US2056953A - Discharge lamp - Google Patents

Description

Oct. 13, 1936. c. P. BRocKwAY DISCHARGE LAMP Filed Oct. 28, 1932 2 Sheets-Sheet 1 llll I I @NNUQNVV FMMWMMMIE a 0457 INVENTOR.

CARL l BRockwny BY WWW A TTORNEY Oct. 13, 1936. c. P. BROCKWAY 2,056,953

DISCHARGE LAMP 7 Filed 001?. 28, 1932 2 Sheets-Sheet 2 'jalylil INVENTOR. CARL F BROCkWAY ATTORNEY Patented Oct. 13, 1936 OFFICE DISCHARGE LADIP Carl P. Brockway, Paramus, N. J., minor to National Television Corporation, Wilmington, Del., a corporation of Delaware Application October 28, 1932, sem No. 639,973

6 Claims. (01.176-122) This invention relates to discharge lamps and particularly to that type of discharge lamp for producing modulated light.

One of the objects of the invention is to provide a discharge lamp in which a continuous ionization of the gas is maintained during the operation of the lamp. j

Another object of the invention is to provide a discharge lamp in which the discharge is prevented from being extinguished due to heavy modulations in the operating current.

Another object of the invention is to provide a discharge lamp in which the discharge is shifted from one path to another by the modulating current.

Still another object of the invention is to provide a discharge lamp with a plurality of elements so arranged that the useful discharge will occur between two of the elements while a nonuseful discharge will occur between another two.

Other objects of the invention and objects relating particularly to the method of assembling and constructing the various parts will be apparent as the description proceeds.

Several embodiments of the invention have been illustrated in the accompanying drawings, in which: I

Fig. 1 is a sectional side elevation view of a lamp illustrating one form of the invention which 30 may be preferred;

Fig. 2 is a front elevational view of the lamp of Fig. 1;

Fig. 3 is a fragmentary sectional view of the cathode of Figs. 1 and 2;

Fig. 4 is a sectional side elevational view of vention;

Fig. 5 is a front elevational view of the lamp of Fig. 4;

Fig. 6 is a sectional side elevational View of a modified form of the lamp of Fig. 1;

Fig. 7 is an enlarged sectional view of a portion of the cathode of Fig. 6;

Fig. 8 is a front elevational view of the lamp shown in Fig. 6;

Fig. 9 is a circuit diagram showing another manner of connecting the lamp of Figs. 6, 7, and 8; and 4 Fig. 10 is a side elevational view of another form of lamp embodying the invention.

Referring now more specifically to the drawings, the invention is shown in Fig. 1 as comprising an envelope in of glass or other suitable transparent material having a neck H which is fused to the usual inturned press ii for supa lamp illustrating a different form of the inporting the various elements of the device. A pair of solid cathodes l3 and I4 are mounted in approximately the center of the envelope and spaced from each other. These cathodes may be made of any suitable refractory metal such 5 as tungsten, molybdenum, tantalum, iron, or even softer metals, such as nickel and copper. As indicated, they are flat plates somewhat oval in shape and arranged parallel to each other although electrically separated. Any suitable 10 means may be used to mount the cathodes as by means of the support rod l5 which may be welded to the cathode l3 at the bottom thereof, and the support rod l6 which may be welded to the lower end of the cathode M. The sup- 15 port rods l5 and It may be sealed in the press l2 in a well known manner and lead-in wires I1 and I8 may be connected respectively to them for making the outside connection for the lamp.

The cathode l3 may have a hole 19 extending therethrough, positioned on the central line of the cathode but somewhat above the exact center thereof. In like manner the cathode l4 may have a hole 20 positioned on the central axis but below the exact center thereof so as to be out of alignment with the hole l9 and the cathode l3.

An anode 2| having a shape similar to the cathode l3 although lighter in weight and composed, if desired, of a similar metal, may be 30 mounted on a support rod 22 as by welding, and the support rod may be sealed in the press I 2 spaced from the support rod l5 as indicated. A lead-in wire 23 may be attached to the support rod 22 for making the external connection to 5 the anode 2|. At a point aligned with the hole IS in the cathode I3 I provide a somewhat smaller hole in the anode so that the hole IS in the cathode l3 may be viewed through the hole in the anode.

