Transflective LCD Alignment Regulators for Disclination Control
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Solution Overview
Problem
Transflective liquid crystal display devices with vertical-alignment-type liquid crystals face challenges in achieving high brightness and wide viewing angles in both reflective and transmissive modes due to random inclination of liquid crystal molecules in reflective regions, leading to disclination and spotted patterns, especially when alignment regulators are used in narrow gaps.
Innovation Solution
A liquid crystal display device with a pair of substrates, a liquid crystal layer of negative dielectric anisotropy, a color filter layer, and alignment regulators on the substrates to control the inclination of liquid crystal molecules, using a multi-gap structure and non-colored regions in the color filter layer to adjust the thickness and alignment, ensuring proper alignment control in both reflective and transmissive regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If alignment regulators are provided in the reflective display region, then liquid crystal alignment is improved, but alignment disorder occurs due to the narrow gap
Solution Approach 1:
The patent applies different structural characteristics to different regions: the reflective display region has a smaller cell gap than the transmissive display region. This local differentiation allows alignment regulators to function effectively in the transmissive region while avoiding alignment disorder in the narrow-gap reflective region, as the regulators are either omitted or designed with different dimensions in the reflective region.
Solution Approach 2:
The display surface is divided into two distinct regions with different characteristics: reflective display regions with smaller cell gaps and transmissive display regions with larger cell gaps. This segmentation allows each region to be optimized independently, with alignment regulators selectively applied only where appropriate (transmissive regions) without causing harm to the reflective regions.
2Reliability
If a single polarizing plate is used in reflective mode, then parallax is prevented, but viewing angle is narrow in transmissive display
Solution Approach 1:
The patent creates different optical path configurations for different display modes by using a transflective plate with light-transmissive windows in the reflective display regions. This allows transmissive light to pass through the windows with different polarization control compared to reflective light paths, enabling wide viewing angle in transmissive mode while maintaining parallax prevention in reflective mode through the single polarizing plate configuration.
Solution Approach 2:
The transflective plate with selective light-transmissive windows acts as an intermediary structure that differentially controls light paths for reflective and transmissive modes. This intermediary element enables the system to achieve both parallax prevention (through single polarizing plate for reflective light) and wide viewing angle (through modified optical paths for transmissive light via the windows).
3Adaptability or versatility
If liquid crystal molecules are allowed to incline in random directions, then alignment flexibility is increased, but disclination and spotted patterns appear
Solution Approach 1:
The patent implements different alignment control strategies for different regions: in transmissive display regions, alignment regulators guide liquid crystal molecules to incline in specific radial directions from the center, while in reflective display regions, the smaller cell gap and absence of conventional alignment regulators result in different alignment behavior that is optimized for reflective mode, preventing disclination and spotted patterns in each respective region.
4Ease of manufacture
If the liquid crystal layer thickness is uniform, then manufacturing is simplified, but electro-optical characteristics differ between reflective and transmissive regions
Solution Approach 1:
The patent divides the liquid crystal layer into two distinct thickness regions: a first liquid crystal layer region over the reflective display region with a first thickness, and a second liquid crystal layer region over the transmissive display region with a second thickness. This segmentation allows each region to have optimized electro-optical characteristics appropriate for its display mode while maintaining a step-structured manufacturing process that, while slightly more complex than uniform thickness, achieves the required performance precision.
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 enables high-brightness, wide-viewing-angle displays with improved color reproducibility by controlling the inclination of liquid crystal molecules, reducing disclination and contrast issues, and maintaining visibility across various viewing angles.
Implementation Method 1
A 'VA (vertical alignment) mode' is used in which liquid crystal molecules having negative dielectric anisotropy are vertically aligned with respect to substrates in an initial state, and are then inclined when a voltage is applied
Implementation Method 2
liquid crystal molecules having negative dielectric anisotropy are vertically aligned with respect to substrates in an initial state
Implementation Method 3
external light incident on the upper substrate passes through the liquid crystal layer and is then reflected from the reflective film on the inner surface of the lower substrate. Then, the reflected light passes through the liquid crystal layer again to be emitted from the upper substrate
Implementation Method 4
in the transmissive mode, light emitted from a backlight to the lower substrate passes through the liquid crystal layer via the windows of the reflective film, and is then emitted from the upper substrate to the outside
Implementation Method 5
alignment regulators that are provided on an inner surface of at least one of the pair of substrates to regulate the alignment of the liquid crystal in the reflective display regions
Implementation Method 6
liquid crystal molecules having negative dielectric anisotropy are vertically aligned with respect to substrates in an initial state, and are then inclined when a voltage is applied
Data Source
AI summary
A liquid crystal display device includes a pair of substrate; a liquid crystal layer that is formed between the pair of substrates, and that is composed of liquid crystal having negative dielectric anisotropy, the liquid crystal being vertically aligned in an initial state; dot regions each having a transmissive display region and a reflective display region; a liquid-crystal-layer-thickness adjusting layer that is provided between the liquid crystal layer and at least one of the pair of substrates to make the thickness of the liquid crystal layer in the reflective display region smaller than the thickness of the liquid crystal layer in the transmissive display region; a color filter layer that includes plural types of colored layers having different colors corresponding to the respective dot regions, and that is provided on at least one of the pair of substrates; and alignment regulators that are provided on an inner surface of at least one of the pair of substrates to regulate the alignment of the liquid crystal in the reflective display regions. In the above-mentioned structure, a colored region having the colored layer formed therein and a non-colored region not having the colored layer formed therein are provided in a portion of the colored layer that is arranged in the reflective display region, and the alignment regulators are arranged so as to overlap the non-colored regions of the color filter layer in the reflective display regions in plan view.