X-Ray Tube Cathode Trench Structure for Stable Focal Spot Control

Resolve Bottlenecks,
Find Innovative Solutions
Generate Solutions

Solution Overview

Problem

Existing X-ray tubes face challenges in continuously controlling focal spot dimensions and tube current, leading to discontinuous image quality during helical scanning, which can result in inaccurate diagnoses and potential tube damage due to overcurrent issues.

Innovation Solution

An X-ray tube design featuring a rotating-anode X-ray tube with a cathode including a filament coil and an electron convergence cup with specific groove portions that allow for adjustable bias voltages to control focal spot dimensions, enabling simultaneous adjustment of focal spot length and width, thereby stabilizing focal spot control and tube current.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If two fixed focal spots are provided, then the structure is simple, but the image quality continuity is poor during helical scanning

Engineering Contradiction:
ImprovestructureVSAvoidimage quality continuity
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The patent applies the dynamics principle by making the focal spot dimensions dynamically adjustable through voltage control. The electron convergence cup's bias voltage can be varied to continuously change the focal spot size, transforming the static two-focal-spot system into a dynamic continuous adjustment system that maintains image quality continuity during helical scanning.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent applies parameter changes by varying the bias voltage applied to the electron convergence cup to control focal spot dimensions. By changing the voltage parameter, the focal spot size can be continuously adjusted between small and large dimensions, enabling smooth transitions that maintain image quality continuity without requiring multiple fixed focal spots.

Inventive Principle:
Principle #35Parameter changes

2Adaptability or versatility

If focal spot dimensions are changed by controlling multiple electrode voltages, then the focal spot can be adjusted, but the control system becomes complicated

Engineering Contradiction:
Improvefocal spot adjustment capabilityVSAvoidcontrol system
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent applies the extraction principle by isolating the electron convergence cup as a single control element for focal spot dimension adjustment. Instead of controlling multiple electrodes, the invention extracts the key function to the electron convergence cup's bias voltage, simplifying the control system while maintaining focal spot adjustment capability.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent applies multi-functionality by making the electron convergence cup serve dual purposes: it focuses the electron beam onto the target and simultaneously controls the focal spot dimensions through bias voltage adjustment. This single component performs multiple functions, eliminating the need for separate control systems for different electrodes.

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Ease of operation

If separate control systems are used for tube current and focal spot dimensions, then each can be controlled independently, but overcurrent may occur causing tube breakage

Engineering Contradiction:
Improveindependent controlVSAvoidtube safety
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The patent applies the merging principle by combining the tube current control and focal spot dimension control into a single integrated control system. The bias voltage to the electron convergence cup controls both parameters simultaneously, ensuring they remain conformant and preventing overcurrent conditions that could cause tube breakage.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent applies feedback by implementing coordinated control where the relationship between tube current and focal spot dimensions is continuously monitored and adjusted. The control system ensures that current input is appropriate for the selected focal spot size, preventing overcurrent conditions through real-time coordination.

Inventive Principle:
Principle #23Feedback

4Adaptability or versatility

If the variation of focal spot dimensions greatly differs from bias voltage changes, then focal spot can be controlled, but simultaneous adjustment of dimensions and current is difficult

Engineering Contradiction:
Improvefocal spot dimension controlVSAvoidsimultaneous adjustment
Core Design Contradiction:
Adaptability or versatilityVSEase of operation

Solution Approach 1:

The patent applies parameter changes by using the electron convergence cup's bias voltage as a unified control parameter that simultaneously affects both focal spot dimensions and tube current. By changing this single voltage parameter, both dimensions and current are adjusted together in a coordinated manner, simplifying operation.

Inventive Principle:
Principle #35Parameter changes

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 allows for simple and stable control of focal spot dimensions and tube current, ensuring continuous image quality and preventing tube damage by allowing for optimal adjustment of focal spot dimensions and current levels, enhancing diagnostic accuracy and tube longevity.

Implementation Method 1

The filament coil can emit electrons

Methodology Applied
Scientific EffectThermionic emission: Thermionic Emission

Implementation Method 2

Between the anode target and the cathode, a high tube voltage of several tens of kilovolts to hundreds of kilovolts is applied. Thus, the electron convergence cup can serve as an electron lens; that is, it can cause an electron beam traveling toward the anode target to converge

Methodology Applied
Scientific EffectElectron lens effect: Electrostatic Lens

Implementation Method 3

A focus is formed in an anode target and emits X-rays when an electron beam collide the anode target

Methodology Applied
Scientific EffectBremsstrahlung radiation: X-Ray

Data Source

PatentEP2869327B1X-ray tube
Publication Date: 2023.10.25 CANON ELECTRON TUBES & DEVICES CO LTD
  • EP2869327B1 patent drawingFigure 1
  • EP2869327B1 patent drawingFigure 2
  • EP2869327B1 patent drawingFigure 3~4

AI summary

Provided is an x-ray tube capable of easily and stably performing a focus dimension variable control and a tube current control. The x-ray tube is equipped with a cathode (10) having a filament (11) and a trench portion (16) in which the filament (11) is housed. In the x-ray tube, the trench portion (16) has: a pair of first bottom surfaces (S1) having the same plane as a plane on which the filament (11) is positioned and sandvviching the filament (11) in the width direction (db) of the trench potion (16); and second bottom surfaces (S2) sandwiching the filament (11) and the pair of first bottom surfaces (S1) in the length direction (da) of the trench portion (16) and positioned on the more opening (16a) side of the trench portion (16) than the pair of first bottom surfaces (S1).