Reducing Focal Planes in Near-Eye Displays via Spatial Light Modulators
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Solution Overview
Problem
Head-mounted displays used in virtual and extended reality applications face issues with vergence-accommodation conflict, causing user fatigue due to fixed screen locations, and existing solutions like multiple focal planes or time-multiplexing either result in distortion or hardware limitations such as bulkiness and power consumption.
Innovation Solution
The method involves mapping multiple focal planes to a reduced number, typically two focal planes, using depth-blending techniques and storing pixel location data to adjust perceived distances through a spatial light modulator, allowing for greater depth acuity while minimizing the number of displayed focal planes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If multiple focal planes are used to reduce vergence-accommodation conflict, then user comfort is improved, but device complexity and bulkiness increase
Solution Approach 1:
The patent combines multiple focal planes into a single display panel by using spatial light modulators to dynamically control the focal distance of different pixel regions. This merging approach eliminates the need for multiple physical transparent displays while maintaining multiple focal planes, thus reducing device complexity and bulkiness while still addressing vergence-accommodation conflict.
Solution Approach 2:
The patent employs dynamic focal adjustment through spatial light modulators that can change the focal distance of pixels in real-time based on the displayed content. This dynamic capability allows a single display panel to function as multiple focal planes, resolving the contradiction between providing multiple focal distances and maintaining simple device structure.
2Measurement precision
If more transparent displays are stacked to provide more focal planes, then depth acuity is improved, but power consumption and device bulk increase
Solution Approach 1:
The patent merges the functions of multiple power-consuming transparent displays into a single energy-efficient display panel with spatial light modulators. This consolidation maintains the depth acuity provided by multiple focal planes while significantly reducing overall power consumption by eliminating redundant display components.
Solution Approach 2:
The patent replaces the mechanical stack of multiple physical displays with an optical system using spatial light modulators that can dynamically adjust focal planes. This substitution eliminates the need for multiple physical layers, reducing both device bulk and power consumption while preserving depth acuity through optical control.
3Device complexity
If time-multiplexing is used to display multiple focal planes, then hardware complexity is reduced, but image quality deteriorates due to flickering and brightness loss
Solution Approach 1:
The patent segments the display panel into multiple independently controllable pixel regions, each associated with a specific focal distance. This segmentation allows simultaneous display of multiple focal planes in different spatial regions, eliminating the temporal multiplexing that causes flickering and brightness loss while maintaining hardware simplicity.
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 preserves depth acuity provided by higher numbers of focal planes while reducing the number of focal planes needed, thereby addressing hardware limitations and user discomfort caused by vergence-accommodation conflict.
Implementation Method 1
shift the positions of pixels in an image to different axial locations based on phase functions for each pixel and/or set of pixels
Implementation Method 2
lenses may focus the images of the two mapped focal planes
Data Source
AI summary
Systems and methods for reducing a number of focal planes used to display a three-dimensional object are disclosed herein. In an embodiment, data defining a three-dimensional image according to a first plurality of focal planes are received. Pixel luminance values from the first plurality of focal planes are mapped to a second plurality of focal planes comprising fewer focal planes than the first plurality of focal planes. Data is stored identifying initial focal distances of the mapped pixel luminance values in the first plurality of focal planes. The second plurality of focal planes are then displayed on a near eye device which uses the data identifying initial focal distances of the mapped pixel luminance values to adjust a wavelength of light produced by the second plurality of images to cause the pixels to appear at their original focal distances.