JP7415215B1 - Visual inspection equipment - Google Patents

Abstract

An object of the present invention is to provide an appearance inspection device that can obtain a high-resolution image of a side surface of a workpiece while suppressing damage to the workpiece. An appearance inspection apparatus 1 of the present invention includes imaging devices 31 and 32 that capture images of side surfaces Ws1 and Ws2 of a workpiece W at a plurality of different positions to obtain a plurality of captured images P, and a first A first feature detection process that detects the feature part Wc1, a first focus degree evaluation process that evaluates the degree of focus of the first feature part Wc1, and a first feature evaluation process that evaluates the degree of focus of the first feature part Wc1 in a plurality of captured images P. A first reference image selection process in which one of the plurality of captured images P is selected as the first reference image Ps1 by comparing, and a characteristic region Rc that is an area including the first characteristic portion Wc1 in the first reference image Ps1. , an evaluation process for evaluating the workpiece W based on the region to be inspected Ri, which is a region corresponding to the characteristic region Rc in the captured image P other than the first reference image Ps1. [Selection diagram] Figure 8

Description

The present invention relates to an appearance inspection device that images the appearance of an object to be inspected (work).

An external appearance inspection is performed in which an image of the external appearance of a workpiece is captured using an imaging device such as a camera, and the acquired image is used to check whether there is any abnormality in the shape of the workpiece, adhesion of foreign matter, or the like. When performing this kind of visual inspection on the side of a workpiece, the workpiece is usually transported so that the side of the workpiece faces the imaging device, and the side of the workpiece is imaged, or a lens with a deep depth of field is used. The side of the workpiece may be imaged from an oblique direction.

Japanese Patent Application Publication No. 2007-303853

However, in the method of transporting the workpiece and photographing its side surface, there is a risk that scratches or foreign matter may adhere to the workpiece during transport and damage the workpiece. Furthermore, in the method of using a lens with a deep depth of field, since the numerical aperture of the lens is small, there is a possibility that a high-resolution image cannot be obtained.

The present invention has been made in view of the above-mentioned points, and an object of the present invention is to provide an appearance inspection device that can obtain a high-resolution image of the side surface of a workpiece while suppressing damage to the workpiece.

The present invention includes the embodiments shown below.

[1] An imaging device that captures a side surface of a workpiece to generate a captured image, a movement mechanism that moves the imaging device along the side surface of the workpiece, and an image processing unit that performs image processing on the captured image; An appearance inspection apparatus comprising: the imaging device capturing images of a side surface of the workpiece at a plurality of different positions moved by the moving mechanism to obtain a plurality of captured images; and the image processing unit: a first feature detection process that detects a first feature from the captured image; a first focus evaluation process that evaluates the degree of focus of the first feature; and the first feature in the plurality of captured images. a first reference image selection process of selecting one of the plurality of captured images as a first reference image by comparing the degree of focus of the first reference image; and a region including the first characteristic part in the first reference image. a characteristic region; and an area in the captured image other than the first reference image that corresponds to the characteristic region and is provided at a position corresponding to the position occupied by the characteristic region in the first reference image. An appearance inspection device that performs an evaluation process of evaluating the workpiece based on an area to be inspected.

[2] In the first reference image selection process, the image processing unit selects the first reference image by comparing the degrees of focus of the first characteristic portions of some of the plurality of captured images. The external appearance inspection device according to [1] above.

[3] The image processing unit according to [1] or [2] above executes a compositing process that connects the characteristic region and the inspected region to generate a composite image representing a side surface of the workpiece. Appearance inspection equipment.

[4] A plurality of the imaging devices are provided, and the plurality of imaging devices are moved together by the moving mechanism along the side surface, and synchronously image the side surface to obtain a plurality of captured images, respectively. The visual inspection device according to any one of [1] to [3] above.

[5] The image processing unit performs a second feature detection process that detects a second feature that is different from the first feature from the captured image, and a second focus that evaluates the degree of focus of the second feature. a second reference image selection process of selecting one of the plurality of captured images as a second reference image by comparing the degree of focus of the second characteristic portion in the plurality of captured images; [1] above, wherein a correction process is executed to correct the inspection area based on the position of the first characteristic part in the first reference image and the position of the two characteristic parts in the second reference image. [4] The visual inspection device according to any one of the above.

According to the present invention, it is possible to obtain a high-resolution image of the side surface of a workpiece while suppressing damage to the workpiece.

