Apparatus and method for inspecting containers

Abstract

The invention relates to an apparatus (1) for inspecting containers (3), which apparatus comprises an illumination device (27), a rotary device (25) and an image-capturing device (29). The illumination device (27) is designed to illuminate an illumination region (37) alternatingly using different illumination patterns which comprise at least a first illumination pattern (43) and a second illumination pattern (47). The illumination device (27) is designed to illuminate the illumination region (37) in first time windows (41) using the first illumination pattern (43) and to illuminate same in second time windows (45) using the second illumination pattern (47). The rotary device (25) is designed to rotate a container (3) having a bottom (5) and a side wall (7) about an axis (35) of the container (3) in such a way that at least a portion of the side wall (7) passes through the illumination region (37) in a direction of rotation (36). The image-capturing device (29) is designed to capture an image of the illumination region (37) at least in each first time window (41) and in each second time window (45).

Description

[0001] Device and method for inspecting vessels

[0002] The invention relates to the inspection of vessels, in particular the inspection of transparent or translucent vessels.

[0003] EP 2 434 276 B1 discloses an inspection method for checking transparent or translucent containers for defects such as cracks, fissures, bubbles, or the like. The containers are continuously conveyed by a conveyor device along a conveying direction. Each container passes through an inspection station in which a non-contact inspection of at least a selected container region of each container takes place. The container is temporarily raised or lowered essentially perpendicular to the conveying direction. While a container is being raised or lowered, the selected container region is irradiated by at least two radiation sources arranged on opposite sides of the container. The radiation reflected by the raised or lowered container is recorded by at least one recording device with a sensor unit assigned to each radiation source.To prevent, for example, opposing radiation sources from negatively influencing each other when detecting a defect, a sequential all-round scan is carried out.

[0004] The system of EP 2 434 276 B1 is comparatively complex and requires a large number of components.

[0005] The object of the invention is to provide a way in which vessels can be inspected with the least possible effort and yet with high inspection quality.

[0006] This object is achieved by the device according to claim 1 and the method according to claim 12, respectively. The dependent claims specify advantageous embodiments of the invention.

[0007] According to one aspect of the invention, a device for inspecting vessels is provided. The device comprises an illumination device, a rotating device, and a receiving device. The illumination device is configured to alternately illuminate an illumination region with different illumination patterns. The different illumination patterns comprise at least a first illumination pattern and a second illumination pattern. The illumination device is configured to illuminate the illumination region with the first illumination pattern in first time windows and with the second illumination pattern in second time windows. The rotating device is configured to rotate a vessel having a bottom and a side wall about an axis of the vessel such that at least a portion of the side wall passes through the illumination region along a direction of rotation.The recording device is configured to take a picture of the illumination area at least in every first time window and in every second time window.

[0008] Since the section of the vessel's side wall passes through the illumination area along the direction of rotation, a region of the side wall within the illumination area can be inspected that has a greater extension along the direction of rotation than the extension of the illumination area along the direction of rotation. In particular, a region of the side wall that extends around the entire circumference of the vessel can be inspected within the illumination area. It is not necessary to arrange inspection units on different sides of the vessel.

[0009] Due to the illumination of the lighting area by the lighting device, defects and imperfections in the side wall can be more easily identified compared to an unlit state.

[0010] Depending on the illumination pattern used to illuminate the sidewall in the illumination area, different types of imperfections or defects in the sidewall may be visible to varying degrees. In the first time windows, in which the illumination area is illuminated with the first illumination pattern, a different type of imperfection or defect may be particularly clearly visible in an area of ​​the sidewall located within the illumination area than in the second time windows, in which the illumination area is illuminated with the second illumination pattern.

[0011] Since the recording device takes a picture of the illumination area in every first time window and in every second time window, both pictures are obtained in which the side wall is illuminated with the first illumination pattern and pictures are obtained in which the side wall is illuminated with the second illumination pattern.

[0012] Due to the alternation between at least the first illumination pattern and the second illumination pattern, one image can be taken with the first illumination pattern and one image with the second illumination pattern when the vessel is rotated further by a certain angle. The frequency of alternation between the first illumination pattern and the second illumination pattern can be suitably adapted to the rotation speed of the vessel in order to achieve a desired resolution along the circumference of the side wall.The frequency of the alternation between at least the first illumination pattern and the second illumination pattern can be suitably adjusted to the rotational speed of the vessel in order to completely cover a region of the side wall extending around the entire circumference of the vessel with images taken with the first illumination pattern and with images taken with the second illumination pattern over the course of one full rotation of the vessel. A region of the side wall of the vessel extending around the entire circumference of the vessel can be completely inspected with the first illumination pattern and with the second illumination pattern within one rotation.

[0013] Since the illumination with the first illumination pattern and the illumination with the second illumination pattern, as well as the corresponding images, occur in the same illumination area, a viewing window onto the vessel can be essentially fully utilized both for images taken with the first illumination pattern and for images taken with the second illumination pattern. A viewing window onto the vessel may be limited, for example, by devices for transporting the vessel, by neighboring vessels, or by other machine elements.

