CN103475352A - Detection circuit of capacitor touch key - Google Patents
Detection circuit of capacitor touch key Download PDFInfo
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- CN103475352A CN103475352A CN2013104049402A CN201310404940A CN103475352A CN 103475352 A CN103475352 A CN 103475352A CN 2013104049402 A CN2013104049402 A CN 2013104049402A CN 201310404940 A CN201310404940 A CN 201310404940A CN 103475352 A CN103475352 A CN 103475352A
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Abstract
The invention discloses a detection circuit of a capacitor touch key. The detection circuit of the capacitor touch key comprises a detection module used for detecting the key and a processing module used for receiving signals output through the detection module. The detection module comprises a first capacitor used for inducting human body touch, a second capacitor used for providing reference voltage and an invert proportional amplification circuit. A positive pole of the first capacitor is connected to a first input end of the invert proportional amplification circuit and a positive pole of the second capacitor is connected to a second input end of the invert proportional amplification circuit. The voltage difference value of the first capacitor and the second capacitor is amplified through the invert proportional amplification circuit and a voltage value is output to the processing module. Differential amplification is conducted on the two voltage values through the invert proportional amplification circuit. After differential amplification is conducted, the voltage change amount caused by work environment interference of the first capacitor and the second capacitor is counteracted and the interference in a detection result by the work environment is eliminated. Therefore, the probability of false judgment and false detection of the detection circuit is effectively reduced.
Description
Technical field
The present invention relates to the electric detective technology field, particularly a kind of testing circuit of capacitance touch button.
Background technology
Touch be at present the most directly perceived, most convenient, meet the input mode of human behavior custom most, with traditional mechanical key, compare, capacitance touch induced key sensor construction is simple, cost is low, without particular components, only uses simple PCB figure just can realize button.The capacitance touch detection technique of main flow has charge transfer technology, RC oscillator technology, testing impedance technology etc. multiple.In actual applications, above-mentioned detection technique temperature, humidity, surface are stained and the caused flase drop of environmental change such as electromagnetic interference and probability of miscarriage of justice high.
Summary of the invention
Main purpose of the present invention is to provide a kind of testing circuit of capacitance touch button, is intended to reduce temperature, humidity, stain on surface and the probability of the caused flase drop of environmental change such as electromagnetic interference and erroneous judgement.
To achieve these goals, the invention provides a kind of testing circuit of capacitance touch button, this testing circuit comprises a detection module for button is detected, and for receiving the processing module of detection module output signal; Described detection module comprises for responding to the first electric capacity of human body touch, for the second electric capacity of reference voltage is provided, and anti-phase ratio amplifying circuit, wherein, the positive pole of described the first electric capacity is connected to the first input end of anti-phase ratio amplifying circuit, and the positive pole of described the second electric capacity is connected to the second input of anti-phase ratio amplifying circuit; Described anti-phase ratio amplifying circuit compares and enlarges the voltage difference of the first electric capacity and the second electric capacity, and exports a magnitude of voltage to described processing module.
Preferably, described detection module also comprises the first power supply circuits that are used to described the first capacitor charging, with the second power supply circuits that are used to described the second capacitor charging, wherein, the input of the input of described the first power supply circuits and the second power supply circuits is connected to external dc power, the output of described the first power supply circuits is connected to the positive pole of the first electric capacity, and the output of described the second power supply circuits is connected to the positive pole of the second electric capacity.
Preferably, described the first power supply circuits comprise the first current source, and the input of described the first current source is connected with external dc power, and output is connected with the positive pole of the first electric capacity; Described the second power supply circuits comprise the second current source, and the input of described the second current source is connected with external dc power, and output is connected with the positive pole of the second electric capacity.
Preferably, described detection module also comprises charging control circuit, described charging control circuit comprises the first switching circuit, second switch circuit and the 3rd switching circuit, and wherein, described the first switching circuit, second switch circuit and the 3rd switching circuit all are connected with external ac power source; When external ac power source is low level, described second switch circuit and the 3rd switching circuit disconnect, described the first switching circuit conducting also makes described the first current source and external dc power conducting, and described the first power supply is to the first capacitor charging, and described second source is to the second capacitor charging; When external ac power source is high level, described the first switching circuit disconnects, described second switch circuit and the 3rd switching circuit conducting, described the first electric capacity and the second capacitor discharge.
