Folded-Path Optical Lens Assembly for Head-Mounted Zoom
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Solution Overview
Problem
Current head-mounted displays are heavy, have poor image quality, and require users with myopia or hyperopia to wear additional glasses, affecting comfort and performance.
Innovation Solution
An optical lens assembly with a specific configuration of lens groups and optical elements that includes a first lens group with positive refractive power, a second lens group with positive or negative refractive power, and optical elements like absorptive and reflective polarizers, phase retarders, and a partial-reflective-partial-transmissive element, arranged to fold the light path and provide a zoom function without additional glasses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the light path is folded to reduce device size, then the weight and size are reduced, but the image quality may deteriorate
Solution Approach 1:
The optical system is divided into multiple lens groups (first lens group with positive refractive power, second lens group with positive or negative refractive power) that can be independently configured. This segmentation allows each group to perform specific optical functions while collectively achieving compact folding without compromising image quality
Solution Approach 2:
The patent employs a folded light path design where the optical axis is bent at angles (e.g., 45 degrees) using reflective elements. This transforms a linear optical path into a multi-dimensional configuration, reducing the overall device volume while maintaining effective optical path length for high-quality imaging
2Device complexity
If a fixed-focus design is used to simplify the device, then the device complexity is reduced, but users with myopia or hyperopia cannot use it comfortably
Solution Approach 1:
The patent implements a movable second lens group that can be displaced along the optical axis to adjust the focal length of the optical system. This dynamic adjustment mechanism enables the device to accommodate different vision requirements (myopia, hyperopia, normal vision) while maintaining a relatively simple overall structure
Solution Approach 2:
The focal length of the optical system is made variable by changing the position of the second lens group. By adjusting the distance between lens groups, the system can adapt to different user vision needs without requiring complex prescription-specific designs for each user
3Adaptability or versatility
If zoom function is added to enhance functionality, then the adaptability is improved, but the device complexity increases
Solution Approach 1:
The second lens group is designed to be movable relative to the first lens group, enabling dynamic adjustment of the optical system's focal length. This single degree of freedom movement provides zoom functionality while avoiding the need for multiple fixed-focus optical systems
Solution Approach 2:
The movable second lens group serves multiple functions: it adjusts focus for different vision prescriptions and simultaneously provides zoom capability by changing the effective focal length. This multi-functionality reduces the need for separate mechanisms for each function
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 reduces the weight and size of the device, improves image quality, and allows users to use it without additional glasses, while enhancing the field of view and zoom capabilities.
Implementation Method 1
a first lens group with positive refractive power... a second lens group with positive or negative refractive power
Implementation Method 2
an absorptive polarizer, a reflective polarizer
Implementation Method 3
a first phase retarder... a second phase retarder
Implementation Method 4
a partial-reflective-partial-transmissive element
Data Source
AI summary
An optical lens assembly includes: a first element group including: a first lens group with positive refractive power, including one or two lenses; a second element group including: a second lens group with positive refractive power, including two or three lenses; an optical element including, in order from a visual side to an image source side: an absorptive polarizer, a reflective polarizer and a first phase retarder; and a partial-reflective-partial-transmissive element; and a third element group including an image source plane. The first element group, the second element group and the third element group are arranged in order from the visual side to the image source side. When the optical lens assembly satisfies a specific condition, the weight of the device can be reduced, the zoom function can be provided, and the image quality can be ensured.