[0014] Since the illumination with the first illumination pattern and the illumination with the second illumination pattern as well as the corresponding recordings are carried out one after the other, mutual interference of the different illumination patterns can be reduced or avoided.

[0015] The side wall of the vessel can be transparent or translucent. The side wall of the vessel can comprise or be made of glass. The side wall of the vessel can, for example, comprise or be made of white glass, amber glass, green glass, blue glass, red glass, or other colored glass, particularly in the visible spectrum. The side wall can comprise or be made of black glass. Black glass refers to glass that is opaque in the visible wavelength range but can allow a certain degree of transmission in the NIR (near-infrared) range, particularly in the range between 760 nanometers and 2500 nanometers.

[0016] The axis of the vessel may be perpendicular to the bottom of the vessel. The axis of the vessel may extend along a direction parallel to the direction in which the side wall extends away from the bottom. During rotation by the rotating device, the vessel may stand on a horizontal plane. During rotation by the rotating device, the vessel, in particular the bottom of the vessel, may stand on a horizontal surface. During rotation by the rotating device, the axis of the vessel may extend along a vertical direction. The direction of rotation may correspond to a circumferential direction of the side wall.

[0017] The container can be designed as a bottle, in particular a glass bottle. The container can be designed as a preserving jar or as a non-circular container. The container can be designed as a packaging jar.

[0018] Preferably, the illumination device is configured to periodically illuminate the illumination area alternately with the different illumination patterns. A periodic illumination sequence can simplify synchronization between the illumination device and the recording device.

[0019] The different illumination patterns may comprise only the first illumination pattern and the second illumination pattern. The different illumination patterns may contain one or more additional illumination patterns, in particular at least one third illumination pattern.

[0020] Preferably, a second time window directly follows a preceding first time window. Preferably, a first time window directly follows a preceding second time window. If the illumination with the first illumination pattern and the illumination with the second illumination pattern directly follow one another, the vessel can be inspected comparatively quickly, so that a high throughput of vessels can be achieved. A time span between illuminating the illumination area with the first illumination pattern and subsequently illuminating the illumination area with the second illumination pattern can be less than 200 microseconds, or less than 150 microseconds, or less than 100 microseconds, or less than 50 microseconds, or less than 30 microseconds, or less than 20 microseconds.A time period between illuminating the illumination area with the second illumination pattern and subsequently illuminating the illumination area with the first illumination pattern may be less than 200 microseconds, or less than 150 microseconds, or less than 100 microseconds, or less than 50 microseconds, or less than 30 microseconds, or less than 20 microseconds.

[0021] There may be a time interval between a first time window and a subsequent second time window. There may be a time interval between a second time window and a subsequent first time window. In particular, at least one third time window may lie between a first time window and a subsequent second time window or between a second time window and a subsequent first time window. In the third time window, the illumination region may be unlit or illuminated with a third illumination pattern. The recording device may be configured to take a picture of the illumination region in the third time window.

[0022] In the first time windows, the illumination area can be continuously illuminated with the first illumination pattern. In the second time window, the illumination area can be continuously illuminated with the second illumination pattern. The first time window can have a time duration of less than 200 microseconds, or a time duration of less than 100 microseconds, or a time duration of less than 50 microseconds, or a time duration of less than 20 microseconds. The second time window can have a time duration of less than 200 microseconds, or a time duration of less than 100 microseconds, or a time duration of less than 50 microseconds, or a time duration of less than 20 microseconds. The first time window can have a time duration of more than 10 microseconds, or more than 50 microseconds. The second time window can have a time duration of more than 10 microseconds, or more than 50 microseconds.All first time windows can have the same duration. All second time windows can have the same duration. A duration of the first time window and a duration of the second time window can be at least substantially identical, for example, up to a maximum of 20 percent, or up to a maximum of 10 percent, or up to a maximum of 5 percent of the larger time window.

[0023] The rotating device can be configured to rotate the vessel continuously, in particular at a constant angular velocity. The rotating device can be configured to rotate the vessel intermittently.

[0024] The first illumination pattern can correspond to an at least substantially uniform illumination of the illumination region. An at least substantially uniform illumination of the illumination region can facilitate the detection of opaque defects or voids in the sidewall. An at least substantially uniform illumination of the illumination region can facilitate the detection of non-transparent voids, such as inclusions. An at least substantially uniform illumination of the illumination region can facilitate the detection of stress voids or stress defects in the sidewall. The second illumination pattern can correspond to the illumination of different subregions of the illumination region with different light intensities. In particular, subregions with different light intensities can spatially alternate.When illuminated with the second illumination pattern, certain sub-areas of the illuminated area can be illuminated with a first, higher intensity, while at the same time certain other sub-areas of the illuminated area can be illuminated with a second, lower light intensity. The second illumination pattern can have a higher contrast than the first illumination pattern. Illuminating different sub-areas of the illuminated area with different light intensities can facilitate the detection of transparent imperfections or defects in the sidewall, for example, those with varying wall thicknesses but little or no contrast-generating properties. The second illumination pattern can, for example, facilitate the detection of thin spots or shallow bubbles in the sidewall.

