MEMS Driver Circuit with Supply Tracked Common Mode Voltage
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional MEMS scanning mirror drivers using sinusoidal waveforms suffer from discontinuities (dead zones) at resonance, requiring frequent recalibration due to voltage variations, leading to operational inefficiencies and increased costs.
Innovation Solution
A motor driver circuit comprising a non-inverting buffer circuit, an inverting buffer circuit, and a scalar circuit with a Supply Tracked Common Mode Voltage (VCMSC) generation circuit, which provides a common mode voltage to the motor, automatically tracking variations in supply voltage and scalar gain, ensuring linear motor current versus control voltage characteristics without dead zones.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If sinusoidal waveforms are used to actuate MEMS scanning mirrors, then the mirrors can be driven at resonance, but discontinuities (dead zones) occur when the mirrors are at resonance
Solution Approach 1:
The patent changes the waveform parameter from sinusoidal to triangular waveform. This parameter change eliminates the dead zones that occur with sinusoidal waveforms at resonance, while still allowing the MEMS scanning mirror to be driven at resonant frequencies for high-speed scanning operation.
2Device complexity
If conventional circuit architectures are used to drive MEMS scanning mirrors, then the system is simple, but frequent recalibration is required due to supply voltage variations
Solution Approach 1:
The patent implements a feedback mechanism where the triangular waveform generator is controlled by a controller that monitors the mirror position and adjusts the waveform accordingly. This feedback loop compensates for supply voltage variations, eliminating the need for frequent recalibration while maintaining system stability.
Solution Approach 2:
The system performs self-calibration by using the controller to automatically adjust the triangular waveform parameters based on detected mirror position and supply voltage conditions. This self-service capability eliminates the need for manual recalibration operations.
3Device complexity
If sinusoidal waveforms are used to drive MEMS scanning mirrors, then the driving mechanism is simple, but dead zones prevent data encoding and decoding
Solution Approach 1:
The patent changes the driving waveform from sinusoidal to triangular, which eliminates dead zones. This allows continuous data encoding and decoding to occur during scanning operations, preventing information loss while maintaining a relatively simple driving mechanism through the use of a triangular waveform generator.
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 enables bidirectional high current drivability, linear motor current control, and adjustable image projection size, maintaining image quality while operating independently of supply voltage variations, eliminating the need for frequent recalibration.
Implementation Method 1
the VCMSC voltage is generated by the VCMSC generation circuit in response to a control supply voltage and a driver supply voltage provided to the VCMSC generation circuit
Implementation Method 2
These scanning mirrors are actuated by electrostatic or electromagnetic forces
Implementation Method 3
These scanning mirrors are actuated by electrostatic or electromagnetic forces to reflect incident light beam from a laser source in order to project 2D image patterns onto a surface
Data Source
AI summary
A motor driver circuit for a Micro-electro-mechanical systems (MEMS) micro-mirror device, the motor driver circuit comprising: a non-inverting buffer circuit; an inverting buffer circuit; and a scalar circuit, the scalar circuit comprising a Supply Tracked Common Mode Voltage (VCMSC) generation circuit, wherein the non-inverting buffer circuit, the inverting buffer circuit, and the scalar circuit are configured, together with the VCMSC generation circuit, to provide a common mode voltage to a motor in response to a VCMSC voltage generated by the VCMSC generation circuit, and wherein the VCMSC voltage is generated by the VCMSC generation circuit in response to a control supply voltage and a driver supply voltage provided to the VCMSC generation circuit.