Method and device for inspecting cylindrical containers
Patent Information
- Application Number
- EP2023717468
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2022-05-19
- Filing Date
- 2023-04-04
- Publication Date
- 2025-03-26
AI Technical Summary
Existing methods for inspecting cylindrical containers using line scan cameras are limited as they can only inspect one container at a time, require complex movement mechanics that introduce inaccuracies and disruptions, and suffer from optical distortions due to the rounded shape of the containers.
The use of an area camera with a two-dimensional recording medium that captures sequences of pixel lines aligned to a predetermined area of the container, allowing multiple containers to be inspected simultaneously without moving the camera, and employing optical lens systems to minimize distortions.
Enables efficient inspection of multiple cylindrical containers with reduced mechanical errors and improved accuracy by creating two-dimensional line images that clearly display contaminants, eliminating the need for complex camera movement and minimizing distortions.
Smart Images
Figure 1.1
Abstract
Description
[0001] Title: Method and device for inspecting cylindrical containers
[0002] Description
[0003] The invention relates to a method for inspecting cylindrical containers having the features of claim 1 and to a device for inspecting cylindrical containers having the features of claim 10.
[0004] When inspecting cylindrical containers, a line scan method can be used. This involves using a line scan camera. The line scan camera can record lines of pixels aligned with an object. A pixel line can be represented by individual pixels arranged next to one another along a straight line. A pixel line can be described as a (pixel) vector. The pixel line can be viewed as one-dimensional. One dimension of an object can be recorded or represented using the pixel line. The containers to be inspected are moved in a transport direction and rotated in the process. The containers are guided past the line scan camera so that the line scan camera can capture one of the containers.
[0005] From a starting position, the line-scan camera is moved in the transport direction along with the container being scanned. The line-scan camera successively captures a multitude of pixel lines of the container. The line images are then combined to form a (two-dimensional) line image. For a cylindrical container, such a line image corresponds, for example, to the unwrapped outer surface of the cylindrical container.
[0006] Possible damage to the containers and / or foreign objects within the containers can be better displayed or detected in such a line image. One reason for this is that optical distortions (e.g., due to the rounded shape of the containers being inspected) are minimal in a (one-dimensional) pixel line compared to a conventional (two-dimensional) area image.
[0007] Once the line scan camera has captured enough images (or pixel lines), it is moved back to its starting position, where it can capture the next container. The line scan camera must then be moved along with the next container in the transport direction and then returned to its starting position. This process is repeated for each container to be inspected.
[0008] The line scan camera must therefore be moved back and forth along the transport direction. Various motion mechanisms can be used for this purpose.
[0009] Alternatively, movable mirror optics can be used to track the movement of the transported container. Various motion mechanisms can also be used here.
[0010] The disadvantage is that the line scan camera can only inspect one container at a time. Furthermore, it requires a motion mechanism, which can be a source of disruptions, errors, inaccuracies, etc.
[0011] It is therefore an object of the present invention to provide a method and a device for inspecting cylindrical containers, wherein the above disadvantages are eliminated.
[0012] The above object is achieved by a method for inspecting cylindrical containers having the features of claim 1. The containers can be rotationally symmetrical containers, such as bottles, vials, ampoules, or syringes. The containers can be transparent (see-through), in particular to the human eye.
[0013] The method comprises the steps of: providing an area scan camera with a detection area. The area scan camera is in particular a camera with a two-dimensionally arranged recording medium. The area scan camera can have a sensor (e.g. CCD sensor) which has a matrix of pixels (image pixels), which enables two-dimensional (area) image recording with only one exposure cycle. The detection area is in particular two-dimensional. The detection area can be designed as a (in particular rectangular) detection plane.
[0014] Preparing the containers (to be inspected).
[0015] Transporting the containers in a transport direction through the detection area of the area-scan camera. The transport direction can be a straight line and / or at least partially a circular or elliptical path. The containers can be transported continuously or step by step.
[0016] Rotating the containers and / or a liquid held in the containers around a longitudinal axis of the respective container in a direction of rotation while the containers are located in the detection range of the area scan camera.
[0017] Recording (reading out) at least one sequence of pixel lines using the area scan camera. The pixel lines are aligned to a specified area of a container. In particular, the liquid in the container is rotated, while the container itself is not rotated. The containers can be set in rotation before the detection area. Before the containers are moved into the detection area, their rotational movement can be stopped so that they are no longer rotated. However, the liquid inside the containers continues to rotate. This means that the containers can be transported through the detection area; the containers are not rotated in the detection area, but the liquid inside the containers is rotated.
