| 摘要 |
A detector suitable, for use as a fire detector, comprises a first sensor (16) to detect radiation at two different wavebands, at or about 3.8Ám and 4.8Ám and at least a second sensor (14) to detect radiation at a third waveband, at or about 4.3Ám, means to calculate an expected value of radiation for the second sensor by interpolating between the signals from the first sensor, and then compare the expected value with the actual result such that if a preset threshold value is exceeded an alarm is triggered. A notch filter (18) is used in combination with a sapphire filter (12) to ensure that the radiation at or around 4.3Ám is detected by the second sensor and not the first. The detector is able to discriminate between energy received from a fire and a "false fire" as a result of "cold" black body radiation signals at flame flicker frequencies.
|
