EP2620041A2 - Émetteur de rayons x compact - Google Patents

Émetteur de rayons x compact

Info

Publication number
EP2620041A2
EP2620041A2 EP11827134.5A EP11827134A EP2620041A2 EP 2620041 A2 EP2620041 A2 EP 2620041A2 EP 11827134 A EP11827134 A EP 11827134A EP 2620041 A2 EP2620041 A2 EP 2620041A2
Authority
EP
European Patent Office
Prior art keywords
circuit
resistor
connection
output
capacitor
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP11827134.5A
Other languages
German (de)
English (en)
Inventor
Dongbing Wang
Dave Reynolds
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Moxtek Inc
Original Assignee
Moxtek Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from US12/890,325 external-priority patent/US8526574B2/en
Application filed by Moxtek Inc filed Critical Moxtek Inc
Publication of EP2620041A2 publication Critical patent/EP2620041A2/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J35/00—X-ray tubes
    • H01J35/02—Details
    • H01J35/16—Vessels; Containers; Shields associated therewith
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J35/00—X-ray tubes
    • H01J35/22—X-ray tubes specially designed for passing a very high current for a very short time, e.g. for flash operation
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05G—X-RAY TECHNIQUE
    • H05G1/00—X-ray apparatus involving X-ray tubes; Circuits therefor
    • H05G1/08—Electrical details
    • H05G1/10—Power supply arrangements for feeding the X-ray tube
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05G—X-RAY TECHNIQUE
    • H05G1/00—X-ray apparatus involving X-ray tubes; Circuits therefor
    • H05G1/08—Electrical details
    • H05G1/26—Measuring, controlling or protecting
    • H05G1/30—Controlling
    • H05G1/32—Supply voltage of the X-ray apparatus or tube
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J2235/00—X-ray tubes
    • H01J2235/02—Electrical arrangements
    • H01J2235/023—Connecting of signals or tensions to or through the vessel

