CN110161318A - A kind of capacitive detection circuit and detection method - Google Patents
A kind of capacitive detection circuit and detection method Download PDFInfo
- Publication number
- CN110161318A CN110161318A CN201810149331.XA CN201810149331A CN110161318A CN 110161318 A CN110161318 A CN 110161318A CN 201810149331 A CN201810149331 A CN 201810149331A CN 110161318 A CN110161318 A CN 110161318A
- Authority
- CN
- China
- Prior art keywords
- capacitance
- self
- detected
- resistance chain
- resistance
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R27/00—Arrangements for measuring resistance, reactance, impedance, or electric characteristics derived therefrom
- G01R27/02—Measuring real or complex resistance, reactance, impedance, or other two-pole characteristics derived therefrom, e.g. time constant
- G01R27/26—Measuring inductance or capacitance; Measuring quality factor, e.g. by using the resonance method; Measuring loss factor; Measuring dielectric constants ; Measuring impedance or related variables
- G01R27/2605—Measuring capacitance
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Electronic Switches (AREA)
- Measurement Of Resistance Or Impedance (AREA)
Abstract
Denomination of invention: the invention proposes a kind of capacitive detection circuits, including N number of capacitance detecting electrode, M resistance, switch module and self-capacitance detection module for a kind of capacitive detection circuit and detection method.N number of capacitance detecting electrode, which is connected in the resistance chain that M resistance is connected into, forms resistance chain to be detected, is connected to self-capacitance detection module via switch module.It is controlled by switch module, two incoming ends of resistance chain to be detected are separately connected the detection port of self-capacitance detection module and in high-impedance state, measure a capacitor count value, and after cycle time, two incoming end exchanges measure another count value.When there is touch action, changes will occur for the two count values, the ratio of the variable quantity by calculating the two count values, it can be determined that the detecting electrode for going out which position in resistance chain is touched.The present invention changes the mode of capacitive detection circuit detection port and the one-to-one detection of detecting electrode in current art, is detected using less capacitive detection circuit port to multiple detecting electrodes, reduces production cost.
Description
Technical field
The present invention relates to capacitance measurement technique field, in particular to a kind of capacitive detection circuit and measurement method.
Background technique
Currently, capacitance type touch key obtains widely in fields such as household electrical appliances, body-building equipment, smart home, Industry Controls
Using.Existing technology is by by the one-to-one detection port for being connected to capacitive detection circuit of capacitance detecting electrode, realizing pair
Capacitance variations on capacitance detecting electrode are detected, to realize the detection and judgement to movements such as finger touch key-press.Such as
Fruit detects multiple capacitance type touch keys, it is necessary to occupy the computing capability of considerable port resource and processor.
Summary of the invention
To overcome existing capacitance measurement technique to occupy the defect of excessive detection circuit resource.The present invention proposes a kind of using
The technology that multiple capacitance detecting electrodes are detected in the case where less capacitive detection circuit detection port and computing resource
Scheme.
The invention proposes a kind of capacitive detection circuits, by N number of capacitance detecting electrode, M resistance, switch module, certainly electricity
Hold detection module to constitute, wherein M, N are the integer more than or equal to 2.
M resistance is composed in series series resistance chain in circuit, and N number of capacitance detecting electrode to be detected is connected to according to actual needs
Between each resistance, this N number of capacitance detecting electrode and M resistance form resistance chain to be detected.Distinguish at the both ends of resistance chain to be detected
It is named as the end resistance chain incoming end A to be detected and the end incoming end B.
Switch module includes two switches, and two switches respectively take an incoming end to link together and form connecing for switch module
Enter and hold C-terminal, another incoming end of two switches is respectively designated as the end incoming end X and the end incoming end Y of switch module.
The incoming end C-terminal of switch module is connected with the detection port of self-capacitance detection module, the end incoming end X of switch module
The side a and b of resistance chain to be detected is separately connected with the end incoming end Y, in this way composition capacitive detection circuit.
