CN102819718A - RFID (radio frequency identification device) system for measuring magnetic field intensity and method for measuring magnetic field intensity - Google Patents
RFID (radio frequency identification device) system for measuring magnetic field intensity and method for measuring magnetic field intensity Download PDFInfo
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- CN102819718A CN102819718A CN2012101833649A CN201210183364A CN102819718A CN 102819718 A CN102819718 A CN 102819718A CN 2012101833649 A CN2012101833649 A CN 2012101833649A CN 201210183364 A CN201210183364 A CN 201210183364A CN 102819718 A CN102819718 A CN 102819718A
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Abstract
The invention provides an RFID (radio frequency identification device) system for measuring magnetic field intensity and a method for measuring the magnetic field intensity. The system comprises an RFID reader, a first RFID tag and a second RFID tag; the tags have the same chips and antennas; the first RFID tag works at a first resonant frequency after being arranged at a certain magnetic field intensity for a period of time; the second RFID tag is the RFID tag with a magnetic sensitive device; the magnetic sensitive device and the antenna of the second RFID tag form a parallel structure; a voltage-resistance converter is arranged on a circuit of the magnetic sensitive device connected with the chip of the second RFID tag; the connected circuit and the voltage-resistance converter are a part of the chip; the second RFID tag works at a second resonant frequency after being arranged at the certain magnetic field intensity for a period of time; the first RFID tag and the second RFID tag respectively receive an instruction transmitted by the RFID reader and feed back a signal, and the RFID reader detects the change of the magnetic field by comparing the difference between the signal intensities at different frequencies from the first RFID tag and the second RFID. The change of the magnetic field can be detected at lower cost.
Description
Technical field
The present invention relates to RFID (Radio Frequency Identification, RF identification) technical field, relate in particular to a kind of rfid system of measuring magnetic field intensity and the method for measuring magnetic field intensity thereof.
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 comprises a RFID reader at least, and the radiofrequency signal from one or more RFID labels can launched and accept to this RFID reader in the scope of a setting.This RFID label generally encapsulates; Can be attached on the object, it comprises the chip that an ability and antenna carry out information interchange, and this chip is a microchip; It is an integrated circuit in general; It can be used for storing and process information, the modulation radiofrequency signal, and can move other specific function.The antenna of RFID label is to be used for receiving and sending radiofrequency signal, and is applicable to a kind of special frequency usually.
In some equipment, when the magnetic field intensity that a kind of rfid system of measuring magnetic field intensity has been used to monitor product environment of living in has surpassed the acceptable magnetic field intensity.In general these equipment requirements 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 requirements induction installations also will link to each other 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, its requires when not using lasting energy source or use a kind of adjunct circuit cheaply, can be used for detecting changes of magnetic field.
Summary of the invention
The embodiment of the invention provides a kind of rfid system of measuring magnetic field intensity and the method for measuring magnetic field intensity thereof, detects changes of magnetic field at lower cost.
On the one hand; The embodiment of the invention provides a kind of rfid system of measuring magnetic field intensity; The rfid system of said measuring magnetic field intensity comprises: RFID reader, a RFID label and the 2nd RFID label, and a said RFID label has identical chip and antenna with said the 2nd RFID label; After a said RFID label was placed on certain following a period of time of magnetic field intensity, first resonant frequency and the signal intensity of the antenna of a said RFID label remained unchanged, and this moment, a said RFID label was operated under first resonant frequency; Said the 2nd RFID label has two pins for the RFID label of band magnetically sensitive device on the chip of said the 2nd RFID label; Two pins of said magnetically sensitive device and this link to each other; And form parallel-connection structure with the antenna of said the 2nd RFID label; On magnetically sensitive device and circuit that the chip of the 2nd RFID label is connected, one voltage-resistance conversion equipment is arranged; The circuit of this connection is the part of chip with this voltage-resistance conversion equipment, and the variation of external magnetic field intensity can cause magnetically sensitive device voltage or change in current, after this moment, said the 2nd RFID label was placed on certain following a period of time of magnetic field intensity; The characteristic frequency of the antenna of said the 2nd RFID label and signal intensity have one at least and change, and this moment, said the 2nd RFID label was operated under second resonant frequency; A said RFID label and said the 2nd RFID label receive instruction and the feedback signal that said RFID reader sends respectively, and said RFID reader is through relatively detecting the change in magnetic field from the difference between the signal intensity of a said RFID label and said the 2nd RFID label different frequency.
Optional, in an embodiment of the present invention, the antenna of a said RFID label and said the 2nd RFID label is monopole antenna: the antenna of described magnetically sensitive device and said the 2nd RFID label forms parallel-connection structure.
Optional; In an embodiment of the present invention; The antenna of a said RFID label and said the 2nd RFID label is double-doublet antenna: an antenna of described magnetically sensitive device and said the 2nd RFID label forms parallel-connection structure, perhaps forms parallel-connection structure simultaneously with two antennas.
Optional; In an embodiment of the present invention; Said voltage-resistance conversion equipment comprises: a variable voltage converts the equivalent electrical circuit of variable-resistance device or a ditch type FET or FET to, and said magnetically sensitive device comprises: hall device, Hall switch integrating device, Hall linear Integrated device, magnetodiode, magnetic sensitive transistor, CMOS magnetosensitive device, Wei Gende magnetosensitive device, fluxgate sensor.
On the other hand; The embodiment of the invention provides a kind of rfid system of measuring magnetic field intensity; The rfid system of said measuring magnetic field intensity comprises: RFID reader, a RFID label and the 2nd RFID label, and a said RFID label has identical chip and antenna with said the 2nd RFID label; After a said RFID label was placed on certain following a period of time of magnetic field intensity, first resonant frequency and the signal intensity of the antenna of a said RFID label remained unchanged, and this moment, a said RFID label was operated under first resonant frequency; Said the 2nd RFID label has a pin for the RFID label of band magnetically sensitive device on the chip of said the 2nd RFID label; One end of said magnetically sensitive device links to each other with this pin; The other end is connected on the antenna of said RFID label; And form parallel-connection structure with antenna; On magnetically sensitive device and circuit that the chip of the 2nd RFID label is connected, one voltage-resistance conversion equipment is arranged; The circuit of this connection is the part of chip with this voltage-resistance conversion equipment, and the variation of external magnetic field intensity can cause magnetically sensitive device voltage or change in current, after this moment, said the 2nd RFID label was placed on certain following a period of time of magnetic field intensity; The characteristic frequency of the antenna of said the 2nd RFID label and signal intensity have one at least and change, and this moment, said the 2nd RFID label was operated under second resonant frequency; A said RFID label and said the 2nd RFID label receive instruction and the feedback signal that said RFID reader sends respectively, and said RFID reader is through relatively detecting the change in magnetic field from the difference between the signal intensity of a said RFID label and said the 2nd RFID label different frequency.
