Digital filtering and spread spectrum based interference mitigation for mutual and self capacitance panel

摘要

A touch screen controller for a capacitive touch screen panel having row conductors intersecting column conductors to form pixels, the touch screen controller comprising: a transmitting unit configured to drive the row conductors with signals formed from an excitation matrix, and a receiving unit configured to sense signals from the column conductors and to determine the capacitance of the pixels using the sensed signals. In some embodiments, the receiving unit is configured to apply zero-ISI filtering to the sensed signals prior to the capacitance of the pixels being determined. In some embodiments, the transmitting unit is configured to spread each bit of the row drive signals with a pseudo-noise code, and the receiving unit is configured to de-spread the sensed signals with the pseudo-noise code. In some embodiments, the transmitting unit is configured to pulse shape the row drive signals.

主权项

1. A touch screen controller for a capacitive touch screen panel having a plurality of row conductors intersecting with a plurality of column conductors to form a matrix of pixels, each pixel configured to have a capacitance, the touch screen controller comprising:
a transmitting unit configured to drive the row conductors with row drive signals formed from an excitation matrix, the excitation matrix including a cyclic extension at the end of each row, the cyclic extension for each row repeating a sequence of elements taken in order from a beginning portion of the row, the sequence of elements including a number of elements that exceeds a maximum time shift over the capacitive touch screen panel; and a receiving unit configured to sense signals from the column conductors and to determine the capacitance of the pixels using the sensed signals, wherein the receiving unit is configured to apply at least one of low pass filtering, Raised Cosine filtering, or Bessel filtering to the sensed signals prior to the capacitance of the pixels being determined.