Container inspection method and inspection apparatus

Abstract

To provide an inspection method of a container suitable for detecting liquid adhesion on the outer surface of the container.SOLUTION: In an inspection method including the steps of: illuminating an inspection range of a container with excitation light in a wavelength range in which the container emits fluorescence and detecting liquid adhesion in the inspection range on the basis of the contrast difference of the fluorescence in the inspection range illuminated by the excitation light, the wavelength range of the excitation light is set to the wavelength range in which the intensity of the fluorescence in the liquid is relatively lower than the intensity of the fluorescence generated in the container, and the transmission of the excitation light in the liquid is restricted so that the contrast difference that should occur between the container and the liquid adhering to the container does not disappear.SELECTED DRAWING: Figure 8

Description

Technical Field

[0004] , ,

[0005] , , ,

[0001] The present invention relates to a method and an apparatus for inspecting a container for detecting adhesion of a liquid on an outer surface of the container.

Background Art

[0002] <00000(...)​​​​​​​​​​​​​​​​​​​​​​​​​​​Therefore, the present invention aims to provide a container inspection method suitable for detecting the adhesion of liquid to the outer surface of a container. [Means for solving the problem]

[0006] A method for inspecting a container according to one aspect of the present invention is a method for inspecting a container for detecting the adhesion of liquid to the outer surface of a container, comprising the steps of: illuminating an inspection area of ​​the container with excitation light in a wavelength range in which the container emits fluorescence; and detecting the adhesion of the liquid in the inspection area based on the difference in brightness of the fluorescence in the inspection area illuminated by the excitation light, wherein the wavelength range of the excitation light is set to a wavelength range in which the transmission of the excitation light to the liquid is limited such that the intensity of fluorescence in the liquid is relatively lower than the intensity of fluorescence produced in the container, and the difference in brightness that should occur between the container and the liquid adhering to the container disappears.

[0007] An inspection device for a container according to one aspect of the present invention is an inspection device for a container for detecting the adhesion of liquid to the outer surface of a container, comprising: an illumination means for illuminating an inspection area of ​​the container with excitation light in the wavelength range in which the container emits fluorescence; an imaging means for capturing an image that reflects the difference in brightness of fluorescence in the inspection area illuminated by the excitation light; and a detection means for detecting the adhesion of the liquid in the inspection area based on the difference in brightness of fluorescence in the image, wherein the wavelength range of the excitation light from the illumination means is set to a wavelength range in which the intensity of fluorescence in the liquid is relatively lower than the intensity of fluorescence generated in the container, and the transmission of the liquid is limited to a range in which the difference in brightness that should occur between the container and the liquid adhering to the container does not disappear. [Brief explanation of the drawing]

[0008] [Figure 1A] A figure showing an example of the results of measuring the three-dimensional fluorescence spectrum of rapeseed oil. [Figure 1B] This figure shows an example of the results of measuring the three-dimensional fluorescence spectra of other rapeseed oils with different additive components. [Figure 1C]This figure shows an example of the results of measuring the three-dimensional fluorescence spectrum of soybean oil. [Figure 1D] This figure shows an example of the results of measuring the three-dimensional fluorescence spectrum of rice bran oil. [Figure 1E] A figure showing an example of the results of measuring the three-dimensional fluorescence spectrum of safflower oil. [Figure 1F] A figure showing an example of the results of measuring the three-dimensional fluorescence spectrum of sesame oil. [Figure 1G] A figure showing an example of the results of measuring the three-dimensional fluorescence spectrum of olive oil. [Figure 2] This figure shows an example of the results of measuring the three-dimensional fluorescence spectrum of a resin container. [Figure 3] A diagram showing an example of the results of measuring the light transmittance of edible oil. [Figure 4] A diagram showing one form of container inspection device. [Figure 5] A diagram showing another form of container inspection device. [Figure 6] A diagram showing a further form of the container inspection device. [Figure 7] Figure 6 shows a side view of the inspection device. [Figure 8] A figure showing an example of an image obtained in Test Example 1. [Figure 9] A figure showing an example of further images obtained in Test Example 1. [Figure 10] A figure showing an example of an image obtained in Test Example 2. [Figure 11] A figure showing an example of an image obtained in a comparative example. [Modes for carrying out the invention]

[0009] An embodiment of the present invention will be described below with reference to the attached drawings. In this embodiment of the inspection method, excitation light of a specific wavelength range is irradiated onto the inspection area of ​​the container, and the adhesion of liquid to the outer surface of the container is detected based on the difference in brightness of the fluorescence produced in the inspection area in response to the irradiation. The wavelength range of the excitation light is selected according to the material of the container and the type of liquid whose adhesion to the outer surface of the container should be detected. Below, the wavelength range of the excitation light will be explained using the case where the container is made of resin and the liquid is edible oil to be filled into the container as the contents as an example.

[0010] Figures 1A to 1G show the results of measuring the three-dimensional fluorescence spectra of seven types of edible oils selected as samples, representing the relationship between the excitation light irradiated onto each sample and the fluorescence produced in response to that irradiation. In each figure, the vertical axis represents the wavelength range of the excitation light, and the horizontal axis represents the wavelength range of the fluorescence. The edible oils used as samples are rapeseed oil A (Figure 1A), rapeseed oil B (Figure 1B), soybean oil (Figure 1C), rice bran oil (Figure 1D), safflower oil (Figure 1E), sesame oil (Figure 1F), and olive oil (Figure 1G). Rapeseed oil A and rapeseed oil B are similar in that they are both made from rapeseed, but their added components differ.

