AU1497101A - Fire alarm system - Google Patents

Description

P/00/011 28/5/91 Regulation 3.2

AUSTRALIA

Patents Act 1990

ORIGINAL

COMPLETE SPECIFICATION STANDARD PATENT Name of Applicant: Actual Inventors Address for service is: Ampac Technologies Pty Ltd Gregory James McCulloch and Scott Richard Power WRAY ASSOCIATES 239 Adelaide Terrace Perth, WA 6000 Attorney code: WR Invention Title: Fire Alarm System Details of Associated Provisional Application No(s): PQ5088 filed 14 January 2000 The following statement is a full description of this invention, including the best method of performing it known to me:- -2- "Fire Alarm System" Field of the Invention This invention relates to the field of fire alarms, and in particular to a fire alarm for installation in a multiple occupancy building.

Background Art Fire alarm systems comprising a main control panel (or fire indicator panel) and fire detectors (either heat or products of combustion (smoke)) are quite widely employed, many being remotely monitored to enable despatch of fire brigade services. A difficulty experienced with modern smoke detectors is that they are very sensitive, and prone to false triggering. In a situation where the smoke detector is not remotely monitored, such as in stand-alone domestic applications (where the smoke detector serves as a warning device to occupants), such false Sotriggering (often caused by routine domestic activities such as cooking) does not usually cause any difficulty and is considered a mere annoyance. However, in a monitored alarm, particularly one installed in a multiple occupancy building, such false triggering can cause inconvenience and unwanted expense.

It is an object of this invention to provide a fire alarm system that obviates the aforementioned problems.

Throughout the specification, unless the context requires otherwise, the word "comprise" or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers.

Disclosure of the Invention In accordance with the invention there is provided a fire alarm system comprising control means, at least one fire detection means coupled to the control means; and an alarm acknowledgement means coupled to the at least -3one fire detector means and the control means, the fire detector means being operable to transmit an alarm state signal to the control means and the alarm acknowledgement means upon detection of products of combustion, the alarm acknowledgment means further including switch means coupled thereto for actuation after an alarm state signal has been transmitted from the fire detector means; the fire alarm system further including a first timer means operable to time out a first predetermined time period after an alarm state signal has been transmitted from the at least one fire detector means, such that, if the switch is not actuated within the first predetermined time period, the control means is operable to announce an alarm condition, and a second timer means operable, in response to the switch means being actuated during the first predetermined time period, to time out a second predetermined time, such that, within the second predetermined time the fire alarm system may be reset to a normal/standby condition, and, at the end of the second predetermined time, if the fire alarm system has not been reset to the normal/ standby condition, the control means is operable to announce the alarm condition.

By having the timeout periods, this provides an extended period of time within which the alarm state may be investigated before the alarm state is cancelled.

This can allow personnel to clear smoke from a smoke detector, thus resulting in resetting of the fire alarm system to a normal/standby condition.

This removes or lessens the number of times that, for example, the fire brigade is called out for false alarms. Alternatively, the alarm state may be cancelled at the fire indicator panel, if personnel deem such an action appropriate.

Preferably, the switch means may be a manually operable switch provided on the alarm acknowledgement means.

Preferably, the alarm acknowledgment means includes an alarm means operable to provide an alarm signal when the first timer means begins timing the first predetermined time period, the alarm signal being stopped in -4response to actuation of the switch means. The alarm means may be an audible buzzer.

Preferably, the alarm system further includes third timer means operable to time out a third predetermined time period, the third predetermined time period being equal to the sum of the first and second predetermined time periods, or slightly greater, such that, if the fire alarm system has not been reset to the normal/ standby condition, the control means is operable to announce the alarm condition after expiration of the third predetermined time period. This provides a failsafe operation, for example, if the wiring becomes burnt during a fire.

Preferably, the fire alarm system includes a plurality of fire detecting means, and an associated plurality of alarm acknowledgment means.

Preferably, the announcing of an alarm condition may comprise one or more of the issuing of a high audio level evacuate warning signal, actuation of 15 warning lights, actuation of emergency lighting, over-riding of elevators and/or air conditioning and ventilation systems, and summoning of the fire brigade.

o*•o Preferably, the fire detecting means is coupled to the control means by first circuit means, and the alarm acknowledgement means is coupled to the control means by second circuit means.

Preferably, the second circuit means is interfaced to the control means by an *interface means.

Preferably, the first and second timer means are provided in the alarm acknowledgement means.

The alarm system may include other preferred features not discussed above as will be apparent from the following description.

Brief Description of the Drawings A preferred embodiment of the invention will now be described in the following description, made with reference to the drawings, in which: Figure 1 is a schematic of a fire alarm system according to the embodiment; Figure 2 is a flowchart part of the software operation of a fire indicator panel according to the embodiment; and Figure 3 is a flowchart part of the software operation of an alarm acknowledgment module according to the embodiment.

Best Mode(s) for Carrying Out the Invention Throughout the specification, unless the context requires otherwise, the word "comprise" or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated integer or group of integers but not the i exclusion of any other integer or group of integers.

