JP5111788B2 - X-ray generation power supply - Google Patents

Description

  The present invention relates to an X-ray generation power supply device, and more particularly to an X-ray generation power supply device for generating X-rays from an X-ray tube provided with a deflection electrode for deflecting an X-ray beam.

  In recent X-ray tubes, a rotating anode type in which an umbrella-shaped anode is rotated in order to greatly increase the allowable load is generally used, and thermoelectrons emitted from a heated filament are focused by a focusing body, The focused thermoelectrons are accelerated by a high voltage applied between the anode and the cathode (filament) and collide with the target of the rotating anode to generate X-rays.

The X-ray tube that generates X-rays in this way has the following problems and requirements, and various countermeasures have been proposed.
(1) Movement of the focal position due to thermal expansion of the anode The energy conversion efficiency of the X-ray tube is very low, and most of the energy is converted to heat. Since the focal point on the anode target moves in the tube axis direction of the X-ray tube, the focal point, which is the X-ray generation source on the anode target, moves to the cathode side.

The focal point should be in the central part of the X-ray emission window of the envelope that originally accommodates the anode and cathode, but as described above, the focal point moves to the cathode side with respect to the central part of the X-ray emission window. Therefore, the focal shift is as large as 500 μm or more before and after the load application.
As a result, the X-ray dose distribution fluctuates and greatly affects the X-ray image.
This effect becomes a particularly serious problem when used with a small slice width in an X-ray CT apparatus.

(2) Support for 3 or more filaments
There is a dual-focus X-ray tube with two large and small focal points.
The small focus is used for high resolution, and the large focus is used for high output.In order to further improve the image quality by subdividing the focus size and using it for various applications, the focus size is increased. Increasing the number of filaments is required to increase the choice of focus size.
However, increasing the number of filaments to 3 or more is not practical in terms of structure.

(3) Fast switching between X-ray exposure and stop
The X-ray exposure / stop switching time is preferably as short as possible to reduce exposure and to clarify the image when performing X-ray fluoroscopy with pulsed X-rays. In the control by ON / OFF of the high voltage applied between the anode and the cathode while the filament is heated by using a high voltage device, the microsecond is extremely high due to the presence of circuit impedance such as a high voltage transformer or a high voltage cable. Switching in a short order is practically impossible.

(4) Improving the spatial resolution of X-ray CT images The X-ray detector irradiates the subject with X-rays from a single focal position, and the X-ray detector detects the X-rays that have passed through the subject. Can't hope.
That is, the spatial resolution of the above method is determined by the interval between the X-ray detection elements of the X-ray detector, and in order to improve the spatial resolution, the interval between the X-ray detection elements must be reduced, This is determined by the size of the X-ray detection element and is physically limited.

  Therefore, for example, the two focal positions are alternately moved at high speed at the positions of the X-ray tube rotating around the subject and the discrete X-ray tube positions per rotation of the X-ray detector (referred to as “view”). By detecting projection data corresponding to each moved focal position, the projection data detected by the X-ray detector can be doubled.

  Thus, by increasing the projection data by shifting the X-ray beam by half within the same view, it becomes equivalent to the case where the interval between the X-ray detection elements is halved. It is possible to improve the spatial resolution of CT images by reconstructing projection data. That is, it is possible to improve the spatial resolution by detecting projection data and reconstructing an image every 1/2 pitch of an actual X-ray detection element.

In the above problems, there is a technique disclosed in Patent Documents 1 and 2 for the above (1). This is because the focusing electrode of the filament is provided with a focusing electrode, and the voltage applied to the focusing electrode is varied to control the electric field distribution between the filament and the anode target, thereby deflecting the electron trajectory generated from the filament. It is a solution.
That is, for (1) above, the voltage applied to the focusing electrode is controlled so that the focal point, which is the X-ray generation source due to the thermal expansion of the anode member of the rotating anode X-ray tube, is always at a fixed position (patent) References 1 and 2).

  For the above (2) and (3), by providing a plurality of electrically insulated focusing electrode elements and controlling the voltage applied to each of these focusing electrode elements to be the same or different from each other. Adjust the electric field distribution formed by the focusing electrode, move the target X-ray focal point from the expected position, return the moved X-ray focal point to the expected position, and further apply the voltage applied to each focusing electrode element. By setting it lower / higher than the reference voltage, the focus size can be changed smaller / larger than the reference size, which can increase the X-ray exposure and stop switching speed and the focus size (Patent Document 2). ).

The above (4) is disclosed in Patent Document 3, in which the electric field distribution formed by the focusing electrode is controlled, and the X-ray focal point is alternately moved at a high speed for imaging.
Japanese Patent Laid-Open No. 10-116579 JP 2004-95196 A JP 2000-287960 A

The filament of the X-ray tube has a very large potential difference with respect to the ground of -70 kV or -140 kV.
Therefore, the voltage applied to the electron deflection focusing electrode adjacent to the filament also has a large potential difference with respect to the ground, so how to cope with this large potential difference is as described in (1) to (4) above. It becomes a big subject in putting to practical use.
However, none of the above Patent Documents 1, 2, and 3 mentions the problem of the large potential difference and the countermeasures against it.
That is, no consideration is given to means for generating a voltage to be applied to the focusing electrode in order to cope with a large potential difference with respect to the ground.
For this reason, if the power supply means applied to the focusing electrode is not clear, the above-mentioned various problems cannot be realized using an X-ray tube provided with the focusing electrode.

