X-ray generating device, and diagnostic device and diagnostic method for the X-ray generating device

Abstract

The X-ray tube (120) includes: a cathode (140) and an anode (150), the cathode (140) and the anode (150) being sealed inside a vacuum housing (121); and an ion collecting conductor (130) mounted on the vacuum housing in a manner of contacting the inner space of the vacuum housing. A first current sensor (210) measures a first current value (Ii) flowing between the ion collecting conductor (130) and a node (Ng), the node (Ng) supplying a potential for attracting positive ions in the vacuum housing (121). A second current sensor (180) measures a second current value (Ie) flowing between the anode (150) and the cathode (140). A control circuit (190) generates diagnostic information related to the vacuum degree of the X-ray tube (120) based on a current ratio (Ii / Ie) between the second current value (Ie) measured by the second current sensor (180) and the first current value (Ii) measured by the first current sensor (210).

Description

Technical Field

[0001] The present invention relates to an X-ray generating device and a diagnostic device and a diagnostic method for the X-ray generating device. Background Art

[0002] X-ray generators are widely used in analytical devices, medical equipment, etc. In general, an X-ray generator is configured such that electrons released from a cathode are accelerated by applying a high voltage between an anode and a cathode in a vacuum-sealed X-ray tube, and the electrons collide with a target formed on the surface of the anode, thereby generating X-rays.

[0003] When the vacuum level in the X-ray tube deteriorates due to aging, that is, the pressure increases, discharge will occur and the tube needs to be replaced. Therefore, as a method of predicting the life of the tube by detecting the deterioration of the vacuum level in a non-destructive manner, the technology described in Japanese Patent Publication No. 2006-100174 (Patent Document 1) and Japanese Patent Publication No. 2016-146288 (Patent Document 2) is proposed.

[0004] Patent Document 1 discloses a structure in which a vacuum measuring unit having an ion gauge sphere for an ionization vacuum gauge built therein is installed in a vacuum envelope of an X-ray tube to measure the vacuum degree inside the vacuum envelope.

[0005] Patent document 2 discloses the following technology: the electric field between the anode and the cathode is set in the opposite direction to that when X-rays are generated, and the vacuum degree of the X-ray tube is measured based on the correlation between the measured current and the vacuum degree flowing between the anode and the cathode when ionized gas molecules in the X-ray tube are attracted to the anode.

[0006] Prior art literature

[0007] Patent Literature

[0008] Patent Document 1: Japanese Patent Application Publication No. 2006-100174

[0009] Patent Document 2: Japanese Patent Application Publication No. 2016-146288 Summary of the invention

[0010] Problem that the invention aims to solve

[0011] However, in the structure of Patent Document 1, since the vacuum measuring unit is installed in the vacuum housing, the vacuum degree at the installation location may be deteriorated, and the cost may be increased due to the addition of a new structure. On the other hand, in Patent Document 2, there is no need to change the structure of the X-ray tube including the vacuum housing, but when measuring the vacuum degree, there is a new need for a mechanism for applying a voltage between the cluster and the filament (electron source), and a mechanism for generating an electric field between the anode and the cathode in the opposite direction to that when generating X-rays.

[0012] In Patent Document 2, the current corresponding to the amount of ions generated by collisions between electrons released from the cathode and gas molecules is measured using the same principle as that of an ionization vacuum gauge, thereby quantitatively measuring the gas molecules. Therefore, the measured current varies not only depending on the molecular weight of the gas present in the X-ray tube, but also depending on the amount of released electrons. On the other hand, in Patent Document 2, the life of the X-ray tube is predicted based on the correlation between the measured current and the vacuum degree obtained in advance. Therefore, if the amount of electrons released from the cathode when measuring the vacuum degree is different from the amount of electrons released when the correlation is obtained due to changes in the device over the years, changes in the power supply voltage, and individual differences in the X-ray tubes, errors may occur in the measurement of the vacuum degree, that is, in the diagnosis of the life of the X-ray tube.

[0013] The present invention has been made to solve such a problem, and an object of the present invention is to perform degradation diagnosis of an X-ray tube with high accuracy using a simple structure.

[0014] Solutions for solving problems

[0015] The first embodiment of the present invention relates to an X-ray generating device. The X-ray generating device includes an X-ray tube, a first DC power supply and a second DC power supply, a first current sensor and a second current sensor, and a control circuit. The X-ray tube includes: a cathode and an anode, the cathode and the anode are sealed inside a vacuum shell; and an ion collecting conductor, which is installed in the vacuum shell in a manner of contacting the internal space of the vacuum shell. The cathode has an electron source that releases electrons. The anode and the cathode are arranged opposite to each other, and the anode is configured to emit X-rays by incident electrons released from the electron source. The first DC power supply applies a first DC voltage that becomes the release energy of the electrons to the electron source. The second DC power supply applies a second DC voltage between the cathode and the anode, and the second DC voltage is used to generate an electric field with the anode as the high potential side. The first current sensor measures a first current value flowing between the ion collecting conductor and a node, and the node supplies a potential for attracting cations in the vacuum shell. The second current sensor measures a second current value flowing between the anode and the cathode. The control circuit generates diagnostic information related to the vacuum degree of the X-ray tube based on the current ratio of the second current value to the first current value, wherein the second current value is the current value measured by the second current sensor when the first DC voltage and the second DC voltage are applied, and the first current value is the current value measured by the first current sensor when the first DC voltage and the second DC voltage are applied.

