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
  • G06F3/0416—Control or interface arrangements specially adapted for digitisers
  • G06F3/0418—Control or interface arrangements specially adapted for digitisers for error correction or compensation, e.g. based on parallax, calibration or alignment
• • 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
  • G06F3/0445—Digitisers, e.g. for touch screens or touch pads, characterised by the transducing means by capacitive means using two or more layers of sensing electrodes, e.g. using two layers of electrodes separated by a dielectric layer
• • G—PHYSICS
  • G06—COMPUTING; CALCULATING OR COUNTING
  • G06F—ELECTRIC DIGITAL DATA PROCESSING
  • G06F2203/00—Indexing scheme relating to G06F3/00 - G06F3/048
  • G06F2203/041—Indexing scheme relating to G06F3/041 - G06F3/045
  • G06F2203/04101—2.5D-digitiser, i.e. digitiser detecting the X/Y position of the input means, finger or stylus, also when it does not touch, but is proximate to the digitiser's interaction surface and also measures the distance of the input means within a short range in the Z direction, possibly with a separate measurement setup
• • G—PHYSICS
  • G06—COMPUTING; CALCULATING OR COUNTING
  • G06F—ELECTRIC DIGITAL DATA PROCESSING
  • G06F2203/00—Indexing scheme relating to G06F3/00 - G06F3/048
  • G06F2203/041—Indexing scheme relating to G06F3/041 - G06F3/045
  • G06F2203/04104—Multi-touch detection in digitiser, i.e. details about the simultaneous detection of a plurality of touching locations, e.g. multiple fingers or pen and finger

Definitions

• the present invention relates to a multi-zone capacitive sensing method and device.
• the field of the invention is more particularly but in a nonlimiting manner that of capacitive detection systems and tactile and non-contact human-machine interfaces.
• tactile or non-contact measurement interfaces as a human-machine interface for entering commands.
• These interfaces can in particular take the form of pads or touch screens. They are found for example in mobile phones, smartphones, touch screen computers, tablets, pads, PCs, mice, touch panels and giant screens.
• the measuring surface is equipped with conductive electrodes connected to electronic means which make it possible to measure the variation of the capacitances appearing between electrodes and the object to be detected in order to carry out a command.
• interfaces are tactile, that is, they can detect the contact of one or more object (s) of interest or control (such as fingers or a stylus) with the surface of the interface.
• document FR 2 756 048 by Rozière discloses a capacitive measurement method which makes it possible to measure the capacitance and the distance between a plurality of independent electrodes and an object in the vicinity.
• This technique makes it possible to obtain capacitance measurements between the electrodes and the objects with a high resolution and sensitivity, making it possible to detect for example a finger several centimeters or even ten centimeters apart.
• the detection can be done in the space in three dimensions but also on a surface, called measuring surface.
• control object can be considered to be at a reference electrical potential such as an electrical ground or earth.
• the electrodes are biased to an excitation voltage. Capacitive coupling is thus measured between these polarized electrodes and the object at the reference potential.
• the electrical circuit comprises a reference potential or an internal mass that is floating relative to the earth, since it is powered by a battery.
• this internal reference potential is brought back to earth or at least to the potential of the user's body.
• it is "seen" as being substantially at the internal reference potential or the device's ground potential.
• Such devices may for example be equipped with electrodes on the face opposite the screen and / or on the sides, in order to detect additional information on their environment, the manner in which they are held, etc.
• the problem which arises in this case is that, because of the floating nature of the on-board electronics with respect to earth, if measurement electrodes biased to an excitation voltage are in electrical contact or strongly coupled (capacitively) with for example the hand of the user holding the device, the entire body of the user is “seen” by the electronics as being substantially at this excitation potential. And in this case the control object which is for example its second hand is also “seen” as being substantially at the excitation potential of the electrodes. The capacitive coupling is then zero or very weak and the object is not detected or only at a short distance.
• Capacitive sensing techniques are also used to equip systems such as robots or mobile medical imaging devices (scanners, ...) to make them sensitive to their environment.
• the principle is the same: the capacitive coupling is measured between polarized capacitive electrodes at an excitation voltage and supposed environmental objects at an electrical reference potential, ground or earth.
• the electrodes are protected from undesired influences of the environment (parasitic capacitances) by disposing conductive surfaces with the same potential of excitement nearby.
• An object of the present invention is to propose a capacitive detection method and a device that make it possible to solve these disadvantages of the prior art.
