STOVRING, Knud (Brentebjerg 4, Asperup, DK-5466, DK)
Claims
1. An apparatus for counting and/or sorting objects, in particular recyclable beverage containers, such as bottles or cans, said apparatus comprising
a receiving section from which the objects are forwarded on conveyor means to a recording unit and subsequently forwarded for counting and/or sorting, said recording unit comprising a scanning plane generally perpendicular to the direction of travel of the objects, and
at least one photoelectric sensor unit provided in said scanning plane for registering the presence of an object in the scanning plane, said at least one photoelectric sensor unit comprising at least one transmitter part comprising at least one light emitting unit for emitting light towards the objects, and at least one receiver part for receiving the light emitted from the at least one transmitter part,
the apparatus characterized in that
the at least one photoelectric sensor unit is self-adjustable, preferably by continuously adjusting the characteristics of the at least one light emitting unit to compensate for degraded reflection characteristics of the at least one photoelectric sensor unit.
2. An apparatus according to claim 1 , wherein the at least one transmitter part and the at least one receiver part is located substantially opposite each other, whereby light emitted from the transmitter part is received in the receiver part.
3. An apparatus according to claim 1 , wherein at least one mirror is located opposite the at least one transmitter part and the at least one receiver part, whereby light emitted from the transmitter part is reflected in the at least one mirror back into the receiver part.
4. An apparatus according to any of the preceding claims, wherein a plurality of cameras is arranged in the scanning plane.
5. An apparatus according to any of the preceding claims, wherein at least part of the recyclable beverage containers are provided with at least one visibly detectable identification marking, whereby the beverage containers can be identified by means of scanning the at least one identification marking.
6. An apparatus according to any of the preceding claims, wherein at least two photoelectric sensor units are provided with an angular displacement in the scanning plane, said angular displacement preferably being between 45-135°
7. An apparatus according to any of the preceding claims, wherein the at least one photoelectric sensor unit comprise an automatic contrast tracking system, whereby resetting of said photoelectric sensor can be provided, preferably at regular intervals.
8. An apparatus according to any of the preceding claims, wherein the level of light emitted from the photoelectric sensor unit is automatically adjusted appropriate to provide detection of any object interrupting the light beam.
9. A method for counting and/or sorting objects, in particular recyclable beverage containers, such as bottles or cans, said method comprising the steps of:
- forwarding the object by means of conveyors from a receiving section to a recording unit, said recording unit comprising a scanning plane generally perpendicular to the direction of travel of the objects,
- registering the presence of an object in the scanning plane by means of at least one photoelectric sensor unit provided in said scanning plane, said at least one photoelectric sensor unit comprising - at least one transmitter part comprising at least one light emitting unit for emitting light towards the objects, and at least one receiver part for receiving the light emitted from the transmitter part, said at least one photoelectric sensor unit being self-adjustable, preferably by continuously adjusting the characteristics of the at least one light emitting unit to compensate for degraded reflection characteristics of the at least one photoelectric sensor unit, and - forwarding the objects for counting and/or sorting by means of conveyors.
10. A method according to claim 9, wherein the at least one transmitter part and the at least one receiver part is located substantially opposite each other, whereby light emitted from the transmitter part is received in the receiver part.
11. A method according to claim 9, wherein at least one mirror is located opposite the at least one transmitter part and the at least one receiver part, whereby light emitted from the transmitter part is reflected in the at least one mirror back into the receiver part.
12. A method according to any of the claims 9 to 11 , wherein a plurality of cameras is arranged in the scanning plane.
13. A method according to any of the claims 9 to 12, wherein at least part of the recyclable beverage containers are provided with at least one visibly detectable identification marking, whereby the beverage containers can be identified by means of scanning the at least one identification marking.
14. A method according to any of the claims 9 to 13, wherein at least two photoelectric sensor units are provided with an angular displacement in the scanning plane, said angular displacement preferably being between 45-135°
15. A method according to any of the claims 9 to 14, wherein the at least one photoelectric sensor unit comprise an automatic contrast tracking system, whereby resetting of said photoelectric sensor can be provided, preferably at regular intervals.
