Stacked Passive-Drive Micro LED Display for High Brightness
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Solution Overview
Problem
Passive drive micro LED displays face challenges in achieving high-definition and high-luminance images due to reduced energization time and brightness, especially in small-lot production where active drive technologies are costly and unsuitable.
Innovation Solution
A display device with two stacked micro LED units, where the second substrate's light emitters are arranged non-overlapping with the first substrate's, using a transparent protective material and a refractive index difference to refract light and prevent brightness loss, allowing for independent driving and high-definition imaging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If subpixels are arranged on a two dimensional plane to increase area per subpixel, then brightness is improved, but the area occupied by each subpixel increases and the overall display area is reduced
Solution Approach 1:
The patent transitions from a two-dimensional arrangement of subpixels to a three-dimensional stacked configuration. Multiple substrates are stacked vertically with light emitters arranged at different heights, allowing subpixels to be positioned in three-dimensional space rather than confined to a single plane. This enables increased display area without compromising the area available for light emission in each subpixel.
2Area of stationary object
If subpixels are arranged in a limited area by reducing area per subpixel, then display area is improved, but brightness of subpixels is reduced
Solution Approach 1:
By stacking multiple substrates vertically, the patent creates additional spatial dimensions for arranging subpixels. This allows the display to expand in the vertical direction while maintaining adequate area for light emission in each subpixel, thereby increasing overall display area without sacrificing brightness.
Solution Approach 2:
The patent combines multiple substrates with light emitters into a single stacked structure. By merging several layers of subpixels from different substrates, the overall display area is increased while each individual subpixel maintains sufficient emission area for adequate brightness.
3Device complexity
If passive drive mode is used to reduce device complexity and production cost, then manufacturing simplicity is improved, but energization time and brightness are reduced
Solution Approach 1:
The patent divides the display into multiple independent substrates, each capable of being driven separately. This segmentation allows the passive drive system to manage multiple discrete light-emitting layers, effectively distributing the energization requirements across time and space, thereby maintaining adequate brightness while preserving manufacturing simplicity.
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 enables high-definition and high-luminance display by preventing brightness reduction and allowing for efficient energization of pixels, even in passive drive mode, while reducing production costs by minimizing the need for complex masks and transistors.
Implementation Method 1
a refractive index of the second substrate is greater than a refractive index of the transparent protective material, and light emitted from the first light emitter is refracted toward a normal due to a difference in a refractive index between the transparent protective material and the second substrate
Data Source
AI summary
A display device includes a first substrate and a second substrate. The first substrate is a passive drive substrate. The first substrate includes a plurality of first light emitters arranged two dimensionally. The first light emitters are arranged at respective intersections of a plurality of data lines and a plurality of scan lines. The second substrate is a passive drive light transmissive substrate. The second substrate includes a plurality of second light emitters arranged two dimensionally. The second light emitters are arranged at respective intersections of the plurality of data lines and the plurality of scan lines. The second substrate is stacked over the first substrate, such that the second light emitters are provided at respective positions not overlapping with the first light emitters.