Claims
- 1. An x-ray generator comprising:
- a generally toroidal housing having an evacuated interior;
- an annular anode surface mounted in the toroidal housing interior, the anode surface being in thermal communication with a cooling fluid passage such that cooling fluid can be circulated contiguous to the anode surface for removing heat;
- a cathode assembly including a multiplicity of cathode cups arranged in an annular ring within the housing opposite the anode surface, each of the cathode cups including an individual gate grid, a switching means for selectively biasing the gate grids to permit and prevent electron beams from flowing from the cathode cups to the anode, and a biasing means for selectively scanning an electron beam generated by each cathode cup along an arc segment of the anode surface.
- 2. The x-ray generator as set forth in claim 1 wherein each of the cathode cups is insulated from the housing and each other and wherein the switching means selectively switches a biasing potential between at least one selected cathode cups and the anode surface.
- 3. An x-ray generator comprising:
- a generally toroidal housing having an evacuated interior;
- an annular anode surface mounted in the toroidal housing interior, the anode surface being in thermal communication with a cooling fluid passage such that cooling fluid can be circulated contiguous to the anode surface for removing heat;
- a cathode assembly including:
- a cathode cup which holds a cathode filament which is heated by a current flowing therethrough to emit the electron beam;
- the cathode cup being mounted to a first electrical insulator;
- an annular ring on which the first insulator is supported;
- a motor means for rotating the annular ring;
- a means for magnetically levitating the annular ring within the toroidal housing;
- one end of the cathode filament being connected with the cathode cup and the other end of the cathode filament being connected with a secondary winding extending around a portion of the first electrical insulator;
- an electrical connector extending through the first electrical insulator from the cathode cup to a means which is biased to the cathode potential, the secondary winding being connected with the electrical connector;
- a second electrical insulator surrounding the secondary winding; and
- a primary winding wound around the second electrical insulator, such that the primary winding is isolated from the secondary winding, the primary winding being connected with a means for controlling current flow through the cathode filament, whereby the means for controlling current flow through the cathode filament is isolated therefrom.
- 4. An x-ray generator comprising:
- a generally toroidal housing having an evacuated interior and an annular x-ray permeable window;
- an annular anode surface mounted in the toroidal housing interior, the anode surface being in thermal communication with a cooling fluid passage such that cooling fluid can be circulated contiguous to the anode surface for removing heat;
- a cathode assembly rotatably received in the toroidal housing, the cathode assembly including:
- an annular ring rotatably received in the toroidal housing evacuated interior, the annular ring having a smaller diameter surface toward a center of the toroidal housing, a larger diameter surface opposite to the smaller diameter surface, and a pair of oppositely disposed side edges,
- an active magnetic levitation bearing means including (i) annular permanent magnet rings mounted to the annular ring along each of the smaller diameter surface, the larger diameter surface, the pair of both side edges, (ii) a permanent magnet ring mounted to the toroidal housing adjacent the permanent magnet ring mounted to one of the larger and smaller diameter surfaces and the permanent magnets mounted to one of the side edges, and (iii) a first controllable electromagnetic ring stationarily mounted to the toroidal housing adjacent the permanent magnet mounted to the other of the larger and smaller diameter surfaces and a second controllable electromagnetic ring mounted to the toroidal housing adjacent the permanent magnet ring mounted to the other side edge,
- at least one electron beam generating means mounted to the annular ring for rotation therewith;
- a means for transferring a filament current from a filament current source exterior to the toroidal housing to the electron beam generating means mounted to the rotatable annular ring in the toroidal housing;
- a large diameter induction motor having a stator mounted to the toroidal housing and a rotor connected with the annular ring for rotating the annular ring and the electron beam generating means within the toroidal housing.
- 5. The x-ray generator as set forth in claim 4 further including a mechanical bearing means for supporting the annular ring in the event of a failure magnetic levitation bearing means.
- 6. An x-ray generator comprising:
- a generally toroidal housing having an evacuated interior;
- an annular anode surface mounted in the toroidal housing interior, the anode surface being in thermal communication with a cooling fluid passage such that cooling fluid can be circulated contiguous to the anode surface for removing heat;
- a cathode assembly mounted on an annular surface disposed within the toroidal housing including a means for emitting electrons to form an electron beam that strikes the anode surface;
- an annular rotating capacitor plate mounted to the annular ring in a capacitively coupled relationship to a stationary capacitor plate mounted to the housing, the rotating capacitor plate being connected with the electron emitting means for controlling electrical power thereto and the stationary cathode plate being connected with an AC power source;
- a means for moving the electron beam to at least a multiplicity of points around the anode surface.
