WO2021079109A1

WO2021079109A1 - Covers for safety/security devices

Info

Publication number: WO2021079109A1
Application number: PCT/GB2020/052644
Authority: WO
Inventors: Peter Alexander; Clym Brown
Original assignee: Texecom Limited
Priority date: 2019-10-23
Filing date: 2020-10-21
Publication date: 2021-04-29
Also published as: GB2589064B; GB201915328D0; GB2589064A

Abstract

An outer cover is provided to cover the housing of a security/safety sensor device. The cover is configured to be fastened over the housing of the security/safety sensor device and can be used to alter its appearance. The outer cover can be used to provide branding over the security/safety sensor device, in which case it can be transparent or translucent and provided with a decorative insert, sandwiched between the cover and the housing. Alternatively, the cover can make a safety/security device intended for mounting on a wall appear suitable for ceiling mounting. For example, the cover may be of circular outline and clip over a housing of rectangular outline.

Description

Covers for safetv/security devices

Technical Field of the Invention

The present invention relates to covers, in particular to covers for security devices, especially in safety and security sensors and most especially, but not exclusively, in passive infra-red motion detectors (known in the art as PIRs, which stands for Passive Infrared Receivers). The invention also relates to safety/security devices comprising such covers.

Background to the Invention

Various safety/security sensor devices are known. For example, safety sensors such as fire sensors and carbon monoxide sensors detect fires and high levels of CO respectively, and security sensors such as PIRs and microwave detectors detect movement in a detection zone (e.g. associated with an intruder).

Passive infra-red motion detectors are security devices used in alarm systems to detect movement, which can be indicative of an intruder, and relay a corresponding signal to a control panel, so as to trigger an alarm, for example.

Passive infra-red motion detectors for use in alarm systems are typically of two- part design, with a housing having a front section and a rear section. The rear section is attached to a wall or ceiling and the front section is removable from the rear section, e.g. for set-up or servicing.

The two parts are typically slid together to connect, or pivoted together to connect. A fastener is normally provided to hold the two parts together - in some examples, the fastener may be a simple screw, sometimes a captive screw held in one part; in other examples, a lock-type arrangement is provided, where the fastener can comprise the barrel of a lock, the barrel being accessible by a key, such as a simple screwdriver which can twist the barrel to undo a latch to allow the two parts to be disconnected, for example, removing a barrier to relative sliding, or removing a barrier to a push-clip disconnection.

Moving the two parts of the housing away from each other generally triggers a tamper- signal, for example triggered by a connector on one part disconnecting from a corresponding connector on the other part (especially in wired PIRs) or (more often for wireless PIRs) by movement causing a feature on one part to interact (or cease to interact) with a feature on the other, effectively opening or closing a switch.

In many designs, all the electronics of the device are provided on the rear section, with the front section merely a (normally plastic) lid, sometimes including a lens. In other designs, the electronics, or most of the electronics are provided in the front section, along with the optical system for the infrared sensor (normally a lens or mirrored optics). A benefit of this arrangement with electronics in the front is that the electronics can be provided in a casing, such that they are mechanically shielded by the housing at the front and the casing at the back, by shielding the electronics, they are not exposed when the PIR is installed and are less likely to be damaged. Also, in a wired arrangement, removal of the front section from the rear section can disconnect the electronics (on the front) from the wiring on the rear section and improving tamper- evidence (as the breaking of the connection can trigger a tamper signal). Moreover, where the electronics of the front section is updated, an updated front section can be replace the existing front section, by simply clipping in in place of the old front section, without the need to remove or re- wire the rear section.

PIRs often have lights (typically LEDs) associated with them, which flash to indicate that they are active, triggered etc. These lights can be positioned behind the lens, so as to be visible (when lit) through the lens, which is normally translucent, but opaque to the eye in the absence of light from a LED, so that the electronic components behind the lens cannot be seen. Alternatively, lights may be provided behind separate transparent or tinted window/light guide in the front section to provide a more attractive display, for example more uniform light.

The design of PIRs is normally subtle, in order that they can blend into any interior, typically they are white and normally as small and unobtrusive as possible. Branding, if any, is normally subtle too. On occasion certain safety and security equipment, such as control panels may be branded by a manufacturer with an installer’ s name, e.g. by printing directly onto the equipment. This achieves a high-quality appearance, but complicates stock-keeping as any such branded equipment can only be sold to the installer concerned. Smaller installers, who do not purchase in sufficient volumes to persuade a manufacturer to brand their equipment with the installer’s name/logo might put stickers on the equipment, in order to give exposure to their company, but this may not be done professionally and can have an impact on the perceived quality of the equipment. Branding is only very infrequently applied to PIRs or other safety and security sensors, which avoids this issue, but is considered to represent a missed opportunity.

