Recognition device for recognizing empty trays in a conveying device

Abstract

The present invention relates to a recognition device (10) for recognizing empty trays (LW) in a conveying device (100) for trays (W) for transporting objects (O), comprising: an inspection light source (20) for generating inspection light beams (PL) with an inspection light spectrum (PS), said inspection light source having an inspection polarization filter (22) with a first polarization angle (PW1) and a guide device (24) for guiding the inspection light beams (PL) through the inspection polarization filter (22) into an inspection region (PB); a sensing device (30) for sensing reflection light beams (RL) reflected from the inspection region (PB), said sensing device having a reflection polarization filter (32) with a second polarization angle (PW2), which is different from the first polarization angle (PW1); a determination device (40) for determining objects (O) in the inspection region (PB) on the basis of polarized reflection light beams (RL) which passed through the reflection polarization filter (32).

Description

[0001] Detection device for detecting empty trays in a conveyor device

[0002] The present invention relates to a detection device for detecting empty tubs in a conveyor device, a conveyor device with such a detection device and a detection method for implementation on such a detection device.

[0003] It is known that conveyor systems are used to convey trays for transporting objects. An example application for this is hand luggage scanners at airport security gates. There, objects in the form of hand luggage, jackets, items of clothing, shoes, or similar are placed in trays to be transported through scanner devices using the conveyor system. Since the trays must be conveyed back to the beginning of the conveyor system after being emptied, i.e., after the objects have been removed by the passenger, a return conveyor option is usually provided. This is often integrated into such a scanner system and leads, for example, from the end of the conveyor belt back to the beginning of the conveyor belt.Since space within the housing of such a scanner device is typically very limited, such return channels are very narrow, and it is crucial that only completely empty trays are introduced into this return channel. Otherwise, there is a risk of jamming or blockage of incompletely emptied trays in such a return channel.

[0004] With known devices, this sometimes means that a manual check must be carried out to ensure that only empty trays are actually fed into the return conveyor. While it is currently possible to detect objects in trays using image recognition techniques, this primarily relates to identifying specific objects as such. In particular, it is not possible to detect missing objects. Particularly when some objects are very small, for example a boarding pass in the example described of a hand luggage scanner, these are often not recognizable as objects by image recognition techniques or only with great effort. Object recognition using imaging techniques is also very expensive because of the high computing power required to evaluate the image information accordingly.However, as already explained, not all objects are actually recognizable as such, so that the detection of the absence of any objects cannot be carried out with absolute certainty.

[0005] The object of the present invention is to at least partially remedy the disadvantages described above. In particular, the object of the present invention is to detect empty trays for a conveyor device with a high degree of probability in a cost-effective and simple manner.

[0006] The above object is achieved by a detection device having the features of claim 1, a conveying device having the features of claim 13, and a detection method having the features of claim 14. Further features and details of the invention emerge from the subclaims, the description, and the drawings. Features and details described in connection with the detection device according to the invention naturally also apply in connection with the conveying device according to the invention and the detection method according to the invention, and vice versa, so that with regard to the disclosure of the individual aspects of the invention, reference is always made to each other.

[0007] According to the invention, a detection device is used for detecting empty trays in a conveyor device for trays used to transport objects. Such a detection device has a test light source for generating test light beams with a test light spectrum. This test light source is equipped with a test polarization filter with a first polarization angle. Furthermore, the test light source has a guide device for guiding the test light beams through the test polarization filter into a test area. The detection device is further equipped with a detection device for detecting reflection light beams reflected from the test area using a reflection polarization filter with a second polarization angle that differs from the first polarization angle.Furthermore, a determination device is provided for determining objects in the test area on the basis of polarized reflection light rays passing through the reflection polarization filter.

[0008] The guide device can, for example, comprise reflector elements to achieve a vertical concentration of the test light beams through the test polarization filter into the test area. This can result in improved utilization of the light output. Other optical control elements, such as lens elements and / or aperture elements, can also be provided as part of the guide device.

