Transmittance Variable Device Oblique Contrast Ratio
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Solution Overview
Problem
Existing transmittance-variable devices experience deteriorated contrast ratios when observed at an oblique direction, particularly in applications like eyewear and augmented reality devices.
Innovation Solution
A transmittance-variable device comprising a double cell structure with superimposed GH layers and a phase difference element, where the GH layers consist of a liquid crystal compound and dichroic dye, allowing for high transmittance in a clear state and low transmittance in a black state, even when viewed obliquely, by controlling the orientation of the dichroic dye and utilizing a phase difference element with a λ/2 phase delay characteristic.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single GH cell structure is used, then the device is simple in structure, but the contrast ratio deteriorates when observed in an oblique direction
Solution Approach 1:
The device divides the single GH cell into multiple GH cells (first GH cell and second GH cell) with different optical axis orientations. Each GH cell is segmented to handle specific angular ranges, collectively covering a broader viewing angle range while maintaining high contrast ratio in each segment.
Solution Approach 2:
The invention introduces a new dimension by adding multiple GH cells with different optical axis orientations (e.g., 0° and 45°). This multi-dimensional arrangement in the optical axis space enables the device to maintain performance across oblique viewing angles that a single-oriented cell cannot achieve.
2Measurement precision
If multiple GH cells with different optical axis orientations are superimposed, then the contrast ratio in oblique direction is improved, but the device complexity increases
Solution Approach 1:
Multiple GH cells with different optical axis orientations are merged into a single integrated device structure. The cells are superimposed and work together as a unified system, sharing common electrodes and control mechanisms, which reduces overall complexity compared to separate devices.
Solution Approach 2:
Each GH cell in the superimposed structure serves multiple functions: it contributes to contrast ratio maintenance in its specific angular range while also participating in the overall transmittance modulation for the entire device. This multi-functionality reduces the need for additional specialized components.
3Ease of operation
If the optical axis of GH cell is parallel to the alignment direction, then the transmittance control is effective in vertical direction, but the contrast ratio deteriorates in oblique direction
Solution Approach 1:
The invention deliberately creates asymmetry by setting different optical axis orientations for different GH cells (e.g., 0° for first cell, 45° for second cell) relative to the alignment direction. This asymmetric configuration ensures that no single cell dominates in all directions, thereby maintaining contrast ratio across oblique viewing angles while preserving effective transmittance control.
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 device achieves a high contrast ratio in both vertical and oblique light conditions, ensuring effective transmittance adjustment and improved visibility in various applications, including eyewear and architectural materials.
Implementation Method 1
a transmittance-variable device using a so-called GH cell (guest host cell), to which a mixture of a host material, which is mainly a liquid crystal compound, and a dichroic dye guest is applied
Implementation Method 2
the orientation of the dichroic dye guest in the GH cell
Implementation Method 3
utilizing a phase difference element with a λ/2 phase delay characteristic
Implementation Method 4
a phase difference element disposed between the two GH layers
Data Source
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AI summary
The present application relates to a transmittance-variable device and a use thereof. The transmittance-variable device of the present application can switch between a clear state and a black state, can exhibit high transmittance in the clear state and a high shielding rate in the black state, and can exhibit a high contrast ratio even at the inclination angle. Such a transmittance-variable device of the present application can be applied to various applications including various architectural or automotive materials which need to adjust the transmittance, or eyewear such as goggles for augmented reality experience or sports, sunglasses or helmets.