US2459284A - Device comprising a current converting tube - Google Patents

Description

J. G. W. MULDER DEVICE COMPRISING A GURRENT CONVERIING TUBE Filed July 20, 1946 Jan. 18, 1949.

3 Sheets-Sheet 1 AGEN Jan. 18, 1949. 4 5, w, MULDER 2,459,284

DEVIC E COMPRISING A CURRENT CONVERTING TUBE Filed July 20, 1946 3 Sheets-Sheef 2 AGENT Jan. 18, 1949. w MULDER 2 459,284

DEVICE COMPRISING A CURRENT CONVERTING TUBE Filed July 20 1946 3 Sheets-Sheet 5 AGENT Patented Jan. 18, 1949 DEVICE COMPRISING A CURRENT CONVERTING TUBE Johannes Gijsbertus Wilhelm Mulder, Eindhoven, Netherlancls, assignor to Hartford National Bank and Trust Company, Hartford, Conn., as

trustee Applieation July 20, 1946, Serial N0. 685,208 In the Netherlands J anuary 30, 1943 3 Claims.

This invention relates to a device comprising a current converoing tube having a filling of gas 01 of vapour er of both, in Which a cathodescreen is provided between the cathode and one or more anode.

These tubes often have the dravvback that the first ignition voltage required when placing the tube into service, largely depends on the temperature. When, for instance, just afcer the operation the tube is practically still at its operating temperature, the first ignition voltage required on operating the tube anew is very high. When as a result of screens placed between the cathode and the anode the discharge has to follow complicated paths the requirement of an increased ignition voltage in the case of a high temperature f the tube is particularly manifest.

Tubes that are so constructed as to be free from arcing back ab the full operating voltage and at every cathode temperature 1ower than the normal (Application for a. patent Serial N0. 731,289, fi1ed February 27, 1947, now Patent 2452861 issued November 2, 1948) switched on simultaneously With the heating current.

lt is a1ready known to connect a screen, which is placed between cathode and anode, to one of he anodes through a resistance. This, however, has the dravvback of the full voltage being set up between this screen and the cahode in the negative phase, which may involve a very streng glowing current between these electrodes.

The present invention purports to eure these drawbacks by connecting the cathode screen of the tube so a potentiometer or voltage-divider connected between the cathode and one of the anodes. The current from the cathode to the screen ionizes the gas at a comparatively W voltage which depends on the filling of the taube. Once the curre-nt from the cathode to the screen has ionized ehe gas medium, charge carriers readi1y enter the range of the anode fie1d in substantia1 quantity. In practice the paths of the gaseous medium so the screen and anode are ionized simultaneously. The choice of the point of a voltage-divider, where the ca.thode screen is connected, determines the anode voltage at Which ionization occurs. Of course, the resistance 01 the voltage-divider between the anode and. the screen should not be too 10W in order 170 .prevent an unduiy strong glow discharge between cathode and screen in the negative phase.

Although, once the taube gas medium has ionized anal conveys a 1ittle current, re-ignition takes place very easily tubes having two and more anodes suffer from the drawback that the comdiions of re-ignition are not the same for all anodes, due 130 the fact that the cathode screen is connected between one of the anodes terminals anc1 the cathode. In this case 113 is particu larly advantageous to connecb a certain number of parts of the cathode screen corresponding so i-he number of anodes to the Voltag'e divided con nected between tne cathode and each anode.

It is particularly advantageous t0 use the in" vention in tubes for more than volts effective anode voltage anal et least 10 amperes rec'cified current, in which the screens between the cathode and the anodes are provided in such a manner that at the ful1 operating voltage the tube does not exhibit, arcing back ab every cathode temperature lower than Ehe normal.

In a special form of construction of these tubes the cathode screen or parts thereof are provided With holes on the side facing the one or more anodes, which holes do not serve for the passa.ge of the main discharge anti therefore de not amount to more than 5% 0f the a.perture distant for the last-mentioned discharge, in such a manner that particles disintegrating from the cathode cannot find their way to the anodes. By providing the ignition holes it ensured that charge carriers fro1'n the space With the cathode screen can easily enter the rang'e of the anode fie1d between anode and screen.

In one form of construction of a tube Which particularly satisfies the requirement of freedom from arcing back, the terminal wires of the cath ode and the one o1 more anodes a1e surrounded by tubes of ceramic material which are fused together with the W311 of the tube, whereas the anodes, except for the active front surface, are surrounded by a screen consisting of conducaive material, preferably meta1 ganze, which is secured to the tubes protecting the terminals. Betaveen the anodes is placed a screen consisting cf meta1 she-et Whose rounded front side is c1osed to ehe cathode screen, the screens being arranged about the cathode in such manner that particles, for instance of electron-emitting material, issuing from the cathode do not have a velocity compunent in the direction of the anode even after a reflection.

The current converting tubes tha are the object of the present invention often have ab the bottom side a metal hood Icr taking up the stank 0f vapor-producing material, usually mercury. Sometimes the metal hood is advantageousiy furnished With cooling ribs in order to maintain the temperature cf the mercury as 10W es possible. It is particularly simple anc1 cheap to mount ehe resistances of the voltage-divider on the cooling ribsso that the user of the t-ube need not bother aboutthese parts and may connect the tube in the same manner as tubes without cathode scr een or those where the cathode screen is internally connected to the cathode.

In order that the invention may be clearly understood anc1 readily carried inbo. efiect it will now be described more fully with reference t o the accompanying drawing, given by wa.y of example.

