Vacuum tube, x-ray tube and x-ray inspection apparatus

Abstract

To provide a vacuum tube that can reduce a cost by curbing the number of components, an X-ray tube, and an X-ray inspection apparatus having the same.SOLUTION: An X-ray tube 10, which is composed of a vacuum tube emitting an electron from a filament 22 provided within a vacuum region Av, includes a ceramic filament support part 21 that constitutes a part of a vacuum container 11 forming the vacuum region Av, and a Wehnelt electrode 32 and a filament electrode 31 that is a conductive rod supported by the filament support part 21 and passing through the vacuum region Av and the outside. The filament 22 is energized by being connected to the filament electrode 31. The Wehnelt electrode 32 of the filament electrode 31 and the Wehnelt electrode 32 has a screw structure comprising a screw hole 33.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to a vacuum tube, an X-ray tube, and an X-ray inspection device. [Background technology]

[0002] As a vacuum tube in which the inside of the container is kept in a vacuum state, Patent Document 1 discloses an electron gun equipped with a Wehnelt having a hole for narrowing down the electrons emitted from a filament.

[0003] Furthermore, Patent Document 2 discloses an X-ray tube having a vacuum vessel consisting of a vacuum enclosure having a metallic cylindrical wall portion capped at one end with a ceramic collar and at the other end with an anode assembly. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 49-17166 (Fig. 2) [Patent Document 2] Special Publication No. 2015-525953 Summary of the Invention [Problem to be solved by the invention]

[0005] In the electron gun described in Patent Document 1, the Wehnelt is fixed to a support plate by screws via an insulating plate through which the electrode of the filament penetrates, resulting in a large number of parts and increased costs.

[0006] In particular, metal-ceramic vacuum tubes such as the X-ray tube described in Patent Document 2 can be formed with high precision, but the raw materials and manufacturing equipment are expensive, so it is necessary to reduce the number of parts and keep costs down.

[0007] Therefore, an object of the present invention is to provide a vacuum tube, an X-ray tube, and an X-ray inspection apparatus equipped with the same, which can reduce the number of parts and thereby reduce costs. [Means for solving the problem]

[0008] The present invention comprises the following configurations. (1) A vacuum tube that emits electrons from a filament located within a vacuum region, a non-conductive member that constitutes a part of a vacuum vessel that forms the vacuum region; At least three conductive rods supported by the non-conductive member and extending between the vacuum region and the outside; Equipped with the filament is connected to the conductive rod and energized; At least one of the plurality of conductive rods has a screw structure. Vacuum tube. (2) In the vacuum tube described in (1) above, a target that is irradiated with electrons emitted from the filament; a window portion through which X-rays emitted when the target is irradiated with electrons pass; Equipped with X-ray tube. (3) the X-ray tube (3) that irradiates the transported inspection object (W) with X-rays; an X-ray detector (82) for detecting X-rays transmitted through the object to be inspected; a signal processing unit (83) that inspects the object to be inspected based on image information obtained by the X-ray detector; X-ray inspection equipment. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide a vacuum tube, an X-ray tube, and an X-ray inspection apparatus equipped with the same, which can reduce the number of parts and thereby reduce costs. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a vertical cross-sectional view along the axial direction of an X-ray tube, which is an example of a vacuum tube according to an embodiment. [Figure 2]FIG. 2 is a horizontal cross-sectional view along the axial direction of an X-ray tube, which is an example of a vacuum tube according to an embodiment. [Figure 3] FIG. 3 is a perspective view of the X-ray tube with a part cut away. [Figure 4] FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. [Figure 5] FIG. 5 is a cross-sectional view taken along line VV in FIG. [Figure 6] FIG. 6 is a side view of the cathode structure of the X-ray tube. [Figure 7] FIG. 7 is a schematic diagram of an X-ray inspection device equipped with an X-ray tube. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Fig. 1 is a vertical cross-sectional view along the axial direction of an X-ray tube 10, which is an example of a vacuum tube according to an embodiment. Fig. 2 is a horizontal cross-sectional view along the axial direction of an X-ray tube 10, which is an example of a vacuum tube according to an embodiment. Fig. 3 is a perspective view with a part of the X-ray tube 10 broken away. Fig. 4 is a cross-sectional view taken along line IV-IV in Fig. 1. Fig. 5 is a cross-sectional view taken along line VV in Fig. 1. Fig. 6 is a side view of a cathode structure 12 of the X-ray tube 10.

