US 4,306,230 A · Self-checking photoelectric smoke detector

Abstract

A photoelectric smoke detector for providing indications of both alarm and trouble conditions is disclosed having a source of light, a detector apparatus having a light responsive device, said detector apparatus providing an output subject to a first change dependent upon the presence of smoke, the smoke detector further having a housing for mounting the source of light and the light responsive device, the housing having light path means for allowing light from the source of light to fall upon the light responsive device, the output from the detector apparatus being subject to a second change dependent upon trouble conditions, a first level sensor responsive to the first change to provide an alarm indication, and a second level sensor responsive to the second change to provide a trouble indication.

Claims12

Dependent claims

A photoelectric smoke detector for providing indications of both alarm and trouble conditions comprising:

a source of light;
detector means having a light responsive device, said detector means providing an output subject to a first change dependent upon said alarm conditions;
a housing for mounting said source of light and said light responsive device, said housing comprising substantially direct and straight through light path means for passing light from said source of light to said light responsive device in a substantially direct and straight through light path, said output being subject to a second change dependent upon said trouble conditions;
first level sensing means responsive to said first change to provide an alarm indication;
and,
second level sensing means responsive to said second change to provide a trouble indication.

3 more elements

A photoelectric smoke detector for providing indications of both alarm and trouble conditions comprising:

a source of light;
detector means having a light responsive device;
a housing for mounting said source of light and said light responsive device, said housing comprising substantially direct and straight through light path means for passing light from said source of light to said light responsive device in a substantially direct and straight through light path to establish a predetermined output from said detector means;
first level sensing means connected to said detector means and responsive to a change in said output from said detector means in a first direction to provide an alarm indication;
and,
second level sensing menas connected to said detector means and responsive to a change in the output from said detector means in a second direction to provide a trouble indication.

3 more elements

Dependencies are inferred from the claim text.

Self-checking photoelectric smoke detector

Life of this patent

Self-checking photoelectric smoke detector

Life of this patent

Abstract

Claims12