JP2011192410A - X-ray high voltage device and x-ray ct device using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an X-ray high voltage device having resonance circuit configuration and attaining symmetrical pressure resistant design to achieve stable operation and high reliability by constituting a resonance circuit so that maximum voltage values applied to both ends of a primary coil are the same in a high voltage transformer which is one of components of the X-ray high voltage device, and an X-ray CT device using the X-ray high voltage device. <P>SOLUTION: The X-ray high voltage device includes: a DC power source; an inverter circuit for converting DC power output from the DC power source into AC voltage; the high voltage transformer for stepping up the AC voltage, and a rectifier for converting the stepped-up AC voltage into DC high voltage and supplying the DC high voltage to an X-ray tube. Using capacitors inserted in series into both input terminal parts of the primary coil provided at the high voltage transformer, an output terminal part of the inverter circuit is connected to both input terminal parts of the primary coil provided at the high voltage transformer, thus forming the resonance circuit configuration. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an X-ray high voltage apparatus including a resonance circuit, an X-ray apparatus and an X-ray CT apparatus using the same, and more particularly to a circuit configuration of the resonance circuit.

  The inverter circuit driven at high frequency is a power conversion system that reduces the load impedance by forming a resonance circuit in the load of the inverter circuit, and improves the power factor by bringing the resonance frequency and the inverter frequency close to each other. X-ray high voltage devices are widespread and common.

  The X-ray high voltage device is composed of a DC power source, a high voltage transformer, and a rectifier in addition to the inverter circuit, and the electric power generated by the X-ray high voltage device is supplied to the X-ray tube. The X-ray tube generates X-rays based on the power supplied by the X-ray high voltage device.

  Also in this case, the high voltage transformer having a primary winding and a secondary winding has a large leakage inductance and a secondary winding stray capacitance, which are elements of a resonance circuit. For this reason, in order to obtain an arbitrary resonance frequency, the X-ray high voltage device generally employs a system in which a capacitor is inserted in series between one of the primary windings of the high voltage transformer and the output of the inverter circuit ( Patent Document 1).

  Moreover, in order to obtain high safety and reliability, the X-ray high voltage apparatus has protective circuits and protective elements at various locations. The circuit includes not only main circuit components but also unavoidable inductor components and capacitor components, which may cause surge voltage and inrush current. Further, when the withstand voltage performance of the X-ray tube is lowered, a discharge phenomenon frequently occurs in the X-ray tube, and an inrush current may be generated inside the X-ray high voltage device, which causes the device to break down. One of the functions for protecting the apparatus from such a phenomenon is a surge absorber.

Japanese Patent Laid-Open No. 2002-65657

  FIG. 1 is a diagram in which surge absorbers ZNR101 and 102 are connected to a conventional X-ray high voltage apparatus. The surge absorbers ZNR101 and 102 each have a role of protecting the device from a surge voltage generated at the input portion of the high voltage transformer 102.

  However, in this case, one of the output terminals output from the inverter circuit 101 is connected to the input terminal of one end of the primary winding of the high voltage transformer 102 via the capacitor C101, and the output terminal output from the inverter circuit 101 is also connected. Since the other is directly connected to the input terminal of the other end of the primary winding of the high voltage transformer 102, the maximum voltage value applied to both input terminals of the primary winding as viewed from the ground point is asymmetric. For this reason, the maximum voltage values applied to the two surge absorbers ZNR101 and ZNR102 are also different from each other, and it is necessary to select a surge absorber with an appropriate rating and to design an asymmetric pressure resistance.

  Even if a surge absorber is not added, the maximum voltage value applied to both input terminals of the primary winding is asymmetrical, so the dielectric strength and creepage distance from other structures and parts to both input terminals It is necessary to take an asymmetric pressure-resistant design that takes into account. If the maximum voltage value applied to both input terminals is designed symmetrically according to the larger value, one of them is designed with a margin that is more than necessary, which is sufficient for downsizing the device. Absent.

  The asymmetric withstand voltage design as described above has a problem that the difficulty of circuit design increases, and in turn, the possibility of causing a problem with respect to the stable operation of the circuit increases.

  A DC power supply, an inverter circuit that converts DC power output from the DC power supply into an AC voltage, a high-voltage transformer that boosts the AC voltage, and converts the boosted AC voltage into a DC high voltage that is converted into an X-ray tube. An X-ray high voltage device comprising a rectifier for supplying a DC high voltage, and an inverter circuit using capacitors respectively inserted in series in both input terminal portions of a primary winding provided in the high voltage transformer Are connected to both input terminal portions of the primary winding provided in the high voltage transformer to form a resonance circuit configuration.

