JPH103997A - Inverter type x-ray high-voltage device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To miniaturize a device and improve the X-ray radiation quality by concurrently, conducting a part of the X-ray control process during the A/D-conversion of the tube voltage detection signal, accelerating the digital feedback control process, and increasing the inverter frequency. SOLUTION: The target tube voltage signal Vr, inverter input voltage detection signal Vi, and tube voltage detection signal Vo are inputted to a tube voltage digital feedback control device 8', and the inverter control signal S is outputted so that the signal Vo of an X-ray tube 5 becomes the desired voltage. The control device 8' using a micro-controller incorporating an A/D- converter is provided with the first and second comparing means 9, 13, integration, proportion, and differentiation adjusting means 10, 11, 12, input voltage and stationary characteristic correcting means 14, 15, and the first and second A/D-converters 16, 17. The abnormality process including the abnormality check of a device and an action when an abnormality occurs is conducted during the A/D-conversion action of the signal Vo, and the calculation required for the feedback control process is conducted during the A/D-conversion action of the signal Vi.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inverter type X-ray converter for converting a direct current from a direct current power supply into an alternating current using an inverter, boosting it, rectifying it, supplying it to an X-ray tube, and emitting X-rays. Inverter type X using line high voltage device, especially digital feedback control device requiring high speed operation
The present invention relates to improvement of a line high voltage device.

[0002]

2. Description of the Related Art A conventional inverter type X-ray high voltage apparatus, in particular, X-ray is controlled by controlling the phase difference and frequency of an inverter.
An X-ray high-voltage device capable of controlling a tube voltage applied to a tube has been configured as shown in FIG. That is, a DC power supply 1 that rectifies a single-phase or three-phase commercial power supply to obtain a DC voltage, receives a DC voltage from the DC power supply 1, converts it to an AC voltage, and controls an output voltage (tube voltage). An inverter 2, a high-voltage transformer 3 for boosting the AC voltage from the inverter 2, a high-voltage rectifier circuit 4 for converting the output voltage of the high-voltage transformer 3 to DC, An X-ray tube 5 to which a DC voltage is applied to emit X-rays; an inverter input voltage detector 6 connected to the input side of the inverter 2 to detect the inverter input voltage; and an output side of the high voltage rectifier circuit 4 A tube voltage detector 7 connected to detect the tube voltage of the X-ray tube 5, a desired target tube voltage signal Vr externally supplied, an input voltage detection signal Vi from the inverter input voltage detector 6, and the tube voltage detection Tube voltage detection signal Vo from 7 are input to the comparison operation between the target tube voltage signal Vr and the tube voltage detection signal Vo,
The X-ray tube 5 is provided with a feedback control device 8 that sends a control signal S to the inverter 2 to control the tube voltage of the X-ray tube 5 to a desired voltage. Then, the feedback control device 8 controls the target tube voltage signal Vr.
A first comparing means 9 for inputting the tube voltage detection signal Vo and calculating a difference between the two, an integration adjusting means 10 for inputting the calculation result to obtain an integrated value thereof, Proportional adjusting means 11 for inputting and multiplying by a constant, and differential adjusting means 12 for inputting and differentiating the tube voltage detection signal Vo
A second comparing means 13 for inputting the integral value from the integral adjusting means 10, the constant multiple value from the proportional adjusting means 11 and the differential value from the differential adjusting means 12 and subtracting the integral value; The signal generated by the second comparing means 13 and the inverter input voltage detection signal Vi are input to the second
Input voltage correcting means 14 for correcting the signal generated by the comparing means 13 by the fluctuation of the inverter input voltage.
And the output of the input voltage compensator 14 is input, and the control signal S of the inverter 2 is finally determined in accordance with the output characteristics of the device.
It consisted of

