LED Package Structure with Dark Adhesive for Contrast
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional LED package structures used in indoor display devices often suffer from glare phenomena due to transparent or white die-attach adhesives, leading to reduced contrast ratio and discomfort for users, especially under low ambient lighting conditions.
Innovation Solution
An LED package structure featuring a black substrate, dark-colored die-attach adhesive, black solder mask, and a dark-colored, light-transmissible encapsulant with a roughened surface to scatter incident light, enhancing contrast ratio and viewing comfort.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If transparent or white die-attach adhesive is used, then brightness is improved, but glare phenomenon occurs and contrast ratio deteriorates
Solution Approach 1:
The patent changes the color of the die-attach adhesive from transparent or white to black. This color change eliminates the glare phenomenon caused by light reflection while maintaining adequate brightness through the LED light source itself, thereby improving contrast ratio in display devices.
Solution Approach 2:
The patent converts the harmful effect of light reflection (glare) into a beneficial outcome by using black die-attach adhesive that absorbs excess light. This reduces unwanted reflections and improves the overall contrast and viewing comfort of the display device.
2Illumination intensity
If transparent or white die-attach adhesive is used, then brightness is improved, but contrast ratio deteriorates
Solution Approach 1:
The patent changes the color of the die-attach adhesive from transparent or white to black. This color change eliminates the glare phenomenon caused by light reflection while maintaining adequate brightness through the LED light source itself, thereby improving contrast ratio in display devices.
3Loss of information
If dark-colored encapsulant is used, then contrast ratio is improved, but light transmission may be reduced
Solution Approach 1:
The patent applies different optical properties to different parts of the encapsulant. The inner surface has high light extraction efficiency for brightness, while the outer surface has light scattering properties for viewing comfort and contrast enhancement. This local differentiation resolves the contradiction between light transmission and contrast ratio.
Solution Approach 2:
The patent changes the optical parameters of the encapsulant by creating a dual-layer structure with different refractive indices and surface properties. The inner layer optimizes for light extraction while the outer layer optimizes for light scattering and viewing angle, thereby maintaining light transmission while improving contrast ratio.
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 proposed LED package structure improves display contrast ratio and viewing comfort by minimizing glare and maintaining an almost dark appearance when unlit, while providing enhanced light scattering for reduced eye strain when lit.
Implementation Method 1
The dark-colored and light-transmissible encapsulant has a roughened surface to scatter incident light, thereby improving viewing comfort.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A light-emitting diode (LED) package structure (2) includes: an insulating substrate (20) that has a front bonding pad assembly (22); a dark-colored die-attach adhesive (26); blue and green LED chips (B, G) mounted on the front bonding pad assembly (22) via the dark-colored die-attach adhesive (26); and a dark-colored and light-transmissible encapsulant (21) that is disposed on the insulating substrate (20) and that encapsulates the blue and green LED chips (B, G). The encapsulant (21) has a light transmittance that ranges from 7% to 28% for the blue light and has a light transmittance that ranges from 9% to 30% for the green light.