Active Viewing Angle Control in OLED Displays
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Solution Overview
Problem
Conventional organic light-emitting display devices require the attachment and detachment of privacy films to switch between wide and narrow viewing angles, which is inconvenient for users.
Innovation Solution
An organic light-emitting display device with a viewing angle control layer comprising a liquid crystal layer and a control electrode, where the control electrode includes a plate electrode and protruding tip electrodes, allowing for active control of the viewing angle by applying or removing voltage, and a λ/4 phase retardation layer to suppress reflected light visibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a privacy film is fixedly attached on the display panel to achieve narrow viewing angle mode, then privacy protection is improved, but the device complexity and ease of operation deteriorate due to the need for attaching and detaching the film for mode switching
Solution Approach 1:
The patent applies a liquid crystal layer that can dynamically change its optical properties based on applied voltage. In the off state, the liquid crystal molecules are vertically aligned allowing wide viewing angles. In the on state, the molecules reorient to provide narrow viewing angles for privacy protection. This dynamic switching eliminates the need for physical attachment and detachment of privacy films, resolving the contradiction between adaptability and ease of operation.
2Adaptability or versatility
If a privacy film is attached to achieve narrow viewing angle mode, then viewing angle control is improved, but the device complexity increases due to additional components and attachment processes
Solution Approach 1:
The patent merges the privacy protection function directly into the display panel structure by integrating a liquid crystal layer between the organic light-emitting element and the front surface. This integration combines the display function with the viewing angle control function, eliminating the need for separate privacy films and their associated attachment mechanisms, thereby reducing device complexity while maintaining adaptability.
3Adaptability or versatility
If conventional privacy film is used for viewing angle control, then privacy mode is achieved, but reflected light visibility is not suppressed
Solution Approach 1:
The patent employs a composite structure consisting of an organic light-emitting element combined with a liquid crystal layer and specific optical compensation layers. This composite material approach allows simultaneous achievement of viewing angle control and suppression of reflected light visibility. The liquid crystal layer's optical anisotropy, combined with the organic light-emitting element's emission characteristics, creates a system that controls both viewing angle and reflected light properties, addressing the harmful effect of visible reflected light while maintaining privacy protection functionality.
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
Enables convenient switching between wide and narrow viewing angles without the need for privacy films, while reducing visibility of reflected light.
Implementation Method 1
a liquid crystal layer including positive c-plate liquid crystal molecules aligned vertically
Implementation Method 2
a λ/4 phase retardation layer disposed thereon, such that the visibility of the reflected light according to the viewing angle may be suppressed
Data Source
AI summary
A display device includes a viewing angle control layer including a liquid crystal layer disposed on a second electrode of an organic light-emitting element and the control electrode disposed on the liquid crystal layer, the control electrode includes a plate electrode and a plurality of tip electrodes protruding from the plate electrode toward the second electrode, wherein the plurality of tip electrodes are arranged within a light-emitting area of the organic light-emitting element, and the liquid crystal layer includes positive c-plate liquid crystal molecules aligned vertically.