CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority from and the benefit of United Kingdom patent application No. 2010358.6, filed on 6 July 2020, United Kingdom patent application No. 2014194.1, filed on 9 September 2020, and United Kingdom patent application No. 2105016.6, filed on 8 April 2021. The entire contents of these applications are incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to a new type of personal protective equipment (“PPE”) in the form of an apparatus that is a protective covering for a user’s head, as well as methods of manufacturing the apparatus.

BACKGROUND

Even after attempting to deal with the Coronavirus (COVID-19) pandemic, there are still major flaws with most items of personal protective equipment (“PPE”) that are not being addressed.

The most commonly used PPE is a face mask. These come in various options, ranging from the blueish masks used by the general public (roughly 3.0 micron filtration size) to medical grade masks used by medical professionals (e.g., FFP3 with a very small filtration size, such as 0.3 microns).

In order for these masks to be effective against airborne transmission of a pathogen, they need to fit tightly against a user’s face. This ensures that air travels through the filter, rather than bypassing it by travelling around the filter’s periphery.

Often, however, it is not possible to maintain a tight fit around the user’s face, and even if a tight fit is maintained this means that breathing through the mask quickly becomes difficult. This difficulty is exasperated for very fine filters, which are hard to breathe through and as a result have a predisposition for the mask to move away from the face. Testing has shown that even for a tight fitted FFP3 mask greater than 50% of the air fails to travel through the filter.

Unfortunately this means that the better a face mask is at filtering pathogens, the more difficult (and uncomfortable) it is to use effectively.

Face masks have an additional problem in that they remove a large proportion of facial expression, which can hinder communication. Although transparent areas have been proposed, this further reduces the working area of the filter, which in turn further constricts the user’s breathing and increases the propensity for air to leak around the periphery of the mask. Other types of PPE exist, such as face visors, but these are ineffective against airborne pathogens. If a pathogen is able to travel in the air passing around the periphery of a mask, then it will of course be able to travel around a visor.

Using a mask or visor also fails to provide protection against a user transferring a pathogen from their hands onto their face (e.g., via their eyes).

Face masks, visors and most other types of PPE are designed to be single use items, causing disposal problems when they are thrown away.

The Applicant has co-pending applications (identified above) that are aimed at solving various problems with existing PPE and other protective equipment, and has also conducted an extensive research program that builds on this. The present invention is aimed at optimising the PPE developed in this research program so that, in contrast to existing examples, the PPE of this invention is reusable, easy to use and comfortable, whilst at the same time being effective at preventing pathogenic transmission.

SUMMARY

The invention provides an apparatus that is configured to enclose a volume of air around a user’s head (referred to herein as an “interior volume” of air). The apparatus is configured to rest on top of the head, extend past the face and sides of the head and seal around the user’s neck. Air is permitted to enter and leave the interior volume during normal breathing, but only via a filter located at the top of the apparatus, as will be discussed in more detail below.

The apparatus is made up of several assemblies.

A first assembly comprises a rigid holding member and a stretchable (e.g., elastomeric) seal, wherein the seal extends from the rigid holding member and is configured to seal against the periphery of the user’s neck.

A second assembly comprises a rigid body that is configured to mate with and seal against the rigid holding member of the first assembly. The second assembly further comprises a transparent visor that is held by the rigid body and configured to reveal the user’s visage (that is, including at least the eyes, nose, and mouth and preferably the eyebrows, cheeks and chin).

The rigid body of the second assembly extends from the rigid holding member, around the sides and rear of the user’s head, and upwards to a rigid cap, which is configured to rest on top of the user’s head and carry the apparatus in use. The rigid body may be a separate piece to the rigid cap, or these may be integrally formed.

The rigid cap comprises an air inlet/outlet configured to permit air to travel into and out from the interior volume.

The apparatus further comprises a filter device that is connected to and sits on top of the rigid cap, and comprises a filter configured to collect, neutralise, kill (or ‘inactivate’) pathogens travelling in an airflow through it. The apparatus is configured such that air travelling between the interior volume and the external environment during normal breathing has to travel via the air inlet/outlet, and pass through the filter.

The apparatus described above provides a new type of personal protective equipment (“PPE”) that achieves the advantages of multiple existing types of PPE whilst being comfortable and easy to use.

