CN103837748A - Touch control system and electric capacity detection device thereof - Google Patents

Abstract

The invention relates to a touch control system and an electric capacity detection device thereof. The detection device provided by the invention is used for detecting N capacitors in a touch control panel. The detection device generates N different input signals and provides the ith input signal of the input signals to the ith capacitor. The N input signals are respectively corresponding to a post-delay sequence of a maximum-length sequence or corresponding to the maximum-length sequence. The detection device totals N response signals generated after the N input signals are provided to the N capacitors so that a totaling signal is generated. Then the totaling signal is multiplied by the ith input signal and integrated so that an ith signal after integration is generated. Respective electric capacity of the N capacitors is estimated according to the N signals after integration.

Description

Touch-control system and electric capacity pick-up unit thereof

Technical field

The present invention is relevant to touch-control system, and especially relevant to the technology of the electric capacity in order to measure capacitance type touch-control panel.

Background technology

Along with science and technology is showing improvement or progress day by day, all more and more hommizations of the operation interface of various electronic products in recent years.For example, see through Touch Screen, user can directly make program, input message/word/pattern with finger or pointer in on-screen options, saves the trouble of input medias such as using keyboard or button.In fact, Touch Screen is normally made up of an induction panel and the display that is arranged at induction panel rear.The picture that the position that electronic installation can be touched according to user on induction panel and at that time display present, judges the meaning of this touching and carries out corresponding operating result.

Existing touch technology is roughly divided into resistance-type, condenser type, induction, ultrasonic formula and several classes of optical profile type.Capacitance type touch-control panel comprises multiple electrodes, and user's touching can change the electric capacity of electrode.Whether change by the electric capacity that measures each electrode, just can judge the position of touch points.Fig. 1 has illustrated a typical electric capacity testing circuit, and capacitor C x wherein represents tested electric capacity.The relation of input voltage Vi, reference voltage Vpp and output voltage V o can be expressed as follows: $\frac{\mathrm{Vo}-\mathrm{Vpp}}{\frac{1}{\mathrm{SCfb}}}=\frac{\mathrm{Vpp}-\mathrm{Vi}}{\frac{1}{\mathrm{SCx}}}.$ (formula one)

Due to input voltage Vi, reference voltage Vpp with feedback the electric capacity of capacitor C fb and be all knownly, can calculate the electric capacity of tested capacitor C x according to output voltage V o.For example, if be set as ground voltage with reference to voltage Vpp, between the absolute value of output voltage V o and tested capacitor C x, can there is specific proportional relation.

The electrod-array being made up of multiple rhombus electrodes presenting taking Fig. 2 is example, sees through the switching of multiplexer, and electrode E11 ~ E75 can be sequentially connected to the operational amplifier 12 in testing circuit 100, as tested capacitor C x.Easy speech, testing circuit 100 can be used to measure one by one the electric capacity of each electrode.The shortcoming of this way is, testing circuit 100 can only be measured the electric capacity of an electrode at every turn, and speed is slower, is especially not suitable for the application that touch-control area is larger.

Fig. 3 has illustrated a kind of testing circuit 300 that can simultaneously measure multiple electric capacitys in prior art.Situation taking tested electric capacity quantity as five, as example, as shown in Figure 3, provides different to the input voltage of tested capacitor C 1 ~ C5.Operational amplifier 32 forms one with back coupling capacitor C fb equivalence and adds way circuit, and it adds overall result and comprises following five items: $\frac{\cos (2\mathrm{\&pi;}*M*t)}{\mathrm{Cfb}}*C1,\frac{\cos (2\mathrm{\&pi;}*2M*t)}{\mathrm{Cfb}}*\mathrm{<figure-callout\; id="2"\; label="C"\; filenames="HDA00002457315500021.png"\; state="\{\{state\}\}">C</figure-callout>}2,\frac{\cos (2\mathrm{\&pi;}*3M*t)}{\mathrm{Cfb}}*C3,$ $\frac{\cos (2\mathrm{\&pi;}*4M*t)}{\mathrm{Cfb}}*C4,\frac{\cos (2\mathrm{\&pi;}*5M*t)}{\mathrm{Cfb}}*C5,$ Wherein M represents a predeterminated frequency.

