Fluorescent x-ray analysis device and electric power unit

Abstract

To suppress a tube current from leaking at a Zener diode of a device which emits X rays.SOLUTION: A fluorescent x-ray analysis device (1000) comprises: an X-ray tube (200) which emits primary X rays (10); a first power supply (110) which supplies a filament current; a second power supply (120) which applies a tube voltage; a first diode (D33) which is connected to an electric power line; a Zener diode (D34) which is connected to a ground terminal; and an operational amplifier (M7) which has an output terminal, an inverting input terminal, and a noninverting input terminal. The noninverting input terminal is connected to the electric power line, and the output terminal is connected to a second terminal and the inverting input terminal.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to an X-ray fluorescence analyzer and a power supply device. [Background technology]

[0002] Conventionally, there is known an X-ray fluorescence analyzer that analyzes a sample by irradiating the sample with X-rays. Patent Document 1 (International Publication No. 2018 / 002977) describes that a filament and a target arranged at a distance from each other are arranged in an X-ray tube. The analyzer of Patent Document 1 generates a tube current by applying a tube voltage between the filament and the target, and generates X-rays by the collision of thermal electrons with the target.

[0003] X-rays generated by the impact of thermal electrons on a target are called "primary X-rays." A solid, granular, or liquid sample is irradiated with primary X-rays, which cause the sample to emit fluorescent X-rays. In analytical instruments that use fluorescent X-rays, the emitted fluorescent X-rays are detected by a spectroscope to perform qualitative or quantitative analysis of the elements contained in the sample.

[0004] The analyzer of Patent Document 1 has a tube voltage control circuit that applies a high voltage to the target and a filament current control circuit that supplies a constant current to the filament. The tube voltage control circuit performs feedback control so that the potential of the target does not deviate from a target tube voltage value. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication No. 2018 / 002977 Summary of the Invention [Problem to be solved by the invention]

[0006] In such an analytical device, a Zener diode may be provided as a protection circuit in case of unintentional discharge caused by application of a high voltage. When a discharge exceeding the Zener voltage occurs, the Zener diode passes the discharge current to the ground terminal to protect the circuitry within the analytical device.

[0007] However, due to its characteristics, a Zener diode generates a leakage current called a "reverse current" when a reverse voltage smaller than the Zener voltage is applied. For this reason, when a tube voltage is applied to generate primary X-rays and a tube current flows due to the application of the tube voltage, a leakage current occurs in the Zener diode. Since the tube current control circuit performs feedback control using the current value after being affected by the leakage current as an input, in the X-ray analysis device, there are cases where a discrepancy occurs between the tube current value as an input value for feedback control and the tube current value actually flowing through the tube.

[0008] The present disclosure has been made to solve the above-mentioned problems, and has as its objective to suppress leakage of tube current in a Zener diode for discharge protection in a fluorescent X-ray analyzer that generates X-rays by applying a tube voltage to a filament and a target. [Means for solving the problem]

[0009] An X-ray fluorescence analyzer according to an aspect of the present disclosure includes an X-ray tube including a filament and a target and irradiating a sample with primary X-rays, a detector for detecting secondary X-rays generated from the sample, a first power supply for supplying a filament current to the filament via a power line, a second power supply for applying a tube voltage to the target, a first diode having a first terminal and a second terminal with the first terminal connected to the power line, a Zener diode having a third terminal and a fourth terminal with the third terminal connected to the second terminal and the fourth terminal connected to a ground terminal, and an operational amplifier having an output terminal, an inverting input terminal, and a non-inverting input terminal. The non-inverting input terminal is connected to the power line, and the output terminal is connected to the second terminal and the inverting input terminal.