[0018] Alternatively, the pixel rows are aligned to a specified area of a container from various rotational positions of the container. In particular, the containers (including the liquid) are rotated as they are moved through the detection area.
[0019] In particular, each of the recorded pixel rows corresponds to a one-dimensional image.
[0020] A pixel row can be formed by individual pixels arranged side by side along a straight line (pixel row). It is also conceivable that a pixel row can be formed by two or more adjacent pixels arranged side by side along a straight line (two or more adjacent pixel rows).
[0021] While the container is moved through the detection area of the area scan camera, a sequence of pixel rows can be created (recorded) for each container. The pixel rows can be recorded one after the other. For example, a first pixel row can be recorded at a first point in time and a second pixel row adjacent to the first pixel row can be recorded at a second point in time after the first point in time. In other words, a first pixel row can be recorded at a first point in time. A second pixel row can be recorded at a second point in time. A third pixel row can be recorded at a third point in time, and so on. The first, second and third pixel rows can each represent (temporally) successive pixel rows. In other words, the pixel rows can be recorded one after the other.The first, second and third pixel rows can each be (spatially) adjacent pixel rows or can be represented by (spatially) adjacent pixels.
[0022] The pixel lines are recorded one after the other in time and space.
[0023] This allows the container to be tracked as it is transported through the detection zone of the area-scan camera. The area-scan camera does not need to move with the container.
[0024] According to a further development, at least two sequences of pixel lines can be recorded (read out) at least partially simultaneously using the area-scan camera. The pixel lines of each sequence can be aligned to a predefined area of a different container. The pixel lines of each sequence can be aligned to a predefined area of a different container from different rotational positions of the respective container.
[0025] This allows multiple containers to be tracked as they are transported through the detection area. This means that multiple containers can be inspected simultaneously with the same area scan camera.
[0026] According to a further development, the predetermined region of a container to which the pixel lines of a sequence are aligned can be a longitudinal axis of the container. In other words, the pixel lines of a sequence can be aligned with the longitudinal axis of a container. In other words, a pixel line can always run along the longitudinal axis, in particular the longitudinal center axis, of a container. If several sequences of pixel lines are recorded, the pixel lines of the individual sequences of pixel lines can be aligned with the longitudinal axes of the respective containers.
[0027] According to a further development, at least one line image can be created from a recorded sequence of pixel lines. In other words, several pixel lines, in particular those that are consecutive in time and preferably in space, can be combined to form a line image. Each line image can be considered to be composed of a plurality of pixel lines arranged next to one another, in particular those that are consecutive in time and preferably in space.
[0028] The line image can be analyzed to determine the inspection result. The line image can reveal, for example, whether there are contaminants in the container or in the liquid contained in the container.
[0029] The line image is designed, in particular, as a two-dimensional image. From such a line image, for example, impurities in the container can be particularly well detected. According to a further development, the method can comprise the following step:
[0030] Aligning the area scan camera, the detection zone, and / or the transported containers such that the containers remain in the detection zone of the area scan camera for as long as possible during transport through the detection zone. This can be achieved, for example, by orienting the detection zone as parallel as possible to the transport direction. The transport direction can be parallel to the detection zone. In particular, the transport direction can run within the detection zone designed as the detection plane.
[0031] This allows for maximum utilization of the detection area. For example, depending on the exposure time of the area-scan camera and the rotation speed of the containers (or the liquid contained in the containers), as many pixel lines as possible and the resulting composite line images of each container can be created. This can lead to improved inspection results.
[0032] In addition, the mechanical backward movement of a swivel arm or a mirror optic, which would otherwise have a time-consuming effect, is eliminated. This means that the inspection time increases accordingly due to the eliminated backward movement.
[0033] According to a further development, the method may comprise the step of providing an optical lens system (and / or at least one objective lens), in particular at least one telecentric, one bi-telecentric, and / or one endocentric objective lens, to avoid image distortions when recording the sequence of pixel lines using the area scan camera. In this way, distortions can be avoided or at least reduced, leading to a more precise inspection result.
