Optical Waveguide Shadow Mask for Virtual Image Stray Light Suppression
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional head-up displays suffer from reduced image quality and contrast due to stray light, particularly solar radiation, which causes spectral dispersion and heating issues within the optical fiber, leading to weakened images.
Innovation Solution
A device with an optical waveguide equipped with a shadow mask having holes and non-transparent areas, along with a reflective layer or air gap, is used to prevent stray light from entering and exiting the optical fiber, ensuring total reflections and precise light bundling for improved image quality. Additionally, multiple optical waveguides with shadow masks allow for multicolor displays and reduced stray light coupling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If sunlight enters the optical waveguide, then the waveguide can guide light, but spectral dispersion and heating occur causing image quality degradation
Solution Approach 1:
A shadow mask is introduced as an intermediary element positioned between the optical waveguide and the external environment. The shadow mask selectively blocks stray light and parasitic light paths while allowing the useful light from the display element to pass through to the viewer's eye. This mediator resolves the contradiction by filtering harmful light without interfering with the intended light transmission.
Solution Approach 2:
The optical system is segmented into distinct functional zones: the optical waveguide for light guidance, the shadow mask for light filtering, and the display element for image generation. By segmenting the system, the shadow mask can specifically address stray light interference without affecting the core light guidance function of the waveguide, thus improving image quality while maintaining light transmission.
2Area of stationary object
If the optical waveguide is made larger to widen the exit pupil, then the eyebox size increases, but the device becomes more complex and larger
Solution Approach 1:
The shadow mask is nested within or positioned in close proximity to the optical waveguide structure, integrating the light filtering function directly into the existing optical path. This nesting approach allows the system to achieve stray light suppression without requiring separate, additional optical components that would increase device complexity and size.
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 significantly enhances image quality and contrast by minimizing stray light interference, reducing heating, and allowing for precise light extraction, resulting in a clearer and more stable virtual image display.
Implementation Method 1
The light coupled into the optical fiber undergoes total internal reflection at its interfaces and is thus guided within the fiber
Implementation Method 2
A shadow mask arranged above an upper boundary surface of the optical waveguide, which has holes and opaque areas
Implementation Method 3
a first light-incident-side diffraction grating that diffracts incident light to cause the diffracted light to enter the optical waveguide
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
The invention relates to an apparatus for generating a virtual image with interference light suppression. The apparatus comprises at least one light source for generating light source for generating light having a predetermined wave length, a display element for generating an image and an optical waveguide (5) for expanding an exit pupil. A shadow mask (91) is arranged above an upper boundary surface (501) of the optical waveguide (5) and comprises perforations (92, 92R, 92G, 92B) and non-transparent regions (93, 93R, 93G, 93B).