WO2009002156A1

WO2009002156A1 - Device for identifying pieces of luggage provided with an rfid tag

Info

Publication number: WO2009002156A1
Application number: PCT/NL2008/000162
Authority: WO
Inventors: Herman Johan Krijt; Wijnand Van Gils
Original assignee: Vanderlande Industries Nederland B.V.
Priority date: 2007-06-28
Filing date: 2008-06-25
Publication date: 2008-12-31

Abstract

The present invention provides a device for identifying products, such as pieces of luggage or parcels, provided with an RFID tag, comprising a conveyor for conveying the products along a conveying path, a tunnel, through the interior of which said conveying path extends, means for generating, in a central zone of the tunnel, electromagnetic microwave radiation reaching outside the tunnel, which generated electromagnetic microwave radiation may have several modes, at least one RFID antenna inside the tunnel for reading information stored on an RFID tag associated with a product present in the tunnel. At least part of at least one wall of the tunnel defining the interior of the tunnel is tapered from the central zone towards at least one end of the tunnel, such that said at least one end of the tunnel prevents the electromagnetic microwave radiation from reaching outside the tunnel.

Description

Device for identifying pieces of luggage provided with an RFID tag.

DESCRIPTION

The present invention relates to a device for identifying products, such as pieces of luggage or parcels, provided with an RFID tag, comprising a conveyor for conveying the products along a conveying path, a tunnel, through the interior of which said conveying path extends, means for generating, in a central zone of the tunnel, electromagnetic microwave radiation reaching outside the tunnel, which generated electromagnetic microwave radiation may have several modes, at least one RFID antenna inside the tunnel for reading information stored on an RFID tag associated with a product present in the tunnel.

To monitor the logistic process involved in the handling of pieces of luggage, in particular at airports, but also in the handling of parcels in sorting centres for so-called express parcel distribution, the current trend is to provide such products with an RFID tag, the more so now that the price of such RFID tags has decreased considerably the last few years. Unique codes and thus information associated with the product in question can thus be read, using radio waves, by an RFID reader comprising at least one RFID antenna as well as a decoder. RFID tags offer a number of significant advantages over bar codes, such as the fact that a direct line of vision between the RFID antenna and the RFID tag is no longer required, a reduced sensitivity to dirt or creases and larger distances over which information can be transferred. On account of these advantages, the reliability with which products can be identified by means of RFID tags is typically higher than in the situation in which bar codes are used. A device as referred to in the introduction is known from

International patent application WO-A1-02/15115. Said publication describes a luggage handling system in which a belt conveyor for pieces of luggage extends through a tunnel. The tunnel has two flat, vertical side walls and a flat, horizontal upper wall connecting said side walls. A flat, rectangular RFID antenna is provided on one of the side walls. Although the reliability with which pieces of luggage provided with an RFID tag can be identified by means of such a device is higher than the reliability with which pieces of luggage provided with a bar code can be identified by means of a bar code reader, the object of the invention is to enhance the detection reliability even further. What plays a part in this regard is that in practice the detection range of the RFID antenna extends beyond the tunnel in some cases, as a result of which pieces of luggage located outside the tunnel are identified instead of pieces of luggage that may be present inside the tunnel, which may lead to incorrect identification. Because of this problem it is known to use curtains at the entrance and/or the exit of the tunnel. Said curtains in turn have been found to interfere with signals. Furthermore it is known to use an absorbent material inside the tunnel so as to minimise reflections within the tunnel. In addition to that it has been found that pieces of luggage, but also any metal that may form part of the piece of luggage, may interfere with the generated field of radio waves, making it more difficult to read the RFID tags.

The present invention is characterised in that at least part of at least one wall of the tunnel defining the interior of the tunnel is tapered from the central zone towards at least one end of the tunnel, such that said at least one end of the tunnel prevents the electromagnetic microwave radiation from reaching outside the tunnel.

