JP7217035B2 - CONTAINER INSPECTION DEVICE AND CONTAINER INSPECTION METHOD - Google Patents

Description

TECHNICAL FIELD The present invention relates to an apparatus and the like for acquiring an image for inspecting a translucent resin container.

As a method for inspecting character strings, etc. provided on the surface of transparent or translucent resin containers, PET (abbreviation of polyethylene terephthalate; hereinafter the same applies.) resin preforms with gold imprinted as uneven patterns. For the purpose of inspecting the model number, there is known an inspection method in which the preform is illuminated from behind, an image of the preform observed from the front side is captured, and the appropriateness of the stamped portion is inspected based on the obtained image. (See Patent Document 1). On the other hand, as a method for inspecting the suitability of a label wrapped around a resin container, a label made of a resin having a lower fluorescence intensity than that of a PET resin, such as a biaxially oriented polystyrene film, is attached to the outer periphery of a PET resin bottle. An inspection method is known for inspecting the presence or absence of damage to a label by utilizing the difference between the fluorescence intensity of the label and the fluorescence intensity of the bottle when irradiated with ultraviolet light (see Patent Document 2). An inspection method is also known in which a fluorescent substance-containing layer is provided on a label to be wrapped around the outer circumference of a resin container, and the label-attached container is irradiated with ultraviolet light to inspect the presence or absence of the label and the suitability of the attachment position. (see Patent Document 3).

JP 2012-150072 A JP 2008-281477 A JP 2005-77583 A

In the inspection method of Patent Literature 1, the illumination light incident from the back side of the container passes through the inside of the container, is emitted from the front side, and enters the camera. Therefore, water droplets, bubbles, etc. (hereinafter sometimes referred to as water droplets, etc.) adhering to the inner wall of the container may appear as a dark portion in the image, degrading the detection accuracy of the inspection object such as engraving. As in Patent Documents 2 and 3, an inspection method in which a container is illuminated from one side with ultraviolet light and an image of the container is captured from the same side can suppress the influence of water droplets or the like in the container. However, the ultraviolet light reflected by the surface of the container enters the camera, reducing the difference in brightness between the container and the part to be inspected, and as a result, there is a risk that the inspection accuracy will be impaired.

Therefore, the present invention provides an image acquisition apparatus and method for acquiring an image suitable for inspecting the adequacy of an object to be inspected by suppressing the influence of reflected light on the surface of the container, and a container inspection apparatus and method using the same. intended to provide

An image acquisition device according to an aspect of the present invention is an image acquisition device for acquiring an image for inspecting a printed portion on a surface of a translucent resin container as an inspection object , wherein the container emits fluorescent light. illuminating means for illuminating the container with ultraviolet light in a wavelength range capable of illuminating the container; imaging means for capturing an image of the container that emits fluorescent light from the same side as the illumination direction of the ultraviolet light; filter means for adjusting the wavelength range of the incident light so that the wavelength range of the ultraviolet light illuminating the container is restricted compared to the wavelength range of the fluorescence generated in the container; ,

An image acquisition method according to an aspect of the present invention is an image acquisition method for acquiring an image for inspecting a printed portion on a surface of a translucent resin container as an inspection target , wherein the container emits fluorescent light. a procedure of illuminating the container with illumination means that emits ultraviolet light in a wavelength range capable of and, in the imaging step, the wavelength range of the ultraviolet light illuminating the container is limited with respect to the wavelength range of the incident light to the imaging means compared to the wavelength range of fluorescence generated in the container. , the filter means adjusts the wavelength range of the incident light.

A container inspection apparatus according to one aspect of the present invention includes the image acquisition device according to the aspect described above, and determination means for determining whether the printed portion of the container is appropriate based on the difference in brightness in the image captured by the imaging means. The discriminating means extracts the printed part as a dark part from the image captured by the imaging means, and discriminates whether or not the printed part is suitable based on the obtained image of the printed part .

