Holographic Light Guide Plate Uniform Brightness
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Solution Overview
Problem
Conventional surface emitting devices, such as edge light type backlight units for LCDs, face challenges in achieving uniform brightness over the entire light exit surface due to varying light angles and decreased light intensity at greater distances, often resulting in hot spots near the light sources.
Innovation Solution
The surface emitting device incorporates a light guide plate with holographic patterns arranged to direct light incident at specific azimuth angles, ensuring that light emitted from the source initially reaches the patterns at a low efficiency angle and is reflected to high efficiency angles, thereby reducing hot spots and enhancing uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If light sources are located on the sidewall of the light guide plate to enable slim display design, then the device can be made compact and slim, but the amount of light decreases at distances farther away from the light sources and hot spots are formed in the light incident portion
Solution Approach 1:
The patent applies local quality by creating different surface characteristics in different regions of the light guide plate. Specifically, the light incident portion is designed with a different structure (direct light entry) compared to other portions (total internal reflection), allowing each region to optimize its light handling properties for uniform overall illumination.
Solution Approach 2:
The patent segments the light guide plate into multiple portions with different light guiding mechanisms. The light incident portion allows direct light entry while other portions use total internal reflection, creating distinct functional zones that work together to achieve uniform light distribution across the display surface.
2Speed
If holographic patterns are formed on the light exit surface to emit light perpendicularly, then light can be emitted at the desired angle, but the uniformity of light exiting varies with the angle of light entering the holographic patterns
Solution Approach 1:
The patent changes the parameters of light incident on the holographic patterns by controlling the angle at which light enters the light guide plate. By optimizing the incident angle through the segmented design, the light interacts with the holographic patterns at angles that maximize perpendicular emission while maintaining uniformity across the light exit surface.
3Illumination intensity
If separate patterns are inserted to scatter light from the light incident portion toward side surfaces, then hot spots can be reduced, but the device complexity increases
Solution Approach 1:
The patent makes the light guide plate itself multi-functional by integrating both light incident and light guiding functions into a single component. The light guide plate simultaneously serves as the structure that receives light and the medium that guides it through total internal reflection, eliminating the need for separate scattering patterns or additional components.
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 results in uniform brightness distribution across the light exit surface, reducing the occurrence of hot spots and increasing light emission efficiency, leading to improved image quality in display applications.
Implementation Method 1
The LGP 12 guides incident light thereon inside the LGP 12 by total reflection and emits the same through the top surface thereof
Implementation Method 2
The holographic patterns 14 diffract light such that the light is emitted at an angle substantially perpendicular to the top surface, i.e., the light exit surface
Data Source
AI summary
A surface emitting device and a display apparatus including the same. The surface emitting device includes: a light source; and a light guide plate having a light exit surface on which holographic patterns are formed, and guiding light emitted by the light source such that the guided light is emitted from the light exit surface, wherein the holographic patterns are arranged so that light incident on the light guide plate without passing through any side surface of the light guide plate can be incident on the holographic patterns at an azimuth greater than 45° at which light emitting efficiency is low and light incident on the light guide plate and reflected by any side surface of the light guide plate can be incident on the holographic patterns at an azimuth at which light emitting efficiency is high.