Abstract: A self-contained smoke detector system has internal self-diagnostic capabilities and accepts a replacement smoke intake canopy (14) without a need for recalibration. The system includes a microprocessor-based self-diagnostic circuit (200) that periodically checks sensitivity of the optical sensor electronics (24, 28) to smoke obscuration level. By setting tolerance limits on the amount of change in voltage measured in clean air, the system can provide an indication of when it has become either under-sensitive or over-sensitive to the ambient smoke obscuration level. An algorithm implemented in software stored in system memory (204) determines whether and provides an indication that for a time (such as 27 hours) the clean air voltage has strayed outside established sensitivity tolerance limits. The replaceable canopy is specially designed with multiple pegs (80) having multi-faceted surfaces (110, 112, 114).

Abstract: A process and apparatus are provided for calibrating an individual smoke detector prior to installation so its sensitivity can be determined easily throughout its useful life. Representations of detector output signals are stored in the detector prior to installation, preferably at the time of manufacture, and used later for determining the sensitivity of the detector. The signals may represent alarm and clean-ambient conditions, or one of such conditions and the difference between them. During monitoring of the detector, after its installation, a new reading of a corresponding signal under clean-ambient conditions is sampled and the differences before and after installation are compared to determine the sensitivity of the detector when it is monitored. The detector includes electrical contacts from which a representation of detector sensitivity is available for monitoring with an external electrical probe, such as a common voltmeter.

Abstract: A smoke type fire detector accurately detects a smoke density even when an internal temperature thereof changes. An internal temperature detecting unit detects an ambient temperature at a light emitting element and a light receiving element. A correction coefficient having a value associated with the ambient temperature detected by the temperature detecting unit is used to correct an output level of the light receiving element.

Abstract: A device (7) for testing the operation of smoke detectors (3) has a housing (1) which is open at one end and can be placed over the smoke detector (3). A test light source (5) in the housing provides light pulses which radiate into the inside of the smoke detector (3) under test. The test device also has a test light detector (4) that receives light coming from the smoke-indicating light source (15) of the smoke detector (3) and controls the test light source (5) in relation to the received light. The light pulse of the test light source (5) is received by the smoke-indicating light detector (14) of the smoke detector (3). By checking if the smoke detector (3) goes into the alarm state, it can be ascertained whether it is in an operational condition.

Abstract: The present invention provides a method for detecting whether an alarm circuit is operating outside its sensitivity range, the alarm circuit having a background signal and a preset alarm threshold signal. The method involves: a) multiplying the background signal by a first gain factor to produce a first test signal; b) comparing the first test signal against an alarm threshold signal; c) multiplying the background signal by a second gain factor less than the first gain factor to produce a second test signal; and d) comparing the second test signal against the alarm threshold signal. The alarm circuit is operating outside its sensitivity range when the first test signal is less than the alarm threshold signal or the second test signal is greater than the alarm threshold signal.

Abstract: A mobile fire detecting system for detecting fire conditions at the incipient stage before visible smoke has been released having an air sampling fire detector mounted to a cart supported by wheels. A tubular network in communication with the air sampling detector has a manifold enclosed by a box with four sensing hoses releaseably connected to the lateral outlets of the manifold and a telelscoping mast supporting the manifold to position it at selectable heights. Four sampling heads are connected to the other ends of the sensing hoses and are peripherally spaced equally so that the maximum area is sampled for air to detect fire conditions.

Abstract: A separate type photoelectric smoke sensor having a light emitting section for emitting a light beam to a reflecting plate disposed at a certain distance from the light emitting section, a light receiving section for receiving reflected light from the reflecting plate, and a judgement section for outputting a sense signal if a received light output from the light receiving section is smaller than a threshold value previously set.