A container inspection method according to an aspect of the present invention determines the suitability of the printed portion of the container based on a procedure for acquiring an image by the image acquiring method of the aspect described above and a difference in brightness in the image captured by the imaging means. and a determination step , wherein the determination step extracts the printed portion as a dark portion from the image captured by the imaging means, and determines whether the printed portion is appropriate based on the obtained image of the printed portion. is.

The figure which shows an example of the container inspection apparatus which concerns on one form of this invention. FIG. 4 is a diagram showing an example of the relationship between the spectral intensity of ultraviolet light that illuminates the bottle, the spectral intensity of fluorescence emission from the bottle, and the spectral sensitivity of the filter. The figure which shows an example of the spectral sensitivity of a camera. The figure which shows an example of the image obtained with the container inspection apparatus which concerns on one form. The figure which shows an example of the image obtained with the container inspection apparatus which concerns on a comparative example.

FIG. 1 shows a container inspection device according to one embodiment of the present invention. A container inspection device 1 is provided to inspect a PET resin bottle 2 as an example of a resin container. The object to be inspected is, as an example, the printed portion 3 provided somewhat below the support ring 2a of the bottle 2 . The bottle 2 is filled with a beverage as an example of contents. The upper end of the bottle 2 is sealed with a cap 4 . The printing part 3 is positioned somewhat above the liquid surface L of the contents. The inner wall of the bottle 2 may have water droplets or the like attached to it. FIG. 1 shows a state in which water droplets D are adhered behind a portion of the printing portion 3 . Note that FIG. 1 shows a state in which the number string "123" is printed on the printing portion 3, but this is an example. The content of the printing unit 3 may be set appropriately.

The container inspection device 1 includes an image acquisition device 10 that acquires an image for inspecting the printed portion 3 of the bottle 2 . The image acquisition device 10 includes an illumination device 11 as an example of illumination means for illuminating the bottle 2, a camera 12 as an example of an imaging means for imaging the bottle 2, and adjusting the wavelength range of light incident on the camera 12. and a filter 13 as an example of filter means.

The lighting device 11 illuminates a predetermined range including the printing portion 3 of the bottle 2 with predetermined illumination light. The bottle 2 has translucency with respect to the illumination light. Translucency is a concept that includes both transparency and translucency. The illumination device 11 is provided so as to emit, as illumination light, ultraviolet light in a wavelength range that allows the bottle 2 to fluoresce. A specific example of the wavelength range of ultraviolet light will be described later. In FIG. 1, the illumination device 11 is depicted as if it were illuminating the bottle 2 from the side of the printing unit 3, but this is a change in composition to aid understanding, and the actual arrangement is not shown. not shown. The illumination device 11 is provided so as to illuminate the inspection target such as the printing section 3 from the front side thereof.

The camera 12 converts the optical image of the bottle 2 into an electrical image signal using an imaging device such as a CCD or CMOS. The camera 12 is provided so as to capture an image of the fluorescent bottle 2 observed from the same side as the illumination direction of the illumination device 11 . The imaging range of the camera 12 is set so that an image of a predetermined range including at least the printing section 3 can be captured. Note that the bottle 2 may be stationary or may be moving. For example, the camera 12 may be installed in a beverage filling line, and the camera 12 may be caused to perform an imaging operation when the bottle 2 reaches the imaging range of the camera 12, thereby sequentially imaging the moving bottle 2. When the orientation of the inspection object such as the printing part 3 is uncertain, the bottle 2 is rotated around its center line, and the inspection object such as the printing part 3 is extended to the lighting device 11 and camera 12 side. In addition, the bottle 2 may be imaged by the camera 12 . The lighting device 11 may be lit all the time, or may be lit in synchronization with the imaging operation of the camera 12 .

