CN101739186B - Image display system, capacitive touch panel and capacitance measuring device and method thereof - Google Patents
Image display system, capacitive touch panel and capacitance measuring device and method thereof Download PDFInfo
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- CN101739186B CN101739186B CN 200910007825 CN200910007825A CN101739186B CN 101739186 B CN101739186 B CN 101739186B CN 200910007825 CN200910007825 CN 200910007825 CN 200910007825 A CN200910007825 A CN 200910007825A CN 101739186 B CN101739186 B CN 101739186B
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Abstract
The invention provides an image display system, a capacitive touch panel and a capacitance measuring device and a capacitance measuring method thereof. The capacitive touch panel comprises a plurality of electrodes, a multiplexer and a capacitance measuring device, wherein the multiplexer can select an electrode to electrically connect the capacitance measuring device so as to judge contact capacitance; and the capacitance measuring device comprises a reference voltage source and a comparator, wherein the reference voltage source can generate a corrected reference voltage according to noise on a parasitic capacitor of the capacitive touch panel; and during a discharge process, the comparator compares the corrected reference voltage with an input voltage of the selected electrode so as to judge contact capacitance on the selected electrode. Because the noise can be eliminated under the differential comparison of the comparator, the capacitance measuring device can accurately measure the contact capacitance of the capacitive touch panel.
Description
Technical field
The invention relates to a kind of contact panel, particularly relevant for a kind of image display system, capacitance type touch-control panel and capacitance measuring device thereof and method.
Background technology
The application of contact panel (touch panel) is very extensive, for example ATM (Automatic Teller Machine), point-of-sale terminals, industrial control system etc.Along with popularizing of portable type electronic product such as intelligent mobile phone and PDA(Personal Digital Assistant), contact panel also provides imports not yet done user input mode more easily to button, so market is grown up quite quick.
Contact panel can mainly be divided into two kinds of resistance-type (resistive) contact panel and electric capacity (capacitive) formula contact panels according to its physical principle that detects touch point.Will produce voltage with finger or pointer flicking electric resistance touch-control panel; And capacitance type touch-control panel is to point touch panel and draw the operation of small current system.Moreover, capacitance type touch-control panel can be divided into surface capacitance type (surface capacitive) contact panel and projected capacitive (projected capacitive) contact panel again, wherein therefore projected capacitive touch panel more attracts industry competitively to research and develop owing to can reach multi-point touch (Multi-Touch) function.If projected capacitive touch panel is integrated into liquid crystal screen, to form embedded multi-point touch panel (In-Cell Multi-Touch Panel), more can keep the thinness of former panel.Transparency electrode (ITO) commonly used is pinned and is preserved electric charge in Thin Film Transistor-LCD (TFT LCD), same principle reverse operating, and this layer ITO also can work as sensor, and can provide high density to detect.Yet in TFT LCD, because the noise that TFT causes is very big, so the capacitance sensing control circuit is quite important.
Referring to Fig. 1, be the synoptic diagram of a prior art projected capacitive touch panel 200A, as shown in the figure, this projected capacitive touch panel 200A comprises a capacitance type touch-control panel unit 300A and a controller 30A.This capacitance type touch-control panel unit 300A has the strip shaped electric poles 32A of a dielectric base (not label), vertical direction, the strip shaped electric poles 34A of horizontal direction, and wherein this strip shaped electric poles 32A and strip shaped electric poles 34A are 90 degree angles.Fig. 1 only is a synoptic diagram of simplifying, and must know vertical strip shaped electric poles 32A and horizontal strip shaped electric poles 34A on the Different Plane of dielectric base (as front and reverse side), and number is respectively M bar and N bar.Therefore the incoming line of controller 30A is at least (M+N) bar.By the capacitance variations between vertical strip shaped electric poles 32A and the horizontal strip shaped electric poles 34A seizure electrode, but the contact position of controller 30A perception on this capacitance type touch-control panel unit 300A.
