WO2010036545A2 - Mutual capacitance measuring circuits and methods - Google Patents
Mutual capacitance measuring circuits and methods Download PDFInfo
- Publication number
- WO2010036545A2 WO2010036545A2 PCT/US2009/057114 US2009057114W WO2010036545A2 WO 2010036545 A2 WO2010036545 A2 WO 2010036545A2 US 2009057114 W US2009057114 W US 2009057114W WO 2010036545 A2 WO2010036545 A2 WO 2010036545A2
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- electrode
- voltage
- capacitance
- circuit
- array
- Prior art date
Links
Classifications
-
- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F3/00—Input arrangements for transferring data to be processed into a form capable of being handled by the computer; Output arrangements for transferring data from processing unit to output unit, e.g. interface arrangements
- G06F3/01—Input arrangements or combined input and output arrangements for interaction between user and computer
- G06F3/03—Arrangements for converting the position or the displacement of a member into a coded form
- G06F3/041—Digitisers, e.g. for touch screens or touch pads, characterised by the transducing means
- G06F3/044—Digitisers, e.g. for touch screens or touch pads, characterised by the transducing means by capacitive means
- G06F3/0446—Digitisers, e.g. for touch screens or touch pads, characterised by the transducing means by capacitive means using a grid-like structure of electrodes in at least two directions, e.g. using row and column electrodes
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R27/00—Arrangements for measuring resistance, reactance, impedance, or electric characteristics derived therefrom
- G01R27/02—Measuring real or complex resistance, reactance, impedance, or other two-pole characteristics derived therefrom, e.g. time constant
- G01R27/26—Measuring inductance or capacitance; Measuring quality factor, e.g. by using the resonance method; Measuring loss factor; Measuring dielectric constants ; Measuring impedance or related variables
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
- G01R19/02—Measuring effective values, i.e. root-mean-square values
-
- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F3/00—Input arrangements for transferring data to be processed into a form capable of being handled by the computer; Output arrangements for transferring data from processing unit to output unit, e.g. interface arrangements
- G06F3/01—Input arrangements or combined input and output arrangements for interaction between user and computer
- G06F3/03—Arrangements for converting the position or the displacement of a member into a coded form
- G06F3/041—Digitisers, e.g. for touch screens or touch pads, characterised by the transducing means
- G06F3/0416—Control or interface arrangements specially adapted for digitisers
- G06F3/04166—Details of scanning methods, e.g. sampling time, grouping of sub areas or time sharing with display driving
Definitions
- the present invention relates generally to capacitance measuring circuits and methods, and to systems such as capacitive touch sensing systems that utilize capacitance measuring circuits and methods.
- Touch sensitive devices allow a user to conveniently interface with electronic systems and displays by reducing or eliminating the need for mechanical buttons, keypads, keyboards, and pointing devices. For example, a user can carry out a complicated sequence of instructions by simply touching an on-display touch screen at a location identified by an icon.
- Capacitive touch sensing devices have been found to work well in a number of applications.
- the input is sensed when a conductive object in the sensor is capacitive Iy coupled to a conductive touch implement such as a user's finger.
- a conductive touch implement such as a user's finger.
- capacitive touch sensitive device as an object such as a finger approaches the touch sensing surface, a tiny capacitance forms between the object and the sensing points in close proximity to the object.
- the sensing circuit can recognize multiple objects and determine the characteristics of the object as it is moved across the touch surface (such as location, pressure, direction, speed, acceleration, and so forth).
- One aspect of the present disclosure concerns a switched capacitor capacitive controller that measures mutual capacitance and/or capacitance to ground to determine touch locations, and methods of operating a controller to measure mutual capacitance, capacitance to ground, and/or ratios of capacitance.
- the present disclosure is generally directed to capacitance measuring circuits that measure capacitance between electrodes and capacitance of electrodes to ground, in which the charging and discharging of capacitors can be performed using a series of switch- controlled cycles during which voltage signals are applied to at least one driven electrode, and the signals are measured on at least one measured electrode.
- an apparatus is provided for measuring a parameter related to the capacitance between a drive electrode and a receive electrode of a touch sensitive device.
- the apparatus includes an accumulator capacitor coupled at one end to a voltage measurement circuit and at the other end to the receive electrode, and control circuitry configured and arranged, during each cycle of a measurement sequence, to connect a reference voltage to a first node that electrically connects the accumulator capacitor to the voltage measurement circuit.
- the apparatus further includes a resistive circuit configured and arranged to draw current from a second node electrically connected to the accumulator capacitor and to the receive electrode during the measurement sequence.
- Some embodiments of the present disclosure are further related to measuring the number of voltage transition cycles required to accumulate charge to a level established by a comparator threshold.
- the switching and comparator functions can be accomplished using standard parallel input/output logic circuits, and the resistance and charge accumulation functions can be accomplished using low cost, readily obtained components.
- the present disclosure also provides capacitance measuring circuits and methods that may apply voltages to switching elements that time- average to zero over an extended time, which can improve linearity of measurements and reduce sensitivity of measurements to parasitic capacitance.
- the present disclosure also provides capacitance measuring circuits and methods that may apply voltages to electrodes that time-average to zero over an extended time.
- the present disclosure also provides capacitance measuring circuits and methods that may apply simultaneous voltages of different phase to multiple driven electrodes, and measure differences in capacitance between two or more driven electrodes and one or more receiver electrodes.
- the present disclosure also provides capacitance measuring circuits and methods that may apply voltage to two or more electrodes of a first array and measure changes in capacitance among two or more electrodes of a second array, then resolve touched electrodes of the second array, then apply voltage sequentially to touched electrodes of the second array and measure differences in capacitance among two or more electrodes of a first array, thereby resolving touch locations at all intersections of the first array and the second array in a minimum number of measurements.
- the present disclosure can provide enhanced capacitance measuring circuits at a low cost and that are easily integrated into standard logic circuits, microprocessors, gate arrays, or application specific integrated controllers (ASICs).
- ASICs application specific integrated controllers
- Fig. 1 is a circuit for measuring mutual capacitance between two electrodes in proximity.
- Fig. 2 is a circuit for measuring mutual capacitance between four driven electrodes and four receiver electrodes in proximity.
- Fig. 3a is block diagram of an apparatus for measuring mutual capacitance.
- Fig. 3b is a circuit for measuring mutual capacitance between electrodes.
- Fig. 4a is a graph showing simulated waveforms of an embodiment of the invention.
- Fig. 4b is a graph showing simulated waveforms of an embodiment of the invention.
- Fig. 5 shows a circuit for measuring mutual capacitance between electrodes.
- Fig. 6 shows a circuit for measuring mutual capacitance between electrodes.
- Fig. 7 is a graph showing simulated waveforms of an embodiment of the invention.
- Fig. 8 is a graph showing simulated waveforms of an embodiment of the invention.
- Fig. 9 is a circuit for measuring mutual capacitance among electrodes using multiple driven signals with different phases.
- Fig. 10a is a circuit for measuring mutual capacitance between electrodes and for measuring a ratio of mutual capacitance to capacitance-to-ground of electrodes.
- Fig. 10b is a circuit for measuring mutual capacitance between electrodes and for measuring a ratio of mutual capacitance to capacitance-to-ground of electrodes.
- Fig. 1OC is a circuit for measuring mutual capacitance between electrodes and for measuring a ratio of mutual capacitance to capacitance-to-ground of electrodes and for measuring mutual capacitance between an array of electrodes and a stylus electrode.
- Fig. 11 is a circuit for measuring capacitance-to-ground of electrodes.
- aspects of the present disclosure are generally directed to capacitance measuring circuits that measure capacitance between electrodes and capacitance of electrodes to ground, in which the charging and discharging of capacitors are performed using a series of switch-controlled cycles during which voltage signals are applied to at least one driven electrode, and the signals are measured on at least one measured electrode.
- a touch is near proximity of a conductive element which may be a finger, metal object, stylus, or other conductive material. Finger(s) or conductive object(s) used in a touch are connected to ground by a capacitance and/or resistance (typically hundreds to thousands of picofarads) unless otherwise stated.
- Electrode is an electrically conductive object that may be activated with electrical signals, resulting in electric fields that are sensitive to proximity of a touch.
- IO or I/O means Input/Output, such as an I/O device which is a device capable of receiving input electrical signals and sending output electrical signals.
- I/O device which is a device capable of receiving input electrical signals and sending output electrical signals.
- t represents the transition of an electrical signal from a voltage to a more positive voltage.
- J represents the transition of an electrical signal from a voltage to a more negative voltage.
- ADC or A/D converter is a device that converts an electrical signal to a digital form ("analog/digital converter"). For example, a voltage may be converted to a binary number that represents the voltage.
- ADC methods include successive approximation, timed slope converters, dual slope converters, sigma-delta converters, voltage comparators including logic gates, and other methods known in the art.
- DAC or D/A converter is a device that converts a digital value to an electrical signal ("digital/analog converter"). For example, a 16 byte binary number may be converted to an analog voltage.
- Ground refers to a common electrical reference point which may be at the voltage of earth ground, or may be a local common voltage.
- Some embodiments of the present disclosure are further related to measurements that are performed in a bipolar manner, that is, by measuring the capacitance between electrodes with current flowing from a first electrode Pl to a second electrode P2 and also with current flowing from second electrode P2 to first electrode Pl . Certain embodiments employing bipolar measurements may reduce susceptibility to low frequency noise.