Optional, in an embodiment of the present invention, the antenna of a said RFID label and said the 2nd RFID label is monopole antenna: the antenna of described magnetically sensitive device and said the 2nd RFID label forms parallel-connection structure.
Optional; In an embodiment of the present invention; The antenna of a said RFID label and said the 2nd RFID label is double-doublet antenna: an antenna of described magnetically sensitive device and said the 2nd RFID label forms parallel-connection structure, perhaps forms parallel-connection structure simultaneously with two antennas.
Optional; In an embodiment of the present invention; Said voltage-resistance conversion equipment comprises: a variable voltage converts the equivalent electrical circuit of variable-resistance device or a ditch type FET or FET to, and said magnetically sensitive device comprises: hall device, Hall switch integrating device, Hall linear Integrated device, magnetodiode, magnetic sensitive transistor, CMOS magnetosensitive device, Wei Gende magnetosensitive device, fluxgate sensor.
Another aspect; The embodiment of the invention provides a kind of rfid system of measuring magnetic field intensity; The rfid system of said measuring magnetic field intensity comprises: RFID reader, a RFID label and the 2nd RFID label, and a said RFID label has identical chip and antenna with said the 2nd RFID label; After a said RFID label was placed on certain following a period of time of magnetic field intensity, first resonant frequency and the signal intensity of the antenna of a said RFID label remained unchanged, and this moment, a said RFID label was operated under first resonant frequency; Said the 2nd RFID label is the RFID label of band magnetically sensitive device; Said magnetically sensitive device is connected on the antenna of said RFID label; And form parallel-connection structure with antenna; On magnetically sensitive device and circuit that the chip of the 2nd RFID label is connected, one voltage-resistance conversion equipment is arranged; The circuit of this connection is the part of chip with this voltage-resistance conversion equipment, and the variation of external magnetic field intensity can cause magnetically sensitive device voltage or change in current, after this moment, said the 2nd RFID label was placed on certain following a period of time of magnetic field intensity; The characteristic frequency of the antenna of said the 2nd RFID label and signal intensity have one at least and change, and this moment, said the 2nd RFID label was operated under second resonant frequency; A said RFID label and said the 2nd RFID label receive instruction and the feedback signal that said RFID reader sends respectively, and said RFID reader is through relatively detecting the change in magnetic field from the difference between the signal intensity of a said RFID label and said the 2nd RFID label different frequency.
Optional, in an embodiment of the present invention, the antenna of a said RFID label and said the 2nd RFID label is monopole antenna: the antenna of described magnetically sensitive device and said the 2nd RFID label forms parallel-connection structure.
Optional; In an embodiment of the present invention; The antenna of a said RFID label and said the 2nd RFID label is double-doublet antenna: an antenna of described magnetically sensitive device and said the 2nd RFID label forms parallel-connection structure, perhaps forms parallel-connection structure simultaneously with two antennas.
Optional; In an embodiment of the present invention; Said voltage-resistance conversion equipment comprises: a variable voltage converts the equivalent electrical circuit of variable-resistance device or a ditch type FET or FET to, and said magnetically sensitive device comprises: hall device, Hall switch integrating device, Hall linear Integrated device, magnetodiode, magnetic sensitive transistor, CMOS magnetosensitive device, Wei Gende magnetosensitive device, fluxgate sensor.
Again on the one hand; The embodiment of the invention provides a kind of method of rfid system measuring magnetic field intensity of measuring magnetic field intensity; Said method is applied to the rfid system of above-mentioned measuring magnetic field intensity; Comprise: after a said RFID label is placed on certain following a period of time of magnetic field intensity; First resonant frequency and the signal intensity of the antenna of a said RFID label remain unchanged; This moment, a said RFID label was operated under first resonant frequency: after said the 2nd RFID label was placed on certain following a period of time of magnetic field intensity, the characteristic frequency of the antenna of said the 2nd RFID label and signal intensity had one at least and change, and this moment, said the 2nd RFID label was operated under second resonant frequency; Send instruction through said RFID reader and give a said RFID label and said the 2nd RFID label and receiving feedback signals; Difference when utilizing the work of more said RFID label of said RFID reader and said the 2nd RFID label between the signal intensity of different frequency detects the change in magnetic field.
Technique scheme has following beneficial effect: because adopt the rfid system of said measuring magnetic field intensity to comprise: RFID reader, a RFID label and the 2nd RFID label, and a said RFID label has identical chip and antenna with said the 2nd RFID label; After a said RFID label was placed on certain following a period of time of magnetic field intensity, a said RFID label was operated under first resonant frequency; Said the 2nd RFID label is the RFID label of band magnetically sensitive device; The antenna of said magnetically sensitive device and said the 2nd RFID label forms parallel-connection structure; On magnetically sensitive device and circuit that the chip of the 2nd RFID label is connected, one voltage-resistance conversion equipment is arranged; The circuit of this connection is the part of chip with this voltage-resistance conversion equipment, and after this moment, said the 2nd RFID label was placed on certain following a period of time of magnetic field intensity, said the 2nd RFID label was operated under second resonant frequency; A said RFID label and said the 2nd RFID label receive instruction and the feedback signal that said RFID reader sends respectively; Said RFID reader is through relatively detecting the technological means of the change in magnetic field from the difference between the signal intensity of a said RFID label and said the 2nd RFID label different frequency; So reached the technique effect that detects changes of magnetic field at lower cost; And the energy that utilizes RFID to obtain, solved the powerup issue that magnetic field intensity detects.
