CN201594117U - Capacitance detection device - Google Patents
Capacitance detection device Download PDFInfo
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- CN201594117U CN201594117U CN2009202614746U CN200920261474U CN201594117U CN 201594117 U CN201594117 U CN 201594117U CN 2009202614746 U CN2009202614746 U CN 2009202614746U CN 200920261474 U CN200920261474 U CN 200920261474U CN 201594117 U CN201594117 U CN 201594117U
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Abstract
Disclosed is a capacitance detection device. A to-be-detected capacitance is a touch capacitance on a capacitance panel. The capacitance detection device comprises a capacitance detection unit connected with the to-be-detected capacitance, a peripheral capacitance of the to-be-detected capacitance on the capacitance panel, a feedback module feeding back voltage of the to-be-detected capacitance to the peripheral capacitance, a charging control module for controlling and charging the to-be-detected capacitance and the peripheral capacitance, a detection control module for controlling the capacitance detection unit to detect the to-be-detected capacitance, and a feedback control module for controlling the feedback module to perform voltage feedback, wherein the feedback module is connected between the to-be-detected capacitance and the peripheral capacitance, the charging control module is connected with the to-be-detected capacitance and the peripheral capacitance, the detection control module is connected with the capacitance detection unit, and the feedback control module is connected with the feedback module. The capacitance detection device feeds back voltage of the to-be-detected capacitance to the peripheral capacitance through the feedback module, reduces affection of a stray capacitance between the to-be-detected capacitance and the peripheral capacitance to the capacitance detection unit, and leas sensibility of the capacitance detection device to be high and detection range to be large.
Description
Technical field
The utility model belongs to the capacitance detecting field, relates in particular to a kind of capacitance detecting device.
Background technology
The application great majority of CapSense (capacitive sensing touch) system are the application of external capacitor screen.Because all there are bigger stray capacitance in the physical arrangement and the employed material of capacitance plate between the horizontal and vertical Sensor (sensor) of most of capacitance plates.Although now the manufacturer of each big capacitance plate reducing the important indicator of stray capacitance as design capacitance screen, on the whole, the stray capacitance on the market on most of capacitance plates is still bigger in process of production.Because the CapSense system is the exigent capacitive detection system of sensitivity, require the capacitance range that detects very little, even can be about 0.1PF or littler (people's finger equivalent capacitance value is at 0.1PF-10PF).Therefore, the stray capacitance on the capacitance plate causes very big influence to the sensitivity meeting that detects, if the stray capacitance on the screen is much larger than detecting capacitance, the detection sensitivity of CapSense system will reduce greatly so.The existence of simultaneously big stray capacitance also can make the sensing range of CapSense system reduce.
Capacitance detection unit in the conventional CapSense system converts testing capacitance and stray capacitance to PWM ripple (pulse-length modulation ripple) by modulator, the variation of testing capacitance can be reflected on the dutycycle of modulator output PWM ripple, utilize counter that the PWM ripple is counted, be reflected to again in the variation of counter code.Use DSP (digital signal processing) module that these codes are handled then, convert coordinate or positional information to, Zhongdao user operable interface.Stray capacitance on the capacitance plate exists always, and the size of different capacitance plate parasitic capacitance values also has very big difference.The CapSense system is when the application of external capacitance plate, and capacitance detection unit not only can detect the touch capacitance on the screen, also can detect the parasitic capacitance value on the screen simultaneously.
Detection sensitivity, sensing range when as mentioned above, present capacitance detection unit connects screen and uses are subject to the stray capacitance on the screen to a great extent.Then need to design and a kind ofly can reduce effectively that stray capacitance obtains the capacitance detecting device highly sensitive, that sensing range is big to the influence of capacitance detection unit on the capacitance plate.
The utility model content
The utility model is for solving the existing technical matters that capacitance detection unit sensitivity is low, sensing range is little, and a kind of highly sensitive, capacitance detecting device that sensing range is big is provided.
A kind of capacitance detecting device, wherein testing capacitance is to touch electric capacity on the capacitance plate, this capacitance detecting device comprises: capacitance detection unit, capacitance detection unit is connected with testing capacitance;
This capacitance detecting device also comprises:
The peripheral electric capacity of testing capacitance on the capacitance plate;
Voltage on the testing capacitance is fed back to the feedback module of peripheral electric capacity;
The charge control module that control testing capacitance, peripheral electric capacity charge;
The detection control module that the control capacitance detecting unit detects testing capacitance;
The Control and Feedback module is carried out the feedback control module of Voltage Feedback;
Feedback module is connected between testing capacitance and the peripheral electric capacity, and charge control module is connected with testing capacitance, peripheral electric capacity; Detecting control module is connected with capacitance detection unit; Feedback control module is connected with feedback module.