A diagram showing a schematic configuration of an appearance inspection device according to an embodiment of the present invention Block diagram showing the configuration of the visual inspection device A diagram illustrating an image captured by the side imaging device of the appearance inspection device. Diagram illustrating how the region setting unit sets feature regions Diagram explaining how the area setting unit sets the inspection area A diagram illustrating the characteristic region and the inspected region set by the region setting unit Diagram showing an example of a composite image created by a visual inspection device Flowchart showing the inspection process of the visual inspection device A block diagram showing the configuration of a visual inspection device according to modification example 1 of the present invention. A diagram illustrating a method for the correction unit to specify the position of the first characteristic portion in Modification Example 1 of the present invention A diagram illustrating a method for the correction unit to specify the position of the second characteristic portion in Modification Example 1 of the present invention A diagram illustrating a method by which the correction unit corrects the inspection area Ri in Modification Example 1 of the present invention

Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

(1) Configuration of visual inspection device 1 First, the configuration of visual inspection device 1 of this embodiment will be described based on FIGS. 1 and 2. As shown in FIGS. 1 and 2, the appearance inspection apparatus 1 includes a stage 2, an imaging section 3, a moving mechanism 4, and a control device 5, and includes a side surface Ws1 of a workpiece W placed on the stage 2, This is a device that images and inspects Ws2.

In the following explanation, the direction in which the side surfaces Ws1 and Ws2 face each other (the direction indicated by the arrow X in FIG. 1) is referred to as the left-right direction X, the direction perpendicular to the paper surface of FIG. 1 is referred to as the front-back direction Y, and The direction indicated by Z is the up-down direction. Also, in the captured images of the side surfaces Ws1 and Ws2 of the workpiece W captured by the imaging unit 3, the longitudinal direction of the side surfaces Ws1 and Ws2, which corresponds to the front-rear direction Y when placed on the stage 2, is indicated by an arrow Y. The vertical direction is indicated by an arrow Z.

On the stage 2, a workpiece W to be inspected is placed. Note that the workpiece W placed on the stage 2 has side surfaces Ws1 and Ws2 obliquely facing side imaging devices 31 and 32, which will be described later.

The imaging unit 3 includes side imaging devices 31 and 32 that include a CCD (Charge Coupled Device) camera or a CMOS (Complementary Metal Oxide Semiconductor) camera to which an objective lens is attached. The side imaging devices 31 and 32 photograph side surfaces Ws1 and Ws2 of the workpiece W placed on the stage 2 from diagonally above.

More specifically, the side imaging device 31 is arranged such that the optical axis L1 is inclined obliquely upward by an angle θ with respect to the normal direction H1 of one side surface Ws1 of the workpiece W, and It is set so that only a part of the vertical direction Z is included in the imaging range (field of view), and the entire front-back direction Y of the side surface Ws1 of the workpiece W is included in the imaging range.

The side imaging device 32 is configured from a device having the same structure and arranged laterally symmetrically with the side imaging device 31. That is, the side imaging device 32 is arranged such that the optical axis L2 is inclined obliquely upward by an angle θ with respect to the normal direction H2 of the side surface Ws2 of the workpiece W, and only a portion of the side surface Ws2 of the workpiece W in the vertical direction Z is disposed. is included in the imaging range, and the entire side surface Ws2 of the workpiece W in the front-rear direction Y is set to fall within the imaging range.

The side imaging devices 31 and 32 capture images of the workpiece W and output the generated captured images to the control device 5. Note that the imaging unit 3 and the control device 5 may be connected wirelessly or by wire.

The moving mechanism 4 includes a holding base 41 to which the side imaging devices 31 and 32 are fixed, a guide rail 42 that holds the holding base 41 slidably in the vertical direction, and a holding base 41 that moves the holding base 41 up and down along the guide rail 42. and a drive unit (not shown) that causes the drive unit to move. The moving mechanism 4 moves the side imaging devices 31 and 32 together only in the vertical direction while restricting movement in the left-right, front-back, and front-back directions.

The control device 5 includes a processing device 51 such as a computer, and a storage device 52 such as a memory, and when the processing device 51 reads and executes a program stored in the storage device 52, the device control unit 53, a data acquisition section 54, and an image processing section 60.

