Examples of the present invention relate to the control of equipment and apparatus. More particularly, examples of the present invention relate to systems and methods for wirelessly controlling equipment and apparatus by employing radio frequency identification (RFID) technology.
Many applications of radio frequency identification (RFID) focus on tracking items, for example, through manufacturing processes and through retail chains. Only in a few cases has RFID technology been used to transmit data about the tagged item to the reader. For example, such data as temperature and humidity have been exploited by the United States Department of Defense (USDOD) in RFID applications. The USDOD has tested a modification of RFID tags to sense pressure, temperature, and humidity on high value items. Data is acquired about the environment of the tagged item, but not for controlling a machine or equipment.
Radio frequency identification uses a transponder tag, also referred to as an RFID tag, consisting of an antenna and an integrated circuit chip. When the tag is in the presence of an electromagnetic field (i.e., a radio signal) of proper frequency and sufficient strength, the antenna may receive electrical energy to operate the chip. The energized chip may send out a backscatter radio signal containing digital information with which the chip has been previously programmed. The antenna of the tag may have, for example, dimensions of from a few millimeters to several centimeters, while the chip is usually less than a few millimeters, if it is present at all.
Another component of an RFID system is the reader which may include one or more antennas and a transceiver. The reader broadcasts the radio signal and subsequently listens for the backscatter signal from the tag or tags in the working range and detects the digital information. The reader interfaces to the remaining part of the system (e.g., a coded door lock, a computer database in a world-wide supply chain, or other applications).
Operating frequencies in the United States exist in several unlicensed radio frequency bands. For example, a low frequency (LF) band which is around 125 kHz is used for short range applications near fluids, a high frequency (HF) band which is around 13.56 MHz is used in manufacturing and parts tracking, and an ultra high frequency (UHF) band around 915 MHz is used for long-range applications. Microwave applications, for example 2.4 GHz are in use as well. It should be recognized that any desired frequency or frequency bands may be used in accordance with the invention. In other countries, similar but slightly different bands are in use. For reasons of international operation, efforts are underway to standardize frequencies between countries.
Examples of operational powers range from several milliwatts to a few watts, providing operating ranges of a centimeter or less out to about ten meters. An operating range of 50 feet for passive RFID tags has been reported.
Many RFID systems use passive tags that have no batteries, deriving operating power from the received radio signal and having unlimited useful life. Some systems use tags that include batteries to assist the operation of the chip and provide an extended range of operation. Such tags are referred to as being active, and have a useful life of, for example, two to three years. Some active tags periodically emit brief radio signals referred to as chirping. Other active tags, referred to as semi-active, only turn on when they detect a radio signal from a reader.
A primary use of RFID has been to track objects such as, for example, items in a retail chain or materials in a supply chain. RFID tracking has significant advantages over bar code tracking. A bar code is read with a manual optical reader and may contain only sufficient data to identify the manufacturer and item type. A common RFID tag may hold 96 binary bits of information amounting to more than 1028 possible different codes. Such information capacity is more than sufficient to uniquely identify not only manufacturer and item type, but also uniquely identify each individual item, for example. Other RFID tags may hold more or less information.
Such an RFID system may replace a bar code manual reader with an automatic reading system that does not have the tight directional restrictions of the bar code reader. Furthermore, radio waves easily pass through many materials that are opaque to light. RFID readers are available which may read many tags nearly simultaneously in a bulk processing environment.
Other uses of RFID technology have become available as well. For example, proximity detection for key-less lock entry is one application, and tags on the shoes of marathon runners to time a race is another application. A recent application to medicine uses RFID to detect esophageal reflux, and combines RFID technology with sensor technology to measure and transmit data from within the body of a patient to a wireless receptor hanging around the neck of the patient.
Further uses of RFID technology are desirable, and examples according to aspects of the present invention will become apparent to one of skill in the art, as set forth in the remainder of the present application with reference to the drawings.
Certain embodiments or examples of systems and methods according to the invention are described herein and provide for wireless remote control of equipment or devices using RFID technology. Such embodiments allow meaningful control information originating at an RFID tag to be transmitted to the controlled equipment or devices. The source of the meaningful control information may be a human operator, for example, operating a handheld or other control pad or system. In other embodiments or examples, the systems and methods may be generalized to include non-human sources of meaningful control, such as a part of a machine actuating a control signal, for example.
Certain embodiments of systems and methods herein may utilize battery power supplies or may not require batteries or any other power source at the RFID tag. RFID tags or devices according to examples of the invention may receive the electrical energy needed for their operation from an interrogating radio signal. However, battery operation is possible as well using active or semi-active RFID tags. Tags have been demonstrated that have no IC at all, but only the antenna generating backscatter. From the point of view of the present invention, these could be used as well in select embodiments that will be described. Embodiments of systems and methods herein provide a virtual connection (or disconnection) of a control tag to the controlled equipment. Further, the systems and methods may utilize the built-in identification component of the tag, to make each virtual connection unique.
Systems and methods according to examples of the invention may utilize modified RFID tags and readers, to wirelessly control electrical equipment or devices. Controlling codes may be generated at a tag by mechanically shielding or exposing one or more tags such that a reader may read only desired exposed tag identification(s) or ID(s). The reader may then interpret the control action from the specific ID(s) read. If the tags are active and battery powered, then the batteries may be selectively connected to the tags to be activated when desired. Again, the reader may interpret the requested control action from the specific ID(s) read.
Furthermore, in examples of the invention, tag ID bits may be used as code bits to encode the control request. Alternatively, in addition to the ID bits, additional bits may be implemented to be used as code bits. To permit management of these code bits at the tag, pins may be added to the tag integrated circuit (IC) to allow such code signals to be brought into the IC. A portion of the equipment or device to be controlled may include a modified reader. The reader may check a received ID for validity and then interpret the control request to the equipment or device being controlled.
These and other advantages and novel features of the present invention, as well as details of illustrated embodiments thereof, will be more fully understood from the following description and drawings.
a is passive switch addressing scheme using all possible combinations, and shows a table representing the addressing scheme.
b is a circuit diagram of the example shown in
a-11e are flow charts showing details of the method of
Turning now to the Figures, various examples or embodiments of the present invention use RFID tags and associated systems as a mechanism to wirelessly generate and transmit control codes originated by a person, equipment or other suitable source, to a system that responds to that control request.
