Nohmi Bosai Ltd.

Nobuyuki Ichikawa

Keiichi Takahashi

Eiji Hirooka

Kenji Takeyoshi

A fire alarming system includes a plurality of terminal devices including fire sensors, transmitters, manual boxes, and/or other devices to be controlled; and a receiving device to which the plurality of terminal devices are connected. A great number of terminal devices with a manual box are connected to the receiving device. When a plurality of manual boxes are activated at the same time, the terminal devices corresponding to the activated manual boxes can be called at the same time without encountering a collision among returning-back signals transmitted from these terminal devices. That is, when a plurality of manual boxes are activated at the same time, the signal of only one of the plurality of activated manual boxes can arrive at the receiving device.

Fire alarming system

A fire alarming system includes a plurality of terminal devices including fire sensors, transmitters, manual boxs, and/or other devices to be controlled; and a receiving device to which the plurality of terminal devices are connected. A great number of terminal devices with a manual box are connected to the receiving device. When a plurality of manual boxs are activated at the same time, the terminal devices corresponding to the activated manual boxs can be called at the same time without encountering a collision among returning-back signals transmitted from these terminal devices. That is, when a plurality of manual boxs are activated at the same time, the signal of only one of the plurality of activated manual boxs can arrive at the receiving device.

Light emitted from a light emitting element is converted into parallel light by a lens, and a light receiving element detects scattered light occurring due to particulate existent in a fan-shaped field pattern spreading along the optical path of the parallel light. Since parallel light is used, stray light can be processed within a limited space. Furthermore, since the scattered light of parallel light which occurs due to the particulate is detected using the fan-shaped field pattern, particulate detection can be performed on volumes of air at a high signal-to-noise ratio.

Particulate detecting sensor employing parallel light

An LD light-emitting circuit 2 comprises an analog multiplexer MP having a plurality of switches, and resistors R7, R8, R9 and R10 connected to these switches. When the temperature is not higher than a normal temperature, the resistor R7 is connected so that the amount of light emitted from the LD 1 is maintained constant. As the temperature rises, however, the resistor R8, R9 or R10 having increasing resistance is connected in response to a signal from a control circuit, in order to decrease the driving current that flows into the LD 1. This enables the LD 1 to suppress its own heating and to lengthen its life.

Growing community of inventors

Tokyo, Japan

Nobuyuki Ichikawa