Liquid Crystal Display Element Rear-Lit Mirror Light Distribution
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Solution Overview
Problem
Conventional PDLC liquid crystal panels experience a decrease in luminance in the viewing direction as they are farther from the light source due to anisotropically diffusing characteristics, leading to reduced contrast ratio and luminance in the central portion of the display screen.
Innovation Solution
A liquid crystal display element comprising a polymer-dispersed liquid crystal panel and a light source module with a mirror configured to reflect light emitted from the light source toward the liquid crystal panel, optimizing light distribution to maintain high luminance uniformity across the display screen.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If light is guided from an edge-lit backlight into the PDLC liquid crystal panel, then the display can be illuminated, but light is lost due to diffraction and scattering by TFTs and alignment films, resulting in reduced luminance in the central portion
Solution Approach 1:
The patent inverts the conventional light guide approach by placing the light source directly at the rear surface of the liquid crystal panel instead of using an edge-lit backlight. This reversal eliminates the need for light to travel through the panel from the edges, thereby preventing light loss due to diffraction and scattering by internal components like TFTs and alignment films, and achieving uniform luminance across the entire display area
Solution Approach 2:
The patent extracts and removes the light guide plate from the display structure, replacing it with a direct rear-lit configuration. By taking out the intermediate light guiding component, the system eliminates the source of light loss through diffraction and scattering, allowing light to reach the liquid crystal layer directly without passing through multiple interfaces and internal structures
2Adaptability or versatility
If PDLC is used as a light modulation layer with anisotropically diffusing characteristics, then the display can switch between transparent and scattering states, but luminance decreases in the viewing direction as distance from the light source increases
Solution Approach 1:
The patent applies local quality by positioning the light source specifically at the rear surface of the liquid crystal panel, creating a localized illumination zone that directly contacts the liquid crystal layer. This localized lighting approach ensures that light is introduced at the optimal location, allowing the PDLC to uniformly switch between transparent and scattering states across the entire panel area without the luminance degradation that occurs with edge-lit configurations
3Area of stationary object
If a light guide plate is used to distribute light across the display, then light can reach the entire panel area, but more light is lost at positions farther from the light source due to diffraction and absorption
Solution Approach 1:
The patent extracts and removes the light guide plate from the system, replacing the indirect light distribution mechanism with a direct rear-lit configuration. This elimination of the light guide plate prevents progressive light attenuation across the display area, as light now reaches all panel positions directly from the rear surface without undergoing multiple reflections, diffractions, or absorptions that would occur in a light guide plate system
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 solution effectively reduces or prevents a decrease in luminance in the scattering state, achieving higher luminance uniformity and contrast ratio across the display screen with reduced power consumption.
Implementation Method 1
a light source module with a mirror configured to reflect light emitted from the light source toward the liquid crystal panel
Implementation Method 2
voltage is applied to a liquid crystal composition sealed between paired substrates such that the alignment of liquid crystal molecules in the liquid crystal composition is changed according to the applied voltage, whereby the amount of light passing through the paired substrates is controlled
Implementation Method 3
A PDLC contains liquid crystal components dispersed in a polymer network. Application of voltage to the PDLC changes the alignment of the liquid crystal components and produces a difference in refractive index between the liquid crystal components and the polymer network
Data Source
AI summary
Provided is a liquid crystal display element capable of switching between a transparent state and a scattering state and of reducing or preventing a decrease in luminance in the scattering state. The liquid crystal display element includes a liquid crystal panel containing a polymer-dispersed liquid crystal containing a polymer network and a liquid crystal component, and a light source module including a light source adjacent to the liquid crystal panel and a mirror configured to reflect light emitted from the light source toward the liquid crystal panel.