KR20200037763A - X-ray imaging device and driving method thereof - Google Patents

Abstract

The present invention relates to an X-ray imaging device capable of obtaining a clear image, and a driving method thereof. More specifically, the X-ray imaging device comprises: an electron beam generation unit including a plurality of nano emitters and a plurality of cathode; a first focusing electrode focusing electron beam emitted from the electron beam generation unit; a deflector deflecting the electron beam focused at the first focusing electrode; a limiting electrode limiting progress of the electron beam deflected by the deflector; and an anode emitting X-ray since the electron beam is irradiated. The limiting electrode includes a limiting aperture through which the electron beam may pass.

Description

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

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

The point electron source means an electron source where the flow of electrons starts at one point. In other words, a 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 electro-optical system, and thus has the advantage of making the probe beam relatively easy. . If the diameter of the electron beam is small, it can be very useful in various applications. For example, the resolution of an electron microscope such as SEM and TEM can be improved, and the focal spot of the X-ray can be reduced, thereby improving the resolution of the X-ray image.

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 is an electron beam generator comprising a plurality of nano-emitters and a cathode; A first focusing electrode 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 limiting the progress of the electron beam deflected by the deflector; And an anode that emits X-rays by irradiating the electron beam, and the limiting electrode provides an X-ray imaging apparatus including 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 X-ray image emitted from the anode may further include an image acquisition unit to acquire an X-ray image.

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 that applies 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 that provides current to the coils.

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

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

The present invention is an electron beam emission step of emitting a plurality of electron beams in the electron beam generator; An electron beam limiting step of limiting the progress of 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 provides a driving method of the X-ray imaging apparatus including a limiting opening through which the electron beams can pass.

The electron beam limiting step may include passing one electron beam of the electron beams emitted from the electron beam generator through the restriction opening.

The electron beam limiting step may include focusing electron beams emitted from the electron beam generation unit using a first focusing electrode.

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

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

Focusing 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 the 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 at 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 the magnitude of the voltage of the voltage source of the deflector.

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

The anode irradiation step may include focusing the one electron beam using a second focusing electrode.

The X-ray imaging apparatus according to the present invention includes a deflector and a limiting opening, so that one of the electron beams generated from a plurality of nano-emitters having the largest current magnitude can be irradiated to the anode and obtain a clear image. You can.

1A and 1B are diagrams for describing characteristics of an electron beam generated in a nano emitter.
2A is a diagram illustrating an X-ray imaging apparatus according to a comparative example of the present invention.
2B is an enlarged view of region A of FIG. 2A.
3 is an X-ray image obtained by the X-ray imaging apparatus according to 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 describing embodiments of the deflector.
6 is an X-ray image obtained by the X-ray imaging apparatus according to FIG. 4.
7 is a view for explaining the intensity map of the current measured at the limiting electrode.
8A to 8C are views for explaining the shape of the electron beam passing through the 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 be clarified with reference to embodiments described below in detail together 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 the present embodiments allow the disclosure of the present invention to be complete, and the general knowledge in the technical field to which the present invention pertains. It is provided to fully inform the holder of the scope of the invention, and the invention is only defined by the scope of the claims. The same reference numerals throughout the specification refer to the same components.

The terminology used herein is for describing the embodiments and is not intended to limit the present invention. In this specification, the singular form also includes the plural form unless otherwise specified in the phrase. As used herein, 'comprises' and / or 'comprising' refers to the components, steps, operations and / or devices mentioned above are the presence of one or more other components, steps, operations and / or devices. Or do not exclude additions.

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

1A and 1B are diagrams for describing characteristics of an electron beam generated in 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 are irradiated to the anode fluorescent film 41, so that the first to fourth electron beam fluorescent points 42a-42d can be formed on the anode fluorescent film 41. have. The characteristics of the first to fourth electron beams 14a-14d may be determined by observing the first to fourth electron beam fluorescence points 42a to 42d. Each of the first to fourth electron beam fluorescent points 42a-42d may be formed to correspond to the focal spot of each of the first to fourth electron beams 14a-14d. The focal spot may refer to 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.