As an example, such a system could be a wall mounted switch that may include two RFID tags with the switch lever mechanically connected to a RF shield that alternately exposes one or the other tag (see
In accordance with another embodiment, a method to cause the one or more RFID tags to effectively transmit a control code is provided using active tags. A battery (or batteries) of an active tag is switched on or off, resulting in selection of the tag(s) whose identifications are desired to transmit one or more control codes. For example, consider a simple two-tag, on-off system similar to the previous example of
In accordance with certain embodiments, an external mechanical input device or system can be used to selectively expose any pattern of a plurality of tags. Relating to this,
In alternative examples in accordance with certain embodiments, the tag mechanical support may be moved, leaving the shield in a fixed position. Both
As a further alternative, in a similar manner, the shorting of sections of an antenna associated with the RFID tag can be accomplished by a short section of wire or other conductor.
In accordance with another embodiment, a method to enable the use of RFID technology to remotely control equipment is implemented by making modifications to the chip in the tag. One or more pins on the chip are provided to permit information generated by manually operated switches, or generated by a control instrument, to modify a portion or all of the stored information in the tag. As a result, a next read may contain a modified code that may be interpreted by the reader to generate a new request to the controlled equipment. Each tag may be assigned a range of identification numbers in which some bits may be fixed and one or more bits may be controlled by external switches through the external terminals, for example. Alternatively, each unique ID of a tag may simply have a few variable code bits appended to it.
Regardless of details of how code bits are included with the ID bits, the 0 or 1 state of each of the control code bits may be controlled by the external switches or other suitable arrangement, to provide a plurality of control codes. For example, with 5 bits designated as control code bits, 25=32 different control codes are available. In general, with N bits available to the control code, the number of control codes follows the well-known exponential relationship:
number of control codes=2N
As is described with reference to another example, six (6) external pins on a tag's chip are used to enable a five (5) bit code. By extension, an implementation calling for a sixteen (16) bit code environment (permitting 65,536 different control codes) may use seventeen (17) external pins. While such parallel data transfer is a possible approach, various methods to transmit data serially between components on a common circuit board are well known and may require only a few signal lines.
In accordance with additional embodiments, external signal input pins are provided to the IC (integrated circuit) of the tag. Switches that are properly attached to the pins may provide user adjustable binary information to the chip. As a result, the chip can transmit back to the RFID reader, binary information that is changeable according to the user's switch settings.
In accordance with certain embodiments, a many-switch keypad controller is provided. The concept of a battery-less, wireless keypad controller has potential for a keypad containing only a few switches or actuators such as pushbuttons or the like. This may be expanded out to an application with many switches, such as are found on some modern television remotes or on a PC (personal computer) keyboard for example. Though this may be performed using a plurality of pins on the chip of the tag, it is also possible to implement such an arrangement by the use of a battery to drive the typical keypad/keyboard interface circuit. This circuitry could provide such functions as key scan, debounce, and encoding. A few pins may then be used to transfer those coded results to an (active) RFID tag to make the wireless connections to the TV or computer.
To make the keypad/keyboard completely wireless and battery-less, a more passive keyboard circuit may be used. Key switches could be encoded by passive connections, as opposed to an active circuit. This may be achieved with a matrix addressing circuit for example. In a matrix circuit, each key, when pressed connects three or four or more terminals together, one of which is a reference node (e.g., electrical ground). By providing three contacts under each switch, two-dimensional matrix addressing is provided. By providing four contacts, three-dimensional matrix addressing is provided. Higher order matrix connections are possible as well, in accordance with various embodiments. When such low-power, or wireless and battery free type keyboard circuits are desired, functions such as switch decoding and debouncing could be preformed in the reader and interface portion of the system, where electrical power is already available.
For example, see
The four row pins, four column pins, and one ground pin nine pins total, 51, allow sixteen (16) switches in this example. In general, the optimum area is a square such that, with N rows and N columns,
number of keys=N2,
number of chip pins=2N +1.
This may be acceptable for sixteen (16) switches, however, pin count gets into the twenties for 100 or so keys.
The three-dimensional matrix keeps pin count modest for 125 keys or more. In
number of keys=N3,
number of chip pins=3N+1.
Therefore, with N=5, 125 keys may be addressed which is more than enough for a full keyboard, using only sixteen (16) pins, wireless and no batteries.
It should be recognized that the matrix addressing scheme described above is only one pattern that may be used to assist in thinking about and designing a wireless very low power keyboard. To generalize from this matrix addressing scheme, the circuit may be based on each key pad bringing a unique selection of k signal lines in contact with the common node when that key is pressed. This amounts to selecting k signal lines from the total number of signal lines, call that t signal lines, available to the keyboard circuit. Each of the t signal lines is uniquely connected to an input pin. So in general, when t signal lines plus the 1 common node are available and a unique combination of k of those signal lines are terminated at the contacts under each switch, then the number of key switches that can be supported can be found from combination counting:
number of keys=C(t,k)=t!/(k!(t−k)!)
Looking at this addressing scheme this way, the two-dimensional matrix scheme of
C(8,2)=8!/(2!·6!)=40,320/(2·720)=28
The theory of this matrix and combination addressing is more fully developed in the section “ADDITIONAL DETAILS”.
With the novel change in the typical PC keyboard type of circuit that is an example of this invention, it can be used to make the keyboard wireless, and require less battery power or no battery at all. The circuit typically utilized for a PC keyboard, wireless or not, includes a two-dimensional row and column matrix of signal lines with each key facilitating a switch at each row-column intersection. Active circuits then scan these signal lines to detect specific key presses. Using circuits and addressing schemes similar to those described herein, the need for scanning circuits is eliminated and with radio frequency interface being accomplished with RFID type technology, the need for battery power is greatly diminished or eliminated altogether.
An additional advantage that may be obtained using this wireless keyboard method is that each transmission from the keyboard automatically comes with a unique identification, the tag's ID. This can assist the host PC to distinguish wireless signals originating in the specific keyboard from the wide variety of wireless signals originating in other sources commonly found in many a modern environment.
