US682695A - Method of controlling gas or vapor electric lamps. - Google Patents

Description

No. 682,695. Patented Sept. I7, 190i.

P. C. HEWITT. METHOD OF CONTROLLING GAS 0R VAPOR ELECTRIC LAMPS.

(Application filed Tan. 25, 1901.)

(No Model.)

- by (EM-1 AM 411% "m: uonms mans co. Pummm'yn. wiuumurou. n. c.

UNITED STATES PATENT OFFICE.

PETER COOPER HEWITT, OF NEW YORK, N. Y., ASSIGNOR TO PETER COOPER HEWITT, TRUSTEE, OF SAME PLACE.

METHOD OF CONTROLLING GAS 0R VAPOR ELECTRIC LAMPS.

OPECIFICATION forming part of Letters Patent N 0. 682,695, dated September 17, 1901.

Application filed January26, 190l- Serial No. 44,647. (No model.)

To all whom it 71mg concern:

Be it known that I, PETER COOPER HEWITT, a citizen of the United States, and a resident of New York, in the county of New York and State of New York, have invented certain new and usefulImprovementsin Methods of Controlling Gas or Vapor Electric Lamps, of which the following is a specification.

My invention relates to a method of producing light by means of electricity traversing a gas or vapor, the special object of the invention being to control the electrical conductivity or resistance of the gas or vapor by means which will be described in the present specification.

I have found that under proper conditions a gas or vapor inclosed within a suitable vessel or container can be made to control the flow of current under the influence of a given difference of electrical potential through the medium of its resistance. I have also found that the electrical resistance of a conducting :gas or vapor bears a definite relation to the density of the gas or vapor. I have further found that it is possible so to control the density of an inclosed gas or vapor acted upon by an electric current as to maintain that density at a predetermined degree, rendering its conductivity sufficiently stable and suitable for service as a light-giving medium, its

efficiency in that respect being exceedingly .great.

h/Iyprescntinvention aims to provide means I for such control of the density of (the gas or vapor which is acted upon by the current' fiowin g as to render its naturally-variable resistance controllable and stable, and thereby produce a highly efficient and commercially useful electric-lighting device.

I have'foundthat the conductivity of a conducting gas or vapor increases as its density decreases up to a certain limit, beyond which decrease of density the conductivity diminishes with further attenuation of the gas or vapor. Starting from the condition of maximum conductivity, in other words, the resistance increases as the result of either an increase or a decrease of the vapor density. The first step toward controlling the density of the gas or vapor is taken when it' is inclosed in a container of definite volume.

When the gas or vapor has been so inclosed, the density of the conducting-path may then be varied by providing outside this path one vor more chambers into which a portion of the gas or vapor can be made to pass or by the condensation or volatilization of suitable material held within the container. The total density is a function of the pressure (as determined by the limits given to 'the container through its length and radius) divided by the temperature. The density in any selected portion of the vapor inside the container depends upon the temperature of that portion as modified by the pressure affecting that portion. The effect of temperature in decreasing the density in a portion of the container by attenuating the vapor may be in part corrected by an increase in pressure.

In an operating lamp the active agent which can be relied upon for producing the eifects of light and heat is the current. In constructing an electric vapor-lamp designed for service as an efficient light-giving medium the object should be to provide means for so controlling the efiects of the current as to make the lamp self-regulating, so that the heat developed by the current shall vary the density of the vapor and incidentally the pressure, the Whole being accomplished in dius of the container, but also throughproperly selecting the thickness of the walls and in some instances providing one or more special cooling-chambers for assisting in the radiating of heat, Inasmuch as the radiation of heat takes place at the circumference the temperature of a vapor through which an electric current is flowing must necessarily vary throughout from circumference to center, being highest at the center and lowest at the circumfergnce. Accordingly a vapor car- To a rying current will have a varying density, decreasing along the radius from the circumference to the center. If now the density of the vapor in the container, where no current is passing, is at or below the density of maximum conductivity, the zone which nearest approaches the state of maximum conductivity when current is permitted to pass will be at the circumference, the vapor resistance increasing along the radius from the circumference to the center inversely as the density due to the attenuation caused by heat from the current. When the density of the vapor in the container is greater than the density of maximum conductivity, the vapor resistance will decrease along the radius of the conducting-column from the circumference to a point Where the vapor is attenuated to the density of maximum conductivity, and from that point to the center the density will be below the state of maximum conductivity, and consequently the vapor will be of greater resistance toward the center.