Preferably, above-mentioned feedback module is a source follower.
Preferably, above-mentioned source follower is an impact damper.
Preferably, this pick-up unit also comprises: be used to select the mode selection module of stray capacitance mode and general mode, described mode selection module is connected between feedback module and the peripheral electric capacity.
The voltage of the utility model by feedback module feedback testing capacitance is to peripheral electric capacity, reduces stray capacitance between testing capacitance and the peripheral electric capacity to the influence of capacitance detection unit, makes that capacitance detecting device is highly sensitive, sensing range is big.
Description of drawings
Fig. 1 is the capacitance detecting device schematic diagram that the utility model provides;
Fig. 2 is the capacitance detecting device circuit diagram that the utility model embodiment 1 provides;
Fig. 3 is the gauge tap timing waveform of the capacitance detecting device that provides of the utility model embodiment 1;
Fig. 4 is the capacitance detecting device circuit diagram that the utility model embodiment 2 provides;
Fig. 5 is the gauge tap timing waveform of the capacitance detecting device that provides of the utility model embodiment 2.
Embodiment
Clearer for technical matters, technical scheme and beneficial effect that the utility model is solved, below in conjunction with drawings and Examples, the utility model is further elaborated.Should be appreciated that specific embodiment described herein only in order to explanation the utility model, and be not used in qualification the utility model.
The Capsense system is when connecing the screen application, because screen is gone up the existence of stray capacitance, system not only can discharge and recharge testing capacitance, also can the stray capacitance on shielding be discharged and recharged simultaneously, influences the sensitivity of sensing range and system.The described capacitance detecting device of the utility model content is intended to effectively reduce the influence when the CapSense system is connect screen and uses of stray capacitance on the capacitance plate.
Be the capacitance detecting device schematic diagram that the utility model provides as shown in Figure 1, wherein testing capacitance 11 touches electric capacity on the capacitance plate, and this capacitance detecting device comprises peripheral electric capacity 13, feedback module 14, charge control module 15, detection control module 16 and the feedback control module 17 of testing capacitance 11 on capacitance detection unit 12, the capacitance plate.Capacitance detection unit 12 is connected with testing capacitance 11, detects control module 16 and is connected with capacitance detection unit 12, is used for 12 pairs of testing capacitances 11 of control capacitance detecting unit and detects; Feedback module 14 is connected between testing capacitance 11 and the peripheral electric capacity 13, feedback control module 17 is connected with feedback module 14, Control and Feedback module 14 to the pole plate of peripheral electric capacity 13, is eliminated stray capacitance between testing capacitance 11 and the peripheral electric capacity 13 to the influence of capacitance detection unit 12 with the Voltage Feedback of testing capacitance 11; Charge control module 15 is connected with testing capacitance 11, peripheral electric capacity 13, is used to control power supply testing capacitance 11 and peripheral electric capacity 13 are charged.
Preferably above-mentioned feedback module 14 is a source follower, and described source follower is an impact damper.This impact damper has the effect that increases driving force, can also isolate the influence of feedback voltage to capacitance detection unit 12.
As preferred version, this capacitance detecting device also comprises the mode selection module that is used to select stray capacitance mode and general mode, and described mode selection module is connected between feedback module 14 and the feedback control module 17.
This capacitance detecting device is by inserting a feedback circuit of being made up of impact damper and feedback control module 17, electromotive force between the stray capacitance two-plate that produces between testing capacitance 11 and the peripheral electric capacity 13 was consistent in the time period of detecting as far as possible, promptly in the time of detecting, the electric potential difference of stray capacitance two-plate is approximately zero, what the electric charge that shifts can be similar to cancels out each other, and does not have or only have a spot of electric charge transfer on the stray capacitance.According to the detection principle of CapSense system, the actual electric charge of device shifts and only occurs on the electric capacity of wanting to detect like this.This pick-up unit can at utmost reduce on the capacitance plate stray capacitance to the influence of pick-up unit, sensing range and sensitivity in the time of can effectively improving the CapSense system and connect screen and use.
