Low-power radio frequency identification reader
Abstract
A low energy radio frequency proximity reader system comprising: a tag reader (12) that functions to detect identification tags by evoking an identification response of identification tags that are present within a field of detecting said reader; a secondary detector (20) that functions as a motion detector to detect the entry of an object, including the waving movement of a hand in front of the tag reader, and including without limitation the entry of identification tags in said field of detection by means other than the evocation of a radio frequency response from said object and to obtain an enable control signal in response to said detection; power supply means (14) for supplying operating energy to said tag reader and said secondary detector, whose detector and whose tag reader each have an average operating energy requirement, said detector being selected to have a average operating power requirement substantially less than said tag reader; and an energy control switch (16) characterized in that the power control switch (16) normally keeps said tag reader disconnected, and it works to activate said tag reader in order to transmit radio frequency signals intended to evoke a radio frequency response of identification tags only for a limited period of time sufficient to detect an identification tag if it is present in said detection field in response to said enable control signal; in such a way that operating energy is conserved by activating the tag reader only after the entry of the object in the detection field of the tag reader.

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Projected expiry passed 21 April 2020, 6.4 years ago.
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9 claims: 3 independent, 6 dependent
- 1ES 2 284 497 T3 REIVINDICACIONES 1. Un sistema de lector de proximidad de radiofrecuencia de bajo consumo de energía que comprende:un lector (12) de etiquetas que funciona para detectar etiquetas de identificación mediante la evocación de una respuesta de identificación de etiquetas de identificación que se encuentren presentes dentro de un campo de detección de dicho lector;un detector secundario (20) que funciona como un detector de movimiento para detectar la entrada de un objeto, incluyendo el movimiento de ondulación de una mano por delante del lector de etiquetas, e incluyendo sin carácter limitativo la entrada de etiquetas de identificación en dicho campo de detección por medios distintos a la evocación de una respuesta de radiofrecuencia desde dicho objeto y para obtener una señal de control de habilitación en respuesta a dicha detección;unos medios (14) de fuente de alimentación de energía para suministrar energía de funcionamiento a dicho lector de etiquetas y a dicho detector secundario, cuyo detector y cuyo lector de etiquetas tienen cada uno un requisito de energía media de funcionamiento, seleccionándose dicho detector para tener un requisito de energía media de funcionamiento sustancialmente menor que dicho lector de etiquetas;y un conmutador (16) de control de energía caracterizado porque el conmutador (16) de control de energía normalmente mantiene desconectada a dicho lector de etiquetas, y funciona para activar dicho lector de etiquetas con el fin de transmitir señales de radiofrecuencia destinadas a evocar una respuesta de radiofrecuencia de etiquetas de identificación solamente durante un período limitado de tiempo suficiente para detectar una etiqueta de identificación si está presente en dicho campo de detección en respuesta a dicha señal de control de habilitación;de tal manera que se conserva energía de funcionamiento mediante la activación del lector de etiquetas solamente tras la entrada del objeto en el campo de detección del lector de etiquetas.
- 2El sistema de lector de la Reivindicación 1, en el que dicho lector de etiquetas tiene un circuito transmisor y un circuito receptor conectados a una antena para transmitir una señal de interrogación de radiofrecuencia y descodificar una respuesta devuelta por etiquetas de identificación que se encuentren dentro de dicho campo de detección del lector de etiquetas.
- 3El sistema de lector de la Reivindicación 1, en el que dicho detector secundario es un detector pasivo por infrarrojos.
- 4El sistema de lector de la Reivindicación 1, en el que dicho detector secundario se selecciona del grupo comprendido por detectores por infrarrojos, inductivos, electrostáticos, por microondas y por ultrasonidos.
- 5El sistema de lector de la Reivindicación 1, en el que dicho período limitado de tiempo es aproximadamente el período de tiempo requerido para transmitir una señal de interrogación de radiofrecuencia y recibir y descodificar una respuesta de una etiqueta de identificación presente en dicho campo de detección, y ejecutar una función de control de acceso por dicho lector de etiquetas.