[0010] A power supply device according to another aspect of the present disclosure is a power supply device that supplies a current to an X-ray tube including a filament and a target. The power supply device includes a first power supply that supplies a filament current to the filament via a power line, a second power supply that applies a tube voltage to the target, a first diode having a first terminal and a second terminal, the first terminal being connected to the power line, a Zener diode having a third terminal and a fourth terminal, the third terminal being connected to the second terminal and the fourth terminal being connected to a ground terminal, and an operational amplifier having an output terminal, an inverting input terminal, and a non-inverting input terminal. The non-inverting input terminal is connected to the power line, and the output terminal is connected to the second terminal and the inverting input terminal. Effect of the Invention

[0011] According to the present disclosure, in a fluorescent X-ray analyzer that generates X-rays by applying a tube voltage to a filament and a target, it is possible to suppress leakage of tube current in a Zener diode for discharge protection. [Brief description of the drawings]

[0012] [Figure 1] FIG. 2 is a diagram illustrating a power supply device and an X-ray tube of the fluorescent X-ray analyzer. [Diagram 2] FIG. 2 is an equivalent circuit diagram of a protection circuit. [Diagram 3] FIG. 2 is a circuit diagram for explaining a power supply for an operational amplifier. [Figure 4] 1 is a circuit diagram from terminal T1 to terminal T2 in a power supply device in a comparative example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] [Embodiment Mode] The present embodiment will now be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are designated by the same reference characters and, in principle, descriptions thereof will not be repeated.

[0014] <Power supply and X-ray tube configuration> 1 is a diagram that shows a schematic diagram of a power supply device 100 and an X-ray tube 200 of an X-ray fluorescence analyzer 1000. The X-ray fluorescence analyzer 1000 is, for example, an energy dispersive X-ray fluorescence spectrometer (EDX: Energy Dispersive X-ray Fluorescence Spectrometer). In this embodiment, an example in which the power supply device 100 that generates primary X-rays is applied to the X-ray fluorescence analyzer 1000 will be described.

[0015] As shown in FIG. 1, 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. A sample S is irradiated with the primary X-rays 10. The sample S irradiated with the primary X-rays 10 emits fluorescent X-rays 20. The fluorescent X-rays 20 emitted from the sample S are called "secondary X-rays" in contrast to the primary X-rays. The detector 300 detects the fluorescent X-rays 20. This allows the fluorescent X-ray analysis apparatus 1000 to perform quantitative or qualitative analysis of the sample S.

[0016] The X-ray tube 200 has a target Tg1 and a filament F1. The target Tg1 is an anode, and the filament F1 is a cathode. The target Tg1 and the filament F1 are arranged at a distance from each other within the X-ray tube 200. The power supply device 100 includes a filament power supply unit 110, a high-voltage power supply unit 120, and a tube current control unit 130.

[0017] The filament power supply unit 110 applies a voltage to both ends of the filament F1 to heat the filament F1. Hereinafter, the current supplied by the voltage application of the filament power supply unit 110 is referred to as the "filament current." The high voltage power supply unit 120 applies a high voltage to the target Tg1 and the filament F1. Hereinafter, the high voltage applied by the high voltage power supply unit 120 is referred to as the "tube voltage." The tube current control unit 130 performs feedback control to adjust the output of the filament power supply unit 110 based on the value of the current flowing through the power line L4.

[0018] In the X-ray tube 200, thermoelectrons are generated by heating the filament F1 by the filament power supply unit 110. A tube voltage is applied between the filament F1 and the target Tg1 by the high-voltage power supply unit 120, so that the thermoelectrons collide with the target Tg1. As a result, 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. The connection point Cp1 is a 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. In one example, the resistance values ​​of the resistors R316 and R322 are 100Ω, and the rated power is 0.5W. 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, instead of the connection point Cp1, the 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.

[0020] A protection circuit P1 is connected to the power line L1 between terminals T1 and T2. Similarly, a protection circuit P1A is connected to the power line L1A between terminals T1A and T2A. The protection circuits P1 and P1A have Zener diodes, which will be described later.

