Fluorescent x-ray analysis device and power supply device used therefor

Abstract

The invention relates to a fluorescent X-ray analysis device and a power supply device used for the fluorescent X-ray analysis device. An X-ray fluorescence analyzer is provided with an X-ray tube, a detector, a power supply device, and a control device. The X-ray tube includes a filament and a target, and irradiates a sample with primary X-rays. The detector detects secondary X-rays generated from the sample. The power supply device includes a high-voltage power supply unit that generates a tube voltage, a power supply wiring that transmits the tube voltage from the high-voltage power supply unit to a target, and a detection circuit. The detection circuit detects a voltage variation in a high-voltage circuit including an X-ray tube. The detection circuit includes a first resistive element having one end connected to a ground potential, a plurality of second resistive elements connected in series between the other end of the first resistive element and the feed wiring, a plurality of capacitors connected in parallel with each of the plurality of second resistive elements, and a high-pass filter connected to the other end of the first resistive element. The control device detects the occurrence of discharge in the high-voltage circuit on the basis of a signal from the detection circuit.

Description

Technical Field

[0001] The present disclosure relates to a fluorescent X-ray analysis device and a power supply device used for the fluorescent X-ray analysis device, and more particularly, to a discharge detection method in a power supply device used for the fluorescent X-ray analysis device. Background Art

[0002] Conventionally, fluorescent X-ray analyzers are known that irradiate a sample with X-rays and analyze the sample using fluorescent X-rays generated from the sample. Such X-ray analyzers utilize an X-ray generator, such as that disclosed in Japanese Patent Application Laid-Open No. 2010-212072. In an X-ray generator, X-rays are generated by applying a tube voltage to an X-ray tube equipped with a cathode electrode and a target electrode. Summary of the Invention

[0003] Problems to be solved by the invention

[0004] In X-ray generators, when a boosted high voltage is applied to an X-ray tube, unexpected discharges can sometimes occur in the high-voltage circuits that contain the X-ray tube. This discharge momentarily causes a current exceeding the normal operating range to flow through the circuit, potentially causing deterioration or failure of the power supply unit that applies the high voltage to the X-ray tube, or the X-ray tube itself.

[0005] To prevent degradation and failure caused by such discharges, X-ray generators are typically equipped with an overcurrent protection circuit to protect the circuits from the effects of overcurrent generated by such discharges. However, if a discharge occurs at a level undetectable by the overcurrent detection mechanism included in the overcurrent protection circuit, the device may continue to operate without the protection circuit providing protection. Furthermore, if intermittent discharges that are undetectable by the overcurrent detection mechanism occur, they can accelerate degradation of the power supply unit or X-ray tube, potentially leading to failure.

[0006] The overcurrent detection threshold used by the overcurrent detection mechanism can be lowered to improve detection sensitivity. However, if the threshold is lowered too much, there is a risk of malfunctioning of the protection circuit due to current fluctuations within the normal operating range. Another option is to increase the response speed of the overcurrent protection circuit, but this can increase the risk of malfunctioning due to load fluctuations or noise.

[0007] As another means of detecting the generation of overcurrent, it is also considered to indirectly detect overcurrent by detecting a drop in the output voltage of the high voltage during discharge. In this case, a differential circuit composed of a resistor and a capacitor is generally used to detect the voltage drop. However, in this case, the differential circuit needs to be connected to the high-voltage line, and the capacitor used in the differential circuit requires a capacitor with a high withstand voltage. Therefore, the component cost of the capacitor itself increases, and the installation fee and the cost of the molding material used for insulation may also increase. In addition, the device size of the power supply device also increases due to the addition of the capacitor.

[0008] The present disclosure has been made to solve such a problem, and an object of the present disclosure is to improve the accuracy of discharge detection while suppressing cost increases in an analysis device including an X-ray generator.

[0009] The first aspect of the present disclosure relates to a fluorescent X-ray analysis device comprising an X-ray tube, a detector, a power supply, and a control device. The X-ray tube includes a filament and a target for irradiating a sample with primary X-rays. The detector detects secondary X-rays generated from the sample. The power supply applies a tube voltage to the target. The control device detects the occurrence of discharge in the high-voltage circuit that includes the X-ray tube. The power supply includes: a high-voltage power supply unit that generates the tube voltage; a feeder line that transmits the tube voltage from the high-voltage power supply unit to the target; and a detection circuit connected to the feeder line. The detection circuit is configured to detect voltage fluctuations in the X-ray tube. The detection circuit includes: a first resistor element having one end connected to ground potential; a plurality of second resistor elements connected in series between the other end of the first resistor element and the feeder line; a plurality of capacitors connected in parallel with each of the second resistor elements; and a high-pass filter connected to the other end of the first resistor element. The control device detects the occurrence of discharge in the high-voltage circuit based on a signal from the detection circuit.