Analogue-to-digital converters (ADC) 34 are responsible for the output voltage of operational amplifier 32 (that is the above-mentioned overall result that adds) to be converted to digital signal.Accordingly, follow-up multiplier 36A ~ 36E and integrator 38A ~ 38E are all digital circuit.The integrating range length of integrator 38A ~ 38E is all (1/M).With regard to the path at multiplier 36A sum-product intergrator 38A place, after process integrator 38A, only can leave in theory the originally item corresponding to frequency M, the inferior integral result of other four items is zero.Therefore, the output signal of integrator 38A only can be relevant to the electric capacity of capacitor C 1, has nothing to do in the electric capacity of capacitor C 2 ~ C5.Just can extrapolate the electric capacity of capacitor C 1 according to the output signal of integrator 38A.Similarly, with regard to the path at multiplier 36B sum-product intergrator 38B place, after integrator 38B, only can leave the originally item corresponding to frequency 2M, the output signal of integrator 38B is only relevant to the electric capacity of capacitor C 2.The rest may be inferred, according to the output signal of integrator 38B ~ 38E, can extrapolate respectively the electric capacity of capacitor C 2 ~ C5.

One of shortcoming of testing circuit 300 is, provide to five string ripple signals of tested capacitor C 1 ~ C5 be likely in-phase signal, thereby there is a peak value in adding of making to produce in operational amplifier 32 output terminals in overall result.Will be understood that, the more, the variation range of the output signal voltage of operational amplifier 32 is just larger for tested electric capacity quantity, and its peak value also can be along with rising to average ratio (peak-to-average-ratio, PAPR).Thus, just must adopt the wider operational amplifier 32 in linear operation interval.In addition,, under the fixing condition of resolution, also must adopt the wider analogue-to-digital converters 34 of input voltage range.Above two problems all can cause the increase of power consumption and hardware cost.

Summary of the invention

For addressing the above problem, the present invention proposes new electric capacity pick-up unit and detection method.By utilizing the signal producing according to maximal-length sequence (maximum length sequence) as the voltage providing to tested electric capacity, can reach according to pick-up unit of the present invention and detection method the effect that simultaneously detects multiple capacitances, and can provide the signal noise that is better than prior art than performance.The peak value that must bear according to the circuit in pick-up unit of the present invention in addition, is low compared with prior art to average ratio.

A specific embodiment according to the present invention is a kind of pick-up unit.This pick-up unit is in order to detect N electric capacity in a contact panel, and N is greater than 1 integer.This pick-up unit comprises a voltage generator, and adds up module, a N multiplier, a N integrator and an estimation module.This voltage generator is in order to produce N input signal and an i input signal is wherein provided to the i electric capacity in this N electric capacity.This N input signal different and correspond respectively to one of a maximal-length sequence and postpone after sequence or this maximal-length sequence itself.I is the integer index of scope between 1 to N.This totalling module provides this N input signal to N the reaction signal producing after this N electric capacity in order to add up, and adds resultant signal to produce one.An i multiplier in N multiplier in order to by this totalling signal times with this i input signal, with signal after producing an i and multiplying each other.An i integrator in N integrator is in order to signal integration after this i is multiplied each other, to produce signal after an i integration.Estimation module is in order to according to this N of Signal estimation electric capacity electric capacity separately after this N integration.

Another specific embodiment according to the present invention is a kind of capacitance touch control system, wherein comprises a contact panel, a voltage generator, a totalling module, a N multiplier, a N integrator and an estimation module.This contact panel comprises N electric capacity, and N is greater than 1 integer.This voltage generator is in order to produce N input signal and an i input signal is wherein provided to the i electric capacity in this N electric capacity.This N input signal different and correspond respectively to one of a maximal-length sequence and postpone after sequence or this maximal-length sequence itself.I is the integer index of scope between 1 to N.This totalling module provides this N input signal to N the reaction signal producing after this N electric capacity in order to add up, and adds resultant signal to produce one.An i multiplier in N multiplier in order to by this totalling signal times with this i input signal, with signal after producing an i and multiplying each other.An i integrator in N integrator is in order to signal integration after this i is multiplied each other, to produce signal after an i integration.Estimation module is in order to according to this N of Signal estimation electric capacity electric capacity separately after this N integration.

Another specific embodiment according to the present invention is a kind of detection method, in order to detect N electric capacity in a contact panel.N is greater than 1 integer.First this detection method carries out a generation step, produces N input signal and an i input signal is wherein provided to the i electric capacity in this N electric capacity.This N input signal different and correspond respectively to one of a maximal-length sequence and postpone after sequence or this maximal-length sequence itself.I is the integer index of scope between 1 to N.Then, this detection method is carried out one and is added up step, adds up this N input signal is provided to N the reaction signal producing after this N electric capacity, adds resultant signal to produce one.This adds resultant signal and is multiplied by this i input signal, with signal after producing an i and multiplying each other.After this i multiplies each other, signal is integrated, to produce signal after an i integration.Subsequently, this detection method is carried out an estimating step, according to this N of Signal estimation electric capacity electric capacity separately after this N integration.

