CN103475352B - The detection circuit of capacitance touch button - Google Patents
The detection circuit of capacitance touch button Download PDFInfo
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- CN103475352B CN103475352B CN201310404940.2A CN201310404940A CN103475352B CN 103475352 B CN103475352 B CN 103475352B CN 201310404940 A CN201310404940 A CN 201310404940A CN 103475352 B CN103475352 B CN 103475352B
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Abstract
The invention discloses a kind of detection circuit of capacitance touch button.Including one the detection module for being detected to button, and for receiving the processing module of detection module output signal；Detection module includes the first electric capacity for being used to sense human body touch, the second electric capacity for providing reference voltage, and anti-phase scaling circuit.Wherein, the positive pole of the first electric capacity is connected to the first input end of anti-phase scaling circuit, and the positive pole of the second electric capacity is connected to the second input of anti-phase scaling circuit；The voltage difference of first electric capacity and the second electric capacity is amplified by anti-phase scaling circuit, and exports a magnitude of voltage to processing module.Two magnitudes of voltage are carried out differential amplification by anti-phase scaling circuit.After differential amplification, the voltage variety of the first electric capacity and the second electric capacity caused by working environment is disturbed is counteracted, interference of the working environment to testing result is eliminated.So as to effectively reduce the probability of the erroneous judgement of detection circuit and flase drop.
Description
Technical field
The present invention relates to electric detective technology field, the detection circuit of more particularly to a kind of capacitance touch button.
Background technology
Touch is current most directly perceived, most convenient, best suits the input mode of human behavior custom, is mechanically pressed with traditional
Key is compared, and capacitance touch induced key sensor construction is simple, cost is low, without particular components, is schemed using only simple PCB
Shape just can realize button.The capacitance touch detection technique of main flow has charge transfer technology, RC oscillator techniques, testing impedance technology
Etc. a variety of.In actual applications, above-mentioned detection technique is stained and the environmental change institute such as electromagnetic interference to temperature, humidity, surface
Caused flase drop and probability of miscarriage of justice are high.
The content of the invention
It is a primary object of the present invention to provide a kind of detection circuit of capacitance touch button, it is intended to reduce temperature, humidity,
Surface stain and the environmental change such as electromagnetic interference caused by flase drop and erroneous judgement probability.
To achieve these goals, the present invention provides a kind of detection circuit of capacitance touch button, and the detection circuit includes
One detection module for being detected to button, and for receiving the processing module of detection module output signal；The detection
Module includes the first electric capacity for being used to sense human body touch, and the second electric capacity for providing reference voltage, and anti-phase ratio are put
Big circuit, wherein, the positive pole of first electric capacity is connected to the first input end of anti-phase scaling circuit, second electric capacity
Positive pole be connected to the second input of anti-phase scaling circuit；The anti-phase scaling circuit is by the first electric capacity and second
The voltage difference of electric capacity is compared and enlarged, and exports a magnitude of voltage to the processing module.
Preferably, the detection module also includes the first power supply circuit for being used to charge for first electric capacity, and is used for
The second power supply circuit charged for second electric capacity, wherein, the input and the second power supply circuit of first power supply circuit
The externally connected dc source of input, the output end of first power supply circuit is connected to the positive pole of the first electric capacity, described
The output end of second power supply circuit is connected to the positive pole of the second electric capacity.
Preferably, first power supply circuit includes the first current source, and the input of first current source and outside are straight
Power supply connection is flowed, output end is connected with the positive pole of the first electric capacity；Second power supply circuit includes the second current source, described second
The input of current source is connected with external dc power, and output end is connected with the positive pole of the second electric capacity.
Preferably, the detection module also includes charging control circuit, and the charging control circuit includes first switch electricity
Road, second switch circuit and the 3rd on-off circuit, wherein, the first switch circuit, second switch circuit and the 3rd open
Powered-down Lu Junyu external ac power sources connection；When external ac power source is low level, the second switch circuit is opened with the 3rd
Powered-down road disconnects, and the first switch circuit turn-on simultaneously makes first current source be turned on external dc power, and described first
Current source charges to the first electric capacity, and second current source charges to the second electric capacity；When external ac power source is high level, institute
State the disconnection of first switch circuit, second switch circuit and the 3rd the on-off circuit conducting, first electric capacity and the second electric capacity
Electric discharge.
