GB2597713A

GB2597713A - Smoke alarm

Info

Publication number: GB2597713A
Application number: GB2011881.6A
Authority: GB
Inventors: Bolger Chris
Original assignee: FireAngel Safety Technology Ltd
Current assignee: FireAngel Safety Technology Ltd
Priority date: 2020-07-30
Filing date: 2020-07-30
Publication date: 2022-02-09
Also published as: GB202011881D0; WO2022023532A1; EP4189657A1

Abstract

An alarm device 10 comprising a housing 12 including a sensing compartment 14 enclosed by a wall component. The sensing compartment 14 comprises at least one sensor component 20,22 and the wall component comprises at least one aperture 24,28 defining a gas passage for external air to reach the sensor component 20,22. The wall component 16 may comprise an exterior housing wall component 16 enclosing a sensing wall component 26, wherein the sensing wall component 26 encloses the sensing compartment 14. At least a portion of the wall component 16 may comprise a pest control substance, which is integral thereto. Sensing wall component 26 and blades 30 may comprise a matrix material such as plastic which may comprise a pest control substance integral thereto. The pest control substance may be an insect repellent. The alarm device 10 may be a smoke detector, heat detector, carbon monoxide detector or carbon dioxide detector.

Description

Smoke alarm

Field of the invention

The present invention relates to an alarm device such as a smoke alarm.

Background

Fire detector devices, such as heat or smoke detectors, are configured to detect a condition indicative of fire, such as heat or smoke, following which an alarm signal is emitted.

The detection of a condition indicative of fire can be interfered with, for example by insects or dust. This can lead to false alerts. It is therefore desirable to reduce interference.

Detector devices have been suggested that contain releasable insect repellent to prevent the ingress of insects. WO 97/09876 discloses a pesticidal alarm device wherein the device contains a removable disc of cardboard impregnated with insecticide. The insecticide is released as a vapour from the cardboard, and in WO 97/09876 it is asserted this would provide an insect-repellent effect lasting for three to six months, after which replacement of the cardboard disc is necessary. JP2005293306 describes an alarm device having a removable portion containing insect repellent. Another alarm device is described in JP2017146925, the alarm device having a removable portion containing insect repellent or repelling means, for example a pyrethoid agent, an organic phosphorus agent, a carbamate agent, a boron compound, or a fluorine compound.

The present invention seeks to further improve known arrangements.

Summary

According to a first aspect, there is provided an alarm device according to claim 1. The alarm device comprises a housing comprising a sensing compartment enclosed by a wall component, wherein the sensing compartment comprises at least one sensor component and the wall component comprises at least one aperture defining a gas passage for air external to the alarm device to reach the sensor component in the sensing compartment.

The sensing compartment will be understood to comprise a chamber in which sensing occurs. It will be appreciated that the at least one sensor component may typically be in the sensing compartment. The sensor component is typically capable of detecting a desired environmental condition, and is typically in communication with an alarm component which emits an alarm signal following detection of the environmental signal. The environmental signal may be indicative of a fire, for example smoke or heat, or may be indicative of a hazardous condition, such as the presence of carbon monoxide.

Typical alarm devices include smoke, heat, carbon dioxide and/or carbon monoxide detectors. The alarm devices function by sensing the smoke, heat, carbon dioxide and/or carbon monoxide, following which an alarm signal is emitted from the device, typically light or sound, in order to alert a user. Smoke detectors and heat detectors are used as indicators of fire.

Optionally, the wall component comprises an exterior housing wall component and a sensing wall component. Typically, the exterior housing wall component forms an exterior housing and surrounds the sensing wall component, the sensing wall component forming the sensing compartment. Optionally, the exterior housing wall component and/or the sensing wall component can include the at least one apertures. In some embodiments, the exterior housing wall component and sensing wall component can be considered to be part of the same component.

Optionally, at least a portion of the wall component comprises a pest control substance which is integral to the wall component.

In some embodiments the entirety of the wall component comprises a pest control substance which is integral to the wall component.

Optionally, the pest control substance is at least 0.5% and optionally no more than 30% by weight of the wall component.

Optionally, the wall component comprises a matrix composite material and the pest control substance is dispersed in the matrix.

Optionally, the wall component comprises a plastic/resin.

Optionally, the pest control substance comprises an invertebrate control substance, such as an insecticide or insect repellent.

Any apertures in the exterior housing wall component are hereinafter referred to as "exterior apertures". Any apertures in the sensing wall component are hereinafter referred to as "interior apertures". The term "apertures" (without specifying exterior or interior) may refer to any interior apertures and/or exterior apertures. Similarly, the term "wall component" without further definition may refer to the exterior housing wall component and/or the sensing wall component.

