CN106708337B - Capacitance sensing circuit and self-capacitance type touch panel - Google Patents
Capacitance sensing circuit and self-capacitance type touch panel Download PDFInfo
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- CN106708337B CN106708337B CN201510424652.2A CN201510424652A CN106708337B CN 106708337 B CN106708337 B CN 106708337B CN 201510424652 A CN201510424652 A CN 201510424652A CN 106708337 B CN106708337 B CN 106708337B
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F3/00—Input arrangements for transferring data to be processed into a form capable of being handled by the computer; Output arrangements for transferring data from processing unit to output unit, e.g. interface arrangements
- G06F3/01—Input arrangements or combined input and output arrangements for interaction between user and computer
- G06F3/03—Arrangements for converting the position or the displacement of a member into a coded form
- G06F3/041—Digitisers, e.g. for touch screens or touch pads, characterised by the transducing means
- G06F3/044—Digitisers, e.g. for touch screens or touch pads, characterised by the transducing means by capacitive means
- G06F3/0443—Digitisers, e.g. for touch screens or touch pads, characterised by the transducing means by capacitive means using a single layer of sensing electrodes
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- General Engineering & Computer Science (AREA)
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- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Position Input By Displaying (AREA)
Abstract
The invention belongs to touch screen technology fields, provide a kind of capacitance sensing circuit, include multiple channels；And at least one buffer cell, any buffer cell are coupled to a channel to be measured in multiple channels and between another channels；Wherein, the channel to be measured receives input signal and generates output signal, the output signal is transferred to capacitor judgment module by the channel to be measured, the capacitor judgment module judges the capacitance variations in the channel to be measured according to the output signal, the present invention utilizes the unity gain buffer being coupled between channel to be measured and its adjacent channel, to reduce the potential difference between channel to be measured and its adjacent channel, the frequency of input signal is reduced simultaneously, to reduce the crosstalk effect between channel, can reduce correct interchannel it is inconsistent when because of crosstalk capacitance caused by puzzlement, interchannel more can correctly be corrected because inconsistent caused by the factors such as circuit trace or manufacture craft.
Description
Technical field
The invention belongs to touch screen technology fields, more particularly to a kind of capacitance sensing circuit that can eliminate crosstalk between channel
And self-capacitance type touch panel.
Background technique
As science and technology is showing improvement or progress day by day, the operation interface of various electronic products is gradually humanized in recent years.For example, it penetrates
Touch panel, user can directly be operated on the screen with finger or stylus, input information/text/pattern, eliminate the need for key
The trouble of the input equipments such as disk or key.In fact, touch panel is usually by induction panel and to be set to below induction panel
Display composition.Electronic product is the position touched on induction panel according to user, and display is presented at that time
Picture, to judge the meaning of the secondary touching, and execute corresponding operating result.
Existing capacitance touching control technology can be divided into self-tolerant (Self-Capacitance) and mutual capacitance type (Mutual-
Capacitance) two kinds.Compared to mutual-capacitive touch panel, the self-capacitance type touch panel single-layer electrodes knot more simple by processing procedure
Structure is realized, has the advantages that low cost, therefore be widely used in electronic product.Self-capacitance type touch panel can be by sensing circuit
It is formed with multiple channels being arranged in matrix, sensing circuit can sense the electric signal in these channels, and it is converted
For the sensed data value of digital form, to judge touch event.
Specifically, Fig. 1 is please referred to, Fig. 1 is the schematic diagram of a self-capacitance type touch panel 10.Self-capacitance type touch panel 10 is wrapped
Contain vertical channel X1~Xm, horizontal channel Y1~YnAnd sensing circuit 100, vertical channel X1~XmWith horizontal channel Y1~YnWith
Axis interlock (Axis Intersect) mode be arranged in the netted matrix form of grid, each channel can be by multiple capacitor senses
The one-dimentional structure for answering unit to be concatenated into is formed, and the capacitance in each channel is thus detected, and judges whether there is touch-control thing accordingly
Part occurs.As an example it is assumed that preceding vertical channel X occurs for touchingaWith horizontal channel YbCapacitance over the ground is CaAnd Cb, when making
The finger of user touches vertical channel XaWith horizontal channel YbWhen a certain capacitive sensing unit of intersection, i.e. generation capacitance variations
Amount is △ C, if sensing circuit 100 detects vertical channel XaWith horizontal channel YbCapacitance be (Ca+ △ C) and (Cb+△C)
When, i.e. expression finger is touching vertical channel XaWith horizontal channel YbOn intersection.
