Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J29/00—Details of cathode-ray tubes or of electron-beam tubes of the types covered by group H01J31/00
  • H01J29/003—Arrangements for eliminating unwanted electromagnetic effects, e.g. demagnetisation arrangements, shielding coils

Definitions

• the present invention relates to an X-ray image tube distortion correction apparatus that corrects distortion of a visible light image by removing the influence of an external magnetic field.
• an X-ray image tube is used in medical X-ray diagnostic equipment, industrial nondestructive inspection equipment, etc., converts an X-ray image into an electron beam image on an input surface, and transmits electrons in an electron lens. It has the function of accelerating and focusing and drawing a visible light image on the output surface.
• the strength of the external magnetic field is sufficiently smaller than the geomagnetism, there will be no problem, but it will be more than the geomagnetism.
• the image processing is performed even with a change or displacement that is so small that the visible light image becomes distorted or cannot be felt, it becomes a problem.
• the first conventional technique for suppressing the intrusion of an external magnetic field by installing a magnetic shield on the input surface side also cancels the external magnetic field by passing a current through a coil provided on the input surface side.
• Third conventional technology that obtains data on how much S-shaped distortion is generated by seeing through a guide in advance, and performs image processing based on that data for correction. Technology is adopted.
• a magnetic field sensor, an angle sensor, or the like is installed outside the tube container of the X-ray image tube, and the magnetic field is generated based on the output of the sensor force according to the change in motion.
• the current value necessary for canceling out is read by the table force, and the current is passed through the coil (see, for example, pages 3-5 of JP-A-63-121239, FIGS. 2 and 6).
• a coil is installed around the input surface, and a magnetic field sensor is installed in a space surrounded by the input surface and the coil. Based on the output of the magnetic field sensor, A control circuit force is also obtained for the current flowing through the coil (see, for example, page 34 of FIGS. 7 and 65756 and FIGS. 1 and 2).
• Each employs a method of detecting the state of the X-ray image tube and automatically obtaining a current to be passed through the coil from the control circuit based on the detected data. Also, in combination with the third conventional technology, based on the detection data, it is corrected by image processing in combination with data on how much S-shaped distortion that has been acquired in advance in that state. A method has also been proposed (for example, see pages 4 to 6 and FIGS. 1 and 2 of Japanese Patent Laid-Open No. 2003-180666).
• the magnetic field sensor When the magnetic field sensor is installed in the space surrounded by the input surface and the coil as in the second prior art 2, the magnetic field sensor is placed at a position where the X-ray incident on the X-ray image tube is not blocked. Place however, in order to install the magnetic field sensor in a space that is surrounded by the input surface and the coil and does not block the X-rays, the magnetic field sensor must be installed very close to the coil. . Then, because the magnetic field generated by the coil force must cancel the magnetic field close to the center axis of the X-ray image tube, the strength of the magnetic field generated by the coil force is stronger than the external magnetic field entering the X-ray image tube. It will be stronger than that. Therefore, there is a problem that the external magnetic field cannot be detected by the magnetic field sensor.
• the present invention has been made in view of these points, and an object thereof is to provide an X-ray image tube distortion correction apparatus capable of automatically correcting distortion.
• the present invention is a distortion correction apparatus for an X-ray image tube that covers a vacuum envelope having an input surface, an electron lens, and an output surface with a magnetic shield, and is surrounded by the magnetic shield of the X-ray image tube.
• the X-ray is disposed in a region that does not block the X-rays incident on the input surface and that has an external force of the X-ray image tube and a magnetic field strength equivalent to the strength of the external magnetic field entering the electron lens region.
• An external force of the image tube A magnetic field sensor that detects a magnetic field that enters the electron lens region and an external magnetic field that is disposed on the input surface region side of the X-ray image tube and enters the electron lens region of the X-ray image tube A magnetic field generation unit that generates a magnetic field that cancels out the magnetic field, and a control unit that generates a magnetic field that cancels the external magnetic field by the magnetic field generation unit based on detection of the external magnetic field by the magnetic field sensor. That
• the present invention is an X-ray image tube distortion correction apparatus for covering a vacuum envelope having an input surface, an electron lens, and an output surface with a magnetic shield, the magnetic shield of the X-ray image tube. And an outside region that enters the electron lens region from the outside of the X-ray image tube and is disposed in an outer region including the electron lens region side of the input surface region of the X-ray image tube.
• a magnetic field sensor that detects a magnetic field and an external magnetic field that is disposed on the input surface region side of the X-ray image tube and enters the external force electron lens region of the X-ray image tube
• a magnetic field generation unit that generates a magnetic field that cancels the magnetic field
• a control unit that generates a magnetic field that cancels the external magnetic field by the magnetic field generation unit based on detection of the external magnetic field by the magnetic field sensor.
