Patent ID: 7786981
Filing Date: 2010-08-31
Classification: G06F

Abstract:
1. A method for determining a location of a contact to a touch sensor comprising: detecting the contact to the touch sensor, the touch sensor comprising at least three adjoining sensor pads arranged about a common center point in an iris pattern, each sensor pad having at least one continuous, arcuate edge that spirals about outward from a first point on the common center point to a second point on an outer circular boundary such that the edges comprise the iris pattern and form an overlapping relationship amongst the sensor pads, wherein the first and second points are between approximately 120 and approximately 180 degrees apart and a curve of the continuous, arcuate edge is such that any radius from the common center point to the outer circular boundary crosses over at least two sensor pads; measuring a capacitance change in two or more of the sensor pads resulting from the contact; determining a continuously variable contact ratio for the two or more of the iris-shaped arcuate edged sensor pads based on a ratio of the capacitance change; assigning an angular position in accordance with the contact ratio by comparing the contact ratio to discrete angular positions residing in a lookup table; and corresponding sensor values in the lookup table to a plurality of discrete angular positions of contact, the touch sensor is correlated with a relative contribution of each of the sensor pads to a total capacitance increase across all of the sensor pads based on the overlapping relationship amongst the sensor pads, wherein the relative contribution of each of the sensor pads is represented as a percentage of the total capacitance increase, the total capacitance increase across all of the sensor pads equaling 100%.