Referring to Fig. 2, be the sensing circuit 100A of a correlation technique (related art) capacitance type touch-control panel, this sensing circuit 100A for example can in be built in the controller 30A shown in first figure, to learn contact position by measuring capacitance variation.Suppose that Cs is the hand capacity that the vertical strip shaped electric poles 32A of finger contact k bar produces, Cp is stray capacitance (stray capacitance), and then this sensing circuit 100A can be charged to hand capacity Cs and stray capacitance Cp by a charging current source Ic with charge Q earlier.This sensing circuit 100A can be earlier via bigger first a current source 20A discharge, again via less second a current source 22A discharge subsequently.By formula Q=C * V as can be known if cause capacitor C to change because of the finger contact electrode, then the voltage at tie point P also can change, therefore compare the voltage (comparing with a reference voltage) of tie point P by a comparer 50A, know namely whether finger contacts k strip electrode bar.
More specifically, if this controller 30A periodically switches charge switch SW_C, the first discharge switch SW_A, the second discharge switch SW_B, then comparer 50A be output as pulsewidth can be with whether contacting pulse-width modulation (PWM) signal that changes.Controller 30A knows namely by reading the output pwm signal of sensing circuit 100A whether the vertical strip shaped electric poles 32A of k bar has finger contact and contact position.Sensing circuit 100A can select vertical strip shaped electric poles 32A and the horizontal strip shaped electric poles 34A of survey sheet 1 in regular turn, and controller 30A knows that namely the capacitance variations on described these electrodes reaches the contact position at projected capacitive touch panel.
Yet at the sensing circuit 100A of above-mentioned correlation technique capacitance type touch-control panel two shortcomings are arranged:
1. because stray capacitance Cp is generally speaking very big, be about 1000 times of hand capacity Cs of contact panel, therefore if at stray capacitance Cp noise is arranged, then can influence the detection degree of accuracy.Moreover, when this projected capacitive touch panel is used in LCD, because ITO electrode (formation electrode strip) and direct current common voltage (DCVCOM) electrode on the LCD upper plate are very approaching, therefore can make stray capacitance Cp become big, cause hand capacity Cs to measure difficulty.In addition, the sensing circuit 100A regular meeting of position on lower plate has very big noise to be coupled to the stray capacitance Cp of upper plate, causes the measurement mistake.
2. owing to need (M+N) signal line direct into sensing circuit 100A for the horizontal strip shaped electric poles 34A of the vertical strip shaped electric poles 32A of M bar and N bar, so distribution is comparatively complicated.
Summary of the invention
Therefore a purpose of the present invention is namely providing a kind of capacitance measuring device that reduces the capacitance type touch-control panel of noise.
Therefore another object of the present invention is namely providing a kind of capacitance type touch-control panel that reduces noise.
In order to reach above-mentioned purpose, the invention provides a kind of capacitance measuring device of capacitance type touch-control panel, this capacitance measuring device comprises: one first discharge current source is electrically connected to this tie point so that one first discharge current to be provided; One second discharge current source is electrically connected to this tie point so that one second discharge current to be provided, and wherein this first discharge current is greater than this second discharge current; One differential comparator has a first input end and one second input end, and this first input end is electrically connected to this tie point; One reference voltage source, be electrically connected to this second input end, this reference voltage source receives the direct current common voltage (DCVCOM) of a reference voltage and a LCD to produce a corrected reference voltage relevant with this direct current common voltage, and wherein the direct current common voltage of this LCD also is electrically connected to this contact panel.This differential comparator is compared a input voltage on this tie point and this corrected reference voltage to produce a pulse-width modulation signal that represents this hand capacity value, can be reduced in the noise on the direct current common voltage by this.
In order to reach above-mentioned purpose, the invention provides a kind of capacitance type touch-control panel, comprise: first electrode that has the first number M at longitudinal direction; Has second number N, second electrode at transverse direction; An and capacitance measuring device.This capacitance measuring device comprises: one first discharge current source is electrically connected to this tie point so that one first discharge current to be provided; One second discharge current source is electrically connected to this tie point so that one second discharge current to be provided, and wherein this first discharge current is greater than this second discharge current; One differential comparator has a first input end and one second input end, and this first input end is electrically connected to this tie point; One reference voltage source, be electrically connected to this second input end, this reference voltage source receives the direct current common voltage (DCVCOM) of a reference voltage and a LCD to produce a corrected reference voltage relevant with this direct current common voltage, and wherein this direct current common voltage also is electrically connected to this contact panel.This differential comparator is compared a input voltage on this tie point and this corrected reference voltage to produce a pulse-width modulation signal that represents this hand capacity value, can be reduced in the noise on the direct current common voltage by this.
