JPH0568370A - DC high voltage generator and X-ray apparatus using the same - Google Patents

Abstract

(57) [Summary] [Purpose] The size and weight of the DC high-voltage generator are reduced, and at the same time the size and weight of the X-ray device main body are reduced, and at the same time, the amount of insulating oil in the oil tank is reduced to reduce costs. Lower. [Structure] In a structure in which the high voltage generating circuit is sealed with insulating oil in an oil tank consisting of the tank case body and the upper lid,
Two high-voltage sockets for positive and negative electrodes are mounted side by side on the upper lid, and a high-voltage transformer having one secondary winding is installed along these high-voltage sockets.
Install the circuit board on which the secondary winding is attached downward and the two sets of positive voltage and negative voltage doubler rectifier circuits are mounted symmetrically under the high voltage socket. In the direction corresponding to the positive and negative electrodes of the voltage doubler rectifier,
The input of the above two sets of voltage doubler rectifier circuits is connected to the secondary winding of the above high voltage transformer, and their positive and negative high voltage outputs are respectively connected to the above positive and negative high voltages The circuit and structure connected to the socket.

Description

Detailed Description of the Invention

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a DC high voltage generator suitable for supplying a high voltage to an X-ray tube, and an X-ray device equipped with the DC high voltage generator.

2. Description of the Related Art Recently, an X-ray power supply device using a high frequency inverter of several kHz to several tens of kHz has been put into practical use because of its advantages of high-speed response and low ripple. As described above, the miniaturization of the inverter part of the X-ray power supply device has been steadily progressed, but the miniaturization of the oil tank including the high-voltage transformer and the high-voltage rectification circuit, that is, the DC high-voltage generator is relatively small. Is late for The reason for this is that the high-voltage rectification method of the conventional DC high-voltage generator is the bridge rectification circuit of neutral point grounding shown in FIG. 51 in the figure
Is a high voltage transformer having two secondary windings 52 and 53 with a neutral point grounded, and 54, 55, 56 and 57 are bridge-connected high voltage diodes. In this method, since both electrodes of all the high voltage diodes 54 to 57 are at a high potential, it is necessary to use a high insulating material for wiring and mounting the high voltage diodes, and the high voltage transformer 51 has two high voltage diodes. It is difficult to reduce the size of the DC high voltage generator because the high voltage transformer becomes large because the windings 52 and 53 are required and the electrical insulation between the windings is also required. In addition, since the high-voltage part and the low-voltage part are intricately structured, the distance between the high-voltage part and the low-voltage part must be increased in order to ensure electrical insulation between them. This also contributed to the inability to reduce the size and weight of the DC high voltage generator.

SUMMARY OF THE INVENTION An object of the present invention is to realize a compact and lightweight X-ray device by reducing the size and weight of a DC high voltage generator for X-rays.

Therefore, according to the present invention, a high voltage transformer having one secondary winding and an AC high voltage from the secondary winding are provided in an oil tank composed of a case body and an upper lid. In a DC high-voltage generator in which a DC high-voltage generator for boosting and rectifying, a transformer for filament, and a divider for high-voltage detection are sealed with insulating oil, two high-voltage sockets for positive and negative electrodes are juxtaposed on the upper lid. Along with these high voltage sockets,
A circuit board for mounting the high-voltage transformer with its secondary winding facing downward and further mounting two sets of voltage-doubler rectifier circuits for positive and negative electrodes forming a DC high-voltage generating circuit Below the socket, the positive and negative electrodes of the high-voltage socket and the positive and negative electrodes of the above two sets of voltage-doubler rectifiers are arranged so as to correspond to each other and fixed substantially parallel to the upper lid,
Further, the positive and negative high voltage outputs of the two sets of the voltage doubler rectifier circuit of the positive electrode and the negative electrode are respectively connected to the positive and negative high voltage sockets.