In the X-ray CT apparatus, since the thickness of the examination site of the subject, that is, the X-ray absorption rate differs depending on the angle of X-ray irradiation, X-ray irradiation required depending on the examination site and the examination angle Since the amounts are also different, the exposure X-ray dose can be reduced by appropriately controlling the X-ray irradiation amount.
Therefore, in order not to irradiate the subject with excessive X-rays, the current flowing between the anode and cathode of the X-ray tube during scanning (hereinafter referred to as tube current) is controlled according to the body thickness of the subject. To do.

However, recent X-ray CT devices have been increased in speed, and the tube current needs to be controlled at a high speed. However, since this tube current control is performed by heating the filament, it is controlled by the presence of the thermal inertia of the filament. There is a limit to speeding up the response speed, and even if the speed of the X-ray CT apparatus is increased, it is difficult to control the tube current for reducing exposure corresponding thereto.
For such tube current control corresponding to high-speed CT, it is also conceivable to use an X-ray tube equipped with the focusing electrode and control the voltage applied to the focusing electrode of the X-ray tube to reduce exposure.

  Accordingly, an object of the present invention has been made in view of the above problems, and a power supply device that applies to the focusing electrode of an X-ray tube having a focusing electrode without complicating a circuit configuration, and an output of the power supply The voltage can be made variable so that X-ray focal position variation correction, focus size diversification, X-ray exposure and stopping speed can be increased, aggressive focus movement and tube current control speed can be increased. An object of the present invention is to provide a power generator for generating lines.

  In order to achieve the above object, the X-ray generation power supply device of the present invention is configured as follows. That is, it has a filament that emits thermoelectrons, a cathode portion that has at least two insulated focusing electrodes that deflect the beam direction of the thermoelectrons from the filament, and an anode target that is disposed to face the cathode portion A voltage is applied between the focusing electrode and a high voltage generating means for applying a high DC voltage between the anode part and the cathode part, a filament heating means for heating the filament, and an X-ray tube having an anode part. An X-ray generating power supply device comprising an electron beam deflection voltage generating means for deflecting the direction of the thermoelectron beam, the X-ray high voltage apparatus comprising the high voltage generating means and the filament heating means The X-ray generating power supply apparatus is configured including the electron beam deflection voltage generating means.

  An X-ray generation power supply device configured to include the electron beam deflection voltage generating means in the X-ray high voltage device includes one end of an output end of the filament heating means and one end of an output end of the electron beam deflection voltage generating means. First connecting means for connecting the negative voltage of the high voltage generating means, a terminal for applying the output voltage of the filament heating means to the filament, and the output voltage of the electron beam deflection voltage generating means between the focusing electrodes The filament heating means and the electron having a first high voltage connector provided on the X-ray tube side having a terminal to be applied, an output terminal of the filament heating means and an output terminal of the electron beam deflection voltage generating means A second high-voltage connector provided on the beam deflection voltage generating means side, and a second high-voltage connector for connecting the first high-voltage connector and the second high-voltage connector. And a connection means, using said first connecting means and the high voltage cable to the second connection means.

The output voltage of the electron beam deflection voltage generating means is an AC voltage, and this AC voltage is applied between the focusing electrodes to deflect the beam direction of the thermoelectrons generated from the filament.
The electron beam deflection voltage generating means includes a first DC power supply, a first DC / AC conversion means for converting the DC voltage of the DC power supply into a high-frequency AC voltage, and the conversion means converts the DC voltage into a high-frequency AC voltage. A first transformer that insulates and boosts the generated voltage, and further, the first DC power source and the first DC / AC converter are the DC voltage of the first DC power source and / or the The output AC voltage of the first DC / AC converter is configured to be variable.

  Further, the secondary winding of the first transformer is a secondary winding with a neutral point, and the neutral point is connected to one end of the output end of the filament heating means and the negative potential of the high voltage generating means. It may be configured.

  The electron beam deflection voltage generating means includes a first electron beam deflection voltage generating means for generating a first DC voltage, and a second electron beam deflection voltage generating means for generating a second DC voltage. The first and second electron beam deflection voltage generating means have means for varying the respective output DC voltage, and switching control means for controlling generation and stop of the first and second DC voltages, and The minus potential of each of the first DC voltage and the second DC voltage is connected to one end of the output end of the filament heating means and the minus potential of the high voltage generating means, and the first electrons are controlled by the switching control means. The beam deflection voltage generating means and the second electron beam deflection voltage generating means are alternately controlled to switch the output voltage of the electron beam deflection voltage generating means to an AC voltage.

  Further, the second DC power supply, the second DC / AC conversion means for converting the DC voltage of the DC power supply into a high-frequency AC voltage, and the voltage converted into the high-frequency AC voltage by the conversion means are insulated. A voltage adjusting means for adjusting the potential for controlling the neutral point potential of the first transformer secondary winding configured by the second transformer to be boosted is provided, and the second DC power source and the second DC / The AC conversion means is configured to be able to vary the DC voltage of the second DC power supply and / or the output AC voltage of the second DC / AC conversion means.

  And a filament heating means for heating at least two filaments, and an electron beam deflection voltage generating means for applying to the focusing electrode for deflecting the beam direction of the thermoelectrons generated from these filaments. It should be compatible with X-ray tubes having the above filaments.

  Further, it is possible to operate as a triode X-ray tube having a grid function by providing means for giving a potential difference between the focusing electrode and the filament.