[0011] As shown in Figures 1A to 1G, although there are differences in fluorescence characteristics depending on the type of edible oil, in all cases fluorescence occurs in the excitation light wavelength range of approximately 260 nm to 400 nm. In the examples in Figures 1A to 1E, the fluorescence wavelength range is approximately 400 nm, but in the sesame oil example in Figure 1F and the olive oil example in Figure 1G, fluorescence occurs in the wavelength range of approximately 320 nm. On the other hand, all examples share the common characteristic that the fluorescence intensity decreases in the excitation light wavelength range of approximately 280 nm or less, and fluorescence is almost absent in the wavelength range from around 260 nm onwards.

[0012] Figure 2 shows the results of measuring the three-dimensional fluorescence spectrum of a container made of polyethylene terephthalate resin (hereinafter referred to as PET resin). The vertical axis represents the wavelength range of the excitation light, and the horizontal axis represents the wavelength range of the fluorescence. According to Figure 2, in the case of a container made of PET resin, when the excitation light is in the wavelength range of approximately 200 nm to 400 nm, fluorescence in the wavelength range of approximately 360 nm to 420 nm occurs. The wavelength range of the excitation light that causes fluorescence in the container extends to the shorter wavelength side compared to the wavelength range of the excitation light that causes fluorescence in edible oil. Such characteristics are the same for containers made of resins different from PET resin.

[0013] Next, Figure 3 shows the results of examining the light transmission spectra of each sample of the edible oil used in Figures 1A to 1G. Also in Figure 3, the vertical axis represents the light transmittance, and the horizontal axis represents the wavelength range of the light. As is clear from Figure 3, in the case of edible oil, the light transmittance clearly decreases in the region on the shorter wavelength side with a wavelength of approximately 320 nm to 400 nm as the boundary. Focusing on the wavelength range around 280 nm, the transmittances of soybean oil, rice bran oil, safflower oil, and sesame oil are almost 0%, the transmittances of rapeseed oils A and B are approximately 10% or less, and even for olive oil, which has the highest transmittance, the transmittance decreases to around 45%. Regarding olive oil, its transmittance starts to decrease from the wavelength range around 320 nm, maintains a transmittance of approximately 45% in the wavelength range of approximately 270 nm to 280 nm, but the transmittance decreases again on the shorter wavelength side and becomes almost 0% at around 250 nm.

[0014] Considering the three-dimensional fluorescence spectrum and transmission spectrum as described above, in order to detect the adhesion of edible oil to the outer surface of the container, the wavelength range of the excitation light may be set as follows. First, the wavelength range in which the container can fluoresce is wider on the short wavelength side compared to the wavelength range in which edible oil can fluoresce. Focusing on this property, the wavelength range of the excitation light is set so that the container can fluoresce and the fluorescence intensity in the edible oil is relatively lower than the fluorescence intensity generated in the container. That is, when the first requirement is that it is a wavelength range in which the container can fluoresce and the second requirement is that it is a wavelength range in which the fluorescence intensity in the edible oil is relatively lower than the fluorescence intensity generated in the container, the wavelength range of the excitation light is set to satisfy both the first requirement and the second requirement. Thereby, while causing the container to fluoresce, the fluorescence emission of the edible oil adhering to the outer surface of the container can be suppressed compared to that of the container, and it is possible to create a contrast in fluorescence between the container and the edible oil. The greater the contrast between the container and the edible oil, the more advantageous it is for detecting the adhesion of the edible oil. Therefore, the wavelength range of the excitation light is preferably a wavelength range in which the edible oil does not fluoresce or, even if it fluoresces, its intensity clearly decreases compared to the fluorescence intensity generated in the container.

[0015] On the other hand, even if the fluorescence in the edible oil is suppressed, if the excitation light passes through the edible oil adhering to the outer surface of the container, the excitation light reaches the container behind the edible oil and fluorescence is generated, and the fluorescence passes through the edible oil and is emitted to the outside. In this case, the fluorescence generated behind the edible oil is observed from the outside, and as a result, the contrast between the container and the edible oil may be impaired and it may become difficult to distinguish between the two. In order to avoid such inconvenience, it is necessary to select excitation light in a wavelength range that acts as a means for restricting the transmission of the excitation light by the edible oil itself. Specifically, excitation light in a wavelength range in which the transmission of the excitation light in the edible oil is restricted may be selected so that the contrast that should occur between the container and the edible oil does not disappear. Hereinafter, the third requirement is that it is a wavelength range in which such a restricting effect occurs. Note that the disappearance of the contrast here is a concept that includes not only the case where the contrast is completely lost but also the case where the contrast decreases to an unrecognizable level.

[0016] If the wavelength range of the excitation light satisfies the first, second, and third requirements, a difference in brightness can be created between the container and the edible oil adhering to its outer surface, and this difference in brightness can be used as a clue to detect the presence of edible oil on the outer surface of the container. In order to create a difference in brightness between the container and the edible oil, it is advantageous to have a low transmittance of the edible oil in the selected wavelength range. However, the transmittance of the excitation light in the edible oil does not need to be exactly 0%. For example, if the transmittance of the edible oil in the wavelength range of the excitation light is at least 50% or less, preferably 30% or less, it may be possible to suppress the influence of the fluorescence emission of the container behind the edible oil on the difference in brightness between the container and the edible oil.