Abstract: For testing or/and adjusting a scattered-light smoke detector as to sensitivity to smoke, a transparent body with included scattering centers is introduced into the measurement volume of the detector. Aluminum oxide powder particles can serve as scattering centers. The distribution of light scattering centers is preferably uniform, and their concentration chosen to simulate a smoke density corresponding to the alarm threshold of the smoke detector. Thus, scattered-light smoke detectors are readily calibrated to a desired output signal as a function of smoke density. With a different density of scattering centers, the technique can be used for testing scattered-light smoke detectors in the field. If the scattering centers are distributed outside a measurement volume of an uncontaminated detector, the technique can be used for testing as to contamination.

Abstract: A photoelectric sensor of the present invention includes a light emitting device and a light receiving device for detecting scattered light due to smoke, a light emitting confirming device which lights up when a quantity of light received by the light receiving device is greater than or equal to a threshold and a test light emitting device for emitting light to the light receiving device during the test, wherein a blinking of the light emitting confirming device is started at a time of a test start, and a quantity of light received by the light receiving device is increased in steps so that the blinking is stopped when the quantity is greater than or equal to the threshold. Accordingly, the sensitivity test can be performed by visually counting the number of blinkings of the light emitting device.

Abstract: A photoelectric type fire detector has: a detector body; a printed circuit board disposed on the upper side of the detector body; conductive connecting members provided on the lower side of the detector body; terminal screws for simultaneously fixing the printed circuit board and the conductive connecting members to the detector body; an optic base directly placed on the upper side of the printed circuit board and having a labyrinth formed on the upper side thereof; hooks for fixing the optic base to the upper side of the printed circuit board; a light-emitting element and a light-receiving element arranged in a pair for detecting smoke; a bug screen provided on the outer periphery of the labyrinth of the optic base; an optic base cover covering the upper side of the optic base; and a protective cover covering the printed circuit board, the optic base, the bug screen and the optic base cover.

Abstract: A light emitting device for projecting a light beam onto a monitor area, and a light receiving device, arranged so that a light beam is not directly received by the device, for receiving diffused light caused as a result of fine particles, such as dust, or smoke caused by a fire, entering the monitor area, are provided. Also, an amplifying device for amplifying an output from the light receiving device, and a counting device for counting the output from the amplifying device in units of time are provided. In addition, a computing device for computing an average value or an integrated value of the output from the amplifying device in units of time, and a determining device for determining the level of contamination of the monitor area on the basis of the count value of the counting device and for determining the level of the fire on the basis of the average value or the integrated value computed by the computing device, are provided.

Abstract: A smoke detecting apparatus for a fire alarm has: a smoke chamber into which smoke to be detected is introduced, a light emitting lamp disposed in the smoke chamber, a light receiving element disposed in the smoke chamber so as to receive the light emitted from the light emitting lamp, an A/D converting circuit for converting the output signal from the light receiving element into a digital signal, a memory for storing data therein, a computing device for storing in said memory, as first calibration data, the output data from the A/D converting circuit when the smoke chamber is filled with a first reference gas, storing in said memory, as second calibration data, the-output data from the A/D converting circuit when the smoke chamber is filled with a second reference gas, and computing a proper smoke density corresponding to the output data from the A/D converting circuit on the basis of the first and second calibration data and the output data from the A/D converter circuit, and a display device for displayin

Abstract: A photoelectric smoke detector has test circuitry for testing the detector by increasing the sensitivity thereof. The sensitivity is increased by either altering a bias condition of a photosensor or by altering a gain parameter of the detector. The detector returns to a quiescent state when the sensor returns to its original bias condition or when the gain parameter returns to its quiescent value.

Abstract: Optical smoke detectors such as extinction smoke detectors and scattered-light smoke detectors include a radiation source, a radiation detector or receiver, and a measurement volume which is in communication with ambient atmosphere and which is traversed by a light path from the radiation source to the radiation receiver. For compactness and simplicity, such an optical smoke detector is provided with a planar-optical element in the optical path. Suitable as planar-optical elements are diffractive elements, e.g., holographic-optical elements (HOE), and micro-Fresnel elements (MFE), e.g., micro-Fresnel reflectors (MFR).

