CN102023766B - Capacitor touch control panel detection circuit and method - Google Patents
Capacitor touch control panel detection circuit and method Download PDFInfo
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- CN102023766B CN102023766B CN200910175944.1A CN200910175944A CN102023766B CN 102023766 B CN102023766 B CN 102023766B CN 200910175944 A CN200910175944 A CN 200910175944A CN 102023766 B CN102023766 B CN 102023766B
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- voltage
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- sampling voltage
- numerical code
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Abstract
The invention discloses a capacitor touch control panel detection circuit, which is characterized by comprising a sampling and holding circuit, a successive approximation register (SAR) and control circuit, a digital-to-analog conversion circuit, a multiplexer and a comparator, wherein the sampling and holding circuit samples a path line voltage of a path line and generates a sampling voltage; when the sampling voltage is lower than a threshold voltage, the SAR and control circuit outputs an ending signal and stops conversion; and when the sampling voltage is higher than a threshold voltage, the SAR and control circuit performs the continuous approximation of the sampling voltage to generate the numerical code of the sampling voltage. The capacitor touch control panel detection circuit and the capacitor touch control panel detection method have the advantages of pre-filtering useless path lines, reducing calculation amount of a detection circuit, improving frame rate, reducing power consumption of the detection circuit and improving the efficiency of the capacitor touch control panel.
Description
Technical field
The present invention relates to a kind of capacitive touch control plate, specifically, is a kind of testing circuit and method of capacitive touch control plate.
Background technology
On the capacitive touch control plate of two dimension formula, be provided with many directions X traces and Y-direction trace, described directions X trace and a plurality of inductors of the interlaced composition of Y-direction trace, when user is with electric conductivity object, for example point, while approaching described inductor, finger will make to be connected the capacitance increase of the trace of described inductor with the coupling capacitance between described inductor, testing circuit is just by the capacitance variation detecting on described trace, orient the position of finger, and convert the variation of described position to information, offer main frame and carry out corresponding operating.
Fig. 1 is for pointing the schematic diagram that trace is caused to capacitance variation, and horizontal ordinate represents horizontal trace Y1, and trace X1～X8 and trace Y1 are staggered, the capacitance variation that curve 10 represents on trace Y1.When finger approaches the intersection point of trace Y1 and trace X4, X5, uninfluenced away from trace X1, the X2 of finger and the capacitance of X7, X8, lower than threshold value C
tH, approach the trace X3 of finger and the rising of the capacitance of X6, a little more than threshold value C
tH, the capacitance of the trace X5 that distance finger is nearer is higher, the trace X4 at place, finger position place and capacitance be the peak value of curve 10, therefore, by after trace X4 and Y1 combination, can judge to point and be positioned at (X4, Y1).In Fig. 1, the capacitance of trace X1, X2 and X7, X8 is not subject to finger impact, and the value when detecting approaches zero, in follow-up conversion and computing judgement, is useless (useless).
Capacitance cannot direct-detection in side circuit, therefore the detection method of capacitive touch control plate is one by one to every trace charging, detect change in voltage on every trace to obtain the information of capacitance variation, changed, Fig. 2 is known Continuous Approximation buffer (Successive Approximation Register again; SAR) schematic diagram of analog-to-digital circuit (ADC).The trace voltages Vin of sampling and holding circuit 12 sampling one traces, produces sampling voltage V
sgive comparer 14, meanwhile, SAR and control circuit 18 output Continuous Approximation numerical code D
0～D
n-1, via numeral, turn analog converter 16 and coordinate reference voltage Vref conversion to produce voltage V
d, with sampling voltage V
srelatively produce comparative result to SAR and control circuit 18, SAR and control circuit 18 are adjusted Continuous Approximation numerical code D according to comparative result again
0～D
n-1, the voltage V that conversion makes new advances again
dwith sampling voltage V
srelatively, progressively approach sampling voltage V
sand generation numerical code, described numerical code offers firmware, inserts the value of described trace.
