Abstract:
Identification tags ( 22 ) are secured to objects ( 20 ) moving upon a transport band ( 16 ). The identification tags ( 22 ) each contain a transponder circuit ( 32 ) in electrical communication with transponder antennae ( 30, 31 ). The transponder circuit ( 32 ) contains a unique digital code containing data relating to the object ( 20 ). When the identification tag ( 22 ) is located beneath the object ( 20 ), at least one reader antenna ( 25 ) is positioned beneath the transport band ( 16 ) and in alignment with a selected aperture ( 34 ) extending through a support plate ( 12 ). One or more apertures ( 34 ) in alignment with the reader antenna ( 25 ) provide capacitive coupling between the transponder antennae ( 30, 31 ) and the reader antenna ( 25 ). The reader circuit ( 28 ) generates a signal in the presence of an identification tag ( 22 ), which is transmitted to the transponder antenna ( 30 ) located on the identification tag ( 22 ). The signal energizes the transponder circuit ( 32 ), which sends a transponder signal via the transponder antenna ( 30 ) back to the reader antenna ( 25 ). The reader circuit ( 28 ) demodulates the transponder signal to identify the data.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This is a continuation-in-part of a pending commonly-assigned prior application by Noel H. Eberhardt et al. titled “Conveyor Bed with Openings for Capacitive Coupled Readers,” application Ser. No. 09/225,760, filed Jan. 5, 1999, now U.S. Pat No. 6,107,921, the disclosure of which prior application is hereby incorporated by reference, verbatim and with the same effect as though it were fully and completely set forth herein. 
    
    
     TECHNICAL FIELD 
     This invention relates to the identification of objects placed upon a transport device, wherein the objects have identification tags. The transport device has openings which enable scanning of identification tags by capacitive coupled readers located beneath the object on the transport device. 
     BACKGROUND OF THE INVENTION 
     Automatic transport devices often transport a plurality of goods in objects which must be individually identified to be properly sorted. Parcels, such as airline baggage, shipping containers, production inventory, machine parts, and component parts, are often identified with flexible tags or labels. Electromagnetic sensing is sometimes used to identify the flexible tags or labels on individual objects placed upon a conveyor. When the objects are oriented so that the identification tags are located beneath the object on a conveyor, they cannot be read by conventional line of sight reading equipment located above the conveyor. 
     U.S. Pat. No. 5,450,492 issuing to Hook et al. on Sep. 12, 1995 is representative of an electronic identification system having a transmitter for generating an electromagnetic excitation signal, and one or more transponder s with variable time and frequency. 
     U.S. Pat. No. 4,724,953 issuing to Winchester on Feb. 16, 1988 discloses a food conveyor apparatus having a plurality of rows of oblong holes positioned along the length of the conveyor, with each row offset from adjacent rows of holes. The platform supports an endless mesh conveyor band. The plurality of holes and the endless mesh conveyor band allow food debris to fall through the conveyor band and platform to simplify cleaning in a food processing environment. 
     U.S. Pat. No. 5,040,549 issuing to Ray on Aug. 20, 1991 discloses a band conveyor for feeding tobacco into a cutting machine. A plate supporting the conveyor band has a plurality of apertures through which debris may fall or be swept, and a means below the plate to collect the particulate material. 
     To be effective, the identification tags on individual objects must be oriented to position the identification tags in relation to the reader antenna positioned in proximity to the conveyor band. Manual orientation of the objects to orient the identification tags in relation to reader antenna is labor intensive and time consuming. Where the identification tag is positioned beneath the object, it cannot easily be read by reader antenna positioned above the conveyor. Thus, what is needed is a way to position the reader antenna beneath the conveyor band to read identification tags located beneath the object. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     A preferred embodiment of the present invention will now be described with reference to the accompanying drawings, in which: 
     FIG. 1 is a perspective view of a plurality of objects located upon a transport device, with some identification tags located beneath the object. 
     FIG. 2 is a cross sectional view of the transport device taken along lines  2 — 2  in FIG. 1, showing reader antenna positioned lower than a support plate and in alignment with suitable apertures located in the support plate. 
     FIG. 3 is a partial top view of the support plate having a zigzag aperture positioned to isolate first and second support plate sides, with an object positioned above the support plate. 
     FIG. 4A is a partial top view of the support plate having a plurality of apertures extending through the support plate with a plurality of reader antennae positioned in the apertures, and several transponder circuits shown in various orientations upon a transport band. 
     FIG. 4B is a schematic view of the support plate and reader circuit shown in FIG.  4 A. 
     FIG. 5 is a partial view of a plurality of conductive rollers positioned in spaced relation between opposing sides of a frame, and wherein reader antenna are positioned in the space provided between adjacent rollers. 
     FIG. 6A is a partial view of a plurality of conductive rollers positioned in side by side relation, wherein adjacent rollers are of opposite polarity. 