- Some embodiments of the present disclosure are further related to measuring the number of voltage transition cycles required to accumulate charge to a level established by a comparator threshold.
- the switching and comparator functions can be accomplished using standard parallel input/output logic circuits, and the resistance and charge accumulation functions can be accomplished using low cost, readily obtained components.
- the present disclosure also provides capacitance measuring circuits and methods that may apply voltages to switching elements that time-average to zero over an extended time, which can improve linearity of measurements and reduce sensitivity of measurements to parasitic capacitance. In certain embodiments, the present disclosure also provides capacitance measuring circuits and methods that may apply voltages to electrodes that time-average to zero over an extended time.
- the present disclosure also provides capacitance measuring circuits and methods that may apply simultaneous voltages of different phase to multiple driven electrodes, and measure differences in capacitance between two or more driven electrodes and one or more receiver electrodes.
- the present disclosure also provides capacitance measuring circuits and methods that may apply voltage to two or more electrodes of a first array and measure changes in capacitance among two or more electrodes of a second array, then resolve touched electrodes of the second array, then apply voltage sequentially to touched electrodes of the second array and measure differences in capacitance among two or more electrodes of a first array, thereby resolving touch locations at all intersections of the first array and the second array in a minimum number of measurements .
- Fig. 1 shows a simplified schematic of a device 10 for measuring mutual capacitance Cm between two electrodes 12 and 13.
- Measurement circuitry 18 and drive circuitry 19 are connected to receiver electrode 12 and driven electrode 13 and are used to measure Cm.
- Devices for measuring capacitance can take the form of capacitive input (for example, touch) devices such as buttons and switches, linear sliders, and matrix touch panels, as well as sensors for detecting the presence or amount of a substance positioned proximate the electrode, or a digitizer for capacitive detection of a stylus.
- At least one unknown mutual capacitance results from coupling between electrodes
- second and third unknown capacitances results from coupling between driven electrode Cr and ground
- receive electrode Cr and ground At least one unknown mutual capacitance
- Cm, Cd and Cr change when an object or substance comes into proximity with the electric field generated when AC voltages are applied to at least one of the electrodes. This change may be used as a basis for identifying a touch or the presence of an object.
- the present disclosure provides circuitry and methods for measuring parameters of these capacitances including a ratio of Cm and Cr, and the value of Cm and Cr.
- FIG. 2 shows a simplified schematic of a device 20 for measuring locations of a touching object (for example, touches to points Tl, T2, and T3).
- electrodes Da - Dd have capacitances to ground Cda - Cdd respectively and receive electrodes Rcvl - Rcv4 have capacitances to ground CrI - Cr4 respectively.
- Capacitances Cda - Cdd and CrI - Cr4 change when a touching object is in proximity. Capacitances to ground of measured electrodes can be measured by the methods disclosed herein.
- Inter-electrode (mutual) capacitances CmIa - Cm4d can be measured by the methods disclosed herein. Touch locations are resolved (located) by measuring changes in capacitances Cm, and in some embodiments, changes in capacitance to ground are also used to resolve touch location.
- Receive circuits 25, 26, 27, and 28 accumulate and measure signals on receiver electrodes CrI - Cr4 respectively, under the control of controller 29. Circuits 35, 105, and 95 in Fig. 3b, Fig. 10b and Fig. 10a respectively show more detail of receive circuit embodiments.
- Drive circuits 21, 22, 23, and 24 apply signals to electrodes Da, Db, Dc, and Dd respectively under the control of controller 29. In some embodiments, such as circuit 92, Fig.
- circuits 21 - 28 may be switched between drive and receive functions, so in one mode Cda - Cdd are driven while CrI - Cr4 receive, then in another mode CrI - Cr4 are driven while Cda - Cdd receive signals.
- Example touches Tl, T2, and T3 are shown as directly on electrode intersections, affecting only one touched electrode. This is for illustration purposes only; with typical matrix touch screens, a single touch will affect capacitance and signals on two or more adjacent electrodes, and interpolation methods are used to resolve touch locations with finer resolution than the spacing of electrodes. Where interpolation is required or deemed beneficial, additional measurements of Cm (for example, steps 3 and 4 of Algorithm 3, discussed below) may be performed on electrodes adjacent to touched electrodes that were detected in step 1 of the algorithm.
- Fig. 3a is block diagram of an apparatus 300 for measuring mutual capacitance according to an example embodiment of the present invention.
- the apparatus measures the capacitance between a drive electrode 301 and a receive electrode 302 of a touch sensitive device 303.
- the apparatus includes a capacitor-based circuit 304 coupled at one end to a voltage measurement circuit 305 and at the other end to the receive electrode 302.
- the apparatus also includes control circuitry 306 configured and arranged, at the beginning of each cycle of a measurement sequence, to connect a reference voltage 307 to a first node 310 that electrically connects the accumulator capacitor 304 to the voltage measurement circuit 305.
- the measurement sequence is used to discern and/or resolve apparent touches on the touch sensitive device 303.
- the drive electrode 301 is driven with a pulse voltage 309 that has cycles corresponding to the cycles of the measurement sequence.
- the capacitor-based circuit 304 accumulates an increasing amount of charge during each of the cycles of the measurement sequence.
- the control circuitry 306 is configured to count the number of cycles that it takes for the voltage at the first node 310 to exceed the threshold voltage of the voltage measurement circuit 305.
- the apparatus further includes a resistive circuit 308 configured and arranged to draw current from a second node 311 electrically connected to the capacitor-based circuit 304 and to the receive electrode 302 during the measurement sequence.
- FIG. 3b shows a simplified schematic of touch system 30 that measures mutual capacitance Cm between driven electrode Pl and receiver electrode P2 of sensor 31 , and Cr.
- P 1 and P2 may be components of a transparent matrix touch sensor where P 1 is one of many lower electrodes and P2 is one of many upper electrodes.
- Cm, Cd, and Cr are shown as variable capacitors because their values change when in proximity with a touching object.
- V2 is more positive than Vl .
- Driver Dl applies voltage V6 to electrode Pl.
- Dl may comprise a pair of switches
- V2 alternately connecting electrode Pl to Vl, then V2.
- Reference resistor Rrefl connects electrode P2 to reference Vref, which in some embodiments is ground (OV) and in other embodiments is a variable voltage.
- the transition of voltage V6 occurs during the time that switch S4 is closed, and it is preferable that the rate of transitions of V6 have a controlled rate. It is generally preferable that signal V6 be large as possible to maximize the signal to noise ratio (S/N) of measurements.
- V2 may be greater than V4, and/or Dl may incorporate a capacitor charge pump and/or a magnetic fly-back circuit so peak levels and voltage transitions of V6 can be larger than (V2-V1).
- Driver Dl may further incorporate circuits to measure current Il that flows to driven electrode Pl .
- Exemplary methods of measuring Il include those disclosed in US Patent Application Publication No. 2008/0142281.
- Current ll is proportional to the total capacitance between Pl and its environment (Cm and Cd).
- a touch (not shown) proximate to Pl and P2 will reduce mutual capacitance Cm and it will also increase capacitances-to-Gnd Cd and Cr.
- Receive circuit 35 includes accumulator capacitor Cl, reference resistor Rrefl, demodulator switch S4, and measurement circuit Ml .
- Ml has high input impedance and low input leakage current.
- Ml is a comparator or logic gate, as shown, for example, in Fig. 5 and Fig. 6.
- Ml may be an analog to digital converter (ADC).
- Controller Fl includes logic used to control the operation of voltage signal driver Dl and switch S4 and measurement circuit Ml.
- Another example embodiment of the present invention is shown in Fig. 5.
- an illustrated circuit 1 has a fixed reference voltage (Vref) that accumulates charge on capacitor Cl until voltage VlO exceeds the threshold voltage of measurement circuit Ml
- Exemplary circuit 1 is based on system 30 from Fig. 3b and, therefore, includes component designations that match those of corresponding components in System 30, with the exception of components within perimeter 40, (e.g., Al, A2, A3,
- Pulse 11, Pulse 12 and R2 which generate drive pulse V6 and timing pulses for S4 and the clock of measurement circuit (latch) Ml.
- Simulation of this circuit 1, as well as later discussed in connection with circuits 2, 3, and 4 (Figs 6, 9, and 11 respectively) can be achieved with a program marketed under the trade name "LT spice IV" available from Linear Technology Corporation of Milpitas, California.
- Circuit 1 simulates two electrodes (Pl, P2) with capacitances to ground Cd and Cr, and mutual capacitance Cm. Reference voltage nodes are labeled. Parameters of Circuit 1 are on the schematic, and as shown below:
- Vth 1.5 V (switching threshold of M 1 )
- V6 15.0V
- Pulse (0 10 0.25u 0 0 0.5u lOu) represents:
- System 30 from Fig. 3b may be operated according to Measurement Sequence 1, shown in Table 1.
- Measurement Sequence 1 driver Dl generates an AC wave V6 that drives electrode Pl .
- Transitions in voltage V6 on driven electrode Pl cause electrical charge to flow through mutual capacitance Cm to receiver electrode P2.
