KR102396948B1 - X-ray imaging device and driving method thereof - Google Patents

Abstract

The present invention relates to an X-ray imaging apparatus and a driving method thereof. More specifically, the present invention provides an electron beam generator including a plurality of nano-emitters and a cathode; a first focusing electrode for focusing the electron beam emitted from the electron beam generator; a deflector for deflecting the electron beam focused at the first focusing electrode; a limiting electrode for limiting the propagation of the electron beam deflected by the deflector; and an anode to which the electron beam is irradiated to emit X-rays. The confinement electrode includes a confinement opening through which the electron beam may pass.

Description

X-ray imaging apparatus and driving method thereof {X-RAY IMAGING DEVICE AND DRIVING METHOD THEREOF}

The present invention relates to an X-ray imaging apparatus and a driving method thereof. More particularly, the present invention relates to an X-ray imaging apparatus capable of obtaining a clear X-ray image, and a driving method thereof.

A point electron source means an electron source in which the flow of electrons starts at one point. In other words, the point electron source means an electron source in which an electron beam is generated in a very small area such as a point. When the electron beam is generated in a very small area such as a point, it is easy to focus the generated electron beam to a very small area again using an electron optical system, so there is an advantage that a fine probe beam can be made relatively easily. . When the diameter of the electron beam is small, it can be very usefully used in various applications. For example, the resolution of an electron microscope such as SEM or TEM may be improved, and a focal spot of an X-ray may be reduced, so that the resolution of an X-ray image may be improved.

An object of the present invention is to provide an X-ray imaging apparatus capable of obtaining a clear image while having a plurality of nano-emitters.

The present invention provides an electron beam generator including a plurality of nano-emitters and a cathode; a first focusing electrode for focusing the electron beam emitted from the electron beam generator; a deflector for deflecting the electron beam focused at the first focusing electrode; a limiting electrode for limiting the propagation of the electron beam deflected by the deflector; and an anode to which the electron beam is irradiated to emit X-rays, wherein the limiting electrode includes a limiting opening through which the electron beam can pass.

A gate electrode for applying an electric field to the nano-emitters may be further included.

The method may further include an image acquisition unit configured to acquire an X-ray image by using the X-ray emitted from the anode.

The deflector may include electrodes spaced apart from each other with an electron beam path through which the electron beam passes, and a voltage source for applying a voltage to the electrodes.

The deflector may include coils spaced apart from each other with an electron beam path through which the electron beam passes, and a current source providing a current to the coils.

A second focusing electrode for focusing the electron beam passing through the limiting opening may be further included.

The limiting electrode may further include an ammeter for measuring a current flowing through the limiting electrode.

The present invention provides an electron beam emitting step for emitting a plurality of electron beams from an electron beam generator; an electron beam limiting step of limiting the progress of the electron beams emitted from the electron beam generator using a limiting electrode; and an anode irradiation step of irradiating at least some of the electron beams to the anode, wherein the limiting electrode includes a limiting opening through which the electron beams can pass.

The limiting of the electron beam may include allowing one of the electron beams emitted from the electron beam generator to pass through the limiting opening.

The limiting of the electron beam may include focusing the electron beams emitted from the electron beam generator using a first focusing electrode.

The limiting of the electron beam may further include deflecting the electron beams focused at the first focusing electrode using a deflector.

The electron beam limiting step may further include obtaining a current intensity map of the limiting electrode by measuring a current flowing through the limiting electrode.

The focusing of the electron beams may include determining whether the current intensity map is clear, and controlling the focusing of the electron beams by controlling the first focusing electrode.

Adjusting the focusing of the electron beams may include adjusting the focusing of the electron beams so that a planar area of the electron beams is minimized at the same level as the lower surface of the limiting opening.

Deflecting the electron beams focused by the first focusing electrode may include controlling the deflector to correspond to the darkest spot in the current intensity map.

Controlling the deflector may include optimizing a magnitude of a voltage of a voltage source of the deflector.

Controlling the deflector may include optimizing a magnitude of a current of a current source of the deflector.

The step of irradiating the anode may include focusing the single electron beam using a second focusing electrode.

Since the X-ray imaging apparatus according to the present invention includes a deflector and a limiting aperture, one electron beam having the largest current among the electron beams generated from the plurality of nano-emitters can be irradiated to the anode, and a clear image can be obtained. can

1A and 1B are diagrams for explaining the characteristics of an electron beam generated from a nano-emitter.
2A is a view for explaining an X-ray imaging apparatus according to a comparative example of the present invention.
FIG. 2B is an enlarged view of area A of FIG. 2A .
3 is an X-ray image obtained by the X-ray imaging apparatus of FIGS. 2A and 2B .
4 is a view for explaining an X-ray imaging apparatus according to embodiments of the present invention;
5A and 5B are diagrams for explaining embodiments of a deflector.
6 is an X-ray image obtained by the X-ray imaging apparatus of FIG. 4 .
7 is a diagram for explaining an intensity map of a current measured by a limiting electrode.
8A to 8C are views for explaining a shape of an electron beam passing through a restriction opening.
9A and 9B are actual images of the current intensity map of the limiting electrode.
10 is a flowchart illustrating a method of driving an X-ray imaging apparatus according to embodiments of the present invention.
11 is a view for explaining an X-ray imaging apparatus according to embodiments of the present invention.

