Patent Application
20080030324
The accompanying drawings, which are incorporated herein and form a part of the specification, illustrate the present invention and, together with the description, further serve to explain the principles of the invention and to enable a person skilled in the pertinent art to make and use the invention.
The present invention will now be described with reference to the accompanying drawings. In the drawings, like reference numbers indicate identical or functionally similar elements. Additionally, the left-most digit(s) of a reference number identifies the drawing in which the reference number first appears.
Methods, systems, and apparatuses for RFID devices are described herein. In particular, methods, systems, and apparatuses for improved wireless data transfer using RFID systems are described.
The present specification discloses one or more embodiments that incorporate the features of the invention. The disclosed embodiment(s) merely exemplify the invention. The scope of the invention is not limited to the disclosed embodiment(s). The invention is defined by the claims appended hereto.
References in the specification to “one embodiment,” “an embodiment,” “an example embodiment,” etc., indicate that the embodiment described may include a particular feature, structure, or characteristic, but every embodiment may not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one skilled in the art to effect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described.
Before describing embodiments of the present invention in detail, it is helpful to describe an example RFID communications environment in which the invention may be implemented.
Environment 100 includes any number of one or more readers 104. For example, environment 100 includes a first reader 104a and a second reader 104b. Readers 104a and/or 104b may be requested by an external application to address the population of tags 120. Alternatively, reader 104a and/or reader 104b may have internal logic that initiates communication, or may have a trigger mechanism that an operator of a reader 104 uses to initiate communication. Readers 104a and 104b may also communicate with each other in a reader network.
As shown in
Various types of tags 102 may be present in tag population 120 that transmit one or more response signals 112 to an interrogating reader 104, including by alternatively reflecting and absorbing portions of signal 110 according to a time-based pattern or frequency. This technique for alternatively absorbing and reflecting signal 110 is referred to herein as backscatter modulation. Readers 104a and 104b receive and obtain data from response signals 112, such as an identification number of the responding tag 102. In the embodiments described herein, a reader may be capable of communicating with tags 102 according to any suitable communication protocol, including Class 0, Class 1, EPC Gen 2, other binary traversal protocols and slotted aloha protocols, any other protocols mentioned elsewhere herein, and future communication protocols.
Baseband processor 212 and network interface 216 are optionally present in reader 104. Baseband processor 212 may be present in reader 104, or may be located remote from reader 104. For example, in an embodiment, network interface 216 may be present in reader 104, to communicate between transceiver portion 220 and a remote server that includes baseband processor 212. When baseband processor 212 is present in reader 104, network interface 216 may be optionally present to communicate between baseband processor 212 and a remote server. In another embodiment, network interface 216 is not present in reader 104.
In an embodiment, reader 104 includes network interface 216 to interface reader 104 with a communications network 218. As shown in
Reader 104 has at least one antenna 202 for communicating with tags 102 and/or other readers 104. Antenna(s) 202 may be any type of reader antenna known to persons skilled in the relevant art(s), including a vertical, dipole, loop, Yagi-Uda, slot, or patch antenna type. For description of an example antenna suitable for reader 104, refer to U.S. Ser. No. 11/265,143, filed Nov. 3, 2005, titled “Low Return Loss Rugged RFID Antenna,” now pending, which is incorporated by reference herein in its entirety.
Transceiver 220 receives a tag response via antenna 202. Transceiver 220 outputs a decoded data signal 214 generated from the tag response. Network interface 216 is used to transmit decoded data signal 214 received from transceiver portion 220 (optionally through baseband processor 212) to a remote server coupled to communications network 218. Baseband processor 212 optionally processes the data of decoded data signal 214 prior to being sent over communications network 218.
In embodiments, network interface 216 enables a wired and/or wireless connection with communications network 218. For example, network interface 216 may enable a wireless local area network (WLAN) link (including a IEEE 802.11 WLAN standard link), a BLUETOOTH link, and/or other types of wireless communication links. Communications network 218 may be a local area network (LAN), a wide area network (WAN) (e.g., the Internet), and/or a personal area network (PAN).
