Inspection equipment, inspection method, and program

Abstract

In inspections using projection of light and dark patterns, variations in defect detection that may occur depending on the inspection location are suppressed. [Solution] The inspection device 1 comprises a projection unit 2 that projects a light and dark pattern onto the object to be inspected, an imaging unit 3 that captures the object to be inspected on which the light and dark pattern is projected and outputs the captured image, an image processing unit 13 that generates a phase difference image based on a plurality of captured images and generates a corrected phase difference image by applying phase difference correction and geometric correction to the phase difference image, and a detection unit 14 that detects defects occurring in the object to be inspected based on the corrected phase difference image.

Description

Technical Field

[0001] The present disclosure relates to an inspection apparatus, an inspection method, and a program.

Background Art

[0002] There is a technique of projecting a light and dark pattern onto an inspection target (e.g., a painted surface of an automobile), imaging the inspection target onto which the light and dark pattern is projected, and inspecting the inspection target based on the captured image. For example, Patent Document 1 discloses a technique of projecting a light and dark pattern onto an inspection target (inspected surface), imaging it, and inspecting the smoothness of the inspected surface according to the degree of variation in the width of the light and dark boundary region in a binarized image obtained by binarizing the obtained captured image (received light image).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the above-described technique, the inspection target, the imaging unit, and the projection unit are arranged such that the relationship of the regular reflection optical system holds in consideration of the fact that the inspection target has specularity. Therefore, usually, the imaging direction is not perpendicular to the inspection target, and the inspection target is imaged obliquely. Therefore, the imaging distances are different between the front side and the back side of the captured image.

[0005] Also, in the regular reflection optical system, the distances between the positions of the inspection target corresponding to each pixel point of the captured image and the projection unit are different between the front side and the back side of the captured image.

[0006] Due to these reasons, even when the same defect is targeted, there is a possibility that the sensitivity and detection size of defect detection vary depending on the inspection position.

[0007] The purpose of this disclosure is, in view of the above circumstances, to provide an inspection device, etc., that can suppress variations in defect detection that may occur depending on the inspection position in inspection by projection of light and dark patterns. [Means for solving the problem]

[0008] To achieve the above objectives, the inspection apparatus relating to the first aspect of this disclosure is: A projection unit that projects a light and dark pattern onto the object to be inspected, An imaging unit captures the inspection target onto which the aforementioned light and dark pattern is projected and outputs an image; An image processing unit generates a phase difference image based on a plurality of the aforementioned captured images, and generates a corrected phase difference image by applying phase difference correction and geometric correction to the phase difference image, A detection unit that detects defects occurring in the object to be inspected based on the corrected phase difference image, It is equipped with.

[0009] To achieve the above objectives, the inspection method relating to the second aspect of this disclosure is: The light and dark patterns are projected onto the object being examined. The inspection target onto which the aforementioned light and dark pattern is projected is imaged, A phase difference image is generated based on the image of multiple inspection targets obtained by imaging. A corrected phase difference image is generated by applying phase difference correction and geometric correction to the aforementioned phase difference image. Based on the corrected phase difference image, defects occurring in the object to be inspected are detected.

[0010] To achieve the above objectives, the program relating to the third aspect of this disclosure is: On the computer, Project the light and dark pattern onto the object being inspected. The inspection target onto which the aforementioned light and dark pattern is projected is then imaged. A phase-difference image is generated based on the multiple images of the inspection targets obtained by imaging. Phase difference correction and geometric correction are applied to the aforementioned phase difference image to generate a corrected phase difference image. Based on the corrected phase difference image, defects occurring in the inspection target are detected.

Advantages of the Invention

[0011] According to the present disclosure, in inspection by projection of a light and dark pattern, variations related to defect detection that can occur according to the inspection position can be suppressed.

