Capping Layer Refractive Index Control for Display Color Stability
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Solution Overview
Problem
Display devices experience color temperature shifts due to light interference from sealing members with stacked film structures, leading to increased minimal perceptible color difference (MPCD), which affects image quality.
Innovation Solution
A display device design featuring a capping layer with controlled refractive indices and thicknesses, including a second capping layer with a refractive index of 1.61 to 2.3 and thickness of 30 to 60 nanometers, strategically positioned between the display element and the sealing member, to minimize color temperature movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a sealing member with stacked film structure is used, then sealing performance is improved, but light interference occurs causing color temperature shifts
Solution Approach 1:
The patent introduces a capping layer as an intermediary component between the display element and the sealing member. This capping layer has a refractive index specifically designed to be between that of the display element and the sealing member, thereby reducing light interference and minimizing color temperature shifts while preserving the sealing function of the stacked film structure.
Solution Approach 2:
The patent modifies the refractive index parameter of the capping layer to optimize optical performance. By carefully selecting and controlling the refractive index of the capping layer material, the design reduces interference effects caused by the stacked sealing films, thus maintaining color temperature stability without compromising sealing reliability.
2Temperature
If multiple capping layers with different refractive indices are arranged, then color temperature stability is improved, but device complexity increases
Solution Approach 1:
The patent applies local quality by creating a gradient structure in the capping layer, where different regions have different refractive indices. Specifically, the capping layer includes a first region with a first refractive index and a second region with a second refractive index, allowing localized optimization of optical properties to reduce interference while maintaining overall structural simplicity.
Solution Approach 2:
The capping layer is segmented into multiple regions with different refractive indices, each optimized for specific optical functions. This segmentation allows the structure to address color temperature stability through distributed optical property variations rather than requiring a completely complex multi-layer design.
3Object-affected harmful factors
If the second capping layer thickness is increased, then interference reduction is improved, but peeling risk increases
Solution Approach 1:
The patent optimizes the thickness parameter of the second capping layer to a specific range that balances optical performance and mechanical reliability. By controlling the thickness within this optimized range, the design achieves sufficient interference reduction while maintaining adequate adhesion strength to prevent peeling between layers.
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 controlled capping layer arrangement reduces the overall color temperature shift and prevents peeling issues, maintaining image quality by minimizing interference and maintaining the integrity of the display device.
Implementation Method 1
the light emitted from the display element may undergo interference due to the film thickness of the sealing member
Implementation Method 2
the second capping layer having a refractive index greater than that of the first capping layer; and a third capping layer on the second capping layer, the third capping layer having a refractive index smaller than that of the second capping layer
Data Source
AI summary
A display device includes: a substrate; a display element on the substrate; a capping layer on the display element; and a thin film encapsulation layer on the capping layer, wherein the capping layer includes: a first capping layer on the display element; a second capping layer on the first capping layer, the second capping layer having a refractive index greater than that of the first capping layer; and a third capping layer on the second capping layer, the third capping layer having a refractive index smaller than that of the second capping layer, wherein the second capping layer has a thickness of 30 nanometers (nm) to 60 nm.