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 generally relates to determining the location of radio frequency identification (RFID) tags, and more particularly to systems and antenna arrangements for determining the location of an item with an RFID tag, and methods for determining the location of an item with an RFID tag.

Background Art

[0002] Radio frequency identification (RFID) is one of the radio frequency identification methods. Here, data is electronically stored on a tag, and the data is readable by an RFID reader to identify, locate, and / or track an item to which the tag is attached. RFID systems are not necessarily configured to provide the exact location of the tagged item. Instead, they often provide the general location of the tagged item. For example, when a tagged item is placed inside a cabinet, the RFID reader is often configured to confirm the presence of the tag inside the cabinet. In this case, it is not necessarily possible to confirm on which shelf or drawer inside the cabinet the tagged item is placed.

[0003] An RFID reader operates by generating an electrical signal, generating an electromagnetic field that interacts with the antenna coil of the RFID tag to interrogate the tag, and obtaining identification information from the tag. The reading range of an RFID reader depends on the strength of the reading signal. Electromagnetic interference (EMI), which is sometimes called radio frequency interference (RFI), is interference generated by an external source that affects an electrical circuit, such as by electromagnetic induction. Since EMI can potentially degrade the performance of an electrical circuit, electromagnetic compatibility (EMC) requirements and standards for limiting electromagnetic radiation from equipment exist for various types of electronic equipment. This ensures that when such equipment is used as intended, it does not interfere with the operation of other electronic equipment within a certain distance.

Summary of the Invention

Means for Solving the Problems

[0004] Nothing relating to the documents, actions, materials, apparatus, articles, etc. contained herein shall be construed as acknowledging that any or all of these matters constitute part of the prior art base in the art relating to this disclosure that existed prior to the priority date of each claim of this application, or were in general knowledge.

[0005] In one embodiment, an RFID reader system is provided for determining the location of electronically tagged articles in a container having multiple container sections. The system comprises an RF antenna array and an RFID reader. The RF antenna array comprises an array of overlapping antenna coils that form sequential reading zones individually associated with the container sections of the container. The RFID reader comprises an antenna controller that individually activates each of the antenna coils and a processor. The processor receives multiple response signals from the RF antenna array associated with combinations of activated antenna coils, identifies reading zones corresponding to the combinations of activated antenna coils, and identifies the container sections as locations of electronically tagged articles based on the identified reading zones.

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

[0007] The antenna coil may comprise a first loop configuration and a second loop configuration conductively connected to the first loop configuration. The first loop configuration includes a first loop having a first current that induces a first magnetic field for detecting electronic tags in the near field. The second loop configuration includes a second loop having a second current that rotates in the opposite direction to the first current. The second current induces a second magnetic field for detecting electronic tags in the near field. The first loop configuration has a first inner region. The second loop configuration 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 point in opposite directions, and the 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 sequence may have two antenna loops with substantially the same inner area, forming a figure-eight shape. The first series may include two overlapping figure-eight antenna coils, and the second series may include two overlapping figure-eight antenna coils.

[0010] The first continuous reading zone may be associated with the first and second container sections, the second continuous reading zone may be associated with the second and third container sections, and the third continuous reading zone may be associated with the second container section.

[0011] Depending on the number of loops and the area inside the loops, the sum of the first and second magnetic fields may be substantially zero in the far field.

[0012] Each of the continuous reading zones may include a series of interleaved reading zones generated by the antenna coil.

[0013] The continuous reading zone may have a magnetic field direction that detects electronic tags in a predetermined upright direction.

[0014] An RF antenna array may include a series of antenna coils that overlap laterally, and the series of antenna coils may be aligned along the length of a container section, and the RF antenna array may be arranged across multiple sections.

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

[0016] In another embodiment, a method is provided for determining the location of an electronically tagged article within a container section of a container using an RFID reader. This method includes the steps of: individually activating each antenna coil of a set of overlapping antenna coils that form a series of reading zones individually associated with the container section; receiving a plurality of response signals from the set of antenna coils associated with the activated combination of antenna coils; identifying a reading zone that responds to the activated combination of antenna coils; and identifying the container section as the location of the article based on the identified reading zone.

[0017] The step of individually activating each antenna coil may include the step of operating each antenna coil with multiple different powers. The step of receiving multiple response signals may include the step of receiving a response signal associated with each antenna coil for each of the multiple different powers. The step of identifying a container section may include the step of determining the height level of the container in response to the multiple response signals.

