Scanning Reflector System Nonlinear Vibration Control
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Solution Overview
Problem
Scanning MEMS reflector systems face challenges in achieving broadened image areas due to high Q-values, which result in narrow bandwidths and difficulties in rapidly changing tilt angles, limiting the introduction of modulation signals for 2-dimensional image formation.
Innovation Solution
A feedback circuit is configured to drive the reflector system into a nonlinear vibration range, utilizing frequency response phenomena to enable image area broadening modulation by adjusting amplitude and frequency to a non-linear range where the frequency shift at the peak frequency is at least ten times the initial bandwidth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the reflector is vacuum packaged to achieve high Q-values (1000-10000), then the tilt angle can be large with practical drive voltages, but the bandwidth becomes very narrow and the transient response time increases
Solution Approach 1:
The patent applies nonlinear dynamics by driving the reflector into a non-linear vibration range where the frequency shift at peak frequency is at least ten times the initial bandwidth. This dynamic approach allows the system to overcome the narrow bandwidth limitation imposed by high Q-values while maintaining large tilt angles with practical drive voltages.
Solution Approach 2:
The patent changes the operating parameters by adjusting the drive amplitude and frequency into a non-linear range. This parameter change transforms the system's frequency response characteristics, creating a broadened image area and enabling modulation signals for 2-dimensional image formation without sacrificing the high Q-value benefit.
2Ease of operation
If the reflector is driven at resonant frequency with high Q-value, then large tilt angles are achieved with practical voltages, but modulation signals cannot be introduced for 2-dimensional image area
Solution Approach 1:
The patent transitions from linear resonant operation to nonlinear vibration operation. By driving the reflector into a non-linear range with frequency shift at peak frequency at least ten times the initial bandwidth, the system gains adaptability to introduce modulation signals while maintaining ease of operation with practical drive voltages.
Solution Approach 2:
The patent modifies the operating parameters (amplitude and frequency) into a non-linear range, which transforms the frequency response to enable both large tilt angles with practical voltages and the introduction of modulation signals for 2-dimensional image formation.
3Adaptability or versatility
If the frequency shift at peak frequency is increased to broaden image area, then modulation signals can be introduced, but the system moves into non-linear range with potential instability
Solution Approach 1:
The patent employs a feedback circuit to control the reflector system. This feedback mechanism stabilizes the nonlinear vibration operation, allowing the frequency shift at peak frequency to be at least ten times the initial bandwidth while preventing the instabilities that would normally occur in non-linear ranges.
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 allows for controlled modulation of tilt angles and increased image area while maintaining high Q-values, enabling efficient 2-dimensional scanning with applicable drive voltages and reduced transient response times.
Implementation Method 1
a spring structure (304, 306, 308) suspending the reflector (302) to a support (300) for scanning motion
Implementation Method 2
a first transducer structure (301) for actuation of the reflector (302) according to a drive signal
Implementation Method 3
Both oscillations can be excited and driven simultaneously, and the resulting position of the reflector is a superposition of the two oscillation modes. The reflector is thereby made to undergo scanning motion in two orthogonal oscillation modes. Advantageously these oscillation modes are operated resonantly.
Data Source
AI summary
An apparatus includes a reflector system having a support, a reflector and a spring structure for scanning motion of the reflector in two orthogonal oscillation modes. A frequency response peaks at a natural resonant frequency with an initial bandwidth. A first transducer structure provides mechanical actuation of the reflector; a second transducer structure generates sense signals representing mechanical motion of the reflector. A feedback circuit receives from the second transducer structure a sense signal and generates to the first transducer structure a drive signal. The feedback circuit is adjusts amplitude and frequency of the drive signal to a non-linear vibration range where a frequency shift at the peak frequency is at least ten times the initial bandwidth, varies the amplitude of the drive signal in proportion to a waveform of a modulation signal, and sets frequency of the modulation signal component smaller than the frequency shift at the peak frequency.