JP5237002B2 - X-ray generator and filament determination method - Google Patents

Description

  The present invention relates to an X-ray generator used as an X-ray source in an X-ray nondestructive inspection or the like, and a filament determination method implemented in such an X-ray generator.

In the X-ray generator of the above technical field, different types of filaments may be attached to the electron gun depending on the purpose. For example, when the resolution of the X-ray image should be increased, a filament made of lanthanum boride (hereinafter referred to as “LaB ₆ filament”) is used as the electron emission member, and when a high resolution of the X-ray image is not required, The discharge member uses a filament made of tungsten (hereinafter referred to as “W filament”).

  However, since the setting conditions in the X-ray generator differ for each type of filament, the type of filament attached to the electron gun is mistakenly recognized, and the X-ray generator is operated under the incorrect setting condition. As a result, an optimum X-ray image cannot be obtained, and in the worst case, the filament may burn out.

In order to solve such a problem, Patent Document 1 focuses on the fact that the resistance value of the filament differs for each type of filament, and the filament is based on the voltage value generated when a constant current is passed through the filament. An X-ray generation apparatus for determining the type of the is described.
Japanese Patent No. 3659547

However, the X-ray generator described in Patent Document 1 has the following problems. That is, since the resistance value of the filament changes depending on the difference in shape, installation state, individual differences, etc., between the filaments having a originally small difference in resistance value (for example, LaB ₆ filament and W filament), the type of filament May be erroneously determined.

  Therefore, the present invention has been made in view of such circumstances, and provides an X-ray generator and a filament determination method capable of accurately determining the type of filament attached to an electron gun. Objective.

  In order to achieve the above object, an X-ray generator according to the present invention is an X-ray generator that causes an electron beam emitted from an electron gun to enter a target and emit X-rays from the target. When the first filament is a first filament, electrons are emitted, and when the filament is a second filament, a predetermined voltage is applied to the filament so that electrons are not emitted. When a predetermined current flowing when detected is detected, it is determined that the filament is the first filament, and when a predetermined current is not detected, it is determined that the filament is the second filament. It is characterized by.

  In this X-ray generator, when the filament is the first filament, electrons are emitted, and when the filament is the second filament, no electrons are emitted. Whether it is a second filament or not is determined. Thus, since the type of filament can be determined under conditions closer to those during normal operation of the X-ray generator, erroneous determination is prevented and the type of filament attached to the electron gun is accurately determined. It becomes possible.

  In the X-ray generator according to the present invention, when a predetermined voltage is applied to the filament and a predetermined current is detected in the middle of boosting the tube voltage to be applied between the filament and the target, the filament Is determined to be the first filament, and if a predetermined current is not detected, it is preferable to determine that the filament is the second filament. As a result, the filament can be determined before the actual operating state is reached, so that the filament can be determined quickly and efficiently.

  In the X-ray generator according to the present invention, the predetermined current is preferably a current that flows in a predetermined portion of the electron path through which the electron beam emitted from the electron gun passes. Thus, by detecting the electrons actually emitted into the electron path, the type of filament attached to the electron gun can be determined with higher accuracy.

  In the X-ray generator according to the present invention, the predetermined current is preferably a tube current flowing from the power supply unit to the filament. As described above, by detecting the electrons supplied to the filament from the power supply unit in order to emit electrons, the type of the filament attached to the electron gun can be determined with higher accuracy.

  In the X-ray generator according to the present invention, the predetermined current is preferably a current flowing through the target. Thus, by detecting the electrons that have actually reached the target, the type of filament attached to the electron gun can be determined more accurately.

  The filament determination method according to the present invention is a filament determination method implemented in an X-ray generator that causes an electron beam emitted from an electron gun to enter a target and emits X-rays from the target. When the first filament is a first filament, electrons are emitted, and when the filament is a second filament, a predetermined voltage is applied to the filament so that electrons are not emitted. When a predetermined current that flows or a predetermined X-ray to be emitted is detected, it is determined that the filament is the first filament, and when a predetermined current and a predetermined X-ray are not detected Is characterized in that the filament is determined to be the second filament.

  According to this filament determination method, not only the predetermined current that flows when electrons are emitted from the filament, but also the predetermined X-rays emitted at that time, under conditions closer to the normal operation of the X-ray generator. Since the type of filament can be determined based on the detection result, the type of filament attached to the electron gun can be accurately determined.

