阅读说明：本技术 X射线产生装置以及该x射线产生装置的诊断装置及诊断方法 (X-ray generating apparatus, and diagnostic apparatus and diagnostic method for the same ) 是由 秋山刚志 大桥恒久 中村健一郎 斋藤佑多 于 2019-03-01 设计创作，主要内容包括：X射线管(120)具备：阴极(140)及阳极(150),所述阴极(140)及阳极(150)被密闭于真空外壳(121)的内部；以及集离子导体(130),其以与真空外壳的内部空间接触的方式安装于真空外壳。第一电流传感器(210)测定在集离子导体(130)与节点(Ng)之间流动的第一电流值(Ii),所述节点(Ng)供给用于吸引真空外壳(121)内的阳离子的电位。第二电流传感器(180)测定在阳极(150)与阴极(140)之间流动的第二电流值(Ie)。控制电路(190)基于由第二电流传感器(180)测定出的第二电流值(Ie)与由第一电流传感器(210)测定出的第一电流值(Ii)的电流比(Ii/Ie),来生成与X射线管(120)的真空度相关的诊断信息。(An X-ray tube (120) is provided with: a cathode (140) and an anode (150), wherein the cathode (140) and the anode (150) are sealed in the vacuum housing (121); and an ion-collecting conductor (130) attached to the vacuum housing so as to be in contact with the inner space of the vacuum housing. A first current sensor (210) measures a first current value (Ii) flowing between an ion-collecting conductor (130) and a node (Ng) that supplies a potential for attracting cations within a vacuum enclosure (121). The 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 relating to the degree of vacuum of the X-ray tube (120) on the basis of the 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).)

1. An X-ray generating device is provided,

the X-ray tube is provided with: a cathode and an anode sealed inside the vacuum envelope; and an ion-collecting conductor mounted to the vacuum envelope in contact with an inner space of the vacuum envelope,

the cathode has an electron source for releasing electrons,

the anode is disposed to face the cathode, and the anode is configured to emit X-rays when electrons emitted from the electron source are incident thereon,

the X-ray generation device is provided with:

a first direct-current power supply that applies a first direct-current voltage that becomes the discharge energy of the electrons to the electron source;

a second dc power supply that applies a second dc voltage between the cathode and the anode, the second dc voltage being used to generate an electric field with the anode at a high potential side;

a first current sensor that measures a first current value flowing between the ion-collecting conductor and a node that supplies a potential for attracting cations within the vacuum enclosure;

a second current sensor that measures a second current value flowing between the anode and the cathode; and

and a control circuit that generates diagnostic information relating to the degree of vacuum of the X-ray tube based on a current ratio between a second current value measured by the second current sensor in a state where the first and second dc voltages are applied and a first current value measured by the first current sensor in a state where the first and second dc voltages are applied.

2. The X-ray generation apparatus of claim 1 wherein,

the control circuit includes a storage unit that stores information indicating a correspondence relationship between the current ratio and the pressure inside the vacuum envelope of the X-ray tube, the information being determined in advance,

the diagnostic information is generated using a pressure estimation value calculated using the correspondence relationship and the current ratio based on the measurement values of the first current sensor and the second current sensor.

3. The X-ray generation apparatus of claim 1 wherein,

the X-ray tube further has:

an X-ray irradiation window which is disposed in an opening of the vacuum casing and is formed of a material that is airtight and transmits the X-rays; and

a fixing member that maintains the sealing property of the vacuum housing and fixedly holds the X-ray irradiation window to the vacuum housing,

the ion-collecting conductor is constituted by the fixing member.

4. The X-ray generation apparatus of claim 1 wherein,

the operation mode of the X-ray generation device comprises:

outputting a first pattern of the X-rays; and

a second mode of performing a diagnosis related to the degree of vacuum by generating the diagnostic information,

the second direct-current voltage in the second mode is controlled to be a lower voltage than the second direct-current voltage in the first mode.

5. A diagnostic device for an X-ray generation device, the X-ray generation device comprising an X-ray tube, the X-ray tube comprising: an anode and a cathode hermetically sealed inside the vacuum envelope, the cathode having an electron source; and an ion-collecting conductor mounted to the vacuum envelope in contact with an inner space of the vacuum envelope,

the diagnostic device is provided with:

a current sensor that measures a first current value flowing between the ion-collecting conductor and a node that supplies a potential for attracting cations within the vacuum enclosure; and

a control circuit that 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 generation device in a state where a first dc voltage that becomes emission energy of electrons is applied to the electron source in the X-ray generation device and a second dc voltage for generating an electric field on a high potential side with respect to the anode is applied between the cathode and the anode, and generates diagnostic information relating to a degree of vacuum of the X-ray tube based on a current ratio of the acquired second current value and the first current value measured by the current sensor.