Advantages and features of the present invention, and methods for achieving them, will become apparent with reference to the embodiments described below in detail in conjunction with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but may be implemented in various different forms, and only these embodiments allow the disclosure of the present invention to be complete, and common knowledge in the technical field to which the present invention pertains. It is provided to fully inform the possessor of the scope of the invention, and the present invention is only defined by the scope of the claims. Like reference numerals refer to like elements throughout.

The terminology used herein is for the purpose of describing the embodiments and is not intended to limit the present invention. In this specification, the singular also includes the plural unless specifically stated otherwise in the phrase. As used herein, 'comprises' and/or 'comprising' refers to the presence of one or more other components, steps, operations and/or devices mentioned. or addition is not excluded.

Hereinafter, embodiments of the present invention will be described in detail.

1A and 1B are diagrams for explaining the characteristics of an electron beam generated from a nano-emitter.

1A and 1B , an electron beam device including a cathode 11 , first to fourth nano-emitters 13a-13d on the cathode 11 , and an anode fluorescent film 41 may be provided. . Each of the first to fourth nano-emitters 13a-13d may emit respective first to fourth electron beams 14a-14d. The first to fourth electron beams 14a - 14b may be irradiated to the anode fluorescent film 41 . The first to fourth electron beams 14a-14d may be irradiated to the anode fluorescent film 41 to form first to fourth electron beam fluorescent dots 42a to 42d in the anode fluorescent film 41 . there is. By observing the first to fourth electron beam fluorescent points 42a to 42d, characteristics of the first to fourth electron beams 14a to 14d can be identified. Each of the first to fourth electron beam fluorescent spots 42a to 42d may be formed to correspond to a focal spot of each of the first to fourth electron beams 14a to 14d. The focal spot may mean a planar area of each of the first to fourth electron beams 14a-14d irradiated to the anode fluorescent film 41 on the surface of the anode fluorescent film 41 . In other words, the focal spot may mean a planar area of the electron beam on the surface of the object to which the electron beam is irradiated.

As the voltage difference between the anode fluorescent film 41 and the cathode 11 increases, the diameter of each of the first to fourth electron beam fluorescent dots 42a to 42d may decrease. In other words, as the voltage difference between the anode fluorescent film 41 and the cathode 11 increases, the focal spot of each of the first to fourth electron beams 14a-14d irradiated to the anode fluorescent film 41 becomes smaller. can get The diameter of each of the first to fourth electron beam fluorescent dots 42a to 42d may increase as the distance between the anode fluorescent film 41 and the cathode 11 increases. The distance between the first to fourth electron beam fluorescent dots 42a to 42d may increase as the distance between the anode fluorescent film 41 and the cathode 11 increases.

FIG. 2A is a view for explaining an X-ray imaging apparatus according to a comparative example of the present invention, and FIG. 2B is an enlarged view of area A of FIG. 2A .

2A and 2B , the X-ray imaging apparatus may include an electron beam generator 10 , a gate electrode 20 , a focusing electrode 30 , an anode 40 , and an image acquisition unit 50 .

The electron beam generator 10 may include a cathode 11 , an adhesive layer 12 , and first to fourth nano-emitters 13a-13d.

First to fourth nano-emitters 13a-13d may be provided on the cathode 11 . Although the number of the nano-emitters 13a-13d is illustrated as being four, it may not be limited thereto. The cathode 11 may be grounded. The first to fourth nano-emitters 13a - 13d may be attached to the cathode 11 by the adhesive layer 12 . The first to fourth nano-emitters 13a-13d and the adhesive layer 12 may be attached on the cathode 11 through a paste printing process. The first to fourth nano-emitters 13a-13d may be planarly spaced apart from each other. The shortest distance between the first to fourth nano-emitters 13a-13d may be 1 μm to 200 μm. The first to fourth nano-emitters 13a-13d may include a conductive material. For example, each of the first to fourth nano-emitters 13a-13d may include carbon nanotubes (CNTs). The lengths of each of the first to fourth nano-emitters 13a-13d may be different from each other. Angles formed by each of the first to fourth nano-emitters 13a-13d with the upper surface of the cathode 11 may be different from each other. In other words, the inclination degree of each of the first to fourth nano-emitters 13a-13d may be different from each other.