Definitions

  • An x-ray source is comprised of an x-ray tube and a power supply. Transformers and a high voltage sensing resistor in the power supply can significantly cause the power supply to be larger than desirable.
  • An x-ray source can have a high voltage sensing resistor used in a circuit for sensing the tube voltage.
  • the high voltage sensing resistor due to a very high voltage across the x-ray tube, such as around 10 to 200 kilovolts, can have a very high required resistance, such as around 10 mega ohms to 100 giga ohms.
  • the high voltage sensing resistor can be a surface mount resistor and the surface of the substrate that holds the resistor material can have surface dimensions of around 12 mm by 50 mm in some power supplies. Especially in miniature and portable x-ray tubes, the size of this resistor can be an undesirable limiting factor in reduction of size of a power supply for these x-ray tubes.
  • X-ray tubes can have a transformer ("filament transformer") for transferring an alternating current signal from an alternating current (AC) source at low bias voltage to an x-ray tube electron emitter, such as a filament, at a very high direct current (DC) voltage, or bias voltage, such as around 10 to 200 kilovolts.
  • U.S. Patent 7,839,254 incorporated herein by reference, describes one type of filament transformer.
  • X-ray tubes can also have a transformer (called a “high voltage transformer” or “HV transformer” herein) for stepping up low voltage AC, such as around 10 volts, to higher voltage AC, such as above 1 kilovolt.
  • This higher voltage AC can be used in a high voltage generator, such as a Cockcroft-Walton multiplier, to generate the very high bias voltage, such as around 10 to 200 kilovolts, of the x-ray tube filament or cathode with respect to the anode.
  • the size of both the high voltage transformer and the filament transformer can be a limiting factor in reduction of the size of the x-ray source.
  • the present invention is directed towards a more compact, smaller high voltage device, including smaller, more compact x-ray sources.
  • the present invention is directed to a circuit for supplying AC power to a load in a circuit in which there is a large DC voltage differential between an AC power source and the load.
  • Capacitors are used to provide voltage isolation while providing efficient transfer of AC power from the AC power source to the load.
  • the DC voltage differential can be at least about 1 kV.
  • these capacitors can replace the filament transformer. This invention satisfies the need for a compact, smaller high voltage device, such as a compact, smaller x-ray source.
  • the present invention can be used in an x-ray tube in which (1 ) the load can be an electron emitter which is electrically isolated from an anode, and (2) there exists a very large DC voltage differential between the electron emitter and the anode.
  • AC power supplied to the electron emitter can heat the electron emitter and due to such heating, and the large DC voltage differential between the electron emitter and the anode, electrons can be emitted from the electron emitter and propelled towards the anode.
  • only one transformer for an electron emitter and a high voltage generator is needed, by connecting a first alternating current source for the electron emitter or filament in parallel with the input to the high voltage generator thus reducing size and cost by using a the high voltage generator for voltage isolation rather than using a separate transformer for voltage isolation.
  • the capacitors of the high voltage generator provide isolation between the electron emitter or filament, at very high DC voltage, and the alternating current source for the electron emitter or filament, which is at a low DC voltage potential.
  • two different circuits can utilize the same transformer core, thus reducing size and cost by utilizing one core instead of two.
  • Each can have a different frequency in order to avoid one circuit from interfering with the other circuit.
  • the input circuit for each can have a frequency that is about the same as the resonant frequency of the output circuit.
  • the high voltage sensing resistor can be disposed directly on the cylinder of the x-ray tube.
  • the sensing resistor can be improved tube stability due to removal of static charge on the surface of the x-ray tube cylinder that was generated by the electrical field within x-ray tube.
  • FIG. 1 is a schematic of a circuit for supplying alternating current to a load, with a high voltage DC power source on the load side of the circuit, in accordance with an embodiment of the present invention
  • FIG. 2 is a schematic of a circuit for supplying alternating current to a load, with a high voltage DC power source on the AC power source side of the circuit, in accordance with an embodiment of the present invention
  • FIG. 3 is a schematic of a circuit for supplying alternating current to a load, with a high voltage DC power source connected between the load side of the circuit and the AC power source side of the circuit, in accordance with an embodiment of the present invention
  • FIG. 4 is a schematic cross-sectional side view of an x-ray tube utilizing a circuit for supplying alternating current to a load in accordance with an
  • FIG. 5 is a flow chart depicting a method for heating an electron emitter in an x-ray tube in accordance with an embodiment of the present invention.
