Transparent Screen Hot Spot Reduction via Cholesteric Liquid Crystal
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Solution Overview
Problem
Transparent screens used in projection-type display systems suffer from a 'hot spot' issue, where the light source of the projector is glaringly visible on the opposite side of the screen, especially with high transparency and laser projectors, and existing solutions to reduce this issue compromise transparency.
Innovation Solution
A transparent screen configuration comprising a first λ/4 plate, a reflecting layer with immobilized cholesteric liquid crystalline phase, and a polarizing film with an absorption axis in the thickness direction, optionally with a second λ/4 plate and specifically arranged reflecting dots, to minimize hot spots while maintaining high transparency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If an uneven structure is imparted to the outermost surface of the transparent screen to diffuse light and reduce hot spots, then the hot spot is reduced, but the transparency significantly deteriorates
Solution Approach 1:
The invention divides the light diffusion function into discrete reflecting dots (cholesteric liquid crystal regions) distributed on the screen surface, rather than using a continuous uneven structure. Each dot reflects light in specific directions while leaving gaps between them for light transmission, thus reducing hot spots while maintaining transparency.
Solution Approach 2:
The cholesteric liquid crystal structure is applied locally in dot form rather than uniformly across the entire screen. This localized application allows specific regions to perform light diffusion while other regions maintain high transparency, resolving the contradiction between hot spot reduction and transparency preservation.
2Quantity of substance
If the transparency of the screen is increased to maintain high visibility, then the transparency is improved, but the hot spot becomes significantly glaring
Solution Approach 1:
The invention converts the harmful specularly reflected light that causes hot spots into a beneficial effect by using the cholesteric liquid crystal's natural reflection property. The same optical property that was causing the problem (light reflection) is harnessed in a controlled dot pattern to diffuse light and eliminate hot spots while preserving transparency.
3Object-affected harmful factors
If a reflecting layer with cholesteric liquid crystal structure is added to reduce hot spots, then the hot spot is reduced, but the device complexity increases
Solution Approach 1:
The invention uses a composite structure combining a transparent support substrate with a cholesteric liquid crystal layer containing reflecting dots. This composite material approach integrates the light diffusion function into the screen itself rather than adding separate components, thus reducing overall device complexity while maintaining hot spot reduction effectiveness.
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 effectively reduces the glaring 'hot spot' effect while maintaining high transparency and wide viewing angles by selectively reflecting and polarizing light, ensuring a clear image display without significant loss of transparency.
Implementation Method 1
a reflecting layer that has a structure obtained by immobilizing a cholesteric liquid crystalline phase and reflects a part of incidence light
Implementation Method 2
a first λ/4 plate; a second λ/4 plate that is provided between the reflecting layer and the polarizing film
Implementation Method 3
a polarizing film that has an absorption axis in a thickness direction
Data Source
AI summary
Provided are a transparent screen having high transparency in which a hot spot caused by transmitted light can be reduced; and an image display system in which visibility of a screen is excellent and a hot spot is reduced by using the transparent screen. The transparent screen includes, in this order: a first λ/4 plate; a reflecting layer that has a structure obtained by immobilizing a cholesteric liquid crystalline phase and reflects a part of incidence light; and a polarizing film that has an absorption axis in a thickness direction.