Method and apparatus for determining the position of an object on a given surface

Abstract

A method and a device for determining the position of an object on a given surface are disclosed. The method allows detecting the presence of an object on a measuring surface of an electronic device (1) and / or determining the position of an object on the measuring surface of the electronic device (1). The device comprises a medium (2) in the form of an electrode array for propagating oscillating signals and a measuring circuit (10). The method comprises the following steps: - providing one or more oscillating signals (Sr1, Sr2) at an input point, the input point being different and spaced apart from the electrode array in a detection area of ​​the measuring surface, - receiving one or more oscillating signals (Sout) that have passed through the electrode array in one or more output points, the electrode array defining a transfer function of the oscillating signals, the one or more output points being different and spaced apart from the electrode array in the detection area of ​​the measuring surface, - performing in the measuring circuit a measurement of the coupling or attenuation caused by the presence on the one or more oscillating signals through the electrode array of an object placed on the measuring surface, so as to determine the position of the object in the detection area of ​​the measuring surface depending on the modification of the transfer function of the electrode array.

Description

Technical Field

[0001] The invention relates to a method for detecting the presence of at least one object on a given measuring surface of an electronic device and / or for determining the position of at least one object on a given measuring surface of an electronic device.

[0002] The invention also relates to an electronic device for detecting the presence of at least one object on a measuring surface and / or for determining the position of at least one object on a measuring surface for implementing the method. Background Art

[0003] It is well known to detect the position of an object such as a user's finger on a screen such as a touch screen. Several techniques can be used for this purpose. These techniques are based, for example, on the measurement of resistance or capacitance, or also on the interruption of light (that is to say the masking of light), or on the attenuation of surface waves such as ultrasound.

[0004] These technologies can be classified into two categories. One category is based on the discrete sections of a given measurement surface, and the other category is based on the linear change of the amplitude along two axes X, Y. Capacitive sensor systems and those systems based on light generally fall into the discrete section category. All capacitive touch screens are made of arrays of rows and columns that are separated by an insulating layer and cross without contact, or are made of a group of discrete arrangement parts that are each individually connected to a detection circuit. In the prior art, generally, light-based systems also use light sources and sensors that are arranged relative to each other to form arrays of rows and columns. In these aforementioned systems, it is the activation information of the intersection between the discrete arrangement parts or columns and rows that gives the position. The screen of resistive or surface wave technology uses the linear change measured along two orthogonal axes to determine the contact position.

[0005] In the case of a touch screen of the capacitive type consisting of an array of electrodes, the detection of the activation of a touch key is based on measuring a modification in the frequency of a signal by connection to an oscillator, as described in patent EP1324162B1. This does not allow the use of the touch screen in any environment where the frequency could be modified before the activation of the key(s) by a finger on the touch screen, for example underwater. The frequency of the signal at each electrode can be varied or modulated to detect the activation of a touch key more reliably, but the identification of such an activation requires a less important processing for the table processor, which does not reduce the desired energy consumption.

[0006] In the case of arrays of capacitive touch electrodes spread on glass (indium tin oxide), it is always necessary to connect each capacitive sensor electrode to the measurement circuit via a connecting rail. Since each connecting rail also has a certain width, the arrangement of these different connecting rails inevitably causes the problem of wasted space, and sometimes there are one or two insulating layers for the passage of the connecting rails between the electrodes of the touch key and the measurement circuit. In addition, there are several parasitic capacitors or ground capacitors due to these electrical connections, and the measurement circuit must take this into account by defining and calibrating the interference caused by each parasitic capacitor for various measurements. This complicates the arrangement of such arrays of capacitive electrodes.

[0007] Patent application EP0838737B1 describes a set of capacitive sensor electrodes arranged close to each other under a watch glass. Each electrode is connected to a measuring circuit via an electrical conductor. Therefore, as mentioned above, all electrodes are connected via electrical conductors, which causes the problem of wasted space in the watch housing, and in addition there are several parasitic capacitors or grounding capacitors. Summary of the invention

[0008] Therefore, the object of the present invention is to overcome the disadvantages of the prior art by providing a method for detecting the presence of at least one object on a measuring surface of an electronic device and / or determining the position of at least one object on a measuring surface of an electronic device by analyzing the influence of the object on an oscillating signal propagating through a beneficial medium and without congestion of a large number of electrical connections of the electronic device.

[0009] To this end, the present invention relates to a method for detecting the presence of at least one object on or near a measuring surface of an electronic device and / or determining at least one position of at least one object on or near a measuring surface of an electronic device, the method comprising the features defined in independent claim 1.

[0010] Specific steps of the method are defined in dependent claims 2 to 10 .

[0011] The advantage of the method lies in the fact that the oscillating signal propagation medium defines a transfer function of the oscillating signal that varies depending on the position of an object (such as a finger) on the measuring surface of the electronic device. Thus, the coupling or attenuation caused by the presence of at least one object (such as a finger) on or near the measuring surface is measured by the output point of the measuring circuit to determine the position of the object. The output signal can be digitized and controlled relative to stored position parameters, in particular after a learning phase using a computer machine for learning the determined position. It can be a propagation medium that is the glass of a portable instrument, in which the light beam is reflected between the upper measuring surface and the lower surface. In the case of ultrasonic signals, for example using surface waves, the propagation medium can also be a measuring surface on a watch glass or through the thickness of the glass using piezoelectric electrodes arranged on the lower or upper surface of the watch glass.

[0012] Advantageously, the measuring circuit of the electronic device remains the same in any type of electronic device without affecting the shape, size of the propagation medium and the shape, size of the detection area on the measuring surface. The learning and configuration phases of the measuring circuit are the same, using electrical or optical or ultrasonic or electromagnetic oscillation signals. Such an electronic device can easily equip any type of portable instrument, such as, for example, an electronic watch or an electromechanical meter.

