RFID Reader

Abstract

An RFID reader system (100) for determining the location of electronically tagged items within a container having multiple container sections includes an RF antenna array (102) and an RFID reader (104). The RF antenna array (102) includes an arrangement of overlapping antenna coils (108) that form continuous read zones (730) that are individually associated with the container sections (210) of the container (200). The RFID reader (104) includes an antenna controller (106) that individually activates each of the antenna coils, and a processor (110). The processor (110) receives a plurality of response signals associated with combinations of activated antenna coils from the RF antenna array, identifies read zones responsive to the activated antenna coil combinations, and identifies the container sections as the locations of electronically tagged items based on the identified read zones.

Description

[Technical field]

[0001] The present disclosure relates generally to determining the location of radio frequency identification (RFID) tags, and more particularly to systems and antenna arrangements for determining the location of RFID tagged items and methods for determining the location of RFID tagged items. [Background technology]

[0002] Radio frequency identification (RFID) is a method of radio frequency identification, where data is stored electronically on a tag and is readable by an RFID reader to identify, locate and / or track the tagged item. RFID systems are not necessarily configured to provide the exact location of a tagged item. Instead, they often provide a general location of the tagged item. For example, if a tagged item is located in a cabinet, an RFID reader is often configured to verify the presence of the tag in the cabinet. In this case, it is not necessarily possible to verify which shelf or which drawer within the cabinet the tagged item is located on.

[0003] RFID readers work by emitting electrical signals and generating electromagnetic fields that interact with the antenna coil of an RFID tag to interrogate the tag and obtain identification information from it. The reading range of an RFID reader depends on the strength of the reading signal. Electromagnetic interference (EMI), sometimes called radio frequency interference (RFI), is a disturbance caused by external sources that affect electrical circuits, for example by electromagnetic induction. Because EMI can degrade the performance of electrical circuits, electromagnetic compatibility (EMC) requirements and standards exist for many different types of electronic equipment to limit electromagnetic emissions from the equipment. This ensures that such equipment, when used as intended, does not interfere with the operation of other electronic equipment within a certain distance. Summary of the Invention [Means for solving the problem]

[0004] Any discussion of documents, acts, materials, devices, articles or the like which has been included in this specification should not be construed as an admission that any or all of such matters formed part of the prior art base or were common general knowledge in the field relevant to this disclosure prior to the priority date of each claim of this application.

[0005] In one aspect, an RFID reader system for determining a location of an electronically tagged item within a container having multiple container sections is provided. The system includes an RF antenna array and an RFID reader. The RF antenna array includes an arrangement of overlapping antenna coils forming continuous read zones individually associated with the container sections of the container. The RFID reader includes an antenna controller that individually activates each of the antenna coils and a processor. The processor receives a plurality of response signals associated with combinations of activated antenna coils from the RF antenna array, identifies read zones responsive to the combinations of activated antenna coils, and identifies the container sections as locations of the electronically tagged items based on the identified read zones.

[0006] The RF antenna array may comprise a first series of coplanar antenna coils and a second series of coplanar antenna coils. Each antenna coil of the first series includes one or more antenna coil loops. The antenna coils of the first series are arranged in an overlapping manner such that their antenna coil loops are aligned along a first axis, thereby generating a first continuous read zone along the first axis having a series of interleaved read zones generated by the antenna coil loops of the first series. Each antenna coil of the second series includes one or more antenna coil loops. The antenna coils of the second series are arranged in an overlapping manner such that their antenna coil loops are aligned along a second axis, thereby generating a second continuous read zone along the second axis having a series of interleaved read zones generated by the antenna coil loops of the second series. The second axis is parallel to and spaced apart from the first axis, such that the first continuous read zone and the second continuous read zone partially overlap to form a third continuous read zone.

[0007] The antenna coil may comprise a first loop arrangement and a second loop arrangement conductively connected to the first loop arrangement. The first loop arrangement includes a first loop having a first current that induces a first magnetic field for detecting an electronic tag in a near field. The second loop arrangement includes a second loop having a second current that rotates oppositely to the first current. The second current induces a second magnetic field for detecting an electronic tag in the near field. The first loop arrangement has a first inner region. The second loop arrangement has a second inner region. The first magnetic field reduces the second magnetic field in the far field.

[0008] The first and second magnetic fields may be oriented in opposite directions and a sum of the first and second magnetic fields may be substantially zero in the far field.The sequence may include a non-even number of antenna loops.

[0009] The sequences may have a figure-of-eight shape with two antenna loops having substantially the same inner area. A first series may include two overlapping figure-of-eight shaped antenna coils and a second series may include two overlapping figure-of-eight shaped antenna coils.

[0010] A first continuous read zone may be associated with the first container section and the second container section, a second continuous read zone may be associated with the second container section and the third container section, and a third continuous read zone may be associated with the second container section.

[0011] The number of loops and the inner area of ​​the loops may cause the sum of the first and second magnetic fields to be substantially zero in the far field.

[0012] Each contiguous read zone may include a series of interleaved read zones generated by an antenna coil.

[0013] The continuous read zone may have a magnetic field direction that detects electronic tags in a given upright orientation.

[0014] The RF antenna array may include a plurality of laterally overlapping series of antenna coils, the series of antenna coils may be aligned along the length of the container section, and the RF antenna array may be disposed across the plurality of sections.

[0015] The antenna controller may activate each of the antenna coils at a plurality of power levels, and the processor may receive a plurality of response signals respectively associated with the plurality of power levels, and determine the height level of the container based on the plurality of received response signals.

[0016] In another aspect, a method is provided for determining a location of an electronically tagged article within a container section of a container using an RFID reader, the method including the steps of individually activating each antenna coil of a set of overlapping antenna coils forming a continuous read zone individually associated with the container section, receiving a plurality of response signals associated with the activated antenna coil combination from the set of antenna coils, identifying a read zone responsive to the activated antenna coil combination, and identifying the container section as the location of the article based on the identified read zone.

[0017] Individually activating each antenna coil may include operating each antenna coil at a plurality of different powers. Receiving a plurality of response signals may include receiving a response signal associated with each antenna coil for each of a plurality of different powers. Identifying the container section may include determining a height level of the container in response to the plurality of response signals.