Known detection method is one by one to every trace charging on capacitive touch control plate, detect the trace voltages of each trace and carry out aforesaid Continuous Approximation and change the numerical code that produces described trace and offer firmware, jump to again next trace, carry out identical step and obtain one by one the numerical code of each trace, conversion produces a frame (frame) information and orients finger position, wherein, after its trace voltages of the unconverted trace of capacitance converts numerical code to, there is no function.
Therefore known detection method exists the useless trace of above-mentioned detection, increases testing circuit power consumption and low all inconvenience and the problem of Trackpad usefulness.
Summary of the invention
Object of the present invention, is to propose a kind of testing circuit of capacitive touch control plate.
Another object of the present invention, is to propose a kind of detection method of capacitive touch control plate.
For achieving the above object, technical solution of the present invention is:
A testing circuit for capacitive touch control plate, is characterized in that comprising:
Sampling and holding circuit, the trace voltages of sampling one trace produces sampling voltage;
SAR and control circuit, provide threshold numerical code and Continuous Approximation numerical code, and pre-converted signal is provided when starting to change described sampling voltage;
Numeral turns mimic channel, according to described threshold numerical code or the conversion of described Continuous Approximation numerical code, produces threshold voltage or comparative voltage;
Multiplexer, be connected to described SAR and control circuit and described numeral turns between mimic channel, according to described pre-converted signal, described threshold numerical code is offered to described numeral and turns mimic channel, other time described Continuous Approximation numerical code offered to described numeral turn mimic channel; And
Comparer, connects described numeral and turns mimic channel and described sampling and holding circuit, described sampling voltage is compared with described threshold voltage or described comparative voltage, and export comparative result to described SAR and control circuit;
Wherein, if described sampling voltage is lower than described threshold voltage, described SAR and control circuit output are ended signal and are stopped conversion, if described sampling voltage is higher than described threshold voltage, described SAR and control circuit are carried out Continuous Approximation to produce the numerical code of described sampling voltage to described sampling voltage.
A detection method for capacitive touch control plate, is characterized in that comprising the following steps:
(a) trace voltages of sampling one trace produces sampling voltage;
(b) more described sampling voltage and threshold voltage;
(c) if described trace voltages is less than described threshold voltage, end the conversion of described trace voltages; And
(d), if described trace voltages is greater than described threshold voltage, described trace voltages is carried out to Continuous Approximation to produce the numerical code of described trace voltages.
The detection method of capacitive touch control plate of the present invention can also be further achieved by the following technical measures.
Aforesaid detection method, wherein more comprises that conversion produces described threshold voltage according to threshold numerical code.
Aforesaid detection method, wherein said step (c) comprising:
If described trace voltages is less than described threshold voltage, produces and end signal; And
According to described termination signal, end the conversion of described trace voltages, skip described trace.
Aforesaid detection method, wherein said step (c) comprising:
If described trace voltages is less than described threshold voltage, produces and end signal; And
According to described termination signal, end the conversion of described trace voltages, it is zero that the value of described trace is filled out.
Adopt after technique scheme, testing circuit and the method for capacitive touch control plate of the present invention have the following advantages:
1. the useless trace of filtering in advance.
2. reduce the operand of testing circuit, promote the power consumption of frame speed (frame rate) or minimizing testing circuit.
3. promote the usefulness of capacitive touch control plate.
Accompanying drawing explanation
Fig. 1 is for pointing the signal that trace capacitances value is caused to variation
Fig. 2 is the schematic diagram of known SAR ADC;
Fig. 3 is schematic diagram according to an embodiment of the invention; And
Fig. 4 is the process flow diagram of the embodiment of Fig. 3.
In figure, 10, curve 12, sampling and holding circuit 14, comparer 16, numeral turn that mimic channel 18, SAR and control circuit 22, sampling and holding circuit 24, comparer 26, numeral turn mimic channel 28, multiplexer 30, SAR and control circuit 50, start 52, V relatively
sand V
tH54, V
s< V
tHdo are 56,1-bit SAR analog-to-digital conversion 58, present bit last position? 60, carry out next bit computing 62, interrupt current conversion 64, finish conversion.
Embodiment
Below in conjunction with embodiment and accompanying drawing thereof, the present invention is illustrated further.