The device control unit 53 controls the side image pickup devices 31 and 32 and the moving mechanism 4 to move the side image pickup devices 31 and 32 in the vertical direction Z, while using the side image pickup devices 31 and 32 to capture the side surfaces Ws1 and 1 of the workpiece W. Ws2 is imaged in synchronization.

Specifically, the device control unit 53 controls the moving mechanism 4 so that the side imaging devices 31 and 32 move in the vertical direction Z along the side surfaces Ws1 and Ws2 of the workpiece W from the imaging start position to the imaging end position. do. The imaging start position is set to a position where the upper end E1 of the side surfaces Ws1, Ws2 of the workpiece W is included in the imaging range of the side imaging devices 31, 32. The imaging end position is set to a position where the lower ends E2 of the side surfaces Ws1 and Ws2 of the workpiece W are included in the imaging range of the side imaging devices 31 and 32.

In addition, while the side imaging devices 31 and 32 are moved by the moving mechanism 4 from the imaging start position to the imaging end position, the device control unit 53 causes the side imaging devices 31 and 32 to move a predetermined distance in the vertical direction Z (hereinafter referred to as this distance). is sometimes referred to as an "imaging pitch"), a portion of the side surfaces Ws1 and Ws2 of the workpiece W in the vertical direction Z is imaged every time the workpiece W moves by D.

Here, the imaging pitch D is set to satisfy the following equation (1), and preferably, to satisfy the equation (2).

式（１）及び式（２）において、Ａは側面撮像装置３１，３２に設けられた対物レンズ等のレンズの被写界深度、θはワークＷの側面Ｗｓ１，Ｗｓ２の法線方向Ｈ１，Ｈ２に対する側面撮像装置３１、３２の光軸Ｌ１，Ｌ２の角度θである。つまり、撮像ピッチＤは、レンズの被写界深度に入る上下方向の最大長さ（Ａ／ｓｉｎθ）以下に設定され、上記の最大長さの半分以下に設定されることが好ましい。

In formulas (1) and (2), A is the depth of field of lenses such as objective lenses provided in the side imaging devices 31 and 32, and θ is the normal direction H1 and H2 of the side surfaces Ws1 and Ws2 of the workpiece W. This is the angle θ of the optical axes L1 and L2 of the side imaging devices 31 and 32 with respect to the angle θ. In other words, the imaging pitch D is set to be less than or equal to the maximum vertical length (A/sin θ) within the depth of field of the lens, and is preferably set to less than half of the above-mentioned maximum length.

As shown in FIG. 3, the side imaging devices 31 and 32 change the side surface Ws1 of the work W captured at the imaging end position from the captured image P1 in which the upper end E1 of the work Ws1 and Ws2 of the work W captured at the imaging start position are captured. , Ws2, up to the captured image Pn in which the lower end E2 of Ws2 is captured, data is generated for a plurality of n captured images P whose imaging ranges differ by the imaging pitch D in the vertical direction Z (n is an integer of 2 or more).

The obtained plurality of captured images P are images taken with the optical axes L1, L2 of the side image capturing devices 31, 32 tilted with respect to the side surfaces Ws1, Ws2 of the workpiece W, so that a portion of the captured images P in the vertical direction Z is The image is in focus.

In the following description, the image captured at the imaging start position is referred to as the first captured image P1, and the m-th image captured after imaging at the imaging start position is referred to as the m-th captured image Pm. The image captured at the end position is referred to as the nth captured image Pn, and the 1st to nth captured images P1 to Pn are collectively referred to as the captured image P.

The data acquisition unit 54 acquires data of a plurality of n captured images P generated by the side imaging devices 31 and 32, respectively. The data acquisition unit 54 associates the data of the acquired captured image P with the number of the captured image P (that is, the ordinal number of the captured image P). The data linked in the data acquisition unit 54 is stored in the storage device 52.

The image processing unit 60 sets a characteristic region Rs and a region to be inspected Rm in the plurality of n captured images P stored in the storage device 52, and determines the side surface of the workpiece W based on the set characteristic region Rs and the region to be inspected Rm. Evaluate Ws1 and Ws2.

(2) Image processing section 60
As shown in FIG. 2, the image processing section 60 includes a first feature detection section 61, a first focus degree evaluation section 62, a first reference image selection section 63, an area setting section 64, a composition section 65, and an evaluation section 66. have.