[0010] The power supply device according to the second aspect of the present disclosure applies a tube voltage to an X-ray tube including a filament and a target. The power supply device includes: a high-voltage power supply unit that generates the tube voltage; a feed wiring for transmitting the tube voltage from the high-voltage power supply unit to the target; and a detection circuit connected to the feed wiring. The detection circuit is configured to detect voltage fluctuations in a high-voltage circuit including the X-ray tube. The detection circuit includes: a first resistor element, one end of which is connected to a ground potential; a plurality of second resistor elements, the plurality of second resistor elements being connected in series between the other end of the first resistor element and the feed wiring; a plurality of capacitors, the plurality of capacitors being connected in parallel with the plurality of second resistor elements, respectively; a high-pass filter connected to the other end of the first resistor element; and a comparator, which is configured to compare a signal that has passed through the high-pass filter with a reference value.

[0011] The above objects, features, aspects and advantages and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 This is a diagram schematically showing a power supply device and an X-ray tube of the X-ray fluorescence analyzer according to the embodiment.

[0013] Figure 2 It shows Figure 1 Details of the detection circuit are shown in FIG.

[0014] Figure 3 yes Figure 1 Functional block diagram of the control device.

[0015] Figure 4 is a flowchart of the discharge detection process executed by the control device.

[0016] Figure 5 Is used to illustrate Figure 1 Diagram of the detection area of ​​the discharge voltage in the detection circuit.

[0017] Figure 6 It is a diagram showing details of a detection circuit according to Modification 1.

[0018] Figure 7 This is a diagram showing details of a detection circuit according to Modification 2. DETAILED DESCRIPTION

[0019] Next, refer to the attached Figure 1 In addition, the same or corresponding parts in the drawings are denoted by the same reference numerals, and their description will not be repeated.

[0020] [Implementation Method]

[0021] (Structure of Fluorescent X-ray Analyzer)

[0022] Figure 1 This figure schematically illustrates a fluorescent X-ray analyzer according to an embodiment. The fluorescent X-ray analyzer 10 is, for example, an energy dispersive X-ray fluorescent spectrometer (EDX). In this embodiment, an example in which a power supply device 100 for generating primary X-rays is employed in the fluorescent X-ray analyzer 10 will be described.

[0023] like Figure 1As shown, the fluorescent X-ray analysis device 10 includes a power supply device 100, an X-ray tube 200, a detector 300, and a control device 400. The power supply device 100 applies a voltage to the X-ray tube 200 to excite the primary X-ray B1. The primary X-ray B1 is irradiated to the sample S. The sample S irradiated with the primary X-ray B1 emits fluorescent X-rays B2. The fluorescent X-rays B2 emitted from the sample S are called "secondary X-rays" relative to the primary X-rays. The detector 300 detects the fluorescent X-rays B2. Thus, the fluorescent X-ray analysis device 10 can perform quantitative analysis and / or qualitative analysis of the sample S. In addition, Figure 1 , the control device 400 is described as an element independent of the power supply device 100 . However, all or part of the functions of the control device 400 may be included in the power supply device 100 or the high-voltage power supply unit 120 .

[0024] A target TG1 and a filament F1 are arranged inside the X-ray tube 200. The target TG1 serves as the anode, and the filament F1 serves as the cathode. Within the X-ray tube 200, the target TG1 and the filament F1 are spaced apart from each other. The power supply device 100 includes a filament power supply 110, a high-voltage power supply 120, a tube current control unit 130, overcurrent protection circuits 125 and 135, and a detection circuit 140.

[0025] The filament power supply 110 heats the filament F1 by supplying current to the filament F1. In the following description, the current supplied from the filament power supply 110 to the filament F1 is referred to as "filament current."

[0026] The high-voltage power supply 120 applies a high voltage to the target TG1 within the X-ray tube 200. In the following description, the high voltage applied by the high-voltage power supply 120 is referred to as "tube voltage." The high-voltage power supply 120 uses a rectifier, converter, Cockcroft-Walton circuit (none shown) and other components to boost the DC voltage converted from a commercial power source to generate a high voltage.

[0027] The high-voltage power supply 120 is connected to the target TG1 via a power line L4 and a resistor R4 provided on the power line L4. Furthermore, the high-voltage power supply 120 is connected to the ground potential GND via a power line L5 and a resistor R5. Within the X-ray tube 200, the heating of the filament F1 by the filament power supply 110 generates thermal electrons. These generated thermal electrons are driven toward the target TG1 by the tube voltage applied between the filament F1 and the target TG1 by the high-voltage power supply 120, ultimately impacting the target TG1. The impact of these thermal electrons generates primary X-rays B1.

[0028] The filament power supply 110 is connected to the filament F1 via power lines L1 and L2. Power line L1 is connected to terminal TF1 of the filament power supply 110 and terminal T1 of the power supply device 100. Power line L2 is connected to terminal TF2 of the filament power supply 110 and terminal T2 of the power supply device 100. Terminal T1 is connected to one end of the filament F1, and terminal T2 is connected to the other end of the filament F1.

