Electrical switching apparatus and energizing circuits therefor
AssigneeThe Solartron Electronic Group Limited
InventorsRobert J. Dalley, Robert D. Owen, George S. Parmenter
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Abstract
A scanner unit on a double-sided printed circuit board has reed switches on one face and coils on the other. The copper patterns include large screening pads beneath the reed switches and the coils. These pads distribute heat evenly along the switches to minimize thermally-induced E.M.F.'s, and provide electrostatic screening. An energizing circuit for the coils provides a single, long pulse several times larger in magnitude than the minimum required for relay actuation, followed by a series of shorter pulses of the same magnitude, but having a time-average magnitude equal to the relay holding current. This avoids the need for a voltage-dropping resistor and power wastage therein.
Claims13
Electrical switching apparatus for an electrical scanner unit, wherein a printed circuit board carries a plurality of reed relays each comprising an electric coil and at least one reed contact unit, wherein the coils are disposed on one surface of the board and the contact units are disposed on the other surface opposite their respective coils, and wherein screening means of substantially non-magnetic, electrically- and thermally-conductive material is disposed between each contact unit and its respective coil.
Dependencies are inferred from the claim text.