[0016] A second aspect of the present invention relates to a diagnostic device of an X-ray generating device having an X-ray tube, the X-ray tube having: an anode and a cathode, the anode and the cathode being sealed inside a vacuum housing, the cathode having an electron source; and an ion collecting conductor mounted on the vacuum housing in a manner of contacting the inner space of the vacuum housing. The diagnostic device comprises a current sensor and a control circuit. The current sensor measures a first current value flowing between the ion collecting conductor and a node, the node supplying a potential for attracting cations in the vacuum housing. The control circuit acquires a measured value of a second current value flowing between the anode and the cathode of the X-ray tube from the X-ray generating device in a state where a first DC voltage serving as the release energy of electrons is applied to the electron source in the X-ray generating device and a second DC voltage for generating an electric field with the anode being a high potential side is applied between the cathode and the anode, and generates diagnostic information related to the vacuum degree of the X-ray tube based on a current ratio of the acquired second current value to the first current value measured by the current sensor.

[0017] A third aspect of the present invention is a diagnostic method for an X-ray generating device, the X-ray generating device having an X-ray tube, the X-ray tube having: an anode and a cathode, the anode and the cathode being sealed inside a vacuum housing, the cathode having an electron source; and an ion collecting conductor mounted on the vacuum housing in a manner contacting the inner space of the vacuum housing, the diagnostic method comprising the following steps: applying a first DC voltage, which becomes the released energy of electrons, to the electron source, and applying a second DC voltage between the cathode and the anode, the second DC voltage being used to generate an electric field with the anode as a high potential side; measuring a first current value flowing between the ion collecting conductor and a node in a state where the first DC voltage and the second DC voltage are applied, the node supplying a potential for attracting cations in the vacuum housing; measuring a second current value flowing between the anode and the cathode of the X-ray tube in a state where the first DC voltage and the second DC voltage are applied; and generating diagnostic information related to the vacuum degree of the X-ray tube based on a current ratio of the measured second current value to the measured first current value.

[0018] Effects of the Invention

[0019] According to the present invention, it is possible to perform X-ray tube degradation diagnosis with high accuracy using a simple configuration. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a block diagram for explaining the configuration of a general X-ray generator shown as a comparative example.

[0021] Figure 2 This is a block diagram illustrating the configuration of the X-ray generator according to this embodiment.

[0022] Figure 3 This is a logarithmic graph showing an example of a Paschen curve.

[0023] Figure 4 1 is a scatter diagram showing actual measurement data of the X-ray tube obtained through vacuum degree diagnosis performed by the X-ray generation device 100 according to the present embodiment.

[0024] Figure 5 yes Figure 4 A magnified view of a local area of ​​the curve graph.

[0025] Figure 6 This is a flowchart for explaining the control process in the diagnosis mode of the X-ray generator according to the present embodiment.

[0026] Figure 7 This is a flowchart for explaining the control process of the DC power supply of the X-ray generator according to the present embodiment. DETAILED DESCRIPTION

[0027] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In addition, the same reference numerals are given to the same or corresponding parts in the drawings, and their description will not be repeated in principle.

[0028] Figure 1 This is a block diagram for explaining the configuration of a general X-ray generator shown as a comparative example.

[0029] Reference Figure 1 X-ray generator 100# of the comparative example includes housing 110, X-ray tube 120, and DC power supplies 160 and 170. X-ray tube 120 is sealed by vacuum housing 121, whereby the interior is kept in a vacuum state.

[0030] The X-ray tube 120 includes a cathode 140 and an anode 150 which are sealed inside a vacuum housing 121. A filament 145 is attached to the surface of the cathode 140. A target 155 is formed at a position on the surface of the anode 150 facing the filament 145.

[0031] The filament 145 is connected to a DC power supply 160. The output voltage Vf of the DC power supply 160 is generally about 10 (V). By energizing the filament 145 with the DC power supply 160, the thermally excited electrons 5 are released from the filament 145. That is, the released energy of the electrons 5 is supplied to the filament 145 by the output voltage Vf of the DC power supply 160.

[0032] The output voltage Vdc of the DC power supply 170 is generally tens of kV to hundreds of kV. A high voltage is applied between the cathode 140 and the anode 150 by the DC power supply 170. As a result, an electric field is formed between the cathode 140 and the anode 150, with the anode 150 side becoming a high potential. The electrons 5 released from the filament 145 are accelerated by the electric field and collide with the target 155, so that the anode 150 generates X-rays.

[0033] X-rays are output to the outside of the X-ray tube 120 via an X-ray irradiation window 135 disposed in an opening 123 of the vacuum housing 121. The X-ray irradiation window 135 is formed using a member having airtightness and high X-ray transmittance (for example, a thin film of beryllium). The X-ray irradiation window 135 is fixed to the X-ray tube 120 (vacuum housing 121) by means of a flange-shaped fixing member 130. The fixing member 130 has an area in contact with the internal space of the vacuum housing 121, and is configured to maintain the sealing of the vacuum housing 121, and fix the X-ray irradiation window 135 to the vacuum housing 121. In addition, the fixing member 130 is electrically connected to the frame 110.

[0034] The external device 500 to which the X-rays are supplied is mounted on the fixing member 130 by screwing or the like. The external device 500 is typically an analytical device or a medical device. Usually, by mounting and fixing the external device 500 on the fixing member 130, the housing 110 and the fixing member 130 are grounded through a ground line shared with the external device 500.

[0035] The X-ray tube 120 is stored inside a housing 110 filled with insulating oil 115. The insulating oil 115 electrically insulates the X-ray tube 120 to which a high voltage is applied from the housing 110 and also has a function of cooling the X-ray tube 120.