In embodiments, a variety of mechanisms may be used to initiate an interrogation request by reader 104. For example, an interrogation request may be initiated by a remote computer system/server that communicates with reader 104 over communications network 218. Alternatively, reader 104 may include a finger-trigger mechanism, a keyboard, a graphical user interface (GUI), and/or a voice activated mechanism with which a user of reader 104 may interact to initiate an interrogation by reader 104.
In the example of
Modulator/encoder 208 receives interrogation request 210, and is coupled to an input of RF front-end 204. Modulator/encoder 208 encodes interrogation request 210 into a signal format, such as one of pulse-interval encoding (PIE), FM0, or Miller encoding formats, modulates the encoded signal, and outputs the modulated encoded interrogation signal to RF front-end 204.
RF front-end 204 may include one or more antenna matching elements, amplifiers, filters, an echo-cancellation unit, a down-converter, and/or an up-converter. RF front-end 204 receives a modulated encoded interrogation signal from modulator/encoder 208, up-converts (if necessary) the interrogation signal, and transmits the interrogation signal to antenna 202 to be radiated. Furthermore, RF front-end 204 receives a tag response signal through antenna 202 and down-converts (if necessary) the response signal to a frequency range amenable to further signal processing.
Demodulator/decoder 206 is coupled to an output of RF front-end 204, receiving a modulated tag response signal from RF front-end 204. In an EPC Gen 2 protocol environment, for example, the received modulated tag response signal may have been modulated according to amplitude shift keying (ASK) or phase shift keying (PSK) modulation techniques. Demodulator/decoder 206 demodulates the tag response signal. For example, the tag response signal may include backscattered data formatted according to FM0 or Miller encoding formats in an EPC Gen 2 embodiment. Demodulator/decoder 206 outputs decoded data signal 214.
The configuration of transceiver 220 shown in
Embodiments of the present invention are described in the following sections. These embodiments enable sensor data to be retrieved from sensors to be provided to tag, and to be read by readers.
Conventional RFID interrogators, such as reader 104, tend to strive to interrogate the highest volume of space allowable by the FCC. This results in the largest amount of RFID tags being interrogated at one time as possible. However, this leads to an inherent difficulty in determining which tag is which among the interrogated tag population. By limiting the read range to contact only, or to proximate range (e.g., in the range of inches or feet), as in near field transceiver 240, the uncertainty of volumetric interrogations is reduced or eliminated.
In antenna design, a near field is that part of the radiated field that is within a small number of wavelengths or one quarter of a wavelength of the diffracting edge or the antenna. Beyond the near field is the far field. Reader 104 typically utilizes a far field antenna 202.
Near field transceiver 240 is designed to incorporate similar functions as reader 104 while occupying a comparatively small area and having a much lower cost. Near field module 242 may incorporate circuits functionally similar to one or more of RF front end 204, modulator/encoder 208, demodulator 206, baseband processor 212 and network interface 216. Additionally, embodiments of the invention such as elements 502, 508 and 510 can operate on low power due to the relatively low amounts of power required for near field transmission as opposed to far field transmission. This results in a substantial energy savings when operating from for example, battery powered sources. In an embodiment, near field module 242 is implemented as part of an Integrated Circuit (IC) or an Application Specific Integrated Circuit (ASIC) of a sensor, as in sensor 400 in FIG. 4. Near field module 242 may be implemented as hardware, software, firmware or any combination thereof.
Near field transceiver 240 is typically much smaller than reader 104, although this is not necessary. As such, near field transceiver 240 can be incorporated in devices, mobile or stationary, to read tags in a near field fashion, such as in a “contact” or nearby fashion. For example, as shown in
The present invention is applicable to any type of RFID tag.
IC 306 controls operation of tag 102, and transmits signals to, and receives signals from RFID readers using antenna 304. In the example of
Memory 308 is typically a non-volatile memory, but can alternatively be a volatile memory, such as a DRAM. Memory 308 stores data 318 which includes an identification number. The identification number typically is a unique identifier (at least in a local environment) for tag 102. For instance, when tag 102 is interrogated by a reader (e.g., receives interrogation signal 110 shown in
Demodulator 314 is coupled to antenna 304 by antenna signal 328. Demodulator 314 demodulates a radio frequency communication signal (e.g., interrogation signal 110) on antenna signal 328 received from a reader by antenna 304. Control logic 310 receives demodulated data of the radio frequency communication signal from demodulator 314 on input signal 322. Control logic 310 controls the operation of RFID tag 102, based on internal logic, the information received from demodulator 314, and the contents of memory 308. For example, control logic 310 accesses memory 308 via a bus 320 to determine whether tag 102 is to transmit a logical “1” or a logical “0” (of identification number stored in data 318) in response to a reader interrogation. Control logic 310 outputs data to be transmitted to a reader (e.g., response signal 112) onto an output signal 324. Control logic 310 may include software, firmware, and/or hardware, or any combination thereof. For example, control logic 310 may include digital circuitry, such as logic gates, and may be configured as a state machine in an embodiment.
