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WO2002003368A1 - Procede et dispositif destines a ameliorer l'immunite au bruit des ecrans tactiles - Google Patents

Procede et dispositif destines a ameliorer l'immunite au bruit des ecrans tactiles Download PDF

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Publication number
WO2002003368A1
WO2002003368A1 PCT/US2001/020935 US0120935W WO0203368A1 WO 2002003368 A1 WO2002003368 A1 WO 2002003368A1 US 0120935 W US0120935 W US 0120935W WO 0203368 A1 WO0203368 A1 WO 0203368A1
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WO
WIPO (PCT)
Prior art keywords
voltage
test line
readings
stylus
rate
Prior art date
Application number
PCT/US2001/020935
Other languages
English (en)
Inventor
Carlos Ribas
Luis Dib
Original Assignee
Bsquare Corporation
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Bsquare Corporation filed Critical Bsquare Corporation
Priority to AU2001270274A priority Critical patent/AU2001270274A1/en
Publication of WO2002003368A1 publication Critical patent/WO2002003368A1/fr

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Classifications

    • G—PHYSICS
    • G06—COMPUTING OR CALCULATING; 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
    • G06F3/045—Digitisers, e.g. for touch screens or touch pads, characterised by the transducing means using resistive elements, e.g. a single continuous surface or two parallel surfaces put in contact

