Transparent Sheet with Curved Cholesteric Liquid Crystal Pattern
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Solution Overview
Problem
Existing transparent sheets for coordinate input on display devices have limited read angles, leading to reduced sensitivity and precision when the input pen is tilted, as they rely on a specific orientation of the cholesteric liquid crystal layer which only detects retroreflective components in the 0° direction.
Innovation Solution
A pattern-printed transparent sheet with a multilayer membrane structure having a fixed repeating cycle and curved parts, featuring a primer layer that repels ink and exhibits selective reflectivity to infrared or ultraviolet light, allowing for broad read angles by reflecting either circularly polarized light components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a cholesteric liquid crystal layer with vertical helical axis orientation is used for coordinate input, then the structure provides a simple retroreflective reading mechanism, but the read angle is limited to 0° and sensitivity is dramatically reduced when the input pen inclines
Solution Approach 1:
The patent introduces a curved portion to the multilayer membrane structure, where the membrane surface is curved rather than flat. This curvature allows the structure to reflect light from multiple angles, expanding the read angle from 0° only to a broad range including oblique directions, while maintaining the retroreflective functionality
Solution Approach 2:
The patent transitions from a two-dimensional flat membrane structure to a three-dimensional curved membrane structure. By adding the dimensional aspect of curvature, the structure can interact with light incident from various angles, thereby expanding the read angle without significantly increasing structural complexity
2Ease of manufacture
If a flat multilayer membrane structure with parallel plane surfaces is used, then the manufacturing process is simple, but the read angle is limited and detection precision is reduced when the pen is tilted
Solution Approach 1:
By curving the multilayer membrane structure, the patent enables the structure to maintain high detection precision across a broader range of incident angles. The curved surface ensures that light reflected from any angle within the expanded read angle can be effectively detected, preserving measurement precision without requiring complex flat surface alignment
3Stability of the object's composition
If the helical axis of the cholesteric liquid crystal is oriented vertically throughout the plain surface, then the structure is uniform and easy to produce, but only the retroreflective component in the 0° direction can be detected
Solution Approach 1:
The patent applies local quality by introducing curvature to specific regions of the multilayer membrane structure. Different portions of the curved membrane have different orientations relative to incident light, allowing the structure to detect light from multiple angles while maintaining the uniform helical axis orientation within each local region of the cholesteric liquid crystal
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 provides a transparent sheet with a broad read angle, enhancing the precision and sensitivity of coordinate detection by enabling reading of input lines across a wider range of angles, improving the accuracy of coordinate input systems.
Implementation Method 1
The property of reflecting an infrared ray by the transparent pattern in the present invention makes preferably use of, as described above, a wavelength selective reflectivity (the same principle as Bragg reflection in X-ray diffraction) of a liquid crystal material having a cholesteric structure
Implementation Method 2
the transparent pattern comprises a multilayer structure comprising a fixed repeating cycle and having a curved part and reflect selectively either of a left circularly polarized light component and a right circularly polarized light component in an incident light
Data Source
AI summary
A non-visible light reflective pattern-printed transparent sheet having a broad read angle is provided. The above transparent sheet is a pattern-printed transparent sheet in which a transparent substrate comprises a base material and a primer layer, and a non-visible light reflective transparent pattern is printed on the surface of the primer layer; an ink constituting the transparent pattern described above contains a material having a wavelength selective reflectivity to a wavelength in an infrared or ultraviolet region; the primer layer described above comprises a primer composition repelling the ink described above; when a cross section obtained by cutting the transparent pattern described above in a face orthogonal to the above transparent substrate is observed under a scanning electron microscope, the transparent pattern described above comprises a multilayer structure comprising a fixed repeating cycle and having a curved part and reflect selectively one of a left circularly polarized light component and a right circularly polarized light component in an incident light.