     FIG. 6B is a schematic view of the conductive rollers shown in FIG.  6 A. 
     FIG. 7A is a schematic view of the reader circuit and transponder circuit, wherein the reader circuit and first transponder antenna are each coupled to ground. 
     FIG. 7B is a partial view of the support plate with an object positioned above the support plate. 
     FIG. 7C is a schematic view of the reader circuit with first and second reader antenna and the transponder circuit with first and second transponder antenna. 
     FIG. 8 is a partial view of the support plate, wherein the transponder antenna is positioned in non-parallel alignment with the reader antenna. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     As shown in FIGS. 1 and 2, an object  20  (e.g., a parcel) having an identification tag  22  (e.g., a transponder, RFID label, etc.) secured thereon, is moved along a transport device  10  (e.g., a conveyor). The identification tag  22  contains a transponder circuit comprising at least one transponder antenna  30 . In the preferred embodiment, the transponder circuit  32  comprises a first and a second transponder antennae  30 ,  31 . The transponder circuit  32  is in electrical communication with the first and second transponder antennae  30 ,  31 . The transponder circuit  32  contains a unique digital code which contains information/data relating to a specific object, such as the identification, contents, destination, disposition, ownership, history and/or inventory data of the specific object. 
     The transport device  10  comprises a support plate  12  secured to a frame  14 , the support plate  12  having an aperture and/or a separation  34  therein. As shown in FIG. 3, the support plate  12  is made of a first support plate side  42  and a second support plate side  44 . The first support plate side  42  is positioned in spaced relation to the second support plate side  44 . The first and second support plate sides  42 ,  44  may each be made of a conductive material, such as steel. Preferably, a pattern of conductive material, however, is secured to a non-conductive support plate, and the pattern of conductive material is connected to respective polarity generated by a reader circuit  28 . 
     A support plate aperture and/or separation  34  extend in a continuous path between first and second support plate sides  42 ,  44 , electrically isolating first support plate side  42  from second support plate side  44 . Preferably, the support plate aperture/separation  34  extends in a zigzag or semi-zigzag path substantially across the width of the support plate  12 , isolating the first support plate side  42  from the second support plate side  44 . Alternately, a plurality of offset apertures/separation  34  may be provided, as shown in FIGS. 4A and 4B, and first and second support plate sides  42 ,  44  may be of opposing polarity. 
     Referring back to FIGS. 1 and 2, a transport band  16  advances along the support plate  12  to move randomly oriented objects  20 . The transport band  16  is powered by a suitable drive means  18 , such as a motor, band or shaft, to advance the transport band  16  over the conductive support plate  12  and along the frame  14 . The transport band  16  is preferably made of a non-conductive material, such as plastic, fiberglass, rubber, to enable a signal to pass through the transport band  16 . 
     Alternatively, as shown in FIG. 5, a plurality of conductive rollers  40 ,  41  may extend in spaced relation between opposing sides of the support plate  12 . At least one reader antenna  25  is positioned in the space between the rollers  40 ,  41 . The reader circuit  28  may provide one polarity to the conductive rollers  40 ,  41  and an opposite polarity to at least one reader antenna  25 . The rollers  40 ,  41  may be driven by a chain, band, motor or other suitable drive means  18  to move the objects  20  along the transport band  16  in a manner well known in the art. Alternatively, one or more rollers  40 ,  41  may be inclined to rotate in the presence of the object  20  by the force of gravity as the object  20  moves along the transport band  16  in a manner well known in the art. 
     As shown in FIGS. 6A and 6B, the plurality of rollers  46 ,  48  may be placed in a row in a side-by-side relation between opposing sides of the frame  14 . The plurality of rollers  46 ,  48  in each row may be placed in alternating polarity alignment, with rollers  46  of opposite polarity to rollers  48 . Adjacent rows of rollers  46 ,  48  are positioned in staggered alignment, so that rollers  46  of a given polarity in one row are aligned with rollers  48  of an opposite polarity in an adjacent row. Transponder antennae  30 ,  31  located in identification tag  22  on the object  20  will cross over rollers  46 ,  48  of opposing polarity, regardless of the orientation of the object  20  on the transport band  16 . 
     A reader circuit  28  (which may comprise an encoder or programmer) located in proximity to the transport device  10  is in electrical communication with at least one reader antenna  25 . For example, if one reader antenna  25  is in electrical communication with the reader circuit  28 , common ground coupling is used between the first transponder antenna  30  and the support plate  12  and the reader circuit  28  is coupled to ground as illustrated in FIGS. 7A and 7B, eliminating the need for the first reader antenna  25 . As a result, the reader antenna  25  capacitively (electrostatically) couples to at least one transponder antenna  30  to transmit and receive signals. 
