GB2594100A

GB2594100A - A protective mask

Info

Publication number: GB2594100A
Application number: GB2007057.9A
Authority: GB
Inventors: Regan Basil; Ledwith Shane; Ganley Sean; Ganley Declan
Original assignee: Individual
Current assignee: Individual
Priority date: 2020-04-17
Filing date: 2020-05-13
Publication date: 2021-10-20
Also published as: GB202005576D0; GB202007057D0

Abstract

A protective mask 10, for example suitable for use as a powered air-purifying respirator, comprises a body portion 11 having a frame 12 and a transparent visor 13, forming an enclosure 14 around at least a portion of the face of a user; an air inlet 16, an air movement means 15 (for example a centrifugal fan, figure 7a) in fluid communication with the inlet, and an outlet. Preferably the mask is sealed against the face and comprises air guidance vanes (19, 23 figure 3; 39, figures 10-12) in order to direct the air laterally across the sides of the face (41, figure 5) which via the Coanda effect will also induce airflow over the wearers nose and mouth (42, figure 5). The mask may further comprise a filtered exhaust vent 18 towards the chin. The inlet filter may be thin with a large surface area to reduce resistance to flow, and may be retained in place by a mesh cover 36. The filter or visor may be specifically arranged acoustically to reduce the impediment of sound such as speech from the wearer, for example from a medical practitioner to a patient. Also claimed is a method of manufacture.

Description

A Protective Mask

Field of the Invention

This invention relates to a protective mask and in particular to a compact and energy efficient protective mask.

Background of the invention

Fundamentally, a respirator filters air provided to a user and in its most basic form comprises a passive disposable face filter. A respirator of this type can come with or without an exhaust valve. In the latter case, the exhaust air is not filtered and resultantly others are not protected from the user's exhalation. Such products are cheap and can be effective if properly fitted but they are far from ideal in many circumstances. Users tend to find breathing more difficult and when used for an extended period, they pick up moisture from exhaled breath, becoming uncomfortable and ineffective. In practical use, boundary leakage is common and even slight leaks can reduce effectiveness by as much as 65%. Other examples of currently available respirators take the form of reusable passive respirators. These products incorporate a more comfortable and effective seal and can include eye protection. The filters of these products are disposable and are changed at a frequency dependant on usage.

In recent years, products have been developed to overcome some of the aforementioned disadvantages. The most common type of such a device is a Powered Air Purifying Respirator (PAPR). There are two main classes of PAPR device, namely sealed and loose fitting devices. The former must be fit tested and come in different sizes. The latter do not always come in different sizes and with a loose fit; a fit test is not required. A significantly sized battery, filter and fan system is worn on a belt and the filtered air is transferred through a hose to the headpiece. There are several key advantages to this type of system. Firstly, since the head piece is slightly pressurised, minor leaks or a loose fit do not constitute a significant risk. The typical disposable face filter can easily leak between 0 and 20% of inhaled air whereas the corresponding figure for a loose fitting PAPR is 4%, and 2% in the case of a tight fit. The user has a constant supply of fresh air so there is no breathing difficulty and issues related to heat, sweat, and visor fogging are eliminated. Known PAPR systems are typically quite cumbersome and somewhat isolating for the user. Such systems would generally be considered inappropriate for someone operating outside of an industrial or medical environment. Systems are available where all components are located in a headpiece. Again, even these headpiece only devices are typically cumbersome. Until recently, Standards required that PAPR systems continue to function after the filters ingest quite an amount of foreign matter such as dust or sand. In addition, these devices often use filters which can handle a very broad range of contaminants. These factors greatly increase the power demand and fan size.

It is desirable to provide a protective mask which comprises the benefits of a powered air purifying respirator but is less cumbersome and requires reduced power input.

Summary of the Invention

According to the invention there is provided a protective mask comprising: a body portion comprising a frame and a transparent visor, the body portion being configured to, in use, form an enclosure around at least a portion of the face of a user; at least one air inlet; at least one air movement means in fluid communication with the at least one air inlet; a filter means; and at least one air outlet; wherein the at least one air movement means is configured to move air from exterior of the protective mask, through the at least one air inlet and filter means, to the enclosure.

Optionally, the enclosure is an at least partially sealable enclosure.

Advantageously, the protective mask adopts a compact shape and form and exhibits a low power 15 demand.

Ideally, the protective mask further comprises an air guide arrangement configured to guide air from the at least one air movement means towards the nose and/or mouth of a user.

Advantageously, transfer of large amounts of air directly towards the eyes is avoided.

Preferably, relative to the airflow direction caused by the air movement means, the filter means is positionable in front of the air inlet means such that air entering the air inlet means is filtered by the filter means.

