Laser Scanning Mirror Resonant Frequency Control via Feedback

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Solution Overview

Problem

Existing laser beam scanning display devices face inefficiencies due to changes in resonant frequency of MEMS drivers, leading to image distortion and high computational and power consumption, as well as complex control architectures that struggle to maintain optimal stability and image quality.

Innovation Solution

A controller dynamically controls the resonant frequency of mirrors by receiving feedback signals and adjusting input signals to minimize the difference between the current and target resonant frequencies, allowing components to operate autonomously without complex coordination between control loops.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If multiple controllers coordinate to detect and accommodate changes in resonant frequency, then the resonant frequency can be tracked, but the device complexity and computational resources increase significantly

Engineering Contradiction:
Improveresonant frequency trackingVSAvoidcontrol architecture complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The single controller autonomously monitors the resonant frequency of the MEMS driver and automatically adjusts the drive frequency to match the detected resonant frequency, eliminating the need for multiple coordinating controllers and reducing system complexity while maintaining reliable frequency tracking

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The single controller performs multiple functions including driving the MEMS mirror, monitoring resonant frequency changes, determining the current resonant frequency, and adjusting the drive frequency, consolidating the roles of multiple specialized controllers into one multi-functional unit

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Reliability

If multiple controllers communicate to maintain resonant frequency, then frequency accuracy can be maintained, but power consumption increases

Engineering Contradiction:
Improvefrequency accuracyVSAvoidpower consumption
Core Design Contradiction:
ReliabilityVSUse of energy by moving object

Solution Approach 1:

The single controller independently performs frequency monitoring and adjustment without requiring continuous communication and coordination with other controllers, reducing the computational overhead and power consumption associated with inter-controller communication while maintaining accurate frequency tracking

Inventive Principle:
Principle #25Self-service

3Reliability

If complex coordination between controllers is implemented, then resonant frequency can be controlled, but control efficiency decreases

Engineering Contradiction:
Improveresonant frequency controlVSAvoidcontrol efficiency
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The single controller directly and immediately adjusts the drive frequency in response to detected resonant frequency changes without requiring coordination delays or communication overhead, maximizing control efficiency while maintaining reliable frequency control

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

Instead of having multiple controllers attempt to coordinate and agree on frequency adjustments, the system inverts the approach by having one controller unilaterally control the frequency, eliminating coordination bottlenecks and improving response time

Inventive Principle:
Principle #13The other way round (Inversion)

Data Source

PatentEP3935429B1Control loop for stabilizing a resonant frequency of a mirror of a laser beam scanning display
Publication Date: 2025.07.30 MICROSOFT TECHNOLOGY LICENSING LLC
  • EP3935429B1 patent drawingFigure 1
  • EP3935429B1 patent drawingFigure 2
  • EP3935429B1 patent drawingFigure 3

AI summary

A laser beam display device that can dynamically control the resonant frequency of a mirror is provided. The increase the reliability of a device by controlling the resonant frequency of a mirror instead of requiring components of a display device to react to changes in the resonant frequency of a mirror. A controller can drive a mirror with an input signal, receive a signal or data indicating a target resonant frequency, and bias the input signal to control the resonant frequency of the mirror. In some embodiments, the controller can also receive a feedback signal from a mirror indicating a current resonant frequency. The controller can also bias the input signal to increase or decrease the current resonant frequency. By dynamically controlling the resonant frequency of a mirror, a device can minimize any difference between the current resonant frequency detected in a feedback signal and the target resonant frequency.