CN102750570B - A kind of RFID label tag, rfid system and stressed detection method with force sensitive device - Google Patents
A kind of RFID label tag, rfid system and stressed detection method with force sensitive device Download PDFInfo
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- CN102750570B CN102750570B CN201210179499.8A CN201210179499A CN102750570B CN 102750570 B CN102750570 B CN 102750570B CN 201210179499 A CN201210179499 A CN 201210179499A CN 102750570 B CN102750570 B CN 102750570B
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Abstract
The invention provides a kind of RFID label tag with force sensitive device, rfid system and stressed detection method, the antenna of force sensitive device and RFID label tag forms parallel-connection structure, the circuit that force sensitive device is connected with the chip of RFID label tag has logical circuit and an electric piezo-resistive conversion equipment controlling break-make, the circuit of this connection, this logical circuit and this electric piezo-resistive conversion equipment are parts for chip: when logical circuit disconnects, force sensitive device not with sky line parallel, if sensor is under pressure, first resonant frequency of antenna and signal intensity remain unchanged, when logical circuit is connected, force sensitive device and sky line parallel, if sensor is under pressure, now Antenna Operation is under the second resonant frequency, RFID label tag receives instruction that RFID reader sends with the break-make of control logic circuit, thus realizes the change being detected pressure by the difference between comparing from the signal intensity of the different frequency of antenna.It can detect the change of pressure at lower cost.
Description
Technical field
The present invention relates to RFID(RadioFrequencyIdentification, radio-frequency (RF) identification) technical field, particularly relate to a kind of RFID label tag, rfid system and stressed detection method with force sensitive device.
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 this RFID reader can transmit and receive the radiofrequency signal from one or more RFID label tag in the scope of a setting.This RFID label tag is generally encapsulated, and can paste on one 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, modulation /demodulation radiofrequency signal, and the specific function can running other.The antenna of RFID label tag is used to receive and send radiofrequency signal, and is usually applicable to a kind of special frequency.
In some equipment, the rfid system with force sensitive device has been used to monitor the stressed acceptable that when exceeded of environment residing for product by force intensity.In general these equipment requirement induction installations will have a lasting energy source, be used for detecting the change of pressure, but this can increase the cost of equipment.In addition, some equipment requirement induction installations also will be connected with a comparator circuit, thus detect the degree size departing from reference voltage, and this requirement considerably increases the cost of equipment.In a word, improve rfid system and be necessary, it requires the change that can be used for when not using lasting energy source or use a kind of adjunct circuit of low cost detecting pressure.
Summary of the invention
The embodiment of the present invention provides a kind of RFID label tag, rfid system and stressed detection method with force sensitive device, detects the change of pressure at lower cost.
On the one hand, embodiments provide a kind of RFID label tag with force sensitive device, the chip of described RFID label tag has two pins, described force sensitive device and this two pins are connected, and form parallel-connection structure with the antenna of described RFID label tag, the extraneous change by force intensity can cause the change of force sensitive device both end voltage or electric current, the circuit that described force sensitive device is connected with the chip of RFID label tag has logical circuit and an electric piezo-resistive conversion equipment controlling break-make, the circuit of this connection, this logical circuit and this electric piezo-resistive conversion equipment are parts for chip, electricity piezo-resistive conversion equipment is for converting the change of resistance to by the change of force sensitive device both end voltage or electric current, the break-make of logical circuit determine force sensitive device whether with sky line parallel: when logical circuit disconnects, force sensitive device not with sky line parallel, if now sensor is under pressure, first resonant frequency of antenna and signal intensity remain unchanged, when logical circuit is connected, force sensitive device and sky line parallel, if now sensor is under pressure, the characteristic frequency of antenna and signal intensity at least have one and change, and now Antenna Operation is under the second resonant frequency, described RFID label tag receives instruction that RFID reader sends with the break-make of control logic circuit, thus realizes the change being detected pressure by the difference between comparing from the signal intensity of the different frequency of antenna.
Optionally, in an embodiment of the present invention, the antenna of described RFID label tag is monopole antenna.
Optionally, in an embodiment of the present invention, the antenna of described RFID label tag is double-doublet antenna: described force sensitive device and the electric piezo-resistive conversion equipment that is connected with this force sensitive device and a wherein antenna form parallel-connection structure; Or described force sensitive device and the electric piezo-resistive conversion equipment be connected with this force sensitive device and two antennas form parallel-connection structure simultaneously.
Optionally, in an embodiment of the present invention, described electric piezo-resistive conversion equipment comprises: a variable voltage converts variable-resistance device to, or a ditch type field effect transistor, or the equivalent electrical circuit of field effect transistor, described force sensitive device comprises: pressure drag type pressure sensor, piezoelectric pressure sensor, piezoelectric type device for measuring force, piezoelectric type acceleration pick-up unit, macromolecular material piezoelectric sensing device, resonance sensor, type vibration wire pressure sensitive device, vibration cylinder type pressure sensitive device, diaphragm-vibrating type pressure sensitive device, inductance type pressure sensitive device, air gap inductance formula pressure sensitive device, inductance type oil pressure sensor, torque detecting apparatus.
On the other hand, embodiments provide a kind of RFID label tag with force sensitive device, the chip of described RFID label tag has a pin, one end of described force sensitive device is connected with this pin, the other end is connected on the antenna of described RFID label tag, and form parallel-connection structure with antenna, the extraneous change by force intensity can cause the change of force sensitive device both end voltage or electric current, the circuit that described force sensitive device is connected with the chip of RFID label tag has logical circuit and an electric piezo-resistive conversion equipment controlling break-make, the circuit of this connection, this logical circuit and this electric piezo-resistive conversion equipment are parts for chip, electricity piezo-resistive conversion equipment is for converting the change of resistance to by the change of force sensitive device both end voltage or electric current, the break-make of logical circuit determine force sensitive device whether with sky line parallel: when logical circuit disconnects, force sensitive device not with sky line parallel, if now sensor is under pressure, first resonant frequency of antenna and signal intensity remain unchanged, when logical circuit is connected, force sensitive device and sky line parallel, if now sensor is under pressure, the characteristic frequency of antenna and signal intensity at least have one and change, and now Antenna Operation is under the second resonant frequency, described RFID label tag receives instruction that RFID reader sends with the break-make of control logic circuit, thus realizes the change being detected pressure by the difference between comparing from the signal intensity of the different frequency of antenna.
Optionally, in an embodiment of the present invention, the antenna of described RFID label tag is monopole antenna.
