Transparent Screen Cholesteric Liquid Crystal Dots Viewing Angle
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Solution Overview
Problem
Transparent screens that reflect light from the front surface and transmit light from the back surface face challenges in achieving both high transparency and a wide viewing angle, as increasing diffusibility to widen the viewing angle leads to increased haze and reduced transparency, while enhancing transparency narrows the viewing angle.
Innovation Solution
A transparent screen comprising a substrate with dots formed of liquid crystal material having a cholesteric structure, which provides wavelength-selective reflectivity and a striped pattern, with a portion having a height that increases continuously to the center, and an overcoat layer with a refractive index difference of 0.10 or less, allowing for selective reflection and transmission of light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If diffusibility is increased to widen the viewing angle, then the viewing angle is improved, but the haze value increases and transparency is lowered
Solution Approach 1:
The screen is divided into multiple dot-shaped reflective elements arranged in an array. Each dot independently reflects light, and the collective arrangement provides both diffusion for wide viewing angles and localized reflection that maintains transparency. The segmentation allows light to pass through the spaces between dots while still providing reflective functionality.
Solution Approach 2:
Different regions of the screen have different optical properties. The dot-shaped elements provide reflective functionality in specific locations, while the spaces between dots maintain transparency. This local differentiation allows simultaneous achievement of wide viewing angle through the reflective dots and high transparency through the transparent regions.
2Object-generated harmful factors
If transparency is increased, then the transparency is improved, but the viewing angle is narrowed due to mirror reflection behavior
Solution Approach 1:
The screen is divided into multiple dot-shaped reflective elements arranged in an array. Each dot independently reflects light, and the collective arrangement provides both diffusion for wide viewing angles and localized reflection that maintains transparency. The segmentation allows light to pass through the spaces between dots while still providing reflective functionality.
Solution Approach 2:
The reflective elements are arranged in a two-dimensional array pattern rather than being distributed uniformly. This spatial arrangement in multiple dimensions allows the screen to provide wide viewing angles through the patterned distribution of reflective dots while maintaining overall transparency through the transparent regions between the dots.
3Illumination intensity
If a cholesteric liquid crystal structure is used for wavelength-selective reflection, then the reflection performance is improved, but the manufacturing complexity increases
Solution Approach 1:
The pitch of the cholesteric liquid crystal helix structure is controlled to match specific wavelengths of light for selective reflection. By adjusting this physical parameter, the screen can be tuned to reflect desired wavelengths (such as blue, green, or red light) while transmitting other wavelengths, providing wavelength-selective reflection functionality.
Solution Approach 2:
The screen combines cholesteric liquid crystal material with a transparent substrate and protective overcoat layer. This composite structure integrates the wavelength-selective reflection property of the cholesteric liquid crystal with the transparency and mechanical stability of the substrate, achieving both optical performance and manufacturability.
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 transparent screen with excellent transparency and a wide viewing angle by reflecting light in various directions while maintaining high transmittance, effectively addressing the trade-off between transparency and viewing angle in existing technologies.
Implementation Method 1
a plurality of dots formed on a surface of the substrate, the dots having wavelength-selective reflectivity and being formed of a liquid crystal material having a cholesteric structure
Implementation Method 2
liquid crystal material having a cholesteric structure, in which the cholesteric structure gives a striped pattern of bright parts and dark parts
Implementation Method 3
an overcoat layer covering the dots on the surface of the substrate on the side where the dots have been formed, wherein the difference between the refractive index of the overcoat layer and the refractive index of the dots is 0.10 or less
Implementation Method 4
A diffusion type screen uniformly diffuses and reflects light that has hit the surface into all directions without deflection
Implementation Method 5
A mirror reflection type screen reflects light such that the incident angle of light is equal to the reflected angle
Data Source
AI summary
A transparent screen includes a substrate capable of transmitting light; and a plurality of dots formed on a surface of the substrate, each of the dots having wavelength-selective reflectivity and being formed of a liquid crystal material having a cholesteric structure, in which the cholesteric structure gives a striped pattern of bright parts and dark parts in a cross-sectional view of the dot observed by scanning electron microscope, the dot includes a portion having a height that increases continuously to the maximum height in a direction extending from the edge toward the center of the dot, and in the portion, the angle formed by the normal line to a line that is formed by a first one of the dark parts as counted from the surface of the dot on the opposite side of the substrate and the surface of the dot is in the range of 70° to 90°.