• Another object of the present invention is to propose a capacitive detection method and a device which makes it possible to equip electrically floating apparatus with respect to a general mass or earth capacitive detection electrodes able to detect the approach of objects of interest so that the measurements are not or hardly affected by strong electrical couplings of certain electrodes with the mass or the earth.
• Another object of the present invention is to propose a capacitive detection method and a device that makes it possible to equip portable devices such as smartphones or capacitive detection electrode tablets on a plurality of faces so that the measurements are not not or little affected by strong electrical couplings of some electrodes with mass or earth.
• Another object of the present invention is to propose a capacitive detection method and a device which makes it possible to equip a plurality of capacitive detection electrode devices so that these devices are also able to detect each other mutually.
• a capacitive detection method implementing a plurality of electrodes able to allow the detection of objects in their vicinity by capacitive coupling, characterized in that it comprises a step of polarization simultaneously of at least a portion of said electrodes with different excitation potentials, which excitation potentials are generated with respect to a reference potential such that the dot product has a predetermined duration of at least two of these excitation potentials either zero or much less than the dot product of one and / or the other of these excitation potential with itself over said predetermined duration.
• the excitation potentials may correspond, for example, to time values of electrical excitation signals referenced to the reference potential, or else to differences in electrical voltage with respect to the reference potential.
• the excitation potentials generated may comprise:
• At least one excitation potential whose scalar product with a perturbation signal is minimized; at least one excitation potential substantially equal to the reference potential.
• the method according to the invention may further comprise a step of measuring the capacitive coupling of an electrode, comprising:
• a capacitive detection device comprising a plurality of electrodes adapted to allow the detection of objects in their vicinity by capacitive coupling, and further comprising excitation means able to polarize simultaneously. at least a portion of said electrodes with different excitation potentials, which excitation potentials are generated with respect to a reference potential such that the dot product has a predetermined duration of at least two of these excitation potentials either zero or much less than the dot product of one and / or the other of these excitation potential with itself over said predetermined time.
• the device according to the invention may furthermore comprise:
• the device according to the invention may further comprise means for polarizing at least one electrode:
• an apparatus comprising a capacitive detection device, and implementing the method according to the invention.
• the apparatus according to the invention can comprise, according to a first face, a display screen and first substantially transparent electrodes polarized at a first potential. excitation, and in a second face opposite to the first face of the second electrodes biased to a second excitation potential.
• the device can be in particular one of the following types: smartphone, tablet.
• the apparatus according to the invention may comprise a plurality of modules able to move relative to each other, each module comprising polarized electrodes at a different excitation potential from the other modules.
• FIG. 1 illustrates a first mode of implementation of the invention
• FIG. 2 illustrates a second embodiment of the invention
• FIG. 3 illustrates an electronic block diagram for implementing the invention
• FIG. 4 illustrates a timing diagram of the acquisition of measurements.
• FIG. 1 a first embodiment of the invention.
• This mode corresponds for example to the implementation of the invention in an electronic device 2 or a device 2 such as a telephone, a smartphone, a tablet PC, which comprises for example several screens, or a screen and sensitive areas such as buttons, ....
• the apparatus 2 which is shown in section is representative of a smartphone or a tablet PC. It comprises a first face with a display screen 4 equipped with first transparent capacitive electrodes 5 distributed (for example in a matrix arrangement) on its surface. These first electrodes 5 and their associated electronics make it possible to detect the position, the distance 3 and / or the contact of a control object 1 on the display screen 4.
• the control object 1 can be for example a finger of the user. Positions and distances detected are then trad uites in terms of commands by the control software of the human-machine interface of the apparatus 2.
• the apparatus comprises a first guiding surface 6 located behind the first electrodes 5 of the screen, between these electrodes 5 and the other elements of the apparatus 2. This first guard 6 is biased to the same potential
• the first electrodes 5 are energized electrically so as to avoid parasitic capacitive coupling between the first electrodes 5 and the internal elements of the apparatus 2, such as the electronics 12.
• the electrical excitation potential is defined with respect to a reference potential 13 which corresponds to the general mass of the electron 12 of the apparatus 2. It should be noted that in the case of a device When the portable battery is powered, in the absence of a galvanic connection or significant coupling with the earth, this reference potential 13 is floating relative to the earth.
• the apparatus 2 also comprises second electrodes 7 distributed
• These second electrodes 7 may be transparent electrodes superimposed on a second display screen, or electrodes simply equipping the housing of the device 2.
• These second electrodes 7 and their associated electronics make it possible to detect the position, the distance 3 and / or the contact of objects in their environment.
• the apparatus 2 further comprises a second conductive guard surface 8 located behind the second electrodes 7 of the screen, between these electrodes 7 and the other elements of the apparatus 2.