The filter 13 filters the wavelength range of the incident light to the camera 12 so that the wavelength range of the ultraviolet light illuminating the bottle 2 is limited relative to the wavelength range of the fluorescence generated in the bottle 2 . adjust. A specific example of the spectral characteristics of the filter 13 will be described later. In addition, the restriction on the incidence of the wavelength range of ultraviolet light may be any one that reduces the intensity of the incident light compared to the incidence of the wavelength range of fluorescence, and completely prevents the incidence of the wavelength range of ultraviolet light. In addition, it also includes a mode in which the amount of incident light is relatively reduced. On the other hand, with respect to the wavelength range of fluorescence, it is sufficient if the amount of fluorescence required for inspection is incident on the camera 12 . The spectral characteristics of the filter 13 may be set so that the entire wavelength range of fluorescence passes through the filter 13 and is incident on the camera 12, and the incidence of a part of the fluorescence wavelength range on the camera 12 is restricted by the filter 13. may be For example, in the wavelength range of fluorescence, for a part of the wavelength range on the short wavelength side relatively close to the wavelength range of ultraviolet light as illumination light, the filter 13 restricts its passage, and the restricted wavelength range The spectral characteristics of the filter 13 may be set so that the fluorescence on the longer wavelength side passes through the filter 13 and enters the camera 12 .

According to the above configuration, the bottle 2 emits fluorescent light by illuminating the bottle 2 with the ultraviolet light emitted from the lighting device 11 . Therefore, the bottle 2 itself can function as a light source for inspecting the printed portion 3 . Since the bottle 2 emits light, even if water droplets D or bubbles adhere to the inner wall of the bottle 2, there is no possibility that the water droplets or the like appear in the image of the camera 12 as a dark portion. On the other hand, since the printed portion 3 does not emit fluorescent light, the printed portion 3 appears as a dark portion in the image of the camera 12 . Therefore, even if water droplets or the like are present, the printed portion 3 can be detected with a high degree of accuracy by sufficiently ensuring a light-dark difference between the fluorescent emission portion of the bottle 2 and the printed portion 3, and the adequacy thereof can be inspected with high accuracy. It is possible. If fluorescence generated in the bottle 2 is reflected by water droplets or the like in the bottle 2 and enters the camera 12, the water droplets or the like may appear in the image as a bright portion. However, since it is sufficient to detect the printed portion 3 as a dark portion, even if there is reflection from water droplets or the like in the bottle 2, the inspection accuracy of the printed portion 3 is not impaired.

On the other hand, when the bottle 2 is illuminated with ultraviolet light, the ultraviolet light may be reflected on the surface of the bottle 2 and the reflected light may enter the camera 12 . In that case, there is a possibility that the printed portion 3 will be projected relatively brightly and the inspection accuracy will be impaired. Filter 13 is provided to suppress the influence of reflection of ultraviolet light on the surface of bottle 2 . The wavelength range of fluorescence generated when the resin bottle 2 is illuminated with ultraviolet light shifts to the longer wavelength side than the wavelength range of ultraviolet light. Therefore, in the container inspection apparatus 1 shown in FIG. A filter 13 having spectral characteristics (spectral sensitivity) for adjusting the wavelength range of incident light is placed between the bottle 2 and the camera 12 . The filter 13 can limit the incidence of reflected light (ultraviolet light) generated on the surface of the bottle 2 to the camera 12 compared to the incidence of fluorescence generated in the bottle 2 to the camera 12 . Therefore, while suppressing the influence of the reflected light on the surface of the bottle 2, it is possible to sufficiently ensure the difference in brightness in the image between the portion of the bottle 2 that emits fluorescent light and the printed portion 3, thereby improving the inspection accuracy. .

Next, specific examples such as the wavelength range of the ultraviolet light of the illumination device 11 will be described with reference to FIGS. 2 and 3. FIG. FIG. 2 shows an example of the relationship between the spectral intensity of the ultraviolet light that illuminates the bottle 2, the spectral intensity of fluorescence emitted from the bottle 2, and the spectral sensitivity of the filter 13. FIG. In FIG. 2, the horizontal axis indicates the wavelength, and the vertical axis indicates the spectral intensity of ultraviolet light and fluorescence and the spectral sensitivity of the filter 13, respectively. FIG. 3 shows an example of the spectral sensitivity of the camera 12, where the horizontal axis indicates wavelength and the vertical axis indicates relative sensitivity.

