Waveguided Display With Antiparallel Liquid Crystal Lenses
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Solution Overview
Problem
Electronic devices with displays face challenges in achieving desired optical performance and aesthetics, particularly in head-mounted devices for augmented and virtual reality, where components can appear unsightly and bulky, and there is a need to maintain linear polarization of light to prevent image artifacts.
Innovation Solution
The use of liquid crystal lenses with antiparallel pretilt angles and rubbing directions, mounted on both surfaces of a waveguide, along with control circuitry to adjust their refractive indices, allows for the modulation of image light while canceling out optical power applied to external world light, ensuring minimal modulation of real-world light and maintaining linear polarization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If liquid crystal lenses are mounted on waveguide surfaces to modulate image light, then optical performance is improved, but device complexity increases
Solution Approach 1:
The patent combines multiple liquid crystal lenses (first and second lenses with antiparallel pretilt angles) into a single integrated optical system mounted on the waveguide. This merging approach allows the system to achieve complex optical modulation functions while maintaining a compact form factor, resolving the contradiction between improved optical performance and increased device complexity.
Solution Approach 2:
The patent utilizes variable pretilt angles in the liquid crystal lenses that can be dynamically adjusted through electrical control. By changing the pretilt angle parameters, the system can modulate the optical power applied to image light versus world light, enabling precise control over the optical performance without requiring additional mechanical components.
2Reliability
If optical power is applied to image light through liquid crystal lenses, then display quality is improved, but external world light is also modulated causing image artifacts
Solution Approach 1:
The patent employs a second liquid crystal lens with antiparallel pretilt angles that generates equal and opposite optical power to counterbalance the modulation effect on world light. This anti-weight approach ensures that while image light receives the necessary optical power for high display quality, the world light passing through the system experiences net zero modulation, preventing image artifacts.
Solution Approach 2:
The patent creates different optical effects for different light paths by utilizing the antiparallel pretilt configuration. The first liquid crystal lens applies optical power selectively to image light for enhanced display quality, while the second lens compensates specifically for world light, achieving local quality optimization for each light type without affecting the other.
3Reliability
If linear polarization is maintained to prevent image artifacts, then image quality is improved, but device complexity increases due to additional polarization control components
Solution Approach 1:
The patent utilizes the inherent polarization-maintaining properties of the liquid crystal lens configuration itself to preserve linear polarization. The antiparallel pretilt angles and aligned rubbing directions of the liquid crystal lenses naturally maintain the linear polarization state of both image and world light without requiring additional polarizing filters or beam splitters, thus improving image quality while avoiding increased device complexity.
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 configuration enhances the optical performance by adjusting the optical characteristics of image light without affecting external light, reducing image artifacts and maintaining polarization, thus improving the display quality in head-mounted devices.
Implementation Method 1
Control circuitry may control the first liquid crystal lens to exhibit a first index-of-refraction profile that applies a first optical power to the image light and the world light. The control circuitry may control the second liquid crystal lens to exhibit a second index-of-refraction profile that applies a second optical power to the world light that at least partially cancels out the first optical power.
Implementation Method 2
The image light may propagate through the waveguide under the principle of total internal reflection.
Implementation Method 3
A linear polarizer may be interposed between the waveguide and the first liquid crystal lens to ensure the linear polarization aligns with the rubbing directions of the liquid crystal lenses.
Data Source
AI summary
An electronic device may have a display that provides image light to a waveguide. First and second liquid crystal lenses may be mounted to opposing surfaces of the waveguide. An coupler may couple the image light out of the waveguide through the first lens. The second lens may convey world light to the first lens. Control circuitry may control the first lens to apply a first optical power to the image light and the world light and may control the second lens to apply a second optical power to the world light that cancels out the first optical power. Each lens may include two layers of liquid crystal molecules having antiparallel pretilt angles. The pretilt angles and rubbing directions of the first lens may be antiparallel to corresponding pretilt angles and rubbing directions of the second lens about the waveguide.