Cold cathode x-ray tube and imaging device thereof

Abstract

The application discloses a cold cathode X-ray tube and an imaging device thereof, and relates to the field of field emission technology. The cold cathode X-ray tube comprises a vacuum tube shell, a cold cathode field emitter encapsulated in the vacuum tube shell and used for emitting an electron beam, a control grid arranged in front of the cold cathode field emitter and used for controlling the on-off and initial intensity of the electron beam, an electrostatic deflection system arranged at one end of the control grid away from the cold cathode field emitter and used for generating an electrostatic field to cause the electron beam emitted through the control grid to be deflected by a set angle, an anode target arranged on a bombardment path of the deflected electron beam to generate X-rays through bombardment of the electron beam, and an X-ray emission window arranged on one side of the anode target and capable of emitting the generated X-rays. The cold cathode X-ray tube and the imaging device thereof have the advantages that the cathode has a long service life, the electron beam is stable and controllable, and the equipment has a small size.

Description

Technical Field

[0001] This invention relates to the field of field emission technology, and in particular to a cold cathode X-ray tube and its imaging device. Background Technology

[0002] As a core component in fields such as medical imaging and industrial inspection, the performance of X-ray tubes directly determines image quality, equipment reliability, and application adaptability. With the rapid development of mobile medical imaging equipment, the market has placed stringent demands on X-ray tubes for miniaturization, lightweight design, long lifespan, and image stability. Traditional hot cathode X-ray tubes, due to their preheating requirements, large size, and high power consumption, are difficult to meet the needs of mobile equipment. In contrast, cold cathode X-ray tubes (such as field emission cathode X-ray tubes) have become a research hotspot and development direction in this field due to their potential advantages of instantaneous start-up, no preheating required, and compact structure.

[0003] The core advantage of cold cathode X-ray tubes stems from the field emission characteristics of their nanoscale emitters (such as carbon nanotubes (CNTs) and Spindt cones), which can rapidly generate electron beams under low-voltage drive without the need for complex heating devices, thus enabling miniaturization of the equipment. However, their commercialization has long been constrained by two key technological bottlenecks, severely impacting the practicality and widespread applicability of the devices: First, ion bombardment leads to cathode failure: positive ions generated by the ionization of residual gas inside the tube bombard and physically sputter the fragile nanoscale cathode emitter (such as CNTs and Spindt cones) in the opposite direction under a high voltage electric field, resulting in rapid decay of emission performance and short device life.

[0004] Secondly, there are challenges in electron beam control and focusing: In the traditional straight-through structure, it is difficult to control the stability of the electron beam and the focal spot size, which affects the stability of X-ray output and image quality.

[0005] In the existing technology, neither the straight-through structure of the traditional cold cathode X-ray tube nor various improved schemes have been able to solve the problems of short cathode life caused by ion bombardment and precise control of electron beam, and they also have defects such as complex structure and failure to meet the miniaturization requirements.

[0006] In summary, there is an urgent need to design a technical solution that has a long lifespan, stable beam current, and compact structure. Summary of the Invention

[0007] The purpose of this invention is to provide a cold cathode X-ray tube and its imaging device to solve the problems existing in the prior art, thereby achieving a long cathode life, stable and controllable electron beam, and small device size.

[0008] To achieve the above objectives, the present invention provides the following solution: This invention provides a cold cathode X-ray tube, comprising: Vacuum tube shell; A cold cathode field emitter, encapsulated within the vacuum tube shell, is used to emit an electron beam; A control gate, located in front of the cold cathode field emitter, is used to control the on / off state and initial intensity of the electron beam; An electrostatic deflection system is disposed at the end of the control gate away from the cold cathode field emitter to generate an electrostatic field so that the direction of motion of the electron beam emitted through the control gate is deflected by a set angle. An anode target is positioned in the bombardment path of the deflected electron beam to generate X-rays through electron beam bombardment; and An X-ray exit window is located on one side of the anode target and is capable of emitting the X-rays generated by the bombardment.

[0009] The cold cathode X-ray tube of this invention integrates the cold cathode field emitter, control grid, electrostatic deflection system, anode target, and X-ray exit window into a vacuum tube shell, resulting in a compact structure and small overall device size. This invention combines the control grid with an electrostatic deflection reflective structure, creating a unique electron and ion movement path. After electrons are emitted from the cold cathode field emitter, they are first precisely modulated by the control grid, then deflected at a specific angle by the electrostatic deflection system before bombarding the anode target to generate X-rays. The electron beam is precisely controllable, while the positive ions generated during operation, due to their high inertia, cannot follow the curved path of the electrons and directly strike the inner wall of the vacuum tube shell for neutralization. This fundamentally avoids damage to the cold cathode field emitter caused by ion bombardment, thus improving cathode lifespan.

[0010] In one embodiment, the electrostatic deflection system causes the electron beam emitted from the control gate to deflect by an angle greater than 60 degrees, and in a preferred embodiment, the deflection angle is 90 degrees.

[0011] In one embodiment, the cold cathode field emitter is a carbon nanotube film, graphene, or a metal micro-cone array.