Modulator 316 is coupled to antenna 304 by antenna signal 328, and receives output signal 324 from control logic 310. Modulator 316 modulates data of output signal 324 (e.g., one or more bits of identification number 318) onto a radio frequency signal (e.g., a carrier signal transmitted by reader 104) received via antenna 304. The modulated radio frequency signal is response signal 112, which is received by reader 104. In an embodiment, modulator 316 includes a switch, such as a single pole, single throw (SPST) switch. The switch changes the return loss of antenna 304. The return loss may be changed in any of a variety of ways. For example, the RF voltage at antenna 304 when the switch is in an “on” state may be set lower than the RF voltage at antenna 304 when the switch is in an “off” state by a predetermined percentage (e.g., 30 percent). This may be accomplished by any of a variety of methods known to persons skilled in the relevant art(s).
Charge pump 312 (or other type of power generation module) is coupled to antenna 304 by antenna signal 328. Charge pump 312 receives a radio frequency communication signal (e.g., a carrier signal transmitted by reader 104) from antenna 304, and generates a direct current (DC) voltage level that is output on tag power signal 326. Tag power signal 326 is used to power circuits of IC die 306, including control logic 320.
Charge pump 312 rectifies the radio frequency communication signal of antenna signal 328 to create a voltage level. Furthermore, charge pump 312 increases the created voltage level to a level sufficient to power circuits of IC die 306. Charge pump 312 may also include a regulator to stabilize the voltage of tag power signal 326. Charge pump 312 may be configured in any suitable way known to persons skilled in the relevant art(s). For description of an example charge pump applicable to tag 102, refer to U.S. Pat. No. 6,734,797, titled “Identification Tag Utilizing Charge Pumps for Voltage Supply Generation and Data Recovery,” which is incorporated by reference herein in its entirety. Alternative circuits for generating power in a tag, as would be known to persons skilled in the relevant art(s), may be present. Further description of charge pump 312 is provided below.
It will be recognized by persons skilled in the relevant art(s) that tag 102 may include any number of modulators, demodulators, charge pumps, and antennas. Tag 102 may additionally include further elements, including an impedance matching network and/or other circuitry. Furthermore, although tag 102 is shown in
A sensor is typically a device having a sensing element that measures, detects or senses a signal or physical condition, such as motion, heat or light and converts the measured condition into an analog or digital representation. For example, an optical sensor detects the intensity or brightness of light, or the intensity of colors such as red, green and blue, and converts the measurement into an electrical signal for color systems. Sensors are heavily used in medicine, industry and robotics.
Most sensors are electrical or electronic, although other types exist. Types of sensors include but are not limited to motion sensors such as radar gun, speedometer, tachometer, odometer and turn coordinator; orientation sensors such as gyroscopes and ring laser gyroscopes; sound sensors such as microphones, hydrophones and seismometers; electromagnetic sensors such as ohmmeters and voltmeters; thermal energy sensors such as thermistors; mechanical sensors such as altimeters, gas meters acceleration sensors and position sensors; chemical sensors such as oxygen sensors and redox electrodes; ionizing sensors such as Geiger counters and scintillometers; non-ionizing sensors such as photocells and photodiodes. It is to be appreciated that sensors are not limited to examples presented above.
Embodiments of an improved RFID communication system are described in further detail below. Such embodiments interact with the tags described above, other tag types, near field transceivers and readers and/or may be used in alternative environments. Furthermore, the embodiments described herein may be adapted and modified, as would be apparent to persons skilled in the relevant art(s).
