Electron gun, x-ray tube, and inspection device

Abstract

To provide an electron gun that can prevent peeling of insulating material on a surface of a filament, an X-ray tube, an inspection device, and a method for manufacturing an electron gun.SOLUTION: An electron gun comprises: a housing that exhibits a cylindrical shape; a first stem pin that is provided inside the housing on a side of a first end; a focusing electrode that is provided inside the housing on a side of a second end opposite to the side of the first end; an indirectly heated cathode that is provided on the focusing electrode; a first end that is provided on a side of the focusing electrode provided with the indirectly heated cathode with an insulating part therebetween; a tab that is electrically connected to the first end and a lead of a heater provided on the indirectly heated cathode; and a first lead wire that is provided inside the housing, electrically connected to the first stem pin on a side of one end, and electrically connected to the first end on a side of the other end.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] Embodiments of the present invention relate to an electron gun, an X-ray tube, and an inspection apparatus.

Background Art

[0002] There is an X-ray tube having a micro focus called a micro focus X-ray tube. An electron gun provided in such an X-ray tube includes a indirectly heated cathode that emits electrons, a focusing electrode that electrostatically focuses the electrons, and a stem pin for electrically connecting the indirectly heated cathode and the focusing electrode to an external control device or the like. In this case, the indirectly heated cathode is provided with a heater having a filament and a sleeve into which the filament of the heater is inserted. Further, in order to electrically insulate between the filament and the sleeve, the surface of the filament is coated with an insulating material such as ceramics.

[0003] Here, in order to electrically connect the heater of the indirectly heated cathode to the stem pin, the stem pin is connected to a tab connected to the lead of the heater. In this case, the stem pin is connected to the tab with the filament of the heater inserted into the sleeve. Therefore, a force may be applied to the filament via the tab. When a force is applied to the filament, sliding may occur between the filament and the sleeve, and the insulating material on the surface of the filament may peel off. Therefore, development of a technique capable of suppressing peeling of the insulating material on the surface of the filament has been desired.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0005] The problem to be solved by the present invention is to provide an electron gun, an X-ray tube, and an inspection apparatus that can suppress peeling of the insulating material on the surface of the filament.

Means for Solving the Problems

[0006] The electron gun according to the embodiment includes a housing having a cylindrical shape, a first stem pin provided on the first end side inside the housing, a focusing electrode provided on the second end side inside the housing, which is opposite to the first end side, a indirectly heated cathode provided on the focusing electrode, a first terminal provided on the side of the focusing electrode where the indirectly heated cathode is provided via an insulating portion, a lead of a heater provided on the indirectly heated cathode, and a tab electrically connected to the first terminal and the lead of the heater; and a first lead wire provided inside the housing, one end side of which is electrically connected to the first stem pin and the other end side of which is electrically connected to the first terminal.

Brief Description of the Drawings

[0007]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Best Mode for Carrying Out the Invention

[0008] Hereinafter, embodiments will be exemplified with reference to the drawings. In each drawing, the same components are denoted by the same reference numerals, and detailed descriptions thereof will be omitted as appropriate.

[0009] (Electron gun) FIG. 1 is a schematic cross-sectional view for exemplifying an electron gun 1 according to the present embodiment. FIG. 2 is a schematic perspective cross-sectional view of the electron gun 1. FIG. 3 is a schematic partial cross-sectional view of the electron gun 1. FIG. 4 is a schematic perspective partial cross-sectional view of the electron gun 1. As shown in FIGS. 1 to 4, the electron gun 1 includes, for example, a housing 2, a focusing electrode 3, a focusing electrode 4, a holder 5, a stem pin 6, an indirectly heated cathode 7, a terminal 8, a tab 9, and a lead wire 10.

[0010] The housing 2 has a cylindrical shape and extends, for example, in one direction. The housing 2 can be, for example, a cylinder with both ends open. A hole 2a can be provided on the side surface of the housing 2. The hole 2a is used, for example, for aligning the indirectly heated cathode 7 housed inside the housing 2 and for joining the lead wire 10.

