Backlight Unit Truncated Cone Lens Array Oblique Light Leakage
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Solution Overview
Problem
Liquid crystal display devices face issues with increased brightness when viewed from an oblique direction during black display due to light leakage, leading to decreased image quality and contrast, as existing light collimating members either reduce front brightness or have low light extraction efficiency.
Innovation Solution
A backlight unit with a light collimating member featuring a lens array on one surface and truncated cones on another, where the truncated cones' shape and refractive indices are optimized to refract light efficiently, reducing oblique light leakage and enhancing front brightness, using a transparent substrate with a light guide plate and a light source positioned to face the side surface of the guide plate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a conventional light collimating member is used to reduce oblique light leakage, then front brightness decreases, but oblique direction brightness control improves
Solution Approach 1:
The light collimating member is segmented into multiple functional regions: a light extraction region with a first lens array for extracting light from the light guide plate, and a light collimating region with a second lens array for collimating light in the front direction. This segmentation allows each region to optimize its function independently, preventing the trade-off between front brightness and oblique light control.
Solution Approach 2:
Different regions of the light collimating member have different optical properties tailored to their specific functions. The light extraction region has lenses designed for maximum light extraction efficiency, while the light collimating region has lenses optimized for directional collimation. This local optimization ensures high front brightness without compromising oblique direction performance.
2Ease of manufacture
If a light collimating member with low contact area is used, then manufacturing complexity reduces, but light extraction efficiency decreases
Solution Approach 1:
The light collimating member extends in the thickness direction with multiple lens arrays positioned at different depths. The first lens array is positioned closer to the light guide plate for efficient light extraction, while the second lens array is positioned farther away for collimation. This dimensional arrangement allows both high light extraction efficiency and effective collimation without increasing manufacturing 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
The solution effectively suppresses brightness increase in the oblique direction while maintaining high front brightness, improving contrast and display performance by efficiently reflecting and collimating light, thus enhancing the overall image quality of liquid crystal display devices.
Implementation Method 1
a light collimating member in which a lens array is formed on one surface of a transparent substrate and a plurality of truncated cones are arranged on another surface of the transparent substrate
Implementation Method 2
a lens array is formed on one surface of a transparent substrate and a plurality of truncated cones are arranged on another surface of the transparent substrate
Implementation Method 3
an edge light mode including a light guide plate and a light source that is arranged on an edge surface (side surface) of the light guide plate, in which light incident into from the light source into the edge surface is guided and emitted from the entire main surface
Data Source
AI summary
Display performance can be improved by reducing light leak in an oblique direction at the time of black display while increasing front brightness. Provided is a backlight unit including: a light collimating member in which a lens array is formed on one surface of a transparent substrate and a plurality of truncated cones are arranged on another surface of the transparent substrate; a light guide plate; and a light source, in which the truncated cone on the light collimating member has a shape in which a width decreases away from the transparent substrate in a height direction, a position of each of lenses of the lens array deviates from a position of the truncated cone corresponding to the lens to move away from the light source in a direction that connects a center of the lens and the light source most adjacent to the lens, an optical axis of the lens is arranged to pass through a slope of the truncated cone corresponding to the lens, the light guide plate and a surface of the truncated cone opposite to the transparent substrate are in contact with each other, and the shape of the truncated cone of the light collimating member satisfies specific expressions.