[0017] Next, we will examine the wavelength ranges that satisfy the first, second, and third requirements mentioned above, using the examples in Figures 1A to 1G and Figure 2. According to the example in Figure 2, it can be confirmed that resin containers fluoresce when the excitation light is in the wavelength range of approximately 200 nm to 400 nm. Therefore, the first requirement is satisfied if the excitation light wavelength range is set to 400 nm or less. On the other hand, according to the three-dimensional fluorescence spectra in Figures 1A to 1G, edible oil hardly fluoresces when the excitation light wavelength range is 260 nm or less. However, if the excitation light wavelength range is 280 nm or less, the fluorescence intensity is relatively low, and it is understood that the fluorescence emission of the edible oil can be suppressed to the extent that a difference in brightness between the container and the edible oil can be maintained. Therefore, in order for the excitation light wavelength range to satisfy the second requirement, it is sufficient to set the excitation light wavelength range to 280 nm or less as a guideline. Next, according to the light transmission spectrum in Figure 3, the transmittance of edible oil decreases to 50% or less regardless of type if the wavelength is 280 nm or less, and decreases to 30% or less if the wavelength is 260 nm or less. Therefore, it is considered that the third requirement is met regardless of the type of edible oil if the excitation light wavelength range is at least 280 nm or less, preferably 260 nm or less. In summary, to satisfy all of the first, second, and third requirements, the excitation light wavelength range should be set to 280 nm or less, preferably 260 nm or less. Such a wavelength range is included in the ultraviolet light wavelength range.

[0018] The lower limit of the excitation light wavelength range can be set as appropriate, as long as the first requirement is met. As shown in Figure 2, fluorescence occurs in the resin container at wavelengths of 200 nm or higher. Since the wavelength range below 200 nm is called vacuum ultraviolet, for practical purposes, 200 nm can be used as a guideline for the lower limit of the excitation light wavelength range. Light sources in the ultraviolet range that are relatively easy to obtain on the market are 222 nm, 265 nm, and 280 nm. Light sources in any of these wavelength ranges can be selected as light sources for irradiating with excitation light. In particular, 222 nm ultraviolet light is a wavelength of ultraviolet light that has recently attracted attention as germicidal ultraviolet light that has almost no effect on the human body, and active technological development is being carried out as germicidal light. Considering this background, using 222 nm ultraviolet light as excitation light is a strong option. However, according to the above considerations, light sources in the 265 nm or 280 nm wavelength range can also be selected.

[0019] The above explanation uses the example of a container made of resin and the liquid whose adhesion to its outer surface should be detected as edible oil. However, the combination of container material and liquid type may be appropriately changed as long as a wavelength range that satisfies all of the above requirements 1, 2, and 3 can be selected. A container can be a candidate for satisfying requirement 1 if it exhibits fluorescence emission in at least a specific wavelength range. The liquid does not necessarily need to exhibit fluorescence emission. A liquid that does not fluoresce in any range, or whose fluorescence intensity is sufficiently low compared to that of the container, can also be a candidate for satisfying requirement 2. On the other hand, the light transmission characteristics of the liquid must be such that, in at least a portion of the wavelength ranges that satisfy requirements 1 and 2, a wavelength range that satisfies requirement 3 can be selected. In the above example, selecting a wavelength range that satisfies requirements 1 and 2 will result in satisfying requirement 3 as well. However, the satisfaction of requirement 3 is not necessarily subordinate to the satisfaction of requirements 1 and 2. For example, if the third requirement is not met in part of the wavelength range that satisfies the first and second requirements, it is necessary to further narrow down the wavelength range of the excitation light according to the third requirement.

[0020] In the above, the transmittance of the container to excitation light was not considered. However, in containers made of PET resin, the transmittance decreases in the shorter wavelength range from around 360 nm, and the transmittance becomes almost 0% in the wavelength range of approximately 320 nm or less. In containers made of resins other than PET resin, such as polyethylene resin (hereinafter referred to as PE resin), the transmittance also decreases to almost 0% in the wavelength range of approximately 320 nm or less. Therefore, when the wavelength range of the excitation light is set to 280 nm or less as described above, the excitation light cannot be transmitted through the container, and the incidence of excitation light into the container is also blocked. In this case, even if a substance that emits fluorescence in response to excitation light in the selected wavelength range is contained in the container, the diffused fluorescence light produced by the substance inside will be transmitted through the liquid adhering to the container, and the difference in brightness between the container and the edible oil adhering to its outer surface will not be impaired as a result.

[0021] However, depending on the wavelength range of the excitation light, it is conceivable that the difference in brightness between the container and the liquid adhering to its outer surface may be impaired due to the fluorescence generated inside the container. In such cases, the excitation light wavelength range should be selected by adding a fourth requirement that the excitation light wavelength range must satisfy: that it is in a wavelength range that restricts the transmission of excitation light through the container so that the difference in brightness between the container and the edible oil adhering to its outer surface does not disappear. The term "loss of brightness difference" here is not limited to cases where the brightness difference is completely lost, but also includes cases where the brightness difference is reduced to an extent that makes it impossible to perceive. In the case where the container is filled with edible oil, the excitation light will be selected in a wavelength range that suppresses the fluorescence emission of the edible oil according to the second requirement. Therefore, even if the excitation light penetrates the container and reaches the edible oil inside, there is no risk that the fluorescence generated by the edible oil inside will make it difficult to distinguish between the edible oil on the outside of the container and the edible oil inside.