6. A diagnostic method for an X-ray generation device provided with an X-ray tube having: an anode and a cathode hermetically sealed inside the vacuum envelope, the cathode having an electron source; and an ion-collecting conductor mounted to the vacuum envelope in contact with an inner space of the vacuum envelope,

the diagnostic method comprises the following steps:

applying a first direct-current voltage to the electron source, the first direct-current voltage being an energy for discharging electrons, and applying a second direct-current voltage between the cathode and the anode, the second direct-current voltage being for generating an electric field with the anode at a high potential side;

measuring a first current value flowing between the ion-collecting conductor and a node to which a potential for attracting cations in the vacuum envelope is supplied, in a state where the first and second dc voltages are applied;

measuring a second current value flowing between the anode and the cathode of the X-ray tube in a state where the first direct-current voltage and the second direct-current voltage are applied; and

generating diagnostic information relating to the degree of vacuum of the X-ray tube based on a current ratio of the measured second current value to the measured first current value.

Technical Field

The present invention relates to an X-ray generation device, and a diagnostic device and a diagnostic method for the X-ray generation device.

Background

X-ray generation devices are widely used in analysis devices, medical equipment, and the like. Generally, an X-ray generation device is configured to: in an X-ray tube having a vacuum-sealed structure, electrons emitted from a cathode are accelerated by a high voltage applied between the anode and the cathode, and the electrons collide with a target formed on the surface of the anode, thereby generating X-rays.

If the degree of vacuum in the X-ray tube deteriorates due to aging, that is, if the pressure rises, discharge occurs, and replacement is necessary. Therefore, as a method for detecting deterioration of the degree of vacuum in a nondestructive manner and predicting the lifetime, the techniques described in japanese patent laid-open nos. 2006-100174 (patent document 1) and 2016-146288 (patent document 2) have been proposed.

Patent document 1 discloses the following structure: a vacuum measuring unit having an ion gauge ball for an ionization gauge built therein is mounted in a vacuum shell (outer Ware in vacuum: Japanese) of an X-ray tube, thereby measuring the degree of vacuum in the vacuum shell.

Patent document 2 discloses the following technique: the vacuum degree of the X-ray tube is measured by using the correlation between the measurement current and the vacuum degree based on the measurement current flowing between the anode and the cathode when the ionized gas molecules in the X-ray tube are attracted to the anode, with the electric field between the anode and the cathode being set in the opposite direction to the direction when the X-rays are generated.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open No. 2006 and 100174

Patent document 2: japanese patent laid-open publication No. 2016-146288

Disclosure of Invention

Problems to be solved by the invention

However, in the structure of patent document 1, since the vacuum measurement unit is attached to the vacuum casing, there is a possibility that deterioration of the degree of vacuum from the attachment portion and increase of cost due to addition of a new structure may be caused. On the other hand, in patent document 2, although it is not necessary to change the structure of the X-ray tube including the vacuum envelope, a mechanism for applying a voltage between the beam collector 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 the X-rays are generated are newly required in the measurement of the degree of vacuum.

In patent document 2, the gas molecules are quantitatively measured by measuring a current corresponding to the amount of ions generated by the collision of electrons emitted from the cathode with the gas molecules, using the same principle as that of an ionization gauge. Therefore, the measurement current varies depending not only on the molecular weight of the gas present in the X-ray tube but also on the amount of released electrons. On the other hand, in patent document 2, since the life of the X-ray tube is predicted based on the correlation between the measurement current and the vacuum degree, which is obtained in advance, when the amount of electrons released from the cathode when measuring the vacuum degree is different from the amount of electrons released when obtaining the correlation due to the aged change of the apparatus, the variation of the power supply voltage, the individual difference of the X-ray tube, and the like, there is a possibility that an error occurs in the measurement of the vacuum degree, that is, in the diagnosis of the life of the X-ray tube.

The present invention has been made to solve such problems, and an object of the present invention is to perform deterioration diagnosis of an X-ray tube with high accuracy by a simple structure.

Means for solving the problems

A first aspect of the present invention relates to an X-ray generation apparatus. The X-ray generating device is provided with an X-ray tube, a first DC power supply, a second DC power supply, a first current sensor, a second current sensor, and a control circuit. The X-ray tube is provided with: a cathode and an anode sealed inside the vacuum envelope; and an ion-collecting conductor mounted to the vacuum housing so as to be in contact with the inner space of the vacuum housing. The cathode has an electron source that emits electrons. The anode is disposed to face the cathode, and the anode is configured to emit X-rays when electrons emitted from the electron source are incident thereon. The first direct current power supply applies a first direct current voltage to the electron source as discharge energy of the electrons. The second direct-current power supply applies a second direct-current voltage between the cathode and the anode, the second direct-current voltage being used for generating an electric field with the anode as a high potential side. The first current sensor measures a first current value flowing between the ion-collecting conductor and a node that supplies a potential for attracting cations within the vacuum enclosure. The second current sensor measures a second current value flowing between the anode and the cathode. The control circuit generates diagnostic information relating to the degree of vacuum of the X-ray tube based on a current ratio between a second current value measured by the second current sensor in a state where the first DC voltage and the second DC voltage are applied and a first current value measured by the first current sensor in a state where the first DC voltage and the second DC voltage are applied.

