Capacitive pointing stick apparatus for symbol manipulation in a graphical user interface

An apparatus as recited in claim 2, wherein the articulating member includes:

• an anchoring member rigidly coupled to the planar member;
• a movable member which is movable responsive to user manipulation thereof;
• and
• a coupling member, physically coupled between the anchoring member and the movable member, the coupling member being flexible to allow movement of the movable member relative to the anchoring member.

An apparatus for sensing manipulation by a user and for producing signals related to the manipulation in X and Y directions, the apparatus comprising:

• an articulating member which articulates responsive to user manipulation thereof, the articulating member including an electrically conductive member;
• a plurality of sensing electrodes disposed about the articulating member to face the electrically conductive member, whereby respective capacitances exist between the electrically conductive member and respective ones of the sensing electrodes, the capacitances having values which vary related to articulation for the articulating member;
• calibration means applied to individual articulation signals to provides a unique scaling value for each articulation signal, wherein said scaling value is calculated from a set of reference values, at least one reference value for each sensing electrode, that are dynamically updated;
• and
• an oscillator circuit for each sensing electrode, wherein the frequency of the oscillator is dependent on the value of the respective capacitance, selection means to sequentially enable each oscillator in a temporal sequence.