Abstract:
A data acquisition method to acquire data from a multicontact matrix tactile sensor having a matrix array of a cells, includes scanning the cells of the matrix array sequentially, and measuring an electrical characteristic of a cell, which represents a weight of the cell. The method also includes comparing the weight with a predetermined significant weight value interval, storing cell data associated with the cell, where the cell data includes the weight and coordinates of the cell in the matrix array, after the weight is determined to lie within the predetermined significant weight value interval. The method also verifies an existence of a data record associated with neighboring cells in a neighboring zone of the cell, and updates the data record associated with the neighboring cells by storing in the data record data associated with the cell, after the existence of the data record is confirmed.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit under 35 U.S.C. §119 from French Application No. 11 50868, filed Feb. 3, 2011, the entire content of which is incorporated herein by reference. 
     FIELD OF THE INVENTION 
     The present invention concerns a method of acquisition of data from a multicontact matrix tactile sensor. 
     It also concerns such a multicontact matrix tactile sensor and a touch screen comprising, in juxtaposed manner, a display screen and a multicontact matrix tactile sensor. 
     In general, the present invention concerns the acquisition of representative data from one or more contacts or points of pressure exerted on the surface of a tactile sensor. 
     BRIEF DESCRIPTION OF THE BACKGROUND ART 
     A matrix sensor is made up of an assembly of cells disposed in row and in column. In its most common form of operation, these cells are sequentially scanned in order to measure the presence of points of contact or points of pressure. Such multicontact tactile sensors and their analysis method are described, for example, in documents EP 1 719 047 or EP 2 142 980. In document EP 2 142 980, the cells are made up of a material acting as a diode. 
     Likewise, the present invention concerns tactile sensors using a matrix of active cells, such as those of TFT type (Thin Film Transistor), of photodiode type, which can be directly integrated in the matrix of an LCD screen (Liquid Crystal Display), or even of piezo-electric type. 
     In document EP 1 719 047, the matrix tactile sensor is made up of a matrix array of strip conductors disposed along rows and columns, cells being thus defined at each intersection of the rows and the columns of the matrix array. 
     The acquisition of data is done by sequentially scanning each cell of the matrix array, that is, by successively energizing each row of the matrix array and measuring, for each row energized, and at each column successively, an electrical characteristic representative of an impedance level. 
     The set of these electrical characteristics representative of a level of impedance of each cell is then memorized. 
     By virtue of this sequential scanning of the cells, it is possible to detect simultaneously several zones of contact on the tactile sensor during each scanning phase. 
     The data measured, and especially the level of impedance of each cell, are recorded. 
     Due to the recording of the set of data acquired in each scanning phase, it is necessary to have an electronic memory of large size, thus increasing the manufacturing cost of the tactile sensor. 
     Furthermore, in the context of a tactile sensor having great sensitivity and possibly containing several thousand cells, depending on the size of its tactile surface, the set of data acquired for each cell is then analyzed to determine surrounding zones, that is, encompassing several neighboring cells in the matrix array and thus corresponding to a single contact or a point of pressure on the tactile surface of the sensor. 
     This step of determination of surrounding zones thus requires an analysis of the matrix image of the sensor, obtained during the sequential scanning phase, and it induces a latency period in the response of the sensor. 
     This step of analysis of the set of data stored in memory takes longer to implement as the matrix image stored in memory is more complex. When this analysis step is realized in parallel with a scanning phase, it is necessary to provide a buffer memory size that is sufficient to record at least two matrix images of the sensor at the same time. 
     BRIEF SUMMARY OF THE INVENTION 
     The purpose of the present invention is to solve the aforesaid drawbacks and to propose a method of acquisition of data from a multicontact matrix tactile sensor requiring only a limited electronic memory size, and reducing the latency period needed for analysis of the matrix image, thus improving the performance of the system and the ease of use. 
     For this, the present invention concerns a method of acquisition of data from a multicontact matrix tactile sensor, comprising a matrix array of cells, involving the following steps:
         sequential scanning of the cells of the matrix array;   measuring of an electrical characteristic at each cell representative of a weight of each cell.       