More specifically, the apparatus prevents a user from infecting themselves, by preventing them from touching their face (e.g., with contaminated fingers) and infecting themselves with pathogens, for example via their eyes, nose, mouth, lips or ears. The invention differs from protective hoods (for example) due to the rigidity of the main constituent parts (i.e., the holding member, body and cap), which forms a hard shell around the user’s head, which allows them to easily breathe whilst wearing the apparatus (avoiding the so-called ‘paper bag’ effect).

The visor reveals the user’s visage to other people nearby allowing the user’s facial expressions to be visible whilst protecting the user from contact with airborne pathogens exhaled from infected persons nearby.

The apparatus provides filtered air to the user without the need for valves, fans or batteries, or any moving parts within the airflow path.

The apparatus also protects other persons in the vicinity of the user, by filtering out viruses and airborne pathogens in the exhaled breath of the user if they are themselves infectious.

Providing an unrestricted airflow path (e.g., no temporary blockages or constrictions) from the interior volume to the filter via the air inlet/outlet, and then from the filter to the external environment avoids the use of complex, separate inlet and outlet valves. This is achieved using the single (combined) air inlet/outlet that is fluidly connected to the filter device.

Accordingly, the apparatus is a complete, unified system of PPE that obviates the need for the use of multiple, less effective (or even ineffective) forms of PPE commonly used. For example, the PPE of the invention not only achieves the aims of a face mask and visor combination, but goes further to improve the effectiveness considerably and in a more comfortable manner.

The design and construction of the apparatus is such that the internal volume space surrounding the user’s head is kept small and practical. Extending the apparatus to only the neck (and, e.g., keeping the holding member adjacent to the jawline) enables the build-up of CO2 to be kept as low as possible, and particularly below the usually accepted specification maximum of 1%. The apparatus is configured to be carried by the rigid member on top of the head, so that it is spaced apart from and does not rest on the shoulders in use.

The apparatus may be further refined in various embodiments that will be described in more detail below.

Looking first to the filter device, this may comprise a filter cartridge that plugs into the air inlet/outlet to fix it in position. Various types of pathogenic filter are known and the invention is not limited to one particular type. The cartridge may comprise at least one filter sheet that sits in the airflow path between the interior volume and the surrounding environment.

Each filter sheet may be completely sealed around its periphery, so as to maximise the filter area within the airflow path and ensure that all air travelling between the interior volume and the surrounding environment passes through the filter. This is in contrast, for example, to the unreliable sealing against a user’s face of conventional PPE.

Each filter sheet may be held substantially flat between its sealed edges, that is without any undulations, pleats or folded edges (but encompassing a single flat or curved surface), which has been found to improve the sealing and airflow characteristics.

In an optimised arrangement, the cartridge is a box having sides formed by a quadrilateral housing, wherein two filter sheets are superimposed but separated from each other, so as to form the top and bottom surfaces of the box with a cavity therebetween. The box may be slightly bent so as to follow a contour of the rigid cap when fixed in position. Each filter sheet is sealed around its periphery to upper and lower rims of the housing, and held substantially flat between its sealed edges. The housing comprises an opening in one of the sides that is configured to mate with the air inlet/outlet to fluidly connect the cavity with the interior volume. This arrangement provides a very large filter area to minimise the pressure drop across the filter when the user breathes (since all air has to pass through the filter when doing so).

Accordingly, upon plugging the cartridge into the air inlet/outlet, and upon an inhalation of a user’s breath, air is drawn from the external environment, through each of the filter sheets and into the cavity therebetween, and then flows from the cavity into the interior volume via the air inlet/outlet. Similarly, upon exhalation of a user’s breath, air travels from the interior volume into the cavity (via the air inlet/outlet), then flows from the cavity through the filter sheets to the external environment.

The filter device may comprise a cover that connects to the rigid cap, and sits over and wraps around the cartridge to conceal the filter. This prevents a user (or anyone else) from accessing the filter in use, which is in contrast to conventional face masks that are completely open to the user, who frequently needs to touch the mask to adjust its fit. The cover can permit air to travel into and out from the filter device when connected to the rigid cap, for example through a long, narrow slit formed between the cover and rigid cap when they are connected to each other.

