Nohmi Bosai Ltd.

Nohmi Bosai Kabushiki Kaisha

Nohmi Bosai Co., Ltd.

Seiko Instruments Inc

Canon Kabushiki Kaisha

Kaoru Takahashi

Keiichi Takahashi

Yoshio Kinoshita

Ryuji Shutoku

Akio Tsumuji

Yukihiko Usami

Kouichi Hishino

Ryosuke Nagao

Akio Tsumiji

An object of the present invention is to provide a fire alarm system which is adaptable to form a large-size fire alarm system and is capable of causing a receiving portion to quickly detect fire information from a terminal unit, or the like, if the terminal unit has been operated. In a fire alarm system in which terminal units, such as fire detectors, are connected to the receiving portion, an address is given to the terminal unit to allow detection of terminal units that have a status change, wherein system polling or the like for a specific terminal unit, such as a transmitter, among the terminal units is performed prior to performing system polling of other terminal units.

Fire alarm system

A transmitter for use with a fire alarm system controls the monitoring of devices to be controlled based on a control command transmitted from a receiving section such as a fire receiver. With this transmitter, even if there is a short circuit in control lines for connecting the transmitter and the devices, it is not necessary to exchange fuses, and it is also possible to avoid the waste of power consumption which would otherwise incur during the actuation operation of the device(s). When the short circuit is recovered, the transmitter is able to correctly actuate the device(s). A small reverse current is permitted to flow in the control lines so as to enable the monitoring of a short circuit in the control lines by the transmitter. When the transmitter receives an actuation command from the receiving section, and if a short circuit in the control lines is detected, the transmitter goes into a standby state in which it holds an actuation signal for actuating the device(s) from being output to an actuating section. When the short circuit is recovered, the transmitter outputs the actuation signal to the actuating section.

A power supply control device is provided in a fire alarm system having terminals such as fire detectors and/or repeaters with comparators to detect abnormalities such as fire or an operating status of controlled apparatus, and is equipped with a reference voltage supply a source to supply reference voltage to the comparators, and a power supply control to allow the reference voltage to be supplied to the comparators only during the detecting time.

Power supply control device in fire alarm system

A line interruption supervisory device for a fire alarm system is capable of reliably carrying out the line supervision even if the line length is long and/or there is a large number of connected fire detectors. To this end, a terminating capacitor is connected across the terminal of a pair of power/signal lines to which fire detectors are connected. A memory first stores the voltage available on the power/signal lines when the line supervision is requested, immediately followed by the interruption by a cut-off circuit of the power supply to a pair of power/signal lines, and further followed by a comparison of the voltage available on the power/signal lines before the power supply interruption with a line voltage available after a lapse of a predetermined time from the power supply interruption by a line interruption discriminating circuit to determine, according to any difference between these voltages, whether there is an open power/signal line.

Line interruption supervisory device for a fire alarm system

A fire alarm system includes a receiver unit such as a fire control panel or a repeater having zone lines connected thereto, with various types of fire detectors being connected to the zone line. Supervising power is normally supplied to the zone lines. When the receiver unit receives a fire signal via a zone line from a fire detector, the receiver unit decides from what type of detector the fire signal was transmitted. Types of fire detectors include, for example, a type having as switching means only a mechanical contact for causing said zone line to be in a short-circuited condition, a type having as switching means a switching circuit with a self-holding function, or a type having a response lamp. In response to the receipt of the fire signal, either no power, or suitably reduced power or reduced constant current for the zone line to which the operated detector transmitting the fire signal is connected is supplied, depending on the type of detector that has operated, to thereby allow a reduction in power consumption.

A fire alarm system includes a receiver unit connected to a plurality of terminal unit groupings, each of the terminal unit groupings made up of a plurality of terminal units. The fire alarm system operates in one of a system polling mode, a point polling mode and a selecting mode. In the system polling mode, the receiver units polls all of the terminal units and provides a grouping response period in which each of the terminal unit groupings is permitted to respond to the receiver unit polling. If one of the terminal units of a particular grouping undergoes a status change, such a terminal unit transmits to the receiver unit a group response signal during the corresponding group response period. Then, the system enters the point polling mode, in which the terminal units of the terminal unit grouping corresponding to the group response period in which a group response signal was received are polled. During a corresponding terminal unit response period, the terminal unit having the status change transmits a terminal unit response period to the receiver unit. Thereafter, the fire alarm system enters the selecting mode, in which status information is transmitted to the receiver from the terminal unit having the status change.

A memory card for storing information having a shape similar to that of a credit card. The memory card includes a capacitor connected across power terminals of a RAM and a resistor connected between one power terminal of the RAM and an external terminal. A switch is connected in parallel with the resistor for short-circuiting the resistor. The switch is controlled in accordance with a signal from an external device. When the RAM is accessed by the external device, the switch is closed so that the impedance of the power supply line is decreased.

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Tokyo, Japan

Kaoru Takahashi