Twist-Aligned Liquid Crystal Display with Parallax Barrier
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Solution Overview
Problem
Liquid crystal display apparatuses with parallax barrier systems face issues of crosstalk, where display images overlap due to incomplete isolation, especially in multi-screen setups, leading to degraded contrast ratios and visibility when viewed from slanted angles, and existing solutions either complicate circuit configurations or increase costs.
Innovation Solution
A liquid crystal display apparatus with a twist-aligned TN mode liquid crystal layer, paired with linear polarizers and a parallax barrier layer, where the liquid crystal layer is twist-aligned by about 90° and has a Δnd value of 300-400 nm, and the polarizing axes of the linear polarizers are set to be substantially parallel or vertical to the liquid crystal molecules, with an angle between them of 85-90°, to reduce crosstalk and enhance contrast ratio in slanted visual fields without requiring multiple parallax barrier layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a parallax barrier layer is used to display multiple images to different observers, then multi-screen display capability is improved, but crosstalk between images increases and contrast ratio deteriorates
Solution Approach 1:
The patent applies parameter changes by optimizing the Δnd value of the liquid crystal layer to 300-400 nm and setting the polarizer angle to 85-90 degrees. These specific parameter adjustments control the light modulation characteristics to reduce crosstalk while maintaining multi-screen display functionality. The parameter optimization ensures that light from different pixel groups is properly directed to respective observers without excessive mixing.
Solution Approach 2:
The patent employs dynamic control through the liquid crystal layer that can change its optical properties in response to applied voltages. By dynamically switching the liquid crystal molecules between aligned and tilted states, the system controls light transmission and polarization to direct different images to different observers, reducing crosstalk through active optical modulation rather than static structural separation.
2Illumination intensity
If the polarizer angle is set to reduce crosstalk in slanted viewing angles, then visibility in desired visual fields is improved, but contrast ratio at frontal viewing angles deteriorates
Solution Approach 1:
The patent optimizes the polarizer angle parameter to a specific range of 85-90 degrees rather than using the conventional 45 degrees. This parameter change shifts the polarization configuration to favor slanted viewing angles while maintaining acceptable contrast at frontal angles. The optimization balances the trade-off by selecting an angle that maximizes visibility in the intended viewing direction.
Solution Approach 2:
The patent applies local quality by optimizing optical parameters specifically for slanted viewing angles rather than attempting to optimize for all viewing angles uniformly. The liquid crystal layer and polarizer configuration are tuned to provide superior performance in the desired slanted visual fields, accepting that contrast ratio may be compromised at frontal viewing angles which are less critical for this application.
3Object-affected harmful factors
If multiple parallax barrier layers are used to reduce crosstalk, then image isolation is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent extracts the crosstalk reduction function from the parallax barrier layer structure and transfers it to the liquid crystal layer and polarizer configuration. Instead of adding multiple parallax barrier layers to achieve image isolation, the invention uses the liquid crystal's optical modulation capabilities combined with optimized polarizer angles to provide sufficient isolation between multiple images, thereby simplifying the overall structure.
Solution Approach 2:
The patent replaces the mechanical approach of stacking multiple physical barrier layers with an optical field-based solution using liquid crystal modulation and polarizer configuration. This substitution eliminates the need for complex multi-layer barrier structures by using controllable optical properties of the liquid crystal layer to achieve image separation, reducing device complexity and manufacturing cost.
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 reduces crosstalk, maintains high contrast ratios, and provides excellent visibility in desired slanted visual fields without complicating the circuit configuration or increasing costs, improving display properties by minimizing image mixing and maintaining high luminance levels.
Implementation Method 1
the liquid crystal layer is twist-aligned when no electric field is applied, and has a Δnd value of 300 nm or larger and 400 nm or smaller
Implementation Method 2
Δnd value being a product of a refractive anisotropy Δn and a thickness of a liquid crystal layer d
Implementation Method 3
a pair of linear polarizers that are arranged outside the pair of substrates, each of the linear polarizers selectively transmitting specific linearly-polarized light
Implementation Method 4
A liquid crystal display apparatus of parallax barrier system with multi screen that includes a parallax barrier layer in a viewing side of a liquid crystal panel
Data Source
AI summary
In a liquid crystal display apparatus in which a liquid crystal layer is twist-aligned when no electric field is applied, Δnd value of a liquid crystal layer in a wavelength of 550 nm is 300 to 400 nm, each of directions of polarizing axes of pair of linear polarizers is substantially parallel or vertical to the alignment direction of liquid crystal molecules in each end face of the liquid crystal layer that is closer to each of linear polarizers, and the angle between polarizing axes of the pair of linear polarizers is 85° or larger and smaller than 90°. In a liquid crystal display apparatus in which a liquid crystal layer is aligned to be substantially vertical when no electric field is applied, the angle between polarizing axes of the pair of linear polarizers is 85° or larger and smaller than 90°. In a liquid crystal display apparatus of a lateral electric field drive system, a uniaxial alignment angle of a liquid crystal layer when no electric field is applied is larger than −45° and −40° or smaller, or +40° or larger and smaller than +45°.