| 摘要 |
A large-area, thin film, resistance heating element (21, 46, 81) including a relatively rigid substrate (22, 63, 82), which will retain its mechanical properties at elevated temperatures, an electrically conductive film (26, 64, 84) deposited on the substrate (21, 46, 81), and electrical terminals (31, 66, 86) provided on the film (26, 64, 84). A metallic substrate (22, 63), such as a steel sheet, having an electrically insulating ceramic-based layer (23, 62, 83) thereon may be employed, or alternatively, a micanite plate or sheet (61) can be used. The substrate and film have an area which is sufficiently large that the heater can operate at maximum temperatures above 100 DEG F. with a power density less than about 15 watts per square inch. The electrically conductive film is preferably a metal-oxide film, such as tin-oxide, and is used as a resistance heater in applications such as ovens (41) and space heaters (81) to allow delivery of substantial power at lower operating temperatures and low power densities for greater efficiency. |