[0009] According to the invention, the detection device serves to detect the absence of objects in trays in a conveyor device. For this purpose, a check area is defined, which can, for example, represent part of the conveyor device. For example, such a detection device can represent a check area at the end of a conveyor device of a previously discussed hand luggage scanner. Before a reclaim through a narrow return channel takes place, the detection device can detect empty trays with a high degree of certainty, preferably automatically.

[0010] In order to ensure the absence of objects within the scope of the present invention, in contrast to the specific detection of objects within a tub, with a high degree of certainty, a defined light beam path is provided, which is explained in more detail below.

[0011] When a tray reaches a test section of the conveyor device, a plurality of test light beams is generated with the help of the test light source. The test light beams spread around the test light source and have a defined test light spectrum. In order to direct the test light beams into the test area, at least one guide device is provided, which can, for example, have reflection sections of the reflector elements already explained above. This serves in particular to provide a defined beam path in order to emit the test light beams from the test light source towards the test area. On the way from the test light source to the test area, all test light beams also pass through the test polarization filter. This ensures that only polarized test light beams reach the test area.In other words, the test area is now irradiated with a test light in the form of the test light rays, which on the one hand has a defined test light spectrum and on the other hand has a defined polarization according to the first polarization angle of the test polarization filter.

[0012] The test light source is preferably designed as a planar light and can have a plurality of planarly arranged light sources. For example, LED light sources, in particular infrared light sources, are provided, which generate the test light as infrared test light. This creates a planar light concentrated on the tank with uniform illumination and, compared to a point lamp, reduces or even eliminates the risk of disruptive reflections. The planar design also ensures a planar distribution of the electrical power, so that heat generation during operation of the test light source is also distributed evenly. Localized overheating can be avoided in this way.

[0013] As soon as the appropriately polarized test light reaches the tray, two different situations must be distinguished. If the tray is an empty tray, all of the test light strikes the empty bottom section of the tray in the test section. This results in a defined and precise reflection at this bottom section, which in particular does not change the polarization of the test light or changes it only to a very small extent. The reflection creates reflected light rays, which leave the test area again and can be picked up by a detection device of the recognition device. However, to reach the detection device, the reflected light rays must still overcome the reflected polarization filter. The reflected polarization filter has a second polarization angle that differs from the first polarization angle of the test polarization filter.This means that when the test light rays are precisely polarized by the corresponding reflection, exclusively at the bottom of the empty tub, they retain their polarization according to the first polarization angle. This also means that these reflected light rays, with their constant polarization, cannot penetrate the reflected polarization filter, or can only do so to a very limited extent, because the second polarization angle, which is different from the first polarization angle, prevents this. It is clearly visible here that, in an empty tub, the test light is reflected back to the detection device as reflected light in such a way that it cannot be detected by the device, or can only be detected to a very limited extent, because the reflected polarization filter prevents it from entering the detection device.In this case, the image perceived by the detection device appears dark or completely blackened, so that it can be assumed that the tub is empty.

[0014] If, contrary to the above explanation, an object is transported in the tank, inspection light rays reach this object in the same way as soon as it is in the inspection area. The inspection light rays are now reflected at this object in a different way than is the case at the bottom of the tank. In particular, this preferably diffuse reflection changes the polarization of the incoming inspection light rays, so that the resulting reflection light rays have a different polarization than the inspection light rays. Because such reflection light rays reflected from the object now have a different polarization compared to the inspection light rays, they can at least partially pass through the reflection polarization filter and thus be detected by the detection device.The image perceived by the detection device therefore only shows those reflected light rays that have undergone a change in polarization due to reflection from objects. This results in the image captured by the detection device only showing lines and contours in those areas that, due to the changed polarization, belong to an object, in particular an object edge or an object contour. This allows the contours of the objects to be recognized, so that only for such objects can reflected light rays penetrate the reflected polarization filter and be perceived by the detection device.