[0011] The focusing electrode 3 is provided at one opening of the housing 2. The focusing electrode 3 is formed of a conductive material such as metal and has, for example, a main body portion 3a and a flange 3b. The main body portion 3a and the flange 3b can be integrally formed. The main body portion 3a has, for example, a cylindrical shape and has a recess 3a1 that opens at an end opposite to the indirectly heated cathode 7 side. A hole 3a2 penetrating in the thickness direction is provided on the bottom surface of the recess 3a1. The flange 3b has a plate shape and is provided on the side surface of the main body portion 3a. The periphery of the flange 3b is joined to the end of the housing 2.

[0012] The focusing electrode 4 is provided inside the housing 2. The focusing electrode 4 is provided on the flange 3b of the focusing electrode 3 via a spacer 11 formed of an insulating material such as ceramics, for example. The focusing electrode 4 faces the main body portion 3a of the focusing electrode 3. The focusing electrode 4 is formed of a conductive material such as metal and, for example, has a cylindrical shape. The focusing electrode 4 has a recess 4b that opens at an end on the side opposite to the focusing electrode 3 side, and a recess 4a that opens at the bottom surface of the recess 4b. A hole 4a1 penetrating in the thickness direction is provided at the bottom surface of the recess 4a. The hole 3a2 of the focusing electrode 3 and the hole 4a1 of the focusing electrode 4 are provided so as to be substantially coaxial with the central axis of the indirectly heated cathode 7, for example. The focusing electrodes 3 and 4 are provided on one end side (corresponding to an example of the second end side) inside the housing 2.

[0013] Electrons emitted from the indirectly heated cathode 7 pass through the hole 4a1 of the focusing electrode 4 and the hole 3a2 of the focusing electrode 3 and are incident on the targets 23 and 28 described later. At this time, by controlling the voltage applied to the focusing electrode 4, the amount of electrons incident on the targets 23 and 28 can be increased or decreased. Further, the spacer 11 sets the distance between the hole 4a1 of the focusing electrode 4 and the hole 3a2 of the focusing electrode 3 to a predetermined focal diameter at the targets 23 and 28. That is, the focusing electrode 3 and the focusing electrode 4 serve as an electron lens that focuses electrons emitted from the indirectly heated cathode 7. The X-ray tubes 20 and 20a provided with the electron gun 1 having such a configuration can be, for example, microfocus X-ray tubes having a microfocus.

[0014] The holder 5 is provided inside the housing 2, for example. The holder 5 can be provided, for example, near the opening on the side opposite to the focusing electrode 3 side of the housing 2. The holder 5 has a plate shape and is formed of an insulating material such as ceramics, for example.

[0015] The stem pins 6 are rod-shaped and are formed of a conductive material such as metal. A plurality of stem pins 6 can be provided. For example, a pair of stem pins 6a (corresponding to an example of the first stem pin) electrically connected to the indirectly heated cathode 7 and a pair of stem pins 6b (corresponding to an example of the second stem pin) electrically connected to the focusing electrodes 3 and 4 can be provided. The stem pins 6a and 6b are provided on the end side (corresponding to an example of the first end side) inside the housing 2, which is opposite to the side where the focusing electrodes 3 and 4 are provided. For example, the stem pins 6a and 6b can be fixed to the holder 5 by brazing. The stem pins 6a and 6b extend, for example, in a direction along the central axis of the housing 2. One end of the stem pins 6a and 6b is provided inside the housing 2, and the other end of the stem pins 6a and 6b is provided outside the housing 2. A control device provided in the inspection device 100 or the like is electrically connected to the stem pins 6a and 6b.

[0016] The indirectly heated cathode 7 is provided, for example, inside the housing 2. The indirectly heated cathode 7 is provided on the focusing electrode 4 via a holder 12 formed of a material having heat resistance and insulation such as ceramics. In this case, the holder 12 can be provided, for example, inside the concave portion 4b of the focusing electrode 4. In this way, it becomes easy to align the hole 3a2 of the focusing electrode 3, the hole 4a1 of the focusing electrode 4, and the central axis of the indirectly heated cathode 7.

[0017] The indirectly heated cathode 7 has, for example, a sleeve 7a, an emitter 7b, and a heater 7c. The sleeve 7a is cylindrical and is formed of, for example, metal or the like. The emitter 7b is provided at the end of the sleeve 7a on the side of the focusing electrode 4. A layer containing an electron-emitting substance is provided on the surface of the emitter 7b on the side opposite to the focusing electrode 4 side. Note that the emitter 7b may be, for example, a so-called impregnated cathode or the like.

