US1659749A - Electric incandescent lamp and method of manufacturing its illuminating body - Google Patents

Description

UFACTURING ITS Feb. 21, 1928.

F. SKAUPY ELECTRIC INCANDESCENT LAMP AND METHOD OF MAN ILLUMINATING BODY Filed Dec. 2,

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Patented Feb. 21.1

UNITED STATES PATENT, OFFICE.

FRANZ SKAUPY, OI BERLIN, G, ASSIGNOB TO GENERAL ELECTRIC A CORPORATION OI NEW YORK.

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Application filed December 2, 1821, Serial No. 519,400, and in Germany December 4, 1920.

This invention relates to an electric i ncandescent lamp in which transparent bodzgs which are as free of turb1 ess or dimness as possible and are colored preferably cor responding to that portion of the spectrum which in its turn corresponds to the rays to be emitted are caused to glow. As in most cases these bodies themselves are not sufiicientl metal ic conductor that serves as carrier for the current and transfers the current-heat to the transparent part of the illummatlng body, the union'being effected in a manner ensuring good transfer of the heat, preferably by applying the metallic conductor to the transparent conductor in the form of a thin small layer either upon the outer surface or, if the transparent conductor is of tubular shape, upon the. inner surface of the same also. As a metallic conductor has a comparatively uneconomical radiation which extends over all portions of the spectrum including some which are undesirable, its radiating surface must be as small as possible in order to make its rays practically insignificant in comparison to those of the transparent colored part of the illuminating body and to make it serve mainly for the currentconduction and the heat transference, so that the chief amount of the radiation issues from the transparent part. The metallic conductor, in. order to be able to transfer the heat as uniformly as possible to all portions of that transparent part should not be too distant from anyportion of the illumihating body. That is attained best by making the metallic conductor form a spiral upon the transparent partilthe arrangement being then preferably suc that the axis of the spiral coincides with the axis of the illuminating body.

In devices of the prior art either opaque metallic or opaque non-metallic illuminating bodies for instance oxidic bodies, have been used, the main radiation of which, with the temperatures mostly employed, lies for the greater part in the invisible portion of the spectrum, whereby the greatest part of the energy spent is consumed in the production of rays of an undesirable wave length. But lamps manufactured according to the present invention. have a pure or nearly pure selective radiation which is the more economic the less theilluminating substance conductive, they are united with a em loyed absorbs and emits waves of an un esirable length and the smaller the radiating surface of the metallic conductor is by which the current heat is transferred. It might, thus, on principle, be possible to produce a nearly absolutel economic lamp in which nearly the totaf ener spent is transformed into radiation of the esired wave length, that is to say (apart from special cases where invisible light, for instance ultra-red light, is to be converted) into visible light.

The trans arent substances existing in nature or capa le of being manufactured in a chemical way, are unsatisfactory because they emit light of an undesirable wave length and contain turbidities, impurities of the electric and the like which radiate dark waves.

Nevertheless, there may substances be found 'which are sufliciently free from this drawback and yield a satisfying output of li ht, especially if v such substances are suita ly colored by admixtures of slight quantities of substances of another color. To prevent the coloring substances from rendering the trans parent substance opaque, they must either alreadyexist in their base substances in the form of a solid solution or an isomorph admixture or in a highly dispersed colloidal state, especially near to and at the surface of the respective base-substances, or must be applied to the outer surface of the same.

My invention contemplates the use of iioilerate temperatures of the illuminating or y. To obviate structural changes of the illuminating body by the high temperature whereby the transparency would be diminished and the illuminating effect changed, as easily occurs with glassy substances or with substances forming small crystals, the transparent part of the illuminating body may be manufactured, according to this invention,

from one crystal or from a few crystals or 7 crystal pieces, similarly as done with the Wolfram crystal thread in the manufacture of incandescent lamps, One chooses crystals that are free from turbidness or dimness, also as free as phenomenon, an colored by admixtures and shaped as desired and required, by melting. To manufacture them, similar methods ma advan- V tag eously be employed as are m e use of cpossible from the Tyndall I transparent; they may be for the manufacture of artificial precious stones, for instance rubies. Or pulverulent substances may be pressed to form little bars which are heated to such a high temerature as to completely sinter-until they come transparent. The heating is pref erably carried through in a vacuum, either by means of an external source of heat, for instance an electric furnace, or by electric heating of the little bar itself which is rendered conductive either by pre-heating it or by a heat-conductin connection with a me tallic conductor. his latter may be the same as that serving in the finished lamp for transferring the current heat. If the bar itself is made conductive, substances a purpose in trides, carbi es, sulphides, flourides, and esmay be added which first increase its conductivity and then evaporate at, high temperature. The heating is in such a case efl'ected preferably by alternating current of a rather high frequency, of the order em-' ,ployed in wireless telegraphy, the purpose being to obviate electrolytic phenomena. The

resulting transparent body should, from obvious reasons, be as free as possible from electrolytic conduction. In' cases where a certain conductivity of thetransparent body cannot be obviated, the metallic conductor is preferably arranged in the form of a few axial strips either upon the surface of its base or within this latter, the axial strips being in either case connected in parallel with each other. v