  According to the present invention, it is possible to provide an X-ray high voltage apparatus having stable operation and high reliability, and an X-ray CT apparatus using the same.

Configuration diagram of X-ray high-voltage device for explaining a conventional example Configuration diagram of an X-ray high voltage apparatus for explaining the first embodiment Detailed explanatory diagram of the inverter circuit 202 and the high voltage transformer 203 shown in FIG. Configuration diagram of an X-ray high voltage apparatus for explaining the second embodiment Configuration diagram of X-ray high-voltage apparatus for explaining Example 3 Configuration diagram of X-ray CT apparatus for explaining the second embodiment

  Hereinafter, preferred embodiments of an X-ray high voltage apparatus of the present invention and an X-ray CT apparatus using the same will be described in detail with reference to the accompanying drawings. Note that components having the same function are denoted by the same reference symbols throughout the drawings for describing the embodiments of the invention, and the repetitive description thereof is omitted.

  An embodiment of the present invention will be described with reference to FIGS. FIG. 2 is a configuration diagram of the X-ray high voltage apparatus of the present invention. FIG. 3 is a detailed explanatory diagram of the inverter circuit 202 and the high voltage transformer 203 shown in FIG.

  As shown in FIG. 2, the X-ray high-voltage device includes a DC power supply 201, an inverter circuit 202, a high-voltage transformer 203, a rectifier 204, capacitors C201 and C202, a transformer input surge voltage protection circuit 206, It is configured with. An X-ray tube 205 is connected to the output end of the X-ray high voltage apparatus.

  A DC power supply 201 is connected to the inverter circuit 202 and supplies DC power. The inverter circuit 202 converts the supplied DC power into a high-frequency AC voltage, and supplies the high-frequency AC voltage from the output terminal unit to the high-voltage transformer 203 connected via the capacitors C201 and C202. The high voltage transformer 203 boosts the supplied high frequency AC voltage to a high frequency high voltage, and supplies the high frequency high voltage to the rectifier 204 connected to the output stage of the high voltage transformer 203. The rectifier 204 converts the supplied high frequency high voltage into a DC high voltage, and supplies the DC high voltage to the X-ray tube 205 connected to the output stage of the rectifier 204. In this embodiment, the transformer input surge voltage protection circuit 206 for preventing a failure due to a surge voltage or an inrush current generated at the input terminal of the high voltage transformer 203 is composed of surge absorbers ZNR201 and ZNR202.

  One electrode of the surge absorbers ZNR201 and ZNR202 is connected to the input terminal portion of the high voltage transformer 203 connected to the capacitors C201 and C202, respectively. The other electrodes of the surge absorbers ZNR201 and ZNR202 are both grounded to GND. Next, the input terminal portion of the high voltage transformer 203 to which the inverter circuit 202, the high voltage transformer 203, and the surge absorbers ZNR201 and ZNR202 are connected will be described in detail with reference to FIG.

The inverter circuit 202 is configured by switching elements S301 to S304.
The switching elements S301 to S304 are made of, for example, an IGBT (Insulated Gate Bipolar Transistor), and a MOS-FET (Metal Oxide Semiconductor Field Effect Transistor) or the like can be used as the switching element. The high voltage transformer 203 includes a primary winding L301 and a secondary winding L302. Both input terminal portions of the primary winding L301 are designated as A and B, respectively. These locations A and B are locations where surge absorbers ZNR201 and ZNR202 are connected to GND as a grounding point. (The surge absorbers ZNR201 and ZNR202 are not shown.) The inverter circuit 202 includes capacitors C201 and C202, a primary winding L301 of the high-voltage transformer 203, and leakage included in the high-voltage transformer 203. A resonance circuit is formed by using inductance, stray capacitance, etc. as a load. By driving the inverter circuit 202 at a frequency close to this resonance frequency, a large output can be obtained.

Next, the operation will be described.
When the switching elements S301 and S304 are conducted (hereinafter referred to as ON) and the switching elements S303 and S302 are opened (hereinafter referred to as OFF), the current from the DC power supply 201 is sequentially switched from the switching element S301 to the capacitor C201, the primary winding L301, the capacitor C202, It returns to the DC power supply 201 through the switching element S304. On the other hand, when the switching elements S301 and S304 are OFF and the switching elements S303 and S302 are ON, the current from the DC power supply 201 is changed in order from the switching element S303 to the capacitor C202, the primary winding L301, the capacitor C201, and the switching element S302. Return to DC power supply 201. The inverter circuit 202 repeats the above two states and performs repetitive operations. At this time, the capacitors C201 and C202 are inserted into both input terminal portions of the primary winding L301, respectively, so that the maximum voltage values applied to the A and B locations are the same, and both input terminal portions of the high voltage transformer 203 With respect to the surge absorbers ZNR201 and ZNR202 connected to both input terminal portions, a symmetrical breakdown voltage design can be performed.

