JP2004294256A - Container outline inspection apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To highly accurately inspect the outlines of containers without being affected by position deviations etc. of the containers and to inspect large-size or wide-mouthed containers without having to use a lens of a large effective diameter. <P>SOLUTION: The container outline inspection apparatus includes a light projecting device 1 for projecting light toward the peripheral surface of a container 99'; a pair of optical systems 7A and 7B opposed to the light projecting device 1 correspondingly to both side parts of the container 99'; and imaging planes 8A and 8B each for forming an optical images of both side parts of the container 99' by the optical systems 7A and 7B. The optical systems 7A and 7B are each constituted of a telecentric optical system in which diaphragms 10A and 10B are located at focal positions on the rear side of lenses 9A and 9B. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
[Industrial applications]
The present invention relates to a container outer shape inspection device for optically inspecting a container such as a glass bottle, a plastic bottle, or the like in a non-contact manner, such as an outer shape of a body or a mouth. The present invention relates to a container outer shape inspection device which can be inspected for a container having a large opening and a container having a large opening.
[0002]
[Prior art]
Generally, when a container is manufactured, an inspection is performed in the inspection process to determine whether the outer shape of a mouth or a trunk is appropriate. For example, for the body of a container, it is checked whether the body diameter is larger or smaller than a specified value due to settling or elongation, or whether the outer shape of the body is a perfect circle. Conventionally, such an inspection has been performed by a contact-type body diameter inspection apparatus (for example, see Patent Document).
[0003]
[Patent Document]
Published Japanese Utility Model Application No. 58-63512
FIG. 10 shows a conventional body diameter inspection apparatus, in which the container 1 supported in the concave portion 51 of the star wheel 50 is transported to a predetermined inspection station by intermittent rotation of the star wheel 50, and then the outer peripheral surface of the container 1 The body diameter of the container 1 is measured at a predetermined height position while the container 1 is axially rotated by friction by bringing the rotating wheel 52 into contact. A roller 53 is pressed against the outer peripheral surface of the body of the container 1 at a predetermined height position by a spring 55, and the roller 53 rolls on the body of the container 1 with the rotation of the container 1. The roller 53 is rotatably supported at the distal end of a rod 54, and a photoelectric displacement sensor (not shown) is provided at the proximal end of the rod 54. Since the output of the displacement sensor fluctuates according to the reciprocating motion of the rod 54, the body diameter of the container 1 is determined from the output.
[0005]
[Problems to be solved by the invention]
In the above-mentioned body diameter inspection apparatus, since the roller 53 is pressed against and brought into contact with the outer peripheral surface of the container 1, if the container 1 is displaced or the roller 53 jumps during rolling, an error occurs in the output of the displacement sensor, Inspection accuracy deteriorates. Further, there is also a problem that the roller 53 is worn or rattled due to long-term use, and the accuracy of the inspection gradually decreases.
[0006]
To solve this problem, it is necessary to use an optical inspection device that inspects the outer shape of the container in a non-contact manner. Use of such an inspection device enables high-precision inspection without adverse effects such as displacement of the container and jumping phenomena of the rollers, and it is also possible to maintain the accuracy of the inspection over a long period of time. .
[0007]
FIG. 11 shows a typical example of an optical inspection apparatus. In the figure, reference numeral 101 denotes a light source that generates diffused light. An optical device 103 is disposed at a position facing the light source 101 with the container 99 interposed therebetween. The optical device 103 includes an optical system 105 in which a plurality of lenses and a stop arranged at an intermediate position are integrally mounted, and forms an optical image 107 of the container 99 on an image forming surface 106. In the drawing, a dotted line passing through the center of the optical system 105 is the optical axis 104 of the optical system 105. Further, a solid line reaching the image forming plane 106 through the optical system 105 is an optical path of a portion of the optical image 107 that looks bright.
[0008]
In the inspection apparatus having the above configuration, the position of the container 99, as shown by a chain line in the figure, when displaced along the optical axis 104, since the size of the optical image 107 varies from P ₁ to P _2, the container An error occurs in the measured value of the outer diameter of 99. In order to prevent the occurrence of this measurement error, it is necessary to increase the positioning accuracy of the container 99 so that the position of the container 99 does not shift. However, there is a limit in increasing such accuracy.
