Micro LED Pixel Stacking With Dichroic Filtering for Color Purity
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Solution Overview
Problem
Micro LED display devices face challenges in reducing the area occupied by each pixel unit while maintaining high color purity and pixel density, as existing designs often result in light from one pixel unit entering adjacent units, affecting color emission and efficiency.
Innovation Solution
The micro LED display device stacks light-emitting units vertically, with a dichroic filtering layer and embankment structures to ensure red, green, and blue light emit upward, and uses wavelength converting layers and absorbing layers to prevent crosstalk, allowing for a more compact design and enhanced pixel density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If light-emitting units are arranged horizontally in traditional display devices, then the structure is simple to manufacture, but the area occupied by each pixel unit is large and light crosstalk between adjacent units occurs
Solution Approach 1:
The patent transitions from traditional horizontal planar arrangement of light-emitting units to a vertical stacked configuration. Multiple light-emitting units (first, second, and third light-emitting units) are arranged along the vertical direction, with each unit containing sub-units (first, second, third light-emitting sub-units) stacked vertically. This dimensional change from 2D horizontal layout to 3D vertical stacking significantly reduces the area occupied by each pixel unit while maintaining manufacturing feasibility through sequential layer fabrication.
Solution Approach 2:
The patent implements a nested structure where multiple light-emitting units are contained within vertically stacked configurations. Each light-emitting unit contains multiple light-emitting sub-units nested within it, and multiple such units are nested vertically with transparent substrates and filtering layers. This nested arrangement maximizes space utilization and reduces the horizontal footprint of each pixel unit.
2Manufacturing precision
If embankment structures are added to prevent light crosstalk, then color purity is enhanced, but the area occupied by each pixel unit increases
Solution Approach 1:
Instead of expanding embankment structures horizontally to prevent light crosstalk, the patent moves the light-emitting units vertically apart from each other. The vertical stacking configuration with transparent substrates separating units eliminates the need for large horizontal embankment structures, as light crosstalk is prevented by the vertical separation and selective filtering rather than horizontal containment walls.
Solution Approach 2:
The patent extracts the light-emitting units from a horizontal planar arrangement and relocates them to vertical stacking positions. By taking out the units from the traditional horizontal configuration and placing them in vertical layers separated by transparent substrates, the need for extensive embankment structures is eliminated, reducing the area occupied by each pixel unit while maintaining color purity through vertical isolation.
3Quantity of substance
If multiple light-emitting units are stacked vertically, then pixel density is enhanced and area is reduced, but light from lower units may enter upper units affecting color emission
Solution Approach 1:
The patent introduces transparent substrates and dichroic filtering layers as intermediary elements between vertically stacked light-emitting units. The transparent substrates physically separate the units while allowing light transmission, and the dichroic filtering layers selectively transmit specific wavelengths while blocking others. These intermediaries prevent light crosstalk between units by filtering out unwanted wavelengths from lower units before they reach upper units, enabling high pixel density vertical stacking without color contamination.
Solution Approach 2:
The patent applies different optical properties to different parts of the vertical stack. Each light-emitting unit is designed with specific wavelength characteristics, and dichroic filtering layers are positioned at specific locations to selectively transmit or block specific wavelengths. This local optimization of optical properties ensures that each unit emits its designated color while filtering layers prevent unwanted wavelengths from adjacent units, maintaining color purity in the high-density vertical configuration.
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 configuration ensures efficient upward emission of red, green, and blue light, reducing the area occupied by each pixel unit and enhancing color purity and pixel density, allowing for more display devices in a unit area.
Implementation Method 1
The dichroic filtering layer is disposed between the first light-emitting unit and the first transparent substrate. The dichroic filtering layer is configured to allow the first color light to pass therethrough and block the second color light.
Implementation Method 2
The wavelength converting layer covers the chip, and is configured to convert the third color light emitted by the chip to the first color light.
Implementation Method 3
The color resisting layer is configured to allow the first color light and the second color light to pass therethrough, and to absorb the third color light.
Data Source
AI summary
A micro LED display device includes a carrier, a first light-emitting unit, a first transparent substrate, a second light-emitting unit and a dichroic filtering layer. The first light-emitting unit is disposed on the carrier and is used to emit a first color light. The first transparent substrate is disposed on the first light-emitting unit. The second light-emitting unit is disposed on the first transparent substrate and is used to emit a second color light. The dichroic filtering layer is disposed between the first light-emitting unit and the first transparent substrate. The dichroic filtering layer is used to allow the first color light to pass therethrough and block the second color light.