METHOD AND DEVICE FOR INSPECTING CONTAINERS

Description

[0001] The present invention relates to a method and a device for inspecting containers. Such methods and devices have been known in the art for a long time. Typically, containers are transported individually by means of a transport device. During this transport, these containers are observed by cameras in order to detect certain properties, such as incorrectly applied labels, defects at the openings of the containers, or defects on the bottoms.

[0002] The invention relates to machines with video systems, particularly in the beverage manufacturing industry, which are used for the inspection, control, regulation, alignment, and / or sorting of containers or packages. The invention also relates to sensors for controlling machine and system functions. Examples include, as mentioned above, bottom, mouth, or sidewall inspections in an empty container inspection system. Furthermore, the invention can also be used for label closure or fill level checks, for example, after a filling or labeling machine, or in container sorting, such as before a cleaning machine.

[0003] Such machines typically include, in addition to the transport and image acquisition units, several trigger systems, such as light barrier systems, which serve to ensure that an image of the containers is captured at the correct moment. In a known embodiment, it is also known to trigger image acquisition directly by means of a trigger unit (and in conjunction with a light barrier). The disadvantage of this approach is that such a trigger or light barrier unit requires installation space, particularly upstream of the image acquisition unit. Furthermore, the trigger unit or its individual sensors must be connected to the transport unit and, in particular, wired. This trigger unit also typically includes mechanical components and one or more sensors, thus representing a cost factor in terms of acquisition and installation.In addition, the individual sensors require adjustment, occasional readjustment, and especially regular cleaning.

[0004] Due to wear and tear, for example from the elongation of a transport chain, the parameters of such a tracking system usually also need to be readjusted in order to maintain proper triggering.

[0005] In addition, the sensor devices can fail, for example due to a defect or lack of cleaning, thereby paralyzing the production of an entire plant.

[0006] Furthermore, the trigger unit often requires height adjustment, for example, to ensure triggering always occurs at the optimal vertical position for containers of varying heights. Alternatively, it would be conceivable to use multiple sensors at different heights or to install a vertical trigger light curtain. In a simpler scenario, where, for example, no rotary encoder is provided for driving the transport device, adjustment in the transport direction is also necessary, for instance, to align or pick up containers of different diameters in the correct position relative to their center plane in different production processes.

[0007] Furthermore, the trigger signal generation via the trigger unit, the trigger signal delay within the trigger unit, and the signal transmission all contribute to trigger uncertainty. This means that the image capture is not triggered precisely at the set target position for every container, but also shortly before or after. While some applications of these inspection machines are quite tolerant of a trigger uncertainty of 1 mm, others require very high trigger accuracy of well below 1 mm. These problems are further exacerbated by steadily increasing production speeds.

[0008] WO 2017 / 211974 A1 describes the inspection of containers on a conveyor belt using optical cameras. Foam generated by lubricant interferes with imaging; therefore, an ultrasonic device destroys the foam before inspection, improving reliability and eliminating the need for high-pressure air. WO 2018 / 007215 A1 concerns inspection units whose cameras see through protective glass. It features a special lighting and imaging system to detect contamination or damage to the protective glass itself and ensure accurate inspection without external visual distortions. US 2008 / 291438 A1 uses multiple cameras and lighting configurations to capture numerous images of each filled bottle. Potential defects are combined using stereovision and 3D modeling to determine whether particles are present in the liquid or on the container wall.

[0009] The present invention is therefore based on the objective of eliminating the need for such trigger systems in methods and devices for inspecting containers, or at least simplifying their design. It is also an objective of the invention to reduce or completely eliminate the aforementioned disadvantages, particularly with regard to operating costs, installation space, and trigger uncertainty. These objectives are achieved according to the invention by the subject matter of the independent claims. Advantageous embodiments and further developments are the subject matter of the dependent claims. In a method according to the invention for inspecting containers, the containers are transported along a predetermined transport path by means of a transport device. During transport, at least one image acquisition device acquires a spatially resolved inspection image of at least one area of ​​a container.of the containers. According to the invention, a triggering of this inspection image acquisition of the spatially resolved image is controlled, wherein this control takes into account a trigger image acquisition of an image of the container.

