Touch Controller Signal Combining for I/Q Demodulation
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Solution Overview
Problem
Existing touch sensor devices face issues with inconsistent magnitude and phase measurements when demodulating signals with unknown phases, particularly in cases like active pen data reception, due to the limitations of single phase demodulation.
Innovation Solution
Implementing a processing system that combines signals from two sensor electrodes to perform simultaneous in-phase quadrature (I/Q) demodulation, allowing for the determination of signal magnitude information by combining in-phase and quadrature components, which mitigates the variability in output magnitude and phase measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If single phase demodulation is used, then device complexity is reduced, but measurement precision deteriorates due to varying output magnitude and inconsistent phase measurements
Solution Approach 1:
The system dynamically switches between single-phase demodulation mode and I/Q demodulation mode based on signal conditions. When signals with unknown phase are detected, the system transitions to I/Q demodulation to maintain measurement consistency, otherwise using simpler single-phase demodulation
Solution Approach 2:
The patent changes the demodulation parameters by introducing quadrature components (I and Q channels) when measurement consistency is required. This parameter change enables accurate magnitude and phase measurement of signals with unknown phase while maintaining device complexity management through conditional implementation
2Measurement precision
If I/Q demodulation is implemented, then measurement precision is improved, but device complexity increases due to additional circuitry requirements
Solution Approach 1:
The I/Q demodulation circuit is designed to perform multiple functions: it can process signals with known phase (degenerating to single-phase demodulation) and signals with unknown phase (full I/Q demodulation), making the circuit universally applicable to different signal conditions without requiring separate dedicated circuits
Solution Approach 2:
The system dynamically adapts its operation mode, switching between single-phase and I/Q demodulation based on signal characteristics. This dynamic behavior allows the system to use complex I/Q demodulation only when necessary, thereby managing overall device complexity while maintaining measurement precision when needed
3Reliability
If signal combining is performed, then reliability is improved through consistent measurements, but processing time increases due to additional signal combination and demodulation steps
Solution Approach 1:
The system performs preliminary signal combining from multiple sensor electrodes before demodulation. By pre-combining signals, the system reduces the number of individual demodulation operations needed, thereby maintaining measurement consistency while minimizing processing time
Solution Approach 2:
Multiple sensor electrode signals are merged into a combined signal before I/Q demodulation. This merging operation consolidates multiple measurement paths into a single processing stream, maintaining reliability through consistent measurements while reducing overall processing time compared to separate demodulation of each signal
Data Source
AI summary
An input device is configured to detect signals from of an input object. Examples include acquiring a first signal on a first sensor electrode of the input device; acquiring a second signal on a second sensor electrode of the input device; combining the first signal and the second signal to produce a combined signal; demodulating the combined signal to determine an in-phase component of the combined signal and a quadrature component of the combined signal; and combining the in-phase component and the quadrature component to determine signal magnitude information.