Nanowire LED Directional Emission for Uniform Display White Point
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional LEDs emit light in a wide range of angles, lacking directionality which is desirable for certain applications like displays, and achieving directionality often compromises color uniformity across angles.
Innovation Solution
Nanowire LEDs are designed with specific geometries and optical structures to achieve directional far-field patterns while maintaining color uniformity, using optical interference and reflective regions to control light emission angles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If conventional LEDs are used with wide-angle emission, then color uniformity is maintained, but directionality is poor
Solution Approach 1:
The patent applies local quality by configuring each LED sub-pixel (red, green, blue) with specific geometric parameters tailored to its wavelength. Each sub-pixel has a distinct emission pattern designed to direct light within a specific angular range, allowing directional control while maintaining overall color uniformity through coordinated design of all sub-pixels
Solution Approach 2:
The patent changes geometric parameters of the LED sub-pixels, specifically the ratio of lateral to vertical dimensions, to control emission angles. By adjusting these parameters for each wavelength (red, green, blue), the system achieves directional emission while maintaining color consistency across different viewing angles
2Illumination intensity
If directional emission is achieved through optical structures, then light is directed in specific angles, but device complexity increases
Solution Approach 1:
The patent employs self-service by designing the LED sub-pixels to inherently produce directional emission through their geometric configuration. The LEDs themselves serve the function of beam shaping without requiring external optical elements, thereby achieving directionality while minimizing additional device complexity
Solution Approach 2:
Instead of using external optical components to shape light after emission, the patent inverts the approach by designing the light source geometry itself to emit light in the desired direction. This eliminates the need for separate optical shaping components and reduces overall system complexity
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 nanowire LEDs emit light with enhanced directionality and uniform color across angles, improving display performance by directing more light in specific angles without sacrificing color consistency.
Implementation Method 1
optical interference within each LED causes light to be emitted in a preferential direction
Implementation Method 2
a reflective region located an optical distance less than 1 μm from the active region
Data Source
AI summary
A full color display includes multiple pixels and has a white point, a direction of emission and a solid angle of emission around the direction of emission characterized by a half-cone angle θ. Each pixel includes: a sub-pixel including a red LED having a first geometry emitting red light into a range of emission angles, such that a fraction of the power emitted within the solid angle of emission is at least 1.2*(1−cos(θ)2); a sub-pixel including a green LED having a second geometry emitting green light into a range of emission angles, such that a fraction of the power emitted within the solid angle of emission is at least 1.2*(1−cos(θ)2); and a sub-pixel including a blue LED emitting blue light into a range of emission angles, such that a fraction of the power emitted within the solid angle of emission is at least 1.2*(1−cos(θ)2). The LEDs are configured such that, in any direction within the solid angle of emission, white light emitted by the display has a chromaticity difference Du′v′ from the white point of the display which is less than 0.01.