| 摘要 |
<p>A pair of temperature detection devices (18, 19) having different heat time constants and an active device (20) having a predetermined bias are connected to one another in series. The bias is set so as to cause the active device (20) to act in a saturated region if the temperature is higher than a dangerous level and to act in a triode region if the temperature is lower than the dangerous level. Furthermore, the temperature detection devices are set so as to cause the voltage generated at the connection contact of the temperature detection devices to be made higher than a predetermined reference voltage if the temperature has been raised to the dangerous level in a case where the temperature is raised slowly or if the temperature is raised rapidly, even if the temperature is lower than the dangerous level. Thus, a constant temperature function and a differential function are realized to detect that a fire has occurred. In an alternative arrangement, Fig 7 (not shown), the series connection of one of the temperature detection devices and the active device is connected in parallel with the series connection of the other temperature detection device and a resistor. <IMAGE></p> |
