US1898032A - Ionic bombardment light source - Google Patents

Description

IONIC BOMBARDMENT LGHT SOURCE Filed Dec, 4, 1950 111111111111111;rllflllllllllllzrll @miden/5f RAYMOND T. CLOUD,

Patented Feb. 21, 1933 UNITED STATES `PATENT OFFICE 0F CHICAGO, ILLINOIS, ASSIGNOB,

BY IIBNE ASSIGNMENTS, T0

or New Yoax, N. Y., .a coaroaa'rron or rome nonanbunn'r Liam' sonnen Application llled December 4, 1930. Serial No. 489,898.

GENERAL THEATERS EQUIPMENT, INC., DELAWARE These improvements relate to light sources of the kind in which an incandescent surface is produced by ionic bombardment.

y copending4 application Ser. No. 423,600, filed January 27, 1930, have illustrated and described several diierent embodiments of lamps or tubes operating on the same principle as the one herein disclosed and have in that specification described fully the principles and operations involved in such a device.

1n my copending application filed concurrently herewith as Ser. No. 499,897, Ihave described and claimed certain compositions of matter useful with the present and said embodiments of the tube.

This application is directed chiefly to a lamp construction in which there is a thir electrode useful under some conditions for starting the operation. It presents also some other constructional variations from sai first-mentioned copending application.

The prime object of the invention is to rovide a light source of high intrinsic rightness useful in recording or re reducing sound, in television, etc. Nota le features of this tube are uniformity in action and its possibilit of providing substantially a oint source o light of high actinic value. @ther objects and advantages will appear hereinafter.

lin the drawin gitudinal section tube;

Fi 2 is an enlarged fragmentary section showing arts of Fig. 1;

Fi 3 is a greatly enlarged vertical longitu inal section through the cathode proper and its carrier shell, with a fragment of a forming tool associated therewith and also in longitudinal section;

Fi 4 shows the cathode elements as in Fig. 3 with the addition of a fragment of the surrounding sleeve; and

Fig. 5 shows conventionally the output of an amplifying circuit having associate therewith a starting circuit lamp.

The device of Fig. 1 includes a base 10 in which is set the elongated glass tube 11 Figure 1 is a vertical lonthrough my improved d with the end of for the present` turned inward atthe base portion to Vform the stem 12 flattened at 13. A conductor 14 is connected to terminal 15 in the base, another conductr 16 is connected to base terminal 17, while a third conductor 18 is connected to base terminal 19. The construction thus described is according to common practice in the tube art.

Conductor 14 is connected to a conductor 20 which may approximately be a tun sten wire and which terminates in an expose end or. electrode at 21. A sleeve 22 of highly refractory material, such as ma esia, iits upon conductor 20. This electro e 21 is for startin the action of the lamp. 55

Con uctor 16 has connected to it a conductor 23 (the cathode member) which terminates in the end portion marked 24 and which is about even with electrode 21. A sleeve 25 of the refractory material, as magnesia, is placed upon this cathode conductor To conductor 18 is secured a conductor 26 which should be of tungsten or other metal that seals with the type to which in turn is secured a metallic band.- like ring 27, suitably of nickel, and which encompasses the electrodes 21 and 24 with the electrode 24 in the center of the vring formation. This ring 27 is the anode.

Turning to Fig. 3 it will be observed that the front end portion 24 of cathode conductor 23 has a hollow interior filled with material 30. The wire 23, or at least the front end portion 24, is of some metal having a high melting or fusing point such as tungsten or tantalum. I prefer tantalum for this rod or wire 23 or for the part 24 as-that metal is easier to work than tungsten, and its fusing point is very high.

In the originally-squared-oi end of rod 23, I bore the cylindrical recess 31 and fill same with the material of my said secondlymentioned copending application, packing the same therein tightly and almost flush the rod. That is to say, I pack i'n the material until the hole or recess 31 is almost filled. Then by means of a of glass used, and '75 rotating toolas 33 (Fig. 3) having a conical 4 recess 34, I swage or burnish over the side walls 24a of the electrode holder or part 24. This has the effect of further compressing the material 30 in the recess, of forming retaining means for it, and further, of reducthe size of the opening as 29 through lwnich the material 30 is exposed. I recommend a size of opening 29 ranging from six thousandths of an inch to ten thousandths of an inch in diameter.

The material 30 is thercathode proper. It has high electron-emissive properties and high heatresisting properties. In its preferred form it consists of thorium oxide (ThO,), 80% by weight, giving the mixture high heat-resisting qualities, and barium oxide (BaO), 20% by wei ht, which is the highly-emissive element. hese substances are mixed thoroughly together and maintained free of moisture as by carrying in a dessicator until the time of use. A

he barium oxide is first preliminarily heated to about seventeen hundred degrees Fahrenheit where ebullition takes place, the heating being continued until the mass becomes quiescent in the Crucible. It is then round to a line powder and mixed with t e powdered thorium oxide.

' The ring 27 is the anode. In my practice it glows at its outer margin with a typical purplish corona glow. The exposed surface at 36, however, is intensely bright and incandescent due to ionic bombardment. The corona low at the margin of anode 27 is not use by me. It may be shielded off in various ways, as by a black coating 38 applied upon the outside of the end portion of tube 1l leaving a clear axial area at 39 through which the light from the cathode surface at 36 projects.

It is pointed out in this connection that the area of the material 30 ex osed as at 36 may be only a few thousandt s of an inch in diameter to produce a highlyk eilicient light source for recording sound. I employ an exposed area of the material of about ten thousandths of an inch in diameter and thereb obtain substantially a point source of lig t. The area of exposure may be varied within considerable limits, according to the amount of light desired for a particular purpose.