In order to reach above-mentioned purpose, the invention provides a kind of capacitance measurement method of capacitance type touch-control panel, described capacitance measurement method is measured a hand capacity of an electrode of described capacitance type touch-control panel, described capacitance measurement method comprises: a. provides one first discharge current source, be electrically connected to a tie point so that one first discharge current to be provided, this tie point is electrically connected with this electrode; B provides one second discharge current source, is electrically connected to described tie point so that one second discharge current to be provided, and wherein said first discharge current is greater than described second discharge current; C. provide a differential comparator to have a first input end and one second input end, described first input end is electrically connected to described tie point; D provides a reference voltage source, be electrically connected to described second input end, the direct current common voltage of described reference voltage source superposition one reference voltage and a LCD is to produce a corrected reference voltage relevant with described direct current common voltage, and wherein said direct current common voltage also is electrically connected to described contact panel; E. via this tie point for described electrode precharge after, to described electrode with the discharge of this first discharge current; F. described electrode is discharged with this second discharge current; G. at the described second discharge current interdischarge interval, compare described corrected reference voltage and the input voltage on described tie point, to judge described hand capacity.
Moreover according to a preferred embodiments of the present invention, this capacitance type touch-control panel has more a multiplexer, most switches with corresponding described these first electrodes and described these second electrodes, and produce the control signal of the 3rd number, wherein the 3rd number adds one for the greater of this first number and this second number.This multiplexer is by described these switches of described these control signal controls, one of them is electrically connected to this capacitance measuring device to select described these first electrodes and described these second electrodes, to measure the hand capacity that is selected electrode, can reduce line number signal by this.
Description of drawings
Fig. 1 is the synoptic diagram of a prior art projected capacitive touch panel.
Fig. 2 is the sensing circuit circuit diagram of a correlation technique (related art) capacitance type touch-control panel.
Fig. 3 is the circuit diagram according to the capacitance measuring device of the capacitance type touch-control panel of the present invention's one preferred embodiments.
Fig. 4 A is depicted as a calcspar of multiplexer of the present invention.
Fig. 4 B is depicted as the partial circuit figure of multiplexer among Fig. 4 A.
Fig. 5 is the circuit diagram according to the reference voltage source of preferred embodiments of the present invention.
Fig. 6 is the circuit diagram according to the first discharge current source of preferred embodiments of the present invention.
Fig. 7 is the circuit diagram according to the differential comparator of preferred embodiments of the present invention.
Fig. 8 is the circuit diagram according to first low-pass filter of preferred embodiments of the present invention.
Fig. 9 is the capacitance measuring device operation waveform diagram of explanation preferred embodiments of the present invention.
Figure 10 is explanation capacitance measurement method process flow diagram of the present invention.
Figure 11 is the block schematic diagram according to the image display system of another instantiation of the present invention.
Drawing reference numeral:
Contact panel 200A contact panel unit 300A
Strip shaped electric poles 32A, 34A
The first current source 20A, the second current source 22A
Multiplexer 10 capacitance measuring devices 100
The charging current source Ic first discharge current source 20
The second discharge current source, 22 reference voltage sources 30
First low-pass filter, 40 second low-pass filters 42
The charge switch SW_C first discharge switch SW_A
The second discharge switch SW_B
Directions X switch S X1-SXM Y-direction switch S Y1-SYN
XY control signal SWXY switch controlling signal SW1-SWM
Electrode X1-XM
The first change-over switch capacitor C 11, C12, C13
The second change-over switch capacitor C 21, C22 storage capacitors Cx
Thin film transistor (TFT) is to A-F transistor Q1-Q7
Capacitance type touch-control panel 200 display modules 300
Step S100-S106
Embodiment
See also Fig. 3, circuit diagram for the capacitance measuring device 100 of the capacitance type touch-control panel of foundation the present invention one preferred embodiments, this capacitance measuring device 100 can cooperate a multiplexer 10 to use, and sees aftermentioned for details with the hand capacity Cs(that optionally measures a certain electrode on the projected capacitive touch panel unit 300A as shown in Figure 1).For the purpose of simplifying the description, the similar figure number of the use of part similar elements and Fig. 1 and Fig. 2, though do not see drawing, but must know that multiplexer 10 and this capacitance measuring device 100 are subjected to a controller (not shown) and control, select, provide operation clock pulse and the work of interpretation contact position to carry out electrode.