[0018] In another aspect, an RF antenna coil is provided. The RF antenna coil includes a first loop arrangement including a first loop having a first current that induces a first magnetic field for detecting an electronic tag in a near field, and a second loop arrangement conductively connected to the first loop arrangement. The second loop arrangement includes a second loop having a second current that rotates in an opposite direction to the first current. The second current induces a second magnetic field for detecting an electronic tag in the near field. The first loop arrangement has a first inner region. The second loop arrangement has a second inner region. The first magnetic field reduces the second magnetic field in the far field.

[0019] The first and second magnetic fields may be directed in opposite directions, and the sum of the first and second magnetic fields may be substantially zero in the far field.

[0020] The first loop arrangement and the second loop arrangement may be substantially coplanar.

[0021] The first loop arrangement and the second loop arrangement may form a sequence of spaced apart antenna loops.

[0022] The sequence may have a figure eight shape in which the two antenna loops have substantially the same inner area.

[0023] The sequence may include a non-even number of antenna loops.

[0024] The first loop may be a different size than the second loop, and the first inner region may be substantially the same as the second inner region.

[0025] These and other aspects and features will become apparent to those of ordinary skill in the art upon review of the following description of specific non-limiting embodiments in conjunction with the accompanying drawings.

[0026] The descriptions made herein should be understood as relating to some non-limiting embodiments and are not intended to be a description of the entire invention. If there are any provisions that are deemed to apply to all non-limiting embodiments, the applicant / patent owner reserves the right to subsequently delete them from this specification and will not rely on these descriptions for the acceptance or subsequent grant of a patent in any country. [Brief description of the drawings]

[0027] The detailed description of the illustrative (non-limiting) embodiments will be better understood when considered in conjunction with the accompanying drawings, in which:

[0028] [Figure 1] 1 is a schematic diagram of a non-limiting embodiment of an RFID system.

[0029] [Figure 2A]FIG. 2 illustrates an exemplary, non-limiting embodiment of a cabinet in which the RFID system of FIG. 1 may be used to locate RFID-tagged items within the cabinet.

[0030] [Figure 2B] FIG. 2B is a schematic diagram of a tray within the cabinet of FIG. 2A, the tray holding a plurality of tagged blood bags.

[0031] [Figure 2C] FIG. 1 is a schematic diagram of a blood bag with an RFID tag attached.

[0032] [Figure 2D] 1 is a schematic diagram of an RFID antenna coupling with an RFID tag placed within a magnetic field.

[0033] [Diagram 3] FIG. 1 is a schematic diagram illustrating a prior art antenna configuration.

[0034] [Figure 4A] FIG. 1 is a schematic diagram of a prior art figure-of-eight antenna configuration.

[0035] [Figure 4B] FIG. 2 is a schematic diagram of a multi-loop antenna coil.

[0036] [Figure 4C] FIG. 1 is a schematic diagram of a prior art antenna array.

[0037] [Figure 4D] FIG. 4D illustrates the placement of the antenna array of FIG. 4C relative to a container section in an area.

[0038] [Figure 5A] FIG. 2 is a schematic diagram of a non-limiting embodiment of an antenna coil arrangement.

[0039] [Figure 5B]FIG. 5B illustrates the placement of the antenna coil of FIG. 5A relative to a container section within the region.

[0040] [Figure 5C] FIG. 5B illustrates the arrangement of the two antenna coils of FIG. 5A relative to the two container sections of FIG. 5B.

[0041] [Figure 6A] FIG. 1 illustrates the operation of a figure-of-eight antenna coil according to one non-limiting embodiment.

[0042] [Figure 6B] 11A-11C illustrate the operation of another non-limiting embodiment of an antenna coil.

[0043] [Figure 6C] FIG. 6B is a schematic diagram of the figure-of-eight antenna coil of FIG. 6A applied to a container holding tagged articles.

[0044] [Figure 6D] FIG. 6C is a schematic diagram of the antenna coil of FIG. 6B applied to a container holding tagged articles.

[0045] [Figure 7A] FIG. 2 is a schematic diagram of a first non-limiting embodiment of an antenna arrangement.

[0046] [Figure 7B] FIG. 2 is a schematic diagram of a second non-limiting embodiment of an antenna arrangement.

[0047] [Figure 7C] FIG. 7B illustrates the operation of the first non-limiting embodiment of FIG. 7A.

[0048] [Figure 7D] FIG. 7C illustrates the operation of the second non-limiting embodiment of FIG. 7B.

[0049] [Figure 8A]FIG. 2 is a schematic diagram of another non-limiting embodiment of an antenna arrangement.

[0050] [Figure 8B] FIG. 8B illustrates the operation of the antenna arrangement of FIG. 8A.

[0051] [Figure 8C] FIG. 8B illustrates the operation of the antenna arrangement of FIG. 8A.

[0052] [Figure 9] 1 is a flow diagram of a non-limiting embodiment of a method for determining a position of an item within a container section of a container.

[0053] [Figure 10] FIG. 2 is a schematic diagram of a non-limiting embodiment of a multi-shelf arrangement of antennas.

[0054] In the drawings, like reference numbers indicate like parts.

[0055] The drawings are not necessarily to scale and may be illustrated by phantom lines, perspective views, and fragmentary views. In certain instances, details that are not necessary for an understanding of the non-limiting embodiments or that make other details difficult to perceive may be omitted. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0056] Antenna Systems

[0057] Reference will now be made in detail to various non-limiting embodiments of methods and systems for determining the location of an item in a storage system. Other non-limiting embodiment(s), modifications and equivalents will be apparent to those skilled in the art in view of the non-limiting embodiment(s) disclosed herein, and such variations should be considered to be within the scope of the appended claims.

[0058] Moreover, those skilled in the art will recognize that certain structural and operational details of the non-limiting embodiment(s) described below may be varied or omitted entirely (i.e., are not required). In other instances, well-known methods, procedures, and components have not been described in detail.

[0059] FIG. 1 of the drawings is a schematic diagram of a non-limiting embodiment of a radio frequency identification (RFID) reader system 100 for determining the location of an electronically tagged item within a container having multiple container sections. The RFID reader system 100 has a radio frequency (RF) antenna array 102 in communication with an RFID reader 104. The RF antenna array 102 includes an arrangement of overlapping antenna coils 108 forming continuous read zones 730 individually associated with container sections 210 of a container 200, as described in more detail elsewhere herein, for example with reference to FIGS. 2 and 7. The RFID reader 104 includes an antenna controller 106 that individually activates each antenna coil 108, and a processor 110. The processor 110 receives a plurality of response signals from the RF antenna array 102. The response signals are associated with combinations of activated antenna coils. The processor 110 further identifies read zones responsive to the combinations of activated antenna coils and identifies the container sections as the location of the item based on the identified read zones.