The housings of PIRs that are intended for mounting on a wall are typically of a generally quadrilateral shape e.g. rectangular in outline; this is considered to be most suitable for mounting normally in the top comers of rooms, where they can be neatly lined up with the straight edges where two walls meet, or a wall meets the ceiling. The housings of PIRs that are intended to be mounted on the ceilings, on the other hand, are normally circular in outline, this avoids any need to line them up with walls, which could be tricky since they are often spaced some distance from the nearest walls.

Thus, although the electronics within the housing may be identical as between those for wall mounting and those for ceiling mounting, manufacturers have two separate lines for manufacture, requiring more space, must submit both products for separate regulatory testing, and manufacturers, as well as distributors/installers must keep sufficient stock of both types (although typically ceiling mounted products might make up no more than 2-5% of sales). This increases costs and complexity throughout the supply chain.

The present invention seeks to overcome or at least ameliorate one or more problems with the prior art and/or to provide an improved safety/security device.

Summary of the Invention

According to a first aspect of the invention, there is provided an outer cover for a security/safety sensor device comprising a housing, the cover configured to be fastened over the housing of the security/safety sensor device.

Such an outer cover, which can be provided over the housing of a complete security/safety sensor device, can be used to alter its appearance. For example, an outer cover can be used to provide branding over the security/safety sensor device, or can make a safety/security device intended for mounting on a wall appear suitable for ceiling mounting (e.g. it may be of circular outline and clip over a housing of rectangular outline).

The cover may be at least partially, or completely, transparent or translucent. The cover may be provided with a decorative insert, such as a branding insert arranged to be sandwiched between the cover and the housing. In this way, branding can be provided in a professional manner by printing high-quality inserts, which is substantially less costly than printing direct to a housing (which is so difficult that most manufacturers do not normally print the branding of installers on their products, unless they sell a very high volume). Moreover, a branding insert can be changed more easily to update the brand of the installer/distributor.

The insert can be formed of vinyl sheet, which is long-lasting. The insert (e.g. vinyl sheet) can be digitally printed to a high quality. Alternatively, paper or board, could be used which are flat media readily available and easily run through all sorts of printers, with different designs printed cheaply.

The cover may be of the same shape or outline as the housing. This means that the inserts can be easily sandwiched within.

The cover may be of a different shape or outline to the housing. In particular, the cover may have a circular shape or outline. The cover may be configured to be fastened over a housing with a rectangular shape or outline. The cover may be at least partially, or completely, opaque. As outlined above, the cover can be used to make a safety/security device with a rectangular shape (intended for mounting on a wall) suitable for mounting on a ceiling - a circular and opaque cover is preferred for this purpose as it disguises the rectangular shape of the housing beneath. Nonetheless, a transparent/translucent cover, or partially transparent/translucent cover, in combination with a suitable insert could achieve the same overall effect of disguising the shape of the housing beneath, whilst also providing a branding opportunity.

Regardless of the shape of the cover it can be opaque. An opaque cover may have a decorative surface finish or may be patterned. As such, an opaque cover can be used, instead of as a branding exercise, to better match interior decoration. For example, an opaque cover could be printed in a colour better matching the decoration; or coated, by known techniques e.g. to mimic other surface characteristics, such as wood grain or carbon fibre, or even coated with a decorative material like gold leaf.

Notably, this means that a single safety/security sensor device, e.g. one with a rectangular housing can be manufactured on a single automated line and can be submitted to the testing authorities, e.g. to be certified to security grades 2 and 3 under the EN 50131-2-2 certification in the case of a PIR or EN 50131-2-4 certification in the case of a dual technology, passive infrared and microwave, sensor device. The manufacturer, distributor or installer can then keep a stock of e.g. circular opaque covers and fasten these to the housing of the tested device so as to change the appearance without necessitating any further testing (since the housing and the internal components are unchanged). This improves the supply chain and stock-keeping requirements for all concerned.

The cover may be provided with an aperture to expose an optical system (such as a lens) of the security/safety sensor device and/or a light of the security/safety sensor device (such as an LED or light guide connected to a light source of the security/safety sensor device). This avoids the cover having any detrimental effect on focussing. The aperture may be circular. A circular aperture can match a lens and/or a light guide with a circular outline, such as a part-spherical lens, and a toroidal light guide arranged around the part-spherical lens, which can work and look acceptable on a wall-mounted sensor device as well as suiting a ceiling-mounted device.

The cover may comprise at least one fastener, for example two fasteners. The or each fastener may be an integral fastener. The or each fastener may be a rib or a clip. The or each rib or clip may be configured to engage with a corresponding groove in the housing of the security/safety sensor device. For example, the or each clip may be arranged to clip into a groove provided by the shut-line/split-line between a front section and a rear section of the housing, or the or each rib may be arranged to twist into engagement with a groove provided by the shut-line/split-line between a front section and a rear section of the housing.

