Abstract: Measuring stations or locations are connected in cascade to signal lines and transmit measured or measuring values to a central signal station at which the measured values are linked or appropriately processed so as to obtain distinct malfunction or alarm signals. Upon activation of the monitoring system all measuring stations are disconnected by a change in voltage appearing on the signal line. Then, the measuring stations are reconnected to the signal line in a timewise staggered fashion by means of switching elements present at each measuring station in such a manner that each measuring station additionally reconnects a subsequent measuring station to the line voltage after a predetermined time-delay. Address storages are present at the measuring stations and are charged or occupied in a predetermined sequence by the central signal station with addresses associated with the individual measuring stations.

Abstract: Due to aging of the insulating materials arranged between the electrodes in ionization fire alarms or detectors the insulating efficiency of these thus formed so-called insulating paths or spans deteriorates in the course of time despite, or maybe even due to the cleaning operations performed upon such ionization fire alarms. To ensure that the insulating capacity does not fall below a critical value the insulating path or span is formed by at least two different insulating materials. The materials are arranged in such a manner that the creepage path between the electrodes extends across all the different insulating materials. This principle also may be applied to other measuring devices which require a high input resistance of an amplifier stage.

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: 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: 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: 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: 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: In a fire alarm system individual fire alarms are connected in series by reporting lines with a central signal station. In order to be able to connect a greater number of fire alarms with the individual reporting or signaling lines and/or in order to be able to dispatch an increased amount of current through the reporting lines, the reporting or signaling lines from the last fire alarm of a line are returned back to the central signal station in the form of a ring circuit or loop. Upon the absence of signals at a reporting line an interrogation device is reversed, so that there can be ensured that in the event of a line disturbance or breakdown of a fire alarm the remainder of the fire alarms still can be utilized for giving a signal. The individual fire alarms are structured such that during assembly the inputs and outputs can be mutually interchanged.

Abstract: In an alarm installation containing a central evaluation unit and alarm devices arranged remotely therefrom, the transmission of energy from a radiation source and the reporting back of the signal occurs exclusively according to optical principles by means of radiation conducting elements, so-called light guides or conductors, by means of which the alarm devices are connected with the evaluation device. The alarm devices contain a preferably high-ohm sensor element, for instance a smoke-sensitive ionization chamber, whose operating voltage is infed by means of a solar cell which is irradiated by a light guide and whose output signal is fed back to the evaluation device by means of a high-ohm electrical transducer and a light guide. Such type alarm installation preferably is used for fire detection purposes, for gas, smoke temperature detection or intrusion protection, and is particularly suitable for use in an explosion-endangered environment or one subjected to electrical disturbances.

Abstract: A fire alarm is provided with a temperature sensitive element formed of a shape memory alloy, which following cold working, upon heating to a critical temperature, typically for instance about 70.degree. C., returns to the original impressed shape and also retains this shape even after subsequent recooling. Due to the movement of the element there is triggered a self-holding alarm signal, either directly by closing contacts or indirectly. Resetting of the fire alarm can be accomplished by mechanically cold working the element, or by using two-way shape memory alloys through cooling to a lower temperature threshold which can be below room or ambient temperature. A further beneficial construction is realized by combining the arrangement with a different type of fire detection or sensing element, for instance by arranging a shape memory alloy element in a scattered radiation-smoke detector.

Abstract: A smoke detector, especially for a fire alarm, comprising a radiation source possessing a substantially conical ring-shaped radiation characteristic or pattern and a radiation receiver arranged along the axis of the radiation source but externally of the direct radiation. The radiation receiver receives radiation which is scattered by smoke particles within the conical ring-shaped radiation region. In order to reduce the spurious radiation impinging on the radiation receiver the radiation region is bounded by elements located externally of the direct receiving region of the radiation receiver. Web means (which comprise the bounding elements opposite the radiation source) are provided which are specially-shaped to prevent dust from collecting on their radiation receiving surfaces, thereby keeping the smoke detector from becoming increasingly susceptible with time to the triggering of false alarms as the deposition of dust at the inner surface of the fire detector housing increases.

Abstract: The detector has first and second circuits which are interconnected. The first circuit senses the emission of a flame at least in the wavelength range of carbon dioxide and produces square-wave signals corresponding to the flicker frequency. The second circuit senses short wavelength emission with a wavelength shorter than 3 .mu.m and produces square-wave signals corresponding to the flicker frequency of the emission. The interconnecting means permits the alarm means to be activated only when the first circuit signals and the second circuit signals are present simultaneously and with the same direction, to indicate that the flicker frequency is the same for both emissions. An integrator prevents spurious coinciding signals from resulting in an alarm and a reset circuit periodically resets the integrator. Various specific photoelectric means are described.

Abstract: A smoke detector having a radiation source operating in the infrared, visible or ultraviolet wavelength region, transmitting radiation throughout an expanded or extended solid angle region of predetermined minimal extent. A radiation receiver is arranged externally of this radiation region for the reception of radiation which has been scattered at smoke particles and for signal transmission upon exceeding a predetermined smoke density. To compensate for decrease in smoke sensitivity of the smoke detector with temperature increase there is provided a bimetallic strip which, in the presence of a temperature increase, gradually moves into a small part of the radiation region and causes an additional irradiation of the radiation receiver. By suitable selection and arrangement of the bimetallic element the smoke sensitivity remains almost constant up to a predetermined critical temperature, or the smoke sensitivity gradually increases with increasing temperature.