Preferably, the detection module also include sampling hold circuit, the input of the sampling hold circuit with it is described
The output end connection of anti-phase scaling circuit, the output end of the sampling hold circuit is connected to the processing module；It is described
Sampling hold circuit is sampled and stored to the output signal of anti-phase scaling circuit, and is sent to the processing mould
Block.
Preferably, the sampling hold circuit includes the first transmission gate circuit and for being deposited to the magnitude of voltage sampled
3rd electric capacity of storage, first transmission gate circuit includes the first control end, the second control end, input and output end, its
In, the external ac power source is connected with first control end, the inverted device of external ac power source and the described second control
End processed connection, the input of first transmission gate circuit is connected with the output end of the anti-phase scaling circuit, and described the
The output end of one transmission gate circuit is connected with the input of the 3rd electric capacity and the processing module；The external ac power source
The first transmission gate circuit is controlled to turn on, the first transmission gate circuit is sampled to the voltage of the anti-phase scaling circuit output
And store to the 3rd electric capacity, the magnitude of voltage of the 3rd electric capacity storage is exported to the processing module.Preferably, the inspection
Survey the first amplifying circuit and the second amplifying circuit that module also includes being used to improve voltage driving capability；Wherein, described first put
The input of big circuit is connected with the positive pole of first electric capacity, output end and the first input of the anti-phase scaling circuit
End connection；The input of second amplifying circuit is connected with the positive pole of second electric capacity, output end and the anti-phase ratio
The second input connection of amplifying circuit.
Preferably, first amplifying circuit and the second amplifying circuit are buffer circuits, and the buffer circuits include
First p-type metal-oxide-semiconductor and the first N-type metal-oxide-semiconductor, wherein, the source electrode of the first p-type metal-oxide-semiconductor is connected with external dc power, described
The drain electrode of first p-type metal-oxide-semiconductor is connected with the drain electrode of the first N-type metal-oxide-semiconductor and as output end, the grid of the first p-type metal-oxide-semiconductor
It is connected to the grid of the first N-type metal-oxide-semiconductor and as input；The source ground of the first N-type metal-oxide-semiconductor.
Preferably, the anti-phase scaling circuit includes operational amplifier, first resistor, second resistance, 3rd resistor
And the 4th resistance, wherein, described first resistor one end is connected to the positive input terminal of operational amplifier, and the other end is used as anti-phase ratio
The first input end of example amplifying circuit；Described second resistance one end is connected to the negative input end of operational amplifier, other end conduct
Second input of anti-phase scaling circuit；The positive input terminal of the operational amplifier is grounded through 3rd resistor；Described 4th
Resistance one end is connected to the negative input end of operational amplifier, and the other end is connected to the output end of operational amplifier and as anti-phase ratio
The output end of example amplifying circuit.
The first electric capacity, the second electric capacity for reference and anti-phase ratio of the invention by being provided for sensing human body touch
Example amplifying circuit.Two electric capacity are placed in identical working environment, with the change of working environment, and two electric capacity produce identical voltage and become
Change amount.The magnitude of voltage of the magnitude of voltage of first electric capacity and the second electric capacity is exported to anti-phase scaling circuit.Anti-phase scaling electricity
Two voltage differences are amplified on road.After differential amplification, the first electric capacity and the second electric capacity are counteracted caused by working environment is disturbed
Voltage difference, eliminates interference of the working environment to testing result.So as to effectively reduce the probability of the erroneous judgement of detection circuit and flase drop.
Brief description of the drawings
Fig. 1 is the structural representation of the detection embodiment of circuit one of capacitance touch button of the present invention；
Fig. 2 is the first amplifying circuit and the structural representation of the embodiment of the second amplifying circuit one in Fig. 1；
Fig. 3 be Fig. 1 in the embodiment of anti-phase scaling circuit one structural representation.
