Stacked RGB LED Structure for Compact Display Pixel Mounting
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Solution Overview
Problem
The existing LED display apparatuses using individual LED chips for each sub-pixel are time-consuming to manufacture and occupy a large area, making it difficult to form stable pads for surface mounting and achieving high external quantum efficiency.
Innovation Solution
A stacked light emitting device with blue, green, and red LEDs arranged vertically, where pads are formed on the peripheral region of the light generation area, allowing for stable surface mounting and increased current density, thereby improving light extraction efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If individual LED chips are arranged in each sub-pixel, then various colors can be implemented, but the number of LED chips increases and mounting process time becomes excessive
Solution Approach 1:
The patent combines multiple LED chips (blue LED, green LED, red LED) into a single integrated light emitting device with a stacked structure. The blue LED chip is positioned on the substrate, the green LED chip is stacked on the blue LED chip, and the red LED chip is stacked on the green LED chip, allowing all three colors to be implemented in one device rather than requiring separate chips for each sub-pixel.
2Adaptability or versatility
If individual LED chips are arranged in each sub-pixel, then various colors can be implemented, but the area occupied by one pixel increases
Solution Approach 1:
The patent transitions from a two-dimensional arrangement of separate LED chips in each sub-pixel to a three-dimensional stacked structure. By stacking the blue, green, and red LED chips vertically in the thickness direction, the device utilizes the third dimension (vertical stacking) to accommodate multiple color-emitting elements within a compact footprint, thereby reducing the horizontal area occupied by each pixel.
3Productivity
If current density is increased to drive LEDs under high external quantum efficiency, then light extraction efficiency improves, but the area of the light emitting device decreases making pad formation more difficult
Solution Approach 1:
The patent divides the light emitting device into distinct functional regions: a light generation region where the stacked LED chips are positioned and a separate pad region where connection pads are formed. This segmentation allows the device area to be optimized for high current density in the light generation region while providing sufficient space in the pad region for stable pad formation and surface mounting, thus resolving the conflict between efficiency and manufacturability.
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 stacked structure reduces the number of LED chips required, shortens the mounting process, and enhances external quantum efficiency by increasing current density while facilitating stable pad formation for surface mounting.
Implementation Method 1
a light generation region and a peripheral region disposed around the light generation region
Data Source
AI summary
A stacked light emitting device includes a first LED stack, a second LED stack disposed under the first LED stack, a third LED stack disposed under the second LED stack, and a plurality of pads disposed over the first LED stack. Each of the first, second, and third LED stacks has a light generation region and a peripheral region disposed around the light generation region. The plurality of pads is disposed on the peripheral region of the first LED stack.