Waveguide HMD Light Shielding for Stray Light and Ghosting
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Solution Overview
Problem
Existing head-mounted display (HMD) devices face issues with stray light and ghosting, which degrade visual quality and user experience in augmented reality applications.
Innovation Solution
Incorporating a light shielding element between the projection device and the waveguide element to block redundant and diverged image beams, thereby reducing unexpected light and light spots, which improves optical display quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a light shielding element is added to block stray light, then visual quality is improved, but device complexity increases
Solution Approach 1:
A light shielding element is introduced as an intermediary component between the projection device and waveguide element. This element selectively blocks stray light and ghost images while allowing the main image beam to pass through, thereby improving visual quality without fundamentally changing the core optical architecture.
Solution Approach 2:
The light shielding element is designed with a segmented structure featuring a light shielding portion and a light transmitting portion. This segmentation allows selective blocking of harmful light paths while maintaining transparency for useful light, achieving harm reduction without excessive complexity.
2Object-affected harmful factors
If the light shielding element blocks all stray light, then display quality improves, but light transmission efficiency decreases
Solution Approach 1:
The light shielding element exhibits spatially varying properties: the light shielding portion has high blocking capability for stray light, while the light transmitting portion maintains high transparency for the main image beam. This local differentiation ensures effective stray light reduction without compromising overall light transmission efficiency.
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
Effectively reduces stray light and ghosting, enhancing the optical display quality and user experience by minimizing noise in virtual images.
Implementation Method 1
the image beam is transmitted by the at least one waveguide element
Implementation Method 2
the light shielding element is disposed between the projection device and the light incident end of the at least one waveguide element, where the image beam has a stop, and the stop is located at external of the projection device
Data Source
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AI summary
A HMD device includes a projection device, at least one waveguide element and a light shielding element. The projection device is configured to provide an image beam. The at least one waveguide element has a light incident end and a light output end, where the light incident end is configured to receive the image beam, and the image beam is transmitted by the at least one waveguide element and emitted from the light output end. The light shielding element is disposed between the projection device and the light incident end of the at least one waveguide element, where the image beam has a stop, and the stop is located at external of the projection device. The HMD device of the invention effectively reduces generation of unexpected light or light spot, so as to avoid displaying noise or ghost in a display image.