Extension speaker

Abstract

An extension speaker 2 for an intruder alarm system comprises a housing 4; a sound generating device (20,fig.3) positioned within the housing 4; and an illumination device 6 at least partially definin

Description

The present invention relates to an extension speaker for an alarm system and an alarm system comprising an extension speaker. Alarm systems are typically fitted within buildings to detect burglaries or intruders and to alert nearby persons or remote monitoring services when an intruder is present. Alarm systems typically comprise at least one sensing device connected to a control panel. The sensing device may be for example a passive infrared (PIR) sensor to detect the presence of a person, a magnetic catch to detect the opening of a door, or any other suitable sensing means. The control panel is typically configured to monitor the status of the sensing device and to raise an alarm in response to an unacceptable operating parameter (for example, when the PIR sensor detects the presence of an intruder when the alarm is armed). Most alarm systems for domestic dwellings comprise an external sounder, otherwise referred to as a bellbox, which is positioned on the outside of the property in a prominent place. When an unacceptable operating condition is recognised by the control panel, the control panel outputs a signal to the bellbox causing the bellbox to generate audio and visual alarms (e.g. by generating a loud noise and / or flashing a light such as a strobe light). Whilst such bellboxes are in electrical communication with the control panel, the bellboxes themselves comprise an independent power source and independent sound and light generating electronics so that if the connection between the control panel and the bellbox is cut (for example, deliberately by an intruder), the bellbox is still able to generate audio and visual alarms. Alarm systems typically comprise other accessories, for example a keypad and an extension speaker. For domestic dwellings, the keypad is typically positioned by an entrance door to the property, to allow the user to arm and disarm the alarm system when entering or leaving the property. Extension speakers are typically used in combination with keypads to provide an auditory indication of the current status of the alarm system. For example, when the alarm is first armed when the user is leaving the property, the extension speaker may emit a sound indicating that the alarm will be armed when the entrance door is next closed. Likewise, when the system is armed, the extension speaker may emit a sound when the entrance door is opened to indicate that the system is armed and must be disarmed within a certain period of time otherwise the alarm will be triggered. The sound may change with time as the period runs down to indicate to the user that the alarm is about to be triggered. This can be done for example, by increasing the volume, the tempo or the tone of the sound. Whilst extension speakers are a useful accessory in many properties, the beneficial effects of an extension speaker is reduced if the user is hard of hearing or deaf, or if the extension speaker is obstructed by an object such as an article of clothing (e.g. a coat, bog or the like). Furthermore, if the speaker itself is damaged, for example by water ingress, impact or the like, the extension speaker is no longer able to communicate effectively with the user. It is therefore an object of the invention to provide an extension speaker for an alarm system and an alarm system comprising an extension speaker that obviates or mitigates at one or more of the disadvantages of the prior art, whether identified herein or elsewhere. It is a further object of the invention to provide an improved or an alternative an extension speaker for an alarm system and an alarm system comprising an extension speaker. According to a first aspect of the invention, there is provided an extension speaker for an alarm system, comprising: a housing; a sound generating device positioned within the housing; and an illumination device at least partially defining an exterior of the housing and viewable by a user; wherein the sound generating device is configured to generate sound in response to a sound driving current output by the control panel and the illumination device is configured to display a lighting pattern in response to a illumination driving current output by the control panel. The term “extension speaker” is a term of the art which encompasses speaker accessories for an alarm system that are entirely driven by an output current from the control panel, and which are not equipped with an independent power supply, decisionmaking control electronics or signal amplification means. As compared to a bellbox, such extension speakers must be umbilically connected to the control panel in order to receive the necessary power required for them to function. By contrast, a bellbox has a separate power supply to the control panel, and has signal generating means and amplifiers configured to generate sound and / or light. In this context, the term “sound driving current” encompasses a current and / or signal that contains the waveform of the sound and the electrical power required to generate the sound using the sound generating device at a desired volume. Likewise, the term “illumination driving current” encompasses a current and / or