US2235711A - Electric discharge lamp - Google Patents

Electric discharge lamp Download PDF

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Publication number
US2235711A
US2235711A US621436A US62143632A US2235711A US 2235711 A US2235711 A US 2235711A US 621436 A US621436 A US 621436A US 62143632 A US62143632 A US 62143632A US 2235711 A US2235711 A US 2235711A
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discharge
lamp
electrodes
electrode
lamps
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US621436A
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English (en)
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Danzer Catherine
Randa General Conrad
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General Electric Co
CBS Corp
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General Electric Co
Westinghouse Electric and Manufacturing Co
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J61/00—Gas-discharge or vapour-discharge lamps
    • H01J61/64—Cathode glow lamps

Definitions

  • the present invention is based upon the recognition of the fact that this light phenomenon of the cathodic discharge parts" is far more suitable for development as an efiective source of light than is the positive column, especially if the lamp is to have the usual dimensions and candle power of incandescent lamps.
  • the invention proceeds systematically from the endeavour to weaken as far as possible, or completely to suppress, the positive column or the light phenomenon corresponding thereto, and, on the other hand, to bring to the greatest possible development the light phenomenon adjoining the hot cathode and therewith connected.
  • cathodic discharge parts and cathodto light phenomenon In a physical sense most gas discharges are not uniform phenomena. but arise from several parts sharply distinguished from one another as regards their appearance and behavior. Adjoining the cathode there is always a sphere of discharge, which (in many cases consisting of several zones) is closely connected with the phenomena occurring on the cathode and which appears to be associated, so to speak, with the cathode; for this reason it may be called the cathodic discharge sphere or cathodic discharge part. The close relatlon of this part of the discharge to the cathode may be seen, for example, from the fact that it slavishly reacts to changes of. the position of the cathode, Whereas other discharge parts, such as the positive column, remain substantially unafiected by such changes of cathode position.
  • Another criterion is the manner of development of the light phenomenon located in the cathodic discharge parts and, therefore, designated cathodic light phenomenon.
  • the light phenomenon is compressed, namely, towards the electron-emitting surtace oi the cathode, and gains volume from the surface of the cathode outwards, if the gas pressure he reduced.
  • the temperature of the hot cathode should not be chosen too high, presumably on account of its influence upon the temperature of the neighboring cathodic discharge sphere. It has been proved that the desired cathodic light phenomenon, for instance when tungsten is used for the electron emitter of the hot cathode, does not come into being. For this reason the invention is confined to lamps the hot cathodes of which emit abundant electrons even at a relatively low temperature. For this purpose substances should preferably be used which emit a sufllcient number of electrons even at 1000 C. or less. Materials capable of such emission and answering these requirements are, for instance, the oxide compounds of the alkaline earth metals or these latter themselves. The reduction of the emission temperature also promotes the ciliciency of the lamp.
  • the shape of the lamp bulb especially where it limits the discharge between the electrodes, has in most cases considerable influence upon the coming into being, or the suppression, of the positive column. Narrow waisting of the discharge in the space between the electrodes favors the creation and development of the positive column and at the same time hinders'the extending of the cathodic light phenomenon, which is prevented, so to speak, by the positive column from penetrating into the waisted portion of the lamp. Effort is, therefore, made to limit as little as possible the cross-sectional dimensions of the discharge space between the electrodes, 1. e. the dimensions at right angles to the discharge path, so that, for example, in the case of 8.
  • cylindrical bulb with electrodes arranged at the ends thereof, short and wide cylinders are pref erable to long and narrow tubes.
  • waisting of the vessel in the space between the electrodes should as far as possible be avoided, even if such waisting were to be eflected at individual points only.
  • a type of lamp in accordance with the present invention it is possible to proceed from a given shape of bulb and, by reducing the distance between the electrodes and diminishing the gas pressure, to ascertain by experiment the dimensions at which the cathodic discharge parts are the principal or even sole source of the light emitted by the lamp.
  • the light phenomenon proceeding from the emitting hot cathode surface appearing to expand outwards.
