CN103455838A - RFID tag with magnetic sensing device, RFID system and magnetic field intensity detection method - Google Patents
RFID tag with magnetic sensing device, RFID system and magnetic field intensity detection method Download PDFInfo
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- CN103455838A CN103455838A CN2012101836261A CN201210183626A CN103455838A CN 103455838 A CN103455838 A CN 103455838A CN 2012101836261 A CN2012101836261 A CN 2012101836261A CN 201210183626 A CN201210183626 A CN 201210183626A CN 103455838 A CN103455838 A CN 103455838A
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Abstract
The invention provides an RFID tag with a magnetic sensing device, an RFID system and a magnetic field intensity detection method. A chip of the RFID tag is provided with two pins, the magnetic sensing device and an antenna of the RFID tag form a parallel connection structure, a logic circuit for on-off state controlling is arranged on a connection circuit of the magnetic sensing device and the chip of the RFID tag, and the connection circuit and the logic circuit for on-off state controlling are one part of the chip. When the logic circuit is disconnected, the magnetic sensing device is not in parallel connection with the antenna, and after the magnetic sensing device is placed in certain magnetic field intensity for a period of time, the first resonant frequency and the signal intensity of the antenna keep unchanged; when the logic circuit is connected, the magnetic sensing device is in parallel connection with the antenna, and after the magnetic sensing device is placed in certain magnetic field intensity for a period of time, the antenna works under the second resonant frequency. The RFID tag receives a command sent by an RFID reader to control the on-off state of the logic circuit, and therefore, changes of a magnetic field are detected by comparing differences of signal intensity of different frequencies of the antenna. According to the RFID tag with the magnetic sensing device, the RFID system and the magnetic field intensity detection method, magnetic field changes can be detected at low cost.
Description
Technical field
The present invention relates to RFID (Radio Frequency Identification, radio-frequency (RF) identification) technical field, relate in particular to a kind of label of the RFID with magnetically sensitive device, rfid system and magnetic field detection method.
Background technology
In recent years, rfid system had become more prevalent.Rfid system is mainly used in the identification to people and thing.In general, this system at least comprises a RFID reader, and the radiofrequency signal from one or more RFID labels can be launched and accept to this RFID reader in the scope of a setting.This RFID label generally is encapsulated, and can be attached on an object, and it comprises the microchip that an energy and antenna carry out information interchange.This microchip is an integrated circuit in general, and it can be used for storing and process information, the modulation /demodulation radiofrequency signal, and can move other specific function.The antenna of RFID label is for receiving and sending radiofrequency signal, and usually is applicable to a kind of special frequency.
In some equipment, when the magnetic field that has been used to monitor product environment of living in the rfid system of magnetically sensitive device has surpassed acceptable magnetic field.In general these equipment requirement induction installations will have a lasting energy source, are used for detecting the change in magnetic field, but this can increase the cost of equipment.In addition, some equipment requirement induction installations also will be connected with a comparator circuit, thereby detect the degree size that departs from reference voltage, and this requirement has increased the cost of equipment greatly.In a word, improve rfid system and be necessary, it requires can be used for detecting when not using lasting energy source or using a kind of adjunct circuit cheaply changes of magnetic field.
Summary of the invention
The embodiment of the present invention provides a kind of label of the RFID with magnetically sensitive device, rfid system and magnetic field detection method, detects at lower cost changes of magnetic field.
On the one hand, the embodiment of the present invention provides a kind of label of the RFID with magnetically sensitive device, and two pins are arranged on the chip of described RFID label, two pins of described magnetically sensitive device and this are connected, and form parallel-connection structure with the antenna of described RFID label, the variation of external magnetic field intensity can cause the variation of the resistance of magnetically sensitive device own, a logical circuit of controlling break-make is arranged on the circuit be connected with the chip of RFID label at described magnetically sensitive device, the circuit of this connection is the part of chip with the logical circuit of controlling break-make, the break-make of logical circuit determined magnetically sensitive device whether with the sky line parallel: when logical circuit disconnects, magnetically sensitive device not with the sky line parallel, after now being placed on certain lower a period of time of magnetic field intensity, the first resonant frequency and the signal intensity of antenna remain unchanged, when logical circuit is connected, magnetically sensitive device and a day line parallel, now be placed on certain magnetic field intensity after a period of time, and the characteristic frequency of antenna and signal intensity at least have one and change, and now antenna is operated under the second resonant frequency, described RFID label receives the break-make of the instruction of RFID reader transmission with control logic circuit, thereby realizes detecting from the difference between the signal intensity of the different frequency of antenna by comparison the change of magnetic field intensity.
Optionally, in an embodiment of the present invention, the antenna of described RFID label is monopole antenna.
Optionally, in an embodiment of the present invention, the antenna of described RFID label is double-doublet antenna: described magnetically sensitive device forms parallel-connection structure with antenna wherein; Perhaps described magnetically sensitive device and two antennas form parallel-connection structure simultaneously.
Optionally, in an embodiment of the present invention, described magnetically sensitive device is the resistor-type magnetically sensitive device, and described magnetically sensitive device comprises: magnetoresistive element and other magneto-resistance type devices.
On the other hand, the embodiment of the present invention provides a kind of label of the RFID with magnetically sensitive device, and a pin is arranged on the chip of described RFID label, one end of described magnetically sensitive device is connected with this pin, the other end is connected on the antenna of described RFID label, and form parallel-connection structure with antenna, the variation of external magnetic field intensity can cause the variation of the resistance of magnetically sensitive device own, a logical circuit of controlling break-make is arranged on the circuit be connected with the chip of RFID label at described magnetically sensitive device, the circuit of this connection is the part of chip with the logical circuit of controlling break-make, the break-make of logical circuit determined magnetically sensitive device whether with the sky line parallel: when logical circuit disconnects, magnetically sensitive device not with the sky line parallel, after now being placed on certain lower a period of time of magnetic field intensity, the first resonant frequency and the signal intensity of antenna remain unchanged, when logical circuit is connected, magnetically sensitive device and a day line parallel, after now being placed on certain lower a period of time of magnetic field intensity, the characteristic frequency of antenna and signal intensity at least have one and change, and now antenna is operated under the second resonant frequency, described RFID label receives the break-make of the instruction of RFID reader transmission with control logic circuit, thereby realizes detecting from the difference between the signal intensity of the different frequency of antenna by comparison the change of magnetic field intensity.
