Projective Capacitive Touch Panel Corner Electrode Area Reduction
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Solution Overview
Problem
Projective capacitive touch panels face challenges in maintaining detection accuracy at the edges of the detection area due to capacitive coupling issues caused by electrode configurations, leading to variations in capacitance reference values and reduced detection precision.
Innovation Solution
The touch panel design incorporates triangular end electrodes and rhombus-shaped electrodes arranged in orthogonal directions, with corner electrodes having a reduced area to minimize capacitive coupling, ensuring uniform capacitance and improved detection accuracy across the entire detection area, including the edges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If standard rhombus-shaped electrodes are used in all positions, then the electrode structure is simple and uniform, but capacitive coupling occurs at corners leading to non-uniform capacitance reference values and reduced detection accuracy
Solution Approach 1:
The patent applies local quality by making corner electrodes smaller than standard electrodes. Specifically, electrodes at corner positions (e.g., E11, E1n, Em1, Emn) have reduced dimensions compared to interior electrodes, creating position-dependent electrode characteristics that compensate for capacitive coupling effects at corners while maintaining uniform detection accuracy across the entire touch panel surface.
2Measurement precision
If electrode area is increased to improve detection sensitivity, then detection sensitivity improves, but capacitive coupling at corners increases causing non-uniform capacitance reference values
Solution Approach 1:
The patent reduces electrode area specifically at corner positions where capacitive coupling occurs, while maintaining standard electrode areas in interior positions. This localized area reduction suppresses capacitive coupling at corners without affecting detection sensitivity in the main detection area, achieving uniform capacitance reference values across all positions.
Solution Approach 2:
The patent changes the geometric parameter (area) of electrodes based on their position. Corner electrodes have smaller area parameters than interior electrodes, and this parameter modification directly addresses the capacitive coupling issue by reducing the coupled capacitance at corner positions to match the uniformity of interior positions.
3Measurement precision
If spaces with no electrode are formed at edges to simplify electrode arrangement, then electrode arrangement is simplified, but detection accuracy at edges deteriorates
Solution Approach 1:
The patent segments the electrode array into different types based on position: interior electrodes, edge electrodes, and corner electrodes. Each segment has optimized characteristics - corner electrodes are smaller to reduce coupling, while edge and interior electrodes maintain standard sizes to ensure detection accuracy. This segmentation eliminates detection dead zones at edges and corners.
Solution Approach 2:
The patent makes corner electrodes smaller than other electrodes to specifically address capacitive coupling at corner positions. This local modification ensures that corner regions remain within the detection area without creating detection dead zones, while maintaining standard electrode sizes in interior regions for optimal detection performance.
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 configuration suppresses capacitive coupling, achieves uniform capacitance reference values, and enhances detection accuracy at the edges and corners of the touch panel, improving overall detection precision.
Implementation Method 1
a voltage is applied to one of electrodes extending in X and Y directions, and the change over time in the voltage induced on another one of the electrodes is measured
Data Source
AI summary
A touch panel includes first arrays of electrodes, second arrays of electrodes, and an output part where leads extending from triangular end electrodes of the first arrays and the second arrays are connected to an external device. At least one corner electrode of the end electrodes which is located in a corner on one of four sides of the detection part where the output part is located has an area that is less than an area of other end electrodes.