Patent Application
20070080804
Embodiments of the present invention relate generally to radio frequency identification (RFID) tag performance and, more specifically, to systems and methods of enhancing the radio frequency identification of objects, such as containers.
Radio frequency identification (RFID) tags are small integrated circuits which are attached to containers, packages, or individual goods. They are used to store information about the item such as price, serial number, and shipping information (including tracking number, shipping date, arrival date, as well as other information). RFID tags are read using an RFID receiver or reader which transmits a radio frequency interrogation signal to the tags. The tag detects the reader interrogation signal and replies by transmitting a response signal that contains the information stored in the RFID tag. The RFID reader detects the response signal from the RFID tag and stores the information in its memory. Some RFID tags contain a battery, while others store the energy of the received interrogation signal and use that energy to power their circuits.
Environmental, material, and electromagnetic conditions all affect the performance of RFID tags. Different physical mechanisms that affect the propagation of electromagnetic or radio waves include reflection or scattering, re-radiation, shielding, absorption, and spreading loss. In a space free of any obstructions or absorption mechanisms, the strength of a radio frequency signal declines in inverse proportion to the square of the distance. For an electromagnetic wave propagating through a region in which signal modifications can arise from the ground and from obstacles (particularly conductors, such as metal or liquid obstacles), the reduction in strength over distance is greater and the signal path can vary considerably. The disruptive materials may be the goods within their packaging, the surface of the goods themselves, or the walls of the exterior container.
As a result, a reader interrogation signal is often redirected and attenuated before it actually reaches the RFID tag. And, similarly, the response signal from the RFID tag is often redirected and attenuated before it actually reaches the reader. This means that the contents of the container as well as the composition of the container can strongly influence whether 100% tag readability can be achieved in practice. In a radio frequency identification system, 100% tag readability means that all RFID tags representing their respective tagged items are identified and “counted” through data transfer with a reader.
Some advancements have been made to enhance RFID tag readability, such as optimizing the placement of RFID tags on containers or increasing the time that the container is in the radio frequency reader field to allow sufficient time for resolution of signal overlaps, signal averaging, or greater power accumulation in the RFID tag. These advancements, however, fail to accommodate all attenuation, particularly electromagnetic wave absorption.
Therefore, there exists a need to enhance radio frequency transmission in response to environmental influences, both internal and external, on the range of transmission. Such technology would have immediate value in the packaging, shipping, and retail industries.
In accordance with aspects of the present invention, a combination container and radio frequency identification system is provided. The system includes at least one container having a container body. A radio frequency identification tag is associated with at least one container body, wherein the radio frequency identification tag is capable of transmitting a radio frequency signal. At least one discrete radio frequency device is associated with the radio frequency identification tag or at least one container body for enhancing readability of the radio frequency signal.
In accordance with other aspects of the present invention, a method of increasing readability of a radio frequency identification tag is provided. The method includes obtaining a container and associating at least one radio frequency identification tag with the container, wherein at least one radio frequency identification tag is capable of transmitting a radio frequency signal. The method further includes associating at least one radio frequency device with the radio frequency identification tag or the container, wherein at least one radio frequency device enhances readability of the radio frequency signal.
In accordance with other aspects of the present invention, another method of enhancing readability of a radio frequency identification tag is provided. The method includes receiving the interrogation signal transmitted from the reader or receiving the response signal transmitted from the radio frequency identification tag. The method further includes enhancing the received interrogation signal to enable readability by the radio frequency identification tag or enhancing the received response signal to enable readability by the reader.