Abstract: A smoke detector in which a plurality of labyrinth members are disposed on an upper wall in a standing position. In an area surrounded by the labyrinth members, a smoke detecting chamber is formed. A light emitting device and a light detecting device are disposed in such a manner that their optical axes intersect each other at the center of the smoke detecting chamber. In order for the visual field of the light detecting device with respect to the smoke detecting chamber to be restricted to the front area thereof, the labyrinth member which cross the optical axis of the light emitting device is formed so as to be longer than the other labyrinth members, and a gap is formed between the front end of the long labyrinth member and a light shielding plate for preventing the light emitted by the light emitting device from directly reaching the light detecting device.

Abstract: A silencable photoelectric-type detector includes a source of radiant energy and a detector. A generator circuit provides a sequence of pulses to energize the source. A biasing circuit biases the detector. The detector can be temporarily silenced, when in alarm, by reducing the energy level of the pulses or altering the bias point of the detector for a period of time. The period of time can be established by an RC circuit. The effect of the energy level reduction or the bias point alteration is to reduce the sensitivity level of the detector temporarily.

Abstract: An obscuration type optical smoke monitor is provided for use particularly in dusty and dirty environments. The smoke monitor comprises a housing enclosing a smoke monitoring chamber; two access ports located opposite each other on the housing; a shunt air flow path located between said two access ports; means to conduct air from said access ports through an optical chamber; a light emitting diode at the first end of said optical chamber, which light emitting diode produces a light beam axially through the center of said optical chamber; a photo transistor at the second end of said optical chamber to receive the light bean and issue an electrical signal proportional to the received light intensity; and an electronic module which provides variable electronic output, generating an analog output essentially proportional of the optical obscuration caused by the smoke.

Abstract: A integrated IR detector for detecting both motion and fire/smoke includes in one embodiment a single source of IR radiation and separate IR sensors for sensing motion and smoke. The separate sensors are coupled by their outputs to separate amplifier circuits and provide separate outputs indicating motion (intrusion) detection and smoke detection. The entire arrangement of IR source and dual sensors are mounted in a single housing and powered by a common power supply. In a second embodiment, a single passive IR motion detector having a pair of phase opposed series connected sensors is coupled to a circuit for detecting motion (intrusion) while one of the pair of sensors is coupled to a circuit for sensing changes in ambient temperature. The circuit for detecting ambient temperature changes includes logic analysis and time constant filtering to produce an alarm signal only when ambient temperature changes exceed a preset threshold rate of degrees per second.

Abstract: An improved smoke detector in combination with a fan assembly for reducing the likelihood of smoke detector activation by ambient smoke, has a fan with a timer controlling the fan's motor to automatically shut off the fan either when the time has expired or if the timer fails.

Abstract: A smoke detector includes a dark chamber surrounded by a peripheral wall structure having a plurality of nested vanes. The second element of each vane is shorter than the first, and intersects the first element intermediate its ends at an acute angle. Adjacent vanes define a tortuous path that requires a minimum of three, and in most cases four, reflections for light to reach the inside of the chamber. Adjacent vanes define twisted channels leading from outside the chamber into the chamber for blocking light without substantially restricting the flow of air. The channels each include an outer section that extends in a direction toward the center of said chamber to define a channel entrance that admits airborne smoke with approximately equal resistance from opposite directions. The channels also define second and third sections that bend inwardly from the entrance toward said chamber, first in one direction and then sharply in another direction.

Abstract: A pollution monitoring device including a fluid sampling chamber (21), a collimated light source (14, 15) directing a light beam (10, 11) into the chamber, a port (23) for introducing sample fluid into the chamber exposed to the light beam, a light detector cell (16) separated or shaded from the light beam and focussing apparatus (17) for directing scattered light produced by the presence of suspended particles and molecules in the chamber towards the detector. The source may be two lasers with co-linear beams or an LED. There is also disclosed a sample area of small diameter in which a light beam traverses the area across the flow path of a sample fluid and a projector projecting scattered light from particles into a light receiving zone of notional triangular shape having an included angle of less than 60.degree., to enable discrimination of particle size discrimination.

