US2129387A

US2129387A - Shockproof x-ray unit

Info

Publication number: US2129387A
Application number: US750760A
Authority: US
Inventors: Slack Charles Morse
Original assignee: Westinghouse Electric and Manufacturing Co
Current assignee: CBS Corp
Priority date: 1934-10-31
Filing date: 1934-10-31
Publication date: 1938-09-06
Anticipated expiration: 1955-09-06

Description

Sept. 6, 1938. c. M. sLAcK 2,129,387

sHocKPRooF X-RAY 'UNIT I Filed ooi. 51, 1954 2 sheets-sheet 1 Illaaaa ATTORNEY 4.

Sept. 6, 1938.

c. M. sLAcK SHOGKPROOF X-RAY UNIT Filed oct. 51, 1954 ,2 sheets-sheet 2 Nw ww. mw m R n n nw ww mw NN R R R N R A ww N www LPatented Sept. 6, 1938 UNITED STATES PATENT OFFICE SHOCKPROOF X-RAY UNIT Application October 31, 1934, Serial No. 750,760

3 Claims.

My invention relates to X-ray apparatus and s has particular reference to shockproof X-ray ap- A paratus wherein the danger of accidental shocks resulting to a patient or operator are entirely eliminated.

In the prior art the most common type of such apparatus is that ofthe so-called oil immersed type wherein the X-ray tube and the high tension transformer are immersed in a cooling and insulating material and encased in a metallic casing. However, a unit of this type has several disadvantageous features among which are its weight, which makes it very unwieldy to manipulate and as the tube is immersed in oil the latter 4clt's as a filter for the X-rays emanating from the A further type of shockproof unit which obviates the objectionable features inherent in the oil immersed type is that knownV as the cable connected unit. I'his latter type consists of a metallic housing lfor the X-ray tube and the energy for operating the tube is supplied from a suitable source through grounded metallic sheathed cables. The cables are suitably secured to the metallic casing through the intermediary of appropriate connecting bushings to effectively ground the metallic housing. I'he midpoint of the high tension transformer, which latter normally is employed for the source of energy, is usually grounded thus requiring insulation between the electrode terminals of the tube and the metallic casing suil'icient to prevent spark-over at a voltage equal to one-half the maximum voltage of the source.

Because the tube in this cable connected shockproof unit operates in air it is of larger size for the same applied voltage as when operating in oil. However, the tube size may be reduced somewhat below that normally required for a tube operating in air by the provision of suitable insulation between the tube terminals and the grounded metallic casing.

Heretofore it has been customary to provide blocks or sleeves of insulating material between the cable bushings and the tube terminals which are in turn provided with suitable terminals for connecting the respective conductors of the cables to the electrode terminals of the tube. This construction is not only costly to manufacture and assemble but in addition forms numerous leakage paths between the high tension carrying parts and grounded metallic casing where corona very readily forms during operation of the tube as well as frequent spark-over due to deterioration of the insulating material by the corona effect.

It is accordingly an object of my present inven- (Cl. Z50-34) tion to provide a shockproof X-ray unit wherein the X-ray tube is of a foreshortened length than normally required for a tube operating in air at the same applied voltage and the electrical energy for energizing the same is supplied through grounded metallic sheathed cables which enter the ray proof housing and are so connected to the terminals of the X-ray tube as to reduce the spacing normally required between the tube terminals and the grounded casing.

Another object of my present invention is the provision of a cable connected shockproof unit wherein the high tension carrying cables are so connected to the metallic ray-proof housing as to effectively ground the same and are connected to the terminals of the tube in such manner as to conceal all high tension carrying parts whereby sparkover and the formation of corona is eliminated resulting in the utilization of an X-ray tube of smaller dimensions than that normally required for a tube operating in air at the same applied voltage.

Another object of my present invention is the provision of a shockproof X-ray unit wherein the high potential energy for the tube -is supplied by grounded metallic sheathed cables connected to the ray-proof metallic housing and the X-ray tube terminals in such manner as to ground the housing and form a support for the tube as well as sufficiently insulate the tube terminals so that the actual air gap spacing between the latter and the grounded housing may be reduced resulting in the utilization of a tube of foreshortened length for the same applied voltage as normally required when operating inair.

