JPS63166200A - Trouble discrimination circuit of x-ray high voltage generation device - Google Patents

Abstract

PURPOSE:To make it possible to discriminate trouble even in case a value on the positive electrode side or on the negative electrode side of a tube voltage is deviated, by outputting a trouble discrimination signal while comparing the absolute values of errors of both positive and negative components of X-ray tube voltage from an error amplifying circuit with a reference voltage. CONSTITUTION:An error amplifying circuit 17 takes the outputs 20 and 21 of a tube voltage detection circuit into an operation amplifier OP1 through resistances R5 and R6. The error amplifying outputs are inputted into an absolute value operation circuit 18 to output absolute values of errors of both positive and negative components into a comparator circuit 23. The circuit 23 sends out a trouble discrimination signal to an X-ray control circuit through a delay circuit 24 consisting of a resistance 14 and a capacitor C, a resistance 15 and a transistor Tr after comparing output potentials of the circuit 18 with a reference potential.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention is provided in an X-ray high voltage generator that generates a high voltage (referred to as tube voltage) applied to an X-ray tube, The present invention relates to a failure determination circuit that determines failure of the device.

(Conventional technology) Conventionally, high voltage resistance M'? An X-ray high-pressure generator that performs tube voltage control using a tube (hereinafter referred to as a tetrode) is provided with a failure determination circuit that determines a failure of the tetrode and shuts off X-ray generation. An example of this failure determination circuit includes a timer circuit that generates an X-ray exposure control signal, a bleeder resistor that is connected in parallel to the X-ray tube and obtains a predetermined partial pressure signal, and a signal from the timer circuit and the bleeder resistor. There is a device that is equipped with a device that performs a logical operation on the divided voltage signal from the bleeder circuit to determine a failure, and a circuit that processes the divided voltage signal from the bleeder circuit with a predetermined insensitive period. Showa 49-70864>.

(Problems to be Solved by the Invention) However, in the above circuit, only when high voltage is not applied to either the positive electrode side or the negative electrode side of the X-ray tube, that is, only when high voltage is applied to only one side, Since it was determined that there was a failure, high voltages were applied to both the positive and negative sides, and furthermore, if either of the -10,000 values were higher or lower than the set value, it would be impossible to determine the failure. Also, the rise of tube voltage.

In order to eliminate malfunctions caused by falling waveforms, insensitive periods are set at the beginning and end of the X-ray exposure time.
For this reason, it also has the disadvantage that it is not possible to determine the failure of a device abnormality that occurs during the insensitive period.

Therefore, the present invention eliminates the above-mentioned drawbacks, and makes it possible to determine a failure when the value on the positive or negative side of the tube voltage deviates from the set value. It is an object of the present invention to provide a failure determination circuit that can accurately detect equipment abnormalities that occur.

[Structure of the Invention] (Means for Solving Discrepancies) The present invention solves errors in both positive and negative components of the X-ray tube voltage based on the divided voltage output of a tube voltage voltage dividing means that divides the X-ray tube voltage. An error amplification circuit that obtains the error amplification output, an absolute value calculation circuit that obtains the absolute value of the error amplification output, and a comparator circuit that outputs a failure determination signal by comparing the obtained absolute value with a preset reference value. It is.

(Function) The error amplifier circuit calculates the error of both positive and negative components of the X-ray tube voltage, the absolute value calculation circuit calculates the absolute value of this error amplified output, and the comparator compares this absolute value with a reference value. Since the system performs this and outputs a failure determination signal, it is possible to determine this even if the value on the positive or negative side of the tube voltage deviates from the set value, and also without setting a dead period. Since abnormality detection is always performed, it is possible to accurately detect device abnormalities that occur when the tube voltage rises and falls.

(Example) An embodiment of the present invention will be described below.

FIG. 2 is a 10-step diagram of an X-ray high voltage generator equipped with a failure determination circuit according to the present invention. As shown in the figure, this device includes a high pressure generating section 1. High voltage control section 4, tube voltage dividing means 9
．． X-ray tube10. N release switch 12, X-ray control circuit 13. Tube voltage control circuit 14° tube voltage detection circuit 15. It has a failure determination circuit 16.

The high voltage generator 1 is a three-phase AC type via an electromagnetic switch 12!
It boosts the three-phase AC voltage taken in from 11 and outputs a DC high voltage by rectifying it, and includes a high-voltage transformer 2 that boosts the three-phase AC voltage, and a high-voltage rectifier that rectifies this boosted output. It has an element 3. The high voltage output of this high voltage generating section 1 has both positive and negative components with respect to the ground level, and these are sent to a high voltage control section 4 disposed at a subsequent stage.

