JP4837541B2 - End face shape inspection method and apparatus - Google Patents

Description

  The present invention relates to a method for inspecting the shape of an end surface of a cylindrical body or columnar body such as a photosensitive drum base of a copying machine, for example.

  It is conceivable to measure the shape, dimensions, etc. of various measured objects based on images obtained by photographing the measured object with a camera.

  When a three-dimensional object is photographed with a lens, distortion occurs in which the periphery is larger or bent than the center of the image. In order to cope with such distortion, for example, Patent Document 1 below proposes a method of removing distortion by changing the magnification between the center and the periphery of an image. In Patent Document 2 below, a method is proposed in which a laser is projected onto a measurement object parallel to the camera axis, and the positional relationship between captured images is measured using the laser information as a reference.

In Patent Document 3 below, image collation is performed by comparing a camera image of a target object in a real space and an image verification data data that is a database of a plurality of model images obtained by imaging various three-dimensional postures of the target object. A method for correcting a three-dimensional posture in model image matching for estimating a three-dimensional posture of a target object in real space is disclosed. In this document, it is proposed to rotationally correct a provisionally estimated three-dimensional posture based on a line-of-sight difference between the center of gravity of a camera image and a model image.
JP-A-11-161779 JP 2006-23262 A JP 2004-362128 A

  However, conventionally, no method has been proposed for accurately measuring the shape of the end of the object to be measured based on the image captured by the camera, regardless of the relatively expensive three-dimensional measurement device using the trigonometric method.

  In other words, if the object to be measured does not have a height (depth) in the camera axis direction, detecting the position of the contour line of the object to be measured in the captured image will only correct the distortion of the lens. The position can be obtained.

  However, in a normal camera having an angle of view, the shooting angle varies depending on the position in the captured image. Therefore, in the case of a measured object having a height in the camera axis direction, depending on the relationship between the shooting angle and the shape of the end, There is a possibility that parts having different height positions constituting the image are photographed.

  For this reason, when the position to be measured for each object to be measured is not constant, or the dimensions and shape are different, the photographing angle condition differs for each photographing opportunity, and depending on the condition, the error becomes large and an accurate shape cannot be detected. The problem arises.

  The present invention has been made in view of the above problems, and an inspection method or the like that can easily and accurately evaluate the shape of an end surface of a measured object even if the measured object has a height in the camera axis direction. The purpose is to provide.

In order to solve the above problems, the present invention provides the following means. That is,
[1] An end surface of a cylindrical or columnar object to be measured is photographed with a camera having an angle of view from a direction substantially parallel to the end surface;
Detect the outermost contour of the end face of the measured object from the captured image,
End face shape inspection method, wherein the shape of the end face is evaluated based on whether or not the detected curve shape of the outermost contour line is a curved shape corresponding to the position of the outermost contour line in the captured image .

[2] Calculate a curve shape when an outermost contour line of an ideal perfect circular shape is detected at a position in the captured image of the detected outermost contour line,
The end face shape inspection method according to item 1 above, wherein the shape of the end face of the measured object is evaluated by comparing the detected curve shape of the outermost outline with the curve shape of the outermost outline of the ideal end face. .

  [3] The above item 2 for evaluating the shape of the end face of the measured object by comparing the detected image of the curved shape of the outermost contour line with the image of the curved shape of the outermost contour line of the ideal end face. The end face shape inspection method according to 1.

  [4] By comparing a predetermined index value as an index of the detected curve shape of the outermost contour line with the index value of the curve shape of the outermost contour line of the ideal end face, 3. The end face shape inspection method according to item 2 above, wherein the end face shape is evaluated.

  [5] The end position measuring method according to any one of the above items 1 to 4, wherein the object to be measured is irradiated with backlight illumination to perform imaging.

[6] While evaluating the shape of the end face,
According to the position of the detected outermost contour line in the captured image, determine the height position of the part imaged as the outermost contour line,
By correcting the position of the outermost contour line in the captured image in accordance with the height position of the outermost contour line, the camera axis of the end face of the measurement object being photographed as the outermost contour line 6. The end face shape inspection method according to any one of items 1 to 5, wherein a position in a direction intersecting the direction is calculated.

  [7] The end face shape inspection method according to [6], wherein a length dimension of the measurement object is calculated based on the calculated position of the end face of the measurement object.

“8” Photograph both end faces of the object to be measured,
While evaluating the shape of both end faces based on this captured image,
Calculate the position of both end faces based on this captured image,
8. The end face shape inspection method according to item 7, wherein the length dimension of the measurement object is calculated based on the calculated positional relationship between both end faces.

  [9] The end face shape inspection method according to item 8 above, wherein both positions of the object to be measured are photographed by different cameras and each position is calculated.

  [10] The end face shape inspection method according to any one of [1] to [9], wherein the measurement target is a photosensitive drum substrate.

[11] An imaging means for imaging an end face of a cylindrical or columnar object to be measured with a camera having an angle of view from a direction substantially parallel to the end face;
Contour detection means for detecting the outermost contour of the end face of the object to be measured from the captured image;
End face shape evaluation means for evaluating the shape of the end face depending on whether or not the detected curve shape of the outermost contour line is a curved shape according to the position of the outermost contour line in the captured image;
An end face shape inspection apparatus comprising:

[12] A height position determining unit that determines a height position of a part imaged as the outermost contour line according to the position of the detected outermost contour line in the captured image;
By correcting the position of the outermost contour line in the captured image in accordance with the height position of the outermost contour line, the camera axis of the end face of the measurement object being photographed as the outermost contour line End position calculating means for calculating a position in a direction intersecting the direction;
12. The end face shape inspection apparatus according to 11 above, comprising:

  According to the above invention [1], it is determined whether or not the detected outermost contour curve shape is a curve shape corresponding to the position in the photographed image, that is, the photographing angle. Therefore, even when the measured object has a height in the camera axis direction, and there is a possibility that a part with a different height position constituting the end depending on the imaging angle may be imaged, the shape of the end face is accurately Can be evaluated. In addition, it is possible to easily inspect based on an image captured by a normal camera having an angle of view. In addition, since the outermost contour line is used as a detection target, it can be detected with high reliability.

