Backlight Unit Light Distribution via Segmented LED and Diffusion
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Solution Overview
Problem
Conventional liquid crystal display backlight units using light-emitting diodes (LEDs) face challenges in achieving uniform light distribution and color consistency, leading to image quality issues and increased power consumption.
Innovation Solution
A backlight unit design incorporating a light-emitting diode with a light-emitting layer on a transparent substrate, a first reflecting layer for light reflection, a second reflecting layer with a diffusion function, and a diffusion layer between the reflecting layers to control light distribution and reduce color unevenness, utilizing a dielectric multilayer mirror and a wavelength conversion sheet to produce white light with improved angular characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a blue light-emitting diode using a GaN semiconductor as an active layer is combined with a phosphor, then power consumption is reduced and efficiency is improved, but light distribution uniformity and color consistency deteriorate
Solution Approach 1:
The patent segments the backlight unit into multiple independent light-emitting diodes arranged in an array, with each LED acting as a separate light source. This segmentation allows for better control of light distribution through individual LED positioning and the use of diffusion plates between the LED array and liquid crystal panel, addressing the light distribution uniformity issue while maintaining the energy efficiency benefits of LED technology
Solution Approach 2:
The patent introduces diffusion plates as intermediary elements between the LED array and the liquid crystal panel. These diffusion plates scatter and redistribute the light from the LEDs, improving light distribution uniformity across the display area while preserving the low power consumption characteristics of the LED light sources
2Use of energy by moving object
If a blue light-emitting diode using a GaN semiconductor as an active layer is combined with a phosphor, then power consumption is reduced and efficiency is improved, but color consistency deteriorates
Solution Approach 1:
The patent applies local quality by using different phosphor materials with specific emission characteristics in different regions or layers. By selecting phosphors with complementary emission spectra and positioning them strategically, the system achieves better overall color consistency while maintaining the energy efficiency of the LED excitation source
Solution Approach 2:
The patent employs composite phosphor materials or multiple phosphor layers with different emission characteristics. This composite approach allows the system to achieve broader and more uniform color output across the visible spectrum, improving color consistency while the LED excitation source maintains low power consumption
3Area of stationary object
If light emitted from the chip in the front direction is diffused by refraction using a lens, then luminance on an illuminated surface near the optical axis is subdued, but an illumination distribution is made wider
Solution Approach 1:
The patent transitions from using lens-based refraction (three-dimensional optical path control) to planar diffusion plates (two-dimensional light scattering). This dimensional change allows for broader illumination distribution across the display area while maintaining more uniform luminance, avoiding the excessive broadening and optical axis luminance reduction caused by strong refraction
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 provides a cost-effective, high-efficiency backlight unit with enhanced light distribution and reduced color unevenness, improving image quality in liquid crystal display apparatus by controlling light output and maintaining consistent color across different angles.
Implementation Method 1
a light-emitting layer (34) formed of an InGaN film is formed on n-type clad layer (33), and p-type clad layer (35) formed of a p-type AlGaN film and p-type contact layer (36) formed of a p-type GaN film are formed on light-emitting layer (34) sequentially from a bottom thereof. Light-emitting layer (34) emits light by applying a voltage between n-type electrode (37) and p-type electrode (38).
Implementation Method 2
a first reflecting layer formed on a light exit side relative to the light-emitting layer and including a function of reflecting light emitted from the light-emitting layer
Implementation Method 3
Therefore, light emitted from the chip in the front direction is diffused by refraction using a lens, through a concave face near an optical axis, so that luminance on an illuminated surface near the optical axis is subdued, and an illumination distribution is made wider.
Implementation Method 4
as a light-emitting diode for a liquid crystal display apparatus, a type in which a blue light-emitting diode using a GaN semiconductor as an active layer is combined with a phosphor is becoming mainstream
Data Source
AI summary
There are provided light-emitting layer provided on transparent substrate and emitting light of a specific wavelength, mirror layer formed on a light exit side of light-emitting layer and including a function of reflecting light emitted from light-emitting layer, reflecting layer provided on a side of substrate in a manner to interpose light-emitting layer between mirror layer and reflecting layer; and a diffusion layer that diffuses light emitted from light-emitting layer is disposed between mirror layer and reflecting layer.