[0036] By applying the output voltage Vf of the DC power supply 160 and the output voltage Vdc of the DC power supply 170 to the X-ray tube 120, X-rays are output from the X-ray irradiation window 135 of the X-ray tube 120. The irradiation amount of X-rays changes according to the output voltages of the DC power supply 160 and the DC power supply 170. Specifically, the amount of electrons released from the filament 145 changes according to the output voltage Vf of the DC power supply 160, thereby changing the irradiation amount of X-rays. By configuring the current sensor 180 between the cathode 140 or the anode 150 and the DC power supply 170, the current value Ie (hereinafter also referred to as "emitter current Ie") depending on the amount of electrons can be detected. In addition, the output voltage Vdc of the DC power supply 170 can be changed to change the intensity of the electric field that accelerates the electrons 5, thereby changing the irradiation amount of X-rays.

[0037] In this embodiment, the Figure 1 The X-ray generator 100# of the comparative example shown has a structure that functions to diagnose the vacuum degree inside the X-ray tube 120 in a non-destructive manner.

[0038] Figure 2 This is a block diagram illustrating the configuration of the X-ray generator according to this embodiment.

[0039] Reference Figure 2 The X-ray generating device 100 according to this embodiment and Figure 1 Compared with the X-ray generation device 100 # of the comparative example shown, the difference lies in that a control circuit 190 and a current sensor 210 are further provided.

[0040] The current sensor 210 is electrically connected between the fixing member 130 and the ground node Ng. In addition, since the fixing member 130 is electrically connected to the frame 110, even if the current sensor 210 is connected to the frame 110, the current sensor 210 can be electrically connected between the fixing member 130 and the ground node Ng. As described below, in the diagnosis mode, the current sensor 210 detects the current value Ii.

[0041] The control circuit 190 includes a CPU (Central Processing Unit) 191, a memory 192, an input / output (I / O) circuit 193, and an electronic circuit 194. The CPU 191, the memory 192, and the I / O circuit 193 can mutually transmit and receive signals via a bus 195. The electronic circuit 194 is configured to perform a predetermined operation process by dedicated hardware. The electronic circuit 194 can transmit and receive signals between the CPU 191 and the I / O circuit 193.

[0042] The control circuit 190 receives the mode input, the detection value of the current Ie obtained by the current sensor 180, and the detection value of the current Ii obtained by the current sensor 210, and outputs the diagnostic information indicating the diagnosis result of the vacuum degree in the diagnostic mode. The control circuit 190 can be typically constituted by a microcomputer. In addition, the following mainly describes the processing performed by the control circuit 190 in the diagnostic mode, but Figure 2 The illustrated configuration example does not necessarily mean that a microcomputer dedicated to the diagnostic mode must be configured. For example, in the X-ray generator 100# of the comparative example, the diagnostic mode function described later can be added by adding software or the like to a microcomputer (not shown) configured to control the generation of X-rays, thereby configuring the control circuit 190. Therefore, the X-ray generator 100 involved in the present embodiment can be realized simply by adding the current sensor 210 to the X-ray generator 100# of the comparative example in terms of hardware.

[0043] The X-ray generation device 100 has an X-ray generation mode for irradiating X-rays and a diagnosis mode. The X-ray generation mode and the diagnosis mode can be selected by inputting a mode to the control circuit 190 in response to a button operation or the like by a user.

[0044] The operation of the X-ray generator 100 in the X-ray generation mode is Figure 1 Since the DC power supply 160 is the same as the X-ray generating device 100# of the present invention, the detailed description will not be repeated. Furthermore, in the X-ray generating device 100, in the diagnostic mode, the connection relationship between the DC power supply 160 and the cathode 140 is also the same as that in the X-ray generating mode. Similarly, the output voltage Vdc of the DC power supply 170 is also applied between the cathode 140 and the anode 150 with the same polarity as that in the X-ray generating mode. That is, the DC power supply 160 corresponds to an embodiment of the “first DC power supply”, and the output voltage Vf corresponds to an embodiment of the “first DC voltage”. Similarly, the DC power supply 170 corresponds to an embodiment of the “second DC power supply”, and the output voltage Vdc corresponds to an embodiment of the “second DC voltage”.

[0045] Gas molecules 7 existing in the internal space of the X-ray tube 120 increase due to absorption gas from components of the X-ray tube 120, gas generated by heat generated by electron collision, etc., thereby deteriorating the vacuum degree of the X-ray tube 120. The gas molecules 7 are ionized by the collision electrons 5 and become cations 9.

[0046] The fixing member 130 is electrically connected to the ground node Ng to which the ground potential GND is supplied via the path 200 including the current sensor 210, so that the positive ions 9 generated in the internal space of the X-ray tube 120 are attracted to the fixing member 130. As a result, a current value Ii (hereinafter also referred to as "ion current Ii") depending on the amount of positive ions generated inside the vacuum housing 121 is generated in the path 200. The ion current Ii can be measured by the current sensor 210. At the same time, in the current sensor 180, the emitter current Ie depending on the amount of electron emission from the filament 145 can be measured in the same manner as when X-rays are generated. The value of the emitter current Ie corresponds to the "second current value", and the current sensor 180 corresponds to an embodiment of the "second current sensor". In addition, the value of the ion current Ii corresponds to the "first current value", and the current sensor 210 corresponds to the "first current sensor" or an embodiment of the "current sensor".

[0047] In addition, Figure 2 In the structure of Figure 1 In that case, when the fixing member 130 or the frame 110 is grounded through a path not including the current sensor 210 due to the external device 500 or the like, both ends of the current sensor 210 are at the same potential, and therefore the ion current Ii cannot be measured by the current sensor 210. Therefore, by removing the external device 500 from the fixing member 130 and grounding the fixing member 130 and the frame 110 through the path 200 including the current sensor 210, the ion current Ii can be detected by the current sensor 210. Furthermore, after the external device 500 is removed, a member for shielding X-rays is installed with respect to the X-ray irradiation window 135.