As a result of the specific taper of the walls of the tunnel in the direction of the tunnel ends, any outward flow (or propagation) of electromagnetic microwave radiation generated inside the tunnel is so impeded that no radio waves will be detected outside the tunnel. In this way RFID tags attached to pieces of luggage located outside the tunnel are prevented from being activated by said radiation and emitting the RFID information stored thereon/therein. This leads to an improved luggage handling system exhibiting a higher degree of reliability and accuracy.

Accordingly, the invention relates to the detection and identification of only one RFID tag present inside the tunnel and consequently preventing situations in which several RFID tags present outside the tunnel are activated as well and in which identification signal emitted by said activated RFID tags is detected by the detection antenna disposed inside the tunnel.

In this way the risk of products present outside the tunnel being detected is significantly reduced, whilst on the contrary the chance of detection inside the tunnel is increased, so that there is a greater chance of detection and a correct readout of the RFID tag inside the tunnel. For a correct understanding of the purpose of the invention it should be realised that the term "wall" is to be understood to refer not only to the vertical walls of a tunnel, but also to horizontal walls, such as in particular the ceiling of the tunnel and the bottom of the tunnel.

The confining of the radio waves within the interior of the tunnel can be further improved if at least part of at least one wall of the tunnel defining the interior of the tunnel is tapered towards two opposite ends of the tunnel and/or if at least two parts of two respective opposite walls of the tunnel defining the interior of the tunnel are tapered towards at least one end of the tunnel.

Taking into consideration the fact that in principle radio waves are emitted perpendicularly from the RFID antenna, it is furthermore preferable if said at least one RFID antenna is provided on one wall of the tunnel, whilst at least part of the opposite tunnel wall is tapered towards at least one end of the tunnel.

In particular in order to read RFID tags present on the underside of a product with a higher greater degree of reliability, it is furthermore advantageous if an RFID antenna is provided below the level of a product passing through the tunnel. For constructional reasons it is advantageous if the tunnel has a constant cross-section along a part of the length of the tunnel that is spaced from the ends of the tunnel. Thus, the tunnel only has the aforesaid taper form at the ends thereof.

The construction of the tunnel can further be realised in a simple manner if said taper is a rectilinear taper, thus making it possible to form the walls from a flat sheet material by means of comparatively simple tools.

WO 99/49337 further discloses a device for identifying products, such as pieces of luggage or parcels, provided with an RFID tag. Said device employs a static magnetic field, which is generated in the tunnel. Said magnetic field induces so-called "eddy currents" in the metallic wall parts of the tunnel, which eddy currents will flow through the wall parts and which are considered to interfere with the. correct operation of the device. To that end the walls of the tunnel are lined with a high permeability magnetic material, such as ferrite.

WO 99/49337 does not disclose a specific tapered tunnel end, which prevents the electromagnetic microwave radiation from exiting the tunnel.

JP-2006252181 furthermore discloses a device for simultaneous identification of several products provided with an RFID tag, which products are present in a tunnel space. In order to be able to detect all the RFID tags in an adequate manner, the tunnel is provided with a rotating bottom plate. Thus, the RFID tags of the several products placed on the rotating bottom plate can be effectively activated by the means that generate electromagnetic microwave radiation.

In order to be able to detect all the identification signals emitted by the activated RFID tags, reflectors are provided in the tunnel walls, which reflectors reflect the RFID signals in the direction of the detection antenna. The object of the device according to JP-2006252181 is to identify several RFID tags and prevent undesirable situations in which one or more activated RFID tags are not read.

US 2006/0170556 discloses a device for identifying products provided with an RFID tag. The tunnel space has excessive constructional dimensions that determine the characteristics of the electromagnetic radiation generated in the tunnel.