[0018] In another embodiment, an RF antenna coil is provided. This RF antenna coil comprises a first loop configuration including a first loop having a first current that induces a first magnetic field for detecting electronic tags in the near field, and a second loop configuration conductively connected to the first loop configuration. The second loop configuration includes a second loop having a second current that rotates in the opposite direction to the first current. The second current induces a second magnetic field for detecting electronic tags in the near field. The first loop configuration has a first inner region. The second loop configuration 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 oriented 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 an 8-shaped figure in which two antenna loops have substantially the same inner area.

[0023] The sequence may include an odd number of antenna loops.

[0024] The first loop may be of a different size from 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 skilled in the art by considering the following description of specific non-limiting embodiments in conjunction with the accompanying drawings.

[0026] The description made herein should be understood as being related to some non-limiting embodiments and is not intended to be a description of the entire invention. If there are any stipulations considered to be applicable to all non-limiting embodiments, the applicant / patentee reserves the right to later delete them from this specification and does not rely on these descriptions for patent acceptance or subsequent grant in any country.

Brief Description of the Drawings

[0027] A detailed description of exemplary (non-limiting) embodiments will be more fully understood by considering it in conjunction with the accompanying drawings.

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

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

[0030] [Figure 2B] Figure 2A is a schematic diagram of a tray inside the cabinet, which holds multiple tagged blood bags.

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

[0032] [Figure 2D] This is a schematic diagram of an RFID antenna that connects to an RFID tag placed in a magnetic field.

[0033] [Figure 3] This is a schematic diagram showing the antenna configuration of conventional technology.

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

[0035] [Figure 4B] This is a schematic diagram of a multiloop antenna coil.

[0036] [Figure 4C] This is a schematic diagram of an antenna array from prior art.

[0037] [Figure 4D] Figure 4C shows the arrangement of the antenna array relative to a container section in a certain region.

[0038] [Figure 5A] This is a schematic diagram of a non-limiting embodiment of the arrangement of the antenna coil.

[0039] [Figure 5B]This figure shows the arrangement of the antenna coil in Figure 5A relative to the container section within the region.

[0040] [Figure 5C] This figure shows the arrangement of the two antenna coils in Figure 5A relative to the two container sections in Figure 5B.

[0041] [Figure 6A] This figure shows the operation of an eight-shaped antenna coil according to one non-limiting embodiment.

[0042] [Figure 6B] This figure shows the operation of another non-limiting embodiment of the antenna coil.

[0043] [Figure 6C] Figure 6A is a schematic diagram of an eight-shaped antenna coil applied to a container for holding tagged items.

[0044] [Figure 6D] Figure 6B is a schematic diagram of an antenna coil applied to a container that holds tagged items.

[0045] [Figure 7A] This is a schematic diagram of a first non-limiting embodiment of the antenna arrangement.

[0046] [Figure 7B] This is a schematic diagram of a second non-limiting embodiment of the antenna arrangement.

[0047] [Figure 7C] This figure shows the operation of the first non-limiting embodiment shown in Figure 7A.

[0048] [Figure 7D] This figure shows the operation of the second non-limiting embodiment shown in Figure 7B.

[0049] [Figure 8A]This is a schematic diagram of another non-limiting embodiment of the antenna arrangement.

[0050] [Figure 8B] This diagram shows the operation of the antenna configuration shown in Figure 8A.

[0051] [Figure 8C] This diagram shows the operation of the antenna configuration shown in Figure 8A.

[0052] [Figure 9] This is a flowchart of a non-limiting embodiment of a method for determining the position of items within a container section of a container.

[0053] [Figure 10] This is a schematic diagram of a non-limiting embodiment of a multi-shelf on which antennas are arranged.

[0054] In drawings, similar reference numerals indicate similar parts.

[0055] The drawings are not necessarily to scale and may be illustrated with phantom lines, perspective views, and fragmentary diagrams. In certain examples, details not necessary for understanding the non-limiting embodiments, or details that would make it difficult to perceive other details, may be omitted. [Modes for carrying out the invention]

[0056] Antenna system

[0057] Next, various non-limiting embodiments of methods and systems for determining the location of articles within a storage system will be described in detail. Other non-limiting embodiments, modifications, and equivalents will be apparent to those skilled in the art in view of the non-limiting embodiments disclosed herein, and these variations should be considered to fall within the scope of the appended claims.

[0058] Furthermore, it will be recognized by those skilled in the art that certain structural and operational details of the non-limiting embodiments (one or more) described below may be modified or omitted entirely (i.e., are not essential). In other examples, well-known methods, procedures, and components are not described in detail.

[0059] Figure 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 electronically tagged articles in a container having multiple container sections. The RFID reader system 100 has a radio frequency (RF) antenna array 102 that communicates with an RFID reader 104. The RF antenna array 102 includes an array of overlapping antenna coils 108 that form continuous reading zones 730 individually associated with container sections 210 of a container 200, as will be described in more detail elsewhere in this specification with reference to, for example, Figures 2 and 7. The RFID reader 104 comprises 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 reading zones that respond to combinations of activated antenna coils and, based on the identified reading zones, identifies container sections as locations of articles.

