A wearable air purifier

Abstract

A wearable air purifier is disclosed. The wearable air purifier comprises headgear for wearing on a wearer’s head, comprising a speaker housing 107 to be supported by the headgear over a wearer’s ear,

Description

Background of the Disclosure Exposure to air pollution such as pollutant gases or airborne particulates presents a risk 5 of harm to human health. An approach to reducing a person’s exposure to air pollution is to use a wearable air purifier to discharge filtered air towards a wearer’s face. Summary of the Disclosure The invention is defined according to the claims. LD A first aspect of the present disclosure provides a wearable air purifier, comprising: headgear for wearing on a wearer’s head, comprising a speaker housing to be supported by the headgear over a wearer’s ear, a speaker located in the speaker housing, the speaker housing comprising a protruding portion to accommodate at least part of the speaker, a fan assembly operable to generate a filtered airflow, wherein the fan assembly is releasably attachable to the speaker housing, and the fan assembly comprises an intruding portion to accommodate the protruding portion of the speaker housing when the fan assembly is attached to the speaker housing. 20 The headgear thus forms headphones, which may be used for audio playback. The fan assembly is reversibly attachable and detachable by the wearer from the headphones. The wearer may attach the fan assembly to the headgear when the provision of filtered airflow by the fan assembly is desired, and detach the fan assembly from the headgear when the airflow is not desired. The headgear may thus be used without the fan assembly attached, 25 and thus without the additional mass and bulk of the fan assembly. This may be useful as the wearer may desire to wear the headgear, i.e., the headphones, without the fan assembly in scenarios where the filtered airflow is not desired, such as in environments with low levels of air pollution. Whereas in environments with high levels of air pollution the wearer may desire to also receive the filtered airflow to reduce their exposure to the air 30 pollution. The headgear and components thereof may thus have dual functionality, which may desirably reduce a perceived need for the wearer to have separate air purifying and non-air purifying headgears, i.e., separate air purifying and non-air purifying headphones. The protruding portion of the speaker housing cooperates with the intruding portion of 5 the fan assembly to function as a locating feature. This may desirably aid correct positioning of the fan assembly relative to the headgear during attachment of the fan assembly by the wearer. Correct positioning of the fan assembly relative to the headgear during attachment may be particularly complicated in a scenario where the wearer attaches the fan assembly to the headgear in use, whilst the headgear is worn on the 10 wearer’s head, in which case the speaker housing may be outside of the wearer’s field of view. 15 Forming the male locating feature of the headgear by the protruding portion of the speaker housing has the advantage that the protruding portion is dual functional. In addition to acting as a male locating feature, the protruding portion is usable to accommodate at least a part of the speaker. Thus, the volume of the protruding portion is efficiently used, which may thereby desirably allow a reduction in overall size of the headgear compared, for example, to an alternative scenario in which the male locating feature does not accommodate the speaker. 20 The protruding portion may contact the intruding portion when the fan assembly is attached to the speaker housing. The contact between the protruding portion and the intruding portion may desirably 25 provide support to the fan assembly, to thereby reduce unwanted movement of the fan assembly relative to the headgear in use. In particular, the contact may act to retain the fan assembly to the headgear, and so inhibit inadvertent detachment of the fan assembly from the headgear in use. 30 The protruding portion may contact the intruding portion about a full circumference of the protruding portion when the fan assembly is attached to the speaker housing. The contact between the full circumference of the protruding portion and the intruding portion may desirably provide support to the fan assembly in all the directions of the plane through the circumference of the protruding portion. Thus, unwanted movement of the 5 fan assembly relative to the headgear in use may desirably be reduced. In particular, the contact may act to retain the fan assembly to the headgear, and so inhibit inadvertent detachment of the fan assembly from the headgear in use. The protruding portion may narrow progressively with protrusion. 10 This narrowing of the protruding portion may desirably ease its location in the intruding portion during attachment of the fan assembly to the headgear. Thus, attachment of the fan assembly to the headgear by the wearer may be simplified. The protruding portion could, for example, be convex in shape. 15 The intruding portion may narrow progressively with intrusion. This narrowing of the intruding portion may desirably ease locating of the protruding portion therein during attachment of the fan assembly to the headgear. Thus, attachment 20 of the fan assembly to the headgear by the wearer may be simplified. The intruding portion could, for example, be concave in shape. The protruding portion may be frustoconical. 25 The inclined circumferential surface of the frustoconical-shaped protruding portion may desirably ease location of the protruding portion in the intruding portion during attachment of the fan assembly to the headgear. Moreover, the flat end surface of the frustoconical form may desirably provide a stable stop to the insertion of the protruding portion into the intruding portion during attachment of the fan assembly. This may 30 desirably facilitate tactile feedback indicating to the wearer proper insertion of the protruding portion into the intruding portion during attachment of the fan assembly, and act to rotate the fan assembly to correct any misorientation of the fan assembly relative to the headgear. The speaker housing and the fan assembly may define respective mating surfaces, the 5 mating surfaces are configured to contact when the fan assembly is attached to the speaker housing, and the mating surfaces have cooperating forms. This contact between the cooperating mating surfaces may desirably provide support to the fan assembly, to thereby reduce unwanted movement of the fan assembly relative to 10 the headgear in use. In particular, the contact may act to retain the fan assembly to the LD 20 headgear, and so inhibit inadvertent detachment of the fan assembly from the headgear in use. For example, the mating surfaces could extend about at least part of the circumference of the protruding portion and the intruding portion respectively, e.g., about at least half of the circumference thereof. The mating surfaces may extend about a full circumference of the protruding portion and the intruding portion respectively. The fan assembly may thus be supported about the full circumference of the protruding portion, which may desirably provide a stable attachment of the fan assembly to the headgear. The contact between the cooperating mating surfaces may desirably provide support to the fan assembly, to thereby reduce unwanted movement of the fan assembly relative to the headgear in use. In particular, the contact may act to retain the fan assembly to the headgear, and so inhibit inadvertent detachment of the fan assembly from the 25 headgear in use. The mating surfaces may be flat. The flat contact surfaces may desirably provide a stable mating between the fan assembly 30 and the headgear, thereby reducing unwanted movement of the fan assembly relative to the headgear in use. Moreover, the flat mating surfaces may desirably provide a stable stop to the attachment of the fan assembly to the headgear. This may desirably facilitate tactile feedback indicating to the wearer proper attachment of the fan assembly to the headgear. The speaker housing and the fan assembly may comprise cooperating coupling parts of a 5 releasable coupling for releasably attaching the fan assembly to the speaker housing, and the coupling parts may be aligned with the mating surfaces. The retaining force applied by the coupling is thus coincident with the mating surfaces. Accordingly, the fan assembly may be stably attached to the headgear, thereby reducing 10 unwanted movement of the fan assembly relative to the headgear in use. The speaker may be accommodated concentrically in the protruding portion. The concentric location of the speaker in the protruding portion may result in the centre of mass of the speaker being concentric with the protruding portion. Further, the concentric location of the speaker may result in a relatively uniform distance between the speaker and the portion of the speaker housing that defines the protruding portion about the full circumference of the speaker. Accordingly, desirable audio performance characteristics may be achieved. 