  • FIG. 6 is a schematic cross-sectional side view of a power source in which a high voltage multiplier is used to separate an alternating current source, at low or zero bias voltage, from a load at a very high bias voltage, which load is powered by this alternating current source;
  • FIG. 7 is a schematic cross-sectional side view of a power source for an x- ray tube electron emitter in which a high voltage multiplier is used to separate an alternating current source, at low or zero bias voltage, from the electron emitter at a very high bias voltage, which electron emitter is powered by this alternating current source;
  • FIG. 8 is a schematic cross-sectional side view of a Cockcroft-Walton multiplier
  • FIG. 9 is a schematic cross-sectional side view of an alternating current source and step-up transformer for supplying alternating current to a high voltage generator;
  • FIG. 10 is a schematic cross-sectional side view of a multiple channel transformer in which two circuits utilize the same transformer core;
  • FIG. 1 1 is a schematic cross-sectional side view of a multiple channel transformer in which two circuits utilize the same transformer core, one of these circuits is used to supply power to an x-ray tube electron emitter and the other is used to supply power to a high voltage generator;
  • FIG. 12 is a schematic cross-sectional side view of an x-ray tube cylinder with multiple wraps of a first resistor, used as a high voltage sensing resistor, in accordance with an embodiment of the present invention
  • FIG. 13 is a schematic cross-sectional side view of an x-ray tube cylinder and a first resistor disposed on the cylinder in a zig-zag shaped pattern, used as a high voltage sensing resistor, in accordance with an embodiment of the present invention
  • FIG. 14 is a schematic cross-sectional side view of an x-ray tube cylinder with multiple wraps of a first resistor, used as a high voltage sensing resistor, and a second resistor across which voltage drop is measured, in accordance with an embodiment of the present invention.
  • the term “substantially” refers to the complete or nearly complete extent or degree of an action, characteristic, property, state, structure, item, or result.
  • an object that is “substantially” enclosed would mean that the object is either completely enclosed or nearly completely enclosed.
  • the exact allowable degree of deviation from absolute completeness may in some cases depend on the specific context. However, generally speaking the nearness of completion will be so as to have the same overall result as if absolute and total completion were obtained.
  • the use of “substantially” is equally applicable when used in a negative connotation to refer to the complete or near complete lack of an action, characteristic, property, state, structure, item, or result.
  • capacitor means a single capacitor or multiple capacitors in series.
  • high voltage or “higher voltage” refer to the DC absolute value of the voltage.
  • negative 1 kV and positive 1 kV would both be considered to be “high voltage” relative to positive or negative 1 V.
  • negative 40 kV would be considered to be “higher voltage” than 0 V.
  • low voltage or “lower voltage” refer to the DC absolute value of the voltage.
  • negative 1 V and positive 1 V would both be considered to be “low voltage” relative to positive or negative 1 kV.
  • positive 1 V would be considered to be “lower voltage” than 40 kV.
  • a circuit shown generally at 10, for supplying AC power to a load 14, includes an AC power source 13 having a first connection 13a and a second connection 13b, a first capacitor 1 1 having a first connection 1 1 a and a second connection 1 1 b, and a second capacitor 12 having a first connection 12a and a second connection 12b.
  • the first connection of the AC power source 13a is connected to the first connection on the first capacitor 1 1 a.
  • the second connection of the AC power source 13b is connected to the first connection on the second capacitor 12a.
  • the AC power source 13, the first and second connections on the AC power source 13a-b, the first connection on the first capacitor 1 1 a, and the first connection on the second capacitor 12a comprise a first voltage side 21 of the circuit.
  • the circuit 10 for supplying AC power to a load further comprises the load 14 having a first connection 14a and a second connection 14b.
  • the second connection of the first capacitor 1 1 b is connected to the first connection on the load 14a and the second connection of the second capacitor 12b is connected to the second connection on the load 14b.
  • the load 14, the first and second connections on the load 14a-b, the second connection on the first capacitor 1 1 b, and the second connection on the second capacitor 12b comprise a second voltage side 23 of the circuit.
  • the first and second capacitors 1 1 , 12 provide voltage isolation between the first and second voltage sides 21 , 23 of the circuit, respectively.
  • a high voltage DC source can provide at least 1 kV DC voltage differential between the first 21 and second 23 voltage sides of the circuit.
  • the high voltage DC power source 15 can be electrically connected to the second voltage side 23 of the circuit 10, such that the second voltage side of the circuit is a substantially higher voltage than the first voltage side 21 of the circuit.
  • the high voltage DC power source 15 can be electrically connected to the first voltage side 21 of the circuit 20, such that the first voltage side of the circuit has a
