Patent Application
20070152830
The use of radio frequency identification (RFID) technology is becoming increasingly widespread, largely due to the fact that the most common version of RFID tags can operate without an internal power source, instead using power scavenged from a received RF signal. However, this need for extremely low-power operation has limited the complexity and operational versatility of conventional RFID tags. In particular, the orientation of the antenna on an RFID tag can make a difference in whether the RFID tag is even detectable by the RFID reader.
Some embodiments of the invention may be understood by referring to the following description and accompanying drawings that are used to illustrate embodiments of the invention. In the drawings:
In the following description, numerous specific details are set forth. However, it is understood that embodiments of the invention may be practiced without these specific details. In other instances, well-known circuits, structures and techniques have not been shown in detail in order not to obscure an understanding of this description.
References to “one embodiment”, “an embodiment”, “example embodiment”, “various embodiments”, etc., indicate that the embodiment(s) of the invention so described may include particular features, structures, or characteristics, but not every embodiment necessarily includes the particular features, structures, or characteristics. Further, some embodiments may have some, all, or none of the features described for other embodiments.
In the following description and claims, the terms “coupled” and “connected,” along with their derivatives, may be used. It should be understood that these terms are not intended as synonyms for each other. Rather, in particular embodiments, “connected” may be used to indicate that two or more elements are in direct physical or electrical contact with each other. “Coupled” may mean that two or more elements co-operate or interact with each other, but they may or may not be in direct physical or electrical contact.
The term “processor” may refer to any device or portion of a device that processes electronic data from registers and/or memory to transform that electronic data into other electronic data that may be stored in registers and/or memory. A “computing platform” may comprise one or more processors.
An RFID reader may be used to transmit a signal to an RFID tag, and to receive the response signal transmitted by the RFID tag. Within the context of this document, an RFID tag may be defined as comprising at least one RFID antenna (to receive an incoming signal that serves to query the RFID tag and to transmit a response in the form of a modulated radio frequency signal), and an RFID tag circuit (which may include circuitry to store an identification code for the RFID tag, circuitry to transmit that code through the at least one antenna, and in some embodiments a power circuit to collect received energy from the incoming radio frequency signal and provide that energy to power the operations of the RFID tag circuit). As is known in the field of RFID technology, “transmitting” a signal from an RFID tag may, depending on the type of RFID tag, include either: 1) providing sufficient power to the antenna to generate a signal that radiates out from the antenna, or 2) reflecting a modulated version of the received signal. In some embodiments, the signal from the RFID reader may selectively address a particular RFID tag, so that only the selected tag will respond.
As used herein, unless otherwise specified the use of the ordinal adjectives “first”, “second”, “third”, etc., to describe a common object, merely indicate that different instances of like objects are being referred to, and are not intended to imply that the objects so described must be in a given sequence, either temporally, spatially, in ranking, or in any other manner.
Various embodiments of the invention may be implemented in one or any combination of hardware, firmware, and software. The invention may also be implemented as instructions contained in or on a machine-readable medium, which may be read and executed by one or more processors to perform the operations described herein. A machine-readable medium may include any mechanism for storing, transmitting, and/or receiving information in a form readable by a machine (e.g., a computer). For example, a machine-readable medium may include a storage medium, such as but not limited to read only memory (ROM); random access memory (RAM); magnetic disk storage media; optical storage media; a flash memory device, etc. A machine-readable medium may also include a tangible medium, which may include the aforementioned storage medium and/or a tangible device through which electrical, optical, acoustical or other form of propagated signals representing the instructions may pass, such as an antenna, optical fiber, communications interface, etc. A machine-readable medium may also include the propagated signal itself which has been modulated to encode the instructions.