[0025] The lighting device can be configured to illuminate the illumination area in a striped pattern when illuminating the illumination area with the second illumination pattern. In the striped pattern, stripes of lower light intensity can alternate with stripes of higher light intensity. For example, at least 10, or at least 15, or at least 20, or at least 25, or at least 30 stripes can be provided. The stripes can run parallel to one another. The stripes can be configured as horizontal stripes. The stripes can be configured as vertical stripes. The striped pattern can facilitate the detection of transparent imperfections or defects in the sidewall.

[0026] The lighting device can be configured to illuminate the illuminated area in a checkered pattern or a checkerboard pattern when illuminating the illuminated area with the second illumination pattern. Within the checkered pattern or checkerboard pattern, fields of lower light intensity can alternate with fields of higher light intensity. A checkered pattern or checkerboard pattern can achieve particularly high-contrast illumination of the illuminated area, which can facilitate the detection of transparent imperfections or defects in the sidewall.

[0027] The first illumination pattern may be configured to make a first type of defect in the sidewall detectable. The second illumination pattern may be configured to make a second type of defect in the sidewall detectable. The first illumination pattern may be configured to facilitate detection of a first type of defect in the sidewall. The second illumination pattern may be configured to facilitate detection of a second type of defect in the sidewall. The first type of defect may include, for example, opaque defects and / or stress defects. The second type of defect may include, for example, transparent defects.

[0028] The device may comprise a computing unit. The computing unit may be configured to combine the images acquired during the rotation of the vessel in the first time windows into a first image. The computing unit may be configured to combine the images acquired during the rotation of the vessel in the second time windows into a second image. The combined image may depict a region of the side wall of the vessel that extends around a full circumference of the side wall. The combined image may represent, in a sense, an unrolled view of the region of the side wall. The combined images may facilitate analysis of the images to detect defects or imperfections in the side wall.

[0029] The computing unit may be configured to analyze the composite images to detect imperfections or defects in the sidewall, in particular by means of an image analysis algorithm.

[0030] The illumination device can comprise light sources. The illumination device can comprise a plurality of light sources, for example at least 50 light sources, or at least 100 light sources, or at least 500 light sources, or at least 1000 light sources, or at least 1250 light sources. In particular, the illumination device can have, for example, 1218 light sources. The light sources can be designed as LEDs, for example. The light sources can be identical light sources. The light sources can be configured to illuminate the illumination area with light in the visible wavelength range. The LEDs can be configured to illuminate the illumination area with NIR light (near-infrared light). The NIR light can, for example, have wavelengths in the range between 760 nanometers and 2500 nanometers. The use of NIR light can be particularly advantageous when examining black glass.

[0031] The illumination device may include a polarization filter. The illumination device may be configured to illuminate the illumination area through the polarization filter. The polarization filter may be a linear polarization filter. The polarization filter may be configured to allow light of a specific linear polarization to pass through, in particular to allow only light of a specific linear polarization to pass through. Illumination through a polarization filter may facilitate the detection of stress defects or stress omissions in the sidewall.

[0032] The lighting device may comprise light sources that participate in both illuminating the illumination area with the first illumination pattern in the first time windows and illuminating the illumination area with the second illumination pattern in the second time windows. Using light sources for both the first illumination pattern and the second illumination pattern can reduce the total number of light sources required.

[0033] The lighting device can be configured to periodically change the brightness of at least one light source of the lighting device. By periodically changing the brightness of the at least one light source, a change between the first lighting pattern and the second lighting pattern can be achieved.

[0034] The brightness of the at least one light source can be changed by current control. The brightness of the at least one light source can be changed by voltage control. The brightness of the at least one light source can be changed by pulse width modulation. By controlling the at least one light source by pulse width modulation, a particularly high-frequency brightness change can be achieved, in particular compared to completely switching selected light sources on and off. The pulse width modulation can extend over the entire duration of the first illumination pattern and over the entire duration of the second illumination pattern in order to avoid creating dark spots over time.

[0035] The lighting unit can be configured such that each light source emits a temporally constant luminous flux, i.e., has a temporally constant brightness, over the entire duration of the first lighting pattern. The lighting unit can be configured such that each light source emits a temporally constant luminous flux, i.e., has a temporally constant brightness, over the entire duration of the second lighting pattern.

[0036] The lighting device can comprise multiple groups of light sources. The lighting device can be configured to control the light sources of all groups of light sources to emit the same luminous flux when illuminating the illumination area with the first illumination pattern. The lighting device can be configured to control the light sources of certain groups of light sources to emit a different luminous flux than the light sources of certain other groups of light sources when illuminating the illumination area with the second illumination pattern. The groups of light sources can each correspond to a stripe of a stripe pattern with which the illumination area is illuminated when illuminated with the second illumination pattern.