[0018] The heater 7c is provided inside the sleeve 7a. The heater 7c is formed of a conductive material such as metal, for example. The heater 7c has, for example, a filament 7c1 in which a linear material is wound in a spiral shape, and a pair of leads 7c2 connected to the ends of the filament 7c1. The filament 7c1 and the pair of leads 7c2 can be integrally formed. In this case, the filament 7c1 is provided inside the sleeve 7a, and the ends of the pair of leads 7c2 on the side opposite to the filament 7c1 side are provided outside the sleeve 7a. The pair of leads 7c2 extends, for example, in a direction along the central axis of the housing 2.

[0019] Also, in order to electrically insulate between the heater 7c and the sleeve 7a, the surface of the portion of the heater 7c provided inside the sleeve 7a (for example, the filament 7c1) is coated with a material having heat resistance and insulation. For example, the surface of the filament 7c1 is coated with ceramics such as aluminum oxide.

[0020] The terminal 8 has, for example, a rod shape and is formed of a conductive material such as metal. The terminal 8 extends, for example, in a direction along the central axis of the housing 2. A plurality of terminals 8 can be provided. For example, a pair of terminals 8a (corresponding to an example of the first terminal) electrically connected to the heater 7c of the indirectly heated cathode 7 via a tab 9, and a pair of terminals 8b (corresponding to an example of the second terminal) electrically connected to the focusing electrodes 3 and 4 can be provided. The pair of terminals 8a can be provided, for example, at the end of the focusing electrode 4 on the side where the indirectly heated cathode 7 is provided via an insulating portion 13 formed of an insulating material such as ceramics. The pair of terminals 8b can be provided, for example, at the end of the focusing electrode 4 on the side where the indirectly heated cathode 7 is provided.

[0021] The tab 9 has, for example, a thin plate shape and is formed of a conductive material such as metal. A pair of tabs 9 can be provided. Each of the pair of tabs 9 is electrically connected to the lead 7c2 of the heater 7c provided on the indirectly heated cathode 7 and the terminal 8a.

[0022] The lead wire 10 is linear and formed of a conductive material such as metal. For example, the lead wire 10 can be a nickel wire with a wire diameter of about 0.5 mm. A plurality of lead wires 10 can be provided. The plurality of lead wires 10 are provided inside the housing 2. For example, one end side of the lead wire 10a (corresponding to an example of the first lead wire) is electrically connected to the stem pin 6a, and the other end side of the lead wire 10a is electrically connected to the terminal 8a. For example, one end side of the lead wire 10b (corresponding to an example of the second lead wire) is electrically connected to the stem pin 6b, and the other end side of the lead wire 10b is electrically connected to the terminal 8b.

[0023] Here, the functions and effects of the terminal 8 and the lead wire 10 will be further described. FIG. 5 is a schematic cross-sectional view for illustrating an electron gun 300 according to a comparative example. As shown in FIG. 5, the electron gun 300 includes a housing 2, a focusing electrode 3, a focusing electrode 4, a holder 5, a stem pin 306, an indirectly heated cathode 7, and a tab 309.

[0024] The stem pin 306 is rod-shaped and a plurality of them are provided. For example, a pair of stem pins 306a electrically connected to the indirectly heated cathode 7 and a pair of stem pins 306b electrically connected to the focusing electrode 3 and the focusing electrode 4 are provided. The tab 309 is in the shape of a thin plate and a pair of them are provided. Each of the pair of tabs 309 electrically connects the stem pin 306a and the heater 7c of the indirectly heated cathode 7. The stem pin 306b and the lead 7c2 of the heater 7c are electrically connected to each of the pair of tabs 309. That is, in the electron gun 300 according to the comparative example, the aforementioned terminal 8a and the lead wire 10a are not provided, and the stem pin 306a is directly connected to the tab 309.