signal that provides the electrical power required to illuminate the illumination device in one or more lighting patterns. A “lighting pattern” in the context of the present invention encompasses for example the brightness and / or colour of the light emitted by the illumination device, the position relative to the housing of the part of the illumination device that is activated to emit light (for example, lighting only a portion of the illumination device or all of the illumination device), a flashing rate of the illumination device or part of it, and generally any other physical, spatial or temporal property of the light emitted by the illumination device. Because the extension speaker comprises both a sound generating device and an illumination device that is viewable by the user and configured to display a lighting pattern, the extension speaker is able to communicate with the user using both light and sound. As such, the extension speaker of the present invention is easier to use and better able to communicate with the user, since it uses two of the user’s senses rather than one. Additionally, because the illumination device uses light and sound to communicate with the user, the extension speaker of the present invention is therefore suitable for use by users that are hard of hearing or deaf as well as by users that are partially sighted or blind. Furthermore, the use of both a sound generating device and an illumination device means that the extension speaker of the present invention is able to compensate for the failure of either the sound generating device or the illumination device and still communicate effectively with the user. Further still, the lighting pattern of the illumination device need not be solely configured to communicate information with the user, but may additionally or alternatively be configured to provide a source of illumination to light up an area of a building. For example, the illumination device could be configured to light up a porch in response to the control panel detecting that a door of the porch has been opened, indicating that the user is entering or leaving the building, or in response to a PIR sensor detecting that a person is approaching a door of the building (e.g. in the manner of a security light). The illumination device may therefore also provide an additional deterrent for intruders approaching the building and / or improved safety for users entering or leaving the building in darkness. The illumination device may be configured to display a plurality of lighting patterns, each lighting pattern corresponding to an operational state of the alarm system. When the illumination device is configured to display a plurality of lighting patterns, the illumination device may be used to communicate alarm status information with the user so that the user is able to quickly ascertain a current or historical operating state of the alarm system without reference to the control panel. This is particularly useful where the extension speaker is positioned at an entrance or exit to a building, as the status information can be easily determined upon entrance or exit. The illumination device may be configured to generate the plurality of lighting patterns in dependence upon a plurality of outputs of the control panel. That is to say, the control panel may have a plurality of outputs, each output controlling a different part of the illumination device (for example, each output controlling one or more illumination sources of the illumination device), and each output may be configurable to selectively illuminate the corresponding part of the illumination device. For example, one output may control red light and another output may control green light. Activating one or the other of the outputs will produce red or green light, whilst activating both of the outputs will produce yellow light. The emission of red, green, and yellow light corresponds to three different lighting patterns of the illumination device. The illumination device may comprise a first illumination source configured to emit coloured light at a first wavelength and a second illumination source configured to emit coloured light at a second wavelength different to the first wavelength. For example, the first illumination source may emit green light in the range of around 520 nm to around 560 nm and the second illumination source may emit red light in the range of around 635 nm to around 700 nm. Most users will have an intrinsic understanding of coloured illumination sources being used to convey positive, negative or neutral messages, such as for example in the manner of a traffic light. The use of coloured illumination sources therefore enables the alarm system to easily signal to the user that the alarm system is functioning normally, or if a fault is present and the severity of that fault. The first illumination source may be substantially collocated with the second illumination source. That is to say, the first and second illumination sources are positioned at approximately the same position within the illumination device. When the first illumination source and second illumination source are collocated and activated at the same time, superposition of the light emitted from both sources may cause a third wavelength of light to be produced by the illumination device. For example, when the first and second illumination sources correspond