Apparatus and methods for product inspection

Abstract

This invention provides an inspection device for verifying the proper sealing of packaging. [Solution] The method comprises the steps of: generating a first substantially two-dimensional fan-shaped beam of light F1 from a first light source L1 located in a first light plane, and generating at least one second similarly substantially two-dimensional fan-shaped beam of light F2 from a second light source L2 located in a second light plane, wherein both light planes are parallel to each other and preferably even identical; positioning a product with respect to the light planes and light sources L1, L2 such that both fan-shaped beams F1, F2 cross the product P along a marking zone H and generate at least one optical marking M on the product within the marking zone; optically detecting the optical marking or a portion thereof using optical detection means K, particularly at least one camera, to determine at least one geometric marking feature of the optical marking; and comparing at least one marking feature with a configurable reference feature corresponding to the marking feature. Multiple light sources generate one or more optical planes, which traverse the container in a marking zone, generating optical markings. These optical markings are detected and evaluated by optical means and compared to corresponding target values.

Description

Technical Field

[0001] The present invention relates to an apparatus and method for inspecting products, particularly bottles and other containers, preferably bottles and other containers with screw caps.

Background Art

[0002] Many industrially manufactured products are stored or filled in containers, such as bottles or canisters. In the food industry, containers are often provided with a seal after filling, and the seal should indicate the integrity of the product. To ensure that the container is properly closed or sealed, it is often necessary to inspect that the closure and / or seal is correctly fitted before the product is released to the market.

[0003] Many containers have an anti-opening seal (also referred to as a sealing ring) attached to the lid below the screw cap, and the anti-opening seal tears or breaks during the first opening. For example, by inspecting an intact anti-opening seal, it can be ensured that the container is properly filled and closed. Hereinafter, the term "closure" shall refer to both the element (cap, lid, etc.) that closes the inside of the container and the anti-opening seal.

[0004] In the prior art, inspection of the closure can be performed, for example, using a camera that detects the closure and then compares the generated image with a preset target value. However, when the closure and the container or bottle have similar colors, the camera can hardly generate or cannot generate an image with sufficient contrast to distinguish the closure from the bottle, which makes evaluation difficult.

Summary of the Invention

[0005] Therefore, the object of the present invention was to provide an improved method for inspecting the container closure and a method for overcoming the aforementioned drawbacks. The above object is solved by the method according to claim 1 and the inspection apparatus described in claim 9. Further advantageous embodiments will become apparent from the dependent claims.

[0006] This invention is based on the understanding that a proper closure is inspected using a substantially two-dimensional image, which generates at least one geometric marking on the closure using at least two substantially two-dimensional fan-shaped beams of light, and the geometric marking is detected and evaluated by appropriate optical means. According to this invention, unlike the prior art, the shape of the two-dimensional marking generated on the closure is evaluated, rather than any color difference or three-dimensional representation of the closure. If the shape corresponds to a reference feature within a settable tolerance, the closure is considered proper; otherwise, the container is considered not properly closed or sealed.

[0007] The method according to this invention includes the following steps. A) A step of generating a first substantially two-dimensional fan-shaped beam of light emanating from a first light source located in a first optical plane, and generating at least one second similarly substantially two-dimensional fan-shaped beam of light emanating from a second light source located in a second optical plane, wherein both optical planes are parallel to each other, and preferably even identical. B) A step of positioning a product relative to a light plane and a light source such that at least one fan-shaped beam of light crosses the product along the marking zone and generates a light marking on the product within the marking zone. Using the first light source, a first substantially two-dimensional fan-shaped beam of light is emitted, which is suitable for generating a two-dimensional marking on an object when the first light plane crosses the object. The same applies to the second light source. The two light sources are preferably used to illuminate the closure to be inspected as far around its circumference as possible. To this end, it is preferable that the two light sources be positioned so that the product or closure to be inspected is located between the two light sources and the entire closure is illuminated from as far around its circumference as possible. C) A step of optically detecting the light marking or a portion thereof using optical detection means, particularly at least one camera, and determining at least one geometric marking feature of the light marking. In this process, the optical marking generated on the closing portion is first detected using optical means. The optical means is, in particular, a camera combined with image recognition means, which can be used to identify one or more marking features that characterize the detected optical marking. The marking features may be, in particular, geometric features that characterize the spatial shape of the marking. D) A step of comparing at least one marking feature with a configurable reference feature corresponding to that marking feature.

