LED Backlight Optical Path Extension for Display Brightness Uniformity
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Solution Overview
Problem
Display devices face challenges in achieving uniform brightness and maintaining a slim thickness due to limitations in light distribution and optical path optimization.
Innovation Solution
The solution involves a display device design where LED light sources are placed on the lower surface of a substrate, connected to a light source driving electrode, and emit light to a reflection plate, which increases the optical distance and diffuses the light effectively, improving brightness uniformity. This design includes an in-cell reflective polarizing plate with wire grid patterns and a diffusion plate to enhance light distribution, and a diffusion member on the light source driving electrode to further scatter light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If LED light sources are placed on the lower surface of the substrate to increase optical distance, then brightness uniformity is improved, but device thickness increases
Solution Approach 1:
The patent places LED light sources on the lower surface of the substrate rather than the conventional upper surface, utilizing the z-dimension (vertical direction) to extend the optical path length. This dimensional repositioning allows light to travel a longer distance through the liquid crystal layer, improving brightness uniformity without requiring additional horizontal space that would increase device footprint.
Solution Approach 2:
The patent introduces a reflection plate positioned below the lower surface of the substrate to reflect light back upward through the liquid crystal layer. This intermediary component effectively doubles the optical path length, allowing light to traverse the liquid crystal layer twice (downward and upward), thereby enhancing brightness uniformity while maintaining a compact device structure.
2Illumination intensity
If diffusion plates and diffusion members are added to scatter light, then brightness uniformity is improved, but device complexity increases
Solution Approach 1:
The patent combines multiple light diffusion functions into a single integrated diffusion plate positioned between the lower surface of the substrate and the reflection plate. This merged component performs both diffusion and reflection functions, reducing the total number of separate optical components while maintaining brightness uniformity.
Solution Approach 2:
The diffusion plate is designed to serve multiple functions simultaneously: it diffuses light from the LED sources, positions the light before reflection, and works in conjunction with the reflection plate to create the extended optical path. This multi-functionality reduces the need for separate dedicated components for each function.
3Illumination intensity
If in-cell reflective polarizing plate with wire grid patterns is used, then optical characteristics are improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent specifies particular parameter ranges for the wire grid patterns, including wire width of 1-5 μm, spacing of 5-10 μm, and grid orientation at 45 degrees to the substrate normal. By defining these specific parameter ranges, the patent balances optical performance requirements with manufacturability, allowing standard manufacturing processes to achieve the desired precision without excessive 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
This configuration enhances brightness uniformity and allows for a slim display device by increasing the optical distance of light travel, effectively diffusing and reflecting light to achieve better illumination and a reduced component count, thereby reducing manufacturing costs.
Implementation Method 1
a reflection plate disposed under the display panel, and a light emitting diode ("LED") light source disposed on the lower surface of the lower base substrate, connected to the light source driving electrode, and emitting a light to the reflection plate
Implementation Method 2
a diffusion plate disposed between the display panel and the reflection plate. a diffusion member disposed on a lower surface of the light source driving electrode
Implementation Method 3
the lower substrate further may include an in-cell reflective polarizing plate disposed on the lower base substrate and including a plurality of wire grid patterns
Data Source
AI summary
A display device includes a display panel, a reflection plate, and a light emitting diode light source, the display panel including a lower substrate including a lower base substrate, a liquid crystal layer disposed on the lower substrate, and a light source driving electrode disposed on a lower surface of the lower base substrate where the reflection plate is disposed under the display panel, and the light emitting diode light source is disposed on the lower surface of the lower base substrate, connected to the light source driving electrode, and emits a light to the reflection plate.