Crystal Resonator Shear-Mode Layout for Low G-Sensitivity
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Solution Overview
Problem
Conventional crystal resonators experience frequency shifts due to external accelerations, leading to undesired oscillation effects.
Innovation Solution
A crystal resonator design with a crystal plate featuring a first and second vibration section, connected along an oscillating direction, and an electrode set applying voltages with opposite polarities to induce thickness shear mode oscillations, reducing the g-sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional crystal resonator is used with electrodes disposed on two sides of the crystal plate, then the resonator can provide steady signal oscillation at a specific frequency, but the resonator experiences frequency shifts when affected by external inertial forces such as acceleration, tilt, or shock
Solution Approach 1:
The crystal plate is divided into a first vibration section and a second vibration section that are connected and arranged along an oscillating direction not parallel to the thickness direction. Each section has electrodes applied with opposite polarities, creating independent vibration control that compensates for acceleration effects and reduces g-sensitivity while maintaining signal stability.
Solution Approach 2:
The oscillating direction is changed from the conventional thickness direction to a direction not parallel to the thickness direction. This dimensional change enables the crystal plate to exhibit thickness shear mode vibration, which inherently provides lower g-sensitivity while maintaining reliable signal oscillation.
2Device complexity
If the crystal plate oscillates in the thickness direction with conventional electrodes, then the resonator structure is simple, but the oscillation signal frequency shifts under external acceleration
Solution Approach 1:
The oscillation is shifted from the thickness direction to a direction not parallel to the thickness direction, creating thickness shear mode vibration. This dimensional change improves frequency accuracy under acceleration while the integrated crystal plate structure keeps the overall device complexity manageable.
Solution Approach 2:
The vibration mode parameter is changed from conventional thickness mode to thickness shear mode. This parameter change enables the resonator to achieve better frequency accuracy under external forces while maintaining a relatively simple integrated structure.
3Object-affected harmful factors
If electrodes apply voltages with opposite polarities to induce thickness shear mode oscillation, then g-sensitivity is reduced, but the electrode configuration becomes more complex
Solution Approach 1:
The electrode configuration is segmented into a first electrode pair on the first vibration section and a second electrode pair on the second vibration section. Each pair applies voltages with opposite polarities to its respective section, enabling thickness shear mode oscillation and reduced g-sensitivity while organizing the complexity into manageable segments.
Solution Approach 2:
Different electrode pairs are disposed on different vibration sections with locally optimized polarity configurations. This local quality approach enables each section to contribute to thickness shear mode oscillation, achieving reduced g-sensitivity through distributed electrode control rather than a single complex electrode structure.
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 design significantly reduces g-sensitivity, minimizing frequency shifts caused by external forces, thereby enhancing the resonator's performance.
Implementation Method 1
The crystal plate exhibits a thickness shear mode, in which the crystal plate is driven to change shape in the oscillating direction when applied with two applied voltages
Implementation Method 2
the two surfaces of the crystal plate 11 are driven to move in unsynchronized motions (also known as out of phase movements), thereby causing the crystal plate 11, as a whole, to oscillate at the specific oscillating frequency
Data Source
AI summary
A crystal resonator includes a crystal plate and an electrode set. The crystal plate includes a first vibration section and a second vibration section arranged along an oscillating direction, and exhibits a thickness shear mode. The electrode set includes a first electrode pair disposed on the first vibration section, and a second electrode pair disposed on the second vibration section. The first electrode pair and the second electrode pair are configured to apply the applied voltages with opposite electrical polarities to the first vibration section and the second vibration section, respectively, which causes the first vibration section and the second vibration section to dynamically deform in the thickness shear mode along the oscillating direction, and do out of phase motion with respect to each other.