Digitiser

摘要

A digitiser includes a grid of conductors having excitation conductors and detection conductors. Excitation circuitry applies excitation signals to selected excitation conductors; measurement circuitry obtains measurements from selected detection conductors; and processing circuitry processes measurements obtained by the measurement circuitry to detect one or more objects positioned adjacent the grid of conductors. The excitation circuitry may be arranged to operate in a cyclic manner to select each of the excitation conductors during an excitation cycle, wherein an excitation cycle includes a sequence of excitation intervals during each of which a different pair of neighboring excitation conductors is selected by the excitation circuitry and to which complementary excitation signals are applied. The excitation circuitry is arranged to polarity modulate each excitation signal using a polarity control signal so that the polarity of the excitation signal applied to a selected conductor changes during a time that the excitation conductor is selected.

主权项

1. A digitiser comprising:
a grid of conductors having a plurality of excitation conductors and a plurality of detection conductors; excitation circuitry for applying excitation signals to selected excitation conductors; measurement circuitry for obtaining measurements of signals obtained from selected detection conductors; an analog to digital converter for converting analog measurements obtained by the measurement circuitry into digital measurement values; a memory for storing the digital measurement values; and processing circuitry for processing digital measurement values stored in the memory to detect one or more objects positioned adjacent the grid of conductors; wherein the digital measurement values stored in the memory comprise digital differential measurement values and wherein the processing circuitry is arranged to:
process the digital differential measurement values stored in the memory to identify one or more possible areas of touch and, for each possible area of touch, a first start point and a first end point for the possible area of touch;generate digital integrated measurement values by combining digital differential measurement values using the identified first start point and the first end point to restrict the integration of the digital differential measurement values to the digital differential measurement values from the identified first start point to the identified first end point;process the digital integrated measurement values to identify one or more possible areas of touch, and for each possible area of touch, a second start point and a second end point for the possible area of touch; andgenerate digital double integrated measurement values by combining digital integrated measurement values using the identified second start point and the second end point to restrict the combining of the digital integrated measurement values to the digital integrated measurement values from the identified second start point to the identified second end point.