| 摘要 |
An improved fire detector has both ionization chamber and photoelectric type products of combustion sensing devices, both of which must detect combustion for an alarm to be generated. The sensing devices are each adjusted to a quiescent sensitivity, but upon combustion being detected by one of the devices the sensitivity of the other device is automatically increased. In this manner, the detector operates very reliably to generate an alarm in the very early stages of a fire irrespective of whether the combustion process generates primarily visible or generally invisible type products of combustion, yet spurious generation of false alarm is minimized.
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