[0012] 1 to 6, the vacuum tube according to this embodiment is an X-ray tube 10 having a vacuum vessel 11, a cathode structure 12, and an anode structure 13. In this example, an X-ray tube 10 that generates X-rays will be described as an example of the vacuum tube.

[0013] The vacuum vessel 11 is made of a metal material such as stainless steel, etc. The vacuum vessel 11 is formed in a cylindrical shape and has annular flange portions 14 and 15 that protrude inward at one end 11a and the other end 11b.

[0014] The cathode structure 12 is housed in a vacuum vessel 11. The cathode structure 12 is fixed to one end 11a of the vacuum vessel 11. The anode structure 13 is fixed to the other end 11b of the vacuum vessel 11. In the X-ray tube 10, the inside of the vacuum vessel 11, to which the cathode structure 12 and the anode structure 13 are fixed at both ends, is a vacuum region Av, and this vacuum region Av is evacuated.

[0015] The cathode structure 12 has a filament support (non-conductive member) 21, a filament 22, and a Wehnelt 23.

[0016] The filament support 21 is made of a non-conductive material such as ceramic, and is formed in a generally cylindrical shape with a bottom 25. The filament support 21 is housed within the vacuum vessel 11 with the bottom 25 facing the other end 11b of the vacuum vessel 11. The end of the filament support 21 opposite the bottom 25 is airtightly joined and supported by a flange 14 formed at one end 11a of the vacuum vessel 11 via a cylindrical support member 26 and an annular connecting member 27.

[0017] A pair of filament electrodes (conductive rods) 31 and a pair of Wehnelt electrodes (conductive rods) 32 are provided on the bottom 25 of the filament support part 21. These filament electrodes 31 and Wehnelt electrodes 32 are provided on the bottom 25 of the filament support part 21 so as to penetrate between the vacuum region Av and the outside, respectively.

[0018] The filament electrode 31 is made of a conductive metal material and has a fixed portion 35 and an electrode rod portion 36. The filament electrodes 31 are fixed at intervals so that the fixed portions 35 penetrate the bottom portion 25 of the filament support portion 21, and the electrode rod portions 36 protrude from the tip side of the filament support portion 21. Ends of filaments 22 made of wire material such as tungsten are connected to the tips of the electrode rod portions 36 of these filament electrodes 31, respectively. As a result, the filaments 22 are attached so as to span the tips of the electrode rod portions 36 of the filament electrodes 31.

[0019] The Wehnelt electrode 32 is made of a conductive metal material and has a fixed portion 41 and a support rod portion 42. The Wehnelt electrodes 32 are fixed at a distance from each other so that the fixed portion 41 penetrates the bottom portion 25 of the filament support portion 21, and the support rod portion 42 protrudes toward the tip side of the filament support portion 21. The Wehnelt electrode 32 has a screw hole (screw structure) 33 in its support rod portion 42.

[0020] The Wehnelt 23 is made of a conductive metal material. The Wehnelt 23 is formed in a cylindrical shape, and a mounting wall 51 that protrudes toward the inner periphery is formed in the axial middle of the Wehnelt 23. The mounting wall 51 has a pair of holes 52 and a pair of screw holes 53. The pair of holes 52 and the pair of screw holes 53 are located on opposite sides of the center. The screw holes 53 are located at different positions in the circumferential direction relative to the holes 52.

[0021] Flat head screws 54 are inserted into the holes 52 of the mounting wall 51, and these flat head screws 54 are screwed into the threaded holes 33 formed in the support rod 42 of the Wehnelt electrode 32. As a result, the Wehnelt electrode 23 is screwed to the Wehnelt electrode 32 and supported on the bottom 25 of the filament support part 21.

[0022] The Wehnelt 23 has a disk-shaped wall 55. The wall 55 is made of a conductive metal material. The wall 55 is attached to the mounting wall 51 of the Wehnelt 23 from the tip side of the Wehnelt 23. A slit 56 is formed in the wall 55. The filament 22 fixed to the electrode rod portion 36 of the filament electrode 31 is housed in the slit 56 of the wall 55. The filament 22 is arranged with a substantially uniform gap between the inner circumferential surface of the slit 56 and the outer circumferential side.

[0023] The wall 55 has a pair of holes 57. These holes 57 are arranged on both sides of the slit 56. Screws 58 are inserted into the holes 57 and screwed into the screw holes 53 formed in the mounting wall 51. In this way, the wall 55 is fixed to the mounting wall 51 by the screws.