Definitions

  • This invention relates to improving noise immunity in electrical circuits.
  • the invention is more particularly related to the improving noise immunity in touch screen applications.
  • the invention is also more particularly related to the measurement of stylus position and determination of stylus up/down (PU/PD) simultaneously to reduce false position readings.
  • the invention includes the application of known or calculatable voltages to gates of electronic devices to reduce float, and the determination of a max rate of change against which measurements are compared to determine validity.
  • Touch screens are utilized in many modem devices, including computer displays, cash registers, medical equipment, Personal Data Assistants (PDAD s), and other devices.
  • a typical touch screen consists of a 4- wire resistor network constructed from two resistive planes positioned closely together (see Fig. 1, for example).
  • the touch screen can be modeled as two resistors, one resistor for an X plane R x total ( l + R2), and one resistor for a Y plane R y total (R3 + R4).
  • Fig. 2 illustrates a configuration of the touch screen X and Y planes and a stylus (pen) 200.
  • a resistance between the X and Y planes is essentially infinite (high impedance, very large value).
  • a connection resistance R5 is formed that connects X and Y planes.
  • contact by the pen 200 also divides each of the R x tota ⁇ and R y tota i plane resistors into component resistances (Rl and R2 for the X plane, and R3 and R4 for the Y plane).
  • Fig. 3 illustrates an example arrangement for polarizing the X plane with a known bias voltage to determine an X position measurement of the stylus.
  • the voltage (V 3 oo) at the juncture of Rl and R2, 300, corresponds to the point where the stylus makes contact with the touch screen.
  • a comparison of the bias voltage to voltage at 300 (V 300 /V BI A S ) provides a ratio that indicates a position of the stylus in an X direction.
  • connection resistances are part of an electrical path attached to the juncture point 300, and allow the voltage at the high impedance amplifier 310 input to raise to the level of juncture 300.
  • the amplifier output is then measured and the X axis distance is calculated, hi this case the 2N measured a juncture 300 indicate that the stylus is 2/5 ths (2N/5N) of a distance across the X plane.
  • a second, but similar process is then applied to the Y axis, applying a V BIAS and measuring voltage at juncture point 320. Again, the measured voltage is used to determine a position of the stylus, in this case, a distance across the Y plane. Combined, the X and Y distances provide a position of the stylus or pen.
  • a third process is applied to determine whether the stylus is up (Pen Up PU) or down (Pen Down PD), referred to as touch detection.
  • touch detection is typically performed by applying a known voltage (usually V DD ) i series with an internal resistance R ⁇ T connected to the touch screen. Voltage changes at extreme ends of the touch screen are detected, the voltage changes due to contact between the X and Y planes through R5.
  • Schmidt trigger voltage detectors 410/420 (alternatively, any type of circuit that performs an A/D conversion may be utilized, a hysteresis type device is preferred), the voltage levels are converted to digital logic values 1 and 0 which can be stored in a table or otherwise utilized to trigger an interrupt in a processing unit that detects a change in status from D Stylus is UpD (PU) to D Stylus is downD (PD).
  • PU UpD
  • PD D Stylus is downD
  • an AND device 430 detects different voltage levels on opposite sides of the X plane, indicating a PD (pen down) condition (touch detection). Conversely, closely matching voltages indicate a PU condition.
  • FIG. 5 illustrates an example of timing of the various processes for X position 500, Y position 510, and PU/PD 520.
  • problems exist, particularly in the area of spikes and inaccurate readings of touch screens that cause false or mcorrect position detections of the stylus or pen.
  • the present inventors have realized that noise and spike conditions occur on touch screens for a number of reasons. For example, imperfections on a touch screen surface cause stylus pressure to vary widely, if only momentarily. Furthermore, measurements for position and touch detection are performed at different times, and voltages present at an amplifier detecting position voltages do not necessarily correspond to stylus up or down conditions that are detected during a different time period. Still further, float voltages at a measurement amplifier during times of non contact between a stylus and touch screen may cause widely varying readings.
  • the present invention provides for stable noise immune readings on a touch screen by reading each of X or Y positions of a stylus in conjunction with a PU/PD reading (see Fig. 5 A).
  • the invention includes the provision of a control mechanism to maintain a known or calculatable voltage (a predetermined drift rate) at inputs to measurement devices (Schmidt triggers, A/D's, etc.) during periods of non-contact between a stylus and the touch screen.
  • a control mechanism to maintain a known or calculatable voltage (a predetermined drift rate) at inputs to measurement devices (Schmidt triggers, A/D's, etc.) during periods of non-contact between a stylus and the touch screen.
  • the control mechanism makes the voltage drift at the predetermined rate, fri one embodiment, as shown in Fig.
  • the invention also includes a method for detecting erroneous readings by comparing changes in consecutive readings against a maximum rate of change for valid readings.