20 The wearable air purifier may comprise a battery and a conductor assembly to conduct electrical power from the battery to the fan assembly, wherein the battery is mounted to the headgear, and the conductor assembly comprises a releasable conductive coupler to facilitate releasable conductive coupling of the fan assembly to the battery. 25 In other words, the battery for powering the fan assembly may be mounted directly to the headgear instead of being integrated with the fan assembly, and a breakable electrical coupling is provided to the fan assembly, the breakable coupling allowing the releasable attachment of the fan assembly to the headgear. Mounting the battery to the headgear, instead of to the fan assembly, may desirably result in the mass of the battery being brought closer to a centre of gravity of the wearer’s head. Thereby wearer comfort may be improved. Whereas, the releasable conductive coupler accommodates the releasable attachment of the fan assembly to the headgear. The conductor assembly could directly conductively couple the battery to the fan assembly, or could conductively couple the battery indirectly to the fan assembly, for example, via a fan controller mounted to the 5 headgear. The releasable conductive coupler may comprise cooperating conductive contact, and the conductive contacts are located on the mating surfaces. 10 Locating the conductive contacts on the mating surfaces may desirably ensure a reliable conductive connection between the contacts, and thus reliable supply of electrical power to the fan assembly. This may be particularly so when the coupling parts are aligned with the mating surfaces. 15 The wearable air purifier may comprise a nozzle attachable to the fan assembly to receive airflow generated by the fan assembly and discharge the airflow towards the wearer’s face. The nozzle may thus function to carry airflow from the fan assembly closer to the wearer’s 20 face, e.g., closer to the nose / mouth region of the wearer’s face. Thus, the fan assembly may be attached to the headgear at a location relatively remote from the wearer’s face, for example, at the side, top, or rear of the wearer’s head, thereby avoiding obstructing the wearer’s face, e.g., obstructing the wearer’s vision. Whereas, notwithstanding that the fan assembly may be relatively remote from the wearer’s face, the filtered airflow may 25 still be provided relatively directly to the wearer’s nose and / or mouth via the nozzle, thereby reducing dilution of the filtered airflow by unfiltered ambient air prior to inhalation. The nozzle may, for example, be arranged to extend from the fan assembly in front of the wearer’s face, to thereby duct airflow from the fan assembly to the front of the wearer’s face, e.g., to the wearer’s lower nasal and mouth region. According to a second aspect of the present disclosure, there is provided a wearable air purifier, comprising: headgear for wearing on a wearer’s head, comprising a speaker housing to be supported by the headgear over a wearer’s ear, a speaker located in the speaker housing, a fan assembly operable to generate a filtered airflow, wherein the fan 5 assembly is releasably attachable to the speaker housing by way of a magnet coupling. The headgear thus forms headphones, which may be used for audio playback. The fan assembly is reversibly attachable and detachable by the wearer from the headphones. The wearer may attach the fan assembly to the headgear when the provision of filtered airflow 10 by the fan assembly is desired, and detach the fan assembly from the headgear when the LD airflow is not desired. The headgear may thus be used without the fan assembly attached, and thus without the additional mass and bulk of the fan assembly. This may be useful as the wearer may desire to wear the headgear, i.e., the headphones, without the fan assembly in scenarios where the filtered airflow is not desired, such as in environments with low levels of air pollution. Whereas in environments with high levels of air pollution the wearer may desire to also receive the filtered airflow to reduce their exposure to the air pollution. The headgear and components thereof may thus have dual functionality, which may desirably reduce a perceived need for the wearer to have separate air purifying and non-air purifying headgears, i.e., separate air purifying and non-air purifying headphones. 20 The speaker housing to be supported by the headgear over a wearer’s ear. Put another way, the wearable air purifier may comprise headgear for wearing on a wearer’s head and a speaker housing to be supported by the headgear over a wearer’s ear. The headgear may comprise a headband for supporting the speaker housing over a wearer’s ear. 25 By providing a magnet coupling as the means of releasably attaching the fan assembly to the speaker housing, the process of attaching the fan assembly to the speaker housing is greatly simplified for the wearer. For example, to attach the fan assembly to the speaker housing, the wearer may simply bring the fan assembly into close proximity with the 30 speaker housing in order to engage the magnet coupling and is not required to rotate or actuate a locking mechanism separately. Similarly, to detach the fan assembly from the speaker housing, the wearer may simply pull the fan assembly away from the speaker housing in order to disengage the magnet coupling and is not required to rotate or actuate a locking mechanism separately. 5 Further, as magnet couplings do not require direct contact in order to attach to each other, the fan assembly may attach to the speaker housing in a variety of different orientations without reducing the attachment strength of the magnet coupling. The magnet coupling may comprise: a first attachment feature provided in and / or on the 10 speaker housing; and a second attachment feature provided in and / or on the fan assembly. In other words, the magnet coupling may comprise a plurality of attachment features 15 distributed across both the fan assembly and the speaker housing. The attachments features may be realised in a number of way, which are discussed in further detail below. Due to the magnetic nature of the magnet coupling, the first and second attachment features do not require direct contact in order to attach to each other. Accordingly, the first and second attachment features may be provided within the speaker housing and the fan assembly, respectively. Alternatively, the first and second attachment features may be provided on the speaker housing and the fan assembly, respectively, for example on a 20 surface of the speaker housing and the fan assembly. The first attachment feature may comprise a speaker housing magnet. In other words, the speaker housing may comprise a magnet forming part of the magnet 25 coupling between the speaker housing and the fan assembly. The speaker housing magnet may comprise a plurality of speaker housing magnets. In other words, the speaker housing may comprise a plurality of magnets forming part of 30 the magnet coupling between the speaker housing and the fan assembly. The provision of a plurality of magnets in the speaker housing may improve the strength of the magnet coupling between the speaker housing and the fan assembly. Further, the provision of a plurality of magnets in the speaker housing may provide multiple different attachment points and / or orientations between the speaker housing and the fan assembly. In addition, the plurality of magnets may comprise a plurality of the same type of magnets or a 5 plurality of different types of magnets. The plurality of speaker housing magnets may be arranged in an annular array, and optionally wherein the speaker housing magnets are spaced from each other uniformly within the annular array. 10 LD In other words, the plurality of magnets in the speaker housing may be arranged in an annular array within, or on, the speaker housing. The annular array may be a complete annulus or a partial annulus. The annular array may be substantially annular and may comprise one or more concentric annular arrangements of magnets. The annular array may enable the airflow generating assembly to be indexed in a plurality of positions about a centre of the annular array. This may increase flexibility for a wearer by allowing the airflow generating assembly to be rotated to a number of different rotational positions relative to the headgear. 20 The speaker housing magnet may comprise one or more ring-shaped magnets. In other words, the magnet in the speaker housing may be provided in the shape of a ring. In this way, the magnet may be arranged concentrically with substantially circular features or components of the speaker housing, such as the protruding portion. 