As shown in Figure 2, circuit diagram for the utility model embodiment 1, virtual stray capacitance Cpar is between testing capacitance Cx0 and peripheral capacitor C x1, for convenience of description, only consider and peripheral capacitor C x1 that testing capacitance Cx0 is nearest between virtual stray capacitance Cpar, the peripheral electric capacity contiguous with testing capacitance Cx0 also has a lot, so stray capacitance is also many, can reach the purpose of eliminating other stray capacitances according to this principle design circuit.The first charge switch S1 is connected between power Vcc and the first node 21, and testing capacitance Cx0 is connected between first node 21 and the ground; The second charge switch S2 is connected between power Vcc and the Section Point 22, and peripheral capacitor C x1 is connected between Section Point 22 and the ground; The first detector switch S3 is connected between first node 21 and the 3rd node 23, and capacitance detection unit is connected with the 3rd node 23; Impact damper buffer is connected between the 3rd node 23 and the mode selection switch S4, mode selection switch S4 connects the first feedback switch S5, the first feedback switch S5 connects Section Point 22, constitutes a feedback circuit, reduces the influence of virtual stray capacitance Cpar to capacitance detection unit; Grounding switch S6 is connected between the 4th node 24 and the ground.
The gauge tap timing waveform as shown in Figure 3, this capacitance detecting device by switching sequence control the first charge switch S1, the second charge switch S2 charges to capacitor C x0 to be measured and peripheral capacitor C x1; Controlling the first detector switch S3 detects capacitor C x0 voltage to be measured; Controlling the first feedback switch S5 feeds back the voltage of capacitor C x0 to be measured; Reduce the influence of virtual stray capacitance Cpar to capacitance detection unit; Control model selector switch S4 closure selects to go stray capacitance mode, and control grounding switch S6 disconnects.Below in conjunction with Fig. 2 and Fig. 3 the testing process of this capacitance detecting device is described.
CLK is a clock waveform among Fig. 3, and PH1, PH2 are the two-phase clock that do not overlap, and are produced by the CLk frequency division.S1, S2, S3, S4, S5, S6 are respectively the first charge switch S1 control waveform, the second charge switch S2 control waveform, the first detector switch S3 control waveform, mode selection switch S4 control waveform, the first feedback switch S5 control waveform, grounding switch S6 control waveform.
Testing process to capacitor C x0 to be measured is as follows: mode selection switch S4 is closed always, selects to go stray capacitance mode, is going under the stray capacitance mode, and grounding switch S6 opens always.
When being high, the first charge switch S1, the second charge switch S2 are closed simultaneously at clock PH1, and the first detector switch S3, the first feedback switch S5 open always, and power Vcc is charged to capacitor C x0 to be measured and peripheral capacitor C x1 simultaneously.
At clock PH2 when being high, the first charge switch S1, the second charge switch S2 disconnect simultaneously, the first detector switch S3, the first feedback switch S5 are closed simultaneously, capacitance detection unit carries out voltage acquisition to capacitor C x0 to be measured, simultaneously impact damper buffer with the Voltage Feedback of testing capacitance Cx0 to the pole plate of peripheral capacitor C x1, the electromotive force of two pole plates of virtual like this stray capacitance Cpar can be consistent basically, that is to say that the electric potential difference between two-plate is almost nil, according to formula Q=CU, if U=0, the quantity of electric charge Q of transfer also are zero.So in the whole process that capacitor C x0 to be measured is detected, it is zero that virtual stray capacitance Cpar goes up the quantity of electric charge that shifts.The electric capacity that capacitance detection unit detected only is the capacitance of Cx0, can not detect the capacitance of virtual stray capacitance Cpar, has effectively eliminated the influence of peripheral capacitor C x1 to capacitance detection unit.
When mode selection switch S4 opens always, selected general mode, this moment, this capacitance detecting device did not go the function of stray capacitance, and the second charge switch S2 disconnects, and peripheral capacitor C x1 is not connected with power Vcc, grounding switch S6 closure, the first feedback switch S5 closure with peripheral capacitor C x1 ground connection, is given reference potential of peripheral capacitor C x1 simultaneously, if grounding switch S6 disconnects, then peripheral capacitor C x1 is unsettled.
This capacitance detecting device is by inserting a feedback circuit that has impact damper buffer, mode selection switch S4, first feedback switch S5 composition, electromotive force between stray capacitance Cpar two-plate was consistent in the section in detection time as far as possible, promptly in the time of detecting, electric potential difference between stray capacitance Cpar two-plate is approximately zero, what the electric charge that shifts can be similar to cancels out each other, and does not have or only have a spot of electric charge transfer on the stray capacitance Cpar.According to the detection principle of CapSense system, the actual electric charge of device shifts and only occurs on the electric capacity of wanting to detect like this.This pick-up unit can at utmost reduce on the capacitance plate stray capacitance to the influence of capacitance detection unit, sensing range and sensitivity in the time of can effectively improving the CapSense system and connect screen and use.