In some embodiments, the pest control substance is restricted to the sensing wall component and not the exterior housing wall component. Pest control substances sometimes have deleterious side effects upon users in close proximity. Thus, restriction of the pest control substance to the interior of the housing may advantageously prevent users of the device from any detrimental side effects. While not necessarily all substances may be harmful in the relevant concentrations, the ability to position the insect-repellent component inside the housing reduces the need at the design stage to consider the hazard of the repellent substance, whether or not the repellent substance or mix of substances, in the relevant concentration, poses a contact risk to humans.

Optionally, the sensing wall component compartment and/or the exterior housing wall component comprises a coating, the coating optionally comprising a material comprising a pest control substance which is integral to the material of the coating.

The coating material may be the same or different to the material of the sensing wall component and/or exterior housing wall component. For example, the coating may comprise a composite material, and the sensing wall component and/or exterior housing wall component which is coated may comprise a non-composite material. Alternatively, the coating may comprise a composite material and the sensing wall component and/or exterior housing wall component which is coated may comprise a different composite material.

By integral, this will be understood to refer to the pest control substance being part of the wall component. Thus, the pest control substance is unitary to at least a portion of the wall component. i.e. the pest control substance at least partly forms the material of the wall component. The material of the wall component and the pest control substance are combined during manufacture to form a singular material. It will therefore be understood that the pest control substance remains in the device for the lifetime of the device, which can be 10 years or more. Advantageously, therefore, the pest control substance of the device does not need to be replaced at any point in the lifetime of the device. This reduces the cost of maintenance of the device, and also improves ease of maintenance.

In the context of the present invention, the expression "pest" will be understood to refer to a creature which is capable of interfering with the detection of an environmental condition by the device. A "pest" will therefore be understood to include an invertebrate creature having a size of less than 9cm in length. This includes insects, arachnids, and the like.

As used herein, the term "pest control substance" encompasses a substance which is capable of chemically stopping a pest, typically by killing, paralysing, injuring or deterring a pest from a site. The pest control substance may comprise an invertebrate control substance. In some embodiments, the pest control substance comprises a pesticide (i.e. a substance capable of killing pests). In some embodiments the pest control substance comprises a pest repellent (i.e. a substance capable of deterring pests from a site). The pest control substance may be an insecticide or an insect repellent. Example pest control substances include, but are not limited, to pyrethoid agents, an organic phosphorus agent, a carbamate agent, a boron compound, or a fluorine compound. The skilled person will be mindful that certain substances will be more effective against one group of insects than others, and that some substances will be more effective against a range of invertebrates. The skilled person will therefore be able to identify suitable substances, or mixes of substances, that may be appropriate to deter a wide range of pests.

In some embodiments the pest control substance controls pests upon contact of the pest by the pest control substance, i.e. contact by the pest with the portion of the wall component comprising the pest control substance. Alternatively, or in addition, the pest control substance may function to control pests by the slow release of the pest control substance from the wall component. For instance, the pest control substance may be a chemical comprising or breaking down into volatile components that are slowly released from the wall component.

Optionally, the at least one apertures comprises a plurality of apertures each having a width of at least, or in the region of, 1.3 mm.

Optionally, the at least one aperture comprises a single aperture extending around substantially the entirety of a circumference around a central point of the device. The single aperture may not extend beyond a distance of 20 cm around the circumference.

The term "circumference" may refer to a path following the exterior housing wall component or sensing wall component.

Optionally, the exterior housing wall component encloses the sensing wall component and the sensing wall component encloses the sensing compartment.

The sensing compartment of the alarm device may be enclosed by the wall component such that the sensing compartment is internal to the housing.

Optionally, the wall component comprises one or more wall structures arranged to prevent direct light external to the housing reaching the sensing compartment, and further optionally, at least a portion of the one or more wall structures comprises a pest control substance. The pest control substance may be integral to the one or more wall structures.

Optionally, the apertures of the wall component each lead to a channel formed by two or more wall structures, wherein the channel is accessible to pests via the at least one apertures, the channel preferably having a length of 10mm or less. The term "length" refers to the distance at which a pest must travel to traverse completely through the channel.

Generally, the wall component of the housing comprises at least the exterior housing wall component. The exterior housing wall component acts as a cover for the device, such that an external side of the exterior housing wall component faces the exterior of the device. The sensing wall component will be understood to enclose the sensing compartment, such that the sensing wall component is enclosed by the exterior housing wall component. The sensing wall component may be separate and/or attached to the exterior housing wall component. In such embodiments the sensing compartment will be understood to be defined as the interior of the sensing wall component.

Optionally, the alarm device is a smoke detector device and wherein optionally the at least one sensor component comprises an optical detection arrangement, preferably comprising a light emitting member and a light detection member.

In embodiments comprising a smoke detector device, and, where the sensor component comprises an optical detection arrangement, during smoke conditions, smoke enters the sensing compartment via the at least one aperture in the wall component and interferes with the optical detection arrangement. This interference indicates the presence of smoke. In non-smoke conditions, the optical detection arrangement is not obscured and so detection is maintained, indicating that smoke is not present.