[0060] The response signal is generated in response to the query signal from the RFID reader 104. The RF antenna array 102 generates a series of reading zones, each of which is associated with a container section of the container, as will be described in more detail elsewhere in this specification.

[0061] In some non-limiting embodiments, the antenna controller and processor may be located in a single shared processing unit. In addition to the antenna controller 106 and 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 the following: 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., in the form of a network interface controller or other 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] Referring to Figure 2A of the drawings, an example of a container 202 in which articles 204 may be placed is a trolley or cabinet 200, where articles 204 in this example are plasma boxes or blood bags 206 to which electronic tags in the form of RFID tags 208 are attached. Each blood bag 206 is placed at a cabinet level (e.g., inside a drawer or on a shelf 214). Each tagged article 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 (arranged vertically so as to be labeled by the Y axis), where 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 (arranged horizontally so as to be labeled by the X axis). As shown in Figure 2B, each tray 212 is elongated and holds multiple RFID-tagged blood bags 206 stacked longitudinally across the tray 212, spanning the depth of the cabinet 200 (as labeled by the Z-axis). Figure 2C shows each blood bag 206 having 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 antenna 209 of the RFID tag 208 is substantially in the XY plane. In alternative, non-limiting embodiments, the trays may be arranged and / or stacked in various alternative configurations, for example, each shelf may include two parallel rows of trays.

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

[0064] Figure 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 shown as a dashed line, and its direction is indicated as curving around the antenna coil 108. In the regions above and below the antenna coil 108, the magnetic field curves to be approximately parallel to the plane on which the antenna coil 108 lies. The direction of the magnetic field in these regions facilitates coupling with the tag antenna 209, which is oriented more or less perpendicular to the orientation of the reader's antenna coil 108. Thus, in examples where the antenna coil 108 is placed in, above, below (or otherwise in the same plane as) a container drawer, tray, or shelf floor (the XY plane in the example shown in Figure 2D), the tag is positioned upright within the container so that the tag 208 is oriented perpendicular to the floor of the container drawer. A tray or shelf (in the example shown in Figure 2D, the tags are oriented in the YZ plane, but this may be any plane parallel to the Z axis) can couple with the magnetic field 220 when the tags are placed in a region above or below the reader antenna 108. This region above and / or below the antenna coil is referred to herein as the “reading zone.” In contrast, if the 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 becomes substantially parallel to the orientation of the tag antenna 209, and coupling is reduced or even absent. As a result, tagged items placed in such a more central region or zone cannot be located by the RFID reader 104. Thus, this central region is considered a “dead zone,” i.e., a region where there is no reading area for this particular antenna coil.

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

[0066] Antenna array

[0067] In some non-limiting embodiments, the antenna coil 108 in the system 100 is positioned to precisely determine the position of an article. In some non-limiting embodiments, the antenna coil 108 in the system 100 is positioned to reduce radio radiation to reduce far-range EMI, for example, to meet EMC requirements. At the same time, the antenna coil 108 is positioned to ensure sufficient electric field strength and operating range in the near field close to the antenna coil 108.

[0068] Figure 3 is a schematic diagram of a prior art antenna configuration 300. In this example, two antenna coils 302 are arranged for 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, that RFID tag may be placed in one 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, that RFID tag may be placed in one of the two trays 314, 316 associated with the second antenna coil 312. Therefore, in this antenna configuration 300, it is impossible to precisely place an RFID tag within one of the four trays.

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

[0070] Figure 4A shows a non-limiting embodiment of an antenna configuration 420 in which the antenna coil 422 is arranged to form an eight-shaped loop having 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 the antenna coil portions 422, such as portions 422a, 422b, being adjacent to each other. This minimizes near-field cancellation. In this way, the eight-shaped antenna coil 422 can provide additional conductive portions (compared to, for example, each of the antenna coils 302 in Figure 3), which can improve the accuracy of the antenna operation.

[0071] Antenna coil 422 includes two loops 424 and 426 arranged in a figure-eight antenna structure, with reverse-rotating currents flowing through each loop. This has two advantages. First, because the loops are sufficiently far apart, the near-field electric field strength and operating range are optimized. Second, because the currents in the two loops 424 and 426 flow in opposite directions, the far-field magnetic fields cancel each other out. This is done to meet global emission regulations (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 in the far field, or even become substantially zero. Various non-limiting embodiments of such antenna arrays are described herein.