Brief Description of the Drawings

[0012] [Figure 1] It is a diagram showing the overall configuration of an inspection apparatus according to an embodiment of the present disclosure. [Figure 2] It is a diagram showing an example of a light and dark pattern in a projection unit according to an embodiment of the present disclosure. [Figure 3] It is a diagram showing an example of a shift of a light and dark pattern in a projection unit according to an embodiment of the present disclosure. [Figure 4] It is a diagram showing an example of an imaging image obtained by an imaging unit according to an embodiment of the present disclosure. [Figure 5] It is a block diagram showing the functional configuration of a control unit according to an embodiment of the present disclosure. [Figure 6] It is a graph showing an example of a waveform model of a luminance function used in an image processing unit according to an embodiment of the present disclosure. [Figure 7] It is a diagram showing an example of an ideal phase image according to an embodiment of the present disclosure. [Figure 8] It is a diagram showing an example of an ideal phase difference image according to an embodiment of the present disclosure. [Figure 9] It is a diagram for explaining that the range of the irradiation source is different between the front side and the back side in an inspection apparatus according to an embodiment of the present disclosure. [Figure 10] It is a diagram showing an example of the hardware configuration of an image processing apparatus included in an inspection apparatus according to an embodiment of the present disclosure. [Figure 11] It is a flowchart showing an example of an inspection process by an inspection apparatus according to an embodiment of the present disclosure.

Modes for Carrying Out the Invention

[0013] Hereinafter, with reference to the drawings, an inspection apparatus according to an embodiment of the present disclosure will be described. In each of the drawings, the same or equivalent parts are denoted by the same reference numerals.

[0014] (Embodiment) With reference to FIG. 1, an inspection apparatus 1 according to an embodiment will be described. The inspection apparatus 1 detects defects such as dirt and dents occurring in an inspection target K. The inspection apparatus 1 includes a projection unit 2, an imaging unit 3, and a control unit 10. The inspection apparatus 1 projects a light and dark pattern onto the inspection target K by the projection unit 2, images the light and dark pattern projected onto the inspection target K by the imaging unit 3, and processes the captured image obtained by imaging by the control unit 10 to detect defects occurring in the inspection target K. The inspection apparatus 1 is an example of an inspection apparatus according to the present disclosure.

[0015] The inspection target K is assumed to have a smooth surface when no defects occur, such as the painted surface of an automobile.

[0016] As shown in FIG. 2, the projection unit 2 includes a display 20. The projection unit 2 displays a light and dark pattern including light portions 21 and dark portions 22 in the form of slits with a width d arranged alternately on the display 20 based on the control of the control unit 10. The display light L1 emitted from the display 20 that displays the light and dark pattern is irradiated onto the inspection target K, whereby the light and dark pattern is projected onto the inspection target K. The display light L1 is reflected by the inspection target K to become reflected light L2. The light portions 21 are, for example, white slits, and the dark portions 22 are black slits. The projection unit 2 is an example of a projection unit according to the present disclosure.

[0017] The projection unit 2, based on the control of the control unit 10, shifts the brightness pattern displayed on the display 20 by a predetermined amount of time (for example, every 0.1 seconds). For example, in the example shown in Figure 3, the projection unit 2 shifts the brightness pattern by d / 2, which is half the slit width d, at predetermined intervals. From the state shown in Figure 3(A) (initial state), shifting once by a shift width of d / 2 results in the state shown in Figure 3(B), and shifting again results in the state shown in Figure 3(C). Shifting two more times from the state shown in Figure 3(C) results in a total shift of 2d, returning to the state shown in Figure 3(A) (initial state). In other words, by shifting the brightness pattern four times from the initial state, the initial state is returned. In this way, by the projection unit 2 shifting the brightness pattern displayed on the display 20 at predetermined intervals, the brightness pattern projected onto the inspection target K is also shifted at predetermined intervals. When the light / dark pattern is shifted every 0.1 seconds, it takes 0.1 seconds / shift × 4 shifts = 0.4 seconds to return from the initial state to the initial state again. In this case, we can say that one cycle of returning from the initial state to the initial state is 0.4 seconds.