[0048] That is, in Figure 2 In the embodiment, the fixing member 130 corresponds to an embodiment of an "ion collecting conductor", and the ground node Ng corresponds to an embodiment of a "node supplying a potential for attracting positive ions". Thus, without adding a new member (hardware) to the X-ray generating device 100# of the comparative example, an "ion collecting conductor" for vacuum diagnosis can be formed. In addition, as long as the potential is capable of attracting positive ions 9, the current sensor 210 can be electrically connected between the fixing member 130 and a node supplying the potential other than the ground potential GND.

[0049] Generally, the vacuum degree of a confined space is quantitatively evaluated based on the internal pressure of the space. In particular, in an X-ray generating device, the generation of discharges due to the deterioration of the vacuum degree inside the X-ray tube 120 becomes the key point of degradation diagnosis, and it is important to diagnose the deterioration of the vacuum degree in a non-destructive manner before the vacuum degree deteriorates (pressure rises) to such a level.

[0050] exist Figure 3 , an example of a Paschen curve representing discharge characteristics is shown. Figure 3 The horizontal axis represents pressure (Pa), and the vertical axis represents discharge voltage (V). Figure 3 Both the vertical and horizontal axes are logarithmic scales, and in each grid in the figure, the pressure and the discharge voltage are ten times.

[0051] As is known to all, the Paschen curve is obtained based on the Paschen's law which represents the relationship between the discharge voltage and the vacuum degree, the distance between electrodes, and the constant of each gas. As described later, in order to verify the vacuum degree diagnosis involved in this embodiment, the inventors conducted a measurement experiment using an X-ray tube including a deteriorated product in which discharge actually occurred as the object. Figure 3 , Paschen curves 301 to 304 for four gases (helium, nitrogen, water vapor, and air) obtained by analyzing the actual internal gas of an X-ray tube that is the subject of a measurement experiment are shown.

[0052] Reference Figure 3 , it can be understood from Paschen curves 301 to 304 that discharge occurs at different voltages depending on the type of gas. It can be understood from Paschen curves 301 to 303 that discharge occurs in a region above pressure Px (hereinafter also referred to as "discharge pressure Px"), and it can be understood from Paschen curve 304 that discharge occurs in a region above pressure Py. Therefore, in the diagnosis of the vacuum degree of these X-ray tubes, information for quantitatively evaluating the margin relative to the discharge pressure Px in a range lower than the discharge pressure Px is required.

[0053] exist Figure 4 , actual measurement data of the X-ray tube obtained by vacuum degree diagnosis of the X-ray generator 100 according to the present embodiment is shown. Figure 4 1 shows experimental results obtained by setting an X-ray tube used for gas analysis and being an object of measurement in an open state in a vacuum chamber, and measuring the ion current Ii and the emitter current Ie by changing the pressure in the vacuum chamber.

[0054] exist Figure 4The horizontal axis of the logarithmic axis represents the current ratio (Ii / Ie) of the measured emitter current Ie to the ion current Ii. On the other hand, the vertical axis represents the measured value of the pressure P (Pa) in the vacuum chamber. The experiment was performed using multiple X-ray tubes of the same model as the measurement objects. Figure 4 In FIG. 1 , for each X-ray tube, a combination of the current ratio (Ii / Ie) and the measured value of the pressure P is plotted with different marks.

[0055] Depend on Figure 4 It can be understood that in the region where (Ii / Ie) is small, the value of (Ii / Ie) for the same pressure value varies among individual X-ray tubes. On the other hand, it can be understood that if (Ii / Ie) continues to rise, the individual differences are eliminated, and there is a region 300 where (Ii / Ie) for the same pressure value is approximately equal. In this region 300, the slope of the change in pressure P on the logarithmic graph relative to the change in (Ii / Ie) is approximately constant.

[0056] Hereinafter, the region 300 where the characteristic of P with respect to (Ii / Ie) is plotted on a substantially identical straight line on a logarithmic graph regardless of individual differences of X-ray tubes is also referred to as a "diagnosis region 300". It can be understood that within the diagnosis region 300, the internal pressure of the X-ray tube 120 can be quantitatively estimated using (Ii / Ie) regardless of individual differences of X-ray tubes. In addition, the lower limit value Pmin of the pressure range covered by the diagnosis region 300 is Figure 3 1 / 10 of the discharge pressure Px shown 4 times the level.

[0057] Therefore, according to this embodiment, it can be understood that: based on the current ratio (Ii / Ie), 4 ) and above, the increase in pressure toward the discharge pressure Px, i.e., the deterioration of the vacuum degree, is diagnosed in a non-destructive manner.

[0058] exist Figure 5 Shown in Figure 4 An enlarged view of the diagnostic region 300 in the scatter plot of FIG. Figure 5 In the same way, Figure 4 The measurement data of the multiple X-ray tubes shown in FIG. 3 are shown together with the characteristic line 310 obtained as a regression line based on statistical processing. That is, in the diagnosis area 300, the pressure P (Pa) proportional to the k-th power of the current ratio (Ii / Ie) can be estimated by the following formula (1) representing the characteristic line 310.

