Head-Mounted Display Image Rotation and Replication Unit
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Solution Overview
Problem
Existing head-mounted displays (HMDs) face challenges in achieving both miniaturization and high efficiency of their optical systems while expanding the eye box to accommodate images with long horizontal aspects, leading to increased size and decreased optical efficiency.
Innovation Solution
The HMD incorporates an image rotation and replication unit with an incidence surface, an emission surface, and at least two reflection surfaces, where the angle between the incidence surface and the emission surface is greater than 90°, allowing for the expansion of the eye box while maintaining a compact design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If the eye box is expanded by a pupil replication unit and a waveguide unit, then the visual field coverage is improved, but the optical system size increases and optical efficiency decreases
Solution Approach 1:
The patent introduces an image rotation and replication unit that operates in a rotated coordinate system relative to the waveguide unit. By rotating the image light by a predetermined angle (e.g., 45 degrees) before replication, the system expands the eye box in a different dimensional orientation, allowing compact packaging while maintaining expanded visual field coverage.
Solution Approach 2:
The optical system is divided into functionally independent units: a waveguide unit for light transmission, an image rotation and replication unit for eye box expansion, and a pupil replication unit for further optimization. This segmentation allows each unit to be optimized independently and packaged compactly, resolving the contradiction between eye box expansion and system size.
2Adaptability or versatility
If the width of virtual image generation unit is increased to correspond to horizontal aspect ratio, then the image display capability is improved, but the HMD design is deteriorated
Solution Approach 1:
The image rotation and replication unit rotates the image light by a predetermined angle, effectively transposing the aspect ratio orientation. This allows the system to display horizontal aspect ratio images through a compact vertical form factor, maintaining HMD design aesthetics while preserving full image display capability.
Solution Approach 2:
The patent employs asymmetric angle configurations in the image rotation and replication unit (e.g., 45-degree rotations) to transform the aspect ratio characteristics of the displayed image. This asymmetric geometric transformation enables flexible adaptation to different display requirements without compromising the compact HMD form factor.
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 configuration enables the HMD to achieve both miniaturization and high efficiency of the optical system while expanding the eye box, improving image visibility and reducing manufacturing costs.
Implementation Method 1
an image rotation and replication unit configured to expand an eye box of projection light from the projection unit... The image rotation and replication unit includes an incidence surface, an emission surface, and at least two reflection surfaces
Data Source
AI summary
A head-mounted display achieves both miniaturization and high efficiency of an optical system and expansion of an eye box. In order to achieve the above-described object, a head-mounted display that displays an image within a visual field of a user is provided. The head-mounted display includes: an image display unit that generates an image to be displayed; a projection unit that projects image light from the image display unit; an image rotation and replication unit that expands an eye box of projection light from the projection unit; and a waveguide unit that transmits image light from the image rotation and replication unit to a pupil of the user. The image rotation and replication unit includes an incidence surface, an emission surface, and at least two reflection surfaces, and an angle formed by the incidence surface and the emission surface is greater than 90°.