X-ray tube filament current closed-loop control circuit and X-ray machine
By designing the closed-loop control circuit of the X-ray tube filament current, the filament current is adjusted by using the tube current error feedback, the problem of inconsistent tube current in the use of the X-ray tube is solved, and precise dose control is achieved without calibration, improving the convenience of use and dose control accuracy.
Patent Information
- Application Number
- CN202420829942.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-04-19
- Publication Date
- 2024-12-20
- Estimated Expiration
- 2034-04-19
AI Technical Summary
During the use of existing X-ray machines, due to the filament temperature characteristics and aging of the X-ray tube, the tube current is inconsistent, resulting in large errors in the tube current after calibration, which affects the control of X-ray dose, and requires cumbersome calibration every once in a while. The process affects the convenience of use.
Design a closed-loop control circuit for filament current in X-ray tube. By collecting the error feedback between the tube current and the filament current, the filament current is automatically adjusted, so that the tube current is indirectly involved in the control of the filament current, avoiding the calibration of the X-ray tube process.
The precise control of X-ray dose without calibration is achieved, the convenience of X-ray tubes and the accuracy of dose control are improved, and the impact of temperature changes and aging on dose control is reduced.
Smart Images
Figure CN222216013U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of X-ray machines, in particular to an X-ray tube filament current closed-loop control circuit and an X-ray machine. Background Art
[0002] There is a certain mapping relationship between the filament current and the tube current of the X-ray tube. Before the X-ray machine leaves the factory, the X-ray tube needs to be calibrated, that is, the filament current of the X-ray tube is gradually increased from a small value, and the exposure is performed, and the feedback tube current value is compared to see if it is a breakpoint value, so as to obtain the mapping relationship between the filament current and the tube current of the X-ray tube, and store it in the storage medium for use in the subsequent control process. However, in actual use, due to the temperature characteristics of the filament of the X-ray tube, when the interval between the previous and subsequent exposures is not large, the consistency of the tube current is not good. As the exposure progresses, the tube current will gradually become lower, resulting in a large error in the calibrated tube current, which affects the control of the X-ray dose. And as the X-ray tube is used, the tube of the X-ray tube will age, and the actual X-ray dose will also slowly decrease. Therefore, the X-ray tube needs to be recalibrated every once in a while, and each calibration generally takes more than 20-30 minutes. The calibration process is relatively cumbersome and inconvenient to use. For this reason, it is necessary to design a new X-ray tube filament current control circuit that can ensure the accuracy of X-ray dose control without calibration. Utility Model Content
[0003] In order to overcome the shortcomings of the prior art, the purpose of the utility model is to provide an X-ray tube filament current closed-loop control circuit, which collects the tube current of the X-ray tube and feeds back the error between the tube current and the tube current reference to the filament current control circuit, so that the tube current feedback is indirectly involved in the closed-loop control of the filament current, thereby achieving accurate control of the X-ray dose without calibrating the X-ray tube.
[0004] In order to solve the above problems, the technical solution adopted by the utility model is as follows: an X-ray tube filament current closed-loop control circuit, comprising: a controller; a filament current control circuit, used to drive the cathode filament of the X-ray tube under the control of the controller; a tube current sampling circuit, whose input end is connected to the anode of the X-ray tube and is used to collect the tube current of the X-ray tube; a filament current sampling circuit, whose input end is connected to the output end of the filament current control circuit and is used to collect the filament current output to the cathode filament of the X-ray tube; a tube current closed-loop circuit, whose two input ends are respectively connected to the controller and the output end of the tube current sampling circuit, and receive the tube current reference signal output by the controller and the tube current reference signal output by the controller. The filament current sampling circuit outputs a tube current sampling signal, and the output end is connected to the control end of the filament current control circuit, and is used to feed back the error between the tube current sampling signal and the tube current reference signal to the control end of the filament current control circuit; a filament current closed-loop circuit, the two input ends of which are respectively connected to the controller and the output end of the filament current sampling circuit, receive the filament current reference signal output by the controller and the filament current sampling signal output by the filament current sampling circuit, and the output end is connected to the control end of the filament current control circuit, and is used to feed back the error between the filament current sampling signal and the filament current reference signal to the control end of the filament current control circuit.