  • the invention may be embodied as a circuit for testing a voltage on a test line subject to float conditions, comprising, a detection device having an input coupled to said test line, said detection device configured to detect voltages on said test line, a charging device configured to place an amount of charge on said test line at a rate of change greater than a max rate of change for non floating voltages carried on said test line; and a selection device configured to eliminate detections by said detection device that are mainly attributable to said charging device.
  • the invention may also be embodied as a method of noise immunity improvement a line being tested (test line), comprising the steps of, reading a first amount of voltage (RVl) present on said test line during a first reading time point, reading a second amount of voltage (RV2) present on said test line during a second reading time point, calculating a difference in voltage between the RN1 and RN2 voltage readings, invalidating the voltage readings if the difference in RN1 and RV2 is greater than a maximum rate of change of valid voltages on said test line, and determining a valid reading based on RVl and RV2 if the difference in RVl and RV2 is less than the maximum rate of change of valid voltages on said test line.
  • RVl first amount of voltage
  • RV2 second amount of voltage
  • Fig. 1 is an illustration of a 4-wire resistor network constructed from two resistive planes
  • Fig. 2 illustrates a configuration of a touch screen having X and Y planes and a stylus pen for making contact between the X and Y planes;
  • Fig. 3 is a circuit diagram of an arrangement for polarizing the X plane of a touch screen and a measurement device for determining an X position of a stylus;
  • Fig. 4 is a circuit diagram illustrating an arrangement of measurement devices for determining whether a stylus is up or down;
  • Fig. 5A is a timing chart showing timing for determining an X position, a Y position and a PU/PD position of a stylus
  • Fig. 5B is a timing chart illustrating X and Y position readings in conjunction with PU/PD detections according to the present invention
  • Fig. 5 C is an embodiment of the present invention illustrating a current source and a capacitor for controlling voltage at an input to a measurement device under floating conditions;
  • Fig. 6 is an example of a 2- ⁇ lane touch screen constructed with pillars separating the planes and illustrating how one type of spike may occur
  • Fig. 7 is an example of pen readings and a spike
  • Fig. 8 is a circuit diagram including a measurement circuit according to the present invention.
  • Fig. 9 is a flowchart illustrating a procedure for making X-Y measurements and detecting stylus up according to the present invention.
  • Fig. 10 is an example of X-Y measurements including one valid X-Y measurement and two invalid measurements according to the processes of the present invention.
  • Variations in stylus pressure on a touch screen is one type of condition that can lead to spikes and inaccurate stylus position readings.
  • Variations in stylus pressure can be caused by any of screen imperfections, a screen surface having improper supports, or other problems. For example, when a user writes on a touch screen, and the stylus contacts a divot or other screen imperfection, the stylus may jump or momentarily loose contact with the screen, causing spikes in screen output. Improper supports for the touch screen can cause similar problems. Other conditions causing the stylus to lose pressure, or prevent contact of parallel planes of the touch screen, or any anomaly that prevents or inhibits formation of R5 connection between planes will also cause similar problems.
  • Fig. 6 includes an X-plane 600, a Y-plane 610, and support mechanisms 620 that maintain a non-contact distance 630 between the X and Y planes.
  • X-plane 600 When a stylus 200 is in contact with the upper plane (X-plane 600 in this example), the upper plane is bent toward the lower plane causing formation of the connection resistance R5.
  • Fig. 3 which illustrates a typical configuration for detecting a position of a stylus on a touch screen plane
  • the input to the measurement amplifier high impedance amplifier 310
  • the float condition occurs because the input is neither grounded nor does it have an applied voltage. Under float conditions, the input voltage is uncontrolled and can be at any value.
  • Fig. 5A it is seen that the X-plane measurement, Y-Plane measurement, and PU PD detections are performed at different times.
  • an X or Y plane measurement is made during a float condition (such as when the stylus is inadvertently D bumped D from contact with the touch screen, or other anomaly causing the X and Y planes to loose the connection resistance)
  • the X or Y measurement will be at an unknown value which will most likely result in an inaccurate reading with respect to a current intended position of the stylus.
  • the PU PD reading may have been made before the stylus loses contact and the X or Y plane readings taken. Thus a false position of the stylus is determined from a floating voltage rather than that controlled as applied through the connection resistance R5. If the PU/PD condition detected after the X and Y positions are measured, the stylus may have already regained contact with the touch screen, and the floating voltages again may be utilized as the stylus position although they represent float voltages.
  • Fig. 7 is a graph that illustrates example readings of X and Y positions under the above described conditions.