  According to the present invention, the first connecting means for connecting one end of the output end of the filament heating means and one end of the output end of the electron beam deflection voltage generating means to the negative potential of the high voltage generating means, and the filament heating means A first high-voltage connector on the X-ray tube side having a terminal for applying an output voltage to the filament and a terminal for applying the output voltage of the electron beam deflection voltage generating means between the focusing electrodes; and an output terminal of the filament heating means And a second high voltage connector on the X-ray generation power supply device side having an output terminal of the electron beam deflection voltage generating means, and a first high voltage connector for connecting the first high voltage connector and the second high voltage connector. An X-ray generating power supply device comprising an electron beam deflection voltage generating means in the X-ray high voltage device using a high voltage cable for the first connecting means and the second connecting means. Therefore, without complicating the circuit configuration, the power supply device applied to the focusing electrode of the X-ray tube including the focusing electrode and the output voltage of the power source can be configured to be variable to correct the variation in the X-ray focal position. It is possible to provide an X-ray generation power supply device capable of diversifying the focus size, accelerating X-ray exposure and stopping, aggressively moving the focus, and accelerating the tube current control.

Preferred embodiments of the X-ray generating power supply device of the present invention will be described below in detail with reference to the accompanying drawings.
First, before describing an embodiment of an X-ray generation power supply device, an X-ray tube including a focusing electrode to which the X-ray generation power supply device of the present invention is applied will be described.

FIG. 5 is a schematic structural diagram of the anode and cathode of an X-ray tube provided with a focusing electrode to which the X-ray generation power supply device of the present invention is applied.
This X-ray tube 6 accommodates an anode 61 and a cathode 62 in a glass bulb maintained at a high vacuum, and the anode 61 has a collision surface (target) formed by bonding tungsten and molybdenum, for example, An umbrella-shaped rotating anode having a large heat capacity on the back surface is provided with a rotating mechanism (not shown) so as to be rotatable at high speed.

The cathode unit 62 includes a coiled filament 62a that emits thermoelectrons and a focusing body for focusing the thermoelectrons from the filament 62a. The focusing body includes a focusing electrode 62b and a focusing electrode 62c. I have.
The focusing electrode 62b and the focusing electrode 62c are electrically insulated from the filament 62a, and the heat applied from the filament 62a to the anode target by changing the voltage applied to the focusing electrode 62b and the focusing electrode 62c. The direction of electrons can be deflected.
That is, the focusing electrode 62b, the focusing electrode 62c, a voltage applying means (electron beam deflection voltage generating circuit) to be applied to these electrodes, and a means for controlling the voltage are used to determine the electric field distribution between the filament met and the anode target. Electron trajectory deflecting means is configured to deflect the trajectory of the thermoelectrons emitted from the filament 62a under control.

The filament 62a is provided with filament terminals 81 and 82 for applying a voltage for heating the filament, and the focusing electrodes 62b and 62c deflect the beam direction of thermoelectrons generated from the filament 62a. Focusing electrode terminals 83 and 84 for applying a voltage for the purpose are provided.
Then, an AC voltage is applied between the high voltage generating circuit (high voltage generating means) for applying a DC high voltage to the filament 62a which is the anode 61 and the cathode 62, and the terminals 81 and 82 of the filament 62a. An electron beam deflection voltage for applying a voltage between the filament heating circuit (filament heating means) for heating the filament 62a and the focusing electrode terminals 83 and 84 for deflecting the beam direction of the thermoelectrons generated from the filament 62a And a generation circuit (electron beam deflection voltage generation means).

  The X-ray tube configured in this manner heats the filament to a predetermined temperature by the filament heating circuit, and applies a high DC voltage between the anode 61 and the cathode 62 from the high voltage generation circuit in this state. As a result, thermoelectrons are generated from the filament, and X-rays are generated when the thermoelectrons collide with the anode target.

To change the collision position of the thermal electrons that collide with the anode target, an arbitrary voltage from the electron beam deflection voltage generation circuit is applied between the focusing electrodes 62b and 62c, and the electric field strength distribution between the filament met and the anode target is determined. This is accomplished by deflecting the trajectory of the thermoelectrons emitted from the filament 62a.
The high voltage generation circuit and the filament heating circuit are a voltage applied between the anode and cathode of the X-ray tube (hereinafter referred to as tube voltage) and a current flowing between the anode and cathode (hereinafter referred to as tube current). These are also called X-ray high voltage devices.
That is, the X-ray high-voltage device has a high-voltage generation function and a function of controlling X-rays generated from the X-ray tube, and the present invention is further released from the filament 62a to the X-ray high-voltage device. Specific means for adding the function of deflecting the orbit of thermionic electrons will be presented.

In the X-ray tube shown in FIG. 5, the electric field distribution formed by the focusing electrode is adjusted by controlling the voltage distribution applied to the focusing electrode, and the X-ray focal point position on the target is moved from the target position. The moved X-ray focal point can be returned to the target position, and the size of the X-ray focal point can be changed.
For example, by controlling the potential of the focusing electrode 62b to be lower than the potential of the focusing electrode 62c, the electron flow can be deflected to the opposite side of the focusing electrode 62b, and the potential of the focusing electrode 62b is made to be lower than the potential of the focusing electrode 62c. By controlling it higher, the electron flow can be deflected toward the focusing electrode 62b.
Furthermore, the electron current can be deflected in an arbitrary direction by arbitrarily varying the voltages applied to the focusing electrodes 62b and 62c.
Also, by setting the voltage applied to the focusing electrodes 62b and 62c to be lower / higher than the reference voltage, the focal spot size can be changed to be smaller / larger than the reference size.