The invention will be explained in more detail hereinafter by means of a description of a number of preferred embodiments of a device according to the invention, in which reference is made to the following figures:

Figure 1 is a perspective view of the first preferred embodiment of a device according to the invention;

Figures 2a, 2b and 2c are a top plan view, a side view and a front view, respectively, of the device of figure 1 ; Figure 3 is a perspective view of a second preferred embodiment of a device according to the invention;

Figure 4 is a front view of the device of figure 3;

Figure 5 is a perspective view of the tunnel forming part of a third preferred embodiment of a device according to the invention; Figures 6a and 6b are a top plan view and a side view, respectively, of the third preferred embodiment;

Figure 7 is a perspective view of a tunnel forming part of a fourth preferred embodiment of a device according to the invention;

Figures 8a and 8b are a top plan view and a side view, respectively, of the fourth preferred embodiment; and

Figures 9a and 9b show the electromagnetic field generated in the tunnel at various distances from the centre plane of the tunnel in the direction of the ends thereof.

Figure 1 shows a device 1 for identifying pieces of luggage 2 provided with an RFID tag 3 that forms part of a label 4 which was attached to a handle 5 of pieces of luggage 2 when said pieces of luggage 2 were checked in.

The device 1 comprises a belt conveyor 6 as well as a tunnel 7. The belt conveyor 6 conveys pieces of luggage 2 through the tunnel 7 in the conveying direction 15. The tunnel 7 comprises two vertically opposite side walls 8, 9 and an upper wall 10, which upper wall connects the upper edges of the side walls 8, 9. Flat RFID antennas 11 , 12, 13 are provided in or on the walls 8, 9 and 10, which antennas form part of an RFID reader in combination with a decoder. The decoder may be integrated in an RFID antenna, as it were, but it may also be a separate component, which may be located outside the tunnel 7. RFID readers are known per se to those skilled in the art and require no further explanation.

The tunnel 7 further comprises a flat bottom plate 14 of plastic material, which is disposed directly below the load-supporting part of the belt conveyor 6. The bottom plate 14 forms a locally heightened portion of the belt conveyor 6. The bottom plate 14 extends over the entire width of the belt associated with the conveyor 6 and also over (practically) the entire length of the tunnel 7. A further RFID antenna (not shown), hereinafter indicated by numeral 16, is mounted in the bottom.

Seen in the conveying direction 15, three zones can be distinguished for the walls 8, 9, 10, and thus for the tunnel 7 as a whole, which zones are indicated by Roman numerals I₁ Il and III in figure 2a. The tunnel 7 has a constant cross-section in the central zone II, seen in the conveying direction 15. In zones I and III the walls 8, 9, 10 are tapered towards the associated end of the tunnel 7. The walls 8, 9, 10 extend rectilinearly within the zones I and III. Because of the aforesaid taper of the zones I and III of the walls 8, 9, 10, the tunnel 7 as a whole also exhibits a taper in the aforesaid zones I, III.

Consequently it has been found in practice that the radio waves emitted by RFID antennas 11 , 12, 13 and 16 remain confined within the interior of the tunnel 7 significantly better, so that there is a considerably smaller risk that any pieces of luggage 2 present outside the tunnel 7, or at least the RFID tags 3 thereof, will be detected and read by the RFID antennas 11 , 12, 13 and 16, whilst on the other hand there is a greater chance that the RFID tags 3 associated with a piece of luggage 2 present inside the tunnel 7 will be detected and read. It is further noted as an aside that, as the skilled person knows, the presence of the pieces of luggage 2 can be detected by sensors (not shown), so that the RFID antennas 11 , 12, 13 and 16 can be activated at a suitable point in time, viz. when a piece of luggage 2 is present inside the tunnel 7.

