Nohmi Bosai Ltd.

Nohmi Bosai Kogyo Co., Ltd.

Mikio Mochizuki

Hideo Ito

Makoto Yasukawa

Eiji Hirooka

Ryousaku Kobayashi

Tadao Morita

Yoshiharu Orioka

A fire detector capable of readily and accurately adjusting the sensitivity there of and of not erroneously outputting any fire signal is provided with a first-stage amplifying circuit having an output adjusting variable resistor and a fire discriminating section having a reference voltage adjusting variable resistor. As a result, it is possible to adjust the amplified output to a predetermined value by the switching level of the fire discriminating section to a predetermined value by the reference voltage adjusting variable resistor.

Fire detector

A fire detector capable of readily and accurately adjusting the sensitivity thereof and of not erroneously outputting any fire signal is provided with a first-stage amplifying circuit having an output adjusting variable resistor and a fire discriminating section having a reference voltage adjusting variable resistor. As a result, it is possible to adjust the amplified output to a predetermined value by the switching level of the fire discriminating section to a predetermined value by the reference voltage adjusting variable resistor.

A smoke detecting apparatus for a fire alarm has a smoke chamber into which smoke to be detected is introduced, a light emitting lamp disposed in the smoke chamber, a light receiving element disposed in the smoke chamber so as to receive the light emitted from the light emitting lamp, an amplification device for amplifying an output signal from the light receiving element, a detection device for detecting the density of the smoke on the basis of an output signal from the amplification device, a comparison device for comparing the value of the output signal from the amplification device with a fixed value, an abnormality output device for outputting an abnormality indication when the value of the output signal from the amplification device is judged to be smaller than the fixed value by the comparison device, an augmentation command switch for commanding augmentation of the value of the output signal from the amplification device, and an augmentation device for augmenting, in accordance with a command from the augmentation command switch, the value of the output signal of the amplification device which is input to the comparison device.

Smoke detecting apparatus for fire alarm

A photoelectric type fire detector includes self-testing capabilities. An upper level threshold limit and a lower level threshold define a predetermined range for output levels of an amplifier connected to an output of a light receiving element. In a self-test mode, a gain set in the amplifier is increased automatically. The number of times in which the amplifier output level deviates from the predetermined range is counted. If the deviation count exceeds a predetermined count threshold, it is determined that the photoelectric type fire detector is abnormal.

Photoelectric type fire detector

A smoke detecting apparatus for a fire alarm has: a smoke chamber into which smoke to be detected is introduced, a light emitting lamp disposed in the smoke chamber, a light receiving element disposed in the smoke chamber so as to receive the light emitted from the light emitting lamp, an A/D converting circuit for converting the output signal from the light receiving element into a digital signal, a memory for storing data therein, a computing device for storing in said memory, as first calibration data, the output data from the A/D converting circuit when the smoke chamber is filled with a first reference gas, storing in said memory, as second calibration data, the-output data from the A/D converting circuit when the smoke chamber is filled with a second reference gas, and computing a proper smoke density corresponding to the output data from the A/D converting circuit on the basis of the first and second calibration data and the output data from the A/D converter circuit, and a display device for displaying the smoke density computed by the computing device.

High sensitivity smoke detecting apparatus using a plurality of sample

A heat detector includes an external temperature detector for detecting an external temperature outside the heat detector and an internal temperature detector for detecting an internal temperature inside the heat detector. A microcomputer calculates a temperature difference between the external temperature detected by the external temperature detector and the internal temperature detected by the internal temperature detector. The microcomputer monitors the above-described temperature difference to detect an event in which the temperature difference has remained greater than a predetermined value for a predetermined duration or longer. If the microcomputer detects that the temperature difference has remained greater than the predetermined value for the predetermined duration or longer, the microcomputer outputs an abnormal signal representing that the external temperature detector is abnormal.

Heat detector including device for detecting abnormality of external

A smoke detecting apparatus includes a lamp, a light receiving element for receiving light from the lamp, and a smoke detecting circuit for detecting the smoke density in accordance with the signal outputted from the light receiving element. The apparatus further includes a light emission failure detector and counter for detecting a light emission failure in which the lamp fails to emit light in response to a light emission instruction from the smoke detecting and counting light emission failures, and a memory for storing the number of light emission failures. The apparatus may further include a warning unit which, when the number of failures becomes a predetermined value or more, warns that the lamp will soon be exhausted. Thus, the unit enables a maintenance person to replace the lamp without fail before it is exhausted.

A light-scattering-type smoke detector having a projecting element and a light receiving element surrounded by a labyrinth is disclosed wherein the labyrinth comprises an array of a plurality of light shielding columns arranged in a circle each having a substantially J-shaped cross section, and the head portion of each column is inclined relative to the bisector of an angle formed between the lines connecting a first reflecting point with the projecting and light receiving elements, the light shielding columns having darkly colored light reflective surfaces.

A labyrinthine light scattering-type smoke detector

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.

Growing community of inventors

Tokyo, Japan

Mikio Mochizuki