Electron Source Assembly Using Asymmetric Press-Fit Fixing

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Solution Overview

Problem

The manufacturing of minute electron sources requires skilled techniques and existing methods struggle to efficiently produce them while preventing the emitting member from coming off the holding member.

Innovation Solution

A manufacturing method involving a first member with electron emission characteristics and a second member with higher work function and lower strength, where the first member is pressed into the second member, allowing the first member to scrape and bite into the second member, forming a fixed connection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the first member (electron emission material) is pressed into the second member (holding member) with precise size matching, then the reliability of fixing is improved, but the manufacturing precision requirement becomes excessively strict and productivity decreases

Engineering Contradiction:
Improvefixing reliabilityVSAvoidsize matching precision
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

The invention applies asymmetry by making the cross-sectional shape of the columnar portion dissimilar to the cross-sectional shape of the hole. This asymmetric design allows the columnar portion to scrape and bite into the holding member during pressing, creating a reliable mechanical interlock without requiring precise size matching between the two components.

Inventive Principle:
Principle #4Asymmetry

Solution Approach 2:

The invention changes the material parameter of the holding member by selecting a material with lower strength than the electron emission material. This parameter change allows the holding member to be easily scraped and bitten by the columnar portion during pressing, ensuring reliable fixing while relaxing manufacturing precision requirements.

Inventive Principle:
Principle #35Parameter changes

2Ease of manufacture

If the hole size is made larger to accommodate the columnar portion easily, then the ease of manufacture is improved, but side emission of electrons increases

Engineering Contradiction:
Improveassembly easeVSAvoidside emission
Core Design Contradiction:
Ease of manufactureVSObject-generated harmful factors

Solution Approach 1:

The invention applies local quality by having the tubular portion cover only the side surfaces of the columnar portion while leaving the end face exposed. This localized coverage prevents side emission of electrons while maintaining ease of manufacture, as the hole can be sufficiently large for easy assembly but the electron emission is restricted to the intended end face area only.

Inventive Principle:
Principle #3Local quality

3Reliability

If the columnar portion is pressed deeply into the hole to prevent coming off, then the reliability is improved, but the manufacturing complexity increases

Engineering Contradiction:
Improvefixing reliabilityVSAvoidmanufacturing process complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The invention applies self-service by designing the columnar portion with a cross-sectional shape that automatically scrapes and bites into the holding member during the pressing process. This self-biting mechanism achieves reliable fixing without requiring complex multi-step manufacturing processes, thereby improving reliability while avoiding increased manufacturing complexity.

Inventive Principle:
Principle #25Self-service

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 method enables efficient production of minute electron sources with reduced side emission and micro-discharge occurrence, enhancing electron beam brightness and device stability.

Implementation Method 1

a portion of a side surface of the columnar portion scrapes an inner surface of the tubular portion and bites into the second member

Methodology Applied
Scientific EffectFriction: Friction

Implementation Method 2

a first member provided with a columnar portion made of a first material having an electron emission characteristic

Methodology Applied
Scientific EffectElectron emission: Thermionic Emission

Data Source

PatentEP4131328B1Electron source and method for manufacturing same, and emitter and device provided with same
Publication Date: 2025.08.13 DENKA CO LTD
  • EP4131328B1 patent drawingFigure 1
  • EP4131328B1 patent drawingFigure 2
  • EP4131328B1 patent drawingFigure 3A~3C

AI summary

A method for manufacturing an electron source according to the present disclosure includes steps of: (A) preparing a first member provided with a columnar portion made of a first material having an electron emission characteristic, (B) preparing a second member which has a higher work function and a lower strength than the first material, and in which a hole is formed extending in a direction from one end surface toward the other end surface, and (C) pushing the columnar portion into the hole in the second member, wherein the first member has a cross-sectional shape that is dissimilar to the cross-sectional shape of the hole; and in the step (C), by pressing the columnar portion into the hole, a portion of a side surface of the columnar portion scrapes the inner surface of the hole and bites into the second member, thereby fixing the columnar portion to the second member.