MEMS Scanner Position Sensing via Drive Signal
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Solution Overview
Problem
Conventional MEMS devices require additional components and space for accurate determination of scanner position, such as photodetectors and sensor comb fingers, which consume valuable space and complicate the system.
Innovation Solution
The MEMS device employs drive electronics to generate a drive signal at a frequency equal to the scanner's resonant frequency or a sub-harmonic frequency, allowing sensing electronics to determine the scanner's position only when drive-signal pulses are not being transmitted, eliminating the need for additional components like photodetectors and dedicated sensor comb fingers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If photodetectors or sensor comb fingers are added to determine scanner position, then measurement precision is improved, but device complexity and space consumption increase
Solution Approach 1:
The scanner utilizes its own drive signal as the sensing signal. The drive electronics generate a drive signal that causes the scanner to oscillate, and the same or integrated electronics detect the scanner's position by monitoring characteristics of this drive signal during periods when the scanner is not being actively driven. This self-service approach eliminates the need for separate photodetectors or sensor comb fingers, reducing device complexity while maintaining measurement precision.
Solution Approach 2:
The drive electronics perform dual functions: generating the drive signal to oscillate the scanner and simultaneously serving as the sensing electronics to determine scanner position. By making the drive electronics universal, the patent eliminates dedicated sensing components, thereby reducing device complexity and space consumption while achieving accurate position determination.
2Measurement precision
If photodetectors or sensor comb fingers are added to determine scanner position, then measurement precision is improved, but the area of the MEMS die increases
Solution Approach 1:
The scanner system uses its own drive signal for position sensing, eliminating the need for additional sensing components that would consume valuable MEMS die area. The drive electronics are configured to both drive and sense, making the system self-sufficient and space-efficient.
Solution Approach 2:
The drive electronics perform both driving and sensing functions, consolidating what would traditionally require separate components. This multi-functionality approach significantly reduces the area required on the MEMS die, as no additional photodetectors or sensor comb fingers need to be fabricated.
3Measurement precision
If additional components are added for position sensing, then measurement precision is improved, but manufacturing complexity increases
Solution Approach 1:
The system uses its own drive signal for sensing purposes, eliminating the need for additional manufacturing steps to create separate sensing components. This self-service approach simplifies the manufacturing process while maintaining accurate position determination.
Solution Approach 2:
The drive electronics are designed to perform both driving and sensing functions, reducing the number of components that need to be manufactured and assembled. This universality approach simplifies the overall manufacturing process and reduces production complexity.
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 enables accurate determination of the scanner's rotational position without additional components, reducing space consumption and system complexity while maintaining precise scanning capabilities.
Implementation Method 1
the drive frequency is selected to be about equal to the characteristic resonant frequency or a sub-harmonic frequency of the resonant frequency
Data Source
AI summary
Embodiments relate to a MEMS device including a scanner rotatable about at least one rotation axis, with the scanner having a characteristic resonant frequency. According to one embodiment, the MEMS device includes drive electronics operable to generate a drive signal that causes the scanner to oscillate at an operational frequency about the at least one rotation axis. The drive signal has a drive frequency selected to be about equal to the characteristic resonant frequency or a sub-harmonic frequency of the characteristic resonant frequency. According to another embodiment, the drive electronics are operable to generate a drive signal having a plurality of drive-signal pulses that moves the scanner at an operational frequency and sensing electronics are operable to sense a position of the scanner only when the drive-signal pulses of the drive signal are not being transmitted by the drive electronics. The MEMS device embodiments may be incorporated in scanned beam imagers, endoscopes, and displays.