  • the light phenomenon which is at first confined to a small space bordering on the hot cathode, will, as the gas pressure diminishes, fill up a constantly growing space in the lamp, and extend as far as the electrode acting as anode or even beyond the same, so that this latter lies wholly or partily within the luminous gas, that is to say within the cathodic discharge parts; in many cases the expansion of the cathodic light phenomenon may proceed so far as to reach the wall of the lamp and thus to fill the whole of the bulb.
  • Enhancing the electron emission of the hot cathode and directly or indirectly increasing the density of the discharge current have the same efiect as reducing the gas pressure. In general these steps enhance the intensity of the light emitted, and here again the danger of destroying the emissive layer and of overheating the wall of the vessel determines the limit which should not be surpassed. It will be clear that the working values for the emission temperature, current density, gas pressure, and other factors cannot be chosen independently, but must be properly adjusted relatively to each other.
  • the special construction and or rangement of the electrode acting as anode are immaterial for the creation and developement of the cathodic light phenomenon, provided, of course, that-for the given gas pressure-the maximum spacing of the electrodes required for the suppression of the positive column be not surpassed, and the anode be not so arranged that injurious wall influences can play an important part.
  • the cathodic light phenomenon is distinguished from that of the positive column, which always remains confined to the space between the electrodes..
  • the cathodic light phenomenon If the anode should be enclosed within M the cathodic light phenomenon, it must not beso constructed that a considerable gas zone adjoining it is totally screened on by it from the electric field. Such would be the case, for instance, if the anode enveloped the hot cathode like a cage or with the screening efiect oi? an electrostatic cage; in such a case the cathodic light phenomenon could not extend into the space outside of the cage.
  • the surface of the anode is, therefore, generally chosen no larger and often even much smaller than that or the hot cathode; for instance by the use of a simple wire as anode. The fact that this is possible without impairing the production of light and the working capacity of the lamp constitutes a further. advantage of the invention.
  • Alternating current lamps in accordance with the invention in which the two electrodes are constructed as hot cathodes and function inconsecutivehalf cycles as hot cathode and anode alternately, are especially favorable, in that the light radiation is unhampered, since at a sunlciently high frequency of alternating current the eye sees simultaneously and uninterruptedly the light phenomenon occurring in both half cycles, so that to each electrode there appears to be connected at cathodic light phenomenon, which in dill till
  • Ehe invention not only improves electric rare gas lamps in regard to their luminosity by making an extremely efiectively radiating but up to the present not appreciated and in any case not exploited portion of the luminescent discharge into the source proper of light, but also constitutes progress in regard to the size and current dependency of the voltage employed, and in regard to uniform heating of the hot cathodes. Efforts have long been made to reduce as far as possible the operating and discharge voltage of rare gas lamps, and more particularly in this direction was the hot cathode introduced in place of the cold cathode. But even with hot cathodes success was not achieved in obtaining discharge voltages (voltage drops) substantially be- I low 50 volts.
  • the numerical value for the minimum voltage depends upon the nature of the gas filling. In lamps the filling of which contains neon it is about 16 volts, but in any case less than 25 volts. In such lamps the gas pressure and the electrode spacing will therefore be diminished until the voltage drop values of the above-mentioned order are obtained.
  • the discharge voltage is depend ent on the discharge current, however, also renders possible an improvement in the heating of the hot electrodes. It is clear that a constant heating of the hot cathode or hot electrodes is of great importance in the operation and utility of thelamp on account of the electron emission depending thereupon. While the heating current in the known rare gas lamps with indirectly heated hot cathode either depends upon an operation factor subjectto. unavoidable fluctuations, such as ordinary line voltages, or is supplied from a special source. of current, it may, according to another execution of the invention, be automatically kept at practically constant value, after the starting of the lamp has taken place, irrespective of the intensity of the discharge current.
  • the values for the gas pressure and for the electrode spacing required for the carrying out Ill! of the invention will be different for different constructions of lamps, and will depend upon the kind of gas filling, the shape of the bulb, the size and nature of the electrodes, and other factors, so that it is hardly possible to lay down a generally, valid rule in regard to numerical and theoretic values.
  • a further matter for consideration is the predominant point of view from which the designing of the lamp is governed, that is to say whether the purpose is chiefly to suppress the positive column or to arrive at the minimum discharge voltage or the current dependence thereof.
