CN102253289A - Electric capacity measuring device for touch control device - Google Patents
Electric capacity measuring device for touch control device Download PDFInfo
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- CN102253289A CN102253289A CN2010101781109A CN201010178110A CN102253289A CN 102253289 A CN102253289 A CN 102253289A CN 2010101781109 A CN2010101781109 A CN 2010101781109A CN 201010178110 A CN201010178110 A CN 201010178110A CN 102253289 A CN102253289 A CN 102253289A
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Abstract
The invention relates to an electric capacity measuring device, which comprises a charging control unit, a discharging control unit, a switch unit, a second switch, a first analog-digital converter and a period detection circuit, wherein the charging control unit is used for charging a capacitor to be measured; the discharging control unit is used for discharging the capacitor to be measured; the first switch is used for controlling connection between the charging control unit and the capacitor to be measured according to a first switch signal; the second switch is used for controlling connection between the discharging control unit and the capacitor to be measured according to a second switch signal; the first analog-digital converter is used for converting a voltage on the capacitor to be measured into a first signal; and the period detection circuit is used for converting the voltage on the capacitor to be measured into a count value and outputting to a processing unit, wherein the count value represents the electric capacity of the capacitor to be measured.
Description
Technical field
The present invention relates to a kind of electric capacity that is used for a contactor control device and measure device, particularly measure device relevant for a kind of electric capacity that can accurately measure testing capacitance in the contactor control device.
Background technology
Touch Screen is made up of a transparent touch-control panel and a display screen, is used for various consumption electronic products, as user's operation-interface.Projected capacitive (Projected Capacitive) contact panel (Touch Panel) is one of a most widely used contact panel technology, has high sensitivity and durable advantage, and can realize the multi-point touch function.Please refer to Fig. 1, Fig. 1 is the functional block diagram of a known contactor control device 10.Contactor control device 10 includes a contact panel 100, a multiplexer 102, an electric capacity measurement device 104, a processing unit 106 and an internal memory 108.Contact panel 100 is a projected capacitive touch panel, has staggered ITO (tin indium oxide) sense wire of ranks with the induction touch action, each sense wire equivalence is the circuit that resistance and an electric capacity are formed, when human body touching contact panel 100, the changing of equivalent capacity volume production of touched sense wire.Multiplexer 102 is coupled to many sense wires of contact panel 100, is used for each sense wire of timesharing conducting and electric capacity to measure binding between the device 104, to finish the scanning of whole contact panel 100.Electric capacity is measured device 104, the equivalent capacity of the sense wire that is connected by multiplexer 102 promptly is a testing capacitance, electric capacity is measured device 104 the testing capacitance amount is converted to recordable numerical value, as emulation magnitude of voltage or digital count value, exports processing unit 106 to.
Testing capacitance when contact panel 100 is not touched is environment electric capacity (EnvironmentCapacitor), and its electric capacity is measured device 104 by electric capacity and is converted to corresponding one basic count value, is stored in internal memory 108.The size of environment electric capacity is different along with the characteristic of contact panel, the environment electric capacity accurately whether, also influence the correctness of touch detection.When contact panel 100 is subjected to the human body touching, the testing capacitance amount can change because body capacitance amount (Human Capacitance) adds, processing unit 106 with electric capacity measure New count value that device 104 conversion testing capacitance amounts are produced with corresponding to the basic count value of environment electric capacity relatively, can judge whether human body touching contact panel 100.
The mode that electric capacity is measured device 104 measurement testing capacitance amounts has different several modes, wherein the most easy mode is to connect testing capacitance with resistance or constant current source, discharge and recharge the time according to the principle measurement that discharges and recharges time τ=R * C, with estimation testing capacitance amount.The equivalent capacity of the sense wire of contact panel 100 self is minimum, approximately is tens of extremely hundreds of picofarads (pF), and when testing capacitance was environment electric capacity, the time that discharges and recharges was very short, and the measurement of testing capacitance amount may produce very mistake.Another way shifts (Charge Transfer) for carrying out electric charge, electric charge on the testing capacitance is shifted the integrating capacitor (Integrating Capacitor) that is stored to than high capacitance, and carry out one shift the voltage levvl that makes integrating capacitor to for several times electric charge and arrive a predetermined voltage level after, integrating capacitor is discharged, repeat above-mentioned electric charge transfer step again, up to obtaining accurate testing capacitance amount.Above-mentioned electric charge branch mode only utilizes estimates the testing capacitance amount discharge time of utilization to the time of integrating capacitor charging, and measurement efficient is lower.
