CN110132320A - The method for monitoring capacitance type sensor capacitance variations - Google Patents
The method for monitoring capacitance type sensor capacitance variations Download PDFInfo
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- CN110132320A CN110132320A CN201910509742.XA CN201910509742A CN110132320A CN 110132320 A CN110132320 A CN 110132320A CN 201910509742 A CN201910509742 A CN 201910509742A CN 110132320 A CN110132320 A CN 110132320A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
- G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
- G01D5/12—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means
- G01D5/14—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage
- G01D5/24—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage by varying capacitance
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Abstract
The method of monitoring capacitance type sensor capacitance variations of the present invention, mainly the standard capacitance Cs known to single-chip microcontroller and capacity with AD/IO Multifunctional mouth is formed the observation circuit used, one AD/IO mouthfuls of one end of standard capacitance Cs known to capacity and the single-chip microcontroller are connect, and the other end of standard capacitance Cs known to capacity is connect with an I/O port of the single-chip microcontroller or another AD/IO mouthfuls.When monitoring the capacitance variations of capacitance type sensor, there are three types of mode, the operating procedure for monitoring capacitance type sensor capacitance variations is determined according to the connection connection type of capacitance type sensor and the observation circuit for the connection of capacitance type sensor and the observation circuit.The method of the invention enormously simplifies circuit structure under the premise of ensuring the monitoring accuracy to capacitance variations, reduces costs, and improves stability.
Description
Technical field
The invention belongs to capacitance type sensor fields, in particular to monitor the method for capacitance type sensor capacitance variations.
Background technique
Capacitance type sensor is a kind of conversion equipment that measurand is converted into electric capacitance change, due to having knot
The advantages that structure is simple, high temperature resistant, radiation hardness, high resolution, dynamic response characteristic are good, thus it is widely used in liquid level, thickness, pressure
In the measurement such as power, displacement, acceleration, vibration.
The use of capacitance type sensor be unable to do without the circuit and method for monitoring its capacitance variations.In the prior art, has prison
The special chip of (or detection) capacitance type sensor capacitance variations is surveyed, such as: PCAP01, AD7745, AD7746, FDC1004.But
The cost of manufacture or acquisition cost of device or device that monitoring capacitance type sensor capacitance variations are made of this class special chip are very
Height, for example, widely used capacitive approach switch is exactly that one kind monitors moving object position based on capacitance type sensor principle
The device for setting variation, due to cost problem, current capacitive approach switch generally uses the oscillating circuit of resolution element composition
The capacitance variations of sensor are monitored, the price of the capacitive approach switch based on this circuit capacitance detecting core more dedicated than one
Piece also wants low, but the sensitivity of this kind of capacitive approach switch is related to the material of monitored target, therefore brings to its application
It is inconvenient.
CN 2,017 2 0584516.4 discloses the capacitance type liquid level inspection for the liquid level height that monitoring conductivity is not zero
Slowdown monitoring circuit, the circuit include single-chip microcontroller, operational amplifier, the first analog switch, standard known to the second analog switch and capacity
Capacitor.The circuit is used cooperatively with capacitance level transducer, although effectively eliminating the conductivity of monitored liquid level not
The equivalent impedance uncertainty adverse effect caused by liquid level monitoring result for the liquid for being zero, is greatly improved liquid level
Application has successfully been obtained in the monitoring accuracy of height in the water level monitoring of intelligence rice humidifier, and cost drops compared with special chip
It is low, but the device in its circuit structure is still more, and higher to the performance requirement of amplifier and analog switch, these not only influence production
Cost, and affect the consistency and stability of monitoring accuracy.
Summary of the invention
It is an object of the invention to overcome the deficiencies of the prior art and provide the more simplified monitoring condenser type biographies of circuit structure
The method of sensor capacitance variations expands application range to further increase performance, reduce cost.
The method of monitoring capacitance type sensor capacitance variations of the present invention, the observation circuit used is mainly by having AD/
The composition of standard capacitance Cs known to the single-chip microcontroller and capacity of IO Multifunctional mouth, one end of standard capacitance Cs known to capacity with it is described
AD/IO mouthfuls of connections for single-chip microcontroller, the other end of standard capacitance Cs and an I/O port of the single-chip microcontroller known to capacity or
Another AD/IO mouthfuls of connection.
The method of monitoring capacitance type sensor capacitance variations of the present invention, principle are as follows: first in observation circuit
Single-chip microcontroller is with the variation of the port status connecting of the monitored capacitor Cx in standard capacitance Cs and capacitance type sensor to the quilt
Capacitor Cx charging is monitored, and sets the voltage Vcx=Vcc at the monitored both ends capacitor Cx after charging complete, then passes through monitoring electricity again
Single-chip microcontroller makes Cx with the variation of the port status connecting of the monitored capacitor Cx in standard capacitance Cs and capacitance type sensor in road
In pass through charging obtain charge Q=VCC× Cx is shifted to the standard capacitance Cs, by latter two capacitor of time Δ T
Voltage is equal (reaching equilibrium state), and the voltage at the both ends Cs or Cx after being up to equilibrium state is denoted as Vcs, then Vcs and institute
State the relationship between charge Q are as follows:
Vcs=Q/ (Cs+Cx)=VCC×Cx/(Cs+Cx)
As available from the above equation:
It is of the present invention monitoring capacitance type sensor capacitance variations method be suitable for all kinds of capacitance type sensors, below with
The capacitance type liquid level of the liquid level for the liquid that the observation circuit and monitoring conductivity that the present invention shown in fig. 5 uses are not zero passes
The equivalent circuit of sensor is illustrated.In fact, the capacitor in capacitance level transducer is by two conductive plates and to be clipped in
What the medium between two conductive plates was constituted, the monitored capacitor Cx in equivalent circuit is the capacitor changed with liquid level.
