| 摘要 |
<p>An ionization type smoke sensor includes an insulating base (1) which supports an internal electrode (4), and intermediate electrode (6) and an external electrode (7). The internal electrode (4) and the intermediate electrode (6) in combination constitute an inner ion chamber (8), while the intermediate electrode (6) and the external electrode (7) in combination constitute an outer ion chamber (9). The sensor further includes a radioactive radiation source (2) which irradiates both the ion chambers with radioactive rays. The insulating base (1) is formed with a vertical communication bore (1') having a diameter larger than the outside diameter of a screw (3) which is received through the bore (1'). Through the screw (3) received through the communication bore (1'), the internal electrode (4) is supported by a circuit board (10) disposed in the inner upper portion of the insulating base (1). The external electrode (7) is supported at the outer upper portion of the insulating base (1) through an interposition (11'). By virtue of such arrangement, the creeping distance between the electrodes is increased and, therefore, the insulation resistance between the electrodes is raised.</p> |