[0025] When electrically connecting the stem pin 306a to the tab 309, the electrical connection is made with the filament 7c1 of the heater 7c inserted into the sleeve 7a. Also, the electrical connection is made in the narrow space inside the housing 2. Therefore, when making the electrical connection, a force is likely to be applied to the filament 7c1 via the tab 309. When a force is applied to the filament 7c1, sliding may occur between the filament 7c1 and the sleeve 7a, and the insulating material on the surface of the filament 7c1 may peel off. When the insulating material on the surface of the filament 7c1 peels off, a short circuit may occur between the heater 7c and the sleeve 7a, leading to a decrease in the function of the electron gun 300 or a malfunction of the electron gun 300.

[0026] On the other hand, since the electron gun 1 according to the present embodiment is provided with the terminals 8a, outside the housing 2, a module 1a having the focusing electrodes 3, 4, the indirectly heated cathode 7, the terminals 8a, the tab 9, the spacer 11, the holder 12, and the insulating portion 13 can be manufactured. Then, the manufactured module 1a can be inserted into the housing 2 from one end side of the housing 2 and fixed to one end of the housing 2. For example, the flange 3b of the focusing electrode 3 can be welded or brazed to the end of the housing 2.

[0027] FIG. 6 is a schematic exploded cross-sectional view for illustrating the manufacturing procedure of the module 1a. First, a module 1a including the focusing electrodes 3, 4, the indirectly heated cathode 7, a pair of terminals 8a, and a tab blank 9a is manufactured.

[0028] For example, as shown in FIG. 6, a pair of leads 7c2 of the heater 7c are electrically connected to the tab blank 9a. For example, a pair of leads 7c2 of the heater 7c can be welded or brazed to the tab blank 9a. Also, the sleeve 7a provided with the emitter 7b is fixed inside the hole of the holder 12. The fixing of the sleeve 7a can be performed, for example, by brazing. Further, the focusing electrode 3, the spacer 11, the focusing electrode 4, and the insulating portion 13 are laminated, and the terminal 8a is fixed to the insulating portion 13. These can be fixed, for example, by brazing.

[0029] Next, the filament 7c1 of the heater 7c is inserted inside the sleeve 7a. Next, with the filament 7c1 inserted into the sleeve 7a, the holder 12 is fixed inside the concave portion 4b of the focusing electrode 4. The fixing can be performed, for example, by brazing. Next, the pair of terminals 8a are electrically connected to the tab blank 9a. For example, the pair of terminals 8a can be welded or brazed to the tab blank 9a. That is, in the process of manufacturing the module 1a, the pair of leads 7c2 of the heater 7c provided on the indirectly heated cathode 7 and the pair of terminals 8a are electrically connected to the tab blank 9a.

[0030] Next, the region of the tab blank 9a where one lead 7c2 and one terminal 8a are electrically connected and the region of the tab blank 9a where the other lead 7c2 and the other terminal 8a are electrically connected are separated. By dividing the tab blank 9a, a pair of tabs 9 are formed. In the above manner, the module 1a having the focusing electrode 3, the focusing electrode 4, the indirectly heated cathode 7, the terminal 8, the tab 9, the spacer 11, the holder 12, and the insulating portion 13 can be manufactured.

[0031] Here, as described above, the pair of leads 7c2 of the heater 7c are electrically connected to the tab blank 9a before the filament 7c1 is inserted into the sleeve 7a. Therefore, when the pair of leads 7c2 are electrically connected to the tab blank 9a, it is possible to suppress the peeling of the insulating material on the surface of the filament 7c1.

[0032] Also, a pair of terminals 8a are electrically connected to the tab blank 9a before the tab blank 9a is divided into tabs 9. That is, the pair of terminals 8a are electrically connected to the tab blank 9a which is more rigid than the tab 9. Therefore, when connecting, it becomes difficult for a force to be applied to the filament 7c1 via the tab blank 9a. As a result, it is possible to suppress the peeling of the insulating material on the surface of the filament 7c1.

[0033] In addition, since the electrical connection between the lead 7c2, the terminal 8a, and the tab blank 9a can be performed outside the housing 2, workability can be improved. Also, if necessary, a welding jig or a brazing jig can be used to fix the connection portion. Therefore, it becomes even easier to suppress a force from being applied to the filament 7c1 during connection. As described above, since the electron gun 1 according to the present embodiment is provided with the terminal 8a, it is possible to suppress the peeling of the insulating material on the surface of the filament 7c1.

