Bifocal Optical Assembly with Liquid Crystal Lens for Near-Eye Displays
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Solution Overview
Problem
Near-eye displays for VR, AR, and MR applications suffer from the vergence-accommodation conflict, causing eye strain and degraded visual experience due to mismatched focusing and convergence states, especially affecting users of different ages with varying accommodation abilities.
Innovation Solution
A bifocal optical assembly with a liquid crystal (LC) lens having adjustable optical power, driven by eye-tracking information to dynamically adjust the image distance and mitigate the vergence-accommodation conflict by providing separate focal planes for different image distances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a fixed focal length optical system is used, then the device structure is simple, but it causes vergence-accommodation conflict and eye strain for users of different ages
Solution Approach 1:
The patent implements a liquid crystal lens whose focal length can be dynamically adjusted based on eye-tracking information. The optical assembly transitions from a fixed focal length system to a dynamic one, allowing real-time adaptation to user accommodation needs while managing complexity through integrated control mechanisms
Solution Approach 2:
The patent changes the optical parameter (focal length) of the lens system to accommodate different user ages and visual conditions. By adjusting the focal length parameter dynamically, the system adapts to varying accommodation abilities without requiring completely different optical designs for each user group
2Adaptability or versatility
If a single focal plane is provided, then the optical system is simple, but it cannot accommodate both near and far vision requirements
Solution Approach 1:
The patent segments the optical assembly into distinct portions: a first optical element portion for focusing at a first image plane and a second optical element portion containing the liquid crystal lens for focusing at a second image plane. This segmentation enables multi-focal functionality while maintaining manageable complexity through modular design
Solution Approach 2:
The optical assembly is designed to perform multiple functions through a unified structure. The liquid crystal lens can dynamically switch between different focal lengths, allowing the same optical system to serve both near and far vision requirements, eliminating the need for separate optical systems for different viewing distances
3Ease of operation
If the image distance is fixed, then the optical system is stable and simple, but it causes eye strain due to mismatched focusing and convergence states
Solution Approach 1:
The patent incorporates eye-tracking information to control the liquid crystal lens. The system continuously monitors user eye position and accommodation state, then adjusts the focal length accordingly. This feedback mechanism ensures the optical system adapts to user needs in real-time, improving visual comfort while managing complexity through automated control
Solution Approach 2:
The optical system performs self-adjustment based on detected eye-tracking information. The liquid crystal lens automatically modifies its focal length to match the user's accommodation state without requiring manual intervention. This self-service capability improves ease of operation while the integrated control system manages the complexity of dynamic adjustment
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 effectively reduces eye strain and improves the visual experience by accommodating different user age groups by dynamically adjusting the focal length to match the vergence distance, enhancing the usability and comfort of near-eye displays.
Implementation Method 1
a liquid crystal ("LC") lens having an adjustable optical power
Implementation Method 2
configured to focus a second portion of the image light propagating through the second optical element portion
Data Source
AI summary
A device includes a light source configured to emit an image light. The device also includes an optical assembly configured to direct the image light to an eye-box of the device. The optical assembly includes a first optical element portion configured to focus a first portion of the image light propagating through the first optical element portion. The optical assembly also includes a second optical element portion configured to focus a second portion of the image light propagating through the second optical element portion. The second optical element portion includes a liquid crystal (“LC”) lens having an adjustable optical power.