MEMS Driver Resonant Frequency Detection via Amplitude Difference
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Solution Overview
Problem
In display devices using mirrors to direct a laser beam, changes in environmental conditions and wear and tear can alter the resonant frequency of MEMS drivers, leading to reduced efficiency and image distortion due to non-resonant frequency operation.
Innovation Solution
A display device with a nonlinear driver and fast-scan MEMS sensor system that detects amplitude and phase differences between the periodic electrical signal and the MEMS sensor output to determine the resonant frequency, allowing for dynamic adjustment of the driving frequency to match the MEMS driver's resonant frequency, using a signal generator and processor to iteratively update the frequency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the MEMS driver is driven at a fixed frequency, then the device operation is simple, but the efficiency decreases when resonant frequency changes due to environmental conditions and wear
Solution Approach 1:
The patent implements dynamic frequency adjustment by continuously monitoring the resonant frequency of the MEMS driver and adjusting the drive frequency accordingly. The processor determines resonant frequency changes based on amplitude differences between drive signals and sensor outputs, then dynamically updates the drive frequency to maintain optimal efficiency despite environmental changes and wear.
Solution Approach 2:
The system uses feedback from the MEMS sensor to detect resonant frequency changes. The sensor output is compared with the drive signal amplitude, and this feedback information is used by the processor to determine when resonant frequency has shifted, triggering an adjustment to the drive frequency to maintain optimal operation.
2Device complexity
If the MEMS driver is driven at a fixed frequency, then the control system is simple, but image distortion occurs when resonant frequency changes
Solution Approach 1:
The system dynamically adjusts the drive frequency based on real-time resonant frequency detection. When the processor detects a shift in resonant frequency through amplitude comparison, it updates the drive frequency to match the new resonant frequency, thereby preventing image distortion while maintaining relatively simple control logic.
Solution Approach 2:
The MEMS sensor provides feedback on the actual mirror position and resonant characteristics. This feedback loop allows the system to detect when resonant frequency has shifted and adjust the drive frequency accordingly, maintaining image quality without requiring complex predictive models or pre-calibration systems.
3Use of energy by moving object
If the drive frequency is adjusted to match resonant frequency, then energy efficiency improves, but the system complexity increases
Solution Approach 1:
The system performs self-diagnosis and self-adjustment by using the existing MEMS sensor to detect its own resonant frequency characteristics. The processor analyzes the amplitude difference between the drive signal and sensor output to determine resonant frequency shifts, and automatically adjusts the drive frequency without requiring external calibration equipment or complex diagnostic systems.
Solution Approach 2:
The MEMS sensor serves dual purposes: it acts as both the actuator's position sensor and the resonant frequency detector. This multi-functionality eliminates the need for separate diagnostic sensors or systems, reducing overall system complexity while enabling dynamic frequency adjustment for optimal energy efficiency.
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 solution ensures efficient operation of the MEMS driver by maintaining alignment with its resonant frequency, enhancing image clarity and reducing energy consumption by keeping the driver gain at a minimum.
Implementation Method 1
it is desirable for the MEMS driver to be driven at a frequency close to its resonant frequency... the resonant frequency of the MEMS driver may change over time
Data Source
AI summary
A display device is provided, including a laser beam emitter, a fast-scan driver system including a nonlinear driver and a fast-scan MEMS sensor, and a slow-scan MEMS driver. The nonlinear driver and the slow-scan MEMS driver may respectively drive a fast-scan mirror and a slow-scan mirror. The display device may further include a signal generator configured to generate a periodic electrical signal. The nonlinear driver may receive, amplify, and drive the fast-scan mirror with the amplified electrical signal. The fast-scan MEMS sensor may detect a motion of the fast-scan mirror. The display device may further include a signal detector configured to receive and detect an amplitude difference between a periodic electrical signal and a fast-scan MEMS sensor output signal. The display device may further include a processor configured to receive the amplitude difference and determine a driver system resonant frequency of the fast-scan driver system.