In the inside for detecting the capacitance level transducer that liquid level changes, the one of first electrode 4-1 and monitored capacitor Cx
A metal polar plate connection, the medium for constituting monitored capacitor Cx are wrapped on this metal polar plate, second electrode 4-2 and a gold
Belong to conductor connection, after capacitance level transducer insertion monitored liquid, the appearance of the medium as monitored capacitor Cx
The liquid that face is not zero by conductivity surrounds, and the liquid for being enclosed in monitored capacitor Cx media inside surface constitutes monitored capacitor Cx
Another pole plate, submerging the metallic conductor connecting with second electrode 4-2 in a liquid, (i.e. Cx's is another with monitored liquid
One pole plate) connection, Rx is to be enclosed in the liquid of monitored capacitor Cx media inside surface to the metal connecting with second electrode 4-2
Equivalent resistance between conductor.The parameters such as the value of Rx and the ingredient of liquid medium, temperature are related, have uncertainty, it is influenced
Time Δ T needed for reaching equilibrium state to the charge and discharge of monitored capacitor Cx and electric charge transfer in monitoring process, but its not shadow
The monitoring accuracy of the method for the invention is rung, as Rx=0, the sensor in Fig. 5 is just at the capacitance type sensor of broad sense, institute
With the method for monitoring capacitance type sensor capacitance variations of the present invention is suitable for all kinds of capacitance type sensors.
The method of monitoring capacitance type sensor capacitance variations of the present invention, in the capacitance variations of monitoring capacitance type sensor
When, capacitance type sensor is connected with following three kinds of modes with the observation circuit:
First way, by the first electrode of capacitance type sensor and observation circuit acceptance of the bid pseudo-capacitance Cs and single-chip microcontroller
The connection of AD/IO mouth contact connection, by the ground connection of single-chip microcontroller in the second electrode of capacitance type sensor and the observation circuit
Contact connection.
The second way, by the first electrode of capacitance type sensor and observation circuit acceptance of the bid pseudo-capacitance Cs and single-chip microcontroller
The connection of AD/IO mouth contact connection, single-chip microcontroller in the second electrode of capacitance type sensor and the observation circuit is connect into electricity
The contact in source connects.
The third mode, by the first electrode of capacitance type sensor and observation circuit acceptance of the bid pseudo-capacitance Cs and single-chip microcontroller
AD/IO mouth connection contact connection, the second electrode of capacitance type sensor and single-chip microcontroller in the observation circuit are not made
I/O port or AD/IO mouthfuls of connections.
Based on different connection types, the operating procedure for monitoring capacitance type sensor capacitance variations is different.
1, when the connection of capacitance type sensor and the observation circuit is first way, monitoring capacitance type sensor electricity
Hold the operating procedure of variation are as follows:
1. setting delivery outlet for two ports that the single-chip microcontroller in observation circuit is connected with the both ends standard capacitance Cs, and will
They are set to high level Vcc simultaneously, which forces the both ends standard capacitance Cs equipotential to make the charge zero in standard capacitance Cs
Make the first electrode high level Vcc for the capacitance type sensor connecting with the AD/IO of single-chip microcontroller mouth simultaneously, and then passes through the first electricity
Monitored capacitor Cx charging of the pole into capacitance type sensor, as the voltage V at the monitored both ends capacitor CxCXIt is charged to VCX=
VCCAfterwards, being monitored the quantity of electric charge that capacitor Cx is injected is Q=VCC×Cx；
2. the AD/IO that the single-chip microcontroller in observation circuit is connect with the first electrode of standard capacitance Cs and capacitance type sensor
Mouth is arranged to AD mouthfuls, while what single-chip microcontroller was connect with the standard capacitance Cs other end sets in the I/O port or AD/IO mouthful of output state
For low level 0, which makes the first electrode of standard capacitance Cs and capacitance type sensor in observation circuit, second electrode in simultaneously
It connection state and jumps to standard capacitance Cs between the AD mouth of single-chip microcontroller and ground, makes monitored capacitor Cx in last action step
Standard capacitance Cs transfer of the charge Q of acquisition into observation circuit；
3. the charge of standard capacitance Cs transfer of the monitored capacitor Cx in capacitance type sensor into observation circuit reaches
After equilibrium state, starts the AD conversion function of single-chip microcontroller in observation circuit, measure described AD mouthfuls of voltage VAD, 2. due to step
Operation is connected across standard capacitance Cs between the AD mouth of single-chip microcontroller and ground, then the voltage Vcs=V at the both ends standard capacitance CsAD, will
Vcs substitutes into following formula
The value of monitored capacitor Cx can be obtained.
