CN103699280A - Capacitance sensing circuit for sensing capacitance change by utilizing charge replication method - Google Patents
Capacitance sensing circuit for sensing capacitance change by utilizing charge replication method Download PDFInfo
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- CN103699280A CN103699280A CN201310627235.9A CN201310627235A CN103699280A CN 103699280 A CN103699280 A CN 103699280A CN 201310627235 A CN201310627235 A CN 201310627235A CN 103699280 A CN103699280 A CN 103699280A
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Abstract
The invention provides a capacitance sensing circuit for sensing capacitance change by utilizing a charge replication method, which comprises at least one capacitor to be detected, an integrating capacitor and a first current mirror with a first current path and a second current path, and the capacitors to be detected can be touched to generate capacitance change. When connected with a circuit between the capacitors to be detected, the first current path generates first current to charge the capacitors to be detected, and meanwhile, the second current path generates second current mapped to the first current to charge the integrating capacitor; consequently, by mapping the charging current on the capacitors to be detected in order to utilize the mapped current to charge the integrating capacitor, the charge energy charged in the capacitors to be detected can be replicated in the integrating capacitor to reflect a voltage signal, and afterward, the capacitance change which is generated when the capacitors to be detected are touched is sensed by detecting the voltage signal.
Description
Technical field
The present invention is relevant for a kind of capacitance sensing circuit, espespecially a kind of capacitance sensing circuit that utilizes electric charge copy mode sense capacitance to change.
Background technology
Consumer electronic device is more prevalent now, and for user is provided operating electronic devices easily, capacitive touch control plate has become the indispensable input operation interface of each consumer electronic device.Electronic installation can be pursuant to the capacitance variations producing when user touches capacitive touch control plate and carry out the detecting of touch point.
Refer to Fig. 1 (a) and Fig. 1 (b), be respectively the electrical block diagram of known capacitance sensing circuit.As shown in the figure, known capacitance sensing circuit 100 is applied in one to be had in the electronic installation of capacitive touch control plate, the capacitance variations that it is produced during by touch-control with charge conversion (charge transfer) mode sense capacitance formula Trackpad.
Because the capacitance variations that testing capacitance 11 touch-controls produce is very small, in order to amplify the capacitance change of testing capacitance 11, capacitance sensing circuit 100 can gauge tap device 13 repeatedly at power supply V
dDor between integrating capacitor 12, carry out switching over action repeatedly,, the energy of a charge of testing capacitance 11 chargings will be transferred among integrating capacitor 12 in multiple times, so that voltage signal VINT can accumulate and amplify.
Continue, refer to Fig. 2, the curve map of the voltage signal producing in integrating capacitor for known capacitance sensing circuit.At this, with C
pAD+ C
iTO=25pF, C
tOUCH=0pF → 1pF, C
iNT=100pF is as the operating conditions of capacitance sensing circuit 100.Capacitive touch control plate by touch-control before, the capacitance of testing capacitance 11 is C
x=25pF carries out charge conversion program repeatedly, to obtain the voltage signal curve 120 before a touch-control between testing capacitance 11 and integrating capacitor 13.Capacitive touch control plate by touch-control after, the capacitance of testing capacitance 11 C that changes
x=25pF → 26pF, the another charge conversion program of carrying out repeatedly between testing capacitance 11 and integrating capacitor 13, to obtain the voltage signal curve 121 after another touch-control.
Due to the testing capacitance (C after touch-control
x=26pF) 11 compared to the testing capacitance (C before touch-control
x=25pF) 11 can fill full more energy of a charge, therefore, and the testing capacitance (C after touch-control
x=26pF) 11 can shift more energy of a charge to integrating capacitor 12, make the current potential of the voltage signal curve 121 after touch-control by the current potential of the voltage signal curve 120 higher than before touch-control.And when the potential difference (PD) between voltage signal curve 120,121 surpasses a preset difference value, electronic installation can be learnt the capacitance variations being produced after capacitive touch control plate is by touch-control by sensing.
Charge conversion mode is mainly to utilize the pressure reduction between testing capacitance 11 and integrating capacitor 12 to carry out electric charge transfer.While carrying out charge conversion program at first, the pressure reduction between testing capacitance 11 and integrating capacitor 12 is maximum, and testing capacitance 11 can provide a larger discharge current I
dfor integrating capacitor 12 chargings, the energy of a charge of testing capacitance 11 can fully be transferred among integrating capacitor 12, voltage signal V
iNTcurrent potential draw high amplitude can be higher.Continue to carry out charge conversion program, the pressure reduction between testing capacitance 11 and integrating capacitor 12 is more and more less, discharge current I
dand then diminish, the energy of a charge of testing capacitance 11 is more and more not easy to be transferred to integrating capacitor 12, causes voltage signal V
iNTcurrent potential to draw high amplitude more and more less.Due to voltage signal V
iNTcurrent potential draw high the factor that amplitude is more and more less, so the charge conversion program that capacitance sensing circuit 100 must be carried out more repeatedly could allow the potential difference (PD) between voltage signal curve 120,121 pull open over preset difference value, to such an extent as to will elongating relatively, is unfavorable for the sensed time going out of capacitance variations the real time operation of touch-control.
