Liquid Crystal Display Protective Plate Retardation Control
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Solution Overview
Problem
Existing liquid crystal display protective plates suffer from deterioration in visibility due to rainbow unevenness, blackout, and coloring when viewed through a polarizing filter, primarily due to variations in the in-plane retardation value (Re value) caused by stress and birefringence.
Innovation Solution
A liquid crystal display protective plate is designed with a resin plate structure that includes a phase difference adjusting layer with specific optical properties, such as a transparent thermoplastic resin (A) with a low photoelastic coefficient and controlled orientation birefringence, laminated on both sides by a substrate layer with a higher glass transition temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a resin plate with high birefringence is used to adjust the Re value, then the Re value can be controlled within a suitable range, but the visibility deteriorates due to rainbow unevenness and coloring when viewed through a polarizing filter
Solution Approach 1:
The patent changes the material parameter by selecting a resin with a specific photoelastic coefficient range (50 to 200×10^-12 m^2/N), which allows control of the Re value while minimizing birefringence-induced visibility deterioration. This parameter optimization resolves the contradiction between achieving suitable Re value control and preventing rainbow unevenness and coloring when viewed through polarizing filters.
Solution Approach 2:
The patent employs a laminated structure comprising a resin plate and a phase difference adjusting layer with different optical properties. The resin plate provides mechanical strength and baseline optical properties, while the phase difference adjusting layer fine-tunes the Re value. This composite approach enables precise Re value control without requiring high birefringence materials, thereby preventing visibility deterioration.
2Stability of the object's composition
If the Re value is increased to adjust optical properties, then the phase difference can be controlled, but the light transmittance difference for each wavelength increases causing colored phenomenon
Solution Approach 1:
The patent optimizes the photoelastic coefficient parameter of the resin to a specific range (50 to 200×10^-12 m^2/N) that enables sufficient Re value adjustment while maintaining low birefringence. This parameter selection ensures that the phase difference can be controlled without creating large wavelength-dependent transmittance differences, thereby preventing colored phenomenon when viewed through polarizing filters.
3Illumination intensity
If a polarizing filter is used to view the screen, then the polarization property can be observed, but the visibility deteriorates due to blackout phenomenon
Solution Approach 1:
The patent selects resins with optimized photoelastic coefficients (50 to 200×10^-12 m^2/N) that minimize stress-induced birefringence. This parameter optimization ensures that when light passes through the resin plate and a polarizing filter, the polarization state is not significantly altered by internal stresses, thereby preventing blackout phenomenon while still allowing polarization observation.
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
This configuration effectively suppresses the deterioration of visibility by maintaining a stable Re value, reducing rainbow unevenness and blackout, and improving image clarity when observed through a polarizing filter.
Implementation Method 1
a transparent thermoplastic resin (A) having an absolute value of photoelastic coefficient (CA) of 10.0 × 10^-12 to 50.0 × 10^-12
Implementation Method 2
controlled orientation birefringence
Data Source
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AI summary
The present invention provides a liquid crystal display protective plate capable of suppressing deterioration of visibility such as rainbow unevenness, blackout, and coloring when the liquid crystal display protective plate on a liquid crystal screen is observed through a polarizing filter. The liquid crystal display protective plate (1) of the present invention includes a resin plate (16) in which a substrate layer (22) is laminated on both sides of a phase difference adjusting layer (21). The phase difference adjusting layer includes a transparent thermoplastic resin (A) having an absolute value of the photoelastic coefficient of 10.0 × 10-12/Pa or less and an absolute value of orientation birefringence of 10.0 × 10-4 to 100.0 × 10-4. The substrate layer includes a transparent thermoplastic resin (B) having an absolute value of the photoelastic coefficient of 10.0 × 10-12/Pa or less and an absolute value of orientation birefringence of less than 10.0 × 10-4. Tg of the substrate layer is higher than Tg of the phase difference adjusting layer. The resin plate has a Re value of 50 to 330 nm.