Planar Light Source Using Segmented Cathodes for Brightness Consistency
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Solution Overview
Problem
Field emission display devices using AC voltage for driving a planar light source experience rapid transitions between light on and off, making it difficult to maintain consistent brightness, while using DC voltage results in high power consumption.
Innovation Solution
The apparatus features a cathode connected to ground and a gate receiving an AC square wave or DC square voltages with controlled phases, allowing the emission layers on both cathodes and gates to produce electrons alternately, ensuring consistent brightness levels similar to DC-driven systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If AC voltage is used to drive the cathode plate, then power consumption is reduced, but brightness consistency deteriorates due to rapid transitions between light on and off
Solution Approach 1:
The cathode plate is divided into multiple independent emitting regions (first cathode region and second cathode region) that can be controlled separately. By alternately activating different regions, the system maintains continuous light output while using AC voltage, thus reducing power consumption while maintaining brightness consistency.
Solution Approach 2:
The patent implements continuous light emission by ensuring that while one cathode region is turning off, another is turning on. The overlapping transition periods and strategic phasing of voltage application to different regions ensure that light output remains continuous, eliminating the flicker effect and maintaining brightness consistency.
2Stability of the object's composition
If DC voltage is used to drive the cathode plate, then brightness consistency is improved, but power consumption increases
Solution Approach 1:
The patent applies periodic AC voltage with specific phase relationships to different cathode regions. By carefully controlling the phase difference and duty cycle, the system achieves continuous light emission equivalent to DC operation while benefiting from the lower power consumption of AC driving through reduced electron emission during non-active periods.
3Device complexity
If emission layers are formed only on cathodes, then device complexity is reduced, but light output uniformity deteriorates
Solution Approach 1:
The cathode plate is segmented into multiple functional regions (first cathode region with emission layer, second cathode region without emission layer) that serve different purposes. This segmentation allows for optimized electron emission control and light output uniformity while maintaining a relatively simple overall structure.
Solution Approach 2:
Different regions of the cathode plate are given different properties: the first cathode region has an emission layer for active electron emission, while the second cathode region lacks an emission layer. This local differentiation enables uniform light output across the entire plate while keeping the structure relatively simple.
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 maintains consistent brightness levels in field emission planar light sources while reducing power consumption, as the light source remains illuminated at all times, achieving the same brightness as DC-driven systems.
Implementation Method 1
the occurrence of electron emission at a tip of material in a vacuum environment due to there existing a strong electrical field
Implementation Method 2
These field-emitted electrons leaving a cathode plate accelerate toward a positively charged anode plate
Implementation Method 3
ultimately bombard with fluorescent material disposed thereon to produce light
Data Source
AI summary
An apparatus for generating a planar light source and method for driving the same is provided. The apparatus for generating a planar light source comprises an emitting layer disposed not only on a cathode electrode, but also on a gate electrode as well. Accordingly, by applying an AC voltage to the apparatus, a duty cycle of the AC voltage can reach 100% so as to enhance the brightness to the extent that the apparatus is applied a DC voltage.