- a (preferably small) portion of charge Q3 flows through parasitic capacitance Cr, and the other portion flows to accumulator capacitor Cl .
- Current into capacitance Cd has negligible effect on measurements. Charge from either positive (+) or negative (-) transitions of V6 may be measured during a measurement sequence.
- the voltage across Rrefl, (V8-Vref) discharges to near Vref before VlO is measured.
- an ADC measurement is made after a specific number of measurement cycles are executed.
- V6 remains positive for about 9 uSec in this example.
- This settling time may vary widely depending on capacitance magnitudes, accuracy requirements, noise, and measurement time constraints, but preferably longer than several ⁇ 2 to allow voltages V8 and VlO to settle to a stable value.
- Fig. 4b shows the waveforms of a complete Measurement Sequence resulting from the simulation of Circuit 1.
- Fig. 4a shows more detailed waveforms of several Measurement Cycles of Circuit 1. Magnitudes of waveforms in Fig. 4a are not to scale. V(S4) and V6 are reduced in magnitude from 10V and 15V respectively for illustration purposes.
- the sample time is preferably minimized to include the duration of negative transitions of V6 only.
- the preference for short Sample times and relatively long ⁇ 2 settling times leads to a preferred V6 waveform with short-duration negative pulses and longer duration positive pulses as shown in Figs. 4a and 4b.
- V6 is the peak-to-peak magnitude of the drive pulse V6 (Fig. 3b) (or V96, which will be discussed in reference to Fig. 10, below).
- the measurement can be sensitive to touch because a touch to Pl and P2 reduces Cm and also increases Cr, meaning, in the presence of a touch, a higher number of cycles are needed to raise C 1 to the threshold voltage (as compared with the number of cycles needed to raise Cl to the threshold voltage in the absence of a touch).
- the ratio in Equation 1 combines both changes for maximum effect. Changes in Cr only can also be measured, so the ratio can also be effective in resolving multiple touches to a matrix touch sensor with multiple X and Y electrodes. Also, where a single driven electrode is being used with one or more receive electrodes, the ratio measurement may be sufficient to measure and discriminate one or more touch locations.
- using a measurement sensor with multiple driven electrodes can be implemented as shown in Fig. 2.
- This example embodiment uses an algorithm to resolve multiple touches.
- the algorithm can assume, for example, that driven electrodes Da - Dd are driven sequentially.
- a touch to point Tl will reduce the measured level of measurement circuit 26 for each electrode that is driven, due to the increase in capacitance to ground (Cr2) of touched electrode Rcv2.
- the measured level at 26 will be reduced by a larger amount when electrode Db is being driven, because Cni2b is reduced in addition to Cr2 being increased for this specific measurement.
- a second touch T2 results in reduced measured signals on electrodes Rcv2 and Rcv4, for every driven electrode.
- Equation 1 the ratio measurement of Equation 1 and a simple algorithm based on relative magnitudes of signal changes can be used to uniquely resolve a touch location or multiple touch locations on a sensor with intersecting electrodes.
- Example touches Tl, T2, and T3 are shown as directly on electrode intersections, affecting only one touched electrode. This is for illustration purposes only; with typical matrix touch screens, a single touch will affect capacitance and signals on two or more adjacent electrodes, and interpolation methods are used to resolve touch locations with finer resolution than the spacing of electrodes. Interpolation methods known in the art may be applied to measured signals described with respect to all embodiments herein to achieve high touch resolution.
- mutual capacitance is measured using a fixed reference voltage Vref for a fixed number of samples and then ramping the threshold voltage.
- the threshold voltage can be ramped as illustrated in Fig. 6 via circuit 2, as another simulation circuit based on system 30 of Fig. 3b (also using similar component designations in circuit 1, with the exception of components within perimeter 41, (Al, A2, A3, Pulse21, Pulse22, R9) which generate drive pulse V6 and timing pulses).
- Circuit 2 is similar to circuit 1, while mutual capacitance Cm is lpf rather than 3pf and Vref is a variable voltage rather than Gnd.
- Fig. 7 shows exemplary waveforms as circuit 2 (Fig. 6) performs a fixed number
- V6 pulses to charge accumulator cap Cl to a voltage Vf, which is near its maximum voltage level.
- Vref is constant 0.0V.
- S4 is open, a counter is clocked at a fixed rate, and Vrefl ramps positive at a known reference rate until VlO crosses the input threshold of A4 and Vth changes state. When Vth changes, the counter state is stored.
- Vf Vth - (Vth- Vf).
- a single reference voltage can be used with (single or) multiple measurement circuits to perform multiple simultaneous measurements.
- Figs. 7 and 8 show signal ramps during ADC cycles. These ramps may be continuous slopes or incremental discrete steps generated by, for example, a pulse generator or a DAC.
- Fig. 7 shows a simple ADC ramp starting at 500uSec, and ramping at a fixed rate until Vth is reached.
- An alternative ADC waveform may be used to reduce the ramp time during ADC measurements by stepping Vref by a large increment at the beginning of an ADC cycle, (but not enough for any channels to reach Vth). Then Vref is ramped at a fixed rate for the remaining distance until all channels have crossed Vth.
- the ADC cycle could be started by stepping Vref +0.5 volts at 500uSec, then ramping at the rate shown in Fig. 7. This step-and-ramp ADC method can be used with various embodiments disclosed herein).
- the circuit 2 of Fig. 6 may be operated in another mode, as shown in Fig. 8, which shows exemplary waveforms as circuit 2 performs a fixed number N of V6 pulses to charge accumulator cap Cl to a voltage VO, while simultaneously ramping Vref negative at a constant rate RaI that maintains VlO near 0.0V.
- N pulses V6 stops pulsing
- S4 is open
- a counter is clocked at a fixed rate
- Vref ramps positive at a known reference rate Ra2 until VlO crosses the input threshold of A4 and Vth changes state.
- Vth changes the counter is stopped.
- the count is related to the voltage on accumulator cap Cl which is proportional to (Vth-VO).
- VO may be calculated from the stored count, using Equation 2.
- Vref is fixed during sampling time, V8 averages 0.0 V, and VlO ramps exponentially to a limit related to the ratio of Cm and Cr, as discussed with respect to Equation 1. As VlO increases, an increasing portion of the charge on Cl is returned to Cr and Cm each time S4 closes, causing V8 to pulse negative.
- Vref changes at a constant rate that keeps VlO near 0.0V even when S4 is open.
- node N2 becomes a summing junction under the control of Fl.
- Negative transitions of V8 during S4 closure are reduced to near zero so negligible net current flows through Cr.
- VlO is minimally affected by changes in Cr due to a touch, so VlO is substantially proportional to mutual capacitance Cm, independent of Cr or Cd (as demonstrated in Table 3).
- Fig. 8 shows VlO is also more linear than VlO shown in Fig. 4b, and resolution of measurements can be increased by sampling for a longer period of time, limited only by the voltage range of Vref.
- Vref ramp rate can be adjusted such that VlO settles to near zero at the end of each measurement cycle (as shown in Fig. 8) during the period from OmSec to lmSec.
- Vref ramp rate is under the control of controller Fl.
- controller Fl may measure VlO and adjust Vref sampling ramp rate such that VlO is near 0.0V. If many receive circuits are connected to a single Vref, all are tested and Vref is adjusted so the average voltage is zero. Subsequently when a touch occurs, capacitances Cm and Cr change by relatively small amounts in the range of 5% to 20%. This change is small enough that linearity remains good, and sensitivity to changes in Cr remains low.
- Inter-electrode mutual capacitances in a given sensor are generally near-equal in magnitude. Capacitances to ground of the receive electrodes (or driven electrodes) are also very similar in magnitude.
- Receive circuits 25 - 28 may be implemented with four of circuits 35 (Fig. 3b). Where a single Vref drives many measurement channels as in Fig. 2, Vref can be adjusted so the average of all VlOs is zero. This will generally yield near-zero voltages at the switches of receive circuits 25, 26, 27, and 28 during measurement cycles because Cm's (and Cr' s) of a matrix sensor are typically approximately equal. In a typical system of this type, the change to any VlO caused by touching a Cm and/or a Cr is sufficiently small that Vref need not be re-adjusted for each touch.
- Fig. 9 shows Circuit 3, a variation of Circuit 2 (Fig. 6) simulation whereby two electrodes are driven simultaneously with pulses of opposite phase.
- Component designations in Circuit 3 match those of corresponding components in system 30 (Fig. 3b), with the exception of components within perimeter 43, (Al, A2, A3, Pulse41, Pulse42, Rl, R2) which generate timing pulses, drive pulse V6, and opposite-polarity drive pulse V7 which drives a second driven electrode PI l.
- Circuit 3 performs a measurement sequence with a fixed number N of simultaneous V6 and V7 pulses for a period, for example, 1 mSec. During (-) transitions of V6 and (+) transitions of V7, S4 is closed.
- S4 is opened and VlO ramps positive at a reference rate and a timer measures the time to cross a threshold voltage, as discussed previously.
- a measurement sequence may be performed with S4 closed during (+) transitions of V6 and (-) transitions of V7.
- VlO may be controlled within the desired range by several methods: • Vref may be varied during measurement cycles to maintain positive voltage.
- Vref may be set to a fixed (preferably small) positive voltage during measurement cycles.