2, when the connection of capacitance type sensor and the observation circuit is the second way, monitoring capacitance type sensor electricity
Hold the operating procedure of variation are as follows:
1. setting delivery outlet for two ports that the single-chip microcontroller in observation circuit is connected with the both ends standard capacitance Cs, and will
They are set to low level 0 simultaneously, which forces the both ends standard capacitance Cs equipotential to keep the charge zero in standard capacitance Cs same
When make the first electrode low level 0 of the capacitance type sensor connecting with the AD/IO of single-chip microcontroller mouth, and then by with single-chip microcontroller
Monitored capacitor Cx charging of the second electrode of the capacitance type sensor of the contact connection of power supply into capacitance type sensor is connect, when
The voltage V at the monitored both ends capacitor CxCXIt is charged to VCX=VCCAfterwards, being monitored the quantity of electric charge that capacitor Cx is injected is Q=Vcc
×Cx；
2. the AD/IO that the single-chip microcontroller in observation circuit is connected with the first electrode of standard capacitance Cs and capacitance type sensor
Mouth is arranged to AD mouthfuls, at the same by single-chip microcontroller in observation circuit connect with the standard capacitance Cs other end in output state I/O port or
AD/IO mouthfuls are set to high level Vcc, the operation make standard capacitance Cs and capacitance type sensor in observation circuit first electrode,
Second electrode is in parallel connection and jumps to standard capacitance Cs between the power supply of single-chip microcontroller and AD mouthfuls, and monitored capacitor Cx is made to exist
Standard capacitance Cs transfer of the charge Q obtained in last action step into observation circuit；
3. when the charge of standard capacitance Cs transfer of the monitored capacitor Cx in capacitance type sensor into observation circuit reaches
To after equilibrium state, starts the AD conversion function of single-chip microcontroller in observation circuit, measure the voltage V of the port ADAD, 2. due to step
Operation is connected across standard capacitance Cs between the power supply of single-chip microcontroller and AD mouthfuls, then the voltage Vcs=Vcc- at the both ends standard capacitance Cs
VAD, Vcs is substituted into following formula
The value of monitored capacitor Cx can be obtained.
3, when the connection of capacitance type sensor and the observation circuit is the third mode, monitoring capacitance type sensor electricity
Hold the operating procedure of variation are as follows:
1. the I/O port of the second electrode of single-chip microcontroller in observation circuit and capacitance type sensor connection or AD/IO mouthfuls are arranged to
Delivery outlet is simultaneously set to low level 0；
2. setting delivery outlet for two ports that the single-chip microcontroller in observation circuit is connected with the both ends standard capacitance Cs, and will
They are set to high level Vcc simultaneously, which forces the both ends standard capacitance Cs equipotential to make the charge zero in standard capacitance Cs
Make the first electrode high level Vcc for the capacitance type sensor connecting with the AD/IO of single-chip microcontroller mouth simultaneously, and then passes through the first electricity
Monitored capacitor Cx charging of the pole into capacitance type sensor, as the voltage V at the monitored both ends capacitor CxCXIt is charged to VCX=
VCCAfterwards, being monitored the quantity of electric charge that capacitor Cx is injected is Q=VCC×Cx；
3. the AD/IO that the single-chip microcontroller in observation circuit is connect with the first electrode of standard capacitance Cs and capacitance type sensor
Mouth is arranged to AD mouthfuls, while what single-chip microcontroller was connect with the standard capacitance Cs other end sets in the I/O port or AD/IO mouthful of output state
For low level 0, which makes the first electrode of standard capacitance Cs and capacitance type sensor in observation circuit, second electrode in simultaneously
It connection state and jumps to standard capacitance Cs between the AD mouth of single-chip microcontroller and ground, makes monitored capacitor Cx in last action step
Standard capacitance Cs transfer of the charge Q of acquisition into observation circuit；
4. the charge of standard capacitance Cs transfer of the monitored capacitor Cx in capacitance type sensor into observation circuit reaches
After equilibrium state, starts the AD conversion function of single-chip microcontroller in observation circuit, measure described AD mouthfuls of voltage VAD, 3. due to step
Operation is connected across standard capacitance Cs between the AD mouth of single-chip microcontroller and ground, then the voltage Vcs=V at the both ends standard capacitance CsAD, will
Vcs substitutes into following formula
The value of monitored capacitor Cx can be obtained；
Or the operating procedure of monitoring capacitance type sensor capacitance variations are as follows:
1. the I/O port of the second electrode of single-chip microcontroller in observation circuit and capacitance type sensor connection or AD/IO mouthfuls are arranged to
Delivery outlet is simultaneously set to high level Vcc；
2. setting delivery outlet for two ports that the single-chip microcontroller in observation circuit is connected with the both ends standard capacitance Cs, and will
They are set to low level 0 simultaneously, which forces the both ends standard capacitance Cs equipotential to keep the charge zero in standard capacitance Cs same
When make the first electrode low level 0 of the capacitance type sensor connecting with the AD/IO of single-chip microcontroller mouth, and then by with single-chip microcontroller
It is set to second electrode being supervised into capacitance type sensor of the I/O port of high level or the capacitance type sensor of AD/IO mouthfuls of connections
Capacitor Cx charging is surveyed, as the voltage V at the monitored both ends capacitor CxCXIt is charged to VCX=VCCAfterwards, it is monitored what capacitor Cx was injected
The quantity of electric charge is Q=Vcc × Cx；
3. the AD/IO that the single-chip microcontroller in observation circuit is connected with the first electrode of standard capacitance Cs and capacitance type sensor
Mouth is arranged to AD mouthfuls, at the same by single-chip microcontroller in observation circuit connect with the standard capacitance Cs other end in output state I/O port or
AD/IO mouthfuls are set to high level Vcc, the operation make standard capacitance Cs and capacitance type sensor in observation circuit first electrode,
Second electrode is in parallel connection and jumps to standard capacitance Cs between the power supply of single-chip microcontroller and AD mouthfuls, and monitored capacitor Cx is made to exist
Standard capacitance Cs transfer of the charge Q obtained in last action step into observation circuit；
4. when the charge of standard capacitance Cs transfer of the monitored capacitor Cx in capacitance type sensor into observation circuit reaches
To after equilibrium state, starts the AD conversion function of single-chip microcontroller in observation circuit, measure the voltage V of the port ADAD, 3. due to step
Operation is connected across standard capacitance Cs between the power supply of single-chip microcontroller and AD mouthfuls, then the voltage Vcs=Vcc- at the both ends standard capacitance Cs
VAD, Vcs is substituted into following formula
The value of monitored capacitor Cx can be obtained.
