An electron beam deflection control circuit and a CT detector

Abstract

The present invention provides an electron beam deflection control circuit and a CT detector. The electron beam deflection control circuit includes: a first branch, a second branch, a switching circuit, and a magnetic field generating device; the first branch is used to generate a first current; the second branch is used to generate a second current, and the first current and the second current are not equal; the switching circuit is used to control the first branch and the second branch to conduct alternately; the magnetic field generating device is used to generate a magnetic field for controlling the deflection of the electron beam. The first current is input from the first end of the magnetic field generating device and output from the second end, and the second current is input from the second end of the magnetic field generating device and output from the first end. By using the electron beam deflection control circuit provided by the invention, the current amplitude of the magnetic field deflection can be adjusted arbitrarily, and the asymmetric deflection of the electron beam can be realized.

Description

Technical Field

[0001] The present invention relates to the technical field of electron beam deflection, and particularly relates to an electron beam deflection control circuit and a CT detector. Background Art

[0002] The high-voltage generator is mainly used to provide a DC high-voltage power supply for externally connected devices, and is widely used in high-end medical products such as digital radiography (DR for short), computed tomography (CT for short), digital subtraction angiography (DSA for short), and scanning / transmission electron microscopes including electro-vacuum devices. The above high-end medical products and scanning / transmission electron microscopes all include vacuum devices for generating electron beams. The vacuum device usually uses an electrostatic field deflection system or a magnetic field deflection system to control the electron beam to achieve a deflection motion. The electrostatic field deflection system is small in volume, simple in structure, and fast in deflection speed, but has high insulation requirements and is generally used for deflection in the X and Y axes; the magnetic field deflection system is simple in structure, high in sensitivity, and does not need to consider insulation problems, and is generally used for deflection in the Z axis.

[0003] Regarding the deflection of the electron beam in the Z axis, the inventor found that for the traditional magnetic field deflection control circuit, only a symmetric magnetic field can be generated, so as to realize the symmetric deflection of the electron beam in the Z axis, but an asymmetric magnetic field cannot be generated, so as to realize the asymmetric deflection of the electron beam in the Z axis. Summary of the Invention

[0004] Therefore, the present invention aims to solve the technical problem that the traditional magnetic field deflection control circuit in the prior art can only realize the symmetric deflection of the electron beam in the Z axis, and thus provides an electron beam deflection control circuit and a CT detector.

[0005] According to a first aspect, an embodiment of the present invention provides an electron beam deflection control circuit, including: a first branch, a second branch, a switching circuit, and a magnetic field generating device;

[0006] The first branch is used to generate a first current;

[0007] The second branch is used to generate a second current, and the first current and the second current are not equal;

[0008] The switching circuit is used to control the first branch and the second branch to conduct alternately;

[0009] The magnetic field generating device is used to generate a magnetic field for controlling the deflection of the electron beam. The first current is input from the first end of the magnetic field generating device and output from the second end, and the second current is input from the second end of the magnetic field generating device and output from the first end.

[0010] Optionally, the magnitudes of the first current and the second current are both adjustable.

[0011] Optionally, the first branch includes a first DC / DC conversion circuit, and the second branch includes a second DC / DC conversion circuit.

[0012] Optionally, the first DC / DC conversion circuit or the second DC / DC conversion circuit includes:

[0013] A controllable switch, one end of which is connected to the positive pole of the power supply;

[0014] An inductor, one end of which is connected to the other end of the controllable switch, and the other end serves as the output end of the first DC / DC conversion circuit or the second DC / DC conversion circuit;

[0015] A diode, the cathode of which is connected to the other end of the controllable switch, and the anode is connected to the negative pole of the power supply.

[0016] Optionally, the switching circuit includes:

[0017] A first switch, one end of which is connected to the output end of the first DC / DC conversion circuit, and the other end is connected to the first end of the magnetic field generating device. The first switch is used to control the on / off of the first branch;

[0018] A second switch, one end of which is connected to the output end of the second DC / DC conversion circuit, and the other end is connected to the second end of the magnetic field generating device. The second switch is used to control the on / off of the second branch.

[0019] Optionally, the electron beam deflection control circuit further includes:

[0020] A third switch, which is connected in parallel with the first DC / DC conversion circuit and is used to form a loop with the first DC / DC conversion circuit when the magnetic field generating device is open;

[0021] A fourth switch, which is connected in parallel with the second DC / DC conversion circuit and is used to form a loop with the second DC / DC conversion circuit when the magnetic field generating device is open.