• This second guard 8 is polarized at the same electrical potential of the excitation that the second electrodes 7, so as to avoid spurious capacitive coupling between the second electrodes 7 and internal elements of the device 2, such as the electronic 12.
• the apparatus 2 may further comprise third electrodes 10, 11 on the side faces.
• the second face 14 and the side faces are privileged places to hold the device 2 in the hand, or place it on the palm of the hand, or to put it on a table or on the floor.
• the devices of the prior art which comprise only first electrodes 5 are designed so that when they are held or placed, the general mass of the electronics 12 is coupled (by electrical contact or by capacitive coupling) to the body of the electronics. the user and / or the support. Under these conditions it is possible to ensure that the reference potential 13 corresponds substantially to the potential of the body of the user and / or the earth. A finger or a conductive object held by the user then constitutes a control object 1 substantially at the reference potential 13 and can therefore be detected under the best conditions by the first electrodes 5.
• a device 2 as illustrated in FIG. 1 When a device 2 as illustrated in FIG. 1 is placed on a support 9 such as a hand or a table on the side for example of the second electrodes 7, it establishes a strong capacitive coupling between the support 9 and these electrodes 7. It follows that, compared to internal reference potential 13 of the apparatus 2, the support 9 appears as polarized at the excitation potential of the second electrodes 7. According to the same reasoning as above, the control object 1 is "seen” with respect to the reference potential internal 13 of the device 2 as being biased substantially at the same potential as the support 9, that is to say the excitation potential of the second electrodes 7. And if the excitation potential is identical for all electrodes as in the devices of the prior art, the control object 1 no longer generates capacitive coupling with the electrodes and can therefore no longer be detected (or at least only with very degraded performances).
• the solution implemented by the invention comprises the generation of different and substantially orthogonal excitation potentials in the mathematical sense for the first electrodes 5 and the second electrodes 7.
• the apparatus 2 may comprise third electrodes 10, 11 distinct respectively to the first and second faces 4, 14, as illustrated in FIG. 1.
• one of the third electrodes 10 may be at the excitation potential of the first electrodes 5, and one of the third electrodes 11 may be at the excitation potential of the second electrodes 7; the apparatus 2 may comprise only a third electrode 10 or 11 which covers at least a part of the lateral face.
• this third electrode may be at the excitation potential of the first electrodes 5 or at the excitation potential of the second electrodes 7. It may optionally be switched from one excitation potential to the other depending on information. from the measurements of the first and / or second electrodes.
• the third electrode 10 or 11 may also be at a different excitation potential from that of the first and second electrodes.
• the third electrodes may constitute a ring surrounding the apparatus 2, or comprise a plurality of electrodes distributed on these lateral faces.
• This mode corresponds for example to the implementation of the invention in modules 21, 22 movable relative to each other and with respect to their environment.
• This type of configuration can be found for example in robotics or in medical imaging devices with moving parts, such as scanners.
• each module 21, 22 has at least one capacitive detection zone 23, 24 with electrodes 5, 7 to avoid collisions and / or to make its movement without collision independent. It is also necessary that the capacitive detection zone 23 of a module 21 can recognize the detection zone 24 of another module 22 as a target object to avoid any risk of collision between these modules.
• the solution implemented by the invention comprises the generation of different excitation potentials and substantially orthogonal to the mathematical sense for the electrodes of the detection zones of the different modules 21, 22.
• the measurements of the various modules 21, 22 are managed by the same capacitive measuring device 25.
• the modules 21, 22 of FIG. 2 may also be provided with a plurality of detection zones or multi-face electrodes as shown in FIG. 1.
• the detection zones can be managed as explained below so as not to disturb each other between zones of the same module and / or different modules.
• the diagram presented comprises a plurality of measurement channels in parallel.
• Fig. 3 shows an example with two measurement channels.
• Each measurement channel allows the control and acquisition of measurements on one or a plurality of electrodes, as well as the generation of a distinct excitation potential for these electrodes.
• the detection electronics 12 comprises a so-called "floating" portion 32 (33), referenced to the excitation potential 42 (43), and which comprises the first measurement stages as close as possible to the electrodes.
• the excitation potential 42 (43) is generated by a time-varying voltage source (31) referenced to the reference potential 13 of the electronics 12.
• the floating electronics 32 (33) essentially comprises a charge amplifier 34 (35) referenced to the excitation potential 42 (43).
• This charge amplifier 34 (35) is input connected to a measurement electrode (7). It makes it possible to generate a voltage proportional to the charge accumulated in the electrode 5 (7), which depends on the coupling capacitance generated by the objects 1 (9) in the vicinity of the electrode 5 (7).