[0037] The illumination device may comprise an area array of light sources. The light sources may be arranged in a plane. Preferably, the distance between adjacent light sources is no more than 10 millimeters, or no more than 7 millimeters, or no more than 5 millimeters, or no more than 4.5 millimeters.

[0038] The first time windows and the second time windows may alternate at a frequency of at least 15 kilohertz, or at least 20 kilohertz, or at least 25 kilohertz, or at least 30 kilohertz, or at least 35 kilohertz, or at least 40 kilohertz, or at least 45 kilohertz, or at least 50 kilohertz.

[0039] The different illumination patterns may alternate at a frequency of at least 15 kilohertz, or at least 20 kilohertz, or at least 25 kilohertz, or at least 30 kilohertz, or at least 35 kilohertz, or at least 40 kilohertz, or at least 45 kilohertz, or at least 50 kilohertz.

[0040] The recording device can comprise a first recording unit. The first recording unit can be configured to take a picture of the illumination area in every first time window. The first recording unit can also be configured to take a picture of the illumination area in every second time window. The first recording unit can be configured to take at least one picture of the illumination area while the illumination area is alternately illuminated with the different illumination patterns. The first recording unit can be designed without a polarization filter, i.e., can be configured to record light from the recording area without passing through a polarization filter.

[0041] According to one embodiment, the first recording unit can be provided as the sole recording unit of the recording device. Alternatively, the recording device can comprise one or more further recording units. In particular, the recording device can comprise a second recording unit. The second recording unit can be configured to take a picture of the illumination area in each first time window. The second recording unit can comprise a polarization filter. The second recording unit can be configured to take a picture of the illumination area through the polarization filter in each first time window. The polarization filter can be a linear polarization filter. The polarization filter can be rotated by 90 degrees relative to a polarizing filter of the illumination device. Due to the crossed polarizing filters, the resulting image can be virtually black.Stress-generating defects in the sidewall that rotate the plane of polarization of the light may be brightly visible in the image.

[0042] The first recording unit and the second recording unit can each record the illumination area through a separate optical system. The first recording unit and the second recording unit can record the illumination area through the same optical system, thus sharing the optical system. The optical system can be designed as a telecentric optical system.

[0043] If the first recording unit and the second recording unit are provided, two images can be generated in each first time window, one by the first recording unit and one by the second recording unit. Due to different properties of the first recording unit and the second recording unit, different images can be obtained in which different types of imperfections or defects in the sidewall are visible. For example, opaque defects or imperfections can be particularly clearly visible in images recorded by the first recording unit without a polarization filter. Stress-based defects or imperfections can be particularly clearly visible in images recorded by the second recording unit with a polarization filter.

[0044] A third recording unit could also be provided, configured to take a picture of the illumination area every other time window. If a third recording unit is provided, it is possible, but not mandatory, for the first recording unit to also take a picture of the illumination area every other time window.

[0045] The terms “first recording unit,” “second recording unit,” and “third recording unit” are used to facilitate reference to the recording units, but do not represent a limitation. For example, the presence of the third recording unit does not necessarily require that a second recording unit is also present. In particular, only the first recording unit could be provided, or only the first recording unit and the second recording unit could be provided, or only the first recording unit and the third recording unit could be provided, or the first recording unit, the second recording unit, and the third recording unit could be provided. The first recording unit, the second recording unit, and / or the third recording unit can be designed as a camera, in particular as a line scan camera or as a matrix camera.

[0046] The first receiving unit, the second receiving unit and / or the third receiving unit can be designed to receive black glass.

[0047] The illumination device and the recording device can be provided on opposite sides of the illumination area. The illumination area can be located between the illumination device and the recording device. The vessel can be rotated about the vessel's axis between the illumination device and the recording device. The recording device can be configured to take images using the transmitted-light method.

[0048] The device may comprise a transport device for transporting the vessels along a transport direction. The transport device may be configured to transport the vessels to the illumination area and, after the vessels have been inspected, to transport the vessels away from the illumination area. The transport device may be configured to move the vessels along a circular path. The transport device may be designed as a star wheel. The transport device may be configured to move the vessels along a linear transport path.

[0049] The illumination device, the rotating device, and the receiving device can together form an inspection station. The inspection station can be referred to as the first inspection station. The first inspection station can, as described, be designed to inspect the section of the side wall of the vessel that passes through the illumination region. The device can comprise at least one further inspection station, in particular a second inspection station, which can also have an illumination device, a rotating device, and a receiving device. The vessel can be inspected successively in the inspection stations. The second inspection station can be designed analogously to the first inspection station, except for a different position of the illumination region with respect to the vessel. In the second inspection station, a different section of the side wall of the vessel can pass through an illumination region and be inspected.Thus, by arranging several inspection stations one after the other, a larger section of the side wall or preferably the entire side wall can be inspected.

[0050] According to a further aspect of the invention, a method for inspecting vessels is provided. A vessel having a bottom and a side wall is rotated about an axis of the vessel such that at least a portion of the side wall passes through an illumination region along a direction of rotation. The illumination region is alternately illuminated with different illumination patterns. The different illumination patterns comprise at least a first illumination pattern and a second illumination pattern. The illumination region is illuminated with the first illumination pattern in first time windows and with the second illumination pattern in second time windows. An image of the illumination region is taken at least in every first time window and in every second time window.