The cover may be may be tray- shaped, having a generally planar face with one or more raised edges. The aperture may be provided in the generally planar face. It may be provided centrally in the generally planar face. The or each fastener may be provided on one or more raised edge. The or each fastener may be provided on an internal surface of the or each raised edge. The insert may have a shape or outline corresponding to the shape or outline of the generally planar face. It may have an aperture corresponding to the aperture in the generally planar face.

A second aspect of the invention provides a security/safety sensor device comprising a housing and an outer cover therefor; the cover configured to be fastened over the housing of the security/safety sensor device.

The cover may include any of the optional features described in relation to the first aspect and the safety/security device may include any of the optional features described in relation to the first aspect. Likewise, where applicable, the following optional features apply not only to the second aspect of the invention but also to the first aspect.

It will be appreciated that the cover and the security/safety sensor device may be sold separately, but it is useful to refer to them in combination.

The housing may house a sensor. The housing may house a signal processor. The housing may house at least one of a transmitter, a receiver, a transceiver or a relay. The housing may include a tamper device operable in the event that the housing is opened. The tamper device may be configured not to be triggered by the removal and/or application of the outer cover.

As discussed above, it is intended that the housing is a complete security/safety sensor device which does not require the cover to function. In consequence it is preferred that it includes all the essential features within the housing, such as those mentioned above, and that opening the housing triggers a tamper alarm, whereas the user/installer should be free to apply or remove the cover and any insert without triggering the tamper alarm, because the function of the device should not be impacted by the cover.

The security/safety sensor device may be a PIR. The housing may therefore comprise electronics. For example, it may comprise an infrared sensor. It may comprise a microwave sensor. It may comprise an optical system. The optical system may be a lens. The optical system may be mirrored optics. The security/safety sensor device may comprise a light, such as an LED, so as to provide feedback to an installer/user.

The housing may comprise a front section and a rear section. There may be a split line between the front section and the rear section. The split line may be configured to receive a fastener, such as one or more rib or clip, of the cover, such that the cover is fastened to the housing by interaction of fastener (e.g. the rib(s) or clip(s)) with the split line (e.g. the clips clipping into the split line or the ribs twisted into the clip line). To achieve this, the split line may be at least 1mm, at least 1.5mm, at least 2mm, at least 2.5mm or at least 3mm wide.

This is unusual as split lines are normally intended to be as small as possible, just as panel gaps on cars are as small as possible to reflect precision engineering. However, it allows for this additional purpose of the split line, acting as a fastener and avoiding the need for further fastening means on the housing, which could be aesthetically unpleasant in the normal operation of the housing without the cover applied.

The optical system (e.g. a lens) may be provided in the front section of the housing. The electronics of the device may be mounted behind the optical system (e.g. a lens) in the front section of the housing of the device.

The lens may be circular in outline. The lens may be part-spherical, e.g. hemispherical. The housing may be generally rectangular in shape or outline.

The electronics may be mounted in a casing. The casing may be provided within the inside of the front section of the housing. It could alternatively be provided on the rear section.

The front section and the rear section may be movable between an operational configuration and a non-operational configuration. For example, in the operational configuration the front and rear sections may be connected together and in the non- operational configuration the front and rear sections may be disconnected, or at least partially disconnected. The tamper alarm may trigger a tamper signal in the event of unauthorised movement between the operational configuration and the non-operational configuration.

The front section and/or the rear section may be tray- shaped, having a generally planar face with raised edges. The split line may be provided where the raised edges meet.

The front section, for example the generally planar face thereof, may be provided with an aperture, behind, in, or through which the sensor is arranged. Other electronic components, such as a signal processor, and/or a transmitter/receiver/transceiver/relay may be arranged behind the generally planar face of the front section, optionally in the casing. The generally planar face of the front section may thereby separate the components from the lens and protect them when the lens is removed.

The housing may have a front and a rear; it may have a top and a bottom; it may have sides. The cover may cover (or at least partially cover) the front of the housing (e.g. where the housing is for attachment to a wall, at the face furthest from the wall, or where the housing is for attachment to a ceiling at the face furthest from the ceiling). The cover may cover, or at least partially cover the sides. The split line may be provided in the sides. Detailed Description of the Invention

In order that the invention may be more clearly understood one or more embodiments thereof will now be described, by way of example only, with reference to the accompanying drawings, of which:

Figure 1 shows a front-perspective view of a passive infra-red motion detector; Figure 2 shows a side view of the passive infra-red motion detector of figure 1; Figure 3 shows an underneath view of the inside of the passive infra-red motion detector of figures 1-2;