25 The second attachment feature may comprise a fan assembly ferromagnetic element. In other words, the fan assembly may include an element that a magnet provided in the speaker housing may attract. Thus, the magnet coupling may comprise a magnet-30 ferromagnetic element coupling. The first attachment feature may comprise a speaker assembly ferromagnetic element. In other words, the speaker housing may include an element that a magnet in the fan assembly may attract. Thus, the magnet coupling may comprise a magnet-ferromagnetic 5 element coupling. The second attachment feature may comprise a fan assembly magnet. In other words, the fan assembly may comprise a magnet forming part of the magnet 10 coupling between the speaker housing and the fan assembly. The fan assembly magnet may comprise a plurality of fan assembly magnets. 20 25 In other words, the fan assembly may comprise a plurality of magnets forming part of the magnet coupling between the speaker housing and the fan assembly. The provision of a plurality of magnets in the fan assembly may improve the strength of the magnet coupling between the speaker housing and the fan assembly. Further, the provision of a plurality of magnets in the fan assembly may provide multiple different attachment points and / or orientations between the speaker housing and the fan assembly. For example, four distinct rotational positions may be available for the fan assembly, with respect to the speaker housing. Optionally, the magnet coupling may be configured to allow the fan assembly to be pivotable up to an angle of 20° with respect to the speaker housing. For example, the fan assembly may be pivotable up to an angle of 12° with respect to the speaker housing. This allows the nozzle, when attached to the fan assembly, to be fixable in a range of suitable positions around or covering the mouth and / or nose of a wearer. The plurality of fan assembly magnets may be arranged in an annular array, and optionally wherein the fan assembly magnets are spaced from each other uniformly about the annular array. In other words, the plurality of magnets in the fan assembly may be arranged in an annular array within, or on, the fan assembly. The annular array may be a complete annulus or a partial annulus. The annular array may be substantially annular and may comprise one or more concentric annular arrangements of magnets. The fan assembly magnet may comprise one or more ring-shaped magnets. In other words, the magnet in the fan assembly may be provided in the shape of a ring. In this way, the magnet may be arranged concentrically with substantially circular features 10 or components of the fan assembly, such as the protruding portion. 20 25 The magnet coupling may comprise a magnet-magnet coupling where both the speaker housing and the fan assembly comprise a magnet. The magnet coupling may comprise a magnet-ferromagnetic coupling where one of the speaker housing and the fan assembly comprises a magnet and the other comprises a ferromagnetic element. The magnet coupling may comprise a mixed magnet coupling, where both the fan assembly and the speaker housing comprise both magnets and ferromagnetic elements. The magnet coupling may comprise a partially mixed magnet coupling, where one of the speaker housing and the fan assembly comprises a magnet and the other comprises both magnets and ferromagnetic elements. The speaker housing may comprise a protruding portion to accommodate at least part of the speaker and the fan assembly comprises an intruding portion to accommodate the protruding portion of the speaker housing when the fan assembly is attached to the speaker housing. The protruding portion of the speaker housing cooperates with the intruding portion of the fan assembly to function as a locating feature. This may desirably aid correct positioning of the fan assembly relative to the headgear during attachment of the fan assembly by the wearer. Correct positioning of the fan assembly relative to the headgear during attachment may be particularly complicated in a scenario where the wearer attaches the fan assembly to the headgear in use, whilst the headgear is worn on the wearer’s head, in which case the speaker housing may be outside of the wearer’s field of view. 5 F orming the male locating feature of the headgear by the protruding portion of the speaker housing has the advantage that the protruding portion is dual functional. In addition to acting as a male locating feature, the protruding portion is usable to accommodate at least a part of the speaker. Thus, the volume of the protruding portion is efficiently used, which may thereby desirably allow a reduction in overall size of the headgear compared, for 10 example, to an alternative scenario in which the male locating feature does not accommodate the speaker. 15 The protruding and intruding portions of the speaker housing and the fan assembly, respectively, may prevent the fan assembly from sheering away from the speaker housing, thereby improving the robustness of the attachment of the fan assembly to the speaker housing. The magnet coupling may be provided radially outward of an outer perimeter of the protruding and intruding portions. In other words, the magnet coupling may be provided around the locating features of the protruding and intruding portions, which may increase the stability of the attachment between the fan assembly and the speaker housing. 25 The protruding portion may contact the intruding portion when the fan assembly is attached to the speaker housing. The contact between the protruding portion and the intruding portion may desirably provide support to the fan assembly, to thereby reduce unwanted movement of the fan 30 assembly relative to the headgear in use. In particular, the contact may act to retain the fan assembly to the headgear, and so inhibit inadvertent detachment of the fan assembly from the headgear in use. The protruding portion may contact the intruding portion about a full circumference of 5 the protruding portion when the fan assembly is attached to the speaker housing. The contact between the full circumference of the protruding portion and the intruding portion may desirably provide support to the fan assembly in all the directions of the plane through the circumference of the protruding portion. Thus, unwanted movement of the 10 fan assembly relative to the headgear in use may desirably be reduced. In particular, the contact may act to retain the fan assembly to the headgear, and so inhibit inadvertent detachment of the fan assembly from the headgear in use. 15 The protruding portion may narrow progressively with protrusion. This narrowing of the protruding portion may desirably ease its location in the intruding portion during attachment of the fan assembly to the headgear. Thus, attachment of the fan assembly to the headgear by the wearer may be simplified. The protruding portion could, for example, be convex in shape. 20 The intruding portion may narrow progressively with intrusion. This narrowing of the intruding portion may desirably ease locating of the protruding portion therein during attachment of the fan assembly to the headgear. Thus, attachment 25 of the fan assembly to the headgear by the wearer may be simplified. The intruding portion could, for example, be concave in shape. The protruding portion may be frustoconical. 30 The inclined circumferential surface of the frustoconical-shaped protruding portion may desirably ease location of the protruding portion in the intruding portion during attachment of the fan assembly to the headgear. Moreover, the flat end surface of the frustoconical form may desirably provide a stable stop to the insertion of the protruding portion into the intruding portion during attachment of the fan assembly. This may desirably facilitate tactile feedback indicating to the wearer proper insertion of the 5 protruding portion into the intruding portion during attachment of the fan assembly, and act to rotate the fan assembly to correct any misorientation of the fan assembly relative to the headgear. The speaker housing and the fan assembly may define respective mating surfaces, the 10 mating surfaces are configured to contact when the fan assembly is attached to the speaker housing, and the mating surfaces have cooperating forms. 15 This contact between the cooperating mating surfaces may desirably provide support to the fan assembly, to thereby reduce unwanted movement of the fan assembly relative to the headgear in use. In particular, the contact may act to retain the fan assembly to the headgear, and so inhibit inadvertent detachment of the fan assembly from the headgear in use. For example, the mating surfaces could extend about at least part of the circumference of the protruding portion and the intruding portion respectively, e.g., about at least half of the circumference thereof. 