As shown in Figure 4, be the circuit diagram of the utility model embodiment 2, the place that two lines intersect among the figure, expression two lines of zone circle do not connect at this place, and expression two lines of zone circle do not link to each other at this place.
Testing capacitance Cx0 and peripheral capacitor C x1 represent the electric capacity on outside two sense channels respectively, and Cpar represents two interchannel virtual stray capacitances, at this for convenience of description, only considers the stray capacitance between adjacent channel.Testing capacitance Cx0, the first charge switch S1, the first detector switch S3, the second feedback switch S7 constitute a Sensor unit among the figure, be equivalent to a sense channel, equally, peripheral capacitor C x1, the second charge switch S2, the second detector switch S8, the first feedback switch S5 have constituted the 2nd Sensor unit.
When capacitor C x0 to be measured is carried out capacitance detecting, the second feedback switch S7, the second detector switch S8 disconnect simultaneously, the disconnection of the first charge switch S1, the second charge switch S2, the first detector switch S3, mode selection switch S4, the first feedback switch S5, grounding switch S6 and closed by the sequential control among Fig. 3, testing process is identical with embodiment 2, so not tired stating.
CLK is a clock waveform among Fig. 5, and PH1, PH2 are the two-phase clock that do not overlap, and are produced by the CLk frequency division.S1, S2, S4, S6, S7, S8 are respectively the first charge switch S1 control waveform, the second charge switch S2 control waveform, mode selection switch S4 control waveform, grounding switch S6 control waveform, the second feedback switch S7 control waveform, the second detector switch S8 control waveform.
When peripheral capacitor C x1 is carried out capacitance detecting, the first feedback switch S5, the first detector switch S3 disconnect simultaneously among Fig. 4, and the gauge tap timing waveform among Fig. 5 is controlled the first charge switch S1, the second charge switch S2 charges to capacitor C x0 to be measured and peripheral capacitor C x1; Controlling the second detector switch S8 detects peripheral capacitor C x1 voltage; Control the second feedback switch S7 voltage of peripheral capacitor C x1 is fed back, control model selector switch S4 selects to go stray capacitance mode; Control grounding switch S6 disconnects; Reduce the influence of virtual stray capacitance Cpar to capacitance detection unit.Testing process is identical with embodiment 2, so not tired stating.
This capacitance detecting device is by inserting a feedback circuit of being made up of impact damper buffer, mode selection switch S4, the second feedback switch S7, electromotive force between stray capacitance Cpar two-plate was consistent in the time period of detecting scanning as far as possible, promptly in the time of detecting scanning, the electric potential difference of stray capacitance Cpar two-plate is approximately zero, what the electric charge that shifts can be similar to cancels out each other, and does not have or only have a spot of electric charge transfer on the stray capacitance Cpar.Like this according to the detection principle of CapSense system, the actual electric charge of capacitance detecting device shifts and only occurs on the electric capacity of wanting to detect, this pick-up unit can at utmost reduce on the capacitance plate stray capacitance to the influence of pick-up unit, sensing range and sensitivity in the time of can effectively improving the CapSense system and connect screen and use.
The shared same feedback module of different testing capacitances reduces circuit area in this capacitance detecting device, effectively saves cost.
In sum, the capacitance detecting device that the utility model content provides can effectively reduce stray capacitance on the capacitance plate to the influence of testing result, the sensing range and the sensitivity that improve capacitance detecting device to greatest extent.This capacitance detecting device is simple in structure, has good performance, is widely used, and is practical.
The above only is preferred embodiment of the present utility model; not in order to restriction the utility model; all any modifications of within spirit of the present utility model and principle, being done, be equal to and replace and improvement etc., all should be included within the protection domain of the present utility model.
Claims (4)
1. capacitance detecting device, wherein testing capacitance is to touch electric capacity on the capacitance plate, this capacitance detecting device comprises: capacitance detection unit, capacitance detection unit is connected with testing capacitance;
It is characterized in that: described capacitance detecting device also comprises:
The peripheral electric capacity of testing capacitance on the capacitance plate;
Voltage on the testing capacitance is fed back to the feedback module of peripheral electric capacity;
The charge control module that control testing capacitance, peripheral electric capacity charge;
The detection control module that the control capacitance detecting unit detects testing capacitance;
The Control and Feedback module is carried out the feedback control module of Voltage Feedback;
Feedback module is connected between testing capacitance and the peripheral electric capacity, and charge control module is connected with testing capacitance, peripheral electric capacity; Detecting control module is connected with capacitance detection unit; Feedback control module is connected with feedback module.
