X-ray fluorescence analyzer and power supply device

Abstract

The invention provides a fluorescent X-ray analyzer and a power supply device. The X-ray fluorescence analyzer includes a first power source that applies a tube voltage and a second power source that supplies a filament current. The first power supply has a switching circuit connected to the primary side of the transformer. This X-ray fluorescence analyzer is provided with: a current detection circuit that is connected to the primary side of a transformer and that detects a current flowing to the primary side of the transformer; and a control circuit that controls the first power supply based on the detected current. The current detection circuit includes a first comparator configured to be capable of detecting whether or not the current detected by the current detection circuit is equal to or greater than a first threshold value. The control circuit detects that discharge has occurred on the basis of the current detection circuit detecting a current equal to or greater than a first threshold value.

Description

Technical Field

[0001] The present disclosure relates to a fluorescence X-ray analysis apparatus and a power supply apparatus. Background Art

[0002] Conventionally, in a method of analyzing a sample by irradiating the sample with X-rays, an X-ray generating device has been used. Japanese Unexamined Patent Application Publication No. 2010-212072 (Patent Document 1) discloses an X-ray generating device in which X-rays are generated by applying a tube voltage to an X-ray tube having a cathode electrode and a target electrode disposed therein. In the X-ray generating device of Patent Document 1, when a high voltage boosted by a high-voltage power supply unit is applied to the X-ray tube, an accidental discharge sometimes occurs, for example, inside the X-ray tube. Summary of the Invention

[0003] The high-voltage power supply unit of the X-ray generating device in Patent Document 1 includes a DC-DC converter including a transformer for boosting the voltage. Sometimes, a mechanism for detecting an overcurrent is provided on the output side (secondary side of the transformer) of the high-voltage power supply unit to protect the high-voltage power supply unit from an overcurrent that causes a failure in the high-voltage power supply unit. Such an overcurrent that causes a failure in the high-voltage power supply unit may be generated due to a short circuit in the high-voltage power supply unit, in the X-ray tube, or in a high-voltage cable connecting the high-voltage power supply unit and the X-ray tube. Regarding the threshold value of the overcurrent detected by the overcurrent detection mechanism, it can be determined based on whether the current value is such that the generated X-rays leak to the outside due to the overcurrent. In addition, the overcurrent detection mechanism uses not only the current value but also the period during which the current flows to determine whether an overcurrent has occurred.

[0004] In a fluorescence X-ray analysis apparatus, a discharge that cannot be detected by the overcurrent detection mechanism sometimes occurs. That is, a discharge may occur in which either the magnitude of the current value or the period during which the current flows does not satisfy the threshold value of the overcurrent detection mechanism. The value of the current flowing through the high-voltage power supply unit due to a discharge that cannot be detected by the overcurrent detection mechanism is the same as the overcurrent that is the detection target of the overcurrent detection mechanism and is higher than the current value of the current flowing through the high-voltage power supply unit in a state where no abnormality occurs (normal state) in the fluorescence X-ray analysis apparatus. Even when such a discharge that cannot be detected by the overcurrent detection mechanism occurs, the high-voltage power supply unit can sometimes continue to operate without a failure. However, since such a discharge occurs intermittently, the high-voltage power supply unit sometimes deteriorates, resulting in a failure.

[0005] In an overcurrent detection mechanism provided on the output side of a high-voltage power supply unit, in order to suppress a transient voltage increase, it is possible to consider arranging a capacitor in parallel with a resistor for detecting current. However, when using the overcurrent detection mechanism to detect discharge, if a capacitor is arranged in parallel, the response speed decreases, and it becomes difficult to operate properly as a discharge detection mechanism.

[0006] The present disclosure has been made to solve the above problems, and an object thereof is to accurately detect the occurrence of discharge.

[0007] A fluorescence X-ray analysis apparatus according to one aspect of the present disclosure includes: an X-ray tube including a filament and a target for irradiating a specimen with primary X-rays; a detector for detecting secondary X-rays generated from the specimen; a first power supply for applying a tube voltage to the target; and a second power supply for supplying a filament current to the filament. The first power supply has a transformer and a switching circuit connected to the primary side of the transformer. The fluorescence X-ray analysis apparatus further includes: a current detection circuit connected to the primary side of the transformer for detecting a current flowing to the primary side of the transformer; and a control circuit for controlling the first power supply based on the current detected by the current detection circuit. The current detection circuit includes a first comparator configured to be able to detect whether the current detected by the current detection circuit is equal to or greater than a first threshold value. The control circuit detects the occurrence of discharge based on the fact that the current detected by the current detection circuit is equal to or greater than the first threshold value.

[0008] A power supply device according to an aspect of the present disclosure is a power supply device that supplies current to an X-ray tube including a filament and a target, and the power supply device includes: a first power supply for applying a tube voltage to the target; and a second power supply for supplying a filament current to the filament. The first power supply has a transformer and a switching circuit connected to the primary side of the transformer. The power supply device further includes: a current detection circuit connected to the primary side of the transformer for detecting a current flowing to the primary side of the transformer; and a control circuit for controlling the first power supply based on the current detected by the current detection circuit. The current detection circuit includes a first comparator configured to be able to detect whether the current detected by the current detection circuit is equal to or greater than a first threshold value. The control circuit detects the occurrence of discharge based on the fact that the current detected by the current detection circuit is equal to or greater than the first threshold value.

[0009] The above objects, features, aspects, and advantages of the present invention, as well as other objects, features, aspects, and advantages, will become clear from the following detailed description of the present invention that can be understood in association with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 FIG. schematically shows a power supply device of a fluorescence X-ray analysis apparatus and an X-ray tube.

[0011] Figure 2 This is a diagram for explaining the internal structure of the step-up DCDC converter 500 arranged within the high-voltage power supply unit in Embodiment 1.

[0012] Figure 3 This is a diagram for explaining the internal structure of the current detection circuit in Embodiment I.

[0013] Figure 4 This is a flowchart for explaining the discharge detection performed by the control circuit in Embodiment 1.