Two switches in switch module in the capacitive detection circuit turn on and off alternatively, and switch 1 is on shape
When state, switch 2 must be in an off state, and the end resistance chain A to be detected is connect with the detection port of self-capacitance detection module at this time, to
The detection resistance end chain B is in high-impedance state；When switch 2 in switch module is in the conductive state, switch 1 must be in disconnection shape
State, the end resistance chain B to be detected are connect with the detection port of self-capacitance detection module, and the end resistance chain A to be detected is in high-impedance state.
Detection method matched with above-mentioned detection circuit is: two switches of switch module replace in an ON state, and
The capacitor count value under both of these case is obtained with self-capacitance detection module.When there is touch action, capacitance size can become
Change, thus the changing value Δ N of the capacitor count value of the self-capacitance detection module under obtaining both of these caseXLWith Δ NXR。
The present invention discloses Δ NXLWith Δ NXRThe ratio between Δ NXL/ΔNXRIn the ideal case completely by the changed electricity of capacitor
Hold detecting electrode to determine in the on-position of resistance chain to be detected, the capacitance variations degree etc. caused with key weight, movement its
His factor is unrelated.
The Δ N in the embodiment of the present invention 1XL/ΔNXR= (VH-VL-I*RXR)/ (VH-VL-I*RXL), wherein VH, VL, I
For constant, RXRAnd RXLIt is the resistance of capacitance detecting electrode two incoming end side a and bs of distance in resistance chain to be detected respectively
Value, the ratio between capacitor count difference value of self-capacitance detection module is by RXRAnd RXLIt determines.Therefore by ratios delta NXL/ΔNXRIt knows to occur
Capacitance variations are which of N number of capacitance detecting electrodes.
The Δ N in the embodiment of the present invention 2XLWith Δ NXRThe ratio between Δ NXL/ΔNXRValue equally by capacitance detecting electrode to
The on-position of detection resistance chain determines.In actual application, when finger touches different capacitance detecting electrodes, measurement and
Record the ratios delta N of counting of charging/discharging difference when self-capacitance detection module switchs alternately in an ON state at twoXL/ΔNXR,
This ratio is established into table.This table is looked by counter, so that it may which the ratio between the count difference value obtained by actual measurement is found
It is which capacitance detecting electrode is touched.To realize the detection port for passing through a capacitive detection circuit, N number of capacitor inspection is detected
Survey the purpose of electrode variation.
The beneficial effects of the present invention are: the present invention using a small amount of capacitive detection circuit port, realizes pair
The detection of multiple capacitance detecting electrodes, substantially increases the utilization rate of capacitive detection circuit port, reduces production cost.
Detailed description of the invention
Present invention will be further explained below with reference to the attached drawings and examples.
Fig. 1 is the structural schematic diagram of capacitive detection circuit of the invention.
Fig. 2 is the circuit diagram of 1 capacitive detection circuit of embodiment.
Fig. 3 is the capacitance voltage variation diagram to be detected of embodiment 1.
Approximate equivalent circuit when Fig. 4 is the conducting of 1 switch 1 of embodiment, switch 2 ends.
Approximate equivalent circuit when Fig. 5 is the conducting of 1 switch 2 of embodiment, switch 1 ends.
Fig. 6 is the circuit diagram of 2 capacitive detection circuit of embodiment.
Fig. 7 is the circuit diagram of 3 capacitive detection circuit of embodiment.
Specific embodiment
Illustrate the present invention in order to clearer, the following discloses examples of implementation, the example of embodiment is shown in the accompanying drawings.All realities
It is merely illustrative to apply example, the present invention is not to be limited only to embodiment.
[embodiment 1]
Resistance chain and switch module to be detected in this embodiment are same as above described in summary of the invention, see Fig. 2.
Self-capacitance detection module in this embodiment is designed specifically to self-capacitance detection module 1, by detection port, switch
SW3, SW4, two comparators, logic control element, counter composition.
The working principle of self-capacitance detection module 1 in this embodiment: SW3 conducting, SW4 cut-off, current source I1 is to detection
Port capacitor charging.When capacitance voltage reaches reference voltage VH, SW3 cut-off, SW4 conducting, current source I2, which gives, detects port electricity
Discharge capacitor.When capacitor port voltage reaches reference voltage VL, SW3 conducting, SW4 cut-off repeats above-mentioned charge and discharge process.One
It fixes time in T, the size of the number reaction capacitor of charge and discharge.To realize the detection of capacitor.Detection port voltage waveform such as Fig. 3
It is shown.
