JP5822126B2 - Method and apparatus for inspecting liquid level of container - Google Patents

Description

  More particularly, the present invention relates to a liquid level inspection method and apparatus for inspecting the level of a liquid level in a container filled with liquid.

  Conventionally, for example, Patent Document 1 is known as a method for inspecting the liquid level in a container. In the inspection method of Patent Document 1, a container that is irradiated with inspection light is photographed by photographing means, and the height of the liquid level in the container is inspected based on the photographed image. And in the method of patent document 1, the case where the liquid level of the filling liquid in a container bubbles is assumed, In that case, it is between the upper height and lower part height of the liquid level area | region where the bubble has arisen. The height is inspected as the liquid level.

JP 2008-261696 A

  By the way, the following problems occur when the liquid level height of the container is inspected by the method of Patent Document 1. That is, when the cap with a pull ring is attached to the container, the liquid level in the container and the pull ring may be at the same height, and if the container in that state is photographed by the photographing means, the pull ring becomes an obstacle and the container The liquid level inside is not photographed (see FIG. 2). In this case, since the liquid level area cannot be recognized in the image of the container, it is impossible to inspect the liquid level based on the photographed image. Therefore, in this case, the filling liquid is correctly filled in the container. Nevertheless, it is determined as a defective product, and the container is excluded from the normal processing line. As described above, in the conventional method, a container erroneously determined as a defective product may be generated due to an accessory of the container such as a pull ring.

In view of the above-described circumstances, the first aspect of the present invention images a container filled with liquid, sets an inspection area in the image of the imaged container, and displays a liquid level area indicating the liquid level in the inspection area. By recognizing, in the method for inspecting the liquid level of the container, the liquid level in the container is inspected,
When the liquid level area cannot be recognized in the inspection area by being covered by the accessory included in the container, in the image of the container, a liquid detection area is set below the correct liquid level of the container, When the liquid level area is not recognized in the inspection area, it is determined that the liquid level is at a correct height by detecting the liquid in the liquid detection area. is there.
The second aspect of the present invention is a conveyor for transporting containers filled with liquid, illumination means for irradiating inspection light onto the containers transported by the conveyor, and imaging means for photographing the container irradiated with the inspection light. And an image processing means for processing an image of the container photographed by the photographing means, wherein the image processing means sets an inspection area in the image of the container and indicates a liquid surface area indicating a liquid surface in the inspection area. In the liquid level inspection device for a container that recognizes and inspects the liquid level in the container based on this,
The image processing means is configured to set a liquid detection area below the correct liquid level of the container in the image of the container, and the liquid level area is not recognized in the inspection area. Is characterized in that the liquid level is determined to be at the correct height by referring to the liquid detection area and detecting the liquid in the liquid detection area.

  According to the above-described configuration, for example, when inspecting the liquid level of a container having an accessory such as a cap with a pull ring, even if the liquid level in the container cannot be photographed by being covered with the accessory. The liquid level of the container can be inspected. Therefore, it can be prevented that the product is erroneously determined as a defective product.

BRIEF DESCRIPTION OF THE DRAWINGS Schematic explanatory drawing which shows one Example of this invention. The figure which shows the image of the container image | photographed with the imaging | photography means of FIG. The figure which shows the image of the container image | photographed with the imaging | photography means of FIG. The figure which shows the image of the container image | photographed with the imaging | photography means of FIG. The figure which shows the image of the container image | photographed with the imaging | photography means of FIG.

  Hereinafter, the present invention will be described with reference to the illustrated embodiment. In FIG. 1, reference numeral 1 denotes a liquid level inspection apparatus for inspecting the height of the liquid level in the container 2, and the liquid level inspection apparatus 1 The conveyor 3 for conveying, the illumination means 4 for irradiating the inspection light toward the container 2, the imaging means 5 such as a CCD camera for photographing the container 2 in the state irradiated with the inspection light, and controlling these operations Control means 6 for inspecting the height of the liquid level in the container 2 based on the image of the container 2 photographed by the photographing means 5 is provided.