  • the object aimed at is most rapidly reached with the aid of a few comparative experiments. These experiments cause no difficulty when once the present invention has clearly shown the ways by which the desired features can be realized.
  • the electrode spacing will not be made too great, for instance less than 50 mm., but the latter can also be reduced as low as 2 mm.; a short lectrode spacing is advisable particularly with alternating current lamps with two hot electrodes. However, with these small lamps any electrode spacing often sufilces, so thatonly the range of the necessary gas pressure remains to be determined.
  • any rare gas or rare gas mixture is suitable as a gas filling for the lamp, and metal vapor, particularly mercury vapor, can also be added to the filling.
  • the cathodic light phenomenon becomes especially intensive and suitable for practical use as a source of light, if the gas filling contains neon alone or neon mixed with other gases or vapors. It has been observed that the light of such lamps (and especially of lamps containing neon and mercury vapor) greatly surpasses in brilliance and in favorable physiological effect that of similarly constructed lamps containing no neon, and that particularly the neon-containing lamps constructed in accordance with the invention prove the qualification of the cathodic light phenomenon to be used as a practical source of light.
  • the cathodic light phenomenon consists in most cases, especially with gas fillings containing several gases or vapors, but often also with pure gases, of two or more zones of different light in tensity and sometimes of different colors, where by the zone adjoining the hot cathode (hot electrode) always possesses the greatest light in-' tensity, and constitutes the most efficient portion of the phenomenon optically.
  • This inner zone gives the impression that it corresponds to the immediate sphere of action of the electrons emitted by the -hot cathode, 'and' this conception is supported not only by its dependence in extent some secondary effects of the electron emission from the hot cathode. It must, however, be stressed that these views of the individual zones are only hypothetic conceptions, which perhaps possess euristic value; they might, however, equally well be replaced by explanations of an entirely diderent hind.
  • the lamps according to the invention can be operated with either direct or alternating current. In the former case it sumces to develop the cathode as an. indirectly heated hot cathode; nevertheless, lamps with two ormore hot elec trodes are also suitable for operation with direct current. ps operated with alternating current can most advantageously be provided, for the reasons given above, withtwo similar hot electrodes, but, owing to the rectifying'eflect,
  • lamps with a single hot electrode can be made Fig. 2 an alternating current lamp, both with globe-shaped vessels; these figures also show the wiring serving to keep the separate heating cur rent constant.
  • Fig. 3 a lamp is illustrated with cylinder-shaped vessel, while Fig. 4 shows a tu bular in order to explain the influence of the narrowing of the vessel between the electrodes; the lamps in Figs. 3 and 4 possess two hot tube is connected with the respective terminal of the director alternating-current source, and this is most simply done by means of a conductive connection between the little tube and the leading-in wire for the heating wire 2 the heating circuit and the discharge circuit may, however, also be completely separate.
  • the heating circuit is in parallel to the gas discharge path, and, since "the lamps of these figures possess the characteristics indicated in Fig. 5, which shows the electrical starting characteristics whereby the discharge voltage beginning from the starting point Z runs independently of the current (parallel with the axis of abscissae), the current passing through the heating wire 2 will always retain the same value for different values of the discharge current. In consequence of this fact, even at relatively high discharge currents the lamp will only consume the extra heat necessary for starting.
  • the interior wiring. of the heating circuit (which can embrace one or both electrodes) can be of any kind, and any desired type of resistance may also be included in the heating circuit.
  • the hot cathode I is completely coated with an electron-emitting, layer, it is enclosed by the cathodic light phenomenon the innermost zone of which is indicated by the dotted outline 4, so that the electrode in no way interferes with the light radiation.
  • the anode 3 in Fig. 1 takes the form of a plain wire of small superficial area, it, too, will scarcely obstruct the path of the light rays.
  • the cathodic light phenomenon will extend in most cases up to the wall 5, unless the latter be of unusually large dimensions; in short cylindrical lamps also, of the type shown in Fig. 3, the cathodic light phenomenon may in some cases occupy the entire lamp bulb.