The foregoing aspects and many of the attendant advantages of this invention will become more readily appreciated by reference to the following detailed description, when taken in conjunction with the accompanying drawings, wherein:
Embodiments of the present invention are directed to systems and methods for enhancing radio frequency identification of at least one object, such as a container. A combination container and radio frequency identification system 20 constructed in accordance with one embodiment of the present invention may be best understood by referring to
In one embodiment, the container 22 includes a body of substantially electrically non-conductive material, such as paper, cardboard, paperboard, corrugated paperboard, fiberform, or like cellulosic materials. For example, in the illustrated embodiment of
Although the container 22 in the illustrated embodiment is manufactured from corrugated paperboard, it will be appreciated that other containers made from other materials are also within the scope of the invention. As non-limiting examples, the container may be formed from metals (such as foils), wood, plastics (such as shrink wrap or pouch-packets), glass, or any other materials or combinations thereof. Also as non-limiting examples, the container may include a body of substantially electrically conductive material or a body of non-conductive material. In addition, the container may be of another three-dimensional shape besides substantially cubic shape. As non-limiting examples, the container may be rectangular, prismatic, cylindrical, or any other three-dimensional shape. As will be discussed in greater detail below, varying container materials result in varying radio frequency signal attenuation due to material absorption and/or reflection. Therefore, container material should be considered a contributing factor in the design of a sufficient radio frequency enhancement system.
While
In embodiments of the present invention, the RFID tags may be, for example, positioned on the external surface of the container body, inside the container body, or affixed to goods (which may also be containers, such as cans of soup, boxes of laundry detergent, reams of paper, lumber, electronics, etc.) inside the container body. Returning to
The RFID tag 24 may be categorized as either active or passive, both of which may be practiced with embodiments of the present invention. Active RFID tags are powered by an internal battery and are typically read/write, which means that tag data can be read as well as rewritten and/or modified. An active tag's memory size varies according to application requirements; some systems operate with up to 1 MB of memory. In a typical read/write RFID system, an RFID tag contains associated identification and content data in the form of encoded data. The RFID tag can also receive information from a reader in the form of encoded data. This encoded data then becomes part of the history of the tagged container or good. The battery-supplied power of an active RFID tag generally gives it a greater radio frequency receiving and outputting range. Trade-offs for active RFID tags, however, include greater size, greater cost, and limited operational life.
Passive RFID tags, on the other hand, operate without a separate external power source and obtain their operating power as it is generated from the reader. Passive RFID tags are consequently much lighter and less expensive than active tags, and they offer a virtually unlimited operational lifetime. The trade-offs for passive RFID tags include shorter radio frequency receiving and outputting ranges than active RFID tags, requiring a higher-powered reader.
Whether the RFID tag 24 is active or passive, the RFID tag 24 is capable of receiving a radio frequency signal and outputting content or identification data that is stored in its memory as a radio frequency signal. As will be described in detail below, the RFID tag 24 is capable of receiving interrogation signals from the reader 28 (or the repeater 26), and based on the received interrogation signal, generates and transmits a radio frequency signal carrying content and identification data. Because RFID tags that are capable of receiving a signal and outputting content or identification data as a signal are well known in the art, a further description of RFID tags will not be contained herein. However, it will be appreciated that any conventional or future-developed RFID tags that are capable of receiving a radio frequency signal and outputting content or identification data as a radio frequency signal, including the inductance and capacitance type, may be practiced with embodiments of the present invention.
It will be appreciated that the consideration of whether a passive or active RFID tag is employed in a radio frequency identification system 20 is part of the calculus of optimizing or enhancing the accuracy of the system. The transmission of signals between the reader, the RFID tag (whether passive and active), and the repeater, as well as system optimization, will be discussed in greater detail below.
As was discussed above, the RFID tag 24 is read by a radio frequency reader 28. The reader 28 may be any conventional RFID tag reader 28 known in the art and thus will not be described in any more detail. The radio frequency reader 28 shown in
When an RFID tag 24 passes through or is located within the reader communication field, the RFID tag detects a reader interrogation signal and responds by transmitting a modulated radio frequency signal carrying content or identification data associated therewith. The content and identification data carried by the radio frequency signal typically corresponds to the container that is associated with the RFID tag and includes information such as destination information, model and serial numbers, customer numbers, instructions for handling, etc. The reader then detects the response signal transmitted by the RFID tag by its associated antenna and decodes or demodulates the response signal to obtain the associated content or identification data, as known in the art. The content or identification data may then be passed to a host computer for processing, as known in the art.