<< First Embodiment >>
FIG. 1 is a block configuration diagram showing an X-ray generation power supply device according to a first embodiment of the present invention.
This X-ray generation power supply device includes a high voltage generation circuit 10 that generates a DC high voltage (tube voltage) applied to the anode portion 61 and the cathode portion 62 of the X-ray tube 6, and a filament of the X-ray tube 6. Filament heating circuit 20 for controlling current (tube current) flowing between anode 61 and cathode 62 by heating 62a, and focusing electrode for deflecting the beam direction of the thermoelectrons generated from filament 62a Electron beam deflection voltage generation circuit 30 for applying a voltage between terminals 83 and 84, output terminals 91 and 92 of filament heating circuit 20, and terminal groups of output terminals 93 and 94 of electron beam deflection voltage generation circuit 30 It is comprised with nine.

  The high voltage generation circuit 10 includes a DC power source 11, an inverter circuit 21 that converts the DC voltage of the DC power source 11 into an AC voltage having a high frequency (hereinafter abbreviated as high frequency), and a high frequency AC voltage in the inverter circuit 21. A high-voltage transformer 31 that boosts the voltage converted into a high voltage, a high-voltage rectifier 41 that is connected to the secondary side of the high-voltage transformer 31 and rectifies the boosted AC voltage, and is connected to the high-voltage rectifier 41. The first smoothing capacitor 51 for smoothing the output voltage, and the DC high voltage smoothed by the first smoothing capacitor 51 is converted into the anode terminal 61a and the cathode terminal (the terminal of the filament 62a) of the X-ray tube 6. ) Apply between 81.

  The filament heating circuit 20 includes a DC power source 12, an inverter circuit 22 that converts a DC voltage of the DC power source 12 into a high-frequency AC voltage, and a filament that insulates a voltage converted into a high-frequency AC voltage by the inverter circuit 22. The heating transformer 32 is configured, and the output AC voltage of the transformer 32 is applied between the filament terminals 81 and 82 to heat the filament 62a to a predetermined temperature.

The high voltage generation circuit 10 and the filament heating circuit 20 configured as described above are known inverter type X-ray high voltage devices, and the tube voltage of the X-ray tube 6 is the DC voltage of the DC power source 11 of the high voltage generation circuit 10 and Alternatively, the output AC voltage of the inverter circuit 21 is configured to be variable, and is controlled to a predetermined value by the tube voltage variable means.
The tube current of the X-ray tube 6 is configured so that the DC voltage of the DC power source 12 of the filament heating circuit 20 and / or the output AC voltage of the inverter circuit 22 can be varied, and is controlled to a predetermined value by the tube current varying means. To do.
In this way, the X-ray dose irradiated to the subject is controlled according to the imaging conditions by controlling the tube voltage and tube current of the X-ray tube.

The X-ray generation power supply device of the present invention is provided with focusing electrode terminals 83 and 84 for deflecting the beam direction of thermoelectrons generated from the filament 62a to the X-ray high voltage device for controlling the tube voltage and tube current. An electron beam deflection voltage generating circuit 30 for applying a voltage between the DC power source 13 (first DC power source) and the DC voltage of the DC power source 13 is added. Inverter circuit 23 (first DC / AC conversion means) for converting to a high-frequency AC voltage, and an electron beam deflection transformer 33 that insulates and boosts the voltage converted to a high-frequency AC voltage by the inverter circuit 23 ( First transformer), and the voltage of the secondary winding 331, which is the output AC voltage of the transformer 33, is applied between the focusing electrode terminals 83 and 84, and the thermoelectrons from the filament 62a are applied. To deflect the direction.
Then, the DC voltage of the DC power supply 13 and / or the output AC voltage of the inverter circuit 23 can be varied, and the deflection direction of the thermoelectrons is controlled to be deflected to a target direction by the deflection voltage varying means.

In the circuit thus configured, the potential of the focusing electrode 62c is the same as that of the filament 62a, the potential of the focusing electrode 62b is a potential that changes between plus and minus with respect to the focusing electrode 62c, and the frequency thereof is an inverter circuit. This is the same frequency as the 23 operating frequency.
Therefore, if the focal position on the anode target 61 when the focusing electrodes 62b and 62c are both equal to the potential of the filament 62a is the reference position, the focal position on the anode target 61 is focused on the potential of the focusing electrode 62b. When it is positive with respect to the electrode 62c, it moves to the right side of FIG. 5, and when it is negative, it moves to the left side of FIG. Thus, the beam direction of the thermoelectrons generated from the filament 62a can be deflected by varying the voltage applied to the focusing electrodes 62b and 62c.

As described above, by variably controlling the voltage applied to the focusing electrode of the filament, the focal position on the anode target 61 is moved from the reference position to the predetermined position and returned from the moved predetermined position to the reference position. be able to.
Therefore, when this technique is applied to an X-ray CT apparatus, by controlling the voltage applied to the focusing electrode so that the movement of the focal position due to thermal expansion of the anode target is always the reference position, artifacts due to focal movement can be reduced. Occurrence can be prevented and a high-quality tomographic image can be obtained.

In addition, by controlling the voltage applied to the focusing electrode to move the focal position alternately between the reference position and the predetermined position at a high speed, the X-ray beam in the same view is shifted by half, and the actual 1 / This is equivalent to detecting projection data with a two-pitch X-ray detector, thereby increasing the projection data.
Therefore, the spatial resolution of the CT image can be improved by reconstructing a large number of projection data detected in this way.