Note that since the image processing unit 60 executes the same process for the captured image P captured by the side imaging device 31 and the captured image P captured by the side imaging device 32, here, only one side imaging device 31 is executed. The processing for the captured image P captured by the other side imaging device 32 will be described, and the detailed description of the processing for the captured image captured by the other side imaging device 32 will be omitted.

The first feature detection unit 61 detects the first feature Wc1 from the captured image P stored in the storage device 52. In this embodiment, the first feature detection unit 61 detects the upper end E1 of the side surface Ws1 of the workpiece W as the first feature Wc1.

Further, as the first characteristic portion Wc1 detected by the first characteristic detection unit 61, an edge portion of the workpiece W such as the upper end E1 of the side surface Ws1 of the workpiece W can be mentioned. In addition to the edge portion of the workpiece W, if there is a pattern or mark provided on the side surface Ws1 of the workpiece W that allows the first focus evaluation unit 62 to evaluate the focus degree, the workpiece W may be Any location on the side surface Ws1 can be the first feature Wc1.

The first focus evaluation section 62 evaluates the focus degree of the first feature portion Wc1 detected by the first feature detection section 61. Various methods can be adopted as a method for evaluating the degree of focus of the first feature Wc1. For example, for each captured image P in which the first feature detection unit 61 detects the first feature Wc1, The sharpness value of the portion Wc1 is calculated, and a captured image with a larger sharpness value is evaluated as an image with a higher degree of focus.

The first reference image selection unit 63 selects one image with the highest degree of focus from the captured images evaluated by the first focus degree evaluation unit 62 as the first reference image Ps1. Further, the first reference image selection unit 63 sets the captured image P obtained by removing the first reference image Ps1 from the plurality of n captured images P stored in the storage device 52 as the inspection image Pt.

For example, if the captured image with the highest degree of focus among the n captured images P evaluated by the first focus degree evaluation unit 62 is the second captured image P2, the first reference image selection unit 63 The image P2 is selected as the first reference image Ps1, and the other captured images P1, P3, P4...Pn-1, Pn are set as the inspection images Pt (see FIG. 3).

The region setting unit 64 sets a region Rc including the first characteristic portion Wc1 from the first reference image Ps1. Further, the area setting unit 64 sets an area corresponding to the characteristic area Rc set in the first reference image Ps in the inspection image Pt as the area to be inspected Ri.

Specifically, as shown in FIG. 4, the area setting unit 64 moves a predetermined number of pixels Δe from the first characteristic portion Wc1 of the first reference image Ps1 in the moving direction of the side imaging device 31 (that is, in the vertical direction Z). Assuming that the distant points are boundaries B1 and B2, the area sandwiched between these boundaries B1 and B2 is set as the characteristic area Rc. Note that the boundaries B1 and B2 are set so that the vertical width F (number of pixels) of the feature region Rc satisfies the following formula (3), and preferably the boundaries B1 and B2 are set so that the width F satisfies formula (4). B2 is set.

式（３）及び式（４）において、Ａは側面撮像装置３１，３２に設けられた対物レンズ等のレンズの被写界深度、Ｍはレンズの倍率、Ｓｐは側面撮像装置３１，３２に搭載されているイメージセンサの１ピクセルの大きさ、θはワークＷの側面Ｗｓ１，Ｗｓ２の法線方向Ｈ１，Ｈ２に対する側面撮像装置３１、３２の光軸Ｌ１，Ｌ２の角度θである。

In equations (3) and (4), A is the depth of field of a lens such as an objective lens provided in the side imaging devices 31, 32, M is the magnification of the lens, and Sp is the depth of field installed in the side imaging devices 31, 32. The size of one pixel of the image sensor θ is the angle θ of the optical axes L1 and L2 of the side imaging devices 31 and 32 with respect to the normal directions H1 and H2 of the side surfaces Ws1 and Ws2 of the workpiece W.

After setting the characteristic region Rc in the first reference image Ps1, the region setting unit 64 specifies the position of the characteristic region Rc in the first reference image Ps1. For example, the region setting unit 64 sets the characteristic region Rc in the first reference image Ps1 by specifying the number of pixels Np1 and Np2 in the vertical direction from the upper end of the first reference image Ps1 to the boundaries B1 and B2. Specify the position (pixel)

Then, as shown in FIG. 5, the area setting unit 64 sets boundaries Bt1 and Bt2 at a position downwardly away from the upper end of the inspection image Pt by the number of pixels Np1 and a position away from the number Np2 by the number of pixels, respectively, and sets boundaries Bt1, The region sandwiched by Bt2 is set as the region to be inspected Ri. The region setting unit 64 performs such setting of the region to be inspected Ri for all inspection images Pt (see FIG. 6).

