US 4,052,716 A · Fire and intruder detection and alarm apparatus

Abstract

Improved apparatus is provided for monitoring a space under surveillance, for detecting the existence of a fire, the presence of an intruder or the occurrence of other abnormal conditions, and for providing a warning signal for actuating an alarm or the like in response thereto. The apparatus employs a plurality of sensors which respond by changes in the electrical characteristics thereof to the level of infrared, light or other radiations from the monitored space respectively sensed thereby. The apparatus significantly provides means for rendering the individual sensors directionally responsive to radiations from respectively corresponding portions of the space being monitored, for employing such sensors as output-affecting elements in more than a single arm of an electrical bridge circuit, for employing such sensors when desired in a plurality of operationally related electrical bridge circuits, for employing capacitative coupling between the output of a sensor-controlled bridge circuit and a differential amplifier to "mask" very slow changes in the output of the bridge circuit due to normal ambient variations while retaining high sensitivity in responding to more rapid changes of such output typical of fire, intruder or other abnormal conditions requiring alarm actuation, for employing such differential amplifier for converting changes in capacitatively coupled output from a sensor-controlled bridge circuit into direct current signals of polarity dependent upon the direction of change in such bridge circuit output, and for employing bridge type rectification for converting signals of either polarity from such differential amplifier into control signals of a single polarity for actuating an alarm activating switching component.

Claims16

Dependent claims

For use in alarm systems or the like wherein at least a pair of adjacent portions of a single space are under surveillance, apparatus for detecting changes in the nature of free-space radiations emanating from said adjacent portions resulting from an occurrence associated with an alarm condition including:

at least one pair of radiation responsive sensing means each having a pair of electrical connection points and characterized by presenting between said points an electrical parameter of variable level which changes in response to changes in the level of radiations being sensed,
said one pair of said sensing means being operative to sense radiations emanating from said adjacent portions of said space;
means for rendering each of said one pair of said sensing means respectively operative to receive and sense radiations emanating from corresponding ones of said adjacent portions of said space;
electrical bridge circuit means having a pair of opposed reference terminals, a pair of opposed output terminals, and a plurality of electrically conductive bridge arms respectively extending to each of said output terminals respectively;
means electrically coupling said points of each of said one pair of said sensing means respectively in electrical series with the respective ones of one adjacent pair of said bridge arms;
and
means for detecting changes occurring in an electrical parameter presented between said output terminals in excess of a prescribed rate of change of said parameter and indicative of an alarm condition, whereby changes including those due either to a fire or to the presence of an intruder in either of said adjacent portions of said space will be detected, while slow changes due to gradual alteration of radiation conditions such as the ambient temperature of said adjacent portions will be ignored.

4 more elements

For use in alarm systems or the like wherein at least one portion of a single space is under surveilance, apparatus for detecting changes in the nature of freespace radiations emanating from said portion resulting from an occurrence associated with an alarm condition including:

a first plurality of radiation responsive sensing means each having a pair of electrical connection points and characterized by presenting between said points an electrical parameter of variable level which changes in response to changes in the level of radiations being sensed,
at least one of the sensing means included in said first plurality thereof being operative to sense radiations emanating from said one portion of said space;
means for rendering each of the remaining of said first plurality of sensing means respectively operative to receive and sense radiations emanating from some corresponding portion of said space;
a second plurality of radiation responsive sensing means each having a pair of electrical connection points and characterized by presenting between said points an electrical parameter of variable level which changes in response to changes in the level of radiations being sensed,
at least one of the sensing means included in said second plurality thereof being operative to sense radiations emanating from said one portion of said space;
means for rendering each of the remaining of said second plurality of sensing means respectively operative to receive and sense radiations emanating from some corresponding portion of said space;
first electrical bridge circuit means having a pair of opposed reference terminals, a pair of opposed output terminals, and a plurality of electrically conductive bridge arms respectively extending from each of said reference terminals respectively to each of said output terminals respectively;
means electrically coupling said points of each of said first plurality of sensing means respectively in electrical series with a different one of said bridge arms of said first bridge circuit means;
second electrical bridge circuit means having a pair of opposed reference terminals, a pair of opposed output terminals, and a plurality of electrically conductive bridge arms respectively extending from each of said reference terminals respectively to each of said output terminals respectively;
means electrically coupling said points of each of said second plurality of sensing means respectively in electrical series with a different one of said bridge arms of said second bridge circuit means;
detecting and control means electrically coupled with said output terminals of said first and second control bridge circuit means for activating an alarm or the like in response to changes occurring in an electrical parameter presented between said output terminals of either of said first and second bridge circuit means.

8 more elements

For use in alarm systems or the like wherein at least one portion of a single space is under surveillance, apparatus for detecting changes in the nature of free-space radiations emanating from said portion resulting from an occurrence associated with an alarm condition including:

at least one pair of radiation responsive sensing means each having a pair of electrical connection points and characterized by presenting between said points an electrical parameter of variable level which changes in response to changes in the level of radiations being sensed,
each of said sensing means being respectively operative to sense radiations emanating from substantially overlapping areas in said one portion of said space;
electrical bridge circuit means having a pair of opposed reference terminals, a pair of opposed output terminals, and a plurality of electrically conductive bridge arms respectively extending from each of said reference terminals respectively to each of said output terminals respectively;
means electrically coupling said points of each of said one pair of said sensing means respectively in electrical series with the respective ones of one opposing pair of said bridge arms;
and
means for detecting changes occurring in an electrical parameter presented between output terminals.

3 more elements

Dependencies are inferred from the claim text.

Fire and intruder detection and alarm apparatus

Life of this patent

Fire and intruder detection and alarm apparatus

Life of this patent

Abstract

Claims16