Electrical Composite Element
An electric device that functions either as a reverting (resettable) type element or a non-reverting (non-resettable) type element depending on the conditions. Such an element includes a polymer PTC element and a temperature fuse member connected in series thereto, the temperature fuse member placed such that it is under the thermal influence of the polymer PTC element. A melting point of a metal composing the temperature fuse member is at least 5° C. higher than a melting point of a polymer composing the polymer PTC element.
1 . An electric composite element comprising
(a) a polymer PTC element comprising a polymer having a melting point, and
(b) a temperature fuse member comprising a metal having a melting point, said temperature fuse member connected in series with the polymer PTC element,
said electric composite element is characterized in that the temperature fuse member is placed such that it is under the thermal influence of the polymer PTC element, and the melting point of the metal is at least 5° C. higher than the melting point of the polymer.
2 . The electric composite element according to claim 1 , characterized in that the melting point of the metal is at least 10° C. higher than the melting point of the polymer.
3 . The electric composite element according to claim 1 , characterized in that the melting point of the metal is at least 20° C. higher than the melting point of the polymer.
4 . The electric composite element according to claim 1 , characterized in that the polymer is an ethylene-vinyl acetate copolymer or an ethylene-butyl acrylate copolymer.
5 . The electric composite element according to claim 1 , wherein the polymer PTC element has an electrical resistance after its actuation that is at least 500 times its electrical resistance at normal temperature.
6 . The electric composite element according to claim 1 , wherein the temperature fuse member is at least partially covered by a resin layer.
7 . The electric composite element according to claim 1 , wherein the polymer PTC element is placed on an insulating substrate.
8 . An electric device comprising the electric composite element according to claim 1 .
9 . The electric device according to claim 8 which is a battery pack, wherein the electric composite element is placed on the outside of a casing of the battery pack.
10 . An electric apparatus comprising a battery pack according to claim 9 .
11 . The electric apparatus according to claim 10 which is a cellular phone device.
12 . The electric composite element according to claim 4 , wherein the polymer PTC element has an electrical resistance after its actuation that is at least 500 times its electrical resistance at normal temperature.
13 . The electric composite element according to claim 6 , wherein the polymer PTC element is placed on an insulating substrate.
14 . The electric device according to claim 8 , wherein the polymer is an ethylene-vinyl acetate copolymer or an ethylene-butyl acrylate copolymer.
15 . The electric device according to claim 8 wherein the polymer PTC element has an electrical resistance after its actuation that is at least 500 times its electrical resistance at normal temperature.