US1603603A - High-tension device - Google Patents

Description

Oct. 19 1926.

1,603,603 w. H. T. HOLDEN HIGH TENSION DEVICE Filed Jan. 2, 1922 FIGA- INVENTOR WILLIAM H.T.HOLDE N ATTORNEY Patented Oct. 19, 1926.

UNITED STATES PATENT OFFICE.

WILLIAM HENRY TOWNE HOLDEN, OF NEW YORK, N. Y., ASSIGNOR TO WESTING- I HOUSE LAMP COMPANY, A CORPORATION OF PENNSYLVANIA.

HIGH-{PENSION DEVICE.

lines of force of the electrical field are pre vented from passing through the walls of the envelope.

Another object of my invention is to provide a device of the character indicated in which flare-backs, corona and flash-over are obviated.

Other objects will be apparent from a reading of the following description.

Heretofore in the construction of hightension tubes, particularly those employing hot cathodes, such as X-ray tubes and rectifiers, no provision was made for preventing the lines of force of the electrical field surrounding the electrodes within the envelopes of such devices from passing through the walls thereof. Apparently, because of the passage of the lines of force through a dielectric body at an angle other than 90 and of the concentration of such lines of force when effecting such passage, and, furthermore, because of the surging of these lines back and forth under the influence of an alternating current, the dielectric is sub jected to stresses which, when the dielectric is of glass, results in the breaking-down or puncture thereof, with consequent failure of the device. The rupture of the dielectric usually occurs near the seals and at the sharp angle formed at the intersection of the intermediate ortion of the tube and the tubular extensions projecting from oppositesides of the tube. Inasmuch as these devices are very expensive, it is desirable to prevent such breakage. Another disadvantage which is present in X-ray and rectifier tubes, as at present constructed, is that occasional electrical discharges, known as corona and flashover, occur at sharp projections and along the walls of the tube, especially adjacent the points where the electrodes pass through the walls. When such discharges occur they follow. the walls of the tube and cause it to be unduly heated, a condition which results in the fracture of the envelope. In addition to the foregoing-"disadvantages of high-tension tubes as heretofore constructed, it is I also noted that gases are liberated from the electrodes, even after the greatest care has been exercised in eliminating such gases. This liberation of gas is the result of dis-, charges, or flare-backs, from the electrodes toward the point where the electrodes emerge from the glass stem. Such discharges heat upthe stem, puncture it and ewoseportions of the electrodes which have not been treated to remove the occluded gases. w

The foregoing disadvantages have been obviated by the provision of hollow conductors about the neck portions of these devices. These conductors are designed to divert the lines of force representing the electrostatic field so that they conform to the contour of the envelope, and, at the same time, remove the field from the vicinity of the seal portion of the envelope. In addition to securing the foregoing advantages, the hollow conductors also function to prevent corona and flash-over and also assist in dissipating the heat resulting from the energy liberated at the electrodes of the tube. By properly placing a shield within the envelope, the objectionable consequences of the flare-back discharges are obviated.

An embodiment of the invention is illustrated in the annexed drawings, in. which,

Fig. 1 is an elevational view-of a wellknown form of an X-ray tube showing the approximate positions of the lines of orce representing the electrostatic field surrounding the electrodes therein;

Fig. 2 is an elevational view of the device illustrated in Fig. 1, showing the metallic cover or shield applied thereto and the altered position of the lines of force representing the electrostatic field;

Figs. 3 and 4 illustrate the position of the external metallic covers with respect to bulbs having ellipsoidal and cylindrical surfaces, respectively; and

Fig. 5 shows an interior shield formed of. mesh material.

The invention comprises a pair of hollow metallic shields of conductive material positioned exteriorly 'of the bulb and adjacent the ends thereof at the point where the lead-in wires for the electrodes, or the electrodes, pass through the walls, which part is usually termed the seal of the tube. These shields are conductively connected to the electrodes, or may form parts thereof, and completely surround the same, as well as the seal portion of the tube. A surface of the shields intersects the surface of the ena continuation of the angular surface of the outer shield. The inner shield is preferably made of open-mesh material in order to facilitate its being positioned within the tube. I

Referring now to the drawings, and particularly to Fig. 1, a conventional X-ray tube is illustrated as composed of an envelo e made of a transparent material, such as g ass, havin an intermediate portion or lass bulb 6 an a pair of oppositely extendmg tubular portions 7, usually termed the neck portions of the tube. The contour of the envelope varies, but usually the curvature of the intermediate portion 6 is spherical, as in Fig. 2, although this section may have an ellipsoidal form 8 or a cylindrical form 9, such as illustrated in Figs. 3 and 4, respectively. Within the neck portions of the device are mounted, in any desired man-v ner, the lead-in wires 11, which may be connected to the electrodes 12 or form a part thereof. High, potentials are impressed upon the electrodes during the operation of the device.