BEST MODE FOR CARRYING OUT THE INVENTION The present invention mainly resides in the arrangement and structure of the members constituting the DC high voltage generator, but in order to facilitate understanding of the present invention, the circuit structure of the embodiment of the present invention shown in FIG. First, an example will be described. In the figure, reference numeral 1 is a grounded metal oil tank in which a high voltage transformer 2, a high voltage transformer 2, a positive voltage doubler voltage rectifier circuit 3 and a negative voltage doubler voltage rectifier circuit 4 are provided. , The filament transformer 5, the high-voltage detecting divider 26, etc. are sealed with insulating oil. 6 and 7 are high-frequency input terminals connected to the output of the high-frequency high-frequency inverter 8,
9 and 10 are filament inverter input terminals connected to the output of the filament inverter 11, 12 is a positive electrode high voltage socket for inserting and connecting the high voltage cable 14 connected to the anode A of the X-ray tube 13, 15 Is a negative electrode high voltage socket connected to the cathode K of the X-ray tube 13 for inserting and connecting the high voltage cable 16. The positive voltage doubler rectifier circuit 3 includes one double voltage capacitor 17, two sets of high voltage diode blocks 18 and 19 in which a plurality of diodes are connected in series to increase the breakdown voltage, and a plurality of capacitors to increase the breakdown voltage. It is composed of a filter capacitor block 20 in which are connected in series. Similarly, the negative voltage doubler rectifier circuit 4 includes one doubler voltage capacitor 21, two high voltage diode blocks 22 and 23, and a filter capacitor block 24. In this embodiment, the X-ray tube having a single filament is used, but the negative electrode high voltage socket 1 is used so as to be applicable to an X-ray tube having two filaments of a large focus filament and a small focus filament.
Reference numeral 5 is a three-pole type, and has a common terminal C, a large focal filament terminal L, and a small focal filament terminal S. Common terminal C
The negative output of the negative voltage doubler rectifier circuit 4 is connected to one end of the secondary winding 25 of the filament transformer 5, and the other ends of the secondary winding 25 are connected to the terminals S and L. Further, the positive electrode high voltage socket 12 also has three poles, and all terminals are short-circuited and connected to the positive output of the positive electrode voltage doubler rectifier circuit 3.
Reference numeral 26 is a divider for high voltage detection in which a plurality of resistors are connected in series in order to increase the breakdown voltage, which is connected between the positive output of the positive voltage doubler rectifier circuit 3 and the tube voltage detection terminal 27, and the tube voltage detection signal is a high voltage. Control voltage circuit 28 for stabilizing the output
Connected to. 29 is a terminal for detecting a high voltage output current,
That is, the tube current detection terminal detects the cathode current of the high-voltage diode block 22, and supplies the tube current detection signal to the tube current measuring circuit 30. This cathode current has a pulse shape, but is equal to the tube current when averaged. The tube current may be detected by detecting the anode current of the high voltage diode block 19. Reference numeral 31 is a signal return terminal for the tube voltage detection signal and the tube current detection signal, which is connected to the inner wall of the oil tank and, in some cases, the outer wall of the tank and grounded. Incidentally, 33 is a terminal of the DC high voltage generating circuit 32 corresponding to the signal return terminal 31, 34 is a tube current detection line,
35 is a tube current detection line 29 through a tube current detection line 34.
The terminals of the DC high-voltage generating circuit 32 connected to FIG. FIG. 2 shows an example of the structure of the high voltage transformer 2. A primary winding N1 is wound around one leg of a mouth-shaped iron core 40 that is a combination of UU-type or UI-type iron cores, and one secondary winding N is further provided on the leg.
2 is wound. f is a winding start terminal of the secondary winding N2 that is grounded, and g is a high-voltage side terminal thereof. Since the winding start terminal f of the secondary winding N2 is at the ground potential in this way,
It does not require a high breakdown voltage between 1 and N2.
000V is enough, and it is easy to manufacture a high voltage transformer.
In the present invention, the secondary winding voltage E of the high voltage transformer 2 is rectified to + 2E and -2E by the two voltage doubler rectifier circuits 3 and 4, and the voltage of 4E can be applied to the X-ray tube 13. Further, the ripple of the tube voltage applied to the anode A and the cathode K of the X-ray tube 13 is the same as the operating frequency of the high frequency inverter 8 as shown in FIG. 3, but they cancel each other because they are in opposite phases. As a result, the anode of the X-ray tube,
The ripple applied to the cathode is twice the operating frequency,
Moreover, there is an advantage of being small. As described above, according to the present invention, only one secondary winding of the high voltage transformer 2 is required, and the voltage doubler rectifying circuits 3 and 4 make the secondary winding voltage of the high voltage transformer 1 of the required X-ray tube voltage. Since / 4 is sufficient, 1/2 of the conventional secondary winding voltage is sufficient. Instead, the winding current capacity is 2
Although it doubles, the economical effect is large with only one secondary winding having a small number of turns. Further, although the number of high voltage diode blocks is increased to four, the withstand voltage may be half that of the conventional one.
