GB441881A - - Google Patents

Abstract

441,881. Electric signalling systems. AUTOMATIC ELECTRIC CO., Ltd., Strowger Works, Liverpool, RAYNER, T. R., 2, Stretton Avenue, Wallasey, Cheshire, and BURNS, G. A., 32, Score Lane, Broadgreen, and WOODHEAD, H. S., 23, Watergate Lane, Woolton, both in Liverpool. July 27, 1934, Nos. 22002 and 29501. [Class 40 (i)] In a system for transmitting to a distance information such as meter readings, a photoelectric cell, adapted to operate the receiving instrument, is illuminated intermittently by impulses of length proportional to the information to be transmitted. As shown, a meter spindle 2 carries a vane 1 which is rotatable so as to obscure more or less of the area of a mirror 3 from light rays received from a source 9 via the optical system 7, 8. The system 7, 8 is supported on an arm 5 driven by a motor 6 and the rotating light falling on the mirror 3 is interrupted by a toothed member 4 to form light impulses which influence the photo-electric cell 10 during the passage of the beam over the unobscured portion of the meter range. Two arms 5 and systems 7, 8 are employed to facilitate continuous scanning, further arms being utilized if desired, provided the range of meter movement is adjusted accordingly. The current interruptions generated by the photo-cell are amplified and applied to the line wires and at the receiver are rectified by a valve, the anode circuit of which includes a highly-damped ammeter in series with a high resistance and shunted by a condenser. The effects of stray currents in the line wires may be eliminated by employing a three-electrode neon tube in the grid circuit of the receiver rectifier. A number of meter readings may be transmitted simultaneously by utilizing different frequencies of current interruption which may be effected either by interrupting the light beams or by employing a circuit interrupter in series with the photo-cell. The indications of several meters also may be summated, the meters being connected in turn to the line by a distributer ; alternatively, the anode circuits of corresponding receiving valves may be fed through a common ammeter. In a modification, a line of light, the length of which is proportional to the meter reading is scanned by a photo-electric cell. Specifications 441,881 and 441,999 are referred to.