Optionally, in an embodiment of the present invention, the antenna of described RFID label tag is double-doublet antenna: described force sensitive device and the electric piezo-resistive conversion equipment that is connected with this force sensitive device and a wherein antenna form parallel-connection structure; Or described force sensitive device and the electric piezo-resistive conversion equipment be connected with this force sensitive device and two antennas form parallel-connection structure simultaneously.
Optionally, in an embodiment of the present invention, described electric piezo-resistive conversion equipment comprises: a variable voltage converts variable-resistance device to, or a ditch type field effect transistor, or the equivalent electrical circuit of field effect transistor, described force sensitive device comprises: pressure drag type pressure sensor, piezoelectric pressure sensor, piezoelectric type device for measuring force, piezoelectric type acceleration pick-up unit, macromolecular material piezoelectric sensing device, resonance sensor, type vibration wire pressure sensitive device, vibration cylinder type pressure sensitive device, diaphragm-vibrating type pressure sensitive device, inductance type pressure sensitive device, air gap inductance formula pressure sensitive device, inductance type oil pressure sensor, torque detecting apparatus.
Another aspect, embodiments provide a kind of RFID label tag with force sensitive device, described force sensitive device is connected on the antenna of described RFID label tag, and form parallel-connection structure with antenna, the extraneous change by force intensity can cause the change of force sensitive device both end voltage or electric current, the circuit that described force sensitive device is connected with antenna has logical circuit and an electric piezo-resistive conversion equipment controlling break-make, the circuit of this connection, this logical circuit and this electric piezo-resistive conversion equipment are parts for chip, electricity piezo-resistive conversion equipment is for converting the change of resistance to by the change of force sensitive device both end voltage or electric current, the break-make of logical circuit determine force sensitive device whether with sky line parallel: when logical circuit disconnects, force sensitive device not with sky line parallel, if now sensor is under pressure, first resonant frequency of antenna and signal intensity remain unchanged, when logical circuit is connected, force sensitive device and sky line parallel, if now sensor is under pressure, the characteristic frequency of antenna and signal intensity at least have one and change, and now Antenna Operation is under the second resonant frequency, described RFID label tag receives instruction that RFID reader sends with the break-make of control logic circuit, thus realizes the change being detected pressure by the difference between comparing from the signal intensity of the different frequency of antenna.
Optionally, in an embodiment of the present invention, the antenna of described RFID label tag is monopole antenna.
Optionally, in an embodiment of the present invention, the antenna of described RFID label tag is double-doublet antenna: described force sensitive device and the electric piezo-resistive conversion equipment that is connected with this force sensitive device and a wherein antenna form parallel-connection structure; Or described force sensitive device and the electric piezo-resistive conversion equipment be connected with this force sensitive device and two antennas form parallel-connection structure simultaneously.
Optionally, in an embodiment of the present invention, described electric piezo-resistive conversion equipment comprises: a variable voltage converts variable-resistance device to, or a ditch type field effect transistor, or the equivalent electrical circuit of field effect transistor, described force sensitive device comprises: pressure drag type pressure sensor, piezoelectric pressure sensor, piezoelectric type device for measuring force, piezoelectric type acceleration pick-up unit, macromolecular material piezoelectric sensing device, resonance sensor, type vibration wire pressure sensitive device, vibration cylinder type pressure sensitive device, diaphragm-vibrating type pressure sensitive device, inductance type pressure sensitive device, air gap inductance formula pressure sensitive device, inductance type oil pressure sensor, torque detecting apparatus.
Another aspect, embodiments provide a kind of rfid system with force sensitive device, described rfid system comprises RFID label tag and RFID reader, and described RFID label tag comprises the RFID label tag of above-mentioned band force sensitive device; Described RFID reader sends instruction to control the break-make of the logical circuit of RFID label tag, thus detects the change of pressure by the difference between comparing from the signal intensity of the different frequency of antenna.
Again on the one hand, embodiments provide a kind of stressed detection method of the rfid system with force sensitive device, described stressed detection method is applied to the rfid system of above-mentioned band force sensitive device, comprising: send instruction to control the break-make of the logical circuit of RFID label tag by described RFID reader; The instruction of RFID reader transmission is received with the break-make of control logic circuit: when logical circuit disconnects by RFID label tag, force sensitive device not with sky line parallel, if now sensor is under pressure, the first resonant frequency of antenna and signal intensity remain unchanged; When logical circuit is connected, force sensitive device and sky line parallel, if now sensor is under pressure, the characteristic frequency of antenna and signal intensity at least have one and change, and now Antenna Operation is under the second resonant frequency; Utilize described RFID reader to compare from the signal intensity of the different frequency of antenna between difference to detect the change of pressure.
Technique scheme has following beneficial effect: because adopt the antenna of force sensitive device and RFID label tag to form parallel-connection structure, the circuit that force sensitive device is connected with the chip of RFID label tag has logical circuit and an electric piezo-resistive conversion equipment controlling break-make, the circuit of this connection, this logical circuit and this electric piezo-resistive conversion equipment are parts for chip: when logical circuit disconnects, force sensitive device not with sky line parallel, if sensor is under pressure, the first resonant frequency of antenna and signal intensity remain unchanged; When logical circuit is connected, force sensitive device and sky line parallel, if sensor is under pressure, now Antenna Operation is under the second resonant frequency; RFID label tag receives the instruction of RFID reader transmission with the break-make of control logic circuit, thus realize the technological means being detected the change of pressure by the difference between comparing from the signal intensity of the different frequency of antenna, so reach the technique effect that can detect the change of pressure at lower cost, and the energy utilizing RFID to obtain, solve the powerup issue of stressed detection.
Accompanying drawing explanation
In order to be illustrated more clearly in the embodiment of the present invention or technical scheme of the prior art, be briefly described to the accompanying drawing used required in embodiment or description of the prior art below, apparently, accompanying drawing in the following describes is only some embodiments of the present invention, for those of ordinary skill in the art, under the prerequisite not paying creative work, other accompanying drawing can also be obtained according to these accompanying drawings.
Fig. 1 is the schematic diagram that embodiment of the present invention force sensitive device is connected with RFID label chip;
Fig. 2 is the equivalent circuit diagram of RFID label chip inside antenna;
The schematic diagram that Fig. 3 is embodiment of the present invention force sensitive device, logic switch and electric piezo-resistive conversion equipment are connected with RFID label chip inside antenna equivalent electrical circuit;
Fig. 4 is the schematic diagram that embodiment of the present invention force sensitive device is directly connected with RFID label antenna;
Fig. 5 is the structure key diagram of embodiment of the present invention force sensitive device;
Fig. 6 is the process flow diagram of the embodiment of the present invention based on the stressed strength detecting method of signal intensity.