20 The mating surfaces may extend about a full circumference of the protruding portion and the intruding portion respectively. The fan assembly may thus be supported about the full circumference of the protruding 25 portion, which may desirably provide a stable attachment of the fan assembly to the headgear. The contact between the cooperating mating surfaces may desirably provide support to the fan assembly, to thereby reduce unwanted movement of the fan assembly relative to the headgear in use. In particular, the contact may act to retain the fan assembly to the headgear, and so inhibit inadvertent detachment of the fan assembly from the 30 headgear in use. The mating surfaces may be flat. The flat contact surfaces may desirably provide a stable mating between the fan assembly and the headgear, thereby reducing unwanted movement of the fan assembly relative to 5 the headgear in use. Moreover, the flat mating surfaces may desirably provide a stable stop to the attachment of the fan assembly to the headgear. This may desirably facilitate tactile feedback indicating to the wearer proper attachment of the fan assembly to the headgear. 10 The speaker may be accommodated concentrically in the protruding portion. The concentric location of the speaker in the protruding portion may result in the centre of mass of the speaker being concentric with the protruding portion. Further, the LO concentric location of the speaker may result in a relatively uniform distance between the 15 speaker and the portion of the speaker housing that defines the protruding portion about the full circumference of the speaker. Accordingly, desirable audio performance characteristics may be achieved. CM The wearable air purifier may comprise a nozzle attachable to the fan assembly to receive 20 airflow generated by the fan assembly and discharge the airflow towards the wearer’s face. The nozzle may thus function to carry airflow from the fan assembly closer to the wearer’s face, e.g., closer to the nose / mouth region of the wearer’s face. Thus, the fan assembly 25 may be attached to the headgear at a location relatively remote from the wearer’s face, for example, at the side, top, or rear of the wearer’s head, thereby avoiding obstructing the wearer’s face, e.g., obstructing the wearer’s vision. Whereas, notwithstanding that the fan assembly may be relatively remote from the wearer’s face, the filtered airflow may still be provided relatively directly to the wearer’s nose and / or mouth via the nozzle, 30 thereby reducing dilution of the filtered airflow by unfiltered ambient air prior to inhalation. The nozzle may, for example, be arranged to extend from the fan assembly in front of the wearer’s face, to thereby duct airflow from the fan assembly to the front of the wearer’s face, e.g., to the wearer’s lower nasal and mouth region. According to an aspect of the present disclosure, there is provided a fan assembly operable 5 to generate a filtered airflow for use in a wearable air purifier comprising headgear for wearing on a wearer’s head, the wearable air purifier comprising a speaker housing to be supported by the headgear over a wearer’s ear, and wherein the fan assembly is releasably attachable to the speaker housing by way of a magnet coupling. 10 The further features and advantages of the fan assembly of the second aspect are equally applicable to and are hereby restated in respect of the fan assembly of the present aspect. 15 According to an aspect of the present disclosure, there is provided a wearable air purifier, comprising: headgear for wearing on a wearer’s head, comprising a speaker housing to be supported by the headgear over a wearer’s ear, a speaker located in the speaker housing, a fan assembly operable to generate a filtered airflow, wherein the fan assembly is releasably attachable to the speaker housing by way of a magnet coupling, wherein the magnet coupling comprises: a plurality of speaker housing magnets arranged in an array in and / or on the speaker housing; and a plurality of fan assembly magnets arranged in an 20 array in and / or on the fan assembly. The further features and advantages of the wearable air purifier of the second aspect are equally applicable to and are hereby restated in respect of the wearable air purifier of the present aspect. 25 Brief Description of the Drawings In order that the present disclosure may be more readily understood, embodiments of the disclosure will now be described, by way of example, with reference to the accompanying 30 drawings, in which: Figure lisa schematic perspective view of a wearable air purifier embodying the present disclosure; Figure 2 is a schematic front elevation view of the wearable purifier; 5 Figure 3 is a schematic partially exploded perspective view of the wearable air purifier; Figure 4 is a schematic partially exploded front elevation view of the wearable air purifier; 10 Figure 5 is a schematic front cross-sectional view of the wearable air purifier, 15 Figure 6 is a schematic partially exploded front cross-sectional view of the wearable air purifier; Figure 7 is a schematic side elevation view of the wearable air purifier; Figure 8 is a further schematic side elevation view of the wearable air purifier; Figure 9 is a schematic depiction of an alert system of the wearable air purifier; Figure 10 is a flow diagram depicting an example alert generation process performed by the alert system. Figure 11 shows a schematic front cross-sectional view of a wearable air purifier 25 according to an aspect of the present disclosure. Figure 12 shows a schematic front cross-sectional view of a fan assembly and a speaker housing according to an aspect of the present disclosure. 30 Figure 13 shows a schematic front cross-sectional view of a wearable air purifier according to an aspect of the present disclosure. Figure 14 shows a schematic front cross-sectional view of a fan assembly and a speaker housing according to an aspect of the present disclosure. 5 Figure 15 shows a perspective view of schematic perspective view of a wearable air purifier according to an aspect of the present disclosure. Figure 16 shows a perspective view of schematic perspective view of a wearable air purifier according to an aspect of the present disclosure. LD Detailed Description of the Disclosure A wearable air purifier 101, embodying aspects of the present disclosure, is shown schematically in Figures 1 and 2. As will be described in further detail herein, the wearable air purifier 101 is configured to be worn on a wearer’s head and deliver a filtered airflow towards a lower nasal and mouth region of a wearer’s face. Consequently, the wearer’s exposure to ambient air pollution may desirably be reduced. The wearable air purifier 101 comprises headgear 102 for mounting on a wearer’s head, a pair of fan assemblies 103, 104, for generating filtered airflows, and a nozzle 105 for 20 directing the airflows from the fan assemblies 103,104 towards the lower nasal and mouth region of the wearer’s face. The headgear 102 has the form of over-the-ear headphones, and comprises a headband 106 and left and right ear cups 107, 108 connected to respective ends of the headband 25 106. The headband 106 is arcuate, and is configured to overlie a top and sides of the wearer’s head in use, to thereby support the earcups 107, 108 over the wearer’s left and right ears respectively. The headband 106 is formed to resiliently hold the earcups 107, 108 against opposite sides, i.e., left and right sides respectively, of the wearer’s head, to thereby firmly retain the headgear 102 mounted on the wearer’s head. The headband 106 30 is resiliently flexible to accommodate differing distances between the ear cups, and so differing head widths. The earcups 107, 108 are pivotally mounted to the ends of headband 106, to facilitate pivoting of the ear cups 107, 108 to accommodate different head shapes. The left and right earcups 107, 108 comprise respective speaker housings for housing 5 components, such as respective speakers, as will be described in further detail with particular reference to Figure 5. The speakers in the earcups 107, 108 may thus be supported by the headgear 102 over the wearer’s ears, e.g., to facilitate use of the headgear 102 as headphones. The earcups 107, 108 comprise respective annular cushions 109, 110 for cushioning against the wearer’s head. 10 The fan assemblies 103, 104 are releasably attachable to a respective one of the earcups 107, 108, such that the headgear 102 may releasably support the fan assemblies 103, 104 at left and right sides respectively of the wearer’s head. The releasable attachment of the fan assemblies 103, 104 to the ear cups 107, 108 will be described in further detail with 15 reference to later Figures. The nozzle 105 is attachable at left and right ends 111, 112 to a respective one of the fan assemblies 103, 104 of the headgear 102. The nozzle 105 defines air inlets at the left and right ends 111, 112, to mate with respective air outlets of the fan assemblies 103, 104, to 20 thereby receive filtered airflow from the fan assemblies 103, 104 when so attached. The nozzle 105 is configured to extend from the left and right ends 111, 112 width-wise across the wearer’s face. The nozzle 105 comprises an air outlet at a central region approximately mid-way between the left and right ends 111,112, to be positioned approximately directly in front of and facing the wearer’s lower nasal and mouth region, in use. The nozzle 