US2515920A - Electric discharge tube with internal condenser construction - Google Patents

Description

G. H. P. ALMA ET AL ELECTRIC DISCHARGE TUBE WITH INTERNAL Ju ly 18, 1950 CONDENSER CONSTRUCTION Filed July 2() 1946- INVENTORS GERRIT HENDRIK PETRUS ALMA KORNELIS SWIER KNOL PIETER NICOLAAS KUIPER FRITS PRAKKE MAXIMILIAAN JULIUS QTTO STRUTT ALDERT VAN DER ZIEL AGENT Patented July 18, 1950 ELECTRICDISCHARGE TUBE WITH INTER- NAL CONDENSER CONSTRUCTION Gerrit Henrik Petrus Alma, Kornelis Swier Knol, Pieter Nicolaas Kuiper, Frits Prakke, Maximiliaan Julius Otto Strutt, and Aldert van der Ziel, Eindhoven, Netherlands, assignots to Hartford National Bank and Trust Company, Hatforoi, Conn., as trustee ApplicationJuly 20, 1946, Serial No. 685,185 111 the Netheriands September 10, 1943 Sectionl, Public Law 690, August 8, 1946 Patent expires September 10, 1963 3 Claims. 01. aso-27.5)

This invention rlates toe1ectrie discharge tubes comprising builtin condensers.

It is generally knovzn to house condensers and other elements pertaining to the Circuit-arrangement, whch are usualiy loeated outside the tube, Wthn the latter, Which is advantageous, more particularly With tubes for short and ultra short waves, since in this case the connections between electrodes and circuit elements are requred to be short. I-Iowever, built-in condensers nvolve complicatons in the construction of the interior of these tubes, whiist With the use ior short and ultra short waves the actually shortconnections betvveen electrodes anci condensers frequently st11 have an excessiveiy high selfinduction.

The above-mentioned drawbacks may be obviated by using a discharge tube according to the present nvention, which tube comprises one or more condensers housed in the nterior, these condensers constitutng at the same time constructinai elements of the electrode system. By constructional elements are meant in this case bodies which are connected, either directly or indireetly, to the e1ectrodes and whch act in some way or other as supporting members, screning membeis and the 1ike. Thus, for example, use may 'be made of plate-shaped condensers consisting of a plate made of insulating material, ior ex.- amp1e mica, and coated on both sides With a silver 1ayer. Such a plate may be arranged at the top or at the bottom of the electrode system and may act at the Same time as a screening member, as a condenser and as a supporting member.

Another possble form of construction of condensers built-in in a discharge tube according to the inventon consists in that one or more supporting rode of the eleetrodes are built up from two or more than two coaxial conductors which are separated byinsulating material. The conductiVe layers constitute in this case the various coatings of the condenser; these coatings are separated by insulating material whch acts as the dielectric. The above-described rod-shaped condensers may be constructed, for example, as cirawn condensers, two or more conductors being arranged around. one another With the interposition of insulating material and being drawn out to a smaller diameter by swagng and drawng. Since the distance between these conductors may be Vel'y small, such a condenser may have a high capacity per unit of length, for example from to 100 micromicrofarads per centimeter, according to the dieleetric and the distance between the conductors. With these drawn condensers the conductors may consst of copper, nickel or simi1ar material and are separated by an intermediate layer of magnesia, titanium oxide or sirnilar insulating material.

Thus, Wh1e the consideratons of construc ton make it advantageous to utilize dscharge tubes according to the presentinventon both for longand short-wave purposes, the inventionis of particular importance for tubes operating en short and ultra-short waves, since in these appli cations the advantage of the elimination of specia1 conneotions between the condensers and the electrodesis of very greatimportance notoniy from the point of view of constructon, but als from the eleetric vewpoint Thus, for example, the invention may beadvantageouslyapplied to tubes for dec;imeter and centimeter wavesn order to increase the mutual capacity of determined electrodes and to 0btain in this way a reducton of the output demping, For what purpose -a discharge tube accordingto the invention may be used; we always have here a constructon wherein the electrodes and the circuit elementsare connected to one anotherin -the shortest possib1e manner, that is, in many cases direotly, without separate wires.

