Silicone Adhesive Polarization Conversion Element Heat Resistance
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Solution Overview
Problem
Polarization conversion elements in liquid crystal display devices face durability issues due to the degradation of UV curing-type adhesives and polymer-based retardation plates under high brightness conditions, leading to reduced transmittance and mechanical weakness, especially under heat and light exposure.
Innovation Solution
A polarization conversion element is designed using a polarizing beam splitter array bonded with silicone-based adhesives and an inorganic ½ wavelength plate with an obliquely deposited dielectric film, which enhances heat and light resistance by converting P-wave to S-wave or vice versa, and includes a protective film to maintain optical characteristics and bond strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a UV curing-type adhesive is used for bonding polarizing beam splitters and prisms, then the initial bonding strength is sufficient, but the adhesive quickly deteriorates with heat and light causing burning and concentration of irradiation light
Solution Approach 1:
The patent changes the chemical composition parameter of the adhesive from UV-curing type to silicone-based adhesive. This material substitution fundamentally alters the thermal and optical stability parameters, enabling the adhesive to withstand high temperatures and UV light without deterioration, thus resolving the durability issue while maintaining bonding strength
Solution Approach 2:
The patent employs a composite structure where silicone-based adhesive is used in combination with the polarizing beam splitters and prisms. This composite material approach creates a system with enhanced overall durability, as the silicone-based adhesive provides resistance to heat and light while maintaining adequate bonding properties
2Ease of operation
If a dichroic retardation plate with polymer stretched film is used, then the retardation function is achieved, but the plate easily deteriorates with heat and UV light and contracts
Solution Approach 1:
The patent changes the material parameter of the retardation plate from polymer-based to inorganic material. This substitution fundamentally improves thermal stability and UV resistance, eliminating the deterioration and contraction issues while maintaining the necessary retardation optical function
Solution Approach 2:
The patent replaces the mechanically stretched polymer film structure with an inorganic retardation plate. This substitution eliminates the mechanical contraction problem inherent in stretched films while achieving the same optical retardation effect through different physical mechanisms
3Ease of operation
If a polyvinyl alcohol-based film is used for the retardation plate, then the retardation function is achieved, but the film is easily deformed under humidified conditions and mechanical strength is weakened
Solution Approach 1:
The patent changes the hydrophilic parameter of the retardation plate material from hydrophilic (polyvinyl alcohol) to hydrophobic (inorganic material). This parameter change eliminates the deformation issue under humidified conditions while maintaining the retardation function and significantly improving mechanical strength
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 significantly improves the durability and resistance to heat and light, extending the lifespan of the polarization conversion element by at least ten times compared to traditional UV adhesive-based elements, while allowing for larger sizes and lower material costs.
Implementation Method 1
a polarization separation layer that transmits one of a P wave and a S wave and reflects the other
Implementation Method 2
a reflecting layer that reflects the other of the P wave or the S wave reflected from the polarization separation layer
Implementation Method 3
an inorganic 1/2 wavelength plate having an obliquely deposited film composed of a dielectric material so that one of the P-wave and the S-wave is converted to the other
Data Source
AI summary
This invention provides a polarization conversion element that is highly resistant to the heat and light that result from increased brightness levels. In said polarization conversion element, which is provided with a polarizing beam-splitter array in which polarizing beam splitters having polarization separation layers and reflecting prisms having reflective layers are bonded together in alternation, said polarizing beam splitters and reflecting prisms are bonded together by first adhesive layers each comprising a silicone adhesive.