In the prior art, it due to circuit trace or the mutual tolerance of itself, can be influenced there are crosstalk effect between channel
Judgement to the variation of each channel capacitor, causes to judge by accident.Further, because interchannel is from perhaps screen bulk resistor meeting because of electricity
The factors such as road cabling or manufacture craft and generate inconsistency, and actually need to correct its inconsistency, and crosstalk
The presence of effect can make correction interchannel consistency more difficult, and influence the judgement changed to channel capacitor, or even cause to miss
Sentence.
Summary of the invention
The embodiment of the present invention is designed to provide a kind of capacitance sensing circuit and self-tolerant that can eliminate interchannel crosstalk
Touch panel.
In order to solve the above-mentioned technical problem, the present invention is implemented as follows: a kind of capacitance sensing circuit, includes:
Multiple channels；And
At least one buffer cell, any buffer cell are coupled to a channel to be measured in the multiple channel and another
Between channel；
Wherein, the channel to be measured receives input signal and generates output signal, and the channel to be measured believes the output
It number is transferred to capacitor judgment module, the capacitor judgment module judges that the capacitor of the channel to be measured becomes according to the output signal
Change.
The present invention separately discloses a kind of self-tolerant (Self-Capacitance) touch panel, includes:
Input signal generator；
Capacitor judgment module；
An at least capacitance sensing circuit, any capacitance sensing circuit includes:
Multiple channels；And
At least one buffer cell, any buffer cell are coupled to a channel to be measured in the multiple channel and another
Between channel；
Wherein, the channel to be measured is coupled to the input signal generator to receive input signal, the channel to be measured
It generates output signal and the output signal is transferred to the capacitor judgment module, the capacitor judgment module is according to described defeated
Signal judges the capacitance variations of the channel to be measured out.
In embodiments of the present invention, capacitance sensing circuit is increased using the unit being coupled between channel to be measured and its adjacent channel
Beneficial buffer to reduce the potential difference between channel to be measured and its adjacent channel, while reducing the frequency of input signal, to reduce
Crosstalk effect between channel.Compared to the prior art, the capacitance sensing circuit in the embodiment of the present invention can reduce logical in correction
Because of the puzzlement caused by crosstalk capacitance when inconsistent between road, interchannel more can be correctly corrected because of circuit trace or manufacture craft etc.
It is inconsistent caused by factor.
Detailed description of the invention
Fig. 1 is the schematic diagram of self-capacitance type touch panel.
Fig. 2 is the schematic diagram of one capacitance sensing circuit of the embodiment of the present invention.
Fig. 3 is the firstorder circuit model schematic of capacitance sensing circuit in Fig. 2.
Fig. 4 is the schematic diagram of two capacitance sensing circuit of the embodiment of the present invention.
Fig. 5 is the schematic diagram of three self-capacitance type touch panel of the embodiment of the present invention.
Specific embodiment
In order to make the objectives, technical solutions, and advantages of the present invention clearer, with reference to the accompanying drawings and embodiments, right
The present invention is further elaborated.It should be appreciated that the specific embodiments described herein are merely illustrative of the present invention, and
It is not used in the restriction present invention.
In embodiments of the present invention, capacitance sensing circuit and the applicable electronic product of self-capacitance type touch panel include but not
It is limited to be mobile phone, tablet computer, laptop and electronic reader etc..Below in conjunction with specific embodiment to of the invention
Specific implementation is described in detail.
