Patent Application
20230352846
Some radio frequency identification (RFID) systems operate in accordance with an effective isotropic radiated power (EIRP) limit and, thus, may have a limited effective range over which RFID tags can be read. This may be particularly problematic when RFID tags are disposed on objects in positions that are difficult to read via the RFID system.
In an embodiment, a radio frequency (RF) reflector for use with a radio frequency identification (RFID) system comprises a four-sided housing. The four-sided housing including: an open end configured to admit RF signals emitted by a RF identification (RFID) tag reader into the RF reflector, wherein a dimension of the open end is greater than a quarter wavelength of the RF signals, and wherein the RF reflector is configured to not be electrically coupled to the RFID tag reader; an end comprising a material that at least partially reflects the RF signals; two sides comprising a material that at least partially reflects the RF signals, wherein the end, the two sides, and the top are electrically connected; a top comprising a material that at least partially reflects the RF signals; and an open bottom.
In a variation of this embodiment, the RF reflector is configured to be placed on a work surface during use such that the open bottom is adjacent the work surface, and the top includes one or more top openings configured to admit at least a portion of objects having RFID tags into the RF reflector such that the RFID tags can be read by the RFID tag reader responsive to the RF signals, wherein at least one of the one or more top openings is positioned at a distance from the open end that is greater than a native effective range of the RFID tag reader, and wherein a dimension of the one or more top openings is greater than a quarter wavelength of the RF signals.
In a variation of this embodiment, the objects in the one or more top openings can rest on the work surface.
In a variation of this embodiment, the RF reflector is configured to be inverted during use such that the top becomes a bottom, such that the end and the two sides extend upward from the bottom and upward from the work surface, and one or more objects having RFID tags can be placed on the bottom such that the RFID tags can be read by the RFID tag reader responsive to the RF signals, and the RF reflector is configured such that the RFID tags can be read by the RFID tag reader from distances greater than a native effective range of the RFID tag reader.
In a variation of this embodiment, when the RF reflector is in use, the bottom at least one of (i) is adjacent to the work surface, (ii) is at least partially separated from the work surface by an air gap, or (iii) includes an electrically non-conductive layer to electrically isolate the bottom from the work surface.
In a variation of this embodiment, the four-sided housing is configured as a passive resonator.
In a variation of this embodiment, parasitic capacitances form on the end, the two sides, and the top responsive to the RF signals, wherein the parasitic capacitances form transmission paths for the RF signals.
In a variation of this embodiment, the end, the two sides, and the top are configured to re-radiate RF signals into the RF reflector with different phases.
In a variation of this embodiment, the RF reflector is configured to increase an effective range of the RFID tag reader.
In another embodiment, a radio frequency (RF) reflector for use with a radio frequency identification (RFID) system comprises a five-sided housing. The five-sided housing including: a bottom comprising a material that at least partially reflects RF signals; and first, second, and third sides comprising a material that at least partially reflects the RF signals, wherein the bottom and the first, second, and third sides are electrically connected; a fourth side having a side opening, the side opening configured to admit the RF signals emitted by a RF identification (RFID) tag reader into the RF reflector, wherein a dimension of the side opening is greater than a quarter wavelength of the RF signals, and wherein the RF reflector is configured to not be electrically coupled to the RFID tag reader; and an open top.
In a variation of this embodiment, the fourth side comprises a material that at least partially reflects RF signals, and wherein the fourth side is electrically connected to the bottom and the first, second, and third sides.
In a variation of this embodiment, (i) the RF reflector is configured to be inverted during use such that the bottom becomes a top, (ii) when the RF reflector is placed on a work surface, the open top is adjacent the work surface, and (iii) the top includes one or more top openings configured to admit at least a portion of objects having RFID tags into the RF reflector such that the RFID tags can be read by the RFID tag reader responsive to the RF signals, wherein at least one of the one or more top openings is positioned at a distance from the side opening that is greater than a native effective range of the RFID tag reader, and wherein a dimension of the one or more top openings is greater than a quarter wavelength of the RF signals.
In a variation of this embodiment, the objects in the one or more top openings can rest on the work surface.
In a variation of this embodiment, the RF reflector is configured to be placed on a work during use such that the end and the first, second, and third sides extend upward from the bottom and upward from the work surface, and one or more objects having RFID tags can be placed on the bottom such that the RFID tags can be read by the RFID tag reader responsive to the RF signals, and wherein the RF reflector is configured such that the RFID tags can be read by the RFID tag reader from distances greater than a native effective range of the RFID tag reader.