[0008] In the final step of this method, at least one marking feature is compared to a reference feature assigned to that marking feature. This reference feature may be stored in an appropriate storage means for each product to be inspected for comparison. If the detected marking feature matches the reference feature within a settable tolerance, the product, for example, its closure, can be classified as good; if it does not match, each product may be sorted and removed from the product flow as necessary.

[0009] The marking features can also include the relative positions of individual parts of the optical marking. For example, a marking feature can be formed from the radial distance of a particular marked portion relative to a assumed vertical central axis at the center of the product, in order to determine the roundness of a closure or at least a portion thereof. If this distance deviates beyond the allowable tolerance from the assigned target distance, it can be evaluated as an indication of a defective closure.

[0010] One or more fan-shaped beams of light produce thin, sharp, and sufficiently contrasting markings in the form of points or lines on the closure, which can be easily optically distinguished from the closure itself or from areas adjacent to it. The markings have the advantage of allowing very precise inspection of relatively narrow areas on the closure compared to a planar image of the closure region. By selecting the appropriate wavelength of light within the fan beams, the contrast can be advantageously adjusted or improved. In contrast, in the prior art, selecting the light color is of little use because a three-dimensional area is always illuminated or detected without a sharp optical boundary.

[0011] Some or all of the light planes are positioned to overlap, preferably coincide with each other, by having their corresponding light sources generate their fan-shaped beams in the same plane. In this case, they generate a single two-dimensional light plane. This provides the advantage that, with proper arrangement of light sources, the closure to be inspected is illuminated from all sides, and the light marking has the shape of a substantially closed curve or a curve formed from individual points encircling the product, e.g., its closure. In this way, a complete image of the geometry of the closure can be generated with particular certainty where the fan-shaped beams generated collectively by all the light sources cross the product or closure.

[0012] As an extension of the above considerations, in a further advantageous embodiment of the present method, it is intended that at least two, preferably all, optical planes are oriented parallel to a reference plane (here again, some or all optical planes may be positioned to coincide with each other and overlap, thereby forming a common or, as a whole, single optical plane). The reference plane is then defined by, for example, a mounting surface formed on the underside of the product, which may be, for example, the bottom of a bottle or canister. If the bottle or canister is placed on a flat surface at its bottom, that surface corresponds to the reference plane.

[0013] Alternatively or supplementally, the reference plane may be formed by a conveying plane on which the product is conveyed before, during, or after the method. That conveying plane may be, for example, the upper surface of a conveying belt on which the product is conveyed.

[0014] By positioning one or more light planes parallel to a reference plane, a special advantage is gained: the positioning of the product relative to the light source only needs to be controlled or set in terms of height (i.e., perpendicular to the reference plane in the height direction Z). As long as the height is precisely adjusted to the closing part to be inspected, the lateral position of the product within the light plane (in the horizontal directions X and Y) is irrelevant, because a light plane parallel to the reference plane always crosses the closing part at the same height, regardless of its XY position. This eliminates the need for costly and precise XY positioning of the product relative to the light source, as long as the marking zone is located within the fan-shaped light.

[0015] In a further advantageous embodiment of the present method, multiple optical markings are intended to be generated and evaluated at different locations on the product. For example, in addition to the roundness of the lid, other shapes of the bottle may also be inspected. This is preferably done automatically. For example, the closure can be inspected at different Z heights by having one optical plane sequentially traverse the closure at different heights, or by having multiple optical planes traverse the closure simultaneously. For example, it is possible to inspect whether the tamper-evident seal is properly installed and the precise shape of the portion of the closure separated from the tamper-evident seal. However, it is also conceivable that another fan-shaped beam of light may be directed at the product at different angles, and the optical markings generated in each case may be detected and compared to target values.

[0016] According to a further advantageous embodiment of this method, the position of the optical marking on the product, the orientation of the fan-shaped light, or the type of optical marking may be selected by an operator or automatically, particularly depending on the product itself. For example, for the inspection of a particular tamper-evident seal, fan-shaped light can be automatically set to produce an optically detectable optical marking on the seal. Setting the method parameters can be done, for example, using a control unit that controls individual light sources. Depending on the product type, the method parameters can be set manually or automatically, for example, by automatically reading an identifier attached to the product and setting the parameters accordingly.

[0017] The two-dimensional fan-shaped light emitted from a light source and the resulting light plane can be characterized by various method parameters, only a few of which are listed below.

[0018] - The fan-shaped light may consist of individual rays, each ray either spaced apart from or at an angle to one another. In this case, the light markings consist of individual points generated on the product by each ray, in the form of regularly interrupted lines. Depending on the number and density of the points, they allow for sufficiently accurate information about the geometric shape of the closing part.