Now refer to Fig. 3, Fig. 3 is schematic diagram according to an embodiment of the invention.As shown in the figure, described SAR and control circuit 30 are except providing Continuous Approximation numerical code D
0～D
n-1outside, threshold numerical code T is also provided
0～T
n-1, multiplexer 28 is multiplexers of an alternative, when receiving the pre-converted order of SAR and control circuit 30 by threshold numerical code T
0～T
n-1offer numeral and turn mimic channel 26, other time by Continuous Approximation numerical code D
0～D
n-1offer numeral and turn mimic channel 26.In other embodiments, mode that can also usage count, by threshold numerical code T
0～T
n-1offer numeral and turn after mimic channel 26, in ensuing n, circulate Continuous Approximation numerical code D
0～D
n-1offer numeral and turn mimic channel 26.Comparer 24 turns numeral the threshold voltage V of mimic channel 26 conversion generations
tHor voltage V
dsampling voltage V with sampling and holding circuit 22 sampling generations
scompare, output comparative result is to SAR and control circuit 30.In the present embodiment, SAR and control circuit 30 are when starting a trace voltages to change, and output pre-converted signal makes multiplexer 28 by threshold numerical code T
0～T
n-1offer numeral and turn analog converter 26, numeral turns analog converter 26 according to threshold numerical code T
0～T
n-1conversion produces threshold voltage V
tHif, sampling voltage V
slower than threshold voltage V
tH, SAR and control circuit 30 are just exported and are ended signal Abort, stop the subsequent conversion action to described trace voltages, and jump to next trace; If sampling voltage V
shigher than threshold voltage V
tH, multiplexer 28 just continues Continuous Approximation numerical code D
0～D
n-1offer numeral and turn mimic channel 26, described trace voltages is carried out to Continuous Approximation and to produce numerical code, for firmware, insert the value of described trace.Threshold numerical code T
0～T
n-1that trace fundamental voltage when without finger contact determines.
Fig. 4 is the process flow diagram of the embodiment of Fig. 3, after starting 50, in step 52 by sampling voltage V
swith threshold voltage V
tHcompare, judgement sampling voltage V
swhether be less than threshold voltage V
tH54, if so, interrupt current conversion 62, jump to and finish conversion 64; If not, enter step 56 and carry out the SAR ADC conversion of, and judge whether be last position 58, if so, finish to change 64, if not, carry out next bit computing 60, get back to step 56 current.
In the aforementioned embodiment, send and end signal or interrupt after current conversion, the computing that can skip described trace by software or firmware, or the value of described trace is filled out is zero, the computing that just can directly omit thus useless trace.In other embodiments, can realize the pre-filtering level (pre-filtering stage) that the present invention proposes with hardware, software or firmware.
In side circuit, testing circuit often detects twice, four times, six times even after eight times to same trace, be switched to again next trace and do same detection, the capacitive touch control plate with N bar directions X trace and N bar Y-direction trace of take is example, form a frame and need to scan N+N bar trace, and every trace need detect M time, therefore a frame needs computing M*2N time.It is useless that the detection method that the present invention proposes can just be judged described trace when detecting a trace for the first time, not only omit follow-up data conversion, also save to described useless trace repeat scan, effectively reduce operand, thereby promote frame speed or reduce power consumption.
Above embodiment is used for illustrative purposes only, but not limitation of the present invention, person skilled in the relevant technique, without departing from the spirit and scope of the present invention, can also make various conversion or variation.Therefore, all technical schemes that are equal to also should belong to category of the present invention, should be limited by each claim.
