Test method for plastic molded articles and test device

Abstract

An inspection area of ​​a bottle 2 as a plastic molded article is illuminated with excitation light such as UV light or the like, and inspection object light such as fluorescence or the like whose wavelength range is different from the wavelength range of the excitation light is radiated from the bottle 2, the inspection area of ​​the bottle 2 illuminated with the excitation light is imaged such that the wavelength range of the inspection object light is included in the wavelength range of the imaged object while the wavelength range of the excitation light is excluded from the wavelength range of the imaged object, and based on an intensity of the inspection object light in the imaged image, a condition with respect to at least one of the shape and the structure of the plastic molded article in the inspection area, such as the presence of molding defects or the suitability of a marking portion, is inspected.

Description

TECHNICAL FIELD

[0001] The present invention relates, inter alia, to a method for testing plastic molded articles by utilizing the phenomenon that when the plastic molded article is irradiated with excitation light of a certain wavelength range, light is emitted in a different wavelength range. GENERAL STATE OF THE ART

[0002] A method for testing the suitability of a test object is known, utilizing the phenomenon that when a plastic molded article is irradiated with excitation light of a specific wavelength range, the plastic molded article emits light in a wavelength range different from the excitation light. For example, a method is proposed in which a bottle made of PET (polyethylene terephthalate) plastic is irradiated with UV light, and the bottle emits fluorescence, creating a brightness difference between the bottle and a test object such as a label wrapped around the bottle or a printed part on the bottle, and determining the quality of the test object based on this brightness difference (see, for example, Patent Documents 1 and 2). PRIOR ART DOCUMENTSPatent documents Patent Document 1: JP 2008-281477 A Patent Document 2: JP 2022-37644 A SUMMARY OF THE INVENTION OBJECT OF THE INVENTION

[0003] Plastic bottles are typically formed by blow molding a hollow, cylindrical preform. During blow molding, a molding defect in the form of a deviating wall thickness can occur due to a lack of local stretching of the plastic, caused, among other things, by errors in the shape of the preform and control errors of parameters such as temperature, which affect mold quality. Excessive stretching can also cause molecular chains to orient and compact, leading to stress whitening and other molding defects. Molding defects are not limited to blow molding. Molding defects can also occur in injection molding, for example, due to the formation of flash on the mating surfaces of the mold or the plastic filler opening, or due to inappropriate mold temperature control.Yellowing defects at the mouth may occur due to the quality of the preform raw material and unsuitable molding conditions such as heating during the preform molding stage. Since the mouth is not stretched during blow molding, yellowing at the bottle mouth may remain as a molding defect after blow molding. Quality inspections of plastic molded articles are usually relied upon by visual inspection by operators, and there is a need for improvement in inspection efficiency and quality. To save labor and automate plastic molding, there is a particular need to develop techniques for efficient and high-precision molding defect inspection.In the conventional inspection methods described above, defects such as the absence of test objects such as labels on the bottle are detected by the bottle itself acting as a light source by emitting fluorescent light, but no inspection is carried out for forming defects of the bottle.

[0004] Molding defects in plastic molded articles are caused by changes in the shape of the plastic molded article from its original shape, such as wall thickness, or by changes in the structure of the plastic molded article from its original structure, such as crystal structure, such as stress whitening or yellowing. If a method for inspecting plastic molded articles based on changes in the shape or structure of the plastic molded articles were developed, inspection methods using this method could be used not only to inspect for molding defects but also for various other conditions of the plastic molded articles, which would be advantageous in expanding the scope of these inspection methods.

[0005] In one aspect, therefore, it is an object of the present invention to provide an inspection method and the like for plastic molded articles, which can inspect the condition with respect to at least one of the shape and the structure of a plastic molded article by utilizing the phenomenon that inspection object light is emitted upon irradiation with excitation light. In another aspect, it is also an object of the present invention to provide an inspection method and the like for plastic molded articles that enables inspection for molding defects with high efficiency and accuracy, or to provide an inspection method and the like that enables inspection of marking portions attached to the plastic molded article with high efficiency and accuracy. MEANS TO SOLVE THE TASK

[0006] An inspection method for plastic molded articles according to one aspect of the present invention is an inspection method for inspecting plastic molded articles, comprising the steps of: illuminating an inspection area of a plastic molded article with excitation light capable of being emitted from the plastic molded article with inspection object light having a wavelength range different from that of the emitted light, capturing the inspection area of the plastic molded article illuminated with the excitation light such that the wavelength range of the inspection object light is included in the wavelength range of the image object while the wavelength range of the excitation light is excluded from the wavelength range of the image object, and inspecting a condition with respect to at least one of the shape and the structure of the plastic molded article in the inspection area based on an intensity of the inspection object light in the captured image.