16. A method according to any of the claims 9 to 15, whereby the level of light emitted from the photoelectric sensor unit is automatically adjusted appropriate to provide detection of any object interrupting the light beam. |
Apparatus and method for counting, identifying and/or sorting objects
The present invention relates to an apparatus and a method for counting, identifying and/or sorting objects, in particular recyclable beverage containers, such as bottles or cans.
An apparatus for such a method is known from WO 2006/125436, wherein packages are forwarded sequentially through a recording unit and an identification marking on each package is detected by one or more cameras and compared to a reference value whereby information about the package may be determined. The apparatus furthermore comprises one or more detectors, which are used for determining the presence of the objects in the recording unit of the apparatus.
In the recording unit, the detector means are positioned in the scanning plane perpendicular to the axis of movement of the objects in between the cameras in the annular ring with the objects on the conveyor means substantially in the centre of this scanning circle. The detector means are either photoelectric sensors with combined transmitter and receiver parts where the transmitter part emits light towards the objects and associated mirrors are positioned opposite the light emitting sensors reflecting the light back into the receiver part or separate transmitter and receiver parts where the transmitter emits light towards the object and is detected by the receiver part positioned opposite to the transmitter part.
It is important to keep the detector parts clean in order to safeguard the function of the detectors. In sorting return beverage containers, residues of fluids in the cans and bottles often escape during the processing of the containers in the apparatus which accumulates inside the apparatus and in particular the recording unit. In relation to recording recycled beverage containers in a reverse vending system, the detector parts must often be cleaned or otherwise the detectors fail to record the presence of a container which is then not recorded and no refund is paid. In order to ensure the reliability of the apparatus, the detector parts are cleaned by an operator on a regular basis, often several times per day.
However, by the invention it is realised that the need for this manual cleaning in order to ensure the accuracy of the apparatus may be decreased. Accordingly, the invention
concerns an apparatus for counting and/or sorting objects, in particular recyclable beverage containers, such as bottles or cans, said apparatus comprising a receiving section from which the objects are forwarded on conveyor means to a recording unit and subsequently forwarded for counting and/or sorting, said recording unit comprising a scanning plane generally perpendicular to the direction of travel of the objects, and at least one photoelectric sensor unit provided in said scanning plane for registering the presence of an object in the scanning plane, said at least one photoelectric sensor unit comprising at least one transmitter part comprising at least one light emitting unit for emitting light towards the objects, and at least one receiver part for receiving the light emitted from the at least one transmitter part, the apparatus characterized in that the at least one photoelectric sensor unit is self-adjustable, preferably by continuously adjusting the characteristics of the at least one light emitting unit to compensate for degraded reflection characteristics of the at least one photoelectric sensor unit.
Furthermore, the invention regards a method for counting and/or sorting objects, in particular recyclable beverage containers, such as bottles or cans, said method comprising the steps of:
- forwarding the object by means of conveyors from a receiving section to a recording unit, said recording unit comprising a scanning plane generally perpendicular to the direction of travel of the objects,
- registering the presence of an object in the scanning plane by means of at least one photoelectric sensor unit provided in said scanning plane, said at least one photoelectric sensor unit comprising
- at least one transmitter part comprising at least one light emitting unit for emitting light towards the objects, and
- at least one receiver part for receiving the light emitted from the transmitter part, said at least one photoelectric sensor unit being self-adjustable, preferably by continuously adjusting the characteristics of the at least one light emitting unit to compensate for degraded reflection characteristics of the at least one photoelectric sensor unit, and
- forwarding the objects for counting and/or sorting by means of conveyors.
In further embodiment of the invention at least one mirror is located opposite the at least one transmitter part and the at least one receiver part, whereby light emitted from
the transmitter part is reflected in the at least one mirror back into the receiver part. The transmitter part and the receiver part are thereby preferably located together whereby the photoelectric sensor unit can be substantially one component. The disadvantage is that the mirror is an additional recipient of dust, filth and liquids in addition to the transmitter and the receiver parts.
In yet another embodiment of the invention the at least one transmitter part and the at least one receiver part is located substantially opposite each other, whereby light emitted from the transmitter part is received in the receiver part.
