US2097261A - Lighting device - Google Patents

Description

Oct. 26, 1937. H, SPANNiER 2,097,261

LIGHTING DEVICE Original Filed April 150, 1929 Jay 6 5 a i 0.0... .0000 5 4. 4 1 55 'l 2 53 933 53 13511 5? 53 {J mm, 57 M Jim up". 64 mm-u 56 k 6/ 6/ I 57 5e 2/ 64 62 e0 W/ I 62 Patented Oct. 26, 1937 UNITED STATES PATENT OFFICE LIGHTING DEVICE Hans Joachim Spanner, Berlin, Germany 11 Claims.

This application is a division of the application Serial No. 359,330, filed by applicant and Ulrich Doering on April 30, 1929, and on which Patent No. 1,969,765 was granted August 14, 1934.

This invention relates to gas discharge devices, especially to those devices in which a gas discharge takes place in a glass tube and which are suitable for illuminating purposes. More particularly the invention relates to such devices which operate with glowing and emitting cathodes.

The present invention has for its object the production of a satisfactory gas discharge device suitable for operation directly from a low voltage supply circuit. In order to more clearly explain the invention, reference is made to the following description of difierent embodiments thereof taken in connection with the accompanying drawing in which Figure 1 is a longitudinal elevation partly in section of a discharge device, the external connections being shown in diagrammatic form;

Figure 2 is a longitudinal section of another form of gas discharge device with special means for changing from starting to running operation; and

Figure 3 is a longitudinal section of still another form of gas discharge device.

The reference character N indicates a glass tube having electrodes l2 and I3 positioned in the ends thereof. These electrodes are preferably of a glowing and emitting type and may be maintained at a temperature sufiiciently high ,to give the desired emissivity by the heating action of the gaseous discharge itself. As examples of substances suitable for rendering the electrodes highly emissive may be mentioned barium, strontium, calcium, caesium and rubidum either in metallic form or as compounds. Among the com- 40 pounds suitable for the purpose may be mentioned phosphates and double silicates. The emissive substance may have associated therewith an anhydride of an amphoteric compound such as aluminum oxide or zirconium oxide which gives 45 greatly increased resistance to disintegration.

These electrodes are connected through leadingin wires l4 and I5 to conductors l6 and ll of a suitable supply circuit. Current limiting or ballast impedances l8 and H! are connected in the conductors l6 and H to give to the tube suitable operating characteristics, the gaseous discharge path alone having a so-called negative characteristic. Auxiliary electrodes 20 and 2| may be positioned adjacent to the electrodes l2 and I3 55 respectively, and are connected to the conductors H and I6 respectively through high resistances 22 and 23. For obtaining special efiects fluorescing glass such as lead glass or scandium glass may be employed.

In operation, the line switch is closed and thereafter a discharge is set up between the main electrode l2 and the auxiliary electrode 20 at one end of the tube and between the main electrode I3 and the auxiliary electrode 2| at the other end of the tube. Because of the high value of the resistances 22 and 23, the current flow through these discharge paths of short length is limited and the discharge is transferred for the most part to the path which lies between the two main electrodes l2 and i3.

In the form shown in Figure 2, electrodes 3| and 32 are positioned in the ends of the tube ii and other electrodes such as 33 and 34 are positioned in intermediate positions in the tube. The electrode 3| has a leading-in wire 35 connected to a line conductor 36 controlled by a switch 31. The electrode 32 has a leading-in wire 38 connected to a line conductor 39 in which is inserted a current limiting resistance 40. The electrode 33 has a leading-in wire 4| which is connected through one side of a double pole switch 42 to the line conductor 39 and similarly the electrode 34 has a leading-in wire 43 which is connected through the other side of the double pole switch to the line conductor 36. The electrodes 3|, 33, 34, and 32 may have positioned adjacent thereto auxiliary electrodes 44, 45, 46, and 4'! respectively. Each of these electrodes has a leading-in wire 48, 49, 50, and 5| which is connected in each instance to the opposite line conductor from that to which its adjacent main electrode is connected.