  According to the above invention [2], in order to compare the detected outermost contour line with the curved shape of the outermost contour line of the ideal perfect circular end surface, the evaluation based on the difference from the ideal end surface is performed. Can do.

  According to the invention [3], since the detected outermost contour line is compared with an ideal end face image, it is possible to perform detailed evaluation on each part of the end face.

  According to the above invention [4], since the detected outermost contour line is compared with the index value of the ideal end face, the end face shape can be more easily evaluated.

  According to the above invention [5], the outermost contour line can be detected more accurately.

  According to the above invention [6], not only the shape of the end face but also the position of the end face can be evaluated from the result of photographing the end face of the measured object.

  According to the above invention [7], it is possible to evaluate not only the shape of the end face but also the length dimension of the measured object from the result of photographing the end face of the measured object.

  According to the invention [8], since both end faces are photographed, the shape of both end faces can be evaluated, and the length dimension can be measured regardless of the position of the measurement object at the time of photographing.

  According to the invention [9], each camera can be fixed at a position where each end face of the measured object is included in the photographing range, so that the camera position is stabilized and accurate shape evaluation and length dimension measurement are performed. It can be carried out.

  According to the invention [10], it is possible to contribute to the supply of the photosensitive drum substrate having the required end face shape accuracy.

  According to the above invention [11], it is determined whether or not the detected outermost contour curve shape is a curve shape corresponding to the position in the captured image, that is, the imaging angle. Therefore, even when the measured object has a height in the camera axis direction, and there is a possibility that a part with a different height position constituting the end depending on the imaging angle may be imaged, the shape of the end face is accurately Can be evaluated. In addition, it is possible to easily inspect based on an image captured by a normal camera having a field angle. In addition, since the outermost contour line is used as a detection target, it can be detected with high reliability.

  According to the above invention [12], not only the shape of the end face but also the position of the end face can be evaluated from the result of photographing the end face of the measured object.

  Hereinafter, the present invention will be described based on embodiments.

  FIG. 1 is an explanatory diagram of an end face shape inspection apparatus that performs an end face shape inspection method for an object to be measured according to the present invention.

  Here, a case where a cylindrical body used as a photosensitive drum substrate is a measurement object 90 and its end face shape and the length dimension are measured is taken as an example. Both end surfaces of the cylindrical body as the measurement target 90 are flat and perpendicular to the length direction of the measurement target 90. Such a three-dimensional object to be measured 90 has a height in any shooting direction.

  The inspection apparatus includes cameras 10 and 10 that respectively photograph both end portions 91 and 91 of the measured object 90, and image processing that performs evaluation calculation of an end surface shape of the measured object 90 based on images captured by the cameras 10 and 10. The apparatus 20 includes illumination apparatuses 30 and 30 that irradiate backlight illumination from behind the object to be measured 90 when viewed from the camera 10 and 10 side.

  The cameras 10 and 10 have an angle of view θ. For this reason, the photographing angle with respect to each part of the subject (measured object) 90 can be changed depending on the position of the photographed image. In this embodiment, a two-dimensional camera that captures a two-dimensional image is employed as the cameras 10 and 10.

  The cameras 10 and 10 capture a captured image that can detect the outermost contour lines of the end portions 91 and 91 of the measurement object 90. Here, in the present invention, the outermost contour line means that the outermost contour line as viewed from the camera 10 is formed by each part constituting the measured object 90.

  In this embodiment, the cameras 10 and 10 are provided with a plurality of units (two units) at positions aiming at both end portions 91 and 91 of the measured object 90, respectively, while the plurality of measured objects 90 are sequentially inspected. The position is fixed.

  The cameras 10 and 10 aim at both end portions 91 and 91 of the measured object 90 from directly above when the measured object 90 according to the ideal design dimensions is placed at an ideal position. Placed in position. Specifically, it is a position where each camera axis 11, 11 is located on a plane including each end face of the measurement object 90. At this time, the camera shaft 11 is parallel to each end face. Here, in the present invention, the camera axis 11 refers to a straight line connecting the center of the camera 10 and the center of the captured image.

  Thus, in the case of the ideal measured object 90, the position setting of the cameras 10 and 10 that the end surfaces of the measured objects coincide with the camera axes 11 and 11 of both the cameras 10 and 10 is, for example, an ideal master work. Can be realized by adjusting the camera position so that both ends thereof are on the camera axes 11 and 11.

  Further, since the cameras 10 and 10 are arranged at positions where the both end portions 91 and 91 of the measured object 90 are aimed from directly above, the position and length dimension of the end portion 91 of the measured object 90 to be measured are determined. The direction is orthogonal to the camera axes 11 and 11.

  The cameras 10 and 10 function as photographing means for photographing the measured object 90 having a height in the camera axial direction.

  The illuminating devices 30 and 30 are configured using an arbitrary light source such as a fluorescent lamp or an LED, and in the captured images of the cameras 10 and 10, the outermost contour lines of the end portions 91 and 91 of the measured object 90 are used as silhouette images. It is something that can clearly emerge. By using such backlight illumination, the outermost contour line of the measurement object 90 can be detected more accurately.

