GB2349726A

GB2349726A - Alarm apparatus

Info

Publication number: GB2349726A
Application number: GB0010098A
Authority: GB
Inventors: Nicholas Mark Sims
Original assignee: GARDINER TECHNOLOGY Ltd
Current assignee: GARDINER TECHNOLOGY Ltd
Priority date: 1999-05-07
Filing date: 2000-04-25
Publication date: 2000-11-08
Anticipated expiration: 2020-04-25
Also published as: GB0010098D0; GB9910700D0; GB2349726B

Abstract

An alarm apparatus includes control means 20, an alarm indication means 24 remote from the control means with a connection 26, 28 therebetween and means for monitoring the current delivered to or consumed by selected component(s) in or associated with the alarm indication means. This provides the benefit that only one measurement point is required in order to measure a multitude of values e.g. LED current, battery charge current, quiescent current of the bell box circuit, strobe current, sounder current etc. By working out when to sample e.g. the strobe current and sounder current, it is possible to determine whether e.g. the driver circuit is working correctly and also whether the last component in the line is working correctly (e.g. a strobe tube or piezo sounder).

Description

Alarm apparatus The present invention relates to alarm apparatus and in particular to improvements in information communication in the apparatus e. g. between a bell box and a control panel of the alarm apparatus.

An alarm (which may be an intruder alarm, fire alarm or other) usually includes, at least in part, a control panel connected to one or more bell boxes.

When the control panel is alerted to an alarm condition e. g. an intruder, via various sensors, the bell box (es) are activated. A bell box usually consists of a sound emitting device (referred to here as a"sounder") and /or a light emitting device (referred to here as a "strobe"). Figure 1 shows a schematic layout of a traditionally wired bell box. Additional features in a bell box may include a back up battery, tamper switches, a bell ring timer and some form of display (typically LED).

Figure 1 is a schematic layout of a traditionally wired alarm system including a bell box 2. Most bell boxes have a backup battery 4 but this is not essential. The purpose of the backup battery is to sound the bell if the main power supply wires to the bell box are cut.

Sounders are classified in. two types: Self Activating Bell (SAB) and Self Contained Bell (SCB).

An SAB will always try to ring power the sounder from the external power source, i. e. from the control panel.

It will only use its backup battery if the external power is lost (for example if the wires 6 are cut). In SCB mode the sounder will always operate from its own backup battery. In this case the only purpose of the external power source is to charge the backup battery.

In most intruder alarm systems known in the art, the trigger mechanism to activate the bell or sounder is referred to as"negative trigger". The control panel holds the trigger wire (8,10) at a potential usually close to a 12 V power supply. In the event of the panel needing to trigger the sounder, this potential is removed and switched to 0 V. Similarly, if this wire is cut, the potential will be removed and the sounder will operate. In some older designs the trigger system worked in the reverse sense to above and was known as positive trigger.

The strobe trigger mechanism 10 works in a separate manner to the bell trigger 8. In some bell boxes in the art the strobe and bell circuitry have completely isolated supplies. If this is the case the trigger supplies the 0 V supply to the strobe circuit, and all the current flows down the"trigger"wire. In circuits where the strobe and bell run off a common supply, then this is more normally a low current trigger.

The bell box will usually contain one or more LEDs. These are illuminated or flash when the power is supplied to the bell box. However, they are given the ability to flash in a variety of patterns dependent upon the status of the bell box, for example whether the tamper switches are open or closed, or whether the back up battery is functional or not. The state of the tamper switches (i. e. open or closed) is transmitted to the control panel 12 via a tamper return signal wire 14.

Most bell boxes in the art have one or more timers inside. These will limit the time the sounder can operate regardless of the length of time the trigger signal is present from the control panel. A typical time limit would be 18 mins, but some bell boxes have a number of selectable time options. These time options vary from 5 seconds up to 20 minutes. A range of bell boxes have been developed previously where the timer will be set to 5 seconds when the unit is first powered, then switching to 18 minutes (for example) once all the tamper switches have been closed. This is to assist the installer on initial commissioning of the bell box. Also known in the art is the ability to set the timers in a bell box by activating the strobe trigger a number of times.

A further wire may be connected from the control panel to the bell box. Once again this has two states, 0 V or 12 V. It changes state when the control panel is set (and back again when the control panel is unset). Its purpose is to force the sounder to either beep, or flash the strobe one or more times, when the panel sets, so the user outside the premises knows that his system is armed.

One of the major drawbacks with traditionally wired bell boxes is that it is not possible to know the state of the back up battery located within the bell box. The only way an installer can determine the exact state is to measure the battery terminal voltage by accessing the battery itself inside the bell box. This can be a laborious task and one to be avoided where possible.

