Surface-Mount Multi-Color LED Package for High-Contrast Light Extraction
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Solution Overview
Problem
Conventional light emitting devices, such as SMD types, face challenges in efficient light extraction and mounting costs due to their design, which can lead to reduced display contrast and increased manufacturing steps.
Innovation Solution
A multi-color light emitting device with a package for surface mounting, featuring leads with recesses and a dark-colored resin, and a mold resin with colored lens portions that match the light emission colors of the elements, allowing for efficient light extraction and reduced reflection, enabling surface mounting by reflow soldering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a lamp type light emitting device is used, then light extraction efficiency in frontward direction is improved, but mounting cost and manufacturing complexity increase
Solution Approach 1:
The light emitting device is divided into separate functional components: the LED chip mounted on a lead frame, and the resin package with lens portions. This segmentation allows the device to be surface-mounted as a complete unit using reflow soldering, eliminating the need for separate complex mounting procedures while maintaining efficient light extraction through the optimized resin package structure.
Solution Approach 2:
The patent combines the LED chip, lead frame, and resin package with lens portions into a single surface-mountable unit. This merging allows the device to be mounted directly onto circuit boards using standard reflow soldering processes, reducing mounting complexity while the integrated resin package structure maintains efficient light extraction in the frontward direction.
2Ease of manufacture
If conventional SMD type light emitting device is used, then mounting cost is reduced, but light extraction efficiency and display contrast deteriorate
Solution Approach 1:
The resin package incorporates lens portions with specific optical properties localized at the light extraction regions. These lens portions are designed with specific shapes and colors to optimize light extraction efficiency and display contrast in critical areas, while the overall package structure maintains compatibility with low-cost surface mounting processes.
3Object-affected harmful factors
If dark-colored resin is used, then reflection is reduced and display contrast is improved, but light extraction efficiency may be affected
Solution Approach 1:
The patent uses dark-colored resin for the base portion to reduce reflection and improve display contrast, while incorporating transparent or light-colored lens portions in specific regions to maintain efficient light extraction. The lens portions are strategically positioned and colored to allow maximum light transmission in the frontward direction while the dark resin provides contrast enhancement in other areas.
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 device achieves high light extraction efficiency in the frontward direction, reduces mounting costs, and enhances display contrast by minimizing reflection and improving luminance while extending operational life with reduced driving power.
Implementation Method 1
a plurality of light emitting elements including a first light emitting element disposed in the first recess and configured to emit first light, a second light emitting element disposed in the second recess and configured to emit second light having a wavelength shorter than a wavelength of the first light
Implementation Method 2
Each of the plurality of lens portions has a convex shape protruding upwardly from the base portion. In a plan view, the plurality of lens portions include a first lens portion overlapping with the first recess and the first light emitting element
Implementation Method 3
The first lens portion is colored in a similar color as the first light, the second lens portion is colored in a similar color as the second light, and the third lens portion is colored in a similar color as the third light
Implementation Method 4
a dark-colored resin securing at least some of the plurality of leads
Data Source
AI summary
A light emitting device includes a package for surface mounting including a plurality of leads, three leads of the plurality of leads respectively including an exposed region exposed from the dark-colored resin at a primary surface of the package, with first to third recesses each defined in the exposed region of a respective one of the three leads; first to third light emitting elements configured to emit first to third light, respectively; and a mold resin including first to third lens portions overlapping with the first to third recesses and the first to third light emitting elements, respectively, in a plan view, and colored in a similar color as the first to third light, respectively.