In implementing a wireless keyboard such as described herein, the reader may be embedded in the controlled equipment (e.g., a television or a personal computer) and the decoding, switch debouncing and other functions, often performed in the keyboard circuitry, are performed in the reader and its interface circuitry, in accordance with an embodiment. A fast tag and reader may help to accommodate fast key strokes and decipher near simultaneous key presses. Various switch encoding techniques or approaches may be used as may be desired for various particular applications.
In accordance with various embodiments, the reader portion of the controlled equipment is configured to respond in a particular manner to received identifications and/or control codes. The reader may be an embedded reader that is directly built into the equipment to be controlled, monitored or the like, with tags also possibly being embedded in the equipment to be controlled. Alternatively, for various applications, it may be possible that the reader and/or one or more tags are not embedded. In either event, the reader may compare the identification portion of the received signal to a stored list of virtually connected tags, rejecting those not connected. The reader then may properly interpret the control portion of the received signal, implementing the corresponding control action. For example, a first valid ID of a tag may turn a lamp (e.g., the load in
In some embodiments, the reader embedded with the controlled equipment may have, for example, a non-volatile memory to retain the list of tags to which the controlled equipment should respond. This list represents the tags that are virtually connected. The tag to reader virtual interface may be connected or disconnected in any suitable way, and various embodiments are described for reference. For example, a “connect” actuator may be provided on the equipment to be controlled, along with a “disconnect”, or a “clear” actuator. These functions would likely be utilized only at times of installation, remodeling, repair or similar infrequent operations. Such a “connect” action may be to bring the switch to be connected into the read range of the reader. In this way, pressing the “connect” pushbutton and, while pressed, activating the switch, this virtual connection may be accomplished. Selective “disconnect” may follow a similar procedure while a “clear” may delete all identifications from the stored list in the reader portion of the equipment. Such a tag to reader interface may be hard wired at the time of manufacture, or may be established in the field or in any other suitable manner.
In some RFID implementations, a tag, whether active or passive, may transmit a preprogrammed identification code. In wireless operation of equipment, in accordance with embodiments of the present invention, using the concept of enabling or disabling one or more tags, the tag's transmitted identification data indicate both the control action to be taken and the status of the virtual connection. In wireless control of equipment using the concept of providing one or more control pins for external connection to the chip, the chip of the tag is used to transmit a binary control code along with its unique identification. This can still carry the status of the virtual connection using basic methods already described.
In an effort to enhance reliability and minimize energy consumption even in the equipment being controlled, multiple strategies are possible. When a significant amount of time passes without any new signal identity or control request coming back to the transceiver, the transceiver can be made to transmit inquiring radio signals at much lower rate. Also, in such times of less activity, transmissions may be of lower power. To compensate for lowering transmission rates or power, any new receptions can be validated by a brief burst of higher than normal transmit rates or powers to verify a new request(s).
This invention describes ways in which RFID technology can facilitate wireless control of electrical equipment. In some embodiments the control point may comprise of one or a plurality of individual electrical signals each mechanically controlled by the process of opening or closing a switch. The mechanical operation of the switch may be initiated by machine or by human action. In other embodiments, the control point may consist of one or a plurality of other signals, such as photoelectric, photovoltaic, relay generated, or originating from any suitable source. Throughout the body of this disclosure, the words “switch,” “pushbutton,” “key”, or “key-switch” may be used with the intention to emphasize various exemplary implementations, however, those words are, in the final analysis, interchangeable.
As described in this invention, the electrical equipment being controlled will be accompanied by an RFID-type transceiver, or reader, and suitable circuitry to provide the interface between reader and equipment under control. Although terms like “reader”, “transceiver”, “interface circuitry”, “interface”, and “equipment to be controlled” may be used in this document in various ways to emphasize various of these functions, those skilled in the art will notice that any part of these actual circuit functions may be embedded more or less deeply and may be carried out in one or another actual circuit component. Therefore these terms are intended to refer generally to functional concepts, and not necessarily to specific circuit components.
Though most of this paragraph contains information that is familiar to those skilled in the art, it is included here to clarify foundations for methods to be described. When there are many switches serving as inputs, it is necessary to electronically distinguish which switch has been operated. Some methods are used in descriptions in this disclosure, but other methods could be used as well. The methods used herein start with the IC providing signal pins for external connection to the IC's internal circuit. These pins carrying electrical signals are high impedance inputs, each provided with individual internal pull-up resistors. As an alternate example, these pins could provide access to resistor and/or capacitor based circuits internal to the IC, for purposes such as modifying timing characteristics. Then, when a switch closes a circuit between a signal pin and the ground pin, the voltage on that signal pin is forced to be near ground voltage. This will be designated binary 0 at that signal pin. When no circuit is closed between any one signal pin and the ground pin, the voltage on that pin is allowed to be pulled up to nearly the internal supply voltage, or generally left open. This will be designated binary 1 at that signal pin. If the input switches are connected in a circuit such that two or more switches each can provide a closed circuit for one signal pin to be 0, then when any of those switches are closed, the signal pin will be 0, and only when all of those switches are open, will the pin be at binary 1. In summary, open circuit, or high voltage level at or close to internal supply is taken to be binary 1, and that will be taken to be logic true. Low voltage level at or close to ground is taken to be binary 0, and that will be taken to be logic false. Such an approach may allow generation of data over a backscatter RF signal by shorting out the antenna in an on/off type of serial data generation. Further, those skilled in this art will immediately realize that any other common assumption about “high” and “low” voltage range, or about what is taken to be 0 or 1, true or false can be made, and the results will be fundamentally unaltered. The scope of this invention is not limited to any one set of these assumptions.
A standard way to assign addresses to elements such as memory locations or switches on a keyboard in electronic systems is to assign them in binary counting order, or at least in some coded version of that. In such binary order addressing schemes, any number of the bits or signal lines will be taken to 0 by any addressed switch. This leads to complexities of circuit board design, and makes it impossible to distinguish a near-simultaneous pressing of multiple keys from pressing a third different key. To avoid these problems, the typical PC keyboard uses a well-known row and column scan approach. This requires active circuitry consuming a modest amount of electrical power. (For example, at this PC keyboard, a common keyboard distributed by a well known PC maker, I can generate the following sequence of characters by first pressing t, then additionally pressing h, then release t, then press t, then release h, then press h and so on keeping at least one of the letters pressed at all time, alternately releasing t or h, “thththt.” The keyboard accurately presents t or h instead of presenting a third key such as y.)
