Patent ID: 7154095

Claim:
A radiation sensitive sensor for detecting fire, said sensor comprising: a single fixed electromagnetic radiation detector sensitive to a narrow band of an electromagnetic radiation spectrum centered about a predetermined frequency of interest associated with fire; a rotatable infrared radiation directing device to receive infrared radiation from a first predefined angle in a first direction and from a second predefined angle in a second direction perpendicular to said first direction wherein said directing device is only rotatable in said second direction and wherein said directing device directs said radiation to said single fixed electromagnetic radiation detector; sector control device for sequentially rotating said directing device in said second direction in a series of increments provide stopping points at each of a plurality of sectors, each of said plurality of sectors receiving radiation from an angle in said second direction equal in value to said second predefined angle; output control device for controlling said sector control device and said radiation detector to provide a series of detected radiation output signals for each of said plurality of sectors and for controlling a duration between rotation from one of said plurality of sectors to an adjacent one of said plurality of sectors; a signal processing device for analyzing said series of detected radiation output signals output from said detector including a first short term signal analyzing device for measuring signal strength and a second longer term analyzing device for measuring signal information content after an indication of presence of fire is provided by said first short term signal analyzing device.