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...http://www.google.com.au/patents/US4809044?utm_source=gb-gplus-sharePatent US4809044 - Thin film overvoltage protection devices