[0005] Compared with the prior art, the beneficial effect of the utility model is that the tube current closed-loop circuit and the filament current closed-loop circuit respectively feed back the error between the tube current and the tube current reference and the error between the filament current and the filament current to the control end of the filament current control circuit, and the filament current control end adjusts the power output to the cathode filament according to the feedback signal with a larger error, so that the tube current feedback indirectly participates in the control of the filament of the X-ray tube. Even if the X-ray tube is affected by temperature characteristics or aging, causing the tube current to drop, the error between the tube current and the tube current reference will be larger, so that the filament current control circuit will adjust the current output to the X-ray tube filament according to the error between the tube current and the tube current reference, so that the tube current of the X-ray tube reaches the tube current reference, so that the X-ray dose emitted by the X-ray tube meets the given tube current reference. The X-ray tube filament current closed-loop control circuit can achieve accurate control of the X-ray dose without calibrating the X-ray tube.
[0006] The above-mentioned X-ray tube filament current closed-loop control circuit, the tube current closed-loop circuit includes a first operational amplifier, the inverting input terminal of the first operational amplifier is connected to the controller, the non-inverting input terminal of the first operational amplifier is connected to the output terminal of the tube current sampling circuit, and the output terminal of the first operational amplifier is connected to the control terminal of the filament current control circuit.
[0007] The above-mentioned X-ray tube filament current closed-loop control circuit, the tube current closed-loop circuit also includes a tube current loop compensation circuit, the tube current loop compensation circuit includes a compensation resistor and a capacitor, the inverting input end of the first operational amplifier is connected to its output end through the first tube current compensation resistor and the tube current compensation capacitor, and the two ends of the series structure formed by the first tube current compensation resistor and the tube current compensation capacitor are connected in series in parallel by the second tube current compensation resistor.
[0008] The above-mentioned X-ray tube filament current closed-loop control circuit, the filament current closed-loop circuit includes a second operational amplifier, the inverting input terminal of the second operational amplifier is connected to the controller, the non-inverting input terminal of the second operational amplifier is connected to the output terminal of the filament current sampling circuit, and the output terminal of the second operational amplifier is connected to the control terminal of the filament current control circuit.
[0009] The above-mentioned X-ray tube filament current closed-loop control circuit, the filament current closed-loop circuit also includes a filament current loop compensation circuit, the filament current loop compensation circuit includes a compensation resistor and a capacitor, the inverting input end of the second operational amplifier is connected to its output end through the filament current compensation capacitor, and the two ends of the filament current compensation capacitor are connected in parallel with a filament current compensation resistor.
[0010] The above-mentioned X-ray tube filament current closed-loop control circuit, the filament current control circuit includes a PWM controller and an inverter circuit, the output ends of the tube current closed-loop circuit and the filament current closed-loop circuit are both connected to the feedback end of the PWM controller, the output end of the PWM controller is connected to the gates of the two inverter tubes of the inverter circuit, and the input end of the filament current sampling circuit is connected to the connection node of the two inverter tubes.
[0011] In the above X-ray tube filament current closed-loop control circuit, the dead zone control pin of the PWM controller is connected to the controller to receive the mode switching signal output by the controller.
[0012] In the above X-ray tube filament current closed-loop control circuit, the PWM controller adopts a TL594 chip or a TL494 chip.
[0013] In the above X-ray tube filament current closed-loop control circuit, the output end of the filament current sampling circuit is connected to the controller through a buffer.
[0014] An X-ray machine comprises the above-mentioned X-ray tube filament current closed-loop control circuit.
