Quartz Resonator Notch Design for Impact Resistance
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Solution Overview
Problem
Quartz crystal resonator elements face issues with vibration leakage and stress concentration due to etching anisotropy, leading to over-etching and potential breaking when impacted, as the notch in the base is excessively etched, concentrating stress at the tip end.
Innovation Solution
The resonator element is designed with notches cut at specific angles relative to the quartz crystal axes, featuring a slope portion that changes the etching rate at the tip end, reducing stress concentration and over-etching, and is configured to form a tuning fork structure for improved impact resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a notch is formed in the base to suppress vibration leakage, then the Q value stability is improved, but the tip end of the notch becomes over-etched and stress is concentrated
Solution Approach 1:
The patent applies local quality by creating a slope portion at the tip end of the notch, making this specific region have different geometric properties (gradually decreasing width) compared to the rest of the notch. This local modification changes the stress distribution and etching behavior at the critical tip end region, resolving the contradiction between maintaining Q value stability through notch formation and preventing stress concentration that would reduce impact resistance.
Solution Approach 2:
The slope portion is designed in advance to prevent over-etching before it occurs. By pre-configuring the notch geometry with a gradual width reduction at the tip end, the patent anticipates and prevents the harmful effect of stress concentration and potential breaking, while still achieving the desired vibration leakage suppression.
2Ease of manufacture
If the notch width is maintained uniformly, then manufacturing is simpler, but stress concentrates at the tip end reducing strength
Solution Approach 1:
Instead of maintaining uniform notch width throughout, the patent introduces a slope portion at the tip end where the width gradually decreases. This local variation in geometry simplifies the overall manufacturing process while simultaneously addressing the stress concentration problem, as the sloped geometry naturally distributes stress more evenly without requiring complex multi-step fabrication.
3Reliability
If etching is performed to create the notch, then vibration leakage is suppressed, but etching anisotropy causes over-etching at the tip end
Solution Approach 1:
The slope portion creates a local geometric feature at the notch tip end that interacts differently with the etching process. The gradually decreasing width configuration compensates for etching anisotropy effects, ensuring that the final notch dimensions match the design specifications more accurately while still achieving effective vibration leakage suppression.
Solution Approach 2:
The pre-configured slope portion acts as a countermeasure to the harmful effect of over-etching. By designing the notch with this geometric feature before etching, the patent anticipates the anisotropy-induced over-etching and compensates for it in the design, thereby maintaining manufacturing precision.
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 configuration effectively suppresses vibration leakage and over-etching, enhancing the strength and impact resistance of the resonator element by distributing stress more evenly and maintaining a balanced vibration.
Implementation Method 1
A resonator element made from a quartz crystal has etching anisotropy: that is, the etching rate differs depending on the direction with respect to the quartz crystal axes of the quartz crystal.
Implementation Method 2
since a notch is formed in the base, a leakage of vibration from the resonating arm to the base decreases
Implementation Method 3
the concentration of stress in the tip end of the notch is suppressed in the resonator element
Data Source
AI summary
A resonator element capable of improving impact resistance is provided. A quartz crystal resonator element is a resonator element formed by etching a Z plate which is cut at predetermined angles with respect to the crystal axes of a quartz crystal. The quartz crystal resonator element includes a base, a pair of resonating arms extending from the base in the Y-axis direction, and a positive X-axis notch and a negative X-axis notch formed by notching the base in the X-axis direction. The positive X-axis notch is formed by notching the base from the negative side of the X axis towards the positive side so that the width of the positive X-axis notch increases as it approaches the outer circumference.