Content-Adaptive Vector Scanning for Waveguide AR Displays
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Solution Overview
Problem
Existing head-mounted display systems face challenges in achieving high brightness, power efficiency, and reduced power consumption while maintaining a small form factor due to limitations in raster and Lissajous scanning techniques, which require high electrical power and laser damage thresholds, especially in waveguide-based systems with low optical efficiencies.
Innovation Solution
Implementing vector scanning techniques that steer a light beam according to a content-dependent scan path, optimizing scan paths with curves or loops, and controlling beam width and brightness to minimize power consumption and increase dwell time, thereby reducing the need for high optical output power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If raster or Lissajous scanning techniques are used, then the display system can cover the entire field of view, but the electrical power consumption increases and the system requires higher laser damage thresholds
Solution Approach 1:
The patent extracts only the necessary portions of the field of view by identifying and displaying only relevant content regions rather than scanning the entire field of view. This is achieved by determining a region of interest and directing the light beam only to areas containing actual content, thereby eliminating power consumption associated with scanning empty or irrelevant regions.
Solution Approach 2:
The patent applies partial action by scanning only the necessary portions of the display area where content actually exists. Instead of performing complete raster or Lissajous scanning across the entire field of view, the system performs scanning only in regions containing content, reducing overall power consumption while maintaining display functionality.
2Reliability
If raster or Lissajous scanning techniques are used, then the display system can maintain consistent scanning coverage, but the device size and power requirements increase
Solution Approach 1:
The patent transitions from static, fixed-pattern scanning (raster or Lissajous) to dynamic, content-adaptive scanning. The scanning pattern is continuously adjusted based on the actual content being displayed, allowing the system to optimize its scanning behavior for each frame while maintaining reliable display performance. This dynamic approach reduces complexity by adapting to content rather than requiring complex fixed-pattern hardware.
3Illumination intensity
If the light beam is continuously on during scanning, then the display brightness is maintained, but the power consumption increases
Solution Approach 1:
The patent implements periodic action by turning the light beam on only during the intervals when the scanner is actually displaying content and turning it off during transition periods between content regions. This periodic on-off operation maintains display brightness during active scanning while eliminating power waste during transitions, directly addressing the contradiction between continuous illumination and power efficiency.
4Speed
If the scanner moves quickly between scan lines, then the refresh rate is maintained, but the dwell time at each pixel decreases reducing brightness
Solution Approach 1:
The patent ensures continuity of useful action by keeping the light beam continuously on during content display intervals without unnecessary interruptions. By eliminating repeated on-off transitions during content scanning and only turning the beam off during actual transitions between content regions, the system maintains continuous illumination on displayed content, increasing effective dwell time and pixel brightness while preserving high scan speeds for frame refresh.
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
Vector scanning achieves higher brightness and power efficiency by optimizing scan paths, reducing power consumption, and enhancing brightness uniformity across the eyebox, while maintaining a compact form factor.
Implementation Method 1
a scanner configured to steer the light beam
Implementation Method 2
a waveguide display configured to receive the light beam from the scanner and direct the light beam towards an eyebox
Data Source
AI summary
A method of displaying images by vector scanning in a head-mounted display includes determining, based on content of an image to be displayed by the head-mounted display, a vector scanning pattern for displaying the image, the vector scanning pattern including a plurality of scan lines and one or more transition lines connecting the plurality of scan lines, at least one transition line of the one or more transition lines including a curved section (or loop); generating control signals for controlling a scanner to steer, according to the vector scanning pattern, a light beam emitted by a light source towards a waveguide display of the head-mounted display; and generating modulation signals for modulating the light source such that the light beam is turned on when the scanner operates according to the plurality of scan lines and is turned off when the scanner operates according to the one or more transition lines.