The larger the voltage difference between the anode fluorescent film 41 and the cathode 11, the smaller the diameter of each of the first to fourth electron beam fluorescent points 42a-42d. 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 decreases. Can lose. The diameter of each of the first to fourth electron beam fluorescence points 42a-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 fluorescence points 42a-42d may increase as the distance between the anode fluorescent film 41 and the cathode 11 increases.

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 region 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.

The first to fourth nano emitters 13a-13d may be provided on the cathode 11. The number of nano emitters 13a-13d is illustrated as four, but may not be limited thereto. The cathode 11 can be grounded. The first to fourth nano emitters 13a-13d may be attached on 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 spaced apart from each other in a plane. 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 (CNT). The lengths of each of the first to fourth nano emitters 13a-13d may be different. The angle formed by the first to fourth nano emitters 13a-13d with the upper surface of the cathode 11 may be different. In other words, the degree of inclination of each of the first to fourth nano emitters 13a-13d may be different.

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

The 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.

The 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 position of the focusing electrode 30 may not be limited to this. 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. As an example, the anode target may include tungsten or molybdenum. The anode electrode may include a material having high electrical conductivity. As an 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 using X-rays emitted from the anode 40.

When explaining the driving method of the X-ray imaging apparatus, a positive voltage is applied to the gate electrode 20, and a voltage difference may occur between the gate electrode 20 and the cathode 11. By the voltage difference between the gate electrode 20 and the cathode 11, each of the first to fourth electron beams 14a-14d is to be emitted from each of the first to fourth nano emitters 13a-13a. You can. The first to fourth electron beams 14a-14d may be emitted at the ends of each of the first to fourth nano emitters 13a-13d. Among the first to fourth nano emitters 13a-13d, the length of the first nano emitter 13a may be the longest, and the length of the fourth nano emitter 13d may be the shortest. The longer the length of the nano emitters 13a-13d, the smaller the voltage difference between the gate electrode 20 and the cathode 11 from which the electron beams 14a-14d start to be emitted. In other words, the voltage difference between the gate electrode 20 and the cathode 11 at which the first electron beam 14a starts to be emitted from the first nano emitter 13a is the fourth electron beam from the fourth nano emitter 13d. It may be smaller than the voltage difference between the gate electrode 20 and the cathode 11 where 14d starts to be emitted. The smaller the diameter of the nano emitters 13a-13d, the smaller the planar area of the emitted electron beams 14a-14d.

A positive voltage is 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 are accelerated by the voltage difference between the anode 40 and the cathode 11 to proceed in the direction of the anode 40. have. The traveling paths of each of the first to fourth electron beams 14a-14d may be different. In other words, the paths through 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. Proceeding 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 for the first to fourth electron beams 14a-14d to pass through.

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 for the first to fourth electron beams 14a-14d to pass through. 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, focusing can be adjusted so that the focal spot of the first to fourth electron beams 14a-14d becomes 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 a different position irradiated to the anode 40. In other words, on the surface of the anode 40, the 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-14d may be irradiated to the anode 40, and the first to fourth X-rays 43a-43d may be emitted from the anode 40. Each of the first to fourth X-rays 43a-43d may have a different location emitted from the anode 40. In other words, on the surface of the anode 40, the emission points of the first to fourth X-rays 43a-43d may be spaced apart from each other.

The first to fourth X-rays 43a-43d may travel in the direction of the image acquisition unit 50 from the anode 40. As the emission points of the first to fourth X-rays 43a-43d are spaced apart from each other, while progressing in the direction of the image acquisition unit 50, each of the first to fourth X-rays 43a-43d progresses to each other 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-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-43d may be irradiated to the image acquisition unit 50. The X-ray image of the subject SJ may be acquired by the image acquisition unit 50. The X-ray images obtained by the first to fourth X-rays 43a-43d where the emission points are 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 overlap with each other.

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

Referring to FIG. 3, it can be confirmed that an object is not clearly displayed in an X-ray image obtained by a plurality of X-rays.

