| 摘要 |
PURPOSE:To prevent a current from flowing to the local overheat portion of an electrode from the non-local-overheat portion by forming one or more slits on a metal layer inserted between a positive-resistance temperature coefficient characteristic layer and a planar heating element. CONSTITUTION:Belt-shaped electrodes 12 are fixed at both side edge sections of a planar heating element. The electrode 12 has metal layers 14, 15 made of a metal thin piece such as a copper foil on both the upper and lower faces of a polymer layer (positive-temperature coefficient characteristic layer) 13 made of a PTC polymer composition material. Multiple slits 16 are formed along the lateral direction of the electrode 14 on the layer 13 and the lower metal layer 15. These slits 16 function as nonconducting portions of the metal layer 15, and the metal layer 15 is divided into multiple conducting portions When part of a planar heater is heat-isolated and its temperature rises for a local overheat, a current can be prevented from flowing to the local overheat portion of an electrode from the non-local-overheat portion. |
