Inspection device and method

Abstract

In a method for reading a code (K) arranged on a wall (2) of a container (1), an illuminated region (15) is generated on the container wall using a light source (13). The width (B) of the illuminated region (15) in the circumferential direction (U) of the container (1) is smaller than the width (b) of the code surface area (4). In connection with a relative movement between the container (1) and the illuminated region, a series (S) of individual images (E) of the illuminated region (15) is captured by means of a matrix camera (19), and an image of the code (K) is assembled from the series of individual captured images (E). The invention also relates to a device (10) for reading a code (K) arranged on the wall of a container (1).

Description

[0001] Inspection device and procedure

[0002] The invention relates to a method for reading a code arranged on a vessel wall, which code occupies a code area on the vessel wall. The invention also relates to a corresponding device.

[0003] A method and device for reading a code occupying a coding surface on a vessel, in particular a bottle or other glass container, is disclosed in EP 2 297 672 B1. EP 2 297 672 B1 emphasizes that the surface of the code is completely covered by the illumination of the light source during a recording so that all parts of the code can be read. US 2006 / 0091214 A1 discloses an arrangement for optically reading two-dimensional graphic codes from a surface, but has no particular reference to vessels. US 4,644,151 describes the optical reading of a code extending in two lines around the lower end of a side wall of vessels. A camera with a linear array of light-sensitive elements is used to read the code, by means of which the light intensity reflected by individual coding elements can be measured.

[0004] Based on EP 2 297 672 B1, the object is to develop a method and a device for reading a code on the wall of a vessel, which is as efficient, as reliable, as broad in its field of application and as simple to adjust as possible, and which additionally avoids the disadvantages of a large extension of a light source, which conflicts with the confined space conditions in a typical operating environment.

[0005] This object is achieved by a method having the features of claim 1 or by a device having the features of claim 9. Advantageous developments of the invention are specified in the dependent claims.

[0006] The method according to the invention provides that an illuminated area generated on the (particularly curved) wall of the vessel, e.g., a bottle or other container made of glass, has a smaller width in the circumferential direction of the vessel than the width of the coding surface. Thus, the invention deviates from the objective of EP 2 297 672 B1 of always illuminating the entire surface of the coding surface.

[0007] In the context of the invention, the term "illumination area" is understood to mean the area on the surface of the vessel in or from which light rays emanating from the light source are reflected onto the camera. The size of the illumination area is thus determined by the extent of the light source, the curvature of the vessel's surface and, if applicable, the opening of an aperture in the beam path. The extent of this illumination area can be limited or reduced by a smaller extent of the light source, a greater curvature (i.e., smaller radius of curvature) of the vessel's surface and, if applicable, by reducing the size of the opening of an aperture in the beam path. In the case of a vessel with a flat side wall, its "radius of curvature" is infinite.

[0008] The light emitted by the light source can and may be diffuse to a certain degree. The illumination area therefore does not necessarily have an absolutely sharp boundary. In the context of the present invention, the "width" of the illumination area is generally understood to be the FWHM (full width at half maximum) of the illumination intensity (still captured by the camera) in the respective spatial direction. In the case of a vessel with a curved side wall, a sharply defined light edge can appear in the camera image - namely where the light coming from the light source is deflected so strongly laterally by the vessel wall that it shines past the camera.

[0009] In the invention, a relative movement, preferably a translational and / or rotational relative movement, is generated between the vessel and the illumination region, and a series of individual images of the illumination region is acquired using a matrix camera, wherein a relative movement occurs between the vessel and the illumination region between individual images of the series. Subsequently, or possibly still during the recording of the series of individual images, a (digital or virtual) image of the coding is compiled from the individual images. For example, subsequently, or possibly still during the recording of the series of individual images, a search is made for elements of the coding in the individual images, a virtual version of the complete coding is generated in memory from these elements, and once completed, the coding is read out. The image of the coding can be stored digitally and read out separately.Alternatively, simply assembling the image of the coding can be equivalent to reading the coding.

