RGB LED Stack Layout for Faster Display Pixel Mounting
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Solution Overview
Problem
The existing LED display technologies face challenges in reducing time consumption during the mounting process due to the need for precise arrangement of light emitting diodes (LEDs) and restrictions on stacking sequences based on light wavelengths, as well as interference from electrodes affecting light emitting regions.
Innovation Solution
A light emitting device structure is developed where multiple LED units are stacked horizontally on a display substrate, allowing for independent emission of red, green, and blue light without wavelength-dependent stacking restrictions, using bonding layers and electrodes to facilitate efficient color mixing and pixel formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If individual light emitting devices are arranged on each subpixel to realize various colors, then color accuracy is improved, but the number of light emitting devices increases, causing time consumption in mounting process to increase
Solution Approach 1:
The patent combines multiple LED units (first LED unit with first light emitting stack, second LED unit with second light emitting stack, and third LED unit with third light emitting stack) into a single integrated light emitting device. This merging reduces the total number of separate devices that need to be mounted on the display substrate, thereby decreasing mounting time while maintaining the ability to produce various colors through the combined operation of the stacked LED units.
Solution Approach 2:
The patent transitions from a planar arrangement of individual LEDs to a three-dimensional stacked structure. The first, second, and third LED units are stacked vertically (in the thickness direction) rather than being arranged horizontally on separate subpixels. This dimensional change allows multiple color-emitting elements to coexist in a single mounting position, reducing the number of mounting operations required.
2Loss of time
If light emitting devices are stacked vertically to reduce the number of devices per pixel, then mounting time is reduced, but stacking sequence is restricted by wavelengths of light emitted
Solution Approach 1:
The patent extracts the wavelength-dependent constraint from the stacking structure by introducing a wavelength selection layer. This layer selectively transmits specific wavelengths while blocking others, allowing LED units to be stacked in any sequence without worrying about wavelength interference. The wavelength selection layer acts as an intermediary that decouples the physical stacking order from the optical emission requirements.
3Reliability
If electrodes are added to connect stacked LED units, then electrical connectivity is improved, but electrodes interfere with light emitting regions
Solution Approach 1:
The patent applies local quality by making the electrodes transparent in the regions where light emission occurs. The electrodes are configured to be transparent to the wavelengths of light emitted by the adjacent LED units, allowing electrical connectivity to be established without blocking or interfering with the light emission from the active regions of the stacked LEDs.
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 reduces the number of LEDs required per pixel, enhances color mixing, and allows for flexible stacking sequences, thereby decreasing mounting time and improving contrast ratios while maintaining efficient light emission.
Implementation Method 1
a first bonding layer coupling the first LED unit to the second LED unit, and a second bonding layer coupling the second LED unit to the third LED unit
Implementation Method 2
Each of the first to third light emitting stacks includes a first conductivity type semiconductor layer and a second conductivity type semiconductor layer
Data Source
AI summary
A display apparatus includes a display substrate, and light emitting devices arranged on an upper surface of the display substrate. At least one of the light emitting devices includes a first LED unit including a first light emitting stack, a second LED unit including a second light emitting stack, and a third LED unit including a third light emitting stack. The second LED unit is disposed between the first LED unit and the third LED unit. Each of the first to third light emitting stacks includes a first conductivity type semiconductor layer and a second conductivity type semiconductor layer. The first conductivity type semiconductor layer and the second conductivity type semiconductor layer in each of the first to third light emitting stacks are stacked in a horizontal direction with respect to the upper surface of the display substrate.