Summary of the invention
An object of the present invention, be to provide a kind of capacitance sensing circuit that utilizes electric charge copy mode sense capacitance to change, its circuit comprises that one can touch-control produces the testing capacitance of electric capacitance change, at least one current mirror and an integrating capacitor, current mirror produces a charging current, utilize charging current to charge for testing capacitance, with time current mirror generation one, be mapped in the mapping electric current of charging current, utilize mapping electric current to charge for integrating capacitor, , the energy of a charge of testing capacitance charging via the mapping of current mirror with equity be replicated in integrating capacitor in and on integrating capacitor, reflect a voltage signal, afterwards, the capacitance variations being produced in the time of can sensing testing capacitance by touch-control via detectable voltage signals.
An object of the present invention, be to provide a kind of capacitance sensing circuit that utilizes electric charge copy mode sense capacitance to change, capacitance sensing circuit can be carried out the program that discharges and recharges repeatedly for testing capacitance, utilize electric charge copy mode with by the energy of a charge multiple copies of testing capacitance charging among integrating capacitor, so as to amplifying the voltage signal in integrating capacitor, moreover, while carrying out each time electric charge reproducer, the energy of a charge of testing capacitance charging can intactly be copied among integrating capacitor, so that drawing high amplitude, its current potential of the voltage signal in integrating capacitor can remain fixing consistent.
An object of the present invention, be to provide a kind of capacitance sensing circuit that utilizes electric charge copy mode sense capacitance to change, capacitance sensing circuit can all be replicated in the energy of a charge of the energy of a charge of testing capacitance charging and electric discharge among integrating capacitor, the speed of amplifying so as to the voltage signal of accelerating in integrating capacitor.
An object of the present invention, be to provide a kind of capacitance sensing circuit that utilizes electric charge copy mode sense capacitance to change, its circuit is set up a current source, this current source is parallel to integrating capacitor, utilize current source with by the energy of a charge of stray capacitance composition from the elimination of discharging among integrating capacitor, to obtain one compared with the voltage signal of electronegative potential on integrating capacitor, capacitance sensing circuit can carry out the amplification of more multiplying power so that the capacitance variations that touch control operation produces can be more obvious compared with the voltage signal of electronegative potential for this, so as to increasing the sensitivity on touch-control sensing.
In order to achieve the above object, the invention provides a kind of capacitance sensing circuit that utilizes electric charge copy mode sense capacitance to change, comprising: one first current mirror, comprises one first current path and one second current path; At least one testing capacitance; One integrating capacitor, connects the second current path; One first derailing switch, be connected between testing capacitance and the first current path, when the first derailing switch is closed, circuit between conducting the first current path and testing capacitance, on the first current path, produce one first electric current to charge for testing capacitance, on the second current path, produce one second electric current that is mapped in the first electric current simultaneously, utilize the second electric current to charge for integrating capacitor, cause the energy of a charge and then generation one voltage signal that to copy testing capacitance among integrating capacitor, are charged; An and second switch device, be connected between testing capacitance and ground connection, the first derailing switch and second switch device present reverse switching manipulation, when the first derailing switch is opened and second switch device when closed, disconnect the circuit between the first current path and testing capacitance, circuit between conducting testing capacitance and ground connection, testing capacitance electric discharge.
The present invention provides again a kind of capacitance sensing circuit that utilizes replica current mode sense capacitance to change, comprise: one first current mirror, comprise one first current path and one second current path: one second current mirror, comprises one the 3rd current path and one the 4th current path, one the 3rd current mirror, comprises one the 5th current path and one the 6th current path, and wherein the 4th current path connects the 5th current path, at least one testing capacitance, one integrating capacitor, connects respectively the second current path and the 6th current path, one first derailing switch, be connected between testing capacitance and the first current path, when the first derailing switch is closed, circuit between conducting the first current path and testing capacitance, on the first current path, produce one first electric current with for testing capacitance charging, on the second current path, produce one second electric current that is mapped in the first electric current simultaneously, an and second switch device, be connected between testing capacitance and the 3rd current path, the first derailing switch and second switch device present reverse switching manipulation, when the first derailing switch is opened and second switch device when closed, disconnect the circuit between the first current path and testing capacitance, circuit between conducting testing capacitance and the 3rd current path, testing capacitance discharge generation one flows to the 3rd electric current of the 3rd current path, on the 5th current path and on the 6th current path, produce respectively one the 5th electric current and one the 6th electric current that is mapped in the 3rd electric current, the 5th current direction the 4th current path, the 6th current direction integrating capacitor, wherein, while carrying out testing capacitance charging procedure, select the first derailing switch closure and second switch device to open, utilize the second electric current producing on the second current path to charge for integrating capacitor, cause the energy of a charge and then generation one voltage signal that to copy testing capacitance among integrating capacitor, are charged, or, while carrying out testing capacitance discharge procedures, select the first derailing switch to open and second switch device is closed, utilize the 6th electric current producing on the 6th current path again for integrating capacitor, to charge, cause in integrating capacitor, copy the energy of a charge that testing capacitance discharged and then again accumulate primary voltage signal.