As shown in FIG. 6, the synthesis unit 65 extracts image data (pixel values) existing in the characteristic region Rc in the first reference image Ps1, and extracts image data (pixel values) existing in the inspected region Ri in the inspection image Pt. Extract image data (pixel values). Note that in order to make it easier to understand the regions extracted from the first reference image Ps1 and the inspection image Pt, the regions are hatched in FIG.

Thereby, image data p extracted from the first reference image Ps1 or the inspection image Pt is generated for all the captured images P from the first to the nth.

Assuming that the image data extracted from the first captured image P1 is the first extracted image data p1, and the image data extracted from the n-th captured image Pn is the n-th extracted image data pn, the combining unit 65 performs the following process as shown in FIG. As shown, a composite image CP of the side surface Ws1 of the workpiece W is created by connecting the extracted image data p from the first extracted image data p1 to the nth extracted image data pn in order from the top.

Then, the evaluation section 66 performs an external appearance inspection of the side surface Ws1 of the workpiece W based on the composite image CP generated by the composition section 65.

(3) Appearance inspection method of the present embodiment A method of inspecting the appearance of the side surfaces Ws1 and Ws2 of the workpiece W using the above-mentioned appearance inspection apparatus 1 will be described with reference to FIG. 8.

First, a workpiece W to be visually inspected is placed on the stage 2 of the visual inspection apparatus 1 (step S1).

Then, while the moving mechanism 4 moves the side imaging devices 31, 32 downward from the imaging start position to the imaging end position along the side surfaces Ws1, Ws2 of the work W placed on the stage 2, the side imaging devices 31, 32 The side surfaces Ws1 and Ws2 of the workpiece W are imaged every time the side surface Ws1 and Ws2 move by the imaging pitch D. Thereby, a plurality of n captured images P are acquired for each of the side surface Ws1 and the side surface Ws2 (step S2).

Then, in the image processing unit 60, the first feature detecting unit 61 detects the first feature portion Wc1 from the plurality of captured images P capturing the side surface Ws1 of the workpiece W. Furthermore, the first characteristic portion Wc1 is detected in the plurality of captured images P of the other side surface Ws2 in the same manner as the side surface Ws1 (step S3).

Then, the image processing unit 60 calculates the sharpness value of the detected first characteristic portion Wc1 in the first focus degree evaluation unit 62, and evaluates the degree of focus of the first characteristic portion Wc1 for each captured image P. (Step S4).

Then, the image processing unit 60 causes the first reference image selection unit 63 to select, from the plurality of captured images P, the captured image P with the highest degree of focus of the first characteristic portion Wc1 as the first reference image Ps1. Furthermore, a captured image P other than the captured image P selected as the first reference image Ps1 is set as a test image Pt (step S5).

Then, the image processing unit 60 sets a characteristic region Rc in the first standard image Ps1 so as to include the first characteristic portion Wc1, and sets a region to be inspected Ri in the inspection image Pt in the region setting unit 64 (step S6).

Then, the image processing section 60 extracts the image data p of the characteristic region Rc set in the first reference image Ps1 and the image data p of the inspected region Ri set as the inspection image Pt in the synthesis section 65 (step S7). . Furthermore, the synthesizing unit 65 creates a composite image CP of the side surfaces Ws1 and Ws2 of the workpiece W by connecting the image data p of the characteristic region Rc and the inspected region Ri extracted from the first reference image Ps1 and the inspection image Pt ( Step S8).

In addition, regarding the plurality of captured images P generated by capturing the other side surface Ws2 by the side surface imaging device 32 in step S2, the same processing as that for the captured image P of the side surface Ws1 is performed separately for the captured image P of the side surface Ws1 to create a composite image CP. Create. In other words, for the captured image P of the side surface Ws2, the detection of the first feature Wc1 (step S3), the evaluation of the degree of focus of the first feature Wc1 (step S4), and the detection of the first reference image Ps1 and the inspection image Pt are performed. selection (step S5), setting of the characteristic region Rc and the region to be inspected Ri (step S6), extraction of image data p of the characteristic region Rc and the region to be inspected Ri (step S7), and creation of a composite image CP (step S8) is executed.