[0010] In contrast to the prior art, it is proposed that image capture is not controlled or triggered by a trigger system, including one or more trigger sensors such as a light barrier, but rather by the acquisition of another image, particularly of the same container. This allows for an initial trigger image of the container to be acquired, specifically to determine its position, and then the inspection image to be captured based on this information.

[0011] Preferably, the trigger image is acquired to capture the position of the container, and in particular its position in the transport direction. Preferably, the trigger image is acquired on the same container as the inspection image. Preferably, the trigger image is acquired before the inspection image.

[0012] Preferably, the time interval between the trigger image acquisition and the inspection image acquisition is less than 5 ms, preferably less than 2 ms, preferably less than 1 ms, and preferably less than 500 µs. Particularly preferred is a time interval between the trigger image acquisition and the inspection image acquisition greater than 0.1 µs, and preferably greater than 0.5 µs.

[0013] Preferably, the trigger image acquisitions are triggered repeatedly and / or cyclically, whereby an inspection image is preferably only triggered when the container to be inspected is depicted in a predetermined manner and, in particular, optimally for position determination in the trigger image. Preferably, otherwise no reaction occurs, and in particular, no image acquisition is triggered. One way to achieve this is to ensure that the cycle (or repetition rate) of the trigger image acquisitions is short enough so that each container is depicted optimally at least once. For example, if containers are to be transported on a single-lane conveyor at a speed of 2.0 m / s and the depiction of the containers in the trigger image acquisitions should not have an offset of more than 10 mm from image to image, then the cycle should not last longer than 5 ms.

[0014] Cyclical trigger image capture can preferably be either free-running, i.e., the camera always captures the next trigger image at the earliest possible time, whereby the specified maximum time for optimal imaging must never be exceeded, or it can be time- or distance-controlled in a fixed grid.

[0015] Preferably, the cycle or repetition rate of the recording of the trigger images is selected such that the image of the containers in the trigger image recordings has an offset of less than 30 mm, preferably less than 20 mm and particularly preferably less than 10 mm from image to image.

[0016] Preferably, at least two trigger images are taken. In particular, at least two trigger images are taken for each container to be photographed. Particularly preferably, a large number of trigger images are taken (especially for each container to be photographed), and in particular, a large number of trigger images are repeated cyclically.

[0017] Preferably, the trigger images are captured with a cycle or repetition rate of less than 40 ms, preferably less than 30 ms, preferably less than 20 ms and particularly preferably less than 10 ms.

[0018] Preferably, the trigger images are stored, at least temporarily. Preferably, the trigger images are captured and / or stored with at least one marker.

[0019] This marking information can preferably be information that is characteristic of the time the image was captured and / or the location of the container and / or the position of the transport device. Preferably, this marking information can be information that uniquely identifies the time the trigger image was captured and / or the location of the container and / or the position of the transport device.

[0020] Furthermore, it would also be possible to capture the trigger images with indexing information, such as a running number for each trigger image.

[0021] In a further preferred embodiment, the camera and / or light source are switched off for a predetermined area or period after an inspection has been taken, and in particular during a period in which, for mechanical reasons, no new container can be available for a renewed sequence of triggering and inspection image acquisition. Preferably, the idle time between the inspection image acquisition and the next triggering image acquisition is somewhat shorter than the time between the image acquisition positions of two containers positioned as close together as possible.

[0022] In another preferred method, the inspection image acquisition serves to inspect at least one area of ​​the container, in particular an inspection selected from a group of inspections including sidewall inspection, bottom inspection, mouth inspection, closure inspection, combinations thereof, and the like. In a further preferred embodiment, the containers are transported along a straight transport path. A corresponding device can, for example, have a single- or multi-lane conveyor, in particular a single-lane conveyor, on which the containers are arranged, in particular standing, in a predetermined orientation.