Description of drawings
In order to be illustrated more clearly in the embodiment of the invention or technical scheme of the prior art; To do to introduce simply to the accompanying drawing of required use in embodiment or the description of the Prior Art below; Obviously, the accompanying drawing in describing below only is some embodiments of the present invention, for those of ordinary skills; Under the prerequisite of not paying creative work, can also obtain other accompanying drawing according to these accompanying drawings.
Fig. 1 is the rfid system structural representation of a kind of measuring magnetic field intensity of the embodiment of the invention;
The synoptic diagram that Fig. 2 is connected with the 2nd RFID label chip for embodiment of the invention magnetically sensitive device;
Fig. 3 is the equivalent circuit diagram of the embodiment of the invention the 2nd RFID label chip inside antenna;
Fig. 4 is the synoptic diagram that embodiment of the invention magnetically sensitive device, voltage-resistance conversion equipment are connected with the 2nd RFID label chip inside antenna equivalent electrical circuit;
The synoptic diagram that Fig. 5 directly is connected for embodiment of the invention magnetically sensitive device and RFID label antenna;
Fig. 6 is the structure key diagram of embodiment of the invention magnetically sensitive device;
Fig. 7 is the method flow diagram of the embodiment of the invention based on the measuring magnetic field intensity of signal intensity.
Embodiment
To combine the accompanying drawing in the embodiment of the invention below, the technical scheme in the embodiment of the invention is carried out clear, intactly description, obviously, described embodiment only is the present invention's part embodiment, rather than whole embodiment.Based on the embodiment among the present invention, those of ordinary skills are not making the every other embodiment that is obtained under the creative work prerequisite, all belong to the scope of the present invention's protection.
As shown in Figure 1; Rfid system structural representation for a kind of measuring magnetic field intensity of the embodiment of the invention; The rfid system of said measuring magnetic field intensity comprises: RFID reader 1, a RFID label 2 and the 2nd RFID label 3, and a said RFID label 2 has identical chip and antenna with said the 2nd RFID label 3; After a said RFID label 2 was placed on certain following a period of time of magnetic field intensity, first resonant frequency and the signal intensity of the antenna of a said RFID label 2 remained unchanged, and this moment, a said RFID label 2 was operated under first resonant frequency; Said the 2nd RFID label 3 is the RFID label of band magnetically sensitive device; The antenna of said magnetically sensitive device and said the 2nd RFID label 3 forms parallel-connection structure; On magnetically sensitive device and circuit that the chip of the 2nd RFID label is connected, one voltage-resistance conversion equipment is arranged; The circuit of this connection is the part of chip with this voltage-resistance conversion equipment; The variation of external magnetic field intensity can cause magnetically sensitive device voltage or change in current; After this moment, said the 2nd RFID label was placed on certain following a period of time of magnetic field intensity, the characteristic frequency of the antenna of said the 2nd RFID label 3 and signal intensity had one at least and change, and this moment, said the 2nd RFID label 3 was operated under second resonant frequency; A said RFID label 2 receives instruction and the feedback signal that said RFID reader 1 sends respectively with said the 2nd RFID label 3, and said RFID reader 1 is through relatively detecting the change in magnetic field from the difference between the signal intensity of a said RFID label 2 and said the 2nd RFID label 3 different frequencies.The magnetically sensitive device of the embodiment of the invention links to each other with the chip of the 2nd RFID label and has three kinds of situation at least:
The two pins structure:
The embodiment of the invention is a kind of rfid system that is used for detecting changes of magnetic field.This system has comprised two RFID labels: a RFID label and the 2nd RFID label.Two pins are arranged on the chip of the 2nd RFID label; Two pins of magnetically sensitive device and this link to each other; Form parallel-connection structure with antenna; On magnetically sensitive device and circuit that the chip of the 2nd RFID label is connected, one voltage-resistance conversion equipment is arranged, the circuit of this connection is the part of chip with this voltage-resistance conversion equipment, and the variation of external magnetic field intensity can cause magnetically sensitive device voltage or change in current.After this moment, said the 2nd RFID label was placed on certain following a period of time of magnetic field intensity, first resonant frequency and the signal intensity of the antenna of a RFID label remained unchanged.The characteristic frequency of the antenna of the 2nd RFID label and signal intensity have one at least and change, and this moment, antenna was operated under second resonant frequency.The RFID reader can send instruction to label, realizes communication, and the difference in the time of can be through a RFID label and the 2nd RFID label work relatively between the signal intensity of different frequency detects the change in magnetic field.
With regard to an instance, this system has comprised a kind of RFID label, and said label comprises a RFID label and the 2nd RFID label, and a RFID label and the 2nd RFID label all have only an antenna.Two pins are arranged on the chip of the 2nd RFID label, and two pins of magnetically sensitive device and this link to each other, and form parallel-connection structure with antenna.On magnetically sensitive device and circuit that the chip of the 2nd RFID label is connected, one voltage-resistance conversion equipment is arranged; The circuit of this connection is the part of chip with this voltage-resistance conversion equipment; The variation of external magnetic field intensity can cause magnetically sensitive device voltage or change in current; After this moment, said the 2nd RFID label was placed on certain following a period of time of magnetic field intensity, first resonant frequency and the signal intensity of the antenna of a RFID label remained unchanged.The characteristic frequency of the antenna of the 2nd RFID label and signal intensity have one at least and change, and this moment, antenna was operated under second resonant frequency.The RFID reader can send instruction to label, realizes communication, and the difference in the time of can be through a RFID label and the 2nd RFID label work relatively between the signal intensity of different frequency detects the change in magnetic field.
Or rather; Said voltage-resistance conversion equipment comprises: a variable voltage converts the equivalent electrical circuit of variable-resistance device or a ditch type FET or FET etc. to, and said magnetically sensitive device comprises: hall device, Hall switch integrating device, Hall linear Integrated device, magnetodiode, magnetic sensitive transistor, CMOS magnetosensitive device, Wei Gende magnetosensitive device, fluxgate sensor etc.
