公开(公告)号：CA1143871A

公开(公告)日：1983-03-29

申请号：CA325291

申请日：1979-04-11

Applicant: CHLORIDE GROUP LTD

Inventor： JOHNSON DENNIS ,  LETTS JOHN B

IPC: G08B17/113 ,  H01J41/08 ,  H01J47/02 ,  G08B17/10

Abstract: A smoke detector having an ionisation chamber with a central electrode which is covered by an insulator except at a restricted area closely spaced from a measuring electrode. A second electrode consisting of a perforated wall of the ionisation chamber. A conducting sleeve which is electrically connected to the second electrode surrounds the insulator on the first electrode, to minimize the effect of condensation of water on the first electrode.