Preferably, described detection module also comprises sampling hold circuit, and the input of described sampling hold circuit is connected with the output of described anti-phase ratio amplifying circuit, and the output of described sampling hold circuit is connected to described processing module; Described sampling hold circuit is sampled and is stored the output signal of anti-phase ratio amplifying circuit, and is sent to described processing module.
Preferably, described sampling hold circuit comprises the first transmission gate circuit and the 3rd electric capacity of being stored for the magnitude of voltage to sampling, described the first transmission gate circuit comprises the first control end, the second control end, input and output, wherein, described external ac power source is connected with described the first control end, described external ac power source is connected with described the second control end through inverter, the input of described the first transmission gate circuit is connected with the output of described anti-phase ratio amplifying circuit, the output of described the first transmission gate circuit is connected with the input of described the 3rd electric capacity and described processing module, described external ac power source is controlled the first transmission gate circuit conducting, and the first transmission gate circuit is sampled and is stored to described the 3rd electric capacity the voltage of described anti-phase ratio amplifying circuit output, and the magnitude of voltage of described the 3rd capacitance stores exports described processing module to.Preferably, described detection module also comprises the first amplifying circuit and the second amplifying circuit for improving the voltage driving force; Wherein, the input of described the first amplifying circuit is connected with the positive pole of described the first electric capacity, and output is connected with the first input end of described anti-phase ratio amplifying circuit; The input of described the second amplifying circuit is connected with the positive pole of described the second electric capacity, and output is connected with the second input of described anti-phase ratio amplifying circuit.
Preferably, described the first amplifying circuit and the second amplifying circuit are buffer circuits, described buffer circuits comprises a P type metal-oxide-semiconductor and the first N-type metal-oxide-semiconductor, wherein, the source electrode of a described P type metal-oxide-semiconductor is connected with external dc power, the drain electrode of a described P type metal-oxide-semiconductor is connected with the drain electrode of described the first N-type metal-oxide-semiconductor and as output, and the grid of a P type metal-oxide-semiconductor is connected to the grid of the first N-type metal-oxide-semiconductor and as input; The source ground of described the first N-type metal-oxide-semiconductor.
Preferably, described anti-phase ratio amplifying circuit comprises operational amplifier, the first resistance, the second resistance, the 3rd resistance and the 4th resistance, wherein, described the first resistance one end is connected to the positive input terminal of operational amplifier, and the other end is as the first input end of anti-phase ratio amplifying circuit; Described the second resistance one end is connected to the negative input end of operational amplifier, and the other end is as the second input of anti-phase ratio amplifying circuit; The positive input terminal of described operational amplifier is through the 3rd grounding through resistance; Described the 4th resistance one end is connected to the negative input end of operational amplifier, and the other end is connected to the output of operational amplifier and as the output of anti-phase ratio amplifying circuit.
First electric capacity of the present invention by being provided for responding to human body touch, for the second electric capacity and the anti-phase ratio amplifying circuit of reference.Two electric capacity are placed in identical operational environment, and along with the variation of operational environment, two electric capacity produce identical voltage variety.The magnitude of voltage of the magnitude of voltage of the first electric capacity and the second electric capacity exports anti-phase ratio amplifying circuit to.Anti-phase ratio amplifying circuit amplifies two voltage differences.After differential amplification, offset the first electric capacity and the second electric capacity because operational environment disturbs caused voltage difference, got rid of the interference of operational environment to testing result.Thereby effectively reduce the probability of testing circuit erroneous judgement and flase drop.
The accompanying drawing explanation
The structural representation of testing circuit one embodiment that Fig. 1 is capacitance touch button of the present invention;
Fig. 2 is the first amplifying circuit in Fig. 1 and the structural representation of the second amplifying circuit one embodiment;
The structural representation that Fig. 3 is anti-phase ratio amplifying circuit one embodiment in Fig. 1.
The realization of the object of the invention, functional characteristics and advantage, in connection with embodiment, are described further with reference to accompanying drawing.
Embodiment
Should be appreciated that specific embodiment described herein, only in order to explain the present invention, is not intended to limit the present invention.
The invention provides the testing circuit of capacitance touch button.