Embodiment
Below in conjunction with the accompanying drawing in the embodiment of the present invention, be clearly and completely described the technical scheme in the embodiment of the present invention, obviously, described embodiment is only the present invention's part embodiment, instead of whole embodiments.Based on the embodiment in the present invention, those of ordinary skill in the art, not making the every other embodiment obtained under creative work prerequisite, belong to the scope of protection of the invention.
The force sensitive device of the embodiment of the present invention is connected with the chip of RFID label tag and at least there are three kinds of situations:
Two pins structure:
The present invention is a kind of device, system and technology of being used for detecting stressed Strength Changes.This system contains a label, the chip of this label has two pins.Force sensitive device and this two pins are connected, and form parallel-connection structure with antenna.The extraneous change by force intensity can cause the change of force sensitive device both end voltage or electric current.The circuit that pin is connected with chip has logical circuit and an electric piezo-resistive conversion equipment controlling break-make, and the circuit of this connection, the logical circuit controlling break-make and electric piezo-resistive conversion equipment are parts for chip.The effect of electricity piezo-resistive conversion equipment is the change change of force sensitive device both end voltage or electric current being converted to resistance.
The break-make of logical circuit determine force sensitive device whether with sky line parallel.When logical circuit disconnects, force sensitive device not with sky line parallel.If now force sensitive device sensor is under pressure, the first resonant frequency of antenna and signal intensity remain unchanged.When logical circuit is connected, force sensitive device and sky line parallel, if now sensor is under pressure, the characteristic frequency of antenna and signal intensity at least have one and change, and now Antenna Operation is under the second resonant frequency.Reader can send the break-make of instruction control logic circuit to label, when logical circuit is connected, can be detected the change of pressure by the difference between comparing from the signal intensity of the different frequency of antenna.
With regard to an example, this system contains a label, this label only has an antenna (monopole antenna).The chip of this label there are two pins.Force sensitive device and this two pins are connected, and form parallel-connection structure with antenna.The circuit that pin is connected with chip has logical circuit and an electric piezo-resistive conversion equipment controlling break-make, and the circuit of this connection, the logical circuit controlling break-make and electric piezo-resistive conversion equipment are parts for chip.The effect of electricity piezo-resistive conversion equipment is the change change of force sensitive device both end voltage or electric current being converted to resistance.
If force sensitive device sensor is under pressure when logical circuit is connected, antenna features frequency and signal intensity at least have one and change, under it is operated in the second resonant frequency.Reader can send instruction to label, and can detect the change of pressure by the difference between the signal intensity of different frequency during Compare Logic connecting and disconnecting of the circuit.Or rather, electric piezo-resistive conversion equipment can be equivalent electrical circuit variable voltage being converted to variable-resistance device, a ditch type field effect transistor or field effect transistor.And the instantiation of force sensitive device comprises: pressure drag type pressure sensor, piezoelectric pressure sensor, piezoelectric type device for measuring force, piezoelectric type acceleration pick-up unit, macromolecular material piezoelectric sensing device, resonance sensor, type vibration wire pressure sensitive device, vibration cylinder type pressure sensitive device, diaphragm-vibrating type pressure sensitive device, inductance type pressure sensitive device, air gap inductance formula pressure sensitive device, inductance type oil pressure sensor, torque detecting apparatus etc.
With regard to another example, this system contains a label, this label has two antennas (double-doublet antenna).Force sensitive device and this two pins are connected, and form parallel-connection structure with first antenna.The circuit that pin is connected with chip has logical circuit and an electric piezo-resistive conversion equipment controlling break-make, and the circuit of this connection, the logical circuit controlling break-make and electric piezo-resistive conversion equipment are parts for chip.The effect of electricity piezo-resistive conversion equipment is the change change of force sensitive device both end voltage or electric current being converted to resistance.The electric piezo-resistive conversion equipment be now connected with force sensitive device also with first sky line parallel, and second antenna is all the time with the first resonant frequency proper communication.
When logical circuit is connected, be placed on certain under force intensity, first antenna features frequency and signal intensity have at least a meeting to change, under it is operated in the second resonant frequency.Reader can send instruction to label, and can detect the change of pressure by the difference between the signal intensity of the different frequency of first and second antennas during Compare Logic circuit ON.Also the change of pressure can be detected by the difference between the signal intensity of the different frequency during logical circuit break-make that compares second antenna self.Or rather, electric piezo-resistive conversion equipment can be equivalent electrical circuit variable voltage being converted to variable-resistance device, a ditch type field effect transistor or field effect transistor.And the instantiation of force sensitive device comprises: pressure drag type pressure sensor, piezoelectric pressure sensor, piezoelectric type device for measuring force, piezoelectric type acceleration pick-up unit, macromolecular material piezoelectric sensing device, resonance sensor, type vibration wire pressure sensitive device, vibration cylinder type pressure sensitive device, diaphragm-vibrating type pressure sensitive device, inductance type pressure sensitive device, air gap inductance formula pressure sensitive device, inductance type oil pressure sensor, torque detecting apparatus etc.
One pin configuration:
The chip of this label only can have a pin, and this pin is outwards connected with one end of force sensitive device, and the other end of force sensitive device is directly linked on antenna.Pin the tie point of chip internal and the situation of two pins similar, finally remain the object that will reach with sky line parallel.The circuit be simultaneously connected with chip internal circuits at pin there is a logical circuit controlling break-make.In addition, an electric piezo-resistive conversion equipment in parallel again on the circuit of antenna, electric piezo-resistive conversion equipment has again circuit to be connected with the two-termial line of force sensitive device and logical circuit.
When logical circuit disconnects, force sensitive device not with sky line parallel, if now sensor is under pressure, the first resonant frequency of antenna and signal intensity remain unchanged.When logical circuit is connected, force sensitive device and sky line parallel, if now sensor is under pressure, antenna features frequency and signal intensity at least have one and change, under it is operated in the second resonant frequency.Reader can send the break-make of instruction control logic circuit to label, when logical circuit is connected, can be detected the change of pressure by the difference between comparing from the signal intensity of the different frequency of antenna.
