Device for recognising ridges and/or grooves on bottles, in particular in a labelling machine

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DESCRIPTION

Device to detect elevations and / or depressions in bottles, particularly in a labeling machine

The invention relates to a device for detecting elevations and / or depressions in bottles according to the preamble of claim 1 as well as a method for applying the device.

Elevations and / or depressions in bottle surfaces can occur, for example, in burrs and embossments on the bottle body, so-called engravings.

Bottles with burrs, such as for example beverage bottles, should preferably be labeled in such a way that the burrs are not covered by the label. Furthermore, the label must eventually be oriented towards an engraving. In order to detect the location of a burr or an engraving and to enable a subsequent rotation of the bottle to a desired position, a lamp reflection formed on the body of the bottle at different rotating locations of the bottle is examined in a known manner for irregularities. . In this respect, as a rule, only a part of the burr or etching can always be detected by the reflection of the lamp.

Document DE 10 2004 040 164 A1 describes an inspection device according to the preamble of claim 1. Such an inspection device comprises, for example, a semi-circular, uniformly illuminated lampshade which is arranged coaxially around the axis of symmetry of a bottle to be examined and having an aperture through which the surface of the bottle is examined with a camera for irregular reflections. On profiled bottle surfaces, the edges of the light reflections can, however, be irregularly shaped and difficult to detect precisely with low-contrast representation. It may also happen that the burr can be represented only in a small area at the edge of the light reflection. Therefore, with the known technique, the burr is not always reliably detected.

Document WO 2010/049137 A1 is state of the art according to article 54 (3) of the CPE and describes an inspection device with the characteristics of the preamble of claim 1 as well as with a light screen, on which they are configured different luminance areas.

The engravings are preferably arranged in the shoulder area of ​​the bottle. In the usual horizontal viewing direction of the camera, the engraving is then often outside the reflection of the lamp. Thus, irregular comparatively low contrast reflections occur in the engraving, the shape of which changes with the rotation of the bottle.

Due to these problems a control measurement with an additional fine alignment of the bottle is often necessary. This requires an additional inspection device and causes an undesirably large space requirement on the labeling machine.

Accordingly, it is an object of the invention to reliably detect burrs on as large an area of ​​the bottle wall as possible and to locate as reliably as possible engravings at different rotational positions of the bottle.

This is accomplished by patterning areas of different luminance on the light screen of the lighting unit. These superimpose the structures to be detected on the reflection and cause reflection areas of different luminosity, particularly with light lines on a dark background and dark lines on a light background. This makes it easy to detect burrs and engravings.

Also, the luminance transition between areas of different luminance is gradual. This favors the evaluation of camera images filtered with band-pass filters.

Preferably, the areas of different luminance are arranged in a fringe pattern. This provides a regular pattern in the reflection that reinforces the image contrast.

In one embodiment, the stripe pattern comprises two to four dark stripes. This improves rendering in essentially cylindrical bottle shapes, which reproduce vertical structures more sharply and more concentratedly than horizontal structures.

Preferably areas of different luminance alternate in the horizontal direction. This improves the detection of burrs that have a vertical path, which mainly cause disturbances in the reflection in the horizontal direction.

In a preferred embodiment, the areas of different luminance are configured as areas with different translucency. With this, dark screen areas can be made in a simple way.

Preferably, the luminous screen comprises a sheet, on or in which areas of different luminance are configured. This enables cost-effective and flexible realization of areas of different luminance, eg by foil printing, as well as easy switching between different lighting patterns.

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In a preferred embodiment, the Illumination unit further comprises a light source and the light screen, furthermore a diffuser glass, the sheet being arranged between the light source and the diffuser glass. In this way, unwanted pressure artifacts in the sheet can be smoothed out, such as, for example, overlapping grids and stripes.

Preferably, the light screen is in the form of a funnel open towards the bottle. In this way a flat spread reflection can be generated both in the cylindrical section of the bottle and in the shoulder of the bottle.

In a preferred embodiment, the camera is inclined towards the bottom of the bottle, its optical axis enclosing an angle of at most 80 ° with the main axis of the bottle. Therefore, not only large areas of the burr can be projected, but the lamp reflection also enables a particularly favorable representation of the shoulder area of ​​the bottle.

Preferably, the device further comprises a transport means for the bottle for traversing an image acquisition area of ​​the camera and a rotatable clamp arranged on the transport means for housing the bottle. Thus, a continuous stream of bottles can be inspected at different turning locations.

Another embodiment comprises a calculation unit for evaluating the detected reflection, for locating the elevations and / or depressions and determining an actual location of rotation of the bottle. With this, a theoretical turning location can then be reached.

