Northern Telecom Limited

Robert J Boynton

Frederick Caldwell Livermore

David R Baraff

William D Westwood

Richard W Streater

Nur M Serinken

Carla J Miner

Blair K MacLaurin

A matrix multiplexed field effect display has switch devices at matrix crosspoints to provide a turn-on threshold for the field effect material. The switch devices are thin film metal-insulator-metal (MIM) switches. The display is operated at low current so that the MIM switches, which may be deposited on glass, do not degrade rapidly in use.

Displays controlled by MIM switches of small capacitance

In a thermal print bar for use in facsimile systems, an array of individually selectable electrical current paths are defined in a strip of resistive materials having a high negative temperature coefficient of resistance. In operation, the resistance of a selected current path is markedly reduced in contrast with the resistance of unselected current paths parallel to the selected path so that the parallel current paths do not experience joule heating. Electrical power saving and visual contrast result.

Thermal print bar

A thermal printing device comprises a continuous bar of electrically resistive material, with patterns of electrical conductors on each side of the bar. Connections are made to the bar from the conductor patterns at closely spaced positions. The conductor patterns are formed as columns on one side and rows on the other side to enable connections between columns and bar and rows and bar such that the number of external connections is minimized. The connections to the bar from the conductor patterns are staggered on one side of the bar relative to the other side. This doubles the center-to-center distance of such connections as correspond with connections which are opposite each other. This enables wider connection paths while still maintaining the original resolution.

Thermal printing device

A thermal printing bar, as for a facsimile printer, has a pattern of associated conductors on each side thereof to produce two rows of hot spots in the printing bar. The hot spots in one row are offset relative to the other row. By suitably sizing the hot spots, the spots in one row will at least completely fill the gaps between the spots in the other row, or can even overlap. By this means, the one row is first printed on the paper; the paper moved by the distance between the centers of the rows and then the other row printed. This provides contiguous or overlapping spots on the paper, giving improved contrast.

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Ottawa, Canada

Robert J Boynton