The method described here is to use a matrix or modified matrix addressing scheme wherein each key has the same number of zeros in its address; the same number of pins assigned to it. In general, the number of zeros is the selection number k, as used in the combination equation shown in paragraph [0043]. Thus in
Whereas the binary “address” of a pair of keys pressed will always differ from the address of any one key being pressed, it is not necessarily the case that one pair is unique from any other pair. Thus, for example, in
A feature of this matrix addressing scheme is that each item addressed has the same number of zeros (or ones) in the binary address affording easy detection and decoding of the activation of two different addresses at overlapping times. A drawback of the matrix addressing scheme is that it is an inefficient use of available signal lines. Full selection of all possible addresses that are available while retaining the fixed number of zeros feature can be obtained utilizing combinatorial counting. And since the number of zeros in any address is still a fixed number, the ability to detect overlapping activation of two keys is retained. The following table illustrates the comparison between matrix and full combination addressing for a system in which 6 signal lines are available and we compare a 2-dimensional 3×3 matrix addressing with selecting all possible ways to select any 2 items from 6 total available.
The comparison of a 2 dimensional 3×3 matrix with selecting any 2 from 6 signal lines begins to show the comparison of efficiency, but as the sizes increase, the comparison rapidly becomes dramatic. The following table illustrates:
It can be readily seen that the full combination choice is the more efficient in count usage. For example selecting 3 signal lines out of 11 available provides for even more keys than does the 5×5×5 matrix suggested earlier, and it uses 4 fewer signal lines. A wide variety of modifications of these examples is possible. Specific applications will likely inform the selection details.
In some cases, it is envisioned that a special switch input, perhaps a shift key, to the IC may have a special dedicated address such as a unique input pin. This way its function is always independent from all other inputs.
Signals on the pins are low frequency, low rise time, and thus can be made low current circuits so as to not place demands on the already tight power budget. Still, it is envisioned that early implementations of products from this invention may need some battery boost. Such battery requirements will, however, be much less than a wireless keyboard that must scan the keyboard, implement functions such as debounce and decoding/encoding, and generate most of the rf wireless signal.
This will describe
This invention discloses one very specific concept, that of placing radio frequency identification transceiver function with electrical equipment to be controlled, and placing RFID transponder function at the point of control input. This focus aims to maximize energy consuming function in the controlled electrical equipment, where power must in all cases be provided, and minimizes energy consuming function out at the point of control input. This one concept has many different embodiments, and each embodiment has a multiplicity of potential applications. A sampling of what this invention facilitates includes; wireless control using much less, or no battery power, and management of desired communications links by virtue of the RFID tag's built-in identification.
In one of the categories of embodiments, macro modifications to the RIFD transponder(s) are made by the controlling function. These modifications are typically received in the transceiver as a change in which tag(s) are read, and the transceiver, through its interface, can then bring about the desired control function based upon the ID read. Examples of macro modifications described are shielding or exposing some tag(s) from the radio frequency signal, partially shielding or exposing some tag(s), electrically modifying the antenna(s) of some tag(s), and simply turning active tag(s) on or off.
In the other category of embodiments, data modifications to the tag(s) are made by the controlling function. These modifications are received in the transceiver as a change in the data from the tags read, and the transceiver can then bring about the desired control function. Modified data can be modifications of some of the tag's ID bits or modifications of additional data appended to the binary ID. Signal modifications described are in the form of signals external to the tag's IC passing into it by way of pins on the IC. This allows external signals to modify binary bits that are transmitted as part of the tag's response to an interrogation. Various ways of providing these external signals are described, mostly through switches so as to provide a very low power circuit, or a circuit completely free of batteries. To facilitate very low power embodiments that include many switches, an addressing scheme is introduced that emphasizes each switch being connected to a set number, k, of the, t, available signal pins. Theory is presented indicating that the maximum number of switches that can be addressed is the count of unique combinations of k things taken from a set of t things. Since each key has a unique address, the simultaneous pressing of multiple keys can be appropriately detected.
To minimize energy consumed by the transceiver embedded in the controlled equipment, management of repetition rate and amplitude of the reader's interrogating signal is introduced. This can also be used to enhance reliability. The unique identity of each RFID tag easily facilitates the use of memory in the reader and interface function to manage virtual connectivity between control input and the equipment being controlled. The invention uses RFID technology or technology having the functionality of RFID technology to facilitate wireless remote control, with minimal to zero battery usage. The “wireless remote control” is a control action, initiated at the control point, using variations of RFID tag functionality, to cause a change in the control state of some equipment that is interfaced with the RFID reader. An intentional control action is acted upon the RFID tag or the like, with the specific intention to cause a change in the controlled state of the equipment under the control of the reader. Examples may be simply turning a ceiling light on or off, changing the speed of a fan, or changing the operation of electronic equipment such as a TV, stereo, DVD player, etc. The invention may allow such control with usage of low power, or even battery-free, operation at the switch/tag. The invention includes methods for utilizing other energy sources such as piezoelectric. The invention also provides for connecting the tag to reader using a unique method, and the switch/tag can have any number of switched states. The invention allows integrating large numbers of states selected by several switches to the tag's IC, and to cause the reader to change the state of equipment it might be connected to in some examples.
In various examples of the invention, a distinction is made between the point at which control parameter(s) are input or initiated, and the equipment under control. Regarding the “control point” and “equipment under control”, in many situations/environments it is desirable or even necessary for the control point to be separated some distance from the equipment being controlled. In such situations, the control point is connected to equipment using RF instead of wired connections. Implementation of this RF connection with RFID technology, placing the function of the transponder, “tag”, at control point, and the function of the transceiver, “reader”, at equipment. To diminish the need for power, especially battery power, at the control point, place power needy aspects of the control functions at the equipment under control. This provides advantages such as cross fertilization with existing RFID technology. A few of many examples of this may include resolving interference issues, especially in environments like hospitals or the like, between RFID used in item tracking and widely used electronic equipment. In another aspect, utilizing the ID of RFID for virtual connect/disconnect, and for passing control codes. Common applications of RFID raise security issues that are being solved, resulting in security solutions that can be implemented in remote control. The invention also allows environmental and cost savings due to less interconnecting wire, less batteries, and other interconnecting materials, and cost savings of less installation time, as interconnecting wire is not needed, as the hook-up is virtual not physical. Cost savings is also realized in easier remodeling activities. As described with reference to various examples, the invention may also be correlated or combined with existing, related technologies, such as for piezoelectric based remote control applications.