Charging and discharging electric current source size is I, and detecting the capacitor on port is C, then each charge and discharge time is t=2*C*
(VH-VL)/I, in some cycles (cycle duration T), counting N=T/t=T*I/ (2*C* (V of counterH-VL))
In this embodiment, detection method is as follows.
Self-capacitance detection module is connected by switch module with resistance chain to be detected, periodically alternately with the following two stage
Measure circuit under test capacitor.
Stage 1: SW1 is connected in switch module, SW2 cut-off, the self-capacitance being connected with the end incoming end A of resistance chain to be detected
Detection module 1 starts counting in cycle T, and the end incoming end B of resistance chain to be detected is hanging.Then when have finger touch capacitance detecting
Electrode ELCTXWhen, circuit Approximate Equivalent is Fig. 4.
If RXL=R1+R2+…+RX, then this stage charge and discharge counting how many times is NXL:
NXL= T*I/(2*C*(VH-VL-I*RXL)) --- formula 1.
Stage 2: SW2 is connected in switching group, SW1 cut-off, the self-capacitance inspection being connected with the end incoming end B of resistance chain to be detected
It surveys module 1 to start counting in cycle T, the end incoming end A of resistance chain to be detected is hanging.It is then electric when there is finger to touch capacitance detecting
Pole ELCTXWhen, circuit Approximate Equivalent is Fig. 5.
If RXR=RX+1+RX+2+…+RN+1, then this stage charge and discharge counting how many times NXR:
NXR= T*I/(2*C*(VH-VL-I*RXR)) --- formula 2.
Assuming that finger does not touch capacitance detecting electrode ELCTXWhen, ELCTXOn equivalent capacity be CX.After finger touches,
Equivalent capacity becomes CX+ΔC。
Then at stage 1, finger is obtained by formula 1 and touches front and back, 1 charge and discharge counting how many times difference of self-capacitance detection module
Are as follows:
ΔNXL= T*I/(2*(CX+ΔC)*(VH-VL-I*RXL))-T*I/(2*CX*(VH-VL-I*RXL))
ΔNXL= T*I*ΔC/(2CX*(CX+ΔC)*(VH-VL-I*RXL)) --- formula 3.
Similarly, then at stage 2, finger is obtained by formula 2 and touches front and back, 1 charge and discharge number meter of self-capacitance detection module
Number difference are as follows:
ΔNXR= T*I*ΔC/(2CX*(CX+ΔC)*(VH-VL-I*RXR)) --- formula 4.
It can be obtained by formula 3 and formula 4, two stage charge and discharge number variations are than Δ NXL/ΔNXR:
ΔNXL/ΔNXR=(VH-VL-I*RXR)/ (VH-VL-I*RXL) 。
So far available conclusion, VH, VL, I is constant, and the ratio between count difference value of self-capacitance detection module is by RXRAnd RXLCertainly
It is fixed.It is determined by the position that capacitance detecting electrode to be detected accesses in resistance chain to be detected, with capacitance variations journey to be detected
It spends unrelated, that is to say, that unrelated close to the degree of capacitance detecting electrode to be detected with finger.Therefore electricity occurs known to the ratio
Which capacitance detecting electrode hold variation is.
[embodiment 2]
Resistance chain and switch module to be detected in this embodiment are same as above described in summary of the invention.
Self-capacitance detection module in this embodiment is designed specifically to self-capacitance detection module 2, self-capacitance detection module 2 by
Port, switch SW3, SW4, SW5, comparator are detected, logic control element, counter form, as shown in Figure 6.
The capacitance detecting process of self-capacitance detection module 2 is as follows, and when sampling starts every time, SW5 conducting puts capacitor Cx
Electricity.Then SW5 ends, and starts charge transfer process.
SW3 first is connected in charge transfer process, SW4 cut-off, makes to detect port capacitor charging to supply voltage, then
SW3 cut-off, SW4 conducting make to detect in the electric charge transfer to CX capacitor on the capacitor of port, repeat above-mentioned electric charge transfer step, make
It obtains voltage on CX and reaches Voltage Reference Vref, the count value of this hour counter has recorded the number of electric charge transfer.This count value
Detection port capacitance size is reacted, to realize the detection of capacitor.