As shown in Figure 3, this capacitance measuring device 100 comprises a differential comparator 50, is connected to first low-pass filter 40 and second low-pass filter 42, the reference voltage source 30 that is connected to second low-pass filter 42, the charging current source Ic that is electrically connected with the contact P of first low-pass filter 40 and this multiplexer 10, the first discharge current source 20 (the first discharge current IL is provided), the second discharge current source 22 (the second discharge current IS is provided) of first input end (for example for non-inverting input V+) and second input end (for example being inverting input V-) of differential comparator 50 respectively.Moreover this charging current source Ic, this first discharge current source 20 and this second discharge current source 22 are respectively by charge switch SW_C, the first discharge switch SW_A, and the second discharge switch SW_B institute switching controls.The output of this comparer 50 is connected to an output buffer 60, further to link the controller analysis.
Fig. 4 A is depicted as a calcspar of this multiplexer 10, and this multiplexer 10 can be used for projected capacitive touch panel unit 300A as shown in Figure 1, so Fig. 4 A also comprises projected capacitive touch panel unit 300A in order to explanation.This multiplexer 10 comprises the M group switch S X1-SXM of vertical (longitudinal direction) strip shaped electric poles 32A of corresponding M bar and corresponding to the N group switch S Y1-SYN of N bar level (transverse direction) strip shaped electric poles 34A.Suppose M＞N, then multiplexer 10 only needs M+1 group control signal can control M group directions X switch S X1-SXM and N group Y-direction switch S Y1-SYN.More specifically, if multiplexer 10 will be selected k group directions X switch, to export k strip electrode signal to tie point P, then multiplexer 10 can be selected the directions X switch by XY control signal SWXY, select k group directions X electrode to export tie point P to by switch controlling signal SW1-SWM again, and with all the other non-selected electrode groundings.Moreover, if multiplexer 10 will be selected k group Y-direction switch, to export k strip electrode signal to tie point P, then multiplexer 10 can be selected the Y-direction switch by XY control signal SWXY, select k group Y-direction electrode to export tie point P to by switch controlling signal SW1-SWN again, and with all the other non-selected electrode groundings.Therefore this multiplexer 10 only need 1+Max (M, N) signal line (be 1+M at this example, because M〉N) and (M+N) the group switch can control M group directions X switch S X1-SXM and N group Y-direction switch S Y1-SYN, significantly reduce signal wire and use number.
Fig. 4 B is depicted as the partial circuit figure of this multiplexer 10, is mainly the circuit of corresponding M group directions X switch S X1-SXM, and the circuit of corresponding N group Y-direction switch S Y1-SYN also can the rest may be inferred.As shown in the drawing, each switch comprises four transistors, and optionally described these switches is received tie point P or ground connection by control signal SWk (k=1..M) and SWXY.More specifically, (SX1-SXM SY1-SYN) has four transistors to each switch, and wherein two strings of transistors are connected between tie point P and the electrode (X1-XM), and two transistors are connected between a ground connection and the electrode (X1-XM) in addition.