Moving now to the first assembly, the rigid holding member thereof may comprise a substantially ovoid ring that is configured to extend around a user’s chin, wherein each side of the ovoid preferably follows a respective jawline of the user and meets again at the back of their head when fitted, for example roughly at the level of the user’s ears. Accordingly, the rigid holding member may be angled downwards from the back of the head to the front, which means that the apparatus can accommodate various head movements and avoid touching the user’s shoulders in use.

The rigid holding member is preferably a fixed ovoid ring that is configured to pass over the user’s head into position. In other embodiments the rigid holding member may comprise moving parts such as a hinge, so instead of passing over the user’s head it can split (e.g., at the front, with the hinge at the rear) to pass around the user’s neck into position.

The neck seal may be manufactured from a stretchable (e.g., elastomeric) material, such as rubber, which could also be an ovoid ring that is configured to extend in a concentric manner from the rigid holding member (e.g., an upper rim of the seal clamped within a groove thereof), to the peripheral seal against the user’s neck (e.g., a lower rim of the seal that is sealed around the user’s neck).

It has been found that pressure differences caused by a user breathing in and out through the filter are small enough so that a hermetic (e.g., vacuum resistant) seal is not required. Thus, the neck seal may be any resilient material (e.g., fabric, rubber, etc.) that urges the lower rim against the user’s neck to seal around its periphery.

As mentioned above the neck seal may be configured to split if a hinged holding member is used. Alternatively, where a one-piece assembly is used the neck seal should be sufficiently resilient to allow it to be stretched over the user’s head during assembly, then seal against their neck once in position.

Moving now to the second assembly, the transparent visor may be a continuous sheet of transparent material that is held taut against the rigid body. As such the visor may not substantially move when the user breathes (avoiding the so- called ‘paper bag’ effect). The visor may wrap around at least 160 degrees of the periphery of the apparatus (i.e. , around the front and sides of the head).

The visor may be sealed around its periphery to opposing sealing surfaces, and the apparatus may comprise a spring-loaded means (e.g., including a resilient member) configured to urge the visor against the sealing surfaces. This ensures that the visor material is always pulled into engagement with the sealing surfaces, for example if it is slightly displaced in use. Such an arrangement will also take account of tolerances in the parts of the apparatus that hold and seal the visor in position (as well as the visor itself). This helps provide the visor as a replaceable part, so that it can be easily changed if scratched or damaged in use. That is, the spring loading means ensures that a new visor can be pulled into proper engagement with the opposing sealing surfaces, even if it differs very slightly in shape or stiffness from a previous visor.

In one embodiment, the second assembly may comprise a retainer configured to hold the visor in position in a relatively loose arrangement, such as projections that extend into apertures. The retainer may comprise resilient members on each side that cooperate with cams on the rigid body (or vice-versa), wherein rotation of each cam compresses the respective resilient member and pulls the retainer closer to the rigid body, which in turn presses the visor against the opposing sealing surfaces.

The second assembly may be configured to mate with and seal against the first assembly as described above. To achieve this, the rigid holding member of the first assembly may comprise a sealing surface around its upper periphery, and the second assembly may comprise a sealing surface around its lower periphery that is configured to mate with the sealing surface of the holding member. A resilient/compressible seal member may be placed between the sealing surfaces to ensure an airtight seal between the two assemblies.

The apparatus may comprise a spring loaded means (e.g., a resilient clip) that is configured to press and hold the second assembly against the first assembly, and compress the seal member placed between the sealing surfaces to enclose the interior volume around the user’s head.

The second assembly (e.g., rigid member and visor) comprises a rigid, substantially upright cylindrical portion that extends from the ovoid ring of the first assembly. Since the periphery of the ovoid ring is intended to extend out beyond the periphery of the user’s head, this portion of the second assembly is configured to extend past the user’s face and sides of the head to the rigid cap. The rigid cap initially follows the contour of the cylindrical portion, then extends over the user’s head to rest on top of it as aforesaid.

Generally, the apparatus is intended to be portable, and could weigh less than about 1 kg, which can be easily carried on the top of a user’s head. The constituent parts combine to provide a hard, rigid shell that fits around the head and can be picked up and fitted into position without deforming or flapping/fluttering/etc. (unlike, for example, a flexible hood).