Can be further understood by following detailed description and accompanying drawings about the advantages and spirit of the present invention.

Brief description of the drawings

Fig. 1 has illustrated a typical electric capacity testing circuit.

Fig. 2 has illustrated the electrod-array being made up of multiple rhombus electrodes.

Fig. 3 has illustrated a kind of testing circuit that can simultaneously measure multiple electric capacitys in prior art.

Fig. 4 is according to the functional block diagram of the electric capacity pick-up unit in one embodiment of the invention.

Fig. 5 (A) ~ Fig. 5 (C) is according to input signal example of the present invention.

Fig. 6 is a kind of internal circuit example according to estimation module of the present invention.

Fig. 7 further comprises the example of wave filter according to pick-up unit of the present invention.

Fig. 8 is according to the process flow diagram of electric capacity detection method of the present invention.

Main element symbol description

100: electric capacity testing circuit Cx, C0 ~ C14: tested electric capacity

Cfb: back coupling electric capacity 12,32,421: operational amplifier

E11 ~ E75: electrode 34,43: analogue-to-digital converters

36A ~ 36E, 44,45A ~ 45O: multiplier

38A ~ 38E, 46A ~ 46O: integrator

400: electric capacity testing circuit 41: voltage generator

42: add up module 47: estimation module

48A ~ 48O: low-pass filter S81 ~ S85: process step

Embodiment

Be the electric capacity pick-up unit in order to matching with capacitive contact panel according to one embodiment of the invention, its functional block diagram as shown in Figure 4.Pick-up unit 400 comprises voltage generator 41, adds up module 42, analogue-to-digital converters 43, multiplier 44, multiplier 45A ~ 45O, integrator 46A ~ 46O and estimation module 47.Below explanation is first to utilize situation that pick-up unit 400 detects 15 tested electric capacity as example.Should be noted that, the quantity of tested electric capacity is not limited with 15, and multiplier and integrator quantity in pick-up unit 400 can, according to the quantity adjustment of tested electric capacity, be detailed later.

In this embodiment, voltage generator 41 produces 15 input signal V0 ~ V14 altogether, and these input signals are provided respectively to tested capacitor C 0 ~ C14.Input signal V0 ~ V14 is different, and corresponds respectively to sequence or this maximal-length sequence itself after the delay of a maximal-length sequence (maximum length sequence).The characteristic of maximal-length sequence signal is, by 0, with 1 replacement, 1 replaces with-1, and the totalling of a periodic quantity is combined into-1; To select sequence and make auto-correlation computation, can obtain its discrete value is all+1, and its totalling is combined into the length value of selected sequence; Original selected sequence is moved down after a numeral and can obtain it at the auto-correlation function value of a Cycle Length to add total value be-1; Sequentially move down if continue again a numeral in a Cycle Length, do that auto-correlation function value calculates also can be for-1.Known to persond having ordinary knowledge in the technical field of the present invention, a maximal-length sequence comprises M bit altogether, and M equals 2 ⁿ-1, n is greater than 1 integer.That is to say, total number of cells of a maximal-length sequence may be 3,7,15 ...Fig. 5 (A) is an example of input signal V0 ~ V14, and the maximal-length sequence in this example is this maximal-length sequence that total number of cells equals 15, and 15 bits are wherein: [000111101011001].Because maximal-length sequence has the characteristic of circulation (cyclic), the sequence that this maximal-length sequence is postponed to produce after a bit is: [100011110101100].Can be found out by Fig. 5 (A), input signal V0 (represents bit 0 with negative voltage corresponding to this maximal-length sequence itself, represent bit 1 with positive voltage), input signal V1 is corresponding to this maximal-length sequence being postponed to sequence after delay that a bit produces, and input signal V2 ~ V14 corresponds respectively to previous sequence to postpone sequence after delay that a bit produces again.

In practice, this maximal-length sequence and postpone after sequence can be by burning in advance in ROM, or produce circuit with maximal-length sequence, Dynamic Generation sequential value, voltage supplied generator 41 is as the foundation that produces input signal V0 ~ V14.As the example that Fig. 5 (B) and Fig. 5 (C) are presented, be not limited to square wave corresponding to the pulse of each bit, also can be triangular wave, semicircle ripple or other waveforms.