In one embodiment of the invention, wherein the first derailing switch and second switch device are controlled execution switching manipulation repeatedly, to make testing capacitance repeat to discharge and recharge program, after charging procedure each time or after discharge procedures, all in integrating capacitor, accumulate primary voltage signal.
In one embodiment of the invention, wherein capacitance sensing circuit is applied in one and has in the electronic installation of capacitive touch control plate, testing capacitance comprises at least one touch control capacitance and at least one stray capacitance, and after capacitive touch control plate is by touch-control, the electric capacity of touch control capacitance will change.
In one embodiment of the invention, wherein capacitance sensing circuit connects a microcontroller, and microcontroller is obtained capacitive touch control plate from integrating capacitor and changed by the voltage signal being produced before and after touch-control.
In one embodiment of the invention, wherein the first derailing switch and second switch device are controlled execution switching manipulation repeatedly, to make testing capacitance repeat to discharge and recharge program, accumulate primary voltage signal after charging procedure each time in integrating capacitor.
In one embodiment of the invention, wherein the second current path still connects a current source that is parallel to integrating capacitor, and current source is set and is equal to the magnitude of current of distributing to stray capacitance when the first electric current charges for testing capacitance.
Accompanying drawing explanation
The electrical block diagram that Fig. 1 (a) is known capacitance sensing circuit;
Fig. 1 (b) is the another electrical block diagram of known capacitance sensing circuit;
Fig. 2 is the curve map of the voltage signal that produces in integrating capacitor of known capacitance sensing circuit;
Fig. 3 is the structural block schematic diagram of electronic installation of the present invention;
Fig. 4 is the electrical block diagram of capacitance sensing circuit one preferred embodiment of the present invention;
The curve map of the voltage signal that Fig. 5 produces respectively while being the capacitance sensing circuit of Fig. 4 embodiment of the present invention and the operation of the capacitance sensing circuit of known Fig. 1 in integrating capacitor;
Fig. 6 is the electrical block diagram of the another embodiment of capacitance sensing circuit of the present invention;
The curve map of the voltage signal that Fig. 7 produces respectively while being the capacitance sensing circuit of Fig. 4 embodiment of the present invention and the operation of the capacitance sensing circuit of Fig. 6 embodiment in integrating capacitor;
Fig. 8 is the electrical block diagram of the another embodiment of capacitance sensing circuit of the present invention;
The curve map of the voltage signal that Fig. 9 produces respectively while being the capacitance sensing circuit of Fig. 4 embodiment of the present invention and the operation of the capacitance sensing circuit of Fig. 8 embodiment in integrating capacitor;
Figure 10 is the electrical block diagram of the another embodiment of capacitance sensing circuit of the present invention;
The curve map of the voltage signal that Figure 11 produces respectively while being the capacitance sensing circuit of Fig. 4 embodiment of the present invention and the operation of the capacitance sensing circuit of Figure 10 embodiment in integrating capacitor.
Wherein, Reference numeral:
11 testing capacitance 12 integrating capacitors
120 voltage signal curve 121 voltage signal curves
13 derailing switch 200 electronic installations
21 capacitive touch control plate 23 microcontrollers
300 capacitance sensing circuit 301 capacitance sensing circuits
302 capacitance sensing circuit 303 capacitance sensing circuits
31 testing capacitance 311 touch control capacitances
312 stray capacitance 313 stray capacitances
321 first derailing switch 322 second switch devices
33 first current mirror 331 first current paths
332 second current path 34 second current mirrors
341 the 3rd current path 342 the 4th current paths
35 the 3rd current mirror 351 the 5th current paths
352 the 6th current path 36 integrating capacitors
37 current source 360 voltage signal curves
361 voltage signal curve 362 voltage signal curves
363 voltage signal curve 364 voltage signal curves
365 voltage signal curve 366 voltage signal curves
Embodiment
Referring to Fig. 3, is the structural block schematic diagram of electronic installation of the present invention.As shown in the figure, electronic installation 200 of the present invention can be LCD screen, intelligent mobile phone, panel computer, notebook computer, portable electronic devices etc.Electronic installation 200 comprises a capacitive touch control plate 21, a capacitance sensing circuit 300 and a microcontroller 23.Wherein, capacitance sensing circuit 300 connects respectively capacitive touch control plate 21 and microcontroller 23.