[0060] The reply signal is generated in response to an interrogation signal from the RFID reader 104. The RF antenna array 102 generates contiguous read zones, each contiguous read zone being associated with a container section of the container, as described in more detail elsewhere herein.

[0061] In some non-limiting embodiments, the antenna controller and processor may be provided in one shared processing unit. In addition to the antenna controller 106 and the processor 110, the RFID reader 104 includes various modules 120 that support the operation of the RFID reader 104. These modules may include one or more of a memory 112 (e.g., volatile memory, non-volatile memory, and / or other storage), a communication interface 114 that supports communication between the RFID reader 104 and other devices (e.g., a network interface controller or other form of interface hardware), and a user interface 116. The modules 120 of the RFID reader 104 cooperate with each other by exchanging data via a bus 118.

[0062] 2A of the drawings, an example of a container 202 in which an item 204 may be placed is a trolley or cabinet 200, and the item 204 in this example is a plasma box or blood bag 206 with an electronic tag in the form of an RFID tag 208 affixed thereto. Each blood bag 206 is placed at a cabinet level (e.g., in a drawer or on a shelf 214). Each tagged item is also placed within a container section 210 of the cabinet 200. Each container section 210 is in the form of a container, such as a tray 212. In this non-limiting embodiment, each shelf 214 includes a plurality of trays 212. As shown, the exemplary cabinet 200 includes a plurality of levels in the form of shelves 214 (vertically arranged as labeled by the Y axis), and each shelf 214 includes a plurality of trays 212. In the exemplary non-limiting embodiment, the trays 212 are arranged in a row along the width of the cabinet 200 (horizontally arranged as labeled by the X axis). As shown in FIG. 2B, each tray 212 is elongated and holds a plurality of RFID-tagged blood bags 206 stacked lengthwise of the tray 212 across the depth of the cabinet 200 (as labeled by the Z axis). FIG. 2C shows that each blood bag 206 has an RFID tag 208 with a tag antenna 209. In the illustrated example, the blood bags 206 are stacked in the Z direction. The tag antennas 209 of the RFID tags 208 are substantially in the XY plane. In alternative non-limiting embodiments, the trays may be arranged and / or stacked in a variety of alternative configurations, for example, each shelf may include two parallel rows of trays.

[0063] Each container section 210 of the container 202 is associated with a predefined combination of antenna coils. The processor 110 determines a first location indicator of the article 204 by determining an activated antenna coil combination responsive to a plurality of received response signals. Exemplary, non-limiting embodiments of predetermined antenna coil combinations and logic used to determine the location of a tagged article are described in more detail elsewhere herein.

[0064] FIG. 2D illustrates how the RFID antenna coil 108 couples with the tag antenna 209 of an RFID tag 208 placed within its magnetic field 220 (H). The magnetic field 220 is illustrated with dashed lines, and the magnetic field orientation is shown as curving around the antenna coil 108. In the regions above and below the antenna coil 108, the magnetic field is curved to be approximately parallel to the plane in which the antenna coil 108 lies. The magnetic field orientation in these regions facilitates coupling with the tag antenna 209, which has a more or less perpendicular orientation to the orientation of the reader's antenna coil 108. Thus, in examples where the antenna coil 108 is placed in, on, or below (or otherwise in the same plane as) the floor of a container drawer, tray, or shelf (the XY plane in the example shown in FIG. 2D), the tag 208 is placed upright in the container such that the tag is oriented perpendicular to the floor of the container drawer. A tray or shelf (tag oriented in the YZ plane in the example shown in FIG. 2D, but which may be any plane parallel to the Z axis) can couple with the magnetic field 220 when the tag is placed in the region above or below the reader antenna 108. This region above and / or below the antenna coil is referred to herein as the "read zone." In contrast, if this vertical tag 208 is placed in the central region of the antenna coil 108 where the orientation of the magnetic field 220 is substantially perpendicular to the orientation of the antenna coil 108 (i.e., parallel to the Z axis), the magnetic field will be substantially parallel to the orientation of the tag antenna 209 and coupling will be reduced or even nonexistent. As a result, tagged articles placed in such a more central region or zone will not be located by the RFID reader 104. This central region is therefore considered a "dead zone," i.e., a region where no read region exists for this particular antenna coil.

[0065] In some non-limiting embodiments described herein, the continuous read zone has a magnetic field orientation that detects electronic tags in a predetermined upright orientation that is perpendicular to the orientation of the antenna coil, as described with reference to FIG. 2D.

[0066] Antenna Array

[0067] In some non-limiting embodiments, the antenna coil 108 in the system 100 is positioned to allow for accurate determination of the location of an article. In some non-limiting embodiments, the antenna coil 108 in the system 100 is positioned to reduce radio emissions to reduce far-field EMI, for example to meet EMC requirements. At the same time, the antenna coil 108 is positioned to ensure sufficient field strength and operating range in the near field proximate to the antenna coil 108.

[0068] 3 is a schematic diagram of a prior art antenna configuration 300. In this example, two antenna coils 302 are positioned relative to four trays 304 such that each antenna coil 302 is associated with two of the trays 304. In this configuration, if the first antenna coil 306 provides a signal to the reader indicating the presence of an RFID tag, the RFID tag may be located in either of the first two trays 308, 310 associated with the first antenna coil 306. Similarly, if the second antenna coil 312 provides a signal to the reader indicating the presence of an RFID tag, the RFID tag may be located in either of the two trays 314, 316 associated with the second antenna coil 312. Thus, with this antenna configuration 300, it is not possible to precisely locate an RFID tag in one of the four trays.

[0069] Another drawback of the configuration of Figure 3 is that the maximum power generated by each antenna coil is limited by EMC regulations that stipulate limits on electromagnetic radiation at a certain distance from electronic equipment. One solution is to configure the two antenna coils 302 so that the current in one antenna coil flows in the opposite direction to the current in the other antenna coil, which creates mutually cancelling magnetic fields in the far field. However, if both antenna coils are activated simultaneously, creating such a net-zero far field, it is impossible to distinguish which of the four trays 304 a tagged article is in.

