Security system

• US 6,838,974 B2
• Filed: 12/27/2000
• Issued: 01/04/2005
• Est. Priority Date: 12/28/1999
• Status: Expired due to Fees

• Current Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Tsuzuki, Kazuhisa, Toyoda, Tooru, Misawa, Motohiro
• Primary Examiner(s): Horabik, Michael
• Assistant Examiner(s): BROWN, VERNAL U
• Application Number:
  US09/748,162
• Publication Number:
  US 20010005169A1
• Time in Patent Office: 1,469 Days
• Field of Search: 340/5.5, 340/5.7, 340/5.8, 340/825.36, 340/286.02, 340/288, 340/506, 340/517, 340/522, 340/538, 340/3.1, 348/159
• US Class Current: 340/5.5
• CPC Class Codes: G08B 13/19656 Network used to communicate with a camera, e.g. WAN, LAN, Internet
• CPC Class Codes: H04L 12/413 with random access, e.g. carrier-sense multiple-access with collision detection [CSMA-CD]
• CPC Class Codes: H04L 43/00 Arrangements for monitoring or testing data switching networks
• CPC Class Codes: H04N 5/76 Television signal recording

Abstract

Plural security units are coupled to plural control units through a communication line including transmission and response lines. Each control unit detects data collision on the transmission line to avoid the data collision. Re-transmission interval is independently assigned to each control unit. If the command to or from a security unit in charge of this control unit is received, the control unit rewrites the conditional data of the security unit in accordance with the detected command. The control (security) unit further includes a transmission (response) line monitoring portion, so that bi-directional communication is provided in addition of the response (transmission) line monitoring portion. Address data is classified to provide all unit communication, a group communication, and independent communications.

Claims

1. A security system comprising:

a plurality of security units; and

a plurality of control units connected to said plurality of security units through a communication line including a transmission line;

each of control units including;

information transmitting means for transmitting a command including control data and address data to at least one of said security units through said transmission line in response to a transmission request;

data collision detection means for detecting data collision on said transmission line, wherein said information transmitting means postpones transmission of said command when said collision detection means detects data collision on said transmission line;

re-transmission interval setting means for setting a different interval for each of said control units; and

information transmitting means for re-transmitting said command after the elapse of said different interval set by said retransmission interval setting means from the detection of said data collision.

2. The security system according to claim 1, wherein each of said control units further includes transmission line monitoring means for detecting said command transmitted from one of said control units and condition control means for storing condition data of said security units, wherein when said command detected by said transmission line monitoring means is directed to one of said security units in charge of said each control unit, said condition control means rewrites said condition data of said one security unit to equalize said condition data of said one security unit to a condition of said one security unit in accordance with said command by said transmission line monitoring means.

3. The security system according to claim 1, wherein said communication line further includes a response line so that each of said security units transmits a command through said response line of said communication line, and each of said control units further includes response line monitoring means for detecting said command on said response line transmitted from one of said security units and condition control means for storing condition data of said one security unit in charge of said each control unit, wherein said command detected by said response line monitoring means is from said one security unit in charge of said each control unit, said condition control means rewrites said condition data of said one security unit in accordance with said command detected by said response line monitoring means to equalize said condition data of said one security unit to a condition of said one security unit.

4. The security system according to claim 1, wherein each of said control units further includes transmission line monitoring means for detecting said command transmitted from one of said control units other than said each control unit, and said transmission line monitoring means receives said command when said command is directed to said each control unit to make bidirectional communications among said plurality of control units through said transmission line.

5. The security system according to claim 1, wherein said communication line further includes a response line so that each of said security units transmits a command through said response line of said communication line, and each of said security units includes response line monitoring means for detecting said command transmitted from one of said security units, said response line monitoring means receives said command when said command is directed to said each security unit to make bi-directional communications among said plurality of security units through said response line.

6. The security system according to claim 5, wherein each of said control units and each of said security units are made to control address data to be added to said commands so that each of said control units controls all said security units simultaneously while each of said security units controls all said control units simultaneously.

7. The security system according to claim 6, wherein each of said control units and each of said security units further include address data classifying means for classifying said address data so that each of said control units controls said security units simultaneously in unit of group while each of said security units controls said control units simultaneously in unit of group.