[0022] Optionally, the electron beam deflection control circuit further includes:

[0023] A bidirectional transient suppression diode, one end of which is connected to the first end of the magnetic field generating device and the other end is connected to the second end of the magnetic field generating device.

[0024] Optionally, the electron beam deflection control circuit further includes:

[0025] A capacitor, one end of which is connected to the first end of the magnetic field generating device and the other end of which is connected to the second end of the magnetic field generating device;

[0026] A smoothing capacitor, one end of which is connected to one end of the controllable switch and the other end of which is connected to the negative pole of the power supply.

[0027] Optionally, the electron beam deflection control circuit further includes:

[0028] A control module, which is respectively connected to the first branch, the second branch, and the switching circuit;

[0029] The control module respectively controls the first branch to generate the first current, controls the second branch to generate the second current, and is further used to control the switching circuit.

[0030] According to a second aspect, an embodiment of the present invention provides a CT detector, including the electron beam deflection control circuit described in any one of the above.

[0031] The technical solution of the present invention has the following advantages:

[0032] The present invention provides an electron beam deflection control circuit. By controlling the first branch and the second branch, the magnitudes of the first current and the second current are respectively changed, so that the magnitudes of the first current and the second current are not equal. Under the action of the switching circuit, an asymmetric deflection of the electron beam is realized. In the actual application process, by using the electron beam deflection control circuit in this embodiment, the current amplitude of the magnetic field deflection can be arbitrarily adjusted, the deflection angle of the electron beam can be changed, and the focus position of the electron beam can be quickly adjusted. At the same time, it is also possible to realize the rapid switching of the electron beam focus between two different target surfaces, realizing the flying focus or micro focus function. Further, the deflection range of the electron beam can be expanded, the detection width of the detector can be broadened, thereby improving the scanning efficiency and system imaging performance of medical products or industrial equipment. Description of the Drawings

[0033] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for use in the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0034] Figure 1 It is a structural diagram of a specific example of an electron beam deflection control circuit in Embodiment 1 of the present application;

[0035] Figure 2 It is a current waveform diagram of a specific example output when the magnitudes of the first current and the second current in Embodiment 1 of this application are equal;

[0036] Figure 3 It is a current waveform diagram of a specific example output when the first current and the second current in Embodiment 1 of this application are not equal;

[0037] Figure 4 It is a structural diagram of a specific example of the first DC / DC conversion circuit and the second DC / DC conversion circuit in Embodiment 1 of this application. Detailed implementation manners

[0038] Next, the technical solutions of the present invention will be clearly and completely described in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of them. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0039] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention. In addition, the terms "first", "second", "third" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance.

[0040] In the description of the present invention, it should be noted that unless otherwise clearly specified and limited, the terms "installed", "connected", "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, and can also be the communication inside two elements. It can be a wireless connection or a wired connection. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0041] In addition, the technical features involved in different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0042] Embodiment 1

[0043] This embodiment provides an electron beam deflection control circuit, which can be applied to medical products or industrial equipment that generate electron beams, etc., to achieve symmetric or asymmetric deflection of the electron beam. The electron beam deflection control circuit is as follows Figure 1 shown, including a first branch, a second branch, a switching circuit and a magnetic field generating device, specifically as follows.

[0044] The first branch is used to generate a first current i1;

[0045] The second branch is used to generate a second current i2, and the first current and the second current are not equal;

[0046] The switching circuit is used to control the first branch and the second branch to conduct alternately;

[0047] The magnetic field generating device 11 is used to generate a magnetic field for controlling the deflection of the electron beam. The first current enters from the first end 1 of the magnetic field generating device and exits from the second end 2. The second current enters from the second end 2 of the magnetic field generating device and exits from the first end 1.

[0048] The first branch and the second branch are independent of each other, and the currents in the first branch and the second branch can be independently adjusted. On the premise that the second branch is disconnected and the first branch is conducting, the first current generated by the first branch passes through the switching circuit and enters from the first end 1 of the magnetic field generating device, and exits from the second end 2 of the magnetic field generating device. Under the action of the first current, the magnetic field generating device generates a positive magnetic field or a reverse magnetic field. The magnetic field changes the emission direction of the electron beam, causing the electron beam to deflect positively or reversely in the Z-axis direction. Further, by changing the magnitude of the first current, the strength of the magnetic field can be changed, and thus the deflection angle of the electron beam can be changed.

