Homeotropic LCD with Thickness Adjusting Layer
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Solution Overview
Problem
Homeotropic alignment liquid crystal display devices face issues with display unevenness due to non-uniform liquid crystal molecule alignment and cannot perform reflective displays, leading to reduced aperture ratio and quality differences between transmissive and reflective displays.
Innovation Solution
A liquid crystal display device with a reflective layer and a liquid crystal layer thickness adjusting layer allows for both transmissive and reflective displays by controlling liquid crystal molecule alignment, using a pair of substrates with pixel electrodes, thin film transistors, and homeotropic alignment films, and dividing each pixel electrode into portions for separate display regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If X-shaped openings are formed in the opposing electrode to create multiple alignment domains, then the alignment state is stabilized and view angle characteristic is improved, but the aperture ratio is reduced due to increased opening area
Solution Approach 1:
The pixel electrode is divided into multiple electrode portions (first, second, third electrode portions) arranged in a matrix pattern. This segmentation creates multiple alignment domains without requiring large X-shaped openings, as each electrode portion independently controls liquid crystal alignment in its region, thereby maintaining high aperture ratio while achieving stable alignment and wide view angle characteristics.
2Ease of manufacture
If the liquid crystal layer thickness is uniform across the pixel, then the manufacturing process is simple, but display unevenness occurs due to non-uniform liquid crystal molecule alignment
Solution Approach 1:
The pixel electrode is divided into multiple electrode portions with different potential control capabilities. By applying different potentials to each electrode portion, the liquid crystal alignment can be locally optimized in different regions of the pixel. This local control enables uniform display quality across the entire pixel area while maintaining a uniformly thick liquid crystal layer, avoiding the need for complex thickness variation in manufacturing.
3Adaptability or versatility
If a reflective layer is added to enable reflective display, then the device can perform both reflective and transmissive displays, but the device complexity increases
Solution Approach 1:
The liquid crystal display device incorporates a reflective layer in the substrate structure, enabling it to perform both reflective display (using ambient light) and transmissive display (using backlight) functions. The same liquid crystal layer and electrode structure control both display modes, achieving multi-functionality without requiring separate display systems. This allows the device to adapt to different lighting conditions and application requirements while maintaining a relatively compact and integrated structure.
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
Enables stable liquid crystal molecule alignment and improved display quality by allowing reflective and transmissive displays with reduced quality differences, maintaining a high aperture ratio and enhancing image precision and luminance.
Implementation Method 1
a liquid crystal layer having negative dielectric anisotropy, which is sealed between the pair of substrates
Implementation Method 2
a homeotropic alignment film is formed on the internal surface of each of the pair of substrates
Implementation Method 3
the liquid crystal molecules of each pixel are aligned to lie down toward the substrate surface from the homeotropically aligned state
Implementation Method 4
a reflective layer formed on the internal surface of the substrate, of the pair of substrates, that is at an opposite side to an observer side, for forming, in each of the plurality of pixels, a reflective display region for reflecting light that enters from the observer side to the observer side
Data Source
AI summary
A liquid crystal display device has a pair of substrates disposed at an observer side and at the opposite side to the observer side, a plurality of pixel electrodes and an opposing electrode which are formed on the internal surfaces of the pair of substrates, a reflective layer, and liquid crystal sealed between these substrates. Each pixel electrode has a reflective display region corresponding to the reflective layer for reflecting light that enters from the observer side to the observer side, and a transmissive display region for allowing light that enters from the opposite side to pass therethrough to the observer side. A liquid crystal layer thickness adjusting layer is formed on the internal surface of the substrate at the observer side, for setting the liquid crystal layer thickness in the reflective display region to be smaller than the liquid crystal layer thickness in the transmissive display region.