[0010] The invention offers various advantages. In the invention, the area of ​​the illumination region is limited to a comparatively narrow width. This has the advantage that the light output is particularly high, so that either a high light intensity is achieved or, on the other hand, a less powerful but particularly (energy-)efficient light source can be used. Since the speed required for detecting the coding also requires a high movement speed, it is particularly advantageous if the exposure time of the individual images can be particularly short in order to largely prevent motion blur during the image capture. A short illumination duration with high light intensity, for example a flash light, is well suited for this.

[0011] Combining an image of the code from a series of individual images has the advantage that the inspection of the code becomes independent of its actual size. In other words, the invention allows codes with very different sized coding areas to be read without requiring an adjustment of the illumination width, as is the case with conventional methods. The matrix camera used enables such image composition. The matrix camera should preferably have the ability to capture individual images at a very high frequency of several hundred or thousand Hertz.

[0012] Transparent or translucent containers, such as those made of glass, are particularly suitable for containers with a code affixed to their walls. These containers can also be bottles.

[0013] Preferably, the coding is formed as an arrangement of elevations and / or depressions in the vessel wall. The elevations or depressions can be essentially point-shaped. It is sufficient if the reflectivity or transmissivity of the vessel wall at the location of the elevation or depression differs from that of the adjacent areas of the wall. Deflection of the light incident from the illumination by the elevation or depression, such that the light does not enter the camera and appears correspondingly dark against a bright background created by the light source, is also suitable for detecting the coding.

[0014] Preferably, the coding is formed as a matrix-like arrangement of such elevations and / or depressions, ie as an arrangement of n*m pixels, as disclosed in a similar manner in EP 2297 672 B1 and hereby incorporated by reference.

[0015] Preferably, at least one individual image in the series, preferably all individual images in the series, overlap with a respective adjacent individual image. This facilitates the assembly (and reading) of an image of the coding from the series of individual images. Structures or individual regions of the coding that are found in the adjacent individual images allow the precise assembly of the overall image. For example, it is conceivable for adjacent individual images to overlap with an adjacent individual image by up to 30%, preferably up to 40%, or even up to 50% (or more) of their respective individual area.

[0016] It may be useful for the illumination area to be strip-shaped. If the vessel being examined has an axial direction, the strip can have its greatest extent in the axial direction of the vessel or parallel to this axial direction. Alternatively, the illumination area can have its smallest extent in the circumferential direction of the vessel, i.e., in the direction of relative movement between the vessel and the illumination area.

[0017] In one spatial direction, preferably transverse to the circumferential direction of the vessel, the illumination area preferably has a length at least as large as the corresponding dimension of the coding area. This has the advantage that the coding image only needs to be assembled "one-dimensionally" from the series of individual images, i.e., a scan is performed in only one spatial direction.

[0018] The illumination area should preferably have a maximum width of 7 mm along the circumference of the vessel (provided this is still smaller than the width of the coding area along the circumference of the vessel). This allows the illumination to be concentrated on a very narrow area.

[0019] It is even more preferred if the illumination area in the circumferential direction of the vessel has a width of only 3 mm to 6 mm, preferably a width of 4 mm to 5 mm. This may be sufficient to cover a coding with a coding area of, for example, 8 x 8 mm with a comparatively small number of individual images.

[0020] It can be advantageous if the relative movement between the vessel and the illumination area occurs continuously while the series of individual images is being captured. This has the advantage of avoiding repeated deceleration and acceleration of the vessel, which speeds up the reading of the code. In an alternative variant, the relative movement between the vessel and the illumination area occurs intermittently between each two individual images in the series. This variant has the advantage that the vessel remains stationary during the capture of an individual image, thus improving the image quality of the virtual version of the code by eliminating motion blur in the images.

[0021] In each of the above-mentioned variants, the relative movement between the vessel and the illumination area can be generated, for example, by a rotation of the vessel about an axis and / or by a translational movement.

[0022] If the vessel is already axially symmetric, such as a bottle, the rotation axis of the relative movement can be the vessel's axis. To generate the relative movement, the vessel can be placed, for example, on a turntable or in a star wheel of an inspection module (e.g., a glass forming machine). Additionally or alternatively, the vessel can be gripped and rotated by a gripper device. A translational movement can be generated by arranging the vessel, the turntable, or the star wheel on a translation table driven by a motor (e.g., a stepper or servo motor).