[0018] The imaging unit 3 includes an optical camera and captures an image of the inspection target K onto which a light-dark pattern is projected by receiving reflected light L2. Specifically, based on the control of the control unit 10, the imaging unit 3 captures the light-dark pattern projected onto the inspection target K at the initial state and at each timing when the light-dark pattern is shifted by the projection unit 2. The imaging unit 3 captures the light-dark pattern from the initial state until it returns to the initial state again. For example, if the light-dark pattern is shifted every 0.1 seconds and the shift width is d / 2, the imaging unit 3 captures the light-dark pattern four times in 0.4 seconds. However, it captures once when it is in the initial state and does not capture again when it returns to the initial state. The imaging unit 3 is an example of an imaging means according to this disclosure.

[0019] Since the imaging direction of the imaging unit 3 is oblique to the inspection target K, the part of the object further away from the imaging unit 3 is further away from the imaging unit 3 than the part closer to the imaging unit 3, and is therefore captured smaller than the part closer to the imaging unit 3. As a result, the image obtained by the imaging unit 3 capturing the light and dark pattern projected onto the inspection target K (hereinafter referred to as the "light and dark pattern image") is distorted as shown in Figure 4. In the example shown in Figure 4, the rectangular inspection target is distorted into a trapezoidal shape. In the light and dark pattern image, the part further away is captured smaller than the part closer to the imaging unit, so the effective pixel resolution of the part further away is greater than the effective pixel resolution of the part closer to the imaging unit. In addition, the phase difference, which will be discussed later, tends to be smaller on the far side than on the near side.

[0020] As shown in Figure 5, the control unit 10 has a functional configuration comprising a projection control unit 11, an imaging control unit 12, an image processing unit 13, a detection unit 14, and a notification unit 15.

[0021] The projection control unit 11 controls the projection unit 2 to display a light and dark pattern on the display 20 of the projection unit 2. The projection control unit 11 controls the projection unit 2 to shift the light and dark pattern displayed on the display 20 by a predetermined width at predetermined intervals. When the projection control unit 11 shifts the light and dark pattern, it outputs a signal to the imaging control unit 12 indicating that a shift is to be made.

[0022] When the imaging control unit 12 receives a signal from the projection control unit 11 indicating a shift in the light / dark pattern, it controls the imaging unit 3 to capture the light / dark pattern projected onto the inspection target K. The imaging control unit 12 outputs the light / dark pattern image obtained by the imaging unit 3 capturing the light / dark pattern projected onto the inspection target K to the image processing unit 13. Each time the imaging control unit 12 receives a signal from the projection control unit 11 indicating a shift in the light / dark pattern, it controls the imaging unit 3 to capture the light / dark pattern and outputs the light / dark pattern image to the image processing unit 13. Therefore, the imaging control unit 12 outputs multiple light / dark pattern images that change in accordance with the shift in the light / dark pattern to the image processing unit 13. However, the imaging control unit 12 stops capturing images when the light / dark pattern returns to its initial state.

[0023] The image processing unit 13 performs image processing on multiple brightness-dark pattern images output by the imaging control unit 12, and outputs a single image obtained through image processing (referred to as a "corrected phase difference image," which will be described in detail later) to the detection unit 14. As will be described later, the detection unit 14 detects defects occurring in the inspection target K based on the corrected phase difference image. The image processing unit 13 is an example of an image processing unit according to this disclosure.

[0024] The image processing unit 13 performs four image processing operations described below: phase image generation, phase difference image generation, phase difference correction, and geometric correction.

[0025] The image processing unit 13 generates a single phase image based on multiple brightness / dark pattern images output by the imaging control unit 12, and then generates a phase difference image based on the phase image.

[0026] A phase image is created by focusing on a pixel at a specific location within an image. The brightness values ​​of the pixel at that location are considered as points extracted from a periodic function with period 1, and based on these extracted points, the phase at a specific timing, such as immediately after reaching the maximum value in the periodic function, is determined. The resulting phase value is then converted to a 256-level brightness scale to create the image.

