Switchable Polarizer for OLED External Light Reflection
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Solution Overview
Problem
Conventional OLED displays face issues with external light reflection, leading to poor black color expression and contrast, especially in bright environments, due to the reflection of external light by electrodes and metal wires, and existing solutions using polarizing and phase retardation plates result in significant optical loss.
Innovation Solution
An OLED display structure incorporating a substrate with organic light emitting diodes, a selective reflection layer, a phase retardation film, a twisted nematic liquid crystal layer, and linear polarizing films, where the liquid crystal molecules orientation is controlled by an electric field to manage external light polarization and minimize reflection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If polarizing and phase retardation plates are provided on the OLED to suppress external light reflection, then black color expression and contrast are improved, but optical loss of light generated by the organic emissive layer increases
Solution Approach 1:
The patent employs a switchable linear polarizer that can dynamically change between transparent non-polarizing state and transparent linear polarizing state. This dynamic switching capability allows the system to adapt to different operating conditions: when OLED pixels are emitting light, the polarizer is in transparent state to minimize optical loss; when pixels are off, the polarizer switches to polarizing state to suppress external light reflection and enhance contrast.
Solution Approach 2:
The invention changes the optical parameters of the polarizing film by switching between different polarization states. The switchable linear polarizer modifies its optical properties (from non-polarizing to linear polarizing) based on the emission state of the OLED, thereby optimizing both contrast ratio and light transmission efficiency under different operating conditions.
2Illumination intensity
If conventional polarizing plates are used to suppress external light reflection, then visibility in bright areas is improved, but much light generated by the organic emissive layer is eliminated
Solution Approach 1:
The switchable linear polarizer dynamically adjusts its polarization state based on whether the OLED pixel is emitting light or not. When the pixel is on, the polarizer remains transparent to maximize light transmission and visibility. When the pixel is off, the polarizer activates to suppress external light reflection, thereby improving visibility in bright environments without sacrificing light transmission when needed.
Solution Approach 2:
The invention extracts only the necessary polarization function when needed, rather than continuously applying polarization. By switching the polarizer on only when external light suppression is required (when pixels are off), the system eliminates unnecessary light transmission losses while maintaining visibility enhancement when it matters most.
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 suppresses external light reflection, enhancing visibility and minimizing optical loss, allowing for improved contrast and black color expression while maintaining efficient light emission.
Implementation Method 1
a twisted nematic liquid crystal layer arranged on the first linear polarizing film
Implementation Method 2
light produced by the respective organic light emitting diode and linearly polarized by passing through the first linear polarizing film can transparently pass through the twisted nematic liquid crystal layer
Implementation Method 3
a phase retardation film arranged on the selective reflection layer
Implementation Method 4
a selective reflection layer arranged on the organic light emitting diodes
Implementation Method 5
an organic light emitting diode (OLED) display is a self emissive display device that displays images using organic light emitting diodes
Data Source
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AI summary
An organic light emitting diode display (101) includes a substrate main body (111), an organic light emitting diode (70) including a first electrode (710), an organic emissive layer (720), and a second electrode (730) sequentially arranged on the substrate main body (111), a selective reflection layer (580) arranged on the organic light emitting diode (70), a phase retardation film (570) arranged on the selective reflection layer (580), a first linear polarizing film (560) arranged on the phase retardation film (570), a twisted nematic liquid crystal layer (550) arranged on the first linear polarizing film (560), a liquid crystal driving electrode (230) arranged on the twisted nematic liquid crystal layer (550) and a second linear polarizing film (510) arranged on the liquid crystal driving electrode (230).