| 摘要 |
A heat sensor for a fire detector includes a substantially hermetically sealed housing 1 defining a cavity 2 which accommodates a printed circuit board 3. A hole 5 is formed in one wall 4 of the housing and a heat sensitive electronic element 6, such as a thermistor, is supported on the printed circuit board by means of an electrical lead 7 which passes through the hole in such a manner that the heat sensitive element is disposed externally of the wall 4. An elongate projection 10 extends outwardly from the wall 4 and is sealed to the wall (4) around the edge of the hole 5. The heat sensitive element (6) is contained within the projection (10). The projection may be moulded integrally with the wall and may have different heat conducting properties to the wall. It may comprise an external pin or a metal coating in the neighbourhood of the heat sensitive element or may contain a heat conductive filler which embeds the component. <IMAGE> |