[0023] It is particularly preferred that the containers are moved essentially synchronously, especially synchronously with a transport chain or conveyor belt.

[0024] Furthermore, the position of a drive unit of the transport system is recorded, at least temporarily. Based on this position of the drive unit, the position of the transport system and / or the containers can be inferred, and this in turn can be used to trigger the image capture and, preferably, ultimately the inspection image capture.

[0025] A corresponding device, described in more detail below, can, for example, include a rotary encoder, which is arranged particularly on the transport device and which, for example, provides a corresponding number of path increments as a signal depending on the movement of a chain or conveyor belt. Preferably, a processor unit can also be provided which calculates a number of path increments.

[0026] Furthermore, a trigger unit preferably provides a trigger signal, particularly when a container passes by. A trigger unit can be provided for this purpose. According to the invention, this trigger unit particularly includes an image acquisition device, preferably, as explained below, the same image acquisition device that also serves to capture the inspection image. In particular, this trigger unit provides a trigger signal when the containers pass by.

[0027] In addition, a detection device may be provided which is capable of recognizing both upright and lying containers.

[0028] The containers in question are generally bottles or beverage bottles made of glass or plastic, beverage cans or secondary packaging such as beverage crates or cardboard outer packaging.

[0029] Additionally, detection devices for beverage cans may be provided. These could, for example, be inductive proximity sensors.

[0030] In a preferred embodiment, a tracking unit is also provided, which delays generated trigger signals, for example, by a predetermined number of path increments. In this case, for example, image acquisition can be controlled and / or triggered depending on the trigger image captured by the image acquisition device. Such a unit can be located in the image acquisition device itself or in an external tracking controller. Particularly when containers of different diameters and / or in different production locations are to be triggered in a positionally accurate manner relative to their central axis, the adaptation to a container diameter can be achieved by using a different number of path increments.

[0031] Preferably, the images are captured using a camera, which particularly preferably comprises one or more industrial cameras, each of which is particularly preferably equipped with an imaging lens for image capture. This capture can be triggered by a trigger signal, which particularly preferably originates from the same image capture device.

[0032] Furthermore, as described in more detail below, the containers are illuminated for inspection purposes. A suitable device may include a lighting unit. This lighting unit can provide continuous light or be switchable, as described in more detail below. Alternatively, continuous light may be provided, which is switched off, for example, after a prolonged period of inactivity of a camera.

[0033] Furthermore, it is also conceivable that triggering can be highly precise or container-specific, and even synchronous with image acquisition. This can involve the use of an illumination trigger, which is either controlled by the image acquisition itself, or the image acquisition device and the illumination can both process trigger signals with minimal delay, particularly within a few microseconds, and are preferably controlled by the trigger signal.

[0034] Furthermore, depending on the task, the lighting can be arranged in different ways and emit different types of light. As mentioned in more detail below, this can include incident light lighting, transmitted light lighting, or even dark field lighting.

[0035] In addition, it would also be conceivable to combine several types of lighting or exposure times.

[0036] In another preferred embodiment, an image processing system is provided which receives the images from an image acquisition device, for example, via a corresponding camera interface. In addition, these images can be processed, and processing information can be generated, such as sorting information or pass / fail signals. Such a processing system can also be integrated into the image acquisition device itself or be installed externally.

[0037] In another preferred method, the trigger image is captured by the image acquisition device, specifically by the same image acquisition device that also captures the inspection image. This method thus proposes self-triggering of the camera by a previously captured image.

[0038] Preferably, the trigger image is taken from the same container from which the inspection image is taken.

[0039] In another preferred method, the containers are transported individually. In particular, the containers are transported at a predetermined distance from each other, and especially at a distance from each other that is smaller than the cross-sectional area of ​​a container.

[0040] Preferably, the image acquisition device captures both the trigger image and the inspection image.

