| 摘要 |
In an ionising smoke detector which is designed as an air capacitor, the space between the capacitor faces is subdivided into a large, variously ionised space and a small space ionised as far as saturation by a weak alpha radiator. The dielectric constant of this capacitor varies with the composition of the air in the large space. The capacitor plates are exposed to the free air, and one of them bears the radiation source. Arranged near this source is a collector electrode which is connected to an electronic differentiating circuit which triggers the alarm signal. The detector can be used for the purposes of detecting fires or air pollution. <IMAGE>
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