With reference to Fig. 1, the structural representation of testing circuit one embodiment that Fig. 1 is capacitance touch button of the present invention.The testing circuit of the capacitance touch button that the present embodiment provides, comprise a detection module 1 for button is detected, and for receiving the processing module 2 of detection module 1 output signal.Detection module 1 comprises for responding to the first capacitor C 1 of human body touch, for the second capacitor C 2 of reference voltage is provided, and anti-phase ratio amplifying circuit 11.Wherein, the positive pole of the first capacitor C 1 is connected to the first input end of anti-phase ratio amplifying circuit 11, and the positive pole of the second capacitor C 2 is connected to the second input of anti-phase ratio amplifying circuit 11.Anti-phase ratio amplifying circuit 11 by the voltage of the first capacitor C 1 and the second capacitor C 2 voltage difference compare and enlarge, and export a magnitude of voltage to processing module 2.
In the present embodiment, when the people touches capacitance touch button, it is large that the appearance value of the first capacitor C 1 becomes.Be specially the appearance value (5～10pF) that the first capacitor C 1 appearance value own adds body capacitance.This programme is provided with the second capacitor C 2, the second capacitor C 2 conducts with reference to electric capacity simultaneously, and its appearance value does not touch capacitance touch button with the people and changes.Should be noted that, the first capacitor C 1 and the second capacitor C 2 are in same operational environment, and the appearance value of the first capacitor C 1 and the second capacitor C 2 all is subject to the impact of operational environment, as temperature, humidity, stain or electromagnetic interference all likely causes the appearance value of above-mentioned electric capacity to change.Preferably, the first capacitor C 1 equates with the capacitance parameter of the second capacitor C 2, thereby, while effectively having guaranteed to be subject to identical operational environment interference, the voltage variety that the first capacitor C 1 and the second capacitor C 2 produce equates.In the present embodiment, export the magnitude of voltage of the magnitude of voltage of the first capacitor C 1 and the second capacitor C 2 to anti-phase ratio amplifying circuit 11.Anti-phase ratio amplifying circuit 11, by two magnitude of voltage differential amplifications, obtains testing result.Concrete principle is as follows:
When the people touches capacitance touch button, the appearance of the second capacitor C 2 value is constant, and it is large that the appearance value of the first capacitor C 1 becomes, thereby cause the charging rate of the first capacitor C 1 slack-off, and its voltage variety in the unit interval is less.The first capacitor C 1 equates with the charging current of the second capacitor C 2, makes in the equal time, and the voltage variety of the first capacitor C 1 is less than the voltage variety of the second capacitor C 2, thereby makes the difference of the first capacitor C 1 and the second capacitor C 2 become large.The first capacitor C 1 is connected with the first input end of anti-phase ratio amplifying circuit 11, and the second capacitor C 2 is connected with the second input of anti-phase ratio amplifying circuit 11.The difference of 11 pairs of two input voltages of anti-phase ratio amplifying circuit is carried out anti-phase amplification, and output voltage values is to processing module 2.The magnitude of voltage of 2 pairs of inputs of processing module is judged and carries out accordingly and order.When the first capacitor C 1 and the second capacitor C 2 are subject to the interference of operational environment, the appearance value of the first capacitor C 1 and the second capacitor C 2 will become large simultaneously or diminish, and the first capacitor C 1 equates because of the voltage that operational environment disturbs institute to increase or reduce with the second capacitor C 2 all the time because of the voltage that operational environment disturbs institute to increase or reduce.Anti-phase ratio amplifying circuit 11 by the first capacitor C 1 and the second capacitor C 2 because operational environment disturbs caused magnitude of voltage cancel out each other (being that difference is zero).Therefore, the interference of operational environment can not exert an influence to the magnitude of voltage of anti-phase ratio amplifying circuit 11 outputs.Thereby got rid of the interference of operational environment to capacitance touch button.
Further, detection module 1 also comprises the first power supply circuits 12 that are used to the first capacitor C 1 charging, and is used to the second power supply circuits 13 of the second capacitor C 2 chargings.Wherein, the input of the input of the first power supply circuits 12 and the second power supply circuits 13 is connected to external dc power VDD, the output of the first power supply circuits 12 is connected to the positive pole of the first capacitor C 1, and the output of the second power supply circuits 13 is connected to the positive pole of the second capacitor C 2.
It should be noted that the first power supply circuits 12 provide constant electric current for the first capacitor C 1, and be the first capacitor C 1 power supply.The second power supply circuits 13 provide constant electric current for the second capacitor C 2, and are the second capacitor C 2 power supplies.Further illustrate, the first power supply circuits 12 and the second power supply circuits 13 can be set to various ways, as long as be embodied as the first capacitor C 1 and the second capacitor C 2 provides constant electric current.Below row for two example two.