With regard to an example, this system contains a label, this label only has an antenna (monopole antenna).Force sensitive device is connected with this pin, and the other end of force sensitive device is directly linked on antenna, forms parallel-connection structure with this root antenna.The circuit that pin is connected with chip has logical circuit and an electric piezo-resistive conversion equipment controlling break-make, and the circuit of this connection, the logical circuit controlling break-make and electric piezo-resistive conversion equipment are parts for chip.The effect of electricity piezo-resistive conversion equipment is the change change of force sensitive device both end voltage or electric current being converted to resistance.
If sensor is under pressure when logical circuit is connected, antenna features frequency and signal intensity at least have one and change, under it is operated in the second resonant frequency.Reader can send instruction to label, and can detect the change of pressure by the difference between the signal intensity of different frequency during Compare Logic connecting and disconnecting of the circuit.Or rather, electric piezo-resistive conversion equipment can be equivalent electrical circuit variable voltage being converted to variable-resistance device, a ditch type field effect transistor or field effect transistor.And the instantiation of force sensitive device comprises: pressure drag type pressure sensor, piezoelectric pressure sensor, piezoelectric type device for measuring force, piezoelectric type acceleration pick-up unit, macromolecular material piezoelectric sensing device, resonance sensor, type vibration wire pressure sensitive device, vibration cylinder type pressure sensitive device, diaphragm-vibrating type pressure sensitive device, inductance type pressure sensitive device, air gap inductance formula pressure sensitive device, inductance type oil pressure sensor, torque detecting apparatus etc.
With regard to another example, this system contains a label, this label has two antennas (double-doublet antenna).Force sensitive device with this one by one pin be connected, the other end of force sensitive device is directly linked on antenna, forms parallel-connection structure with first antenna.The circuit that pin is connected with chip has logical circuit and an electric piezo-resistive conversion equipment controlling break-make, and the circuit of this connection, the logical circuit controlling break-make and electric piezo-resistive conversion equipment are parts for chip.The effect of electricity piezo-resistive conversion equipment is the change change of force sensitive device both end voltage or electric current being converted to resistance.The electric piezo-resistive conversion equipment be now connected with force sensitive device also with first sky line parallel, and second antenna is all the time with the first resonant frequency proper communication.
When logical circuit is connected, be placed on certain under force intensity, first Antenna Operation is under the second resonant frequency, and its characteristic frequency and signal intensity have at least a meeting to change.Reader can send instruction to label, and during by Compare Logic circuit ON, the difference between the signal intensity of the different frequency of first and second antennas can detect the change of pressure.Also the change of pressure can be detected by the difference between the signal intensity of the different frequency during logical circuit break-make that compares first antenna self.Or rather, electric piezo-resistive conversion equipment can be equivalent electrical circuit variable voltage being converted to variable-resistance device, a ditch type field effect transistor or field effect transistor.And the instantiation of force sensitive device comprises: pressure drag type pressure sensor, piezoelectric pressure sensor, piezoelectric type device for measuring force, piezoelectric type acceleration pick-up unit, macromolecular material piezoelectric sensing device, resonance sensor, type vibration wire pressure sensitive device, vibration cylinder type pressure sensitive device, diaphragm-vibrating type pressure sensitive device, inductance type pressure sensitive device, air gap inductance formula pressure sensitive device, inductance type oil pressure sensor, torque detecting apparatus etc.
Without pin configuration:
When not having pin on the chip of RFID label tag, force sensitive device can directly be linked on antenna.Force sensitive device and antenna form parallel-connection structure.The circuit that antenna is connected with chip has logical circuit and an electric piezo-resistive conversion equipment controlling break-make, and the circuit of this connection, the logical circuit controlling break-make and electric piezo-resistive conversion equipment are parts for chip.The effect of electricity piezo-resistive conversion equipment is the change change of force sensitive device both end voltage or electric current being converted to resistance.In this case, the antenna be connected with force sensitive device can not depart from force sensitive device and communicate with the first resonant frequency.If sensor is under pressure, the second resonant frequency of antenna and signal intensity at least have one and change.Reader can send instruction to label apparatus, is detected the change of pressure by the difference between comparing from the signal intensity of the different frequency of antenna.
With regard to an example, this system contains a label, this label has two antennas (double-doublet antenna).Force sensitive device is directly connected with first antenna.Force sensitive device and antenna form parallel-connection structure.The circuit that antenna is connected with chip has logical circuit and an electric piezo-resistive conversion equipment controlling break-make, and the circuit of this connection, the logical circuit controlling break-make and electric piezo-resistive conversion equipment are parts for chip.The effect of electricity piezo-resistive conversion equipment is the change change of force sensitive device both end voltage or electric current being converted to resistance.And second antenna is not connected with force sensitive device all the time with the first resonant frequency proper communication.When being placed on, certain by under force intensity, first antenna features frequency and signal intensity have at least a meeting to change, under it is operated in the second resonant frequency, and the characteristic frequency of second antenna and signal intensity constant.Reader can send instruction to label, and can detect the change of pressure by the difference between the signal intensity of the different frequency that compares first and second antennas.Or rather, electric piezo-resistive conversion equipment can be equivalent electrical circuit variable voltage being converted to variable-resistance device, a ditch type field effect transistor or field effect transistor.And the instantiation of force sensitive device comprises: pressure drag type pressure sensor, piezoelectric pressure sensor, piezoelectric type device for measuring force, piezoelectric type acceleration pick-up unit, macromolecular material piezoelectric sensing device, resonance sensor, type vibration wire pressure sensitive device, vibration cylinder type pressure sensitive device, diaphragm-vibrating type pressure sensitive device, inductance type pressure sensitive device, air gap inductance formula pressure sensitive device, inductance type oil pressure sensor, torque detecting apparatus etc.
In the same way, the chip of antenna can be with and also can not be with pin, one can be with also can be with multiple pin.The radical of antenna can be one, two or even many.Also can connect one or more force sensitive device accordingly, the model of force sensitive device can be the same or different simultaneously.In addition, the electric piezo-resistive conversion equipment be attached thereto also can have many changes.With regard to a kind of instantiation of device, when being placed on certain by under force intensity, the resonant frequency of the antenna be connected with force sensitive device and signal intensity have at least a meeting to change.Reader can send instruction to label apparatus, is detected the change of pressure by the difference between comparing from the signal intensity of the different frequency of antenna.
With regard to a kind of instantiation of force sensitive device, the method that simultaneous compares numerical value comprises and these are compared numerical value compares with most signal strength values.These signal strength values belong to different frequencies, and with being associated by force intensity of majority, simultaneously based on above-mentioned mention relatively can detect stressed intensity.