[0049] Similarly, on the premise that the first branch is disconnected and the second branch is conducting, the second current generated by the second branch passes through the switching circuit and enters from the second end 2 of the magnetic field generating device, and exits from the first end 1 of the magnetic field generating device. Under the action of the second current, the magnetic field generating device generates a magnetic field in the opposite direction to that under the action of the first current. The magnetic field changes the emission direction of the electron beam, causing the electron beam to deflect in the opposite direction to that under the action of the first current in the Z-axis direction. Further, by changing the magnitude of the second current, the strength of the magnetic field can be changed, and thus the deflection angle of the electron beam can be changed.

[0050] When the first current and the second current flowing through the magnetic field generating device are equal, the electron beam generates symmetric deflection under the action of the magnetic field, as shown in Figure 2As shown, it is the current waveform output by the magnetic field generating device when the magnitudes of the first current and the second current are equal. When the magnitudes of the first current and the second current are changed separately and they are not equal when flowing through the magnetic field generating device, the electron beam generates asymmetric deflection according to the magnitudes of the first current or the second current, as Figure 3 As shown, it is the current waveform output by the magnetic field generating device when the magnitudes of the first current and the second current are not equal.

[0051] In this embodiment, by controlling the first branch and the second branch, the magnitudes of the first current and the second current are changed separately to make the magnitudes of the first current and the second current unequal, and under the action of the switching circuit, asymmetric deflection of the electron beam is achieved. In the actual application process, by using the electron beam deflection control circuit in this embodiment, the current amplitude of the magnetic field deflection can be adjusted arbitrarily, the deflection angle of the electron beam can be changed, and the focus position of the electron beam can be adjusted quickly. At the same time, rapid switching of the electron beam focus between two different target surfaces can be realized to achieve the function of flying focus or micro focus. Further, the deflection range of the electron beam can be expanded, the detection width of the detector can be broadened, thereby improving the scanning efficiency and system imaging performance of medical products or industrial equipment.

[0052] As an alternative embodiment, in the embodiment of the present invention, the magnitudes of the first current and the second current are both adjustable.

[0053] As an alternative embodiment, in the embodiment of the present invention, the first branch includes a first DC / DC conversion circuit 21, and the second branch includes a second DC / DC conversion circuit 22.

[0054] Specifically, both the first DC / DC conversion circuit and the second DC / DC conversion circuit can generate a constant current source with adjustable magnitude by adjusting the duty cycle.

[0055] As an alternative embodiment, in the embodiment of the present invention, the first DC / DC conversion circuit or the second DC / DC conversion circuit includes:

[0056] A controllable switch, one end of which is connected to the positive pole of the power supply;

[0057] An inductor, one end of which is connected to the other end of the controllable switch, and the other end is used as the output end of the first DC / DC conversion circuit or the second DC / DC conversion circuit;

[0058] A diode, the cathode of which is connected to the other end of the controllable switch, and the anode is connected to the negative pole of the power supply;

[0059] A smoothing capacitor, one end of which is connected to one end of the controllable switch, and the other end is connected to the negative pole of the power supply.

[0060] AsFigure 4 As shown, the first DC / DC conversion circuit 31 may include a controllable switch Q5, an inductor L1, a diode D1, and a first smoothing capacitor C1. The second DC / DC conversion circuit 32 may include a controllable switch Q6, an inductor L2, a diode D2, and a second smoothing capacitor C2. An adjustable first current is generated by the first DC / DC conversion circuit 31, and an adjustable second current is generated by the second DC / DC conversion circuit 32.

[0061] As an alternative embodiment, in the embodiments of the present invention, the switching circuit includes:

[0062] A first switch Q1, one end of which is connected to the first DC / DC conversion circuit and the other end of which is connected to the first end of the magnetic field generating device. The first switch is used to control the on / off of the first branch;

[0063] A second switch Q3, one end of which is connected to the second DC / DC conversion circuit and the other end of which is connected to the second end of the magnetic field generating device. The second switch is used to control the on / off of the second branch.