     A further alternative example is when the reader circuit  28  is electrically coupled to two reader antennae  25 ,  26  as illustrated in FIG. 7C, wherein a first reader antenna  25  could be coupled to ground (e.g., via the support plate  12  or the frame  14 ) and a second reader antenna  26  is capacitively coupled to at least one transponder antenna  30  and/or  31  to transmit and receive signals. Alternatively, the first and second reader antennae  25 ,  26  could both be capacitively coupled to at least one transponder antenna  30  and/or  31 . 
     Yet a further example is when the reader circuit  28  is electrically coupled to three reader antennae  25 ,  26 ,  27 , wherein a first reader antenna  25  is capacitively coupled to at least one transponder antenna  30  and/or  31  to transmit signals, a second reader antenna  26  is capacitively coupled to at least one transponder antenna  30  and/or  31  to receive signals and a third reader antenna  27  is coupled to ground (e.g., via the support plate  12  or the frame  14 ). 
     In the preferred embodiment, the reader circuit  28  is electrically coupled to two reader antennae  25 ,  26  wherein the reader circuit  28  is coupled to ground, a first reader antenna  25  is capacitively coupled to at least one transponder antenna  30  and/or  31  to transmit signals and a second reader antenna  26  is capacitively coupled to at least one transponder antenna  30  and/or  31  to receive signals. For ease of understanding and explanation, the following description adopts the reader configuration of the preferred embodiment. 
     Preferably, the identification tags  22  are placed upon a side of each object  20  prior to placing the object  20  upon the transport band  16 . The objects  20  may be of random size and shape. As the objects  20  are randomly positioned upon the transport band  16 , the identification tags  22  may be located anywhere on the object  20 . When the identification tag  22  is disposed on a side of the object  20  that is in contact with the transport band  16 , line of sight reading equipment usually located above the transport band  16  cannot read the identification tag  22 . In order to ensure that each object  20  is properly identified as it passes along the transport band  16 , in addition to line of sight reading equipment positioned above the transport band  16 , at least the first and second reader antennae  25 ,  26  are positioned below the support plate  12  and in proximity or alignment with apertures or separations  34  located in the support plate  12 . The apertures  34  in the support plate  12  provide for passage of a signal between the first and second reader antennae  25 ,  26  and the transponder antennae  30 ,  31  located in the identification tag  22 . Thus, if the identification tag  22  is located on the bottom of the object  20 , it is read by a reader antenna  25  positioned lower than the support plate  12 . 
     FIG. 8 illustrates the first and second transponder antennae  30 ,  31  located in the identification tag  22  positioned in a non-parallel alignment to the aperture/separation  34 . The transponder antennae  30 ,  31  may be either horizontally or vertically oriented, or a variation of both, with respect to the support plate  12 . Referring back to FIG. 4A, several identification tags  22  are positioned in random orientation upon the transport band  16 . A plurality of side by side apertures  38 A through  38 E each have a respective pair of reader antennae  25 A through  25 E positioned therein. Identification tag  22 A couples to reader antennae  25 A and  25 B. Identification tag  22 B couples to reader antennae  25 A and  25 D. Identification tag  22 C couples to reader antennae  25 B and  25 C. Identification tag  22 D couples to reader antennae  25 C and  25 E. Thus, as the object moves along the transport band, at least one reader antenna  25  couples to one of the transponder antennae  30 ,  31 . 
     In operation, a reader circuit  28  is in electrical communication with the first reader antenna  25  and second reader antenna  26 , both of which are positioned lower than the support plate  12  and in proximity to an aperture/separation  34 . The reader circuit  28  generates an excitation signal which is electrically coupled to the first reader antenna  25 . Preferably, as the object  20  passes over the aperture  34 , the first transponder antenna  30  couples to ground (e.g., via the support plate  12 ) and the second transponder antenna  31  couples to the first reader antenna  25 . The first reader antenna  25  capacitively couples the excitation signal, which may include commands from the reader circuit  28 , to the identification tag  22 , thereby activating the transponder circuit  32 . The excitation signal serves as a power source and a clock source for the transponder circuit  32 . The identification tag  22  generates and capacitively couples a transponder signal to the reader circuit  28  via the transponder antennae  30 ,  31  and the second reader antenna  26 . The transponder signal is received by the second reader antenna  26  as the object  20  traverses across the support plate aperture  34  located between the first support plate side  42  and the second support plate side  44 . The second reader antenna  26  electrically couples the transponder signal to the reader circuit  28  where the transponder signal is demodulated to identify the data in the transponder signal, such as the ownership, contents, history, destination, and/or disposition of the object. 
     While the invention has been described in conjunction with a specific embodiment thereof, additional advantages and modifications will readily occur to those skilled in the art. The invention, in its broader aspects, is therefore not limited to the specific details, representative apparatus, and illustrative examples shown and described. Various alterations, modifications and variations will be apparent to those skilled in the art in light of the foregoing description. Thus, it should be understood that the invention is not limited by the foregoing description, but embraces all such alterations, modifications and variations in accordance with the spirit and scope of the appended claims.