In the devices heretofore constructed, due to the sharp curve 13 at the juncture of the intermediate portion and the neck portion of the tube, the lines of force representing the field surrounding the electrodes pass through the walls of the envelope at an angle other than 90. In Fig. l isillustrated a conventional form of X-ray tube showing approximately the arrangement of the lines of force representing the electrostatic field- It will be apparent from this view that these lines of force enter the walls of the envelope at an acute angle and'in passing there through are somewhat concentrated, particularly at the juncture point previously mentioned. Because of this concentration, and the angular passage of the force line through the envelope, together with the constant surging of these lines back and forth under the action of the alternating current, the dielectric substance is subjected to considerable stresses. These stresses cause the dielectric material to become strained and eventually cause its dissociation, with resultant breakage of the device, particularly at the neck portions.

In order to overcome or prevent such breakage, I propose to remove the electrostatic field from the region of the neck portion of the device by the provision of a neck portions of the device.

pair of properly formed and proportioned ollow conductors about that section of the device. In Fig. 2, a pair of shields 14., formed of a suitable conductive material, which, at the same time, will also serve to radiate the heat readily, are placed in a concentric position about the seal portions of the tube. Preferabl the shields are in the form of hollow shel s which are adapted to coinpletel enclose, and be spaced from the The shells may have their rear portions 15 connected to the electrodes while their forward walls 16 are arranged at an angle of approximately 90 with respect to the surface of the intermediate portion or bulb of the envelope. This angular arrangement is essential becauseof the contour of the electrostatic field which it is desired to secure, since the lines of force emanate at an angle of 90 from the surface of the charged body and gradually curve toward the body of different potential. lrVhere the contour of the tube is different from that illustrated in Figs. 1 and 2 and is such as shown in 3 and 4,-the right angular arrangement of the surface of the walls 16' will still obtain. The. conductive shields may be secured in any desired'manner to the electrodes, and, Where the tube employs a radiator 17 (Fig. 1) one ofthe shields may be fastened thereto. It is to be appreciated that these shields, being relatively large, also assist in dissipating the heat resulting from the energy li the electrodes of the tube.

By completely enveloping the neck portions of the tube, the electrostatic discharges known as corona and flash-over, are prevented. This results from the well-known property of a hollow conductor, in which electrostatic fields cannot exist but are confined wholly to the exterior thereof.

To aid in flexing the lines of force to lie in lines substantially parallel to the walls of the envelope, the portion of the electrodes disposed within the tube may be provided with a pair of conducting members which are preferably formed of mesh material. These conductors are affixed to, or supported by, the electrodes or lead-in wires, or'in any other convenient manner, but should be in conductive relationship with the source of potential. These interior shields may form parts of the electrodes, or the electrodes mav be so designed as to produce the desired effect. A portion of the surface of each of the interior shields is preferably arranged at an angle of 90 to the surface of the intermediate portions of the tube and should also form a continuation of the correspondingly arranged angular surface of the exterior shield. 7

It is obvious that these interior shields 18 may be formed of solid material, but it is preferable to construct them of wire mate erated at rial, such as indicated in Fig. 5, wherein a plurality of fine wires 19 ma be fastened to collars 21 and clamped to tie electrode 12. The ends of the wires are held in spaced relationship by rings or loops 22, which may be secured in place after insertion of the shield within the envelope. Whether the interior shields are formed of solid or mesh material, the occluded gases should be treated out before or after they are placed within the envelope.

In practice, it may be preferable to omit the interior shields (see Figs. 3 and 4), in which event only the lines of force exterior-1y of the envelope will be made to conform to the contour thereof. Inasmuch as the hollow conductors prevent any field being formed within the seal portion of thedevice, it is obvious that such lines will not be presvent anywhere within the interior of the en'- velope embraced by the hollow "exterior shields. As these shields extend to a point adjacent the inner ends of the electrodes, the lines of force emanating from the electrodes will be confined to the intermediate portion of the device and thus be removed from that section of the device where the breakage ordinarily occurs.

With the shields arranged as indicated in Fig. 2, the lines of force representing the electrical field will be caused approximately to parallel the walls of the intermediate pore tions of the tube. In this way, the passage of the high potential through the dielectric forming the envelope of the tube is prevented and the breakage or puncturing of the tube obviated. At the same time, the electrical. field isremoved from the neck portion of the envelope and the phenomena known as corona and flash-over obviated. The interior shields assist in conforming the lines of force to the walls of the envelope and also prevent flare-back discharges occurring within the tube as, obviously, the discharges, if any, will strike the shield and thus be prevented from attacking the stems.

Many modifications may suggest themselves to those skilled in the art, but such as come within the scope of the appended claims may be considered as part of my invention.