Figure 4 shows a plan view of the inside of two halves the passive infra-red motion detector of figures 1-3 in its open state, looking from front to back at the rear section and from back to front at the front section (and at a slight angle to each);

Figure 5 shows a front view of the passive infra-red motion detector of figures 1- 4 and front views of an insert and an outer cover according to a first embodiment;

Figure 6 shows a close-up inside perspective view of the outer cover of figure 5;

Figure 7 shows a close-up underneath perspective view of the passive infra-red motion detector of figures 1-6 with the outer cover fastened thereto and the insert sandwiched between the motion detector and the cover;

Figure 8 shows a front perspective view of the passive infra-red motion detector of figures 1-4 and front perspective views of an insert and a cover according to a second embodiment of the invention;

Figure 9 shows an inside perspective view of the cover of figure 8;

Figure 10 shows a close-up side-perspective view of the cover of figures 8 and 9 attached to the passive infra-red motion detector of figures 1-4; and

Figure 11 shows a front view of the cover and insert of figure 8 attached to the passive infra-red motion detector of figures 1-4.

Referring to figures 1-4, a safety/security sensor device in the form of a wired passive infra-red motion detector (hereafter a “PIR”) 1 is illustrated. The PIR 1 is of two-part construction formed from a housing having a front section 2 and a rear section 3 (e.g. by injection moulding a plastics material). The PIR 1 comprises an optical system in the form of a lens 4 facing forward from the front of the front section 2 of the housing.

As shown in figure 4, a casing 5 is provided internally, i.e. at the back of the front section 2 of the housing, encasing electronics, including an infra-red sensor (not shown), a signal processor (not shown) and a transceiver (not shown). Certain parts of the electronics extend through the casing so as to be accessible from the inside when the housing is open, such as adjusters 6, 7, and, from the top of the casing, extending upwards, a connector 8. In this embodiment, the front and rear sections 2, 3 of the housing are both of generally rectangular tray- shaped form, with a generally planar face having raised edges at both the long sides and shorter ends. The PIR 1 is intended, normally, to be wall-mounted with its long sides vertical, a top end at the top and a bottom end at the bottom - in the orientation shown in figures 1 and 2. As shown in figures 2 and 4, various holes (or regions in which an installer can form holes) 18 are provided through the rear section 3, so that it can be attached to a wall by conventional means (e.g. screw fasteners extending from the interior of the housing through the rear section 3 into the wall). However, it is to be understood that this generally rectangular form is not essential and that the PIR 1 would work in other orientations.

The raised edges of the front section 2 abut the raised edges of the rear section 3 when assembled, defining a cavity within. A split line 17 is provided where the raised edges of the front section 2 meet the raised edges of the rear section 3.

To connect the front section 2 to the rear section 3, as shown in figure 4, the front section 2 is provided with two tabs 9 extending upwardly in-use into the cavity from the rim of the edge at the bottom end; the two tabs 9 are arranged to co-operate with, a pair of corresponding apertures 12 in projections 10, which extend forward/outward in-use from the rear section 3, the tabs 9 extending up through the apertures in the projections 10, in use.

Similarly, the rim of the edge at the top end of the rear section 3 is provided with two tabs 11, which extend downward in-use, into the cavity. These tabs 11 co operate in a similar fashion with apertures 13 provided in projections 14, which extend rearward in-use. In consequence, the two sections 2, 3 of the housing can be attached together, and brought from a non-operational configuration to an operational configuration, by a sliding connection, with the front section 2 placed slightly out of registration with the rear section 3, below it, then slid up into registration with the rear section 3; the projections 9 of the front section 2 entering the apertures 12 of the rear section, and the projections 11 of the rear section 3 entering the apertures 13 of the front section 2.

A housing-fastener 15, best seen in figures 3,4 and 7, is provided at the bottom of the rear section 3. The housing-fastener 15 has a barrel which extends through an aperture in the base of the rear section 3 and includes a latching finger extending laterally from the barrel and movable between a latched position and an unlatched position.

Movement between the latched and unlatched positions is achieved by rotating the fastener 15, in this case using a flat-blade screwdriver introduced into a slot in the base of the fastener, visible in figure 3 and accessed from below the PIR 1.

Extending around the periphery of the front section 2, from the inside edge of the raised edges thereof, between a respective projection 14 at the top and a respective tab 9 at the bottom, is a shoulder 19. In use, these shoulders 19 sit just inside the sides of the raised edges of the rear section 3, so as to provide a barrier to access to the inside of the housing of the PIR 1 through the split line 17. Similarly, at the periphery of the rear section, from the inside edge of the raised edges thereof, a shoulder 20 extends across the top of the rear section 3, between its tabs 11, so as, in use, to provide a barrier to access to the inside of the housing through the split line between the projections 14 at the top of the front section, and another shoulder 20 extends across the bottom of the rear section 3 between its projections 10, so as, in use, to provide a barrier to access to the inside of the housing through the split line in the gap between the shoulders 19 of the rear section 3 at the bottom of the device.

