Stacked LED Sub-Pixel Structure for Higher Pixel Density
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Solution Overview
Problem
Existing LED displays face challenges in efficiently utilizing sub-pixels due to costly and time-consuming mounting processes, reduced LED chip size leading to diminished luminous areas, and difficulty in increasing the area of each sub-pixel within a restricted pixel area.
Innovation Solution
A light emitting device for a display comprising a stack structure of LED stacks with buried vias and planarization layers, allowing for efficient electrical connections and reduced manufacturing time, while maintaining or increasing the luminous area of each sub-pixel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple LED chips are arranged on a two-dimensional plane to provide blue, green and red light, then various colors can be realized, but the mounting process becomes costly and time consuming
Solution Approach 1:
The patent transitions from a two-dimensional arrangement of multiple LED chips to a three-dimensional stacked structure where multiple LED chips are vertically stacked and bonded together. This vertical stacking approach reduces the horizontal footprint while maintaining the capability to emit multiple colors (blue, green, red) through the stacked layers, thereby simplifying the mounting process and improving manufacturing efficiency.
2Productivity
If LED chip size is reduced to fit more sub-pixels in a restricted area, then pixel density increases, but luminous area of each LED chip decreases
Solution Approach 1:
The patent employs vertical stacking to increase pixel density without proportionally reducing the luminous area of individual LED chips. By arranging LED chips in three-dimensional stacks, the horizontal space is utilized more efficiently, allowing higher pixel density while maintaining adequate luminous area through the vertical dimension.
Solution Approach 2:
The patent implements a nested structure where multiple LED chips are stacked and bonded together in a vertical arrangement. Each LED chip in the stack contributes to the overall light emission, and the nested configuration allows efficient use of space while preserving the luminous characteristics of individual chips.
3Manufacturing precision
If multiple LED chips are used per sub-pixel, then color accuracy improves, but manufacturing complexity increases
Solution Approach 1:
The patent simplifies the mounting process by transitioning to vertical stacking, where multiple LED chips are bonded in the vertical dimension rather than requiring precise two-dimensional placement. This approach maintains color accuracy through the stacked configuration while significantly reducing mounting process complexity and manufacturing difficulty.
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 process yield and reduces manufacturing time by optimizing the mounting process, while maintaining or increasing the luminous area of each sub-pixel, thus improving the efficiency and reliability of LED displays.
Implementation Method 1
Light emitting diodes have been used in various fields including displays
Data Source
AI summary
A light emitting device for a display according to an exemplary embodiment includes a first LED stack, a second LED stack located under the first LED stack, and a third LED stack located under the second LED stack. The light emitting device further includes a first bonding layer, a second bonding layer, a first planarization layer, a second planarization layer, lower buried vias, and upper buried vias. The first planarization layer is recessed inwardly to expose an edge of the second LED stack.