JPH04116400U - X-ray device - Google Patents

Abstract

(57) [Summary] [Purpose] To miniaturize the high voltage transformer and high voltage rectifier circuit in a monotank type X-ray device. [Structure] The secondary winding of the high voltage transformer is made into one, the winding start of this secondary winding is grounded, and the input terminal of the positive polarity output half-wave voltage doubler rectifier circuit is connected to the winding end of the secondary winding. Connect the output terminal of the half-wave voltage doubler rectifier circuit with positive polarity output to the anode of the X-ray tube, and connect the input terminal of the half-wave voltage doubler rectifier circuit with negative polarity output to the end of the above secondary winding. Then, the output terminal of the half-wave voltage doubler rectifier circuit with negative polarity output was connected to the cathode of the X-ray tube.

Description

[Detailed explanation of the idea]

0001

[Industrial application field]

This invention isolates the high voltage transformer, high voltage rectifier circuit, and X-ray tube in one tank. The X The present invention relates to a so-called monotank type X-ray device.

0002

[Conventional technology]

In recent years, as the power supply systems of X-ray equipment have become higher frequency, the mono-tank type X-ray equipment is also using higher frequencies. If a mono-tank type X-ray device is made to operate at a higher frequency, the model Notank-type X-ray equipment can be made smaller, and if the tank is made smaller, operability will be improved. , there is a great advantage in increasing the frequency of a monotank type X-ray device.

0003 FIG. 4 is a circuit diagram showing an example of a conventional monotank type X-ray apparatus.

0004 This conventional device includes a DC power source 1 such as a storage battery or a rectifier, and a A high frequency inverter 2 that generates a high frequency voltage as an input and a metal seal at ground potential. It is composed of a container 3a (so-called mono tank). Inside the metal enclosure 3a includes a high-voltage transformer T3, a bridge rectifier 4, and filter capacitors C5 and C6. An X-ray tube 5 is enclosed together with an insulating medium such as insulating oil. High voltage transformer T3 The primary winding N1 is connected to the output of the high frequency inverter 2 outside the enclosure 3a. ing.

[0005] In addition, the winding start b of the secondary winding N2 of the high voltage transformer T3 is directly grounded, and the high voltage The winding start c of the secondary winding N3 of the transformer T3 is grounded via the tube current detection circuit 6. It is. The high voltage side d at the end of winding of secondary winding N2 and the high voltage side at the end of winding of secondary winding N3 e is connected to the AC input point of the bridge rectifier 4. Bridge rectifier 4 The DC output includes filter capacitors C5 and C6 and anode A of the X tube 5, respectively. The cathode K is connected. Note that the fibres, which are necessary to operate the X-ray tube 5, are The filament power supply 7 and filament transformer T2 are not directly related to this invention. , the explanation thereof will be omitted.

[0006] Next, the operation of the above conventional example will be explained.

[0007] The high frequency output voltage of the inverter 2 is supplied to the primary winding N1 of the high voltage transformer T3. The two secondary windings N2 and N3 of the high voltage transformer T3 are wound in opposite directions. The windings have the same shape, and by connecting the winding starts b and c, the same polarity can be directly connected. are connected in series, and the neutral point a of the output of the X-ray power supply device, which is the point of this series connection, is grounded. There is. Note that the black dots in each winding indicate polarity.

[0008] In the above conventional example, if the voltage generated in the secondary windings N2 and N3 is E, then The AC input voltage of the edge rectifier 4 is 2E, and the rectified voltage is 2E. Secondary winding N 2. Since the series connection point a of N3 is grounded, the positive output of the bridge power supply circuit 4 The voltage is +E, and the negative output voltage is -E. These voltages are applied to the anode of the X-ray tube 5. It is supplied to the cathode A and the cathode K.

[0009] In this way, the series connection point of secondary windings N2 and N3 is grounded and the anode voltage is set to +E. The reason why the cathode voltage is -E is to facilitate the high voltage insulation structure. For example, if you configure an X-ray tube with a rated voltage of 125 kV with one side grounded (positive or negative), Therefore, a 125kV insulation structure is required, but if the center point is grounded as shown above, A 62.5kV insulation structure is sufficient. The insulation structure becomes more accommodating at an accelerated rate due to voltage reduction. Therefore, the effect of reducing the voltage to 1/2 is very large. In addition, such a high frequency In the wave type X-ray power supply, the capacitance of filter capacitors C5 and C6 is small. Even if the voltage is applied between the anode A and cathode K of the X-ray tube 5, it has a sufficient filtering effect. It is possible to reduce high frequency ripples in the applied voltage.

