Atomic Cell Coating for Frequency Stability

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Solution Overview

Problem

Existing atomic cells with uncoated through-holes for sealing suffer from instability in alkali metal behavior, leading to deteriorated frequency stability, especially as they are scaled down, due to increased ratios of opening area to inner wall surface area.

Innovation Solution

The implementation of a coating film on the inner wall surface and a coating member with similar characteristics at the through-hole opening, along with a sealing material and optional cushioning material, to stabilize metal atom behavior and improve frequency stability by preventing reaction and diffusion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If the atomic cell is scaled down to reduce size, then the device becomes more compact, but the ratio of opening area to inner wall surface area increases causing instability in metal atom behavior

Engineering Contradiction:

Improvesize of atomic cellVSAvoidfrequency stability

Core Design Contradiction:

Volume of moving objectVSReliability

Solution Approach 1:

The invention applies coating not only to the inner wall surface but specifically extends it to the opening of the through-hole where metal atoms enter. This localized coating at the critical interface stabilizes metal atom behavior without requiring a larger cell volume, thus resolving the contradiction between miniaturization and frequency stability.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The coating is applied in advance to the opening surface before metal atoms are introduced into the cell. This preliminary preparation prevents unwanted reactions and diffusion at the entry point, ensuring stable atom behavior from the moment of introduction even in miniaturized cells.

Inventive Principle:

Principle #10Preliminary action

2Reliability

If coating is applied to the inner wall surface to prevent reaction and diffusion, then metal atom behavior is stabilized, but the opening of the through-hole remains uncoated causing instability

Engineering Contradiction:

Improvemetal atom behavior stabilityVSAvoidcoating application complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The invention merges the coating of the inner wall surface with the coating of the through-hole opening into a single continuous coating layer. This unified approach ensures consistent material properties across the entire internal surface without requiring separate coating processes, thus avoiding increased device complexity while maintaining atom behavior stability.

Inventive Principle:

Principle #5Merging (Combining)

3Reliability

If a coating member is arranged in the through-hole to provide coated surface at opening, then metal atom behavior is stabilized, but the sealing process becomes more complex

Engineering Contradiction:

Improvefrequency stabilityVSAvoidsealing process difficulty

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The invention changes the physical state of the sealing material from solid to liquid during the sealing process, allowing it to flow and conform to the coating member and through-hole geometry. After sealing, the material solidifies to provide a hermetic seal. This parameter change simplifies the sealing process despite the presence of the coating member.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The sealing material acts as an intermediary that bonds the coating member to the cell structure while maintaining the integrity of the coating surface. This intermediary material facilitates the sealing process without requiring direct contact between the coating member and the sealing structure, thus simplifying manufacturing.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 enhances the stability of metal atoms and frequency stability in atomic cells, allowing for smaller, more reliable atomic oscillators and related devices.

Implementation Method 1

coating for preventing reaction or diffusion of the alkali metal to the glass forming an inner wall surface is applied to the inner wall surface

Methodology Applied

Scientific EffectPhysical barrier:

Implementation Method 2

coating for preventing reaction or diffusion of the alkali metal to the glass forming an inner wall surface is applied to the inner wall surface

Methodology Applied

Scientific EffectChemical inertness:

Implementation Method 3

a sealing material arranged further on the outer side than the coating member in the through-hole and configured to seal the internal space

Methodology Applied

Scientific EffectPhysical containment: Physical Containment

Data Source

PatentUS9673830B2Atomic cell, manufacturing method for atomic cell, quantum interference device, atomic oscillator, electronic apparatus, and moving object

Publication Date: 2017.06.06 SEIKO EPSON CORP

AI summary

An atomic cell includes an internal space in which alkali metals are encapsulated, a coating film formed on the wall surface of the internal space, holes that allow the internal space and the outside to communicate with each other, and coating members having surfaces that face the internal space along openings of the holes on the internal space side and formed of a coating material having a characteristic same as or similar to a characteristic of the coating film.