If we adopt such a density of the contained gas or vapor that the zone of maximum conductivity or the zone nearest approaching that state is at the circumference of the vapor, we run the danger of exposing the substance of the container to injury from the efiects of the current, and in practice I have found that it is not advisable to expose the container to this danger; but I have also found that with a vapor whose total normal density when no current is passing is at or below the condition of maximum conductivity I can select a radius sufficiently large to cause the accumulated vapor at the circumference due to the heat developed when the current begins to fiow to have a resistance greater than that of maximum conductivity, whereby the condition mentioned in the preceding paragraph is attained, or I can select a radius large enough so that the heat generated by the current will not endanger the container. Thus it will be seen that the best available working condition for a lamp of this class is generally one in which the density is somewhat above the state of maximum conductivity. In this condition the zone of greatest conductivity is an annulus located along the radius between the center of the contained tube or chamber and the inner wall thereof. Bearing in mind that the conductivity of the gas or vapor is greatest at a given density J or attenuation, the fact noted indicates that the stratum of gas or vapor between the inner surface of the wall and the so-called conducting zone is of greater density than that of maximum conductivity. The successful operation of a gas or vapor lamp appears to depend upon the proper control of the density of this outer stratum, thus determining the pressure of the said stratum upon the conducting zone and controlling the total conductivity of the lamp. The gas or vapor density in various parts of the container is governed by the temperature of the conducting rate of heat radiation or heat emission therefrom per degree of difference of temperature. As in other electric lamps, the real controlling agent in a gas or vapor lamp constructed to be used at a constant voltage is primarily the resistance; but inasmuch as the resistance of a gas or Vapor depends upon its density, and as the density depends on what may be called the resultant temperature due to the differential effects of the heat developed by the current and the heat radiated or emitted by the lamp, the controlling agent in a lamp of this class is practically the ratio of temperature of the gas or vapor as influenced by the pressure to the heat-dissipating capacity. If this temperature can be maintained definite at predetermined pressure, the ratio of density will be definite, and hence the conductivity or the resistance of the conducting medium will be definite with respect to a definite current. In lamps wherein a vapor is produced by the Volatilization of a suitable substance contained within the tube or chamber the same law holds good, bearing in mind that the density may in crease with the temperature, although in such cases the relation of the volatilizing or boil= ing point of the substance employed to the temperature at which it is intended to 0p crate must be taken into consideration. In such lamps a properly-selected vapor temper ature maintained by the regulation of the heat emission will accord approximately reliable self-regulation, the supply of fresh vapor to compensate for the condensation resulting from any cooling process being automatically responsive to the demands of operation. It follows that a lamp of this character in order to be stable should be so constructed that when the density of the gas or vapor has reached the point thatis best suited for practical operation the rate of emission of heat from the lamp should be the same as the rate of development of heat caused by the passage of the current. In other words, the gas or vapor employed as the conducting medium should be confined in such a manner and with such surroundings that the thermal conditions inside the containing tube or chamber shall remain unchanged or shall correct themselves under varying conditions of imparted heat due to a varying flow of current at any given time. Should the heatradiating capacity of the lamp be either too great or too small with respect to the current, the resultant temperature would cease to be a corrective factor and the vapor density and lamp resistance would be unstable and the lamp would cease to be self-corrective in its action.

In accordance with what has been suggested above, self-regulation in lamps of this class may be attained by subjecting the gas or vaporpath to such surrounding conditions as to secure the radiation or emission of heat at a predetermined rate, or means may be provided in addition to the regula tion of the heat emission for supplying additional vapor, as from vaporizable material, to the conducting medium as the density of the vapor-path tends to become too attenuated and so have a tendency toward increasing the density due to increase of temperature by this means instead of decreasing density.

In the accompanyingdrawings I have illus- I trated several forms and arrangements of gas and vapor lamps adapted to serve for carrying out my invention.