Optionally, in an embodiment of the present invention, the antenna of described RFID label is monopole antenna.
Optionally, in an embodiment of the present invention, the antenna of described RFID label is double-doublet antenna: described magnetically sensitive device forms parallel-connection structure with antenna wherein; Perhaps described magnetically sensitive device and two antennas form parallel-connection structure simultaneously.
Optionally, in an embodiment of the present invention, described magnetically sensitive device is the resistor-type magnetically sensitive device, and described resistor-type magnetically sensitive device comprises: magnetoresistive element and other magneto-resistance type devices.
Another aspect, the embodiment of the present invention provides a kind of label of the RFID with magnetically sensitive device, described magnetically sensitive device is connected on the antenna of described RFID label, and form parallel-connection structure with antenna, the variation of external magnetic field intensity can cause the variation of the resistance of magnetically sensitive device own, a logical circuit of controlling break-make is arranged on the circuit be connected with antenna at described magnetically sensitive device, the circuit of this connection is the part of chip with the logical circuit of controlling break-make, the break-make of logical circuit determined magnetically sensitive device whether with the sky line parallel: when logical circuit disconnects, magnetically sensitive device not with the sky line parallel, now be placed on certain magnetic field intensity after lower a period of time of level, the first resonant frequency and the signal intensity of antenna remain unchanged, when logical circuit is connected, magnetically sensitive device and a day line parallel, now be placed on certain magnetic field intensity after lower a period of time of level, and the characteristic frequency of antenna and signal intensity at least have one and change, and now antenna is operated under the second resonant frequency, described RFID label receives the break-make of the instruction of RFID reader transmission with control logic circuit, thereby realizes detecting from the difference between the signal intensity of the different frequency of antenna by comparison the change of magnetic field intensity.
Optionally, in an embodiment of the present invention, the antenna of described RFID label is monopole antenna.
Optionally, in an embodiment of the present invention, the antenna of described RFID label is double-doublet antenna: described magnetically sensitive device forms parallel-connection structure with antenna wherein; Perhaps described magnetically sensitive device and two antennas form parallel-connection structure simultaneously.
Optionally, in an embodiment of the present invention, described magnetically sensitive device is the resistor-type magnetically sensitive device, and described resistor-type magnetically sensitive device comprises: magnetoresistive element and other magneto-resistance type devices.
On the one hand, the embodiment of the present invention provides a kind of rfid system with magnetically sensitive device again, and described rfid system comprises RFID label and RFID reader, and described RFID label comprises the above-mentioned label of the RFID with magnetically sensitive device; Described RFID reader sends the break-make of instruction with the logical circuit of control RFID label, thereby detects the change of magnetic field intensity from the difference between the signal intensity of the different frequency of antenna by comparison.
Again on the one hand, the embodiment of the present invention provides a kind of magnetic field intensity detection method of the rfid system with magnetically sensitive device, described magnetic field intensity detection method is applied to the above-mentioned rfid system with magnetically sensitive device, comprising: by described RFID reader, send the break-make of instruction with the logical circuit of control RFID label; Receive the break-make of the instruction of RFID reader transmission with control logic circuit by the RFID label: when logical circuit disconnects, magnetically sensitive device not with the sky line parallel, now be placed under certain magnetic field intensity, the first resonant frequency and the signal intensity of antenna remain unchanged; When logical circuit is connected, magnetically sensitive device and a day line parallel, now be placed under certain magnetic field intensity, and the characteristic frequency of antenna and signal intensity at least have one and change, and now antenna is operated under the second resonant frequency; Utilize the comparison of described RFID reader to detect the change of magnetic field intensity from the difference between the signal intensity of the different frequency of antenna.
Technique scheme has following beneficial effect: because on the chip of employing RFID label, two pins are arranged; The antenna of magnetically sensitive device and RFID label forms parallel-connection structure, a logical circuit of controlling break-make is arranged on the circuit be connected with the chip of RFID label at magnetically sensitive device, the circuit of this connection is the part of chip with the logical circuit of controlling break-make: when logical circuit disconnects, magnetically sensitive device not with the sky line parallel, after now being placed on certain lower a period of time of magnetic field intensity, the first resonant frequency and the signal intensity of antenna remain unchanged; When logical circuit is connected, magnetically sensitive device and a day line parallel, after now being placed on certain lower a period of time of magnetic field intensity, now antenna is operated under the second resonant frequency; The RFID label receives the break-make of the instruction of RFID reader transmission with control logic circuit, thereby realize detecting from the difference between the signal intensity of the different frequency of antenna by comparison the technological means of the change of magnetic field intensity, so reached the technique effect that detects at lower cost changes of magnetic field, and the energy that utilizes RFID to obtain, solved the powerup issue of magnetic field detection.
The accompanying drawing explanation
In order to be illustrated more clearly in the embodiment of the present invention or technical scheme of the prior art, below will the accompanying drawing of required use in embodiment or description of the Prior Art be briefly described, apparently, accompanying drawing in the following describes is only some embodiments of the present invention, for those of ordinary skills, under the prerequisite of not paying creative work, can also obtain according to these accompanying drawings other accompanying drawing.
Fig. 1 is the schematic diagram that embodiment of the present invention magnetically sensitive device is connected with the RFID label chip;
The equivalent circuit diagram that Fig. 2 is RFID label chip inside antenna;
Fig. 3 is the schematic diagram that embodiment of the present invention magnetically sensitive device, logic switch are connected with RFID label chip inside antenna equivalent electrical circuit;
Fig. 4 is the schematic diagram that embodiment of the present invention magnetically sensitive device directly is connected with the RFID label antenna;
The structure key diagram that Fig. 5 is embodiment of the present invention magnetically sensitive device;
The process flow diagram that Fig. 6 is the magnetic field intensity detection method of the embodiment of the present invention based on signal intensity.