     According to the invention, this method of acquisition of data further comprises the following steps, for each cell:
         comparing said weight with one or more predetermined significant weight values;   recording the data associated with said cell, comprising at least said weight and the coordinates of said cell in the matrix array when the weight belongs to an interval of significant values;   verifying the existence of a record of data associated with at least one of said neighboring cells contained in a neighboring zone associated with said cell; and   updating an existing surrounding zone by recording in said existing surrounding zone data associated with said cell if data associated with at least one neighboring cell belonging to said existing surrounding zone have been recorded.       

     Depending on the type of matrix tactile sensor used, the weight associated with each cell may be different. 
     In general, the weight corresponds to a factor characterizing how much the cell is touched in the data acquisition process. 
     In particular, this weight can be calculated according to a measurement of impedance directly accessible from the measurement of an electrical characteristic at each cell. 
     By comparing this weight with one or more predetermined significant weight values, it is thus possible to verify if the weight is higher than a predetermined significant value, or else lower than a predetermined significant value, or finally within one or more intervals of predetermined significant values. 
     In general, the comparison step lets one verify if the weight of each cell is significant, that is, if its value really corresponds to a contact at the cell of the matrix tactile sensor. 
     It will be noted that the predetermined significant values used during the comparison step can vary according to the cell measured or even in time according to the conditions of use of the matrix tactile sensor. 
     Thus, one makes a selective recording of the data measured for each cell during the steps of sequential scanning and measurement of an electrical characteristic representative of the weight associated with this cell. 
     Thus, only the data associated with cells corresponding to a point of contact on the matrix tactile sensor are recorded. 
     Furthermore, the gradual updating of each existing surrounding zone makes it possible to obtain, during the actual data acquisition, the location of the surrounding zones made up of neighboring cells having a significant weight. 
     The method of acquisition of data according to the invention thus avoids the needless recording of data associated with each cell and eliminates the successive analysis phases of the recorded data in order to determine the surrounding zones, the latter being updated in the course of the data acquisition step. 
     In practice, the acquisition method further comprises a step of creating a new surrounding zone by recording of data of the cell in the new surrounding zone if no datum associated with a neighboring cell contained in the neighboring zone associated with the cell has been recorded. 
     The creation of the surrounding zones and their updating are thus realized simultaneously in the course of the acquisition of data during the sequential scanning of the cells of the matrix array. 
     According to one advantageous embodiment of the invention, the neighboring zone associated with the cell is made up of a parametrizable number of neighboring cells of the cell in the matrix array. 
     Thus, the step of verification of the existence of a recording of data associated with a neighboring cell is limited to a portion of the matrix array, in the neighborhood of the cell in question. 
     This portion of the matrix array can thus correspond to a surface of size corresponding basically to the size of a zone of contact on the tactile surface of the sensor, for example, by a finger of the user. 
     In practice, the neighboring zone of a cell is made up of neighboring cells scanned prior to said cell during the sequential scanning step. 
     This characteristic further makes it possible to speed up the step of verification, since it is limited to the neighboring cells already scanned, thus disregarding the neighboring cells for which no data record can exist, since they have not yet been subjected to the sequential scanning and measurement of an electrical characteristic. 
     According to another aspect of the invention, it concerns a device for acquisition of data from a multicontact matrix tactile sensor, comprising a matrix array of cells, comprising:
         means of sequential scanning of the cells of the matrix array;   means of measuring an electrical characteristic at each cell representative of a weight of each cell.       

     According to the invention, this data acquisition device further comprises:
         means of comparison of said weight of each cell with one or more predetermined significant weight values;   means of recording the data associated with the cell, comprising at least the weight and the coordinates of the cell in the matrix array when the weight belongs to an interval of significant values;   means of verification of the existence of a record of data associated with at least one of the neighboring cells contained within a neighboring zone associated with the cell; and   means of updating an existing surrounding zone by recording in the existing surrounding zone data associated with the cell if data associated with at least one neighboring cell belonging to the existing surrounding zone have been recorded.       