As shown in Fig. 2, being the schematic diagram of one capacitance sensing circuit 20 of the embodiment of the present invention.For convenience of explanation, capacitor sense
Slowdown monitoring circuit 20 only symbolically includes channel C H_K-1, CH_K, CH_K+1 and buffer BUF1, BUF2, channel C H_K-1, CH_
K, in CH_K+1, each channel is to be concatenated by multiple capacitive sensing units 200, and capacitive sensing unit 200 is with equivalent
Resistance RSWith equivalent capacity CS。
By taking capacitance sensing circuit 20 as an example, channel CH_K is channel to be measured, and in other words, channel CH_K penetrates resistance RTXIt connects
Receive input signal VTXAnd generate output signal VO, according to input signal VTXIt is the capacitor that can determine whether channel CH_K with output signal Vo
Value.However, channel CH_K-1 and CH_K+1 is adjacent and is parallel to channel CH_K, and crosstalk capacitance is formed between channel CH_K
CC, correct each channel it is inconsistent when, crosstalk capacitance CCIt will cause puzzlement.In order to solve crosstalk capacitance CCCaused is tired
It disturbs, the present embodiment couples buffer BUF1, BUF2 between channel to be measured channel adjacent thereto.Specifically, buffer BUF1
It is coupled between channel CH_K and channel CH_K-1, buffer BUF2 is coupled between channel CH_K and channel CH_K+1, buffering
Device BUF1, BUF2 are all unity gain buffer (Unity Gain Buffer), and buffer BUF1, BUF2 are used to make channel CH_
The voltage V of K-1, channel CH_K+1K-1、VK+1Output signal Vo equal to channel CH_K, in this way, crosstalk capacitance CCBoth ends
There is no potential difference, crosstalk capacitance CCCharge will not be stored, crosstalk capacitance C can be eliminatedCCaused crosstalk effect.
On the other hand, in practical applications, crosstalk capacitance CCAlthough both ends without potential difference, however, due to buffer
The bandwidth of BUF1, BUF2 are limited, crosstalk capacitance CCBoth ends (i.e. output signal Vo and voltage VK-1、VK+1Between) there may be phases
Potential difference, and may influence whether output signal Vo.It in this case, can be by reducing input signal VTXFrequency reduce crosstalk
Capacitor CCTo influence caused by output signal Vo.Specifically, Fig. 3 is please referred to, Fig. 3 is the single order electricity of capacitance sensing circuit 20
Road model schematic, channel C H_K-1, CH_K, CH_K+1 are respectively provided with equivalent resistance R_K-1, R_K, R_K+1 and equivalent capacity
C_K-1, C_K, C_K+1, the overall crosstalk capacitor between channel CH_K-1 and channel CH_K can be equivalent to crosstalk capacitance CC_ 1, letter
Overall crosstalk capacitor between road CH_K and channel CH_K+1 can be equivalent to crosstalk capacitance CC_2.In Fig. 3, according to Kirchhoff
Current law (Kirchhoff's Current Law, KCL), the electric current for flowing through node A meet:
(formula 1)；
Wherein, ω system is input signal VTXFrequency, can be input signal VTXDriving frequency.If output signal Vo
With voltage VK-1、VK+1Between phase difference be respectively φ1And φ2, voltage VK-1With voltage VK+1It is represented by Vk-1=VOexp{jω
φ1And Vk+1=VOexp{jωφ2, by aforesaid voltage VK-1With voltage VK+1Expression substitute into formula 1 can obtain
(formula 2)；
By formula 2 it is found that working as phase difference1、φ2When not being 0, crosstalk capacitance CC_1、CC_ 2 still can generate shadow to output signal Vo
It rings, input signal V can be madeTXFrequencies omega be lower than a specific frequency, to inhibit crosstalk capacitance CC_1、CC_ 2 pairs of output signal Vo institutes
The influence of generation.
It can be seen from the above, capacitance sensing circuit utilization is coupled between channel to be measured and its adjacent channel in the embodiment of the present invention
Unity gain buffer, to reduce the potential difference between channel to be measured and its adjacent channel, while reducing the frequency of input signal
Rate, to reduce the crosstalk effect between channel.Compared to the prior art, the capacitance sensing circuit in the embodiment of the present invention can reduce
Correct interchannel it is inconsistent when because of crosstalk capacitance caused by puzzlement, more can correctly correct interchannel because of circuit trace or system
Make inconsistent caused by the factors such as technique.