• the magnetic field sensor is surrounded by the magnetic shield of the X-ray image tube, and the X-ray incident on the input surface is not blocked. Since it is placed in a region where the magnetic field strength is equivalent to the strength of the external magnetic field that penetrates into the lens region, the effect of the magnetic field generated by the magnetic field generator arranged on the input surface region side of the X-ray image tube is reduced, The external magnetic field that enters the electron lens area from the outside of the X-ray image tube can be detected with high accuracy, and the magnetic field generator can generate an appropriate magnetic field to cancel the external magnetic field. Thus, distortion of the visible light image can be reliably corrected.
• the magnetic field sensor is arranged in an area surrounded by the magnetic shield of the X-ray image tube and in an outer area including the electron lens area side from the input surface area of the X-ray image tube, the X-ray image
• the effect of the magnetic field generated by the magnetic field generator located on the input surface area side of the tube is reduced, and the external magnetic field that enters the electron lens area from the outside of the X-ray image tube can be accurately detected.
• An appropriate magnetic field for canceling the external magnetic field can be generated, and distortion of the visible light image can be reliably corrected by removing the influence of the external magnetic field.
• FIG. 1 is an explanatory view schematically showing a cross section of an X-ray image tube distortion correction apparatus showing a first embodiment of the present invention.
• FIG. 2 is an explanatory view schematically showing a cross section of an X-ray image tube distortion correction apparatus showing a second embodiment of the present invention.
• FIG. 1 shows a first embodiment.
• 11 is an X-ray image tube, and this X-ray image tube 11 has a vacuum envelope 12, and an input window 13 is formed on the X-ray incident side of the vacuum envelope 12.
• An output window 14 is formed on the opposite side to the input window 13.
• an input surface 15 for converting X-rays into electrons is emitted inside the input window 13, and an electron beam is converted into a visible light image and output inside the output window 14.
• Output surface 16 Is provided.
• an electron lens 17 that accelerates and focuses the electron beam is formed along the path of electrons that travel from the input surface 15 toward the output surface 16.
• the electron lens 17 includes a cathode (not shown) that applies a negative voltage to the input surface 15, an anode 18 that applies a high positive voltage to the output surface 16, a plurality of focusing electrodes 19 between the cathode and the anode 18, and the like. It is configured.
• the periphery of the vacuum envelope 12 excluding the input surface 15 and the output surface 16 is covered with a magnetic shield 20 made of a material that blocks magnetic influences such as permalloy.
• the X-ray image tube 11 includes an input surface region 21 in which the input surface 15 is located, an output surface region 22 in which the output surface 16 is located, and the input surface region 21 and the output surface region 22.
• An area where the electron lens 17 is located between them is an electron lens area 23.
• the distortion correction device 31 of the X-ray image tube 11 uses a magnetoelectric conversion element or the like that detects an external magnetic field m that enters the X-ray image tube 11 from the outside due to geomagnetism or magnetism generated from an external device.
• Magnetic field sensor 32, coil 33 as a magnetic field generator that generates a reverse magnetic field to cancel the external magnetic field m entering the X-ray image tube 11 from the outside, and a coil to generate an appropriate reverse magnetic field from this coil 33 It has a control unit 34 that controls the value of the current flowing through it.
• the coil 33 is disposed along the periphery of the input surface 15 between the vacuum envelope 12 and the magnetic shield 20 so as not to block X-rays incident on the input surface 15, that is, the input surface. Located in region 21.
• the magnetic field sensor 32 is surrounded by the magnetic shield 20 between the vacuum envelope 12 and the magnetic shield 20, and does not block the X-rays incident on the input surface 15, but the external force electrons of the X-ray image tube 11. It is disposed in a region where the magnetic field strength is equivalent to the strength of the external magnetic field m that enters the lens region 23.
• the X-ray image tube is corrected so that it is corrected above the central axis 1 la of the X-ray image tube 11! / ,!
• the region where the external force of 11 has a magnetic field strength equivalent to the strength of the external magnetic field m entering the electron lens region 23 is the outer peripheral region of the electron lens region 23.
• the electron beam perpendicular to the central axis 11a of the X-ray image tube 11 and emitted from the input surface 15 and accelerated and focused by the electron lens 17 is obtained.
• the child e is disposed closer to the input surface 15 than the plane A including the point P that intersects the central axis 11 a of the X-ray image tube 11. Therefore, the magnetic field sensor 32 is positioned away from the input surface region 21 surrounded by the input surface 15 and the coil 33 of the X-ray image tube 11 toward the electron lens region 23 side, and more than the input surface than the plane A. On the 15th side, it is disposed in the outer peripheral region of the electron lens region 23. By setting the position of the magnetic field sensor 32 on the input surface 15 side with respect to the plane A, the external magnetic field m entering the electron lens region 23 can be reliably detected.
• the magnetic field sensor 32 cannot be installed at a desired position due to the presence of a structure constituting the product.
• a plurality of magnetic field sensors 32a and 32b are installed in the tube axis direction of the X-ray image tube 11 so as to sandwich the position. Further, a plurality of magnetic field sensors 32 a and 32 b may be arranged in the circumferential direction of the X-ray image tube 11. Therefore, at least one of the magnetic field sensors 32a and 32b is arranged at each of a plurality of different positions in the tube axis direction of the X-ray image tube 11.
