CN103914190A - Capacitance detection circuit - Google Patents
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- CN103914190A CN103914190A CN201210591522.4A CN201210591522A CN103914190A CN 103914190 A CN103914190 A CN 103914190A CN 201210591522 A CN201210591522 A CN 201210591522A CN 103914190 A CN103914190 A CN 103914190A
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Abstract
The invention provides a capacitance detection circuit. The capacitance detection circuit comprises N induction units, a transfer capacitor, a charging module for charging the transfer capacitor and a controller, wherein the N is an integer larger than or equal to 1, one end of the transfer capacitor is respectively connected with the N induction units, the other end of the transfer capacitor is grounded, the transfer capacitor is used for transferring charge to capacitors in scanned induction units in the N induction units, the charging module comprises a first switch and a first resistor which are connected in series, the controller is respectively connected with the charging module and the transfer capacitor and used for controlling turn-off of a first switch when voltage of the transfer capacitor is larger than a preset threshold value, controlling turn-off of the first switch and meanwhile updating a count value when voltage of the transfer capacitor is smaller than the preset threshold value and detecting the touch condition of the N induction units according to the count value. The capacitance detection circuit can eliminate the capacitor influence, accordingly improve the detection accuracy and greatly improve the judgment accuracy.
Description
Technical field
The present invention relates to capacitance detecting technical field, particularly a kind of capacitive detection circuit.
Background technology
At present, touch-screen is in mobile phone, PDA(personal digital assistant), GPS(GPS), PMP(MP3, MP4 etc.) or even the electronic equipment such as panel computer in obtained application.Touch-screen has advantages of that touch control operation is simple, convenient, hommization, and therefore touch-screen is expected to become the best interface of human-computer interaction and is widely applied in portable set.And along with the widespread use of touch-screen, people are also more and more deep to the research of touch screen technology.
In prior art, judge by detecting the size of sensing unit self-capacitance in touch-screen whether sensing unit is touched often, therefore how accurately to detect the self-capacitance that the sensing unit in touch-screen produces in the time being touched and become very important.
And the shortcoming that existing capacitance detecting principle exists is, in the time that detection sensing unit is touched the electric capacity producing, due to the existence of mutual capacitance, often be subject to the impact of mutual capacitance, while causing detecting, produce certain error, therefore, accuracy of detection is not high enough, and then can not accurately judge whether sensing unit is touched.
Summary of the invention
Object of the present invention is intended at least solve one of above-mentioned technological deficiency.
For this reason, the object of the invention is to propose a kind of capacitive detection circuit, can eliminate the impact of mutual capacitance, thereby improved accuracy of detection, accuracy of judgement degree also improves greatly.
For achieving the above object, embodiments of the invention have proposed a kind of capacitive detection circuit, comprising: N sensing unit, and wherein, N is more than or equal to 1 integer; Shift electric capacity, one end of described transfer electric capacity is connected with a described N sensing unit respectively, the other end ground connection of described transfer electric capacity, and described transfer electric capacity is used for the electric charge of self to be transferred in the electric capacity of the sensing unit that a described N sensing unit is scanned; Charging module, one end of described charging module is connected with one end of described transfer electric capacity, and the other end of described charging module is connected with the first power supply, for described transfer electric capacity is charged, wherein, described charging module comprises the first switch and first resistance of series connection; Controller, described controller is connected with described transfer electric capacity with described charging module respectively, described controller is in the time that the voltage of described transfer electric capacity is greater than predetermined threshold value, controlling described the first switch turn-offs, upgrade count value simultaneously, and detect the touch situation of a described N sensing unit according to described count value.
According to the capacitive detection circuit of the embodiment of the present invention, in the time that being touched the electric capacity producing, can eliminate well detection sensing unit the impact of mutual capacitance, thereby greatly improve accuracy of detection, and then can judge exactly whether sensing unit is touched, and has improved judging nicety rate.
The aspect that the present invention is additional and advantage in the following description part provide, and part will become obviously from the following description, or recognize by practice of the present invention.