[0022] Next, with reference to Figures 4 to 7, an example of an inspection device for detecting liquid adhesion using the above method will be described. Figure 4 shows an example of an inspection device. The inspection device 1 is configured for the purpose of detecting liquid adhesion on the outer surface of a bottle 2, which is an example of a container. The inspection device 1 includes an image acquisition unit 10 that acquires an image of the bottle 2, and a processing unit 20 that processes the acquired image to detect liquid adhesion on the outer surface of the container.

[0023] Bottle 2 is, for example, a hollow, cylindrical, or polyhedral PET resin bottle. However, the container is not limited to Bottle 2 made of PET resin. The container may be made of various materials as long as it exhibits the property of fluorescing when irradiated with excitation light. For example, containers made of other resin materials such as PE resin, PP (polypropylene) resin, COP (cycloolefin polymer) resin, glass, etc., may be included. The liquid to be detected adhering to the outer surface of Bottle 2 may, for example, be edible oil to be filled as the liquid content in Bottle 2. However, the type of liquid may also be changed as appropriate, as long as the second and third requirements described above are met.

[0024] Bottle 2 is held upright, for example, with its mouth facing upwards and its axis AX aligned vertically. The image acquisition unit 10 includes an illumination device 11 as an example of illumination means for illuminating at least the inspection area of ​​bottle 2 with excitation light in a predetermined wavelength range, and an imaging device 12 as an example of imaging means for imaging bottle 2. The wavelength range of the excitation light emitted by the illumination device 11 is set to a wavelength range that satisfies the first, second, and third requirements described above. Furthermore, the wavelength range of the excitation light may be set to satisfy the fourth requirement. The illumination device 11 includes a plurality of illuminators 11a arranged symmetrically on either side of the optical axis Lp of the bottle 2 being imaged by the imaging device 12. The number of illuminators 11a may be changed as appropriate. The illumination device 11 may be configured with a single illuminator 11a.

[0025] The imaging device 12 is equipped with a camera 13 that images the inspection area of ​​the bottle 2 illuminated by the illumination device 11. The optical axis of the camera 13 corresponds to the imaging optical axis Lp of the imaging device 12. The camera 13 converts the optical image of the bottle 2 into an electrical image signal using an image sensor such as a CCD or CMOS. The camera 13 must be configured with a wavelength range set to acquire an image that reflects the difference in brightness of the fluorescence generated in the bottle 2 in response to illumination by the illumination device 11. For example, as shown in Figure 2, in a resin container, irradiation with excitation light in the wavelength range of 200 nm to 400 nm generates fluorescence in the wavelength range of approximately 360 nm to 420 nm, so the camera 13 only needs to be sensitive in at least a part of the wavelength range of 360 nm to 420 nm. Commercially available visible light cameras have sensitivity up to around 400 nm, and in some cases even slightly shorter wavelengths. Therefore, it is possible to use a visible light camera. Furthermore, since the excitation light may reflect off the bottle 2 and enter the camera 13, the imaging device 12 may be further equipped with a filter to block the reflected light from entering the camera 13. However, as mentioned above, the wavelength range of the excitation light is expected to be set to a short wavelength range of 280 nm or less, and the camera 13 is often not sensitive in that wavelength range. Therefore, even if the filter is omitted, there is no risk that the contrast of the image captured by the camera 13 will be impaired by the effect of reflected light, and it is not essential to provide a filter.

[0026] The inspection area of ​​bottle 2 may be the entire bottle 2 or only a part of it. In other words, the inspection area may be changed as appropriate, and the configuration and illumination direction of the illumination device 11 may also be changed as appropriate to match the inspection area of ​​bottle 2. Figure 4 shows an example where the shoulder of bottle 2 is set as the inspection area, and the camera 13 is positioned to image bottle 2 from vertically above with its imaging optical axis Lp aligned with the axis AX of bottle 2. The illumination device 11 is positioned to illuminate the shoulder of bottle 2 from diagonally above with a plurality of illuminators 11a arranged symmetrically around the imaging optical axis Lp. In Figure 5, the camera 13 is positioned in the same way as in Figure 4, while the illumination device 11 is positioned to illuminate the shoulder of bottle 2 from diagonally above with one or more illuminators 11a located on one side of the imaging optical axis Lp. In the example shown in Figure 5, this method is applicable when the inspection area is a portion of the shoulder of bottle 2. However, by rotating bottle 2 around its axis AX, or by rotating the illumination device 11 around axis AX, it is also possible to inspect the entire circumference of the shoulder of bottle 2 and capture an image of it.