  • the high voltage DC power source 15 can be electrically connected between the first 21 and second 23 voltage sides of the circuit 30 to provide a large DC voltage potential between the two sides of the circuit.
  • the DC voltage differential between the first 21 and second 23 voltage sides of the circuit can be substantially greater than 1 kV.
  • the DC voltage differential between the first and second voltage sides of the circuit can be greater than about 4 kV, greater than about 10 kV, greater than about 20 kV, greater than about 40 kV, or greater than about 60 kV.
  • the AC power source 13 can transfer at least about 0.1 watt, at least about 0.5 watt, at least about 1 watt, or at least about 10 watts of power to the load 14.
  • capacitors sometimes a circuit such as the example circuit displayed in FIGs. 1 -3 needs to be confined to a small space, such as for use in a portable tool. In such a case, it is desirable for the capacitors to have a small physical size. Capacitors with lower capacitance C are typically smaller in physical size. However, use of a capacitor with a lower capacitance can also result in an increased capacitive reactance X c . A potential increase in capacitive reactance X c due to lower capacitance C of the capacitors can be compensated for by increasing the frequency f supplied by the AC power source, as shown in the formula: c 2 * pi * f * C '
  • the capacitance of the first and second capacitors can be greater than about 10 pF or in the range of about 10 pF to about 1
  • the alternating current may be supplied to the circuit 10 at a frequency / of at least about 1 MHz, at least about 500 MHz, or at least about 1 GHz.
  • the capacitive reactance X c is about 3.2.
  • the capacitive reactance X c of the first capacitor 1 1 can be in the range of 0.2 to 12 ohms and the capacitive reactance X c of the second capacitor 12 can be in the range of 0.2 to 12 ohms.
  • the first capacitor 1 1 can comprise at least 2 capacitors connected in series and the second capacitor 12 can comprise at least 2 capacitors connected in series.
  • the load 14 in the circuit 10 can be an electron emitter such as a filament in an x-ray tube.
  • the circuits 1 0, 20, 30 for supplying AC power to a load 14 as described above and shown in FIGs. 1 -3 may be used in an x-ray tube 40.
  • the x-ray tube 40 can comprise an evacuated dielectric tube 41 and an anode 44 that is disposed at an end of the evacuated dielectric tube 41 .
  • the anode can include a material that is configured to produce x-rays in response to the impact of electrons, such as silver, rhodium, tungsten, or palladium.
  • the x-ray tube further comprises a cathode 42 that is disposed at an opposite end of the evacuated dielectric tube 41 opposing the anode 44.
  • the cathode can include an electron emitter 43, such as a filament, that is configured to produce electrons which can be accelerated towards the anode 44 in response to an electric field between the anode 44 and the cathode 42.
  • a power supply 46 can be electrically coupled to the anode 44, the cathode 42, and the electron emitter 43.
  • the power supply 46 can include an AC power source for supplying AC power to the electron emitter 43 in order to heat the electron emitter, as described above and shown in FIGs. 1 -3.
  • the power supply 46 can also include a high voltage DC power source connected to at least one side of the circuit and configured to provide: (1 ) a DC voltage differential between the first and second voltage sides of the circuit; and (2) the electric field between the anode 44 and the cathode 42.
  • the DC voltage differential between the first and second voltage sides of the circuit can be provided as described above and shown in FIGs. 1 -3.
  • the capacitors 1 1-12 can replace a transformer, such as a filament transformer in an x-ray source.
  • This invention satisfies the need for a compact, smaller high voltage device, such as a compact, smaller x-ray source.
  • a method 50 for providing AC power to a load 14 is disclosed, as depicted in the flow chart of FIG. 5.
  • the method can include capacitively coupling 51 an AC power source 13 to a load 14.
  • a high voltage DC power source 15 can be coupled 52 to one of the load 14 or the AC power source 13 to provide a DC bias of at least 1 kV between the load 14 and the AC power source 13.
  • An alternating current at a selected frequency and power can be directed 53 from the AC power source 13 across the capacitive coupling to the load 14.
  • the DC power source 15 can provide a DC voltage differential between the load 14 and the AC power source 13 that is substantially higher than 1 kV.
  • the DC voltage differential can be greater than about 4 kV, greater than about 20 kV, greater than about 40 kV, or greater than about 60 kV.
  • the power transferred to the load 14 can be at least about 0.1 watt, at least about 0.5 watt, at least about 1 watt, or at least about 10 watts.
  • the AC power source 13 can be capacitively coupled to the load 14 with single capacitors or capacitors in series.
  • the capacitance of the capacitors, or capacitors in series can be greater than about 10 pF or in the range of about 10 pF to about 1
  • the selected frequency may be at least about 1 MHz, at least about 500 MHz, or at least about 1 GHz.
  • the AC power coupled to the load 14 can be used to heat the load 14.
  • the load 14 can be an x-ray tube electron emitter, such as a filament.
