Holographic Optical Elements for Variable Dioptric Power
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Solution Overview
Problem
Existing head-worn image display apparatuses struggle to provide a variable dioptric power that adapts to changing observation distances, leading to eye strain, and are often bulky and expensive due to the need for mechanical mechanisms or special optical elements.
Innovation Solution
A head-worn image display apparatus using holographic optical elements that switch between two wavelengths of light to adjust the virtual image distance from the eye, eliminating the need for mechanical drives or special optical elements, allowing instantaneous dioptric power adjustment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a mechanical drive mechanism is used to move optical elements to vary dioptric power, then the dioptric power can be adjusted, but the device becomes bulky and heavy
Solution Approach 1:
The patent replaces mechanical drive mechanisms with a liquid crystal lens that changes its focal length by varying the refractive index through applied voltage. This substitution eliminates motors, gears, and mechanical moving parts, thereby reducing the weight and complexity of the image display apparatus while maintaining the capability to vary dioptric power.
Solution Approach 2:
The patent changes the refractive index parameter of the liquid crystal lens by applying different voltages, which directly varies the dioptric power of the observation optical system. This parameter-based control method avoids mechanical movement and reduces the overall device weight.
2Adaptability or versatility
If a mechanical drive mechanism is used to move optical elements to vary dioptric power, then the dioptric power can be adjusted, but the device complexity increases
Solution Approach 1:
The patent replaces complex mechanical drive mechanisms with a simple voltage control system that adjusts the refractive index of the liquid crystal lens. This substitution eliminates motors, transmission components, and mechanical linkages, thereby significantly reducing device complexity while maintaining dioptric power variability.
Solution Approach 2:
The patent uses voltage as a control parameter to change the refractive index of the liquid crystal lens, which in turn varies the dioptric power. This simple electrical parameter control replaces complex mechanical adjustment mechanisms, reducing overall device complexity.
3Adaptability or versatility
If a variable-shape mirror is used to vary dioptric power, then the dioptric power can be adjusted, but additional control components are required
Solution Approach 1:
The patent uses a liquid crystal lens whose refractive index can be varied by applying voltage, directly changing the dioptric power of the observation optical system. This approach replaces variable-shape mirrors and their associated complex control systems with a simpler voltage-controlled optical element.
4Adaptability or versatility
If a liquid crystal lens is used to vary dioptric power, then the dioptric power can be adjusted, but the device becomes expensive
Solution Approach 1:
The patent uses a liquid crystal lens whose refractive index can be varied by applying voltage, directly changing the dioptric power of the observation optical system. This approach replaces variable-shape mirrors and their associated complex control systems with a simpler voltage-controlled optical element.
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 enables a compact, lightweight, and see-through image display that reduces eye strain by instantly adjusting dioptric power based on observation distance without mechanical complexity or expensive components.
Implementation Method 1
a first holographic optical element that directs the first light from the display to an eye of the user so that a virtual image of the image represented by the first light is presented at a first distance from the eye of the user
Data Source
AI summary
In an image display apparatus, two light sources emit illumination light having different wavelengths, with which a liquid crystal display device is illuminated. By modulating the illumination light, the liquid crystal display device produces a first and a second image light having different wavelengths. Two holographic optical elements respectively reflect the first and second image lights and direct them to the user's eye so that virtual images of the images represented by the first and second image lights are formed at different positions. As the light source from which to obtain the illumination light is switched between the two, the dioptric power with which to present an image is changed.