When user's touch control capacitance formula Trackpad 21, the electric capacitance change of capacitance sensing circuit 300 in order to produce in sense capacitance formula Trackpad 21, and electric capacitance change is converted to voltage signal V
iNTpresent.Afterwards, microcontroller 23 detectable voltage signals V
iNT, to be pursuant to voltage signal V
iNTand carry out relative touch control operation for electronic installation 200.
Referring to Fig. 4, is the electrical block diagram of capacitance sensing circuit one preferred embodiment of the present invention.As shown in the figure, capacitance sensing circuit 300 comprises at least one testing capacitance (C
x) 31,1 first derailing switch (S
1) 321, one second switch device (S
2) 322,1 first current mirror 33 and an integrating capacitor (C
iNT) 36.
The first current mirror 33 comprises that one first current path 331 and one second current path 332, the first current paths 331 are one to connect into the PMOS transistor M of diode form
1institute forms, and the second current path 332 is another PMOS transistor M
2institute forms.The first derailing switch 321 is connected between testing capacitance 31 and the first current path 331, and second switch device 322 is connected between testing capacitance 31 and ground connection, and integrating capacitor 36 is connected to the second current path 332.Moreover during capacitance sensing circuit 300 actual operation of the present invention, the first derailing switch 321 will present reverse switching manipulation with respect to second switch device 322.
When capacitance sensing circuit 300 is carried out running, first control the first derailing switch 321 closures and second switch device 322 and open, the line conduction that the first current path 331 and testing capacitance are 31, the line broken circuit between testing capacitance 31 and ground connection.On the first current path 331, will produce one first electric current I
1, the first electric current I
1flow to testing capacitance 31 to charge for testing capacitance 31.The same time, on the second current path 332, generation one is mapped in to the first electric current I
1the second electric current I
2, the second electric current I
2flow to integrating capacitor 36 to charge for integrating capacitor 36., the energy of a charge of testing capacitance 31 charging is via the mapping of the first current mirror 33, with equity, is replicated among integrating capacitor 36, and make, reflects a voltage signal V on integrating capacitor 36
iNT.
After testing capacitance 31 full chargings, control the first derailing switch 321 that continues is opened and second switch device 322 closures, the line broken circuit that the first current path 331 and testing capacitance are 31, line conduction between testing capacitance 31 and ground connection, the stored energy of a charge of electric discharge testing capacitance 31, now integrating capacitor 36 can not charged.
After testing capacitance 31 has discharged, control once again the first derailing switch 321 closures and second switch device 322 and open, to continue to carry out charging procedure next time for testing capacitance 32.Control repeatedly the first derailing switch 321 and the 322 execution switching manipulations of second switch device, to repeat to discharge and recharge program for testing capacitance 31.Testing capacitance 31 executes after charging procedure each time, will in integrating capacitor 36, accumulate primary voltage signal V
iNT, so as to amplification voltage signal V
iNT.
Via above-mentioned, capacitance sensing circuit 300 of the present invention by the mode that adopts electric charge and copy (charge clone) the energy of a charge of testing capacitance 31 chargings is copied among integrating capacitor 36,, integrating capacitor 36 is pursuant to the energy of a charge that copies to reflect voltage signal V
iNT.Then, microcontroller 23 is via detecting this voltage signal V
iNTthe capacitance variations that produced can sense testing capacitance 31 by touch-control time of change in voltage.
Refer to Fig. 5, the curve map of the voltage signal producing respectively during for the capacitance sensing circuit of Fig. 4 embodiment of the present invention and the operation of the capacitance sensing circuit of known Fig. 1 in integrating capacitor.At this, with testing capacitance (C
x=25pF) 11/31, integrating capacitor (C
iNT=100pF) 12/36 as operating conditions.As shown in the figure, the energy of a charge that known capacitance sensing circuit 100 adopts charge conversion (charge transfer) mode that testing capacitance 11 is charged is transferred among integrating capacitor 12, after repeatedly electric charge shifts, obtains a voltage signal curve 120.Separately, capacitance sensing circuit of the present invention 300 adopts electric charges to copy the energy of a charge that (charge clone) mode charges testing capacitance 31 and is copied among integrating capacitor 36, after repeatedly electric charge copies, obtains a voltage signal curve 360.
