X-ray tube cathode assembly and X-ray tube

Abstract

The utility model provides an X-ray tube cathode assembly and an X-ray tube, the X-ray tube cathode assembly comprises a metal cathode sealing member, a plurality of metal pins and a ceramic pedestal, the metal cathode sealing member is provided with an exhaust through hole and a plurality of core column through holes, and the side wall of each core column through hole is provided with a first annular thin wall layer; a second annular thin-wall layer is arranged on the side wall of the metal pin; an upper end face metallization layer is arranged on the upper end face of the ceramic base, a lower end face metallization layer is arranged on the lower end face of the ceramic base, a penetrating hole is formed in the ceramic base, the upper end face metallization layer is welded to the first annular thin-wall layer, the lower end face metallization layer is welded to the second annular thin-wall layer, and the metal pins penetrate through the penetrating hole and the first annular thin-wall layer. The upper end face and the lower end face of the ceramic base are welded to the first annular thin-wall layer and the second annular thin-wall layer respectively, stress release is facilitated, the air leakage probability is reduced, and the device stability is improved; and the ceramic base is used as an insulator for welding the metal cathode sealing piece and the metal pin, so that the ceramic strength is higher, and the air leakage probability is further reduced.

Description

Technical Field

[0001] The utility model belongs to the technical field of X-ray tubes and relates to an X-ray tube cathode assembly and an X-ray tube. Background Art

[0002] An X-ray tube is a device that generates X-rays. Its main working principle is that the electrons emitted by the cathode in a vacuum bombard the anode target under the action of a high-voltage electric field, thereby emitting X-rays. Therefore, an X-ray tube is mainly composed of a cathode, an electron focusing structure, an anode target, and a tube shell structure that ensures vacuum and insulation. A core pin is set at the cathode of the X-ray tube to energize the filament (electron gun), the electron focusing structure, etc., and insulation must be ensured between the core pins.

[0003] At present, X-ray tubes usually use glass shells and glass cores or use glass beads to sinter to achieve insulation sealing between the core and metal. The disadvantages of glass sintering are: 1) The shape of the glass sintered tube is difficult to control and the dimensional accuracy is poor; 2) It has high requirements for equipment and personnel, which is not conducive to mass production; 3) The strength of glass is poor and it is easy to leak after collision and vibration; 4) Glass is usually formed in one time and cannot be welded, which limits the feasibility of structural design and modification.

[0004] Therefore, how to provide an X-ray tube cathode assembly and an X-ray tube to improve the refinement and uniformity of the X-ray tube structure, reduce the probability of gas leakage, and increase the stability and reliability of the device has become a technical problem that needs to be urgently solved by those skilled in the art. Utility Model Content

[0005] In view of the above-mentioned shortcomings of the prior art, the purpose of the present invention is to provide an X-ray tube cathode assembly and an X-ray tube, which are used to solve the problems of poor stability and reliability of the X-ray tube structure and easy leakage in the prior art.

[0006] In order to achieve the above-mentioned object and other related objects, the utility model provides an X-ray tube cathode assembly, comprising:

[0007] A metal cathode sealing member, wherein the metal cathode sealing member is provided with an exhaust through hole and a plurality of core column through holes which vertically penetrate the metal cathode sealing member, and a first annular thin-wall layer is provided on the side wall of the core column through hole;

[0008] A plurality of metal pins, wherein the side walls of the metal pins are provided with a second annular thin-wall layer;

[0009] A ceramic base, wherein the upper end surface of the ceramic base is provided with an upper end surface metallization layer, the lower end surface of the ceramic base is provided with a lower end surface metallization layer, the ceramic base is provided with an insertion hole vertically penetrating the ceramic base, the upper end surface metallization layer is welded to the first annular thin-walled layer, the lower end surface metallization layer is welded to the second annular thin-walled layer, the metal pin passes through the insertion hole and the first annular thin-walled layer, and the metal pin does not contact the first annular thin-walled layer.

[0010] Optionally, a metal exhaust pipe is further included, and the metal exhaust pipe is welded to the exhaust through hole.

[0011] Optionally, a non-evaporable getter is further included, one end of the non-evaporable getter is welded to one of the metal pins, and the other end of the non-evaporable getter is welded to the metal cathode sealing member.

[0012] Optionally, a filament is further included, with two ends of the filament connected to different metal pins.

[0013] Optionally, the number of the core column through holes is four, the number of the metal pins is four, and the four metal pins are inserted into the core column through holes in a one-to-one correspondence.

[0014] Optionally, it further comprises a cathode focusing electrode, the bottom surface of which is welded to the metal cathode sealing component, and the bottom surface of which is arranged around the periphery of the plurality of metal pins.