Same summary of the invention, this detection method make SW1, SW2 periodicity alternate conduction and cut-off in switching group, both not
Measure the count difference value Δ N of electric charge transfer with self-capacitance detection module 2 respectively with the stageXLWith Δ NXR, and calculate two differences it
Than Δ NXL/ΔNXR, this ratio is established into table.This table is looked by counter, so that it may by the ratio between count difference value, be found
It is which capacitance detecting electrode is touched.
[embodiment 3]
The capacitive detection circuit of embodiment 3 is by N number of capacitance detecting electrode, M resistance, switch module, self-capacitance detection module structure
At.
Resistance chain to be detected in this embodiment is as shown in Figure 7.
M resistance in this embodiment is divided into 3 groups, and every group is connected into a resistance chain, respectively resistance chain 1, resistance chain 2
With resistance chain 3.3 resistance chains have one end to be connected to one piece, and the other end of 3 resistance chains is respectively designated as the end A1, the end A2 and A3
End.N number of capacitance detecting electrode to be detected is connected to according to actual needs between each resistance, this N number of capacitance detecting electrode and M resistance
Form resistance chain to be detected.
Switch module includes 3 switches, respectively takes an input terminal of 3 switches to link together, forms switch module
Incoming end C-terminal, incoming end X, Y and the Z of 3 another incoming ends switched respectively as switch module.
The incoming end C-terminal of switch module is connected with self-capacitance detection module, the end incoming end X, the Y and Z difference of switch module
The end A1, the end A2 and the end A3 of resistance chain to be detected are connected, in this way composition capacitive detection circuit.
Self-capacitance detection module in this embodiment is designed as self-capacitance detection module 1.
In this embodiment, detection method is as follows.
Self-capacitance detection module is connected by switching group with resistance chain to be detected, 3 in periodical alternate change switching group
Switch state, to undergo following 3 phase measurings circuit under test capacitor.
Stage 1: SW1 is connected in switching group, and SW2, SW3 cut-off, self-capacitance detection module 1 are started counting in cycle T, obtained
To the changes delta N1 of finger charge and discharge number when close.
Stage 2: SW2 is connected in switching group, and SW1, SW3 cut-off, self-capacitance detection module 1 are started counting in cycle T, obtained
To the changes delta N2 of finger charge and discharge number when close.
Stage 3: SW3 is connected in switching group, and SW1, SW2 cut-off, self-capacitance detection module 1 are started counting in cycle T, obtained
To the changes delta N3 of finger charge and discharge number when close.
Must be identical there are two being worth in Δ N1, Δ N2 and Δ N3, if Δ N1 is different from other two values, the electricity touched
Holding detecting electrode is the capacitance detecting electrode accessed in resistance chain 1, and position can (charge and discharge number changes by Δ N1/ Δ N2
The ratio between) determine.If Δ N2 or Δ N3 is different from other two values, ibid handle.
The embodiments described above only express several embodiments of the present invention, and the description thereof is more specific and detailed, but simultaneously
Limitations on the scope of the patent of the present invention therefore cannot be interpreted as.It should be pointed out that for those of ordinary skill in the art
For, without departing from the inventive concept of the premise, various modifications and improvements can be made, these belong to guarantor of the invention
Protect range.
Claims (5)
1. a kind of capacitive detection circuit characterized by comprising
M resistance forms a series resistance chain, wherein M is the integer more than or equal to 2；
N number of capacitance detecting electrode, is connected into the different location of series resistance chain respectively, wherein N is more than or equal to 2 and whole less than M
Number；
Self-capacitance detection module；
The switch module of two switch compositions, for control self-capacitance detection module and series resistance chain circuit incoming end whether
Connection.
2. capacitive detection circuit as described in claim 1, which is characterized in that M resistance can be composed in series a resistance chain,
N number of capacitance detecting electrode is respectively connected to wherein different location and forms resistance chain to be detected, and there are two incoming end A for resistance chain to be detected
End and the end B.
