CN100458841C

CN100458841C - Semi-active RFID tag supporting wireless charging

Info

Publication number: CN100458841C
Application number: CNB2006101481593A
Authority: CN
Inventors: 车文毅; 闫娜; 闵昊
Original assignee: Fudan University
Current assignee: Fudan University
Priority date: 2006-12-28
Filing date: 2006-12-28
Publication date: 2009-02-04
Anticipated expiration: 2026-12-28
Also published as: CN1996352A

Abstract

The invention relates to a half RF identification label. It realizes a half RF identification label supporting wireless charging function through changing the RF free identification label system composition with additional battery, energy inspection, energy selection and battery protection. Through two pole inspection method and the output DC level deciding the volume of the received energy, selecting the frequency energy received by the antenna or supplying power for the storage, processing and signal generation of the label by the battery. When the received frequency energy is strong, energy selection circuit will charge the battery using extra energy to extend the life of the label. It can also monitor the charging and power releasing process for the protection of battery.

Description

A kind of semi-active RFID tag of supporting wireless charging

Technical field

The invention belongs to the wireless communication technique field, specifically involve a kind of semi-active RFID tag.

Background technology

In our daily life, automatic identification technology has a very wide range of applications in fields such as commerce, service sectors.Survey and compare with bar code, magnetic stripe with Contact Type Ic Card, REID (RFID-Radio FrequencyIdentification) has numerous advantages such as noncontact, precision height, information gathering are handled rapidly, all weather operations, has obtained vigorous growth and use widely in recent years.In different application scenarios, the composition structure of radio-frequency recognition system can difference according to actual needs change, but no matter be in which application scenario, any one radio-frequency recognition system has all comprised read write line and two parts of transponder.Fig. 1 has provided the synoptic diagram of a typical radio-frequency recognition system of being made up of read write line (1), reading and writing device antenna (2), transponder antenna (3) and transponder (4).Different according to NE BY ENERGY TRANSFER and method for interchanging data, the coupling scheme between read write line and the transponder can be divided into two kinds of inductive coupling and electromagnetism back scattering couplings.According to the difference of working frequency range, can be divided into low frequency, high frequency, ultrahigh frequency and four frequency ranges of microwave again.In general, the inductive coupling mode is applicable to low frequency and high-frequency band, and its characteristics are and can work in rugged surroundings such as humidity, but operating distance is generally in one meter, and typical frequency of operation has 125kHz, 225kHz, 13.56MHz; And electromagnetism back scattering coupling scheme are applicable to ultrahigh frequency and microwave frequency band, can realize the signal transmission more than a meter, and typical frequency of operation has 433MHz, 868MHz, 915MHz, 2.45GHz and 5.8GHz.

In actual applications, transponder often is called as radio-frequency (RF) tag or electronic tag (abbreviation label).According to the difference of tag-powered mode, can be divided into passive (Passive), half active (Semi-passive or Battery assisted passive) and active (Active) three kinds is dissimilar.Passive label does not have powered battery, and it is provided by the radio-frequency (RF) energy that read write line sends with the energy of keeping data storage, processing, signal generation fully in order to carry out data communication.Battery is equipped with in semi-active label inside, label optionally uses the radio-frequency (RF) energy of read write line emission or the energy of battery that the circuit that label inside is used for data storage, processing and internal signal generation is powered according to the energy size that receives, and is still provided by the radio-frequency (RF) energy of read write line emission in order to the energy that carries out data communication in the label.All required during active label work energy are supplied with by internal cell fully, and label can initiatively outwards send communication request, is often used for the function that realizes that some are complicated.Compare with passive label, semi-active label can be used for realizing the wireless telecommunications of farther distance because littler to the demand of the radio-frequency (RF) energy that receives; Compare with active label, the circuit structure of semi-active label is simple, and also littler for the demand of battery performance, production cost is lower.These advantages of semi-active label provide wide application space for it at numerous areas such as logistics, storage, car and boat monitoring, import and export checks.

Summary of the invention

The objective of the invention is to propose a kind of semi-active RFID tag of supporting wireless charging, reducing the demand of tag system, thereby realize the wireless telecommunications of farther distance for the energy that receives read write line emission.

The semi-active RFID tag of the support wireless charging that the present invention proposes is formed by the part system that changes passive label, and increases modules such as battery, energy measuring, energy selection and battery protection therein.Fig. 2 has provided structured flowchart of the present invention.It comprises antenna 5, battery 6, rectification and load-modulate module 7, battery protection module 8, energy detection module 9, energy selection module 10 and carries out circuit 11 these seven parts of functions such as data storage, processing and signal generation.Modules such as core of the present invention is that energy provides in the system, energy measuring and energy selection.Rectification and load-modulate module 7 are recovered out with the radiofrequency signal that obtains in the antenna 5, form galvanic current and press.When the RFID tag range reader is near, the energy height that antenna 5 receives, thereby the voltage height that rectification goes out; When the radio-frequency (RF) tag range reader was distant, the voltage that rectification goes out was low.Energy detection module 9 is according to rectification and load-modulate module 7 output voltage V _RHeight judge the size that receives energy on the antenna 5, control energy selects module 10 to select V _RPerhaps battery 6 power supply V _RBe used as in the tag system power supply V in order to the circuit 11 of functions such as storage, deal with data and signal generation _DD