Here, various arithmetic means in the feedback control device 8 may be constituted by a hardware arithmetic unit such as an operational amplifier, or may be operated by a program using a microprocessor, a signal processor, or a microcontroller. Some were made to run. For example, the feedback control device 8 has an internal configuration (DSP (Digit
al Signal Processor)), and a digital feedback control system having the same configuration). In such a feedback control device 8, the A / D converters 16 and 17 convert the inverter input voltage detection signal Vi and the tube voltage detection signal Vo into digital signals by the A / D converters 16 and 17, and convert the signals into digital signals.
When the required operation is performed to calculate the inverter control signal S such as the operation phase difference of the inverter 2, the A / D conversion by the A / D converters 16 and 17 is conventionally started as shown in FIG. During the time (standby time) from the start of the A / D conversion to the end of the A / D conversion (standby time), no processing other than the A / D conversion mainly for calculating the phase difference was performed. In addition, this A / D conversion has a conversion time peculiar to the element, but at present it takes at least 7 to 10 μs even for a high-speed one. Therefore, in the conventional device shown in FIG. 5, two of the tube voltage detection signal Vo and the inverter input voltage detection signal Vi must be A / D converted, so that at least about 20 μs is spent for A / D conversion. become. FIG. 6 shows the flow of processing (digital feedback control processing) from the start of A / D conversion to the output of the inverter control signal S in the conventional device shown in FIG. On the other hand, in the inverter type X-ray high voltage apparatus, on the other hand, the rise time of the tube voltage is 1 ms or less, and the tube voltage waveform with small pulsation even in the steady state is also used for improving the X-ray quality (diagnosis image quality). There is a strong demand. Furthermore,
There is a strong demand for smaller and lighter devices in order to reduce the installation area and improve operability. To meet these requirements,
Increasing the frequency of the inverter frequency is an unavoidable factor, and the inverter frequency is currently 10 kHz or more. On the other hand, the sampling operation for obtaining the A / D conversion value and the output of the inverter control signal S are required to be performed once in one cycle of the operation of the inverter 2, so that the digital feedback processing including the A / D conversion is required. The time allowed is as short as several tens of μs. During the short time of several tens of μs, one A / D
If the conversion takes 7 to 10 μs, there is no time to perform the operation for calculating the phase difference or other necessary processing, and it is impossible to increase the frequency. 4 and 5, reference numeral 20 denotes a resonance capacitor.
5, the same reference numerals as those in FIG. 4 denote the same or corresponding parts.

[0004]

As described above, the conventional feedback control device 8 uses a digital feedback control system having an internal configuration as shown in FIG. 5 and employs a control processing sequence as shown in FIG. In the device, there is a limit to speeding up the control processing, and it is impossible to increase the inverter frequency. For this reason, there has been a problem that the size and weight of the apparatus cannot be reduced and the X-ray quality cannot be improved.

SUMMARY OF THE INVENTION An object of the present invention is to provide an inverter type X-ray high-voltage device capable of increasing the speed of digital feedback control processing, and thus increasing the frequency of an inverter, thereby reducing the size and weight of the device and improving X-ray quality. Is to provide.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a DC power supply, an inverter for converting DC from the DC power supply to an AC, a high voltage transformer for boosting an AC voltage from the inverter, and a high voltage transformer. A high voltage rectifier circuit for rectifying the output voltage of the vessel, an X-ray tube to which a DC voltage from the high voltage rectifier circuit is applied to emit X-rays, and an X-ray tube connected to the output side of the high voltage rectifier circuit A tube voltage detector for detecting a tube voltage of a tube, and at least a desired target tube voltage signal and a tube voltage detection signal from the tube voltage detector are input;
A tube voltage digital feedback control device for controlling the inverter so that the tube voltage of the tube becomes a desired voltage, wherein the tube voltage digital feedback control device comprises at least the tube This is achieved by providing an A / D converter for A / D converting a voltage detection signal, and performing a part of processing required for X-ray control in parallel during the A / D conversion operation. The tube voltage digital feedback control device checks at least at the time of the A / D conversion operation of the tube voltage detection signal whether or not an abnormality has occurred in the device during operation, for example, at the time of occurrence of an abnormality. Abnormality processing for detecting the abnormality and taking appropriate measures is performed in parallel. As a result, the entire digital feedback control process is speeded up, the frequency of the inverter can be increased, the size and weight of the device can be reduced, and the X-ray quality can be improved.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of an inverter type X-ray high voltage device according to the present invention.
This inverter-type X-ray high-voltage device converts DC from a DC power supply into AC using an inverter, boosts it, rectifies it, supplies it to an X-ray tube, and emits X-rays. , A DC power supply 1, an inverter 2,
A high-voltage transformer 3, a high-voltage rectifier circuit 4, an X-ray tube 5,
An inverter input voltage detector 6, a tube voltage detector 7, and a tube voltage digital feedback control device 8 'are provided.