• a plurality of magnetic field sensors 32a and 32b are used as the magnetic field sensor 32. These magnetic field sensors 32a and 32b may be installed with different detection directions. For example, one of the magnetic field sensors 32a and 32b has the detection direction parallel to the central axis 11a of the X-ray image tube 11, and the other one has the detection direction as the central axis of the X-ray image tube 11. 11 The direction crossing a.
• control unit 34 analyzes the influence of the external magnetic field m based on the signal output from the magnetic field sensor 32, and provides the coil 33 necessary for generating a reverse magnetic field that cancels the external magnetic field m. It has a function of obtaining the current value and controlling the current of the obtained current value to flow through the coil 33.
• the influence of the external magnetic field m is analyzed based on a signal obtained by synthesizing signals output from the plurality of magnetic field sensors 32a and 32b. At this time, synthesis may be performed while weighting the outputs of the magnetic field sensors 32a and 32b.
• FIG. 1 an example of the external magnetic field m when the correction by the distortion correction device 31 is not performed above the central axis 11a of the X-ray image tube 11 is shown.
• the external magnetic field m is the X-ray image.
• the external magnetic field m also acts on the magnetic field sensor 32 positioned in the outer peripheral region of the electron lens region 23 having a magnetic field strength equivalent to the strength of the external magnetic field m entering the electron lens region 23.
• the control unit 34 analyzes the influence of the external magnetic field m based on the signal output from the magnetic field sensor 32, and cancels the external magnetic field m. A current value applied to the coil 33 necessary to generate the current is obtained, and control is performed so that the current having the obtained current value flows through the coil 33.
• a reverse magnetic field is generated by passing a current through the coil 33, and the external magnetic field m is canceled by the reverse magnetic field.
• FIG. 1 an example of the external magnetic field m when corrected by the distortion correction device 31 is shown below the central axis 11a of the X-ray image tube 11.
• the external magnetic field m does not enter the electron lens region 23. Therefore, at the stage of accelerating and focusing the electron e by the electron lens 17, it is possible to prevent the trajectory of the electron e from being bent by the external magnetic field m, and it is possible to reliably correct the distortion of the visible light image.
• the magnetic field sensor 32 is surrounded by the magnetic shield 20 of the X-ray image tube 11 and the X-ray incident on the input surface 15 is not blocked, and the external cover of the X-ray image tube 11 is also Since it is arranged in the outer peripheral area of the electron lens area 23 where the intensity of the magnetic field equivalent to the intensity of the external magnetic field m that penetrates into the electron lens area 23, it is arranged on the input surface area 21 side of the X-ray image tube 11
• the magnetic field generated by the generated coil 33 is reduced, and the external magnetic field m entering the electron lens region 23 from outside the X-ray image tube 11 can be detected with high accuracy. Therefore, an appropriate reverse magnetic field for canceling the external magnetic field m can be generated by the coil 33, and distortion of the visible light image can be corrected reliably without the influence of the external magnetic field m.
• a plurality of magnetic field sensors 32 are used when the magnetic field sensor 32 cannot be installed at a desired position due to the presence of a structure constituting the product. Only need be used.
• FIG. 2 shows a second embodiment.
• the same reference numerals are given to the same functional parts as those in FIG. 1, and detailed description thereof is omitted.
• FIG. 2 an example of the external magnetic field m is shown in the case where the correction is made by the distortion correcting device 31 above the central axis 1 la of the X-ray image tube 11, and the central axis of the X-ray image tube 11 is shown.
• An example of the external magnetic field m when corrected by the distortion correction device 31 is shown below 11a.
• a magnetic circuit 41 is installed in the vicinity of the magnetic field sensor 32, and the magnetic circuit 41 can guide the external magnetic field m to the magnetic field sensor 32.
• the magnetic circuit 41 Since the magnetic circuit 41 is intended to change the direction of the magnetic field, it is desirable that the magnetic permeability is at least a force permeability of 10 or more that can function as long as the magnetic permeability is not vacuum.
• the influence of the magnetic field generated by the magnetic field generator disposed on the input surface region side of the X-ray image tube is reduced, and the external force of the X-ray image tube enters the electron lens region.
• the external magnetic field can be detected with high accuracy, and an appropriate magnetic field for canceling the external magnetic field can be generated at the magnetic field generator, and the distortion of the visible light image can be reliably corrected by eliminating the influence of the external magnetic field.

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• Physics & Mathematics (AREA)
• Electromagnetism (AREA)
• Image-Pickup Tubes, Image-Amplification Tubes, And Storage Tubes (AREA)

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• 2005
  • 2005-11-09 JP JP2005325187A patent/JP2007134135A/ja active Pending
• 2006
  • 2006-11-09 CN CNA2006800019425A patent/CN101103431A/zh active Pending
  • 2006-11-09 WO PCT/JP2006/322384 patent/WO2007055285A1/ja not_active Ceased
  • 2006-11-09 EP EP06823271A patent/EP1968097A4/en not_active Withdrawn
• 2007
  • 2007-07-09 US US11/822,634 patent/US20080067399A1/en not_active Abandoned

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