Proximity detection matrix display device

1. An electronic display device comprising:

means of detection of proximity of a conducting element situated in proximity to a display zone of the device;

a set of row electrodes and of column electrodes scanning the display zone;

means for generating an excitation of the row electrodes and of the column electrodes as a function of an image to be displayed on the display zone, comprising switches for applying the excitation successively to each of the row electrode and to each of the column electrodes;

means for applying a specific electrical signal distinct from the excitation successively to each of the row electrode and to each of the column electrodes through the switches,

means for continuously detecting modifications of the specific electrical signal which are induced by the presence of a conducting element in proximity to a region of the display zone,

and means for determining the position of said region as a function of said detected modifications.

2. The device as claimed in claim 1 , wherein the row electrodes and the column electrodes respectively form two distinct arrays, in that at least one array of electrodes is chosen for the proximity detection, and in that the means for determining the position of said region define this position as a function of the level of said modifications intervening on the chosen array.

3. The device as claimed in claim 1 , wherein the specific electrical signal is applied both to the rows and to the columns, and in that the means for determining the position of said region define this position as a function of at least one row and of at least one column for which said modifications overstep a threshold.

4. The device as claimed in claim 1 , wherein the electrical signal is applied simultaneously to at least one row electrode and to at least one column electrode and in that couplings between the row electrode and the column electrode are modified when the conducting element is in proximity to the crossover between the row electrode and the column electrode.

5. The device as claimed in claim 4 , wherein the specific electrical signal is applied to said set diagonally.

6. The device as claimed in claim 5 , wherein the electrical signal is applied to said set along two diagonals of the display zone.

7. The device as claimed in claim 1 , wherein the means for determining the position of said region take no account of the modifications unless they intervene on several neighboring electrodes.

8. The device as claimed in claim 1 , wherein the specific electrical signal is applied successively to various electrodes.

9. The device as claimed in claim 1 , wherein the electrodes are interdigitated.

10. The device as claimed in claim 1 , wherein the conducting element comprises a stylus.

11. The device as claimed in claim 1 , wherein the specific electrical signal has a frequency above 100 kilohertz.

12. The device as claimed in claim 1 , wherein it comprises means for driving the display, and in that these means comprise a multiplexer intended to apply an excitation voltage and the specific electrical signal to an electrode selected for the display.

13. The device as claimed in claim 12 , wherein the means for driving the display furthermore comprise means generating the specific electrical signal, an amplitude demodulator and an analog/digital converter, the amplitude demodulator receiving the specific electrical signal and providing the analog/digital converter with a signal representative of said modifications.

14. The device as claimed in claim 1 , wherein the specific electrical signal is superimposed on the excitation.

15. The device as claimed in claim 1 , wherein the specific electrical signal is applied to an electrode when the row and column electrodes are not selected for region detection.

16. The device as claimed in claim 1 , wherein the first electrode array is formed from the row electrodes and is situated between a plate and a layer and a second electrode array formed from the column electrodes is situated between another plate and the layer and wherein electrical excitation of the layer is achieved by applying a potential difference between an electrode of each array.

17. The device as claimed in claim 1 , wherein drivers are used for driving the display to apply the excitation voltage and the specification electrical signal to an electrode selected for the display.

18. The device as claimed in claim 1 , wherein the device comprises means for driving the display such that drivers are used to apply the excitation voltage and the specific electrical signal to an electrode selected for the display.