[0023] The invention also relates to a device for reading a code arranged on a wall of a vessel, wherein the device comprises a light source for generating an illumination region on the vessel and a camera for recording individual images. According to the invention, a matrix camera is used as the camera, and the light source—with the vessel inserted into the device—is configured to generate an illumination region on the vessel that has a maximum width of 7 mm in a circumferential direction of the vessel. The device further comprises an evaluation unit configured to compose an image of the code from a series of individual images. The use of a matrix camera and a light source with a very narrow width of the illumination region generated by it compared to the prior art offers the advantages explained above. The evaluation unit can be part of a computer device.The computer device can be designed as a controller of the device.

[0024] Preferably, the light source is configured to generate a strip-shaped illumination area on the vessel. Such a strip-shaped illumination area has the advantage that a one-dimensional, i.e., linear, scan allows for particularly simple assembly of the overall image of the coding.

[0025] Preferably, the light source is configured to generate an illumination area on the vessel that has a width of 3 mm to 6 mm in a circumferential direction of the vessel, even more preferably a width of 4 mm to 5 mm. These dimensions have proven particularly advantageous for reading codes with typical coding areas of up to 8 x 8 mm or 10 x 10 mm with a comparatively small number of individual images.

[0026] It is advantageous if the illumination area transverse to the circumferential direction of the vessel, ie preferably parallel to an axial direction of the vessel, has a length which is at least as large as a dimension of the coding area in the corresponding spatial direction.

[0027] The device expediently comprises a drive for generating a relative movement between the vessel and the illumination area. For this purpose, the light source or a lighting arrangement could be moved around the vessel. However, it has proven more advantageous to generate a rotational movement of the vessel. To achieve this, the vessel can be arranged, for example, on a turntable or in a star wheel belonging to an inspection machine, or it can be gripped and rotated by appropriate rotatable grippers.

[0028] In a further development, the device comprises a variable aperture for changing the width of the illumination area in the circumferential direction of the container. This offers the advantage of being able to easily adapt the device to different container sizes or different coding shapes and to influence the width of the illumination area (or strip).

[0029] It can be beneficial if the light source has a contrast-enhancing filter. This improves the quality of the images and makes it easier to read the code.

[0030] The method or device can be used, for example, in a star wheel of a testing machine, which in turn can be part of a glass forming machine or downstream of it. An advantageous embodiment of the invention is explained in more detail below with reference to a drawing. In detail:

[0031] Fig. 1 shows a representation of a vessel to be inspected with a coding,

[0032] Fig. 2 is a schematic side view of an embodiment of a device according to the invention,

[0033] Fig. 3 is a plan view of the device according to Fig. 2,

[0034] Fig. 4 a schematic representation to understand the “illumination area” and

[0035] Fig. 5 is a schematic representation of the overlap of a coding with a series of individual recordings.

[0036] Matching components are provided with the same reference numerals throughout the figures.

[0037] Fig. 1 shows a vessel 1 to be inspected. The vessel 1 can, but need not, be transparent or at least translucent, for example, made of glass or plastic. It can be bottle-shaped, for example, rotationally symmetrical with an axis of symmetry A. However, the vessel 1 can also have cross-sections other than circular, for example, elliptical or polygonal.

[0038] The vessel 1 has a wall 2 and a base 3. A coding K is provided on the wall 2 of the vessel, occupying a coding surface 4. The coding surface 4 has a width b in a circumferential direction U of the vessel 1 and a height h parallel to the axial direction A of the vessel 1. The width b and the height h can each be between 7 mm and 12 mm, for example, 8 mm or 10 mm each.

[0039] The enlargement of the coding K in Fig. 1 shows that the coding K is formed from a matrix-like arrangement of individual coding elements 5. The individual coding elements 5 are produced as an elevation or a depression in the wall 2 of the vessel 1, for example during the formation of the vessel 1 in a glass forming machine. Alternatively, the coding can also be applied after the actual glass forming, for example by being generated using high-energy laser radiation. Each individual coding element 5 is dimensioned such that at its location the extent of the reflectivity and / or transmissivity of the wall 2 of the vessel 1 differs significantly from the regions of the vessel wall 2 without such a coding element 5.