[0015] Based on the above explanation of the empty tray and the tray containing an object, it is clearly visible how the detection device can now use these two different detection situations in a very simple and, above all, computationally efficient manner to determine the absence of any objects in the test area. It can therefore be assumed that an object can only be present in the tray if reflected light rays were able to penetrate the reflection polarization filter. In contrast, a completely dark image is to be interpreted by the detection device as meaning that no object was detected in the test area, since no diffuse reflection with different reflection angles within the test area led to a change in the polarization of the test light rays.The actual shape or type of the objects and the corresponding shape of the contours are not important in this evaluation, so that the absence of objects can be detected with a high degree of certainty and with very little computational effort.

[0016] Based on the above explanation, it is clear that image analysis to search for objects is no longer necessary in a very cost-effective and simple manner, but rather the detection result—the absence of objects—in the case of a black or essentially black image can be output directly by the detection device. Complex and computationally intensive image analyses are no longer necessary. In addition to reducing computing costs and the associated computing time, this also leads to the advantage of a significant cost reduction. The use of test light sources and correspondingly simple detection devices means that the structural hardware that supplies the data for the detection device can be small and inexpensive, but above all, also very robust.Furthermore, pure contour detection and the polarization correlation between the inspection light source and the detection device enable a high tolerance for a wide variety of object types and / or object positions. In other words, every object within the tank is non-specifically detected with very high robustness and a high degree of reliability. Conversely, the absence of any non-specific objects, even very small ones, can also be detected.

[0017] It can be advantageous if, in a detection device according to the invention, the first polarization angle and the second polarization angle are aligned at 90° or substantially 90° to each other. This substantially complementary alignment of the two different polarization angles further enhances the effect already explained. In particular, it ensures the most complete filtering possible of non-diffusely reflected test light beams, so that the distinction between contours by diffusely reflected reflection beams and non-diffusely reflected reflection beams is enhanced. This leads to improved discrimination and thus to further improved detection of missing objects in the respective tray in the test area.

[0018] It is further advantageous if, in a detection device according to the invention, the test light source generates the test light rays in a test light spectrum in the range invisible to the human eye, in particular in the infrared range. The wavelength here is, for example, approximately 804nm and is therefore relatively small in the spectrum of ambient light. This reduces or prevents the influence of ambient light on the detection device. By means of sufficiently strong illumination at this wavelength (for example, approximately 804nm) and the resulting distance from the light component of this wavelength which is small in the ambient light, interference and the influence of the ambient light are greatly reduced and reliable empty detection can thus be achieved up to 20,000 lux ambient light. The test light used is, for example, approximately804nm is still at the beginning of the infrared range (still the visible part) and is therefore very cost-effective using inexpensive IR LEDs compared to pure infrared LEDs. This means that the lighting can be implemented very cost-effectively. Illumination in the completely visible wavelength range would be very bright and disruptive in passenger areas. The use of an infrared range therefore means that a very cost-effective test light source in the form of IR LEDs in the visible wavelength range can be used. In addition, the test light spectrum differs largely from the ambient light, especially when the light inside a building is purely artificial. This also means that, in addition to the correlation of the different polarizations, the test light spectrum can now also be better distinguished from the otherwise existing ambient light from a spectral point of view.The test light spectrum is preferably arranged very close to, but not or only partially within, the range visible to the human eye. This leads to a further reduction in costs, since correspondingly cost-effective test light sources and detection devices can be used. In order to further enhance the functionality according to the invention, the test light spectrum is equipped with a very narrow width, i.e., has a narrow design. A possible width for the test light spectrum is, for example, approximately 10 nanometers. This leads to a further significant reduction in the disruptive influence of ambient light. Further advantages can be achieved if, in a detection device according to the invention, the test light source has a plurality of individual test illuminants, which in particular have rectified or essentially rectified radiation directions.Of course, a single, powerful test light source is also conceivable. However, the use of multiple test light sources, which in particular have rectified, preferably parallel or essentially parallel radiation directions, can bring advantages. Parallel radiation from multiple test light sources, for example, allows a particularly uniform distribution of the test light beams over a large test area. The irradiation and thus the emission from the test light sources along the radiation directions preferably occurs from above onto the test area, as will be explained in more detail later with reference to the conveyor device. In particular, the test light source is designed as a surface light source for this purpose, as already described above.

