| 摘要 |
PURPOSE:To make possible the provision of electrodes in the state of having no cracks by providing a heating layer which has a positive resistance temp. characteristic (PTC) after calcination and on which the electrodes are formed in the axial direction of a roller. CONSTITUTION:The electrodes 5A, 5B are formed to a mixture composed of raw material and binder prior to the calcination to obtain the PTC characteristic. The mixture is calcined at a high temp. in succession to such formation by which the electrodes and the mixture are united. The heating layer 4 is the PTC ceramic layer provided as an upper layer of an inside surface layer 7 and constitutes the layer of the resistance lower than the resistance of the ceramics of the layer 7. Conductors 5A, 5B are alternately and successively printed at approximately specified intervals on the inside of the layer 4. The conductors 5A, 5B form the line-shape pattern relative to the longitudinal direction over the entire part of the longitudinal direction of the layer 4. The dimensional deformation and cracks are thus obviated and the excellent temp. distribution is obtd. |