[0013] Advantageously, if the propagation medium is an array of capacitive sensor electrodes, this is no longer based on segments divided into rows and columns nor on discrete areas, but on the variation of the propagation function along a given axis. Several electrodes are left in a floating state without being directly connected to the measurement circuit via conductive tracks, since only some electrodes at the periphery of the electrode array in the form of a matrix are connected via conductive tracks for providing an oscillating signal at the input and receiving the signal to be measured at the output.

[0014] Advantageously, the electronics with the capacitive electrode array may be integrated into an electronic or electromechanical meter.

[0015] Advantageously, the propagation medium may be the glass of the portable instrument for the light beam to be reflected between the upper measuring surface and the lower surface.

[0016] Advantageously, the propagation medium may be the measuring surface of the glass or may be through the glass using piezoelectric electrodes arranged on the lower or upper surface of the glass to transmit the ultrasonic signal, for example using surface waves.

[0017] Advantageously, the electronic device can be configured after a learning phase in such a way that it recognizes a person's signature or recognizes a character drawn on the measuring surface. For this purpose, any movement of a finger on the measuring surface is determined using a time component and using configuration parameters that take into account the values ​​X and Y and the time component.

[0018] To this end, the invention also relates to an electronic device for implementing a method for detecting the presence of an object on a measuring surface and / or determining at least one position of an object on a measuring surface, comprising the features defined in independent claim 11 .

[0019] Particular embodiments of the electronic device are defined in the dependent claims 12 to 22 . BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The invention will be described in more detail below using the accompanying drawings given by way of non-limiting examples, in which:

[0021] - Figure 1 Partially showing an electronic device according to the invention for detecting the presence and / or determining the position of at least one object on a given measuring surface by means of the principle of variation of an oscillating signal through a propagation medium, said propagation medium defining a transfer function of the oscillating signal,

[0022] - Figure 2 represents an embodiment of an electronic device according to the invention having an array of capacitive sensor electrodes in the form of a matrix connected to a measuring circuit for determining the position of at least one object on a given measuring surface,

[0023] - Figure 3 shows the specific propagation form of two orthogonal input signals for the method according to the invention measured at an output point in the propagation medium, depending on the modified transfer function of the signal-to-interference ratio relative to the position of the measuring point,

[0024] - Figure 4 A simple equivalent model of a capacitive sensor electrode array in a matrix form using a measuring amplifier structure to define a propagation medium according to the present invention is shown.

[0025] - Figure 5 A first embodiment of a capacitive sensor electrode array as a propagation medium according to the present invention is shown, for which each electrode is comb-structured so as to partially interlock with each adjacent electrode,

[0026] - Figure 6 A second embodiment of a capacitive sensor electrode array as a propagation medium according to the present invention is shown, which consists of square-shaped electrodes,

[0027] - Figure 7 A third embodiment of a capacitive sensor electrode array as a propagation medium according to the present invention is shown, which consists of electrodes in a hexagonal shape,

[0028] - Figure 8The connections shown form the part provided for measuring the Figure 3 An embodiment of a measurement and excitation device of a part of a measurement circuit of an electrode array of an oscillating signal is shown,

[0029] - Fig. 9 A first embodiment of a part of an electronic device according to the invention for determining the position of at least one object on a given measuring surface in a propagation medium such as glass for propagating optical signals is shown,

[0030] - Fig.10 A second embodiment of a part of an electronic device according to the invention for determining the position of at least one object on a given measuring surface in a propagation medium such as glass for propagating light signals from two light sources is shown, and

[0031] - Fig.11 A third embodiment of a part of an electronic device according to the invention for determining the position of at least one object on a given measurement surface in a propagation medium such as glass for propagating a combined optical signal from beams from two light sources is shown. DETAILED DESCRIPTION

[0032] In the following description, all components of an electronic device for detecting the presence of at least one object on a given measuring surface and / or determining the position of at least one object on a given measuring surface are described only in a simplified manner, the components of the electronic device being familiar to a person skilled in the art.

[0033] Figure 1 Partially shown is an electronic device, in particular for implementing a method for detecting the presence of at least one object D on or near a given measuring surface of the electronic device and / or determining the position of at least one object D on or near a given measuring surface of the electronic device. Figure 1 There is no object on the left side of Figure 1 On the right side of the object D is placed at or near a position of the measuring surface in the detection area of ​​the electronic device. Preferably, the electronic device may be equipped with a portable instrument such as an electronic watch or an electromechanical meter.

[0034] At least one oscillating signal Sin is provided to at least one input point of a first portion of an oscillating signal propagation medium 2. Each oscillating excitation signal may be at a frequency of the order of 400 kHz but is not necessarily limited to this value. The propagation medium 2 defines a transfer function for the (multiple) oscillating signals, so that the amplitude or any other measurable properties of the (multiple) oscillating signals depend on the local properties of the medium. The oscillating signal Sin may pass through the propagation medium 2 and may be received or picked up at one or more output points Sout, which are different and spaced apart from a second portion of the propagation medium 2 in the detection region of the measurement surface.

[0035] In this Figure 1 In FIG. 1 , four output points Sout disposed in four corners of the propagation medium 2 are shown to cover the entire detection area of ​​the measurement surface, but are not limited to more or less output points that output the measurement signal Sout. Figure 1 As shown on the right side of , the coupling or attenuation caused by the presence of at least one object D (such as a finger) on or near the measuring surface is thus measured on the oscillating signal through the medium using the output point. Note that Figure 1 The oscillation output signal Sout on the right side of the Figure 1 The oscillation output signal Sout has a reduced amplitude compared to the right portion of the left side. Figure 1 The oscillating output signal Sout on the right and left parts of the medium varies in amplitude relative to the oscillating input signal Sin, but does not vary due to the presence or absence of the object D on the measurement surface. Therefore, it is possible to note the influence of the object D on the oscillating signal transmitted from left to right by modifying the transfer function of the medium.

[0036] As indicated above, the attenuation of the oscillating signal can be measured in the electronic device even when no object is present on the measuring surface. In this case, the attenuation of the oscillating signal (that is to say the reduced amplitude of said oscillating signal picked up) depends on the distance between the input point of the oscillating signal Sin and the output point for the signal to be measured Sout.

