Touch Sensor Circuits for Simultaneous Multi-Mode Capacitance Sampling

The patent implements continuous simultaneous sampling of self capacitance, mutual capacitance, and pen signals through dedicated circuit paths. The self capacitance signal is continuously driven and sampled on all rows and columns simultaneously, while mutual capacitance and pen signals are sampled in the same time frame, eliminating sequential measurement delays and providing continuous touch detection across all modes.

The patent segments the sampling system into independent parallel paths: one path continuously samples self capacitance signals on all electrodes simultaneously, another path samples mutual capacitance signals between row and column electrodes, and a third path samples pen signals. This segmentation allows each mode to be measured independently and simultaneously without interfering with others, resolving the time conflict between modes.

The patent introduces dedicated driver circuits and receiver circuits as intermediary components between the signal sources and the electrodes. These intermediaries include differential signaling paths, balanced/unbalanced conversion circuits, and impedance matching networks that isolate the simultaneous multi-frequency signals from each other, preventing parasitic coupling and noise interference while enabling simultaneous transmission on multiple channels.

The patent employs different frequency parameters for different signal modes: self capacitance signals use one frequency range, mutual capacitance signals use another frequency range, and pen signals use a third frequency range. By assigning distinct frequency parameters to each mode, the system can simultaneously transmit multiple signals without interference, as each frequency can be independently detected and processed.

The patent replaces the traditional mechanical integration process with electronic correlation detection. Instead of repeatedly integrating signals over many cycles to overcome parasitic capacitance, the system uses correlation between the transmitted signal and received signal to directly measure mutual capacitance. This substitution of the measurement mechanism eliminates the need for lengthy integration cycles while maintaining accuracy.

The patent implements feedback circuits that continuously monitor the measured capacitance values and adjust the measurement parameters in real-time. The system uses feedback to compensate for parasitic capacitance effects dynamically during the measurement process, rather than requiring multiple integration cycles to average out the parasitic effects. This feedback mechanism accelerates the determination process while maintaining precision.