Birch, Stewart, Kolasch & Birch
Ionization type smoke sensing device
 An ionization type smoke sensing device includes a printed board. An inner electrode made of heat-resistant metal is attached to the printed board and a radioactive source is fixed to the inner electrode. An outer electrode in the form of a bottomed cylinder made of heat-resistant metal and adapted to cover the inner electrode extends through the printed board and is integrally joined to a protective lid member made of heat-resistant metal at the back of the printed board. Therefore, the outer electrode and the lid member cooperate with each other to define an ionization chamber. The outer electrode is formed with smoke inlet ports for introducing smoke into the ionization chamber. The electric circuit serves to give pulse signals of a relatively high voltage to the outer electrode and to detect the presence of smoke on the basis of the amount of a current flowing through the inner electrode. 
Matsushita Electric Works, Ltd.
G G H
G08B G08B H01J
inventional inventional inventional
Yoshihiko Takeshi Tsunehiko
Okuda Nakano Araki