[0034] According to a further development, the procedure may include the step :
[0035] Generating a trigger signal dependent on the movement of the containers, wherein the trigger signal is used to synchronize a sequence of pixel lines with at least one moving container. Thus, the movement of the containers can be synchronized with the generation of pixel lines, thus compensating for the movement of the container. The trigger signal can be dependent on the position of the containers.
[0036] The timing of the inspection can be controlled by at least one parameter to compensate for the movement of the containers. Such a parameter can be, for example, a start / stop or pixel line acquisition signal, a shift by a specific number of pixel lines (or pixel rows), a container number selection or input, a first pixel line (or pixel row) for acquisition, and / or a synchronous / asynchronous mode.
[0037] According to a further development, the recording of at least one pixel line can be carried out by displaying the pixels (pixel row or pixel rows) of the area camera contributing to the pixel line and
[0038] Hiding pixels that do not contribute to the pixel line
[0039] (pixel row or pixel rows) of the area camera. The display or hiding of the respective pixels
[0040] (pixel row or rows) can be implemented, for example, by activating or deactivating the individual sensors on an image sensor or its pixel matrix. An image sensor can be in the form of a chip, e.g., a CCD chip, a CMOS chip, etc.
[0041] According to a further development, the fading in and / or out of the pixels of the area camera for generating at least one pixel line can be synchronized with the movement of a container, in particular with its position, using the trigger signal. This makes it easy to create a sequence of pixel lines synchronized with the movement of the container.
[0042] The above object is further achieved by a device for inspecting cylindrical containers having the features of claim 10. The containers can be rotationally symmetrical containers, such as bottles, vials, ampoules, or syringes. The containers can be transparent (see-through), particularly to the human eye.
[0043] The device comprises a transport device for transporting the containers in a transport direction. The transport device can be designed to transport (move) the containers continuously or step by step. The device further comprises at least one rotation device for rotating the containers and / or a liquid held in the containers about a longitudinal axis of the respective container in a rotational direction.
[0044] The device also comprises an area-scan camera with a detection zone. The area-scan camera and / or the transport device are designed and arranged such that the containers pass through the detection zone of the area-scan camera.
[0045] The device is configured to record at least one sequence of pixel lines using the area-scan camera. The pixel lines are aligned to a predetermined area of a container or to a predetermined area of a container from various rotational positions of the container. The device is further aligned to combine the recorded sequence of pixel lines into a line image.
[0046] The pixel lines are recorded sequentially in time and space.
[0047] This allows the containers to be tracked as they are transported through the detection zone. The area scan camera does not need to move with the containers.
[0048] According to a further development, the area-scan camera can be arranged immovably in the device. In other words, the area-scan camera can be fixed and thus cannot be moved. In particular, the area-scan camera does not move with the containers in the transport direction. In this way, movement mechanisms for the area-scan camera can be dispensed with.
[0049] According to a further development, the device can comprise a lens system. The area-scan camera can have a lens. The device or the area-scan camera can comprise at least one lens. The lens can be a telecentric, a bi-telecentric, or an endocentric lens. In this way, image distortions when recording a sequence of pixel lines using the area-scan camera can be avoided or at least reduced.
[0050] According to a further development, the device can be configured to carry out a method according to the above. Regarding the advantages thereby achievable, reference is made to the relevant explanations of the method. The measures described in connection with the method and / or those explained below can serve to further refine the device.
[0051] Further features, details, and advantages of the invention will become apparent from the wording of the claims and from the following description of exemplary embodiments with reference to the drawings. They show, schematically:
[0052] Fig. 1 shows a device for inspecting containers;
[0053] Fig. 2 shows a pixel line recorded by an area camera; Fig. 3 shows an illustration of a method for inspecting containers using the device of Figure 1 and
[0054] Fig. 4 is an illustration of a further embodiment of the method for inspecting containers using the device of Fig. 1.
[0055] In the following description and in the figures, corresponding components and elements bear the same reference symbols. For the sake of clarity, not all reference symbols are shown in all figures.
[0056] Figure 1 schematically shows a device 32 for inspecting containers 10. The containers 10 are, in this case, vials filled with a liquid 18.
[0057] The device 32 has a transport device 34, which in this case is designed in the form of a conveyor wheel or a transport carousel. The transport device 34 transports the containers 10 in a transport direction 16. In this case, the containers 10 are moved on a circular path by means of the transport device 34.
