Sensor Element with Adjustable Electrodes for Angular Velocity Detection
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Solution Overview
Problem
Angular velocity sensors face challenges in achieving precise detection due to etching anisotropy and process variations, leading to inaccurate bending of tuning-fork elements and subsequent detection errors, which affect the accuracy of angular velocity detection.
Innovation Solution
The sensor element design includes a base part with drive and detection vibration arms, featuring a detection electrode and an adjustment electrode with branch parts that can be cut to adjust the sensor output, canceling out leakage outputs and achieving precise zero-point calibration, thereby enhancing detection sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If etching is used to form the tuning-fork element, then manufacturing is simplified, but manufacturing precision deteriorates due to etching anisotropy and process variations
Solution Approach 1:
The patent applies parameter changes by modifying the electrode configuration parameters (adding adjustment electrodes with branch parts) to compensate for manufacturing variations. By changing the electrical parameters (charge generation) rather than the physical geometry, the system achieves high precision without requiring ultra-precise manufacturing.
Solution Approach 2:
The patent implements feedback through the adjustment electrode system that generates compensating charge opposite in polarity to the detection electrode output. This feedback mechanism automatically corrects for manufacturing variations and asymmetries, allowing the use of standard etching processes while achieving high detection precision.
2Device complexity
If the tuning-fork element is formed by etching, then device complexity is reduced, but measurement precision deteriorates due to inaccurate bending direction
Solution Approach 1:
The adjustment electrode acts as an intermediary that mediates between the imperfect mechanical structure (caused by etching variations) and the detection requirement. It generates compensating electrical signals that correct the measurement error without requiring mechanical perfection.
Solution Approach 2:
The patent changes the measurement approach from purely mechanical (relying on precise arm bending) to electrical (using charge generation and cancellation). This parameter change allows standard etching processes to be used while achieving high measurement precision through electrical compensation.
3Measurement precision
If a portion of the detection electrode is removed to adjust charge output, then detection accuracy improves, but device complexity increases and adjustment precision deteriorates
Solution Approach 1:
Instead of removing parts of the detection electrode (subtraction approach), the patent adds adjustment electrodes that generate opposite polarity charge (addition approach). This inversion of the adjustment methodology simplifies the overall structure while achieving precise detection through charge cancellation.
Solution Approach 2:
The patent creates a composite electrode system combining detection electrodes and adjustment electrodes with different functions. This composite structure integrates both detection and calibration functions into a unified system, achieving high detection accuracy without increasing overall device 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 design allows for accurate adjustment of sensor output, improving detection sensitivity and reliability by compensating for manufacturing variations and ensuring precise angular velocity detection.
Implementation Method 1
each of the arms is provided with a driving section made of a pair of electrodes and a piezoelectric thin film sandwiched there the electrodes
Implementation Method 2
when the arms receive an angular velocity about their axis extending along the arm's longitudinal direction, the arms bend in a direction orthogonal to the driving direction due to Coriolis force, and a charge according to the amount of the bend is detected
Data Source
AI summary
A sensor element includes a base part, drive vibration arms that extend from the base part, an adjustment vibration arm 241 that extends from the base part and vibrates in response to drive vibration of the drive vibration arms, detection electrodes that output a signal according to a physical quantity applied to the drive vibration arms, and adjustment electrodes 551 and 553 provided on the adjustment vibration arm 241 and electrically connected to the detection electrodes for outputting a charge in a reverse polarity with respect to the detection electrodes in response to vibration of the adjustment vibration arm 241. The adjustment electrode 551 has a common part 60 electrically connected to the detection electrodes and a plurality of branch parts 61 branching out from the common part 60 and arranged side by side along an extension direction of the adjustment vibration arm 241.