[0037] It should be noted that an oscillating signal such as a reference oscillating signal can be an electrical signal, or an optical signal, or an ultrasonic signal (surface wave, etc.), or an electromagnetic signal. The oscillating signal can also be a signal created by mixing an ultrasonic pressure wave and a local electrical feature or an optical feature (capacitance modulated by a change in thickness associated with the propagation of ultrasonic waves, or modulated optical FTIR coupled by the surface angle of the ultrasonic wave). In the case of an optical signal, the propagation medium can be directly a watch glass, where the light beam is reflected between the upper surface and the lower surface, and the upper surface is the measurement surface. In the case of an ultrasonic signal, for example, using a surface wave, the propagation medium can also be a measurement surface on the watch glass or through the thickness of the glass using a piezoelectric electrode disposed on the lower or upper surface of the watch glass.

[0038] Due to the different measurement output points of the modified oscillating signal Sout during its path in the propagation medium 2, the measuring circuit ( Figure 1 The electronic device (not shown) is able to determine the position of the object D in the detection area of ​​the measuring surface, depending on the modification of the medium transfer function. However, since it may be intended to equip the electronic device with an electronic or electromechanical meter with low energy consumption, the stage of learning the different positions of the object D on or near the measuring surface can be performed by a learning machine or device communicating with the electronic device. In the case of a possible subsequent learning phase (which is after the product manufacturing phase), wireless communication can be envisaged with the aim of simplifying the user interface and allowing specialized learning for a given user. A mobile phone ("smartphone") can be used, which has an adapted program that guides the user, for example, regarding the different patterns to be performed on the touch sensor (that is to say on the measuring surface).

[0039] This learning phase allows the exact position in X and Y of the object D on the measuring surface to be determined by the learning machine (for example using a robotic positioning system to precisely define the position XY), following the different positions on which the object D is located depending on the oscillation signal measured in the measuring circuit and transmitted to the learning machine. The different values ​​in X and Y for the different positions on the measuring surface determined by the learning machine are transmitted and stored in the memory of the electronic device. Once this learning phase has passed, the electronic device can easily perform subsequent determinations of the position of any object placed on or near the measuring surface.

[0040] Of course, it is possible to provide several oscillating signals Sin at different input points spaced apart from the first part of the propagation medium 2 so as to be received by one or more output points Sout of the second part of the propagation medium 2 for measuring the position of the object D on the measurement surface. The different input points or different output points of the oscillating signal are spaced apart to allow a good distribution, preferably at the periphery of the propagation medium 2, so that any position of the object in the detection area of ​​the measurement surface can be accurately determined by the measuring circuit. The detection area is usually defined between the input points and the output points or also covers them. The presence of an object such as a finger on the measurement surface affects the local properties of the propagation medium 2, causing some modification of the properties of the received signal relative to its position.

[0041] In the remainder of this description, only propagation media in the form of capacitive sensor electrode arrays for touch screens of electronic devices will be mentioned. Such electrode arrays are generally arranged under a non-conductive support or a non-conductive protective screen, for example connected to a watch glass. However, depending on the type of oscillating signal used to measure the position of an object on the measurement surface, any other propagation medium may be considered. In addition, various measurements related to the transfer function of the medium used may be phase, amplitude or also the travel time of the signal in the medium.

[0042] Figure 2 An embodiment of an electronic device 1 is shown comprising an array of capacitive sensor electrodes 2 defining an oscillating signal propagation medium, the array of capacitive sensor electrodes 2 being connected to a measuring circuit 10. According to the new detection concept, the array of electrodes 2 in the form of a matrix no longer comprises a set of discrete measurement points, but as a discrete or continuous matrix in which only a few different points are measured. The electrode array takes the form of a chessboard in which the electrodes 2 are neatly grouped together and finely spaced from each other.

[0043] Instead of measuring local capacitance values ​​to determine position, the new electrode array 2 linked to the measurement circuit 10 operates with an overall measurement of the transmission properties relative to a set of possible paths. The presence of a finger as an object affects the local properties of the propagation medium by causing certain modifications in the properties of the oscillating signal received at the various outputs.

[0044] The electrode array 2 thus comprises a major part of capacitive electrodes 2 which are of the floating type, that is to say which are not connected to the measuring circuit 10 or to neighbouring electrodes by means of conductive tracks. Only some of the electrodes, usually these electrodes at the periphery of the electrode matrix, are used to receive one or more oscillating input signals Srn, Srn+1 and to provide one or more measurement signals at the output Soutn in order to determine the position of an object placed on the electrode array by means of the measuring circuit 10. Only the tracks for connecting to the electrodes 2 for measurement are connected to the measuring circuit 10.

[0045] As in Figure 2 As shown in this embodiment of the present invention, different excitations and measurements can be exchanged at different input ports and output ports. At a given time, two oscillating input excitation signals Srn and Srn+1 are prepared, each signal is provided to a corresponding electrode 2, while being sufficiently spaced apart from each other. The two electrodes 2 are located at the periphery of the first part of the oscillating signal propagation medium. Preferably, a first oscillating excitation signal Srn and a second oscillating excitation signal Srn+1 are prepared, the first oscillating excitation signal Srn is an analog broadband signal, and the second oscillating excitation signal Srn+1 is an analog orthogonal signal. Therefore, it can be seen that (multiple) input signals propagate in the transmission medium to the output of the capacitive electrode array (but here to the output electrode 2) to provide a measurement signal Soutn. The output electrode 2 is located in the second part of the propagation medium and is preferably far away from the two input electrodes so as to be able to cover most of the detection area of ​​the measurement surface of the electronic device 1. The triangle connecting the electrodes 2 of the input Srn, Srn+1 signals and the electrodes 2 of the output Soutn signal covers part of the detection area. The measurement circuit 10 must be responsible for detecting the presence of at least one object on or near the measurement surface on the one hand, and also for determining the position of the object on the electrode array.