[0059] P=C·(Ii / Ie) k ……(1)

[0060] In addition, the constant C and the constant k in the formula (1) are fixed values ​​for each model of the X-ray tube 120, and can be treated as the same value in the X-ray tube of the same model. Therefore, the constant C and the constant k can be predetermined by performing a measurement experiment on the model of the X-ray tube 120 assembled in the X-ray generating device 100 in advance. That is, the characteristic line 310 or the formula (1) is equivalent to an embodiment of "a predetermined correspondence relationship between the current ratio and the pressure inside the vacuum housing 121". Information representing the characteristic line 310 or the formula (1) is stored in the memory 192 in advance.

[0061] The control circuit 190 can calculate an estimated pressure value inside the X-ray tube 120 (vacuum housing 121 ) using information representing the characteristic line 310 or equation (1) pre-stored in the memory 192 and the current ratio (Ii / Ie) calculated based on the measured values ​​of the current sensors 180 and 210 .

[0062] For example, by determining in advance a threshold value Pth lower than the discharge pressure Px for the pressure estimate value P calculated in this way, it is possible to display diagnostic information of the vacuum degree indicating whether P>Px. In addition, the threshold value Pth can be set in multiple stages to generate diagnostic information of the vacuum degree in a manner that represents the degree of deterioration of the vacuum degree (the degree of increase in pressure) using multiple levels. Alternatively, as quantitative diagnostic information of the vacuum degree, the pressure difference between the pressure estimate value P and the threshold value Pth or the discharge pressure Px can also be calculated. By converting the pressure into a physical quantity directly related to the discharge generated in the X-ray tube 120, diagnostic information that is easy to form an image of vacuum degree degradation is provided, thereby improving user convenience.

[0063] In addition, the threshold value Jth of the current ratio (Ii / Ie) can be determined in advance in correspondence with the above-mentioned threshold value Pth of the pressure according to the characteristic line 310. Thus, the diagnostic information of the vacuum degree can be generated based on the comparison between the threshold value Jth of a single stage or multiple stages and the measured value of the current ratio (Ii / Ie). Alternatively, as the quantitative diagnostic information of the vacuum degree, the difference between the measured value of the current ratio (Ii / Ie) and the threshold value Jth can also be calculated.

[0064] Figure 6 This is a flowchart for explaining the control process in the diagnosis mode of the X-ray generator according to the present embodiment. Figure 6 The related control processing can be executed by the control circuit 190, for example.

[0065] Reference Figure 6, the control circuit 190 determines whether the diagnosis mode is turned on according to the mode input to the control circuit 190 through step 510. When the diagnosis mode is turned on (when it is determined as "yes" in step 510), the processing of the diagnosis mode after step 520 is started. On the other hand, when the diagnosis mode is turned off, that is, in the X-ray generation mode (when it is determined as "no" in step 510), the processing after step 520 is not started.

[0066] In step 520, the control circuit 190 sets the fixing member 130 as an "ion collecting conductor" to operate the DC power supply 160 and the DC power supply 170. Figure 2 As described in FIG. 1 , electrons released by energizing the filament 145 with the DC power supply 160 are accelerated by the electric field based on the output voltage Vdc of the DC power supply 170. Then, cations 9 generated by collisions between the electrons 5 and the gas molecules 7 are attracted to the ion collecting conductor, thereby generating an ion current Ii.

[0067] In step 520, the control circuit 190 measures the emitter current Ie according to the detection value of the current sensor 180 in step 530, and measures the ion current Ii according to the detection value of the current sensor 210 in step 540. In addition, step 530 and step 540 may be performed in reverse order or simultaneously.

[0068] As described above, when the fixing member 130 that is an ion collecting conductor or the frame 110 that is electrically connected to the fixing member 130 is grounded through a path that does not include the current sensor 210, the measured value of the ion current Ii in step 540 becomes 0. Therefore, together with step 540, step 541 is also performed to compare the measured value of the ion current Ii in step 540 with the determination value ε.

[0069] Preferably, when it is determined that Ii<ε, that is, Ii=0 (when it is determined as "yes" in step 541), a message is output through step 542 to prompt confirmation of the status of the frame 110 and the fixing component 130, specifically, a message is output to prompt confirmation that the frame 110 or the fixing component 130 (ion collector) is not electrically connected to any component other than the current sensor 210, and the processing of the diagnostic mode is temporarily terminated.

[0070] On the other hand, when the control circuit 190 can measure the ion current Ii through step 540 (when it is determined to be "yes" in step 541), the control circuit 190 generates diagnostic information based on the current ratio (Ii / Ie) through step 550. As described above, the diagnostic information can be obtained using the pressure estimation value obtained based on the current ratio (Ii / Ie) and the threshold value Pth ( Figure 5 ) or based on the information of the relationship between the current ratio (Ii / Ie) and the threshold value Jth ( Figure 5 ) information about the relationship between them.

[0071] The control circuit 190 outputs the diagnostic information generated in step 550 through step 560, and terminates the diagnostic mode normally through step 570. The output method of step 560 is not particularly limited. For example, the diagnostic information can be output in the form of text, numbers, illustrations, etc. that can be visually recognized in a specific display screen (not shown), or can be output by turning on and off a light such as a light emitting diode (LED). Alternatively, the diagnostic information can also be output in the form of being sent to a server at a service center via the Internet or the like.

[0072] As described above, according to the X-ray generating device involved in this embodiment, it is possible to diagnose the degradation of the vacuum degree based on the current ratio (Ii / Ie) of the ion current Ii and the emitter current Ie. Here, the vacuum degree of the X-ray tube 120 depends on the number of gas molecules 7 present in the internal space of the X-ray tube 120. Regarding the cations 9, the amount of cations generated by the collision between the gas molecules 7 and the electrons 5 can be quantitatively detected by using the ion current Ii in the same manner as the measurement current of Patent Document 2, but the amount of cations is affected not only by the number of gas molecules 7 present in the internal space of the X-ray tube 120, but also by the amount of electrons emitted from the filament 145.

