Novel Method of Reducing High Voltage Arcs in X-Ray Tubes

Abstract

A bearing assembly suitable for use in conjunction with x-ray device having a rotating target anode and electron source disposed in an evacuated enclosure. The bearing assembly includes a shaft having a rotor hub to which the anode is mounted. The shaft cooperates with front and rear bearing rings to define front and rear races, and a spacer facilitates positioning of the bearing rings. Front and rear ball sets are confined in the front and rear races, respectively. A bearing housing receives the bearing rings, spacer, front and rear ball sets, and part of the shaft. Finally, a magnet is disposed near the front bearing ring to prevent escape of foreign matter from the bearings and to prevent ingress of foreign matter to the bearings. Consequently, the magnet serves to extend the life of the bearings and to prevent foreign matter related arcing of the target anode and electron source.

1 . An x-ray device, comprising: 
 (a) an evacuated housing;    (b) an electron source and a target anode disposed within said evacuated housing, said target anode positioned to receive electrons emitted by said electron source; and    (c) a bearing assembly rotatably supporting said target anode and substantially disposed within said evacuated housing, said bearing assembly including front and rear bearing rings confining respective front and rear ball sets, and said bearing assembly further including at least one magnet located so that an open path is defined at least between said front bearing ring and said at least one magnet.    
   
   
       2 . An x-ray device, comprising: 
 (a) an evacuated housing;    (b) an electron source and a target anode disposed within said evacuated housing, said target anode positioned to receive electrons emitted by said electron source; and    (c) a bearing assembly rotatably supporting said target anode and substantially disposed within said evacuated housing, said bearing assembly including front and rear bearing rings confining respective front and rear ball sets, and said bearing assembly further including at least one magnet located so that an open path is defined at least between said front bearing ring and said at least one magnet; and    wherein said at least one magnet is interposed between said target anode and said front bearing ring.    
   
   
       3 . An x-ray device, comprising: 
 (a) an evacuated housing;    (b) an electron source and a target anode disposed within said evacuated housing, said target anode positioned so as to receive electrons emitted by said electron source; and    (c) a bearing assembly substantially disposed within said evacuated housing and rotatably supporting said target anode, said bearing assembly including: 
 (i) a shaft to which said anode is mounted, the shaft defining front and rear inner races;  
 (ii) front and rear bearing rings, the front bearing ring and the front inner race collectively comprising a front race, and the rear bearing ring and rear inner race collectively comprising a rear race;  
 (iii) a spacer interposed between said front and rear bearing rings;  
 (iv) a front ball set disposed in said front race, and a rear ball set disposed in said rear race;  
 (v) a bearing housing, said bearing housing receiving said front and rear bearing rings, said front and rear ball sets, said spacer, and a portion of said shaft; and  
 (vi) means for controlling foreign matter, said means for controlling foreign matter: 
 substantially preventing escape of foreign matter from said bearing housing; and  
 substantially preventing ingress of foreign matter to said bearing housing.  
 
   
   
   
       4 . The x-ray device as recited in  claim 3 , wherein said means for controlling foreign matter magnetically attracts and retains said at least some foreign matter present in said evacuated housing.  
   
   
       5 . The x-ray device as recited in  claim 3 , wherein said means for controlling foreign matter substantially prevents escape of foreign matter from said bearing housing.  
   
   
       6 . The x-ray device as recited in  claim 3 , wherein said means for controlling foreign matter substantially prevents ingress of foreign matter to said bearing housing.  
   
   
       7 . The x-ray device as recited in  claim 3 , wherein said means for controlling foreign matter substantially prevents arcing of said electron source and said target anode arising from foreign matter present in said evacuated enclosure.  
   
   
       8 . The x-ray device as recited in  claim 3 , wherein said means for controlling foreign matter comprises at least one magnet.  
   
   
       9 . The x-ray device as recited in  claim 8 , wherein said at least one magnet substantially comprises a rare earth alloy.  
   
   
       10 . The x-ray device as recited in  claim 9 , wherein said rare earth alloy comprises a 2-17 samarium-cobalt alloy.  
   