The installer may check whether the battery is functional or not from the control panel simply by removing the power feed to the bell box and checking that the unit sounds. However, this does not inform him as to the real state of the bell box back up battery. Additionally, it is not possible for this information to be provided to someone performing a system measurement from a remote location (e. g. away from the alarmed premises, for example at a monitoring centre).

There are bell box designs in the art which have circuitry to monitor the existence of a backup battery.

Again, this monitor system can only determine whether the battery is functional or not and this result is displayed on the box (e. g. via a LED display). This once again requires the installer to be on site and does not give a qualitative result. In addition, the result is displayed whether requested or not. In other words an intruder may also determine that the backup battery has failed.

One difficulty in providing any additional information concerning the bell box at the control panel is the primitive nature of the interconnection between the control equipment and the external bell box. It is traditionally a five, six or even seven wire connection, which incorporates a number of power wires, and a number of inputs and outputs that are either on or off.

The present invention aims to mitigate at least some of these problems In a broad sense, the present invention provides an"intelligent"means of connection, thus improving security since interference with the signals may be more difficult. Also, diagnostic data may then be provided at the control panel from the bell box. This could be accessed by the installer on site, thus removing the requirement for a trip to the bell box, or by an installer remote from the site communicating with the panel via a modem link.

Accordingly, in a first aspect, the present invention provides an alarm apparatus including control means, an alarm indication means remote from the control means with a connection therebetween and signal means for monitoring the current consumed by selected component (s) in or associated with the alarm indication means. Such means may be located in or associated with the control means and may be operable continuously or alternatively may be operable at selected times within the operational cycle of the alarm apparatus.

This provides the benefit that only one measurement point is required in order to measure a multitude of values e. g. LED current, battery charge current, quiescent current of the bell box circuit, strobe current, sounder current etc. By working out when to sample the strobe current and sounder current (for example), it is possible to determine whether the driver circuit (for example) is working correctly and also whether the last component in the line is working correctly (e. g. a strobe tube or piezo sounder).

The current measurement means may include means for comparing the measured current values with predetermined expected current values in order to assess whether or not the selected components are functioning correctly.

Additionally or alternatively, the monitoring means may monitor the output current from the control means.

In a further aspect, the invention may include means for varying the driving voltage wave form which is supplied to selected components. For example, the driving voltage wave form to a piezo sounder or other sounder or strobe device can be varied in order to test the device without causing the sounder to ring. In this particular example, the wave form supplied to the sounder is such that the sounder is operated at a frequency outside the range of human hearing (for example above 20kHz) so that the current to the sounder can be measured in accordance with the above aspect of the invention and the operation of the sounder and sounder circuitry tested.

The apparatus may also include connection means for transferring information along the connection, the signal means being adapted to transfer information relating to more than one function of the alarm indication means, wherein the information relating to each separate function is transferred sequentially.

The alarm indication means may, for example, be a bell box or sounder. The bell box or sounder may be positioned externally or internally of an alarmed premises, for example, attached to an internal or external wall of a building.

The connection means between the control means and e. g. a bell box may thus carry information relating to multiple functions of the bell box. This may be termed a"serial link", which is used in the following text.

The serial link may carry information in the form of signals transferred sequentially, for example, electrical signals, optical signals, etc.

As an example, the voltage across a back up battery located in the bell box will be used here as the information of interest. The voltage across the back up battery might be measured by circuitry known in the art located within the bell box. This information may then be passed down the"serial link"to e. g. a control panel. Alternatively, connections across terminals of the back up battery in the bell box may allow the voltage across the battery to be measured at the control panel via a connection between the control panel and the bell box.

The alarm apparatus may, for example, be a security/intruder (burglar) alarm, fire alarm or indeed any other type of alarm system. The alarm indication means will usually include several elements such as a sounder and/or strobe and/or backup battery located inside e. g. a"bell box". The signal means may be simply some kind of electrical connections between one or more items of the alarm indication means and the connection, which could for example be an electrical or optical cable. Additionally or alternatively, the signal means may be more complicated and could include some signal processing equipment to gather and process the information before it is transmitted. Additionally or alternatively, signal means may be present at the same location as the control means rather than in the alarm indication means, for example, within a control panel.

Preferably the alarm indication means includes, a backup battery and the signal means is adapted to transfer information relating to the voltage across the backup battery. In this way the status or condition of the backup battery may be monitored. Furthermore, the signal means may be adapted to transfer information relating to the battery charge current and/or an external power supply voltage.

Furthermore, in preferred embodiments the signal means may be adapted to transfer information relating to any or all of the following: the electrical resistance of individual tamper switches ; the current consumption by the alarm indication means during quiescent operation; the current consumption of a sounder (whether in operation or not); the current consumption of a strobe (whether in operation or not); the brightness of the strobe (e. g. by including some light measuring equipment such as a photodiode adjacent the strobe); the output of the sounder; the tone of the sounder; suppression of the operation of the sounder; the mode of setting confirmation to be used by the alarm indication means; display data shown on the alarm indication means (which may include one or more LED's).