[0019] It is also advantageous if, in a detection device according to the invention, the test light source generates the test light beams with a brightness above the brightness of the ambient light. In other words, the test light beams from the test light source outshine the ambient light in order to further reduce its influence on the detection device. This can be specified automatically, done manually by entering light parameters for the ambient light, or carried out in a controlled manner using an ambient light sensor. It can also be advantageous if the wavelength of the ambient light is known and accordingly not only the intensity but, as already explained, also the spectrum width can be differentiated from this defined ambient light.

[0020] Further advantages can be achieved if, in a detection device according to the invention, a reflection spectral filter is arranged in the beam path upstream of the detection device, with a transmission spectrum that corresponds or substantially corresponds to the test light spectrum. Such a reflection spectral filter thus prevents wavelength ranges that are not in the transmission spectrum and thus also not in the test light spectrum from reaching the detection device. This increases the reliability of the detection according to the invention, since ambient light with different polarization directions can partially penetrate the reflection polarization filter, but can no longer penetrate the reflection spectral filter due to the transmission spectrum additionally connected downstream.In other words, this makes it possible, on the one hand, to filter out diffusely polarized ambient light based on the spectrum and, on the other hand, to use the polarization differences for the detection functionality as described. Other light influences or glare from the ambient light can be reduced or even largely eliminated in this way.

[0021] It is also advantageous if a detection device according to the invention has a testing area for temporarily receiving trays of the conveyor device, in particular if the testing area forms a section of the conveyor device. If the conveyor device has, for example, a conveyor belt or conveyor rollers, these are also arranged in the testing area and serve to transport the trays into the testing area and, if detected as empty, out of it again. This is particularly integrated into the hand luggage scanner already discussed several times.

[0022] It may also be advantageous if, in a detection device according to the invention, a testing distance is formed between the testing light source and the detection device on one side and the testing area on the other side. This testing distance is particularly designed as a fixed testing distance and is larger than the distance typically found in such trays for hand luggage. It is also preferably large enough to allow a human body part to enter the tray, in particular to enable the removal of an object from an object tray.

[0023] It is also advantageous if, in a detection device according to the invention, the inspection area has a position sensor for detecting a tub conveyed into the inspection area by the conveyor device. This allows the detection method explained later to be carried out not only when the tub is stationary, but also at least partially while the tub is moving. Strip-by-strip detection and / or complete detection of the entire tub can occur. By applying it to moving tubs, the detection device can be arranged even more flexibly at security gates, in particular at any location along a conveyor device and not necessarily at the end of the conveyor device. The throughput of inspected tubs is also accelerated, since there is no time loss due to the detection of stationary tubs.With the help of the position sensor, for example in the form of a light barrier, a mechanical switch, a magnetic switch, or even an optical detection device, it is possible to synchronize the detection process with the movement of the tub on the conveyor. In the simplest case, the detection process starts with a position signal from the position sensor when a tub has been moved to the desired position.

[0024] Further advantages are achieved if, in a detection device according to the invention, the test light source and the detection device are arranged in a common housing for placement above the test area. Integration into a common housing results in equal distances and identical alignments to the test area, making subsequent evaluation even easier and faster. Furthermore, the radiation direction and detection direction are synchronized in this way, further increasing the compactness of such a detection device.

[0025] In such a detection device according to the preceding paragraph, it is advantageous if the test light source is optically sealed from the detection device in the shared housing. Reflection elements, absorption elements, or similar elements can be used for this purpose. In other words, an optical short circuit between the test light source and the detection device is reliably prevented.