[0041] In another preferred method, the trigger image acquisition and the inspection image acquisition differ in at least one parameter characteristic of the image acquisition. This means that, in particular, technical parameters for the image acquisition are changed, and preferably, an essentially identical image is not acquired twice.

[0042] Among the parameters characteristic of image acquisition, a parameter is understood to be, in particular, a parameter that is characteristic of or influences properties of the image acquisition device, and especially a repetition rate. In a preferred method, the parameter is selected from a group of parameters that includes a resolution of the captured image, a size of the captured image, a data size of the captured image, an area of ​​the captured region of the container, a color depth of the captured image, a frame rate, an illumination parameter such as illuminance, color, or direction, and the like.

[0043] A parameter that allows for a higher frame rate is particularly preferred for the trigger image. For example, it is possible to capture the trigger image at a lower resolution. However, it would also be possible, and / or additionally, to capture a smaller area of ​​the container for the trigger image.

[0044] As mentioned, the different parameters allow for different repetition rates. This makes it possible to capture the next inspection image immediately after the trigger image. This subsequent image can then be captured with an increased or even maximum resolution.

[0045] It would also be conceivable that the further inspection image is recorded during a period of time corresponding to a certain geometric dimension of the containers, for example half the container diameter.

[0046] In another preferred method, the inspection image acquisition is controlled taking into account the transport speed of the containers. First, the trigger image is acquired, and then the actual image acquisition is controlled or triggered based on this trigger image, using the transport speed and / or the instantaneous position of the container.

[0047] In another preferred method, the container is illuminated at least temporarily during the acquisition of at least the inspection image and / or during the trigger image acquisition. This improves the image acquisition itself or even makes it possible to acquire an image under defined conditions. This can be particularly advantageous with constantly increasing transport speeds. In these cases, the image acquisition device must cope with ever shorter image opening times. These increasingly shorter times can be at least partially compensated for by correspondingly stronger illumination.

[0048] In another preferred method, the container is pulsedly illuminated during the acquisition of the inspection image. A flash lamp control can be used, which illuminates the container with a flash of light during image acquisition.

[0049] Preferably, this illumination or illumination pulse is also controlled taking the trigger image into account. In particular, the trigger image can directly activate the illumination device; however, indirect activation, especially via the image acquisition device, would also be possible. Conversely, it would also be possible for the acquisition of the inspection image to be triggered, for example, by a light pulse. Even in this case, however, the inspection image acquisition is triggered indirectly, primarily by the acquisition of the trigger image.

[0050] It would also be conceivable to illuminate the container for the trigger recording with continuous light.

[0051] In another preferred method, the position of the container is recorded temporally and / or spatially for the purpose of triggering the inspection. In this case, it is possible to record the position, and in particular at least a rough position, of the container on the transport device even before the inspection is triggered. For this purpose, for example, light barriers can be used. Thus, it is possible for a light barrier to first detect the approximate location of the container, then for the image acquisition device to take a trigger image, and finally for the actual inspection image to be taken by the image acquisition device based on this trigger image.It is therefore advantageous for such a light barrier arrangement to be positioned in the transport direction of the containers in front of the image acquisition device and is particularly preferred as a basis for the trigger shots of several independent camera systems which can be arranged in a geographically distributed manner.

[0052] In a further preferred method, the recording of the inspection image is triggered by taking into account a trigger condition, wherein this trigger condition is preferably selected from a group of trigger conditions which includes a change in the mean brightness in a trigger image section, a change in the contrast of the individual pixels in an image section, a change in the variance and / or spatial frequency of the image brightnesses of individual pixels, the detection of a specific pattern and / or the detection of a specific color.

[0053] For example, the image capture device could be set to detect a specific element of a label, and the exact position of the container on the transport system could be determined based on the position or the detected position of this feature. Based on this data, the increments or the time after which the actual image is triggered could be calculated.

[0054] The present invention further relates to a device for inspecting containers, which has a transport device that transports the containers along a predetermined transport path.