3. the self-capacitance detection module in capacitive detection circuit as described in claim 1, which is characterized in that self-capacitance detects mould
Block can be detected the capacitance size on port and be converted to its internal count value, and it is big to react capacitance by count value size
It is small.
4. capacitive detection circuit as described in claim 1, which is characterized in that switch module is made of two switches, and two are opened
Alternate conduction and cut-off are closed, two incoming end side a and bs for controlling resistance chain to be detected are alternately connect with self-capacitance detection module
Or it is in high-impedance state.
5. capacitive detection circuit as described in claim 1, which is characterized in that it is controlled by switch module, resistance chain to be detected
Two incoming ends are separately connected the detection port of self-capacitance detection module and in high-impedance states, measure a capacitor count value,
After cycle time, two incoming end exchanges measure another capacitor count value；When there is touch action, the two capacitors are counted
Changes will occur for value, calculates the ratios delta N of the variable quantity of the two capacitor count valuesXL/ΔNXR, the ratio only and RXRAnd RXL
It is related, RXRAnd RXLIt is the resistance value of capacitance detecting electrode two incoming end side a and bs of distance in series resistance chain respectively, by
Capacitance variations occur known to the ratio is which of N number of testing capacitance detecting electrode, it can accurately judges finger
Touch action.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810149331.XA CN110161318B (en) | 2018-02-13 | 2018-02-13 | Capacitance detection circuit and detection method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810149331.XA CN110161318B (en) | 2018-02-13 | 2018-02-13 | Capacitance detection circuit and detection method |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN110161318A true CN110161318A (en) | 2019-08-23 |
| CN110161318B CN110161318B (en) | 2021-01-26 |
Family
ID=67635346
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201810149331.XA Active CN110161318B (en) | 2018-02-13 | 2018-02-13 | Capacitance detection circuit and detection method |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN110161318B (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110411535A (en) * | 2019-08-27 | 2019-11-05 | 谢晔华 | A kind of capacitance type liquid level detection circuit and detection method |
| CN112363003A (en) * | 2020-11-26 | 2021-02-12 | 深圳市汇顶科技股份有限公司 | Self-capacitance detection circuit, touch chip and electronic equipment |
| CN114209095A (en) * | 2021-12-30 | 2022-03-22 | 西安稳先半导体科技有限责任公司 | Battery protection circuit, battery pack and electronic device |
| CN114397977A (en) * | 2022-02-26 | 2022-04-26 | 谢晔华 | Capacitance induction type input detection device |
Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20050068045A1 (en) * | 2003-09-30 | 2005-03-31 | Aisin Seiki Kabushiki Kaisha | Capacitance detection apparatus |
| CN201251612Y (en) * | 2008-03-19 | 2009-06-03 | 杜波 | Structure for realizing detection of multiple capacitive touch sensors |
| CN103109196A (en) * | 2010-07-09 | 2013-05-15 | 科恩托罗尼丝株式会社 | Method and device for sensing capacitance change and recording medium in which program for executing method is recorded thereon, and method and device for sensing touch using method and recording medium in which program for executing method is record |
| US20140172336A1 (en) * | 2012-12-19 | 2014-06-19 | Continental Automotive Gmbh | Device for measuring the variation of a capacitance and associated measuring method |
| CN106055183A (en) * | 2012-12-30 | 2016-10-26 | 比亚迪股份有限公司 | Capacitance detection circuit |
| CN106841820A (en) * | 2017-03-24 | 2017-06-13 | 湖北工程学院 | Multrirange capacitance measurement circuit, device and method |
| CN107543972A (en) * | 2017-09-08 | 2018-01-05 | 乐鑫信息科技（上海）有限公司 | One kind measurement capacitor system and its measuring method |
-
2018
- 2018-02-13 CN CN201810149331.XA patent/CN110161318B/en active Active
Patent Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20050068045A1 (en) * | 2003-09-30 | 2005-03-31 | Aisin Seiki Kabushiki Kaisha | Capacitance detection apparatus |