[0070] 4A shows a non-limiting embodiment of an antenna configuration 420 in which an antenna coil 422 is arranged to form a figure-of-eight loop with a first loop 424 and a second loop 426. In this configuration 420, the two loops 424, 426 are arranged as far apart as possible to avoid placing the portions 422 of the antenna coil, such as portions 422a, 422b, adjacent to each other, thereby minimizing near-field cancellation. In this way, this figure-of-eight antenna coil 422 can provide additional conductive portions (e.g., compared to each of the antenna coils 302 of FIG. 3) and can improve the accuracy of the antenna operation.

[0071] The antenna coil 422 includes two loops 424, 426 arranged in a figure-8 shaped antenna structure, with counter-rotating currents in each loop. This has two advantages. First, the loops are far enough apart that the electric field strength and operating range in the near field close to the loops are optimized. Second, the currents in the two loops 424, 426 flow in opposite directions, which cancels the magnetic fields in the far field. This is done to meet global emission regulation (EMC) requirements.

[0072] Depending on the number of antenna coil loops and the internal area of ​​the loops, the sum of the first and second magnetic fields may be reduced or even substantially zero in the far field. Various non-limiting embodiments of such antenna arrays are described herein.

[0073] 4B shows a non-limiting embodiment of a multi-loop antenna coil. A radio frequency (RF) antenna coil 430 has a first loop arrangement 432 including a first loop 432.1 (including two loops 432.1, 432.2 in this example). The loops of the first loop arrangement 432 have a first current 436 that induces a first magnetic field +H for detecting electronic tags in the near field. The antenna coil 430 also has a second loop arrangement 442 conductively connected (at a connection 444) to the first loop arrangement 432. The second loop arrangement 442 includes a second loop 442.1 (including two loops 442.1, 442.2 in this example) that has a second current 446 that rotates in the opposite direction to the first current 436, and the second current 446 induces a second magnetic field -H for detecting electronic tags in the near field. The first loop arrangement 432 has a first inner area A1 and the second loop arrangement has a second inner area A2, where the first magnetic field +H reduces the second magnetic field -H in the far field. The dimension of the first inner area A1 is the sum of the inner areas of the first loops 432.1, 432.2. The dimension of the second inner area A2 is the sum of the inner areas of the second loops 442.1, 442.2.

[0074] For magnetic field strength H, H=B / μ, where B is the magnetic flux density and μ is the permeability of the relevant material (e.g. air). The magnetic flux Φ through a surface is the surface integral of the normal component of the magnetic field B on that surface.

number

[0075] Thus, in some non-limiting embodiments of the dual or multi-loop antenna coils described herein, the first and second magnetic fields are in opposite directions such that the sum of the first and second magnetic fields is substantially zero in the far field. To facilitate this, some non-limiting embodiments have the first and second loop arrangements substantially coplanar.

[0076] In a multi-loop antenna coil, a first loop arrangement includes all loops that contribute to a first magnetic field. A second loop arrangement includes all loops that contribute to a second magnetic field. The first loop arrangement and the second loop arrangement form a sequence of antenna loops. The sequence may include an even or a non-even number of antenna loops.

[0077] In some non-limiting embodiments, the first loop is sized differently relative to the second loop such that the first interior area is substantially the same as the second interior area. However, the loops may be the same size or different sizes, such that the interior areas of the individual loops may be the same or different. Nevertheless, even if the individual interior areas are different, the total interior area of ​​the first and second loop arrangements may still be similar or equal.

[0078] 4C of the drawings illustrates a non-limiting embodiment of a figure-8 antenna array 400, namely a first antenna 402, a second antenna 404, a third antenna 406 and a fourth antenna 408. Each figure-8 antenna includes two loops, which avoid placement of portions of the antenna coil adjacent to each other.

[0079] 4D illustrates the relative placement of antenna array 400 with respect to container sections 410 within area 412, such as with respect to trays on a shelf. A first loop of each antenna coil is positioned relative to a first pair of trays and a second loop of each antenna coil is positioned relative to a second pair of trays that is different from the first pair.

[0080] In this example, the antenna array 400 is arranged for five blood trays (labeled A, B, C, D, E) such that each tray is associated with a particular combination of antenna coils. For example, the top halves of trays A and B are located in a first zone 414 defined by the first loop 402a of the first antenna 402. The bottom halves of trays A and B are located in a second zone 416 defined by the second loop 406b of the third antenna 406. Similarly, the top halves of trays C and D are located in a third zone 418 defined by the first loop 406a of the third antenna 406. The bottom halves of trays C and D are located in a fourth zone 419 defined by the second loop 402b of the first antenna 402. As shown in Table 1, the RFID tag detected by the first antenna coil 402 and the third antenna coil 406 can thus be located in any one of trays A, B, C, or D. [Table 1] Table 1: Antenna coil - container section - mapping

[0081] The antenna array 400 can only provide a coarse location identification of the tag within a tray, but cannot identify the exact location, such as the particular tray, on which the tagged article resides.

[0082] FIG. 5A shows a non-limiting embodiment of a novel arrangement of antenna coils 500. The antenna coil arrangement consists of a series of antenna coils 502, each of which includes a first loop with a first current and a second loop with a second current that is rotationally opposite to the first current. In contrast to the antenna array 400 shown in FIG. 4C, the two loops of each antenna coil are positionable relative to the same set of trays. For example, with reference to the first antenna coil 504, the first loop 504a is adjacent to the second loop 504b, and a portion 506 of the first loop 504a is positioned alongside a portion 508 of the second loop 504b such that the direction of the current in both portions is the same.

[0083] In this example, there are four antenna coils 504, 524, 534, 544. The arrangement 500 is configured as follows: a first read zone 510 is formed across a first edge of the arrangement; a second read zone 512 is formed across a more or less central region of the arrangement of antenna coils 500; and a third read zone 514 is formed across a second opposite edge of the arrangement. With reference to the axes shown in FIG. 2A, the conductive portion of the antenna coil arranged substantially in the direction of the X-axis results in a magnetic field in the read zone above and below the conductive portion and in the tray, which is substantially in the direction of the Z-axis. The magnetic field thus oriented couples with (and thus allows the RFID reader 104 to read) the RFID tag antenna arranged substantially in the XY plane.