Brief description of the drawings
The present invention above-mentioned and/or additional aspect and advantage will become from the following description of the accompanying drawings of embodiments obviously and easily and understand, wherein:
Fig. 1 is according to the structural representation of the capacitive detection circuit of the embodiment of the present invention;
Fig. 2 is according to the circuit theory diagrams of the capacitive detection circuit of the embodiment of the present invention;
Fig. 3 is the circuit theory diagrams of the capacitive detection circuit of an example according to the present invention;
Fig. 4 is the oscillogram of switch controlling signal in capacitive detection circuit according to an embodiment of the invention; With
Fig. 5 is the oscillogram of switch controlling signal in capacitive detection circuit in accordance with another embodiment of the present invention.
Embodiment
Describe embodiments of the invention below in detail, the example of described embodiment is shown in the drawings, and wherein same or similar label represents same or similar element or has the element of identical or similar functions from start to finish.Be exemplary below by the embodiment being described with reference to the drawings, only for explaining the present invention, and can not be interpreted as limitation of the present invention.
Disclosing below provides many different embodiment or example to be used for realizing different structure of the present invention.Of the present invention open in order to simplify, hereinafter the parts to specific examples and setting are described.Certainly, they are only example, and object does not lie in restriction the present invention.In addition, the present invention can be in different examples repeat reference numerals and/or letter.This repetition is in order to simplify and object clearly, itself do not indicate the relation between discussed various embodiment and/or setting.In addition, the various specific technique the invention provides and the example of material, but those of ordinary skill in the art can recognize the property of can be applicable to of other techniques and/or the use of other materials.In addition, First Characteristic described below Second Characteristic it " on " structure can comprise that the first and second Characteristics creations are the direct embodiment of contact, also can comprise the embodiment of other Characteristics creation between the first and second features, such the first and second features may not be direct contacts.
In description of the invention, it should be noted that, unless otherwise prescribed and limit, term " installation ", " being connected ", " connection " should be interpreted broadly, for example, can be mechanical connection or electrical connection, also can be the connection of two element internals, can be to be directly connected, and also can indirectly be connected by intermediary, for the ordinary skill in the art, can understand as the case may be the concrete meaning of above-mentioned term.
With reference to description and accompanying drawing below, these and other aspects of embodiments of the invention will be known.In these descriptions and accompanying drawing, specifically disclose some specific implementations in embodiments of the invention, represent some modes of the principle of implementing embodiments of the invention, but should be appreciated that the scope of embodiments of the invention is not limited.On the contrary, embodiments of the invention comprise all changes, amendment and the equivalent within the scope of spirit and the intension that falls into additional claims.
The capacitive detection circuit proposing according to the embodiment of the present invention is described with reference to the accompanying drawings.
First, as shown in Figure 1, the capacitive detection circuit that the embodiment of the present invention proposes comprises N sensing unit (1,2,3 ... N), shift capacitor C mod, charging module 101 and controller 102.
Wherein, N sensing unit (1,2,3 ... N) in, each sensing unit its electric capacity in the time being touched can change, and N is more than or equal to 1 integer.That is to say, this capacitive detection circuit detects multiple sensing units simultaneously, and wherein multiple sensing units are at least two sensing units.
The one end of as shown in Figure 1, shifting capacitor C mod respectively with N sensing unit (1,2,3 ... N) one end is connected, and shifts the other end ground connection of capacitor C mod, and the other end of sensing unit is also ground connection conventionally.Shift in the capacitor C mod electric capacity for the sensing unit that the electric charge of self is transferred to N sensing unit and is scanned, generally, in the time that sensing unit is touched, it is large that its electric capacity can become.For example, in the time scanning in N sensing unit that sensing unit 1,2,3 is touched, sensing unit 1,2,3 self-capacitance separately change (for example increase), shift capacitor C mod the electric charge of self is transferred to respectively among the self-capacitance of sensing unit 1,2,3, thereby drag down the voltage that shifts capacitor C mod.