  • a power source 60 comprising a first alternating current source 64a connected in series with a first capacitor 61 a.
  • the first alternating current source 64a can be configured to operate at a first amplitude or peak voltage of about 10 volts. In one embodiment, the first amplitude can be less than about 20 volts.
  • the first alternating current source 64a can have a bias voltage of 0 so that for example the voltage can alternate between about +10 and -10 volts.
  • the first alternating current source 64a can be configured to be operated at a first frequency. In one embodiment, the first frequency can have a value of greater than about 10 megahertz. In another embodiment, the first frequency can have a value of greater than about 100 megahertz.
  • the power source 60 further comprises a second alternating current source 64b connected in parallel with the first alternating current source 64a and the first capacitor 61 a.
  • the second alternating current source 64b can be configured to operate at a second amplitude or peak voltage of about 100 volts. In one embodiment, the second amplitude can be greater than about 1 kilovolts DC.
  • the second alternating current source 64b can have a bias voltage of 0 so that for example the voltage can alternate between about +100 and -100 volts.
  • the second alternating current source 64a can be configured to be operated at a second frequency. In one embodiment, the second frequency can have a value of between about 10 kilohertz to about 10 megahertz.
  • the power source 60 further comprises a high voltage generator 67 having two connection points at a low voltage end 62 and two connection points at a high voltage end 63.
  • the high voltage generator 67 can develop a voltage differential between the low voltage end and the high voltage end of greater than about 10 kilovolts.
  • the first alternating current source 64a and the first capacitor 61 a and the second alternating current source 64b can be connected in parallel with the two connection points 62 at the low voltage end of the high voltage generator 67.
  • the power source further comprises a load 66 connected in parallel with the two connection points 63 at the high voltage end of the high voltage generator 67.
  • a second capacitor 61 b can be connected in series with a load 46.
  • the first frequency can have a value that is at least 3 times greater than the second frequency. In another embodiment, the first frequency can have a value that is at least 10 times greater than the second frequency. It can be desirable to have a very large difference between the first and second frequency.
  • a relatively lower second frequency can result in a high impedance to the alternating current from the second alternating current source 64b at the first capacitor 61 a and at the second capacitor 61 b. This minimizes any influence from the higher amplitude second alternating current source 64b on the first alternating current source 64a and load 66.
  • a higher first frequency allows the alternating current from the first alternating current source to pass the first capacitor 61 a and the second capacitor 61 b with smaller voltage drop.
  • the second amplitude can have a value that is at least 3 times greater than the first amplitude. In another embodiment, the second amplitude can have a value that is at least 10 times greater than the first amplitude. It can be desirable for the first amplitude to be lower because alternating current from the first alternating current source 64a can be used for heating the x-ray tube filament and a lower amplitude, such as around 10 volts, can be sufficient for this purpose. Also, a lower first amplitude can result in minimal effect on the high voltage generator 67 from the first alternating current source 64a.
  • the second amplitude can be higher because alternating current from the second alternating current source 64b can be used for generating a high bias voltage through the high voltage generator 67and a higher amplitude, such as greater than around 100 volts, may be needed for this purpose.
  • the power source 60 described previously can be used to supply power to an x-ray source 70.
  • the x-ray source 70 can comprise an x-ray tube 40 with an insulative cylinder 41 , an anode 44 disposed at one end of the insulative cylinder 41 , and a cathode 42 at an opposing end of the insulative cylinder from the anode.
  • the cathode can include an electron emitter 43, such as a filament.
  • the electron emitter 43 and the second capacitor 61 b can be connected in series to each other and parallel to the connection points 63 at the high voltage end of the high voltage generator 67.
  • the anode can be electrically grounded 72.
  • the first alternating current source 64a can drive alternating current and power at the electron emitter 43.
  • the second alternating current source 64b can create high voltage at the high voltage generator 67, creating a voltage differential between the cathode 42 and the anode 44 of greater than about 10 kilovolts.
  • the voltage differential between the cathode 42 and the anode 44 and the alternating current at the electron emitter 43 can cause electrons to be emitted from the electron emitter 43 and propelled towards the anode 44.
  • the high voltage generator 67 can be a Cockcroft- Walton multiplier 80.
  • Diodes D1 -1 1 in the Cockcroft-Walton multiplier 80 can have a forward voltage of greater than about 10 volts.
