V-Groove Light Guide Plate for Uniform LCD Backlighting
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Solution Overview
Problem
Conventional light guide plates in edge type backlight modules for LCDs suffer from non-uniform brightness due to excessive total reflections, leading to dark areas and reduced viewing angles, which hinder the achievement of high-quality, uniform illumination.
Innovation Solution
A light guide plate with a plurality of parallel V-shape grooves on its bottom surface, featuring top angles that gradually increase from one end to the other, reducing total reflections and promoting earlier light refraction for improved brightness uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If uniform V-shape grooves are formed on the light guide plate, then the light guiding structure is simple and easy to manufacture, but dark areas occur adjacent to the light input plane due to excessive total reflections
Solution Approach 1:
The patent applies local quality by varying the top angle of V-shape grooves at different positions along the light propagation direction. The grooves have smaller top angles near the light input plane and progressively larger top angles toward the light output plane. This spatial variation in groove geometry locally optimizes light extraction at each position, reducing dark areas while maintaining manufacturing feasibility through a systematic gradient pattern.
Solution Approach 2:
The patent implements parameter changes by progressively modifying the top angle parameter of the V-shape grooves along the length of the light guide plate. The top angle transitions from a smaller value near the input plane to a larger value near the output plane. This continuous parameter variation controls the light extraction efficiency at different stages, converting excessive total reflections into controlled refraction and eliminating dark areas.
2Loss of energy
If the light guide plate uses total internal reflection to guide light, then light transmission efficiency is high, but viewing angles are limited and brightness uniformity deteriorates
Solution Approach 1:
The patent applies dynamics by transitioning the light propagation mechanism from static total internal reflection to dynamic refraction-controlled extraction. The varying top angle grooves create a progressive change in light path geometry, enabling light to dynamically switch from confined total reflection modes to controlled refraction modes. This dynamic transition optimizes both transmission efficiency and brightness uniformity by managing light extraction at appropriate stages.
Solution Approach 2:
The patent ensures continuity of useful action by maintaining a continuous gradient of groove top angles throughout the light guide plate. This continuous geometric variation ensures that light extraction is progressively optimized along the entire propagation path, preventing sudden changes in light behavior and maintaining smooth, uniform brightness distribution across the display area.
3Illumination intensity
If the light guide plate is designed to extract light frequently, then dark areas are reduced, but the structure becomes more complex
Solution Approach 1:
The patent applies segmentation by dividing the light guide plate into multiple zones along the propagation direction, each with distinct groove top angle characteristics. The grooves are segmented into regions with progressively varying angles, creating distinct functional zones for light extraction. This segmentation achieves frequent, controlled extraction while maintaining structural simplicity through a systematic gradient pattern that can be manufactured as a single integrated structure.
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 significantly reduces dark areas and enhances brightness uniformity, increasing viewing angles and overall display quality by allowing lights to refract earlier into visible light, as demonstrated by a 21.75% and 63.92% brightness improvement at specific angles of view compared to conventional methods.
Implementation Method 1
Initially, the lights in the light guide plate usually travel in a total-reflections manner, following Snell's Law
Implementation Method 2
the lights continuously travel in reflection and refraction paths, wherein the refractive lights emit from a top surface 22 as visible lights
Data Source
AI summary
A light guide plate structure, for use with a back light module of a liquid crystal display, has a top surface, a bottom surface, a first end portion, a second end portion which is opposite the first end portion, and a plurality of substantially paralleled V-shape grooves formed on the bottom surface and extending from the first end portion to the second end portion. Each of said V-shape grooves comprises a top angle with a continuous variation from the first end portion to the second end portion. The present invention gets rid of the dark areas of an LCD that appear adjacent to one of the end portions in conventional models, thus enhancing the uniformity in its brightness levels.