[0015] The utility model also provides an X-ray tube, wherein the X-ray tube comprises any one of the above-mentioned X-ray tube cathode components.

[0016] As described above, in the X-ray tube cathode assembly and the X-ray tube of the utility model, the upper and lower end surfaces of the ceramic base are welded to the first annular thin-walled layer and the second annular thin-walled layer respectively, which is conducive to releasing stress, reducing the probability of leakage, and improving the stability and reliability of the device; and, the ceramic base is used as an insulator to weld the metal cathode sealing part and the metal pin, the ceramic has higher strength, better vibration resistance and anti-drop performance, and stronger resistance to thermal shock, which further reduces the probability of leakage and improves product performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 Shown is a cross-sectional view of an X-ray tube cathode assembly according to the first embodiment of the present invention.

[0018] Figure 2 Shown is a schematic diagram of welding filaments of an X-ray tube cathode assembly according to the first embodiment of the present invention.

[0019] Figure 3Shown is a cross-sectional view of the cathode focusing electrode welded to the cathode assembly of an X-ray tube according to the first embodiment of the present invention.

[0020] Figure 4 Shown is a schematic diagram of an X-ray tube according to a second embodiment of the present invention.

[0021] Component number description

[0022] 1 Metal cathode sealing parts

[0023] 10 Core through hole

[0024] 11 First annular thin wall layer

[0025] 2 metal pins

[0026] 20 Second annular thin wall layer

[0027] 3 Ceramic base

[0028] 4 Metal exhaust pipe

[0029] 5 Filament

[0030] 6 Non-evaporable getters

[0031] 7 Cathode focusing electrode

[0032] 8 Tube Shell

[0033] 9 Anode

[0034] 10 Anode focusing electrode

[0035] 11 Anode adapter

[0036] 12 Cathode adapter DETAILED DESCRIPTION

[0037] The following is an explanation of the implementation of the present invention through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific implementations, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention.

[0038] For example, when describing the embodiments of the present invention in detail, for the sake of convenience, the cross-sectional diagrams showing the device structure will not be partially enlarged according to the general scale, and the schematic diagrams are only examples, which should not limit the scope of protection of the present invention. In addition, in actual production, the three-dimensional dimensions of length, width and depth should be included.

[0039] In the context of the present application, a structure in which a first feature is described as being "above" a second feature may include embodiments in which the first feature and the second feature are formed in direct contact, and may also include embodiments in which additional features are formed between the first feature and the second feature, such that the first feature and the second feature may not be in direct contact.

[0040] See also Figures 1 to 4 It should be noted that the illustrations provided in this embodiment are only used to schematically illustrate the basic concept of the utility model, and the drawings only show the components related to the utility model rather than the number, shape and size of the components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed arbitrarily, and the component layout may also be more complicated.

[0041] Embodiment 1

[0042] This embodiment provides an X-ray tube cathode assembly. Figure 1 The X-ray tube cathode assembly includes a metal cathode package 1, a plurality of metal pins 2 and a ceramic base 3. The metal cathode sealing member 1 is provided with an exhaust through hole and a plurality of core column through holes 10 vertically penetrating the metal cathode sealing member 1, and the side wall of the core column through hole 10 is provided with a first annular thin-walled layer 11; the side wall of the metal pin 2 is provided with a second annular thin-walled layer 20; the upper end surface of the ceramic base 3 is provided with an upper end surface metallization layer, the lower end surface of the ceramic base 3 is provided with a lower end surface metallization layer, and the ceramic base 3 is provided with an interpenetrating hole vertically penetrating the ceramic base 3, the upper end surface metallization layer is welded to the first annular thin-walled layer 11, the lower end surface metallization layer is welded to the second annular thin-walled layer 20, the metal pin 2 passes through the interpenetrating hole and the first annular thin-walled layer 11, and the metal pin 2 does not contact the first annular thin-walled layer 11.

[0043] As an example, the material of the metal cathode sealing component 1 is Kovar alloy 4J34, and the metal cathode sealing component 1 is in a cylindrical structure. The exhaust through hole is provided at the center of the metal cathode sealing component 1, and four core column through holes 10 are evenly distributed around the exhaust through hole; the side wall of the core column through hole 10 is provided with the first annular thin-walled layer 11, and the first annular thin-walled layer 11 extends upward from the lower surface of the core column through hole 10. Preferably, the metal cathode sealing component 1 and the first annular thin-walled layer 11 are integrally formed. Moreover, compared with the ceramic cathode sealing component, the metal cathode sealing component 1 of this embodiment is easy to weld, which increases the design diversity and redundancy of the cathode structure.