As shown in FIG. 2, when the bottle 2 made of PET resin is illuminated with ultraviolet light whose spectral intensity peaks around 360 nm, the bottle 2 changes from a wavelength around 400 nm to a visible light region on the longer wavelength side. fluoresce. On the other hand, as shown in FIG. 3, the spectral sensitivity of a general camera used for capturing images in the visible light range is highest near 550 nm. The sensitivity of the camera 12 is substantially lost near 1000 nm on the long wavelength side and near 400 nm on the short wavelength side. More fluorescence can be obtained by setting the wavelength region of the ultraviolet light to have a peak around 320 nm. However, in that case, the wavelength range of fluorescence also shifts to the short wavelength side, and there is a possibility that the wavelength range of fluorescence will deviate from the wavelength range in which the camera 12 exhibits sufficient spectral sensitivity. Therefore, as shown in FIG. 2, the wavelength region of the ultraviolet light emitted by the illumination device 11 has a spectral intensity peak in the range of 360 nm to 380 nm, preferably in the range of 365 nm to 375 nm. It is desirable to set

On the other hand, for the filter 13, for example, a filter having a spectral sensitivity that allows passage of light beams on the longer wavelength side from around 400 nm and restricts passage of light beams on the shorter wavelength side can be used. By setting the wavelength range of the ultraviolet light and the spectral sensitivity of the filter 13 as described above, while limiting the incidence of the ultraviolet light reflected on the surface of the bottle 2 into the camera, the fluorescence generated in the bottle 2 can be detected by the camera 12. It is possible to ensure that the The wavelength range of fluorescence spreads from 400 nm to the short wavelength side, and even if the fluorescence in that portion is blocked by the filter 13, the bottle 2 emits fluorescence with sufficient intensity in the wavelength range of 400 nm or more. Even if the spectral characteristics are set as described above, the inspection of the printing portion 3 is not hindered.

Returning to FIG. 1, the description of the container inspection apparatus 1 is continued. A processing unit 20 is provided in the container inspection apparatus 1 in order to inspect the printing part 3 based on the image captured by the camera 12 . The processing unit 20 is, for example, configured as a computer unit including a CPU and an internal storage device required for its operation. The processing unit 20 is provided with an image processing section 21 and an inspection section 22 . The image processing unit 21 and the inspection unit 22 may be provided as a logical device realized by combining, for example, the hardware of the processing unit 20 and a computer program as software, or may be provided by combining logic circuits such as LSIs. may be provided as a separate physical device.

The image processing unit 21 receives image signals output from the camera 12 and performs image processing suitable for inspection by the inspection unit 22 . For example, the image processing unit 21 may perform correction processing such as brightness and contrast of the image. The inspection unit 22 receives the image signal processed by the image processing unit 21 and determines whether the printing unit 3 is suitable or not according to a predetermined algorithm. Thereby, the inspection unit 22 functions as an example of a determination unit. The algorithm for judging the propriety of the printing unit 3 may be configured appropriately as long as the propriety of the printing unit 3 is judged using the contrast in the image. For example, the inspection unit 22 binarizes the image using the difference in brightness in the image captured by the camera 12, extracts the printed part 3 as a dark part, and extracts the obtained image of the printed part 3 and the non-defective printed part. 3 may be compared to determine whether the printing unit 3 is suitable.

As means for outputting the inspection results in the inspection unit 22, the inspection unit 20 may be appropriately connected to a monitor 23 for displaying inspection results, a storage device 24 for storing inspection results, or the like. A printer may be connected as output means. Further, the inspection unit 20 may be connected to various input means such as a keyboard and a pointing device for the operator of the container inspection apparatus 1 to input appropriate instructions. In FIG. 1, the illustration of the input means is omitted.

According to the container inspection apparatus 1 configured as described above, the bottle 2 emits fluorescent light to function as a light source, and the filter 13 is used to prevent the ultraviolet light reflected from the surface of the bottle 2 from entering the camera 12. By restricting, it is possible to ensure a sufficient contrast between the bottle 2 itself and the printed portion 3, and to inspect the suitability of the printed portion 3 with high accuracy.