In a variation of this embodiment, the bottom includes an electrically non-conductive layer to electrically isolate the RFID tags from the bottom.
In a variation of this embodiment, the five-sided housing is configured as a passive resonator.
In a variation of this embodiment, parasitic capacitances form on the bottom and the first, second, and third sides responsive to the RF signals, wherein the parasitic capacitances form a transmission path for the RF signals.
In a variation of this embodiment, the bottom and the first, second, and third sides are configured to re-radiate RF signals into the RF reflector with different phases.
In a variation of this embodiment, the RF reflector is configured to increase an effective range of the RFID tag reader.
In yet another embodiment, a radio frequency (RF) reflector for use with a radio frequency identification (RFID) system includes a first layer comprising a material that at least partially reflects RF signals, wherein the RF reflector is configured to not be electrically coupled to an RFID tag reader used to read RFID tags positioned above the RF reflector; and a second, electrically non-conductive layer to electrically isolate RFID tags from the first layer, wherein the RF reflector is configured to be placed on a work surface during use.
In a variation of this embodiment, when the RF reflector is in use, the first layer at least one of (i) is adjacent to the work surface, (ii) is at least partially separated from the work surface by an air gap, or (iii) includes a third, electrically non-conductive layer to electrically isolate the first layer from the work surface.
The accompanying figures, where like reference numerals refer to identical or functionally similar elements throughout the separate views, together with the detailed description below, are incorporated in and form part of the specification, and serve to further illustrate embodiments of concepts that include the claimed invention, and explain various principles and advantages of those embodiments.
Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of embodiments of the present invention.
The apparatus and method components have been represented where appropriate by conventional symbols in the drawings, showing only those specific details that are pertinent to understanding the embodiments of the present invention so as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein.
Use of terms such as up, down, top, bottom, side, end, front, back, etc. are used herein with reference to a currently considered or illustrated orientation. If such elements are considered with respect to another orientation, it should be understood that such terms should be correspondingly modified.
In some circumstances, having to move RFID tags and/or RFID tag readers near to each other so that the RFID tags can be interrogated and read may be inconvenient and/or impractical. In addition to distance limitations due to EIRP or other constraints, the performance of conventional RFID systems may be further limited due to RFID tag location, RFID tag orientation, RFID tag size, RF attenuating or absorptive substances or materials, etc. For example, RFID tags may be located on the bottom of objects (e.g., coffee cups) in a retail environment such that when an object is placed on a work surface during checkout, an edge of an affixed RFID tag may be oriented towards an RFID tag reader, such that the RFID tag reader is effectively located in an RFID null of the RFID tag. Moreover, an RFID tag may be located at, or in, a null of the far field resulting from RF signals emitted by an RFID tag reader. Further, when objects are small, the size of an RFID tag may be limited, thus, further restricting the performance of an RFID system used to interrogate and read the RFID tag. Furthermore, the work surface may be made of a material (e.g., metal) that may effectively short out an RFID tag. Even further, an object may contain a liquid or other substance (e.g., coffee, water, tea, etc.) that may absorb or attenuate RF signals emitted by the RFID tag reader. Such circumstances represent the native working range or conditions of the RFID tag reader. In some circumstances, simply using stronger RF signals may still not result in RFID tags being reliably readable. Moreover, it may not be practical or desirable to have to position RFID tags closer to an RFID tag reader, or in particular orientations, such that the RFID tags are reliably readable. Accordingly, there is a need for an RF reflector that can be used with a conventional RFID tag reader to increase an effective RFID working range or conditions of the RFID tag reader without requiring use of a higher EIRP or modification of the RFID tag reader. The effective working range or conditions of an RFID tag reader represents the areas, directions, distances, etc. in which RFID tags of various sizes in various positions, orientations, etc. can be reliably interrogated and read by the RFID tag reader regardless of the type(s) of objects to which RFID tags may be affixed that results from use of the RFID tag reader with disclosed RF reflectors. Thus, the effective working range of an RFID tag reader resulting from use of disclosed RF reflectors is improved or increased relative to the native working range of the RFID tag reader.
Reference will now be made in detail to non-limiting examples, some of which are illustrated in the accompanying drawings.