- 6El sistema de lector de la Reivindicación 1, en el que dicho lector de etiquetas provee una señal de control de desconexión a dicho conmutador para devolver dicho lector de etiquetas a un estado de energía limitada.
- 7Un método de hacer funcionar un lector (12) de proximidad de radiofrecuencia que tiene un campo de detección, cuyo método comprende:mantener en un estado de espera a dicho lector de proximidad de radiofrecuencia;detectar (20) el movimiento dentro de un campo visual que generalmente se solapa con dicho campo de detección de dicho lector de etiquetas;y caracterizado por;mantener a dicho lector de proximidad de radiofrecuencia en un estado de espera en el que dicho lector de etiquetas está inhabilitado de efectuar emisiones de radiofrecuencia;activar dicho lector de radiofrecuencia en respuesta a dicho movimiento para transmitir señales de radiofrecuencia sólo durante un período de tiempo generalmente suficiente para evocar una respuesta de una etiqueta de identificación si ésta se encuentra presente en dicho campo de detección;y devolver a dicho estado de espera a dicho lector de proximidad de radiofrecuencia.
- 8El método de la Reivindicación 7, en el que dicha etapa de detectar comprende detectar un cambio en una característica de dicho campo de detección seleccionada de un grupo que comprende un fondo de infrarrojos, reflectividad por microondas, reflectividad por ultrasonidos, inductancia y capacitancia. ES 2 284 497 T3
- 9El sistema de lector de cualquiera de las Reivindicaciones 1 a 6, en el que el detector secundario (20) funciona para detectar movimiento dentro de un campo visual que generalmente se solapa con el campo de detección del lector (12) de etiquetas.
Independent claims9
31 paragraphs in 3 sections, as filed
ES 2 284 497 T3
DESCRIPTION
Low energy consumption RFID reader.
Background of the invention
Field of application of the invention
This invention relates to radio frequency identification readers used in conjunction with identification tags in controlled access systems, and more particularly directed to low power consumption proximity readers suitable for battery powered operation.
Prior state of the art
Radio frequency identification systems (hereinafter RFID systems) have come to reach a very wide use and generally include a reader, typically installed in a fixed location, and a population of portable identification (hereinafter ID) tags. Each ID tag contains a transponder unit that returns a coded response when interrogated by radio frequency transmission from the reader. The reader periodically sends a transmission intended to evoke a radio frequency response from any of the ID tags within range of the reader. The tag response includes encoded identification data based on which the reader makes a decision to authorize or deny access to the controlled facilities. RFID systems could use active tags that carry their own source of electrical power such as a battery, or passive tags that contain no power source and that instead rely entirely on the energy radiated by the reader unit. Passive tag readers continuously or periodically scan for the presence of passive tags in the vicinity of the reader by transmitting energy that activates any tags present. A passive tag does not announce its presence unless it is activated by the reader. In addition, the passive ID tag requires that sufficient radio frequency energy be received that, when converted by the tag into an electrical current, will support the operation of the tag's electronic circuitry. Accordingly, the operating range of the reader / tag system is largely determined by the energy transmitted by the reader, and the ID tag must come in sufficient proximity to the reader for the tag to be activated. For this reason passive tag readers are also known as proximity readers. Proximity tags typically have substantially higher operating power requirements than RFID active tag readers of comparable range, and the development of portable battery-powered proximity readers has been hampered by excessive battery power consumption.
There is a continuing need for RDIF readers with lower operating power requirements and, in particular, for a low power proximity reader that can be adequately powered by batteries for portable use.
US-A-3859624 is acknowledged in the preamble of claim 1.
Summary of the invention
The invention is specified in claims 1 and 7.
The present invention satisfies the aforementioned need by providing a low power consumption radio frequency identification reader system that includes an RFID tag reader that functions to detect and verify the presence of identification tags present within a field. detection of the reader by evoking a radio frequency response from the identification tags, and a secondary detector that operates to detect a change in the detection field of the RFID tag reader indicating the possible entry of an identification card into the detection field of the reader and to obtain an enable signal that responds to said change. By detecting such changes, the secondary detector serves to detect the entry of an object into the detection field, but by means other than the evocation of a radio frequency response from said object.