[0015] The utility model is further described in detail below in conjunction with the accompanying drawings and specific implementation methods. BRIEF DESCRIPTION OF THE DRAWINGS
[0016] Figure 1 This is a principle block diagram of an X-ray tube filament current closed-loop control circuit according to an embodiment of the utility model;
[0017] Figure 2 This is a schematic diagram of a filament current control circuit according to an embodiment of the utility model;
[0018] Figure 3 This is a principle block diagram of an X-ray machine according to an embodiment of the utility model. DETAILED DESCRIPTION
[0019] The embodiments of the present invention are described in detail below. Figure 1 The embodiment of the utility model provides an X-ray tube filament current closed-loop control circuit, including a controller, a filament current control circuit, a tube current sampling circuit, a filament current sampling circuit, a tube current closed-loop circuit and a filament current closed-loop circuit. The output end of the filament current control circuit is connected to the cathode filament of the X-ray tube, and is used to adjust the current output to the cathode filament of the X-ray tube under the control of the controller, and drive the cathode filament of the X-ray tube to work. The input end of the tube current sampling circuit is connected to the anode of the X-ray tube, and is used to collect the tube current of the X-ray tube. The input end of the filament current sampling circuit is connected to the output end of the filament current control circuit, and is used to collect the filament current output to the cathode filament. The two input ends of the tube current closed-loop circuit are respectively connected to the output ends of the controller and the tube current sampling circuit, and the output end is connected to the control end of the filament current control circuit, and receives a tube current reference signal from the controller, and receives a tube current sampling signal converted from the tube current from the tube current sampling circuit. The tube current closed-loop circuit feeds back the error between the tube current sampling signal and the tube current reference signal to the control end of the filament current control circuit. The two input ends of the filament current closed-loop circuit are respectively connected to the output ends of the controller and the filament current sampling circuit, and the output end is also connected to the control end of the filament current control circuit, receiving the filament current reference signal from the controller and receiving the filament current sampling signal converted from the filament current from the filament current sampling circuit. The filament current closed-loop circuit feeds back the error between the filament current sampling signal and the filament current reference signal to the control end of the filament current control circuit.
[0020] In the X-ray tube filament current closed-loop control circuit of the embodiment of the utility model, the tube current closed-loop circuit and the filament current closed-loop circuit respectively feed back the error between the actual tube current and the tube current reference and the error between the actual filament current and the filament current reference to the control end in the filament current control circuit, and the filament current control circuit uses the larger error signal of the two error signals to adjust the current output to the cathode filament. By introducing the tube current feedback into the control of the filament current, the tube current feedback is indirectly involved in the control of the filament of the X-ray tube. When the tube current of the X-ray tube decreases due to the temperature characteristics or aging of the X-ray tube, the error between the tube current sampling signal and the tube current reference signal will become larger, greater than the error between the filament current sampling signal and the filament current reference signal, and the filament current control circuit will adjust the current output to the cathode filament according to the error between the tube current and the tube current reference, so that the dose of X-rays finally output by the X-ray tube meets the tube current reference given by the controller. The X-ray tube filament current closed-loop control circuit introduces tube current feedback into the control of filament current, so there is no need to calibrate the X-ray tube, and obtain the mapping relationship between the tube current and the filament current of the X-ray tube, thereby avoiding the tedious regular calibration process of the X-ray tube, and making it more convenient to use. In addition, during use, the control accuracy of the X-ray dose will not be affected by the aging of the X-ray tube or the temperature change after multiple exposures, and the X-ray dose can be controlled more accurately.
[0021] Reference Figure 1 , the tube current closed-loop circuit and the filament circuit closed-loop circuit can both be composed of operational amplifiers. The tube current closed-loop circuit includes a first operational amplifier, the inverting input terminal of the first operational amplifier is connected to the controller, and receives the tube current reference signal MA_REF given by the controller, the non-inverting input terminal of the first budget amplifier is connected to the output terminal of the tube current sampling circuit, and receives the tube current sampling signal RMA_FD, and the output terminal of the first operational amplifier is connected to the control terminal of the filament current control circuit. The filament current closed-loop circuit includes a second operational amplifier, the inverting input terminal of the second operational amplifier is connected to the controller, and receives the filament current reference signal FILE_REF given by the controller, the non-inverting input terminal of the second operational amplifier is connected to the output terminal of the filament current sampling circuit, and receives the filament current sampling signal FILE_FD, and the output terminal of the second operational amplifier is also connected to the control terminal of the filament current control circuit.
[0022] Reference Figure 2In this embodiment, the filament current control circuit includes a PWM controller and an inverter circuit. The output ends of the tube current closed-loop circuit and the filament current closed-loop circuit are both connected to the feedback end of the PWM controller. The output end of the PWM controller is connected to the gates of the two inverter tubes Q3 and Q5 of the inverter circuit. The PWM controller adjusts the duty cycle of the output PWM controller according to the larger error signal received at the feedback end, thereby adjusting the switching duty cycle of the two inverter tubes, thereby realizing the regulation of the current output from the inverter circuit to the cathode filament.