Although the current capacity is doubled, it is technically difficult to raise the breakdown voltage of the high-voltage diode rather than increasing the current capacitance, and a low breakdown voltage is sufficient, so the economic effect is large. Especially in X-ray equipment, the operating time is often as short as a few seconds, and at the same time the idle period is considerably longer than that operating time, so overload is applied to the secondary windings of the high-voltage diode and the high-voltage transformer. It is also possible to call. In contrast to these advantages, in the present invention, the number of double voltage capacitors 17 and 21 is increased by two. However, the higher the operating frequency of the high frequency inverter 8, the smaller the capacity of the capacitor that can be used, and the breakdown voltage is 1 / the tube voltage. Since it only requires 4, it is not a big drawback. Further, as an embodiment of the present invention, by measuring the current flowing through the high-voltage diode block 22 on the ground side, the current due to the distributed capacitance of the high-voltage transformer 2 does not flow, so that accurate current detection is possible. In the practice of the present invention, when the ripple voltage of the X-ray tube voltage is not strictly required, the filter capacitors 20 and 24 may be removed and only the capacitance of the high voltage cables 14 and 16 may be used. In the experiment, in order to output a tube voltage of 100 kV and a tube current of 100 mA, a high frequency inverter of 20 kHz, a high voltage transformer that generates a secondary winding voltage of about 25 kV, a capacitor for doubling voltage of 1000 pF and 30 kV, and a withstand voltage of 60 kV. With four high voltage diode blocks and a high voltage cable of 2 m each, we were able to obtain fully practical output characteristics. The current can be detected by the anode current of the high voltage diode block 19. 4 (A) and 4 (B) are a top view and a cross-sectional perspective view of the oil tank according to the embodiment of the present invention with the upper lid removed. In the figure, the same symbols as in FIG. The tank case body 41 and the upper lid 42, which are filled with insulating oil, are made of rubber packing 4 that prevents oil leakage.
They are connected to each other with a bolt or the like (not shown) sandwiching 3. High-voltage sockets 12 and 15 for positive and negative electrodes having a structure defined by JIS or the like penetrate and are welded to the upper lid 42. The high voltage sockets 12 and 15 are structured to receive the high voltage cables 14 and 16 from the outside of the oil tank, and to connect the inside and outside of the oil tank with a high voltage metal fitting (not shown) near the bottom thereof. The high-voltage transformer 2 is attached from the high-voltage sockets 12 and 15 to the upper lid 42 with its secondary winding N2 facing downward at a substantially equal position and along the same positions. Further, four rectangular insulating columns 44, 45, 46, 47 extend downward from the upper lid 42, and a circuit board 48 for high voltage, for example, a printed circuit board, is suspended substantially horizontally from the lower ends of these columns. The circuit board 48 has a first
The high-voltage rectifier circuit surrounded by the one-dot chain line in the figure has a negative voltage doubler voltage rectifier circuit 4 on the right side and a positive electrode voltage doubler rectifier circuit 3 on the left side, which are arranged substantially symmetrically. Circuit board 48
Above, 17 and 21 are capacitors for voltage doubler, 20 and 24 are capacitor blocks for filters, and the arrangement of the diode blocks 18, 19, 22, 23 for high voltage is also shown. As can be seen from this arrangement, the circuit board 48
Has a high potential in the left-right direction, and the ground potential exists on a line located approximately in the middle between the positive voltage doubler voltage rectifier circuit 3 and the negative electrode voltage doubler rectifier circuit 4. Next, 49 is the ground point 33 on the circuit board 48.
It is a metal conductor that serves as a metal grounding pillar that connects the upper lid 42 to the upper lid 42, and the tube current detection line 34 rises from the circuit board 48 along the metal conductor 49. This metal conductor 49
Is placed approximately in the middle between the positive and negative high voltage sockets 12 and 15, and is the midpoint of the potential distribution between the electrodes of the socket. Therefore, the potential distribution is divided into two to stabilize, and discharge between the positive and negative electrodes is performed. Helps prevent. Further, the metal conductor 49 can also serve as a pillar of the tube current detection line 34. In FIG. 4 (A), the high-voltage transformer 2, positive and negative high-voltage sockets 12 and 15 are indicated by alternate long and short dash lines. Furthermore, 6
As shown in FIG. 5, reference numeral 1 denotes a printed circuit board having a plurality of divider resistors 26A connected in series which constitute a high voltage detecting divider 26, and which are attached along the longitudinal direction of the rectangular insulating columns 44 and 47. .. On the opposite side of the rectangular insulating struts 45 and 46, an insulating substrate 62 having the filament transformer 5 attached thereto as shown in FIG.
Mounted along the length of 5 and 46. The filament transformer 5 has a normal filament voltage of 3
Since the voltage is -10V, a primary winding (not shown) is wound around the ring core 63 for several tens of turns, and a high voltage insulated wire 64 is wound over it for several turns to form a secondary winding. The secondary winding is 1
1/2 of tube voltage, for example, 62.5kV to the next winding
Since the above withstand voltage is required, the wire itself has withstand voltage. All of these are arranged so that the high-voltage side is located downward, and sufficient electrical insulation between the oil tank wall and the wall is ensured. Since the drawing is complicated in FIG. 4A, the filament transformer 5 and the high voltage detecting divider 26 are omitted, and the terminals 6, 7, 9, 10 provided on the oil tank wall are omitted. , 27, 29, 31
Since it has a normal structure, its explanation is omitted. next,
According to the present invention, the rated output is 10 kW and the rated voltage is 125 kV.
In the embodiment in which the high voltage generator for X-ray is manufactured,
It was possible to put them together in a tank having outer dimensions of (width) 250 mm, D (depth) 190 mm, and H (height) 204 mm. The dimensions of the main parts are as follows. Positive and negative electrode high voltage socket (according to JIS Z4731) ...... diameter about 50mm, length about 150mm high voltage transformer (2) ……………… W × H × D = 1
00 × 120 × 100 Filament transformer (5) ……………………………………
Outer diameter 60 x thickness 30 Circuit board for high voltage (48) ……………… W × H × D =
200 × 140 × 20 (excluding height 40 of the doubler capacitor)