A second anode 25 may be positioned in like manner spaced slightly from the cathode l4. This anode is also about the same size and shape as the cathode l4, although it may be formed of somewhat lighter material, and is mounted upon 45 a support rod 26 which is sealed in the press I2. A lead-in wire 21 may be connected to the support rod 26 for making the external connection. The anode 25 may also be provided with a hole 28 which is in alignment with the hole 50 20 in the cathode it.

Both cathodes l3 and I4, and the anodes too. if desired, may be coated with a material 29, which is relatively low in electron emission so as to eliminate or cut down as far as possible the 56 electron emission from the surface of the oathode, except in the interior of the holes l9 and 20 where the material is omitted. This material may be any suitable insulating material, or if desired, the cathodes may be coated with lamp black, or otherwise carbonized, carbon having apparently the eiiect of cutting down electron emission to a minimum.

With the elements mounted as described above, the envelope may be connected to a vacuum pump and an oven placed over it to raise the temperature thereof together with the enclosed elements so as to drive out all occluded gases from the elements and envelope. When the parts have been thoroughly freed from gases in a manner well known in the art, a suitable ionizable gas may be admitted to the envelope at a relatively low pressure so as to permit a discharge forming between the anodes and cathodes when a suitable potential is applied between them. This gas may be one of the monatomic gases, such as neon, argon, helium, krypton, and xenon, or mixtures of such gases, and under certain conditions where it is desired to increase conductivity or to produce color efiects, metal vapors may be added, such as the vapors of mercury, caesium, sodium, rubidium, and the like. The pressure of the gas should be under 15 mm. of mercury and probably best results are obtained with pressure in the neighborhood of 5 mm.

If one of the cathodes and its adjacent anode are connected to a source of modulated current at a suitable voltage, it will be evident that a discharge will torm between the cathode and anode and will concentrate in the hole provided in the cathode which will then act as a crater, and this discharge can be observed through the hole in the anode which may then act as a frame to limit the size of the light source to a predetermined dimension.

I may, however, prefer to connect the lamp in a diiTerent manner as clearly indicated in Fig. 1. Here the two cathode leads I! and i8 are connected by means of wires 30 and 3| respectively to the terminals 32 and 33 of an incoming source of modulated current such as that produced by a television signal or a sound program picked up by a microphone. A wire 34 is connected to both wires 23 and 21 which form the two anode leads and is connected through a battery 35 to a neutral point of the modulated circuit by means of a resistance 36 which is placed across the wires 30 and 3| and to the center of which the negative side of the battery 35 is connected. In a typical set-up a battery voltage of 200 volts is employed to initiate the discharge between the cathode and anode with a current ranging from 60 to milliamperes.

As the incoming current fluctuates due to the modulations received, the polarity of the oathodes I3 and I4 will change, one always being more negative than the other depending on the strength of the modulation. As the two anodes 2| and 25 are connected together, their potential will be the same and hence a discharge will form between one of the anodes and whichever cathode has a more negative potential. This discharge is caused by the battery 35 which furnishes a constant source of potential and hence there will be a discharge somewhere in the lamp at all times. However, as the cathode l3, for instance, varies its potential from a low negative towards the positive side, the discharge between the anode 2| and cathode |3 will fall ofi while that between the anode 2-5 and the cathode |4 will increase. Hence, while there will always lated light although both are adaptable for use and may be used, if desired.

In Figs. 4 and 5 another modification of the invention is illustrated. Here an envelope I0 is provided with an inturned press |2 in which are sealed three support rods 42, 43, and 44. Upon the support rod 42 I position a cathode 45 which is formed of a solid plate of suitable metal having an extended portion 45 on one side and a hole or crater 41 on the other side extending into the portion 46. This cathode may be coated similarly to those described above with a coating 48 of carbon or other suitable material to cut down emission except in the crater 41. The cathode 45 and support rod 42 are so positioned that they occupy a plane spaced somewhat from the center of the lamp.

In approximately the center of the lamp I position a.small anode 49 upon the support rod 43. This anode may be semi-circular in shape, if desired, and may be formed of the same metal as the cathode 45. A shallow crater 50 is provided in the anode 49 in alignment with the crater 41 of the cathode 45, and the whole anode together with the support rod may be coated with the coating material.