The container 2 to be inspected is composed of a main body portion 11 that transmits inspection light and a cap 12 with a pull ring 12A attached to the upper end opening portion 11a of the main body portion 11. The liquid 13 that transmits the inspection light is filled. For this reason, the main body part 11 and the liquid 13 inside thereof transmit the inspection light emitted from the illuminating means 4.
The body portion 11 of the container 2 includes an upper end opening portion 11a to which the cap 12 is attached, a small diameter portion 11b that is an adjacent lower portion of the upper end opening portion 11a, a large diameter portion 11c on the lower side, and the small diameter portion 11b. A conical shoulder portion 11d that smoothly connects the large diameter portion 11c is provided.
On the other hand, the cap 12 of the present embodiment is a cap with an annular pull ring 12A, and the cap 12 with a pull ring 12A is attached to the upper end 11a of the mouth 2 of the container 2 filled with the liquid 13 in a previous process (not shown). It is like that. When the cap 12 is attached to the upper end opening portion 11a of the container 2, the annular pull ring 12A is in close contact with the outer surface of the small diameter portion 11b as shown in FIGS. In this embodiment, the pull ring 12A disposed on the outer surface of the container 2 corresponds to an accessory included in the container.

The conveyor 3 conveys adjacent containers 2 at equal intervals, and a pair of guide members 14 for guiding the left and right sides of the large-diameter portion 11c of the containers 2 above the placement surface of the conveyor 3. Is arranged. A sensor 15 for detecting the container 2 is disposed on the side of the conveyor 3 that is upstream of the illumination unit 4 and the photographing unit 5, and the conveyor 3 includes an encoder (not shown).
When the sensor 15 detects the container 2 conveyed by the conveyor 3, the detection signal is transmitted to the control means 6, and then the control means 6 recognizes the position of the container 2 by a pulse from the encoder, and the container 2 When a predetermined position A is reached, the photographing means 5 is controlled so that the container 2 is photographed.

The illumination means 4 of the present embodiment includes a first light source 4A composed of LEDs disposed on one side of the conveyor 3, and a second light source 4B composed of LEDs disposed on the other side of the conveyor 3. During the operation of the liquid level inspection apparatus 1, the inspection light is always irradiated from both the light sources 4A and 4B toward the container 2 at the imaging position A. The first light source 4A irradiates the inspection light horizontally toward the upper part of the container 2 including the cap 12, and the second light source 4B obliquely faces the pull ring 12A of the cap 12 that is the upper part of the container 2. Inspection light is irradiated from above.
On the other side of the same conveyor 3 as the second light source 4B, facing the first light source 4A across the container 2 to be transported, the photographing means 5 obliquely upward toward the upper part of the container 2 The inspection light emitted from the first light source 4A passes through the main body 11 of the container 2 and the liquid 13 inside and is received by the photographing means 5. The second light source 4B is irradiated with inspection light obliquely from above toward the pull ring 12A of the cap 12, and reflected light from the pull ring 12A is photographed by the photographing means 5. The imaging means 5 takes an image of the container 2 from the side in the transport direction under the control of the control means 6, and the images of the container 2 and the cap 12 taken by the imaging means 5 are provided in the control means 6. Is transmitted to the image processing means 6A.

The image processing means 6A is configured to set the inspection area SA in the image photographed by the photographing means 5. The inspection area SA is formed as a vertically long rectangular area as shown in FIG. 4, includes the correct height range of the liquid surface 13 </ b> A of the liquid 13, and is set to be approximately in the center of the width of the container 2. Is done.
The image photographed by the photographing means 5 is an image obtained by irradiating the photographing means 5 with the inspection light from the back of the container 2 by the first light source 4A. In the inspection area SA, the liquid 13 in the container 2 and its Images of the upper space 16 and the liquid level 13A between the liquid 13 and the space 16 are included. Since the interfacial tension between the gas in the space 16 and the inner surface of the container 2 is larger than the interfacial tension between the liquid 13 and the inner surface of the container 2, the liquid surface 13A is lifted at the edge portion in contact with the inner surface of the container 2. When 2 is photographed from the side, it is captured as an image having a vertical width.
In such an image, since the liquid 13 and the space 16 transmit the inspection light of the first light source 4A, the transmitted light is received by the imaging unit 5 and is photographed as a bright image. Is taken as a dark shadow image because the inspection light is difficult to transmit.

The image processing means 6A binarizes the image in the inspection area SA with a predetermined threshold value set in advance. Thereby, the liquid 13 and the space 16 of the bright image are converted into white pixels, and the liquid surface 13A of the dark shadow image is converted into black pixels. As a result, in the inspection area SA, only the liquid surface area showing the black belt-like liquid surface 13A crossing the vertically long inspection area SA remains.
The image processing means 6A scans each pixel in the inspection area SA up and down to recognize the upper side and the lower side of the black belt-like liquid surface area made up of a set of black pixels, and sets the middle position in the inspection area SA. It is recognized as a position in the vertical direction, and whether or not the value is included in the correct height range in the vertical direction of the inspection area SA is inspected. As a result, if it is included in the correct height range, it is determined that the liquid level 13A is at the correct height as a non-defective product. If the liquid level 13A cannot be confirmed within the correct liquid level height range, it is determined that the liquid 13 is not properly filled and is determined to be defective.