Another object of my present invention is the provision of a shock-proof X-ray unit wherein the overall length of the tube is considerably reduced below that normally required for a tube operating in air at the same applied voltage and provided with reentrant stems having the electrode terminals recessed therein and the high tension cables for supplying the energy for the tube are connected directly to the recessed electrode terminals to form the requisite insulation to pre-` vent spark-over and the formation of corona between these terminals and the surrounding grounded ray-proof housing.

A further object of my present invention is the provision of an X-ray tube of foreshortened length provided with reentrant stems and having its respective electrode terminals recessed therein a sufcient distance to prevent spark-over therebetween at the maximum operating voltage of the tube.

Still further objects of my present invention will become obvious to those skilled in the art by reference to the accompanying drawings where- Figure 1 is a side View, partly broken away, of a shockproof X-ray unit constructed in accordance with my present invention,

Fig. 2 is a sectional View taken on the line II--II of Fig. 1,

Fig. 3 is a sectional View taken on the line III- III of Fig. 1,

Fig. 4 is a sectional View taken on the line IV IV of Fig. 1,

Fig. 5 is a side view in cross section and on an enlarged scale of the unit shown in Fig. l, and

Fig. 6 is a sectional fragmentary view on a still larger scale of the unit as shown in Fig. 5.

Referring now to the drawings in detail I have shown in Fig. l an X-ray tube comprising an elongated evacuated vitreous envelope 5 which is surrounded by a metallic or other suitable ray opaque housing 6 for preventing the egress of X-rays except through a Window 1 provided rin the housing. The envelope is provided with

reentrant stems

8 and 9 extending well into the envelope, as can be more readily seen in Fig. 5, with the innermost portion of the stem 8 being formed into a press Ill through which a pair of conductors II pass to the cathode electrode shown generally at I2. This latter electrode comprises the usual filament I3 which is recessed Within a focusing cup or shield I4, in turn fitting over the press portion I0 of the reentrant stem 3, and secured in place by means of a metallic ring or the like `I5. An insulated disc I6 is suitably secured to the .inner periphery of the reentrant stem il at the inner extremity thereof and is provided with a pair of recessed metallic sleeves l1 and I 9 which are connected to the filament I3 by the conductors II passing through the press and thus constitutes the cathode terminal for the tube.

An anode electrode I9 formed of a material of good electrical and thermal conductivity, such as copper or the like, and provided with the usual target 20 of refractory metal, is sealed by a feather edged copper annulus ZI to the reentrant stem portion 9 of the envelope 5. A vitreous glass sleeve 22 fused to the envelope is disposedinteriorly thereof and extends longitudinally from Well in back of the point of seal of the anode and the envelope to considerably beyond the press I6 formed in the reentrant stem 8. This sleeve is provided with constrictions 23 adjacent the anode and cathode but as the construction and operation of the same forms the basis of my copending application Serial No. 750,633, filed October 30, 1934, and forms no part per se of my present invention further detailed description herein is deemed unnecessary.

The anode I9 is provided with a longitudinal recess 24 (Fig. 6) threaded at the outer end adjacent the reentrant stem 9 and is arranged to be engaged by a metallicI member 25 provided with a recess 26 which together form an anode terminal similar to the cathode terminal comprising the disc I6 with its recessed sleeves I1 and I8. In order to circulate a cooling and insulating medium through the anode, such for example as oil, to cool the same during operation of the tube the member 25 is further provided with a metallic conduit 21 threadedly engaging Vthe same and extending Well into the recess 24, and this conduit registers with a radially extending passageway or bore 28 formed therein and made fluid tight by means of aplug 29.

A suitable tting in the form of an elbow of insulating material 30 also threadedly engages the member 25 and forms a passageway communicating with the bore 28. An inlet conduit 3I also of suitable insulating material extends from an appropriate reservoir (not shown) which in turn engages the elbow thus forming a continuous inlet passage from the reservoir to the interior of the anode with the insulation characteristic of the oil being augmented by the insulated elbow 39 and the conduit 3I so that the potential applied to the anode will not be transmitted to other parts of the unit by the cooling system.