[0014] Figure 5 This is a diagram for explaining the internal structure of the current detection circuit in Embodiment 2.

[0015] Figure 6 This is a flowchart for explaining the discharge detection performed by the control circuit in Embodiment 2.

[0016] Figure 7 This is a flowchart for when the output voltage changes and is performed by the control circuit in Embodiment 2. Detailed Embodiment

[0017] [Embodiment 1]

[0018] This embodiment will be described in detail while referring to the accompanying drawings. In addition, for the same or corresponding parts in the drawings, the same reference numerals are assigned, and in principle, their descriptions will not be repeated.

[0019] <Structure of the Power Supply Device and the X-ray Tube>

[0020] Figure 1 This is a diagram schematically showing the power supply device 100 and the X-ray tube 200 of the fluorescent X-ray analysis device 1000. The fluorescent X-ray analysis device 1000 is, for example, an energy dispersive type fluorescent X-ray analysis device (EDX: Energy Dispersive X-ray Fluorescence Spectrometer). In this embodiment, an example of applying the power supply device 100 that generates primary X-rays in the fluorescent X-ray analysis device 1000 will be described.

[0021] As Figure 1As shown, the fluorescent X-ray analysis apparatus 1000 includes a power supply device 100, an X-ray tube 200, and a detector 300. The power supply device 100 applies a voltage to the X-ray tube 200 to excite primary X-rays 10. The primary X-rays 10 are irradiated onto the specimen S. The specimen S irradiated with the primary X-rays 10 emits fluorescent X-rays 20. The fluorescent X-rays 20 emitted from the specimen S are referred to as "secondary X-rays" with respect to the primary X-rays. The detector 300 detects the fluorescent X-rays 20. Thus, the fluorescent X-ray analysis apparatus 1000 can perform quantitative analysis or qualitative analysis of the specimen S.

[0022] Inside the X-ray tube 200, a target Tg1 and a filament F1 are disposed. The target Tg1 is an anode, and the filament F1 is a cathode. Inside the X-ray tube 200, the target Tg1 and the filament F1 are disposed at an interval from each other. The power supply device 100 includes a filament power supply unit 110, a high-voltage power supply unit 120, a tube current control unit 130, and overcurrent protection circuits 125, 135.

[0023] The filament power supply unit 110 heats the filament F1 by supplying current to the filament F1. Hereinafter, the current supplied from the filament power supply unit 110 to the filament F1 is referred to as "filament current".

[0024] The high-voltage power supply unit 120 applies a high voltage between the target Tg1 and the filament F1. Hereinafter, the high voltage applied by the high-voltage power supply unit 120 is referred to as "tube voltage". The high-voltage power supply unit 120 uses a rectifier, a converter, a Cockcroft-Walton circuit, etc. to boost the DC voltage converted from the commercial power supply by the switching power supply to generate a high voltage. In addition, the high-voltage power supply unit 120 can correspond to the "first power supply" of the present disclosure. In addition, the filament power supply unit 110 can correspond to the "second power supply" of the present disclosure.

[0025] As Figure 1 shown. The high-voltage power supply unit 120 is connected to the target Tg1 via the power line L3. In addition, the high-voltage power supply unit 120 is connected to the ground terminal GND via the power line L5. Inside the X-ray tube 200, by heating the filament F1 by the filament power supply unit 110, thermoelectrons are generated. By applying the tube voltage between the filament F1 and the target Tg1 by the high-voltage power supply unit 120, the thermoelectrons strike the target Tg1. Thus, the primary X-rays 10 are excited.

[0026] As Figure 1 shown, the filament power supply unit 110 is connected to the filament F1 via the power line L1 and the power line L1A. The power line L1 is connected to one end of the filament F1, and the power line L1A is connected to the other end of the filament F1. The terminals T1, T1A of the filament power supply unit 110 are respectively connected to the power lines L1, L1A. The terminals T2, T2A of the power supply device 100 are connected to the filament F1.

[0027] The connection point Cp1 is the connection point between the connection point between terminal T1 and terminal T2 and the connection point between terminal T1A and terminal T2A. A resistor R322 is connected between the connection point between terminal T1 and terminal T2 and the connection point Cp1. A resistor R316 is connected between the connection point between terminal T1A and terminal T2A and the connection point Cp1.

[0028] One end of the power line L4 is connected to the connection point Cp1, and the other end of the power line L4 is connected to the ground terminal GND via a resistor. In addition, one end of the power line L4 may be connected to the connection point between terminal T1 and terminal T2, or the connection point between terminal T1A and terminal T2A, instead of being connected to the connection point Cp1.

[0029] A protection circuit P1 including a Zener diode is connected between terminal T1 and terminal T2 in the power line L1. Similarly, a protection circuit P1A including a Zener diode is connected between terminal T1A and terminal T2A in the power line L1A. The protection circuits P1 and P1A are circuits for protecting the filament power supply unit 110 and the tube current control unit 130 from the influence of discharges generated in the X-ray tube 200.

[0030] The tube current control unit 130 performs feedback control to adjust the output of the filament power supply unit 110 based on the current value flowing in the power line L4. More specifically, the tube current control unit 130 converts the tube current flowing through the power line L4 into a voltage value using a resistor and amplifies it through an amplifier Am1, thereby detecting the tube current value of the tube current flowing in the power line L4. The tube current control unit 130 sends the detected tube current value to the filament current control unit 111 and the overcurrent protection circuit 135.

[0031] The filament power supply unit 110 adjusts the output filament current based on the tube current value detected by the tube current control unit 130. The overcurrent protection circuit 135 detects whether the current value detected by the tube current control unit 130 is an overcurrent. Specifically, the overcurrent protection circuit 135 is configured to stop the output of the high-voltage power supply unit 120 when the current value detected by the tube current control unit 130 differs from the desired tube current value by a specified value.