[0055] Furthermore, the device comprises a first image acquisition device which is suitable and intended to capture at least one spatially resolved inspection image of at least one area of ​​a container during the transport of the containers, wherein the device comprises a triggering device which is suitable and intended to control the resolution of the inspection image acquisition of the spatially resolved image.

[0056] According to the invention, this triggering device comprises at least one image acquisition device and, in particular, the first image acquisition device, which is suitable and intended to capture a triggering image of the container during the transport of the container.

[0057] The image recording device is therefore preferably suitable and designed to capture an image of the container even during its movement.

[0058] In a preferred embodiment, the transport device has a conveyor belt on which the containers are conveyed upright. However, it would also be conceivable for the transport device to have one or two lateral guide belts between which containers can be conveyed.

[0059] In a further advantageous embodiment, the transport device has a motorized, and in particular an electric motor, drive. Advantageously, the transport device also has a control device for controlling the transport device and, in particular, for controlling the drive device of the conveyor belt. Advantageously, the drive device has a stepper motor or a motor whose rotational position can be detected. Advantageously, the transport device has a detection device that can detect at least one position of a component of the transport device, such as the position of a conveyor belt.

[0060] In a further advantageous embodiment, the triggering device also takes into account a transport speed and / or a position of the containers on the conveyor belt.

[0061] In a further advantageous embodiment, the image acquisition device is switchable between at least two image acquisition modes, wherein the inspection image is captured in a first image acquisition mode and the trigger image in a second image acquisition mode. As mentioned above, these trigger modes preferably differ in at least one property, such as image resolution or the like.

[0062] In a further advantageous embodiment, the device has an additional detection device which is suitable and intended for detecting the position of the container along the transport path. Advantageously, this additional detection device is arranged in the container's movement mechanism upstream of the image acquisition device. This additional detection device can, in particular, serve to at least roughly predetermine the geometric position of the containers before they reach the image acquisition device or its detection area. Preferably, however, this additional detection device does not serve to directly trigger the inspection image acquisition.

[0063] Preferably, this detection device includes at least one detection sensor, such as a light barrier.

[0064] In a further advantageous embodiment, the device comprises at least one lighting device suitable and intended for illuminating the containers, at least during image acquisition. This lighting device can comprise a plurality of light sources, for example, a plurality of LEDs. Furthermore, it is possible for this lighting device to be arranged with respect to the transport path of the containers such that the containers are illuminated or conveyed between the image acquisition device and the lighting device.

[0065] However, it would also be possible for the lighting device to be arranged so that the containers are illuminated using reflected light. In this case, the lighting device could be positioned on the same side as the image acquisition device with respect to the transport path of the containers.

[0066] In general, it is possible for the image processing device itself to generate a (particularly highly accurate) trigger signal, thus eliminating the need for the external trigger unit typically used in the prior art. As mentioned above, this can be achieved, for example, by having the image acquisition device (or a master camera in a synchronous multi-camera application) capture partial images at a high frequency, e.g., > 500 Hz, within a small area of ​​the image sensor chip, and then checking whether a trigger condition has been met.

[0067] It is also possible to transmit the trigger signal, generated with high precision by the image processing unit, to one or more downstream image acquisition units with a temporal and / or spatial delay. This advantageously eliminates the need for additional trigger illumination that might be required at the master system.

[0068] Preferably, by selecting a horizontal and vertical position of the image section on the sensor surface, the triggering can also be easily adapted to different objects to be triggered (for example, using a computer program).

[0069] Preferably, the image section is at most half the size of the entire chip area of ​​the image sensor, preferably it is at most 25% of this chip area, preferably at most 10% of this chip area.

[0070] This reading and evaluation of the trigger condition can be performed hardware-based within the camera itself or in a dedicated image processing system. In this case, evaluation is possible within a few microseconds, and therefore faster and with a higher degree of temporal determinism compared to an external trigger solution.

[0071] Preferably, the camera's image capture is triggered as soon as the trigger condition is met, although this can preferably also be done by means of a specific time offset.