The realization, functional characteristics and advantage of the object of the invention will be described further referring to the drawings in conjunction with the embodiments.
Embodiment
It should be appreciated that the specific embodiments described herein are merely illustrative of the present invention, it is not intended to limit the present invention.
The present invention provides the detection circuit of capacitance touch button.
Reference picture 1, Fig. 1 is the structural representation of the detection embodiment of circuit one of capacitance touch button of the present invention.This implementation
The detection circuit for the capacitance touch button that example is provided, including one be used for the detection module 1 that is detected to button, and for receiving
The processing module 2 of the output signal of detection module 1.Detection module 1 includes the first electric capacity C1 for being used to sense human body touch, for carrying
Second electric capacity C2 of supply reference voltage, and anti-phase scaling circuit 11.Wherein, the first electric capacity C1 positive pole is connected to anti-phase
The first input end of scaling circuit 11, the second electric capacity C2 positive pole is connected to the second input of anti-phase scaling circuit 11
End.The voltage difference of first electric capacity C1 voltage and the second electric capacity C2 is compared and enlarged anti-phase scaling circuit 11,
And a magnitude of voltage is exported to processing module 2.
In the present embodiment, when people touches capacitance touch button, the first electric capacity C1 capacitance becomes big.Specially first electricity
Hold the capacitance (5~10pF) that the capacitances of C1 in itself add body capacitance.This programme is provided with the second electric capacity C2, the second electric capacity simultaneously
C2 is as reference capacitance, and its capacitance does not touch capacitance touch button with people and changed.It should be noted that the first electric capacity C1 and
Two electric capacity C2 are in same working environment, and the first electric capacity C1 and the second electric capacity C2 capacitance are influenceed by working environment, such as
Temperature, humidity, stained or electromagnetic interference are likely to cause the capacitance of above-mentioned electric capacity to change.Preferably, the first electric capacity C1 with
Second electric capacity C2 capacitance parameter is equal, so as to be effectively guaranteed when being disturbed by identical working environment, the first electric capacity C1
It is equal with the voltage variety produced by the second electric capacity C2.In the present embodiment, by the first electric capacity C1 magnitude of voltage and the second electricity
The magnitude of voltage for holding C2 is exported to anti-phase scaling circuit 11.Anti-phase scaling circuit 11 obtains two magnitude of voltage differential amplifications
To testing result.Concrete principle is as follows：
When people touches capacitance touch button, the second electric capacity C2 capacitance is constant, and the first electric capacity C1 capacitance becomes big, so as to lead
Cause the first electric capacity C1 charging rate slack-off, its voltage variety in the unit interval is smaller.The electricity of first electric capacity C1 and second
The charging current for holding C2 is equal so that in the equal time, and the first electric capacity C1 voltage variety is less than the second electric capacity C2 electricity
Variable quantity is pressed, so that the first electric capacity C1 and the second electric capacity C2 difference become big.First electric capacity C1 and anti-phase scaling electricity
The first input end connection on road 11, the second electric capacity C2 is connected with the second input of anti-phase scaling circuit 11.Anti-phase ratio
The difference of two input voltages of amplifying circuit 11 pair carries out anti-phase amplification, output voltage values to processing module 2.2 pairs of processing module
The magnitude of voltage of input is judged and performs corresponding order.When the first electric capacity C1 and the second electric capacity C2 are done by working environment
When disturbing, the first electric capacity C1 and the second electric capacity C2 capacitance will be big with time-varying or diminished, i.e. the first electric capacity C1 is dry because of working environment
Increasedd or decreased voltage is disturbed with the second electric capacity C2 because working environment disturbs increasedd or decreased voltage equal all the time.It is anti-phase
Scaling circuit 11 cancels out each other magnitudes of voltage of the first electric capacity C1 and the second electric capacity C2 caused by working environment is disturbed (i.e.
