Stepped Liquid Crystal Lens Structure for Large-Diameter Switching
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Solution Overview
Problem
Existing liquid crystal lenses face limitations in diameter due to the decreasing ratio of electrode width to gap width, leading to reduced electric field strength and optical effectiveness, particularly at the lens periphery, which affects switching speed and overall performance.
Innovation Solution
The implementation of a stepped or tiered substrate surface with varying liquid crystal thickness and electrode widths, where the electrodes are arranged in concentric regions with increasing thickness and width, allowing for multiple voltage applications to maintain effective electric fields across the lens diameter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the lens diameter is increased while maintaining uniform electrode and gap widths, then the lens can cover a larger area, but the electrode width to gap width ratio decreases leading to reduced electric field strength and optical effectiveness
Solution Approach 1:
The patent applies local quality by varying the electrode widths and liquid crystal thickness according to radial position. Outer regions have wider electrodes and greater thickness to compensate for the reduced electrode-to-gap ratio, while inner regions maintain original dimensions. This localized adaptation ensures uniform electric field strength and optical effectiveness across the entire lens area.
2Reliability
If the liquid crystal thickness is increased to maintain electric field strength, then the optical effectiveness is improved, but the switching speed decreases
Solution Approach 1:
The patent implements local quality by creating radially varying liquid crystal thickness. The center region maintains thinner liquid crystal for fast switching, while outer regions have increased thickness to compensate for the reduced electrode-to-gap ratio and maintain adequate electric field strength. This localized thickness variation resolves the contradiction between electric field strength and switching speed.
3Reliability
If the electrode widths are increased uniformly across the lens, then the electric field strength is improved, but the manufacturing complexity and material usage increase
Solution Approach 1:
The patent applies parameter changes by varying the electrode width parameter as a function of radial position. Instead of uniform electrodes, the width parameter changes continuously or in steps from the center to the periphery. This controlled parameter variation maintains electric field strength while avoiding the excessive complexity of other approaches.
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 design enables larger diameter liquid crystal lenses with maintained switching speed and improved electrode-to-gap width ratios, enhancing optical performance and flexibility in applications such as ophthalmic lenses and augmented/virtual reality systems.
Implementation Method 1
Applying a voltage to the patterned electrodes creates an electric field across the liquid crystal. The liquid crystal molecules, which are anisotropic, align themselves with the electric field, changing the local refractive index.
Implementation Method 2
Applying a voltage gradient to the patterned electrodes creates a gradient electric field, with each electrode producing a different electric field than its neighbor. Because the electric field influences the index of refraction of the liquid crystal, the gradient electric field results in a gradient of change in index of refraction in the liquid crystal, which can in turn produce an optical lensing effect.
Data Source
AI summary
A typical liquid crystal lens includes liquid crystal sandwiched between transparent substrates, which are patterned with ring electrodes. Applying a voltage across the electrodes causes the liquid crystal molecules to rotate, changing their apparent refractive index and the lens's focal length. The ring electrodes are separated by gaps and get narrower toward the lens's periphery. If the ring electrodes are too narrower, their cannot switch the liquid crystal well. To address this problem, an inventive liquid crystal lens includes a substrate with a stepped surface that defines concentric liquid crystal regions with thicknesses that increase with lens radius. Each region is switched by a different set of ring electrodes, which may be on, under, or opposite the stepped surface. Within each region, the ring electrodes get narrower farther from the lens's center. But the ring electrodes' widths also increase with liquid crystal thickness, offsetting the decrease in width that degrades lens performance.