However, when the accessory of the container 2 such as the pull ring 12A is provided on the outer surface of the container 2 as in the present embodiment, the accessory may be attached to the photographing means 5 depending on the orientation of the container 2 being conveyed. In some cases, the liquid level cannot be correctly determined after being photographed.
That is, since the pull ring 12A does not transmit the inspection light of the first light source 4A, if the image is included in the inspection area SA, it cannot be distinguished from the original liquid level 13A.
Therefore, in this embodiment, the imaging unit 5 receives the reflected light from the pull ring 12A by irradiating the inspection light of the second light source 4B obliquely from above to the front of the container 2 to be imaged. I am doing so. As a result, the pull ring 12A is photographed as a bright image, and when the image processing means 6A performs binarization processing, it is converted into white pixels in the same manner as the liquid 13 and the space 16 to determine the liquid level height. Disappears.

In such an inspection method, there is no problem as long as the accessory of the container such as the pull ring 12A does not overlap the correct height range of the liquid surface 13A. As a result, the liquid level 13A cannot be correctly recognized because it is covered with the accessory, and the liquid level area having the correct height cannot be recognized in the inspection area SA.
That is, as shown in FIG. 2, when the container 2 is photographed from the side with the pull ring 12A positioned in the correct liquid level height range, the entire liquid level 13A is covered with the pull ring 12A. I can't get a statue. Even if this image is binarized in the inspection area SA by the image processing means 6A, the liquid level area composed of black pixels indicating the liquid level 13A cannot be recognized as a predetermined black band-like area. For this reason, the image processing means 6A determines that the container 2 is an empty container not filled with the liquid 13, and determines that the container is defective.
Therefore, in order to cope with such a situation, in the present invention, the liquid detection region A1 including the outline of the container 2 is set in the surface image photographed by the photographing means 5, and the liquid 13 in the container 2 is detected. I am doing so.

As shown in FIGS. 2 and 3, the liquid detection area A <b> 1 is disposed below the correct liquid level 13 </ b> A of the container 2 in the image of the container 2, and includes the contour of the container 2. In this embodiment, it is set as a square area. The liquid detection area A1 includes external light around the container 2 and an image of the container 2, and when the liquid surface area due to the black pixels of the liquid surface 13A cannot be recognized in the inspection area SA. The image of the liquid detection area A1 is binarized and referred to.
That is, when the container 2 is filled with the liquid 13 as shown in FIG. 2, the external light around the container 2 and the transmitted light transmitted through the container 2 are both photographed as bright images, and binarized. By processing, all the liquid detection areas A1 become white pixels. In this way, the liquid 13 can be detected in the liquid detection region A1 by using only white pixels. As a result, even if the liquid surface area cannot be recognized as the predetermined black belt-shaped area in the inspection area SA, it is determined that the liquid 13 is not filled and the defective area is not determined. It can be determined that the liquid surface is at a correct height as a non-defective product.
On the other hand, when the container 2 is not filled with the liquid 13, the outline 18 of the container 2 appears as a dark image as shown in FIG. 3, and a black line composed of black pixels when binarized. Is displayed. Therefore, when this black line is recognized, it is determined that the liquid 13 cannot be detected in the liquid detection region A1 and the container 2 is not filled with the liquid 13.
The method and means for detecting the presence / absence of the liquid 13 in the container 2 are not limited to this. For example, the large-diameter portion 11c in which the liquid 13 in the container 2 that does not include the contour line 18 is captured is photographed. The density of the container 2 is inspected, and when it is dark, it can be determined that the liquid 13 is present.

Further, when the appendage of the container 2 such as the pull ring 12A overlaps the correct height range of the liquid level 13A, when the liquid 13 is bubbling, the height direction of the liquid level region of the bubbling liquid level 13A Is larger than the width of the pull ring 12A, which is an accessory, so that the liquid level area is recognized in the inspection area SA in a vertically divided state, and the liquid level height cannot be correctly determined.
That is, as shown in FIG. 5, the liquid surface 13 </ b> A is captured as an image having a large width up and down due to the bubbling of the liquid 13, and the portion of the bubbling liquid image 13 </ b> A is difficult to transmit inspection light. Taken as.
Since the image processing means 6A binarizes the image in the inspection area SA with a predetermined threshold value set in advance, the bright image liquid 13 and the space 16 are converted into white pixels, and a dark shadow image foamed liquid. Surface 13A is converted to black pixels. As a result, in the inspection area SA, only the black belt-shaped liquid surface area that occupies most of the vertically long inspection area SA remains.
The image processing means 6A recognizes the intermediate position between the upper and lower sides of the liquid surface area as the vertical position in the inspection area SA, and the value is included in the correct vertical range of the inspection area SA. Inspect whether or not. As a result, if it is included in the correct height range, it is determined that the liquid level 13A is at the correct height as a non-defective product. If the liquid level 13A cannot be confirmed within the correct liquid level height range, it is determined that the liquid 13 is not properly filled and is determined to be defective.