The first embodiment, the first power supply circuits 12 comprise the first current source I1, and the input of the first current source I1 is connected with external dc power VDD, and the output of the first current source I1 is connected with the positive pole of the first capacitor C 1.External dc power VDD is the first current source I1 power supply, and the first current source I1 will export constant electric current to the first capacitor C 1, is the first capacitor C 1 charging.The second power supply circuits 13 comprise the second current source I2, and the input of the second current source I2 is connected with external dc power VDD, and output is connected with the positive pole of the second capacitor C 2.External dc power VDD is the second current source I2 power supply, and the second current source I2 exports constant electric current to the second capacitor C 2, is the second capacitor C 2 chargings.The range of voltage values that it should be noted that said external DC power supply VDD is 1.8～5V.
The second embodiment, the first power supply circuits 12 comprise the first resistance, and an end of the first resistance is connected with external dc power VDD, and the other end is connected with the positive pole of the first capacitor C 1.External dc power VDD, through the first resistance, is charged for the first capacitor C 1 provides constant electric current.The second power supply circuits 13 comprise the second resistance, and an end of the second resistance is connected with external dc power VDD, and the other end is connected with the positive pole of the second capacitor C 2.External dc power VDD, through the second resistance, is charged for the second capacitor C 2 provides constant electric current.It should be noted that the charging current for making two electric capacity equates, the resistance that the first resistance R 1 is set equates with the resistance of the second resistance R 2.
Further, detection module 1 also comprises charging control circuit 14, and charging control circuit 14 comprises the first switching circuit 141, second switch circuit 142 and the 3rd switching circuit 143; Described the first switching circuit 141, second switch circuit 142 and the 3rd switching circuit 143 all are connected with external ac power source Vin.When external ac power source Vin is low level, second switch circuit 142 and the 3rd switching circuit 143 disconnect, the first switching circuit 141 conductings also make the first current source I1 and external dc power VDD conducting, and the first power supply I1 is to the first capacitor C 1 charging, and second source I2 is to the second capacitor C 2 chargings.When external ac power source Vin is high level, the first switching circuit 141 disconnects, second switch circuit 142 and the 3rd switching circuit 143 conductings, the first capacitor C 1 and the second capacitor C 2 electric discharges.
It should be noted that the first switching circuit 141 disconnects when externally AC power Vin is high level, conducting during low level.Embodiment is depending on actual conditions, as long as can realize that above function is all in the protection range of this programme.In like manner, second switch circuit 142 and the 3rd switching circuit 143 are also same.Below enumerate two embodiment of charging control circuit.
The first embodiment, the first switching circuit 141 is the 2nd P type metal-oxide-semiconductor P2, second switch circuit 142 is that the second N-type metal-oxide-semiconductor N2 and the 3rd switching circuit 143 are the 3rd N-type metal-oxide-semiconductor N3; The drain electrode of the 2nd P type metal-oxide-semiconductor P2 is connected with external dc power VDD, source electrode is connected with the input of the second current source I2 with the input of the first current source I1, and grid is connected with external ac power source Vin with the grid of the second N-type metal-oxide-semiconductor N2, the 3rd N-type metal-oxide-semiconductor N3; The drain electrode of the second N-type metal-oxide-semiconductor N2 is connected to the positive pole of the first capacitor C 1, source ground GND; The drain electrode of the 3rd N-type metal-oxide-semiconductor N3 is connected to the positive pole of the second capacitor C 2, source ground GND.When external ac power source Vin is low level, the 2nd P type metal-oxide-semiconductor P2 conducting, the second N-type metal-oxide-semiconductor N2 and the 3rd N-type metal-oxide-semiconductor N3 disconnect, and the first current source I1 is to the first capacitor C 1 charging, and the second current source I2 is to the second capacitor C 2 chargings.When external ac power source Vin is high level, the 2nd P type metal-oxide-semiconductor P2 disconnects, the second N-type metal-oxide-semiconductor N2 and the 3rd N-type metal-oxide-semiconductor N3 conducting, and the first capacitor C 1 is discharged over the ground, and the second capacitor C 2 is discharged over the ground.Above circuit has been realized the control to the first capacitor C 1 and the second capacitor C 2 charge and discharges by external ac power source Vin.