[0058] The device 32 further comprises a rotation device 36. This is designed to rotate each of the transported containers 10 about a longitudinal axis 20 in a direction of rotation 22. The rotation device 36 is in the form of individual, rotating receptacles 37. Each of the transported containers 10 is arranged in a separate receptacle 37 of the rotation device 36. In other words, each container 10 received in a receptacle 37 is rotated about the respective longitudinal axis 20 by means of the receptacle 37.
[0059] The device 32 further comprises an area-scan camera 12 with a detection area 14. The area-scan camera 12 is arranged immovably (fixed) in this case. In other words, the area-scan camera 12 is not moved, particularly with respect to the transport device 34. In this case, the area-scan camera 12 has a bi-telecentric lens 30.
[0060] The area camera 12, the detection area 14 and the transport device 34 are designed and arranged relative to one another in such a way that the containers 10 are transported through the detection area 14 of the area camera 12 by means of the transport device 34.
[0061] Figure 2 shows a pixel line 26 recorded by the area camera 12. In the illustrated detection area 14 of the area camera 12, a container 10 with a liquid 18 contained therein is completely imaged. The pixel line 26 corresponds in this case to a pixel row (vertical in Figure 2) of the detection area 14. A pixel row refers to pixels (image points) of a vertically oriented row in Figure 2 of the detection area 14. Depending on the position in the detection area 14 at which the container 10 is arranged, the desired pixel line 26 or the desired vertically oriented pixel row in Figure 2 of the detection area 14 of the area camera 12 can be selected. Figure 3 illustrates a method for inspecting
[0062] Containers 10 by means of the device 32 of Figure 1 .
[0063] In Figure 3, the detection area 14 of the area-scan camera 12 is indicated by a dashed rectangle. In this case, the detection area 14 is configured as a rectangular plane.
[0064] In the detection area 14 of the area-scan camera 12, a container 10 is imaged at a first position PI at a time TI. The container 10 is transported in the transport direction 16 (to the left in Figure 3) through the detection area 14 of the area-scan camera 12. The same container 10 is imaged at a later time T2 at a second position P2. The container 10 is rotated about its longitudinal center axis 21 in the direction of rotation 22 during transport through the detection area 14.
[0065] A liquid 18 is contained within the container 10. An (undesired) contaminant in the form of a foreign body 11 is located within the liquid 18 (and thus within the container 10).
[0066] At time TI, the area-scan camera 12 records a pixel line 26 of the container 10 at the first position PI. The pixel line 26 runs along the longitudinal center axis 21 of the container 10 at time TI. The container 10 is transported or moved further in the transport direction 16 by means of the transport device 34, which is only indicated schematically. At time T2, the container 10 has reached the position P2 and, in this case, has rotated completely once (by 360°) around the longitudinal center axis 21.
[0067] Between the time T1 and the time T2, a plurality of pixel lines 26 are recorded by the area scan camera 12. Since the container 10 is moved from right to left (in the transport direction 16) in the detection area 14 of the area scan camera 12 in Figure 3, the corresponding pixel line 26 running through the longitudinal center axis 21 of the container 10 also moves in the transport direction 16. The pixel line 26 therefore moves within the detection area 14 in a similar way to the container 10.
[0068] The pixel lines 26 thus recorded can be reassembled in the chronologically successive order to form a line image 28. Such a line image 28 is schematically illustrated in the bottom of Figure 3. The line image 28 corresponds to the unwound outer surface of the container 10 (cf. the container 10 depicted to the left of the line image 28 in Figure 3).
[0069] The foreign body 11 is particularly clearly visible in line image 28. The container 10 shown can therefore be identified as defective due to the foreign body 11.
[0070] Figure 4 illustrates the method for inspecting containers 10 by means of the device 32 from Figure 1 according to a further embodiment.
[0071] The illustrated embodiment differs from the embodiment shown in Figure 3 in that two containers 10 are imaged at the same time in the detection area 14 of the area-scan camera 12. A first container 13 is imaged at position P1, and a second container 15 is imaged at position P2.
[0072] In this case, two pixel lines 26 are recorded simultaneously. A first pixel line 27 runs along the longitudinal center axis 21 of the first container 13, and a second pixel line 29 runs along the longitudinal center axis 21 of the second container 15.
