GB1321212A - Magnetic compass - Google Patents

Abstract

1321212 Magnetic compass LAITRAM CORP 2 March 1972 [28 April 1971] 9861/72 Heading G4H [Also in Division G1] A magnetic compass having a photo-electric indicating arrangement comprises an enclosure 20 housing a magnet 38 and rotor 36 which are pivotally mounted in a frame 44 suspended by a gimbal arrangement. The rotor 36 to which the magnet 38 is attached comprises a disc or drum provided with parallel tracks defining an opaque /transparent encoding scale having a clock track for use with photo-electric detectors 56 to 61 and a light source 54 whereby a digital electric signal indicative of the angular position of the magnet 38 relative to the enclosure 20 can be obtained. Electrical connections for the detectors 56 to 61 and the light source 54 are effected by way of a cable 78 inserted through an aperture 32 in the wall of the enclosure 20 and sealed thereto by a stuffing box 34. The enclosure 20 may be filled, except for an air space 76 to allow for expansion, with water or a water, ethanol mixture and may be in two hemispherical parts 21, 22 which are sealingly secured together. A radially extending post 30 may provide a mounting for the gimbal arrangement defined by pivot - ally connected members 64, 68 to which the frame 44 is pivotally attached. The frame 44 which may support the photo-electric detectors 56 to 61 and the light source 54 provides bearings 42, 43 which engage pivot pins 40, 41 secured to a rigid assembly defining the rotor 36 and magnet 38. The compass may be electrically connected to a digital read-out device or a steering control device. The digital signal can be corrected for magnetic variation.