The adhesive layer 12 may include an adhesive material. For example, the adhesive layer 12 may include a conductive paste.

A gate electrode 20 may be provided on the electron beam generator 10 . In other words, the gate electrode 20 may be provided between the electron beam generator 10 and the anode 40 . A positive voltage may be applied to the gate electrode 20 . The gate electrode 20 may include a gate opening 21 . The diameter of the gate opening 21 may be 1 μm to 500 μm. The shortest distance between the gate electrode 20 and the electron beam generator 10 may be 1 μm to 5000 μm. The shortest distance between the gate electrode 20 and the electron beam generator 10 may be 0.1 to 10 times the diameter of the gate opening 21 .

A focusing electrode 30 may be provided on the gate electrode 20 . In other words, the focusing electrode 30 may be provided between the gate electrode 20 and the anode 40 . However, the location of the focusing electrode 30 may not be limited thereto. A positive voltage may be applied to the focusing electrode 30 . The focusing electrode 30 may include a focusing opening 31 . Instead of the focusing electrode 30, an optical system (eg, an electrostatic lens or a magnetic lens) capable of focusing the electron beam may be provided.

An anode 40 may be provided on the focusing electrode 30 . In other words, the anode 40 may be provided between the focusing electrode 30 and the image acquisition unit 50 . A positive voltage may be applied to the anode 40 . The anode 40 may include an anode target and an anode electrode. The anode target may include a material that emits X-rays according to electron beam irradiation. For example, the anode target may include tungsten or molybdenum. The anode electrode may include a material having high electrical conductivity. For example, the anode electrode may include copper.

An image acquisition unit 50 may be provided on the anode 40 . The image acquisition unit 50 may acquire an X-ray image by using the X-ray emitted from the anode 40 .

When explaining the driving method of the X-ray imaging apparatus, a positive voltage may be applied to the gate electrode 20 to generate a voltage difference between the gate electrode 20 and the cathode 11 . Due to the voltage difference between the gate electrode 20 and the cathode 11, each of the first to fourth electron beams 14a-14d will be emitted from each of the first to fourth nano-emitters 13a-13a. can The first to fourth electron beams 14a-14d may be emitted from the ends of each of the first to fourth nano-emitters 13a-13d. Among the first to fourth nano-emitters 13a-13d, the first nano-emitter 13a may have the longest length, and the fourth nano-emitter 13d may have the shortest length. As the length of the nano-emitters 13a-13d increases, the voltage difference between the gate electrode 20 and the cathode 11 from which the electron beams 14a-14d starts to be emitted may be small. In other words, the voltage difference between the gate electrode 20 and the cathode 11 from which the first electron beam 14a is emitted from the first nano-emitter 13a is the fourth electron beam from the fourth nano-emitter 13d. 14d may be smaller than the voltage difference between the gate electrode 20 and the cathode 11 from which emission starts. As the diameter of the nano-emitters 13a-13d is smaller, the planar area of the emitted electron beams 14a-14d may be smaller.

A positive voltage may be applied to the anode 40 to generate a voltage difference between the anode 40 and the cathode 11 . The first to fourth electron beams 14a-14d emitted from the nano-emitters 13a-13d may be accelerated by the voltage difference between the anode 40 and the cathode 11 to travel toward the anode 40 . there is. The traveling paths of each of the first to fourth electron beams 14a-14d may be different from each other. In other words, paths in which the first to fourth electron beams 14a-14d are emitted from the nano-emitters 13a-13d to reach the anode 40 may be different from each other. While traveling in the direction of the anode 40 , some of the first to fourth electron beams 14a - 14d may overlap each other, and other portions may not overlap each other.

The first to fourth electron beams 14a - 14d may pass through the gate opening 21 of the gate electrode 20 . The gate opening 21 may have a size sufficient to allow the first to fourth electron beams 14a-14d to pass therethrough.

The first to fourth electron beams 14a - 14d passing through the gate opening 21 may pass through the focusing opening 31 of the focusing electrode 30 . The focusing opening 31 may have a size sufficient to allow the first to fourth electron beams 14a-14d to pass therethrough. While passing through the focusing opening 31 , the first to fourth electron beams 14a - 14d may be focused. By controlling the first focusing electrode 30 , the focal spots of the first to fourth electron beams 14a-14d may be adjusted to be at a minimum on the surface of the anode 40 .

The first to fourth electron beams 14a - 14d passing through the focusing opening 31 may be irradiated to the anode 40 . Each of the first to fourth electron beams 14a - 14d may have different positions to be irradiated to the anode 40 . In other words, on the surface of the anode 40, focal spots of each of the first to fourth electron beams 14a-14d may be spaced apart from each other. The first to fourth electron beams 14a to 14d may be irradiated to the anode 40 , and the first to fourth X-rays 43a to 43d may be emitted from the anode 40 . Each of the first to fourth X-rays 43a - 43d may have different positions emitted from the anode 40 . In other words, on the surface of the anode 40 , emission points of the first to fourth X-rays 43a to 43d may be spaced apart from each other.