The conduit 21 is of slightly less diameter than the recess 24 provided in the member 25 for a portion of its length and thus forms an annular passageway 32 communicating with the interior of the hollow anode recess 24. An angularly disposed passageway 33 in the member 25 communicates with the annular passage 32 and an elbow 34, similar to the elbow 30, threadedly engages the member 25 concentric With the passageway 33, said elbow being in turn engaged by an insulated return or outlet conduit leading back to the reservoir.

Accordingly during operation of the tube the cooling fluid flows from the reservoir through the inlet conduit 3l, elbow 30, passageway 28 and conduit 21 to the interior of the anode immediately in back of the target. The cool fluidafter striking the heated parts of the anode then flows through the

passageways

24, 32, and 33, respectively, and thence by means of the elbow 34 and outlet conduit35 back to the reservoir. over, due to the insulating material itself and the utilization of insulated conduits no potential stress is impressed between any other portions of the apparatus and the circulatory cooling system.

The respective ends of the envelope of the tube have insulated

caps

36 and 31 secured thereto in any suitable manner, such for example as cement 38. In order to support the tube, as Well as supply high potential energy thereto from a suitable source, such as a high voltage transformer (not shown) having the midpoint of its secondary winding grounded,`a pair 'of grounded metallic

sheathed cables

39 and 40 extend from the source to the tube. Thesecables have the metallic sheathing removed therefrom a distance corresponding to that from the outside surface of Vthe

respective end caps

36 and 31 and the cathode and anode terminals which latter are, as before stated, disposed at the innermost extremities of the respective reentrant stems 8 and` 9. A sleeve of insulating material 4I snugly fits the unsheathed portions of the respective cables and accordingly forms an integral part thereof. The sleeve 4I forming a part of 'the cable 39 is provided with a pair of pins 42 slidably engaging the recessed sleeves I1 and I8 ofthe cathode terminal with these pins being connected to the conductors of the cable 39 for the purpose of supplying cathode heating current as well as one side of the high potential energy to the cathode, and the oable'39 is held in position by a flange portion 43 of the sleeve 4I which engages the end cap 36 in any suitable manner, such as by set screws 44, thus supporting one end of the tube 5 directly upon the cable 39.

Similarly the insulating sleeve 4I, which forms an integral part of the cable is likewise provided with a pin 45, electrically connected tothe conductor in the cable 4D, said pin slidably engaging the recess 26 provided in the member More- 25 and constituting the anode terminal'. This cable dsupports the anode end of the tube in. the same manner as the cathode'end is supported by the cable 39, namely, by having Ythe flange portion of its insulating sleeve 4| secured to the end cap 31.

Accordingly the

cables

39 and 49 extend directly into the

reentrant stems

8 and 9, respectively, and the conductors .of these 'cables are not only connected directly to the electrode terminals disposed interiorly of these reentrant stems, but the tube itself is supported directly by the cables due to their integral sleeves 6| being .connected to the respective end caps 3B and 31.

Inasmuch'as these grounded high tension cables directly enter the reentrant stems and are connected to the respective recessed electrode terminals they not only conceal all high tension carrying parts but in addition form suicient insulation enabling the spacing between the grounded sheathing of the

cables

39 and 49 as well as the metallic casing 6 to be materially reduced for a tube normally operating in air at the same applied voltage. Moreover, a single leakage path is formed along which the current would have to travel to cause a spark-over, namely, between the respective electrode terminals along the integral cable sleeves 4l to the grounded sheathing or casing but, despite the fact the actual air gap spacing therebetween is materially reduced as just stated, this path is more than suiicient to prevent spark-over or the formation of corona tending to cause deterioration of the insulation. By enabling the spacing between all high tension carrying parts and ground to be materially reduced it naturally follows that the overall size of the entire unit is likewise reduced thus forming a more compact unit which may be manipulated about a patient with greater facility and is more economical to manufacture.

The metallic housing 6 surrounds the tube 5 and in order to render it ray pervious except at the window 1 the same may be provided with a layer of metal 46, of high atomic weight such as lead or the like. Each end of the casing is supported by the

respective end caps

36 and 31 of the tube. For the purpose of completing a metallic connection for the metallic housing to the grounded metallic sheathing of the

cables

39 and 40, a metallic collar 41 threadedly engages each end of the housing and .is provided with a portion 48 having a plurality of slots 49 extending longitudinally to form a good frictional contact with the metallic sheathing of the respective cables and yet allow a slight flexibility thereof.

