JP2004022439A - X-ray high voltage device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an x-ray high voltage device in which an x-ray tube or the like is protected from a tube voltage rise after a primary operation stop caused by discharge detection. <P>SOLUTION: After the discharge detection, when a high voltage generator 2 is recovered after a prescribed cease period, if a negative tube voltage comparator 4b detects that an abnormal voltage VO appeared on the side of a negative tube voltage reverse to that of a positive tube voltage in which discharge occurs, an AND circuit 38 is outputted by means of an output of a timer means 37 and an error signal 44, and a protective means is actuated to detect that a tube voltage applied to the x-ray tube 1 after the operation of a temporary stop means is higher than a value of a prescribed abnormal threshold, and to switch a switch 34 to the side where an output of the high voltage generator 2 decreases, and after that, the switch 34 is returned through a re-cease period, and the high voltage generator 2 is returned by a re-stop means 35. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an X-ray high-voltage device, and more particularly to an X-ray high-voltage device having a temporary stop means for resting after detecting a discharge in an X-ray tube and then resting for a certain period of time.
[0002]
[Prior art]
In a conventional X-ray high-voltage device, as described in, for example, JP-A-11-289789 and JP-A-2001-189200, the tube voltage is reduced in relation to the operation of returning from a minute discharge in an X-ray tube. If a discharge in the X-ray tube is detected due to a phenomenon such as a sudden drop or an increase in tube current, the operation is temporarily stopped. It is known that the discharge recovery process is performed again.
[0003]
[Problems to be solved by the invention]
However, in an X-ray high voltage device using an X-ray tube of a neutral grounding type, when a discharge S occurs between the positive side or the negative side of the tube voltage and the neutral point as shown in FIG. Even if the operation of the high-voltage generator is temporarily stopped after the detection, and the return process is performed after the pause period t1, the tube voltage in which the discharge S has not occurred increases and the overvoltage V0 appears, and the X-ray tube and the The electrical insulation of other circuit components may be damaged.
[0004]
An object of the present invention is to provide an X-ray high-voltage device capable of protecting an X-ray tube or the like from a tube voltage increase after a primary operation is stopped due to discharge detection.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a neutral grounded X-ray tube for generating X-rays, a high voltage generator for supplying a high voltage to the X-ray tube, and a high voltage generator applied to the X-ray tube. Voltage detection circuit for detecting a tube voltage to be detected, discharge detection means for detecting a discharge in the X-ray tube, and a temporary stop for resting the high voltage generator for a certain period of time upon detection by the discharge detection means. An X-ray high-voltage device comprising a stopping means, a protection means for detecting that a tube voltage applied to the X-ray tube after the temporary stopping means is operated is higher than an abnormal setting threshold, and And a re-stop means for lowering the output of the high voltage generator upon detection and returning the high voltage generator after a certain period of time.
[0006]
An X-ray high-voltage device according to the present invention comprises a protection means for detecting that a tube voltage applied to an X-ray tube after a temporary stop means is operated is higher than an abnormal setting threshold value, and the high voltage when the protection means is operated. Since the output of the voltage generator is reduced and the re-stop means for returning the high voltage generator after a certain period of time is provided, the tube voltage in which no discharge has occurred after the temporary stoppage of operation due to the detection of discharge in the X-ray tube rises When the voltage exceeds the abnormality setting threshold value, the protection means detects this and reduces the output of the high voltage generator, and after a certain period of time, the high voltage generator is returned by the re-stop means. It is possible to protect the X-ray tube and other circuit components from a rise in voltage and improve insulation.
[0007]
According to a second aspect of the present invention, in order to achieve the above object, the protection means according to the first aspect, wherein the high voltage generator is stopped after a predetermined period of time and then returned to a predetermined state. A timer means for monitoring until the tube voltage reaches a predetermined value, and detecting a tube voltage higher than the abnormality setting threshold during monitoring by the timer means.
[0008]
The X-ray high-voltage apparatus according to the second aspect of the present invention is provided with timer means for monitoring the period from when the high-voltage generator is restored after a period of inactivity for a predetermined period of time to when the high-voltage generator reaches a predetermined tube voltage. The means monitors the time from when the high voltage device returns after a certain period of inactivity until the tube voltage reaches a predetermined tube voltage according to the rising time constant of the tube voltage, and distinguishes from the other overvoltages and returns the high voltage generator to discharge. The occurrence of overvoltage on the opposite negative voltage side or positive voltage side can be reliably detected.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram showing an X-ray high-voltage device according to an embodiment of the present invention.