As transparent substances suitable for the uestion, heat-proof oxides, ni-

pecially' such substances as oxide of thorium, oxlde ofi-scandlum, oxlde of magnesium, and

the like may be em loyed; furthermore the corresponding nitri es, also boron-nitrogen. As coloring substances suitable for the purpose in question ma be employed fire-proof oxides, such as oxi e of cerium, especially, however, substances which in a thick layer show metallic brightness, but-are transparent and colored in a thin layer, as is the case with the nitrides of titanium, zirconium, some low oxides, such as that of titanium, but also with certain metals themselves.

The metallic conductors which are the intermediaries for the transfer of the heat to the transparent substance consists of metals or conductive compounds of high fusing point, such as tungsten, osmium, tantalum g raphite, titanium-nitrogen, and the like. he layers or coatings consisting of them, for instance spirally wound coatings, may be made by ap lying to the transparent substance a colloi al solution of the respective conductor in the form of a small stri and then heating the whole body in' a suitable atmosphere in order to sinter it. Instead of the colloidal solution of the conductor a the respective substance may be ma e use of,

for instance colloidal Wolfram acid, and the coating may be subsequently converted into metal by. heating it m a reducing atmosphere. Coatings of the kind in question may also be applied by cathodic dispersion.

The coatings may also be applied by those ting body; and Figure 3 is also a similar illustration showing a third form of execution.

Referrin bar of oxi e of thorium is provided with a spirally shaped coating or layer of tungsten or osmium, the ends of which are conductively connected with the feed wires 3 and 4 of the bar 1. The spaces between the con- .volutions of the spiral 2 and the bar 1 are covered with a. thin transparent coating or to Fig. 1, a transparent little layer of titanium-nitride. The ends 6 of the illuminating body are appropriately thickened in order to prevent the feed wires from becoming as hot as the effective'parts of the illuminating body, because said ends, otherwise, would radiate away too large an amount of energy For the rest, concerning the connection of the feed wires with the illuminating body, for instance with themetallic.

layer of this latter, all the methods known in connection with the manufacture of Nernst-lamps may be employed. 1

If the transparent base substance of the illuminating body, which carries the metallic conductor, is not or cannot be, sufliciently colored, transparent colored substances of macroscopic dimensions may be embedded into, or made to contact with the outside of it. Several substances of different colors may be embedded into the same base substance, those substances emitting them, according to their colors, a correspondin l differently colored light whereby particul effects may be produced.

Corresponding to the chemical proper- .ties of the illuminating body the same may be made to light in the free air, in evacuated vessels or in vessels filled with gases of the proper kind. The bulbs are filled with gases that are bad conductors of heat, for instance argon gas and. thelike, or with a as for instance nitrogen, which counteracts y its partial pressure the dissociation of the substance of the illuminating body, especially in the case where a nitride forms part of the illuminatin body.

The conductor whic transfers the heat may be a wire, if it is brought into suitable heat conducting relation with the transparent substance by being melted or pressed into, or being made to contact with the outside of it. p,

As the illuminating bodies constructed according to this invention emit in most cases per unit of surface a by far lesser amount of energy than do the known illuminating bodies of incandescent lamps, they may be considerably larger thanthese latter,

. concerning their breadth, as well as their thickness. And as the current is supplied not through'the transparent main portion of the conductor, but through the metallic conductor, the former may have the most varied forms; it may be a disk,-a ball, a figurative representation, writing characters of any kind, and the like, andthe various trans arent parts ma be made to light with. diferent colors. 2. mild, not dazzlin light and is in this respect somewhat similar to electric gas lamps with glow discharge. p

V Fig. 2 shows a lamp, the illuminating body of which is a lens-s aped disk 7 around which the current conductlng layer runs in a spirally-shaped way. The lamp shown in Fig.3 has an illuminating body with parallel axial strips 8. No potential difli'erence can arise between these strips and, conseuently no transverse current can pass t rough the illuminating substance.