It thus becomes obvious to those skilled in the art that I have provided a shockproof X-ray unit wherein the possibility of accidental shocks resulting to a patient or operator are entirely eliminated. The high potential energy for the tube is supplied through grounded metallic sheathed cables which are directly connected to recessed electrode terminals of the tube in such a manner that not only are all high tension carrying parts concealed but, in addition the insulation formed by the cables themselves is such as to reduce the Although I have shown and described one specific embodiment of my invention I do notfdesire to be limited thereto as various other modifications of the same may be made without departing -from the spirit and'scope of theappended claims.

:housing having an envelope` of shorter length thanv that normally required for a tube operating in air at the same applied voltage and provided with oppositely disposed reentrant stems extending a substantial distance longitudinally of said envelope, electrode terminals disposed at the innermost extremity `of said reentrant stems, and meansfor supporting said tube and for supply' ing electrical energy thereto comprising grounded metallic sheathedv cables having the metallic sheathing thereof connected to said metallic housing and provided with an unsheathed portion, an insulated sleeve snugly tting the unsheathed portion of said cables and extending directly into said reentrant stems to form a single leakage path and to increase the air-gap spacing between said electrode terminals and all grounded metallic parts to prevent the formation of corona during operation of said tube, said insulated sleeve being connected to said X-ray tube and said housing to form a support therefor, and said insulated sleeves having terminals connected to said cables and slidably engaging the electrode terminals disposed at the innermost extremity of said reentrant stems.

2. A shockproof X-ray apparatus comprising an X-ray tube having an envelope of shorter length than that normally required for ar tube operating in air at the same applied voltage and provided with oppositely disposed hollow reentrant stems extending a substantial distance longitudinally of said envelope, electrode terminals disposed at the innermost extremity of said reentrant stems, a metallic X-ray opaque housing supported by said tube and spaced relative to said electrode terminals a distance which is normally insufficient to prevent spark-over or the formation of corona therebetween during operation of said tube, grounded metallic sheathed cables for supplying electrical energy to said X-ray tube and for supporting said tube and housing as a unit, said cables having the metallic sheathing thereof connected to said housing to ground the latter and provided with an unsheathed portion, an insulating sleeve snugly fitting the unsheathed portion of said cables and extending directly into said reentrant stems to form a single lleakage path and to increase the air-gapspacing between said electrode terminals and all grounded metallic parts to prevent the formation of corona during operation of said tube, said insulating sleeve being provided with a flange portion secured to said tube and contacting said housing whereby said X-ray tube and housing are supported as a unit by said cables, and said insulated sleeves having terminals connected to said cables and slidably engaging the electrode terminals disposed at the innermost extremity of said reentrant stems.

3. A shockproof X-ray apparatus comprising an X-ray tube having an envelope of shorter length than that normally required for a tube operating in air at the same applied voltage and provided with oppositely disposed hollow cylindrical reentrant `stems extending a substantial distance longitudinally of said envelope, an X-ray opaque housing surrounding said X-ray tube and in Vcontact-,with a portionziofsaiditube to x the position thereof within-saidhousing and provided `.with an X-ray pervio-us windowvrinrsaid housing in lalignment with the ray projecting portion of said 'X-'ray tube, electrode terminals disposed at the innermost extremity of said reentrant stems `and spacedfrom said housing a distance normally insufcient `to prevent spark-over therebetween `at the operating voltage of said tube, grounded metallic sheathed cables for supplying electrical energy to said X-ray tube and having an unsheathed portio-n, a metallic iiange carried by the metallic sheathed portion of said cables and connected .to said housing to ground the latter, an insulating sleeve snugly fitting the unsheathed l portion of said cablesand extending directly into said reentrant stems to form a single lleakage path Vand to increase the air-gap spacing between said electrode terminals and all grounded metallic parts to prevent spark-over or the formation I;

Vreentrant stems.

vClif-IARI'JES MORSE SLACK.