An electrical power supply has been provided to supply operating power for the RFID tag reader and for the secondary detector. The detector and reader each have an average operating power requirement, and the secondary detector is selected to have a substantially lower average operating power requirement than the reader. A power switching circuit normally limits or cuts off the power from the power supply to the RFID tag reader while powering the secondary detector. Maximum operating power for the RFID tag reader is enabled by the power switch circuit for a limited period of time in response to the enable signal in order to verify the presence of an ID tag and, if applicable, thus, to allow access to controlled facilities. As a result, the RFID reader is relegated to a low duty cycle relative to the secondary detector and the maximum or average operating power of the reader system is conserved only by operating the RFID tag reader briefly after a physical change is detected. such as movement in the reader's detection field indicating the possible presence of an ID tag.
ES 2 284 497 T3
Although the low energy RFID tag reader system of this invention is not limited to any particular type of RFID reader, it has been found to be most useful with proximity or passive tag readers, due to their requirements for relatively high operating energy. For this reason, in a preferred form of the invention, the RFID reader is a proximity reader intended to detect the presence of passive identification tags.
The secondary detector is not limited to any particular detection technology. Rather, the secondary detector should be chosen so that it consumes little power compared to the RFID reader so that significant energy savings can be achieved by reducing the duty cycle of the RFID reader and relying on its place in the RFID reader. secondary detector most of the time. The secondary detector could, by way of example and without limitation, be selected from the group comprised of passive infrared, inductive, capacitive, microwave or ultrasound detectors. In general, the secondary detector functions as a motion detector, since the changes it responds to are typically caused by the movement of objects that are not necessarily ID tags. A currently preferred secondary detector is a passive infrared detector designed to detect changes in the infrared background of the reader's detection field.
Energy savings could be optimized by limiting the operation of the RFID reader to approximately the period of time required to verify the presence of an ID tag, that is, to transmit a radio frequency interrogation signal, receive and decode a response from a ID tag if it is present in the detection field and, if an ID tag is detected, perform an access control function such as unlocking a door and then re-locking it. Upon termination of the tag reading function or the access control function, the tag reader outputs a disable or disconnect control signal to the power control switch to return the tag reader to the off state. standby power limited.
The invention also extends to a method of operating an identification tag reader having a detection field, comprising the steps of placing the identification tag reader in a standby or idle state, detecting insertion of an object in the detection field, activate or wake up the RF reader for a relatively short period of time that is at least sufficient to evoke a response from an identification tag if present in the detection field, and return the RF proximity reader to the standby state or sleep mode. The step of detecting could include detecting a change in a physical characteristic within the detection field such as a change in the position of an object that is not necessarily an ID tag within the detection field of the RFID reader. The change of position could be done by infrared, inductive, capacitive, ultrasonic or microwave detection. Brief description of the drawings
Figure 1 is a block diagram of a low power consumption radio frequency identification system in accordance with this invention.
Figure 2 presents a low power RFID reader system in accordance with this invention characterized by a secondary passive infrared detector; Y
Figure 3 is a diagram of a plan view of the low power RFID reader system of Figure 2, illustrating the RFID detection field and the passive infrared overlapping field of view.
Detailed description of the preferred embodiments
With reference to the accompanying drawing, Figure 1 shows in block diagram form a low power identification tag system generally designated with numbers. The reader system 10 includes a radio frequency tag reader 12 which could be any type of radio frequency reader, but, for reasons noted hereinbefore, this invention is particularly useful with proximity or passive RFID tag readers because at its highest power consumption in operation. The reader system 1 is supplied with electrical power for operation by an electrical power supply source 14 connected to the reader through a power control circuit or switch 16. The power supply source 14 could be power from an alternating current line (hereinafter ac), but will normally be a battery power source, since the main object of this invention is to enable practical battery operation of the system. reader 10.