[0034] (X-ray tube, and inspection apparatus) Next, an example of the X-ray tube 20 will be given. FIG. 7 is a schematic cross-sectional view for exemplifying the X-ray tube 20 according to the present embodiment. As shown in FIG. 7, the X-ray tube 20 includes, for example, an electron gun 1, an envelope 21, a holder 22, and a target 23.

[0035] The envelope 21 has, for example, an insulating portion 21a and a lid 21b. The insulating portion 21a has a cylindrical shape and both ends are open. The insulating portion 21a can be formed of an insulating material such as glass or ceramics, for example. The lid 21b is provided at one end of the insulating portion 21a. A hole 21b1 is provided in the lid 21b. The lid 21b can be formed of, for example, metal. In this case, a high voltage is applied to the lid 21b (target 23) and the stem pin 6 of the electron gun 1. For example, the lid 21b (target 23) can be used as the anode and the indirectly heated cathode 7 of the electron gun 1 can be used as the cathode.

[0036] The holder 22 has, for example, a cylindrical portion 22a and a flange 22b. The cylindrical portion 22a has a bottomed cylindrical shape. A hole 22a1 is provided in the bottom surface of the cylindrical portion 22a. The electron gun 1 is provided inside the cylindrical portion 22a. Further, the housing 2 of the electron gun 1 is joined to the inner wall of the cylindrical portion 22a so as to be airtight. The flange 22b has a plate shape and is provided on the side surface of the cylindrical portion 22a. The flange 22b is joined to the end of the insulating portion 21a on the side opposite to the side where the lid 21b is provided so as to be airtight.

[0037] The target 23 has a plate shape and is provided on the lid 21b. The target 23 closes the hole 21b1 of the lid 21b. The target 23 is joined to the lid 21b so as to be airtight. The target 23 has, for example, a plate material and a film provided on the surface of the plate material. The plate material contains a material capable of transmitting X-rays. The material of the plate material is, for example, beryllium or the like. The thickness of the plate material is, for example, about 1 mm. The film provided on the surface of the plate material contains a material that generates X-rays when thermoelectrons collide. The material of the film is, for example, at least any one of Rh (rhodium), W (tungsten), molybdenum (Mo), and chromium (Cr). The thickness of the film is, for example, about 1 μm. The target 23 is a so-called transmission type target.

[0038] Also, for example, the center of the hole 22a1 of the cylindrical portion 22a and the center of the hole 21b1 of the lid 21b can be made to overlap the central axis of the electron gun 1. The internal space of the outer container 21 is in an atmosphere (also referred to as a vacuum state) depressurized from the atmospheric pressure.

[0039] When a voltage is applied to the indirectly heated cathode 7 (heater 7c) of the electron gun 1, the emitter 7b is heated and thermoelectrons 24 are generated. The generated thermoelectrons 24 are incident on the target 23. When the thermoelectrons 24 are incident on the target 23, X-rays 25 are generated, and the generated X-rays 25 pass through the target 23 and are irradiated outside the X-ray tube 20.

[0040] As shown in FIG. 7, the X-ray tube 20 can be provided in the inspection apparatus 100. For example, the X-ray tube 20 can be held by a holder 101 provided in the inspection apparatus 100. As described above, the X-ray tube 20 including the electron gun 1 can be a microfocus X-ray tube having a micro focus. Therefore, the X-ray tube 20 can be suitably used, for example, in an inspection apparatus that magnifies a sample at a high resolution and performs a non-destructive inspection. For example, the inspection apparatus 100 can be an X-ray transmission inspection apparatus, an X-ray CT scan apparatus, or the like. However, the use of the X-ray tube 20 is not limited to the examples shown.

[0041] FIG. 8 is a schematic cross-sectional view for illustrating an X-ray tube 20a according to another embodiment. As shown in FIG. 8, the X-ray tube 20a includes, for example, an electron gun 1, an outer enclosure 26, a holder 22, a target holder 27, and a target 28. The outer enclosure 26 has, for example, an insulating portion 26a and a lid 26b. The insulating portion 26a can be the same as the insulating portion 21a described above, for example. The lid 26b can be the same as the lid 21b described above, for example.