[0026] It can also be advantageous if, in a detection device according to the invention, the test light source is designed as an infrared light source and the detection device is designed as an infrared camera. As has already been explained several times, the design in the infrared range for the test light source and the detection device brings great advantages in terms of functional reliability and, at the same time, with regard to cost reduction. This also makes it possible to easily distinguish from visible light, in particular ambient light. The present invention also relates to a conveyor device for conveying trays for transporting objects, in particular in the form of hand luggage objects, comprising at least one detection device according to the invention.Thus, a conveying device according to the invention brings with it the same advantages as have been explained in detail with reference to a detection device according to the invention.

[0027] In a conveying device according to the invention and when using a detection device according to the invention, special trays are used in particular. These trays can have surfaces with increased roughness to prevent light reflections caused by natural and / or artificial ambient light. In this way, diffuse reflection can occur on such surfaces instead of point reflection, thus avoiding optical interference.

[0028] Furthermore, an object of the present invention is a detection method for detecting empty trays in such a conveyor device, for trays for transporting objects, comprising the following steps:

[0029] - Generating test light beams with a test light spectrum,

[0030] - polarizing the test light beams with a test polarizing filter with a first polarization angle,

[0031] - guiding the polarized test light beams into a test area,

[0032] - detecting reflection light rays reflected from the test area by means of a detection device behind a reflection polarization filter with a second polarization angle which differs from the first polarization angle,

[0033] - Determining objects in the test area based on polarized reflection light rays passing through the reflection polarization filter.

[0034] A detection method according to the invention offers the same advantages as those explained in detail with reference to a detection device according to the invention. When identifying objects, the captured images can be scanned, for example, point-by-point or line-by-line. This leads to the contour detection or perimeter detection of objects already explained several times, i.e., in particular, a purely two-dimensional representation of the captured image. At the same time, it is possible to detect with a high degree of certainty the absence of any objects and thus to define an empty tub.

[0035] As already explained, the inspection light beams can be generated and / or guided, particularly in a planar manner, as area light. This leads, as already described, to more uniform illumination and a reduction and / or elimination of optical disturbances such as reflections.

[0036] Furthermore, a detection method according to the invention also allows the use of spectral filters that have a transmission spectrum that corresponds or substantially corresponds to the test light spectrum. In this way, disturbing ambient light can be blocked out for the detection device.

[0037] It can be advantageous if, in a detection method according to the invention, known, particularly constant, contours are subtracted for the identification of objects. For example, trays can have structures that are identical for each tray. Printings are also possible whose surface structure allows the detection device to perceive them through the reflection polarization filter. This makes it possible to simply subtract these constant and thus known contours from the recorded image optically during the imaging process, thus making them inaccessible for further identification, so that the detection of empty trays can be carried out in the same simple, cost-effective, and rapid manner.

[0038] Further advantages are achieved if, in a recognition method according to the invention, at least one limit value is taken into account when determining objects, in particular with regard to the size of the objects and / or the brightness of the objects. This makes it possible to avoid false signals for very small objects or for reflections that do not originate from objects with a high degree of certainty. It is also advantageous if, in a recognition method according to the invention, an object signal is generated when at least one object has been determined and / or a false signal is generated if no object at all. This is particularly unspecific for objects and can simply mean outputting a signal. However, such signals can also be passed on as control information for the conveying device. This makes it possible, for example, for a tub to only leave the inspection area as an empty tub.A pictorial signal output, for example correlated with a color signal in red or green, can also enable a distinction between empty tubs and object tubs in a simple and quick way.

[0039] It is also advantageous if, in such a recognition process, at least one image is captured for each tub using the recognition device. Thus, one, and in particular exactly one, recognition photo is taken per tub, allowing the recognition steps to be performed simply and cost-effectively with minimal computational effort. Serial photos taken during retraction, thus tracing the tub's movement, are also conceivable. The interval for such photos can be, for example, in the range of 0.5 seconds.

