Double-Sided TFT Cholesteric LCD Alignment
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Solution Overview
Problem
Cholesteric liquid crystal display devices face challenges in aligning and laminating two-color cholesteric liquid crystal layers with high precision, leading to color mixing and blurred image quality, which requires advanced and costly equipment.
Innovation Solution
A double-sided Thin Film Transistor (TFT) structure on the same substrate eliminates the need for precise alignment, as TFTs can be integrated on both sides of the substrate, allowing two-color pixel alignment during the lithography etching stage without additional high-precision equipment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional separate TFT structures are used on different substrates, then each TFT can be independently manufactured, but precise alignment between the two substrates requires advanced and costly equipment
Solution Approach 1:
The patent merges two separate TFT structures onto a single substrate, creating a double-sided TFT configuration where both TFT circuits are integrated on the same substrate rather than requiring separate substrates. This integration eliminates the need for precise alignment between separate substrates during lamination, as both TFTs are already positioned relative to each other on the same substrate.
Solution Approach 2:
The patent utilizes the third dimension (z-axis) by fabricating TFT circuits on both the front and back surfaces of the same substrate. This dimensional approach allows the two TFT structures to coexist without requiring planar alignment precision, as they are separated by the substrate thickness rather than requiring lateral alignment.
2Manufacturing precision
If high-precision alignment equipment is used to align two-color cholesteric liquid crystal layers, then color mixing is prevented, but equipment investment costs increase
Solution Approach 1:
By integrating both TFT circuits on a single substrate, the patent eliminates the need for separate substrate alignment equipment. The two-color pixel alignment is achieved through the inherent positioning of the TFT structures on the same substrate, removing the requirement for expensive high-precision alignment equipment.
Solution Approach 2:
The patent employs standard lithography etching processes that are already widely available in semiconductor manufacturing, replacing the need for specialized high-precision alignment equipment. This approach uses existing, more affordable manufacturing capabilities to achieve the alignment function.
3Manufacturing precision
If additional alignment steps with high-precision equipment are performed, then two-color pixel alignment is improved, but manufacturing process complexity increases
Solution Approach 1:
The patent combines the alignment function into the substrate integration process itself. By fabricating both TFT circuits on the same substrate using standard lithography, the alignment is achieved as an inherent part of the manufacturing process rather than requiring separate alignment steps.
Solution Approach 2:
The alignment of the two TFT circuit pattern layers is accomplished during the lithography etching stage, before subsequent manufacturing steps. This preliminary alignment action is built into the fabrication process, eliminating the need for later alignment operations.
Data Source
AI summary
A cholesteric liquid crystal display device includes a first substrate, a second substrate, a third substrate, a first cholesteric liquid crystal layer, a second cholesteric liquid crystal layer, a first common electrode pattern layer, a second common electrode pattern layer, and a first TFT circuit pattern layer and the second TFT circuit pattern layer. The first cholesteric liquid crystal layer is disposed between the first substrate and the second substrate. The second cholesteric liquid crystal layer is disposed between the second substrate and the third substrate. The first common electrode pattern layer is disposed on the first substrate. The second common electrode pattern layer is disposed on the third substrate. The first TFT circuit pattern layer and the second TFT circuit pattern layer are respectively disposed on two opposite surfaces of the second substrate. The first TFT circuit pattern layer and the second TFT circuit pattern layer are arranged correspondingly. As a result, alignment can be accomplished without the use of high-precision equipment.