US1977275A

US1977275A - X-ray tube

Info

Publication number: US1977275A
Application number: US435581A
Authority: US
Inventors: Holst Gilles; Bouwers Albert
Original assignee: Philips Gloeilampenfabrieken NV
Current assignee: Koninklijke Philips NV
Priority date: 1927-01-18
Filing date: 1930-03-13
Publication date: 1934-10-16
Anticipated expiration: 1951-10-16
Also published as: DE559089C; GB286436A; CH124857A; BE368929A; NL31411C; FR38180E; GB344692A; BE372145A; FR633598A; NL24781C; CH148896A; DK44675C; DE599029C; US1893759A; BE341624A; AT138948B; DE567674C

Description

Patented Oct. 16, 1934 Gilles noise and Albert Bouwers, Eindhoven, Y Netherlandaassignors to N. V. -Philips Gloeilampenfabrreken Applicationy March4 `13,

1930, Serial N0. 435,581

In the Netherlands April 19, 1929 17 claims.

This invention relates tol an improvement ifnpr modification of vacuumH chambers, generally of the type comprising X'raytubes with rotary anticathode `as descrbedand claimedu in application il senNo. V186,522 filed Aprn 25, 1927, new Patent No. 1,893,759. f

` Tubes arranged on theprinciplextherein described have the advantage that the focal spot is not formed at the same point of the anticathode 7 10 for the` entire duration 'of' the load, but shifts constantly. Thus, the heating of the `anticathodes mirror ortarget isnot concentrated on aV dente'point but is distributed over a large surface area which permits the load'to be' of 15 greater intensity or of longer duration.

The arrangement of a rotary part within va space, having as high ajvacuum as doesprevail, for instance, in X-ray tubes, entails great diniculty. According to the above patent, the rotation is obtained by the use'of an-ant'icathode con- `stituting the rotor of `an electric motor and, in the form of construction (described in the said "patent, the rotor is journalled on `a pair of ballbearings. vThis form of construction has, how- 2'5 ever, been found to present` disadvantages.

The various metal parts arranged withinfthe tube must be substantially deprivedjof occluded gases. The driving off ofthe occludedgas'es is effected by heating these parts to a very Vhigh temperature. Such heating is,- however, injurious to the ball bearings on which the rotary part revolves. Furthermore, the heating of the device lduring its operation causes the rotation to'take -place less evenly andless lightly than might be j expected when using ballv bearings.

Ithas now been found that morev favorable results areobtained if, instead of using ball bearings "for the support of the anticathodic body, one or more slide-blocks are used, in which case an ,40' apertured bearing-disk secured to 'the `rotor surrounds a stationarvmember which member has a smaller coefficient of expansion and, preferably, `a greaterhardness than `the bearing=disk- A suitable disk for this purposeconsists of a copper- S llgraphitey alloycontfainingv about 1% of carbon.

The content ofcarbonmay vary between -about 0.5 and A3%. *The material on whichfthis disk `bears ispreferably tungsten, molybdenum, or 'a metalof similar hardness. Itisrpreferable that,

` :150 1ofthe Vsurfaces slidinglinconta'ct with each other,

thesurface of the harder material extendsbeyond Atheother. Thereby it is preventedthat, by wear, the harder material grinds grooves intothe softer :material which mighti hinder an I easy rotation.

'Pf-1a order that the' invention may tf-eieany (Cl.` Z-35) l understood and readily carried into effect one form of construction of a vacuum chamber acccrdingto the invention, represented by an X-ray tube, will be described more fully with reference to the accompanying drawing, in which;

f Figure 1 is a partly sectionized side view of an YX-ray tube according to the invention.

Figure v2 is a sectional side View, on an enlarged scale, of the anticathode of the tube.

In the two figures, like parts are designated by similar reference numerals.