Embodiment
Below in conjunction with the accompanying drawing in the embodiment of the present invention, the technical scheme in the embodiment of the present invention is clearly and completely described, obviously, described embodiment is only the present invention's part embodiment, rather than whole embodiment.Embodiment based in the present invention, those of ordinary skills, not making under the creative work prerequisite the every other embodiment obtained, belong to the scope of protection of the invention.
The magnetically sensitive device of the embodiment of the present invention is connected and at least has three kinds of situations with the chip of RFID label:
The two pins structure:
The embodiment of the present invention is a kind of device, system and technology that is used for detecting changes of magnetic field.This system has comprised a RFID label, and two pins are arranged on the chip of this RFID label.Two pins of magnetically sensitive device and this are connected, and with antenna, form parallel-connection structure.The variation of external magnetic field can cause the variation of the resistance of magnetically sensitive device own.A logical circuit of controlling break-make is arranged on the circuit be connected with chip at pin, and the circuit of this connection is the part of chip with the logical circuit of controlling break-make.
The break-make of logical circuit determined magnetically sensitive device whether with the sky line parallel.When logical circuit disconnects, magnetically sensitive device not with the sky line parallel, after now being placed on certain lower a period of time of magnetic field intensity, the first resonant frequency and the signal intensity of antenna remain unchanged.When logical circuit is connected, magnetically sensitive device and a day line parallel, after now being placed on certain lower a period of time of magnetic field intensity, the characteristic frequency of antenna and signal intensity at least have one and change, and now antenna is operated under the second resonant frequency.The RFID reader can send the break-make of instruction control logic circuit to label, when logical circuit is connected, can detect by comparison the change in magnetic field from the difference between the signal intensity of the different frequency of antenna.
With regard to an example, this system has comprised a RFID label, only has an antenna on this label.Two pins are arranged on the chip of this label.Two pins of magnetically sensitive device and this are connected, and with this root antenna, form parallel-connection structure.A logical circuit of controlling break-make is arranged on the circuit be connected with chip at pin, and the logical circuit of the circuit of this connection and control break-make is the part of chip.The variation of external magnetic field can cause the variation of the resistance of magnetically sensitive device own.
Be placed on certain lower a period of time of magnetic field intensity when logical circuit is connected after, the characteristic frequency of antenna and signal intensity at least have one and change, and now antenna is operated under the second resonant frequency.The RFID reader can send instruction to label, and the difference between the signal intensity of the different frequency during by the Compare Logic connecting and disconnecting of the circuit can detect the change in magnetic field.Or rather, magnetically sensitive device should have lower resistance, and its instantiation comprises: magnetoresistive element and other magneto-resistance type devices etc.
With regard to another example, this system has comprised a RFID label, and two antennas are arranged on this label.Two kinds of situations are now arranged.The first situation is that two pins of magnetically sensitive device and this are connected, and with first antenna, forms parallel-connection structure.A logical circuit of controlling break-make is arranged on the circuit be connected with chip at pin, and the logical circuit of the circuit of this connection and control break-make is the part of chip.The variation of external magnetic field can cause the variation of the resistance of magnetically sensitive device own.And second antenna is all the time with the first resonant frequency proper communication.
When logical circuit is connected, after being placed on certain lower a period of time of magnetic field intensity, the characteristic frequency of first antenna and signal intensity have at least a meeting to change, and it is operated under the second resonant frequency.The RFID reader can send instruction to label, and the difference between the signal intensity of the different frequency of first and second antennas can detect the change in magnetic field while connecting by the Compare Logic circuit.Difference between the signal intensity of different frequency during logical circuit break-make by second antenna self relatively also can detect the change in magnetic field.
The second situation is that two pins of magnetically sensitive device and this are connected, and with two antennas, form parallel-connection structure simultaneously.A logical circuit of controlling break-make is arranged on the circuit be connected with chip at pin, and the logical circuit of the circuit of this connection and control break-make is the part of chip.The variation of external magnetic field can cause the variation of the resistance of magnetically sensitive device own.This and the label only situation containing an antenna are similar.Be placed on certain lower a period of time of magnetic field intensity when logical circuit is connected after, antenna features frequency and signal intensity at least have one and change, and it is operated under the second resonant frequency.The RFID reader can send instruction to label, and the difference between the signal intensity of the different frequency during by the Compare Logic connecting and disconnecting of the circuit can detect the change in magnetic field.The first situation circuit connects fairly simple, and during work, the resonant frequency of two antennas may be different, can affect the precision of measurement.The second situation circuit connects more complicated, but the resonant frequency of two antennas is consistent during work, and measuring accuracy is higher.Or rather, magnetically sensitive device should have lower resistance, and its instantiation comprises: magnetoresistive element and other magneto-resistance type devices etc.
One pin configuration:
The chip of this label can only have a pin, and this pin outwards is connected with an end of magnetically sensitive device, and the other end of magnetically sensitive device is directly linked on antenna.Pin is similar in the situation of the tie point of chip internal and two pins, finally remains the purpose that will reach with the sky line parallel.A logical circuit of controlling break-make is arranged on the circuit be connected with the chip internal circuit at pin simultaneously.When logical circuit disconnects, magnetically sensitive device not with the sky line parallel, after now being placed on certain lower a period of time of magnetic field intensity, the first resonant frequency and the signal intensity of antenna remain unchanged.
When logical circuit is connected, magnetically sensitive device and a day line parallel, after now being placed on certain lower a period of time of magnetic field intensity, antenna features frequency and signal intensity at least have one and change, and it is operated under the second resonant frequency.The RFID reader can send the break-make of instruction control logic circuit to label, when logical circuit is connected, can detect by comparison the change in magnetic field from the difference between the signal intensity of the different frequency of antenna.
With regard to an example, this system has comprised a RFID label, only has an antenna on this label.A pin is arranged on the chip of this label.Magnetically sensitive device is connected with this pin, and the magnetically sensitive device other end is directly linked on antenna, with antenna, forms parallel-connection structure.A logical circuit of controlling break-make is arranged on the circuit be connected with chip at pin, and the logical circuit of the circuit of this connection and control break-make is the part of chip.The variation of external magnetic field can cause the variation of the resistance of magnetically sensitive device own.