Various embodiments of the invention may comprise use of two orthogonally polarized antennas on an RFID device. Polarization of the signals may be circular, or vertical/horizontal (where vertical/horizontal implies perpendicular with respect to each other—not necessarily vertical/horizontal with respect to gravity). This polarization may permit communication techniques such as but not limited to: 1) improve the signal-to-noise ratio (SNR) by transmitting and/or receiving the same signal on both antennas, 2) simultaneously transmitting or receiving different data on each antenna to increase overall data rate, 3) transmitting on one antenna while simultaneously receiving on another antenna for full duplex operation, 4) etc. ‘Simultaneously’ implies that at least a portion of the two actions takes place at the same time, although each action may have a different start and/or end time than the other action.
RFID reader 110 may also have another antenna 115. In some embodiments, antenna 115 may be used to transmit signals from the RFID reader to the RFID tag, while antennas 116 and 117 may be used to receive signals from the RFID tag. In the example of
Using the embodiment shown in
In some embodiments, the RFID reader may transmit a signal from antenna 218 that, due to relative polarization, is received by the RFID tag through antenna 226 but not through antenna 227. Similarly, the RFID reader may transmit a signal from antenna 219 that, due to relative polarization, is received by the RFID tag through antenna 227 but not through antenna 226. Thus, different signals may be transmitted separately and simultaneously from antennas 218 and 219, and those different signals may be received separately and simultaneously through antennas 226 and 227, respectively. Conversely, different signals may be transmitted separately and simultaneously from antennas 226 and 227, and those different signals may be received separately and simultaneously through antennas 216 and 217, respectively.
The resulting use of orthogonally polarized signals may effectively create two separate channels, which may be used in various ways, such as but not limited to the following:
The examples previously given assumed that both the RFID reader and the RFID tag included orthogonally polarized communications in the form of multiple antennas on both the reader and the tag. However, it is possible that in operation, an RFID reader may be expected to communicate both with RFID tags that have orthogonal polarization capability and RFID tags that do not. Further, those tags that do have such capability may be able to support only a limited set of the operations made possible by orthogonally polarized communications.
At 440 the RFID reader may interrogate the RFID tag that was singulated, requesting that tag to respond in a particular manner. In some embodiments, the response will include information that indicates whether the responding tag has the capability for orthogonally polarized communications. For example, a tag with such capability may place certain data in the response, while a tag without such capability would not. Alternatively, a tag with such capability may respond with orthogonally polarized signals, thus showing such capability without having to insert specific data in the response. Regardless of the method used to indicate such capability, processing may branch at 450 depending on the indication. If the tag does not indicate orthogonal polarization capability, the reader may proceed to communicate with the tag at 470 using standard RFID communication techniques. If the tag does indicate such capability, the reader may further determine at 460 which specific capabilities the tag has. In some embodiments, such determination may be made through a further query-response operation. In other embodiments, such determination may be made from the response to the interrogation at 440. Regardless of the technique used, the RFID reader may proceed to communicate with the RFID tag at 480, using the orthogonal polarization techniques that were indicated. Once the transaction is complete at 490, the operation may be terminated. Communication with another RFID tag may then be initiated (not shown).
The finished assembly of the container 530 with attached substrate 510 on two adjacent surfaces may be used to advantage on conveyer belts on which the containers pass by an RFID reader, such as RFID reader 550. Because the container will have three orthogonally-oriented antennas, as long as one of the container's surfaces is facing towards RFID reader 550, at least two antennas on the RFID tag may be oriented such that they may communicate with the reader with orthogonally polarized signals. The axis of the third antenna may be oriented such that it is not useful, but two antennas may be enough to implement the techniques previously described. Thus, a rectangular container may not have to be placed on the conveyer belt with any particular orientation for the dual antenna techniques to be used, as long as one surface of the container is approximately facing the orthogonally polarized RFID reader antennas 551 and 552.
If the containers are always oriented with a particular faces towards the RFID reader 550, then antenna 515, as well as the fold at 518, may be eliminated and the substrate 510 may be attached to that particular face of the container with the antennas 513 and 514 oriented vertically and horizontally, thus providing the correct polarization for the operations with RFID reader 550 previously described.
The foregoing description is intended to be illustrative and not limiting. Variations will occur to those of skill in the art. Those variations are intended to be included in the various embodiments of the invention, which are limited only by the spirit and scope of the following claims.
