Light Guide Plate Dot Whiteness for LCD Backlight
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Solution Overview
Problem
Existing backlight technologies face challenges in achieving super low-profiling and large-sized light guide plates for liquid crystal displays, particularly in preventing dots-visualization and maintaining image quality, as conventional methods struggle to scale up while maintaining thickness and luminance efficiency.
Innovation Solution
The proposed solution involves a light guide plate with a pair of principal surfaces and side surfaces, where at least one light source is opposed to a side surface, a diffusing sheet on one principal surface, and a reflecting sheet on the other, with light diffusing dots on the lower surface that satisfy specific whiteness and coverage relationships to optimize light distribution and reduce dots-visualization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the light guide plate is enlarged to large size (32-inch diagonal, about 720 mm length), then the screen size is increased, but the thickness becomes difficult to maintain at 3 mm or less due to the increased length/thickness ratio
Solution Approach 1:
The patent applies local quality by differentiating the dot characteristics in different regions of the light guide plate. Specifically, dots in the light source adjacent area have controlled whiteness to prevent visualization, while dots in other areas can have different properties. This regional differentiation allows the light guide plate to maintain thinness (3 mm or less) across the entire large area (720 mm length) without compromising image quality or causing dot visualization artifacts.
2Loss of energy
If the printed dots are down-sized to reduce light extraction in the light source adjacent area, then the light extraction ratio is reduced, but the dots become visualized on the screen and the coverage of the principal surface is significantly dropped
Solution Approach 1:
The patent applies parameter changes by controlling the whiteness parameter of dots in the light source adjacent area. Instead of simply changing dot size, the invention adjusts the whiteness parameter to satisfy specific mathematical relationships, which prevents dot visualization while maintaining appropriate light extraction ratios. This parameter-based control allows dots to remain invisible on screen while achieving the desired light extraction performance.
Solution Approach 2:
The patent differentiates dot properties between the light source adjacent area and other areas of the light guide plate. In the light source adjacent area, dots have controlled whiteness to prevent visualization, while in other areas, dots can have different characteristics. This local quality approach allows optimal light extraction in different regions without causing dot visualization artifacts.
3Object-affected harmful factors
If machine-worked dots with small diameter (0.02 through 0.1 mm) are used, then dots-visualization is reduced, but it becomes extremely difficult to manufacture the metal mold for large screen light guide plates
Solution Approach 1:
The patent changes the approach from controlling dot diameter to controlling dot whiteness. By using printed dots with controlled whiteness parameters rather than machine-worked dots, the invention eliminates the need for complex metal mold manufacturing while preventing dot visualization. This parameter-based control method is much easier to manufacture for large screen light guide plates.
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 allows for the achievement of large-sized and super low-profile light guide plates, preventing dots-visualization and enhancing image quality by optimizing light distribution and maintaining high luminance, thus improving display quality and contrast.
Implementation Method 1
a light diffusing dot adapted to diffuse light, which is input from the light source to the light guide plate, towards the respective principal surfaces of the light guide plate
Implementation Method 2
a reflecting sheet disposed so as to be opposed to the other of the principal surfaces of the light guide plate
Implementation Method 3
a diffusing sheet disposed so as to be opposed to one of the principal surfaces of the light guide plate
Data Source
AI summary
In a liquid crystal display equipped with a side edge backlight device, visualization of “a dot provided to a light guide plate” in the vicinity of the light source while keeping the luminance of the display screen. The shapes and the arrangement of the light diffusing dots (dots) provided to the principal surface of the light guide plate of the backlight device are made different between the area of the principal surface in the vicinity of the light source and the other areas, thereby adjusting the whiteness of the light guide plate in the vicinity of the light source. The plurality of dots formed in the vicinity of the light source are each composed of a first section for diffusing the light propagating the light guide plate, and a second section surrounded by the first section and less capable of diffusing the light, and are disposed in the vicinity of the light source in a zigzag manner.