Be placed on certain lower a period of time of magnetic field intensity when logical circuit is connected after, antenna is operated under the second resonant frequency, and its characteristic frequency and signal intensity at least have one and change.The RFID reader can send instruction to label, and the difference between the signal intensity of the different frequency during by the Compare Logic connecting and disconnecting of the circuit can detect the change in magnetic field.Or rather, magnetically sensitive device should have lower resistance, and its instantiation comprises: magnetoresistive element and other magneto-resistance type devices etc.
With regard to another example, this system has comprised a RFID label, and two antennas are arranged on this label.A pin is arranged on the chip of this label.Magnetically sensitive device is connected with this pin, and the magnetically sensitive device other end is directly linked on antenna, with first antenna, forms parallel-connection structure.A logical circuit of controlling break-make is arranged on the circuit be connected with chip at pin, and the logical circuit of the circuit of this connection and control break-make is the part of chip.The variation of external magnetic field can cause the variation of the resistance of magnetically sensitive device own.And second antenna is all the time with the first resonant frequency communication.
When logical circuit is connected, after being placed on certain lower a period of time of magnetic field intensity, first antenna is operated under the second resonant frequency, and its characteristic frequency and signal intensity have at least a meeting to change.The RFID reader can send instruction to label, and the difference between the signal intensity of the different frequency of first and second antennas can detect the change in magnetic field while connecting by the Compare Logic circuit.Difference between the signal intensity of different frequency during logical circuit break-make by first antenna self relatively also can detect the change in magnetic field.Or rather, magnetically sensitive device should have lower resistance, and its instantiation comprises: magnetoresistive element and other magneto-resistance type devices etc.
Without pin configuration:
While on the chip of RFID label, there is no pin, magnetically sensitive device can directly be linked on antenna.In this case, the antenna be connected with magnetically sensitive device can not break away from magnetically sensitive device and with normal frequency for communication.After being placed on certain lower a period of time of magnetic field intensity, the characteristic frequency of antenna and signal intensity at least have one and change.The RFID reader can send instruction to label apparatus, detects the change in magnetic field from the difference between the signal intensity of the different frequency of antenna by comparison.
With regard to an example, this system has comprised a RFID label, and two antennas are arranged on this label.Magnetically sensitive device directly is connected with first antenna, and second antenna is not connected with magnetically sensitive device all the time with the first resonant frequency proper communication.After being placed on certain lower a period of time of magnetic field intensity, first antenna is operated under the second resonant frequency, and its characteristic frequency and signal intensity have at least a meeting to change, and the characteristic frequency of second antenna and signal intensity are constant.The RFID reader can send instruction to label, and can detect the change in magnetic field by the difference between the signal intensity of the different frequency of first and second antennas relatively.Or rather, magnetically sensitive device should have lower resistance, and its instantiation comprises: magnetoresistive element and other magneto-resistance type devices etc.
In the same way, can be with on the chip of antenna also and can not be with pin, can be with one also can be with a plurality of pins.The radical of antenna can be one, two or even many.Also can connect one or more magnetically sensitive devices accordingly, the model of magnetically sensitive device can be the same or different simultaneously.With regard to a kind of instantiation of device, after being placed on certain lower a period of time of magnetic field intensity, the characteristic frequency of the antenna be connected with magnetically sensitive device and signal intensity have at least a meeting to change.The RFID reader can send instruction to label apparatus, detects the change in magnetic field from the difference between the signal intensity of the different frequency of antenna by comparison.
With regard to a kind of instantiation of magnetically sensitive device, the method for simultaneous comparison numerical value comprises that relatively numerical value and most signal strength values compare by these.These signal strength values belong to different frequencies, and interrelate with most magnetic field values, simultaneously based on above-mentioned mention relatively can detect the level in magnetic field.
Yet, with regard to another aspect, a rfid system comprises a RFID label apparatus and a RFID reader device.This RFID label apparatus is used to send two kinds of signals, signal when signal when above-mentioned logical circuit disconnects and logical circuit are connected, and these two kinds of signals have at least a kind of meeting to respond to the request be subject to.The RFID reader device is used for the RFID label apparatus is at least sent to a request.Fiducial value between signal strength values when reading device being installed being signal strength values in order accepting to connect from the logical circuit of label and logical circuit and to disconnect, and these fiducial values are converted into to the varying level in magnetic field.
In an example, the antenna of RFID label is connected with magnetically sensitive device, and a logical circuit of controlling break-make is arranged on this connection line.In logical circuit break-make whether two kinds of situations, from antenna, have corresponding with it two kinds of different frequencies.After logical circuit is connected and this label apparatus is positioned over to certain lower a period of time of magnetic field intensity, due to the variation of resonant frequency, will produce the intensity level of two kinds of unlike signals.
In an example, the RFID label apparatus comprises first, second two antennas, first antenna transmission first signal wherein, and second antenna transmission secondary signal.Better, first antenna is connected with magnetically sensitive device, after this label apparatus is placed on certain lower a period of time of magnetic field intensity, due to the variation of resonant frequency, will produce the different of secondary signal intensity level and first signal intensity level.
On the one hand, the embodiment of the present invention provides a kind of rfid system with magnetically sensitive device again, and described rfid system comprises RFID label and RFID reader, and described RFID label comprises the above-mentioned label of the RFID with magnetically sensitive device; Described RFID reader sends the break-make of instruction with the logical circuit of control RFID label, thereby detects the change of magnetic field intensity from the difference between the signal intensity of the different frequency of antenna by comparison.
Again on the one hand, the embodiment of the present invention provides a kind of magnetic field intensity detection method of the rfid system with magnetically sensitive device, described magnetic field intensity detection method is applied to the above-mentioned rfid system with magnetically sensitive device, comprising: by described RFID reader, send the break-make of instruction with the logical circuit of control RFID label; Receive the break-make of the instruction of RFID reader transmission with control logic circuit by the RFID label: when logical circuit disconnects, magnetically sensitive device not with the sky line parallel, now be placed under certain magnetic field intensity, the first resonant frequency and the signal intensity of antenna remain unchanged; When logical circuit is connected, magnetically sensitive device and a day line parallel, now be placed under certain magnetic field intensity, and the characteristic frequency of antenna and signal intensity at least have one and change, and now antenna is operated under the second resonant frequency; Utilize the comparison of described RFID reader to detect the change of magnetic field intensity from the difference between the signal intensity of the different frequency of antenna.