The apparatus is designed for multiple (even lifetime) use, by comprising parts that can be repeatedly sterilised, in particular the main rigid elements. The apparatus may include disposable or replaceable items, but these could be limited to the visor and filters, which could be exchanged easily as described elsewhere herein. The invention is intended to reduce the huge volume of single use PPE sent to landfill every day, as well as the cost of single use PPE (by, e.g., healthcare workers, dentists, masseurs, hairdressers, nail technicians etc.).

The apparatus is designed for long-term use and can be tailored to specific users, as opposed to the ‘one-size-fits-all’ approach to conventional PPE.

For example, the construction of the apparatus means that each separate part can be customised for different head sizes. In contrast, a face mask is typically one size, and even if it were to be made larger, you would simply get a larger mask. By providing an apparatus having a separate neck piece, holding member, rigid body and (potentially) cap, these separate parts could each be dimensioned individually. This provides a much more customisable and tailored unit. The neck seal could be dimensioned according to a user’s neck size, or be provided with different sizes similar to different shirt collar sizes. Different size neck seals could be provided for the same size rigid holding member, etc.

The size/dimensions of the various parts could be tailored such that, for a given head size, the CO2 within the interior volume remains below the accepted specification maximum of 1% during normal breathing.

The apparatus may then be constructed using the individually dimensioned parts to create the customised and tailored unit.

Accordingly, this creates a new type of PPE that is personal to the user, which is distinct from one-size-fits-all, disposable PPE flooding the market.

Following on from this, the apparatus may be customised in other ways. For example, the apparatus may comprise one or more electronic accessories, for example a battery for powering a number of (optional) electrically powered components. The apparatus may comprise a battery-driven cooling fan, which may be located in the rigid cap adjacent to the user’s forehead. This fan could be configured to blow air around the interior volume, rather than draw air into or out from it (which is not necessary using the disclosed invention). Other add-ons such as LEDs could be located in the cap.

The invention also extends to a method of manufacturing an apparatus as described above. The method may comprise constructing the rigid holding member, rigid body and rigid cap, as well as the stretchable seal and visor, then fitting the stretchable seal to the rigid holding member so that it extends from the rigid holding member and is configured to seal against the periphery of the user’s neck as aforesaid, and fitting the visor to the rigid body so that it is held by the rigid body and configured to reveal the user’s visage as aforesaid. The method may be used to construct the individual and tailored unit described above, and include the step of constructing the individually dimensioned parts.

A particularly useful technique for manufacturing the rigid constituent parts of the apparatus (including the rigid holding member, rigid body and rigid cap) is additive manufacturing, otherwise known as 3D printing. This is the construction of a three-dimensional object from a computer-aided design (“CAD”) model or other suitable type of digital 3D model.

Accordingly, in accordance with an aspect of the invention there is provided a system comprising an additive manufacturing device configured to construct one or more (or all) of the rigid constituent parts of the apparatus described above, including one or more (or all) of the rigid holding member, rigid body and rigid cap.

The method of manufacturing may comprise the step of additively manufacturing (e.g., 3D printing) one or more (or all) of the rigid constituent parts of the apparatus, including one or more (or all) of the rigid holding member, rigid body and rigid cap.

The invention also extends to a computer program comprising instructions which, when the program is executed by a computer of an additive manufacturing device (e.g., as described above), cause the additive manufacturing device to additively manufacture one or more (or all) of the rigid constituent parts of the apparatus, including one or more (or all) of the rigid holding member, rigid body and rigid cap.

The invention also extends to a computer readable storage medium comprising instructions which, when executed by a computer of an additive manufacturing device (e.g., as described above), cause the additive manufacturing device to additively manufacture one or more (or all) of the rigid constituent parts of the apparatus, including one or more (or all) of the rigid holding member, rigid body and rigid cap.

The invention also extends to a computer program comprising instructions which, when the program is executed by a computer of an additive manufacturing device (e.g., as described above), cause the computer to carry out the method steps described above that involve constructing one or more (or all) of the rigid constituent parts of the apparatus, including one or more (or all) of the rigid holding member, rigid body and rigid cap.

The invention also extends to a computer readable storage medium comprising instructions which, when executed by a computer of an additive manufacturing device (e.g., as described above), cause the computer to carry out the method steps described above that involve constructing one or more (or all) of the rigid constituent parts of the apparatus, including one or more (or all) of the rigid holding member, rigid body and rigid cap.