[0009]
The present invention has been made in view of the above problems, and has as its object to provide a container outer diameter inspection apparatus capable of inspecting the outer shape of a container with high accuracy without being affected by positional deviation of the container. .
[0010]
Another object of the present invention is to provide an inexpensive and small-sized container capable of inspecting a large container having a large body diameter or a wide-mouthed container having a large mouth diameter without using a lens having a large effective diameter. An object of the present invention is to provide a container shape inspection device.
[0011]
[Means for Solving the Problems]
The container outer shape inspection device according to the present invention includes a light emitting device that projects light toward the outer peripheral surface of the container, and a pair of optical systems that are provided so as to face the light emitting device corresponding to both side portions of the container. And image forming surfaces for forming optical images of both sides of the container by the respective optical systems. Each optical system is constituted by a telecentric optical system in which an aperture is located at a focal position on the rear side of the lens.
[0012]
Further, in addition to the above-described configuration, the container outer shape inspection apparatus according to the present invention performs image processing for capturing optical images of both sides of the container from an image forming plane and performing image processing for measuring the outer diameter of the container. It further comprises a device.
[0013]
In a preferred embodiment of the present invention, in order to obtain an optical image with good contrast that facilitates image processing, as the light projecting device, a light source for generating diffused light, and light from the light source are passed through and directed to a container. And an optical system for projecting the image, wherein the optical system is constituted by a telecentric optical system in which an aperture is located at a focal position on the front side of a lens. However, the optical system does not necessarily need to be a telecentric optical system, and if the image quality of an optical image is somewhat sacrificed, a light projecting device including, for example, only a light source that generates diffused light may be used. Good.
[0014]
The light projecting device may be a single light projecting device or a pair of light projecting devices arranged in parallel with each other so as to correspond to both sides of the container.
[0015]
In addition, it is desirable that each optical system can be moved so as to be able to approach or separate from each other in accordance with the size of the container to be inspected. It need not be a possible configuration.
[0016]
The container outer shape inspection apparatus according to the present invention, for example, inspects the outer shape of the body and mouth of the container.When inspecting the body, each optical system is provided on both sides of the body of the container. When the mouth is inspected correspondingly, each optical system is positioned corresponding to both sides of the mouth of the container.
[0017]
[Action]
After arranging a pair of optical systems so as to correspond to both sides of the body of a large container and facing the light projecting device, and projecting light toward the outer peripheral surface of the container by the light projecting device, each optical system The optical images of both sides of the body are formed on the image forming plane, and information relating to the outer shape of the body of the container can be obtained from each optical image.
Since each optical system is constituted by a telecentric optical system, only light parallel to the optical axis passes through the lens after being refracted, reaches the image forming plane through the aperture of the stop, and is not parallel to the optical axis. Even if the light refracts and passes through the lens, it is blocked without reaching the aperture of the stop. Therefore, even if the position of the container shifts, the size of the optical image does not change.
[0018]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 and FIG. 2 show the configuration of a container outer shape inspection apparatus according to an embodiment of the present invention.
The external shape inspection apparatus shown in the illustrated example can be inspected not only for a small container having a small body diameter and a container having a small opening but not for a wide opening, but also for a large or wide opening container 99 ′. The basic principle is the same as that of the external shape inspection apparatus shown in FIG. 3 in which the container and the non-wide-mouthed container 99 are exclusively inspected. Therefore, the configuration of the embodiment shown in FIGS. 1 and 2 will be referred to here while explaining the principle by the outer shape inspection apparatus of FIG. In the following specific example, the case where the body of the container is inspected is assumed, but the invention is not limited thereto, and the mouth of the container may be inspected.
[0019]
The contour inspection apparatus shown in FIG. 3 is a light projecting device 1 that projects light to the outer peripheral surface of a container 99, and a light source 2 that generates diffused light, and an optical device that irradiates the body of the container 99 with light from the light source 2. System (hereinafter, referred to as “first optical system”) 3. An optical device 6 including another optical system (hereinafter, referred to as “second optical system”) 7 is arranged on an optical axis 11 passing through the center of the container 99. An optical image 12 is formed on an image forming plane 8 composed of a CCD.
