Stacked RGB LED Pixel Structure for Viewing Angle and Color Mixing
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Solution Overview
Problem
Existing LED display apparatuses face challenges in increasing sub-pixel area within a restricted pixel area, reducing mounting time, achieving precise RGB mixing ratios, and adjusting viewing angles of light emitted from pixels.
Innovation Solution
The display apparatus incorporates a light emitting device with a stacked structure of first, second, and third LED sub-units, where the third LED sub-unit is positioned closer to the upper surface than the first LED sub-unit, along with a light blocking layer and a transparent layer to enhance light transmission and adjust viewing angles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If one LED chip is arranged in each sub-pixel on a two-dimensional plane, then the display apparatus can emit various colors, but the number of LED chips increases and requires excessive mounting time
Solution Approach 1:
The patent transitions from a two-dimensional arrangement of LED chips to a three-dimensional stacked structure. Multiple LED chips (first, second, and third LED chips) are vertically stacked within a single sub-pixel region, enabling full-color emission while reducing the number of chips that need to be mounted on the substrate.
Solution Approach 2:
The patent combines multiple LED chips that would traditionally be separate sub-pixels into a single integrated light emitting device. The stacked LED chips share common electrode structures and are controlled by a single pixel electrode, effectively merging multiple mounting operations into one.
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 display, but mounting becomes more difficult and luminous area decreases
Solution Approach 1:
By stacking LED chips vertically in the third dimension, the patent increases the effective luminous area within the same planar footprint. Each LED chip in the stack contributes to the overall luminous output without requiring additional horizontal space, thus maintaining ease of mounting while maximizing area utilization.
3Illumination intensity
If the viewing angle of light emitted from one pixel is increased, then light coverage is improved, but interference between adjacent pixels occurs and image quality deteriorates
Solution Approach 1:
The patent introduces a light blocking layer with specific local properties between adjacent pixel regions. This layer selectively blocks light in certain directions while allowing light emission in others, creating different optical characteristics for different regions of the display to prevent crosstalk.
Solution Approach 2:
The light blocking layer acts as an intermediary element between the LED chips and the external environment, as well as between adjacent pixels. It mediates the light propagation paths to achieve appropriate viewing angles without causing interference between neighboring pixels.
4Illumination intensity
If conventional LED chips with high blue luminous intensity are used, then blue light emission is strong, but the RGB mixing ratio cannot be matched to achieve standard white light
Solution Approach 1:
The patent assigns different luminous intensity characteristics to different LED chips in the stack. The first, second, and third LED chips are selected with specific luminous intensities that compensate for the inherently high blue intensity of conventional LEDs, allowing the combined output to achieve the target RGB mixing ratio for D65 white light.
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 allows for increased sub-pixel area without expanding the pixel area, reduces the time required for mounting, facilitates easier control of RGB mixing ratios, and adjusts the viewing angles of light emitted from pixels to improve image quality.
Implementation Method 1
a light blocking layer disposed between the light emitting devices
Implementation Method 2
a transparent layer covering the light emitting devices and the light blocking layer
Data Source
AI summary
A display apparatus including a display substrate, light emitting devices disposed on the display substrate, circuit electrodes disposed between the light emitting devices and the display substrate, and a transparent layer covering the light emitting devices and the circuit electrodes, in which at least one of the light emitting devices includes a first LED sub-unit configured to emit light having a first wavelength, a second LED sub-unit adjacent to the first LED sub-unit and configured to emit light having a second wavelength, a third LED sub-unit adjacent to the second LED sub-unit and configured to emit light having a third wavelength, and a substrate disposed on the third LED sub-unit, in which a difference in refractive indices between the 10 transparent layer and air is less than a difference in refractive indices between the substrate and a semiconductor layer of the third LED sub-unit.