Abstract: A radio alarm system for detecting abnormalities such as a fire having a central unit which is adapted to receive and decode the radio signal transmitted from each terminal device and to give an alarm and a plurality of terminal devices which is connected to a detector for detecting an abnormal state and is adapted to transmit information in the form of a radio signal based on an abnormality detection signal from the respective associated detector. And delay times which vary from terminal device to terminal device are set, and the selection of a free channel for transmission is effected in each terminal device by performing carrier sensing over a delay time peculiar to that terminal device.

Abstract: A sprinkler head of the present invention comprises a cover plate which is operated to fall down at a temperature lower than the operating temperature of the sprinkler head body and a switching unit provided on the body side of the sprinkler head so as to detect the falling of the cover plate and send a fire detection signal.A sprinkler head comprises a switching unit provided on the side of the sprinkler head body so as to send a fire detection signal when the unit is operated at a temperature lower than the operating temperature of the sprinkler head and send a sprinkler head operation signal when it is returned to a non-operating state by detection of the firewater discharged by the operation of the sprinkler head after the fire detection signal has been sent.

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 fire alarm system, sensor and method for determining a fire by detecting a change in a temperature, smoke density and/or gas concentration due to a fire. The detection data values of the respective analog sensors are corrected based on areas of supervisory regions of the respective analog sensors which are defined by walls, beams or inwardly extending projections surrounding the respective analog sensors, and/or heights from the floor of the respective analog sensors. The fire determination is carried out based on the corrected data.

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: An automatic fire extinguishing system wherein at least two fire detecting sensors are provided. The sensors are disposed at a distance from each other and movable in the horizontal and vertical directions to scan the region to be protected for detecting the angles of a fire source in the horizontal and vertical directions. A distance to the fire source is obtained from the angles of the fire source detected by the respective sensors. A discharge nozzle is set based on the fire source position determined by the angles and the distance of the fire source.

Abstract: A flame detecting apparatus and a flame detecting method which utilizes a flame detector having a directivity and provided with a photodetector such as a photodiode or a phototransistor which produces a photo-output in response to the intensity of light incident thereupon. The flame detector is scanned sequentially in the horizontal and the vertical direction within a supervisory region. When a photo-output from said flame detector obtained in the horizontal or vertical scanning by said scanning means exceeds a predetermined threshold value, one of the horizontal and the vertical scanning is suspended, while repeating the other, vertical or horizontal, scanning at the same horizontal or vertical position several times. Flame determination is made when the changes in the photo-outputs, which is obtained through the repeated scanning, exceed a predetermined value and they last over a predetermined scanning angle.

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: Apparatus for monitoring the fire extinguishing condition of automatic fire extinguishing equipment which is adapted to detect flames and spray a fire extinguisher liquid from a nozzle to extinguish a fire. The apparatus comprises a detector for generating a signal corresponding to the light energy radiated by the flames and a fire determination circuit for determining that the fire extinguisher liquid is hitting the flames when the detector signal has a DC component but has no AC component, since the AC component corresponds to flicker of the flame and ceases when the fire is sprayed with the fire extinguisher liquid.

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 scattered light type smoke detector wherein a light source and a photo-cell are so disposed that light from the light source does not directly enter the photo-cell and the photo-cell is adapted to receive light from the light source scattered by intervening smoke to detect the presence of smoke. The photo-cell is accommodated in a cylindrical recess formed in a smoke detecting holder. The inner face of the cylindrical recess and the surface of the smoke detecting holder extending along the optical axis of the photo-cell has light traps formed in sawteeth configuration in section for reflecting light other than the scattered light to be detected into a direction not towards the photo-cell.

Abstract: A fire alarm system having a plurality of fire detectors connected in parallel with each other to a pair of power/signal lines leading to a central signal station and adapted to respond to the signal station with a detection signal in the mode of current and controlling the signalling between the fire detectors and the signal station. The detection of a fire is accomplished by computing a difference between a steady-state current flowing through the signal lines and a detection current which are detected in an analog amounts. Each of the fire detectors is called by a simple calling clock pulse whose transmitting timing is controlled by a microcomputer of the central signal station to transmit a detection data. The generation timing of the calling clock pulses is freely selectable to effect a desired control of the fire detectors.

Abstract: A plurality of fire detectors for detecting a physical change caused by fire and a central signal station for receiving a fire signal from the fire detectors to raise an alarm are connected to each other through optical fiber cables. The central signal station transmits power light for supplying power and timing signals which are superposed on the power light for controlling operation timing to the respective detectors through the optical fiber cables, while each of the fire detectors converts the power light into electric power, carries out a fire detecting operation in response to the timing signals and transmits, upon detection of a fire, a fire signal in the form of light to the central signal station through the optical fiber cable.

Abstract: A photoelectric smoke sensor wherein a photo diode having a junction capacitance of 100 pH or less is employed and a resistor having a high resistance value of the order of mega-ohms is connected in series with the photo diode to obtain a photo output through the resistor, so that the voltage of the photo output may be sufficient to be directly subjected to comparison by the comparator without high-gain amplification even if the driving current for a light emitting diode is reduced. This enables omission of a high-gain amplifier and accordingly enables omission of a shield case for the circuits of the sensor which has been required to eliminate noises.

Abstract: A fire detector and a fire alarm system wherein a plurality of fire detectors are connected across a pair of lines leading to a signal station and which is capable of detecting, at the signal station, removal of a detector head or heads from an associated socket or sockets of any one or more detectors and yet capable of keeping the succeeding fire detectors operative to send a possible fire alarm signal even after removal of the head or heads. Each of said fire detectors comprises a means for disconnecting the line connected therethrough to the succeeding detector, temporarily in the course of removal of the detector head or heads from the associated socket or sockets or periodically after the detector or detectors has or have been removed from the associated socket or sockets. The signal station comprises a means for detecting the temporary or periodical disconnection of the line.

Abstract: In an alarm system utilizing a bidirectional wired television system, there are provided a plurality of alarm signal generators which are located on the subscribers' side, the signal generators generating low frequency alarm signals of the frequencies common to respective group units, the frequencies being different for respective subscribers in respective group units, each alarm signal generator being provided for each subscriber's modulators for respective group units; modulators for respective group units for modulating the low frequency alarm signals from the alarm signal generators with different high frequency carrier signals, and a receiving panel for receiving the modulated alarm signals.

Abstract: A smoke detector is disclosed which comprises an inner electrode, an intermediate electrode with a hole for passing radioactive rays therethrough, an outer electrode having openings for allowing smoke to flow therethrough, and one radioactive source, the inner and intermediate electrodes forming an inner ionization chamber, the intermediate and outer electrodes forming an outer ionization chamber, the radioactive source being disposed in the inner ionization chamber. A proper quantity of radioactive rays from the radioactive source is applied into the outer ionization chamber through the hole provided in the intermediate electrode.

Abstract: A smoke detector is disclosed which comprises an inner electrode, an intermediate electrode with a hole for passing radioactive rays therethrough, an outer electrode having openings for allowing smoke to flow therethrough, and one radioactive source, the inner and intermediate electrodes forming an inner ionization chamber, the intermediate and outer electrodes forming an outer ionization chamber, the radioactive source being disposed in the inner ionization chamber. A proper quantity of radioactive rays from the radioactive source is applied into the outer ionization chamber through the hole provided in the intermediate electrode.