  • the discharge voltage with neon fllling is, in lamps of the type shown in Fig. 3 (except where'the electrodes are very close together) greater than in the case or those shown in Fig. 1 and Fig. 2, and amoimts for example (at the weakest appearance of the positive column), to about 25 volts. In lamps of the type shown in Fi 4, the discharge voltage is still higher and, especially if a strong positive column appears, exceeds volts.
  • Fig. 5 shows, for a lamp as shownin Fig. 2, the dependence of the main voltage (operating voltage) E 01. the lamp upon current I passing into the lamp;
  • the broken line portion 01 the characteristics' shows the voltage rise up to starting (Z), the operating current of the lamp being then identical with the heating current of the heating circuit.
  • Lamps according to the invention are very suitable for low-voltage lamp series connection, since in the event of one of the lamps in the series burning out, the defective lamp is recognizable by the appearance of an are light between its electrodes. Further,,burnin out in consequence of voltage fluctuations is rendered very unlikely by connecting the lamps as shown in Fig. 1 or 2.
  • An electric discharge lamp containing a monatomic gas at a pressure of less than ten millimeters of mercury and having at least one indirectly heated electrode of the type which emits electrons at temperatures preferably below 1000 (3., the electrodes being spaced so near one another, snd the pressure of the gas being so chosen with respect to said spacing, that the discharge is restricted to a cathodic glow and the positive column is substantially eliminated entirely.
  • An electric discharge lamp containing a monatomicgas at a. pressure of approximately one to five millimeters of mercury and having at least one indirectlyiheated electrodeof'the type which emits electrons at temperatures preferably below i000 6., the electrodes being spaced so near one'another, the dimensions or the dis-.
  • an electric discharge lamp as defined in claim 1, wherein the monatomic gas is neon and which contains also mercury vapor.
  • An electric discharge lamp as defined 'inclaim 1 having 9. containing vessel which is substantially spherical.
  • An electric discharge lamp as defined in claim 1 wherein the product of,,.the gas pressure measured in millimeters of mercury and the elec- M t xade spacing measured in millimeters is less than lamp as defined in 'claim 1, having a containing vessel which is sub- 18.
  • An electric illuminating lamp comprising a bulb, two closely spacedgelectrodestherein at leastone of which is capable of emitting electrons freely when heated, a resistance member capableof heating said electrode to its electron emitting temperature, one end ofwhichresistance member is connected to the electron emitting electrode and the other end thereof to the other electrode to-permit the application of a potential between said electrodes, and a rare gas filling for said lamp, the pressure of said gas filling being such that at the electron emitting ing potential of the lamp a luminous gaseous discharge arises in the form of expanded cathodic light.
  • An electric filling two spaced electrodes at least one of which is capable of emitting electrons freely when heated, and a resistance member for continuously and indirectly heating said electrode to its electron emitting temperature, one end of said resistance member being permanently connected ous discharge arises in the form of expanded cathodic light.
  • An electric illuminating lamp for alternating current comprising a bulb, two co-operating electrodes therein each of which is capable of emitting electrons freely at relatively low temilluminatlng lamp for alternatlng current, comprising a bulb, a rare gas' temperature of said electrode and at the operatperature, a resistance heater for continuously and indirectly heating said electrode, one end, of each resistance heater being permanently connected to its electrode, alow resistance bridge l permanently connecting the other ends of said resistance heaters, lamp terminals permitting electric current to be supplied to said heating member and a potential to be applied between the electrodes, and a rare gas filling for said lamp, the pressure of said filling and the electrode separation being such that at the electron emitting temperature of said electrodes and with an interelectrode potential approximately of the order of the ionizing potential of the rare gaa no appreciable positive column can arise.
  • An electric discharge lamp which provides useful illumination by expanded cathodic light which comprises a monatomic gas filling at a pressure of less than 10 millimeters of mercury and having at leastone indirectly heated electronemissive electrode, the density of the discharge at any given pressure of said gas filling being such that a luminous gaseous discharge arises in the form of expanded cathodic light.