Fig. 3 has provided the structural diagrams of energy detection module 9 and energy selection module 10.Owing to carry out accurate voltage detecting and need use the bigger circuit of power consumption such as reference voltage source and voltage comparator,, can shorten the maximum reading/writing distance of radio-frequency recognition system if the energy that receives with antenna 5 is powered to this part circuit fully.Therefore, the mode that the present invention proposes a kind of two-stage energy measuring solves this problem.Be that energy detection module 9 comprises elementary detection module 14 and accurate detection module 15, elementary testing circuit 14 uses the radio-frequency (RF) energy power supply, it adopts the minimum electrify restoration circuit of quiescent dissipation to carry out preliminary energy measuring, when it detects energy on the antenna 5 when enough strong, export a wake-up signal V _WakeWith K switch ₃16 conductings.At this moment, use battery 6 power supply V _B Accurate testing circuit 15 once more to V _RSize detect, the result of detection will be by control line K ₁C and K ₂C is sent to energy and selects module 10 gauge tap K ₁12 and K ₂13 conducting or shutoff, thus carry out the switch and the switching of energy.If the energy that receives on the antenna 5 also has outside the operate as normal of tag system is provided when more than needed, this part energy more than needed will be used for battery 6 is charged, thereby make label to reuse for a long time and need not often change battery 6.

Battery protection module 8 is in order to detecting the voltage and current of battery 6 in charge and discharge process, in case stopcock K immediately occurred overcharging, after mistake is put or electric current the is excessive situation ₂13, protection battery 6 is not damaged, and simultaneously, label sends alerting signal to read write line.

Description of drawings

Fig. 1 is the structural diagrams of radio-frequency recognition system.

Fig. 2 is the structural diagrams of semi-active RFID tag.

Fig. 3 is the structural diagrams that energy detection module 9 and energy are selected module 10.

Fig. 4 is a physical circuit of the present invention.

Fig. 5 is the structural diagrams of accurate testing circuit 15 in the energy detection module 9.

Number in the figure: 1 is read write line, and 2 is reading and writing device antenna, and 3 is transponder antenna; 4 is transponder, and 5 is antenna, and 6 is battery; 7 are rectification and load-modulate module, and 8 is the battery protection module, and 9 is energy detection module; 10 are energy selection module, and 11 is data storage; functional circuit module such as processing and signal generation, 12 is gauge tap K1; 13 is gauge tap K2, and 14 is elementary detection module, and 15 is accurate detection module; 16 is K switch 3; 17 is reference voltage source, and 18 are voltage stabilizing and filtering circuit, and 19 is bleeder circuit; 20 is voltage comparator; 21 is logical circuit, and 22 is wave detector, and 23 is biasing circuit; 24 is low dropout voltage regulator; 25 is ring oscillator, and 26 is level shift and driving circuit, and 27 is electrify restoration circuit; 28 is non-volatility memorizer and control circuit thereof, and 29 is digital baseband.

Embodiment

Below by an instantiation the present invention is described in further detail.

Fig. 4 has provided the system construction drawing of a complete semi-active label.Wherein, functional circuit 11 is connected to form through circuit by ring oscillator amount 25, level shift and driving circuit 26, electrify restoration circuit 27, non-volatility memorizer and the control circuit 28 thereof of biasing circuit 23, low dropout voltage regulator amount 24, belt current biasing and digital baseband 29.When label entered into the on-site of read write line electromagnetic field, rectification and load-modulate module 7 reverted to a DC voltage V with the radio-frequency (RF) energy on the antenna 5 _R, the elementary testing circuit 14 in the energy detection module 9 is subjected to this voltage V _RExcitation after, export a wake-up signal V _WakeWith K switch ₃16 conductings, accurately testing circuit 15 is started working.As shown in Figure 5, accurately testing circuit 15 is connected to form by filter circuit of pressure-stabilizing 18, reference voltage source 17, bleeder circuit 19, voltage comparator 20 and logical circuit 21 circuit successively.Wherein, bleeder circuit 19 comprises several divider resistances (being R1-R3 among the figure).Accurately testing circuit 15 is at first used voltage stabilizing and 18 couples of V of filtering circuit _RStablize, get wherein two specific intermediate level V with bleeder circuit 19 then ₁And V ₂Fixed reference level V with reference voltage source 17 outputs _CmpCompare.Distance between read write line and label is far, the radio-frequency (RF) energy that antenna 5 receives very hour, the DC level V of rectification and 7 outputs of load-modulate module _RVery low, V ₁And V ₂All less than V _CmpSo, the output V of voltage comparator 20 _XAnd V _YBe low level, after logical circuit 21 is handled this comparative result, export two signal K ₁C and K ₂C stopcock energy is selected the K in the module 10 ₁12 and K ₂13, control K simultaneously ₃C turn-offs the supply access of himself, and provides the unlatching threshold that feedback signal Logic_Back requires to improve elementary testing circuit 14.When the energy that receives on the antenna 5 is enough to keep communication between read write line and the label and needs, V _RRaise, cause V ₁Less than V _CmpAnd V ₂Greater than V _CmpSo, the output V of voltage comparator 20 _XBe low level, and V _YBe high level, after logical circuit 21 is handled this comparative result, with K switch ₂13 open, and power in 6 pairs of tag systems of battery.Further shorten the distance between read write line and the label, when the energy that receives on the antenna 5 is enough to provide whole tag system to be worked, the output V of bleeder circuit 19 ₁And V ₂All greater than V _CmpSo, the output V of voltage comparator _XAnd V _YBe high level, after logical circuit 21 is handled this comparative result, export two signals K switch ₁12 and K ₂13 all conductings, this moment, the energy of tag system was provided by the radio-frequency (RF) energy that obtains on the antenna 5, and label enters passive mode.In K switch ₁12 and K ₂13 all under the situation of conducting, if the distance between read write line and the label is very short, when the energy that receives on the antenna 5 was very strong, the output of rectification and load-modulate module 7 will also be charged to battery 6 with unnecessary energy when providing energy for tag system.

