Abstract:
An RFID conveyor system comprises one or more wedges designed to allow an RFID scanner to detect and uniquely identify RFID-tagged baggage as they are conveyed through an antenna array. The RFID conveyor system can also be designed to prevent the reading of previous or subsequent bags by using antennas with highly focused RF read fields in conjunction with RF energy absorbing materials, such as RF curtains, designed to eliminate the identification of any baggage located outside of the “read” area.

Description:
BACKGROUND 
   1. Field of the Invention 
   The field of the invention relates generally to Radio Frequency Identification (RFID) systems and more particularly to systems and methods for implementing an RFID conveyor systems. 
   2. Background Information 
   The aviation industry is experiencing an increased need for advanced security screening and tracking of airline passenger baggage. One of the security procedures that the aviation industry has sought to implement is known as positive passenger-to-baggage matching (PPBM), in which passengers are matched with their checked baggage prior to flight departure. If the passenger does not board the flight, for example, their luggage will be off-loaded from the airplane. This procedure provides greater customer service as well as security. 
   Currently-used barcode tracking systems are limited in their capabilities and efficiency, and greater reliability and robustness than is currently in place is required. For example, in order for a barcode tag on a baggage item to be read, the baggage item or barcode scanner must be manually positioned such that the scanner is facing, and in very close proximity to, the bar code tag. This can make the identification and tracking of baggage a laborious and time-consuming process. As a result, airports need to implement cost-effective, easy-to-install technology that provides fast and accurate baggage sorting and security. Given the millions of baggage items that pass through airports on a daily basis, it is desirable to have a system in which baggage items are electronically identified automatically, regardless of their orientation on the conveyor belt. Of particular interest is a technology that can be integrated with existing baggage reconciliation systems. 
   SUMMARY OF THE INVENTION 
   An RFID conveyor system comprises one or more wedges designed to allow an RFID scanner to detect and uniquely identify RFID-tagged baggage as they are conveyed through an antenna array. The RFID conveyor system can also be designed to prevent the reading of previous or subsequent bags by using antennas with highly focused RF read fields in conjunction with RF energy absorbing materials, such as RF curtains, designed to eliminate the identification of any baggage located outside of the “read” area. 
   These and other features, aspects, and embodiments of the invention are described below in the section entitled “Detailed Description of the Preferred Embodiments.” 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Features, aspects, and embodiments of the inventions are described in conjunction with the attached drawings, in which: 
       FIG. 1  is a diagram illustrating an example RFID conveyor system configured in accordance with one embodiment; 
       FIG. 2  is a flow chart illustrating an example method for tracking baggage items using the RFID conveyor system of  FIG. 1  in accordance with one embodiment; 
       FIG. 3  is a side view of the belt wedge in accordance with one embodiment; 
       FIG. 4  is a top view of the belt wedge in accordance with one embodiment; 
       FIG. 5  is a diagram illustrating an exemplary RFID scanner that can be used in the RFID conveyor systems illustrated in  FIGS. 1 and 2 ; and 
       FIG. 6  is a diagram illustrating an RFID scanner that includes a control computer  602  and that can be used in the RFID conveyor systems illustrated in  FIGS. 1 and 2 . 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1  is a diagram illustrating an RFID conveyor system  100  configured in accordance with one embodiment of the systems and methods described herein. RFID system  100  can be implemented, for example, through modification of an existing airport Baggage Reconciliation System (BRS). In RFID conveyor system  100 , RFID-tagged baggage items  102  are moved along a conveyor belt  108  and passed through an array of RFID antennas  104 . Each baggage item  102  can have attached thereto a baggage tag  114  comprising an RFID tag  116 . For example, an RFID tag  116  can be inserted into, or attached to the surface of, baggage tag  114 . In one embodiments, baggage tag  114  can be a standard International Air Transport Association (IATA) baggage tag. 
