Carrier Touch Sensing Phase Calibration Circuit
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Solution Overview
Problem
Carrier touch sensing systems face issues with phase delays due to varying characteristics of touch panels, leading to incorrect touch signals when integrated with electronic devices, necessitating effective phase calibration and demodulation methods.
Innovation Solution
A carrier touch sensing system that includes a driving circuit, touch panel, and demodulation circuit capable of performing in-phase and quadrature demodulations to generate and store phase delay information, switching between phase calibration and normal scan modes to ensure accurate touch signal generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If carrier signals are used instead of impulse signals to improve touch control functionality, then touch control function is improved, but phase delays occur due to different characteristics of the touch panel causing wrong touch signals
Solution Approach 1:
The patent applies preliminary action by performing phase calibration before normal touch sensing operations. The system first inputs calibration signals to measure and store phase delay information, then uses this pre-acquired information to compensate for phase delays during subsequent touch detection, ensuring accurate touch signals from the start of operation.
Solution Approach 2:
The patent implements feedback by measuring the actual phase delays of carrier signals during calibration mode, storing this information, and then using it to compensate for phase delays during normal scan mode. This closed-loop approach continuously corrects for phase variations caused by different touch panel characteristics.
2Measurement precision
If phase calibration is performed to maintain signal integrity under varying operating conditions, then touch signal accuracy is improved, but additional calibration operations are required increasing system complexity
Solution Approach 1:
The patent merges the phase calibration function with the existing touch sensing system by integrating calibration signal input and phase delay measurement capabilities into the demodulation circuit. The same hardware infrastructure is used for both calibration operations and normal touch detection, avoiding the need for separate dedicated calibration hardware.
Solution Approach 2:
The demodulation circuit is designed with multi-functionality to perform both calibration mode operations (measuring phase delays) and normal scan mode operations (detecting touch events). This universal circuit reduces overall system complexity by eliminating the need for separate dedicated calibration hardware.
3Measurement precision
If in-phase and quadrature demodulations are performed to generate phase delay information, then phase calibration accuracy is improved, but demodulation circuit complexity increases
Solution Approach 1:
The patent segments the demodulation process into two distinct modes: calibration mode where in-phase and quadrature demodulations are performed to measure phase delays, and normal scan mode where only in-phase demodulation is needed using pre-stored phase delay information. This segmentation allows complex operations to be performed only when necessary.
Solution Approach 2:
The system employs periodic action by performing comprehensive in-phase and quadrature demodulations periodically during calibration mode, then using the stored phase delay information for efficient in-phase demodulation during normal operation. This reduces the frequency of complex computational operations.
Data Source
AI summary
A carrier touch sensing system includes a demodulation circuit coupled to a touch panel, used for performing in-phase and quadrature demodulations to a plurality of carrier sensing signals to generate and store a plurality of phase delay information if the carrier touch sensing system operates in a phase calibration mode. The demodulation circuit is further used for performing in-phase demodulation to the plurality of carrier sensing signals according to the plurality of phase delay information to generate a plurality of touch signals if the carrier touch sensing system operates in a normal scan mode.