Touch Sensor Reference Code Phase Update for RC Delay Compensation
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Solution Overview
Problem
Existing touch sensors face challenges in accurately detecting touch positions due to resistive-capacitive (RC) delays in driving signals, which can break the orthogonality of reference codes and increase noise in sensing signals.
Innovation Solution
A touch sensor that includes a touch sensing area with driving and sensing electrodes, a driving signal generator that determines phases of driving signals based on a reference code and updates it at predetermined time points to compensate for RC delays, and a touch processor that determines touch positions based on sensing signals and the reference code.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If driving signals are supplied to driving electrodes for high-speed touch sensing, then sensing speed is improved, but RC delays occur in the driving signals which break orthogonality of reference codes and increase noise
Solution Approach 1:
The patent applies preliminary action by updating the reference code at predetermined time points (e.g., at the beginning of each driving period or unit period) to pre-compensate for RC delays before they affect the orthogonality of driving signals. This proactive update ensures that the reference code remains synchronized with the actual signal phases despite RC delays, thereby maintaining measurement precision while enabling high-speed touch sensing.
Solution Approach 2:
The patent changes the parameter of the reference code (specifically, the phase values in the reference code matrix) to compensate for RC delays. By adjusting the reference code values based on predetermined time points and RC delay characteristics, the system maintains orthogonality of driving signals even at high speeds, thus resolving the contradiction between sensing speed and measurement precision.
2Reliability
If reference code is updated frequently to compensate for RC delays, then orthogonality is maintained and noise is reduced, but device complexity increases
Solution Approach 1:
The patent implements periodic action by updating the reference code at predetermined periodic time points (e.g., at the start of each driving period or unit period). This regular, periodic update strategy maintains orthogonality and reduces noise without requiring continuous or complex real-time adjustments, thereby limiting device complexity while ensuring reliability.
Solution Approach 2:
The reference code is updated in advance at predetermined time points before RC delays can significantly degrade orthogonality. This preliminary update approach maintains reliability while avoiding the need for complex continuous monitoring and adjustment mechanisms, thus balancing reliability with manageable device complexity.
3Productivity
If driving signals are supplied in parallel to multiple driving electrodes, then productivity is improved, but RC delays vary across different electrodes causing phase differences and noise
Solution Approach 1:
The patent applies local quality by updating the reference code specifically for each driving electrode group at predetermined time points, accounting for local RC delay characteristics of each electrode. This localized reference code update ensures that phase differences caused by varying RC delays across different electrodes are compensated, maintaining measurement precision while enabling parallel driving of multiple electrodes for high productivity.
Solution Approach 2:
The reference code is updated in advance for each driving electrode group before parallel signal transmission, pre-compensating for electrode-specific RC delays. This preliminary action ensures that all electrodes maintain correct phase relationships despite varying RC delays, resolving the contradiction between productivity and measurement precision in parallel driving.
Data Source
AI summary
A touch sensor including: a touch sensing area including driving electrodes and sensing electrodes; a driving signal generator which determines phases of driving signals based on a reference code and supplies the driving signals to the sensing electrodes, wherein the driving signals are sine waves; and a touch processor which receives sensing signals according to the driving signals from the sensing electrodes and determines a touch position based on the sensing signals and the reference code, wherein the driving signal generator controls the phases of the driving signals by updating the reference code at a predetermined time point.