Alternatively, the filter means is locatable between the air inlet means and the air movement means.

Preferably, the air guide arrangement comprises an exhaust guide disposed at least partially around the air movement means such that air exhausted from the air movement means is guided by the 30 exhaust guide towards the nose and mouth of a user.

Optionally, the exhaust guide is a double exhaust guide comprising two exhaust outlets, the two exhaust outlets being configured to guide air from the air movement means in two different directions.

Ideally, the air guide arrangement comprises one or more guide vanes configured to guide air from the at least one air movement means, or exhaust guide thereof, towards the nose and mouth of a user.

Preferably, the air guide arrangement guides air from the air movement means generally towards the lateral inner side surfaces of the protective mask.

Advantageously, air is directed initially generally away from the eyes of a user and encouraged to 5 take a route to the nose and mouth of a user which is not substantially via the eyes.

Ideally, at least some portion of the inner surfaces of the protective mask are configured to encourage airflow towards the nose and/or mouth of a user.

Preferably, at least some portion of the inner surfaces of the protective mask are configured to utilise the Coanda effect to encourage airflow to remain attached to said inner surfaces such that said airflow may be accurately channelled to the nose and mouth region.

Preferably, the at least one air movement means comprises at least one fan.

Optionally he at least one air movement means comprises two fans.

Preferably, the at least one fan comprises an air intake direction and an air output direction.

Preferably, air output direction of the at least one fan is generally perpendicular to the air intake direction thereof.

Advantageously, the at least one fan can intake air from externally of the protective mask from a frontal direction, and output air into the at least partially sealable enclosure.

Ideally, the at least one fan is a centrifugal fan.

Advantageously, when compared to an axial fan, centrifugal fans require less space, are forgiving in relation to intake and outtake conditions, and are better suited to situations with high pressure 30 requirements such as drawing air through a filter.

Preferably, the at least one air movement means is an electrically powered at least one air movement means, and preferably is powered by a 5 Volts DC power supply.

Alternatively, the electrically powered movement means is powered by a 12 Volt DC power supply.

Advantageously, the protective mask has a low power demand, and any battery utilised to power the protective mask may be charged using existing USB charging infrastructure.

Preferably, the filter is a low resistance filter.

Ideally, the filter means is a thin low resistance filter means.

Preferably the filter means comprises a thickness of 4mm or less.

Ideally, the filter means comprises a thickness of between 1mm and 4mm.

Preferably, the filter means comprises a large surface area.

Ideally, the filter means comprises a surface area of approximately 72cm2.

Alternatively, the filter means comprises a surface area of between approximately 72cm2and 100cm2.

Advantageously, the thickness of the filter means and surface area thereof act to lower pressure resistance/minimise pressure loss and thus makes it easier for the air movement means to draw air through the filter means. Further advantageously, the surface air speed of the filter means is reduced which improves the efficiency with which the filter means can act to filter undesirable material.

Preferably, the filter means is configured to filter bio-hazards and/or biological agents.

Ideally, the filter means is not configured to filter odour, chemical contaminants, or any other foreign bodies or substances not defined as bio-hazards and/or biological agents.

Advantageously, the specific target of the filter means and the fact that it is not intended to filter a 25 wide spectrum of items outside of bio-hazards and/or biological agents permits the filter means to comprise a reduced thickness and thus reduced pressure resistance.

Ideally, in use, the external circumference of the body portion which is closest the users face and defines an opening into the at least partially sealable enclosure for a users face does not extend 30 beyond the forehead, outer cheeks, and lower jaw of a user.

Advantageously, the protective mask may adopt a compact form.

Preferably, the at least one air outlet is locatable on a lower portion of the protective mask, proximal 35 the jaw of a user when the protective mask is in use.

Alternatively, or in conjunction, the at least one air outlet is locatable below a users chin when the protective mask is in use.

Ideally, the at least one air outlet comprises at least one outlet filter.

Alternatively, the at least one air outlet may be an unfiltered outlet.

Preferably, the body portion comprises an upper end proximal a users forehead when in use, a lower end proximal a users jaw when in use, and a lateral dimension which extends generally across a 5 users face from proximal one ear to another when in use.

Ideally, the at least one air inlet, filter means, and at least one air movement means are disposed centrally in relation to the lateral dimension of the body portion, and locatable proximal the upper end thereof generally above the eyes of a user when in use.

Preferably, in use, the filter means may extend from a position above the eyes of a user towards the crown of the head of a user.

Ideally, at least a portion of the filter is locatable on a section of the body portion which extends 15 obliquely partially across the top of a users head.

Preferably, the air guide arrangement is configured to guide air from the centrally disposed at least one air movement means, generally along an interior surface of the body portion, and towards each lateral side of the body portion.