0 15 Referring to figure 1, the fire alarm system is shown in schematic form. The fire alarm system has a main control panel or fire indicator panel 11. The fire indicator panel 11 contains control circuitry that monitors fire detectors such as heat detectors or smoke detectors 13 as used in the embodiment. The smoke detectors 13 are connected to the fire indicator panel via a first circuit 15 using XP95 Loop protocol, whereby an alarm state can be signalled to the fire indicator ao. panel 11 via the first circuit from one or more of the fire detectors, when triggered.

The fire indicator panel 11 has a power supply (not shown), which includes a battery back up in the event of mains power supply failure. The control circuitry in the fire indicator panel 11 also controls an indicator status display (not shown), which displays the fire alarm system status (OK, Fire, Test etc), and may display the zone where a detector has been triggered. The control circuitry in the fire indicator panel 11 may control communications circuitry (not shown) contained within the fire indicator panel or externally thereof for external communication for alarm monitoring purposes. The control circuitry in the fire indicator panel 11 also contains circuitry (not shown) to transmit a fire status condition to the fire brigade, in order to summon fire fighters.

The aforementioned features of the fire indicator panel 11 are not exhaustive, the control circuitry in the fire indicator panel 11 also interfacing to sounders such as evacuation sirens, emergency lighting, and other features hitherto discussed.

Control switches can also be included for fire drill purposes and the like.

Each smoke detector 13 has an indicator lamp 17 to provide visual indication that the smoke detector 13 in question has sensed products of combustion (e.g.

smoke) and has been triggered. Each smoke detector 13 has a remote output 19 through which each smoke detector is interfaced to an alarm acknowledgement module 21. The alarm acknowledgement module 21 receives an alarm state signal from its associated smoke detector 13 through the remote output 19, when the smoke detector 13 in question has sensed products of 15 combustion and has been triggered.

o* Each alarm acknowledgement module 21 includes an audible buzzer 23 to provide audible indication that the associated smoke detector 13 in question has sensed products of combustion smoke) and has been triggered. Each alarm acknowledgement module 21 also includes a manually operable switch in the form of a single pole push-to-make switch 25 for a room occupant to push to acknowledge that indication has been given that the smoke detector 13 in o question has been triggered, and that the triggering warrants investigation. The switch 25 would not be pushed if there were a fire, since presumably the room occupant would be in the process of evacuating, or attempting to bring the fire 25 under control. The switch 25 should be clearly labelled with instructions, or room occupants should be clearly instructed as to the use of the switch 25 being to query if the status of an alarm state might be false.

The alarm acknowledgement modules 21 are connected via a second circuit 27 to an interface unit 29, which interfaces into the first circuit 15 (and is -7compliant in order to do so). The interface unit 29 provides a common secondary file signal to the fir indicator panel 11.

Circuitry in each alarm acknowledgement module 21, and the fire indicator panel 11 is microprocessor based, although in an alternative embodiment there is no reason why the fire alarm system could not be implemented in purely hardware form. The software for each alarm acknowledgement module 21 and the fire indicator panel is best described with reference to the flowcharts illustrated in figures 2 and 3. The normal state, where the alarm acknowledgement module 21 and the fire indicator panel 11 respectively are monitoring for a fire condition is indicated at 31 and 33 respectively. Referring to figure 2, circuitry in the fire indicator panel 11 continually monitors the first circuit 15 to determine if any smoke detector 13 (or other type of fire detector) has triggered (indicated at If a smoke detector 13 triggers, the circuitry in the fire indicator panel 11 turns on the indicator lamp 17 locally to the smoke detector 13, turns on the remote output 19, and starts a fail-safe timer (all indicated at 37) which times out a third predetermined period.

e* *.oo 0:0 Referring to figure 3, each alarm acknowledgement module 21 continually :monitors the remote output 19 of its associated smoke detector 13 (indicated at 39). If the remote output 19 of a smoke detector 13 is switched on, the alarm 20 acknowledgement module 21 switches on the associated audible buzzer 23 and starts a first timer (all indicated at 41). The first timer times out a first predetermined period (which can be any desired time sufficient to enable a person in proximity to act if necessary 30 seconds should prove sufficient) (see 43). If the first predetermined period times out with no action occurring, an "on" 25 signal is provided to the second circuit 27 (indicated at 45). If the switch 25 is pressed before the first predetermined period times out, the associated audible buzzer 23 is turned off, and a second timer is started (indicated at 47).

The second timer times out a second predetermined period (indicated at 49), which is intended to provide enough time to clear the smoke from the smoke detector, which will cancel the issuance of the detected alarm state at the fire indicator panel 11, if the alarm state triggered by the smoke detector is a false alarm. If the second predetermined period times out with no action occurring, an "on" signal is provided to the second circuit 27 (indicated at 51). However, if the alarm state is cancelled due to smoke being cleared from the smoke detector within the second predetermined period, the circuitry of the fire indicator panel 11 resumes normal/standby state shown at 33.

In all cases, should the remote output 19 be switched off (which occurs by resetting the fire indicator panel 11), the alarm acknowledgement module 21 will cancel the "on signal" in the second circuit 27 (if already activated) and reset the alarm acknowledgement module 21 to normal state shown at 31.