I claim:

1. In combination, a body which when heated-radiates selectively'and which is substantially transparent to waves differing from those radiated, and means for heating said body to cause it to so radiate. J

2. In combination, a body which when heated radiates selectively and which is substantially transparent to waves differing from those radiated, the major portion of the selective radiation falling within the visible range of the spectrum and means for heating said body to cause it to so radiate.

3. In combination, a body in macro-crystal form which when heated radiates selectively and which is substantially transgarent to waves differing from those radiate and means for heating said body to cause it to so radiate.

4. In combination, a body in macro-crystal form which when heated radiates selectively substantially'the major portion of the energy imparted to it by heating, and a device for heating said body to cause it to so radiate.

5. In combination, a body which when heated radiates selectively, said body being clear and in macro-crystal form, and means for heating said body to cause it to so radiate.

6. In combination, a body which when heated radiates selectively, said body being in transparent macro-crystal form, the major portion of the selective radiation falling t any rate, the lamp emits within the visible range of the spectrum, and means 'for heating said body to cause it to so radiate. Y

7-. In combination, a body having the form of a. transparent macro-crystal, and having the propert of selectively radiatin li ht when heate means supported by said rst body for heating the latter to cause it to so.

radlate.

8. In combination, a bod in the form of a clear macro-crystal, said y having the property of selectively radiating li ht when heated, means supported by said body for heating the latter to cause it to so radiate.

9. In combinatiomfa'clear body which when heated radiates selectively, and electric means for heating said body to cause it to so radiate.

10. In combination, a .bod which when heated radiates selectively an which is substantially transparent to Waves difiering from those radiated, and means for heatin said body to cause it to so radiate, said body consisting of athorium com ound.

' 11. In combination, a bod w ich when heated radiates selectively an which is substantially transparent to waves differing from those radiated, and means for heatingsaid body to cause it to so radiate, said body consisting of an oxide of a metal.

12. In combination, a body which when heated radiates selectively, and which is substantially transparent to waves differing from those radiated, and means for heating said-body to cause it to so radiate, said body consisting of a com ound of one of the metals which has a hig fusing point. 13. In combination, a transparent body, a second body in intimate thermal contact with said first body, which second body when heated radiates selectively and is substantially transparent to waves differing from those radiated, and means for heating said first body to cause it to heat said second body to cause the second body to so radiate.

14. In combination, a transparent body, a second body supported by said first body, which second body when heated radiates selectively and which is substantially trans parent to Waves difi'erin from those radiated, and means for heating said first body to cause it to heat said second body to cause the second body to so radiate.

15. In combination, first a transparent body, second a body in intimate thermal contact with said first body, which second body when heated radiates selectively and is substantially transparent to waves difiering from those radiated, and means for heating said first body to cause it to heat said second body to cause the second body to so radiate, said second body consisting of a metallic oxide.

16. In combination, first a transparent body, second a body in intimate thermal contact with said first body, which second body body, second a body in intimate thermal contact with said first body, which second body when heated radiates selectively and is substantially transparent to waves differing from those radiated, and means for heating said first body to cause it to heat said second body to cause the second body to so radiate, said second body consisting of a substance which in a thick layer has a brilliant metallic color and which in a thin layer is trans: parent and colored.

18. In combination, first a transparent body, second a body supported by said first body, which second body when heated radiates selectively and which is substantially transparent to waves differing from those radiated, and means for heating said first body to cause it to heat said second body,

to cause the second body to so radiate, said second body consisting of a substance which in a thick layer has a brilliant metallic color' and which in a thin layer is transparent and colored.

19. In combination, first a transparent 17. In combination, first a transparent body, second a body in intimate thermal contact with said first body and which when heated radiates selectively the major portion of the energy imparted to it by heating, and means for heating said first body to cause it to heat said second body to cause the second body to so radiate.

'21. In combination, first a transparen .body, second a body supported by said, first is volatile at high temperatures to render a the material conductive and in passing a high frequency alternating current through said material until it is sintered and heating until the conducting substance volatilizes.

23. In combination, a body which when heated radiates selectively, and which is substantially transparent. to waves differing from those radiated, and means for heating said body to cause it to so radiate, said body consisting of a compound of one of the refractory metals which has a high fusing point.

24. In combination, first a transparent body, second a body supported by said first body, which second body when heated radiates selectively and .which is substantially transparent to waves diflerin from those .radiated, and means for heating said first body to cause it to heat said second body to cause the second body to so radiate, said second body consisting of cerium oxide.

In testimony whereof I aifix my signature.

FRANZ SKAUPY.

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