As shown in figure 4, terminal block 16 is mounted in the rear section 3, near its top end. In view of the sliding connection of this embodiment, the terminal block 16 is provided with a connector having an opening, which in a use-configuration faces downward, so as to receive the upwardly extending connector 8 of the front section 2, when the two sections are slid into attachment. Accordingly, detaching the front section 2 from the rear section 3 (moving it from the operational condition to the non- operational condition) disconnects the electronics from the terminal block 16. Since in use the terminal block will be wired to a control panel (not shown) of an alarm system, this disconnection can be detected from a loss of signal and appropriate action can be taken e.g. the alarm may be triggered or a fault signal emitted to indicate apparent tampering with the PIR 1.

Whilst described above as “generally rectangular” and formed with “generally planar” faces, it will be noted from figures 2 and 3 that the front section 2 and rear section 3 of the housing have slightly more complex shapes than simple rectangular trays with raised edges extending from strictly planar faces.

In more detail, and as best illustrated by figures 2 and 3, the generally planar surface of the front section of the housing of the PIR 1, is broadly rectangular, but with outwardly bulging rounded top and bottom ends; it is convex, curving outwards, forwards from its sides and ends (as best shown in figure 2).

For its part, whilst the generally planar face of the rear section 3 is flat in the middle, it is chamfered at its lateral edges, so that it can either be attached to a single flat wall via the central part, or attached to two walls where they meet via the two chamfered parts. Moreover, the raised edges of the rear section 3 are curved to correspond to the curve of the raised edges of the front section 2.

The lens 4 extends forward from the centre of the front section 2 and is shaped as a spherical dome, with a circular outline when viewed from the front, with the origin of the circle being in the same position as the centre-point of the generally rectangular outline of the housing. A toroidal light-guide 21, best seen in figure 1 is provided around the lens 4, with its origin in the same position, so as to emit light from a light source such as an LED (not shown) within the housing in a circle around the lens 4 (to provide visual feedback to a user/installer). In consequence, the front of the front of the housing has left-right reflectional symmetry and up-down reflectional symmetry, as well as rotational symmetry about 180 degrees.

Turning now to figures 5-7, a first embodiment is shown of an outer cover 22 and an insert 23, which, in figure 5 can be seen alongside the PIR 1 of figures 1-4; the outer cover 22 and insert 23 configured to be applied to the housing of the PIR 1 to provide a means of providing branding of a temporary, replaceable nature on the PIR 1 in a manner which will appear professional.

The insert 23 is a simple sheet of vinyl, cut to the shape of the outline of front of the housing of the PIR 1, with a central perforation 24 corresponding to size and location of the lens 4 and the toroidal light guide 21, such that the insert 23 can be arranged on the front surface of the front section 2 of the PIR 1 without interfering with the lighting effect form the light guide 21 or the detection of IR radiation through the lens 4. A logo 25 is printed onto one side of the insert 23 using a suitable printing process. The logo 25 may be that of the manufacturer, but more likely that of an installer, or possibly a distributer. It may be digitally printed on behalf of the installer or distributer by the manufacturer, in order to ensure a sufficiently high-quality print. The inserts 22 are replaceable (without opening the housing of the PIR 1 and activating a tamper- alert), so they can be changed by an installer/service engineer, or even potentially by a user, such as a householder, to better match interior decoration. The inserts 23 could be printed on both sides, e.g. with alternative logos/colours on opposing sides, or with a decorative face on one side (e.g. showing the logo) and a non-decorative face on the other side (e.g. printed with instructions or information).

The outer cover 22 holds the insert in place. It is transparent, so that the insert is visible. In this embodiment, the outer cover 22 is entirely transparent, formed of a suitable transparent plastic material (such as acrylic). However, those skilled in the art will appreciate that it could be partially transparent, so as to provide a window through which the logo 25 on the insert 23 can be seen, whilst concealing the remainder. It could feasibly even be opaque, with an opening through which the insert can be seen.

The outer cover 22 has a shape corresponding to the front section 2 of the housing of the PIR 1. It is, therefore, generally rectangular and generally tray-shaped, with a generally planar (but strictly convex) front face, shaped and sized to conform to the front face of the front section 2 and raised edges shaped and sized for a close fit around the raised edges of the front section 2. The raised edges of the outer cover 22 are raised to the extent that, in use, they span the split line 17 and follow the shape of the split line 17 around the housing of the PIR. At the rim of the raised edges of the outer cover 22, a pair of clips 26 are provided. The two clips 26 are arranged on the short edges of the generally rectangular outer cover and offset from the centre. The clips 26 are diametrically opposed, so one is offset towards the left and the other towards the right when looking face-on. The clips 26 extend inwards from the rim of the raised edges, towards the middle. The plastic of the outer cover 22 is slightly resilient, so as it is pressed onto the front of the front section 2, the clips move ever so slightly outwards, then, once the rim of the raised edges aligns with the split line 17, the clips 26 return to their natural position, moving slightly inwards, so as to clip into the split line 17 and thereby hold the cover 22 in place on the front of the front section.