     The present invention also concerns a multicontact matrix tactile sensor, comprising a matrix array of strip conductors made up of rows and columns, cells being defined at the intersections of the rows and columns, and means of acquisition of data able to implement the method of acquisition according to the invention. 
     Finally, it concerns a touch screen, comprising a display screen juxtaposed with a multicontact matrix tactile sensor as previously defined. 
     This data device, this multicontact matrix tactile sensor and this touch screen have characteristics and advantages similar to those described previously in connection with the method of acquisition of data according to the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
       Other features and advantages of the invention also will become apparent in the following description. In the attached drawings, given as nonlimiting examples: 
         FIG. 1  is a schematic perspective view of a touch screen according to one embodiment of the invention ; 
         FIG. 2  is a top view showing schematically the arrangement of the rows and columns of strip conductors of a multicontact matrix tactile sensor according to one embodiment; 
         FIG. 3  is a functional diagram detailing the steps of the process of acquisition of data according to one embodiment of the invention; 
         FIG. 4  is a view illustrating neighboring cells contained within a neighboring zone of a matrix array cell; 
         FIG. 5  is a diagram illustrating the step of verification of the existence of a record of data associated with a neighboring cell; 
         FIG. 6  is a diagram illustrating the weight value measured when two points of pressure are present close to one another on a tactile sensor of capacitive type; 
         FIGS. 7 and 8  are diagrams illustrating a step of supplemental analysis of the process of data acquisition illustrated in  FIG. 3 , in the context of an implementation on a tactile sensor of capacitive type; 
         FIG. 9  is a schematic view illustrating surrounding zones made up of a set of cells of the matrix array; and 
         FIG. 10  is a diagram illustrating the step of calculation of the position of a center of gravity of a surrounding zone so as to determine a cursor. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     First of all, we shall describe a touch screen  10  according to one embodiment of the invention, making reference to  FIG. 1 . 
     This touch screen  10  comprises a multicontact matrix tactile sensor  11  juxtaposed with a display screen  12 . 
     In this embodiment, and in nonlimiting manner, the multicontact matrix tactile sensor  11  is disposed above the display screen  12 . 
     In particular, this tactile sensor  11  should be transparent under these conditions, to enable the display of data appearing on the underlying display screen  12 . 
     The touch screen  10  also comprises a capture interface  13 , a main processor  14  and a graphics processor  15 . 
     The capture interface  13  in particular makes it possible to acquire data measured at the multicontact tactile sensor  11 . 
     This capture interface  13  contains the acquisition and analysis circuits necessary for the acquisition of data, which then can be transmitted to the main processor  14  for processing, then implementation of various functions of the touch screen  10 . 
     Only the mode of acquisition of data representative of key strokes of the tactile sensor  11  will be explained below, the use of the key strokes by the main processor  14  not being described here. 
     One will refer advantageously to the exemplary embodiments described in the document EP  1   719   047  regarding the different applications and uses of such a touch screen  10 . 
     There is illustrated schematically in  FIG. 2  an example of a matrix tactile sensor  11  as implemented in  FIG. 1 . 
     This matrix tactile sensor  11  comprises a matrix array  21 ,  22  of strip conductors, the two arrays  21 ,  22  being disposed in nonparallel manner. 
     These arrays  21 ,  22  of strip conductors thus form rows  23  and columns  24 , cells  25  being defined at the intersections of these rows  23  and these columns  24 . 
     Of course, in the entire following description, the notion of rows and columns is interchangeable, depending on the orientation of the matrix tactile sensor  11 . 
     The arrays  21 ,  22  of strip conductors are made, for example, of a conductive material, preferably translucid, for example by means of transparent metal oxides such as ITO (Indium Tin Oxide), solutions based on metallic nanoparticles, or else miniature conductor threads. 
     The array of lower strip conductors (for example, the rows  23 ) can be positioned on a layer of glass and the array of upper strip conductors (for example, the columns  24 ) can be positioned beneath a layer of polyethylene terephthalate (PET). 
