Patent ID: 9600084
Date: 2017-03-21
CPC Classifications: G06F,H03K

Claim:
1. A keyboard including a plurality of key assemblies configured to be pressed by an input object, wherein a first subset of the plurality of key assemblies each comprises: a key cap; a first conductive portion disposed on the key cap, wherein the first conductive portion is configured to operate at a substantially constant voltage; a second conductive portion disposed on the key cap, wherein the second conductive portion is an electrically floating conductor; a base; a first electrode pair disposed underneath the key cap and on the base, the first electrode pair configured to generate a keystroke signal in response to movement of the first conductive portion on the key cap toward the base by the input object; and a second electrode pair disposed underneath the key cap and on the base, the second electrode pair configured to generate a finger presence signal in response to a change in capacitive coupling between a finger and the second conductive portion at the key cap, wherein the finger presence signal with no finger present at the key cap corresponds to a baseline value of the finger presence signal, and wherein the keystroke signal is used by a processing system to determine that the key cap is in a pressed position when the keystroke signal is above the baseline value.