In step 602, a sensor collects data. For example, in an embodiment, a sensor detects a signal or physical condition, transduces the detected data into electrical signals or into a suitable format for storage. For instance, the sensor may be the sensor system 400 shown in
In optional step 604, the sensor transfers the data collected in step 602 to a near field transceiver. For example, in an embodiment the near field transceiver is near field transceiver 240. In one embodiment, the near field reader and the sensor are on the same PCB requiring transfer of data from the sensor memory to the near field transceiver memory (e.g., as shown in
In step 606, the near field transceiver formats the collected data, if required, according to an RFID protocol and transmits the formatted data to one or more tags using an RFID transmission protocol such as EPC Gen 2. In one embodiment, the near field transceiver transmits data to only one tag whose identification is pre-programmed in the near field transceiver. The tag is either in contact with the near field transceiver or proximate to the near field transceiver. In another embodiment, the near field transceiver interrogates tags in close proximity and transmits data to one or more responsive tags.
In step 608, a reader interrogates one or more tags for data. For example, in an embodiment, the reader is reader 104 shown in
In step 610, the tag or tags, in response to the interrogation in step 608, backscatter the data received from the near field transceiver in step 606.
In step 612, the reader receives the backscattered data from one or more tags.
In step 616, a sensor detects or senses a physical condition. The sensor may sense any type of condition, including but not limited to the types of conditions described above. The sensor may be programmed to sense a condition periodically or intermittently. In an embodiment, the sensor may sense data only on occurrence of a certain event or trigger. For example, a sensor may trigger and sense a physical condition based on movement or change in light, temperature or pressure conditions.
In optional step 617, the sensor transduces the collected data into electrical signals or into a suitable format for storage.
In step 618, the sensor stores the data from step 616 or the transduced data from step 617 in memory. Step 618 is optional. For example, when present, the memory may be data storage 406.
In step 619, the sensor transfers data to a near field transceiver. In an embodiment, the near field transceiver is on the same PCB as the sensor and the sensor may transfer the data to a near field transceiver memory (e.g., shown in
In step 622, the near field transceiver receives data collected by a sensor. The data may be received via an interconnect on a PCB or via memory shared by the sensor and the near field transceiver. The near field transceiver may receive the data periodically or intermittently. In an embodiment, the near field transceiver may query the sensor for data.
In step 624, the near field transceiver determines one or more tags to transfer the data received in step 622. In an embodiment, the near field transmitter transmits data to a predetermined tag. In another embodiment, the near field transmitter interrogates tags in its immediate vicinity or near field range and selects one or more responsive tags to transmit to.
In step 625, the near field transceiver sends a storage command such as the “Write” or “BlockWrite” command specified in the EPC Gen 2 specification to one or more tags determined in step 624. The command may indicate that the near field transceiver is about to transmit data for storage. In other RFID protocols, there may be no need to signal prior transmission of data.
In step 626, the near field transmitter formats the data according to an RFID protocol such as EPC Gen 2, if required, and transmits the formatted data to one or more tags determined in step 624 using an RFID protocol such as EPC Gen 2.
In step 630, the reader determines one or more tags to interrogate for data. In an embodiment, the reader interrogates a predetermined tag for data. In another embodiment, the reader interrogates tags within in its range and selects one or more responsive tags to receive data from.
In optional step 631, the reader uses a command such as the “Read” command in the EPC Gen 2 specification to instruct one or more tags selected in step 630 to backscatter data stored in their memory.
In step 632, the reader receives and processes backscattered data from one or more tags. The reader may receive similar or different data from one or more tags. For example, the reader may receive temperature and light conditions from distinct tags. In another example, the reader may receiver multiple temperature values from distinct tags and average them.
In step 636, a tag receives a “Write” or “BlockWrite” command from a near field transceiver.
In step 638, the tag receives data from the near field transceiver.
In step 640, the tag stores the data received from the near field transceiver in an internal memory.
In optional step 642, the tag receives a command such as the “Read” command as in the EPC Gen 2 specification from a reader.
In step 644, the tag backscatters data stored in step 640.
By limiting the amount of power required to a level needed to write to tags at proximate ranges, the amount of DC power required to generate the RF signals by a near field transceiver 240 is two to three orders of magnitude lower than that used in a far field high power volumetric reader, such as reader 104. This results in a substantial energy savings when operating from for example, battery powered sources. This further results in substantial reductions of generated heat when using a sensor and near field combination as in systems 508 and 510.
