Quartz Crystal Resonator Coupling Structure for Compact Vibration Control
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Solution Overview
Problem
Conventional quartz crystal resonators face challenges in reducing size while maintaining vibration characteristics due to anisotropic etching of quartz crystals, leading to increased outer size and decreased vibration area.
Innovation Solution
A quartz crystal resonator design featuring a body portion with specific excitation electrodes and coupling members made of quartz crystal, where the coupling members have thinner sections than the body portion, allowing for reduced size without compromising vibration confinement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If the size of the piezoelectric chip is reduced, then the outer size decreases, but the area of the vibration portion decreases and vibration characteristics deteriorate
Solution Approach 1:
The patent applies local quality by creating a through portion only at specific locations (opposite the coupling portion) rather than along the entire periphery. This localized approach allows the vibration portion to maintain its area for good vibration characteristics while the overall chip size is reduced, as the frame can be positioned closer without compromising vibration performance.
2Area of moving object
If providing an appropriate area to the vibration portion is prioritized, then vibration characteristics are maintained, but the outer size of the piezoelectric chip increases
Solution Approach 1:
The patent extracts the through portion from being a continuous peripheral feature and places it only at specific locations opposite the coupling portion. This extraction allows the frame to be positioned closer to the vibration portion, reducing the outer size while maintaining the vibration portion area, as the through portion is only where structurally necessary.
3Reliability
If a through portion is formed between the frame and the periphery of the vibration portion, then coupling is achieved, but a comparatively large distance must be provided between the vibration portion and the frame
Solution Approach 1:
The patent uses the coupling portion as an intermediary element that mediates between the frame and the vibration portion. By positioning the through portion opposite this coupling portion rather than along the entire periphery, the frame can be positioned closer to the vibration portion while still achieving reliable coupling through the intermediary coupling 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 enables a compact quartz crystal resonator unit with preserved vibration characteristics, improved strength against external impacts, and reduced probability of extension electrode breakage.
Implementation Method 1
a piezoelectric substrate having a piezoelectric chip
Implementation Method 2
Because a quartz crystal has an anisotropic crystal structure, the dissolution rate of wet etching differs in accordance with crystal orientation
Data Source
AI summary
A method of forming a quartz crystal resonator is provided with the resonator including a body portion with first and second main surfaces facing each other and, in plan view having a pair of long sides extending in a first direction and a pair of short sides extending in a second intersecting direction. Moreover, first and second excitation electrodes are formed on the respective main surfaces; a frame surrounds the body portion at both ends and is separated from the both ends; and first and second coupling portions extend from the short sides and with widths of the short sides. At least one of the first and second coupling portions is formed with a thickness in a third direction is smaller than a thickness in the third direction of a region of the body portion where the first excitation electrode and the second excitation electrode face each other.