Cold Cathode X-ray Tube with Electrostatic Focusing
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Solution Overview
Problem
Conventional X-ray tube focal point area movement technologies complicate the structure with high voltage thermoelectron on/off control and electromagnetic field beam control, making them complex and difficult to implement.
Innovation Solution
A cold cathode X-ray tube with a focusing structure having independently voltage-controlled focal point areas and independently on/off controllable electron beam emission areas, allowing for the movement of the focal point area through electrostatic voltage changes, simplifying the structure and enhancing focus control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional thermoelectron on/off control and electromagnetic field beam control are used to move the focal point area, then focal point area movement is achieved, but the structure of the X-ray tube becomes complex
Solution Approach 1:
The patent replaces the conventional electromagnetic field-based beam control system with a cold cathode electron emission system that uses electrostatic voltage control. This substitution eliminates the need for complex electromagnetic coils and high-voltage switching mechanisms, achieving focal point movement through simpler electrostatic focusing electrodes that deflect electron beams from multiple cold cathode elements to different focal points on the anode.
Solution Approach 2:
The patent divides the electron emission function into multiple independent cold cathode elements (e.g., first and second cold cathodes) positioned at different locations. Each cold cathode can be independently controlled to emit electron beams toward specific focal points. This segmentation allows focal point area movement by selectively activating different cathode elements or adjusting their emission characteristics, achieving versatility without requiring complex moving mechanisms.
2Ease of operation
If thermoelectrons are used as electron source with high voltage control, then electron beam emission is achieved, but the control system becomes complicated
Solution Approach 1:
The patent changes the control parameter from high-voltage switching of thermoelectron emission to lower-voltage electrostatic control of cold cathode electron emission. The cold cathode elements are controlled by applying control voltages to electrostatic focusing electrodes, which modulate the electron beam trajectories and emission timing. This parameter change from high-voltage thermal control to lower-voltage electrostatic control simplifies the control system while maintaining precise electron beam management.
Solution Approach 2:
The cold cathode elements inherently provide electron emission without requiring external heating mechanisms or complex thermal management systems. The electron emission is self-regulated through the electrostatic field control, where the focusing electrodes naturally guide and modulate the electron beams. This self-service characteristic eliminates the need for separate heating control systems and simplifies the overall control architecture.
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
Enables large movement of the focal point area with a simple structure, facilitating X-ray imaging and tomosynthesis by providing a high degree of design freedom and dynamic focus control using cold cathode and electrostatic focusing.
Implementation Method 1
an electron emission element using a cold cathode
Implementation Method 2
a focusing structure disposed between the electron emission part and a target part disposed on the anode surface... a collision area of the electron beam emitted from each of the first and second electron beam emission areas on the anode surface moves in response to a voltage applied to the focusing structure
Data Source
AI summary
The X-ray tube disclosed herein includes an electron emission part including an electron emission element using a cold cathode; an anode part having an anode surface with which an electron emitted from the electron emission part collides; and a focusing structure disposed between the electron emission part and a target part disposed on the anode surface. The focusing structure has a plurality of focal point areas that are applied with a voltage in a mutually independent manner. The electron emission part has first and second electron beam emission areas that are on/off controlled in a mutually independent manner. The X-ray tube is designed in such a way that a collision area of the electron beam emitted from each of the first and second electron beam emission areas on the anode surface moves in response to a voltage applied to the focusing structure.