3.4 Interpolated Sensors

An interpolated sensor utilizes the touch delta of two or more adjacent sensor nodes arranged in a row to calculate the position of a touch contact along that row. The sensor layout is designed and the threshold configured in such a way that a contact anywhere along the sensor will cause:

  1. A touch delta exceeding the threshold on at least one sensor node. The node with the strongest touch delta is determined to be the center node of the touch contact and identified the approximate location of the touch contact.
  2. Some touch delta on neighboring nodes, used for position interpolation between nodes. The relative delta on the nodes to the left and right of the center node are used to adjust the calculated touch position towards the side with the strongest delta.

An interpolated sensor may be formed into any physical shape, with or without a wrap-around from the last sensor to the first. A sensor with wrap-around is configured as a ‘Wheel’, while one without is configured as a ‘Slider’. In the case of the wheel, a touch contact centered on the 1st key uses the last key for ‘left’ interpolation and vice versa while the slider option implements a dead band at the ends.