Optical Laminate for In-Vehicle Display Glare Reduction
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Solution Overview
Problem
Image display devices, such as in-vehicle navigation systems, face issues with reflected glare due to insufficient light shielding properties in oblique directions, leading to image reflection on peripheral members like windshields or window glasses.
Innovation Solution
An optical laminate comprising a first and second light absorption anisotropic layer with dichroic substances, each having a transmittance central axis at 0° to 45° from the normal, and λ/2 wavelength retardation layers with a 45°±10° slow axis angle, providing excellent light transmission in one direction and effective light shielding in all other directions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single light absorption anisotropic layer is used, then the structure is simple, but light shielding properties in oblique directions are insufficient
Solution Approach 1:
The optical laminate divides the light control function into multiple segments: first and second light absorption anisotropic layers for directional light absorption, and first and second retardation layers for polarization control. This segmentation allows each layer to contribute to specific aspects of light management, achieving comprehensive glare reduction while maintaining structural organization
Solution Approach 2:
The patent employs composite material structures by combining light absorption anisotropic layers containing dichroic substances with retardation layers having specific retardation values. This composite approach integrates materials with different optical properties to achieve both excellent light transmission in the front direction and effective shielding in oblique directions
2Object-affected harmful factors
If light shielding properties in oblique directions are enhanced, then reflected glare is reduced, but light transmission in the front direction may be compromised
Solution Approach 1:
The optical laminate applies local quality by configuring each layer with specific optical properties tailored to its function. The light absorption anisotropic layers are oriented to absorb light from oblique directions while transmitting front-direction light, and the retardation layers are positioned to control polarization states selectively, ensuring that each region of the laminate contributes to the overall performance without compromising the other
Solution Approach 2:
The patent utilizes parameter changes by adjusting the retardation values of the retardation layers and the orientation angles of the light absorption anisotropic layers. By optimizing these parameters, the system achieves excellent light transmission in the front direction (0° to 45° from normal) while effectively shielding oblique directions, thus resolving the contradiction between transmission and shielding
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 optical laminate ensures excellent light transmission in a specific direction while effectively shielding light in all other directions, reducing image reflection on peripheral surfaces.
Implementation Method 1
the first retardation layer and the second retardation layer are λ/2 wavelength plates, an angle formed between a slow axis of the first retardation layer and a slow axis of the second retardation layer is within a range of 45°±10°
Implementation Method 2
the first light absorption anisotropic layer and the second light absorption anisotropic layer contain a dichroic substance
Data Source
AI summary
An optical laminate having excellent light transmitting properties is used for an image display device, includes in order: a first light absorption anisotropic layer; first and second retardation layers; and a second light absorption anisotropic layer, in which the first and second retardation layers are λ/2 wavelength plates, an angle formed between a slow axis of the first and second retardation layers is within a range of 45°±10°, the first and the second light absorption anisotropic layers contain a dichroic substance, an angle formed between a transmittance central axis of the first light absorption anisotropic layer and a normal direction of a surface thereof is 0° or more and 45° or less, and an angle formed between a transmittance central axis of the second light absorption anisotropic layer and a normal direction of a surface thereof is 0° or more and 45° or less.