Referring to Fig. 5, be the circuit diagram of the capacitance measuring device 100 employed reference voltage sources 30 of foundation the present invention one preferred embodiments.This reference voltage source 30 comprises the change-over switch capacitor C 11 that a reference voltage Vref, a direct current common voltage (DCVCOM), five are subjected to first clock pulse and the control of second clock pulse respectively, C12, C13, C21, C22, and storage capacitors Cx.Referring to Fig. 9, this first clock pulse CLK1 and the second clock pulse CLK2 are nonoverlapping clock pulse in time each other, when the first clock pulse CLK1 conducting (the second clock pulse CLK2 closes), the first change-over switch capacitor C 11, C12, closed and the second change-over switch capacitor C 21 of C13, C22 opens, so reference voltage Vref can be stored in the storage capacitors Cx.When the second clock pulse CLK2 conducting (the first clock pulse CLK1 closes), the second change-over switch capacitor C 21, closed and the first change-over switch capacitor C 11 of C22, C12, C13 opens, therefore reference voltage Vref and direct current common voltage (DCVCOM) stack (superimposed) can be produced a corrected reference voltage Vref ', this corrected reference voltage Vref ' delivers to second input end of differential comparator 50 and handles.If direct current common voltage (DCVCOM) has noise, with reference to figure 3, noise also can be coupled to the first input end of differential comparator 50 by stray capacitance Cp.By reference voltage source 30 of the present invention, because corrected reference voltage Vref ' also has the stack composition that comes from direct current common voltage (DCVCOM), therefore can eliminate noise by differential mode, increase precision of measurement.When this capacitance type touch-control panel was used for the contact panel of LCD, this reference voltage source 30 can be eliminated the noise from the direct current common voltage.More specifically, in LCD, must reduce scintillation by adjusting direct current common voltage (DCVCOM), and the common electrode of the common voltage of upper and lower plates (common electrode) connects by the outer conduction gold size of array.Because capacitance type touch-control panel is to be positioned at upper plate when being used for the contact panel of LCD, so the capacitance measuring device of capacitance type touch-control panel must overcome from lower plate and sees through the noise that common electrode is coupled to upper plate; The corrected reference voltage Vref ' that is superimposed with direct current common voltage (DCVCOM) noise by generation reaches differential comparison, can reduce the noise from lower plate.
Referring to Fig. 6, be the circuit diagram in the capacitance measuring device 100 employed first discharge current sources 20 of foundation the present invention one preferred embodiments.This first discharge current source 20 comprises input TFT transistor and six thin film transistor (TFT)s (TFT) to (A-F), with provide one tie point P voltage by-5V to 7V(or bigger) current source of big discharge current all can be provided during variation.At tie point P voltage be-during 5V, six TFT transistors to (A-F) in the zone of saturation operation, if tie point P voltage by-when 5V changed to 7V, the TFT transistor can enter the range of linearity one by one to (F-B); Yet the drop of pressure of VDDD voltage and tie point P the TFT transistor to A on, so the TFT transistor still operates in saturation mode to A, and certain electric current is provided.The current source of big discharge current all can be provided during by tie point P change in voltage.
Referring to Fig. 7, be the circuit diagram of the capacitance measuring device 100 employed differential comparators 50 of foundation the present invention one preferred embodiments.This differential comparator 50 comprises 7 transistor Q1-Q7, and wherein positive voltage VDDA is connected to transistor Q1-Q3, and the Q5 gate provides first input end, and the Q4 gate provides second input end.Transistor Q6-Q7 is connected to reference bias Vb and negative voltage VSSA so that the bias voltage benchmark to be provided.The contact of transistor Q3 and Q7 then provides the output of differential comparator 50, and the differential comparator of a comparison input voltage vin and corrected reference voltage Vref ' is provided by this.
Referring to Fig. 8, be the circuit diagram of capacitance measuring device 100 employed first low-pass filters 40 of foundation the present invention one preferred embodiments.Existing low-pass filter for example can be resistance-capacitance circuit (RC circuit), and load termination is on electric capacity, first low-pass filter 40 of the present invention comprises the RC circuit of three serial connections, and the resistance value of each serial connection level (stage) is 1/3 of original single RC low-pass filter, and capacitance also is 1/3 of original low-pass filter, can reduce low-pass cut-off frequencies like this, effectively suppress noise.According to inventor's analysis, if the RC circuit of serial connection surpasses level Four, then can make filtering waveform variation.Moreover second low-pass filter 42 also can be taked the multistage implementation identical with first low-pass filter 40, with effective reduction noise.
