Display Substrate Reflective Layer Design for Light Utilization
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Solution Overview
Problem
Conventional display apparatuses face challenges in achieving high light utilization efficiency and low power consumption, particularly due to errors in reflective layer thickness and the use of heavy metals like chrome, which are environmentally harmful and lead to pollution during the etching process.
Innovation Solution
A display substrate with a stacked structure of high and low refractive layers, where the high refractive layers are made of silicon nitride and the low refractive layers are made of silicon oxide, alternating with a metal light reflective layer to enhance reflectance and absorb light, reducing the need for heavy metals and minimizing processing errors by dividing the etching process into two steps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a high reflective layer with a stacked structure is used to achieve high reflectance, then the reflectance may be decreased according to an emitting wavelength band due to thickness errors in depositing the stacked layer
Solution Approach 1:
The high reflective layer is segmented into multiple alternating high refractive index layers and low refractive index layers, forming a distributed Bragg reflector structure. This segmentation allows the reflector to maintain high reflectance across a broader wavelength range by distributing the reflective function across multiple interfaces, reducing sensitivity to individual layer thickness variations.
Solution Approach 2:
The patent uses composite materials with alternating high and low refractive indices (such as TiO2/SiO2 or Ta2O5/SiO2) to create the stacked high reflective layer. This composite structure exploits the refractive index contrast to achieve high reflectance through constructive interference of reflected light waves, while the alternating structure provides tolerance to thickness manufacturing errors.
2Illumination intensity
If a low reflective layer is formed using chrome-based material to achieve low reflectance, then an etching chamber may be polluted due to particles generated during the etching process
Solution Approach 1:
The patent extracts and removes the problematic chrome-based material from the low reflective layer formulation. Instead, it uses alternative materials such as aluminum oxide (Al2O3), silicon nitride (Si3N4), or titanium nitride (TiN) that can achieve the desired low reflectance function without generating harmful particles during etching, thereby eliminating the pollution issue.
Solution Approach 2:
The patent employs materials that are easier to process and remove without causing chamber contamination, prioritizing process cleanliness and environmental friendliness over the use of traditional but problematic chrome-based materials. This approach aligns with industrial trends toward eliminating heavy metals from manufacturing processes.
3Illumination intensity
If the reflective layer is made relatively thick to achieve desired reflectance properties, then an error may be increased during the process of forming the opening slots
Solution Approach 1:
The thick reflective layer is segmented into multiple thin alternating layers of high and low refractive index materials. This segmentation reduces the total thickness required to achieve the same optical performance, thereby minimizing the cumulative thickness error and improving the precision of subsequent opening slot formation processes.
Solution Approach 2:
By using composite materials with alternating refractive indices, the patent achieves high reflectance with a thinner overall structure compared to a single-layer approach. This reduced total thickness decreases the margin for error in forming opening slots through the reflective layer, improving manufacturing precision.
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 increases light utilization efficiency and display quality while reducing pollution and processing errors, maintaining uniform reflectance across the visible spectrum and minimizing the use of harmful heavy metals.
Implementation Method 1
a high reflective layer, and includes a high refractive layer and a low refractive layer which alternate with each other. The high refractive layer has a first refractive index, and the low refractive layer has a second refractive index smaller than the first refractive index
Implementation Method 2
The metal light reflective layer is between the high reflective layer and the low reflective layer, and reflects light
Implementation Method 3
The low reflective layer includes a light absorbing layer which absorbs the light
Data Source
AI summary
A display substrate includes a base substrate, a high reflective layer, a metal light reflective layer and a low reflective layer. The high reflective layer is on the base substrate, and includes a high refractive layer and a low refractive layer which alternate with each other. The high refractive layer has a first refractive index, and the low refractive layer has a second refractive index smaller than the first refractive index. The metal light reflective layer is between the high reflective layer and the low reflective layer, and reflects a light. The low reflective layer comprises a light absorbing layer which absorbs a light, and at least one insulating layer. Accordingly, a light utilizing efficiency and a display quality may be increased.