Cholesteric Liquid Crystal Dot Optical Member for Pen Input
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Solution Overview
Problem
Existing optical members for data input using electronic pens have limited sensitivity due to the cholesteric structure's circularly polarization selective reflection, which only reflects either right or left circularly polarized light, resulting in reduced intensity of reflected light and scattered light rather than increased intensity.
Innovation Solution
A novel optical member with a substrate and dots made of liquid crystal material having a cholesteric structure that reflects both right and left circularly polarized light, enhancing the intensity of reflected light and improving data input sensitivity by using a layered state of cholesteric structures with right and left helical twist directions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a cholesteric structure with distributed inclination angles is used, then a wide reading angle is achieved, but the intensity of reflected light is not increased (light is scattered instead)
Solution Approach 1:
The invention divides the single cholesteric structure into multiple dot-shaped cholesteric structures with different inclination angles. Each dot acts as an independent reflecting unit, and collectively they provide both wide reading angle and high reflected light intensity through constructive interference, resolving the contradiction between scattering (wide angle) and intensity concentration.
Solution Approach 2:
Different regions (dots) of the optical member have different local properties - each dot has a specific inclination angle optimized for its position. This local differentiation allows each dot to reflect light efficiently while collectively covering a wide reading angle, achieving both high intensity and wide adaptability.
2Measurement precision
If circularly polarization selective reflection is used, then SN ratio is improved, but absolute intensity of reflected light is not increased
Solution Approach 1:
The invention combines multiple dot-shaped cholesteric structures with different helical twist directions (right-handed and left-handed) in the same optical member. This merging allows simultaneous reflection of both right and left circularly polarized lights, increasing the absolute intensity of reflected light while maintaining the SN ratio improvement through polarization selectivity.
Solution Approach 2:
The optical member uses a composite structure combining multiple cholesteric liquid crystal dots with different properties (different inclination angles, different helical twist directions) on a substrate. This composite arrangement enables both high reflected light intensity and good polarization selectivity, resolving the contradiction between SN ratio improvement and absolute intensity.
3Manufacturing precision
If dot diameter is reduced for finer handwriting data input, then resolution is improved, but intensity of reflected light from each dot decreases
Solution Approach 1:
The invention optimizes multiple parameters of the dot-shaped cholesteric structures, including inclination angle, helical twist direction, and dot size, to achieve the best balance between dot fineness and reflected light intensity. By carefully controlling these parameters, the patent maintains high resolution while ensuring sufficient light reflection from each small dot.
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 optical member increases data input sensitivity by reflecting both circularly polarized lights, leading to stronger and more intense reflected light, improving the signal-to-noise ratio and enhancing the data input capability.
Implementation Method 1
the dot is made of a liquid crystal material having a cholesteric structure; the dot has wavelength selective reflection property; and the dot reflects both the right circularly polarized light and the left circularly polarized light at a wavelength at which the dot exhibits the wavelength selective reflection property
Implementation Method 2
this liquid crystal material has a circularly polarization selective reflection property in which only either of the right circularly polarized light or the left circularly polarized light is reflected
Data Source
AI summary
The present invention provides an optical member having a substrate and a dot in contact with a surface of the substrate, wherein the dot is made of a liquid crystal material having a cholesteric structure; the dot has wavelength selective reflection property; and the dot reflects both the right circularly polarized light and the left circularly polarized light at a wavelength at which the dot exhibits the wavelength selective reflection property. The present invention also provides an image display device having the above optical member. The optical member of the present invention achieves a large intensity of reflected light from the dot in the optical member, and the image display device of the present invention has favorable data input sensitivity as an image display device capable of receiving data input.