Transparent Touch Switch with Refractive Index Matching
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Solution Overview
Problem
Existing transparent touch switches, such as electrostatic capacitive touch switches, suffer from reduced visibility due to the conspicuous pattern of the transparent conductive film, which affects their integration with devices like liquid crystal displays.
Innovation Solution
A transparent planar body with a patterned transparent conductive film and a transmittance-adjusting layer that equalizes the light transmission spectrum between patterned and non-patterned regions, using an overcoat layer with a lower refractive index than the conductive film and an adhesive layer with a refractive index less than the conductive film, along with a quarter-wave plate configuration, to minimize the visibility of the conductive film patterns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a transparent conductive film is patterned to enable touch detection, then the touch switch functionality is achieved, but the pattern becomes conspicuous and visibility is reduced
Solution Approach 1:
An undercoat layer with intermediate refractive index (1.7-1.9) is introduced between the transparent substrate (refractive index 1.5) and the transparent conductive film (refractive index 2.0-2.3). This intermediary layer creates a gradual refractive index transition, reducing the optical contrast that makes the conductive film pattern conspicuous, while preserving the touch detection functionality of the conductive film.
Solution Approach 2:
The refractive index parameter of the layer between the substrate and conductive film is specifically optimized to fall within 1.7-1.9. By controlling this parameter, the optical visibility of the conductive film pattern is reduced while maintaining its electrical functionality for touch detection. The thickness of this undercoat layer is also controlled at 50-150 nm to achieve the desired optical effect.
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
The solution enhances visibility by making the conductive film patterns inconspicuous, improving the aesthetic integration of the touch switch with display devices while maintaining detection capabilities.
Implementation Method 1
the overcoat layer be thicker than the transparent conductive film and have a lower refractive index than the transparent conductive film... the difference in refractive index between the transparent conductive film and the overcoat layer be 0.03 to 0.4
Data Source
AI summary
The present invention provides a transparent planar body and a transparent touch switch that can improve visibility. Specifically, the transparent planar body (1) has a patterned transparent conductive film (12) on at least one surface of a transparent substrate (11). This transparent planar body (1) comprises a transmittance-adjusting layer for equalizing the transmission spectrum of light transmitted through a patterned region wherein the transparent conductive film (12) is provided via the transparent substrate (11) with that transmitted through a non-patterned region wherein the transparent conductive film (12) is not provided via the transparent substrate (11).