[0051] Depending on the illumination pattern used to illuminate the sidewall in the illumination area, different types of imperfections or defects in the sidewall may be visible to varying degrees. In the first time windows, in which the illumination area is illuminated with the first illumination pattern, a different type of imperfection or defect may be particularly clearly visible in an area of ​​the sidewall located within the illumination area than in the second time windows, in which the illumination area is illuminated with the second illumination pattern.

[0052] The first illumination pattern can correspond to an at least substantially uniform illumination of the illumination region. An at least substantially uniform illumination of the illumination region can facilitate the detection of opaque defects or voids in the sidewall. An at least substantially uniform illumination of the illumination region can facilitate the detection of non-transparent voids, such as inclusions. An at least substantially uniform illumination of the illumination region can facilitate the detection of stress voids or stress defects in the sidewall. The second illumination pattern can correspond to the illumination of different subregions of the illumination region with different light intensities. In particular, subregions with different light intensities can spatially alternate.When illuminated with the second illumination pattern, certain sub-areas of the illuminated area can be illuminated with a first, higher intensity, while at the same time certain other sub-areas of the illuminated area can be illuminated with a second, lower light intensity. The second illumination pattern can have a higher contrast than the first illumination pattern. Illuminating different sub-areas of the illuminated area with different light intensities can facilitate the detection of transparent imperfections or defects in the sidewall, for example, those with varying wall thicknesses but little or no contrast-generating properties. The second illumination pattern can, for example, facilitate the detection of thin spots or shallow bubbles in the sidewall.

[0053] The images taken in the first time windows can be combined to form a first image. The images taken in the second time windows can be combined to form a second image. A further image of the illuminated area can be taken in each first time window, with the further image preferably being taken through a polarization filter.

[0054] To switch from the first illumination pattern to the second illumination pattern, a plurality of light sources can be controlled by means of pulse width modulation so that the luminous flux emitted by the light sources is changed.

[0055] As described, the invention comprises a device for inspecting vessels and a method for inspecting vessels. Features, explanations, and descriptions described with reference to the device can be transferred to the method. Features, explanations, and descriptions described with reference to the method can be transferred to the device. The device can be suitable, designed, and / or configured to carry out the method. The method can be carried out using the device or can be carried out using the device. The method step of rotating the vessel can be carried out by the rotating device described with reference to the device. The method step of illuminating the illumination region can be carried out by the illumination device described with reference to the device.The method step of creating a recording of the illumination area in each first time window and in each second time window can be carried out by the recording device described with regard to the device.

[0056] In the following, the invention is further described using embodiments with reference to the figures.

[0057] Fig. 1 shows a schematic plan view of a device for inspecting vessels according to an embodiment.

[0058] Fig. 2A shows a schematic partial side view of the device in the direction of view from the illumination device of the first inspection station to a vessel inspected in the first inspection station according to the embodiment.

[0059] Fig. 2B shows a schematic partial side view of the device in the direction of view from the illumination device of the second inspection station to a vessel inspected in the second inspection station according to the embodiment.

[0060] Fig. 3A shows a schematic partial sectional view through the device in the region of the first inspection station according to the embodiment, wherein the sectional plane is a vertical plane which is parallel to a radial direction with respect to the star wheel.

[0061] Fig. 3B shows a schematic partial sectional view through the device in the region of the second inspection station according to the embodiment, wherein the sectional plane is a vertical plane parallel to a radial direction relative to the star wheel. Fig. 4 shows a schematic view of the illumination device of an inspection station in the direction of view from a vessel inspected in the inspection station to the illumination device according to the embodiment.

[0062] Fig. 5 shows a schematic representation of the temporal sequence of the illumination of the illumination areas according to one embodiment.

[0063] Fig. 6 shows a schematic representation of the process of inspecting the vessel with the device according to an embodiment.

[0064] Fig. 7A shows a schematic representation of a first image composed of individual images according to one embodiment.

[0065] Fig. 7B shows a schematic representation of a second image composed of individual images according to one embodiment.

[0066] Fig. 70 shows a schematic representation of a third image composed of individual images according to an embodiment.

[0067] Fig. 8 shows a schematic representation of a lighting device of the device according to an embodiment.

[0068] Figure 1 shows a schematic top view of a device 1 for inspecting containers 3 according to one embodiment. As shown in Figures 2A and 2B, the containers 3 are bottles with a bottom 5 and a side wall 7. Alternatively, the containers 3 can be, for example, jars or other types of packaging glass.