The schematic diagram of the magnetic induction label 10 be connected with the RFID label chip for embodiment of the present invention magnetically sensitive device as shown in Figure 1.In Fig. 1, label apparatus 10, comprise 13, two pins 16,17 of 15, one surface-mounted integrated circuits of a base and a double-doublet antenna 11,12.Two pins 16,17 are arranged on surface-mounted integrated circuit 13, and these two pins outwards are connected with magnetically sensitive device 14, and these two pins are in parallel with the equivalent electrical circuit of antenna at chip internal, and a logical circuit of controlling break-make is arranged on the circuit connected.Can control the magnetosensitive module by the break-make of logical circuit and whether be access in chip circuit, thereby can affect the frequency of the antenna be connected with radio-frequency module.When logical circuit disconnects, label antenna is with the first resonant frequency communication.When logical circuit is connected, after being placed on certain lower a period of time of magnetic field intensity, antenna is operated under the second resonant frequency, and its characteristic frequency and signal intensity at least have one and change.
In an example, transmitting terminal 11,12 low electrical resistant material different by one or more made, these materials have higher electric conductivity, copper for example, silver, and aluminium, they and the above-mentioned magnetically sensitive device of mentioning are by two pins 16,17 and antenna 11,12 be connected, when antenna 11,12 be placed on certain lower a period of time of magnetic field intensity after, magnetically sensitive device can cause the variation of one or more transmitting terminal generation resonant frequencies.The frequency of the frequency of this variation and reception and transmission is all different.For example, after magnetically sensitive device is positioned over certain lower a period of time of magnetic field intensity, will causes transmission frequency and accept that in frequency, at least one changes.
In another example, the antenna frequencies value of setting at the beginning will be higher than the antenna frequencies under the certain magnetic field environment, and then, when reaching certain magnetic field, it will reduce.In another example, the antenna frequencies of setting at the beginning is lower than the antenna frequencies under certain magnetic field intensity, and when reaching certain magnetic field intensity, it will rise.Can be used for such magnetically sensitive device of the present invention has: magnetoresistive element and other magneto-resistance type devices etc.
Type difference based on magnetically sensitive device, causing the magnetic field intensity changed may be that a specific magnetic field value may be also a selectively scope of magnetic field value.The length of time must cause the variation of antenna resonance frequency, and antenna quality also can cause different variations.For example, on antenna with the type of magnetically sensitive device can affect the length that changes the antenna resonance frequency required time.
As shown in Figure 2, be the equivalent circuit diagram of RFID label antenna.When the tag coil antenna enters in the alternating magnetic field of read write line generation, the interaction between label antenna and reading and writing device antenna just is similar to transformer.Both coils are equivalent to primary coil and the secondary coil of transformer.The resonant tank formed by label antenna as shown in Figure 2, comprises coil inductance (L), the stray capacitance (C of label antenna
p) and shunt capacitance (C
2), its resonance frequency is
in formula, C is C
pand C
2equivalent capacity in parallel, R
1, R
2equivalent resistance for circuit internal inductance coil and other devices.The carrier frequency that label and read write line two-way communication are used is exactly f.When requiring, the tag antenna coil profile is very little, be that area is little, and need certain operating distance, the aerial coil mutual induction amount that RFID label and read write line are asked just obviously can not practical requirement, can be at the inner Ferrite Material with high permeability that inserts of tag antenna coil, to increase mutual induction amount, thus the little problem of compensating coil xsect.
As shown in Figure 3, for embodiment of the present invention magnetically sensitive device, control the schematic diagram that the logical circuit of break-make is connected with RFID label antenna equivalent electrical circuit.The resonant tank formed by label antenna as shown in the figure, comprises coil inductance (L), the stray capacitance (C of label antenna
p) and shunt capacitance (C
2), its resonance frequency is
formula C is C
pand C
2equivalent capacity in parallel, R
1, R
2equivalent resistance for circuit internal inductance coil and other devices.M is the variable resistor that represents magnetically sensitive device, and S is for controlling the logical circuit of break-make.When logical circuit disconnects, magnetically sensitive device not with the sky line parallel, after now being placed on certain lower a period of time of magnetic field intensity, the first resonant frequency and the signal intensity of antenna remain unchanged.When logical circuit is connected, magnetically sensitive device and a day line parallel, after now being placed on certain lower a period of time of magnetic field intensity, antenna is operated under the second resonant frequency, and its characteristic frequency and signal intensity at least have one and change.
As shown in Figure 4, can detect the sketch of the passive RFID tags device 40 of changes of magnetic field for the embodiment of the present invention.As shown in Figure 4, label apparatus 40 comprises 45, one integrated circuit 43 of a base and a double-doublet antenna 41,42.The magnetically sensitive device 44 be connected with antenna 42 will affect the resistance of antenna 42.The applicable material of magnetically sensitive device 44 can be controlled the frequency that any one had both been fixed a point according to the current voltage of any in antenna 41,42.With regard to an example, fixing up an aerial wire 41,42 can make it in identical frequency, produce resonance.With regard to another example, fixing up an aerial wire 41,42 can make it in different frequency, produce resonance.
In an example, transmitting terminal double- doublet antenna 41,42 low electrical resistant material different by one or more made, and these materials have higher electric conductivity, copper for example, silver, and aluminium, they are connected with the above-mentioned magnetically sensitive device of mentioning, when antenna 41,42 be placed on certain lower a period of time of magnetic field intensity after, magnetically sensitive device can cause the variation of one or more transmitting terminal generation resonant frequencies, thereby causes a different frequency.The frequency of the variation of this frequency and reception and transmission is all different.For example, after magnetically sensitive device is positioned over certain lower a period of time of magnetic field intensity, will causes transmission frequency and accept that in frequency, at least one changes.
