Optical Compensation Film Stack for OLED Viewing Angle Contrast
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Solution Overview
Problem
Organic light-emitting display devices suffer from reduced contrast ratio and light leakage due to external light reflection, which is exacerbated by misalignment of reflected light directions with the absorption axis of polarizing plates at various viewing angles, leading to image quality deterioration and color inversion.
Innovation Solution
Incorporation of an optical compensation film with stacked quarter-wave and half-wave plates to align reflected light with the polarizing layer's absorption axis, using continuous manufacturing to simplify the process and minimize defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a polarizing plate is introduced to prevent external light reflection, then contrast ratio is improved, but light leakage and color inversion occur at oblique viewing angles
Solution Approach 1:
The patent introduces an optical compensation film as an intermediary layer between the polarizing plate and the display panel. This film has specific optical properties (phase difference values) that compensate for the polarization angle changes occurring at oblique viewing angles, thereby preventing light leakage and color inversion while maintaining the contrast ratio improvement provided by the polarizing plate.
Solution Approach 2:
The patent utilizes optical compensation films with specific phase difference parameters (λ/4 and λ/2) to change the optical path difference of reflected light. By controlling these parameter values, the polarization state of light at oblique angles is adjusted to match the absorption axis of the polarizing plate, eliminating viewing angle defects while preserving contrast ratio.
2Adaptability or versatility
If multiple optical compensation films with different phase difference values are stacked, then viewing angle characteristics are improved, but manufacturing complexity increases
Solution Approach 1:
The patent combines multiple optical compensation films with different phase difference values (λ/4 and λ/2) into a single integrated structure. This merging approach maintains the optical compensation benefits for improved viewing angle characteristics while simplifying the manufacturing process by treating them as a unified component rather than separate assembly steps.
Solution Approach 2:
The stacked optical compensation film structure serves multiple functions simultaneously: it compensates for polarization angle changes at oblique viewing angles, maintains contrast ratio, and prevents light leakage. This multi-functionality is achieved through a single manufacturing process that forms both film types in sequence, reducing overall process 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
Prevents light leakage and color inversion, maintaining image quality across viewing angles while simplifying the manufacturing process and reducing manufacturing costs.
Implementation Method 1
when directions of the light reflected from the organic light-emitting display device and an absorption axis of the polarizing plate do not match with each other
Implementation Method 2
introducing an optical compensation film that orients a direction of light reflected from an organic light-emitting display device adjacent to or coincident with a direction of an absorption axis of a polarizing layer
Implementation Method 3
the optical compensation film has a structure with a first optical compensation film having a phase difference value of λ/4 of a wavelength of transmitted light and a second optical compensation film having a phase difference value of λ/2 of the wavelength of the transmitted light stacked with each other
Data Source
AI summary
A display device includes a substrate, an alignment film positioned on the substrate, a polarizing layer positioned on the alignment film, and an optical compensation film positioned between the substrate and the alignment film, wherein the optical compensation film has a structure with a first optical compensation film having a phase difference value of λ/4 of a wavelength of transmitted light and a second optical compensation film having a phase difference value of λ/2 of the wavelength of the transmitted light stacked with each other.