to green and red light, activating both illumination sources at the same time will produce yellow light. As such, two illumination sources can be used to create three or more colours of light. The first and second illumination sources may be embodied in a bicolour light source, such as a bicolour LED or the like. The illumination device may comprise a plurality of first illumination sources and a plurality of second illumination sources, each one of the first illumination sources being collocated with each one of the second illumination sources to define a pairing, and each pairing being spaced apart from one another. When the pairings are spaced apart from one another the user can use the relative positions of the illumination sources to distinguish between them. The illumination device may comprise a third illumination source configured to emit white light. White light may be used to illuminate a working area for the user. For example, the extension speaker may be located within a porch and the white light emitted by the illumination device can be used to illuminate the porch to aid the user when entering or leaving the building. The illumination device may comprise a plurality of third illumination sources spaced apart from one another. Each pairing of the first and second illumination sources and each one of the third illumination sources may be arranged in an alternating pattern. When the illumination sources are arranged in an alternating pattern, the distinction between the first and second sets of illumination sources is more obvious. The housing may comprise a cap, and wherein the illumination device may comprise a plurality of illumination sources arranged around the perimeter of the cap. The illumination sources may be the first illumination sources, second illumination sources or third illumination sources. When the illumination sources are arranged around the perimeter of the cap, the overall size of the illumination device is relatively large (being slightly larger than the cap) but the number of illumination sources required is relatively small compared to the number of illumination sources that would be required to illuminate the entire area of the cap. As such, the illumination device may produce a lighting pattern with a large area, enabling the extension speaker to better communicate with or illuminate the user using a relatively small number of illumination sources. The illumination device may comprise a light diffuser configured to diffuse light emitted by an illumination source. When a light diffuser is used, the light emitted from the illumination sources is scattered within the light diffuser before being re-emitted. The light is guided along the light diffuser and re-emitted over a much larger area than the area of the light source itself. As such, fewer, lower power or smaller light sources can be used whilst producing a sufficiently visible lighting pattern. The light diffuser may comprise a translucent light-scattering material. The extension speaker may comprise a tamper detection device configured to detect a tamper event. A “tamper event” encompasses an event in which an intruder attempts to disable the extension speaker by removing it from a wall or by opening the housing when the alarm system is armed. The housing may comprise a front portion and rear portion that are separable from one another. The tamper detection device may comprise a switch that is closed by coupling the front and rear portions of the housing to one another and opened by uncoupling the front and rear portions of the housing from one another. The rear portion of the housing may comprise a separable portion configured to separate from the rear portion of the housing in response to a tamper event. The switch may be configured to open in response to the separable portion being separated from the rear portion of the housing. According to a second aspect of the invention there is provided an alarm system comprising: an extension speaker according to the first aspect of the invention; and a control panel configured to output the sound driving current and / or illumination driving current in response to an operating condition of the control panel. A detailed description of the invention will now be provided with reference to the accompanying drawings, in which: Figure 1 is a plan view of an extension speaker in accordance with the present invention; Figure 2 is a perspective view of the extension speaker; Figure 3 is a cross-sectional view through line A-A of Figure 1; Figure 4 is a perspective view of a portion of an illumination device of the external speaker; Figure 5 is a reverse plan view of a front portion of a housing of the external speaker; Figure 6 is a reverse plan view of a rear portion of the housing of the external speaker; Figure 7 is a cross-sectional view through line B-B of Figure 1; and Figure 8 is an obverse plan view of the front portion of the housing of the external speaker. With reference to Figures 1 and 2, there is provided an extension speaker 2 for an alarm system. The extension speaker 2 comprises a housing 4, an illumination device 6 and a centre cap 8. The housing 4 is generally cuboid in shape and comprises a front portion 10 and a rear portion 12. The illumination device 6 and the centre cap 8 are received by a recessed part of the front portion 10 of the housing 4, as explained below. The illumination