Here, the DC power supply 1 is a device for supplying DC power, and here rectifies AC power of a 50 Hz or 60 Hz single-phase or three-phase commercial power supply with a rectifying element such as a diode and smoothes a capacitor or the like. It is configured to output a DC voltage by smoothing with an element. The inverter 2 receives a DC voltage output from the DC power supply 1 and converts it into an AC voltage, and also controls a voltage (tube voltage) output to the X-ray tube 5. The high-voltage transformer 3 boosts the AC voltage from the inverter 2, and has a primary winding connected to the output side of the inverter 2. The high voltage rectifier circuit 4 rectifies the output voltage of the high voltage transformer 3. The X-ray tube 5 includes a high-voltage rectifier circuit 4
The X-ray radiator emits X-rays when an output voltage is applied thereto, and is connected to the output side of the high-voltage rectifier circuit 4. The inverter input voltage detector 6 is connected to the input side of the inverter 2 at the output side of the DC power supply 1, detects the inverter input voltage, and sends it to the tube voltage digital feedback control device 8 'as an inverter input voltage detection signal Vi. Things. Further, the tube voltage detector 7 detects the tube voltage applied to the X-ray tube 5 and sends it to the inverter 2 as a tube voltage detection signal Vo.
Is connected to the input side.

The tube voltage digital feedback control device 8 ′ includes a desired target tube voltage signal Vr, an inverter input voltage detection signal Vi detected by the input voltage detector 6, and a tube voltage detection signal detected by the tube voltage detector 7. Vo is input, a desired target tube voltage signal Vr is compared with a tube voltage detection signal Vo, and the tube voltage detection signal Vo of the X-ray tube 5 is set to a desired voltage (the tube voltage of the X-ray tube 5 is a desired target). (Inverter control signal S) to the inverter 2 so as to reach the tube voltage. Here, the tube voltage digital feedback control device 8 'uses a microcontroller having an A / D converter for controlling the tube voltage. The tube voltage digital feedback control device 8 ′ under program control using this microcontroller includes a first comparing means 9, an integral adjusting means 10, and a proportional adjusting means 1.
1. Differential adjusting means 12, second comparing means 13, input voltage correcting means 14, steady-state characteristic correcting means 15, first A / D converter 16, and second A / D converter 17 are provided. . In this case, the first comparing means 9 outputs the target tube voltage signal Vr and the tube voltage detection signal V detected by the tube voltage detector 7.
Input o to calculate the difference between the two. The integration adjusting means 10 is for inputting the operation result of the first comparing means 9 and obtaining the integrated value. The proportional adjustment means 11 receives the tube voltage detection signal Vo and multiplies it by a constant.
The differentiating means 12 receives the tube voltage detection signal Vo and differentiates it. The second comparing means 13 receives the integral value from the integral adjusting means 10, the constant multiple value from the proportional adjusting means 11 and the differential value from the differential adjusting means 12, and subtracts the integral value. . The input voltage correcting means 14 is for inputting the signal generated by the second comparing means 13 and for inputting the inverter input voltage detection signal Vi to correct the fluctuation of the inverter input voltage. The steady-state characteristic correcting means 15 performs a correction process in consideration of the steady-state output characteristic of the device, and finally determines the inverter control signal S and sends it to the inverter 2. The first A / D converter 16 performs A / D conversion on the inverter input voltage detection signal Vi. The second A / D converter 17 A / D converts the tube voltage detection signal Vo.