[0029] Resistors R1 and R2 are connected in series between power lines L1 and L2. One end of power line L3 is connected to connection node NP1 between power lines L1 and L2. The other end of power line L3 is connected to ground potential GND via resistor R3. Alternatively, one end of power line L3 may be connected to either power line L1 or power line L2, rather than connection node NP1.

[0030] A protection circuit D1 including a Zener diode is connected between power line L1 and ground potential GND. Similarly, a protection circuit D2 including a Zener diode is connected between power line L2 and ground potential GND. Protection circuits D1 and D2 are circuits used to protect the filament power supply 110 and tube current control unit 130 from excessive current generated by discharge when discharge occurs in the X-ray tube 200.

[0031] The tube current control unit 130 performs feedback control on the output current from the filament power supply unit 110 based on the current flowing through the power line L3. More specifically, the tube current control unit 130 converts the tube current flowing through the power line L3 into a voltage value using a resistor R3 and detects the voltage. The tube current control unit 130 transmits the detected tube current value to the filament current control unit 111 and the overcurrent protection circuit 135.

[0032] The filament power supply 110 adjusts the filament current based on the tube current detected by the tube current control unit 130. The overcurrent protection circuit 135 is configured to determine whether an overcurrent condition exists based on a comparison between the current value detected by the tube current control unit 130 and a threshold value. If an overcurrent condition exists, the overcurrent protection circuit 135 stops the output of the high-voltage power supply 120.

[0033] Similarly, overcurrent protection circuit 125, located on the output side of high-voltage power supply 120, converts the current flowing through power line L5 into a voltage using resistor R5 and detects the voltage. If the overcurrent condition persists for a certain period, overcurrent protection circuit 125 stops the output of high-voltage power supply 120.

[0034] The detection circuit 140 is connected to the power line L4 and is configured to detect the voltage applied to the power line L4. Figure 2As described above, detection circuit 140 steps down the voltage applied to power line L4 using multiple resistors connected in series and detects fluctuations in the stepped-down voltage. Detection circuit 140 is connected to control device 400 at terminal T3 in power supply device 100. Control device 400 detects the occurrence of discharge in the high-voltage circuit that includes X-ray tube 200 based on the voltage fluctuations detected by detection circuit 140. Here, "high-voltage circuit" is a general term for circuits to which the high voltage output from high-voltage power supply 120 is applied, and includes not only X-ray tube 200 but also high-voltage power supply 120 and power line L4.

[0035] Equipment that includes an X-ray generator, such as fluorescent X-ray analyzers, is typically equipped with an overcurrent protection circuit, as described above, to protect the circuit from overcurrents caused by discharge. However, if discharge occurs at a level undetectable by the overcurrent detection mechanism included in the overcurrent protection circuit, the device may continue to be used without the protection circuit providing protection. Furthermore, if intermittent discharges that are undetectable by the overcurrent detection mechanism occur, this can lead to degradation and failure of the power supply or X-ray tube.

[0036] To detect such discharges, the overcurrent detection threshold used by the overcurrent detection mechanism can be lowered to improve detection sensitivity. However, if the threshold is lowered too much, there is a risk of false detection due to current fluctuations within the normal operating range, leading to malfunction of the protection circuit. Another option is to increase the response speed of the overcurrent protection circuit, but this increases the risk of malfunction due to load fluctuations or noise.

[0037] As another means for detecting the generation of overcurrent, it is also considered to detect overcurrent by detecting the drop in the output voltage of the high voltage during discharge. In this case, a differential circuit composed of a resistor and a capacitor is generally used to detect the voltage drop. However, in this case, it is necessary to connect the differential circuit to the high voltage line, but when such a circuit is separately added to the existing circuit, the capacitor used in the differential circuit needs to have a high withstand voltage. Therefore, the component cost of the capacitor itself increases, and the installation fee and the cost of the molding material for insulation may also increase. In addition, the device size of the power supply device also increases due to the addition of the capacitor.

[0038] Therefore, in the fluorescent X-ray analysis device 10 of this embodiment, in addition to the existing overcurrent protection circuit 125, a detection circuit 140 for detecting voltage fluctuations of the power line L4 on the output side of the high-voltage power supply unit 120 is provided. By providing this detection circuit 140, it is possible to detect abnormalities caused by output short circuits using the overcurrent protection circuit 125, and to detect instantaneous discharge using the detection circuit 140. In particular, in this embodiment, as will be described later, Figure 2 As described above, since the detection circuit 140 is constructed using the existing feedback circuit for controlling the voltage of the high-voltage power supply unit 120, the desired function can be achieved relatively cheaply with fewer additional components compared to the case where the detection circuit 140 is provided separately.

[0039] (Structure of detection circuit)

[0040] Figure 2 It shows Figure 1 Detailed diagram of the detection circuit 140. Figure 2 , the detection circuit 140 includes a resistor R10, RF1-RF10, a capacitor C10, CF1-CF10, a low-pass filter 141, a high-pass filter 142, an amplifier 143, a comparator (CMP) 144, a resistor R15, and an operational amplifier OP2. Figure 2 The capacitors denoted by CS1 to CS10 schematically represent parasitic capacitances generated between the resistors and the ground potential GND, and are not actually physical components.

