Gold-Layer Crystal Electrodes for Stable Drive Level Dependency
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Solution Overview
Problem
Existing crystal elements exhibit drive level dependency (DLD) where resonance frequency increases with excitation level, leading to instability and spurious oscillations, which are not effectively addressed by previous electrode structure and shape optimizations.
Innovation Solution
A crystal element with a conductive gold layer of 90% or more on both surfaces of a crystal piece, including a base layer between the conductive layer and the crystal piece, with a specific thickness range and resonance frequency product value to achieve a mixed positive and negative DLD characteristic, stabilizing resonance frequency across varying excitation levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional electrode structures are used, then manufacturing is simpler, but drive level dependency causes frequency instability and spurious oscillations
Solution Approach 1:
The electrode is divided into multiple functional layers: a base layer (first electrode layer) positioned directly on the crystal piece, and a conductive layer (second electrode layer) positioned on the base layer. This segmentation allows the base layer to provide mechanical support and adhesion while the conductive layer optimizes electrical properties, thereby reducing drive level dependency and improving frequency stability without excessive complexity.
Solution Approach 2:
The electrode uses a composite structure combining different materials in the base layer and conductive layer. The base layer may use materials with specific mechanical and adhesive properties, while the conductive layer uses materials optimized for electrical conductivity. This composite approach enables simultaneous optimization of mechanical support and electrical performance, reducing DLD characteristic while maintaining manageable device complexity.
2Reliability
If electrode thickness is increased to reduce impedance, then electrical characteristics improve, but drive level dependency increases causing frequency drift
Solution Approach 1:
The electrode thickness is segmented into a base layer and a conductive layer with different thickness optimizations. The base layer provides sufficient thickness for mechanical strength and adhesion, while the conductive layer thickness is optimized for electrical conductivity. This segmentation allows achieving low impedance without excessive total thickness that would worsen DLD, thereby maintaining frequency control precision while improving electrical characteristics.
Solution Approach 2:
The electrode structure parameters (thickness, material composition of base layer and conductive layer) are optimized to achieve a balance between impedance reduction and DLD suppression. By carefully controlling the thickness and material properties of each layer, the patent achieves low crystal impedance while maintaining frequency stability across drive levels, resolving the contradiction between electrical performance and frequency precision.
3Reliability
If gold content in conductive layer is increased to 90% or more, then electrical conductivity improves and crystal impedance decreases, but manufacturing cost increases
Solution Approach 1:
The gold content in the conductive layer is optimized to 90% or more by mass ratio, providing excellent electrical conductivity and low crystal impedance. The base layer compensates for the high material cost by providing structural support, allowing the expensive gold to be used only where electrical performance is critical, thereby achieving high conductivity while controlling overall material quantity and cost.
Solution Approach 2:
The composite electrode structure allows concentrated use of expensive gold material only in the conductive layer where electrical performance is needed, while the base layer uses more economical materials for mechanical support. This strategic material distribution achieves high electrical conductivity with controlled gold quantity, balancing performance requirements with material cost considerations.
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 solution stabilizes resonance frequency and reduces crystal impedance, ensuring efficient vibration and frequency stability across a wide range of excitation levels, suppressing unwanted frequency changes and maintaining optimal electrical characteristics.
Implementation Method 1
each of the electrodes is positioned on a corresponding one of both surfaces of the crystal piece and includes a conductive layer having a gold content of 90% or more in mass ratio
Implementation Method 2
a known crystal element which obtains a signal by causing a crystal piece to resonate at a given frequency
Implementation Method 3
a crystal element which obtains a signal by causing a crystal piece to resonate at a given frequency
Data Source
AI summary
Provided are a crystal element and a crystal device that have an improved DLD characteristic. The crystal element includes a crystal piece and a pair of electrodes. Each of the electrodes is positioned on a corresponding one of both surfaces of the crystal piece and includes a conductive layer having a gold content of 90% or more in mass ratio. The crystal element has the DLD characteristic in which a portion in a positive direction (+) and a portion in an opposite direction (−) are mixed.