As shown in voltage signal curve 120, well known charge conversion regime is mainly to carry out electric charge transfer by the pressure reduction between testing capacitance 11 and integrating capacitor 12, its pressure reduction between the two can diminish gradually along with the carrying out of electric charge transfer, to such an extent as to the effect that electric charge shifts can be worse and worse,, follow-up while carrying out once again charge conversion program, voltage signal V
iNTcurrent potential to draw high amplitude more and more less.Relative, as shown in voltage signal curve 360, electric charge copy mode of the present invention is mainly the first electric current I on mapping testing capacitance 31
1, the second electric current I that it maps out
2be equal to the first electric current I
1, to such an extent as to the energy of a charge of testing capacitance 31 charging can intactly be copied among integrating capacitor 36,, follow-up while carrying out once again electric charge reproducer, voltage signal V
iNTcurrent potential draw high amplitude and can remain fixing consistent.
At this, capacitance sensing circuit 300 of the present invention adopts electric charge copy mode to adopt charge conversion mode amplification voltage signal VINT rapidly compared to known capacitance sensing circuit 100, and then accelerates the speed of sensing testing capacitance 31 capacitance variations.
Again, in the present invention, testing capacitance 31, except including touch control capacitance 311, still includes many not expected stray capacitances 312,313, and the electric capacity of these stray capacitances 312,313 is often greater than the capacitance change of touch control capacitance 311.When the first electric current I
1during for touch control capacitance 311 charging, the action that the stray capacitance 312,313 that also can be connected in parallel for touch control capacitance 311 is charged simultaneously, to such an extent as to while carrying out electric charge reproducer, the energy of a charge of touch control capacitance 311 and stray capacitance 312,313 all can be copied among integrating capacitor 36 together.In addition, the capacitance change of touch control capacitance 311 is often very small, for the capacitance change of the touch control capacitance 311 that can correctly judge, and generally all can be for voltage signal V
iNTthe action of amplifying.So, for avoiding this to include the voltage signal V of stray capacitance 312,313 compositions
iNTafter being exaggerated, surpass the permissible opereating specification of electronic installation, therefore enlargement ratio will be restricted.In other words, yield in stray capacitance 312,313, electronic installation 200 cannot be for voltage signal V
iNTcarry out the amplification of a larger multiplying power, this is very unfavorable for the capacitance change of sensing touch control capacitance 311.
In view of this, for the energy of a charge of stray capacitance 312,313 compositions is eliminated among integrating capacitor 36, as shown in Figure 6, can among capacitance sensing circuit 301, further be provided with a current source (I
s) 37, this current source 37 is parallel to integrating capacitor 36 to be connected to altogether the second current path 332.Moreover in a preferred embodiment of the present invention, current source 37 is set and is equal to the first electric current I
1during for testing capacitance 31 charging, distribute to the magnitude of current of stray capacitance 312,313.
, as shown in the voltage signal curve 361 of Fig. 7, by the setting of current source 37, the energy of a charge that includes stray capacitance 312,313 compositions in integrating capacitor 36 is via current source 37 elimination of discharging, its voltage signal V
iNTcurrent potential can down reduce because current source 37 carries out the factor of charge discharge, cause to obtain one and do not include stray capacitance 312,313 compositions and there is the voltage signal V compared with electronegative potential
iNT.
At this, the voltage signal V of voltage signal curve 361
iNTvoltage signal V compared to voltage signal curve 360
iNThave compared with electronegative potential, then capacitance sensing circuit 301 for this compared with the voltage signal V of electronegative potential
iNTcan carry out the action that electric charge more repeatedly copies, more obvious to make the capacitance change of touch control capacitance 311 can carry out the amplification of more multiplying power, so as to increasing the sensitivity on touch-control sensing.
Referring to Fig. 8, is the electrical block diagram of the another embodiment of capacitance sensing circuit of the present invention.The capacitance sensing circuit 302 of the present embodiment further includes one second current mirror 3 compared to the capacitance sensing circuit 300 of Fig. 4
4and one the 3rd current mirror 3
5.
Wherein, the second current mirror 34 comprises that one the 3rd current path 341 and one the 4th current path 342, the three current paths 341 are one to connect into the nmos pass transistor M of diode form
3institute forms, and the 4th current path 342 is another nmos pass transistor M
4institute forms.The 3rd current mirror 35 comprises that one the 5th current path 351 and one the 6th current path 352, the five current paths 351 are one to connect into the PMOS transistor M of diode form
5institute forms, and the 6th current path 352 is another PMOS transistor M
6institute forms.
Again, the first derailing switch 321 is connected between testing capacitance 31 and the first current path 331, and second switch device 322 is connected between testing capacitance 31 and the 3rd current path 341.The 4th current path 342 is connected to the 5th current path 351, and integrating capacitor 36 is connected to respectively the second current path 332 and the 6th current path 352.