The tag reader 12 has a radio frequency antenna 18, drawn with transparent lines in Figure 2, which emits an interrogation signal designed to evoke a response from the ID tags in sufficient proximity to the reader 12, and to receive an interrogation signal. radio frequency response from any of these ID tags. The antenna or antenna system of the tag reader 12 has a detection field S, represented by the concentric arcs in Figure 3, within which the ID reader is able to evoke a response from the ID tags and also receive the response. response signal from labels. Outside the detection field, the intensity of the interrogation signal may be insufficient to evoke a response, or, if a response is evoked, the strength of the response signal at antenna 18 is too weak to be read by the reader 12. The range of the tag reader 12 is not only limited in distance from the antenna, but the range may also vary with the
ES 2 284 497 T3 direction from the antenna, that is, the antenna could have a directional pattern with maximum sensitivity in a particular direction and decreasing sensitivity when moving away from that direction. The directionality of the tag reader could further be determined not only by the radiation pattern of the antenna, but also by the physical environment around the reader. If the reader system 10 is mounted on a wall W as in Figure 3, then the effective detection field S is limited to the area in front of that wall, because the ID tags will be present only in that area and not behind it. the wall, even though the card reader's RF field might actually extend through and behind the wall. Consequently, the detection field of the tag reader 12 is limited in range and direction by the radiation and reception patterns of radio frequency signals and by the physical environment around the reader system 10 as in Figures 2 and 3.
In accordance with this invention, a secondary detector 20 is provided having a field of view W that generally overlaps the detection field S of the RFID tag reader 12. The currently preferred secondary detector 20 is a passive infrared motion detector (hereinafter PIR detector) of the type commonly used in home security systems to turn on light in response to changes in the infrared background in the field of view. detector, such as movement of a person's body in front of the PIR detector. Detection of this type is today commercially available at low cost. In conventional applications, the PIR detector obtains an output signal that is typically used to trigger a security alarm or to switch lights.
When performed in accordance with this invention as the secondary detector 20, a PIR detector is arranged and positioned as in Figures 2 and 3 with respect to the RFID reader 12 in order to detect, for example, the presence of a hand that ripples an ID tag past the RDIF tag reader 12. The output signal of the secondary detector is connected as a ON control signal to the power control switch circuit 16.
In an initial standby state of tag reader 12, power control switch 16 is off to inactivate RFID reader 12. When a moving object, such as the hand of the holder of an ID tag, is detected by the secondary PIR detector 20, the resulting ON control signal from the secondary detector activates the power switch 16 to supply electrical power to the secondary detector. RFID reader 12 of power supply 14, thereby activating the RFID reader. In this now active state, the tag reader 12 operates in a conventional manner and transmits a radio frequency signal designed to evoke a radio frequency response from any ID tags within range of the reader, and listens for any radio frequency response from the ID tags. Typically, the tag reader 12 remains on only for the duration necessary to read an ID tag. If, after an appropriate time, the reader transmission has not evoked an ID tag response, the reader outputs an OFF control signal to the power control switch, thereby cutting off the power supply and returning to the power supply. reader to a standby state. If the secondary detector has actually detected the entry of the ID tag in the sensing field S, the tag reader 12 then executes an access control function to enable access to the protected facility, for example by opening an electrical interlock of door and returning the facility to an interlocked condition. Upon completion of the access control cycle, the reader outputs the DISCONNECT control signal to the power control switch and returns to a standby state. The tag reader 12 typically operates under the control of a microprocessor, and the output of the OFF control signal at the appropriate time is accomplished by appropriate programming of the microprocessor.
The power control switch 16 could be operated to suspend only some functions of the RFID reader instead of completely disconnecting power to the tag reader. It may not be desirable to completely disconnect the tag reader 12 because certain microprocessor initialization functions would require rerun after each power surge. For this reason, the CONNECT control signal could instead operate to request certain functions and subroutines from the microprocessor necessary to actively detect and read the ID tags, while keeping the microprocessor in a low-power state at the same time. tag reader wait state. That is, the standby state of the tag reader 12 is any state in which the tag reader's power consumption is limited to less than its normal operating requirements for detecting and reading ID tags.