In another example, the antenna frequencies value of setting at the beginning will be higher than the antenna frequencies under the certain magnetic field environment, and then, when reaching certain magnetic field, it will reduce.In another example, the antenna frequencies of setting at the beginning is lower than the antenna frequencies under certain magnetic field intensity, and when reaching certain magnetic field intensity, it will rise.The such magnetically sensitive device that can be used for this invention has: magnetoresistive element and other magneto-resistance type devices etc.
Type difference based on magnetically sensitive device, causing the magnetic field intensity changed may be that a specific magnetic field value may be also a selectively scope of magnetic field value.The length of time must cause the variation of antenna resonance frequency, and antenna quality also can cause different variations.For example, on antenna with the type of magnetically sensitive device can affect the length that changes the antenna resonance frequency required time.
As shown in Figure 5, principle of work for magneto sensor, when there is no externally-applied magnetic field, the current density vector of magneto sensor is as shown in the figure shown in (a), in the time of on magnetic field magnetic resistance element surface, due to Hall effect, make certain Hall angle θ of current density vector shift direction of an electric field, as shown in figure (b), the path that so just makes electric current circulate is elongated, and the resistance value between the metal electrode of element two ends has also just increased.When element is rectangle, the distance of electrode is longer, and the growth ratio of resistance is just larger.Hall element basic structure is as shown in figure (c).
As shown in Figure 6, detect by the label apparatus with many antennas a kind of method flow diagram that magnetic field changes for the embodiment of the present invention.Need to consider, the above-mentioned device of mentioning carries out and the exchanging of a plurality of antennas with a label integrated circuit.
As shown in Figure 6,50, RFID reader sends energy and instruction to label apparatus.52, logical circuit is the state in disconnecting at initial time, the antenna reception energy and the instruction that with magnetically sensitive device, are not connected for label apparatus.54, the electromagnetic wave that label apparatus will carry energy is converted into a DC (direct current) voltage, thereby just can make label carry out the requirement of indication.And this conversion need to be used a charge pump, a rectification circuit, or it is interconnected, or to use other energy conversion device.56, label apparatus is by the sky alignment reader transmitted signal be not connected with magnetically sensitive device.58, the energy intensity of receiving signal is measured and recorded to reader.60, reader sends the instruction of connecting logical circuit to label apparatus.62, label apparatus uses the antenna be connected with magnetically sensitive device to send data.64, the energy intensity of signal is received in the reader measurement.66, reader calculated goes out the fiducial value of a reaction signal intensity.68, reader changes into different magnetic field values by fiducial value.With regard to an example, reader can be set the signal that a time period is used for receiving label, if do not receive signal, reader will be recorded as 0 by signal intensity.
In this system, reader will, from the signal strength values of the antenna be not connected with magnetically sensitive device as a reference value, compare it with the signal strength values of the label antenna be connected with magnetically sensitive device.By receive from the signal be connected with magnetically sensitive device with the transmitting terminal be not connected with magnetically sensitive device, reader can be collected the fiducial value that represents unlike signal intensity.Then, the RFID reader can be converted into the residing magnetic field intensity of label to such fiducial value.With regard to a concrete example, the difference that configures this RFID reader and be the RF signal intensity from the antenna that connects or do not connect magnetically sensitive device that the reference data in order to store by use will receive is converted into magnetic field value.
Best situation is, using the antenna that do not connect magnetically sensitive device as a reference, the variation that the coupling due between label and reader can be caused filters out.In addition, just as previously mentioned, magnetically sensitive device is applied in design the variation of the resistance value that can make it and time length that label is placed under specific magnetic fields forms relation one to one.For example, magnetically sensitive device is only positioned on an antenna, can allow like this to change within the specific limits as a kind of function from the signal of RFID label apparatus, and this function just antenna be placed on the function just had after the time under certain magnetic field.The same, the application of the invention, at the RFID label, under passive condition, the RFID reader can detect label apparatus and whether within the acceptable range whether be placed under certain magnetic field and this magnetic field.
With the various RFID labels of two antennas, also can not perceive with magnetically sensitive device the variation in magnetic field, the variation that the variation in perception magnetic field is based on resonant frequency on antenna also can recognize the variation of antenna reception to signal.
For example, by the design of the antenna to being connected with magnetically sensitive device, can make the frequency of antenna at ISM (IndustrialScientific Medical, industry, science, medical science) the interior variation of frequency range, can connect this antenna be connected with magnetically sensitive device and logical circuit on the label of standard.
For example in a concrete example, label antenna can so be set, before in being exposed to the certain magnetic field environment, the resonant frequency of antenna is 902-928MHZ, once but label is exposed in the certain magnetic field environment, impact due to magnetic field, the resonant frequency of antenna is just reduced to 899.5-927.5MHZ, frequency frequency range (902-928MHZ) at U.S. RFID is split into 52 channels, the channel that can not receive of skipping that reader can be random in these 52 channels goes, the benefit of this jump of reader is exactly effectively to prevent that a plurality of readers from attempting the conflict of using same frequency to cause in same physical space.
For example, in an example, RFID frequency range (902-928MHZ) is not to be divided into 52 channels but the antenna settings that on average has been divided into n channel tag is carried out work under this frequency range (902-928MHZ).Because label antenna is connected with magnetically sensitive device, so, as long as magnetic field has surpassed the scope of predefined value, the frequency of operation of antenna tag antenna just drops among (899.5-927.5MHZ) this frequency range.Therefore compare and just channel n is got rid of and goes from band limits with original frequency range, the frequency range (899.5-927.5MHZ) after therefore changing just no longer allows label to carry out exchanging of information with channel n.
In concrete example, if the environment at label place has surpassed the magnetic field range of expection, reader can only send instruction to label by channel 1 to n-1, label also can be made a response, because the antenna in label just can only be worked in this frequency range, when reader sends instruction with the frequency of n channel to label, so no longer reach the 928MHZ label and just no longer make a response because the variation in label magnetic field has caused the resonant frequency of label antenna to drop to 899.5-927.5MHZ, pass information back reader.
