Stacked LED Pixel Structure for RGB Mixing and Higher Luminance
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Solution Overview
Problem
Current display apparatuses using white light as a backlight source face challenges in luminous intensity and productivity due to the large number of LEDs required, which increases manufacturing time and costs, and struggle to achieve a consistent RGB mixing ratio for high-quality white light emission.
Innovation Solution
A light emitting device with a stacked structure of LEDs, where each pixel includes a first LED stack generating a first peak wavelength, a second LED stack generating a second peak wavelength, and a third LED stack generating a third peak wavelength, allowing for reduced mounting time and increased luminous area without increasing pixel size, and enabling easier control of the RGB mixing ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If individual LED chips are arranged on a two-dimensional plane to display various colors, then the display can show images, but the number of LED chips increases excessively, requiring excessive mounting time and lowering productivity
Solution Approach 1:
The patent transitions from a two-dimensional arrangement of LED chips to a three-dimensional stacked structure where multiple LED stacks are vertically arranged. This vertical stacking allows multiple color-emitting LEDs to occupy the same planar footprint, dramatically reducing the number of mounting locations required while maintaining full color display capability through the stacked layers emitting red, green, and blue light respectively
2Area of stationary object
If the area of each LED chip is reduced to arrange sub-pixels in a restricted area, then more sub-pixels can fit in the pixel area, but it becomes difficult to mount the LED chips and luminous area decreases, reducing luminous intensity
Solution Approach 1:
By stacking multiple LED structures vertically, the patent increases the effective luminous area without expanding the planar pixel footprint. Each LED stack in the vertical arrangement contributes its own luminous area, so the total luminous area is the sum of all stacked LED areas, thereby increasing overall luminous intensity while maintaining compact pixel dimensions
3Illumination intensity
If blue LEDs have very high luminous intensity compared to other LEDs, then blue light emission is strong, but it becomes difficult to match the RGB mixing ratio for standard white light
Solution Approach 1:
The patent applies different structural configurations to different LED stacks within the same pixel. By varying the number of quantum wells, active layer thicknesses, or stack arrangements in red, green, and blue LED stacks, each stack's light output can be independently tuned. This allows precise control of the RGB mixing ratio to achieve standard white light (D65) despite inherent differences in individual LED luminous intensities
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 increases the area of each sub-pixel, reduces manufacturing time, enhances production yield, and allows for precise control of the RGB mixing ratio, improving the luminous intensity and color accuracy of the display apparatus.
Implementation Method 1
a first LED stack configured to generate light having a first peak wavelength, a second LED stack configured to generate light having a second peak wavelength, and a third LED stack configured to generate light having a third peak wavelength
Data Source
AI summary
A display apparatus including a circuit board and a plurality of pixels arranged on the circuit board, in which at least one of the pixels includes a first light emitting device and a second light emitting device spaced apart from each other in a lateral direction, the first light emitting device includes a first LED stack configured to generate light having a first peak wavelength; and the second light emitting device includes a second LED stack configured to generate light having a second peak wavelength, and a third LED stack disposed on the second LED stack and configured to generate light having a third peak wavelength.