The optical detection arrangement may comprise a light emitting member, typically an LED, and a light detection member. The light detection member may comprise a photodiode. The light emitting member may be capable of emitting infrared, ultraviolet or visible light. In non-smoke conditions, the light emitting member emits some light, which is not received by the light detection member. In smoke conditions, the light from the light emitting member is reflected towards the light detection member by the smoke thereby causing the light detection member to receive more light.

In some embodiments, other types of sensor components may be used. For example, the at least one sensor component may comprise an ionization smoke detector.

Optionally, the alarm device is a heat detector device, wherein optionally the at least one sensor component comprises a heat sensor, for example a fixed temperature heat sensor or a rate-of-rise heat sensor.

Optionally, the alarm device is a carbon monoxide (CO) detector device and wherein the at least one sensor component comprises a CO sensor arrangement, preferably comprising a CO electrode.

As the skilled person will appreciate, the housing of fire alarm devices may comprise a base configured for attaching the device to a surface and a control circuit for controlling the operation of the device.

Optionally, the alarm device comprises a configuration to carry out regular signal tests and relate the signal tests to a value indicative of an accumulation of dust.

Many fire detector devices include a mesh containing pores of a size, typically below 1.3 mm, which prevents the ingress of insects into the device. A problem with such meshes is that they also inhibit the ingress of dust into the device. The fact that inhibiting the ingress of dust into the device is a problem may seem counter-intuitive, and so this is explained in more detail. Normally, if dust enters the sensing chamber, dust accumulates slowly over time, and this may lead to a reduction in sensor sensitivity. The sensor sensitivity can be measured, e.g. against a regular test signal, and the sensitivity baseline (or any change in signal-to-noise ratio) can be recalibrated to take account for a baseline change. If the baseline sensitivity becomes too low (i.e. the build-up of dust leads to a decrease of baseline sensitivity that is beyond an acceptable threshold), then as a countermeasure the device can issue a signal that it requires cleaning, which can usually be achieved with a vacuum cleaner or a device capable of blowing out dust from the alarm device. Such a cleaning may be part of a regular service or may be prompted on demand every few years.

Fine mesh structures such as insect-protection gauzes around the sensing chamber prevent the ingress of dust. While the sensing chamber itself is thereby also protected from dust ingress and maintains its sensitivity better than if exposed to gradually accumulating dust, the effectiveness of the overall device may still decrease due to a build-up of dust in the mesh. Densely accumulated dust may block the mesh and inhibit the entry of smoke into the sensing chamber. The build-up of dust on the mesh is not detectable by the sensing chamber and so the base-line calibration of the sensors is not effective. In that case, dust build-up on the mesh can reduce or prevent the detection of conditions indicative of fire.

The purpose of the mesh in known smoke detectors is also to prevent the ingress of pests. The presently claimed device removes the requirement for a mesh, thereby allowing access for dust particles into the sensing compartment while preventing the ingress of insects. In this way, dust and other particles can, and may have to, be regularly removed from the smoke detector. Thus, in some embodiments the device comprises control logic for measuring sensor sensitivity. In some embodiments, the device may comprise a mesh whilst retaining advantages provided by other features according to this disclosure.

The inventor has appreciated that the dust accumulation on fine mesh structures can become a problem, surprisingly for modern alarm devices. This problem has become an issue because modern alarm devices can be battery-powered, without reliance on mains power, in the region of 10 years. Furthermore, an increasing number of modern alarm devices have wireless connectivity permitting remote monitoring and remote testing. Today, the reliability of battery supply and remote monitoring has reached a level that, in turn, has led to the relaxation of regulatory requirements on prescribed inspection intervals for such alarm devices. Modern alarm devices may be in operation without a regulatory requirement for on-site inspection for several years. The inventor appreciated that modern alarm devices may have inspection intervals long enough for a significant dust build-up.

By being able to tolerate larger apertures into the sensing compartment, the invention avoids the clogging of a mesh with dust or other particles and reduces the likelihood of smoke being blocked from reaching the sensor.

In embodiments such as smoke detector device embodiments, the enclosure of the sensing compartment by the wall component ensures that the sensing component remains protected from everyday stimuli (which are not the desired environmental condition for detection) external to the device which could interfere with the sensor component, for example natural or artificial light.

It will, however, be appreciated that in some embodiments, the sensing component extends from the sensing compartment through and beyond the wall component. For example, the alarm may be a heat detector device, and the sensing component may comprise a heat sensor which extends through and beyond the wall component, such that an end of the heat sensor extends into the air surrounding the wall component.

In some embodiments, the alarm device is a CO detector device. In such embodiments the at least one sensor component comprises a CO sensor arrangement. The CO sensor arrangement may comprise a biomimetic CO sensor, a CO-sensing semi conductor or a CO-sensing electrode, preferably a CO electrode.

In some embodiments the device either of the exterior wall component or sensing wall component comprises at least two apertures. In some embodiments the device comprises no more than 100 apertures.

In some embodiments, the exterior wall component may comprise a single exterior aperture that surrounds the entire device.

