| 主权项 |
1. A touchscreen device with projected capacitive detection comprising a touch-sensitive matrix panel comprising a plurality of conductive rows and conductive columns, said panel being connected to electronic control means generating, for each conductive row and column, transmission voltages and electronic means of reception and analysis of the reception voltages originating from each conductive row and column,
the electronic control means generating, for each conductive row and column, a first periodic transmission voltage transmitted at a first frequency denoted as the working frequency and a second periodic transmission voltage transmitted at a second frequency denoted as the discrimination frequency, different from the first frequency: in the absence of any press, the value of the working frequency being sufficiently low to cause very small variations in the reception voltages at this working frequency and the value of the discrimination frequency being sufficiently high to cause significant variations in the reception voltages according to the rows and columns at this discrimination frequency; the 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; wherein said electronic analysis means comprise: a table of stored values of the reception voltages at the working frequency of each row and of each column in the absence of any press; comparison means establishing, for each row and for each column, the differences between the measured values of the reception voltages and the stored values of the reception voltages so as to determine whether the measured differences are representative of a cut row or column and/or a press on an intact row or column; first analysis means arranged so that:
if the reception voltages of the set of rows display a ‘hollow’ representative of a press and the reception voltages of the set of columns do not display a ‘hollow’ representative of a press, a column is diagnosed as cut, the positions of said faulty column and of the press being determined by measuring the differences in reception voltage taken at the working frequency and at the discrimination frequency of the rows located at said press;if the reception voltages of the set of columns display a ‘hollow’ representative of a press and the reception voltages of the set of rows do not display a ‘hollow’ representative of a press, a row is diagnosed as cut, the positions of said faulty row and of the press being determined by measuring the differences in reception voltage taken at the working frequency and at the discrimination frequency of the columns located at said press. |