[0040] It can also be advantageous if a recognition method according to the invention includes a step of determining the edges of objects and / or tubs. In this way, objects can be recognized and even defined based on their contour. The detection of tub edges can be based on defined alignment information. Particularly when the tubs are not conveyed into the recognition device in a defined guide, such detection of the alignment via edge detection can bring about a qualitative improvement in the recognition method. For the detection of tub edges, for example, an image analysis is conceivable which, in a first step, searches from a starting point within the tub boundaries outwards for an edge in the form of corresponding optical information.This is done in particular in two, for example arbitrary, directions so that two spaced-apart points on the tub edge can be detected. These edge points on the tub edge can then serve as a starting point for following the tub edge during the evaluation process, resulting in the tub edge being traced. This evaluation is carried out in particular using vectors that are set as starting points at the respective points and defined as direction and length for the evaluation algorithm. In this way, the entire recorded image no longer needs to be searched for edges. Instead, specific edge points are searched for from which the edges can be directly detected. The computational effort for this type of evaluation is significantly reduced compared to normal image evaluation of the entire image area.Similar methods, especially vector-based ones, are also conceivable for edge detection of other objects in the tank or separately from it. The described starting vectors can have a predefined length and / or direction. A predefined starting point is also conceivable to further simplify the process.

[0041] It is also advantageous if, in a detection method according to the invention, the steps of generating, polarizing, guiding, detecting, and determining are carried out at least partially on a tub moved through the inspection area by the conveyor device. For example, the entry of a tub into the inspection area can be detected using a position sensor as already explained. This can initiate the detection method, so that detection is carried out, in particular, until the identical or a different position sensor outputs a position signal indicating the movement of the tub out of the inspection area. The detection method can thus be synchronized with the movement of the tubs through a conveyor device.

[0042] Further advantages, features, and details of the invention will become apparent from the following description, which describes embodiments of the invention in detail with reference to the drawings. The features mentioned in the claims and in the description may be essential to the invention individually or in any combination. They show schematically:

[0043] Fig. 1 shows an embodiment of a detection device according to the invention,

[0044] Fig. 2 a representation of an empty tub,

[0045] Fig. 3 a representation of an object tray,

[0046] Fig. 4 shows a comparison of different spectra, Fig. 5 shows a further embodiment of a detection device according to the invention.

[0047] Figure 1 schematically shows a conveyor device 10, for example, at the end of a hand luggage scanning system. The detection device 10 is equipped with a check area PB, into which, in this side view, a tray W is retracted. To view into the tray W, the detection device 10 is arranged above the check area PB in a common housing 50. This is arranged at a defined check distance PA from the check area PB, so that when objects O are detected, they can be easily removed from the tray W.

[0048] To perform the detection, a light source 20 with a test illuminant 26 is provided in the detection device 10. This allows test light beams PL to be generated (Figure 1 shows a schematic of a light beam). With the help of guide devices 24, designed here as reflectors, all test light beams PL are guided through the test polarization filter 22 in the direction of the test area PB. The test light beams PL thus have a defined test light spectrum PS and a defined polarization according to the first polarization angle PW1. Depending on the reflection situation, i.e., at the empty bottom of the tank W or diffusely on objects O within the tank W, the reflected light RL is reflected back in the direction of the detection device 30 with an identical spectrum to the test light spectrum PS, but with a different polarization depending on the type of reflection.Only when the polarization of the reflected light beam RL has changed from the first polarization angle PW1 due to diffuse reflection can the reflected light beam RL at least partially pass through the reflected polarization filter 32 corresponding to the second polarization angle PW2. If this is the case, this is due exclusively to diffuse reflection from an object and is then, and only then, perceived by the detection device 30. The determination device 40 is now able to recognize the contour of any object based on the reflected light beams RL that have passed through, or to conclude the absence of any objects O in the well W based on the absence of any reflected light beams RL that have passed through. In this way, it is possible to distinguish empty wells LW from object wells OW very easily, quickly, and with little computation, without having to perform specific object detection.

