Unit reflector curved surface for LED backlight luminance uniformity
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Solution Overview
Problem
Large liquid crystal display backlights using light emitting diodes face challenges in achieving uniform luminance distribution due to unevenness in light emission.
Innovation Solution
A surface light emission apparatus with a matrix configuration of light sources, a diffusion sheet, a prism sheet, a polarization filter, and a reflector plate composed of unit reflectors with curved surfaces that focus light on or near the central axis of each light source, ensuring uniform light intensity across the emitting surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a backlight is constituted from light emitting diodes for a very large liquid crystal display panel, then wide range of color reproduction is achieved, but unevenness in luminance distribution occurs making it difficult to achieve surface light emission with uniform luminance
Solution Approach 1:
The reflector plate is divided into multiple unit reflectors, each corresponding to one light emitting diode. Each unit reflector independently controls and redirects light from its associated LED, allowing precise local adjustment of luminance distribution across the entire backlight surface.
Solution Approach 2:
Each unit reflector has a specific curved surface shape with focal points positioned to redirect light locally. The reflector plate provides different light redistribution functions at different locations, with each unit reflector tailored to compensate for luminance unevenness in its specific region while maintaining overall uniformity.
2Area of stationary object
If light emitting diodes are arranged in a matrix configuration for large size display, then display area is increased, but luminance uniformity deteriorates due to uneven light emission from multiple sources
Solution Approach 1:
The backlight system is segmented into multiple independent light source units, each with its own unit reflector. This segmentation allows individual control of light distribution from each LED, enabling uniform luminance across the large display area by adjusting each local unit's light redirection.
Solution Approach 2:
The unit reflectors act as intermediary optical elements between the light emitting diodes and the light guide plate. These intermediaries redirect and redistribute light from multiple discrete sources to create a uniform illumination pattern across the entire large area display.
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 enhances the uniformity and efficiency of light distribution, improving luminance uniformity and light utilization by redirecting and reflecting light to compensate for intensity variations, resulting in a more even and efficient light emission.
Implementation Method 1
each unit reflector has a curved surface that has a focal point located on or near the central axis of the corresponding light source along which the emitted light has the maximum intensity
Implementation Method 2
each unit reflector has a curved surface that has a focal point located on or near the central axis of the corresponding light source
Implementation Method 3
a sheet disposed opposite to the plurality of light sources so as to transmit a part of light emitted by the light sources and reflect the rest of light
Implementation Method 4
a sheet disposed opposite to the plurality of light sources so as to transmit a part of light emitted by the light sources and reflect the rest of light
Data Source
AI summary
A surface light emission apparatus for a backlight of large size that achieves surface light emission with uniform luminance is provided.The surface light emission apparatus comprises a plurality of light sources arranged in a matrix configuration, a sheet disposed opposite to the plurality of light sources so as to transmit a part of light emitted by the light sources and reflect the rest of light, and a reflector plate disposed between the adjacent light sources, wherein the reflector plate has a plurality of unit reflectors each of which is installed so as to surround one of the light sources, and each unit reflector has a curved surface that has a focal point located on or near the central axis of the corresponding light source along which the emitted light has the maximum intensity.