  The image processing apparatus 20 includes, for example, a computer having a CPU, a memory, an external storage device, an input unit such as a keyboard and a mouse, an output unit such as a monitor, and an input / output interface with other devices. As will be described later, the image processing apparatus 20 functionally includes contour detection means, end face shape evaluation means, height position determination means, end position calculation means, and dimension calculation means.

  The image processing apparatus 20 evaluates the shape of both end surfaces based on the captured images of both end portions 91 and 91 of the measurement object 90, and outputs the inspection result determined to be acceptable.

  In parallel, the image processing apparatus 20 calculates these positions based on the captured images of the both end portions 91 and 91 of the measured object 90, and further, based on the calculated positions of the both end portions 91 and 91. The distance between both end portions 91 and 91 is calculated as the length dimension of the measured object 90 and output.

  The normal cameras 10 and 10 having an angle of view as used in the present invention have different shooting angles with respect to the subject depending on the position in the shot image.

  For this reason, in the case of the measurement object 90 having a height in the camera axis direction, the parts having different height positions constituting the end portions 91 and 91 are photographed depending on the relationship between the photographing angle and the shape of the end portions 91 and 91. There is a possibility.

  For example, as in the example of the present embodiment, when the end portions 91 and 91 of the measured object 90 have end faces parallel to the camera axis 11, there are shooting angles at which the end faces can be seen and shooting angles at which the end faces cannot be seen. When the end surface is visible, the lower edge (the side far from the camera 10) of the end surface is photographed as the outermost contour line of the end portion. On the other hand, when the end face cannot be seen, the outermost contour line being photographed is photographed with the upper edge (side closer to the camera 10) of the end face as the outermost contour line of the end portion.

  Furthermore, even when the same upper edge or lower edge is photographed, the curve shape of the outermost contour line photographed differs depending on the position in the photographed image, that is, the photographing angle.

  In the end face shape inspection, the image processing apparatus 20 according to the present embodiment determines at what shooting angle the outermost contour line of the end portion of the measurement object 90 is shot, and in each case. Accordingly, the shape of the end surface appearing on the outermost contour line photographed is evaluated.

  Further, the image processing apparatus 20 according to the present embodiment discriminates a case in which a part having a different height position constituting the end of the measurement object 90 is detected in the length dimension measurement, If necessary, the position of the outermost contour line detected in the captured image is corrected to bundle the measurement of the end position of the measured object and the position measurement results of both end portions 91 and 91 of the measured object 90. It is designed to accurately measure the length dimension.

  In the following, first, the end face shape inspection process performed in the image processing apparatus 20 will be described based on an example in which the left end of the measurement object 90 is a measurement target.

  FIG. 2A is an explanatory diagram illustrating a case where the end 91 of the measurement target 90 is photographed in a positional relationship where the camera shaft 11 is positioned on a plane including the end surface 92 of the measurement target 90. FIG. b) is an example of the captured image 12 in that case. Here, an object to be measured 90 having an ideal perfect circular end surface is assumed. The same applies to FIGS. 3 and 4 described later.

  The positional relationship in which the camera shaft 11 is positioned on a plane including the end surface 92 of the measured object 90 is a state in which the camera 10 is positioned directly above the end surface 92 as shown in FIG.

  At this time, as shown in FIG. 4B, the end surface 92 of the measured object 90 is in a straight line shape on the photographed image 12 so that all the portions including the upper edge and the lower edge at different height positions are aligned. Thus, it is shown as the outermost contour that forms the silhouette of the measurement object 90. That is, the outermost contour line is located at the exact center in the captured image 12.

  FIG. 3A is an explanatory diagram illustrating a case where the end 91 of the measurement target 90 is photographed in a positional relationship in which the camera shaft 11 is positioned outside a plane including the end surface 92 of the measurement target 90. FIG. (B) is an example of a photographed image in that case.

  The positional relationship in which the camera shaft 11 is positioned outside the plane including the end surface 92 of the measured object 90 is the longitudinal direction of the measured object 90 from directly above the end surface 92 as shown in FIG. It is in a state where it is located on the outside of the direction (further left outside the left end) and at a shooting angle at which the end face 92 can be seen.

  At this time, as shown in FIG. 5B, the end surface 92 of the measured object 90 appears in the captured image 12 as an ellipse having a certain area, and the lower edge 93 of the end surface 92 is the silhouette of the measured object 90. Is shown on the right half side of the photographed image 12 as the outermost contour line. That is, the outermost contour line is located in the right half surface area in the captured image 12.

  The outermost contour line has a curved shape corresponding to the position in the photographed image 12, that is, the photographing angle, and appears in the photographed image 12.

  4A is an explanatory diagram illustrating a case where the end 91 of the measurement target 90 is photographed in a positional relationship in which the camera shaft 11 is positioned inside a plane including the end surface 92 of the measurement target 90. FIG. (B) is an example of a photographed image in that case.

  The positional relationship in which the camera shaft 11 is positioned on the inner side of the plane including the end surface 92 of the device under test 90 is the longitudinal direction of the device under test 90 from directly above the end surface 92 as shown in FIG. This is a state where the photographing angle is located inside the direction and the end face 92 is not visible.

  At this time, as shown in FIG. 4B, the end surface 92 of the measurement object 90 is not shown in the photographed image 12, and the upper edge 94 of the end surface 92 is the outermost contour line that forms the silhouette of the measurement object 90. This is shown on the left half side of the photographed image 12. That is, the outermost contour line is located in the left half surface area in the captured image 12.