Figures 3 and 4 relate to a second embodiment of a device 21 according to the present invention. The device 21 comprises a double belt conveyor 22 as known per se to those skilled in the art, comprising parallel conveyor belts 23, 24. The conveyor belts 23, 24, or at least the load-bearing part thereof, support a luggage tray 29 supporting a piece of luggage 2, as in the device 1 shown in figure 1. The device 21 further comprises a tunnel 25, whose walls 26, 27, 28 are configured similarly to the walls 8, 9, 10 of the device 1 shown in figure 1. Between the conveyor belts 23, 24, the tunnel 25 further comprises a bottom plate 29, which, like the walls 26, 27, 28, may be considered to be divided into three zones, the middle zone of which extends horizontally, whilst the zones located at the respective ends of the tunnel exhibit a rectilinear taper towards the associated ends of the tunnel 25. The bottom plate 29 thus has an at least substantially concave shape, at least seen in a vertical plane parallel to the conveying direction of the conveyor 22. A flat RFID antenna 30 is provided at the location of the central zone of the bottom plate 29 for reading an RFID tag 3 associated with a piece of luggage 2.

Figure 5 shows a tunnel 41 that forms part of a third preferred embodiment of a device 42, which is schematically shown in top plan view and a side view in figures 6a and 6b. Both the side walls 43, 44 and the upper wall 45 have a curved shape, seen in the conveying direction 46 of the conveyor 47, by means of which an effect comparable to that of the tunnel 7 or the tunnel 25 can be realised, viz. that radio waves emitted by one or a number of RFID antennas (not shown) remain confined within the interior of the tunnel 41.

A similar advantage is realised when using the tunnel 51 shown in figure 7, which forms part of a device 52 according to a fourth preferred embodiment of the invention, which device 52 is schematically shown in top plan view and side view in figures 8a and 8b, including the associated conveyor 53. Seen in the conveying direction 54, the tunnel 51 may be considered to be made up of five successive zones I₁ II, III, IV and V (see figures 8a and 8b). The central zone III has a constant cross-section, seen in the conveying direction, whilst the zones II, IV and I, V are tapered towards the associated end of the tunnel 51 , zones I, V exhibiting a more pronounced taper than zones II, IV. It is further noted that the height and the width of the zones II, IV are smaller than or at most equal to the height and the width of the zone III. The zones II, IV on the one hand and the zone III on the other hand join each other via a vertical wall parts 55, which further contributes positively towards confining radio signals within the interior of the tunnel 51. Although the invention has been explained on the basis of the identification of pieces of luggage in the foregoing, it will be appreciated that it will also be possible to identify other types of products, such as parcels in distribution centres, by means of the invention.

Subfigures (1)-(6) of figure 9a and figure 9b, respectively, relate to the electromagnetic field generated in the central zone (zone Il in figure 2b; zone III in figure 8a) of the tunnel (7, 25, 41 , 51) by the bottom antenna and the side antennas (11 ; 12), respectively. More specifically, said subfigures (1)-(6) show the electromagnetic field in the tunnel at specific distances from the centre in the direction of the two ends (zones I and III in figure 2a; zones l-ll and IV-V in figure 8a).

Subfigure (1) corresponds to the symmetric centre plane of the tunnel, whilst subfigure (6) corresponds to the plane of the tunnel ends.

The specific tapered configuration of the tunnel walls in the direction of the ends of the tunnel impedes the outward flow (or propagation) of the electromagnetic microwave radiation generated within the tunnel, in such a manner that no radio waves are detected outside the tunnel. This prevents RFID tags attached to pieces of luggage present outside the tunnel from being activated by said radio waves and emitting the RFID information stored thereon/therein.

As a result of the use of a tunnel according to the invention comprising such a propagation impeding wall configuration, the RFID antenna disposed inside the tunnel can only read the RFID tag which is present inside the tunnel (and which is activated by the electromagnetic microwave radiation) and identify the piece of luggage associated therewith. In this way an improved baggage handling system exhibiting a higher degree of reliability and accuracy is obtained. It will be understood that the construction of the tunnel and in particular the taper form of the tunnel from the central zone towards the two ends are determining factors in effectively impeding the flow (propagation) of the electromagnetic microwave radiation from the tunnel, such that hardly any electromagnetic microwave radiation is detected outside the tunnel, if at all, and that any such radiation outside the tunnel does not adversely affect the identification of RFID tags.