But with regard to another aspect, a rfid system comprises a RFID label tag device and a RFID reader device.This RFID label tag device is used to transmission two kinds of signals, and signal when signal when namely above-mentioned logical circuit disconnects and logical circuit are connected, these two kinds of signals have at least a kind of meeting to respond to the request be subject to.RFID reader device is used at least sending a request to RFID label tag device.Fiducial value between signal strength values when signal strength values when installation reading device is the logical circuit connection in order to receive from label and logical circuit disconnect, and these fiducial values are converted into stressed varying level.
In an example, the antenna of RFID label tag is connected with force sensitive device, and this connection line has a logical circuit controlling break-make.Force sensitive device and antenna form parallel-connection structure.The circuit that antenna is connected with chip has logical circuit and an electric piezo-resistive conversion equipment controlling break-make, and the circuit of this connection, the logical circuit controlling break-make and electric piezo-resistive conversion equipment are parts for chip.The effect of electricity piezo-resistive conversion equipment is the change change of force sensitive device both end voltage or electric current being converted to resistance.In logical circuit break-make whether two kinds of situations, this antenna has corresponding with it two kinds of different frequencies, i.e. the first resonant frequency and the second resonant frequency.Connect when logical circuit and this label apparatus be positioned over certain under force intensity, due to the change of resonant frequency, the intensity level of unlike signal will be produced.
In an example, RFID label tag device comprises first, second two antennas.Better, first antenna is connected with electric piezo-resistive conversion equipment with force sensitive device, when this label apparatus is placed on certain under force intensity, due to the change of resonant frequency, the different of secondary signal intensity level and the first signal strength values will be produced.
Another aspect, embodiments provide a kind of rfid system with force sensitive device, described rfid system comprises RFID label tag and RFID reader, and described RFID label tag comprises the RFID label tag of above-mentioned band force sensitive device; Described RFID reader sends instruction to control the break-make of the logical circuit of RFID label tag, thus detects the change of pressure by the difference between comparing from the signal intensity of the different frequency of antenna.
Again on the one hand, embodiments provide a kind of stressed detection method of the rfid system with force sensitive device, described stressed detection method is applied to the rfid system of above-mentioned band force sensitive device, comprising: send instruction to control the break-make of the logical circuit of RFID label tag by described RFID reader; The instruction of RFID reader transmission is received with the break-make of control logic circuit: when logical circuit disconnects by RFID label tag, force sensitive device not with sky line parallel, if now sensor is under pressure, the first resonant frequency of antenna and signal intensity remain unchanged; When logical circuit is connected, force sensitive device and sky line parallel, if now sensor is under pressure, the characteristic frequency of antenna and signal intensity at least have one and change, and now Antenna Operation is under the second resonant frequency; Utilize described RFID reader to compare from the signal intensity of the different frequency of antenna between difference to detect the change of pressure.
As shown in Figure 1, the schematic diagram of the force sensitive label 10 be connected with RFID label chip for embodiment of the present invention force sensitive device.As shown in Figure 1, label apparatus 10, comprises a base 15, surface-mounted integrated circuit 13, two pins 16,17 and one double-doublet antennas 11,12.Surface-mounted integrated circuit 13 has two pins 16,17, these two pins are outwards connected with force sensitive device 14, and these two pins are in parallel with the equivalent electrical circuit of antenna at chip internal, and on the circuit connected, have a logical circuit controlling break-make.Force sensitive device and antenna form parallel-connection structure.The circuit that antenna is connected with chip has logical circuit and an electric piezo-resistive conversion equipment controlling break-make, and the circuit of this connection, the logical circuit controlling break-make and electric piezo-resistive conversion equipment are parts for chip.The effect of electricity piezo-resistive conversion equipment is the change change of force sensitive device both end voltage or electric current being converted to resistance.Force sensitive device can be controlled by the break-make of logical circuit whether to be access in chip circuit, thus the frequency of the antenna be connected with radio-frequency module can be affected.When logical circuit disconnects, label antenna is with the first resonant frequency communication.When logical circuit is connected, be placed on certain under force intensity, Antenna Operation is under the second resonant frequency, and its characteristic frequency and signal intensity at least have one and change.
In an example, transmitting terminal antenna 11,12 is made up of one or more different low electrical resistant materials, these materials have higher electric conductivity, such as copper, silver, and aluminium, they and the above-mentioned force sensitive device mentioned are by two pins 16,17 and antenna 11,12 be connected, when antenna 11,12 are placed on certain under force intensity, and force sensitive device can cause the change of one or more transmitting terminal generation resonant frequency.The frequency of this frequency changed and reception and transmission is all different.Such as, when logical circuit is connected, force sensitive device is positioned over certain under force intensity, will cause in transmission frequency and receive frequency that at least one changes.
In another example, the antenna frequencies value set at the beginning by higher than the antenna frequencies under certain force environment, then when reach certain stressed time, it will reduce.In another example, the antenna frequencies set at the beginning is lower than certain by the antenna frequencies under force intensity, and when reaching, certain by during force intensity, it will rise.Such force sensitive device used in the present invention has: pressure drag type pressure sensor, piezoelectric pressure sensor, piezoelectric type device for measuring force, piezoelectric type acceleration pick-up unit, macromolecular material piezoelectric sensing device, resonance sensor, type vibration wire pressure sensitive device, vibration cylinder type pressure sensitive device, diaphragm-vibrating type pressure sensitive device, inductance type pressure sensitive device, air gap inductance formula pressure sensitive device, inductance type oil pressure sensor, torque detecting apparatus etc.
Type based on force sensitive device is different, the scope by force intensity may to be a specific stress value also may be a selectively stress value causing changing.The length of time must cause the change of antenna resonance frequency, and antenna quality also can cause different changes.Such as, on antenna with the type of force sensitive device can affect the length changing antenna resonance frequency required time.
As shown in Figure 2, be the equivalent circuit diagram of RFID label antenna.When 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 is just similar to transformer.Both coils are equivalent to primary coil and the secondary coil of transformer.As shown in Figure 2, comprise the coil inductance (L) of label antenna, stray capacitance (Cp) and shunt capacitance (C2), its resonance frequency is the resonant tank formed by label antenna
in formula, C is the parallel equivalent electric capacity of Cp and C2, and R1, R2 are the equivalent resistance of circuit internal inductance coil and other devices.The carrier frequency that label and read write line two-way communication use is exactly f.When requiring that tag antenna coil profile is very little, namely area is little, and need certain operating distance, RFID label tag and the read write line aerial coil mutual induction amount of asking just obviously can not practical requirement, the Ferrite Material with high permeability can be inserted in tag antenna coil inside, to increase mutual induction amount, thus the problem that compensating coil xsect is little.