[0007] An inspection apparatus for plastic molded articles according to one aspect of the present invention is an inspection apparatus for inspecting plastic molded articles, comprising: means for illuminating an inspection area of a plastic molded article with excitation light that can be emitted from the plastic molded article, with inspection object light having a wavelength range different from that of the emitted light; means for recording the inspection area of the plastic molded article illuminated with the excitation light such that the wavelength range of the inspection object light is included in the wavelength range of the recording object, while the wavelength range of the excitation light is excluded from the wavelength range of the recording object;and means for inspecting a condition with respect to at least one of the shape and the structure of the plastic molded article in the inspection area based on an intensity of the inspection object light in the captured image. BRIEF DESCRIPTION OF THE CHARACTERS Fig. 1 shows an example of a test apparatus used in a test method of an embodiment. Fig. Figure 2 is a view showing 3D fluorescence spectra of polyethylene terephthalate plastic samples under UV light irradiation. Fig. Figure 3 shows an example of the relationship between the spectral intensity of UV light illuminating a bottle, the spectral intensity of fluorescence emission from the bottle, and the spectral sensitivity of a filter. Fig. Figure 4 shows an example of the spectral sensitivity of a camera. Fig. 5A shows an example of a forming defect that is the test object in the test method of an embodiment. Fig. 5B shows an example of a forming defect which is the inspection object in the inspection method of the embodiment. Fig. 5C shows an example of a forming defect which is the inspection object in the inspection method of the embodiment. Fig. Figure 6A is a photograph showing an example of fluorescence emission when there is no molding defect at a shoulder portion of a proper bottle. Fig. Figure 6B is a photograph of an example of fluorescence emission when a defect with a different wall thickness is present at a shoulder portion of a bottle. Fig. Figure 7A is a photograph of an example of fluorescence emission when there is no molding defect at a bottom portion of a sound bottle. Fig. Figure 7B is a photograph of an example of fluorescence emission when a defect with core deviation is present at a bottom portion of a bottle. Fig. Figure 7C is a photograph of an example of fluorescence emission when stress whitening and a molding defect with a different wall thickness are present at a bottom portion of a bottle. Fig. Figure 8A is a photograph showing an example of fluorescence emission when there is no molding defect at a corner portion of a proper bottle. Fig. Figure 8B is a photograph of an example of fluorescence emission when stress whitening occurs at a corner portion of a bottle. Fig. Figure 9A is a photograph of an example of fluorescence emission when there is no molding defect on a belly portion of a sound bottle. Fig. Figure 9B is a photograph of an example of fluorescence emission when slight stress whitening is present on a belly portion of a bottle. Fig. Figure 9C is a photograph of an example of fluorescence emission when significant stress whitening is present on a ventral portion of a bottle. Fig. Figure 10A is a photograph showing an example of fluorescence emission when there is no molding defect at a mouth portion of a proper bottle. Fig. 10B is a photograph showing an example of fluorescence emission when yellowing occurs at a mouth portion of a bottle. Fig. 11A is a view of an example of a medical syringe having a molding defect at the injection port. Fig. Figure 11B is an example of a photograph taken in the wavelength range of UV light from the forming defect Fig. 11A was recorded. Fig. Figure 11C is an example of an image taken in the wavelength range of fluorescence emission from the forming defect Fig. 11A was recorded. Fig. 12A is a view of an example of a medical syringe having a molding defect at the flange portion. Fig. 12B is an example of a magnified image of the forming defect from Fig. 12A. Fig. Figure 12C is an example of a photograph taken in the UV wavelength range of the forming defect Fig. 12A was recorded. Fig. Figure 12D is an example of an image taken in the wavelength range of fluorescence emission from the forming defect Fig. 12A was recorded. Fig. 13 is an example of a photograph of a marking portion formed by laser marking and its surroundings in the wavelength range of fluorescence emission. Fig. 14 is an example of a shot using the same bottle as in Fig. 13 with visible light in the wavelength range of the illuminating light. Fig. 15 is an example of a photograph of a marking portion formed by unevenness in a neck portion and its surroundings in the wavelength range of fluorescence emission. EMBODIMENT OF THE INVENTION

[0008] An embodiment of the present invention will be described below with reference to the accompanying figures. In the inspection method of the present embodiment, when a plastic molded article is irradiated with excitation light of a specific wavelength range, light of a wavelength range different from the wavelength range of the excitation light is irradiated as inspection light, and the plastic molded article is inspected based on the intensity of the inspection light and the manner in which the intensity of the inspection light changes in response to a condition related to the shape and structure of the plastic molded article. The shape here includes various characteristic aspects of the condition of the external shape of the plastic molded article, such as its wall thickness and unevenness.The structure includes various characteristic aspects of the material properties of the plastic molded article, such as crystal structure and microstructure. The nature of the test object can include various properties related to the shape and structure. An embodiment of the testing method and the like will be described below using examples of molding defects of the plastic molded article. Molding defects in plastic molded articles are caused by changes in the shape of the plastic molded article from its original shape, such as wall thickness, or by changes in the crystal structure or microstructure of the plastic molded article from its original structure, such as stress whitening or yellowing.There is a relationship between the intensity of the test object light emitted when the plastic molded article is irradiated with excitation light and the shape and structure of the plastic molded article. For example, the intensity of the test object light increases with increasing wall thickness or density of the plastic molded article. The presence of molding defects can be inspected based on this property.

[0009] Fig. 1 shows an example of a test apparatus used in a test method of an embodiment. The test apparatus of Fig. 1 inspects for the presence of molding defects using UV light of a specific wavelength range as an example of the excitation light and fluorescence, which occurs in response to the radiation of UV light, as the inspection object light. The plastic molded article constituting the inspection object is, as an example, a bottle 2. The inspection device 1 includes an image acquisition unit 10 that acquires images based on fluorescence of the bottle 2 and a processing unit 20 that processes the acquired images and inspects for the presence of molding defects. The bottle 2, as an example, is formed by blow-molding a substantially hollow, cylindrical preform (preliminarily molded body) of PET plastic in a predetermined shape (molding die).A belly portion 2a of the bottle 2 is substantially cylindrical, while a shoulder portion 2c between a neck portion 2b and the belly portion 2a is substantially frustoconical. A bottom portion 2d has a shape in which its central portion is recessed inward along an axis AX. Examples of molding defects will be described later.

[0010] The image pickup unit 10 includes an illumination device 11 as an example of the illumination device for illuminating the bottle 2 and an image pickup device 12 as an example of the image pickup device for recording the bottle 2. The illumination device 11 illuminates an inspection area of the bottle 2 with a predetermined illumination light. The inspection area can be the entire bottle 2 or a part of the bottle 2. The illumination device 11 emits UV light as illumination light, which can cause fluorescence emission on the bottle 2. Specific examples of the wavelength range of the UV light are described below. In the example from Fig. 1, a range from the belly portion 2a to the shoulder portion 2c of the bottle 2 is defined as the inspection area. The illumination device 11 includes, as an example, an upper lamp 11a that illuminates the inspection area obliquely from above and a lower lamp 11b that illuminates the same inspection area of the bottle 2 obliquely from below. However, the inspection area of the bottle 2 can be changed as described above, and the configuration and illumination direction of the illumination device 11 can also be changed as needed to match the inspection area of the bottle 2. For example, when inspecting the neck portion 2b and the shoulder portion 2c of the bottle 2, the illumination device 11 and the image pickup device 12 can be arranged to match these positions.When the bottom portion 2d is inspected, a camera 13 of the image pickup device 12 may be arranged below the bottle 2 and its optical pickup axis Lp may be aligned with the axis AX, and also the illumination device 11 may be arranged to illuminate the bottom portion 2d from the oblique direction.

