Mirror Control Device Bias Voltage Drift Suppression
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional mirror control devices exhibit a change in driving voltage vs. tilt angle characteristic depending on pivot direction due to central position shifts, electrode shape errors, and stiffness differences, leading to cumbersome control and drift issues.
Innovation Solution
A mirror control device with bias voltage generation and AC driving voltage application to maintain a uniform tilt angle characteristic across pivot directions, reducing the need for directional voltage adjustments and minimizing drift by using AC voltages with zero average DC components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If DC voltages are applied to the electrodes to control the mirror tilt angle, then the mirror can be driven to the desired position, but charge accumulates in the stray capacitance causing drift over time
Solution Approach 1:
The patent applies AC voltages with different phases to the electrodes instead of DC voltages. By using periodic AC signals, the charge accumulation in stray capacitance is prevented because the alternating polarity continuously discharges any accumulated charge, thereby eliminating drift while maintaining precise tilt angle control through phase and amplitude modulation.
2Force
If high driving voltages are applied to achieve the required tilt angle, then the mirror can be driven against the restoring force of torsion springs, but the power consumption increases and high voltage power supplies are required
Solution Approach 1:
The patent changes the voltage application parameters by using AC voltages with optimized amplitudes and phases. This allows achieving the required electrostatic attraction force with lower voltage amplitudes compared to conventional DC driving, reducing power consumption while maintaining adequate driving force to overcome the torsion spring restoring force.
3Ease of operation
If asymmetrical potential differences are applied to correct the driving voltage vs. tilt angle characteristic difference, then uniform control can be achieved, but the control system becomes more complex
Solution Approach 1:
The patent applies asymmetrical potential differences and phase shifts in advance during the design and calibration stage. By pre-adjusting the voltage parameters to compensate for manufacturing tolerances and mechanical asymmetries, the system achieves uniform control characteristics without requiring complex real-time adjustment mechanisms, thus simplifying the overall control system.
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 achieves a uniform driving voltage vs. tilt angle characteristic, reduces drift by canceling accumulated charges, and allows for lower driving voltages, enabling the use of lower power supplies and increased driving force.
Implementation Method 1
Positive driving voltages are applied to the electrodes 340a to 340d such that asymmetrical potential differences are generated between them, thereby attracting the mirror 230 by an electrostatic attraction and making it pivot in an arbitrary direction.
Data Source
AI summary
A mirror control device includes a pivotally supported mirror (230), electrodes (340a-340d) spaced apart from the mirror (230), a driving voltage generation means (401) for generating a driving voltage corresponding to the desired tilt angle of the mirror (230) for each electrode, a bias voltage generation means (402) for generating, as a bias voltage for each electrode, a voltage which causes the tilt angle of the mirror (230) to have the same predetermined value upon being independently applied to each of the electrodes (340a-340d), and an electrode voltage applying means (403) for adding, for each electrode, the bias voltage to the driving voltage and applying the voltage after addition to a corresponding one of the electrodes (340a-340d).