US2075202A

US2075202A - Electron discharge tube

Info

Publication number: US2075202A
Application number: US67999A
Authority: US
Inventors: Jonker Johan Lodewijk Hendrik
Original assignee: Philips Gloeilampenfabrieken NV
Current assignee: Koninklijke Philips NV
Priority date: 1934-12-12
Filing date: 1936-03-10
Publication date: 1937-03-30
Anticipated expiration: 1954-03-30

Description

ELEGTRON DISCHARGE TUBE- Filed March 1o, 195e INVEYI'R. JOHAN LODI-:WIJK HENDRIK JONKER' A TTG RNEY.

Patented Mar. 30, 1937 UNITED STATES ELECTRON DISCHARGE TUBE Johan Lodewijk Hendrik Jonker, Eindhoven,

Netherlands, assig-nor to N. V. Philips Gloeii lampenfabrieken, Eindhoven, Netherlands Application March 10, 1936, Serial No. 67,999 In the Netherlands December 12, 1934 1 Claim.

This invention relates to an electron discharge tube, more particularly to improvements in electron discharge tubes having two or more grids.

5 The applicant has found that particularly in the case of tubes comprising at least one grid wound with a varying pitch the operating'conditions in the conventional multigrid tube are not entirely satisfactory. In such tubes, for example in the case of the so-called tube with variable mu characteristic, the control grid is gener-ally wound with variable pitch, the following grids, for example the screening grid, the suppressor grid and the like being wound normally. It has been found that with this construction the most favorable conditions are not obtained, this being true for example, when the control grid has a varying pitch between wires and the grid following after it or one of the next successive grids is wound with a constant, generally fairly small pitch.

In the case Where the pitch of the conventional grids following the control grid is such as to provide the most favorable operating conditions opposite the closely spaced turns of a variable pitch grid, this pitch of the following grids would not be such as to provide the most favorable operating conditions opposite the portions of the control grid Where the turns of the control grid are more widely spaced. If, for example in a pentode, the suppressor grid is wound with a normal regular pitch, whereas the control grid has a varying pitch at the portions of the control grid where the pitch is Wide, a great number of electrons will pass through to the suppressor grid but cannot pass in an undisturbed manner` through the comparatively small pitch in the suppressor grid or in any further grid found in the path of the electrons, with the result that a high space ch-arge may build up which may cause the electric properties of the tube to be varied in an undesirable manner. The reverse may also be true. If for example the suppressor grid is made with a constant wide pitch satisfactory for the wide portions of the control grid, it may be entirely unsatisfactory for the small pitch portions of the control grid. In this connection for example, the internal resistance of tubes for special purposes may often have to have especially high values, which may be detrimentally inuenced by the above mentioned phenomena, for although in the above mentioned cases comparatively favorable conditions may be obtained for part of the grids, this may be offset by other parts of the grid so that as the final result the (Cl. Z50-27.5)

construction of the tube is not found to be the most favorable.

It is the principal object of this invention to provide an electron discharge tube of improved type which overcomes the above difficulties and can be operated under favorable conditions with respect to the path of the electrons and which has improved electric properties.

It has been found that the above difficulties can be obviated by the present invention. Thus, 10 according to the invention, in an electron discharge tube comprising two or more grids at least one of which has a varyingpitch the construction of one or more of the remaining grids in the tube is so altered as to conform with the 15 construction of the first mentioned vgrid so that the most favorable conditions are obtained in connection with the path of the electrons and the resultant electric properties of the tube.

In a preferred embodiment of the present in- 20 vention an electron discharge tube, particularly a tube h-aving a variable mu characteristic, comprises at least two grids wound with a variable pitch. This ensures that for the entire surface of such a grid the most favorable conditions 25 as regards the electric properties of the tube can be obtained.

In addition, the invention is not only applicable to those grid constructions in which the variability of their construction consists in the 30 variation of the pitch of the grid itself so that between the wires apertures of different size are obtained, but also to those grids in which the position of the side rods may bring about alterations in the path of the electrons through the 35 tube. In this case, these alterations may be largely compensated for by the side rods of one of the following grids being arranged at a given point or being given a determined diameter.

In order that the invention may be clearly 40 understood and readily carried into effect it will now be described more fully with reference to the accompanying drawing in which the single embodiment of the invention is illustrated very diagrammatically. 45

Referring to the drawing, the electron discharge tube has an electrode mount assembly comprising a cathode I, in the present case an indirectly heated cathode, of an electron discharge tube is surrounded by

grids

2, 3 and 4 50 which may be used as the control grid, the screening grid and the suppressor grid respectively, these electrodes being finally surrounded by an anode 5. It is readily apparent from the figure that the first gridhas a varying pitch 55 10 however, not essential that the pitch of the two grids should extend in exactly the same manner.

While I have indicated the preferred embodiV ments of my invention of which I am now aware and have also indicated only one specic appli- 15 cation for which my invention may be employed,V

it will be apparent that my invention by no means limited to the exact forms illustrated or the use indicated, but that many variations may be made in the particular structure used and t the purpose for which it is employed without departing from the scope of my invention as set forth in the appended claim.

I claim: Y

An electron discharge tube having an electrode mount assembly comprisingia'cathode andanode, and at least .threesuccessive grids between said cathode and anode, the grid next to said cathode lhaving a variable pitch and the grid next to the anode having a pitch which conforms substantially to the pitch of the grid next to the cathode,

the wires of the last two mentioned grids being in substantial alignment.

JOHAN LODEWIJK HENDRIK JONKER.