Abstract:
A method for testing a monitoring device ( 20 ) of an automatic labeling machine ( 10 ) for containers ( 12 ) for correct functioning, in the case of which, a specially marked measuring container ( 14 ) is fed thereto, upon whose detection, a labeling process is discontinued at least for this measuring container ( 14 ), and the measuring container ( 14 ) provided with markings ( 16 ) is scanned by at least one optical sensing device ( 21 ) of the monitoring device ( 20 ).

Description:
[0001]    This claims the benefits of German Patent Application DE 10 2008 054 238.5, filed Oct. 31, 2008 and hereby incorporated by reference herein. 
         [0002]    The present invention relates to a method for testing a monitoring device of an automatic labeling machine for correct functioning. 
       BACKGROUND 
       [0003]    Labels are typically applied to beverage containers and bottles filled with beverages in a continuous process by automatic labeling machines which constitute part of a rotary machine used for bottling. Poorly or slantingly applied labels can signify a deficiency which, under unfavorable conditions, can lead to shut-down of the bottling machine. To be able to continuously check for correct placement and fixation of the labels, a camera, or optionally a plurality of cameras having subsequent image analysis can be configured downstream of the labeling machine. 
         [0004]    A labeling machine of this kind can be inferred from the German Examined Specification DE 199 11 074 B4. In the case of this known device, the analyzed images from a camera configured downstream of the labeling station are not only used for monitoring for correct placement of the labels, rather, correction signals are also generated therefrom for controlling a correction device for the particular labeling station or for synchronizing a gripper cylinder and removal elements. Thus, to a certain degree, this known system allows for correction of the label placement during continuous operation of the machine. 
         [0005]    However, the known monitoring devices are only able to function with the desired degree of reliability when they, themselves, are not out of alignment. To correctly position the camera that is customarily used and to calibrate, respectively initialize this position, test containers can be used, for example, which have a suitable test pattern that can be recognized by the camera and used by the downstream evaluation unit to check the camera settings. 
         [0006]    Such a test container and a test arrangement for a control device for containers is discussed in the German Patent Application DE 10 2006 022 492 A1. The test container has a plurality of uniform horizontal marking rings on the container surface that are intersected by vertical markings, thereby forming a grid-type marking structure. With the aid of this marking structure, and by using a system for precise height adjustment of the test container, the camera can be calibrated and adjusted. 
         [0007]    Problems can always arise during operation of a labeling machine when an undetected camera misalignment either results in a failure to detect improperly applied labels or in an insufficient or even faulty correction of the setting data used for applying the labels. Often the necessity for a repeated adjustment and subsequent recalibration of the camera can only be deduced by taking precise measurements of containers provided with labels. In this case, however, a multiplicity of containers having improperly glued-on labels may have already been considered to be acceptable and fed for further processing and/or packaging. 
       SUMMARY OF THE INVENTION 
       [0008]    An object of the present invention is to devise a method which will make it possible to assess and test the sensing quality and/or precision of a monitoring device for an automatic labeling machine. 
         [0009]    The present invention provides a method for testing a monitoring device of an automatic labeling machine for containers for correct functioning, 
         [0000]    wherein a specially marked measuring container is fed thereto to the labeling machine, and, upon its detection, a labeling process is discontinued at least for this measuring container, and the measuring container provided with markings is scanned by at least one optical sensing device of the monitoring device. 
         [0010]    To label containers, one frequently used design variant of a labeling device provides for them to be transferred via a spacing worm, evenly spaced apart from one another, to an infeed starwheel of the labeling machine. From this infeed starwheel, each individual container is slid onto a separate centering plate located on a rotating container table. This infeed starwheel is connected to the container table by way of a gear. The container table, which is set into rotation by a main gear, advances the containers through a processing section, for example, for labeling, brush-on, and label control processes, etc. It is self-evident that the method according to the present invention may also be used for other variants of conveying and/or labeling devices. 
         [0011]    To achieve precise labeling, the container must normally be fixed in position and centered when passing through the processing section. To that end, each container is tightly clamped between the centering plate and a centering bell that is lowered from the top machine portion. To be able to ascertain an exact position of the containers, it may be useful to monitor the conveying units and devices, such as sensors, monitoring devices, labeling units and many others as well, via a machine position transducer or the like. Such a machine position transducer is coupled to the labeling machine in a way that allows it to provide each container with a label with the desired precision. In addition, such a position transducer may be used to determine the instantaneous position of each individual rotary table and thus of each individual container at any time. 