[0012] In one embodiment, the electrostatic deflection system includes an arc-shaped electrostatic electrode plate.

[0013] In one embodiment, the electrostatic deflection system includes an electrostatic lens group, which is composed of multiple independent electrodes and can dynamically adjust the deflection angle and focusing of the electron beam by adjusting the voltage of each electrode.

[0014] In one embodiment, the device further includes a metal base on which the anode target is disposed, and the metal base is connected to a heat sink outside the vacuum tube housing.

[0015] In one embodiment, the anode target is a tungsten film or a molybdenum film deposited on the metal substrate.

[0016] The present invention also provides a cold cathode X-ray tube imaging device, including an imaging device body, wherein the cold cathode X-ray tube as described above is disposed within the imaging device body.

[0017] The present invention achieves the following technical effects compared to the prior art: The cold cathode X-ray tube of this invention integrates the cold cathode field emitter, control grid, electrostatic deflection system, anode target, and X-ray exit window into a vacuum tube shell, resulting in a compact structure and small overall device size. This invention combines the control grid with an electrostatic deflection reflective structure, creating a unique electron and ion movement path. After electrons are emitted from the cold cathode field emitter, they are first precisely modulated by the control grid, then deflected at a specific angle by the electrostatic deflection system before bombarding the anode target to generate X-rays. The electron beam is precisely controllable, while the positive ions generated during operation, due to their high inertia, cannot follow the curved path of the electrons and directly strike the inner wall of the vacuum tube shell for neutralization. This fundamentally avoids damage to the cold cathode field emitter caused by ion bombardment, thus improving cathode lifespan. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of the cold cathode X-ray tube arrangement in one or more embodiments of the present invention.

[0020] In the diagram: 1-Cold cathode field emitter, 2-Control grid, 3-Electrostatic deflection system, 4-Anode target, 5-Electron beam. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] The purpose of this invention is to provide a cold cathode X-ray tube and its imaging device to solve the problems existing in the prior art, thereby achieving a long cathode life, stable and controllable electron beam, and small device size.

[0023] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0024] In existing cold cathode X-ray tubes, the positive ions generated by the ionization of residual gas inside the tube bombard and physically sputter the fragile nanoscale cathode emitter under a high-voltage electric field, leading to rapid decay of emission performance and short device lifespan. In traditional straight-through structures, electron beam stability and focal spot size control are difficult, affecting the stability of X-ray output and image quality. To address the aforementioned problems, the first objective of this invention is to provide a cold cathode X-ray tube, such as... Figure 1 As shown, the device includes a vacuum tube shell, a mature structure not illustrated in the figure. The vacuum tube shell integrates a cold cathode field emitter 1, a control grid 2, an electrostatic deflection system 3, and an anode target 4, separating the high-voltage anode region from the cathode region. This facilitates electrical insulation and heat dissipation design, while avoiding the use of bulky magnets, laying the structural foundation for miniaturization and weight reduction of the entire cold cathode X-ray tube head. The cold cathode field emitter 1, encapsulated within the vacuum tube shell, is used to emit an electron beam 5. The control grid 2 is located in front of the cold cathode field emitter 1 and is used to control the on / off state and initial intensity of the electron beam 5. The electrostatic deflection system 3 is located at the end of the control grid 2 furthest from the cold cathode field emitter 1, generating an electrostatic field to deflect the electron beam 5 emitted through the control grid 2 at a predetermined angle. The anode target 4 is positioned on the deflected bombardment path of the electron beam 5 to generate X-rays through bombardment. The anode target 4 has an X-ray exit window in the X-ray exit direction to allow the generated X-rays to exit. The cold cathode X-ray tube of this invention integrates the cold cathode field emitter 1, control grid 2, electrostatic deflection system 3, anode target 4, and X-ray exit window into a vacuum tube shell, resulting in a compact structure and small overall device size. This invention combines the control grid 2 with an electrostatic deflection reflective structure, creating a unique electron and ion movement path. After electrons are emitted from the cold cathode field emitter 1, they are first precisely modulated by the control grid 2, then deflected at a specific angle by the electrostatic deflection system 3 before bombarding the anode target 4 to generate X-rays. The electron beam 5 is precisely controllable. Meanwhile, the positive ions generated during operation, due to their high inertia, cannot follow the curved path of the electrons and directly strike the inner wall of the vacuum tube shell for neutralization. This fundamentally avoids damage to the cold cathode field emitter 1 from ion bombardment, improving cathode lifespan. The cold cathode X-ray tube of this invention is suitable for mobile medical imaging equipment with high requirements for size, weight, and image stability, such as orthopedic C-arms.

[0025] In one embodiment, the electrostatic deflection system 3 can deflect the direction of the electron beam 5 emitted from the control gate 2 by an angle greater than 60 degrees. In a preferred embodiment, the electron beam 5 is deflected by an angle of 90 degrees, forming an asymmetric electron and ion path. The electrostatic deflection system 3 produces a selective filtering effect on electrons and ions. Electrons with extremely small mass and flexibility can be deflected by the electric field at a set angle; while positive ions with huge mass move basically along their original direction (straight line) due to their great inertia, and eventually collide with and neutralize the inner wall of the vacuum tube shell or the special ion collecting electrode, and cannot return to the cathode region, thereby eliminating the main failure mechanism of ion bombardment of the cathode.