With regard to another instance, this system has comprised two RFID labels: a RFID label and the 2nd RFID label; The one RFID label and the 2nd RFID label all have two antennas.Two pins are arranged on the chip of the 2nd RFID label; Two pins of magnetically sensitive device and this link to each other; Form parallel-connection structure simultaneously with two antennas; On magnetically sensitive device and circuit that the chip of the 2nd RFID label is connected, one voltage-resistance conversion equipment is arranged, the circuit of this connection is the part of chip with this voltage-resistance conversion equipment.The variation of external magnetic field intensity can cause magnetically sensitive device voltage or change in current.The situation that this and the 2nd RFID label only contain an antenna is similar.After being placed on certain following a period of time of magnetic field intensity, first resonant frequency and the signal intensity of the antenna of a RFID label remain unchanged this moment.The characteristic frequency of the antenna of the 2nd RFID label and signal intensity have one at least and change, and this moment, said the 2nd RFID label antenna was operated under second resonant frequency.The RFID reader can send instruction to label, realizes communication, and the difference in the time of can be through a RFID label and the 2nd RFID label work relatively between the signal intensity of different frequency detects the change in magnetic field.Or rather; Said voltage-resistance conversion equipment comprises: a variable voltage converts the equivalent electrical circuit of variable-resistance device or a ditch type FET or FET etc. to, and said magnetically sensitive device comprises: hall device, Hall switch integrating device, Hall linear Integrated device, magnetodiode, magnetic sensitive transistor, CMOS magnetosensitive device, Wei Gende magnetosensitive device, fluxgate sensor etc.
One pin configuration:
This system has comprised two RFID labels: a RFID label and the 2nd RFID label, a pin is arranged on the chip of the 2nd RFID label, and this pin outwards links to each other with an end of magnetically sensitive device, and the other end of magnetically sensitive device is directly linked on the 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 day line parallel.On magnetically sensitive device and circuit that the chip of the 2nd RFID label is connected, one voltage-resistance conversion equipment is arranged; The circuit of this connection is the part of chip with this voltage-resistance conversion equipment, and the variation of external magnetic field intensity can cause magnetically sensitive device voltage or change in current.After being placed on certain following a period of time of magnetic field intensity, first resonant frequency and the signal intensity of the antenna of a RFID label remain unchanged this moment.The characteristic frequency of the antenna of the 2nd RFID label and signal intensity have one at least and change, and this moment, said the 2nd RFID label antenna was operated under second resonant frequency.The RFID reader can send instruction to label, realizes communication, and the difference in the time of can be through a RFID label and the 2nd RFID label work relatively between the signal intensity of different frequency detects the change in magnetic field.
With regard to an instance, this system has comprised two RFID labels: a RFID label and the 2nd RFID label; The one RFID label and the 2nd RFID label all have only an antenna.A pin is arranged on the chip of the 2nd RFID label; Magnetically sensitive device links to each other with this pin; The magnetically sensitive device other end is directly linked on the antenna; Form parallel-connection structure with antenna, on magnetically sensitive device and circuit that the chip of the 2nd RFID label is connected, one voltage-resistance conversion equipment is arranged, the circuit of this connection and this voltage-resistance conversion equipment are the parts of chip.The variation of external magnetic field intensity can cause magnetically sensitive device voltage or change in current.After being placed on certain following a period of time of magnetic field intensity, first resonant frequency and the signal intensity of the antenna of a RFID label remain unchanged this moment.The characteristic frequency of the antenna of the 2nd RFID label and signal intensity have one at least and change, and this moment, said the 2nd RFID label antenna was operated under second resonant frequency.The RFID reader can send instruction to label, realizes communication, and the difference in the time of can be through a RFID label and the 2nd RFID label work relatively between the signal intensity of different frequency detects the change in magnetic field.Or rather; Said voltage-resistance conversion equipment comprises: a variable voltage converts the equivalent electrical circuit of variable-resistance device or a ditch type FET or FET etc. to, and said magnetically sensitive device comprises: hall device, Hall switch integrating device, Hall linear Integrated device, magnetodiode, magnetic sensitive transistor, CMOS magnetosensitive device, Wei Gende magnetosensitive device, fluxgate sensor etc.
No pin configuration:
This system has comprised two RFID labels: a RFID label and the 2nd RFID label, there is not pin on the chip of the 2nd RFID label, and magnetically sensitive device is directly linked on the antenna.In this case, the antenna that links to each other with magnetically sensitive device can not break away from magnetically sensitive device and with normal frequency for communication.After being placed on certain following a period of time of magnetic field intensity, the characteristic frequency of antenna and signal intensity have one at least and change.The RFID reader can send instruction to label apparatus, realizes communication, through relatively detect the change in magnetic field from the difference between the signal intensity of the different frequency of a RFID label and the 2nd RFID label.
With regard to an instance, this system has comprised two RFID labels: a RFID label and the 2nd RFID label; The one RFID label and the 2nd RFID label all have only an antenna.There is not pin on the chip of the 2nd RFID label; Magnetically sensitive device is directly linked on the antenna; On magnetically sensitive device and circuit that the chip of the 2nd RFID label is connected, one voltage-resistance conversion equipment is arranged, the circuit of this connection is the part of chip with this voltage-resistance conversion equipment.The variation of external magnetic field intensity can cause magnetically sensitive device voltage or change in current.After being placed on certain following a period of time of magnetic field intensity, first resonant frequency and the signal intensity of the antenna of a RFID label remain unchanged this moment.The characteristic frequency of the antenna of the 2nd RFID label and signal intensity have one at least and change, and this moment, said the 2nd RFID label antenna was operated under second resonant frequency.The RFID reader can send instruction to label, and the difference between the signal intensity of the different frequency during through relatively a RFID label and second label work can detect the change in magnetic field.Or rather; Said voltage-resistance conversion equipment comprises: a variable voltage converts the equivalent electrical circuit of variable-resistance device or a ditch type FET or FET etc. to, and said magnetically sensitive device comprises: hall device, Hall switch integrating device, Hall linear Integrated device, magnetodiode, magnetic sensitive transistor, CMOS magnetosensitive device, Wei Gende magnetosensitive device, fluxgate sensor 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 following a period of time of magnetic field intensity, the characteristic frequency of the antenna that links to each other 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 through comparison.