[0021] As a result, even if an unintended discharge occurs in the X-ray tube 200, the protection circuits P1, P1A can protect the filament power supply unit 110 and the tube current control unit 130 from overvoltage generated by the discharge. When the control unit of the high-voltage power supply unit 120 and the tube current control unit 130 are mounted on the same board, the protection circuits P1, P1A can also protect the high-voltage power supply unit 120 from overvoltage generated by the discharge.

[0022] The high-voltage power supply unit 120 has electric circuits such as a transformer and a rectifier, and generates a high voltage to be applied to the X-ray tube 200. As shown in Fig. 1, the high-voltage power supply unit 120 is connected to the target Tg1 via a power line L3. The high-voltage power supply unit 120 is also connected to a ground terminal GND via a power line L5.

[0023] The filament power supply unit 110 supplies a filament current to the filament F1 of the X-ray tube 200 to adjust the tube current. The tube current control unit 130 detects the tube current flowing through the power line L4 using a resistor, converts it into a voltage, and amplifies it using an amplifier Am1 to detect the tube current value flowing through the power line L4. The tube current control unit 130 transmits the detected tube current value to the filament current control unit 111. The tube current flowing through the power line L4 returns to the high-voltage power supply unit 120 from the power line L5 via a resistor and a ground terminal GND. The tube current value transmitted by the tube current control unit 130 to the filament current control unit 111 may be determined to be valid or not based on a predetermined upper limit value and a predetermined lower limit value of the filament current. An error amplifier may be disposed on the output side of the amplifier Am1 in the tube current control unit 130.

[0024] The filament current control unit 111 controls the output of the filament current according to the tube current value detected by the tube current control unit 130. In this manner, in the fluorescent X-ray analysis apparatus 1000 of this embodiment, feedback control of the filament current is performed based on the tube current value flowing through the power line L4. The filament power supply unit 110 may correspond to the "first power supply unit" in this disclosure. The high-voltage power supply unit 120 may correspond to the "second power supply unit" in this disclosure.

[0025] <Electric circuit configuration> Fig. 2 is an equivalent circuit diagram of the protection circuit P1. With reference to Fig. 2, the power supply device 100 includes, as the protection circuit P1 between the terminals T1 and T2, capacitors C32-C39, Schottky diodes D31, D32, D33, and D35, a Zener diode D34, an operational amplifier M7, and resistors R31-R33. The protection circuit P1A has a similar configuration to the protection circuit P1 shown in Fig. 2. Therefore, description of the protection circuit P1A will not be repeated below.

[0026] As shown in FIG. 2, the power line L1 connects the terminal T1 and the terminal T2. One end of each of the capacitors C32-C37 is connected to the power line L1. The other end of each of the capacitors C32-C37 is connected to the ground terminal GND. In this way, in the power supply device 100, when a discharge current flows through the power line L1 due to an unintended high-voltage discharge, the capacitors C32-C37 can suppress a voltage rise. In the example of FIG. 2, the number of the capacitors C32-C37 is six. Note that the total capacitance value of the capacitors C32-C37 provided for the purpose of suppressing a voltage rise is preferably equal to or less than a capacitance that does not affect the control of the tube current control unit 130.

[0027] In one example, the capacitance of capacitors C32 and C33 is 100 pF and the rated voltage is 100 V. The capacitance of capacitors C34 and C35 is 2200 pF and the rated voltage is 100 V. The capacitance of capacitors C36 and C37 is 0.01 μF and the rated voltage is 250 V. Thus, in this embodiment, six capacitors C32 to C37 are provided for the purpose of suppressing a voltage rise accompanying the discharge of a high voltage. Each of capacitors C32 to C37 may correspond to a "first capacitor" in the present disclosure.

[0028] The power supply device 100 has a Schottky diode D33. The Schottky diode D33 has a terminal E1 and a terminal E2. In the example of Fig. 2, the terminal E1 is an anode and the terminal E2 is a cathode. The terminal E1 is connected to the power line L1. The terminal E2 is connected to the Zener diode D34.