The objective is also solved by means of a method for applying the device according to the invention in which the bottle is illuminated with the luminous screen, so that the light reflection overlaps the elevations and / or depressions to be detected at least temporarily and the reflection is photographed with a camera. The superposition of the structures to be detected with the areas of different luminosity of the luminous screen produces areas of reflection of different luminosity, particularly light lines on a dark background and dark lines on a light background. This makes it easy to detect burrs and engravings.

Preferably, the bottle in this regard moves through an image acquisition area of ​​the camera and in this regard rotates about its longitudinal axis, so that the reflection is reproduced at different rotation locations of the bottle. Thus, a continuous stream of bottles can be inspected at different turning locations.

In a preferred embodiment, a computing unit evaluates the images from the camera, detects the location of the elevations and / or depressions and determines from this an actual turning location of the bottle. By doing this, a theoretical turning location can then be reached.

Preferred embodiments are represented in the drawing and are explained below. They show:

Figure 1

Figure 2

Figure 3 is a schematic top view of a first embodiment, seen through the cut plane CC of Figure 2;

a schematic side view of the first embodiment, seen through section plane AA of Figure 1;

a schematic front view of the first embodiment, seen through sectional plane BB of Figure 1;

Figure 4

Figure 5

Figure 6 a schematic representation of a camera image with a light reflection to detect elevations or depressions in a bottle to be examined;

a schematic top view on a second embodiment, seen through section plane E-E of Figure 6; and a schematic side view of the second embodiment, seen through the cut plane D-D of Figure 5.

As can be seen in Figures 1 and 2, the inspection device 1 according to the invention comprises three cameras 3, respectively with an image area 3a indicated by dashed lines for the illustration of a bottle 7 passing next to the cameras 3 on a rotating transport means 5 (see arrow G). The cameras 3 are integrated into a lighting unit 9 with a funnel-shaped light screen 11, various lamps 13 and a protective disk 14. The bottle 7 is held by a rotary clamp 6, such as for example a motor-driven turntable with a centering device that can be lowered, upright and centered relative to the main axis 7a of the bottle 7. The holders 6 are indicated as batch way for additional bottles 7 for examination of a continuous bottle flow. The actuation of the clamps 6 is not represented and is symbolized by the arrow F.

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The light screen 11 comprises on its side facing the bottle 7 a diffuser glass 15, such as, for example, an opaque crystal glass or a translucent plastic plate, and on its side facing the lamps 13, a sheet 17 printed with different grades by sections with a 19 dye. The thickness of the dye layer 19 is represented in a very exaggerated way in the figures for a better understanding, corresponding to areas of great layer thickness, areas of lower luminance and vice versa. The translucency of the colorant 19 varies repeatedly in the horizontal direction along the light screen 11, so that dark areas 21a with low luminance and light areas 21b with high luminance in the horizontal direction alternate on the light screen 11. The transition of the luminance from the dark areas 21a to the light areas 21b and vice versa is gradual. Particularly from the parallel perspective of Figure 3 it is clear that the areas 21a, b of different luminance form on the light screen 11 an essentially vertically oriented fringe pattern 21.

As is further deduced from Figure 1, the lighting unit 9 comprises side mirrors 22, which are preferably configured as mirror sheets fixed on a transparent mirror body 22a. These reflect the light emitted 28 by the light screen 11 in the direction of the bottle 7.

According to Figure 2, the chambers 3 are inclined in the direction of the bottom of the bottle 7b, their optical axis 3b including an angle α of at most 80 ° with the main axis 7a of the bottle. The camera 3 looks in this connection through a camera opening 23 in the light screen 11 obliquely downwards, into the transition area of ​​the bottle shoulder 7c with the cylindrical section 7d of the bottle 7. With the camera 3 the image of the camera 25 represented schematically in Figure 4 with the reflection of light 27 is thus obtained. This is a mirror image of the luminous screen 11 distorted by the bottle 7. The light or dark stripes 27a, b of the light reflection 27 correspond in this respect essentially to the areas 21a, b of the fringe pattern 21.

Reflection 27 contains additional light or dark fringes 27a 'and 27b' corresponding to areas 21a, b reflected in mirrors 22. This part of reflection 27 reflected in mirrors 22 is schematically indicated in Figure 1 by the ray of light 28. The number of reflected fringes 27a 'and 27b' in the reflection 27 depends on the dimensioning of the lighting unit 9 and the distance between the light screen 11 and the bottle 7. If this distance were successively increased in the example, the side edges of the reflection 27 would migrate inward and first the outer stripes 27b 'would be hidden, then the neighboring stripes 27a' of the reflection 27.

A burr 7e and an engraving 7f are represented in the same way in Figure 4, which are configured in relief and / or as depression in the bottle 7. The images of the camera 25 taken at different rotation locations φ, for example, in Separations of respectively 30 ° are evaluated in a calculating unit (not shown) to locate the burr 7e and / or the engraving 7f and in this way determine an actual location of rotation φι of the bottle 7. As a rule, the surface of the bottle 7c, 7d unrolls completely before the cameras 3.