Any aperture described above may have a rectangular, square, circular or other appropriate shape. The width of the aperture will be understood to refer to the distance between opposing sides of an aperture at its widest point. For example, in a rectangular-shaped aperture, the width will be measured between the two shortest sides of the rectangle. In a circular-shaped aperture, the width can be measured at any given point, provided it is between two opposing sections.

In some embodiments the at least one aperture extends around the circumference of the device or sensing compartment by least 1cm and no more than 20 cm, preferably at least 2 cm and no more than 20 cm. In some embodiments the at least one aperture extends around the circumference of the device or sensing compartment by at least 2 and no more than 3cm. This size of aperture allows the entry of smoke into the device, enabling detection, but also allows the user to access the inside of the device. This allows the user to remove dust and/or other particles as and when necessary from the device. Baseline calibration can also be effected.

Preferably, the sensing wall component comprises at least one aperture enabling air to travel between the exterior housing wall component and the sensing wall component to reach the sensor component in the sensing chamber.

In some embodiments the wall component, for example the exterior housing wall component, comprises wall structures arranged to prevent direct light external to the housing reaching the sensing compartment via the at least one aperture. At least a portion of the wall structure(s) may comprise a pest control substance, the pest control substance being integral to the wall structure(s).

In some embodiments the wall component comprises two, three, four, five or six wall structures. In some embodiments the wall component comprises no more than 10, nine, eight, seven, six or five wall structures.

The wall structures may comprise a light-blocking structure, e.g. blades, each light-blocking structure (e.g. blade) having a proximal end connected to the interior side of the wall component, and a distal end towards the centre region of the interior of the housing. In embodiments comprising a sensing wall component, the proximal end of each blade(s) may be connected to the interior side of the exterior housing wall component and a distal end of each blade(s) may be towards or abut the sensing wall component. Other light-blocking structures are columns with a chevron cross-section or offset, over-lapping wall components. Common to such light-blocking structures is that in combination they provide an indirect passage suitable for smoke to reach the sensing compartment while blocking direct access expected from light rays. The indirect passage also provides a prolonged channel that in the absence of other structures allows ingress of dust and pest such as insects.

The space between adjacent blades forms a channel. Each channel may be accessible to pests via the at least one aperture in the wall component of the housing -i.e. any exterior aperture in the exterior housing and/or any interior aperture in the sensing wall component. Crawling pests are likely to come into contact with the blades if they enter via one of the apertures. Flying pests may theoretically avoid contact and the contact likelihood is increased to near certainty by the following arrangements. In some embodiments the width of the space is 10mm or less, preferably 9mm or less. This provides a narrow channel(s) which increases the likelihood for pests to come into contact with the blade(s). Furthermore, the indirect passage increases the length an insect has to travel before reaching the inside of the sensing compartment, further increasing the likelihood of coming into contact with one of the walls. In embodiments where the blade(s) comprise a pest control substance, this ensures that the pests are repelled, paralysed or killed.

In some embodiments each of the blades comprises a non-linear shape, for example an S shape. This results in a contorted channel and a contorted path for the pests to follow. This increases the likelihood of a pest contacting the wall further, which is especially beneficially when the blade(s) comprise a pest control substance. Other suitable non-linear shapes can be envisaged which are capable of providing such a contorted path.

Optionally, at least 0.5%, and, optionally no more than 30% by weight of the wall component may comprise the pest control substance. In some embodiments at least 1% and no more than 10%, preferably at least 1% and no more than 5% by weight of the wall component comprises the pest control substance. Optionally, at least 1% and no more than 3% by weight of the wall component may comprise the pest control substance.

In some embodiments, the wall component comprises a pest control substance, which is integral to the wall component, and further comprises a composite material. By composite material, this will be understood to refer to a material made from at least one constituent material, the one constituent material having an extra functional group as compared to the original material. Alternatively, the composite material may be understood to refer to a material comprising at least two constituent materials, at least one of the constituent materials comprising a pest control substance. Thus, the pest control substance is unitary to the material, and so is integral to the wall component.

In some embodiments, the composite material comprises a constituent material, such as a polymer or functionalised polymer, wherein the pest control property is provided by a functional group of the constituent material. In the context of the present invention, a functional group will be understood to mean that the pest control substance is linked to a polymer by a covalent bond. However, the pest control property of the pest control substance may be provided by molecules, or by substances bound to a matrix, e.g. covalently or electrostatically.

For example, the composite material may comprise a polymer, such as a plastic, wherein the polymer comprises at least one type of functional group, the at least one type of functional group providing the pest control properties.

In some embodiments the composite material comprises a matrix material. As used herein, matrix will be understood to refer to a material comprising at least one continuous constituent material and at least one discontinuous or dispersed constituent material. The pest control properties may be exhibited by a substance of the matrix and/or a substance of the discontinuous/dispersed material. In such embodiments, the pest control substance may comprise the at least one discontinuous or dispersed material, such that the pest control substance is dispersed in the continuous constituent material. Thus, in some embodiments the wall component comprises a matrix material and the pest control substance is dispersed in the matrix. In some embodiments the exterior wall component comprises a matrix material.