[0029] The Schottky diode D33 may correspond to a "first diode" in this disclosure. The terminal E1 of the Schottky diode D33 may correspond to a "first terminal" in this disclosure. The terminal E2 of the Schottky diode D33 may correspond to a "second terminal" in this disclosure.

[0030] In this embodiment, the Zener diode D34 is a bidirectional Zener diode. That is, the Zener diode D34 has two Zener diodes arranged opposite to each other. The Zener diode D34 has a terminal E3 and a terminal E4. The terminal E3 of the Zener diode D34 is connected to the terminal E2 of the Schottky diode D33. The terminal E4 is connected to the ground terminal GND. The terminal E3 of the Zener diode D34 may correspond to the "third terminal" in this disclosure. The terminal E4 of the Zener diode D34 may correspond to the "fourth terminal" in this disclosure. In this embodiment, the Zener diode D34 is, more specifically, a transient-voltage suppression (TVS) diode.

[0031] The power supply device 100 has a Schottky diode D31 in addition to the Schottky diode D33. The Schottky diode D31 has a terminal E5 and a terminal E6. In the example of FIG. 2, the terminal E5 is a cathode, and the terminal E6 is an anode. The Schottky diode D31 may correspond to a "second diode" in the present disclosure. The terminal E5 of the Schottky diode D31 may correspond to a "fifth terminal" in the present disclosure. The terminal E6 of the Schottky diode D31 may correspond to a "sixth terminal" in the present disclosure. The Schottky diodes D31 and D33 may be other types of diodes, such as fast recovery diodes (FRDs).

[0032] As shown in Fig. 2, in the power supply device 100 in this embodiment, the Schottky diodes D31 and D33 are connected in parallel so that the anode and cathode directions are opposite to each other. When an unintended discharge occurs in the X-ray tube 200, it is impossible to determine which polarity of the discharge current flows through the power line L1. Therefore, as shown in Fig. 2, by connecting the Schottky diodes D31 and D33 in parallel with the power line L1, whose anode and cathode directions are opposite to each other, the discharge current can be caused to flow from the power line L1 to the Zener diode D34 via either of the Schottky diodes D31 and D33, regardless of the polarity of the discharge current.

[0033] In this embodiment, the power supply device 100 has an operational amplifier M7 for configuring a voltage follower circuit. The operational amplifier M7 has an inverting input terminal, a non-inverting input terminal, and an output terminal, and is connected between the power line L1 and a connection node N10. The connection node N10 is a connection node between the Schottky diode D33 and the Zener diode D34.

[0034] The output terminal of the operational amplifier M7 is connected to the connection node N10 via resistors R31 and R32 connected in series. The non-inverting input terminal of the operational amplifier M7 is connected to the power line L1 via a resistor R33. The output terminal of the operational amplifier M7 is also connected to the inverting input terminal of the operational amplifier M7. The resistors R31 and R32 are provided to protect the operational amplifier M7. In one example, the resistance value of the resistors R31 and R32 is 100Ω, and the rated power is 0.5W.

[0035] A clamp circuit is formed between resistor R32 and the output terminal of operational amplifier M7 by Schottky diodes D32 and D35. Fig. 3 is a circuit diagram for explaining the power supply of operational amplifier M7. A +15V DC power supply is connected to the positive power supply terminal of operational amplifier M7. A -5V DC power supply is connected to the negative power supply terminal of operational amplifier M7. Note that the voltage values ​​of the positive power supply terminal and the negative power supply terminal of operational amplifier M7 are merely examples, and other voltage values ​​may be used.