Referring to Figure 1, the wall of the tubel has two glass parts 1-1 and a cylindrical metal part 3,r preferably of ferrochrorne, sealed between the glass parts. The glassparts 1 and 1 are sur- 76 rounded by renvelopes 2 2 consisting of an insulating material which is hardly transparent to X-rays; The cylindriealmetal part 3 comprises a window 4 which allows active X-ra-ys to emerge. The tube has an incandescent cathode 5 arranged 75 within a metal receptacle 6 comprising an aperture 9 which allows the electrons emitted by the incandescent cathode to pass to an anticathode 3. The two ends of the incandescent cathode are connected to contact pins 7; one by means of a 80 pole wire, the other through the metal receptacle 6 (not shown). The lead wires for the power supply to the cathode may be connected to the Vsaidcontact pins.

Ihe cathode rays are concentrated on a small 85 part of the end surface of the anticathode Sby the focussing device 6.

'The anticathode 8 is adapted to rotate within the X-ray tubeand for this purpose it constitutes the rotor ofan electric motor andis pivoted to a stationary shaft; This shaft is formed of a spindle 10 anda sleeve 12' clamped around it. Thespindle 10 is integral with'a member 11 hermetically sealed to the glass wall 1 of the tube.

rlihe `member 11 preferably consists of ferroy95 chrome and is connected to a connecting member 2 0. The anticathode has a sheath 13 formed of good conducting material, preferably of copper, which surrounds a cylinder 14 of metal of high permeability, such as soft iron.

The tube is surrounded bythe stator 15 of the motor. Thejlatter is secured to ahousing 16 which niechanicallyand electrically connects the magnet system to the metal part Bof theX-ray tube. The stator '15 carries magnet windings 17, 105 which may be connected' to a `supply circuit .of polyphasealternatng current or, when means to Vestablish a phase difference are provided, to an ordinary source of alternating current. .'Thus, lthe anticathode 8, as the rotor ofan asynchro` li() given a rotary 21 and 22. The sliding surfaces of the member 12 extend beyond those of the disks 21 and 22.l Thus the latter have an even wear and the harder material does not grind in them grooves which in course of time are injurious to the proper working. In the alloy of which the metals'21 and '22' consist, the graphite provides for lubrication which ensures a very light and noiseless running, even after long use. i

It is, of course, obvious that the invention, once disclosed, has-numerous applications in vacuum chamber practice, even where a space discharge does not occur. Accordingly, it is vint ended 'that the invention be limited only by the scope of the appended claims.

1. As part of a vacuum tube, a stationary shaft, a hollow anode concentric with and encircling the said shaft, and rotatable thereabout, at least one bearing member on the said anode cooperating with thesaid shaft, the shaft having a surface formed of harder material than said member.

2. As'part of a vacuum tube, a stationary shaft, a hollow anode concentric with and encircling the said' shaft, and rotatable -thereabout at least 'one bearing memberl on the said anode cooperating with the said shaft, the shaft having .a surface formed of material of lower coefficient-of expansion than the said member.

3. As part of a'vacuurn tube, a stationary shaft, a hollow anode concentric with and encircling the said stationary shaft and rotatable thereabout, and atleast one bearing member on the anodeand cooperating with the said shaft, the

shaft having a surface formed of harder material than the said member, and the bearing member material. I y

4. As part of a vacuum tube, a stationary'shaft, a hollow anode concentric with:and encircling the said stationary shaft andV rotatable thereabout, and at least one bearing member on Vth'e yanode and cooperating with the said shaft,l the'V 1 shaft having a surface formed of harder material than the said'member, and the bearing member `-beingformed ofan alloy of copper and carbon.l

5. As part of a vacuum tube, a stationary shaft,

` a hollow anode concentricwith and encircling the' said 'stationary shaft and rotatable thereabout, and at least one Vbearing member on Vthe anode and cooperating with the said shaft, the shaft having a surface formed of harder material than the said member, and thev bearing member being formed of an alloy of copper and approximately 0.5 to 3% carbon.