With regard to a kind of instantiation of magnetically sensitive device, the method for simultaneous comparison numerical value comprises that these are compared numerical value compares with most signal strength values.These signal strength values belong to different frequencies, and interrelate with the field strength values of majority, can detect the level of magnetic field intensity simultaneously based on the above-mentioned comparison of mentioning.
Yet with regard to another aspect, a rfid system comprises two RFID label apparatus and a RFID reader device.These two RFID label apparatus are used to send two kinds of signals; Promptly; The signal of the signal of the one RFID label and the 2nd RFID label; Reader is received the signal of a RFID label and the signal of the 2nd RFID label respectively, through the fiducial value between the signal strength values of RFID label of background process and the 2nd RFID label, and is converted into these fiducial values the varying level of magnetic field intensity.
Again on the one hand; The embodiment of the invention provides a kind of method of rfid system measuring magnetic field intensity of measuring magnetic field intensity; Said method is applied to the rfid system of above-mentioned measuring magnetic field intensity; Comprise: after a said RFID label is placed on certain following a period of time of magnetic field intensity; First resonant frequency and the signal intensity of the antenna of a said RFID label remain unchanged; This moment, a said RFID label was operated under first resonant frequency: after said the 2nd RFID label was placed on certain following a period of time of magnetic field intensity, the characteristic frequency of the antenna of said the 2nd RFID label and signal intensity had one at least and change, and this moment, said the 2nd RFID label was operated under second resonant frequency; Send instruction through said RFID reader and give a said RFID label and said the 2nd RFID label and receiving feedback signals; Difference when utilizing the work of more said RFID label of said RFID reader and said the 2nd RFID label between the signal intensity of different frequency detects the change in magnetic field.
As shown in Figure 2, the synoptic diagram of the magnetosensitive label 10 that is connected with the 2nd RFID label chip for embodiment of the invention magnetically sensitive device.Among Fig. 2, label apparatus 10 comprises 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 the surface-mounted integrated circuit 13, and these two pins outwards link to each other with magnetically sensitive device 14, and these two pins are parallelly connected with the equivalent electrical circuit of antenna at chip internal.This label can communicate with reader.
In an example, transmitting terminal 11,12 is processed by one or more different low electrical resistant materials, and these materials have higher electric conductivity; Copper for example, silver, and aluminium, they with the above-mentioned magnetically sensitive device of mentioning through two pins 16; 17 is continuous with antenna 11,12, when antenna 11; 12 be placed on certain following 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 following a period of time of magnetic field intensity, will causes sending frequency and accept that at least one changes in the frequency.
In another example, the antenna frequencies value of setting at the beginning will be higher than the antenna frequencies under the certain magnetic field intensity environment, and when reaching certain magnetic field intensity, it will reduce then.In another example, the antenna frequencies of setting at the beginning is lower than the antenna frequencies under the certain magnetic field intensity, and it will rise when reaching certain magnetic field intensity.Can be used for such magnetically sensitive device of the present invention has: hall device, Hall switch integrating device, Hall linear Integrated device, magnetodiode, magnetic sensitive transistor, CMOS magnetosensitive device, Wei Gende magnetosensitive device, the responsive transposition of fluxgate etc.
Type based on magnetically sensitive device is different, and the magnetic field intensity that causes changing possibly be that a specific field strength values also possibly be a scope of field strength values selectively.The length of time must cause the variation of antenna resonance frequency, and antenna quality also can cause different variations.The type of the magnetically sensitive device that for example, has on the antenna can influence the length that changes the antenna resonance frequency required time.
As shown in Figure 3, be the equivalent circuit diagram of a RFID label antenna.In the alternating magnetic field that tag coil antenna entering read write line produces, the interaction between label antenna and the reading and writing device antenna just is similar to transformer.Both coils are equivalent to the primary coil and the secondary coil of transformer.Resonant tank by label antenna forms is 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 does
C is C in the formula
pAnd C
2Parallelly connected equivalent capacity, 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.The tag antenna coil profile is very little when requiring; 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 have the Ferrite Material of high permeability in the inner insertion of tag antenna coil; With the increase mutual induction amount, thus the little problem of compensating coil xsect.
As shown in Figure 4, be embodiment of the invention magnetically sensitive device, voltage-resistance conversion equipment and the synoptic diagram that is connected with the 2nd RFID label antenna equivalent electrical circuit.Resonant tank by label antenna forms is 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 does
Formula C is C
pAnd C
2Parallelly connected equivalent capacity, R
1, R
2Equivalent resistance for circuit internal inductance coil and other devices.R
3Be the equivalent resistance of connecting with magnetically sensitive device, F is voltage-resistance conversion equipment.M is the variable resistor of representative magnetically sensitive device.After this label was placed on certain following a period of time of magnetic field intensity, its characteristic frequency and signal intensity had one at least and change, and antenna is operated under second resonant frequency.
As shown in Figure 5, can detect the sketch of the passive RFID tags device 40 of changes of magnetic field for the embodiment of the 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 that links to each other with antenna 42 will influence the resistance of antenna 42.The material that magnetically sensitive device 44 is suitable for can be controlled the frequency that any one had both been fixed a point according to any one current voltage in the antenna 41,42.With regard to an instance, fixing up an aerial wire 41,42 can make it produce resonance in identical frequency.With regard to another instance, fixing up an aerial wire 41,42 can make it produce resonance in different frequency.
In an example, transmitting terminal double-doublet antenna 41,42 is processed by one or more different low electrical resistant materials; These materials have higher electric conductivity, copper for example, silver; And aluminium, they link to each other with the above-mentioned magnetically sensitive device of mentioning, when antenna 41; 42 be placed on certain following 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 following a period of time of magnetic field intensity, will causes sending frequency and accept that at least one changes in the frequency.