[0032] Similarly, the overcurrent protection circuit 125 disposed on the output side of the high-voltage power supply unit 120 converts the current flowing through the power line L5 into a voltage value using a resistor and amplifies it through an amplifier Am2 to detect the current flowing in the power line L5. The overcurrent protection circuit 125 is a circuit that stops the output of the high-voltage power supply unit 120 when an overcurrent is detected to flow continuously for a certain period to protect the high-voltage power supply unit 120 from the influence of the overcurrent.

[0033] Thus, in the fluorescent X-ray analysis apparatus 1000 according to the present embodiment, when an overcurrent is detected by the overcurrent protection circuits 125 and 135 disposed on the output side of the high-voltage power supply unit 120, the high-voltage power supply unit 120 stops outputting. In other words, in the fluorescent X-ray analysis apparatus 1000 according to the present embodiment, when an overcurrent is detected, the high-voltage power supply unit 120 stops operating to protect the high-voltage power supply unit 120, the resistors connected to the power lines L3 and L4, and the resistors R316, R322, etc. from the influence of the overcurrent.

[0034] The cause of the overcurrent having a current value that can cause a failure in the high-voltage power supply unit 120 may be due to a short circuit occurring in the high-voltage power supply unit 120, in the X-ray tube 200, or in the power line L3 connecting the high-voltage power supply unit 120 and the X-ray tube 200. The overcurrent detection mechanism uses both the magnitude of the current value and the period during which the current flows to determine whether an overcurrent has occurred. However, since a discharge occurs in which either the magnitude of the current value or the period during which the current flows does not satisfy the threshold value set for the overcurrent detection mechanism, a discharge of a level that cannot be detected by the overcurrent detection mechanism occurs. Such a discharge cannot be detected by the overcurrent detection mechanism, and on the other hand, it is higher than the current value of the current flowing during normal operation when no abnormality occurs in the fluorescent X-ray analysis apparatus 1000.

[0035] Even when such a discharge occurs, the high-voltage power supply unit 120 can sometimes operate without a failure. However, since the discharge occurs intermittently multiple times, the high-voltage power supply unit 120 may deteriorate or even fail. In addition, the reliability of the data detected by the detector 300 in a state where the discharge occurs intermittently is lower than the reliability of the data detected in a state where no discharge occurs.

[0036] In the overcurrent protection circuit 125 disposed on the output side of the high-voltage power supply unit 120, in order to suppress a transient voltage increase, it is considered to dispose a capacitor in parallel with the resistor for detecting the current. However, when the overcurrent protection circuit 125 is used to detect a discharge, if a capacitor is disposed in parallel, the response speed decreases, and it is difficult for the overcurrent protection circuit 125 to operate properly as a mechanism for detecting a discharge. Even in a case where a method for improving the response speed of the overcurrent protection circuit 125 and suppressing a transient voltage increase is assumed, the possibility of the overcurrent protection circuit 125 malfunctioning increases due to the increase in the response speed of the overcurrent protection circuit 125, and the manufacturing cost of the power supply device 100 increases.

[0037] When a discharge occurs inside the X-ray tube 200 or the like, the voltage of the power line L3 on the output side of the high-voltage power supply unit 120 decreases. Therefore, in the present embodiment, it is considered to newly provide an output voltage monitor or a differential circuit for detecting the output voltage of the high-voltage power supply unit 120 on the output side of the high-voltage power supply unit 120, and to detect the discharge by detecting the voltage drop. Thus, the fluorescence X-ray analysis apparatus 1000 can detect the discharge without using the overcurrent protection circuits 125 and 135.

[0038] However, even when an output voltage monitor is newly provided on the output side of the high-voltage power supply unit 120, it is necessary to provide an AD converter with a high sampling speed, and the manufacturing cost of the power supply device 100 increases. In addition, even when a differential circuit is provided, it is necessary to provide a high withstand voltage capacitor in the differential circuit. Therefore, similarly to the case of providing an output voltage monitor, the manufacturing cost of the power supply device 100 increases. Further, since the high withstand voltage capacitor required in the case of providing a differential circuit is to be provided on the output side of the high-voltage power supply unit 120, the size of the power supply device 100 becomes large.

[0039] Therefore, in the fluorescence X-ray analysis apparatus 1000 of the present embodiment, a current detection circuit included in the high-voltage power supply unit 120 for detecting the current in the step-up DCDC converter inside the high-voltage power supply unit 120 is used to detect a discharge that generates a current having a current value higher than the current flowing in the high-voltage power supply unit 120 in a state where no abnormality occurs in the fluorescence X-ray analysis apparatus 1000. Hereinafter, Figure 2 、 Figure 3 is used to describe the DCDC converter and the current detection circuit in Embodiment 1.

[0040] Figure 2 is a diagram for explaining the internal structure of the step-up DCDC converter 500 disposed inside the high-voltage power supply unit 120 in Embodiment 1. Figure 1 The high-voltage power supply unit 120 in Figure 2 has the DCDC converter 500 shown in Figure 1 The power supply device 100 in Figure 2 has the drive circuit 350 shown in

[0041] As shown in Figure 2As shown, the DCDC converter 500 includes a transformer 30, a primary side circuit 401 of the transformer, and a secondary side circuit 402 of the transformer. The transformer 30 includes primary windings Tr11 and Tr12 included in the primary side circuit 401 of the transformer, and a secondary winding Tr2 included in the secondary side circuit 402 of the transformer. In addition, the transformer 30 can correspond to the "transformer" of the present disclosure.

[0042] By driving the switching elements Mf1 and Mf2, the DCDC converter 500 boosts the DC voltage of 24V applied from the power supply voltage VCC. The DC voltage applied from the power supply voltage VCC is generated by rectifying a commercial power supply or the like. In addition, the DC voltage applied from the power supply voltage VCC can also be a voltage other than 24V. The voltage boosted by the DCDC converter 500 is further boosted to the output voltage of the high-voltage power supply unit 120 by a Cockcroft-Walton circuit or the like. The output voltage of the high-voltage power supply unit 120 is, for example, 60 kV.

