X-ray tube flat plate filament and cathode assembly

Abstract

The invention relates to the technical field of X-ray tube manufacturing, in particular to an X-ray tube flat plate filament and a cathode assembly. Comprising a filament plate, the filament plate comprises a transmitting end face, a first metal layer is attached to the transmitting end face of the filament plate and / or a second metal layer is attached to the end face of the side, away from the transmitting end face, of the filament plate, the work function of the first metal layer is lower than the material of the filament plate, and the work function of the second metal layer is higher than the material of the filament plate. After the filament plate is electrified, electrons are emitted from one side of the emission end face to the anode target disc. The invention has the advantages of good emission characteristic and long service life.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of X-ray tube manufacturing, in particular to an X-ray tube flat filament and cathode assembly. BACKGROUND

[0002] Medical X-ray diagnostic equipment computerized tomography (CT) uses an X-ray tube assembly for X-ray photography, the X-ray tube assembly includes a tube cover and an X-ray tube, the X-ray tube is accommodated in the tube cover and radiates X-rays, the tube cover is provided with an X-ray radiation window for X-rays to pass through, and other parts of the inner wall of the tube cover are adhered with lead plates for shielding X-rays.

[0003] The X-ray tube includes a cathode, an anode target and a vacuum tube shell, the cathode is opposite to the anode target and is offset relative to the rotation axis of the anode. In the vacuum environment formed by the vacuum tube shell, when a high voltage is applied between the cathode and the anode target, the cathode emits electrons, the electrons are accelerated to collide with the target surface of the anode, the anode target radiates X-rays, and the X-rays are emitted through the window on the tube shell.

[0004] The cathode system serves as an electron emission device, and the emission characteristics of the cathode filament can affect the stability of the tube current. One of the common failures of the X-ray tube is filament failure, and therefore, improving the service life of the filament can prolong the service life of the X-ray tube. SUMMARY

[0005] In order to overcome the shortcomings of the prior art, the present application provides an X-ray tube flat filament, which has the advantages of good emission characteristics and long service life.

[0006] In order to achieve the above-mentioned purpose, the present application is realized by the following technical scheme: An X-ray tube flat filament includes a filament plate, the filament plate includes an emission end face, the filament plate is attached with a first metal layer and / or a second metal layer, the first metal layer is attached to the emission end face, the work function of the first metal layer is lower than the material of the filament plate, the second metal layer is attached to the end face of the filament plate away from the emission end face, and the work function of the second metal layer is higher than the material of the filament plate. After the filament plate is powered on, electrons are emitted from the emission end face side to the anode target disc.

[0007] Further, the thickness of the first metal layer and / or the second metal layer in the X-ray tube flat filament of the present application is less than or equal to 0.01 mm.

[0008] Further, the material of the filament plate in the X-ray tube flat filament of the present application is tungsten, the material composition of the first metal layer includes at least one of tantalum and niobium, and the material composition of the second metal layer includes at least one of molybdenum and rhenium.

[0009] Furthermore, in this application, an X-ray tube flat filament has several slots arranged at intervals along the elongation direction on each of the two edges of the filament plate along the length direction. The slots penetrate the filament plate along the thickness direction, and the slots on both sides are staggered in the length direction, so that the filament plate extends in an N-shape in the length direction as a whole.

[0010] An X-ray tube cathode assembly includes the aforementioned flat filament and a cathode head, wherein the emitting end of the cathode head is provided with a focusing groove and the filament plate is disposed in the focusing groove; The filament plate has filament leads at both ends along its length, and the cathode head has a first through hole corresponding to the filament leads, with the filament leads passing through the first through hole; It also includes an insulating component, which is fixed to the end of the first through hole away from the focusing groove. The insulating component has a second through hole extending in the same direction as the first through hole. The filament lead passes through the second through hole and is fixedly connected to the insulating component. The filament lead is fixed to the cathode head by the insulating component, thereby achieving stable support for the filament lead.

[0011] As can be seen from the above technical solution, the present invention has the following beneficial effects: This invention provides a flat X-ray tube filament with a filament plate. Compared to traditional spiral coil filaments, it has a more stable structure, improving the lifespan of both the filament and the X-ray tube. Simultaneously, it effectively increases the area for thermionic emission, enhancing electron emission efficiency and increasing exposure power. By placing a low work function first metal layer on the emitting end face, electron escape is facilitated, increasing the number of thermionic electrons emitted. A high work function second metal layer is placed on the end of the filament plate away from the emitting end face. This second metal layer, facing away from the anode target disk, suppresses electron escape from that side, making the electron emission direction more concentrated. This improves the quality of electrons emitted by the flat filament, further optimizing the stability of X-ray output and imaging accuracy. Attached Figure Description

[0012] Figure 1 This is a plan view of a flat filament of an X-ray tube according to an embodiment of this application; Figure 2 This is a front plan view of a flat filament for an X-ray tube according to an embodiment of this application; Figure 3 This is a three-dimensional structural schematic diagram of a flat filament for an X-ray tube according to an embodiment of this application; Figure 4 This is a cross-sectional view of a flat filament for an X-ray tube according to an embodiment of this application.