[0041] Resistors RF1 to RF10 and resistor R10 are connected in series in this order between power line L4 and ground potential GND. Resistors RF1 to RF10 are used to step down the voltage applied to power line L4. Resistor R10 is used to divide the voltage at connection node N10 between resistors RF10 and R10.

[0042] The connection node N10 is connected to a terminal T3 for outputting to the detection circuit 140 via a low-pass filter 141 , a high-pass filter 142 , a resistor R15 , an operational amplifier OP2 , an amplifier 143 , and a comparator 144 .

[0043] In order to make the current flowing through the resistors RF1 to RF10 sufficiently small relative to the current flowing through the power line L4 to improve the efficiency of the high-voltage power supply unit 120, it is necessary to set the resistance value of each resistor RF1 to RF10 to a high resistance. As an example, if the resistance value of each resistor RF1 to RF10 is set to 200MΩ and the resistance value of the resistor R10 is set to 75kΩ, the high voltage of 5kV to 65kV applied to the power line L4 can be reduced to about several volts at the connection node N10. Figure 2 In the embodiment, a configuration using ten resistors as the voltage-dropping resistors RF1 to RF10 is exemplified. However, the number of resistors may be other than ten if the voltage can be dropped to a desired level.

[0044] Capacitors CF1 to CF10 are connected in parallel with resistors RF1 to RF10, respectively. Capacitor C10 is connected in parallel with resistor R10 between connection node N10 and ground potential GND.

[0045] Low-pass filter 141 includes a resistor R11, one end of which is connected to connection node N10, and a capacitor C11 connected between the other end of resistor R11 and ground potential GND. Low-pass filter 141 passes signals in a frequency band lower than the cutoff frequency determined by resistor R11 and capacitor C11. The signal passing through low-pass filter 141 is supplied to high-pass filter 142 and also used as feedback control signal FBK in high-voltage power supply unit 120.

[0046] High-pass filter 142 includes a capacitor C12 with one end connected to the other end of resistor R11 and a resistor R12 connected between the other end of capacitor C12 and ground GND. High-pass filter 142 passes signals in a frequency band higher than a cutoff frequency determined by resistor R12 and capacitor C12.

[0047] Operational amplifier OP2 is a voltage-follower operational amplifier. Its non-inverting input is connected to the other end of capacitor C12 in high-pass filter 142 via resistor R15. Its inverting input is connected to its output terminal. Operational amplifier OP2 functions as a buffer, isolating the circuit following amplifier 143. Resistor R15 is a protective resistor used to prevent excessive current from flowing through operational amplifier OP2.

[0048] When the high-pass filter 142 and the amplifier 143 are directly connected, the resistor R12 of the high-pass filter 142 and the resistor R13 of the amplifier 143 appear to be electrically connected in parallel. Therefore, the cutoff frequency of the high-pass filter 142 may not be the designed frequency due to the combined resistance formed by the resistors R12 and R13. Figure 2 In the circuit, the operational amplifier OP2 is disposed between the high-pass filter 142 and the amplifier 143 to electrically isolate the high-pass filter 142 from the amplifier 143. Furthermore, when the resistance values ​​of the resistors are designed in consideration of the above-described conditions, the operational amplifier OP2 may not necessarily be present.

[0049] Amplifier 143 includes an operational amplifier OP1 and resistors R13 and R14. One end of resistor R13 is connected to the output terminal of operational amplifier OP2, and the other end of resistor R13 is connected to one end of resistor R14. Furthermore, the other end of resistor R13 is also connected to the inverting input of operational amplifier OP1. The non-inverting input of operational amplifier OP1 is connected to ground potential GND, and the output terminal is connected to the other end of resistor R14. In other words, operational amplifier OP1 and resistors R13 and R14 form an inverting amplifier. The other end of resistor R14 is also connected to comparator 144.

[0050] Comparator 144 compares the signal that has passed through low-pass filter 141, high-pass filter 142, and amplifier 143 with a reference potential. For example, comparator 144 outputs a Hi (first state) signal when the signal is lower than the reference potential, and outputs a Lo (second state) signal when the signal is higher than the reference potential. Detection circuit 140 detects the occurrence of a discharge within the high-voltage circuit including X-ray tube 200 when the output signal from comparator 144 changes from Hi to Lo. Alternatively, the output signal of comparator 144 can be set to Lo when the input signal is lower than the reference potential, and to Hi when the input signal is higher than the reference potential.

[0051] (Discharge Detection Processing)

[0052] Next, use Figure 3 and Figure 4 The discharge detection process executed by control device 400 will be described. Figure 3 yes Figure 1 Functional block diagram of the control device 400. In addition, Figure 4 This is a flowchart for explaining the discharge detection process executed by control device 400 .

[0053] The control device 400 includes a counter circuit 410, a comparison circuit 420, and a notification circuit 430. The circuits included in the control device 400 are implemented by, for example, a programmable logic controller (PLD) and / or a central processing unit (CPU).