When the observation circuit as shown in Figure 1, the standard electric as known to single-chip microcontroller and capacity with AD/IO Multifunctional mouth
When holding Cs composition, if necessary to monitor the mainboard of the device of capacitance type sensor capacitance variations or the single-chip microcontroller band of other feature boards
There is AD/IO Multifunctional mouth, the both ends of the standard capacitance Cs by mode described in Fig. 1 and can be needed to monitor capacitance type sensor electricity
The single-chip microcontroller connection for holding the mainboard or other feature boards of the device of variation, i.e., to need to monitor capacitance type sensor capacitance variations
The single-chip microcontroller of the mainboard of device or other feature boards replaces the single-chip microcontroller with AD/IO Multifunctional mouth in Fig. 1, makes observation circuit
Cost further decrease.
The method of monitoring capacitance type sensor capacitance variations of the present invention, the observation circuit used further includes the first connection
Device, first connector connect Chip Microcomputer A/D/I/O port with standard capacitance Cs known to capacity by the first contained contact
One end connection, is connect by the second contained contact with the contact that single-chip microcontroller is grounded, or pass through the second contained contact and list
The contact connection for connecing power supply of piece machine, or the I/O port being not used by by contained the second contact and single-chip microcontroller or AD/IO mouthfuls
Connection；When monitoring the capacitance variations of capacitance type sensor, by the in the first electrode of capacitance type sensor and the first connector
The connection of one contact, the second electrode of capacitance type sensor is connect with the second contact in the first connector.
The method of monitoring capacitance type sensor capacitance variations of the present invention, the observation circuit used further includes the first connection
Device and the second connector, i.e., as with standard capacitance Cs, the first connector known to the single-chip microcontroller of AD/IO Multifunctional mouth, capacity
Observation circuit module (as shown in Figure 2, Figure 3, Figure 4) is constituted with the second connector；First connector passes through contained first
Contact connect the connection of Chip Microcomputer A/D/I/O port one end with standard capacitance Cs known to capacity, passes through the second contained contact and list
The contact connection of piece machine ground connection, is perhaps connected or is passed through by the contact for connecing power supply of contained the second contact and single-chip microcontroller
I/O port that the second contained contact and single-chip microcontroller are not used by or AD/IO mouthfuls are connect；Second connector passes through contained the
One contact, the second contact, third contact, the 4th contact, the 5th contact send mouth, communication with the power supply of single-chip microcontroller, communication respectively
Receiving port, the contact connection for resetting mouth and ground connection；When monitoring the capacitance variations of capacitance type sensor, by the of capacitance type sensor
One electrode is connect with the first contact in the first connector, by the in the second electrode of capacitance type sensor and the first connector
Two point connection.
The method of monitoring capacitance type sensor capacitance variations of the present invention, has the advantages that
1, compared with the capacitance type liquid level detection circuit that CN 2,017 2 0584516.4 is provided, the method for the invention exists
Ensure to enormously simplify circuit structure under the premise of the monitoring accuracy to capacitance variations, reduce costs, improves stability.Such as
It is multi-functional that the single-chip microcontroller of mainboard or other feature boards that fruit needs to monitor the device of capacitance type sensor capacitance variations has AD/IO
Mouthful, monitoring can be replaced with the single-chip microcontroller of the mainboard for the device for needing to monitor capacitance type sensor capacitance variations or other feature boards
The single-chip microcontroller with AD/IO Multifunctional mouth in circuit, further decreases the cost of observation circuit.