  • a set of proper readings 700 are acquired as a user draws a stylus across the touch screen. However, when a screen imperfection or other anomaly is encountered, the stylus loses pressure or contact causing connection resistance R5 to go to a high impedance state (essentially infinite). Without R5, the input to the measurement amplifier begins to float. The floating voltages are read as an inaccurate X-Y reading 710. At a point after contact is resumed, proper readings 720 continue.
  • the present inventors have determined that controlling the float voltage and validating X-Y position measurements with simultaneous PU/PD detection can solve the problems associated with inaccurate readings, particularly those due to float conditions.
  • Fig. 8 illustrates a circuit configuration for controlling float (drift) voltage at the input of a measurement amplifier once stylus pressure is released.
  • An external power source VD D is added which is set to charge capacitor(s) 830 at a known rate.
  • the power source V DD provides enough current to override any input leakage current or other conditions that result in a float or drift condition at the input of the measurement amplifier (ADC) 810.
  • the amount of current supplied by V DD is small enough that it does not significantly alter any voltages provided from valid X-Y measurements.
  • the error introduced by the current supplied by VDD through R6 will be compensated (cancelled) during a calibration routine performed by software during initialization of the touch screen.
  • a procedure tests V 300 voltages at predetermined locations on the touch screen.
  • the predetermined locations may be identified by an x displayed on the touch screen to which a user makes contact at the x, or the locations may be preset in factory test equipment.
  • the V 30 o voltages retrieved during calibration are then utilized to calibrate x and y distance equations based on subsequent V 300 voltages measured to determine pen (stylus) position.
  • This same type of calibration procedure compensates for any affect that the V DD /R6 current may have on the measurement process because the V DD R6 current is present during the calibration procedure.
  • the rate at which capacitor(s) 830 are charged is set to control float and not affect x-y measurements.
  • the capacitor(s) 830 include any existing filter capacitors and other capacitances of the circuit, including any added capacitances to adjust the rate of charge.
  • the rate of change of voltage as the capacitors charge is known, i.e., a fixed or calculatable capacitance value, or a charge rate determined via an initialization procedure, for example.
  • the value of charge in the capacitor(s) at any specific time can be detected via software as needed (from readings at amplifier 810, for example).
  • threshold values of VDD are set such that voltages above or below the thresholds are considered off the screen. For example, an 80% upper threshold indicates that any voltages measured higher than 80% of V DD is an invalid (or PU) measurement.
  • the invention may also be practiced with negative voltages.
  • the greater charge rate of the capacitors 830, due to charging from the current source would be in negative amounts (less than the non-floating voltages applied to the test line under valid operating conditions).
  • the absolute value of the voltage of the charging capacitors would be greater that the absolute value of an acceptable change in the test line voltage under valid operating conditions, both situations detectable via software.
  • Fig. 8 which places a resistor R6 between VDD and the input of the measurement amplifier 810.
  • R6 is set at a value much larger than Rl and R2. Since R6 is much higher than Rl and R2, the voltage at the ADC input is practically the same as V 300 .
  • the capacitor(s) 830 start charging to V D D when the stylus go PU.
  • the resistors (R6, etc.), and capacitor(s) 830 are chosen so that the highest acceptable (the fastest movements a D normal D user would do) change rate of X/Y position as caused by a userDs use of the stylus has a slower slope than that of the capacitor(s) charge curve.
  • Table 1 illustrates an example set of values for R6 and capacitor(s) 830.
  • Fig. 9 is a flowchart showing an example algorithm for making measurements and validating X-Y positions according to the present invention.
  • the method begins after a stylus is down (PD) interrupt is received.
  • the method is initialized by setting a stylus-up flag to false and a stylus-up count to zero.
  • an X-Y measurement mode is set up to acquire X-l and Y-l (X and Y positions).
  • the setup of the measurement mode consists of configuring hardware and measurement devices such that the X-Y position can be acquired.
  • the configuration shown in Fig. 8 is set up to measure a distance across an X-plane, and a similar configuration (refers) would be set up to measure the Y-plane.
  • First the X-plane distance would be measured, and then the Y-plane.
  • These measurements are performed by reading the N 30 Q voltage.
  • These readings are performed by setting silicon switches (via software) to connect measurement voltages and A/D converters (Schmidt trigger, for example).
  • the A/D converted value is read by software and utilized as either an X or Y measurement is made depending on the configuration of electronics and silicon switches set. Seperate X and Y measurement connections are made via the silicon switches which connect the measurement equipment to the touch screen circuitry (see Fig. 8, for example).
  • a wait period of Dt is implemented at step 920.
  • a procedure similar to those discussed with respect to step 910 is instituted to acquire positions X-2 and Y-2.
  • X-2/Y-2 represent a new measured position (or voltage of the charging capacitor) of the stylus from X-l/Y-1 to X-2/Y-2 during the wait period Dt.