Zero) difference is.Therefore, the interference of working environment will not produce influence to the magnitude of voltage that anti-phase scaling circuit 11 is exported.From
And eliminate interference of the working environment to capacitance touch button.
The present invention is by being provided for sensing the first electric capacity C1, the second electric capacity C2 for reference of human body touch and anti-
Phase Proportion amplifying circuit 11.Two electric capacity are placed in identical working environment, and with the change of working environment, two electric capacity produce identical
Voltage variety.First electric capacity C1 magnitude of voltage and the second electric capacity C2 magnitude of voltage are exported to anti-phase scaling circuit 11.Instead
Phase Proportion amplifying circuit 11 amplifies two voltage differences.After differential amplification, the first electric capacity C1 and the second electric capacity C2 are counteracted because of work
Make the voltage difference caused by environmental disturbances, eliminate interference of the working environment to testing result.So as to effectively reduce detection electricity
Judge the probability with flase drop by accident in road.
Further, detection module 1 also include be used for for the first electric capacity C1 charge the first power supply circuit 12, and for for
Second power supply circuit 13 of the second electric capacity C2 chargings.Wherein, the input of the first power supply circuit 12 and the second power supply circuit 13
The externally connected dc source VDD of input, the output end of the first power supply circuit 12 is connected to the first electric capacity C1 positive pole, second
The output end of power supply circuit 13 is connected to the second electric capacity C2 positive pole.
It should be noted that the first power supply circuit 12 provides constant electric current for the first electric capacity C1, and it is the first electric capacity C1
Power supply.Second power supply circuit 13 provides constant electric current for the second electric capacity C2, and is powered for the second electric capacity C2.Further illustrate,
First power supply circuit 12 and the second power supply circuit 13 could be arranged to various ways, as long as being embodied as the electricity of the first electric capacity C1 and second
Hold C2 and constant electric current is provided.It is exemplified below two embodiments.
First embodiment, the first power supply circuit 12 includes the first current source I1, the first current source I1 input and outside
Dc source VDD connections, the first current source I1 output end is connected with the first electric capacity C1 positive pole.External dc power VDD is
First current source I1 powers, and the first current source I1 will export constant electric current to the first electric capacity C1, is the first electric capacity C1 chargings.The
Two power supply circuits 13 include the second current source I2, and the second current source I2 input is connected with external dc power VDD, output end
It is connected with the second electric capacity C2 positive pole.External dc power VDD is that the second current source I2 powers, and the second current source I2 outputs are constant
Electric current to the second electric capacity C2, be the second electric capacity C2 charging.It should be noted that said external dc source VDD magnitude of voltage
Scope is 1.8~5V.
Second embodiment, the first power supply circuit 12 includes first resistor, one end and the external dc power VDD of first resistor
Connection, the other end is connected with the first electric capacity C1 positive pole.External dc power VDD is provided through first resistor for the first electric capacity C1
Constant electric current is charged.Second power supply circuit 13 includes second resistance, one end and the external dc power VDD of second resistance
Connection, the other end is connected with the second electric capacity C2 positive pole.External dc power VDD is provided through second resistance for the second electric capacity C2
Constant electric current is charged.It should be noted that to cause the charging current of two electric capacity equal, setting first resistor R1 resistance
Value is equal with second resistance R2 resistance.
Further, detection module 1 also includes charging control circuit 14, and charging control circuit 14 includes first switch circuit
141st, the on-off circuit 143 of second switch circuit 142 and the 3rd；The first switch circuit 141, second switch circuit 142 with
And the 3rd on-off circuit 143 be connected with external ac power source Vin.When external ac power source Vin is low level, second switch
Circuit 142 disconnects with the 3rd on-off circuit 143, and first switch circuit 141 turns on and makes the first current source I1 and external dc electricity
Source VDD is turned on, and the first current source I1 charges to the first electric capacity C1, and the second current source I2 charges to the second electric capacity C2.When outside friendship
When flowing power supply Vin for high level, first switch circuit 141 is disconnected, and second switch circuit 142 is turned on the 3rd on-off circuit 143,
First electric capacity C1 and the second electric capacity C2 discharges.