[0069] As shown in Figure 1, the device 1 comprises a transport device 9 for transporting the containers 3 along a transport direction 11. In the illustrated embodiment, the transport device 9 has a star wheel 13 which transports the containers 3 along a circular path. The star wheel 13 comprises holding elements 15 which are arranged one behind the other along a circumferential direction of the star wheel 13. The containers 3 are transferred from a transfer station 17 to the star wheel 13 by being placed between adjacent holding elements 15 of the star wheel 13. By rotating the star wheel 13, the containers 3 are conveyed along the transport direction 11. During conveyance, the containers 3 are pushed by the holding elements 15 of the star wheel 13 over a transport surface 19 of the transport device 9. The transport of the containers 3 along the transport direction 11 takes place in a clocked manner.After the vessels 3 have been inspected in the device 1, they are removed from the transport device 9 by a removal station 21 located downstream of the transfer station 17 with respect to the transport direction 11. With respect to the transport direction 11, between the transfer station 17 and the removal station 21, a first inspection station 23 and a second inspection station 24 are provided one after the other, at which the side wall 7 of the vessels 3 is examined for imperfections or defects. During the inspection of a vessel 3 by the inspection stations 23, 24, the star wheel 13 is preferably stationary. Therefore, preferably, no transport of the vessel 3 along the transport direction 11 takes place during this time.

[0070] During the inspection of the vessel 3 in an inspection station 23, 24, the vessel 3 is in contact with a rotating device 25 of the inspection station 23, 24. In the illustrated embodiment, the rotating device 25 is in contact with the side wall 7 to rotate the vessel 3. Alternatively, the rotating device 25 can be embedded in the transport surface 19 as a turntable, and the vessel 3 can rest on the rotating device 25 during the inspection of the vessel 3. The inspection stations 23, 24 each comprise an illumination device 27 and a receiving device 29. In the illustrated embodiment, the receiving device 29 comprises a first receiving unit 31 and a second receiving unit 33. Figure 2A shows a schematic side view of a vessel 3 inspected by the first inspection station 23 in the direction of view from the illumination device 27 of the first inspection station 23 onto the vessel 3.During inspection, the vessel 3 is rotated by the rotating device 25 of the first inspection station 23 about an axis 35 of the vessel 3 along a direction of rotation 36. In the illustrated embodiment, axis 35 is a central axis of the vessel 3 perpendicular to the bottom 5 of the vessel 3. When the vessel 3 is rotated by the rotating device 25, the side wall 7 of the vessel 3 passes through an illumination region 37 of the first inspection station 23, which is illuminated by the illumination device 27 of the first inspection station 23 and is shown in dashed lines in Figure 2A.

[0071] Fig. 3A shows a schematic sectional view in the area of ​​the first inspection station 23, wherein the sectional plane is a vertical plane parallel to a radial direction relative to the star wheel 13. In the illustrated embodiment, the illumination device 27 and the recording device 29 are each provided on opposite sides of the inspected vessel 3, so that the recording device 29 records images of the recording area 37 when the recording area 37 is illuminated in transmitted light. The recording device 29 preferably records the illumination area 37 through an optical system 60. The first recording unit 31 and the second recording unit 33 of the recording unit 29 can share the optical system 60. The optical system 60 can be designed as a telecentric optical system.

[0072] As can be seen from Fig. 3A, the rotating device 25 covers a partial area of ​​the vessel 3, so that the entire height of the vessel 3 cannot be illuminated by the lighting device 29 of the first inspection station 24. In the illustrated embodiment, the illumination area 37 illuminated by the lighting device 29 of the first inspection station 23 extends below the rotating device 25 of the first inspection station. In order to still be able to inspect the entire height of the side wall 7, the second inspection station 24 is provided. Fig. 2B is a view of the second inspection station 24 analogous to Fig. 2A. Fig. 3B is a view of the second inspection station 24 analogous to Fig. 3A. As can be seen from Fig. 2B and Fig. 3B, the rotating device 25 of the second inspection station 24 is arranged lower than the rotating device 25 of the first inspection station 23.The receiving area 37 of the second inspection station, illuminated by the lighting device 27 of the second inspection station 24 and imaged by the recording device 29 of the second inspection station 24, extends above the rotating device 25 of the second inspection station 24. If a vessel 3 is inspected successively in the first inspection station 23 and in the second inspection station 24, the side wall 7 can be inspected over the entire height of the side wall 7. The second inspection station 24 is designed analogously to the first inspection station 23, except for the changed height position of the rotating device 25, the lighting device 27, and the recording device 29 compared to the first inspection station 23. The function of the inspection stations 23, 24 will therefore be described below together for both inspection stations 23, 24.

[0073] Figure 4 shows a schematic representation of the illumination device 27 of one of the inspection stations 23, 24, viewed from the inspected vessel 3 toward the inspection station 23, 24. The illumination device 27 comprises a plurality of light sources 39, which, in the illustrated embodiment, are arranged in horizontal rows. The light sources 39 can be configured, for example, as LEDs. As shown in Figs. 1, 3A, and 3B, the illumination device 29 comprises a linear polarization filter 40 through which the illumination device 29 illuminates the illumination area 37.