Abstract: In a scattered-light smoke detector, for preventing false alarms due to extraneous matter in a measurement chamber (1), a radiation source (2) and two radiation detectors (7, 8) are included. An evaluation circuit is provided for comparing the two detector signals, and an alarm signal is triggered if at least one of the detector signals exceeds a predetermined threshold, and if the two detector signals are at least approximately equal. In another embodiment, a scattered-light smoke detector includes two radiation sources (2, 22), a radiation detector (7), and circuitry for alternatively activating one (2) or the other (22) radiation source. For comparison, corresponding detector signals are stored in sample-and-hold circuits, and an alarm signal can be triggered depending on the same tests. Furthermore, in both cases, a trouble signal can be produced if the two signals are significantly different.

Abstract: A smoke detecting apparatus includes a lamp, a light receiving element for receiving light from the lamp, and a smoke detecting circuit for detecting the smoke density in accordance with the signal outputted from the light receiving element. The apparatus further includes a light emission failure detector and counter for detecting a light emission failure in which the lamp fails to emit light in response to a light emission instruction from the smoke detecting and counting light emission failures, and a memory for storing the number of light emission failures. The apparatus may further include a warning unit which, when the number of failures becomes a predetermined value or more, warns that the lamp will soon be exhausted. Thus, the unit enables a maintenance person to replace the lamp without fail before it is exhausted.

Abstract: A thin-type photoelectric smoke detector which is less susceptible to the effect of disturbance light noise, contamination of a smoke detecting unit, etc., and which ensures high sensitivity for the optical detection characteristic of the smoke detecting section. In the photoelectric smoke detector of the type in which infrared light is irradiated into a flat smoke detecting chamber and the scattered light of the irradiated infrared light due to smoke entering into the smoke detecting chamber is detected by a light-sensing element, there are provided optical members for expanding the visual field of the light-sensing element to a flat visual field corresponding to the cross-sectional shape of the smoke detecting chamber.

Abstract: A fire alarm system which radiates light towards a smoke detecting space. Scattered light resulting from smoke that may exist in the smoke detecting space is judged by a receiver with respect to the type of smoke that may prevail in the space. The presence of a fire is judged by comparing the light that has been received with a set threshold level. The threshold level is set to different levels in accordance with the type of smoke detected.

Abstract: A method for testing smoke sensor is to set a predetermined level for alarm generation on the basis of information on a first output of a main light receiving element for a stray light caused by an emitted light from a main light emitting element, a second output of an auxiliary light receiving element for the emitted light directly received from the main light emitting element and a composite output of the first and second output whereby tests for confirming normal operation and the like of the smoke detector can be executed with high precision.

Abstract: A smoke supervisory system comprising a visible image processor for calculating a differential image between a reference image and an input image and calculating parameters in the differential image; an address overlap detector for detecting whether the differential images overlap each other; an image element number change detector for detecting a change in the image element number of the differential image; and an address ratio change detector for calculating an address ratio of the differential image; or an equipment supervisory system comprising an image fetch device for fetching a reference image and an input image from an infrared image pick up device; a mask control device for masking the reference image and the input image; a differential operation device for calculating a differential image of an unmasked dividing image; a temperature distribution difference detector for detecting a maximum temperature and a mean temperature of a temperature distribution from the differential image and calculating a t

Abstract: A high sensitivity smoke detector comprises a cylindrical housing incorporating a sampling chamber through which air to be sampled is forced. A modulated light source, such as a laser, directs modulated light through the chamber to a beam dump. The light beam is offset from the axis of the housing by an acute angle of between 15 and 50 degrees. If any smoke particles are positioned within a sampling volume, the light is scattered along a path defined by baffles to an axially positioned light sensor whose electrical output is passed through a phase-sensitive detection circuit which is referenced by the frequency at which the light source is modulated, so as to produce an output dependent on the light scattered by the smoke particles.