The second embodiment, the first switching circuit 141 is that the second transmission gate circuit, second switch circuit 142 are that the 3rd transmission gate circuit and the 3rd switching circuit 143 are the 4th transmission gate circuit.It should be noted that transmission gate circuit mentioned above includes two control ends: the first control end and the second control end.External ac power source Vin is connected with the first control end of the second transmission gate circuit, and external ac power source Vin is connected with the second control end of the second transmission gate circuit through inverter Inv.The input of the second transmission gate circuit is connected with external dc power VDD, and output 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, and external ac power source Vin is connected with the second control end of the 3rd transmission gate circuit through inverter Inv.The input of the 3rd transmission gate circuit is connected to the first current source I1, output head grounding GND.External ac power source Vin is connected with the first control end of the 4th transmission gate circuit.External ac power source Vin is connected with the second control end of the 4th transmission gate circuit through inverter Inv.The input of the 4th transmission gate circuit is connected to the second current source I2, output head grounding GND.When external ac power source Vin is low level, the second transmission gate circuit conducting, the 3rd transmission gate circuit and the 4th transmission gate circuit disconnect.The first current source I1 all is connected with external dc power VDD with the second current source I2, thereby makes the first current source I1 to the first capacitor C 1 charging, and the second current source I2 is to the second capacitor C 2 chargings.When external ac power source Vin is high level, the second transmission gate circuit disconnects, the 3rd transmission gate circuit and the 4th transmission gate circuit conducting, thus make the first current source I1 and the second current source I2 ground connection GND and make the first capacitor C 1 and the second capacitor C 2 electric discharges.Above circuit has been realized the control to the first capacitor C 1 and the second capacitor C 2 charge and discharges by external ac power source Vin.
Further, detection module 1 also comprises sampling hold circuit 15, and the input of sampling hold circuit 15 is connected with the output of anti-phase ratio amplifying circuit 11, and the output of sampling hold circuit 15 is connected to processing module 2; The output signal of 15 pairs of anti-phase ratio amplifying circuits 11 of sampling hold circuit is sampled and is stored, and is sent to processing module 2.
In the present embodiment, the magnitude of voltage of 15 pairs of anti-phase ratio amplifying circuit 11 outputs of sampling hold circuit is sampled, and further storage, then is sent to processing module 2, and processing module 2 is further processed the magnitude of voltage received again.
Particularly, sampling hold circuit 15 comprises that the first transmission gate circuit T1 and the 3rd capacitor C 3, the first transmission gate circuit T1 that stored for the magnitude of voltage to sampling comprise the first control end, the second control end, input and output.Wherein, external ac power source Vin is connected with the first control end, and external ac power source Vin is connected with the second control end through inverter Inv.The input of the first transmission gate circuit T1 is connected with the output of anti-phase ratio amplifying circuit, and the output of the first transmission gate circuit T1 is connected with the input of the 3rd capacitor C 3 and described processing module; External ac power source Vin controls the first transmission gate circuit T1 conducting, and the first transmission gate circuit T1 is sampled to the voltage of anti-phase ratio amplifying circuit output and the magnitude of voltage that is stored to the 3rd capacitor C 3, the three capacitor C 3 storages exports processing module to.
In the present embodiment, when external ac power source Vin is low level, the first transmission gate circuit T1 conducting, the input terminal voltage of the first transmission gate circuit T1 will equal output end voltage.The input of the first transmission gate circuit T1 is connected with the output of anti-phase ratio amplifying circuit 11, and therefore the voltage of the first transmission gate circuit T1 output equates with the voltage of anti-phase ratio amplifying circuit 11 outputs.Thereby realized the signals collecting of the first transmission gate circuit T1 to anti-phase ratio amplifying circuit 11.The 3rd capacitor C 3 is connected with the output of the first transmission gate circuit T1, and when the first transmission gate circuit T1 conducting, the 3rd capacitor C 3 will be stored the first transmission gate circuit T1 output voltage.The magnitude of voltage of the 3rd capacitor C 3 storages is sent to processing module 2, and processing module 2 is carried out analyzing and processing again, carries out order accordingly.