Ideally, the filter means is configured to at least partially permit sound to travel therethrough.

Ideally, one or more of the material stiffness, mass, material density, material sound damping properties, shape, or thickness, of one or more portions of the protective mask, are optimised such 25 that sound in the frequency range of human speech may be transmitted, in use, between the interior of the protective mask and the exterior thereof Alternatively, or in combination, the protective mask may be provided with an interior microphone and operably connected exterior speaker such that the user may efficiently communicate whilst 30 wearing the protective mask.

Further alternatively, or in combination, the protective mask may comprise a speech diaphragm configured to aid transmission of speech between the interior of the protective mask and the exterior thereof.

Preferably, a rim of sealing material is provided around an inner edge of the protective mask.

Ideally, an attachment means such as an adjustable strap for attachment of the protective mask to a user.

Preferably, the filter means comprises an air permeable filter mesh which is configured to releasably retain the filter means.

Ideally, the visors configured to provide a large field of vision.

Preferably, the visor is configured to maintain a significantly open and unobstructed view from the exterior.

Advantageously, others can fully see the wearer's face and facial expressions.

According to a second aspect of the invention there is provided a method of manufacturing a protective mask comprising the steps of: forming a body portion comprising a frame and a transparent visor, the body portion being configured to, in use, form an enclosure around at least a portion of the face of a user; providing at least one air inlet; attaching at least one air movement means in fluid communication with the at least one air inlet; installing a filter means; and providing at least one air outlet; wherein the at least one air movement means is configured to move air from exterior of the protective mask, through the at least one air inlet and filter means, to the enclosure.

Brief description of the drawings

An embodiment of the invention is now described by way of example and with reference to the accompanying drawings in which: Figure 1 is a perspective view of a protective mask; Figure 2 is a front view of the protective mask of Figure 1; Figure 3 is an exploded perspective view of the protective mask of Figure 1; Figure 4 is a side view of the protective mask of Figure 1; Figure 5 is a front view of the protective mask of Figure 1 showing indications of airflow paths within the protective mask; Figure 6 is a perspective view of a protective mask in use showing indications of airflow direction into and out of the protective mask; Figure 7a is a perspective view of a centrifugal fan for use in a protective mask; Figure 7b is a perspective view of an axial fan; Figure 8a is a schematic view of air output from a centrifugal fan having no exhaust guide; Figure 8b is a schematic view of air output from a centrifugal fan having a dual exhaust guide, Figure 9 is a schematic view of a filter means and fan of a proactive mask showing indications of airflow therethrough; Figure 10a is a schematic view showing a splitter feature splitting the air output from a single fan; Figure 10b is a schematic view showing a splitter feature splitting the air output from two fans; Figure 10c is a schematic showing air output from a single fan having a dual exhaust; Figure lla is a front view showing a protective mask in use and indicating one potential guide 15 apparatus and resulting airflow path therein; Figure 11b is the protective mask in use of Figure 11a indicating an alternative guide apparatus and resulting airflow path therein; Figure 12 is the protective mask in use of Figure 11 a indicating areas of airflow adherence to inner surfaces of the protective mask and areas of airflow separation from inner surfaces thereof; Figure 13 is a perspective view of a protective mask comprising at least a portion of the filter and air inlet means thereof extending obliquely partially across the top of a users head; Figure 14 is a perspective view of the protective mask of Figure 13 showing upper and lower air outlet filters; and Figure 15 is a perspective view of the protective mask of Figure 13 showing loupes mounted to the 30 protective mask

Detailed Description of the drawings

The present teaching will now be described with reference to an exemplary protective mask. It will be understood that the exemplary protective mask is provided to assist in an understanding of the present teaching and are not to be construed as limiting in any fashion. Furthermore, elements or components that are described with reference to any one Figure may be interchanged with those of other Figures or other equivalent elements without departing from the spirit of the present teaching.

Turning to the drawings, Figures 1 to 3 illustrate a protective mask 10 comprising a body portion 11. The body portion 11 comprises a frame 12 and a transparent visor 13 and is configured to, in use, form an enclosure 14 around at least a portion of the face of a user. The enclosure is an at least partially sealable enclosure 14, and may be a fully sealable enclosure 14. At least one fan 15 in fluid communication with at least one air inlet 16 is provided, and a filter 17 is disposed in front of the air inlet 16 and the at least one fan 23. It should be understood that embodiments are envisaged wherein the filter 17 may be disposed between the air inlet 16 and the fan 15. The at least one fan 15 will herein be referred to as a singular fan 15. However it should be understood that more than one fan 15 may be utilised in any herein described embodiments. At least one air outlet 18 is provided to permit exit of air form the protective mask 10. The fan 15 is configured to move air from exterior of the protective mask, through the at least one air inlet 16 and filter 17, to the at least partially sealable enclosure 14 such that a wearer may breathe suitably filtered air. The protective mask 10 adopts a compact shape and form and as such can be easily transported and stored in a briefcase, handbag, backpack, or the like. Moreover, the protective mask 10 exhibits a low power demand, in particular in comparison to existing powered air purifying respirators (PAPR's). In general, the protective mask 10 acts to draw air across the filter 17 and then distribute the air across the lower face inside the least partially sealable enclosure 14, the enclosure 14 providing full protection to eyes, nose and mouth. In addition to providing filtered air, the movement of air affected by the protective mask will also prevent condensation from a user's breath, and mitigate issues related to user sweating.