2. capacitance detecting device as claimed in claim 1 is characterized in that: described feedback module is a source follower.
3. capacitance detecting device as claimed in claim 2 is characterized in that: described source follower is an impact damper.
4. capacitance detecting device as claimed in claim 1 is characterized in that: this pick-up unit also comprises: be used to select the mode selection module of stray capacitance mode and general mode, described mode selection module is connected between feedback module and the peripheral electric capacity.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2009202614746U CN201594117U (en) | 2009-12-09 | 2009-12-09 | Capacitance detection device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2009202614746U CN201594117U (en) | 2009-12-09 | 2009-12-09 | Capacitance detection device |
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| Publication Number | Publication Date |
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| CN201594117U true CN201594117U (en) | 2010-09-29 |
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| CN2009202614746U Expired - Lifetime CN201594117U (en) | 2009-12-09 | 2009-12-09 | Capacitance detection device |
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Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103886281A (en) * | 2014-01-14 | 2014-06-25 | 敦泰科技有限公司 | Electric field type fingerprint identification device, state control method thereof and prosthesis identification method |
| CN104569727A (en) * | 2015-01-23 | 2015-04-29 | 珠海隆芯电子科技有限公司 | Non-contact electronic circuit testing device and testing method |
| CN108614161A (en) * | 2018-07-27 | 2018-10-02 | 青岛澳科仪器有限责任公司 | A kind of capacitance measurement system |
| CN110224695A (en) * | 2019-05-22 | 2019-09-10 | 长沙景美集成电路设计有限公司 | A kind of hardware waterproof capacitance touch button circuit |
| CN110823316A (en) * | 2019-10-25 | 2020-02-21 | 德阳市新泰自动化仪表有限公司 | Capacitance signal detection circuit with interference shielding function |
| US10650214B2 (en) | 2018-04-24 | 2020-05-12 | Image Match Design Inc. | Fingerprint sensor and method of fingerprint detection |
| CN113295930A (en) * | 2021-05-31 | 2021-08-24 | 西安电子科技大学 | Micro-watt level micro-capacitance measuring method and circuit |
-
2009
- 2009-12-09 CN CN2009202614746U patent/CN201594117U/en not_active Expired - Lifetime
Cited By (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103886281A (en) * | 2014-01-14 | 2014-06-25 | 敦泰科技有限公司 | Electric field type fingerprint identification device, state control method thereof and prosthesis identification method |
| CN103886281B (en) * | 2014-01-14 | 2017-08-29 | 敦泰电子有限公司 | Electric field type fingerprint identification device, state control method thereof and prosthesis identification method |
| CN104569727A (en) * | 2015-01-23 | 2015-04-29 | 珠海隆芯电子科技有限公司 | Non-contact electronic circuit testing device and testing method |
| US10650214B2 (en) | 2018-04-24 | 2020-05-12 | Image Match Design Inc. | Fingerprint sensor and method of fingerprint detection |
| TWI695310B (en) * | 2018-04-24 | 2020-06-01 | 映智科技股份有限公司 | Fingerprint sensor and method of fingerprint detection |
| CN108614161A (en) * | 2018-07-27 | 2018-10-02 | 青岛澳科仪器有限责任公司 | A kind of capacitance measurement system |
| CN108614161B (en) * | 2018-07-27 | 2024-04-16 | 青岛澳科仪器有限责任公司 | Capacitance measuring system |
| CN110224695A (en) * | 2019-05-22 | 2019-09-10 | 长沙景美集成电路设计有限公司 | A kind of hardware waterproof capacitance touch button circuit |
| CN110823316A (en) * | 2019-10-25 | 2020-02-21 | 德阳市新泰自动化仪表有限公司 | Capacitance signal detection circuit with interference shielding function |
| CN110823316B (en) * | 2019-10-25 | 2021-10-01 | 德阳市新泰自动化仪表有限公司 | Capacitance signal detection circuit with interference shielding function |
| CN113295930A (en) * | 2021-05-31 | 2021-08-24 | 西安电子科技大学 | Micro-watt level micro-capacitance measuring method and circuit |
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