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: 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 projected region. The controller is operative to de-sensitize the beam against potential electrically interferring effects present along the beam path. Plural alarm thresholds are operator selectable to provide enhanced confidence detection, and particularized signal indications are provided to readily and quickly identify possible alarm and trouble conditions.

Abstract: An apparatus for indicating an emergency exit in case of fire in a building, includes a smoke alarm apparatus adapted to relay an electrical activating signal causing a luminous exit indicating flag to be projected outwardly from a wall adjacent an emergency exit and near the floor, for indicating exit locations to persons evacuating a smoke filled building.

Abstract: A detecting system and a detector which includes an analog sensor for sensing a change in a quantity of an environmental phenomenon, processes a signal corresponding to a detection level output from said analog sensor to detect a change in the environmental phenomenon, in which the detecting sensitivity of analog sensor may be changed between a plurality of sensitivity levels according to the quantity of the phenomenon.

Abstract: Two photoelectric smoke detectors are arranged so that each smoke detector in turn verifies operation of the other smoke detector. Each smoke detector has a light source and a photodetector which is not directly illuminated by the light source. A smoke detection signal is issued when light from such a light source is scattered to the respective photodetector. The two smoke detectors are arranged so that a small amount of light from each light source illuminates the photodetector of the other smoke detector. A fault signal is issued when such a photodetector is not illuminated by the other light source.

Abstract: A separation type light blocking smoke detector detects smoke present between a light emitting section and a light receiving section spaced therefrom by detecting blocking of light between the light emitting section and the light receiving section. The detector includes a light emitting section driving circuit, a counting circuit, and a storage circuit. The light emitting section driving circuit changes the emission intensity of the light emitting section in accordance with a predetermined changing mode for every repetitive cycle. The counting circuit includes a first comparator and an updating signal generator, and counts a physical amount corresponding to a period during which an output from the light emitting section falls in a predetermined range for each repetitive changing cycle. The storage circuit includes a second comparator and an AND gate, and stores a count value of the counting circuit in an arbitrary repetitive cycle.

Abstract: A photoelectric smoke detector is equipped with a light emitter for radiating light into a measuring space. A light receiver detects scattered light caused by the presence of smoke in the measuring space. The measuring chamber is constructed as a light trap such that the light beam radiated by the light emitter is multiply reflected and cannot reach the light receiving element of the light receiver.

Abstract: A modular transceiver head including cooperative cover and base members operable as a transmitter or as a receiver of infrared energy. 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 periodically operative in a self-test mode to reduce the intensity of the projected-beam to simulate a smoke condition. Plural alarm thresholds are operator selectable to provide enhanced confidence detection, and particularized signal indications are provided to readily and quickly identify possible alarm and trouble conditions.

Abstract: Light-scatter smoke detector, depending from the ceiling of a room, has a base unit with a battery to power an infra-red light source and infra-red light sensor, both of which are located in an upper element. A lower element has a surface corresponding to the exterior of a cone, and forming the base of a chamber. A surface makes, with a frusto-conical surface of the upper element, an annular wedge-shaped recess to chamber, this recess facing both source and sensor. The surfaces have a matt-black coating to promote energy absorption, so that the recess inhibits any light entering it from ever re-emerging. The stream of air flowing through the detector is monitored in the central chamber for the presence of smoke particles, by the sensor watching for light which originated from the source being scattered by smoke particles in the chamber and arriving at the sensor.

Abstract: A fire detector having a body comprising a cover part and a hood part and containing therein fire detecting means and electrical circuits, and a base detachably fastening the body by engaging means provided on them, respectively, is disclosed wherein in order to prevent the cover part from coming off the hood part due to shock, vibration, etc. possibly subjected thereto at the time of maintenance, inspection, etc.

Abstract: In a light-transmission type smoke detector, a smoke chamber is composed of a disc-like block of a non-conductive material one side of which has a spiral groove and is coated with a conductive bright metal film and a casing mounted on the block, said casing having a plurality of labyrinth structure smoke entrances. An electric circuit system is placed on the other side of the disc-like block and is covered by a shield sheet. The shield sheet and the coating metal film are electrically connected to shield the electric circuit system.

Abstract: A light emitting unit and a photo sensing unit are separately arranged to face with each other, and a pulse light is emitted from the light emitting unit at every constant period, and the photo sensing unit receives the pulse light attenuated by a smoke, thereby detecting a fire. When a power source is turned on, a microcomputer in the photo sensing unit stores the first photo sensing data as an initial photo sensing data in a memory. The initial photo sensing data is fixedly stored and held and is not erased due to a temporary cut off of the power source. The photo sensing data is converted to correction photo sensing data using a correction ratio to perform the fouling correction and the fire is discriminated on the basis of the correction photo sensing data. The correction ratio is corrected when the correction period reaches 50 minutes. A correction amount of a single correction ratio is suppressed to a microvalue.

Abstract: An improved fire alarm system utilizes receiver and fire detecting terminals connected thereto through a signal transmission line comprising two wires. The fire detecting terminal operates on two mode, one being a contact-closure mode of transmitting to the receiver a level signal whether or not a significantly higher fire-indicative quantity is detected, and the other being intelligent mode of transmitting a digital signal indicative of the sensed quantity in the form of a superimposed signal upon the level signal in answer to the instruction from the receiver for precise and convenient analysis thereof in determining fire presence on the side of the receiver. The fire detecting terminal includes a comparator having its own threshold with which the value of the sensed analog quantity is compared for providing the level-shifted signal when the sensed analog quantity has a level higher than the threshold, notifying fire presence independently of the intelligent mode.