FIG. 4 shows an example of an image of the printed portion 3 of the bottle 2 captured using the container inspection apparatus 1 described above. As a comparative example, FIG. 5 shows an image obtained by illuminating the same bottle 2 from behind with visible light and photographing the printing portion 3 with the camera 12 from the opposite side of the illumination direction. As shown in FIG. 4, according to the container inspection apparatus 1 of the present embodiment, the bubbles of the bottle and the beverage inside the bottle appear as bright portions in the image, while the printed portions appear as dark portions in the image. is understandable. On the other hand, in the comparative example, the bubbles in the beverage appear relatively dark. Therefore, it is difficult to recognize the printed portion at the portion where the printed portion and the bubbles overlap. Furthermore, when the container inspection device 1 was installed in an actual beverage filling line and its effect was confirmed, it was found that in the conventional container inspection device, due to the influence of water droplets etc. , the defective determination rate of the printed portion was able to be reduced to about 0.06%. Since the group of bottles determined to be defective also includes bottles with defective printing, it is considered that the container inspection apparatus 1 of the present embodiment has largely eliminated the effects of water droplets and the like.

The present invention is not limited to the forms described above, and may be implemented in forms with appropriate modifications or changes. For example, the container to be inspected is not limited to a bottle made of PET resin, and the present invention can be applied to any container that emits fluorescent light when illuminated with ultraviolet rays. For example, the present invention may be applied to containers made of polypropylene resin or polyethylene resin. The object to be inspected is not limited to the printed portion, and any suitable element on the container may be set as the object to be inspected as long as the suitability can be determined by using the difference in brightness from the fluorescent light emitting portion of the container. For example, a mark or the like attached to a label that is translucent to ultraviolet light may be set as an object to be inspected.

Various aspects of the present invention derived from each of the embodiments and modifications described above are described below. In the following description, in order to facilitate understanding of each aspect of the present invention, the corresponding components illustrated in the accompanying drawings are added in parentheses, but the present invention is thereby limited to the illustrated form. not something.

An image acquisition device (10) according to one aspect of the present invention is an image acquisition device for acquiring an image for inspecting a translucent resin container (2), wherein the container emits fluorescence. Illuminating means (11) for illuminating the container with ultraviolet light in a wavelength range capable of capturing an image of the fluorescent container observed from the same side as the illumination direction of the ultraviolet light (12); With respect to the wavelength range of the incident light to the imaging means, the wavelength range of the incident light is adjusted so that the wavelength range of the ultraviolet light illuminating the container is restricted compared to the wavelength range of fluorescence generated in the container. and filter means (13) for

An image acquisition method according to one aspect of the present invention is an image acquisition method for acquiring an image for inspecting a translucent resin container (2), the container being capable of emitting fluorescent light. A step of illuminating the container with illumination means (11) emitting ultraviolet light in a wavelength range, and capturing an image of the container emitting fluorescent light from the same side as the illumination direction of the illumination means with an imaging means (12). and, in the step of imaging, the wavelength range of the ultraviolet light that illuminates the container is restricted relative to the wavelength range of the fluorescence generated in the container with respect to the wavelength range of the incident light to the imaging means. , the filter means (13) adjusts the wavelength range of the incident light.

According to the above aspect, the container itself can function as a light source when viewed from the imaging means by causing the container to emit fluorescent light. Therefore, it is possible to create a difference in brightness between the container and the inspection target on the surface thereof. Since the wavelength range of fluorescence shifts to the long wavelength side with respect to the wavelength range of the ultraviolet light that illuminates the container, the difference in the wavelength range is used to allow the reflected light (ultraviolet light) generated on the surface of the container to enter the imaging means. can be made incident on the imaging means while limiting the wavelength range of fluorescence. Therefore, while suppressing the influence of the reflected light on the surface of the container, a clear difference in brightness is generated between the fluorescence emitting portion of the container and the inspection object in the image, thereby producing an image suitable for judging the suitability of the inspection object. It is possible to obtain