- S4 may be closed for a period of time before each measurement sequence as described with respect to Step NO of Measurement Sequence 1.
- a measurement sequences may be performed with sampling switch S4 closed during (-) transitions of V6 and (+) transitions of V7, then a second Measurement Sequence may be performed with S4 closed during (+) transitions of V6 and (-) transitions of V7.
- Circuit 3 is relatively insensitive to changes in Cr providing minimal voltage accumulates on accumulator capacitors (Cl, etc.), so voltages V8 and VlO are near zero.
- low frequency noise may be reduced by driving pairs of electrodes with opposite-phase signals and alternating between two Measurement Sequences 1 and 2.
- sampling switches (e.g., S4) of measurement circuits are closed during (-) transitions of voltage (e.g., V6) on a first electrode and (+) transitions of voltage (e.g., V7) on a second electrode, then during Measurement Sequence 2 sampling switches (S4) of measurement circuits are closed during (+) transitions of voltage (e.g., V6) on a first electrode and (-) transitions of voltage (e.g., V7) on a second electrode.
- the method may include performing the following exemplary algorithm, (described with respect to Fig. 2): 1. Apply signals Va and Vc of equal magnitude and opposite phase to a first driven electrode Da and a second electrode Dc respectively (more than one pair of opposite-phase signals may be applied at one time).
- Receive channels measure signals on all receive electrodes by performing a first Measurement Sequence wherein negative signal transitions applied to a first electrode and simultaneous positive signal transitions applied to a second electrode are measured during each sample time.
- the signals sampled by measurement circuits 25 - 28 will all accumulate to ⁇ 0 with no touch applied.
- the opposite signals are preferably applied to electrodes that are spaced apart by sufficient distance that a touch to the first electrode will not affect signals on the second electrode.
- More than one pair of electrodes may be driven simultaneously and at opposite phases.
- a first adjacent pair of electrodes may be ramped positive while a second adjacent pair of electrodes (preferably spaced apart from the first pair) are ramped negative.
- a first non-adjacent pair of electrodes may be ramped positive while a second non-adjacent pair of electrodes are ramped negative, where all four electrodes are spaced apart from one another.
- a first benefit is that the settling time of each measurement cycle can be reduced, or resistance increased.
- the R-C time constant of the reference resistor (Rref) and capacitance of the attached electrode determines settling time of signal during each measurement cycle. Given smaller transitions of the measured signal, less time is required to settle to a stable value before the next cycle. For example in Sequence 1 (Table 1) about 10 uSec (e.g., 4 time) constants are allowed for settling time. A smaller signal could settle to within an acceptable residual value in less time, say for example 3 or even 2 time constants.
- the measurement cycle may be shortened, resulting in faster measurements or the resistance of Rref can be increased, resulting in less attenuation of accumulated voltage during each measurement sequence.
- a second benefit is that it may not be necessary to discharge accumulator capacitors after each measurement sequence. Since voltage on each accumulator capacitor is measured and known at the end of each measurement sequence, this residual voltage may be subtracted from the voltage measured during the next measurement sequence and so on, providing that none of the accumulated signals exceeds circuit limits. This is particularly effective where two measurement sequences with opposite -phase signals are applied to each electrode, so a positive Vf from one Sequence will be at least partially reduced by a negative Vf of a subsequent Measurement Sequence.
- the voltage on accumulator capacitors generally trends toward the average Vref voltage.
- the period is related to the R-C time constant [Rref * (accumulator capacitor)] and the percentage of time that sampling switches (e.g., S4 in Fig. 3b) are closed.
- Drive circuit 92 and receive circuit 93 include D flip-flops A2 and A4 which can operate as threshold detectors. A2 is optional, and is only required if circuit 92 is to operate as a receive circuit in addition to driving pulses.
- Capacitors Cl and C2 isolate sensor 31 from circuits 92 and 93, so the voltage applied to electrodes Pl and P2 will have average values equal to Vrefl and Vref2.
- Vrefl and Vref2 may be held at Gnd potential, so 0.0 volts are applied to sensor 33. This can reduce negative effects of material migration and/or electrolysis that can occur in some systems in the presence of a non-zero time-averaged applied voltage.
- System 90 may be used to measure capacitance during either negative-going pulse transitions or positive-going pulse transitions. Preferably, measurements with positive- going transitions and negative-going transitions are alternated to reduce low frequency noise. This may be done in conjunction with any of the embodiments described herein.
- Receiver circuit 93 of system 90 has two switches rather than the single switch of circuit 33 in Fig. 3b.
- drive circuits connected to electrode Pl are very similar to the receive circuits connected to P2.
- sensor 31 parameters and circuit component values may be selected such that the drive circuit also function as a receive circuit, and the (Vref portion of the) receive circuit can function as a drive circuit.
- Fig. 10b shows system 100, an embodiment that is essentially identical to system
- Fig. 10c shows a circuit 110 that is similar to circuit 90 (Fig. 10a), except a stylus
- the tip of stylus 120 can be operated as the drive electrode while all sensor 31 electrodes (Pl and P2) operate as receive electrodes.
- the objective of circuit 110 is to measure the location of stylus 120 with respect to horizontal electrode(s) Pl and vertical electrode(s) P2.
- a voltage waveform at the tip of stylus 120 has positive and negative voltage transitions that couple signal currents 18 and 19 to electrodes Pl and P2 through capacitors CsI and Cs2 respectively.
- the stylus may be any signal-carrying conductive device. It may be a physical pointer device or it may be the finger of a user, provided the finger is activated with a signal that may be coupled to receiver electrodes, for example as described in US Patent No. 7,453,444.
- circuits 94 and 95 are both operated as receive circuits, so S3 and Sl both operate as described in Sequence 3, (or alternatively S4 and S2 can operate if positive stylus voltage transitions are to be measured).
- V90 and V91 are repeatedly connected to reference voltages Vl & V3, which are typically equal, so no significant voltage is applied to sensor 31 by circuit 94 or circuit 95.
- Currents 12 and 13 are preferably negligible, and the only significant current accumulated on capacitors C 1 and C2 are coupled from stylus 120.
- One horizontal electrode (Pl) and one vertical electrode (P2) are shown in Fig. 10c but in practice, multiple horizontal and multiple vertical electrodes are measured simultaneously or near simultaneously.
- Measurement Sequence 3 is repeated until at least one vertical electrode signal and one horizontal electrode signal accumulate enough voltage on accumulator capacitors to cross their respective thresholds, thus defining a contact point.
- stylus signal measurements are sufficiently large on several adjacent horizontal electrodes that interpolation can be used to calculate an accurate stylus position.
- Fig. 11 shows a schematic of simulated circuit 4 driving 16 receive electrodes simultaneously via 16 reference resistors. Circuit 4 is one implementation of system 90, and component designations in circuit 4 match those of corresponding components in system 90 (Fig.
- C2 1000pf.
- a total of 16 electrodes are driven in parallel, so Cm and Cr are simulated as lumped total capacitors of 16pf and 160pf respectively.
- a single driven electrode and its measurement circuit are shown, though more than one driven electrode is typically present. In fact, a major reason to swap drive and receive functions is to detect which of many driven electrodes are being touched.
- drive pulses are generated by Vref2 (rather than, for example, switches S3 and S4 of Fig. 10a).
- a single Vref2 drives 16 electrodes through 16 Rref s. These couple to (at least) one driven electrode.
- Switch S2 switches synchronously with (-) transitions of Vref2, so voltage (V91-V96) accumulates on C2 and V91 is measured at A2 using methods outlined in Sequence 1 (Table 1) and/or Sequence 2 (Table 2).
- the duration (lOuSec) and rate (50uSec) of drive pulses is slower because capacitance (for example, Cm) levels are higher and settling time of V96 and V91 are longer.
- One possible benefit of this embodiment is to detect touch to Driven electrodes by measuring the ratio of mutual capacitance(s) to capacitance-to-ground as described by Equation 1.
- Exclusive measurement of Cm would not be a goal of such an embodiment. Since all Receive electrodes (that is, 16 of them) are driven simultaneously, a 10% change in any single Cm due to a touch results in ⁇ 1% change in total Cm's. Thus, this embodiment is relatively insensitive to changes in Cm of any single electrode. But capacitance to ground of each driven electrode (that is, each of 16) is measured separately and simultaneously with sufficient sensitivity to detect a touch to any (or several) driven electrode. Sensitivity measurements from exemplary circuit 4 (Fig. 11) are shown in Table 3 (below).
- one method of scanning sensor 2 is to drive a signal onto electrode Da from circuit 21, and measure received signals simultaneously on all of electrodes Rcvl - Rcv4 with circuits 25 - 28. Then circuit 22 drives electrode Db, and Rcvl - Rcv4 are measured again (and so forth) until after four measurement sequences all Cm's are measured.
- circuits 25-28 drive pulses simultaneously onto electrodes Rcvl - Rcv4, and circuits 21 - 24 measure the pulses that are coupled to electrodes Da -
- Equation 1 indicates Cm coupled from driven electrodes should be less than Cd, in order to maximize the sensitivity to Cd.
- Touched electrode Cdb is then driven by circuit 22 and signals on Rcvl - Rcv4 are simultaneously measured by circuits 25 - 28.
- the touch at point Tl is resolved due to the change in mutual capacitance Cm2b, measured by circuit 26. (Methods relating to various embodiments disclosed herein may be used for this measurement).
