Field Emission Cathode Ion Absorption for Lifetime Extension
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Solution Overview
Problem
Field emission lighting devices face ion bombardment due to unwanted ions generated from outgassing, which reduces their luminance and lifetime, and existing solutions like gate electrodes increase complexity and cost while potentially blocking light emission.
Innovation Solution
A field emission cathode with both electron emitting and ion absorbing parcels, where the ion absorbing parcel is electrically connected to the electron emitting parcel and positioned to absorb positive ions, maintaining a negative potential relative to the anode, thereby preventing ion bombardment on the electron emitting parcel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a gate electrode or ion collector is added to remove ions, then ion bombardment is reduced, but device complexity and cost increase
Solution Approach 1:
The patent combines the ion absorbing function with the electron emitting cathode structure by integrating ion absorbing parcels alongside electron emitting parcels on the same cathode substrate. This merging eliminates the need for separate gate electrodes or ion collectors, thereby reducing device complexity while still effectively absorbing positive ions and preventing ion bombardment damage to the electron emitting surfaces.
Solution Approach 2:
The cathode structure is designed to perform multiple functions simultaneously: electron emission for light generation and positive ion absorption for protecting the emission surfaces. By making the cathode multi-functional, the patent avoids adding extra components like separate ion collectors, thus reducing overall device complexity while addressing the ion bombardment problem.
2Object-affected harmful factors
If a gate electrode is added to collect ions, then ion bombardment is reduced, but light emission may be blocked
Solution Approach 1:
The cathode is segmented into distinct electron emitting parcels and ion absorbing parcels. The ion absorbing parcels are positioned to absorb positive ions before they can bombard the electron emitting parcels, while the segmentation allows electrons to be emitted from the emitting parcels and travel through the vacuum to the anode without being blocked by the ion absorbing parcels, thus protecting both light emission and ion absorption functions.
3Reliability
If additional ion removal components are added, then vacuum integrity is maintained, but manufacturing complexity increases
Solution Approach 1:
The ion absorbing parcels are integrated directly into the cathode structure during the same manufacturing process as the electron emitting parcels. This merging approach allows both functional elements to be fabricated simultaneously on a single substrate using similar techniques, eliminating the need for separate assembly steps or additional components, thereby maintaining vacuum integrity while simplifying the manufacturing process.
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 enhances the vacuum integrity and luminance of field emission lights by preferentially absorbing positive ions, reducing the need for additional power supplies and complex ion collectors, thus extending the device's lifetime and simplifying the manufacturing process.
Implementation Method 1
the ion absorbing parcel is electrically connected to the electron emitting parcel and positioned to absorb positive ions, maintaining a negative potential relative to the anode
Implementation Method 2
By applying an electric voltage through power supply 95 to the field emission light 90, an electric field is established. An electron beam emitted by the field emission cathode element 93
Data Source
AI summary
A field emission cathode comprises at least one electron emitting parcel, and at least one ion absorbing parcel each being electrically connected with each of the at least one electron emitting parcel. The electron emitting parcel includes a first substrate and a nano emission component disposed on the first substrate for emitting electrons in an electric field. The ion absorbing parcel is constituted by a second substrate, in which the electric conductivity of the first substrate is less than that of the second substrate. A field emission light comprises the said field emission cathode, a field emission anode and a power supply. Thus the positive ions in an electric field can be absorbed by ion absorbing parcels to suppress an ion bombardment in the electric field. The efficiency of the electric field of the field emission is then maintained, and the lifetime of the field emission light is enhanced.