An X-ray CT apparatus (not shown in detail) is configured in the neutral-point grounded X-ray tube 1 so that a high-voltage DC voltage from the high-voltage generator 2 is applied to emit X-rays. ing. The X-ray tube 1 is provided with a positive tube voltage detecting circuit 41 for detecting a positive tube voltage and a negative tube voltage detecting circuit 42 for detecting a negative tube voltage. 4 has been sent. The signal from the tube voltage measuring unit 4 is supplied to the high voltage generator 2 via the high voltage control unit 3, and the high voltage generator 2 is controlled.
[0010]
The tube voltage measuring unit 4 includes a positive tube voltage comparator 4a that detects that the positive tube voltage detected by the positive tube voltage detection circuit 41 has exceeded a predetermined threshold, and a negative tube voltage that is detected by the negative tube voltage detection circuit 42. A negative tube voltage comparator 4b for detecting that the side tube voltage has exceeded a predetermined threshold value, and a tube voltage detector 4c for detecting the tube voltage from the sum of the positive tube voltage detection circuit 41 and the negative tube voltage detection circuit 42 are provided. Is provided. The outputs of the positive tube voltage comparator 4a and the negative tube voltage comparator 4b are respectively input to an OR circuit 39, and the OR circuit 39 outputs an error signal 44 when one of the tube voltages exceeds a predetermined threshold. It is configured as follows.
[0011]
The high voltage control unit 3 is provided with a regulator circuit 32. The regulator circuit 32 receives the tube voltage detection value 40 from the tube voltage detector 4c of the tube voltage measurement unit 4 and compares it with the tube voltage target value 30. The control amount 31 is output to the high voltage generator 2 via the switch 32. The high-voltage control section 3 includes a discharge detecting means 33 for detecting a discharge in the X-ray tube 1 as will be described later in detail, and a high-voltage generator 2 for a predetermined period when the discharge detecting means 33 detects the discharge. Suspending means for returning after pausing, protecting means for detecting that the tube voltage applied to the X-ray tube 1 after the suspending means is operated is higher than an abnormal setting threshold, and when the protecting means is operated The high voltage generator 2 constitutes a re-stop means 35 for lowering the output for a certain period and thereafter returning the high voltage generator 2.
[0012]
The above-mentioned discharge detecting means 33 takes in the tube voltage detection value 40 from the tube voltage detector 4c of the tube current measuring section 4 into the discharge detecting means 33, and detects the occurrence of discharge from the voltage change rate or the like. Further, the temporary stop means supplies the detection signal of the discharge detection means 33 to the switch 34 via the timer means 36, switches the switch to the Rlow side, that is, the stop side, and stops the high voltage generator 2, and the timer means 36 After counting a predetermined time, the switch 34 is switched to the original state, and the high-voltage generator 2 is returned.
[0013]
Further, the above-mentioned protection means has a timer means 37 which starts counting from the time when the discharge detection means 33 detects the discharge and counts until the rated tube voltage is reached in consideration of the rising time constant of the tube voltage. The output of the timer means 37 is used as a first condition, and an error of the OR circuit 39 when one of the positive tube voltage comparator 4a and the negative tube voltage comparator 4b detects an abnormal voltage exceeding a predetermined threshold value. The signal 44 is supplied to the AND circuit 38 as a second condition, so as to detect that the tube voltage applied to the X-ray tube 1 after the above-mentioned temporary stop means is operated is higher than the abnormal setting threshold value. Further, the above-mentioned re-stop means 35 switches the switch 34 to the Rlow side when there is an output of the AND circuit 35 to lower the output of the high voltage generator 2 and, when the timer means 40 has passed a predetermined time, the switch 34 And the high voltage generator 2 is restored.
[0014]
FIG. 2 is a waveform diagram showing the tube voltage of the X-ray tube showing the operation of the above-mentioned X-ray high voltage device.
When the discharge S occurs on the positive tube voltage side as shown in the figure, the discharge detection means 33 shown in FIG. 1 finally detects that the discharge S has occurred from the rate of change of the tube voltage detection value. The detection result is provided from the discharge detecting means 33 to the switch 34 via the timer means 36, and the switch 34 is supplied to the Rlow side, that is, as a signal for stopping the high voltage generator 2. However, after the elapse of the quiescent period t1 determined by the predetermined time period set by the timer means 36, the switching signal is stopped, the switch 34 is returned, and the high voltage generator 2 is returned.
[0015]
When the high voltage generator 2 returns, the tube voltage rises in accordance with the rising time constant as shown in FIG. 2, but until the predetermined tube voltage is reached, the tube voltage becomes abnormal on the negative tube voltage side opposite to the positive tube voltage side where the discharge S occurred. When the voltage V0 appears and the negative tube voltage comparator 4b detects that the abnormal voltage V0 detected by the negative tube voltage detection circuit 42 shown in FIG. 1 exceeds a predetermined threshold, the OR circuit 39 outputs an error signal 44. I do. The discharge detecting means 33 has already detected that the discharge S has occurred from the rate of change of the detected tube voltage value, and from this time the timer means 37 has started counting, and the output of the timer means 37 and the error signal 44 As a result, the AND circuit 38 outputs, and the protection means for detecting that the tube voltage applied to the X-ray tube 1 is higher than the abnormal setting threshold after the temporary stop means has been activated has been activated.