[0020]
Each of the first and second optical systems 3 and 7 is constituted by a telecentric optical system. As described above, since the first optical system 3 is configured by the telecentric optical system, the size of the optical image 12 does not change even if the position of the container 99 is shifted in the direction along the optical axis 11. Further, since the second optical system 7 is constituted by a telecentric optical system, the contrast of the optical image 12 is enhanced.
In the embodiment of the present invention shown in FIGS. 1 and 2, both sides of the body of the container 99 'are observed by a pair of optical devices 6A and 6B. The optical axes 11A and 11B of the second optical systems 7A and 7B are parallel to the center line 100 of the container 99a and are separated by a distance corresponding to the body diameter D of the container 99.
[0021]
Each of the first and second optical systems 3 and 7 has a lens mount (hereinafter simply referred to as a “lens”) 4, 9 which is a group of a plurality of lenses on the optical axis 11 and which can be adjusted in focus. In the first optical system 3, the aperture 5a of the aperture 5 is located at the focal position in front of the lens 4, and in the second optical system 7, the aperture 10a of the aperture 10 is located They are arranged so as to be located at the rear focal position.
[0022]
According to the first optical system 3, of the light from the light source 2, the light passing through the opening 5 a of the stop 5 is parallel to the optical axis 11. According to the second optical system 7, only light parallel to the optical axis 11 is refracted by the lens 9 and passes therethrough, and then is condensed on the image plane 8 through the opening 10 a of the stop 10. Therefore, even if light that is not parallel to the optical axis 11 passes through the lens 9 while being refracted, the light does not reach the opening 10 a of the diaphragm 10 and is blocked.
In FIG. 3, the optical path of the brightly visible portion of the optical image 12 formed on the image plane 8 is shown by a solid line, and the virtual optical path of the darkly visible portion (actually, no light passes) is shown by a dotted line. is there.
[0023]
The lens 9 of the second optical system 7 is focused on a portion P where the outer peripheral portion of the body projects most, that is, a portion corresponding to the diameter of the container 99 orthogonal to the optical axis 11. An optical image 12 from which information relating to the outer shape of can be obtained is obtained.
[0024]
In the second optical system 7, the principal ray parallel to the optical axis 11 involved in the formation of the optical image 12 is actually maximum α in the outer peripheral direction around the principal ray L (indicated by a solid line in the figure). (Indicated by a dashed line in the figure). This is because the aperture 10a of the stop 10 of the second optical system 7 is set to a correspondingly large diameter in order to secure a light amount necessary for measurement.
Similarly, in the first optical system 3, the principal ray parallel to the optical axis 11 also has a light component having a maximum opening angle α ′ in the outer peripheral direction around the principal ray L ′ (indicated by a dashed line in the figure). )have. This is because the aperture 5a of the stop 5 of the first optical system 3 is set to a correspondingly large diameter in order to secure a light amount necessary for measurement.
[0025]
FIG. 5 shows an optical image 12 formed on the image plane 8 of the optical device 6 of FIG. The optical image 12 includes a central bright portion 14 generated by light passing through the center of the body of the container 99 and dark portions 15 on both sides of the bright portion 14. The dark part 15 is a part that appears mainly when light is blocked by an inner thick part of the body part. However, if the diameter of the opening 5a of the stop 5 of the first optical system 3 is reduced, the width of the dark part 15 is increased and the background is enlarged. The contrast with the bright portion 16 is increased. The bright portion 16 is an image of the light source 2 behind the container 99 limited by the maximum field of view of the lens 9.
The distance d between the outer edges of the dark portions 15 on both sides is equivalent to the trunk diameter D of the container 99. If the distance d is within a predetermined threshold range, the container 99 of the optical image 12 becomes " If it is determined that the container 99 is non-defective, and if it is out of the range of the threshold, the container 99 of the optical image 12 is determined to be “defective”.