     A layer of air separates the two arrays  21 ,  22  of strip conductors such that the rows  23  and the columns  24  are not in electrical contact. 
     When pressure is applied to the outer surface of the matrix tactile sensor  11 , the impedance at each cell  25  corresponding to a touching of the surface of the matrix tactile sensor  11  is modified. 
     The matrix tactile sensor  11  can be, for example, a sensor of resistive type: upon a touching or a pressing on the outer surface of the matrix tactile sensor  11 , the strip conductors of the matrix arrays  21 ,  22  are placed in contact at one or more cells  25  of the matrix array, such that a contact resistance is created at these cells  25  and it can be detected as explained further below. 
     Alternatively, the matrix tactile sensor  11  can be a sensor of projected capacitive type: the position of a finger opposite a cell  25  placed at the intersection of a row and a column modifies the impedance in the area of this intersection, which can also be detected as explained further below. 
     Of course, the exemplary embodiments given above for the matrix tactile sensor  11  are purely illustrative, and the method of acquisition of data described below can apply to all types of tactile sensors defining a matrix array of cells. 
     The set of means described above in regard to  FIG. 1 , and especially the capture interface  13  and the microprocessor  14 , are adapted to integrate a data acquisition device to implement the data acquisition method that will be described below. 
     In this regard, the capture interface  13  and the microprocessor  14  integrate in particular means of sequential scanning of the tactile sensor  11  and measurement of an electrical characteristic. 
     We shall now describe the method of data acquisition according to one embodiment of the invention, making reference to  FIG. 3 . 
     In principle, the method of data acquisition in this embodiment consists in sequentially scanning the different cells  25  of the matrix array to detect the different zones of contact in the area of the matrix tactile sensor during a scanning phase. 
     The method of acquisition involves, first of all, an initialization step S 31  carried out at the start of each new scanning phase in order to reinitialize all of the parameters described hereafter, making it possible to detect the different zones of contact on the matrix tactile sensor  11 . 
     A step of sequential scanning of the cells  25  of the matrix tactile sensor  11  is then performed in order to measure, at each cell  25 , an electrical characteristic. 
     In principle, this sequential scanning step consists in injecting an electrical signal sequentially in an array of strip conductors of the matrix array, and for example the rows  23 , and measuring an electrical characteristic on the other array of strip conductors, and for example on the columns  24  in succession. 
     In the case of a resistive sensor, when a pressure is exerted on the outer surface of the matrix tactile sensor, the rows  23  and the columns  24  come into contact at one or more cells  25  situated at the crossing of the rows and columns, such that the measurement of an electrical characteristic on the terminals of each column, for example a voltage, is representative of a modification of the resistance of the circuit at each cell  25  corresponding to a point of contact. 
     Similarly, in a sensor of capacitive type, the measurement of an electrical characteristic on the terminals of each column makes it possible to detect the variation in impedance, which is here a level of capacitance, representative of a touch at one or more cells of the matrix array. 
     The measurement of an electrical characteristic thus makes it possible to obtain a value representative of a weight associated with each cell. 
     This weight is here a function of the level of impedance (resistance, capacitance) at the cell, which is modified by the presence of a touch opposite the cell. 
     The steps of sequential scanning and measurement of an electrical characteristic are detailed below making reference to  FIG. 3 . 
     In this exemplary embodiment, one considers a matrix array made up of N columns C and M rows R. Such a matrix array thus contains M×N cells. 
     An initialization step S 32  lets one take into account the first column C=0. 
     In a test step S 33 , one checks to see if the current column C has the value N. 
     If so, the step of sequential scanning of the cells  25  is terminated. 
     If not, one performs the necessary adjustments to obtain a correct measurement at the current column C via a multiplexer. For example, one places all the columns other than the current column C at high impedance Z to prevent the flow of current in these other columns. 
     These adjustments are done during a step S 34 . 
     An initialization step S 35  then allows one to consider the first row R=0. 
     One checks in a test step S 36  whether this current row R has the value M. 
