Abstract: An enviromental abnormality alarm apparatus includes a plurality of terminals connected to a transmission line and a central processing unit. A specific address is assigned to each of the terminals. The central processing unit sequentially circularly accesses the addresses of the terminals and receives a signal corresponding to a physical change such as a fire, gas leakage, or burglary supplied from each terminal. Each terminal includes an alarm determination reference setting unit, a comparator for comparing the physical change signal with an alarm determination reference value, and an output unit for supplying a comparison result from the comparator. The alarm determination reference value of the alarm determination reference setting unit is set by transmitting and receiving data to and from the central processing unit.

Abstract: An environmental abnormality detection apparatus includes a detector for detecting environmental changes by monitoring physical changes in the environment and generating an output signal upon the detection of such an abnormality, a signal processor which generates an environmental abnormality signal based on the output of the detector, and a switching circuit connected between a pair of power source/signal lines. The apparatus further includes an oscillator and a control circuit which generates a signal for controlling the switching circuit obtained by the product of an output from the oscillator and the output of the signal processor. A power source is charged from the power source/signal lines, and supplies power to the detector, the signal processor and the oscillator.

Abstract: A separation type light blocking smoke detector detects smoke present between a light emitting section and a light receiving section spaced therefrom by detecting blocking of light between the light emitting section and the light receiving section. The detector includes a light emitting section driving circuit, a counting circuit, and a storage circuit. The light emitting section driving circuit changes the emission intensity of the light emitting section in accordance with a predetermined changing mode for every repetitive cycle. The counting circuit includes a first comparator and an updating signal generator, and counts a physical amount corresponding to a period during which an output from the light emitting section falls in a predetermined range for each repetitive changing cycle. The storage circuit includes a second comparator and an AND gate, and stores a count value of the counting circuit in an arbitrary repetitive cycle.

Abstract: A fire alarm apparatus includes a fire receiver, a pair of transmission lines extending from the fire receiver, a series of nonpolar fire detectors connected to the transmission lines, and a terminating unit, connected to the end terminals of the transmission lines, the terminating unit having an impedance element including a polar element. Each fire detector includes polarity inverting circuitry which includes a limit switch, arranged at a socket portion of the detector, and having a switch lever which is actuated by the detector body engaging with the socket portion; and diodes for inverting the polarity of the pair of transmission lines in synchronism with actuation of the switch lever. The polarity of the transmission lines after a detector is inverted when a detector body is detached from that detector.

Abstract: A detector system having multiple sensors, each sensor detecting a different danger condition, has an address comparator for determining whether an access address coincident with a selected address is present in an access signal received from a central monitoring unit. The detector exchanges an information signal with the central monitoring unit using the coincidence detection signal of the address comparator. Success coincidence detection signals, corresponding to successively selected addresses being present in the access signal, are counted by a counter. If the detector has two sensors, the counter may be a D flip-flop circuit, and if the detector has more than two sensors, the counter may be a ring counter. The counter generates a signal for operating respective analog switches connected to the outputs of each sensor so as to successively through-connect the output of one sensor to the output of the detector system for transmittal to the central monitoring unit.

Abstract: An environmental abnormality detecting apparatus for detecting abnormality in atmosphere such as heat, smoke, and a gas. A sampling circuit is provided for periodically sampling analog signals from a detector for detecting these phenomena. A quantizer quantizes sampled signals with step levels. An accumulator having a plurality of counters provides different accumulation times corresponding to the step levels. Reliability in accumulation effect is not degraded, and an abnormality signal can be detected in a short period of time when a degree of abnormality is high.