As described above, the DC high voltage generator of the present invention has a structure in which a high voltage generating circuit is sealed with insulating oil in an oil tank consisting of a tank case body and an upper lid. Two negative voltage high voltage sockets are installed side by side, and along with these high voltage sockets, a high voltage transformer with one secondary winding is installed with the secondary winding down. Furthermore, a circuit board on which two sets of positive voltage and negative voltage doubler rectifier circuits are mounted symmetrically is placed under the high voltage socket, and these positive and negative electrodes correspond to the positive and negative electrodes of the above two sets of doubler voltage rectifier circuits. In parallel with the upper lid, the inputs of the two sets of voltage doubler rectifier circuits are connected to the secondary windings of the high voltage transformer, and the positive and negative high voltage outputs are connected to the positive and negative electrodes, respectively. Each high voltage socket Is a circuit and structure connected. According to the present invention, with such a circuit and structure, the height of the tank is the length of the high-voltage socket, the thickness of the circuit board on which the high-voltage rectifier circuit is mounted, and the height sufficient to provide the necessary insulation distance. Since it can be manufactured with dimensions and the DC high voltage generator can be miniaturized, the X-ray apparatus main body can be miniaturized.
Further, since the amount of insulating oil in the oil tank is also reduced, the cost can be reduced and the weight can be reduced.