Here, in the present invention, as shown in FIG. 3, the A / D conversion start-up is performed by the program necessary for the feedback control process in the tube voltage digital feedback control device 8 'and other processes. Actively utilize the time (at the time of A / D conversion operation) from after (start of A / D conversion) to acquisition of A / D conversion value (end of A / D conversion), ie, other than A / D conversion such as feedback calculation A part of the processing necessary for the X-ray control is performed in parallel with the A / D conversion operation.

Next, the general operation of the inverter type X-ray high voltage device configured as described above will be described. First, a target tube voltage signal Vr input from the outside and a tube voltage detection signal Vo from the tube voltage detector 7 that has been A / D converted by the A / D converter 17 in the tube voltage digital feedback control device 8 '. Is input to the first comparing means 9. Then, the difference between the two is calculated by the first comparison means 9, and the calculation result is input to the integration adjustment means 10. The integration adjusting means 10 integrates the result of the above calculation to obtain a second
To the comparing means 13. The tube voltage detection signal Vo after the A / D conversion is supplied to the proportional adjusting means 11 and the differential adjusting means 12 in the tube voltage digital feedback control device 8 '.
Each is entered. Then, the proportional adjustment means 11 sets A /
The D-converted tube voltage detection signal Vo is multiplied by a constant, and the differential adjusting unit 12 differentiates the tube voltage detection signal Vo and sends it to the second comparison unit 13. As a result, the second comparing means 13 subtracts the output of the integration adjusting means 10 and inputs the calculation result to the input voltage correcting means 14. The input voltage correction means 14 also supplies the inverter input voltage detection signal Vi from the inverter input voltage detector 6 with A
After being A / D converted by the / D converter 16, it is input. Then, the input voltage correcting means 14 performs a correction operation for correcting the fluctuation of the inverter input voltage by multiplying the result obtained by the second comparing means 13 by a reciprocal of the inverter input voltage. The result of the correction operation by the input voltage correction means 14 is further input to the steady-state characteristic correction means 15, subjected to a correction process in consideration of the steady-state output characteristics of the device, and then outputs an inverter control signal S according to the processing result. Will be. This inverter control signal S is the target tube voltage signal Vr
The switching timing (phase) of each switching element (not shown) of the inverter 2 is determined according to the inverter control signal S. The inverter 2 operates according to the inverter control signal S, that is, the DC power supply 1 DC voltage to an AC voltage. After this AC voltage is sent to the high-voltage transformer 3 and boosted, it is rectified into a DC voltage by the high-voltage rectifier circuit 4, and a high-voltage DC voltage is applied to the X-ray tube 5 to emit X-rays. .

Next, the specific operation of the tube voltage digital feedback control device 8 'in the device of the present invention will be described with reference to FIG. FIG. 3 is a diagram showing a flow of processing (digital feedback control processing) from the start of A / D conversion to the output of the inverter control signal S in the tube voltage digital feedback control device 8 ', and a series of processing shown here. Is the operation of inverter 2
It is performed every cycle. The processing required for the feedback control includes the above-described calculation of the integral value, the proportional value, and the differential value for performing the feedback control of the tube voltage, the feedback processing for performing the four arithmetic operations for correction, and the like. And an output process for generating and outputting an inverter control signal S, and further, an abnormality process for checking whether or not an abnormality has occurred in the device during operation, and for detecting an abnormality when an abnormality occurs and taking appropriate measures. In the example shown in FIG. 3, during the standby time from the start of the A / D conversion of the tube voltage (tube voltage detection signal Vo) to the end of the A / D conversion (during the A / D conversion operation), the above-described abnormality processing and other operations are performed. A suitable process is performed, and a feedback control process is required during a standby time (A / D conversion operation) from the start of A / D conversion of the inverter input voltage (inverter input voltage detection signal Vi) to the end of the A / D conversion. Here, for example, calculation, integral calculation, proportional calculation, and differential calculation are performed.

