Optical System Pupil Reconstruction for Brighter, Thinner AR Glasses
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Solution Overview
Problem
Existing optical systems in augmented reality glasses suffer from low light utilization efficiency and difficulty in achieving brightness suitable for outdoor use due to inefficient light guidance and pupil reconstruction, leading to challenges in reducing battery weight and maintaining image quality at wide angles of view.
Innovation Solution
The optical system employs a light guide plate with a projection unit and a pupil reconstruction mirror that forms a second pupil at the eyepoint outside the light guide, using a configuration that satisfies specific inequalities to maintain light beam convergence and angle of view, incorporating reflective surfaces and retroreflectors to enhance light guidance and reduce thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If conventional light guide plates are used in augmented reality glasses, then the device can provide virtual image display, but the light utilization efficiency is low and brightness is insufficient for outdoor use
Solution Approach 1:
The patent introduces a light guide plate as an intermediary component between the display element and the observer's eye. This light guide plate captures light from the display element and guides it to the eye, significantly improving light utilization efficiency. The light guide plate acts as a mediator that enables effective light transmission while maintaining compact device dimensions.
Solution Approach 2:
The patent modifies optical parameters including the focal length of the projection unit, the position and size of pupils, and the geometry of reflective surfaces. By optimizing these parameters, the system achieves high light utilization efficiency and sufficient brightness for outdoor use while maintaining a compact form factor.
2Loss of energy
If the optical system is designed to guide light efficiently to the eyepoint, then light utilization efficiency improves, but the device thickness increases
Solution Approach 1:
The patent employs reflective surfaces and light guide plates that operate in multiple dimensions to guide light efficiently. By utilizing angular reflection and three-dimensional light path management, the system achieves high light utilization efficiency without increasing the linear thickness of the device. The light guide plate thickness is optimized to balance light guidance effectiveness with device compactness.
3Device complexity
If the projection unit forms a pupil inside the light guide, then light guidance is simplified, but the angle of view and image quality at wide angles deteriorate
Solution Approach 1:
The patent divides the pupil formation process into segments: a first pupil is formed by the projection unit, and a second pupil is formed by reflective surfaces within the light guide plate. This segmentation allows independent optimization of each pupil's position and size, enabling wide angle of view and improved image quality while maintaining relatively simple light guidance structure.
Solution Approach 2:
The patent creates a second pupil that is a geometric copy or transformation of the first pupil. By forming a second pupil at a different position and size within the light guide plate, the system preserves the optical characteristics while enabling wider angle of view and improved image quality at peripheral fields.
4Loss of energy
If retroreflectors are added to the light guide plate, then light guidance efficiency improves, but manufacturing complexity increases
Solution Approach 1:
The patent merges the light guide plate and retroreflector into a single integrated component. The retroreflector is formed as part of the light guide plate structure, combining light guidance and light return functions in one element. This integration improves light guidance efficiency while simplifying manufacturing compared to separate components.
Solution Approach 2:
The light guide plate serves multiple functions simultaneously: it guides light from the display element, acts as a structural support, and incorporates retroreflective surfaces to return light. This multi-functionality reduces the need for separate components, simplifying manufacturing while maintaining high light guidance 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
The system achieves high light utilization efficiency and reduced thickness, enabling brighter images suitable for outdoor use while minimizing battery weight by effectively guiding light to the observer's eye with improved pupil reconstruction.
Implementation Method 1
a projection unit configured to project the light from the display element
Implementation Method 2
a light guide configured to guide the light from the projection unit to the eyepoint... The light guide has a reflector configured to form a second pupil at the eyepoint
Implementation Method 3
a light guide configured to guide the light from the projection unit to the eyepoint... satisfying specific inequalities to maintain light beam convergence
Data Source
AI summary
An optical system configured to guide light from a display element to an eyepoint includes a projection unit configured to project the light from the display element, and a light guide configured to guide the light from the projection unit to the eyepoint. The eyepoint is located outside the light guide. The projection unit forms a first pupil. The light guide has a reflector configured to form a second pupil at the eyepoint in a first section parallel to a first direction. A predetermined inequality is satisfied.