Laminate with Anisotropic Layers for Window Light Leakage Control
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Solution Overview
Problem
Existing light control systems for windows fail to effectively reduce brightness in all directions during the black display state, leading to light leakage issues.
Innovation Solution
A laminate comprising a first polarizer, a first patterned optical anisotropic layer, a second patterned optical anisotropic layer, and a second polarizer, with an optically anisotropic layer disposed between the second polarizer and the second patterned optical anisotropic layer, where the absorption axes of the polarizers are angled at 90°±5°, and the patterned layers have phase difference regions with alternating slow axis directions to optimize light transmission and blocking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a conventional light control system with polarizers and patterned optical anisotropic layers is used, then the device can switch between white and black display states, but the brightness of the black display state cannot be sufficiently reduced in the front and all directions due to light leakage
Solution Approach 1:
The patent introduces an optically anisotropic layer as an intermediary component between the second polarizer and the second patterned optical anisotropic layer. This layer has specific optical characteristics (Re_off(550) of 240 to 310 nm and Rth_off(550) of -50 to 50 nm at a wavelength of 550 nm in a direction of an azimuthal angle of 45° and a polar angle of 60° from a slow axis) that act as a mediator to control and reduce light leakage in oblique directions, thereby suppressing brightness in the black display state without compromising the switching function between display states.
2Illumination intensity
If the optical characteristics of the patterned layers are optimized to reduce black state brightness, then light leakage is reduced, but the complexity of the laminate structure increases
Solution Approach 1:
The patent applies parameter changes by precisely controlling the optical parameters of the optically anisotropic layer, specifically setting Re_off(550) between 240 to 310 nm and Rth_off(550) between -50 to 50 nm. By optimizing these numerical parameters, the patent achieves effective brightness control in the black display state while maintaining a manageable laminate structure, rather than adding more complex structural elements.
3Illumination intensity
If an optically anisotropic layer with specific characteristics is added to reduce light leakage, then brightness in black display state is reduced in all directions, but the device complexity increases
Solution Approach 1:
The patent applies local quality by positioning the optically anisotropic layer at a specific location within the laminate structure - between the second polarizer and the second patterned optical anisotropic layer. This strategic placement allows the layer to specifically address light leakage in oblique directions where it matters most, achieving uniform brightness control in the black display state without unnecessarily increasing overall device complexity throughout the entire structure.
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 enables a seamless switch between white and black display states with minimized light leakage in all directions, particularly in the front and oblique off-axis directions, enhancing privacy and energy efficiency.
Implementation Method 1
a first polarizer, a first patterned optical anisotropic layer, a second patterned optical anisotropic layer, and a second polarizer in this order... an angle formed between an absorption axis of the first polarizer and an absorption axis of the second polarizer is 90°±5°
Implementation Method 2
each of the first patterned optical anisotropic layer and the second patterned optical anisotropic layer includes first phase difference regions and second phase difference regions which have different slow axis directions
Implementation Method 3
the optically anisotropic layer has an Re_off(550) of 240 to 310 nm at a wavelength of 550 nm in a direction of an azimuthal angle of 45° and a polar angle of 60° from a slow axis of the optically anisotropic layer, and has an Rth_off(550) of −50 to 50 nm
Data Source
AI summary
Provided is a laminate including a first polarizer, a first patterned optical anisotropic layer, a second patterned optical anisotropic layer, and a second polarizer in this order and an optically anisotropic layer disposed between the second polarizer and the second patterned optical anisotropic layer, in which an angle formed between an absorption axis of the first polarizer and an absorption axis of the second polarizer is 90°±5°; each of the first patterned optical anisotropic layer and the second patterned optical anisotropic layer has a plurality of phase difference regions having different slow axis directions in a plane of the first patterned optical anisotropic layer or the second patterned optical anisotropic layer; a white display state and a black display state are switched with each other; none of the slow axis directions of first phase difference regions and the slow axis directions of second phase difference regions are parallel or orthogonal to the absorption axes and transmission axes of the two sheets of polarizers; and the optically anisotropic layer has Re_off(550) of 240 to 310 nm and Rth_off(550) of −50 to 50 nm. Also provided is a window.