Sometimes the RFID tag cannot receive the interrogation signal or the interrogation signal is too weak to cause the RFID tag to generate and transmit its identity and content data. Thus, accurate and reliable detection of RFID tags is an ongoing problem in conventional RFID systems. Accurate and reliable detection of RFID tags is made difficult by a number of factors including, for example, the following: (a) RFID tags have a limited amount of power available to operate for responding to a signal transmission from a reader; (b) RFID tags with undersized antennas frequently cannot pick up interrogation signals transmitted by a reader; (c) readers have output strength limitations set by national governmental organizations (for example, by the U.S. Federal Communications Commission) for safety reasons; (d) the orientation of the RFID tags may be unsuitable for absorbing sufficient power from the signal transmitted by the reader; (e) the orientation of the RFID tags may be unsuitable for providing a transmitted signal sufficient for accurate reception by the reader; (f) cooperation of the RFID tags with the reader may require sophisticated logic in the transceiver to accurately perform the RFID tag portion of a communication protocol used to obtain an open communication channel between the reader and a single RFID tag; (g) multiple RFID tags transmitting simultaneously may cause a so-called radio frequency signal “collision”; (h) environment conditions, such as ice, rain-water, condensation, and humidity affect signal transmission; and (i) environmental “noise” causes interference with the interrogation and response signals.
Factors (c), (d), (e), (f), (g), (h), and (i) identified above are generally associated with signal strength, orientation, and simultaneous transmission, and thus, the loss path or signal attenuation of the reader interrogation signals or the RFID tag response signals. Factors (a) and (b) are generally associated with RFID tag limitations for receiving and responding to a reader interrogation signal. An exemplary loss path is illustrated in
The response signal 444T is subject to similar limitations and attenuation factors that the reader interrogation signal 440R is subject to. However, reader antennas in general may be larger than the RFID tag antennas, thus having stronger reception capabilities and enabling detection of attenuated signals. In this regard, the reader antenna 432 may be able to detect and receive attenuated response signals 444T transmitted from the RFID tag 424 much more readily than the RFID tag 424 is able to detect and receive attenuated interrogation signals 440R transmitted from the reader 428. Thus, if the RFID tag 424 response signal 444T has sufficient signal strength to be detected by the reader antenna 432, the response signal 444T carrying content and identification data is, in turn, received by the reader 428.
To address, or potentially mitigate, the low signal strength and signal attenuation factors (c), (d), (e), (f), (g), (h), and (i), the RFID tag limitations (a) and (b), as well as other factors, in accordance with aspects of the present invention, the system 20 may include at least one radio frequency device 26 for enhancing the readability of the radio frequency signal, as best shown in
As seen in
Turning now to
The repeater 1026 is generally associated with the RFID tag 1024 to receive the interrogation signal 1040R from the reader 1028 and to retransmit (or reradiate) signal 1040R as signal 1040RX at an appropriate retransmission strength and in multiple directions. Specifically, these “multiple directions” may include directions other than the direction of the propagation of the signal (for example, signals 1040R or 1044T) received by the repeater 1026. Likewise, the repeater 1026 may receive the response signal 1044T from the RFID tag 1024 and retransmit (or reradiate) signal 1044T as signal 1044TX at an appropriate retransmission strength and in multiple directions. As will be discussed in detail below, the repeater 1026 also may receive a radio frequency signal from another repeater (not shown) and retransmit (or reradiate) the repeater signal at an appropriate retransmission strength and in multiple directions. Thus, the repeater 1026 may be any conventional radio frequency repeater capable of, for example, receiving an interrogation signal 1040R from the reader 1028 and retransmitting (or reradiating) the received reader interrogation signal 1040R as signal 1040RX at an appropriate retransmission strength and in multiple directions and thus will not be described in any more detail. It will be appreciated that an appropriate retransmission strength will be dependent on the entire system, in addition to the transmission strength of the reader, and can vary according to the desired application.