  The outermost contour line has a curved shape corresponding to the position in the photographed image 12, that is, the photographing angle, and appears in the photographed image 12.

  Even in the case of an ideal perfect circular end face, the appearance (curved shape) varies depending on the photographing angle. However, in the case of an ideal perfect circular end face, the appearance (curved shape) is uniquely determined by the shooting angle.

  On the other hand, if the end face is not an ideal perfect circular shape, an outermost contour line different from the ideal perfect circular shape described above is detected.

  FIG. 5A is an explanatory diagram showing a case where a flat end face-shaped object to be measured with a narrow vertical width is photographed, and FIG. 5B is an example of a photographed image in that case. In the figure, the ideal end face is shown with a broken line. The same applies to FIGS. 6 to 8 described later.

  The end face shape of the measurement object 90 in this example is shown on the right side of FIG.

  In the case of such an end face shape, as shown in FIG. 5B, the curve shape of the outermost contour line of the end face 92 in the photographed image 12 is more than the end face 92 than the outermost contour line (broken line) of the ideal end face. Since the width of the end face 92 is increased, the end face 92 is lowered and the length of the end face 92 is reduced.

  FIG. 6A is an explanatory diagram showing a case where a measured object having a flat end face shape with a narrow lateral width is photographed, and FIG. 6B is an example of a photographed image in that case.

  The end face shape of the measurement object 90 in this example is shown on the right side of FIG.

  In the case of such an end face shape, as shown in FIG. 5B, the curve shape of the outermost contour line of the end face 92 in the photographed image 12 is more than the end face 92 than the outermost contour line (broken line) of the ideal end face. Is short because it is narrow, and because the height of the end surface 92 is high, it draws a large curve that is bent.

  FIG. 7A is an explanatory view showing a case where an end face-shaped object to be measured which is not perpendicular to the longitudinal direction is photographed in a posture in which the end face is obliquely upward, and FIG. 7B is a photograph in that case. It is an example of an image. Here, the cross section of the object to be measured is assumed to be a perfect circle.

  In this example, since the end surface 92 is located almost directly below the camera shaft 11 as shown in FIG. 5A, a linear outermost contour line should be visible in the captured image 12 if it is an ideal end surface. It is. However, since the end face 92 has a shape that is cut obliquely, the outermost contour line of the end face 92 has an elliptical curved shape as shown in FIG.

  FIG. 8A is an explanatory view showing a case where an end face-shaped object to be measured which is not perpendicular to the longitudinal direction is photographed in a posture in which the end face is oriented in the horizontal direction, and FIG. 8B is a photograph in that case. It is an example of an image. Here, the cross section of the object to be measured is assumed to be a perfect circle.

  In this example, since the end surface 92 is located almost directly below the camera shaft 11 as shown in FIG. 4A, a straight line orthogonal to the longitudinal direction of the measured object 90 is used in the captured image if it is an ideal end surface. The outermost contour line should be visible. However, since the end face 92 has an obliquely cut shape, the outermost contour line of the end face 92 has a linear shape extending obliquely with respect to the longitudinal direction of the measured object, as shown in FIG. Yes.

  As described above, in the case of the measurement target 90 that does not have an ideal end surface, the outermost contour line of the end surface 92 in the captured image 12 is elliptical or straight depending on the shape of the end surface 92 and the positional relationship with the camera 10. However, it is different from the outermost contour of the ideal end face.

  Therefore, in this embodiment, first, the photographing angle (position in the photographed image) is obtained for the photographed outermost contour line, and the appearance (curved shape) when an ideal end face is photographed at the same photographing angle is obtained. calculate. By comparing the ideal curve shape calculated in this way with the shape of the outermost contour actually photographed, the end face shape is inspected regardless of the angle of photographing with respect to the actual measured object. It has become something that can be done.

  Specifically, in the case where the photographed image 12 shown in FIG. 5B is obtained as an example, the outermost contour line of the end face 92 is detected from this image 12 and, for example, the measurement of the leftmost line 96 is performed. The position of the body 90 in the longitudinal direction (distance from the camera axis 11) is set as the position of the outermost contour line. Then, the curve shape of the outermost contour line when the outermost contour line of the measurement object having an ideal end face is detected at this position is calculated.

  As the data format of the curve shape of the outermost contour line of the ideal end face calculated in this way, for example, image data that can be collated with a photographed image can be cited.

  Such image data can be obtained by calculating the position of the outermost contour line in the captured image from the geometrical positional relationship between the ideal end face and the camera and forming an image. Alternatively, the curve shape of the outermost contour line for each position may be stored as image data for a large number of position candidates of the outermost contour line, and extracted from them.

  As an image in which the curved shape of the outermost contour line of the ideal end surface appears, for example, the captured image 12 of FIG. 3B is obtained.

  If an image having a curved shape of the ideal end face is obtained in this way, it is compared with a photographed image obtained by photographing the measured object 90 (here, FIG. 5B). In this case, since the images are compared with each other, the degree of difference can be calculated by any known image matching method.

  And if the degree of this difference is within a range acceptable as an acceptable product, the end face of the measured object 90 is evaluated as acceptable, and conversely, if it is out of range, it is evaluated as unacceptable. do it. Thus, when comparing by image collation, detailed evaluation can be performed for each part of the end face.

  The data format representing the curve shape of the outermost contour line of the ideal end face can be a mathematical expression that can specify the curve shape, or coordinate value data of several points on the curve shape. With such a data format, it is possible to reduce the amount of calculation required to create (calculate) ideal end face data.