   RFID antennas  104  can be mounted in a mounting structure  120  and can be interfaced with one or more RFID scanners. For example, in the embodiment of  FIG. 1 , each RFID antenna  104  is interfaced with a RFID scanner  106 ; however, depending on the embodiment, a single RFID scanner  106  can be interfaced with each RFID antenna  104 . Moreover, more than four RFID antennas  104 , interfaced with one or more RFID scanners  106 , can be included in a RFID conveyor system  100  depending on the requirements of a particular implementation. 
   RF absorbing curtain  122  can also be mounted on mounting fame  120 . As explained below, RF absorbing curtain  122  can be used to ensure accurate reading of RFID tags  116  and to prevent interference by RFID conveyor system  100  with other, surrounding systems. 
   RFID antennas  104  can be configured to operate within a specific frequency range. For example, in one embodiment, RFID antennas  104  can be configured to operate using ultra high frequency (UHF), e.g., 902–928 MHz, spread spectrum technology. Thus, in one example embodiment, RFID tags  116  can be configured to operate at approximately 915 MHz. RFID tags  116  can be dual dipole read-only RFID tags that contain a unique serial number, e.g., a unique 64-bit serial number. The serial number, or other information store on RFID tag  116 , can be used to track baggage items  102  and to associate them with a passenger. 
   Mounting frame  120  can be configured to provide structural support for RFID scanner  106  and RFID antennas  104 . In one embodiment, RFID antennas  104 , and RFID scanners  106  depending on the implementation, are disposed above, below, and on the sides of conveyor belt  108 . Mounting frame  120  can also be configured to act as an RF shield to keep spurious emissions from propagating into surrounding areas and causing false reads or interference with other radio systems operating in the area. Additionally, RF absorbing curtain  122  can be mounted on mounting structure  120  to prevent spurious emissions and false reads of baggage items  102  that have not entered the read zone yet. RFID antennas  104  can also be configured to have highly focused RF read fields in order to avoid interference and the reading of baggage items  102  outside of mounting structure  120 . 
   Thus, RFID conveyor system  100  can be used to track baggage items  102  as required by a particular implementation.  FIG. 2  is a flow chart illustrating an example method for tracking baggage items  102  using, e.g., RFID conveyor system  100  in accordance with the systems and methods described herein. First, in step  202 , a baggage item  102  is placed on conveyor belt  108 . Conveyor belt  108  moves baggage item  102  toward mounting structure  120  and the associate RFID antennas  104 . Antennas  104  can then be activated, in step  206 , once baggage item  102  enters the read zone associated with RFID antennas  104 , in step  204 . For example, RFID antennas  104  can be activated by devices that detect the presence of baggage items  102  as they enter the read zone. Any of a plurality of detector device types can be used. For example, optical detectors, e.g., photo eyes (not shown), can be used to determine the exact positioning of baggage items  102  as they travel along conveyor belt  108 . 
   Once RFID antennas  104  are activated in step  206 , they can be used to allow RFID scanners  106  to read the identification, or other necessary information, from RFID tag  116  associated with baggage item  102  in step  208 . The identification can then be correlated with a specific passenger, for example, in step  210 . If the identification cannot be correlated with a passenger, in step  210 , then a warning message can be generated causing baggage item  102  to be removed, in step  214 , and possibly inspected. 
   As illustrated in  FIG. 1 , RFID scanner, or scanners,  104  can be interfaced with a control computer  160 . Control computer  160  can, for example, be configured to control RFID scanners  106 , to select the appropriate RFID antenna  104 , and to set the appropriate power level. Thus, when an RFID tag  116  has been identified by an RFID scanner  106 , the data read from RFID tag  116  can be transmitted to control computer  160 . Control computer  160  can be configured to format the tag data as required and, depending on the embodiment, transmit the tag data to a host computer system  180 . For example, the host computer system  180  can comprise part of an existing BRS system. The transmission of tag data from control computer  160  to host computer system  180  can occur via a variety of connectivity options, e.g. RS-232, wireless LAN/WAN, USB, or 10BaseT Ethernet, to name just a few. The tag data can then be used to correlate a baggage item  102  with a specific passenger in step  210 . 