  • Diode D1 -1 1 forward voltage can be higher than the first amplitude such that alternating current from the first alternating current source 64a will not cause any substantial amount of current to pass through these diodes D1 -1 1 .
  • the second alternating current source 64b can comprise an alternating current source 91 connected in series with input windings 94 on a step-up transformer 92.
  • Output windings 95 on the step-up transformer 92 can be connected in parallel, at connection points 93a-b, with the first alternating current source 64a and the first capacitor 61 a.
  • this configuration can allow use of an alternating current source 91 which can supply AC at an amplitude of around 10 volts to be used, along with the step-up transformer, to supply alternating current, at an amplitude of around 100 to 1000 volts, to the high voltage generator 67.
  • Capacitance of the first and second capacitors can be chosen by balancing the desirability of higher capacitance for less power loss with lower capacitance for smaller physical size and lower cost.
  • the first capacitor 61 a can have a capacitance of between about 10 picofarads to about 10 microfarads and the second capacitor 61 b can have a capacitance of between about 10 picofarads to about 10 microfarads.
  • a multiple channel transformer 100 comprising a single transformer core 101 with at least two input circuits 102a-b and at least two output circuits 102c-d.
  • a first input circuit 102a can be wrapped 103a at least one time around the transformer core 101 and configured to carry an alternating current signal at a first frequency F-i .
  • a first output circuit 102c comprises a first output winding 103c. The first output winding 103c can be wrapped at least one time around the transformer core 101 .
  • a second input circuit 102b can be wrapped 103b at least one time around the transformer core 101 and configured to carry an alternating current signal at a second frequency F 2 .
  • a second output circuit 102d comprises a second output winding 103d. The second output winding 103d can be wrapped at least one time around the transformer core 101 .
  • the first output circuit 102c has a resonant frequency which can be the about the same as the first frequency F-i .
  • the second output circuit 102d has a resonant frequency which can be about the same as the second frequency F 2 .
  • Circuit design resulting in substantially different resonant frequencies between the two output circuits 102c-d can result in (1 ) the first input circuit 102a inducing a current in the first output circuit 102c with negligible inducement of current from the second input circuit 102b, and (2) the second input circuit 102b inducing a current in the second output circuit 102d with negligible inducement of current from the first input circuit 102a.
  • the first frequency Fi can be ten times or more greater than the second frequency F 2 , F-i ⁇ 10* F 2 .
  • the first frequency Fi can be at least 10 to 1000 times greater than the second frequency F 2 .
  • the second frequency F 2 can be ten times or more greater than the first frequency F 2 , F 2 ⁇ 10* F-i .
  • the second frequency F 2 can be 10 to 1000 times greater than the first frequency F-i.
  • Alternating current sources 104a-b can provide alternating current at the desired frequencies.
  • the resonant frequency of the first output circuit 102c can be between about 1 megahertz to about 500 megahertz and the resonant frequency of the second output circuit 102d can be between about 10 kilohertz to about 1 megahertz.
  • the resonant frequency of the second output circuit 102d can be between about 1 megahertz to about 500 megahertz and the resonant frequency of the first output circuit 102c can be between about 10 kilohertz to about 1 megahertz.
  • the first output circuit 102c can further comprise a first output circuit capacitor 105c, having a first output capacitance C 0 i , in parallel with the first output winding 103c.
  • the first output winding 103c can have a first output inductance L 0 i.
  • the second output circuit 102d can further comprise a second output circuit capacitor 105d, having a second output capacitance C o2 , in parallel with the second output winding 103d.
  • the second output winding 103d can have a second output inductance L o2 .
  • an inverse square root of the product of the first output capacitance and the first output inductance does not equal an inverse square root of the product of the second output capacitance and the second output inductance
  • the second frequency F 2 can equal the
  • the first output circuit 102c can supply power to a load 106.
  • the second output circuit can supply power to a high voltage generator 107.
  • High DC voltage potential from the high voltage generator 107 can supply high DC voltage potential to the alternating current signal at the load 106 on the first output circuit 102c.
  • a resistor 108 can be used in the connection between the high voltage generator 107 and the first output circuit 102c.
  • the high voltage generator 107 can be a Cockcroft-Walton multiplier 80 as shown in FIG. 8.
  • the various embodiments of the multiple channel transformer 100 described previously can be used in an x-ray source 1 10, as illustrated in FIG. 1 1 .
  • the x-ray source 1 10 can comprise a multiple channel transformer 100 and an x-ray tube 40.
  • the x-ray tube 40 can comprise an insulative cylinder 41 , an anode 44 disposed at one end of the insulative cylinder, and a cathode 42 disposed at an opposing end of the insulative cylinder 41 from the anode 44.