[0049] This evaluation is explained in more detail with reference to Figures 2 and 3. In both cases, an embodiment according to Figure 1 is involved. Here, it can be clearly seen that the first polarization angle PW1 differs from the second polarization angle PW2, rotated by 90°. This means that in the case of an empty tub, as empty tub LW according to Figure 2, only contours of the tub W are perceived. If this expected constant contour of the tub W can now be optically subtracted, this results in the determination device 40 recognizing the empty tub LW as such and outputting a false signal FS. In contrast, the tub W in Figure 3 contains an object 0, for example a boarding pass.This results in the test light rays PL being reflected, at least at the edges of this flat object 0, such that their polarization changes and they are thus able to at least partially penetrate the reflection polarization filter 32. The detection device 30 thus reproduces an image, as shown in Figure 3, with the contours of the detected object 0, according to the reflected light rays RL that have passed through. Here, too, it is possible to subtract the contours of the tub W, which are also constant and known, so that only the contour of the object 0 remains. On this basis, the determination device 40 now outputs the object signal OS.

[0050] Figure 4 also shows how the individual spectra can be configured relative to one another. For example, an ambient light spectrum US has a broad peak in the visible range. The test light spectrum PS is preferably very narrow-band in the infrared range, for example, with a peak width of 10 nanometers. In this variant, it is also clearly visible that the intensity of the test spectrum PS lies above the ambient light as the ambient spectrum US, thus outshining it.

[0051] Figure 5 shows a further development of the embodiment of the detection device 10. This now has a plurality of test illuminants 26 in the test light source 20. These are arranged to the left and right around a central detection device 30. The detection device 30 is optically sealed from the test light source 20. Furthermore, all test illuminants 26 are provided with a uniform radiation direction SR, which here is aligned opposite a detection direction as the radiation direction SR for the detection device 30. This results in a uniform and uniform irradiation of the test area (not shown here) and central detection in the detection device 30. To further improve detection, a reflection spectral filter 36 is arranged in the beam path downstream of the reflection polarization filter 32.This serves to filter out ambient light, as its transmission spectrum essentially corresponds to the test light spectrum PS.

[0052] The above explanation describes the present invention exclusively by way of examples. Of course, individual features of the embodiments can be freely combined with one another, provided they are technically feasible, without departing from the scope of the present invention.

[0053] List of reference symbols

[0054] 10 Detection device

[0055] 20 Test light source

[0056] 22 test polarizing filters

[0057] 24 Guide device

[0058] 26 test lamps

[0059] 30 Detection device

[0060] 32 reflection polarizing filters

[0061] 36 reflection spectral filters

[0062] 40 Determination device

[0063] 50 housings

[0064] 100 conveyor device

[0065] PL test light beams

[0066] PS test light spectrum

[0067] US ambient light spectrum

[0068] PW1 first polarization angle

[0069] PW2 second polarization angle

[0070] PB test area

[0071] PA test distance

[0072] RL Reflected light rays

[0073] SR radiation direction

[0074] W tub

[0075] O Object

[0076] LW empty tub

[0077] OW object tub

[0078] OS object signal

[0079] FS false signal

Claims

Patent claims 1. Detection device (10) for detecting empty trays (LW) in a conveyor device (100) for trays (W) for transporting objects (O), comprising a test light source (20) for generating test light beams (PL) with a test light spectrum (PS) with a test polarization filter (22) with a first polarization angle (PW1) and a guide device (24) for guiding the test light beams (PL) through the test polarization filter (22) into a test area (PB), further comprising a detection device (30) for detecting reflection light beams (RL) reflected from the test area (PB) with a reflection polarization filter (32) with a second polarization angle (PW2) which differs from the first polarization angle (PW1),further comprising a determination device (40) for determining objects (O) in the test area (PB) on the basis of polarized reflection light rays (RL) passing through the reflection polarization filter (32).