The instructions in any of the aspects described above including a computer program or computer readable storage medium may include a CAD model or other digital 3D printable model.

The 3D printable model may be created via 3D scanning (using a suitable 3D scanner), or by a plain digital camera and suitable photogrammetry software. The 3D scanning may encompass a process of collecting digital data on the shape and appearance of the rigid constituent parts of the apparatus, including the rigid holding member, rigid body and rigid cap, and creating a digital model based on it.

The CAD model or other digital 3D printable model may be provided in a stereolithography file format (“STL”) or Additive Manufacturing File format (“AMF”).

Once completed, the instructions including the CAD model or other digital 3D printable model may be processed to convert the model into a series of thin layers and produce a G-code file containing instructions tailored to a specific type of 3D printer (e.g., FDM printers). This G-code file can then be printed with 3D printing client software (which loads the G-code, and uses it to instruct the 3D printer during the 3D printing process).

The additive manufacturing or 3D printing described above can include a variety of processes in which material is deposited, joined or solidified under computer control to create a three-dimensional object, with material being added together (such as plastics, liquids or powder grains being fused together), typically layer by layer.

BRIEF DESCRIPTION OF THE DRAWINGS

Various embodiments of the invention will now be described, by way of example only, and with reference to the accompanying drawings in which:

Fig. 1 shows an apparatus according to an embodiment;

Fig. 2 show a side view of the apparatus of Fig. 1 ;

Fig. 3 shows a partly-assembled view of the apparatus of Fig. 1, and without a filter device to illustrate the air inlet/outlet in the top of the apparatus;

Fig. 4 shows the same view as Fig. 3, but with a filter cartridge plugged into the apparatus;

Figs. 5A-5F show the assembly of the filter cartridge shown in Fig. 4;

Fig. 6 shows a cross-sectional view of the apparatus of Fig. 1;

Figs. 7A-7C show the visor assembly for the apparatus of Fig. 1 ; and

Figs. 8 and 8A show cross-sectional views illustrating the clip assembly for connecting the two assemblies that form the apparatus.

DETAILED DESCRIPTION

Fig. 1 shows a perspective view of an apparatus 10 for covering the head 2 of a person.

The apparatus 10 is configured to rest on top of the head 2, extend past the face and sides of the head 2 and seal around the user’s neck 4 to provide an interior volume 1 of air. Air is permitted to enter and leave the interior volume 1 during normal breathing, but only via a filter device 100 located at the top of the apparatus, as will be described in more detail below.

The apparatus 10 comprises a lower, rigid holding member 20 that is configured to extend around the user’s chin, wherein each side of the holding member 20 follows the jawline of the user and meets at the back of their head 2, roughly at the level of the user’s earlobes. This is shown more clearly in Fig. 2, from which it can be seen that the rigid holding member 20 is angled downwards from the back of the head to the front.

The apparatus 10 further comprises a rigid body 40 that is configured to mate with and seal against the rigid holding member 20. The rigid body 40 extends upwards from the rigid holding member 20, including past the face, sides and back of the user’s head 1, to a rigid cap 80.

The apparatus 10 further comprises a visor 60 that extends around the periphery of the user’s head 2 (e.g., at least 160 degrees of the periphery of the apparatus 10), as well as having a large vertical extension (e.g., at least about 15 cm at the front of the apparatus 10) that reveals the user’s entire visage. As shown in Fig. 2, the apparatus 10 further comprises a stretchable (e.g., elastomeric) seal 30, wherein the seal 30 extends from the rigid holding member 20 and is configured to seal against the periphery of the user’s neck 4.

The holding member 20, body 40 and cap 80 form a hard shell that, along with the visor 60 and seal 30 fits around the head to provide the interior volume 1. Using a hard shell means that the apparatus does not deform (e.g., flap or flutter) and advantageously retains its shape when fitted and moved around, in contrast to, e.g., PPE flexible hoods that are often used to cover a person’s head.

Fig. 3 shows the apparatus 10 without the filter device 100, in order to illustrate an air inlet/outlet 82 that is located in the rigid cap 80. This air inlet/outlet 82 provides the only path for air to enter and exit the interior volume 1 during normal breathing. As is illustrated in Fig. 3, air may enter the interior volume 1 in the direction of arrow 85, and then travel down into the interior volume 1 adjacent the user’s forehead.