[0013] In the diagram: 91-Filament plate; 910-Spacing groove; 911-Emitting end face; 912-Filament pin; 92-Cathode head; 921-Focusing groove; 922-First perforation; 93-Insulator; 931-Second perforation. Detailed Implementation

[0014] Example 1 Combination Figure 1 and Figure 2 The X-ray tube flat filament shown includes a filament plate 91, the filament plate 91 including an emitting end face 911, a first metal layer (not shown) and / or a second metal layer (not shown) attached to the filament plate 91, the first metal layer being attached to the emitting end face 911, the work function of the first metal layer being lower than that of the material of the filament plate 91, the second metal layer being attached to the end face of the filament plate 91 away from the emitting end face 911, the work function of the second metal layer being higher than that of the material of the filament plate 91.

[0015] Based on the above structure, the principle of a flat X-ray tube filament is as follows: After the filament plate 91 is energized, electrons are emitted from one side of the emitting end face 911 towards the anode target. Using the filament plate 91, compared to the traditional spiral coil filament, provides a more stable structure, improves the lifespan of the filament and X-ray tube, and effectively increases the area for thermionic emission, thereby improving electron emission efficiency and increasing exposure power. By setting a first metal layer with a low work function on the emitting end face 911, the number of thermionic electrons emitted is increased, which is beneficial for electron escape. Meanwhile, a second metal layer with a high work function is set at the end of the filament plate 91 away from the emitting end face 911. This second metal layer, facing away from the anode target, suppresses electron escape from that side, making the electron emission direction more concentrated. This improves the quality of electrons emitted by the flat filament, further optimizing the stability of X-ray output and imaging accuracy.

[0016] In this embodiment, the first metal layer and the second metal layer can be formed by physical vapor deposition or chemical vapor deposition.

[0017] In this embodiment, the thickness of the first metal layer and / or the second metal layer is less than or equal to 0.01 mm.

[0018] Furthermore, in this embodiment, the filament plate 91 is made of tungsten, and the work function of tungsten is typically 4.55 eV. The material composition of the first metal layer includes at least one of tantalum (Ta) and niobium (Nb), and the material composition of the second metal layer includes at least one of molybdenum (Mo) and rhenium (Re).

[0019] In this embodiment, the filament plate 91 has several slots 910 arranged at intervals along the length direction on each of its two edges along the length direction. The slots 910 penetrate the filament plate 91 along the thickness direction, and the slots 910 on both sides are staggered in the length direction, so that the filament plate 91 extends in an N-shape in the length direction.

[0020] Example 2 Combination Figure 3 and Figure 4The X-ray tube cathode assembly shown includes the flat filament of Embodiment 1, and also includes a cathode head 92. The emitting end of the cathode head 92 is provided with a focusing groove 921, and the filament plate 91 is disposed in the focusing groove 921. The filament plate 91 has filament pins 912 at both ends along its length, and the cathode head 92 has a first through hole 922 corresponding to the filament pins 912, with the filament pins 912 passing through the first through hole 922. It also includes an insulating component 93, which is fixed to the end of the first through hole 922 away from the focusing groove 921. The insulating component 93 has a second through hole 931 extending in the same direction as the first through hole 922. The filament lead 912 passes through the second through hole 931 and is fixedly connected to the insulating component 93. The filament lead 912 is fixed to the cathode head 92 by the insulating component 93, thereby achieving stable support for the filament lead 912.

[0021] The technical principles of the present invention have been described above with reference to specific embodiments. These descriptions are merely for explaining the principles of the invention and should not be construed as limiting the scope of protection of the invention in any way. Based on this explanation, those skilled in the art can conceive of other specific embodiments of the invention without creative effort, and these embodiments will all fall within the scope of protection of the present invention.

Claims

1. A flat filament for an X-ray tube, characterized in that: The lamp includes a filament plate (91), which includes an emitting end face (911). A first metal layer and / or a second metal layer are attached to the filament plate (91). The first metal layer is attached to the emitting end face (911), and the work function of the first metal layer is lower than that of the material of the filament plate (91). The second metal layer is attached to the end face of the filament plate (91) away from the emitting end face (911), and the work function of the second metal layer is higher than that of the material of the filament plate (91).

2. The flat filament of an X-ray tube according to claim 1, characterized in that: The thickness of the first metal layer and / or the second metal layer is less than or equal to 0.01 mm.

3. The flat filament of an X-ray tube according to claim 1, characterized in that: The filament plate (91) is made of tungsten, the first metal layer is composed of at least one of tantalum and niobium, and the second metal layer is composed of at least one of molybdenum and rhenium.

4. The flat filament of an X-ray tube according to claim 1, characterized in that: The filament plate (91) has several slots (910) arranged at intervals along the length direction on both edges. The slots (910) penetrate the filament plate (91) along the thickness direction. The slots (910) on both sides are staggered in the length direction, so that the filament plate (91) extends in an N-shape in the length direction.

5. An X-ray tube cathode assembly, characterized in that: The device includes the flat filament as described in claim 1, and also includes a cathode head (92), wherein the emitting end of the cathode head (92) is provided with a focusing groove (921), and the filament plate (91) is disposed in the focusing groove (921); The filament plate (91) has filament pins (912) at both ends along its length. The cathode head (92) has a first through hole (922) corresponding to the filament pins (912). The filament pins (912) are inserted into the first through hole (922). It also includes an insulating component (93), which is fixed to the end of the first through hole (922) away from the focusing groove (921). The insulating component (93) is provided with a second through hole (931) extending in the same direction as the first through hole (922). The filament lead (912) passes through the second through hole (931) and is fixedly connected to the insulating component (93).

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