     If not, a step of adjustment S 37  of the rows is done via a multiplexer. For example, a selective energization is carried out, in which all the rows other than the current row R are placed at ground via a pull-down resistor. 
     Thus, only one electrical signal is injected into the current row R. 
     A measurement step S 38  is then carried out to measure an electrical characteristic representative of a weight connected to the level of impedance I RC  associated with the cell CELL corresponding to the intersection of the current column C and the current row R. 
     In this embodiment, the electrical characteristic measured is, for example, a voltage. An ADC (acronym for the English term Analog Digital Converter) circuit lets the analog voltage value be converted into a digital signal, which can then be used during the comparison step S 39 . 
     In the context of a capacitive sensor, one would use a CDC (acronym for the English term Capacitance to Digital Converter) circuit. 
     The comparison step S 39  is then carried out to compare the measured weight value with one or more significant weight values corresponding to a real touch on the current cell. 
     Here, in the context of a measurement of a voltage directly representative of a level of impedance (here, a resistance), the comparison step S 39  consists in comparing the level of impedance measured I RC  with a predetermined impedance threshold I T.    
     In the context of a resistive sensor, this impedance threshold value I T  is determined according to the noise level inherent in the electronic system. 
     Thus, the use of an impedance threshold value I T  makes it possible to eliminate the measurements of stray electrical characteristics associated with the electronic system, and not in reality representing a point of contact on the matrix tactile sensor  11 . 
     It will be noted that this predetermined impedance threshold value I T  can possibly be changed in the matrix tactile sensor  11  to adapt to different electromagnetic environments. 
     Thus, if at the end of the comparison step S 39  the weight is considered to be not significant, that is, if the impedance level measured I RC  is less than the predetermined impedance threshold I T , no datum is memorized for the cell R, C and an incrementation step S 41  is carried out in order to consider the next row R=R+1. 
     Steps S 36  and following are then reiterated on the next row. 
     If during the test step S 36  the current row value R has reached the limit value M, that is, all the rows R have been scanned, an incrementation step S 42  is carried out to consider the next column C=C+1. 
     All of the steps S 33  and following are then reiterated. 
     Of course, during the comparison step S 39  to determine whether the weight value associated with each cell is considered to be significant, other types of comparison can be carried out. 
     In particular, in the case of a tactile sensor of capacitive type, the weight measured is compared to several predetermined significant values making it possible to determine if the measured weight value is contained within a range of significant values. 
     Now making reference to  FIGS. 6 and 7 , we shall describe the rest of the process of data acquisition in an embodiment that implements a tactile sensor of capacitive type. 
     If at the end of the comparison step S 39  the weight is considered to be significant, that is, in this example, if the impedance level I RC  is greater than the impedance threshold I T , a recording step S 43  is carried out. 
     During the recording step S 43 , the data associated with the current cell CELL are recorded, in particular, the coordinates of the cell in the matrix array (CELL_X, CELL_Y) as well as the impedance level I RC  or weight measured. This impedance level I RC  thus characterizes the touch at the cell CELL and here is also known as the weight (WEIGHT) of the cell CELL. 
     It will thus be noted that only the data corresponding to cells CELL having a significant weight or impedance level are thus recorded during the recording step S 43 . 
     A verification step S 44  is then carried out to check for the existence of a recording of data associated with one or more neighboring cells Cv contained within a neighboring zone of the current cell CELL. 
     This verification step S 44  will be described in greater detail in reference to  FIGS. 4 and 5 . 
     The neighboring zone associated with the current cell CELL is made up of neighboring cells Cv of the cell CELL in the matrix array. 
     As well illustrated in  FIG. 4 , the neighboring zone associated with the processed cell CELL is made up of a predetermined, possibly parametrizable number of neighboring cells Cv of this cell CELL in the matrix array. 
     In the exemplary embodiment illustrated in  FIG. 4 , the neighboring zone associated with the cell CELL is defined by the position of this cell, with coordinates CELL_X, CELL_Y in the matrix array of the tactile sensor  11 , and a set of neighboring cells Cv situated at a predetermined distance from the cell CELL in the matrix array. 