• the floating electronics 32 (33) also includes a multiplexer 44 (45) or a scanner which allows sequential "interrogation" of a plurality of electrodes 5 (7) with a single measurement channel.
• This multiplexer 44 (45) is designed in such a way as to connect the electrodes 5 (7):
• guard electrodes 6 behave like guard electrodes 6 (8), which makes it possible to avoid the appearance of parasitic capacitances with active electrodes connected to the input of the charge amplifier 34 (35).
• the output signal of the charge amplifier 34 (35) is referenced to the excitation potential 42 (43). It is converted by a differential amplifier 36 (37) into a signal referenced to the reference potential 13.
• the differential amplifier 36 (37) can be replaced by any other component for transferring a signal between electronic stages with different reference potentials.
• the measurement signal is then demodulated by a demodulator 38 (39) to produce a measurement 40 (41) representative of the distance or coupling of the electrodes 5 (7) with the object (s) 1 (9).
• the demodulator 38 (39) is digital.
• This detection principle allows measurements with very high sensitivity and very high precision because all the electronic elements close to the electrodes 5 (7) are referenced and / or polarized at the excitation potential 42 (43). Because of the structure of the charge amplifier 34 (35), the electrodes 5 (7) are also biased at the excitation potential 42 (43). So it can not appear parasitic abilities. In addition, biasing elements at the excitation potential 42 (43), including guard electrodes 6 (8), may be added in the vicinity of the measuring electrodes 5 (7) or their connection tracks to avoid appearance of parasitic capacitances with nearby elements subject to another potential.
• the electronics of FIG. 3 can be implemented in the device of FIG. 1 such that, for example,
• the first measurement channel controls all the first electrodes 5 of the first face 6, and the second measurement channel controls all the second electrodes 7 of the second face 14;
• the electrodes of a face 4, 14 are divided into zones and controlled respectively by several electronic measurement channels. This may improve the accuracy and independence of measurements in different areas;
• the lateral electrodes 10, 11 are respectively controlled by a first and a second measurement channel;
• the lateral electrodes 10, 11 are optionally connected to a first measurement channel or to a second measurement channel by switching means.
• the switching can be performed according to information from other electrodes;
• the lateral electrodes 10, 11 are controlled by a third electronic measurement channel
• the electronics of FIG. 3 can be implemented in the device of FIG. 2 of the kind q ue, for example, all the electrodes of a module 21, 22 are controlled pa r a same electronic measurement channel.
• the first measurement channel controls all the first electrodes 5 of the first module 21, and the second measurement channel controls all the second electrodes 7 of the second module 22.
• an object of the invention is to provide a method that allows the management of a multiplicity of detection zones, some of which may be in strong coupling with the user or the target.
• the set of electrodes of one or more detection zones is switched to the reference potential 13 when measurements with electrodes of another zone are acquired. detection.
• the detection zones are mutually interfering, either by coupling irect as in the case of FIG. 2, or by coupling with a control object as in the case of FIG. 1.
• this can be done advantageously by switching to the reference potential 13 u n excitation potential 43 for example.
• this can be done in particular by transforming the voltage source 31 into a short circuit, which amounts to extinguishing it or generating zero voltage.
• all the elements referenced to this excitation potential 43 are brought back to the reference potential 13, including the guard elements 8.
• This first variant of the invention can be implemented in the embodiment of FIG. 1 in the following way:
• the excitation potential 43 of the second electrodes 7 is switched to the reference potential 13, so that the second electrodes 7 of the second face 14 are placed at this reference potential 13;
• the excitation potential 42 of the first electrodes 5 is switched to the reference potential 13 so as to set the first electrodes 5 of the first face 4 to this reference potential 13, or measurements with the second electrodes 7.
• the device can be held and used on both sides, possibly in the same way.
• the first variant of the invention can also be implemented in the embodiment of FIG. 2 as follows:
• the excitation potential 43 of the second electrodes is switched to the reference potential 13, so that the second electrodes 7 of the second module 22 are put at this reference potential 13;
• first electrodes 5 of the first module 21 are sensitive of the same so as to the presence of the second module 22, including according to the detection zone 24, that the rest of the environment;
• the excitation potential 42 of the first electrodes 5 is switched to the reference potential 13 in such a way as to set the first electrodes 5 of the first module 21 at this reference potential 13, and then measurements are taken with the second electrodes 7 of the second module 22.
• This first variant of the invention has the drawback that the electrodes of the different detection zones must be activated and interrogated sequentially.
