LCD Backlight Optics for Luminance Uniformity and Local Dimming
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Solution Overview
Problem
Existing liquid crystal displays using high-directivity light sources like LEDs suffer from issues with luminance uniformity, which leads to ineffective control of the light sources, resulting in reduced luminance and luminance uniformity, impacting the effectiveness of local dimming control.
Innovation Solution
A liquid crystal display design incorporating a backlight with a substrate, lens member, and diffuser plate, where the lens member anisotropically diffuses light and the diffuser plate enhances luminance uniformity by controlling the distance between the lens member and diffuser plate, combined with reflectors to manage light distribution and local dimming control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If high-directivity light sources like LEDs are used in the backlight, then luminance can be increased, but luminance uniformity deteriorates
Solution Approach 1:
The patent introduces a light guide plate as an intermediary component between the LED light sources and the display panel. This light guide plate diffuses the high-directivity light from LEDs to achieve uniform luminance distribution across the display area, resolving the contradiction between high luminance and luminance uniformity
Solution Approach 2:
The patent optimizes the distance parameter between the lens member and diffuser plate (0 to 72 mm) to control light distribution characteristics. By adjusting this distance parameter, the system achieves both high luminance and uniform luminance distribution simultaneously
2Illumination intensity
If local dimming control is implemented, then display contrast can be improved, but luminance uniformity control becomes difficult
Solution Approach 1:
The patent divides the backlight into multiple independently controllable light emitter regions. This segmentation enables local dimming control where different zones can be adjusted independently to improve display contrast while maintaining overall luminance uniformity through coordinated control of each segment
Solution Approach 2:
The light guide plate serves as a mediator that distributes light from segmented LED regions uniformly across the display area. This allows local dimming control to be implemented while preventing visible non-uniformity, as the light guide plate blends the light from different controlled zones
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 achieves higher luminance and luminance uniformity, enabling effective local dimming control and improved display performance, particularly in virtual image display devices like head-up displays.
Implementation Method 1
The lens member is configured to anisotropically diffuse light emitted from the backlight
Implementation Method 2
The diffuser plate is configured to diffuse the light emitted from the lens member
Data Source
Figure 1~2
Figure 3~4
Figure 5~6A
AI summary
A liquid crystal display includes a backlight, a lens member, a diffuser plate, and a liquid crystal panel. The backlight includes a substrate including a first surface and a plurality of light emitters located on the first surface. The lens member is configured to anisotropically diffuse light emitted from the backlight. The diffuser plate is configured to diffuse the light emitted from the lens member. The liquid crystal panel is configured to receive the light emitted from the diffuser plate. The lens member and the diffuser plate are at a distance of 0 to 72 mm inclusive.