Rear-Mounted Projector AR Display Balancing Center of Gravity
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Solution Overview
Problem
Existing display devices using diffraction elements face issues with image resolution due to light wavelengths deviating from a specific wavelength, leading to decreased mounting stability when the image light projecting device is positioned forward, causing the center of gravity to be forward and resulting in tilting of the frame when mounted on a head.
Innovation Solution
A display device configuration where the image light projecting device is positioned rearward, with a first reflective diffraction element emitting light towards a second diffraction element, allowing for wavelength compensation and improved mounting stability by balancing the center of gravity rearward, using a first and second light-guiding system to direct image light efficiently and correct aberrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the image light projecting device is disposed frontward to achieve a compact structure, then the device complexity is reduced, but the mounting stability deteriorates due to forward center of gravity causing frame tilting
Solution Approach 1:
The patent inverts the conventional arrangement by positioning the image light projecting device rearward instead of frontward. This inversion resolves the contradiction by placing the heavy component at the rear to balance the center of gravity, preventing frame tilting while maintaining structural compactness through the folded optical path.
2Device complexity
If a single diffraction element is used to simplify the optical system, then the device complexity is reduced, but the image resolution deteriorates due to wavelength deviation effects
Solution Approach 1:
The patent segments the diffraction function into two separate diffraction elements with distinct roles. The first diffraction element diffracts image light in a first direction, and the second diffraction element diffracts it in a second direction. This segmentation enables wavelength compensation between the two elements, maintaining high image resolution while managing optical system complexity through modular functional division.
3Stability of the object's composition
If the image light projecting device is positioned rearward to improve mounting stability, then the center of gravity is balanced rearward, but the optical path length increases requiring additional light-guiding components
Solution Approach 1:
The patent merges the light-guiding function with the diffraction elements by integrating reflective surfaces and light-guiding structures into the same optical components. The first light-guiding system and second light-guiding system are combined with the diffraction elements, reducing the need for separate guiding components and managing optical path complexity while maintaining mounting stability.
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 configuration enhances image resolution by compensating for wavelength deviations and improves mounting stability by positioning the image light projecting device rearward, reducing the likelihood of frame tilting during use.
Implementation Method 1
a first light-guiding system including a first reflective element disposed on a first side in a first direction with respect to the image light projecting device, the first light-guiding system being configured to emit the image light projected from the image light projecting device toward a second side in the first direction by the first reflective element
Implementation Method 2
a first diffraction element having a reflectivity, and configured to emit the image light emitted from the first reflective element toward the first side in the first direction
Implementation Method 3
a second diffraction element having a reflectivity, and configured to emit the image light emitted from the first diffraction element toward the second side in the first direction
Data Source
AI summary
In an optical system of a display device, an image light projecting device emits image light toward a first side in a first direction. A reflective element of a first light-guiding system emits the image light emitted from the image light projecting device toward a second side in the first direction. A first diffraction element having a reflectivity emits the image light emitted from the reflective element toward the first side in the first direction. A second diffraction element having a reflectivity emits the image light emitted from the first diffraction element toward the second side in the first direction and causes the image light to be incident on an eye of an observer. An optical path from the first diffraction element to the second diffraction element is provided in a second light-guiding system.