[0011] The image recording device 12 includes a camera 13 and a filter 14 that limits the wavelength range of the light incident on the camera 13 to a range suitable for inspection. The camera 13 converts optical images of the bottle 2 into electrical image signals using, for example, image sensors such as CCD or CMOS or the like. The camera 13 records the inspection area of the bottle 2 where fluorescence emission occurs. The recording direction is set, as an example, such that the bottle 2 is recorded from the same side as the illumination direction of the illumination device 11. In the example of Fig. 1, the optical recording axis Lp of the camera 13 is directed in the horizontal direction, while the lights 11a, 11b and the camera 13 are arranged such that the optical axes La, Lb of the lights 11a, 11b extend symmetrically with the optical recording axis Lp therebetween. The recording direction does not necessarily have to be set on the same side as the direction of illumination with the UV light, as long as an image is recorded in which the intensity distribution of the fluorescence occurring on the bottle 2 is clearly visible. Depending on the inspection area of the bottle 2, the illumination direction and the recording direction may be in a different relationship than in Fig. 1 such that the bottle 2 is illuminated in the axial direction and the camera 13 records from the side of the abdominal section.

[0012] The shooting range of the camera 13 can be set so that at least one image of the inspection area of the bottle 2 can be captured. During the inspection, the bottle 2 can be stationary or moving. For example, the camera 13 can be installed on a beverage bottling line, and when a bottle 2 reaches the shooting range of the camera 13, a shooting operation of the camera 13 can be performed to capture the moving bottles 2 one after another. If the entire circumference of the bottle 2 is captured as the inspection area, and only a part of the inspection area can be captured with a single camera 13 in a single shooting operation, images of the entire inspection area can be created by controlling the shooting operation of the camera 13 so that the bottle 2 is rotated and the entire circumference of the bottle 2 is captured in multiple shooting operations.The bottle 2 can also be fixed, and the lighting device 11 and the image recording device 12 can be moved around the bottle 2 to create images of the entire inspection area. Multiple cameras 13 can also be provided, which record the bottle 2 from different directions, and the inspection area of the bottle 2 can be recorded circumferentially by dividing these cameras 13. The lighting device 11 can be continuously illuminated or controlled so that it illuminates simultaneously with the recording process of the camera 13. The inspection area does not necessarily have to be defined to the entire circumference of the bottle 2. Nor does the inspection area necessarily have to be defined to an area with a specific extent.For example, a plurality of point detection positions may be defined on the bottle 2, and the entirety of these detection positions may serve as an inspection area, and the captured images of each detection position may be captured as images of the inspection area by the camera 13. To capture such an image, for example, the camera 13 may output the image signal of the pixel group corresponding to the detection position as the readout object of the image signal from the camera 13, or the camera 13 may output an image signal corresponding to the pickup area of the image sensor and extract the image signal corresponding to the detection position from this image signal to obtain the image of the detection area. When the entirety of the point detection positions constitutes the inspection area, the inspection accuracy can be increased by increasing the number of detection positions.In any case, the shooting range of the camera 13 may be set to include the inspection range, and the inspection range may be set as at least a part of the shooting range of the camera 13.

[0013] The filter 14 adjusts the wavelength range of the light incident on the camera 13 such that, with respect to the wavelength range of the subject being photographed by the camera 13, the wavelength range of fluorescence occurring on the bottle 2 is included in the wavelength range of the subject being photographed, while the wavelength range of UV light illuminating the bottle 2 is excluded from the wavelength range of the subject being photographed. However, the spectral properties of the filter 14 do not necessarily have to be set such that the UV light wavelength range is completely blocked from entering the camera 13.The transmission of the wavelength range of UV light can be restricted at the filter 14 to such an extent that the image captured by the camera 13 has a brightness distribution reflecting the distribution of the fluorescence intensity, and the influence of the wavelength range of the UV light on the brightness distribution is essentially removed from the image. In other words, the spectral properties of the filter 14 can be set such that, with respect to the wavelength range of the light incident on the camera 13, the wavelength range of the UV light with which the bottle 2 is illuminated is restricted compared to the wavelength range of the fluorescence occurring on the bottle 2.In this regard, the filter 14 is not limited to completely preventing the incidence of the wavelength range of UV light, and it is sufficient if it reduces the amount of incident light in the wavelength range of UV light compared to the wavelength range of fluorescence.

[0014] On the other hand, for the fluorescence wavelength range, it is sufficient if the amount of fluorescent light required for inspection enters the camera 13. The spectral characteristics of the filter 14 can be set so that the entire fluorescence wavelength range passes through the filter 14 and enters the camera 13, or so that part of the fluorescence wavelength range is blocked by the filter 14 from entering the camera 13. For example, the spectral characteristics of the filter 14 can be set so that, of the fluorescence wavelength range, the filter 14 blocks a part of the wavelength range on the shorter wavelength side, which is relatively close to the wavelength range of the UV light serving as the illumination light, and the fluorescence on the longer wavelength side, as the restricted wavelength range, passes through the filter 14 and enters the camera 13.

[0015] The reason for limiting the wavelength range of the object being photographed by the filter 14 is as follows: The light from the bottle 2 to the camera 13 contains not only the fluorescence occurring on the bottle 2 but also the UV light reflected by the bottle 2. When the UV light enters the camera 13, the influence of the UV light is evident in the acquired image, so there is a risk of hindering the inspection for molding defects based on the fluorescence intensity distribution. However, the wavelength range of the fluorescence occurring on PET plastic does not match the wavelength range of the emitted UV light, and there is a wavelength discrepancy between them.Therefore, if the spectral characteristics of the filter 14 are set so that the wavelength range of fluorescence is included in the wavelength range of the subject of the camera 13 while excluding the wavelength range of UV light from the subject of the camera 13, images can be captured in which the influence of the reflected light from the bottle 2 is suppressed and the intensity distribution of fluorescence is accurately reflected. As a means for selecting the wavelength range of the subject, it is not necessary to use a filter 14 separate from the camera 13. For example, the camera 13 may have a function for selecting the wavelength range to which the image sensor of the camera 13 is sensitive, and the wavelength range of the subject of the camera 13 can be adjusted using this function.If the reflected light from the bottle 2 contains a higher-order light component, such as secondary light with twice the wavelength of the excitation light, which is different from the wavelength range of the excitation light and the fluorescence to be used as the detection object and represents a noise component, and this noise component affects the brightness differences in the image, the spectral properties of the filter 14 and the sensitivity of the camera 13 can be set so that the noise component is also excluded from the wavelength range of the recording object.