2, the method for the invention, the monitoring of capacitance variations, cannot be only used for liquid suitable for all kinds of capacitance type sensors
Position monitoring, it may also be used for the monitoring of the physical quantitys such as position, displacement, thickness, pressure or parameter.In most applications, with it is current
Special chip compare, cost, which can drop, to be several times lower than or even tens times.By in the industry it is widely applied close to switch for, for reduce at
This, the oscillating circuit that the circuit of the detection capacitance variations of current capacitive approach switch generally uses discrete component to constitute comes real
Existing, the entire market price close to switch is far below the price of a dedicated capacitance detecting chips.This lacking close to switch
Point is, after sensitivity adjustment is fixed, perceives the widely different of the position (or distance) of the monitored target of different materials, and base
Have the function of intellectual monitoring in observation circuit provided by the invention, can with the capacitance maximum occurred in capacitor change procedure come
The position of corresponding monitored target, keeps positioning accuracy unrelated with the material of monitored target, and positioning accuracy is much higher than to use and divide
From element composition close to switch, and its cost is suitable with the cost of the observation circuit of existing capacitive approach switch.
Detailed description of the invention
Fig. 1 is the first knot for the observation circuit that the method for monitoring capacitance type sensor capacitance variations of the present invention uses
Structure schematic diagram；
Fig. 2 is second of knot of the observation circuit that the method for monitoring capacitance type sensor capacitance variations of the present invention uses
Structure schematic diagram；
Fig. 3 is three kinds of structures of the observation circuit that the method for monitoring capacitance type sensor capacitance variations of the present invention uses
Schematic diagram；
Fig. 4 is the 4th kind of knot of the observation circuit that the method for monitoring capacitance type sensor capacitance variations of the present invention uses
Structure schematic diagram；
Fig. 5 is the schematic illustration of the method for building monitoring capacitance type sensor capacitance variations of the present invention；
Fig. 6 is the circuit diagram for the liquid level height being not zero using the method for the invention monitoring conductivity；
Fig. 7 is the circuit diagram using the capacitive approach switch of the method for the invention monitoring object position；
Fig. 8 is the mechanical structure schematic diagram of capacitive approach switch and the opposite position of capacitive approach switch and testee
Set schematic diagram.
In figure, the 1-single-chip microcontroller with AD/IO Multifunctional mouth, the 2-the first connector, the first of the first connector of 2-1-
Contact, the second contact of the first connector of 2-2-, the 3-the second connector, the first contact of the second connector of 3-1-, 3-2-
Second contact of the second connector, the third contact of the second connector of 3-3-, the 4th contact of the second connector of 3-4-, 3-
5th contact of the 5-the second connector, 4-capacitance type sensors, 4-1-capacitance type sensor first electrode, 4-2-capacitor
The second electrode of formula sensor, the connector of 5-humidifier master control borads, 6-close switches, 6-1-circuit board, 6-2-metal
Shield shell, 6-3-sheet metal, 7-testees.
Specific embodiment
The method of monitoring capacitance type sensor capacitance variations of the present invention is made by way of example and in conjunction with the accompanying drawings
It further illustrates.
In following embodiments, single-chip microcontroller, the first connector and the second connector can be bought by market.
Embodiment 1
The height of water level of the present embodiment real-time monitoring humidifier changes, and uses the single-chip microcontroller by having AD/IO Multifunctional mouth
1, the observation circuit module of standard capacitance Cs known to capacity, the first connector 2 and the second connector 3 composition, as shown in Figure 6；
The model N76E003 of single-chip microcontroller 1, the P1.1 mouth of single-chip microcontroller be AD/IO Multifunctional mouth, P1.2 mouthfuls be input and output I/O port, mark
Pseudo-capacitance Cs is the NPO capacitor of capacity 100P, and the first connector 2 and the second connector 3 are that the foot spacing of 2 cores and 5 cores is respectively
2.54mm printed-board receptacle；One end of standard capacitance Cs known to capacity is connect with the P1.1 of single-chip microcontroller mouth, known to capacity
The other end of standard capacitance Cs connect with the P1.2 of single-chip microcontroller mouth；First connector 2 connects by contained first
Point 2-1 connect one end connection of single-chip microcomputer P1.1 mouth with standard capacitance Cs known to capacity, by contained the second contact 2-2 with
The contact connection of single-chip microcontroller ground connection；Second connector 3 is connect by the first contained contact 3-1, the second contact 3-2, third
Point 3-3, the 4th contact 3-4, the 5th contact 3-5 send mouth TXD, communication receiving port with the power Vcc of single-chip microcontroller 1, communication respectively
RXD, it resets mouth RST and is grounded the contact connection of GND.When preparing observation circuit module, the second connector 3 is downloaded for program,
In actual use, the second connector 3 is connect with the connector 5 of humidifier master control borad, observation circuit module and humidifier master control borad
Between interface connection type as shown in fig. 6, by this connection relationship realize humidifier master control borad observation circuit module is mentioned
Power supply source simultaneously carries out data exchange.
The height of water level variation for monitoring humidifier realizes that condenser type passes by the capacitance variations of monitoring capacitance type sensor 4
Sensor 4 is capacitance level transducer, and the equivalent circuit after being inserted into monitored liquid is as shown in fig. 6, monitor the change of its capacitor
When change, the first contact 2-1 in the first electrode 4-1 of capacitance type sensor and the first connector 2 of observation circuit module is connected
It connects, the second electrode 4-2 of capacitance type sensor is connect with the second contact 2-2 in the first connector 2 of observation circuit module.