A second aspect of the present invention relates to a diagnostic apparatus including an X-ray generation device having an X-ray tube, the X-ray tube including: an anode and a cathode hermetically sealed inside the vacuum envelope, the cathode having an electron source; and an ion-collecting conductor mounted to the vacuum housing so as to be in contact with the inner space of the vacuum housing. The diagnostic device is provided with a current sensor and a control circuit. The current sensor measures a first current value flowing between the ion-collecting conductor and a node that supplies a potential for attracting cations within the vacuum enclosure. 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 generation device in a state where a first DC voltage which becomes emission energy of electrons is applied to the electron source in the X-ray generation device and a second DC voltage for generating an electric field with the anode at a high potential side is applied between the cathode and the anode, and generates diagnostic information relating to the degree of vacuum 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.

A third aspect of the present invention is a diagnostic method for an X-ray generation device including an X-ray tube, the X-ray tube including: an anode and a cathode hermetically sealed inside the vacuum envelope, the cathode having an electron source; and an ion-collecting conductor mounted to the vacuum envelope in contact with an inner space of the vacuum envelope, the diagnostic method comprising the steps of: applying a first direct-current voltage, which is an energy for discharging electrons, to the electron source, and applying a second direct-current voltage, which is for generating an electric field with the anode at a high potential side, between the cathode and the anode; measuring a first current value flowing between the ion-collecting conductor and a node to which a potential for attracting cations in the vacuum envelope is supplied, in a state where a first direct-current voltage and a second direct-current voltage are applied; measuring a second current value flowing between the anode and the cathode of the X-ray tube in a state where the first direct-current voltage and the second direct-current voltage are applied; and generating diagnostic information relating to the degree of vacuum of the X-ray tube based on a current ratio of the measured second current value to the measured first current value.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, it is possible to perform deterioration diagnosis of an X-ray tube with high accuracy by a simple structure.

Drawings

Fig. 1 is a block diagram illustrating a configuration of a general X-ray generation device shown as a comparative example.

Fig. 2 is a block diagram illustrating a configuration of the X-ray generation device according to the present embodiment.

Fig. 3 is a logarithmic graph showing an example of paschen curves.

Fig. 4 is a scatter diagram showing measured data of the X-ray tube obtained by the vacuum degree diagnosis performed by the X-ray generation device 100 according to the present embodiment.

Fig. 5 is an enlarged view of a partial region of the graph of fig. 4.

Fig. 6 is a flowchart illustrating a control process in the diagnostic mode of the X-ray generation device according to the present embodiment.

Fig. 7 is a flowchart illustrating a control process of the dc power supply of the X-ray generation device according to the present embodiment.

Detailed Description

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the following, the same or corresponding portions in the drawings are denoted by the same reference numerals, and description thereof will not be repeated in principle.

Fig. 1 is a block diagram illustrating a configuration of a general X-ray generation device shown as a comparative example.

Referring to fig. 1, an X-ray generation apparatus 100# of the comparative example includes a housing 110, an X-ray tube 120, and dc power supplies 160 and 170. The X-ray tube 120 is sealed by a vacuum envelope 121, and the inside is kept in a vacuum.

The X-ray tube 120 includes a cathode 140 and an anode 150 sealed inside a vacuum casing 121. A filament 145 is mounted on the surface of the cathode 140. A target 155 is formed on the surface of anode 150 at a position facing filament 145.

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). The filament 145 is energized by the dc power supply 160, whereby thermally excited electrons 5 are discharged from the filament 145. That is, the discharge energy of the electrons 5 is supplied to the filament 145 by the output voltage Vf of the dc power supply 160.

The output voltage Vdc of the dc power supply 170 is generally several tens (kV) to several hundreds (kV). A high voltage is applied between the cathode 140 and the anode 150 by the dc power supply 170. Thereby, an electric field having a high potential on the anode 150 side is formed between the cathode 140 and the anode 150. Electrons 5 emitted from the filament 145 are accelerated by the electric field and collide with the target 155, whereby the anode 150 generates X-rays.

The X-rays are output to the outside of the X-ray tube 120 through an X-ray irradiation window 135 disposed in the opening 123 of the vacuum housing 121. The X-ray radiation window 135 is formed by a member (for example, a thin-film-like beryllium) having airtightness and high X-ray transmission power. The X-ray radiation window 135 is fixed to the X-ray tube 120 (vacuum housing 121) by a flange-shaped fixing member 130. The fixing member 130 has a region in contact with the internal space of the vacuum housing 121, and is configured to fix and hold the X-ray radiation window 135 to the vacuum housing 121 while maintaining the sealing property of the vacuum housing 121. The fixing member 130 is electrically connected to the frame 110.

The external device 500 to be supplied with X-rays is attached to the fixing member 130 by screw fixing or the like. The external device 500 is typically an analysis device or a medical device. Generally, when the external device 500 is attached and fixed to the fixing member 130, the housing 110 and the fixing member 130 are grounded via a ground line common to the external device 500.

The X-ray tube 120 is stored inside the housing 110 filled with the 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 cooling function for the X-ray tube 120.