[0027] Figures 6 and 7 show an example in which the camera 13 is positioned to image the bottle 2 from its side, and the illumination device 11 is provided with multiple illuminators 11a arranged symmetrically on either side of the imaging optical axis Lp of the camera 13. In this arrangement, an image can be acquired so that at least a part of the body of the bottle 2 is included in the inspection range. The shoulder and neck of the bottle 2 can also be included in the inspection range. By rotating the bottle 2 around the axis AX, or by rotating the illuminators 11a and the camera 13 around the axis AX, it is possible to acquire an image of the entire circumference of the bottle 2 as the inspection range. Furthermore, although not shown in the figures, by positioning the camera 13 to image the bottle 2 from below, and positioning the illumination device 11 to illuminate the bottom of the bottle 2 from an oblique direction, it is also possible to acquire an image of the bottom of the bottle 2 and detect the presence of liquid at the bottom. The illumination device 11 may be kept lit continuously, or it may be lit in a pulsed manner at a predetermined period.

[0028] In the environment in which the image acquisition unit 10 is installed, the illumination light for bottle 2 may include visible ambient light, such as natural light, as long as bottle 2 is illuminated primarily by excitation light from the illumination device 11, and an image reflecting the difference in brightness of the fluorescence produced in bottle 2 is captured by the camera 13. That is, ambient light may be blocked and bottle 2 may be illuminated only by excitation light from the illumination device 11, or some ambient light may be incident on bottle 2 as long as it does not substantially affect the image reflecting the difference in brightness of the fluorescence. Alternatively, a filter may be used to remove the influence of visible light that is unnecessary for capturing an image reflecting the difference in brightness of the fluorescence from the image captured by the camera 13.

[0029] Returning to Figure 4, the processing unit 20 of the inspection device 1 will be explained. Although the processing unit 20 is not shown in Figures 5 to 7, it is provided in the examples of Figures 5 to 7 in the same way as in Figure 4. The processing unit 20 detects the presence of liquid in the inspection area of ​​the bottle 2 based on the difference in brightness of fluorescence in the image captured by the image acquisition unit 10. The processing unit 20 is configured, for example, using a computer unit that includes a CPU and internal memory necessary for its operation. The processing unit 20 is provided with an image adjustment unit 21 and a detection unit 22. The image adjustment unit 21 and the detection unit 22 are provided as logical devices realized by a combination of, for example, the computer hardware of the processing unit 20 and an inspection program PG, which is an example of a computer program as software. However, at least a part of the processing unit 20 may be configured as a physical device combining logic circuits such as LSIs. Various input means, such as a keyboard and a pointing device, may be connected to the processing unit 20 for the operator of the inspection device 1 to input appropriate instructions. In Figure 1, the input means are not shown.

[0030] The image adjustment unit 21 receives the image signal output from the camera 13 and adjusts the image captured by the camera 13 to an image suitable for processing by the detection unit 22 by performing image processing suitable for inspection by the detection unit 22. For example, the image adjustment unit 21 may perform correction processing such as adjusting the brightness and contrast of the image. The detection unit 22 receives the image signal processed by the image adjustment unit 21 and detects the presence of liquid in the inspection area of ​​the bottle 2. Thus, the detection unit 22 functions as an example of a detection means, and its processing corresponds to an example of a procedure for detecting an object.

[0031] The detection unit 22 processes to detect liquid adhesion based on the difference in brightness of fluorescence within the inspection area. That is, when the inspection area is illuminated with excitation light in the wavelength range that satisfies the first to third requirements described above, and optionally in the wavelength range that satisfies the fourth requirement, the fluorescence intensity of the area where liquid adheres will be relatively lower than the fluorescence intensity produced in other areas of the container. Therefore, by configuring the detection unit 22 to determine whether or not a dark area corresponding to liquid adhesion appears in the image captured by the camera 13, and to determine that liquid adhesion has been detected if such a dark area exists, it becomes possible to detect liquid adhesion based on the difference in brightness in the image.

[0032] The processing of the detection unit 22 may be configured as appropriate, insofar as it includes processing for detecting the adhesion of liquid to the outer surface of the container based on the difference in brightness of fluorescence in the image. For example, the detection unit 22 may be configured to detect liquid adhesion by preparing an image of a normal bottle 2 without liquid adhesion as a reference image and calculating the difference between the image of the actually captured inspection area and the reference image. The processing of the detection unit 22 only needs to include the detection of liquid adhesion as at least part of its content. The detection unit 22 may be configured to determine the presence or absence of liquid adhesion, but is not necessarily limited to this. For example, the processing of the detection unit 22 may be configured to further determine the location of the area where liquid is adhered, the area of ​​that area, etc. If the thickness of the liquid adhering to the outer surface of the container is reflected in the brightness of the dark area itself in the image, physical quantities such as the thickness of the liquid or the amount of adhesion may be further estimated using the brightness of that dark area as a clue.

[0033] When the detection unit 22 detects the presence of liquid, the processing unit 20 may display this information on the monitor 23 or store it in the storage device 24 as an inspection result. The inspection result may include information such as the location of the area where the liquid is present and the area of ​​the liquid present. If the liquid to be filled into bottle 2 is present on the outer surface of bottle 2, it is possible that the liquid has been splashed outside bottle 2 during the filling process, or that the liquid is leaking from bottle 2. The processing unit 20 may determine that the bottle 2 in which the liquid has been detected is defective and output this determination as an inspection result. In this case, it may also notify the processing unit of the possibility of a defect in the filling process or leakage from bottle 2. The means for outputting the inspection result are not limited to the monitor 23 and the storage device 24; a printer may also be connected as an output means.

