HMD Optical System Lens Arrangement for Wide Angle View
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Solution Overview
Problem
Conventional head-mounted displays (HMDs) face challenges in miniaturization and weight reduction due to the limitations of their optical systems, which restrict portability and comfort, and struggle to provide a large image with high resolution and a wide angle of view without increasing the system size and weight.
Innovation Solution
An optical system for HMDs is designed with first and second lenses arranged along the optical axis, where the first lens has positive refractive power and the second lens has negative refractive power, with specific curvature and focal length ratios, and aspheric surfaces, to gradually increase the angles of principal rays, enhancing the angle of view and image resolution while reducing the overall system size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional optical systems with half mirrors and reflective mirrors are used, then enlarged images can be provided to users, but the system size and weight increase, reducing portability and comfort
Solution Approach 1:
The patent extracts and eliminates the half mirror and reflective mirror components from the conventional optical system. By removing these heavy components, the system achieves significant weight reduction while maintaining the core function of providing enlarged images to users through a simplified lens-based optical path
Solution Approach 2:
The patent replaces the mechanical reflective mirror system with an optical lens system. The multiple lenses (including positive and negative power lenses) substitute for the half mirror and reflective mirror arrangement, achieving image enlargement through refraction rather than reflection, thereby reducing system weight and complexity
2Adaptability or versatility
If conventional optical systems are used, then images can be displayed, but the angle of view is limited and the sense of presence is reduced
Solution Approach 1:
The patent divides the optical system into multiple specialized lens components (including positive power lenses, negative power lenses, and field lenses) arranged in sequence. This segmentation allows each lens to optimize specific optical functions, collectively achieving a wide angle of view of 70 degrees or more while maintaining high image quality and sense of presence
Solution Approach 2:
The patent expands the optical system in the longitudinal dimension by arranging multiple lenses along the optical axis. This dimensional expansion enables the system to achieve a wide angle of view and large field of view without increasing lateral size, thereby improving sense of presence while controlling overall system dimensions
3Weight of moving object
If the optical system is miniaturized for portability, then weight is reduced, but the ability to provide large high-resolution images is compromised
Solution Approach 1:
The patent assigns different optical properties to different lens components along the optical path. Positive power lenses provide convergence and image formation, negative power lenses provide divergence control, and field lenses optimize field curvature. This local optimization of lens qualities enables high-resolution imaging in a compact configuration
Solution Approach 2:
The patent utilizes lenses with specific focal length ratios and curvature relationships (|R1/R2|>2.5 and |f1/f2|<0.6) to optimize the optical system. By carefully selecting and adjusting these optical parameters, the system achieves high image resolution while maintaining a compact, lightweight form factor suitable for portability
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 design achieves a compact and lightweight HMD with an increased angle of view of 70° or more, enabling a high-resolution, large-screen image with improved sense of presence and involvement, while maintaining a reduced system size and weight.
Implementation Method 1
first and second lenses are sequentially disposed along an optical axis so as to allow angles of principal rays incident upon an image plane to be gradually increased... The first lens has positive refractive power, and the second lens has negative refractive power
Data Source
AI summary
An optical system for a head-mounted display in which image rays provided from a display device are divergent to form and provide an enlarged image is configured so that first and second lenses are sequentially disposed from an object along an optical axis and provide the enlarged image on an image plane, and angles of principal rays are gradually increased from the optical axis toward the edge of the image plane. Thus, as the angles of principal rays are increased, an angle of view is improved to provide a large screen so that it is possible to appreciate a vivid image due to an increase in the sense of presence and the degree of involvement. The entire size of the optical system can be reduced. The head-mounted display can be made compact and lightweight.