| 摘要 |
The present invention concerns a method for determining multiple touch inputs on a resistive touch screen, such screen having a first layer (1A) and a second layer (1B), said first layer (1A) being adapted to be touched and said second layer (1B) having a plurality of power nodes (VI,..., Vn) which supply power to said second layer (1B), said first layer (1A) and said second layer (1B) having a planar geometry. The method is characterized in that it comprises the additional steps of supplying power to said lower layer (1B) through a plurality of controlled voltage generators (V1,..., Vn) to obtain a potential gradient vector (1D) for each voltage generator (VI,..., Vn), which is adapted to be oriented in said planar geometry (xy), sensing a base current value (II, In) delivered by each generator (VI,..., Vn) when said first layer (1A) is not touched anywhere, summing said base currents (II, In) of the same sign flowing into or out of each of said plurality of generators (VI,..., Vn) to obtain a first value (I?bias(9)), sensing a touch current value (?1', In') delivered by each generator (VI,..., Vn) when said first layer (1A) is touched at said first point (PI) and is also simultaneously touched at said second point (P2), summing said touch currents (?1', In') of the same sign flowing into or out of each of said plurality of generators (VI,..., Vn) to obtain a second value (l?in(0)), comparing said first value (l?bias(0)) and said second value (l?in(0)) to obtain a third value (I?aCq(O)) identifying the maximum current increase (Dmax) while the potential gradient vector is oriented in said planar geometry (x,y), determining a distance (d) between said two touch points (PI, P2) as a function of said third value (Dmax), processing said distance (d) to generate the coordinates (Plx,Ply;P2x,P2y) of said two touch points (P1,P2). |