It is noted that previous embodiment is to illustrate idea of the invention, those skilled in the art works as can evidence
To do different modifications, and it is without being limited thereto.
For example, capacitance sensing circuit 20 only includes 3 channels, in fact, believing included in capacitance sensing circuit
Road number is not limited.Referring to FIG. 4, Fig. 4 is the schematic diagram of two capacitance sensing circuit 40 of the embodiment of the present invention, capacitor sense
Slowdown monitoring circuit 40 includes channel CH_K-L~CH_K+R and multiple unity gain buffer BUF, for the sake of clarity, therefore omits each channel
The circuit model of middle crosstalk capacitance, and channel CH_K-L~CH_K+R is represented with rectangular block, wherein channel CH_K is to believe to side
Road.Buffer BUF can be controlled by the control signal corresponding to each buffer BUF, to control the enabled of each buffer BUF
(Enable) state.Each buffer BUF is coupled to any one non-channel (i.e. channel CH_K-L~CH_K-1 and channel to be measured
One of CH_K+1~CH_K+R channel) and between the channel CH_K of side, so that the output voltage of each non-channel to be measured
With the output signal V to side channel CH_KOIt is equal, also meet requirement of the invention.
In addition, capacitance sensing circuit 40 can be applied in self-capacitance type touch panel.Referring to FIG. 5, Fig. 5 is that the present invention is implemented
The schematic diagram of three self-capacitance type touch panel 50 of example.Self-capacitance type touch panel 50 includes input signal generator 500, capacitor judgement
Module 502 and capacitance sensing circuit 52_1~52_N, input signal generator 500 are used to generate input signal VTX, capacitor judgement
Module 502 is used to receive output signal V caused by capacitance sensing circuit 52_1~52_NO_ 1~VO_ N, to judge capacitance sensing
To the capacitance of wing passage, circuit structure and the capacitance sensing electricity of capacitance sensing circuit 52_1~52_N in circuit 52_1~52_N
Road 40, details are not described herein.
In conclusion the capacitance sensing circuit of the embodiment of the present invention eliminates self-tolerant touch surface using unity gain buffer
Potential difference in plate between channel channel adjacent thereto to be measured, while the frequency of input signal is reduced, to reduce between channel
Crosstalk effect, can reduce correct interchannel it is inconsistent when because of crosstalk capacitance caused by puzzlement, and then correctly correct channel
Between because inconsistent caused by the factors such as circuit trace or manufacture craft.
The foregoing is merely illustrative of the preferred embodiments of the present invention, is not intended to limit the invention, all in essence of the invention
Made any modifications, equivalent replacements, and improvements etc., should all be included in the protection scope of the present invention within mind and principle.
Claims (6)
1. a kind of capacitance sensing circuit, which is characterized in that include:
Multiple channels；And
At least two buffer cells, wherein at least a buffer cell are coupled to the channel to be measured and one in the multiple channel
Between non-channel to be measured, another buffer cell is coupled between the channel to be measured and another non-channel to be measured, described to be measured logical
Road is used to receive input signal by resistance and generates output signal, and the input terminal electric current in the channel to be measured meets:
Wherein, CC_1 is the voltage V of the output signal Vo and the non-channel to be measuredK-1Between crosstalk capacitance, CC_2 be described
The voltage V of output signal Vo and another non-channel to be measuredK+1Between crosstalk capacitance, RTXFor resistance, R_K is channel to be measured
Equivalent resistance, C_K be channel to be measured equivalent capacity, ω be input signal VTXFrequency, Vo is output signal；
The input signal has specific frequency, and the specific frequency believes the output less than a threshold value, the channel to be measured
It number is transferred to capacitor judgment module, the capacitor judgment module judges that the capacitor in the channel to be measured becomes according to the output signal
Change.
2. capacitance sensing circuit as described in claim 1, which is characterized in that the buffer cell is controlled by control signal, institute
State the enabled state that control signal is used to control the buffer cell.