         [0012]    A use of computer-controlled servomotors induces a defined rotation of the centering plate that may be required for the labeling and brush-on processes. These servomotors may drive the individual centering plates separately and thus render possible a precise adaptation of the labels. 
         [0013]    If the exact positioning of the labels placed on the containers is to be checked along the further travel path of the containers, cameras coupled to an image analysis may be used at an appropriate location. For example, a location in the vicinity of a discharge starwheel of a rotary machine may be suited as a camera position. In the present context, a camera of this type is used for label control processes and thus to control for proper functioning of the labeling units and the cooperation thereof with the conveying devices. The label control that is integrated at the discharge starwheel and is used as a monitoring device makes it possible to detect incorrectly labeled or unlabeled containers that have been discharged for further processing. Once detected, these faulty containers can be separated out in response to a signal to this effect and be diverted, for example, via a discharge conveyor belt. Thus, the camera acts as an optical sensing device of the monitoring device for scanning the containers. The signals generated by an image analysis circuit downstream of the camera are transmitted to the discharge starwheel in a way that either permits a specific container to be transferred out or routed further to subsequent devices of the labeling machine. For this purpose, the present invention additionally includes a program for detecting and processing specially marked measuring containers that may be introduced into the labeling machine during operation, in order to be able to selectively scan these measuring containers using the sensing device, respectively the camera and, on the basis of the acquired imaging signal, to be able to check and assess the alignment thereof. The measuring container does not produce any errors during the labeling process. Rather, the labeling is discontinued or interrupted in response to the measuring container passing by, to allow scanning of the surface and/or structure thereof without any disturbing influences. Thus, a method is provided for testing the monitoring device of the automatic labeling machine for correct functioning. 
         [0014]    It is important that the functions of the monitoring device be regularly checked in the manner described to be able to detect and rectify possible misalignments of the monitoring device as quickly as possible. 
         [0015]    The optical sensing device may be constituted of at least one camera having downstream image analysis. However, a plurality of such cameras may also be provided at various machine positions. The at least one optical sensing device, respectively camera scans each container and, with the aid of the downstream image analysis, ascertains all possible errors of the imaging. By scanning and sensing the measuring container, correct image coordinates are then able to be assigned with the aid of the previously set container coordinates, making it possible to identify skewed or too high or too low placement of the markings of the measuring container in the imaging of the camera. To be able to regularly execute the test program in the labeling machine, one or even a plurality of specially marked measuring containers should be introduced into the running machine. These measuring containers are provided with defined, optically uniquely identifiable and assignable features to permit accurate recognition of a faulty imaging of the optical sensing device, respectively camera. 
         [0016]    The measuring container preferably has a suitable identifying marking that is used for interacting with a sensor of the labeling machine, so that an introduced measuring container may be uniquely recognized as such. These features on the measuring containers could be constituted of an optical, magnetic, inductive and/or combination identifying marking; an RFID identifying marking is also conceivable. These identifying markings permit interaction with a corresponding sensor that may be mounted on the infeed starwheel of the labeling machine, for example, so that, in connection with the signal from the machine position transducer, the instantaneous position of the measuring container may be tracked and corresponding machine commands initiated at any time. 
         [0017]    The optical markings of the measuring container are used exclusively for interacting with the optical sensing device, respectively the camera. Thus, the markings may be scaled, for example, through the use of a multiplicity of horizontal rings and vertical lines. This may be achieved, for example, by using black lines and/or engravings. The marking lines completely encircle the measuring container and are optionally spaced at the same or different intervals. These intervals are preferably adapted to the image analysis circuit of the monitoring device to enable the acquired measuring container images to be uniquely assigned to specific camera misalignments. Another possible embodiment of the measuring containers could provide for using a different color design to differentiate them from the other containers. Other variants would include introducing patterns, such as a black grid pattern or a colored checkered pattern. 
