Doubly Rotated Quartz Resonator Layout for Low Acceleration Sensitivity
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Solution Overview
Problem
Quartz crystal resonators and oscillator devices are sensitive to mechanical acceleration, which affects the stability of frequency reference and timing signals in applications where significant mechanical acceleration is present.
Innovation Solution
Doubly rotated quartz crystal resonators are manufactured with an in-plane non-zero angle rotation around the yI axis, positioning the line of geometrical symmetry at an angle relative to the crystallographic z axis, reducing sensitivity to mechanical acceleration by applying an in-plane rotation within the range of 36° to 56° during the cutting of quartz plates into individual resonating elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If quartz crystal resonators are mounted using conventional cantilever mounting arrangements, then ease of manufacture is improved, but sensitivity to mechanical acceleration increases
Solution Approach 1:
The patent applies asymmetry by rotating the resonating element at a non-zero angle within the xI-yI plane, positioning it at an angle between 0° and 45° relative to the xI axis. This asymmetric angular positioning breaks the symmetry of the conventional mounting arrangement, creating a configuration where the principal stress axes of the resonating element are no longer aligned with the mounting structure, thereby reducing sensitivity to mechanical acceleration while preserving manufacturing simplicity
Solution Approach 2:
The patent changes the angular parameter of the resonating element's orientation within the xI-yI plane from the conventional 0° (aligned with xI axis) to a non-zero angle between 0° and 45°. This parameter change in the mounting configuration modifies how mechanical stresses are distributed and transmitted to the resonating element, reducing acceleration sensitivity without complicating the manufacturing process
2Ease of manufacture
If the line of geometrical symmetry is positioned perpendicular to the crystallographic z axis, then conventional manufacturing processes are used, but acceleration sensitivity increases
Solution Approach 1:
The patent introduces asymmetry by deliberately positioning the line of geometrical symmetry at a non-perpendicular angle to the crystallographic z axis. This asymmetric orientation decouples the resonating element's stress response from the mounting structure's acceleration forces, improving frequency stability under mechanical stress while remaining compatible with conventional manufacturing processes
Solution Approach 2:
The patent modifies the angular parameter of the line of geometrical symmetry relative to the crystallographic z axis from 90° (perpendicular) to a non-perpendicular angle. This parameter change in orientation alters the stress distribution characteristics, reducing the coupling between mechanical acceleration and resonant frequency, thereby improving reliability without requiring new manufacturing methods
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 significantly reduces the sensitivity to mechanical acceleration, achieving total acceleration sensitivity below 1 ppb/g for cantilever-mounted SC cut resonators, thereby enhancing the stability of frequency control products like crystal oscillators and temperature-compensated oscillators.
Implementation Method 1
The quartz crystal resonating element is typically made from a quartz plate
Implementation Method 2
High frequency stability electronic oscillators are often built with quartz crystal resonators
Data Source
AI summary
A doubts rotated quart/crystal resonator comprises a cantilever-mounted doubts rotated resonating element having a line of geometrical symmetry running from a supported end to a free end which is not perpendicular to the resonating element's crystallographic/axis. A method of manufacturing the crystal resonator comprises cutting a doubly rotated quartz crystal plate with xI and zI axes defining the plate's plane into one or more resonating elements at a non-zero degrees in-plane rotation angle in relation to the plate's xI axis. The resonator has reduced sensitivity to mechanical acceleration.