Edge-Lit LCD Backlight With Optical Dome for Hot Spot Reduction
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Solution Overview
Problem
Edge-type backlight units using LEDs as light sources suffer from hot spots due to the narrow light emission angle of point light sources, requiring excessive LED placement, which affects uniformity and efficiency.
Innovation Solution
Incorporation of an optical dome that completely covers the LED, dispersing light emission and reducing the number of LEDs needed, while using a chip-on-board process to attach LEDs directly to the printed circuit board, enhancing thermal stability and energy efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If multiple LEDs are arranged on the printed circuit board to prevent hot spots, then light uniformity is improved, but device complexity and energy consumption increase
Solution Approach 1:
An optical dome is introduced as an intermediary component between the LED and the liquid crystal panel. The optical dome diffuses and redirects light from the LED, acting as a mediator that improves light uniformity without requiring multiple LEDs. This resolves the contradiction by providing a simpler solution (single LED + optical dome) that achieves the same light uniformity as multiple LEDs would provide.
Solution Approach 2:
The optical dome changes the light emission parameters by modifying the light's directionality and distribution pattern. By altering the light's propagation characteristics through refraction and diffusion, the system achieves improved uniformity with fewer light sources, thereby reducing device complexity.
2Illumination intensity
If multiple LEDs are arranged on the printed circuit board to prevent hot spots, then light uniformity is improved, but energy consumption increases
Solution Approach 1:
The optical dome serves as a light-guiding intermediary that efficiently directs light from a single LED to the liquid crystal panel, improving light utilization efficiency. This reduces energy waste and the total energy consumption required to achieve uniform illumination, eliminating the need to power multiple LEDs.
3Device complexity
If LEDs are used as point light sources, then device complexity is reduced, but hot spots occur due to narrow light emission angle
Solution Approach 1:
The optical dome is designed with a curved surface that redirects light rays from the point-source LED in multiple directions. This curvature transforms the narrow, directional light emission into a broader, more uniform light distribution pattern, eliminating hot spots while maintaining the simplicity of using a single LED.
Solution Approach 2:
The optical dome acts as a light-modifying intermediary that bridges the gap between the point-source LED and the liquid crystal panel. It diffuses and redistributes the light, converting the harsh point-source emission into a softer, more uniform illumination without requiring multiple light sources.
4Illumination intensity
If more LEDs are used to eliminate hot spots, then light uniformity is improved, but manufacturing complexity increases
Solution Approach 1:
By introducing the optical dome as a single integrated component, the manufacturing process is simplified compared to assembling and positioning multiple LEDs. The optical dome can be manufactured as one piece and installed in a single step, reducing assembly complexity while achieving the same light uniformity improvement.
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 effectively reduces hot spots and improves light uniformity, achieving higher energy efficiency and thermal stability in display apparatuses.
Implementation Method 1
an optical dome completely covering the light-emitting diode
Implementation Method 2
optical dome configured to diffuse light
Implementation Method 3
a light guide plate on a second side of the liquid crystal panel opposite to the first side of the liquid crystal panel
Implementation Method 4
a light-emitting diode attached to a printed circuit board
Data Source
AI summary
A display apparatus includes a liquid crystal panel configured to display an image in a first direction at a first side of liquid crystal panel; a light guide plate on a second side of the liquid crystal panel opposite to the first side of the liquid crystal panel; a light source module facing a thickness side surface of the light guide plate to and configured emit light toward the thickness side surface of the light guide plate, the light source module including a plurality of light sources arranged along a second direction orthogonal to the first direction, wherein each light source of the plurality of light sources includes: a light-emitting diode attached to a printed circuit board, and an optical dome completely covering the light-emitting diode.