  According to the present invention, the type of filament attached to the electron gun can be accurately determined.

  DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. In addition, in each figure, the same code | symbol is attached | subjected to the same or an equivalent part, and the overlapping description is abbreviate | omitted.

  FIG. 1 is a configuration diagram of an embodiment of an X-ray generator according to the present invention. As shown in FIG. 1, the X-ray generator 1 causes an electron beam E emitted from an electron gun 2 to enter a target 5 and makes it forward from the target 5 (the front side in the traveling direction of the electron beam E is “front”). This is a transmission X-ray generator that emits X-rays on the rear side of the rear side. The X-ray generator 1 includes an X-ray tube 10 called an open type in which the filament F of the electron gun 2 can be replaced, a high-voltage power supply unit 20 that applies a high voltage to the X-ray tube 10, and a high-voltage power supply unit 20. And a PC (personal computer) 41 as an operation unit connected to the control unit 30. An X-ray detection device 50 that detects X-rays emitted from the X-ray tube 10 is disposed in front of the X-ray tube 10.

  In the electron gun 2, a grid electrode 3 that controls the amount of electrons emitted from the filament F toward the target 5 (in other words, the tube current value) is disposed in front of the filament F. In the vacuum chamber of the X-ray tube 10, on the electron path 7 through which the electron beam E emitted from the electron gun 2 passes, an anode portion 4 for accelerating the electron beam E, and an alignment for adjusting the traveling direction of the electron beam E An electrode 6, an aperture portion 8 for confirming the traveling direction of the electron beam E, and an electromagnetic coil 9 for focusing the electron beam E on the target 5 are sequentially arranged from the rear side.

  The aperture unit 8 is connected to an aperture current measuring circuit 42 that measures the aperture current flowing through the aperture unit 8 when the electron beam E is incident. The traveling direction of the electron beam E is adjusted by the alignment electrode 6 so that the aperture current measured by the aperture current measuring circuit 42 becomes a small value, and the traveling direction of the electron beam E is the center of the electron passage hole of the aperture portion 8. It is made coincident with the line (that is, the center line of the electron path 7). The target 5 is connected to a target current measuring circuit 43 that measures the target current flowing through the target 5 when the electron beam E is incident. A grid voltage (a potential difference between the filament F and the grid electrode 3) and a filament voltage (a voltage for discharging thermoelectrons from the filament F and a potential difference between both ends of the filament F) are measured by the target current measurement circuit 43. The target current to be adjusted is adjusted to a desired value.

  The high voltage power supply unit 20 includes a high voltage generation unit 21 and a power supply control unit 22. The high voltage generation unit 21 includes a high voltage circuit 23 that applies a tube voltage to the filament F, a filament voltage generation circuit 24 that applies a filament voltage to the filament F, and a grid voltage generation circuit 25 that applies a grid voltage to the grid electrode 3. Yes. The power supply control unit 22 includes a tube voltage control circuit 26 that controls the high voltage circuit 23, a filament voltage control circuit 27 that controls the filament voltage generation circuit 24, and a tube current control circuit 28 that controls the grid voltage generation circuit 25. . The control unit 30 is measured by the control unit 31 that transmits the voltage values to be applied by the voltage generation circuits 23 to 25 of the high-voltage power supply unit 20 to the control circuits 26 to 28 and the measurement circuits 42 and 43. An A-D conversion unit 32 that A / D-converts the current value and transmits it to the control unit 31 is provided.

In the X-ray generator 1 configured as described above, different types of filaments (here, LaB ₆ filaments, filaments whose electron emitting members are made of tantalum (hereinafter referred to as “Ta filaments”), depending on the purpose, W filament) can be attached to the electron gun 2. The Ta filament is configured by winding a wire-shaped electron emitting member made of tantalum around a core-shaped power feeding member made of tungsten.