[0016] The illumination light of the bottle 2 in the environment where the image pickup unit 10 is installed may also include ambient light in the visible range, such as natural light, as long as the illumination of the bottle 2 is mainly provided by the illumination light of the illumination device 11, and an image reflecting the intensity distribution of the fluorescence occurring on the bottle 2 is captured by the camera 13. Thus, ambient light may be blocked and the bottle 2 may be illuminated only with the illumination light from the illumination device 11, or some ambient light may be incident on the bottle 2, as long as it substantially does not affect the image reflecting the intensity distribution of the fluorescence.It is also possible to exclude the influence of visible light, which is not necessary for taking the image reflecting the fluorescent light intensity, from the image taken by the camera 13 by means of the filter 14 or the like.

[0017] Next, with reference to Fig. 2 to 4, concrete considerations regarding the selection of the wavelength range of the UV light of the illumination device 11 and the like are described. Fig. Figure 2 is a view showing 3D fluorescence spectra of PET plastic samples under UV light irradiation. The vertical axis is the wavelength of the emitted UV light, and the horizontal axis is the wavelength of fluorescence. The density of the contour lines in the image indicates the fluorescence intensity, and the denser the lines, the higher the fluorescence intensity. Fig. 2 When PET plastic is irradiated with UV light in the range of 365 nm, a comparatively strong fluorescence occurs in the wavelength range from 380 to 430 nm.

[0018] Fig. Figure 3 shows the relationship between the spectral intensity of UV light illuminating bottle 2, the spectral intensity of the fluorescence emission of bottle 2, and the spectral sensitivity of filter 14. The horizontal axis in Fig. 3 shows the wavelength and the vertical axis respectively the spectral intensity of UV light and fluorescence and the spectral sensitivity of the filter 14. As can be seen from Fig. 3, when PET plastic is irradiated with UV light, the spectral intensity of which peaks at 365 nm, fluorescence occurs in the wavelength range from 380 to 430 nm. The distribution of the spectral intensity of the UV light and the distribution of the spectral intensity of the fluorescence partially overlap, and if the wavelength range of the UV light is between 360 nm and 380 nm and the spectral properties of the filter 14 are set such that long-wave light from approximately 400 nm is transmitted and shorter wavelength ranges are blocked, the incidence of UV light into the camera 13 is prevented, while the fluorescence occurring on the bottle 2 can enter the camera 13 with high efficiency.

[0019] According to Fig. 2, even more fluorescent light can be obtained by setting the UV wavelength peak at 320 nm. However, in this case, the fluorescence wavelength range also shifts to the shorter wavelength side. As shown in Fig. As shown in Figure 4, the spectral sensitivity of a conventional camera used to capture images with visible light is highest at 550 nm. The camera's sensitivity is essentially lost at 1000 nm on the long-wavelength side and at 400 nm on the short-wavelength side. Therefore, if the wavelength range of the UV light is set to 320 nm, there is a risk that the wavelength range of fluorescence will deviate from the wavelength range in which the camera 13 has sufficient spectral sensitivity. Therefore, the UV light emitted by the illumination device 11 is preferably set to the range of 360 nm to 380 nm.

[0020] Next, with reference to Fig. 5A to 5C describe examples of molding defects inspected in the inspection method of the present embodiment. During blow molding of the bottle 2, the preform is heated to the glass transition temperature and softens into a rubbery state, and by stretching the preform in this state with a stretch rod in the direction of the axis AX of the bottle 2 ( Fig. 1) When gas pressure is introduced into the preform, the preform is stretched in two axial directions, vertically and horizontally, and then solidified by cooling. If the preform has a shape deviation or there are deficiencies in various operations and controls during the molding process, such as temperature control related to resin heating, such as the heating power (heating rate) for heating the preform, the stretching process with the stretch rod, the temperature control of various parts of the mold, etc., the preform may not be stretched homogeneously, and molding defects may occur. For example, if the stretching is locally insufficient, a wall thickness deviation defect in which the wall thickness is not uniform may occur. Fig. 5A shows an example in which a section D1 with a different wall thickness has occurred at the shoulder section of the bottle 2, and Fig. Figure 5B shows an example in which a section D2 with a different wall thickness has occurred at the bottom section of bottle 2. It also happens that, as in Fig. As shown in Figure 5C, a core deviation section D3 is created in the base section when the stretching process is uneven. The core deviation section D3 is created because, where a relatively thick core section should actually be formed around the axis AX of the base section of bottle 2, the wall thickness is offset from the center of the base section due to the uneven stretching. Therefore, the core deviation section D3, like the sections D1 and D2 with deviating wall thickness, can be considered a type of defect with deviating wall thickness. Defects with deviating wall thickness can also occur in other locations, such as the belly section.

[0021] In places where the polymer has been stretched too much, the molecular chains become oriented and compressed, leading to crystallization. As a result, molding defects with altered microstructures arise, accompanied by visible-light discolorations such as stress whitening or yellowing. Yellowing occurs during the molding of the preform but is considered a type of molding defect in the bottle because it remains after blow molding. These types of molding defects are also referred to as microstructural defects. As described in Fig. For example, as shown in Figure 5C, a stress whitening portion D4 is formed at or near the corner portion that forms the boundary between the bottom portion and the belly portion of the bottle 2. Although not shown, a deformation in which the mouth portion of the bottle 2 curves abnormally also results in an increased wall thickness around this altered location, thus resulting in a defect with a deviating wall thickness. Or a structural defect occurs in which the mouth portion or the bottom portion of the bottle 2 partially or entirely exhibits stress whitening or yellowing.

[0022] At the locations where these defects with deviating wall thickness or structural defects occur, the intensity of the fluorescence resulting from UV light irradiation is different from the range of fluorescent light intensity without these defects. In the case of a defect with deviating wall thickness, the fluorescent light intensity at the location with the unusually thick wall thickness increases compared to the normal. In the case of a structural defect, the fluorescent light intensity increases compared to the normal due to the unusual plastic density. Using this change in fluorescent light intensity as a reference point, it is possible to detect the occurrence of forming defects such as defects with deviating wall thickness or structural defects. Fig. 6A to 10B show examples of actual images of bottles 2 taken with the testing device 1 of Fig. 1. In all images, the higher the fluorescent light intensity, the higher the brightness.