In another example, the antenna frequencies value of setting at the beginning will be higher than the antenna frequencies under the certain magnetic field intensity environment, and when reaching certain magnetic field intensity, it will reduce then.In another example, the antenna frequencies of setting at the beginning is lower than the antenna frequencies under the certain magnetic field intensity, and it will rise when reaching certain magnetic field intensity.The such magnetically sensitive device that can be used for this invention comprises: hall device, Hall switch integrating device, Hall linear Integrated device, magnetodiode, magnetic sensitive transistor, CMOS magnetosensitive device, Wei Gende magnetosensitive device, fluxgate sensor etc.
Type based on magnetically sensitive device is different, and the magnetic field intensity that causes changing possibly be that a specific field strength values also possibly be a scope of field strength values selectively.The length of time must cause the variation of antenna resonance frequency, and antenna quality also can cause different variations.The type of the magnetically sensitive device that for example, has on the antenna can influence the length that changes the antenna resonance frequency required time.
As shown in Figure 6, the Wei Gende magnetic-sensitive elements be according to the Wei Gende effect process magnetic-sensitive elements.Ferromagnetism metal alloys such as permalloy can make the coercive force of an ectonexine marked difference occur through after the special processing: outer field coercive force is than the big one magnitude of internal layer.This tinsel is Wei Gendesi, like figure (1).Because ectonexine coercive force difference is bigger, Wei Gendesi has two kinds of stable magnetized states: ectonexine is by equidirectional magnetization: ectonexine is by magnetic reversal.Utilize suitable external magnetic field effect, the magnetized state of Wei Gendesi internal layer is reversed suddenly, change state b suddenly into from state a, or change a suddenly into from state b, the effect of generation state counter-rotating is called the Wei Gende effect under this outside magnetic field effect.Like figure (2), be the touch sensor of processing with Wei Gendesi.The last detecting coil of being full of of Wei Gendesi, its below is one makes Wei Gendesi permanent magnet magnetized.When top key moves to downwards when contacting with lower part, top magnet is more near Wei Gendesi, but pole polarity and following magnet are opposite, and this just makes DOM counter-rotating of silk internal layer, spike pulse of detecting coil output.Wei Gendesi generally is about several centimetres, and the about 0.3mm of diameter, magneto sensor coil turn are about 1000～2000 circles, and voltage pulse output is a few voltage magnitudes, and pulse width is 20 μ s.
As shown in Figure 7, be the method flow diagram of the embodiment of the invention based on the measuring magnetic field intensity of signal intensity, said method is applied to the rfid system of above-mentioned measuring magnetic field intensity, comprising:
701, a said RFID label is placed on certain following a period of time of magnetic field intensity after, first resonant frequency and the signal intensity of the antenna of a said RFID label remain unchanged, this moment a said RFID label be operated under first resonant frequency:
702, said the 2nd RFID label is placed on certain following a period of time of magnetic field intensity after; The characteristic frequency of the antenna of said the 2nd RFID label and signal intensity have one at least and change, and this moment, said the 2nd RFID label was operated under second resonant frequency;
703, send instruction through said RFID reader and give a said RFID label and said the 2nd RFID label and receiving feedback signals;
Difference when 704, utilizing the work of more said RFID label of said RFID reader and said the 2nd RFID label between the signal intensity of different frequency detects the change in magnetic field.
The RFID reader can be measured the energy intensity of receiving signal, calculates the fiducial value of a reaction signal intensity, then fiducial value is changed into different field strength values.With regard to an instance, 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 with signal intensity.
In this system, the RFID reader will compare its signal strength values with the 2nd RFID label that links to each other with magnetically sensitive device from the signal strength values of a RFID label that does not link to each other with magnetically sensitive device as a reference value.Through receive from linking to each other with magnetically sensitive device and a RFID label that does not link to each other and the signal of the 2nd RFID label with magnetically sensitive device, the RFID reader can be collected the fiducial value of representing 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 instance, disposing this RFID reader is to be converted into field strength values for the difference from the RF signal intensity that connects the RFID label that does not perhaps connect magnetically sensitive device that will receive through the reference data of using storage.
Best situation is, with a RFID label that does not connect magnetically sensitive device as a reference, can be with owing to the variation that coupling caused between label and the reader filters out.In addition, as before mention, magnetically sensitive device is applied to the time length that variation and the 2nd RFID label of the resistance value that can make it in the design be placed under the particular magnetic field strength and forms one-to-one correspondence.The same, the application of the invention, under the passive condition of RFID label, the RFID reader can detect label apparatus whether be placed under certain magnetic field intensity and this magnetic field intensity whether within the acceptable range.
Do not use the various RFID labels of two antennas also can perceive the variation of magnetic field intensity with magnetically sensitive device, the variation that the variation of perception magnetic field intensity is based on resonant frequency on the antenna also can recognize the variation that antenna receives signal.
For example pass through design to the antenna that links to each other with magnetically sensitive device; The frequency that can make antenna is at ISM (Industrial Scientific Medical; Industry, science, medical science) the interior variation of frequency range, can connect this antenna that links to each other with magnetically sensitive device and logical circuit on the label of standard.
For example label antenna can so be set in a concrete instance; Before in being exposed to certain magnetic field intensity environment; The resonant frequency of antenna is 902-928MHZ, but in a single day label is exposed in the certain magnetic field intensity environment, because the influence of magnetic field intensity; 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, and reader can be skipped the channel that can not receive at random in these 52 channels, and the benefit of this jump of reader is exactly to prevent effectively 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 links to each other with magnetically sensitive device, so as long as magnetic field intensity 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 just channel n to be got rid of from band limits with original frequency range and go, the frequency range (899.5-927.5MHZ) after therefore changing is carried out exchanging of information with regard to no longer allowing label with channel n.
In concrete instance; If the environment at label place has surpassed the magnetic field intensity scope of expection; Reader can only send instruction to label through channel 1 to n-1; Label also can be made a response because the antenna in the label just can only work in this frequency range, when reader with the frequency of n channel when label sends instruction; So no longer reach the 928MHZ label and just no longer make a response because the variation of label magnetic field intensity has caused the resonant frequency of label antenna to drop to 899.5-927.5MHZ, pass information back reader.