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 X-ray irradiation amount varies according to the output voltages of the dc power supply 160 and the dc power supply 170. Specifically, the amount of electrons emitted from filament 145 changes according to output voltage Vf of dc power supply 160, and the amount of X-ray irradiation changes accordingly. By disposing the current sensor 180 between the cathode 140 or the anode 150 and the dc power supply 170, a current value Ie (hereinafter also referred to as "emitter current Ie") depending on the amount of electrons can be detected. Further, the X-ray irradiation amount can be changed by changing the output voltage Vdc of the dc power supply 170 to change the intensity of the electric field accelerating the electrons 5.

In the present embodiment, a configuration having a function of nondestructively diagnosing the degree of vacuum inside the X-ray tube 120 with respect to the X-ray generation device 100# of the comparative example shown in fig. 1 will be described.

Fig. 2 is a block diagram illustrating a configuration of the X-ray generation device according to the present embodiment.

Referring to fig. 2, the X-ray generation device 100 according to the present embodiment is different from the X-ray generation device 100# of the comparative example shown in fig. 1 in that it further includes a control circuit 190 and a current sensor 210.

The current sensor 210 is electrically connected between the fixed member 130 and the ground node Ng. Further, since the fixing member 130 is electrically connected to the housing 110, even if the current sensor 210 is connected to the housing 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.

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 transmit and receive signals to and from each other via the bus 195. The electronic circuit 194 is configured to execute predetermined arithmetic processing by dedicated hardware. The electronic circuit 194 can transmit and receive signals to and from the CPU 191 and the I/O circuit 193.

The control circuit 190 accepts a mode input, and a detection value of the current Ie obtained by the current sensor 180 and a detection value of the current Ii obtained by the current sensor 210, and outputs diagnostic information indicating a diagnostic result of the vacuum degree in the diagnostic mode. The control circuit 190 can be representatively configured by a microcomputer. In the following, although the processing performed by the control circuit 190 in the diagnostic mode will be mainly described, the configuration example shown in fig. 2 does not mean that a microcomputer dedicated to the diagnostic mode is necessarily disposed. For example, the control circuit 190 can be configured by adding software to a microcomputer (not shown) provided for controlling the X-ray generation in the X-ray generation device 100# of the comparative example and adding a diagnostic mode function described later. Therefore, the X-ray generation apparatus 100 according to the present embodiment can be realized only by additionally disposing the current sensor 210 to the X-ray generation apparatus 100# of the comparative example in terms of hardware.

The X-ray generation apparatus 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 performing a mode input to the control circuit 190 in response to a button operation or the like by the user.

The operation of the X-ray generation apparatus 100 in the X-ray generation mode is the same as that of the X-ray generation apparatus 100# in fig. 1, and therefore detailed description thereof will not be repeated. In the X-ray generation apparatus 100, the connection relationship between the dc power supply 160 and the cathode 140 in the diagnosis mode is also the same as in the X-ray generation 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 in the X-ray generation mode. That is, the dc power supply 160 corresponds to one embodiment of the "first dc power supply", and the output voltage Vf corresponds to one embodiment of the "first dc voltage". Likewise, the dc power supply 170 corresponds to an embodiment of "second dc power supply", and the output voltage Vdc corresponds to an embodiment of "second dc voltage".

The gas molecules 7 existing in the internal space of the X-ray tube 120 increase due to absorption gas coming out of the components of the X-ray tube 120, gas generated by heat generated by electron collision, and the like, whereby the degree of vacuum of the X-ray tube 120 deteriorates. The gas molecules 7 change to cations 9 when ionized by the collision electrons 5.

The fixed member 130 is electrically connected to the ground node Ng supplied with the ground potential GND through the path 200 including the current sensor 210, and therefore the positive ions 9 generated in the internal space of the X-ray tube 120 are attracted to the fixed member 130. Thereby, in the path 200, a current value Ii (hereinafter also referred to as "ion current Ii") depending on the amount of cations generated inside the vacuum envelope 121 is generated. The ion current Ii can be measured by the current sensor 210. Meanwhile, in the current sensor 180, the emitter current Ie depending on the amount of electrons released from the filament 145 can be measured, as in the case of generating X-rays. The value of the emitter current Ie corresponds to a "second current value", and the current sensor 180 corresponds to one embodiment of a "second current sensor". In addition, the value of the ion current Ii corresponds to a "first current value", and the current sensor 210 corresponds to a "first current sensor" or an embodiment of a "current sensor".

In the configuration of fig. 2, when the fixed member 130 or the housing 110 is grounded through a path not including the current sensor 210 by the external device 500 or the like as shown in fig. 1, 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 detaching the external device 500 from the fixed member 130 and grounding the fixed member 130 and the housing 110 through the path 200 including the current sensor 210, the ion current Ii can be detected by the current sensor 210. After the external device 500 is detached, a member for shielding X-rays is attached to the X-ray radiation window 135.

That is, in fig. 2, the fixing member 130 corresponds to one example of the "ion-collecting conductor", and the ground node Ng corresponds to one example of the "node supplying a potential for attracting positive ions". Thus, the "ion-collecting conductor" for vacuum degree diagnosis can be configured without adding a new component (hardware) to the X-ray generation device 100# of the comparative example. The current sensor 210 can be electrically connected between the fixed member 130 and a node to which a potential other than the ground potential GND is supplied, as long as the potential can attract the positive ions 9.

