Variable-Focus Lens Pair Control for Presbyopic Mixed Reality
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Solution Overview
Problem
Presbyopic users face challenges in using mixed-reality HMD devices as they cannot simultaneously view both virtual and real-world objects in sharp focus due to the fixed focal plane of these devices, leading to discomfort and fatigue from vergence-accommodation conflict.
Innovation Solution
A pair of variable-focus lenses, comprising a negative lens on the eye-side and a positive lens on the real-world-side of a see-through optical combiner, are used to adjust the focus of virtual and real-world objects independently, allowing presbyopes to view both clearly without additional eyewear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a fixed-focus lens is used in the HMD device, then the device structure is simple, but presbyopic users cannot simultaneously view virtual and real-world objects in sharp focus
Solution Approach 1:
The patent employs variable-focus lenses that can dynamically adjust their focal length in response to user needs. The lens system transitions from a fixed focus to a dynamic focus mechanism that can adapt to different viewing distances, enabling presbyopic users to clearly view both virtual and real-world objects at various depths without requiring additional eyewear or complex manual adjustment mechanisms.
Solution Approach 2:
The invention changes the optical parameter of the lens by using variable-focus technology that can alter the focal length. This parameter change allows the same lens system to accommodate different object distances, resolving the contradiction between simplicity and adaptability for presbyopic users who need focus adjustment across multiple depths.
2Ease of operation
If a fixed focal plane is used in the HMD device, then the optical system is simple, but vergence-accommodation conflict occurs causing discomfort and fatigue
Solution Approach 1:
The patent introduces dynamic focus adjustment capability that allows the optical system to adapt to different viewing distances in real-time. This dynamic adjustment resolves the vergence-accommodation conflict by enabling the lens to change its focal plane according to the user's viewing needs, thereby improving visual comfort and reducing fatigue while maintaining reasonable system complexity.
3Adaptability or versatility
If additional eyewear is provided for presbyopic users, then vision correction is achieved, but the device complexity and user convenience are reduced
Solution Approach 1:
The patent merges the vision correction function directly into the HMD device's optical system by integrating variable-focus lenses. This consolidation eliminates the need for separate eyewear, as the device itself provides the necessary focus adjustment for presbyopic users, thereby improving user convenience while maintaining vision correction capability.
Solution Approach 2:
The variable-focus lens system provides multiple functions: it enables focus adjustment for different distances, corrects presbyopia, and maintains compatibility with both virtual and real-world viewing. This multi-functionality eliminates the need for additional eyewear and simplifies the overall user experience.
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
Enables presbyopes to comfortably view both virtual and real-world objects at any distance with reduced visual discomfort by dynamically adjusting the focus using conjugate variable-focus lenses, replicating corrective prescriptions for both near and far vision.
Implementation Method 1
A conjugate pair of variable-focus lenses is used in a mixed-reality head-mounted display device to enable a presbyopic user to simultaneously view both virtual-world and real-world objects in sharp focus
Implementation Method 2
The conjugate pair of variable-focus lenses is operable in matched configurations to provide for setting rendered virtual images within a near field without perturbing views of real-world objects in a far field
Data Source
Figure 1
Figure 2
Figure 3A~3C
AI summary
Variable-focus lenses are arranged as a lens pair that work on opposite sides of a see-through optical combiner used in a mixed-reality head-mounted display (HMD) device. An eye-side variable-focus lens is configured as a negative lens over an eyebox of the combiner to enable virtual-world objects to be set at a close distance. The negative lens is compensated by its conjugate using a real-world-side variable-focus lens configured as a positive lens to provide an unperturbed see-through experience. For non-presbyopes, the powers of the lenses are perfectly offset. For presbyopes, the lens powers may be mismatched at times to provide simultaneous views of both virtual-world and real-world objects on the display in sharp focus. Responsively an eye tracker indicating that the user is engaged in close viewing, optical power is added to the real-world-side lens to push close real-world objects optically farther away and into sharp focus for the presbyopic user.