The composite material may comprise a plastic material and/or resin material. The plastic material may comprise thermoplastic material. Suitable plastics include, but are not limited to acrylonitrile butadiene styrene (ABS), acrylic styrene acrylonitrile (ASA), which are commercially available under the trade names Lustran and Novodur, polycarbonate, (PC), and polyethylene, for example, high-density, medium-density or low-density polyethylene. Typically the plastic and/or resin material comprises the continuous constituent material of the matrix.

According to a second aspect there is provided an alarm device comprising a housing comprising a sensing compartment enclosed by a wall component. The sensing compartment comprises at least one sensor component and the wall component comprises at least one aperture defining a gas passage for air external to the alarm device to reach the sensor component in the sensing compartment. At least a portion of the wall component comprises a pest control substance is integral to the wall component.

According to a third aspect there is provided an alarm device comprising a housing comprising a sensing compartment enclosed by a wall component. The sensing compartment comprises at least one sensor component and the wall component comprises at least one aperture defining a gas passage for air external to the alarm device to reach the sensor component in the sensing compartment. The wall component comprises an exterior housing wall component and a sensing wall component. The exterior housing wall component encloses the sensing wall component and the sensing wall component encloses the sensing compartment; and the wall component comprises one or more wall structures arranged to prevent direct light external to the housing reaching the sensing compartment.

Description of the Figures

Exemplary embodiments of the invention will now be described with reference to the Figures, in which: Figure 1 shows an exploded view of an embodiment according to the invention; and Figure 2 shows a perspective view of another embodiment according to the invention.

Detailed Description

Figure 1 shows an alarm device 10 comprising a housing 12 comprising a sensing compartment 14 enclosed by a wall component 16, in this embodiment an exterior housing wall component.

The alarm device 10 exemplified in Figure 1 is represented as a smoke alarm, although it will be appreciated other alarm devices such as a heat alarm or the like may also embody the invention.

In line with features expected in a smoke alarm, the sensing compartment 14 comprises a sensor component 18. It will be appreciated that any positioning of the sensor component 18 in the sensor compartment 14 can be envisaged, provided that the sensor is shielded from unwanted external influences, as necessary. The sensor component 18 is capable of detecting a desired environmental signal, for example smoke, which may be indicative of fire. In this embodiment the sensor component 18 comprises an optical arrangement comprising a light emitting member, for example an LED 20, and a light detection member 22, for the detection of smoke. In other embodiments the sensor component 18 may comprise a heat sensor or a CO sensor.

It will be appreciated that the sensor compartment 14 may be designed and located differently. For instance, heat sensor will typically protrude from the outer housing and the sensor compartment 14 for a heat sensor is typically provided in the form of a cage on the housing, whereas the cage is intended to have a low mass while preventing finger access.

The exterior housing wall component 16 comprises a plurality of exterior apertures 24, each exterior aperture 24 defining a gas passage for air external to the alarm device 10 to reach the sensing compartment 14. In this embodiment the sensing compartment 14 is enclosed and defined by a sensing wall component 26 separate to, but enclosed by, the exterior housing wall component 16. In other embodiments no sensing wall component is provided. The sensing wall component 26 also comprises a plurality of interior apertures 28 each defining a gas passage for air between the exterior housing wall component 16 and the sensing wall component 26 to reach the sensor component 18 in the sensing compartment 14. Each exterior aperture 24 of the exterior housing wall component 16 preferably has a width x of at least 1.3 mm or 2-3cm. This is large enough to blow out dust or to apply a suction device such as a vacuum cleaner to remove dust and other particles as necessary. The determination of when the removal of other dust and other particles is necessary is effected by signal processing, which will be discussed in more detail below. In this embodiment each interior aperture 28 of the sensing wall component 26 has a smaller thickness than each exterior aperture 24 of the housing wall component 16; however, it will be appreciated that other dimensions can be envisaged.

In examples (not shown), the at least one aperture comprises a single aperture extending substantially around a circumference about a central point of the device, the circumference extending substantially perpendicular to the direction of light entering the device. The single aperture may follow either the sensing wall component 26 or exterior housing wall component 16.

Each adjacent interior aperture 28 of the sensing wall component 26 is separated by a blade or spoke 30 extending radially inwards from the sensing wall component 26. Each spoke 30 constitutes a light-blocking structure. In the present configuration, each spoke 30 has a proximal end, attached to the inside side of the sensing wall component 26, and a distal end pointing towards the centre of the sensing compartment 14. In this embodiment each spoke 30 has the same length and does not extend to the centre of the sensing compartment 14; however, different arrangements, shapes and lengths are within the scope of the invention and can be envisaged by the skilled person For example, in some embodiments each of the blades may comprise an S shape. This results in a contorted channel and a contorted path for the pests to follow.

