LCD Backlight LED Structure for Uniform Light and Local Dimming
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Solution Overview
Problem
Existing liquid crystal displays face issues with non-uniform light distribution, difficulty in thickness reduction, and challenges in implementing local dimming due to the use of direct-lighting type backlight units with light emitting diodes, which cause bright spots and low contrast ratios.
Innovation Solution
A backlight unit design incorporating light emitting devices with a light reflection member on the upper surface, a light blocking member, and a dam surrounding the lateral side of the light emitting diode chip, along with a distributed Bragg reflector, to ensure uniform light distribution and independent operation of each diode chip.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If multiple light emitting diodes are arranged in a matrix below the display panel to provide uniform light distribution, then light uniformity is improved, but the thickness of the backlight unit increases due to the need for dense arrangement or positioning light emitting diodes spaced apart from the display panel
Solution Approach 1:
A light guide plate is introduced as an intermediary component between the light emitting diodes and the display panel. The light guide plate receives light from the light emitting diodes and guides/distributes it uniformly across the display panel area, allowing the light emitting diodes to be positioned further from the panel while still achieving uniform illumination, thus reducing backlight unit thickness.
Solution Approach 2:
The patent transitions from direct lighting (light emitting diodes facing the display panel) to edge lighting (light emitting diodes positioned at the edge of the light guide plate). This dimensional change in light source placement allows for a thinner backlight unit structure while maintaining uniform light distribution through the light guide plate.
2Illumination intensity
If a diffusion lens is used to achieve uniform spreading of light emitted from the light emitting diodes, then light uniformity is improved, but the distance between the light source and the optical sheet must be increased, making thickness reduction difficult
Solution Approach 1:
The light guide plate serves as a mediator that replaces the diffusion lens function. Instead of using a diffusion lens that requires significant distance from the light source, the light guide plate uniformly distributes light through its structure, allowing for a more compact design with reduced thickness.
3Use of energy by stationary object
If light emitting diode chips are arranged closely to enable local dimming, then power consumption is reduced, but light from adjacent light emitting diode chips affects the region where another light emitting diode chip is placed, making it difficult to achieve a clear blackout effect
Solution Approach 1:
Light blocking members are extracted and positioned between adjacent light emitting diode chips to block stray light. This allows light emitting diodes to be arranged closely for power efficiency while preventing light from one diode from affecting adjacent regions, maintaining clear blackout effects when individual diodes are turned off.
Solution Approach 2:
The backlight unit is segmented into independent controllable regions using light blocking members. Each light emitting diode chip's light path is segmented and controlled individually, enabling precise local dimming while preventing light leakage between adjacent segments.
4Device complexity
If the region covered by one light emitting diode is increased to reduce the number of light emitting diodes, then device complexity is reduced, but it becomes disadvantageous to adopt local dimming
Solution Approach 1:
The light guide plate is divided into multiple independent light extraction regions, each corresponding to a light emitting diode chip. This segmentation allows each diode to cover a larger area through the light guide plate while maintaining independent control capability, thus supporting local dimming with fewer light emitting diodes.
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 luminous uniformity, allows for thinner designs, and supports local dimming by suppressing bright spots and improving contrast ratios in liquid crystal displays.
Implementation Method 1
a light reflection member disposed on an upper surface of the light emitting diode chip
Implementation Method 2
along with a distributed Bragg reflector
Data Source
Figure 1~3
Figure 4~5
Figure 6~9
AI summary
Disclosed is a light emitting device. The light emitting device according to an embodiment of the present invention comprises: a light emitting diode chip; a light reflection member arranged on the upper surface of the light emitting diode chip; a light transmitting resin covering at least a side surface of the light emitting diode chip; and a light blocking member covering the upper surface of the light transmitting resin.