Fire alarm system

• US 5,650,762 A
• Filed: 03/23/1995
• Issued: 07/22/1997
• Est. Priority Date: 03/29/1994
• Status: Expired due to Fees

• Current Assignee: Nohmi Bosai Limited (Secom Company Limited)
• Original Assignee: Nohmi Bosai Limited (Secom Company Limited)
• Inventors: Takahashi, Kaoru, Usami, Yukihiko
• Primary Examiner(s): Hofsass, Jeffery
• Assistant Examiner(s): Lefkowitz, Edward
• Application Number:
  US08/409,154
• Time in Patent Office: 852 Days
• Field of Search: 340/505, 340/506, 340/508, 340/511, 340/512, 340/513, 340/514, 340/588, 340/589, 340/825.06, 340/286.05
• US Class Current: 340/286.05
• CPC Class Codes: G08B 17/00 Fire alarms; Alarms responsive to explosion

Abstract

A transmitter for use with a fire alarm system controls the monitoring of devices to be controlled based on a control command transmitted from a receiving section such as a fire receiver. With this transmitter, even if there is a short circuit in control lines for connecting the transmitter and the devices, it is not necessary to exchange fuses, and it is also possible to avoid the waste of power consumption which would otherwise incur during the actuation operation of the device(s). When the short circuit is recovered, the transmitter is able to correctly actuate the device(s). A small reverse current is permitted to flow in the control lines so as to enable the monitoring of a short circuit in the control lines by the transmitter. When the transmitter receives an actuation command from the receiving section, and if a short circuit in the control lines is detected, the transmitter goes into a standby state in which it holds an actuation signal for actuating the device(s) from being output to an actuating section. When the short circuit is recovered, the transmitter outputs the actuation signal to the actuating section.

Claims

1. A fire alarm system including a receiving section and a transmitter connected to said receiving section for controlling the monitoring of terminal devices based on a control command transmitted from said receiving section, said receiving section comprising:

a transmitting/receiving portion connected to said terminal devices for transmitting an actuation command to actuate at least one of said terminal devices and a status information return command to urge at least one of said terminal devices to return status information, and for receiving the status information returned from at least one of said terminal devices;

first indication means connected to said transmitting/receiving portion for indicating that the actuation command is being transmitted from said transmitting/receiving portion; and

second indication means connected to said transmitting/receiving portion for indicating that at least one of said terminal devices is being actuated in response to the actuation command, said transmitter comprising;

a transmitting/receiving circuit connected to said receiving section for transmitting/receiving the control command to and from said receiving section;

an actuating section connected to said transmitting/receiving circuit for actuating at least one of said terminal devices based on the actuation command transmitted from said receiving section; and

at least one of a first monitoring section and a second monitoring section respectively connected to said actuating section, said first monitoring section allowing a small reverse current to flow in control lines connected to said terminal devices so as to monitor a short circuit in said control lines, said second monitoring section monitoring a wire break in power lines which receive power from said receiving section.

5. A transmitter for use with a fire alarm system according claim 1, wherein said transmitter outputs an actuation signal to said actuating section for actuating at least one of said terminal devices when a wire break in said control lines is recovered.

2. A transmitter for use with a fire alarm system, for controlling the monitoring of terminal devices based on a control command transmitted from a receiving section, said transmitter comprising:

a transmitting/receiving circuit connected to said receiving section through signal lines for transmitting/receiving the control command to and from said receiving section;

an actuating section connected to said transmitting/receiving circuit for actuating at least one of said terminal devices based on an actuation command for actuating at least one of said terminal devices received from said receiving section; and

a monitoring section connected to said actuating section for permitting a small reverse current to flow in control lines connected to said terminal devices so as to monitor a short circuit in said control lines,

wherein said transmitter goes into a standby state in which it holds an actuation signal for actuating at least one of said terminal devices from being output to said actuating section when said transmitting/receiving circuit receives the actuation command from said receiving section and if a short circuit in said control lines is detected, and said transmitter outputs the actuation signal to said actuating section when the short circuit in said control lines is recovered.

6. A transmitter for use with a fire alarm system according to claim 2, wherein said transmitter outputs the actuation signal to said actuating section when a wire break in said control lines is recovered.

3. A transmitter for use with a fire alarm system, for controlling the monitoring of terminal devices based on a control command transmitted from a receiving section, said transmitter comprising:

a transmitting/receiving circuit connected to said receiving section through signal lines for transmitting/receiving the control command to and from said receiving section;

an actuating section connected to said transmitting/receiving circuit for actuating at least one of said terminal devices based on an actuation command for actuating at least one of said terminal devices received from said receiving section; and

a monitoring section connected to said actuating section for monitoring a wire break in power lines which receive power from said receiving section,

wherein said transmitter goes into a standby state in which it holds an actuation signal for actuating at least one of said terminal devices from being output to said actuating section when said transmitting/receiving circuit receives the actuation command from said receiving section and if a wire break in said power lines is detected, and said transmitter outputs the actuation signal to said actuating section when the wire break in said power lines is recovered.

7. A transmitter for use with a fire alarm system according to claim 3, wherein said transmitter outputs the actuation signal to said actuating section when a wire break in said control lines is recovered.

4. A transmitter for use with a fire alarm system, for controlling the monitoring of terminal devices based on a control command from a receiving section, said transmitter comprising:

a transmitting/receiving circuit connected to said receiving section through signal lines for transmitting/receiving the control command to and from said receiving section;

an actuating section connected to said transmitting/receiving circuit for actuating at least one of said terminal devices based on an actuation command for actuating at least one of said terminal devices received from said receiving section;

a first monitoring section connected to said actuating section for permitting a small reverse current to flow in control lines connected to said terminal devices so as to monitor a short circuit in said control lines; and

a second monitoring section connected to said actuating section for monitoring a wire break in power lines which receive power from said receiving section,

wherein said transmitter goes into a standby state in which it holds an actuation signal for actuating at least one of said terminal devices from being output to said actuating section when said transmitting/receiving circuit receives the actuation command from said receiving section and if a short circuit in said control lines is detected, and said transmitter outputs the actuation signal to said actuating section when the short circuit in said control lines is recovered, and

wherein said transmitter goes into a standby state in which it holds the actuation signal for actuating at least one of said terminal devices from being output to said actuating section when said transmitting/receiving circuit receives the actuation command from said receiving section and if a wire break in said power lines is detected, and said transmitter outputs the actuation signal to said actuating section when the wire break in said power lines is recovered.

8. A transmitter for use with a fire alarm system according to claim 4, wherein said transmitter outputs the actuation signal to said actuating section when a wire break in said control lines is recovered.