Generally, the degree of vacuum of a closed space is quantitatively evaluated based on the internal pressure of the space. In particular, in the X-ray generation device, the generation of discharge due to the deterioration of the vacuum degree in the X-ray tube 120 is the main point of the deterioration diagnosis, and it is important to diagnose the deterioration of the vacuum degree in a nondestructive manner before the deterioration of the vacuum degree (pressure rise) reaches such a level.

Fig. 3 shows an example of a paschen curve representing the discharge characteristic. In fig. 3, the horizontal axis represents pressure (Pa) and the vertical axis represents discharge voltage (V). In fig. 3, both the vertical axis and the horizontal axis are logarithmic scales, and the pressure and the discharge voltage are ten times as large in each grid.

As is well known, the paschen curve is obtained by paschen's law which expresses the relationship between the discharge voltage and the degree of vacuum, the distance between electrodes, and the constants for each gas. As described later, in order to verify the vacuum degree diagnosis according to the present embodiment, the inventors performed measurement experiments for an X-ray tube including a deteriorated product in which discharge actually occurred. Fig. 3 shows paschen curves 301 to 304 for four gases (helium, nitrogen, water vapor, and atmospheric air) obtained by analyzing the actual internal gas of the X-ray tube to be subjected to the measurement experiment.

Referring to FIG. 3, from Paschen curve 301 to Paschen curve 304, it can be understood that: the discharge is generated at different voltages depending on the kind of gas. The paschen curve 301 to paschen curve 303 are understood to generate discharge in a region where the pressure is equal to or higher than Px (hereinafter, also referred to as "discharge pressure Px"), and the paschen curve 304 is understood to generate discharge in a region where the pressure is equal to or higher than Py. Therefore, in the diagnosis of the degree of vacuum for these X-ray tubes, information for quantitatively evaluating the margin with respect to the discharge pressure Px in a range on the lower pressure side than the discharge pressure Px is required.

Fig. 4 shows measured data of the X-ray tube obtained by the vacuum degree diagnosis of the X-ray generation device 100 according to the present embodiment. Fig. 4 shows an experimental result obtained by measuring the ion current Ii and the emitter current Ie while changing the pressure in the vacuum chamber in a state where an X-ray tube to be measured, which is an open measurement target for gas analysis, is installed in the vacuum chamber.

The abscissa of fig. 4 represents a current ratio (Ii/Ie) of the emitter current Ie and the ion current Ii measured on a logarithmic axis. On the other hand, the vertical axis represents the measured value of the pressure p (pa) in the vacuum chamber on the logarithmic axis. An experiment was performed using a plurality of X-ray tubes of the same model as the measurement target, and in fig. 4, combinations of current ratios (Ii/Ie) and actual measurement values of pressure P are plotted with different markers for each X-ray tube.

As can be understood from fig. 4: in a small region of (Ii/Ie), the value of (Ii/Ie) for the same pressure value is biased by individual X-ray tubes. On the other hand, it is understood that: if (Ii/Ie) rises, the individual difference is eliminated, and there is a region 300 where (Ii/Ie) is substantially equal for the same pressure value. Within this region 300, the slope of the change in pressure P on the logarithmic graph relative to the change in (Ii/Ie) is substantially fixed.

Hereinafter, the characteristic of P with respect to (Ii/Ie) will be plotted on a logarithmic graph regardless of individual differences of the X-ray tubeThis region 300 on the substantially same straight line is also referred to as a "diagnostic region 300". It can be understood that: within the diagnostic region 300, (Ii/Ie) can be used to quantitatively estimate the internal pressure of the X-ray tube 120 regardless of individual differences of the X-ray tube. The lower limit Pmin of the pressure range covered by the diagnostic region 300 is 1/10 of the discharge pressure Px shown in fig. 3⁴The order of the multiples.

Thus, according to the present embodiment, it can be understood that: can be based on the current ratio (Ii/Ie) at Px (1/10)⁴) In the above pressure range, the increase in pressure toward the discharge pressure Px, that is, the deterioration in the degree of vacuum is diagnosed in a nondestructive manner.

An enlarged view of the diagnostic region 300 in the scatter plot of fig. 4 is shown in fig. 5. In fig. 5, measurement data of a plurality of X-ray tubes shown in fig. 4 are plotted with the same reference numerals, and a characteristic line 310 obtained as a regression line by statistical processing is also indicated. That is, in the diagnostic region 300, the pressure p (pa) proportional to the k-power of the current ratio (Ii/Ie) can be estimated by the following expression (1) representing the characteristic line 310.

P＝C·(Ii/Ie)^k……(1)

The constant C and the constant k in the equation (1) are fixed values for each model of the X-ray tube 120, and can be handled as the same value in the same model of X-ray tube. Therefore, the constant C and the constant k can be determined in advance by performing a measurement experiment in advance for the X-ray tube 120 of the type incorporated in the X-ray generation apparatus 100. That is, the characteristic line 310 or the equation (1) corresponds to one example of "a predetermined correspondence relationship between the current ratio and the pressure inside the vacuum envelope 121". Information indicating the characteristic line 310 or the equation (1) is stored in the memory 192 in advance.

