Tunable LC Microlenses for Variable Focal Depth Waveguide Displays
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional see-through waveguide displays in augmented reality devices often present virtual images at a fixed focal depth, leading to focus mismatch with real-world objects, causing image blur and user discomfort due to the inability to adjust focal depths for virtual images.
Innovation Solution
A near-eye optical display system incorporating a see-through waveguide and a curved two-sided array of electrically-activated tunable liquid crystal (LC) microlenses, which allows for individual wavefront shaping and selective implementation of multiple focal depths for virtual images, while maintaining the focus of real-world images by activating only the necessary LC microlenses based on the user's gaze direction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If virtual images are displayed at a fixed focal depth in a see-through waveguide display, then the device structure is simple, but the user experiences focus mismatch with real-world objects causing image blur and discomfort
Solution Approach 1:
The patent implements dynamically adjustable focal depths for virtual images using tunable liquid crystal microlenses. The system can switch between different focal planes (e.g., infinity focus and near focus) based on user needs, making the display adaptive rather than static. This resolves the contradiction by enabling multiple focal depths without permanently complicating the base device structure.
Solution Approach 2:
The patent changes the optical parameters of the display system by introducing tunable microlenses that can alter their focal length dynamically. By adjusting the lens power of individual microlenses in the array, the system can present virtual images at different focal depths while maintaining a relatively simple waveguide structure, thus improving user comfort without proportionally increasing device complexity.
2Adaptability or versatility
If multiple LC microlenses are simultaneously activated to provide multiple focal depths, then virtual images can appear at various distances, but edge effects including boundary diffraction and optical aberrations reduce image quality
Solution Approach 1:
The patent employs temporal multiplexing where adjacent pixels are scanned sequentially rather than simultaneously. The LC microlenses are switched on and off in a scanning pattern (e.g., raster scanning or every second/third/fourth pixel), creating a time-separated activation sequence. This periodic action prevents simultaneous activation of overlapping microlenses, thereby eliminating boundary diffraction effects while still providing multiple focal depths through temporal integration.
Solution Approach 2:
The system pre-calculates and pre-arranges the scanning sequence of pixels and corresponding microlens activation patterns to avoid simultaneous activation of adjacent microlenses. By planning the activation时序 in advance, the system prevents edge effects before they occur, maintaining image quality while achieving focal depth versatility.
3Adaptability or versatility
If LC microlenses are activated at waveguide display locations to shape wavefronts, then multiple focal depths are achieved, but the complexity of controlling individual microlenses increases
Solution Approach 1:
The patent divides the control of the microlens array into manageable segments by mapping specific regions of the waveguide display to specific groups of LC microlenses. Only the microlenses corresponding to the currently displayed virtual image region are activated, while others remain inactive. This segmentation reduces the number of simultaneously controlled microlenses and simplifies the control architecture.
Solution Approach 2:
The system applies different control strategies to different regions of the microlens array. Each microlens or group of microlenses is controlled independently based on local requirements for wavefront shaping. This localized control approach reduces overall system complexity by only activating and controlling the necessary portion of the array at any given time, rather than managing the entire array uniformly.
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 enhances the quality and immersion of the augmented reality experience by allowing virtual images to appear in focus at various distances without affecting the real-world image focus, reducing eye strain and cognitive dissonance.
Implementation Method 1
A curved two-sided array of electrically-activated tunable liquid crystal (LC) microlenses... Each pixel in the waveguide display is mapped to an LC microlens in the array... The LC microlenses may be electrically activated to thereby individually shape the wavefront of each pixel in a virtual image
Implementation Method 2
a see-through waveguide display having optical elements configured for in-coupling virtual images from an imager, exit pupil expansion, and out-coupling virtual images with expanded pupil to the user's eye
Data Source
AI summary
A near-eye optical display system utilized in augmented reality devices includes a see-through waveguide display having optical elements configured for in-coupling virtual images from an imager, exit pupil expansion, and out-coupling virtual images with expanded pupil to the user's eye. The near-eye optical display system further includes a curved two-sided array of electrically-activated tunable liquid crystal (LC) microlenses that is located between the waveguide and the user's eye. The LC microlenses are distributed in layers on each side of the two-sided array. Each pixel in the waveguide display is mapped to an LC microlens in the array, and multiple nearby pixels may be mapped to the same LC microlens. A region of the waveguide display that the user is gazing upon is detected and the LC microlens that is mapped to that region may be electrically activated to thereby individually shape the wavefront of each pixel in a virtual image.