In this embodiment, the sensing wall component 26 and blades 30 comprise a matrix material, in this example a plastic. The plastic can comprise a pest control substance which is integral to the plastic material of the sensing wall component 26 and the blades 30. In this embodiment the pest control substance comprises an insect repellent, but it will be appreciated that other pest control substances are within the scope of the present invention. In some embodiments, there is no pest control substance in the alarm device 10. However, the example discussed in relation to Figure 1 relates to an embodiment including a pest control substance.

As is evident from Figure 1, the space between adjacent blades 30 forms a channel. Each channel is accessible to insects/pests via the at least one exterior aperture 24 in the exterior housing wall component 16. This increases the likelihood for insects to contact the blade(s). As can be imagined, a crawling insect or spider will come into contact if it enters via a channel between the spokes/blades 30. Flying insects may theoretically avoid contact but the longer and the narrower the channel, the more likely it is for flying insects to come into contact with a blade. In the present embodiment the insect repellent is not released from the device. As such, the pest-repellent property relies on increasing the occurrence of a contact. Thus, the narrow channels encourage insects to contact the device, which in turn repels them from the device. Advantageously, the use of an insect repellent rather than a pesticide in the interior of the device ensures that there is not a build-up of dead insects inside the device, which could otherwise be detrimental to the baseline sensing or block the smoke-ingress channel.

In alternative embodiments, the pest control substance may function by slow release from the material. This advantageously steadily releases the pest control substance into the immediate vicinity of the device, thus preventing pests from contacting any surface of the device. This also prevents pests entering the device which could affect baseline sensing. It will, of course, be appreciated that other combinations and embodiments can be envisaged by the skilled person. For example, the exterior housing wall component may comprise a pesticidal substance which is not released from the component. Thus, upon contact with the exterior side of the housing wall component, pests will be killed and thus prevented from entering the device. The present inventor appreciated that the amount of volatile substance to be released can be reduced by a design that limits the volume to the narrow smoke ingress channels.

Thereby, practically, the pest-repellent can be designed as a slow-release mechanism because it is not necessary to ensure the volume of the entire device is filled with an effective concentration of volatile pest repellent. Rather, limiting the volumes to the smoke ingress channels allows the overall release rate to be reduced, and so even pest control substances relying on delivery of a sufficient concentration of volatile substances can be manufactured that last for a long period of time. By avoiding the need for a release of volatile substance, or by reducing the need for a high concentration in a large device volume, the pest-repellent effect can be maintained for longer periods of time. This period of time can be designed to correspond to several years, corresponding to the battery life of an alarm device.

In this embodiment the pest control substance is limited to the sensing wall component and the blades 30 of the sensing wall component 26. Hence, in this embodiment, although the exterior housing wall component also comprises plastic, this does not contain a pest control substance. Advantageously, by restricting the pest control substance to the interior of the device 10, this impedes accidental contact exposure of pest control substance to a person touching the alarm device 10 and so reduces and practically prevents any deleterious side effects to the operator.

It will, however, be appreciated that in other embodiments both the sensing wall component 26 and the exterior housing wall component 16 may comprise the same material, the material comprising a pest control substance. Alternatively, the sensing wall component 26 and the exterior housing wall component 16 may comprise different materials, both materials comprising a different material comprising a pest control substance. In other embodiments the sensing wall component 26 and the exterior housing wall component 16 may comprise different materials, one of the materials comprising a pest control substance and the other material not comprising a pest control substance.

In other embodiments a coating may be applied to one or more components of the device, for example the exterior housing wall component 16 and/or the sensing wall component 26, the coating comprising a pest control substance which is integral to the material of the coating.

In the present embodiment, 2% by weight of the material of the sensing wall component 26 and the blades 30 comprises the pest control substance, although it will be appreciated that other percentages can be envisaged. In this embodiment the material of the sensing wall component 26 and the blades 30 comprises a thermoplastic, for example ASA, mixed with the pest control substance, such that the thermoplastic forms a continuous phase and the pest control substance forms a dispersed phase. Other materials can be envisaged.

Within the housing 12 is also provided a control circuit 32 for controlling operation of the device 10. The control circuit 32 is in communication with the sensor component 18 and an alarm component 34. The sensor component 18 is in communication with the alarm component 34 such the alarm component is configured to emit an alarm signal following detection of the environmental signal by the sensor component 18. The control circuit 32 may comprise a data connection with an external server (not shown) although it will be appreciated that embodiments of the invention may not require a server.

The control circuit 32 comprises control logic for regular re-calibration of the sensor component 18 to ensure that the level of internal dust and/or particles acts a baseline sensitivity level. For instance, the control circuit 32 may measure the signal strength of the sensor component against a baseline calibration value. The signal strength may be repeated every 10 minutes. If the signal strength is less than a threshold value, e.g. lower than 75%, relative to the baseline calibration value, or if the signal strength is less a threshold value for two or more consecutive readings, this may be indicative of a build-up of dust. In that case, the control circuit 32 may generate a notification to alert a user that inspection of the device is required.