Abstract: A fire detection apparatus discriminates white smoke, black smoke and flame in a protected area based on changing characteristics of optically measured distances. The apparatus includes a distance meter having a light emitter for emitting a pulse of light energy towards a reference object, such as a distant wall, and a light detector for receiving the pulse of light energy reflected from the reference object or any intervening object. A distance to the reference object or the intervening object is determined based on the lapse of time from the emission to the detection of the pulse of light energy. White smoke is deemed detected when the distance measured is less than a reference difference and is substantially free of fluctuations. Black smoke is detected when the distance measured is more than the reference distance and is also substantially free of fluctuations. Flame is detected when the distances measured differ from the reference distance and fluctuates substantially.

Abstract: A smoke density monitor system comprises an imaginarily dividing a space to be monitored two-dimensionally into a plurality of imaginary subspaces so that plural paths passing through a plurality of arbitrary subspaces are arranged to intersect each other; measuring the transmittance of light along each path; calculating a transmittance of light at each imaginary subspace using a mathematical method in which the measured result of the transmittance of the each path are placed into matrices and the solution to an equation involving the matrices is carried out with matrices; and determining a smoke density at each of the imaginary subspace on the basis of the transmittance at each subspaces.

Abstract: An improved smoke detector incorporating means for verifying the detector's smoke sensitivity limits, such verification means including means for positively positioning various light reflecting surfaces to provide predetermined light reflection onto light sensing means to create simulated smoke levels.

Abstract: A photoelectric smoke detector has a circuit substrate coupled to an optical-system base as disposed in a circuit accommodating zone defined within a detector housing by the base together with a smoke supervisory zone, a light projecting element and an integrated circuit incorporating therein a light receiving element and smoke detecting means are mounted to the circuit substrate, and the optical-system base holds therein a light receiving lens which is capable of condensing scattered light from smoke particles onto the light receiving element in the integrated circuit on the circuit substrate. Effective reduction in the number of constituent parts is thereby attained, to promote reduction in manufacturing costs, and to effectively realize dimensional minimization.

Abstract: A sensor in IC formation has a light emitting means, and a light receiving means disposed for receiving a faint pulsed light generated by scattering of light emitted from the light emitting means, in which a switching means capable of short-circuiting between sensor circuit lines is provided for being triggered by a counter means operated in response to an output from the light receiving means, and constituent elements of respective components of the sensor including the said means and capable of being formed in the IC are formed as integrated circuits on a dielectric isolation substrate, whereby electric isolation of the respective elements can be made complete irrespective of light irradiation to realize effective interelement junction and isolation.

Abstract: In a conventional TV, audio or other equipment having a speaker(s) and a source of power. A smoke detector is mounted inside the TV case, the output of the smoke detector being connected to the TV speaker and a power supply connected to the TV source of power, the output of said power supply being connected to the smoke detector, the smoke detector and power supply being packaged together and installed inside the case of the TV. A second oscillator may be added to thereby emit at least four frequencies because of the hetrodyning of the two oscillators.

Abstract: A light-scattering-type smoke detector is disclosed which comprises a base portion to be secured to a ceiling, a head part forming one of the parts of a detecting portion to be detachably mounted to the base portion through setscrews passed therethrough, and a dark box forming the other of the portions of the detecting part to be detachably connected to the head part by screwing the setscrews thereto, the dark box comprising a body portion and a cover portion put one upon another. The body portion has a printed circuit board integrally secured thereto on its upper surface and the dark box is surrounded by a labyrinth around its outer periphery that is internally provided with a light projection element and a light receiving element. The smoke detector allows the dismounting of the head part from the base portion, and the dark box from the head part so that maintenance and repair of the smoke detector can be carried out quite easily.

Abstract: A method for operating an optical smoke detector, wherein for smoke detecting purposes at least one light sensitive receiver within a detection chamber measures the useful scattered radiation which emanates from a volume unit within said chamber which is located in the intersecting area of the collimated field of view of said receiver and of the collimated beam of a light source within said chamber, said receiver sensing the scattered radiation caused by a contamination of said chamber or a second light sensitive receiver detecting the radiation reflected from a surface unit of said chamber, respectively, whereby measuring the reflexion radiation emanating from an illuminated surface unit within said chamber.