As described above, in the apparatus of the present invention, in the tube voltage digital feedback control processing, the standby time (at the time of the A / D conversion operation) from the start of the A / D conversion to the end of the A / D conversion is determined by the A / D conversion operation. The A / D conversion operation and other processing are performed in parallel with the use of some of the processing required for X-ray control other than the above, in other words, the A / D conversion operation is performed in parallel. As a result, the entire digital feedback control process is speeded up, the frequency of the inverter can be increased, the size and weight of the device can be reduced, and the X-ray quality can be improved.

FIG. 2 is a block diagram showing a second preferred embodiment of the present invention. The embodiment of FIG. 2 exemplifies a case where a controller without a built-in A / D conversion function, here a DSP, is used. In this case, A
A / D converters 16 and 17 are provided, and buffers 18 and 19 are provided between the A / D converters 16 and 17 and the DSP.
The circuit configuration is to take in the port of P. According to such a configuration, the A / D conversion operation and other processing can be performed in parallel, the entire digital feedback control processing can be speeded up, the inverter frequency can be increased, and the apparatus can be reduced in size and weight. And X-ray quality is improved.

FIG. 3 illustrates the flow of the digital feedback control processing in the apparatus of the present invention, in particular, the parallel processing target during the A / D conversion standby time (during the A / D conversion operation) of the tube voltage (tube voltage detection signal Vo). It is not limited to the ones. For example, since the fluctuation of the inverter input voltage is very slow as compared with the frequency of the inverter 2, it is necessary to use digital data of the inverter input voltage (inverter input voltage detection signal Vi) obtained by the previous A / D conversion. There is no significant effect. From this,
The correction process of the inverter input voltage is performed by the inverter input voltage (inverter input voltage detection signal Vi) as shown in FIG.
Can be performed after the A / D conversion operation is completed, a part of the A / D conversion operation can be performed using the A / D conversion standby time (during the A / D conversion operation) of the tube voltage (tube voltage detection signal Vo). is there. Further, in the above-described embodiment, the series of processes illustrated in FIG. 3 is performed once in one cycle of the operation of the inverter 2, but may be performed a plurality of times in one cycle as necessary. Further, in the above-described embodiment, as the adjusting means in the tube voltage digital feedback control device 8 ', the integral adjusting means 10, the proportional adjusting means 11, and the differential adjusting means 12 are provided.
Although the case where the combination of and was used was described,
A combination of any two of these adjusting means 10 to 12 may be used, or only the integral adjusting means 10 or the proportional adjusting means 11 may be used. In the above-described embodiment, the numerical value acquired by the A / D conversion is two of the inverter input voltage (the inverter input voltage detection signal Vi) and the tube voltage (the tube voltage detection signal Vo).
However, if necessary, another detection signal, for example, a tube current detector for detecting a current (tube current) flowing through the X-ray tube is provided, and the tube current detection signal is A / D-converted. It may be used for digital feedback control. Further, the DC power supply 1 only needs to generate a DC voltage, and is not limited to the configuration shown in FIGS. 1 and 2 and may be, for example, a battery. In addition, even when a large output power is obtained, there is no voltage drop, and when an ideal DC power supply with extremely small voltage fluctuations and pulsations is used as the DC power supply 1, or when an input voltage fluctuation is caused by an output voltage (tube voltage). ) May be affected,
Inverter input voltage (Inverter input voltage detection signal V
The A / D conversion value acquisition and inverter input voltage correction means 14 of i) may be omitted. In the embodiment shown in FIGS. 1 and 2, the resonance capacitor 20 is connected to the output side of the inverter 2, but the resonance capacitor 20 has a high frequency due to the leakage inductance of the high-voltage transformer 3. It is inserted for the purpose of improving that the current does not sufficiently flow through the windings of the high-voltage transformer 3, and therefore need not be inserted if the above-mentioned improvement is not necessary. Further, in the above-described embodiment, the method of controlling the tube voltage by the phase difference of the inverter 2 has been described. However, the tube voltage may be controlled by another control method such as pulse width modulation or frequency modulation.