It is fairly diilicult to com act the cathode material in a recess only a liew thousandths of an inch in diameter. Accordingly the cylindrical recess 3l is made more in. the nature of from twenty thousandths to twenty-iive thousandths of an inch in diameter or as may be preferred. The spinning over of the free end of the electrode reduces the openin 29 as may be desired, say to a diameter o? ten thousandths of an inch.

Using referably as low a potential as possible ihr the proper operation of the lamp the tube will ordinarily require a current flow of greater potential to get it startlamp current conductors provided the starter primary 41 has a secondary 42 one end of which is connected through conductor 43 to the anode 27. The other end of secondary 2 is connected through conductor 44 to cathode 24. This arrangement rovides a circuit for exciting the lamp duri'ng the normal operations whereby the intrinsic brightness of the cathode proper varies in proportion to the variations of current in the output of the ampliiier tube 40. Current for the lamp is sup lied by battery 46 which with resistance 47) is brldged across the condenser 48. Resistance 47 may be variously from say onethousand ohms to ten thousand ohms and is adapted to re ulate the exciting current for the tube. T e resistance 50 will be from say two hundred ohms to four hundred ohms and is preferably greater than the negative resistance of tube l1.

The starting circuit is bridged between the 43 and 44, starting with conductors 51 andv 52. Resistance 53 may be of the order of about ten thousand ohms. Conductor 54 leading from resistance 53 leads to a Contact 55 which is shown contacting switch leaf 56 from which conductor 57 leads to plate 58 of condenser 59. The effect therefore is to charge plate 58 from line 43.

Conductor 52 leads to contact 60 shown as being in contact with switch leaf 6l connected by wire 62 to plate 63 of condenser 59, thus charging plate 63 from line 44.

his arrangement provides that when plug 65 is in the open position, as shown, the current bridged across the lamp-exciting circuit is charging the plates of condenser 59. Now when plug 65 is moved forward leaf 56 makes contact with contact 66 connected by wire 66a to wire 52, and leaf l'makes contact with contact 67, the latter being connected by a wire 68 to a resistance 69 of about two thousand through wire 70 to electrode 2l.

It will thus be seen that when the plug 65 is moved to spread the leaves 56 and 61 condenser plate 63 is connected to electrode 2l while condenser plate 58 is connected to cathode 24. Under these conditions a discharge takes place between starting electrode 21 and cathode 24. The ensuing ionization instantly starts the o eration of the tube. When the operator esires to start he merely touches a switch button repreohms, and thence 'filled with an inert gas such sented by plu 65 to discharge condenser 59.

Resistance g2 (of about twenty thousand ohms) and resistance 7 3 (of about ten thousand ohms) connecting lines 43 and 44 respectively with Wire maintains the starting electrode 21 at positive potential wherenegative swings of the signalcarrying current, should the lamp go out the operation Will automatically re-start. After the lamp is initially started and gets heated it will thus automatically re-start when temporarily put out. lt is only when the lamp is cold that the `starting feature is used.

rihe tube 11 is to bey considered as being as nitrogen, argon, helium, etc., at some low pressure. in my practice Withl the particular form of lamp illustrated herein I employ nitrogen gas at a pressure of about forty millimeters of mercury.

l claim:

l. in an ionic bombardment incandescent light source device of the character described, the combination of an electrode comprising a holder for a cathode proper, said holder having a recess therein, a cathode proper comprising a material of substantially high ion-emissive properties and high heat-resisting properties and being in finely divided forni tightly packed in said recess, and an anode electrode, said electrodes being in a receptacle having a clear space for light at a place opposite said recess, said receptacle containing inert gas.

2. ln an ionic bombardment light source device of the character described, the conibination of an electrode comprising a holder tor a cathode proper, said holder having a recess therein, a cathode proper comprising a material of substantially high ionemissive properties and high heat-resisting properties and being in finelyl divided form tightly packed in said recess, and an anode electrode in the form of a ring surrounding the axis of said recess and being, adjacent to said cathode proper, said electrodes being in a receptacle having a clear space for light at a place opposite the cathode proper, said receptacle containing inert gas.

3. ln an ionic bombardment light source device of the character described, the combinaton of an electrode comprising a holder for a cathode proper, sai holder havin y a 2P recess therein, a cathode proper comprising a material of substantially high ion-emissive properties and high by on deeply heat-resisting roperties and being in finely divided form tightly packed in said recess, an anode electrode, and a third electrode adjacent to the cathode for starting the operation of the device, said electrodes being havin a clear space for light at a place opposite said recess, said receptacle containing inert gas.

4. In an ionic bombardment light source electrode, and a third in a receptacle device of the character described, the combination of a cathode` roper element comprising a material of su stantially high ionemissive properties and high heat-resisting properties and being in kti htly compacte form, an anode element, and a starting electrode element adjacent to said cathode proper, said elements being in a receptacle having a clear space at a place opposite sai cathode proper, said receptacle containing inert gas.

5. In an ionic bombardment light source device of' the character described, the coinbination of a cathode electrode having a small surface adapted to become incandescent under ionic bombardment, an anode electrode adjacent to said cathode and adapted to provide a spark for preliminarily heating said surface when the device is in normal position for use, sai electrodes being within a container having therein an inert gas.

6. In an ionic bombardment light source device of the character described, the combination of a cathode having a small surface adapted to become incandescent under ionic ardment, and an anode in the form of a ring about an axis of said cathode substantially at right angles to said surface.

7. In an ionic bombardment light source device of the character described, a cathode member comprising a metallic holder having high heat-resisting properties and having an open ended recess therein, with annular walls deining said recess at its open end, cathode material in said recess, sai walls being formed over upon the material and serving as a partial cover and retaining means therefor.

s RAYMOND T. CLOUD.

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