When capacitance sensing circuit 302 is carried out running, first control the first derailing switch 321 closures and second switch device 322 and open, the line conduction that the first current path 331 and testing capacitance are 31, the line broken circuit that testing capacitance 31 and the 3rd current path are 341.First upper the produced electric current I of the first current path 331
1to flow to testing capacitance 31, to charge for testing capacitance 31.The same time, on the second current path 332, generation one is mapped in to the first electric current I
1the second electric current I
2, the second electric current I
2flow to integrating capacitor 36 to charge for integrating capacitor 36., the energy of a charge of testing capacitance 31 charging is via the mapping of the first current mirror 33, with equity, is replicated among integrating capacitor 36, and make, reflects voltage signal V on integrating capacitor 36
iNT.
After testing capacitance 31 full chargings, control the first derailing switch 321 that continues is opened and second switch device 322 closures, the line broken circuit that the first current path 331 and testing capacitance are 31, the line conduction that testing capacitance 31 and the 3rd current path are 341, now testing capacitance 31 discharge generation 1 the 3rd electric current I
3it flows to the 3rd current path 341.The same time, upper and the 6th current path 352 of the 5th current path 351 upper produces respectively one and is mapped in the 3rd electric current I
3the 5th electric current I
5and the 6th electric current I
6.The 5th electric current I
5flow to the 4th current path 342, and the 6th electric current I
6flow to integrating capacitor 36 to charge for integrating capacitor 36., the energy of a charge of testing capacitance 31 electric discharge is via the mapping of the second current mirror 34 and the 3rd current mirror 35, is replicated among integrating capacitor 36, and makes the upper primary voltage signal V that accumulates once again of integrating capacitor 36 with equity
iNT.
After testing capacitance 31 has discharged, control once again the first derailing switch 321 closures and second switch device 322 and open, to continue to carry out charging procedure next time for testing capacitance 32.Control repeatedly the first derailing switch 321 and the 322 execution switching manipulations of second switch device, to repeat to discharge and recharge program for testing capacitance 31.After testing capacitance 31 executes charging procedure each time or after executing discharge procedures, can in integrating capacitor 36, accumulate primary voltage signal V
iNT, so as to further quickening voltage signal V
iNTthe speed of amplifying.
Refer to Fig. 9, the curve map of the voltage signal producing respectively during for the capacitance sensing circuit of Fig. 4 embodiment of the present invention and the operation of the capacitance sensing circuit of Fig. 8 embodiment in integrating capacitor.At this, with testing capacitance (C
x=25pF → 26pF) 31, integrating capacitor (C
iNT=1000pF) 36 operating conditionss as the capacitance sensing circuit 300 of Fig. 4 embodiment and the capacitance sensing circuit 302 of Fig. 8 embodiment.
When the capacitance sensing circuit 300 of Fig. 4 embodiment is carried out running, the energy of a charge of testing capacitance 31 chargings is replicated among integrating capacitor 36, to obtain (C before a touch-control in integrating capacitor 36
x=25pF) (C after voltage signal curve 362 and a touch-control
x=26pF) voltage signal curve 363.
Separately, when the capacitance sensing circuit 302 of Fig. 8 embodiment is carried out running, except the energy of a charge of testing capacitance 31 charging being copied among integrating capacitor 36, then the energy of a charge of testing capacitance 31 electric discharges is replicated among integrating capacitor 36 in the lump, to obtain (C before a touch-control in integrating capacitor 36
x=25pF) (C after voltage signal curve 364 and a touch-control
x=26pF) voltage signal curve 365.
Using 72mv preset difference value as example is as the base condition that senses the capacitance variations of testing capacitance 31.Through experiment, learn, 302 of the capacitance sensing circuits of Fig. 8 embodiment need running 35us, and the potential difference (PD) that voltage signal curve is 364,365 just can be pulled open over 72mv preset difference value; Relative, the capacitance sensing circuit 300 of Fig. 4 embodiment must operate 55us, and the potential difference (PD) that voltage signal curve is 362,363 just can be pulled open over 72mv preset difference value.
Implement so according to this, among the capacitance sensing circuit 302 of Fig. 8 embodiment can further also be replicated in the energy of a charge of testing capacitance 31 electric discharges integrating capacitor 36 compared to the capacitance sensing circuit 300 of Fig. 4 embodiment, with booster tension signal V more efficiently
iNTthe speed of amplifying, makes the voltage signal V producing on integrating capacitor 36 before and after touch-control
iNTpotential difference (PD) can pull open rapidly, the capacitance variations being produced while causing to make the microcontroller 23 of electronic installation 200 to sense as early as possible capacitive touch control plate 21 by touch-control.
Similarly, in order to eliminate the energy of a charge of stray capacitance 312,313 compositions among integrating capacitor 36, as shown in figure 10, also can among capacitance sensing circuit 303, further be provided with a current source 37, this current source 37 is parallel to integrating capacitor 36 to be connected to altogether the second current path 332 and the 6th current path 352.