[0073] Figure 4B shows a non-limiting embodiment of a multiloop antenna coil. The radio frequency (RF) antenna coil 430 has a first loop arrangement 432 including a first loop 432.1 (in this example, including two loops 432.1 and 432.2). The loops of the first loop arrangement 432 have a first current 436 that induces a first magnetic field +H for detecting an electronic tag in the near field. The antenna coil 430 also has a second loop arrangement 442 conductively connected to the first loop arrangement 432 (at a connection 444). The second loop arrangement 442 includes a second loop 442.1 (in this example, including two loops 442.1 and 442.2) having 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 an electronic tag in the near field. The first loop configuration 432 has a first inner region A1, and the second loop configuration has a second inner region A2, where the first magnetic field +H reduces the second magnetic field -H in the far field. The dimensions of the first inner region A1 are the sum of the inner areas of the first loops 432.1 and 432.2. The dimensions of the second inner region A2 are the sum of the inner areas of the second loops 442.1 and 442.2.

[0074] The magnetic field strength H is given by 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 passing through a surface is the surface integral of the normal component of the magnetic field B on that surface.

number

[0075] Accordingly, in some non-limiting embodiments of the double or multiloop 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 easily achieve this, in some non-limiting embodiments, the first loop configuration and the second loop configuration are substantially coplanar.

[0076] In a multiloop antenna coil, the first loop configuration includes all loops contributing to the first magnetic field. The second loop configuration includes all loops contributing to the second magnetic field. The first and second loop configurations form a sequence of antenna loops. The sequence may include an even or non-even number of antenna loops.

[0077] In some non-limiting embodiments, the first loop is made different in size from the second loop such that the first inner area is substantially the same as the second inner area. However, the loops may be the same size or different in size, and as a result, the inner areas of the individual loops may be the same or different. Nevertheless, even if the individual inner areas are different, the total inner areas of the first and second loop arrangements may still be similar or equal.

[0078] Figure 4C of the drawings shows a non-limiting embodiment of the figure-eight antenna array 400, namely, a first antenna 402, a second antenna 404, a third antenna 406, and a fourth antenna 408. Each figure-eight antenna includes two loops, which avoid the arrangement of adjacent antenna coil portions.

[0079] Figure 4D shows the relative arrangement of the antenna array 400 with respect to the container section 410 within region 412, for example, relative to trays on a shelf. The first loop of each antenna coil is positioned relative to a first pair of trays, and the 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, and E) such that each tray is associated with a specific combination of antenna coils. For example, the upper 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 lower 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 upper 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 lower 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, RFID tags detected by the first antenna coil 402 and the third antenna coil 406 can therefore be located within 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 coarse position identification of tags within a tray, and cannot identify the precise location of tagged items, such as a specific tray.

[0082] Figure 5A shows a non-limiting embodiment of a novel array of antenna coils 500. The array of antenna coils consists of a series of antenna coils 502, each antenna coil including a first loop having a first current and a second loop having a second current rotationally opposite to the first current. In contrast to the antenna array 400 shown in Figure 4C, the two loops of each antenna coil are positionable relative to the same set of trays. Referring to the first antenna coil 504, for example, 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 is the same in both portions.

[0083] In this example, there are four antenna coils 504, 524, 534, and 544. The arrangement 500 is configured as follows: a first reading zone 510 is formed across the first edge of the arrangement; a second reading zone 512 is formed across the more or less central region of the arrangement of antenna coils 500; and a third reading zone 514 is formed across the second opposite edge of the arrangement. Referring to the axes shown in Figure 2A, the conductive portion of the antenna coil, which is substantially oriented in the direction of the X axis, brings forth magnetic fields above and below the conductive portion, as well as in the reading zones which are substantially oriented in the direction of the Z axis within the tray. These oriented magnetic fields couple with the RFID tag antennas which are substantially oriented in the XY plane (thus enabling the RFID reader 104 to read them).

[0084] Figure 5B shows the arrangement of antenna coils 500 to six container sections 522 within a region 520, such as six trays on a shelf (labeled A through F). Each antenna coil 502 is positioned within the region 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, the first loop 504a and the second loop 504b of a first figure-eight antenna coil 504 are both associated with trays A and B and contribute to reading zones 510, 512, and 514 that traverse the top, middle, and bottom of trays A and B, as shown in Figure 5B.

[0085] The arrangement of the antenna coils 500 includes an overlap of a 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 determine which tags are in a reading zone associated with one or more predefined combinations of antennas. In this exemplary, non-limiting embodiment, the predefined associations include either a single antenna or a combination of two antennas. Mapping the antenna coils to the container sections means that each container section can be uniquely identified as a tag location, as shown in Table 2. [Table 2] Table 2: Antenna coil-container section-mapping

[0086] Advantageously, this configuration allows for the unique identification of the position within the three trays using only two antenna coils. In other words, the number of antenna coils is less than the number of trays.

