Polarizing Plate UV Absorber Modulus for LED Protection
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Solution Overview
Problem
Existing polarizing plates for light emitting displays fail to effectively suppress damage from external light, particularly in the UV range, leading to reduced reliability and increased power consumption due to inadequate UV absorption and transmittance properties, and may suffer from separation or bubbling under high temperature and humidity conditions.
Innovation Solution
A polarizing plate with a structure comprising a polarizing film, a first adhesive layer containing a UV absorber with a maximum absorption wavelength of 370 nm or higher, a retardation layer, and a third adhesive layer, which provides low transmittance in the 400-405 nm range while maintaining high transmittance in the 440-450 nm range, and has a modulus suitable to prevent separation and bubbling under extreme conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a UV absorber with maximum absorption wavelength of 370 nm or higher is used, then UV damage suppression is improved, but transmittance in the blue region (440-450 nm) may be reduced
Solution Approach 1:
The patent applies local quality by selecting a UV absorber with specific absorption characteristics (maximum absorption wavelength of 370 nm or higher) that targets only the harmful UV region while maintaining high transmittance in the blue region (440-450 nm). This localized spectral selectivity allows the absorber to protect against UV damage without interfering with the useful blue light transmission, thus resolving the contradiction between UV protection and power consumption.
Solution Approach 2:
The patent utilizes parameter changes by optimizing the maximum absorption wavelength parameter of the UV absorber to be 370 nm or higher. This specific parameter setting ensures that the absorber's absorption band is positioned to cover the harmful UV region while leaving the blue region (440-450 nm) sufficiently transparent, thereby achieving both UV protection and acceptable power consumption characteristics.
2Reliability
If adhesive layers with high modulus are used to prevent separation and bubbling, then reliability under high temperature and humidity is improved, but manufacturing complexity increases
Solution Approach 1:
The patent applies parameter changes by specifying precise modulus ranges for the adhesive layers at different temperatures (5×10^4 to 1×10^6 Pa at 80°C and 1×10^5 to 3×10^6 Pa at 30°C). These quantified parameter specifications provide clear design criteria that simplify the manufacturing process while ensuring the adhesive layers have sufficient mechanical properties to prevent separation and bubbling under high temperature and humidity conditions.
Solution Approach 2:
The patent employs composite materials by using multiple adhesive layers with different modulus characteristics optimized for different temperature conditions. The first adhesive layer (between polarizing film and retardation layer) and third adhesive layer (between retardation layer and substrate) are designed as a composite system where each layer's modulus is tailored to its specific functional requirements, achieving reliable bonding without excessive structural complexity.
3Object-affected harmful factors
If light transmittance in the 400-405 nm range is reduced to suppress UV damage, then protection against external light is improved, but light transmittance in the blue region (440-450 nm) must be maintained
Solution Approach 1:
The patent applies local quality by implementing spectral selectivity through the UV absorber that creates different transmittance characteristics in different wavelength regions. Specifically, the absorber reduces transmittance in the harmful 400-405 nm range while maintaining high transmittance (35% or higher) in the useful blue region (440-450 nm). This localized spectral control allows simultaneous achievement of UV protection and adequate blue light transmission.
Solution Approach 2:
The patent utilizes color changes (spectral transmission characteristics) by selecting a UV absorber that exhibits specific absorption properties at different wavelengths. The absorber's maximum absorption at 370 nm or higher creates a spectral profile that blocks harmful UV wavelengths while allowing blue light to pass through, effectively using optical property variations to resolve the transmittance contradiction.
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 polarizing plate effectively suppresses damage to light emitting diodes by reducing UV-induced transmittance loss, prolongs the lifespan of the diodes, and prevents increase in power consumption by maintaining high transmittance in the blue region, while ensuring reliability by preventing separation and bubbling under high temperature and humidity.
Implementation Method 1
a UV absorber having a maximum absorption wavelength of 370 nm or higher
Data Source
AI summary
A polarizing plate includes a polarizing film, a first adhesive layer or a bonding layer, a retardation layer, and a third adhesive layer, and includes: a UV absorber comprising an indole UV absorber, a phenylbenzotriazole UV absorber, and/or a triazine UV absorber, wherein the UV absorber has a maximum absorption wavelength of 370 nm or higher, the polarizing plate has a light transmittance of 5% or less in a wavelength range of about 400 nm to about 405 nm and a light transmittance of 35% or higher in a wavelength range of about 440 nm to about 450 nm, the first adhesive layer has a modulus of 1×105 Pa or higher at 80° C. and a modulus of 1×105 Pa or higher at 30° C., and the third adhesive layer has a modulus of 5×104 Pa to 1×106 Pa at 80° C. and a modulus of 1×105 Pa to 3×106 Pa at 30° C.