[0036] Capacitors C48, C49, C50, and C51 and resistors R37 and R38 are connected to the power supply line of the operational amplifier M7. The capacitors C48, C49, C50, and C51 are so-called bypass capacitors. In one example, the capacitance of the capacitors C49 and C50 is 0.1 μF and the rated voltage is 100 V. The capacitance of the capacitors C48 and C51 is 4.7 μF and the rated voltage is 50 V. The provision of the capacitors C48 to C51 and the resistors R37 and R38 makes it possible to reduce noise generated in the power supply line of the operational amplifier M7. In addition, the capacitors C48 to C51 and the Schottky diodes D32 and D35 suppress the voltage rise at the output terminal of the operational amplifier M7 and protect the operational amplifier M7.

[0037] 2, as described above, the output terminal of the operational amplifier M7 is connected to the inverting input terminal of the operational amplifier M7. Since the operational amplifier M7 functions as a voltage follower circuit, the output voltage of the operational amplifier M7 has the same potential as the input voltage from the non-inverting input terminal.

[0038] As a result, the potential difference between the terminal E2 of the Schottky diode D33 connected to the output terminal of the operational amplifier M7 and the power line L1 connected to the input terminal of the operational amplifier M7 becomes close to zero. Similarly, the potential difference between the terminal E6 of the Schottky diode D31 connected to the output terminal of the operational amplifier M7 and the power line L1 connected to the input terminal of the operational amplifier M7 becomes close to zero. In the Schottky diodes D31 and D33, a current flows when there is a difference between the anode voltage and the cathode voltage. In this embodiment, the operational amplifier M7 makes the difference between the anode voltage and the cathode voltage of the Schottky diodes D31 and D33 close to zero.

[0039] As a result, during a period when no discharge occurs and tube current flows due to application of a tube voltage for generating primary X-rays, the current value flowing through the Schottky diodes D31 and D33 is close to zero. Fig. 4 is a circuit diagram from terminal T1 to terminal T2 in the power supply device 100Z of the comparative example. In the power supply device 100Z of the comparative example, a voltage follower circuit using an operational amplifier M7 is not provided, and the Zener diode D34 is directly connected to the power line L1.

[0040] In the comparative example, during the period when a tube voltage is applied to generate primary X-rays 10 and a tube current flows, a voltage equal to or lower than the operating voltage of Zener diode D34 continues to be applied to Zener diode D34, and a part of the tube current flowing in power line L1 flows into ground terminal GND as a leakage current. As a result, in the comparative example, the occurrence of leakage current causes a difference between the tube current value actually flowing in the tube and the current value used as an input for feedback control (the current value flowing in power line L4).

[0041] On the other hand, in the power supply device 100 of the present embodiment shown in Fig. 2, during a period in which a tube voltage is applied to generate the primary X-rays 10 and a tube current flows, the voltage follower circuit formed by the operational amplifier M7 makes the potential difference between both terminals of the Schottky diodes D31 and D33 approach zero. That is, the value of the current flowing from the power line L1 to the Zener diode D34 via the Schottky diodes D31 and D33 approaches zero. As a result, in the present embodiment, it is possible to suppress leakage of the tube current in the Zener diode D34.

[0042] The capacitor C38 is connected in parallel to the Schottky diode D33 between the power line L1 and the Zener diode D34. More specifically, one end of the capacitor C38 is connected to the power line L1, and the other end of the capacitor C38 is connected to the terminal E3 of the Zener diode D34 via a connection node N10.

[0043] As a result, in the power supply device 100, when a discharge occurs and a discharge current flows into the Schottky diodes D31 and D33, a temporary path is formed by the capacitor C38 as a path through which the discharge current flows from the power line L1 to the Zener diode D34. The discharge current basically flows through the Schottky diode D31 or the Schottky diode D33. The capacitor C38 is provided as a path through which the discharge current flows from the power line L1 to the Zener diode D34 until the Schottky diode D31 or the Schottky diode D33 becomes conductive. The capacitor C38 may correspond to the "second capacitor" in this disclosure.

[0044] <Response speed> In this embodiment, the response speed of the voltage follower circuit formed by the operational amplifier M7 is adjusted within a predetermined range. If the response speed of the voltage follower circuit is too fast, even if a discharge occurs, the potential difference between both terminals of the Schottky diodes D31 and D33 approaches zero due to the voltage follower circuit, and the discharge current cannot flow to the Zener diode D34.