[0042] The target holder 27 has a columnar shape and is joined to the lid 26b in an airtight manner. The target holder 27 extends in a direction along the central axis of the outer enclosure 26. One end of the target holder 27 is provided inside the outer enclosure 26 and faces the indirectly heated cathode 7 of the electron gun 1 at a predetermined distance. One end of the target holder 27 is inclined with respect to the central axis of the electron gun 1. The other end of the target holder 27 is exposed outside the outer enclosure 26. The target holder 27 can be formed of a conductive material such as metal. In this case, a high voltage is applied to the target holder 27 and the stem pin 6 of the electron gun 1. For example, the target holder 27 can be used as an anode and the indirectly heated cathode 7 of the electron gun 1 can be used as a cathode.

[0043] The target 28 is plate-shaped and is provided inside the outer enclosure 26. The target 28 is provided at an end of the target holder 27 that is inclined with respect to the central axis of the electron gun 1. Therefore, the target 28 is inclined with respect to the central axis of the electron gun 1. The target 28 contains a material that generates X-rays when the thermoelectrons 24 collide with it. The material of the target 28 is, for example, at least any one of Rh (rhodium), W (tungsten), molybdenum (Mo), and chromium (Cr). The target 28 is a so-called reflection-type target.

[0044] When a voltage is applied to the indirectly heated cathode 7 (heater 7c) of the electron gun 1, the emitter 7b is heated and thermoelectrons 24 are generated. The generated thermoelectrons 24 are incident on the target 28. When the thermoelectrons 24 are incident on the target 28, X-rays 25 are generated, and the generated X-rays 25 are irradiated in a direction intersecting the central axis of the outer enclosure 26. The irradiated X-rays 25 pass through the insulating portion 26a of the outer enclosure 26 and are irradiated outside the X-ray tube 20a.

[0045] Similar to the X-ray tube 20 described above, the X-ray tube 20a can be provided in the inspection device 100. For example, the X-ray tube 20a can be held by a holder 101 provided in the inspection device 100. The X-ray tube 20a equipped with the electron gun 1 can also be a microfocus X-ray tube having a micro focus. Therefore, the X-ray tube 20a can also be used in an X-ray transmission inspection device, an X-ray CT scan device, etc. However, the use of the X-ray tube 20a is not limited to the examples shown.

[0046] (Method for manufacturing an electron gun) Next, an example of the method for manufacturing the electron gun 1 according to the present embodiment will be given. The method for manufacturing the electron gun 1 according to the present embodiment can include, for example, the following steps. A step of manufacturing a module 1a having a focusing electrode 3, a focusing electrode 4, an indirectly heated cathode 7, a terminal 8, a tab 9, a spacer 11, a holder 12, and an insulating portion 13. A step of providing the module 1a and a plurality of stem pins 6 fixed to the holder 5 inside the housing 2. A step of electrically connecting one end side of the lead wire 10 to the tab 9 and electrically connecting the other end side of the lead wire 10 to the stem pin 6.

[0047] The step of manufacturing the module 1a can be the same as that illustrated in FIG. 6, and thus detailed description thereof is omitted. Also, since the step of providing the module 1a and the plurality of stem pins 6 fixed to the holder 5 can apply known techniques, detailed description thereof is omitted.

[0048] Therefore, hereinafter, the electrical connection between the lead wire 10, the terminal 8, and the stem pin 6 will be described. The lead wire 10a can be welded or brazed to the terminal 8a and the stem pin 6a. The lead wire 10b can be welded or brazed to the terminal 8b and the stem pin 6b. In this case, welding can be performed, for example, by laser welding or resistance welding.

[0049] As described above, in the manufacturing process of the module 1a, the terminal 8a and the tab 9 are electrically connected. Therefore, one end of the lead wire 10a can be electrically connected to the terminal 8a. Therefore, it becomes difficult for a force to be applied to the filament 7c1, and thus peeling of the insulating material on the surface of the filament 7c1 can be suppressed.

[0050] Also, when electrically connecting the lead wire 10a, it is preferable to connect one end of the lead wire 10a to the terminal 8a and then connect the other end of the lead wire 10a to the stem pin 6a. By doing so, handling and deformation of the lead wire 10a become easy, and thus it becomes more difficult for a force to be applied to the filament 7c1. Therefore, peeling of the insulating material on the surface of the filament 7c1 can be further suppressed.

[0051] Note that since the electrical connection between the lead wire 10b and the terminal 8b and the stem pin 6b has no direct influence on the application of force to the filament 7c1, the connection procedure can be set arbitrarily.

