Retinal Projection Display With Movable-Mirror Exit Pupil Shifting
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Solution Overview
Problem
Existing retinal projection image display devices face challenges with a narrow eye box due to the image being focused on the pupil, leading to image disappearance with slight gaze changes, and the need for larger eyepiece optical systems to adjust for varying eye positions.
Innovation Solution
A retinal projection image display device with a variable optical system using a movable mirror and light collimator to change the incident position of light on the optical scanner, allowing the exit pupil to be moved without enlarging the eyepiece optical system, combined with a sensor to adjust for individual eye positions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the image is focused on the pupil using a conventional retinal projection system, then the image can be projected onto the retina, but the eye box becomes narrow causing image disappearance with slight gaze changes
Solution Approach 1:
The patent introduces a variable optical system with a movable mirror that can dynamically adjust the incident position of light on the optical scanner. This dynamic adjustment allows the exit pupil to be shifted to different positions, enabling the system to adapt to varying eye positions and gaze directions, thereby enlarging the effective eye box without compromising image stability on the retina.
2Adaptability or versatility
If a larger eyepiece optical system is used to adjust for varying eye positions, then the eye box can be enlarged, but the device size increases
Solution Approach 1:
Instead of increasing the physical size of the eyepiece optical system in one dimension, the patent utilizes the dimensional freedom of the movable mirror to shift the exit pupil position in a different dimensional space. By changing the incident position of light on the optical scanner through mirror rotation, the system achieves eye box enlargement without proportionally increasing the overall device volume.
3Device complexity
If the exit pupil is fixed, then the optical system is simple, but the image disappears when eye position changes
Solution Approach 1:
The patent changes the parameter of the exit pupil position by introducing a movable mirror with variable tilt. By adjusting the mirror's orientation, the incident position of light on the optical scanner changes, which in turn shifts the exit pupil position. This parameter change enables the system to maintain image visibility stability across different eye positions while adding only minimal optical complexity.
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
Enlarges the eye box, ensuring consistent image visibility across gaze directions and eye positions, maintaining compact device size and enhancing user experience by preventing image loss during eye movement.
Implementation Method 1
a light collimator to convert the light emitted from the light source into collimated light which is directed to the optical scanner
Implementation Method 2
a movable mirror with a variable tilt to change a reflection angle of the light emitted from the light source to the optical scanner
Data Source
AI summary
A retina projection image display device includes a light source to emit light; an optical scanner to scan the light emitted from the light source, to form an image with the scanned light; an eyepiece optical system to guide an exit pupil of the light scanned by the optical scanner to an eyeball; and a variable optical system between the light source and the optical scanner. The variable optical system includes a light collimator to convert the light emitted from the light source into collimated light which is directed to the optical scanner; and a movable mirror with a variable tilt to change a reflection angle of the light emitted from the light source to the optical scanner to change an incident position of the light emitted from the light source onto the optical scanner to shift the exit pupil.