  • the cathode 42 can include an electron emitter 43, such as a filament.
  • the first output circuit 102c can provide an alternating current signal to the electron emitter 43.
  • the second output circuit 102d can provide alternating current to a high voltage generator 107.
  • the high voltage generator 107 can generate a high DC voltage potential.
  • the high DC voltage potential can be connected to the first output circuit 102c, thus providing a very high DC bias to the filament while also providing an alternating current through the electron emitter 43.
  • the anode 44 can be connected to ground 72.
  • a voltage differential of at least 10 kilovolts can exist between the anode 44 and the cathode 42. Due to this large voltage differential between the anode 44 and the cathode 42, and due to heat from the alternating current through the electron emitter 43, electrons can be emitted from the electron emitter 43 and propelled towards the anode 44.
  • High Voltage Sensing Resistor
  • an x-ray source 120 comprising an x-ray tube 40 and a line of insulative material, comprising a first resistor R1 .
  • the x-ray tube comprises an insulative cylinder 41 , an anode 44 disposed at one end of the insulative cylinder, and a cathode 42 disposed at an opposing end of the insulative cylinder 41 from the anode 44.
  • the first resistor R1 has a first end 124 which is attached to either the anode 44 or the cathode 42, and a second end 125 which is configured to be connected to an external circuit.
  • the first end 124 of the first resistor R1 is shown attached to the cathode 42.
  • the first end 124 of the first resistor R1 is shown attached to the anode 44.
  • the first end 124 of the first resistor R1 may be attached to either the cathode 42 or to the anode 44.
  • a resistance r1 across the first resistor R1 from one end to the other end can be very large. In one embodiment, a resistance r1 across the first resistor R1 from one end to the other end can be at least about 10 mega ohms. In another embodiment, a resistance r1 across the first resistor R1 from one end to the other end can be at least about 1 giga ohm. In another embodiment, a resistance r1 across the first resistor R1 from one end to the other end can be at least about 10 giga ohms. In another embodiment, a resistance r1 across the first resistor R1 from one end to the other end can be at least about 100 giga ohms.
  • the first resistor R1 can wrap around a
  • the first resistor R1 can wrap around a circumference of the cylinder 41 at least one time. In another embodiment, the first resistor R1 can wrap around a circumference of the cylinder 41 at least twenty-five times.
  • the first resistor R1 can be any electrically insulative material that will provide the high resistance required for high voltage applications.
  • the first resistor R1 is a dielectric ink painted on a surface of the cylinder 41 .
  • MicroPen Technologies of Honeoye Falls, NY has a technology for applying a thin line of insulative material on the surface of a cylindrical object.
  • a cylinder 41 of an x-ray tube 40 can be turned on a lathe-like tool and the insulative material is painted in a line on the exterior of the cylinder 41.
  • the second end 125 of the first resistor R1 can be attached to a second resistor R2, such that the two resistors are connected in series.
  • Voltage AV can be measured across the second resistor R2 by a voltage measurement device connected across the second resistor R2.
  • the second resistor R2 can have a lower resistance than the first resistor R1 .
  • the second resistor R2 can have a resistance r2 of at least 1 kilo ohm less than a resistance r1 of the first resistor R1 .
  • the second resistor R2 can have a resistance r2 of at least 1 mega ohm less than a resistance r1 of the first resistor R1 .
  • the second resistor R2 can have a resistance r2 of less than about 1 mega ohm.
  • the second resistor R2 can have a resistance r2 of less than about 1 kilo ohm.
  • the second resistor R2 can have a resistance r2 of less than about 100 ohms.
  • the first resistor R1 need not wrap around the cylinder but can be disposed in any desired shape on the cylinder, as long as the needed resistance from one end to another is achieved.
  • the first resistor R1 is disposed in a zig-zag like pattern on the insulative cylinder 41 .
  • the second resistor R2 can be disposed on the cylinder 41 .
  • the second resistor R2 can wrap around the cylinder 41 at least one time.
  • the second resistor R2 can be disposed on the cylinder 41 in a zig-zag like pattern or any other pattern.
  • the second resistor R2 can be a dielectric ink painted on a surface of the cylinder 41.
  • the first resistor and / or the second resistor can comprise beryllium oxide (BeO), also known as beryllia.
  • BeO beryllium oxide
  • Beryllium oxide can be beneficial due to its high thermal conductivity, thus providing a more uniform temperature gradient across the resistor.
  • the second resistor R2 can be connected to ground or any reference voltage at one end and to the first resistor R1 at an opposing end.
  • a method for sensing voltage across an x-ray tube can comprise:
  • insulative material on a surface of an x-ray tube cylinder 41 , the insulative material comprising a first resistor R1 ;
  • V V2*( - ri + r2
  • V is a voltage across the x-ray tube
  • V2 is a voltage across the second resistor
  • r1 is a resistance of the first resistor
  • r2 is a resistance of the second resistor