[0024] The holes 57 formed in the wall body 55 have an inner diameter larger than the outer diameter of the screws 58 inserted into these holes 57. This allows the wall body 55 to be displaced relative to the mounting wall body 51 by the amount of the gap between the outer periphery of the screws 58 and the inner periphery of the screw holes 53 when the screws 58 are loosely screwed into the screw holes 53 of the mounting wall body 51 and temporarily fixed. Therefore, by adjusting the position of the wall body 55 relative to the mounting wall body 51 and mounting it, the wall body 55 can be positioned with a substantially uniform gap between the inner periphery of the slit 56 of the wall body 55 and the outer periphery of the filament 22.

[0025] The cathode structure 12 also has a molecular adsorption member 59. When a current is passed through the molecular adsorption member 59 and it is heated, it adsorbs the surrounding gas and increases the degree of vacuum in the vacuum region Av. The molecular adsorption member 59 has a pair of terminals 59a. One terminal 59a of the molecular adsorption member 59 is connected to the electrode rod portion 36 of one filament electrode 31, and the other terminal 59a is connected to the support rod portion 42 of one Wehnelt electrode 32.

[0026] The anode structure 13 includes an anode fixing member 61 , a target mounting member 62 , and a target 63 .

[0027] The anode fixing member 61 is formed of, for example, a metal material such as stainless steel, which is the same material as the vacuum vessel 11. The anode fixing member 61 has a flange portion 65, which is airtightly joined to a flange portion 15 formed on the other end 11b of the vacuum vessel 11.

[0028] A semi-closed space 66 is formed in the anode fixing member 61. The anode fixing member 61 also has a partition wall 67 on the side facing the vacuum region Av. The partition wall 67 has a communication hole 68 in its center that communicates with the semi-closed space 66. This allows the semi-closed space 66 to communicate with the vacuum region Av in the vacuum vessel 11 via the communication hole 68. The partition wall 67 has a smooth surface 67a on the side facing the vacuum region Av.

[0029] The semi-closed space 66 is composed of an axial space 66a extending in the axial direction of the X-ray tube 10 and a radial space 66b extending in the radial direction of the X-ray tube 10 so as to be perpendicular to the axial space 66a. The communication hole 68 is formed on one end side of the axial space 66a.

[0030] One end of the radial space 66b is open at the circumferential surface of the anode fixing member 61. The opening of this radial space 66b is a window 72 that is sealed by a transmission plate 71 made of, for example, beryllium. An opening 74 is formed at the other end of the radial space 66b, and a suction pipe 73 is connected to this opening 74.

[0031] The target mounting member 62 is made of a metal material that has electrical conductivity and excellent thermal conductivity, such as copper or a copper alloy. The target mounting member 62 has a mounting portion 75, a fitting portion 76, and a flange portion 77. The mounting portion 75 has an inclined end surface, and a plate-shaped target 63 is attached to this end surface. The target 63 is made of tungsten.

[0032] The target mounting member 62 has a fitting portion 76 that fits into a fitting hole 69 formed at the other end of the axial space 66a of the anode fixing member 61, and a flange portion 77 that is joined to the anode fixing member 61. In this way, the target mounting member 62 is fixed to the anode fixing member 61. With the target mounting member 62 fixed to the anode fixing member 61, the target 63 attached to the mounting portion 75 is placed at the end of the axial space 66a in the semi-closed space 66. The target 63 is placed in a state inclined at approximately 45 degrees toward the window portion 72 with respect to the axial direction of the X-ray tube 10.

[0033] In the X-ray tube 10, when evacuating the vacuum region Av, suction is performed through the suction pipe 73 connected to the anode fixing member 61 and communicating with the semi-closed space 66. Thereafter, power is supplied to the molecular adsorption member 59 through the filament electrode 31 and the Wehnelt electrode 32 to which the terminal 59a of the molecular adsorption member 59 is connected. This causes the molecular adsorption member 59 to adsorb the surrounding gas, thereby increasing the degree of vacuum in the vacuum region Av.

[0034] In the X-ray tube 10 configured in this manner, a voltage is applied to the filament 22 so that it serves as the cathode and the target 63 serves as the anode, and current is passed through the filament 22 via the filament electrode 31. Electrons are then emitted from the heated filament 22, narrowed and focused by the Wehnelt 23, and accelerated to collide with the target 63, which serves as the anode. X-rays are thus generated in the target 63, and these X-rays are irradiated to the outside through the window 72.