[0072] If one or more slave cameras and / or flash illuminators are assigned to the image acquisition device, this trigger signal can also be passed on to these units via a correspondingly fast interface, since the image acquisition devices and flash illuminators should be triggered practically simultaneously, i.e. typically with a maximum offset in the single-digit µs range.

[0073] In general, a drop or rise in the average brightness in a trigger image section above or below a defined absolute threshold or by more than a defined jump height can occur or be present.

[0074] A decrease or increase in the contrast of individual pixels in an image section can also be used, for example, to trigger on a light-dark edge. This can be done selectively on a horizontal edge, such as the edge of a label, or a vertical edge, such as on a bottle lying on its side.

[0075] In addition, as mentioned above, a decrease or increase in the variance and / or spatial frequency of the image brightness can also be used, for example to trigger on a 1D or 2D code that typically has very high and rapidly changing spatial contrasts.

[0076] In addition, a specific pattern can also be identified within the given conditions by means of a simple pattern comparison.

[0077] In addition, a specific color or color within a color subspace can also be identified.

[0078] These methods are not limited to a single image section; multiple sections or multiple such methods could be evaluated, and the individual results linked, particularly logically linked, to generate the trigger conditions. This could be advantageous, for example, when sorting containers of different sizes that pass through the image processing unit in a mixed order.

[0079] In order to enable, on the one hand, free-running image capture within the image area at a high frequency for triggering, and on the other hand, to also enable triggered capture of an entire image, it is possible, as mentioned above, to provide both a trigger light and a main light.

[0080] For example, lighting can be provided in continuous light or switched continuous light mode, which is active when containers are being filled.

[0081] This lighting is preferably used both as trigger lighting and as main lighting.

[0082] In addition, a flashable lighting system could be provided, for example, a transmitted light surface lighting system that illuminates a defined area or even the entire illuminated surface continuously as a trigger light. This continuous light can shine at a significantly reduced brightness, especially if this is sufficient for triggering.

[0083] In addition to a flashable main light source, a trigger light can also be installed within a continuous light source, which is particularly useful for machine vision systems using incident light. The trigger light and the vision light can differ in their illumination type, for example, one using incident light and the other transmitted light. These light sources can also differ in wavelength, color, or other characteristics.

[0084] The inventive method achieves significantly more flexible trigger conditions compared to an external trigger solution, such as one based on photoelectric sensors. Photoelectric sensors can typically only react to changes in contrast. Furthermore, it reduces the complexity of the mechanics, encoders, trigger sensors, wiring, and adjustments, thus resulting in cost savings. It also enables more precise and faster triggering in a simple manner.

[0085] Furthermore, no mechanical adjustment of the trigger unit or multiple sensors is required when changing formats.

[0086] By selecting a trigger image section in the transport direction of the container, the object's position in the camera image can be easily varied. Furthermore, increased operational reliability is achieved, thereby also increasing system efficiency, since, for example, a failure of the trigger sensors, insufficient maintenance of the sensors or the tracking system no longer affects system availability.

[0087] In addition, a trigger signal originating from a machine vision system according to the invention can be delayed, for example by means of a tracking system and path increments, and made available to a downstream inspection system.

[0088] In a further advantageous embodiment, the device has an ejection device which is suitable and intended to eject certain containers from a transport path or product path.

[0089] Further advantages and embodiments can be seen from the attached figures.

[0090] It shows: Fig. 1 A schematic representation of a device according to the invention; Fig. 2 A representation of a sequence of a method according to the invention; Fig. 3 A representation to explain image acquisition; Fig. 4 A representation of the sequence of the method according to the invention.

[0091] Figure 1 Figure 1 shows a schematic representation of a device 1 according to the invention for inspecting containers. Containers 10 are transported along a predetermined transport path T by means of a transport device 2. Here, the transport device 2 has a conveyor belt on which the containers are conveyed.

[0092] Reference numeral 4 designates an image acquisition device that observes the containers transported in the transport direction T. This image acquisition device 4 captures a spatially resolved image of each individual container.

