Ionization Gauge Cartridge Structure to Suppress Electrode Deposition

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Solution Overview

Problem

Ionization gauges experience a decrease in discharge inducing performance over time due to substance deposition on the surfaces of the projecting portions, making it difficult to maintain effective discharge.

Innovation Solution

The ionization gauge incorporates a cartridge with a concave-convex structure in the through holes of the pole pieces and anode, which increases the surface area and reduces particle deposition, thereby maintaining discharge performance by preventing film formation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a smooth surface is used in the through hole, then the structure is simple and easy to manufacture, but substances are deposited on the surface making discharge difficult to induce over time

Engineering Contradiction:
Improvedischarge inducing performanceVSAvoidstructure of through hole
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The through hole is designed with projecting portions that create local convex and concave regions. The convex portions (projecting portions) have reduced surface area where substances would deposit, while the concave portions provide spaces where deposited substances accumulate without affecting the discharge inducing function. This local differentiation of surface properties maintains discharge performance over time.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The projecting portions are designed with curved surfaces rather than flat surfaces. The convex curved surfaces minimize the area where substances can deposit and adhere, while the concave regions between projecting portions provide collection spaces. The curved geometry reduces the effective surface area exposed to particle deposition compared to a flat surface.

Inventive Principle:
Principle #14Spheroidality (Curvature)

2Reliability

If the surface area of the cathode and anode is increased, then discharge inducing performance is improved, but particle deposition on the surface increases

Engineering Contradiction:
Improvedischarge inducing performanceVSAvoidparticle deposition
Core Design Contradiction:
ReliabilityVSLoss of substance

Solution Approach 1:

The surface is divided into functional zones: convex portions that actively induce discharge with minimized deposition area, and concave portions that serve as collection zones for deposited particles. This local differentiation allows the overall surface area to be increased for better discharge induction while the actual deposition-prone surfaces (convex portions) maintain relatively small area.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The concave portions between projecting portions serve as traps for deposited particles and substances. By providing dedicated collection zones, the harmful deposition effect is converted into a beneficial feature where particles are collected in controlled locations rather than uniformly covering the discharge-inducing surfaces, thereby maintaining long-term discharge performance.

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

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 concave-convex structure effectively suppresses the deposition of particles, enhancing the longevity and efficiency of the discharge inducing performance by increasing the surface area and reducing film formation on the cathode and anode surfaces.

Implementation Method 1

a gas is ionized by applying a voltage between an anode and a cathode and thus causing discharge

Methodology Applied
Scientific EffectIonization: Ionisation

Implementation Method 2

a gas is ionized by applying a voltage between an anode and a cathode and thus causing discharge

Methodology Applied
Scientific EffectDischarge: Townsend Discharge

Data Source

PatentEP3998467B1Ionization vacuum gauge and cartridge
Publication Date: 2024.01.03 CANON ANELVA CORP
  • EP3998467B1 patent drawingFigure 1
  • EP3998467B1 patent drawingFigure 2
  • EP3998467B1 patent drawingFigure 3~4

AI summary

An ionization gauge includes an anode having a rod shape, and a cathode including a cathode plate having a through hole through which the anode extends. A shape of the through hole on a section along an axial direction of the anode includes a concave portion sandwiched between two convex portions.