In one embodiment, the radio frequency repeater 1026 may be an active radio frequency repeater, and thus, the received reader interrogation signal 1040R may be amplified prior to retransmission as repeated signal 1040RX. It will be appreciated that the frequency and timing of repeated signal 1040RX may be arranged to prevent self-oscillation by an active repeater or by a system of active repeaters if multiple active repeaters are used. It will also be appreciated that the active repeater may be of any known configuration, including conventional components known in the art.
In other embodiments, the radio frequency repeater 1026 may be passive. In such an embodiment, the passive repeater may include an antenna and a conventional tank or tuned circuit. In use, the tank circuit resonates once the reader interrogation signal 1040R is received from the antenna and reradiates the received reader interrogation signal 1040R as repeated signal 1040RX. In another embodiment, the passive repeater may include a signal reflecting apparatus, such as a metallic object or a system of metallic objects, such as pipes or wires. In use, the signal reflecting apparatus changes the direction of the electromagnetic radiation propagation direction by reflection to send the signal to a more useful location (e.g., into a stack of containers on a pallet to RFID tags located on goods housed within the containers, or out of the containers to the RFID reader).
Such embodiments enhance the readability of the RFID tag by either reflecting the interrogation signal, providing a more efficient signal pathway, or selectively distorting (i.e., changing) the wave form of the interrogation signal and, therefore, such embodiments are also within the scope of radio frequency devices of the present disclosure.
In several embodiments, it will be appreciated that the repeater 1026 may retransmit (or reradiate) the reader interrogation signal 1040R as repeater signal 1040RX over varying distances, for example, from 1 inch to 100 or more, as known in the art. Other distances, however, are within the scope of the present invention.
The repeater 1026 may be located in proximity to the RFID tag 1024 for enhancing the readability of the repeater signal 1040RX by the RFID tag 1024 and for enhancing the readability of the response RFID tag signal 1044T by the repeater 1026. Although the RFID tag 1024 and the repeater 1026 may be in proximity and in communication with one another, it will be appreciated that the repeater 1026 is a discrete component and, as such, is not physically attached to the RFID tag 1024 in the way that an antenna would be physically attached. Rather, the repeater 1026 and the RFID tag 1024 communicate via the transmission of, for example, signals 1040RX and 1044T. In addition, the repeater 1026 may be located in proximity to the reader 1028 for enhancing the readability of the reader signal 1040R by the repeater 1026 and for enhancing the readability of the repeater signal 1044TX by the reader 1028. Moreover, the repeater 1026 may be located in proximity to any other intermediate repeater for enhancing the readability of signals between intermediate repeaters (not shown).
In the illustrated embodiment of
The term “in proximity” is defined herein as located at a distance, considering system limitations and signal attenuation factors including absorption and reflection, such that the transmitted signal from the reader or the repeater reaches the RFID tag, and vice-versa. Hence, when the repeater is “in proximity” to the RFID tag, the reader, or another repeater, it may be located on the container, in the container, on another container, on a pallet supporting the container, next to the container, on the reader, near the reader, within the reader system, near another repeater, or in any other location in which a signal is capable of transmitting between the repeater and the RFID tag, between the repeater and the reader, or between any two intermediate repeaters, considering distance, RFID tag limitations, and signal attenuation factors.
Thus, the positioning of repeaters and the number of repeaters used within a system depends upon the reading environment, the physical make-up of the container, the number and orientation of the RFID tags to be read, the nature of the goods being contained, the limitations of the RFID tags, the strength of the reader, and the strength of the repeaters themselves. Such a repeater system can be optimized for enhanced readability based on these as well as other factors.