[0023] Fig. 6A and Fig. 6B are examples in which the area of the boundary between the neck section and the shoulder section was recorded, where Fig. 6A a picture of a normal bottle without any forming defects and Fig. Figure 6B is an image of a bottle with a wall thickness defect in area X1. A comparison of these images shows that the fluorescent light intensity is higher than normal at the location with increased wall thickness due to the wall thickness defect. Fig. 7A to 7C are examples in which the bottom section of the bottle was photographed, where Fig. 7A is a picture of the bottom portion of a normal bottle without forming defects, Fig. 7B an image of the soil section with core deviation and Fig. 7C is an image in which stress whitening occurs on the outer periphery of the base section and a deviating wall thickness is present in the area X3 on the midpoint side of the base section. In the image of Fig. 7B with nuclear deviation is compared to the normal image of Fig. 7A, the area X2 with increased fluorescent light intensity is enlarged and its position is also offset compared to the normal image. In the image of Fig. 7C with different wall thickness and whitening is compared to the normal image of Fig. 7A, the influence of stress whitening is clearly visible on the outer perimeter of the base section, and the influence of the different wall thickness is clearly visible on the center side. Together with the different wall thickness in the middle section in the example of Fig. 7C, there is a state of excessive stretching on the outer peripheral side of the bottom portion and, as a result, increased density and crystallization, and it is suspected that this is also a factor in the occurrence of the defect.

[0024] Fig. 8A and Fig. 8B are examples where the corner section on the bottom side of the bottle is cut diagonally from below into Fig. 1 was recorded, whereby Fig. 8A a picture of a normal bottle without any forming defects and Fig. Figure 8B is an image of a bottle with stress whitening in the X4 area. A comparison of these images shows that the fluorescent light intensity at the stress whitening site is higher than normal. Fig. 9A to 9C are examples in which a part of the belly section of the bottle was taken, where Fig. 9A a picture of a bottle without molding defects, Fig. 9B a picture of a bottle with slight whitening and Fig. Figure 9C is an image of a bottle with significant stress whitening. A comparison of these images also shows that the fluorescent light intensity at the stress whitening site is higher than normal. Fig. 10A and Fig. 10B are examples in which the mouth portion of the bottle was recorded, where Fig. 10A a picture of a normal bottle without any forming defects and Fig. Figure 10B is an image of a bottle in which a molding defect with yellowing occurred substantially throughout the entire mouth portion. A comparison of these images shows that the fluorescent light intensity at the yellowing location is higher than normal. The cause of the yellowing is not entirely clear, but one suspected factor is that local crystallization occurred during the molding of the preform due to poor molding conditions, which increased the absorption efficiency of the specific wavelength range and thus caused yellowing.

[0025] As can be seen from the above image examples, at the locations where these defects with deviating wall thickness or structural defects occur, the intensity of the fluorescence generated due to UV light irradiation is different from the range of normal fluorescent light intensity when there are no forming defects. Therefore, it is possible to detect the presence of forming defects based on the fluorescence intensity in the image of a bottle where fluorescence emission has occurred. For example, the presence of forming defects can be detected by judging whether there is a location in an image with a fluorescent light intensity outside the range of fluorescent light intensity that should exist without forming defects (for example, a fluorescent light intensity that is higher than normal).More specifically, it can be checked whether a relatively bright part with high fluorescent light intensity appears in a location where a normal bottle without forming defects would have relatively low fluorescent light intensity and therefore would appear dark in the image. If such a bright part appears, it can be judged that a forming defect has occurred. Even if a dark part appears in a location that should be bright in a normal bottle, this can be recognized as a forming defect. It is also possible to determine in advance the fluorescent light intensity that can be expected when a defect with a deviating wall thickness or a structural defect occurs, and based on whether there are locations with such fluorescent light intensity in the image, the presence of forming defects can be detected.

[0026] As in Fig. 7A, sometimes even in a normal bottle, a certain area around the core section of the base section as the center appears as a bright part, or, as in Fig. As shown in Figure 8A, even with a normal bottle, a part of the image appears as a bright part depending on the shooting direction of the bottle. Even if such a bright part appears, its area, intensity, etc., varies depending on whether or not there is a forming defect. Therefore, if the fluorescent light intensity distribution is used as a benchmark, it is possible to detect the presence of forming defects by examining the differences in the fluorescent light intensity distribution (brightness distribution) in the captured image. When detecting the presence of forming defects, not only differences in intensity but also positional differences in the intensity distribution can be taken into account. Therefore, not only information on the agreement or non-conformity of the intensity but also information on the agreement or non-conformity of the intensity can be obtained.Positional inconsistency can be taken into account during testing. For example, it can be assessed whether the position of a spot of a certain intensity is consistent with the normal case, and if the position deviates, it can be judged that a forming defect exists or may exist.

[0027] Returning to Fig. 1, the processing unit 20 of the inspection apparatus 1 will now be described. The processing unit 20 inspects the presence of forming defects based on the fluorescent light intensity in the images captured by the image pickup unit 10. As an example, the processing unit 20 is configured using a computer unit including a CPU and an internal storage device, etc., required for its operation. An image adjustment unit 21 and an inspection unit 22 are provided in the processing unit 20. The image adjustment unit 21 and the inspection unit 22 are provided as logical devices implemented, for example, by a combination of 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 and the like. Various input devices such as keyboards and pointing devices may be connected to the processing unit 20 so that an operator of the test apparatus 1 can input corresponding instructions thereto. In . Fig. 1 the input device was not shown.

[0028] The image adjustment unit 21 receives an image signal output from the camera 13 and, by performing image processing suitable for inspection by the inspection unit 22, adjusts the image captured by the camera 13 so that it is suitable for inspection by the inspection unit 22. For example, the image adjustment unit 21 can perform correction processing on the brightness, contrast, etc. of the image, and the like. The inspection unit 22 receives the image signal processed by the image adjustment unit 21 and checks for the presence of molding defects. Thus, the inspection unit 22 functions as an example of an inspection device.

[0029] The processing of the inspection unit 22 can be configured appropriately as long as the presence of molding defects can be detected based on the fluorescent light intensity in the images. For example, the inspection unit 22 can binarize based on brightness differences in the image captured by the camera 13, determining areas where the fluorescent light intensity exceeds a predetermined judgment value as bright parts and other areas as dark parts. If a bright part appears at a location where there is no bright part in the image of a good bottle, it can recognize this location as a molding defect.As discussed above, an inspection procedure can be configured to prevent a bright portion from being mistakenly judged as a molding defect even in a good bottle, even if it appears as a bright portion with relatively high fluorescent light intensity. For example, an image of a good bottle can be taken as a reference image, the difference between the image of the actually acquired inspection area and the reference image can be measured, and if a bright portion appears in a location that should be a dark area in the reference image, this bright portion can be judged as a molding defect.Alternatively, a mask may be created showing the area where a bright part appears in the case of a normal bottle without taking differences into account, and then the mask is superimposed on the image of the actually acquired inspection area to exclude the area where the bright part also appears in the normal case from the area where bright parts are detected by the inspection unit 22. Even if a dark part appears at a position where a bright part exists in a normal bottle, this may be detected as a molding defect. If the inspection unit 22 judges that a molding defect exists, it may display the defect location as an inspection result on a monitor 23 or store it in a storage device 24. The output means of the inspection result is not limited to the monitor 23 and the storage device 24, and a printer may also be connected as the output means.