Referring to Fig. 9, be the oscillogram that the capacitance measuring device 100 of explanation the present invention one preferred embodiments is operated, waveform shown in the figure is the complete testing process for an electrode.With reference to figure 3 and Fig. 9, at first the charging current of controller control precharge switch SW_C self-charging in the future current source Ic is to hand capacity Cs and stray capacitance Cp charging simultaneously.Controller is controlled the first charge switch SW_A and the second charge switch SW_B respectively subsequently.And the electric charge of hand capacity Cs and stray capacitance Cp is discharged by bigger first current source 20 (electric current I L is provided) discharge and the second less current source 22 (current IS is provided) respectively.At less second current source, 22 discharge regimes, controller can be controlled the first clock pulse CLK1 and the second clock pulse CLK2, to produce the corrected reference voltage Vref ' of reference voltage source 30.Differential comparator 50 comparison corrected reference voltage Vref ' reach the input signal Vin from hand capacity Cs and stray capacitance Cp, can produce pulse-width modulation (PWM) output signal (Vout).Controller can judge that the pulsewidth of PWM output signal is to judge capacitance variations.Therefore cooperate shown in Fig. 4 A and Fig. 4 B, select X or Y-direction switch when multiplexer 10 by control signal SWXY, select specific electrodes to export tie point P to by control signal SW1-SWM again, and with all the other non-selected electrode groundings; Controller can be by the pulsewidth of PWM output signal judging capacitance variations, and then judge contact position.Moreover controller can be compared this corrected reference voltage and this input voltage at this second discharge current interdischarge interval, producing a plurality of pulse-width modulation signals, and judges this hand capacity by the mean value of described these pulse-width modulation signals.
Referring to Figure 10, be the capacitance measurement method process flow diagram that explanation uses the capacitance measuring device of capacitance type touch-control panel to carry out, wherein this capacitance measurement method is measured a hand capacity Cs of an electrode of this capacitance type touch-control panel.This capacitance measurement method at first via a tie point P for this electrode precharge after, this electrode is discharged with one first discharge current, wherein this first discharge current can provide (S100) by the first discharge current source 20 shown in Figure 6.Subsequently this electrode is discharged with one second discharge current, wherein this first discharge current is greater than this second discharge current (S102).This capacitance measurement method then provides a corrected reference voltage Vref ', this corrected reference voltage Vref ' is the stack result of a reference voltage Vref and a direct current common voltage (DCVCOM), and this direct current common voltage (DCVCOM) also is electrically connected to this contact panel (S104).At last, at this second discharge current interdischarge interval, compare this corrected reference voltage Vref ' and the input voltage vin on this tie point P, with the numerical value (S106) of judging this hand capacity.
Moreover when above-mentioned step S104, this corrected reference voltage Vref ' can be provided by reference voltage source shown in Figure 5 30.This reference voltage source 30 comprises a plurality of first change-over switch capacitor C 11, C12, C13, a plurality of second change-over switch capacitor C 21, C22 and a storage capacitors Cx, wherein said these first change-over switch capacitor C 11, C12, C13 and described these second change-over switch capacitor C 21, (CLK1 CLK2) switches C22 in turn, so that this reference voltage Vref and the stack of this direct current common voltage (DCVCOM) are to produce this corrected reference voltage Vref ' by nonoverlapping clock pulse of time.In the same manner, cooperate Fig. 3 and Fig. 8, this corrected reference voltage Vref ' and this input voltage vin can be done low-pass filtering treatment earlier before comparison, and wherein low-pass filtering treatment is undertaken by a plurality of series resistor-condenser networks.Moreover, in above-mentioned step S104, at this second discharge current interdischarge interval, this corrected reference voltage of sustainable comparison Vref ' and this input voltage, producing a plurality of pulse-width modulation signals, and judge this hand capacity by the mean value of described these pulse-width modulation signals.
