GB413269A - Electric indicating control systems - Google Patents

Abstract

413,269. Gauging - apparatus. BARON, H., 231, Strand, London.-(Fitzgerald, A. S.; 433, Warwick Road, Wynnewood, Pennsylvania, U.S.A.) Dec. 6, 1932, No. 34584. [Class 106 (ii).] The distance between two relatively movable objects is indicated or controlled by the current produced as the result of light from one of the objects falling on a photo-electric system on the other. The arrangements may be duplicated in such a way that the distance is measured by the ratio of one current to the other and this ratio may be expressed as a single current by means of a bridge of saturable re-actors. The invention is described as applied to an elevator indicating system. As shown in Fig. 1, lamps 7<1> and 8 mounted at the bottom and top of an elevator shaft act on cells 9<1> and 10 mounted below and above the car so that the photoelectric currents produced vary with the position of the car in the shaft. Alternatively lamps 7 and 8 mounted at the top of the shaft may act on cells 9 and 10, the beams from the lamps being divergent and convergent respectively. To prevent interference the lamp 7 and cell 9 may be connected to the opposite phase to lamp 8 and cell 10 as shown in Fig. 2. The currents produced may be fed to ratio-type indicating instruments or may be fed through amplifiers 11 and 12 to re-actors 15 and 16 which are in a bridge with re-actor 17 and inductance 18. When the bridge is balanced no current flows in transformer 34 and, by means of the valve circuit shown, the current in winding 20 is adjusted to maintain the balance, this current being fed through indicating instruments 21, 22, 23, 24 in series which are calibrated to indicate the position of the lift. Specifications 400,206, [Group XXXV], 411,831, [Group XXXVIII], and (in the Provisional Specification) 404,034, [Group XXXVI], are referred to.