Layered Touch Sensor Electrodes for Low Resistance and High Transmission
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Solution Overview
Problem
Conventional single-glass typed capacitive touch sensors face challenges in reducing sheet resistance and enhancing light transmission, as they rely on indium tin oxide (ITO) for electrode layers and silicon dioxide for insulation, which limits their electrical and optical performance.
Innovation Solution
A touch sensor structure utilizing a substrate with alternating layers of insulated metal oxide as buffer layers and doped metal oxide as electrode layers, where zinc oxide (ZnO) and gallium doped zinc oxide (GZO) are used, reducing sheet resistance and improving electrical properties while maintaining similar optical properties through minimal refractive index differences between layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ITO layer is directly formed on glass substrate by sputtering, then the touch sensing electrode layer can be formed, but the sheet resistance is high and light transmission is limited
Solution Approach 1:
The patent divides the electrode structure into multiple segments: a first ITO layer formed on the glass substrate, and a second ITO layer formed on the first ITO layer. This segmentation allows each layer to contribute differently to the overall performance, with the first layer providing adhesion and the second layer providing low resistance and high transparency, thus resolving the contradiction between electrical performance and light transmission.
Solution Approach 2:
The patent uses a composite structure of multiple ITO layers with different properties. The first ITO layer has higher resistance and serves as an adhesion layer, while the second ITO layer has lower resistance and provides the primary conductive function with high transparency. This composite material approach allows the system to achieve both low sheet resistance and high light transmission simultaneously.
2Illumination intensity
If conventional single-glass typed capacitive touch sensor structure is used, then the fabrication process is established, but additional optical matching layers are needed to improve light transmission
Solution Approach 1:
The patent makes the ITO layers serve multiple functions: they provide electrical conductivity for touch sensing, act as adhesion layers to the glass substrate, and function as optical matching layers due to their refractive index properties. This multi-functionality eliminates the need for separate optical matching layers, reducing device complexity while improving light transmission.
Solution Approach 2:
The ITO layers in the patent serve themselves by providing both electrical and optical functions. The inherent optical properties of the ITO material allow it to act as an optical matching layer without requiring additional specialized layers, thus the structure is self-sufficient and reduces overall device complexity.
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 proposed structure significantly reduces sheet resistance and enhances light transmission to about 89% without the need for additional optical matching layers, improving the overall electrical and optical performance of the touch sensor.
Implementation Method 1
An ITO layer is directly formed on a glass substrate by sputtering
Data Source
AI summary
A touch sensor is provided. The touch sensor includes a first buffer layer disposed on a substrate, a first electrode layer disposed on the first buffer layer, a second buffer layer disposed on the first electrode layer and a second electrode layer disposed on the second buffer layer and electrically connected with the first electrode layer, wherein the first and second buffer layers are formed of the same material including an insulated metal oxide, and the first and second electrode layers are formed of the same material including a doped metal oxide.