PDLC Display Optical Layer Stack for Uniform Edge-Lit Brightness
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Display devices using polymer dispersed liquid crystals experience a decrease in brightness as the distance from the light emitting module increases, leading to degradation in display quality.
Innovation Solution
A display device configuration that includes a light guide, first and second transparent substrates, a liquid crystal layer with streaky polymer and liquid crystal molecules, a first transparent layer with a lower refractive index, and a protective layer with higher light scattering properties, which helps in suppressing brightness degradation and improving display quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a light emitting module is provided in an end portion of a display panel using polymer dispersed liquid crystals, then the display device achieves high transmittance, but brightness decreases as the distance from the light emitting module increases
Solution Approach 1:
A light guide is introduced as an intermediary component between the light emitting module and the display panel. The light guide conducts light from the light emitting module to the display panel, ensuring uniform light distribution across the entire display area. This mediator component resolves the brightness degradation issue by efficiently transmitting light over the distance from the end portion light emitting module to various points on the display panel.
Solution Approach 2:
The refractive index of the first transparent layer is specifically designed to be lower than those of the second transparent substrate and the protective layer. This parameter change in refractive index helps control light propagation and scattering characteristics, preventing light loss and maintaining brightness consistency across the display panel while allowing the light emitting module to be positioned at the end portion.
2Device complexity
If the light emitting module is positioned at the end portion of the display panel, then the device structure is simplified, but brightness uniformity deteriorates
Solution Approach 1:
The light guide serves as a mediator that connects the end portion light emitting module to the display panel, distributing light uniformly across the entire display area. This intermediary component enables the simplified end portion positioning while achieving uniform brightness distribution, resolving the contradiction between structural simplicity and brightness uniformity.
Solution Approach 2:
The first transparent layer is designed with a refractive index that is lower than the second transparent substrate and protective layer, creating specific optical properties at different locations within the device structure. This local quality differentiation in refractive indices helps control light propagation paths to achieve uniform brightness distribution despite the end portion positioning.
3Illumination intensity
If transparent layers with high refractive index are used, then light transmission is improved, but light scattering increases causing visual boundaries
Solution Approach 1:
The refractive index of the first transparent layer is deliberately set to be lower than the second transparent substrate and protective layer. This parameter change creates a refractive index gradient that reduces abrupt light scattering at interfaces while maintaining adequate light transmission. This resolves the contradiction by optimizing the refractive index parameters to balance transmission and scattering characteristics.
Solution Approach 2:
The device employs a composite structure with multiple transparent layers having different refractive indices. The first transparent layer has a lower refractive index than the second transparent substrate and protective layer, creating a composite material system that optimizes both light transmission and scattering characteristics. This composite approach allows simultaneous achievement of high transmission and reduced harmful scattering.
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 configuration effectively maintains consistent brightness and reduces visual boundaries, thereby enhancing the overall display quality by minimizing unwanted light absorption and scattering.
Implementation Method 1
display devices using polymer dispersed liquid crystals in which a scattered state for scattering incident light and a transparent state for transmitting incident light can be switched
Implementation Method 2
a protective layer provided between the light guide and the first transparent substrate, and overlapping with the aperture in plan view. The protective layer has light scattering properties higher than those of the second transparent substrate
Implementation Method 3
The first transparent layer has a refractive index smaller than refractive indices of the second transparent substrate and the protective layer
Data Source
AI summary
According to one embodiment, a display device includes a light guide, a first transparent substrate, a second transparent substrate, a liquid crystal layer, a first transparent layer, and a protective layer. The first transparent layer has a refractive index smaller than refractive indices of the second transparent substrate and the protective layer. The protective layer has light scattering properties higher than those of the second transparent substrate.