IONIZATION TYPE SMOKE DETECTORS WITH FET PROTECTED AGAINST OPEN CIRCUIT INPUT

摘要

In an ionization type smoke detector wherein smoke is introduced in an ionization chamber through a mesh electrode and the change in the ionization current caused by the smoke is detected by the potential difference between the gate and source electrodes of a field effect transistor, means is provided to short circuit the gate and source electrodes in response to the removal of the mesh electrode.