Field Emission Cathode with Anchored Carbon Nanotubes
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Solution Overview
Problem
Carbon nanotube-based field emission cathode devices in FEDs have a short lifespan due to carbon nanotubes being pulled out by strong electric field forces, as they are not securely attached to the cathode.
Innovation Solution
The field emission cathode device incorporates linear carbon nanotube structures with a fixing portion secured between the insulative substrate and cathode electrodes, preventing the nanotubes from being dislodged by electric field forces, and includes a conductive layer to manage electron emission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If carbon nanotubes are fabricated on the cathode by chemical vapor deposition (CVD), then the field emission cathode device can be manufactured, but the carbon nanotubes are not secured on the cathode and tend to be pulled out by strong electric field forces causing short device life
Solution Approach 1:
The patent applies preliminary action by pre-forming protrusions on the cathode surface before depositing carbon nanotubes. These protrusions serve as anchoring structures that secure the nanotubes in place before they are subjected to strong electric field forces during operation, preventing their dislodgement and extending device lifespan.
Solution Approach 2:
The patent introduces an intermediary structure (protrusions) between the cathode and the carbon nanotubes. These protrusions act as mechanical anchors that physically secure the nanotubes to the cathode surface, providing a stable attachment mechanism that prevents nanotube dislodgement under electric field stress.
2Device complexity
If carbon nanotubes are directly mounted on the cathode without securing structures, then the device structure is simple, but the nanotubes are easily dislodged by electric field forces reducing device reliability
Solution Approach 1:
The cathode surface is pre-formed with protrusions before nanotube deposition. This preliminary structural preparation creates secure attachment points for the nanotubes without requiring complex additional components, maintaining relative structural simplicity while significantly improving attachment stability.
Solution Approach 2:
The patent applies local quality by creating protrusions at specific locations on the cathode surface where nanotubes will be deposited. These localized structural features provide enhanced attachment capability precisely where needed, rather than uniformly complicating the entire cathode structure.
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 design secures the electron emission units, enhancing the lifespan of the field emission cathode device and maintaining reliable electron emission performance.
Implementation Method 1
carbon nanotube-based FEDs have attracted much attention in recent years... A field emission cathode device based on carbon nanotubes for triode FEDs... the carbon nanotubes tend to be pulled out from the cathode by a strong electric field force causing the field emission cathode device to have a short life
Data Source
AI summary
A field emission cathode device includes an insulative substrate, a number of cathode electrodes, and a number of liner electron emission units. The insulative substrate has a top surface and a bottom surface. The insulative substrate defines a number of openings. The cathode electrodes are located on the bottom surface. Each of the linear electron emission units has a first portion secured between the insulative substrate and one corresponding cathode electrode and a second portion received in one corresponding opening.