6. As part of a vacuum tube, a stationary shaft,

"a hollow'anode concentric with and-encircling `the said stationary shaft about, and at least one bearing member on the and rotatable thereanode and cooperating with thesaid` shaft, .fthe shaft having afsurface formed of harder material than the said member, and the bearing meinber being formed of an alloy containing Vapproximately 1% carbon. ,A 7. As part of a vacuum tube,-a stationaryshaft,

yshaft having a surface formed of material harder harder thanand having a lower coeflicient of ex- -aholl'owanode concentric with and encircling formedof harder material than the said memabove V.the said shaft limitingthe longitudinal movement of the bearing member and the anode securedtheretO, the

shaft, ae'hlollow anode vcircling 'the said stationary shaft and rotatable vsaid shaft having a material :thanthe saidbearing members, andthe thef 'saidn shaft and adaptedto substantially'abut gthe inner faces of the said Vbearing `membersfrto y limit the longitudinal movementthereof, the said a hollow anode concentric with and encircling the said stationary shaft, and rotatable thereabout, and at least one bearing member on the said anode and cooperating with the said shaft, the

than and having a lower coeflicient of expansion than Vthat from which the said bearing member isformed.'

8'. As part of a vacuum tube, a stationary shaft, a hollow anode concentric with and encircling the said stationary shaft, and rotatable thereabout, and at least one bearing member on the said anode and cooperating with the said shaft, the shaft having a surface formed of material pansionthan that from which the said bearing member-is formed, the said bearing member being formed of `a self-lubricating alloy.

9. As part of a vacuum tube, a stationary shaft,

,the said. vshaft and rotatable thereabout, landat leastlone bearing member on theanode cooperating With'and bearing against the said shaft, the said shaft extending outwardly beyond the said bearing member and its surface being formed i of harder material than the said member.

10. As part Yof a Vvacuum tube,` a stationary shaft, a hollow anode concentric with and encircling the said stationary shaft, and a plurality of bearing members on the said anode and co-l operating with `and bearing against the said shaft, the said shaft extending outwardly beyond the said bearing members and its surface being bers. e Y

11. As'part of a vacum tube, astationary shaft, a hollow anode concentric with and encircling the said stationary shaft and rotatable thereabout, lat least one bearing member on Vthe said anodeV and cooperating with and bearing against the said shaft, and an annular shoulder and bearing against and shaft having'Y a surface formed of harder mate- 7120 rial .than the said bearingmember. being formed ofan alloy containing a lubricating f 12, As part of a vacuum tube, a stationary concentric with and enthereabout, twobearing members secured to the said anode and` cooperatingv with and bearing against the said shaft, two annular shoulders on .the said shaft andadapted to substantiallyv abut the'inner faces of the said bearing members to limit the longitudinal movement thereofLthef surface formed of harder said .bearing members lubricatingalloy.

13. As lpartvrof a vacuumV tube, a stationaryv shaft, a hollow anode vconcentric with and encircling Vthe said stationary shaft and rotatable thereabout, two bearing members. Vsecured, to the said, anode ,andv cooperating withv and bearing against the said'shaft, two annular shoulders on being vformed of la selfshaft vextending outwardly from Vandr'beyond the saidAVV bearing members, andhaving a surface.A`

o formed of harder material. than the said bearing members, and the'said bearing membersl being formed of itself-lubricating alloy. y

1 1. 4In a-vacuum tube, a hollow anode formed placed over a hollow core of magnetically permeable material, a target seated in the said anode, concentric, apertured disks fixed in thesaidanode, a stationary shaft about which the said disks are adapted to rotate adjacent the ends thereof, and shoulders on the said Vshaft limiting the position ofthe disks by abutment against their inner faces, the shaft having a surface formed of harder material than the said disks, and the shaft extending outwardly beyond each disk.

15. In a vacuum tube, a rotor member supported by a sliding bearing comprising a bushing which consists of an alloy of copper and graphite. secured to said member and surrounding a stationary member of lower coefficient of expansion and greater hardness than said bushing.