Viewing Angle Control Film Using Intersecting Phase Difference Plates
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Solution Overview
Problem
Existing viewing angle control technologies, such as louver films and composite polarizing plates, fail to effectively narrow the viewing angle in all directions while maintaining sufficient brightness, as they either physically block light or are limited to specific viewing directions.
Innovation Solution
A viewing angle control film comprising a first polarizer with an absorption axis perpendicular to the film surface, a first λ/4 phase difference plate with a patterned optical anisotropic layer, and a second λ/4 phase difference plate with a patterned optical anisotropic layer, where the patterned layers have constant phase differences and are divided into belt-like regions with intersecting slow axes, allowing for 360° viewing angle control without significant brightness degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If a louver film is used to narrow the viewing angle, then the viewing angle is reduced, but the brightness of the screen in the front direction is degraded
Solution Approach 1:
The patent replaces the mechanical light-blocking structure of louver films with an optical system consisting of a vertically aligned polarizer and phase difference plates. This optical system controls light transmission through polarization effects rather than physical obstruction, thereby maintaining front-direction brightness while achieving viewing angle control.
Solution Approach 2:
The patent utilizes phase difference plates with specific retardation values (λ/4 plates) to modify the polarization state of light. By controlling the phase difference between ordinary and extraordinary rays, the system can selectively transmit or block light based on viewing angle without degrading front-direction brightness.
2Shape
If multiple louver layers are laminated to narrow the viewing angle in all directions, then the viewing angle is reduced in 360°, but the brightness degradation is further worsened
Solution Approach 1:
The vertically aligned polarizer combined with phase difference plates serves multiple functions simultaneously: it controls viewing angle in all directions (360°) and maintains front-direction brightness. This single optical system replaces the need for multiple louver layers, achieving universal viewing angle control without compounding brightness degradation.
3Shape
If a composite polarizing plate is used, then the viewing angle is narrowed in specific directions, but the viewing angle cannot be narrowed in all directions of 360°
Solution Approach 1:
The patent employs a composite optical system consisting of a vertically aligned polarizer and phase difference plates with specific optical properties. This composite structure achieves omnidirectional (360°) viewing angle control, overcoming the limitation of conventional composite polarizing plates that only control specific directions.
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 film effectively narrows the viewing angle in all directions while preserving front-direction brightness, preventing unauthorized viewing by absorbing light in oblique directions without physically blocking it, thus enhancing privacy in electronic devices.
Implementation Method 1
a first polarizer in which an absorption axis is in a direction perpendicular to a film surface
Implementation Method 2
a first phase difference plate which is a λ/4 plate and has a patterned optical anisotropic layer; and a second phase difference plate which is a λ/4 plate and has a patterned optical anisotropic layer
Implementation Method 3
the patterned optical anisotropic layer of the first phase difference plate and the patterned optical anisotropic layer of the second phase difference plate each have a constant phase difference and are divided into a plurality of belt-like regions in the same plane, directions of slow axes of one belt-like region match each other and directions of slow axes of belt-like regions adjacent to each other are different from each other
Data Source
AI summary
A viewing angle control film includes, in order, a first polarizer in which an absorption axis is in a direction perpendicular to a film surface; a first phase difference plate which is a λ/4 plate and has a patterned optical anisotropic layer; and a second phase difference plate which is a λ/4 plate and has a patterned optical anisotropic layer, in which the patterned optical anisotropic layers have a constant phase difference and are divided into a plurality of belt-like regions in the same plane, directions of slow axes in one belt-like region match each other and directions of slow axes of belt-like regions adjacent to each other are different from each other in the patterned optical anisotropic layer, and the belt-like region of the first phase difference plate and the belt-like region of the second phase difference plate are disposed so as to intersect with each other in a plane direction.