[0084] 5B illustrates the placement of antenna coils 500 relative to six container sections 522 in an area 520, such as six trays on a shelf (labeled A through F). Each antenna coil 502 is positioned within the area 520 such that both loops of the antenna coil are associated with the same container section 522 (this exemplary, non-limiting embodiment shows two container sections associated with both loops of the same antenna coil). For example, a first loop 504a and a second loop 504b of a first figure-eight shaped antenna coil 504 are both associated with trays A and B and contribute to read zones 510, 512, 514 across the top, middle, and bottom of trays A and B, as illustrated in FIG. 5B.

[0085] The arrangement of antenna coils 500 includes an overlapping series of antenna coils 502 to form a predefined combination of antenna coils associated with each container section. Each antenna coil is activated one at a time so that the RFID reader 104 can ascertain which tag is within a read zone associated with a predefined combination of one or more antennas. In this exemplary non-limiting embodiment, the predefined association includes either a single antenna or a combination of two antennas. Mapping antenna coils to container sections means that each container section can be uniquely identified as a tag location, as described in Table 2. [Table 2] Table 2: Antenna coil - container section - mapping

[0086] Advantageously, in this configuration, two antenna coils can be used to uniquely identify a location within the three trays, i.e., the number of antenna coils is less than the number of trays.

[0087] 5C, in this exemplary non-limiting embodiment, both the first RFID tag 550 on tray A and the second RFID tag 552 on tray B can be read by the first antenna coil 504. However, the second antenna coil 524 cannot read the first RFID tag 550, but can read the second RFID tag 552 on tray B. Thus, by cycling through each of the FIG. 8 antennas one at a time, and based on which antenna identifies the tag, it can be determined that the first RFID tag 550 is on tray A and the second RFID tag 552 is on tray B, using logic such as that defined in Table 2.

[0088] Advantageously, in the non-limiting embodiment shown in Figures 5A-5C, each figure-of-eight shaped antenna coil provides a far-field effect that reduces the total EMC due to the opposing directions of the magnetic fields in each half of the antenna coil, while in the near field, the magnetic field associated with each loop of the antenna coil remains sufficient to identify tags within read range of the antenna coil.

[0089] A drawback of this configuration is that the resulting RF read surface is not consistent across the conductive portions, since in the near field a stronger magnetic field is created in the center region than at the ends. The electric field in the center read zone 512 is stronger and has a larger range than the electric field in the end read zones 510, 514 due to two adjacent conductive portions (e.g., portion 506 of the first loop 504a arranged side-by-side with portion 508 of the second loop 504b, as shown in FIG. 5A). In some applications, this may be beneficial, such as when it is known that RFID tags in a tray are likely to be located within this center zone. However, in other applications, it may be undesirable to have a non-constant magnetic field strength at different locations in the tray. For example, one result may be that the larger, center read zone 512 extends to shelves above and / or below the shelves for which the antenna arrangement 500 is intended. In some applications, this may not be beneficial.

[0090] 6A illustrates the operation of one figure-of-eight shaped antenna coil 600 (such as the first antenna coil 504 in FIG. 5A). The conductive portions 602 of the antenna coil 600 extending in the X-axis direction generate a magnetic field 604 around each conductive portion 602, forming a read zone 606 above and below the conductive portions 602 capable of reading the tag antenna 209 on the RFID tag 208 that is substantially in the XY plane.

[0091] FIG. 6B illustrates the operation of another non-limiting embodiment of the antenna coil 610. The first and second loop arrangements form a sequence of spaced antenna loops. The sequence includes two antenna loops in a figure-of-eight shape. The two antenna loops have substantially the same internal area. In this example, the two loops 612, 614 of the figure-of-eight antenna coil are separated by a distance 616. The two loops of the antenna coil may be conductively connected in various ways, and in an exemplary non-limiting embodiment, the antenna coil 610 is B-shaped with the connection between the first and second loops located on one side (rather than in the middle), thereby forming a glasses-type structure. In this non-limiting embodiment, the antenna coil 610 is asymmetric, and the connection 615 between the two spaced loops 612, 614 is located along one longitudinal direction of the antenna coil 610 and is offset. Conductive portions 602 of an antenna coil 610 extending along the X-axis generate a magnetic field 604 around each conductive portion 602 , forming a read zone 606 , which is the area in which an RFID tag can be located by the antenna coil 610 .

[0092] As shown in Figure 6C, the figure-8 shaped antenna coil 600 provides three read zones 606. The central zone 620 is slightly larger than the end zones 622, 624. This is conceptually illustrated as the end zones 622, 624 being sized to read three tagged articles 626, while the central zone 620 (due to its two parallel adjacent conductive portions) is sized to read four tagged articles 626. In an exemplary non-limiting embodiment, articles 626 located outside the read zone, i.e., in regions 628 and 630, cannot be read by the figure-8 shaped antenna coil 600 because the magnetic field is perpendicular to the plane in which the antenna coil lies (i.e., the XZ plane).

[0093] As shown in Figure 6D, an antenna coil 610 with spaced loops advantageously has a larger central read zone 640 as well as a more uniform read zone magnetic field strength (i.e., less intense in the central read zone compared to the end read zones). In Figure 6D, the central read zone 640 is illustrated as being conceptually large enough to read about six tagged articles 626, i.e., twice as large as the end zones 622, 624.

[0094] Overlapping antenna coil arrays

[0095] In some non-limiting embodiments, one antenna coil (such as the non-limiting embodiment illustrated in FIG. 6A or the non-limiting embodiment illustrated in FIG. 6B) will change direction through the read zone as the magnetic field curves around the conductor, but two antenna coil loops may be shaped and sized to have conductive portions substantially parallel to the X direction that are spaced apart such that a continuous read zone can be provided by a single antenna coil.

[0096] In other non-limiting embodiments, if the antenna coil is configured such that the resulting read zone is smaller than the area in which reading is desired (e.g., smaller than the tray holding the tagged articles), then two or more antenna coils can be positioned to cover the required area, such as when a magnetic field in the Z direction is required that is not available at the center of an antenna coil positioned in the XZ plane.

