Alarm system

• US 7,193,513 B2
• Filed: 12/21/2005
• Issued: 03/20/2007
• Est. Priority Date: 09/19/2002
• Status: Expired due to Fees

• Current Assignee: Optex Company Limited (OPTEX GROUP Co., Ltd.)
• Original Assignee: Optex Company Limited (OPTEX GROUP Co., Ltd.)
• Inventors: Iwasawa, Masashi
• Primary Examiner(s): Hofsass; Jeffery
• Assistant Examiner(s): LAI, ANNE VIET NGA
• Application Number:
  US11/312,572
• Publication Number:
  US 20060097865A1
• Time in Patent Office: 454 Days
• Field of Search: 340/541, 340/539.1, 340/539.13, 340/539.16, 340/539.17, 340/572.1, 702/187
• US Class Current: 340/539.1
• CPC Class Codes: G08B 13/183 by interruption of a radiation beam or barrier
• CPC Class Codes: G08B 13/191 using pyroelectric sensor means
• CPC Class Codes: G08B 25/009 Signalling of the alarm condition to a substation whose identity is signalled to a central station, e.g. relaying alarm signals in order to extend communication range
• CPC Class Codes: G08B 25/10 using wireless transmission systems G08B25/009 takes precedence
• CPC Class Codes: G08B 29/24 Self-calibration, e.g. compensating for environmental drift or ageing of components

Abstract

A transmitter comprises a signaling history information transmission unit. After the transmitter generates a detection signal, the signaling history information transmission unit sends corresponding signaling history information to a regular signal transmission unit. From this regular signal transmission unit, the signaling history information and a regular signal are transmitted to a receiver. The signaling history information contains a count value which is updated at every transmission of the information. Even if the transmitter generates a detection signal during a communication failure, the receiver can identify a time when the transmitter generated the detection signal, based on a received count value.

Claims

1. An alarm system comprising:

a transmission system including

(i) a transmission circuit for generating and transmitting a detection signal upon detection of an object within a monitoring area, and

(ii) a transmission unit for

(a) producing at a predetermined time interval, after said transmission circuit generates the detection signal upon detection of the object in the monitoring area, signaling historical information that directly relates to the detection signal, and

(b) transmitting the signaling historical information independently of transmission of the detection signal by said transmission circuit; and

a receiving system for receiving the signaling historical information when transmitted by said transmission unit, and for generating an alarm signal upon receiving the detection signal from said transmission circuit.

2. The alarm system according to claim 1, wherein

said transmission unit is for producing signaling historical information that directly relates to the detection signal by producing signaling historical information that directly relates to the generation or transmission of the detection signal.

3. The alarm system according to claim 2, wherein

said transmission unit is for producing signaling historical information that directly relates to the generation or transmission of the detection signal by producing signaling historical information that directly relates to the generation of the detection signal.

4. The alarm system according to claim 3, wherein

said transmission unit is for producing signaling historical information that directly relates to the generation of the detection signal by producing signaling historical information that directly relates when the detection signal was generated by said transmission circuit.