Touch Panel Electrode Area Balancing for Sensitivity
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Solution Overview
Problem
Capacitive touch panels suffer from uneven detection sensitivity due to differences in capacitance between X and Y electrodes, leading to varying signal-to-noise ratios, which affects overall detection sensitivity.
Innovation Solution
The solution involves reducing the area of individual electrodes on longer sides of the touch panel, setting the area ratio to be within 10% of the electrode count ratio, and incorporating floating electrodes to equalize capacitance between X and Y electrodes, ensuring equal capacitance along both directions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If individual electrodes on longer sides are made smaller to equalize capacitance, then detection sensitivity is improved, but electrode area is reduced
Solution Approach 1:
The patent applies local quality by making individual electrodes on longer sides smaller than those on shorter sides. This creates non-uniform electrode dimensions tailored to local capacitance requirements, equalizing total capacitance across all electrode lines and improving detection sensitivity uniformly across the touch panel surface.
2Measurement precision
If electrode area is increased to improve signal level, then signal-to-noise ratio improves, but ground capacitance increases leading to more noise
Solution Approach 1:
The patent changes the area parameter of individual electrodes to achieve optimal capacitance balance. By reducing electrode area on longer sides specifically, the total capacitance of each electrode line is equalized, which balances signal levels across all electrodes while preventing excessive ground capacitance that would generate noise, thus optimizing the signal-to-noise ratio.
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 enhances the signal-to-noise ratio and detection sensitivity of the touch panel, providing a more consistent and improved user input experience by minimizing noise interference from the display device.
Implementation Method 1
The touch panel described in JP 2003-511799 A detects the coordinates of a point touched by an observer through detection of a coupling capacitance between an electrode in an X direction and an electrode in a Y direction
Implementation Method 2
The plurality of X electrodes and the plurality of Y electrodes in an X-Y touch panel are formed on a substrate with an interlayer insulating film interposed between the X electrode layer and the Y electrode layer
Data Source
AI summary
A display device with a touch panel includes a display panel, and a touch panel formed above the display panel. The touch panel includes X electrodes which extend in a first direction, and Y electrodes which extend in a second direction different from the first direction. The X electrodes and the Y electrodes respectively include intersection portions each formed where the X electrodes and the Y electrodes overlap each other, and electrode portions each formed between the intersection portions, wherein the electrode portions of one of the X electrodes is smaller in area than the electrode portions of one of the Y electrodes, and wherein floating electrodes are formed close to the electrode portion of the one of the X electrodes or Y electrodes, and over a reduced portion of the X electrode.