Organic EL Display Tint Stabilization via Anisotropic Layer
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Solution Overview
Problem
Organic EL display devices using conventional polarizing plates experience a change in tint when viewed from an oblique direction, leading to unsatisfactory visual recognition of white displays.
Innovation Solution
Incorporating a light absorption anisotropic layer with a specific composition containing a liquid crystal compound and dichroic substance, aligned to control the angle between the transmittance central axis and the layer plane, and optimizing the phase difference and absorption anisotropy to suppress tint changes in white displays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a conventional circularly polarizing plate is used to suppress external light reflection, then the adverse effect due to external light reflection is suppressed, but the tint changes when white display is visually recognized from an oblique direction
Solution Approach 1:
The patent changes the optical parameters of the polarizing plate by controlling the phase difference (γ) to be 210° to 290° and the thickness of the retardation film to be 90 nm to 200 nm. These parameter adjustments optimize the plate's performance to suppress external light reflection while minimizing tint changes when viewed from oblique directions, resolving the contradiction between reflection suppression and tint stability.
Solution Approach 2:
The patent employs a composite structure consisting of a polarizing plate with multiple functional layers, including a retardation film and a circularly polarizing film. This composite design combines the advantages of different materials to achieve both effective suppression of external light reflection and maintenance of consistent tint across various viewing angles.
2Stability of the object's composition
If the phase difference and thickness of the polarizing plate are optimized to suppress tint changes, then the tint stability is improved, but the ability to suppress external light reflection may be reduced
Solution Approach 1:
The patent identifies optimal ranges for key parameters: phase difference γ of 210° to 290° and retardation film thickness of 90 nm to 200 nm. Within these ranges, the polarizing plate achieves a balanced performance that simultaneously suppresses external light reflection and maintains tint stability, resolving the trade-off between these two competing requirements.
Solution Approach 2:
The patent carefully controls the optical properties of the polarizing plate to minimize color shifts and tint changes when viewed from oblique directions. By optimizing the phase difference and thickness parameters, the plate maintains consistent color characteristics while still providing effective suppression of external light reflection.
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 stabilizes the tint in white displays when viewed from oblique directions, enhancing the visual consistency and quality of organic EL display devices.
Implementation Method 1
a light absorption anisotropic layer with a specific composition containing a liquid crystal compound and dichroic substance, aligned to control the angle between the transmittance central axis and the layer plane, and optimizing the phase difference and absorption anisotropy
Implementation Method 2
a composition containing a liquid crystal compound and a dichroic substance
Implementation Method 3
a light absorption anisotropic layer formed of a composition containing a liquid crystal compound and a dichroic substance, aligned to control the angle between the transmittance central axis and the layer plane
Data Source
AI summary
An organic EL display device capable of suppressing a change in tint in a case where white display is visually recognized from an oblique direction. The organic EL display device includes an organic EL display element and a light absorption anisotropic layer, in which the light absorption anisotropic layer is a light absorption anisotropic layer formed of a composition containing a liquid crystal compound and a dichroic substance, an angle between a transmittance central axis of the light absorption anisotropic layer and a normal line of a layer plane of the light absorption anisotropic layer is 0° or more and 450 or less, and A(λ) of the light absorption anisotropic layer represented by Expression (1) A(λ)={kz(λ)−(kx(λ)+ky(λ))/2}×d, is 15 to 225 nm at a maximal absorption wavelength of the light absorption anisotropic layer.