MEMS Mirror Speed Control for Foveated Laser Display

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Solution Overview

Problem

Conventional scanning display devices consume significant power and increase processing costs by maintaining uniform pixel density across entire images, which is inefficient as human vision prioritizes higher resolution in the foveal region and lower resolution in non-foveal regions.

Innovation Solution

Implementing a scanning display system with dynamically adjustable MEMS mirror rotation speeds in the slow-axis direction to vary line densities within an image, using eye-tracking to determine the foveal region and adjusting pixel data to ensure consistent brightness across regions, thereby reducing power consumption and processing load.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If uniform pixel density is maintained across the entire image, then image quality is consistent throughout, but power consumption and processing costs increase significantly

Engineering Contradiction:
Improveimage quality consistencyVSAvoidpower consumption
Core Design Contradiction:
Manufacturing precisionVSUse of energy by moving object

Solution Approach 1:

The patent applies local quality by varying the pixel density across different regions of the display. The foveal region (center of visual attention) receives higher pixel density with more lines per unit area, while peripheral regions use lower pixel density. This resolves the contradiction by providing high image quality only where the human eye can actually perceive it, rather than uniformly across the entire display, thereby reducing overall power consumption and processing requirements.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent implements dynamics by making the high-density region movable and adjustable based on eye tracking data. The foveal region can be dynamically repositioned to follow the user's gaze, and the pixel density distribution can be adjusted in real-time. This allows the system to maintain high image quality in the relevant region while keeping power consumption low in irrelevant regions, resolving the contradiction between consistent quality and energy efficiency.

Inventive Principle:
Principle #15Dynamics

2Measurement precision

If pixel density is increased throughout the entire image to improve resolution, then image resolution improves, but processing costs and power consumption increase

Engineering Contradiction:
Improveimage resolutionVSAvoidprocessing efficiency
Core Design Contradiction:
Measurement precisionVSProductivity

Solution Approach 1:

The patent applies local quality by concentrating high pixel density only in the foveal region where the human eye has highest acuity, while using lower pixel density in peripheral regions. This resolves the contradiction by providing high image resolution only where it is perceptually necessary, rather than uniformly across the entire image, thereby reducing the total number of pixels that need to be processed and displayed, which improves processing efficiency while maintaining perceived image quality.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent implements partial action by applying high pixel density only to the necessary portion of the image (the foveal region) rather than the entire image. The eye tracking system identifies the relevant region and concentrates processing resources there, using partial rather than full high-resolution rendering across the whole display, thus improving processing efficiency while maintaining image resolution where it matters most.

Inventive Principle:
Principle #16Partial or excessive action

3Use of energy by moving object

If line density is varied across different regions of the image, then power consumption is reduced, but brightness uniformity across the image becomes challenging

Engineering Contradiction:
Improvepower consumptionVSAvoidbrightness uniformity
Core Design Contradiction:
Use of energy by moving objectVSIllumination intensity

Solution Approach 1:

The patent applies parameter changes by adjusting not only the line density but also the brightness parameters of pixels in different regions. The system compensates for the lower line density in peripheral regions by adjusting brightness levels to maintain perceived uniformity. This resolves the contradiction by using multiple adjustable parameters (line density and brightness) in combination rather than relying on line density alone, thereby reducing power consumption while maintaining brightness uniformity across the image.

Inventive Principle:
Principle #35Parameter changes

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 reduces power consumption and processing requirements by dynamically adjusting line densities and brightness compensation, enhancing image quality by prioritizing higher resolution in the foveal region while maintaining lower resolution in non-foveal areas.

Implementation Method 1

one or more MEMS mirrors, a speed at which one of the one or more MEMS mirrors is rotated

Methodology Applied
Scientific EffectMEMS (Microelectromechanical Systems): MOEMS

Implementation Method 2

light source that produces a light beam that is reflected by the mirror(s)... one or more light emitting elements (e.g., laser diodes)

Methodology Applied
Scientific EffectLight emission from laser diodes: Light Emitting Diode

Implementation Method 3

Light corresponding to the image that is coupled into the one or more optical waveguides via the input-coupler(s)... travels at least in part by way of total internal reflection (TIR) from the input-coupler(s) to the output-coupler(s)

Methodology Applied
Scientific EffectTotal internal reflection: Total Internal Reflection

Data Source

PatentEP3602536B1Laser scan beam foveated display
Publication Date: 2021.04.21 MICROSOFT TECHNOLOGY LICENSING LLC
  • EP3602536B1 patent drawingFigure 1
  • EP3602536B1 patent drawingFigure 2A
  • EP3602536B1 patent drawingFigure 2B

AI summary

An apparatus includes one or more MEMS mirrors, a light source driver and a controller. The light source driver selectively drives one or more light emitting elements of a light source to thereby produce a light beam that is directed towards a same MEMS mirror. The controller controls rotation of the MEMS mirror(s) in a fast-axis direction and a slow-axis direction in order to raster scan an image using the light beam reflected from the MEMS mirror(s). In order to achieve a first line density in a first portion of the image being raster scanned and to achieve a second line density, that is less than the first line density, in a second portion of the image being raster scanned, the controller dynamically adjusts a speed at which one of the MEMS mirror(s) is rotated in the slow-axis direction. Related systems and methods are also disclosed herein.