Field Emitter Alignment via Electrostatic Actuation
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Solution Overview
Problem
Field emission devices with high aspect ratio emitters are challenging to align vertically during manufacturing, leading to inclined emitter configurations that affect the focusing performance of electron beams in industrial X-ray inspection apparatuses.
Innovation Solution
The implementation of alignment electrodes surrounding the emitter's side surface, which can be individually connected to ground power or voltage, allowing for the adjustment of the emitter's position through applied voltages to align the emitter vertically, thereby ensuring the electron beam's central line passes through the gate electrode's central portion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high aspect ratio emitters are used to improve electron emission performance, then field emission capability is improved, but alignment precision deteriorates due to difficulty in vertical alignment during manufacturing
Solution Approach 1:
Alignment electrodes are introduced as intermediary components between the cathode electrode and gate electrode. These alignment electrodes generate electric fields that exert forces on the high aspect ratio emitter, enabling precise vertical alignment during operation without requiring perfect alignment during manufacturing. The alignment electrodes act as mediators that compensate for manufacturing tolerances.
Solution Approach 2:
The patent utilizes changes in electric field parameters (voltage applied to alignment electrodes) to dynamically adjust the position and orientation of the emitter. By varying the voltage parameters of the alignment electrodes, the emitter can be precisely positioned in the vertical direction, transforming a manufacturing precision problem into a controllable operational parameter problem.
2Ease of manufacture
If emitters are manufactured in an inclined state to simplify manufacturing process, then ease of manufacture is improved, but focusing performance deteriorates because the electron beam cannot be properly focused onto the target
Solution Approach 1:
The alignment electrodes are pre-positioned and configured to compensate for the known inclined manufacturing state of the emitter. By applying appropriate voltages to these pre-positioned electrodes, the system performs preliminary alignment action that corrects the inclination before the electron beam is generated, ensuring proper focusing performance despite the simplified manufacturing process.
Solution Approach 2:
The alignment electrodes serve as intermediaries that decouple the manufacturing process from the operational performance. They allow the emitter to be manufactured in a simplified inclined state while still achieving proper vertical alignment and focusing during operation, acting as a buffer between manufacturing simplicity and performance requirements.
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 solution effectively realigns the emitter and improves the focusing performance of the field emission device by ensuring the electron beam with high electron density is accurately focused onto the target, enhancing the device's operational efficiency.
Implementation Method 1
a positive voltage may be applied to at least one of the alignment electrodes, and the upper end of the emitter may be moved toward the alignment electrode to which the positive voltage is applied
Implementation Method 2
A principle of field emission is that an electron is extracted from a material to the outside when a strong electric field is applied to the emitter
Data Source
AI summary
Provided is a field emission device including a cathode electrode and an anode electrode, which are spaced apart from each other, an emitter disposed on the cathode electrode, a gate electrode disposed between the cathode electrode and the anode electrode and including a gate opening that overlaps the emitter, and a plurality of alignment electrodes disposed between the gate electrode and the cathode electrode. Here, the alignment electrodes surround a side surface of the emitter.