  As described above, according to the X-ray high voltage apparatus of this embodiment, in the X-ray high voltage apparatus provided with the resonance circuit, the output portion of the inverter circuit 202 is connected to the input portion of the high voltage transformer 203. By inserting a capacitor C201 and a capacitor C202 in series to each of the two connection lines, the withstand voltage setting of both input terminal portions of the high voltage transformer 203 and the transformer input surge voltage protection circuit 206 connected thereto can be performed. It is possible to provide an X-ray high-voltage device that is easy and can perform a reliable and stable circuit operation.

  Further, even if the transformer input surge voltage protection circuit 206 is not provided, it is easy to design the withstand voltage of both input terminal portions of the high voltage transformer 203, and it goes without saying that the same effect as described above is obtained.

  A second embodiment of the present invention will be described with reference to FIGS. A part of the description common to the first embodiment will be omitted.

FIG. 6 is a configuration diagram of the X-ray CT apparatus of the present invention.
FIG. 4 is a configuration diagram of an X-ray high voltage apparatus used in the X-ray CT apparatus shown in FIG.
The X-ray CT apparatus shown in FIG. 6 includes a scan gantry unit 601 and a console 602. The scan gantry unit 601 includes an X-ray tube 603, a rotating disk 604, a collimator 605, an X-ray detector 606, a data collection device 607, a bed 608, a gantry control device 609, a bed control device 610, And an X-ray high voltage device 611.

  The X-ray tube 603 is an apparatus that irradiates a subject placed on a bed 608 with X-rays. The collimator 605 is a device that limits the radiation range of X-rays emitted from the X-ray tube 603. The rotating disk 604 includes an opening 612 into which a subject placed on a bed 608 enters, and an X-ray tube 603 and an X-ray detector 606 are mounted to rotate around the subject. The X-ray detector 606 is a device that measures the spatial distribution of transmitted X-rays by detecting X-rays that are placed opposite to the X-ray tube 603 and transmitted through the subject, and rotates a number of X-ray detection elements. They are arranged in the rotation direction of the disk 604, or arranged two-dimensionally in the rotation direction of the rotation disk 604 and the rotation axis direction. The data collection device 607 is a device that collects the X-ray dose detected by the X-ray detector 606 as digital data. The gantry control device 609 is a device that controls the rotation of the rotating disk 604. The bed control device 610 is a device that controls the vertical movement of the bed 608. The X-ray high voltage device 611 is a device that supplies electric power to the X-ray tube 603, and details will be described later with reference to the configuration diagram of the X-ray high voltage device shown in FIG. The console 602 includes an input device 612, an image calculation device 613, a display device 614, a storage device 615, and a system control device 616.

  The input device 612 is a device for inputting a subject name, examination date and time, imaging conditions, and the like. The image computation device 613 is a device that performs CT processing on the measurement data sent from the data collection device 607 and performs CT image reconstruction. The display device 614 is a device that displays the CT image created by the image calculation device 613.

  The storage device 615 is a device that stores data collected by the data collection device 607 and image data of a CT image created by the image calculation device 613. The system control device 616 controls these devices, the gantry control device 609, the bed control device 610, and the X-ray high voltage device 611. The X-ray tube 603 is controlled by the X-ray high voltage device 611 controlling the power input to the X-ray tube 603 based on the imaging conditions input from the input device 612, in particular, the X-ray tube voltage and the X-ray tube current. The subject is irradiated with X-rays according to the imaging conditions.

  The X-ray detector 606 detects X-rays irradiated from the X-ray tube 603 and transmitted through the subject with a number of X-ray detection elements, and measures the distribution of transmitted X-rays. The rotating disk 604 is controlled by the gantry control device 609, and rotates based on the imaging conditions input from the input device 612, particularly the rotational speed. The bed 608 is controlled by the bed control device 610, and operates based on the imaging conditions input from the input device 612, particularly the helical pitch. By repeating the X-ray irradiation from the X-ray tube 603 and the measurement of the transmitted X-ray distribution by the X-ray detector 606 along with the rotation of the rotating disk 604, projection data from various angles is acquired. The acquired projection data from various angles is transmitted to the image calculation device 613. The image arithmetic device 613 reconstructs a CT image by performing back projection processing on the transmitted projection data from various angles. The CT image obtained by the reconstruction is displayed on the display device 614.

