VR Display Tilt and Fresnel Coating to Reduce Stray Light
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Solution Overview
Problem
Virtual reality display apparatuses have insufficient vertical view angles, leading to black borders and reduced viewing quality due to non-optical effective areas in Fresnel lenses causing stray light, and are not adjustable for different users' vision needs.
Innovation Solution
The display and optical assembly are tilted relative to the upward direction by an angle between 0 and 20 degrees, and the non-optical effective areas of Fresnel lenses are coated with a light-absorbing material to expand the vertical field of view and reduce stray light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the upper and lower fields of view are designed with the same range, then the device structure is simplified, but a black border appears in the lower part of the field of view
Solution Approach 1:
The patent applies asymmetry by designing the lower field of view range to be greater than the upper field of view range, matching the asymmetric viewing characteristics of human eyes. This resolves the contradiction by accepting asymmetric design to eliminate the black border issue while maintaining structural simplicity through optimized parameter configuration.
Solution Approach 2:
The patent changes the field of view parameters to have different ranges for upper and lower directions, specifically setting the lower field of view angle greater than the upper field of view angle. This parameter adjustment eliminates the black border problem while keeping the overall device structure simple and manageable.
2Weight of moving object
If a Fresnel lens is used in the optical assembly, then the weight and volume of the optical assembly are reduced, but stray light occurs due to the non-optical effective area
Solution Approach 1:
The patent converts the harmful non-optical effective area of the Fresnel lens into a beneficial light-blocking structure by coating it with light-absorbing material. This transforms the stray light problem into an opportunity to improve optical performance while maintaining the weight and volume advantages of the Fresnel lens design.
Solution Approach 2:
The patent applies local quality by selectively coating only the non-optical effective area of the Fresnel lens with light-absorbing material, while leaving the optical effective area unchanged. This localized treatment eliminates stray light without compromising the optical performance or adding excessive weight.
3Device complexity
If the distance between optical assemblies is fixed and focal length is non-adjustable, then the device structure is simplified, but it cannot be suitable for all people with different vision needs
Solution Approach 1:
The patent introduces adjustability mechanisms that allow users to modify the distance between optical assemblies and adjust focal length according to their vision needs. This dynamic configuration enables the device to adapt to different users while maintaining a relatively simple base structure through modular design.
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 enhances the user's vertical field of view and improves viewing quality by blocking stray light, making the virtual reality display more suitable for various users, including those with vision corrections.
Implementation Method 1
the non-optical effective area of the Fresnel lens is coated with a light absorbing material. With the non-optical effective area of the Fresnel lens which is coated with the light absorbing material, the light can be blocked from passing through the optical assembly from the non-optical effective area
Data Source
AI summary
A virtual reality display apparatus including at least a display and at least an optical assembly is provided. The display provides an image beam to a user's left eye or right eye. The optical assembly disposed on the transmission path of the image beam includes at least a Fresnel lens. Each of the display and the optical assembly both has a tilt angle relative to an upward direction, wherein the upward direction is the direction perpendicular to the user's horizontal sight line plane and defined as the direction pointing from the user's neck to the top of the user's head, and the tilt angle is within a range greater than 0 degree and is smaller than or equal to 20 degrees.