The standard features found on the existing method of wiring bell boxes may be provided for in this improved system. However, the switch activation may now converted to a message sent along the serial link.

For example, messages which might be sent include "trigger sounder","trigger strobe"and"send status of tamper switches".

The signal means may also or alternatively be adapted to transfer information relating to the terminal voltage of a backup battery for the alarm indication means, such as a value of the terminal voltage.

In a second aspect, the present invention provides a method of transferring information between an alarm indication means and a control means of an alarm apparatus, the method including the step of monitoring current drawn by the alarm indication means.

An embodiment of the present invention will now be described with reference to the accompanying drawings in which: Figure 1 shows a schematic diagram of a typical alarm apparatus known in the art.

Figure 2 shows a schematic diagram of an embodiment of the present invention.

Figure 2 includes a control panel 20 which supplies power via power supply wires 22 to a bell box 24. The control panel also is included in a communication link (in this case a serial communication link) with the bell box 24 via a serial transmitter 26 and serial receiver 28. There may also be one or more additional serial transmitters 30 which may go to a single bell box or may alternatively go to a plurality of bell boxes.

The bell box includes circuitry to monitor the power supply and alarm trigger lines. It also includes charging circuitry for the backup battery 32 which is usually located within the bell box housing. Finally, the bell box may include a bell ring timer and some form of display e. g. an LED display.

The control panel itself may be connected via a communications link 34, a modem 36, a communications line 38 (e. g. a telephony line), a further modem 40 and communications link 42 to a central monitoring station 44. The actual connection within the central monitoring station may be to an item of equipment such as a PC. In this way, the central monitoring station is able to access remotely any information which is available at the control panel 20.

As will be seen from figure 2, the serially connected bell box requires only a four wire connection, thereby reducing the usual number of wires in the installation whilst at the same time improving the amount and type of information which is providable between the bell box and the control panel.

As will be appreciated, information on many features may be sent via the"serial link"26,30.

Measurement of different quantities may be made using circuitry known in the art either in the bell box or at the control panel.

Some examples of information, any or all of which can be sent along the serial link, are as follows: 1. Measure battery voltage, either 1.1. On charge 1.2. Off charge 1.3. On or off charge but with a dummy load connected.

2. Measure battery charge current.

3. Measure external power supply voltage.

4. Measure resistance of tamper switches 4.1. Tamper switches can be read individually rather than connected together as one tamper signal.

5. Measure quiescent current consumption.

6. Measure sounder current consumption.

7. Measure strobe current consumption.

8. Measure strobe brightness.

9. Measure sounder output.

10. Provide a different sounder tone dependent upon what has caused the alarm. The panel, having determined the cause of the alarm, can tell the sounder to activate using one of a pre-programmed tone. For example one tone for an intrusion alarm, another for a fire alarm, one for a tamper, etc. The tone used may be derived from a signal sent to the bell box sounder via the serial link from the panel. This would allow for an unlimited number of tones as they could be programmed from a remote connection.

11. Suppress bell box tamper information from causing a local sound (for example when an installer is wiring up or checking the sounder).

12. Determine which mode of setting confirmation is to be used (for example, an audible blip, or a strobe flash, none or both). As the panel can choose it may use an audible blip if the system is fully set, and a strobe flash if the system is part set.

12.1. A light detector (known in the art) in the bell box could detect the ambient light level and decide that if it is dark the strobe will flash if the panel sets but that the sounder will blip if it is daylight. This decision could be made at the panel if the light detector information is passed down the serial link.

13. The actual pattern used to flash the indicator LEDs on the bell box could be provided by the control panel via the serial link.

Any or all of items 1, 2,4,5,6,7,8 and 9 in the above list can be used to gauge how the performance of the system is degrading over time. This information may be used to predict when an element of the bell box is likely to fail.

It is possible to determine whether a strobe is flashing or a sounder sounding (to a reasonable approximation) by measuring a voltage across the strobe tube or sounding device. This is currently done by a bell box in the art which then sets a fault output and/or flashes the LED's in a different sequence if the strobe or sounder are determined to be malfunctioning.

It is possible to accurately measure whether the sounder is sounding or the strobe flashing by monitoring the current consumption.

The bell box knows the exact supply voltage which is measured and reported to the control panel via the serial link. In contrast, bell boxes in the art are designed to work at an inexact voltage, typically over a range from 10 to 16 V. Therefore, in the invention described here, the sounder algorithm may be adjusted to optimise the sound output without excessive current consumption across the working voltage range. This allows for the maximum sounder level at any voltage without the risk of power dissipation damaging the unit. Similarly, the strobe output may be optimised for current consumption.