The mode of another known measurement testing capacitance amount is the combination of above two kinds of modes, is called trigonometric integral (Delta-sigma) method.Please refer to Fig. 2, Fig. 2 is the synoptic diagram that a known trigonometric integral formula electric capacity is measured device 20, and electric capacity is measured device 20 and be can be used to measure device 104 as the electric capacity of Fig. 1.Electric capacity is measured device 20 and is made up of an integrating capacitor 200, a discharge circuit 202, a comparer 204, a digital signal processing unit 206 and switch SW 1, SW2.Please refer to Fig. 3, Fig. 3 is that the electric capacity of Fig. 2 is measured the sequential chart that device 20 discharges and recharges the coherent signal of program, is described under the different situation of the electric capacity of testing capacitance 22 the voltage V on the signal S1 of gauge tap SW1 and SW2 and S2, the integrating capacitor 200
CMAnd the sequential of the signal SB that exported of comparer 204, wherein dotted line and solid line represent that respectively the electric capacity of testing capacitance 22 reaches less situation more greatly.
Signal S1, S2 gauge tap SW1, SW2 respectively make power supply V in not conducting simultaneously
CCTo testing capacitance 22 chargings, then carry out electric charge and shift, the electric charge on the testing capacitance 22 is transferred to integrating capacitor 200.When carrying out the electric charge transfer, comparer 204 is with the voltage V on the integrating capacitor 200
CMWith a reference voltage V
REFCompare, produce a signal SB, simultaneously, digital signal processing unit 206 is converted to a count value Dx with signal SB.As voltage V
CMGreater than reference voltage V
REFThe time, 202 pairs of integrating capacitors 200 of signal SB control discharge circuit are discharged.As shown in Figure 3, when the electric capacity of testing capacitance 22 is bigger, the electric weight that is transferred to integrating capacitor 200 is also more, so the dutycycle of signal SB (DutyCycle) is bigger.
In brief, it is electric capacitys of representing testing capacitance 22 with the dutycycle of signal SB that electric capacity is measured device 20, and signal SB is converted to count value Dx, for the electric capacitance change of back-end processing circuit judges testing capacitance 22.Mode compared to the time that discharges and recharges of direct measurement testing capacitance 22 or the number of times estimation testing capacitance amount that only shifts according to electric charge, when testing capacitance is the minimum environment electric capacity of electric capacity, the result who measures device 20 measurement environment electric capacity gained with electric capacity is more accurate, it is also higher to measure efficient, but still have many shortcomings on real the work, be described as follows.
It is to charge with 22 pairs of known integrating capacitors of testing capacitance 200 of the unknown that electric capacity is measured device 20.Be applicable to the contact panel that measures various characteristics in order to make electric capacity measure device 20, the electric capacity of known integrating capacitor 200 must be much larger than the electric capacity of testing capacitance 22, be tens of how farads (nF) approximately, therefore, no matter integrating capacitor 200 is to be integrated in the integrated circuit or as external module, all to need very high cost.If integrating capacitor 200 is external modules, integrating capacitor 200 is disturbed by external electromagnetic ripple signal easily, causes the voltage V on the integrating capacitor 200
CMInstability, therefore, the signal SB that comparer 204 produces contains noise, influences the degree of accuracy of back-end processing circuit judges electric capacitance change.
On real the work, when finish discharge time, the voltage V on the integrating capacitor 200
CMMust return the initial voltage level in duration of charging; In other words, discharge capability must be greater than charging ability.When the electric capacity of testing capacitance 22 is very big, the quantity of electric charge that is transferred to integrating capacitor 200 by testing capacitance 22 electric charges is also big, and if this moment is the deficiency of time of 200 pairs of discharge circuits of integrating capacitor, 202 discharges, the voltage V on the integrating capacitor 200
CMCan't when finish discharge time, return the initial voltage level and additive effect occur.Please refer to Fig. 4, Fig. 4 is that electric capacity is measured the sequential chart that device 20 discharges and recharges the coherent signal of program.As shown in Figure 4, as voltage V
CMAdditive effect occurs, finally may reach voltage levvl identical when being full of electricity with testing capacitance 22, electric charge shifted and can not take place this moment, and electric capacity is measured device 20 can't bring into play the measurement effect.When the problems referred to above cause charging ability greater than discharge capability in the environmental factor drift, also take place easily.
On the other hand, when testing capacitance 22 during much smaller than integrating capacitor 200, the voltage variety that at every turn carries out on the integrating capacitor 200 of electric charge transfer back is minimum, relatively the discharge capability of discharge circuit 202 is bigger, need the longer time that integrating capacitor 200 is charged to effective scalable voltage levvl, cause the measurement waste of time.Moreover to judge the electric capacitance change of testing capacitance 22 too short discharge time, gained is out of true as a result.
As from the foregoing, measure in the device in known electric capacity, charging and discharging capabilities is the adjustable elasticity of tool not, can't reach identical degree of accuracy when being used for the contact panel of different qualities.In addition, when same contact panel uses or environmental factor when causing the environment electric capacity to change because of long-time, known electric capacity is measured device and method for measurement can't flexibly measure new environment electric capacity.Thus, when contact panel was touched, the back-end processing circuit may be because there be accurate environment electric capacity can't correctly detect the touch action of human body for relatively.
Summary of the invention
Therefore, fundamental purpose of the present invention promptly is to provide a kind of electric capacity that is used for a contactor control device to measure device, in order to accurately to measure the testing capacitance amount.