In the drawings, Figure 1 is a section of a lamp adapted to contain a suitable gas the densityof which will decrease with an increase of temperature. Fig. 2 is a similar view of a lamp in which the gas will maintain a constant total density. Fig. 3 represents in section a vapor-lamp containing a volatilizable substance, and so arranged that the density will increase with an increase of temperature. Fig. 4 similarly represents a vapor-lamp wherein the density of the vapor varies in a prescribed manner with the temperature. Fig. 5 represents a vapor lamp with variable vapor density, the same being surrounded by a transparent jacket provided with means for adjusting the amount of heat abstracted at a given time; and Fig. 6 is a similar view of a lamp with constant density surrounded by a transparent jacket with a variable draft to enable varying the temperature the lamp my attain.

In Fig. l the main portion of the container is represented by a tube 1, within which are held two electrodes 2 and 5, of pure iron, the former of which may represent the anode and the latter the cathode. At each end of the tube 1 in this figure I have represented a bulb or enlargement 4 extending beyond the electrodes in such a manner that the gas contained in these bulbs will be mainly outside the conducting-path between the electrodes. The contained gas may be a mercury vapor or nitrogen or other suitable gas. Conductors 7 and 8, of platinum, leading to the electrodes 2 and 5, respectively, are sealed through the glass and covered for a considerable distance inside the container with glass or other good heat-resisting non-conducting material. Generally the covering of such material will extend as far as the electrodes, as illustrated at 10 10. In. the operation of this lamp a portion of the gas or vapor is forced into the bulbs or enlargements 4 4, thus bringing about a condition of variable density within the lamp due to the attenuation caused by the heat of the current.

In Fig. 2 I illustrate a lamp of constanttotal density at all working temperatures. In this lamp the bulbs or enlargements are dispensed with and practically all of the gas or 'vapor is in the conducting-path. The gas or vapor may be a mercury vapor or nitrogen or other suitable gas.

The lamp illustrated in Fig. 3 has as its cathode some volatilizable material, as shown at 5. This material may be a puddle of mercury. In this form of lamp the density of the vapor will increase with the temperature, although the cooling-chamber 4 may serve to condense a portion of the vapor.

Fig. 4 illustrates a modification of the lamp shown in Fig. 3, whereby the density may be made to vary in a prescribed manner with the temperature through giving to the enlargements 4 4 a definite containing and heat-radiating capacity, the enlarged portions lying outside the conducting vapor path.

In'Fig. 5 I show a vapor-lamp containinga volatilizable material, the entire lamp being surrounded bya transparent jacket 18, closed at the bottom and having openings 19 19,-

vwith which similar openings 25 in an adj ustable ring 21 are adapted to mesh when moved to the proper position. The jacket 18 is suspended from a cap 22, through, which the 1eading-in wire 7 passes on its way tothe elec-' trode 2. The cap 22 may be secured to the wire 7 by any suitable means, as by the sealing of the wire into the cap. The connection between the cap and the jacket may be made by means of screws 23 '23, passing through the cap and engaging with a head or beads 24 on the jacket. Where the screws pass through the material of the cap, pieces of metal 25 25 may be secured to the cap in order to hold the screws, or a band or ring of metal may be secured to the cap for the same purpose. 'The upper end of the jacket 18 is open, and within limits any desired draft may be maintained between the lamp proper and the jacket through the regulation of the openings 19 by means of the ring 21. Fig. 6 shows a similar draft-varying device in connection with a lamp similar to the one illustrated in Fig. 2. In this arrangement, however, the draft is regulated at the lower end by the adjustment'in a vertical direction of a cap or end piece 26 through the medium of screw-bolts 27 27, passing through suitable flanges 28 28 on the lower end of the jacket 18 and on the cap or endpiece 26.

The principles laid down in the present specification are embodied'in practical form in a lamp in which the container is of glass, having a bore three-quarters of an inch in diameter, the length between the electrodes being fifty-four inches and the chamber lying outside of the path of the current having a radiating-surface equal to a spherical area three inches in diameter. The positive elec trode will be'constructed of pure iron held in place by a supporting-pillar of glass, through which the platinum leading-in wire passes.- The negative electrode may be a puddle of mercury, as shown, and a platinum leading-in wire extending through the walls of the vessel will connect the mercury with the external cir cuit. Such a lamp will run on a current of approximately one hundred and twenty volts and pass approximately four amperes when the surrounding temperature is that of an ordinary roomsay seventy-five degrees.