[0026]
Since the second optical system 7 on the image forming side is constituted by a telecentric optical system, the size of the optical image 12 does not change even if the position of the container 99 is shifted along the optical axis 11. In addition, since the first optical system 3 on the light projecting side is formed of a telecentric optical system, the contrast between the dark portion 15 and the bright portion 16 in the optical image 12 is increased, so that the image processing of the optical image 12 can be easily performed. Become.
[0027]
In the outer shape inspection apparatus according to the embodiment of the present invention shown in FIGS. 1 and 2, the optical images 12A and 12B of both sides of the body of the container 99 'are formed on the image forming surfaces 8A and 8B by a pair of optical devices 6A and 6B. After forming the images and combining the optical images 12A and 12B by image processing, the combined image is used to inspect the body diameter and the outer shape of the body.
[0028]
The outer shape inspection apparatus in the illustrated example uses a pair of optical devices 6A and 6B instead of the single optical device 6 in FIG. 3 in order to inspect a large or wide-mouthed container 99 '. This external shape inspection apparatus includes a single light emitting device 1, a pair of optical devices 6A and 6B, and an image processing device 20 having a display 19. The light projecting device 1 includes a light source 2 for generating diffused light and a first optical system 3 including a telecentric optical system. The first optical system 3 includes a lens 4 and a stop 5, and the stop 5 is positioned so that an opening 5 a thereof is located at a focal position on the front side of the lens 4.
[0029]
The container 99 'to be inspected is introduced onto the turntable 30 by a carry-in / out mechanism (not shown) and inspected. Then, after the inspection is completed, it is taken out from the turntable 30 by the carrying-in / out mechanism. When performing the inspection, the rotary table 30 is intermittently rotated by a predetermined angle and is connected to a rotation mechanism (not shown).
[0030]
Each of the optical devices 6A and 6B is movable so as to be able to approach or separate from each other. The optical devices 6A and 6B are opposed to the light projecting device 1 corresponding to both sides of the body of the container 99 ', and have respective optical axes. Second optical systems 7A and 7B positioned so that 11A and 11B are parallel to each other, and optical images 12A and 12B of both sides of the body of container 99 'are formed by second optical systems 7A and 7B. Imaging planes 8A and 8B. Each of the imaging planes 8A and 8B is constituted by a CCD. The optical images 12A and 12B formed by the second optical systems 7A and 7B formed on the image forming surfaces 8A and 8B are taken into the image processing device 20 and subjected to image processing for measuring the body diameter.
[0031]
Each of the second optical systems 7A and 7B includes lenses 9A and 9B and apertures 10A and 10B that constitute a telecentric optical system, respectively. Each of the lenses 9A, 9B has its respective optical axis 11A, 11B parallel to the centerline 100 of the container 99 'and spaced equidistant from its midline 100. The lenses 9A and 9B are located on the optical axes 11A and 11B, respectively, and the apertures 10A and 10B are positioned at the focal positions on the rear side of the lenses 9A and 9B, and further, the image plane 8A is located behind the apertures 10A and 10B. , 8B are positioned.
[0032]
Each of the lenses 9A and 9B is an aggregate of a plurality of lenses, and the focus can be adjusted. The focus of each lens 9A, 9B is adjusted to the portion P where the outer peripheral surface of the body of the container 99 'protrudes most.
Each of the apertures 10A and 10B has apertures 10a and 10b at the center, and the aperture area is changed by adjusting the aperture value to adjust the amount of light impinging on each of the imaging surfaces 8A and 8B. The aperture value is set to an optimum value that can obtain a certain depth of focus and sufficiently secure the light amount necessary for measurement.
[0033]
In Figure 2, the second optical system 7A, an optical image 12A in 7B, the principal ray _L A involved in imaging of 12B, _{L B} is a solid line, the opening angle of up to α each principal ray _L A, the _{L B} around The respective light components are indicated by alternate long and short dash lines. Further, the optical axis 11A in the first optical system 3, is parallel to the 11B principal ray _L A ', _{L B'} is in solid lines, the opening angle of the maximum alpha 'each principal ray _L A', _{L B} 'to the center The respective light components are indicated by alternate long and short dash lines.
