Stacked RGB LED Layout With Peripheral Pads for Dense Displays
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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
1Productivity
If individual LED chips are arranged for each sub-pixel, then color display capability is achieved, but the number of LED chips increases and manufacturing time becomes excessive
Solution Approach 1:
The patent combines multiple LED chips (blue, green, and red LEDs) into a single integrated light emitting device with a stacked structure. The blue LED chip is positioned on the substrate, green LED chips are stacked on the blue LED chip, and red LED chips are stacked on the green LED chips, allowing all three primary colors to be emitted from one device rather than requiring separate chips for each sub-pixel.
Solution Approach 2:
The patent transitions from a two-dimensional arrangement of individual LED chips to a three-dimensional stacked structure. By stacking LED chips vertically in multiple layers (blue layer, green layer, red layer), the device achieves compact integration of multiple color-emitting elements within a small footprint, dramatically reducing the number of chips needed per display area.
2Area of stationary object
If individual LED chips are arranged for each sub-pixel, then color display capability is achieved, but the area occupied by each pixel increases
Solution Approach 1:
The patent merges multiple color-emitting LED chips into a single integrated device, allowing blue, green, and red sub-pixels to share a common structural platform. This consolidation reduces the total area required for each pixel compared to having separate chips for each sub-pixel color.
Solution Approach 2:
By stacking LED chips vertically in three dimensions rather than arranging them horizontally in two dimensions, the patent achieves compact integration of multiple color-emitting elements within a small footprint, dramatically reducing the area occupied by each pixel.
3Reliability
If current density is increased to achieve high external quantum efficiency, then light emission efficiency improves, but pad formation becomes more difficult
Solution Approach 1:
The patent divides the light emitting device into distinct functional regions: a light generation region where LED chips are positioned for light emission, and a peripheral region that provides structural support and mounting areas. Pads are specifically formed in the peripheral region, which has different mechanical properties and stress distribution compared to the light generation region, enabling stable pad formation even under high current density conditions.
Solution Approach 2:
The patent applies different structural characteristics to different regions of the device. The peripheral region is designed with specific mechanical properties and geometry that optimize it for pad formation and mechanical support, while the light generation region is optimized for light emission. This local differentiation allows pads to be formed stably in the peripheral region without compromising the high current density requirements for efficient light emission in the light generation region.
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 manufacturing time, and enhances the external quantum efficiency while facilitating stable pad formation for surface mounting.
Implementation Method 1
a first LED stack, a second LED stack disposed under the first LED stack, and 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
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.