Patent Document ID: 20020035701
Application ID: 09948099
Patent Flag: 0

Claim One:
1. A capacitive sensing system for sensing the presence of an object or body portion in contact with or close proximity to another object, comprising: a first conductor capacitively coupled to a ground to thereby form a scoop capacitor having a capacitance which varies in relation to the proximity of said object or body portion to said conductor; a pair of second and third conductors forming a bucket capacitor having a capacitance which is larger than a maximum capacitance of said scoop capacitor; an input threshold switch; switching means for selectively: connecting at least one of said scoop capacitor and bucket capacitor to a voltage source to charge said at least one capacitor, varying the charge of said bucket capacitor in relation to a relative size of said scoop capacitor, and applying a voltage of said bucket capacitor to said input threshold switch; detector means for detecting an input state of said input threshold switch; determining means for determining a value (TouchVal) relating to a number of cycles of said varying of the bucket capacitor charge, corresponding to a detection of a transition of said input threshold switch by said detector means; and signal generating means for generating, based upon TouchVal, a signal indicative of an ON state wherein said object or body portion is in contact with or close proximity to said another object, and an OFF state wherein said object or body portion is not in contact with or close proximity to said another object.