- Touched electrode Cdc is then driven by circuit 23 and signals on Rcvl - Rcv4 are simultaneously measured by circuits 25 - 28.
- the touch at point T2 is resolved due to the change in capacitance Cm4c and the touch at T3 is resolved due to the change in capacitance Cm2c.
- Table 3 shows the sensitivity of five exemplary embodiments. Circuits were simulated as touch sensitive capacitors were changed by 10% as indicated, and the resulting change in voltage across Cl was measured after 40 to 100 measurement cycles.
- Embodiment 4 500 1 10 710 0 0
- Embodiment 5 1000 16 20 56 0 25
- Values of components and voltages and timing of waveforms circuits can be selected to match the parameters of touch sensors being measured.
- Cl, C2, Rref, Vref, V6, and others were chosen to operate with capacitances Cm, Cd, and Cr.
- component values and waveform timing may be adjusted to achieve accurate measurements.
- waveform timing can be adjusted and optimized under the control of a program in controller 29 (Fig. 2).
- receiver circuits 33 (Fig. 3b) and 93 (Fig. 10a, 10b, 10c) and driver circuits 94 (Fig. 10a, 10b, 10c) and Dl (Fig. 3b) may be implemented by configuring a programmed input/out (PIO) port of a typical microprocessor as an open collector switch, and using the PIO input gate/latch as a comparator.
- PIO programmed input/out
- Other common logic integrated circuits may also be used to implement these circuits.
- Other arrangements of standard low cost logic circuits will be apparent to those skilled in the art.
- ADC methods are used in the examples thus described. Additional methods will occur to those skilled in the art. Specifically, certain embodiments use timed ramps to measure the voltage on Cl . Alternatively, successive approximation and other faster ADC methods or a combination of ADC methods may be used if measurement time is important.
- circuits and methods described here can be used to implement high speed simultaneous measurements of multiple (receiver) electrodes, using standard circuit components at low cost.
- Circuits may also be configured from a simple microprocessor driving a few electrodes to a high resolution touch panel with many electrodes.
- Many of the embodiments described herein can be made from the standard PIO ports of microprocessors or low cost logic circuits, and a few passive external components. For example, a small mutual capacitance touch system with 8 buttons could be implemented with a simple microprocessor using one PIO port to drive one electrode and one PIO port to measure eight electrodes simultaneously.
- a microprocessor may be augmented with (low cost) circuits like the STP16CPS05 sixteen channel driver available from ST Microelectronics of Geneva, Switzerland, and/or the SN74LVC16646A 16-channel transceiver/register available from Texas Instruments of Dallas, Texas.
- measurement of signal is performed only during the sample time when the sampling switch (for example, S4 in system 30 (Fig. 3b)) is closed.
- the optimal signal measured in C 1 is a pulse of current with controlled rate of change and magnitude during the transition of voltage V6.
- S3 should be closed for the minimum time required to measure the current pulse that flows during transitions of V6.
- Noise harmonics with a period ⁇ [sample period], may be reduced by: 1. Varying the sample time in a pseudo-random fashion during each measurement cycle; or,
Abstract
Description
Claims
Priority Applications (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2011529115A JP2012503774A (en) | 2008-09-24 | 2009-09-16 | Circuit and method for measuring mutual capacitance |
EP09816711A EP2344895A4 (en) | 2008-09-24 | 2009-09-16 | Mutual capacitance measuring circuits and methods |
CN200980141593.0A CN102187236B (en) | 2008-09-24 | 2009-09-16 | Mutual capacitance measuring circuits and methods |
Applications Claiming Priority (6)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US9965008P | 2008-09-24 | 2008-09-24 | |
US61/099,650 | 2008-09-24 | ||
US15771509P | 2009-03-05 | 2009-03-05 | |
US61/157,715 | 2009-03-05 | ||
US18705009P | 2009-06-15 | 2009-06-15 | |
US61/187,050 | 2009-06-15 |
Publications (2)
Publication Number | Publication Date |
---|---|
WO2010036545A2 true WO2010036545A2 (en) | 2010-04-01 |
WO2010036545A3 WO2010036545A3 (en) | 2010-06-24 |
Family
ID=42037146
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/US2009/057114 WO2010036545A2 (en) | 2008-09-24 | 2009-09-16 | Mutual capacitance measuring circuits and methods |
Country Status (7)
Country | Link |
---|---|
US (1) | US8363031B2 (en) |
EP (1) | EP2344895A4 (en) |
JP (1) | JP2012503774A (en) |
KR (1) | KR20110067039A (en) |
CN (1) | CN102187236B (en) |
TW (1) | TW201018928A (en) |
WO (1) | WO2010036545A2 (en) |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2013538346A (en) * | 2010-08-12 | 2013-10-10 | フラウンホーファー−ゲゼルシャフト・ツール・フェルデルング・デル・アンゲヴァンテン・フォルシュング・アインゲトラーゲネル・フェライン | Capacitance measurement circuit, capacitance measurement sensor system, and capacitance measurement method for measuring capacitance using a sinusoidal voltage signal |
US10444862B2 (en) | 2014-08-22 | 2019-10-15 | Synaptics Incorporated | Low-profile capacitive pointing stick |
Families Citing this family (88)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
KR20110067039A (en) | 2008-09-24 | 2011-06-20 | 쓰리엠 이노베이티브 프로퍼티즈 컴파니 | Mutual capacitance measuring circuits and methods |
JP5067763B2 (en) * | 2008-10-08 | 2012-11-07 | 株式会社ジャパンディスプレイウェスト | Contact detection device, display device, and contact detection method |
US8866500B2 (en) | 2009-03-26 | 2014-10-21 | Cypress Semiconductor Corporation | Multi-functional capacitance sensing circuit with a current conveyor |
EP2435895A1 (en) * | 2009-05-29 | 2012-04-04 | 3M Innovative Properties Company | High speed multi-touch touch device and controller therefor |
TWI393041B (en) * | 2009-07-16 | 2013-04-11 | Elan Microelectronics Corp | Sensing Circuit and Method of Capacitive Touchpad |
CN102473059B (en) * | 2009-08-12 | 2015-06-24 | 瑟克公司 | Synchronous timed orthogonal measurement pattern for multi-touch sensing on touchpad |
US9753586B2 (en) * | 2009-10-08 | 2017-09-05 | 3M Innovative Properties Company | Multi-touch touch device with multiple drive frequencies and maximum likelihood estimation |
US9612691B2 (en) * | 2009-11-02 | 2017-04-04 | Au Optronics | Inducing capacitance detector and capacitive position detector of using same |
US8773366B2 (en) * | 2009-11-16 | 2014-07-08 | 3M Innovative Properties Company | Touch sensitive device using threshold voltage signal |
US8411066B2 (en) * | 2010-01-05 | 2013-04-02 | 3M Innovative Properties Company | High speed noise tolerant multi-touch touch device and controller therefor |
US9391607B2 (en) * | 2010-04-22 | 2016-07-12 | Qualcomm Technologies, Inc. | Use of random sampling technique to reduce finger-coupled noise |
US8493356B2 (en) | 2010-04-22 | 2013-07-23 | Maxim Integrated Products, Inc. | Noise cancellation technique for capacitive touchscreen controller using differential sensing |
WO2011149750A2 (en) * | 2010-05-25 | 2011-12-01 | 3M Innovative Properties Company | High speed low power multi-touch touch device and controller therefor |
US20120026131A1 (en) * | 2010-07-28 | 2012-02-02 | Bytheway Jared G | Reducing noise susceptibility in a mutual capacitance touchpad through axis swapping |
US9823785B2 (en) | 2010-09-09 | 2017-11-21 | 3M Innovative Properties Company | Touch sensitive device with stylus support |
US10019119B2 (en) * | 2010-09-09 | 2018-07-10 | 3M Innovative Properties Company | Touch sensitive device with stylus support |
US9389724B2 (en) * | 2010-09-09 | 2016-07-12 | 3M Innovative Properties Company | Touch sensitive device with stylus support |
US9454268B2 (en) | 2010-10-12 | 2016-09-27 | Parade Technologies, Ltd. | Force sensing capacitive hybrid touch sensor |
US9459736B2 (en) * | 2010-10-12 | 2016-10-04 | Parade Technologies, Ltd. | Flexible capacitive sensor array |