It should be noted that first switch circuit 141 disconnects when external ac power source Vin is high level, during low level
Conducting.Embodiment is depending on actual conditions, as long as can realize function above in the protection domain of this programme.Together
Reason, second switch circuit 142 and the 3rd on-off circuit 143 are also same.It is exemplified below two embodiments of charging control circuit.
First embodiment, first switch circuit 141 is the second p-type metal-oxide-semiconductor P2, and second switch circuit 142 is the second N-type
Metal-oxide-semiconductor N2 and the 3rd on-off circuit 143 are the 3rd N-type metal-oxide-semiconductor N3；Second p-type metal-oxide-semiconductor P2 drain electrode and external dc power
VDD connections, source electrode is connected with the first current source I1 input and the second current source I2 input, grid and the second N-type MOS
Pipe N2, the 3rd N-type metal-oxide-semiconductor N3 grid and external ac power source Vin connections；Second N-type metal-oxide-semiconductor N2 drain electrode is connected to first
Electric capacity C1 positive pole, source ground GND；3rd N-type metal-oxide-semiconductor N3 drain electrode is connected to the second electric capacity C2 positive pole, source ground
GND.When external ac power source Vin is low level, the second p-type metal-oxide-semiconductor P2 is turned on, the second N-type metal-oxide-semiconductor N2 and the 3rd N-type MOS
Pipe N3 disconnects, and the first current source I1 charges to the first electric capacity C1, and the second current source I2 charges to the second electric capacity C2.Work as external communication
When power supply Vin is high level, the second p-type metal-oxide-semiconductor P2 is disconnected, and the second N-type metal-oxide-semiconductor N2 and the 3rd N-type metal-oxide-semiconductor N3 are turned on, and first
Electric capacity C1 discharges over the ground, and the second electric capacity C2 discharges over the ground.Above circuit realiration is by external ac power source Vin to the first electric capacity
C1 and the second electric capacity C2 charge and discharges control.
Second embodiment, first switch circuit 141 is that the second transmission gate circuit, second switch circuit 142 are the 3rd transmission
Gate circuit and the 3rd on-off circuit 143 are the 4th transmission gate circuit.It should be noted that transmission gate circuit mentioned above
Include two control ends：First control end and the second control end.The first of external ac power source Vin and the second transmission gate circuit
Control end is connected, and the inverted device Inv of external ac power source Vin are connected with the second control end of the second transmission gate circuit.Second passes
The input of defeated gate circuit is connected with external dc power VDD, and output end is connected with the first current source I1.External ac power source
Vin is connected with the first control end of the 3rd transmission gate circuit, the inverted device Inv of external ac power source Vin and the 3rd transmission gate electricity
The second control end connection on road.The input of 3rd transmission gate circuit is connected to the first current source I1, output head grounding GND.Outside
Portion AC power Vin is connected with the first control end of the 4th transmission gate circuit.The inverted device Inv of external ac power source Vin and
The second control end connection of four transmission gate circuits.The input of 4th transmission gate circuit is connected to the second current source I2, output end
It is grounded GND.When external ac power source Vin is low level, the second transmission gate circuit conducting, the 3rd transmission gate circuit and the 4th is passed
Defeated gate turnoff.First current source I1 is connected with the second current source I2 with external dc power VDD, so that the first electricity
Stream source I1 charges to the first electric capacity C1, and the second current source I2 charges to the second electric capacity C2.When external ac power source Vin is high level
When, the second transmission gate circuit is disconnected, and the 3rd transmission gate circuit and the 4th transmission gate circuit are turned on, so that the first current source I1
GND is grounded with the second current source I2 and the first electric capacity C1 and the second electric capacity C2 is discharged.Above circuit realiration passes through outside
Controls of the AC power Vin to the first electric capacity C1 and the second electric capacity C2 charge and discharges.
Further, detection module 1 also includes sampling hold circuit 15, the input of sampling hold circuit 15 and anti-phase ratio
The output end connection of example amplifying circuit 11, the output end of sampling hold circuit 15 is connected to processing module 2；Sampling hold circuit 15
Output signal to anti-phase scaling circuit 11 is sampled and stored, and is sent to processing module 2.
