US1969765A - Lighting device - Google Patents

Description

Aug. 14; 1934. J. SPANNER ET AL 1,969,765

LIGHTING DEVICE Filed April 50. 1929 3 5 52 4%.; 5 /62 aa-sg 62 INVENTORS Ham JJp /pwr vUlric/L Doe/fag Y gmyc fivww ATTORNEYS Patented Aug. 14, 1934 UNITED STATES LIGHTING DEVICE Hans J. Spanner, Berlin, Germany, and Ulrich Doering, New York, N. Y., assignors, by mesne assignments, to said Hans J. Spanner Application April 30, 1929, Serial No. 359,330 In Germany September 24, 1928 3 Claim.

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. Heretofore such tubes have generally operated with cold electrodes and because of the voltage consumed at the cold cathode the tubes have been made of considerable length, three or four meters long or even longer. Such lengths are awkward to 1 handle, the tubes require high voltage transformers, and they are undesirable for many reasons. Some effort has been made to operate such devices with glowing and emitting cathodes, but the limitation in such cases is the other way, one

to one and one-half meters being the maximum length in which they can be readily constructed for operation direct from a low voltage supply circuit.

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 different embodiments thereof taken in connection with the accompanying drawing in which Fig. 1 is a longitudinal elevation partly in section of a discharge device, the external connections being shown in diagrammatic form;

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

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

The reference character 11 indicates a glass tube having electrodes 12 and 13 positioned in the ends thereof. These electrodes are preferably of a glowing and emitting type and may be maintained at a temperature sufilciently 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, caseium and rubidium either in metallic form or as compounds. Among the compounds suitable for the purpose may be mentioned phosphates and double silicates. The emissive substance may have associated therewith an amphoteric compound such as aluminum oxide or zirconium oxide which gives greatly increased resistivity to disintegration. These electrodes are connected through leading-in wires 14 and 15 to conductors 16 and 1'? of a suitable supply circuit. Current limiting or ballast impedances 18 and 19 are connected in the conductors 16 and 17 to give to the tube suitable operating characteristics, the gaseous discharge path alone having a so-called negative temperature characteristic. Auxiliary electrodes 20 and 21 may be positioned adjacent to the electrodes 12 and 13 respectively, and are connected to the conductors 17 and 16 respectively through high resistances 22 and 23. The ends of the tube where the electrodes are positioned have a ground glass surface as indicated at 24 and 25, or an opal flashed surface, or the glass may be opal throughout its entire thickness, or the glass may be given light diffusing characteristics in any other suitable manner. Also the glass of the tube may have these light diffusing characteristics throughout its entire length. By these means the illumination, which is of a non-uniform intensity around the electrodes, is diffused and the tube as a whole appears to have a uniform illlumination throughout. For obtaining special effects 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 an electrode 12 and the auxiliary electrode 20 at one end of the tube and between the main electrode 13 and the auxiliary electrode 21 at the other end of the tube. Because of the high value of the resistances 22 and 23, the current flow through 35 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 12 and 13.

In the form shown in Fig. 2, electrodes 31 and. 32 are positioned in the ends of the tube 11 and other electrodes such as 33 and 34 are positioned in intermediate positions in the tube. The electrode 31 has a leading-in wire 35 connected to a line conductor 36 controlled by a switch 37. 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 41 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 31, 33,

34 and 32 may have positioned adjacent thereto auxiliary electrodes 44, 45, 46 and 47 respectively. Each of these electrodes has a. leading-in wire 48, 49, 50 and 51 which is connected in each instance to the opposite line conductor from that to which its atfiacent main electrode is connected. The

portion of the tube surrounding and near the electrodes is of some suitable light diffusing character, such as ground glass or opal flashed glass as indicated at 52.

In operation, the line switch 37 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 31 to the electrode 32, all the gas discharge paths 3l-33, 33-34, and 34-32 being in series. The light diffusing character of the glass near the electrodes, as indicated at 52, prevents the irregularities in the intensity of theillumination at these portions of the tube from reaching the eye of the observer and, to all practical intents and purposes, the tube is uniformly lighted from one end to the other.

In the form shown in Fig. 3, the tube 11 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 57 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 61 and these leading-in wires are connected to the conductors 58 and 59 of the supply circuit, adjacent electrodes being connected to the opposite conductors.

Each leading-in wire 61 is provided with a high impedance 62, 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 to each 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 67, 68 and 69.

The resistances of the coils 67, 68 and 69 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 sufficient or even preferable under a given set of conditions. The glass throughout may be of light diffusing characteristics, or the portions surrounding and near to the electrodes, as indicated at 70, may be ground or opal flashed to give the tube, as a whole, the appearance of being uniformly illuminated.

In the operation of the form shown in Fig. 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 63, or to a portion of one of the conductve coils connecting the electrodes. The conductive coils 67 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 may be suiiicient.

It will be seen from the foregoing description that simple and efiective means have been provided for such devices which enable them to be formed readily into letter and into special bent and angular forms. no

The form and construction of the discharge tubes as shown in the drawing is intended only to be exemplary, and it will be understood by those who are skilled in the art that numerous changes can be made without departing from the scope of the present invention.

We claim:

1. A gas discharge fighting device for operation directly from a low voltage supply circuit comprising an inclosing tube of glass and a plurality of electrodes positioned therein, a portion of said glass adjacent the electrodes being of a light diffusing character.

2. A gas discharge lighting device for o tiondirectly from a low voltage supply circuit comprising an inclosing tube of glass, a plurality of auxiliary chambers of glass extending laterally from said tube, and an electrode positioned in each of said chambers, the glass around said electrodes being of a light diffusing character so that the tube appears to be uniformly illuminated.

3. A gas discharge lighting device for operation directly from a low voltage supply circuit comprising an inclosing tube of glass and a plurality of electrodes positioned in said tube, at least one of said electrodes being positioned in an intermediate position in the path of the gaseous discharge, the glass around said intermediate electrode being of alight diffusing char- 4o acter so that the tube appears to be uniformly illuminated.

HANS J. SPANNER. ULRICH DOERING.

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