DE102010049962B4 (en) * | 2010-10-28 | 2014-01-02 | Austriamicrosystems Ag | Sensor arrangement and method for operating a sensor arrangement |
TWI441065B (en) * | 2010-11-03 | 2014-06-11 | Elan Microelectronics Corp | A Capacitive Touch Element for Identifying Conductor and Non - Conductor and Its Method of Discrimination |
US9310923B2 (en) | 2010-12-03 | 2016-04-12 | Apple Inc. | Input device for touch sensitive devices |
US8933906B2 (en) | 2011-02-02 | 2015-01-13 | 3M Innovative Properties Company | Patterned substrates with non-linear conductor traces |
US9736928B2 (en) | 2011-02-02 | 2017-08-15 | 3M Innovative Properties Company | Patterned substrates with darkened conductor traces |
US9268441B2 (en) | 2011-04-05 | 2016-02-23 | Parade Technologies, Ltd. | Active integrator for a capacitive sense array |
US9323385B2 (en) * | 2011-04-05 | 2016-04-26 | Parade Technologies, Ltd. | Noise detection for a capacitance sensing panel |
US20120280923A1 (en) * | 2011-04-08 | 2012-11-08 | Paul Vincent | System for protecting pin data when using touch capacitive touch technology on a point-of-sale terminal or an encrypting pin pad device |
US8884891B2 (en) * | 2011-04-29 | 2014-11-11 | Broadcom Corporation | Transmit/receive switch for a touch-screen system |
US8736574B2 (en) * | 2011-05-19 | 2014-05-27 | Microsoft Corporation | Pressure-sensitive multi-touch device |
US8928635B2 (en) | 2011-06-22 | 2015-01-06 | Apple Inc. | Active stylus |
US9329703B2 (en) | 2011-06-22 | 2016-05-03 | Apple Inc. | Intelligent stylus |
US8638320B2 (en) * | 2011-06-22 | 2014-01-28 | Apple Inc. | Stylus orientation detection |
US9829520B2 (en) * | 2011-08-22 | 2017-11-28 | Keithley Instruments, Llc | Low frequency impedance measurement with source measure units |
KR101338285B1 (en) * | 2012-01-12 | 2013-12-09 | 주식회사 하이딥 | Method, processing device and computer-readable recording medium for sensing touch on touch panel |
US9244570B2 (en) * | 2012-01-17 | 2016-01-26 | Atmel Corporation | System and method for reducing the effects of parasitic capacitances |
US20130207926A1 (en) | 2012-02-15 | 2013-08-15 | Viktor Kremin | Stylus to host synchronization |
KR101343821B1 (en) * | 2012-03-06 | 2013-12-20 | 주식회사 리딩유아이 | Capacitance measuring circuit of a touch sensor and capacitance type touch panel |
KR102004329B1 (en) * | 2012-05-11 | 2019-07-26 | 삼성전자주식회사 | Coordinate indicating apparatus and coordinate measuring apparaturs which measures input position of coordinate indicating apparatus |
CN102760019A (en) * | 2012-06-28 | 2012-10-31 | 华映视讯(吴江)有限公司 | Electrode array of touch panel |
US8780065B2 (en) * | 2012-07-19 | 2014-07-15 | Cypress Semiconductor Corporation | Interface and synchronization method between touch controller and display driver for operation with touch integrated displays |
US9557845B2 (en) | 2012-07-27 | 2017-01-31 | Apple Inc. | Input device for and method of communication with capacitive devices through frequency variation |
US9176604B2 (en) | 2012-07-27 | 2015-11-03 | Apple Inc. | Stylus device |
US9652090B2 (en) | 2012-07-27 | 2017-05-16 | Apple Inc. | Device for digital communication through capacitive coupling |
JP5984259B2 (en) * | 2012-09-20 | 2016-09-06 | 株式会社ワコム | Position detection device |
US9395171B2 (en) * | 2012-11-05 | 2016-07-19 | Siemens Energy, Inc. | Capacitive sensor with orthogonal fields |
CN103134996B (en) * | 2013-01-31 | 2015-12-09 | 珠海中慧微电子有限公司 | Adopt mutual capacitance sensing circuit and the method for charge compensation |
US8779783B1 (en) | 2013-03-12 | 2014-07-15 | Cypress Semiconductor Corporation | Mutual capacitance sensing using a self-capacitance sensing device |
US8890841B2 (en) | 2013-03-13 | 2014-11-18 | 3M Innovative Properties Company | Capacitive-based touch apparatus and method therefor, with reduced interference |
US10048775B2 (en) | 2013-03-14 | 2018-08-14 | Apple Inc. | Stylus detection and demodulation |
TWI549025B (en) * | 2013-05-08 | 2016-09-11 | 廣達電腦股份有限公司 | Touch panel |
JP2015005182A (en) * | 2013-06-21 | 2015-01-08 | カシオ計算機株式会社 | Input device, input method, program and electronic apparatus |
KR101514522B1 (en) * | 2013-06-28 | 2015-05-04 | 삼성전기주식회사 | Touch sensing apparatus and touchscreen apparatus |
US10845901B2 (en) | 2013-07-31 | 2020-11-24 | Apple Inc. | Touch controller architecture |
ITTO20130657A1 (en) * | 2013-08-01 | 2015-02-02 | St Microelectronics Srl | PROCEDURE, EQUIPMENT AND DEVICE FOR RECOGNITION OF GESTURES, RELATIVE COMPUTER PRODUCT |
ITTO20130659A1 (en) * | 2013-08-01 | 2015-02-02 | St Microelectronics Srl | PROCEDURE, EQUIPMENT AND DEVICE FOR RECOGNITION OF GESTURES, RELATIVE COMPUTER PRODUCT |
US9164136B2 (en) * | 2013-12-02 | 2015-10-20 | Atmel Corporation | Capacitive measurement circuit for a touch sensor device |
KR20160105465A (en) | 2014-01-03 | 2016-09-06 | 쓰리엠 이노베이티브 프로퍼티즈 컴파니 | Capacitive touch systems and methods using differential signal techniques |
WO2015138984A1 (en) | 2014-03-14 | 2015-09-17 | The Regents Of The University Of California | Bootstrapped and correlated double sampling (bcds) non-contact touch sensor for mobile devices |
JP6358497B2 (en) * | 2014-04-19 | 2018-07-18 | Tianma Japan株式会社 | Control device |
US9417729B2 (en) * | 2014-06-09 | 2016-08-16 | Atmel Corporation | Charge compensation during touch sensing |
US20170177114A1 (en) * | 2014-08-07 | 2017-06-22 | 3M Innovative Properties Company | Force-sensing capacitor elements, deformable membranes and electronic devices fabricated therefrom |
JP6406697B2 (en) * | 2014-09-17 | 2018-10-17 | 株式会社ワコム | Position detection apparatus and position detection method |
KR101648632B1 (en) * | 2014-09-18 | 2016-08-16 | 장욱 | Multi-touch apparatus and operating method thereof |
US9542051B2 (en) * | 2014-10-24 | 2017-01-10 | Microchip Technology Incorporated | Analog elimination of ungrounded conductive objects in capacitive sensing |
WO2016068016A1 (en) * | 2014-10-28 | 2016-05-06 | シャープ株式会社 | Touch panel evaluation data acquisition device |
WO2016073153A1 (en) | 2014-11-05 | 2016-05-12 | 3M Innovative Properties Company | Force-sensing capacitor elements, deformable membranes and electronic devices fabricated therefrom |
US10061450B2 (en) | 2014-12-04 | 2018-08-28 | Apple Inc. | Coarse scan and targeted active mode scan for touch |
EP3241098B1 (en) * | 2015-01-04 | 2023-02-22 | Microsoft Technology Licensing, LLC | Active stylus communication with a digitizer |
DE112015005942T5 (en) | 2015-01-13 | 2017-10-19 | Sumitomo Riko Company Limited | Capacitance measuring device, capacitance-type flat sensor device and capacitance-type liquid level detection device |
CN106153708A (en) * | 2015-04-17 | 2016-11-23 | 北京中科纳通电子技术有限公司 | A kind of experimental technique of test touch screen silver slurry anti-silver transfer ability |
CN106325632B (en) * | 2015-06-15 | 2020-12-15 | 恩智浦美国有限公司 | Capacitive sensor with noise suppression |
JP6613657B2 (en) * | 2015-06-29 | 2019-12-04 | ぺんてる株式会社 | Capacitive coupling type electrostatic sensor |
WO2017085997A1 (en) * | 2015-11-19 | 2017-05-26 | シャープ株式会社 | Touch position detection method, touch panel controller, and electronic device |
US9983748B2 (en) * | 2016-02-17 | 2018-05-29 | Atmel Corporation | Connecting electrodes to voltages |
US10474277B2 (en) | 2016-05-31 | 2019-11-12 | Apple Inc. | Position-based stylus communication |
JP6715696B2 (en) * | 2016-06-22 | 2020-07-01 | 株式会社ワコム | Electronic pen |
TWI584254B (en) * | 2016-08-05 | 2017-05-21 | Chipone Technology (Beijing)Co Ltd | Drive signal generation circuit |
US10162467B2 (en) * | 2017-03-08 | 2018-12-25 | Cypress Semiconductor Corporation | Ratiometric mutual-capacitance-to-code converter |
DE102018107478A1 (en) * | 2017-09-14 | 2019-03-14 | Huf Hülsbeck & Fürst Gmbh & Co. Kg | Method and evaluation system for evaluating a capacitive sensor in a vehicle |
US10656191B2 (en) * | 2017-12-18 | 2020-05-19 | Microsoft Technology Licensing, Llc | Capacitance measuring circuit |
US10521045B2 (en) * | 2018-02-14 | 2019-12-31 | Microchip Technology Incorporated | Reference noise rejection improvement based on sample and hold circuitry |