[0040] Fig. 2 shows a schematic side view of a device 10 according to the invention for reading a code K on the wall 2 of the vessel 1. The device 10 has a turntable 11 or a star wheel 11, on or in which the vessel 1 to be inspected can be arranged. The turntable / star wheel 11 can be driven to rotate by means of a drive 12, for example a servo drive. Preferably, an axis of the rotational movement of the turntable 11 coincides with the axis of symmetry A of the vessel 1. As an alternative to a turntable 11, a movement of the vessel 1 within the device 10 can be generated in any other way, for example translationally instead of or in addition to a rotational movement.

[0041] A light source 13 generates light which is collimated by an aperture 14 onto an illumination area 15 on the wall 2 of the vessel 1. The illumination area 15 has a width B in the circumferential direction U of the vessel 1 which is smaller than the width b of the coding area 4. In the circumferential direction U of the vessel 1, consequently, not the entire width b of the coding area 4 is covered by the illumination generated by the light source 13.

[0042] One or more additional optical elements 17 can optionally be located in the beam path 16 of the light generated by the light source 13, for example a diffuser (for generating a more uniform, homogeneous light distribution) 17 and / or a contrast-enhancing filter 17.

[0043] The device 10 further comprises a camera 19, which is specifically designed as a matrix camera 19, i.e., a camera with a matrix-like, two-dimensional arrangement of light-sensitive elements (or pixels). A field of view 20 of the camera is directed onto the vessel 1 and is large enough to cover at least the illumination area 15, preferably even large enough to cover the entire coding area 4. However, the field of view 20 of the matrix camera 19 could also be selected to be narrower, even narrower than the width B of the illumination area 15. A beam splitter 19a is arranged such that, at the location of the vessel 1, the beam path 16 of the light generated by the light source 13 and the field of view 20 of the camera 19 are at least substantially coaxial with one another. In the illustrated embodiment, the path of the rays from the vessel 1 to the camera 19 is substantially horizontal or perpendicular to the axis A of the vessel 1.The light source 13 is arranged above this path and, in this embodiment, emits its light vertically downward until it is redirected by the beam splitter 19a. Alternatively, the positions of the light source 13 and the camera 19 could be swapped.

[0044] A telecentric optic 19b is integrated into the camera 19 or arranged upstream of it, so that the field of view 20 of the camera 19, i.e., the beam path of the light captured by the camera 19, runs at least largely parallel between the vessel 1 and the telecentric optic 19b. In the case of a vessel 1 with a curved side wall (as shown), for example, a glass bottle, the camera 19 thus captures the full height of the illumination from the light source 13, while the width B of the captured area of ​​the illumination surface 15 is further limited by the curvature of the vessel wall and the resulting lateral deflection of the light rays. Details regarding the limitation of the illumination area 15 will be explained below with reference to Fig. 4. A computer device 21 controls the operation of the device 10.It has an evaluation unit 22 configured to compile an entire image of the coding K from individual images captured by the matrix camera 19 or to read the coding. The computer device 21 can have a memory for storing individual images or composite digital or virtual images of the coding K. The computer device can be operatively connected to the light source 19, the drive 12, and the matrix camera 19 in order to control and coordinate these components of the device 10.

[0045] Fig. 3 shows the device 10 according to Fig. 2 in plan view. It can be seen here that the light source 13 and the aperture 14 arranged in front of it are arranged above the light path between the vessel and the telecentric optics 19b. The width of the detected or illuminated area of ​​the illumination surface 15 is indicated by B, and the width of the coding K is indicated by b. Preferably, the axis A of the vessel 1 coincides with the axis of the turntable 11 so that the position of the outer surface of the vessel 1 does not change as much as possible during the rotation of the vessel 1.

[0046] With reference to Fig. 4, it can be understood how the term "illumination area" is to be understood in the context of the invention. Schematically—and in particular independently of their actual geometric arrangement—the vessel 1, the light source 13, and the matrix camera 19 are shown in Fig. 4. In the present example, the vessel 1 has a convexly curved outer surface with a radius of curvature R around the axis A of the vessel 1. A coding surface 4 on the surface of the vessel 1 contains the coding K. In the circumferential direction U of the vessel 1, the coding surface 4 has a width b.