[0030] As described above, in the inspection apparatus 1 of the present embodiment, the inspection area of the bottle 2, which is the inspection object, can be illuminated with the UV light of the illumination device 11, and the image of the bottle 2 where fluorescence emission has occurred can be captured by the camera 13 such that the wavelength range of the fluorescence is included in the wavelength range of the image object while excluding the wavelength range of the UV light from the wavelength range of the image object, and the presence of molding defects can be inspected at the inspection unit 22 based on the fluorescent light intensity in the captured image. According to this inspection method, the presence of molding defects can be inspected by image processing without relying on visual inspection by workers, and therefore the presence of molding defects can be inspected with high efficiency and accuracy.It is also possible to apply the testing device 1 to a bottle forming line and continuously check for the presence of forming defects.

[0031] The present invention is not limited to the above-described embodiment and is applicable to the inspection of various molding defects on plastic molded articles serving as an inspection object. The plastic molded article is not limited to the example of formation by blow molding and may also be formed by injection molding. The excitation light used to illuminate the plastic molded article is not limited to UV light. For the excitation light, it is sufficient if light whose wavelength range is different from the wavelength range of the illumination light can be radiated from the plastic molded article, and excitation light in which Raman scattered light is radiated as the inspection object light may also be used for illumination. Thus, the excitation light is not limited to the UV range and may also include the wavelength range of visible light.As long as the wavelength range of the inspection object light is different from the excitation light, and an image of the wavelength range of the inspection object light can be acquired while excluding the image of the wavelength range of the excitation light, the combination of the excitation light and the inspection object light can be appropriately changed. Also, the material of the plastic molded article is not limited to PET plastic, and various materials can be used as long as they have the property of emitting light in a different wavelength range from that of the excitation light when irradiated with excitation light such as UV light or the like. The plastic molded article constituting the inspection object is not limited to a bottle-shaped container, and as long as they are formed by blow molding, plastic molded articles for various purposes can serve as the inspection object. Fig. 11A to 12D show examples in which a plastic molded article other than a PET bottle serves as the test object.

[0032] Fig. 11A to 12D show a medical syringe with a molding defect. The medical syringe is an example of a plastic molded article and is injection molded using COP (cycloolefin polymer) resin as the material. Fig. 11A to 11C are examples in which a discharge port P of the syringe is the test area, where Fig. 11A is a drawing view of a syringe in which a molding defect has actually occurred in the area of the dispensing opening, Fig. 11B a picture of the test area of Fig. 11A is a real syringe illuminated with UV light, the reflected light of the UV light being taken from the direction directly opposite (axial with) the dispensing opening P, and Fig. 11C is an image taken from the same area and direction as in Fig. 11B, where the wavelength range of the object was limited to the wavelength range of the fluorescence emission. As in Fig. As shown in Figure 11A, a burr D5 has formed on the inner surface of the discharge opening P as a molding defect. The burr D5 is caused by the compaction and crystallization of the plastic in the mold and can be considered as a type of the above-mentioned structural defect. Fig. 11B and Fig. 11C the ridge appears as a bright part, whereby in Fig. 11B, which is an image of the reflected light of the UV light, the other normal parts except the ridge also appear as bright parts, making it difficult to distinguish. Fig. However, in Figure 11C, which is the image of the wavelength range of fluorescence, as shown in area X5, the part with the ridge exhibits a fluorescence emission of significantly higher intensity than the other parts.

[0033] Fig. 12A to 12D are examples where a flange portion of the syringe is the test area. The flange portion is located opposite the syringe discharge port and is a part where the finger rests when operating the syringe, and is molded integrally with the cylindrical portion of the syringe. Fig. 12A is a drawing view of the flange portion of the syringe in which a molding defect actually occurred. A pair of recessed portions C are formed on a diagonal line at the flange portion, and one of the recessed portions C has a defect D6, a so-called gate horn. Fig. Figure 12B shows an enlarged image of an actual defect D6. The defect D6 is a molding defect caused by poor handling in the area of the sprue (gate) for the plastic to enter the mold and a spot caused by the compaction and crystallization of the plastic in the mold, which can be considered a type of the above-mentioned structural defect.

[0034] Fig. 12C is an image created by illuminating the entire Fig. 12B with UV light as the test area and the image of the reflected light of the UV light was taken from the direction directly opposite the flange (in the axial direction), and Fig. 12D is an image taken from the same area and direction as Fig. 12C, whereby the wavelength range of the object was limited to the wavelength range of the fluorescence emission. In Fig. 12C and Fig. 12D, markers placed during image processing are shown as thin white lines, but these do not indicate the intensity of the reflected light or fluorescence. In the UV light image from Fig. 12C, it is impossible or difficult to distinguish the part corresponding to defect D6. In the image of Fig. However, in Figure 12D, which is the image of the wavelength range of fluorescence, as shown in region X6, the part with defect D6 exhibits a fluorescence emission of significantly higher intensity than the other parts.

[0035] As can be seen from the examples of Fig. As is clear from Figures 11A to 12D, the structural defects of the injection-molded syringe, like the PET plastic bottle example, can also be clearly detected by capturing the image of the fluorescence wavelength range. Likewise, regardless of the plastic material and molding method of the plastic molded article, for molding defects with increased wall thickness or molding defects with increased density and crystallization of the plastic, it is possible to detect the presence of these molding defects based on the fluorescent light intensity in the image.

[0036] In one aspect of the present invention, the inspectable condition of the plastic molded article is not limited to the presence of molding defects. By using the correspondence relationship between the intensity of the inspection object light emitted when a plastic molded article is irradiated with an excitation light such as UV light and the condition with respect to at least one of the shape and structure of the plastic molded article as a guide, various conditions can be inspected in the same manner as in the above embodiment. For example, on plastic molded articles such as bottles or the like, a marking portion displaying various information such as text, numbers, and symbols is sometimes formed.By changing the shape or structure of the plastic molded article, the marking portion shares common elements with molding defects such as the above-mentioned defects involving wall thickness and structural defects. Molding defects in plastic molded articles are caused by changes in the shape of the plastic molded article from its original shape, such as wall thickness, or by changes in the plastic molded article itself from its original structure, such as stress whitening or yellowing. In contrast, marking portions can be formed by transferring uneven shapes on the mold to the plastic molded article, or by a laser marking process that locally carbonizes, melts, or foams the plastic to change its structure.In marking sections formed in these procedures, the intensity of the test object light changes compared to the surroundings of the marking section, so that it can be detected based on this change.

