Patent GB-419937-A (GB)
Title: Improvements in and relating to electrical display devices
IPC: H05B41/24
Filed: 1933-02-18
Abstract: 419,937. Discharge lamps ; signs. LEBEDENKO, N., 10, Holsteinische Strasse, LEVY, R., 125, Rudolstaedterstrasse, both in Wilmersdorf, and ZEITLIN, W., 19, Oranienstrasse, both in Berlin. Feb. 18, 1933, No. 5107. Convention date, Feb. 9, 1932. [Class 39 (i).] A discharge lamp is energized by means of high-frequency currents and is provided with main internal or external electrodes, some of which are constructed as signs, and with external auxiliary electrodes to which potentials are applied for controlling the colour or intensity or the spatial distribution of the discharge. A discharge lamp 34, Fig. 5, in the form of a Dewar vessel, comprises sign electrodes 35, 36 and an auxiliary electrode 38, which are connected through a battery 35<a>, resistance 37 and a Tesla coil 12 to a highfrequency generator which comprises a thermionic valve 1, a gas-filled discharge tube, a magnetron or a spark gap. The high-frequency oscillations may be modified by low-frequency or speech oscillations, e.g. the reaction coil 7 may be connected to a discharge lamp 10 which is connected in parallel with a condenser 8 and a variable resistance 9, or by coupling the circuit to an alternating-current source through a coil 33. A switch 11 on the circuit of the lamp 10 may be replaced by a time switch in the anode or cathode-heating circuit. It is stated that the lamp may act as a sound reproducer due to acoustic oscillations of loosely inserted electrodes and of the glass container. The discharge may be modified by means of tapped condensers or switches 18, 19, 26, 25 and. the variable condenser 24 and by the use of an adjacent pendulum which is connected to earth. The centre contact of the switch 26 is connected to the electrode 38 through an inductance 31, condenser 30 and a resistance 32 all of which are variable. A feeler 39 may be adapted to modify the discharge and to control a loud-speaker in accordance with the movement of surrounding bodies. In a further modification, a coil 46, shunted by a variable resistance 48, is variably coupled to the transformer 12 by means of a spring 45 and a moving support 44. Undesirable low-frequency currents may be detected stroboscopically by means of a discharge lamp 41 which is mounted on an oscillating steel spring 42 so as to contact periodically with the ends of a coil 40 coupled to the Tesla coil. In further modifications, the main and auxiliary electrodes are connected to tappings on the secondary of the transformer 12, or a point on the said tappings, or the auxiliary electrode, is earthed. The switches 18, 19, 26 may be replaced by variable inductances or condensers which may be mechanically coupled together. An electrode holder adapted to be inserted in the lamp is formed of a material known under the Registered Trade Mark of " Pertinax." The electrode signs are mounted through a layer of black velvet on a removable portion 72, Fig. 15, and are connected through springs 78 to terminal rods 73<a>. Alternatively, the springs 78 are connected through metal sheets 73b to leads 78a. The auxiliary electrodes are formed by the cylindrical member 74 which may be divided into rings insulated from one another. The sign electrodes may consist of polished zinc sheet on which are provided patterns in relief, or are suitably shaded by means of shellac. The lamp may consist of a flattened tube, a sphere, or an ellipsoid. In another form, the sign electrodes are carried upon the exterior or the interior of a double-walled cardboard or Pertinax tube which is embraced by the auxiliary plate electrode and is provided internally with leads and connections.