[0044] As an example, the metal pin 2 is made of Kovar alloy 4J34, and there are four metal pins 2, which correspond one to one to the four core column through holes 10. The metal pin 2 is processed into a metal rod with the second annular thin-walled layer 20 by a CNC machine tool, and the longitudinal section of the metal pin 2 is a "cross" structure.

[0045] As an example, the material of the ceramic base 3 is alumina ceramic A-95, and the upper and lower end surfaces of the ceramic base 3 are metallized to form the upper end surface metallization layer and the lower end surface metallization layer; specifically, in this embodiment, the Mo-Mn method is used to metallize the upper and lower end surfaces of the ceramic base 3. The ceramic base 3 is provided with an interpenetrating hole that vertically penetrates the ceramic base 3, and the ceramic base 3 is cylindrical.

[0046] As an example, the metal pin 2 is not in contact with the first annular thin-walled layer 11 , that is, the hole center diameter of the first annular thin-walled layer 11 is larger than the diameter of the metal pin 2 , and the metal pin 2 is insulated and isolated from the metal cathode sealing component 1 .

[0047] In the present application, the upper and lower end faces of the ceramic base 3 are welded to the first annular thin-walled layer 11 and the second annular thin-walled layer 20 respectively, which is conducive to releasing stress, reducing the probability of leakage, and improving the stability and reliability of the device; and, the ceramic base 3 is used as an insulator to weld the metal cathode sealing part 1 and the metal pin 2, and the ceramic strength is higher, the vibration and anti-drop performance are better, and the thermal shock resistance is stronger, which further reduces the probability of leakage; in addition, the ceramic processing accuracy can be very high, which improves the fineness of the cathode structure and helps to improve product performance; at the same time, the ceramic processing and welding consistency is high, reducing dependence on equipment and personnel.

[0048] As an example, a metal exhaust pipe 4 is also included, and the metal exhaust pipe 4 is welded to the exhaust through hole, and is used to exhaust and evacuate the X-ray tube cavity. The metal exhaust pipe 4 is a thin-walled metal pipe, and the material is required to be pure, soft, and easy to seal. In this embodiment, the metal exhaust pipe 4 is made of oxygen-free copper, and the metal exhaust pipe 4 and the exhaust through hole are welded by vacuum brazing.

[0049] Preferably, in this embodiment, the metal cathode sealing component 1, the ceramic base 3, the metal pin 2 and the metal exhaust pipe 4 are vacuum brazed in one step at the same time without the need for a pre-oxidation step, which is conducive to mass production. During welding, AgCu28 annular solder sheets or solder wires of corresponding sizes can be selected as solder based on the welding surface.

[0050] As an example, see Figure 2, further comprising a filament 5, wherein both ends of the filament 5 are connected to different metal pins 2, wherein the filament 5 is welded to the metal pin 2 by resistance welding or laser welding, and a heating direct current is provided to the filament 5 through the metal pin 2, so that the filament 5 emits electrons. In this embodiment, the number of the filaments 5 is two, and the two filaments 5 are welded to the four metal pins 2.

[0051] As an example, a non-evaporable getter 6 is also included, and one end of the non-evaporable getter 6 is welded to one of the metal pins 2 by resistance welding, and the other end of the non-evaporable getter 6 is welded to the metal cathode sealing member 1. When the cavity of the X-ray tube is exhausted, the non-evaporable getter 6 is activated by applying electricity between the metal cathode sealing member 1 and the metal pin 2 to further ensure the vacuum degree of the cavity of the X-ray tube. In this embodiment, a voltage is applied to the metal cathode sealing member 1 through the metal exhaust pipe 4, and there is no need to specially design pins for the metal cathode sealing member 1, which improves the redundancy of the design and is also conducive to reducing the product size.

[0052] As an example, see Figure 3 , further comprising a cathode focusing electrode 7, the bottom surface of which is welded to the top surface of the metal cathode sealing component 1, and the bottom surface of which is arranged around the periphery of the plurality of metal pins 2. The cathode focusing electrode 7 is used to focus the electron beam. In this embodiment, the cathode focusing electrode 7 is made of stainless steel 316L, the surface of which is polished, and the bottom surface of the cathode focusing electrode 7 is welded to the metal cathode sealing component 1 by resistance welding or laser welding.

[0053] As described above, in the X-ray tube cathode assembly of the present embodiment, the upper and lower end surfaces of the ceramic base are welded to the first annular thin-walled layer and the second annular thin-walled layer respectively, which is conducive to releasing stress, reducing the probability of gas leakage, and improving the stability and reliability of the device; and, the ceramic base is used as an insulator to weld the metal cathode sealing part and the metal pin, the ceramic has higher strength, better vibration resistance and anti-drop performance, and stronger resistance to thermal shock, which further reduces the probability of gas leakage and improves product performance.