In operation, the line switch 31 is closed and also the double pole switch 42. This places substantially the full line potential across adjacent main electrodes. Also substantially full line voltage is impressed between each main electrode and its adjacent auxiliary electrode. Because of the shorter distance between each main electrode and its auxiliary adjacent electrode, the discharge is first set up through these short paths, but because of the high resistance in series with these discharge circuits the discharge almost immediately passes over to the longer path between adjacent main electrodes. After the tube is operating, the switch 42 may be opened and the discharge thereafter passes from the electrode 3| to the electrode 32, all the gas discharge paths 3|--33, 33-34, and 34-32 being in series.

In the form shown in Figure 3, the tube H is provided with a plurality of chambers 53 extending at right angles from the main tube so as to be out of the main discharge path within the tube and in each of these chambers is positioned an electrode which may comprise an outer emissive coating or shell 54 within which is positioned a heating coil 55. Each heating coil 55 has leading-in wires 56 and 51 which are connected to opposite conductors 58 and 59 of a supply circuit. A suitable resistance 60 may be connected in each heating circuit to limit the current flowing in the heating coil or, if preferred, the heating coil may be so designed that the resistance may be dispensed with and the full line voltage impressed directly on the heating coils. Each shell 54 is provided with a leading-in wire 6! and these leading-in wires are connected to the conductors 58 and 59 of the supply circuit, adjacent electrodes being connected tothe opposite conductors. Each leading-in wire 6| is provided with a high impedance 52, which may be resistance on direct current and resistance or inductance on alternating current, so as to give stability to a suitable current flow through the gaseous discharge path. To facilitate starting of the gaseous discharge, auxiliary electrodes 63 may be provided adjacent toeach main electrode. Each auxiliary electrode 63,has a suitable leading-in wire 64 connected through a high impedance 65 to the opposite side of the line from that to which the adjacent main electrode is connected. The operation of the tube may be controlled by a suitable line switch 66 in the conductor 59. The starting of the gaseous discharge may also be materially assisted by connecting adjacent electrodes by a conductive path, such as a filament of wire, which may be in the form of a coil or helix as indicated at 61, .58, and 69.

The resistances of the coils 51, 68, and 59 may be so chosen that the current drawn through the coils is very small but by a suitable arrangement and proportioning of these coils, the discharge may be caused to first start between an electrode and the adjacent portion of the coil, the discharge thereafter extending itself until it reaches from one main electrode to another. While both auxiliary electrodes and conductive connections between electrodes have been described as being of assistance in starting the discharge, it is to be understood that both are not necessarily employed in every discharge tube, as one only may be suftlcient or even preferable under a given set of conditions.

In the operation of the form shown in Figure 3, the shells of the electrodes are gradually heated by the passage of the current through the heating coils 55. The initial discharge first takes place either to an auxiliary electrode as 53, or to a portion of one of the conductive coils connecting the electrodes. The conductive coils 61 and 69 may be omitted, if desired, as the discharge readily starts in adjacent sections of the tube after it has been set up in the middle portion so that the conductive coil 68 in the middle section maybe sufiicient.

It will be seen from the foregoing description that simple and effective means have been provided for such devices which enable them to be formed readily into letter and into special bent and angular forms.

I claim:

1. In a radiant electrical discharge device which comprises an envelope permeable to at least a part of the radiation from the discharge,

an ionizable filling therein adapted to carry the discharge, a plurality of electrodes spaced apart therein, a cathode which comprises a metallic support and a coating thereon comprising an activating metal of the electropositive group Ba, Sr, Ca, Cs, Rb, in a silicate material given strength and resistance to disintegration by heating, and in which the activating coating also comprises a refractory amphoteric oxide besides the silica.

