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Capacitively Coupled Contact

IP.com Disclosure Number: IPCOM000074090D
Original Publication Date: 1971-Mar-01
Included in the Prior Art Database: 2005-Feb-23
Document File: 2 page(s) / 29K

Publishing Venue

IBM

Related People

Collins, JF: AUTHOR

Abstract

Fingerstock material is usually located in a housing which is attached to a machine or a cover. The structure to which the housing is attached must provide electrical contact therebetween. Accordingly, the structure is usually plated with a conductive plating metal. The door or other structure, when closed, will contact the fingerstock and provide an electrical path between the door, the fingerstock and the structure to which the fingerstock is attached. This arrangement provides the necessary shielding.

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Capacitively Coupled Contact

Fingerstock material is usually located in a housing which is attached to a machine or a cover. The structure to which the housing is attached must provide electrical contact therebetween. Accordingly, the structure is usually plated with a conductive plating metal. The door or other structure, when closed, will contact the fingerstock and provide an electrical path between the door, the fingerstock and the structure to which the fingerstock is attached. This arrangement provides the necessary shielding.

This arrangement provides a channel 10 which holds the fingerstock 12 in place. The channel is attached to a machine frame or structure 14 which has a painted surface 16 rather than plated. The paint does not have to be a conductive paint. This forms a capacitor made up of the fingerstock channel, the paint, and the metal frame. The capacitor is shorted out by the mounting screws 18 for the channel. Instead of detracting from the operation, the arrangement is essential to shielding effectiveness at the higher-frequency ranges. As the frequency of the input signal to the cover (unwanted radiation) is increased, the impedance of the screw contact is increased (inductive reactance). This ordinarily causes the cover to radiate energy from the edges thereof. However, because of the capacitive coupling between the channel 10 and frame, the total reactance (X(L)-X(C)) remains small. That is, the increase of inductive reactance through the sc...