[0034]
In the above embodiment, the light projecting device 1 is composed of the light source 2 and the first optical system 3 composed of a telecentric optical system. However, if the image quality of the optical images 12A and 12B is slightly sacrificed, As shown in FIG. 4, the light emitting device 1 may be configured with only the light source 2. In this case, instead of one light source 2, two light sources 2A and 2B (indicated by dashed lines in the figure) corresponding to both side portions of the container 99 can be configured.
In the above embodiment, one light emitting device 1 is used. Instead, two light emitting devices (not shown) corresponding to both sides of the container 99 are configured. You may.
[0035]
FIGS. 6A and 6B show optical images 12A and 12B of both sides of the body of the container 99 'formed on the image forming surfaces 8A and 8B. Each of the optical images 12A and 12B is a partial image of the trunk at a predetermined height. However, similarly to the optical image 12 described with reference to FIG. 5, the width of the dark portion 15 is widened and the contrast with the light portion 16 on the background is enhanced. Thus, the edge of the dark portion 15 is clear.
[0036]
The image processing apparatus 20 shown in FIG. 1 captures the optical images 12A and 12B from the respective image forming surfaces 8A and 8B and executes predetermined image processing for measuring the body diameter of the container 99 '. As shown in the figure, it is composed of a pair of image input units 21A and 21B, a pair of image memories 22A and 22B, an image output unit 23, a control unit 24, and the like.
Each of the image input units 21A and 21B takes in the grayscale image signals of the optical images 12A and 12B, converts them into digital grayscale image data, and further binarizes the binary image with a predetermined binarization threshold value. Generate Each of the image memories 22A and 22B is for storing grayscale image data and its binary image data. The image output unit 23 converts the image data into analog image data, outputs the analog image data to the display 19, and displays the image on the screen.
[0037]
The control unit 24 combines the binary images of the optical images 12A and 12B to generate a composite image 12C as shown in FIG. 8, and then calculates the body diameter D of the container 99 using the composite image 12C. First, the control unit 24 determines the distance between the edges (number of pixels) x1 of the two optical images 12A and 12B by the number of pixels x3 from one edge of the image to the edge of one optical image 12B and the other from the edge. From the number of pixels x2 up to the edge of the optical image 12A (x1 = x3-x2). Next, the number of pixels R corresponding to the body diameter D is obtained by adding a coupling error Δx caused by image coupling to the distance between edges x1 (R = x1 + Δx). Next, the body diameter D is calculated by dividing the number of pixels R by the conversion ratio β between the number of pixels and the actual size (D = R / β).
[0038]
The conversion factor β can be obtained by generating an optical image 12S (shown in FIG. 9) of the reference object using one optical device (for example, 6A) in the external shape inspection device in FIG.
For example, one optical device 6A is positioned so that the optical axis 11A coincides with the center line of the reference object, and for the optical image 12S obtained by the optical device 6A, the distance between edges (number of pixels) S1 is determined. After calculating from the difference (S1 = S3-S2) between the number of pixels S3 from one edge to the edge of one optical image 12S and the number of pixels S2 from the edge to the edge of the other optical image 12S, the edge The conversion ratio β is calculated by dividing the distance S1 by the actual size s of the reference object (β = S1 / s).
[0039]
Further, the coupling error Δx is obtained by generating an optical image 12E (shown in FIG. 8) of a large container as a reference object using both optical devices 6A and 6B in the outer shape inspection device of FIG. Can be.
That is, the binary images of the optical images 12A and 12B by the optical devices 6A and 6B are combined to generate a composite image 12E, and for the composite image 12E, first, the distance between the edges of the two optical images 12A and 12B ( The number of pixels (E1) is defined as the difference (E1 = E3−E3) between the number of pixels E3 from one edge of the image to the edge of one optical image 12B and the number of pixels E2 from the edge to the edge of the other optical image 12A. E2), the actual size e of the reference object is multiplied by the conversion value β to obtain a conversion value E obtained by converting the actual size e to the number of pixels. From the difference between the distance E1 between edges and the conversion value E, The coupling error Δx is calculated (Δx = E1−E).
