Matsushita Electric Works, Ltd.

Kazumasa Murakami

Motoharu Terada

Kiyoshi Yamada

Masaichi Fukunaga

A building automation system is constituted by a distributed process controller which includes a common platform, per-usage package, and common function package, and the common platform is provided with a mechanism which can standardize a service program for operating and controlling hardwares mainly with CPU irrespective of their scale and usage and can prepare all data transmission for local transmission with the same program function, the mechanism being commonly utilizable in air conditioning and fire alarm system, to render the administration system easily expandable and flexible in system arrangement.

Building automation system using common platform program and common

An improved fire alarm system utilizes receiver and fire detecting terminals connected thereto through a signal transmission line comprising two wires. The fire detecting terminal operates on two mode, one being a contact-closure mode of transmitting to the receiver a level signal whether or not a significantly higher fire-indicative quantity is detected, and the other being intelligent mode of transmitting a digital signal indicative of the sensed quantity in the form of a superimposed signal upon the level signal in answer to the instruction from the receiver for precise and convenient analysis thereof in determining fire presence on the side of the receiver. The fire detecting terminal includes a comparator having its own threshold with which the value of the sensed analog quantity is compared for providing the level-shifted signal when the sensed analog quantity has a level higher than the threshold, notifying fire presence independently of the intelligent mode. The threshold level can be selected independently of a criterion utilized in determining first presence based upon the digital signal on the receiver, so that the above two modes can have the same sensitivity against possible fires. Accordingly, the contact-closure mode can well stand for a back-up fire detection without reduction in sensitivity.

Fire alarm system

A signal transmission system for transmitting a first signal and a second signal superposed thereupon through a common signal transmission line composed of two wires. A plurality of terminal units are connected through the common signal transmission line to a central unit and are connected in parallel with each other across the two wires of the signal transmission line. At least one of the terminal units transmits the first signal in the form of a level signal; and at least one of the terminal units transmits or receive the second signal in the form of a superposed signal on the level signal. The central unit transmits and receives the superposed signal as well as receives the level signal for receiving data or information respectively from the above terminal units. Accordingly, both the first and second signals of different types and therefore carrying different information can be transmitted between the central unit and the respective terminal units through the common signal transmission line.

Signal transmission system featuring bidirectional transmission of

A novel fire alarm system with a plurality of smoke detectors which are adapted to be installed in different locations are connected through a data transmission line to a receiver where the smoke density signals transmitted from the respective smoke detectors and indicative of the density of smoke in the corresponding locations are processed for determination of fire presence. The receiver is provided with fire judging circuit which identifies the presence of fire only when the smoke density detected by any one of the smoke detectors exceeds a reference density level and when such smoke density lasts over a reference time period. Thus, the information from each smoke detector is analyzed with respect to the smoke density and the time period over which the smoke density of significant level lasts. Accordingly, a reliable detection of fire is effectuated. Also incorporated in the system is a selector by which said reference density level can be selected from a plurality of predetermined density levels of different values and by which the reference time period can be selected from a plurality of predetermined time periods of different values. Consequently, the criterion which is the combination of the smoke density and the related time period for determination of fire presence can be variably set depending upon the differing conditions of the locations under surveillance, enabling the system to be easily and successfully adapted for use in different fire monitoring conditions.

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Kadoma, Japan

Kazumasa Murakami