The invention provides a kind of electric capacity and measure device, be used for measuring the electric capacity of a testing capacitance, include: a charging control unit is used for to this testing capacitance charging; One discharge control module is used for to this testing capacitance discharge; One first switch is coupled to this testing capacitance and this charging control unit, is used for controlling the binding between this charging control unit and this testing capacitance according to one first switching signal; One second switch is coupled to this testing capacitance and this discharge control module, is used for controlling the binding between this discharge control module and this testing capacitance according to a second switch signal; One first analog to digital converter is coupled to this testing capacitance, and being used for the voltage transitions on this testing capacitance is one first signal; And one-period testing circuit, be coupled to this testing capacitance, being used for the voltage transitions on this testing capacitance is a count value, exports a processing unit to, this count value is represented the electric capacity of this testing capacitance.
Description of drawings
Fig. 1 is the functional block diagram of a known contactor control device.
Fig. 2 is that a known trigonometric integral formula electric capacity is measured schematic representation of apparatus.
Fig. 3 and Fig. 4 are that the electric capacity of Fig. 2 is measured the sequential chart that device discharges and recharges the coherent signal of program.
Fig. 5 is that the embodiment of the invention one electric capacity is measured schematic representation of apparatus.
Fig. 6 is that the electric capacity of Fig. 5 is measured device and is set at and fills under the situation of afterwards putting configuration the sequential chart of coherent signal when discharging and recharging program earlier.
Fig. 7 is that the electric capacity of Fig. 5 is measured device and is set at and puts under the situation of afterwards filling configuration the sequential chart of coherent signal when discharging and recharging program earlier.
Fig. 8 is that the electric capacity of Fig. 5 is measured device and is set at and fills earlier under the situation of afterwards putting configuration, the sequential chart of coherent signal when discharging and recharging program, and it describes the adjustment of charging ability.
Fig. 9 is that the electric capacity of Fig. 5 is measured device and is set at and fills earlier under the situation of afterwards putting configuration, the sequential chart of coherent signal when discharging and recharging program, and it describes the adjustment of discharge capability.
Figure 10 is that the electric capacity of Fig. 5 is measured device and is set at and fills earlier under the situation of afterwards putting configuration, the sequential chart of coherent signal when discharging and recharging program, and it describes the relation of testing capacitance amount and coherent signal.
Figure 11 is that the embodiment of the invention one electric capacity is measured schematic representation of apparatus.
Figure 12 is that the electric capacity of Figure 11 is measured device and is set at and fills earlier under the situation of afterwards putting configuration, the sequential chart of coherent signal when discharging and recharging program, and it describes the relation of testing capacitance amount and coherent signal.
Figure 13 is that the electric capacity of Figure 11 is measured device and is set at and puts earlier under the situation of afterwards filling configuration, the sequential chart of coherent signal when discharging and recharging program, and it describes the relation of testing capacitance amount and coherent signal.
Figure 14 is that the embodiment of the invention one electric capacity is measured schematic representation of apparatus.
Wherein, description of reference numerals is as follows:
10 contactor control devices, 510,610,710 cycle control circuits
100 contact panels, 512,612,712 voltage generation units
102 multiplexers 514,516,614, discharge and recharge control module
616、714、716
104 electric capacitys are measured device 518,618,718 analog to digital converters
106,502 processing units, 520,620,720 cycle detection circuit
108,504 internal memories, 522,622,722 analog to digital converters
20,50,60,70 electric capacitys are measured device SW1～SW3 switch
22,52,62,72 testing capacitance S1～S3, SB, SD, signal
SD2
200 integrating capacitor Dx, DL, DU count value
202 discharge circuit V
CMVoltage
204 comparer V
REF, V
U, V
L, reference voltage
V
REF1～V
REF3
206,524,624, digital signal processing is single
724 yuan
Embodiment
Please refer to Fig. 5, Fig. 5 is the synoptic diagram that the embodiment of the invention one electric capacity is measured device 50.Electric capacity is measured the equivalent electric capacity that device 50 is used for measuring the sense wire of a contact panel, and the equivalent capacity of sense wire is with a testing capacitance 52 expressions.Show a processing unit 502 and an internal memory 504 relevant among Fig. 5 in the lump with electric capacity measurement device 50.Electric capacity measure device 50 include one-period control circuit 510 and one-period testing circuit 520.Cycle control circuit 510 includes a voltage generation unit 512, discharges and recharges control module 514,516, an analog to digital converter (Analog-to-digital Converter) 518 and switch SW 1～SW3.Cycle detection circuit 520 includes an analog to digital converter 522 and a digital signal processing unit 524.