[0046] Since a greater number of excitation signals can be considered, the excitation signals are given the designations Srn (instead of Sr1) and Srn+1 (instead of Sr2) spontaneously. The same is true for the designations Soutn (instead of Sout) for the output measurement signals since a greater number of output measurement signals can be considered.

[0047] In order to provide the excitation signals Srn and Srn+1 and to receive the output signal(s) Soutn, the measuring circuit 10 essentially comprises a measuring and excitation device 11. The measuring circuit 10 also comprises a neural network 13 which receives the successive measurement signals from the measuring and excitation device 11 in order to determine the position X and the position Y of the object on the measuring surface. However, for the measuring device 1, an initial phase of learning the position of the object on the measuring surface is performed beforehand. For this purpose, the measuring circuit 10 comprises a communication controller 12 for communicating by wireless data signals Scom1 or by data signals Scom2 for direct connection to a learning machine 16.

[0048] As explained below, the determination of the exact position of an object, for example a finger, on the array of electrodes 2 is performed by training a neural network by a computer machine 16 to define the positions in X and Y of the array on which the finger is located. Subsequently, the exact position of the finger is determined by the neural network 13 included in the measurement circuit 10, in response to several measurement signals Sout digitized taking into account the variation of each output signal according to the position of the finger on the array. The different values ​​in X and Y determined by the learning machine 16 for different positions on the measurement surface are transmitted and stored in a memory 14 of the measurement circuit 10. This memory 14 may be a FLASH type memory which provides the synaptic weights associated with the values ​​in X and Y transmitted by the learning machine 16 when determining the position of the neural network 13.

[0049] It should be noted that the electronic device 1 may also be able to give additional output values, which represent, for example, the angle of inclination of a finger on the electrode array matrix. In addition, provision is made to be able to determine the movement of a finger D on the measuring surface of the electronic device 1 over time in order to produce a signature or alphabetic character, as explained below at the end of this description. In this case and after a learning phase, time must be taken into account to determine the trajectory on the measuring surface in the electronic device 1. Therefore, in addition to the different values ​​of the position of the object on the measuring surface in X and Y, which are transmitted by the learning machine and stored in the memory of the electronic device 1, the values ​​of the time or period of the movement of the finger on the measuring surface must also be learned by the electronic device 1. The device may include a time base or oscillator for timing operations.

[0050] The electronic device 1 is provided, for example, to equip a watch, such as an electronic wristwatch or an electromechanical wristwatch, and the electrode array 2 can be arranged under a non-conductive protective screen, not shown, the upper surface of which is used as the measuring surface of the electronic device 1. Preferably, the array of transparent electrodes 2 on glass (produced, for example, by diffusion of indium tin oxide) can be arranged directly under the watch glass, or also under a transparent protective screen of small thickness mounted on the watch glass, as indicated in the patent EP 2988180 B1 incorporated herein (cf. Figure 2 , paragraphs

[0028] and

[0029] ).

[0051] exist Figure 2In the embodiment of the present invention, the electronic device 1 may also comprise a controller 12 for communicating the data signal Scom1 or Scom2 in the measuring circuit 10. This controller 12 may be used to allow a learning phase specific to a given user (e.g. a personalized signature) to be performed through this simplified connection to an external computing unit (e.g. a mobile phone "smartphone" or a tablet). A wired communication Scom2 with an industrial learning machine may also be established during an initial learning phase ("machine learning") performed during the production of the product 16.

[0052] This initial learning phase is therefore necessary for the electronic device 1 to use the principle of "machine learning", that is to say, the position determination based on the measurement of the signal oscillating through the propagation medium 2 performed by a computer machine using a non-regressive algorithm. The digital measurement values ​​from the electronic device 1 are thus transmitted to the computer machine 16. Several different digital values ​​are usually transmitted for different positions of the object on the measurement surface.

[0053] The initialization phase is advantageously carried out outside the device 10 and in a powerful computer machine. The consumption of the measurement circuit can thus be reduced to the simple consumption of the neural network, the various synaptic weights being defined during a learning phase and then stored in a non-volatile memory of the measurement circuit 10. The measurement circuit 10 thus behaves like a filter that can be parameterized for any geometry of the floating electrode matrix (or of the propagation medium in the absence of replacement of the electrodes). The determination of the exact position of an object (for example a finger) on the electrode array 2 is performed by training the neural network by a computer machine to define the positions in X and Y of the array on which the finger is located. The exact position of the finger is then determined by the neural network comprised in the measurement circuit 10 in response to several measurement signals Sout digitized taking into account the variation of each output signal according to the position of the finger on the array.

[0054] It should be noted that the computer machine may simply be a mobile phone 16 as shown, which has wireless communication of the signal Scom with the connected electronic device 1 with a touch-sensitive crystal. The communication between the electronic device 1 and the mobile phone 16 may be established, for example, in the near field.

[0055] At the end of the learning phase, data such as synaptic parameters and weights of the neural network are stored in a memory of the circuit 10 of the electronic device 1. Once parameterized with the synaptic weights determined during the learning phase, the electronic device 1 can easily determine the placement position of the finger on the array of electrodes 2 inversely to the shape of each output signal Sout. A simplification of the position calculation is thus obtained in the measurement circuit 10 by determining the position after the learning phase without major expenditure.

[0056] It should also be noted that, in the specific case of a capacitive touch device, the present invention proposes to create a medium conducive to the propagation of oscillating electrical signals and in compliance with the above criteria by juxtaposing conductive electrodes 2, which have a low space requirement between each electrode and are isolated in the electrode array. All electrodes define a detection area of ​​the measurement surface. In this way, the oscillating signal can propagate from the conductive electrode 2 to its neighboring electrodes through the edge capacitor effect. The presence of an object such as a finger at a small distance above the measurement surface (typically the thickness of the non-conductive protective screen covering the electrodes) exerts a combined effect of attenuation (by coupling to ground) and enhancement (by increasing the permittivity of the edge capacitance) on the array of electrodes 2, which affects the transfer function of the oscillating signal between different measurement points and injection points, and this varies depending on the position of the finger.