     In this example, the predetermined distance corresponds in the horizontal and vertical direction of the matrix array to a distance of three cells at most separating the neighboring cells Cv from the current cell CELL. 
     Thus, this neighboring zone corresponds basically to the neighboring cells Cv belonging to a circle having as its center the processed cell CELL and as its radius the distance separating the cell CELL from the neighboring cell of coordinates (CELL_X, CELL_Y−3) or the neighboring cell (CELL_X−3, CELL_Y). 
     We illustrate in  FIG. 4  a portion of the cells already scanned, considering a sequential scanning of the cells consisting in energizing each row sequentially from top to bottom of  FIG. 4  and measuring sequentially the columns from left to right of  FIG. 4 . 
     We illustrate in  FIG. 4  by white box the cells scanned for which no datum was recorded, the measured weight not being significant, and by black box the cells scanned whose data was recorded but not belonging to the neighboring zone, and by hatchmarks the cells already scanned whose data was recorded and belonging to the neighboring zone. 
     It will be noted that, preferably, the neighboring zone is made up solely of neighboring cells Cv scanned prior to the current cell CELL during the sequential scanning step. 
     Thus, during the verification step S 44 , this is carried out only on the neighboring cells Cv already scanned during the previously described sequential scanning step. 
     Preferably, the verification step S 44  for the existence of recorded data for cells Cv belonging to the neighboring zone is carried out in order of increasing distance, starting with cells the closest to the current cell CELL. 
     Thus, as illustrated in  FIG. 5 , we have numbered, as a nonlimiting example, a scanning order for the neighboring cells Cv during the step of verification S 44  of the existence of recorded data. 
     Here, one successively examines the data of the cells Cv 1  with coordinates (CELL_X, CELL_Y−1), Cv 2  with coordinates (CELL_X−1, CELL_Y), Cv 3  with coordinates (CELL_X−1, CELL_Y−1), Cv 4  with coordinates (CELL_X−1, CELL 13  Y+1), etc. 
     If at the end of the verification step S 44  a neighboring cell Cv of the neighboring zone has a recording of data associated with this neighboring cell Cv, a step of updating S 45  of an existing surrounding zone is carried out. 
     During this updating step, the data connected to the current cell CELL are recorded in the existing surrounding zone. 
     Thus, in the exemplary embodiment illustrated in  FIG. 4 , the existing surrounding zone after updating will contain all of the data pertaining to the black cells, the hatched cells, and the current cell CELL. 
     The data recorded for each cell belonging to the existing surrounding zone include, in particular, the coordinates CELL_X, CELL_Y of each cell CELL as well as the impedance level I R, C  or measured weight for this cell. 
     On the other hand, if in the verification step S 44  no data connected to a neighboring cell Cv contained in the neighboring zone associated with the current cell CELL has been recorded, then a creation step S 46  is carried out to create a new surrounding zone by recording of data of the current cell CELL in this new surrounding zone. 
     Thus, in the course of the measurement of a characteristic representative of an impedance level during the sequential scanning of the cells of the matrix array, one can create and update the surrounding zones, bringing together the relevant cells that have been recorded. 
     At the end of the steps of updating S 45  or creation S 46  of surrounding zones, the acquisition method reiterates all of the steps S 36  and following for the next row R=R+1. 
     The sequential scanning phase is terminated when all the rows R and columns C have been scanned. 
     During the carrying out of each scanning phase, the entire process illustrated in  FIG. 3  is reiterated, all of the parameters recorded for each surrounding zone being reinitialized in the initialization step S 31 , as previously described. 
     In order to have good responsiveness of the tactile sensor and follow in real time the changes in touch on the surface of the tactile sensor  11 , the sequential scanning phases are carried out at a frequency on the order of 100 times a second. 
     The above-described acquisition process, and especially steps S 43  and following, are supplemented by an additional analysis step in the context of an implementation on a tactile sensor whose output data are analog, that is, in Gaussian form (for example, for sensors of capacitive, inductive, or even pressure type). 