105 25 thus functions to duct filtered airflows from the fan assemblies 103, 104, supported at the sides of the wearer’s head, to the central outlet of the nozzle 105, and for discharging the airflows therefrom towards the lower nasal and mouth region of the wearer’s face. In use, when the fan assemblies 103, 104 are attached to the earcups 107, 108 30 respectively, the headgear 102 thereby supports the nozzle 105 in front of the wearer’s face. In particular, in result of the nozzle 105 being attached to the headgear 102, via the fan assemblies 103, 104, on opposite, left and right, sides of the wearer’s head, the nozzle 105 is well supported and less prone to unintended movement, e.g., vibration of the nozzle 105 in use. In comparison, coupling of the nozzle 105 to the headgear 102 at only one side of the wearer’s head, for example, at the left end 111 only, may result in a torque 5 being exerted on the single coupling by the mass of the nozzle, and may result in excessive undesired movement of the nozzle in use. LD 20 Like the headband 102, the nozzle 105 is configured to be flexible in a width dimension, i. e., parallel to the width dimension of the wearer’s head, so as to allow a distance between the point of coupling of the nozzle 105 to the headgear 102 to be varied. This flexibility advantageously allows the nozzle 105 also to accommodate differing distances between the fan assemblies 103, 104. This may advantageously accommodate differing distances between the ear cups 107, 108, and thus differing widths of wearers’ heads. Additionally, the flexibility of the nozzle 105 may desirably aid attachment and detachment of the fan assemblies 103, 104 to the ear cups 107, 108 respectively, as will be described in further detail with reference to later Figures. In examples, the nozzle 105 is configured to not contact the wearer’s face, such that it is supported by the headgear 102 a short distance in front of the wearer’s face. This noncontact configuration may advantageously improve wearer comfort, inasmuch that the potential for skin irritation or other discomfort caused by contact of the nozzle 105 with the wearer’s face is reduced. Referring next in particular to Figures 3 and 4, because the fan assemblies 103, 104 are releasably attachable to a respective one of the earcups 107, 108 of the headgear 102, the 25 fan assemblies 103, 104, and the nozzle 105 attached thereto, may be releasably attached and detached from the headgear 102 by the wearer. In examples, the fan assemblies 103, 104 and the nozzle 105 are configured to be attachable to and detachable from the headgear as an assembly, in which the nozzle 105 remains attached to the fan assemblies 103, 104 during attachment / detachment of the fan assemblies 103, 104 to / from the 30 headgear 102. Thus the wearer may attach the fan assemblies 103, 104 to the headgear 102 when the wearer desires the provision of filtered airflow, such as when the wearer is in an environment with relatively high levels of environmental air pollution, and the wearer may detach the fan assemblies 103, 104 from the headgear 102 when the filtered airflow 5 is not desired, such as when the wearer is in an environment with relatively low levels of environmental air pollution. The headgear 102 may thus be used in the latter scenario without the fan assemblies 103, 104 attached, and thus without the additional mass and bulk of the fan assemblies 103,104. For example, the headgear may be used by the wearer simply as headphones for audio playback. The headgear 102 and components thereof, to 10 be described in further detail with reference to later figures, may thus have dual functionality, which may desirably reduce a perceived need for the wearer to have separate air purifying and non-air purifying headphones. 15 Because the nozzle 105 attaches directly to the fan assemblies 103, 104, the fan assemblies 103, 104 and the nozzle 105 may be attached to and detached from the headgear 102 as an assembly, which may allow convenient attachment and detachment of the fan assemblies 103, 104 and nozzle 105 with respect to the headgear 102. In comparison, if the nozzle 105 were to attach to the headgear 102, for example to the earcups 107, 108, instead of directly to the fan assemblies 103, 104, the wearer may be 20 required to separately attach and detach both the nozzle 105 and the fan assemblies 103, 104 from the headgear 102, which may be relatively inconvenient for the wearer. Additionally, because the nozzle 105 attaches directly to the fan assemblies 103, 104, rather than, for example, attaching to the ear cups 107, 108 or the headgear 102 more generally, the fan assemblies 103, 104 are not required to releasably fluidly couple to the 25 ear cups 107, 108 or the headgear 102 more generally to deliver filtered airflow to flow to the nozzle 105. Indeed, in this configuration, the nozzle 105 is not required to fluidly couple to the headgear 102 to receive the filtered airflows, and thus a risk of airflow leakage between the fan assembles 103, 104 and the nozzle 105 may be reduced. 30 The nozzle 105 could be releasably attached to the fan assemblies 103, 104, for example, by magnet couplings, clips, or releasable catches. Thus, the nozzle 105 may be detachable by the wearer from the fan assemblies 103, 104, for example, to facilitate ex-situ cleaning of the nozzle 105. In other examples, nozzle 105 could be non-releasably attached to the fan assemblies 103, 104. For example, the nozzle 105 could be structurally integral with housings of the fan assemblies 103, 104. LD 20 To assist the wearer with the releasable attachment of the fan assemblies 103, 104 to the ear cups 107, 108 respectively, each of the ear cups 103, 104 is provided with a male locating feature, in the form of a protruding portion 301, and each of the ear cups is provided with a corresponding female locating feature, in the form of intruding portion 302. The protruding portion 301 of each earcup 107, 108 cooperates with the intruding portion 302 of the respective fan assembly 103, 104 to function as a locating feature. This may desirably aid correct positioning of the fan assembly 103,104 relative to the headgear 102 during attachment of the fan assemblies 103, 104 by the wearer. Each of the ear cups 107, 108 defines a mating surface 304, that is flat and generally annular and extends around the circumference of the protruding portion 301. The fan assemblies 103, 104 each similarly define a flat and generally annular mating surface 303 extending around the circumference of the intruding portion x. The mating surfaces 303, 304 of the fan assemblies 103, 104 and the ear cups 107, 108 are arranged to contact when the fan assemblies 103, 104 are attached to the respective ear cups 107, 108, to thereby stably support the fan assemblies 103, 104 relative to the headgear 102. Referring next in particular to Figures 5 and 6, in examples the fan assemblies 103, 104 are substantially like, as are the earcups 107, 108, and also the mechanism of attachment of the fan assemblies 103, 104 to the earcups 107, 108. Thus, for brevity, only fan 25 assembly 104 and right ear cup 108 will be described in detail herein, on the understanding that substantially the same teachings apply to fan assembly 103 and left ear cup 107. Nozzle 105 is omitted from Figures 5 and 6 to avoid obscuring the described features. Conductors are depicted by dashed lines. 30 Headgear 102 comprises batteries 501, 502 located in cushions of the headband 106, and conductor assembly 503 for electrically coupling the batteries 501, 502 and for electrically coupling the batteries 501, 502 to components of the ear cup 104 and the fan assembly 108. The ear cup 104 comprises speaker housing 504 attached to an end of the headband 106. 