[0093] Reference numeral 8 indicates a lighting device which is arranged here on the opposite side from the image recording device 4 with respect to the individual containers 10.

[0094] The reference symbol R1 roughly schematically indicates the trigger condition. If this condition is met, image acquisition is triggered by the image acquisition device 4.

[0095] Reference numeral 12 designates a further light barrier which detects the entry of containers 10 into the device 1 according to the invention. Reference numeral 22 designates a control device and, in particular, a rotary encoder by means of which a position of the transport device or also a rotational position of the drive of deflection rollers of the transport device can be detected. This data is also taken into account to trigger image acquisition by the image acquisition device 4.

[0096] Figure 2Figure 3 shows a schematic sequence of a method according to the invention. First, in step 30, a live camera is started. In process step 31, the container is moved to the center of the image. Furthermore, in step 32, a trigger and optionally a recording area are defined. However, the entire image can also be evaluated for the actual recording. In step 33, a trigger condition is defined or trained. In step 34, a trigger condition can be activated. In step 35, it is checked, for example by means of a high-speed recording in a small trigger area, whether the trigger condition is met. If the trigger condition is met (step 36), a recording of the entire image or a section of the image is triggered. If the trigger condition is not met, a recording is triggered again in step 35.This means that this loop will be executed until the trigger condition is met.

[0097] After the image is captured in step 37, the image is transmitted (e.g. to a sorting unit) in step 38.

[0098] Figure 3 This diagram illustrates how to create an image capture. Reference symbol 40 refers to a complete image that may be captured. Reference symbol 41 refers to capturing a section of an image, specifically a section containing a particular image. The trigger condition can be defined within and / or outside this image, for example, an area of ​​the image that is particularly suitable for trigger evaluation.

[0099] In this way, the trigger image is significantly smaller than the image to be captured later, which in particular enables a high frame rate. It is conceivable that the image acquisition device captures images or trigger images at a frame rate of up to several kHz. The image acquisition device can repeat the trigger captures until the object is "captured" or located in the correct position.

[0100] Once the trigger condition is met, the inspection image is captured. This image capture is not limited to a single image, but can also include multiple images, preferably with switching of the illumination direction or type.

[0101] Figure 4Figure 1 shows a further embodiment of a method according to the invention. Here, a trigger light barrier 66 is used to first roughly detect whether a container is present in a specific area located in front of the actual image acquisition device 4. The container frequency can be, for example, 72,000 containers per hour, meaning a repetition frequency from one container to the next can be 20 Hz.

[0102] This results in a time interval of approximately 50 ms between two containers. Once the position of a specific container has been detected, the path to the approximate position 52 of the image acquisition device can be determined using high-frequency pulses 56. The high-frequency pulses are determined by the rotary encoder connected to the conveyor belt. The path from the trigger light barrier 66 to the approximate image acquisition device 4 is then calculated. Fig. 4 Illustrated with an example of 39 high-frequency pulses.

[0103] From point 52 onwards, the following applies: Figure 3 described procedure, i.e., by means of (high-frequency 53) trigger image recordings, the exact position of the container in front of the image recording device 62 is determined in order to carry out one or more inspection image recordings when this position is reached.

[0104] Reference numeral 54 indicates the area in which a lighting device and / or the image acquisition device is activated, for example to deactivate the lighting device during the period not required, i.e. before and after 54, and thus to reduce the power consumption or heat generation of the light source(s).

[0105] The image acquisition device has an exposure time that is preferably greater than 1 µs, preferably greater than 3 µs, preferably greater than 5 µs, and particularly preferably greater than 10 µs. Particularly preferably, an exposure time is selected that is less than 1 s, preferably less than 800 µs, preferably less than 500 µs, preferably less than 300 µs, preferably less than 200 µs, and particularly preferably less than 100 µs.