- 7. An x-ray generator comprising:
- a generally toroidal housing having an evacuated interior and an annular x-ray permeable window facing a central axis of the toroidal housing;
- an annular anode surface mounted in the toroidal housing interior, the anode surface being in thermal communication with a cooling fluid passage such that cooling fluid can be circulated contiguous to the anode surface for removing heat;
- a cathode assembly including;
- an annular ring rotatably disposed within the evacuated interior of the toroidal housing and centered around the central axis,
- a means for emitting electrons in the form of an electron beam that strikes the anode surface, the electron emitting means being mounted to the annular ring,
- an annular secondary transformer winding mounted to the annular ring and centered around the central axis, the annular secondary transformer winding being connected with the electron emitting means for providing a filament current thereto;
- an annular primary transformer winding mounted to the toroidal housing adjacent the annular secondary transformer winding such that electrical current is selectively transferred therebetween;
- a means for rotating the annular ring within the evacuated interior of the toroidal housing.
- 8. An x-ray generator comprising:
- a generally toroidal housing having an evacuated interior;
- an annular anode surface mounted in the toroidal housing interior, the anode surface being in thermal communication with a cooling fluid passage such that cooling fluid can be circulated contiguous to the anode surface for removing heat;
- a cathode assembly mounted on an annular ring rotatably disposed within the toroidal housing including:
- a means for emitting electrons to form an electron beam that strikes the anode surface,
- a supporting means mounted to the annular ring adjacent the electron emitting means, the supporting means supporting at least one of an off-focal radiation collimator means and a filter means for filtering the x-ray beam, the supporting means supporting the collimator means and the filter means closely adjacent the anode means such that the filter means and the collimating means rotate with the electron beam;
- a means for rotating the annular ring such that the electron beam rotates to at least a multiplicity of points around the anode surface.
- 9. An x-ray generator comprising:
- a generally toroidal housing constructed primarily of metal, the housing having an evacuated interior;
- an annular metal anode surface mounted in the toroidal housing interior in electrical communication therewith such that the anode surface and the toroidal housing are in substantial electrical potential equilibrium with each other, the anode surface being in thermal communication with a cooling fluid passage such that the cooling fluid can be circulated contiguous to the anode surface for removing heat;
- a cathode assembly rotatably received in the evacuated interior of the toroidal housing, the cathode assembly including a cathode cup which emits electrons to form an electron beam that strikes the anode surface in response to receiving a filament current;
- a means for establishing a large potential difference between the cathode cup and the anode surface;
- an isolation transformer mounted to the cathode assembly, the isolation transformer including a secondary winding connected with the cathode cup and maintained substantially at the potential thereof and a primary winding which is maintained substantially at the potential of the housing, the primary winding being connected with a means for transferring heating current from the toroidal housing to the rotating cathode assembly;
- a means for rotating the cathode assembly within the evacuated interior of the generally toroidal housing.
- 10. The x-ray generator as set forth in claim 9 wherein the cathode assembly includes an annular ring, at least a portion of which is conductive, the electrically conductive portion of the annular ring being electrically isolated from the electron emitting means and further including a means for holding the conductive annular ring portion at the same potential as the housing.
- 11. The x-ray generator as set forth in claim 10 wherein the means for holding the conductive annular ring portion at the same potential as the housing includes a filament which is heated to boil off electrons which are conducted to the housing.
- 12. An x-ray tube comprising:
- a generally toroidal housing having an evacuated interior;
- an annular anode surface mounted in the toroidal housing interior, the anode surface being in thermal communication with a cooling fluid passage such that cooling fluid can be circulated contiguous to the anode surface for removing heat;
- a cathode assembly including:
- an annular ring rotatably disposed within the toroidal housing,
- a plurality of electron emitting means for emitting electrons to form an electron beam that strikes the anode surface, the electron emitting means being supported by the annular ring;
- a coupling means for selectively coupling the electron emitting means with an exterior current supply; and,
- a switching means supported by the annular ring for selectively switching supplied current among the electron emitting means;
- a means for rotating the annular ring.
- 13. The x-ray tube as set forth in claim 12 wherein the switching means includes a plurality of magnetically controlled switches which are mounted for rotation with the annular ring and a plurality of annular electromagnets mounted to the housing, each annular electrode magnet being disposed closely adjacent to a path of rotation of one of the magnetically controlled switches for selectively supplying a controlling magnetic field thereto.
- 14. An x-ray generator comprising:
- a generally toroidal housing constructed primarily of metal, the housing having an evacuated interior;
- an annular metal anode surface mounted in the toroidal housing interior in electrical communication therewith such that the anode surface and the toroidal housing are in substantial electrical potential equilibrium with each other, the anode surface being in thermal communication with a cooling fluid passage such that the cooling fluid can be circulated contiguous to the anode surface for removing heat;
- a cathode assembly including:
- an annular ring rotatably received in the evacuated interior of the toroidal housing, the rotatable ring including an electrically conductive portion and an electrically insulating portion,
- a cathode cup means for emitting electrons to form an electron beam that strikes the anode surface, the cathode cup means being mounted to the electrically conductive portion of the annular ring such that the electrically conductive portion and the cathode cup means are substantially in electrical potential equilibrium,
- a magnetic levitation bearing means mounted to the electrically insulating portion of the annular ring and to the toroidal housing such that the magnetic levitation bearing means and the toroidal housing are maintained substantially in electrical equilibrium with each other;
- a means for maintaining a large electrical potential difference between the cathode cup and the toroidal housing;
- a means for rotating the annular ring within the evacuated interior of the toroidal housing.