[0073] Therefore, by using the current ratio (Ii / Ie) of the ion current Ii and the emitter current Ie depending on the amount of electron emission from the filament 145, the number of gas molecules 7 present in the internal space of the X-ray tube 120, that is, the vacuum degree, can be diagnosed with higher accuracy than diagnosis using the ion current Ii alone.

[0074] In addition, in the X-ray generating device 100, the housing 110 and the fixing member 130 can function as an "ion collecting conductor" without changing the connection relationship between the DC power supply 160 and the DC power supply 170 and the cathode 140 and the anode 150 from the X-ray generating mode. That is, there is no need to configure a mechanism for switching the voltage applied to the cathode 140 and the anode 150 between the X-ray generating mode and the diagnostic mode, so that the vacuum degree diagnosis can be performed with a simpler structure than that of Patent Document 2.

[0075] Furthermore, in the X-ray generation device 100 according to the first embodiment, it is preferable that the output voltage Vdc of the DC power supply 170 is switched between the X-ray generation mode and the diagnosis mode.

[0076] Figure 7 1 is a flowchart for explaining the control process of the DC power supply 170 in the X-ray generation device 100 according to the present embodiment. Figure 7The control process shown can be performed by the control circuit 190 .

[0077] Reference Figure 7 , the control circuit 190 determines whether it is in the diagnosis mode in step 610. If it is not in the diagnosis mode, that is, in the X-ray generation mode (when it is determined to be "No" in step 610), the output voltage Vdc of the DC power supply 170 is set to Vh in step 630. Vh is equal to the output voltage Vdc in the X-ray generation device 100# involved in the comparative example, which is about tens (kV) to hundreds (kV).

[0078] On the other hand, in the case of the diagnosis mode (when the determination is "yes" in step 610), the control circuit 190 sets the output voltage Vdc of the DC power supply 170 to Vm in step 620. Vm is a voltage lower than Vh in the X-ray generation mode, and can be set to about 100 (V), for example. Discharge inside the X-ray tube 120 is easily generated by applying a high voltage, so the generation of discharge during diagnosis can be prevented by reducing the output voltage Vdc, thereby stably executing the diagnosis mode. In addition, the generation of unnecessary X-rays can be suppressed.

[0079] By configuring the DC power supply 170 using a power converter having an output voltage changing function, a signal for switching the command value of the output voltage Vdc or the command value of the output voltage Vdc is provided from the control circuit 190 to the DC power supply 170, thereby achieving Figure 7 The output voltage Vdc is shown in FIG.

[0080] In addition, in the present embodiment, the internal structure of the X-ray tube 120 is an example, and as long as it has a cathode including a filament that releases electrons and an anode that generates X-rays by irradiating electrons, the vacuum degree diagnosis based on the measured value of the current ratio of the emitter current Ie and the ion current Ii of the present embodiment can be applied to X-ray tubes of any structure.

[0081] In addition, in this embodiment, the structure of the X-ray generating device 100 with a built-in vacuum diagnosis function is described, but it is also possible to configure a "diagnostic device" in which the current sensor 210 and the control circuit 190 are formed as a single unit. For example, it is possible to configure a diagnostic device in which the current sensor 210 and the control circuit 190 are integrally stored in a frame to be mounted on the fixing member 130 from which the external device 500 has been removed, or the frame 110 electrically connected to the fixing member, thereby forming a diagnostic device for the fixing member 130. Figure 2The path 200 shown. At this time, the control circuit 190 can obtain the measured value of the emitter current Ie obtained by the current sensor 180 of the X-ray generating device 100 in the diagnostic mode, calculate the current ratio (Ii / Ie) between the measured value of the emitter current Ie and the measured value of the ion current Ii obtained by the current sensor 210 on the diagnostic device side to generate diagnostic information.

[0082] Finally, the X-ray generating device disclosed in this embodiment and the diagnostic device and diagnostic method of the X-ray generating device are summarized.

[0083] A first aspect of the present disclosure relates to an X-ray generating device (100). The X-ray generating device includes an X-ray tube (120), a first DC power supply (160), a second DC power supply (170), a first current sensor (210), a second current sensor (180), and a control circuit (190). The X-ray tube includes: a cathode (140) and an anode (150), the cathode (140) and the anode (150) being sealed inside a vacuum housing (121); and an ion collecting conductor (130) being mounted on the vacuum housing in a manner in contact with the internal space of the vacuum housing. The cathode has an electron source (145) for releasing electrons. The anode and the cathode are arranged to face each other, and the anode is configured to emit X-rays by incident electrons released from the electron source. The first DC power supply applies a first DC voltage (Vf) that becomes the released energy of the electrons to the electron source. The second DC power supply applies a second DC voltage (Vdc) between the cathode and the anode, and the second DC voltage (Vdc) is used to generate an electric field with the anode as the high potential side. The first current sensor measures a first current value (Ii) flowing between the ion collecting conductor (130) and a node (Ng), the node (Ng) supplying a potential for attracting cations in the vacuum housing. The second current sensor measures a second current value (Ie) flowing between the anode and the cathode. The control circuit generates diagnostic information related to the vacuum degree of the X-ray tube based on a current ratio (Ii / Ie) of the second current value to the first current value, the second current value being a current value measured by the second current sensor in a state where the first DC voltage and the second DC voltage are applied, and the first current value being a current value measured by the first current sensor in a state where the first DC voltage and the second DC voltage are applied.