Monitor the operating procedure of 4 capacitance variations of capacitance type sensor are as follows:
1. setting P1.1 mouth that the single-chip microcontroller 1 in observation circuit module is connected with the both ends standard capacitance Cs and P1.2 mouthfuls to
Delivery outlet, and they are set to high level Vcc simultaneously, which forces the both ends standard capacitance Cs equipotential to make in standard capacitance Cs
Charge be zero while making the first electrode 4-1 high level Vcc for the capacitance type sensor 4 connecting with the P1.1 of single-chip microcontroller 1 mouth,
And then the monitored capacitor Cx charging by first electrode 4-1 into capacitance type sensor, when the electricity at the monitored both ends capacitor Cx
Press VCXIt is charged to VCX=VCCAfterwards, being monitored the quantity of electric charge that capacitor Cx is injected is Q=VCC×Cx；
2. the first electrode 4-1 of single-chip microcontroller 1 and standard capacitance Cs and capacitance type sensor 4 in observation circuit module is connected
The P1.1 mouth connect is arranged to AD mouthfuls, while the P1.2 mouth in output state that single-chip microcontroller 1 is connect with the standard capacitance Cs other end
It is set to low level 0, which makes the first electrode 4-1 of standard capacitance Cs and capacitance type sensor 4 in observation circuit module,
Two electrode 4-2 are in parallel connection and jump to standard capacitance Cs between the AD mouth of single-chip microcontroller 1 and ground, and monitored capacitor Cx is made to exist
Standard capacitance Cs transfer of the charge Q obtained in last action step into observation circuit；
3. passing through time Δ T (the present embodiment takes Δ T=200uS), the monitored capacitor Cx in capacitance type sensor is to prison
After the charge of standard capacitance Cs transfer in slowdown monitoring circuit module reaches equilibrium state, start single-chip microcontroller 1 in observation circuit module
AD conversion function measures P1.1 mouthfuls of voltage VAD, since the operation of step 2. makes standard capacitance Cs be connected across the P1.1 of single-chip microcontroller 1
Mouthful between ground, then the voltage Vcs=V at the both ends standard capacitance CsAD, since the value of Cs, Vcc are it is known that substitute into following formula for Vcs
The value of monitored capacitor Cx can be obtained.
Since the height of water level of humidifier and monitored capacitor Cx are in a linear relationship, by by VADValue and actual height of water level
Value is demarcated, and V can be directly passed throughADValue obtains liquid level height value.
In the present embodiment, the difference in height between the bottom limit level and upper limit level of humidifier is 120mm, full scale monitoring essence
Reachable ± 1% is spent, resolution ratio is up to 0.5mm.
Embodiment 2
The change in location of the present embodiment real-time monitoring object uses the single-chip microcontroller 1 and capacity by having AD/IO Multifunctional mouth
The observation circuit of known standard capacitance Cs composition, as shown in Figure 7.The model N76E003 of single-chip microcontroller 1, the P1.1 of single-chip microcontroller
Mouthful be AD/IO Multifunctional mouth, P1.2 mouthfuls be input and output I/O port, P1.3 mouthfuls be input and output I/O port, standard capacitance Cs is capacity
The NPO capacitor of 10P；One end of standard capacitance Cs known to capacity is connect with the P1.1 of single-chip microcontroller mouth, the known mark of capacity
The other end of pseudo-capacitance Cs is connect with the P1.2 of single-chip microcontroller mouth.The capacitance pole of above-mentioned observation circuit and capacitance type sensor 4
Plate, which is integrated together, constitutes capacitive approach switch 6, as shown in Figure 7, Figure 8.From figure 8, it is seen that close to switch 6 mainly by pacifying
Circuit board 6-1, Metal shielding shell 6-2 and sheet metal 6-3 equipped with observation circuit are constituted, and are equipped with the circuit board of observation circuit
6-1 is located in Metal shielding shell 6-2, and sheet metal 6-3 is mounted at the port Metal shielding shell 6-2.Outside the metallic shield
Shell 6-2 constitutes a pole plate of the monitored capacitor Cx in capacitance type sensor, and sheet metal 6-3 is constituted in capacitance type sensor
Another pole plate of monitored capacitor Cx；Constitute the left and right sides and a left side of the dielectric distribution of monitored capacitor Cx in sheet metal 6-3
The average dielectric constant of side medium with testee 7 with and without and it is remote, close and change, in no testee 7 close to sheet metal
When the outer surface 6-3, the medium on the left of sheet metal 6-3 is that air is located at when testee 7 is close to sheet metal outer surface
Medium on the left of sheet metal 6-3 is mainly testee, since the dielectric that the dielectric constant of testee is greater than air dielectric is normal
Number, thus when testee is close to sheet metal 6-3, the average dielectric constant for being monitored the medium of capacitor Cx increases, so that by
The capacity of monitoring capacitor Cx becomes larger, and corresponds to testee 7 with the capacitance maximum occurred in monitored capacitor Cx change procedure
Position.
In the present embodiment, the operating procedure of monitoring 4 capacitance variations of capacitance type sensor is same as Example 1.