[0087] Referring to Figure 5C, in this exemplary, non-limiting embodiment, both the first RFID tag 550 in tray A and the second RFID tag 552 in 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 it can read the second RFID tag 552 in tray B. Thus, by circulating each antenna in Figure 8 one at a time, it can be determined, based on which antenna identifies the tag, that the first RFID tag 550 is in tray A and the second RFID tag 552 is in tray B using logic as defined in Table 2.

[0088] Advantageously, in the non-limiting embodiments shown in Figures 5A-5C, each figure-eight antenna coil provides a far-field effect that reduces the total EMC due to the opposing direction of the magnetic field in each half of the antenna coil. At the same time, in the near field, the magnetic field associated with each loop of the antenna coil remains sufficient to identify tags within the reading range from the antenna coil.

[0089] A drawback of this configuration is that, in the near field, a stronger magnetic field is formed in the central region than at the ends, resulting in an inconsistent RF reading surface across the conductive portion. The electric field of the central reading zone 512 is stronger and extends over a larger area than the electric fields of the end reading zones 510, 514, due to two adjacent conductive portions (e.g., portion 506 of the first loop 504a, positioned alongside portion 508 of the second loop 504b, as shown in Figure 5A). In some applications, this can be beneficial, such as when it is known that RFID tags in a tray are likely to be located within this central zone. However, in other applications, the inconsistent strength of the magnetic field at different locations within the tray may be undesirable. For example, one consequence may be that a larger, central reading zone 512 extends to shelves above and / or below the shelf where the antenna arrangement 500 is intended. In some applications, this may not be beneficial.

[0090] Figure 6A shows the operation of one figure-eight shaped antenna coil 600 (such as the first antenna coil 504 in Figure 5A). The conductive portion 602 of the antenna coil 600, which extends in the X-axis direction, generates a magnetic field 604 around each conductive portion 602, forming reading zones 606 above and below the conductive portion 602, which allow the tag antenna 209 on the RFID tag 208, which is substantially in the XY plane, to be read.

[0091] Figure 6B shows the operation of another non-limiting embodiment of the antenna coil 610. The first and second loop arrangements form a sequence of spaced-out antenna loops. The sequence includes two figure-eight shaped antenna loops. The two antenna loops have substantially the same internal area. In this example, the two loops 612 and 614 of the figure-eight shaped antenna coil are separated by a distance of 616. The two loops of the antenna coil may be conductively connected in various ways, and in the 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 center), thereby forming a spectacle-shaped structure. In this non-limiting embodiment, the antenna coil 610 is asymmetrical, and the connection 615 between the two spaced-out loops 612 and 614 is located along one longitudinal direction of the antenna coil 610 and is offset. The conductive portion 602 of the antenna coil 610, which extends in the X-axis direction, generates a magnetic field 604 around each conductive portion 602, forming a reading zone 606, which is an area where the RFID tag can be positioned by the antenna coil 610.

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

[0093] As shown in Figure 6D, the antenna coil 610 with spaced-out loops is advantageous not only in having a larger central reading zone 640, but also in having a more uniform magnetic field strength in the reading zone (i.e., not as strong in the central reading zone compared to the edge reading zones). In Figure 6D, the central reading zone 640 is conceptually shown as being large enough to read about six tagged items 626, i.e., twice the size of the edge 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 Figure 6A or the non-limiting embodiment illustrated in Figure 6B) will have its orientation changed through the reading zone as the magnetic field curves around the conductor, but two antenna coil loops may be shaped and sized such that they have conductive portions that are spaced apart and substantially parallel to the X direction so that a single antenna coil can provide a continuous reading zone.

[0096] In other non-limiting embodiments, if the antenna coils are configured such that the resulting reading zone is smaller than the area to be read (for example, smaller than the tray holding the tagged items), two or more antenna coils can be arranged to cover the required area. This is the case, for example, when a magnetic field in the Z direction is required that cannot be obtained at the center of an antenna coil positioned in the XZ plane.

[0097] Referring to Figures 7A and 7C of the drawings, the radio frequency (RF) antenna array 704 includes at least one pair 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 rotationally opposite 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 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. H tot =H1-H2≈0 Antenna coils 700 and 702 are positioned to overlap so that their loops are aligned along the first axis 731, thereby generating a first continuous reading zone 730 along the first axis.

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

[0099] Referring to the antenna coil arrangement 710 shown in Figures 7B and 7D, the first loop 701 and the second loop 703 of each antenna coil 706, 708 may be spaced apart. This generates a substantially uniform magnetic field strength reading zone 718.

