Capacitive Touch Controller Noise Extraction for Accuracy
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Solution Overview
Problem
Capacitive overlay touch panels face challenges in accurately detecting touch inputs due to noise interference from the display device and physical curling, especially in larger panels, which affects the accuracy of touch detection and multi-touch inputs.
Innovation Solution
An apparatus and method that utilize a touch element with multiple detecting electrodes and a controller to receive, group, and process detection signals, extracting the maximum signal value and adjusting for noise by deducting a signal value limit to determine the presence and coordinates of touch inputs, thereby improving detection accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the touch panel is enlarged to support larger display areas, then the coverage area is increased, but the physical curling increases and noise from the display device correlation worsens
Solution Approach 1:
The patent extracts and removes the harmful noise component from the detection signal by calculating a reference value that represents the noise level and subtracting it from the raw detection signals. This separation of useful signal from harmful noise allows the touch panel to maintain high detection accuracy even when enlarged
Solution Approach 2:
The patent changes the parameter of signal processing by introducing dynamic threshold values and reference signal subtraction. Instead of using fixed detection thresholds, the system adjusts detection parameters based on the calculated noise reference, enabling accurate touch detection across varying panel sizes and noise conditions
2Area of stationary object
If the touch panel is enlarged, then the coverage area is increased, but the physical curling increases affecting detection accuracy
Solution Approach 1:
The patent extracts the noise component caused by physical curling and display correlation from the detection signals. By calculating a reference value that represents this noise and subtracting it, the system recovers the true touch signal, maintaining measurement precision regardless of panel size or curling degree
Solution Approach 2:
The system uses feedback by continuously monitoring detection signals, calculating reference noise values, and adjusting the detection threshold dynamically. This closed-loop approach compensates for variations in panel physical state, ensuring consistent detection accuracy across different panel sizes and curling conditions
3Speed
If the detection signal is used directly for touch determination, then the processing speed is maintained, but the accuracy of touch presence determination deteriorates due to noise
Solution Approach 1:
The patent performs preliminary action by calculating the reference noise value and establishing adjusted detection thresholds before actual touch detection. This pre-processing of detection parameters ensures that when touch signals are evaluated, the accuracy is already optimized, allowing fast real-time detection without sacrificing precision
Solution Approach 2:
The patent introduces an intermediary reference value that mediates between the raw detection signal and the final touch determination. This reference value acts as a bridge, allowing the system to process signals quickly while maintaining high accuracy by comparing against the noise-compensated threshold
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
Enhances the accuracy of touch detection by effectively filtering out noise interference, particularly from the display device, and improves the reliability of multi-touch inputs on larger panels.
Implementation Method 1
uses a principle that capacity is varied by touch input applied to a transparent conductive film or glass. As capacitances are generated, more electric charge accumulates in coordinates input by touch than coordinates not input by touch
Data Source
AI summary
There is disclosed an apparatus for detecting touch including a touch element comprising a plurality of touch detecting electrodes arranged therein, a touch element controller for acquiring detection signals from the touch detection electrodes and determining presence of touch in the touch element, wherein the touch element controller includes a receiving unit for receiving the detection signals from the touch detection electrodes and grouping the detection signals into one or more detection signal groups, a memory for storing a detection signal value limit, a signal extracting unit for extracting the maximum detection value out of the detection signal values of the detection for each of the detection signals, a calculating unit for calculating an adjustment variable by deducting the detection signal value limit from the maximum detection signal value for each of the detection groups, and a touch determination unit for determining presence of touch in the touch element, using the adjustment variable.