The control circuit 190 can calculate the estimated pressure value inside the X-ray tube 120 (vacuum envelope 121) using the information indicating the characteristic line 310 or equation (1) stored in advance in the memory 192 and the current ratio (Ii/Ie) calculated from the measurement values of the current sensor 180 and the current sensor 210.

For example, by determining a threshold Pth lower than the discharge pressure Px in advance for the thus calculated pressure estimation value P, it is possible to show diagnostic information indicating whether or not P > Px vacuum degree is present. Further, the threshold Pth may be set in a plurality of stages, and the diagnostic information of the vacuum degree may be generated so that the degree of deterioration of the vacuum degree (the degree of increase in pressure) is expressed by a plurality of levels. Alternatively, as diagnostic information of a quantitative degree of vacuum, the pressure difference between the pressure estimation value P and the threshold Pth or the discharge pressure Px can also be calculated. By converting the pressure into a physical quantity directly related to the discharge generation in the X-ray tube 120, diagnostic information that facilitates the formation of an image with degraded vacuum is provided, thereby improving user convenience.

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

Fig. 6 is a flowchart illustrating a control process in the diagnostic mode of the X-ray generation device according to the present embodiment. The control processing in fig. 6 can be executed by the control circuit 190, for example.

Referring to fig. 6, the control circuit 190 determines whether the diagnostic mode is turned on according to the mode input to the control circuit 190 through step 510. When the diagnostic mode is turned on (yes at step 510), the process of the diagnostic mode after step 520 is started. On the other hand, when the diagnostic mode is off, that is, in the X-ray generation mode (when the determination at step 510 is no), the processing at and after step 520 is not started.

In step 520, the control circuit 190 sets the fixing member 130 to the "ion collecting conductor" to operate the dc power supply 160 and the dc power supply 170. As a result, as described in fig. 2, electrons emitted by the dc power supply 160 energizing the filament 145 are accelerated by an electric field based on the output voltage Vdc of the dc power supply 170. Then, positive ions 9 generated by the collision of the electrons 5 with the gas molecules 7 are attracted to the ion-collecting conductor described above, thereby generating an ion current Ii.

In the state of step 520, the control circuit 190 measures the emitter current Ie from the detection value of the current sensor 180 in step 530, and measures the ion current Ii from the detection value of the current sensor 210 in step 540. Further, steps 530 and 540 may be performed in reverse order, or may be performed simultaneously.

As described above, when the fixing member 130 serving as the ion-collecting conductor or the housing 110 electrically connected to the fixing member 130 is grounded through the path not including the current sensor 210, the measured value of the ion current Ii becomes 0 in step 540. Therefore, step 541 of comparing the measurement value of the ion current Ii in step 540 with the determination value ∈ is executed together with step 540.

Preferably, when it is determined that Ii < epsilon, that is, Ii is 0 (when it is determined to be yes in step 541), a message for prompting confirmation of the state of the housing 110 and the fixed member 130, specifically, a message for prompting confirmation that the housing 110 or the fixed member 130 (ion-collecting conductor) is not electrically connected to a member other than the current sensor 210 is output in step 542, and the process in the diagnostic mode is temporarily ended.

On the other hand, when the ion current Ii can be measured in step 540 (when the determination in step 541 is yes), the control circuit 190 generates diagnostic information based on the current ratio (Ii/Ie) in step 550. As described above, the diagnostic information can use information based on the relationship between the pressure estimation value obtained from the current ratio (Ii/Ie) and the threshold Pth (fig. 5), or information based on the relationship between the current ratio (Ii/Ie) and the threshold Jth (fig. 5).

The control circuit 190 outputs the diagnostic information generated in step 550 through step 560, and normally ends the diagnostic mode through step 570. The output mode of step 560 is not particularly limited. For example, the diagnostic information may be output using characters, numerals, illustrations, and the like that can be visually recognized on a specific display screen (not shown), or may be output by turning on or off a lamp such as a Light Emitting Diode (LED). Alternatively, the diagnostic information may be output to a server of the service center via the internet or the like.

As described above, according to the X-ray generation device of the present embodiment, deterioration of the vacuum degree can be diagnosed based on the current ratio (Ii/Ie) of the ion current Ii and the emitter current Ie. Here, the degree of vacuum of the X-ray tube 120 depends on the number of gas molecules 7 existing in the internal space of the X-ray tube 120. As for the cations 9, the amount of cations generated by the collision of the gas molecules 7 with the electrons 5 can be quantitatively detected by the ion current Ii in the same manner as the measurement current of patent document 2, but the amount of cations is influenced 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 released from the filament 145.

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

In the X-ray generation device 100, the frame 110 and the fixing member 130 can function as "ion collecting conductors" 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 generation mode. That is, since it is not necessary to provide a mechanism for switching the applied voltages to the cathode 140 and the anode 150 between the X-ray generation mode and the diagnosis mode, it is possible to diagnose the degree of vacuum with a simpler configuration than patent document 2.