The high voltage control section 4 obtains a predetermined tube voltage through high voltage control, and includes a positive tetrode 5 and its control circuit 6, and a negative tetrode and its control circuit 8. And the output of these tetrodes 5 and 7 is X-ray f
The voltage is applied to the anode and filament of f10, respectively.

The tube voltage dividing means 9 divides the tube voltage between the anode and the filament of the X-ray tube 10, and here, it is formed by connecting bleeder resistors R1, R2, R3, and R4 in series, and R2 , by grounding the connection point of R3,
A positive side partial voltage output and a negative side partial voltage output are obtained from the connection point of R1 and R2 and the connection point of R3 and R4, respectively.

The tube voltage detection circuit 15 performs impedance conversion of the divided voltage output from the tube voltage dividing means 9, and its output is sent to the tube voltage control circuit 14 and the failure determination circuit 16. ing.

This failure determination circuit 16 performs failure determination of this X-ray high voltage generator based on the output (positive component 20, negative component 21) of the tube voltage detection circuit 15, and its detailed configuration will be described later. .

The X-ray control circuit 13 controls the operation of the electromagnetic switch 12 according to the failure determination signal 22 from the failure determination circuit 16, and also generates a tube voltage setting signal and sends it to the tube voltage control circuit 14. This will be sent to.

This tube voltage control circuit 14 compares the output of the tube voltage detection circuit 15 and the tube voltage setting signal from the X-ray control circuit 13, and applies the comparison result to the tetrode i and II control circuits 6 and
It is part of a feedback control system for stabilizing tube voltage.

Next, the detailed configuration of the failure determination circuit will be explained based on FIG. 1. As shown in the figure, this failure determination circuit 16
is the error amplification circuit 17. Absolute value calculation circuit 18. Variable resistor 19. Comparator circuit 23, delay circuit 24. Resistance R
+s, and has a transistor Tr.

The error amplifying circuit 17 obtains an error in the positive and negative side components of the tube voltage based on the divided voltage output of the tube voltage dividing means 9.

Here, the divided voltage output is taken in via the tube voltage detection circuit 15. That is, the tube voltage detection circuit 15
The outputs 20 and 21 of the circuit are taken in through resistors Rs and R6, respectively, and inputted to the inverting input terminal (-) of an operational amplifier (hereinafter referred to as an operational amplifier) OP1. The non-inverting input terminal (+) of the operational amplifier OPi is grounded,
A resistor R7 is connected between the inverting input terminal and the output terminal. The error amplification output of this error amplification circuit 17 is sent to an absolute value calculation circuit 18 disposed at a subsequent stage.

This absolute value calculation circuit 18 calculates the absolute value of the output of the error amplification circuit 17, and has an input resistor R8 connected to the inverting input terminal of the operational amplifier OP2, and a diode connected between the output terminal of OF2 and the inverting input terminal. D1 is connected, the cathode side of the diode D2 is connected to the output terminal of OF2, the resistor R+o is connected between the anode side of D2 and the inverting input terminal, and the anode side of D2 is connected to the inverting input terminal of the operational amplifier OP3. A resistor Rn is connected between them, a resistor 1 (1o) is connected between one end of Rt+ and one end of R8, a resistor I'h2 is connected between the output terminal of OF2 and the inverting input terminal, and a resistor I'h2 is connected between the output terminal of OF2 and the inverting input terminal, The non-inverting input terminal of the absolute value calculation circuit 18 is grounded.The output of the absolute value calculation circuit 18 is sent to a comparator circuit 23 disposed at a subsequent stage.

This comparator circuit 23 outputs a failure determination signal by comparing the output potential (absolute value) of the absolute value calculation circuit 18 and a preset reference potential (reference value).
An input resistor RI3 is connected to the non-inverting input terminal of the operational amplifier OP4, a diode D3 is connected between the output terminal of OF2 and the inverting input terminal, and a 1g moving end of the variable resistor 19 is connected to the inverting input terminal of OF2. It consists of A positive potential is applied to one end of the variable resistor 19, and the other end is grounded, and the reference potential can be set by this single variable resistor. The base rP potential is set in consideration of the allowable potential difference between the positive and negative side components of the tube voltage. The failure determination signal from this comparator circuit 23 is transmitted to a delay circuit 24. Resistance R+5. The light is sent to the X-ray control circuit 13 via the transistor Tr.

Next, the operation of the above configuration will be explained.

