Capacitance-variation-sensitive touch sensing array system

A capacitance-variation-sensitive touch sensing array system comprising

• an array of electrodes with each electrode including a connected series of conductive tabs;
• a touch responsive panel overlying and coextensive with the electrode array for varying the capacitance between a plurality of the electrodes and ground simultaneously upon the interior area of the touch responsive panel being touched by an operator;
• an array of drive lines capacitively coupled to the electrodes, with individual drive lines being coupled to a plurality of the electrodes;
• drive means for applying drive signals to the drive lines to drive the electrodes coupled thereto;
• an array of sense lines capacitively coupled to the electrodes to derive sense signals from the electrodes when drive signals are applied to the drive lines, with each of said sense lines being so coupled to a plurality of the electrodes as to be interconnected via unique combinations of electrodes to said drive lines such that the sense lines derive unique combined patterns of variations in said sense signals in response to touching distinct locations on the panel;
• means coupled to the sense lines for sensing said patterns of variations in said sense signals;
• and
• means coupled to the sensing means for processing the sense signals to provide an estimate of the location of operator touch;
• whereby the number of said distinct locations of operator touch that can be estimated exceeds twice the product of the number of drive lines and the number of sense lines.

A capacitance-variation-sensitive touch sensing array system comprising

• an array of electrodes with each electrode including at least one conductive tab;
• an array of keys with each key overlying at least one tab of at least one electrode of the electrode array for varying the capacitance between each said overlaid electrode and ground upon the key being touched by an operator;
• drive means for applying drive signals to drive the electrodes;
• an array of sense lines coupled to the electrodes;
• sensing means coupled to each of the sense lines to derive a digital sense value from each of the respective sense lines when drive signals are applied to the electrodes, which digital sense value is dependent on variations in the electrode to ground capacitance of at least one of the electrodes, with said sense lines being so coupled to the electrodes as to be interconnected via the electrodes to said drive lines such that said sense lines derive unique combined patterns of variations in said sense signals in response to actuation of each of the keys;
• and
• means for processing the digital sense values iteratively to ascertain the values of variations in the digital sense values and for processing the variation values in two stages, the first stage being a feature extraction stage in which a search is made for said digital sense value variations that may be indicative of a given key being touched and the second stage being a confirmation stage which is carried out when an affirmative determination is made in the first stage and in which said digital sense value variations for which said affirmative determination was made during the feature extraction stage are processed together with a predetermined group of digital sense value variations to determine whether said unique combined pattern of digital sense value variations characteristic of said given key being touched by an operator is or is not present.