Switchable Viewing Angle LCD via Pretilt Angle Control
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Solution Overview
Problem
Conventional liquid crystal displays (LCDs) with wide viewing angles fail to protect user privacy in public settings, as they cannot easily switch to a narrow viewing angle without using inconvenient louver shielding films or costly dual light source backlight systems, which increase thickness and cost.
Innovation Solution
An LCD design that includes a first and second substrate with a liquid crystal layer, where the liquid crystal molecules are tilted at specific pretilt angles, allowing the viewing angle to be controlled by applying a bias voltage to the first electrode, switching between narrow and wide viewing angles without the need for additional films or dual light sources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a louver shielding film is used to cover the screen, then the viewing angle is reduced to protect privacy, but the device complexity and cost increase due to additional components
Solution Approach 1:
The patent extracts the privacy protection function from external accessories (louver films) and integrates it into the liquid crystal display's core structure by configuring specific pretilt angles in the liquid crystal molecules, thereby eliminating the need for additional shielding components
Solution Approach 2:
The liquid crystal display achieves privacy protection through its own internal structure configuration (specific pretilt angle settings), making the system self-sufficient without requiring external louver films or additional shielding mechanisms
2Adaptability or versatility
If a dual light source backlight system is provided, then the viewing angle can be switched between narrow and wide, but the thickness and cost of the LCD increase remarkably
Solution Approach 1:
The patent changes the optical parameters of the liquid crystal molecules by configuring specific pretilt angles (first pretilt angle and second pretilt angle with same magnitude but contrary direction) to achieve viewing angle switching without adding physical layers or light sources
Solution Approach 2:
The liquid crystal layer with specifically configured pretilt angles serves multiple functions: it provides both wide viewing angle display and narrow viewing angle privacy protection modes, eliminating the need for separate optical components for each function
3Adaptability or versatility
If a dual light source backlight system is provided, then the viewing angle can be adjusted, but the cost of the LCD increases
Solution Approach 1:
The patent extracts the viewing angle control function from complex dual light source systems and implements it through simple liquid crystal molecular orientation configuration, significantly reducing manufacturing complexity and cost
Solution Approach 2:
The patent uses the existing liquid crystal material and alignment film structure to achieve viewing angle switching, replacing expensive dual light source systems with a cost-effective molecular orientation approach
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 easy switching between narrow and wide viewing angles by adjusting the liquid crystal molecule tilt, improving image contrast and privacy protection without increasing the LCD's thickness or cost, while maintaining flexibility and ease of operation.
Implementation Method 1
When a bias voltage is applied to the first electrode, a vertical electric field is generated between the first substrate and the second substrate to cause the liquid crystal molecules of the liquid crystal layer to rotate
Implementation Method 2
The liquid crystal molecules adjacent to the first alignment film are tilted at a first pretilt angle relative to the first alignment film. The liquid crystal molecules adjacent to the second alignment film are tilted at a second pretilt angle relative to the second alignment film
Data Source
AI summary
An LCD with switchable viewing angle includes a first substrate, second substrate, and a liquid crystal layer. The first substrate is provided with a first electrode and a first alignment film. The second substrate is provided with a second electrode, a third electrode and a second alignment film. The liquid crystal molecules adjacent to the first alignment film are tilted at a first pretilt angle. The liquid crystal molecules adjacent to the second alignment film are tilted at a second pretilt angle. The first pretilt angle and the second pretilt angle have the same magnitude but are contrary in direction. When no bias voltage is applied to the first electrode, the LCD is displayed with a narrow viewing angle; and when a bias voltage is applied to the first electrode, the LCD is displayed with a wide viewing angle.