[0045] On the other hand, if the response speed of the voltage follower circuit is too slow, a potential difference may occur between both terminals of the Schottky diodes D31 and 33 during a period when a tube voltage is applied to generate primary X-rays and a tube current flows without generating a discharge. Specifically, when the voltage value of the power line L1 fluctuates due to a fluctuation in the current value flowing through the power line L1, if the response speed of the voltage follower circuit is too slow, a potential difference corresponding to the fluctuation occurs between both terminals of the Schottky diodes D31 and 33. As a result, the tube current flows from the Schottky diode D31 to the Zener diode D34, causing a tube current leak. At this time, if the response speed of the voltage follower circuit is slower than the response speed of the feedback control of the tube current control, a discrepancy occurs between the tube current value as an input value of the feedback control and the tube current value actually flowing through the tube.

[0046] It is desirable that the response speed of the voltage follower circuit is within a predetermined range. In this embodiment, the response speed of the voltage follower circuit is adjusted using a resistor R33 and a capacitor C39. In one example, the resistance value of the resistor R33 is 10 kΩ, and the rated power is 0.25 W. The capacitance of the capacitor C39 is 2200 pF, and the rated voltage is 100 V.

[0047] One end of a resistor R33 is connected to the power line L1. The other end of the resistor R33 is connected to the non-inverting input terminal of the operational amplifier M7 and one end of a capacitor C39. The other end of the capacitor C39 is connected to a ground terminal. The capacitor C39 and the resistor R33 function as a delay circuit.

[0048] This makes it possible to slow down the response speed of the voltage follower circuit when the voltage value of the power line L1 fluctuates due to fluctuations in the value of the current flowing through the power line L1. That is, in this embodiment, by providing the resistor R33 and the capacitor C39, it is possible to adjust the response speed of the voltage follower circuit formed by the operational amplifier M7. Furthermore, the capacitor C39 and the resistor R33 also serve to protect the operational amplifier M7. Thus, in this embodiment, a filter circuit that functions as a delay circuit is formed on the input side of the operational amplifier M7.

[0049] In this embodiment, a filter circuit is also formed by the parasitic capacitance of the Zener diode D34 and the resistors R31 and R32. In this embodiment, the Zener diode D34 and the resistors R31 and R32 are provided, so that the operational amplifier M7 can be protected. In this manner, in this embodiment, a filter circuit is formed not only on the input side of the operational amplifier M7 but also on the output side.

[0050] As described above, in this embodiment, the leakage of the tube current in the Zener diode D34 is suppressed, thereby suppressing the occurrence of a discrepancy between the tube current value as an input value for feedback control and the tube current value actually flowing through the tube. When the tube current value flowing through the power line L4 is small, the influence of the leakage current on the discrepancy between the tube current value as an input value for feedback control and the tube current value actually flowing through the tube becomes large. In this embodiment, even when the influence of the leakage current becomes large because the tube current value is small, the occurrence of the leakage of the tube current in the Zener diode D34 itself can be suppressed, thereby suppressing the discrepancy between the tube current value as an input value for feedback control and the tube current value actually flowing through the tube.

[0051] Furthermore, in this embodiment, the value of the current flowing into the Zener diode D34 via the Schottky diodes D31 and D33 can be made close to zero. Therefore, in this embodiment, it is possible to suppress leakage of the tube current regardless of the characteristics of the Zener diode D34.

[0052] In addition, in this embodiment, since the circuit is composed of general electronic components such as Zener diodes, Schottky diodes, capacitors, and operational amplifiers, it is possible to suppress an increase in costs. It is possible to correct the set value of the tube current using a correction coefficient to correct the error caused by the leakage of the tube current in the Zener diode, but in this case, development costs for software to calculate the correction coefficient are incurred. In this embodiment, it is possible to suppress the occurrence of a discrepancy between the tube current value as the input value for feedback control and the tube current value actually flowing through the tube without incurring development costs for software to correct the feedback control.