3. capacitance sensing circuit as described in claim 1, which is characterized in that the buffer cell has unit gain (Unity
Gain)。
4. a kind of self-tolerant (Self-Capacitance) touch panel, which is characterized in that include:
Input signal generator；
Capacitor judgment module；
An at least capacitance sensing circuit, any capacitance sensing circuit includes:
Multiple channels；And
At least two buffer cells, wherein at least a buffer cell are coupled to the channel to be measured and one in the multiple channel
Between non-channel to be measured, another buffer cell is coupled between the channel to be measured and another non-channel to be measured, described to be measured logical
Road is coupled to the input signal generator to receive input signal, and the channel to be measured generates output signal, described to be measured logical
The input terminal electric current in road meets:
Wherein, CC_1 is the voltage V of the output signal Vo and the non-channel to be measuredK-1Between crosstalk capacitance, CC_2 be described
The voltage V of output signal Vo and another non-channel to be measuredK+1Between crosstalk capacitance, RTXFor resistance, R_K is channel to be measured
Equivalent resistance, C_K be channel to be measured equivalent capacity, ω be input signal VTXFrequency, Vo is output signal；
The input signal has specific frequency, and the specific frequency believes the output less than a threshold value, the channel to be measured
Number it is transferred to the capacitor judgment module, the capacitor judgment module judges the electricity in the channel to be measured according to the output signal
Hold variation.
5. touch panel as claimed in claim 4, which is characterized in that the buffer cell is controlled by control signal, the control
Signal processed is used to control the enabled state of the buffer cell.
6. touch panel as claimed in claim 4, which is characterized in that the buffer cell has unit gain (Unity
Gain)。
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201510424652.2A CN106708337B (en) | 2015-07-17 | 2015-07-17 | Capacitance sensing circuit and self-capacitance type touch panel |
| PCT/CN2015/094467 WO2017012221A1 (en) | 2015-07-17 | 2015-11-12 | Capacitance sensing circuit and self-capacitive touch-control panel |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201510424652.2A CN106708337B (en) | 2015-07-17 | 2015-07-17 | Capacitance sensing circuit and self-capacitance type touch panel |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN106708337A CN106708337A (en) | 2017-05-24 |
| CN106708337B true CN106708337B (en) | 2019-11-15 |
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| CN201510424652.2A Active CN106708337B (en) | 2015-07-17 | 2015-07-17 | Capacitance sensing circuit and self-capacitance type touch panel |
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|---|---|
| CN (1) | CN106708337B (en) |
| WO (1) | WO2017012221A1 (en) |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102193032A (en) * | 2010-03-08 | 2011-09-21 | 上海海栎创微电子有限公司 | Self-capacitance change measuring circuit with high precision and high stability |
| CN102799325A (en) * | 2012-06-21 | 2012-11-28 | 敦泰科技有限公司 | Method, device and system for detecting self-capacitance touch screen |
| CN102799322A (en) * | 2011-05-27 | 2012-11-28 | 晨星软件研发(深圳)有限公司 | Capacitive sensing device and control method |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101349957B (en) * | 2008-07-29 | 2010-07-21 | 友达光电股份有限公司 | Data reading controller thereof |
| CN103902116B (en) * | 2012-12-30 | 2017-04-12 | 比亚迪股份有限公司 | anti-interference method and device for capacitance detection |
-
2015
- 2015-07-17 CN CN201510424652.2A patent/CN106708337B/en active Active
- 2015-11-12 WO PCT/CN2015/094467 patent/WO2017012221A1/en active Application Filing
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102193032A (en) * | 2010-03-08 | 2011-09-21 | 上海海栎创微电子有限公司 | Self-capacitance change measuring circuit with high precision and high stability |
| CN102799322A (en) * | 2011-05-27 | 2012-11-28 | 晨星软件研发(深圳)有限公司 | Capacitive sensing device and control method |
| CN102799325A (en) * | 2012-06-21 | 2012-11-28 | 敦泰科技有限公司 | Method, device and system for detecting self-capacitance touch screen |
Also Published As
| Publication number | Publication date |
|---|---|
| WO2017012221A1 (en) | 2017-01-26 |
| CN106708337A (en) | 2017-05-24 |
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