[0027] Here, "phase" refers to the amount of shift from the initial state of the brightness pattern, viewed in units of periods. Furthermore, the periodic function here refers to a method that differs from conventional imaging methods, where the brightness values ​​obtained by focusing on pixels at specific positions from countless brightness pattern images captured by shifting the brightness pattern infinitely finely by one period correspond to the phase at the time each brightness pattern image was captured, with the phase at the time of capture as an argument.

[0028] In this specification, unless otherwise specified, the phase at a particular timing is assumed to be the phase immediately after the maximum value is reached in a periodic function. Furthermore, the phase value at a particular timing will be referred to as the phase value below.

[0029] For example, in the example shown in Figure 3, among the multiple light and dark pattern images, the phase value at the pixel position that can be considered to be immediately after reaching the maximum in the periodic function when imaged in the initial state, Figure 3(A), is 0, and the pixel value of the phase image at that position is also 0. Similarly, in the states of Figure 3(B) and (C), the phase values ​​at the pixel positions that can be considered to be immediately after reaching the maximum in the periodic function are 1 / 4 and 1 / 2, respectively, and the pixel values ​​of the phase image at those positions are (Q+1) / 4 and (Q+1) / 2, respectively, where Q is the maximum possible pixel value of the phase image. For example, when each pixel of the phase image is represented by a 7-bit value (128 gradations), Q is 127. As will be described in detail later, when each pixel of the phase difference image is represented by an n-bit value (n is an integer of 2 or more), it is preferable that each pixel value of the phase image be represented by an n-1-bit value.

[0030] When the shift width of the brightness pattern is sufficiently fine, the phase value can be accurately determined by directly identifying how much the image captured immediately after the brightness reached its maximum was phase-shifted from the initial state for each pixel position. However, from a practical standpoint, making the shift width too fine can increase the imaging time and data volume, which can be problematic. On the other hand, when the shift width is not fine, such as two-fifths of the slit width, simply checking the brightness values ​​of the captured image may not accurately determine the phase value. Therefore, the following method of determining the phase value can also be considered.

[0031] Let p(x,y,θ) be the brightness value of the pixel at position (x,y) captured when phase θ is given. For example, in the state shown in Figure 3(A), θ=0, and in the state shown in Figure 3(B), θ=1 / 4. The objective of creating a phase image is to find θ=θm for each position (x,y) immediately after the periodic function reaches its maximum. Furthermore, the obtained phase value θm is normalized to a value between 0 and 1 to make it suitable for imaging. p(x,y,θ) is expressed by the following equation using the phase value θm to be found, a periodic function F with phase as an argument (hereinafter referred to as the "brightness function F"), and an initial phase φ(x,y) that depends on the position (x,y). p(x,y,θm)=F(θm+φ(x,y))

[0032] When the brightness value of p(x,y,θ) is graphed with respect to position (x,y) and phase θ as a variable, it can be approximated by a rectangular wave waveform model with a slope-like rise and fall, as shown in Figure 6.

[0033] Therefore, by adopting a luminance function F that approximates this waveform model, with parameters such as the phase and maximum bandwidth at a specific timing, and by identifying the luminance values ​​for each of the multiple brightness / dark pattern images at several pixel positions, the phase value can be determined with high accuracy.

[0034] The following is an example of a specific method for determining the phase value. In the waveform model shown in Figure 6, the rising and falling regions can be expressed as linear functions with phase as an argument, using the maximum and minimum values ​​of the luminance function F, as well as the maximum bandwidth and phase value. Here, the maximum and minimum values ​​are assumed to be obtained from the luminance values ​​of multiple light and dark pattern images, while the maximum bandwidth and phase value are treated as unknowns. Also, taking into account that the widths of the light and dark parts of the light and dark pattern are the same, the minimum bandwidth and maximum bandwidth, as well as the rising and falling region bandwidths, are treated as having the same width. By substituting the luminance values ​​obtained in the rising and falling regions and their corresponding phases into the two linear functions for the rising and falling regions, a system of equations with the maximum bandwidth and phase value as unknowns is obtained, and the desired phase value can be obtained by solving this system of equations.