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

[0101] The antenna coils are switched sequentially, and one antenna coil is activated at any given time. For example, referring to antenna coil configuration 710, the first antenna coil 706 is activated first. This activates a first set of reading zones 722, which enables the RFID reader to detect tagged items located within the first set of reading zones 722. After this, the second dogbone-shaped antenna coil 708 is activated. This activates a second set of reading zones 724, which enables the RFID reader to detect tagged items located within the second set of reading zones 724. In this way, the RFID reader can clearly identify whether the location of a tagged item is within the first set of reading zones 722 or the second set of reading zones 724.

[0102] The continuous RFID antenna reading zone 730 means that tagged items located anywhere within the container section where the antenna array is positioned can be identified (for example, tagged blood products on a tray with overlapping antenna arrays positioned along the length of the tray).

[0103] As shown in Figure 7D, one advantage of the figure-eight configuration with spaced-out loops is that it can cover a wider reading area with the same number of antennas. In other words, fewer antenna coils are needed to cover the same RFID reading area.

[0104] In Figure 7B, the first and second loop configurations form a sequence of spaced antenna loops, which create a substantially uniform magnetic field strength reading zone. In this example, the first loop 701 and the second loop 703 are the same size. As a result, the inner area of ​​the first loop is substantially the same as the inner area of ​​the second loop. However, in a multiloop antenna coil, the first loop may be a different size from the second loop. However, the loop sizes are set such that, in total, the sum of the inner areas of the individual loops is substantially the same as the sum of the first inner area of ​​the first loop configuration and the sum of the second inner area of ​​the second loop configuration. In such a multiloop 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 Figures 7A to 7D, the array includes two figure-eight shaped antenna loops, where the two antenna loops have substantially the same inner area.

[0105] For example, as shown in Figures 8A-8C, the RF antenna array 800 includes a first series 830 of coplanar antenna coils 802. Each antenna coil consists of one or more antenna coil loops 832. The antenna coils 802 are arranged so that the antenna coil loops 832 overlap and align along a first axis 834. This generates a first continuous reading zone 836 along the first axis, which includes a series of interleaved reading zones 816 generated 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 consists of one or more antenna coil loops 832. The antenna coils are arranged so that the loops overlap and align along a second axis 844. This generates a second continuous reading zone 846 along the second axis, which includes a series of interleaved reading zones 816 generated by the antenna coil loops of the second series 840. The second axis 844 is parallel to the first axis 834 and is positioned at a distance from the first axis 834. As a result, the first continuous reading zone and the second continuous reading zone partially overlap to form the third continuous reading zone 856.

[0106] In the embodiments shown in Figures 7A-7D and 8A-8C, the antenna coil includes a first loop configuration having a first current that induces a first magnetic field for detecting electronic tags in the near field, and a second loop configuration conductively connected to the first loop configuration. The second loop configuration includes a second loop having a second current that rotates in the opposite direction to the first current. The second current induces a second magnetic field for detecting electronic tags in the near field. The first loop configuration has a first inner region. The second loop configuration 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 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.

[0107] In the examples of Figures 8A-8C, the RF antenna array 800 includes series 830, 840 that overlap multiple times laterally with the antenna coil 802, such that series 830, 840 are aligned along the length l of the container section 812 of the container, and the RF antenna array 800 is positioned across multiple container sections 812 (in the X direction as indicated by the X-axis in Figure 8A).

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

[0109] Figure 8A shows a non-limiting embodiment of an RF antenna array 800 including multiple overlapping figure-eight shaped antenna coils 802. This exemplary non-limiting embodiment includes four antenna coils 804, 806, 808, and 810, arranged such that three container sections 812 within region 814 are each associated with a combination of reading zones 816 created by the RF antenna array 800. The container sections 812 (which may be, for example, multiple trays on a cabinet shelf) are identifiable based on a unique combination of antenna coils, as shown 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 explained with reference to Figures 7A-7D), the antenna coil-container section-mapping in Table 3 can be described as antenna coil pair-container section-mapping, as shown in Table 4. [Table 4] Table 4: Antenna coil pair-container section-mapping

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

[0112] Figure 8B shows a tray 820 placed in container section 1 on the left side of the RF antenna array 800. Tagged items 822 in this tray 820 are read by the first antenna coil 804 and / or the second antenna coil 806 of the first set of antenna coils. Therefore, if only the first antenna coil 804 and / or the second antenna coil 806 receive a response signal from the tagged antenna, the system 100 determines that the tagged item is located in container section 1.

[0113] In Figure 8C, tray 820 is placed in the central container section 2. Tagged items 822 in container section 2 are detected by all four antenna coils 802.