By limiting an effective radiated power to an amount required to interrogate at proximate ranges, the radiating antenna (e.g., antenna 244) can be made very small, with a corresponding reduction in antenna gain. This allows the antenna size to be reduced from a bulky 4″ to 6″ square patch, or linear radiator to as little as a 0.7 inch square patch, or other small size. Such an antenna acts as a near field E-field coupling device, although it could also be a near field inductive coupling loop. This antenna has the tendency to radiate very little into the far field, but when placed in close proximity or contact with an RFID tag, such as tag 102, will give up substantially more energy to the RFID tag through the near field coupling mechanism, enabling accurate reads.
By limiting an effective radiated power to an amount required to write to tags at only contact or proximate ranges, the radiating antenna can be made very small, with a corresponding reduction in antenna gain. This reduces the amount of RF susceptibility for a sensor-near field transceiver combination to other interfering readers. Furthermore, this reduces the amount of RF interference that a sensor-near field transceiver combination presents to other readers. Still further, any undesired interaction with other circuitry housed within the mobile terminal in minimized (e.g., when NFTM 240 is housed with sensor 400 as in system 508).
In an embodiment, by placing systems 508 and 510 in close proximity to an RFID tag 102 being read, the tag being read becomes detuned by the presence of antenna 244. It therefore becomes much harder for an interfering reader to jam the interrogation and/or writing process of the present reader.
In an embodiment, systems 508 and 510 as described herein can be made at very low cost (e.g., <$20 in parts) and can operate at low power (e.g., 100 ma @ 5V peak). This is because of the very low cost and very power efficient components utilized by systems 508 and 510 described herein, such as a SAW oscillators, lower power amplifiers, etc. Furthermore, the lower broadcast power enables passing FCC requirements without the need for frequency hopping. This further lowers cost.
In an embodiment, systems 508 and 510 are configured to use a “near-field” antenna configuration, including in a patch, linear, or loop antenna configuration. Another near-field antenna example is a lossy transmission line type antenna.
Furthermore, due to the shorter range of transmitted signals, there is less portal interference. For example, embodiments such as systems 508 and 510 which pair sensors with near field transceivers, may have an interference range of a few meters, whereas if a sensor is paired with a reader, it may have an interference range as much as a mile or more.
In an embodiment a flexible substrate may be used to mount NFTM 240 and SS 400. The flexible substrate may be made from a flexible material, such as a plastic, polymer, or other substrate material that flexes. Because the substrate flexes, and can thus be shaped, it enables circuits to be positioned in and on objects, such as mobile devices, in a variety of configurations. Furthermore, the flexible substrate may have an adhesive backing to enable easy attachment to a surface.
A motion sensor, such as a “MEMS” (micro-electromechanical system) motion sensor, may be present for enhanced power management. For example, a motion sensor may enable the device to go into sleep mode when no motion is being detected.
In this document, the terms “computer program medium” and “computer usable medium” are used to generally refer to media such as a removable storage unit, a hard disk installed in hard disk drive, and signals (i.e., electronic, electromagnetic, optical, or other types of signals capable of being received by a communications interface). These computer program products are means for providing software to a computer system. The invention, in an embodiment, is directed to such computer program products.
In an embodiment where aspects of the present invention are implemented using software, the software may be stored in a computer program product and loaded into a computer system (e.g., a reader or host) using a removable storage drive, hard drive, or communications interface. The control logic (software), when executed by a processor, causes the processor to perform the functions of the invention as described herein. Still further, a sensor may execute computer readable instructions to collect data. Still further, a near field transceiver may execute computer readable instructions to communicate with sensors and/or tags.
According to an example embodiment, a reader may execute computer-readable instructions to read tags, as described above. Furthermore, in an embodiment, a tag may execute computer-readable instructions to respond to a reader transmitted signal, as further described elsewhere herein.
While various embodiments of the present invention have been described above, it should be understood that they have been presented by way of example only, and not limitation. It will be apparent to persons skilled in the relevant art that various changes in form and detail can be made therein without departing from the spirit and scope of the invention. Thus, the breadth and scope of the present invention should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with the following claims and their equivalents.
