Touch Panel Electrode Pairing for External Noise Cancellation
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Solution Overview
Problem
Existing touch panels and display units suffer from erroneous detection due to external noise, particularly when the user acts as an antenna and transmits noise to the panel via their finger or pen.
Innovation Solution
The implementation of a touch panel design that includes a plurality of detection scan electrodes and detection electrodes with different ratios of fringe capacitance to total capacitance, allowing for the elimination of external noise by calculating the difference between detection signals from these electrodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a capacitive element is used to detect touch by reading surface electric field changes, then touch detection capability is achieved, but the system becomes susceptible to external noise causing erroneous detection
Solution Approach 1:
The patent applies local quality by creating two types of detection electrodes with different capacitance characteristics. The first detection electrode has a different ratio of fringe capacitance to total capacitance compared to the second detection electrode. This local differentiation allows each electrode type to respond differently to external noise, enabling noise cancellation through differential measurement while maintaining touch detection capability.
Solution Approach 2:
The patent converts the harmful effect of external noise into a beneficial feature by using differential measurement. Since both detection electrodes are affected by external noise in similar ways, subtracting their signals cancels out the common-mode noise while preserving the differential touch signal. This transforms the noise vulnerability into a noise-rejection mechanism.
2Reliability
If multiple detection electrodes with different capacitance ratios are implemented, then external noise elimination is achieved, but device complexity increases
Solution Approach 1:
The patent segments the detection electrode layer into multiple types of electrodes (first detection electrodes and second detection electrodes) with different capacitance characteristics. Each segment serves a specific function in the differential measurement process. This segmentation allows the system to process multiple signals simultaneously, enabling noise cancellation while maintaining a relatively simple overall structure that can be integrated into existing touch panel architectures.
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 solution effectively eliminates erroneous detection caused by external noise, ensuring accurate touch detection by equalizing the sensitivity to external noise between the detection electrodes and correcting signal levels as needed.
Implementation Method 1
A popularized touch sensor is, for example, of an electrostatic capacitance type. A touch sensor of this type catches, by a capacitive element, a change occurring in the surface electric field of a panel when a touch panel is touched with a finger or the like
Implementation Method 2
A ratio of fringe capacitance to total capacitance between one or more selected detection scan electrodes and the first detection electrode is different from a ratio of fringe capacitance to total capacitance between the one or more selected detection scan electrodes and the second detection electrode
Data Source
AI summary
A touch panel, a display panel, and a display unit achieving prevention of erroneous detection caused by external noise. The touch panel includes: a plurality of detection scan electrodes extending in a first direction and a plurality of detection electrodes facing the plurality of detection scan electrodes and extending in a second direction which intersects the first direction. The one or more selected detection scan electrodes are selected, in a desired unit, from the plurality of detection scan electrodes, to be supplied with a selection pulse, and each of the first and the second detection electrodes is selected from the plurality of detection electrodes.