2. Detection device (10) according to claim 1, characterized in that the first polarization angle (PW1) and the second polarization angle (PW2) are aligned at 90° or substantially 90° to each other.

3. Detection device (10) according to one of the preceding claims, characterized in that the test light source (20) generates the test light rays (PL) in a test light spectrum (PS) in the range invisible to the human eye, in particular in the infrared range.

4. Detection device (10) according to one of the preceding claims, characterized in that the test light source (20) has a plurality of individual test illuminants (26) which in particular have rectified or substantially rectified radiation directions (SR). Detection device (10) according to one of the preceding claims, characterized in that the test light source (20) generates the test light beams (PL) with a brightness above the brightness of the ambient light. Detection device (10) according to one of the preceding claims, characterized in that a reflection spectral filter (36) with a transmission spectrum that corresponds or substantially corresponds to the test light spectrum (PS) is arranged in the beam path in front of the detection device (30). Detection device (10) according to one of the preceding claims, characterized in that it has the test area (PB) for temporarily receiving trays (W) of the conveyor device (100), in particular the test area (PB) forms a section of the conveyor device (100).Detection device (10) according to claim 7, characterized in that a test distance (PA) is formed between the test light source (20) and the detection device (30) on one side and the test area (PB) on the other side. Detection device (10) according to one of claims 7 or 8, characterized in that the test area (PB) has a position sensor for detecting a tub (W) conveyed into the test area (PB) by means of the conveying device (100). Detection device (10) according to one of the preceding claims, characterized in that the test light source (20) and the detection device (30) are arranged in a common housing (50) for placement above the test area (PB). Detection device (10) according to claim 10, characterized in that in the common housing (50), the test light source (20) is optically sealed from the detection device (30). Detection device (10) according to one of the preceding claims, characterized in that the test light source (20) is designed as an infrared light source and the detection device (30) is designed as an infrared camera. A conveyor device (100) for conveying trays (W) for transporting objects (O), in particular in the form of hand luggage, comprising at least one detection device (10) with the features of one of claims 1 to 12. A detection method for detecting empty trays (LW) in a conveyor device (100), in particular with the features of claim 13, for trays (W) for transporting objects (O), comprising the following steps: - Generation of test light beams (PL) with a test light spectrum (PS), - polarizing the test light beams (PL) with a test polarization filter (22) with a first polarization angle (PW1), - guiding the polarized test light beams (PL) into a test area (PB), - detecting reflection light rays (RL) reflected from the test area (PB) by means of a detection device (40) behind a reflection polarization filter (32) with a second polarization angle (PW2) which differs from the first polarization angle (PW1), - Determining objects (O) in the test area (PB) based on polarized reflected light rays (RL) that have passed through the reflection polarization filter (32). A detection method according to claim 14, characterized in that known, in particular constant, contours are subtracted for determining objects (O). Recognition method according to one of claims 14 or 15, characterized in that when determining objects (0), at least one limit value, in particular with regard to the size of the objects (0) and / or the brightness of the objects (0), is taken into account. Recognition method according to one of claims 14 to 16, characterized in that upon successful determination of at least one object (0), an object signal (OS) is generated and / or if no object (0) at all is missing, a false signal (FS) is generated. Recognition method according to one of claims 14 to 17, characterized in that for each trough (W), at least one image is recorded with the recognition device (40). Recognition method according to one of claims 14 to 18, characterized in that a step of determining edges of objects (0) and / or troughs (W) is carried out.Recognition method according to one of claims 14 to 19, characterized in that the steps of generating, polarizing, guiding, detecting and determining are carried out at least partially on a trough (W) moved through the test area (PB) with the conveyor device (100).

Images