Terminal sensing device for a disaster prevention monitoring system

• US 5,715,177 A
• Filed: 06/28/1996
• Issued: 02/03/1998
• Est. Priority Date: 06/30/1995
• Status: Expired due to Term

• Current Assignee: Hochiki Corporation
• Original Assignee: Hochiki Corporation
• Inventors: Kojima, Yoshinori, Machida, Haruchika, Kii, Mashahiro
• Primary Examiner(s): Trammell, James P.
• Application Number:
  US08/671,675
• Time in Patent Office: 585 Days
• Field of Search: 364/550, 364/505, 364/506, 364/138, 364/185, 364/557, 340/501, 340/506-513, 340/517-524, 340/588, 340/825.56
• US Class Current: 702/62
• CPC Class Codes: G08B 17/00 Fire alarms; Alarms responsive to explosion
• CPC Class Codes: G08B 25/04 using a single signalling line, e.g. in a closed loop

Abstract

A transmission processing unit is disposed in a terminal sensing device for a disaster prevention monitoring system. The transmission processing transmits a detection data to a central unit of the system, only when the detection data is equal to or higher than a predetermined level threshold and a difference between the detection data and a detection data of a preceding transmission is equal to or larger than a predetermined level difference threshold ΔTH. Alternatively, the transmission processing unit transmits the detection data to the central unit of the system, only when the detection data is equal to or higher than the predetermined level threshold and a time period which is elapsed after the transmission of the preceding detection data is equal to or longer than a predetermined time period threshold.

Claims

1. A terminal sensing device for a disaster prevention monitoring system, which is connected to a transmission path elongating from a central monitoring device, said terminal sensing device comprising:

detecting means for detecting an analog detection signal; and

transmission processing means for judging at a predetermined period as to whether or not detection data obtained from said analog detection signal is equal to or higher than a predetermined level threshold and a difference between said detection data and a detection data of a preceding transmission is equal to or larger than a predetermined level difference threshold, and for transmitting the detection data to said central monitoring device, when the detection data is equal to or higher than the predetermined level threshold and said difference between the detection data and the detection data of the preceding transmission is equal to or larger than a predetermined level difference threshold.

2. A terminal sensing device for a disaster prevention monitoring system according to claim 1, wherein said transmission processing means comprises:

first comparison means for comparing the detection data to be transmitted with the level threshold at the predetermined period, and for outputting a first comparison output, when the detection data is equal to or higher than the level threshold;

second comparison means for comparing the difference between the detection data and the detection data of the preceding transmission with the detection data, when the first comparison output is outputted, and for outputting a second output, when the difference between the detection data and the detection data of the preceding transmission is equal to or higher than the level difference threshold; and

transmission means for, when the second comparison output is outputted, transmitting the detection data to said central monitoring device.

3. A terminal sensing device for a disaster prevention monitoring system according to claim 2, wherein said second comparison means calculates the level difference threshold in accordance with a predetermined function on the basis of the detection data, and compares the calculated level difference threshold with the detection data difference.

4. A terminal sensing device for a disaster prevention monitoring system, which is connected to a transmission path elongating from a central monitoring device, said terminal sensing device comprising:

detecting means for detecting an analog detection signal; and

transmission processing means for judging at a predetermined period as to whether or not detection data obtained from said analog detection signal is equal to or higher than a predetermined level threshold and a time period which elapses after a preceding detection data transmission is equal to or longer than a predetermined time period threshold, and for transmitting the detection data to said central monitoring device, when the detection data is equal to or higher than the predetermined level threshold and said elapsed time period is equal to or longer than the predetermined time period threshold.

5. A terminal sensing device for a disaster prevention monitoring system according to claim 4, wherein said transmission processing unit comprises:

first comparison means for comparing the detection data to be transmitted with the level threshold, and for outputting a first comparison output, when the detection data is equal to or higher than the level threshold;

second comparison means for, when the first comparison output is outputted, comparing the time period which elapses after a time of a preceding detection data transmission with a predetermined time period threshold, and for outputting a second comparison threshold, when the elapsed time period is equal to or longer than the time period threshold; and

transmission means for, when the second comparison output is outputted, transmitting the detection data to said central monitoring device.

6. A terminal sensing device for a disaster prevention monitoring system according to claim 5, wherein said second comparison means calculates the time period threshold in accordance with a predetermined function on the basis of the detection data, and compares the calculated time period threshold with the elapsed time period.