As shown in Figure 3, for embodiment of the present invention force sensitive device, control the schematic diagram that the logical circuit of break-make and electric piezo-resistive conversion equipment be connected with RFID label antenna equivalent electrical circuit.As shown in the figure, comprise the coil inductance (L) of label antenna, stray capacitance (Cp) and shunt capacitance (C2), its resonance frequency is the resonant tank formed by label antenna
formula C is the parallel equivalent electric capacity of Cp and C2, and R1, R2 are the equivalent resistance of circuit internal inductance coil and other devices.M is the variable resistor representing force sensitive device, and S is the logical circuit controlling break-make, and R3 is the equivalent resistance of connecting with force sensitive device, and F is electric piezo-resistive conversion equipment.When logical circuit disconnects, force sensitive device not with sky line parallel, if now sensor is under pressure, the first resonant frequency of antenna and signal intensity remain unchanged.When logical circuit is connected, force sensitive device and sky line parallel, if now sensor is under pressure, antenna features frequency and signal intensity at least have one and change, and now Antenna Operation is under the second resonant frequency.
As shown in Figure 4, be the schematic diagram that embodiment of the present invention force sensitive device is directly connected with RFID label antenna, the sketch of the passive RFID tags device 40 of the change of pressure can be detected.As shown in Figure 4, label apparatus 40 comprises a base 45, integrated circuit 43 and a double-doublet antenna 41,42.The force sensitive device 44 be connected with antenna 42 will affect the resistance of antenna 42.Force sensitive device 44 the material that is suitable for can according to antenna 41, the current voltage of any in 42 controls any one frequency of both having fixed a point.With regard to an example, fix up an aerial wire 41,42 can make its identical frequency produce resonance.With regard to another example, fix up an aerial wire 41,42 can make its different frequencies produce resonance.
In an example, transmitting terminal antenna 41,42 is made up of one or more different low electrical resistant materials, and these materials have higher electric conductivity, such as copper, silver, and aluminium, they are connected with the above-mentioned force sensitive device mentioned, when antenna 41,42 are placed on that certain force sensitive device can cause the change of one or more transmitting terminal generation resonant frequency by under force intensity, thus cause a different frequency.The frequency of the change of this frequency and reception and transmission is all different.Such as, force sensitive device is positioned over certain under force intensity, will cause in transmission frequency and receive frequency that at least one changes.
In another example, the antenna frequencies value set at the beginning by higher than the antenna frequencies under certain force environment, then when reach certain stressed time, it will reduce.In another example, the antenna frequencies set at the beginning is lower than certain by the antenna frequencies under force intensity, and when reaching, certain by during force intensity, it will rise.Such force sensitive device used in the present invention has: pressure drag type pressure sensor, piezoelectric pressure sensor, piezoelectric type device for measuring force, piezoelectric type acceleration pick-up unit, macromolecular material piezoelectric sensing device, resonance sensor, type vibration wire pressure sensitive device, vibration cylinder type pressure sensitive device, diaphragm-vibrating type pressure sensitive device, inductance type pressure sensitive device, air gap inductance formula pressure sensitive device, inductance type oil pressure sensor, torque detecting apparatus etc.
Type based on force sensitive device is different, the scope by force intensity may to be a specific stress value also may be a selectively stress value causing changing.The length of time must cause the change of antenna resonance frequency, and antenna quality also can cause different changes.Such as, on antenna with the type of force sensitive device can affect the length changing antenna resonance frequency required time.
As shown in Figure 5, the unidirectional force cell of piezoelectric type is made up of quartz wafer 51, insulation sleeve 52, electrode 53, upper cover 54 and pedestal 55.The upper cover of sensor is force transfer element, its outer rim wall thickness 0.1 ~ 0.5mm, and when External Force Acting, it is by generation elastic deformation and power be delivered on quartz wafer.Quartz wafer is of a size of & 8mm*1mm, and it is located by insulation sleeve.The dynamometry scope of this sensor is 0 ~ 50N, and minimum resolution is 0.01N.Natural frequency is 50 ~ 60kHz..The principle of work of piezoelectric transducer is the piezoelectric effect based on producing electric charge after the stressed F of some crystal 51 on its surface.Common piezoelectric 51 has the polycrystalline ceramics (as barium titanate, zirconium metatitanic acid etc.) of quartz crystal, Prof. Du Yucang.The piezoelectric property of piezoelectricity original paper represents with piezoelectric modulus, and because piezoelectric crystal exists anisotropy, in order to distinguish the direction of Impact direction and crystal generation electric charge, general employing marks the leftover bits and pieces of piezoelectric modulus symbol d.Conventional 1,2,3 directions representing x, y, z three axles respectively, and represent tangential effect around x, y, z three axis with 4,5,6.The order of subfix, first is Impact direction, and second is the direction producing electric charge.Namely such as dzz represents stressed in the z-axis direction and produce electric charge in the plane perpendicular to z-axis direction.
As shown in Figure 6, be a kind of method flow diagram of the present invention by using the label apparatus of multiple antennas to detect stressed change.Need it is contemplated that, the above-mentioned device mentioned uses a label integrated circuit to carry out and the exchanging of multiple antenna.
As shown in Figure 6,50, RFID reader sends energy and instruction to label apparatus.52, logical circuit is in the state of disconnection at initial time, label apparatus the antenna received energy be not connected with force sensitive device and instruction.54, label apparatus is converted into DC(direct current the electromagnetic wave carrying energy) voltage, thus label just can be made to perform the requirement of instruction.And this conversion needs to use a charge pump, a rectification circuit, or be interconnected, or other energy conversion device will be used.56, label apparatus sends signal by the sky alignment reader be not connected with force sensitive device.58, reader is measured and is recorded the energy intensity receiving signal.60, reader sends the instruction of connecting logical circuit to label apparatus.62, the label apparatus antenna be connected with force sensitive device sends data.64, reader measurement receives the energy intensity of signal.66, reader calculated goes out the fiducial value of a reflected signal intensity.68, fiducial value is changed into different stressed intensity levels by reader.With regard to an example, reader can set the signal that a time period is used for receiving label, if do not receive signal, signal intensity will be recorded as 0 by reader.