[0019] - The fan-shaped light may form a substantially continuous optical plane through a number of individual rays. In this case, the optical marking occurs as a substantially continuous line on the closure, and this line provides particularly good information about the geometric shape of the closure.

[0020] - The wavelength of light emitted from the light source may be within the visible or invisible region. The important thing is that the optical markings generated by each type of light can be detected by optical recognition means.

[0021] - Each fan-shaped light or each light plane is formed substantially two-dimensionally, i.e., has a negligible thickness, but its thickness can be intentionally set in order to generate an optically well-detectable light marking. The thickness is preferably less than 1 mm.

[0022] Depending on the properties of the closure, the resulting light marking may have a radial depression or an expansion, for example, when the light plane intersects the connecting web between the tamper-evident seal and the lid or the empty space located therebetween.

[0023] According to a further advantageous embodiment of the method, the inspection of the closure can also be carried out while the product is moving relative to the light source. For example, a bottle or a canister as the product can be conveyed on a conveyor belt and can be moved into or through the action area of one or more light planes during this process. Thereby, the inspection of the closure can be carried out during conveyance. Especially in that case, the advantage of the light plane parallel to the reference plane (i.e., the conveyor belt) according to the present invention is shown. This light plane always crosses the closure or generates a light marking thereat at the same height position regardless of the conveyance position of the product.

[0024] The optical detection means preferably includes a perimetric camera. In such a camera, the optical path is a convergent optical path rather than a divergent one. Thereby, it is possible to observe an object simultaneously from a plurality of directions through one objective lens. In that way, for example, a single perimetric camera arranged above the closure can completely detect the light marking formed over the entire circumference of the closure without the need for a plurality of cameras. Thereby, the computational load is reduced and the synchronization of a plurality of cameras that would normally be required is avoided.

[0025] At least one light source is preferably formed as a line laser. Such a laser, which is known per se to those skilled in the art, preferably generates a quasi-continuous fan-shaped light, thereby further generating a continuous light marking on the closure, and the light marking can be evaluated particularly accurately.

[0026] According to the present invention, the shape of the closure in the marking zone, which is partially or fully determined using optical marking, is compared with reference features that may, for example, be stored in a control unit. Preferably, the reference features are based on the assumption that the optical marking is elliptical or, as a special case of an ellipse, circular. A circular optical marking typically indicates that the closure is properly formed and, for example, is not obliquely seated on the closure thread of a bottleneck. If the optical marking is recognized as circular in the region of the anti-opening seal, the proper sealing of the container can be inferred. In contrast, if the optical marking shows an irregular deviation from circularity, this can be evaluated as an indication of a closure that is not properly attached.

[0027] The device for implementing the method according to the present invention includes at least the following components.

[0028] a) A first light source for generating substantially two-dimensional fan-shaped light in a first light plane and at least one second light source for generating substantially two-dimensional fan-shaped light in a second light plane. Both light planes are positioned parallel to each other and preferably further form a single integrated light plane.

[0029] b) Optical detection means for optically detecting the optical marking generated by at least one light source within a marking zone on the product to be inspected. The marking zone is preferably located in the region of the container closure or the region of the anti-opening seal (usually associated therewith).

[0030] c) An evaluation unit, which may be part of a control unit, and is formed to compare at least one geometric marking feature of the detected optical marking with a reference feature assigned to that marking feature. The reference feature can be stored in the evaluation unit for this purpose or, for example, is accessible to the evaluation unit by accessing a local or higher-level storage device.

[0031] The positions of at least two light sources and / or optical detection means are preferably automatically or manually set relative to the product, depending on the product to be inspected. This setting can be done using a control unit that controls the light sources with appropriate method parameters. For example, the light sources may be automatically movable and oriented via appropriate drive devices, thereby allowing the fan-shaped light emitted from each light source to be positioned in terms of position and direction of emission.

[0032] The light sources are preferably positioned relative to each other so as to form a regular geometric shape, particularly a circle, that is assumed to be concentric with respect to the product in the light plane at the time of inspection. At least two light sources are preferably facing each other with respect to the product located between them, thereby ensuring circumferential illumination of the marking zone. Particularly uniform illumination can be achieved, for example, by positioning the light sources at approximately equal distances from the product and / or by evenly distributing the light sources around the product. Further between the light sources and laterally to the product, processing means for processing the product may be positioned, for example, for labeling or scanning specific markings on the product.

