Multitouch tactile device with multi frequency and barycentric capacitive detection

Touchscreen device with projected capacitive detection comprising a matrix touchpad comprising a plurality of conducting rows and of conducting columns, the said pad being linked to electronic control means generating, for each conducting row and for each column, emission voltages and electronic means of reception and analysis of the reception voltages arising from each conducting row and from each column,

• the electronic control means generating, for each conducting row arid for each column, a first periodic emission voltage emitted at a first frequency termed the working frequency and a second periodic emission voltage emitted at a second frequency termed the discrimination frequency, different from the first frequency:
• in the absence of any press, the value of the working frequency being low enough to cause very low variations of the reception voltages at this working frequency and the value of the discrimination frequency being high enough to cause appreciable variations of the reception voltages dependent on the rows and columns at this discrimination frequency;
• the electronic reception and analysis means being arranged so as to determine, for each row and for each column:
• the value of a first reception voltage at the working frequency and the value of a second reception voltage at the discrimination frequency;
• if, as a function of predetermined values, the values of the two reception voltages are representative of two simultaneous presses on the touchpad and the location of these two presses on the two rows and on the two columns concerned;
• wherein, in the case of two simultaneous presses, the first press situated at a first crossover of a first row and of a first column and the second press situated at a second crossover of a second row and of a second column, location of the two presses is performed by means:
• of first analysis means making it possible to pinpoint the “troughs” of the reception voltages for the first frequency and the “troughs” of the reception voltages for the second frequency corresponding to the voltage variations of the two presses;
• of second analysis means making it possible to calculate the barycentres of the voltage “troughs”;
• of third analysis means making it possible to determine, on the basis of the knowledge of the barycentres, the first row and the first column corresponding to the first press and the second row and the second column corresponding to the second press.