[0047] Light falling from the light source 13 onto the vessel 1 is reflected at the surface of the vessel 1 according to the rule "angle of incidence = angle of reflection" before reaching the matrix camera 19. Fig. 4 shows the outer edge rays 16a of the light emitted by the light source 13, which just reach the matrix camera 19. The outer edge rays 16a are determined by the respective distances between the light source 13, the aperture 14 and the vessel 1, by the lateral extent of the light source 13 and the aperture

[0048] 14 and by the radius of curvature R of the wall 2 of the vessel 1. The illumination area

[0049] 15 is now the area on the vessel 1 which is delimited by the marginal rays 16a. In other words: the illumination area 15 is the area on the surface of the vessel 1 from which light from the light source 13 is reflected onto the matrix camera 19. The size of this illumination area 15 in the circumferential direction of the vessel 1 is defined by the extent of the light source 13, the size of the opening in the aperture 14, the respective distances between the light source 13, the aperture 14 and the vessel 1, and by the radius of curvature R of the surface of the vessel 1. If, for example, the curvature of the surface of the vessel 1 becomes smaller, i.e. the radius of curvature R becomes larger, the width B of the illumination area 15 would also increase. In order to keep the width B of the illumination area 15 constant or to limit it, the extension of the light source 13 or - preferably - the opening width of the aperture 14 would have to be reduced as a countermeasure.The method and the device according to the invention are designed under these conditions such that the width B of the illumination region 15 on the vessel 1 is smaller than a width b of the coding surface 4 in the circumferential direction U of the vessel 1. Preferably, the illumination region 15 in the circumferential direction U has a width B of a maximum of 7 mm or of only 3 - 6 mm.

[0050] Fig. 5 shows schematically how the coding K on the vessel is read out in the method according to the invention or with the device 10 according to the invention. In order to obtain an image of the entire coding, a series S of individual images is generated by means of the matrix camera, wherein the individual images E of the series S are arranged and dimensioned such that they altogether cover the coding area 4 of the coding K. Each individual image E is two-dimensional, since the camera is a matrix camera 19. The individual image E has a width and a height H. However, the area that can be used to read out the coding K is limited by the illumination area 15 that is generated by the light source 13 on the wall 2 of the vessel 1. For better understanding, Fig. 5 therefore only shows the optically evaluable area for each individual image E, which corresponds to the illumination area 15 and thus has a width B and a height H.The height H of the strip-shaped illumination region 15 in the exemplary embodiment can be greater than the height h of the coding area 4, while the width B of the illumination region 15 is smaller than the width b of the coding area 4 in the circumferential direction U of the vessel. For example, the width B of the illumination region 15 can be from 4 mm to 6 mm, preferably 5 mm, if the coding K occupies a coding area 4 of 8 x 8 mm.

[0051] In Fig. 5, the coding area 4 is covered with a series S of a total of six individual images E. However, this number can be freely selected depending on the type of matrix camera 19 used, the size of the coding area 4 or the type of vessel 1. For example, a series S can have between five and one hundred individual images E.

[0052] Between the recording of two adjacent individual images E, a relative movement takes place between the illumination region 15 and the vessel 1 in the circumferential direction U of the vessel 1. This relative movement can, for example, be selected to be so large that two adjacent individual images E each overlap with each other by up to 30%, up to 40%, up to 50%, up to 60%, or up to 90% of their width B. The overlap of adjacent individual images E facilitates the recognition of identical structures in the adjacent individual images E and thus the composing of an overall image

[0053] REVISED SHEET (RULE 91) ISA / EP of the coding K from the series S of individual images E. This composing or reading of the coding K can take place in the evaluation unit 22, but can also optionally take place outside the device 10. In the latter case, the device 10 would only generate the individual images E.

[0054] Furthermore, Fig. 3 can also be viewed as a representation of an overall image of the coding K composed from the individual images E (in particular by image processing, e.g. by means of an algorithm, in particular an artificial intelligence, Kl).

[0055] The aperture 14 used in the device 10 in the beam path 16 of the light source 13 can be fixed. Alternatively, the aperture 14 can be variable to allow changing the width B of the illumination area 15. This configuration makes the device 10 more easily adaptable to different container sizes and shapes.