The outer cover 22 is also provided with a central aperture 27, which aligns with the perforation 24 in the insert 23 and the lens 4 and light guide 21 in the PIR 1, so as not to interfere with light or IR radiation.

In use, the printed insert 23 is placed into the tray-shaped outer cover 22, with the decorative face that is intended to be visible facing the transparent generally planar face of the outer cover. The outline of the insert 23 conforms to that of the outer cover 22, so the raised edges of the cover 22 keep it centralised. The cover 22 is then introduced onto the housing of the PIR 1, such that the lens 4 extends through the perforation 24 in the insert, and the aperture 27 in the outer cover, and pushed in until the clips 26 engage with the split line 17 and the insert 23 is sandwiched between the housing of the PIR 1 and the outer cover 22.

Referring now to figures 8-11, a second embodiment is shown of an outer cover

32 and an insert 33, which can be seen alongside the PIR 1 of figures 1-4 in figure 8; in the second embodiment, the outer cover 32 is a circular outer cover 32, and the insert

33 is a circular insert 33. The circular outer cover 32 and circular insert 33 are configured to be applied to the housing of the PIR 1, not only to provide a means of providing branding of a temporary, replaceable nature on the housing of the PIR 1 in a manner which will appear professional, but also to render the PIR 1 suitable for use as a ceiling-mounted PIR 1.

The circular outer cover 32 of this embodiment is intended to hold the circular insert 33 in place and is transparent, so that the insert 33 is visible. However, it should be well understood that in this embodiment, where the function of the circular outer cover 32 is to alter the apparent shape of the housing of the PIR 1, it could certainly alternatively be opaque and used without an insert 33. (Again, it could be partially transparent, so as to provide a window through which a logo 35 on the insert 33 can be seen, whilst concealing the remainder or opaque, with an opening through which the logo 35 on the circular insert 33 can be seen. Importantly, and unlike the outer cover 22 of the first embodiment, the circular outer cover 32 has an outline which does not correspond to the front section of the housing of the PIR 1 - instead, it is circular. However, aspects of the shape of the circular outer cover 32 do correspond to the shape of the front section 2 of the housing of the PIR 1.

In particular, the circular outer cover 32 has a central circular aperture 34, which corresponds to the diameter and location of the toroidal light guide 21 which surrounds the lens 4 (so as not to obscure these parts when installed and thereby not to interfere with light or IR radiation). Moreover, the circular outer cover 32 is generally tray shaped, with a generally planar (but strictly convex) front face. Furthermore, whilst the front face is annular in outline, the convex curvature of the front face is shaped and sized to conform to the shape of the front face of the front section 2, and a raised edge 36 extending from the periphery of the annular face is sized for a close fit around the bulges at the top and bottom of the front section 2. The raised edge of this embodiment is ridged, with ridges oriented linearly from the front face to the rim. The ridges are textured, e.g. frosted. The provision of ridges and the frosting hide what could otherwise be seen through the rim, (i.e. the PIR 1 beneath), which may be considered ugly, or look unprofessional, otherwise. The ridges also appear as a deliberate design feature, whilst achieving this result.

The raised edge of the outer cover 32 is raised to the extent that, in use, it extends beyond the split line 17, so as to substantially cover the majority of the raised edges of both the front section 2 and rear section 3 of the housing of the PIR 1. Rather than clips at the rim of the raised edge 36, the circular outer cover is provided with ribs 37 (best seen in figure 9) to engage with the groove provided by the split line 17.

A pair of ribs 26 are provided, diametrically opposed and protruding radially inwards from the raised edge 36. The ribs 26 are elongate, with their elongate axis extending circumferentially around the inside of the raised edge and being spaced from the rear of the generally planar front face of the outer cover by approximately the same distance as the split line 17 is spaced from the front face of the front section. In consequence, the outer circular cover 32 can be arranged over the housing of the PIR 1 with the ribs 26 initially facing the long sides of the generally rectangular, in outline, housing of the PIR 1, then twisted so that the ribs 26 (simultaneously) come into contact with the split line 17 at the comers (as shown in figure 10) and become engaged/wedged into the split line 17, securing the circular outer cover 32 onto the housing of the PIR 1.

