Stacked Liquid Crystal Cells for Lower Drive Voltage and Faster Switching

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Solution Overview

Problem

Existing liquid crystal devices require high voltages and slow switching speeds to achieve refractive index changes across thick layers, limiting their application in adaptive lenses and other devices that need rapid focal adjustments.

Innovation Solution

A method involving a stack of liquid crystal cells with coincident electrode patterns and interconnected electrical circuitry, using concentric conductors and variable resistance elements, allows for the generation of refractive index patterns with lower drive voltages and faster switching speeds by aligning and rotating electrode patterns within the cells.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Length of stationary object

If voltages are applied across thick layers of liquid crystal material to achieve refractive index change, then the refractive index pattern is generated, but the drive voltage becomes excessively high and switching speed becomes slow

Engineering Contradiction:

Improvethickness of liquid crystal layerVSAvoiddrive voltage

Core Design Contradiction:

Length of stationary objectVSUse of energy by moving object

Solution Approach 1:

The patent divides a single thick liquid crystal cell into multiple thinner liquid crystal cells stacked together. Each cell has its own electrode patterns that are coincident with corresponding electrode patterns in other cells. By applying voltages across multiple thinner layers instead of one thick layer, the refractive index pattern is achieved with lower drive voltage while maintaining the required optical effect.

Inventive Principle:

Principle #1Segmentation

2Length of stationary object

If voltages are applied across thick layers of liquid crystal material to achieve refractive index change, then the refractive index pattern is generated, but the switching speed becomes slow

Engineering Contradiction:

Improvethickness of liquid crystal layerVSAvoidswitching speed

Core Design Contradiction:

Length of stationary objectVSSpeed

Solution Approach 1:

The patent divides a single thick liquid crystal cell into multiple thinner liquid crystal cells stacked together. Each cell has its own electrode patterns that are coincident with corresponding electrode patterns in other cells. By applying voltages across multiple thinner layers instead of one thick layer, the refractive index pattern is achieved with faster switching speed while maintaining the required optical effect.

Inventive Principle:

Principle #1Segmentation

3Use of energy by moving object

If multiple liquid crystal cells are stacked together to reduce drive voltage and increase switching speed, then the device complexity increases, but the manufacturing precision requirements become more stringent

Engineering Contradiction:

Improvedrive voltageVSAvoidalignment of electrode patterns

Core Design Contradiction:

Use of energy by moving objectVSManufacturing precision

Solution Approach 1:

The patent combines multiple liquid crystal cells into a single stack where the electrode patterns of corresponding electrodes in different cells are coincident (aligned). This merging approach allows the system to benefit from lower drive voltage and faster switching while managing manufacturing complexity through standardized alignment procedures during assembly.

Inventive Principle:

Principle #5Merging (Combining)

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

This approach enables the creation of adaptive lenses that can achieve the same focusing action as thicker single-cell devices but with significantly lower drive voltages and faster switching speeds, suitable for applications like augmented and virtual reality headsets.

Implementation Method 1

The refractive index of liquid crystal material is sensitive to electric fields. Some practical applications (such as adaptive lenses capable for relatively small focal lengths) require a change in refractive index throughout a relatively large thickness (e.g. 30 microns) of liquid crystal material; and such a change has been achieved by applying voltages across thick layers of liquid crystal material.

Methodology Applied

Scientific EffectElectro-optic effect: Electro-Optic Effects

Data Source

PatentUS11347101B2Device comprising a stack of individual liquid crystal cells having electrical circuitry operable to generate a stack of refractive index patterns and method of producing the same

Publication Date: 2022.05.31 FLEXENABLE TECH LTD

AI summary

A technique, comprising: producing at least first and second individual liquid crystal cells, wherein the first and second individual liquid crystal cells each comprise liquid crystal material between a respective pair of support components, and electrical circuitry operable to generate a refractive index pattern in the liquid crystal material; the method comprising adhering together at least the first and second liquid crystal cells to form a stack of liquid crystal cells; wherein the electrical circuitry of the first and second liquid crystal cells is operable together to generate a stack of refractive index patterns in the liquid crystal material of the stack of liquid crystal cells.