• V el (1) is the (digital) coupling signal obtained at the output 40 of the demodulator 38 of the first channel of the detection electronics, and which provides a measurement representative of the capacitive coupling or the distance between a first measuring electrode 5 and an object of interest 1.
• the coupling signal v ei (1) is updated with a time period greater than or equal to the accumulation time ⁇ ⁇ of the measurements in the demodulator 38, as will be seen below. It can correspond for example:
• U sl (t) is the analog load measurement signal, referenced to the reference potential 13, which appears at the output of the differential amplifier 36.
• the load measuring signal is demodulated in the demodulator 38 (for channel 1) to obtain the coupling signal V ei (1).
• This demodulation is a synchronous amplitude demodulation (baseband transposition and low-pass filtering) in which the excitation signal of the channel concerned is used as local oscillator 30, 31. It is done numerically. It comprises a term-to-term multiplication of the load measurement signal U if (k) with the excitation signal of the corresponding channel i and a summation of the terms of the product over a storage time duration ⁇ ⁇ , that is,
• N s ⁇ ⁇ / ⁇ ⁇ .
• the excitation signal can be written in the general form of a product of an amplitude term and a basic function bi (k which defines its temporal form, ie:
• V i (k) ⁇ V i ⁇ b i (k).
• the load measured on a first electrode 5 polarized at a first excitation potential V t (t) in the presence of an object of interest 1 can be expressed as follows:
• the capacitance C lt is the capacity to be measured between the electrode 5 and the object of interest 1 assumed at the reference potential 13.
• the capacitance C 12 is a parasitic capacitance due for example to a partial coupling between the object of interest 1 and second electrodes 7 (and guard electrodes 8) biased to the second excitation potential v 2 (t).
• the capacitance c lp is a parasitic capacitance due to couplings with the source of additional electrical perturbation.
• the source of additional electrical disturbance V p may be due for example to a connection of a portable device to a charger.
• This exciting potential of the stylus can then be chosen to contribute to measuring or improving the measurement with at least one of the measuring channels, or with several measurement channels sequentially. In this case, it may for example be synchronous with the excitation potential of the electrodes of at least one measurement channel.
• the measured load can be rewritten in a factored numerical form, either
• the first term of the general expression of the coupling signal V ei (Q, which depends only on the excitation potential i, corresponds to the value that it is desired to measure.
• Basic functions can be discrete functions that can take two values, such as + 1 and - 1.
• Basic functions can also be discrete functions that can take a more complete discrete set of values such as:
• the basic functions can be chosen so as to generate a periodic square signal pattern, or close to a sinusoid. Each basic function can then be essentially represented by a frequency f 1;
• the basic functions can be chosen in such a way as to minimize energy peaks, or to smooth the spectrum.
• the basic functions b t may be chosen so as to minimize the energy at low frequencies where the noise in 1 / f penalizes the system, and / or to avoid the energy at high frequencies for reasons of electromagnetic compatibility or of consumption ;
• the choice may be further oriented to minimize the scalar product term with a parasitic disturbance V p undergone, so as to minimize its influence.
• the basic functions b t can be pre-calculated and recorded in the device that has them in real time without additional calculation;
• b 2 (k) +1; +1; +1; +1; -1; -1; -1; ... repeated 199 times.
• b ⁇ k) +1; +1; -1; -1; +1; +1; -1; -1; ... repeated 199 times;
• b 2 (k) -1; +1; +1; -1; -1; +1; +1; -1; ... repeated 199 times.

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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)
• Electronic Switches (AREA)
• Position Input By Displaying (AREA)
• Measurement Of Resistance Or Impedance (AREA)
• Measurement Of Length, Angles, Or The Like Using Electric Or Magnetic Means (AREA)
• Investigating Or Analyzing Materials By The Use Of Electric Means (AREA)

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• 2013
  • 2013-04-15 FR FR1353371A patent/FR3004551A1/fr active Pending
• 2014
  • 2014-04-09 KR KR1020157031159A patent/KR101911135B1/ko active IP Right Grant
  • 2014-04-09 WO PCT/EP2014/057158 patent/WO2014170180A2/fr active Application Filing
  • 2014-04-09 CN CN201480027820.8A patent/CN105452998B/zh not_active Expired - Fee Related
  • 2014-04-09 US US14/784,264 patent/US10592046B2/en not_active Expired - Fee Related
  • 2014-04-09 EP EP14724650.8A patent/EP2987056A2/de not_active Withdrawn
  • 2014-04-09 JP JP2016508091A patent/JP6284623B2/ja not_active Expired - Fee Related

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