Folded Display Optics for Compact Eye Tracking
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Solution Overview
Problem
Head-mounted display (HMD) devices face challenges in being both sleek and optically powerful due to bulky optical components, which increase weight and cause user fatigue, hindering continuous use.
Innovation Solution
An optical assembly with a folded optical path using reflective elements, such as infrared filters or prisms, integrated into the HMD device to reduce size and weight, allowing for accurate eye tracking and diopter adjustment while minimizing the awareness of wearing the device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If extensive optical components are used to provide quality content and eye tracking, then optical performance and functionality are improved, but device size and weight increase causing user fatigue
Solution Approach 1:
The patent combines the display optical path and eye tracking optical path into a shared optical system. The same lenses and optical components serve dual purposes: delivering display content to the user's eye and capturing reflections for eye tracking. This merging eliminates the need for separate optical components for each function, significantly reducing overall device weight and size while maintaining both display quality and eye tracking accuracy.
Solution Approach 2:
The optical components in the HMD are designed to perform multiple functions simultaneously. The display lens serves both as the primary optical element for content delivery and as the reflective surface for eye tracking. The infrared illumination system and camera share the same optical path, allowing a single optical assembly to handle both display and sensing functions, thereby reducing the total component count and device weight.
2Reliability
If extensive optical components are used to provide quality content and eye tracking, then optical performance and functionality are improved, but device size and bulk increase
Solution Approach 1:
The patent merges the display optical path and eye tracking optical path into a shared optical system. The same lenses and optical components serve dual purposes: delivering display content to the user's eye and capturing reflections for eye tracking. This merging eliminates the need for separate optical components for each function, significantly reducing overall device size and volume while maintaining both display quality and eye tracking accuracy.
Solution Approach 2:
The patent utilizes the infrared spectrum dimension to enable eye tracking functionality. By employing infrared illumination and infrared-sensitive cameras, the system adds a wavelength dimension to the optical path, allowing eye tracking to occur through the same physical optical components used for visible light display, thereby avoiding additional bulk in the device structure.
3Ease of operation
If the device weight is reduced for user comfort, then ease of use is improved, but optical component quality and functionality may be compromised
Solution Approach 1:
The patent combines the display optical path and eye tracking optical path into a shared optical system. The same lenses and optical components serve dual purposes: delivering display content to the user's eye and capturing reflections for eye tracking. This merging eliminates the need for separate optical components for each function, significantly reducing overall device weight and size while maintaining both display quality and eye tracking accuracy.
4Volume of moving object
If a sleek, low-profile design is implemented, then device size and weight are reduced, but integrating sufficient optical components for accurate eye tracking becomes difficult
Solution Approach 1:
The patent combines the display optical path and eye tracking optical path into a shared optical system. The same lenses and optical components serve dual purposes: delivering display content to the user's eye and capturing reflections for eye tracking. This merging eliminates the need for separate optical components for each function, significantly reducing overall device size and volume while maintaining both display quality and eye tracking accuracy.
Solution Approach 2:
The patent uses infrared reflections as an optical copy or proxy for visible light reflections. By illuminating the eye with infrared light and capturing the infrared reflections with an infrared-sensitive camera, the system obtains accurate eye tracking data through the same optical path used for display, without requiring separate visible light sensors or additional optical components that would increase device 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 reduces the size and weight of HMD devices, enhancing user immersion in virtual reality environments by providing a streamlined, low-profile design with accurate eye tracking and improved vision correction.
Implementation Method 1
a first filter stack disposed between the at least one lens and the image projecting device, the first filter stack including at least one beam splitting layer
Implementation Method 2
a second filter stack between the first filter stack and the image projecting device, the second filter stack including at least one reflective element that faces the at least one lens
Implementation Method 3
Compact eye tracking using folded display optics
Data Source
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AI summary
Optical assemblies for use in virtual and augmented reality environments are described. The optical assemblies may include lenses, filter stacks, cameras, and image projecting devices. For example, the optical assemblies may include at least one lens, a first filter stack between the at least one lens and an image projecting device, a second filter stack between the first filter stack and the image projecting device, and a camera configured to capture images of an infrared reflection of light through the at least one lens.