Cycle control circuit 510 is used for testing capacitance 52 is discharged and recharged.Voltage generation unit 512 is used for producing reference voltage V
RFF1, V
REF2And V
REF3Discharge and recharge control module 514 and 516 according to its hardware design, wherein a control module is made as the charging configuration, and in order to testing capacitance 52 is charged, another control module is made as the discharge configuration, in order to testing capacitance 52 discharges, describes in detail in the back.Adjustment to the charging and discharging capabilities of testing capacitance 52 can be illustrated in the variation in the cycle of discharging and recharging.The hardware implementation mode that discharges and recharges control module 514 and 516 is not limited to any ad hoc rules, but need guarantee that both chargings and discharge capability are to adjust, for example can use simple switch and adjustable electric capacity, adjustable electric capacity is precharged to carries out electric charge behind the suitable voltage levvl and shift, or with adjustable current source, or discharge and recharge control module (or claiming charging control unit) with what modes such as voltage source resistance in series realized charging configuration.In like manner, the discharging and recharging control module (or claim discharge control module) and can use adjustable current source to realize of discharge configuration, or directly pass through resistance eutral grounding.
It should be noted that the electric capacity that discharges and recharges control module of the configuration that is used for charging, its electric capacity can be very little and be integrated in electric capacity and measures in the integrated circuit of device 50, and is different with the integrating capacitor of known external high capacitance.Therefore, electric capacity is measured the cost that device 50 has been saved external capacitor, and because the electric capacity that discharges and recharges in the control module is not external module, is not easy to be disturbed by electromagnetic wave signal, and then guarantees the degree of accuracy that electric capacity is measured.
Analog to digital converter 518 is one 1 (bit) analog to digital converters, is equivalent to a comparer, is coupled to voltage generation unit 512 and testing capacitance 52, is used for according to reference voltage V
REF2With the voltage V on the testing capacitance 52
CMBe converted to a signal S3.In other words, analog to digital converter 518 is with voltage V
CMWith reference voltage V
REF2Compare, signal S3 represents comparative result.Switch SW 3 is coupled to analog to digital converter 518, discharges and recharges control module 516 and testing capacitance 52, be used for according to signal S3, control discharges and recharges the binding between control module 516 and the testing capacitance 52, make 516 pairs of testing capacitances of control module 52 discharge (or charging, decide) according to discharging and recharging the configuration of control module 516.
Analog to digital converter 522 is one 1 analog to digital converters, is equivalent to a comparer, is coupled to voltage generation unit 512 and testing capacitance 52, is used for according to reference voltage V
REF3With the voltage V on the testing capacitance 52
CMBe converted to a signal SB.Digital signal processing unit 524 is coupled to analog to digital converter 522, is used for signal SB being converted to count value Dx after through a plurality of runnings that discharge and recharge the cycle, exports processing unit 502 to.Digital signal processing unit 524 can be considered a totalizer, is signal SB to be taken a sample with a predetermined sampling frequency, and the accumulative total sampling result.In brief, cycle detection circuit 520 is with the voltage V on the testing capacitance 52
CMBe converted to count value Dx.Because voltage V
CMWaveform represent discharging and recharging the cycle of testing capacitance 52, and count value Dx is according to voltage V
CMAnd produce, so count value Dx represents the cycle that discharges and recharges of testing capacitance 52, also represents the electric capacity of testing capacitance 52.
Note that to discharge and recharge control module 514 and discharge and recharge control module 516 to be set at charging configuration or discharge configuration, the sequencing that carries out charge or discharge with electric capacity measurement device 50 is relevant.When discharging and recharging control module 514 are charging configurations and to discharge and recharge control module 516 are discharges during configuration, and electric capacity is measured 50 pairs of testing capacitances of device 52 and charged earlier and afterwards discharge, and is called to fill earlier and afterwards puts configuration.When discharging and recharging control module 514 are discharge configurations and to discharge and recharge control module 516 are chargings during configuration, and electric capacity is measured 50 pairs of testing capacitances of device 52 and discharged earlier and afterwards charge, and is called to put earlier and afterwards fills configuration, with Fig. 6 and Fig. 7 explanation.
Please refer to Fig. 6, Fig. 6 fills earlier under the situation of afterwards putting configuration for electric capacity measurement device 50 is set at, and the sequential chart of coherent signal when discharging and recharging program is wherein described signal S1～S3, voltage V
CMAnd signal SB.When discharging and recharging control module 514 are charging configurations and to discharge and recharge control module 516 are discharge configurations, and reference voltage is set at V
REF3〉=V
REF2≈ V
REF1The time, by signal shown in Figure 6 as can be known, switch SW 1 is closed after conducting a period of time when the program of discharging and recharging is initial, and testing capacitance 52 is precharged to reference voltage V
REF1When switch SW 2 conductings, discharge and recharge control module 514 and carry out the electric charge transfer, testing capacitance 52 chargings.Because reference voltage V
REF2Approximate reference voltage V
REF1, so voltage V
CMRise to soon and be greater than or equal to reference voltage V
REF2, the signal S3 gauge tap SW3 conducting that this moment, analog to digital converter 518 was exported discharges and recharges 516 pairs of testing capacitances 52 of control module and discharges.Discharging action continues to signal S3 gauge tap SW3 and closes, that is voltage V
CMBe less than or equal to reference voltage V
REF2The time till.Discharging and recharging control module 514 and begin to carry out electric charge and be transferred to and discharge and recharge control module 516 and stop to discharge during this period of time, is one to discharge and recharge the cycle.After a plurality of runnings that discharge and recharge the cycle, digital signal processing unit 524 is converted to count value Dx with signal SB.
