Vibration Element Electrode Segmentation for Spurious Frequency Control

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Solution Overview

Problem

AT-cut quartz crystal vibrators face issues with unwanted spurious frequencies near the resonant frequency due to overlapping electrode areas, which affect their vibration characteristics and reliability in high-frequency applications.

Innovation Solution

The vibration element design includes a substrate with specific electrode configurations, such as non-overlapping excitation electrodes and narrower extraction electrode sections, ensuring a ratio of overlapping area to total excitation electrode area is less than 0.1, and optimizing electrode lengths and substrate thickness to reduce spurious frequencies and enhance vibration stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If extraction electrodes are extended from both excitation electrodes to facilitate electrical connection, then ease of operation is improved, but unwanted spurious frequencies are generated due to overlapping electrode areas

Engineering Contradiction:

Improveelectrical connectionVSAvoidspurious frequency

Core Design Contradiction:

Ease of operationVSObject-generated harmful factors

Solution Approach 1:

The extraction electrode is divided into two separate sections: one extending from the first excitation electrode and another extending from the second excitation electrode. These sections are positioned to avoid overlapping with each other, thereby eliminating the harmful overlapping area that generates spurious frequencies while maintaining electrical connectivity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different sections of the extraction electrode are designed with different spatial configurations. The first extraction electrode section is positioned separately from the second extraction electrode section, creating local variations in electrode arrangement that prevent overlapping and reduce spurious frequency generation.

Inventive Principle:

Principle #3Local quality

2Ease of operation

If electrode overlapping area is increased to improve electrical connection, then ease of operation is improved, but spurious frequencies near resonant frequency are generated

Engineering Contradiction:

Improveelectrical connectionVSAvoidvibration characteristics

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The extraction electrode is segmented into distinct sections that extend from opposite excitation electrodes. These segments are spatially separated to avoid creating overlapping areas, thus preventing the generation of spurious frequencies that would compromise vibration characteristics and reliability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The extraction electrode configuration employs asymmetric positioning where the first extraction electrode section and second extraction electrode section are arranged differently in space. This asymmetric arrangement ensures that the sections do not overlap, eliminating the harmful effect on vibration characteristics while maintaining electrical connectivity.

Inventive Principle:

Principle #4Asymmetry

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 reduces unwanted spurious frequencies, stabilizes vibration characteristics, and increases the reliability of the vibration element, oscillator, and electronic apparatuses by maintaining the resonant frequency integrity.

Implementation Method 1

AT-cut quartz crystal vibrator for exciting a thickness-shear vibration

Methodology Applied

Scientific EffectPiezoelectric effect: Piezoelectric Effect

Data Source

PatentUS9793875B2Vibration element, vibrator, oscillator, electronic apparatus, and moving object

Publication Date: 2017.10.17 SEIKO EPSON CORP

AI summary

A vibration element includes a substrate having first and second principal surfaces, a first excitation electrode on the first principal surface, a second excitation electrode on the second principal surface, and a first extraction electrode on the first principal surface, and connected to the first excitation electrode. The first extraction electrode includes a first electrode section, and a second electrode section extending from the first electrode section in a first direction and connected to the first excitation electrode. The second electrode section is narrower in a second direction than the first electrode section. When an area of the first excitation electrode is S1, and an area of an overlapping part where the second electrode section overlaps the second excitation electrode is S2, (S2/S1)≦0.1.