[0056] Based on the described embodiments, the device and the method can be modified and adapted in many ways. For example, a matrix camera 19 with a size of at least 500 x 120 pixels can be used as the camera, for example with a size of 640 x 190 pixels. The recording frequency of the matrix camera 19 can be greater than 400 Hz, preferably greater than 800 Hz, even more preferably in the range of 1000 - 1200 Hz. The number of individual images E in a series S for covering the coding area 4 of a coding K can be, for example, 10 - 120, preferably 50 - 100. The light source 13 can be a continuous light source, i.e., it can emit light continuously while a series S of individual images E is being recorded. Alternatively, the light source 13 can be a stroboscopic light source.

[0057] Further modifications are certainly conceivable. All features described in connection with the method according to the invention can also be used individually or in any combination in the device according to the invention, and vice versa.

Claims

Claims Method for reading a code (K) arranged on a wall (2) of a vessel (1), wherein the code (K) occupies a code area (4) on the wall (2) of the vessel (1), characterized by the following steps: Creating an illumination area (15) on the wall (2) of the vessel (1) by means of a light source (13), wherein in a circumferential direction (U) of the vessel (1) a width (B) of the illumination area (15) is smaller than a width (b) of the coding surface (4), Generating a relative movement between the vessel (1) and the illumination area (15), Creating a series (S) of individual images (E) of the illumination area (15) by means of a matrix camera (19), wherein a relative movement takes place between the vessel (11) and the illumination area (15) between individual images (E) of the series (S), Composing an image of the coding (K) from the series of individual images (E). Method according to claim 1, characterized in that the coding (K) is preferably formed in a matrix-like manner as an arrangement of elevations (5) and / or depressions (5) in the wall (2) of the vessel (1). Method according to one of the preceding claims, characterized in that at least one individual image (E) of the series (S), preferably all individual images (E) of the series (S), overlaps with an adjacent individual image (E). Method according to one of the preceding claims, characterized in that the illumination region (15) is strip-shaped. Method according to one of the preceding claims, characterized in that the illumination region (15) has a width (B) of a maximum of 7 mm in the circumferential direction (U) of the vessel (1). Method according to one of the preceding claims, characterized in that the illumination region (15) in the circumferential direction (U) of the vessel (1) has a width (B) of 3 to 6 mm, preferably a width (B) of 4 to 5 mm. Method according to one of the preceding claims, characterized in that the relative movement between the vessel (1) and the illumination region (15) occurs continuously during the generation of the series (S) of individual images (E) or intermittently between each two individual images (E) of the series (S). Method according to one of the preceding claims, characterized in that the relative movement between the vessel (1) and the illumination region (15) is generated by a rotation of the vessel (1) about an axis (A).Device (10) for reading a code (K) arranged on a wall (2) of a vessel (1), comprising a light source (13) for generating an illumination region (15) on the vessel (1), and a camera (19) for recording individual images (E), characterized in that the camera (19) is a matrix camera (19), in that the light source (13) is configured to generate an illumination region (15) on the vessel (1) that has a maximum width (B) of 7 mm in a circumferential direction (U) of the vessel (1), and in that the device (10) has an evaluation unit (22) configured to compose an image of the code (K) from a series (S) of individual images (E). Device according to claim 9, characterized in that the light source (13) is configured to generate a strip-shaped illumination region (15) on the vessel (1).Device according to one of claims 9 or 10, characterized in that the light source (13) is configured to generate an illumination region (15) on the vessel (1) which has a width (B) of 3 to 6 mm, preferably a width (B) of 4 to 5 mm, in a circumferential direction (U) of the vessel (1). Device according to one of claims 9 to 11, characterized in that it has a drive (12) for generating a relative movement between the vessel (1) and the illumination region (15), preferably for generating a rotational movement of the vessel (1). Device according to one of claims 9 to 12, characterized in that it comprises a variable aperture (14) for varying the width (B) of the illumination area (15) in the circumferential direction (U) of the vessel (1). Device according to one of claims 9 to 13, characterized in that the light source (13) comprises a contrast-enhancing filter (17).

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