[Brief description of drawings]

FIG. 1 is a circuit diagram for explaining an embodiment of the present invention.

FIG. 2 is a diagram showing an example of a structure of a high voltage transformer used in one embodiment of the present invention.

FIG. 3 is a diagram for explaining ripple of a high voltage output according to an embodiment of the present invention.

FIG. 4A is a top view showing a state in which an upper lid of the oil tank is removed in the embodiment of the present invention, and FIG. 4B is a cross-sectional perspective view of the oil tank.

FIG. 5 is an explanatory diagram of a high voltage detection divider used in an embodiment of the present invention.

FIG. 6 is an explanatory diagram of a filament transformer used in an embodiment of the present invention.

FIG. 7 is a diagram showing an example of a conventional X-ray high-voltage rectification method.

[Explanation of symbols]

1 ... DC high voltage generator 2 ... High voltage transformer 3, 4 ... Double voltage rectifier circuit 5 ... Filament transformer 8 ... High frequency inverter 12, 15 ... High voltage socket 13・ ・ ・ X-ray tube 14,16 ・ ・ ・ High voltage cable 17,21 ・ ・ ・ Double voltage capacitor 18,23 ・ ・ ・ High voltage diode block 19,22 ・ ・ ・ High voltage diode block 26 ・..High voltage detecting divider 28 ... Control circuit 30 ... Tube current detecting circuit 32 ... High voltage generating circuit 41 ... Tank case body 42 ... Top lid 44,45,46,47 ... Rectangular insulation support 48 ... High-voltage circuit board 49 ... Grounding metal conductor 61 ... High-voltage detection divider 26 mounting printed circuit board 62 ... Filament transformer mounting Insulating board for

Claims (4)

[Claims] 1. A high voltage transformer having one secondary winding in an oil tank consisting of a case body and an upper lid, and a DC high voltage generating circuit for boosting / rectifying the AC high voltage from the secondary winding. In a DC high voltage generator in which is sealed with insulating oil, two high voltage sockets for the positive electrode and the negative electrode are mounted side by side on the upper lid, and the high voltage transformer is attached along these high voltage sockets. The secondary winding is attached downward, and further, the positive and negative electrodes forming the DC high voltage generating circuit
A circuit board on which a pair of voltage doubler rectifier circuits is mounted is provided below the high voltage socket, the positive electrode of the high voltage socket,
The negative electrode and the positive and negative electrodes of the above two sets of voltage-doubler rectifier circuits are arranged so as to correspond to each other and fixed substantially parallel to the upper lid. A DC high voltage generator characterized in that a high voltage output is connected to each of the positive and negative high voltage sockets. 2. A high voltage transformer having one secondary winding in an oil tank consisting of a case body and an upper lid, and a DC high voltage generating circuit for boosting and rectifying the AC high voltage from the secondary winding. In a DC high voltage generator in which is sealed with insulating oil, two high voltage sockets for the positive electrode and the negative electrode are mounted side by side on the upper lid, and the high voltage transformer is attached along these high voltage sockets. The secondary winding is attached to the upper lid with the lower side down, and the circuit board on which the positive voltage and negative voltage doubler rectifier circuits forming the DC high voltage generating circuit are mounted is placed under the high voltage socket. , The positive and negative poles of the high-voltage socket and the positive and negative poles of the above two sets of voltage doubler rectifier circuits are arranged so as to correspond to each other and fixed substantially parallel to the upper lid, and two pairs of doubler voltage rectifiers of the above positive and negative poles Near the middle of the circuit A grounding conductor for connecting them between the grounding point and the upper lid, and connecting the positive and negative high voltage outputs of the voltage doubler rectifier circuit to the positive and negative high voltage sockets, respectively. DC high voltage generator characterized by. 3. A high voltage transformer having one secondary winding in an oil tank consisting of a case body and an upper lid, and a DC high voltage generating circuit for boosting and rectifying the AC high voltage from the secondary winding. In a DC high-voltage generator in which is sealed with insulating oil, two high-voltage sockets for the positive and negative electrodes are mounted side by side on the upper lid, and the high-voltage socket is placed at a position almost equal to both of these high-voltage sockets. A circuit board, in which a voltage transformer is attached to the upper lid with its secondary winding facing downwards, and two sets of positive voltage and negative voltage doubler rectifier circuits that form a DC high-voltage generating circuit are mounted almost symmetrically,
Below the high-voltage socket, the positive and negative electrodes of the high-voltage socket and the positive and negative electrodes of the two sets of voltage-doubler rectifier circuits are arranged so as to correspond to each other and fixed substantially parallel to the upper lid. A grounding conductor is provided between the grounding point located approximately in the middle of the two sets of negative voltage doubler rectifier circuits and the upper lid, and a tube current detection line on the circuit board is connected to the grounding conductor along the grounding conductor. Extend the current detection line and connect it to the tube current detection circuit arranged outside the oil tank through the upper lid, and also connect the positive and negative high voltage outputs of the voltage doubler rectifier circuit to the positive and negative electrodes, respectively. DC high voltage generator characterized by being connected to each high voltage socket. 4. A high voltage cable connected to an X-ray tube located outside the oil tank is inserted into and connected to each of the positive and negative high voltage sockets. The X-ray apparatus according to claim 3.