  However, when the pull ring 12A overlaps with the foamed liquid surface 13A, the bright pull ring 12A is positioned within the foamed liquid surface 13A of the dark shadow image, and when this is binarized in the inspection area SA, The liquid surface area is divided into upper and lower parts by white pixels by the pull ring 12A and displayed as two black belt-like areas. In such a case, the image processing means 6A recognizes an intermediate position between the upper side and the lower side of the two liquid surface areas, and makes an erroneous determination.

  Therefore, when the image processing means 6A scans each pixel of the inspection area SA up and down and recognizes the upper side and the lower side of the black belt-like liquid surface area, the image processing unit 6A uses the group of white pixels formed by the image of the pull ring 12A. When the liquid surface area divided into two is recognized, the white pixel portion between the upper and lower liquid surface areas is converted into a black pixel to integrally recognize the liquid surface area, and then the inspection area SA again. Each pixel is scanned up and down. As a result, the upper and lower sides of the black belt-shaped liquid surface region composed of a set of black pixels are recognized, and the intermediate position is recognized as the vertical position in the inspection region SA, and the value of the recognized intermediate position is determined. It is inspected whether it is included in the correct height range in the vertical direction of the inspection area SA. As a result, if it is included in the correct height range, it is determined that the liquid level 13A is at the correct height, and it is determined as a non-defective product, and if it cannot be confirmed within the correct liquid level height range, it is determined as a defective product.

  In the embodiment described above, the cap 12 with the pull ring 12 </ b> A is assumed as an accessory of the container 2, but the liquid level inspection apparatus 1 of this embodiment attaches the accessory of the container 2 to the surface of the container 2. Even a label or a sticker attached can be dealt with, and even in that case, the same operation and effect as the above-described embodiment can be obtained.

DESCRIPTION OF SYMBOLS 1 ... Liquid level inspection apparatus 2 ... Container 4 ... Illuminating means 5 ... Imaging means 6 ... Control means 6A ... Image processing means 12 ... Cap 12A ... Pull ring (accessory)
13 Liquid 13A Liquid level SA Inspection area A1 Liquid detection area

Claims (4)

By photographing a container filled with liquid, setting an inspection area on the image of the photographed container, and recognizing the liquid level area indicating the liquid level in the inspection area, the liquid level in the container is increased. In the method for inspecting the liquid level of a container that is to inspect
When the liquid level area cannot be recognized in the inspection area by being covered by the accessory included in the container, in the image of the container, a liquid detection area is set below the correct liquid level of the container,
When the liquid level area is not recognized in the inspection area, it is determined that the liquid level is at a correct height by detecting the liquid in the liquid detection area. Liquid level inspection method. When the width of the liquid surface region in the height direction is larger than the width of the appendage, and the liquid surface and the appendage overlap each other and the liquid surface region is recognized by dividing up and down,
2. The method for inspecting a liquid level of a container according to claim 1, wherein a part between the upper and lower liquid level areas is included in the liquid level area so as to integrally recognize the liquid level area. Conveyor for transporting containers filled with liquid, illumination means for irradiating inspection light onto the containers transported by the conveyor, photographing means for photographing the container irradiated with inspection light, and the container photographed by the photographing means Image processing means for processing an image,
The image processing means sets an inspection region on the image of the container, recognizes a liquid surface region indicating a liquid surface in the inspection region, and inspects the height of the liquid surface in the container based on the recognition region. In the liquid level inspection device for the container
In the image of the container, the image processing means sets a liquid detection area below the correct liquid level of the container,
If the liquid level area is not recognized in the inspection area, the liquid detection area is referred to, and it is determined that the liquid level is at the correct height by detecting the liquid in the liquid detection area. An apparatus for inspecting the liquid level of a container, characterized in that: The illumination means includes a first light source disposed on one side of the conveyor and a second light source disposed on the other side,
The photographing means is disposed on the other side of the conveyor, which is the same as the second light source, facing the first light source with a container to be transported therebetween, and is irradiated with the first light source. The container is photographed from the side in the transport direction so as to receive the transmitted light that has been transmitted and the reflected light that is irradiated from the second light source and reflected by an accessory included in the container. Liquid level inspection device for containers.

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