In this system, reader is using the signal strength values from the antenna be not connected with force sensitive device as a reference value, and the signal strength values of the label antenna that it is connected with force sensitive device compares.By receive from being connected with force sensitive device and the signal of the transmitting terminal be not connected with force sensitive device, reader can collect the fiducial value representing unlike signal intensity.Then, RFID reader can such fiducial value be converted into residing for label by force intensity.With regard to a concrete example, configuring this RFID reader is in order to by using the reference data that stores that the difference of RF signal intensity from the antenna connecting or do not connect force sensitive device received is converted into stress value.
Best situation is, using not connecting the antenna of force sensitive device as a reference, the change caused can be filtered out due to the coupling between label and reader.In addition, as previously mentioned, force sensitive device be applied in design the change of the resistance value that can make it and label be placed on specific stressed under time length form relation one to one.Such as, force sensitive device is only positioned on an antenna, the signal from RFID label tag device can be allowed like this to change within the specific limits as a kind of function, and this function just antenna be placed on certain stressed under time after the function that just has.The same, the application of the invention, under the condition that RFID label tag is passive, it is certain stressed lower and within the acceptable range whether this stressed that RFID reader can detect whether label apparatus has been placed.
Do not use the various RFID label tag of two antennas also can perceive stressed change with force sensitive device, the stressed change of perception also can recognize based on the change of resonant frequency on antenna the change that antenna receives signal.
Such as by the design to the antenna be connected with force sensitive device, the frequency of antenna can be made at ISM(IndustrialScientificMedical, industry, science, medical science) the interior change of frequency range, the label of standard can connect this antenna be connected with force sensitive device and logical circuit.
Such as in a concrete example, label antenna can so set, before being exposed in certain force environment, the resonant frequency of antenna is 902-928MHZ, but label is once be exposed in certain force environment, due to stressed impact, the resonant frequency of antenna just reduces to 899.5-927.5MHZ, 52 channels are split at the frequency bins (902-928MHZ) of U.S. RFID, 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 can attempt the conflict that uses same frequency to cause by the multiple reader of effectively preventing in same physical space.
Such as in one example in which, RFID frequency range (902-928MHZ) is not be divided into 52 channels but the antenna settings being on average divided into n channel tag carries out work under this frequency range (902-928MHZ).Because label antenna is connected with force sensitive device, as long as so the stressed scope having exceeded the value preset, the frequency of operation of antenna tag antenna just drops among (899.5-927.5MHZ) this frequency range.Therefore just got rid of from band limits by channel n compared with original frequency range and go, the frequency range (899.5-927.5MHZ) therefore after change carries out exchanging of information with regard to no longer allowing label with channel n.
In concrete example, if the environment at label place has exceeded the field of load of expection, reader can only send instruction by channel 1 to n-1 to label, label also can be made a response, because the antenna in label just can only at this frequency ranges of operation, when reader sends instruction with the frequency of n channel to label, because the stressed change of label has caused the resonant frequency of label antenna to drop to 899.5-927.5MHZ, no longer reach 928MHZ so label is just no longer made a response, pass information back reader.
Favourable aspect is the change due to the stressed operating frequency of antenna caused beyond the value preset, and is just reflected by the disappearance of this information interchange.
In a model, reader can send an instruction between channel n-1 and channel n to label and check that the operating frequency range of label antenna there occurs drift further, because label can receive the instruction sent by channel n-1, and can pass through channel n-1 can to reader feedback information, because label can not receive the instruction sent by channel n, and can not pass through channel n can to reader feedback information, and the operating frequency range so just determining label antenna there occurs drift.
Stressed change causes the frequency of operation of label antenna that drift up and down occurs and the present invention is not limited in frequency range is on average divided into n channel.
The embodiment of the present invention can detect the change of pressure at lower cost, and the energy utilizing RFID to obtain, solve the powerup issue of stressed detection.
The enforcement of each feature of this system may relate to software, the combination that hardware also may relate to software and hardware just can reach, and the enforcement of many advantages of such as system is realized with the mutual mode exchanged of other equipment machines with computer with OO programming language with a kind of high-caliber process by programming.Each such function program may be stored in a storage intermediary to be read by a computer and processor in such as ROM (read-only memory) and realize above-mentioned function.
Those skilled in the art can also recognize the various illustrative components, blocks (illustrativelogicalblock) that the embodiment of the present invention is listed, unit, and step can pass through electronic hardware, computer software, or both combinations realize.For the replaceability (interchangeability) of clear displaying hardware and software, above-mentioned various illustrative components (illustrativecomponents), unit and step have universally described their function.Such function is the designing requirement realizing depending on specific application and whole system by hardware or software.Those skilled in the art for often kind of specifically application, can use the function described in the realization of various method, but this realization can should not be understood to the scope exceeding 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 also can be any traditional processor, controller, microcontroller or state machine.Processor also can be realized by the combination of calculation element, such as digital signal processor and microprocessor, multi-microprocessor, and a Digital Signal Processor Core combined by one or more microprocessor, or other similar configuration any realizes.
The software module that method described in the embodiment of the present invention or the step of algorithm directly can embed hardware, processor performs or the combination of both.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, with make processor can from storage medium reading information, and write information can be deposited 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 design, the above-mentioned functions described by the embodiment of the present invention can realize in the combination in any of hardware, software, firmware or this three.If realized in software, these functions can store on the medium with computer-readable, or are transmitted on the medium of computer-readable with one or more instruction or code form.Computer readable medium comprises computer storage medium and is convenient to make to allow computer program transfer to the telecommunication media in other place from a place.Storage medium can be that any general or special computer can the useable medium of access.Such as, 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 may be used for carrying or store the medium that can be read the program code of form with instruction or data structure and other by general or special computer or general or special processor.In addition, any connection can be properly termed computer readable medium, such as, if software is by a concentric cable, optical fiber computer, twisted-pair feeder, Digital Subscriber Line (DSL) or being also comprised in defined computer readable medium with wireless way for transmittings such as such as 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 magnetic duplication data, and video disc carries out optical reproduction data with laser usually.Above-mentioned combination also can be included in computer readable medium.
Above-described embodiment; object of the present invention, technical scheme and beneficial effect are further described; be 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 amendment made, equivalent replacement, improvement etc., all should be included within protection scope of the present invention.