  • An electric luminous gaseous discharge lamp comprising, an envelope having an ionizable medium therein, co-operating metal electrodes at least one of which is capable of emitting electrons freely when heated to a relatively low tem perature, a resistance heater for continuously and indirectly heating said electrode during the operation of the lamp, a lead-in wire for each electrode, and permanent connections within the envelope between said heater and the electron emitting electrode such that the gaseous dis-- charge path is electrically in parallel with the resistance heater.
  • An electric luminous gaseous discharge 26 An electric luminous gaseous discharge lamp comprising, an envelope having an ionizable medium therein, a metal anode, another metal electrode which is capable of emitting electrons freely when heated to a relatively low temperature, a resistance heater for continuously and indirectly heating said electrode during the operation of' the lamp, and permanent connections within the envelope between one end of said heater and the emissive electrode on the one hand and between the other end of said heater and the anode on the other hand.
  • An electric luminous gaseous discharge lamp comprising, an envelope having an ionizable medium therein, two similar co-operatlng metal electrodes each of which is capable of emitting electrons freely when heated to a relatively low temperature, a resistance heater for continuously and indirectly heating each electrode during the operation of the lamp, 2. permanent connection within the envelope between each electrode and one end of its heater and a low resistance bridge connecting the other ends of said'heaters.
  • a gaseous discharge device comprising an enclosing envelope having an ionizable medium therein, a plurality of spaced apart electrodes of the indirectly heated type within said envelope and separate means for heating each of the said electrodes, said means being connected in series and connected to the electrodes.
  • a self-regulating glow discharge device comprising a bulb having a gaseous filling, an
  • I electrical circuit including an electrode and a thermionically active cathode, a heater element for said cathode, a source of electrical energy .to supply a given amount of current for said circuit to heat said element to render said cathode electron emissive, said cathode being so arranged with respect to said circuit as to bypass a portion of said current supply through said cathode to said electrode to cause a glow discharge therebetween, whereby the amount of current passing through said heater element is reduced and the operation of the device controlled.
  • a device comprising a sealed envelope having therein an ionizable medium, a plurality of 32.
  • a glow discharge device an hermetically sealed envelope, an ionizable medium therein, a plurality of spaced apart heater elements within said envelope and connected in series, a plurality of electrodes one for each heater element and heated thereby, each of said electrodes being electrically connected to its heater element whereby when alternating current is passed through said heater elements said heaterelements will become heated and in turn heat said electrodes to electron emitting temperatures thus causing a portion of the current to flow between said electrodes and ionize the said medium, an increase in said electrode current causing a decrease in said heater current whereby the electrode current will be caused to diminish and vice versa.
  • a discharge device comprising a bulb having a gaseous filling, a press, conductive support wires extending from said press, heater elements disposed in spaced relation and each having an and electrical connections between said supports and said members.
  • a gaseous discharge device comprising an enclosing envelope having an ionizable medium therein, a plurality of spaced apart electrodes of the indirectly heated type within said envelope and including means for continuously supplying heat to the electrodes during operation of the device, said means being connected in series and connected to the electrodes.
  • a gaseous discharge device comprising an enclosing envelope having an ionizable medium therein, a plurality of spacedapart electrodes within said envelope one of which is' a cathode of the indirectly heated type including means for continuously supplying heat to said cathode during the operation of the device, said means being connected in shunt with the path between one of said electrodes and said cathode.
  • an envelope containing an ionlzable gas, two spaced apart resistance heater elements within said envelope, 9.
  • pair of thermionically active electrodes within said envelope each of which comprises a tubular member surrounding one of said heater elements and adapted to be continuously heated by the latter during the operation of the lamp, a lead-in wire for each electrode, one oi' the ends of each of said heater elements being connected to their respective electrodes at one of the ends or said electrodes, and means within the envelope for 5 connecting the other ends of the heater elements.

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US621436A 1931-07-09 1932-07-08 Electric discharge lamp Expired - Lifetime US2235711A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4521718A (en) * 1983-02-01 1985-06-04 Gte Laboratories Incorporated Beam mode lamp with voltage modifying electrode

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4521718A (en) * 1983-02-01 1985-06-04 Gte Laboratories Incorporated Beam mode lamp with voltage modifying electrode

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FR739783A (fr) 1933-01-17

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