Referring now to
With reference to
In situations in which RFID tags are outside the reader communication field 1350, such as RFID tags 1324B as shown in
When RFID tags 1324B pass through or are located within the repeater communication field 1360, the RFID tags 1324B detect the repeater signal 1340RX (which is the retransmitted or reradiated reader interrogation signal 1340R) and respond by transmitting their own radio frequency signals 1344B carrying associated content and identification data. The reader 1328 (or in some cases, as will be discussed below, a repeater 1326) then detects the radio frequency signals 1344B transmitted from the RFID tags 1324B and decodes or demodulates the radio frequency signals 1344B to obtain the associated data.
As discussed above, reader antennas in general may have stronger signal reception capabilities than the RFID tag antennas, enabling them to more readily detect attenuated signals. Thus, in some circumstances, the response signals 1344B transmitted from the RFID tags 1324B may be received by the reader 1328 without the aid of a repeater 1326. However, in other circumstances in which the reader 1328 cannot read the radio frequency signals 1344B transmitted by the RFID tags 1324B, the repeaters 1326 may also repeat the radio frequency signals 1344B in much the same way as they repeat the reader interrogation signal 1340R as repeated signal 1340RX. That is, the repeaters 1326 detect the radio frequency signals 1344B of RFID tags 1324B and respond by retransmitting (or reradiating) the same radio frequency signals 1344BX, thereby extending the RFID tag communication field (not shown) such that these responsive signals 1344B may carry back to the reader 1328.
Although the repeaters 1326 in the illustrated embodiment of
With reference to
As discussed above, in some circumstances, the response signal 2044T transmitted from the RFID tag 2024 may be received by the reader 2028 without the aid of the repeaters 2026A and 2026B. However, in other circumstances in which the reader 2028 cannot read the radio frequency signals 2044 transmitted by the RFID tag 2024, the repeaters 2026A and 2026B may also repeat the RFID response signal 2044T in much the same way as they repeat the reader interrogation signal 2040R as repeated signals 2040RX and 2040RXX, as shown by arrows 2044TX and 2044TXX.
It will be appreciated that RFID tags and repeaters may be configured to apply conventional radio frequency techniques to prevent signal collision, such as responding to the reader interrogation signal at delayed or different time intervals. It is further contemplated that different operating frequencies may be used for different communication purposes, for example, an RFID tag may have a first circuit for receiving power (in the case of a passive RFID tag) and a second resonant circuit for reading or interrogation. In addition, a different operating frequency may be used for transmitting interrogation signals from the reader to the RFID tags than is used for transmitting response signals back from the RFID tags to the reader.
Now referring to
Spacing material within the scope of the present disclosure includes corrugated paperboard, organic or inorganic foams, paper, wood, and air, as well as any combinations thereof, or any other spacing material known or used in the art. Such spacing material is generally a low-density, non-conducting material providing minimal signal redirection and/or attenuation over distance beyond natural signal attenuation through dry air. Moreover, spacing material within the scope of the present enclosure may come in many forms, including panel-form, pallet-form, loose peanut-form, spray foam, form-fitted for specific goods, air bag form, or in any other dimension or form.
As seen in
In other embodiments, spacing material may be used in other locations other than being disposed within the container body. As non-limiting examples, spacing material may be used underneath containers (such as supporting or spacing pallets), between containers (such as spacing panels between a plurality of boxes), as liners on store shelving, or in other locations to enhance readability of radio frequency signals.
In another embodiment, spacing material may be used in conjunction with at least one active or passive repeater to further enhance signal communication and RFID tag performance. As seen in
Such repeater/spacing panels 780 can be disposable, or recoverable and re-useable in subsequent container 722 shipments. For example, the repeater/spacing panels 780 can be removed from the container 722 and reused in association with another container 722. As a non-limiting example, repeater/spacing panels 780 can be used in a shipment between multiple containers to enhance readability of radio frequency signals transmitted from RFID tags. After those RFID tags associated with those containers have been read or otherwise processed, the repeater/spacing panels 780 can be removed from their existing construction, and reused with a subsequent shipment of multiple containers.
The repeater/spacing panels 780 in the illustrated embodiment of
While several embodiments of the invention have been illustrated and described, it will be appreciated that various changes can be made therein without departing from the spirit and scope of the invention.