Further, detection module 1 also comprises the first amplifying circuit 16 and the second amplifying circuit 17 for improving the voltage driving force.Wherein, the input of the first amplifying circuit 16 is connected with the positive pole of the first capacitor C 1, and output is connected with the first input end of anti-phase ratio amplifying circuit 11.The magnitude of voltage of first 16 pairs of amplifying circuits the first capacitor C 1 is amplified, and exports the magnitude of voltage after amplifying to anti-phase ratio amplifying circuit 11, thereby has improved the driving force that inputs to anti-phase ratio amplifying circuit 11.The input of the second amplifying circuit 17 is connected with the positive pole of the second capacitor C 2, and output is connected with the second input of anti-phase ratio amplifying circuit 11.The magnitude of voltage of second 17 pairs of amplifying circuits the second capacitor C 2 is amplified, and exports the magnitude of voltage after amplifying to anti-phase ratio amplifying circuit 11, thereby has improved the driving force that inputs to anti-phase ratio amplifying circuit 11.
In conjunction with reference to Fig. 2, Fig. 2 is the first amplifying circuit in Fig. 1 and the structural representation of the second amplifying circuit one embodiment.Based on above-described embodiment, particularly, the first amplifying circuit 16 and the second amplifying circuit 17 can have numerous embodiments, as long as realize, the magnitude of voltage that inputs to anti-phase ratio amplifying circuit 11 first input ends and the second input are amplified.In the present embodiment, the first amplifying circuit 16 and the second amplifying circuit 17 are buffer circuits, and buffer circuits comprises a P type metal-oxide-semiconductor P1 and the first N-type metal-oxide-semiconductor N1; The source electrode of the one P type metal-oxide-semiconductor P1 is connected with external dc power VDD, the drain electrode of the one P type metal-oxide-semiconductor P1 is connected with the drain electrode of the first N-type metal-oxide-semiconductor N1 and as output end vo ut, and the grid of a P type metal-oxide-semiconductor P1 is connected to the grid of the first N-type metal-oxide-semiconductor N1 and as input Vin; The source ground GND of the first N-type metal-oxide-semiconductor N1.
In conjunction with reference to Fig. 3, the structural representation that Fig. 3 is anti-phase ratio amplifying circuit one embodiment in Fig. 1.Particularly, anti-phase ratio amplifying circuit 11 comprises operational amplifier A MP, the 3rd resistance R 3, the 4th resistance R 4, the 5th resistance R 5 and the 6th resistance R 6, one end of the 3rd resistance R 3 is connected to the positive input terminal of operational amplifier A MP, and the other end is as the first input end of anti-phase ratio amplifying circuit 11; The 4th resistance R 4 one ends are connected to the negative input end of operational amplifier A MP, and the other end is as the second input of anti-phase ratio amplifying circuit 11; The positive input terminal of operational amplifier A MP is through the 5th resistance R 5 ground connection GND; The 6th resistance R 6 one ends are connected to the negative input end of operational amplifier A MP, and the other end is connected to the output of operational amplifier A MP and as the output of anti-phase ratio amplifying circuit 11.
The foregoing is only the preferred embodiments of the present invention; not thereby limit the scope of the claims of the present invention; every equivalent structure transformation that utilizes specification of the present invention and accompanying drawing content to do; or directly or indirectly be used in other relevant technical fields, all in like manner be included in scope of patent protection of the present invention.
Claims (9)
1. the testing circuit of a capacitance touch button, comprise a detection module for button is detected, and for receiving the processing module of detection module output signal; It is characterized in that, described detection module comprises for responding to the first electric capacity of human body touch, for the second electric capacity of reference voltage is provided, and anti-phase ratio amplifying circuit, wherein, the positive pole of described the first electric capacity is connected to the first input end of anti-phase ratio amplifying circuit, and the positive pole of described the second electric capacity is connected to the second input of anti-phase ratio amplifying circuit; Described anti-phase ratio amplifying circuit compares and enlarges the voltage difference of the first electric capacity and the second electric capacity, and exports a magnitude of voltage to described processing module.
2. testing circuit as claimed in claim 1, it is characterized in that, described detection module also comprises the first power supply circuits that are used to described the first capacitor charging, with the second power supply circuits that are used to described the second capacitor charging, wherein, the input of the input of described the first power supply circuits and the second power supply circuits is connected to external dc power, and the output of described the first power supply circuits is connected to the positive pole of the first electric capacity, and the output of described the second power supply circuits is connected to the positive pole of the second electric capacity.
3. testing circuit as claimed in claim 2, is characterized in that, described the first power supply circuits comprise the first current source, and the input of described the first current source is connected with external dc power, and output is connected with the positive pole of the first electric capacity; Described the second power supply circuits comprise the second current source, and the input of described the second current source is connected with external dc power, and output is connected with the positive pole of the second electric capacity.