Voltage generator 41 provides input signal V0 ~ V14 to tested capacitor C 0 ~ C14 separately, can in subsequent conditioning circuit, cause respectively different reaction signals.Add up module 42 and be responsible for adding up these reaction signals, add resultant signal Vo to produce.In this embodiment, add up module 42 and comprise operational amplifier 421 and feedback capacitor C fb.Add and in resultant signal Vo, comprise 15 separately corresponding to the item of the tested electric capacity of difference:

$\mathrm{Vo}=\frac{V_0}{{\mathrm{<figure-callout\; id="0"\; label="C\; fb\; C"\; filenames="HDA00002457315500021.png"\; state="\{\{state\}\}">C</figure-callout>}}_{\mathrm{fb}}}{C}_{}{}_0+\frac{V_1}{C_{\mathrm{fb}}}{C}_1+\frac{V_2}{{\mathrm{<figure-callout\; id="2"\; label="C\; fb\; C"\; filenames="HDA00002457315500021.png"\; state="\{\{state\}\}">C</figure-callout>}}_{\mathrm{fb}}}{C}_{}{}_2+...+\frac{V_{14}}{C_{\mathrm{fb}}}{C}_{14},$ (formula three)

Through after analogue-to-digital converters 43, add resultant signal Vo and be converted into digital signal A[n]:

$A\left[n\right]=\frac{V_0\left[n\right]}{{\mathrm{<figure-callout\; id="0"\; label="C\; fb\; C"\; filenames="HDA00002457315500021.png"\; state="\{\{state\}\}">C</figure-callout>}}_{\mathrm{fb}}}{C}_{}{}_0+\frac{V_1\left[n\right]}{C_{\mathrm{fb}}}{C}_1+\frac{V_2\left[n\right]}{{\mathrm{<figure-callout\; id="2"\; label="C\; fb\; C"\; filenames="HDA00002457315500021.png"\; state="\{\{state\}\}">C</figure-callout>}}_{\mathrm{fb}}}{C}_{}{}_2+...+\frac{V_{14}\left[n\right]}{C_{\mathrm{fb}}}{C}_{14},$ (formula four)

Wherein C _fbthe electric capacity that capacitor C fb is feedback in representative, C ₀~ C ₁₄be respectively the electric capacity of tested capacitor C 0 ~ C14, V ₀[n]～V ₁₄[n] is respectively the sampling value of input signal V0 ~ V14.Known to persond having ordinary knowledge in the technical field of the present invention, the internal circuit that adds up module 42 also exists other kind to realize possibility.As long as can make digital signal A[n] comprise V ₀[n] * C ₀, V ₁[n] * C ₁..., V ₁₄[n] * C ₁₄deng the way circuit that adds of the inferior summation of 15 items, just can be applicable to this.

It should be noted that, input signal V0 ~ the V14 producing according to maximal-length sequence can not occur being the situation of in-phase signal entirely simultaneously, add resultant signal Vo and therefore can not occur peak value as the prior art that Fig. 3 presented, namely there is lower peak value to average ratio (PAPR).Hence one can see that, and electric capacity pick-up unit according to the present invention can adopt the less operational amplifier in linear operation interval and the less analogue-to-digital converters of input voltage range, to reach the effect of the amount of saving energy and hardware cost.

Be C through multiplier _fbmultiplier 44 after, digital signal A[n] be adjusted to digital signal B[n]:

B[n]=V ₀[n]C ₀+V ₁[n]C ₁+V ₂[n]C ₂+...+V ₁₄[n]C ₁₄。(formula five)

Subsequently, digital signal B[n] be provided to 15 different arithmetic paths as multiplicand.Multiplier 45A ~ 45O multiplier is separately V ₀[n], V ₁[n] ..., V ₁₄[n].With multiplier V ₀the path of [n] is example, is input signal V through multiplier ₀after the multiplier 45A of [n], digital signal B[n] be adjusted to digital signal D ₀[n]:

$D_0\left[n\right]=V_0^2\left[n\right]C_0+V_0\left[n\right]V_1\left[n\right]C_1+V_0\left[n\right]V_2\left[n\right]C_2+...+V_0\left[n\right]V_{14}\left[n\right]C_{14}.$

(formula six)

In practice, the multiplier C that multiplier 44 provides _fbalso can be integrated in the multiplier of multiplier 45A ~ 45O, or contraction in multiplication device 44 is directly by estimation module 47 processing digital signal A[n], to reduce the number of multipliers in circuit.