With the method and the apparatus according to the invention, almost any object that enters the recording unit can be detected and thereby counted. However, to provide a detailed counting and sorting of the objects, identification of the objects must be provided. Thus, in a preferred embodiment of the invention a plurality of cameras is arranged in the scanning plane. Furthermore, at least part of the recyclable beverage containers are provided with at least one visibly detectable identification marking, whereby the beverage containers can be identified by means of scanning the at least one identification marking, preferably by means of cameras. An identification marking may also be identified by means of one or more scanners, such as bar code scanners. Thus, cameras in the recording unit may be replaced or supplied by one or more scanners.
In a further embodiment of the invention more than one scanning plane is provided. Recording unit(s) can be provided in each scanning plane to decrease the risk of not registering objects. Cameras can be provided in each scanning plane to decrease the risk of not identifying objects. Cameras may be in one scanning plane and recording unit(s) in another scanning plane.
To increase the probability of detecting objects in the detector unit, more than one sensor unit can be provided, preferably distributed in the scanning plane. In a preferred embodiment of the invention, at least two photoelectric sensor units are provided with an angular displacement in the scanning plane, said angular displacement preferably being between 45-135°. The use of two sensor units in the scanning plane in the recording unit means that transparent containers, such as water bottles of transparent plastic, may be detected from different angles, whereby the risk of missing detection of
containers is further decreased, even if the emitted light from one of the sensor units passes through the transparent bottle and is received by the receiving part of the sensor.
The conditions inside the recording unit may change during operation. Humidity, temperature, dirt, filth, dust, liquids and the like may change the operating conditions as well as influencing lenses, mirrors, light sources and other sensitive components. A way of correcting for the changing conditions is to monitor the contrast in the recording unit and adjust the sensor when the contrast changes and/or how the contrast changes. In one embodiment of the invention an automatic contrast tracking system is comprised. Thereby e.g. resetting of said photoelectric sensor can be provided. This resetting can be provided at regular intervals or when a change is detected by the contrast tracking system.
The sensor unit can furthermore compensate for varying conditions by adjusting the level of emitted light. The photoelectric sensor unit can preferably automatically adjust the level of emitted light just appropriate to provide detection of almost any object in the light beam. This can for example be provided by an automatic calibration procedure, preferably provided in a short period without objects in the light beam between the transmitter and the receiver. This calibration procedure may include comparing the level of light detected by the receiver with and without a predefined object, item, foil or the like in the light beam, said object, item, foil or the like having known light transparency. Thereby the receiver sensitivity and/or the level of emitted light can be adjusted to automatically calibrate the sensor unit. This calibration procedure may be provided at regular intervals and/or when a change in operating condition is detected.
A particular embodiment of the invention is an apparatus for identifying objects for sorting the objects, in particular recyclable beverage containers, such as bottles or cans, which are provided with at least one visibly detectable identification marking, said apparatus comprising a receiving section from which the objects are forwarded on conveyor means to a recording unit and after the recording the objects are forwarded for sorting, said recording unit comprises a plurality of cameras arranged in a scanning plane generally perpendicular to the direction of travel of the objects, at least one photoelectric sensor unit is provided in said scanning plane for registering the presence of an object in the scanning plane, said photoelectric sensor unit comprises a light
emitting and receiving unit and a reflector unit provided opposite said light emitting unit, wherein the light emitting unit of the sensor unit is self-adjustable so that said light emitting unit of the sensor unit continuously adjusts the characteristics of the light emitting unit to compensate for degraded reflection characteristics of the photoelectric sensor unit.
Yet another embodiment of the invention is an apparatus for identifying objects for sorting the objects, in particular recyclable beverage containers, such as bottles or cans, which are provided with at least one visibly detectable identification marking, said apparatus comprising a receiving section from which the objects are forwarded on conveyor means to a recording unit and after the recording the objects are forwarded for sorting, said recording unit comprises a plurality of cameras arranged in a scanning plane generally perpendicular to the direction of travel of the objects, at least one photoelectric sensor unit is provided in said scanning plane for registering the presence of an object in the scanning plane, said at least one photoelectric sensor unit comprising at least one transmitter part comprising at least one light emitting unit for emitting light towards the objects, and at least one receiver part for receiving the light emitted from the at least one transmitter part, the at least one photoelectric sensor unit is self-adjustable, preferably by continuously adjusting the characteristics of the at least one light emitting unit to compensate for degraded reflection characteristics of the at least one photoelectric sensor unit.