[0106] The applicant reserves the right to claim all features disclosed in the application documents as essential to the invention, provided they are novel individually or in combination compared to the prior art. It is further noted that the individual figures also describe features which may be advantageous on their own. A person skilled in the art will immediately recognize that a particular feature described in a figure may be advantageous even without incorporating other features from that figure. Furthermore, a person skilled in the art will recognize that advantages may also arise from a combination of several features shown in individual or different figures. Reference symbol list

[0107] 1 Device 2 Transport device 4 Image acquisition device 8 Lighting device 10 Containers 12 Light barrier 22 Control device 30-35 Process steps 37-39 Process steps 36 Trigger condition 40 Overall image 41 Image section capture 52 Approximate position 53 High-frequency trigger image captures 54 Area in which lighting device is activated 55 Area 56 High-frequency pulses 62 Image acquisition device 64 End of expectation area 66 Coarse detection Container; Trigger light barrier R1 Trigger condition T Transport path

Claims

1. Method for inspecting containers (10), wherein the containers (10) are conveyed along a predetermined transport path by a transport device (2) and wherein an image recording device (4) records at least one spatially resolved inspection image of at least one area of the containers during the transport of the containers (10), characterized in that a triggering of the inspection image recording of this spatially resolved image is controlled, wherein this controlling takes place in consideration of a triggering image recording of an image of the container, wherein the triggering image recording is carried out by the image recording device, and further wherein the triggering image recording and the inspection image recording differ in at least one parameter characteristic for the image recording.

2. Method according to the preceding claim, characterized in that the parameter is selected from a group of parameters containing a resolution of the recorded image, a size of the recorded area of the container, a color depth of the recorded image, a refresh rate, an illumination parameter such as intensity of illumination, illumination color or direction of illumination and the like.

3. Method according to at least one of the preceding claims, characterized in that the inspection image recording is controlled in consideration of a transport speed and / or a path of the containers.

4. Method according to at least one of the preceding claims, characterized in that the container is illuminated at least at times during the recording of the inspection image and / or during the triggering image recording.

5. Method according to the preceding claim, characterized in that the container is illuminated in a pulsed manner during the recording of the inspection image.

6. Method according to at least one of the preceding claims, characterized in that a position of the container is detected at a time and / or at a location prior to the performance of the triggering recording.

7. Method according to at least one of the preceding claims, characterized in that the triggering of the inspection image recording takes place in consideration of a triggering condition, wherein preferably this triggering condition is selected from a group of triggering conditions which contains a change of the average brightness in a trigger image section, a change of a contrast of individual pixels in an image section, a change in the variance and / or spatial frequency of the image brightnesses of individual pixels, the detection of a specific pattern and / or the detection of a specific color.

8. Method according to at least one of the preceding claims, characterized in that a plurality of triggering image recordings is performed and in particular a plurality of triggering image recordings is repeated in particular cyclically.

9. Apparatus (1) for inspection of containers (10), having a transport device which transports the containers (10) along a predefined transport path, having a first image recording device (4) which is suitable and intended to record at least one spatially resolved inspection image of at least one area of the container (10) during the transport of the containers (10), wherein the apparatus (1) comprises a triggering device (4) which is suitable and intended to control the triggering of the inspection image recording of the spatially resolved image, characterized in that the triggering device has at least one image recording device (4) and in particular the first image recording device which is suitable and intended to record a triggering image of the container (10) during the transport of the container (10), wherein the triggering image recording is carried out by the image recording device, and further wherein the triggering image recording and the inspection image recording differ in at least one parameter characteristic for the image recording.

10. Apparatus (1) according to claim 9, characterized in that the image recording device is switchable between at least two image recording modes, wherein in a first image recording mode the inspection image is able to be recorded and in a second image recording mode the triggering image is able to be recorded.

11. Apparatus (1) according to at least one of the preceding claims, characterized in that the apparatus (1) has a further detection device (12) which is suitable and intended to detect a position of the container (10) along the transport path.

12. Apparatus (1) according to at least one of the preceding claims, characterized in that the apparatus (1) has at least one illumination device (8) which is suitable and intended to illuminate the containers at least during an image recording.