  The comparison with the outermost contour line in the actual captured image of the object to be measured is the same as the data format of the ideal end face from the outermost contour line of the actual captured image when the data format cannot be directly matched. This can be done by calculating the data shown and comparing the two.

  Further, the curve shape of the outermost contour line of the ideal end face may be expressed with a predetermined index value serving as the index. In this case, the index value may be such that the entire curve shape cannot be specified by itself. Specifically, the curvature (or radius of curvature) of a specific part in the outermost contour line, the inclination of the specific part in the outermost contour line (for example, the angle formed with the longitudinal direction of the measured object), the outermost contour The length of the curve of the line, the width of the outermost contour line, the height of the outermost contour line (depth of the dent of the curve), the ratio of the width and height of the outermost contour line, or the average curvature of the outermost contour line (Or average radius of curvature).

  The comparison with the outermost contour in the actual captured image of the object to be measured can be performed by calculating the same index value as the ideal end face from the outermost contour of the actual captured image and comparing the two. it can.

  In this way, when compared with the index value, the end face shape can be more easily evaluated.

  Next, the calculation processing of the position of the end portion 91 performed in the image processing apparatus 20 will be described based on an example in which the left end portion of the measurement object 90 is a measurement target.

  Unlike the above-described shape evaluation compared with the ideal end face when viewed in the same manner, when measuring the length dimension of the object to be measured, it is necessary to determine the position of the end face so that it can be evaluated numerically.

  However, for example, in the example of FIG. 3 described above, the lower edge 93 of the end surface 92 is photographed as the outermost contour line. Here, in the photographed image 12, the positional relationship between the position in the image 12 and the real space is shown. Assuming that the conversion is based on the center height of the measured object 90 (hereinafter, this height is referred to as a reference height), the end face 92 in the length direction of the measured object 90 (the left-right direction in FIG. 3). This position should be detected as the line 95 in FIG.

  In the example of FIG. 4 described above, the upper edge 94 of the end surface 92 is photographed as the outermost contour line. Here, in the photographed image 12, the positional relationship between the position in the image 12 and the real space is converted. Assuming that the center height (reference height) of the measured object 90 is used as a reference, the position of the end face 92 in the length direction (left and right direction in FIG. 4) of the measured object 90 is as shown in FIG. It can be said that it should be detected as line 95.

  In this way, depending on the positional relationship between the position of the end 91 of the measured object 90 and the camera axis 11, the measured object 90 detected as the outermost contour line in the right half and the left half of the captured image 12 is shown. The site | parts of the edge part 91 differ, and the height position of these each site | part differs.

  Even if the upper edge and the lower edge having different height positions are detected at the same distance from the center of the screen in the shooting screen, the positions of the end portions in each case (camera axis) The distance from is not the same.

  Therefore, in this embodiment, the height position of the part detected as the outermost contour line is determined based on the region in the captured image where the outermost contour line is detected, and correction according to the height position is performed. The exact position of the end is calculated by.

  Next, an example of a specific formula for calculating the end position will be described.

  FIG. 9 illustrates a method for calculating the end position when the end 91 of the measured object 90 is photographed in a positional relationship where the camera shaft 11 is positioned outside the plane including the end surface 92 of the measured object 90. It is explanatory drawing. In the figure, the captured image 12 of the camera 10 is represented below the measured object 90.

  In this example, the measured object 90 is in a position in which the end surface 92 of the measured object 90 is away from the measured object 90 by a distance L from the camera axis 11. In this positional relationship, as described above, the lower edge 93 of the end surface 92 is imaged as the outermost contour line of the end portion 91 in the captured image 12.

  However, as described above, if the conversion of the positional relationship between the position in the captured image 12 and the real space is based on the center height of the measurement object 90 as the reference height, the image is originally captured as the end portion 91. The region to be power is a point P on the center height of the end face 92.

  That is, as shown in FIG. 9, the lower edge 93 is detected as the outermost contour line at the position of the distance X from the camera axis 11 on the photographed image 12. It can be said that the position of the distance Xans should have been detected from the camera axis 11 which is the projection point.

  Therefore, if the position X of the outermost contour line in the photographed image 12 is corrected to be converted into the original position Xans, the accurate position of the end 91 can be obtained. Therefore, the ratio of the position Xans that should have been detected from the position X of the detected outermost contour line is examined.

  The vertex of the angle of view of the camera 10 is O, the point on the end surface 92 at the center height (reference height) 95 of the measured object 90 is P, and the camera axis 11 is also at the center height (reference height) 95. , A is the lower edge 93 of the end face detected as the outermost contour line, C is the intersection of the horizontal straight line 96 and the straight line OP at the height of the lower edge 93, and A point on the camera axis 11 is B, and a height dimension of the measurement object 90 is D.

Since the straight line 96 and the surface of the captured image 12 are parallel,
BC: BQ = X: Xans
Since the distance between the camera shaft 11 and the end face 92 is the same regardless of the height position,
AP = BC
Here, triangle OAP and triangle OBQ are similar,
OA: OB = AP: BQ
H: (H + D / 2) = X: Xans
Therefore,
Xans = (1 + D / 2H) · X (1)
It becomes.

  When the outermost contour line is seen in the region on the right side of the photographed image 12, the lower edge 93 of the end face 92 is detected as the outermost contour line. Therefore, the position X of the outermost contour line in the photographed image 12 is detected. Is converted and corrected to Xans by the calculation formula (1), and this Xans is converted into a distance from the camera axis 11 on the reference height 95, whereby the distance L indicating the position of the end in the real space can be calculated. .