FIG. 2 is a graph showing the emission characteristics of the filament attached to the electron gun of the X-ray generator shown in FIG. As shown in FIG. 2, when the filament voltage is L1, when the filament F is a LaB ₆ filament, electrons are emitted from the filament F, and when the filament F is a Ta filament and a W filament, the filament F Does not emit electrons. That is, assuming that the filament voltage is L1, only when the filament F is a LaB ₆ filament, the electron beam E is emitted from the filament F, and the aperture current flows due to the incidence of the electron beam E on the aperture portion 8, and this aperture current Is detected via the aperture current measurement circuit 42. When the filament voltage is L2 (L1> L2), electrons are emitted from the filament F when the filament F is a LaB ₆ filament and a Ta filament, and from the filament F when the filament F is a W filament. Electrons are not emitted. That is, assuming that the filament voltage is L2, only when the filament F is a Ta filament, the electron beam E is emitted from the filament F, and the aperture current flows due to the incidence of the electron beam E on the aperture portion 8. It is detected via the aperture current measurement circuit 42. In the present embodiment, the filament F is determined using these characteristics.

  Next, the filament determination method implemented in the X-ray generator 1 is demonstrated, referring FIG. FIG. 3 is a flowchart showing the procedure of the filament determination method performed in the X-ray generator shown in FIG.

First, whether the type of the filament F is a LaB ₆ filament, a Ta filament, or a W filament is set (step S11). In order to warm up, that is, to use the X-ray generator 1, the filament F and the target 5 are used. Are increased to a tube voltage to be applied (hereinafter referred to as “tube voltage during normal operation”) and evacuation in the X-ray tube 10 is started (step S12). In the middle of boosting to the tube voltage during normal operation (for example, 100 kV), a lower tube voltage (for example, 40 kV) and tube current (for example, 30 μA) than during normal operation are set. A filament voltage L1 (for example, 1V) is set (step S13).

Then, it is determined whether or not an aperture current is detected in a state where the filament voltage L1 is applied to the filament F (step S14). If an aperture current (for example, 10 μA) is detected, the setting is made in step S11. It is determined whether or not the type of the filament F is a LaB ₆ filament (step S15). As a result, if the set type of filament F is not LaB ₆ filament, warm-up is stopped (step S16), and it is determined that the type of filament F actually attached is LaB ₆ filament. This is notified (step S17). On the other hand, when the type of filament F set is LaB ₆ filament, warm-up is continued (step S18), and when the warm-up is completed (step S19), X-rays are generated with the tube voltage during normal operation. The device 1 is operated.

  Further, if the aperture current is not detected as a result of the determination in step S14, a filament voltage L2 (for example, 2V) is set as the filament determination voltage (step S21). Then, it is determined whether or not the aperture current is detected in a state where the filament voltage L2 is applied to the filament F (step S22). If the aperture current (for example, 10 μA) is detected, the setting is made in step S11. It is determined whether or not the type of the filament F is Ta filament (step S23). As a result, when the set type of the filament F is not a Ta filament, the warm-up is stopped (step S24), and it is determined that the type of the actually installed filament F is a Ta filament. A message to that effect is notified (step S25). On the other hand, when the set type of the filament F is a Ta filament, the warm-up is continued (step S18), and when the warm-up is completed (step S19), the X-ray generator is used with the tube voltage during normal operation. 1 is activated.

  Further, if the aperture current is not detected as a result of the determination in step S22, it is determined whether or not the type of filament F set in step S11 is a W filament (step S26). As a result, when the set type of the filament F is not the W filament, the warm-up is stopped (step S27), and it is determined that the type of the actually installed filament F is the W filament. A message to that effect is notified (step S28). On the other hand, when the set type of filament F is a W filament, warm-up is continued (step S18), and when warm-up is completed (step S19), the X-ray generator uses the tube voltage during normal operation. 1 is activated.

As described above, in the X-ray generation apparatus 1, first, when the filament F is a LaB ₆ filament, electrons are emitted, and when the filament F is a Ta filament, electrons are not emitted. It is determined whether the filament F is a LaB ₆ filament or a Ta filament. Next, whether the filament F is a Ta filament or a W filament under the condition that electrons are emitted when the filament F is a Ta filament and no electrons are emitted when the filament F is a W filament. Is determined. As described above, since the type of the filament F can be determined under a condition closer to that during normal operation of the X-ray generator 1, erroneous determination can be prevented and the type of the filament F attached to the electron gun 2 can be determined. It becomes possible to determine accurately.