Next, an X-ray high voltage apparatus 611 used in the X-ray CT apparatus of the present embodiment will be described with reference to FIG.
4 includes a DC power supply 201, an inverter circuit 202, a high voltage transformer 403, a rectifier 404, capacitors C401 and C402, a transformer input surge voltage protection circuit 406, and a non-contact type. And a power feeding device 407. An X-ray tube 603 is connected to the output end of the X-ray high voltage device.

  The difference from the X-ray high voltage apparatus of FIG. 1 described in the first embodiment is that the power output from the inverter circuit 202 is supplied to the high voltage transformer 403 via the contactless power supply apparatus 407 in addition to the capacitors C401 and C402. By the way. The non-contact power feeding device 407 includes a primary winding L401 and a secondary winding L402 that are formed in a one-to-one contact with each other, and the primary winding L401 is on the scan gantry unit 601 side, and the secondary winding L402 is It is installed on the rotating disk 604 side. As a result, even when the rotating disk 604 rotates, the power generated on the primary winding L401 side can be transmitted to the secondary winding L402 side. Both input terminal portions of primary winding L401 are connected to capacitors C401 and C402, and both output terminal portions of secondary winding L402 are connected to both input terminal portions of the primary winding (not shown) of high voltage transformer 403, respectively. The

  The transformer input surge voltage protection circuit 406 is configured by surge absorbers ZNR401 and ZNR402, and one electrode of the surge absorbers ZNR401 and ZNR402 is connected to the secondary winding L402 of the non-contact power feeding device 407. Connected to both input terminal portions. Let these connection locations be location C and location D, respectively. The other electrodes of the surge absorbers ZNR401 and ZNR402 are both grounded to GND. Further, the inverter circuit 202 includes capacitors C401 and C402, a primary winding L401, a secondary winding L402 and a primary winding of the high voltage transformer 403, a non-contact power feeding device 407, a high voltage A resonance circuit is formed using a leakage inductance or the like included in the transformer 403 as a load. Similar to the X-ray high voltage apparatus shown in the first embodiment, a large output can be obtained by driving the inverter circuit 202 at a frequency close to the resonance frequency.

  The explanation of the operation is the same as that of the X-ray high-voltage device shown in the first embodiment except that power is transmitted by the non-contact power feeding device 407, and thus the description thereof is omitted.

In the X-ray high voltage apparatus including the non-contact power feeding device 407 used in the X-ray CT apparatus as in the present embodiment, capacitors C401 and C402 are respectively provided at both input terminal portions of the primary winding L401 of the non-contact power feeding device 407. Therefore, the maximum voltage value applied to the C and D locations is the same, and a symmetrical withstand voltage design can be performed for both input terminal portions of the high voltage transformer 403, and further connected to both input terminal portions. A symmetrical breakdown voltage design can be performed for the surge absorbers ZNR401 and ZNR402.
As described above, according to the X-ray CT apparatus of the present embodiment, for the two connection lines connected from the output portion of the inverter circuit 202 to both input terminal portions of the primary winding L401 of the non-contact power feeding device 407, X-ray high voltage that makes it easy to set the withstand voltage of both input terminals of high voltage transformer 403 and transformer input surge voltage protection circuit 406 connected to each other by inserting capacitor C401 and capacitor C402 in series. By using the apparatus, an X-ray CT apparatus capable of performing highly reliable and stable circuit operation can be provided.

  Further, even if the transformer input surge voltage protection circuit 406 is not provided, it is easy to design the withstand voltage of both input terminal portions of the high voltage transformer 403, and it goes without saying that the same effects as described above can be obtained.

  Example 3 of the present invention will be described with reference to FIG. A part of the description common to the second embodiment is omitted.

  The X-ray high voltage apparatus shown in FIG. 5 is another embodiment of the X-ray high voltage apparatus used in the X-ray CT apparatus shown in the second embodiment.

  The X-ray high voltage apparatus shown in FIG. 5 includes two connection lines connected from the output portion of the inverter circuit 202 to both input terminal portions of the primary winding L401 of the contactless power supply device 407, and two contactless power supply devices 407. Capacitors C501 to C504 are divided and connected in series to two connection lines connected from both output terminal portions of the next winding L402 to both input terminal portions of the high voltage transformer 403, respectively. By dividing the capacitors C501 to C504 in this way, the rating of one capacitor can be reduced with respect to the capacitors C401 and C402 shown in the third embodiment.