Favourable aspect is just by the disappearance of this information interchange, to be reflected due to variation that magnetic field has exceeded the operating frequency of antenna that predefined value causes.
In model, reader can send an instruction between channel n-1 and channel n to label and further check that drift has occurred the operating frequency range of label antenna, because label can receive the instruction sent by channel n-1, and can be to the reader feedback information by channel n-1, because label can not receive the instruction sent by channel n, and can not can, to the reader feedback information, so just determine that drift has occurred the operating frequency range of label antenna by channel n.
The variation in magnetic field causes the frequency of operation of label antenna that drift up and down and current invention occur being not limited in frequency range on average is divided into to n channel.
The embodiment of the present invention can detect changes of magnetic field at lower cost, and the energy that utilizes RFID to obtain, and has solved the powerup issue of magnetic field detection.
The enforcement of each characteristics of this system may relate to software, the combination that hardware also may relate to software and hardware just can reach, and for example the enforcement of many advantages of system is to use a kind of high-caliber processing to realize with the mutual mode exchanged of computer and other equipment machines with OO programming language by programming.Each such function program may be stored in a storage intermediary and for example in ROM (read-only memory), by a computer and processor, be read to realize above-mentioned function.
Those skilled in the art can also recognize the various illustrative components, blocks (illustrativelogical block) that the embodiment of the present invention is listed, unit, and step can pass through electronic hardware, computer software, or both in conjunction with being realized.For the clear replaceability (interchangeability) of showing hardware and software, above-mentioned various illustrative components (illustrativecomponents), unit and step have been described their function generally.Such function is to realize depending on the designing requirement of specific application and whole system by hardware or software.Those skilled in the art can be for every kind of specific application, and can make ins all sorts of ways realizes described function, but this realization should not be understood to exceed the scope of embodiment of the present invention protection.
Various illustrative logical block described in the embodiment of the present invention, or unit can pass through general processor, digital signal processor, special IC (ASIC), field programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or the design of above-mentioned any combination realizes or operates described function.General processor can be microprocessor, and alternatively, this general processor can be also any traditional processor, controller, microcontroller or state machine.Processor also can realize by the combination of calculation element, for example digital signal processor and microprocessor, multi-microprocessor, a Digital Signal Processor Core of one or more microprocessors associating, or any other similarly configuration realize.
Method described in the embodiment of the present invention or the step of algorithm can directly embed hardware, the software module of processor execution or the two combination.Software module can be stored in the storage medium of other arbitrary form in RAM storer, flash memory, ROM storer, eprom memory, eeprom memory, register, hard disk, moveable magnetic disc, CD-ROM or this area.Exemplarily, storage medium can be connected with processor so that processor can be from storage medium reading information, and can deposit write information to storage medium.Alternatively, storage medium can also be integrated in processor.Processor and storage medium can be arranged in ASIC, and ASIC can be arranged in user terminal.Alternatively, processor and storage medium also can be arranged in the different parts in user terminal.
In one or more exemplary designs, the described above-mentioned functions of the embodiment of the present invention can realize in hardware, software, firmware or this three's combination in any.If realize in software, these functions can be stored on the medium with computer-readable, or are transmitted on the medium of computer-readable with one or more instructions or code form.The computer-readable medium comprises the computer storage medium and is convenient to make allows computer program transfer to other local telecommunication media from a place.Storage medium can be the useable medium that any general or special computer can access.For example, such computer readable media can include but not limited to RAM, ROM, EEPROM, CD-ROM or other optical disc storage, disk storage or other magnetic storage device, or other anyly can be read by general or special computer or general or special processor the medium of the program code of form with instruction or data structure and other for carrying or storage.In addition, any connection can suitably be defined as the computer-readable medium, for example,, if software is by a concentric cable, optical fiber computer, twisted-pair feeder, Digital Subscriber Line (DSL) or also being comprised in defined computer-readable medium with wireless way for transmittings such as infrared, wireless and microwave from a web-site, server or other remote resource.Described video disc (disk) and disk (disc) comprise Zip disk, radium-shine dish, CD, DVD, floppy disk and Blu-ray Disc, and disk is usually with the magnetic duplication data, and video disc carries out the optical reproduction data with laser usually.Above-mentioned combination also can be included in the computer-readable medium.
Above-described embodiment; purpose of the present invention, technical scheme and beneficial effect are further described; institute is understood that; the foregoing is only the specific embodiment of the present invention; the protection domain be not intended to limit the present invention; within the spirit and principles in the present invention all, any modification of making, be equal to replacement, improvement etc., within all should being included in protection scope of the present invention.
Claims (14)
1. the label of the RFID with magnetically sensitive device, is characterized in that, two pins are arranged on the chip of described RFID label, two pins of described magnetically sensitive device and this are connected, and form parallel-connection structure with the antenna of described RFID label, the variation of external magnetic field can cause the variation of the resistance of magnetically sensitive device own, a logical circuit of controlling break-make is arranged on the circuit be connected with the chip of RFID label at described magnetically sensitive device, the circuit of this connection is the part of chip with the logical circuit of controlling break-make, the break-make of logical circuit determined magnetically sensitive device whether with the sky line parallel: when logical circuit disconnects, magnetically sensitive device not with the sky line parallel, after now being placed on certain lower a period of time of magnetic field intensity, the first resonant frequency and the signal intensity of antenna remain unchanged, when logical circuit is connected, magnetically sensitive device and a day line parallel, after now being placed on certain lower a period of time of magnetic field intensity, the characteristic frequency of antenna and signal intensity at least have one and change, and now antenna is operated under the second resonant frequency, described RFID label receives the break-make of the instruction of RFID reader transmission with control logic circuit, thereby realizes detecting from the difference between the signal intensity of the different frequency of antenna by comparison the change in magnetic field.
2. as claimed in claim 1 with the RFID label of magnetically sensitive device, it is characterized in that, the antenna of described RFID label is monopole antenna.
3. as claimed in claim 1 with the RFID label of magnetically sensitive device, it is characterized in that, the antenna of described RFID label is double-doublet antenna: described magnetically sensitive device forms parallel-connection structure with antenna wherein; Perhaps described magnetically sensitive device and two antennas form parallel-connection structure simultaneously.