   The interface between an RFID scanner  106  and control computer  160  can similarly comprise one of many possible interface options. Alternatively, control computer  160  can be integrated into one or more RFID scanners  106 . In another embodiment, control computer  160 , or the functions performed thereby, can be integrated into host computer system  180 . 
   In one implementation, control computer  160  can be configured to constantly monitor the length, spacing, and location of baggage items  102  as they travel along conveyor belt  108 . For example, in one embodiment, one or more photo eyes and/or line speed controllers can be interfaced with control computer  160 . In order to reduce the incidence of error in RFID conveyor system  100 , a minimum baggage-to-baggage spacing, e.g. 18 inches, can be imposed for baggage items  102  entering mounting structure  120 . If two or more baggage items  102  are allowed to enter mounting structure  120  with less than the desired minimum baggage-to-baggage spacing control computer  160  can prevent the baggage items  102  from being read, in step  212 , and can cause them to be removed from conveyor belt  108  in step  214 . 
   For example, in one implementation, control computer  160  can be configured to communicate with host computer system  180  and send a “too close” message (step  212 ) that causes host computer system  180  to stop conveyor belt  108  and provide an indication of which baggage items  102  need to be removed (step  214 ). Following such an occurrence, control computer  160  can be configured to log the event with a time stamp and store the time stamp along with the identifier read from the RFID tag  116  associated with each removed baggage item  102 . 
   The speed of conveyor belt  108  can be monitored by a shaft-mounted line speed controller. In one embodiment, RFID conveyor system  100  can operate with conveyor belt speeds of greater than 240 feet per minute. Using the line speed controller in conjunction with, e.g., a baggage presence photo eyes, the exact position of each baggage item  102  can be known during the operation of RFID conveyor system  100 , for example, within an accuracy of 0.5 inches. 
   Most airports, for example, have baggage conveyor systems with metallic conveyor sections that can disrupt the reading of RFID tags that are in close proximity to the metal. As a result, the implementation of RFID conveyor system  100  requires that an airport baggage conveyor system with metallic conveyor sections be retrofitted in some manner to ensure that all RFID tags  116  are read regardless of their orientation in relation to the metallic sections comprising the conveyor system. In one embodiment, the metallic sections within the read zone can be replaced by non-metallic conveyor section. This is often only practical for new conveyor systems. Thus, in another embodiment, wedges are used to retrofit existing metallic conveyor systems. 
     FIG. 3  is a diagram illustrating an example wedge  302  that can be used to retrofit an existing conveyor belt system in accordance with the systems and methods described herein. It will also be understood that a new conveyor belt system can also be manufactured to include wedges, such as wedge  302 . Wedge  302  can be positioned between conveyor belt  108  and the metal conveyor sections on the sides and/or underneath conveyor belt  108 . As conveyor belt  108  travels over, or past, a wedge  302 , wedge  302  will push conveyor belt  108  away from the metallic conveyor sections. As described above, the identification or reading of RFID tags  116  can be disrupted when a RFID tag  116  is in close proximity to a metallic conveyor section. If a baggage tag  102 , and associated RFID tag  116 , is near the metallic conveyor section, then it too will be pushed away from the metallic conveyor section allowing the RFID tag to be read without interference from the metallic conveyor section. 
   As can be seen in  FIG. 3 , wedge  302  can comprise a void  304  in which RFID antennas  104  can be installed. Depending on the embodiment, the associated RFID scanner(s)  106  can also be installed within void  304 .  FIG. 4  is a diagram illustrating a bottom view of wedge  302 . 
   Exemplary dimension for wedge  302  are illustrated in  FIGS. 3 and 4 ; however, it will be understood that the dimensions can vary as required by a particular implementation. For example, the dimensions can vary depending on the size and number of RFID antennas installed in void  304  and whether the associated RFID scanners  106  are also installed in void  106 . Moreover, the dimensions associate with conveyor belt  108 , mounting structure  120 , etc., can also impact the dimensions of wedge  302 . 