5 The speaker housing 504 is substantially hollow, and defines the protruding portion 302 and the mating surface 303. The protruding portion 301 is generally frustoconical in shape, and narrows progressively in area in the direction of protrusion. The mating surface 303 is flat and generally annular, and extends around the circumference of the protruding portion 301. A speaker 505 is located in the speaker housing 504, and is supplied with 10 electrical power by the batteries 501, 502 via the conductor assembly 503. A rear part of the speaker 505 is located within the part of the volume of the speaker housing 504 defined by the protruding portion 301. LD 20 The fan assembly 104 comprises fan housing 506 and base 507. The fan housing 506 is rotatably mechanically coupled to the base 507. Thus, the fan housing 506 may be rotated relative to the base 507. The fan housing 506 and base 507 together define intruding portion 302. The intruding portion 302 defines a generally frustoconical intrusion into the fan assembly 104, that narrows in area progressively in the direction of intrusion. Base 507 defines the mating surface 303 that is flat and generally annular, and extends around the circumference of the intruding portion 302. The fan housing 506 is hollow, and a motor driven fan 508, fan controller 509, and an air filter 510 are located therein. The motor driven fan 508 is supplied with electrical power by the batteries 501, 502 via the conductor assembly 503 and the fan controller 509. The fan housing 506 comprises inlet aperture(s) 511 and outlet aperture 512. The outlet aperture 512 is arranged to fluidly 25 couple with an inlet at the right end 112 of the nozzle 105 when the nozzle 105 is attached to the fan housing 506. The base 507 of the fan assembly 108 comprises mechanical attachment features 601 for releasably mechanically coupling to a cooperating mechanical attachment feature 602 30 mounted to the speaker housing 504, to thereby releasably mechanically couple the fan assembly 104 to the ear cup 108. The mechanical attachment features 601,602 are located on the mating surfaces 303, 304 of the base 507 of the fan assembly 104 and the speaker housing 504 respectively. The mechanical attachment features 601, 602 are selected to couple to adequately attach the fan assembly 104, and nozzle 105, to the earcup 108 in use, yet allow the wearer to releasably make and break the coupling to allow the wearer 5 to releasably attach and detach the fan assembly 104 to and from the ear cup 108. The mechanical attachment features 601, 604 could, for example, be magnet couplings, clips, releasable catches, or any other suitable releasable fastener. 20 25 The mechanical attachment features 601, 602 may be configured to allow the fan assembly 104 to attach to the earcup 108 in a rotationally static motion, i.e., such that the fan assembly 104 is not required to be rotated, in a screw action, to attach the fan assembly 104 to the ear cup 108. Thus, the wearer may attach / detach the fan assemblies 103, 104, and so the nozzle 105, to the ear cups 107, 108, without rotating the fan assemblies 103, 104, and thereby avoiding rotation of the nozzle relative to the headgear. Consequently, a risk of the nozzle 105 fouling the wearer’s face, or articles such as spectacles on the wearer’s face, may be reduced. The conductor assembly 503 comprises a releasable conductive coupling for releasably conductively coupling the fan assembly 104 to the ear cup 108. The releasable conductive coupling is formed by cooperating conductive contacts 603, 604 located on mating surfaces 303, 304 of the base 507 of the fan assembly 108 and the speaker housing 504 respectively. In examples, the conductive contact 603 of the fan assembly 104 forms a socket and the conductive contact 604 of the ear cup 108 forms a pin to be received in the socket to make the conductive coupling. The pin may be spring-loaded to maintain the conductive coupling between the ear cup 108 and fan assembly 104 notwithstanding a small degree of relative movement between the ear cup 108 and fan assembly 104. Where more than one conductive line is required, the releasable conductive coupling may comprise the appropriate number of pairs of conductive contacts. The conductor assembly 503 further comprises a rotatable conductive coupler 513, for 30 rotatably conductive coupling the conductive contact 603 mounted to the base 507 with the fan controller 509 mounted to the fan housing 506. The rotatable conductive coupler 513 thus conductively couples the fan controller 509 to the conductive contact 603 in a way that permits relative relation between the fan housing 506 and the base 507, whilst maintaining an electrical connection between the fan controller 509 and the batteries 501, 502. The rotatable conductor assembly 513 could, for example, comprise one or more 5 ribbon cables, or slip rings. Fan 508 is thus controllable by fan controller 509 to draw air in through inlets 511, via filter 510, and discharge the filtered airflow via the outlet 512 to the nozzle 105, as described previously with reference to earlier Figures. 10 Referring in particular to Figure 5, when the fan assembly 104 is attached to the ear cup 108, the protruding portion 301 of the ear cup 108 is accommodated in the intruding portion 302 of the fan assembly 104, such that the protruding portion 301 fills LO substantially the whole volume of the intruding portion 302, and the surface of the 15 protruding portion 301 contacts the surface of the intruding portion 302. In this attached condition, the mating surface 303 of the fan assembly 104 is in contact with the mating surface 304 of the ear cup 108. CM The rotation of the fan housing 506 relative to the base 507 rotation may desirably allow 20 the wearer to rotate the nozzle 105 relative to the headgear 102 when the fan assemblies 103, 104 are attached to the ear cups 107, 108, as will be described in further detail with reference to later Figures. In particular, because the fan housing 506 is rotatable relative to the base 507, this rotation of the nozzle 105 relative to the headgear 102 may be achieved despite the base 507 being rotationally static relative to the earcup 108. 25 Consequently, the mechanical fastening features 601, 602 and the conductive coupling contacts 603, 604, are not required to accommodate rotation of the base 507 relative to the ear cup 108. Rather, the mechanical fastening features 601, 602, and the conductive coupling parts 603, 604 need only accommodate static releasable attachment of the fan assembly 104 to the earcup 108. Thus, the mechanical fastening features 601, 602, and 30 the conductive coupling parts 603, 604 may be simplified. Ear cup 108 further comprises an alert system 514 located in the speaker housing 504. Alert system 514 is provided to monitor an environment condition and alert the wearer if the fan assembly 104 is detached from the earcup 108 and the monitored environmental condition is unacceptable. Thus, the wearer may be prompted to attach the fan assembly 5 104 to the headgear 102, so that the wearer may receive the filtered airflow to counter the unacceptable environmental condition. Alert system 514 comprises fan assembly sensor 515, environmental condition sensor 516, and controller 517. LD The fan assembly sensor 516 is to sense if the fan assembly 104 is attached to the ear cup 108. The fan assembly sensor 516 is located on the mating surface 304 of the speaker housing 504, and is arranged to interact with the mating surface 303 of the fan assembly 104 when the fan assembly 104 is attached to the ear cup 108. Thus, the fan assembly sensor 515 can be interrogated by the controller 517 to determine if the fan assembly 104 is attached to the ear cup 108. For example, the fan assembly sensor 515 could comprise a momentary switch arranged to be depressed by the fan assembly 104 when the fan assembly 104 is attached to the speaker housing 108. 20 The environmental condition sensor 516 is to sense an environmental condition. The environmental condition sensor is exposed to ambient air via apertures in the speaker housing 504. The environmental condition sensor could, for example, be sensitive to one or more pollutant gases in the ambient air, such as, nitrogen dioxide or another pollutant gas in ambient air, or to particulate matter, such as PM2.5 sized particulates. 25 The controller 517 is configured to interrogate the fan assembly sensor 515 to sense if the fan assembly 104 is attached to the ear cup 108, interrogate the environmental condition sensor 516 to sense the particular environmental condition of interest, and then selectively generate a wearer-perceptible alert to the wearer if the fan assembly 104 is not attached 30 to the ear cup 108 and the sensed environmental condition meets a particular criteria. For example, the controller 517 could comprise one or more predefined threshold values representing threshold environmental condition levels considered to be unacceptable to the wearer, for example, threshold pollutant gas concentration levels. In this case, if the sensed environmental condition meets, e g., equals or exceeds the threshold value, and the fan assembly 104 is not attached to the ear cup 108, the alert system may generate a 5 wearer-perceptible alert, to thereby prompt the wearer to attach the fan assembly 104 to the earcup 108. Thus, in a scenario where the wearer is wearing the headgear 102 without the fan assembly 104 attached to the headgear 102, but the environmental condition is determined 10 to meet the predefined threshold, the wearer can be alerted to the environmental condition to thereby prompt the wearer to attach the fan assembly 104 to the headgear 102, to receive filtered airflow to thereby counter the environmental condition. LD 20 Referring next in particular to Figures 7 and 8, because of the previously described rotation of the fan housing 506 relative to the base 507 of the fan assemblies 103, 104, the nozzle 105 may be rotated relative to the headgear 102 in use. This may desirably enable the nozzle position to be adjusted relative to the headgear to suit different head sizes. Further, referring in particular to the configured depicted in Figure 8, this rotation may allow the nozzle to be rotated by the wearer away from the lower nasal / mouth region to a lowered position. This lowered position may usefully allow the wearer to move the nozzle away from their mouth, which may, for example, be desirable when the wearer is conversing with another person, eating or drinking. Referring next to Figure 9, in examples, the controller 517 of alert system 514 comprises 25 input / output device 901, memory 902, processor 903, and system bus 904. The controller 517 of the alert system 514 is configured to generate the wearer-perceptible alert in dependence on whether the fan assembly 104 is attached to the headgear 102, sensed by fan assembly sensor 515, and on whether an environmental condition, sensed 30 by environmental condition sensor 516, meets a threshold. The alert system 514 could, for example, utilise the speaker 505 to generate an audible alert to the wearer. The alert system could, for example, further send a signal to the fan controller 509 to vary the rate of airflow generated by the fan 508 in dependence on the sensed environmental condition. Thus, the airflow rate generated by the fan 508 may be varied to counter the environmental conditions. 