OLED Color Filter Wavelength Band Optimization
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Solution Overview
Problem
Organic light emitting display devices face reduced luminous efficiency and contrast due to external light reflection and absorption by polarizing layers, leading to increased optical losses and blue shift in emission spectra as viewing angles change.
Innovation Solution
Incorporating a color filter with an expanded transmission wavelength band towards shorter wavelengths, specifically tailored for each organic light emitting element, to compensate for optical losses and maintain luminance across varying viewing angles, along with a black matrix with varying taper angles and separation distances to optimize side luminance ratios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a linear polarizing plate is used to suppress external light reflection, then outdoor visibility is improved, but luminous efficiency is reduced due to absorption of emitted light
Solution Approach 1:
The patent removes the linear polarizing plate from the display device structure entirely, extracting the harmful component that causes both external light reflection and luminous efficiency loss. Instead, it uses a circular polarizing plate which handles light differently, allowing it to maintain anti-reflection properties while preserving more of the emitted light for display purposes.
Solution Approach 2:
The patent changes the polarization state parameter from linear to circular. By using a circular polarizing plate that converts linearly polarized light into circularly polarized light, the device maintains the ability to suppress external light reflection while allowing more of the emitted light to pass through, thereby improving luminous efficiency compared to traditional linear polarizing plates.
2Loss of energy
If a color filter is introduced to replace the polarizing layer, then luminous efficiency is improved, but transmission wavelength band is reduced
Solution Approach 1:
The patent merges the functions of the color filter and the circular polarizing plate into a single integrated structure. The circular polarizing plate is positioned within the color filter layer, allowing it to perform both wavelength selection (color filtering) and polarization conversion simultaneously. This integration ensures that the color filter's transmission wavelength band is not reduced, as the polarizing function is added without blocking additional wavelengths.
Solution Approach 2:
The circular polarizing plate serves multiple functions: it converts linearly polarized light to circularly polarized light, suppresses external light reflection, and maintains the transmission characteristics of the color filter. By making the polarizing component multi-functional, the patent avoids the trade-off between luminous efficiency and transmission wavelength band that would occur with separate components.
3Adaptability or versatility
If viewing angle increases, then side luminance ratio changes, but blue shift in emission spectra causes luminance differences
Solution Approach 1:
The patent introduces a resonance structure with adjustable optical path length that can dynamically adapt to different viewing angles. By changing the optical path length within the resonance cavity, the device compensates for the blue shift that occurs at oblique viewing angles, maintaining consistent luminance across different viewing directions and reducing luminance differences caused by angle-dependent spectral shifts.
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 effectively reduces luminance differences and maintains display quality by minimizing optical losses and blue shift, enhancing the viewing angle performance of organic light emitting display devices.
Implementation Method 1
a color filter on the organic light emitting elements, wherein a transmission wavelength band of the color filter has an upper limit value for transmitting a light wavelength corresponding to a first intensity of a light emitted from the organic light emitting elements at a viewing angle of about 0°, and has a lower limit value for transmitting a light wavelength corresponding to a second intensity that is less than the first intensity
Implementation Method 2
an organic light emitting display device (e.g., organic light emitting diode (OLED) display device) is a self-luminous display in which an organic compound is electrically excited to emit light
Implementation Method 3
a black matrix with varying taper angles and separation distances to optimize side luminance ratios
Data Source
AI summary
An organic light emitting display device includes a first substrate, a second substrate opposite from the first substrate, a plurality of organic light emitting elements on the first substrate, and a color filter on the organic light emitting elements, wherein a transmission wavelength band of the color filter has an upper limit value for transmitting a light wavelength corresponding to a first intensity of a light emitted from the organic light emitting elements at a viewing angle of about 0°, and has a lower limit value for transmitting a light wavelength corresponding to a second intensity that is less than the first intensity.