4 is a diagram for describing an X-ray imaging apparatus according to embodiments of the present invention, and FIGS. 5A and 5B are diagrams for illustrating embodiments of the deflector. The same reference numerals are used for the same components described with reference to FIGS. 2A and 2B, and duplicate 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, and an image acquisition unit 50, The deflector 60 may include 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 to this. The deflector 60 may be positioned between the first focusing electrode 30 and the gate electrode 20, or may be positioned between the gate electrode 20 and the cathode 11 (see 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. The electron beam path 65 may be defined by the X-axis electrodes 61a and the Y-axis electrodes 61b. X-axis electrodes 61a may be provided on both sides of the electron beam path 65 along the X-axis. Y-axis electrodes 61b may be provided on both sides of the electron beam path 65 along the Y-axis. The voltage difference between the X-axis electrodes 61a may be generated by the X-axis voltage source 62a applying a voltage to 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. The voltage difference between the Y-axis electrodes 61b may be generated 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. The voltage applied by the X-axis voltage source 62a may be defined as the X voltage, and the voltage applied by the Y-axis voltage source 62b may be defined as the Y voltage.

In another embodiment, the deflector 60 may be a magnetic field deflector (see FIG. 5B). The deflector 60 may include X-axis coils 63a, Y-axis coils 63b, X-axis current source 64a, and Y-axis current source 64b. The electron beam path 65 may be defined by X-axis coils 63a and 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. A magnetic field may be generated in the X-axis coils 63a by providing an electric current to the X-axis coils 63a. The Y-axis current source 64b provides 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 by the X-axis coils 63a and Y-axis coils 63b. The current provided by the X-axis current source 64a may be defined as X current, and the current provided by the Y-axis current source 64b may be defined as Y current.

A limiting electrode 70 may be provided over 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. For 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.

The 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 describing the driving method of the X-ray imaging apparatus, the first to fourth electron beams 14a-14d may be emitted from the first to fourth nano emitters 13a-13d (see 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 a voltage difference between the anode 40 and the cathode 11 to accelerate the anode 40. ) Direction. The traveling paths of each of the first to fourth electron beams 14a-14d may be different.

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. While 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 by the electric field generated in the electron beam path 65 will be deflected. You can. When the deflector 60 is a magnetic field 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. have. By controlling the deflector 60, the deflection of the first to fourth electron beams 14a-14d can 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 passing through the electron beam path 65 may pass through the limiting opening 71 of the limiting electrode 70. For example, the second electron beam 14b may pass through the limiting opening 71. Although the second electron beam 14b is shown passing through the limiting opening 71, one of the first, third and fourth electron beams 14a, 14c, 14d may pass through the limiting opening 71. The limiting opening 71 may have an appropriate size to allow only one electron beam to pass through. According to the deflection of the first to fourth electron beams 14a-14d by the deflector 60, an electron beam passing through the limiting opening 71 may be determined. Depending on the deflection of the first to fourth electron beams 14a-14d by the deflector 60, all of the first to fourth electron beams 14a-14d may not 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 on the lower surface 72 of the limiting electrode 70. have. Current may flow in the limiting electrode 70 by the first, third, and fourth electron beams 14a, 14c, and 14d irradiated on the lower surface 72 of the limiting electrode 70. The current flowing through the limiting electrode 70 can be measured in 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. The second electron beam 14b may be focused while passing through the second focusing opening 81. By controlling the second focusing electrode 80, the focusing can be adjusted so that the focal spot of the second electron beam 14b becomes minimum 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 is irradiated to the anode 40, and the X-ray 43 may be emitted from the anode 40. The X-ray 43 may travel from the anode 40 toward the image acquisition unit 50. The X-rays 43 may be irradiated to the subject SJ disposed between the anode 40 and the image acquisition unit 50.

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

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

6 is an X-ray image obtained by the X-ray imaging apparatus according to 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 view for explaining the intensity map of the current measured at the limiting electrode.

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

The current intensity map may consist of a plurality of pixels. The magnitude of the X voltage of the deflector 60 may be displayed on the X-axis of the current strength map, and the magnitude of the Y voltage of the deflector 60 may be displayed on the Y-axis of the current strength map. Each pixel may have a corresponding X voltage and Y voltage. 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. For 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. have. 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 of the magnitude of the X voltage and the change of the Y voltage of the deflector 60.