In preferred embodiments, the fan 15 is a centrifugal fan 15 such as that shown in Figure 7a. Fan choice largely depends on a balance between required airflow and the pressure against which that airflow must be achieved. Axial fans, such as that shown in Figure 7b for comparison, lend themselves more towards applications where flow rate is relatively greater than pressure, whereas centrifugal fans are preferable when working against relatively high pressures. Axial fan blades use aerofoil profiles and therefore are sensitive to inflow and outflow conditions. If the air pattern over the aerofoil of an axial fan is spoiled, it simply looses its lift. Hence, they often require significant space before and after the fan to ensure an unspoiled airflow. In contrast, a centrifugal fan 15 effectively pushes air and it thus very forgiving of less than ideal inlet and outlet conditions, it can therefore operate efficiently in a relatively small space which is important in relation to the protective mask 10 of the present invention as the compact nature of the design is of importance. A further advantage accrues from the configuration of the centrifugal fan 15. A centrifugal fan 15 exhausts air in a direction perpendicular to the inlet direction, again see figure 7a, and this is very convenient in applications where such an air path is sought. The use of a centrifugal fan 15 therefore affords clear advantages for the present invention. Drawing air through a filter 17 is a relatively high pressure application and the centrifugal fan 15 can be squeezed into a relatively small space without greatly affecting performance in such applications. In addition, the airflow directions of the centrifugal fan 15 facilitate the targeted air paths such as those shown in Figures 9 and 10. The centrifugal fan 15 is disposed such that the axis of rotation thereof maybe thought of as extending in a direction generally forward of a users forehead when in use. This permits the centrifugal fan to draw in air from a first direction 43 generally in front of the protective mask 10, and exhaust the drawn air in a second direction 45, generally perpendicular to the first direction, and generally into the at least partially sealed enclosure 14. The orientation of the centrifugal fan 15 can be best seen in Figure 9. The fan is an electrically powered fan having an electrical motor 46, and preferably is powered by a 5 Volts DC power supply. Some configurations, as will be later discussed, require a higher power input. Such configurations utilise, for example, a 12 Volt DC power supply.

