Multi-Depth Liquid Crystal Lens 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 at the periphery, which is exacerbated by increasing the thickness of the liquid crystal layer, resulting in slower switching speeds.
Innovation Solution
The solution involves a multi-depth liquid crystal lens design with varying thickness layers and stepped electrode widths, using concentric regions with increasing thickness and electrode widths, and employing resistive bridges and buss lines to maintain effective electric field strength across the lens diameter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the liquid crystal layer thickness is increased to maintain electric field strength in larger diameter lenses, then the electric field strength is improved, but the switching speed deteriorates
Solution Approach 1:
The liquid crystal layer is segmented into multiple depth layers (first depth layer and second depth layer) with different thicknesses. The first depth layer has a greater thickness to generate a stronger electric field for outer ring electrodes, while the second depth layer has a lesser thickness for inner ring electrodes, maintaining overall switching speed performance.
Solution Approach 2:
Different regions of the liquid crystal layer are assigned different thicknesses based on their functional requirements. The outer regions (first depth layer) have greater thickness to compensate for the weaker electric field generation capability of outer ring electrodes, while the inner regions (second depth layer) have lesser thickness to maintain fast switching response.
2Area of stationary object
If the lens diameter is increased to improve optical coverage, then the area is improved, but the electrode width to gap width ratio deteriorates
Solution Approach 1:
The solution moves from a two-dimensional planar electrode structure to a three-dimensional multi-depth structure. By adding the depth dimension with multiple liquid crystal layers, the patent can maintain adequate electrode widths in the radial direction while increasing the overall lens diameter, as the electric field strength is enhanced through vertical layering rather than requiring larger radial electrode dimensions.
Solution Approach 2:
The electrode system is segmented into multiple independent ring electrodes at different depths. This segmentation allows each electrode to be optimized independently for its specific radial position, maintaining appropriate width-to-gap ratios for each while collectively covering a larger lens diameter.
3Measurement precision
If the number of ring electrodes is increased to improve optical control, then the precision is improved, but the device complexity deteriorates
Solution Approach 1:
By utilizing the depth dimension with multiple liquid crystal layers, the patent can achieve fine optical control through vertical stratification. This reduces the need for a large number of radially-distributed electrodes, as precision is achieved through the combination of depth-layer control and fewer radial zones, thereby reducing overall structural complexity.
Solution Approach 2:
The multiple liquid crystal layers are nested concentrically within each other, with each layer containing a set of ring electrodes. This nested structure allows for sophisticated optical control through the superposition of fields from multiple layers, achieving high precision with a compact and organized electrode architecture rather than requiring numerous independent electrodes.
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 faster switching speeds and improved electrode-to-gap ratios, maintaining optical effectiveness and reducing degradation, suitable for applications such as ophthalmic lenses and augmented 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.
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.