LED Backlight Package With Lateral Emission for Thin Uniform LCDs
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Solution Overview
Problem
Liquid crystal displays (LCDs) face challenges with high power consumption due to the need for a constant light source in backlight units, especially in edge-lighting type configurations where local dimming is not effective. Additionally, direct-lighting type backlight units struggle with uniform light distribution and thickness due to the arrangement of light emitting diodes (LEDs) and the use of diffusion lenses.
Innovation Solution
The proposed solution involves a light emitting device with a light emitting diode chip, a light reflection member on the upper surface, a light transmitting resin covering the side surfaces, and a light blocking member on top. This configuration allows for broader light distribution through the side surfaces, reducing the need for dense LED arrangements and diffusion lenses, while enabling local dimming and improving contrast ratios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If multiple light emitting diodes are arranged in a matrix below the display panel to achieve uniform light distribution, then light uniformity is improved, but the thickness of the backlight unit increases due to the need for diffusion lenses and increased distance between light source and optical sheet
Solution Approach 1:
The patent changes the light emission direction from upward (toward the display panel) to lateral (parallel to the circuit board surface). Light emitting diodes are configured to emit light primarily in lateral directions through side surfaces, transforming the illumination geometry from vertical to horizontal dimension, thereby eliminating the need for diffusion lenses and reducing backlight unit thickness while maintaining light uniformity
Solution Approach 2:
Instead of arranging light emitting diodes to emit light upward through the display panel, the patent inverts the emission direction to emit light laterally through side surfaces. This inversion of the conventional light emission approach eliminates the need for additional optical components and reduces the overall thickness of the backlight unit
2Illumination intensity
If a diffusion lens is used to achieve uniform spreading of light emitted from light emitting diodes, then light distribution is improved, but the thickness of the backlight unit increases
Solution Approach 1:
The patent extracts and eliminates the diffusion lens component from the backlight unit by changing the light emission geometry. Light emitting diodes are configured to emit light laterally through side surfaces, which inherently provides uniform light distribution without requiring additional diffusion optical elements, thereby reducing backlight unit thickness
3Illumination intensity
If light emitting diodes are positioned spaced apart from the display panel to ensure uniform distribution, then light uniformity is improved, but the backlight unit thickness increases
Solution Approach 1:
The patent transitions the light emission approach from vertical spacing (distance between light source and display panel) to lateral emission (light traveling parallel to the circuit board surface). This dimensional change allows light to reach the display panel uniformly without requiring increased vertical spacing, thereby maintaining thin backlight unit thickness
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 effectively suppresses the spot phenomenon, enhances luminous uniformity, reduces power consumption, and allows for a thinner direct-lighting type backlight unit, while maintaining improved contrast ratios through local dimming.
Implementation Method 1
a light reflection member on an upper surface of the light emitting diode chip
Implementation Method 2
a light transmitting resin covering side surfaces of the light emitting diode chip
Implementation Method 3
a light blocking member on an upper surface of the light transmitting resin
Data Source
AI summary
A display apparatus including a display panel, and a backlight to provide light toward the display panel, the backlight including a circuit board, an optical layer disposed on the circuit board, at least one light emitter disposed between the circuit board and the optical layer and including a light emitting structure disposed on the circuit board and having first and second conductivity type semiconductor layers and an active layer therebetween, first and second electrode pads electrically connected to the first and second conductivity type semiconductor layers, respectively, a reflector on the light emitting structure, a light transmitting layer disposed on the circuit board and contacting the light emitter, and a dam disposed on the circuit board and surrounding the light emitter and including a portion having a curved shape.