Due to the not influence (Rx=0) of Rx in example 2, so, the response speed of embodiment 2 is much higher than embodiment
1.Electricity is monitored in the capacitance type sensor for constituting capacitive approach switch since method provided by the invention can be monitored in real time
The variation for holding Cx, the position of testee can be corresponded to the capacitance maximum occurred in capacitor change procedure, makes positioning accurate
Spend unrelated with the material of testee, thus its positioning accuracy is much higher than using resolution element composition close to switch.
Claims (5)
1. a kind of method for monitoring capacitance type sensor capacitance variations, it is characterised in that the observation circuit used is mainly by having
Standard capacitance Cs known to the single-chip microcontroller (1) and capacity of AD/IO Multifunctional mouth is formed, one end of standard capacitance Cs known to capacity
It is connect with one AD/IO mouthfuls of the single-chip microcontroller (1), the other end of standard capacitance Cs known to capacity and the single-chip microcontroller (1)
An I/O port or another AD/IO mouthfuls connection；
When monitoring the capacitance variations of capacitance type sensor, by the first electrode (4-1) of capacitance type sensor (4) and monitoring electricity
The contact connection that road acceptance of the bid pseudo-capacitance Cs is connect with the AD/IO mouth of single-chip microcontroller (1), by the second electrode of capacitance type sensor (4)
(4-2) is connect with the contact of the ground connection of single-chip microcontroller (1) in the observation circuit；
Monitor the operating procedure of capacitance type sensor capacitance variations are as follows:
1. setting delivery outlet for two ports that the single-chip microcontroller (1) in observation circuit is connected with the both ends standard capacitance Cs, and will
They are set to high level Vcc simultaneously, which makes the charge zero in standard capacitance Cs, and make to be monitored in capacitance type sensor
The quantity of electric charge that capacitor Cx is injected is Q=VCC×Cx；
2. the single-chip microcontroller (1) in observation circuit is connect with the first electrode (4-1) of standard capacitance Cs and capacitance type sensor (4)
AD/IO mouth be arranged to AD mouthfuls, while by single-chip microcontroller (1) connect with the standard capacitance Cs other end in output state I/O port or
AD/IO mouthfuls are set to low level 0, and the charge Q which obtain monitored capacitor Cx in last action step is to observation circuit
In standard capacitance Cs transfer；
3. the charge of standard capacitance Cs transfer of the monitored capacitor Cx in capacitance type sensor into observation circuit reaches balance
After state, starts the AD conversion function of single-chip microcontroller (1) in observation circuit, measure described AD mouthfuls of voltage VAD, and standard capacitance Cs
The voltage Vcs=V at both endsAD, Vcs is substituted into following formula
The value of monitored capacitor Cx can be obtained.
2. a kind of method for monitoring capacitance type sensor capacitance variations, it is characterised in that the observation circuit used is mainly by having
Standard capacitance Cs known to the single-chip microcontroller (1) and capacity of AD/IO Multifunctional mouth is formed, one end of standard capacitance Cs known to capacity
It is connect with one AD/IO mouthfuls of the single-chip microcontroller (1), the other end of standard capacitance Cs known to capacity and the single-chip microcontroller (1)
An I/O port or another AD/IO mouthfuls connection；
When monitoring the capacitance variations of capacitance type sensor, by the first electrode (4-1) of capacitance type sensor (4) and monitoring electricity
The contact connection that road acceptance of the bid pseudo-capacitance Cs is connect with the AD/IO mouth of single-chip microcontroller (1), by the second electrode of capacitance type sensor (4)
(4-2) is connect with the contact for connecing power supply of single-chip microcontroller (1) in the observation circuit；
Monitor the operating procedure of capacitance type sensor capacitance variations are as follows:
1. setting delivery outlet for two ports that the single-chip microcontroller (1) in observation circuit is connected with the both ends standard capacitance Cs, and will
They are set to low level 0 simultaneously, which makes the charge zero in standard capacitance Cs, and make to be monitored electricity in capacitance type sensor
Holding the quantity of electric charge that Cx is injected is Q=Vcc × Cx；
2. the single-chip microcontroller (1) in observation circuit is connected with the first electrode (4-1) of standard capacitance Cs and capacitance type sensor (4)
AD/IO mouth be arranged to AD mouthfuls, while by single-chip microcontroller in observation circuit (1) connect with the standard capacitance Cs other end in output shape
The I/O port or AD/IO mouthful of state are set to high level Vcc, the charge which obtain monitored capacitor Cx in last action step
Standard capacitance Cs transfer of the Q into observation circuit；
3. when the charge of standard capacitance Cs transfer of the monitored capacitor Cx in capacitance type sensor into observation circuit reaches flat
After weighing apparatus state, starts the AD conversion function of single-chip microcontroller (1) in observation circuit, measure the voltage V of the port ADAD, and standard capacitance Cs
The voltage Vcs=Vcc-V at both endsAD, Vcs is substituted into following formula
The value of monitored capacitor Cx can be obtained.