The connection time of the RFID reader per ID tag could be quite short, or in the order of a few seconds, depending on the type of access that is being controlled. By limiting the connection time of the RFID reader in this mode, the duty cycle of the RFID reader, that is, the connection time of the RFID reader 12 relative to the operation time of the reader system 10, can be make very small, thereby greatly reducing the power consumption of the combined RFID / PIR system 10 and realizing practical battery operation of such combination readers. The combo reader 10 could be packaged for any portable or stationary application, in any housing that might suit practical and aesthetic considerations.
Passive infrared detectors consume little power compared to passive RFID detectors because the PIR detector does not emit a signal, but rather responds to the presence of radiation emitted by a warm object or body. However, the choice of a secondary detector is not limited to infrared detectors. Other motion detection technologies are available that could be adapted for the purposes of this invention. For example, inductive or capacitive type detectors could be implemented as secondary detector 16 to
ES 2 284 497 T3 detect the entry of an object into the detection field of the RFID reader by detecting changes in inductance or capacitance in the environment close to the reader. Similarly, ultrasonic and microwave detectors are available and can replace passive infrared detector 16. In general, a passive sensing technology such as inductive or capacitive will normally be preferred over an active technology such as ultrasonic or microwave motion detection, because passive detectors typically consume less electrical energy. To achieve greater sensitivity and reliability, multiple secondary detectors 16 could be installed and connected in an "OR" gate logic such that the RFID reader connects if any one of the multiple secondary detectors is activated. Multiple secondary detectors could also be connected in an "AND" gate logic such that the RFID reader is connected only if all secondary detectors are activated to reduce false activations of the reader.
While a presently preferred embodiment of the invention has been described and illustrated by way of example and for clarity, it should be understood that many changes, substitutions, and modifications thereof will be apparent to those skilled in the art without departing from the scope of the present invention as has been defined by the following claims.
Contents3
1 sheet
Sheet 1
20 members in 12 offices
Priority claims5
| Document | Office | Kind | Date |
|---|---|---|---|
| 19990299121 | United States of America | – | |
| 29912199 | United States of America | A | |
| 29912199 | United States of America | A | |
| 00928301299121 | – | – | – |
| US19990299121 | – | – | – |
Members20
| Document | Office | Kind | |
|---|---|---|---|
| CA2370848A1 | Canada | A1 | |
| WO0065551A1 | World Intellectual Property Organization (WIPO) | A1 | |
| AU4655900A | Australia | A | |
| US6150948A | United States of America | A | |
| EP1185962A1 | European Patent Office (EPO) | A1 | |
| ZA200109462B | South Africa | B | |
| HK1044210A1 | Hong Kong, China | A1 | |
| JP2002543646A | Japan | A | |
| CN1391686A | China | A | |
| AU761945B2 | Australia | B2 | |
| CN1145128C | China | C | |
| EP1185962A4 | European Patent Office (EPO) | A4 | |
| EP1185962B1 | European Patent Office (EPO) | B1 | |
| AT359577T | Austria | T | |
| ATE359577T1 | Austria | T1 | |
| DE60034335D1 | Germany | D1 | |
| HK1044210B | Hong Kong, China | B | |
| ES2284497T3This record | Spain | T3 | |
| DE60034335T2 | Germany | T2 | |
| CA2370848C | Canada | C |
Numbers
- Publication
- 2284497
- Publication, DOCDB
- 2284497
- Publication, EPODOC
- ES2284497T
- Application
- 928301
- Application, DOCDB
- 00928301
- Application, EPODOC
- ES20000928301T
Titles2
- Spanish
- LECTOR DE IDENTIFICACION DE RADIOFRACUENCIA DE BAJO CONSUMO DE ENERGIA.
- English
- LOW POWER CONSUMPTION RADIOFRACUENCE IDENTIFICATION READER.
Classification
- CPC, 5
- G06K7/10128
- G06K7/0008
- G06K7/10207
- Y02D30/70
- H04B5/77
- IPC, 6
- G06K17 00
- G08B23 00
- G06K7 00
- G09F3 00
- H04B1 59
- H04B5 48