[0023] Reference Figure 2 In this embodiment, the PWM controller adopts a TL594 chip or a TL494 chip, which integrates an operational amplifier with two output ends connected to the feedback pin COMP pin. The tube current reference signal MA_REF given by the controller is output to the -V1 pin of the chip U15, and the output end of the tube current sampling circuit is connected to the +V1 pin of the chip U15. The filament current reference signal FILE_REF given by the controller is output to the -V2 pin of the chip U15, and the output end of the filament current sampling circuit is connected to the +V2 pin of the chip U15. In this embodiment, in order to improve the accuracy of the tube current closed-loop feedback and the filament current closed-loop feedback control, the tube current closed-loop circuit includes a tube current loop compensation circuit, and the filament current closed-loop circuit includes a filament current loop compensation circuit. The tube current loop compensation circuit includes tube current compensation resistors R65 and R67, and a tube current compensation capacitor C52. The tube current compensation resistor R67 and the pins of the tube current compensation capacitor C52 are connected in series between the -V1 pin and the COMP pin of the chip U15, and the tube current compensation resistor R65 is connected in parallel to the two ends of the series structure formed by the tube current compensation resistor R67 and the tube current compensation capacitor C52. The filament current loop compensation circuit includes a filament current compensation resistor R66 and a filament current compensation capacitor C54, the filament current compensation capacitor C54 is connected between the -V2 pin and the COMP pin of the chip U15, and the filament current compensation resistor R66 is connected in parallel to the two ends of the filament current compensation capacitor C54.
[0024] Reference Figure 2In this embodiment, the output pins E1 and E2 of the chip U15 are connected to the gate of the corresponding inverter tube through the MOSFET driver chip U14. In order to improve the stability of the filament current sampling, the input end of the filament current sampling circuit samples from the primary end of the inverter circuit output and is connected to the connection node of the two inverter tubes. In order to facilitate the switching of the working modes of the two closed-loop circuits, in this embodiment, the controller is also connected to the dead zone control pin DTC of the chip U15, and transmits the mode switching signal FI L_CON to the PWM controller. By changing the dead zone time of the PWM controller, the circuit is switched between the normal working mode and the filament current preheating mode. The output end of the filament current sampling circuit is also connected to the controller through a buffer, and the filament current feedback signal FI L_FD is output to the controller so that the controller can monitor the filament current. In this embodiment, the buffer adopts an emitter follower.
[0025] It is understandable that the filament current sampling circuit and the tube current sampling circuit are generally amplifier circuits or voltage divider circuits, which convert the sampled filament current and tube current into a suitable voltage range, and then send them to the input ends of the tube current closed-loop circuit and the filament current closed-loop circuit. The inverter circuit generally includes an inverter bridge composed of two inverter tubes and a transformer. The basic structures of the filament current sampling circuit, the tube current sampling circuit and the inverter circuit are common knowledge in the art and will not be elaborated here.
[0026] Reference Figure 3 The X-ray machine of the embodiment of the utility model includes the above-mentioned X-ray tube filament current closed-loop control circuit, and also includes an inverter boost circuit for applying a high-voltage electric field to the X-ray tube, and a tube voltage sampling circuit for sampling the voltage output from the inverter boost circuit to the X-ray tube, so as to form a closed-loop control of the high-voltage electric field. The X-ray machine can achieve stable control of the X-ray dose without calibrating the X-ray tube, and is not affected by changes in the mapping relationship between the tube current and the filament current caused by the temperature characteristics or aging of the X-ray tube itself.
[0027] It should be noted that in the description of the present invention, if there are any orientation descriptions, such as up, down, front, back, left, right, etc., the orientations or positional relationships indicated are all based on the orientations or positional relationships shown in the drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed or operated in a specific orientation, and cannot be understood as a limitation on the present invention.
[0028] In the description of the present utility model, "several" means one or more, "more" means two or more, "greater than", "less than", "exceed" etc. are understood to exclude the number itself, and "above", "below", "within" etc. are understood to include the number itself. If there is a description of "first" or "second", it is only used to distinguish the technical features, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the order of the indicated technical features.
[0029] In the description of the present invention, unless otherwise clearly defined, terms such as setting, installing, connecting, etc. should be understood in a broad sense, and technicians in the relevant technical field can reasonably determine the specific meanings of the above terms in the present invention based on the specific content of the technical solution.