[0073] Analogous to the exemplary embodiment in Figure 3, the two pixel lines 27, 29 move in the transport direction 16 with the two containers 13, 15. A first line image can then be created from the first pixel lines 27 and a second line image from the second pixel lines 29. Two line images 28 can therefore be created from the first and second pixel lines 27, 29 (not shown). The first line image corresponds to the unfolded outer surface of the first container 13. The second line image corresponds to the unfolded outer surface of the second container 15.
[0074] In this way, two (or more) containers 10 can be inspected simultaneously using the same area camera 12.
Claims
Patent claims Method for inspecting cylindrical containers (10) comprising the steps: Providing an area camera (12) with a detection range (14) , Providing the containers (10) ; Transporting the containers (10) in a transport direction (16) through the detection area (14) of the area camera (12) , Rotating the containers (10) and / or a liquid (18) contained in the containers (10) about a longitudinal axis (20) of the respective container (10) in a direction of rotation (22) while the containers (10) are in the detection area (14) of the area camera (12), Capture at least one sequence of pixel rows (26) by means of the area camera (12), wherein the pixel rows (26) are aligned to a predetermined area of a container (10) or to a predetermined area of a container (10) from different rotational positions of the container (10), wherein the pixel rows are recorded sequentially in time and space. Method according to claim 1, characterized in that at least two sequences of pixel rows (26) are recorded at least partially simultaneously by means of the area camera (12), wherein the pixel rows (26) of each sequence are aligned to a predetermined area of another container (10) or are aligned to a predetermined area of another container (10) from various rotational positions of the respective container (10). Method according to claim 1 or 2, characterized in that the predetermined area of a container (10) onto which the pixel rows (26) of a sequence are aligned is a longitudinal axis (20) of the container (10). Method according to one of the preceding claims, characterized in that at least one row image (28) is created from a recorded sequence of pixel rows (26). Method according to one of the preceding claims, characterized in that the method comprises the step: Aligning the area camera (12), the detection area (14) and / or the transported containers (10) such that the containers (10) remain within the detection area (14) of the area camera (12) for the longest possible time during transport through the detection area (14). A method according to one of the preceding claims, characterized in that the method comprises the step: Providing an optical lens system, in particular at least one telecentric, one bit-telecentric and / or one endocentric lens (30) to reduce image distortion when recording the sequence of to avoid pixel lines (26) using the area camera (12). Method according to one of the preceding claims, characterized in that the method comprises the step: Generating a trigger signal dependent on the movement, in particular the position, of the containers (10), wherein the trigger signal is used to synchronize a sequence of pixel rows (26) with a moving container (10), in particular temporally and spatially. A method according to any of the preceding claims, characterized in that the acquisition of at least one pixel row (26) is carried out by displaying the pixels of the area camera (12) contributing to the pixel row (26) and by hiding the pixels of the area camera (12) not contributing to the pixel row (26). A method according to claims 8 and 7, characterized in that the display and / or hiding of the pixels of the area camera (12) for generating at least one pixel row (26) is synchronized with the movement, in particular the position, of the corresponding container (10) by means of the trigger signal.Device (32) for inspecting cylindrical containers (10) comprising a transport device (34) for transporting the containers (10) in a transport direction (16), at least one rotation device (36) for rotating the containers (10) and / or a Containers (10) with liquid (18) collected about a longitudinal axis (20) of the respective container (10) in a direction of rotation (22), an area camera (12) with a detection area (14), wherein the area camera (12) and / or the transport device (34) are designed and arranged such that the containers pass the detection area (14) of the area camera (12), characterized in that the device (32) is configured to record at least one sequence of pixel lines (26) by means of the area camera (12), wherein the pixel lines (26) are aligned to a predetermined area of a container (10) or to a predetermined area of a container (10) from different rotational positions of the container (10), wherein the device (32) is further configured to assemble the recorded sequence of pixel lines (26) into a line image (28), wherein the pixel lines are recorded temporally and spatially sequentially. become.Device (32) according to claim 10, characterized in that the area camera (12) is arranged immovably in the device (32). Device (32) according to claim 10 or 11, characterized in that the device (32) comprises a lens system, in particular at least one telecentric, one bi-telecentric and / or one endocentric lens (30) , to reduce image distortion when recording a sequence of. to avoid pixel lines (26) using the area camera (12). Device (32) according to one of claims 10 to 12, characterized in that the device (32) is configured to perform a method according to one of the To carry out claims 1 to 9.