Prism Virtual Image Display with Asymmetric Curved Surfaces
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Solution Overview
Problem
Existing virtual image display apparatuses for head mount displays suffer from limited wide-angle views, weightiness, and inability to simultaneously view image light and external light without distortion, due to inadequate optical systems that obstruct external light reception and cause blurring.
Innovation Solution
A compact and lightweight virtual image display apparatus with a prism-type image forming optical system using non-axisymmetric curved surfaces to form intermediate images, allowing simultaneous viewing of image light and external light by passing external light through specific surfaces, reducing diopter scale and distortion, and optimizing the optical system's design to fit closely to the observer's face.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a relay optical system with asymmetric curved surfaces is used to make the optical system compact, then the device size and weight are reduced, but the external light reception is insufficient and distortion occurs
Solution Approach 1:
The patent applies asymmetry by using non-axisymmetric curved surfaces in the relay optical system. Specifically, the optical system includes surfaces with different curvatures in different directions (meridional and sagittal surfaces), which allows compact design while correcting eccentric aberrations and maintaining proper external light reception. This asymmetric design enables the optical system to be compact without sacrificing image quality.
Solution Approach 2:
The patent implements local quality by giving different optical properties to different parts of the optical system. The relay optical system has specific curved surfaces with predetermined curvatures designed to handle image light differently from external light. This localized optimization allows the system to maintain compact size while ensuring proper function for both image light transmission and external light reception in specific regions.
2Device complexity
If the image display device is placed in the upper part of the eyes, then the optical system can be designed, but the wearing sensation is poor and the form is less desirable
Solution Approach 1:
The patent applies dimensionality change by moving the image display device from the traditional upper position to the lateral position alongside the face. This spatial reconfiguration in another dimension allows the optical system to maintain its design complexity while dramatically improving wearing sensation and aesthetic appearance by positioning the device in a more ergonomically favorable location.
3Adaptability or versatility
If the observer's view is totally covered by the image light, then the virtual reality experience is enhanced, but the observer cannot judge the status of the external world
Solution Approach 1:
The patent implements universality by designing the optical system to perform multiple functions simultaneously. The relay optical system with non-axisymmetric curved surfaces is configured to guide both image light from the display device and external light from the environment to the observer's eyes. This multi-functional design allows the observer to experience virtual reality while simultaneously maintaining awareness of the external world through see-through capability.
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 enables a high-performance, wide-angle display with reduced weight and improved wearing sensation, allowing clear, undistorted viewing of both image light and external light, enhancing the user experience by minimizing optical aberrations and maintaining a sleek design.
Implementation Method 1
After the image light from the image element is totally reflected on the third surface, then totally reflected on the first surface and then is reflected on the second surface
Implementation Method 2
When the external world is viewed by passing through a first surface and a third surface among a plurality of surfaces constituting the prism type image forming optical system, a diopter scale is approximately zero
Data Source
AI summary
An intermediate image is formed inside a first prism, and an image light, which is reflected on the order of a third surface, a first surface and a second surface, is transmitted through the first surface and reaches the eyes of the observer, therefore it is possible to make the entire optical system small and light in weight by making the first prism thin, and realize a high performance display device with a wide angle of view. Further, when an external light is passed through, for example, the first surface and the third surface and observed, a diopter scale is set to approximately zero, and thereby reducing the defocus or distortion of the external light when observed in a see-through manner. And, it is possible such that the shape of the first prism conforms to the face of the observer, the center is also close to the face.