WO2022229588A1

WO2022229588A1 - Portable sanitisation device for sanitising flexible face masks

Info

Publication number: WO2022229588A1
Application number: PCT/GB2022/000044
Authority: WO
Inventors: Philip Ross NORMAN; Robert GROVER; Daryl Rees
Original assignee: Salupont Consulting Limited
Priority date: 2021-04-30
Filing date: 2022-04-28
Publication date: 2022-11-03
Also published as: GB202106239D0; GB2606226A

Abstract

A portable sanitisation device (10) for sanitising flexible face masks by ultraviolet light irradiation, comprises an openable and closable housing (11), which when closed encloses a treatment chamber with a target irradiation zone to accommodate in a predetermined position therein a flexible face mask in a given generally concavo-convex wear configuration, and ultraviolet light radiation means arranged in the housing to direct ultraviolet light towards the target irradiation zone for irradiation of a face mask when in the zone. The radiation means comprises two opposing pluralities of mutually spaced-apart and three-dimensionally distributed ultraviolet-light-emitting diodes (19, 20) oriented to direct emitted ultraviolet light into the target irradiation zone from multiple directions in three-dimensions for incidence in the case of one plurality (19) on the concave side and in the case of the other plurality (20) on the convex side of a notional three-dimensional region corresponding with the given wear configuration of a face mask when in the predetermined position in the zone. The housing (11) when closed provides a sealed enclosure confining emitted ultraviolet light to the interior of the housing.

Description

PORTABLE SANITISATION DEVICE FOR SANITISING FLEXIBLE FACE MASKS

The present invention relates to a portable sanitisation device for sanitising flexible face masks.

Sanitisation equipment for various types of articles exists in diverse forms and includes portable devices tailored to such tasks as, for example, disinfection or sanitisation of personal articles in the nature of mobile telephones, glasses, keys, wristwatches and other relatively small objects that are worn or carried and as a result may become carriers of microorganisms. The sanitisation procedure generally used in such circumstances is irradiation by ultraviolet light, known as ultraviolet germicidal irradiation. If a target virus is present, the ultraviolet light breaks down the molecular bonds that bind the RNA of the virus, thus preventing it from self-replicating. A lethal dosage for a virus is, for example, 1 ,000 mJ/cm², although it some circumstances it may be double that level. The ultraviolet light initiates a reaction between two molecules of thymine, i.e. one of the bases making up DNA, which disrupts the life cycle and stops multiplication of the virus. The wavelength of ultraviolet light generally considered to have the greatest efficacy in combatting a virus is 100 to 280 nanometres, which is Ultraviolet C (UV-C). UV-C light is much easier to manage in the context of a portable device by comparison with other sanitisation agents such as steam, hydrogen peroxide vapour and gamma irradiation, all of which usually have to be deployed in plant or larger-size apparatus. However, although the mentioned examples of portable sanitisation devices using ultraviolet light are not intended for virus lethality and do not deliver a lethal dose, ultraviolet light, particularly UV-C, is harmful to living organisms and has to be safely confined in a sanitisation equipment even in the case of lower levels of dosage.

In the context of healthcare widespread use is made of face masks to protect both wearers and persons in the vicinity of wearers. Masks provide a screen in relation to exhalation and inhalation of infected air and moisture and function to filter out and entrap microorganisms. Virus microorganisms vary in dimension from 20 to 400 nanometres, which requires use of masks of extremely fine fibres to provide effective entrapment. The filtration effect is frequently enhanced by a multi-layer construction so that the microorganisms are subjected to multiple filtration stages during passage through the mask in either direction. As a consequence of the mask composition and construction, effective sanitisation of face masks is a challenging proposition and the general practice is to discard masks after use, particularly masks used by healthcare and medical workers in conditions of greater exposure to harmful microorganisms. This represents an area of significant wastage and consequently cost and gives rise to the issue of safe disposal, such as by incineration, of potentially dangerously contaminated waste.