device 6 and the cap 8 define part of an exterior of the housing 4, such that the illumination device 6 is visible by a user. The illumination device 6 is generally ring-shaped and the centre cap 8 is generally circular, such that the centre cap 8 fits within the illumination device. The recessed part of the front portion 10 of the housing 4 is also generally circular, such that the illumination device 6 and centre cap 8 nest securely within the recessed part. The rear portion 12 of the housing 4 comprises four feet 14 located at the corners of the rear portion 12 for mounting the extension speaker against a support surface such as a wall (not shown). The rear portion 12 further defines recesses 16 positioned between each pair of feet 14 and facing towards the support surface. Figure 3 shows a cross-section through the line A-A of Figure 1. As shown in Figure 3, the extension speaker 2 further comprises a sound generating device 18. The sound generating device may be any suitable device for generating sound, for example a loudspeaker. Preferably the sound generating device 18 is able to generate sound in the range of around 60 dB to 80 dB for ordinary use when the alarm system has not been tripped, and up to around 80 dB to 120 dB for generating an alarm sound when the alarm has been tripped. The sound generating device 18 is positioned within the recessed part of the front portion 10 of the housing 4. The sound generating device 18 is oriented to face rearwardly, towards the support surface, and is supported by an annular seat 19 surrounding an aperture 20. The aperture 20 of the front portion 10 of the housing 4 is aligned with a corresponding aperture 22 of the rear portion 12 of the housing 4 such that sound generated by the sound generating device 18 passes through both apertures 20, 22 and is reflected by the support surface (not shown) whereupon the sound waves are deflected outwards, passing through the recesses 16 between the feet 14 of the rear portion 12 of the housing 4. Because the recesses 16 are defined by the rear portion 12 of the housing 4 and face towards the support surface the recesses 16 promote sound propagation but are not easily accessible from the front of the external sounder, therefore making access to the inside of the external speaker 2 by an intruder more difficult. The sound generating device 20 is further supported by three rearwardly extending ribs 24 of the centre cap 8 (only one of which is visible in the cross-section of Figure 3). The centre cap 8 comprises a plurality of hollow bosses 26 which are aligned with corresponding hollow bosses 28 of the front portion 10 of the housing 4. During use, fasteners 30 are passed through the hollow bosses 28 of the front portion 10 of the housing 4 and screwed into the corresponding bosses 26 of the centre cap 6 to compressively fasten the centre cap 8 to the front portion 10 of the housing 4. In doing so, the ribs 24 of the centre cap 8 urge the sound generating device 18 against the annular seat 19 to ensure firm mechanical contact therebetween. This contact prevents the sound generating device 18 rattling relative to the front portion 10 of the housing 4 and ensures clearer sound transmission. With reference to Figures 3 and 4, the illumination device 6 comprises a plurality of first illumination sources 26, second illumination sources 28 and third illumination sources 30 positioned on a PCB 32. The first illumination sources 26 are configured to selectively emit coloured light in the range of around 520 nm to around 580 nm and preferably around 571 nm, corresponding to green light, and the second illumination sources 38 are configured to selectively emit light in the range of around 620 nm to around 700 nm and preferably around 631 nm, corresponding to red light The first and second illumination sources 26, 28 are embodied in bicolour LEDs positionable as single components on the PCB 30 but comprising separate light emitting portions having separate electrical inputs and outputs (hence, each light emitting portion of the bicolour LEDs is regarded as a separate illumination source for the purposes of illustrating the invention). The bicolour LEDs have a luminous intensity of around 30 med to around 50 med, which is sufficiently bright enough that the emitted light is clearly visible to the user even in well-lit areas (that is to say, so that the bicolour LEDs are able to function as indicators visible to the user). The third illumination sources 30 are LEDs configured to emit white light (i.e. a mixture of wavelengths over the range of about 390 nm to about 700 nm). The white LEDs have a power output of around 2 cd to around 3 cd, which is bright enough to sufficiently illuminate an area surrounding the extension speaker so that the user can see even in low light conditions (that is to say, the white LEDs are bright enough to function as a room light or a flood light). The illumination device 6 comprises four bicolour LEDs defining four first illumination sources 26 and four second illumination sources 28, and four white LEDs defining four third illumination sources. The bicolour LEDs and the white LEDs are arranged in an alternating circular pattern around the circumference of the PCB 32. The illumination device 6 further comprises a light diffuser 34. The light diffuser 34 is generally ring-shaped and extends around the circumference of the PCB 