         [0018]    Thus, it is highly important to detect the measuring container and determine its position since, at least for this measuring container, it is intended that the labeling process be interrupted at the labeling station and that the monitoring device check each recognized measuring container using its image coordinates. In addition, with the aid of the previously determined position, it should thereby be possible for the measuring container to be transferred out at a specified location once it has passed through. During its passage through the labeling machine, the position of the measuring container may be determined by at least one sensor at the infeed starwheel of the labeling machine. In addition, the position is determined by coordinating the centering plate with the position transducer of the machine, it being possible to additionally control other devices correspondingly. 
         [0019]    Also, an additional sensor at a position downstream of the outward transfer [point] may monitor the passing-by of the measuring container. If the measuring container is detected as a result of the monitoring, an error signal may be subsequently generated which may lead, for example, to shut-down of the machine or to a repeated outward transfer process at another outward transfer position. If no further outward transfer position is provided, upon detection of the measuring container by the additional sensor, a stop signal for the labeling machine and/or for conveying devices configured upstream and/or downstream of the same may preferably be triggered. 
         [0020]    It is worth mentioning that the feeding, detection and outward transfer of the measuring container take place during ongoing, uninterrupted operation of the labeling machine. The label feeding and affixing are separately controllable for each individual container. Upon detection of the measuring container as it passes by, the control of the label feeding and affixing is temporarily deactivated; the control is then reactivated for a subsequent container. This deactivation and activation of the label feeding and affixing processes may be carried out on the basis of the detected position of the measuring container that is also tracked during its passage through the labeling machine. 
         [0021]    In accordance with another possible design variant of the method according to the present invention, the alignment and/or focusing of the at least one optical sensing device, respectively camera on the basis of the acquired measuring container images may be corrected during continuous operation of the labeling machine. Thus, depending on the adjustability of the camera, this may obviate the necessity of shutting down the entire machine, in the case that a faulty camera position and/or alignment are detected. 
         [0022]    To record and/or check the function and setting of the at least one optical sensing device, the measuring container may be fed to the labeling machine as a function of time or as a function of the number of containers. This means that the measuring container may be repeatedly fed in, for example, following a defined processing time or following a specified number of containers that have already passed through the machine. 
         [0023]    Other features, objectives and advantages of the present invention are derived from the following detailed description of a preferred specific embodiment of the present invention that is not to be considered as a limiting example and that makes reference to the enclosed drawing. In this context, the same components are basically denoted by the same reference numerals and, in part, are not explained multiple times. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0024]      FIG. 1 : shows a schematic configuration of a design variant of a labeling machine; 
           [0025]      FIG. 2 : shows a simplified specific embodiment of a container table of a rotary machine for labeling containers; 
           [0026]      FIG. 3 : shows one possible specific embodiment of a marked measuring container having optically identifiable markings. 
       
    
    
     DETAILED DESCRIPTION 
       [0027]    The schematic representation of  FIG. 1  shows a typical configuration of a labeling machine  10  having an infeed starwheel  32  and a discharge starwheel  36 , as well as a container table  34 . Rotating spacing worm  30  spaces apart containers of container stream  12  arriving on a conveyor belt (not shown) in transport direction  50 , by the requisite distance, without gaps, to ensure an error-free transfer into a recess in infeed starwheel  32  that is adapted to the container shapes. 
         [0028]    Infeed starwheel  32  transfers containers  12  to centering plates  64  which are mounted on container table  34  (compare  FIG. 2 ). Container table  34  is set into rotation in clockwise direction  54 . Containers  12  standing on centering plates  64  are moved past at least one labeling unit  28  and labeled. Marked measuring containers  14  likewise standing on centering plates  64  are recognized as such (as explained in greater detail in the following) and are not labeled at labeling unit  28 . Using an optical sensing device- 21  in the form of a camera  22 , monitoring device  20  that follows ascertains the correct fixation or also, however, the possible absence of labels, and transmits the information to a downstream image analysis  24 . 
         [0029]    In the sensing of measuring container  14 , this image analysis  24  has the task of comparing the current marking image of measuring container  14  to a stored reference image, using a reference measurement as a basis. On the basis of this comparison, the entire state of monitoring device  20  may be ascertained, and any discrepancies, such as a possible misalignment of camera  22 , may at least be recognized. Depending on the machinery, such a detected camera misalignment may be compensated, when indicated, by an automatic realignment, for example. Alternatively, camera  22  may be manually aligned. To accomplish this, one of containers  12  may be replaced with a specially marked measuring container  14  that passes through machine  12  in the following manner. Relevant to the alignment of camera  22  is, first and foremost, the passage of such a marked measuring container  14 . 
