Quantum Dot Light-Emitting Element for Oblique Peeping Prevention
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Solution Overview
Problem
Display devices with liquid crystal viewing angle control units experience reduced light intensity and vulnerability to peeping from oblique directions due to light passing through the liquid crystal layer.
Innovation Solution
A light-emitting element with a reflective surface and a transparent electrode, incorporating a light-emitting layer with red, green, and blue quantum dots that emit light of different peak wavelengths, where the optical path length difference and emission angle control the intensity of light interference, enhancing light intensity off-normal directions and reducing visibility from oblique angles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If light passes through the liquid crystal layer in the viewing angle control unit, then viewing angle control is achieved, but light intensity is reduced
Solution Approach 1:
The patent extracts the viewing angle control function from the liquid crystal layer and implements it through the quantum dot layer's inherent optical properties. By designing the quantum dot layer to emit light with different intensities at different angles without requiring light to pass through a liquid crystal layer, the patent eliminates the light intensity reduction problem while maintaining viewing angle control capability
Solution Approach 2:
The patent changes the emission parameters of the quantum dots to achieve viewing angle control. Specifically, it uses quantum dots with different size distributions to emit light at different wavelengths and angles, controlling the viewing angle through the spectral and angular characteristics of quantum dot emission rather than through liquid crystal modulation
2Ease of operation
If light passes through the liquid crystal layer, then viewing angle control is achieved, but peeping from oblique directions becomes possible
Solution Approach 1:
The patent applies local quality by creating different emission characteristics in different angular directions through the quantum dot layer structure. The quantum dots are arranged and sized to emit light with specific intensity distributions at different angles, making the display visible only within a controlled viewing angle range and preventing peeping from oblique directions
Solution Approach 2:
The patent uses asymmetric emission patterns from the quantum dot layer to control viewing angles. The quantum dot size distribution and arrangement create an asymmetric light emission profile that is optimized for frontal viewing while suppressing emission at oblique angles, thereby preventing peeping
3Illumination intensity
If quantum dots with different peak wavelengths are used, then light intensity in off-normal directions is enhanced, but device complexity increases
Solution Approach 1:
The patent makes the quantum dot layer multi-functional by having it simultaneously perform light emission, viewing angle control, and peeping prevention functions. The quantum dots with different peak wavelengths serve multiple purposes: they enhance light intensity in off-normal directions while their specific size distribution and arrangement also control the viewing angle and prevent peeping, eliminating the need for separate liquid crystal layers
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 maintains high light intensity in normal viewing directions while significantly reducing visibility and recognizability of the image from oblique angles, effectively restricting peeping from such directions.
Implementation Method 1
a light-emitting layer between the first electrode and the second electrode, the light-emitting layer containing a first light-emitting material that emits first light that has a peak wavelength equal to a first wavelength and a second light-emitting material that emits second light that has a peak wavelength equal to a second wavelength
Implementation Method 2
a first electrode having a reflective surface that reflects light
Implementation Method 3
sin2(πD/λ2 represent intensity of light produced by interference of the reflection light and the direct light in the second light, and sin2(πDcos θ/λ2) represent intensity of light produced by interference of the reflection light and the direct light in the second light in the angle of inclination θ
Data Source
AI summary
A light-emitting element includes: a first electrode having a reflective surface that reflects light; a second electrode that transmits light; and a light-emitting layer between the first electrode and the second electrode, the light-emitting layer containing a first light-emitting material that emits first light that has a peak wavelength equal to a first wavelength and a second light-emitting material that emits second light that has a peak wavelength equal to a second wavelength shorter than the first wavelength, wherein the second light has at least one location where intensity is higher in a direction off a normal to the reflective surface than in the normal.