In the X-ray generation device 100 according to embodiment 1, it is preferable that the output voltage Vdc of the dc power supply 170 be switched between the X-ray generation mode and the diagnosis mode.

Fig. 7 is a flowchart illustrating a control process of the dc power supply 170 in the X-ray generation device 100 according to the present embodiment. The control process shown in fig. 7 can be executed by the control circuit 190.

Referring to fig. 7, the control circuit 190 determines whether or not the diagnosis mode is selected in step 610. If the diagnosis mode is not the one, that is, if the X-ray generation mode is the one (no in step 610), the output voltage Vdc of the dc power supply 170 is set to Vh in step 630. Vh is about several tens (kV) to several hundreds (kV) equal to the output voltage Vdc in the X-ray generation apparatus 100# according to the comparative example.

On the other hand, in the case of the diagnosis mode (when the determination result in step 610 is yes), control circuit 190 sets output voltage Vdc of 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, for example, about 100 (V). The discharge inside the X-ray tube 120 is liable to be generated by applying a high voltage, and therefore, the generation of the discharge at the time of diagnosis can be prevented by lowering the output voltage Vdc to stably perform the diagnosis mode. In addition, generation of unnecessary X-rays can be suppressed.

By configuring dc power supply 170 with a power converter having an output voltage changing function, control of output voltage Vdc shown in fig. 7 can be realized by supplying a signal for switching the command value of output voltage Vdc or the command value of output voltage Vdc from control circuit 190 to dc power supply 170.

In the present embodiment, the internal structure of the X-ray tube 120 is an example, and it is sufficient to have a cathode including a filament that emits electrons and an anode that generates X-rays by irradiating electrons, and the vacuum degree diagnosis based on the measured value of the current ratio of the emitter current Ie and the ion current Ii in the present embodiment can be applied to an X-ray tube having any structure.

In the present embodiment, the configuration of the X-ray generation device 100 incorporating the diagnostic function of the degree of vacuum is described, but a "diagnostic device" in which the current sensor 210 and the control circuit 190 are formed as a single unit may be configured. For example, the following configurations are possible: the diagnostic apparatus in which the current sensor 210 and the control circuit 190 are integrally stored in the housing is attached to the fixing member 130 from which the external device 500 is detached or the housing 110 electrically connected to the fixing member, thereby forming the path 200 shown in fig. 2 for the fixing member 130. In this case, the control circuit 190 can acquire the measured value of the emitter current Ie obtained by the current sensor 180 of the X-ray generation apparatus 100 in the diagnosis mode, and 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 diagnosis apparatus side to generate the diagnosis information.

Finally, the X-ray generation device disclosed in the present embodiment, and a diagnostic device and a diagnostic method for the X-ray generation device are summarized.

A first aspect of the present disclosure relates to an X-ray generation apparatus (100). The X-ray generation device is provided with an X-ray tube (120), a first DC power supply (160) and a second DC power supply (170), a first current sensor (210) and a second current sensor (180), and a control circuit (190). The X-ray tube is provided with: a cathode (140) and an anode (150), wherein the cathode (140) and the anode (150) are sealed in the vacuum housing (121); and an ion-collecting conductor (130) attached to the vacuum housing so as to be in contact with the inner space of the vacuum housing. The cathode has an electron source (145) for emitting electrons. The anode is disposed to face the cathode, and the anode is configured to emit X-rays when electrons emitted from the electron source are incident thereon. The first direct current power supply applies a first direct current voltage (Vf) to the electron source, which becomes the discharge energy of the electrons. The second direct-current power supply applies a second direct-current voltage (Vdc) between the cathode and the anode for generating an electric field with the anode as a high potential side. The first current sensor measures a first current value (Ii) flowing between the ion-collecting conductor (130) and a node (Ng) which supplies a potential for attracting cations within the vacuum envelope. The second current sensor measures a second current value (Ie) flowing between the anode and the cathode. The control circuit generates diagnostic information relating to the degree of vacuum of the X-ray tube based on a current ratio (Ii/Ie) between a second current value measured by the second current sensor in a state where the first DC voltage and the second DC voltage are applied and a first current value measured by the first current sensor in a state where the first DC voltage and the second DC voltage are applied.

According to the first aspect, the X-ray generation device can include the following functions: the number of gas molecules existing in the internal space of the X-ray tube, that is, the degree of vacuum is diagnosed with higher accuracy than diagnosis using the first current value alone by using a current ratio of a first current value depending on the amount of positive ions generated due to collision of gas molecules with electrons inside the X-ray tube (vacuum envelope) to a second current value depending on the amount of released electrons from the electron source.

In an embodiment according to a first aspect of the present disclosure, a control circuit (190) includes a storage unit (192). Information indicating a correspondence (310) between a current ratio (Ii/Ie) of an X-ray tube (120) and the pressure inside the vacuum housing, which is determined in advance, is stored in a storage unit. The diagnostic information is generated using a pressure estimation value calculated using a current ratio and a correspondence relationship based on measurement values of the first current sensor (210) and the second current sensor (180).

With such a configuration, it is possible to provide diagnostic information that facilitates formation of an image of a deteriorated vacuum degree in terms of pressure that is a physical quantity directly related to discharge generation in the X-ray tube, thereby improving user convenience.

