inflated pneumatic, electrical light emitting roehre, which is filled with a vaporizable metal roehre in the longitudinal direction and a surrounding or by train passing through channel has

摘要

381,609. Discharge lamps. BRITISH THOMSON-HOUSTON CO., Ltd., Crown House, Aldwych, London, and DAVIES, L. J., 147, Murray Road, Rugby. Jan. 27, 1932, No. 9474/31. [Class 39 (i).] Discharge lamps for advertising and beacon lights &c. contain metal vapour such as mercury and one or more gases such as neon in proportion to produce a discharge characteristic of the vapour or gas according to the temperature of the container or part thereof, this temperature being regulated by varying the flow of a cooling medium over the container. A cylindrical container 3 with a graphite anode 4 and an indirectly heated cathode 5 of the vane type is provided with a thinned portion or pip 6 subjected to a jet of cool air flowing through a tube 7 when hot air due to the heat of discharge rises in an outer chimney 2. When a shutter 8 is open, the mercury vapour pressure in the container 3 is low and a red discharge is obtained. When the shutter is closed, the jet of air is stopped and a blue mercury discharge spreads up from the cathode with a clear line of demarcation between the red and blue, until the blue discharge fills the tube. The shutter 8 may be operated manually or automatically under the control of two photo-electric cells sensitive to red and blue respectively and positioned opposite different points of the container 3. Alternatively, the shutter may be operated by a magnet excited partly or wholly by current proportional to the voltage drop across the electrodes-4, 5. In a modification, the container is annular to form an inner chimney with a constriction near the lower end. A flap at the bottom of the chimney controls the flow of air, and the electrodes may be mounted in the annular container or in side chambers.