Abstract: An improved photoelectric smoke detector and alarm system which may be incorporated in a single station, completely self-contained unitary structure, or which may be incorporated in a multi-station detector system that is capable of self-contained operation but which can also be interconnected with other detectors whereby when any one detector's alarm sounds, all of the other alarms automatically sound in the other interconnected structures, the improved smoke detector and alarm system including a piezoceramic electrically activatable alarm, an illuminating circuit including a gallium aluminum arsenide light emitting diode, and a smoke sensing circuit including a pair of identical photoelectric cells formed on the same substrate with the photoelectric cells mounted in proximity to the light emitting diode whereby light emanating from the light emitting diode impinges upon one of the dual photoelectric cells at all times and impinges upon the other of the dual photoelectric cells to change the conductivity of

Abstract: A light-attenuation type fire detector assembly of the present invention comprises a light emission drive section including a light emitter for radiating light having an intensity corresponding to an input signal level; a smoke detecting section including a light receiver which directly receives the light radiated from the light emission drive section and is adapted to output a detection signal corresponding to the received light amount of the light receiver; a smoke amount computing section for computing the amount of smoke based on the detection signal from the smoke detecting section; a delay circuit for retarding input of the detection signal from the smoke detecting section to the light emission drive section for a predetermined time; and a control section for repeating the operations of the light emission drive section, the smoke detecting section and the delay circuit and generating a control signal after a predetermined period of time has been passed or a predetermined times of operation has been done

Abstract: A photoelectric smoke detector which operates on the scattered light principle and involves a light source, and a photosensor placed at an angle to the light beam such that it is normally not illuminated, the light source and photosensor being located within a dark detection chamber having air entry ports that restrict ambient light; smoke particles entering the smoke chamber produce interruption of the light beam, thereby scattering light onto the photosensor. The detection chamber is formed within a cup-shaped grill which can be readily removed from the housing by rotation of the grill to disengage a locking mechanism; the grill is provided with an end wall and, integrally formed therewith, spaced inner and outer cylindrical side walls, the inner side wall being defined by baffles which include scoop fins that are used to trap light, but which also function to scoop air into the chamber and cause air turbulence for mixing the smoke particles thoroughly; the outer side wall having windows for entry of smoke.

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.

Abstract: A photoelectric smoke detector operating on a scattered light principle. The photosensor is connected at the input of an operational amplifier, such amplifier functioning as a threshold detector, saturation pulse amplifier and fixed pulse width compensator. Another feature of the invention resides in the provision of a special RC network connected from the output of a first transistor of a flasher section or subcircuit, which provides pulse power to the light source, to the input of a second transistor in such flasher circuit. As a consequence of this arrangement, when the LED serving as the light source tends to age, with a corresponding increase in its impedance, an appropriate signal is fed back from the aforenoted output of the first transistor to the input of the second, thereby to increase the pulse width of the output signal through the LED such that it is no longer, thereby compensating for the fact that it is no longer as bright.

Abstract: A smoke detector comprising a light emitting section from which pulse light is radiated to a detection area with a predetermined period and a light receiving section which is disposed so as to be opposite to the light emitting section to receive the light for detecting a change caused in the detection area in the form of a change in photo-output level. The light receiving section has a monitor terminal for outputting a monitor signal corresponding to the photo-output level. When a measuring apparatus is externally connected to the monitor terminal, the supervision period is shortened as compared with the normal supervision period, so as to enable the monitor signal to be supervised substantially in real time, thereby facilitating an adjusting operation.

Abstract: In a smoke sensing apparatus, a light receiving circuit including a light receiving element senses light emitted from a light emitting circuit including a light emitting element and scattered by smoke, and a voltage holding circuit converts the output signal of the light receiving circuit into a d.c. voltage and holds the d.c. voltage. A mean value circuit averages the voltage signal from the voltage holding circuit, and a switching circuit acts to bring the output of the mean value circuit to a level close to that of the output of the voltage holding circuit. A comparison circuit compares the output of the means value circuit with the output of the voltage holding circuit thereby generating a control signal.

Abstract: A photoelectric smoke detector is provided with first and second radiation emitters and first and second radiation receivers. The first emitter emits pulsed radiation at a predetermined frequency. The second emitter emits pulsed radiation at twice this frequency. The first receiver receives the radiation of the second emitter directly and that of the first emitter by scattering only. When the first receiver receives alternate detection pulses reinforced by scattered radiation, an alarm is generated. The second receiver receives radiation directly from the first emitter and modulates the radiation output level of the second emitter proportionately. When the first receiver receives testing pulses between the alternating detection pulses, their level is discriminated to determine the functional state of the detecting elements and a corresponding function signal is generated.

Abstract: In the light-scattering type smoke detector with a disorder detecting circuit, the Munsell value of lightness of the inside surface of the dark chamber is raised to 2-4. Thereby, not only disorder of the apparatus but also performance drop of apparatus parts can be detected.

Abstract: An environmental abnormality detecting apparatus for detecting abnormality in atmosphere such as heat, smoke, and a gas. A sampling circuit is provided for periodically sampling analog signals from a detector for detecting these phenomena. A quantizer quantizes sampled signals with step levels. An accumulator having a plurality of counters provides different accumulation times corresponding to the step levels. Reliability in accumulation effect is not degraded, and an abnormality signal can be detected in a short period of time when a degree of abnormality is high.

Abstract: A photoelectric smoke sensor terminal has an address signal detector for detecting whether or not an address assigned to the terminal coincides with an address represented by an address signal from a main unit. Only when the coincidence signal is supplied to a switch circuit is a photoelectric smoke sensor turned on. The terminal also has an item data memory for supplying item data (e.g. gas leakage and smoke generation data) so that a plurality of item data signals together with an output signal from the sensor can be transmitted on a single transmission line.

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.