Alternatively, in an embodiment according to a first aspect of the present disclosure, the X-ray tube (120) further includes an X-ray irradiation window (135) and a fixing member (130). The X-ray irradiation window is disposed in an opening of the vacuum housing (121), and is formed of a material that is airtight and transmits X-rays. The fixing member maintains the sealing performance of the vacuum casing and fixes and holds the X-ray irradiation window on the vacuum casing. The ion-collecting conductor is constituted by a fixing member.

With such a configuration, the "ion collector conductor" for vacuum degree diagnosis can be configured without adding a new component (hardware).

In addition, in an embodiment according to a first aspect of the present disclosure, an operation mode of an X-ray generation device (100) includes: a first mode of outputting X-rays; and a second mode for performing a diagnosis related to the degree of vacuum by generating the diagnosis information. The second direct current voltage (Vdc) in the second mode is controlled to be lower than the second direct current voltage in the first mode.

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

A second aspect of the present invention relates to a diagnostic apparatus including an X-ray generation apparatus (100) having an X-ray tube (120). An X-ray tube (120) is provided with: an anode (150) and a cathode (140), wherein the anode (150) and the cathode (140) are hermetically sealed inside a vacuum housing (121), and the cathode (140) has an electron source (145); and an ion-collecting conductor (130) attached to the vacuum housing so as to be in contact with the inner space of the vacuum housing. The diagnostic device is provided with 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) which supplies a potential for attracting cations within the vacuum enclosure. A control circuit (190) acquires a measured value of a second current value (Ie) flowing between an anode and a cathode of an X-ray tube from an X-ray generation device in a state where a first direct-current voltage (Vf) which becomes emission energy of electrons is applied to an electron source and a second direct-current voltage (Vdc) for generating an electric field with the anode at a high potential side is applied between the cathode and the anode in the X-ray generation device (100), and generates diagnostic information relating to the degree of vacuum of the X-ray tube based on a current ratio (Ii/Ie) between the acquired second current value and the first current value measured by a current sensor.

According to the second aspect described above, the diagnostic device mounted on the X-ray generation device can diagnose the number of gas molecules present in the internal space of the X-ray tube, that is, the degree of vacuum, with higher accuracy than diagnosis using the first current value alone, by using the current ratio of the first current value depending on the amount of positive ions generated due to the collision of the gas molecules with electrons inside the X-ray tube (vacuum envelope) to the second current value depending on the amount of released electrons from the electron source.

A third aspect of the present invention relates to a diagnostic method for an X-ray generation device (100) provided with an X-ray tube (120). An X-ray tube (120) is provided with: an anode (150) and a cathode (140), wherein the anode (150) and the cathode (140) are hermetically sealed inside a vacuum housing (121), and the cathode (140) has an electron source (145); and an ion-collecting conductor (130) attached to the vacuum housing so as to be in contact with the inner space of the vacuum housing. The diagnostic method comprises the following steps: a step (520) of applying a first direct-current voltage (Vf) to the electron source, the first direct-current voltage being an energy for discharging electrons, and applying a second direct-current voltage (Vdc) between the cathode and the anode, the second direct-current voltage (Vdc) being for generating an electric field having the anode on a high potential side; a step (540) of measuring a first current value (Ii) flowing between the ion-collecting conductor (130) and a node (Ng) that supplies a potential for attracting cations in the vacuum enclosure, in a state where a first direct-current voltage and a second direct-current voltage are applied; a step (530) of 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 a step (550) of generating diagnostic information relating to the degree of vacuum of the X-ray tube on the basis of the current ratio between the measured second current value and the measured first current value.

According to the third aspect described above, in the X-ray generation device, by using the current ratio of the first current value depending on the amount of positive ions generated due to the collision of gas molecules with electrons inside the X-ray tube (vacuum envelope) to the second current value depending on the amount of released electrons from the electron source, the number of gas molecules existing 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.

The embodiments disclosed herein are to be considered in all respects as illustrative and not restrictive. The scope of the present invention is indicated by the appended claims rather than by the foregoing description, and all changes that come within the meaning and range of equivalency of the claims are intended to be embraced therein.

Description of the reference numerals

5: electrons; 7: gas molecules; 9: a cation; 100. 100 #: an X-ray generating device; 110: a frame body; 115: insulating oil; 120: an X-ray tube; 121: a vacuum enclosure; 123: an opening part; 130: a fixing member; 135: an X-ray irradiation window; 140: a cathode; 145: a filament; 150: an anode; 155: a target; 160. 170: a direct current power supply; 180: current sensor (emitter current); 190: a control circuit; 191: a CPU; 192: a memory; 193: an I/O circuit; 194: an electronic circuit; 195: a bus; 200: a path; 210: current sensors (ionic current); 300: a diagnostic region; 301-304: paschen curves; 310: characteristic line (current ratio-pressure); 500: an external device; ie: an emitter current; ii: an ion current; jth, Pth: a threshold value; ng: a ground node; p: pressure; px: a discharge pressure; vdc, Vf: output voltage (dc power supply).