One end of charging module 101 is connected with the one end of shifting capacitor C mod, and the other end of charging module 101 is connected with the first power vd, and for charging to shifting capacitor C mod, wherein, charging module 101 comprises the first switch SW 1 and first resistance R 1 of series connection.
Controller 102 is connected with transfer capacitor C mod with charging module 101 respectively, controller 102 is in the time that the voltage of transfer capacitor C mod is greater than predetermined threshold value Vth, control the first switch SW 1 and turn-off, upgrade count value simultaneously, and detect the touch situation of N sensing unit according to count value.That is to say, in the time that the voltage of transfer capacitor C mod is greater than predetermined threshold value Vth, controller 102 is controlled the first switch SW 1 and is disconnected, in the time that the voltage of transfer capacitor C mod is less than predetermined threshold value Vth, controller 102 is controlled the first switch SW 1 closure, simultaneously whether be touched and produce different count values according to sensing unit, detect the touch situation of N sensing unit with this.
Particularly, first controller 102 is by controlling the first switch SW 1, charging module 101 is charged to shifting capacitor C mod, in the time shifting voltage on capacitor C mod higher than predetermined threshold value Vth, controller 102 is controlled the first switch SW 1 and is turn-offed, and in the time shifting voltage on capacitor C mod lower than predetermined threshold value Vth, controller 102 is controlled the first switch SW 1 closure.In the time shifting electric charge on capacitor C mod and transfer to sensing unit, the voltage now shifting on capacitor C mod can be dragged down, and when the electric capacity of sensing unit is larger, voltage draws lowlyer, and the count value of this hour counter is less.After sensing unit is touched, the electric capacity of sensing unit can become greatly, and therefore the count value of counter can become less.That is to say, there is the count value of the sensing unit of touch can be less than the count value of the sensing unit not touching, therefore, can be according to the size of rolling counters forward value, judge whether sensing unit is touched and judge whether which sensing unit in N sensing unit is touched.
Further, in an embodiment of the present invention, as shown in Figure 1, this capacitive detection circuit also comprise N select assembly (1,2,3 ... N), each selection assembly is corresponding with a sensing unit, and be connected to N sensing unit (1,2,3 ... and shift between capacitor C mod N).The switch of that paths of sensing unit corresponding to each selection assembly control.
In one embodiment of the invention, as shown in Figure 2, each selection assembly for example selects assembly 1 further to comprise second switch SW2 and the 3rd switch SW 3.Wherein, second switch SW2 is connected to corresponding sensing unit and shifts between capacitor C mod, and one end of the 3rd switch SW 3 is connected with corresponding sensing unit, and the other end of the 3rd switch SW 3 is connected to the ground, wherein, second switch SW2 and the 3rd switch SW 3 are alternately opened.
And, as shown in Figure 2, each selection assembly for example selects assembly 1 also to comprise the 4th switch SW 4, one end of the 4th switch SW 4 is connected with corresponding sensing unit, the other end of the 4th switch SW 4 is connected with second source VTH, wherein, in one embodiment of the invention, the voltage of second source VTH can be predetermined threshold value Vth.Certainly, in other embodiments of the invention, the voltage of second source VTH also can be other magnitudes of voltage.
Further, in one embodiment of the invention, as shown in Figure 2, this capacitive detection circuit also comprises pre-charge module 201.One end of pre-charge module 201 is connected with the one end of shifting capacitor C mod, and the other end of pre-charge module 201 is connected with the first power vd, and pre-charge module 201 is for carrying out precharge to shifting capacitor C mod.Wherein, pre-charge module 201 comprises the 5th switch SW 5 and second resistance R 2 of mutual series connection.That is to say, to before shifting capacitor C mod charging, also need to carry out precharge to shifting capacitor C mod, the voltage that shifts capacitor C mod is charged in advance near of predetermined threshold value Vth.