In the present embodiment, the magnitude of voltage that sampling hold circuit 15 is exported to anti-phase scaling circuit 11 is sampled,
And further store, processing module 2 is then forwarded to, processing module 2 is further handled the magnitude of voltage received again.
Specifically, sampling hold circuit 15 includes the first transmission gate circuit T1 and for being deposited to the magnitude of voltage sampled
3rd electric capacity C3 of storage, the first transmission gate circuit T1 include the first control end, the second control end, input and output end.Its
In, external ac power source Vin is connected with the first control end, and the inverted device Inv of external ac power source Vin and the second control end connect
Connect.First transmission gate circuit T1 input is connected with the output end of anti-phase scaling circuit, the first transmission gate circuit T1's
Output end is connected with the 3rd electric capacity C3 and the processing module input；External ac power source Vin controls the first transmission gate electricity
Road T1 is turned on, and the voltage that the first transmission gate circuit T1 is exported to anti-phase scaling circuit is sampled and stored to the 3rd electric capacity
The magnitude of voltage of C3, the 3rd electric capacity C3 storage is exported to processing module.
In the present embodiment, when external ac power source Vin is low level, the first transmission gate circuit T1 conductings, first passes
Defeated gate circuit T1 input terminal voltage will be equal to output end voltage.First transmission gate circuit T1 input with it is anti-phase scaling
The output end connection of circuit 11, therefore the voltage of the first transmission gate circuit T1 output ends and the anti-phase output end of scaling circuit 11
Voltage it is equal.It is achieved thereby that signal acquisitions of the first transmission gate circuit T1 to anti-phase scaling circuit 11.3rd electric capacity
C3 is connected with the first transmission gate circuit T1 output end, and when the first transmission gate circuit T1 is turned on, the 3rd electric capacity C3 will be to first
Transmission gate circuit T1 output voltages are stored.The magnitude of voltage of 3rd electric capacity C3 storages is sent to processing module 2, processing module 2
Analyzed and processed again, perform corresponding order.
Further, the first amplifying circuit 16 and second that detection module 1 also includes being used to improve voltage driving capability is put
Big circuit 17.Wherein, the input of the first amplifying circuit 16 is connected with the first electric capacity C1 positive pole, and output end and anti-phase ratio are put
The first input end connection of big circuit 11.First 16 couple of first electric capacity C1 of amplifying circuit magnitude of voltage is amplified, and will amplification
Magnitude of voltage afterwards is exported to anti-phase scaling circuit 11, so as to improve input to the driving energy of anti-phase scaling circuit 11
Power.The input of second amplifying circuit 17 is connected with the second electric capacity C2 positive pole, output end and anti-phase scaling circuit 11
Second input is connected.Second 17 couple of second electric capacity C2 of amplifying circuit magnitude of voltage is amplified, and by the magnitude of voltage after amplification
Output is to anti-phase scaling circuit 11, so as to improve input to the driving force of anti-phase scaling circuit 11.
With reference to reference picture 2, Fig. 2 is the first amplifying circuit in Fig. 1 and the structural representation of the embodiment of the second amplifying circuit one
Figure.Based on above-described embodiment, specifically, the first amplifying circuit 16 and the second amplifying circuit 17 can have numerous embodiments, only
Realize and the magnitude of voltage inputted to the anti-phase first input end of scaling circuit 11 and the second input is amplified.
In the present embodiment, the first amplifying circuit 16 and the second amplifying circuit 17 are buffer circuits, and buffer circuits include the first p-type
Metal-oxide-semiconductor P1 and the first N-type metal-oxide-semiconductor N1；First p-type metal-oxide-semiconductor P1 source electrode is connected with external dc power VDD, the first p-type MOS
Pipe P1 drain electrode is connected with the first N-type metal-oxide-semiconductor N1 drain electrode and as output end vo ut, and the first p-type metal-oxide-semiconductor P1 grid is connected
To the first N-type metal-oxide-semiconductor N1 grid and be used as input Vin；First N-type metal-oxide-semiconductor N1 source ground GND.
