surface 41 and the reflection surface 42. This allows the camera 2 to capture the image of the line pattern illumination reflected on the evaluation surface 41 with higher contrast.

The above describes the case where pitches P1 and P2 in the images are the same, but even if P1 and P2 are different, the above-mentioned idea can be applied to each evaluation area (41A, 41B) and each evaluation area can be evaluated. In addition, the driving mechanism 7 can be divided into two, and the lighting areas 11 and 12 reflected in each evaluation area can be driven at different speeds by different driving mechanisms, so that the obtained images can be inspected under the same conditions. When one driving mechanism 7 is used, the imaging pitch can be set so that the conditions are met for P1 and P2, respectively.

For example, assuming that defect inspection is performed with the driving mechanism 7 moving a distance of 5 mm for each image capture and seven images taken, the pitch of the light and dark of the lighting is set as p1 = 35 mm and p2 = 17.5 mm. This allows line patterns of different phases to be captured in the seven images captured in each area, enabling appropriate evaluation. A method may be used in which some captured images are not used in one area.

In this embodiment, defect inspection is performed using both the image of line pattern illumination reflected once on the evaluation surface 41 and the image of line pattern illumination reflected twice on the evaluation surface 41 and the reflecting surface 42. However, this is not limited to this, and it is also possible to evaluate only the area where the illumination image reflected multiple times is reflected, or to use an area that includes an image reflected three or more times, depending on the target area to be evaluated.

Fig. 7 is a diagram showing the configuration of an inspection device according to a second embodiment of the present invention. Also, Fig. 8 is a diagram showing an example of an image when the evaluation surface 41 is imaged by the camera 21 and the camera 22 according to the second embodiment. In this embodiment, the imaging unit that images the target object 40 is composed of multiple cameras (camera 21, camera 22) that image the evaluation surface 41 at different angles.

When the evaluation surface 41 is imaged from a different angle in this manner, the position of the boundary between evaluation surface 41A and evaluation surface 41B differs between the image captured by camera 21 (see Figure 8 (A)) and the image captured by camera 22 (see Figure 8 (B)).
Specifically, the boundary (boundary line) moves on the evaluation surface 41, as shown as boundary 50A in the image captured by camera 21 (see Figure 8 (A)), and as boundary 50B in the image captured by camera 22 (see Figure 8 (B)).

As described in the first embodiment, the accuracy of detecting flaws and defects at the boundary (border line) is significantly reduced or cannot be detected. Therefore, the surrounding area including the boundary 50A in the image (see FIG. 8(A)) is inspected using the image of the evaluation surface 41B in the image (see FIG. 8(B)), and the area including the boundary 50B in the image (see FIG. 8(B)) is inspected using the image of the evaluation surface 41A in the image (see FIG. 8(A)). This makes it possible to perform flaw and defect detection on the entire evaluation surface 41 with high accuracy without omissions. In other words, the evaluation surface at a position corresponding to the boundary between the first image and the second image obtained from one of the multiple cameras is inspected using an image obtained from another of the multiple cameras.

Figure 9 is a diagram showing the configuration of an inspection device according to a third embodiment of the present invention. In this embodiment, the illumination used is a transmissive line pattern illumination unit 101, and the object 4 has a concave shape 43 as an evaluation surface, and is placed directly below the transmissive line pattern illumination unit 101. Camera 2 is placed above the transmissive line pattern illumination unit 101 and captures the reflected light of the concave portion 43 on the object surface below via the transmissive line pattern illumination. The evaluation portion on the inner surface of the concave portion 43 has a mixture of portions that reflect once and multiple times, and the reflection directions are also varied.

FIG. 10 is a diagram showing a light beam illuminating the recess 43 in the third embodiment.
As shown in FIG. 10, light from a point 101a on the transmissive line pattern illumination unit 101 is irradiated to a point 43d on the recess 43, and is then reflected by the point 43a and captured by the camera 2 as a light beam CC.
Light from point 101b on the transmissive line pattern illumination unit 101 is irradiated to point 43e on the recess 43, and is then reflected by point 43b and captured by the camera 2 as a light beam DD.

