X-ray tube current control with constant loop gain
First Claim
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1. In a current control system for an x-ray tube having a filament driver which supplies current to the x-ray tube filament in response to a preheat command signal, the improvement comprising:
- means for producing a tube current feedback signal which indicates the amount of current flowing between the filament and the anode of the x-ray tube;
means for producing a command signal which is proportional to the reciprocal of a tube current command;
multiplying means for multiplying the tube current feedback signal by the command signal to produce a tube current error signal;
subtraction means for subtracting the tube current error signal from a reference signal to produce a corrected tube current error signal;
summing means for combining the preheat command signal with the corrected tube current error signal to produce a filament command signal to control the tube filament temperature and cause the tube current to attain a value indicated by the tube current command; and
means for supplying said filament command signal to said filament drive.
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Abstract
The tube current in an X-ray tube is controlled by a closed loop control circuit in which a tube current feedback signal is used to control X-ray tube filament current. The gain of the feedback loop is maintained substantially constant over a wide range of tube currents by inserting a signal proportional to the reciprocal of the tube current command.
32 Citations
3 Claims
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1. In a current control system for an x-ray tube having a filament driver which supplies current to the x-ray tube filament in response to a preheat command signal, the improvement comprising:
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means for producing a tube current feedback signal which indicates the amount of current flowing between the filament and the anode of the x-ray tube; means for producing a command signal which is proportional to the reciprocal of a tube current command; multiplying means for multiplying the tube current feedback signal by the command signal to produce a tube current error signal; subtraction means for subtracting the tube current error signal from a reference signal to produce a corrected tube current error signal; summing means for combining the preheat command signal with the corrected tube current error signal to produce a filament command signal to control the tube filament temperature and cause the tube current to attain a value indicated by the tube current command; and means for supplying said filament command signal to said filament drive. - View Dependent Claims (2, 3)
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Specification