Favourable aspect is just to be reflected by the disappearance of this information interchange owing to variation that magnetic field intensity 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 taken place the operating frequency range of label antenna; Because label can receive the instruction that sends through channel n-1; And can be to the reader feedback information through channel n-1; Because label can not receive the instruction that sends through channel n, and can not can so just confirm that drift has taken place the operating frequency range of label antenna to the reader feedback information through channel n.
The variation of magnetic field intensity causes the frequency of operation of label antenna to take place upwards to be not limited in downward drift and present invention frequency range on average is divided into n channel.
The embodiment of the invention can detect changes of magnetic field at lower cost, and the energy that utilizes RFID to obtain, and has solved the powerup issue that magnetic field intensity detects.
The enforcement of each characteristics of this system may relate to software; The combination that hardware also possibly relate to software and hardware just can reach, and for example the enforcement of many advantages of system is to realize with the mutual mode that exchanges of computer and other equipment machines with object oriented programming languages with a kind of high-caliber processing through programming.Each such function program for example possibly be stored in the storage intermediary in the ROM (read-only memory) to be read by a computer and processor and realize above-mentioned function.
Those skilled in the art can also recognize the various illustrative components, blocks (illustrative logical block) that the embodiment of the invention is listed, and unit and step can be passed through electronic hardware, computer software, or both combinations realize.Be the clear replaceability (interchangeability) of showing hardware and software, above-mentioned various illustrative components (illustrative components), unit and step have been described their function generally.Such function is to realize depending on the designing requirement of certain applications and total system through hardware or software.Those skilled in the art can be for every kind of certain applications, and can make ins all sorts of ways realizes described function, but this realization should not be understood that to exceed the scope of embodiment of the invention protection.
Various illustrative logical block described in the embodiment of the invention; Or the 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 also can be any traditional processor, controller, microcontroller or state machine.Processor also can realize through the combination of calculation element, for example digital signal processor and microprocessor, a plurality of microprocessors, Digital Signal Processor Core of one or more microprocessors associatings, or any other similarly configuration realize.
The method described in the embodiment of the 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 read information from storage medium, and can deposit write information to storage medium.Alternatively, storage medium can also be integrated in the processor.Processor and storage medium can be arranged among the ASIC, and ASIC can be arranged in the user terminal.Alternatively, processor and storage medium also can be arranged in the various parts in the user terminal.
In one or more exemplary designs, the described above-mentioned functions of the embodiment of the invention can realize in hardware, software, firmware or this three's combination in any.If in software, realize, these functions can be stored on the media with computer-readable, or are transmitted on the media of computer-readable with one or more instructions or code form.The computer-readable media comprises that the computer storage medium lets computer program transfer to other local telecommunication media from a place with being convenient to make.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 any can be used to carry or store with instruction or data structure and other can be read the media of the program code of form by general or special computer or general or special processor.In addition; Any connection can suitably be defined as the computer-readable media; For example, if software is through a concentric cable, optical fiber computer, twisted-pair feeder, Digital Subscriber Line (DSL) or also being comprised in the defined computer-readable media with wireless mode transmission such as for example infrared, wireless and microwaves 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 media.
Above-described embodiment; The object of the invention, technical scheme and beneficial effect have been carried out further explain, and institute it should be understood that the above is merely embodiment of the present invention; And be not used in qualification protection scope of the present invention; All within spirit of the present invention and principle, any modification of being made, be equal to replacement, improvement etc., all should be included within protection scope of the present invention.
Claims (13)
1. the rfid system of a measuring magnetic field intensity; It is characterized in that; The rfid system of said measuring magnetic field intensity comprises: RFID reader, a RFID label and the 2nd RFID label, and a said RFID label has identical chip and antenna with said the 2nd RFID label; After a said RFID label was placed on certain following a period of time of magnetic field intensity, first resonant frequency and the signal intensity of the antenna of a said RFID label remained unchanged, and this moment, a said RFID label was operated under first resonant frequency; Said the 2nd RFID label has two pins for the RFID label of band magnetically sensitive device on the chip of said the 2nd RFID label; Two pins of said magnetically sensitive device and this link to each other; And form parallel-connection structure with the antenna of said the 2nd RFID label; On magnetically sensitive device and circuit that the chip of the 2nd RFID label is connected, have-voltage-resistance conversion equipment; The circuit of this connection is the part of chip with this voltage-resistance conversion equipment, and the variation of external magnetic field intensity can cause magnetically sensitive device voltage or change in current, after this moment, said the 2nd RFID label was placed on certain following a period of time of magnetic field intensity; The characteristic frequency of the antenna of said the 2nd RFID label and signal intensity have one at least and change, and this moment, said the 2nd RFID label was operated under second resonant frequency; A said RFID label and said the 2nd RFID label receive instruction and the feedback signal that said RFID reader sends respectively, and said RFID reader is through relatively detecting the change in magnetic field from the difference between the signal intensity of a said RFID label and said the 2nd RFID label different frequency.
2. the rfid system of measuring magnetic field intensity according to claim 1, it is characterized in that the antenna of a said RFID label and said the 2nd RFID label is monopole antenna: the antenna of described magnetically sensitive device and said the 2nd RFID label forms parallel-connection structure.
3. the rfid system of measuring magnetic field intensity according to claim 1; It is characterized in that; The antenna of a said RFID label and said the 2nd RFID label is double-doublet antenna: an antenna of described magnetically sensitive device and said the 2nd RFID label forms parallel-connection structure, perhaps forms parallel-connection structure simultaneously with two antennas.
4. the rfid system of measuring magnetic field intensity according to claim 1; It is characterized in that; Said voltage-resistance conversion equipment comprises: a variable voltage converts the equivalent electrical circuit of variable-resistance device or a ditch type FET or FET to, and said magnetically sensitive device comprises: hall device, Hall switch integrating device, Hall linear Integrated device, magnetodiode, magnetic sensitive transistor, CMOS magnetosensitive device, Wei Gende magnetosensitive device, fluxgate sensor.