WO2019215687A1 (en) * | 2018-05-11 | 2019-11-14 | Vicwood Prosperity Technology Limited | Living body detection method and apparatus (touching behavior) |
GB2584669B (en) * | 2019-06-10 | 2022-03-30 | Touchnetix Ltd | Touch-sensitive apparatus and method |
KR20210124649A (en) * | 2020-04-07 | 2021-10-15 | 주식회사 하이딥 | Touch apparatus and touch detection method thereof |
CN112803939A (en) * | 2021-01-07 | 2021-05-14 | 海速芯(无锡)科技有限公司 | High-speed multi-channel parallel detection device for tiny capacitors |
CN113655290A (en) * | 2021-08-19 | 2021-11-16 | 北京他山科技有限公司 | Analog signal router |
CN113777409A (en) * | 2021-08-19 | 2021-12-10 | 北京他山科技有限公司 | Distributed capacitive sensor system |
US11914831B1 (en) * | 2023-02-05 | 2024-02-27 | Shenzhen GOODIX Technology Co., Ltd. | Self-capacitor sensing for capacitive touch panels |
Family Cites Families (94)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3732369A (en) | 1971-04-05 | 1973-05-08 | Welland Investment Trust | Coordinate digitizer system |
US4071691A (en) | 1976-08-24 | 1978-01-31 | Peptek, Inc. | Human-machine interface apparatus |
US4175239A (en) | 1978-04-12 | 1979-11-20 | P. R. Mallory & Co. Inc. | Detection means for touch control switches |
US4686332A (en) | 1986-06-26 | 1987-08-11 | International Business Machines Corporation | Combined finger touch and stylus detection system for use on the viewing surface of a visual display device |
JPS56114028A (en) | 1980-02-12 | 1981-09-08 | Kureha Chem Ind Co Ltd | Capacity-type coordinate input device |
US4323829A (en) | 1980-07-28 | 1982-04-06 | Barry M. Fish | Capacitive sensor control system |
US4639720A (en) | 1981-01-12 | 1987-01-27 | Harris Corporation | Electronic sketch pad |
US4581483A (en) | 1984-03-30 | 1986-04-08 | Koala Technologies Corporation | Interface circuitry for interconnecting touch tablet with a computer interface |
CA1306539C (en) | 1984-10-08 | 1992-08-18 | Takahide Ohtani | Signal reproduction apparatus including touched state pattern recognitionspeed control |
GB8808614D0 (en) | 1988-04-12 | 1988-05-11 | Renishaw Plc | Displacement-responsive devices with capacitive transducers |
JP2733300B2 (en) | 1989-04-28 | 1998-03-30 | 松下電器産業株式会社 | Key input device |
US5305017A (en) | 1989-08-16 | 1994-04-19 | Gerpheide George E | Methods and apparatus for data input |
US5189417A (en) | 1990-10-16 | 1993-02-23 | Donnelly Corporation | Detection circuit for matrix touch pad |
US5861583A (en) | 1992-06-08 | 1999-01-19 | Synaptics, Incorporated | Object position detector |
US5488204A (en) | 1992-06-08 | 1996-01-30 | Synaptics, Incorporated | Paintbrush stylus for capacitive touch sensor pad |
DE69324067T2 (en) | 1992-06-08 | 1999-07-15 | Synaptics Inc | Object position detector |
US5880411A (en) | 1992-06-08 | 1999-03-09 | Synaptics, Incorporated | Object position detector with edge motion feature and gesture recognition |
US6239389B1 (en) | 1992-06-08 | 2001-05-29 | Synaptics, Inc. | Object position detection system and method |
US5914465A (en) * | 1992-06-08 | 1999-06-22 | Synaptics, Inc. | Object position detector |
US5349353A (en) | 1992-12-28 | 1994-09-20 | Zrilic Djuro G | Method and apparatus for mixed analog and digital processing of delta modulated pulse streams including digital-to-analog conversion of a digital input signal |
US5572205A (en) | 1993-03-29 | 1996-11-05 | Donnelly Technology, Inc. | Touch control system |
TW274598B (en) | 1994-11-15 | 1996-04-21 | Alps Electric Co Ltd | Coordinate input device for pen of finger tip |
US5790107A (en) | 1995-06-07 | 1998-08-04 | Logitech, Inc. | Touch sensing method and apparatus |
US5730165A (en) | 1995-12-26 | 1998-03-24 | Philipp; Harald | Time domain capacitive field detector |
US5825352A (en) | 1996-01-04 | 1998-10-20 | Logitech, Inc. | Multiple fingers contact sensing method for emulating mouse buttons and mouse operations on a touch sensor pad |
US5920309A (en) | 1996-01-04 | 1999-07-06 | Logitech, Inc. | Touch sensing method and apparatus |
TW408277B (en) | 1996-11-15 | 2000-10-11 | Alps Electric Co Ltd | Small current detector circuit and locator device using the same |
JP3394187B2 (en) | 1997-08-08 | 2003-04-07 | シャープ株式会社 | Coordinate input device and display integrated type coordinate input device |
EP2256605B1 (en) | 1998-01-26 | 2017-12-06 | Apple Inc. | Method and apparatus for integrating manual input |
US7663607B2 (en) | 2004-05-06 | 2010-02-16 | Apple Inc. | Multipoint touchscreen |
FR2774497B1 (en) | 1998-02-05 | 2000-07-21 | Daniel Ansel | METHOD USING SIGNAL ANALYSIS FOR CONTROLLING REMOTE ELECTRICAL DEVICES AND ASSOCIATED DEVICES |
JP2000076014A (en) | 1998-08-27 | 2000-03-14 | Pentel Kk | Electrostatic capacitance type touch panel device |
US6466036B1 (en) * | 1998-11-25 | 2002-10-15 | Harald Philipp | Charge transfer capacitance measurement circuit |
US7019672B2 (en) | 1998-12-24 | 2006-03-28 | Synaptics (Uk) Limited | Position sensor |
US7218498B2 (en) | 1999-01-19 | 2007-05-15 | Touchsensor Technologies Llc | Touch switch with integral control circuit |
US6535200B2 (en) | 1999-01-25 | 2003-03-18 | Harald Philipp | Capacitive position sensor |
JP4275865B2 (en) * | 1999-01-26 | 2009-06-10 | キューアールジー リミテッド | Capacitive sensors and arrays |
KR100366503B1 (en) | 2000-06-13 | 2003-01-09 | 주식회사 엘지이아이 | Glass touch detecting circuit |
US6879930B2 (en) | 2001-03-30 | 2005-04-12 | Microsoft Corporation | Capacitance touch slider |
US20030067447A1 (en) | 2001-07-09 | 2003-04-10 | Geaghan Bernard O. | Touch screen with selective touch sources |
US7046230B2 (en) | 2001-10-22 | 2006-05-16 | Apple Computer, Inc. | Touch pad handheld device |
US7265746B2 (en) | 2003-06-04 | 2007-09-04 | Illinois Tool Works Inc. | Acoustic wave touch detection circuit and method |
KR100453971B1 (en) | 2002-03-25 | 2004-10-20 | 전자부품연구원 | Integral capacity-voltage converter |
AU2003219506B2 (en) | 2002-04-15 | 2009-02-05 | Qualcomm Incorporated | Method and system for obtaining positioning data |
US7129714B2 (en) | 2002-07-02 | 2006-10-31 | Baxter Larry K | Capacitive measurement system |
US20040004488A1 (en) | 2002-07-02 | 2004-01-08 | Baxter Larry K. | Capacitive sensor circuit with good noise rejection |
US6933931B2 (en) | 2002-08-23 | 2005-08-23 | Ceronix, Inc. | Method and apparatus of position location |
CN100440309C (en) | 2002-08-29 | 2008-12-03 | N-特莱格有限公司 | Transparent digitiser |
US20060012944A1 (en) | 2002-10-31 | 2006-01-19 | Mamigonians Hrand M | Mechanically operable electrical device |
CN1708672B (en) * | 2002-10-31 | 2010-05-12 | 量研科技股份有限公司 | Charge transfer capacitive position sensor |
US6970160B2 (en) | 2002-12-19 | 2005-11-29 | 3M Innovative Properties Company | Lattice touch-sensing system |
TWM240050U (en) | 2003-04-02 | 2004-08-01 | Elan Microelectronics Corp | Capacitor touch panel with integrated keyboard and handwriting function |
GB0323570D0 (en) * | 2003-10-08 | 2003-11-12 | Harald Philipp | Touch-sensitivity control panel |
US7649524B2 (en) | 2004-07-15 | 2010-01-19 | N-Trig Ltd. | Tracking window for a digitizer system |
US20060227114A1 (en) | 2005-03-30 | 2006-10-12 | Geaghan Bernard O | Touch location determination with error correction for sensor movement |
CN100370402C (en) | 2005-08-05 | 2008-02-20 | 鸿富锦精密工业(深圳)有限公司 | Touch type inductor |
EP1922602A2 (en) | 2005-08-11 | 2008-05-21 | N-trig Ltd. | Apparatus for object information detection and methods of using same |
JP4073449B2 (en) | 2005-08-18 | 2008-04-09 | 義隆電子股▲ふん▼有限公司 | Touch gesture detection method |
US20070074913A1 (en) | 2005-10-05 | 2007-04-05 | Geaghan Bernard O | Capacitive touch sensor with independently adjustable sense channels |
TWI304471B (en) | 2005-10-14 | 2008-12-21 | Hon Hai Prec Ind Co Ltd | The touch sensing apparatus |
CN1832349A (en) | 2006-04-19 | 2006-09-13 | 北京希格玛晶华微电子有限公司 | Capacitor measuring touch sensing identifying method and implementing device |
US8279180B2 (en) | 2006-05-02 | 2012-10-02 | Apple Inc. | Multipoint touch surface controller |