Claims (6)
1. the RFID label tag with force sensitive device, is characterized in that, the chip of described RFID label tag has two pins, described force sensitive device and this two pins are connected, and form parallel-connection structure with the antenna of described RFID label tag, the extraneous change by force intensity can cause the change of force sensitive device both end voltage or electric current, the circuit that described force sensitive device is connected with the chip of RFID label tag has logical circuit and an electric piezo-resistive conversion equipment controlling break-make, the circuit of this connection, this logical circuit and this electric piezo-resistive conversion equipment are parts for chip, electricity piezo-resistive conversion equipment is for converting the change of resistance to by the change of force sensitive device both end voltage or electric current, the break-make of logical circuit determine force sensitive device whether with sky line parallel: when logical circuit disconnects, force sensitive device not with sky line parallel, if now sensor is under pressure, first resonant frequency of antenna and signal intensity remain unchanged, when logical circuit is connected, force sensitive device and sky line parallel, if now sensor is under pressure, the characteristic frequency of antenna and signal intensity at least have one and change, and now Antenna Operation is under the second resonant frequency, described RFID label tag receives instruction that RFID reader sends with the break-make of control logic circuit, thus realizes the change being detected pressure by the difference between comparing from the signal intensity of the different frequency of antenna, the antenna of described RFID label tag is monopole antenna or double-doublet antenna,
Wherein, when the antenna of described RFID label tag enters in the alternating magnetic field of RFID reader generation, transformer is formed between the antenna of described RFID label tag and the antenna of RFID reader, with thinking that force sensitive device provides energy source, the antenna of RFID label tag and the antenna of RFID reader are respectively primary coil and the secondary coil of transformer;
Described force sensitive device is the unidirectional force cell of piezoelectric type, the unidirectional force cell of described piezoelectric type is made up of piezoelectricity original paper, insulation sleeve, electrode, upper cover and pedestal, upper cover is force transfer element, when External Force Acting, force transfer element is delivered on piezoelectricity original paper by generation elastic deformation and by power, piezoelectricity original paper is located by insulation sleeve, the principle of work of piezoelectric transducer be stressed based on piezoelectricity original paper after to produce the piezoelectric effect of electric charge on its surface;
The Ferrite Material of high permeability is inserted at the inner antenna of described RFID label tag.
2. be with the RFID label tag of force sensitive device as claimed in claim 1, it is characterized in that, when the antenna of described RFID label tag is double-doublet antenna: described force sensitive device and the electric piezo-resistive conversion equipment that is connected with this force sensitive device and a wherein antenna form parallel-connection structure; Or described force sensitive device and the electric piezo-resistive conversion equipment be connected with this force sensitive device and two antennas form parallel-connection structure simultaneously.
3. the RFID label tag with force sensitive device, is characterized in that, the chip of described RFID label tag has a pin, one end of described force sensitive device is connected with this pin, the other end is connected on the antenna of described RFID label tag, and form parallel-connection structure with antenna, the extraneous change by force intensity can cause the change of force sensitive device both end voltage or electric current, the circuit that described force sensitive device is connected with the chip of RFID label tag has logical circuit and an electric piezo-resistive conversion equipment controlling break-make, the circuit of this connection, this logical circuit and this electric piezo-resistive conversion equipment are parts for chip, electricity piezo-resistive conversion equipment is for converting the change of resistance to by the change of force sensitive device both end voltage or electric current, the break-make of logical circuit determine force sensitive device whether with sky line parallel: when logical circuit disconnects, force sensitive device not with sky line parallel, if now sensor is under pressure, first resonant frequency of antenna and signal intensity remain unchanged, when logical circuit is connected, force sensitive device and sky line parallel, if now sensor is under pressure, the characteristic frequency of antenna and signal intensity at least have one and change, and now Antenna Operation is under the second resonant frequency, described RFID label tag receives instruction that RFID reader sends with the break-make of control logic circuit, thus realizes the change being detected pressure by the difference between comparing from the signal intensity of the different frequency of antenna, the antenna of described RFID label tag is monopole antenna or double-doublet antenna,
Wherein, when the antenna of described RFID label tag enters in the alternating magnetic field of RFID reader generation, transformer is formed between the antenna of described RFID label tag and the antenna of RFID reader, with thinking that force sensitive device provides energy source, the antenna of RFID label tag and the antenna of RFID reader are respectively primary coil and the secondary coil of transformer;
Described force sensitive device is the unidirectional force cell of piezoelectric type, the unidirectional force cell of described piezoelectric type is made up of piezoelectricity original paper, insulation sleeve, electrode, upper cover and pedestal, upper cover is force transfer element, when External Force Acting, force transfer element is delivered on piezoelectricity original paper by generation elastic deformation and by power, piezoelectricity original paper is located by insulation sleeve, the principle of work of piezoelectric transducer be stressed based on piezoelectricity original paper after to produce the piezoelectric effect of electric charge on its surface;
The Ferrite Material of high permeability is inserted at the inner antenna of described RFID label tag.
4. be with the RFID label tag of force sensitive device as claimed in claim 3, it is characterized in that, when the antenna of described RFID label tag is double-doublet antenna: described force sensitive device and the electric piezo-resistive conversion equipment that is connected with this force sensitive device and a wherein antenna form parallel-connection structure; Or described force sensitive device and the electric piezo-resistive conversion equipment be connected with this force sensitive device and two antennas form parallel-connection structure simultaneously.
5. the rfid system with force sensitive device, described rfid system comprises RFID label tag and RFID reader, it is characterized in that,
Described RFID label tag comprises the RFID label tag with force sensitive device according to any one of claim 1-2, or the RFID label tag with force sensitive device according to any one of claim 3-4;
Described RFID reader sends instruction to control the break-make of the logical circuit of RFID label tag, thus detects the change of pressure by the difference between comparing from the signal intensity of the different frequency of antenna.
6. a stressed detection method for the rfid system with force sensitive device, is characterized in that, described stressed detection method is applied to the rfid system with force sensitive device described in claim 5, comprising:
Instruction is sent to control the break-make of the logical circuit of RFID label tag by described RFID reader;
The instruction of RFID reader transmission is received with the break-make of control logic circuit: when logical circuit disconnects by RFID label tag, force sensitive device not with sky line parallel, if now sensor is under pressure, the first resonant frequency of antenna and signal intensity remain unchanged; When logical circuit is connected, force sensitive device and sky line parallel, if now sensor is under pressure, the characteristic frequency of antenna and signal intensity at least have one and change, and now Antenna Operation is under the second resonant frequency;
Utilize described RFID reader to compare from the signal intensity of the different frequency of antenna between difference to detect the change of pressure.
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| CN112816108B (en) * | 2020-12-31 | 2023-03-21 | 隔空（上海）智能科技有限公司 | Pressure detection circuit and detection method based on amplitude detection and earphone |
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