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Stylus to host synchronization

  • US 10,678,355 B2
  • Filed: 07/19/2018
  • Issued: 06/09/2020
  • Est. Priority Date: 02/15/2012
  • Status: Active Grant
First Claim
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1. A signal processing device configured to be coupled to a sensor array including a plurality of first electrodes disposed along a first direction and a plurality of second electrodes disposed along a second direction different from the first direction, the signal processing device comprising:

  • a signal generator configured to generate a first sensor transmission signal that is code modulated; and

    a processor coupled to the signal generator and configured to;

    transmit the first sensor transmission signal that is code modulated capacitively via the sensor array to an active stylus;

    receive capacitively via the sensor array a stylus transmission signal transmitted from the active stylus in response to the first sensor transmission signal;

    detect the active stylus on the sensor array based on the stylus transmission signal received via the sensor array during a first time interval;

    detect a position pointed to by the active stylus on the sensor array capacitively during a second time interval using the first electrodes and the second electrodes after confirming that the active stylus is present on the sense array during the first time interval, the second time interval being different from the first time interval;

    transmit a second sensor transmission signal via the first electrodes of the sensor array in a third time period that does not overlap with the first and second time periods; and

    receive one or more signals indicative of a presence of a passive object via the second electrodes of the sensor array in a fourth time period, which does not overlap with the first and second time periods, wherein the third time period overlaps with the fourth time period,wherein the stylus transmission signal transmitted from the active stylus to the sensor array is modulated using one or more of;

    a signal amplitude, a signal frequency, and a signal phase so that the stylus transmission signal is differentiated from the first sensor transmission signal that is code modulated in signal types,wherein a timing when the active stylus transmits the stylus transmission signal to the sensor array is determined responsive to the first sensor transmission signal that is code modulated transmitted to the active stylus.

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