Dynamically reconfigurable capacitive sensor array

The keyboard of claim 10, wherein:

• the processing system further comprises an external switch and a microcontroller configured to selectively connect the three electrodes, respectively, to the transmitter circuitry and receiver circuitry through the external switch.

The keyboard of claim 13, wherein the compressible dielectric and the capacitive sensor exhibit an area of contact which increases during a down stroke of the key cap, thereby changing at least the first variable capacitance when in the first mode.

The keyboard assembly of claim 14, wherein the area of contact increases substantially monotonically with downward key cap motion.

A processing system for a keyboard input device of the type including a plurality of key assemblies each having a key cap and a capacitive sensor disposed underneath the key cap, the processing system configured to be communicatively coupled to each of the capacitive sensors and configured to selectively operate each capacitive sensor in a first mode and a second mode;

• wherein the first mode operates the capacitive sensor in a fine pitch configuration and determines a first variable capacitance, and the second mode operates the capacitive sensor in a coarse pitch configuration and determines a second variable capacitance;
• and
• wherein key cap motion is determined based on the first variable capacitance and finger presence is determined based on the second variable capacitance.