By using a self-adjusting photoelectric sensor for object detection in the recording unit, the degradation of the reflected light signal from the transmitter part, the reflector part or the receiver part may be adjusted for. This means that less manual cleaning is required. Hereby dirt covers on the reflectors may be automatically adjusted for.
Detailed description of the invention
There can be two different applications of the method and the apparatus according to the invention:
1. The typical application used in most countries in reverse vending systems, is where the total refund is based on counting the beverage containers and detecting one or more identification markings (bar codes and/or security
markings) on the beverage container. For each container counted there must be associated one or more identification markings to validate the total refund.
2. Simple applications (e.g. in countries where no national bar code database is available) where the total refund is based on simply detecting and counting the containers without reading any identification markings on the beverage containers. In this application the beverage containers can not be sorted, because the information about material type is typically retrieved from a database with the identification markings as entry keys.
The invention is described in the following with reference to the drawings in which:
Fig. 1 is a schematic view of one embodiment of an apparatus according to the invention used in a recording and sorting apparatus; fig. 2 is a schematic side view of a recording unit in one embodiment of an apparatus according to the invention; and fig. 3 is a schematic front view of the recording unit in fig. 2.
With reference to figure 1 , the this particular embodiment of the invention relates to a recording and sorting apparatus for handling recycled objects 1 , in particular beverage containers such as bottles of various plastic materials and cans of aluminium or steel, in particular beverage containers 1 that are part of a return vending system. Returned objects 1 are collected and filled into a container 10 and forwarded along a conveyor section 11 comprising a plurality of conveyors in series and through a recording unit 12 for identifying the objects 1. The objects 1 are forwarded into the recording unit 12 on a first conveyor 15 and out of the recording unit 12 on a second conveyor 16 to a sorting section 13 where the packages 1 are sorted according to one or more characteristics detected in the recording unit 12 and recorded and processed in a control system 14.
With reference to fig. 2, there is a small gap 17 between the first conveyor 15 and the second conveyor 16. The scanning plane S is provided in this gap 17 and the cameras 2 in the recording unit 12 are arranged on a circle (see fig. 3) having a centre on the longitudinal axis of the objects 1. Rotation of the package is hereby not required in order to read the identification markings 5 on the objects 1. This reduces the handling
time in the recording unit and thereby considerably increasing the capacity of the apparatus for recording and sorting in a recycling system.
Each object 1 is provided with an identification marking 5, such as a bar code and possibly also a security marking 6 verifying that the identification marking 5 is authentic. The identification marking 5 and the security sign 6 are scanned by the cameras 2. In the scanning plane S two photoelectric sensor units 3, 4 are furthermore provided.
In one embodiment of the invention each sensor unit comprises a photoelectric sensor with combined transmitter and receiver parts 3 where the transmitter part emits light towards the objects and associated mirrors 4 are positioned opposite the light emitting sensors reflecting the light back into the receiver part.
I another embodiment of the invention each sensor unit comprises separate transmitter and receiver parts where the transmitter part 3 emits light towards the object and is detected by the receiver part 4 positioned opposite to the transmitter part,
In a preferred embodiment of the invention the light emitting unit 3 of the sensor unit is self-adjustable by continuously adjusting the characteristics of the emitted light to compensate for degraded reflection characteristics of the photoelectric sensor unit.
In the preferred embodiment of the invention two sensor units 3, 4 are provided with a mutual angular displacement in the scanning plane, such as an angular displacement between 45-135° (see fig. 3). The use of two sensor units 3, 4 in the scanning plane S in the recording unit 12 means that transparent containers 1 , such as water bottles of transparent plastic, may be detected from different angles, whereby the risk is eliminated that no container is detected even if the emitted light from one of the sensor units 3, 4 passes through the transparent bottle and is reflected back by the mirror back through the transparent bottle.
When the sensor units 3, 4 are installed, the sensor units may automatically adjust for condition changes, such as dirt on the lenses or reflectors in the sensor units 3, 4. This adjustment may be achieved because the sensors 3 include an automatic contrast tracking system so that the sensor is capable of resetting itself at regular intervals.
