Backlight LED Array with Inner Green and Outer Blue Elements
Solution Overview
Problem
Light emitting devices using LEDs often suffer from color non-uniformity due to the intense, straight-line travel of light emitted from phosphor-less elements, which affects their color reproducibility and uniformity in applications like liquid crystal display backlights.
Innovation Solution
The use of at least three light emitting elements arranged side by side, with two outer elements emitting blue light and an inner element emitting green light, connected in series, and covered by a light transmissive member containing a phosphor that converts blue light to red light, reducing color non-uniformity by enhancing light mixing and emission uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If light emitting elements are used without phosphor, then light emission efficiency is improved, but color non-uniformity increases
Solution Approach 1:
The patent applies local quality by differentiating the functions of outer and inner light emitting elements. Outer elements emit blue light to excite phosphor, while the inner element emits green light directly. This spatial differentiation of emission characteristics resolves the contradiction by localizing phosphor excitation to outer regions while maintaining color uniformity through central green emission.
Solution Approach 2:
The patent uses a composite light emission system combining phosphor-converted blue light from outer elements and direct green light from the inner element. This composite approach creates a balanced spectral distribution that maintains both high efficiency and color uniformity, resolving the technical contradiction between efficiency and color stability.
2Manufacturing precision
If phosphor is added to convert blue light to red, then color reproducibility is improved, but light intensity loss increases
Solution Approach 1:
The patent localizes phosphor usage to outer light emitting elements only, where it converts blue light to red for improved color reproducibility. The inner element emits green light directly without phosphor, avoiding energy loss and maintaining high light intensity in the central region.
Solution Approach 2:
The patent applies phosphor conversion partially rather than universally. By limiting phosphor to outer elements and using direct green emission from the inner element, the system achieves sufficient color reproducibility without the excessive energy loss that would result from complete phosphor conversion of all blue light.
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 significantly reduces color non-uniformity by achieving better light mixing and emission uniformity, improving the color reproducibility of light emitting devices, particularly in liquid crystal display applications.
Implementation Method 1
one or more light transmissive members each containing a phosphor and covering the light emitting elements
Data Source
AI summary
A light emitting device includes at least three light emitting elements arranged side by side, and one or more light transmissive members each containing a phosphor and covering the light emitting elements. The at least three light emitting elements include two outer light emitting elements arranged on outer sides, and an inner light emitting element arranged between the two outer light emitting elements and having a different peak emission wavelength than a peak emission wavelength of the two outer light emitting elements. The phosphor has a longer peak emission wavelength than the peak emission wavelengths of the outer light emitting elements and the peak emission wavelength of the inner light emitting element. The two outer light emitting elements and the inner light emitting element are connected in series.