Please refer to Fig. 7, Fig. 7 is put under the situation of afterwards filling configuration the sequential chart of coherent signal when discharging and recharging program earlier for electric capacity measurement device 50 is set at.When discharging and recharging control module 514 are discharge configurations and to discharge and recharge control module 516 are charging configurations, and reference voltage is set at V
REF3≤ V
REF2≈ V
REF1The time, by signal shown in Figure 7 as can be known, switch SW 1 is closed after conducting a period of time when the program of discharging and recharging is initial, and testing capacitance 52 is precharged to reference voltage V
REF1When switch SW 2 conductings, discharge and recharge control module 514 and carry out the electric charge transfer, testing capacitance 52 discharges.Voltage V on testing capacitance 52
CMDrop to and be less than or equal to reference voltage V
REF2The time, signal S3 gauge tap SW3 conducting discharges and recharges 516 pairs of testing capacitances 52 of control module and charges.The charging action continues to signal S3 gauge tap SW3 and closes, that is the voltage V on the testing capacitance 52
CMBe greater than or equal to reference voltage V
REF2Till.After a plurality of runnings that discharge and recharge the cycle, digital signal processing unit 524 is converted to count value Dx with signal SB.Measure device 50 in electric capacity and be set at and put earlier when afterwards filling configuration, above-mentioned reference voltage is set V
REF3≤ V
REF2≈ V
REF1Only be one embodiment of the invention, reference voltage also can be designed to V
REF3≤ V
REF2≤ V
REF1, to be applicable to the great situation of testing capacitance amount.
Specifically, processing unit 502 judges with a predetermined count value scope DL～DU whether count value Dx is too high or too low, correspondingly to adjust charging ability or discharge capability, the too high or too low expression environment of count value Dx electric capacity may change because of external factor.Predetermined count value scope can be set according to the maximum count value that processing unit 502 may receive, and for example upper limit count value DU is set at 80% of maximum count value, and lower limit count value DL is set at 20% of maximum count value.When count value Dx greater than upper limit count value DU, processing unit 502 judges that count value Dx are too high, must downgrade charging ability or increase discharge capability; When count value Dx less than lower limit count value DL, processing unit 502 judges that count value Dx are low excessively, must increase charging ability or downgrade discharge capability.The adjustment of 502 pairs of charging and discharging capabilities of processing unit is carried out till count value Dx is positioned at predetermined count value scope, and the charge or discharge ability of this moment is the most suitable setting.
Please refer to Fig. 8, Fig. 8 is that electric capacity is measured device 50 and is made as and fills under the situation of afterwards putting configuration the sequential chart of coherent signal when discharging and recharging program earlier.In Fig. 8, to suppose to discharge and recharge control module 514 and have three sections charging ability CC1, CC2, CC3 can select, the charging ability size order is CC1＜CC2＜CC3; Signal waveform corresponding to charging ability CC1, CC2, CC3 is represented with long dotted line, solid line, short dash line respectively.Charge with charging ability CC2 when discharging and recharging control module 514, processing unit 502 judges that count value Dx is too high simultaneously, be that the dutycycle of signal SB is when excessive, the charging ability that processing unit 502 will discharge and recharge control module 514 comes down to charging ability CC1, reduces and carries out the electric weight that electric charge shifts at every turn.As shown in Figure 8, when charging with charging ability CC1, the voltage V on the testing capacitance 52
CMIf originally so high, the dutycycle of signal SB does not diminish the amplitude of climbing, and cycle detection circuit 520 is correspondingly exported less count value Dx.
Similarly, charge with charging ability CC2 when discharging and recharging control module 514, simultaneously processing unit 502 learns that count value Dx is low excessively, and when promptly the dutycycle of signal SB was too small, the charging ability that processing unit 502 will discharge and recharge control module 514 increased and is charging ability CC3.At this moment, the dutycycle of signal SB correspondingly becomes greatly, and cycle detection circuit 520 is correspondingly exported bigger count value Dx.Processing unit 502 through one to for several times judgement count value Dx and adjust charging ability after, the charging ability that discharges and recharges control module 514 is set in the most suitable state.
Please refer to Fig. 9, Fig. 9 fills under the situation of afterwards putting configuration the sequential chart of coherent signal when discharging and recharging program earlier for electric capacity measurement device 50 is made as.In Fig. 9, to suppose to discharge and recharge control module 516 and have three sections discharge capability DC1, DC2, DC3 can select, the discharge capability size order is DC1＞DC2＞DC3; Signal waveform corresponding to discharge capability DC1, DC2, DC3 is represented with long dotted line, solid line, short dash line respectively.Discharge with discharge capability DC2 when discharging and recharging control module 516, simultaneously processing unit 502 learns that count value Dx is too high, and when promptly the dutycycle of signal SB was excessive, the discharge capability that processing unit 502 will discharge and recharge control module 516 increased and is discharge capability DC1, increase discharge capacity, shorten discharge time.As shown in Figure 9, when increasing, discharge capability is discharge capability DC1, the voltage V on the testing capacitance 52
CMComparatively fast drop to and be lower than voltage V
REF3, the dutycycle of signal SB diminishes, and cycle detection circuit 520 is correspondingly exported less count value Dx.