[0057] Figure 3 A specific form of propagation of two orthogonal input signals Sr1 and Sr2 for the method is shown, which are measured at an output point Sout in the propagation medium. This measurement principle is similar to that already described with reference to the method for detecting the presence of at least one object on or near a given measuring surface of an electronic device and / or determining the position of at least one object on or near a given measuring surface of an electronic device. Figure 1 The described one is different because it seeks to obtain a certain robustness against variations in the natural noise. There is therefore a first excitation signal Sr1, which is a broadband analog signal, provided to a first electrode 2 of the array, and there is interference provided by a second electrode 2 of the array spaced apart from the first electrode. This interference signal Sr2 is chosen to be orthogonal to the excitation signal Sr1. Thus, it is then possible to define a signal-to-interference ratio that is much more constant and is defined relative to variations in the natural noise when the overall signal-to-noise ratio (SNR) is sufficiently greater than the limits of the electronic device. As in Figure 3 As shown in , there is a modification in the signal-to-noise ratio relative to the position of the measuring point.

[0058] As will be Figure 8As explained in , the measurement output signal Sout is converted into a digital signal by an ADC converter. The broadband signal is then projected to give a transfer function fct(A2 / A1), where A1 is the attenuation of the excitation signal Sr1 and A2 is the attenuation of the orthogonal signal Sr2 at the measurement point. The influence of a finger placed in the detection area between the input Sr1 and the output Sout can be determined. The orthogonal signal is also projected to give a transfer function fct(A1 / A2). Subsequently, the two functions fct(A2 / A1) and fct(A1 / A2) are subtracted to give an output digital measurement signal Fct(A1, A2) of the measurement circuit, which is on N bits and can be transmitted to a learning machine in an initial learning phase as previously described.

[0059] Figure 4 Only a simple equivalent model of an array of capacitive sensor electrodes 2 in matrix form and defining a propagation medium is shown, which has a structure of a measuring amplifier 4 connected to the output of the array. The input resistor Rin is connected from the array to the negative terminal of the amplifier 4, while its positive input is linked to ground. The measuring resistor R2 connects the negative terminal of the amplifier 4 and its output. A parasitic capacitor Cp linked to ground is maintained at the connection node between the input resistor Rin and the measuring resistor R2.

[0060] The array of electrodes 2, called floating electrodes Cf (that is to say not connected), can be approximated in simulation as an array of mutual capacitors arranged in a comb (edge) shape, with a matrix of capacitors to ground Cb. When this simple model is completed with the position of the finger, two main parameters are affected. On the one hand, the electrodes touched or approached by the finger obtain larger capacitance to ground values, and on the other hand, the electrodes directly close to the finger obtain larger mutual capacitance values ​​due to the high ε value of the finger tissue (water, ε = 80).

[0061] The resistance equivalent to the finger model scale is estimated to be in the megohm range, but the actual situation may be more complicated. However, the two effects listed below achieve complementary effects, that is, the increase in the capacitance value to ground reduces the coupling from the source to the measurement point, and the increase in marginal capacitors couples more signal from the source to the measurement point.

[0062] A number of parameters characterize the structure of the array used. Consideration must be given to a number of electrodes greater than at least 9 electrodes, such as 16, 20, 50, 100 or more electrodes, their shape and size less than 1 mm, with a distance separating them of, for example, 50 μm or 35 μm or even less, with a distance to a given ground plane. Further, it soon becomes apparent that the input capacitors of the detection structure or preamplifier reduce the signal level. This is simply due to the capacitance divider structure between the teeth of the comb-shaped electrodes and the capacitance measurement to ground. For this reason, an inverting 4-amplifier structure is used.

[0063] Compared with other possible approaches, Figure 4 This structure has some advantages, which are listed below:

[0064] -The high impedance array "sees" a resistor that achieves very low parasitic capacitance to ground values, especially when discrete components are used to build the input sense amplifier.

[0065] – The corresponding integrated structure allows reducing the ESD protections and even eliminating them on the input electrodes.

[0066] -The overall structure obtains a high-pass function.

[0067] - Due to the very high impedance of the array (only marginal capacitors in parallel with the ground capacitor), the same input electrode can become an excitation electrode by sending the excitation signal behind a series resistor.

[0068] As such, it should be noted that several electrode array configurations in matrix form have been tested. Figure 5 , Figure 6 and Figure 7 The electrode array shown in FIG.

[0069] Figure 5 A first embodiment of a capacitive sensor electrode array as a propagation medium is shown for which each electrode has a comb-shaped structure to partially interlock with each adjacent electrode. Therefore, only four electrodes 2, 2', 2", 2''' are shown, each of which includes an X-shaped or cross-shaped base 2b and extending from the X-shaped base and sized to form four small square teeth 2p from each branch of the base 2b. The four small square teeth 2p form each square-shaped electrode with the base 2b. Each small square tooth of each electrode interlocks with another small square tooth of an adjacent electrode.

[0070] Of course, more than four electrodes are actually needed to create an electrode array. Such an electrode array with low fringe capacitance values ​​results in the highest signal variation dynamics relative to the position of a finger on the array. This is simply due to the fact that the finger-to-ground capacitance value dominates in the observed frequency range. In addition, the finger grounding effect (in the range of 1 pF) becomes much larger when the coupling edge is reduced.

[0071] Figure 6 A second embodiment of a capacitive electrode array is shown. In this case, the electrode array is formed by a set of square-shaped electrodes 2 in the form of a matrix. Of course, it is sought to reduce the space between each adjacent electrode to define the array of electrodes 2 of the electronic device.

[0072] Figure 7 A third embodiment of a capacitive electrode array is shown. In this case, the electrode array is formed by a set of electrodes 2 having a hexagonal shape and distributed as a honeycomb. Of course, it is sought to reduce the space between each adjacent electrode to define the array of electrodes 2 of the electronic device.

