MEMS Mirror Opening Angle Stabilization via Current Feedback
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Solution Overview
Problem
Current mirror driving techniques for MEMS devices fail to maintain a consistent opening angle due to changes in operating conditions or circuitry properties, such as temperature variations, affecting the precision of applications like wafer defect scanners and projectors.
Innovation Solution
An electronic device with a mirror controller that generates a drive control signal based on sensed feedback, using a sensing circuit to adjust the drive signal as a function of temperature and mechanical changes, ensuring the drive signal remains at a desired condition by converting current to voltage and adjusting digital representations to maintain a constant opening angle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If current mirror driving techniques are used, then the device operates with simple control circuitry, but the opening angle varies when operating conditions or circuitry properties change
Solution Approach 1:
The patent implements a feedback control mechanism where a sensing circuit monitors the actual drive signal characteristics (current or voltage) and feeds this information back to a mirror controller. The controller compares the sensed values against desired reference values and dynamically adjusts the drive control signal to maintain the desired opening angle despite temperature variations or circuit property changes. This closed-loop feedback system directly resolves the contradiction by ensuring opening angle consistency through continuous monitoring and correction.
Solution Approach 2:
The patent compensates for operating condition changes by dynamically adjusting drive signal parameters (current or voltage) based on sensed feedback. When temperature or circuit properties change, the system modifies the drive signal magnitude to counteract these changes and maintain a constant opening angle. This parameter adjustment approach allows the system to adapt to varying conditions while preserving the desired optical performance.
2Stability of the object's composition
If temperature compensation is implemented, then the opening angle remains constant across temperature variations, but the device complexity increases
Solution Approach 1:
The sensing circuit continuously monitors the drive signal characteristics and feeds this information back to the mirror controller, which automatically adjusts the drive signal to compensate for temperature-induced changes. This real-time feedback mechanism provides temperature compensation without requiring separate temperature sensors or complex thermal management systems, as the drive signal itself serves as the compensation reference.
Solution Approach 2:
The system uses the existing drive signal characteristics as the basis for temperature compensation, eliminating the need for separate temperature sensing or compensation circuitry. The sensing circuit monitors the drive signal properties that inherently reflect temperature effects, and the controller self-adjusts the drive parameters to maintain constant opening angle, allowing the system to compensate for temperature variations using its own operational parameters.
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
The solution effectively maintains a consistent mirror opening angle across varying temperatures and mechanical conditions, enhancing the precision and reliability of MEMS-based scanning devices by using real-time feedback and adaptive control mechanisms.
Implementation Method 1
the sensing circuit may include a current to voltage converter configure to convert the current value of the drive signal to a voltage
Implementation Method 2
The actuation of mirrors used in MEMS devices, referred to herein as MEMS mirrors, can be via the electromagnetic, electrostatic, piezoelectric, and thermoelectric effects
Data Source
AI summary
An electronic device disclosed herein includes a mirror controller configured to generate a drive control signal, with a drive circuit configured to generate a drive signal for a movable mirror based upon the drive control signal. A sensing circuit is configured to sense the drive signal. The mirror controller is further configured to adjust the drive control signal as a function of the sensed drive signal.