[0097] 7A and 7C of the drawings, a radio frequency (RF) antenna array 704 includes at least one set of first coplanar antenna coils 700, 702. Each antenna coil includes a first loop 701 having a first current and a second loop 703 having a second current in a rotationally opposite direction to the first current. The first current induces a first magnetic field (H1) for detecting electronic tags in the near field. The second current induces a second magnetic field (-H2) for detecting electronic tags in the near field. The first magnetic field and the second magnetic field are in opposite directions such that the sum of the first magnetic field and the second magnetic field is substantially zero in the far field. H tot =H1-H2≒0 The antenna coils 700, 702 are arranged to overlap such that the loops are aligned along a first axis 731, thereby creating a first continuous read zone 730 along the first axis.

[0098] The first continuous read zone 730 includes a series 720 of interleaved read zones 718 generated by the antenna coils (in this example, generated by the first loop 701 and second loop 703 of each antenna coil 700, 702).

[0099] 7B and 7D, the first loop 701 and the second loop 703 of each antenna coil 706, 708 may be spaced apart to produce a read zone 718 of substantially uniform magnetic field strength.

[0100] The antenna coil may have substantially parallel conductive portions with two antenna coil loops spaced apart read zones. In some non-limiting embodiments, each antenna coil loop is sized such that the conductive portions across the cross section (i.e., horizontally across the tray) are spaced apart by a distance of approximately twice the width of the read zone. This spacing is useful when two similar antenna coils are arranged to overlap, as shown in FIG. 7A. That is, a first figure-8 shaped antenna coil 700 and a second figure-8 shaped antenna coil 702 are arranged to overlap to form a figure-8 shaped antenna coil arrangement 704. Similarly, a first antenna coil 706 and a second antenna coil 708 with spaced loops are arranged to overlap to form an antenna coil arrangement 710, as shown in FIG. 7B. In both of these non-limiting embodiments, the antenna coils are arranged to overlap such that the conductive portions 712 of the two antenna coils are spaced apart by a distance 714 that is approximately the same as the width 716 of the read zone 718, as illustrated in FIGS. 7C and 7D. This spacing allows for a continuous series 720 of read zones 718. In both of these arrangements 704, 710, the first antenna coil 700, 706 forms a first series of read zones 722 and the second antenna coil 702, 708 forms a second series of read zones 724. The antenna coil arrangements 704, 710 are formed by first and second overlapping antenna coils whereby the first and second series of read zones 722, 724 are interleaved to form a continuous RFID antenna read zone 730, as shown in Figures 7C and 7D.

[0101] The antenna coils are switched sequentially, with one antenna coil being activated at any one time. For example, referring to antenna coil arrangement 710, the first antenna coil 706 is activated first. This activates a first series of read zones 722 that allow the RFID reader to detect tagged articles located within the first series of read zones 722. The second dog-bone shaped antenna coil 708 is then activated. This activates a second series of read zones 724 that allow the RFID reader to detect tagged articles located within the second series of read zones 724. In this manner, the RFID reader can unambiguously identify whether the tagged article is located within either the first series of read zones 722 or the second series of read zones 724.

[0102] A continuous RFID antenna read zone 730 means that tagged items can be identified anywhere within the container section in which the antenna array is located (e.g., tagged blood products on a tray with overlapping antenna arrays positioned along the length of the tray).

[0103] One advantage of the figure-of-eight shape with spaced loops, as seen in Figure 7D, is that it allows the same number of antennas to cover a larger read area, or in other words, fewer antenna coils are needed to cover the same RFID read area.

[0104] In FIG. 7B, the first and second loop arrangements form a sequence of spaced antenna loops, which create a read zone of substantially uniform magnetic field strength. In this example, the first loop 701 and the second loop 703 are of the same size. As a result, the first inner area is substantially the same as the second inner area. However, in a multi-loop antenna coil, the first loop may be of a different size relative to the second loop. However, the loops are sized such that, in total, the sum of the inner areas of the individual loops is substantially the same as the first inner area (sum) of the first loop arrangement and the second inner area (sum) of the second loop arrangement. In such a multi-loop antenna coil, the array can have either an even number of antenna loops or a non-even number of antenna loops. In the example shown in FIG. 7A to FIG. 7D, the array includes two antenna loops in a figure-of-eight shape, with the two antenna loops having substantially the same inner area.

[0105] For example, as shown in FIGS. 8A-8C, the RF antenna array 800 includes a first series 830 of coplanar antenna coils 802. Each antenna coil is comprised of one or more antenna coil loops 832. The antenna coils 802 are arranged to overlap such that the antenna coil loops 832 are aligned along a first axis 834. This creates a first continuous read zone 836 along the first axis that includes a series of interleaved read zones 816 created by the antenna coil loops of the first series 830. The RF antenna array 800 also includes a second series 840 of coplanar antenna coils 802. Each antenna coil is comprised of one or more antenna coil loops 832. The antenna coils are arranged to overlap such that the loops are aligned along a second axis 844. This creates a second continuous read zone 846 along the second axis that includes a series of interleaved read zones 816 created by the antenna coil loops of the second series 840. The second axis 844 is parallel to and spaced apart from the first axis 834. As a result, the first and second continuous read zones partially overlap to form a third continuous read zone 856.

[0106] In the examples of FIGS. 7A-7D and 8A-8C, the antenna coil includes a first loop arrangement including a first loop having a first current that induces a first magnetic field for detecting the electronic tag in the near field, and a second loop arrangement conductively connected to the first loop arrangement. The second loop arrangement includes a second loop having a second current that is rotationally opposite to the first current. The second current induces a second magnetic field for detecting the electronic tag in the near field. The first loop arrangement has a first inner region. The second loop arrangement has a second inner region such that the first magnetic field reduces the second magnetic field in the far field. In some non-limiting embodiments, the first magnetic field and the second magnetic field are in opposite directions such that the sum of the first magnetic field and the second magnetic field is substantially zero in the far field.

[0107] In the example of FIGS. 8A-8C , the RF antenna array 800 includes multiple laterally overlapping series 830, 840 of antenna coils 802 such that the series 830, 840 are aligned along the length l of a container section 812 of a container, and the RF antenna array 800 is positioned across the multiple container sections 812 (in the X direction, as indicated by the X-axis in FIG. 8A ).

[0108] In this non-limiting embodiment, the first series 830 includes two overlapping figure-8 shaped antenna coils 804, 806. The second series 840 includes two overlapping figure-8 shaped antenna coils 808, 810. A first continuous read zone 836 is associated with the first container section 1 and the second container section 2. A second continuous read zone 846 is associated with the second container section 2 and the third container section 3. A third continuous read zone 856 is associated with the second container section 2.