[0040]
When the large container 99 'to be inspected is introduced on the turntable 30, the turntable 30 is rotated intermittently by a predetermined angle to generate optical images 12A and 12B of both sides of the body, The body diameter D is calculated by the set number by the above-described image processing. The control unit 24 calculates a maximum value, a minimum value, and a deviation between the maximum value and the minimum value from the set number of calculated values of the body diameter D, and the maximum value is a threshold value of the maximum value, and the minimum value is a minimum value. The threshold value of the value and the deviation are compared with the threshold value of the deviation, respectively, and if none of them exceeds the threshold value, it is determined to be “good”. However, if any of them exceeds the threshold value, a "defective" judgment is made.
[0041]
The above-described pass / fail determination is performed by calculating the body diameter D by a set number and comparing the maximum value, the minimum value, and the deviation of the calculated values with the respective threshold values, as in this embodiment. Alternatively, the number of pixels R corresponding to the body diameter D may be calculated by the set number without converting the number of pixels into the actual dimensions, and the maximum value, the minimum value, and the deviation of the calculated value may be determined by the respective thresholds. It may be performed by comparing with a value (the number of pixels).
[0042]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to this invention, the external shape of a container can be inspected with high precision, without being affected by the displacement of a container. In addition, a large-sized or wide-mouthed container can be inspected without using an expensive lens having a large effective diameter, and there is no danger of increasing the size and cost of the apparatus.
[Brief description of the drawings]
FIG. 1 is a front view showing the configuration of a container outer shape inspection apparatus according to an embodiment of the present invention.
FIG. 2 is an explanatory diagram showing a configuration and an optical path of an optical device.
FIG. 3 is a diagram illustrating the principle of the present invention.
FIG. 4 is a front view of another embodiment.
FIG. 5 is an explanatory diagram showing an optical image of a trunk.
FIG. 6 is an explanatory diagram showing optical images of both sides of a body by a pair of optical devices.
FIG. 7 is a block diagram illustrating a configuration of an image processing apparatus.
FIG. 8 is an explanatory diagram showing a composite image obtained by combining two optical images.
FIG. 9 is an explanatory diagram showing an optical image of a reference object.
FIG. 10 is a plan view showing a configuration of a conventional contact type outer shape inspection apparatus.
FIG. 11 is an explanatory diagram showing a configuration of a typical example of an optical inspection apparatus and an optical path.
[Explanation of symbols]
Reference Signs List 1 light projecting device 2 light source 3 first optical system 4 lens 5 diaphragm 6A, 6B optical device 7A, 7B second optical system 8A, 8B imaging surface 9A, 9B lens 10A, 10B diaphragm 11A, 11B optical axis 20 image processing device 99,99 'container

Claims (7)

A light projecting device for projecting light toward the outer peripheral surface of the container, a pair of optical systems arranged to face the light projecting device corresponding to both side portions of the container, and And a focusing surface for forming an optical image, wherein each optical system is constituted by a telecentric optical system in which a stop is positioned at a focal position on the rear side of the lens. The light projection device includes a light source that generates diffused light, and an optical system that transmits light from the light source and projects the light toward a container, wherein the optical system positions a stop at a focal position on a front side of a lens. The container outer shape inspection apparatus according to claim 1, wherein the apparatus is configured by a telecentric optical system. The outer shape inspection device for a container according to claim 1, wherein the light projecting device is a pair of light projecting devices arranged in parallel with each other corresponding to both side portions of the container. The container outer shape inspection apparatus according to claim 1, wherein each optical system is movable so as to be able to approach or separate from each other. The container outer shape inspection device according to claim 1, wherein each optical system is positioned so as to correspond to both side portions of the body of the container. The container outer shape inspection device according to claim 1, wherein each optical system is positioned so as to correspond to both side portions of a mouth of the container. The container shape inspection apparatus according to any one of claims 1 to 6, wherein an optical image of both sides of the container is captured from an image forming plane, and image processing for measuring an outer diameter of the container is performed. A container mouth inspection device further comprising an image processing device.

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