US2248795A

US2248795A - Electron tube

Info

Publication number: US2248795A
Application number: US285047A
Authority: US
Inventors: Uhlmann Wolfram
Original assignee: Standard Elektrik Lorenz AG
Current assignee: Alcatel Lucent Deutschland AG; C Lorenz AG
Priority date: 1938-07-19
Filing date: 1939-07-18
Publication date: 1941-07-08
Anticipated expiration: 1958-07-08

Description

July 8, 1941. w, UHLMANN 2,248,795

ELECTRON TUBE Filed July 18, 1939 Mayra/22 [Ml/0mm.

Patented July 8, 1941 iJNiTiZiJ ELECTRON TUBE A iplication July 18, 1939, Serial No. 285,047 In Germany July 19, 1938 2 Claims.

In electron tubes or cathode ray tubes the electrode system has heretofore been scaled as a whole into the vessel thereof. This method has the disadvantage that in the case of exchanging the cathode, which in general is of less durability than any other of the electrodes, the entire electrode system must be sealed afresh. In order to overcome this drawback the invention proposes to fix the cathode on the one hand and the assembly of the other electrodes on the other hand in dilferent portions of the vessel.

The drawing shows a diagrammatic sectional View of one embodiment of the invention. Fig. 1 is a sectional view of a side elevation of a tube constructed in accordance with my invention; Fig. 2 shows an end view of the tube.

The leads or wires I for the electrode system 2 except the cathode 3 are in an annular row fastened in a reduced portion or neck b of the vacuum vessel t. The cathode 3 is mounted in well known manner in a stem 5 sealed to a tubular extension 9 of the neck 1). Sealed to the tubular extension 9 is also the well known sealing-off or exhaust tube 6, which is fixed thereto in conjunction with the stem 5.

According to a further part of the invention the following method of manufacture is proposed. From the neck 11 a portion is cut off in a manner to form an annular surface or edge 0. Edge 0 is covered with sealing glass 11. By means of the glass 01 and of glass e provided on the leads or wires i these are provisionally sealed to the edge 0. Hereupon tube 9, one end of which carries sealing glass f, is with this end inserted in the neck 13. Finally the tube g, edge e and the wires l are sealed and blown together with the aid of the vitreous materials d, e, 1.

According to one mode of assembly the electrode system 2 may first be mounted on a sort of base plate which has a comparatively wide tube fixed in the middle thereof. This tube serves for inserting afterwards the cathode. Such base plate, carrying the electrode system 2, is then sealed into the neck b. Finally, the stem 5, in which the cathode 3 is mounted, the tubular extension 9 and the exhaust tube 6 are sealed to ether.

(Cl. {Mid-27.5)

The novel method presents the following advantages: When fixing the electrode system 2, this step of manufacture requiring the use of temperatures higher than in the case of the coated cathode, the latter is not yet within the vacuum vessel so that the diiiicult step of mounting the system 2 may be effected without regard to the heat-sensitive cathode. Also, if the seals by which the wires l are held in place prove not to be tight they may be reheated without affect ing the cathode, since this and the stem 5 are not arranged until the wires l have been sealed in position. In order to provide convenient means ior adjusting the correct distance between cathode and Wehnelt cylinder 1, the cathode may be fitted with a ceramic member D which is inserted in the cylinder l until it comes against stops E which are angular pieces made of sheet metal and welded to cylinder 1.

The sealing spot of the stem 5 is so small and so far remote from the paste layer of the cathode that this layer will not be subject to detrimental temperatures.

What is claimed is:

1. An electron tube comprising a vessel, a cathode, a stem carrying this cathode independently of other electrodes in said tube, a tubular extension formed with this stem, a plurality of electrodes supported mechanically independently of said cathode and having leads arranged in an annular row, said tubular extension being sealed to said annular row of leads, and an exhaust tube formed with said tubular extension.

2. In the manufacture of electron tubes having a vessel with a reduced end portion, the method which consists in cutting a cylindrical piece from this end portion so as to form thereon an annular edge, providing this edge with sealing glass, fixing electrode leads to this glass, sealing a tubular extension to the said annular edge and leads, and finally sealing a stem having a cathode mounted thereon together with an exhaust tube to this tubular extension.

WOLFRAM UHLMANN.