As discussed above the apparatus 10 is configured to collect, neutralise, kill (or “inactivate”) pathogens travelling in an airflow into the interior volume 1.

Fig. 4 shows the apparatus with a filter cartridge 102 that plugs into the air inlet/outlet 82 of the rigid cap 80 and comprises a pair of filter sheets 104 (only one of which can be seen in Fig. 4) that sit in the airflow path between the interior volume 1 and the surrounding environment.

The cartridge 102 is box-shaped and comprises a quadrilateral housing 110, wherein two filter sheets 104 are superimposed but separated from each other, so as to form the top and bottom surfaces of the box with a cavity 150 therebetween.

Referring to Figs. 4 and 5A-F, the box is slightly bent so as to follow a contour of the rigid cap 80 when fixed in position. Each filter sheet 104 is sealed around its periphery to upper and lower rims of the housing 110. The housing 110 comprises an opening 114 at the front thereof that is configured to mate with the air inlet/outlet 82 to fluidly connect the cavity with the interior volume 1.

Accordingly, upon plugging the cartridge 102 into the air inlet/outlet 82, and upon an inhalation of a user’s breath, air is drawn from the external environment, through each of the filter sheets 104 and into the cavity 150 therebetween, and then flows from the cavity 150 into the interior volume 1 via the air inlet/outlet 82. Similarly, upon exhalation of a user’s breath, air travels from the interior volume 1 into the cavity 150 via the air inlet/outlet 82, then flows from the cavity 150 through each of the filter sheets 104 to the external environment.

Referring as well to Fig. 1, the filter device 100 comprise a cover 130 that connects to the rigid cap 80, and sits over and wraps around the cartridge 110 to conceal the filter sheets 104. This prevents a user (or anyone else) from accessing the filter sheets 104 in use. The cover 130 permits air to travel into and surround the cartridge 110 through a long, narrow slit 132 that is formed between its lower periphery and the surface of the cap 80. Figs. 5A-5F show the construction of the cartridge 102 of the filter device 110 in more detail.

The housing 110 of the cartridge 102 is shown in Fig. 5A and comprises four walls/sides 112a-d, with an opening 114 provided in one of the sides 112a that is configured to mate with (i.e., plug into) the air inlet/outlet 82, which may be referred to as the ‘front’ of the cartridge 102. A seal 116 is provided around the opening 114 and configured to seal against an opposing surface of the air inlet/outlet 82, so as to fluidly seal the opening 114 and air inlet/outlet 82.

Two sides 112b, 112d of the housing 110 extend from the front initially in a parallel fashion, then flare out towards the rear of the cartridge 102, so that that the side 112c of the housing 110 at the rear thereof is wider than the side 112a at the front. This particular shape advantageously maximises filter area and enables an existing face mask filter to be fitted into the cartridge 102. However, the shape is not essential, for example the housing 110 could be square, rectangular, etc.

A pair of seals 118 are located on upper and lower rims of the housing 110 and extend around its periphery. A plurality of ribs 120 are provided that extend lengthwise from the rear wall 112c towards and into the opening 114. The ribs 120 are provided for structural support also to guide air along channels between the ribs 120 and into/out from the opening 114.

Fig. 5B shows the housing 110 with a filter sheet 104 placed on top of the upper seal 118 and rim. The filter sheet 104 is configured to follow the contour of the upper rim and seal around its periphery, so that air entering the cavity 150 from above has to pass through a large proportion of the upper filter sheet 104.

Fig. 5C shows the housing 110 with an insert 125 that is configured to clip into the housing 110 to retain the filter sheet 104 and press its edges against the upper seal 118 so as to ensure a good sealing contact. The insert 125 comprises a number of ribs 126 for structural support and to help retain the filter sheet 104. The insert 125 is configured to slightly deform to allow it to fit into housing 110, and is retained by a number of clips 128 located around its periphery.

Figs. 5D-5F show substantially the same arrangement for the lower filter sheet 104, which is placed on top of the lower seal 118 and fits into the housing 110 in a similar manner. The lower filter sheet 104 is also retained by an insert 125, and is sealed so that air entering the cavity 150 from below has to pass through a large proportion of the lower filter sheet 104.

