Noise reduction for touch sensor system with active stylus

摘要

A touch sensor may overlap a display. A transparent shield layer that is grounded around its edges may be interposed between the display and the touch sensor to help prevent noise from display data lines from reaching the touch sensor. The data lines may extend along a first dimension. The touch sensor may have first elongated electrodes that extend along the first dimension and second elongated electrodes that extend along a second dimension that is perpendicular to the first dimension. The second electrodes may be interposed between the first electrodes and the data lines. Pen present electrodes may be used to gather pen present data associated with a stylus on the touch sensor. Adjacent noise sensors may collect noise data that is removed from the pen present data.

主权项

1. Apparatus that is responsive to input from a stylus, comprising:
a touch sensor having edges and having a plurality of electrodes; and touch sensor circuitry that processes signals from the plurality of electrodes, wherein the touch sensor circuitry obtains signal data from the plurality of electrodes including pen present data from pen present electrodes where the stylus is located on the touch sensor and noise data from noise electrodes adjacent to the pen present electrodes, wherein the touch sensor circuitry includes a processor that removes the noise data from the pen present data to produce noise-removed pen present data, wherein the noise electrodes include at least four electrodes adjacent to the pen present electrodes, and wherein the processor includes a noise correction module that removes the noise data from the pen present data by computing a mean of the noise data on the noise electrodes.