[0016]

As described above, according to the present invention, during the A / D conversion operation of the tube voltage detection signal and the like, a part of the processing necessary for the X-ray control is performed in parallel. There is an effect that the speed of the entire feedback control process can be increased, the inverter frequency can be increased, and the size and weight of the device can be reduced and the X-ray quality can be improved. If the tube voltage digital feedback control device is provided with a microcontroller with a built-in A / D converter, the number of device components can be reduced, and the device configuration can be reduced in size and cost.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of the device of the present invention.

FIG. 2 is a block diagram showing a second preferred embodiment of the device of the present invention. It is.

FIG. 3 is a diagram showing a flow of processing from the start of A / D conversion to the output of an inverter control signal in the device of the present invention.

FIG. 4 is a block diagram showing a conventional device.

FIG. 5 is a block diagram showing a conventional digital feedback control type inverter type X-ray high voltage device.

6 is a diagram showing a flow of processing from the start of A / D conversion to the output of an inverter control signal in the conventional device shown in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 DC power supply 2 Inverter 3 High voltage transformer 4 High voltage rectifier circuit 5 X-ray tube 6 Inverter input voltage detector 7 Tube voltage detector 8 Feedback control device 8 'Tube voltage digital feedback control device 9 First comparison means 10 Integration Adjusting means 11 Proportional adjusting means 12 Differential adjusting means 13 Second comparing means 14 Input voltage correcting means 15 Steady-state characteristic correcting means 16 First A / D converter 17 Second A / D converter 18 First buffer 19 Second buffer 20 Resonant capacitor Vr Desired target tube voltage signal Vi Inverter input voltage detection signal Vo Tube voltage detection signal.

Claims (3)

[Claims] 1. A DC power supply, an inverter for converting DC from the DC power supply to AC, a high-voltage transformer for boosting an AC voltage from the inverter, and a high-voltage transformer for rectifying an output voltage of the high-voltage transformer. A voltage rectifier circuit, an X-ray tube to which a DC voltage from the high voltage rectifier circuit is applied to emit X-rays, and a tube connected to an output side of the high voltage rectifier circuit for detecting a tube voltage of the X-ray tube A voltage detector, a tube voltage for receiving at least a desired target tube voltage signal and a tube voltage detection signal from the tube voltage detector, and controlling the inverter so that the tube voltage of the X-ray tube becomes a desired voltage. In the inverter type X-ray high voltage device comprising a digital feedback control device, the tube voltage digital feedback control device converts at least the tube voltage detection signal into an A / D signal.
An X-ray high-voltage device comprising an A / D converter for performing D-conversion and performing a part of processing required for X-ray control in parallel during the A / D conversion operation. 2. A DC power supply, an inverter for converting DC from the DC power supply to AC, a high-voltage transformer for boosting an AC voltage from the inverter, and a high-voltage transformer for rectifying an output voltage of the high-voltage transformer. A voltage rectifier circuit, an X-ray tube to which a DC voltage from the high voltage rectifier circuit is applied to emit X-rays, and a tube connected to an output side of the high voltage rectifier circuit for detecting a tube voltage of the X-ray tube A voltage detector, an inverter input voltage detector connected to the input side of the inverter for detecting the inverter input voltage, a desired target tube voltage signal, a tube voltage detection signal from the tube voltage detector, and the inverter input voltage detection A tube voltage digital feedback control device that receives the inverter input voltage detection signal from the heater and controls the inverter so that the tube voltage of the X-ray tube becomes a desired voltage. In the inverter type X-ray high voltage apparatus comprising, the tube voltage digital feedback controller, the tube voltage detection signal and the inverter input voltage detection signal with an A / D converter for converting A / D, the A / D
An X-ray high-voltage device, wherein a part of processing required for X-ray control is performed in parallel during a conversion operation. 3. The X-ray high-voltage apparatus according to claim 1, wherein the tube voltage digital feedback control device includes a microcontroller having a built-in A / D converter.