  FIG. 10 illustrates a method for calculating the end position when the end 91 of the measurement target 90 is photographed in a positional relationship in which the camera shaft 11 is positioned inside the plane including the end surface 92 of the measurement target 90. It is explanatory drawing. In the figure, the captured image 12 of the camera 10 is represented below the measured object 90.

  In this example, the measured object 90 is in a position in which the end surface 92 of the measured object 90 is separated from the camera axis 11 by a distance L to the inside of the measured object 90. In this positional relationship, as described above, the upper edge 94 of the end surface 92 is photographed as the outermost contour line of the end portion 91 in the photographed image 12.

  However, as described above, if the conversion of the positional relationship between the position in the captured image 12 and the real space is based on the center height of the measurement object 90 as the reference height, the image is originally captured as the end portion 91. The region to be power is a point P on the center height of the end face 92.

  That is, as shown in FIG. 10, on the photographed image 12, the upper edge 94 is detected as the outermost contour line at a position of a distance X from the camera axis 11, but originally the point P onto the photographed image 12 is detected. It can be said that the position of the distance Xans should be detected from the camera axis 11 which is the projection point.

  Therefore, if the position X of the outermost contour line in the photographed image 12 is corrected to be converted into the original position Xans, the accurate position of the end 91 can be obtained. Therefore, the ratio of the position Xans that should have been detected from the position X of the detected outermost contour line is examined.

  The vertex of the angle of view of the camera 10 is O, the point on the end surface 92 at the center height (reference height) 95 of the measured object 90 is P, and the camera axis 11 is also at the center height (reference height) 95. Is the point A, C is the upper edge 94 of the end face detected as the outermost contour line, Q is the intersection of the horizontal straight line 97 and the straight line OP at the height position of the upper edge 94, and the camera axis on the straight line 97 A point on 11 is B, and a height dimension of the measurement object 90 is D.

Since the straight line 97 and the surface of the captured image 12 are parallel,
BC: BQ = X: Xans
Since the distance between the camera shaft 11 and the end face 92 is the same regardless of the height position,
AP = BC
Here, triangle OAP and triangle OBQ are similar,
OA: OB = AP: BQ
H: (HD / 2) = X: Xans
Therefore,
Xans = (1-D / 2H) · X (2)
It becomes.

  When the outermost contour line appears in the left region of the photographed image 12, the upper edge 94 of the end face 92 is detected as the outermost contour line. Therefore, the position X of the outermost contour line in the photographed image 12 is determined. The distance L indicating the position of the end portion in the real space can be calculated by converting and correcting to Xans by the calculation formula (2) and converting this Xans into the distance from the camera axis 11 on the reference height 95.

  Next, the function of the image processing apparatus 20 that calculates the end position by the above calculation method and further calculates the length dimension of the measurement object 90 will be described.

FIG. 11 is a functional block diagram of the image processing apparatus 20. As shown in the figure, the image processing apparatus 20, the contour detection unit 21, the end face shape evaluation unit 22, the height position determination means 23, the end position calculating means 24, provided with a dimension calculation hand stage 2 5 functional ing.

  The contour line detecting means 21 detects the outermost contour lines of the end portions 91 and 91 of the measured object 90 from the captured images 12 of the end portions 91 and 91 of the measured object 90 by the cameras 10 and 10. I do. As described above, since the measured object 90 is illuminated by the backlight from behind, the measured object 90 appears as a silhouette in the captured image 12, and the outermost contour line can be detected from the brightness difference. .

  The end face shape evaluation means 22 evaluates the shape of the end face depending on whether or not the detected curve shape of the outermost contour line is a curve shape corresponding to the position of the outermost contour line in the captured image 12. It is.

  The height position discriminating means 23 discriminates the height position of the end portion of the measured object 90 photographed as the outermost contour line according to the position of the detected outermost contour line in the photographed image 12. Is.

  As described above, when the end surface 92 parallel to the camera axis 11 is to be measured, whether or not the end surface 92 is visible depending on the positional relationship between the end surface 92 and the camera axis 11 and, as a result, the upper edge 94 as the outermost contour line. And which of the lower edges 93 is visible is different.

  Therefore, in this embodiment, the upper edge 94 and the lower edge 93 are set in advance as candidate parts that are parts that can be detected as the outermost contour line, and their reference height (the center of the object 90 to be measured) is set. Height information from (height) is set in advance.

  Further, regarding the upper edge 94 and the lower edge 93 which are candidate parts, the areas on the right half surface and the left half surface centered on the camera axis 11 as the areas in the captured image 12 when being photographed as the outermost contour line. Is set in advance.

  As a result, if the outermost contour line is detected from the photographed image 12, the upper edge 94 and the bottom edge are detected from whether the photographed image 12 is in the right half surface area or the left half surface area obtained by dividing the photographed image 12 into two. It is possible to easily and quickly determine which side edge 93 is visible, and obtain height information thereof.

The end position calculation unit 24 corrects the position of the outermost contour line in the captured image 12 according to the height position of the outermost contour line, thereby measuring the measurement object 90 photographed as the outermost contour line. The position of the end portion 91 in the direction intersecting the camera axis 11 direction is calculated.

  In this embodiment, as described above, since it is determined whether the portion detected as the outermost contour line is the upper edge 94 or the lower edge 93 of the end surface 92, the above correction formula ( According to 1) or (2), the position of the outermost contour line in the captured image 12 is corrected.

In this embodiment, for taking respective opposite ends 91, 91 of the object to be measured 90 by two cameras 10, 10, contour detection on than, the height position determination, and ends the position calculation The processing is performed for both end portions 91 and 91, respectively.