[0037] Fig. 13 shows an example of an image taken by the test device 1 Fig. 1 of the marking section on and around the shoulder section of a bottle, the bottle being illuminated with UV light and the image being taken in the wavelength range of the excited fluorescence emission. It is an example of an image taken when the same bottle was illuminated with visible light in the wavelength range of the illuminating light. A comparison of these images shows that in the image from Fig. 13 in the area X7 the marking section appears as a part with high brightness and there is a brightness difference between the marking section and its surroundings. The marking section of Fig. 13 was formed by laser marking, whereby the melting and foaming of the plastic at the laser-marked area of the bottle results in a change in the microstructure and crystal structure. As a result of this structural change, the intensity of the fluorescence emission increases compared to the surroundings of the marked section, so that the brightness difference is also likely to increase. The marked section of Fig. 13 is formed from a combination of letters, numbers, and symbols used, for example, for bottle traceability. However, part of the marking section is masked because it depicts an actual bottle in circulation. The brightness of the masked part is the same as other parts of the marking section.

[0038] Fig. Fig. 15 shows an example of an image obtained from a marking portion formed on a neck portion of a bottle and its surroundings with the inspection apparatus 1. Fig. 1. The marking section from Fig. 15 is formed by transferring an uneven shape formed in the mold to the neck portion during molding of the preform, and can be understood as an example of a location where the shape of the marking portion deviates from the shape of its surroundings. The wall thickness of the marking portion is the same as that of its surroundings. However, the wall thickness of the marking portion may also deviate from that of its surroundings. A structural change such as increased density may also occur at at least a part of the marking portion due to excessive stretching of the plastic or the like. In the image from Fig. 15, in the X8 region, the marking section, and especially its edge portion, appears as a highly bright part, and there is a brightness difference between the marking section and its surroundings. If the wall thickness of the marking section changes more than its surroundings, or if a structural change similar to stress whitening occurs, the fluorescent light intensity of the marking section increases, just as with defects with different wall thickness and structural defects, so the brightness difference between the marking section and its surroundings is likely to increase even further.

[0039] From the picture of Fig. 13 it can be seen that a location of the bottle with a changed microstructure or crystal structure can be detected with the inspection method of the above embodiment, and from the image of Fig.From FIG. 15, it can be seen that a location of the bottle with a changed shape can be detected using the inspection method of the above embodiment. When inspecting the marking portion, for example, based on the fluorescent light intensity of the acquired image, the location showing the fluorescent light intensity that should be observed at the marking portion can be detected, and based on this detection result, an inspection of the marking portion is possible. Various points regarding the marking portion can be used as the inspection item, such as whether the marking portion is formed in the correct shape, whether the position of the marking portion is correct, or whether the information displayed on the marking portion is correct.

[0040] The inspection of the shape and structure of a molded plastic article can be performed in parallel or sequentially at multiple inspection points. For example, the presence of molding defects and the accuracy of the marking section can be inspected in parallel or sequentially using the same image. Performing such complex inspections using the same inspection fixture has the advantage of reducing the inspection time and reducing the load on the equipment required for the inspection.

[0041] In the above embodiment, the image pickup device 12 including the camera 13 was used as the image pickup device, but it is not limited to an example in which the image pickup device uses a camera. In the inspection of the present invention, as long as data indicating a signal intensity corresponding to the intensity of the inspection object light in the inspection area of the plastic molded article can be obtained, the presence of molding defects can be inspected based on the intensity of the inspection object light indicated by the data. Therefore, data reflecting the intensity of the inspection object light can be obtained using various sensors that output detection signals corresponding to the intensity of the inspection object light, and the presence of molding defects can be inspected based on the intensity of the inspection object light in the acquired data.For example, data on the intensity distribution of the inspection object light in the inspection area can be obtained using an intensity sensor with a flat two-dimensional sensing area. Or, data on the intensity distribution of the inspection object light in the inspection area can be obtained by scanning the inspection area with a one-dimensional light intensity sensor (line scanner). Since the data thus obtained has a signal strength corresponding to the intensity distribution of the inspection object light, it is substantially equivalent to image data acquired at the camera 13. Therefore, this type of data is also included in the term "image" in the present invention, and detection devices that use various sensors to detect this type of data are included in the term "image pickup device" in the present invention.

[0042] Various aspects of the invention resulting from the above embodiment and its modifications will be described below. To facilitate understanding of the individual aspects of the invention, the corresponding components shown in the accompanying drawings are labeled with parentheses in the following description, but this does not limit the invention to the illustrated embodiment.

[0043] An inspection method for plastic molded articles according to one aspect of the present invention is an inspection method for inspecting plastic molded articles (2), comprising the steps of: illuminating an inspection area of a plastic molded article with excitation light capable of being radiated from the plastic molded article with inspection object light having a wavelength range different from that of the radiated light, capturing the inspection area of the plastic molded article illuminated with the excitation light such that the wavelength range of the inspection object light is included in the wavelength range of the image object while the wavelength range of the excitation light is excluded from the wavelength range of the image object, and inspecting the presence of molding defects in the inspection area based on an intensity of the inspection object light in the captured image.

[0044] An inspection device for plastic molded articles according to one aspect of the present invention is an inspection device (1) for inspecting plastic molded articles (2) for molding defects, comprising: means (11) for illuminating an inspection area of a plastic molded article by excitation light that can be emitted from the plastic molded article with inspection object light having a wavelength range different from that of the emitted light; means (12) for recording the inspection area of the plastic molded article illuminated with the excitation light such that the wavelength range of the inspection object light is included in the wavelength range of the recording object, while the wavelength range of the excitation light is excluded from the wavelength range of the recording object;and means (22) for inspecting a condition relating to at least one of the shape and the structure of the plastic molded article in the inspection area based on an intensity of the inspection object light in the captured image.

