Light Guide Plate With Variable Density Extraction Elements
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Solution Overview
Problem
Conventional edge-light type backlight devices for liquid crystal display devices suffer from luminance unevenness and interference unevenness due to inadequate light dispersion in the longitudinal direction, leading to suboptimal display quality.
Innovation Solution
The proposed lighting device incorporates a light guide plate with a reflecting member, an exit light reflection portion, and an anisotropic light collecting portion, featuring unit reflecting portions, cylindrical lenses, and flat portions strategically arranged to enhance light dispersion and reduce interference, ensuring even luminance across the display panel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the light guide plate uses a simple reflection structure on the back surface, then the device complexity is reduced, but luminance unevenness occurs in the exit light
Solution Approach 1:
The patent applies local quality by creating different regions on the back surface of the light guide plate: a first region with a reflection prevention structure (microlens array) and a second region with a reflection structure. This localized differentiation allows specific areas to control light extraction while others manage light reflection, resolving luminance unevenness without requiring complete structural redesign of the entire light guide plate.
Solution Approach 2:
The back surface is segmented into multiple functional regions: the reflection prevention structure divides light into multiple paths, while the reflection structure creates additional reflection points. This segmentation of light paths prevents concentrated light reflection and distributes luminance more evenly across the exit surface.
2Ease of manufacture
If the light guide plate uses conventional reflection processing on the back surface, then the manufacturing process is simplified, but interference unevenness occurs in the exit light
Solution Approach 1:
The patent changes the optical parameters of the back surface by introducing a microlens array with specific focal lengths and lens diameters. This transforms the reflection characteristics from simple mirror-like reflection to controlled refraction and reflection, preventing interference patterns while maintaining manufacturing feasibility through standard microlens fabrication techniques.
3Use of energy by moving object
If the light extraction elements have high density across the entire light guide plate, then light extraction efficiency is improved, but luminance unevenness and interference unevenness increase
Solution Approach 1:
The patent implements local quality by concentrating the reflection prevention structure (microlens array) in the first region where light extraction is most needed, while the second region uses reflection structure for light redirection. This localized high-density extraction approach improves overall light extraction efficiency without creating luminance unevenness across the entire plate.
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 effectively disperses light in the longitudinal direction, minimizing luminance and interference unevenness, thereby improving the overall display quality and luminance of the liquid crystal display device.
Implementation Method 1
a reflecting member arranged opposite the opposite plate surface of the light guide plate and reflecting the light
Implementation Method 2
an exit light reflection portion disposed on a side of the light exit surface of the light guide plate and reflecting light travelling within the light guide plate to accelerate exiting of the light through the light exit surface
Implementation Method 3
the plate surface-side anisotropic light collecting portion including opposite plate surface-side cylindrical lenses that extend in the first direction and are arranged in the second direction
Implementation Method 4
the light emitted by a lamp and entering the light guide plate through the light entrance surface is reflected by a reflection processing portion disposed on a back surface of the light guide plate while travelling within the light guide plate
Data Source
AI summary
A lighting device includes a light guide plate, a plurality of LEDs positioned to project light into a first side surface of the light guide plate, a reflection sheet facing a bottom surface of the light guide plate, a plurality of reflective elements on a light exit surface of the light guide plate opposite the bottom surface and extending in a direction parallel to the first side surface, and a plurality of convex elements on the bottom surface of the light guide plate. The density of the convex elements increases with increasing distance from the light source.