In addition, as shown in Figure 2, this capacitive detection circuit also comprises pre-arcing module 202.Pre-arcing module 202 one end are connected with the one end of shifting capacitor C mod, the other end ground connection of pre-arcing module 202, and pre-arcing module 202, for before pre-charge module 201 is to transfer capacitor C mod precharge, is carried out pre-arcing to shifting capacitor C mod.Wherein, pre-arcing module 202 comprises the 6th switch SW 6, by one end ground connection of the 6th switch SW 6, carries out pre-arcing to shifting capacitor C mod.In an embodiment of the present invention, by precharge and the pre-arcing of shifting capacitor C mod, the state that can ensure to shift capacitor C mod in the time of each test is all identical, thereby improves the precision detecting.
In one embodiment of the invention, as shown in Figure 2, controller 102 further comprises comparator C MP, trigger DFF, counter 206, detecting device 203 and first selector 204.Wherein, the first input end of comparator C MP is connected with the voltage Vth of predetermined threshold value, and the second input end of comparator C MP is connected with the one end of shifting capacitor C mod.The input end of trigger DFF is connected with the output terminal of comparator C MP, and for generating trigger pip according to the comparative result of comparator C MP, trigger DFF also comprises clock signal input CNT_CLK.The input end of counter 206 is connected with the output terminal of trigger DFF, for counting according to described trigger pip.Detecting device 203 is connected with counter 206, for detect the touch situation of N sensing unit according to the count value of counter 206.The input end of first selector 204 is connected with the output terminal of trigger DFF, and for generating the first control signal according to the trigger pip of trigger DFF, and the first control signal is used for controlling charging module 101 and charges to shifting capacitor C mod.
In addition, controller 102 also comprises second selector 205.The input end of second selector 205 is connected with the output terminal of comparator C MP, and for generate the second control signal according to comparative result, and the second control signal is used for controlling pre-charge module 201 and carries out precharge to shifting capacitor C mod.
Particularly, as shown in Figure 2, first selector 204 is and door AND, be connected with the output terminal of trigger DFF with the first input end of door AND, with the second input end of door AND with switch enable signal SWITCH EN and be connected.Wherein, in precharge and pre-arcing stage, this enable signal SWITCH EN is low, the first switch SW 1 in charging module 101 is turn-offed, after precharge and pre-arcing, while carrying out the capacitance detecting stage, this signal is high always, the closure of the first switch SW 1 in charging module 101 is controlled by that one end being connected with the output terminal of trigger DFF with shutoff situation, and after detection completes, this enable signal SWITCH EN is again for low.Second selector 205 is rejection gate NOR, and the first input end of rejection gate NOR is connected with the output terminal of comparator C MP, and the second input end of rejection gate NOR is connected with precharging signal PRE_CHRG.
In brief, in an example of the present invention, in the time that sensing unit is one, as shown in Figure 3, as follows to the process of capacitance detecting:
First, carry out pre-arcing to shifting capacitor C mod, first the 6th switch SW 6 closures, the electric charge shifting on capacitor C mod is bled off; Then disconnect the 6th switch SW 6, closed the 5th switch SW 5, the first power vds carry out precharge by the second resistance R 2 to shifting capacitor C mod, until the voltage that shifts capacitor C mod is charged near predetermined threshold value Vth in advance, wherein, in pre-arcing and pre-charging stage, the first switch SW 1 disconnects always.After precharge and pre-arcing finish, the 5th switch SW 5 and the 6th switch SW 6 all disconnect, now control closed the first switch SW 1, the first power vd charges to shifting capacitor C mod by the first resistance R 1, in the time that the voltage on transfer capacitor C mod is predetermined threshold value Vth higher than comparator C MP reference voltage, trigger DFF disconnects according to Output rusults control the first switch SW 1 of comparator C MP.In the time shifting voltage on capacitor C mod lower than predetermined threshold value Vth, comparator C MP upset, trigger DFF is according to Output rusults control the first switch SW 1 closure of comparator C MP.Wherein, in the charge transfer process of transfer capacitor C mod, the electric charge shifting in capacitor C mod passes through second switch SW2, transfers on the capacitor C x of sensing unit.In the time that second switch SW2 disconnects, the voltage shifting on capacitor C mod is pulled down to lower than predetermined threshold value Vth, make comparator C MP upset, by the first switch SW 1 closure, now be charged to higher than predetermined threshold value Vth to transfer capacitor C mod by the first resistance R 1, make comparator C MP upset, the first switch SW 1 is disconnected.Wherein, second switch SW2 and the 3rd switch SW 3 are (to control second switch SW2 when closed by the non-overlapping clock signal control of two-phase, the 3rd switch SW 3 disconnects, and second switch SW2 disconnect time, the 3rd switch SW 3 closures), the 3rd switch SW 3 is put into ground the electric charge of transferring to Cx from transfer capacitor C mod at every turn.The 4th switch SW 4 is synchro switch, and in the time scanning current sensing unit, the 4th switch SW 4 disconnects always.