, as shown in the voltage signal curve 366 of Figure 11, by the setting of current source 37, the energy of a charge that includes stray capacitance 312,313 compositions in integrating capacitor 36 is via current source 37 elimination of discharging, its voltage signal V
iNTcurrent potential can down reduce because current source 37 carries out the factor of charge discharge, cause to obtain one and do not include stray capacitance 312,313 compositions and there is the voltage signal V compared with electronegative potential
iNT.
At this, the voltage signal V of voltage signal curve 366
iNTvoltage signal V compared to voltage signal curve 360
iNThave compared with electronegative potential, then, capacitance sensing circuit 303 similarly for this compared with the voltage signal V of electronegative potential
iNTcan carry out the action that electric charge more repeatedly copies, more obvious to make the capacitance change of touch control capacitance 311 can carry out the amplification of more multiplying power, so as to increasing the sensitivity on touch-control sensing.
As described above, it is only a preferred embodiment of the present invention, not be used for limiting scope of the invention process, all equalizations of doing according to the shape described in the present patent application the scope of the claims, structure, feature and spirit change and modify, and all should be included in claim of the present invention.
Claims (10)
1. a capacitance sensing circuit that utilizes electric charge copy mode sense capacitance to change, is characterized in that, comprising:
One first current mirror, comprises one first current path and one second current path;
At least one testing capacitance;
One integrating capacitor, connects the second current path;
One first derailing switch, be connected between testing capacitance and the first current path, when the first derailing switch is closed, circuit between conducting the first current path and testing capacitance, on the first current path, produce one first electric current to charge for testing capacitance, on the second current path, produce one second electric current that is mapped in the first electric current simultaneously, utilize the second electric current to charge for integrating capacitor, cause the energy of a charge and then generation one voltage signal that to copy testing capacitance in integrating capacitor, are charged; And
One second switch device, be connected between testing capacitance and ground connection, the first derailing switch and second switch device present reverse switching manipulation, when the first derailing switch is opened and second switch device when closed, disconnect the circuit between the first current path and testing capacitance, circuit between conducting testing capacitance and ground connection, testing capacitance electric discharge.
2. capacitance sensing circuit as claimed in claim 1, it is characterized in that, this capacitance sensing circuit is applied in one to be had in the electronic installation of capacitive touch control plate, this testing capacitance comprises at least one touch control capacitance and at least one stray capacitance, after this capacitive touch control plate is by touch-control, the electric capacity of this touch control capacitance will change.
3. capacitance sensing circuit as claimed in claim 2, is characterized in that, this capacitance sensing circuit connects a microcontroller, and this microcontroller is obtained this capacitive touch control plate from this integrating capacitor and changed by this voltage signal being produced before and after touch-control.
4. capacitance sensing circuit as claimed in claim 1, it is characterized in that, this first derailing switch and this second switch device are controlled execution switching manipulation repeatedly, to make this testing capacitance repeat to discharge and recharge program, accumulate once this voltage signal after charging procedure each time in this integrating capacitor.
5. capacitance sensing circuit as claimed in claim 2, it is characterized in that, this second current path still connects a current source that is parallel to this integrating capacitor, and this current source is set this first electric current of the magnitude of current distribute to this stray capacitance while being equal to to(for) this testing capacitance charging.
6. a capacitance sensing circuit that utilizes replica current mode sense capacitance to change, is characterized in that, comprising:
One first current mirror, comprises one first current path and one second current path:
One second current mirror, comprises one the 3rd current path and one the 4th current path;
One the 3rd current mirror, comprises one the 5th current path and one the 6th current path, and wherein the 4th current path connects the 5th current path;
At least one testing capacitance;
One integrating capacitor, connects respectively the second current path and the 6th current path;
One first derailing switch, be connected between testing capacitance and the first current path, when the first derailing switch is closed, circuit between conducting the first current path and testing capacitance, on the first current path, produce one first electric current with for testing capacitance charging, on the second current path, produce one second electric current that is mapped in the first electric current simultaneously; And
One second switch device, be connected between testing capacitance and the 3rd current path, the first derailing switch and second switch device present reverse switching manipulation, when the first derailing switch is opened and second switch device when closed, disconnect the circuit between the first current path and testing capacitance, circuit between conducting testing capacitance and the 3rd current path, testing capacitance discharge generation one flows to the 3rd electric current of the 3rd current path, on the 5th current path and on the 6th current path, produce respectively one the 5th electric current and one the 6th electric current that is mapped in the 3rd electric current, the 5th current direction the 4th current path, the 6th current direction integrating capacitor, wherein, while carrying out testing capacitance charging procedure, select the first derailing switch closure and second switch device to open, utilize the second electric current producing on the second current path to charge for integrating capacitor, cause the energy of a charge and then generation one voltage signal that to copy testing capacitance among integrating capacitor, are charged, or, while carrying out testing capacitance discharge procedures, select the first derailing switch to open and second switch device is closed, utilize the 6th electric current producing on the 6th current path again for integrating capacitor, to charge, cause among integrating capacitor, copy the energy of a charge that testing capacitance discharged and then again accumulate primary voltage signal.