The above is given merely as an illustrative lamp. By varying the proportions and dimensions the current consumed by the lamp may be varied from the above within wide limits, and the lamp may be made to adapt itself to the conditions of any circuit, and the lamp may be constructed to run on constant-voltage circuits of wide range of voltage.

The lamp may be started by any of the devices such as are described, for example, in

my pending application, Serial No. 11,605, filed April 5, 1900.

The foregoing specification relates, primarily,to means for controlling the conductivity or resistance of a gas or vapor lamp by the means described, the object being to maintain a uniform resistance or conducting power under generally uniform conditions of outside temperature, as when a lamp of this sort is intended to give light in a confined space. It is possible, however, by varying the external temperature through such means as are illustrated, for example, in Figs. 5 and 6, or by any other simple means, to produce the same conditions of stability under a constant lower temperature; but in that case the lamp resistance will be decreased while the current is increased, as well as the candle-power of the lamp, the electromotive force remaining stationary. Having selected some lower outside temperature, thereby causing a more rapid radiation of the heat, the lamp will regulate itself in the manner hereinbefore described so long as the outside temperature remains at the lower degree. These principles furnish a means for increasing or decreasing the brilliancy of the light emitted by a lamp of this class without impairing its efficiency, as the watts consumed are varied by varying the actual resistance of the lamp itself, as will be readily understood.

In certain other applications filed by mefor instance, Serial Nos. 11,605, 11,606, and 11,607, filed April 5, 1900, and Serial Nos. 44,648 and 44,649, filed January 25, 1901 claims are made to certain features which are disclosed herein.

I claim- 1. The method of maintaining an approximately definite resistance on the part of a lamp having a vapor or gas path, which consists in heating the gas or vapor, by the passage of the electric current therethrough, to such a temperature that the region of greatest conductivity is between the axis of the path and the circumference thereof, and producing a rate of heat radiation equal to that of the heat development at a predetermined temperature.

2. The method of producing light by the passage of current through a gas or vapor path, which consists in generating heat by the passage of electric current through the vapor or gas path, thereby modifying the density of the vapor or gas, and maintaining that density at the required degree by radiating heat therefrom at the same, or approximately the same, rate as heat is developed therein by regulation of the surroundings.

3. The method of controlling the resistance of an electric lamp having a Vapor or gas path and a definite heat-radiating capacity, which consists in passing current through the vapor or gas path thereby generating heat, and radiating the heat thus developed at such rate as to maintain the temperature and thereby the vapor density at a predetermined degree.

4. The method of controlling the resistance of an electric lamp having a Vapor or gas path and a definite heat-radiating capacity, which consists in passing electric current through the gas or vapor in such quantity as to develop heat within the limits of the heat-radiatin g capacity of the lamp, and thereby maintaining the temperature and the vapor density at a predetermined degree.

The method of controlling the resistance of an electriclamp having a vapor or gas path, and a definite heat-radiating capacity, which consists in mutually correlating the current flowing and the heat radiated by the lamp so as to maintain a predetermined vapor or gas density in the conducting-vapor, whereby the rate of heat radiation from the lamp is made dependent upon the resistance offered by the vapor or gas path, to the current flowing.

6. The method of operating electric gas or vapor lamps of the character described, which consists in governing the resistance of the lamp by the density of the vapor or gas path, governing that density by the temperature thereof, and governing such temperature by the heat-emissive capacity of the lamp.

'7. The method of operating a gas or vapor lamp of the character described, which consists in governing the current flowing therethrough by the resistance of the lamp, governing the resistance by the vapor temperature, and controlling the vapor temperature by the heat radiation of the lamp.

8. The method of controlling the current flowing through a gas or vapor lamp of the character described, which consists in controlling the temperature of the lamp by predetermining the heat radiating capacity, thereby controlling the density of the gas or vapor path and thereby controlling the resistance of the gas or vapor path, whereby the current flowing is controlled at definite voltage.

9. The method of controlling the varying resistance of a vapor carrying current, which consists in maintaining the heating efiect of the current approximately constant by means of varying the heat-abstracting power of the surroundings in direct ratio to the current passed.

