X-ray tube electron sources
First Claim
1. An electron source for an X-ray scanner comprising:
- electron emitting means defining a plurality of electron source regions;
an extraction grid defining a plurality of grid regions each associated with at least a respective one of the electron source regions; and
control means arranged to control the relative electrical potential between each of the grid regions and the respective source region so that the position from which electrons are extracted from the emitting means can be moved between said source regions.
1 Assignment
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Accused Products
Abstract
An X-ray tube includes an emitter wire (18) enclosed in a suppressor(14, 16). An extraction grid comprises a number of parallel wires (20) extending perpendicular to the emitter wire, and a focusing grid comprises a number of wires (22) parallel to the grid wires (20) and spaced apart at equal spacing to the grid wires (20). The grid wire are connected by means of switches to a positive extracting potential or a negative inhibiting potential, and the switches are controlled so that at any one time a pair of adjacent grid wires (22) are connected together to form an extracting pair, which produce an electron beam. The position of the beam is moved by switching different pairs of grid wires to the extracting potential.
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Citations
60 Claims
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1. An electron source for an X-ray scanner comprising:
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electron emitting means defining a plurality of electron source regions;
an extraction grid defining a plurality of grid regions each associated with at least a respective one of the electron source regions; and
control means arranged to control the relative electrical potential between each of the grid regions and the respective source region so that the position from which electrons are extracted from the emitting means can be moved between said source regions. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 54, 55, 56, 57, 58, 59, 60)
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27. (canceled)
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38. (canceled)
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39. (canceled)
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40. (canceled)
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42. An X-ray scanner comprising:
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an X-ray source having a plurality of X-ray source points;
X-ray detection means; and
control means arranged to control the source to produce X-rays from a plurality of successive groupings of the source points and to record a reading of the detection means for each of the illuminations.
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48. An X-ray scanner comprising:
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an X-ray source comprising a linear array of source points; and
a detector array, comprising a linear arrangement of detectors, wherein the linear arrays are arranged substantially perpendicular to each other; and
control means, wherein control means is arranged to control either the source points or the detector array to operate in a plurality of successive groupings, each grouping comprising groups of different numbers of the source points or detectors, and to analyse readings from the detectors using a mathematical transform to produce a three-dimensional image of an object. - View Dependent Claims (49, 50)
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51. (canceled)
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52. (canceled)
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53. (canceled)
Specification