Capacitive Touch Panel Electrode Layout for Narrow-Bezel Edge Accuracy
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Solution Overview
Problem
Electrostatic capacitive touch-sensitive panels with narrow bezels face challenges in maintaining touch accuracy on edge regions due to increased time constants and reduced extension portions of touch electrode lines, leading to low accuracy.
Innovation Solution
The design includes a touch electrode forming area with asymmetrical outermost second touch electrode patterns and zigzag portions, maximizing signal strength at sensing nodes on the edge regions by increasing electrostatic capacitance channels, and using insulation patterns to prevent overlap between touch electrode lines.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If the bezel width is reduced to achieve a narrow bezel design, then the device appearance is improved and screen-to-body ratio is increased, but touch accuracy on edge regions deteriorates due to increased time constants and reduced extension portions of touch electrode lines
Solution Approach 1:
The outermost second touch electrode pattern is designed with an asymmetrical shape, specifically extending further in the first direction (horizontal) than in the second direction (vertical). This asymmetry compensates for the reduced extension portions caused by narrow bezel design, maximizing signal strength at edge sensing nodes while maintaining the narrow bezel appearance.
Solution Approach 2:
The touch electrode patterns are designed with different shapes and extension lengths at different locations. Specifically, the outermost patterns at edge regions have extended portions with larger extension lengths compared to inner patterns, creating local variations in electrode geometry to optimize signal strength at edge sensing nodes while maintaining uniform performance across the display area.
2Device complexity
If the extension portions of touch electrode lines are reduced to accommodate narrow bezel design, then the device structure is simplified, but signal strength at sensing nodes deteriorates leading to low touch accuracy
Solution Approach 1:
The outermost second touch electrode pattern incorporates an asymmetrical design where the extension length in the first direction (horizontal) is greater than in the second direction (vertical). This asymmetry is specifically configured to maximize signal strength at edge sensing nodes, compensating for the overall reduced extension portions while maintaining structural simplicity for narrow bezel design.
Solution Approach 2:
The extension length parameter of the touch electrode patterns is optimized, with the outermost patterns having larger extension lengths (e.g., 50-150 micrometers) compared to inner patterns. This parameter variation ensures sufficient signal strength at edge regions while accommodating the narrow bezel structural constraints.
3Duration of action of moving object
If the time constant is increased in narrow bezel design, then the electrode line capacitance is reduced, but touch signal detection capability deteriorates leading to low edge region accuracy
Solution Approach 1:
The asymmetrical design of the outermost second touch electrode pattern creates localized capacitance optimization at edge regions. By extending the electrode pattern further in the first direction, the design compensates for the overall reduced capacitance in narrow bezel configurations, maintaining sufficient signal strength for accurate touch detection at edge sensing nodes despite the increased time constant.
Solution Approach 2:
The touch electrode structure implements local quality variations where outermost patterns have different geometries and larger extension lengths compared to inner patterns. This local optimization ensures that edge region sensing nodes receive adequate signal strength even when the overall time constant is increased due to narrow bezel design constraints.
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 enhances touch accuracy on edge regions by maximizing signal strength and minimizing capacitance differences, effectively addressing the limitations of narrow bezel designs.
Implementation Method 1
The electrostatic capacitive touch-sensitive panel senses a touched position based on changes in voltage generated in an upper plate or a lower plate when the user touches an equipotential conductive film formed on the upper or lower plate
Implementation Method 2
In the mutual-capacitance touch-sensitive panel, x-axis electrode lines or serials (e.g., touch driving electrode lines or serials) and y-axis electrode lines or serials (e.g., sensing electrode lines or serials) intersect each other to form a matrix in a touch electrode forming area of the touch-sensitive panel, a driving pulse is applied to the X-axis electrode lines, and changes in voltage appearing at sensing nodes defined by the crossing points between the X-axis electrode lines and the Y-axis electrode lines are sensed through the Y-axis electrode lines to determine the presence or absence of a touch
Data Source
AI summary
An electrostatic capacitive touch-sensitive panel has an active area; a touch electrode forming area; a routing wire forming area disposed; a plurality of first touch electrode lines disposed in the active area, with both ends extending to a plurality of electrode pattern extension regions; a plurality of second touch electrode lines disposed in the active area to cross the first direction so as to cross the first touch electrode lines without contact; a plurality of first routing wires connected to the plurality of first touch electrode lines, respectively; and a plurality of second routing wires connected to the plurality of second touch electrode lines, respectively. Each of the second touch electrode lines includes a plurality of second touch electrode patterns and a plurality of second connecting portions connecting neighboring second touch electrode patterns. The second touch electrode pattern has an asymmetrical portion.