0010 The frequency component of this high frequency ripple voltage is twice the inverter operating frequency, The higher the frequency of the inverter 2, the more the ripple is reduced.

[0011] The high voltage transformer T3 of such a conventional X-ray apparatus has a winding structure as shown in FIG. has. A primary winding N1 is wound around one leg of the iron core, and two windings are placed on top of this primary winding N1. Secondary windings N2 and N3 are wound separately. Winding start terminal b of each secondary winding N2, N3 , c are connected externally and serve as neutral points. Symbols d and e indicate the high voltage side terminals of the winding. It is.

0012

[Problem that the idea aims to solve]

In the above conventional example, the secondary windings N2 and N3 of the transformer T3 do not generate high voltage. Usually, it takes several thousand turns to wrap it, and it requires interlayer paper between each layer to wind it. The shape of the winding becomes larger, and the insulation between the windings N2 and N3 and the windings N2, N Due to the insulation between T3 and the iron core, the transformer T3 itself becomes large. therefore ,Realistically, even if the power supply is made to have a high frequency as described above, the transformer T3 is required from the viewpoint of insulation. It is said that it is difficult to downsize the metal enclosure 3a because it is difficult to downsize the metal enclosure 3a. There's a problem.

[0013] This invention reduces the size of the high-voltage transformer and high-voltage rectifier circuit in a monotank X-ray device. The purpose is to provide an X-ray device that can perform

[0014]

[Means to solve the problem]

This invention combines the secondary winding of a high voltage transformer into one, and connects the beginning of the winding of this secondary winding. ground, and connect the input terminal of the half-wave voltage doubler rectifier circuit with positive polarity output to the end of the above secondary winding. Connect the output terminal of the half-wave voltage doubler rectifier circuit with positive polarity output to the anode of the X-ray tube. Connect the input terminal of the half-wave voltage doubler rectifier circuit with negative polarity output to the end of the secondary winding. Next, connect the output terminal of the half-wave voltage doubler rectifier circuit with negative polarity output to the cathode of the X-ray tube. It is something that

[0015]

【Example】

FIG. 1 is a circuit diagram showing one embodiment of the present invention.

[0016] In FIG. 1, the same members as those in the conventional example described above are given the same reference numerals. Ru.

[0017] In FIG. 1, a high frequency inverter 2 converts the DC voltage of a DC power supply 1 into a high frequency voltage. The output of this high frequency inverter 2 is It is supplied to the primary winding N1 of the high voltage transformer T1. Secondary winding of high voltage transformer T1 The wire N2 is single, i.e. only one secondary winding is provided, and the winding Terminal f is grounded. The high voltage terminal g at the end of the winding is a half-wave double voltage of the positive polarity output. Connect to the input terminal of the rectifier circuit 8 and the input terminal of the negative polarity output half-wave voltage doubler rectifier circuit 9 has been done.

[0018] The half-wave voltage doubler rectifier circuit 8 with positive polarity output includes a capacitor C1 and a filter capacitor. The input terminal of the rectifier circuit 8 is a high voltage voltage source. The winding end of the lance T1 is connected to the high voltage terminal g, and the output terminal of the rectifier circuit 8 is connected to the X-ray It is connected to anode A of tube 5. Diodes D1 and D2 have the same polarity and are connected to each other. is connected in series with the diode D2, and the cathode side of the diode D2 is connected to the output side of the rectifier circuit 8. , the anode side of the diode D1 is grounded. Capacitor C1 is a high voltage connected between the high voltage terminal g at the end of winding T1 and the midpoint of diodes D1 and D2. , capacitor C2 is connected between the output side of the rectifier circuit 8 and ground.