Figures 1a, 1b anal 1c are of vertical section, a bottom view and a horizontal section respectively of a tube having two ahndes in which the cathode screen is connected through a VON:- age-dividler to one of the anodes, Figu1es 2a 2b and 2c being respectively a, vertical anal a horizontal section of the cathode screen of the tube, in which ehe cathode screen is divided into two parts, and a bottom view of this tube.

The current converting taube shown in Figure 1 comprises a glass discharge vessel l, in which the ca.thode 2 and the anodes 3 are providecl in the same way by means cf terminal wires 4 and 5 which, through the intermediary of chrome iron hoods 6 and i are sealed in a vacuum-tight manner into Ehe ends of the tube. Bach anode is surrounded by a screen 8 partly consisting of meta1 gauge und. shielding the inactive part of the anocles. The terminal wires are surrounded by the ceramic protecting tubes 9 and H3 which the cathode.

4 divider resistances niay be given diflerent ratio so that the.ionization occurs at a dififerent anode voltae.

In Figure 2 the parts corfesponding to Figure 1 bear the same reference numeralg as in Figure l. In this case the cylindrical part of the cathode screen is divided into two parts 13' each of which corresponds to one of the two anodes and is secured to a terminal protecting tube of The two -ha1ves !3' slightly 0ver 1ap ea ch other so thas disturbances on account of electron emitting material disintegrating frm th'ecachude are avoided. The cov ar I4 of the cathode screen is separately secured to the insulating terminal tubes.

The tube inC1ud'es two inleas I5 for thetwo parts of the cathode screen and as further shown in Figure 2C two potentiometers each made up of a resistor pair 2 !22 are provided. The Voltagedivider is also constructed double and the chrome iron hood H is centrally positioned.

What I claim is:

l. A gaseous discharge current converting taube comprising a c1osed vesse1 haVing a gaseous filling, and containing a cathode, a plurality of anodes, anal a cathorle screen mounted between the cathode anal the anodes, the cathode screen havin a number of 'sections corresponding to the number of anoxies, a voltage-divider comnected between the cathode and each anode, anal meai1s connecting each cathode screen section to an intermediate point of the corresponding voltage-divider between the cathode an d the asso- I ciated anode.

through the intermediary of a connecting wire 28. The T'WO cathode inlet5 are furnished with copper connecting leads K6. Ab the bottom side of the tube is provided a chrome iron hood IT containing the stock oI mercury I8 which is protected by the screen 593 from the thermal radiation f1om he taube. The chrome iron hoocl H hag secured to it a cooling rib 20 by Which it is ensured that the temperature of the mer cury E3 on1y slig'htly exceeds room temperature. On the rib 22 are mounted two resistances 21 an. 22 jointly consticuting the voltage-divider between the eathode and. one of the anodes. The resistance 2! is directly electrically connected to the rib 22. The resistance 22 is insulated from the rib 20 by meang cf two insulating plates 23. A wire 241 connects the two resistances to the inlet 15 of the screen. The wires 26 and 27 are connected respectively tc the centre f the hQJ* ing Winding of the supply for the device com- 2. A gaseous discharge tube comprising a closecl vessel having a. gaseous filling, and containing a cathode and an anode, conducting supports f01 the cathode exaending through the wa1l ofthe Vessel and into the immer space in the vessel,

insulating tubes covering the supports to substantially the termin'als of the cathode a Cathode sCreen substanti'ally enclosing the cathode, means supporting the cathode screen onthe in sulating tubes and insulated from Ehe cathode,

prising the currentconverting tube and 110 one of the anode terminals of the taube. The nuts 25 serve to secure the resistances and the counecting wires. The, cathode screen is provided W1'th Tour ignition ho1es 29 by which the ignition of the anode current is facilitated. Besides a filling o1 mercury the tube also has a'filling of und p0tent-iometer resistance vmeans interconnecting said. anode, cathode and cathode screen for maintaining the potential of the cathode screen at a value between the potentials of the cathode and of the anode.

3. A gaseoug dscharge current converting taube comprising a closed vessel having a gaseous fi11- ing, and containing a cathode an anode and a screen fr the cathode, a metallic cup secured in v the base of the Bube td communicate With the tube, a globule of mercury in the cup heat radating ribs attached to the cup resist-ance means supported on seid ribs, und an ele ctrical couductor extending through the base of the taube With its inner end connected to thecathode screen and haVing ari external terminal fr counection a point 011 the resistance Ineans.

JOHANNES GIJSBERTUS WILHELM MULDER.

REFERENCES CITED The following references areof fecord in 1;he

file 0f this patent:

UNITED STA'I'ES PATENTS Number Na'me Date 1,038910 Von Lieben et.a1. Sept. 17, 1912 1426801 Wilson Aug. 22, 1922 1790153 Huil Jan. 27, 1931 2,-183918 Mulder Des. 19, 1939 2217185 Smith Oct. 8,1940

Certificate of Correction Patent N0. 2,459,284. January 18, 1949.

JOHANNES GIJSBERTUS WILHELM MULDER It is hereby certified that errors appear in the printed specification 0f the above numbered patent requiring correotion as follows:

Column 1, line 5, for the Word anode read anodes; line 23, after the parenthesis and before switched insert exhibz't a wem; grenzt dependency of the z'gm'tirm voltage an the temperature. I n tkese tubes the amode voltage mag; be line 40, for gas read gaseous; column 2, line 6, for divided read dz'm'aler; column 3, line 27, for gauge read gauze; line 69, f0r ionized read z'omlzes; and that the said Letters Patent should be read with these corrections therein that the same may conform to the record of the case in the Patent Ofiice.

Signed and sealed this 24th day of May, A. D. 1949.

THOMAS F. MURPHY,

Aaez'sta1zt ommz'ssz'oner of Patents.

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