Abstract: An environmental detection system particularly useful for fire detection and suppression is provided which ensures high reliability in operation and high reliability in preventing false operation. The preferred system includes a microprocessor-based, software-governed, control panel connected to one or more detector loops. Each loop includes a plurality of parallel-coupled, addressable detectors which send analog signals to the control panel representative of an environmental parameter such as smoke obscuration along with reference and identification signals. The preferred system provides automatic calibration and test of the detectors, automatic testing under load of the backup batteries, flexibility in defining the protective scheme, and storage of history information concerning system alarms and troubles. The preferred system also verifies alarm conditions before actuating an alarm or discharging a fire suppressant.

Abstract: An alarm system for warning of a creosote chimney fire hazard, having both means to produce a visible alarm when the creosote temperature is nearing the creosote flash point, and means to produce an audible alarm when light from actual ignition of a creosote fire is detected. The invention also provides means to discriminate against detection of wood fire light, to minimize false alarms.

Abstract: A focused beam of light from a light source is directed into a closed smoke chamber, having inlets for admitting smoke particles, toward a reflector which reflects and refocuses the beam back into the light source, the direct beam and the reflected beam passing through a test zone within the chamber. In the event that smoke particles enter the test zone, the direct and reflected beams strike and bounce off of those particles to produce scattered radiation that will be picked up and detected by a light responsive sensor to generate an alarm signal. By closely controlling, rather than baffling the light, optimum operation is obtained, efficiency is enhanced and false alarms are minimized.

Abstract: A system for testing a remotely located sensing unit includes a photosensor located within the sensing unit. A control beam of incident electromagnetic energy can be provided from a remotely located portable source such as a flashlight. Directing the beam of radiant energy from the flashlight against the sensor in the unit causes the unit to initiate a test sequence. The unit can be equipped with a photo-detector to terminate an alarm generated in response to a sensed condition. The unit can include a sonic detector. Control circuitry in the unit can decode a sensed encoded incident beam to minimize false tests or to provide multiple remotely initiated functions.

Abstract: A scattered-light smoke detector having an improved shield structure. A detector circuit is provided on a printed circuit board which is disposed at an upper portion of a smoke detecting section. The smoke detecting section includes a planar base and a surrounding wall extending downwardly from a lower surface of the base and having an opening or openings which allows or allow smoke to enter therethrough. The surrounding wall defines a smoke detecting space therein. A light emitting element and a photodetector element which are disposed at positions where they are not opposite each other and optical axes thereof intersect each other at a predetermined angle and said photodetector element can receive light from the light emitting element scattered by smoke entering the smoke detecting space. The printed circuit board is attached on an upper surface of the base. A shield layer is interposed between said printed circuit board and said base.

Abstract: A station for locating through laser rays an object likely to diffuse back a part of the incident laser ray, wherein the optical emitter and receiver devices consist of one single device comprising, in the direction of emission, a device for separating the emitted and retrodiffused rays, an optical device converting the emitted parallel beam of small diameter into a divergent beam and a telescope adapted to collimate the divergent beam received from the optical device into a parallel beam of larger diameter, the retrodiffused beam travelling that path in the direction reverse from the emitted beam, the invention being usable for detecting in particular forest fire smokes.

Abstract: A light scatter smoke detector includes an infrared light source and light sensor in a smoke chamber, the chamber including an adjustable screw which serves as a scatter reflector to provide an operating voltage used both in normal operation and for testing. A dual channel is also provided by a splitting off some light from the light source into a separate reference channel which is also used for threshold detection or proper ratioing.