[0035] The phase image generated by determining the phase value in this way is ideally a gradient, as shown in Figure 7, except for the defective area D. In the phase image shown in Figure 7, the darker the pixel, the smaller the pixel value and therefore the smaller the phase value, and the whiter the pixel, the larger the pixel value and therefore the larger the phase value. The boundaries of each gradient are the parts before and after the phase value returns to 0, for example, the part where the pixel value returns from the maximum value of 127 to 0. As shown in Figure 3, when the light and dark pattern continues to shift to the right, in the normal area, the phase value increases monotonically from left to right, so the pixel value is larger on the right side than on the left side. On the other hand, in the defective area D, the phase value is different from that of the normal area due to dirt, depressions, etc., so the pixel distribution in the phase image is different from that of the normal area.

[0036] However, in reality, as mentioned above, the light-dark pattern image becomes distorted as shown in Figure 4, and therefore the phase image and the phase difference image generated based on it also become distorted.

[0037] Next, we will explain phase difference images. A phase difference image is an image in which the pixel value of each pixel is the difference between the pixel value of the phase image at the pixel's position and the pixel value of the pixel adjacent to it in the shift direction. For example, in the example shown in Figure 7, the pixel value at each position is the value obtained by subtracting the pixel value at that position from the pixel value of the pixel to the right (in the shift direction) of that position. However, near the boundaries of each gradient shown in Figure 7, and near the defective area D, this subtracted value may be negative. Since the pixel values ​​of image data are generally non-negative integers, it is preferable to add an appropriate value (offset value) to make the pixel value a non-negative integer. For example, when the range of possible pixel values ​​for the phase image is 0 to 127 (128 gradations) as a 7-bit non-negative integer, the range of possible values ​​for this subtracted value is -127 to 127. Therefore, by adding 127 or 128 as an offset value to this subtracted value, the pixel values ​​of the phase difference image can be made into 8-bit non-negative integers.

[0038] As shown in Figure 7, the phase image changes smoothly in the normal portion, except for the parts before and after the phase value returns to 0 (the gradation boundaries). Therefore, the phase difference is generally constant except for the parts before and after the phase value returns to 0. On the other hand, the parts before and after the phase value returns to 0 have a phase difference of almost one full cycle (however, it is a negative value) because the phase value has completed a full cycle and returned to 0, and if we assume that it does not return to 0 after a full cycle, it will change smoothly. As will be discussed later, defect detection utilizes the fact that the phase difference is generally constant in the normal state, so it is preferable to treat these parts similarly. Therefore, in areas with extremely large phase differences, the value of one full phase cycle can be added to treat them the same as other parts.

[0039] In this way, by correcting the phase difference value as needed, ideally, for example, the phase difference image shown in Figure 8 can be generated from the phase image shown in Figure 7. However, in Figure 8, pixels showing a phase difference that is expected to be constant in the normal portion are shown in white. As shown in Figure 8, the pixels (phase difference) at each point of the defective portion D will be different from those in the normal portion. The detection unit 14, described later, uses this to perform defect detection.

[0040] However, in reality, as mentioned above, phase-contrast images are distorted, just like light-dark pattern images. Therefore, if the same defect is detected on both the far side (farther from the imaging unit 3) and the near side (closer to the imaging unit 3) of the image, there will be a difference in the detected size. Furthermore, as explained below, due to the difference in the distance between the inspection target point and the projection unit, the phase difference tends to be smaller on the far side of the phase-contrast image than on the near side. In other words, the defect detection sensitivity changes when phase difference is used as the criterion for defect detection. This means that even if the apparent size of the same defect is corrected by geometric calculations, it may not be possible to detect it in the same way on both the near and far sides of the image.