Then, the image processing unit 60, in the evaluation unit 66, performs an external appearance inspection of the side surfaces Ws1 and Ws2 of the workpiece W to check for scratches, dirt, etc., based on the composite image CP generated in the composition unit 65 (step S9). ).

(4) Effects If the optical axes L1, L2 of the side imaging devices 31, 32 are tilted with respect to the side surfaces Ws1, Ws2 of the work W, an image may be obtained in which only a portion of the vertical direction Z is focused. . In the appearance inspection apparatus 1 of this embodiment, even if the captured image P is an image in which only a portion of the vertical direction Z is focused, only the focused area is extracted from each captured image P, and the workpiece is inspected with high resolution. A side image can be obtained. Therefore, it is possible to obtain high-resolution images of the side surfaces Ws1 and Ws2 of the workpiece W while suppressing damage to the workpiece W during transport.

In addition, in the appearance inspection apparatus 1 of the present embodiment, the first reference image Ps1 is selected from the plurality of captured images P based on the first characteristic part that makes it easy to evaluate the degree of focus, and the first reference image Ps1 is selected from among the first reference images Ps1. A feature region Rc, which is an in-focus region, is extracted. Furthermore, based on the position of the feature region Rc in the first reference image Ps1, an in-focus region Ri is extracted from each inspection image Pt other than the first reference image Ps1, and the extracted feature region Rc Then, the side surfaces Ws1 and Ws2 of the workpiece W are evaluated based on the image data p of the region Ri to be inspected.

Therefore, in the appearance inspection device 1, even if there is an image among the plurality of captured images P that has little change in brightness value and makes it difficult to evaluate the degree of focus, it is possible to It is possible to specify an in-focus area from among the captured images whose focus is difficult to evaluate, and it is possible to obtain images of the side surfaces Ws1 and Ws2 of the workpiece W with high resolution.

In the appearance inspection apparatus 1 of the present embodiment, a side imaging device 31 that images one side surface Ws1 of the workpiece W and a side imaging device 32 that images the other side surface Ws2 move vertically integrally while Since the side surfaces Ws1 and Ws2 of the workpiece W are imaged synchronously, a plurality of images whose imaging ranges differ by the imaging pitch D can be imaged from the two side surfaces Ws1 and Ws2 of the workpiece W with a simple configuration.

Moreover, in the appearance inspection apparatus 1 of the present embodiment, the image processing unit 60 separately processes the captured image P of one side surface Ws1 and the captured image P of the other side surface Ws2 of the workpiece W to generate a composite image CP. Even if side surfaces Ws1 and Ws2 of the workpiece W are imaged synchronously, the dimensional tolerance of the workpiece W can be corrected and the composite image CP can be created.

(5) Modification Examples The embodiments of the present invention have been described above, but these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, substitutions, and changes can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and gist of the invention as well as within the scope of the invention described in the claims and its equivalents. An example of the change will be explained below. Note that any one of the plurality of modification examples described below may be applied to the above embodiment, or any two or more of the modification examples described below may be applied in combination. It's okay. Note that various changes are possible in addition to the following example of change.

(5-1) Change example 1
Next, a first modification of the above embodiment will be described with reference to FIGS. 9 to 12. Note that components having the same configuration as those of the above-described embodiment are given the same reference numerals, and explanations of the configurations will be omitted.

When the side surfaces Ws1 and Ws2 of the workpiece W placed on the stage 2 are inclined with respect to the vertical direction Z, the imaging ranges of the side surfaces Ws1 and Ws2 of the workpiece W by the side imaging devices 31 and 32 differ in the vertical direction Z. When the captured images P are compared, the area in focus in the captured images P changes. In other words, when the side surfaces Ws1 and Ws2 of the workpiece W are inclined with respect to the vertical direction Z and are not parallel to the moving direction of the side imaging devices 31 and 32, the position of the inspected region Ri in the inspection image Pt is It deviates from the position of the characteristic region Rc in the image Ps1.

In this modified example, a second characteristic portion Wc2 is detected in addition to the first characteristic portion Wc1 from the captured image P, and an area to be inspected Ri that occurs when the side surfaces Ws1 and Ws2 of the workpiece W are inclined with respect to the vertical direction Z The positional deviation of is corrected based on the first characteristic portion Wc1 and the second characteristic portion Wc2.

Specifically, as shown in FIG. 9, the image processing section 60 includes a second feature detection section 67, a second focus evaluation section 68, a second reference image selection section 69, and a correction section 70. There is.