Light from point 101c on the transmissive line pattern illumination unit 101 is irradiated onto point 43c, and is then reflected by point 43c and captured by camera 2 as a light beam EE.
In this way, the light irradiated from each point of the transmission type line pattern illumination unit 101 is reflected once or twice at each point in the recess 43 and then imaged by the camera.

In this embodiment, the transmissive line pattern illumination unit 101 serving as the transmissive pattern illumination unit is configured to widely cover the upper part of the recess 43, so that the recess 43 can be illuminated and imaged in one go using light that has been reflected once or twice on the inner surface of the recess 43. In this way, a transmissive line pattern illumination unit for illuminating the evaluation surface with a line pattern may be provided, and the camera may be configured to image the reflected image from the evaluation surface illuminated by the transmissive line pattern illumination unit via the transmissive line pattern illumination unit.

As described above, the inspection device according to the embodiment of the present invention projects a line pattern onto an evaluation surface of an object, and captures a reflected image of the line pattern from the evaluation surface with a camera while shifting the spatial phase of the light and dark areas of the line pattern, thereby acquiring a plurality of first images with different phases, and inspecting the evaluation surface of the object using the plurality of first images.
The present invention is also characterized in that the camera is configured to acquire a plurality of second images, different from the plurality of first images, from the evaluation surface by using the reflection of a predetermined surface, different from the evaluation surface, among the surfaces that constitute the object.

With this configuration, it is possible to obtain a reflected image by illuminating a line pattern even for an object having an evaluation surface that cannot be equipped with a light and a camera in the regular reflection direction, such as a grooved or concave surface. Also, it is possible to accurately detect the reflection characteristics, shape characteristics, and defects of a wider surface of the object than before. Moreover, by locating the above-mentioned specified surface other than the evaluation surface of the object outside the focal depth, it is possible to obtain only the characteristic data of the evaluation surface and images and information related to scratches, defects, etc.

The system also has a control unit that adjusts, for example, the pattern of the line pattern illumination unit so as to match the brightness of the first image and the second image, the pitch of the line pattern image, etc. Therefore, it is possible to separate the line pattern areas for each number of reflections based on the information of the captured image and the information of the device configuration and the object shape that can be known in advance. In addition, by setting conditions such as brightness correction and line pitch for each area, it is possible to inspect the entire surface of the evaluation surface for defects under the same inspection conditions even for evaluation images that contain a mixture of illumination images with different numbers of reflections.

In addition, by using an inspection illumination that can freely change the brightness for each desired area, at least one of the brightness, direction, and phase of the line pattern illumination or the light and dark pitch of the line pattern illumination is changed for each area. Therefore, it is possible to easily evaluate an evaluation surface that contains a mixture of illumination images with multiple reflections under similar inspection conditions.

Furthermore, a line pattern lighting device is used that can form a line pattern, each of which has two or more lines of light and dark areas arranged alternately, as an illumination surface. At least one of the pitch, luminance, direction, and phase of the line pattern can be changed for each of a plurality of regions of the illumination surface. Furthermore, since the luminance is 3000 cd/m2 or ^more , the inspection efficiency can be improved when the line pattern is used in an inspection device that inspects objects with complex shapes.

Furthermore, by applying the inspection device of this embodiment to a manufacturing system, it is possible to inspect various parts with complex shapes with high precision, thereby improving the reliability and productivity of the manufacturing system that manufactures articles that meet specified standards.
That is, for example, in a manufacturing system, an inspection process using the inspection device of the embodiment can be provided to accurately inspect parts with complex shapes for defects and surface characteristics such as surface shape and surface roughness. Therefore, by carrying out the above-mentioned inspection process on parts with complex shapes, it becomes possible to select non-defective parts with fewer defects than before, and the efficiency of the selection process can be improved.

Then, by using the non-defective parts selected by the sorting process, for example by performing an assembly process, it is possible to finally manufacture an article such as a machine with high precision. In addition, by displaying the measurement data and the images obtained by the inspection device of the embodiment on a display unit such as a monitor, it is possible to grasp the cause of defects in the entire processing steps of the production process, etc., thereby increasing the yield and improving production efficiency. In other words, by using the inspection device of this embodiment, it is possible to increase the manufacturing precision and efficiency of articles.