Detailed description of the self adjusting photo sensor
A traditional photo sensor is implemented in basically 2 ways:
1 : The photo sensor comprises a single unit, which comprises a transmitting part and a receiving part. The transmitting part emits light towards the object to be detected and is reflected by a mirror, preferably positioned diagonally and substantially opposite to the transmitter behind the object to be detected. When no object is present the light transmitted by the transmitter is travelling uninterrupted from the transmitter to the mirror and back to the receiving part of the photo sensor. When an object is present the light beam is interrupted and no (or less) light passes back to the receiving part of the photo sensor.
2: The photo sensor comprises two units, a transmitting part and a receiving part. The transmitting part emits light towards the object to be detected. When no object is present the light transmitted by the transmitter is travelling uninterrupted from the transmitter to the receiving part and will be detected by the receiving part. When an object is present the light beam is interrupted and no (or less) light passes from the transmitting part to the receiving part of the photo sensor.
In both cases the light emitted by the transmitting part can be diffused or focused light, monochromatic or broadband light, modulated or un-modulated light, polarised or un- polarised light.
The detection of especially beverage containers made of different transparent plastic materials such as PET, is difficult as the material transmits nearly 100% light. This means that the percentage of light received by the receiver is nearly the same whether there is an object between the photo sensor and the mirror or the transmitting part and the receiving part of the photo sensor. This requires a photo sensor with high sensitivity, i.e. a sensor which can detect whether a transparent bottle or dust and filth is in the light beam
Traditional photo sensors which are not self adjusting have to be adjusted manually prior to operation. This is normally done as follows: Without any object between the
transmitter and the receiver the level of light emitted by the transmitter is adjusted manually so the receiver just receives enough light to detect "no object" in the light beam. Next a sheet of nearly transparent foil is placed between the transmitter and the receiver and the level of light emitted by the transmitter is adjusted again manually so the level of light received by the receiver is just insufficient to detect "no object" in the light beam. In more clear terms the photo sensor is ON when there is no object in the light beam, and the photo sensor is OFF when there is an object in the light beam.
The level of light received by the receiver part of the photo sensor now depends on the setting of the light level, which has been done manually plus contribution from the following parameters:
Dirt, scratches or dust on the surface of the transmitter part of the photo sensor. Dirt, scratches or dust on the surface of the mirror. • Dirt, scratches or dust on the surface of the receiving part of the photo sensor.
I a preferred embodiment of the invention handling of beverage containers is provided, which have been subject to transport and handling. The majority of beverage containers delivered back are not even empty at the time when they are processed by the apparatus. This means that the dirt, dust and remaining liquids will to some extent be left in the apparatus during processing and consequently also hit some parts of the photo sensor. This means that over time the characteristics of the photo sensor change and the photo sensor must be re-adjusted manually.
The present invention is based on a so-called "self adjusting photo sensor" which operates as follows:
Once installed the self adjusting photo sensor will during power up preferably perform an automatic calibration equivalent to the manual adjustment procedure explained above. The self adjusting photo sensor will automatically set the level of light just appropriate to detect "object" or "no object" in the light beam.
During operation the self adjusting photo sensor will basically be subject to the same kind of degradation caused by dirt, dust and remaining liquids in the beverage containers as is the case with the traditional photo sensor.
However, the self adjusting photo sensor is able to continuously perform the self adjusting / calibration procedure. When "no object" has been detected for a while, the self adjusting photo sensor will preferably perform the calibration procedure and thereby eliminate the effect of the degradation build up since the last calibration procedure took place. The calibration procedure may only last a few milliseconds and will not interfere with the basic operation of the apparatus.
The self adjusting photo sensor according to the invention automatically adapts to the environment and the changes in the operating conditions whereas a traditional photo sensor will require manual intervention on a regular basis to maintain the operational quality of the apparatus. With the requirements to the sensitivity and efficiency of modern return vending systems, a photo sensor requiring manual intervention is not applicable.
The invention is described above with reference to a several embodiments. However, it is realised that other suitable solutions may be provided without departing from the scope of the invention as defined in the accompanying claims.
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