[0041] To mitigate these differences in defect detection, the defect detection sensitivity and defect detection size are corrected using phase difference correction and geometric correction, respectively, as described later.

[0042] As shown in Figure 9, consider a front portion B1 and a back portion B2 on the object K to be inspected, which have the same shape but are located in different positions. Both the front portion B1 and the back portion B2 reflect the display light L1 from the projection unit 2, and the reflected light L2 is received by the imaging unit 3. The dashed line in Figure 9 represents the light related to the front portion B1, and the dashed line represents the light related to the back portion B2. As shown in Figure 9, the front portion B1 is farther from the projection unit than the back portion B2, so it can be illuminated from a wider area on the projection unit 2. Therefore, even though they have the same shape, the front portion B1 can contribute to a wider range of light and dark patterns than the back portion B2, and the amount of phase value change in the back portion B2 area is smaller than in the front portion B1 area. Therefore, it is necessary to correct this difference in phase difference by phase difference correction, which will be described later.

[0043] The image processing unit 13 applies phase difference correction to the phase difference image to correct the difference in phase between the foreground and background portions. For example, it is conceivable to correct each pixel by multiplying its phase difference by a predetermined coefficient. The coefficient here is determined for each pixel based on the distance from the corresponding inspection target position to the corresponding projection position when viewed through a specular reflection optical system.

[0044] By multiplying the phase difference by such a coefficient, it is possible to correct for the smaller phase difference on the far side compared to the near side.

[0045] The reasoning behind determining the coefficients is as follows: When the distance from the inspection target position to the projection area corresponding position is long, the angle change at the inspection target is large when viewed as a change at the projection area corresponding position, and when it is short, it is small. Considering that the brightness / darkness pattern pitch is constant, large and small changes at the projection area corresponding to large and small phase changes, respectively, result in differences in the appearance of defects on the phase difference image. In other words, the degree of defect appearance strongly depends on the distance from the inspection target position to the projection area corresponding position, so the coefficients were determined based on this distance. In addition, in some cases, differences in effective pixel resolution due to differences in the distance between each point on the inspection target and the camera may affect the rate of tilt change between neighboring pixels, so such factors may also be appropriately taken into account when determining the coefficients as needed.

[0046] The image processing unit 13 performs geometric correction on the phase difference image that has undergone phase difference correction. For example, if a rectangular planar inspection object is deformed into a trapezoid shape on the phase difference image, it is corrected to a rectangular shape that reflects the original shape. Hereinafter, this type of correction is referred to as geometric correction. Geometric correction refers to correcting an inspection object that is distorted on an image to a shape that reflects the original shape, using geometric image processing such as trapezoidal correction or perspective projection correction. For example, as shown in Figure 4, if a rectangular planar inspection object is distorted into a trapezoid shape on a light-dark pattern image, the phase difference image will also be distorted into a trapezoid shape, and can be corrected into a rectangular shape by trapezoidal correction. On the other hand, depending on how the camera is mounted, a rectangular planar inspection object may be distorted in a way that is different from a trapezoid on a light-dark pattern image, and it may be difficult to correct it into a rectangular shape with trapezoidal correction. In such cases, the distorted phase difference image can be corrected into a rectangular shape by perspective projection correction.

[0047] The image obtained by applying phase difference correction and geometric correction to the phase difference image will be referred to below as the "corrected phase difference image". The image processing unit 13 outputs the obtained corrected phase difference image to the detection unit 14.

[0048] In summary, the image processing unit 13 generates a phase image based on each of the multiple brightness pattern images captured in accordance with the shift of the brightness pattern, generates a phase difference image based on the phase image, and generates a corrected phase difference image by applying phase difference correction and geometric correction to the phase difference image, and outputs it to the detection unit 14.

