Abstract: In the monitoring system which is intended for buildings, rooms and objects a multitude of measuring or detecting and signaling stations are series connected to a central signal station. Each of the detecting and signalling stations transmits information about its instantaneous state, which may be any one of standby, warning, alarm, malfunction, to the central signal station by means of an electronic circuit member.

Abstract: In the apparatus for signalling an alarm, for example, in a gas or fire detecting installation, a detector is reset after a first response and the time duration until the next-following detector response is determined and classified with respect to three classes of time periods. When the time duration until the further detector response is beyond a predetermined upper or outer time limit, no alarm signal is released and the apparatus returns into its original state. When the further detector response occurs between two time limits, the alarm is immediately signalled. When the further detector response occurs prior to a lower one of the two time limits, there is carried out still one further test during which the detector is once again reset. The alarm signal will only be released if an additional further detector response is still observed prior to the upper time limit.

Abstract: A sensor element responding to gases and/or vapors is heated in at least two temperature cycles continuously from a starting temperature value to an upper temperature value in accordance with a predetermined pattern which is optimized for selective gases. The temperature is lowered to the starting temperature value in accordance with the same or a different pattern. During the temperature cycles a signal which depends on the composition of the gas or vapor atmosphere delivered by the sensor element is compared in an electronic evaluation circuit to stored values which are characteristic for the presence of selective components in the gas and/or vapor.

Abstract: In a line extinction detector using a pulse-operated radiation source, a radiation receiver is connected to an input amplifier of an evaluation circuit. The output pulses generated by the input amplifier are compared to a reference voltage. Circuit elements having a time constant above one minute are provided to adjust either one of the voltage of the output pulses or the reference voltage such that their difference practically becomes zero. The output pulses of the input amplifier are further compared to an alarm threshold derived from the reference voltage and an alarm is triggered when the output signal falls below the alarm threshold value. The output pulses of the input amplifier are also compared to a disturbance threshold value and a disturbance signal is generated when the output signal drops below the disturbance threshold value.

Abstract: A smoke detector is disclosed having a radiation source operated in a pulsed mode. Externally of a direct radiation region of the radiation source there is arranged a radiation receiver which, in the presence of smoke or other particles emanating from a combustion process and located in the radiation region, is impinged by scattered radiation and delivers an output signal to an evaluation circuit. The evaluation circuit contains switching elements which, when the number of source output signals or pulses exceeds a predetermined threshold value for the number of source output pulses, delivers an alarm signal. Near to the radiation receiver there is arranged a reference cell in the direct radiation beam of the radiation source, this reference cell controlling the emission of radiation by the radiation source.

Abstract: In an alarm system a central signal station periodically transmits interrogation signals, preferably in the form of infrared radiation packets to remotely located detectors which transmit a response signal back to the central signal station after differing time delays that are characteristic for the individual detectors and which permit the localization of the source of the response signal. In an alarm state, the detectors respond to every interrogation signal, in the normal operational state to only every m.sup.th interrogation signal, i.e. less often, and in a state of diminishing battery potential to only every small p.sup.th interrogation signal, i.e. even less often. The state of the individual detectors is determined from the frequency with which the response signals are transmitted back by the detectors, that is the ratio of the response signals to the interrogation signals.

Abstract: A smoke detector contains two radiation transmitters and two radiation receivers. Each of the radiation transmitters emits in a different spectral region, for instance, one emits above and the other one below 600 nm. One part of the radiation of both radiation transmitters is conducted via a measuring path, which is accessible to smoke, to one of the receivers constituting a measuring radiation receiver, and another part of such radiation is conducted via a comparison path, which is not accessible to smoke, to the other of the receivers constituting a comparison radiation receiver.

Abstract: An aerosol detector, for instance a transmission measurement path in a measurement chamber, is provided for the detection of a foreign component in a gas, for instance of incendiary aerosols or smoke in air, and communicates with a reference chamber containing aerosol-free reference gas. The gas in the measurement chamber is periodically exchanged for uncontaminated gas from the reference chamber by a periodical volume alteration of the reference chamber so that, in the presence of aerosols, the aerosol concentration in the measurement chamber and the output signal of the aerosol detector are modulated. The modulation, i.e. the variable portion of the output signal, is an indication of the aerosol concentration or the smoke density. A particularly suitable application is smoke detection in air for the purpose of fire or incendiary reporting or for monitoring air pollution.

Abstract: A light extinction type smoke detector which uses simple pulsed light or modulation pulsed light to reduce energy consumption, and precisely discriminates smoke generated by fire from extraneous interruption of the light beam from the light source to the photoelectric element to prevent a false alarm.