In general, in one aspect of the invention, the system and methods interface the RFID transceiver functionality, “reader”, at the electrical equipment to be controlled and place the RFID transponder functionality, “tag”, at the point of control input. Such a system can utilize many of the RFID technologies presently available, Gen1, Gen2, passive, active, semi-active, or those not yet available. There are a wide variety of applications, such as for example, residential wall switches, garage door openers, computer peripherals, remote controls, industrial applications. The invention includes methods of indicating/initiating control action at the point of control. Two different aspects are being addressed, the control action, and whether a certain control point is or is not virtually connected. As used throughout this application, words such as control action, switch, pushbutton, control signal, control input, all mean basically the same thing. One may be used to emphasize particular details, but this is not to limit the scope of the invention. The control action can be specified by macro modifications to the RFID tag. In these implementations, changes are made in which tag(s) are read by the reader function in the equipment, thus indicating that a change in control state is requested. Some examples of this include having a mechanism to shield a tag from or expose a tag to the radio frequency signal as described in above examples. In an alternative, with two tags, one may be shielded, one exposed, so as to have built in fault detection in that exactly one tag should be read each time. An example above is a representation of a two-tag system. A set of tags with a shield shaped so as to expose some subset of these, shielding the rest, mechanically or otherwise mounted, enables changing which subset is exposed as in examples above. In the tag shielding methods described and contemplated, the shielding may be total shielding of the tag surface area, or shielding only a portion of the tag's antenna can be used as well. This may be understood as a capacitive short-circuit of the antenna, or an actual short circuit may be provided. When shielding or exposing a tag or group of tags, partially or fully, the tag(s) and shield(s) move relative to each other. A variety of options in this regard are contemplated, such as having the tag(s) remain at fixed position and a controlling action moves the shield(s), the shield(s) remain at fixed position and a controlling action moves the tag(s), both tag(s) and shield(s) are moved differently by the controlling action, or combinations thereof. Short circuiting of the antenna can also be accomplished by attaching two wires, one near each of opposing ends of the antenna. When these wires are connected, that tag cannot be read, whereas when open, the tag can be read. Attaching wires to critical spots of the antenna, low frequency amplitude-shift-keying permits transmission of choices from a multitude of control requests. The systems and methods also may use active or semi-active tag(s), with a battery or batteries can be selectively connected or disconnected.
In the systems and methods, the control action may be specified by changing what is transmitted from any tag or tags, be it the ID, and/or a portion of the ID, and/or changing data appended to the ID. For example, through pins (or the like) on the tag's IC chip, there can be brought out circuit nodes that permit these changes. In exemplary implementations, the available pins comprise, a reference node, perhaps “ground”, and one or more high-impedance signal inputs each with a large value resistance returning to a different reference node, perhaps “supply”. For example, for parallel switch input; one SPST pushbutton (or switch) for each signal input pin may be used, with all pushbuttons returning to the ground pin as set forth in the example above. An addressed switch input, typically used where many switches/pushbuttons are needed, may be provided by implementing key scan circuitry at the point of control, perhaps using battery power if needed. To diminish or eliminate the need for a specific power source, implementing passive switch addressing may be provided. For example in a method, let the number of signal input pins available be equal to t. When also counting the “ground” pin, that makes t+1 pins total. Let the maximum number of pins that will be connected to “ground” at any one time be equal to k, where k<t. Each switch or pushbutton is designed to be normally open, with as many as k+1, contacts, one used to return to ground, the others connect individually to the switch's unique assignment of k (or in some cases, perhaps fewer) of the input pins. When a switch is pressed, its input pins are all connected to the “ground” node.
The status of the virtual connection between the point of control and the equipment being controlled is largely maintained by the reader function in the equipment, but tag(s) may also have impact on connectivity. For tag(s) to be connected yet transmit control function(s) some or all of their ID remains unchanged, that ID being stored in the reader-equipment. In cases where ID is changed, such as a multiple tag situation, all valid IDs are stored, perhaps along with the control functions to be implemented upon receiving that ID.
The invention also provides methods of carrying out control actions at the equipment under control. The RFID reader function and suitable interface may be part of, closely connected to, or fully integrated with the actual equipment being controlled. Any portion or the entirety of these functions may be programmed or installed anywhere along the manufacturing process, from the chip foundry, through production, and to installation and even by the end user. This reader and interface function may include aspects and capabilities, as appropriate to a specific application, comprising providing virtual connections, wherein to determine if any particular read is from a connected control point, methods may be included to identify the ID of a connected tag as well as methods to maintain and update this information. In an example,
Memory such as non-volatile memory or look-up table contains information such as ID(s) of the “connected” tag(s) and perhaps interpretation of what action is to be implemented. To build and maintain this “connection” list some or all of the functions implemented may be a) A “connect” switch physically on the equipment under control could, while activated, permit any ID exposed/shielded, or modified, or containing changed data, to be added to the “connected list”; b) A “disconnect” switch could work in the same way as the “connect” switch; c) An “erase” switch could delete all IDs from the “connect list”. Possibly useful software concepts that relate to examples may include Field programmable; Maintain an address of; the start of the list, the end of available memory, the end of the list of occupied memory; Add a new ID to the memory list; Delete an ID from the memory list; Re-organize the list to get rid of hole left by the deletion; Clear all IDs from the memory. An assumption may be made that the memory for this purpose is contiguous.