US20070268272A1 (en) | 2006-05-19 | 2007-11-22 | N-Trig Ltd. | Variable capacitor array |
KR101251999B1 (en) * | 2006-06-13 | 2013-04-08 | 삼성디스플레이 주식회사 | Liquid crystal display device, and driving method thereof |
JP4602941B2 (en) | 2006-06-15 | 2010-12-22 | 株式会社東海理化電機製作所 | Capacitance sensor circuit |
US10796390B2 (en) | 2006-07-03 | 2020-10-06 | 3M Innovative Properties Company | System and method for medical coding of vascular interventional radiology procedures |
US9360967B2 (en) | 2006-07-06 | 2016-06-07 | Apple Inc. | Mutual capacitance touch sensing device |
US8902173B2 (en) * | 2006-09-29 | 2014-12-02 | Cypress Semiconductor Corporation | Pointing device using capacitance sensor |
KR20080032901A (en) | 2006-10-11 | 2008-04-16 | 삼성전자주식회사 | Apparatus and method for multi-touch decision |
US9201556B2 (en) | 2006-11-08 | 2015-12-01 | 3M Innovative Properties Company | Touch location sensing system and method employing sensor data fitting to a predefined curve |
US8207944B2 (en) * | 2006-12-19 | 2012-06-26 | 3M Innovative Properties Company | Capacitance measuring circuit and method |
US8094128B2 (en) | 2007-01-03 | 2012-01-10 | Apple Inc. | Channel scan logic |
US8711129B2 (en) | 2007-01-03 | 2014-04-29 | Apple Inc. | Minimizing mismatch during compensation |
US7812827B2 (en) | 2007-01-03 | 2010-10-12 | Apple Inc. | Simultaneous sensing arrangement |
US8125456B2 (en) | 2007-01-03 | 2012-02-28 | Apple Inc. | Multi-touch auto scanning |
US7643011B2 (en) | 2007-01-03 | 2010-01-05 | Apple Inc. | Noise detection in multi-touch sensors |
US8054299B2 (en) | 2007-01-08 | 2011-11-08 | Apple Inc. | Digital controller for a true multi-point touch surface useable in a computer system |
TWI340911B (en) | 2007-04-13 | 2011-04-21 | Generalplus Technology Inc | Capacitance touch sensor |
US8493331B2 (en) | 2007-06-13 | 2013-07-23 | Apple Inc. | Touch detection using multiple simultaneous frequencies |
US20090009483A1 (en) | 2007-06-13 | 2009-01-08 | Apple Inc. | Single-chip touch controller with integrated drive system |
WO2009013746A1 (en) | 2007-07-26 | 2009-01-29 | N-Trig Ltd. | System and method for diagnostics of a grid based digitizer |
JP4957511B2 (en) | 2007-10-31 | 2012-06-20 | ソニー株式会社 | Display device and electronic device |
JP2009122969A (en) | 2007-11-15 | 2009-06-04 | Hitachi Displays Ltd | Screen input-type image-displaying device |
US7830157B2 (en) | 2007-12-28 | 2010-11-09 | 3M Innovative Properties Company | Pulsed capacitance measuring circuits and methods |
US20090194344A1 (en) | 2008-01-31 | 2009-08-06 | Avago Technologies Ecbu Ip (Singapore) Pte. Ltd. | Single Layer Mutual Capacitance Sensing Systems, Device, Components and Methods |
JP5098042B2 (en) | 2008-02-13 | 2012-12-12 | 株式会社ワコム | Position detection apparatus and position detection method |
US8284332B2 (en) | 2008-08-01 | 2012-10-09 | 3M Innovative Properties Company | Touch screen sensor with low visibility conductors |
WO2009140347A2 (en) | 2008-05-14 | 2009-11-19 | 3M Innovative Properties Company | Systems and methods for assessing locations of multiple touch inputs |
KR20110067039A (en) | 2008-09-24 | 2011-06-20 | 쓰리엠 이노베이티브 프로퍼티즈 컴파니 | Mutual capacitance measuring circuits and methods |
US8711121B2 (en) | 2008-12-12 | 2014-04-29 | Wacom Co., Ltd. | Architecture and method for multi-aspect touchscreen scanning |
US9342202B2 (en) | 2009-01-23 | 2016-05-17 | Qualcomm Incorporated | Conductive multi-touch touch panel |
EP2435895A1 (en) | 2009-05-29 | 2012-04-04 | 3M Innovative Properties Company | High speed multi-touch touch device and controller therefor |
US9323398B2 (en) | 2009-07-10 | 2016-04-26 | Apple Inc. | Touch and hover sensing |
WO2011087817A1 (en) | 2009-12-21 | 2011-07-21 | Tactus Technology | User interface system |
-
2009
- 2009-09-16 KR KR1020117008489A patent/KR20110067039A/en not_active Application Discontinuation
- 2009-09-16 WO PCT/US2009/057114 patent/WO2010036545A2/en active Application Filing
- 2009-09-16 EP EP09816711A patent/EP2344895A4/en not_active Withdrawn
- 2009-09-16 CN CN200980141593.0A patent/CN102187236B/en not_active Expired - Fee Related
- 2009-09-16 US US12/560,545 patent/US8363031B2/en not_active Expired - Fee Related
- 2009-09-16 JP JP2011529115A patent/JP2012503774A/en active Pending
- 2009-09-23 TW TW098132112A patent/TW201018928A/en unknown
Non-Patent Citations (1)
Title |
---|
See references of EP2344895A4 * |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2013538346A (en) * | 2010-08-12 | 2013-10-10 | フラウンホーファー−ゲゼルシャフト・ツール・フェルデルング・デル・アンゲヴァンテン・フォルシュング・アインゲトラーゲネル・フェライン | Capacitance measurement circuit, capacitance measurement sensor system, and capacitance measurement method for measuring capacitance using a sinusoidal voltage signal |
US9612266B2 (en) | 2010-08-12 | 2017-04-04 | Fraunhofer-Gesellschaft Zur Foerderung Der Angewandten Forschung E.V. | Capacity measuring circuit, sensor system and method for measuring a capacity using a sinusoidal voltage signal |
US10444862B2 (en) | 2014-08-22 | 2019-10-15 | Synaptics Incorporated | Low-profile capacitive pointing stick |
Also Published As
Publication number | Publication date |
---|---|
CN102187236A (en) | 2011-09-14 |
US8363031B2 (en) | 2013-01-29 |
US20100073323A1 (en) | 2010-03-25 |
CN102187236B (en) | 2015-04-22 |
KR20110067039A (en) | 2011-06-20 |
WO2010036545A3 (en) | 2010-06-24 |
JP2012503774A (en) | 2012-02-09 |
EP2344895A2 (en) | 2011-07-20 |
EP2344895A4 (en) | 2013-02-27 |
TW201018928A (en) | 2010-05-16 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US8363031B2 (en) | Mutual capacitance measuring circuits and methods | |
US8248383B2 (en) | Multi-touch touch screen with single-layer ITO bars arranged in parallel | |
US8248084B2 (en) | Touch detection techniques for capacitive touch sense systems | |
US7977954B2 (en) | Methods and systems for sigma delta capacitance measuring using shared components | |
US7521941B2 (en) | Methods and systems for detecting a capacitance using switched charge transfer techniques | |
US7830157B2 (en) | Pulsed capacitance measuring circuits and methods | |
US7982471B2 (en) | Capacitance measurement system and method | |
US7902842B2 (en) | Methods and systems for switched charge transfer capacitance measuring using shared components | |
US8493358B2 (en) | High speed low power multi-touch touch device and controller therefor | |
US7449895B2 (en) | Methods and systems for detecting a capacitance using switched charge transfer techniques | |
US8575947B1 (en) | Receive demodulator for capacitive sensing | |
US8174273B2 (en) | Capacitance measurement circuit with dynamic feedback | |
US8018238B2 (en) | Embedded sar based active gain capacitance measurement system and method | |
US7924029B2 (en) | Half-bridge for capacitive sensing | |
KR20080012936A (en) | Methods and systems for detecting a capacitance using switched charge transfer techniques | |
JP4727754B1 (en) | Capacitive touch panel | |
KR101507137B1 (en) | System and Method for Recogniging of Touch Signals | |
Geaghan et al. | 32.4: Low Cost Mutual Capacitance Measuring Circuits and Methods |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
WWE | Wipo information: entry into national phase |
Ref document number: 200980141593.0 Country of ref document: CN |
|
121 | Ep: the epo has been informed by wipo that ep was designated in this application |
Ref document number: 09816711 Country of ref document: EP Kind code of ref document: A2 |
|
WWE | Wipo information: entry into national phase |
Ref document number: 1731/CHENP/2011 Country of ref document: IN |
|
WWE | Wipo information: entry into national phase |
Ref document number: 2011529115 Country of ref document: JP |
|
NENP | Non-entry into the national phase |
Ref country code: DE |
|
ENP | Entry into the national phase |
Ref document number: 20117008489 Country of ref document: KR Kind code of ref document: A |
|
WWE | Wipo information: entry into national phase |
Ref document number: 2009816711 Country of ref document: EP |