         [0030]    Mounted just before the transfer of container  12  onto infeed starwheel  32  is a sensor  26  whose purpose is to detect a marked measuring container  14  which is to pass through machine  10  instead of a normal container  12 . With the aid of sensor  26 , the position and transfer of measuring container  14  may be precisely determined during its passage through machine  10 . Sensor  26  is operatively connected to the at least one downstream labeling unit  28  and to monitoring device  20 . In addition, a machine position transducer (compare  FIG. 2 ) communicates the position of the containers to these devices. 
         [0031]    The position coordinates of measuring container  14  are transmitted to labeling unit  28  in order to prevent measuring container  14  from being labeled in this case. Monitoring device  20  is able to recognize this measuring container  14 , on the one hand, due to the absence of the label and, on the other hand, by scanning the contour of the bottle, respectively surface markings  16  thereof. 
         [0032]    Containers  12  are individually transferred to discharge starwheel  36  during operation and are conveyed further in transport direction  50 . Once detected, measuring container  14  is, in fact, also transferred to discharge starwheel  36 , but is subsequently diverted onto a discharge conveyor belt  40 . This discharge conveyor belt  40  may be situated at discharge starwheel  36  at a specified location or at a conveying device downstream therefrom. 
         [0033]    Normally, only nonconforming containers  12  are loaded onto this discharge conveyor belt  40 . In the present context, discharge conveyor belt  40  may be used to divert marked measuring containers  14  away from the further conveying process. Containers  12 , respectively measuring containers  14 , which have been separated out, are transported along a discharge path  52  and accumulated at a collection point (not shown), or they are deposited in a receptacle that has been set up. 
         [0034]      FIG. 2  shows a simplified specific embodiment of a container table  34  of a rotary machine. Mounted on container table  34  are centering plates  64  on which containers  12 , as well as marked measuring containers  14  (compare  FIG. 3 ) may be carried further to individual processing stations, such as a labeling unit, labeling control, etc. (not shown). Containers  12 ,  14 , which are transferred from infeed starwheel  32  to container table  34 , are fixed in position and tightly clamped by a centering bell  62  and centering plate  64 . Centering bell  62  is lowered from machine top portion  60  and grips containers  12 ,  14  around the bottlenecks thereof. 
         [0035]    By way of a main gear  68 , a machine position transducer  66  is in toothing engagement with container table  34 . This main gear  68  is driven by a main drive gear  70  which, in turn, is driven by a main drive motor  74  via a gear unit  72 . With the aid of machine position transducer  66 , the position of each container  12 ,  14  on machine  10  is determined by a suitable monitoring circuit and, if indicated, made available as position signals to other control circuits. 
         [0036]    One possible specific embodiment of a marked measuring container  14  is shown in  FIG. 3 . This specific embodiment shows one possible placement of markings  16 . For example, horizontal marking rings and vertical marking lines may be introduced into an outer envelope surface of marked measuring container  14 . These markings  16  may be optionally applied at regularly or irregularly spaced intervals. 
         [0037]    Moreover, measuring container  14  has a uniquely identifiable marking  18  for interacting at least with sensor  26  (compare  FIG. 1 ). This marking  18  may advantageously be formed by an RFID identifying marking or the like. Optical, magnetic, inductive and/or combination identifying markings  18  are possible, which, in each case, interact with the suitably configured, corresponding sensor  26  of labeling machine  10 . In this manner, a measuring container  14  that is introduced into machine  10  may be uniquely identified as such, and its position may be tracked with the additional aid of machine position transducer  66  (compare  FIG. 2 ). Labeling unit  28  is briefly deactivated as soon as measuring container  14  passes by to ensure that measuring container  14  does not receive a label and that its outer contour and markings  16  are able to be subsequently captured by camera  22 . 
         [0038]    The present invention is not limited to the preceding exemplary embodiments. Rather, a multiplicity of variants and modifications are conceivable that make use of the inventive idea and, therefore, likewise fall within the scope of protection.