Claims (4)
1. a testing circuit for capacitive touch control plate, is characterized in that comprising:
Sampling and holding circuit, the trace voltages of sampling one trace produces sampling voltage;
Continuous Approximation buffer and control circuit, provide threshold numerical code and Continuous Approximation numerical code, and pre-converted signal is provided when starting to change described sampling voltage;
Numeral turns mimic channel, according to described threshold numerical code or the conversion of described Continuous Approximation numerical code, produces threshold voltage or comparative voltage;
Multiplexer, being connected to described Continuous Approximation buffer and control circuit and described numeral turns between mimic channel, according to described pre-converted signal, described threshold numerical code is offered to described numeral and turns mimic channel, other time described Continuous Approximation numerical code offered to described numeral turn mimic channel; And
Comparer, connects described numeral and turns mimic channel and described sampling and holding circuit, described sampling voltage is compared with described threshold voltage or described comparative voltage, and export comparative result to described Continuous Approximation buffer and control circuit;
Wherein, if described sampling voltage is lower than described threshold voltage, described Continuous Approximation buffer and control circuit output are ended signal and are stopped conversion, and jump to next trace, if described sampling voltage is higher than described threshold voltage, described Continuous Approximation buffer and control circuit are carried out Continuous Approximation to produce the numerical code of described sampling voltage to described sampling voltage.
2. a detection method for capacitive touch control plate, is characterized in that comprising the following steps:
(a) trace voltages of sampling one trace produces sampling voltage;
(b) a threshold numerical code is provided to a numeral and turn mimic channel, to produce a threshold voltage;
(c) more described sampling voltage and described threshold voltage;
(d) if described sampling voltage is less than described threshold voltage, end the conversion of described sampling voltage, and jump to next trace; And
(e) if described sampling voltage is greater than described threshold voltage, a continuously nearly numerical code is offered to this numeral and turn mimic channel, described sampling voltage is carried out to Continuous Approximation to produce the numerical code of described sampling voltage.
3. detection method as claimed in claim 2, is characterized in that, described step (d) comprising:
If described sampling voltage is less than described threshold voltage, produces and end signal; And
According to described termination signal, end the conversion of described sampling voltage, skip described trace.
4. detection method as claimed in claim 2, is characterized in that, described step (d) comprising:
If described sampling voltage is less than described threshold voltage, produces and end signal; And
According to described termination signal, end the conversion of described sampling voltage, it is zero that the value of described trace is filled out.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN200910175944.1A CN102023766B (en) | 2009-09-14 | 2009-09-14 | Capacitor touch control panel detection circuit and method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN200910175944.1A CN102023766B (en) | 2009-09-14 | 2009-09-14 | Capacitor touch control panel detection circuit and method |
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| Publication Number | Publication Date |
|---|---|
| CN102023766A CN102023766A (en) | 2011-04-20 |
| CN102023766B true CN102023766B (en) | 2014-12-03 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN200910175944.1A Expired - Fee Related CN102023766B (en) | 2009-09-14 | 2009-09-14 | Capacitor touch control panel detection circuit and method |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN111477114B (en) * | 2020-05-25 | 2022-05-10 | 维沃移动通信有限公司 | Foldable electronic device |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4679028A (en) * | 1986-03-31 | 1987-07-07 | Motorola Inc. | Fault detection algorithm for successive-approximation A/D converters |
| US6738048B1 (en) * | 1999-10-29 | 2004-05-18 | Texas Instruments Incorporated | Touch screen controller |
| CN1981442A (en) * | 2004-03-31 | 2007-06-13 | 芯科实验室有限公司 | Method and apparatus for subclocking a sar analog-to-digital converter |
| CN101526871A (en) * | 2008-03-04 | 2009-09-09 | 禾瑞亚科技股份有限公司 | Sensing device and method for capacitance type touch control panel |
-
2009
- 2009-09-14 CN CN200910175944.1A patent/CN102023766B/en not_active Expired - Fee Related
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4679028A (en) * | 1986-03-31 | 1987-07-07 | Motorola Inc. | Fault detection algorithm for successive-approximation A/D converters |
| US6738048B1 (en) * | 1999-10-29 | 2004-05-18 | Texas Instruments Incorporated | Touch screen controller |
| CN1981442A (en) * | 2004-03-31 | 2007-06-13 | 芯科实验室有限公司 | Method and apparatus for subclocking a sar analog-to-digital converter |
| CN101526871A (en) * | 2008-03-04 | 2009-09-09 | 禾瑞亚科技股份有限公司 | Sensing device and method for capacitance type touch control panel |
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| CN102023766A (en) | 2011-04-20 |
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