[0019] The half-wave voltage doubler rectifier circuit 9 with negative polarity output includes a capacitor C3 and a filter capacitor. The input terminal of the rectifier circuit 9 is a high voltage voltage source. The winding end of the lance T1 is connected to the high voltage terminal g, and the output terminal of the rectifier circuit 9 is connected to the X-ray It is connected to the cathode K of the tube 5. Diodes D3 and D4 have the same polarity and are connected to each other. and the anode side of the diode D4 is connected to the output side of the rectifier circuit 9. , the cathode side of the diode D3 is grounded. Capacitor C3 is a high voltage connected between the high voltage terminal g at the end of winding T1 and the midpoint of diodes D3 and D4. , a capacitor C4 is connected between the output side of the rectifier circuit 9 and ground.

[0020] FIG. 2 is a diagram showing an example of the structure of the high voltage transformer T1 in the above embodiment.

[0021] The primary winding N1 is wound around one leg of the iron core of the high voltage transformer T1, and the secondary winding N1 is wound on top of it. 2 is wrapped. Note that the terminal f is the winding start terminal that is grounded, and the terminal g is the winding start terminal that is grounded. This is the high voltage side terminal.

[0022] Note that even if the ground capacitance of the wiring is used as the filter capacitors C2 and C4, Alternatively, the ground capacity of the X-ray tube 5 may also be used.

[0023] The two voltage doubler rectifier circuits 8 and 9 increase the voltage of the secondary winding N2 of the high voltage transformer T1. The pressure E is rectified to +2E and -2E, and supplies a voltage of 4E to the X-ray tube 5. However, Therefore, the voltage of the secondary winding N2 may be 1/2 of the conventional voltage. Inside capacitors C2 and C4 Since the point is grounded, the voltage to ground at each terminal of the X-ray tube 5 is 1/2 of the tube voltage. , This provides the same insulating structure advantages as the conventional one.

[0024] In addition, as shown in Figure 3, the ripple voltage of each capacitor C2 and C4 is Since the operating frequency is the same as that of inverter 2, and the phases are opposite to each other, The harmonic ripple to ground applied to node A and cathode K is canceled out. cormorant. As a result, the ripple voltage between the anode and cathode of the X-ray tube 5 is It can be equal to or smaller than that of conventional bridge rectification.

[0025] Therefore, according to the above embodiment, one secondary winding of the high voltage transformer T1 is sufficient. , and the high voltage transformer T1 by the positive and negative voltage doubler rectifier circuits 8 and 9. Since the secondary winding voltage of 1/4 of the voltage of the X-ray tube 5 is sufficient, the secondary winding voltage in the conventional device is The winding may have a number of turns that is half the number of turns of the winding. Instead, current capacity is twice that of the secondary winding in conventional equipment, but originally an X-ray transformer was It is designed for short-time ratings, so even if the current capacity increases, the windings will not be too large. do not have. Therefore, the number of secondary windings is one, and the winding voltage is 1/2 of the conventional one. Therefore, it is necessary to use a smaller iron core than the conventional one for the high voltage transformer T1. Therefore, the high voltage transformer T1 can be made smaller.

[0026] In addition, the number of high-voltage diodes is four, the same as before, but the withstand voltage of each is lower than before. 1/2 is sufficient. Also, the current capacity of diodes D1, D2, D3, and D4 is doubled. However, high-voltage diodes generally have a higher withstand voltage than a higher current capacity. If it were to be raised, the overall size would be large and it would be technically difficult. therefore, In the above example, a diode with low breakdown voltage can be used, so a small diode is used. can do. In particular, for X-ray power supplies, the operating time is as short as a few seconds. There are many high voltage diodes D1, D2, D3, D4 and the secondary winding N2 of transformer T1. It is also possible to overload the

[0027] In contrast to these advantages of miniaturization, in the above embodiment, the boost capacitors C1 and C 3 increases, but the higher the operating frequency of the inverter 2, the higher the boost capacitor C1 , C3 can be a small capacitor. In addition, the boost capacitor Since the withstand voltage of C1 and C3 is sufficient to be 1/4 of the tube voltage, the boost capacitor C1, As C3, a capacitor of relatively small size can be used.