The circular insert 33 is a simple sheet of vinyl, cut to the shape of the outline of the annular front face of the circular outer cover 32. The insert 33 has a cut 38 extending from the outer edge to the inner perforation 39, which allows it to better conform to the convex shape of the rear of the annular front face of the circular outer cover 32 and the front of the annular front face of the housing of the PIR 1, between which, in use, it is sandwiched. The central perforation 39 of course corresponds to the size and location of the lens 4 and the toroidal light guide 21, such that the insert 33 can be arranged on the front surface of the front section 2 of the housing of the PIR 1 without interfering with the lighting effect form the light guide 21 or the detection of IR radiation through the lens 4. A logo 35 is printed onto one side of the insert 33 using a suitable digital printing process and, as in the first embodiment, the logo 35 may be that of the manufacturer, but more likely that of an installer, or possibly a distributer. It may be printed on behalf of the installer or distributer by the manufacturer, in order to ensure a sufficiently high-quality print. The circular inserts 33 are replaceable (without opening the housing of the PIR 1 and activating a tamper- alert), so they can be changed by an installer/service engineer, or even potentially by a user, such as a householder, to better match interior decoration, and, as with the first embodiment, again, the inserts 33 could be printed on both sides, e.g. with alternative logos/colours on opposing sides, or with a decorative face on one side (e.g. showing the logo) and a non-decorative face on the other side (e.g. printed with instructions or information).

In use, the printed insert 33 is placed into the tray-shaped outer cover 32, with the decorative face that is intended to be visible facing the transparent generally planar face of the outer cover. The outline of the insert 33 conforms to that of the outer cover 32, so the raised edge of the cover 32 keeps it centralised. The cover 32 is then introduced over the housing of the PIR 1, such that the lens 4 extends through the perforation 39 in the insert, and the aperture 34 in the outer cover, and the ribs 37 face the long sides of the housing of the PIR 1. The cover 32 is then twisted to bring the ribs into engagement with the split line 17 at opposing corners of the housing of the PIR 1 and then wedged into position in the groove formed by the split line 17, with the insert 33 is sandwiched between the housing of the PIR 1 and the outer cover 32 as shown in figure 11.

Whichever cover 22, 32 is to be attached, an installer can install the PIR 1 in the usual fashion, i.e. he/she locates the location where the PIR 1 is to be installed, typically the comer of a room with the cover 22 of the first embodiment or the ceiling with the cover of the second embodiment. The installer will already have wired a cable with all the necessary wires from a security alarm control panel (not shown) to the location. If the PIR 1 has been supplied with the front section 2 and rear section 3 attached, the installer detaches the front section 2 from the rear section 3 of the housing of the PIR 1 and selects which apertures 18 that are to be used to mount the PIR 1, then marks the wall (not shown) and introduces suitable fastenings into the wall (e.g. wall plugs), optionally first drilling holes in line with the marks. A cable (not shown) is then threaded through the central top hole and wired into the terminal block 16. Screws (not shown) are introduced through the selected holes 18 to attach the rear section 3 of the housing to the wall.

Having made any necessary adjustments/settings using the adjusters 6, 7 on the front section 2, the front section 2 is then located with its back facing the front of the rear section 3 and disposed slightly out of registration with the rear section 3, then slid such that the connector 8 of the front section 2 enters the opening of the terminal block 16 in the rear section 3 and respective projections 9, 11 enter respective apertures 12, 13, until the front section and rear section 3 are in registration, as shown in figure 1. The housing fastener 15 is then turned to maintain the closed state.

The relevant cover 22, 32 (and associated insert 23, 33) can then be attached as outlined above.

The alarm system can then be switched on, and light from the light guide 21 will be emitted uniformly around the lens 4 and will be visible through the apertures/perforations in the associated cover 22, 32 and insert 23, 33. In the event that it is desired to change the cover 22, 32 or insert 23, 33, the cover can be unfastened and a new insert introduced before re-fastening it, or replaced with a completely new cover, without any need to open the housing of the PIR and thereby trigger the tamper-alarm. It will be appreciated that this offers various improvements over the prior art, primarily that a wall-mounted PIR can be adapted to provide a professional and easily replaceable branding or other decorative appearance, and optionally adapted to function as a ceiling-mounted PIR, with no need for separate testing/certification, because the cover is completely separate to the PIR itself and does not affect its functionality. The one or more embodiments are described above by way of example only.

Many variations are possible without departing from the scope of protection afforded by the appended claims.

Just as one example, the invention is by no means limited to use with wired PIRs, but could equally be used with wireless PIRs (or other safety/security sensing devices), although an alternative approach to detecting movement to the non- operational configuration would be required (those skilled in the art will have no difficulty devising such tamper-indicating systems).

Claims

1. An outer cover for a security/safety sensor device comprising a housing, the cover configured to be fastened over the housing of the security/safety sensor device.

