Stacked RGB LED Structure for Pixel Density and White-Light Balance
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Solution Overview
Problem
Conventional LED displays face challenges in reducing the size of LED chips to increase pixel density while maintaining luminous intensity ratios and efficiency, leading to difficulties in mounting and achieving high-quality white light production.
Innovation Solution
A light emitting device with a stacked structure of three LED sub-units emitting red, blue, and green light, where the third LED sub-unit is closer to the substrate with irregularities to enhance luminous intensity, and a protection layer is used to facilitate handling and protection during manufacturing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If LED chips are reduced in size to increase pixel density, then the area of each pixel can be reduced, but mounting becomes difficult and luminous intensity decreases
Solution Approach 1:
The patent transitions from a two-dimensional arrangement of LED chips to a three-dimensional stacked structure. Multiple LED sub-units (red, green, blue) are vertically stacked on top of each other, allowing sub-pixels to be arranged in the depth direction rather than only in the plane. This enables increased pixel density without reducing individual LED chip sizes, thereby maintaining ease of mounting while achieving higher resolution.
Solution Approach 2:
The patent implements a nested structure where LED sub-units are stacked hierarchically. The first, second, and third LED sub-units are positioned at different heights, with each sub-unit containing multiple LED chips that emit different colors. This nested arrangement allows efficient use of vertical space, increasing pixel density without compromising the manufacturability of individual LED components.
2Area of moving object
If LED chips are reduced in size to increase pixel density, then more pixels can be arranged in restricted area, but luminous area of LED chips is reduced
Solution Approach 1:
By stacking LED sub-units vertically in the third dimension, the patent increases the total luminous area available within a restricted pixel footprint. Each sub-unit contributes additional luminous area, so even though individual chips may be smaller, the cumulative luminous area across multiple stacked layers maintains or enhances overall luminous intensity.
Solution Approach 2:
The patent combines multiple LED sub-units emitting different colors (red, green, blue) into a single integrated pixel structure. This merging of multiple light sources in the vertical direction allows the system to achieve full-color display capability while maintaining sufficient luminous intensity for each color channel, as each sub-unit can be optimized for its specific color emission.
3Illumination intensity
If conventional LED chips are used, then blue LED has very high luminous intensity, but it is difficult to match the RGB mixing ratio for standard white light
Solution Approach 1:
The patent applies local quality by using different LED chip sizes and configurations in different sub-units to achieve uniform RGB mixing. The first LED sub-unit (red), second LED sub-unit (green), and third LED sub-unit (blue) can have different numbers of chips, different chip areas, or different luminous efficiencies tailored to compensate for the inherently higher intensity of blue LEDs. This localized optimization allows precise control of the overall RGB mixing ratio to match the D65 standard.
Solution Approach 2:
The patent changes key parameters such as the number of LED chips per sub-unit, the area of each chip, and the stacking configuration to adjust luminous intensity ratios. By varying these parameters across different sub-units, the system can balance the RGB output to achieve the target mixing ratio, overcoming the challenge of blue LEDs' naturally high intensity.
4Adaptability or versatility
If one LED chip is provided for each sub-pixel in a two-dimensional arrangement, then color display is achieved, but the number of LED chips increases and mounting time is excessive
Solution Approach 1:
The patent moves from a two-dimensional spread-out arrangement to a three-dimensional stacked configuration. Instead of placing red, green, and blue LED chips side-by-side in the plane, they are stacked vertically within a compact pixel volume. This reduces the total number of discrete mounting operations required and enables more efficient manufacturing processes such as batch mounting of stacked units.
Solution Approach 2:
The stacked LED sub-unit structure serves multiple functions simultaneously: it provides color emission (red, green, blue), achieves compact pixel density, and simplifies the mounting process. By integrating multiple LED chips and control circuits into a single stacked module, the system reduces the number of separate mounting steps while maintaining full color display capability.
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 RGB mixing ratios, improving the efficiency and quality of light emission.
Implementation Method 1
a third LED sub-unit disposed closer to the substrate with irregularities to enhance luminous intensity
Data Source
AI summary
A light emitting device for a display including: a base layer; a first LED sub-unit, a second LED sub-unit, and a third LED sub-unit on the base layer; and a supporting layer covering the first LED sub-unit, the second LED sub-unit, and the third LED sub-unit, in which the third LED sub-unit is configured to emit light having a shorter wavelength than that of light emitted from the first LED sub-unit, and to emit light having a longer wavelength than that of light emitted from the second LED sub-unit, and a luminous intensity ratio of light emitted from the third LED sub-unit and the second LED sub-unit is configured to be about 6:1.