Projected capacitive touch sensor circuit

A method for measuring a mutual capacitance between electrodes disposed on a substrate, comprising:

• generating a periodic pulse;
• communicating the pulse to a drive electrode;
• and
• measuring a mutual capacitance between the drive electrode and a sense electrode at a point of intersection between the drive electrode and the sense electrode, wherein measuring further comprises:
• continuously integrating a sense signal from the sense electrode during a time required for determining the mutual capacitance to thereby generate an integrated sense signal;
• periodically sampling the integrated sense signal at a first time that is just prior to a falling edge of the pulse, and at a second time that is just prior to a rising edge of the pulse to thereby sample a maximum value and a minimum value of the integrated sense signal;
• digitizing the maximum value and the minimum value;
• and
• determining a difference between the maximum value and the minimum value to thereby determine a mutual capacitance between the drive electrode and the sense electrode.

A touch sensitive system, comprising:

• a substrate having disposed thereon a plurality of drive electrodes and a plurality of sense electrodes;
• and
• a circuit for determining a location of a touch, the circuit comprising:
• a drive circuit configured to generate a periodic pulse and to communicate the pulse to a drive electrode;
• and
• a sense circuit configured to measure a mutual capacitance between the drive electrode and a sense electrode at a point of intersection between the drive electrode and the sense electrode, wherein the sense circuit comprises:
• an integrator circuit with an input section that is in continuous electrical communication with the sense electrode;
• a switch circuit with an input in electrical communication with an output of the integrator circuit and an output in electrical communication with an analog-to-digital converter, wherein the switch operates to momentarily communicate an output signal of the integrator circuit to the analog-to-digital at a first time that is prior to a falling edge of the pulse, and at a second time that is prior to a rising edge of the pulse to thereby sample a maximum value and a minimum value of the output signal;
• and
• computational logic configured to determine a difference between the maximum value and the minimum value to thereby determine a mutual capacitance between the drive electrode and the sense electrode.