The first to fourth X-rays 43a - 43d may travel from the anode 40 toward the image acquisition unit 50 . As the emission points of the first to fourth X-rays 43a to 43d are spaced apart from each other, as the emission points of the first to fourth X-rays 43a to 43d are spaced apart from each other, travel paths of the first to fourth X-rays 43a to 43d are separated from each other while proceeding toward the image acquisition unit 50 . can be different. In other words, some of the first to fourth X-rays 43a - 43d may overlap each other, and other portions may not overlap each other. The first to fourth X-rays 43a to 43d may be irradiated to the subject SJ disposed between the anode 40 and the image acquisition unit 50 .

The first to fourth X-rays 43a to 43d may be irradiated to the image acquisition unit 50 . The image acquisition unit 50 may acquire an X-ray image of the subject SJ. An X-ray image obtained by the first to fourth X-rays 43a to 43d having emission points spaced apart from each other may not be clear. In other words, since the X-ray image is obtained by a plurality of X-rays 43a - 43d, it may include a plurality of images that are shifted and overlap each other.

3 is an X-ray image obtained by the X-ray imaging apparatus of FIGS. 2A and 2B .

Referring to FIG. 3 , it can be seen that the subject is not clearly displayed in the X-ray image obtained by the plurality of X-rays.

4 is a diagram for explaining an X-ray imaging apparatus according to embodiments of the present invention, and FIGS. 5A and 5B are diagrams for explaining embodiments of a deflector. The same reference numerals are used for the same components described with reference to FIGS. 2A and 2B, and overlapping descriptions will be omitted.

4, 5A and 5B , the X-ray imaging apparatus includes an electron beam generator 10 , a gate electrode 20 , a first focusing electrode 30 , an anode 40 , an image acquisition unit 50 , It may include a deflector 60 , a limiting electrode 70 , and a second focusing electrode 80 .

The deflector 60 may be provided on the first focusing electrode 30 . In other words, the deflector 60 may be provided between the first focusing electrode 30 and the anode 40 . However, the position of the deflector 60 may not be limited thereto. The deflector 60 may be positioned between the first focusing electrode 30 and the gate electrode 20 , or between the gate electrode 20 and the cathode 11 (refer to FIG. 2B ). In one embodiment, the deflector 60 may be an electrostatic deflector (see FIG. 5A ). The deflector 60 may include X-axis electrodes 61a, Y-axis electrodes 61b, an X-axis voltage source 62a, and a Y-axis voltage source 62b. An electron beam path 65 may be defined by the X-axis electrodes 61a and the Y-axis electrodes 61b. The X-axis electrodes 61a may be provided on both sides of the electron beam path 65 along the X-axis. The Y-axis electrodes 61b may be provided on both sides of the electron beam path 65 along the Y-axis. The X-axis voltage source 62a applies a voltage to the X-axis electrodes 61a, so that a voltage difference may be generated between the X-axis electrodes 61a. Accordingly, an electric field may be generated along the X-axis in the electron beam path 65 between the X-axis electrodes 61a. A voltage difference may be generated between the Y-axis electrodes 61b by the Y-axis voltage source 62b applying a voltage to the Y-axis electrodes 61b. Accordingly, an electric field may be generated along the Y-axis in the electron beam path 65 between the Y-axis electrodes 61b. The electron beam passing through the electron beam path 65 may be deflected by the electric field generated along the X and Y axes. A voltage applied by the X-axis voltage source 62a may be defined as an X voltage, and a voltage applied by the Y-axis voltage source 62b may be defined as a Y voltage.

In another embodiment, the deflector 60 may be a magnetic field type deflector (see FIG. 5B ). The deflector 60 may include X-axis coils 63a, Y-axis coils 63b, an X-axis current source 64a, and a Y-axis current source 64b. An electron beam path 65 may be defined by the X-axis coils 63a and the Y-axis coils 63b. X-axis coils 63a may be provided on both sides of the electron beam path 65 along the X-axis. Y-axis coils 63b may be provided on both sides of the electron beam path 65 along the Y-axis. The X-axis current source 64a may provide a current to the X-axis coils 63a to generate a magnetic field in the X-axis coils 63a. The Y-axis current source 64b may provide a current to the Y-axis coils 63b to generate a magnetic field in the Y-axis coils 63b. The magnetic field may pass through the electron beam path 65 . The electron beam passing through the electron beam path 65 may be deflected by the magnetic field generated in the X-axis coils 63a and the Y-axis coils 63b. A current provided by the X-axis current source 64a may be defined as an X current, and a current provided by the Y-axis current source 64b may be defined as a Y current.