[0084] According to the above-mentioned first method, the following function can be provided in the X-ray generating device: by using a current ratio of a first current value depending on the amount of cations generated due to the collision of gas molecules with electrons inside the X-ray tube (vacuum housing) and a second current value depending on the amount of released electrons from the electron source, the number of gas molecules present in the internal space of the X-ray tube, that is, the vacuum degree, can be diagnosed with higher accuracy than diagnosis using the first current value alone.

[0085] In an embodiment of the first mode of the present disclosure, a control circuit (190) includes a storage unit (192). The storage unit stores information indicating a correspondence relationship (310) between a current ratio (Ii / Ie) of an X-ray tube (120) and a pressure inside a vacuum housing, which is predetermined. The diagnostic information is generated using a pressure estimation value calculated using the current ratio and the correspondence relationship based on measurement values ​​of a first current sensor (210) and a second current sensor (180).

[0086] With such a configuration, the diagnostic information that is easy to image the vacuum degree degradation is provided by converting the pressure, which is a physical quantity directly related to the generation of discharge in the X-ray tube, thereby improving the user convenience.

[0087] Alternatively, in an embodiment of the first mode of the present disclosure, the X-ray tube (120) further comprises an X-ray irradiation window (135) and a fixing member (130). The X-ray irradiation window is disposed at an opening of the vacuum housing (121) and is formed of a material that is airtight and allows X-rays to pass through. The fixing member maintains the airtightness of the vacuum housing and fixes the X-ray irradiation window to the vacuum housing. The ion collecting conductor is formed by the fixing member.

[0088] By adopting such a structure, an “ion collecting conductor” for vacuum degree diagnosis can be constructed without adding a new component (hardware).

[0089] In an embodiment of the first mode of the present disclosure, the operation modes of the X-ray generating device (100) include: a first mode for outputting X-rays; and a second mode for performing a diagnosis related to the vacuum degree by generating diagnostic information. The second DC voltage (Vdc) in the second mode is controlled to be a voltage lower than the second DC voltage in the first mode.

[0090] With such a configuration, it is possible to prevent the generation of discharge and stably perform the diagnosis of the vacuum degree, and to suppress the generation of unnecessary X-rays.

[0091] A second aspect of the present invention relates to a diagnostic device of an X-ray generating device (100) having an X-ray tube (120). The X-ray tube (120) comprises: an anode (150) and a cathode (140), the anode (150) and the cathode (140) being sealed inside a vacuum housing (121), the cathode (140) having an electron source (145); and an ion collecting conductor (130) mounted on the vacuum housing in a manner in contact with the internal space of the vacuum housing. The diagnostic device comprises a current sensor (210) and a control circuit (190). The current sensor measures a first current value (Ii) flowing between the ion collecting conductor (130) and a node (Ng), the node (Ng) supplying a potential for attracting positive ions in the vacuum housing. The control circuit (190) obtains a measured value of a second current value (Ie) flowing between the anode and cathode of an X-ray tube from the X-ray generating device in a state where a first DC voltage (Vf) serving as electron release energy is applied to an electron source in an X-ray generating device (100) and a second DC voltage (Vdc) for generating an electric field with the anode as a high potential side is applied between the cathode and the anode, and generates diagnostic information related to the vacuum degree of the X-ray tube based on a current ratio (Ii / Ie) of the obtained second current value and a first current value measured by a current sensor.

[0092] According to the above-mentioned second method, the diagnostic device installed in the X-ray generating device can diagnose the number of gas molecules present in the internal space of the X-ray tube, that is, the vacuum degree, with higher accuracy than the diagnosis using the first current value alone, by using the current ratio of a first current value depending on the amount of cations generated due to the collision of gas molecules with electrons inside the X-ray tube (vacuum shell) and a second current value depending on the amount of released electrons from the electron source.

[0093] A third aspect of the present invention relates to a diagnostic method for an X-ray generating device (100) having an X-ray tube (120). The X-ray tube (120) comprises: an anode (150) and a cathode (140), the anode (150) and the cathode (140) being sealed inside a vacuum housing (121), the cathode (140) having an electron source (145); and an ion collecting conductor (130) mounted on the vacuum housing in a manner contacting the internal space of the vacuum housing. The diagnostic method comprises the following steps: step (520), applying a first DC voltage (Vf) which becomes the released energy of electrons to the electron source, and applying a second DC voltage (Vdc) between the cathode and the anode, wherein the second DC voltage (Vdc) is used to generate an electric field with the anode as the high potential side; step (540), measuring a first current value (Ii) flowing between an ion collecting conductor (130) and a node (Ng) in a state where the first DC voltage and the second DC voltage are applied, wherein the node (Ng) supplies a potential for attracting cations in a vacuum housing; step (530), measuring a second current value (Ie) flowing between the anode and the cathode of the X-ray tube in a state where the first DC voltage and the second DC voltage are applied; and step (550), generating diagnostic information related to the vacuum degree of the X-ray tube based on the current ratio of the measured second current value to the measured first current value.

[0094] According to the third method, in an X-ray generating device, by using a current ratio of a first current value depending on the amount of cations generated due to collision of gas molecules with electrons inside an X-ray tube (vacuum housing) and a second current value depending on the amount of released electrons from an electron source, the number of gas molecules present in the internal space of the X-ray tube, that is, the degree of vacuum, can be diagnosed with higher accuracy than diagnosis using the first current value alone.

[0095] The embodiments disclosed this time should be considered as illustrative in all aspects and not restrictive. The scope of the present invention is indicated by the claims rather than the above description, and is intended to include all modifications within the meaning and scope equivalent to the claims.

