Carbon Nanotube Pipe Cathode for Field Emission Displays
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Solution Overview
Problem
Field emission displays using carbon nanotubes suffer from low luminous efficiency due to the planar end surface of carbon nanotube wires, which reduces the concentration of the electric field and subsequent electron emission efficiency.
Innovation Solution
The design incorporates a carbon nanotube pipe with helically oriented nanotubes forming a conical shape at the emission end, reducing the screening effect and enhancing the electric field concentration, along with a linear support for mechanical strength and a method of forming the cathode emitter using a carbon nanotube film or wire wrapped around a linear structure, which is then cut to create a hollow cylinder and snapped to form the emission peaks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If carbon nanotube wire with planar end surface is used as electron emitter, then the structure is simple and easy to manufacture, but the electric field concentration is low and electron emission efficiency is low
Solution Approach 1:
The patent transforms the planar end surface of carbon nanotube wire into a conical structure by wrapping the wire around a linear support and snapping it. This curvature transformation concentrates the electric field at the tip, significantly improving electron emission efficiency while maintaining manufacturing simplicity through the wrapping process.
Solution Approach 2:
The patent creates an asymmetric conical shape from the originally symmetric planar end surface. The conical structure with a sharp tip provides asymmetric electric field distribution that enhances field emission, resolving the contradiction between manufacturing ease and emission efficiency.
2Device complexity
If carbon nanotube wire with planar end surface is used as electron emitter, then the structure is simple, but the luminous efficiency of field emission display is low
Solution Approach 1:
By transforming the planar end surface into a conical shape through wrapping and snapping, the patent concentrates the electric field at the tip, which directly enhances electron emission and subsequently improves luminous efficiency of the field emission display.
Solution Approach 2:
The patent applies local quality change by creating a concentrated tip region with different geometric properties from the rest of the structure. This local conical shape at the emission end provides enhanced electric field concentration exactly where needed, improving luminous efficiency without complicating the overall structure.
3Ease of manufacture
If carbon nanotube wire is cut by blade, then the manufacturing process is simple, but the resulting planar end surface reduces electric field concentration
Solution Approach 1:
Instead of cutting the carbon nanotube wire to create a planar end surface, the patent wraps the wire around a linear support and snaps it to form a conical shape. This method maintains manufacturing simplicity while achieving the desired curved tip geometry for electric field concentration.
Solution Approach 2:
The patent introduces a linear support as a preliminary structure around which the carbon nanotube wire is wrapped. This preliminary action of wrapping before snapping enables the formation of the conical shape, resolving the contradiction between simple manufacturing and desired end surface geometry.
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 significantly increases the luminous efficiency of the field emission display by concentrating the electric field and improving mechanical strength, leading to enhanced electron emission and display brightness.
Implementation Method 1
Field emission displays (FEDs) are based on the emission of electrons in a vacuum. Electrons are emitted from micron-sized tips in a strong electric field
Implementation Method 2
the carbon nanotube pipe includes a first end, a second end oriented to the first end, and a main body connecting the first end and the second end. The second end forms a conical shape... enhancing the electric field concentration
Implementation Method 3
the electrons are accelerated to collide with a fluorescent material, which then emits visible light
Data Source
AI summary
A pixel tube for field emission display includes a sealed container, an anode, a phosphor, and a cathode. The sealed container has a light permeable portion. The anode is located on the light permeable portion. The phosphor layer is located on the anode. The cathode is spaced from the anode and includes a cathode emitter. The cathode emitter includes a carbon nanotube pipe. One end of the carbon nanotube pipe has a plurality of carbon nanotube peaks.