4. as claimed in claim 1 with the RFID label of magnetically sensitive device, it is characterized in that, described magnetically sensitive device is the resistor-type magnetically sensitive device, and described resistor-type magnetically sensitive device comprises: magnetoresistive element and other magneto-resistance type devices.
5. the label of the RFID with magnetically sensitive device, is characterized in that, a pin is arranged on the chip of described RFID label, one end of described magnetically sensitive device is connected with this pin, the other end is connected on the antenna of described RFID label, and form parallel-connection structure with antenna, the variation of external magnetic field can cause the variation of the resistance of magnetically sensitive device own, a logical circuit of controlling break-make is arranged on the circuit be connected with the chip of RFID label at described magnetically sensitive device, the circuit of this connection is the part of chip with the logical circuit of controlling break-make, the break-make of logical circuit determined magnetically sensitive device whether with the sky line parallel: when logical circuit disconnects, magnetically sensitive device not with the sky line parallel, after now being placed on certain lower a period of time of magnetic field intensity, the first resonant frequency and the signal intensity of antenna remain unchanged, when logical circuit is connected, magnetically sensitive device and a day line parallel, after now being placed on certain lower a period of time of magnetic field intensity, the characteristic frequency of antenna and signal intensity at least have one and change, and now antenna is operated under the second resonant frequency, described RFID label receives the break-make of the instruction of RFID reader transmission with control logic circuit, thereby realizes detecting from the difference between the signal intensity of the different frequency of antenna by comparison the change in magnetic field.
6. as claimed in claim 5 with the RFID label of magnetically sensitive device, it is characterized in that, the antenna of described RFID label is monopole antenna.
7. as claimed in claim 5 with the RFID label of magnetically sensitive device, it is characterized in that, the antenna of described RFID label is double-doublet antenna: described magnetically sensitive device forms parallel-connection structure with antenna wherein; Perhaps described magnetically sensitive device and two antennas form parallel-connection structure simultaneously.
8. as claimed in claim 5 with the RFID label of magnetically sensitive device, it is characterized in that, described magnetically sensitive device is the resistor-type magnetically sensitive device, and described resistor-type magnetically sensitive device comprises: magnetoresistive element and other magneto-resistance type devices.
9. the label of the RFID with magnetically sensitive device, it is characterized in that, described magnetically sensitive device is connected on the antenna of described RFID label, and form parallel-connection structure with antenna, the variation of external magnetic field can cause the variation of the resistance of magnetically sensitive device own, a logical circuit of controlling break-make is arranged on the circuit be connected with antenna at described magnetically sensitive device, the circuit of this connection is the part of chip with the logical circuit of controlling break-make, the break-make of logical circuit determined magnetically sensitive device whether with the sky line parallel: when logical circuit disconnects, magnetically sensitive device not with the sky line parallel, after now being placed on certain lower a period of time of magnetic field intensity, the first resonant frequency and the signal intensity of antenna remain unchanged, when logical circuit is connected, magnetically sensitive device and a day line parallel, after now being placed on certain lower a period of time of magnetic field intensity, the characteristic frequency of antenna and signal intensity at least have one and change, and now antenna is operated under the second resonant frequency, described RFID label receives the break-make of the instruction of RFID reader transmission with control logic circuit, thereby realizes detecting from the difference between the signal intensity of the different frequency of antenna by comparison the change in magnetic field.
10. as claimed in claim 9 with the RFID label of magnetically sensitive device, it is characterized in that, the antenna of described RFID label is monopole antenna.
11. with the RFID label of magnetically sensitive device, it is characterized in that as claimed in claim 9, the antenna of described RFID label is double-doublet antenna: described magnetically sensitive device forms parallel-connection structure with antenna wherein; Perhaps described magnetically sensitive device and two antennas form parallel-connection structure simultaneously.
12. with the RFID label of magnetically sensitive device, it is characterized in that as claimed in claim 9, described magnetically sensitive device is the resistor-type magnetically sensitive device, described resistor-type magnetically sensitive device comprises: magnetoresistive element and other magneto-resistance type devices.
13. the rfid system with magnetically sensitive device, described rfid system comprises RFID label and RFID reader, it is characterized in that,
Described RFID label comprises the described label of the RFID with magnetically sensitive device of any one in claim 1-4, or the described label of the RFID with magnetically sensitive device of any one in claim 5-8, or the described label of the RFID with magnetically sensitive device of any one in claim 9-12;
Described RFID reader sends the break-make of instruction with the logical circuit of control RFID label, thereby detects the change in magnetic field from the difference between the signal intensity of the different frequency of antenna by comparison.
14. the method for the magnetic field detection with the rfid system of magnetically sensitive device, is characterized in that, described magnetic field detection method is applied to the described rfid system with magnetically sensitive device of claim 13, comprising:
Send the break-make of instruction with the logical circuit of control RFID label by described RFID reader;
Receive the break-make of the instruction of RFID reader transmission with control logic circuit by the RFID label: when logical circuit disconnects, magnetically sensitive device not with the sky line parallel, after now being placed on certain lower a period of time of magnetic field intensity, the first resonant frequency and the signal intensity of antenna remain unchanged; When logical circuit is connected, magnetically sensitive device and a day line parallel, after now being placed on certain lower a period of time of magnetic field intensity, the characteristic frequency of antenna and signal intensity at least have one and change, and now antenna is operated under the second resonant frequency;
Utilize the comparison of described RFID reader to detect the change in magnetic field from the difference between the signal intensity of the different frequency of antenna.
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| CN2012101836261A CN103455838A (en) | 2012-06-01 | 2012-06-01 | RFID tag with magnetic sensing device, RFID system and magnetic field intensity detection method |
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Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20100079288A1 (en) * | 2008-09-30 | 2010-04-01 | Timothy Collins | RFID Tag Device with Temperature Sensitive Antenna |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| US20100079288A1 (en) * | 2008-09-30 | 2010-04-01 | Timothy Collins | RFID Tag Device with Temperature Sensitive Antenna |
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