Similarly, discharge with discharge capability DC2 when discharging and recharging control module 516, processing unit 502 learns that count value Dx is low excessively simultaneously, be that the dutycycle of signal SB is when too small, the discharge capability that processing unit 502 will discharge and recharge control module 516 comes down to discharge capability DC3, reduces discharge capacity, increases discharge time, this moment, the dutycycle of signal SB correspondingly became greatly, and cycle detection circuit 520 is correspondingly exported bigger count value Dx.Processing unit 502 is set in the most suitable state with the discharge capability that discharges and recharges control module 516 after adjusting to discharge capability for several times through one.
Fig. 8 and Fig. 9 have shown that filling the electric capacity of afterwards putting configuration earlier measures in the device 50, and charging ability and discharge capability are corresponding to the relation of the dutycycle of signal SB.In like manner, afterwards fill configuration when electric capacity measurement device 50 is made as to put earlier, processing unit 502 also can be adjusted the discharge capability that discharges and recharges control module 514 and discharge and recharge the charging ability of control module 516, does not describe in detail at this.
When the environment electric capacity of contact panel changes because of external factor such as temperature, humidity or laying dust, known electric capacity is measured the count value that device produced may be too high or too low, has not been suitable for the judgement of touch event; Yet known electric capacity measurement device can not change the charging and discharging capabilities of testing capacitance.In this case, the count value that the processing unit of contactor control device obtains can't be represented correct testing capacitance amount, and whether the human body touch action that can't judge rightly takes place.
In comparison, in the contactor control device that uses electric capacity measurement device 50, when electric capacity is measured count value Dx that device 50 produced because of environment electric capacitance change when too high or too low, processing unit 502 is according to count value Dx, the charge or discharge ability of 510 pairs of testing capacitances 52 of adjustment cycle control circuit is applicable under the condition of new environment electric capacity charging ability or discharge capability.Thus, count value Dx can get back in the predetermined count value scope, and electric capacity is measured the function answer that device 50 measures the testing capacitance amount, thereby whether the touch action that can judge rightly takes place.
Please refer to Figure 10, Figure 10 fills under the situation of afterwards putting configuration the sequential chart of coherent signal when discharging and recharging program earlier for electric capacity measurement device 50 is made as.In Figure 10, represent with long dotted line, solid line, short dash line respectively that corresponding to the signal waveform of testing capacitance amount C1, C2, C3 testing capacitance amount size order is C1＜C2＜C3.According to the V=Q/C principle, suppose that testing capacitance amount originally is C2, the testing capacitance quantitative change the C3 greatly if electric weight that the electric charge that charges shifts is constant, voltage V
CMStep-down; Otherwise, if the electric weight that electric charge shifts is constant the testing capacitance quantitative change little be C1, voltage V
CMImprove.If measure discharge time according to discharging and recharging time τ=R * C principle, when the testing capacitance amount was C3 by the C2 increase, increased discharge time, and it is big that the dutycycle of signal SB becomes; Otherwise when the testing capacitance amount was reduced to C1 by C2, shortened discharge time, and the dutycycle of signal SB diminishes.As shown in Figure 10, the dutycycle of signal SB is represented the electric capacity of testing capacitance 52.In like manner, if measure device 50 and measure different testing capacitance amounts to put the electric capacity of afterwards filling configuration earlier, also the dutycycle of signal SB is represented the electric capacity of testing capacitance 52 as can be known, does not give unnecessary details at this.
In brief, electric capacity measures that 50 pairs of testing capacitances 52 of device discharge and recharge and with the voltage V on the testing capacitance 52
CMBe converted to count value Dx, export processing unit 502 to, processing unit 502 judges whether to adjust charging and discharging capabilities according to count value Dx.Therefore, electric capacity measurement device 50 can use suitable charging and discharging capabilities, and also can be used for measuring the contact panel of different qualities flexibly with the variation of environment electric capacity in the contact panel.
It is one embodiment of the invention that the electric capacity of Fig. 5 is measured device 50, and this area tool knows that usually the knowledgeable is when doing different variations and modification according to this.Please refer to Figure 11, Figure 11 is the synoptic diagram that the embodiment of the invention one electric capacity is measured device 60.Electric capacity measure device 60 include one-period control circuit 610 and one-period testing circuit 620.Cycle control circuit 610 includes a voltage generation unit 612, discharges and recharges control module 614,616, an analog to digital converter 618 and switch SW 1～SW3, and cycle detection circuit 620 includes an analog to digital converter 622 and a digital signal processing unit 624.Note that analog to digital converter 622 is a N position analog to digital converter, different with the analog to digital converter 522 among Fig. 5, units corresponding is similar in other unit and the electric capacity measurement device 50, does not give unnecessary details at this.