The protective mask 10 further comprises an air guide arrangement 19 configured to guide air from the fan 15 towards the nose and/or mouth of a user. Advantageously, transfer of large amounts of air directly towards the eyes may be avoided thus avoiding inefficient use of the incoming filtered air, and impairment of vision or discomfort. The air guide arrangement 19 comprises an exhaust guide 20 disposed around the fan 15 such that air exhausted from the fan 15 is guided by the exhaust guide 20 on a desired airflow path. The exhaust guide 20 in preferable embodiments is an exhaust housing 20. The exhaust housing 20 may also be a double exhaust housing 21 comprising two exhaust outlets 22, as can be seen in Figure 8b, which exhausts air from the fan 15 in two directions. Preferably, the air guide arrangement 19 comprises one or more guide vanes 23 configured to guide air from the fan 15, or exhaust housing 20 thereof. The guide vanes 23 may be in addition to or in place of the exhaust housing 20. The exhaust housing 20 and/or the guide vanes 23 act to guide air from the fan 15 on a desired airflow path. Where a double exhaust housing 21 is used, as is illustrated in Figure 10c, the airflow is drawn through the filter by the fan 15 and directed perpendicularly towards the lateral inner side surfaces of the protective mask. As it is undesirable to have the air blow directly over the user's eyes, the double exhaust housing 21 effectively splits the airflow in at least partially opposing directions towards the lateral inner side surfaces 24. This can also be achieved using at least a portion of the guide vane 23 which is shaped and dimensioned to act as a splitter 39 as can be seen in Figure 10a. The splitter 39 may also be utilised in a two fan arrangement as shown in figure 10b, wherein the airflow from each fan 15 is directed by the splitter 39 to opposing lateral inside surfaces 24 of the protective mask 10. In preferred embodiments, the guide vane 23 and splitter 39 is used to direct the airflow rather than the double exhaust housing 21. Once the airflow reaches the lateral inner side surfaces 24, it will turn in a generally downwards direction towards a lower end 25 of the protective mask. The lateral inside surfaces 24 of the mask 10 may themselves be shaped and/or dimensioned to achieve this turn of airflow. Alternatively a further guide vane or an extended splitter 26 may be used as can be seen in Figure 11b. The extended splitter 26 may comprise a downwardly depending curved end portion 27 which encourages a downward turn in the air flow travelling along the splitter and splitter extension. The airflow 41 travelling along the top 28 and lateral inner side surfaces 24 of the protective mask 10 will stay attached to said surfaces as a result of the Coanda effect. Any tendency for the air to separate away from said surfaces will cause a reduction in pressure at the respective surface, thereby causing the air to stay attached to that surface. In effect, the air naturally runs along the top 28 and lateral inner side surfaces 24 of the protective mask 10. Exploitation of the Coanda effect is not only an efficient way to channel air to the desired location, it also requires no external power to achieve said effect and thus helps the protective mask 10 minimise power demand. Moreover, utilising the Coanda effect also lessens the demand placed on the fan 15 to transport air to the desired region of the protective mask, thus facilitating the use of a smaller fan. Once the airspeed begins to drop, and in particular at a mid-portion 40 of the protective mask 10 whereat the cheekbone area of a user interferes with the airflow, it is much more likely that the airflow 42 will detach and diffuse across the mouth and nose region, aiding in effective airflow delivery to the intended target. In this way, the airflow is not forced over the eyes which is not desirable but rather is directed to where it is needed, at the nose and mouth, in a manner which is both effective and efficient in terms of energy consumption of the protective mask 10. If fogging is problematic, it is possible to employ the same Coanda effect as discussed above to divert a small fraction of the air along the visor 13 surface. In this way, the users eyes are not subjected to the airstream but a thin film of air helps keep the visor 13 clear. This could, for example, be achieved by placing small apertures in the guide vane 23 such that a small amount of air from the fan 15 travels directly through the guide vane 23 to the surface of the visor 13. If enhanced airflow is required, two fans can be used in parallel as discussed above and as shown in Figure 10b, each feeding a different half of the protective mask 10.

The filter 17 is a thin low resistance filter. The filter 17 comprises a thickness of 4mm or less. In the preferred embodiment the filter 17 comprises a thickness of between 1mm and 4mm. The filter 17 also has a relatively large surface area given the size of the overall protective mask 10. In preferred embodiments, the filter 17 comprises a surface area of approximately 72 cm2. In some cases, the filter 17 may comprise a surface area of approximately 100 cm2. Advantageously, the thickness of the filter and surface area thereof act to lower pressure resistance and minimise pressure loss and thus makes it easier for the fan 15 to draw air through the filter 17, and further allows passive filtering for the user at a low back pressure. Further advantageously, the surface air speed of the filter 17 is reduced due to the relatively large surface area, which improves the efficiency with which the filter 17 can act to filter undesirable material. The filter 17 is configured to filter bio-hazards and/or biological agents. Importantly, the filter is not configured to filter odour, chemical contaminants or the like; it is specifically targeted towards bio-hazards and/or biological agents. Advantageously the specific target of the filter, and the fact that it is not intended to filter a wide spectrum of items outside of biohazards and/or biological agents, permits the filter to comprise the thin nature as described above and thus reduced pressure resistance. The filter is sealably connected to the body portion 11 such that air travelling to the fan 15 via the air inlet 16 must pass through the filter 17. The sealably connected filter 17 may be releasably sealably connected such that the filter 17 may be removed and replaced if required. In preferred embodiments, the filter 17 sealed in place by clipping a meshed plastic piece 36 over the filter 17 which acts to clamp-seal the perimeter of the filter 17, as is best seen in Figure 3. At least in part due to the thin nature of the filter 17, a small fan 15 may be utilised which draws relatively little power. Resultantly, a small, low voltage battery 34 can provide adequate run time for the protective mask 10. Thus, the combination of thin filter 17 and small fan 15 allow a compact design where the fan 15 and filter 17 are conveniently and inconspicuously located in front of the forehead of a user. The battery 34 can be located in the same region or alternatively at the back of the head on a mounting strap 29. If significantly longer run time is required, a larger battery (not shown) can be mounted on an upper arm strap or on a waist belt (not shown). A further advantage of the lower power demand is that the system can be run on 5V DC which is compatible with standard USB power hardware. Thus, a vast range of compatible battery designs and associated recharging hardware are compatible. For example, rather than carrying a charger, an office worker could recharge the device from his/her computer. In use, the external circumference of the body portion 11 does not extend beyond the forehead, outer cheeks, and lower jaw of a user. Thus the device provides full face protection but maintains a small form.