A second and larger anode 5| having a shape similar to the cathode 45 may be positioned spaced slightly on the other side of the anode 49 and an opening 52 may be provided in the anode just above the upper edge of the anode 49. Leadin wires 53 and 54 may be connected respectively to support rods 42 and 43 and a battery 55 or other source of constant potential may be connected across these two wires with the positive side of the battery connected to the anode 49 and the negative side to the cathode 45. A leadin wire 56 may also be connected to the support rod 44 and anode 5| and may be connected to the terminal 51 for the incoming modulated current while the other terminal 58 of the incoming circuit may be connected by means of a wire 59 to the negative side of the battery 55.

With this construction as indicated in Fig. 4, a direct current discharge will flow between the cathode 45 and the anode 49. This discharge will be concentrated in the crater 41 of the cathode and will not be visible from the front or righthand side of Fig. 4 as it will be obscured by the anode 49. When the anode 5|, however, becomes highly positively charged due to the modulating current, the potential of which should be greater than that of the battery, the discharge will leave the anode 49 and pass over the top thereof to the anode 5| so that it may be clearly viewed through the hole 52 in the anode. There will always be a discharge in the lamp and hence there will be no necessity of building up a high starting potential for the modulated current as the discharge will jump to the anode 5| immediately the potential of the anode is higher than that of the anode 49 and instantaneous modulation of the light as viewed'through the hole 52 in the anode 5|, will, therefore, be evident.

I up the lamp of Fig. 6.

A modified form of the construction of Figs. 1 to 3, has been illustrated in Figs. 6, 7 and 8. Here an envelope I0, provided with the usual press I2, supports a single large solid'cathode 62 and a pair of anodes 63 and 64 spaced one on each side of the cathode.

The cathode may be formed of any of the metals mentioned above but is preferably somewhat thicker than either of the cathodes of Fig. 1 and may be supported on two support rods 66 which are sealed at the center of the press I 2 and which pass upwardly, one on each side of the cathode. The cathode 62 has a crater 66 in one side thereof positioned above the center of the cathode while a crater 61 in the other side of the cathode is positioned below the center, these craters taking the place of the two craters l9 and 20 in the cathodes I3 and ll of Fig. 1. The cathode 62 may be covered with a coating 68 of the material low in electron emissivity which has already been described. The anode 63 may be provided with an opening 69 in alignment with the crater 66, while the anode 66 has an opening 10 in alignment with the crater 61. The anodes 63 and 64 may be mounted respectively upon support rods H and 12 sealed in the press. A lead-in wire 18 may be connected to one of the cathode support rods 65 while lead-in wires 14 and 15 may be connected respectively to the support rods H and 12. The lamp may be provided with the gases as described above.

One way of connecting up the lamp just described is indicated in Fig. 6 where a battery 16 has its negative end connected by means of the wire 11 to the lead-in wire 13 for the cathode. while the positive side of the battery is connected by means of a wire 18 to the mid-point 19 of a resistance 80 connected across the two leads 14 and 15 which may be connected respectively to the terminals 8| and 82 of the incoming modulated current circuit.

The lamp functions similarly to that shown in Fig. 1 although opposite thereto. The cathode 62 is given a negative potential by the battery while the two anodes are connected to the modulatlng circuit so that they vary in potential in accordance with the modulations received. Whichever anode is, therefore, the more positive at the moment will receive the discharge caused by the battery. Hence there will always be a discharge in the lamp but it will flicker between the crater 66 and anode 63 and the crater 61 and anode 64. The intense discharge appearing in either of the craters 66 and 61 may be viewed in front of their respective anodes through the holes 69 and 10 respectively.

In Fig. 9 is shown another means of connecting Here the cathode 62 is connected by means of a wire 83 to an input terminal 84 of the incoming modulated circuit, while the anode 63 is connected by means of a wire 85 to the other terminal 86 of the incoming circuit. The other anode 64 is connected by means of a wire 81 to the positive side of a battery 88 while the negative side of the battery is connected by means of the wire 89 to the wire 83 connected to the cathode. Thus a constant discharge takes place between the cathode 62 and the anode 64 which tends to maintain an ionized condition of the gas within the envelope and permits the ready formation of discharge between the oathode and anode 63 and maintains it in spite of heavy modulation with long dark periods.

and 9| are connected together by a relatively long tube 92, the tube being fused to the glass bulbs at the tip ends thereof so as to form a gas-tight duct between them. The bulb 90 may be'provided with a press 93 in which is sealed a support wire 94, and an anode 95 consisting of a disc of suitable metal may be secured as by welding to the end of the rod 94. nected to the support rod. 96 and may have its other end attached to the terminal 91 of the incoming modulated current circuit.

