Display Light-Blocking Structure for Wide-Angle Tint Uniformity
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Solution Overview
Problem
Display devices using quantum dot light-emitting diodes (QLEDs) or organic light-emitting diodes (OLEDs) exhibit a tint difference when viewed from different angles due to interference between light beams, causing variations in light intensity and color perception.
Innovation Solution
A display device with multiple light-emitting layers and a light-blocking portion that blocks part of the light traveling in directions inclined to the reference direction, with specific layers emitting light of different peak wavelengths and varying ratios of blocked light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a thin film layered structure with light-emitting layers is used to achieve high brightness and color saturation, then light intensity is improved, but interference between light beams causes tint difference when viewed from different angles
Solution Approach 1:
The patent applies local quality by setting different charge transport layer thicknesses for different color regions (blue, green, red). Specifically, the blue light-emitting layer has a thickness of 50-150 nm, the green light-emitting layer has 100-200 nm, and the red light-emitting layer has 150-250 nm. This localized variation in thickness compensates for the wavelength-dependent interference effects, ensuring uniform tint across different viewing angles while maintaining high light intensity.
2Ease of manufacture
If the charge transport layer thickness is kept uniform across all light-emitting layers to simplify manufacturing, then ease of manufacture is improved, but light distribution characteristics vary among wavelengths causing color shift at inclined viewing angles
Solution Approach 1:
The patent implements local quality by differentiating the charge transport layer thickness for each color sub-pixel. The blue region uses 50-150 nm, green uses 100-200 nm, and red uses 150-250 nm. This localized customization addresses the viewing angle performance issue by compensating for wavelength-specific interference, while the overall process remains compatible with standard OLED manufacturing techniques.
Solution Approach 2:
The patent applies parameter changes by systematically varying the charge transport layer thickness parameter across different color regions. The thickness increases from blue (50-150 nm) to green (100-200 nm) to red (150-250 nm), creating a gradient that compensates for the increasing wavelength and its associated interference effects, thereby maintaining consistent color appearance across viewing angles.
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
Reduces the tint difference when viewing the display surface from different angles by controlling light intensity distribution, maintaining consistent color perception across viewing directions.
Implementation Method 1
a light-blocking portion configured to block part of light traveling from the light-emitting surface in directions inclined with respect to the reference direction
Implementation Method 2
two light beams emitted from a light-emitting layer interfere with each other. More specifically, interference occurs between a first light beam directly radiated to the outside from the light-emitting layer and a second light beam radiated to the outside after the first light beam emitted from the light-emitting layer reflects on an electrode
Data Source
AI summary
A display device includes a plurality of light-emitting layers each capable of emitting light in a reference direction orthogonal to a light-emitting surface, and a light-blocking portion capable of blocking part of light traveling from the light-emitting surface in directions inclined with respect to the reference direction. The plurality of light-emitting layers include a first light-emitting layer capable of emitting light with a first peak wavelength and a second light-emitting layer capable of emitting light with a second peak wavelength that is longer than the first peak wavelength. The first light-emitting layer has, compared with the second light-emitting layer, a large ratio of the part of light that can be blocked by the light-blocking portion to light traveling in at least one certain direction out of the inclined directions.