To interpret control action and interface with equipment, it is possible to read the RFID tag, interpret the ID and the data received, and interface the requested control action to the equipment under control. For example the requested control action could be stored along with the connection IDs. There may also be power saving options in the “reader” function. In many applications, there may be long periods of time with no request for a change in the control state. The following features and benefits are possible to save power. Decrease the transmitted read power, duty cycle, or how often a read is transmitted. As soon as any signal is received suggesting a different control state is being requested, increase read power, duty cycle, or how often a read is transmitted. Maintain this higher level of interrogation until validity of read is adequately confirmed and requested control state again remains unchanged for an extended period of time. RF reflections off moving people provide another indication of pending change in control state, such as someone entering a room. This is another opportunity for the radar feature of RFID to help control the environment of a room.
According to further examples of the invention, there are piezoelectric and photoelectric (solar) powering of RFID tags may be provided for various applications. Applications of these technologies may include interaction with improvements anticipated in the electrical power grid, smart grid, and to basic asset management. Further, additional concepts utilizing surface acoustic wave RFID tags may be provided. Such embodiments may utilize reader chips such as the Intel R1000 or the Indy™ R2000 Reader Chip, a product of Impinj, or other suitable RFID reader chips or like technology. For providing energy sources for active or semi-active tags, the objective of minimizing battery use while obtaining significant advantages from having a source of power on board the remote control system is achieved using alternative sources to battery power. For example, piezoelectric and photovoltaic sources of electrical power are described in the following examples, along with their advantages and suggested methods of implementation. Using a piezoelectric source of energy to enable battery free or less-battery power in applications of active and semi-active RFID technology provides enhanced applications and methods. These energy source features may be used in conjunction with the various systems and methods of the invention, including, but not limited to, methods of initiating control action at the point of control, methods of addressing multiple switches, and methods, inclusive of software flow charts, of interfacing the reader functionality with equipment to be controlled. Utilizing these energy source features with RFID technology further leverages the cross fertilization of these applications with the engineering and technological developments that result from other RFID uses, such as asset tracking. For example, the unique ID on each tag facilitates managing multiple controls. Additional issues such as RF interference and security cross fertilize as well. Passive RFID tags that derive all their operating power from the interrogating radio frequency signal and thus need no batteries. Active tags obtain all their power from an onboard source such as a battery, and semi-active tags obtain some of their power from an onboard source, the balance from the interrogating radio signal. Active and semi-active tags, as the terms are used here, are intended with the broadest meaning, including tags with that broad functionality of utilizing an onboard power source(s) even if going by other names such as broadcasting tags, or battery-assisted tags or semi-passive tags, etc. Although many of the examples of the invention refer to using passive RFID tags to implement remote control of electronic devices, using active or semi-active types may be worthwhile for various applications. Using an alternative to battery power, the use of active or semi-active tags is possible using no or less battery power. As it may be desired to avoid the need for batteries in the remote control or remote switching unit, such alternatives make use of such tags possible while not sacrificing this objective. active or semi-active types may be used in any example if desired, and such use may be based on the assumption that their benefit was in the form of decreasing the need for battery, relative to non-RFID radio frequency remotes, because all RFID tag applications drive the need to be very power thrifty. Thus, remote controls that are based on RFID technology have cost, ease of use, and environmental advantages over other remote control technologies. These advantages stem from battery-free operation or from less battery operation i.e. smaller battery and or longer battery life. Other advantages to using the technology of active or semi-active RFID technology in wireless remote control are also provided. Although passive tags are less expensive and have greater lifetime than active or semi-active types and they can often sustain more harsh environments, active and semi-active tags have several advantages that may also apply well to remote control. Among these advantages are longer read range, they can be read in a wider variety of radio signal environments, and greater functionality is possible since the tag's circuitry does not need to rely completely on the meager power received from the interrogating radio signal. Additionally the reader does not need to broadcast full power radio bursts looking for tags in its vicinity, and in many cases this results in less radio frequency energy in the environment resulting in safety advantages and decrease in radio interference. A further advantage derives from the desire to keep costs of the reader functionality as low as possible. For example, tags that cost $2 to $3 more yet result in more modest demands on the reader function and result in decrease in its cost of $30 to $40 results in an obvious design benefit.
Batteries are typically assumed to be the source of onboard power for active and semi-active RFID tags. An alternative power source may be a photovoltaic source of on board power for active and semi-active tags being used in the applications of wireless remote control. For example handheld calculators powered through photovoltaic cells illuminated by just ambient room light are in common use. To further improve the applicability of photovoltaic power sources, on board energy storage can solve the problem of light as an intermittent source. As the technologies of rechargeable batteries and supercapacitors improve this becomes a more viable way to provide on board power to operate active or semi-active tags for use in remote control. While supercapacitors do not yet have quite the energy density of a good chemical battery, they possess many operational and environmental advantages over rechargeable batteries.
Another alternative may be the use of piezoelectric materials as the energy source for active or semi-active tags, to alleviate or lessen the need for battery power. Although piezoelectric power typically requires mechanical work on the piezoelectric crystal to stimulate any electrical energy from it, in the present invention, the control action is initiated through a mechanical action such as a switch, pushbutton, or cam. This is exactly the mechanical action needed to stimulate electrical energy from the piezoelectric crystal. Electrical energy can be generated from mechanical strain of the piezoelectric crystal. The physical switching action, acting upon a lever, knob, pushbutton or the like, can be coupled to piezoelectric material in such a way that the switching action strains the piezoelectric material, causing the piezoelectric material to produce a voltage difference and thereby power the active or semi-active RFID tag. The very action of that tag coming on and transmitting its signal to the reader function in the equipment under control can in some implementations be a sufficient event to initiate the control request. In other implementations, the switch action changes a feature of the tag such as has been described elsewhere in this document, and it can provide the energy for the tag to carry out the dialog with the reader. That dialog may be what is typical of an active RFID tag, or what is more typical of a semi-active tag, or new protocols or new classes of tags may be beneficial. A possible implementation is one in which the piezoelectric energized RFID tag initiates the radio signal to the reader. This way, the reader needs only to be in a listening mode until it detects a relevant signal. The following examples provide some further illustration.