In the image acquisition device of the above aspect, the illumination means illuminates the container with ultraviolet light showing a peak in a wavelength range of 360 to 380 nm, and the filter means transmits the wavelength range shorter than 400 nm to the imaging means. may limit the incidence of Further, in the image acquisition method of the above aspect, in the step of illuminating, the container is illuminated with ultraviolet light showing a peak in a wavelength range of 360 to 380 nm, and in the step of imaging, the filter means is used to a wavelength shorter than 400 nm. may be restricted to the imaging means with respect to the wavelength range of . According to these aspects, the influence of the reflected light of the ultraviolet light generated on the surface of the container on the brightness difference of the image can be reliably suppressed, and the fluorescence ray bundle generated on the container can be reliably captured by the imaging means. It is possible to acquire an image suitable for inspection.

A container inspection device (1) according to one aspect of the present invention is provided on the surface of the container based on the difference in brightness in the image captured by the image acquisition device (10) of the above aspect and the imaging means (12). and a judgment means (22) for judging the suitability of the inspection object (3) obtained.

A container inspection method according to an aspect of the present invention is provided on the surface of the container based on the procedure for acquiring an image by the image acquisition method of the above aspect and the difference in brightness in the image captured by the imaging means (12). and a procedure for determining the suitability of the inspection object (3) obtained.

According to the above aspect, it is possible to accurately inspect the suitability of the inspection target of the surface of the container by using the difference in brightness in the image obtained by the image acquisition device or method described above.

In the container inspection device and the container inspection method of the aspect described above, the inspection object may be a printed portion (3) on the surface of the container. According to this, it is possible to cause the printed portion to appear as a dark portion in the image, and to create a sufficient difference in contrast with the fluorescent container itself. Therefore, it is possible to accurately inspect the suitability of the printing unit.

1 container inspection device 2 bottle (container)
3 Printing part (inspection target)
10 image acquisition device 11 illumination device (illumination means)
12 camera (imaging means)
13 filter (filter means)
20 processing unit 22 inspection unit (discrimination means)

Claims (4)

An image acquisition device for acquiring an image for inspecting a printed portion on the surface of a translucent resin container as an inspection object, wherein the container is irradiated with ultraviolet light in a wavelength range that can cause the container to emit fluorescence. illumination means for illuminating the container; imaging means for capturing an image of the fluorescent-emitting container observed from the same side as the illumination direction of the ultraviolet light; an image acquisition device comprising filter means for adjusting the wavelength range of the incident light such that the wavelength range of the ultraviolet light illuminating the container is limited compared to the wavelength range of the fluorescence produced;
determining means for determining whether the printed portion of the container is appropriate based on the difference in brightness in the image captured by the imaging means;
with
The judging means extracts the printed part as a dark part from the image captured by the imaging means, and judges whether or not the printed part is suitable based on the obtained image of the printed part . 2. The illuminating means illuminates the container with ultraviolet light showing a peak in a wavelength range of 360 to 380 nm, and the filtering means limits the incidence of ultraviolet light on the imaging means with respect to a wavelength range shorter than 400 nm. The container inspection device according to . A procedure for acquiring an image for inspecting a printed portion on the surface of a translucent resin container as an inspection target, the illumination means emitting ultraviolet light in a wavelength range capable of causing the container to emit fluorescent light. and a procedure of capturing an image of the fluorescent container observed from the same side as the illumination direction of the illumination means with an imaging means;
a procedure for determining suitability of the printed portion of the container based on the difference in brightness in the image captured by the imaging means;
including
In the imaging step, with respect to the wavelength range of the incident light to the imaging means, the filter means is configured so that the wavelength range of the ultraviolet light illuminating the container is restricted as compared with the wavelength range of fluorescence generated in the container. adjusting the wavelength range of the incident light by
In the judging procedure, the container inspection method includes extracting the printed portion as a dark portion from the image captured by the imaging means, and judging whether or not the printed portion is suitable based on the obtained image of the printed portion . In the step of illuminating, the container is illuminated with ultraviolet light showing a peak in a wavelength range of 360 to 380 nm, and in the step of imaging, the wavelength range shorter than 400 nm is incident on the imaging means by the filter means. The container inspection method according to claim 3, wherein the

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