3. a kind of method for monitoring capacitance type sensor capacitance variations, it is characterised in that the observation circuit used is mainly by having
Standard capacitance Cs known to the single-chip microcontroller (1) and capacity of AD/IO Multifunctional mouth is formed, one end of standard capacitance Cs known to capacity
It is connect with one AD/IO mouthfuls of the single-chip microcontroller (1), the other end of standard capacitance Cs known to capacity and the single-chip microcontroller (1)
An I/O port or another AD/IO mouthfuls connection；
When monitoring the capacitance variations of capacitance type sensor, by the first electrode (4-1) of capacitance type sensor (4) and monitoring electricity
The contact connection that road acceptance of the bid pseudo-capacitance Cs is connect with the AD/IO mouth of single-chip microcontroller (1), by the second electrode of capacitance type sensor (4)
(4-2) is connect with the I/O port that single-chip microcontroller (1) is not used by the observation circuit or AD/IO mouthfuls；
Monitor the operating procedure of capacitance type sensor capacitance variations are as follows:
1. I/O port or AD/IO that single-chip microcontroller in observation circuit (1) is connect with the second electrode (4-2) of capacitance type sensor (4)
Mouth is arranged to delivery outlet and is set to low level 0；
2. setting delivery outlet for two ports that the single-chip microcontroller (1) in observation circuit is connected with the both ends standard capacitance Cs, and will
They are set to high level Vcc simultaneously, which makes the charge zero in standard capacitance Cs, and make to be monitored in capacitance type sensor
The quantity of electric charge that capacitor Cx is injected is Q=VCC×Cx；
3. the single-chip microcontroller (1) in observation circuit is connect with the first electrode (4-1) of standard capacitance Cs and capacitance type sensor (4)
AD/IO mouth be arranged to AD mouthfuls, while by single-chip microcontroller (1) connect with the standard capacitance Cs other end in output state I/O port or
AD/IO mouthfuls are set to low level 0, and the charge Q which obtain monitored capacitor Cx in last action step is to observation circuit
In standard capacitance Cs transfer；
4. the charge of standard capacitance Cs transfer of the monitored capacitor Cx in capacitance type sensor into observation circuit reaches balance
After state, starts the AD conversion function of single-chip microcontroller (1) in observation circuit, measure described AD mouthfuls of voltage VAD, and standard capacitance Cs
The voltage Vcs=V at both endsAD, Vcs is substituted into following formula
The value of monitored capacitor Cx can be obtained；
Or the operating procedure of monitoring capacitance type sensor capacitance variations are as follows:
1. I/O port or AD/IO that single-chip microcontroller in observation circuit (1) is connect with the second electrode (4-2) of capacitance type sensor (4)
Mouth is arranged to delivery outlet and is set to high level Vcc；
2. setting delivery outlet for two ports that the single-chip microcontroller (1) in observation circuit is connected with the both ends standard capacitance Cs, and will
They are set to low level 0 simultaneously, which makes the charge zero in standard capacitance Cs, and make to be monitored electricity in capacitance type sensor
Holding the quantity of electric charge that Cx is injected is Q=Vcc × Cx；
3. the single-chip microcontroller (1) in observation circuit is connected with the first electrode (4-1) of standard capacitance Cs and capacitance type sensor (4)
AD/IO mouth be arranged to AD mouthfuls, while by single-chip microcontroller in observation circuit (1) connect with the standard capacitance Cs other end in output shape
The I/O port or AD/IO mouthful of state are set to high level Vcc, the charge which obtain monitored capacitor Cx in last action step
Standard capacitance Cs transfer of the Q into observation circuit；
4. when the charge of standard capacitance Cs transfer of the monitored capacitor Cx in capacitance type sensor into observation circuit reaches flat
After weighing apparatus state, starts the AD conversion function of single-chip microcontroller (1) in observation circuit, measure the voltage V of the port ADAD, and standard capacitance Cs
The voltage Vcs=Vcc-V at both endsAD, Vcs is substituted into following formula
The value of monitored capacitor Cx can be obtained.
4. according to claim 1 to the method for monitoring capacitance type sensor capacitance variations described in any claim in 3, feature
Be using observation circuit further include the first connector (2), first connector (2) pass through the first contained contact (2-
1) connection of Chip Microcomputer A/D/I/O port one end is connect with standard capacitance Cs known to capacity, by contained the second contact (2-2) with
The contact connection of single-chip microcontroller ground connection, or connect by contained the second contact (2-2) with the contact for connecing power supply of single-chip microcontroller, or
I/O port that person is not used by by contained the second contact (2-2) and single-chip microcontroller or AD/IO mouthfuls are connect；
When monitoring the capacitance variations of capacitance type sensor, by the first electrode (4-1) of capacitance type sensor and the first connector (2)
In the first contact (2-1) connection, the second electrode (4-2) of capacitance type sensor is connect with second in the first connector (2)
Point (2-2) connection.
5. monitoring the method for capacitance type sensor capacitance variations according to claim 4, it is characterised in that the monitoring electricity used
Road further includes the second connector (3), second connector (3) by contained the first contact (3-1), the second contact (3-2),
Third contact (3-3), the 4th contact (3-4), the 5th contact (3-5) send mouth with the power supply of single-chip microcontroller (1), communication respectively, lead to
It interrogates receiving port, reset mouth and the contact connection of ground connection.
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Cited By (1)
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| CN110749779A (en) * | 2019-12-05 | 2020-02-04 | 上海芯凌微电子有限公司 | Capacitance change detection method and circuit for capacitive sensor |
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