With reference to reference picture 3, Fig. 3 is the structural representation of the embodiment of anti-phase scaling circuit one in Fig. 1.Specifically,
Anti-phase scaling circuit 11 includes operational amplifier A MP, 3rd resistor R3, the 4th resistance R4, the 5th resistance R5 and the 6th
Resistance R6,3rd resistor R3 one end is connected to operational amplifier A MP positive input terminal, and the other end is used as anti-phase scaling electricity
The first input end on road 11；4th resistance R4 one end is connected to operational amplifier A MP negative input end, and the other end is used as anti-phase ratio
Second input of example amplifying circuit 11；Operational amplifier A MP positive input terminal is grounded GND through the 5th resistance R5；6th resistance
R6 one end is connected to operational amplifier A MP negative input end, and the other end is connected to operational amplifier A MP output end and as anti-
The output end of Phase Proportion amplifying circuit 11.
The preferred embodiments of the present invention are the foregoing is only, are not intended to limit the scope of the invention, it is every to utilize
The equivalent structure transformation that description of the invention and accompanying drawing content are made, or directly or indirectly it is used in other related technology necks
Domain, is included within the scope of the present invention.
Claims (7)
1. a kind of detection circuit of capacitance touch button, including one is used for the detection module that is detected to button, and for connecing
Receive the processing module of detection module output signal；Characterized in that, the detection module includes being used to sense the of human body touch
One electric capacity, the second electric capacity for providing reference voltage, and anti-phase scaling circuit, wherein the first electric capacity and the second electric capacity
Capacitor's capacity it is equal；The detection module also includes the first amplifying circuit and the second amplification for being used to improve voltage driving capability
Circuit；The detection module also includes sampling hold circuit,
Wherein, the input of first amplifying circuit is connected with the positive pole of first electric capacity, output end and the anti-phase ratio
The first input end connection of example amplifying circuit；The input of second amplifying circuit is connected with the positive pole of second electric capacity,
Output end is connected with the second input of the anti-phase scaling circuit；
The voltage difference of first electric capacity and the second electric capacity is compared and enlarged the anti-phase scaling circuit, and exports an electricity
Pressure is worth to the sampling hold circuit；
The input of the sampling hold circuit is connected with the output end of the anti-phase scaling circuit, and the sampling keeps electricity
The output end on road is connected to the processing module；The sampling hold circuit is carried out to the output signal of anti-phase scaling circuit
Sample and stored, and send to the processing module.
2. circuit is detected as claimed in claim 1, it is characterised in that the detection module also includes being used for for the described first electricity
First power supply circuit of capacity charge, and the second power supply circuit for being charged for second electric capacity, wherein, first power supply
The externally connected dc source of input of the input of circuit and the second power supply circuit, the output end of first power supply circuit
The positive pole of the first electric capacity is connected to, the output end of second power supply circuit is connected to the positive pole of the second electric capacity.
3. circuit is detected as claimed in claim 2, it is characterised in that first power supply circuit includes the first current source, institute
The input for stating the first current source is connected with external dc power, and output end is connected with the positive pole of the first electric capacity；Described second supplies
Circuit includes the second current source, and the input of second current source is connected with external dc power, output end and the second electricity
The positive pole connection of appearance.
4. circuit is detected as claimed in claim 3, it is characterised in that the detection module also includes charging control circuit, institute
Stating charging control circuit includes first switch circuit, second switch circuit and the 3rd on-off circuit, wherein, the first switch
Circuit, second switch circuit and the 3rd on-off circuit are connected with external ac power source；When external ac power source is low level
When, the second switch circuit and the 3rd on-off circuit disconnect, and the first switch circuit turn-on simultaneously makes first current source
Turned on external dc power, first current source charges to the first electric capacity, and second current source charges to the second electric capacity；
When external ac power source is high level, the first switch circuit disconnects, the second switch circuit and the 3rd on-off circuit
Conducting, the first electric capacity and the second electric capacity electric discharge.