[0074] As the side wall 7 of the vessel 3 passes through the illumination region 37 along the direction of rotation 36, the illumination pattern generated by the illumination device 27 in the illumination region 37 changes over time by alternately illuminating the illumination region 37 with two different illumination patterns. This can be done in the same way for both inspection stations 23, 24. As schematically shown in Figure 5, the illumination region 37 is illuminated periodically, alternately in a first time window 41 with a first illumination pattern 43 and in a second time window 45 with a second illumination pattern 47. First time windows 41, in which the illumination region 37 is illuminated with the first illumination pattern 43, and second time windows 45, in which the illumination region 37 is illuminated with the second illumination pattern 47, thus alternate periodically.

[0075] In the illustrated embodiment, the first illumination pattern 43 corresponds to an at least substantially homogeneous illumination of the illumination region 37. In the illustrated embodiment, the second illumination pattern 47 corresponds to an illumination of the illumination region 37 in which horizontal stripes of higher light intensity alternate with horizontal stripes of lower light intensity. The first recording unit 31 of the respective inspection station 23, 24 is configured to take a picture of the illumination region 37 in each first time window 41 and in each second time window 45. The picture images a region of the side wall 7 of the vessel 3 present in the illumination region 37 at the time of the respective picture being taken under the respectively present illumination (first illumination pattern 43 or second illumination pattern 47).

[0076] Figure 6 schematically shows the distribution of the images taken with the different illumination patterns 43, 47 in relation to the circumferential position of the side wall 7 of the vessel 3 facing the first recording unit 31 at the time of the recording. The radial lines in Figure 5 represent circumferential positions of the side wall 7 of the vessel 3 that were directly opposite each other in a corresponding recording of the first recording unit 31. Lines marked with the reference numeral 43 symbolize an image in which the illumination region 37 was illuminated with the first illumination pattern 43. Lines marked with the reference numeral 47 symbolize images in which the illumination region 37 was illuminated with the second illumination pattern 47 during the recording.

[0077] The device 1 comprises a computing unit 49, shown schematically in Figure 1. The computing unit 49 is configured to coordinate the recording device 29 and the illumination device 27 of the respective inspection station 23, 24, in particular to synchronize them by means of a trigger signal. The computing unit 49 is also configured to compile images from the recordings taken by the recording devices 29. In Fig. 1, a common computing unit 49 is provided for both inspection stations 23, 24. Alternatively, each inspection station 23, 24 could comprise its own computing unit, which can, for example, each communicate with a higher-level computing unit.

[0078] The images captured by the first recording unit 31 during the inspection of a vessel 3 in the first time periods 41, i.e., with the first illumination pattern 43, are combined to form a first image 51. The first image 51 is schematically shown in Fig. 7A. Opaque defects or imperfections in the side wall 7 may be visible in the first image 51.

[0079] The images captured by the first imaging unit 31 during the inspection of the vessel 3 in the second time window 45, i.e., with the second illumination pattern 47, are combined to form a second image 53. The second image 53 is schematically shown in Fig. 7B. Transparent defects or flaws in the side wall 7 may be visible in the second image 53.

[0080] In the described embodiment, the second recording unit 33 is configured to take a picture of the illumination area 37 in every first time window 41 during the inspection of a vessel 3. The second recording unit 33 comprises a polarization filter 54 (see Fig. 1), through which the second recording unit 33 records the illumination area 37. The polarization filter 54 can be a linear polarization filter. The polarization filter 54 can be rotated 90 degrees relative to the polarization filter 40 of the illumination device 27. Due to the crossed polarization filters, the resulting image can be virtually black. Stress-generating defects in the sidewall 7 that rotate the polarization plane of the light can be clearly visible in the image.

[0081] The images captured by the second recording unit 33 during the inspection of a vessel 3 during the first time window 41, i.e., with the first illumination pattern 43, are combined to form a third image 55. The third image 55 is schematically illustrated in Fig. 70. Since the images underlying the third image 55 were captured through the polarization filter 54, the third image 55 differs from the first image 51. Stress defects in the side wall 7 may be visible in the third image 55.

[0082] Preferably, a frequency of alternating between the first illumination pattern 43 and the second illumination pattern 47 is matched to the rotational speed of the vessel 3 and the width of the illumination region 37 such that the first image 51, the second image 53, and the third image 55 each depict an entire circumference of the side wall 7. The first image 51, the second image 53, and the third image 55 can be analyzed by the computing unit 49 or otherwise in order to detect defects or imperfections in the side wall 7. Since the first image 51, the second image 53, and the third image 55 are based on different illumination, different types of defects can be detected with varying degrees of clarity in the images.

[0083] For each inspection station 23, 24, a separate first image 51, second image 53, and third image 55 can be generated, representing the height range of the side wall 7 imaged by the respective inspection station 23, 24. Alternatively, the data from the two inspection stations 23, 24 can be combined, in particular by the computing unit 49, into a common first image 51, a common second image 53, and a common third image 55, which images the side wall 7 over the entire height of the side wall 7.

[0084] Figure 8 shows a schematic exploded view of the lighting device 27. The lighting device 27 comprises a substrate plate 57 on which the light sources 39 are arranged. A transparent cover plate 59 is provided above the substrate plate 57 to protect the light sources 39 from dust. A heat sink 61 is provided below the substrate plate 57 to dissipate heat generated by the light sources 39. The heat sink 61 is cooled by a fan 63.

