Non-Rectangular LED Chip Geometry for Backlight Uniformity
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Solution Overview
Problem
Current light-emitting devices, particularly side-view light-emitting devices for backlights, face challenges in miniaturization, light extraction efficiency, and uniformity of light output due to the rectangular shape of LED chips and the arrangement of light-emitting elements, leading to unevenness in color and luminance.
Innovation Solution
The design incorporates a package with a recessed portion housing two light-emitting elements of non-rectangular shapes, such as parallelograms, aligned in the longitudinal direction, with a wavelength conversion member between them to enhance light extraction and uniformity, using a light-transmissive sealing resin and a light-reflective resin unit to optimize light distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If rectangular LED chips are used and light-emitting elements are arranged with long sides parallel to light guide plate surfaces, then the device structure is simple and easy to manufacture, but light extraction efficiency is insufficient and color uniformity is poor
Solution Approach 1:
The patent applies asymmetry by changing the LED chip shape from rectangular to trapezoidal, where the bottom surface has different width than the top surface. This asymmetric geometry enables better light extraction by allowing light to exit through multiple surfaces at different angles, improving illumination uniformity while maintaining manufacturing feasibility through standard mounting techniques.
2Ease of manufacture
If rectangular LED chips are used and light-emitting elements are arranged with long sides parallel to light guide plate surfaces, then the device structure is simple and easy to manufacture, but color uniformity and luminance uniformity are poor
Solution Approach 1:
The trapezoidal chip geometry creates asymmetric light emission patterns that improve color uniformity. The slanted sides allow light to be extracted at various angles and positions, reducing the concentration of light in specific areas and achieving more uniform color distribution across the light guide plate surface.
Solution Approach 2:
The patent applies local quality by positioning wavelength conversion members specifically in regions where light extraction needs enhancement. The conversion members are strategically placed to convert light from specific LED chips at optimal locations, ensuring uniform color output across different areas of the backlight assembly.
3Illumination intensity
If wavelength conversion members are added to improve light extraction efficiency and uniformity, then light extraction efficiency and color uniformity improve, but device complexity increases
Solution Approach 1:
The patent merges the wavelength conversion function directly into the sealing resin that already fills the recessed portion. By incorporating wavelength conversion particles into the sealing resin, the patent eliminates separate conversion layers or components, reducing device complexity while maintaining improved light extraction efficiency and color uniformity.
Solution Approach 2:
The sealing resin serves multiple functions: it provides electrical insulation, mechanical support, and wavelength conversion. By making the sealing resin multi-functional, the patent avoids adding separate components for each function, thereby improving light extraction efficiency without proportionally increasing device complexity.
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 improves light extraction efficiency and reduces unevenness in color and luminance, enabling a more uniform and efficient light output suitable for applications like liquid-crystal display backlights.
Implementation Method 1
The wavelength conversion member is provided in the recessed portion so as to convert light from the first light-emitting element into light having a different wavelength
Data Source
AI summary
A light-emitting device includes a package having a recessed portion defined by a bottom surface and lateral walls surrounding the bottom surface, first and second light-emitting elements aligned in the longitudinal direction on the bottom surface, and a wavelength conversion member in the recessed portion, the wavelength conversion member converting light from the first light-emitting element. The first and second light-emitting elements each have a polygonal shape other than a rectangular shape in a front view. The first and second light-emitting elements are disposed away from each other so that a longest side of each light-emitting element will be substantially parallel to the longitudinal direction of the bottom surface and so that sides facing each other will be substantially parallel to each other. The wavelength conversion member is disposed at least in a region on the bottom surface between the first and second light-emitting elements.