[0033] The inspection apparatus according to this invention can be combined with a conveying device, which is configured to convey the products to be inspected into the operating area of ​​the light source, and to perform inspection during or immediately thereafter (start-stop operation). Alternatively or supplementally, it may also be intended to further convey the products after inspection. Depending on the inspection, products may also be sorted and removed from the product flow at that time.

[0034] Preferably, the conveyor belt of the conveying device forms a reference plane on which the product to be inspected can be conveyed, and at least one light source is positioned on each side of the conveying path so that the product moves between the two light sources during conveyance.

[0035] An inspection device according to the present invention may also be conceivable in which at least two light sources and optical detection means are jointly arranged on a robot-assisted inspection head, preferably. In this case, the components can be jointly and relative to the product to be inspected, and preferably automatically positioned. This allows different products, and preferably different marking zones, to be inspected quickly and automatically.

[0036] Although the inspection of the container closure portion was described above, the method and corresponding apparatus according to the present invention can also be used to inspect other areas of the product, and inferences can be drawn about the condition of the product from the shape of the optical markings generated in such other areas.

[0037] Hereinafter, one embodiment of the present invention will be described in more detail with reference to the drawings. [Brief explanation of the drawing]

[0038] [Figure 1] This is a schematic side view of the arrangement of an inspection device with a conveying device according to the present invention. [Figure 2] This is a schematic plan view of the arrangement shown in Figure 1. [Modes for carrying out the invention]

[0039] Figure 1 shows a side view of the conveying device T in the lower region. The conveying belt, which is not shown in detail by its reference numerals, is on the reference plane E by its surface. B The product, standing on the reference plane, is moved along the transport path W in the transport direction X using a transport device T.

[0040] Figure 2 shows that four light sources L1 to L4 are arranged horizontally above the conveying device, spaced apart from each other, and that each of these light sources emits substantially two-dimensional fan-shaped light F1 to F4 toward the center where the product P to be inspected is located. It can be seen that all light sources are positioned laterally with respect to the conveying path W so that the product P can be conveyed through the light sources without being obstructed by obstacles.

[0041] All fan-shaped rays F1-F4 are on the reference plane E. B The light sources extend parallel to each other at the same Z height, thereby occupying a common light plane E. The fan-shaped light traverses the product P, formed as a bottle, along the marking zone H in the area of ​​the lid D of product P, thereby generating a light marking. In the illustration, the light marking M is generated in the area of ​​the tamper-evident seal, which is not specifically identified, at the lower end of the lid D. Using four light sources evenly spaced around product P, a continuous light marking M can be generated around the entire circumference of the product within the marking zone H. Theoretically, two light sources positioned opposite each other would already suffice to achieve sufficient omnidirectional illumination of the marking zone.

[0042] A pericentric camera K is positioned approximately above the center of product P, and this pericentric camera K can detect the optical marking M generated within the marking zone H around the entire circumference of the lid.

[0043] Camera K, light sources L1-L4, and transport device T are controlled by a common control unit C. Control unit C evaluates the optical markings M detected by camera K and compares these optical markings M with one or more appropriate target values. These target values ​​are stored in a memory device not detailed in the control unit C.

[0044] To implement the method according to the present invention, product P is positioned relative to light sources L1 to L4 such that the fan-shaped light generated by the light sources crosses the marking zone H where product P is to be inspected, thereby generating a light marking M there. This can be done, for example, while product P is being transported on a conveyor belt of a conveying device T, passing between light sources L1 to L4. The conveyor belt may be stopped during inspection.

[0045] At at least one configurable point in time, camera K detects the optical marking and transmits the generated data to control unit C. The data is then evaluated with respect to at least one marking feature and compared to at least one corresponding target value in order to inspect the proper condition of the lid D or generally the closing part of product P. [Explanation of Symbols]

[0046] C Control Unit D Lid E light plane E B Reference plane F1-F4: First to fourth fan-shaped beams H marking zone L1~L4: 1st to 4th light sources K Optical detection means M Light Marking P product T Transport device W Conveyor path X: Conveying direction, horizontal longitudinal direction Y horizontal direction Z (height direction)

Claims

1. A method for inspecting a product (P), particularly a container, comprising the following steps: A) A step of generating a first substantially two-dimensional fan-shaped beam of light (F1) emanating from a first light source (L1) located in a first light plane (E1), and generating at least one second similarly substantially two-dimensional fan-shaped beam of light (F2) emanating from a second light source (L2) located in a second light plane (E2), wherein both light planes (E1, E2) are located parallel to each other, and preferably even identical; B) The step of positioning the product (P) with respect to the light plane (E1, E2) and the light sources (L1, L2) such that both of the fan-shaped lights (F1, F2) cross the product (P) along the marking zone (H) and generate at least one light marking (M) on the product (P) within the marking zone (H), C) A step of optically detecting the optical marking (M) or a part thereof using optical detection means (K), particularly at least one camera, and determining at least one geometric marking feature of the optical marking (M), D) A method comprising the step of comparing at least one of the marking features with a configurable reference feature corresponding to the marking feature.