Integrator 46A is responsible for digital signal D ₀[n] integration, its integral result E ₀[n] can be expressed as follows:

E ₀[n]＝E ₀[n-1]+D ₀[n]。(formula seven)

In this embodiment, the integrating range length of integrator 46A equals the maximal-length sequence cycle T indicating in Fig. 5 (A).Taking the waveform of input signal V0 ~ V14 as the square wave shown in Fig. 5 (A) is as example.Suppose estimation module 47 every time T from this integral result E ₀once and make integrator 46A restart integration, and the multiplied result of the voltage of two signals when identical be 1 in [n] sampling, and the asynchronous multiplied result of the voltage of two signals is-1.Based on the characteristic of maximal-length sequence, if integrating range length equals T, signal V ₀[n] ~ V ₁₄in [n], any signal and this signal itself integral result after multiplying each other can be 15.Relatively, signal V ₀[n] ~ V ₁₄integral result in [n] after any two signal multiplications can be-1.Therefore sampling result Z after the standardization that, estimation module 47 obtains from the output terminal of integrator 46A ₀for:

Z ₀＝15C ₀-C ₁-C ₂-...-C ₁₄。(formula eight)

In like manner, sampling result Z after the standardization that estimation module 47 obtains from the output terminal of integrator 46B ₁for:

Z ₁＝15C ₁-C ₀-C ₂-...-C ₁₄。(formula nine)

The rest may be inferred, estimation module 47 altogether can be after integrator 46A ~ 46O obtains 15 standardization sampling result.According to these 15 simultaneous equations orders, estimation module 47 just can estimate 15 electric capacity C ₀~ C ₁₄.For example, sampling result Z after 15 standardization ₀~ Z ₁₄summation S be:

S=Z ₀+Z ₁+...+Z ₁₄＝C ₀+C ₁+C ₂+...+C ₁₄。(formula ten)

By summation S and sampling result Z ₀the result being added is 16*C ₀.Further this addition result is drawn to C divided by 16 ₀size.Fig. 6 is in the time that the integrating range length of integrator 46A ~ 46O all equals T, a kind of internal circuit example of estimation module 47.

Should be noted that, the integrating range length of each integrator is not limited to cycle T, also not necessarily all identical.For example, as long as integrating range length and corresponding sampling interval time are all a specific integral multiple of cycle T, the sampling result that estimation module 47 obtains is the integral multiple of aforementioned sampling result.On the other hand, if the integrating range length of each integrator is not isometric, its impact is only that the coefficient of these simultaneous equations orders can not be limited to 15 and-1.Even if the integral multiple of the integrating range length of these integrators each unequal and non-periodic of T, as long as estimation module 47 is learnt these integrating range length in advance, just can suitably select corresponding sample time, also can learn the coefficient of these simultaneous equations orders, therefore still can extrapolate electric capacity C ₀~ C ₁₄.

It should be noted that the function that adopts analog multiplier and integrator can realize equally above-mentioned reckoning electric capacity in pick-up unit 400, therefore analogue-to-digital converters 43 inessential element.

In addition, should be noted that, the number of cells that the quantity of tested electric capacity comprises with this maximal-length sequence not necessarily will equate just.For example, in the time that the quantity of tested electric capacity is 14, the deviser of pick-up unit 400 can be in aforementioned signal V0 ~ V14 optional 14 signals as input signal.Or in the time that the quantity of tested electric capacity is 22, deviser can adopt the pick-up unit 400 in Fig. 4 to detect 15 electric capacitys wherein, and detects other seven electric capacitys with another set detecting device.This another set detecting device can equal seven maximal-length sequence according to total bit number and produce its input signal.

In another embodiment, as shown in Figure 7, pick-up unit 400 further comprises the low-pass filter 48A ~ 48O being separately positioned in nonidentity operation path, its role is to the high frequency noise in the output signal of filtering multiplier 45A ~ 45O.