Abstract: A smoke detector is disclosed containing a radiation source and a radiation receiver arranged externally of a direct radiation region of the radiation source. In the presence of smoke or other combustion particles in the radiation region the radiation receiver is impinged by scattered radiation. The smoke detector contains optical elements which can be altered by external mechanical actuation, by means of which it is possible to alter in a predetermined manner an output signal of the radiation receiver. In this regard it is possible to either mechanically alter the solid angle which is so-to-speak viewed by the radiation receiver or the solid angle irradiated by the radiation source. The constriction of the active solid angle is preferably accomplished by a diaphragm or membrane displaceable along the radiation direction.

Abstract: The present invention provides an improved intrusion detection system of the type in which interruption of a beam of infrared energy transmitted from a transmitter to a receiver generates an alarm signal. The receiver includes a light source which remains unlighted when the transmitter and receiver are properly aligned but will be continuously lighted if either the beam is interrupted or the receiver and transmitter are not aligned. In one aspect of the invention, flasher circuitry in the receiver causes the light source to flash when the transmitted beam is only marginally aligned with the receiver. In another aspect of the invention, a lens in the receiver for focusing infrared radiation on a photodetector is movably mounted and accessible from the outside of the receiver to properly align the transmitted beam with the receiver without dismounting the receiver or requiring the use of any special alignment tools.

Abstract: A passive infrared intrusion detector is configured to resemble an electrical wall outlet. The unit includes a light for visually indicating the direction of its beam of sensitivity, and a lens unit which facilitates directional adjustment of the beam.

Abstract: A smoke detector contains a pulse-operated radiation source and a radiation receiver arranged externally of the region directly irradiated by the radiation source. The radiation receiver, in the presence of smoke in the radiation region, is impinged by scattered radiation and delivers output pulses. There is provided an evaluation circuit which generates a blocking pulse, and which inputs a resetting signal to a counter device in consequence of the difference of the blocking pulse and output pulse of the radiation receiver. The counter or counting device, in the absence of a resetting signal, is switched further and upon reaching a predetermined counter state triggers an alarm signal. High-frequency electrical disturbances which arise, as long as the radiation source delivers radiation pulses, at most can generate an additional resetting signal for the counter, so that the integrity of the smoke detector against triggering of false alarms is enhanced.

Abstract: A passive infrared intrustion detector is provided with a lens which has a plurality of first lens segments, each for focusing infrared radiation from various beams of sensitivity onto an infrared detecting element. Associated with each of the first lens segments is a second lens segment, with a displaced lens center, which serves to focus light originating within the detector device into a radiated beam, which corresponds in space to the region of sensitivity of the infrared beams.

Abstract: A smoke detector containing at least one smoke measuring chamber which possesses a mounting or socket plate having an upper surface intended to be mounted at the ceiling of a room or other appropriate area to be monitored and a housing enclosing the smoke measuring chamber and suspendingly secured at the socket plate. The housing possesses openings for the entry of the ambient air into the smoke measuring chamber. The smoke detector comprises a manually adjustable device by means of which it is possible to change the air entry opening in a manner such that the smoke detector can be accommodated to different environmental or ambient conditions, especially those containing different quantities of dust and other contaminants. A hood ring member, movably supported at the inside of a sleeve member of the smoke detector, can be selectively displaced in order to change the air entry openings.

Abstract: In a passive infrared intrusion detector there is provided an alarm indicator light with a light conduit for providing the emitted light to an opening on the wall of the detector. The end of the light conduit adjacent the opening is shaped to provide shaping of the emitted light.

Abstract: A radiation detector contains a sensor element constituted by a pyroelectrical element, for instance formed of lithium-tantalate, lead-zirconate-titanate, lead-zirconate-iron-niobate or polyvinyldifluoride. Arranged forwardly of the sensor element is a filter combination constituted by a first filter element comprising a germanium or silicon filter having vapor-deposited thereon a narrow band filter having a transmission or throughpass maxima at about 4.3-4.4 .mu.m, and a further filter element formed of sapphire or rutile or a calcium aluminate-, germanate- or a magnesium-fluoride glass. This filter combination has a transmission maxima at the resonance radiation of carbon dioxide at 4.3-4.4 .mu.m, while all other wavelength regions are damped by a factor of more than 1000. Furthermore, there can be provided an additional or auxiliary filter which absorbs radiation in the region of 3.5-4.0 .mu.m transmitted by the narrow band filter in the presence of angular or oblique incidence of such radiation.

Abstract: A passive infrared intrusion detector is provided with a lens having selectable patterns of sensitivity. The lens unit can be mounted to the detector in two orientations to provide two different patterns of sensitivity.

Abstract: A passive infrared intrusion sensor is provided with a cover which can be mounted in a closed or partially open position. In the partially open position a tamper switch is activated to illuminate a beam locator light within the detector.