5. the rfid system of a measuring magnetic field intensity; It is characterized in that; The rfid system of said measuring magnetic field intensity comprises: RFID reader, a RFID label and the 2nd RFID label, and a said RFID label has identical chip and antenna with said the 2nd RFID label; After a said RFID label was placed on certain following a period of time of magnetic field intensity, first resonant frequency and the signal intensity of the antenna of a said RFID label remained unchanged, and this moment, a said RFID label was operated under first resonant frequency; Said the 2nd RFID label has a pin for the RFID label of band magnetically sensitive device on the chip of said the 2nd RFID label; One end of said magnetically sensitive device links to each other with this pin; The other end is connected on the antenna of said RFID label; And form parallel-connection structure with antenna; On magnetically sensitive device and circuit that the chip of the 2nd RFID label is connected, one voltage-resistance conversion equipment is arranged; The circuit of this connection is the part of chip with this voltage-resistance conversion equipment, and the variation of external magnetic field intensity can cause magnetically sensitive device voltage or change in current, after this moment, said the 2nd RFID label was placed on certain following a period of time of magnetic field intensity; The characteristic frequency of the antenna of said the 2nd RFID label and signal intensity have one at least and change, and this moment, said the 2nd RFID label was operated under second resonant frequency; A said RFID label and said the 2nd RFID label receive instruction and the feedback signal that said RFID reader sends respectively, and said RFID reader is through relatively detecting the change in magnetic field from the difference between the signal intensity of a said RFID label and said the 2nd RFID label different frequency.
6. like the rfid system of the said measuring magnetic field intensity of claim 5, it is characterized in that the antenna of a said RFID label and said the 2nd RFID label is monopole antenna: the antenna of described magnetically sensitive device and said the 2nd RFID label forms parallel-connection structure.
7. like the rfid system of the said measuring magnetic field intensity of claim 5; It is characterized in that; The antenna of a said RFID label and said the 2nd RFID label is double-doublet antenna: an antenna of described magnetically sensitive device and said the 2nd RFID label forms parallel-connection structure, perhaps forms parallel-connection structure simultaneously with two antennas.
8. like the rfid system of the said measuring magnetic field intensity of claim 5; It is characterized in that; Said voltage-resistance conversion equipment comprises: a variable voltage converts the equivalent electrical circuit of variable-resistance device or a ditch type FET or FET to, and said magnetically sensitive device comprises: hall device, Hall switch integrating device, Hall linear Integrated device, magnetodiode, magnetic sensitive transistor, CMOS magnetosensitive device, Wei Gende magnetosensitive device, fluxgate sensor.
9. the rfid system of a measuring magnetic field intensity; It is characterized in that; The rfid system of said measuring magnetic field intensity comprises: RFID reader, a RFID label and the 2nd RFID label, and a said RFID label has identical chip and antenna with said the 2nd RFID label; After a said RFID label was placed on certain following a period of time of magnetic field intensity, first resonant frequency and the signal intensity of the antenna of a said RFID label remained unchanged, and this moment, a said RFID label was operated under first resonant frequency; Said the 2nd RFID label is the RFID label of band magnetically sensitive device; Said magnetically sensitive device is connected on the antenna of signing on said RFID border; And form parallel-connection structure with antenna; On magnetically sensitive device and circuit that the chip of the 2nd RFID label is connected, one voltage-resistance conversion equipment is arranged; The circuit of this connection is the part of chip with this voltage-resistance conversion equipment, and the variation of external magnetic field intensity can cause magnetically sensitive device voltage or change in current, after this moment, said the 2nd RFID label was placed on certain following a period of time of magnetic field intensity; The characteristic frequency of the antenna of said the 2nd RFID label and signal intensity have one at least and change, and this moment, said the 2nd RFID label was operated under second resonant frequency; A said RFID label and said the 2nd RFID label receive instruction and the feedback signal that said RFID reader sends respectively, and said RFID reader is through relatively detecting the change in magnetic field from the difference between the signal intensity of a said RFID label and said the 2nd RFID label different frequency.
10. like the rfid system of the said measuring magnetic field intensity of claim 9, it is characterized in that the antenna of a said RFID label and said the 2nd RFID label is monopole antenna: the antenna of described magnetically sensitive device and said the 2nd RFID label forms parallel-connection structure.
11. rfid system like the said measuring magnetic field intensity of claim 9; It is characterized in that; The antenna of a said RFID label and said the 2nd RFID label is double-doublet antenna: an antenna of described magnetically sensitive device and said the 2nd RFID label forms parallel-connection structure, perhaps forms parallel-connection structure simultaneously with two antennas.
12. rfid system like the said measuring magnetic field intensity of claim 9; It is characterized in that; Said voltage-resistance conversion equipment comprises: a variable voltage converts the equivalent electrical circuit of variable-resistance device or a ditch type FET or FET to, and said magnetically sensitive device comprises: hall device, Hall switch integrating device, Hall linear Integrated device, magnetodiode, magnetic sensitive transistor, CMOS magnetosensitive device, Wei Gende magnetosensitive device, fluxgate sensor.
13. the method for the rfid system measuring magnetic field intensity of a measuring magnetic field intensity; It is characterized in that; Said method is applied to the rfid system of each said measuring magnetic field intensity among the claim 1-4; Or the rfid system of each said measuring magnetic field intensity among the claim 5-8, or the rfid system of each said measuring magnetic field intensity among the claim 9-12, comprising:
After a said RFID label was placed on certain following a period of time of magnetic field intensity, first resonant frequency and the signal intensity of the antenna of a said RFID label remained unchanged, and this moment, a said RFID label was operated under first resonant frequency:
After said the 2nd RFID label was placed on certain following a period of time of magnetic field intensity, the characteristic frequency of the antenna of said the 2nd RFID label and signal intensity had one at least and change, and this moment, said the 2nd RFID label was operated under second resonant frequency;
Send instruction through said RFID reader and give a said RFID label and said the 2nd RFID label and receiving feedback signals;
Difference when utilizing the work of more said RFID label of said RFID reader and said the 2nd RFID label between the signal intensity of different frequency detects the change in magnetic field.
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| CN109313828A (en) * | 2016-06-30 | 2019-02-05 | 利塔尔两合公司 | Blocking device, particularly door lock assembly and corresponding method for switchgear |
| CN110398626A (en) * | 2019-07-11 | 2019-11-01 | 珠海格力电器股份有限公司 | A kind of communication signal detection circuit and method |
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