Capacitance Touch Sensor Gap Compensation for In-Cell LCD
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Solution Overview
Problem
Conventional in-cell touch LCD panels misjudge touch events due to non-uniform sensing gaps caused by manufacturing errors and substrate bends, leading to inaccurate touch sensing operations.
Innovation Solution
A touch sensing apparatus and method that utilize capacitance touch sensors with a post-processing circuit to determine touch events by establishing a linear relation between voltage variations and sensing gap variations, ensuring uniform voltage changes regardless of sensing gap deviations from design standards, thereby preventing misjudgment of touch events.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional capacitance touch sensors are used in in-cell touch LCD panels, then the touch sensing function can be provided, but the touch event judgment accuracy deteriorates due to non-uniform sensing gaps caused by manufacturing errors and substrate bends
Solution Approach 1:
The patent changes the operating parameters of the capacitance touch sensor by introducing a compensation capacitor whose capacitance value is dynamically adjusted based on the sensing gap distance. The control circuit modifies the compensation capacitor's capacitance value according to the measured sensing gap, thereby compensating for non-uniform gaps and maintaining accurate touch event judgment across different regions of the display panel.
2Ease of manufacture
If the sensing gap varies due to manufacturing errors or substrate bends, then the device can be manufactured with relaxed precision requirements, but the voltage output becomes non-uniform leading to misjudgment of touch events
Solution Approach 1:
The patent implements a feedback mechanism where the control circuit continuously monitors the sensing gap distance and adjusts the compensation capacitor's capacitance value accordingly. This closed-loop feedback system ensures that voltage output remains uniform despite variations in sensing gap, as the compensation capacitor dynamically compensates for any deviations from the ideal gap distance.
3Reliability
If no compensation mechanism is used, then the device structure remains simple, but touch event detection becomes inaccurate when sensing gaps are non-uniform
Solution Approach 1:
The patent makes the compensation capacitor serve multiple functions: it compensates for non-uniform sensing gaps, maintains voltage output uniformity, and enables accurate touch event detection across the entire display panel. By integrating this compensation mechanism into the existing capacitance touch sensor structure, the system achieves reliable touch detection without requiring entirely new sensor designs.
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
The solution ensures accurate touch event detection by maintaining uniform voltage variations when the sensing gap variations are consistent, regardless of manufacturing errors, thus preventing misjudgment and improving the reliability of touch sensing operations.
Implementation Method 1
the capacitance-value of the touch sensing capacitor 110 can be altered with a pressing strength... the capacitance-value of the touch sensing capacitor 110 is inversely proportional to the distance between two electrodes thereof
Data Source
AI summary
A touch sensing apparatus and a touch sensing method are provided. The touch sensing apparatus includes a plurality of capacitance touch sensors and a post-processing circuit. Each of the capacitance touch sensors determines a value of an output current according to a distance between two electrodes of a touch sensing capacitor thereof. The post-processing circuit performs an integration operation for output currents to obtain a plurality of voltage values. The post-processing circuit further judge whether a touch event occurs according to a voltage difference between two voltage values corresponding to two capacitance touch sensors thereof, to further determine whether calculating a coordinate of a touch position. There is a linear relation between a variation of each of the voltage values and a variation of a distance between the two electrodes of the corresponding touch sensing capacitor.