[0043] As Figure 2 shown, in the primary side circuit 401 of the transformer, the power supply voltage VCC is connected to the primary windings Tr11 and Tr12, respectively. An inductor L10 is connected between the power supply voltage VCC and the primary windings Tr11 and Tr12. Capacitors C5, C6, and C7 are connected in parallel between one end of the inductor L10 and the ground terminal GND. In addition, capacitors C8 to C12 are connected in parallel between the other end of the inductor L10 and the ground terminal GND. The capacitors C5 to C12 function as bypass capacitors for removing AC components. In addition, in some aspects, the capacitors C5 to C7 may be composed of a number of capacitors other than three, for example, a single capacitor. Similarly, the capacitors C8 to C12 may be composed of a number of capacitors other than five, for example, a single capacitor.

[0044] As Figure 2 shown, an inductor L10 is connected to one end of the primary winding Tr11. The drain terminal of the switching element Mf1 is connected to the other end of the primary winding Tr11. In Embodiment 1, the switching element Mf1 is, for example, a MOSFET (Metal Oxide Semiconductor Field Effect Transistor), and is an element for switching the current supply to the primary winding Tr11. A buffer circuit Sn1 is connected between the drain terminal and the source terminal of the switching element Mf1. The buffer circuit Sn1 is a protection circuit for suppressing the transient high voltage generated when the switching element Mf1 is switched off.

[0045] The gate terminal of the switching element Mf1 is connected to the drive circuit 350 via the resistor R2. The drive circuit 350 performs PWM (Pulse Width Modulation) control on the switching element Mf1. A resistor R4 and a bidirectional Zener diode D1 are connected in parallel between the gate terminal and the source terminal of the switching element Mf1. The bidirectional Zener diode D1 is provided to protect the switching element Mf1 when an overvoltage occurs at the gate terminal of the switching element Mf1.

[0046] Similarly, the circuit connected to the primary winding Tr12 will also be described. An inductor L10 is connected to one end of the primary winding Tr12, and a switching element Mf2 is connected to the other end of the primary winding Tr12. Similar to the switching element Mf1, the switching element Mf2 is, for example, a MOSFET. A snubber circuit Sn2 is connected between the drain terminal and the source terminal of the switching element Mf2. The snubber circuit Sn2 is a protection circuit for suppressing the transient high voltage generated when the switching element Mf2 is switched off.

[0047] The gate terminal of the switching element Mf2 is connected to the drive circuit 350 via the resistor R6. The drive circuit 350 performs PWM control on the switching element Mf2. A resistor R8 and a bidirectional Zener diode D2 are connected in parallel between the gate terminal and the source terminal of the switching element Mf2. The bidirectional Zener diode D2 is provided to protect the switching element Mf2 when an overvoltage occurs at the gate terminal of the switching element Mf2.

[0048] The drive circuit 350 repeats the on-state and the off-state of the switching element Mf1 and repeats the on-state and the off-state of the switching element Mf2 to alternately supply current to the primary winding Tr11 and the primary winding Tr12. The drive circuit 350 controls each switching element Mf1, Mf2 so that the switching elements Mf1, Mf2 do not simultaneously become in the on-state. In one aspect, the switching elements Mf1, Mf2 may also be IGBTs (Insulated Gate Bipolar Transistors) instead of MOSFETs. In addition, the switching elements Mf1, Mf2 can each correspond to the "switching circuit" of the present disclosure.

[0049] Next, the current detection circuit 600 will be described. As Figure 2As shown, the source terminals of the switching elements Mf1 and Mf2 are respectively connected to one ends of the resistors R10 and R11. The other ends of the resistors R10 and R11 are connected to the ground terminal GND. In addition, one ends of the resistors R10 and R11 are connected to the terminal DET1 of the current detection circuit 600 via the resistor R9, and the other ends of the resistors R10 and R11 are connected to the terminal DET2 via the resistor R12.

[0050] In this way, by connecting the voltages at both ends of the resistors R10 and R11 to the current detection circuit 600, the current detection circuit 600 can detect the current value of the current flowing through the switching element Mf1 or the switching element Mf2 for each pulse of the switching element. As Figure 2 shown, a capacitor C17 is connected between the resistor R9 and the resistor R12. The capacitor C17 is arranged to remove the noise of the AC component.

[0051] In addition, as Figure 2 shown, in the secondary side circuit 402 of the transformer connected to the target Tg1, the secondary winding Tr2 is connected to the capacitor C100. The capacitor C100 is, for example, a smoothing capacitor or a capacitor used in a Cockcroft-Walton circuit. In the present embodiment, when a discharge occurs, for example, inside the X-ray tube 200, the output voltage of the high-voltage power supply unit 120 decreases due to this discharge. Along with this, the high-voltage power supply unit 120 raises the decreased output voltage through feedback control. At this time, it is necessary to charge the capacitor C100 in the secondary side circuit 402 of the transformer.

[0052] Since the capacitor C100 is charged, a current larger than the current flowing through the switching element Mf1 or the switching element Mf2 in the state where no abnormal discharge occurs and the tube voltage is applied will flow. In order to suppress the large current flowing through the switching elements Mf1 and Mf2 due to the charging of the capacitor C100, the current detection circuit 600 uses a comparator described later to detect the situation where a current larger than the normal current value when no abnormal discharge occurs is generated, and temporarily stops the operation of the high-voltage power supply unit 120.

[0053] The current detection circuit 600 inside the high-voltage power supply unit 120 is a circuit that detects whether a current larger than the normal current value when no abnormality occurs flows through the switching elements Mf1 and Mf2. In the present embodiment, this current detection circuit 600 is used to detect the discharge.

[0054] Figure 3This is a diagram for explaining the internal structure of the current detection circuit 600 in Embodiment 1. The current detection circuit 600 in Embodiment 1 uses an amplifier to amplify the voltage value obtained by converting the detected current using a resistor pair. The comparator Cmp1 is a comparator for determining whether the current value detected by the current detection circuit 600 is equal to or greater than a first threshold value. In other words, the comparator Cmp1 obtains the voltage value amplified by the operational amplifiers M1091 and M1092 and sends an output result indicating whether the current value detected by the current detection circuit 600 is equal to or greater than the first threshold value to the control circuit 400. The first threshold value is, for example, 30 A. In addition, as long as the first threshold value can be used to detect discharge, it can also be other current values, such as 28 A or 32 A. The current detection circuit 600 of Embodiment 1 includes two-stage operational amplifiers M1091 and M1092 and a comparator Cmp1. In some aspects, the current detection circuit 600 may also include a single-stage operational amplifier instead of two-stage operational amplifiers, or the operational amplifier itself may not be provided. In addition, the comparator Cmp1 can correspond to the "first comparator" of the present disclosure.

[0055] As Figure 3 shown, the terminal DET1 is connected to the inverting input terminal of the operational amplifier M1091 via the resistor RM1. The terminal DET2 is connected to the non-inverting input terminal of the operational amplifier M1091 via the resistor RM2. One ends of the capacitors C148, C147, and the resistor RM22 are connected between the resistor RM2 and the non-inverting input terminal of the operational amplifier M1091. The other ends of the capacitors C147, C148, and the resistor RM22 are connected to the ground terminal GND. The capacitors C147 and C148 function as bypass capacitors.

[0056] And, as Figure 3 shown, the capacitors C137, C140, and the resistor RM11 are connected in parallel between the output terminal and the inverting input terminal of the operational amplifier M1091. The capacitors C137 and C140 are arranged to remove high-frequency noise.

[0057] As Figure 3 shown, the output terminal of the operational amplifier M1091 is connected to the non-inverting input terminal of the operational amplifier M1092. The inverting input terminal of the operational amplifier M1092 is connected to the ground terminal GND via the resistor R153. Additionally, as Figure 3As shown, a capacitor C139 and a resistor R154 are connected in parallel between the output terminal and the inverting input terminal of the operational amplifier M1092. Similar to the capacitors C137 and C140, the capacitor C139 is arranged to remove high-frequency noise. In this way, in Embodiment 1, two-stage operational amplifiers M1091 and M1092 are used to amplify the detected current.

[0058] The output terminal of the operational amplifier M1092 is connected to the inverting input terminal of the comparator Cmp1 via the resistor R156. One end of a capacitor C145 and the cathode of a Zener diode D104 are connected between the resistor R156 and the inverting input terminal of the comparator Cmp1. The other end of the capacitor C145 and the anode of the Zener diode D104 are respectively connected to the ground terminal GND.

[0059] The non-inverting input terminal of the comparator Cmp1 is connected to the power supply voltage 2.5V via the resistors R161 and R162. The first threshold value varies according to the value of the power supply voltage 2.5V, the resistance values of the resistors R161, R162, R165, and R167, etc. One end of a capacitor C142 and one end of a resistor R165 are connected between the resistor R162 and the non-inverting input terminal of the comparator Cmp1. The other end of the resistor R165 is connected to the ground terminal GND via the resistor R167. The other end of the capacitor C142 is connected to the ground terminal GND. The capacitor C142 functions as a bypass capacitor.

[0060] The output terminal of the comparator Cmp1 is connected to the power supply voltage 3.3V via the resistor R155. When the current detected by the current detection circuit 600 is equal to or greater than the first threshold value, the comparator Cmp1 outputs a low level from the output terminal. On the other hand, when the current value detected by the current detection circuit 600 is less than the first threshold value, the comparator Cmp1 outputs a high level from the output terminal. The control circuit 400 receives the output result of the comparator Cmp1 and performs processing according to the received output result.

[0061] In Embodiment 1, the control circuit 400 is a PLD (Programmable Logic Device). In some aspects, the control circuit 400 can also be a processor such as a CPU (Central Processing Unit), an MPU (Micro-Processing Unit), or a GPU (Graphics Processing Unit). Such a processor has the function of performing various processes by executing a program, but part or all of the functions of the processor can also be an integrated circuit for specific purposes such as an FPGA (Field Programmable Gate Array) or an ASIC (Application Specific Integrated Circuit).

[0062] The term "processor" is not limited to a narrow sense of a processor that executes processes in a stored-program manner such as a CPU or an MPU, and can include, for example, a hardwired circuit such as an ASIC or an FPGA. Therefore, a processor can also be replaced with a processing circuitry that has a process predefined by computer-readable code and / or a hardwired circuit. In addition, a processor can be composed of one chip or multiple chips.

[0063] Moreover, the processor and associated processing circuitry can also be composed of multiple computers connected to each other in a wired or wireless manner via a local area network or a wireless network. The processor and associated processing circuitry can also be composed of a cloud computer that performs operations remotely based on input data and outputs the operation results to other devices at a separate location.

[0064] Figure 4 It is a flowchart for explaining the discharge detection performed by the control circuit 400 in Embodiment 1. During the period when the high-voltage power supply unit 120 is driven, the control circuit 400 repeatedly executes Figure 4 the flowchart of.

[0065] The control circuit 400 determines whether a current equal to or greater than the first threshold is detected based on the output result of the comparator Cmp1 (step S110). If a current equal to or greater than the first threshold is not detected (No in step S110), the control circuit 400 ends the process. On the other hand, if a current equal to or greater than the first threshold is detected (Yes in step S110), the control circuit 400 causes the drive circuit 350 to stop applying the PWM signal (step S120). As a result, the output from the high-voltage power supply unit 120 stops.

[0066] Thereafter, the control circuit 400 performs a discharge process (step S130). The discharge process in Embodiment 1 is a process performed when it is detected that a current larger than that in the normal state including discharge is generated. Specifically, in step S130, the control circuit 400 notifies the user that a current larger than that in the normal state including discharge is generated. The control circuit 400 notifies the user of the occurrence of discharge, for example, using a display device, a speaker, a transmitter, etc. provided in the fluorescent X-ray analysis device 1000. Alternatively, the discharge process may be a process of storing the date and time when a current larger than that in the normal state including discharge is generated, without notifying the user that a current larger than that in the normal state including discharge is generated.

[0067] In this way, in Embodiment 1, the current detection circuit 600 included in the high-voltage power supply unit 120 can be used to detect discharge with high precision. When the power supply device 100 in Embodiment 1 detects discharge, it stops the operation of the high-voltage power supply unit 120.

[0068] [Embodiment 2]

[0069] In Embodiment 1, the structure in which the current detection circuit 600 has one comparator Cmp1 has been described. In Embodiment 1, the discharge process is performed when a current equal to or higher than the first threshold (30 A) is detected. However, in Embodiment 1, a discharge smaller than the first threshold (30 A) cannot be detected.

[0070] In Embodiment 2, a fluorescent X-ray analysis device 1000 having a structure that is more likely to detect a discharge that does not cause a failure in the high-voltage power supply unit 120 will be described. In Embodiment 2, the structures that are the same as those of the fluorescent X-ray analysis device 1000 in Embodiment 1 will not be repeatedly described.

[0071] Figure 5 is a diagram for explaining the internal structure of the current detection circuit 600A in Embodiment 2. As Figure 5 shown, the current detection circuit 600A in Embodiment 2 has, in addition to the comparator Cmp1, a comparator Cmp2. In Embodiment 2, the output terminal of the operational amplifier M1092 is connected to the inverting input terminals of the comparator Cmp1 and the comparator Cmp2 via the resistor R156. In addition, the comparator Cmp2 can correspond to the "second comparator" of the present disclosure.

[0072] Comparator Cmp2, like comparator Cmp1, obtains the voltage values amplified by operational amplifiers M1091 and M1092, and sends the output result indicating whether the current value detected by the current detection circuit 600 is equal to or higher than the second threshold to the control circuit 400. The non-inverting input terminal of comparator Cmp2 is connected to the power supply voltage of 2.5V via resistor R1. The voltage value of the non-inverting input terminal of comparator Cmp1 is different from the voltage value of the non-inverting input terminal of comparator Cmp2. That is, the first threshold as the comparison object of comparator Cmp1 and the second threshold as the comparison object of comparator Cmp2 are different values. The second threshold is a value lower than the first threshold, for example, 25A. The second threshold is the threshold for detecting discharges that generate relatively low current values. That is, comparator Cmp2 is a comparator that can detect discharges with lower current values than the discharges that can be detected in Embodiment 1.

[0073] As Figure 5 shown, one end of capacitor C1 and one end of resistor R2 are connected between resistor R1 and the non-inverting input terminal of comparator Cmp2. The other end of capacitor C1 and the other end of resistor R2 are connected to the ground terminal GND. Capacitor C1 functions as a bypass capacitor.

[0074] The output terminal of comparator Cmp2 is connected to the power supply voltage of 3.3V via resistor R3. When the current value detected by the current detection circuit 600A is equal to or higher than the second threshold, a low level is output from the output terminal of comparator Cmp2. In addition, comparator Cmp2 is configured to output a high level when the current value detected by the current detection circuit 600A is less than the second threshold. The control circuit 400 receives the output result of comparator Cmp2 and performs processing based on the received output result.

[0075] Figure 6 is a flowchart for explaining the discharge detection performed by the control circuit 400 in Embodiment 2. During the period when the high-voltage power supply unit 120 is driven, the control circuit 400 of Embodiment 2 repeatedly executes Figure 6 the flowchart.

[0076] The control circuit 400 determines whether a current equal to or higher than the second threshold is detected based on the output result of comparator Cmp2 (step S210). When a current equal to or higher than the second threshold is not detected ( "No" in step S210), the control circuit 400 ends the processing.

[0077] When a current equal to or greater than the second threshold is detected (Yes in step S210), the control circuit 400 determines whether a current equal to or greater than the first threshold is detected based on the output result of the comparator Cmp1 (step S220). When a current equal to or greater than the first threshold is not detected in step S220 (No in step S220), the control circuit 400 performs a discharge process (step S230). In the second embodiment, as in the first embodiment, the discharge process is also a process of notifying the user that a discharge has occurred, but it may also be the following process: storing the date and time when a discharge occurred, such as inside the X-ray tube 200, without notifying the user that a discharge has occurred.

[0078] Return to step S220. When a current equal to or greater than the first threshold is detected (Yes in step S220), the control circuit 400 causes the drive circuit 350 to stop applying the PWM signal (step S240). After that, the control circuit 400 performs a discharge process (step S250).

[0079] In this way, in the second embodiment, it is possible to detect separately an overcurrent that causes a failure of the high-voltage power supply unit 120 and a discharge with a relatively small current. As a result, it is possible to stop applying the PWM signal only when there is a high possibility that an overcurrent that causes a failure of the high-voltage power supply unit 120 has occurred. In the second embodiment, as in the first embodiment, it is possible to use the current detection circuit 600 included in the high-voltage power supply unit 120 to detect a discharge. That is, the fluorescence X-ray analysis apparatus 1000 according to the second embodiment can also detect the occurrence of a discharge with high accuracy.

[0080] As described above, when a discharge occurs, the voltage on the output side of the high-voltage power supply unit 120 decreases. As the output-side voltage decreases, the control circuit 400 raises the decreased output voltage through feedback control. At this time, the capacitor C100 is charged, and a large current temporarily flows in the transformer primary-side circuit 401. However, even when the user changes the set value of the output voltage of the high-voltage power supply unit 120, since the capacitor C100 is charged again, a large current temporarily flows in the transformer primary-side circuit 401.

[0081] That is, when the user changes the set value of the output voltage of the high-voltage power supply unit 120, the control circuit 400 may erroneously detect that a discharge has occurred. Therefore, in the second embodiment, the control circuit 400 executes the following flowchart so as not to determine that a discharge has occurred when the set value of the output voltage of the high-voltage power supply unit 120 is changed, thereby suppressing false detection of a discharge.

[0082] Figure 7This is the flowchart when the output voltage is changed, which is executed by the control circuit 400 in Embodiment 2. During the period when the high-voltage power supply unit 120 is driven, in addition to executing the flowchart of Figure 6 , the control circuit 400 of Embodiment 2 repeatedly executes the flowchart of Figure 7 . The control circuit 400 determines whether the set value of the output voltage of the high-voltage power supply unit 120 has been changed (step S310). For example, the control circuit 400 receives from the outside a signal indicating that the set value of the output voltage of the high-voltage power supply unit 120 has been changed.

[0083] When the set value of the output voltage has not been changed ( "No" in step S310), the control circuit 400 ends the process. When the set value of the output voltage has been changed ( "Yes" in step S310), the control circuit 400 determines whether a first period has elapsed since the set value of the output voltage was changed (step S320). When the first period has not elapsed ( "No" in step S320), the control circuit 400 ignores the output results of the comparator Cmp1 and the comparator Cmp2 (step S330). In other words, in step S330, even when the detection result of the comparator Cmp1 indicates that a current equal to or higher than the first threshold has been detected, or the detection result of the comparator Cmp2 indicates that a current equal to or higher than the second threshold has been detected, the control circuit 400 determines that no discharge has occurred.

[0084] After that, the control circuit 400 returns the process to step S320. That is, during the period from when the set value of the output voltage is changed until the first period elapses, the control circuit 400 continuously ignores the output result of the comparator Cmp2. In other words, even when the comparator Cmp2 detects a current value equal to or higher than the second threshold, the control circuit 400 does not determine that a discharge has occurred. The first period can be, for example, values such as 10 ms, 100 ms, 1000 ms, etc. The value of the first period changes according to the change content of the set value of the output voltage. When the first period has elapsed ( "Yes" in step S320), the control circuit 400 ends the process. Thus, in the fluorescence X-ray analysis apparatus 1000 of Embodiment 2, it is possible to prevent a false detection of a discharge when the set value of the output voltage of the high-voltage power supply unit 120 has been changed. Of course, Figure 7 The flowchart when the output voltage is changed shown can also be applied to Embodiment 1 having only one comparator.

[0085] <Variant Example>

[0086] In the example of Embodiment 1, it was described that the control circuit 400 notifies the user of an abnormality such as discharge or short circuit after detecting a current flowing above a first threshold. However, the control circuit 400 may not immediately notify the user after detecting a current flowing above the first threshold. For example, the control circuit 400 may also notify the user of an abnormality such as discharge or short circuit based on the occurrence of a prescribed number of discharges within a prescribed period, in order to prompt the user to perform maintenance on the fluorescence X-ray analysis apparatus 1000. Thereby, in the fluorescence X-ray analysis apparatus 1000, it is possible to notify the user at an appropriate timing when degradation has occurred in the X-ray tube 200, such as when discharges frequently occur. The prescribed period is, for example, 1 hour, and the prescribed number of times is, for example, 50 times.

[0087] Furthermore, in the example of Embodiment 2, the following configuration was described: the control circuit 400 determines in step S210 whether a current at a second threshold is detected, and then determines in step S220 whether a current at the first threshold is detected. However, the order of detecting a current at or above the second threshold and detecting a current at or above the first threshold may be reversed, and the control circuit 400 may also perform the detection of a current at or above the second threshold and the detection of a current at or above the first threshold in parallel.

[0088] Furthermore, in Embodiment 2, an example was described in which, after the control circuit 400 receives a setting change of the output voltage value from the outside, the control circuit 400 ignores the detection result of the comparator Cmp2. However, the power supply device 100 may further include a control board superior to the control circuit 400, and it may be determined by this superior control board whether to perform a discharge process based on the detection result of the comparator Cmp2 input from the control circuit 400. In this case, the superior control board may also ignore a command to perform a discharge process from the control circuit 400 for a certain period from when the setting change is received from the user.

[0089] [Embodiment]

[0090] Those skilled in the art can understand that the above-described multiple exemplary embodiments are specific examples of the following embodiments.

[0091] (First item)

[0092] A fluorescence X-ray analysis apparatus (1000) according to one embodiment includes:

[0093] An X-ray tube (200) including a filament (F1) and a target (Tg1), for irradiating a specimen (S) with primary X-rays (10);

[0094] A detector (300) for detecting secondary X-rays (20) generated from the specimen;

[0095] A first power supply (120) that applies a tube voltage to the target; and

[0096] A second power supply (110) that supplies a filament current to the filament,

[0097] wherein the first power supply includes:

[0098] A transformer (30); and

[0099] A switching circuit (Mf1, Mf2) connected to the primary side of the transformer,

[0100] The fluorescent X-ray analysis device further includes:

[0101] A current detection circuit (600) connected to the primary side of the transformer for detecting the current flowing to the primary side of the transformer; and

[0102] A control circuit (400) that controls the first power supply based on the current detected by the current detection circuit,

[0103] wherein the current detection circuit includes a first comparator configured to be able to detect whether the current detected by the current detection circuit is equal to or greater than the first threshold value,

[0104] The control circuit detects the occurrence of a discharge based on the current detected by the current detection circuit being equal to or greater than the first threshold value.

[0105] According to the fluorescent X-ray analysis device 1000 described in the first item, the occurrence of a discharge can be detected with high accuracy.

[0106] (Second item) In the fluorescent X-ray analysis device (1000) described in the first item,

[0107] The current detection circuit (600A) further includes a second comparator (Cmp2) that can detect whether the current detected by the current detection circuit is equal to or greater than a second threshold value lower than the first threshold value.

[0108] According to the fluorescent X-ray analysis device 1000 described in the second item, control actions can be changed using multiple threshold values.

[0109] (Third item) In the fluorescent X-ray analysis device (1000) described in the second item,

[0110] When the current detected by the current detection circuit is equal to or greater than the second threshold value and equal to or greater than the first threshold value, the control circuit stops the operation of the first power supply,

[0111] When the current detected by the current detection circuit is equal to or greater than the second threshold and less than the first threshold, the control circuit does not stop the operation of the first power supply.

[0112] According to the fluorescence X-ray analysis apparatus 1000 described in the third aspect, when a discharge exceeding a first threshold set for preventing damage to the circuit is detected, the application of the PWM signal can be temporarily stopped. On the other hand, when a discharge exceeding a second threshold smaller than the first threshold is detected, only the discharge process is performed. Thus, by setting the second threshold to a value greater than the current value during normal operation and smaller than the first threshold, the discharge can be detected with higher accuracy.

[0113] (Fourth aspect) In the fluorescence X-ray analysis apparatus (1000) described in the third aspect,

[0114] During the period from when the change of the set value of the output voltage of the first power supply is accepted until a first period elapses, the control circuit determines that no such discharge has occurred even if the current detected by the current detection circuit is equal to or greater than the second threshold.

[0115] According to the fluorescence X-ray analysis apparatus 1000 described in the fourth aspect, false detection of a discharge occurring due to a change in the set value of the output voltage can be suppressed.

[0116] (Fifth aspect) In the fluorescence X-ray analysis apparatus (1000) according to any one of the first to fourth aspects,

[0117] When the control circuit determines that the discharge has occurred a specified number of times (e.g., 100 times) within a specified period (e.g., 1 hour), the user is urged to perform maintenance on the fluorescence X-ray analysis apparatus.

[0118] According to the fluorescence X-ray analysis apparatus 1000 described in the fifth aspect, the user can be urged to perform maintenance on the fluorescence X-ray analysis apparatus based on the frequency of the discharge that has occurred.

[0119] (Sixth aspect) In the fluorescence X-ray analysis apparatus (1000) described in the first aspect,

[0120] During the period from when the change of the set value of the output voltage of the first power supply is accepted until a first period elapses, the control circuit determines that no such discharge has occurred even if the current detected by the current detection circuit is equal to or greater than the first threshold.

[0121] According to the fluorescence X-ray analysis apparatus 1000 described in the sixth aspect, false detection of a discharge occurring due to a change in the set value of the output voltage can be suppressed.

[0122] (Item 7) A power supply device (100) involved in one way supplies current to an X-ray tube (200) including a filament (F1) and a target (Tg1), and the power supply device (100) includes:

[0123] A first power supply (120) that applies a tube voltage to the target; and

[0124] A second power supply (110) that supplies a filament current to the filament,

[0125] wherein the first power supply has:

[0126] A transformer (30); and

[0127] A switching circuit (Mf1, Mf2) connected to the primary side of the transformer,

[0128] The power supply device (100) further includes:

[0129] A current detection circuit (600) connected to the primary side of the transformer for detecting the current flowing to the primary side of the transformer; and

[0130] A control circuit (400) that controls the first power supply based on the current detected by the current detection circuit,

[0131] wherein the current detection circuit includes a first comparator configured to be able to detect whether the current detected by the current detection circuit is equal to or greater than the first threshold,

[0132] The control circuit detects the occurrence of a discharge based on the fact that the current detected by the current detection circuit is equal to or greater than the first threshold.

[0133] According to the power supply device 100 described in Item 7, the occurrence of a discharge can be detected with high accuracy.

[0134] The embodiments of the present invention have been described, but it should be considered that the embodiments disclosed this time are examples in all aspects and not restrictive. The scope of the present invention is shown by the claims and is intended to include all modifications within the same meaning and scope as the claims.

Claims

1. A fluorescent X-ray analysis device, comprising: An X-ray tube, comprising a filament and a target, for irradiating a sample with primary X-rays; a detector that detects secondary X-rays generated from the sample; a first power supply for applying a tube voltage to the target; as well as a second power supply that supplies a filament current to the filament, Wherein, the first power supply comprises: Transformers; and a switching circuit connected to the primary side of the transformer, The fluorescent X-ray analysis device further comprises: a current detection circuit connected to the primary side of the transformer and configured to detect a current flowing to the primary side of the transformer; and a control circuit that controls the first power supply based on the current detected by the current detection circuit, The current detection circuit includes a first comparator, and the first comparator is configured to detect whether the current detected by the current detection circuit is greater than a first threshold value. The control circuit detects that discharge has occurred based on the current detection circuit detecting a current equal to or greater than the first threshold value.

2. The fluorescent X-ray analysis device according to claim 1, wherein: The current detection circuit further includes a second comparator capable of detecting whether the current detected by the current detection circuit is equal to or higher than a second threshold value lower than the first threshold value.

3. The fluorescent X-ray analysis device according to claim 2, wherein: When the current detected by the current detection circuit is greater than or equal to the second threshold value and greater than or equal to the first threshold value, the control circuit stops the operation of the first power supply. When the current detected by the current detection circuit is equal to or greater than the second threshold value and less than the first threshold value, the control circuit does not stop the operation of the first power supply.

4. The fluorescent X-ray analysis device according to claim 3, wherein: The control circuit determines that the discharge has not occurred during a period from when a change in the set value of the output voltage of the first power supply is accepted until a first period has elapsed, even if the current detected by the current detection circuit is equal to or greater than the second threshold.

5. The fluorescent X-ray analysis device according to any one of claims 1 to 4, wherein: The control circuit prompts a user to perform maintenance of the X-ray fluorescence analysis device when determining that the discharge has occurred a predetermined number of times within a predetermined period.

6. The fluorescent X-ray analysis device according to claim 1, wherein: The control circuit determines that the discharge has not occurred during a period from when a change in the set value of the output voltage of the first power supply is accepted until a first period has elapsed, even if the current detected by the current detection circuit is equal to or greater than the first threshold.

7. A power supply device for supplying current to an X-ray tube including a filament and a target, the power supply device comprising: a first power supply that applies a tube voltage to the target; and a second power supply that supplies a filament current to the filament, in, The first power supply has: Transformers; and a switching circuit connected to the primary side of the transformer, The power supply device further comprises: a current detection circuit connected to the primary side of the transformer and used to detect the current flowing to the primary side of the transformer; as well as a control circuit that controls the first power supply based on the current detected by the current detection circuit, The current detection circuit includes a first comparator, and the first comparator is configured to detect whether the current detected by the current detection circuit is greater than a first threshold value. The control circuit detects that discharge has occurred based on the current detection circuit detecting a current equal to or greater than the first threshold value.

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