Analog to digital converter 622 is coupled to a testing capacitance 62 and digital signal processing unit 624, is used for the voltage V on the testing capacitance 62
CMBe converted to a N position signal SD, export digital signal processing unit 624 to.The scope of analog to digital converter 622 employed sampling voltages is reference voltage V
LTo a reference voltage V
UBe similar to electric capacity and measure reference voltage V in the device 50
REF3Setting means, measuring device 60 when electric capacity is to fill earlier afterwards to put configuration, above-mentioned sampling voltage scope V
L～V
UMust be greater than to testing capacitance 62 precharge reference voltage V
REF1And analog to digital converter 618 is used for and voltage V
CMReference voltage V relatively
REF2Measuring device 60 when electric capacity is to put earlier afterwards to fill configuration, sampling voltage scope V
L～V
UMust be less than reference voltage V
REF1And reference voltage V
REF2Digital signal processing unit 624 is converted to a count value Dx with signal SD, exports the back-end processing unit to.
Please refer to Figure 12 and Figure 13, Figure 12 and Figure 13 are respectively electric capacity and measure device 60 and be set to fill earlier and afterwards put configuration and put earlier under the situation of afterwards filling configuration, and the sequential chart of coherent signal when discharging and recharging program is wherein described signal S1～S3, voltage V
CMAnd signal SD.In expression signal S3 and voltage V
CMThe time, represent with long dotted line, solid line, short dash line respectively that corresponding to the signal waveform of testing capacitance amount C1, C2, C3 testing capacitance amount size order is C1＜C2＜C3.By Figure 12 and Figure 13 as can be known, the testing capacitance amount represented by the dutycycle of signal SD, so the processing unit that electric capacity is measured device 60 rear ends can be adjusted the charging and discharging capabilities that discharges and recharges control module 614 or 616 according to count value Dx.
Electric capacity in Fig. 5 is measured in the device 50, and the charging ability or the discharge capability that discharge and recharge control module 516 are to be adjusted according to count value Dx by the processing unit 502 of rear end.The present invention proposes another embodiment, order is filled the discharge capability of the electric capacity measurement device of afterwards putting configuration earlier or is put the electric capacity of afterwards filling configuration earlier and measures the charging ability of device directly according to the voltage on the testing capacitance, measure adjustment voluntarily in the device in electric capacity, need not be by the processing unit of rear end.Please refer to Figure 14, Figure 14 is the synoptic diagram that the embodiment of the invention one electric capacity is measured device 70.Electric capacity measure device 70 include one-period control circuit 710 and one-period testing circuit 720.Cycle control circuit 710 includes a voltage generation unit 712, discharges and recharges control module 714,716, an analog to digital converter 718 and switch SW 1～SW3.Cycle detection circuit 720 includes an analog to digital converter 722 and a digital signal processing unit 724.
Note that the different analog to digital converters 718 that are that electric capacity measurement device 70 and electric capacity are measured device 50 are N position analog to digital converters.Analog to digital converter 718 is coupled to a testing capacitance 72 and discharges and recharges control module 716, is used for the voltage V on the testing capacitance 72
CMBe converted to a N position signal SD2, export to and discharge and recharge control module 716.The scope of analog to digital converter 718 employed sampling voltages is a reference voltage V
LTo a reference voltage V
UDischarge and recharge control module 716 according to signal SD2, by 2
NIn the charging ability of individual different brackets or the discharge capability (deciding), select a corresponding charging ability or a discharge capability, testing capacitance 72 is discharged and recharged on the configuration that discharges and recharges control module 716.Compared to Fig. 5, the charging ability or the discharge capability that discharge and recharge control module 716 directly determine according to signal SD2, but not are determined according to the count value that cycle detection circuit 720 is produced by the processing unit of rear end.
It is noted that the binding that discharges and recharges between control module 716 and the testing capacitance 72 is still by switch SW 3 controls, but the signal of gauge tap SW3 is to discharge and recharge the signal S3 that control module 716 is exported, but not the signal SD2 that analog to digital converter 718 is exported.Measure the mode that configuration and setting and the adjustment of back-end processing unit discharge and recharge the charging and discharging capabilities of control module 714 that discharges and recharges of device 70 about electric capacity, please refer to aforementioned electric capacity measuring device 50, do not give unnecessary details at this.
In sum, it is a count value with the voltage transitions on the testing capacitance that electric capacity of the present invention is measured device, and according to the charging and discharging capabilities of count value adjustment to testing capacitance.Therefore, when the environment electric capacity on the contact panel changes because of external factor, or when measuring the contact panel of different qualities, electric capacity of the present invention is measured device and all can be discharged and recharged with suitable charging ability and discharge capability, so measure accurate environment electric capacity.