[0035] As described above, with the X-ray tube 10 according to this embodiment, the Wehnelt 23, which is a component requiring electrical conduction, can be attached to the Wehnelt electrode 32 having the threaded hole 33 in an electrically conductive state by screwing it with the flat head screw 54. This reduces the number of parts required to attach the Wehnelt 23, thereby reducing costs. Moreover, the Wehnelt 23 can be attached in a structure in which only the filament electrode 31 and the Wehnelt electrode 32 are airtightly joined to the filament support part 21 made of a non-conductive material such as ceramic. Therefore, compared to a structure in which the Wehnelt 23 itself is airtightly joined to the filament support part 21, the joining distance can be shortened, and manufacturing costs can be reduced.

[0036] The Wehnelt electrode 23 has a mounting wall 51 that is screwed to the Wehnelt electrode 32 and a wall body 55 that is attached to the mounting wall 51. The wall body 55 has a slit 56 that houses the filament 22 and is attached so as to be displaceable relative to the mounting wall 51. This allows the wall body 55, which has the slit 56 that houses the filament 22, to be attached while being positionally adjusted relative to the mounting wall 51. Therefore, the slit 56, which is important for controlling electrons, can be positioned accurately relative to the filament 22.

[0037] Moreover, since the terminals 59a at both ends of the molecular adsorption member 59 are connected to the Wehnelt electrode 32 having the screw hole 33 and the filament electrode 31 having no screw hole, respectively, power can be supplied from the Wehnelt electrode 32 and the filament electrode 31 to the molecular adsorption member 59 to adsorb the gas in the vacuum region Av, thereby increasing the degree of vacuum in the vacuum region Av.

[0038] Next, an example of an X-ray inspection apparatus equipped with the X-ray tube 10 configured as described above will be described. FIG. 7 is a schematic diagram of an X-ray inspection apparatus 100 equipped with an X-ray tube 10. As shown in FIG. 7, the X-ray inspection apparatus 100 includes an X-ray tube 10, a transport unit 81, an X-ray detector 82, a signal processing unit 83, and a display unit 84, and is incorporated, for example, into a part of a transport line for an inspection object W. The X-ray inspection apparatus 100 includes the X-ray tube 10 having the above-described structure as an X-ray generator.

[0039] The transport unit 81 is a conveyor in which a loop-shaped transport belt 86 is wound around a plurality of transport rollers 85. The transport unit 81 sequentially transports the inspection objects W at intervals in the transport direction A by rotating the transport rollers 85 using a motor 87.

[0040] The X-ray tube 10 is disposed above the transport unit 81, and irradiates the inspection object W, which is transported in the transport direction A by the transport unit 81, with X-rays from above. The X-ray detector 82 detects the X-rays that have been emitted from the X-ray tube 10 and passed through the inspection object W, and outputs an X-ray detection signal, which is an electrical signal corresponding to the amount of transmitted X-rays. The signal processing unit 83 determines the quality of the inspection object W (presence or absence of foreign matter, presence or absence of defective sealing, etc.) based on the X-ray image of the inspection object W obtained from the X-ray detection signal of the X-ray detector 82. The display unit 84 is composed of various display devices, for example, a liquid crystal display, and displays the determination results of the signal processing unit 83 and the X-ray inspection image of the inspection object W.

[0041] Furthermore, the X-ray inspection apparatus 100 equipped with the X-ray tube 10 can reduce the cost of the X-ray tube 10, and therefore the equipment costs can be reduced.

[0042] In the above embodiment, the X-ray tube 10 has been described as an example of a vacuum tube, but the present invention is not limited to X-ray tubes and can be applied to other vacuum tubes such as electron guns.

[0043] As such, the present invention is not limited to the above-described embodiments, and the present invention also contemplates the mutual combination of the various components of the embodiments, as well as modifications and applications by those skilled in the art based on the description in the specification and well-known techniques, and these modifications and applications are included in the scope of protection sought.

[0044] As described above, the present specification discloses the following: (1) A vacuum tube that emits electrons from a filament located within a vacuum region, a non-conductive member that constitutes a part of a vacuum vessel that forms the vacuum region; At least three conductive rods supported by the non-conductive member and extending between the vacuum region and the outside; Equipped with the filament is connected to the conductive rod and energized; A vacuum tube, wherein at least one of the plurality of conductive rods has a screw structure. With this vacuum tube configuration, various components that require current can be attached by screwing them to at least one conductive rod with a threaded structure. This reduces the number of parts required to attach the components, thereby reducing costs. Furthermore, components that require current can be attached by using a structure in which only the conductive rod is airtightly joined to the non-conductive component. Therefore, compared to a structure in which the component itself is airtightly joined to the non-conductive component, the joining distance can be shortened, reducing manufacturing costs.

