Switchable View Angle Control LCD for Automotive Privacy Displays
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Solution Overview
Problem
Conventional liquid crystal display (LCD) devices that switch between narrow and wide angle view modes often require additional backlights, increasing thickness and cost, and suffer from insufficient view angle control, particularly in applications like automotive displays.
Innovation Solution
A novel liquid crystal switchable scattering layer that can be electrically switched between a transparent non-scattering state and a scattering state, enhancing off-axis light control by rotating the polarization of off-axis light and scattering it when necessary, thereby improving view angle control without the need for additional optical layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a second backlight is added to enable wide angle view mode, then viewing angle is improved, but device thickness and cost increase
Solution Approach 1:
The patent combines the wide angle view control function with the existing single backlight unit by using a light control film positioned between the backlight and display panel. This merges multiple functions (backlighting and view angle control) into a single integrated structure, eliminating the need for a separate second backlight and thereby reducing device thickness while maintaining wide angle viewing capability
Solution Approach 2:
The patent introduces a light control film as an intermediary element between the backlight unit and the display panel. This light control film acts as a mediator that manipulates light propagation angles without requiring additional backlight sources, thus achieving wide angle view mode while avoiding the thickness penalty of adding another backlight unit
2Adaptability or versatility
If a second backlight is added to enable wide angle view mode, then viewing angle is improved, but device cost increases
Solution Approach 1:
The patent merges the view angle control function with the existing backlight system using a light control film, eliminating the need for a costly second backlight unit. This integration reduces component count and assembly complexity, thereby lowering manufacturing costs while achieving wide angle viewing capability
Solution Approach 2:
The patent employs a light control film that is less expensive than a full second backlight unit. This film-based solution provides the necessary wide angle view control at a lower cost point, making the overall device more cost-effective while maintaining the required viewing angle performance
3Adaptability or versatility
If out-of-plane reorientation of liquid crystal is used for view angle control, then viewing angle is improved, but liquid crystal performance as image panel is reduced
Solution Approach 1:
The patent segments the liquid crystal system into two distinct functional parts: a view angle control liquid crystal layer that handles angle control through out-of-plane reorientation, and a display liquid crystal layer that maintains optimal image quality. This segmentation allows each layer to be optimized for its specific function without compromising the other, thus achieving wide angle viewing while preserving image panel performance
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 provides an enhanced private mode with strong off-axis light screening while maintaining a high-quality public mode, reducing the need for secondary backlights and improving view angle control, thus addressing the deficiencies of conventional configurations.
Implementation Method 1
the polarization of off-axis light is rotated. When the off-axis light then reaches the next polarizer, which can be on cell, in cell, or on the image panel, the off-axis light is absorbed by the front polarizer
Implementation Method 2
The scattering state can be achieved either by the application or removal of a bias voltage, which induces a director configuration within the liquid crystal where there are discontinuities in the refractive index encountered by a light ray
Implementation Method 3
the off-axis light is absorbed by the front polarizer
Data Source
AI summary
A switchable view angle control device for a privacy view display system includes an electrically switchable view angle control LCD that is operable in a first state and a second state; a front polarizer located on a viewing side of the switchable view angle control LCD; and a polarized light source located on a non-viewing side of the switchable view angle control LCD that emits polarized light. When the switchable view angle control LCD in the first state, the view angle control device operates in a narrow angle view mode in which off-axis polarized light from the polarized light source is changed by the switchable view angle control LCD so that the off-axis light is absorbed by the front polarizer, and on-axis light passes through the switchable view angle control LCD and the front polarizer. When the switchable view angle control LCD is in the second state, the view angle control device operates in a wide angle view mode in which the polarized light from the polarized light source is scattered by the switchable view angle control LCD and passes through the front polarizer.