In the current intensity map, the greater the intensity of the current flowing through the limiting electrode 70, the brighter each pixel may be. When 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 Y voltage is Y2 and the X voltage of the deflector 60 is X1 and the Y voltage is Y1, the intensity of the current flowing through the limiting electrode 70 may be greater.

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

When the first to fourth electron beams 14a-14d are emitted from the first to fourth nano emitters 13a-13d as shown in FIG. 4, the first to fourth spots SP1-SP4 are added to the current intensity map. ) And the peripheral area AR may be formed. Each of the first to fourth spots SP1-SP4 and the peripheral area AR may be formed by collecting pixels having the same brightness. The first to fourth spots SP1-SP4 may be relatively dark compared to 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. It can be bright.

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

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

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

When the deflector 60 has X and Y voltages corresponding to pixels located in the peripheral area AR, all of the first to fourth electron beams 14a-14d do not pass through the limiting opening 71. You can.

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

In the current intensity map, the first to fourth spots SP1-SP4 may reflect the shape of the limiting opening 71. In other words, when the restricting opening 71 is planarly circular, the first to fourth spots SP1-SP4 may be formed in a circle, and when the restricting opening 71 is planarly square, the first to the fourth spots The fourth spots SP1-SP4 may be formed in a square shape.

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

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

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

4 and 8C, according to the focusing of the first focusing electrode 30, the electron beam 14 may proceed in a converging form 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 collide with the lower surface 72 of the limiting opening 71. X-rays may be generated in the lower surface 72 of the limiting opening 71 by the electron beam 14. The X-rays are limited by the limiting opening 71 and may not travel in the direction of the anode 40.

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

9A and 9B, in the current intensity map of FIG. 9A, it can be seen that spots in which relatively dark pixels are collected can be distinguished from other parts, and in FIG. 9B, spots are formed to be distinguishable from other parts. You can see that it has not been done As shown in FIG. 8A, when the planar area of the electron beam becomes minimum at the same level as the lower surface of the limiting opening, a current intensity map as in FIG. 9A can be obtained. Unlike FIG. 8A, when the planar area of the electron beam is larger than the diameter of the limiting opening at the same level as the lower surface of the limiting opening, a current intensity map as shown in FIG. 9B can 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 sharpness of the current intensity map may be.

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

4 and 10, 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-14d (S1).

A voltage may be applied to the first focusing electrode 30 to focus the first to fourth electron beams 14a-14d (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 obtained unclear, the first focusing electrode 30 is controlled to control the first to fourth electron beams 14a-14d. The focus can be adjusted (S5). Adjusting the focusing may include such that the electron beam passing through the limiting opening 71 has a minimum planar area at the same level as the lower surface 72 of the limiting opening 71. The limiting electrode 70 is controlled by the first to fourth electron beams 14a-14d by adjusting the focusing of the first to fourth electron beams 14a-14d and again using the deflector 60 and the ammeter 73. ), It is possible to obtain a current intensity map (S3). The above process can be repeated until the spots of the current intensity map become clear.

By determining whether the spots of the current intensity map are clear (S4), 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. Yes (S6). The deflection optimization is to identify the darkest spot in the current intensity map, and to control the deflector 60 so as to correspond to the darkest spot to adjust the deflection of the first to fourth electron beams 14a-14d. It can contain. 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 magnetic field deflection. In the case of origin (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 limiting 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, it is possible to focus so that the focal spot of the electron beam passing through the limiting opening 71 is 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 shown as being grounded, a negative voltage or a positive voltage may be applied.

The embodiments of the present invention have been described above with reference to the accompanying drawings, but those of ordinary skill in the art to which the present invention pertains can implement 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 (3)

An electron beam emitting step of generating electron beams from an electron beam generator, wherein the electron beam generator comprises a first nano-emitter generating a first electron beam and a second nano-emitter 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;
A deflection step of deflecting each of the focused first and second electron beams using a deflector;
An electron beam limiting step of limiting the progress 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
And an anode irradiation step of irradiating the anode with the first electron beam that has passed through the restriction opening. According to claim 1,
The electron beam limiting step further comprises obtaining a current intensity map of the limiting electrode by measuring a current flowing through the limiting electrode. According to claim 2,
And controlling the first focusing electrode such that the planar area of the second electron beam is minimized within the limited opening using the current intensity map.

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