A limiting electrode 70 may be provided above the deflector 60 . In other words, the limiting electrode 70 may be provided between the deflector 60 and the anode 40 . A positive voltage may be applied to the limiting electrode 70 . The limiting electrode 70 may include a limiting opening 71 . The diameter of the limiting opening 71 may be 1 μm to 2000 μm. The shortest distance between the electron beam generator 10 and the limiting electrode 70 may be 0.1 mm to 200 mm. The diameter of the limiting opening 71 may be appropriately determined according to the shortest distance between the electron beam generator 10 and the limiting electrode 70 . For example, when the shortest distance between the electron beam generator 10 and the limiting electrode 70 is 200 mm, the diameter of the limiting opening 71 may be 2000 μm. As another example, when the shortest distance between the electron beam generator 10 and the limiting electrode 70 is 0.1 mm, the diameter of the limiting opening 71 may be 1 μm. The limiting electrode 70 may include a lower surface 72 facing the cathode 11 . An ammeter 73 may be connected to the limiting electrode 70 . The limiting electrode 70 may include tungsten or molybdenum.

A second focusing electrode 80 may be provided on the limiting electrode 70 . In other words, the second focusing electrode 80 may be provided between the limiting electrode 70 and the anode 40 . A positive voltage may be applied to the second focusing electrode 80 . The second focusing electrode 80 may include a second focusing electrode opening 81 .

When explaining a method of driving the X-ray imaging apparatus, first to fourth electron beams 14a-14d may be emitted from the first to fourth nano-emitters 13a-13d (refer to FIG. 2B ) on the cathode 11 . .

The first to fourth electron beams 14a-14d emitted from the first to fourth nano-emitters 13a-13d are accelerated by the voltage difference between the anode 40 and the cathode 11 and the anode 40 ) can proceed in the same direction. The traveling paths of each of the first to fourth electron beams 14a-14d may be different from each other.

The first to fourth electron beams 14a - 14d may pass through the gate opening 21 of the gate electrode 20 .

The first to fourth electron beams 14a - 14d passing through the gate opening 21 may pass through the first focusing opening 31 of the first focusing electrode 30 . While passing through the first focusing opening 31 , the first to fourth electron beams 14a - 14d may be focused.

The first to fourth electron beams 14a - 14d passing through the first focusing opening 31 may pass through the electron beam path 65 defined by the deflector 60 . Passing through the electron beam path 65 , the first to fourth electron beams 14a - 14d may be deflected along the X and Y axes ( FIGS. 5A and 5B ). When the deflector 60 is an electrostatic deflector ( FIG. 5A ), the first to fourth electron beams 14a - 14d passing through the electron beam path 65 are deflected by the electric field generated in the electron beam path 65 . can When the deflector 60 is a magnetic field type deflector (FIG. 5B), the first to fourth electron beams 14a-14d passing through the electron beam path 65 may be deflected by the magnetic field passing through the electron beam path 65. there is. By controlling the deflector 60, the deflection of the first to fourth electron beams 14a-14d may be adjusted.

The limiting electrode 70 may limit the progress of the first to fourth electron beams 14a-14d. Only one of the first to fourth electron beams 14a - 14d that has passed through the electron beam path 65 may pass through the confinement opening 71 of the confinement electrode 70 . For example, the second electron beam 14b may pass through the confinement opening 71 . Although the second electron beam 14b is shown passing through the confinement opening 71 , one of the first, third and fourth electron beams 14a , 14c , 14d may pass through the confinement opening 71 . The confinement opening 71 may have a suitable size so that only one electron beam can pass therethrough. According to the deflection of the first to fourth electron beams 14a-14d by the deflector 60 , the electron beam passing through the restriction opening 71 may be determined. According to the deflection of the first to fourth electron beams 14a-14d by the deflector 60 , none of the first to fourth electron beams 14a-14d may pass through the limiting opening 71 .

When the second electron beam 14b passes through the limiting opening 71 , the first, third, and fourth electron beams 14a , 14c , and 14d may be irradiated onto the lower surface 72 of the limiting electrode 70 . there is. A current may flow in the limiting electrode 70 by the first, third, and fourth electron beams 14a, 14c, and 14d irradiated to the lower surface 72 of the limiting electrode 70 . The current flowing through the limiting electrode 70 may be measured by the ammeter 73 of the limiting electrode 70 .

The second electron beam 14b passing through the limiting opening 71 may pass through the second focusing opening 81 of the second focusing electrode 80 . While passing through the second focusing opening 81 , the second electron beam 14b may be focused. By controlling the second focusing electrode 80 , the focusing can be adjusted so that the focal spot of the second electron beam 14b is minimized on the surface of the anode 40 .

