Varifocal Assembly for VR Headset Field of View and Resolution
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Solution Overview
Problem
Virtual reality headsets face challenges in maintaining optimal field of view (FOV) and resolution during transitions between high and low FOV applications, leading to undesirable artifacts and inefficient energy consumption.
Innovation Solution
A varifocal assembly in the headset adjusts the angular size of the display pixels, allowing for reconfigurable optical settings that spread or condense pixels to achieve high resolution and brightness in focused or immersive modes, respectively, using optical elements like diffractive and refractive components, and polarizing filters to manage light beams based on desired modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the field of view is reduced to focus on detailed aspects of a scene, then the resolution and brightness are lost, but the image quality deteriorates with artifacts
Solution Approach 1:
The patent applies a varifocal optical element that dynamically adjusts the field of view and focal length based on user interaction. When users zoom in to focus on detailed aspects, the optical element concentrates light beams to maintain high resolution and brightness without artifacts. When users zoom out for immersive viewing, the optical element expands the field of view accordingly. This dynamic adaptation resolves the contradiction by making the optical system flexible rather than fixed.
Solution Approach 2:
The patent changes optical parameters including focal length, field of view, and light beam distribution through the varifocal element. By adjusting these parameters in response to user input, the system can switch between focused mode (high resolution, narrow FOV) and immersive mode (low resolution, wide FOV), preventing resolution loss and brightness dimming when zooming in while avoiding excessive brightness when zooming out.
2Area of stationary object
If the field of view is increased for immersive viewing, then the resolution is maintained, but the brightness becomes overly high and energy consumption increases
Solution Approach 1:
The varifocal optical element dynamically adjusts light beam distribution based on the desired field of view. In immersive mode with wide field of view, the optical element spreads light beams across a larger area, naturally reducing brightness intensity and energy consumption per degree of view. This dynamic control prevents excessive brightness while maintaining immersive experience.
Solution Approach 2:
The system changes optical parameters to match the operational mode. When field of view is increased for immersive viewing, the varifocal element adjusts the light beam convergence to distribute illumination more broadly, reducing peak brightness and overall energy consumption. This parameter adjustment ensures efficient energy usage across different viewing scenarios.
3Measurement precision
If the pixel density is increased to maintain resolution during FOV transitions, then the resolution is preserved, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
The varifocal optical element acts as an intermediary between the display and the user's eye. Instead of increasing pixel density on the display to maintain resolution during FOV transitions, the optical element mediates the light beams to concentrate or spread them as needed. This approach preserves resolution without requiring higher pixel density hardware.
Solution Approach 2:
The patent replaces the mechanical approach of increasing physical pixel density with an optical solution using a varifocal element. Rather than changing the hardware resolution, the system uses optical beam manipulation to achieve the desired resolution and field of view configuration, simplifying the display hardware requirements.
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
Enables efficient power management and improved image quality by dynamically adjusting FOV and resolution, enhancing user experience across different use-cases without the need for extensive pixel density changes.
Implementation Method 1
a varifocal assembly configured to direct, through the eyebox, one of a first group of light beams having a first polarization state and one of a second group of light beams having a second polarization state
Implementation Method 2
an optical element configured to relay multiple light beams from the display to a viewer through an eyebox
Data Source
AI summary
A device includes a display including multiple pixels, each pixel having an optical emitter to provide at least one light beam from an image. The device also includes an optical element to relay light beams from the display to a viewer through an eyebox, the eyebox limiting an area that includes a pupil of the viewer and a varifocal assembly to direct, through the eyebox, light beams having a first and second mutually orthogonal polarization states, according to a desired mode of operation of the device, and associated with a first and second field of view of the image in a focused mode of operation of the device, and an immersive mode of operation of the device, respectively. A memory storing instructions and a processor to execute the instructions to cause the device to perform a method for adjusting between the immersive mode and the focused mode are also provided.