Stacked RGB LED Structure for Stable Pads and Narrow Viewing Angle
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Solution Overview
Problem
The existing LED display apparatus with a stacked structure faces challenges in forming stable pads for surface mounting, increasing current density, and reducing light interference and viewing angle differences between blue, green, and red LEDs, which affects image implementation and efficiency.
Innovation Solution
A light emitting device with a stacked structure comprising a first, second, and third LED stack, along with connectors and pads, is designed to stabilize the structure for surface mounting, reduce light interference, and narrow the viewing angle by covering a significant portion of the side surfaces of the LED stacks, thereby improving the mounting process and display quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a stacked structure with multiple LED stacks is used to reduce the number of light emitting devices, then the mounting process time is reduced and device density is increased, but it becomes difficult to form stable pads for surface mounting
Solution Approach 1:
The patent transitions from a two-dimensional arrangement of separate LED chips to a three-dimensional stacked structure where multiple LED stacks are vertically arranged. This dimensional change allows multiple light emitting devices to be mounted in a smaller footprint area, reducing mounting complexity and time while maintaining pad stability through the vertical stacking architecture with connectors between layers
2Power
If the area of the light emitting device is reduced to increase current density, then the external quantum efficiency is improved, but it becomes more difficult to form stable pads
Solution Approach 1:
The patent resolves this contradiction by moving to a three-dimensional stacked configuration. The vertical stacking allows each individual LED stack to have a reduced footprint area for high current density operation, while the overall device structure maintains sufficient area through the vertical dimension. This enables both high power density and stable pad formation on the extended structure
3Adaptability or versatility
If blue, green, and red LEDs are arranged on a two-dimensional plane, then various colors can be displayed, but a relatively large area is occupied by each pixel
Solution Approach 1:
The patent applies vertical stacking to arrange blue, green, and red LED stacks in the vertical dimension rather than spreading them horizontally. This three-dimensional configuration maintains the full color display capability while significantly reducing the horizontal footprint of each pixel, enabling higher resolution displays with smaller pixel pitches
4Productivity
If light emitting devices are arranged in a stacked structure, then the number of devices is reduced to 1/3, but light interference occurs between adjacent pixels due to widened viewing angles
Solution Approach 1:
The patent extracts and removes the harmful lateral light emission from the stacked LED structure. By taking out the unwanted wide-angle light that causes interference between adjacent pixels, the design maintains the high device density benefit while eliminating the harmful optical crosstalk, achieving both high productivity and clean image display
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 enhances the stability of the light emitting device for surface mounting, reduces light interference between pixels, and narrows the viewing angle, leading to improved display performance and manufacturing efficiency.
Implementation Method 1
at least one of the third-1 connector and the third-2 connector covers a side surface of the peripheral region of the third LED stack
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, a third-1 connector and a third-2 connector disposed between the second LED stack and the third LED stack, and a plurality of pads disposed over the first LED stack, and electrically connected to the first, second, and third LED stacks. Each of the first, second, and third LED stacks has a light generation region and a peripheral region disposed around the light generation region.