  The dimension calculation means 25 calculates the dimension of the measurement object 90 based on the calculated position of the end.

  In this embodiment, the dimension of the measured object 90 is calculated based on the positions of both end portions 91 and 91 of the measured object 90 measured from the captured images 12 of the two cameras 10 and 10 described above.

  Specifically, since these two cameras 10 and 10 are both ideal measurement objects 90, they are arranged at positions where the end portions 91 and 91 are captured at the center of the captured image 12. It is possible to calculate the length dimension of the measured object 90 to be measured by adding or subtracting the deviation amount from the ideal position of 91, 91 to the ideal length dimension of the measured object 90. it can.

  As described above, according to the end face shape inspection apparatus according to the present embodiment, it is determined whether or not the detected outermost contour curve shape is a curve shape according to the position in the captured image, that is, the imaging angle. . Therefore, even when the measured object has a height in the camera axis direction, and there is a possibility that a part with a different height position constituting the end depending on the imaging angle may be imaged, the shape of the end face is accurately Can be evaluated.

  In addition, it is possible to easily inspect based on an image captured by a normal camera having an angle of view.

  In addition, since the outermost contour line is used as a detection target, it can be detected with high reliability.

  Moreover, according to the end surface shape inspection apparatus concerning this embodiment, the position of an end surface and the length dimension of a to-be-measured body can be measured with an end surface shape inspection.

  And in this position measurement of the end face, in order to determine the height position of the end of the measurement object being photographed as the outermost contour line according to the position in the photographed image, and to correct according to the height position, Even when the object to be measured has a height in the camera axis direction and there is a possibility that parts with different height positions constituting the end depending on the imaging angle may be imaged, the position of the end is accurately measured can do.

  In particular, the length measurement according to the present embodiment can measure the position of the end of the measured object with high accuracy from an image taken by a camera having a general angle of view, and is an expensive three-dimensional shape. Functions equivalent to the measurement device can be realized at a lower cost.

  In addition, since a different correction calculation formula is used depending on the height position of the end, an appropriate correction calculation can be performed.

  Further, since the height information of the candidate part is set in advance, the height position of the end of the measured object that is imaged as the detected outermost contour line can be accurately determined.

  In addition, a region to be imaged as the outermost contour line is set in advance, and a measured object imaged as the detected outermost contour line is determined in order to determine a candidate region being imaged according to which region belongs to It is possible to quickly determine the height position of the end portion.

  Moreover, since the measurement is performed by irradiating the measurement object 90 with backlight illumination, the outermost contour line can be detected more accurately.

  In addition, since the length dimension of the measurement object 90 is calculated based on the positional relationship calculated by imaging both end portions 91 and 91 of the measurement object 90, the measurement object 90 is not dependent on the position of the measurement object 90 at the time of imaging. The dimension can be measured.

  In addition, since each end 91, 91 of the object to be measured is photographed by different cameras 10, 10 and the respective positions are calculated, each camera 10.10 uses each end 91, 91 of the object 90 to be imaged. The position of the camera can be fixed, and the camera position can be stabilized and accurate measurement can be performed.

  In addition, the length of the cylindrical body (photosensitive drum substrate) serving as the measurement target 90 can be accurately measured, which can contribute to the supply of a cylindrical body with the required dimensional accuracy, for example.

  As mentioned above, although this invention was demonstrated based on embodiment, this invention is not limited above, You may comprise as follows.

  (1) In the above-described embodiment, imaging is performed by irradiating backlight illumination from behind the object to be measured. However, imaging that can detect the outermost contour of the end of the object to be measured without using backlight illumination or the like. May be performed.

  (2) In the above embodiment, the length dimension is calculated after measuring the positions of both ends of the measured object. However, the length dimension is not calculated, and the positions of one or more ends of the measured object are measured. May be measured.

  (3) In the above embodiment, each position is measured by photographing both ends of the measured object with different cameras, but each end is photographed sequentially by moving one camera, and each position is calculated. By doing so, you may make it perform the dimension measurement of a to-be-measured body. Alternatively, the position of the object to be measured may be calculated by moving the object to be measured with respect to one camera and sequentially photographing each end. If it does in this way, the dimension of a to-be-measured object can be obtained from the position measurement result of a plurality of ends by one camera.

  (4) In the above-described embodiment, the two ends of the object to be measured are photographed with two cameras, each position is calculated, and the length dimension of the object to be measured is calculated. While contacting the position reference portion, another end face may be photographed to calculate its position, and the length dimension of the measured object may be calculated therefrom.

  Specifically, as shown in FIG. 12, for example, one (right side) end of the measurement object 90 is brought into contact with a predetermined position reference portion 40 that is predetermined in advance. In this state, as in the above-described embodiment, the other (left side) end is photographed by the camera 10 having the angle of view θ, and the position thereof is measured. And the dimension of a to-be-measured body is calculated based on the position of the said position reference | standard part, and the calculated position of the edge part.

  In this way, the dimension of the measured object 90 can be obtained from the position measurement result of the end by one camera 10. In addition, since the camera 10 can be fixed at a position where one end 91 of the measurement object 90 is included in the imaging range, the camera position can be stabilized and accurate measurement can be performed.

