Field Emission Display Pixel Element With Projecting CNT String
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Solution Overview
Problem
Field emission displays (FEDs) face challenges with low luminous efficiency due to the shield effect caused by adjacent carbon nanotubes (CNTs) and difficulties in manufacturing single CNTs for effective electron emission.
Innovation Solution
A pixel element design incorporating a sealed container with a CNT string where some bundles project over others, forming a tooth-shaped emission structure, reducing the shield effect and improving luminous efficiency, and using a CNT string as the electron emitter, which is easier to fabricate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If single carbon nanotubes are used as electron emitters, then field emission capability is improved, but manufacturing controllability deteriorates
Solution Approach 1:
The patent combines multiple carbon nanotubes into a bundled structure where they grow collectively from a common base. This merging approach maintains the superior field emission properties of individual nanotubes while enabling batch manufacturing through controlled chemical vapor deposition processes, thus resolving the contradiction between emission capability and manufacturability.
Solution Approach 2:
The patent controls the growth parameters (temperature, pressure, catalyst composition, gas flow rates) during chemical vapor deposition to achieve consistent nanotube bundle formation. By optimizing these parameters, the manufacturing process achieves good controllability while producing bundles with the desired field emission characteristics.
2Illumination intensity
If carbon nanotubes are arranged densely, then emission intensity is improved, but shield effect increases reducing luminous efficiency
Solution Approach 1:
The patent creates an asymmetric spatial arrangement where nanotube bundles are positioned at optimized intervals and orientations. This asymmetric distribution ensures sufficient spacing between bundles to minimize electromagnetic shielding while maintaining high emission intensity from each bundle, thereby improving luminous efficiency.
Solution Approach 2:
The patent transitions from two-dimensional planar arrangements to three-dimensional spatial distribution of nanotube bundles. By utilizing vertical positioning and angular orientation in addition to horizontal spacing, the design achieves high emission intensity while maintaining adequate separation to reduce shield effects between adjacent bundles.
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 design enhances luminous efficiency and simplifies manufacturing by utilizing a CNT string with a tooth-shaped emission structure, reducing the shield effect and improving field emission efficiency while maintaining ease of fabrication.
Implementation Method 1
Electrons are emitted from micron-sized tips in a strong electric field
Implementation Method 2
the electrons are accelerated and bombard a fluorescent material, and then the fluorescent material emits visible light
Data Source
AI summary
A pixel element for field emission display includes a sealed container having a light permeable portion, an anode, a cathode, a phosphor layer formed on an end surface of the anode, and a CNT string electrically connected to and in contact with the cathode with an emission portion of the CNT string suspending. The phosphor layer is opposite to the light permeable portion, and the emission portion is corresponding to the phosphor layer. Some of CNT bundles in the CNT string are taller than and project over the adjacent CNT bundles, and each of projecting CNT bundles functions as an electron emitter. The anode, the cathode, the phosphor layer and the CNT string are enclosed in the sealed container. The luminance of the pixel element is enhanced at a relatively low voltage.