Cholesteric Liquid Crystal Display Panel With Gradient Polymer
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Solution Overview
Problem
Cholesteric liquid crystals with short pitches used in transmissive displays face issues of high driving voltage, narrow viewing angle, and low alignment stability.
Innovation Solution
A display panel is manufactured with cholesteric liquid crystals having a pitch shorter than a visible ray wavelength, where a polymer is added and its concentration is controlled by light exposure, creating a gradient across the substrates to reduce driving voltage and improve viewing angle and contrast ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If cholesteric liquid crystals with short pitch are used in transmissive displays, then the display can be used in transmissive type, but the driving voltage becomes high
Solution Approach 1:
The patent applies local quality by creating a gradient distribution of polymer concentration within the liquid crystal layer. The polymer concentration varies from the first substrate to the second substrate, with higher concentration near one substrate and lower concentration near the other. This non-uniform distribution allows different regions to have different properties, enabling the system to achieve both short pitch for transmissive display and reduced driving voltage through optimized local characteristics.
2Adaptability or versatility
If cholesteric liquid crystals with short pitch are used, then transmissive display is enabled, but the viewing angle becomes narrow
Solution Approach 1:
The gradient polymer distribution creates regions with different alignment characteristics. This spatial variation in polymer concentration helps to broaden the viewing angle by compensating for the narrow viewing angle issue inherent in short pitch cholesteric liquid crystals, while maintaining the transmissive display capability.
3Adaptability or versatility
If cholesteric liquid crystals with short pitch are used, then transmissive display is enabled, but the alignment stability becomes low
Solution Approach 1:
The patent changes the parameter of polymer concentration distribution from uniform to gradient. By controlling the polymer concentration to vary spatially within the liquid crystal layer, the alignment stability is improved. The gradient distribution creates a more stable alignment configuration that prevents the low alignment stability problem associated with short pitch cholesteric liquid crystals in transmissive displays.
4Stability of the object's composition
If polymer concentration is increased to improve alignment stability, then alignment stability improves, but the driving voltage increases
Solution Approach 1:
Instead of uniformly increasing polymer concentration throughout the layer, the patent applies local quality by creating a gradient distribution. This allows polymer to be concentrated in regions where it provides maximum alignment stability benefit while minimizing its impact on driving voltage. The spatially varying concentration optimizes the trade-off between alignment stability and driving voltage.
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 lowers the driving voltage and enhances display quality by stabilizing the alignment of cholesteric liquid crystals and improving the contrast ratio and viewing angle.
Implementation Method 1
A concentration of the polymer in the cholesteric liquid crystal is controlled by exposing the polymer to a light
Implementation Method 2
An electric field is generated between the first and second electrodes
Implementation Method 3
shortening the pitch of the cholesteric liquid crystals may control birefringence resulting from the intensity of the electric field
Data Source
AI summary
A display panel includes a first substrate and a second substrate facing the first substrate. The second substrate includes a first electrode and a second electrode spaced apart from each other. A cholesteric liquid crystal having a pitch shorter than a wavelength of a visible ray and a rotation axis substantially perpendicular to the first and second substrates is disposed between the first and second substrates. The display panel displays a grayscale image in response to an electric field generated between the first and second electrodes. A polymer is added to the cholesteric liquid crystal, and a concentration of the polymer is controlled by exposing the polymer to a light. The concentration of the polymer in an area adjacent to the first substrate may be higher than the concentration of the polymer in an area adjacent to the second substrate.