TN Liquid Crystal Viewing Angle Control for Directional Display Brightness
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Solution Overview
Problem
Existing image display apparatuses struggle to achieve high brightness in the front direction and low brightness in oblique directions at specific azimuthal angles, particularly when applied in vehicle environments.
Innovation Solution
A viewing angle control system comprising a specific configuration of polarizers and liquid crystal cells, including TN-mode liquid crystal cells, optical compensation layers, and immobilized tilt-aligned or hybrid-aligned liquid crystal compounds, to control light emission angles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional display devices are used, then images can be observed from desired directions, but it is difficult to observe images from other directions and viewing angle control is insufficient
Solution Approach 1:
The display device is divided into multiple functional layers: a display unit, a first viewing angle control unit with first liquid crystal layer and first polarizer, and a second viewing angle control unit with second liquid crystal layer and second polarizer. Each layer performs a specific function in controlling the viewing angle, allowing independent optimization of each segment to achieve comprehensive viewing angle control while maintaining image observability from multiple directions.
2Illumination intensity
If optical systems are designed for high brightness in front direction, then front viewing brightness is improved, but brightness in oblique directions cannot be sufficiently controlled
Solution Approach 1:
The patent applies different optical compensation strategies to different spatial regions. The first and second optical compensation layers are configured with specific retardation values and orientation angles that are optimized for different viewing zones. The first viewing angle control unit primarily controls brightness in the front direction, while the second viewing angle control unit specifically addresses brightness in oblique directions, allowing localized optimization of brightness characteristics for different viewing angles.
3Object-generated harmful factors
If viewing angle control is enhanced to reduce light leakage in oblique directions, then brightness control is improved, but device complexity increases
Solution Approach 1:
The patent introduces optical compensation layers as intermediary elements between the display unit and the viewing angle control units. These compensation layers with specific retardation values serve as mediators that adjust the polarization state of light passing through the liquid crystal layers, enabling effective viewing angle control and light leakage reduction. By using these intermediary optical elements, the patent achieves comprehensive viewing angle control without requiring overly complex liquid crystal cell structures.
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 system effectively achieves high brightness in the front direction and low brightness in oblique directions, enhancing visibility from desired angles while reducing light leakage.
Implementation Method 1
a first liquid crystal cell and a second liquid crystal cell which are TN-mode liquid crystal cells
Implementation Method 2
the first optical compensation layer is a layer where, in a case where a retardation is measured from a normal direction of the first optical compensation layer and a direction tilted from the normal direction of the first optical compensation layer, the retardation is at a minimum in the direction tilted from the normal direction of the first optical compensation layer
Implementation Method 3
the first optical compensation layer is a layer where, in a case where a retardation is measured from a normal direction of the first optical compensation layer and a direction tilted from the normal direction of the first optical compensation layer, the retardation is at a minimum in the direction tilted from the normal direction of the first optical compensation layer
Data Source
AI summary
A viewing angle control system includes sequentially: a first polarizer, a first optical compensation layer, a first TN-mode liquid crystal cell, a second polarizer, a second TN-mode liquid crystal cell, a second optical compensation layer, and a third polarizer. The first and second optical compensation layers each exhibit minimum retardation in a tilted direction rather than in a normal direction. The system provides high brightness in a front direction and low brightness in an oblique direction at a specific azimuthal angle when applied to a light source.