[0045] If there is a change in at least one of the shape and structure of the plastic molded article by a molding defect occurring in which, for example, the wall thickness of the plastic molded article locally increases compared to the normal value or the molecular chains of the plastic orient and condense so that crystallization occurs and the plastic structure is locally modified, or if the shape or structure of the plastic molded article is deliberately changed, the intensity of the test object light emitted from this point is different from that in the case where no such change occurs.Therefore, by imaging the inspection area of the plastic molded article illuminated with excitation light in such a way that the wavelength range of the imaging object is determined as described above, the quality of at least one of the shape and structure of the plastic molded article can be inspected based on the intensity of the inspection object light in the obtained image. Since the quality of the plastic molded article can be inspected using image processing, an efficient inspection with high accuracy can be performed compared to relying on visual inspection.

[0046] With the above inspection step or the above inspection device, the presence of molding defects can be inspected with respect to at least one of the shape and structure of the plastic molded article as the condition of the plastic molded article. Accordingly, the presence of molding defects can be inspected with high efficiency and accuracy.

[0047] In the above aspects, UV light is an example of the excitation light, and the inspection light may be fluorescence occurring on the plastic molded article. In the above inspection step, the presence of molding defects can be inspected by judging whether there is a location in an image having an intensity that deviates from the range of the intensity of the inspection light in the case of the absence of molding defects. The inspection device can also inspect in the same way. In this case, by checking whether there is a location in the image where the intensity of the inspection light deviates due to a molding defect, molding defects can be detected with high efficiency and accuracy.

[0048] In the above inspection step and the above inspection device, the presence of molding defects can be inspected by judging whether there is a location in the image where the intensity of the inspection object light deviates from that which should be observed due to the occurrence of a molding defect due to a deviation in the wall thickness of the plastic molded article or a change in the crystal structure of the plastic. The inspection device can also inspect in the same way. In this case, a location with a molding defect due to a deviation in the wall thickness or a change in the crystal structure can be detected based on the intensity of the inspection object light in the image.

[0049] With the above inspection step or device, a marking portion formed by changing at least one of the shape and structure of the plastic molded article as the nature of the plastic molded article can be inspected. Furthermore, with the above inspection step or device, a location with an intensity of the inspection object light that should be observed on the plastic molded article where the marking portion exists can be detected, and the marking portion can be detected based on the detection result. Thus, the suitability of the marking portion can be inspected based on the fluorescent light intensity in the image.

[0050] In the above aspect, the plastic molded article may be formed by blow molding or injection molding. Therefore, according to the present invention, molding defects in a plastic molded article formed by blow molding or injection molding can be inspected with high efficiency and accuracy. Explanation of reference symbols 1 test device 2 bottles (plastic molded article) 11 Lighting device (lighting equipment) 12 Image recording device (image recording device) 13 Camera 14 filters 20 processing units 22 Test unit (test facility) D1, D2 section with different wall thickness D3 core deviation section D4 White QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] JP 2008-281477 A

[0002] JP 2022-37644 A

[0002]

Claims

[1] Test method for testing plastic moulded articles, comprising the following steps: Illuminating a test area of a plastic molded article by excitation light that can be emitted from the plastic molded article with test object light having a wavelength range that differs from that of the emitted light, Recording the test area of the plastic molded article illuminated with the excitation light such that the wavelength range of the test object light is included in the wavelength range of the recording object, while the wavelength range of the excitation light is excluded from the wavelength range of the recording object, and Inspecting a condition with respect to at least one of the shape and the structure of the plastic molded article in the inspection area based on an intensity of the inspection object light in the captured image. [2] The inspection method for inspecting plastic molded articles according to claim 1, wherein in the inspection step, the presence of molding defects is inspected with respect to at least one of the shape and the structure of the plastic molded article as the condition of the plastic molded article. [3] An inspection method for inspecting plastic molded articles according to claim 2, wherein in the inspection step, the presence of molding defects is inspected by judging whether there is a spot in the image having an intensity different from the range of intensity of the inspection object light in the case of the absence of molding defects. [4] An inspection method for inspecting plastic molded articles according to claim 2, wherein in the inspection step, the presence of molding defects is inspected by judging whether there is a position in the image where the intensity of the inspection object light deviates from that which should be observed due to the occurrence of a molding defect due to a deviation in the wall thickness of the plastic molded article or a change in the crystal structure of the plastic. [5] The inspection method for inspecting plastic molded articles according to claim 1, wherein in the inspection step, a marking portion formed by changing at least one of the shape and the structure of the plastic molded article as the constitution of the plastic molded article is inspected. [6] The inspection method for inspecting plastic molded articles according to claim 5, wherein in the inspection step, a position having an intensity of the inspection object light which should be observed on the plastic molded article where the marking portion is present is detected, and the marking portion is detected based on the detection result. [7] Testing device for testing plastic molded articles, comprising: a device for illuminating an inspection area of a plastic molded article by excitation light that can be emitted from the plastic molded article, with inspection object light having a wavelength range different from that of the emitted light, a device for recording the test area of the plastic molded article illuminated with the excitation light such that the wavelength range of the test object light is included in the wavelength range of the recording object, while the wavelength range of the excitation light is excluded from the wavelength range of the recording object, and means for inspecting a condition with respect to at least one of the shape and the structure of the plastic molded article in the inspection area based on an intensity of the inspection object light in the captured image. [8] An inspection apparatus for inspecting plastic molded articles according to claim 7, wherein said inspection means inspects the presence of molding defects with respect to at least one of the shape and the structure of the plastic molded article as the condition of the plastic molded article. [9] An inspection apparatus for inspecting plastic molded articles according to claim 8, wherein said inspection means inspects the presence of molding defects by judging whether there is a spot in the image having an intensity different from the range of intensity of the inspection object light in the case of the absence of molding defects. [10] An inspection apparatus for inspecting plastic molded articles according to claim 8, wherein the inspection means inspects the presence of molding defects by judging whether there is a position in the image where the intensity of the inspection object light deviates from that which should be observed due to the occurrence of a molding defect due to a deviation in the wall thickness of the plastic molded article or a change in the crystal structure of the plastic. [11] The inspection apparatus for inspecting plastic molded articles according to claim 1, wherein the inspection means inspects a marking portion formed by changing at least one of the shape and the structure of the plastic molded article as the condition of the plastic molded article. [12] The inspection apparatus for inspecting plastic molded articles according to claim 11, wherein the inspection means detects a position with an intensity of the inspection object light that should be observed on the plastic molded article where the marking portion exists, and detects the marking portion based on the detection result.

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