Thin film overvoltage protection devices
AssigneeEnergy Conversion Devices, Inc.
InventorsRoger W. Pryor, Napoleon P. Formigoni, Stanford R. Ovshinsky
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Abstract
Solid-state overvoltage protection devices, preferably formed of deposited thin film, chalcogenide, threshold switching materials, typically include at least one elongated current conduction path through an elongated cross-sectional area of the threshold switching material. The cross-sectional area is formed with a length far exceeding the effective width thereof for distributing the transient current produced by overvoltage conditions over a relatively large area. In this manner, the concentration of localized heating effects can be avoided.
Claims26
A solid-state overvoltage protection apparatus of the type having a plurality of spaced electrodes and a body of threshold switching material disposed therebetween, said body having a high electrical resistance to provide a blocking condition for substantially blocking current therethrough at operating voltages below a first nominal voltage level and a lower electrical resistance at overvoltages above said nominal voltage level to provide a conducting condition for conducting current therethrough, the improvement comprising in combination:
- means for providing an elongated current conduction path of substantially uniform distance between said electrodes through said body confined to an elongated cross-sectional area of said body transverse to the direction of current flow, said cross-sectional area having an effective length along the major dimension of said area which is at least about ten times greater than the maximum effective width of said area,
- whereby relatively large currents associated with overvoltages which may flow therethrough are distributable over said elongated area.
Dependencies are inferred from the claim text.