  Further, in the X-ray generator 1, the type of the filament F is determined in the middle of increasing the tube voltage during normal operation. Therefore, since the filament F can be determined before reaching the tube voltage (100 kV in the present embodiment) in the actual operation (normal operation) state (40 kV in the present embodiment), it is quick and efficient. The filament can be well determined. Therefore, even when the filament F is wrong, the normal operation can be performed without taking a large time lag from the case where the regular filament F is used from the beginning.

  In the X-ray generator 1, the type of the filament F is determined based on the aperture current flowing in the aperture portion 8 that is a predetermined portion of the electron path 7 through which the electron beam E emitted from the electron gun 2 passes. Is called. Thus, by detecting the electrons actually emitted into the electron passage 7, it is possible to accurately determine the type of the filament F attached to the electron gun 2.

  The present invention is not limited to the embodiment described above.

  For example, in the above embodiment, the type of the filament F is determined by detecting the aperture current flowing in the aperture portion 8 which is a predetermined portion of the electron path 7 through which the electron beam E emitted from the electron gun 2 passes. It is not limited to this. By detecting the tube current flowing from the high-voltage power supply unit 20 to the filament F (that is, by detecting the amount of electrons supplied to the filament F from the high-voltage power supply unit 20 to emit electrons), the type of the filament F is changed. You may judge. Further, the type of the filament F may be determined by detecting the current flowing through the target 5 (that is, by detecting the electrons actually reaching the target 5). Further, the type of the filament F may be determined by detecting, for example, the X-ray detection device 50 with X-rays emitted from the X-ray generator 1 when electrons are emitted from the filament F. Also in these cases, the type of the filament F attached to the electron gun 2 can be accurately determined. Note that the type of the filament F may be determined by detecting a current flowing in a predetermined portion of the electron path 7 other than the aperture portion 8. Moreover, in the said embodiment, although filament voltage L1, L2 (L1 <L2) was used in the order of L1, L2, conversely, it can determine also in the order of L2, L1. In the above embodiment, the transmission X-ray generator is used. However, a reflection X-ray generator that extracts X-rays in a direction different from the incident direction of the electron beam E may be used.

It is a block diagram of one Embodiment of the X-ray generator which concerns on this invention. It is a graph which shows the emission characteristic of the filament attached to the electron gun of the X-ray generator shown by FIG. It is a flowchart which shows the procedure of the filament determination method implemented in the X-ray generator shown by FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... X-ray generator, 2 ... Electron gun, 5 ... Target, 7 ... Electron passage, 20 ... High voltage power supply part, F ... Filament, E ... Electron beam.

Claims (6)

An X-ray generator for causing an electron beam emitted from an electron gun to enter a target and emitting X-rays from the target,
When a filament of the electron gun is a first filament, electrons are emitted, and when the filament is a second filament, a predetermined voltage is applied to the filament under the condition that electrons are not emitted, When a predetermined current flowing when electrons are emitted from the filament is detected, the filament is determined to be the first filament, and when the predetermined current is not detected, the filament is An X-ray generator that determines that the second filament is used.   In the middle of boosting to the tube voltage to be applied between the filament and the target, the predetermined voltage is applied to the filament, and when the predetermined current is detected, the filament is 2. The X-ray generator according to claim 1, wherein it is determined that the filament is a filament, and if the predetermined current is not detected, the filament is determined to be the second filament.   The X-ray generator according to claim 1, wherein the predetermined current is a current that flows in a predetermined portion of an electron path through which the electron beam emitted from the electron gun passes.   The X-ray generator according to claim 1, wherein the predetermined current is a tube current flowing from the power supply unit to the filament.   The X-ray generator according to claim 1, wherein the predetermined current is a current flowing through the target. A filament determination method implemented in an X-ray generator that causes an electron beam emitted from an electron gun to enter a target and emit X-rays from the target,
When a filament of the electron gun is a first filament, electrons are emitted, and when the filament is a second filament, a predetermined voltage is applied to the filament under the condition that electrons are not emitted, When a predetermined current flowing when electrons are emitted from the filament or a predetermined X-ray emitted is detected, it is determined that the filament is the first filament, and the predetermined current and the predetermined current are determined. If the X-ray is not detected, it is determined that the filament is the second filament.

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