2. In a radiant electrical discharge device which comprises an envelope permeable to at least a part of the radiation from the discharge, an ionizable filling therein adapted to carry the discharge, a plurality of electrodes spaced apart therein, a cathode which comprises a metallic supportand a coating thereon comprising an activating metal of the electropositive group Ba, Sr, Ca, Cs, Rb, in a silicate material given strength and resistance to disintegration by heating, and in which the activating coating also comprises zirconium oxide.

3. In a radiant electrical discharge device which comprises an envelope permeable to at least a part of the radiation from the discharge,

an ionizable filling therein adapted to carry the discharge, a plurality of electrodes spaced apart therein, a cathode which comprises a metallic support and a coating thereon comprising an'activating metal of the electropositive group Ba, Sr, Ca, Cs, Rb, in a silicate material given strength and resistance to disintegration by heating, and in which the activation coating is formed from a double silicate of the activating metal. 1

4. In a radiant electrical discharge device which comprises an envelope permeable to at least a part of the radiation from the discharge, an ionizable filling therein adapted to carry the discharge, a plurality of electrodes spaced apart therein, a cathode which comprises a metallic support and a coating thereon comprising an activating metal of the electropositive group Ba, Sr, Ca, Cs, Rb in a phosphate material given strength and resistance to disintegration by heating.

5. In a radiant electrical discharge device as defined in claim 4 a cathode as therein defined in which the activating coating comprises i'ree metal of said electro-positive group.

6. A radiant electrical discharge device comprising an envelope permeable to at least a part of the radiation from the discharge, a gaseous filling therein adapted to carry the discharge, a plurality of electrodes spaced therein, and a spiral conductor between the electrodes, close to the wall of said envelope, surrounding the discharge.

7. A radiant electrical discharge device comprising an envelope'permeable to at least a part of the radiation from the discharge, a gaseous filling therein adapted to carry the discharge, a plurality of spaced electrodes therein, and a high resistance thermionic conductor connected between said electrode and extended for a substantial distance along and near the inner surface 01' tive to the principal electrode, than upon any 7 atoms:

part of said conductor which is equally near the principal electrode, whereby to protect said con-= ductor against injury by arcing from the principal electrode.

9. The combination of a radiant electrical discharge device comprising an envelope permeable to at least a part of the radiation from the discharge, a gaseous filling therein of material adapted to provide a gaseous atmosphere for the discharge, a plurality of electrodes positioned therein, at least two of which are far apart and at least two of which are positioned intermediate said first two along the path of the discharge, and means for energizing a discharge therein comprising a source of potential, means for connecting one side of said source to alternate electrodes and for connecting the other side of said source to the other alternate electrodes in the discharge device, and means in the connections to the intermediate electrodes for disconnecting said intermediate electrodes after the discharge is started, whereby the discharge may continue thereafter directly between the electrodes which are far apart.

10. A radiant electrical discharge device com prising an envelope permeable to at least a part of the radiation from the discharge, a filling therein adapted to provide a gaseous atmosphere for the discharge, a plurality of electrodes spaced therein, and a high resistance thermionic conductor extended along the space between the electrodes and adapted to be heated to thermionic temperature by the current passing therethrough, and a source of current in circuit with such conductor adapted to provide current sufllcient to heat the conductor to thermionic temperature and at a potential greater than the striking potential of ,a discharge between the ends of said conductor in the ionized filling, whereby the conductor upon reaching a temperature of thermionic emission sufiicient to ionize the gas automatically short circuits itself by initiating a discharge at lower potential in the gas.

11. A radiant electrical discharge device as defined in claim 10 in which one of the electrodes is an activated cathode and the thermionic conductor is connected to opposite electrodes, whereby substantially the full potential imposed on the principal electrodes for starting of the discharge is imposed upon the high resistance conductor andthe automatic short-circuiting of the con ductor by a discharge establishes the discharge immediately and directly between the principal electrodes.

HANS JOACHIM SPANNER.

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