[0054] In step (hereinafter abbreviated as S) 100, the control device 400 uses the counter circuit 410 to count the number of times the output signal from the comparator 144 in the detection circuit 140 switches from Hi to Lo, that is, the number of times a discharge occurs in the high-voltage circuit including the X-ray tube 200. Then, in S110, the control device 400 compares the count value of the counter circuit 410 with a predetermined reference value using the comparison circuit 420 to determine whether the count value exceeds the reference value.

[0055] When the count value is below the reference value ("No" in S110), the control device 400 skips the subsequent processing while maintaining the count value. When the count value exceeds the reference value ("Yes" in S110), the control device 400 causes the processing to enter S120, determines that the discharge is abnormal, and outputs a signal to the notification circuit 430. The notification circuit 430 is composed of a display device capable of visual display such as a lamp or an LCD screen, or a buzzer or a device capable of sound output, and visually and / or auditorily notifies the user that a discharge has occurred more than a specified number of times (S130). In this way, the user can be aware of signs of abnormality and / or degradation of the X-ray generator.

[0056] Furthermore, the determination of discharge abnormality is not limited to the comparison between the count value and the reference value, and may be based on, for example, the change in the number of counts per hour. Specifically, a discharge abnormality may be determined when an increasing trend in the number of counts per hour is detected.

[0057] (Characteristics of the detection circuit)

[0058] When using Figure 2 When voltage is stepped down using resistors connected in series, such as resistors RF1 to RF10 in FIG. 1 , the resistors RF1 to RF10 and their parasitic capacitances CS1 to CS10 form a 10th-order low-pass filter connected in series. In this case, due to the time constant of the low-pass filter formed by the resistors and parasitic capacitances, the change in feedback signal FBK is delayed when the output of high-voltage power supply unit 120 fluctuates.

[0059] As a result, feedback control slows the response of high-voltage power supply 120 and detection circuit 140. Consequently, fluctuations in the output from high-voltage power supply 120 due to input and load fluctuations or noise can increase. This increases the intensity fluctuations of X-rays emitted by the X-ray tube, potentially affecting the stability of analytical results. Furthermore, if the response of high-voltage power supply 120 is slow, it takes longer to reach the desired output after changing the output voltage of high-voltage power supply 120, resulting in increased analysis time.

[0060] On the other hand, if discharge or an output short circuit occurs, the charge accumulated in the parasitic capacitance flows through resistors RF1-RF10 to power line L4. In this case, higher voltages are applied to resistors RF1-RF10 closer to power line L4, which can cause failure or degradation of these resistors. Since resistors RF1-RF10 affect the accuracy and stability of the output voltage of high-voltage power supply 120, failure or degradation of these resistors can also affect analysis accuracy.

[0061] In particular, the high-voltage portion of the power supply device 100 is generally sealed with a dielectric (molding material) having a dielectric constant higher than that of air to ensure a substantial isolation distance. Therefore, the parasitic capacitance generated by the molding material increases, and the impact caused by the above-mentioned problem tends to become significant.

[0062] To eliminate this problem, in the power supply device 100 of the embodiment, capacitors CF1 to CF10 are connected in parallel with resistors RF1 to RF10, respectively. If the capacitance of these parallel-connected capacitors CF1 to CF10 is sufficiently larger than that of parasitic capacitances CS1 to CS10, the effect of parasitic capacitances CS1 to CS10 can be negligible, and the high-frequency gain of voltage fluctuations can be increased. This can mitigate the effects of the aforementioned reduction in response speed and the effects of applying a high voltage to resistors RF1 to RF10 during discharge. For example, assuming that the maximum parasitic capacitance generated in each resistor is 10 pF, the effects of the parasitic capacitance can be mitigated by setting the capacitance of capacitors CF1 to CF10 to approximately 100 pF.

[0063] To improve the detection sensitivity of discharge, the reference potential set in the comparator 144 should be set as low as possible to detect small voltage fluctuations. On the other hand, it is necessary to prevent voltage fluctuations during normal operation of the X-ray generator from being erroneously detected as discharge.

[0064] The following two factors are considered as the main causes of voltage fluctuations during normal operation. The first is the voltage fluctuation caused by the voltage boosting operation during startup of the X-ray generator and intentional changes in the output voltage, such as by changing the output voltage setting of the high-voltage power supply 120. The second is voltage fluctuations caused by ripples associated with the switching operation of the voltage boosting power converter included in the high-voltage power supply 120.

[0065] In the detection circuit 140 of the embodiment, the voltage fluctuations associated with the above-described normal operation are separated by frequency using a low-pass filter 141 and a high-pass filter 142 to prevent false detection. In summary, intentional output voltage changes generally refer to voltage fluctuations that are gentler than those during discharge. Therefore, the effects of these voltage fluctuations are eliminated by the high-pass filter 142. Furthermore, the voltage fluctuations associated with pulsation depend on the switching frequency of the power conversion device and have a relatively high frequency compared to the voltage fluctuations during discharge. Therefore, the effects of these voltage fluctuations are eliminated by the low-pass filter 141.