Claims

Claims 1. Device (1) for inspecting vessels (3), comprising: a lighting device (27) configured to alternately illuminate a lighting area (37) with different lighting patterns, comprising at least a first lighting pattern (43) and a second lighting pattern (47), wherein the lighting device (27) is configured to illuminate the lighting area (37) with the first lighting pattern (43) in first time windows (41) and with the second lighting pattern (47) in second time windows (45); a rotating device (25) configured to rotate a vessel (3) having a bottom (5) and a side wall (7) about an axis (35) of the vessel (3) such that at least a section of the side wall (7) passes through the lighting area (37) along a direction of rotation (36);and a recording device (29) configured to take a recording of the illumination area (37) at least in every first time window (41) and in every second time window (45).

2. Device according to claim 1, wherein the first illumination pattern (43) corresponds to at least substantially uniform illumination of the illumination area (37) and the second illumination pattern (47) corresponds to illumination of different sub-areas of the illumination area (37) with different light intensities.

3. Device according to claim 1 or 2, wherein the lighting device (27) is configured to illuminate the lighting area (37) in a striped pattern when the lighting area (37) is illuminated with the second lighting pattern (47), in which stripes of lower light intensity alternate with stripes of higher light intensity.

4. Device according to one of the preceding claims, wherein the first illumination pattern (43) is configured to make a first type of defect in the side wall (7) detectable, and wherein the second illumination pattern (47) is configured to make a second type of defect in the side wall (7) detectable.

5. Device according to one of the preceding claims, further comprising a computing unit (49) which is configured to combine the recordings taken during the rotation of the vessel (3) in the first time windows (41) into a first image (51) and to combine the recordings taken during the rotation of the vessel (3) in the second time windows (45) into a second image (53).

6. Device according to one of the preceding claims, wherein the lighting device (27) comprises light sources (39) which participate both in illuminating the lighting area (37) with the first lighting pattern (43) in the first time windows (41) and in illuminating the lighting area (37) with the second lighting pattern (47) in the second time windows (45).

7. Device according to one of the preceding claims, wherein the lighting device (27) is configured to periodically change the brightness of at least one light source (39) of the lighting device (27), in particular by means of pulse width modulation.

8. Device according to one of the preceding claims, wherein the lighting device (27) comprises several groups of light sources (39), wherein the lighting device (27) is configured to control the light sources (39) of all groups of light sources (39) to emit the same luminous flux when illuminating the lighting area (37) with the first lighting pattern (43), and to control the light sources (39) of certain groups of light sources (39) to emit a different luminous flux than the light sources (39) of certain other groups of light sources (39) when illuminating the lighting area (37) with the second lighting pattern (47).

9. Device according to one of the preceding claims, wherein the lighting device (27) comprises an area array of light sources (39), wherein the distance between adjacent light sources (39) is not more than 10 millimeters, or not more than 7 millimeters, or not more than 5 millimeters, or not more than 4.5 millimeters.

10. Device according to one of the preceding claims, wherein the first time windows (41) and the second time windows (45) alternate at a frequency of at least 10 kilohertz, or at least 15 kilohertz, or at least 20 kilohertz, or at least 25 kilohertz, or at least 30 kilohertz, or at least 35 kilohertz, or at least 40 kilohertz, or at least 45 kilohertz, or at least 50 kilohertz.

11. Device according to one of the preceding claims, wherein the recording device (29) comprises a first recording unit (31) and a second recording unit (33), wherein the second recording unit (33) has a polarizing filter (54), wherein the first recording unit (31) is configured to take a recording of the illumination area (37) in each first time window (41), and wherein the second recording unit (33) is configured to take a recording of the illumination area (37) in each first time window (41).

12. Method for inspecting vessels (3), comprising: Rotating a vessel (3) with a bottom (5) and with a side wall (7) about an axis (35) of the vessel (3) such that at least one section of the side wall (7) passes through an illumination area (37) along a direction of rotation (36); Illuminating the illumination area (37) alternately with different illumination patterns, which include at least a first illumination pattern (43) and a second illumination pattern (47), wherein the illumination area (37) is illuminated with the first illumination pattern (43) in first time windows (41) and with the second illumination pattern (47) in second time windows (45); and Taking a recording of the lighting area (37) at least in every first time window (41) and in every second time window (45).

13. Method according to claim 12, wherein the recordings taken in the first time windows (41) are combined to form a first image (51), and the recordings taken in the second time windows (45) are combined to form a second image (53).

14. Method according to claim 12 or claim 13, wherein in each first time window (45) a further image of the illumination area (37) is taken, wherein the further image is preferably taken through a polarizing filter (54).

15. Method according to one of claims 12 to 14, wherein to change from the first illumination pattern (43) to the second illumination pattern (47) a plurality of light sources (39) is controlled by pulse width modulation, so that the luminous flux emitted by the light sources (39) is changed.

Images