The above only is the preferred embodiments of the present invention, and all equalizations of doing according to claim of the present invention change and modify, and all should belong to covering scope of the present invention.
Claims (18)
1. an electric capacity is measured device, is used for measuring the electric capacity of a testing capacitance, it is characterized in that this electric capacity measurement device includes:
One charging control unit is used for to this testing capacitance charging;
One discharge control module is used for to this testing capacitance discharge;
One first switch is coupled to this testing capacitance and this charging control unit, is used for controlling the binding between this charging control unit and this testing capacitance according to one first switching signal;
One second switch is coupled to this testing capacitance and this discharge control module, is used for controlling the binding between this discharge control module and this testing capacitance according to a second switch signal;
One first analog to digital converter is coupled to this testing capacitance, and being used for the voltage transitions on this testing capacitance is one first signal; And
One-period testing circuit, be coupled to this testing capacitance, being used for the voltage transitions on this testing capacitance is a count value, exports a processing unit to, this count value is represented the electric capacity of this testing capacitance.
2. electric capacity as claimed in claim 1 is measured device, it is characterized in that this electric capacity measurement device also includes:
One voltage generation unit is coupled to this first analog to digital converter and this cycle detection circuit, is used for producing a plurality of reference voltages, uses for this first analog to digital converter and this cycle detection circuit; And
One the 3rd switch is coupled to this testing capacitance and this voltage generation unit, is used for controlling the binding between this voltage generation unit and this testing capacitance according to one the 3rd switching signal.
3. electric capacity as claimed in claim 2 is measured device, it is characterized in that this voltage generation unit is used for before this charging control unit and this discharge control module discharge and recharge this testing capacitance this testing capacitance being precharged to a predetermined voltage in addition.
4. electric capacity as claimed in claim 3 is measured device, it is characterized in that this predetermined voltage is similar to the employed reference voltage of this first analog to digital converter.
5. electric capacity as claimed in claim 2 is measured device, it is characterized in that the 3rd switching signal is that this processing unit produces.
6. electric capacity as claimed in claim 1 is measured device, it is characterized in that this first analog to digital converter is one 1 analog to digital converters, and other is coupled to this second switch, and this first signal that this first analog to digital converter is produced is this second switch signal.
7. electric capacity as claimed in claim 6 is measured device, it is characterized in that this first switching signal is that this processing unit produces.
8. electric capacity as claimed in claim 1 is measured device, it is characterized in that this first analog to digital converter is one 1 analog to digital converters, and other is coupled to this first switch, and this first signal that this first analog to digital converter is produced is this first switching signal.
9. electric capacity as claimed in claim 8 is measured device, it is characterized in that this second switch signal is that this processing unit produces.
10. electric capacity as claimed in claim 1 is measured device, it is characterized in that this first analog to digital converter is a multidigit analog to digital converter, other is coupled to this discharge control module, and the control module that should discharge is according to this first signal, by selecting a corresponding discharge capability in a plurality of discharge capabilities, in order to this testing capacitance is discharged.
11. electric capacity as claimed in claim 10 is measured device, it is characterized in that this first switching signal is that this processing unit produces, and this second switch signal is that this discharge control module produces.
12. electric capacity as claimed in claim 1 is measured device, it is characterized in that this first analog to digital converter is a multidigit analog to digital converter, other is coupled to this charging control unit, and this charging control unit is according to this first signal, by selecting a corresponding charging ability in a plurality of charging abilities, in order to this testing capacitance is charged.
13. electric capacity as claimed in claim 12 is measured device, it is characterized in that this first switching signal is that this charging control unit produces, and this second switch signal is that this processing unit produces.
14. electric capacity as claimed in claim 1 is measured device, it is characterized in that this cycle detection circuit includes:
One second analog to digital converter is coupled to this testing capacitance, and being used for the voltage transitions on this testing capacitance is a secondary signal; And
One digital signal processing unit is coupled to this second comparer, is used for this secondary signal is converted to this count value.
15. electric capacity as claimed in claim 14 is measured device, it is characterized in that this second analog to digital converter is one 1 analog to digital converters.
16. electric capacity as claimed in claim 14 is measured device, it is characterized in that this second analog to digital converter is a multidigit analog to digital converter.
17. electric capacity as claimed in claim 1 is measured device, it is characterized in that this processing unit is used for adjusting the charging ability of this charging control unit according to this count value.
18. electric capacity as claimed in claim 1 is measured device, it is characterized in that this processing unit is used for adjusting the discharge capability of this discharge control module according to this count value.
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| CN 201010178110 CN102253289B (en) | 2010-05-18 | 2010-05-18 | Electric capacity measuring device for touch control device |
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| CN 201010178110 CN102253289B (en) | 2010-05-18 | 2010-05-18 | Electric capacity measuring device for touch control device |
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| WO2021174428A1 (en) * | 2020-03-03 | 2021-09-10 | 深圳市汇顶科技股份有限公司 | Capacitor detection circuit, sensor, chip, and electronic device |
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