5. circuit is detected as claimed in claim 1, it is characterised in that the sampling hold circuit includes the first transmission gate circuit
With the 3rd electric capacity for being stored to the magnitude of voltage sampled, first transmission gate circuit includes the first control end, the
Two control ends, input and output end, wherein, external ac power source is connected with first control end, the external communication
The inverted device of power supply is connected with second control end, the input of first transmission gate circuit with it is described anti-phase scaling
The output end connection of circuit, the input of the output end and the 3rd electric capacity and the processing module of first transmission gate circuit
End connection；The external ac power source controls the conducting of the first transmission gate circuit, and the first transmission gate circuit is put to the anti-phase ratio
The voltage of big circuit output is sampled and stored to the 3rd electric capacity, and the magnitude of voltage of the 3rd electric capacity storage is exported to institute
State processing module.
6. circuit is detected as claimed in claim 1, it is characterised in that first amplifying circuit and the second amplifying circuit are slow
Device circuit is rushed, the buffer circuits include the first p-type metal-oxide-semiconductor and the first N-type metal-oxide-semiconductor, wherein, the first p-type metal-oxide-semiconductor
Source electrode is connected with external dc power, and the drain electrode of the first p-type metal-oxide-semiconductor is connected and made with the drain electrode of the first N-type metal-oxide-semiconductor
For output end, the grid of the first p-type metal-oxide-semiconductor is connected to the grid of the first N-type metal-oxide-semiconductor and as input；First N-type
The source ground of metal-oxide-semiconductor.
7. circuit is detected as claimed in claim 1, it is characterised in that the anti-phase scaling circuit includes operation amplifier
Device, first resistor, second resistance, 3rd resistor and the 4th resistance, wherein, described first resistor one end is connected to operation amplifier
The positive input terminal of device, the other end as anti-phase scaling circuit first input end；Described second resistance one end is connected to fortune
Calculate amplifier negative input end, the other end as anti-phase scaling circuit the second input；The operational amplifier is just
Input is grounded through 3rd resistor；Described 4th resistance one end is connected to the negative input end of operational amplifier, and the other end is connected to
The output end of operational amplifier is simultaneously used as the output end of anti-phase scaling circuit.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
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| US10126893B2 (en) | 2014-03-04 | 2018-11-13 | Nokia Technologies Oy | Method and apparatus for capacitive sensing |
| WO2019144305A1 (en) * | 2018-01-24 | 2019-08-01 | 深圳市汇顶科技股份有限公司 | Capacitance detection circuit, touch detection apparatus and terminal device |
| CN111492580A (en) * | 2018-04-20 | 2020-08-04 | 华为技术有限公司 | Overvoltage protection circuit of MOS (metal oxide semiconductor) tube in wireless receiving circuit |
| CN109557143B (en) * | 2018-10-30 | 2020-05-05 | 电子科技大学 | Capacitive humidity sensor interface circuit |
| KR102504896B1 (en) * | 2019-05-22 | 2023-02-28 | 알프스 알파인 가부시키가이샤 | capacitance detection sensor |
| CN110196387B (en) * | 2019-06-04 | 2021-09-03 | 苏州蓝石新动力有限公司 | Damp-proof key identification method and device, electronic equipment and readable storage medium |
| CN211348433U (en) * | 2019-07-16 | 2020-08-25 | 深圳市汇顶科技股份有限公司 | Capacitance detection device and electronic equipment |
| CN111289805A (en) * | 2020-03-23 | 2020-06-16 | 深圳市汇顶科技股份有限公司 | Measuring circuit |
| WO2022155874A1 (en) * | 2021-01-22 | 2022-07-28 | 深圳市汇顶科技股份有限公司 | Detection circuit, chip, and related electronic apparatus |
| CN112415604B (en) * | 2021-01-22 | 2021-06-18 | 深圳市汇顶科技股份有限公司 | Detection circuit, chip and related electronic device |
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