32. The light diffuser 34 comprises eight arches 36, each arch 36 being positioned directly over one of the illumination sources 26, 28, 30. The light diffuser 34 is made from a translucent polymer material configured to internally scatter light received from the light sources 26, 28, 30 so that the light spreads out around the light diffuser 34. To this end, the material of the light diffuser 34 may comprise reflective particulate additives to promote internal scattering. Preferably, surfaces of the arches 36 are smooth to promote light transmittance into the light diffuser 34. Preferably, the radially inner and outer cylindrical surfaces and the bottom planar surface of the light diffuser 34 are also smooth to promote internal reflection of light so that the light scatters further. Additionally, a top surface 38 of the light diffuser 34 may be textured to provide improved scattering of light leaving the light diffuser 34. The PCB 32 comprises a plurality of mounting holes 40 which partially receive the bosses 26 of the centre cap 8 and the bosses 28 of the front portion 10 of the housing 4. The bosses 26, 28 and mounting holes 40 prevent rotation of the PCB 32 relative to the housing 4 to ensure all components mounted to the PCB 32 are in the correct position. Additionally the centre cap 8 comprises ribs 42 which urge the PCB 32 against the front portion 10 of the housing 4 to prevent rattling of the PCB 32 relative to the housing 4. The PCB 32 comprises a central aperture 44 which receives part of the sound generating device 18 and through which the ribs 24 of the centre cap 8 extend in order to engage the sound generating device 18. Figure 5 shows the extension speaker 2 from the reverse side (i.e. from the perspective of the support surface) with the rear portion 12 of the housing 4 removed. The reverse side of the front portion 10 of the housing 4 defines a pair of hooks 46 and a clip 48 which act as cable tidies for electrical wiring within the housing 4. The extension speaker 2 further comprises a pair of terminal blocks 50 configured to receive electrical inputs from wires connected to a control panel of the alarm system (not shown). The terminal blocks 50 comprise pins 52 which pass through the PCB 32 for electrical connection to the PCB 32, as shown in Figure 4. The extension speaker 2 further comprises a connection plug 54 for the sound generating device 18. The connection plug 54 is electrically and mechanically mounted to the PCB 32 and is, in particular, a standard-type female connector configured to receive a corresponding standard-type male connector of the sound generating device 18. However, in alternative embodiments, the sound generating device may be connected directly to the PCB 32 without the use of male I female connectors, for example by soldering. Figure 6 shows the extension speaker 2 from the reverse side with the rear portion 12 of the housing 4 attached. The rear portion 12 of the housing 4 comprises a pair of cable entry holes 55 through which the wiring connecting the terminal blocks 50 to the control panel are passed. Each foot 14 of the rear portion 12 of the housing 4 comprises a mounting hole 56. The mounting holes 56 are through holes configured to receive a fastener (e.g. a wall screw or the like) therethrough to fix the rear portion 12 of the housing 4 to the support surface. The mounting holes 56 are slightly elongate (or “lozenge-shaped”) to permit the rear portion 12 of the housing 4 to be adjusted once the fasteners are in place so that it is level with respect to the floor. One of the feet 14 (in the embodiment shown, the bottom right foot 14) comprises a separable portion 58 defining the relevant mounting hole 56. The separable portion 58 is a part of the rear portion 12 of the housing 4 that has been mechanically weakened so as to break away from the remainder of the rear portion 12 of the housing 4 during a tamper event, such as for example if an intruder attempts to remove the extension speaker 2 from the support surface. In the embodiment shown, the separable portion 58 is connected to the remainder of the rear portion 12 of the housing 4 by only three relatively narrow bridges 60 such that the separable portion 58 is frangibly connected to the remainder of the rear portion 12 of the housing 4. When the extension speaker 2 is pulled from the support surface, the separable portion 58 will remain attached to the support surface due to the fastener passing through the mounting hole 58, causing the bridges 60 to fail under shearing. However, in alternative embodiments substantially any suitable mechanical weakness may be used to define the separable portion 58. For example, the separable portion 58 could be defined by one or more score lines configured to frangibly separate from the rear portion 12 of the housing 4, or the separable portion 58 could be a separate component to the rear portion 12 of the housing 4 that rests within the rear portion 12 of the housing 4 using bendable legs or the like which will deform in response to a pulling force. Figure 7 shows a cross-section of the extension speaker 2 through the line B-B of Figure 1. As shown in Figure 7, the frangibly separable portion 58 comprises an upwardly protruding leg 62. When the front and rear portions 10, 12 of the housing 4 are coupled to one another, as shown, the leg 62 engages an arm 64 of a tamper detection device in