[0034] Next, using the image acquisition unit 10 of the inspection apparatus 1 in this embodiment, we will actually image a container with liquid attached to it and test whether or not a difference in brightness of fluorescence appears in the obtained image. The results of this test will be explained below in accordance with Test Examples 1 and 2 and the Comparative Example.

[0035] (Test Example 1) First, the effect of selecting ultraviolet light with a wavelength of 222 nm as the excitation light was confirmed. The illumination and imaging conditions were as follows. In Test Example 1, PET resin bottles, PE resin bottles, and glass bottles were selected as containers. The liquids used were rapeseed oil A, sesame oil, and olive oil from the edible oil samples used in the measurements in Figures 1A to 1G. The containers were filled with the samples and sealed with caps. The inspection area of ​​the container was set to the shoulder, and a portion of the edible oil sample was applied to it. The imaging direction was vertically downward. • Lighting conditions Four Care222 illuminators manufactured by Ushio Inc. were used as illuminators, and these illuminators were arranged at equal intervals around the axis of the bottle, as illustrated in Figure 4. These illuminators emit ultraviolet light with a peak wavelength of 222 nm, and the upper limit of the wavelength is 250 nm or less. The downward angle of each illuminator, that is, the angle at which the central axis of the illumination light is tilted downward with respect to the horizontal plane, was set to approximately 20°, and the distance from the light-emitting surface of each illuminator to the shoulder of the bottle was set to approximately 80 mm. The excitation light was continuously emitted. • Imaging conditions An ID2MB-CLKTS2 camera manufactured by I-JUL Corporation was used, positioned vertically downward along the bottle's axis as illustrated in Figure 4. This camera is a 2-megapixel monochrome camera using a CMOS sensor. The camera lens is a TC1614-3MP manufactured by Kenko Tokina Corporation, with a focal length of 16mm, and was used at an aperture of f / 1.4. The shutter speed was 1 / 30, the camera's imaging distance was approximately 230mm, and the imaging area was approximately 160mm x 85mm. In addition, a BP550 bandpass filter manufactured by Midwest Optical Systems (abbreviated as MidOpt), a US corporation, was attached to the lens to limit the incidence of light in the wavelength range of approximately 400nm or less to the camera. In the images shown below, the areas corresponding to the caps attached to each container have been processed to appear as dark areas. Also, the images in each figure have been cropped slightly horizontally from the camera's imaging area to exclude areas other than the containers.

[0036] Images obtained in Test Example 1 are shown in Figures 8 and 9. Figure 8 shows examples of images obtained when PET resin was selected as the container, with Figure (a) showing the case of rapeseed oil A, Figure (b) showing the case of sesame oil, and Figure (c) showing the case of olive oil. In all images, it can be confirmed that a dark area appears in region X. These dark areas roughly coincide with the area where the edible oil sample was applied.

[0037] Figure 9 shows examples of images obtained when a PE resin container and a glass bottle were selected as the container instead of a PET resin container, and rapeseed oil A was selected as the liquid. Figure 9(a) shows the case of a PE resin container, and Figure 9(b) shows the case of a glass bottle. The illumination and imaging conditions are the same as in the example in Figure 8, and the container is filled with the sample and sealed. As is clear from these figures, a dark area indicating the adhesion of edible oil appears in region X in both the case of a PE resin container and a glass bottle. Furthermore, according to Figure 9(b), a dark area indicating the adhesion of edible oil appears in region X not only in resin containers but also in glass bottles, confirming that the present invention can detect the adhesion of liquid even in containers made of materials other than resin.

[0038] (Test Example 2) Next, we confirmed the effect of selecting a wavelength of 280 nm, which was used as an example above, as the excitation light wavelength. The illumination and imaging conditions were as follows. In Test Example 1, a PET resin bottle was selected as the container. The liquids used were rapeseed oil A, sesame oil, and olive oil, from the edible oil samples used in the measurements in Figures 1A to 1G. The container was filled with the sample and sealed with a cap. • Lighting conditions Two KTDBA-43_18UV-280 illuminators manufactured by Raymac Co., Ltd. were used, and these illuminators were positioned on one side of the bottle's axis as illustrated in Figure 5. These illuminators emit ultraviolet light with a peak wavelength of 280 nm, and a lower limit wavelength of 250 nm or higher. The downward angle of each illuminator was set to approximately 15°, and the distance from the light-emitting surface of each illuminator to the shoulder of the bottle was set to approximately 40 mm. The excitation light was emitted in pulses with a constant period. • Imaging conditions For Test Example 1, the shutter speed was changed to 1 / 250, while the rest of the settings remained the same as in Test Example 1.

[0039] Figure 10 shows examples of images obtained in Test Example 2. Figure 10(a) shows the case of rapeseed oil A, Figure 10(b) shows the case of sesame oil, and Figure 10(c) shows the case of olive oil. In all images, it can be confirmed that a dark area indicating the adhesion of edible oil appears in region X. According to Figure 3, for olive oil, the light transmittance in the wavelength range around 280 nm is higher than that of other edible oils, at approximately 45%, but even in this case, a dark area appears as shown in Figure 10(c), so it can be confirmed that excitation light with a wavelength of 280 nm can be selected as excitation light capable of detecting the adhesion of edible oil.

