Communications: electrical – Condition responsive indicating system – With particular system function
Reexamination Certificate
1999-05-14
2001-02-27
Pope, Daryl (Department: 2736)
Communications: electrical
Condition responsive indicating system
With particular system function
C340S505000, C340S524000, C340S525000, C340S870030, C340S870030
Reexamination Certificate
active
06195003
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a fire alarming system.
2. Description of the Related Art
In a conventional fire detection system, a plurality of terminal devices such as a fire sensor, a transmitter, a manual box, or other devices to be controlled are connected to a fire alarming signal receiving device, and each terminal device is assigned its own address. The fire alarming signal receiving device calls terminal devices one after another according to the addresses. At a time, only the called terminal device can transmit information about itself (for example a fire alarming signal) to the fire alarming signal receiving device. This technique is known as polling. In this technique, a plurality of alarm signal lines are connected to the fire alarming signal receiver wherein a plurality of terminal devices are connected to each alarm signal line, and thus a great number of terminal devices are connected to the fire alarming signal receiver. The fire alarming signal receiving device calls these terminal devices one after another via a data processor provided in the fire alarming signal receiving device and acquires information about for example an event of a fire from each terminal device.
In the polling technique, however, any terminal device cannot send information to the fire alarming signal receiving device until it is called by the fire alarming signal receiving device. The calling period increases with the increase in the number of terminal devices connected to the alarm signal lines. If the terminal devices include such a device which should transmit information to the fire alarming signal receiving device in a predetermined time period after the event of information at that device, the maximum number of terminal devices which are allowed to be connected to the signal lines is limited by the above predetermined time period.
A specific example of a terminal device which should transmit information in a limited time period is a manual box. When a fire occurs, if one presses a button or the like of a manual box, the manual box transmits an alarm signal to the fire alarming signal receiving device. The fire alarming signal receiving device transmits a response signal to the manual box thereby indicating that the fire alarming signal receiving device has received the alarm signal. If the manual box receives the response signal, the manual box turns on a response lamp or the like provided on the manual box thereby indicating that the alarm signal was generated by that manual box.
In the worst case, the time required for the response lamp of the manual box to be turned on after the manual box was activated becomes as long as one polling period. If the waiting time from the activation of the manual box to the turning-on of the response lamp is so long, the person, who activated the manual box, will wonder if the fire alarming system is in correct operation. To reduce the waiting time to a desirable level, it is required that the number of terminal devices connected to one signal line be limited to a not large value.
One known technique to ease the above limitation is as follows. A fire alarming signal receiving device sequentially calls a plurality of terminal devices connected to signal lines extending from the fire alarming signal receiving device and acquires information about the status of each terminal device wherein a higher transmission priority is given to the particular information of terminal devices having a manual box and the information of these terminal devices is transmitted before other information. If the fire alarming signal receiving device receives the particular kind of information from a manual box, fire alarming signal receiving device preferentially calls those terminal devices having a manual box before calling other terminal devices and determines which manual box has been activated.
In the conventional technique, as described above, when the fire alarming signal receiving device receives the particular kind of information from a terminal device having a manual box, the fire alarming signal receiving device calls the terminal devices having a manual box one by one to determine which manual box has been activated. Therefore, the fire alarming signal receiving device still requires a long time to determine which terminal device having a manual box has been activated, and thus the terminal device still requires a long time to turn on a lamp for indicating that the fire alarm signal has arrived at the fire alarming signal receiving device, in particular when there are a great number of terminal devices having a manual box.
One possible technique to solve the above problem is to call at the same time all terminal devices having a manual box instead of calling them one by one when the fire alarming signal receiving device receives the particular kind of information from a terminal device having a manual box. In response to the call from the fire alarming signal receiving device, the terminal device whose manual box is in an activated state transmits the signal to the fire alarming signal receiving device. Thus, it is possible to reduce the time from when the manual box is activated until the terminal device turns on the lamp to indicate that the fire alarm signal has arrived at the fire alarming signal receiving device.
However, the above modification leads to another problem. That is, if a plurality of manual boxs are activated at substantially the same time, the terminal devices having these manual boxs respond at the same time. As a result, signals collide with each other, and the fire alarming signal receiving device cannot determine correctly which manual box have been activated.
Furthermore, in the conventional polling technique, the data transmission rate over the alarm signal line should be high enough to acquire the information from a large number of terminal devices in a limited time period as short as for example 5 sec. Therefore, the transmission line is required to have a large number of parallel bit lines, which result in an increase in cost.
In a known technique proposed to solve the above problem, the plurality of terminal devices are divided into groups and an idle period is provided between signals calling the adjacent groups so that in the idle period a terminal device can transmit an interrupt signal to the fire alarming signal receiving device wherein it is possible to determine which group the terminal device belongs to from the interrupt signal. If the fire alarming signal receiving device receives an interrupt signal, the fire alarming signal receiving device calls, one by one, preferentially the terminal devices belonging to the group determined from the interrupt signal.
However, in this polling technique in which if a terminal device detects an event of a fire, it transmits in an idle period to the fire alarming signal receiving device an interrupt signal with information (such as a group number) indicating which group the terminal device belongs to, and the fire alarming signal receiving device calls the terminal devices in that group one by one, still a long time is required to determine which terminal device has detected the event of the fire, in particular when each group includes a large number of terminal devices.
A fire alarm/security system is also known in which a fire alarming signal receiving device polls terminal devices such as a fire sensor, a smoke exhausting system, a fire extinguishing system, and a burglar alarm system, or transmitters connected to these terminal devices, and the called terminal devices transmit the information representing the status to the fire alarming signal receiving device whereby the fire alarming signal receiving device acquires the monitored information. In this fire alarm/security system, control information is transmitted to the terminal devices called by the fire alarming signal receiving device.
In this type of fire alarm/security system, there is a possibility that an error occurs during the transmission between the fire alarming s
Hirooka Eiji
Ichikawa Nobuyuki
Takahashi Keiichi
Takeyoshi Kenji
Nohmi Bosai Ltd.
Pope Daryl
Wenderoth , Lind & Ponack, L.L.P.
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