The present invention has been described in detail above based on its preferred embodiments, but the present invention is not limited to the above embodiments, and various modifications are possible based on the gist of the present invention, and these modifications are not excluded from the scope of the present invention.
A computer program for implementing all or part of the control in this embodiment may be supplied to the inspection device via a network or various storage media. Then, a computer (or a CPU, MPU, etc.) in the inspection device may read and execute the program. In this case, the program and the storage medium storing the program constitute the present invention.

Reference Signs List 1 Line pattern illumination unit 2 Camera 3 Control unit 4 Object 5 Image processing unit 6 Display unit 7 Driving mechanism 41 Evaluation surface 42 Reflection surfaces AA, BB Illumination light beam

Claims (14)

1. An inspection device for inspecting an evaluation surface of an object by acquiring a plurality of images of different phases by imaging an image of a reflected image of the pattern light from the evaluation surface with an imaging unit while shifting the spatial phase of a bright portion and a dark portion of the pattern light irradiated onto the evaluation surface, and using the plurality of images,
evaluating the evaluation surface using a single reflection image based on reflected light reflected only on the evaluation surface and a multiple reflection image based on reflected light reflected by a predetermined surface that is different from the evaluation surface among surfaces constituting the object and is also reflected on the evaluation surface;
An inspection device comprising: a control unit that detects a boundary between the single reflection image and the multiple reflection image by shifting the spatial phase of the pattern light. The inspection device according to claim 1, characterized in that the inspection includes a defect inspection of the evaluation surface. The inspection device according to claim 1 or 2, characterized in that the evaluation surface is placed within the focal depth of the imaging unit, and the predetermined surface is placed outside the focal depth. The inspection device according to any one of claims 1 to 3, characterized in that the imaging unit has a Scheimpflug configuration. The inspection device according to claim 1, characterized in that the boundary between the single reflection image and the multiple reflection image is excluded from the inspection. The inspection device according to any one of claims 1 to 5, characterized in that the imaging unit includes multiple cameras that capture images at different angles. The inspection device according to claim 6, which cites claim 1, is characterized in that the inspection is performed on the evaluation surface at a position corresponding to the boundary between the single reflection image and the multiple reflection image obtained from one of the multiple cameras, using the image obtained from another of the multiple cameras. The inspection device according to claim 1, characterized in that it has a control unit that adjusts the brightness of the single reflection image and the multiple reflection image. The inspection device according to any one of claims 1 to 8, characterized in that it has a line pattern illumination unit for illuminating the evaluation surface with a line pattern, and the line pattern illumination unit has an adjustment unit for adjusting at least one of the pitch, brightness, and direction of the line pattern. The inspection device according to claim 9, characterized in that the adjustment unit adjusts the pattern of the line pattern illumination unit so as to match the pitch of the line pattern image in the single reflection image and the multiple reflection image. The inspection device according to claim 1 , wherein the control unit detects a boundary between the single reflection image and the multiple reflection image based on a phase change of the pattern light in the single reflection image and the multiple reflection image. The inspection device according to any one of claims 1 to 11, characterized in that it has a transmissive pattern illumination unit for irradiating the evaluation surface with the pattern light, and the imaging unit is arranged to capture an image of the reflection from the evaluation surface illuminated by the transmissive pattern illumination unit through the transmissive pattern illumination unit. 1. An inspection method for inspecting an evaluation surface of an object, comprising: acquiring a plurality of images of different phases by capturing an image of a reflected image of a pattern of light irradiated onto the evaluation surface of the object while shifting a spatial phase between a bright portion and a dark portion of the pattern of light irradiated onto the evaluation surface of the object; and inspecting the evaluation surface of the object using the plurality of images,
evaluating the evaluation surface using a single reflection image based on reflected light reflected only on the evaluation surface and a multiple reflection image based on reflected light reflected by a predetermined surface that is different from the evaluation surface among surfaces constituting the object and is also reflected on the evaluation surface;
An inspection method comprising the step of detecting a boundary between the single reflection image and the multiple reflection image by shifting a spatial phase of the pattern light. An inspection step of inspecting the object using the inspection device according to any one of claims 1 to 12;
and manufacturing the article by processing the object based on the results of the inspection in the inspection step.

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