US2264081A - Gaseous discharge lamp - Google Patents

Description

K. JOST ETAL GA'sEoUs DISCHARGE LAMP Filed March 14, -1941 lrwentovs Kurk Josb, WOLfF am Thoure Their A'ttor'neg.

lPatented Nov. 25,.v l

UNITED STATES PATENT OFFICE GASEOUS DISCHARGE LAMP Kurt Jost, Berlin-Pantom'and Wolfgang Thou;

ret, Berlin-Wilmersdorf,

General Electric Company, a corporation of New York Application March 14, 1941, Serial No. 383,404 In Germany March 7, 194e several discharge arcs playing' between the elecf other terminal of a D. C. source. The series re- Y trodes produce a uniform illuminatingsurface.

In one oi the disclosed forms the discharge bulb may contain two opposed parallel rows of two or more electrodes each of which rows produce 'cross arcs between diagonally disposed electrodes in addition to theparallel arcs between directly opposed electrodes. This is accomplished .by

-using either several current sources, for example several secondary windings oi a transformer. or by using phase-displacing impedances. YIn `the latter case the arcs are displaced in phase and, although they give the impression of a uniform illuminating surface to the naked eye owing to their rapid succession, they might be objections able in various fields of application, for example in motion picture projection, owing to the stroboscopic effect. Now we have found that it is possible to obtain a high-pressure discharge lamp of the aforesaid type which is free of these objections byA employing a novel arrangement of the electrode and circuit elements.

Accordingly it is an object of our invention hto provide a lamp of the aforesaid type which shall be free of the aforesaid objections and which may be operated from a single power source of either direct or alternating current. Further objects and advantages of our invention will lippear from the following detailed description and accompanying drawing.

Generally speaking, the objects bf the inven b tion are accomplished by amusing the opposed parallel rows of electrodes in such a manner that the distance between the two rows of electrodes is made at least twice the distance between the electrodes of'a single row and, in addition, by making the series resistance of any one glow electrode twice as large as the series resistance of an adjacent electrode of the same row.

Referring to the drawing, Figures 1 and 2 illustrate alternative forms of .discharge lampe designed V according to the'invention, the arcs being indicated by dashes.

3 Claims. (Cl. 176-124) In the 220 volt D. C. lamp shown in Fig. 1, the spherical quartz bulb l contains two rows of electrodes 2, I fed by thedischarge, each row having four electrodes which are preferably of the activated type. The spacings between the electrodes of one row areA about 6 mm. between the tips where the arc plays while the distance between the two rows of ciectrodesis about 15 mm.,

that is, at least twice as-large.

Each of the electrodes I of the lower row is connected through a vacuum-tight sealed molybdenum foil I and a series resistance 'I to the sistance l of the iirst electrode oi' the upper row and also the series resistance i., of the last eleci ohms, while the magnitudev of the series resistances or the other electrodes is only 2 ohms. When sucha lamp, which Ycontains'as usual a trode of the lower row has a resistance of about y `iundaxnental filling of rare gases and mercury which,y is completely evaporated during the starting process. 1 5 switcheli on, the four parallel arcs I are produced. The dierence in the chosen values of the series resistancesl causes such voltage drops across theseries resistances and consequent potentiall diile'rences between the electrodes that rfor the given electrode spacings the three additional cross arcs S are produced. These interconnect the four parallel arcs 8 as shown. All the seven arcs carry the same discharge currents of about 6 amperes at an operating vapor pressure of about 25/atmospherea. The seven 'high-pressure arcs cause a remarkably uniform 15 x 18 mm. illuminating surface of very high intensity. v

Fig. 2 shows a high-,pressure 110 volt discharge lamp-.with two rows of three electrodes each.

Inthlscasetheserlesreaistancesareofsucli.

magnitude that the series resistances i of the glow electrodes of the upper row are in the ratio of 3:1:3, and the series resistancesl o! the corresponding opposite electrodes of the lower row are 'as 1.5:3:1.5. The magnitude o! the may be. for example, 1, 1 .5 and 3 ohms respectively.- The spacing between the rows of electrodes is 10 mm.; the spacings be@ tween the electrodes of the samerow are about 4 mm. In this lamp the two cross at the middle upper electrode.

In bothexamples shown in the drawing the series resistances are of such magnitude that the voltage drops across the upper 'and 'lower series resistances are thc'same. The same discharge coniigurations may naturally also 'be obtained arcs strike the lower row are reduced and the series resist-r ances of the .electrodes of the upper row are increased in proportion. The potential of the illuminating field is then brought closer to the potential of one of the poles of the current source. When an A. C. source is used instead of a D. C. source, choke coils or capacitors may be used instead ot ohmic resistances, the discharge arcs produced then all being in phase.

may be obtained. All these we aim to include within the scope of the appended claims.

What we claim as new and desire to secure by letters Patent of the United States is:

l. In combination, a gaseous electric discharge device comprising a sealed envelope and opposed series of two or more electrodes each in said envelope and so positioned that electrical discharges between the various electrodes produce a high intensity source of light covering a major portion o! the area bounded by said electrodes, a source of power, a set of impedances in series connection with each oil said electrodes of both series of electrodes, means for electrically connecting the electrodes of one said series through their impedances to one pole of said source, and means for electrically connecting the electrodes of another of said series through their impedances to another pole of said source, the distance between said series being at least twice as great as the distance between individual electrodes of each series, and said impedances being so proportioned that at least one of said impedances in at leastone of said series is approximately twice as great as an adjacent irnpedance in the same series whereby cross arcs are formed between said series oi electrodes.

2. In combination, a gaseous electric discharge device comprising a sealed envelope and opposed a source of power, a set ol' impedances inl series.

connection with each of said electrodes of both series electrodes, means for electrically connecting the electrodes of one said series through their impedances to one pole o! said source and means for electrically connecting the electrodes of another of said series through their empedances to another pole of said source, the distance between said series being at least twice as great as the distance between individual electrodes of each series, and said impedances being so proportioned that the impedance in series'with the nrst electrode oi' one series and the impedance in series with the last electrode ci another series are at least about twice as large as the impedance in series with any other electrode in the same series whereby cross-arcs are formed between said electrodes.

3. In combination, a gaseous electric discharge device comprising a sealed envelope and opposed series of three or more electrodes each in said envelope and so positioned that electrical discharges between the various electrodes produce. a high intensity source ot light covering a major portion of the area bounded by said electrodes, a source of. power, a set oi' impedances in seriesconnection with each of said electrodes of both series of electrodes, means for electrically connecting the electrodes of one, said series through their impedances to one pole of said source, and means for electrically connecting the electrodes of another of said series through their impedances to another pole of said source, the distance between said series being at least twice as great. as the distance between individual electrodes of each series, and the said impedances in one series being in the approximate ratio 3:1:3 and the impedances connected to corresponding electrodes in another series being in the approximate ration 1.5:3:l.5 whereby cross arcs are formed between said electrodes.

KURT JOST. WOLFGANG THOURET.

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