Virtual Image-Forming Lens Design for Wider HMD Visibility
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Solution Overview
Problem
Existing head-mounted displays (HMDs) struggle to provide a highly immersive experience by allowing users to clearly view images from both front and lateral views due to reduced image resolution when viewing from lateral positions.
Innovation Solution
Incorporating virtual image forming optical systems with positive power regions and power adjusting regions set closer to the negative side at the outer sides of the optical axes, and using a combination of lenses to adjust focal positions for improved image clarity from various angles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If spherical design lenses or aspherical lenses with constant power are used for virtual image forming optical systems, then the optical system is simple and easy to manufacture, but the image resolution decreases when viewing from lateral positions due to increased gap between screen and focal position
Solution Approach 1:
The patent applies local quality by varying the power distribution across different regions of the lens. Specifically, the lens has a first power region at the optical center and a second power region at peripheral portions with different power values. This non-uniform power distribution allows the lens to maintain appropriate focal positions for both front view (optical center) and lateral view (peripheral portions), thereby resolving the contradiction between manufacturing simplicity and image resolution across different viewing angles.
2Device complexity
If constant power lenses are used, then the device complexity is low, but the range of clear visibility is limited to front view only
Solution Approach 1:
The lens is designed with spatially varying power distribution, having a first power region at the optical center and a second power region at peripheral portions. This local differentiation enables the single lens to accommodate multiple viewing angles (front and lateral views) without requiring complex multi-lens systems or adjustable mechanisms, thus expanding the range of clear visibility while maintaining relatively low device complexity.
3Device complexity
If the focal position is fixed for front view, then the optical system is simple, but images at peripheral portions cannot be clearly viewed from lateral positions
Solution Approach 1:
Instead of using a single fixed focal position, the patent implements multiple focal positions through spatially varying power regions in the lens. The first power region at the optical center provides focus for front view, while the second power region at peripheral portions provides focus for lateral view. This allows the optical system to maintain image clarity across different viewing angles without requiring complex mechanical adjustment mechanisms.
Solution Approach 2:
The lens design effectively creates a dynamic focal structure where different regions of the lens provide different focal positions. This dynamic focal distribution allows the optical system to adapt to different viewing angles automatically, providing clear images both at front view and lateral positions without requiring active adjustment mechanisms.
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 users to clearly view images from both front and lateral views, expanding the range of clear visibility and maintaining high image resolution.
Implementation Method 1
virtual image forming optical systems with predetermined power set positive for obtaining virtual images (magnified upright images) of images for the left eye and the right eye displayed on a display device
Data Source
AI summary
Provided is a head-mounted display capable of expanding the range in which a user can clearly view images. A head-mounted display 1 includes a display device 3 to display images 3a and 3b for the left eye and the right eye on a screen 3c, and virtual image forming optical systems 4a and 4b for the left eye and the right eye respectively disposed with respect to the images 3a and 3b for the left eye and the right eye on the screen 3c, wherein the virtual image forming optical systems 4a and 4b have positive power set in respective regions that visual lines of a user pass through, and include, at outer sides of optical centers in directions orthogonal to optical axes, power adjusting regions 55 having power set closer to the negative side than power at the optical centers.