[0066] For example, if the capacitance CCW of the Cockcroft-Walton circuit included in high-voltage power supply 120 is set to 144 pF, the capacitance of capacitors CF1 to CF10 is set to 100 pF, and the resistance of resistor R4 is set to 50 kΩ, the frequency of voltage fluctuation at the output end of high-voltage power supply 120 during discharge is approximately 21 kHz. Meanwhile, changes in the output voltage setting are gradual, approximately 16 Hz, and the frequency of the ripple voltage is, for example, approximately 60 kHz.

[0067] Therefore, for example, by setting the cutoff frequency of high-pass filter 142 to 1.6 kHz and the cutoff frequency of low-pass filter 141 to 30 kHz, it is possible to detect voltage fluctuations caused by discharge while eliminating the effects of voltage fluctuations associated with changes in output voltage settings and the effects of voltage fluctuations associated with pulsation. Furthermore, the cutoff frequency of low-pass filter 141 can be set to approximately 16 kHz, as long as it can eliminate the effects of pulsating voltage.

[0068] Figure 5 Is used to illustrate Figure 1 Diagram of the detection area of ​​the discharge voltage in the detection circuit. Figure 5 In FIG. 1 , the horizontal axis shows the frequency, and the vertical axis shows the voltage of the signal input to the comparator 144 . Figure 5 The line LN11 in FIG. 1 shows the bandpass characteristics of the low-pass filter 141 , and the line LN12 shows the bandpass characteristics of the high-pass filter 142 .

[0069] The cut-off frequency f1 of the high-pass filter 142 is lower than the cut-off frequency f2 of the low-pass filter 141 (f1 < f2). As Figure 5 such, a band-pass filter having a passband between f1 and f2 is formed by the low-pass filter 141 and the high-pass filter 142. That is, Figure 5 the region RG1 is a region where voltage fluctuations may occur along with changes in the output voltage, and the region RG2 is a region where voltage fluctuations may occur due to the pulsating voltage. As in the above example, by appropriately adjusting the cut-off frequencies f1 and f2 to set the region RG3 for discharge voltage detection, it is possible to detect voltage fluctuations caused by discharge while excluding the influence of voltage fluctuations caused by changes in the output voltage setting and the influence of voltage fluctuations caused by pulsation.

[0070] The "power line L4" in the embodiment corresponds to the "feed wiring" in the present disclosure. The "resistor R10" in the embodiment corresponds to the "first resistor element" in the present disclosure. Each of the resistors "resistors RF1 to RF10" in the embodiment corresponds to the "second resistor element" in the present disclosure.

[0071] <Modified Example 1>

[0072] Figure 6 is a diagram showing details of the detection circuit 140A of Modified Example 1. The detection circuit 140A has the following structure: Figure 2 the resistor R10 and the capacitor C10 in Figure 6 are respectively replaced with a resistor R10A and a capacitor C10A, and the amplifier 143 is deleted. In Figure 2 the description of elements that are not repeated with

[0073] Refer to Figure 6 , the capacitor C10A has a capacitance value smaller than that of the capacitor C10. In the case of discharge detection, since it is an instantaneous voltage change, or in other words, a high-frequency signal, the response (high-frequency gain) of the detection circuit to the high-frequency signal becomes important. In the case of a high-frequency signal, since voltage division is performed through the capacitor instead of the resistor, by making the capacitance value of the capacitor C10A smaller than the capacitance value of the capacitor C10, the potential at the connection node N10 becomes higher compared to the case of the detection circuit 140.

[0074] Therefore, by appropriately adjusting the capacitance value of the capacitor C10A, the amplifier 143 can be omitted. As a result, the number of components can be reduced, and thus cost reduction can be facilitated.

[0075] In the above example, the high frequency gain is improved by making the capacitance value of capacitor C10A smaller than that of capacitor C10 . However, the high frequency gain may be improved by increasing the capacitance values ​​of capacitors CF1 to CF10 .

[0076] <Variation 2>

[0077] Figure 7 140B is a diagram showing details of the detection circuit 140B of Modification 2. Figure 2 The structure of the low-pass filter 141 in FIG. Figure 7 In the process, do not repeat Figure 2 Description of the repeated element.

[0078] Figure 7 The structure can be applied to the case of a device in which the level of the ripple voltage in the boost circuit of the high-voltage power supply unit 120 is relatively small. In this case, it is also possible to contribute to cost reduction by reducing the number of components.

[0079] Furthermore, in the detection circuit 140B, the amplifier 143 can also be deleted by adjusting the capacitor C10 in the same manner as in the first modification.

[0080] High-pass filter 142 is provided to prevent erroneous detection during gentle changes in the output voltage from high-voltage power supply 120. However, in the discharge detection process of control device 400, high-pass filter 142 can be further omitted by, for example, blocking discharge detection during the period from activation of the X-ray generator until the voltage rises to a predetermined voltage, or blocking discharge detection during the voltage change period when the voltage setting value is changed.