Some examples of this disclosure provide for a build-up of dust to be allowed to occur in the sensing wall compartment 26. Thereby, a build-up of dust can be detected by the sensor component 18. At the same time, false alerts due to interference with insects are reduced, and practically avoided, by incorporating an integral pest repellent that acts for a prolonged period of time.

The device is capable of being connected to a power source, for example battery or mains power.

In use, the alarm device 10 is attached to a surface of a domestic dwelling and is connected to a power source, for example mains power. Air external to the alarm device 10 enters the plurality of exterior apertures 24 in the exterior housing wall component 16 and then enters the plurality of interior apertures 28 in the sensing wall component 26 to reach the sensing component 18 in the sensing compartment 14.

When the environmental signal is not present On the present embodiment, smoke, but alternative conditions can be envisaged). the air which enters the sensing compartment 14 does not contain smoke and so the light emitted by the light emitting member 20 is not reflected to be received by the light detection member 22. No (or a preset low amount) of light is received by the light detection member 22 and therefore no alarm signal is emitted by the alarm component, thereby indicating that no smoke is present.

When smoke is present, this smoke enters the plurality of exterior apertures 24 in the housing wall component 16 and then enters the plurality of interior apertures 28 in the sensing wall component 26 to reach the sensing component 18 in the sensing compartment 14. The smoke in the sensing compartment 14 reflects light towards light detection member 22 from the light emitting member 20. Therefore, the light detection member 22 receives an increased amount of light. This causes the alarm component 34 to emit an alarm signal, thus indicating that smoke is present.

In prior devices, dust, other particles and/or pests could also enter the sensing compartment 14 of the device 10 via apertures. For a pest, for example, this could enter by crawling or flying. This can also scatter/reflect the light emitted by the light emitting member 20 towards the light detection member 22, causing the alarm component to emit a false alarm signal either immediately, or upon the build-up of dust or other particles over time.

In examples of this disclosure, a pest approaches the device 10 and enters the exterior apertures 24. Upon contact with the sensing wall component 26, the insect is repelled and leaves the device 10. This prevents the pest from causing reflection of light within the sensor component 18 and so prevents false alerts from pests. In embodiments where the pest control substance is integral to the device, this effect is maintained for the lifetime of the device. In embodiments where the device contains no pest control substance, an insect may be deterred merely due to contact with the sensing wall component 26 In other embodiments, the pest control substance is slowly released from the device. This prevents the pest from entering the device 10 despite the exterior apertures 24 and interior apertures 26 being sufficiently large for an insect to pass.

In preferred examples, the device 10 does not have an insect mesh as would be usually expected from smoke detectors of the type depicted. However, in other examples, the device comprises an insect mesh. For example, a relatively coarse insect mesh may be utilised to prevent particularly large insects from entering the apertures, however the pest control substance is typically, but not necessarily, relied upon to repel smaller insects that can fit through the mesh.

Thereby the invention allows dust and other particles to still enter the device 10 via the apertures more easily, without blocking or clogging the apertures as might otherwise be observed with a particularly fine mesh. This allows the control logic in the alarm device to regularly re-calibrate the device to ensure that the level of internal dust and/or particles acts a baseline sensitivity level. The size of the apertures (and preferable absence of a fine mesh) facilitates removal of dust and/or other particles accumulated inside the optical chamber, for example by vacuum cleaning. This allows, counterintuitively, a controlled build-up of dust and/or other particles inside the sensing chamber so the influence of the dust on the sensitivity can be measured and, if required, dust can be removed.

Describing the control logic in more detail, in use, in the present embodiment the control circuit 32 regularly communicates with the sensor component 18 to instruct the sensor component 18 to carry out a test sense/signal. The test sense/signals may be carried out at regular intervals, for example in the region of every 9 seconds, every minute, every hour, every day, every week, every fortnight or every month. In the present embodiment the test sense/signal is carried out in the region of every 9 seconds. The test signal is communicated back to the control circuit 32. Either the control circuit or a server can then compare the test signal to a baseline comparison of either a reference signal or one or previous signals. In the present embodiment the control circuit 32 is used to compare the test signal to a baseline comparison level, the baseline comparison level stored in the control circuit 32. In examples, the test signals may be carried out relatively frequently, e.g. every 9 seconds. The baseline comparison level may be based on a set of test signal readings and therefore updated more infrequently such as once a month.

In the present embodiment it will be appreciated that the sensor component 18 is sensitive to light. Thus, a reduced sensitivity is indicative of reduced light because of a build-up of dust or other particles.

Once the test signal is reduced to equal to or below a threshold value, the control circuit 32 emits an maintenance signal to let the user know that maintenance of the device to remove the built up dust and/or other particles is due. The maintenance signal may be in the form of a light arrangement, for example a flashing light.