7. capacitance sensing circuit as claimed in claim 6, it is characterized in that, this capacitance sensing circuit is applied in one to be had in the electronic installation of capacitive touch control plate, this testing capacitance comprises at least one touch control capacitance and at least one stray capacitance, after this capacitive touch control plate is by touch-control, the electric capacity of this touch control capacitance will change.
8. capacitance sensing circuit as claimed in claim 7, is characterized in that, this capacitance sensing circuit connects a microcontroller, and this microcontroller is obtained this capacitive touch control plate from this integrating capacitor and changed by this voltage signal being produced before and after touch-control.
9. capacitance sensing circuit as claimed in claim 6, it is characterized in that, this first derailing switch and this second switch device are controlled execution switching manipulation repeatedly, to make this testing capacitance repeat to discharge and recharge program, after charging procedure each time or after discharge procedures, all in this integrating capacitor, accumulate once this voltage signal.
10. capacitance sensing circuit as claimed in claim 7, it is characterized in that, this second current path still connects a current source that is parallel to this integrating capacitor, and this current source is set this first electric current of the magnitude of current distribute to this stray capacitance while being equal to to(for) this testing capacitance charging.
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106556747A (en) * | 2015-09-25 | 2017-04-05 | 亚德诺半导体集团 | Capacitance measurement |
| CN109073692A (en) * | 2018-07-20 | 2018-12-21 | 深圳市汇顶科技股份有限公司 | Capacitive detection circuit, touch detecting apparatus and terminal device |
| CN111434001A (en) * | 2017-12-30 | 2020-07-17 | 德州仪器公司 | Capacitor balancing driver circuit for dual input charger |
| CN111434001B (en) * | 2017-12-30 | 2024-04-26 | 德州仪器公司 | Capacitor balanced driver circuit for dual input charger |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101833406A (en) * | 2010-03-30 | 2010-09-15 | 福建华映显示科技有限公司 | Touch panel detection circuit |
| US20110148440A1 (en) * | 2008-10-15 | 2011-06-23 | Frederick Johannes Bruwer | Parasitic capacitance cancellation in capacitive measurement applications |
| CN102253771A (en) * | 2010-05-20 | 2011-11-23 | 义隆电子股份有限公司 | Sensing unit, sensing circuit and sensing method for capacitive touch panel |
| CN102346607A (en) * | 2010-08-05 | 2012-02-08 | 义隆电子股份有限公司 | Touch control sensing circuit and method |
| CN103376965A (en) * | 2012-04-12 | 2013-10-30 | 爱特梅尔公司 | Method and apparatus for current mirror self-capacitance measurement |
-
2013
- 2013-11-28 CN CN201310627235.9A patent/CN103699280A/en active Pending
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20110148440A1 (en) * | 2008-10-15 | 2011-06-23 | Frederick Johannes Bruwer | Parasitic capacitance cancellation in capacitive measurement applications |
| CN101833406A (en) * | 2010-03-30 | 2010-09-15 | 福建华映显示科技有限公司 | Touch panel detection circuit |
| CN102253771A (en) * | 2010-05-20 | 2011-11-23 | 义隆电子股份有限公司 | Sensing unit, sensing circuit and sensing method for capacitive touch panel |
| CN102346607A (en) * | 2010-08-05 | 2012-02-08 | 义隆电子股份有限公司 | Touch control sensing circuit and method |
| CN103376965A (en) * | 2012-04-12 | 2013-10-30 | 爱特梅尔公司 | Method and apparatus for current mirror self-capacitance measurement |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106556747A (en) * | 2015-09-25 | 2017-04-05 | 亚德诺半导体集团 | Capacitance measurement |
| CN111434001A (en) * | 2017-12-30 | 2020-07-17 | 德州仪器公司 | Capacitor balancing driver circuit for dual input charger |
| CN111434001B (en) * | 2017-12-30 | 2024-04-26 | 德州仪器公司 | Capacitor balanced driver circuit for dual input charger |
| CN109073692A (en) * | 2018-07-20 | 2018-12-21 | 深圳市汇顶科技股份有限公司 | Capacitive detection circuit, touch detecting apparatus and terminal device |
| WO2020014977A1 (en) * | 2018-07-20 | 2020-01-23 | 深圳市汇顶科技股份有限公司 | Capacitance detection circuit, touch detection apparatus and terminal device |
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