[0109] 8A illustrates a non-limiting embodiment of an RF antenna array 800 that includes multiple overlapping figure-of-eight shaped antenna coils 802. This exemplary non-limiting embodiment includes four antenna coils 804, 806, 808, 810 arranged such that three container sections 812 within an area 814 are each associated with a combination of read zones 816 created by the RF antenna array 800. The container sections 812 (which may be, for example, multiple trays on a shelf of a cabinet) are identifiable based on a unique combination of antenna coils, as set forth in Table 3. [Table 3] Table 3: Antenna coil-container section-mapping

[0110] In practice, since the antenna coils work in pairs to ensure continuous coverage along the length of the tray (as described with reference to Figures 7A-7D), the antenna coil-container section-mapping in Table 3 can be written as antenna coil pair-container section-mapping, as shown in Table 4. [Table 4] Table 4: Antenna coil pair-container section-mapping

[0111] Two antenna coil pairs are used to uniquely identify the location of the tag in the three container sections. In some non-limiting embodiments, the overlapping antenna coil configuration may consist of three or more antenna coils, and two antenna coil sets are used to identify the location of the tag in the three container sections. In some non-limiting embodiments, three or more antenna coil sets may be used to identify the location of the tag in the three or more container sections.

[0112] 8B shows a tray 820 placed in container section 1 to the left of the RF antenna array 800. A tagged article 822 in this tray 820 is read by the first antenna coil 804 and / or the second antenna coil 806 of the first antenna coil set. Thus, if only the first antenna coil 804 and / or the second antenna coil 806 receive a response signal from the tag antenna, the system 100 determines that the tagged article is located in container section 1.

[0113] 8C, a tray 820 is placed in center container section 2. A tagged article 822 in container section 2 is detected by all four antenna coils 802.

[0114] In some non-limiting embodiments, the read zones 816 do not overlap, as shown in Figure 8C. Referring to Table 3, in this non-limiting embodiment, tagged articles 822 in tray 820 are read by either the first antenna coil 804 or the second antenna coil 806. Similarly, in container section 3, tagged articles 822 are read by either the third antenna coil 808 or the fourth antenna coil 810. For container section 2, tagged articles 822 are read by both the first antenna coil 804 and the third antenna coil 808, or by the second antenna coil 806 and the fourth antenna coil 810.

[0115] In another non-limiting embodiment, the read zones 816 partially overlap, as shown in Figure 8B. Tagged articles located in the overlap zone 824 are read by multiple antenna coils.

[0116] In other non-limiting embodiments, as shown in FIG. 8A, the read zones may overlap such that all tagged articles 822 are read by multiple antenna coils 802.

[0117] Methodology Overview

[0118] 9 is a flow chart of a non-limiting embodiment of a method 900 for determining the location of an electronically tagged item. The method 900 determines the location of an item within a container section of a container using an RFID reader (e.g., an RFID reader including two or more overlapping antenna coil sets). The method includes a step 902 of individually activating each antenna coil of a set of overlapping antenna coils that form a continuous read zone individually associated with the container section, and a step 904 of receiving a plurality of response signals associated with the activated antenna coil combination from the set of antenna coils. The method further includes a step 906 of identifying a read zone responsive to the activated antenna coil combination, and a step 908 of identifying the container section as the location of the item based on the identified read zone.

[0119] Power Levels

[0120] In a container with multiple levels, such as multiple shelves or drawers, the reader antenna may couple with a tag antenna on either the shelf above the antenna or the shelf below the antenna. For example, referring to Figure 10, an RFID tag 1002 affixed to an item on shelf 0 may be identified by shelf 0 antenna 1004 and shelf 1 antenna 1006. In the illustrated example, because RFID tag 1002 is closer to shelf 0 antenna 1004, it will be identified by shelf 0 antenna 1004 at a lower field strength than the higher field strength required for shelf 1 antenna 1006.

[0121] In an exemplary non-limiting embodiment, the reader scans each antenna coil at multiple power levels and records the lowest power level required to see each tag. As shown in FIG. 10, the lowest power level to see the RFID tag 1002 is provided by the shelf 0 antenna 1004, which is closer to the RFID tag 1002. Upon completion of a complete scan (i.e., multiple power levels by each antenna), the reader will have a set of one or more targets for each tag at different power levels. The lowest power level, in an exemplary non-limiting embodiment, represents the most likely physical location of each tag, since the antenna arrangement is provided on each floor such that a tagged item placed on the floor will be closer to the antenna on that shelf than the antenna on the shelf above it. Each horizontal group of antenna coils is assigned a name that defines its relative position. This name is used when tag information is transmitted to end user applications.

[0122] 1, in some non-limiting embodiments, the antenna controller 106 operates each antenna coil 108 at a number of different power levels. The processor 110 receives a number of response signals respectively associated with the number of power levels and determines a container height level of the article based on the received response signals.

[0123] 9 of the drawings, optionally in the method, activating 902 the antenna coils includes activating each antenna coil at a plurality of different powers. Receiving 904 a plurality of response signals includes receiving a response signal associated with each antenna coil and each of the plurality of different powers. Identifying 908 the container section includes determining at which height level of the container the article is located in response to the plurality of response signals.

[0124] Thus, through a combination of magnetic flux strength control (through power level control) and software decision-making algorithms, the system is able to provide high resolution RFID tag location identification for multiple shelving systems.

[0125] It should be noted that the above outlines some of the more suitable non-limiting embodiments. It will be apparent to those skilled in the art that modifications to the disclosed non-limiting embodiments can be made without departing from the spirit and scope thereof. As such, the described non-limiting embodiments should be considered merely illustrative of some of the more prominent features and applications. Other beneficial results can be achieved by applying the non-limiting embodiments in different ways or modifying them in ways known to those skilled in the art. This includes mixing and matching features. Since elements and / or functions between various non-limiting embodiment(s) are expressly contemplated herein, those skilled in the art will understand from this disclosure that features, elements and / or functions of one non-limiting embodiment may be incorporated into another non-limiting embodiment as appropriate, unless otherwise noted above. Although the present specification describes specific arrangements and methods, the intent and concept may be suitably applied to other arrangements and applications.