4. testing circuit as claimed in claim 3, it is characterized in that, described detection module also comprises charging control circuit, described charging control circuit comprises the first switching circuit, second switch circuit and the 3rd switching circuit, wherein, described the first switching circuit, second switch circuit and the 3rd switching circuit all are connected with external ac power source; When external ac power source is low level, described second switch circuit and the 3rd switching circuit disconnect, described the first switching circuit conducting also makes described the first current source and external dc power conducting, and described the first power supply is to the first capacitor charging, and described second source is to the second capacitor charging; When external ac power source is high level, described the first switching circuit disconnects, described second switch circuit and the 3rd switching circuit conducting, described the first electric capacity and the second capacitor discharge.
5. testing circuit as claimed in claim 1, it is characterized in that, described detection module also comprises sampling hold circuit, and the input of described sampling hold circuit is connected with the output of described anti-phase ratio amplifying circuit, and the output of described sampling hold circuit is connected to described processing module; Described sampling hold circuit is sampled and is stored the output signal of anti-phase ratio amplifying circuit, and is sent to described processing module.
6. testing circuit as claimed in claim 5, it is characterized in that, described sampling hold circuit comprises the first transmission gate circuit and the 3rd electric capacity of being stored for the magnitude of voltage to sampling, described the first transmission gate circuit comprises the first control end, the second control end, input and output, wherein, described external ac power source is connected with described the first control end, described external ac power source is connected with described the second control end through inverter, the input of described the first transmission gate circuit is connected with the output of described anti-phase ratio amplifying circuit, the output of described the first transmission gate circuit is connected with the input of described the 3rd electric capacity and described processing module, described external ac power source is controlled the first transmission gate circuit conducting, and the first transmission gate circuit is sampled and is stored to described the 3rd electric capacity the voltage of described anti-phase ratio amplifying circuit output, and the magnitude of voltage of described the 3rd capacitance stores exports described processing module to.
7. testing circuit as claimed in claim 1, is characterized in that, described detection module also comprises the first amplifying circuit and the second amplifying circuit for improving the voltage driving force; Wherein, the input of described the first amplifying circuit is connected with the positive pole of described the first electric capacity, and output is connected with the first input end of described anti-phase ratio amplifying circuit; The input of described the second amplifying circuit is connected with the positive pole of described the second electric capacity, and output is connected with the second input of described anti-phase ratio amplifying circuit.
8. testing circuit as claimed in claim 7, it is characterized in that, described the first amplifying circuit and the second amplifying circuit are buffer circuits, described buffer circuits comprises a P type metal-oxide-semiconductor and the first N-type metal-oxide-semiconductor, wherein, the source electrode of a described P type metal-oxide-semiconductor is connected with external dc power, and the drain electrode of a described P type metal-oxide-semiconductor is connected with the drain electrode of described the first N-type metal-oxide-semiconductor and as output, and the grid of a P type metal-oxide-semiconductor is connected to the grid of the first N-type metal-oxide-semiconductor and as input; The source ground of described the first N-type metal-oxide-semiconductor.
9. testing circuit as claimed in claim 1, it is characterized in that, described anti-phase ratio amplifying circuit comprises operational amplifier, the first resistance, the second resistance, the 3rd resistance and the 4th resistance, wherein, described the first resistance one end is connected to the positive input terminal of operational amplifier, and the other end is as the first input end of anti-phase ratio amplifying circuit; Described the second resistance one end is connected to the negative input end of operational amplifier, and the other end is as the second input of anti-phase ratio amplifying circuit; The positive input terminal of described operational amplifier is through the 3rd grounding through resistance; Described the 4th resistance one end is connected to the negative input end of operational amplifier, and the other end is connected to the output of operational amplifier and as the output of anti-phase ratio amplifying circuit.
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| CN201310404940.2A CN103475352B (en) | 2013-09-06 | 2013-09-06 | The detection circuit of capacitance touch button |
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| CN201310404940.2A CN103475352B (en) | 2013-09-06 | 2013-09-06 | The detection circuit of capacitance touch button |
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Cited By (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2015131329A1 (en) * | 2014-03-04 | 2015-09-11 | Nokia Technologies Oy | Method and apparatus for capacitive sensing |
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| 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 |
| CN112415604A (en) * | 2021-01-22 | 2021-02-26 | 深圳市汇顶科技股份有限公司 | Detection circuit, chip and related electronic device |
| 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 |
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