     As previously noted, in the case of a tactile sensor of capacitive type, for example, the measured weight is compared to several predetermined significant values. 
     As illustrated in  FIG. 6 , the measured weight in the context of a capacitive sensor is considered to be significant in the above-described comparison step S 39  when the measured weight value is included in a range of significant values Pmin, Pmax. 
     We have shown in  FIG. 6  an example of measured weight values when two contacts or points of pressure are applied to the tactile sensor of capacitive type, close to one another, and here close to one another in the direction X of the matrix grid of the tactile sensor. 
     In this case, two distinct points of pressure (symbolized by the references P 1  and P 2  in  FIG. 6 ) can be considered as belonging to the same surrounding zone in the implementation of the above-described acquisition method. 
     In fact, as illustrated in  FIG. 6 , the measured weight value for neighboring cells located between the points of pressure P 1  and P 2  can also be considered to be significant during the comparison step S 39 , since the weight values induced by the two points of pressure P 1  and P 2  are cumulative. 
     In fact, in sensors of capacitive type, the position of the point of pressure is deduced from the variation in charge built up on the lower conducting tracks, induced by the presence of the finger at the upper conducting tracks. 
     The measured signal corresponding to the charge distribution is a Gaussian signal whose apex (peak) corresponds to the position of the finger. 
     When two fingers are close and positioned at the upper conducting tracks, the two characteristic electrical signals are added and the measured values are the sum of the two Gaussians characteristic of each finger. 
     Thus, as illustrated in  FIG. 7 , during the registration step S 43  all of the cells CELL having a significant weight are registered, with the measured weight level represented here as nonlimiting examples for a numerical value between 1 and 11. 
     As illustrated in  FIG. 7 , in this embodiment, and solely as an example, a cell has a significant weight when the value of this weight is between 6 and 10, inclusively. 
     During the above-described verification step S 44 , the surrounding zone determined after updating will comprise all of the data pertaining at the same time to the cells having a significant weight (hatched cells and gray-shaded cells in  FIG. 7 ). 
     To prevent this confusion of two surrounding zones corresponding to different points of pressure on the tactile sensor, the verification step S 44  is supplemented by the implementing of a step of analysis of the values of the weight measured and registered in the registration step S 43  for a set of adjacent cells, including the current cell CELL of coordinates (CELL_X, CELL_Y). 
     In practice, as illustrated in  FIG. 8 , for each acquired cell CELL (cell A in  FIG. 8 ) of coordinates (X, Y), one analyzes the characteristics of the cells surrounding the neighboring cell B of coordinates (X−1, Y−1) in  FIG. 8 . 
     In practice, one compares the weight levels memorized for all of the cells adjacent to the neighboring cell B of coordinates (X−1, Y−1). 
     It is thus possible to detect, from the weight values, if the neighboring cell B of coordonates (X−1, Y−1) corresponds to a peak or a valley of the signal as illustrated in  FIG. 6 . 
     It will be noted that this step of supplemental analysis requires the presence of an additional buffer memory able to memorize, for the cells already scanned, the weight value measured for each cell belonging to the last three columns and last three rows with respect to the current cell CELL (or cell A in  FIG. 8 ). 
     When one detects that a neighboring cell B of coordinates (X−1, Y−1) corresponds to a peak with respect to the adjacent cells (weight value greater than or equal to that of the adjacent cells), it is possible to separate the existing surrounding zone into two distinct and adjacent surrounding zones illustrated schematically in  FIG. 7 , on the one hand by the cells with hatch marks and on the other hand by the gray-shaded cells. 
     Of course, this analysis process can also be implemented for a greater number of points of pressure close to each other on a tactile sensor of capacitive type, for example, three points. It will be noted that the comparison of the weights two by two between the neighboring cell B of coordinates (X−1, Y−1) and the adjacent cells can be implemented in a predetermined scanning order of the adjacent cells. 