5 Input / output interface 901 is provided for connection of the fan assembly sensor 515, the environmental condition sensor 516, the batteries 501, 502, the speaker 505, and the fan controller 509. Memory 902 stores a computer program, comprising machine-readable instructions, for interrogating the fan assembly sensor 515 and the environmental 10 condition sensor 516, and for generating an alert signal and / or a signal to the fan controller 509. Memory 902 further stores one or more predefined environmental condition threshold values, representing environmental conditions considered unacceptable to the wearer. Processor 903 is configured for receiving and processing signals from the fan assembly sensor 515 and the environmental condition sensor 516, sense if the fan 15 assembly 104 is attached to the headgear, based on a signal from the fan assembly sensor 515, sense the environmental condition using the environmental condition sensor 516, determine if the sensed environmental condition meets the threshold value stored in memory 902, and subsequently generate an alert signal if the sensed environmental condition is determined to meet the threshold. The components 901 to 903 of the 20 controller are in communication via system bus 904. Referring finally to Figure 10, in examples the computer program for generating the alert and controlling the airflow rate of the fan 508, based on the signals from the fan assembly sensor 515 and / or the environmental condition sensor 516 comprises five stages. 25 At stage 1001, the computer program causes the processor 903 to initiate the alerting procedure. The initiation stage could be triggered, for example, by a wearer’s input, such as wearer pressing an ‘ON’ button connected to the input / output interface 901 of the controller 517, or by a wearer beginning to use the headgear for audio playback and thus 30 energising the speaker 505. At stage 1002, the computer program causes the processor 903 to interrogate the fan assembly sensor 515 to determine if the fan assembly 104 is attached to the ear cup 108. If the determination is that the fan assembly is attached to the ear cup 108, the process may cease, and stage 1001 may subsequently be repeated periodically. If the 5 determination is that the fan assembly is not attached to the ear up 108, the process may proceed to stage 1003. At stage 1003, the computer program causes the processor 903 to interrogate the environmental condition sensor 516 to sense the environmental condition. 10 At stage 1004, the computer program causes the processor 903 to retrieve the threshold environmental condition threshold value from memory 902, compare the environmental condition sensed at stage 1003 to the threshold value retrieved from memory 902, and determine if the sensed environmental condition meets the threshold value. If the 15 determination is that the sensed environmental condition does not meet the threshold, e.g., is less than the threshold, the process may cease, and stage 1001 may subsequently be repeated periodically. If the determination is that the environmental condition does meet the threshold, e.g., is equal to or greater than the threshold, the process may proceed to stage 1005. 20 At stage 1005 the computer program causes the processor 903 to generate an alert signal and / or a fan speed signal. Stage 1005 could, for example, involve the processor 903 outputting an alert signal to the speaker 505, via input / output device 901, to thereby cause the speaker 505 to generate an acoustic noise to alert the wearer. Stage 1005 could, for 25 example, further involve the processor 903 outputting a fan speed signal to the fan controller 509, via input / output interface 901, to thereby cause the fan controller 509 to set the airflow rate of the fan 508 to a relatively high rate, to thereby counter the environmental condition. 30 The operations of stages 1002 to 1004 could be performed in various alternative orders. For example, the operations of stage 1002 could be performed after the operations of stages 1003 and 1004, and / or the operations of stage 1004 could be performed before the operations of stage 1003, etc. Stage 1005 could involve generating one or both of the fan alert signal and the fan speed signal. 5 Wearable air purifiers 1100, 120 embodying aspects of the present disclosures, are shown schematically in Figures 11 and 13. The wearable air purifiers 1100, 1200 shown in Figures 11 and 13 share many features in common with the wearable air purifiers shown in Figures 1 to 10 and reference numerals in common have been maintained where appropriate. 10 LD 20 Indeed, the only difference between the examples in Figures 11 and 13 and the examples described in relation to Figures 1 to 10 is presence of magnet couplings 1101, 1102, 1201, 1202 between the fan assemblies and the speaker housings. Otherwise, the wearable air purifiers function as described above. Figure 11 shows an example of a wearable air purifier 1100 comprising magnet couplings 1101, 1102 connecting the fan assemblies 103, 104 to the speaker housings 107, 108 (an example fan filter 510 is shown in Figure 11 in only one ear cup 103). Figure 12 shows an enlarged view of one of the fan assemblies 103 connected to a speaker housing 107 (fan filter 510 is absent). As shown in Figure 12, the magnet coupling comprises a plurality of magnets 1110, 1130 provided in the fan assembly 103 that couple with a plurality of magnets 1120, 1140 provided in the speaker housing. It will be understood that the polarities of the magnets 25 in the fan assembly are complimentary to those in the speaker housing. The plurality of magnets is arranged so that the nozzle 105 can be angled with respect to the headgear through a range of magnetically coupled positions by rotating the fan assembly 103, 104 with respect to the speaker housing 107, 108. 30 Figure 13 shows an example of a wearable air purifier 1200 comprising magnet couplings 1201, 1202 connecting the fan assemblies 103, 104 to the speaker housings 107, 108 (an example fan filter 510 is shown in Figure 13 in only one ear cup 103). Figure 14 shows an enlarged view of one of the fan assemblies 103 connected to a speaker housing 107 (fan filter 510 is absent). 5 As shown in Figure 14, the magnet coupling comprises a ring-shaped magnets 1210 provided in the fan assembly 103 that couples with a ring-shaped magnet 1220 provided in the speaker housing. It will be understood that the polarity of the magnet in the fan assembly is complimentary to the magnet in the speaker housing. 10 Figures 15 and 16 show perspective views of the wearable air purifier 1100 with the fan assemblies removed. 15 As shown in Figure 15, the magnet coupling comprises a plurality of magnets 1120 arranged in an annular array of four magnets. A similar array of four magnets may be provided on the fan assembly. The annular array of magnets 1120 is arranged so that the nozzle 105 can be angled with respect to the headgear through a range of magnetically coupled positions by rotating the fan assembly with respect to the speaker housing 107, 108. 20 As shown in Figure 16, the magnet coupling comprises ring magnet 1220. A similar ring magnet may be provided on the fan assembly. The ring magnet 1220 is arranged so that the nozzle 105 can be angled with respect to the headgear through a range of magnetically coupled positions by rotating the fan assembly with respect to the speaker housing 107, 108. For example, four distinct rotational positions may be available for the fan assembly, 25 with respect to the speaker housing. Optionally, the magnet coupling may be configured to allow the fan assembly to be pivotable up to an angle of 20° with respect to the speaker housing. For example, the fan assembly may be pivotable up to an angle of 12° with respect to the speaker housing. This allows the nozzle, when attached to the fan assembly, to be fixable in a range of suitable positions around or covering the mouth and / or nose of 30 a wearer.

