Abstract: A passive infrared intrusion detector is provided of the type having an infrared sensor for detecting a change in temperature in the field of view of the sensor caused by an intruder moving therein, optical means for focusing radiation from the field of view on the sensor, and an alarm which is activated when the sensor detects a change in temperature. The improvements reside in mounting the passive intrusion detector in a generally C-shaped housing exposed to a field of view which may be shifted through an angle of at least 180.degree.. A bendable, translucent window is provided having slots in opposite ends thereof which engage projections on opposite sides of the housing. The window is very simply released by applying thumb pressure to the window in the proximity of the projections. The intrusion detector is also provided with a horn-like enclosure which surrounds the sensor. A flexible Fresnel lens may be rapidly mounted on the enclosure, permitting ready adaptation of the detector to local conditions.

Abstract: A metal-oxide semiconductor, which is heated to different temperatures, is used in conjunction with an electronic circuit for reducing false alarms caused by spurious gases in gas warning installations and for determining the composition of a gas mixture. The temperature of the metal-oxide semiconductor, after reaching a predetermined value (T), is altered by an amount (.DELTA.T) either towards the positive or negative side or towards both the positive and negative side, respectively. The thus caused change in the conductivity of the metal-oxide semiconductor is evaluated in a comparator and in circuits for the different peak values of the gas components.

Abstract: An infrared intrusion detector wherein a plurality of separate radiation receiving regions or fields of view are focused by a single focusing optic, for instance a reflector or a Fresnel lens upon a single sensor element through an elongate or lengthwise extending radiation collecting element. The radiation collecting element can be constituted by an internally metal coated tube or a transparent body having a reflecting surface layer or coating, wherein the reflection coating is interrupted by radiation inlet openings. The infrared radiation which is focused by the focusing optic enters through such openings into the interior of the radiation collecting element and arrives, after having been reflected a number of times, at the sensor element which is mounted at an end side thereof.

Abstract: The optical arrangement for an infrared intrusion detector containing a plurality of separate radiation receiving regions or fields of view is provided with a first focussing optic or optical system, for instance a Fresnel lense which receives with its entire surface or area the infrared radiation which arrives from all of the receiving regions and delivers such received radiation to a multiplicity of further focussing means, for instance to individual reflectors. These reflectors are correlated in each instance to one of the receiving regions or fields of view and focus the radiation arriving from such receiving region upon a sensor element. In this way there is attained the beneficial result of optimum utilization of the infrared radiation which is available and the sensitivity of the infrared intrusion detector can be increased. The dimensions of the optical arrangement and the intrusion detector can be maintained small and relatively imperceptible.

Abstract: An infrared intrusion detector, utilizing as a sensor element a pyroelectric detector element, accomplishes evaluation of the output signal of the detector element with a charge amplifier, for instance by means of a capacitive feedback coupled operational amplifier, the output signal of which is reset at certain time intervals. The evaluation circuit operates independently of the detector capacitance and therefore enables optimum utilization of the pyroelectrical properties. By virtue of the short-circuit operation and the low ohmic properties of the circuit there is obtained a particularly good non-sensitivity against external disturbances and low noise and increased sensitivity.

Abstract: A radiation detector containing as the radiation sensor a pyroelectrical element, for instance, lithium-tantalate or lead-zircanate-titanante. Arranged forwardly of the sensor element is a filter combination composed of a quartz filter element having a vapor-deposited narrow band filter layer with a throughpass maxima at about 4.3 .mu.m and a germanium filter element. This filter combination displays a sharp throughpass maxima at the resonance radiation of carbon dioxide at 4.3 .mu.m, whereas all other wavelength ranges greater by the factor 100 or 1000, respectively, are damped.

Abstract: A fire alarm installation possessing increased intelligence which enables differentiating between smoldering fires and fires having open or licking flames. This capability is obtained in that the fire alarm installation possesses two sensor elements working according to different functional principles and an evaluation circuit contains circuit elements which form the quotient of the signals received from both sensor elements. The different sensor elements can be united in a single fire alarm housing which simultaneously contains the evaluation circuit.

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: A gas sensing signaling system is provided in which a plurality of gas sensing units are connected over cables with a central station. To permit establishment of threshold levels such that false alarms are rejected while the system still remains sensitive to dangerous conditions and to permit ready supervision and testing of said system, a central station is provided in which timing circuits are included which start the time interval upon sensing of an alarm condition above a lower, or warning threshold level. If the lower warning level signal persists for the timing interval--for example for about one-half minute, a warning signal is given. A higher level signal generates an alarm signal, either immediately or after a much shorter time delay. The circuit includes self-holding circuitry so that, once a sensing unit transmits a sensing signal which persists beyond the previous predetermined warning or alarm time duration, the central station will indicate the respective conditions until manually reset.