2. At least two, preferably all, of the aforementioned light planes (E1, E2, etc.) are reference planes (E Ｂ It is oriented parallel to the reference plane (E Ｂ )teeth, a) A mounting surface formed on the lower surface of the product (P), and / or b) A transport plane on which the product (P) is transported, The method according to claim 1, characterized in that it is formed by

3. The method according to claim 1 or 2, characterized in that the optical marking (M) encircles the entire circumference of the product (P) as a substantially closed line.

4. The method according to any one of claims 1 to 3, wherein a plurality of the optical markings (M) are generated and evaluated at different height positions on the product (P).

5. The method according to any one of claims 1 to 4, wherein the height position of the light marking (M) and / or the orientation of the fan-shaped light (F1, F2) and / or the type of light marking on the product (P) is set in particular according to the product (P) itself.

6. During inspection, relative motion occurs between the product (P) and at least one of the light sources (L1, L2), and / or the product (P) is preferably in reference plane (E Ｂ The method according to any one of claims 1 to 5, wherein the transport is carried along the )

7. a) The optical detection means includes a pericentric camera, and / or b) At least one of the light sources (L1, L2, etc.) is a line laser, and / or c) In the marking zone, the wavelength of light generated by at least one of the light sources (L1) is selected according to the characteristics of the product (P) to be inspected, particularly the surface or surface color of the product (P) in the marking zone, in order to generate a contrast between the optical marking (M) and the product (P) that can be detected as well as possible by the optical detection means. The method according to any one of claims 1 to 6.

8. The method according to any one of claims 1 to 7, wherein one, more, or all of the criterion features described in claim 1(D) are based on the optical marking (M) being elliptical, particularly circular.

9. An inspection apparatus for carrying out the method described in any one of claims 1 to 8, a) comprising a first light source (L1) for generating a first substantially two-dimensional fan-shaped beam of light (F1) in a first light plane (E1), and at least one second light source (L2) for generating a second substantially two-dimensional fan-shaped beam of light (F2) in a second light plane (E2), wherein both light planes (E1, E2) are located parallel to each other and preferably even identical, b) Optical detection means (K) for optically detecting a light marking (M) generated on a product (P) to be inspected by at least one of the light sources (L1, L2, etc.), c) An evaluation unit (C) is configured to compare at least one geometric marking feature of the detected optical marking (M) with a reference feature assigned to the marking feature, wherein the reference feature is storable in the evaluation unit or available to the evaluation unit, An inspection device equipped with the following features.

10. The inspection apparatus according to claim 9, wherein the height positions of at least two of the light sources (L1, L2) and / or the optical detection means (K) can be set automatically or manually relative to the product (P) to be inspected.

11. The inspection apparatus according to claim 9 or 10, wherein the light sources (L1, L2, etc.) used to generate each of the fan-shaped lights (F1, F2, etc.) are arranged relative to each other at the time of inspection in a regular geometric shape, particularly on a circle, assumed to be concentric with respect to the product (P) within the light plane (E1, E2, etc.), preferably facing each other in pairs, and very preferably having a constant distance from each other in the circumferential direction.

12. An arrangement of an inspection device and a conveying device (T) according to any one of claims 9 to 11, wherein the conveying device (T) carries the product (P) to be inspected a) Transport the product into the operating area of ​​the light source (L1, L2, etc.) and perform the inspection during the movement or during a temporary product stoppage. and / or b) Further transport the product (P) after inspection. Arrangement that is formed in such a way.

13. The transport path (W) of the transport device (T) is on the reference plane (E Ｂ ) forms the reference plane (E Ｂ The arrangement according to claim 12, wherein the product (P) to be inspected is transportable along the transport path (W) in the transport direction (X) before, during, or after inspection, and at least one light source (L1, L2, etc.) that generates a light plane (E) is positioned on each side of the transport path (W) such that the product (P) moves between both of the light sources (L1, L2) while being transported.

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