  In addition, the response of the tube current control can be improved compared to the conventional tube current control performed only by controlling the filament current, and the tube current can be controlled at a higher speed than the conventional one, so that the high speed rotation can be achieved. The tube current can be controlled accordingly, and a high-speed X-ray CT system with low exposure can be realized.

Further, by applying a potential difference between the focusing electrode and the filament, the focusing electrode can be used as a triode X-ray tube serving as a grid.
Specifically, the tube current can be cut off by applying a negative potential to the focusing electrode with respect to the filament potential.
In other words, the X-ray can be opened and closed by controlling the voltage applied to the focusing electrode, and such a function can be achieved by controlling the current during fluoroscopy of the fluoroscopic imaging apparatus in a pulsed manner. By using X-ray pulse fluoroscopy to sharpen the image, the wave tail at the fall of the tube voltage due to the stray capacitance existing in the high-voltage cable can be eliminated, improving the image quality of the fluoroscopic image and improving the X-ray tube This contributes to a reduction in the heat capacity of the tube and a reduction in exposure to soft X-rays at the rise and fall of the tube voltage.

  Furthermore, since the focal point shift technique can obtain a large number of focal point sizes without increasing filaments, the focal point size can be increased without increasing the size of the X-ray tube, and an appropriate focal point size can be selected according to various applications. It is possible to obtain a high-quality image according to the diagnostic application.

  In the X-ray generation power supply device of the present invention configured as described above, as shown in FIG. 1, the focusing electrode 62c of the X-ray tube 6 is connected to the filament 62a, and the X-ray high voltage device ( 10 and 20) and the cathode 62 of the X-ray tube 6 are connected by a high voltage cable 7, and in addition to a conductor for applying the output voltage of the filament heating circuit 20 to the filament 62a, The configuration includes a voltage applying conductor for applying the output voltage of the electron beam deflection voltage generating circuit 30 to the focusing electrodes 62b and 62c.

  Thus, the terminals 81 and 82 for applying the output voltage of the filament heating circuit 20 to the filament 62a and the terminals 83 and 84 for applying the output voltage of the electron beam deflection voltage generating circuit 30 to the focusing electrodes 62b and 62c are provided. A high voltage connector 8 having a filament and focusing electrode high voltage connector 8 (first high voltage connector), output terminals 91 and 92 of the filament heating circuit 20 and output terminals 93 and 94 of the electron beam deflection voltage generation circuit 30 9 (second high voltage connector) is used to connect the high voltage cable 7 and the X-ray high voltage device and the high voltage cable 7 and the X-ray tube 6 (first connection means, second Connection means).

  Further, since it is insulated from the primary side of the transformer 33 by the electron beam deflection transformer 33, it can be connected to a filament potential (for example, -70 kV to -140 kV), and the high voltage cable 7 as described above. In addition to the power supply conductor for heating the filament, the voltage supply conductor for the focusing electrode is included, so that the X-ray high voltage device (10, 20) and the cathode side of the X-ray tube 6 are connected to each other as in the conventional case. It is possible to connect with a cable of a book, and although the means for applying a voltage to the focusing electrode is added, the cable wiring is not complicated.

  By configuring in this way, for example, the potential of the voltage application terminals 83 and 84 of the focusing electrode is several kV (for example 2 kV) with respect to the voltage application terminals 81 and 82 for heating the filament of the high voltage connector 8, Although sufficient consideration should be given to the insulation between the voltage application terminals 81 and 82 and the voltage application terminals 83 and 84, a voltage sufficiently lower than the potential of the filament 62a itself (for example, −70 kV or −140 kV). As a result, insulation mounting can be simplified.

<< Second Embodiment >>
FIG. 2 is a block diagram showing an X-ray generation power supply device according to the second embodiment of the present invention.
The X-ray generation power supply device of FIG. 2 is provided with a secondary winding 331 ′ with a neutral point instead of the electron beam deflection transformer 33 of the electron beam deflection voltage generation circuit 30 in the first embodiment. The electron beam deflection transformer 33 'is provided to constitute an electron beam deflection voltage generating circuit 30', and the neutral point of the secondary winding 331 'of the electron beam deflection transformer 33' is used as the filament 62a. Connected.

In the electron beam deflection voltage generating circuit 30 ′ configured as described above, the potentials of the focusing electrodes 62b and 62c are alternating potentials that change alternately between plus and minus with the potential of the filament 62a as the center.
Therefore, the output voltage of the electron beam deflection voltage generation circuit 30 in the first embodiment (voltage of the secondary winding 331) and the output voltage of the electron beam deflection voltage generation circuit 30 ′ in the second embodiment (secondary winding). 331 ′ voltage), the voltage between the focusing electrodes 62b and 62c is the same in the first and second embodiments, but the voltage between the filament 62a and the focusing electrodes 62b and 62c is The second embodiment is half that of the first embodiment, and the insulation design is facilitated.
That is, since the insulation distance can be reduced while obtaining the same deflection effect, the mounting can be simplified.

<< Third Embodiment >>
FIG. 3 is a block diagram showing an X-ray generation power supply device according to the third embodiment of the present invention.
The X-ray generation power supply device of FIG. 3 includes two power supply circuits 100b (first electron beam deflection voltage generation means) and 100c (second electron beam deflection voltage generation means) 30 and 30 ′ shown in FIGS. The electron beam deflection voltage generating circuit 100) is composed of an electron beam deflection voltage generating circuit 100, the output voltages of the power supply circuits 100b and 100c are set as DC voltages, and the negative potentials of these DC voltages are connected to each other. The positive terminal of the output DC voltage of the power supply circuits 100b and 100c is connected to the focusing electrodes 62b and 62c, respectively, connected to the filament terminal 81.

