Dimming Liquid Crystal Layer for Edge Backlight Color Uniformity
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Solution Overview
Problem
Liquid crystal display devices with edge-light backlights experience color unevenness during color display and transparent display, particularly due to striated color unevenness and spot-like luminance issues, which are exacerbated by the use of field sequential drive and the absence of diffusion sheets in see-through displays.
Innovation Solution
Incorporating a dimming liquid crystal layer with adjustable haze, positioned between the edge backlight and the transmissive liquid crystal display panel, which switches between diffusion and transmission states based on voltage application, allowing for color display with the backlight on and transparent display with the backlight off, while minimizing color unevenness by optimizing the arrangement of light-emitting elements and the transparent light guide plate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If field sequential drive is used with multi-color light-emitting elements in edge backlight, then color display capability is improved, but striated color unevenness occurs in the transparent light guide plate
Solution Approach 1:
A diffusion sheet is introduced as an intermediary component between the multi-color light-emitting elements and the transparent light guide plate. This diffusion sheet scatters the light from adjacent red, green, and blue LEDs, preventing direct color mixing in the light guide plate while still enabling full-color display through field sequential drive. The diffusion sheet acts as a mediator that柔化 (softens) the light distribution to eliminate striated color unevenness.
Solution Approach 2:
The patent applies different optical properties to different regions of the light guide plate. The light guide plate has varying refractive indices or optical densities in different zones to control light propagation paths from adjacent color LEDs. This local variation in optical quality ensures uniform color distribution across the display area while maintaining the field sequential drive capability.
2Manufacturing precision
If diffusion sheet is added to cancel eyeball unevenness in white LED backlight, then luminance uniformity is improved, but transparent display capability is lost
Solution Approach 1:
The patent employs a liquid crystal layer with variable optical properties that can dynamically change between transparent and diffusing states. When a voltage is applied, the liquid crystal molecules reorient to provide transparency for see-through display mode. When no voltage is applied, they return to a scattered configuration to provide diffusion for normal display mode, thus dynamically adapting to different display requirements.
Solution Approach 2:
The liquid crystal layer serves multiple functions: it acts as a diffusion sheet when needed to cancel eyeball unevenness, and as a transparent window when transparent display is required. This multi-functional component eliminates the need for separate diffusion sheets in different display modes, enabling both high luminance uniformity and transparent display capability within a single system.
3Adaptability or versatility
If transparent light guide plate is used for see-through display, then background visibility is improved, but color unevenness and luminance issues occur
Solution Approach 1:
The diffusion sheet and liquid crystal layer serve as intermediary components between the light source and the transparent light guide plate. They control and uniformize the light distribution before it enters the transparent light guide plate, ensuring high display quality while maintaining the transparency and background visibility that the light guide plate provides.
Solution Approach 2:
The patent uses a composite structure combining transparent light guide plate material with diffusing and liquid crystal layers. This composite approach integrates the advantages of transparency from the light guide plate with the light-uniforming properties of diffusion materials and the dynamic control of liquid crystals, achieving both high display quality and transparent display capability.
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 solution effectively inhibits color unevenness and enables both color and transparent displays in liquid crystal display devices, maintaining image clarity and background visibility without the need for diffusion sheets, thereby enhancing display performance and user experience.
Implementation Method 1
a dimming liquid crystal layer that is disposed such that the dimming liquid crystal layer overlaps at least an end portion of the transparent light guide plate that faces the light-emitting elements of multiple colors in a plan view and that has a degree of haze that increases or decreases by applying a voltage
Implementation Method 2
light-emitting elements of multiple colors that are disposed such that the light-emitting elements of multiple colors are adjacent to each other and face a side surface of the transparent light guide plate
Implementation Method 3
there is a method in which the eyeball unevenness is canceled by stacking a reflective member such as a diffusion sheet on a light guide plate to cause light to scatter
Data Source
AI summary
The liquid crystal display device includes an edge backlight including a transparent light guide plate and light-emitting elements of multiple colors that are disposed such that the light-emitting elements of multiple colors are adjacent to each other, a dimming liquid crystal layer that is disposed such that the dimming liquid crystal layer overlaps at least an end portion of the transparent light guide plate that faces the light-emitting elements of multiple colors in a plan view and that has a degree of haze that increases or decreases by applying a voltage, and a transmissive liquid crystal display panel that includes pixels. With the backlight on, the dimming liquid crystal layer is in a diffusion state, and the liquid crystal display panel performs the color display. With the backlight off, the dimming liquid crystal layer is in a transmission state, and the liquid crystal display panel performs the transparent display.