GB1384528A - Scanner units - Google Patents

Abstract

1384528 Electromagnetic relays; selector switches SOLARTRON ELECTRONIC GROUP Ltd 19 June 1972 [19 June 1971 28 Dec 1971] 28891/71 and 60262/71 Heading H1N A scanner unit for selectively connecting analogue signals to a measuring instrument comprises a plurality of reed relays having reed units mounted externally of their energizing coil, the relay coils being connected to the conductors of one printed circuit board and the contact units being connected to the conductors of a second printed circuit board. Each reed relay comprises a coil 10 having plate like polepieces 16 extending perpendicularly to the coil axis and mounted at opposite ends thereof, each polepiece having a first bent over portion 26 extending into the coil 10 and a second bent over portion 28 extending parallel to the coil axis and towards the second bent over portion 28 of the other polepiece, the first bent over portions 26 overlapping within the coil 10 and being a pushfit therein, and a sealed magnetic reed contact unit 30 mounted outside the coil about an axis parallel to and adjacent the line joining bent over portions 28. Each polepiece 16 is H-shaped as shown, although the upper portions 22 of the legs 18 could be omitted. The lower ends 20 of legs 18 are of reduced cross-section for mounting on a printed circuit board 21 to which the coil 10 is electrically connected. A further printed circuit board 38 spaced from the first board 21 by the polepieces 16 carries four contact units 30 of the relay and each unit 30 is electrically connected in series with a respective conductive track of the board 38. The reeds are nickel iron reeds with diffused gold contacts. The junctions between the contact units 30 and conductive tracks on board 38 are shielded from air currents by a polystyrene shield 70 provided with cavities 72 to receive the junctions. A plurality of reed relays are mounted between the printed circuit boards 21, 38 to form a scanner in which a plurality of analogue input signals from remote transducers are sampled at selected time intervals. A manual selector is also provided to energize any relay at any time to sample the analogue signals. The polepieces and core may be replaced by a one piece moulding of plastics loaded with ferromagnetic material.