MEMS Actuation Using Bias Voltage and Pulse
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing micro-mechanical devices, such as micro mirrors in spatial light modulators, require high voltage pulses to tilt mirror plates, leading to complex and costly driving circuits, and variability in device properties complicates uniform actuation.
Innovation Solution
Applying a bias voltage in conjunction with a voltage pulse of lower amplitude to micro-mechanical devices, allowing for precise control of mirror plate tilt with reduced peak voltage requirements and addressing variability through optimized bias and pulse amplitude selection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high voltage pulses are applied to micro-mechanical devices to achieve reliable actuation, then the actuation reliability is improved, but the device complexity and cost of driving circuits increases
Solution Approach 1:
A bias voltage is applied in advance to the micro-mechanical device to pre-establish an electrostatic field between the movable electrode and the fixed electrode. This preliminary action reduces the additional voltage pulse amplitude required for actuation, thereby simplifying the driving circuit while maintaining reliable actuation. The bias voltage prepares the system so that only a small voltage swing is needed to overcome the mechanical restoring force.
Solution Approach 2:
The invention changes the voltage application parameters by introducing a DC bias voltage component and reducing the AC voltage pulse amplitude. Instead of applying a single high-amplitude voltage pulse, the system uses a combination of bias voltage and low-amplitude voltage pulse, where the total voltage V_total = V_bias + V_pulse. This parameter transformation allows reliable actuation with simplified driving circuits that only need to generate small voltage swings around the bias point.
2Force
If high voltage pulses are used to actuate micro-mechanical devices, then sufficient electrostatic force is generated, but energy consumption increases
Solution Approach 1:
The bias voltage is applied continuously to maintain a baseline electrostatic field, and only small voltage pulses are applied when actuation is needed. This preliminary establishment of the electrostatic field means that the full force requirement is not met by a large voltage swing but by a small perturbation around the bias point, significantly reducing the energy required for each actuation event.
Solution Approach 2:
Instead of continuously applying high voltage, the system uses periodic voltage pulses superimposed on a DC bias. The actuation occurs only during the brief pulse duration, while the bias voltage maintains the readiness state. This periodic application of control voltage reduces average power consumption compared to continuous high-voltage application.
3Ease of manufacture
If uniform voltage pulses are applied to all micro-mechanical devices, then circuit design is simplified, but devices with varying properties cannot be uniformly actuated
Solution Approach 1:
The invention applies a common bias voltage to all devices in the array, establishing a uniform baseline electrostatic field. This local quality approach allows each device to operate from the same reference point while accommodating individual variations through small adjustments in the voltage pulse amplitude. The bias voltage creates consistent initial conditions across all devices, enabling uniform actuation behavior despite manufacturing tolerances.
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
Simplifies the driving circuit by reducing the peak voltage needed for actuation and ensures consistent operation across micro-mechanical devices with varying properties, enhancing efficiency and reliability in spatial light modulators.
Implementation Method 1
The tilt movement of the mirror plate can be driven by electrostatic forces that can be generated by electric potential differences between a mirror plate and an electrode over the substrate underneath the mirror plate
Data Source
AI summary
Methods for driving a plurality of MEMS devices in an apparatus are described. A voltage pulse is applied to an electrode or a structure portion of a MEMS device. The electrode is on the substrate underneath the structure portion. At least two MEMS devices of the plurality of MEMS devices have different threshold voltages, and the threshold voltage is the minimum voltage required to move the structure portion. A bias voltage is applied to whichever of the electrode or the structure portion of the MEMS device does not have the voltage pulse applied thereto. The bias voltage and the voltage pulse are capable of moving the structure portion of the MEMS device that has the higher threshold voltage of the different threshold voltages.