  The power supply circuit 100b of the electron beam deflection voltage generation circuit 100 includes a DC power supply 100b1, an inverter circuit 100b2 that converts the DC voltage of the DC power supply 100b1 into a high-frequency AC voltage, and a high-frequency AC voltage in the inverter circuit 100b2. An electron beam deflecting transformer 100b3 that insulates and boosts the voltage converted into a voltage, a first rectifier 100b4 that converts the output AC voltage of the electron beam deflecting transformer 100b3 into a DC voltage, and rectification by the rectifier 100b4 And a second smoothing capacitor 100b5 for smoothing the DC voltage generated. Similarly, the power supply circuit 100c includes a DC power supply 100c1 and an inverter circuit 100c2 for converting the DC voltage of the DC power supply 100c1 into a high-frequency AC voltage. An electron beam deflection transformer 100c3 that insulates and boosts the voltage converted into a high-frequency AC voltage by the inverter circuit 100c2, and an output AC voltage of the electron beam deflection transformer 100c3 A second rectifier 100c4 for converting the voltage into a DC voltage, and a third smoothing capacitor 100c5 for smoothing the DC voltage rectified by the rectifier 100c4, and the output DC voltage (second smoothing voltage) of the power supply circuit 100b. The negative potential of the capacitor 100b5) and the negative potential of the output DC voltage of the power supply circuit 100c (the voltage of the third smoothing capacitor 100c5) are connected, and this connection point is connected to the output terminal 91 of the filament heating circuit 20. Connected to the filament 62a (terminal 81), the positive potential (terminal 94) of the output DC voltage of the power supply circuit 100b is connected to the terminal 84 of the focusing electrode 62b, and the positive potential (terminal of the output DC voltage of the power supply circuit 100c) 93) is connected to the terminal 83 of the focusing electrode 62c.

The output voltage of the electron beam deflection voltage generation circuit 100 composed of the power supply circuits 100b and 100c is configured so that the DC voltage of the DC power supplies 100b1 and 100c1 and / or the output AC voltage of the inverter circuits 100b2 and 100c2 can be varied. By these deflection voltage varying means, the deflection direction of the thermoelectrons is controlled to be deflected to a target direction.
The power supply circuit 100b is a circuit for increasing the potential of the focusing electrode 62b with respect to the filament 62a, and the power supply circuit 100c is a circuit for increasing the potential of the focusing electrode 62c with respect to the filament 62a.

  With this configuration, the inverter circuit is intermittently operated to apply a pulse voltage between the focusing electrodes 62b and 62c, and the application timing of the pulse voltage is alternately turned ON / OFF by the inverter circuits 100b2 and 100c2. By doing so, it is possible to alternately move the focal point between predetermined positions, thereby preventing the CT image artifacts due to the focal point movement and improving the spatial resolution of the CT image by increasing the projection data. .

  Further, the absolute value of the voltage applied to the focusing electrodes 62b and 62c can be changed independently by the variable means of the DC voltage of the DC power supplies 100b1 and 100c1 and / or the output AC voltage of the inverter circuits 100b2 and 100c2. For example, the pulse voltage applied to the focusing electrode 62b is increased, the pulse voltage applied to the focusing electrode 62c is decreased, and the center position of the deflection of the electron beam is moved to the right side of FIG. The electron beam can be deflected.

Further, according to the third embodiment, for example, a constant voltage is applied to 62a instead of a pulse voltage, and control is performed so that no voltage is applied to 62c, thereby fixing the electron beam at the right position in FIG. And can be deflected.
That is, in order to obtain the two functions of improving the resolution of the captured image and correcting the focal position, the electron beam is deflected alternately around the point while controlling the center position of the deflection of the electron beam in FIG. It is possible to generate a voltage for realizing the above.

  The transformers 103b3 and 103c3 can be downsized by increasing the inverter operating frequency of the inverter circuits 100b2 and 100c2.

<< Fourth Embodiment >>
FIG. 4 is a block diagram showing an X-ray generation power supply device according to the fourth embodiment of the present invention.
The X-ray generation power supply device of FIG. 4 is the midpoint of the secondary winding 331 ′ of the electron beam deflection transformer 33 ′ for the electron beam deflection voltage generation circuit 30 ′ in the second embodiment shown in FIG. Is added with a voltage generating circuit 200 (potential adjusting voltage generating means).

The voltage generation circuit 200 includes a DC power supply 111 (second DC power supply), an inverter circuit 211 (second DC / AC conversion means) that converts a DC voltage of the DC power supply 111 into a high-frequency AC voltage, Insulating transformer 311 (second transformer) that insulates the voltage converted into high-frequency AC voltage by inverter circuit 211, and third rectifier 411 that converts the output AC voltage of this insulating transformer 311 to DC voltage; The fourth smoothing capacitor 511 that smoothes the DC voltage rectified by the rectifier 411, and the positive potential of the fourth smoothing capacitor 511 is connected to the positive output terminal (X-ray tube 6 The negative potential of the fourth smoothing capacitor 511 is connected to the neutral point of the secondary winding 331 ′ of the electron beam deflection transformer 33 ′ for the electron beam deflection voltage generation circuit 30 ′. .
Further, the DC voltage of the DC power source 111 of the voltage generation circuit 200 and / or the output AC voltage of the inverter circuit 211 can be made variable, and the output voltage of the voltage generation circuit 200, that is, the electric beam deflection voltage, can be changed by this voltage variable means. The neutral point potential of the secondary winding 331 ′ of the electron beam deflection transformer 33 ′ for the generating circuit 30 ′ is controlled to an arbitrary potential.