[0114] In some non-limiting embodiments, the reading 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 either 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 other non-limiting embodiments, the reading zones 816 partially overlap, as shown in Figure 8B. Tagged items located in the overlapping zone 824 are read by multiple antenna coils.

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

[0117] Method Overview

[0118] Figure 9 is a flowchart of a non-limiting embodiment of a method 900 for determining the location of an electronically tagged article. The method 900 uses an RFID reader (e.g., an RFID reader including a set of two or more overlapping antenna coils) to determine the location of an article within a container section of a container. The method includes the steps of: individually activating each antenna coil of a set of overlapping antenna coils that form a continuous reading zone individually associated with the container section; and receiving a plurality of response signals from the set of antenna coils associated with the activated antenna coil combination. The method further includes the steps of: identifying a reading zone that responds to the activated antenna coil combination; and identifying the container section as the location of an article based on the identified reading zone.

[0119] Power level

[0120] In containers with multiple levels, such as multiple shelves or drawers, a leader antenna may be coupled with a tag antenna located either on a shelf above or below the antenna. For example, referring to Figure 10, an RFID tag 1002 attached to an item on shelf 0 may be identified by shelf 0 antenna 1004 and shelf 1 antenna 1006. In the illustrated example, because the RFID tag 1002 is close to shelf 0 antenna 1004, it is identified by shelf 0 antenna 1004 with a lower electric field strength than the high electric 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 view each tag. As shown in Figure 10, the lowest power level for viewing RFID tag 1002 is provided by shelf antenna 1004, which is closer to RFID tag 1002. Once a complete scan (i.e., scanning at multiple power levels by each antenna) is complete, the reader will have one or more sets of sights for each tag at different power levels. The lowest power level indicates the most likely physical location of each tag in the exemplary, non-limiting embodiment, because the antenna arrangement is set up on the floor of each level so that a tagged item placed on the floor is closer to the shelf antenna than to the shelf antenna 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 the end-user application.

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

[0123] Referring again to Figure 9 of the drawings, selectively in this method, step 902 of activating the antenna coils includes the step of activating each antenna coil with a plurality of different powers. Step 904 of receiving a plurality of response signals includes the step of receiving a response signal associated with each antenna coil and each of the plurality of different powers. Step 908 of identifying a container section includes the step of determining, in response to the plurality of response signals, at what height level in the container the goods are located.

[0124] Thus, by combining magnetic flux intensity control (through power level control) with a software-based decision-making algorithm, this system can provide high-resolution RFID tag location identification for multiple shelf systems.

[0125] It should be noted that some more appropriate non-limiting embodiments have been outlined above. It will be apparent to those skilled in the art that modifications to the disclosed non-limiting embodiments can be made without departing from their spirit and scope. Thus, the described non-limiting embodiments should be considered merely illustrative of some of the more prominent features and uses. Other beneficial results can be achieved by applying the non-limiting embodiments in different ways or by 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 embodiments (one or more) are expressly constrained 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 stated above. While this specification describes specific arrangements and methods, its intent and concepts can be suitably applied to other arrangements and uses.

[0126] In the subsequent claims and prior description, unless otherwise required by contextual, explicit wording or necessary implied meaning, the word “comprise” or variations such as “comprises” or “comprising” are used in a comprehensive sense, that is, to identify the presence of the described features, but not to exclude the presence or addition of further features in various non-limiting embodiments.

Claims

1. An RFID reader system for determining the location of electronically tagged items in a container having multiple container sections and reducing the magnetic field in the far field, RF antenna array and Equipped with an RFID reader, The RF antenna array comprises an array of overlapping antenna coils that form continuous reading zones individually associated with container sections of the container, The RFID reader comprises an antenna controller that individually activates each of the antenna coils, and a processor. The aforementioned processor, From the RF antenna array, multiple response signals associated with the activated combination of antenna coils are received. Identify the reading zones that respond to the activated combination of antenna coils, Based on the identified reading zone, the container section is identified as the location of the electronically tagged article. The antenna coil comprises a first loop configuration and a second loop configuration electrically connected to the first loop configuration. The first loop configuration includes a first loop having a first current that induces a first magnetic field for detecting an electronic tag in the near field. The second loop configuration includes a second loop having a second current whose rotational direction is opposite to that of the first current. The second current induces a second magnetic field for detecting an electronic tag in the near field. The first loop configuration has a first inner region, The second loop configuration has a second inner region, As a result, the first magnetic field reduces the second magnetic field in the far field. The RF antenna array includes a series of antenna coils that overlap laterally, The series of antenna coils are aligned along the length of the container section, The RFID reader system is characterized in that the RF antenna array is arranged across multiple sections.