The bell box is arranged to perform sounder and strobe tests whenever the sounder or strobe are activated. This may be most frequently if a setting confirmation is selected. Alternatively, it is possible for the control panel to dictate that the bell box does a specific sounder test or strobe test. These may use different patterns to those used in alarm conditions.

Interrogation of the bell box can take place under control of either the control panel or e. g. a remote pc. The system allows a number of bell boxes (if more than one is required) to be connected together, and the protocol allows for individual addressing of these bell boxes. Further, it also allows for additional bell boxes to be connected using the advanced serial protocol but will not provide the means to read back diagnostic measurements from these additional bell boxes.

The control panel 20 includes current measurement means for monitoring the current supplied to the bell box via a power supply wires 22. The measurements take place at selected time intervals and the measured values are compared by the current measurement means or the control panel with predetermined current values which would be expected if the selected components are operating correctly. If the measured current is different to that which is expected (and the difference may include a predetermined margin for measurement error) then a suitable signal may be produced by the control panel in order to alert the user to a malfunction of one or more components. In this embodiment, any or all of the components of the communications link 26,28 and 30 may be omitted.

The above explanation is given by way of example only and modifications will be apparent to those skilled in the art.

Claims

CLAIMS: 1. An alarm apparatus including control means, an alarm indication means remote from the control means with a connection therebetween and means for monitoring the current delivered to or consumed by selected component (s) in or associated with the alarm indication means.
2. Apparatus according to claim 1 wherein the monitoring means are located in or associated with the control means.
3. Apparatus according to claim 1 or claim 2 wherein the monitoring means are operable continuously.
4. Apparatus according to claim 1 or claim 2 wherein the monitoring means are operable at selected times within the operational cycle of the alarm apparatus.
5. Apparatus according to any of the above claims wherein the current measurement means includes means for comparing the measured current values with predetermined expected current values.
6. Apparatus according to any of the above claims including means for varying the driving voltage wave form which is supplied to selected components.
7. Apparatus according to claim 6 wherein the wave form supplied to a sounder is such that the sounder is operated at a frequency above 20kHz.
8. Apparatus according to any preceding claim including signal means for transferring information along the connection, the signal means being adapted to transfer information relating to more than one function of the alarm indication means, wherein the information relating to each separate function is transferred sequentially.
9. The apparatus of claim 8 wherein the alarm indication means includes a back up battery and wherein the signal means is adapted to transfer information relating to the voltage across the back up battery.
10. The apparatus of claim 9 in which the signal means is adapted to transfer information relating to the battery charge current.
11. The apparatus of any of claims 8 to 10 in which the signal means is adapted to transfer information relating to an external power supply voltage.
12. The apparatus of any of claims 8 to 11 in which the signal means is adapted to transfer information relating to the electrical resistance of individual tamper switches.
13. The apparatus of any of claims 8 to 12 in which the signal means is adapted to transfer information relating to the current consumption by the alarm indication means during quiescent operation.
14. The apparatus of any of claims 8-13 in which the signal means is adapted to transfer information relating to the current consumption due to a sounder in the alarm indication means.
15. The apparatus of any of claims 8 to 14 in which the signal means is adapted to transfer information relating to the current consumption due to a strobe in the alarm indication means.
16. The apparatus of any of claims 8 to 15 in which the signal means is adapted to transfer information relating to the brightness of the strobe.
17. The apparatus of any of claims 8 to 16 in which the signal means is adapted to transfer information relating to the output of the sounder.
18. The apparatus of any of claims 8 to 17 in which the signal means is adapted to transfer information relating to the tone and/or frequency and/or sound pattern of the sounder.
19. The apparatus of any of claims 8 to 13 in which the signal means is adapted to transfer information relating to the suppression of operation of the sounder.
20. The apparatus of any of claims 8 to 19 in which the signal means is adapted to transfer information relating to a mode of setting confirmation to be used by the alarm indication means.
21. The apparatus of any of claims 8 to 20 in which the signal means is adapted to transfer information relating to a display shown on the alarm indication means.
22. The apparatus of any of claims 8 to 21 in which the display shown on the alarm indication means includes LEDs.
23. The apparatus of any of claims 8 to 22 in which quantitative measurement of the information of the above claims occurs within the alarm indication means.
24. The apparatus of any of claims 8 to 23 in which quantitative measurement of the information of the above claims occurs within the control means.
25. The apparatus of any of claims 8 to 24 in which the control means is connected to more than one alarm indication means.
26. The apparatus of any of claims 8 to 25 in which the control means monitors the status of devices within the alarm indication means.
27. The apparatus of any of claims 8 to 26 in which the control means displays the status of the devices within the alarm indication means.
28. The apparatus of any of claims 8 to 27 in which the control means may be operated from a remote location.