Capacitive touch sensor system

摘要

A method of matrix sensing using delay-based capacitance sensing, including using X-axis lines as active lines for capacitance measurements and using Y-axis lines as a disturbance to identify the location of a touch in a key matrix is disclosed. A sensing signal is applied to the X-axis lines, and a disturbance signal is applied to the Y-axis lines. If a location is touched, cross-capacitance is reduced, which is measured by sweeping data along the X-axis lines.

主权项

1. A method of matrix sensing using delay-based capacitance sensing, the method comprising:
applying a sensing signal to a plurality of first-axis lines as active lines; applying a disturbance signal to a plurality of second-axis lines; and identifying a location of a touch by measuring a change in cross-capacitance at intersections between the first-axis and second-axis lines, wherein applying the sensing signal comprises applying a series of first pulses to one of said first-axis lines, each first pulse having a leading edge transition in a first direction and a trailing edge transition in a second direction, and wherein applying the disturbance signal comprises applying individual second pulses in a sequential manner swept across the plurality of second-axis lines, each second pulse having a leading edge transition in the second direction and a trailing edge transition in the first direction, and the leading and trailing edges of each individual second pulse being substantially aligned with the leading and trailing edges of one corresponding first pulse of said series of first pulses.