The three-phase AC voltage from the three-phase AC power supply 11 is applied to the electromagnetic switch 12
(open state), a high voltage is induced in the secondary side of the high voltage transformer 2, and this high voltage is rectified by the high voltage rectifying element 3. It is then applied to the X-ray tube 10 via the tetrode 5.7. This X-ray tube applied voltage (tube voltage) is divided by the tube voltage voltage dividing means 9, and this divided voltage output is obtained by the tube voltage detection circuit 15.
The signal is inputted to the tube voltage control circuit 14 and the failure determination circuit 16 via. Then, the tube voltage control circuit 14 controls the tetrode control circuits 6 and 8 based on the output of the tube voltage detection circuit 15 (positive component 20, negative component 21) and the output of the X-ray control circuit 13 (tube voltage setting signal)! Sends I-fold signal and performs feedback control of tube voltage.

On the other hand, the output of the tube voltage detection circuit 15 (positive component 20 degrees, negative component 21) is also input to the error amplification circuit 17 of the failure determination circuit 16, and the error amplification circuit 17 amplifies the error of the positive and negative side components of the tube voltage. That will happen. Then, the absolute value of this error amplification output is determined by the absolute value calculation circuit 18 and sent to the comparator circuit 23. Then, the comparator circuit 23 compares the absolute value output potential of the absolute value calculation circuit 18 and the reference potential provided by the variable resistor 19.

In this potential comparison, if the absolute value output potential is lower than the reference potential, the output of the comparator circuit 23 becomes low level. This means that the device is working normally.

However, when the absolute value output potential is higher than the reference potential in the potential comparison of the comparator circuit 23, it means that the difference between the positive and negative side components of the tube voltage exceeds a predetermined value, and the comparator circuit 23 The output will be at a high level. When this high level state is maintained for a certain period of time, the transistor T
A current flows through the base of r, and a signal (failure determination signal 22) indicating that there is an abnormality in the apparatus is sent to the X-ray control circuit 13. This signal input causes the X-ray control circuit 13 to switch to the electromagnetic switch 1.
2 into the (I) state, and the application of three-phase AC voltage to the high-voltage transformer 2 is stopped.

Here, the delay circuit 24 acts to prevent the transistor Tr from turning on even if the output of the comparator circuit 23 temporarily becomes high level due to noise or the like. This prevents malfunction determination.

In this way, in this embodiment, the error amplifier circuit 17 calculates the error of the positive and negative side components of the tube voltage, and the absolute value calculation circuit 1
8 calculates the absolute value of this error amplified output, and the comparator circuit 23 compares the output potential of the absolute value calculation circuit 18 with the reference potential to output a failure determination signal. Alternatively, even if the value on the negative electrode side deviates from the set value, this can be determined. Furthermore, since abnormality detection is always performed without setting a dead application, it is possible to accurately detect abnormalities that occur when the tube voltage rises and falls. When the failure determination circuit according to the present invention is applied to an X-ray high-pressure generator using a tetrode, abnormalities due to deterioration of the tetrode and its control circuit components can be detected at the initial stage of deterioration. This has the advantage that failure can be determined before the high-voltage switching operation of the tetrode becomes defective, and destruction of the X-ray tube that would occur when the switching operation fails can be prevented.

Note that the present invention is not limited to the above embodiments. For example, in the above embodiment, the failure determination circuit was applied to an X-ray high voltage generator using a tetrode, but the failure determination circuit according to the present invention can also be applied to a device that switches tube voltage using a semiconductor switching element. be able to.

[Effects of the Invention] As detailed above, according to the present invention, it is possible to determine a failure when the value on the positive or negative side of the tube voltage deviates from the set value, and also to detect the rise of the tube voltage. , it is possible to provide a failure determination circuit that can accurately detect abnormalities that occur at the time of falling.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of a failure determination circuit which is an embodiment of the present invention.
FIG. 2 is a block diagram of an X-ray high voltage generator equipped with this failure determination circuit. 9...Tube voltage dividing means, 16...Failure determination circuit, 1
7...Error amplification circuit, 18...Absolute value calculation circuit, 2
3... Comparator circuit.

Claims (1)

[Claims] Faulty determination of the device is provided in an X-ray high-voltage generator that outputs an X-ray tube voltage consisting of both positive and negative components with reference to the ground level, and a malfunction of the device is determined from the divided voltage output of a tube voltage dividing means that divides the X-ray tube voltage. an error amplification circuit for obtaining errors in both positive and negative components of the X-ray tube voltage based on the divided voltage output of the tube voltage voltage dividing means; and an absolute value calculation circuit for obtaining the absolute value of the error amplification output. 1. A failure determination circuit for an X-ray high voltage generator, comprising: a comparator circuit that outputs a failure determination signal by comparing the determined absolute value with a preset reference value.