[0040] (Comparative example) For comparison with Test Examples 1 and 2, the effect of selecting a wavelength of 365 nm as the excitation light wavelength was confirmed. The container and liquid used in the comparative example were the same as in Test Example 1. The illumination and imaging conditions were as follows. • Lighting conditions One KDUV-L110-4236A illuminator manufactured by Kyoto Electric Machinery Co., Ltd. was used, positioned on one side of the bottle's axis as illustrated in Figure 5. This illuminator emits ultraviolet light with a peak wavelength of 365 nm. The illuminator's downward angle was set to approximately 10°, and the distance from the illuminator's light-emitting surface to the bottle's shoulder was set to approximately 80 mm. The excitation light was emitted in pulses with a constant period. • Imaging conditions For Test Example 1, the shutter speed was changed to 1 / 1000, while the rest of the settings remained the same as in Test Example 1.

[0041] Figure 11 shows examples of images obtained in the comparative example. Figure 11(a) shows the case of rapeseed oil A, Figure 11(b) shows the case of sesame oil, and Figure 11(c) shows the case of olive oil. In all images, no dark areas indicating liquid adhesion appear in the bright areas corresponding to the fluorescence of the container. When the excitation light is in the wavelength range of around 365 nm, as is clear from Figures 1A, 1F, and 1G, all of the sample rapeseed oil A, sesame oil, and olive oil fluoresce, and as is clear from Figure 3, the transmittance of rapeseed oil A and olive oil is almost 100%, and even the sesame oil with the lowest transmittance shows a transmittance of about 60%. Therefore, it is thought that the wavelength range of the excitation light does not satisfy at least one of the second and third requirements mentioned above, and the difference in brightness disappears in the fluorescence of the edible oil or the fluorescence of the container behind the edible oil.

[0042] The present invention is not limited to the embodiments described above and may be implemented in any form with appropriate modifications or changes. For example, the combination of container and liquid can be appropriately selected as long as a wavelength range satisfying the first to third requirements, and if necessary, a wavelength range satisfying the fourth requirement, can be found. Insofar as there is a need to inspect for the adhesion of liquid to the outer surface of a container, the present invention is applicable as a method and apparatus for detecting the adhesion of liquid to the outer surface of a container, regardless of whether the container is filled with liquid content.

[0043] In the above embodiment, an imaging device 12 including a camera 13 was used as the imaging means, but the imaging means is not necessarily limited to the example using a camera. In the inspection of the present invention, if data showing the difference in brightness between a container and the liquid adhering to its outer surface can be obtained, it is possible to detect the presence of liquid based on the difference in brightness of fluorescence shown in that data. Therefore, data reflecting the difference in brightness of fluorescence can be obtained by using various sensors that output a detection signal corresponding to the intensity of the fluorescence to be detected, and the detection of liquid presence can be attempted based on the difference in brightness of fluorescence in the obtained data. For example, data showing the difference in brightness of fluorescence in the inspection range can be obtained using a light intensity sensor having a two-dimensional planar detection range. Alternatively, data showing the difference in brightness of fluorescence in the inspection range can be obtained by scanning the inspection range with a one-dimensional light intensity sensor (line sensor). The data obtained in this way is substantially equivalent to the image data obtained by the camera 13 in the above embodiment in that it has a signal intensity showing the difference in brightness of fluorescence. Therefore, such data is also included in the concept of "image" in the present invention, and various sensors for obtaining such data are also included in the concept of "imaging means" in the present invention.

[0044] Various aspects of the present invention derived from the embodiments and modifications described above are described below. In the following description, corresponding components shown in the accompanying drawings are indicated in parentheses to facilitate understanding of each aspect of the present invention, but this does not mean that the present invention is limited to the illustrated forms.

[0045] A method for inspecting a container according to one aspect of the present invention is a method for inspecting a container for detecting the adhesion of liquid to the outer surface of a container (2), comprising the steps of: illuminating an inspection area of ​​the container with excitation light in a wavelength range in which the container emits fluorescence; and detecting the adhesion of the liquid in the inspection area based on the difference in brightness of the fluorescence in the inspection area illuminated by the excitation light, wherein the wavelength range of the excitation light is set to a wavelength range in which the transmission of the excitation light to the liquid is limited such that the intensity of fluorescence in the liquid is relatively lower than the intensity of fluorescence produced in the container, and the difference in brightness that should occur between the container and the liquid adhering to the container disappears.

[0046] If the excitation light wavelength range is set as described above, the container will fluoresce, while the fluorescence emission from the liquid adhering to the outer surface of the container will be suppressed compared to the fluorescence emission from the container itself, resulting in a difference in brightness between the two. Furthermore, because the transmission of excitation light through the liquid is limited, the fluorescence emission of the container behind the liquid, i.e., in the area where the liquid is adhering, is also suppressed, ensuring a difference in brightness between the container and the liquid adhering to its outer surface. Therefore, if liquid is adhering to the outer surface of the container, that area will be relatively darker compared to other areas of the container. Thus, by utilizing the difference in brightness of the fluorescence generated in response to illumination by excitation light, the adhesion of liquid to the outer surface of the container can be detected.

[0047] In the inspection method according to the above embodiment, the wavelength range of the excitation light may be further set to a wavelength range in which the transmission of the excitation light through the container is restricted so that the difference in brightness that should occur between the container and the liquid adhering to the container does not disappear. If the transmission of the excitation light through the container is also restricted, even if there is a substance in the container that emits fluorescence when irradiated with excitation light, it is possible to avoid the inconvenience of the difference in brightness that should occur between the container and the liquid adhering to its outer surface disappearing due to the effect of that fluorescence emission.