the form of a tamper switch 66 to place the tamper switch 66 in a closed position. As shown in Figure 5, the tamper switch 66 is mounted to the front portion 10 of the housing 4 and is electrically and mechanically connected to the PCB 32, and communicates with the control panel of the alarm system via wires running from the terminal blocks 50 to the control panel. The tamper switch 66 is aligned with the frangibly separable portion 58 of the rear portion 12 of the housing 4. With reference back to Figure 7, when a tamper event occurs, for example if an intruder attempts to pull the external speaker off the support surface, the frangibly separable portion 58 will break away from the remainder of the rear portion 12 of the housing 4 such that the leg 26 will disengage the arm 64 causing the tamper switch 66 to open. The control panel will detect that tamper switch 66 has opened and, if armed, will trigger an alarm accordingly. Alternatively, the tamper event may involve the intruder attempting to uncouple the front portion 10 of the housing 4 from the rear portion 12 of the housing 4 (leaving the rear portion 12 attached to the support surface), in which case the leg 62 will disengage the arm 64 in the same manner as above, such that the alarm will sound. The front portion 10 of the housing 4 comprises a tamper surround 68 peripherally surrounding the tamper switch 66. The tamper surround 68 protrudes rearwardly from the front portion 10 of the housing 4 towards the rear portion 12 of the housing 4 such that the tamper surround 68 is axially overlapped with the leg 62. The tamper surround 68 is configured to prevent access to the tamper switch 66 from the outside by an intruder, so that it is not possible to insert a shim or another object to keep the tamper switch 66 closed as the front portion 10 of the housing 4 is separated from the rear portion 12 of the housing. Although the tamper detection device above is embodied as a tamper switch 66, it will be appreciated that in alternative embodiments the tamper detection device may comprise substantially any suitable device for detecting a tamper event, such as for example a pressure switch, optical sensor, vibration sensor, accelerometer, strain gauge or the like. Figure 8 is a plan view of the rear portion 12 of the housing 4 from the obverse side (i.e. facing the support surface). The rear portion 12 of the housing 4 comprises a hook 70, a pair of internal walls 72 and arrow markers 74. The hook 70 acts as a cable tidy for wires that have been passed through the cable entry holes 55. The internal walls 72 are positioned at right angles to one another either side of the frangibly separable portion 58. Together with the arrow markers 74, the internal walls 72 make clear which part of the housing 4 contains the tamper switch, and guide the installer to route any wiring that has passed through the cable entry holes 55 away from the tamper switch 66. The internal walls 72 extend forwardly from the rear portion 12 of the housing 4 towards the front portion 10 of the housing 4 and may additionally provide a further barrier against interference by an intruder. The rear portion 12 of the housing 4 comprises a pair of orthogonally oriented miniature spirit levels 78 to help the installer ensure that the housing 4 is level against the support surface. Finally, the rear portion 12 of the housing 4 further comprises a pair of hooks 80 configured to couple the rear portion 12 of the housing 4 to a corresponding formation of the front portion 10 of the housing 4 to secure the two together. The terminal blocks 50 enable the extension speaker 2 to be electrically connected to the control panel of the alarm system. As can be seen from the above, the extension speaker 2 does not comprise any independent power source, such as a battery, and does not connect to a power supply separate to the control panel. As such, the extension speaker 2 receives all of its electrical power through wiring connected to the terminal blocks 50. Each terminal block 50 comprises four contact terminals. One of the terminal blocks 50 is configured to provide electrical communication between the control panel and the LEDs and the other of the terminal blocks 50 is configured to provide electrical communication between the sound generating device 18 and the control panel and between the tamper switch 66 and the control panel. Regarding the illumination device 6, the anodes of all three types of illumination sources 26, 28, 30 are connected via the PCB 32 to a single contact terminal of one of the terminal blocks 50. The cathodes of all of the first illumination sources 26 are connected together in parallel and connected to a single contract terminal of the terminal block 50 via the PCB 32, the cathodes of all of the second illumination sources 28 are connected together in parallel and connected to a single contract terminal of the terminal block 50 via the PCB 32, and finally the cathodes of all of the third illumination sources 30 are connected together in parallel and connected to a single contract terminal of the terminal block 50 via the PCB 32. The four contacts of the terminal block 50 are electrically connected via separate wires to the control panel of the alarm system. Series resistors may be included between the cathodes and the contact terminals to limit the current flow therethrough. During use, the control