10. The method of varying the current passed by an inclosed vapor passing current at Constant voltage, which consists in varying the heat-abstracting power of the surroundtained gas or vapor that the cooling effect of the chamberwill equal the heat-absorbing capacity of the gas or vapor for a determined temperature. 1

12. The method ofproducing and maintaining light by the passage of electric current through a gas or vapor path, which consists in confining the gas or vapor within definite limits suited to the density to be maintained, modifyingthe density of the gas or vapor by the passage of the current until a suitable operating density is obtained, and maintaining the density at the required degreeby radiating heat from the gas or vapor at the same or approximately the same rate as heat is developed therein ata definite temperature.

13. The method of producing and maintaining light by the passage of electric current through a gas or vapor path, which consists in heating the gas or vapor by the passage of the current and thereby modifying the density until a suitable operating temperature isobtained, and maintaining such density by giving to the lamp a capacity for radiating heat from the gas or vapor at approximately the same 'rate as heat isdevelo'ped therein at said temperature.

14. The method of adapting a gas or vapor to pass electric current on a constant-potening light by the passage of electric current through a gas or vapor path, which consists in developing heat by the passage of thecurrent through the gas or vapor and nullifying or offsetting the heat developed by the passage of the current after the limit of efficient 1 operation has been reach-ed by the radiation of heat at anequal rate through a proper di- 5 me'nsioning and disposition of the surround-- ing parts.

16. The method of producing and maintaiu- 3 ing light by the passage of electric current at definite voltage through a gas or vapor path f "which consists in first confining the gas or vapor within a container of appropriate heat- I radiating capacity; producing in the gas or vapor a density suitable for efficient working and then causing the thermal conditions Within the gas or vapor to operate automatthe density selected. Y

ically in opposition to anabnormal change of:

1.7. The method of'controlling the resist-k ance of a gas or vapor lam p'for increasing or decreasing the lightingcapacity of the lamp, which consists in varying the heat-abstracting capacity of thesurroundings of thelamp andtherebyvaryingthecurrentconsumption.

18. The method of producing light, which consists in inclosing a gas or vapor within such limits as to predetermine its normal density as suited to a definite current, andrende'rin'g the vapor light; radiant by the passage of electric current to which it is'adapted.

- 19. The method of producing light,which consists in inclosing a vapor-producing material within such limits as to predetermine the normal density as suited to a definite current, creating a vapor from such material by heat, and rendering the saidvapor light m.

diant by the electric current to which. it is' adapted.

20. The method of producinglightywhichconsists in in'closing a vapor within such limits as will produce a normal density adapted to give it a definite lowresistance, and passing through such vapor, as the sole conducting medium, acurrent of electricity of considerable quantity and of a voltage adapted to the resistance of the vapor.

21. The method of producing light, which within such limits as willgive to the produced vapor a normal density adapted to produce low resistance, passing an electric current through the said agent to firstproduce vapor of the normal density from it and thenbringing said vapor into a light-radiant condition by means of electricity.

23. The method of producing light, which consists in inclosing a volatilizable substance within such limits as Will cause the vapor produced therefrom to be of a density near its point of lowest resistance to an electric current, subjecting the substance to heat and thereby developing vapor, and passing into the Vapor an electric current of low voltage.

24. In the production of light, the method of removing vaporous impurities from a light-' radiant inclosur-e, whichconsists in volatilizin g an inolosed vapor-producin g agent by the passage of an electric current, and permitting the vapor so formed to drive vapor-ous, impurities in the inclosure to a pointoutside the influence of the current.

v25. The method of causing an incipient IIO ' the vapor in a container of predetermined dimensions with respect to the current and so having a definite heat-radiating capacity, and causing the current to create varying densities in different parts of the container due to the heating effect of the current.

27. The method of controlling the current passed at constant voltage by a vapor carrying current, which consists in inclosing the vapor, passing current therethrough, thereby developing heat therein, and so adjusting the surroundings that-the density of the vapor carrying current in different parts of the container Will vary With variations in the crosssection of the vapor traversed by the current.

28. The method of securing the control of the current passed. by a conducting-vapor at constant voltage, which consists in limiting the cross-section and length of the conducting-vapor, thereby predeterinining the heatradiating capacity of the apparatus, and causing the resistance of the vapor to vary by reason of the ratio of the heat generated by the current to the rate of heat radiated by the Vapor to the surroundings.

Signed at New York, in the county of New York and State of New York, this 24th day of January, A. D. 1901.

PETER COOPER I'IEVIT".

\Vitnesses:

WM. H. CAPEL, GEORGE II. STocKBnmoE.

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