  • K x and K y are both selected to represent a DnormalD drawing range.
  • Dt say for example, .01 seconds
  • K x would be set to a value that is equivalent or at some point above a max normal drawing range in the X-direction.
  • K y would be set at or above a max normal drawing range in the Y-direction.
  • both K x and K y values are simply one acceptable DnormalD drawing range K.
  • the stylus-up flag is set to zero, and a confirmed position X-Y of the stylus is set to X-l, Y-l (see step 950). However, if either X-2 or Y-2 are outside of the acceptable DnormalD drawing range, then the stylus-up counter is incremented by one at step 960.
  • the stylus-up is tested to determine if it is greater than a predetermined number the stylus-up counts which is set to indicate a stylus-up condition.
  • the stylus-up count threshold in this example (at step 970) is set to four.
  • other stylus-up count thresholds may be implemented. For example, higher stylus-up count thresholds may be required if, for example, the measurement and testing performed in steps 910 .. 940 are done at a more rapid pace or some other reason for which additional redundancy is needed. Conversely, a lower threshold may be acceptable if those steps are performed at a slower rate or under conditions where less redundancy is needed.
  • K (K x /K y ) and the stylus-up count for determining a stylus-up condition may be adjusted on these or any other factors including speed of the testing environment, a particular application on which the touch screen is being applied, or other design considerations.
  • a stylus-up flag is set to true at step 980. If the stylus-up threshold testing at step 970 indicates that the stylus is not yet up, the process is repeated starting at step 910 with measurement of new X-l and Y-l positions that are acquired.
  • a second wait Dt may be implemented (not shown, roughly equivalent to the Dt at step 920), compensated for additional time required for steps 930, 940, 950/960, and 970 to be performed, and the values X-2/Y-2 can be substituted for X-l/Y-1, and a second measurement starting at step 930 to get new values for X-2 and Y-2 may be performed.
  • Table 2 provides an example implementation of a software program for reading a touch location. As with other figures and example implementations presented herein, Table 2 is not intended to limit the present invention and is provided as one example implementation. The example is not intended as an executable or compilable code, but as an example of program flow consistent with the present invention. Table 2
  • BOOL isPen ⁇ p; do
  • Pen down Fig. 10 illustrates three sets of example measurements made and tested according to the process/method illustrated in Fig. 9.
  • the three sets of measurements correspond to (X-l/Y-1, X-2/Y-2) 1000, (X-3/Y-3, X-4/Y-4) 1010, and (X-5/Y-5, X-6/Y-6)1020.
  • the first measurement set, (X-l/Y-1, X-2/Y-2) is shown as having been acquired a Dt time period apart (via steps 910 and 930, for example). Comparing X-l/Y-1 to X-2/Y-2, the differences between the X-positions and
  • Y-positions indicated thereby are less than the values K x and K y , therefore indicating a valid position measurement at point X- 1/Y- 1 , since the gap between X-2/Y-2 and X- 1/Y- 1 is within the acceptable DnormalD drawing range (either reading (X1,Y1 or X2,Y2) or a combination of all readings may be utilized as the valid point, however, the last reading is considered to be the most accurate.
  • the stylus has apparently been released and then comes back in contact with the touch panel momentarily.
  • a position of the stylus is kept constant at X-l/Y-1 since only the first sample is valid.
  • the stylus position will remain at X-l/Y-1 until either a second valid sample is determined, or a stylus-up condition (after 4 or 5 invalid measurements) and the stylus-up flag is set to true (i.e., stylus position on screen does not change until next valid measurement).
  • the samples acquired will be very close together and any sample skip due to invalid measurements will not be noticeable, particularly when compared to invalid values that occur without applying the present invention.
  • Table 3 provides example code of a program for reading touch locations that includes a filtering routine. The filtering is applied independently to both the group of X samples and the group of Y samples. The resulting samples from this filtering are then used as the final X and Y coordinates. Table 3 z#define kPenupCount 8
  • the present invention includes a computer program product which is a storage medium (media) having instructions stored thereon in which can be used to control, or cause, a computer to perform any of the processes of the present invention.
  • the storage medium can include, but is not limited to, any type of disk including floppy disks, mini disks (MDDs), optical discs, DND, CD-ROMs, microdrive, and magneto-optical disks, ROMs, RAMs, EPROMs, EEPROMs, DRAMs, NRAMs, flash memory devices (including flash cards), magnetic or optical cards, nanosystems (including molecular memory ICs), RAID devices, remote data storage/archive/ warehousing, or any type of media or device suitable for storing instructions and/or data.
  • the present invention includes software for controlling both the hardware of the general purpose/specialized computer or microprocessor, and for enabling the computer or microprocessor to interact with a human user or other mechanism utilizing the results of the present invention.
  • software may include, but is not limited to, device drivers, operating systems, and user applications.
  • computer readable media further includes software for performing the present invention, as described above.