[0096] Description of Reference Numerals

[0097] 5: electron; 7: gas molecule; 9: positive ion; 100, 100#: X-ray generating device; 110: frame; 115: insulating oil; 120: X-ray tube; 121: vacuum housing; 123: opening; 130: fixing member; 135: X-ray irradiation window; 140: cathode; 145: filament; 150: anode; 155: target; 160, 170: DC power supply; 180: current sensor (emitter current); 190: control circuit; 191: CPU; 192: memory; 193: I / O circuit; 194: electronic circuit; 195: bus; 200: path; 210: current sensor (ion current); 300: diagnostic area; 301-304: Paschen curve; 310: characteristic line (current ratio-pressure); 500: external device; Ie: emitter current; Ii: ion current; Jth, Pth: threshold; Ng: ground node; P: pressure; Px: discharge pressure; Vdc, Vf: output voltage (DC power supply).

Claims

1. An X-ray generating device, An X-ray tube is provided, the X-ray tube having: a cathode and an anode, the cathode and the anode being sealed inside a vacuum housing; and an ion collecting conductor mounted on the vacuum housing in a manner in contact with the inner space of the vacuum housing, The cathode has an electron source for releasing electrons, The anode is disposed opposite to the cathode, and the anode is configured to emit X-rays when electrons emitted from the electron source are incident thereon. The X-ray generating device comprises: A first DC power supply that applies a first DC voltage serving as release energy of the electrons to the electron source; a second DC power supply, which applies a second DC voltage between the cathode and the anode, wherein the second DC voltage is used to generate an electric field with the anode as a high potential side; a first current sensor for measuring a value of a first current flowing between the ion collecting conductor and a node, the node supplying a potential for attracting positive ions in the vacuum housing; a second current sensor for measuring a value of a second current flowing between the anode and the cathode; as well as a control circuit for generating diagnostic information related to the vacuum degree of the X-ray tube based on a current ratio of the second current value to the first current value, the second current value being a current value measured by the second current sensor in a state where the first DC voltage and the second DC voltage are applied, and the first current value being a current value measured by the first current sensor in a state where the first DC voltage and the second DC voltage are applied, The control circuit includes a storage unit that stores predetermined information indicating a correspondence relationship between the current ratio of the X-ray tube and the pressure inside the vacuum housing. The diagnostic information is generated using a pressure estimation value calculated using the current ratio based on measurement values ​​of the first current sensor and the second current sensor and the correspondence relationship.

2. The X-ray generating device according to claim 1, wherein: The X-ray tube also has: An X-ray irradiation window is disposed at the opening of the vacuum housing and is formed of a material having airtightness and allowing the X-rays to pass therethrough; as well as a fixing member that maintains the airtightness of the vacuum housing and fixes and holds the X-ray irradiation window to the vacuum housing, The ion collecting conductor is constituted by the fixing member.

3. The X-ray generating device according to claim 1, wherein: The operation modes of the X-ray generating device include: outputting a first mode of the X-rays; and a second mode for performing a diagnosis related to the vacuum level by generating the diagnostic information, The second DC voltage in the second mode is controlled to be a voltage lower than the second DC voltage in the first mode.

4. A diagnostic device for an X-ray generating device, the X-ray generating device comprising an X-ray tube, the X-ray tube comprising: an anode and a cathode, the anode and the cathode being sealed inside a vacuum housing, the cathode having an electron source; and an ion collecting conductor mounted on the vacuum housing in a manner contacting with an internal space of the vacuum housing, The diagnostic device comprises: a current sensor that measures a value of a first current flowing between the ion collecting conductor and a node that supplies a potential for attracting positive ions within the vacuum envelope; and a control circuit for acquiring a measured value of a second current value flowing between the anode and the cathode of the X-ray tube from the X-ray generating device in a state where a first DC voltage serving as release energy of electrons is applied to the electron source in the X-ray generating device and a second DC voltage for generating an electric field with the anode being a high potential side is applied between the cathode and the anode, and for generating diagnostic information related to the vacuum degree of the X-ray tube based on a current ratio between the acquired second current value and the first current value measured by the current sensor, in, The control circuit includes a storage unit storing information indicating a predetermined correspondence relationship between the current ratio of the X-ray tube and the pressure inside the vacuum housing. The diagnostic information is generated using a pressure estimation value calculated using the current ratio based on a measurement value of the current sensor and a measurement value of the second current value and the correspondence relationship.

5. A diagnostic method for an X-ray generating device, the X-ray generating device comprising an X-ray tube, the X-ray tube comprising: an anode and a cathode, the anode and the cathode being sealed inside a vacuum housing, the cathode having an electron source; and an ion collecting conductor mounted on the vacuum housing in a manner contacting with an internal space of the vacuum housing, The diagnostic method comprises the following steps: Applying a first DC voltage that becomes electron release energy to the electron source, and applying a second DC voltage between the cathode and the anode, the second DC voltage being used to generate an electric field with the anode being a high potential side; measuring a first current value flowing between the ion collecting conductor and a node in a state where the first DC voltage and the second DC voltage are applied, the node providing a potential for attracting cations in the vacuum envelope; measuring a second current value flowing between the anode and the cathode of the X-ray tube in a state where the first DC voltage and the second DC voltage are applied; as well as generating diagnostic information related to the vacuum degree of the X-ray tube based on a current ratio between the measured second current value and the measured first current value, The diagnostic information is generated using a pressure estimation value calculated using the current ratio based on the measured first current value and the measured second current value and predetermined information of the X-ray tube indicating a correspondence relationship between the current ratio and the pressure inside the vacuum housing.

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