[0064] As Figure 1 shown, the first switch and the second switch may be MOSFET tubes or IGBT tubes. The drain of the first switch is connected to the output end of the first DC / DC conversion circuit, and the source is connected to the first end of the magnetic field generating device. The drain of the second switch is connected to the output end of the second DC / DC conversion circuit, and the source is connected to the second end of the magnetic field generating device.

[0065] When the first switch is turned on and the second switch is turned off, the first branch is turned on and the second branch is turned off. The first current in the first branch is output from the output end of the first DC / DC conversion circuit, flows through the first switch into the first end of the magnetic field generating device, and then is output from the second end of the magnetic field generating device. Under the action of the first current, the magnetic field generating device generates a positive magnetic field or a reverse magnetic field, and the magnetic field changes the electron beam emission direction, so that the electron beam generates a positive deflection or a reverse deflection in the Z-axis direction.

[0066] When the second switch is turned on and the first switch is turned off, the second branch is turned on and the first branch is turned off. The second current in the second branch is output from the output end of the second DC / DC conversion circuit, flows through the second switch into the second end of the magnetic field generating device, and then is output from the first end of the magnetic field generating device. Under the action of the second current, the magnetic field generating device generates a magnetic field in a direction opposite to that under the action of the first current.

[0067] As an alternative embodiment, in the embodiments of the present invention, the electron beam deflection control circuit further includes:

[0068] The third switch Q2, which is connected in parallel with the first DC / DC conversion circuit, is used to form a loop with the first DC / DC conversion circuit when the magnetic field generating device is open-circuited;

[0069] The fourth switch Q4, which is connected in parallel with the second DC / DC conversion circuit, is used to form a loop with the second DC / DC conversion circuit when the magnetic field generating device is open-circuited.

[0070] When the first switch is turned on, the second switch is turned off, the first branch is turned on, and the second branch is turned off, the third switch is turned off and the fourth switch is turned on. The first current in the first branch is output from the output terminal of the first DC / DC conversion circuit, flows through the first switch and into the first end of the magnetic field generating device. At this time, the second current in the second branch flows through the fourth switch and forms a loop with the second DC / DC conversion circuit.

[0071] Similarly, when the first switch is turned off, the second switch is turned on, the first branch is turned off, and the second branch is turned on, the third switch is turned on and the fourth switch is turned off. The second current in the second branch is output from the output terminal of the second DC / DC conversion circuit, flows through the second switch and into the second end of the magnetic field generating device. At this time, the first current in the first branch flows through the third switch and forms a loop with the first DC / DC conversion circuit.

[0072] Further, in this embodiment, when current flows through the magnetic field generating device, the magnetic field generating device malfunctions, resulting in an open circuit of the magnetic field generating device. If the magnetic field generating device, the first switch to the fourth switch are all open-circuited, voltage spikes will appear in the electron beam deflection control circuit, causing damage to the circuit.

[0073] Therefore, in order to prevent the components in the first branch from being damaged, the third switch connected in parallel in the first branch is turned on when the magnetic field generating device is open-circuited. The first current flows through the third switch and forms a loop with the first DC / DC conversion circuit, ensuring that the components in the first branch are not damaged. Similarly, in order to prevent the components in the second branch from being damaged, the fourth switch connected in parallel in the second branch is turned on when the magnetic field generating device is open-circuited. The second current flows through the fourth switch and forms a loop with the second DC / DC conversion circuit, ensuring that the components in the second branch are not damaged.

[0074] As an alternative embodiment, in the embodiment of the present invention, the electron beam deflection control circuit further includes:

[0075] The bidirectional transient voltage suppression diode D, one end of which is connected to the first end of the magnetic field generating device and the other end of which is connected to the second end of the magnetic field generating device, is used to suppress instantaneous high voltage and further ensure that the components in the electron beam deflection control circuit are not damaged by surge voltage.

[0076] As an alternative embodiment, in the embodiment of the present invention, the electron beam deflection control circuit further includes:

[0077] A capacitor C, one end of which is connected to the first end of the magnetic field generating device and the other end of which is connected to the second end of the magnetic field generating device, for absorbing the spike voltage generated by the circuit.

[0078] As an alternative embodiment, in the embodiment of the present invention, the electron beam deflection control circuit further includes:

[0079] A control module, which is respectively connected to the first branch, the second branch, and the switching circuit;

[0080] The control module respectively controls the first branch to generate the first current, controls the second branch to generate the second current, and is further used to control the switching circuit.