- 15. An x-ray generator comprising:
- a generally toroidal housing having an evacuated interior;
- an annular anode surface mounted in the toroidal housing interior, the anode surface being in thermal communication with a cooling fluid passage such that cooling fluid can be circulated contiguous to the anode surface for removing heat;
- a cathode assembly including:
- an annular ring rotatably received in the evacuated interior of the housing;
- a means for emitting electrons to form an electron beam that strikes the anode surface the electron emitting means being mounted to the annular ring;
- a high voltage biasing means for biasing the cathode assembly to a high negative voltage relative to the housing, the high voltage biasing means including at least one hot cathode supported by the housing and a partially toroidal electron receiving plate at least partially encompassing the hot cathode and supported by the annular ring such that the toroidal plate remains closely adjacent to the hot cathode as the annular ring rotates;
- a means for rotating the annular ring around the evacuated interior of the housing.
- 16. The x-ray generator as set forth in claim 15 further including a grid between the hot cathode and the receiving plate.
- 17. The x-ray generator as set forth in claim 15 wherein the high voltage biasing means includes a means which is biased to the high voltage, the high voltage biased means being electrically connected with the cathode assembly; and further including an electrical insulation means for insulating the high voltage biased means, the cathode, and an electrical connection therebetween from other portions of the annular ring.
- 18. The x-ray generator as set forth in claim 17 wherein the cathode assembly includes a cathode cup and further including a quick connect coupling for electrically and mechanically connecting the cathode cup and the electrical connection.
- 19. The x-ray generator as set forth in claim 17 further including:
- a secondary winding extending around at least a portion of the insulation means, the secondary winding being connected at one end with the electrical connection, and at its other end with the cathode assembly;
- a second electrical insulation means surrounding the secondary winding;
- a primary winding surrounding the second insulation means which surrounds the secondary winding, whereby an electrical isolation transformer is defined.
- 20. The x-ray generator as set forth in claim 19 wherein the primary winding is connected with a means for controlling current flow through the cathode assembly.
- 21. An x-ray tube comprising:
- a generally toroidal housing having an evacuated interior;
- an annular anode surface mounted in the toroidal housing interior, the anode surface being in thermal communication with a cooling fluid passage such that cooling fluid can be circulated contiguous to the anode surface for removing heat;
- a cathode assembly disposed within the toroidal housing including:
- an annular ring rotatably disposed within the housing,
- a means for emitting electrons to form an electron beam that strikes the anode surface;
- a means for rotating the annular ring within the toroidal housing;
- a position encoder for providing an encoded signal indicative of an angular position of the annular ring relative to the housing.
- 22. An x-ray tube comprising:
- a generally toroidal housing having an evacuated interior;
- an annular anode surface mounted in the toroidal housing interior, the anode surface being in thermal communication with a cooling fluid passage such that cooling fluid can be circulated contiguous to the anode surface for removing heat;
- a cathode assembly including;
- a means for emitting electrons to form an electron beam that strikes the anode surface, the electron emitting means rotatably disposed within the toroidal housing,
- a means for supporting at least one of a collimator and a filter mounted adjacent the electron emitting means for rotation therewith;
- a means for rotating the electron emitting means within the toroidal housing.
- 23. An x-ray tube comprising:
- a generally toroidal housing having an evacuated interior;
- a first annular anode surface mounted in the toroidal housing interior, the first anode surface being in thermal communication with a first cooling fluid passage such that cooling fluid can be circulated contiguous to the first anode surface for removing heat;
- a second anode surface mounted in the toroidal housing interior in thermal communication with a second cooling fluid passage;
- a cathode assembly disposed within the toroidal housing including:
- a first means for emitting electrons to form a first electron beam that strikes the first anode surface;
- a second means for emitting electrons mounted on the cathode assembly for selectively forming a second electron beam which strikes the second anode surface;
- a means for moving the first and second electron beams to a multiplicity of points around the first and second anode surfaces.
- 24. The X-ray tube as set forth in claim 23 wherein the first and second anode surfaces are concentric circular annuli of different radius.
- 25. The x-ray tube as set forth in claim 23 further including:
- a first filter and collimator assembly mounted to the cathode assembly and disposed adjacent the first anode surface;
- a second filter and collimator assembly mounted to the cathode assembly adjacent the second anode surface.
Parent Case Info
This application is a continuation-in-part of U.S. patent application Ser. Nos. 07/817,294 pending 07/817,295 now U.S. Pat. No. 5,200,985 and 07/817,296; all filed on Jan. 6, 1992.
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Continuation in Parts (1)
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Number |
Date |
Country |
Parent |
817294 |
Jan 1992 |
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