[0126] In the following claims and the preceding description, unless otherwise required by context, express language or necessary implication, the word "comprise" or variations such as "comprises" or "comprising" are used in their inclusive sense, i.e., to identify the presence of stated features, but are not used to exclude the presence or addition of further features in various non-limiting embodiments.

Claims

1. 1. An RFID reader system (100) for determining the location of electronically tagged items within a container having multiple container sections, comprising: An RF antenna array (102); An RFID reader (104), the RF antenna array (102) comprises an arrangement of overlapping antenna coils (108) forming continuous read zones (730) individually associated with the container sections (210) of the container (200); The RFID reader (104) comprises an antenna controller (106) for individually activating each of the antenna coils, and a processor (110); The processor (110) receiving a plurality of response signals from the RF antenna array associated with activated combinations of the antenna coils; identifying a read zone responsive to the activated combination of said antenna coils; An RFID reader system that identifies a container section as the location of the electronically tagged item based on the identified read zone.

2. The RF antenna array includes: a first series of coplanar antenna coils and a second series of coplanar antenna coils; each antenna coil in the first series includes one or more antenna coil loops; the first series of antenna coils are arranged in an overlapping manner such that their antenna coil loops are aligned along a first axis, thereby creating a first contiguous read zone along the first axis having a series of interleaved read zones created by the first series of antenna coil loops; each antenna coil in the second series includes one or more antenna coil loops; the second series of antenna coils are arranged in an overlapping manner such that their antenna coil loops are aligned along a second axis, thereby creating a second continuous read zone along the second axis having a series of interleaved read zones created by the second series of antenna coil loops; 2. The RFID reader system of claim 1, wherein the second axis is parallel to and spaced from the first axis, and the first and second continuous read zones partially overlap to form a third continuous read zone.

3. the antenna coil comprises a first loop arrangement and a second loop arrangement conductively connected to the first loop arrangement; the first loop arrangement includes a first loop having a first current that induces a first magnetic field for detecting an electronic tag in a near field; the second loop arrangement includes a second loop having a second current flowing in an opposite rotational direction to the first current flow; the second current induces a second magnetic field for detecting an electronic tag in a near field; The first loop arrangement has a first inner region; the second loop arrangement has a second inner region; 3. The RFID reader system of claim 2, wherein the first magnetic field reduces the second magnetic field in the far field.

4. the first magnetic field and the second magnetic field are oriented in opposite directions; 4. The RFID reader system of claim 3, wherein a sum of the first magnetic field and the second magnetic field is substantially zero in the far field.

5. the first loop arrangement and the second loop arrangement form a sequence of spaced apart antenna loops; 5. The RFID reader system of claim 3 or 4, wherein the spaced antenna loops create a read zone of substantially uniform magnetic field strength.

6. the first loop is a different size than the second loop; 6. The RFID reader system of claim 5, wherein the first interior area is substantially the same as the second interior area.

7. 6. The RFID reader system of claim 5, wherein the sequence includes a non-even number of antenna loops.

8. 6. The RFID reader system of claim 5, wherein the sequence has a figure eight shape with two antenna loops having substantially the same inner area.

9. the first series includes two overlapping figure-of-eight antenna coils; the second series includes two overlapping figure-of-eight antenna coils; the first contiguous read zone is associated with a first container section and a second container section; the second contiguous read zone is associated with the second container section and a third container section; 9. The RFID reader system of claim 8, wherein the third continuous read zone is associated with the second container section.

10. 10. An RFID reader system according to any one of claims 3 to 9, characterized in that the number of loops and the inner area of ​​the loops cause the sum of the first magnetic field and the second magnetic field to be substantially zero in the far field.

11. 11. The RFID reader system of claim 1, wherein each of the contiguous read zones comprises a series of interleaved read zones generated by the antenna coil.

12. 12. The RFID reader system according to claim 1, wherein the continuous read zone has a magnetic field direction that detects electronic tags in a given upright orientation.

13. the RF antenna array includes a series of multiple laterally overlapping antenna coils; the series of antenna coils are aligned along a length of the container section; 13. The RFID reader system of claim 1, wherein the RF antenna array is disposed across a plurality of sections.

14. the antenna controller activates each of the antenna coils at a plurality of power levels; The processor, receiving a plurality of response signals respectively associated with the plurality of power levels; 14. The RFID reader system according to claim 1, further comprising a step of determining a height level of the container based on the plurality of received response signals.

15. 1. A method for determining the location of an electronically tagged item within a container section of a container using an RFID reader, comprising: individually activating each antenna coil of a set of overlapping antenna coils forming a continuous read zone individually associated with said container section; receiving a plurality of response signals associated with activated antenna coil combinations from the set of antenna coils; identifying a read zone responsive to an activated antenna coil combination; and identifying a container section as a location of the item based on the identified read zone.

16. wherein individually activating each of the antenna coils includes operating each of the antenna coils at a plurality of different powers; receiving the plurality of response signals includes receiving a response signal associated with each of the antenna coils for each of the plurality of different powers; 16. The method of claim 15, wherein identifying the container section includes determining a height level of the container in response to the plurality of response signals.

17. a first loop arrangement including a first loop having a first current that induces a first magnetic field for detecting an electronic tag in a near field; a second loop arrangement conductively connected to the first loop arrangement; the second loop arrangement includes a second loop having a second current flowing in an opposite rotational direction to the first current flow; the second current induces a second magnetic field for detecting an electronic tag in a near field; The first loop arrangement has a first inner region; the second loop arrangement has a second inner region; 11. An RF antenna coil, comprising: a first magnetic field that reduces the second magnetic field in a far field.

18. the first magnetic field and the second magnetic field are oriented in opposite directions; 20. The RF antenna coil of claim 17, wherein the sum of the first magnetic field and the second magnetic field is substantially zero in the far field.

19. The RF antenna coil of claim 18 , wherein the first loop arrangement and the second loop arrangement are substantially coplanar.

20. 20. An RF antenna coil as claimed in any one of claims 17 to 19, wherein the first loop arrangement and the second loop arrangement form a sequence of spaced antenna loops.

21. 21. The RF antenna coil of claim 20, wherein the sequence has a figure eight shape with two antenna loops having substantially the same inside area.

22. The RF antenna coil of claim 20 , wherein the sequence includes a non-even number of antenna loops.

23. the first loop is a different size than the second loop; 21. The RF antenna coil of claim 20, wherein the first inner region is substantially the same as the second inner region.

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