Referring back to figure 2, the circuitry of the fire indicator panel 11 monitors whether the smoke detector 13 remains triggered (indicated at 53). If not, the fire indicator panel 11 resumes normal state (shown at 33). If the smoke detector 13 remains triggered, the circuitry of the fire indicator panel 11 checks if an "on" S 15 signal is present in the second circuit 27 (indicated at 55). On issuance of an "on" signal in the second circuit 27, or if a third predetermined period timed by the fail-safe timer expires (indicated at 57), the circuitry in the fire indicator panel 11 causes the fire alarm system to go into "alarm" condition, whereby inter-alia an alarm is sounded, and the fire brigade is summoned. The third predetermined 20 period should be a period that is the sum of the first and second predetermined periods or slightly greater. The provision of the fail-safe timer ensures that the fire brigade will be summoned in the event that a fire destroys part of the wiring to the fire indicator panel, or any alarm acknowledgement module 21.

The fire alarm system according to the embodiment is intended to be used in any 25 multiple occupancy building such as a hostel, hotel, or barracks. A smoke detector 13 and an alarm acknowledgment module 21, and their associated switch 25, buzzer 23, and indicator lamp 17 are placed in each room, while a single (usually) fire indicator panel monitors the system. In the advent of a false alarm (caused by burning toast for example), the simple procedure provided by the system of the invention will avoid the expense and inconvenience of the fire -9brigade being summoned. In the event that the building is unoccupied, the maximum delay before the fire brigade will be summoned through actuation of an alarm state at the fire indicator panel will be the first predetermined time.

It should be appreciated that the scope of the invention is not limited to the particular embodiment described herein. For example, a fire indicator panel may support multiple first and second circuit installations. The fire detector employed need not necessarily be a smoke detector, since heat sensors such as bimetallic resettable temperature switches may be employed alternatively or additionally.

Furthermore, non-resettable low temperature eutectic metal heat sensors, and indeed manual call points also may be employed in addition to the smoke detectors and/or resettable temperature switches. The protocol for connecting detectors need not be XP95, but may be any other protocol, such as for example, Hochiki protocol, or Ziton protocol.

.e *eeo *et

Claims (11)

1. A fire alarm system comprising: control means; at least one fire detection means coupled to the control means; and an alarm acknowledgement means coupled to the at least one fire detector means and the control means, the fire detector means being operable to transmit an alarm state signal to the control means and the alarm acknowledgement means upon detection of products of combustion, the alarm acknowledgment means further including switch means coupled thereto for actuation after an alarm state signal has been transmitted from the fire detector means; the fire alarm system further including: a first timer means operable to time out a first predetermined time period after o an alarm state signal has been transmitted from the at least one fire detector means, such that, if the switch is not actuated within the first predetermined time period, the control means is operable to announce an alarm condition; and a second timer means operable, in response to the switch means being actuated during the first predetermined time period, to time out a second 20 predetermined time, such that, within the second predetermined time the fire alarm system may be reset to a normal/standby condition, and, at the end of the second predetermined time, if the fire alarm system has not been reset to the normal/ standby condition, the control means is operable to announce the alarm condition. -11

2. A fire alarm according to claim 1, wherein the switch means is a manually operable switch provided on the alarm acknowledgement means.

3. A fire alarm system according to claim 1 or claim 2, wherein the alarm acknowledgment means includes an alarm means operable to provide an alarm signal when the first timer means begins timing the first predetermined time period, the alarm signal being stopped in response to actuation of the switch means

4. A fire alarm system according to claim 3, wherein the alarm means is an audible buzzer.

A fire alarm according to any of the preceding claims, further including third timer means operable to time out a third predetermined time period, the third predetermined time period being equal to the sum of the first and second predetermined time periods, or slightly greater, 15 such that, if the fire alarm system has not been reset to the normal/ .o *standby condition, the control means is operable to announce the alarm condition after expiration of the third predetermined time period.

6. A fire alarm system according to any of the preceding claims, including a plurality of fire detecting means, and an associated plurality of alarm acknowledgment means.

7. A fire alarm system according to any preceding claim, wherein the announcing of an alarm condition comprises one or more of the issuing of a high audio level evacuate warning signal, actuation of warning lights, actuation of emergency lighting, over-riding of elevators and/or air conditioning and ventilation systems, and summoning of the fire brigade.

8. A fire alarm system according to any preceding claim, wherein the fire detecting means is coupled to the control means by first circuit means, -12- and the alarm acknowledgement means is coupled to the control means by second circuit means.

9. A fire alarm system according to claim 9, wherein the second circuit means is interfaced to the control means by an interface means.

10. A fire alarm system according to any of the preceding claims, wherein the first and second timer means are provided in the alarm acknowledgement means.

11. A fire alarm system as hereinbefore described, with reference to the accompanying drawings. Dated this fifteenth day of January 2001 Ampac Technologies Pty Ltd Applicant Wray Associates Perth, Western Australia Patent Attorneys for the Applicant(s) 0. oooo• ooooo o *oo