[0073] Figure 8 An embodiment of an electronic device 1 is shown, which has an array of electrodes 2 (matrix of capacitive sensors) and is provided in part for measuring the above reference Figure 2 and Figure 3 The measuring circuit 10 of the oscillating signal is described. The array of electrodes 2 receives a first excitation signal Sr1 and a second orthogonal signal Sr2, each signal being provided to a corresponding electrode 2. The array of electrodes 2 provides a measurement output signal Sout based on the variation of the oscillating signal depending on an object or finger placed on the measuring surface, as explained previously.

[0074] In the measuring circuit 10, the output signal Sout is converted into a digital signal in an analogue-to-digital converter 21 with, for example, 1-bit gain. With digital signal processing one seeks to obtain the lowest possible power dissipation during the measurement and to keep the analogue-to-digital converter 21 as simple as possible.

[0075] After the digital conversion of the output signal Sout, a signal projection is performed via a complex projection operator 22, which receives the digital signal from the unit 25 of the excitation signal prototype of the first excitation signal Sr1 which becomes the digital signal. This simple projection method actually corresponds to a simple bandwidth filtering when the excitation signal has a constant frequency. However, it is not recommended to use a constant frequency, because interference with a frequency similar to the excitation signal may corrupt the measurement. For this reason, the frequency of the signal is swept during the measurement, which allows to eliminate the problem of fixed potential interference.

[0076] In the measurement circuit 10, the projection concept is done instantaneously and does not require any acquisition memory signal, and a simple multiplier structure followed by an integrator is sufficient to provide the projected result. In order to achieve good robustness against phase variations, a complex signal projection using a complex projection operator 22 is used. The output of this complex projection operator 22 is received by a phase accumulator Cplx 23 (integrator), generating the real and imaginary parts of the digital projection signal.

[0077] It is during the initial learning phase of the electronic device 1 that each N-bit digital signal at the output of the accumulator 23 is successively transmitted to the learning machine.

[0078] The accumulator 23 is also connected to a logic control unit 24, which can be a processor or more precisely a microcontroller, in which a memory can also be provided, for example, to store all configuration parameters (synaptic weights) after an initial learning phase. All complex values ​​of the digitized output signal of the measuring circuit are used for the learning phase together with the associated position XY and are archived on an external hard disk in a database (in preparation for the learning phase).

[0079] The logic control unit 24 comprises a phase generator. The phase generator allows the generation of the excitation signal and the projection signal.

[0080] The control logic unit 24 sends the phase signal to the unit 25 of the excitation signal prototype of the first excitation signal Sr1 which becomes a digital signal and the unit 26 of the excitation signal prototype of the second excitation signal Sr2 which becomes a digital signal orthogonal to the first signal Sr1. The output of the unit 25 of the excitation signal prototype of the first excitation signal Sr1 is converted in the first digital-to-analog converter DAC27 to provide the first oscillating excitation signal Sr1 to the electrode array 2. The output of the unit 26 of the excitation signal prototype of the second excitation signal Sr2 is converted in the second digital-to-analog converter DAC28 to provide the second oscillating signal Sr2 orthogonal to the electrode array 2.

[0081] As an alternative to an electrode array as a propagation medium, Figures 9 to 11 Three embodiments of an electronic device for determining at least one position of an object on a measuring surface in which a propagation medium is adapted for transmitting a light signal (optical signal) are shown in part. The propagation medium is a glass 32 of a portable instrument, such as, for example, a watch glass. In order to determine the position of an object (such as a finger D) on the measuring surface, the principle of attenuated total internal reflection (FTIR or "frustrated total internal reflection") in optics is used. This interesting optical property is generally used to completely cut off reflected light internally in an orthogonal direction. The reverse situation allows coupling some orthogonal light in the glass to have a total attenuated internal reflection.

[0082] The electronic device further comprises one or more light sources 41, 42 for providing a light beam 31, 51 directed towards the lower surface of the glass 32 opposite to the upper measurement surface on which the finger D (whose position is to be determined) is placed. As soon as the finger D touches the measurement surface, there is a region of evanescent wave coupling of the light beam in the direction of the finger. Thereafter, the light wave 34 is reflected between the lower and upper surfaces of the glass 32 to be picked up by a photodetector 36 (which may be a photodiode) at one end or edge of the glass. One or two light shields 35 fixed on the lower and / or upper surface of the glass 32 are provided above and below the photodiode 36.

[0083] according to Fig. 9 In a first embodiment of the invention, several light beams 31 are generated by one or more first light sources (not shown). These light beams 31 are directed perpendicularly to the lower surface and perpendicularly to the upper surface. Depending on the position of the finger D on the measurement surface, there is an attenuation of the signal picked up by the photodiode, which depends on the distance between the finger D and the photodiode 36. Figure 1 and Figure 2 All position learning operations explained are particularly applicable to this optical variant of the electronic device.

[0084] according to Fig.10 In a second embodiment, two light emitting diodes 41, 42 are prepared, which may be infrared diodes. The two infrared sources are modulated and used to illuminate the glass 32 with a given power gradient. The first infrared diode 41 provides the first light radiation 31 and is inclined at a defined angle relative to the vertical to the surface, and the same applies to the second infrared diode 42 providing the second light radiation 51. The first beam 31'OOK1 arriving in the direction of the finger D is tilted differently from the second beam 51'OOK2. Moving the finger along the axis X will cause the first signal to be coupled more or less relative to the second signal at the photodiode 36 for detection. Therefore, the distance-dependent optical power ratio OOK1 / OOK2 is determined.

[0085] Finally, according to Fig.11 In a third embodiment, two modulated infrared sources are used to illuminate the glass 32 with a given power gradient according to a first light beam 31 OOK1 and a second light beam 51 OOK2. Moving the finger D on the axis X will more or less couple the first signal relative to the second signal at the photodiode for detection. In particular, the illumination percentage or power gradient (current ratio OOK1 / OOK2) of each infrared diode is indicated for the first infrared diode 41. Thus, the optical power ratio OOK1 / OOK2 is determined depending on the distance.

