| 摘要 |
<p>A fire detector having an ionization sensing means which changes the level of an output signal in accordance with sensing the presence of smoke in the atmosphere has been provided. A detecting means selectively responsive to the output signal generates an alarm control signal and the improvement includes a filter means for rendering a detecting means operable if uninhibited to generate the alarm signal irrespective of an output signal from the sensing means. Inhibiting means normally operable to inhibit the filter is rendered ineffective in response to the output signal of the sensing means and the inhibiting means therefore checks the operability of the detecting means.</p> |