Once the upper and lower filter sheets 104 are held in sealing engagement using the inserts 125, the filter cartridge 102 is complete and ready to be plugged into the air inlet/outlet 82 as described above and shown in Fig. 4.

Fig. 6 shows a cross section through the apparatus 10, including the filter cartridge 102 plugged into the air inlet/outlet 82.

Here the filter device 100 further comprises the cover 130 that connects to the rigid cap 80, and sits over and wraps around the cartridge 110 to conceal the filter sheets 104. The cover 130 is configured to attach to the rigid cap 80 using suitable clips 132 located at the front and rear of the cover 130, although any suitable attachment mechanism may be used.

Fig. 6 also shows the rigid holding member 20 in cross-section. This comprises a substantially ovoid ring that is configured to extend around the user’s chin, wherein each side of the ovoid follows a respective jawline of the user and meets again at the back of their head when fitted, for example roughly at the level of the user’s earlobes. As can be seen in both Figs. 1 and 5, the rigid holding member 20 is angled downwards from the back of the head to the front, which means that the apparatus can accommodate various head movements since it avoids contact with the shoulders and back of the user.

In the illustrated embodiment the rigid holding member 20 is a fixed ovoid ring, but in other embodiments the rigid holding member 20 may comprise movable parts such as a hinge. As such, instead of passing over the user’s head it could split (e.g., at the front, with the hinge at the rear) to pass around the user’s neck into position.

An upper portion of the neck seal 30 is clamped/sandwiched between internal and external ring pieces 20a, 20b of the rigid holding member 20, and sits within a groove thereof to retain it in position. Any suitable retaining mechanism may be used, although the neck seal 30 should be retained so that it seals against the rigid holding member 20 and air cannot escape from the interior volume 1 around an upper rim thereof.

The neck seal 30 extends from the upper portion down to a lower rim 32, where the seal 30 is configured to press against the user’s neck to enclose the interior volume 1. The seal 30 as illustrated is made of a stretchable (e.g., elastomeric) material, such as rubber, which extends in a concentric manner from the upper rim to the lower rim 32.

It has been found that the pressure differences caused by a user breathing in and out through the filter are small enough so that a hermetic (e.g., vacuum resistant) seal is not required. Thus, the neck seal 30 may be any material (e.g., resilient fabric, rubber, etc.) that urges the lower portion against the user’s neck to seal around its periphery.

The neck seal 30 and rigid holding member 20 combine to form a first assembly of the apparatus 10.

Still referring to Fig. 6, the visor 60 is a continuous sheet of transparent material that is held taut against the rigid body 40 using a retainer 62 and spring loaded mechanism 70.

The retainer 62 and mechanism 70 are configured to pull the visor 60 taut and ensure a good seal throughout the life of the visor 60, as well as upon replacing the visor 60 with a new one. The mechanism 70 also ensures that visor 60 does not deform when the user breathes (avoiding the so-called ‘paper bag’ effect). The visor wraps around about 180 degrees of the periphery of the apparatus 10 (i.e. , around the front and sides of the user’s head 1). Fig. 7 A shows the retainer 62 in isolation, which is of a shape that is configured to extend around the periphery of the visor 60.

The retainer 62 comprises a plurality of protrusions 64 that are configured to extend into corresponding apertures 66 on the visor 60 (Fig. 7B). The protrusions 64 are spaced from an inner rim 63 of the retainer 62 to leave an area 65 between the protrusions 64 and the inner rim 63. This area 65 is configured to engage sealing members that press into the visor 60 when placed in position, as will be described in more detail below.

The retainer 62 further comprises racetrack-shaped apertures 68 that are configured to receive locating pins 67 on the rigid body 40.

Fig. 7 A further illustrates part of the spring loaded mechanism 70, namely a resilient wire 72 (e.g., piano wire) on each side. The wire 72 is held taut within a housing 74 by any suitable means, and extends through an aperture 76 that may be positioned between the racetrack-shaped locating apertures 68.

Fig. 7B shows the visor 60 attached to the retainer 62 by pressing the visor into the retainer so that the protrusions 64 extend through the apertures 66. At this stage the visor 60 is fitted to the retainer 62 relatively loosely, so that although the visor 60 is held in proper position by the engagement of the protrusions 64/apertures 66, it is not held taut.

