A method for operating a touchscreen system, the method comprising:
- cooperatively energizing a resistive pattern attached to a backside of a dielectric sheet at a plurality of communicative coupling points and generating a plurality of amplitude ramped fields that each communicatively couple through the dielectric sheet to a frontside of the dielectric sheet, the cooperatively energizing the resistive pattern including:
- applying full scale AC signals to a first set of the plurality of communicative coupling points and virtual ground signals to a second set of the plurality of communicative coupling points to produce a first amplitude ramped field extending across the dielectric sheet in a first direction at a first time,
- applying the virtual ground signals to the first set of the plurality of communicative coupling points and the full scale AC signals to the second set of the plurality of communicative coupling points to produce a second amplitude ramped field extending across the dielectric sheet in the first direction at a second time subsequent to the first time, the second amplitude ramped field having an inversed gradient with respect to the first amplitude ramped field,
- applying the full scale AC signals to a third set of the plurality of communicative coupling points and the virtual ground signals to a fourth set of the plurality of communicative coupling points to produce a third amplitude ramped field extending across the dielectric sheet in a second direction perpendicular to the first direction a third time subsequent to the second time, and
- applying the virtual ground signals to the third set of the plurality of communicative coupling points and the full scale AC signals to the fourth set of the plurality of communicative coupling points to produce a fourth amplitude ramped field extending across the dielectric sheet in the second direction at a fourth time subsequent to the third time, the fourth amplitude ramped field having an inversed gradient with respect to the third amplitude ramped field;
- measuring current flow at the plurality of communicative coupling points coupled to the resistive pattern on the backside of the dielectric sheet at each of the first, second, third and fourth times;
- removing any substantially purely resistive current portion that is injected at the plurality of communicative coupling points and removing current not having an unbalanced capacitive component thereby generating a first unbalanced capacitive component at the first time, a second unbalanced capacitive component at the second time, a third unbalanced capacitive component at the third time and a fourth unbalanced capacitive component at the fourth time;
- converting the first, second, third and fourth unbalanced capacitive component, being substantially attributable to a user's interaction or touch on the frontside of the dielectric sheet, to first, second, third and fourth digital signals, respectively;
- deriving, in a digital signal processor, a location of the user's interaction or touch on the frontside of the dielectric sheet deriving including:
- deriving a first ratio of the first digital signal to a sum of the first digital signal and the second digital signal to produce a first position of the location in the first direction, and
- deriving a second ratio of the third digital signal to a sum of the third digital signal and the fourth digital signal to produce a second position of the location in the second direction.