Abstract: A detector for sensing or measuring objects passing a measurement path (5) has a detection element (6), the output signal of which is a function of objects discovered in the measurement path. The output signal is fed to an amplifier and filter circuit (7-9), the output of which is connected to two parallel integration cirucits (11, 12). The integration circuits have time constant (.tau..sub.SH, .tau..sub.L) of different magnitudes, and their output signals are fed to a comparator (13) for obtaining an operative signal indicating the presence of an object in the measurement path, this signal being unresponsive to long-duration fluctuations in the detector's operating conditions, e.g., dirtying of the detection element. The detector includes a dirtiness alarm with the threshold response adjustable to a long-time-constant integrator output.

Abstract: In a combined obscuration and scattered-light smoke detector, light from a light source in a smoke chamber is reflected from an image-forming optical component onto a first light sensor which senses a reduced electrical signal in the presence of smoke while a second sensor, viewing light from the light source at an angle, senses an increased electrical signal in the presence of smoke. The output of each receptor is subjected to a band pass filter, an amplifier and a comparator; the resultant signals insure early and reliable activation of an alarm when even a low level of smoke is present in the smoke detector. A second light source having a wavelength different from that of the first light source provides, in the obscuration mode, added sensitivity to smoke.

Abstract: A photoelectric smoke detector of this invention comprises a smoke-detection arrangement including a light emitting element and a photodetecting element and a smoke-detecting unit on which said smoke-detection arrangement is mounted. The smoke-detecting unit includes a base plate to which said smoke-detection arrangement is attached and a peripheral wall having such a configuration that allows smoke to enter from the outside, but substantially prevents light to enter from the outside. The peripheral wall is formed of a plurality of wall elements, each of said wall elements is arranged substantially regularly and formed integrally with said base plate so as to extend downward from the base plate. The smoke-detecting unit further includes an insect net which has been fixed to the outer surfaces of the wall elements in the shaping process of the smoke-detecting unit so as to be fit around the outer periphery of the peripheral wall.

Abstract: A sensor system for the detection and/or analysis of smoke, gas or the like, comprising a detection means 6 connected to an analyser means 2 via fiber-optic links 3, 11 and 12. The detector 6 determines the presence of smoke, gas or the like, while the analyzer 2 analyzes the composition of the smoke, gas or the like. The exact location and nature of the smoke, gas or fire can therefore be determined with the aid of suitable associated circuitry 9.

Abstract: A system for testing a remotely located sensing unit includes a photosensor located within the sensing unit. A control beam of incident electromagnetic energy can be provided from a remotely located portable source such as a flashlight. Directing the beam of radiant energy from the flashlight against the sensor in the unit causes the unit to initiate a test sequence. The unit can be equipped with a photo-detector to terminate an alarm generated in response to a sensed condition. The unit can include a sonic detector. Control circuitry in the unit can decode a sensed encoded incident beam to minimize false tests or to provide multiple remotely initiated functions.

Abstract: A modular transceiver head including cooperative cover and base members operable as a transmitter or as a receiver of infrared energy. The cover member includes a window defining a comparatively wide field of view in azimuth and in elevation. An optical train including a gimbaled specular member that is mounted to the base member readily allows both rough and fine adjustment of the pointing direction of the specular member anywhere within the field of view of the cover member window. A controller including a processor is coupled to a transceiver head pair respectively operative as a transmitter and as a receiver of infrared energy to controllably project a beam of infrared energy therebetween through a protected region. The controller is operative to de-sensitize the beam against potential electrically interferring effects present along the beam path. The controller is periodically operative in a self-test mode to reduce the intensity of the projected-beam to simulate a smoke condition.

Abstract: In a smoke detection system, smoke density in a sampling chamber is measured by flashing a strobe light through the chamber and sensing light flux emitted from the chamber and comparing it with light flux from the strobe light itself. The measurements are performed by peak detectors which load sample-and-hold circuits to provide steady signals. The two signals are combined in mathematical manner to compensate for zero-offset and rate error between the two signals. The combined and corrected output is used to actuate a visual alarm signal, such as a segmented bargraph display to indicate air pollution. The bargraph has programming pins for tapping off each individual bargraph segment to achieve plural preset alarm thresholds.