  The X-ray generation power supply device configured in this way is a high-voltage component of the voltage generation circuit 200 provided for controlling the neutral point potential of the secondary winding 331 ′ of the electron beam deflection transformer 33 ′ ( The third rectifier 411 and the fourth smoothing capacitor 511) are high-voltage components (first rectifier 100b4, second smoothing capacitor 100b5, and the like) of the electron beam deflection voltage generation circuit 100 in the third embodiment (FIG. 3). The second rectifier 100c4 and the third smoothing capacitor 100c5) are half the size and expensive high-voltage components, and the same effect as in the third embodiment can be obtained. The voltage generation circuit can be made small and economical.

<< Fifth Embodiment >>
The first to fourth embodiments are examples in which the X-ray generating power supply device of the present invention is applied to an X-ray tube having a single filament. The present invention can also be applied to an X-ray tube including two types of filaments for large focus, as in the above embodiments.
FIG. 6 is a block diagram showing an X-ray generation power supply device according to a fifth embodiment in which the present invention is applied to an X-ray generation power supply device according to the first embodiment applied to an X-ray tube having two types of filaments. It is.

  In FIG. 6, an X-ray tube 6 ′ (anode portion 61 ′, anode terminal 61a ′) having two filaments, a first filament 62a1 (for example, for a small focal point) and a second filament 62a2 (for example, for a large focal point). The focusing electrode of the cathode portion 62 ′) is a first focusing electrode 62b and a second focusing electrode 62c provided outside each of the two filaments, and a third focusing electrode provided between the two filaments. The first focusing electrode 62b and the second focusing electrode 62c are connected to have the same potential, and an electron beam deflection voltage is applied between the connection point and the third focusing electrode 62d. Apply.

  The X-ray generation power supply device of FIG. 6 for generating X-rays by applying a voltage to the X-ray tube having such a configuration is the same as the first filament 62a1 in the X-ray generation power supply device shown in FIG. In addition to the first filament heating circuit 20 for heating the second filament heating circuit 20 ′ for heating the second filament 62a2, the high voltage generation circuit 10 and the first filament heating circuit 20 ′ are provided. Since the filament heating circuit 20 and the electron beam deflection voltage generation circuit 30 are the same as those in FIG. 1, description of their configuration and operation is omitted.

  The second filament heating circuit 20 ′ has the same configuration as the first filament heating circuit 20, and includes a DC power supply 121 and an inverter circuit 221 that converts the DC voltage of the DC power supply 121 into a high-frequency AC voltage. This is composed of a filament heating transformer 321 that insulates the voltage converted into a high-frequency AC voltage by the inverter circuit 221, and the DC voltage of the DC power supply 121 and / or the output AC voltage of the inverter circuit 221 can be varied. The second filament 62a2 is heated and controlled by this variable means to control the tube current to a predetermined value.

  In the X-ray generation power supply device having the above configuration, one end of the first filament 62a1 and the second filament 62a2 are connected to each other (connection terminal 81), and the output AC voltage of the first filament heating circuit 20 is connected to the connection terminal. 81 is applied between the first filament 62a1 and the other terminal 82 of the first filament 62a1 to heat the first filament 62a1 to a predetermined temperature, and the output AC voltage of the second filament heating circuit 20 ′ is applied to the connection terminal 81. And the other terminal 85 of the second filament 62a2 to heat the second filament 62a2 to a predetermined temperature.

The output voltage of the electron beam deflection voltage generation circuit 30 is applied between the connection point (connection terminal 83) of the first focusing electrode 62b and the second focusing electrode 62c and the third focusing electrode 62d (terminal 84). Then, deflection control of the beam direction of the thermoelectrons generated from the first filament 62a1 or the second filament 62a2 is performed.
That is, when the beam direction of the thermoelectrons generated from the first filament 62a1 is deflected, the operation of the inverter circuit 221 of the second filament heating circuit 20 ′ is stopped and the second filament heating circuit 20 ′ When the output voltage is set to zero and the beam direction of the thermoelectrons generated from the second filament 62a2 is deflected, the operation of the inverter circuit 22 of the first filament heating circuit 20 is stopped and the first filament heating circuit is stopped. By setting the output voltage of 20 to zero, it becomes possible to deflect the directions of the thermoelectrons generated from the first filament 62a1 and the second filament 62a2 in the desired directions, respectively. The same effect as that of the embodiment can be obtained.

  In the X-ray generation power supply device of the fifth embodiment of the present invention configured as described above, as shown in FIG. 6, the first focusing electrode 62b and the second focusing electrode 62c of the X-ray tube 6 are The X-ray high-voltage device (10, 20, 20 ′) and the cathode 62 of the X-ray tube 6 are connected by a high-voltage cable 7 ′ and are connected to the filaments 62a1 and 62a2. In addition to the conductor for applying the output voltage of the filament heating circuits 20, 20 ′ to the first filament 62a1 and the second filament 62a2, the output voltage of the electron beam deflection voltage generation circuit 30 is the first focusing The electrode 62b, the second focusing electrode 62c, and the third focusing electrode 62d are configured to include a voltage applying conductor.