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  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Theoretical Computer Science (AREA)
  • Human Computer Interaction (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Position Input By Displaying (AREA)

Abstract

Selon l'invention, on peut améliorer l'immunité au bruit des écrans tactiles en réalisant des mesures consécutives de position X et Y (chacune de ces mesures s'effectuant à l'intérieur d'un Dt) et en testant les différences de position des mesures consécutives par opposition à une vitesse de changement maximale d'entrées valides. Un circuit de charge (830) est ajouté à un point de test (320) de manière à appliquer une tension avec un taux de variation supérieur au taux de variation maximal pour des entrées valides lorsque le point de test se trouve à l'état flottant. A l'état flottant, le circuit de charge contraint les mesures consécutives (810) à être reconnues comme non valides. Appliquées à des techniques pour écrans tactiles, les mesures non valides dépassant un seuil prédéterminé indiquent qu'une plume ou un stylet (200) se trouve dans un état sans contact. Les mesures non valides situées en dessous de ce seuil indiquent que la plume se trouve dans un état sans contact, ce qui devrait ordinairement provoquer une brusque variation (due à des tensions flottantes au niveau du point de test). Des mesures validées précédentes fournissent les positions de plume/stylet jusqu'à ce qu'une mesure valide suivante ou un état sans contact de la plume soit déterminé.
PCT/US2001/020935 2000-06-30 2001-07-02 Procede et dispositif destines a ameliorer l'immunite au bruit des ecrans tactiles WO2002003368A1 (fr)

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Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2945361A1 (fr) * 2009-05-05 2010-11-12 Magneti Marelli France Procede de validation et d'elimination de determination de donnees de coordonnees erronees pour dalle tactile resistive
US8294687B1 (en) 2012-02-23 2012-10-23 Cypress Semiconductor Corporation False touch filtering for capacitance sensing systems
US9007342B2 (en) 2009-07-28 2015-04-14 Cypress Semiconductor Corporation Dynamic mode switching for fast touch response
US9013429B1 (en) 2012-01-14 2015-04-21 Cypress Semiconductor Corporation Multi-stage stylus detection
US9154160B2 (en) 2006-11-14 2015-10-06 Cypress Semiconductor Corporation Capacitance to code converter with sigma-delta modulator
US9417728B2 (en) 2009-07-28 2016-08-16 Parade Technologies, Ltd. Predictive touch surface scanning
US9423427B2 (en) 2008-02-27 2016-08-23 Parade Technologies, Ltd. Methods and circuits for measuring mutual and self capacitance

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4570217A (en) * 1982-03-29 1986-02-11 Allen Bruce S Man machine interface
US5872561A (en) * 1997-03-31 1999-02-16 Allen-Bradley Company, Llc Fast scanning switch matrix

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4570217A (en) * 1982-03-29 1986-02-11 Allen Bruce S Man machine interface
US5872561A (en) * 1997-03-31 1999-02-16 Allen-Bradley Company, Llc Fast scanning switch matrix

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US9154160B2 (en) 2006-11-14 2015-10-06 Cypress Semiconductor Corporation Capacitance to code converter with sigma-delta modulator
US9423427B2 (en) 2008-02-27 2016-08-23 Parade Technologies, Ltd. Methods and circuits for measuring mutual and self capacitance
FR2945361A1 (fr) * 2009-05-05 2010-11-12 Magneti Marelli France Procede de validation et d'elimination de determination de donnees de coordonnees erronees pour dalle tactile resistive
EP2251773A1 (fr) * 2009-05-05 2010-11-17 Magneti Marelli France Procedé de validation de données de coordonnées déterminées par une dalle tactile resistive, et d'élimination de données de coordonnées erronées
US9007342B2 (en) 2009-07-28 2015-04-14 Cypress Semiconductor Corporation Dynamic mode switching for fast touch response
US9069405B2 (en) 2009-07-28 2015-06-30 Cypress Semiconductor Corporation Dynamic mode switching for fast touch response
US9417728B2 (en) 2009-07-28 2016-08-16 Parade Technologies, Ltd. Predictive touch surface scanning
US9013429B1 (en) 2012-01-14 2015-04-21 Cypress Semiconductor Corporation Multi-stage stylus detection
US9459749B1 (en) 2012-01-14 2016-10-04 Wacom Co., Ltd. Multi-stage stylus detection
US8294687B1 (en) 2012-02-23 2012-10-23 Cypress Semiconductor Corporation False touch filtering for capacitance sensing systems
US8766944B2 (en) 2012-02-23 2014-07-01 Cypress Semiconductor Corporation False touch filtering for capacitance sensing systems

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