[0049] The detection unit 14 detects defects occurring in the inspection target K based on the corrected phase difference image output by the image processing unit 13. More specifically, the detection unit 14 scans each pixel of the corrected phase difference image and detects areas where the pixel value (phase difference) changes rapidly as defective areas. If this detection process were performed on the uncorrected phase difference image instead of the corrected phase difference image, differences in resolution between the foreground and background due to the shooting distance, and differences in phase difference between the foreground and background, would result in differences in defect detection sensitivity and detection size between the foreground and background. In other words, variations in defect detection sensitivity and detection size would occur depending on the inspection position. Therefore, the above correction can suppress variations in defect detection. When the detection unit 14 detects a defect, the notification unit 15 notifies that a defect has been detected, the location of the defect, etc. The detection unit 14 is an example of a detection unit according to this disclosure.

[0050] The notification unit 15 notifies the user of the defect detected by the detection unit 14. The notification unit 15 includes, for example, a display, which notifies the user that a defect exists and the location where the defect is occurring.

[0051] Next, an example of the hardware configuration of the control unit 10 will be described with reference to Figure 10. The control unit 10 shown in Figure 10 is implemented by a computer such as a personal computer or a microcontroller.

[0052] The control unit 10 comprises a processor 1001, a memory 1002, an interface 1003, and a secondary storage device 1004, all of which are connected to each other via a bus 1000.

[0053] The processor 1001 is, for example, a CPU (Central Processing Unit). The processor 1001 reads the operation program stored in the secondary storage device 1004 into the memory 1002 and executes it, thereby realizing each function of the control unit 10.

[0054] Memory 1002 is a main memory device, for example, composed of RAM (Random Access Memory). Memory 1002 stores the operational program read by the processor 1001 from the secondary memory device 1004. Memory 1002 also functions as working memory when the processor 1001 executes the operational program.

[0055] Interface 1003 is an I / O (Input / Output) interface such as a serial port, USB (Universal Serial Bus) port, or network interface. The projection unit 2, imaging unit 3, etc., are connected to interface 1003.

[0056] The secondary storage device 1004 is, for example, flash memory, an HDD (Hard Disk Drive), or an SSD (Solid State Drive). The secondary storage device 1004 stores the operational programs that the processor 1001 executes.

[0057] An example of the inspection process performed by the inspection device 1 will be explained with reference to Figure 11. The inspection process shown in Figure 11 is started, for example, when a user operates the inspection device 1 and instructs it to start the inspection.

[0058] The projection control unit 11 of the control unit 10 of the inspection device 1 controls the projection unit 2 to start projecting the light and dark pattern onto the inspection target K (step S1).

[0059] The imaging control unit 12 of the control unit 10 controls the imaging unit 3 to capture the light and dark pattern projected onto the inspection target K, and waits for a predetermined period (step S2). Through this predetermined waiting period and the repetition from step S3 described later, the light and dark pattern is shifted at predetermined intervals, and the light and dark pattern is captured in accordance with the shift. The imaging control unit 12 outputs the captured light and dark pattern image to the image processing unit 13.

[0060] The projection control unit 11 controls the projection unit 2 to shift the brightness pattern by a predetermined width (step S3).

[0061] The control unit 10 determines whether the number of times the light-dark pattern has been captured since the start of the inspection process has reached a predetermined number (step S4). If the number of captures has not reached the predetermined number (step S4: No), the control unit 10 repeats the operation from step S2. If the number of captures has reached the predetermined number (step S4: Yes), the control unit 10 executes the operation from step S5 onward. As a result, the light-dark pattern is shifted a predetermined number of times at predetermined intervals, and the light-dark pattern is captured with each shift.

[0062] The image processing unit 13 of the control unit 10 generates a phase image based on the brightness-dark pattern image output a predetermined number of times from the imaging control unit 12, and generates a phase difference image based on the generated phase image (step S5).

[0063] The image processing unit 13 applies phase difference correction and geometric correction to the phase difference image generated in step S5 to generate a corrected phase difference image, and outputs the generated corrected phase difference image to the detection unit 14 (step S6).

[0064] The detection unit 14 detects defects occurring in the inspection target K based on the corrected phase difference image output by the image processing unit 13 (step S7).

