Asymmetric CSP LED Reflective Cup for Backlight Uniformity
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Solution Overview
Problem
Current LED packages, including PLCC and CSP types, cannot achieve an asymmetrical radiation pattern without increasing manufacturing costs and package size, which is undesirable for applications requiring specific light distribution patterns in LCD backlight modules.
Innovation Solution
Designing top-view and side-view CSP LEDs with asymmetrically shaped reflective surfaces and light-transmitting structures that partially cover the photoluminescent or light-transmitting structures to control light emission, allowing for asymmetrical radiation patterns without the need for additional optical lenses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If an extra optical lens or secondary optical lens is incorporated to achieve an asymmetrical radiation pattern, then the desired radiation pattern is obtained, but the manufacturing cost increases and the overall space is greatly increased
Solution Approach 1:
The patent applies asymmetry by designing the reflective cup structure with non-uniform reflective properties in different directions. Specifically, the reflective cup has different reflective rates along the first horizontal direction versus the second horizontal direction, creating an asymmetrical radiation pattern without requiring additional optical lenses. This directly resolves the contradiction by achieving the desired shape (radiation pattern) while avoiding the complexity and size increase that would result from adding optical components.
Solution Approach 2:
The patent implements local quality by varying the reflective properties at different locations and orientations of the reflective cup structure. The reflective cup is designed with different reflective rates for different spatial directions, allowing localized control of light reflection. This enables the generation of asymmetrical radiation patterns through distributed local modifications rather than adding global optical components, thereby reducing manufacturing cost and package size.
2Shape
If a portion of the reflective cup structure is fabricated to be light-transmitting to change the radiation pattern, then the radiation pattern can be changed, but the reflective cup structure is difficult to fabricate using mass production processes
Solution Approach 1:
The patent applies parameter changes by modifying the reflective rate parameter of the reflective cup structure rather than changing its fundamental light-transmitting or light-blocking properties. By adjusting the reflective rate in different directions through material composition or surface treatment parameters, the radiation pattern is controlled while maintaining compatibility with existing mass production molding processes. This avoids the fabrication difficulties associated with creating light-transmitting portions in the reflective cup.
3Illumination intensity
If a larger angle of radiation pattern along the length direction is used, then a more uniform incident light distribution is achieved and dark spots are reduced, but the viewing angle along the width direction should be smaller to prevent light leakage
Solution Approach 1:
The patent applies local quality by implementing direction-dependent reflective properties in the reflective cup structure. The reflective cup is designed to provide different reflective rates along the first horizontal direction (length direction) versus the second horizontal direction (width direction). This localized directional control allows the structure to expand light distribution in the length direction for uniformity while simultaneously containing light in the width direction to prevent leakage, effectively resolving the contradiction between these two opposing requirements.
Solution Approach 2:
The patent uses asymmetry by creating an inherently directional reflective cup structure with non-uniform reflective properties. The asymmetrical design allows the radiation pattern to have a larger half viewing angle along the length direction for uniform light distribution while maintaining a smaller half viewing angle along the width direction to prevent light leakage. This asymmetrical configuration simultaneously addresses both requirements without compromise.
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 enables the production of LEDs with controlled radiation angles, reducing manufacturing costs and maintaining a compact size while providing improved light distribution and reduced light loss in LCD backlight modules.
Implementation Method 1
Reflective materials are also used as a part of the package structure so that desirable light-emitting directions can be achieved
Implementation Method 2
photoluminescent materials are typically dispensed to cover the radiation path of the LED chip so that a portion of the primary light is converted as secondary light by the photoluminescent materials
Data Source
AI summary
An asymmetrically shaped chip-scale packaging (CSP) light-emitting device (LED) includes an LED chip, a photoluminescent structure (or a light-transmitting structure), and a reflective structure. The photoluminescent structure covers the upper surface and/or the edge surface of the LED chip; and the reflective structure at least partially covers the edge surface of the photoluminescent structure. The reflective structure partially reflects the primary light emitted from the edge surface of the LED chip or the converted secondary light radiated from the edge surface of the photoluminescent structure, therefore shaping the radiation pattern asymmetrically.