[0086] Each electronic device for determining at least one position of an object on a measuring surface by means of an optical signal transmission propagation medium comprises a measuring circuit which receives the output signal from the photodiode 36 and controls the light emitting diode(s) 41, 42. For these three embodiments, the same initial stage of learning the different positions of the object D on the measuring surface is performed, as has been previously described with reference to Figure 1 and Figure 2 Just as described.

[0087] As indicated above, if the electronic device 1 is installed in an electronic or electromechanical meter, the determination of the position of, for example, a finger placed on the measuring surface of the electronic device 1 can be used to control functions. It is also possible to consider using the electronic device for recognizing a signature made by an object (stylus) or a human finger, or for recognizing characters drawn on the measuring surface and found in a character library. As such, there must also be a learning phase for signature or character recognition on the measuring surface, performed by a computer machine connected to the electronic device, to determine the positions X and Y and also the time (important parameters for the signature). All these data are transmitted and stored in the electronic device 1. This allows movements to be performed on the measuring surface with a stylus or a finger within a determined time window, so that the electronic device 1 easily determines the signature or any drawn character once it has been configured.

[0088] According to the description that has just been given, a person skilled in the art can design several variant embodiments of the method for detecting the presence of at least one object on a measuring surface of an electronic device and / or determining the position of at least one object on a measuring surface of an electronic device without departing from the scope of the invention as defined by the claims. The propagation medium can also be configured using a resistor array on the measuring surface.

Claims

1. A method for determining the position of an object on or near a measuring surface of an electronic device, the electronic device comprising an oscillating signal propagation medium and a measuring circuit, the method comprising: providing one or more oscillating signals at one or more input points that are distinct and spaced apart from a first portion of the propagation medium in a detection region of the measurement surface, receiving one or more oscillating signals having passed through the propagation medium in one or more different output points spaced apart by a second portion of the propagation medium in the detection area of ​​the measurement surface, the propagation medium defining a transfer function for the oscillating signals, measuring in a measuring circuit the coupling or attenuation of one or more oscillating signals through a propagation medium caused by the presence of an object placed on or near a measuring surface; as well as The position of the object is determined by applying the results of the measurements to a neural network trained using training data.

2. The method of claim 1 , wherein the neural network is trained during an initial learning phase in which different positions of objects on or near the measuring surface are learned by a learning machine that receives various measurements relating to different positions of objects on or near the measuring surface, wherein the determination of the exact position in X and Y of the object on or near the measuring surface is performed by a learning machine after an initial learning phase to define the positions in X and Y of different positions of the object on or near the measuring surface depending on the oscillating signal measured in the measuring circuit, and Different values ​​X and Y for different positions on the measuring surface are transmitted and stored in a memory of the measuring circuit of the electronic device to parameterize and configure the electronic device to facilitate its subsequent determination of the position of any object placed on or near the measuring surface.

3. A method according to claim 2, wherein the learning machine is provided external to the electronic device, and wherein the electronic device communicates various measurements relating to different positions of the object on or near the measurement surface to the learning machine including the neural network.

4. A method according to claim 2, wherein various measurements relating to different positions of the object on or near the measuring surface are provided to a neural network in the measuring circuit, Therein the neural network is parameterized using synaptic weights determined by a learning machine used during an initial learning phase, and wherein any position or inclination of an object on a measurement surface is calculated with low power.

5. A method according to claim 2, wherein in a subsequent learning phase, the learning machine is provided in a mobile phone having a program for guiding the user regarding the different patterns to be performed on the measuring surface, Wherein the mobile phone is configured to perform wireless communication of data signals with the electronic device, a plurality of successively digitized measurement signals of a plurality of positions of an object on a measuring surface are transmitted to the mobile phone via near field communication for use in determining position values ​​in X and Y which are transmitted by the mobile phone to the electronic device to be configured.

6. The method according to claim 2, wherein in an initial learning phase any movement of the object is determined in the measurement signal transmitted by the electronic device, wherein after this initial learning phase, the learning machine transmits to the electronic device all configuration parameters for recognizing the signature or drawn character, said configuration parameters being the synaptic weights associated with different values ​​in X and Y for different positions and the time component, and The object is one of a stylus or a human finger on the measuring surface for the purpose of performing a signature within a defined time window or for recognizing characters drawn on the measuring surface.

7. The method according to claim 1, wherein the oscillating excitation signal is provided to an input point of a first portion of the propagation medium in the detection area of ​​the measurement surface, wherein the several output signals are received at different output points spaced apart from the second portion of the propagation medium in the detection region of the measuring surface, and The measuring circuit digitizes all output signals to determine the position of the object on the measuring surface or to be transmitted to a learning machine in an initial learning phase.

8. The method according to claim 1, wherein the electronic device comprises an array of capacitive sensor electrodes as a propagation medium, the array comprising a number of electrodes arranged close to each other in a matrix form, a major part of the capacitive electrodes being floating electrodes which are not connected to a measurement circuit or adjacent electrodes by conductive tracks, while some electrodes at the periphery of the propagation medium are connected to the measurement circuit by conductive tracks, wherein each of the at least two oscillating signals at the input is provided to a respective input electrode at a periphery of the first portion of the electrode array, the two electrodes receiving the oscillating input signal being spaced apart from each other, and Wherein the output measurement signal is received by an output electrode at the periphery of the second part of the electrode array, the input electrodes and the output electrodes are arranged to cover the entire detection area of ​​the measurement surface to determine the position of an object on the measurement surface.

9. The method of claim 8, wherein a first analog broadband oscillating signal is provided to a first input electrode and a second analog quadrature oscillating signal is provided to a second electrode remote from the first electrode on the first portion of the propagation medium.