| CN201251612Y (en) * | 2008-03-19 | 2009-06-03 | 杜波 | Structure for realizing detection of multiple capacitive touch sensors |
| CN103109196A (en) * | 2010-07-09 | 2013-05-15 | 科恩托罗尼丝株式会社 | Method and device for sensing capacitance change and recording medium in which program for executing method is recorded thereon, and method and device for sensing touch using method and recording medium in which program for executing method is record |
| US20140172336A1 (en) * | 2012-12-19 | 2014-06-19 | Continental Automotive Gmbh | Device for measuring the variation of a capacitance and associated measuring method |
| CN103883180A (en) * | 2012-12-19 | 2014-06-25 | 法国大陆汽车公司 | Device for measuring a variation of a capacitance and associated measuring method |
| CN106055183A (en) * | 2012-12-30 | 2016-10-26 | 比亚迪股份有限公司 | Capacitance detection circuit |
| CN106841820A (en) * | 2017-03-24 | 2017-06-13 | 湖北工程学院 | Multrirange capacitance measurement circuit, device and method |
| CN107543972A (en) * | 2017-09-08 | 2018-01-05 | 乐鑫信息科技（上海）有限公司 | One kind measurement capacitor system and its measuring method |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110411535A (en) * | 2019-08-27 | 2019-11-05 | 谢晔华 | A kind of capacitance type liquid level detection circuit and detection method |
| CN112363003A (en) * | 2020-11-26 | 2021-02-12 | 深圳市汇顶科技股份有限公司 | Self-capacitance detection circuit, touch chip and electronic equipment |
| CN112363003B (en) * | 2020-11-26 | 2023-07-04 | 深圳市汇顶科技股份有限公司 | Self-capacitance detection circuit, touch chip and electronic equipment |
| CN114209095A (en) * | 2021-12-30 | 2022-03-22 | 西安稳先半导体科技有限责任公司 | Battery protection circuit, battery pack and electronic device |
| CN114209095B (en) * | 2021-12-30 | 2024-04-26 | 西安稳先半导体科技有限责任公司 | Battery protection circuit, battery pack and electronic device |
| CN114397977A (en) * | 2022-02-26 | 2022-04-26 | 谢晔华 | Capacitance induction type input detection device |
Also Published As
| Publication number | Publication date |
|---|---|
| CN110161318B (en) | 2021-01-26 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN110161318A (en) | A kind of capacitive detection circuit and detection method | |
| CN104428680B (en) | The capacitance measurement circuit of touch sensor and the capacitance contact board with the capacitance measurement circuit | |
| TWI630533B (en) | Capacitive fingerprint sensor with integrator | |
| CN102200869B (en) | Capacitance type touch control device and sensing device thereof | |
| CN101477152B (en) | Capacitance detection apparatus and method | |
| CN208506138U (en) | Capacitive detection circuit, touch detecting apparatus and terminal device | |
| CN101893972A (en) | Sensing method of a capacitance type touch control screen and driving circuit | |
| CN102375625B (en) | The sensing circuit of capacitive touch control plate and method | |
| CN110596465B (en) | Capacitance detection circuit, touch device and terminal equipment | |
| CN109496273A (en) | Capacitive detection circuit, touch detecting apparatus and terminal device | |
| CN107543972A (en) | One kind measurement capacitor system and its measuring method | |
| CN107980142A (en) | A kind of fingerprint recognition circuit, fingerprint sensor and mobile terminal | |
| TWI339356B (en) | ||
| CN201707661U (en) | Mutual capacitance detection circuit | |
| CN214473623U (en) | Capacitance detection circuit | |
| CN101847070B (en) | Capacitance change detection module taking electric signal change time as detection target | |
| CN102253289A (en) | Electric capacity measuring device for touch control device | |
| CN103823598A (en) | Touch sensing circuit and touch sensing method | |
| CN201382977Y (en) | Capacitor measuring device | |
| CN108614161A (en) | A kind of capacitance measurement system | |
| CN108711392A (en) | A kind of naked glass panel, capacitive detection circuit and capacitance determining method | |
| TWI400456B (en) | Used in capacitive touch buttons and proximity sensing sensing circuits and methods | |
| CN100414305C (en) | Light control electronic switch type automatic function selecting universal meter | |
| CN200975924Y (en) | Digital automatic temperature measuring equipment | |
| CN108226649A (en) | Capacitance detecting device and method |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |