Fluorescent x-ray analysis device, and power supply device

Abstract

To accurately detect generation of electric discharge.SOLUTION: A fluorescent x-ray analysis device includes: a first power supply for applying a tube voltage; and a second power supply for supplying a filament current. The first power supply has a switching circuit connected to the primary side of a transformer. The fluorescent x-ray analysis device includes: a current detection circuit connected to the primary side of the transformer to detect a current that flows to the primary side of the transformer; and a control circuit for controlling the first power supply on the basis of the detected current. The current detection circuit includes a first comparator configured to detect whether or not the current detected by the current detection circuit is a first threshold value or more. The control circuit detects generation of electric discharge on the basis of the detection of the current of the first threshold value or more by the current detection circuit.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present disclosure relates to a fluorescent X-ray analyzer and a power supply device.

Background Art

[0002] Conventionally, in a method of irradiating a sample with X-rays for analysis of the sample, an X-ray generator has been used. Patent Document 1 (Japanese Patent Application Laid-Open No. 2010-212072) discloses an X-ray generator that generates X-rays by applying a tube voltage to an X-ray tube in which a cathode electrode and a target electrode are arranged. In the X-ray generator of Patent Document 1, when the high voltage after being boosted by the high-voltage power supply unit is applied to the X-ray tube, for example, an unintentional discharge may occur inside the X-ray tube.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The high-voltage power supply unit of the X-ray generator in Patent Document 1 has a DC-DC converter including a transformer for boosting the voltage. On the output side of this high-voltage power supply unit (the secondary side of the transformer), a mechanism for detecting an overcurrent may be provided to protect the high-voltage power supply unit from an overcurrent at a level where the high-voltage power supply unit fails. Such an overcurrent at a level where the high-voltage power supply unit fails can occur due to a short circuit in the high-voltage power supply unit, inside the X-ray tube, or in the high-voltage cable connecting the high-voltage power supply unit and the X-ray tube. The threshold value of the overcurrent detected by the overcurrent detection mechanism can be determined based on whether the current value of the X-rays generated by the overcurrent leaks to the outside. In addition to the current value, the overcurrent detection mechanism determines the presence or absence of the occurrence of an overcurrent using the period during which the current flows.

[0005] In a fluorescent X-ray analyzer, there may be a discharge at a level that cannot be detected by the overcurrent detection mechanism. That is, a discharge may occur in which either the magnitude of the current value or the period during which the current flows is less than the threshold of the overcurrent detection mechanism. The value of the current flowing through the high-voltage power supply unit due to such a discharge at a level that cannot be detected by the overcurrent detection mechanism is higher than the current value flowing through the high-voltage power supply unit in a state where no abnormality has occurred in the fluorescent X-ray analyzer (normal state), similar to the overcurrent that is the detection target of the overcurrent detection mechanism. The high-voltage power supply unit may be able to continue operating without failure even when such a discharge at a level that cannot be detected by the overcurrent detector occurs, but due to such intermittent discharges, the high-voltage power supply unit may deteriorate and eventually lead to a failure.

[0006] In the overcurrent detection mechanism provided on the output side of the high-voltage power supply unit, in order to suppress a transient voltage increase, it is conceivable to arrange a capacitor in parallel with the resistor for current detection. However, when detecting a discharge using the overcurrent detection mechanism, arranging a capacitor in parallel will reduce the response speed and make it difficult to operate properly as a discharge detection mechanism.

[0007] The present disclosure has been made to solve the above problems, and its object is to accurately detect the occurrence of a discharge.

Means for Solving the Problems

[0008] A fluorescence X-ray analyzer according to one aspect of the present disclosure includes an X-ray tube that includes a filament and a target and irradiates a sample with primary X-rays, a detector that detects secondary X-rays generated from the sample, a first power source that applies a tube voltage to the target, and a second power source that supplies a filament current to the filament. The first power source includes a transformer and a switching circuit connected to the primary side of the transformer. The fluorescence X-ray analyzer further includes a current detection circuit that is connected to the primary side of the transformer and detects a current flowing through the primary side of the transformer, and a control circuit that controls the first power source 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 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 a discharge has occurred based on the fact that a current equal to or greater than the first threshold value has been detected by the current detection circuit.

[0009] 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 includes a first power source that applies a tube voltage to the target and a second power source that supplies a filament current to the filament. The first power source includes a transformer and a switching circuit connected to the primary side of the transformer. The power supply device further includes a current detection circuit that is connected to the primary side of the transformer and detects a current flowing through the primary side of the transformer, and a control circuit that controls the first power source 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 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 a discharge has occurred based on the fact that a current equal to or greater than the first threshold value has been detected by the current detection circuit.

Advantages of the Invention

[0010] According to the present disclosure, the occurrence of a discharge can be accurately detected.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

[0012] [Embodiment 1] This embodiment will be described in detail with reference to the drawings. For the same or corresponding parts in the drawings, the same reference numerals are given, and the description thereof will not be repeated in principle.

[0013] <Configuration of Power Supply Device and X-ray Tube FIG. 1 is a diagram schematically showing a power supply device 100 and an X-ray tube 200 of a fluorescence X-ray analyzer 1000. The fluorescence X-ray analyzer 1000 is, for example, an energy dispersive fluorescence X-ray analyzer (EDX: Energy Dispersive X-ray Fluorescence Spectrometer). In this embodiment, an example in which a power supply device 100 that generates primary X-rays is applied to the fluorescence X-ray analyzer 1000 will be described.

[0014] As shown in FIG. 1, the X-ray fluorescence analyzer 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 the primary X-ray 10. The primary X-ray 10 is irradiated onto the sample S. The sample S irradiated with the primary X-ray 10 emits fluorescence X-ray 20. The fluorescence X-ray 20 emitted from the sample S is referred to as "secondary X-ray" with respect to the primary X-ray. The detector 300 detects the fluorescence X-ray 20. Thereby, the X-ray fluorescence analyzer 1000 can perform quantitative analysis or qualitative analysis of the sample S.

[0015] Inside the X-ray tube 200, a target Tg1 and a filament F1 are arranged. The target Tg1 is an anode, and the filament F1 is a cathode. In the X-ray tube 200, the target Tg1 and the filament F1 are arranged at intervals 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 and 135.

[0016] 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".

[0017] 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 using a switching power supply to generate a high voltage. Note that the high voltage power supply unit 120 may correspond to the "first power supply" in the present disclosure. Also, the filament power supply unit 110 may correspond to the "second power supply" in the present disclosure.

[0018] As shown in FIG. 1, the high-voltage power supply unit 120 is connected to the target Tg1 via the power line L3. Also, 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, thermoelectrons are generated by heating the filament F1 by the filament power supply unit 110. The thermoelectrons collide with the target Tg1 when a tube voltage is applied between the filament F1 and the target Tg1 by the high-voltage power supply unit 120. Thereby, the primary X-ray 10 is excited.

[0019] As shown in FIG. 1, 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 and T1A of the filament power supply unit 110 are connected to the power lines L1 and L1A, respectively. The terminals T2 and T2A of the power supply device 100 are connected to the filament F1.

[0020] The connection point Cp1 is the connection point between the connection point of the terminals T1 and T2 and the connection point of the terminals T1A and T2A. A resistor R322 is connected between the connection point Cp1 and the connection point of the terminals T1 and T2. A resistor R316 is connected between the connection point Cp1 and the connection point of the terminals T1A and T2A.

[0021] 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. Note that one end of the power line L4 may be connected to either the connection point of the terminals T1 and T2 or the connection point of the terminals T1A and T2A instead of the connection point Cp1.

[0022] A protection circuit P1 including a Zener diode is connected between a terminal T1 and a terminal T2 on a power line L1. Similarly, a protection circuit P1A including a Zener diode is connected between a terminal T1A and a terminal T2A on a power line L1A. The protection circuits P1 and P1A are circuits for protecting a filament power supply unit 110 and a tube current control unit 130 from discharges generated within an X-ray tube 200.

[0023] 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 of the current flowing through a power line L4. More specifically, the tube current control unit 130 detects the tube current value flowing through the power line L4 by converting the tube current flowing through the power line L4 into a voltage value with a resistor and amplifying it with an amplifier Am1. The tube current control unit 130 transmits the detected tube current value to a filament current control unit 111 and an overcurrent protection circuit 135.

[0024] The filament power supply unit 110 adjusts the filament current output 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, when there is a deviation of the current detected by the tube current control unit 130 by a predetermined value from a desired tube current value, the overcurrent protection circuit 135 is configured to stop the output of the high-voltage power supply unit 120.

[0025] Similarly, an overcurrent protection circuit 125 arranged on the output side of the high-voltage power supply unit 120 converts the current flowing through a power line L5 into a voltage value with a resistor and amplifies it with an amplifier Am2 to detect the current flowing through the power line L5. The overcurrent protection circuit 125 is a circuit that stops the output of the high-voltage power supply unit 120 to protect the high-voltage power supply unit 120 from overcurrents when it detects that an overcurrent has flowed continuously for a certain period.

[0026] Thus, in the fluorescent X-ray analyzer 1000 according to this embodiment, when an overcurrent is detected by the overcurrent protection circuits 125 and 135 arranged on the output side of the high-voltage power supply unit 120, the output of the high-voltage power supply unit 120 is stopped. In other words, in the fluorescent X-ray analyzer 1000 according to this embodiment, when an overcurrent is detected, the operation of the high-voltage power supply unit 120 is stopped to protect the high-voltage power supply unit 120, the resistors connected to the power lines L3 and L4, and the resistors R316 and R322 from the overcurrent.

[0027] The occurrence of an overcurrent having a current value at a level that causes 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 determines whether an overcurrent is occurring by using both the magnitude of the current value and the period during which the current flows. However, a discharge that does not meet the threshold value set in the overcurrent detection mechanism occurs either in terms of the magnitude of the current value or the period during which the current flows, resulting in a discharge at a level that cannot be detected by the overcurrent detection mechanism. Such a discharge cannot be detected by the overcurrent detection mechanism, but is higher than the current value flowing during normal operation when no abnormality occurs in the fluorescent X-ray analyzer 1000.

[0028] The high-voltage power supply unit 120 may be able to operate without failure even when such a discharge occurs, but the high-voltage power supply unit 120 may deteriorate or fail due to the discharge occurring intermittently multiple times. Also, the reliability of the data detected by the detector 300 in a state where the discharge is occurring intermittently is lower than the reliability of the data detected in a state where no discharge is occurring.

[0029] In the overcurrent protection circuit 125 provided on the output side of the high-voltage power supply unit 120, in order to suppress a transient voltage increase, it is conceivable to arrange a capacitor in parallel with the resistor for current detection. However, when detecting discharge using the overcurrent protection circuit 125, if a capacitor is arranged in parallel, the response speed will decrease, and it will be difficult for the overcurrent protection circuit 125 to operate properly as a mechanism for discharge detection. Even if a method for suppressing a transient voltage increase is adopted while increasing the response speed of the overcurrent protection circuit 125, the probability of malfunction of the overcurrent protection circuit 125 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 will increase.

[0030] When 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 conceivable 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 detect discharge by detecting the voltage drop. Thereby, the fluorescence X-ray analyzer 1000 can detect discharge without using the overcurrent protection circuits 125 and 135.

[0031] However, even when newly providing an output voltage monitor on the output side of the high-voltage power supply unit 120, it is necessary to install an AD converter with a high sampling speed, and the manufacturing cost of the power supply device 100 increases. Also, even when providing a differential circuit, since it is necessary to provide a high withstand voltage capacitor in the differential circuit, the manufacturing cost of the power supply device 100 increases in the same way as when providing an output voltage monitor. In addition, since the high withstand voltage capacitor required when providing a differential circuit will be installed on the output side of the high-voltage power supply unit 120, the size of the power supply device 100 will increase.

[0032] Therefore, in the X-ray fluorescence analyzer 1000 of the present embodiment, a current detection circuit that detects the current in the step-up DCDC converter inside the high-voltage power supply unit 120 is used, and a current detection circuit included in the high-voltage power supply unit 120 is used to detect a discharge that generates a current higher than the current value flowing in the high-voltage power supply unit 120 in a state where no abnormality has occurred in the X-ray fluorescence analyzer 1000. Hereinafter, the DCDC converter and the current detection circuit in Embodiment 1 will be described with reference to FIGS. 2 and 3.

[0033] FIG. 2 is a diagram for explaining the internal configuration of the step-up DCDC converter 500 disposed in the high-voltage power supply unit 120 in Embodiment 1. The high-voltage power supply unit 120 in FIG. 1 includes the DCDC converter 500 shown in FIG. 2. The power supply device 100 in FIG. 1 includes a drive circuit 350 shown in FIG. 2 and a current detection circuit 600 that detects the current in the primary side circuit of the transformer. The DCDC converter 500 in Embodiment 1 is a DCDC converter, and more specifically, a push-pull converter.

[0034] As shown in FIG. 2, 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. Note that the transformer 30 may correspond to the "transformer" in the present disclosure.

[0035] The DCDC converter 500 boosts the DC voltage of 24V applied from the power supply voltage VCC by driving the switching elements Mf1 and Mf2. The DC voltage applied from the power supply voltage VCC is generated by rectifying a commercial power supply or the like. Note that the DC voltage applied from the power supply voltage VCC may 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.

[0036] As shown in FIG. 2, in the transformer primary-side circuit 401, the power supply voltage VCC is connected to each of the primary windings Tr11 and Tr12. 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. Also, 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 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 also be composed of a number of capacitors other than five, for example, a single capacitor.

[0037] As shown in FIG. 2, 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 supply of current to the primary winding Tr11. A snubber circuit Sn1 is connected between the drain terminal of the switching element Mf1 and the source terminal of the switching element Mf1. The snubber circuit Sn1 is a protection circuit for suppressing the transient high voltage generated when the switch in the switching element Mf1 is turned off.

[0038] A drive circuit 350 is connected to the gate terminal of the switching element Mf1 via a 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 of the switching element Mf1 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.

[0039] 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. The switching element Mf2 is, for example, a MOSFET, similar to the switching element Mf1. 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 that suppresses the transient high voltage generated when the switch of the switching element Mf2 is turned off.

[0040] A drive circuit 350 is connected to the gate terminal of the switching element Mf2 via a 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 of the switching element Mf2 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.

[0041] The drive circuit 350 repeatedly turns on and off the switching element Mf1 and repeatedly turns on and off the switching element Mf2, and alternately supplies current to the primary winding Tr11 and the primary winding Tr12. The drive circuit 350 controls each of the switching elements Mf1 and Mf2 so that the switching elements Mf1 and Mf2 do not simultaneously turn on. In a certain aspect, the switching elements Mf1 and Mf2 may be IGBTs (Insulated Gate Bipolar Transistors) instead of MOSFETs. Each of the switching elements Mf1 and Mf2 may correspond to the "switching circuit" in the present disclosure.

[0042] Next, the current detection circuit 600 will be described. As shown in FIG. 2, one end of each of the resistors R10 and R11 is connected to the source terminals of the switching elements Mf1 and Mf2, respectively. The other ends of the resistors R10 and R11 are connected to the ground terminal GND. Also, one end of the resistors R10 and R11 is connected to the terminal DET1 of the current detection circuit 600 via the resistor R9, and the other end of the resistors R10 and R11 is connected to the terminal DET2 via the resistor R12.

[0043] Thus, by connecting the voltages across both ends of the resistor R10 and the resistor R11 to the current detection circuit 600, the current detection circuit 600 can detect the current value flowing through the switching element Mf1 or the switching element Mf2 for each switching pulse. As shown in FIG. 2, a capacitor C17 is connected between the resistor R9 and the resistor R12. The capacitor C17 is arranged for the purpose of removing AC component noise.

[0044] Also, as shown in FIG. 2, in the secondary circuit 402 of the transformer connected to the target Tg1, a capacitor C100 is connected to the secondary winding Tr2. 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 the discharge. Along with this, the high-voltage power supply unit 120 raises the decreased output voltage by feedback control. At this time, it is necessary to charge the capacitor C100 in the secondary circuit 402 of the transformer.

[0045] To charge the capacitor C100, a current larger than the current flowing in a state where no abnormality such as a discharge has occurred and the tube voltage is applied flows through the switching element Mf1 or the switching element Mf2. The current detection circuit 600 uses a comparator described later to detect that a current larger than the normal current value when no abnormality such as a discharge has occurred is generated in order to suppress a large current from flowing through the switching elements Mf1 and Mf2 due to the charging of the capacitor C100, and stops the operation of the high-voltage power supply unit 120 once.

[0046] The current detection circuit 600 inside the high-voltage power supply 120 is a circuit that detects whether a current larger than the normal current value when no abnormality has occurred flows through the switching elements Mf1 and Mf2. In the present embodiment, this current detection circuit 600 is used for detecting a discharge.

[0047] FIG. 3 is a diagram for explaining the internal configuration 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 with a resistor. 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 the first threshold value. In other words, the comparator Cmp1 obtains the voltage value amplified by the operational amplifiers M1091 and M1092, and transmits 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. Note that the first threshold value may be another current value as long as discharge can be detected, and may be, for example, 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. However, in some aspects, the current detection circuit 600 may have a single-stage operational amplifier instead of two stages, or may not have an operational amplifier itself. Note that the comparator Cmp1 may correspond to the "first comparator" in the present disclosure.

[0048] As shown in FIG. 3, 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 end of the capacitor C148, the capacitor C147, and the resistor RM22 is connected between the resistor RM2 and the non-inverting input terminal of the operational amplifier M1091. The other ends of the capacitors C147 and C148 and the resistor RM22 are connected to the ground terminal GND. The capacitors C147 and C148 function as bypass capacitors.

[0049] Furthermore, as shown in FIG. 3, a capacitor C137, a capacitor C140, and a resistor RM11 are connected in parallel between the output terminal of the operational amplifier M1091 and the inverting input terminal of the operational amplifier M1091. The capacitors C137 and C140 are arranged for the purpose of removing high-frequency noise.

[0050] As shown in FIG. 3, 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. Also, as shown in FIG. 3, between the output terminal of the operational amplifier M1092 and the inverting input terminal of the operational amplifier M1092, the capacitors C139 and the resistor R154 are connected in parallel. The capacitor C139 is arranged for the purpose of removing high-frequency noise, similar to the capacitors C137 and C140. Thus, in Embodiment 1, the detected current is amplified using the two-stage operational amplifiers M1091 and M1092.

[0051] 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 the capacitor C145 and the cathode of the Zener diode D104 are connected between the resistor R156 and the inverting input terminal of the comparator Cmp1. The ground terminal GND is connected to the other end of the capacitor C145 and the anode of the Zener diode D104, respectively.

[0052] 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 and the resistance values of the resistors R161, R162, R165, and R167. One end of the capacitor C142 and one end of the 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.

[0053] A power supply voltage of 3.3V is connected to the output terminal of the comparator Cmp1 via a 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 value of the current 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 is a circuit that receives the output result of the comparator Cmp1 and executes processing according to the received output result.

[0054] In Embodiment 1, the control circuit 400 is a PLD (Programmable Logic Device). In a certain aspect, the control circuit 400 may 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 a function of executing various processes by executing a program, but part or all of the functions of the processor may be an integrated circuit for specific use such as an FPGA (Field Programmable Gate Array) or an ASIC (Application Specific Integrated Circuit).

[0055] The term "processor" is not limited to a narrow sense processor that executes processing in a stored program manner such as a CPU or an MPU, and may include a hardwired circuit such as an ASIC or an FPGA. Therefore, the processor can also be read as a processing circuitry whose processing is defined in advance by computer-readable code and / or a hardwired circuit. Note that the processor may be composed of one chip or a plurality of chips.

[0056] Furthermore, the processor and related processing circuits may be composed of a plurality of computers interconnected by wire or wirelessly via a local area network or a wireless network, etc. The processor and related processing circuits may be composed of a cloud computer that remotely performs calculations based on input data and outputs the calculation results to other devices located at a distance.

[0057] FIG. 4 is a flowchart for discharge detection executed by the control circuit 400 in Embodiment 1. The control circuit 400 repeats the execution of the flowchart of FIG. 4 during the period when the high-voltage power supply unit 120 is being driven.

[0058] Based on the output result of the comparator Cmp1, the control circuit 400 determines whether a current equal to or greater than the first threshold value has been detected (step S110). If a current equal to or greater than the first threshold value has not been 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 value has been detected (YES in step S110), the control circuit 400 stops applying the PWM signal by the drive circuit 350 (step S120). As a result, the output from the high-voltage power supply unit 120 stops.

[0059] Thereafter, the control circuit 400 executes a discharge process (step S130). The discharge process in Embodiment 1 is a process that is executed when it is detected that a current larger than that in normal times including discharge has occurred. Specifically, in step S130, the control circuit 400 notifies the user that a current larger than that in normal times including discharge has occurred. The control circuit 400 notifies the user that discharge has occurred, for example, using a display device, a speaker, a transmitter, etc. provided in the fluorescent X-ray analyzer 1000. Also, the discharge process may be a process of storing the date and time when a current larger than that in normal times including discharge has occurred, rather than notifying the user that a current larger than that in normal times including discharge has occurred.

[0060] As described above, in Embodiment 1, the current detection circuit 600 included in the high-voltage power supply unit 120 can accurately detect discharge. When the power supply device 100 of Embodiment 1 detects discharge, it stops the operation of the high-voltage power supply unit 120.

[0061] [Embodiment 2] In Embodiment 1, the configuration in which the current detection circuit 600 has one comparator Cmp1 has been described. In Embodiment 1, the discharge process is executed when a current of 30 A or more, which is the first threshold value, is detected. However, in Embodiment 1, it is not possible to detect a discharge with a current less than the first threshold value (30 A).

[0062] In Embodiment 2, a fluorescence X-ray analyzer 1000 having a configuration that makes it easier to detect discharges at levels where the high-voltage power supply unit 120 does not malfunction will be described. In Embodiment 2, descriptions of configurations overlapping those of the fluorescence X-ray analyzer 1000 of Embodiment 1 will not be repeated.

[0063] FIG. 5 is a diagram for explaining the internal configuration of the current detection circuit 600A in Embodiment 2. As shown in FIG. 5, the current detection circuit 600A in Embodiment 2 has a comparator Cmp2 in addition to the comparator Cmp1. In Embodiment 2, the inverting input terminals of the comparator Cmp1 and the comparator Cmp2 are connected to the output terminal of the operational amplifier M1092 via a resistor R156. Note that the comparator Cmp2 may correspond to the "second comparator" in the present disclosure.

[0064] Comparator Cmp2, similar to comparator Cmp1, obtains the voltage values amplified by operational amplifiers M1091 and M1092, and transmits to control circuit 400 an output result indicating whether the current value detected by current detection circuit 600 is equal to or greater than a second threshold value. A power supply voltage of 2.5V is connected to the non-inverting input terminal of comparator Cmp2 via resistor R1. The voltage value at the non-inverting input terminal of comparator Cmp1 and the voltage value at the non-inverting input terminal of comparator Cmp2 are different voltage values. That is, the first threshold value for comparison by comparator Cmp1 and the second threshold value for comparison by comparator Cmp2 are different values. The second threshold value is lower than the first threshold value, for example, 25A. The second threshold value is a threshold value for detecting a discharge that generates a relatively low current value. That is, comparator Cmp2 is a comparator capable of detecting a discharge with a lower current value than the discharge detectable in Embodiment 1.

[0065] As shown in FIG. 5, 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 ground terminal GND. Capacitor C1 functions as a bypass capacitor.

[0066] A power supply voltage of 3.3V is connected to the output terminal of comparator Cmp2 via resistor R3. Comparator Cmp2 outputs a Low level from the output terminal when the value of the current detected by current detection circuit 600A is equal to or greater than the second threshold value. Also, comparator Cmp2 is configured to output a High level when the value of the current detected by current detection circuit 600A is less than the second threshold value. Control circuit 400 receives the output result of comparator Cmp2 and executes processing according to the received output result.

[0067] FIG. 6 is a flowchart for discharge detection executed by the control circuit 400 in the second embodiment. The control circuit 400 in the second embodiment repeats the execution of the flowchart in FIG. 6 during the period when the high-voltage power supply unit 120 is driving.

[0068] Based on the output result of the comparator Cmp2, the control circuit 400 determines whether a current equal to or greater than the second threshold value has been detected (step S210). If a current equal to or greater than the second threshold value is not detected (NO in step S210), the control circuit 400 ends the process.

[0069] If a current equal to or greater than the second threshold value is detected (YES in step S210), the control circuit 400 determines whether a current equal to or greater than the first threshold value has been detected based on the output result of the comparator Cmp1 (step S220). If the control circuit 400 does not detect a current equal to or greater than the first threshold value in step S220 (NO in step S220), it executes a discharge process (step S230). In the second embodiment as well, the discharge process is a process of notifying the user that a discharge has occurred, but it may also be a process of storing the date and time when a discharge occurred inside the X-ray tube 200 or the like without notifying the user that a discharge has occurred.

[0070] Returning to step S220, if the control circuit 400 detects a current equal to or greater than the first threshold value (YES in step S220), it stops applying the PWM signal to the drive circuit 350 (step S240). Thereafter, the control circuit 400 executes a discharge process (step S250).

[0071] Thus, in the second embodiment, it is possible to distinguish and detect an overcurrent at a level where the high-voltage power supply unit 120 fails 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 at a level where the high-voltage power supply unit 120 fails has occurred. Also in the second embodiment, similar to the first embodiment, a discharge can be detected using the current detection circuit 600 included in the high-voltage power supply unit 120. That is, also in the fluorescence X-ray analyzer 1000 in the second embodiment, the occurrence of a discharge can be accurately detected.

[0072] As described above, when a discharge occurs, the voltage on the output side of the high-voltage power supply unit 120 decreases. As the voltage on the output side decreases, the control circuit 400 increases the decreased output voltage by feedback control. At this time, the capacitor C100 is charged, and a large current temporarily flows through the primary side circuit 401 of the transformer. However, even when the set value of the output voltage of the high-voltage power supply unit 120 is changed by the user, a large current temporarily flows through the primary side circuit 401 of the transformer in order to charge the capacitor C100 again.

[0073] That is, when the set value of the output voltage of the high-voltage power supply unit 120 is changed by the user, the control circuit 400 may erroneously detect that a discharge has occurred. Therefore, in the second embodiment, by executing the following flowchart by the control circuit 400, when the set value of the output voltage of the high-voltage power supply unit 120 is changed, it is not determined that a discharge has occurred, thereby suppressing the erroneous detection of the discharge.

[0074] FIG. 7 is a flowchart at the time of output voltage change executed by the control circuit 400 in the second embodiment. The control circuit 400 of the second embodiment repeats the execution of the flowchart of FIG. 7 in addition to FIG. 6 during the period when the high-voltage power supply unit 120 is driven. The control circuit 400 determines whether or not 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 a signal from the outside indicating that the set value of the output voltage of the high-voltage power supply unit 120 has been changed.

[0075] If the set value of the output voltage has not been changed (NO in step S310), the control circuit 400 ends the process. If the set value of the output voltage has been changed (YES in step S310), the control circuit 400 determines whether or not a first period has elapsed since the set value of the output voltage was changed (step S320). If 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, the control circuit 400 determines that no discharge has occurred even if the detection result of the comparator Cmp1 indicates detection of a current equal to or greater than the first threshold value, or even if the detection result of the comparator Cmp2 indicates detection of a current equal to or greater than the second threshold value.

[0076] Thereafter, the control circuit 400 returns the process to step S320. That is, the control circuit 400 continues to ignore the output result of the comparator Cmp2 until the first period elapses since the set value of the output voltage was changed. In other words, the control circuit 400 does not determine that discharge has occurred even if a current value equal to or greater than the second threshold value is detected by the comparator Cmp2. The first period can be a value such as 10 ms, 100 ms, 1000 ms, etc. The value of the first period is changed according to the content of the change in the set value of the output voltage. If the first period has elapsed (YES in step S320), the control circuit 400 ends the process. Thereby, in the fluorescent X-ray analyzer 1000 of the second embodiment, it is possible to prevent false detection that discharge has occurred when the set value of the output voltage of the high-voltage power supply unit 120 is changed. Of course, the flowchart at the time of output voltage change shown in FIG. 7 can also be applied to the first embodiment having only one comparator.

[0077] <Modification Example> In the example of Embodiment 1, it was explained that after detecting that a current equal to or greater than the first threshold value has flowed, the control circuit 400 notifies the user that an abnormality such as discharge or short circuit has occurred. However, the control circuit 400 does not necessarily have to notify the user immediately after detecting that a current equal to or greater than the first threshold value has flowed. For example, based on the occurrence of a predetermined number of discharges within a predetermined period, the control circuit 400 may notify the user that an abnormality such as discharge or short circuit has occurred, and prompt the user to perform maintenance on the fluorescence X-ray analyzer 1000. Thereby, the fluorescence X-ray analyzer 1000 can notify the user at an appropriate timing when the X-ray tube 200, which is prone to frequent discharge, has deteriorated. The predetermined period is, for example, 1 hour, and the predetermined number of times is, for example, 50 times.

[0078] In addition, in the example of Embodiment 2, a configuration was described in which the control circuit 400 determines whether or not a current of the second threshold value has been detected in step S210, and then determines whether or not a current of the first threshold value has been detected in step S220. However, the order of detecting a current equal to or greater than the second threshold value and detecting a current equal to or greater than the first threshold value may be reversed, or the control circuit 400 may perform the detection of a current equal to or greater than the second threshold value and the detection of a current equal to or greater than the first threshold value in parallel.

[0079] In addition, in Embodiment 2, an example was described in which the control circuit 400 receives a change in the setting of the output voltage value from the outside, and 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 the superior control board may determine whether or not to execute the discharge process based on the detection result of the comparator Cmp2 input from the control circuit 400. In this case, when the superior control board receives a change in the setting of the output voltage from the user, it may ignore an instruction to perform a discharge process from the control circuit 400 for a certain period after the setting change.

[0080] [Aspect] Those skilled in the art will understand that the above-described multiple exemplary embodiments are specific examples of the following aspects.

[0081] (Item 1) A fluorescence X-ray analyzer (1000) according to one aspect includes an X-ray tube (200) including a filament (F1) and a target (Tg1) that irradiates a sample (S) with primary X-rays (10), a detector (300) that detects secondary X-rays (20) generated from the sample, a first power supply (120) that applies a tube voltage to the target, and a second power supply (110) that supplies a filament current to the filament. The first power supply includes a transformer (30), and a switching circuit (Mf1, Mf2) connected to a primary side of the transformer. The fluorescence X-ray analyzer further includes a current detection circuit (600) connected to the primary side of the transformer and detecting a current flowing through the primary side of the transformer, and a control circuit (400) that controls 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 or not the current detected by the current detection circuit is equal to or greater than the first threshold value. The control circuit detects that a discharge has occurred based on the fact that a current equal to or greater than the first threshold value has been detected by the current detection circuit.

[0082] According to the fluorescence X-ray analyzer 1000 described in Item 1, the occurrence of a discharge can be accurately detected.

[0083] (Item 2) In the fluorescence X-ray analyzer (1000) described in Item 1, the current detection circuit (600A) further includes a second comparator (Cmp2) configured to be able to detect whether or not the current detected by the current detection circuit is equal to or greater than a second threshold value that is lower than the first threshold value.

[0084] According to the fluorescent X-ray analyzer 1000 described in the second aspect, the control operation can be changed by using a plurality of threshold values.

[0085] (Third aspect) In the fluorescent X-ray analyzer (1000) described in the second aspect, the control circuit, 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 operation of the first power supply is stopped, 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 operation of the first power supply is not stopped.

[0086] According to the fluorescent X-ray analyzer 1000 described in the third aspect, when detecting a discharge exceeding the first threshold value set for the purpose of preventing circuit damage, the application of the PWM signal can be temporarily stopped. On the other hand, when a discharge exceeding the second threshold value smaller than the first threshold value is detected, only the discharge process is performed. In this way, by setting the second threshold value to a value larger than the current value during normal operation and smaller than the first threshold value, the discharge can be detected more accurately.

[0087] (Fourth aspect) In the fluorescent X-ray analyzer (1000) described in the third aspect, the control circuit determines that no discharge has occurred even if the current detected by the current detection circuit is equal to or greater than the second threshold value until the first period elapses after receiving a change in the set value of the output voltage of the first power supply.

[0088] According to the fluorescent X-ray analyzer 1000 described in the fourth aspect, it is possible to suppress the misdetection of the occurrence of discharge accompanying a change in the set value of the output voltage.

[0089] (Fifth aspect) In the fluorescent X-ray analyzer (1000) described in any one of the first to fourth aspects, When the control circuit determines that the discharge has occurred a predetermined number of times (for example, 100 times) within a predetermined period (for example, 1 hour), it prompts the user to perform maintenance on the fluorescent X-ray analyzer.

[0090] According to the fluorescent X-ray analyzer 1000 described in claim 5, it is possible to prompt the user to perform maintenance on the fluorescent X-ray analyzer according to the frequency of the generated discharge.

[0091] (Claim 6) In the fluorescent X-ray analyzer (1000) described in claim 1, After receiving a change in the set value of the output voltage of the first power supply, until a first period elapses, even if the current detected by the current detection circuit is equal to or greater than the first threshold value, the control circuit determines that the discharge has not occurred.

[0092] According to the fluorescent X-ray analyzer 1000 described in claim 6, it is possible to suppress the misdetection of the occurrence of discharge along with the change in the set value of the output voltage.

[0093] (Claim 7) A power supply device (100) according to one aspect is A power supply device (100) that supplies current to an X-ray tube (200) including a filament (F1) and a target (Tg1), A first power supply (120) that applies a tube voltage to the target, A second power supply (110) that supplies a filament current to the filament, and The first power supply is A transformer (30), And a switching circuit (Mf1, Mf2) connected to the primary side of the transformer, The power supply device (100) is Connected to the primary side of the transformer, and includes a current detection circuit (600) that detects the current flowing through the primary side of the transformer, And a control circuit (400) that controls 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 the first threshold value. Based on the fact that a current equal to or greater than the first threshold value is detected by the current detection circuit, the control circuit detects that discharge has occurred.

[0094] According to the power supply device 100 described in claim 7, the occurrence of discharge can be accurately detected.

[0095] The embodiments disclosed this time should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is shown not by the description of the above embodiments but by the claims, and it is intended that all modifications within the meaning and scope equivalent to the claims are included.

Explanation of Reference Numerals

[0096] 10 primary X-ray, 20 primary X-ray, 30 high-frequency transformer, 100 power supply device, 110 filament power supply unit, 111 filament current control unit, 120 high-voltage power supply unit, 125, 135 overcurrent protection circuit, 130 tube current control unit, 200 X-ray tube, 300 detector, 350 drive circuit, 400 control circuit, 401 transformer primary side circuit, 402 transformer secondary side circuit, 500 converter, 600, 600A current detection circuit, 1000 fluorescence X-ray analyzer, Am1, Am2 amplifier, Cmp1, Cmp2 comparator, Cp1 connection point, D1, D2, D104 Zener diode, T1, T1A, T2A, T2 terminal, F1 filament, GND ground terminal, L1, L1A, L3, L4, L5 power line, L10, Tr2, Tr11, Tr12 inductor, M1091, M1092 operational amplifier, Mf1, Mf2 switching element, P1A, P1 protection circuit, Sn1, Sn2 snubber circuit, Tg1 target.

Claims

1. An X-ray fluorescence analyzer, comprising: an X-ray tube that includes a filament and a target and irradiates a sample with primary X-rays; a detector that detects secondary X-rays generated from the sample; a first power supply that applies a tube voltage to the target; a second power supply that supplies a filament current to the filament, wherein the first power supply includes a transformer; and a switching circuit connected to a primary side of the transformer; the X-ray fluorescence analyzer further includes a current detection circuit connected to the primary side of the transformer and detecting a current flowing through 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 configured to be able to detect whether the current detected by the current detection circuit is equal to or greater than a first threshold; the control circuit detects that a discharge has occurred based on the fact that a current equal to or greater than the first threshold has been detected by the current detection circuit. An X-ray fluorescence analyzer.

2. The X-ray fluorescence analyzer according to claim 1, wherein the current detection circuit further includes a second comparator configured to be able to detect whether the current detected by the current detection circuit is equal to or greater than a second threshold that is lower than the first threshold.

3. 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 and equal to or greater than the first threshold; The X-ray fluorescence analyzer according to claim 2, wherein the control circuit does not stop 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 and less than the first threshold.

4. The X-ray fluorescence analyzer according to claim 3, wherein the control circuit determines that no discharge has occurred even if the current detected by the current detection circuit is equal to or greater than the second threshold until a first period has elapsed after receiving a change in a set value of an output voltage of the first power supply.

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

6. The fluorescence X-ray analyzer according to claim 1, wherein the control circuit determines that no discharge occurs even if the current detected by the current detection circuit is equal to or greater than the first threshold value until a first period elapses after receiving a change in the set value of the output voltage of the first power supply.

7. A power supply device that supplies current to an X-ray tube including a filament and a target, 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, wherein the first power supply includes a transformer, and a switching circuit connected to a primary side of the transformer, the power supply device further includes a current detection circuit connected to the primary side of the transformer and configured to detect a current flowing through the primary side of the transformer, and a control circuit configured to control 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, and the control circuit is a power supply device configured to detect that a 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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