[0026] In one embodiment, the electrostatic deflection system 3 includes an arc-shaped electrostatic electrode plate. In another embodiment, the electrostatic deflection system 3 includes an electrostatic lens group composed of multiple independent electrodes, which can dynamically adjust the deflection angle and focus of the electron beam 5 by adjusting the voltage of each electrode. The control gate 2 performs initial switching and coarse adjustment of the electron beam 5, while the electrostatic deflection system 3 performs fine adjustment and focusing of the electron beam 5 to ensure that the electron beam 5 can bombard the surface of the anode target 4 at the optimal angle and focus, forming a small and stable focal point.

[0027] In one embodiment, a metal base is also provided. The cold cathode field emitter 1 is a carbon nanotube film, graphene, or a metal micro-tip array. The anode target 4 is a tungsten film or molybdenum film deposited on the metal base. The anode target 4 is deposited on the metal base, and the metal base is connected to the heat sink outside the vacuum tube shell to form an efficient heat dissipation path.

[0028] In operation, the cold cathode X-ray tube of this invention first applies a pulsed voltage to the control grid 2 to extract the electron beam 5 from the cold cathode field emitter 1. The electron beam 5 enters the electrostatic deflection system 3, where the applied deflection voltage causes the electron beam 5 to deflect 90 degrees, precisely bombarding the anode target 4, generating X-rays that exit through the X-ray exit window. The positive ions generated during operation, due to their large mass, cannot be deflected by the electrostatic deflection system 3 and move in a straight line under their inertia, impacting the inner wall of the vacuum tube and being neutralized. The heat generated by the anode is directly conducted to the tube's heat sink through the metal base under the anode target 4 and rapidly dissipated.

[0029] The second objective of this invention is to provide a cold cathode X-ray tube imaging device, comprising an imaging device body, within which a cold cathode X-ray tube is housed. Through the arrangement of the cold cathode field emitter 1, control grid 2, electrostatic deflection system 3, and anode target 4, positive ions are physically isolated from impacting the cold cathode, fundamentally solving the core failure problem of the cold cathode. The expected lifespan is more than an order of magnitude longer than that of traditional cold cathode X-ray tubes. The dual regulation of the control grid 2 and the electrostatic deflection system 3 ensures the precise stability of the electron beam 5 and the stability of the focal spot, thereby producing high-quality X-ray images with low noise and no drift, making it particularly suitable for medical diagnosis. This invention employs a fully electrostatic design, eliminating the need for electromagnets. Its compact structure significantly reduces the size and weight of the X-ray tube head and the entire C-arm, improving its mobility and ease of operation. Compared to the complex magnetic deflection schemes in the prior art, the electrostatic deflection system 3 of this invention has a relatively simple structure, low power consumption, and superior manufacturing and operating costs, while also offering higher reliability.

[0030] Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of this invention. Furthermore, those skilled in the art will recognize that, based on the ideas of this invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this invention.

Claims

1. A cold cathode X-ray tube, characterized in that: include: Vacuum tube shell; A cold cathode field emitter, encapsulated within the vacuum tube shell, is used to emit an electron beam; A control gate, located in front of the cold cathode field emitter, is used to control the on / off state and initial intensity of the electron beam; An electrostatic deflection system is disposed at the end of the control gate away from the cold cathode field emitter to generate an electrostatic field so that the direction of motion of the electron beam emitted through the control gate is deflected by a set angle. An anode target is placed in the bombardment path of the deflected electron beam to generate X-rays through electron beam bombardment. as well as An X-ray exit window is located on one side of the anode target and is capable of emitting the X-rays generated by the bombardment.

2. The cold cathode X-ray tube according to claim 1, characterized in that: The electrostatic deflection system causes the electron beam emitted from the control gate to deflect by an angle greater than 60 degrees.

3. The cold cathode X-ray tube according to claim 1, characterized in that: The cold cathode field emitter is a carbon nanotube film, graphene, or a metal micro-cone array.

4. The cold cathode X-ray tube according to claim 1, characterized in that: The electrostatic deflection system includes an arc-shaped electrostatic electrode plate.

5. The cold cathode X-ray tube according to claim 1, characterized in that: The electrostatic deflection system includes an electrostatic lens group, which is composed of multiple independent electrodes and can dynamically adjust the deflection angle and focusing of the electron beam by adjusting the voltage of each electrode.

6. The cold cathode X-ray tube according to claim 1, characterized in that: It also includes a metal base, on which the anode target is disposed, and the metal base is connected to a heat sink outside the vacuum tube shell.

7. The cold cathode X-ray tube according to claim 6, characterized in that: The anode target is a tungsten film or a molybdenum film deposited on the metal substrate.

8. A cold cathode X-ray tube imaging device, characterized in that: It includes an imaging device body, wherein the imaging device body is provided with a cold cathode X-ray tube as described in any one of claims 1 to 7.

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