Double-Sided Field Emission Display With Shared Cathode
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Solution Overview
Problem
Conventional double-faced field emission display devices are bulky, costly, and have complex structures due to the need for two driving systems and independent emitting spaces, leading to high emitting voltages and inaccurate electron emission control, resulting in non-identical images on both surfaces.
Innovation Solution
A double-faced field emission display device with two parallel fluorescent screens and a single electron emission structure between them, featuring an opaque insulative substrate with alternately formed cathode plates and grid plates, allowing for symmetric interconnection and a single driving system to display the same images on both screens with low emitting voltage and accurate electron emission control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a pair of field emission display devices are combined to form a two-sided display, then simultaneous image display on both surfaces is achieved, but the device becomes bulky and costly with complex structure requiring two driving systems
Solution Approach 1:
The patent merges two separate field emission display devices into a single integrated structure by sharing the electron emission structure (cathode) between two fluorescent screens. This combining approach achieves simultaneous dual-surface display while reducing overall device complexity and eliminating the need for two separate driving systems.
Solution Approach 2:
The single electron emission structure serves multiple functions by emitting electrons toward both fluorescent screens simultaneously. The shared cathode and emitting spaces enable the device to display images on both surfaces using one driving system, achieving multi-functionality and reducing complexity.
2Length of moving object
If the distance between cathode plate and fluorescent screen is reduced to 2-30 micrometers, then device size is reduced, but emitting voltage becomes relatively high and electron emission control becomes inaccurate
Solution Approach 1:
The patent introduces a grid plate as an intermediary component between the cathode plate and fluorescent screen. This grid plate acts as a mediator that enables accurate control of electron emission while maintaining a reduced distance structure, thereby achieving both compact size and precise emission control.
Solution Approach 2:
The patent changes the electrical parameters by introducing the grid plate that can be independently controlled. By adjusting the grid plate voltage separately from the cathode voltage, the system achieves precise control over electron emission timing and intensity, solving the control accuracy problem despite reduced distances.
3Ease of manufacture
If independent emitting spaces are used for each fluorescent screen, then manufacturing is simplified, but the images displayed at the two fluorescent layers may not be identical and device complexity increases
Solution Approach 1:
The patent merges the two emitting spaces into a single shared vacuum environment. By having one common emitting space instead of two independent spaces, the system ensures identical image display on both surfaces while simplifying the evacuation process to a single operation rather than two separate procedures.
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 solution results in a simpler, smaller, and more cost-effective display device with accurate simultaneous image display on both surfaces, suitable for applications like traffic signal boards and large-scale displays, using carbon nanotube emitters to reduce voltage and enhance control.
Implementation Method 1
field emission display device comprises a fluorescent screen and an electron emission structure
Implementation Method 2
electrons are emitted from the cathode plate and bombard the fluorescent screen, whereby visible light is produced
Data Source
AI summary
A double-faced field emission display device includes two parallel fluorescent screens (10, 10′) and an electron emission structure (20) located between the fluorescent screens. Each fluorescent screen includes a transparent substrate (21, 21′) with an anode plate (12, 12′) and coplanar fluorescent layers (13, 13′) formed at an inner surface of the transparent substrate. The electron emission structure includes an opaque insulative substrate (28) with cathode plates (26, 26′), electron emitters (27, 27′) and grid plates (25, 25′) formed at each of opposite surfaces (281, 282) thereof. Symmetrically opposite pairs of same electrodes are electrically interconnected so that the fluorescent screens can simultaneous display a same image. Only a single driving system is needed to achieve the simultaneous display.