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 openings 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.

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: An ionization smoke detector containing at least one ionization chamber operated at an extra low voltage or potential. The ionization chamber contains a sensor employing a measuring electrode and a counter electrode. Ambient air has practically free access to the ionization chamber and there are provided one or more radioactive sources for generating ions, a supply voltage source and an electrical circuit for triggering an alarm. The smoke detector possesses increased operational reliability since circuit elements are provided which enable signal reporting to a central station by means of a low-voltage of about 200 volts, however the sensor is operated at an extra low voltage.

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 gas sensing unit designed to be protected against explosions and serving for the detection of combustible gases in an atmosphere, containing a gas sensor functioning according to the principle of catalytic oxidation or a semiconductor gas sensor. The gas sensing unit contains, within a housing, at least two mutually separated chambers or spaces. The one chambr is a compression-proof space and contains an electronic evaluation circuit for the gas sensor, the other chamber, which is a space structured to be protected against explosions, contains the gas sensor and a balancing element and is separated from the atmosphere by a sintered metal bushing or sleeve. A third explosion-proof chamber or space can be provided in the gas sensing unit for the purpose of connecting the lines or conductors. The gas sensor together with the balancing adapter forms an assembly or unit which can be pluggably arranged in the cover of the chamber containing the electronic system or hardware.

Abstract: A smoke detector containing a radiation source operating in a pulsed mode and a scattered radiation receiver connected in a coincidence circuit. This circuit contains a counter which counts both the radiation pulses and the incoming scattered radiation pulses. With undisturbed operation this counter, following each radiation pulse, has an even numbered counter state. The appearance of an uneven numbered counter state is indicative of the presence of spurious pulses and leads to resetting of the counter to null, so that there is prevented attainment of a counter state adequate for tripping an alarm signal. On the other hand, with the presence of a predetermined even numbered counter state there is triggered an alarm. Such smoke detector is almost immune to spurious pulses and does not tend to trigger faulty alarm signals.

Abstract: The oscillations which are generated during an attempted instrusion at a protected area or surface, for instance a vault wall or fence, are received at a sonic receiver and processed by an evaluation circuit such that only the oscillations emanating from an intrusion attempt trip an alarm, not however spurious oscillations from the surroundings. The received oscillations are mixed with a carrier frequency whose frequency periodically and continuously passes through a certain frequency range. The mixed signals are filtered in a narrow band frequency range, so that at the output, during each frequency through pass period, there appears the entire frequency spectrum of the received sonic oscillations in the evaluated frequency range. The filtered signals are integrated and the integrated signal, after a brief period of time, is reset as a frequency throughpass if no further signal appears.

Abstract: A release mechanism for opening a valve of a fire extinguishing installation by means of a linearly movable release element, such as a release plunger or release pin upon releasing a pre-stressed helical spring. At one end of the helical spring there is arranged a movable ball pressure plate. Between this ball pressure plate and a further fixedly arranged ball plate there are arranged balls or spherical elements. A loading pin provided at the movable ball pressure plate retains the helical spring under torsional stress and the movable ball pressure plate in such an angular position that the balls of both ball pressure plates can be retained at a starting distance. Upon electromagnetic release of the loading pin and return rotation of the helical spring the movable ball pressure plate rotates such that the spring can be axially relaxed or load-relieved and the release plunger or the like presses upon the release element of the valve and opens the latter.

Abstract: In a fire alarm or detector where radiation in the visible or infrared spectral range, is transmitted in a pulsed mode in a measuring chamber, there is provided an acoustical receiver which collects the air pressure vibrations arising upon absorption of the radiation pulses by smoke or aerosol particles and evaluates them in coincidence with the radiation pulses. Upon exceeding a certain intensity of the acoustical pulses there is triggered a fire alarm signal. In this way it is particularly possible to positively detect smoke which is intensively radiation absorbent and with increased sensitivity within a measuring chamber having small dimensions. A further development of the invention contemplates the provision of an additional scattered radiation receiver, preferably registering smoke having markedly scattering properties for the radiation. The acoustical and the scattered radiation-evaluation channel are connected in an OR-circuit with the alarm signal transmitter.

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 useful signals for an alarm means. The second circuit senses spurious emission produced by a thermal radiator. The first circuit is sensitive to the wavelength range of the flame below 6 .mu.m and the second circuit is sensitive to the wavelength range of a long-wave spurious emission above 6 .mu.m. A connecting means interconnects the first and second circuits in such a way that, while taking account of the statistical distribution of the flame emission and the spurious emission, an output signal is produced in such a way that the further transmission of the signal of the first circuit is blocked if a unidirectional output signal of the second circuit occurs at the same time, whereas it is transmitted to the alarm means if the output signal of the second circuit is absent or does not occur unidirectionally.

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.