In the image from the camera 25, the contours of the burr 7e and the engraving 7f appear clearly defined, for example, as light lines on the dark bands 27a, a 'or as dark lines on the light bands 27b, b'. On the other hand, the transitions between the fringes 27a, a'b, b 'as well as the transitions between the areas 21a, b of the fringe pattern 21 are gradual. This assists in band-pass filtering in the evaluation of the image from the camera 25 for the distinction between the contours of the burr 7e or the engraving 7f and the fringes 27a, a'b ', b'. The fringes 27a, a ', b, b' of the reflection 27 are distorted with respect to the areas 21a, b of the light screen in perspective and appear compressed due to the essentially cylindrical shape of the bottle 7 in the horizontal direction.

The number of dark fringes 27a, a 'in reflection 27 is preferably three to eight. This makes it possible to detect the burrs 7c and the engravings 7d equally well. Depending on the number of dark areas 21a reflected in the mirrors 22 and which can be used in the reflection 27, the number of the areas 21a of the light screen 11 is preferably from one to eight, in case of a particularly favorable development of the invention , Two to four. However, the device is not limited to the above-mentioned number of dark stripes 27a, a 'or 21a respectively.

In order to detect the burr 7e as reliably as possible, the stripes 27a, a ', b, b' are aligned essentially parallel to the burr 7e. It is also possible, however, to align the stripes 27a, a ', b, b' obliquely with respect to the burr 7e, for example at an angle of up to 10 °. This improves the detection of the flash in the center of the camera image 25. In such a case, the areas 21a, b are to be arranged on the light screen 11 correspondingly obliquely, for example at angles of up to 10 ° to the vertical.

By an essentially vertically oriented fringe pattern 21 it is to be understood that fringe pattern 21 on a bottle 7 in an upright position generates a reflection 27 with fringes 27a, a'b, b 'oriented essentially parallel to the burr 7e or to the main axis 7a of the bottle 7. In an examination position different from this, the orientation of the stripe pattern 21 on the light screen 11 should be adjusted accordingly.

In general, it is possible to provide other light distributions on the light screen 11, for example essentially horizontally oriented fringe patterns or annular patterns in order to be able to detect particularly reliably elevations and / or depressions formed in a special way in the bottle 7.

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The cameras 3 are inclined so that not only large areas of the burr 7e can be observed in an image from the camera 25. Then, the reflection 27 is also particularly suitable for the detection of engravings 7f in the shoulder area 7c of the bottle. Depending on the shape of the bottle, the angle α can be, for example, 30 to 80 °, but if necessary also 80 to 90 °. The reflection 27 includes the etching 7f in the vertical direction preferably completely, so that it can be reliably detected at different rotation locations of the bottle 7.

For an easy adjustment of the inspection device 1 to different types of bottles and / or structures 7e, to detect, particularly for the height adjustment of the reflection 27, the lighting unit 9 is preferably configured in a height-adjustable manner.

The device 1 according to the invention can be equipped with several cameras 3, the image acquisition areas 3a of which overlap laterally, so that the bottle 7 passing next to the cameras 3 is reproduced with simultaneous rotation on the holder 6 in different rotating locations φ predetermined throughout its periphery. The number of the cameras 3 is not limited to the example shown. Preferably, the distance between the cameras 3 is as small as possible, in order to guarantee reproduction conditions as uniform as possible.

The luminous screen 11 is funnel-shaped and has a large surface as far as possible, in order to obtain a reflection 27 as large as possible that passes without interruption from the cylindrical part 7d of the bottle 7 to the shoulder of the bottle 7c. By this, the necessary number of images from the camera 25 for a reliable inspection of the bottle 7 can be minimized.

Both the light screen 11 and the sheet 17 are composed of several segments, preferably flat. This enables easy integration of the printed foils 17 into the light screen 11. However, the light screen 11 could also be configured in one piece and / or comprise curved surfaces, such as for example ellipsoidal segments.

The gradual transition of luminance from areas 21a to areas 21b and vice versa preferably corresponds to a wave-shaped pattern, eg a sinusoid.

The colorant 19 can be printed on either side of the sheet 17 or also on both sides of the sheet 17. It is also possible to incorporate the colorant into the sheet 17. It is also possible to apply the colorant 19 directly on the side facing the lamp 13 diffuser glass 15. However, the use of a sheet 17 has the advantage that it can be easily switched between different stripe patterns 21 to adapt the device to certain bottle shapes and / or structures on the bottle surface.

