X-Ray Tube Filament Heating Circuit for Accurate AC Current Control

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Solution Overview

Problem

Existing X-ray tube systems face challenges in accurately and efficiently regulating filament current due to steep emission curves and aging-related resistance changes, necessitating complex and costly circuitry for precise AC heating current detection and frequent recalibration.

Innovation Solution

An electronic circuit that measures and regulates AC heating voltage and current directly at the filament, using a controlled variable that includes both AC heating voltage and current, allowing for precise temperature control and reduced reliance on indirect detection methods.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If AC heating current is measured indirectly using transformer primary-side current, then galvanic isolation is achieved, but measurement precision deteriorates due to steep emission curves requiring highly accurate detection

Engineering Contradiction:

Improvegalvanic isolationVSAvoidAC heating current detection accuracy

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

The patent introduces an intermediary measurement approach by measuring both the AC heating voltage and current directly at the filament, rather than relying solely on transformer primary-side current measurement. This intermediary measurement of voltage and current allows for more accurate determination of the controlled variable (heating power) while maintaining galvanic isolation through the transformer for the high voltage side.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Measurement precision

If filament learning is performed frequently to compensate for aging, then tube current accuracy is maintained, but loss of time increases due to repeated recalibrations

Engineering Contradiction:

Improvetube current accuracyVSAvoidrecalibration interval

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The patent implements a feedback mechanism by continuously measuring both AC heating voltage and current, calculating the controlled variable (heating power), and using this feedback to regulate the filament heating process. This real-time feedback reduces the need for frequent filament learning recalibrations because the system can compensate for aging effects through continuous monitoring and adjustment, thereby reducing the loss of time associated with repeated recalibrations.

Inventive Principle:

Principle #23Feedback

3Measurement precision

If AC heating current detection circuitry is made highly accurate, then regulation precision is improved, but device complexity increases due to complicated and costly circuitry

Engineering Contradiction:

ImproveAC heating current detection accuracyVSAvoiddetection circuitry complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces complex mechanical/electrical detection circuitry with a more straightforward measurement and calculation approach. Instead of using highly complex and costly detection circuitry to directly measure filament current, the system measures voltage and current on the primary side, calculates the controlled variable (heating power), and uses this to regulate the process. This substitution reduces device complexity while maintaining regulation precision.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 enhances regulation accuracy, reduces overshoots, and extends the interval between recalibrations, improving the efficiency and reliability of X-ray tube performance.

Implementation Method 1

an inverter unit (8) configured on an input side to receive a DC heating voltage (10) and to convert the DC heating voltage (10) depending on a manipulated variable (12) into an AC heating voltage (6)

Methodology Applied

Scientific EffectElectrical Energy Conversion:

Implementation Method 2

The filament is heated by an electrical current flow to such an extent that electrons are released from the metal lattice of the filament

Methodology Applied

Scientific EffectJoule Heating: Joule Heating

Implementation Method 3

in such cases galvanic isolation in the form of a transformer, also known as a filament transformer, is necessary for insulation purposes

Methodology Applied

Scientific EffectElectromagnetic Induction: Electromagnetic Induction

Data Source

PatentUS20260082473A1Electronic circuit and method of heating a filament of an x-ray tube

Publication Date: 2026.03.19 SIEMENS HEALTHINEERS AG

AI summary

An electronic circuit is configured to provide an AC heating voltage for heating a filament of an X-ray tube. The electronic circuit contains an inverter configured on the input side to receive a DC heating voltage and to convert the DC heating voltage depending on a manipulated variable into an AC heating voltage and to make available the AC heating voltage on the output side. Similarly, the electronic circuit contains a controller configured to measure the AC heating voltage and an AC heating current resulting from the AC heating voltage and depending on the AC heating voltage and the AC heating current to determine a controlled variable. The controller is configured to vary the manipulated variable depending on the controlled variable, in order to regulate the controlled variable in a regulating circuit to a specified target value.