It has been found by experiment that, when electromagnetic microwave radiation in the frequency range of 860-930 Mhz and the desired modes are used, a tunnel having the dimensions specified below is the most effective in confining the generated electromagnetic microwave radiation within the tunnel (and mainly in the central zone thereof) and impeding an undesirable outflow of said radiation.

More specifically, the width of the central zone ranges between 1200-1300 mm, in particular between 1225-1275 mm, and the height of the central zone ranges between 860-890 mm, in particular between 870-880 mm. It is furthermore preferable if the length of the central zone ranges between 275-375 mm, in particular between 300-350 mm.

As regards the dimensions of the end face of the tapered ends it has been found that the width of the end face of the tapered end preferably ranges between 900-1100 mm, in particular between 1000-1050 mm, and that the height of the end face of the tapered end preferably ranges between 750-850 mm, in particular being 800 mm.

It is furthermore preferable if the length of the tapered end ranges between 225-400 mm, in particular between 250-350 mm.

Claims

1. A device for identifying products, such as pieces of luggage or parcels, provided with an RFID tag, comprising - a conveyor for conveying the products along a conveying path, a tunnel, through the interior of which said conveying path extends, means for generating, in a central zone of the tunnel, electromagnetic microwave radiation reaching outside the tunnel, which generated electromagnetic microwave radiation may have several modes, - at least one RFID antenna inside the tunnel for reading information stored on an RFID tag associated with a product present in the tunnel, characterised in that at least part of at least one wall of the tunnel defining the interior of the tunnel is tapered from the central zone towards at least one end of the tunnel, such that said at least one end of the tunnel prevents the electromagnetic microwave radiation from reaching outside the tunnel.

2. A device according to claim 1 , characterised in that at least part of at least one wall of the tunnel defining the interior of the tunnel is tapered towards two opposite ends of the tunnel.

3. A device according to claim 1 or 2, characterised in that at least two parts of two respective opposite walls of the tunnel defining the interior of the tunnel are tapered towards at least one end of the tunnel.

4. A device according to any one of the preceding claims, characterised in that said at least one RFID antenna is provided on one wall of the tunnel, whilst at least part of the opposite tunnel wall is tapered towards at least one end of the tunnel.

5. A device according to any one of the preceding claims, characterised in that an RFID antenna is provided below the level of a product passing through the tunnel.

6. A device according to any one of the preceding claims, characterised in that the tunnel has a constant cross-section along a part of the length of the tunnel that is spaced from the ends of the tunnel.

7. A device according to any one of the preceding claims, characterised in that said taper is a rectilinear taper.

8. A device according to any one of the preceding claims, characterised in that the cross-sectional area of the central zone of the tunnel and the cross-sectional area of a tapered end of the tunnel are in the proportion of 1.25- 1.45 : 1 , in particular 1.30-1.35 : 1.

9. A device according to any one of the preceding claims, characterised in that, seen in the conveying direction, the length of the central zone of the tunnel and the length of the tapered end of the tunnel are in the proportion of 1.25-1.05 : 1.

10. A device according to any one of the preceding claims, characterised in that the width of the central zone ranges between 1200-1300 mm, in particular between 1225-1275 mm.

11. A device according to any one of the preceding claims, characterised in that the height of the central zone ranges between 860-890 mm, in particular between 870-880 mm.

12. A device according to any one of the preceding claims, characterised in that the length of the central zone ranges between 275-375 mm, in particular between 300-350 mm.

13. A device according to any one of the preceding claims, characterised in that the width of the end face of the tapered end ranges between 900-1100 mm, in particular between 1000-1050 mm.

14. A device according to any one of the preceding claims, characterised in that the height of the end face of the tapered end ranges between 750-850 mm, in particular being 800 mm.

15. A device according to any one of the preceding claims, characterised in that the length of the tapered end ranges between 225-400 mm, in particular between 250-350 mm.