In order that the nventiorimay be c1early understood and readily carried into effect, it wiil now be explained more fully With reference to the accompanyng drawing, wherein Fig. 1 represents diagrammatically a circuitarrangement of a tube according to the invention, and

Figs. 2 and 3 show different forms of construction of such a tube.

In the figures, I designates the cathode, 2 the input control electrode, 3 the anode, whch generally consists in such tubes of two plates connected to one another by a strap, i designates a sereen grid and 5 a suppressor grid. The sereen grid 4 is capacitively coupled to the electrode 5. A tube 2 is shown enclosing these elements.

In order to obtain a symmetrical arrangement and to keep the input circuit and the output circuit separated from one another as completely as possible, the cathocle I has two supply conductors, whilst the electrodes 4 and 5 are connected or coupled to the cathode on two Sides. With decimeter and centimeter waves this arrangement is very aovantageous, since each supp1y wire acts as a self-inductance, With the arrangement according to Fig. 1 the input and the output of the tube are completely separated from one another. It is of very great importance that the condensers 6 should be connected directly to the electrode 4 and 5, with the use of connecting wres of the smallest possble length. In the form of construction according to Fig. 2 use is made of drawn condensers which act at the same time as supporting rods of the grid 5. The grid wires of this grid may be wourddirectly on the outer conductor 1 of the drawn condensers. The inner conductors 8 are connected to the sereen grd 4 through the intermediary of very short straps 9. The grds 2 and 4may be wound in the usual manner on supporting rods |4. In Fig, 2 the whole of the system is srroundd by a screening electrode I whch is connected to the cathde and ths screen is surrounded by an envelope 20.

In the form of construction according to Fig. 3 use is made of disc-shaped condensers. 'Ihey consist of an insulating plate, for example of mica or ceramc material, to both sides of which is supplied by squirting a layer of silver.

The electrodes 4 and5 are fixed in the insulating plate by means of small flanged tubes. ver layers are arranged in such a manner that The silthe one plate makes contact wth the flansed tubes of the grid 4 and leaves an open space around those of the grid 5, whereas the other silver layer is in contact wth the flanged tubes of the grid 5, but isinsulated from those of the grid 4. The flanged tubes may be provided wth tags in order to ensure a better contact wth the silver layer concerned.

In Fig. 3 the upper silver layer is in contact with the tags 13 of the electrode 4. In order to avoid excessive heating due to crculating currents during the degassing or durng operation the silver layer may exhbt a gap I2. The slver layer which is in contact with the grid 5 acts at the same time as a sereen. Such dsc-shaped condensers are preferably arranged at two ends of the electrode system, Where they replace the screens usually provded at these ponts. An

example for the usual wave lengths.

4 porated in tubes designed for other purposes, for

Furthermore, the two descrlbed forms of constructon may be combined whlst, as the case may be, other forms of condensers may be pussible.

What we claim is:

1. An electrc discharge tube comprising an electrode system ncluding a cathode, an anode, a plurality of grid elements having gricl wires and interposed between said cathode and said anode, supporting rods adjacent the said grid elements, a supporting rod. for one grid element consisting of an inner conductor, a cylindrcal insulator encrcling the said inner conductor and a metallic cylinder encrcling the cylindrical insulator constitutn the supportng rod a cylindrical condenser, the said supporting rod engaging the sad grd wres and supportng the said element at the encircling metallic cylinder thereof, and a short strap connecting the said inner conductor to an adjacent grd electrode.

2. An electrc discharge tube as claimed in claim 1 in whch a plurality of cylindrical condensers support a grd electrode, the grid electrode beng connected to the outer metallic cylinders of the said condensers, and a plurality of short straps connecting the inner conductors of the said condensers to an adjacent grid electrode.

3. An electrc discharge tube as claimed in claim 2, wherein the cylindrical condensers consist of drawn coaxial conductors, between which insulating material is provided.

GERRIT HENDRIK PETRUS ALMA. KORNELIS SWIER KNOL.

PIETER NICOLAAS KUIPER.

FRITS PRAKKE.

MAXIMILIAAN JULIUS OTTO STRUTT. ALDER'I VAN DER ZIEL.

REFERENCES CITED The ollowing references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,832,909 Lewis Nov. 24, 1931 1,879544 Scognamillo et al. Sept. 27, 1932

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