The example RF reflector 100 has an open bottom 110 and an open end 112. As shown, the RF reflector 100 can be used by setting the RF reflector 100 on a work surface 114 (e.g., a counter) such that the open bottom 110 is adjacent the work surface 114; and the sides 104 and 106, and the end 108 extend upwardly from the work surface 114 toward the top 102. In use, an RFID tag reader 116 can be positioned in front of the open end 112 such that RF signals 118 emitted by an antenna (not shown for clarity of illustration) of the RFID tag reader 116 are admitted through the open end 112 into the RF reflector 100. One or more dimensions of the open end 112 may be larger than one-fourth the wavelength of the RF signals 118 (e.g., a quarter wavelength) to allow the RF signals 118 to propagate through the open end 112. In some examples, the RF reflector 100 is configured to not be electrically coupled to the RFID tag reader 116.
At least because (i) the open bottom 110 and the open end 112 are open; (ii) the antenna of the RFID tag reader 116 does not form a feed network for the RF reflector 100; and (iii) the open end 112 is configured to not form a waveguide port, the RF reflector 100 advantageously does not form a waveguide. Instead, the RF reflector 100 forms a passive RF resonator, and/or a parasitic reflector assembly. The RF signals 118 emitted by the RFID tag reader 116 are capacitively or inductively launched into the RF reflector 100 through the open end 112, and travel along the RF reflector 100 from the open end 112 toward the end 108, and reflect off the top 102 and the sides 104 and 106. The end 108, which is electrically coupled to the top 102 and the sides 104 and 106, provides a return path for reflected RF signals. Accordingly, RF signals propagate inside the RF reflector 100 in various different directions. The top 102, the sides 104 and 106, and the end 108 act as passive resonators that reflect and/or re-radiate the RF signals with different phases. As such, parasitic capacitances and/or surface currents can form on the top 102, the sides 104 and 106, and the end 108 responsive to RF signals that form transmission paths for the RF signals. The different RF signals constructively interfere to strengthen RF signals in a desired direction along the RF reflector 100 such that directivity in the desired direction is increased, and destructively interfere to cancel out RF signals in other non-desired directions.
The top 102 includes a top opening 120 defined therein, in which an object (e.g., a cup 122) can at least partially be placed, such that an affixed RFID tag 124 can be interrogated and read using RF signals propagating throughout the RF reflector 100. As shown, an object (e.g., the cup 122) may rest on the work surface 114. Unlike a waveguide, the bottom 110 of the RF reflector 100 is open, such that the RFID tag 124 is may be prevented from being shorted out by an electrically conductive bottom that is typically included in waveguides. Moreover, as described below in connection with
As shown in
In some examples, the RFID tag reader 116 and RFID tag 124 utilize ultra-high frequency RF signals (e.g., using a carrier frequency of 915 MHz). In some examples, the RFID tag reader 116 and the RFID tag 124 are implemented in accordance with a communication interface guideline or standard defined by the RAIN™ Alliance.
As shown, the RF reflector 500 can be used by setting the RF reflector 500 on a work surface 114 such that the bottom 502 is adjacent to, or against, a work surface 114; and the sides 104 and 106, and the end 108 extend upwardly from the bottom 502 and upwardly toward an open top 504. In use, the RFID tag reader 116 can be positioned in front of the open end 112 such that RF signals 118 emitted by an antenna (not shown for clarity of illustration) of the RFID tag reader 116 are admitted into the RF reflector 500. Like the RF reflector 100, one or more dimensions of the open end 112 of the RF reflector 500 may be larger than one-fourth the wavelength of the RF signals 118 (e.g., a quarter wavelength) emitted by the RFID tag reader 116 to allow the RF signals 118 to propagate through the open end 112.
At least because (i) the open top 504 and the open end 112 are open; (ii) the antenna of the RFID tag reader 116 does not form a feed network for the RF reflector 500; and (iii) the open end 112 is configured to not form a waveguide port, the RF reflector 500 does not form a waveguide. Instead, the RF reflector 500 forms a passive resonator and/or a parasitic reflector assembly. Like the RF reflector 100, the RF signals 118 emitted by the RFID tag reader 116 are capacitively or inductively launched into the RF reflector 500 through the open end 112, and travel along the RF reflector 500 from the open end 112 toward the end 108, and reflect off the bottom 502 and the sides 104 and 106. The end 108, which is electrically coupled to the bottom 502 and the sides 104 and 106, provides a return path for reflected RF signals. Accordingly, as described below in connection with
As shown, objects (e.g., a cup 122) having respective RFID tags (e.g., an RFID tag 124) affixed thereto may be at least partially placed in, or on, the RF reflector 500, such that the RFID tags can be interrogated and read by the RFID tag reader 116. Because, as described below in connection with
The configuration of
Because RF signals can propagate across the RF reflector 900, RFID tags can be interrogated and read at greater distances from the RFID tag reader 116 without having to modify the RFID tag reader 116, and/or without having to increase the EIRP of the RFID tag reader 116. That is, RFID tags can be interrogated and read by the RFID tag reader 116 within an area that is larger than or outside the native effective range or conditions of the RFID tag reader 116 when the RF reflector 900 is not used. In other words, the RF reflector 900 can increase the working range or conditions of the RFID tag reader 116. For example, the RF reflector 900 can extend across a counter area of a retail point-of-sale, allowing the RFID tag reader 116 to be positioned near an employee or cash register on one side of a counter, while a shopper can easily place the cup 122 into the RF reflector 900 nearer to them on an opposite side of the counter.