[0030] The above-mentioned implementation modes are only preferred implementation modes of the present invention, and cannot be used to limit the protection scope of the present invention. Any non-substantial changes and substitutions made by technicians in this field on the basis of the present invention shall fall within the scope of protection required by the present invention.
Claims
1. A closed-loop control circuit for filament current of an X-ray tube, characterized in that: include: Controller; a filament current control circuit, used for driving the cathode filament of the X-ray tube under the control of the controller; A tube current sampling circuit, the input end of which is connected to the anode of the X-ray tube, and is used to collect the tube current of the X-ray tube; A filament current sampling circuit, the input end of which is connected to the output end of the filament current control circuit, and is used to collect the filament current output to the cathode filament of the X-ray tube; A tube current closed-loop circuit, wherein two input ends are respectively connected to the controller and the output ends of the tube current sampling circuit, receiving a tube current reference signal output by the controller and a tube current sampling signal output by the tube current sampling circuit, and an output end is connected to the control end of the filament current control circuit, and is used to feed back an error between the tube current sampling signal and the tube current reference signal to the control end of the filament current control circuit; A filament current closed-loop circuit, wherein two input ends are respectively connected to the output ends of the controller and the filament current sampling circuit, receiving a filament current reference signal output by the controller and a filament current sampling signal output by the filament current sampling circuit, and an output end is connected to the control end of the filament current control circuit, for feeding back the error between the filament current sampling signal and the filament current reference signal to the control end of the filament current control circuit.
2. The X-ray tube filament current closed-loop control circuit according to claim 1, characterized in that: The tube current closed-loop circuit includes a first operational amplifier, an inverting input terminal of the first operational amplifier is connected to the controller, a non-inverting input terminal of the first operational amplifier is connected to the output terminal of the tube current sampling circuit, and the output terminal of the first operational amplifier is connected to the control terminal of the filament current control circuit.
3. The X-ray tube filament current closed-loop control circuit according to claim 2, characterized in that: The tube current closed-loop circuit also includes a tube current loop compensation circuit, which includes a compensation resistor and a capacitor. The inverting input terminal of the first operational amplifier is connected to its output terminal through a first tube current compensation resistor and a tube current compensation capacitor. The two ends of the series structure formed by the first tube current compensation resistor and the tube current compensation capacitor are connected in series and connected in parallel by a second tube current compensation resistor.
4. The X-ray tube filament current closed-loop control circuit according to claim 1, characterized in that: The filament current closed-loop circuit includes a second operational amplifier, an inverting input terminal of the second operational amplifier is connected to the controller, a non-inverting input terminal of the second operational amplifier is connected to the output terminal of the filament current sampling circuit, and the output terminal of the second operational amplifier is connected to the control terminal of the filament current control circuit.
5. The X-ray tube filament current closed-loop control circuit according to claim 4, characterized in that: The filament current closed-loop circuit also includes a filament current loop compensation circuit, which includes a compensation resistor and a capacitor. The inverting input terminal of the second operational amplifier is connected to its output terminal through the filament current compensation capacitor, and the two ends of the filament current compensation capacitor are connected in parallel with a filament current compensation resistor.
6. The X-ray tube filament current closed-loop control circuit according to claim 1, characterized in that: The filament current control circuit includes a PWM controller and an inverter circuit. The output ends of the tube current closed-loop circuit and the filament current closed-loop circuit are both connected to the feedback end of the PWM controller. The output end of the PWM controller is connected to the gates of the two inverter tubes of the inverter circuit. The input end of the filament current sampling circuit is connected to the connection node of the two inverter tubes.
7. The X-ray tube filament current closed-loop control circuit according to claim 6, characterized in that: The dead zone control pin of the PWM controller is connected to the controller to receive a mode switching signal output by the controller.
8. The X-ray tube filament current closed-loop control circuit according to claim 6, characterized in that: The PWM controller adopts a TL594 chip or a TL494 chip.
9. The X-ray tube filament current closed-loop control circuit according to claim 1, characterized in that: The output end of the filament current sampling circuit is connected to the controller through a buffer.
10. An X-ray machine, characterized in that: The invention comprises the X-ray tube filament current closed-loop control circuit according to any one of claims 1 to 9.