Edge-Light Light Guide Plate with Arcuate Convex-Concave Surfaces
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Solution Overview
Problem
Conventional light guide plates used in edge-light type backlight units for liquid crystal display devices suffer from luminance unevenness due to directivity imparted by reflecting means, requiring additional diffuser sheets and resulting in increased thickness and manufacturing costs, which complicates the production of light guide plates of varying thicknesses.
Innovation Solution
An edge-light type light guide plate with parallel elongated convex and concave surfaces of arcuate cross-sections, where the convex surfaces on one surface and concave surfaces on the opposing surface guide light internally and diffuse it uniformly, allowing for thinner designs and reduced manufacturing complexity through press forming processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If conventional reflecting means (sawtooth-shaped prisms) are used in light guide plates, then light guidance toward the inner part is improved, but luminance uniformity deteriorates due to directivity
Solution Approach 1:
The patent inverts the conventional approach by placing convex surfaces on the light exit surface instead of concave reflecting surfaces. This inversion eliminates the directivity problem while maintaining light guidance efficiency through the complementary concave surfaces on the opposite side.
Solution Approach 2:
The patent applies different surface geometries to different locations: convex surfaces on the light exit surface for uniform light diffusion, and concave surfaces on the opposite surface for effective light reflection and guidance. This local differentiation resolves the contradiction between light guidance and luminance uniformity.
2Manufacturing precision
If additional diffuser sheets are added to eliminate luminance unevenness, then luminance uniformity is improved, but device thickness increases
Solution Approach 1:
The patent merges the light diffusion function into the light guide plate itself through convex surfaces, eliminating the need for separate diffuser sheets. This integration achieves both luminance uniformity and thin profile by combining multiple functions into a single component.
Solution Approach 2:
The light guide plate becomes multi-functional by incorporating both light guidance (through concave surfaces) and light diffusion (through convex surfaces) functions. This universal design eliminates the need for additional specialized components, reducing overall thickness.
3Adaptability or versatility
If injection molding is used to produce light guide plates of different thicknesses, then manufacturing flexibility is improved, but manufacturing cost increases due to multiple molds
Solution Approach 1:
The patent changes the manufacturing approach from injection molding to press forming, which allows thickness to be easily adjusted by changing the press forming tooling rather than requiring completely different molds. This parameter change enables cost-effective production of various thicknesses.
Solution Approach 2:
The patent replaces the injection molding process with a press forming process. This substitution simplifies the manufacturing system for producing light guide plates of different thicknesses, as press forming requires less complex tooling and can more easily accommodate thickness variations without requiring multiple specialized molds.
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 design minimizes luminance unevenness and allows for the production of thinner light guide plates with improved uniformity and reduced manufacturing costs, enabling efficient mass production and adaptation for various product sizes with a single set of forming dies.
Implementation Method 1
Light emitted from the light-emitting surfaces 3a of the LEDs 3 enters the light guide plate 6 through the side edge surface 6c and travels through the light guide plate 6. While doing so, the light properly exits the first surface (upper surface) 6a of the light guide plate 6 under the action of the reflective sheet 27.
Implementation Method 2
Light emitted from the light-emitting surfaces 3a of the LEDs 3 enters the light guide plate 6 through the side edge surface 6c and travels through the light guide plate 6. While doing so, the light properly exits the first surface (upper surface) 6a of the light guide plate 6 under the action of the reflective sheet 27.
Data Source
AI summary
An edge-light type light guide plate 30 is provided and has a first surface 31 and a second surface 32 that are opposed to each other, and a peripheral edge surface extending between the peripheral edges of the first and second surfaces. A part of the peripheral edge surface is defined as a light entrance plane 30a. The first surface 31 has a series of parallel elongated convex surfaces 31a that have an arcuate cross-section and extend in a direction substantially perpendicularly intersecting the light entrance plane 30a. The second surface 32 has a series of parallel elongated concave surfaces 32a that have an arcuate cross-section and extend in a direction substantially perpendicularly intersecting the elongated convex surfaces 31a on the first surface.