[0045] (2) The vacuum tube according to (1), wherein a Wehnelt that controls electrons emitted from the filament is screwed onto the conductive rod having a screw structure. In a vacuum tube with this configuration, the Wehnelt, which controls the electrons emitted from the filament, can be easily attached by screwing it onto a conductive rod having a threaded structure, and can be supported in a state where it can be electrically connected.

[0046] (3) The Wehnelt has a mounting wall portion that is screwed to the conductive rod and a wall body that is attached to the mounting wall portion, The vacuum tube according to (2), wherein the wall has a slit for accommodating the filament and is attached displaceably relative to the mounting wall. With a vacuum tube of this configuration, the wall body having the slit for accommodating the filament can be attached by adjusting its position relative to the mounting wall, thereby enabling the slit, which is important for controlling electrons, to be positioned accurately relative to the filament.

[0047] (4) A vacuum tube described in any one of (1) to (3), in which terminals at both ends of the molecular adsorption member are connected to the conductive rod having a screw structure and the conductive rod without a screw structure, respectively. In a vacuum tube of this configuration, the terminals on both ends of the molecular adsorption member are connected to the conductive rod, so that power can be supplied from the conductive rod to the molecular adsorption member to adsorb gas within the vacuum region, thereby increasing the degree of vacuum in the vacuum region.

[0048] (5) In any one of the vacuum tubes (1) to (4), a target that is irradiated with electrons emitted from the filament; a window portion through which X-rays emitted when the target is irradiated with electrons pass; An X-ray tube comprising: With an X-ray tube of this configuration, the number of parts can be reduced, making it possible to reduce costs.

[0049] (6) The X-ray tube according to (5) that irradiates X-rays onto the transported inspection object (W); an X-ray detector (82) for detecting X-rays transmitted through the object to be inspected; and a signal processing unit (83) that inspects the object to be inspected based on image information obtained by the X-ray detector. According to the X-ray inspection apparatus having this configuration, since it is equipped with an X-ray tube that can be reduced in cost, it is possible to reduce the equipment costs. [Explanation of symbols]

[0050] 10 X-ray tube (vacuum tube) 11 Vacuum container 21 Filament support part (non-conductive member) 22 filaments 23 Wehnelt 31 Filament electrode (conductive rod) 32 Wehnelt electrode (conductive rod) 33 screw hole (screw structure) 51 Mounting wall 55 Wall 56 Slit 59 Molecular adsorption material 59a terminal 63 Target 72 Window 100 X-ray inspection equipment Av vacuum area

Claims

1. A vacuum tube (10) that emits electrons from a filament (22) provided in a vacuum region (Av), a non-conductive member (21) that constitutes a part of a vacuum vessel (11) that forms the vacuum region; At least three conductive rods (31, 32) supported by the non-conductive member and extending between the vacuum region and the outside; Equipped with the filament is connected to the conductive rod and energized; At least one of the plurality of conductive rods has a screw structure (33). Vacuum tube.

2. A Wehnelt (23) that controls the electrons emitted from the filament is screwed onto the conductive rod having a screw structure.

2. The vacuum tube of claim 1.

3. The Wehnelt has a mounting wall portion (51) that is screwed to the conductive rod, and a wall body (55) that is attached to the mounting wall portion, The wall body has a slit (56) in which the filament is accommodated and is attached to the attachment wall portion so as to be displaceable relative to the attachment wall portion.

3. The vacuum tube according to claim 2.

4. Terminals (59a) at both ends of the molecular adsorption member (59) are connected to the conductive rod with a screw structure and the conductive rod without a screw structure, respectively.

2. The vacuum tube of claim 1.

5. The vacuum tube according to any one of claims 1 to 4, a target (63) that is irradiated with electrons emitted from the filament; a window portion (72) through which X-rays emitted when the target is irradiated with electrons pass; Equipped with X-ray tube (10).

6. an X-ray tube according to claim 5 that irradiates an X-ray onto an object to be inspected (W) being transported; an X-ray detector (82) for detecting X-rays transmitted through the object to be inspected; a signal processing unit (83) that inspects the object to be inspected based on image information obtained by the X-ray detector, An X-ray inspection device (100).

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