panel feeds a constant input voltage, for example 12 V to the anodes of the illuminations sources 26, 28, 30 via the corresponding contact terminal. When no illumination is required, the control panel sets the impedance of the contact terminals for the cathodes of all three types of illumination source 26, 28, 30 to be high (akin, for example, to an open circuit). As such, no current flows across the illumination sources 26, 28, 30 and therefore the illumination device 6 remains unilluminated. When it is desired to switch on one of the types of illumination source 26, 28, 30, the control panel pulls the voltage at the relevant contact terminal down to 0 V, causing current to flow through the relevant illumination source 26, 28, 30 so that it is illuminated. The voltage of the relevant contact terminal can be adjusted continuously between 0 V and the input voltage so as to vary the power supplied to the illumination sources 26, 28, 30 and therefore also the brightness of the illumination sources. By switching the relevant contact terminal to 0 V, the control panel effectively outputs an illumination driving current that causes current to flow across the relevant illumination source 26, 28, 30 so that it is illuminated. This configuration is generally known as a “switched negative” control, however it will be appreciated that in alternative embodiments substantially any suitable configuration for illumination the illumination sources 26, 28, 30 may be used, for example a “switched positive” control or the like. Controlling the illumination state of each type of illumination source 26, 28, 30 enables the illumination device 6 to display a plurality of different lighting patterns corresponding to an output of the alarm system. For example, when the alarm system is disarmed, all of the illumination sources 26, 28, 30 may be switched off. When the alarm system is in entry or exit mode, the first illumination sources 26, which are green, may be lit up. Additionally, if the control panel detects that the door to a porchway has been opened (which may occur simultaneously with entry or exit mode), the third illumination sources 30, which are white, may be lit up to illuminate the porchway. When the user has left the building and the alarm is armed the first and second illumination sources 26, 28, which are green and red, may be illuminated to display yellow light for a predetermined period of time after entry or exit mode has finished (for example, two or three minutes). When the alarm has been tripped due to the detection of an intruder, the second illumination sources 28, which are red, may be lit up. Additionally, the control panel may be connected to a proximity sensor configured to sense the presence of the user as they approach an entrance to the building, and may use this as an input for activating the third illumination sources 30 for illuminating the area surrounding the entrance. Generally speaking, it will be appreciated that the control panel may control substantially any one or any combination of colours, brightnesses, positions, flashing rates of the illumination device 6 to display a lighting pattern. Although the all of the individual illumination sources 26, 28, 30 within in type of illumination source 26, 28, 30 are connected in parallel, it will be appreciated that in alternative embodiments each individual illumination source may be separately controllable. That is to say, each LED on the PCB 32 may be separately addressable, such that further lighting patterns are possible. Furthermore, the illumination device 6 may include additional illumination sources of different colours or brightnesses. For example, the illumination device 6 may comprise an illumination source configured to emit blue light in the range of around 400 nm to around 520 nm, in addition to, or in place of the third illumination source. By including a blue illumination source along with red and green illumination sources, the illumination device 6 may be able to produce substantially any colour of light. In addition to controlling the lighting pattern of the illumination device 6, the sound emitting device 18 of the extension speaker 2 is configured to generate a plurality of auditory signals that can be heard by the user. The sound generating device 18 may be activated in the same manner as the illumination device 6, and in particular is activated in response to a sound-driving current output by the control panel. The auditory signals may vary due to substantially any suitable audio property, for example loudness, tone, tempo or the like. The auditory signals may correspond to a particular output of the alarm system, such as those discussed above in relation to the illumination device. Because the extension speaker 2 of the present invention is able to produce both auditory and visual signals, the extension speaker has multiple means for communicating with the user and is therefore easier and simpler to use. Additionally, the use of audio and visual signals means that in the event of a failure of either the illumination device 6 or the sound generating device 18 (which may have been cased for example by an intruder) the extension speaker 2 is still able to communicate with the user. The use of audio and visual signals also means that the extension speaker is suitable for use both by users that have hearing problems and users that have sight problems.