In the time that sensing unit is touched and is not touched, the capacitor C x of sensing unit varies in size, and the dutycycle of the square wave of trigger DFF output is also different, thereby the count value of counter 206 is also different, judges with this whether sensing unit is touched.After having detected, start again above-mentioned process, so cyclically detect.
Therefore,, by judging the count value of counter 206, can judge sensing unit and whether be touched, and then detecting device 203 can be judged the situation that sensing unit is touched.In an example of the present invention, while supposing that sensing unit is not touched, the count value of counter is 1000, and in the time that sensing unit is touched, the count value of counter is 500, so can judge according to the count value of counter whether sensing unit is touched.
In one embodiment of the invention, under non-full-screen synchronization pattern, as shown in Figure 4, wherein, high level represents gauge tap closure to the waveform of each switch controlling signal, and low level represents that gauge tap disconnects.In the time that M sensing unit is scanned, controller 102 is controlled M and is selected the 4th switch SW 4 in assembly disconnect and control M and select second switch SW2 and the 3rd switch SW 3 in assembly alternately to open, and control N and select second switch SW2, the 3rd switch SW 3 and the 4th switch SW 4 in M other selection assemblies of selecting assembly in assembly all to disconnect, wherein, 1≤M≤N.
In another embodiment of the present invention, under full-screen synchronization pattern, as shown in Figure 5, wherein, high level represents gauge tap closure to the waveform of each switch controlling signal, and low level represents that gauge tap disconnects.In the time that M sensing unit is scanned, controller 102 is controlled M and is selected the 4th switch SW 4 in assembly disconnect and control M and select second switch SW2 and the 3rd switch SW 3 in assembly alternately to open, and control N and select the second switch SW2 in M other selection assemblies of selecting assembly in assembly to disconnect, and control the 3rd switch SW 3 and the 4th switch SW 4 is alternately opened, wherein, 1≤M≤N.That is to say, in the time adopting full-screen synchronization pattern, the 4th switch SW 4 that the current sensing unit being scanned is corresponding disconnects always, and corresponding the 4th switch SW 4 of other synchronous sensing units that are not scanned and second switch SW2 corresponding to the current sensing unit being scanned have identical switch motion, be that second switch SW2 and the 3rd switch SW 3 that the current sensing unit being scanned is corresponding alternately opened, and corresponding the 3rd switch SW 3 and the 4th switch SW 4 of the sensing unit not being scanned alternately opened.Like this, when the current sensing unit being scanned is touched, by second switch SW2 in corresponding selection assembly, the electric charge shifting in capacitor C mod is transferred in the self-capacitance Cx of the current sensing unit being scanned, and for those synchronous sensing units that are not scanned, by the 4th switch SW 4, Cx is charged to specific magnitude of voltage.In an embodiment of the present invention, this specific magnitude of voltage equates with predetermined threshold value Vth.Therefore, the capacitor C x of the current sensing unit being scanned and synchronous those sensing units that are not scanned is charged to predetermined threshold value Vth simultaneously, also discharges into ground by the 3rd switch SW 3 simultaneously, and the impact of eliminating mutual capacitance with this, has improved accuracy of detection.