The at least one air outlet 18 is locatable on a lower portion of the protective mask, proximal the jaw of a user when the mask is in use. The at least one air outlet 18 in preferable embodiments comprises a plurality of air outlets 18. The air outlets 18 may be locatable generally at the lower end of the protective mask 10, and in some embodiments may be located on a portion 35 of the mask below the chin of a user when in use, as can be seen in Figure 4. The air outlets may also be located on the visor 13, as can be seen in Figures Ito 3. The air outlets 18 may be filtered or unfiltered air outlets 18, the filtered outlets comprising an outlet filter 37 and outlet filter retaining mesh 38 which acts to attach the outlet filter in a similar manner to the mesh 36 of the inlet filter 17. Some embodiments may comprise both filtered and unfiltered outlets 18. In embodiments intended for medical applications, the outlets 18 will generally be filtered outlets 18, whereby any exhaled air is filtered providing protection to patients in addition to the user. In such medical use cases, the protective mask 10 is also likely fully sealed to the face of a user and a user fit test could be carried out for each person who uses the protective mask 10. Air is drawn through the filter 17, spread across the lower facial area and then exhausted through the filtered air outletsl 8. Battery life for medical use embodiments may also target 8 to 12 hours such that they may provide enough power for a typical medical shift with some to spare. Should the full seal leak, the pressure resistance to the fan 15 will reduce and increased airflow will result, at least a portion 44 of which airflow vents at the leak. In this way the positive pressure design prevents foreign matter entering through a leak. Should the battery 34 die or fan 15 fail, the mask, in embodiments wherein the air outlets 18 are filtered outlets, will still function as a passive system while the user exits a hazardous area. In any case, an alarm is provided which alerts the user to low battery power, fan failure, and/or any other system failures which may compromise effective functioning of the protective mask. The total filter 17 area is relatively large as and the filter 17 relatively thin as discussed above. Resultantly, the breathing back pressure is not unacceptable to the user. Other embodiments not intended for medical use may not form a full seal around the face of a user. In this case, safe function of the mask depends on continuous pressure and the air outlets 18 may not be filtered. The advantage of this embodiment is that exact fit is not as critical. Figure 14 illustrates an embodiment having filtered upper and lower outlets 18. In such an embodiment, an upper outlet filter 51 may be provided along with one or more lower outlet filters 52. When lower outlet filters 52 are required, these may be located under and/or up the sides of the jaw adjacent portion of the protective mask, or alternatively/in combination air intended to be passed through the outlets 18 can be ducted to the upper filters 52 located over the ears. The ducting could be embedded in the sealing material running up the side of the face. In this way, the single piece integrity of the device is maintained.

The body portion 11 comprises an upper end 30 proximal a users forehead when in use, a lower end 40 31 proximal a users jaw when in use, and a lateral dimension which extends generally across a users face from a side 32 proximal one ear to a side 33 proximal another ear when in use. The air inlet 16, filter 17, and fan 15 are disposed centrally in relation to the lateral dimension of the body portion 11, generally above the eyes and in the centre of a user's forehead when in use. The location of the fan 15 and filter 17 generally in front of the forehead of a user is optimal to create the airflow path as described above. However, there is limited space in this particular area of the protective mask 10, in particular is maintaining an aesthetically pleasing low profile device is desirable. The small centrifugal fan 15 is therefore advantageous in accommodating and operating within the small area available. In addition, as described above, the filter 17 has a relatively large surface area. This large filter 17 surface area is achieved by extending the filter 17 over a large portion of the upper frontal region of the protective mask 10. The filter 17 may also extend towards the crown of the head of a user on a section 50 of the body portion 11 which extends obliquely partially across the top of a users head. In this way the surface area of the filter 17 may be maximised without unduly increasing the overall size of the protective mask 10. As is best seen in Figures 13-15, the filter 17 may comprise two portions, one forward facing portion 17a, and one portion on the section 50 of the body portion 11 which extends obliquely partially across the top of a users head. The two portions 17a, 17b of the filter are in fluid connection with the fan 15 such that the fan may draw air through both filter portions 17a, 17b. Again, this arrangement maximises the surface area of the filter 17 which leads to the advantages as discussed above.

A further advantage of the relatively thin filter 17 is that speech can travel through it with ease.