The second feature detection unit 67 detects a second feature Wc2 different from the first feature Wc1 from all or some of the plurality of n captured images P stored in the storage device 52.

Note that the second feature detection unit 67 may detect the second characteristic portion Wc2 for all of the plurality of n captured images P stored in the storage device 52, or may detect the second feature Wc2 for all of the plurality of n captured images P. The second characteristic portion Wc2 may be detected for a portion of the captured image P.

The second characteristic portion Wc2 may be a pattern or a mark provided on the side surfaces Ws1, Ws2 of the workpiece W, a pattern or a mark provided on the side surfaces Ws1, Ws2 of the workpiece W, etc. at a different position in the vertical direction Z from the first characteristic portion Wc1. Any part of the side surfaces Ws1 and Ws2 of the workpiece W can be used as the second characteristic part Wc2, as long as the second characteristic part 68 can evaluate the degree of focus. In this modified example, the second feature detection unit 67 detects the lower end E2 of the side surface Ws1 and Ws2 of the workpiece W as the second feature Wc2.

The second focus evaluation section 68 evaluates the focus degree of the second feature portion Wc2 detected by the second feature detection section 67. As with the method for evaluating the degree of focus of the second characteristic portion Wc2, various methods can be adopted, similar to the evaluation of the degree of focus of the first characteristic portion Wc1. For example, the second characteristic detection unit 67 The sharpness value of the second feature Wc2 is calculated for each captured image P in which the feature Wc2 is detected, and the captured image with a larger sharpness value is evaluated as an image with a higher degree of focus.

The second reference image selection section 69 selects one image with the highest degree of focus from the captured images P evaluated by the second degree of focus evaluation section 68 as the second reference image Ps2.

The correction unit 70 specifies the position of the first characteristic portion Wc1 in the first reference image Ps1 and the position of the second characteristic portion Wc2 in the second reference image Ps2.

For example, as shown in FIG. 10, the correction unit 70 specifies the position of the first characteristic portion Wc1 by specifying the number of pixels Nc1 in the vertical direction Z from the upper end of the first reference image Ps1 to the first characteristic portion Wc1. do. Further, as shown in FIG. 11, the correction unit 70 specifies the position of the second characteristic portion Wc2 by specifying the number of pixels Nc2 in the vertical direction Z from the upper end of the second reference image Ps2 to the second characteristic portion Wc2. do.

The correction unit 70 calculates the amount of positional deviation ΔQ that occurs in the area to be inspected Ri set in the m-th captured image Pm by the area setting unit 64 using equation (5), and adjusts the area to be inspected Ri by the calculated amount of positional deviation ΔQ. By moving in the vertical direction Z, a corrected region to be inspected Ri′ is set by correcting the region to be inspected Ri of the m-th captured image Pm.

式（５）において、Ｎｃ１は第１基準画像Ｐｓ１の上端から第１特徴部Ｗｃ１までの上下方向Ｚの画素数、Ｎｃ２は第２基準画像Ｐｓ２の上端から第２特徴部Ｗｃ２までの上下方向Ｚの画素数、ｎｓ１は第１基準画像Ｐｓ１の順序数、ｎｓ２は第２基準画像Ｐｓ２の順序数、ｍは被検査領域Ｒｉを補正する検査画像Ｐｔの順序数である。

In equation (5), Nc1 is the number of pixels in the vertical direction Z from the top of the first reference image Ps1 to the first feature Wc1, and Nc2 is the number of pixels in the vertical direction Z from the top of the second reference image Ps2 to the second feature Wc2. , ns1 is the ordinal number of the first reference image Ps1, ns2 is the ordinal number of the second reference image Ps2, and m is the ordinal number of the inspection image Pt for correcting the area to be inspected Ri.

The correction unit 70 performs such setting of the corrected inspection area Ri' for all inspection images Pt (that is, captured images P other than the first reference image Ps1 and the second reference image Ps2).

In this modification example, it is possible to correct the positional deviation of the inspection area Ri that occurs when the side surfaces Ws1 and Ws2 of the workpiece W are inclined with respect to the vertical direction Z, and it is possible to obtain a high-resolution image. .

Note that the correction of the inspection area Ri as in this modification example may be executed when the visual inspection device 1 is operated for the first time, when the type of workpiece W is changed, or every time the workpiece W is inspected. or can be executed at any time.