Landscapes

  • Health & Medical Sciences (AREA)
  • General Health & Medical Sciences (AREA)
  • Toxicology (AREA)
  • X-Ray Techniques (AREA)

Abstract

La présente invention a trait à un émetteur de rayons X compact qui peut inclure un circuit (10) permettant de fournir un isolement de la tension fiable entre les côtés de basse tension et de haute tension (21, 23) du circuit tout en permettant le transfert de l'alimentation en courant alternatif entre les côtés de basse tension et de haute tension du circuit vers un émetteur d'électrons à tube à rayons X (43). Des condensateurs (11, 12) permettent de fournir l'isolation entre les côtés de basse tension et de haute tension du circuit. L'émetteur de rayons X (110) peut utiliser les condensateurs d'un générateur haute tension (67) en vue de fournir un isolement de la tension. Un émetteur de rayons X compact (110) peut comprendre un noyau de transformateur unique (101) afin de transférer le courant alternatif provenant de deux sources de courant alternatif (104a, 104b) vers un émetteur d'électrons (43) et un générateur haute tension (107). Un émetteur de rayons X compact (120) peut comprendre une résistance de détection de haute tension (R1) qui est disposée sur un cylindre (41) d'un tube à rayons X (40).
EP11827134.5A 2010-09-24 2011-07-15 Émetteur de rayons x compact Withdrawn EP2620041A2 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
US12/890,325 US8526574B2 (en) 2010-09-24 2010-09-24 Capacitor AC power coupling across high DC voltage differential
US42040110P 2010-12-07 2010-12-07
PCT/US2011/044168 WO2012039823A2 (fr) 2010-09-24 2011-07-15 Émetteur de rayons x compact

Publications (1)

Publication Number Publication Date
EP2620041A2 true EP2620041A2 (fr) 2013-07-31

Family

ID=45874276

Family Applications (1)

Application Number Title Priority Date Filing Date
EP11827134.5A Withdrawn EP2620041A2 (fr) 2010-09-24 2011-07-15 Émetteur de rayons x compact

Country Status (4)

Country Link
EP (1) EP2620041A2 (fr)
JP (1) JP2013543218A (fr)
KR (1) KR20130138785A (fr)
WO (1) WO2012039823A2 (fr)

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8995621B2 (en) 2010-09-24 2015-03-31 Moxtek, Inc. Compact X-ray source
US8526574B2 (en) 2010-09-24 2013-09-03 Moxtek, Inc. Capacitor AC power coupling across high DC voltage differential
US9173623B2 (en) 2013-04-19 2015-11-03 Samuel Soonho Lee X-ray tube and receiver inside mouth
CN105425086B (zh) * 2016-01-16 2018-03-16 哈尔滨工业大学 模拟阴极与电推力器耦合放电电流振荡的阴极独立寿命测试外回路
US10499484B2 (en) * 2017-11-16 2019-12-03 Moxtek, Inc. X-ray source with non-planar voltage multiplier

Family Cites Families (6)

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Publication number Priority date Publication date Assignee Title
US4504895A (en) * 1982-11-03 1985-03-12 General Electric Company Regulated dc-dc converter using a resonating transformer
DE10159897A1 (de) * 2001-12-06 2003-06-26 Philips Intellectual Property Spannungsversorgung für Röntgengenerator
WO2004103033A1 (fr) * 2003-05-15 2004-11-25 Hitachi Medical Corporation Dispositif de generation de rayons x
US7151818B1 (en) * 2005-06-08 2006-12-19 Gary Hanington X-Ray tube driver using AM and FM modulation
US7397896B2 (en) * 2006-03-15 2008-07-08 Siemens Aktiengesellschaft X-ray device
FR2941587B1 (fr) * 2009-01-28 2011-03-04 Gen Electric Alimentation electrique d'un tube a rayons x, procede d'alimentation et systeme d'imagerie associes

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO2012039823A3 *

Also Published As

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WO2012039823A2 (fr) 2012-03-29
WO2012039823A3 (fr) 2012-08-09
JP2013543218A (ja) 2013-11-28
KR20130138785A (ko) 2013-12-19

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