It should be noted that according to the signal noise of pick-up unit 400 of the present invention and be better than prior art than performance.Suppose sampling result Z after standardization that estimation module 47 obtains ₀~ Z ₁₄respectively carry noise composition I _zi:

$\left\{\begin{array}{c}{\mathrm{<figure-callout\; id="0"\; label="Z"\; filenames="HDA00002457315500021.png"\; state="\{\{state\}\}">Z</figure-callout>}}_0=15C_0-C_1-C_2-...-C_{14}+I_{Z0}\\ Z_1=15C_1-C_0-C_2-...-C_{14}+I_{Z1}\\ {\mathrm{<figure-callout\; id="2"\; label="Z"\; filenames="HDA00002457315500021.png"\; state="\{\{state\}\}">Z</figure-callout>}}_2=15C_2-C_0-C_1-...-C_{14}+{\mathrm{<figure-callout\; id="2"\; label="I\; Z"\; filenames="HDA00002457315500021.png"\; state="\{\{state\}\}">I</figure-callout>}}_Z\\ .\\ .\\ .\\ Z_{14}=15C_{14}-C_0-C_1-...-C_{13}+I_{Z14}\end{array}\right.,$ (formula 11)

And each noise composition I _zienergy response be:

$\left\{\begin{array}{c}{\mathrm{\&sigma;}}_I^2=E\left[{\mathrm{<figure-callout\; id="0"\; label="I\; Z"\; filenames="HDA00002457315500021.png"\; state="\{\{state\}\}">I</figure-callout>}}_Z^0\right]=...=E\left[I_{Z14}^2\right]\\ E\left[I_{\mathrm{Zm}}{I}_{\mathrm{Zn}}\right]=0;m\&NotEqual;n\end{array}\right..$ (formula 12)

Sampling result Z after standardization ₀~ Z ₁₄addition result can be expressed as follows:

$S=\underset{i=0}{\overset{14}{\mathrm{\&Sigma;}}}{Z}_i={\mathrm{<figure-callout\; id="0"\; label="C"\; filenames="HDA00002457315500021.png"\; state="\{\{state\}\}">C</figure-callout>}}_0+C_1+{\mathrm{<figure-callout\; id="2"\; label="C"\; filenames="HDA00002457315500021.png"\; state="\{\{state\}\}">C</figure-callout>}}_2+...+C_{14}+{\mathrm{<figure-callout\; id="0"\; label="I\; Z"\; filenames="HDA00002457315500021.png"\; state="\{\{state\}\}">I</figure-callout>}}_Z+I_{Z1}+...+I_{Z14}.$ (formula 13)

As discussed previously, can be by sampling result Z after addition result S and standardization ₀~ Z ₁₄be added again divided by 16, to draw electric capacity C separately ₀~ C ₁₄estimated value:

$\left\{\begin{array}{c}{\hat{C}}_0=(Z_1+S)\frac{1}{16}={\mathrm{<figure-callout\; id="0"\; label="C"\; filenames="HDA00002457315500021.png"\; state="\{\{state\}\}">C</figure-callout>}}_0+\frac{1}{16}(2{\mathrm{<figure-callout\; id="0"\; label="I\; D"\; filenames="HDA00002457315500021.png"\; state="\{\{state\}\}">I</figure-callout>}}_D+I_{D1}+...+I_{D14})\\ {\hat{C}}_1=(Z_1+S)\frac{1}{16}=C_1+\frac{1}{16}({\mathrm{<figure-callout\; id="0"\; label="I\; D"\; filenames="HDA00002457315500021.png"\; state="\{\{state\}\}">I</figure-callout>}}_D+2I_{D1}+...+I_{D14})\\ .\\ .\\ .\\ {\hat{C}}_{14}=(Z_{14}+S)\frac{1}{16}=C_{14}+\frac{1}{16}({\mathrm{<figure-callout\; id="0"\; label="I\; D"\; filenames="HDA00002457315500021.png"\; state="\{\{state\}\}">I</figure-callout>}}_D+I_{D1}+...+2I_{D14})\end{array}\right..$ (formula 14)

Take a broad view of formula 12 and formula 14 can be found out, the signal noise ratio of each estimated value is:

$\mathrm{SNR}\&ap;\frac{16{\mathrm{<figure-callout\; id="2"\; label="C\; i"\; filenames="HDA00002457315500021.png"\; state="\{\{state\}\}">C</figure-callout>}}_i^{}}{{\mathrm{\&sigma;}}_I^2}.$ (formula 15)

From formula 14, the signal noise of pick-up unit 400 than the signal noise higher than prior art than 16 times (that is have 12dB gap).

Another specific embodiment according to the present invention is a kind of capacitance touch control system, wherein comprises a contact panel, a voltage generator, a totalling module, a N multiplier, a N integrator and an estimation module.This contact panel comprises N tested electric capacity.N is greater than 1 integer.In practical application, the quantity of multiplier and integrator can be adjusted according to the quantity of tested electric capacity.