Claims

1. A wearable air purifier, comprising:5 headgear for wearing on a wearer’s head, comprising a speaker housing to besupported by the headgear over a wearer’s ear,a speaker located in the speaker housing,a fan assembly operable to generate a filtered airflow, anda nozzle attachable to the fan assembly to receive airflow generated by the fan10 assembly and discharge the airflow towards the wearer’s face, whereinthe fan assembly is releasably attachable to the speaker housing by way of a magnet coupling.15CM2.The wearable air purifier of claim 1, wherein the magnet coupling comprises: a first attachment feature provided in and / or on the speaker housing; and a second attachment feature provided in and / or on the fan assembly.

3. The wearable air purifier of claim 2, wherein the first attachment featurecomprises a speaker housing magnet.

204. The wearable air purifier of claim 3, wherein the speaker housing magnet comprises a plurality of speaker housing magnets.

5. The wearable air purifier of claim 4, wherein the plurality of speaker housing25 magnets is arranged in an annular array, and optionally wherein the speaker housing magnets are spaced from each other uniformly within the annular array.

6. The wearable air purifier of claim 3, wherein the speaker housing magnet comprises one or more ring-shaped magnets.

7. The wearable air purifier of any of claims 3 to 6, wherein the second attachmentfeature comprises a fan assembly ferromagnetic element.

8. The wearable air purifier of claim 2, wherein the first attachment feature 5 comprises a speaker assembly ferromagnetic element.

9. The wearable air purifier of any of claims 2 to 8, wherein the second attachment feature comprises a fan assembly magnet.10 10. The wearable air purifier of claim 9, wherein the fan assembly magnet comprisesa plurality of fan assembly magnets.15CM11. The wearable air purifier of claim 10, wherein the plurality of fan assembly magnets is arranged in an annular array, and optionally wherein the fan assembly magnets are spaced from each other uniformly about the annular array.

12. The wearable air purifier of claim 9, wherein the fan assembly magnet comprises one or more ring-shaped magnets.20 13. The wearable air purifier of any of claims 1 to 12, wherein the speaker housingcomprises a protruding portion to accommodate at least part of the speaker and the fan assembly comprises an intruding portion to accommodate the protruding portion of the speaker housing when the fan assembly is attached to the speaker housing.25 14. The wearable air purifier of claim 13, wherein the magnet coupling is providedradially outward of an outer perimeter of the protruding and intruding portions.

15. The wearable air purifier of any of claims 13 to 14, wherein the protruding portion contacts the intruding portion when the fan assembly is attached to the speaker housing.

16. The wearable air purifier of claim 15, wherein the protruding portion contacts the intruding portion about a full circumference of the protruding portion when the fan assembly is attached to the speaker housing.5 17. The wearable air purifier of any of claims 13 to 16, wherein the protruding portionnarrows progressively with protrusion.

18. The wearable air purifier of any of claims 13 to 17, wherein the intruding portion narrows progressively with intrusion.1019. The wearable air purifier of any of claims 13 to 18, wherein the speaker housing and the fan assembly define respective mating surfaces, the mating surfaces are configured to contact when the fan assembly is attached to the speaker housing, and the mating surfaces have cooperating forms.1520. The wearable air purifier of claim 19, wherein the mating surfaces extend about a full circumference of the protruding portion and the intruding portion respectively.

21. The wearable air purifier of claim 19 or claim 20, wherein the mating surfaces are 20 flat.

22. The wearable air purifier of any of claims 13 to 21, wherein the speaker is accommodated concentrically in the protruding portion.25 23. A fan assembly operable to generate a filtered airflow for use in a wearable airpurifier comprising headgear for wearing on a wearer’s head, the wearable air purifier comprising a speaker housing to be supported by the headgear over a wearer’s ear, and wherein the fan assembly is releasably attachable to the speaker housing by way of a magnet coupling.

24. The wearable air purifier of claim I, wherein the magnet coupling comprises:a plurality of speaker housing magnets arranged in an array in and / or on the speaker housing; anda plurality of fan assembly magnets arranged in an array in and / or on the fan assembly.21 03 25

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