Touch Sensor Signal Integration for Display Noise Cancellation
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Solution Overview
Problem
Current touch sensors face challenges in accurately detecting the presence and position of objects within touch-sensitive areas due to noise interference from display systems, particularly in pixel patterns like dot inverse and double dot inverse patterns, which can lead to flicker and reduced touch measurement performance.
Innovation Solution
The implementation of a specific integration sequence by the touch sensor controller, involving alternating positive and negative integrations synchronized with HSYNC signals, effectively cancels out display noise and flicker, ensuring accurate touch detection without degrading measurement performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a touch sensor uses conventional integration methods to detect touch input, then touch detection capability is maintained, but display noise and flicker degrade measurement accuracy
Solution Approach 1:
The patent applies periodic action by implementing an integration sequence that alternates between positive and negative integration phases synchronized with the display refresh rate. This periodic integration approach allows the system to sample capacitive values at specific intervals within each display refresh cycle, thereby capturing consistent measurement points that are less susceptible to display-induced noise and flicker.
Solution Approach 2:
The patent converts the harmful effect of display noise into a beneficial measurement strategy by synchronizing the integration sequence with the display refresh cycle. By aligning the positive and negative integration phases with the periodic nature of display updates, the system transforms the previously harmful periodic noise into a predictable pattern that can be systematically compensated for and eliminated through differential measurement.
2Measurement precision
If the touch sensor controller implements noise cancellation techniques, then measurement accuracy improves, but processing complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-configuring the integration sequence to alternate between positive and negative integration phases before actual touch measurement begins. This predetermined integration pattern is synchronized with the display refresh cycle, allowing the controller to systematically cancel display noise through pre-planned differential measurement without requiring complex real-time processing or adaptive algorithms.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach significantly reduces noise and flicker in touch measurements, maintaining high accuracy and efficiency across various display pixel patterns, thereby enhancing the reliability of touch sensor systems.
Implementation Method 1
a change in capacitance may occur within the touch screen at a position of the touch sensor of the touch screen that corresponds to the position of the object within the touch sensitive area of the touch sensor
Data Source
AI summary
In certain embodiments, a method includes performing a first positive integration by sensing a first rising edge of a charging signal of a touch sensor during a first synchronization period and performing a first negative integration by sensing a first falling edge of the charging signal during a second synchronization period. The method also includes toggling the charging signal, resulting in a second rising edge of the charging signal during the second synchronization period. The method further includes performing a second negative integration by sensing a second falling edge of the charging signal during a third synchronization period and performing a second positive integration by sensing a third rising edge of the charging signal during a fourth synchronization period. The first integrations are associated with a first sample measurement and the second integrations are associated with a second sample measurement.