2. The RF antenna array is It comprises a first series of coplanar antenna coils and a second series of coplanar antenna coils, Each of the first series of antenna coils 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 generating a first continuous reading zone having a series of interleaved reading zones generated by the first series of antenna coil loops along the first axis. Each of the second series of antenna coils 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 the second axis, thereby generating a second continuous reading zone along the second axis, having a series of interleaved reading zones generated by the second series of antenna coil loops. The RFID reader system according to claim 1, characterized in that the second axis is parallel to the first axis and is spaced apart from the first axis, and the first continuous reading zone and the second continuous reading zone partially overlap to form a third continuous reading zone.

3. The first magnetic field and the second magnetic field are directed in opposite directions. The RFID reader system according to claim 1, characterized in that the sum of the first magnetic field and the second magnetic field is substantially zero in the far field.

4. The first loop configuration and the second loop configuration form a sequence of spaced antenna loops. The RFID reader system according to claim 2, characterized in that the spaced antenna loops generate a reading zone with substantially uniform magnetic field strength.

5. The first loop is of a different size than the second loop. The RFID reader system according to claim 4, characterized in that the first inner region is substantially the same as the second inner region.

6. The RFID reader system according to claim 4, characterized in that the sequence includes a non-even number of antenna loops.

7. The RFID reader system according to claim 4, characterized in that the sequence has a figure-eight shape with two antenna loops having substantially the same inner area.

8. The first series includes two overlapping figure-eight shaped antenna coils, The second series includes two overlapping figure-eight shaped antenna coils, The first continuous reading zone is associated with the first container section and the second container section, The second continuous reading zone is associated with the second container section and the third container section, The RFID reader system according to claim 7, characterized in that the third continuous reading zone is associated with the second container section.

9. The RFID reader system according to claim 1, characterized in that the sum of the first magnetic field and the second magnetic field becomes substantially zero in the far field due to the number of loops and the inner area of ​​the loops.

10. The RFID reader system according to claim 1, characterized in that each of the continuous reading zones includes a series of interleaved reading zones generated by the antenna coil.

11. The RFID reader system according to claim 1, characterized in that the continuous reading zone has a magnetic field direction for detecting an electronic tag in a predetermined upright direction.

12. The antenna controller activates each of the antenna coils at multiple power levels, The aforementioned processor, Receiving multiple response signals associated with each of the multiple power levels, The RFID reader system according to claim 1, characterized in that it determines the height level of the container based on the plurality of received response signals.

13. A method for determining the location of electronically tagged items within a container section of a container using an RFID reader, and for reducing the magnetic field in the far field, The steps include providing each antenna coil of a set of overlapping antenna coils that form a continuous reading zone individually associated with the container section, The steps include receiving a plurality of response signals associated with an activated combination of antenna coils from the aforementioned set of antenna coils, Steps include identifying a reading zone that responds to a combination of activated antenna coils, Based on the identified reading zone, the step of identifying the container section as the location of the article, The step of individually activating the antenna coils in order to locate the electronically tagged article, The aforementioned set of overlapping antenna coils is The antenna coil comprises a first loop configuration and a second loop configuration electrically connected to the first loop configuration. The first loop configuration includes a first loop having a first current that induces a first magnetic field for detecting an electronic tag in the near field. The second loop configuration includes a second loop having a second current whose rotational direction is opposite to that of the first current. The second current induces a second magnetic field for detecting an electronic tag in the near field. The first loop configuration has a first inner region, The second loop configuration has a second inner region, As a result, the first magnetic field reduces the second magnetic field in the far field. The aforementioned set of overlapping antenna coils includes a series of antenna coils that overlap laterally, The series of antenna coils are aligned along the length of the container section, The method is characterized in that the set of overlapping antenna coils is arranged across multiple sections.

14. The step of individually activating each of the aforementioned antenna coils includes the step of operating each of the aforementioned antenna coils with a plurality of different powers, The step of receiving the plurality of response signals includes the step of receiving a response signal associated with each of the antenna coils with respect to each of the plurality of different powers, The method according to 13, wherein the step of identifying the container section includes the step of determining the height level of the container in response to the plurality of response signals.

15. The RFID reader system according to claim 1, characterized in that the first loop arrangement and the second loop arrangement are substantially coplanar.

16. The RFID reader system according to claim 4, characterized in that the sequence has a figure-eight shape with two antenna loops having substantially the same inner area.

17. The RFID reader system according to claim 4, characterized in that the sequence includes a non-even number of antenna loops.

18. The first loop is of a different size than the second loop. The RFID reader system according to claim 1, characterized in that the first inner region is substantially the same as the second inner region.

Images