Touch Sensor Electrode Stacked Structure for Image Clarity
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Solution Overview
Problem
Touch sensors integrated into display devices often compromise image quality due to visually recognizable sensing electrodes, which affect both image clarity and color perception, necessitating a design that balances conductivity, sensitivity, and optical properties.
Innovation Solution
A touch sensor with a stacked structure of transparent oxide electrode layers and a metal layer, optimized through specific thickness ranges and refractive index matching, to minimize light reflection and maintain high transmittance, thereby preventing electrode visibility while ensuring conductivity and sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If sensing electrodes are arranged on the substrate layer, then touch sensing functionality is achieved, but image quality deteriorates due to visual recognition and color distortion
Solution Approach 1:
The sensing electrode uses a composite structure combining a transparent oxide electrode layer (such as ITO, IZO, or AZO) with a metal layer (such as Ag, Al, or Mo). This composite material structure enables the electrode to simultaneously provide electrical conductivity for touch sensing and optical transparency to maintain image quality, resolving the contradiction between functionality and visual appearance
Solution Approach 2:
The patent optimizes specific parameters including the thickness of each layer (transparent oxide electrode layer: 50-500 nm, metal layer: 10-200 nm), refractive index matching (transparent oxide electrode layer refractive index: 1.8-2.5), and optical ratio control (extinction coefficient/(refractive index difference) ≤ 5). These parameter adjustments enable the electrode to achieve both sufficient conductivity and high optical transparency, eliminating visual disturbance while maintaining touch sensing capability
2Reliability
If a metal layer is used for sensing electrodes, then conductivity and sensitivity are improved, but light reflection increases and transmittance decreases
Solution Approach 1:
The transparent oxide electrode layer serves as an intermediary between the metal layer and the external environment. It has high optical transparency and appropriate refractive index (1.8-2.5) that reduces light reflection at interfaces, while allowing the underlying metal layer to provide electrical conductivity. This intermediary layer effectively decouples the optical and electrical functions, enabling the metal layer to conduct electricity without causing excessive light reflection
Solution Approach 2:
The patent controls the metal layer thickness within 10-200 nm and optimizes the optical ratio (extinction coefficient/(refractive index difference)) to be 5 or less. By adjusting these parameters, the metal layer maintains sufficient electrical conductivity while minimizing light absorption and reflection, thereby reducing the harmful optical effects while preserving the beneficial electrical properties
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 effectively reduces light reflection from the sensing electrodes, enhancing image quality by maintaining high transmittance and preventing electrode visibility, while ensuring the touch sensor's functionality and durability through improved optical and mechanical properties.
Implementation Method 1
the sensing electrodes including a stacked structure of a transparent oxide electrode layer and a metal layer, and having an optical ratio of 5 or less as defined by Equation 1: Optical Ratio=extinction coefficient of the metal layer/(|a refractive index of the transparent oxide electrode layer−a refractive index of the metal layer|)
Data Source
AI summary
A touch sensor according to an embodiment of the present invention includes a substrate layer, and sensing electrodes arranged on the substrate layer. The sensing electrodes includes a stacked structure of a transparent oxide electrode layer and a metal layer, and has an optical ratio of 5 or less. A structure of high transmittance and low reflectance can be implemented by a control of the optical ratio of the sensing electrodes.