[0048] The liquid may be the liquid content to be filled into the container. This makes it possible to detect splashing of the liquid content outside the container when filling it, or adhesion of the liquid content to the outer surface of the container due to leakage from the container, etc.

[0049] The liquid is edible oil to be filled into the container as the contents, and the wavelength range of the excitation light may be set to a wavelength range of 280 nm or less. This allows for proper detection of the edible oil to be filled into the container adhering to the outer surface of the container.

[0050] In the detection procedure described above, an image reflecting the difference in brightness of fluorescence in the inspection area illuminated by the excitation light may be captured, and the adhesion of the liquid in the inspection area may be detected based on the difference in brightness of fluorescence in the image. This makes it possible to detect the adhesion of liquid to the outer surface of the container using image processing technology.

[0051] An inspection device for a container (1) according to one aspect of the present invention is an inspection device for a container (2) for detecting the adhesion of liquid to the outer surface of the container, and includes: an illumination means (11) for illuminating an inspection area of ​​the container with excitation light in the wavelength range in which the container emits fluorescence; an imaging means (12) for capturing an image that reflects the difference in brightness of fluorescence in the inspection area illuminated by the excitation light; and a detection means (22) for detecting the adhesion of the liquid in the inspection area based on the difference in brightness of fluorescence in the image, wherein the wavelength range of the excitation light from the illumination means is set to a wavelength range in which the intensity of fluorescence in the liquid is relatively lower than the intensity of fluorescence produced in the container, and the transmission of the liquid is limited to a range in which the difference in brightness that should occur between the container and the liquid adhering to the container does not disappear.

[0052] According to the inspection apparatus of the above embodiment, it is possible to realize the inspection method of the above embodiment using image processing technology, and a container inspection apparatus suitable for detecting liquid on the outer surface of a container can be provided.

[0053] In the inspection apparatus of the above embodiment, similar to the inspection method of the above embodiment, the wavelength range of the excitation light may be further set to a wavelength range in which the transmission of the excitation light in the container is restricted so that the difference in brightness that should occur between the container and the liquid adhering to the container does not disappear. The liquid may be the contents to be filled into the container. The liquid may be edible oil to be filled into the container, and the wavelength range of the excitation light may be set to a wavelength range of 280 nm or less. [Explanation of Symbols]

[0054] 1. Container inspection device 2 bottles 10 Image acquisition unit 11 Lighting equipment 12 Imaging device 13 Cameras 20 Processing Units 22 Detection unit

Claims

1. A method for inspecting a container to detect the adhesion of liquid to the outer surface of the container, A procedure for illuminating the inspection area of ​​the container with excitation light in the wavelength range in which the container fluoresces, A procedure for detecting the presence of the liquid in the inspection area based on the difference in brightness of the fluorescence in the inspection area illuminated by the excitation light, Includes, A method for inspecting a container, wherein the wavelength range of the excitation light is set to a wavelength range in which the transmission of the excitation light through the liquid is limited so that the fluorescence intensity in the liquid becomes relatively lower than the fluorescence intensity produced in the container, and the difference in brightness between the container and the liquid adhering to the container disappears.

2. The method for inspecting a container according to claim 1, wherein the wavelength range of the excitation light is further set to a wavelength range in which the transmission of the excitation light in the container is restricted so as not to eliminate the difference in brightness that should occur between the container and the liquid adhering to the container.

3. The method for inspecting a container according to claim 1, wherein the liquid is the liquid content to be filled into the container.

4. The method for inspecting a container according to claim 1, wherein the liquid is edible oil to be filled into the container as the contents, and the wavelength range of the excitation light is set to a wavelength range of 280 nm or less.

5. The method for inspecting a container according to any one of claims 1 to 4, wherein the detection procedure involves capturing an image that reflects the difference in brightness of fluorescence in the inspection area illuminated by the excitation light, and detecting the presence of the liquid in the inspection area based on the difference in brightness of the fluorescence in the image.

6. A container inspection device for detecting the adhesion of liquid to the outer surface of a container, An illumination means for illuminating the inspection area of ​​the container with excitation light in the wavelength range in which the container fluoresces, An imaging means for capturing an image that reflects the difference in brightness of fluorescence in the inspection area illuminated by the excitation light, A detection means for detecting the adhesion of the liquid in the inspection area based on the difference in brightness of the fluorescence in the aforementioned image, Includes, A container inspection device in which the wavelength range of the excitation light from the illumination means is set to a wavelength range in which the fluorescence intensity in the liquid becomes relatively lower than the fluorescence intensity produced in the container, and the transmission in the liquid is limited to a range in which the difference in brightness that should occur between the container and the liquid adhering to the container does not disappear.

7. The container inspection apparatus according to claim 6, wherein the wavelength range of the excitation light is further set to a wavelength range in which the transmission of the excitation light in the container is restricted so as not to eliminate the difference in brightness that should occur between the container and the liquid adhering to the container.

8. The container inspection device according to claim 6 or 7, wherein the liquid is the liquid content to be filled into the container.

9. The container inspection apparatus according to claim 6 or 7, wherein the liquid is edible oil to be filled into the container, and the wavelength range of the excitation light is set to a wavelength range of 280 nm or less.

Images