In tag system shown in Figure 4, as long as energy selects module 10 to select V _RAnd V _BIn any one export V as it _DD, label promptly enters duty.The envelope signal that wave detector 22 takes out on the antenna 5 converts thereof into digital signal Data; Biasing circuit 23 and low dropout voltage regulator 24 provide current reference I for the ring oscillator 25 of belt current biasing _RefWith voltage reference V _RefThereby, obtain the signal of frequency stabilization, after handling through level shift and driving circuit 26, this signal becomes the clock signal C lock of system; Electrify restoration circuit 27 provides a power-on reset signal POR.In addition, biasing circuit 23 also provides a current offset signal I for non-volatility memorizer 28 _BiasDigital baseband 29 is handled above-mentioned Data, Clock, POR according to the regulation of communication protocol, simultaneously, finish communication with non-volatility memorizer by control bus and data bus, final signal processing results coding back (Mod) is transferred to rectification and load-modulate module 7, change the input impedance of tag system with it, the mode that adopts the electromagnetism back scattering to be coupled realizes the communication between label and the read write line.

In the above-mentioned course of work of tag system, in case energy is selected the K switch in the module 10 ₂13 conductings, battery 6 enters charging and discharging circuit, and battery protection module 8 promptly is waken up, and begins to detect the voltage and current of battery 6 in charge and discharge process.If abnormal conditions have appearred in the work of battery 6, stopcock K at once ₂13; battery 6 is protected, exported the alerting signal that a battery 6 is made mistakes simultaneously, give the digital baseband 29 in the label together with the state (voltage, electric current, dump energy etc.) of battery 6; digital baseband 29 is transferred to read write line with alerting signal after this signal is encoded.

Claims

1, a kind of semi-active RFID tag of supporting wireless charging is characterized in that it comprises that antenna (5), battery (6), rectification and load-modulate module (7), battery protection module (8), energy detection module (9), energy select module (10) and carry out these seven parts of circuit (11) of data storage, processing and signal generation function; Rectification and load-modulate module (7) are recovered out with the radiofrequency signal that obtains in the antenna (5), form galvanic current and press; Energy detection module (9) is according to rectification and load-modulate module (7) output voltage V _RHeight judge the size that receives energy on the antenna (5), control energy selects module (10) to select V _RPerhaps battery (6) power supply V _BBe used as in the tag system power supply V in order to the circuit (11) of storage, deal with data and signal generation function _DD

2, the semi-active RFID tag of support wireless charging according to claim 1 is characterized in that energy detection module (9) comprises elementary detection module (14) and accurate detection module (15); Elementary detection module (14) uses the radio-frequency (RF) energy power supply, and it adopts the minimum electrify restoration circuit of quiescent dissipation to carry out preliminary energy measuring, when the energy intensity on detecting antenna (5) satisfies whole tag system job requirement, exports a wake-up signal V _WakeWith K switch ₃(16) conducting; At this moment, use battery (6) power supply V _BAccurate detection module (15) once more to V _RSize detect, the result of detection is by control line K ₁C and K ₂C is sent to energy and selects module (10) gauge tap K ₁(12) and K ₂(13) conducting or shutoff, thus carry out the switch and the switching of energy.

3, the semi-active RFID tag of support wireless charging according to claim 1 is characterized in that carrying out data storage, processing and signal generation functional circuit (11) and is connected to form through circuit by ring oscillator amount (5), level shift and driving circuit (26), electrify restoration circuit (27), non-volatility memorizer and control circuit (28) thereof and the digital baseband (29) of biasing circuit (23), low dropout voltage regulator amount (4), belt current biasing.

4, the semi-active RFID tag of support wireless charging according to claim 2 is characterized in that accurate detection module (15) is connected to form by filter circuit of pressure-stabilizing (18), reference voltage source (17), bleeder circuit (19), voltage comparator (20) and logical circuit (21) circuit successively.