2. An outer cover for a security/safety sensor device according to claim 1 which is at least partially transparent or translucent.

3. An outer cover for a security/safety sensor device according to claim 2 which is provided with a branding insert arranged to be sandwiched between the cover and the housing.

4. An outer cover for a security/safety sensor device according to any preceding claim wherein the cover is of the same shape or outline as the housing.

5. An outer cover for a security/safety sensor device according to any of claims 1- 3 wherein the cover is of a different shape or outline to the housing.

6. An outer cover for a security/safety sensor device according to claim 5 wherein the cover has a circular shape or outline and is configured to be fastened over a housing with a rectangular shape or outline.

7. An outer cover for a security/safety sensor device according to any preceding claim which is at least partially opaque and is either patterned or has a decorative surface finish.

8. An outer cover for a security/safety sensor device according to any preceding claim wherein the cover is provided with a circular aperture to expose an optical system and/or a light of the security/safety sensor device.

9. An outer cover for a security/safety sensor device according to any preceding claim wherein the cover comprises at least one fastener.

10. An outer cover for a security/safety sensor device according to claim 9 wherein the or each fastener is a rib configured to engage with a corresponding groove in the housing of the security/safety sensor device; the groove formed by a split line/shut line between a front section and a rear section of the housing and the or each rib being arranged to twist into engagement with the groove.

11. An outer cover according to claim 9 wherein the or each fastener is a clip configured to engage with a corresponding groove in the housing of the security/safety device, the clip being arranged to clip into a groove provided by the shut-line/split-line between a front section and a rear section of the housing.

12. An outer cover according to any preceding claim which is tray- shaped, having a generally planar face with one or more raised edges.

13. An outer cover according to claim 12 when dependent directly or indirectly on claim 8 wherein the aperture is provided centrally in the generally planar face.

14. An outer cover according to claim 12 or 13 when dependent directly or indirectly on claim 9 wherein the or each fastener is provided on an internal surface of one or more raised edge.

15. An outer cover according to any of claims 12 to 14 when dependent directly or indirectly on claim 3 and claim 8 wherein the insert has a shape or outline corresponding to the shape or outline of the generally planar face and an aperture corresponding to the aperture in the generally planar face.

16. A security/safety sensor device comprising a housing and an outer cover therefor; the cover being an outer cover according to any preceding claim, configured to be fastened over the housing of the security/safety sensor device.

17. A security/safety sensor device comprising a housing and an outer cover therefor according to claim 16 wherein the housing houses a sensor, a signal processor; at least one of a transmitter, a receiver, a transceiver or a relay; and a tamper device operable in the event that the housing is opened.

18. A security/safety sensor device comprising a housing and an outer cover therefor according to claim 17 wherein the tamper device is configured not to be triggered by the removal and/or application of the outer cover.

19. A security/safety sensor device comprising a housing and an outer cover therefor according to any of claims 16 to 18 wherein the security/safety sensor device is a PIR and wherein the housing comprises electronics including an infrared sensor; the PIR further comprising an optical system and a light, so as to provide feedback to an installer/user.

20. A security/safety sensor device comprising a housing and an outer cover therefor according to any of claims 16 to 19 wherein the housing comprises a front section and a rear section; wherein there is a split line between the front section and the rear section; and wherein the split line is configured to receive one or more rib or clip of the cover, such that the cover is fastened to the housing by interaction of the rib(s) or clip(s) with the split line.

21. A security/safety sensor device comprising a housing and an outer cover therefor according to claim 20 wherein the split line is at least 1.5mm wide.

22. A security/safety sensor device comprising a housing and an outer cover therefor according to any of claims 16 to 21 wherein a lens is provided in the front section of the housing and electronics of the device is mounted behind the lens in the front section of the housing of the device; wherein the lens is hemispherical; and wherein the housing is generally rectangular in shape or outline.

23. A security/safety sensor device comprising a housing and an outer cover therefor according to claim 22, 19 or any claim dependent directly or indirectly on claim 19 wherein the electronics is mounted in a casing; the casing being provided within the inside of the front section of the housing

24. A security/safety sensor device comprising a housing and an outer cover therefor according to claim 20 or any claim dependent thereon wherein the front section and the rear section are movable between an operational configuration and a non-operational configuration; and wherein a tamper alarm is operable to trigger a tamper signal in the event of unauthorised movement between the operational configuration and the non-operational configuration.

25. A security/safety sensor device comprising a housing and an outer cover therefor according to any of claims 16 to 24 wherein the front section and the rear section are tray- shaped, having a generally planar face with raised edges and a split line provided where the raised edges meet; the housing having a front and a rear; a top and a bottom; and sides, with the split line provided in the sides; and wherein the cover covers the front of the housing and at least partially covers the sides.