Electron Source Assembly With Interference-Fit Emitter Geometry
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Solution Overview
Problem
Manufacturing minute electron sources requires skilled techniques due to their small size, and existing methods struggle with defects caused by size mismatches between columnar and tubular components, leading to issues like the columnar portion not entering the hole or protruding excessively, resulting in electron emission and manufacturing inefficiencies.
Innovation Solution
A method involving the selection and pressing of columnar and tubular members with specific cross-sectional shapes and size ratios, where the columnar portion abuts the inner surface of the tubular portion, ensuring a secure fit and reducing manufacturing defects, and forming a flat surface to inhibit electron side emission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a columnar portion is pressed into a hole to fix the electron source, then the electron source can be manufactured, but size mismatch between the columnar portion and hole causes defects such as the columnar portion not entering the hole or coining off the hole
Solution Approach 1:
The patent applies preliminary action by pre-forming the columnar portion with a specific cross-sectional shape (where the circumcircle diameter is larger than the hole diameter) before the pressing operation. This preliminary shaping ensures that during pressing, the columnar portion will properly engage with the hole without causing coining defects, thereby resolving the size mismatch problem before the actual assembly occurs.
Solution Approach 2:
The patent employs asymmetry by designing the columnar portion with a non-circular cross-sectional shape (such as rectangular or elliptical) rather than a circular shape. This asymmetric design, combined with the condition that the circumcircle diameter exceeds the hole diameter, creates a controlled interference fit that prevents coining while ensuring proper insertion, thus improving manufacturing precision without significantly increasing complexity.
2Ease of manufacture
If the columnar portion is made with a cross-sectional shape that allows easy manufacturing, then manufacturing is simplified, but the portion may not securely fit into the hole or may coin off
Solution Approach 1:
The patent applies parameter changes by modifying the geometric parameters of the columnar portion, specifically setting the circumcircle diameter of its cross-section to be larger than the hole diameter. This parameter adjustment transforms the fitting relationship from a loose fit to a controlled interference fit, ensuring secure attachment while preventing coining, thus improving reliability without complicating the manufacturing process.
3Productivity
If minute electron sources are manufactured using conventional techniques, then production can proceed, but manufacturing efficiency is low due to skilled technique requirements and defect rates
Solution Approach 1:
The patent improves productivity by applying preliminary action through pre-forming the columnar portion with optimized geometric parameters before assembly. This preliminary preparation reduces the skill level required during the pressing operation and minimizes defect rates, thereby increasing manufacturing efficiency without sacrificing the high precision needed for minute electron sources.
Solution Approach 2:
The patent enhances manufacturing efficiency through parameter changes by optimizing the cross-sectional geometry of the columnar portion. By setting specific dimensional relationships (circumcircle diameter larger than hole diameter), the patent simplifies the pressing operation, reduces rework and scrap, and enables less skilled operators to achieve high-precision results, thus improving overall productivity.
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 approach enables efficient manufacturing of minute electron sources with reduced defects, effectively preventing the columnar portion from coining off and minimizing side electron emission, thereby improving the reliability and performance of electron sources in devices like electron microscopes and semiconductor inspection devices.
Implementation Method 1
by pressing the columnar portion into the hole of the second member, a portion of a side surface of the columnar portion abuts an inner surface of the hole of the second member, thereby fixing the columnar portion to the second member
Implementation Method 2
a columnar portion made of a first material having an electron emission characteristic
Data Source
AI summary
An electron source according to the present disclosure includes a columnar portion made of a first material having an electron emission characteristic; and a tubular portion that is disposed to surround the columnar portion and made of a second material having a higher work function than the first material, wherein a hole that extends in a direction from one end face toward the other end face and has a substantially circular cross-sectional shape is formed in the tubular portion, and the columnar portion has a substantially triangular or substantially quadrangular cross-sectional shape and is fixed to the tubular portion in an abutting engagement with an inner surface of the hole.