Capacitive detection device with arrangement of linking tracks, and method implementing such a device
A human-machine interface device is provided having a transparent detection zone and an access zone, and including a surface having electrodes made from a conductive transparent material in the detection zone, conductive connecting tracks arranged in the access zone and connected to the surface having electrodes, a first conductive surface in the transparent zone made from transparent material, and utilized as a guard for the surface having electrodes. The connecting tracks are arranged in a sandwich between a second and a third conductive surfaces utilized as second and third guards for these connecting tracks. Linking tracks are made from a transparent conductive material for linking the connecting tracks to electrodes of the surface having electrodes. The linking tracks are positioned between the electrodes when these linking tracks are situated on the detection surface; and positioned between the second and third guards when these linking tracks are in the access zone.
1. A human-machine interface device having a transparent detection zone and an access zone, said device comprising:
a surface having electrodes made from a conductive transparent material in the transparent detection zone;
conductive connecting tracks arranged in the access zone and connected to the surface having electrodes;
linking tracks made from a transparent conductive material for linking the conductive connecting tracks to electrodes of the surface having electrodes;
a first conductive surface made from transparent material in the transparent detection zone, utilized as a guard to eliminate parasitic capacitances for the surface having electrodes;
said conductive connecting tracks are arranged in the access zone in a sandwich between a second and a third conductive surfaces utilized as second and third guards to eliminate parasitic capacitances for said conductive connecting tracks, and
the linking tracks are arranged so that when a linking track borders at least one electrode on the transparent detection zone, said linking track is positioned between at least two electrodes, so that all linking tracks in the transparent detection zone are situated between electrodes.
2. The device according to claim 1 , wherein when a linking track is situated in the access zone, said linking track is positioned between the second and third guards.
3. The device according to claim 1 , wherein at least one of the second and third conductive surfaces is at the same guard potential as the first conductive surface.
4. The device according to claim 1 wherein one of the second and third conductive surfaces is a prolongation of the first conductive surface.
5. The device according to claim 1 , wherein the electrodes of the surface having electrodes and the first conductive surface utilized as a guard are designed from tin-doped indium oxide ITO.
6. The device according to claim 1 , wherein the electrodes of the surface having electrodes are rectangular in shape.
7. The device according to claim 1 , wherein the electrodes of the surface having electrodes are triangular in shape.
8. The device according to claim 1 , wherein the electrodes of the surface having electrodes are concave in shape.
9. The device according to claim 1 , wherein the first, second and third guards are designed based on a floating-bridge technology.
10. The device according to claim 1 , further comprising capacitive measurement electronics of the self-capacitance type.
11. The device according to claim 1 , further comprising at least one electrode is arranged on the side of the device outside of the transparent detection zone.
12. The device according to claim 11 , wherein said at least one electrode arranged on the side of the device is arranged in the third conductive surface.
13. A method implemented in an apparatus comprising a human-machine interface device as defined in claim 1 with a transparent detection zone superposed to a display screen on a face of said apparatus, comprising: detecting fingers placed on edges of said face and modifying functionalities on the display screen according to an arrangement of said detected fingers.
14. The method according to claim 13 , further comprising a number and a positioning of the detected fingers so as to identify a type of hand holding the apparatus.
15. The method according to claim 13 , further comprising, in the absence of detection of fingers on the edges, identifying whether the apparatus is placed on a support on a side of the face holding the transparent detection zone.
16. The method according to claim 13 , wherein an edge of the apparatus is used for detecting any movement of an object by means of electrodes of the surface having electrodes so as to initiate commands from within the apparatus.