According to the capacitive detection circuit of the embodiment of the present invention, in the time that being touched the electric capacity producing, can eliminate well detection sensing unit the impact of mutual capacitance, thereby greatly improve accuracy of detection, and then can judge exactly whether sensing unit is touched, and has improved judging nicety rate.
In addition, the each functional unit in each embodiment of the present invention can be integrated in a processing module, can be also that the independent physics of unit exists, and also can be integrated in a module two or more unit.Above-mentioned integrated module both can adopt the form of hardware to realize, and also can adopt the form of software function module to realize.If described integrated module realizes and during as production marketing independently or use, also can be stored in a computer read/write memory medium using the form of software function module.
The above-mentioned storage medium of mentioning can be ROM (read-only memory), disk or CD etc.
In the description of this instructions, the description of reference term " embodiment ", " some embodiment ", " example ", " concrete example " or " some examples " etc. means to be contained at least one embodiment of the present invention or example in conjunction with specific features, structure, material or the feature of this embodiment or example description.In this manual, the schematic statement of above-mentioned term is not necessarily referred to identical embodiment or example.And specific features, structure, material or the feature of description can be with suitable mode combination in any one or more embodiment or example.
Although illustrated and described embodiments of the invention, for the ordinary skill in the art, be appreciated that without departing from the principles and spirit of the present invention and can carry out multiple variation, amendment, replacement and modification to these embodiment, scope of the present invention is by claims and be equal to and limit.
Claims (15)
1. a capacitive detection circuit, is characterized in that, comprising:
N sensing unit, wherein, N is more than or equal to 1 integer;
Shift electric capacity, one end of described transfer electric capacity is connected with a described N sensing unit respectively, the other end ground connection of described transfer electric capacity, and described transfer electric capacity is used for the electric charge of self to be transferred in the electric capacity of the sensing unit that a described N sensing unit is scanned;
Charging module, one end of described charging module is connected with one end of described transfer electric capacity, and the other end of described charging module is connected with the first power supply, for described transfer electric capacity is charged, wherein, described charging module comprises the first switch and first resistance of series connection;
Controller, described controller is connected with described transfer electric capacity with described charging module respectively, described controller is in the time that the voltage of described transfer electric capacity is greater than predetermined threshold value, controlling described the first switch turn-offs, upgrade count value simultaneously, and detect the touch situation of a described N sensing unit according to described count value.
2. capacitive detection circuit as claimed in claim 1, is characterized in that, also comprises:
Select assembly for N, each described selection assembly is corresponding with a described sensing unit, is connected between a described N sensing unit and described transfer electric capacity.
3. capacitive detection circuit as claimed in claim 2, is characterized in that, each described selection assembly further comprises:
Second switch, described second switch is connected between described sensing unit and described transfer electric capacity;
The 3rd switch, one end of described the 3rd switch is connected with described sensing unit, and the other end of described the 3rd switch is connected to the ground, and wherein, described second switch and described the 3rd switch are alternately opened.
4. capacitive detection circuit as claimed in claim 2, is characterized in that, each described selection assembly also comprises:
The 4th switch, one end of described the 4th switch is connected with described sensing unit, and the other end of described the 4th switch is connected with second source, and wherein, the voltage of described second source is described predetermined threshold value.
5. capacitive detection circuit as claimed in claim 1, is characterized in that, also comprises:
Pre-charge module, one end of described pre-charge module is connected with one end of described transfer electric capacity, and the other end of described pre-charge module is connected with described the first power supply, and described pre-charge module is for carrying out precharge to described transfer electric capacity.
6. capacitive detection circuit as claimed in claim 5, is characterized in that, described pre-charge module comprises the 5th switch and second resistance of mutual series connection.
7. capacitive detection circuit as claimed in claim 5, is characterized in that, also comprises:
Pre-arcing module, described pre-arcing module one end is connected with one end of described transfer electric capacity, the other end ground connection of described pre-arcing module, described pre-arcing module, for before described pre-charge module is to the precharge of described transfer electric capacity, is carried out pre-arcing to described transfer electric capacity.