As described above in connection with
While example RF reflectors having four or five sides are shown and described herein, RF reflectors having fewer or more sides are envisioned and may be implemented. For instance, another example RF reflector is a simple reflective mat or surface with a non-conductive layer on its top to electrically isolate RFID tags from the mat or surface.
The above description refers to aspects of the accompanying drawings. Alternative implementations of the examples represented by the diagrams include one or more additional or alternative elements. Additionally or alternatively, one or more of the elements of the diagrams may be combined, divided, re-arranged, or omitted.
In the foregoing specification, specific embodiments have been described. However, one of ordinary skill in the art appreciates that various modifications and changes can be made without departing from the scope of the invention as set forth in the claims below. Accordingly, the specification and figures are to be regarded in an illustrative rather than a restrictive sense, and all such modifications are intended to be included within the scope of present teachings. Additionally, the described embodiments/examples/implementations should not be interpreted as mutually exclusive, and should instead be understood as potentially combinable if such combinations are permissive in any way. In other words, any feature disclosed in any of the aforementioned embodiments/examples/implementations may be included in any of the other aforementioned embodiments/examples/implementations.
The benefits, advantages, solutions to problems, and any element(s) that may cause any benefit, advantage, or solution to occur or become more pronounced are not to be construed as a critical, required, or essential features or elements of any or all the claims. The claimed invention is defined solely by the appended claims including any amendments made during the pendency of this application and all equivalents of those claims as issued.
Moreover in this document, relational terms such as first and second, top and bottom, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. The terms “comprises,” “comprising,” “has”, “having,” “includes”, “including,” “contains”, “containing” or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises, has, includes, contains a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. An element proceeded by “comprises ...a”, “has ...a”, “includes ...a”, “contains ...a” does not, without more constraints, preclude the existence of additional identical elements in the process, method, article, or apparatus that comprises, has, includes, contains the element. The terms “a” and “an” are defined as one or more unless explicitly stated otherwise herein. The terms “substantially”, “essentially”, “approximately”, “about” or any other version thereof, are defined as being close to as understood by one of ordinary skill in the art, and in one non-limiting embodiment the term is defined to be within 10%, in another embodiment within 5%, in another embodiment within 1% and in another embodiment within 0.5%. The term “coupled” as used herein is defined as connected, although not necessarily directly and not necessarily mechanically. A device or structure that is “configured” in a certain way is configured in at least that way, but may also be configured in ways that are not listed.
Further, unless expressly stated to the contrary, “or” refers to an inclusive or and not to an exclusive or. For example, “A, B or C” refers to any combination or subset of A, B, C such as (1) A alone, (2) B alone, (3) C alone, (4) A with B, (5) A with C, (6) B with C, and (7) A with B and with C. As used herein, the phrase “at least one of A and B” is intended to refer to any combination or subset of A and B such as (1) at least one A, (2) at least one B, and (3) at least one A and at least one B. Similarly, the phrase “at least one of A or B” is intended to refer to any combination or subset of A and B such as (1) at least one A, (2) at least one B, and (3) at least one A and at least one B
The Abstract of the Disclosure is provided to allow the reader to quickly ascertain the nature of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. In addition, in the foregoing Detailed Description, it can be seen that various features are grouped together in various embodiments for the purpose of streamlining the disclosure. This method of disclosure is not to be interpreted as reflecting an intention that the claimed embodiments require more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive subject matter may lie in less than all features of a single disclosed embodiment. Thus, the following claims are hereby incorporated into the Detailed Description, with each claim standing on its own as a separately claimed subject matter.