Claims

1. An extension speaker for an alarm system, comprising:a housing with a front portion and a rear portion that are separable from one another, the rear portion having a separable portion configured to separate5 from the rear portion of the housing in response to a tamper event;a sound generating device positioned within the housing;an illumination device at least partially defining an exterior of the housing and viewable by a user;wherein the sound generating device is configured to generate sound in10 response to a sound driving current output by the control panel, the sounddriving current being a current that contains the waveform of the sound and the electrical power required to generate the sound using the sound generating device at a desired volume, and the illumination device is configured to display a lighting pattern in response to an illumination driving current output by the15 control panel, the illumination driving current being a current that provideselectrical power required to illuminate the illumination device in one or more lighting patterns, the extension speaker solely being powered by the output current from the control panel; anda tamper detection device configured to detect a tamper event, the tamper20 event detection device being comprised of a switch that is closed by couplingthe front and rear portions of the housing to one another and opened by uncoupling the front and rear portions of the housing from one another, and the switch being configured to open in response to a separable portion being separated from the rear end of the housing.25 2. An extension speaker according to claim 1, wherein the illumination device isconfigured to display a plurality of lighting patterns, each lighting pattern corresponding to an operational state of the alarm system.

3. An extension speaker according to claim 2, wherein the illumination device is configured to generate the plurality of lighting patterns in dependence upon a30 plurality of outputs of the control panel.03 12 244. An extension speaker according to any preceding claim, wherein the illumination device comprises a first illumination source configured to emit coloured light at a first wavelength and a second illumination source configured to emit coloured light at a second wavelength different to the first wavelength.5 5. An extension speaker according to claim 4, wherein the first illumination sourceis substantially collocated with the second illumination source.

6. An extension speaker according to claim 4 or 5, wherein the illumination device comprises a plurality of first illumination sources and a plurality of second illumination sources, each one of the first illumination sources being collocated 10 with each one of the second illumination sources to define a pairing, and eachpairing being spaced apart from one another.

7. An extension speaker according to claims 4 to 6, wherein the illumination device comprises a third illumination source configured to emit white light.

8. An extension speaker according to claim 7, wherein the illumination device 15 comprises a plurality of third illumination sources spaced apart from oneanother.

9. An extension speaker according to claim 8, wherein each pairing of the first and second illumination sources and each one of the third illumination sources are arranged in an alternating pattern.20 10. An extension speaker according to any preceding claim, wherein housingcomprises a cap, and wherein the illumination device comprises a plurality of illumination sources arranged around the perimeter of the cap.

11. An extension speaker according to any preceding claim, wherein the illumination device comprises a light diffuser configured to diffuse light emitted 25 by an illumination source.

12. An extension speaker according to claim 11, wherein the light diffuse comprises a translucent light-scattering material.

13. An alarm system comprising:the extension speaker of any preceding claim; andcma control panel configured to output the sound driving current and / or illumination driving current in response to an operating condition of the control panel.

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