Retinal Light Scanning Optics for Wider Eyebox Projection
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Solution Overview
Problem
AR glasses using the retinal scanning method face a narrow eyebox issue due to the condensing point of laser light not matching the pupils' positions, especially when the user moves their eyes, leading to incomplete video visibility.
Innovation Solution
A light scanning device with a movable mirror and a condensing optical system, such as a half-silvered mirror or a concave surface, that directs and condenses laser light to the center of the eyeball, using a simple configuration to maintain clear video projection even with eye movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a condensing optical system is used to condense laser light to a specific point, then the video can be projected clearly to the retina, but the eyebox becomes narrow because the condensing point must match the pupil position
Solution Approach 1:
The patent employs a movable mirror that can dynamically adjust its orientation to redirect laser light to different locations on the retina. This dynamic adjustment capability allows the system to adapt to varying pupil positions while maintaining clear video projection, effectively expanding the eyebox without sacrificing projection clarity.
Solution Approach 2:
The patent introduces a spatial dimension solution by using a movable mirror to redirect light to multiple locations on the retina. Instead of fixing the condensing point at a single location, the system adds temporal and spatial flexibility by moving the mirror to direct light to different retinal positions corresponding to different pupil locations, thus expanding the effective eyebox.
2Manufacturing precision
If the condensing point is fixed to match a specific pupil position, then clear video can be seen at that position, but the user cannot see video when eyes move away from this position
Solution Approach 1:
The movable mirror dynamically adjusts its angle and position to track eye movements and redirect laser light to the corresponding retinal locations. This dynamic tracking mechanism ensures that video remains visible even when the user moves their eyes, maintaining ease of operation without sacrificing video visibility.
Solution Approach 2:
The system incorporates eye tracking to detect pupil position and eye movement, using this feedback information to adjust the movable mirror's orientation. This feedback loop ensures that the laser light is continuously directed to the correct retinal position corresponding to the user's current eye position, maintaining video visibility throughout eye movements.
3Adaptability or versatility
If existing methods are used to expand the eyebox, then the eyebox can be enlarged, but the configuration becomes complicated
Solution Approach 1:
The movable mirror serves multiple functions: it acts as both a beam splitter and a directional control element, and the same optical path handles both eye tracking feedback and video projection. This multi-functionality reduces the need for separate components, thereby expanding the eyebox while keeping the overall system configuration simple.
Solution Approach 2:
The patent merges the eye tracking function and video projection function into a single integrated optical path using the movable mirror. By combining these functions, the system avoids the complexity of separate tracking and projection systems, achieving eyebox expansion with a unified, simpler configuration.
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
Expands the eyebox, ensuring clear video visibility across a wider range of eye movements without the need for complex configurations, reducing user discomfort.
Implementation Method 1
a mirror device that includes a movable mirror swinging about at least one axis and directionally changes the laser light emitted from the light source by reflecting the laser light using the movable mirror
Implementation Method 2
the condensing optical system is a half-silvered mirror or a mirror having a concave surface and condenses at least a part of the laser light directionally changed by the mirror device to the center of the eyeball by reflecting at least the part of the laser light using the concave surface
Implementation Method 3
a condensing optical system that condenses the laser light directionally changed by the mirror device to a center of an eyeball
Data Source
AI summary
A light scanning device includes a light source that emits laser light, a mirror device that includes a movable mirror swinging about at least one axis and directionally changes the laser light emitted from the light source by reflecting the laser light using the movable mirror, and a condensing optical system that condenses the laser light directionally changed by the mirror device to a center of an eyeball.