Liquid Crystal Variable-Focus AR Display for Depth Comfort
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Solution Overview
Problem
Existing augmented reality (AR) systems face challenges in providing a comfortable and natural presentation of virtual image elements amidst real-world imagery due to the complexity of the human visual system, often causing discomfort from mismatches between accommodative and vergence states.
Innovation Solution
The use of thin adaptive lens assemblies with switchable waveplate assemblies, including liquid crystal layers and electrode patterns, to dynamically adjust optical power and align liquid crystal molecules, combined with roll-to-roll manufacturing methods for efficient production, allows for variable focus and reduced thickness and weight in AR displays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional AR display systems use multiple waveguides and lenses to provide depth perception, then depth perception capability is improved, but device complexity and weight increase
Solution Approach 1:
The patent combines multiple optical functions (waveguide, lens, polarization control) into a single integrated adaptive lens assembly. The liquid crystal layer integrated between waveplates performs multiple functions simultaneously: controlling polarization states, adjusting optical power, and enabling variable focus, thereby eliminating the need for separate waveguides and lenses while maintaining depth perception capability
Solution Approach 2:
The adaptive lens assembly serves multiple functions: it acts as a waveguide for light propagation, a variable focus lens for depth adjustment, and a polarization controller for optical modulation. The liquid crystal layer can dynamically change its optical properties to perform different functions, making the system universally capable of handling various optical requirements in AR displays
2Measurement precision
If conventional AR display systems use multiple waveguides and lenses to provide depth perception, then depth perception capability is improved, but weight increases
Solution Approach 1:
The patent combines multiple optical functions (waveguide, lens, polarization control) into a single integrated adaptive lens assembly. The liquid crystal layer integrated between waveplates performs multiple functions simultaneously: controlling polarization states, adjusting optical power, and enabling variable focus, thereby eliminating the need for separate waveguides and lenses while maintaining depth perception capability
Solution Approach 2:
The patent employs thin film structures, particularly the liquid crystal layer and waveplate configurations, to achieve the desired optical functions with minimal thickness. The flexible nature of liquid crystal materials allows for thin-film implementation of adaptive optics, significantly reducing the overall weight of the AR display system compared to conventional bulky lens and waveguide assemblies
3Measurement precision
If adaptive lens assemblies with liquid crystal layers are used to adjust optical power, then depth perception and user comfort are improved, but manufacturing complexity increases
Solution Approach 1:
The patent utilizes the ability of liquid crystal materials to change their optical parameters (refractive index, birefringence) in response to applied voltage. By controlling the voltage applied to the liquid crystal layer, the optical power of the lens can be dynamically adjusted, enabling variable focus and improved depth perception. This parameter-based control simplifies the manufacturing process compared to creating physically adjustable mechanical lens systems
Solution Approach 2:
The patent replaces mechanical adjustment mechanisms (such as movable lens elements or adjustable curvature structures) with an electrical field-based liquid crystal system. The liquid crystal layer responds to electrical signals to change its optical properties, eliminating the need for complex mechanical adjustment mechanisms and simplifying the overall manufacturing process while maintaining the ability to dynamically adjust optical power for depth perception
4Productivity
If roll-to-roll manufacturing process is used for producing AR display components, then productivity and efficiency are improved, but manufacturing precision may worsen
Solution Approach 1:
The patent divides the manufacturing process into distinct sequential stages: substrate preparation, liquid crystal layer deposition, waveplate integration, and final assembly. The roll-to-roll process efficiently handles the deposition and initial processing stages, while precision-critical steps such as waveplate alignment and bonding are performed in controlled subsequent stages, thereby maintaining manufacturing precision while benefiting from high-volume production efficiency
Solution Approach 2:
The patent performs preliminary preparation of substrates and liquid crystal layers using roll-to-roll processing, ensuring uniform coating and initial alignment before the components are assembled into the final device. This preliminary action in a high-speed manufacturing environment prepares the components with sufficient precision, allowing the final assembly to focus on critical alignment tasks, thereby balancing productivity and manufacturing precision
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 enhances the realism and comfort of AR experiences by aligning accommodative and vergence cues, providing a more natural perception of depth and reducing the overall thickness and weight of the display systems.
Implementation Method 1
a liquid crystal layer disposed in the volume between the first quarter-wave plate and the second quarter-wave plate, wherein liquid crystal molecules of the liquid crystal layer have selectively switchable orientations
Implementation Method 2
an electrode pattern disposed in the volume between the first quarter-wave plate and the second quarter-wave plate, the electrode pattern comprising a conductive material configured to selectively establish an electric field to change the orientations of the liquid crystal molecules
Implementation Method 3
a waveguide configured to output light to display an image
Data Source
AI summary
A display device includes a waveguide assembly comprising a waveguide configured to outcouple light out of a major surface of the waveguide to form an image in the eyes of a user. An adaptive lens assembly comprises a switchable waveplate assembly. The switchable waveplate assembly includes quarter-wave plates on opposing sides of a switchable liquid crystal layer, and electrodes on the quarter-wave plates in the volume between the quarter-wave plates. The electrodes can selectively establish an electric field and may serve as an alignment structure for molecules of the liquid crystal layer. Portions of the adaptive lens assembly may be manufactured by roll-to-roll processing in which a substrate roll is unwound, and alignment layers and liquid crystal layers are formed on the substrate as it moves towards a second roller, to be wound on that second roller.