Touch Sensor Transparent Electrode Segmentation for Light Transmittance
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Solution Overview
Problem
Conventional touch sensors experience reduced light transmittance and optical quality due to visible transparent electrodes and moiré patterns caused by differences in optical characteristics between electrode and inter-electrode regions, leading to visibility issues and interference with display panels.
Innovation Solution
The formation of unit transparent electrodes with fine etching patterns that convert low-frequency spatial frequencies into high-frequency components, reducing visibility and enhancing light transmittance, while preventing moiré patterns by using a tessellation structure and inter-electrode dummies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If transparent electrodes are formed in the touch sensor, then touch sensing function is achieved, but light transmittance is reduced and electrodes become visible to users
Solution Approach 1:
The transparent electrode is divided into multiple fine etching patterns (first, second, third, and fourth patterns) that are arranged in a segmented manner. This segmentation reduces the continuous coverage of the electrode material, thereby improving light transmittance while maintaining the touch sensing function through the distributed pattern structure.
Solution Approach 2:
Different regions of the transparent electrode are designed with different local qualities through varying etching patterns. The first and second patterns have different characteristics from the third and fourth patterns, allowing optimization of both sensing performance and optical properties in different local areas of the electrode.
2Reliability
If transparent electrodes are formed with regular spatial intervals, then touch sensing coverage is improved, but low-frequency spatial frequency components cause visibility issues
Solution Approach 1:
The etching patterns are designed with asymmetric characteristics where the first and second patterns differ from the third and fourth patterns. This asymmetry disrupts the regular spatial frequency components that cause visibility issues, while maintaining adequate touch sensing coverage through the distributed pattern arrangement.
Solution Approach 2:
The etching patterns incorporate curved boundaries instead of straight lines, creating circular or arc-shaped features. This curvature introduces high-frequency spatial components that mask the low-frequency visibility problems while preserving the electrode's functional coverage for touch sensing.
3Reliability
If transparent electrodes are formed to ensure channel resistance, then electrical performance is improved, but bridge patterns become visible to users
Solution Approach 1:
The bridge pattern is segmented into multiple discrete etching features rather than a continuous structure. This segmentation allows the bridge to maintain electrical connectivity for channel resistance while reducing the continuous optical path that would make it visible to users.
4Ease of manufacture
If transparent electrodes are formed with standard patterns, then manufacturing is simplified, but moiré patterns occur when bonded to display panels
Solution Approach 1:
The asymmetric arrangement of different etching patterns (first, second, third, fourth patterns with varying characteristics) disrupts the regular periodicity that causes moiré interference when the touch sensor is bonded to display panels, while still allowing for standardized manufacturing processes.
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 minimizes the visibility of transparent electrodes, increases light transmittance, and prevents optical interference patterns, thereby improving the visibility and optical quality of touch sensors when integrated with display panels.
Implementation Method 1
converting a low-frequency component of a spatial frequency induced by transparent electrodes that are repeatedly formed inside the touch sensor at regular spatial intervals into a high-frequency component that is not visible to a user by means of unit transparent electrodes distinguished by a plurality of transparent fine patterns
Implementation Method 2
transmitted light and reflected light cause an ITO pattern to be visible to users... converting a low-frequency component... into a high-frequency component that is not visible to a user... increase the light transmittance of the touch sensor
Implementation Method 3
interference may occur between a pixel array of the display panel and a pixel array of the touch sensor, and an optical interference pattern may be exhibited as a moiré pattern... preventing moiré patterns by using a tessellation structure and inter-electrode dummies
Data Source
AI summary
An improved touch sensor comprising a first sensing electrode unit formed on a substrate in a first direction and a second sensing electrode unit formed on the substrate in a second direction crossing the first direction. A plurality of fine etching patterns are formed in boundary portions of unit transparent electrodes included in the first sensing electrode unit and the second sensing electrode unit. Each unit transparent electrode may have a shape in which a portion of a curved line connecting the vertices of a polygon is removed. Adjacent unit transparent electrodes may be electrically connected to one another. The improved touch sensor prevents a transparent electrode from being visible to a user sensor and also results in the prevention of a reduction in light transmittance caused by the transparent electrode as well as the prevention a reduction in optical quality due to a moiré phenomenon.