[0016]
Then, the output of the AND circuit 38 causes the re-return means 35 to output a signal to switch the switch 34 to the Rlow side, that is, the side to decrease the output of the high-voltage generator 2, so that the negative tube voltage decreases as shown in FIG. I do. Thereafter, the negative tube voltage drop is detected by the negative tube voltage comparator 4b, and the error signal 44 is released and the output of the AND circuit 38 is cut off, or the timer means 40 passes a predetermined time limit, and the resetting means is reset. Reference numeral 35 indicates that the switch 34 is restored after the rest period t2 shown in FIG. 2 and the high voltage generator 2 is restored. When the protection means is activated, the high voltage generator 2 is stopped for a certain period of time and thereafter the high voltage generator 2 is stopped. This means that the re-stop means 35 for returning the generator 2 has been activated.
[0017]
Thus, the X-ray high-voltage device is provided with the discharge detecting means 33 for detecting the discharge in the X-ray tube 1 with respect to the discharge generated on the positive voltage side or the negative voltage side of the X-ray tube 1. The provision of the suspending means for stopping after stopping the high voltage generator 2 for a predetermined pause time t1 when the detection by the means 33 is provided, allows the high voltage generator 2 to return in a predetermined discharge return period. . Moreover, even if an overvoltage V0 occurs on the opposite negative voltage side or positive voltage side during the recovery, the signal from the timer means 37 and the error signal 44 from the negative tube voltage comparator 4b or the positive tube voltage comparator 4a are generated. Detects that the tube voltage applied to the X-ray tube 1 is higher than the abnormal setting threshold after the temporary stop means has been activated, and when the protection means detects this, the high voltage is applied. Since the output of the generator is reduced and the high voltage generator 2 can be restored after a certain period of time t2, the X-ray tube 1 and other circuit components can be protected from the overvoltage V0.
[0018]
Further, a timer means 37 is provided which is activated when the discharge S is detected by the discharge detection means 33. The timer means 37 is provided with a predetermined time constant based on a rising time constant of the tube voltage from the return of the high-voltage device 2 after the elapse of the quiescent period t1. Since the setting up to the tube voltage is set, the occurrence of the overvoltage V0 on the opposite negative voltage side or the positive voltage side during the return of the high voltage generator 2 to the discharge S is reliably detected separately from other overvoltages. be able to.
[0019]
【The invention's effect】
As described above, according to the X-ray high-voltage device of the present invention, when a discharge occurs between the positive side or the negative side of the tube voltage and the neutral point in the X-ray tube of the neutral point grounding method, it is temporarily stopped. In addition to stopping the operation and performing the recovery process, during the recovery process, even if the tube voltage where discharge did not occur increases and an overvoltage occurs, it can be recovered after pausing again for a certain period of time. Thus, the X-ray tube and other circuit components can be protected from overvoltage to improve insulation.
[Brief description of the drawings]
FIG. 1 is a block diagram showing an X-ray high voltage device according to an embodiment of the present invention.
FIG. 2 is a tube voltage waveform chart showing an operation of the X-ray high voltage device shown in FIG.
FIG. 3 is a tube voltage waveform diagram showing an operation of a conventional X-ray high voltage device.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 X-ray tube 2 High voltage generator 3 High voltage control part 4 Tube voltage measuring part 4a Positive tube voltage comparator 4b Negative tube voltage comparator 4c Tube voltage detector 33 Discharge detecting means 34 Switch 35 Re-return means 36, 37 Timer Means 38 AND circuit 39 OR circuit 40 Timer means

Claims (2)

A neutral-point grounded X-ray tube that generates X-rays, a high-voltage generator that supplies a high voltage to the X-ray tube, a voltage detection circuit that detects a tube voltage applied to the X-ray tube, An X-ray high-voltage device comprising: discharge detection means for detecting discharge in the X-ray tube; and pause means for restoring the high-voltage generator after a predetermined period of time when it is detected by the discharge detection means. In the above, protection means for detecting that the tube voltage applied to the X-ray tube after the temporary stop means is operated is higher than an abnormal setting threshold value, and the detection of the high voltage generator An X-ray high-voltage device comprising a re-stop means for lowering the output and returning the high-voltage generator after a certain period of time. 2. The protection means according to claim 1, wherein said protection means includes timer means for monitoring a period from when the high voltage generator is stopped after a predetermined period of time is restored to when a predetermined tube voltage is reached. An X-ray high-voltage device for detecting a tube voltage higher than an abnormality setting threshold during monitoring.

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