The colorant 19 suitably first has an optical absorption effect to shape the areas 21a with low luminance. However, it would also be possible to configure the areas 21b with high luminance with the aid of a fluorescent dye 19. Areas 21 a, b could also be configured by combining absorbent and / or fluorescent dyes 19.

The light sources 13 are, for example, LED background lamps. However, other types of lamps can also be used. The arrangement of the light sources 13 is not limited to the example of Figures 1 and 2. Similarly, only one light source 13 could be used in the lighting unit 9.

Alternatively, the dark and light areas 21a, b could be generated by illuminating the luminous screen with different area brightness. The light sources 13 could be configured for this purpose as an LED matrix, the LED elements of which are illuminated with different brightness. Depending on the number and size of the elements, they should be arranged at a suitable distance from the diffuser glass 15 so that a smoothed light pattern 21 is formed with gradual brightness transitions. With this variant, it is also possible to generate 21 different patterns without modifications.

The lighting unit 9 preferably comprises accentuated reflective or backscattering inner walls 9a, such as are known, for example, from Ulbricht spheres to increase the light output and / or to ensure uniform illumination of the light screen 11.

This improves the quality of camera images with short exposure times. The lighting unit can be provided for this purpose also with additional mirrors and / or backscattering partition walls (not shown). The disk 14 provides protection against contamination of the lighting unit 9, but it is not absolutely necessary.

The transparent mirror body 22a results in that, particularly in interaction with the reflective or backscattering inner walls 9a, the luminous screen 11 is also illuminated in the transition area towards the mirrors 22 from different directions and, therefore, with brightness as uniform as possible. By this, clearly demarcated dark lines are avoided at the transition from the light screen 11 to the mirror 22 or in the corresponding areas of the reflection 27.

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The transport means 5 is preferably a transport carousel, as indicated in Figures 1 and 2. But it could also be linear or curved. The directions of rotation F and G of the holder 6 and of the transport means 5 are preferably identical, but could also be opposite.

A second embodiment is described below, which differs from the first embodiment essentially by an alternative funnel shape of the light screen 11, as well as by the fact that side mirrors 22 are not provided. The remaining characteristics correspond, where not indicated otherwise, with those of the first embodiment and, therefore, they are not described again or are not provided in part in Figures 5 and 6 with references.

As can be seen in Figure 5, the light screen 11 of the second embodiment is also funnel-shaped in top view. It can be formed, for example, by five flat segments 11a-e, which are respectively directed towards an examination position of the bottle 7 within the image acquisition area 3a. The areas 21a, b are configured in the second embodiment not only in the middle segments 11b, d, e, but also in the lateral segments 11a, c. Therefore, with the irradiation of the bottle 7 the reflection 27 represented in Figure 4 is also produced, however, the fringes 27a ', b' of the first embodiment generated by reflection in the mirrors 22 in the second embodiment by other fringes 27a, b generated by direct irradiation of bottle 7. Correspondingly, the preferred number of dark areas 21a of light screen 11 in the second embodiment is from three to eight.

The dark and light areas 21a, b may be inclined according to the shape of the light screen 11 by various degrees from the vertical, so that essentially vertically oriented fringes 27a, b occur in the reflection 27. In the front view, the stripes 21a and / or 21b preferably include an angle of at most 45 ° with the vertical or the main axis 7a of the bottle 7 in the parallel perspective. Suitable fringe patterns 21 can be calculated, for example, by ray tracking for a predetermined funnel shape, so that a predetermined reflection 27 is produced in the simulation on the type of bottle to be examined.

The features of the described embodiments can be combined. Particularly the shaping of the light screen 11 is not limited to the examples shown. As an example, the screens can be tilted orthogonally, so that their top view becomes a side view and vice versa. Likewise, the areas 21a, b can be configured on curved sections (not shown) of the light screen 11.

With the inspection device according to the invention it is possible to work as follows:

A bottle 7 fixed in the holder 6 is translated with simultaneous rotation around its longitudinal axis 7a along the transport section 5 to the capture area 3a of a chamber 3. While the bottle 7 is within the image area 3a of the camera 3 takes the shots 25 of the reflection 27 at predetermined locations of rotation φ of the bottle 7 or at predetermined time intervals and is subsequently processed with an evaluation of the image in the computing unit 29. If the bottle 7 leaves the image area 3a of the chamber 3 before the entire circumference of the bottle 7 has been examined (depending on the speed of transport and rotation of the transport means 5 or of the clamp 6), to the image area 3a is joined at least one additional image area 3a from another camera 3 overlapping, until the entire circumference of the bottle is registered by the camera shots 25. By evaluating the taps 25 in the computing unit, the location of a burr 7e and / or an engraving 7f is detected and an actual turning location φι of the bottle 7 or of the clamp 6 is determined, so that it can then reach a desired turning location φ = of bottle 7.