Referring to Figure 11, be the block schematic diagram of the image display system 500 of another instantiation of foundation the present invention.This image display system 500 comprises a display module 300, wherein this display module 300 has a capacitance type touch-control panel 200 (for example capacitance type touch-control panel 200A shown in Fig. 4 A), wherein capacitance measuring device 100 and multiplexer 10 shown in Fig. 3 of the present invention, Fig. 4 A and Fig. 4 B can be arranged on the capacitance type touch-control panel 200 or be arranged at outside the capacitance type touch-control panel 200.One load module 400 is coupled to display module 300, will comprise the input signal display module 300 of signal of video signal, show image after treatment.This display module 300 can be a LCD MODULE or an organic electric-excitation luminescent (OLED) display module.This image display system 500 for example can be a personal digital assistant (personal digital assistant, PDA), one display (display), one mobile computer (notebook computer), one digital camera (digital camera), one automobile-used display (car display), one flat computer (panel computer), one TV (television), one GPS (global positioning system, GPS), one aviation display (avionics display), one digital photo-frame (digital photo frame), one portable DVD player projector (portable DVD player) or a mobile phone (mobile phone) or other portable electron devices.
The corrected reference voltage that capacitance type touch-control panel of the present invention and capacitance measuring device thereof and method produce with reference current source is with superimposed noise, again by differential comparison to remove noise, can increase the comparison degree of accuracy.Moreover capacitance measuring device of the present invention provides first a discharge current source that burning voltage is arranged, and can promote the comparison resolution.
In sum, the present invention has had industry applications, novelty and progressive, and structure of the present invention had not seen like product and public use yet again, met the application for a patent for invention important document fully, so file an application according to Patent Law.
Claims (10)
1. the capacitance measuring device of a capacitance type touch-control panel is characterized in that, the electrode that described capacitance measuring device is electrically connected to described capacitance type touch-control panel via a tie point is to measure the hand capacity of described electrode, and described capacitance measuring device comprises:
One first discharge current source is electrically connected to described tie point so that one first discharge current to be provided;
One second discharge current source is electrically connected to described tie point so that one second discharge current to be provided, and wherein said first discharge current is greater than described second discharge current;
One differential comparator has a first input end and one second input end, and described first input end is electrically connected to described tie point;
One reference voltage source, be electrically connected to described second input end, described reference voltage source receives the direct current common voltage of a reference voltage and a LCD to produce a corrected reference voltage relevant with described direct current common voltage, and wherein said direct current common voltage also is electrically connected to described contact panel;
Described differential comparator is compared a input voltage on the described tie point and described corrected reference voltage to produce a pulse-width modulation signal of the described hand capacity value of representative.
2. capacitance measuring device as claimed in claim 1, it is characterized in that, described reference voltage source comprises a plurality of first change-over switch electric capacity that are electrically connected on described reference voltage and described direct current common voltage, a plurality of second change-over switch electric capacity and a storage capacitors, wherein said these first change-over switch electric capacity and described these second change-over switch electric capacity are switched in turn by nonoverlapping clock pulse of time, so that described reference voltage and described direct current common voltage superpose to produce described corrected reference voltage.
3. the capacitance measurement method of a capacitance type touch-control panel is characterized in that, described capacitance measurement method is measured a hand capacity of an electrode of described capacitance type touch-control panel, and described capacitance measurement method comprises:
A., one first discharge current source is provided, is electrically connected to a tie point so that one first discharge current to be provided, this tie point is electrically connected with this electrode;
B provides one second discharge current source, is electrically connected to described tie point so that one second discharge current to be provided, and wherein said first discharge current is greater than described second discharge current;
C. provide a differential comparator to have a first input end and one second input end, described first input end is electrically connected to described tie point;
D., one reference voltage source is provided, be electrically connected to described second input end, the direct current common voltage of described reference voltage source superposition one reference voltage and a LCD is to produce a corrected reference voltage relevant with described direct current common voltage, and wherein said direct current common voltage also is electrically connected to described contact panel;
E. via this tie point for described electrode precharge after, to described electrode with the discharge of this first discharge current;
F. described electrode is discharged with this second discharge current; And
G. at the described second discharge current interdischarge interval, compare described corrected reference voltage and the input voltage on described tie point, to judge described hand capacity.
4. capacitance measurement method as claimed in claim 3 is characterized in that, more comprises in step c:
A plurality of first change-over switch electric capacity, a plurality of second change-over switch electric capacity and a storage capacitors are provided, wherein said these first change-over switch electric capacity and described these second change-over switch electric capacity are switched in turn by nonoverlapping clock pulse of time, so that described reference voltage and described direct current common voltage superpose to produce described corrected reference voltage.