Some examples of implementation, obtaining useful electrical energy from a piezoelectric material. The piezoelectric energized RFID tag can initiate a radio signal when the piezoelectric crystal is subjected to strain caused by a switch lever. An example block diagram is in
The other end of the interface between piezoelectric material and power supply for the RFID tag is at the piezoelectric material itself. The physical switch, pushbutton, or cam that initiates the control action may be mechanically coupled to a piezoelectric material so that by the action of that switch, pushbutton, or cam, the piezoelectric material is subjected to appropriate strain. Although each application may utilize a different configuration, one of ordinary skill will understand the basic approach. Some examples of implementation, utilizing this piezoelectric energy source to enhance the system are as follows. Relating to the “macro modifications” to a tag as was described earlier, reference was made to turning on or off the battery source driving an active or semi-active tag. Let that now include the switch initiated act of providing piezoelectric source of the power needed. This could be used in a single tag application or a multiple tag, multiple switch application. In applications involving the changing of what is transmitted, typically by utilizing one or several switches connected in one of several ways, parallel signal connections or addressed signal connections, there are several methods by which to obtain electrical power from the switch actions. A few are listed as follows for illustration. Those skilled in the art can develop specifics as needed. Signal switches are set to the proper condition, then a “send” switch has the piezoelectric material interfaced with it to provide the needed power for the tag to make or initiate the communication with the reader. Some or all of the switch actions are mechanically coupled to piezoelectric electrical energy sources. Many of these methods might be particularly suitable when the system also includes some mechanism to store electrical energy, using components such as capacitors, supercapacitors, or rechargeable batteries. Switch action implements the state request at the point of control AND strains a piezoelectric lever, arm or the like, to generate the electrical energy to cause the RFID tag to send out a radio signal. Each signal switch obtains its mechanical feel, action, or response in part or in whole from a piezoelectric material which in turn provides, or adds to, the power source. The signal connections of the signal switch are electrically separated from the mechanical-power generation of the switch. The signal circuits, involving the pushbutton's signal contacts, as discussed so far, are unchanged. The pushbutton's mechanical support has piezoelectric material and its electrical contacts added. Alternatively, an approach to more directly combine the signal action and the power generation action such that the addressing or signal circuits also carry power to the chip. The tag can typically remain in a low power state, such as the “sleep” state available on many microcontrollers, and wake up only when a change on signal inputs is detected. Upon waking up, it initiates dialog with the reader function. Reader and tag complete the necessary communication, and the tag goes back to sleep. Other solutions are possible, and the particular choice depends upon details of an application.
Some examples of implementation, obtaining useful electrical energy from photovoltaic supply, and utilizing this energy source to enhance the system. Methods of obtaining useful electrical energy from photovoltaic sources are based on issues of energy storage and voltage regulation. Some mention of these methods has already been made and those skilled in the art can readily make adjustments and additions as needed in a specific application. To utilize tags powered with a photovoltaic source many methods already described for passive tags as well as methods described for piezoelectric tags will work with minor adjustments. The key difference between photovoltaic on one hand, and passive and piezoelectric on the other is that the power source, or at least part of it, is already available, and not dependent on either the reader's radio signal or the mechanical actuation of a switch. Specific examples of using a photovoltaic powered active or semi-active tag are as follows. The previously described macro modifications can be used, especially using the acting switch(es) to connect or disconnect the power source to or from the tag(s). The previously described methods referred to as “changing what is transmitted” from the tag will work here. The tag can typically remain in a low power state, such as the “sleep” state available on many microcontrollers, and wake up only when a change on signal inputs is detected. Upon waking up, it initiates dialog with the reader function. Reader and tag complete the necessary communication, and tag goes back to sleep.
Using the wireless control system to enable interaction with the smart grid of the future. Once control of equipment is electronic, and especially wireless, it will be easier to interface with the smart grid. Smart grid refers to applying state of the art control methods to improve the electrical power distribution grid. Smart grid protocols are being developed by agencies such as Federal Energy Regulatory Commission (FERC), National Institute of Standards and Technology (NIST). With control of equipment based upon electronic methods, it will be more straightforward to install needed capabilities into the system. A few examples of the capabilities that may be beneficial follow. One of the major challenges to the power grid is when many loads such as air conditioners, or ceiling fans cycle on and off at the same time. This makes the grid is at one time over utilized, and then under utilized. So a solution is to permit the user to opt for an optional load to be on only when another load is off, or only when rates become lower, a sort of “auto save money” option that could then be reflected in a lower rate at the meter. Alternatively, when a user does request to turn on a load, the remote control could briefly flash a light emitting diode or make some other signal to indicate that now might not be the best time to bring it on. Request “ON” a second time immediately following the first request to override that suggestion and pay the higher rate anyway. Or pause a few seconds and then request “ON” the second time to implement “auto save money” turn on.
The use of piezoelectric powered tags in asset tracking applications may also be provided. There are item or asset tracking applications in which active or semi-active tags are very desirable. Yet it may often be useful to avoid the expense, financial, environmental or other, of using batteries. A possible solution exists in including an inertial-strained piezoelectric energy source for an active or semi-active tag. An example of implementing an inertial-strained piezoelectric energy source may include placing the piezoelectric material in a small tube. Fix one end of the piezoelectric material to one end of the tube, this also being the end to which its electrical wires are attached. Attach a small mass to the other end of the piezoelectric material. And, of course, this tube is attached to, and a part of the RFID tag. Then every time the tag is subjected to mechanical acceleration of almost any kind, bumped, moved from a rest, dropped or set down, the piezoelectric material generates an electrical signal. The qualifier “almost” is needed to recall that acceleration, linear or rotational, is a vector. So the orientation of the piezoelectric material may, in some applications, be important. One possible solution is to use multiple piezoelectric sensors, oriented in special, likely orthogonal, directions. This concept may be applied to RFID technology to provide various functionality. This opens a variety of possible applications for RFID-based item and asset management. Since a stationary item need not be tracked, presumably the data base knows where it is, and as long as it no longer hears from it, that is good. The reader will hear from it as soon as it is moved. Such a system could also measure shock and mechanical accelerations that an item is subjected to in transit. Piezoelectric microphones are common. This can be the basis for this application, and leads to the possibility of using these as environmental sensors even in battery powered RFID tags. These concepts can be generalized from specifically a piezoelectric material to any accelerometer as the source of the ability to locally measure acceleration, shock, bumps, spin.