The second electron beam 14b passing through the second focusing opening 81 may be irradiated to the anode 40 . The second electron beam 14b may be irradiated to the anode 40 , and the X-rays 43 may be emitted from the anode 40 . The X-rays 43 may travel from the anode 40 toward the image acquisition unit 50 . The X-ray 43 may be irradiated to the subject SJ disposed between the anode 40 and the image acquisition unit 50 .

X-rays 43 may be irradiated to the image acquisition unit 50 . The image acquisition unit 50 may acquire an X-ray image of the subject SJ. Since an X-ray image is obtained by one X-ray 43 , the X-ray image of the subject SJ may be clear.

As the magnitude of the current of the second electron beam 14b passing through the limiting opening 71 increases, a clearer X-ray image may be obtained.

6 is an X-ray image obtained by the X-ray imaging apparatus of FIG. 4 .

Referring to FIG. 6 , it can be confirmed that the subject appears clearly in the X-ray image obtained by one X-ray.

7 is a diagram for explaining an intensity map of a current measured by a limiting electrode.

4, 5A, 5B and 7 , an intensity map of the current flowing through the limiting electrode 70 may be obtained using the ammeter 73 connected to the limiting electrode 70 . The current intensity map may be obtained based on an electrostatic deflector ( FIG. 5A ) or a magnetic field type deflector ( FIG. 5B ). In the following description, an example will be described with reference to the electrostatic deflector ( FIG. 5A ). A case based on the magnetic field type deflector (FIG. 5B) may also be similar to the description below.

The current intensity map may include a plurality of pixels. The magnitude of the X voltage of the deflector 60 may be displayed on the X-axis of the current intensity map, and the magnitude of the Y voltage of the deflector 60 may be displayed on the Y-axis of the current intensity map. Each pixel may have a magnitude of an X voltage and a magnitude of the Y voltage corresponding thereto. For example, the magnitude of the X voltage corresponding to the first pixel P1 is X1, and the magnitude of the Y voltage is Y1. As another example, the magnitude of the X voltage corresponding to the second pixel P2 is X2, and the magnitude of the Y voltage is Y2. In other words, when the magnitude of the X voltage of the deflector 60 is X1 and the magnitude of the Y voltage is Y1, the intensity of the current flowing through the limiting electrode 70 may appear in the first pixel P1 of the current intensity map. there is. When the magnitude of the X voltage of the deflector 60 is X2 and the magnitude of the Y voltage is Y2, the intensity of the current flowing through the limiting electrode 70 may appear in the second pixel P2 of the current intensity map. As described above, the current intensity map may indicate the intensity of the current flowing through the limiting electrode 70 according to the change in the magnitude of the X voltage and the change in the magnitude of the Y voltage of the deflector 60 .

In the current intensity map, as the intensity of the current flowing through the limiting electrode 70 increases, the brightness of each pixel may be brighter. Comparing the first pixel P1 and the second pixel P2, since the brightness of the first pixel P1 is brighter than the brightness of the second pixel P2, the X voltage of the deflector 60 is X2 When the X voltage of the deflector 60 is X1 and the Y voltage is Y1 than when the Y voltage is Y2, the strength of the current flowing through the limiting electrode 70 may be greater.

Obtaining the current intensity map includes changing the magnitude of the X voltage and the magnitude of the Y voltage of the deflector 60 within a specific range, and flowing through the limiting electrode 70 according to the magnitude of the X voltage and the Y voltage within the range. It may include measuring the intensity of the current and displaying the brightness of pixels of the current intensity map.

4 , when the first to fourth electron beams 14a-14d are emitted from the first to fourth nano-emitters 13a-13d, the first to fourth spots SP1-SP4 in the current intensity map ) and a peripheral area AR may be formed. Each of the first to fourth spots SP1 to SP4 and the peripheral area AR may be formed by collecting pixels having the same brightness. The first to fourth spots SP1 to SP4 may be relatively darker than the peripheral area AR. The second spot SP2 may be brighter than the first spot SP1, the third spot SP3 may be brighter than the second spot SP2, and the fourth spot SP4 may be brighter than the third spot SP3. can be bright

When the deflector 60 has the X voltage and the Y voltage corresponding to the pixels located in the first spot SP1, the electron beam having the largest current among the first to fourth electron beams 14a-14d is It can pass through the limiting opening 71 .

When the deflector 60 has the X voltage and the Y voltage corresponding to the pixels located in the second spot SP2, the magnitude of the current is the second largest among the first to fourth electron beams 14a-14d. The electron beam may pass through the confinement opening 71 .

When the deflector 60 has the X voltage and the Y voltage corresponding to the pixels located in the fourth spot SP4, the electron beam having the smallest current among the first to fourth electron beams 14a-14d is It can pass through the limiting opening 71 .