  As described above, according to the X-ray high voltage device of this embodiment, the capacitor C501 is divided in series between the inverter circuit 202 and the non-contact power feeding device 407, between the non-contact power feeding device 407 and the high voltage transformer 403, respectively. Since the rating of each capacitor can be reduced and the external dimensions can be reduced by inserting ~ C504, the X shown in Example 2 is taken into account in consideration of component placement and selection of general-purpose products that require a narrow layout. In addition to the line high-voltage apparatus, the X-ray high-voltage apparatus of this embodiment can be selected as the X-ray high-voltage apparatus of the X-ray CT apparatus. When the reduction of the centrifugal force by the rotating disk 604 is more important, it is desired to reduce the weight of the rotating disk 604. In such a case, by using the X-ray high voltage apparatus of the second embodiment, the weight of the rotating disk 604 can be further reduced compared to the X-ray high voltage apparatus of the present embodiment. It is possible to select the best form according to the situation.

  Further, even if the transformer input surge voltage protection circuit 406 is not provided, it is easy to design the withstand voltage of both input terminal portions of the high voltage transformer 403, and it goes without saying that the same effects as described above can be obtained.

  101 inverter circuit, 102 high voltage transformer, 201 DC power supply, 202 inverter circuit, 203 high voltage transformer, 204 rectifier, 205 X-ray tube, 206 transformer input surge voltage protection circuit, 403 high voltage transformer, 404 rectifier, 406 Transformer input surge voltage protection circuit, 407 Contactless power supply, 601 Scan gantry section, 602 console, 603 X-ray tube, 604 rotating disk, 605 collimator, 606 X-ray detector, 607 data collection device, 608 bed, 609 Gantry control device, 610 bed control device, 611 X-ray high voltage device, 612 opening, 613 image calculation device, 614 display device, 615 storage device, 616 system control device, C101, C201, C202, C401, C402, C501 ~ C504 Capacitor, ZNR101, 102, ZNR201, 202, ZNR401, 402 Surge absorber, S301 ~ S304 Switching element, L301 Primary winding of high voltage transformer 203 L302 Secondary winding of high voltage transformer 203, L401 Non-contact supply Electrical equipment Primary winding of device 407 L402 Secondary winding of non-contact power feeder 407

Claims (7)

A DC power source, an inverter circuit that converts DC power output from the DC power source into an AC voltage, a high-voltage transformer that boosts the AC voltage, and converts the boosted AC voltage into a DC high voltage, A rectifier for supplying the DC high voltage to the tube, and an X-ray high voltage apparatus comprising:
Using capacitors inserted in series in both input terminal portions of the primary winding provided in the high voltage transformer, both the output terminal portion of the inverter circuit and the primary winding provided in the high voltage transformer. An X-ray high voltage device comprising a resonance circuit configuration in which an input terminal portion is connected.   The X-ray high voltage apparatus according to claim 1, further comprising a transformer input surge voltage protection circuit between both input terminal portions of the primary winding of the high voltage transformer and a reference potential.   The X-ray high voltage apparatus according to claim 2, further comprising the transformer input surge voltage protection circuit configured by using a surge absorber. A DC power source, an inverter circuit that converts DC power output from the DC power source into an AC voltage, a non-contact power feeding device that includes a primary winding and a secondary winding that transmit the AC voltage, and the transmitted AC An X-ray CT apparatus comprising: a high-voltage transformer that boosts a voltage; and a rectifier that converts the boosted AC voltage to a DC high voltage and supplies the DC high voltage to an X-ray tube.
Using capacitors inserted in series in both input terminal portions of the primary winding provided in the non-contact power feeding device, both the output terminal portion of the inverter circuit and both primary windings provided in the non-contact power feeding device. An X-ray CT apparatus comprising: an input terminal portion; and a resonance circuit configuration together with a primary winding provided in the high voltage transformer.   Using capacitors inserted in series in both input terminal portions of the primary winding provided in the high voltage transformer, both output terminal portions of the secondary winding of the non-contact power feeding device, and the high voltage transformer 5. The X-ray CT apparatus according to claim 4, further comprising a resonance circuit configuration in which both input terminal portions of the primary winding provided in the circuit are connected.   The X-ray CT apparatus according to claim 4, further comprising a transformer input surge voltage protection circuit between both input terminal portions of the primary winding of the high voltage transformer and a reference potential.   The X-ray CT apparatus according to claim 6, further comprising the transformer input surge voltage protection circuit configured using a surge absorber.

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