     FIG. 5  is a diagram illustrating an exemplary RFID system  500  that illustrates an exemplary RFID scanner  502  communicates with one or more RFID tags  510 .  FIG. 5  is present to illustrate how RFID scanners  106 , and associated RFID antennas  104 , can be used to read RFID tags  116 , e.g., in system  100 . In system  500 , data can be exchanged between scanner  502  and RFID tag  510  via radio transmit signal  508  and radio receive signal  512 . RFID scanner  502  comprises RF transceiver  504 , which contains transmitter and receiver electronics, and antenna  506 , which are configured to generate and receive radio transit signal  508  and radio receive signal  512 , respectively. Exchange of data can be accomplished via electromagnetic or electrostatic coupling in the RF spectrum in combination with various modulation and encoding schemes. RFID tag  510  is a transponder that can be attached to an object of interest and act as an information storage mechanism. In many applications, the use of passive RFID tags is desirable, because they have a virtually unlimited operational lifetime and can be smaller, lighter, and cheaper than active RFID tags that contain an internal power source, e.g. battery. Passive RFID tags power themselves by rectifying the RF signal emitted by the RF scanner. Consequently, the range of transmit signal  508  determines the operational range of RFID tag  510 . 
   RF transceiver  504  transmits RF signals to RFID tag  510 , and receives RF signals from RFID tag  510 , via antenna  506 . The data in transmit signal  508  and receive signal  512  can be contained in one or more bits for the purpose of providing identification and other information relevant to the particular RFID tag application. When RFID tag  510  passes within the range of the radio frequency magnetic field emitted by antenna  506 , RFID tag  510  is excited and transmits data back to RFID scanner  502 . A change in the impedance of RFID tag  510  can be used to signal the data to RFID scanner  502  via receive signal  512 . The impedance change in RFID tag  510  can be caused by producing a short circuit across the tag&#39;s antenna connections (not shown) in bursts of very short duration. RF transceiver  504  senses the impedance change as a change in the level of reflected or backscattered energy arriving at antenna  506 . 
   Digital electronics  514 , which can comprise a microprocessor with RAM, performs decoding and reading of receive signal  512 . Similarly, digital electronics  514  performs the coding of transmit signal  508 . Thus, RFID scanner  502  facilitates the reading or writing of data to RFID tags, e.g. RFID tag  510 , that are within range of the RF field emitted by antenna  504 . Together, RF transceiver  504  and digital electronics  514  comprise RFID scanner  502 . Finally, digital electronics  514  can be interfaced with an integral display and/or provide a parallel or serial communications interface to a host computer or industrial controller, e.g. host computer  516 . Alternatively, host computer  516  can be integrated into RFID scanner  502 . 
     FIG. 6  is a diagram illustrating an RFID scanner  600  that includes a control computer  602 . Thus, for example, the RFID scanner functionality provided by scanner  502  can be included in RFID scanner  600  along with control computer  602 . A network interface  604  can also be included in RFID scanner  600 , e.g., to interface RFID scanner with a host computer  180 . As mentioned above, network interface  604  can comprise a RS-232, wireless LAN/WAN, USB, or 10 BaseT Ethernet, to name just a few, interface. 
   RFID scanner  600  can also include Input/Output (I/O)  606 , which can be configured to interface control computer  602  with a variety of devices  608 . For example, devices  608  can comprise devices  610  configured to detect the position of an item on conveyor belt  108 . Such detectors  610  can include, for example, optical detectors. Devices  608  can also include lien speed controllers  612 , and alarms  614 . 
   In one embodiment, RFID scanner  600  comprises stackable PC-104 circuit cards in order to keep the overall size of RFID scanner  600  relatively small. The circuits and components illustrated in  FIG. 6  can be installed on one or more PC- 104  circuit cards. 
   While certain embodiments of the inventions have been described above, it will be understood that the embodiments described are by way of example only. Accordingly, the inventions should not be limited based on the described embodiments. For example, while embodiments involving an RFID conveyor system used for tracking baggage items, an RFID conveyor system configured in accordance with the systems and methods described herein can be used to track any type of item. Thus, the scope of the inventions described herein should only be limited in light of the claims that follow when taken in conjunction with the above description and accompanying drawings.