Should the air outlets 18 be filtered, the filter utilised may be thinner than the inlet filter 17 and as such enhance further the transfer of sound/speech from internally of the protective mask 10. A significant drawback in using prior art full face masks is the detrimental effect they can have on communication. The specific filter thickness of the present invention provides significant improvement upon the sound transmissibility of prior art systems. In the prior art, sometimes a diaphragm is used to overcome this drawback, and sometimes a microphone and speaker are employed. The protective mask 10 of the present invention could use either of these to further enhance communication, however the relatively thin filter 17 acts to facilitate speech without any further infrastructure which would add size, weight, power requirements, and/or cost to the device. Where a speech diaphragm is utilised, it may be moulded to the sealing material used to seal or partially seal the mask 10 to a users face. The protective mask 10 may also be acoustically optimised such that the transmissibility of speech frequencies is yet further enhanced. In this case, one or more of the material stiffness, mass, material density, material sound damping properties, shape, or material thickness of one or more portions of the protective mask 10 are optimised such that sound in the frequency range of human speech may be more easily transmitted between the interior of the protective mask 10 and the exterior thereof. The acoustic optimisation of the protective mask 10 may be facilitated by carrying out analysis which would be known to the skilled person, such as modal frequency analysis.

A rim of sealing material (not shown) is provided around an inner edge of the protective mask 10 and 40 acts to form a partial or full seal between the protective mask 10 and a users face. The sealing material may be a rubber material, or any other such seal forming material which would be well known to the skilled person. The strap 29 provided for attachment of the protective mask 10 to a user may also be an adjustable strap 29.

In medical applications, doctors may wear loupes. In any of the referenced embodiments, sufficient 5 space can be left behind the visor 11 or perhaps preferably, a visor 11 can be made which incorporates an insert 55 to accommodate standard sized loupes 54. This is best seen in Figure 14, In this way, no element of the visor 11 interferes with the loupe line of sight. As would be understood by the skilled person, there are many other ways by which the loupes 54 could be mounted in the visor and Figure 14 or the preceding description are provided for example only and are in no way to 10 be construed as limiting in relation to the loupe 54 attachment method.

To facilitate sterilisation of the mask 10, heating the whole assembly to an elevated temperature for an extended period is particularly effective. The materials, and especially the fan 15 lubricants and seals will be selected so that they are heat tolerant. The build design and material selection will be able to withstand repetitive thermal fatigue cycling. Moreover, standards in relation to ventilators require that these products be sold inside a substantial container. Any container (not shown) supplied with the present invention can be designed to also function as a heated sterilisation pod so that the user can easily self sterilise the protective mask 10. The pod could be designed to achieve sterilisation using different sterilisation methods, for example but not limited to alcohol immersion, UV sterilisation, etc. One or more surfaces of the protective mask 10 may be treated with coatings which inhibit growth of viruses and/or bacteria. This will contribute towards the overall safety of the protective mask 10.

An inbuilt pad or other such identification element (not shown) is provided for the user to write their name, thereby ensuring ownership security and reducing the risk of cross contamination caused by mistaken use of another individuals mask. This pad/element would have to be resistant to heating sterilisation temperatures and sterilisation fluids.

As touched upon above, the present invention encompasses configurations of the protective mask 10 which differ based on use case. A first, basic configuration is fully sealed around the face. Air is drawn in through the filter 17 and exits through unfiltered air outlets 18 in the sealing material below the jaw. The user is protected but others are not protected from the user. This device has a particularly low power demand and can comfortably run on 5 volts DC. In this embodiment, each user requires a fit test and multiple sizes are required to achieve the required fit. A second configuration of the protective mask 10 has a loose fit, especially under the jaw. Again, others are not protected from the user. A key advantage of this configuration is that no fit test is required and a single size may suffice. A relatively high airflow must be maintained to ensure outflow across all the unsealed areas and the resulting high power demand necessitates a higher voltage so that 5 Volts DC is no longer an option. A higher voltage of, for example, 12 Volts DC is appropriate. This configuration may also easily be incorporated into a hood or more comprehensive overall protective outfit/suit. A third configuration is fully sealed and the air outlets 18 are filtered. This requires additional power to force air through both inlet and outlet filters so again, a higher voltage power source such as a 12 Volt DC source is required. The location of the outlets and associated filters could be in the jaw/neck area of the protective mask, or the air may be vented away to filtered outlets located in the upper head region. Again, this type of configuration could be designed so that it can be easily incorporated into a more comprehensive overall protective outfit/suit All of the above referenced features contribute to providing a compact powered protective mask 10 which is a fraction of the size of existing solutions, but equally as effective. The protective mask 10 10 may also be easily adapted for both medical and general use.

The invention is not limited to the embodiment(s) described herein but can be amended or modified without departing from the scope of the present invention.

