| 摘要 |
<p>A thermal sensor (1,10,20,30,S) comprises first (3,13,23,33) and second (4,14,14a,14b,24,34,37,39) conductors separated by a ceramics material (6,16,26,36,A,B) which is responsive to heat whereby the resistance of the ceramics material undergoes a step change from a first resistance value (ROFF), which is the electrical equivalent of an open circuit, at a first temperature range (TOFF), consistent with the absence of a flame or applied heat or an acceptable operating level of applied heat, to a second resistance value (RON), which is the electrical equivalent of a short or closed circuit, at a second temperature range consistent (TON) with the presence of a flame or a maximum or near maximum required output of a heating surface or heating element (61). The sensor is mounted on or embedded in a heating surface to be monitored and the sensor conductors are connected to a control device for controlling the temperature of the heating surface. In an alternative arrangement, the sensor (S) is used as a flame failure device. A method for manufacturing a thermal sensor is disclosed in which the profile of the gap between the first and second conductors is determined by screen printing templates or otherwise laying conductor tracks which are etched or laser trimmed as appropriate and overlaying at least the gap with the ceramics material. Control devices (50) of the type including an energising circuit, in which the device includes a thermal sensor connected in various configurations with the energising circuit or the load to be controlled are disclosed, as are interface circuits and energising circuits for connecting the sensor to various control devices and instrumentation. <IMAGE></p> |