Many applications of piezoelectricity, such as accelerometers or microphones, require accuracy, or at least linearity. Some of the applications envisioned in this invention do not require accuracy or linearity, only sensitivity, reliability and low cost. This would be the case in some applications developed below, such as detecting that a tagged item in stock is being moved, or theft prevention. Here, it is often best to simply detect that an item is being moved, such movement causes the tag to emit a radio beacon, the RFID reader receives that, and follows the tagged item using other already developed RFID and tracking methods. In cases where acceleration measurement need not be accurate, and perhaps it is only being used to cause the RFID tag to emit an initial radio beacon, physical mounting of the piezoelectric material can be modified with emphasis on sensitivity at appropriate levels and reliability. One way to enhance sensitivity is to provide a cantilever support for the piezoelectric material, and as needed, attach a modest mass to the free end, such as shown in
Sensitivity can be controlled by appropriate adjustments in the length, cross section, and internal construction of the piezoelectric beam. It can also be controlled by appropriate adjustments of the mass at the end of the piezoelectric beam. Whenever a physical structure such as
In yet another embodiment of the same basic idea, instead of relying on a counter in the integrated circuit, use a fixed number, I, of signal lines to sense actual position along the travel of the slide path. With optimum design of the contacts available to those signal lines, the following well known binary equation holds: N=2I
In the example shown in
In another aspect of the invention, switch-initiated alterations to a SAW tag are possible. A surface acoustic wave (SAW) tag is basically an RFID tag, but is unique in many ways. It is similar in that it has an antenna to interact with a radio frequency signal, for example 2.45 GHz, but it is different in that it does not need to generate DC power with which to operate the tag. Instead, the antenna is attached to an interdigital transducer (IDT), and the radio signal received by the antenna causes surface waves, also known as Raleigh waves, on the substrate. Additionally, the SAW tag includes a series of well positioned individual electrodes to act as reflectors. These reflectors reflect waves back to the IDT in a unique pattern representing the tag data. The IDT then converts the waves back into a radio frequency signal that is somewhat different from the received signal and when radiated back to the reader, carries the tag data. Switches can be arranged to modify the SAW tag and thereby modify the returned radio signal. This then would allow the reader function in the equipment under control to interpret the modified return signal and initiate control action in ways similar to what is described elsewhere in the patent. A few suggestions of methods to modify the SAW tag using switches, pushbuttons, cams or the like follow. The switch can bend the piezoelectric substrate slightly thus modifying the relative positions of the IDT and reflectors, and therefore modifying the reflected signal. Make macro modifications as suggested elsewhere in the examples of the invention, such as short circuit the antenna in any of several ways to “hide” the particular SAW tag from the reader. Switches can clamp onto one or more reflectors thus modifying their reflective properties and or the surface wave returned. Switches can interface with the IDT. There are some indications that SAW tags may soon be sufficiently inexpensive and small that one tag could be attached to one or just a few switches on any multi-key application. The switch(es) would then interface with the tag using one or a combination of the methods just mentioned. So the switch to SAW tag ratio can be optimized for any specific application.
In
In further example of the invention utilizing piezoelectric or other accelerometers to build a novel application to a traditional RFID application, asset tracking, and switch-initiated alterations to a SAW tag. Firstly, for use of piezoelectric powered tags in certain asset tracking applications. In passive operation it is envisioned that the accelerometer itself, upon significant movement, generates sufficient output power to at least cause the tag to transmit a signal that will initiate dialog with the reader. This might not be “passive operation” in the purest RFID tag sense, perhaps in some respects it is semi-active because the tag initiates the dialog. But it is passive in that the tag has no battery. In active operation, a combination is envisioned whereby the signal from the accelerometer (and this could be any of several accelerometer types, such as piezoelectric, capacitive, or piezoresistive) wakes up a tag that has gone into a very low power standby mode (in the jargon of many families of small electronic devices, sleep mode) and then the tag carries out appropriate dialog with the reader. The accelerometer in this case can be thought of as providing an additional battery saving function to the tag. There exists an almost continuous spectrum of possible variations on these two themes, as can be developed for any particular application.
For switch-initiated alterations to a SAW tag, current SAW RFID can support 108 identifications, and may become an integral part of the consumer's product, not a throw-away tag affixed to an item of merchandise. In an example of a larger ID implementation such as a computer keyboard, using for example 125 keys, this provides about 800,000 totally distinct possible keyboards. The chance of unintended matches is quite small even if many more than this are made. The SAW tags also can be influenced by external actions upon the SAW RFID tag, such as on the returned signal. Temperature, torsion and pressure may deform the crystal slightly, thereby changing the shape of the acoustic wave as it travels across the reflectors. Thus, by analyzing the wave deformations, the interrogators can also determine a SAW tag's temperature and the shock or pressure to which it is being subjected. The SAW tag may thus be used both for identification and for sensing environmental factors.
According to the invention, further suggestions regarding methods of implementation may include the following. Many of the “macro modifications” for silicon-based RFID would apply here; shielding, partial shielding, short-circuiting the antenna. Additional “macro modifications” are envisioned, such as switch action bending the SAW RFID tag. Much information is out there stating that this changes the returned signal in ways that are detectable. Switch action twisting the SAW RFID tag. This suggests use of a selector dial with perhaps a spring to provide the correct feel, using methods well known to those skilled in the art. Those skilled in the art can readily see that bending or twisting could be implemented by either a toggle switch, cam, rotary knob, or other suitable arrangement. In general, entities, such as switches, external to the SAW RFID tag can be made to interact with the tag in such a way that the returned signal is detectable as modified from what would otherwise be detected. It was mentioned an example with switches interacting with the SAW RFID tag. In
The examples and methods described to make this happen are described along with procedures and some flow charts, methods ranging from macro modifications on passive tags to tags with switched inputs and piezoelectric sources of electrical energy at the tag, and include examples from wireless computer keyboards to semi-active tags with piezoelectric accelerometers to detect motion of the tagged item. A large variety of other applications are within the scope of the invention, and would occur to those skilled in the art, and are encompassed within the claimed invention.
While the invention has been described with reference to certain embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from its scope. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed, but that the invention will include all embodiments falling within the scope of the appended claims.
Number | Date | Country | |
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61058950 | Jun 2008 | US |