   
       11 . A bearing assembly, said bearing assembly comprising: 
 (a) a shaft having an integral bearing hub;    (b) front and rear bearing rings which cooperate with said shaft to define front and rear races;    (c) a spacer interposed between said front and rear bearing rings such that the spacer and front and rear bearing rings are collectively disposed in a stacked arrangement;    (d) a front ball set disposed in said front race, and a rear ball set disposed in said rear race;    (e) a bearing housing, said bearing housing receiving said front and rear bearing rings, said front and rear ball sets, said spacer, and a portion of said shaft, the front bearing ring being attached to the housing; and    (f) at least one magnet located so that an open path is defined at least between said front bearing ring and said at least one magnet.    
   
   
       12 . The bearing assembly as recited in  claim 11 , wherein said shaft includes a rotor hub, said at least one magnet being attached to said rotor hub.  
   
   
       13 . The bearing assembly as recited in  claim 11 , wherein said at least one magnet is attached to said shaft.  
   
   
       14 . The bearing assembly as recited in  claim 11 , wherein said at least one magnet is attached to said bearing housing.  
   
   
       15 . The bearing assembly as recited in  claim 11 , wherein said at least one magnet comprises a plurality of magnets equally spaced about an axis of rotation of said shaft.  
   
   
       16 . The bearing assembly as recited in  claim 11 , further comprising another magnet located so that an open path is defined at least between said rear bearing ring and said another magnet.  
   
   
       17 . The bearing assembly as recited in  claim 11 , wherein said at least one magnet comprises two halves.  
   
   
       18 . The bearing assembly as recited in  claim 17 , wherein a north pole of one of said two halves is disposed adjacent to a south pole of a remaining half.  
   
   
       19 . The x-ray device as recited in  claim 11 , wherein said at least one magnet substantially comprises a rare earth alloy.  
   
   
       20 . The x-ray device as recited in  claim 19 , wherein said rare earth alloy is selected from the group consisting of: samarium-cobalt alloys, and neodymium-iron-boron alloys.  
   
   
       21 . A method for controlling foreign matter within an evacuated housing of an x-ray device, the method comprising: 
 (a) attracting foreign matter present within the evacuated housing of the x-ray device to at least one predetermined location; and    (b) retaining said foreign matter at said at least one predetermined location.    
   
   
       22 . The method as recited in  claim 21 , wherein said attracting and retaining of foreign matter are implemented by defining a magnetic field.  
   
   
       23 . A bearing assembly, comprising: 
 a shaft that defines front and rear inner races of respective front and rear ball races, and the shaft having an integral bearing hub;    front and rear bearing rings that receive the shaft and define respective front and rear    outer races of the front and rear ball races;    at least one spacer disposed about the shaft and interposed between the front and rear bearing rings so that the front and rear bearing rings are spaced apart from each other by at least a length of the at least one spacer, the spacer and front and rear bearing rings collectively being disposed in a stacked arrangement;    a front ball set partially confined in the front ball race, and a rear ball set partially confined in the rear ball race;    a bearing housing within which the front and rear bearing rings, front and rear ball sets,    and spacer are disposed; and    means for controlling foreign matter, said means for controlling foreign matter employing a magnetic effect to prevent entry of at least some foreign matter, from a location external to the bearing assembly, into the bearing assembly.    
   
   
       24 . The bearing assembly as recited in  claim 23 , wherein the means for controlling foreign matter comprises at least one magnet located proximate the front ball race, an open path being defined between the at least one magnet and the front ball race.  
   
   
       25 . The bearing assembly as recited in  claim 24 , wherein the at least one magnet comprises a plurality of magnets.  
   
   
       26 . The bearing assembly as recited in  claim 24 , wherein the at least one magnet comprises a rare earth material.  
   
   
       27 . The bearing assembly as recited in  claim 23 , wherein the shaft includes a rotor hub located proximate the front inner race.  
   
   
       28 . The bearing assembly as recited in  claim 23 , wherein at least one portion of the bearing assembly is magnetized.