[0081] [Note]

[0082] It will be understood by those skilled in the art that the above-mentioned multiple exemplary embodiments are specific examples of the following aspects.

[0083] (Item 1) One embodiment of a fluorescent X-ray analysis device includes an X-ray tube, a detector, a power supply, and a control device. The X-ray tube includes a filament and a target for irradiating a sample with primary X-rays. The detector detects secondary X-rays generated from the sample. The power supply applies a tube voltage to the target. The control device detects the occurrence of discharge in a high-voltage circuit including the X-ray tube. The power supply includes: a high-voltage power supply unit that generates the tube voltage; a feeder line that transmits the tube voltage from the high-voltage power supply unit to the target; and a detection circuit connected to the feeder line. The detection circuit is configured to detect voltage fluctuations in the X-ray tube. The detection circuit includes: a first resistor element having one end connected to ground potential; a plurality of second resistor elements connected in series between the other end of the first resistor element and the feeder line; a plurality of capacitors connected in parallel with each of the second resistor elements; and a high-pass filter connected to the other end of the first resistor element. The control device detects the occurrence of discharge in the high-voltage circuit based on a signal from the detection circuit.

[0084] According to the first aspect of the fluorescent X-ray analysis device, the tube voltage supplied from the high-voltage power supply to the X-ray tube is stepped down using a plurality of second resistor elements, each of which has a capacitor connected in parallel. The occurrence of discharge in the high-voltage circuit including the X-ray tube is detected based on the signal after high-pass filtering has been applied to the stepped-down signal. By stepping down the tube voltage using the second resistor elements connected in parallel with the capacitors, the influence of the low-pass filter formed by the second resistor elements and the parasitic capacitance is eliminated, thereby enabling high-response detection of voltage fluctuations in the tube voltage, i.e., the occurrence of discharge. Furthermore, by passing the stepped-down signal through the high-pass filter, it is possible to prevent erroneous detection of gentle voltage fluctuations that may occur during normal analysis operations as discharge. Relatively low-voltage components can be used for the components used in the detection circuit, thereby improving the accuracy of discharge detection while minimizing cost increases.

[0085] (Item 2) In the fluorescent X-ray analysis device described in Item 1, the detection circuit further includes an amplifier provided in a path connecting the other end of the first resistor element and the control device, for amplifying the signal passed through the high-pass filter.

[0086] According to the second aspect of the fluorescent X-ray analysis apparatus, the signal obtained by stepping down the tube voltage using the second resistor element is passed through a high-pass filter and then amplified by the amplifier. This increases the voltage level of the stepped-down signal, thereby enabling discharge detection even when voltage fluctuations are small.

[0087] (Item 3) In the fluorescent X-ray analysis device described in Item 1, the detection circuit further includes a low-pass filter provided in a path connecting the other end of the first resistor element to the control device and connected in series with the high-pass filter. The high-pass filter has a cutoff frequency lower than that of the low-pass filter.

[0088] The third aspect of the X-ray fluorescence analysis apparatus utilizes a low-pass filter with a higher cutoff frequency than the high-pass filter. This removes the effects of noise, such as ripple voltage generated in the high-voltage power supply unit, which has a higher frequency than discharge. This further improves the accuracy of discharge detection.

[0089] (Item 4) In the fluorescent X-ray analysis device described in Item 3, the detection circuit further includes an amplifier that amplifies the signal passed through the high-pass filter and the low-pass filter provided in the path connecting the other end of the first resistor element to the control device.

[0090] According to the fourth aspect of the fluorescent X-ray analysis apparatus, the signal obtained by reducing the tube voltage by the second resistor element is amplified by the amplifier after passing the signal through a high-pass filter and a low-pass filter. This increases the voltage level of the reduced signal, thereby enabling discharge detection even when voltage fluctuations are small.

[0091] (Item 5) In the fluorescent X-ray analysis device described in any one of Items 1 to 4, the detection circuit further includes a comparator configured to compare the signal passed through the high-pass filter with a reference value. The control device detects the occurrence of discharge in the high-voltage circuit based on an output signal from the comparator.

[0092] (Item 6) In the fluorescent X-ray analyzer described in Item 5, when the signal passed through the high-pass filter exceeds a reference value, the comparator changes the output signal from the first state to the second state. The control device determines that a discharge has occurred when the output signal from the comparator changes to the second state.

[0093] (Item 7) In the X-ray fluorescence analysis apparatus according to Item 6, when a predetermined number of discharges occur, the control device notifies the user.

[0094] According to the seventh aspect of the fluorescent X-ray analysis apparatus, by notifying the user when a predetermined number of discharges have occurred, the user can appropriately recognize a sign of abnormality or degradation of the X-ray generator.