(5-2) Change example 2
In the above embodiment, a case has been described in which the first feature detection section 61 detects the first feature Wc1 for all of the plurality of n captured images P stored in the storage device 52. Detection of the first characteristic portion Wc1, evaluation of the degree of focus, and selection of the first reference image Ps1 may be performed for a portion of the captured image P of the captured image P.

For example, the image processing unit 60 selects a captured image in which the first characteristic portion Wc1 is captured, or a portion of the captured image in which the first characteristic portion Wc1 is expected to be captured, among the plurality of n captured images P. For the images P (for example, the first to tenth captured images P1 to P10), detection of the first characteristic portion Wc1, evaluation of the degree of focus, and selection of the first reference image Ps1 may be performed.

Further, the image processing unit 60 detects the first characteristic portion Wc1 and evaluates the degree of focus every predetermined number (for example, 10) of the plurality of n captured images P, and the captured image in which the degree of focus has been evaluated. The captured image P with the highest degree of focus (eg, the 11th captured image P11) and the captured image P with the second largest degree of focus (eg, the 21st captured image P21) are determined. Then, the first characteristic portion Wc1 is applied to all or some of the captured images P captured between the determined two captured images (for example, the 12th to 20th captured images P12 to P20). Detection, evaluation of the degree of focus, and selection of the first reference image Ps1 may be performed.

As in this modification example, by detecting the first characteristic portion Wc1, evaluating the degree of focus, and selecting the first reference image Ps1 for a portion of the captured image P of the plurality of n captured images P, , processing load can be reduced.

(5-3) Change example 3
In the embodiment described above, the appearance inspection of the side surfaces Ws1 and Ws2 of the workpiece W was performed based on the composite image CP obtained by joining the image data p of the characteristic region Rc and the region to be inspected Ri. First, the appearance inspection of the side surfaces Ws1 and Ws2 of the workpiece W may be performed based on the image data p of the characteristic region Rc and the region to be inspected Ri.

1... Appearance inspection device 2... Stage 3... Imaging section 4... Moving mechanism 5... Control device 31... Side imaging device 32... Side imaging device 33... Top imaging device 41... Holding base 51... Processing device 52... Storage device 53... Device Control section 54...Data acquisition section 60...Image processing section 61...First feature detection section 62...First focus evaluation section 63...First reference image selection section 64...Region setting section 65...Composition section 66...Evaluation section

Claims (5)

an imaging device that captures a side view of the workpiece to generate a captured image;
a moving mechanism that moves the imaging device along a side surface of the workpiece;
An appearance inspection device comprising: an image processing unit that performs image processing on the captured image;
The imaging device captures images of side surfaces of the workpiece at a plurality of different positions moved by the moving mechanism to obtain a plurality of captured images,
The image processing unit includes:
a first feature detection process that detects a first feature from the captured image;
a first focus degree evaluation process that evaluates the focus degree of the first characteristic portion;
a first reference image selection process of selecting one of the plurality of captured images as a first reference image by comparing the degree of focus of the first characteristic portion in the plurality of captured images;
A characteristic region that is an area including the first characteristic part in the first reference image, and an area in the captured image other than the first reference image that is located at a position occupied by the characteristic region in the first reference image. An appearance inspection device that performs an evaluation process of evaluating the workpiece based on inspection areas provided at corresponding positions . The image processing unit selects some of the plurality of captured images as the first reference image by comparing the degree of focus of the first characteristic portion in the first reference image selection process. The appearance inspection device according to claim 1. The external appearance inspection apparatus according to claim 1, wherein the image processing unit executes a synthesis process that connects the feature area and the inspection area to generate a composite image representing a side surface of the workpiece. comprising a plurality of the imaging devices,
The external appearance inspection apparatus according to claim 1, wherein a plurality of said imaging devices are moved together by said moving mechanism along said side surface, and image said side surface in synchronization to obtain a plurality of said captured images, respectively. . The image processing unit includes:
a second feature detection process that detects a second feature that is different from the first feature from the captured image;
a second focus degree evaluation process that evaluates the focus degree of the second characteristic portion;
a second reference image selection process of selecting one of the plurality of captured images as a second reference image by comparing the degree of focus of the second characteristic portion in the plurality of captured images;
2. A correction process for correcting the inspection area based on the position of the first characteristic part in the first reference image and the position of the second characteristic part in the second reference image. The appearance inspection device described.

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