Switchable Lenses for Bright Object Visibility in AR Displays
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Solution Overview
Problem
Head-mounted devices with optical combiners struggle to maintain visibility of computer-generated images in bright ambient lighting conditions, as real-world light can overpower the lower-intensity image light, causing washout or obscuration of virtual content.
Innovation Solution
The implementation of adjustable illumination optics within the display module, which can switch between uniform and non-uniform intensity states, focusing more light on specific regions of the spatial light modulator to enhance the visibility of bright objects even in high ambient light environments, using switchable lenses and diffractive gratings controlled by sensor data and circuitry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the illumination intensity is increased to maintain visibility of computer-generated images in bright ambient lighting conditions, then the visibility of virtual content is improved, but the power consumption increases
Solution Approach 1:
The illumination optics system provides different illumination intensities to different regions of the display panel. Bright objects in the virtual image receive enhanced illumination to maintain visibility in bright ambient conditions, while other regions receive normal or reduced illumination. This selective local enhancement maintains image visibility without requiring uniform increase in power consumption across the entire display.
Solution Approach 2:
The illumination optics includes adjustable components that can dynamically change the illumination pattern based on ambient lighting conditions and the specific content being displayed. The system adapts in real-time, switching between uniform and non-uniform illumination modes, and adjusting focal lengths or optical powers to concentrate light only where needed, thereby optimizing power consumption while maintaining visibility.
2Illumination intensity
If the illumination optics are made adjustable to focus light on specific regions, then the visibility of bright objects is improved, but the device complexity increases
Solution Approach 1:
The illumination optics system utilizes adjustable optical components such as switchable lenses or diffractive gratings that can change their optical parameters (focal length, optical power, diffraction pattern) to focus illumination on specific regions of the display panel. These parameter changes enable dynamic control of light distribution without requiring complex mechanical reconfiguration of the entire optical system.
Solution Approach 2:
The system replaces complex mechanical adjustment mechanisms with electronically controlled optical elements. Switchable lenses and diffractive gratings are controlled by circuitry that receives sensor data and image data, enabling automated adjustment of illumination patterns without manual intervention or complex mechanical linkages, thereby reducing overall device complexity while maintaining functionality.
3Illumination intensity
If the illumination is focused on a subset of the display panel area, then the intensity within that subset is increased, but the uniformity of illumination across the panel is reduced
Solution Approach 1:
The illumination optics system can switch between different illumination modes (uniform and non-uniform) based on the requirements of the displayed content and ambient conditions. When bright objects need emphasis, the system periodically applies focused illumination to specific regions, then returns to uniform illumination when not needed, creating a dynamic balance between local intensity enhancement and overall uniformity.
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 ensures that bright objects in the image remain visible and perceivable by the user, even in bright ambient light conditions, without increasing power consumption or the size of the device, by dynamically adjusting the illumination to counteract the intensity of surrounding light.
Implementation Method 1
The adjustable optical components may include switchable lenses having adjustable optical powers and/or focal lengths
Implementation Method 2
The optical system may include a waveguide that forms an optical combiner to combine the image light with real world light
Implementation Method 3
The optical system may include a waveguide that forms an optical combiner to combine the image light with real world light
Implementation Method 4
The display panel may produce the image light by modulating the illumination light with corresponding images
Data Source
AI summary
An electronic device may have an optical combiner, a spatial light modulator, and illumination optics. The modulator may produce image light for the combiner by modulating illumination light from the illumination optics. Adjustable optical components in the illumination optics may be controlled to adjust the illumination optics between first and second states. In the first state, the adjustable optical components may provide the illumination light to the modulator with a uniform intensity across the lateral area of the modulator. In the second state, the adjustable optical components may focus the illumination light within a subset of the lateral area. The subset of the lateral area may correspond with a bright object in the image light. The control circuitry may control the illumination optics to ensure that the bright object remains visible at an eye box even when the device is located in bright ambient lighting conditions.