GB1132842A - Improvements in or relating to instrument type electrical relay devices - Google Patents

Abstract

1,132,842. Indicating apparatus. SANGAMO WESTON Ltd. Feb.8, 1966 [Feb.11, 1965], No.6028/65. Heading G1J. An instrument type relay, of the kind in which deflection of the instrument movement varies the illumination of a photo-cell whose electrical output controls a switching mechanism, incorporates a light source and an associated light guide in the form of a flat plate from which light emerges in a direction perpendicular to the plate surface. The instrument has a pivotal movement whose pivotal axis is perpendicular to the light guide plate, and the movement carries a shutter which moves in a plane parallel to the plate. The pivotal moving coil 10 carries an arcuate shutter 11 which moves in its own plane and parallel to the plane of the light guide plate 21. The latter is of a light transmitting material such as Lucite (Registered Trade Mark) and is internally illuminated by means of an electric lamp 22 contact to which is made by way of terminals 32, Fig. 5 (not shown) to conductive foil sheets on the plate surface. The light thus produced inside the plate 21 emerges through an arcuate strip 19 which is in the path of the shutter 11, as indicated by the arrow-headed broken line in Fig.2. The photo-cell is a photo-resistive element 17 carried by a member 16 which pivots about the axis x of the moving coil and can be set to a required position, indicated by the setting pointer 14. When the instrument pointer 12 becomes aligned with the setting pointer 14, the shutter 11 obscures the light path from strip 19 through cylindrical lens 18 to the cell 17 and thus gives the relay signal. A second settable pointer and associated photo-cell may also be provided Fig.1 (not shown). Each photo-cell is connected in a transistor amplifier circuit Fig. 6 (not shown) whose output operates a contact-making relay.