Spatially Separated Exit Pupils in Head Mounted Displays
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Solution Overview
Problem
Conventional head-worn and heads-up displays face challenges in achieving a large field of view without bulkiness, as the optical system's eyebox limits the placement and movement of the wearer's eye, restricting the field of view to approximately 20 degrees.
Innovation Solution
The implementation of a multiple exit pupil system using a holographic optical element that directs light from multiple spatially separated entrance pupils to create multiple exit pupils, allowing for an enlarged viewing area by projecting a virtual image at these exit pupils proximate to the user's eye, thereby increasing the field of view and accommodating anthropometric differences and eye rotation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional optical systems are used to provide a virtual image, then the field of view is limited by the optical system eyebox, but the system remains compact
Solution Approach 1:
The patent divides the single exit pupil into multiple spatially separated exit pupils (first exit pupil and second exit pupil). Each exit pupil corresponds to a different wavelength range and is formed by dedicated optical paths with mirrors and beam splitters. This segmentation allows the system to accommodate multiple eye positions and rotations, effectively enlarging the field of view without requiring a single complex optical system
Solution Approach 2:
The patent introduces beam splitters as intermediary components to separate and direct different wavelength ranges to different exit pupils. The first beam splitter separates the first wavelength range from the second wavelength range, while the second beam splitter further directs light to appropriate mirrors. These intermediaries enable the complex wavelength-based optical routing without requiring a single monolithic optical system
2Adaptability or versatility
If the eyebox is enlarged to accommodate eye movement and rotation, then the field of view increases, but the optical system becomes bulky
Solution Approach 1:
The patent creates different exit pupils optimized for specific wavelength ranges and eye positions. The first exit pupil is optimized for the first wavelength range and specific eye positions, while the second exit pupil is optimized for the second wavelength range and different eye positions. This local optimization allows each pupil to handle specific viewing conditions efficiently, accommodating eye rotation without requiring a uniformly enlarged optical system that would increase overall volume
Solution Approach 2:
The patent introduces wavelength as an additional dimension for organizing optical paths. By separating light into different wavelength ranges and routing them through different optical paths to different exit pupils, the system effectively uses the wavelength dimension to manage the complexity of accommodating multiple eye positions and rotations. This wavelength-based dimensionality allows the system to handle eye movement tolerance without proportionally increasing the physical volume of the optical system
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 solution provides an enlarged field of view and tolerance for eye rotation, allowing users to perceive a projected virtual image without the need for bulky optics, while maintaining a normal eyewear form factor.
Implementation Method 1
a holographic optical element to receive the light from the plurality of entrance pupils and reflect at least a portion of the light to a plurality of exit pupils
Data Source
AI summary
Disclosed herein are devices and methods to provide multiple eyeboxes from multiple input pupils. In particular, a projection system can direct light from multiple input pupils to a holographic optical element. The light of each of the input pupils having light beams of different wavelengths. The holographic optical element reflects at least part of the light of the multiple input pupils to form an array of exit pupils.