Claims

CLAIMS 1. 2. 3. 4. 7. 8.A protective mask comprising: a body portion comprising a frame and a transparent visor, the body portion being configured to, in use, form an enclosure around at least a portion of the face of a user; at least one air inlet; at least one air movement means in fluid communication with the at least one air inlet; a filter means; and at least one air outlet; wherein the at least one air movement means is configured to move air from exterior of the protective mask, through the at least one air inlet and filter means, to the enclosure.
The protective mask of claim 1, further comprising an air guide arrangement configured to guide air from the at least one air movement means towards the nose and/or mouth of a user.
The protective mask of claim 2, wherein the air guide arrangement comprises an exhaust guide disposed at least partially around the air movement means such that air exhausted from the air movement means is guided by the exhaust guide towards the nose and mouth of a user.
The protective mask of claim 2 or claim 3, wherein the air guide arrangement comprises one or more guide vanes configured to guide air from the at least one air movement means, or exhaust guide thereof, towards the nose and mouth of a user.
The protective mask of any of claims 2 to 4, wherein the air guide arrangement guides air from the air movement means generally towards the lateral inner side surfaces of the protective mask.
The protective mask of claim 5, wherein at least some portion of the inner surfaces of the protective mask are configured to encourage airflow towards the nose and/or mouth of a user, and preferably all or part of the inner surfaces of the protective mask are configured to exploit the Coanda effect to encourage airflow towards the nose and/or mouth of a user.
The protective mask of any preceding claim, wherein the at least one air movement means comprises at least one fan, and optionally two fans.
The protective mask of claim 7, wherein each of the at least one fan is a centrifugal fan.
9. The protective mask of any preceding claim, wherein the at least one air movement means is an electrically powered at least one air movement means, and preferably is powered by a 5 Volts DC or 12 Volt DC power supply.
10. The protective mask of any preceding claim, wherein the filter means is a thin low resistance filter means, and preferably comprises a thickness of 4mm or less, and preferably comprises a thickness between lmm and 4mm.
11. The protective mask of any preceding claim, wherein the filter means comprises a large surface are, and preferably a surface area of between approximately 72cm2 and 100cm2
12. The protective mask of any preceding claim, wherein the filter means is configured to filter bio-hazards and biological agents.
13. The protective mask of any preceding claim, wherein, in use, the external circumference of the body portion which is closest the users face and defines an opening into the enclosure for a users face does not extend beyond the forehead, outer cheeks, and lower jaw of a user.
14. The protective mask of any preceding claim, wherein the at least one air outlet is locatable on a lower portion of the protective mask, proximal the jaw of a user when the protective mask is in use.
15. The protective mask of any preceding claim, wherein the at least one air outlet comprises at least one outlet filter.
16. The protective mask of any preceding claim, wherein the body portion comprises an upper end proximal a users forehead when in use, a lower end proximal a users jaw when in use, and a lateral dimension which extends generally across a users face from proximal one ear to another when in use.
17. The protective mask of claim 16, wherein the at least one air inlet, filter means, and at least one air movement means are disposed centrally in relation to the lateral dimension of the body portion, and locatable proximal the upper end thereof generally above the eyes of a user when in use.
18. The protective mask of claim 16 or 17, wherein the filter means may extend from a position above the eyes of a user towards the crown of the head of a user, such that at least a portion of the filter is locatable on a section of the body portion which extends obliquely partially across the top of a users head.
19. The protective mask of claim 1701 18, when dependent on claim 2, wherein the air guide arrangement is configured to guide air from the centrally disposed at least one air movement means, generally along an interior surface of the body portion, and towards each lateral side of the body portion.
20. The protective mask of any preceding claim, wherein the filter means is configured to at least partially permit sound to travel therethrough.
21. The protective mask of any preceding claim, wherein a rim of sealing material is provided around an inner edge of the protective mask such that the enclosure is an at least partially sealable enclosure.
22. The protective mask of any preceding claim, further comprising an attachment means such as an adjustable strap for attachment of the protective mask to a user.
23. The protective mask of any preceding claim, wherein the filter means comprises an air permeable filter mesh which is configured to releasably retain the filter means.
24. The protective mask of any preceding claim, wherein one or more of the material stiffness, mass, material density, material sound damping properties, shape, or thickness, of one or more portions of the protective mask, or positioning of air outlets thereof, are optimised such that sound in the frequency range of human speech may be transmitted, in use, between the interior of the protective mask and the exterior thereof.
25 A method of manufacturing a protective mask comprising the steps of: forming a body portion comprising a frame and a transparent visor, the body portion being configured to, in use, form an enclosure around at least a portion of the face of a user; providing at least one air inlet; attaching at least one air movement means in fluid communication with the at least one air inlet; installing a filter means; and providing at least one air outlet; wherein the at least one air movement means is configured to move air from exterior of the protective mask, through the at least one air inlet and filter means, to the enclosure.