[0052] As mentioned above, some embodiments of the present invention have been illustrated. However, these embodiments are presented as examples and are not intended to limit the scope of the invention. Regarding the above-described embodiments, those in which those skilled in the art appropriately add, delete, or modify components, or add, omit, or change conditions of processes, are also included in the scope of the present invention as long as they have the features of the present invention. In addition, each element included in each of the above-described embodiments can be combined as much as possible, and those obtained by combining them are also included in the scope of the present invention as long as they include the features of the present invention.

[0053] Hereinafter, appendices regarding the above-described embodiments are shown.

[0054] (Appendix 1) A housing having a cylindrical shape, A first stem pin provided on the first end side inside the housing, A focusing electrode provided on the second end side inside the housing, which is opposite to the first end side, A indirectly heated cathode provided on the focusing electrode, A first terminal provided on the side of the focusing electrode where the indirectly heated cathode is provided, via an insulating portion, A tab electrically connected to the lead of the heater provided on the indirectly heated cathode and the first terminal, A first lead wire provided inside the housing, one end side of which is electrically connected to the first stem pin and the other end side of which is electrically connected to the first terminal, An electron gun comprising the above.

[0055] (Appendix 2) A second terminal provided on the side of the focusing electrode where the indirectly heated cathode is provided, A second stem pin provided on the first end side inside the housing, a second lead wire provided inside the housing, further comprising, One end side of the second lead wire is electrically connected to the second stem pin, and the other end side of the second lead wire is electrically connected to the second terminal. The electron gun according to Supplementary Note 1.

[0056] (Supplementary Note 3) The indirectly heated cathode has a cylindrical shape and has a sleeve in which the filament of the heater is provided. The surface of the filament is coated with a material having insulating properties. The electron gun according to Supplementary Note 1 or 2.

[0057] (Supplementary Note 4) an outer enclosure, an electron gun according to any one of Supplementary Notes 1 to 3 provided inside the outer enclosure, a target that generates X-rays when thermoelectrons from the electron gun are incident, An X-ray tube comprising.

[0058] (Supplementary Note 5) An inspection apparatus comprising the X-ray tube according to Supplementary Note 4.

Explanation of Reference Numerals

[0059] 1 Electron gun, 1a Module, 2 Housing, 3 Focusing electrode, 4 Focusing electrode, 6 Stem pin, 6a Stem pin, 6b Stem pin, 7 Indirectly heated cathode, 7a Sleeve, 7c Heater, 7c1 Filament, 7c2 Lead, 8 Terminal, 8a Terminal, 8b Terminal, 9 Tab, 9a Tab blank, 10 Lead wire, 10a Lead wire, 10b Lead wire, 20 X-ray tube, 20a X-ray tube, 21 Outer enclosure, 23 Target, 26 Outer enclosure, 27 Target holder, 28 Target

Claims

1. A housing having a cylindrical shape, A first stem pin provided on the first end side inside the housing, A focusing electrode provided on the second end side inside the housing, which is opposite to the first end side, A directly heated cathode provided on the focusing electrode, A first terminal provided on the side of the focusing electrode where the directly heated cathode is provided, via an insulating portion, A tab electrically connected to the lead of the heater provided on the directly heated cathode and the first terminal, A first lead wire provided inside the housing, with one end side electrically connected to the first stem pin and the other end side electrically connected to the first terminal, An electron gun comprising the above.

2. A second terminal provided on the side of the focusing electrode where the directly heated cathode is provided, A second stem pin provided on the first end side inside the housing, A second lead wire provided inside the housing, Further comprising, One end side of the second lead wire is electrically connected to the second stem pin, and the other end side of the second lead wire is electrically connected to the second terminal. The electron gun according to Claim 1.

3. The directly heated cathode has a cylindrical shape and has a sleeve on which the filament of the heater is provided, The surface of the filament is coated with an insulating material. The electron gun according to Claim 1 or 2.

4. An outer enclosure, The electron gun according to Claim 1 or 2 provided inside the outer enclosure, A target that generates X-rays when thermoelectrons from the electron gun are incident, An X-ray tube comprising the above.

5. An inspection device comprising the X-ray tube according to Claim 4.

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