10. A method according to claim 9, wherein the broadband signal is projected in the measurement circuit to give a transfer function fct(A2 / A1), wherein A1 is the attenuation of the first excitation signal at the measurement point, and A2 is the attenuation of the second quadrature signal at the measurement point, and wherein the influence of an object placed in the detection area is determined between a first electrode receiving a first excitation signal and an output electrode receiving an output measurement signal, where the quadrature signals are also projected to give the transfer function fct(A1 / A2), and Therein, the two functions fct(A2 / A1) and fct(A1 / A2) are subtracted to give an output digital measurement signal Fct(A1, A2) of the measurement circuit, wherein the output digital measurement signal Fct(A1, A2) is on N bits.

11. An electronic device comprising: a measuring circuit connected to the propagation medium; a memory storing one or more instructions; as well as A processor configured to execute one or more instructions for: providing one or more oscillating signals at one or more input points that are distinct and spaced apart from a first portion of the propagation medium in a detection region of a measurement surface of the electronic device; receiving one or more oscillating signals having passed through the propagation medium in one or more different output points spaced apart by a second portion of the propagation medium in the detection region of the measurement surface, the propagation medium defining a transfer function of the oscillating signals; Measuring the coupling or attenuation of one or more oscillating signals through a propagation medium caused by the presence of an object placed on or near a measurement surface; as well as The position of the object is determined by applying the results of the measurements to a neural network trained using training data. 12 . The electronic device of claim 11 , wherein the oscillation signal comprises one of an electrical signal, an optical signal, an ultrasonic signal, or an electromagnetic signal.

13. The electronic device of claim 11, wherein the oscillating signal comprises a signal created by mixing an ultrasonic pressure wave and a local electrical or optical feature.

14. The electronic device according to claim 11, wherein the electronic device comprises a propagation medium for propagating the optical signal, The propagation medium is the glass of the portable instrument. wherein, in order to determine the position of the object, light beams from one or more different light sources are directed in the direction of an evanescent wave coupling region below the position of the object at the lower surface of the glass and at the upper surface of the glass, and The light waves are reflected between the lower and upper surfaces of the glass to be picked up by photodetectors at the edge of the glass.

15. The electronic device according to claim 14, wherein at least two light emitting diodes are prepared, the at least two light emitting diodes are modulated and used to illuminate the glass with a given power gradient, wherein the first light emitting diode provides a first light beam tilted at an angle defined relative to a perpendicular to the surface, and the second light emitting diode provides a second light beam tilted differently than the first light beam, and The electronic device determines from the output of the photodetector a light power ratio which is dependent on the distance between the position of the object on the measurement surface and the photodetector.

16. The electronic device according to claim 14, wherein at least two light emitting diodes are prepared, the at least two light emitting diodes are modulated and used to illuminate the glass with a given reverse power gradient, wherein a first light beam is generated perpendicular to the glass by a first light emitting diode, and a second light beam is generated perpendicular to the glass by a second light emitting diode, and The electronic device determines from the output of the photodetector a light power ratio which is dependent on the distance between the position of the object on the measurement surface and the photodetector.

17. The electronic device according to claim 11, wherein the propagation medium is an array of capacitive sensor electrodes, the array comprising a number of electrodes arranged close to each other in a matrix form, a major part of the capacitive electrodes are floating electrodes which are not connected to a measurement circuit or adjacent electrodes by conductive tracks, while some electrodes at the periphery of the propagation medium are connected to the measurement circuit by conductive tracks, wherein two input electrodes at the periphery of the first portion of the electrode array are each adapted to receive one of the two oscillating signals, respectively, the two input electrodes being spaced apart from each other, and Wherein the output electrodes at the periphery of the second part of the electrode array are adapted to receive the output measurement signal, the input electrodes and the output electrodes are arranged to cover the entire detection area of ​​the measurement surface to determine the position of an object on the measurement surface.

18. The electronic device of claim 17, wherein the array of electrodes comprises electrodes having a comb-like shape structure to partially interlock with each adjacent electrode, wherein each electrode comprises an X-shaped base and extending from the X-shaped base and sized to form four small square teeth from each branch of the base, and Four of the small square teeth and the base form each square-shaped electrode, thereby allowing each small square tooth of each electrode to interlock with another small square tooth of an adjacent electrode.

19. The electronic device of claim 17, wherein the array of electrodes comprises a set of square shaped electrodes in a matrix form with reduced spaces between each electrode.

20. The electronic device of claim 17, wherein the array of electrodes comprises a set of electrodes having a hexagonal shape and arranged as a honeycomb with a reduced space between each electrode.

21. The electronic device of claim 17, wherein the array of electrodes is arranged to receive a first excitation signal through a first electrode and a second orthogonal signal through a second electrode spaced apart from the first electrode, and to provide a measurement output signal to an output electrode based on a change in the oscillation signal depending on an object placed on the measurement surface, wherein the measuring and excitation means of the measuring circuit comprises an analog to digital converter for converting the output signal into a digital signal, wherein the measuring circuit comprises a complex projection operator, the complex projection operator receiving a digital signal from a unit of an excitation signal prototype which becomes a first excitation signal of the digital signal to project the output signal converted into the digital signal, wherein the measuring and excitation means comprises a phase accumulator Cplx receiving the output signal from the complex projection operator and which takes into account the real and imaginary parts of the digitized projection signal, and Therein the phase accumulator Cplx provides an N-bit digital signal of output measurement, which is intended to be transmitted to a learning machine for each position measurement during an initial learning phase of the electronic device.

22. The electronic device according to claim 21, wherein the accumulator is connected to a logic control unit, the logic control unit comprising a generator of signals in the digital domain to control a unit of an excitation signal prototype of a first excitation signal that becomes the digital signal and a unit of an excitation signal prototype of a second excitation signal orthogonal to the first signal that becomes the digital signal, wherein the output of the unit of the excitation signal prototype of the first excitation signal is converted in a first digital to analog converter to provide a first oscillating excitation signal to the electrode array, and The output of the unit of the excitation signal prototype of the second excitation signal is converted in a second digital to analog converter to provide a second oscillating signal orthogonal to the electrode array.

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