[0095] (Item 8) A power supply device according to one embodiment applies a tube voltage to an X-ray tube including a filament and a target. The power supply device includes: a high-voltage power supply unit that generates the tube voltage; a feeder wiring for transmitting the tube voltage from the high-voltage power supply unit to the target; and a detection circuit connected to the feeder wiring. The detection circuit is configured to detect voltage fluctuations in a high-voltage circuit including the X-ray tube. The detection circuit includes: a first resistor element, one end of which is connected to a ground potential; a plurality of second resistor elements connected in series between the other end of the first resistor element and the feeder wiring; a plurality of capacitors connected in parallel to the plurality of second resistor elements, respectively; a high-pass filter connected to the other end of the first resistor element; and a comparator configured to compare a signal that has passed through the high-pass filter with a reference value.

[0096] (Item 9) One embodiment of a fluorescent X-ray analysis device includes an X-ray tube, a detector, a power supply, and a control device. The X-ray tube includes a filament and a target, and is used to irradiate a sample with primary X-rays. The detector detects secondary X-rays generated from the sample. The power supply applies a tube voltage to the target. The control device detects the occurrence of discharge in a high-voltage circuit including the X-ray tube. The power supply includes: a high-voltage power supply unit that generates the tube voltage; a feeder line that transmits the tube voltage from the high-voltage power supply unit to the target; and a detection circuit connected to the feeder line. The detection circuit is configured to detect voltage fluctuations in the high-voltage circuit. The detection circuit includes: a first resistor element having one end connected to ground potential; a plurality of second resistor elements connected in series between the other end of the first resistor element and the feeder line; and a plurality of capacitors connected in parallel with each of the second resistor elements. When the rate of change of a signal from the detection circuit exceeds a predetermined value, the control device detects the occurrence of discharge in the high-voltage circuit based on the signal from the detection circuit.

[0097] While the embodiments of the present invention have been described, the embodiments disclosed herein are to be considered in all respects as illustrative and non-restrictive. The scope of the present invention is indicated by the claims, and all modifications within the meaning and scope equivalent to the claims are intended to be included.

Claims

1. A fluorescent X-ray analysis device comprising: An X-ray tube comprising a filament and a target for irradiating primary X-rays to the sample; a detector that detects secondary X-rays generated from the sample; a power supply device for applying a tube voltage to the target; as well as a control device which detects the occurrence of an electric discharge in a high voltage circuit comprising the X-ray tube, in, The power supply device comprises: a high-voltage power supply unit for generating the tube voltage; a feed wiring for transmitting the tube voltage from the high-voltage power supply section to the target; and a detection circuit connected to the power feeding wiring and configured to detect voltage fluctuations in the high voltage circuit; Wherein, the detection circuit includes: a first resistance element, one end of which is connected to the ground potential; a plurality of second resistance elements connected in series between the other end of the first resistance element and the feed wiring; a plurality of capacitors connected in parallel to the plurality of second resistance elements, respectively; and a high-pass filter connected to the other end of the first resistance element, The control device detects occurrence of discharge in the high-voltage circuit based on a signal from the detection circuit.

2. The fluorescent X-ray analysis device according to claim 1, wherein The detection circuit further includes an amplifier provided in a path connecting the other end of the first resistor element and the control device, and configured to amplify the signal that has passed through the high-pass filter.

3. The fluorescent X-ray analysis device according to claim 1, wherein The detection circuit further includes a low-pass filter provided in a path connecting the other end of the first resistor element and the control device and connected in series with the high-pass filter. A cutoff frequency of the high-pass filter is lower than a cutoff frequency of the low-pass filter.

4. The fluorescent X-ray analysis device according to claim 3, wherein The detection circuit further includes an amplifier configured to amplify a signal that has passed through the high-pass filter and the low-pass filter provided in a path connecting the other end of the first resistance element and the control device.

5. The fluorescent X-ray analysis device according to claim 1, wherein The detection circuit further includes a comparator configured to compare the signal passed through the high-pass filter with a reference value. The control device detects occurrence of discharge in the high voltage circuit based on an output signal from the comparator.

6. The fluorescent X-ray analysis device according to claim 5, wherein When the signal passed through the high-pass filter exceeds the reference value, the comparator changes the output signal from the first state to the second state. The control device determines that discharge has occurred when the output signal from the comparator changes to the second state.

7. The fluorescent X-ray analysis device according to claim 6, wherein: The control device notifies a user when a predetermined number of discharges occur.

8. A power supply device for applying a tube voltage to an X-ray tube including a filament and a target, wherein: The power supply device comprises: a high-voltage power supply unit for generating the tube voltage; a feed wiring for transmitting the tube voltage from the high-voltage power supply section to the target; and a detection circuit connected to the power feeding wiring and configured to detect voltage fluctuations in a high voltage circuit including the X-ray tube; Wherein, the detection circuit includes: a first resistance element, one end of which is connected to the ground potential; a plurality of second resistance elements connected in series between the other end of the first resistance element and the feed wiring; a plurality of capacitors connected in parallel to the plurality of second resistance elements, respectively; a high-pass filter connected to the other end of the first resistance element; and The comparator is configured to compare the signal passed through the high-pass filter with a reference value.

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