Referring briefly back to Fig. 6, this shows the visor 60, retainer 62 and seals 69 in position. The seals 69 oppose the area 65 between the protrusions 64 and the inner rim 63, and extend around the entire periphery of the visor 60.

Fig. 7C shows the retainer 62 with visor 60 mounted onto the rigid cap 40, by locating the retainer 62 over the cap 40 using the locating pins 67. The racetrack shaped apertures 68 permit slight movements of the retainer 62 (and visor 60) in the direction of arrow 79.

Fig. 7C shows the mechanism 70 for pulling the visor 60 taut and to ensure a good seal around its periphery. It will be appreciated that an identical arrangement is provided on the opposite side of the retainer 62. The rigid cap 40 comprises cams 74 that are configured to abut each respective wire 72 when the retainer 62 and visor 60 are fitted onto the cap 40 as shown. Rotation of each cam 74 urges its respective resilient wire 72 in the direction of arrow 79, which pulls the retainer 62 and visor 60 towards the user’s face. This in turn causes the visor 60 to be urged tightly against the opposing seals 69 around its periphery as aforesaid.

A cover plate 78 may be placed over each mechanism 70 to enclose and protect it in use, wherein the cover plates 78 may clip into place, for example using pins 77. The geometry of the cover plates 78 may match that of the retainer 62, so that it sits flush with the front surface thereof when clipped into place.

Thus, the visor 60 is sealed around its periphery to the opposing seals 69.

The mechanism 70 ensures that the visor material is always pulled into engagement with the seals 69. This will also take account of tolerances in the parts of the apparatus 10 that hold and seal the visor 60 in position (as well as the visor 60 itself). For example, the visor 60 may be replaceable, so that it can be easily changed if scratched or damaged in use.

The rigid body 40 (with visor 60 etc.), rigid cap 80 and filter device 100 combine to form a second assembly of the apparatus 10, which second assembly is configured to mate with and seal against the first assembly. When mated together, the rigid body 40 and visor 60 extend from the rigid holding member 20 as an ovoid cylinder, around at least the sides and rear of the user’s head 1 , and upwards to the rigid cap 80 that is configured to rest on top of the user’s head 1. The rigid body 40 may be a separate piece to the rigid cap 80, or these may be integrally formed.

Figs. 8 and 8A show a cross-section of the rear of the apparatus 10, showing in more detail the engagement of the first and second assemblies.

The rigid holding member 20 of the first assembly comprises a sealing surface 22 around its upper periphery, and the rigid body 40 of the second assembly comprises a sealing surface 42 around its lower periphery that is configured to oppose the sealing surface 22 of the holding member 20. A resilient/compressible seal member 24 is placed between the sealing surfaces 22, 24.

The apparatus 10 comprises a clip arrangement 28 configured to hold the second assembly against the first assembly, and compress the seal member 24 between the sealing surfaces 22, 24 to enclose the interior volume. The clip arrangement 28 comprises a resilient tab 29 that is configured to ride over and then clip onto a rigid hook 27 that is connected to the rigid holding member 20. Upon doing so, the sealing surfaces 22, 42 are urged towards each other and the seal member 24 is compressed to ensure an airtight seal between the two assemblies.

Fig. 8 shows a hook 28a that is connected to the front of the rigid body 40, and configured to latch onto a surface of the rigid holding member 20. This is provided so that the second assembly can be located in the correct position before operating the clip arrangement 28 at the rear of the apparatus 10. That is, a user can provisionally latch the hook 28a onto the front of the apparatus 10, and then seal the first and second assemblies together using the clip arrangement 28 as described above.

The apparatus 10 may comprise additional electronics, for example a microphone 90 adjacent the user’s mouth, speakers 92 adjacent the user’s ears and a fan 94 adjacent the user’s forehead. The fan 94 is configured to blow air around the interior volume. The fan 94 is not required to draw air in through the filter device, which is achieved purely by the user breathing. The apparatus 10 could comprise lights (e.g., LEDs) 96 that are directed forwards, to help aid the user’s vision in poor visibility or technical environments. If desired, the apparatus 10 may comprise buttons 98 for operating any of the electronics.

Although the present invention has been described with reference to various embodiments, it will be understood by those skilled in the art that various changes in form and detail may be made without departing from the scope of the invention as set forth in the accompanying claims.