What is claimed is:

1. The combination with two conducting members of unlike electrical potentials disposed within a closed envelope, of means for preventing the lines of force representing the electrical field from passing through the major portion of the walls of said envelope.

2. The combination with two conducting members of unlike electrical potentials disposed within a closed envelope, of means exteriorly of said envelope for preventin the lines of force representing the electrica field surrounding said members from passrounding ing through the major portion of the walls of said envelope.

3. The combination with two conducting members of unlike electrical potentials disposed within a closed envelope, of cooperatlng means on each end of said envelope ex-' teriorly thereof for preventing the lines of force representing the electrical field stirsaid members velope. v

4. The combination withtwo conducting members of unlike electricalgpotentials disposed within a closed envelope, of means on each side of said envelope and in contact with said members for causing the lines of force representing the electrical field surrounding said members to substantially conform to the contour of said envelope.

5. The combination with two conductive members of unlike electrical potentials disposed within a closed container having in-' crating with each other to prevent the lines of 'force representing the electric field from passing through the walls of the envelope.

7. The combination with two conducting members operable at different potentials disposed within a closed envelope, of a phi",- rality of hollow conductors of greater di ameter than the envelope connected to said conducting members, said hollow conductors enclosing said conducting members and disposed exteriorly of said envelope, whereby corona and flash-overs from those portions of the envelope Within said conductor are obviated.

8. The combination with two conducting members operable at different potentials disposed within a closed envelope, of a plurality of hollow conductors of greater diameter than the envelope connected to said conducting members, at least one of said hollow conductors enclosing that portion offrom passing through a portion of the walls of said en means for preventin the lines of force representing the electrlcal field from passing through the walls of a portion of said tube comprising a pair of hollow conductors asopposed and arranged approximately at right angles to the surface of the envelope.

'11. A discharge device comprising an en: velope having a pair of electrodes therein and a conductor associated with each,of said electrodes having a portion of its surface arranged substantially at an angle of 90 to the surface of the envelope to cause the lines of force representing the electrical field to assume a position substantially parallel to i the walls of the envelope.

at least a 12. An X-ray device comprising an evacuated envelope 8. pair of spaced-apart electrodes of unlike electrical potentials, a pair of hollow conical conductingshields concentric to each electrode and connected thereto and a pair of hollow conductive shields exterior to said tube and enclosing and connected to said electrodes, said shields having ortion thereof disposed at right angles to t e walls of said tube.

13. An X-ray device comprising an evacuated envelope, a air of spaced-apart electrodes of unlike e ectrical potentials, a pair of conductive shields within said envelope, said shields being connected to said electrodes and having at least a portion thereof disposed at right angles to said envelope.

14. An X-ray dev1ce comprising an evacuated envelope, a pair of spaced-apart electrodes of unlike electrical potentials, a pair of shields composed of wire disposed within said envelope, said shields being connected to said electrodes and having at least a portion thereof disposed at right angles to said 15. In a hot-cathode device, means disposed about the neck portions thereof and spaced therefrom for removing the electrical field from that ortion of the device.

16. A hot-cat ode device comprising a sealed envelope having a spherical intermediate portion and oppositely extending tubular portions, an electrode sealed in each tubular portion and projecting within said in face area disposed exteriorly of said envelope in electrical connection with said conducting members and enclosing the same so that heat resulting from the ener y liberated at the electrodes of the tube may be dissipated and the electrostatic field removed from a position adjacent said conducting members.

18. The combination with two conducting members of unlike electrical potentials disposed within a closed envelope, of a pair of hollow shields surrounding and com letely enclosing the ends of said envelope a jacent said electrodes, each of said shields being of large surface area and having at least a portion thereof arranged at right angles to said envelope so that the lines of force representing the electric field will be made to conform to the contour of said envelope and the heat generated will be dissipated.

19. An X-ray device comprising an evacuated envelope composed of two op osed tubular neck portions and an interme iate portion of uniform contour connecting said neck portions, a pair of spaced-apart electrodes operable at unlike electric potentials within said tubular portions .and having their free extremities within said intermediate portion, and a hollow shield spaced from said neck portion and concentrically arranged with respect to each of said' electrodes adjacent the extremities thereof and connected thereto.

20. An X-ray device comprising an evacuated envelope composed of a bulb and oppositely extending arms connected thereto, a plurality of electrodes, one of which is sealed within each arm and has its extremity within said bulb, a plurality of spaced-apart hollow conductive shields completely enclosing said arms and connected to said electrodes, a hollow shield concentrically disposed adjacent the inner end of each of said electrodes and connected thereto, each of said shields having at least a portion thereof disposed at right angles to the surface of said bulb.

In testimony whereof, I have hereunto subscribed my name this 30 day of December, 1921.

WILLIAM HENRY TQWNE HOLDEN.

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