[0081] Control instructions can be sent to the control module through devices such as a server. The control module is used to respectively control the magnitude of the first current in the first branch and the magnitude of the second current in the second branch. The control module can also be used to control the switching circuit to control the rapid alternation of the first current and the second current flowing through the magnetic field generating device.

[0082] Embodiment 2

[0083] This embodiment provides a CT detector, which may include the electron beam deflection control circuit in Embodiment 1 above.

[0084] The CT detector in this embodiment adopts the electron beam deflection control circuit in Embodiment 1 above, and can arbitrarily adjust the current amplitude of the magnetic field deflection in the CT detector, realize the symmetric or asymmetric deflection of the X-ray, and can quickly adjust the position of the electron beam focus. At the same time, it can also enable the rapid transformation of the X-ray focus between two different target surfaces to realize the flying focus or micro focus function. Further, it can also expand the deflection range of the X-ray and broaden the detection width of the detector, thereby improving the scanning efficiency and system imaging performance of the CT detector.

[0085] For the specific description of the electron beam deflection control circuit, reference can be made to Method Embodiment 1 above, and details are not described herein again.

[0086] Obviously, the above embodiments are merely examples given for clear illustration and are not limitations on the implementation manners. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to enumerate all the implementation manners here. The obvious changes or modifications derived therefrom still fall within the protection scope of the present invention.

Claims

1. An electron beam deflection control circuit, characterized in that, Comprising: A first branch, a second branch, a switching circuit, and a magnetic field generating device; The first branch is used to generate a first current; The second branch is used to generate a second current, and the first current and the second current are not equal; the magnitudes of the first current and the second current are both adjustable; the first branch includes a first DC / DC conversion circuit, and the second branch includes a second DC / DC conversion circuit; The switching circuit is used to control the alternating conduction of the first branch and the second branch; The magnetic field generating device is used to generate a magnetic field for controlling the deflection of the electron beam. The first current is input from the first end of the magnetic field generating device and output from the second end, and the second current is input from the second end of the magnetic field generating device and output from the first end.

2. The electron beam deflection control circuit according to claim 1, characterized in that, The first DC / DC conversion circuit or the second DC / DC conversion circuit includes: A controllable switch, one end of which is connected to the positive pole of the power supply; An inductor, one end of which is connected to the other end of the controllable switch, and the other end serves as the output end of the first DC / DC conversion circuit or the second DC / DC conversion circuit; A diode, the cathode of which is connected to the other end of the controllable switch, and the anode is connected to the negative pole of the power supply; A smoothing capacitor, one end of which is connected to one end of the controllable switch, and the other end is connected to the negative pole of the power supply.

3. The electron beam deflection control circuit according to claim 1, characterized in that The switching circuit includes: A first switch, one end of which is connected to the output end of the first DC / DC conversion circuit, and the other end is connected to the first end of the magnetic field generating device. The first switch is used to control the on / off of the first branch; A second switch, one end of which is connected to the output end of the second DC / DC conversion circuit, and the other end is connected to the second end of the magnetic field generating device. The second switch is used to control the on / off of the second branch.

4. The electron beam deflection control circuit according to claim 1, characterized in that, Further comprising: A third switch, which is connected in parallel with the first DC / DC conversion circuit and is used to form a loop with the first DC / DC conversion circuit when the magnetic field generating device is open; A fourth switch, which is connected in parallel with the second DC / DC conversion circuit and is used to form a loop with the second DC / DC conversion circuit when the magnetic field generating device is open.

5. The electron beam deflection control circuit according to claim 1, characterized in that, Further comprising: A bidirectional transient suppression diode, one end of which is connected to the first end of the magnetic field generating device and the other end is connected to the second end of the magnetic field generating device.

6. The electron beam deflection control circuit according to claim 1, wherein Further comprising: A capacitor, one end of which is connected to the first end of the magnetic field generating device and the other end is connected to the second end of the magnetic field generating device.

7. The electron beam deflection control circuit according to claim 1, characterized in that, Further comprising: A control module, which is respectively connected to the first branch, the second branch, and the switching circuit; The control module respectively controls the first branch to generate the first current, controls the second branch to generate the second current, and is also used to control the switching circuit.

8. A CT detector, characterized in that, Comprising the electron beam deflection control circuit according to any one of claims 1-7.

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