5. capacitance measurement method as claimed in claim 3 is characterized in that, more comprises in steps d:
At the described second discharge current interdischarge interval, compare described corrected reference voltage and described input voltage, producing a plurality of pulse-width modulation signals, and judge described hand capacity by the mean value of described these pulse-width modulation signals.
6. a capacitance type touch-control panel is characterized in that, described capacitance type touch-control panel comprises:
First electrode that has the first number M at longitudinal direction;
Second electrode that has second number N at transverse direction;
One capacitance measuring device is electrically connected to described these first electrodes and second electrode electrode to be measured wherein via a tie point, and to measure the hand capacity of described electrode to be measured, described capacitance measuring device comprises:
One first discharge current source is electrically connected to described tie point so that one first discharge current to be provided;
One second discharge current source is electrically connected to described tie point so that one second discharge current to be provided, and wherein said first discharge current is greater than described second discharge current;
One differential comparator has a first input end and one second input end, and described first input end is electrically connected to described tie point;
One reference voltage source, be electrically connected to described second input end, described reference voltage source receives the direct current common voltage of a reference voltage and a LCD to produce a corrected reference voltage relevant with described direct current common voltage, and wherein said direct current common voltage also is electrically connected to described contact panel;
Wherein said differential comparator is compared a input voltage on the described tie point and described corrected reference voltage to produce a pulse-width modulation signal of the described hand capacity value of representative.
7. capacitance type touch-control panel as claimed in claim 6, it is characterized in that, described capacitance type touch-control panel more comprises a multiplexer, a plurality of switches with corresponding described these first electrodes and described these second electrodes, and produce the control signal of the 3rd number, wherein said the 3rd number is that the greater among M and the N adds one;
Wherein said multiplexer is by described these switches of described these control signal controls, and one of them is electrically connected to described capacitance measuring device to select described these first electrodes and described these second electrodes, to measure the hand capacity that is selected electrode.
8. capacitance type touch-control panel as claimed in claim 7, it is characterized in that, described these control signals comprise an XY control signal and number is the switch controlling signal of the greater among M and the N, and wherein said XY control signal is electrically connected to each switch and handles with described these first electrodes of selection longitudinal direction or described these second electrodes of transverse direction; Described these switch controlling signals are electrically connected to corresponding switch to choose described these first electrodes and the processing wherein of described these second electrodes.
9. an image display system is characterized in that, described image display system comprises:
One display module has capacitance type touch-control panel as claimed in claim 6; And
One load module is coupled to described display module input signal is delivered to described display module, so that described display module show image.
10. as claim 9 a described image display system, it is characterized in that described image display system is a personal digital assistant, a display, a mobile computer, a digital camera, an automobile-used display, a flat computer, a TV, a GPS, aviation display, a digital photo-frame, a portable DVD player projector or a mobile phone.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 200910007825 CN101739186B (en) | 2008-11-21 | 2009-02-16 | Image display system, capacitive touch panel and capacitance measuring device and method thereof |
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| TWI569181B (en) * | 2014-10-21 | 2017-02-01 | 財團法人工業技術研究院 | Touch sensing method and touch sensing apparatus |
| US9811206B2 (en) | 2014-10-21 | 2017-11-07 | Industrial Technology Research Institute | Touch sensing method, touch display apparatus and portable electronic device |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| TWI569181B (en) * | 2014-10-21 | 2017-02-01 | 財團法人工業技術研究院 | Touch sensing method and touch sensing apparatus |
| TWI569186B (en) * | 2014-10-21 | 2017-02-01 | 財團法人工業技術研究院 | Touch sensing method and touch sensing apparatus |
| TWI587195B (en) * | 2014-10-21 | 2017-06-11 | 財團法人工業技術研究院 | Touch sensing method and portable device therewith |
| US9811206B2 (en) | 2014-10-21 | 2017-11-07 | Industrial Technology Research Institute | Touch sensing method, touch display apparatus and portable electronic device |
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