This voltage generator is in order to produce N input signal and an i input signal is wherein provided to the i electric capacity in this N electric capacity.This N input signal different and correspond respectively to one of a maximal-length sequence and postpone after sequence or this maximal-length sequence itself.I is the integer index of scope between 1 to N.This totalling module provides this N input signal to N the reaction signal producing after this N electric capacity in order to add up, and adds resultant signal to produce one.An i multiplier in N multiplier in order to by this totalling signal times with this i input signal, with signal after producing an i and multiplying each other.An i integrator in N integrator is in order to signal integration after this i is multiplied each other, to produce signal after an i integration.Estimation module is in order to according to this N of Signal estimation electric capacity electric capacity separately after this N integration.The various modes of circuit operation of previously having described in the time introducing pick-up unit 400 and change type (waveform of for example each input signal and relativeness) thereof also can be applied so far in capacitance touch control system, and its details repeats no more.

Another specific embodiment according to the present invention is a kind of detection method, and in order to coordinate a contact panel that comprises N electric capacity, its process flow diagram as shown in Figure 8.N is greater than 1 integer.First this detection method performs step S81, produces N input signal and an i input signal is wherein provided to the i electric capacity in this N electric capacity.This N input signal different and correspond respectively to one of a maximal-length sequence and postpone after sequence or this maximal-length sequence itself.I is the integer index of scope between 1 to N.Then, this detection method execution step S82, adds up this N input signal is provided to N the reaction signal producing after this N electric capacity, adds resultant signal to produce one.In step S83, this adds resultant signal and is multiplied by this i input signal, with signal after producing an i and multiplying each other.In step S84, after this i multiplies each other, signal is integrated, to produce signal after an i integration.Subsequently, this detection method execution step S85, according to this N of Signal estimation electric capacity electric capacity separately after this N integration.

Similarly, the various circuit operations of previously having described in the time introducing pick-up unit 400 change and also can be applied in the detection method that Fig. 8 illustrates, and its details repeats no more.

As mentioned above, the present invention proposes new electric capacity pick-up unit and detection method.By utilizing the signal producing according to maximal-length sequence as the voltage providing to tested electric capacity, can reach according to pick-up unit of the present invention and detection method the effect that simultaneously detects multiple capacitances, and can provide the signal noise that is better than prior art than performance.The peak value that must bear according to the circuit in pick-up unit of the present invention in addition, is low compared with prior art to average ratio.

By the above detailed description of preferred embodiments, hope can be known description feature of the present invention and spirit more, and not with the above-mentioned preferred embodiment being disclosed, category of the present invention is limited.On the contrary, its objective is that hope can contain in the category of the scope of the claims of being arranged in of various changes and tool equality institute of the present invention wish application.

Claims (17)

1. a pick-up unit, in order to detect N electric capacity in a contact panel, N is greater than 1 integer, and this pick-up unit comprises:

One voltage generator, in order to produce N input signal and an i input signal wherein provided to the i electric capacity in this N electric capacity, this N input signal different and correspond respectively to one of a maximal-length sequence and postpone after sequence or this maximal-length sequence itself, i is the integer index of scope between 1 to N;

One adds up module, in order to add up, this N input signal is provided to N the reaction signal producing after this N electric capacity, adds resultant signal to produce one;

N multiplier, an i multiplier wherein in order to by this totalling signal times with this i input signal, with signal after producing an i and multiplying each other;

N integrator, an i integrator is wherein in order to signal integration after this i is multiplied each other, to produce signal after an i integration; And

One estimation module, in order to according to this N of Signal estimation electric capacity electric capacity separately after this N integration.

2. pick-up unit as claimed in claim 1, is characterized in that, this maximal-length sequence comprises M bit altogether, and after this at least one delay, sequence is with respect to a retardation of this maximal-length sequence taking bit as unit, and M equals 2n-1, and n is greater than 1 integer.

3. pick-up unit as claimed in claim 1, is characterized in that, this maximal-length sequence has a cycle, and doubly, P is positive integer to the P that this N integrator integrating range length is separately this cycle.

4. pick-up unit as claimed in claim 3, is characterized in that, this estimation module is every one section of special time sample of signal after this i integration, and this special time is also P times of this cycle.