Alternatively, a maintenance signal may be emitted once the test signal is at a certain percentage below one Or more previous signals. In some embodiments the maintenance signal is emitted once the test signal is at 25% or lower of two consecutive previous signals.

In the example of Figure 1, the exterior wall component 16 and sensing wall component 26 are represented as separate components. However, in examples (not shown), they may be part of a single wall component.

Figure 2 shows another alarm device 10 according to the present invention. The alarm device 10 is identical to the device of Figure 1, except that in this embodiment the exterior housing wall component 16 comprises a material comprising a pest control substance which is integral to the material. In this embodiment the sensor wall component 14 (not shown), does not comprise a pest control substance. In this embodiment the pest control substance is an insect repellent, but it is slowly released from the exterior housing wall component 16 into the atmosphere. Thus, in use, as insects approach the device 10, they are deterred from even touching or entering the device 10. The device 10 also comprises vents 36, 38 and 42 for further enabling passage of air to the sensing compartment 14. In this embodiment a user interface 40 is used to reset or turn off the alarm component 34. An unshown user interface may be used to reset the maintenance signal, once the interior of the device has been cleaned, while another user interface (not shown) may be used to turn off the alarm. Other suitable uses for the user interfaces may be envisaged.

There is also disclosed an alarm device substantially as described above, however being substantially formed utilising methods such as three-dimensional printing technology in order that components such as the sensing compartment and wall component are formed by a singular component.

Claims

CLAIMS: 1. An alarm device comprising a housing comprising a sensing compartment enclosed by a wall component, wherein the sensing compartment comprises at least one sensor component and the wall component comprises at least one aperture defining a gas passage for air external to the alarm device to reach the sensor component in the sensing compartment.
2. An alarm device according to claim 1, wherein the wall component comprises an exterior housing wall component and a sensing wall component, wherein the exterior housing wall component encloses the sensing wall component and the sensing wall component encloses the sensing compartment.
3. An alarm device according to any preceding claim, wherein at least a portion of the wall component comprises a pest control substance, which is integral to the wall component.
4. An alarm device according to claim 3, wherein the pest control substance is at least 0.5% and optionally no more than 30% by weight of the wall component.
5. An alarm device according to any of claims 3 or 4, wherein the wall component comprises a matrix material and the pest control substance is dispersed in the matrix.
6. An alarm device according to any of claims 3 to 5, wherein the wall component comprises a plastic/resin.
7. An alarm device according to any of claims 3 to 6, wherein the pest control substance comprises an invertebrate control substance, such as an insecticide or insect repellent.
8. An alarm device according to any of claims 3 to 7, wherein the sensing wall component and/or the exterior housing wall component comprises a coating, the coating comprising a material comprising the pest control substance which is integral to the material of the coating.
9. An alarm device according to any preceding claim, wherein the at least one aperture comprises a plurality of apertures each having a width of at least 1.3 mm.
10. An alarm device according to any preceding claim, wherein the at least one aperture comprises a single aperture extending around substantially the entirety of a circumference around a central point of the device.
11. An alarm device according to any one of the preceding claims, wherein the wall component comprises one or more wall structures arranged to prevent direct light external to the housing reaching the sensing compartment.
12. An alarm device according to claim 11 when dependent on claims 3 to 8, wherein at least a portion of the pest control substance is integral to the one or more wall structures.
13. An alarm device according to claim 11 or 12 comprising two or more wall structures, wherein a space between the two or more wall structures forms a channel that is accessible to pests, the channel preferably having a length of lOmm or less.
14. An alarm device according to any one of the preceding claims, wherein the alarm device is a smoke detector device and wherein the at least one sensor component comprises an optical detection arrangement, preferably comprising a light emitting member and a light detection member.
15. An alarm device according to any one of claims 1 to 13, wherein the alarm device is a heat detector device and wherein the at least one sensor component comprises a heat sensor.
16. An alarm device according to any one of claims 1 to 13, wherein the alarm device is a carbon monoxide (CO) detector device and wherein the at least one sensor component comprises a CO sensor arrangement, preferably comprising a CO electrode.
17. An alarm device according to any one of the preceding claims, comprising a configuration to carry out regular signal tests and relating the signal tests to a value indicative of an accumulation of dust.
18. An alarm device comprising a housing comprising a sensing compartment enclosed by a wall component, wherein the sensing compartment comprises at least one sensor component and the wall component comprises at least one aperture defining a gas passage for air external to the alarm device to reach the sensor component in the sensing compartment wherein at least a portion of the wall component comprises a pest control substance which is integral to the wall component.
19. An alarm device comprising a housing comprising a sensing compartment enclosed by a wall component, wherein the sensing compartment comprises at least one sensor component and the wall component comprises at least one aperture defining a gas passage for air external to the alarm device to reach the sensor component in the sensing compartment, wherein the wall component comprises an exterior housing wall component and a sensing wall component, wherein the exterior housing wall component encloses the sensing wall component and the sensing wall component encloses the sensing compartment.