8. capacitive detection circuit as claimed in claim 7, is characterized in that, described pre-arcing module comprises the 6th switch.
9. capacitive detection circuit as claimed in claim 5, is characterized in that, described controller further comprises:
Comparer, the first input end of described comparer is connected with the voltage of described predetermined threshold value, and the second input end of described comparer is connected with one end of described transfer electric capacity;
Trigger, the input end of described trigger is connected with the output terminal of described comparer, for generating trigger pip according to the comparative result of described comparer;
Counter, the input end of described counter is connected with the output terminal of described trigger, for counting according to described trigger pip;
Detecting device, described detecting device is connected with described counter, for detect the touch situation of a described N sensing unit according to the count value of described counter; And
First selector, the input end of described first selector is connected with the output terminal of described trigger, and for generating the first control signal according to the trigger pip of described trigger, described the first control signal is used for controlling described charging module.
10. capacitive detection circuit as claimed in claim 9, is characterized in that, described controller also comprises:
Second selector, the input end of described second selector is connected with the output terminal of described comparer, and for generating the second control signal according to described comparative result, described the second control signal is used for controlling described pre-charge module.
11. capacitive detection circuits as claimed in claim 9, is characterized in that, described first selector is and door, are describedly connected with the first input end of door and the output terminal of described trigger, the second input end of described and door with switch enable signal and be connected.
12. capacitive detection circuits as claimed in claim 10, is characterized in that, described second selector is rejection gate, and the first input end of described rejection gate is connected with the output terminal of described comparer, and the second input end of described rejection gate is connected with precharging signal.
13. capacitive detection circuits as claimed in claim 2, it is characterized in that, under non-full-screen synchronization pattern, in the time that M sensing unit is scanned, M of described controller control is selected the 4th switch in assembly to disconnect and is controlled described M and select described second switch and the 3rd switch in assembly alternately to open, and control and select second switch to the four switches of other selections in assemblies of assembly all to disconnect except described M, wherein, 1≤M≤N.
14. capacitive detection circuits as claimed in claim 2, it is characterized in that, under full-screen synchronization pattern, in the time that M sensing unit is scanned, M of described controller control is selected the 4th switch in assembly to disconnect and is controlled described M and select described second switch and the 3rd switch in assembly alternately to open, and controls other that select assembly except described M and select the second switch disconnection in assemblies, and controls the 3rd switch and the 4th switch replaces unlatching, wherein, 1≤M≤N.
15. capacitive detection circuits as claimed in claim 1, is characterized in that, in the time that described count value is less than the first count threshold and is greater than the second count threshold, judge that the current sensing unit being scanned is touched.
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| CN110463041A (en) * | 2018-03-06 | 2019-11-15 | 深圳市汇顶科技股份有限公司 | Circuit, touch detecting apparatus and terminal device for capacitance detecting |
| CN110463041B (en) * | 2018-03-06 | 2023-08-25 | 深圳市汇顶科技股份有限公司 | Circuit for capacitance detection, touch detection device and terminal equipment |
| CN110504970A (en) * | 2019-08-22 | 2019-11-26 | 湖南品腾电子科技有限公司 | Capacitor digital conversion circuit |
| CN110504970B (en) * | 2019-08-22 | 2023-05-16 | 湖南品腾电子科技有限公司 | Capacitance-to-digital conversion circuit |
| CN112710940A (en) * | 2020-12-23 | 2021-04-27 | 西安交通大学 | SiC MOSFET reverse transfer capacitance measuring method |
| CN112710940B (en) * | 2020-12-23 | 2022-05-20 | 西安交通大学 | SiC MOSFET reverse transfer capacitance measuring method |
| CN115343515A (en) * | 2022-10-17 | 2022-11-15 | 基合半导体（宁波）有限公司 | Analog front end circuit, capacitance measuring circuit, chip and electronic equipment |
| CN115343515B (en) * | 2022-10-17 | 2023-03-07 | 基合半导体（宁波）有限公司 | Analog front end circuit, capacitance measuring circuit, chip and electronic equipment |
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