     It will be further noted that, if the scanning is done row by row from left to right and column by column from top to bottom, one will have, for each neighboring cell B of coordinates (X−1, Y−1), weight values associated with the set of adjacent cells, that is, the set of cells included in the zone of coordinates X−2 and X on the abscissa and in the zone of coordinates Y−2 and Y on the ordinate, as illustrated in  FIG. 8 . 
     We illustrate in  FIG. 9  an example of a matrix array for which three surrounding zones ID 1 , ID 2 , ID 3  have been detected. 
     As previously mentioned, each surrounding zone is characterized in particular by the coordinates of each cell CELL making up this surrounding zone, as well as the impedance level or weight associated with each of these cells. 
     Furthermore, each surrounding zone is characterized, by way of nonlimiting example, by the height H and the width W of a rectangle circumscribing all of the cells CELL making up the surrounding zone. 
     Moreover, the position of the surrounding zone can also be defined by the coordinates of a specific point of this surrounding zone, and for example the coordinates X, Y of the upper left corner of the rectangle circumscribed around the cells making up the surrounding zone in the matrix array. 
     The surrounding zone is also characterized by the cumulative weight corresponding to the sum of the impedance levels or weights of each cell CELL belonging to the surrounding zone. 
     Of course, all of these parameters characterizing the surrounding zone (height H, width W, position of the upper left corner X, Y, cumulative weight, number of cells CELL belonging to the surrounding zone, as well as their coordinates CELL_X, CELL_Y and their impedance level or associated weight) are updated during each update step S 45  of the surrounding zone once a new cell has been added to this surrounding zone. 
     Thus, at the end of the data acquisition process, one has a set of surrounding zones and previously described parameters characterizing them. 
     In order to manage each zone of contact or pressure corresponding to each surrounding zone thus formed, one determines coordinates of a single point associated with this surrounding zone. 
     This determination of a single point in the matrix array of the tactile sensor  11  lets us associate a single point with each touch made on the tactile surface of the sensor  11 , so as to then follow the changes over time during each successive scanning phase. 
     One solution can be to consider as the single point the point having as its coordinates in the matrix array the geometrical center of the rectangle circumscribed around the set of cells making up the surrounding zone. 
     However, in order to take into account the distribution of the cells in the surrounding zone as well as the impedance values or weight associated with each of these cells, the point of contact is preferably determined by calculating a center of gravity of the surrounding zone, starting with coordinates CELL_X, CELL_Y of each cell CELL belonging to the surrounding zone, weighted by the impedance level I R, C  or weight connected with each cell. 
     To carry out this calculation of the center of gravity, one uses the cumulative weight value previously defined, corresponding to the sum of the impedance levels I R, C  or weights of each cell CELL belonging to the existing surrounding zone. 
     The calculation of the center of gravity is carried out classically by weighting the coordinates CELL_X, CELL_Y of each cell on the two axes X, Y by its impedance level or weight, in relation to the cumulative weight of the surrounding zone. 
     The unique position in the matrix sensor can then correspond in a touch screen to the position of a cursor on the display screen as illustrated in  FIG. 10 . This cursor making it possible to command a certain number of actions on this screen or on a peripheral computer device controlled by this touch screen. 
     By virtue of the above-described method, the detection of the surrounding zones is done in real time during the data acquisition and the sequential scanning of the sensor. 
     By virtue of this simultaneous processing of the data acquired, the required memory space is reduced. 
     In fact, the classical algorithms require the processing and the storage of all the data associated with the matrix arrays, and for example a memory space sufficient to store, in the previous example, M×N impedance values I R, C . 
     If, furthermore, one wishes a parallel data acquisition with the processing and analysis of this data, buffer memories need two to three times this memory space. 
     By virtue of the above-described method, by recording only the data pertaining to the surrounding zones, and in real time, and not all of the cells of the matrix array, the needed memory size can be greatly reduced. 
     Furthermore, the time of processing of the data furnished by the tactile sensor is reduced. 
     The responsiveness of the tactile sensor to the user&#39;s touch is thus augmented, affording a better comfort of use.