[0054] Embodiment 2

[0055] This embodiment provides an X-ray tube, the X-ray tube comprising the X-ray tube cathode assembly described in Embodiment 1. Figure 4 , further comprising an anode assembly and a tube shell 8, wherein the tube shell 8 is used for sealingly connecting the cathode assembly and the anode assembly.

[0056] As an example, the anode assembly includes an anode 9 and an anode focusing electrode 10, wherein the anode 9 is made of a beryllium metal sheet, and a layer of metal such as gold, silver, tungsten, rhodium, etc. is plated on the vacuum side thereof using a magnetron sputtering method as an anode target, and the top end of the anode focusing electrode 10 is welded to the anode 9, and the bottom end of the anode focusing electrode 10 faces the cathode assembly.

[0057] As an example, the tube shell 8 of the X-ray tube is made of insulating material, for example, ceramic or glass, etc. In this embodiment, the tube shell 8 is made of alumina ceramic A-99, and the upper and lower end surfaces of the tube shell 8 are metallized layers. The upper end surface of the tube shell 8 is brazed with Kovar alloy to form an anode adapter 11, and the tube shell 8 is welded to the anode assembly through the anode adapter 11. The lower end surface of the tube shell 8 is brazed with Kovar alloy to form a cathode adapter 12, and the tube shell 8 is welded to the cathode assembly through the cathode adapter 12. Preferably, the anode target, the tube shell 8, the anode adapter 11, and the cathode adapter 12 are vacuum brazed in one step at the same time, and the solder is AgCu28; the cathode assembly and the cathode adapter 12 are welded using a vacuum electron beam or laser.

[0058] As an example, in this embodiment, the X-ray tube is a closed X-ray tube. In other examples, the X-ray tube may also be an open X-ray tube, which is not limited to this embodiment. In this embodiment, the anode target is a transmission target. In other examples, the anode target may also be a reflection target, which is not limited to this embodiment.

[0059] In summary, in the X-ray tube cathode assembly and X-ray tube of the utility model, the upper and lower end surfaces of the ceramic base are respectively welded to the first annular thin-walled layer and the second annular thin-walled layer, which is conducive to releasing stress, reducing the probability of gas leakage, and improving the stability and reliability of the device; and, the ceramic base is used as an insulator to weld the metal cathode sealing part and the metal pin, the ceramic strength is higher, the vibration resistance and anti-drop performance are better, the thermal shock resistance is stronger, the gas leakage probability is further reduced, and the product performance is improved. Therefore, the utility model effectively overcomes various shortcomings in the prior art and has a high industrial utilization value.

[0060] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the technology may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed in the present invention shall still be covered by the claims of the present invention.

Claims

1. An X-ray tube cathode assembly, characterized in that: include: A metal cathode sealing member, wherein the metal cathode sealing member is provided with an exhaust through hole and a plurality of core column through holes which vertically penetrate the metal cathode sealing member, and a first annular thin-wall layer is provided on the side wall of the core column through hole; A plurality of metal pins, wherein the side walls of the metal pins are provided with a second annular thin-wall layer; A ceramic base, wherein the upper end surface of the ceramic base is provided with an upper end surface metallization layer, the lower end surface of the ceramic base is provided with a lower end surface metallization layer, the ceramic base is provided with an insertion hole vertically penetrating the ceramic base, the upper end surface metallization layer is welded to the first annular thin-walled layer, the lower end surface metallization layer is welded to the second annular thin-walled layer, the metal pin passes through the insertion hole and the first annular thin-walled layer, and the metal pin does not contact the first annular thin-walled layer.

2. The X-ray tube cathode assembly according to claim 1, characterized in that: It also includes a metal exhaust pipe, which is welded to the exhaust through hole.

3. The X-ray tube cathode assembly according to claim 1, characterized in that: It also includes a non-evaporable getter, one end of the non-evaporable getter is welded to one of the metal pins, and the other end of the non-evaporable getter is welded to the metal cathode sealing member.

4. The X-ray tube cathode assembly according to claim 1, characterized in that: Also included is a filament, with two ends of the filament connected to different metal pins.

5. The X-ray tube cathode assembly according to claim 1, characterized in that: The number of the core column through holes is four, the number of the metal pins is four, and the four metal pins are inserted into the core column through holes in a one-to-one correspondence.

6. The X-ray tube cathode assembly according to claim 1, characterized in that: It also includes a cathode focusing electrode, the bottom surface of which is welded to the metal cathode sealing component, and the bottom surface of which is arranged around the periphery of the plurality of metal pins.

7. An X-ray tube, characterized in that: The X-ray tube comprises the X-ray tube cathode assembly according to any one of claims 1 to 6.

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