The bulb 9| may contain a pair of electrodes 98 and 99 mounted in a spaced position upon support wires I00 and IM respectively. The support rods are sealed in the press I02 which is fused to the envelope as indicated. The electrodes 98 and 99 may be formed of any suitable metal as mentioned-above and may be circular in form with the edges thereof terminating not far from the opening of the tube 92. A lead-in wire I03 may be connected to the support rod I00 and have its other end connected to the terminal I04 forming the other terminal of the incoming modulated current circuit. Also a lead-in wire I05 may be connected to the support rod IM and may be connected to the positive side of a, battery I06 whose negative side is connected by means of the wire I01 to the wire I03, or, in other words, to the electrode 98. This puts a constant potential between the electrodes 98 and 99 with the result that a constant discharge will form in the bulb 9|. The negative side of the modulated circuit is connected by the wire I03 to the electrode 98 which therefore forms the cathode for the anode 95 and a modulated discharge will form in the tube 92. Inasmuch as the discharge between the plates 98 and 99 is continuous and constant, there will always be ionization in the bulb 9 I and hence the discharge can readily start between the electrode 98 and the anode 95, thus creating a practically instantaneous response to modulated input currents.

From the above description it will be seen that I have provided a lamp for use with modulated current in which the ionization in the lamp is maintained constant so that the discharge can start at relatively low voltages and is prevented from being extinguished due to long dark periods in the modulated circuit and current. The lamp lends itself particularly to use with television apparatus in which the modulations are extremely rapid or may also be used in connection with sound-on-film apparatus or in any other instance where modulated light is necessary or desirable.

Many modifications of the invention may be resorted to without departing from the spirit thereof, and I do not, therefore, desire to limit myself to what has been shown and described except as such limitations occur in the appended claims.

What I desire to secure by Letters Patent and claim is: I k

1. In combination, a discharge lamp comprising a pair of electrodes, means to connect a modulated circuit to said electrodes, means to. create a neutral point between said electrodes, a third electrode within said lamp, a circuit connection between the neutral point and said third electrode and means for impressing a constant potential on said circuit connection, said electrodes being so arranged that the intense discharge between said third electrode and one only of the other electrodes is observable from a given position.

2. In an apparatus of the class described, a

A lead-in wire 96 may be con- .pair of spaced electrodes, an ionizable gas sur rounding said electrodes, means to connect a source of modulated current across said electrodes, means to locate approximately the electrical center between said electrodes, a third electrode spaced between said other two electrodes, a circuit connection between said third electrode and electrical center, and means to impress a constant potential upon said circuit connection.

3. A discharge lamp comprising apair oi. closely spaced cathodes electrically separated from each other, an anode spaced from one cathode, an anode spaced from the other cathode, and an ionizable gas surrounding said cathodes and anodes, said anodes and cathodes being so arranged that the intense discharge between one only of said cathodes and one only of said anodes is visible from a given position.

4. A discharge lamp comprising a pair of flat cathodes with spaced and adjacent faces, a crater in each of said cathodes, said craters being out of alignment, an anode positioned adjacent one of said cathodes, an anode positioned adjacent the other of said cathodes, and an ionizable gas sursaid anodes having openings therein arranged in alignment with the craters oi the adjacent cathodes, and an ionizable gas surrounding said anodes and cathodes, said anodes being external to said cathodes.

6. A discharge lamp comprising a pair of flat cathodes with spaced and adjacent faces, a crater in each of said cathodes, said craters being out oi alignment, a coating of material having a low electron emission on each of said cathodes with the exception of the craters thereof, an anode positioned adjacent one of said cathodes. an

anode positioned adjacent the other of said cathodes, and an ionizable gas surrounding said anodes and cathodes, said anodes being external to said cathodes.

' CARL P. BROCKWAY.

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