[0065] When it is determined that a defect has been detected (Step S8: Yes), the detection unit 14 controls the notification unit 15 to notify the user of the defect (Step S9). The inspection device 1 then terminates the inspection process. When it is determined that no defect has been detected (Step S8: No), the inspection device 1 terminates the inspection process without executing the process in Step S9.

[0066] The inspection apparatus 1 according to the embodiment has been described above. According to the inspection apparatus 1, after capturing multiple images of the light and dark pattern projected onto the object to be inspected K, a phase image and a phase difference image are generated based on the light and dark pattern images obtained by the capture, and then a defect detection is attempted after applying phase difference correction and geometric correction to the phase difference image. Since the difference between the front and back sides can be corrected by the phase difference correction and geometric correction, variations in defect detection that may occur depending on the inspection position can be suppressed.

[0067] (modified version) In the embodiment, a light-dark pattern image was captured at predetermined intervals. In other words, the light-dark pattern image was captured at regular intervals. However, if the amount of shift is known, the multiple light-dark pattern images used in generating the phase image do not need to be captured at regular intervals. This is because, when generating the phase image, it is sufficient to know how much each light-dark pattern image has shifted from its initial state.

[0068] In the hardware configuration shown in Figure 10, the control unit 10 is equipped with a secondary storage device 1004. However, the configuration is not limited to this; the secondary storage device 1004 may be located outside the control unit 10, and the control unit 10 and the secondary storage device 1004 may be connected via an interface 1003. In this configuration, removable media such as USB flash drives and memory cards can also be used as the secondary storage device 1004.

[0069] Alternatively, instead of the hardware configuration shown in Figure 10, the control unit 10 may be configured using a dedicated circuit such as an ASIC (Application Specific Integrated Circuit) or FPGA (Field Programmable Gate Array). Furthermore, in the hardware configuration shown in Figure 10, some of the functions of the control unit 10 may be implemented by a dedicated circuit connected to interface 1003, for example. [Explanation of Symbols]

[0070] 1. Inspection device 2 Projection section 3. Imaging Unit 10 Control Unit 11 Projection Control Unit 12 Imaging control unit 13 Image Processing Unit 14 Detection unit 15 Hochi Department 20 displays 21 Akabe 22 Dark part 1000 bus 1001 Processor 1002 memory 1003 Interface 1004 Secondary storage device B1 Front section B2 Back part D. Defective part L1 display light L2 reflected light K Test Subject

Claims

1. A projection unit that projects a light and dark pattern onto the object to be inspected, An imaging unit captures the inspection target onto which the aforementioned light and dark pattern is projected and outputs an image; An image processing unit generates a phase difference image based on a plurality of the aforementioned captured images, and generates a corrected phase difference image by applying phase difference correction and geometric correction to the phase difference image, A detection unit that detects defects occurring in the object to be inspected based on the corrected phase difference image, An inspection device equipped with the following features.

2. The projection unit projects the light and dark pattern while shifting it at predetermined intervals. The imaging unit captures an image of the object to be inspected for each shift, The image processing unit generates the corrected phase difference image based on the plurality of captured images obtained by capturing for each shift. The inspection apparatus according to claim 1.

3. The light and dark patterns are projected onto the object being examined. The inspection target onto which the aforementioned light and dark pattern is projected is imaged, A phase difference image is generated based on the image of multiple inspection targets obtained by imaging. A corrected phase difference image is generated by applying phase difference correction and geometric correction to the aforementioned phase difference image. Based on the corrected phase difference image, defects occurring in the object to be inspected are detected. Testing method.

4. On the computer, Project the light and dark pattern onto the object being inspected. The inspection target onto which the aforementioned light and dark pattern is projected is then imaged. A phase-difference image is generated based on the multiple images of the inspection targets obtained by imaging. Phase difference correction and geometric correction are applied to the aforementioned phase difference image to generate a corrected phase difference image. Based on the corrected phase difference image, defects occurring in the object to be inspected are detected. program.

Images