It is explanatory drawing of the end surface shape inspection apparatus which performs the inspection method of the end surface shape of the to-be-measured body concerning this invention. (A) is explanatory drawing which shows the case where the edge part of a to-be-measured object was image | photographed by the positional relationship to which a camera axis is located on the plane containing the end surface of a to-be-measured object, (b) is the imaging | photography image in that case It is an example. (A) is explanatory drawing which shows the case where the edge part of a to-be-measured object was image | photographed with the positional relationship to which a camera axis is located outside the plane containing the end surface of a to-be-measured object, (b) is a picked-up image in that case It is an example. (A) is explanatory drawing which shows the case where the edge part of a to-be-measured object was image | photographed with the positional relationship to which a camera axis is located inside the plane containing the end surface of a to-be-measured body, (b) is a picked-up image in that case It is an example. (A) is explanatory drawing which shows the case where the to-be-measured object of a flat end surface with narrow vertical width is image | photographed, FIG.5 (b) is an example of the picked-up image in that case. (A) is explanatory drawing which shows the case where the to-be-measured object of a flat end surface shape with a narrow width | variety is image | photographed, FIG.6 (b) is an example of the picked-up image in that case. (A) is explanatory drawing which shows the case where the to-be-measured object of end face shape which is not perpendicular | vertical with respect to a longitudinal direction is image | photographed with the attitude | position in which the end surface turned diagonally upward, FIG.7 (b) is a picked-up image of the case in that case. It is an example. (A) is explanatory drawing which shows the case where the to-be-measured object of the end surface shape which is not perpendicular | vertical with respect to a longitudinal direction is image | photographed with the attitude | position in which the end surface turned to the horizontal direction, FIG.8 (b) is the imaging | photography image in that case. It is an example. It is explanatory drawing explaining the calculation method of an edge part position when the edge part of a to-be-measured object is image | photographed by the positional relationship in which a camera axis is located outside the plane containing the end surface of a to-be-measured object. It is explanatory drawing explaining the calculation method of an edge part position when the edge part of a to-be-measured object is image | photographed by the positional relationship to which a camera axis is located inside the plane containing the end surface of a to-be-measured object. It is a functional block diagram of an image processing apparatus. It is explanatory drawing of the end surface shape test | inspection apparatus concerning other embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Camera 11 Camera shaft 12 Captured image 20 Image processing apparatus 30 Illumination apparatus 90 Measurement object 91 End part 92 End surface 93 Upper edge 94 Lower edge

Claims (11)

The end surface of the cylindrical or columnar object to be measured is photographed with a camera having an angle of view from a direction substantially parallel to the end surface,
Detect the outermost contour of the end face of the measured object from the captured image,
According to whether or not the detected curve shape of the outermost contour line is a curved shape according to the position of the outermost contour line in the captured image, the shape of the end face is evaluated .
As a curve shape according to the position, a curve shape when an outermost contour line of an ideal perfect circular shape is detected at a position in the captured image of the detected outermost contour line is calculated.
An end face shape inspection method for evaluating the shape of the end face of the measurement object by comparing the detected curve shape of the outermost outline with the curve shape of the outermost outline of the ideal end face. . An image of the curved shape of the detected most outer profile, by comparing the image of the curved shape of the outermost contour line of the ideal end faces, according to claim 1 for evaluating the shape of the end face of the object to be measured End face shape inspection method. By comparing a predetermined index value that is an index of the detected curve shape of the outermost contour line with the index value of the curve shape of the outermost contour line of the ideal end surface, the shape of the end surface of the measured object The end face shape inspection method according to claim 1 , wherein: Edge position measuring method according to any one of claims 1 to 3 for imaging by irradiating backlight illumination to the object to be measured. While evaluating the shape of the end face,
According to the position of the detected outermost contour line in the captured image, determine the height position of the part imaged as the outermost contour line,
By correcting the position of the outermost contour line in the captured image in accordance with the height position of the outermost contour line, the camera axis of the end face of the measurement object being photographed as the outermost contour line the end surface shape inspection method according to any one of claims 1 to 4 for calculating the position of the direction intersecting the direction. The end face shape inspection method according to claim 5 , wherein the length dimension of the measurement object is calculated based on the calculated position of the end face of the measurement object. Take a picture of both ends of the measured object,
While evaluating the shape of both end faces based on this captured image,
Calculate the position of both end faces based on this captured image,
The end face shape inspection method according to claim 6 , wherein the length dimension of the measurement object is calculated based on the calculated positional relationship between both end faces. The end face shape inspection method according to claim 7 , wherein each position is calculated by photographing both end faces of the measurement object with different cameras. The end surface shape inspection method according to any one of claims 1-8 object to be measured is a substrate for the photosensitive drum. An imaging means for imaging an end face of a cylindrical or columnar object to be measured from a direction substantially parallel to the end face with a camera having an angle of view;
Contour detection means for detecting the outermost contour of the end face of the object to be measured from the captured image;
End face shape evaluation means for evaluating the shape of the end face depending on whether or not the detected curve shape of the outermost contour line is a curved shape according to the position of the outermost contour line in the captured image ,
As a curve shape according to the position, a curve shape when an outermost contour line of an ideal perfect circular shape is detected at a position in the captured image of the detected outermost contour line is calculated.
An end face shape inspection apparatus that evaluates the shape of the end face of the measured object by comparing the detected curve shape of the outermost outline with the curve shape of the outermost outline of the ideal end face. . A height position determining means for determining a height position of a part imaged as the outermost contour line according to a position in the captured image of the detected outermost contour line;
By correcting the position of the outermost contour line in the captured image in accordance with the height position of the outermost contour line, the camera axis of the end face of the measurement object being photographed as the outermost contour line End position calculating means for calculating a position in a direction intersecting the direction;
The end surface shape inspection apparatus according to claim 10 , comprising:

Images