[0028] Note that the half-wave voltage doubler rectifier circuits 8 and 9 in the above embodiment are one-stage Cockcroft rectifiers. It can be regarded as a Twalton circuit (CW circuit), so when using a CW circuit with two or more stages, It is generally considered that the same effects as those of the above embodiments can be obtained even if the above embodiments are used. However, Noboru The number of voltage capacitors increases in proportion to the number of stages n, and the output voltage of the CW circuit is The number of stages is n to the third power, and the ripple is proportional to the square of n, so a large current (several tens of mA to several hundred mA) ), it is necessary to use many large capacitors, It cannot be downsized. Therefore, from the point of view of downsizing the monotank, As can be seen, it is not a good idea to use the above embodiment in a CW circuit with two or more stages. Special In addition, the present invention is useful for high-power X-ray equipment with large tube currents of several kW to several tens of kW. Ru.

[0029] Furthermore, in the above embodiment, the pulsating current flowing through the grounded diodes D1 and D3 The average value of the current is equal to the tube current, and the charging/discharging alternating current of distributed capacitance flows as in the conventional case. Therefore, the value of tube current can be calculated from the current flowing through diode D1 or D3. can be detected accurately. Further, in the above embodiment, a high frequency replica of the voltage of the X-ray tube 5 is used. If it is not necessary to reduce the voltage so much, connect a capacitor C to each positive and negative pole. 2. It is also possible to remove C4 and rely only on the ground capacitance of the X-ray tube 5 and its wiring. Further, in the above embodiment, the metal enclosure 3 is used, but instead of this, a conductive container 3 is used. Encapsulation containers using electrically conductive resin or composite materials with a metal film formed on insulating resin. The used enclosure container may also be used.

[0030] In addition, in the experiment, to output a tube voltage of 100 kV and a tube current of 100 mA, it took 20 A kHz high frequency inverter and a transformer that generates a secondary winding voltage of approximately 25kV. , 1000pF 30kV boost capacitor and 60kV high voltage diode 4 With 400pF capacitors for each positive and negative side, sufficient practical output characteristics can be achieved. I was able to get it.

[0031]

[Effect of the idea]

According to the present invention, a voltage doubler rectifier circuit with positive and negative symmetry is used. This makes it possible to reduce the number of secondary windings to one, and also to reduce the number of turns. By doing so, the transformer can be made smaller, and it is also possible to The ability to use a diode reduces the size of the diode, making mono This has the effect of reducing the size of the tank.

[Brief explanation of drawings]

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

FIG. 2 is an explanatory diagram of an example of the winding structure of the high voltage transformer T1 in the above embodiment.

FIG. 3 is a diagram showing an example of the anode-cathode voltage of the X-ray tube 5 in the above embodiment.

FIG. 4 is a circuit diagram showing an example of a conventional X-ray device.

FIG. 5 is an explanatory diagram of the winding structure of the high voltage transformer T3 in the conventional example.

[Explanation of symbols]

2...High frequency inverter, 3...Metal enclosure container, 5...X-ray tube, 6...Tube current detection circuit, 8... Half-wave voltage doubler rectifier circuit with positive polarity output, 9...Half-wave voltage doubler rectifier circuit with negative polarity output, T1...High voltage transformer.

Claims (1)

[Scope of utility model registration request] Claim 1: A high-voltage transformer, a high-voltage rectifier circuit, and an X-ray tube are housed in one enclosure, and one of the high-voltage transformers is
In an X-ray apparatus in which a secondary winding is driven by a high-frequency inverter, the high-voltage transformer has only one secondary winding, the winding start of this secondary winding is grounded, and the high-voltage rectifier circuit has a positive polarity. It is composed of a half-wave voltage doubler rectifier circuit for output and a half-wave voltage doubler rectifier circuit for negative polarity output, and the input terminal of the half-wave voltage doubler rectifier circuit for positive polarity output is connected to the end of the secondary winding of the high voltage transformer. The output terminal of the positive polarity output half-wave voltage doubler rectifier circuit is connected to the anode of the X-ray tube, and the input terminal of the negative polarity output half-wave voltage doubler rectifier circuit is connected to the secondary of the high voltage transformer. The output terminal of the negative polarity output half-wave voltage doubler rectifier circuit is connected to the winding end of the winding, and the output terminal of the negative polarity output half-wave voltage doubler rectifier circuit is connected to the
An X-ray device characterized in that it is connected to a cathode of a ray tube.