[0053] Furthermore, in the power supply device 100 of the present embodiment, leakage of the tube current can be suppressed regardless of the temperature fluctuation and discharge protection performance of the Zener diode D34.

[0054] In the present embodiment, an example has been described in which the power supply device 100 that generates X-rays is applied to a fluorescent X-ray analyzer 1000. However, the power supply device 100 that generates X-rays can be applied to, for example, an X-ray device, a CT device, a radiography device, etc., other than a fluorescent X-ray analyzer. In other words, the power supply device 100 can be applied to a wide variety of devices that apply a tube voltage to a filament F1 and a target Tg1 to generate X-rays.

[0055] [Aspects] It will be appreciated by those skilled in the art that the exemplary embodiments described above are examples of the following aspects.

[0056] (Item 1) An X-ray fluorescence analyzer according to one embodiment includes an X-ray tube including a filament and a target and irradiating a sample with primary X-rays, a detector for detecting secondary X-rays generated from the sample, a first power supply for supplying a filament current to the filament via a power line, a second power supply for applying a tube voltage to the target, a first diode having a first terminal and a second terminal with the first terminal connected to the power line, a Zener diode having a third terminal and a fourth terminal with the third terminal connected to the second terminal and the fourth terminal connected to a ground terminal, and an operational amplifier having an output terminal, an inverting input terminal, and a non-inverting input terminal. The non-inverting input terminal is connected to the power line, and the output terminal is connected to the second terminal and the inverting input terminal.

[0057] According to the fluorescent X-ray analyzer described in paragraph 1, in an X-ray fluorescent analyzer that generates X-rays by applying a tube voltage to a filament and a target, leakage of tube current in a Zener diode for discharge protection can be suppressed.

[0058] (Item 2) The fluorescent X-ray analyzer described in item 1 further includes a second diode having a fifth terminal and a sixth terminal, the fifth terminal being connected to a power line, the sixth terminal being connected to the third terminal and the output terminal, the first terminal being an anode, the second terminal being a cathode, the fifth terminal being a cathode, the sixth terminal being an anode, and the Zener diode being a bidirectional Zener diode.

[0059] According to the fluorescent X-ray analysis apparatus 1000 described in the second aspect, a discharge current can be caused to flow from the power line to the Zener diode via any one of the Schottky diodes, regardless of the direction of the polarity of the discharge current.

[0060] (Item 3) The fluorescent X-ray analyzer according to item 1 or 2, further comprising a first capacitor having one end connected to the power line and the other end connected to a ground terminal.

[0061] According to the fluorescent X-ray analyzer described in the third aspect, when a discharge current flows through the power line due to an unintended high-voltage discharge, the first capacitor can suppress a rise in voltage.

[0062] (Item 4) The fluorescent X-ray analyzer according to any one of items 1 to 3, further comprising a second capacitor connected in parallel to the first diode.

[0063] According to the X-ray fluorescence analysis apparatus described in paragraph 4, when a discharge occurs and a discharge current flows into the Schottky diode, a temporary path can be formed by the capacitor as a path through which the discharge current flows from the power line to the Zener diode.

[0064] (Item 5) The fluorescent X-ray analyzer according to any one of items 1 to 4, further comprising a filter circuit provided in at least one of the non-inverting input terminal and the output terminal.

[0065] According to the X-ray fluorescence analyzer described in paragraph 5, by providing at least one of a resistor and a capacitor, or a Zener diode and a resistor, it is possible to adjust the response speed of the voltage follower circuit formed by the operational amplifier. This makes it possible for the voltage follower circuit to be configured not to follow voltage fluctuations in the power line.

[0066] (Item 6) The fluorescent X-ray analyzer according to any one of items 1 to 5, further comprising a clamp circuit connected to the output terminal.

