Stacked LED Sub-Pixels for Higher Brightness in Limited Pixel Area
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Solution Overview
Problem
Micro LEDs in display apparatus face challenges in manufacturing due to their small size, making handling and mounting difficult, and the arrangement of sub-pixels within a limited area leads to reduced brightness due to smaller luminous areas.
Innovation Solution
The implementation of a light emitting diode (LED) stack with vertically stacked sub-pixels, where at least two sub-pixels are stacked to reduce the surface area required for each pixel, and the use of a partial reflective layer and semiconductor layer bandgap control to manage brightness, allowing for independent driving of sub-pixels and simultaneous manufacturing on a wafer level.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If micro LEDs are arranged on a two-dimensional plane to correspond to each pixel, then the display can be implemented, but the area occupied by one pixel increases and the luminous area of each sub-pixel decreases
Solution Approach 1:
The patent transitions from a two-dimensional arrangement of sub-pixels to a three-dimensional vertical stack configuration. Multiple LED sub-units are stacked vertically within each pixel, allowing light to be emitted in multiple directions (forward and backward) from each vertical position, effectively utilizing the third dimension to increase luminous area without expanding pixel footprint.
Solution Approach 2:
The patent implements nested structures where multiple LED sub-units are stacked within each other vertically. Each LED sub-unit is positioned above or below another, creating a nested arrangement that maximizes light emission within the confined pixel area while maintaining or increasing brightness through cumulative luminous output.
2Productivity
If the area of each sub-pixel is reduced to fit more sub-pixels within a limited area, then more pixels can be arranged, but the brightness of sub-pixels deteriorates
Solution Approach 1:
By stacking LED sub-units vertically, the patent increases the number of light-emitting elements within each pixel without reducing the lateral dimensions. This vertical arrangement allows more pixels to be packed into the same area while each pixel maintains high brightness through multiple vertically-stacked light sources.
Solution Approach 2:
The patent combines multiple LED sub-units into a single vertical stack within each pixel, merging their light emission capabilities. This consolidation allows the pixel to achieve high brightness through the combined output of multiple sub-units while occupying the same lateral space as a single sub-pixel would.
3Manufacturing precision
If micro LEDs are individually mounted on a display panel, then precise positioning can be achieved, but the manufacturing process becomes complex and time-consuming
Solution Approach 1:
The patent combines multiple LED sub-units into pre-assembled vertical stacks that are manufactured together as integrated units. These stacked structures can then be transferred and positioned as single components, dramatically simplifying the manufacturing process while maintaining precise positioning accuracy through reduced handling steps.
Solution Approach 2:
The patent performs preliminary assembly of multiple LED sub-units into vertical stacks during the manufacturing process, before final placement on the display panel. This preliminary action of pre-assembling the stacks reduces the complexity of subsequent mounting operations and improves manufacturing efficiency.
4Measurement precision
If a large number of micro LEDs are transferred to make a single display, then the display resolution increases, but handling and mounting becomes increasingly difficult
Solution Approach 1:
The patent merges multiple micro LEDs into integrated vertical stacks, reducing the total number of separate components that need to be handled and mounted. This consolidation maintains high display resolution through the stacked arrangement while dramatically easing handling and mounting operations through reduced component count.
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
This approach increases the light emitting area of each sub-pixel without increasing the pixel area, maintains display characteristics, and enables efficient manufacturing by obviating individual mounting of micro LEDs, while enhancing brightness and operational efficiency.
Implementation Method 1
a first color filter interposed between the first LED sub-unit and the second LED sub-unit, and configured to transmit light generated in the first LED sub-unit and to reflect light generated in the second LED sub-unit
Implementation Method 2
a second color filter interposed between the second LED sub-unit and the third LED sub-unit, and configured to transmit light generated in the first and second LED sub-units and to reflect light generated in the third LED sub-unit
Implementation Method 3
a first LED stack, a second LED stack disposed on the first LED stack, and a third LED stack disposed on the second LED stack
Data Source
AI summary
A light emitting diode (LED) pixel for a display including a first LED stack having a first well layer, a second LED stack disposed on the first LED stack and having a second well layer, a third LED stack disposed on the second LED stack and having a third well layer, a first electrode disposed on the first LED stack and in ohmic contact with the first LED stack, a second electrode disposed on the second LED stack and in ohmic contact with a surface of the second LED stack, and a third electrode in ohmic contact with a surface of the third LED stack, in which the first well layer includes at least one base material different from that of the second well layer.