Dynamic Image Shifting for Head-Mounted Display Resolution
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Solution Overview
Problem
Electronic displays, particularly in head-mounted display systems, often suffer from insufficient pixel density and visual artifacts like the 'screen door effect' due to insufficient resolution and dark interstitial areas between pixels, which can lead to a suboptimal user experience.
Innovation Solution
A method and system that dynamically shifts image pixels by fractions of the pixel pitch or entire pixel shifts to form offset subframes, enhancing effective image resolution and compensating for defective pixels, using image-shifting electro-optic devices and polarization gratings to improve pixel density and reduce visual artifacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If pixel density is increased to improve resolution, then image quality improves, but device size and manufacturing complexity increase
Solution Approach 1:
The patent applies dynamic image shifting technology where the image is shifted by fractions of a pixel pitch (e.g., 1/2, 1/3, 1/4) in multiple directions across different time periods. This dynamic shifting creates multiple virtual images from a single physical pixel array, effectively increasing the perceived resolution without physically increasing the pixel density. The image shifting is achieved through electro-optic devices that can rapidly change the optical path, allowing the same physical pixels to occupy multiple virtual positions.
Solution Approach 2:
The patent introduces a temporal dimension to the display system by displaying different shifted images at different time periods. Instead of only spatial arrangement of pixels, the system uses time-multiplexed display of multiple shifted images. The human visual system integrates these temporally separated images into a single high-resolution perception, effectively adding a time dimension to resolve the resolution-complexity contradiction.
2Measurement precision
If pixel size is reduced to increase pixel density, then resolution improves, but light emission area decreases and screen door effect worsens
Solution Approach 1:
The patent uses dynamic image shifting to create multiple virtual images from the same physical pixels. By shifting the image by sub-pixel amounts (fractions of pixel pitch) in different directions and displaying these shifted images at different time periods, the system effectively increases the number of light-emitting positions without reducing the physical pixel size. This maintains adequate light emission area while achieving higher effective pixel density through temporal and spatial multiplexing.
3Length of stationary object
If magnification is increased to improve apparent pixel size, then visibility improves, but angular resolution exceeds human eye capability and screen door effect increases
Solution Approach 1:
The patent dynamically shifts the image by fractions of the pixel pitch (e.g., 1/2, 1/3, 1/4 of pixel pitch) in multiple directions and displays these shifted images at different time periods. This creates multiple virtual images that effectively increase the angular resolution without increasing the physical magnification. The human eye perceives these temporally separated shifted images as a single high-resolution image, achieving fine angular resolution while maintaining the original pixel physical dimensions and avoiding the screen door effect.
4Device complexity
If static image display is used, then device simplicity is maintained, but effective resolution is limited by physical pixel density
Solution Approach 1:
The patent introduces dynamic image shifting where the image is shifted by sub-pixel amounts (fractions of pixel pitch) in multiple directions and displayed at different time periods. This dynamic approach creates multiple virtual images from a single physical pixel array, effectively increasing the resolution by a factor of N (where N is the number of distinct shift positions). The added complexity is minimal, primarily requiring an image shifter and temporal multiplexing control, while achieving N-fold resolution enhancement.
Solution Approach 2:
The patent employs periodic action by cyclically displaying different shifted images at different time periods. The image is shifted to different positions (e.g., 0, 1/4, 2/4, 3/4 of pixel pitch) in a periodic sequence, with each shifted image displayed for a brief period. This periodic temporal multiplexing allows the human visual system to integrate multiple low-resolution shifted images into a single high-resolution perception, achieving resolution enhancement through rhythmic temporal variation.
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 approach effectively increases the perceived image resolution and reduces visual artifacts like the 'screen door effect' by creating a higher effective pixel density and compensating for defective pixels, leading to an improved user experience in display systems.
Implementation Method 1
shifting an image of at least a portion of the electronic display by one or more image shifts synchronously with displaying the sequence of subframes, so as to form a sequence of offset subframe images
Implementation Method 2
using image-shifting electro-optic devices and polarization gratings to improve pixel density and reduce visual artifacts
Data Source
AI summary
A display apparatus includes an electronic display having a pixel array configured to display a sequence of subframes, and an image shifting electro-optic device that is operable to shift at least a portion of an image of the display pixel array synchronously with displaying the sequence of subframes, so as to form a sequence of offset subframe images for providing an enhanced image resolution and pixel correction in a compound image. The image shifting electro-optic device may include a polarization switch in series with a polarization grating, for shifting image pixels between offset image positions in coordination with displaying consecutive subframes.