Variable-Power Lenses for Stereoscopic Display Accommodation
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Solution Overview
Problem
Stereoscopic display devices cause unnatural viewing experiences due to eye accommodation issues, leading to blurriness and discomfort as the eyes attempt to focus at the apparent 3D distance rather than the actual display distance, resulting in defocused images.
Innovation Solution
A stereoscopic display device with variable-power lenses and a gaze distance tracker that adjusts the power of the lenses based on the tracked gaze distance to ensure the images are focused on the retinas, using the formula Dacc(t) = 1/TDD - 1/AOD(t) to maintain clear vision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the left and right images are placed close to the respective eyes in a head-mounted display to provide a compact design, then the device compactness is improved, but the eye accommodation becomes problematic because the human eye cannot focus too close, requiring additional accommodation lenses
Solution Approach 1:
An optical system including a display screen and accommodation lenses is introduced as an intermediary between the user's eyes and the displayed images. The accommodation lenses specifically mediate the focusing function, allowing the display to be positioned close to the eyes while maintaining proper focus at a desired virtual distance.
Solution Approach 2:
The optical system creates a virtual copy of the display images at a different perceived distance from the user's eyes. By using accommodation lenses, the system projects a virtual image that appears to be at a comfortable viewing distance rather than at the physical display location, enabling compact head-mounted design without compromising eye comfort.
2Ease of operation
If the eyes are positioned at a distance from the display screen to avoid accommodation issues, then the eye accommodation comfort is improved, but the device becomes less compact and more difficult to wear
Solution Approach 1:
The accommodation lenses serve as an optical intermediary that decouples the physical distance between eyes and display from the perceived viewing distance. This allows the display to be positioned close to the eyes for compactness while the lenses create the optical effect of viewing from a more comfortable distance.
Solution Approach 2:
The mechanical constraint of physical display distance is replaced by an optical solution using accommodation lenses. Instead of requiring the user's eyes to be at a specific mechanical distance from the display, the system uses optical elements to achieve the same accommodation effect, enabling compact head-mounted design.
3Ease of operation
If the eyes focus at the apparent distance of the 3D object, then the natural focusing function is maintained, but the actually viewed left and right images become defocused causing blurriness and visual distortion
Solution Approach 1:
The accommodation lenses act as an optical intermediary that bridges the discrepancy between the apparent 3D object distance and the actual display distance. When the user focuses on the virtual 3D image at its apparent distance, the accommodation lenses ensure that the light from the display screen is properly focused on the retina, eliminating blurriness and visual distortion.
Solution Approach 2:
The optical system provides feedback by continuously adjusting the optical path through the accommodation lenses based on the user's focusing state. The system ensures that when the user's eyes accommodate to the virtual image distance, the optical elements compensate to deliver a sharp focused image on the retina, creating a closed-loop visual system.
4Device complexity
If the stereoscopic display device uses a larger single screen viewed by both eyes with polarization-based eye selection, then the device complexity is reduced by eliminating accommodation lenses, but the viewing distance increases and may not be suitable for head-mounted applications
Solution Approach 1:
The optical system creates a virtual copy of the display images at a perceived distance that is different from the physical display location. By using accommodation lenses, the system projects virtual images that appear to be at a comfortable viewing distance, enabling the use of compact display screens in head-mounted devices without requiring large viewing distances.
Solution Approach 2:
The system separates the physical dimension (actual display-screen distance) from the perceived dimension (virtual image distance). By manipulating the optical path through accommodation lenses, the system allows the display to be physically close to the user's eyes while creating the perception of viewing from a more distant virtual location, effectively adding an optical dimension to the viewing geometry.
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 solution provides a natural 3D viewing experience by accurately focusing the images on the retinas, reducing eyestrain and discomfort by aligning the eye accommodation with the gaze distance, thereby maintaining image clarity.
Implementation Method 1
variable-power lenses including a left variable-power lens arranged to provide eye accommodation for the left eye and a right variable-power lens arranged to provide eye accommodation for the right eye
Implementation Method 2
the power of the variable power lenses to focus the left and right images on the retinas of the respective left and right eyes
Data Source
AI summary
A stereoscopic display device is provided for displaying a three-dimensional (3D) image as viewed by eyes consisting of a left eye and a right eye. In the display device, a single display screen, or separate left and right display screens, present a left image to the left eye but not the right eye, and present a right image to the right eye but not the left eye. A gaze distance tracker is configured to track gaze distance of the eyes. Variable-power lenses include a left variable-power lens arranged to provide eye accommodation for the left eye, and a right variable-power lens arranged to provide eye accommodation for the right eye. An electronic eye accommodation controller is configured to control the power of the variable power lenses to allow the image from the display to be focused on the retina, while the biological eye lens is accommodated to the gaze distance.