5. pick-up unit as claimed in claim 4, is characterized in that, this maximal-length sequence comprises M bit altogether, and M equals 2n-1, and n is greater than 1 integer, and N equals M, and this estimation module comprises:

One method of summated ratings device, in order to by signal plus after this N integration, to produce a total addition result;

N sub-totalizer, the sub-totalizer of an i is wherein in order to add this total addition result by signal after the i integration in signal after this N integration, to produce an i addition result; And

N divider, an i divider wherein in order to by this i addition result divided by P* (N+1), to produce this electric capacity of this i electric capacity.

6. pick-up unit as claimed in claim 1, is characterized in that, this N electric capacity has a first end and one second end separately, and this i input signal is provided this first end to this i electric capacity by this voltage generator, and this totalling module comprises:

One back coupling electric capacity; And

One operational amplifier, there is a first input end, one second input end and an output terminal, this first input end is coupled to a reference potential end, and this N electric capacity this second end is separately coupled to this second input end, and this back coupling electric capacity is coupled between this second input end and this output terminal.

7. pick-up unit as claimed in claim 5, is characterized in that, this totalling module further comprises:

One analogue-to-digital converters, are converted to a digital signal in order to the simulating signal that this output terminal of this operational amplifier is produced, and add resultant signal as this.

8. pick-up unit as claimed in claim 1, is characterized in that, further comprises:

N low-pass filter, an i low-pass filter is wherein arranged between this i multiplier and this i integrator, the high frequency noise after multiplying each other in order to this i of filtering in signal.

9. pick-up unit as claimed in claim 1, is characterized in that, this N input signal respectively do for oneself a square-wave signal, a triangular signal or a semicircle ripple signal.

10. a capacitance touch control system, comprises:

One contact panel, comprises N electric capacity, and N is greater than 1 integer;

One voltage generator, in order to produce N input signal and an i input signal wherein provided to the i electric capacity in this N electric capacity, this N input signal different and correspond respectively to one of a maximal-length sequence and postpone after sequence or this maximal-length sequence itself, i is the integer index of scope between 1 to N;

One adds up module, in order to add up, this N input signal is provided to N the reaction signal producing after this N electric capacity, adds resultant signal to produce one;

N multiplier, an i multiplier wherein in order to by this totalling signal times with this i input signal, with signal after producing an i and multiplying each other;

N integrator, an i integrator is wherein in order to signal integration after this i is multiplied each other, to produce signal after an i integration; And

One estimation module, in order to according to this N of Signal estimation electric capacity electric capacity separately after this N integration.

11. 1 kinds of detection methods, in order to detect N electric capacity in a contact panel, N is greater than 1 integer, and this detection method comprises:

(a) produce N input signal and an i input signal is wherein provided to the i electric capacity in this N electric capacity, this N input signal different and correspond respectively to one of a maximal-length sequence and postpone after sequence or this maximal-length sequence itself, i is the integer index of scope between 1 to N;

(b) add up this N input signal is provided to N the reaction signal producing after this N electric capacity, add resultant signal to produce one;

(c) by this totalling signal times with this i input signal, with signal after producing an i and multiplying each other;

(d) this i is multiplied each other after signal integration, to produce signal after an i integration; And

(e) according to this N of Signal estimation electric capacity electric capacity separately after this N integration.

12. detection methods as claimed in claim 11, is characterized in that, this maximal-length sequence comprises M bit altogether, and after this at least one delay, sequence is with respect to a retardation of this maximal-length sequence taking bit as unit, and M equals 2n-1, and n is greater than 1 integer.

13. detection methods as claimed in claim 11, is characterized in that, this maximal-length sequence has a cycle, and doubly, P is positive integer to the P that the integrating range length adopting in step (d) is this cycle.

14. detection methods as claimed in claim 13, is characterized in that, step (e) comprises every one section of special time sample of signal after this i integration, and this special time is also P times of this cycle.

15. detection methods as claimed in claim 13, is characterized in that, this maximal-length sequence comprises M bit altogether, and M equals 2n-1, and n is greater than 1 integer, and N equals M, and step (e) comprises:

By signal plus after this N integration, to produce a total addition result;

Signal after an i integration in signal after this N integration is added to this total addition result, to produce an i addition result; And

By this i addition result divided by P* (N+1), to produce this electric capacity of this i electric capacity.

16. detection methods as claimed in claim 11, is characterized in that, between step (c) and step (d), further comprise:

High frequency noise after this i of filtering multiplies each other in signal.

17. detection methods as claimed in claim 11, is characterized in that, this N input signal respectively do for oneself a square-wave signal, a triangular signal or a semicircle ripple signal.

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