[0067] According to the fluorescent X-ray analyzer described in item 6, the operational amplifier can be protected. (Item 7) A power supply device according to one embodiment is a power supply device that supplies a current to an X-ray tube including a filament and a target. The power supply device includes a first power supply that supplies a filament current to the filament via a power line, a second power supply that applies a tube voltage to the target, a first diode having a first terminal and a second terminal, the first terminal being connected to the power line, a Zener diode having a third terminal and a fourth terminal, the third terminal being connected to the second terminal and the fourth terminal being connected to a ground terminal, and an operational amplifier having an output terminal, an inverting input terminal, and a non-inverting input terminal. The non-inverting input terminal is connected to the power line, and the output terminal is connected to the second terminal and the inverting input terminal.

[0068] According to the power supply device 100 described in paragraph 7, in a fluorescent X-ray analyzer that generates X-rays by applying a tube voltage to a filament and a target, leakage of a tube current in a Zener diode for discharge protection can be suppressed.

[0069] The embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The scope of the present invention is defined by the claims, not by the description of the embodiments described above, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0070] 110 filament power supply unit, 111 filament current control unit, 120 high voltage power supply unit 130 tube current control section, 200 X-ray tube, 300 detector, 1000 X-ray analyzer, Am1 amplifier, C32-C39, C48-C51 capacitors, D31-D33, D35 Schottky diodes, D34A, D34 Zener diodes, E1-E4 terminals, F1 filament, GND ground terminal, L1A, L1-L4 power lines, M7 operational amplifier, N1Z, N1-N11, N14, N17 connection nodes, R31, R32, R33, R37, R38 resistors, S sample, T1A, T1, T2, T2A terminals, Tg1 target.

Claims

1. an X-ray tube including a filament and a target for irradiating a sample with primary X-rays; a detector for detecting secondary X-rays generated from the sample; a first power source that supplies a filament current to the filament via a power line; A second power source that applies a tube voltage to the target; a first diode having a first terminal and a second terminal, the first terminal being connected to the power line; a Zener diode having a third terminal and a fourth terminal, the third terminal being connected to the second terminal and the fourth terminal being connected to a ground terminal; an operational amplifier having an output terminal, an inverting input terminal, and a non-inverting input terminal; the non-inverting input terminal is connected to the power line; The output terminal is connected to the second terminal and the inverting input terminal.

2. a second diode having a fifth terminal and a sixth terminal, the fifth terminal being connected to the power line; the sixth terminal is connected to the third terminal and the output terminal; the first terminal is an anode; the second terminal is a cathode; the fifth terminal is a cathode; the sixth terminal being an anode; 2. The X-ray fluorescence analysis apparatus according to claim 1, wherein the Zener diode is a bidirectional Zener diode.

3. 3. The X-ray fluorescence analysis apparatus according to claim 1, further comprising a first capacitor having one end connected to the power line and the other end connected to a ground terminal.

4. 3. The X-ray fluorescence analysis apparatus according to claim 1, further comprising a second capacitor connected in parallel to the first diode.

5. 3. The X-ray fluorescence analysis apparatus according to claim 1, further comprising a filter circuit provided in at least one of the non-inverting input terminal and the output terminal.

6. 3. The X-ray fluorescence analysis apparatus according to claim 1, further comprising a clamp circuit connected to the output terminal.

7. 1. A power supply for supplying current to an X-ray tube including a filament and a target, comprising: a first power source that supplies a filament current to the filament via a power line; A second power source that applies a tube voltage to the target; a first diode having a first terminal and a second terminal, the first terminal being connected to the power line; a Zener diode having a third terminal and a fourth terminal, the third terminal being connected to the second terminal and the fourth terminal being connected to a ground terminal; an operational amplifier having an output terminal, an inverting input terminal, and a non-inverting input terminal; the non-inverting input terminal is connected to the power line; The output terminal is connected to the second terminal and the inverting input terminal.

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