X-Ray Tube Filament Heating Circuit for Precise AC Current Control
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Solution Overview
Problem
Existing X-ray tube systems face challenges in accurately and efficiently regulating tube current due to measurement complexities and aging-related tolerances, necessitating frequent filament learning processes.
Innovation Solution
An electronic circuit that controls the filament heating using a control variable based on heating alternating current and voltage, allowing direct measurement and regulation of AC heating parameters, including galvanic isolation and transformer-based voltage amplification, to achieve precise filament temperature control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If galvanic isolation using a transformer is implemented to insulate the filament circuit from high voltage, then safety and electrical isolation are improved, but measurement precision deteriorates because the heater current can only be measured indirectly on the primary side with complex evaluation electronics
Solution Approach 1:
The patent introduces an intermediary measurement approach by measuring the primary side current of the transformer (heater current) and using it as the control variable. Instead of directly measuring the difficult-to-access filament current on the high voltage side, the system uses the easily measurable primary current combined with the known transformer ratio to infer and control the filament current, thus resolving the measurement precision issue while maintaining galvanic isolation
Solution Approach 2:
The patent implements a feedback control mechanism where the measured primary side current is continuously monitored and used to adjust the heater alternating voltage. The control arrangement regulates the inverter unit based on the measured heater current to maintain the desired filament temperature, creating a closed-loop system that compensates for measurement tolerances and aging effects
2Measurement precision
If the emission curve with large gradient is used for tube current regulation, then tube current control sensitivity is improved, but device complexity worsens due to the need for very precise heater current measurement and complex evaluation electronics
Solution Approach 1:
The patent uses the transformer primary current as an intermediary variable that is easier to measure with standard electronics. By controlling this intermediary current through the feedback loop, the system achieves precise tube current regulation without requiring complex high-voltage measurement electronics, thus reducing device complexity while maintaining control sensitivity
Solution Approach 2:
The patent replaces complex high-voltage measurement systems with simpler low-voltage measurement electronics on the primary side of the transformer. By substituting the difficult high-voltage current measurement with an equivalent low-voltage measurement, the system achieves the same control precision with significantly reduced electronic complexity
3Measurement precision
If filament learning is performed frequently to compensate for aging and tolerance effects, then tube current accuracy is improved, but productivity deteriorates due to repeated test scans and calibration time
Solution Approach 1:
The patent implements continuous feedback control that automatically compensates for filament aging and resistance changes. The control arrangement continuously monitors the heater current and adjusts the heater voltage in real-time to maintain accurate tube current, eliminating the need for frequent manual filament learning and calibration procedures
Solution Approach 2:
The system performs self-adjustment through the feedback loop, automatically compensating for aging effects without requiring external calibration interventions. The control arrangement continuously optimizes the heater voltage based on measured heater current, enabling the system to maintain accuracy autonomously over time
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 enables faster and more accurate regulation of tube current, reduces the need for frequent filament learning, and enhances control precision, thereby improving X-ray image quality and reducing exposure time.
Implementation Method 1
an inverter unit (8) configured to convert a DC heating voltage (10) into an AC heating voltage (6)
Implementation Method 2
a transformer (13) configured to transform the AC heating voltage (6) into a filament voltage (18)
Implementation Method 3
The filament is heated by an electric current to such an extent that electrons are released from the filament's metal lattice
Implementation Method 4
The filament is heated by an electric current to such an extent that electrons are released from the filament's metal lattice
Data Source
Figure 1
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Figure 3
AI summary
Electronic circuit (20) for providing an alternating heating voltage (6) for heating a filament (3) of an X-ray tube (15). The electronic circuit (20) includes an inverter unit (8) configured to receive a direct heating voltage (10) at the input and to convert the direct heating voltage (10) into an alternating heating voltage (6) depending on a control variable (12) and to provide the alternating heating voltage (6) at the output. The electronic circuit (20) also includes a control arrangement (11) configured to measure the alternating heating voltage (6) and a heating alternating current (7) resulting from the alternating heating voltage (6) and to determine a controlled variable depending on the alternating heating voltage (6) and the heating alternating current (7). The control arrangement (11) is configured to change the control variable (12) depending on the controlled variable in order to regulate the controlled variable to a predetermined setpoint (14) in a control loop.