When the deflector 60 has the X voltage and the Y voltage corresponding to the pixels located in the peripheral area AR, neither the first to fourth electron beams 14a to 14d pass through the limiting opening 71 . can

When the deflector 60 is controlled so that the magnitudes of the X voltage and the Y voltage of the deflector 60 correspond to pixels in the first spot SP1 by checking the current intensity map, the first to fourth electron beams ( 14a-14d), the electron beam having the largest current may pass through the limiting opening 71 .

In the current intensity map, the first to fourth spots SP1 to SP4 may reflect the shape of the limiting opening 71 . In other words, when the limiting opening 71 is circular in plan view, the first to fourth spots SP1 to SP4 may be formed in a circular shape. The fourth spots SP1 - SP4 may be formed in a quadrangular shape.

8A to 8C are views for explaining a shape of an electron beam passing through a restriction opening.

4, 7 and 8A , according to the focusing of the first focusing electrode 30 , the electron beam 14 is focused such that the planar area is minimized at the same level as the lower surface 72 of the limiting electrode 70 . can be In other words, the focus may be formed at the same level as the lower surface 72 of the limiting electrode 70 . In this case, in the current intensity map of FIG. 7 , the first to fourth spots SP1 to SP4 may be formed relatively clearly. By controlling the first focusing electrode 30 , the focusing of the electron beam 14 may be adjusted so that the planar area of the electron beam 14 is minimized at the same level as the lower surface 72 of the limiting opening 71 . By checking the sharpness of the current intensity map, it can be confirmed whether the planar area of the electron beam 14 is minimized at the same level as the lower surface 72 of the limiting opening 71 .

Referring to FIGS. 4 and 8B , according to the focusing of the first focusing electrode 30 , the electron beam 14 may proceed in a diverging manner while passing through the limiting opening 71 of the limiting electrode 70 . In other words, as the electron beam 14 travels within the confinement opening 71, its planar area may gradually increase. The electron beam 14 may impinge on the upper sidewalls 74a of the confinement opening 71 . X-rays may be generated at the upper sidewalls 74a of the restriction opening 71 by the electron beam 14 . X-rays generated from the upper sidewalls 74a of the limiting opening 71 may travel toward the anode 40 . The X-rays may be irradiated to the subject SJ and the image acquisition unit 50 . Due to the X-rays, the sharpness of the X-ray image acquired by the image acquisition unit 50 may decrease.

4 and 8C , according to the focusing of the first focusing electrode 30 , the electron beam 14 may travel in a convergent manner while passing through the limiting opening 71 of the limiting electrode 70 . In other words, as the electron beam 14 travels within the confinement opening 71, its planar area may gradually decrease. The electron beam 14 may impinge on the lower surface 72 of the confinement opening 71 . X-rays may be generated from the lower surface 72 of the restriction opening 71 by the electron beam 14 . The X-rays may not travel in the direction of the anode 40 because they are limited by the limiting opening 71 .

9A and 9B are actual images of the current intensity map of the limiting electrode.

Referring to FIGS. 9A and 9B , in the current intensity map of FIG. 9A , it can be seen that spots where relatively dark pixels are gathered are formed to be distinguishable from other parts, and in FIG. 9B, spots are formed to be distinguishable from other parts. You can check that it is not. As shown in FIG. 8A , when the planar area of the electron beam is minimized at the same level as the lower surface of the limiting opening, a current intensity map as shown in FIG. 9A may be obtained. Unlike FIG. 8A, when the planar area of the electron beam is larger than the diameter of the restriction opening at the same level as the lower surface of the restriction opening, a current intensity map as shown in FIG. 9B may be obtained. The smaller the planar area of the electron beam at the same level as the lower surface of the limiting opening, the better the clarity of the current intensity map.

10 is a flowchart illustrating a method of driving an X-ray imaging apparatus according to embodiments of the present invention.

4 and 10 , the first to fourth electron beams 14a-14d may be emitted from the first to fourth nano-emitters 13a-13d by applying a voltage to the gate electrode 20 , , a voltage may be applied to the anode 40 to accelerate the first to fourth electron beams 14a to 14d ( S1 ).

The first to fourth electron beams 14a-14d may be focused by applying a voltage to the first focusing electrode 30 ( S2 ).

A current intensity map flowing through the limiting electrode 70 by the first to fourth electron beams 14a-14d may be obtained using the deflector 60 and the ammeter 73 ( S3 ).