  In this way, the output voltages of the terminals 81, 82 and 85 for applying the output voltage of the filament heating circuits 20 and 20 ′ to the filaments 62a1 and 62a2 and the output voltage of the electron beam deflection voltage generating circuit 30 are applied to the focusing electrodes 62b, 62c and 62d. A high voltage connector 8 ′ having terminals 83, 84, an output terminal 91, 92 a, 92 b of the filament heating circuit 20, 20 ′ and an output terminal 93, 94 of the electron beam deflection voltage generation circuit 30. The high voltage cable 7 ′ and the X-ray high voltage device and the high voltage cable 7 ′ and the X-ray tube 6 ′ are connected using a voltage connector 9 ′.

  Further, since it is insulated from the primary side of the transformer 33 by the electron beam deflection transformer 33, it can be connected to a filament potential (for example, -70 kV to -140 kV), and the high voltage cable 7 as described above. 'Includes the power supply conductor for the focusing electrode in addition to the power supply conductor for heating the filament, so that the X-ray high-voltage device (10, 20, 20') and the X-ray tube 6 It is possible to connect the cathode side with a single cable, and the wiring of the cable is not complicated in spite of the addition of means for applying a voltage to the focusing electrode.

  With this configuration, for example, the potential of the voltage application terminals 83 and 84 of the focusing electrode is several kV (for example, 2 kV, for example) with respect to the voltage application terminals 81, 82 and 85 for heating the filament of the high voltage connector 8 ′. Therefore, the insulation between the voltage application terminals 81, 82, 85 and the voltage application terminals 83, 84 should be sufficiently considered, but the potential of the filaments 62a1, 62a2 itself (for example, −70 kV or −140 kV) Since the voltage is sufficiently small as compared with the above, insulation mounting can be simplified.

Although the present invention has been described with reference to the exemplary embodiments, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the gist of the present invention.
For example, the second embodiment of FIG. 2, the third embodiment of FIG. 3, and the fourth embodiment of FIG. 4 can be applied to an X-ray tube having a plurality of filaments and a focusing electrode.

  In the first to fifth embodiments, the DC power supplies 11, 12, 13, 100c1, 100b1, 111, 121 are configured to be provided for the respective voltage generation circuits, but these DC power supplies are shared. The output voltage of this circuit may be appropriately adjusted by each voltage varying means and output. By configuring the X-ray generation power supply device in this way, the size of the device can be reduced.

1 is a block configuration diagram showing an X-ray generation power supply device according to a first embodiment of the present invention. FIG. 5 is a block configuration diagram showing an X-ray generation power supply device according to a second embodiment of the present invention. FIG. 5 is a block configuration diagram showing an X-ray generation power supply device according to a third embodiment of the present invention. FIG. 5 is a block configuration diagram showing an X-ray generation power supply device according to a third embodiment of the present invention. The figure which shows the outline | summary of the structure of the anode and cathode of an X-ray tube provided with the focusing electrode to which the power supply device for X-ray generation of this invention is applied. FIG. 10 is a block configuration diagram showing an X-ray generation power supply device according to a fifth embodiment of the present invention.

Explanation of symbols

  6 X-ray tube, 7 high-voltage cable, 8 high-voltage connector for filament and focusing electrode, 9 high-voltage connector on the power supply side for X-ray generation, 10 high-voltage generation circuit, 20 filament heating circuit, 30 electron beam deflection voltage generation Circuit, 32 Filament heating transformer, 33 Electron beam deflection transformer, 61 Anode, 61a Anode terminal, 62 Cathode, 62a Filament, 62b, 62c Focusing electrode, 81, 82 Filament terminal, 83, 84 Focusing electrode terminal 91,92 Filament heating circuit output terminal, 93,94 Electron beam deflection voltage generation circuit output terminal

Claims (4)

An X-ray tube having a filament that emits thermoelectrons, a cathode portion having at least two focusing electrodes insulated from the filament, and an anode portion having an anode target disposed opposite to the cathode portion; High voltage generating means for applying a high direct current voltage between the anode part and the cathode part, filament heating means for heating the filament, and electrons for applying a voltage between the focusing electrodes to deflect the beam direction of thermoelectrons An X-ray generating power supply device comprising a beam deflection voltage generating means,
The electron beam deflection voltage generating means includes a first DC power supply, a first DC / AC conversion means for converting a DC voltage of the first DC power supply into an AC voltage, and the first DC / AC conversion means. A first transformer that boosts the voltage converted into an AC voltage at
The secondary winding of the first transformer is a secondary winding with a neutral point, and the neutral point is connected to one end of the output end of the filament heating means and the negative potential of the high voltage generating means A power supply device for generating X-rays. 2. The X-ray generating power supply device according to claim 1 , further comprising a voltage adjusting voltage generating means for controlling the potential of the neutral point. The potential adjusting voltage generating means includes: a second DC power supply; a second DC / AC converting means for converting a DC voltage of the second DC power supply into an AC voltage; and the second DC / AC converting means. Insulating transformer that insulates the voltage converted to AC voltage in, a rectifier that converts the output AC voltage of the insulating transformer into DC voltage, and a smoothing capacitor that smoothes the DC voltage rectified by the rectifier,
The positive potential of the smoothing capacitor is changed to the positive potential of the high voltage generating means.
3. The X-ray generation power supply device according to claim 2, wherein a negative potential of the smoothing capacitor is connected to the neutral point . The electronic output voltage of the beam deflection voltage generating means is an AC voltage, X-rays generation power source apparatus according to any one of claims 1 to 3 formed by applying the AC voltage between the focusing electrode.

Images