GB394768A - Improvements relating to indicators for use in mimic circuits or like diagrams - Google Patents

Abstract

394,768. Electric signalling systems ; indicators. INTERNATIONAL GENERAL ELECTRIC CO., Inc., 120, Broadway, New York, U.S.A. - (Assignees of Allgemeine Electricitõts- Ges.; 2, Friedrich Karl-Ufer, Berlin.) March 15, 1932, No. 7698. Convention date, March 16, 1931. [Class 40 (i).] An indicator for use in mimic circuit diagrams comprises a parabolic reflecting surface 6 adapted to reflect external light through a prismatic refractor 5 under the control of an electromagneticallyoperated shutter 7. The refractor is arranged behind a transparent cover-plate 4 and is adapted to throw the rays of light, irrespective of their angles of incidence on to the reflector 6 in such a manner that they emerge in a parallel beam. By the use of this arrangement the ordinary illumination provided in front of the mimic diagram is sufficient to provide clear indications. The shutter 7 is operated by an electromagnet 9 which is controlled in accordance with the condition of the associated apparatus unit. To avoid the necessity of maintaining the coil 9 energized, an electromagnetically-operated pawl may be provided to retain the shutter in its raised position. The shutter and refractor preferably are of complementary colours so that according to the position of the shutter the conditions of the apparatus unit may be distinguishable by the different colours as well as the different conditions of illumination. The indicator is located in a line circuit diagram represented at 3.