Vibrating Reed Groove Electrode Design for Gyro Sensor Sensitivity
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Solution Overview
Problem
Miniaturization of gyro sensors leads to a decrease in detection sensitivity due to weaker electric fields generated in response to angular velocity, as the area of electrodes is reduced, and electric charge loss occurs when the detection unit vibrates along the thickness direction.
Innovation Solution
A vibrating reed design with a groove that extends beyond the midline of the piezoelectric body's main surfaces, featuring inside and outside surface electrodes and groove bottom electrodes positioned to maintain the same electric field direction, preventing electric charge loss and allowing for enlarged electrode areas, thereby enhancing detection sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the area of electrodes is reduced due to miniaturization of gyro sensors, then the size of the sensor is reduced, but the detection sensitivity decreases due to weaker electric fields
Solution Approach 1:
The invention transitions from planar electrode arrangement to three-dimensional electrode arrangement by extending electrodes into grooves that penetrate the thickness direction of the detection unit. This dimensional change allows electrodes to be positioned at multiple depths (first main surface, groove bottom, second main surface), effectively increasing the electrode area and electric field generation capability without increasing the planar footprint of the sensor.
Solution Approach 2:
The invention nests electrodes within grooves that are formed inside the detection unit structure. The grooves contain inside surface electrodes and groove bottom electrodes that are positioned within the thickness direction of the detection unit, allowing electrode functionality to be embedded within the existing structural volume rather than requiring additional external space.
2Area of stationary object
If a groove is provided open to the main surface of the detection unit to enlarge electrode area, then the electrode area can be increased, but electric charge loss occurs when the detection unit vibrates along the thickness direction
Solution Approach 1:
The invention introduces asymmetry in the electrode arrangement by positioning the groove bottom at a specific depth that is beyond the midline between the first and second main surfaces. This asymmetric positioning ensures that during vibration along the thickness direction, the groove bottom electrode remains on the same side of the midline, maintaining consistent electric field direction and preventing charge loss that would occur with symmetric or surface-level groove configurations.
Solution Approach 2:
The invention applies different electrode configurations to different regions of the detection unit. The groove bottom electrode is positioned at a specific depth region (beyond the midline) while inside surface electrodes are positioned at other regions. This localized electrode placement optimizes each region's contribution to electric field generation while minimizing charge loss during vibration.
3Measurement precision
If the distance between electrodes is narrowed to improve electric field efficiency, then the electric field efficiency improves, but the electrode area is reduced
Solution Approach 1:
The invention resolves this contradiction by utilizing the thickness direction (Z-axis) to increase electrode area without compromising electric field efficiency. By positioning electrodes at different depths (first main surface, groove bottom beyond midline, second main surface), the effective electrode area is increased through three-dimensional arrangement, while the electric field efficiency is maintained through optimized spacing in the thickness direction.
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 effectively improves detection sensitivity by maintaining electric field efficiency and preventing charge loss, even when the vibrating reed is miniaturized, allowing for more accurate angular velocity detection without adverse effects from external noise.
Implementation Method 1
a compressive force is applied to one of two areas divided from each other by the midline in the thickness direction, and a tensile force is applied to the other of the two areas in the detection unit that vibrates along the thickness direction... Electric fields generated in response to the compressive force or the tensile force act in the pair of electrodes formed in the detection unit
Implementation Method 2
the pair of groove bottom electrodes that is provided further on the groove bottom side than the midline at an interval and face inside the groove... maintaining the same electric field direction, preventing electric charge loss
Implementation Method 3
when an angular velocity motion about the Y axis is applied to a vibrating reed extending in the Y direction, a drive unit that is subjected to an in-plane vibration in the X direction in the X-Y plane is then changed to be subjected to an out-of-plane vibration in the Z axis direction (the thickness direction of the vibrating reed) by the action of the Carioles force
Data Source
AI summary
The vibrating reed includes a first main surface and a second main surface that face each other in the thickness direction of a piezoelectric body and a detection unit that vibrates along the thickness direction when detecting. The detection unit includes a groove of which a groove bottom is positioned at a position beyond a midline between the first main surface and the second main surface in the depth direction from an opening formed in the first main surface, an inside surface electrode that is formed on an inside surface facing the inside of the groove, an outside surface electrode that is formed on an outside surface which is opposite the inside surface with the piezoelectric body interposed there between, and a pair of groove bottom electrodes that is provided further on the groove bottom at an interval than the midline and face inside the groove.