It is determined whether the spots of the current intensity map are clear (S4), and when the spots of the current intensity map are not clearly obtained, the first to fourth electron beams 14a-14d are controlled by controlling the first focusing electrode 30. It is possible to adjust the focus (S5). Adjusting the focusing may include minimizing the planar area of the electron beam passing through the confinement opening 71 at the same level as the lower surface 72 of the confinement opening 71 . Controlling the focusing of the first to fourth electron beams 14a-14d, and again using the deflector 60 and the ammeter 73, the limiting electrode 70 by the first to fourth electron beams 14a-14d ) to obtain a current intensity map flowing in (S3). The above process can be repeated until the spots on the current intensity map become clear.

It is determined whether the spots of the current intensity map are clear (S4), and when the spots of the current intensity map are clearly obtained, the deflection of the first to fourth electron beams 14a-14d can be optimized using the current intensity map. There is (S6). The deflection optimization includes identifying the darkest spot in the current intensity map and adjusting the deflection of the first to fourth electron beams 14a-14d by controlling the deflector 60 to correspond to the darkest spot. may include When the deflector 60 is an electrostatic deflector (FIG. 5A), the magnitude of the voltage applied by the X-axis voltage source 62a and the Y-axis voltage source 62b can be optimized, and the deflector 60 is a magnetic field deflector. In the case of a group (FIG. 5B), the magnitude of the current provided by the X-axis current source 64a and the Y-axis current source 64b can be optimized. According to the deflection optimization, the electron beam having the largest current value among the first to fourth electron beams 14a-14d may pass through the restriction opening 71 .

By controlling the second focusing electrode 80, the focusing of the electron beam passing through the limiting opening 71 may be adjusted (S7). Accordingly, the focal spot of the electron beam passing through the limiting opening 71 can be focused so as to be minimized on the surface of the anode 40 .

11 is a view for explaining an X-ray imaging apparatus according to embodiments of the present invention. The same reference numerals are used for the same components described with reference to FIG. 4, and overlapping descriptions will be omitted.

Referring to FIG. 11 , a negative voltage may be applied to the cathode 11 , and the anode 40 may be grounded. Although the limiting electrode 70 is illustrated as being grounded, a negative voltage or a positive voltage may be applied thereto.

As mentioned above, although embodiments of the present invention have been described with reference to the accompanying drawings, those of ordinary skill in the art to which the present invention pertains can practice the present invention in other specific forms without changing its technical spirit or essential features. You will understand that there is Therefore, it should be understood that the embodiments described above are illustrative in all respects and not restrictive.

10: electron beam generator
20: gate electrode
30: first focusing electrode
40: anode
50: image acquisition unit
60: deflector
70: limiting electrode
80: second focusing electrode

Claims (10)

An electron beam emission step for generating electron beams from an electron beam generator, wherein the electron beam generator includes a first nano-emitter for generating a first electron beam and a second nano-emitter for generating a second electron beam;
a first electron beam focusing step of focusing each of the first and second electron beams using a first focusing electrode;
deflecting the focused first and second electron beams using a deflector;
an electron beam limiting step of restricting propagation of the first electron beam by using a limiting electrode including a limiting opening and passing the second electron beam through the limiting opening; and
Including an anode irradiation step of irradiating the first electron beam passing through the limiting opening to the anode,
The limiting of the electron beam further includes obtaining a current intensity map of the limiting electrode by measuring a current flowing through the limiting electrode.
delete The method of claim 1,
The first electron beam focusing step includes controlling the first focusing electrode so that a planar area of the second electron beam is minimized within the limiting opening using the current intensity map. The method of claim 1,
Using the current intensity map includes checking the sharpness of the current intensity map. The method of claim 1,
The first electron beam focusing step includes controlling the first focusing electrode to minimize a planar area of the electron beams at the same level as a lower surface of the limiting opening. The method of claim 1,
The deflecting step may include identifying a darkest spot in the current intensity map and controlling a voltage level of a voltage source of the deflector to correspond to the darkest spot. The method of claim 1,
and a second electron beam focusing step of focusing the second electron beam that has passed through the limiting opening. An electron beam emission step for generating electron beams from an electron beam generator, wherein the electron beam generator includes a first nano-emitter for generating a first electron beam and a second nano-emitter for generating a second electron beam;
a first electron beam focusing step of focusing each of the first and second electron beams using a first focusing electrode;
deflecting the focused first and second electron beams using a deflector;
an electron beam limiting step of restricting propagation of the first electron beam by using a limiting electrode including a limiting opening and passing the second electron beam through the limiting opening; and
Including an anode irradiation step of irradiating the first electron beam passing through the limiting opening to the anode,
The method of driving an X-ray imaging apparatus further comprising measuring a current flowing through the limiting electrode. The method of claim 1,
Each of the first nano-emitter and the second nano-emitter includes carbon nanotubes. The method of claim 1,
The first nano-emitter and the second nano-emitter are attached to the upper surface of the cathode,
An angle formed between the first nano-emitter and the upper surface of the cathode is different from an angle formed between the second nano-emitter and the upper surface of the cathode.

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