It is therefore an object of the present invention to provide a means of sanitisation of flexible face masks, in particular a sanitisation device optimised for treatment in relation to a characteristic face mask shape so that masks can be recovered and recycled for repeat use without premature discard.

A further object is the design of a sanitisation device to be portable and of compact size, so that sanitisation can be safely and effectively carried out wherever convenient and without the constraints imposed by larger installations which work with media such as steam and which require fixtures or at least a fixed location.

Other objects and advantages of the invention will be apparent from the following description.

According to the present invention there is provided a portable sanitisation device for sanitising flexible face masks by ultraviolet light irradiation, comprising an openable and closable housing which when closed encloses a treatment chamber with a target irradiation zone to accommodate in a predetermined position therein a flexible face mask in a given generally concavo-convex wear configuration, the target irradiation zone including a notional three-dimensional region corresponding with the given wear configuration of a face mask when in the predetermined position in the zone, and ultraviolet light radiation means arranged in the housing to direct ultraviolet light towards said notional three-dimensional region for irradiation of a face mask when occupying that region, wherein the radiation means comprises two opposing pluralities of mutually spaced-apart and three-dimensionally distributed ultraviolet-light-emitting sources oriented in each plurality to direct emitted ultraviolet light in cones into the target irradiation zone from multiple directions in three-dimensions for incidence in the case of one plurality on the concave side and in the case of the other plurality on the convex side of a said notional three-dimensional region and the housing when closed provides a sealed enclosure confining emitted ultraviolet light to the interior of the housing. A device embodying the present invention achieves sanitisation by the use of the relatively easily managed medium of irradiation by ultraviolet light, preferably Ultraviolet C, which can be safely deployed by virtue of the openable and closable housing which in closed state confines the light to the housing interior. The device is optimised for treatment of face masks through an arrangement of light-emitting sources in a layout which causes emitted light to be directed into a target irradiation zone from diverse directions in three dimensions so as to act on areas predetermined to be substantially coincident with two opposite sides of a face mask in a specific wear configuration, namely a configuration of generally concavo-convex form. By "generally concavo-convex" there is to be understood a shape which is hollow at one side and consequently outwardly domed on the other side and which does not have to be concavo-convex in a strict geometric sense. Thus, the shape may be defined by surfaces which in places may be flat or flattish rather than wholly curved and may include a fold or ridge, particularly in a region following the line of a mesial plane of a human head in the lower half of the face and thus aligned with and intended to overlie the end of the nose. Flexible face masks are usually capable of folding or collapsing to a generally flat state and unfolding or opening out to a wear configuration compatible with the three-dimensional form of the lower half of the face, thus a generally concavo-convex wear configuration. The treatment chamber of the device is therefore dimensioned to accommodate a mask in such a wear configuration, which is a predetermined or given configuration and thus is represented by the notional three- dimensional region of known form - corresponding with the given wear configuration - in the target irradiation zone even in the absence of a mask. The disposition of the light sources is accordingly selected to provide irradiation of that notional three-dimensional region from multiple directions in three dimensions, thus multiple directions oriented towards each of the convex side and concave side of the notional three-dimensional region in multiple cross-sections of that region. In use the multi-directional irradiation of each of the two sides of a mask in its wear configuration allows the possibility of saturation of the mask with ultraviolet light incident on and passing into the mask so as to achieve an optimal sanitisation action in relation to entrapped microorganisms. Further, a particular advantage of providing pluralities of light-emitting sources, especially an elevated number of sources, is that the desired level of dosage may be achievable with lower-power sources, which is turn reduces or caps the heat development of the sources and thereby enhances light output efficiency or at least ensures that efficiency is maintained.

The sources of at least one of the pluralities are preferably designed for emission of ultraviolet light in a cone, particularly a circular-base cone, with a predetermined cone angle and the sources of that plurality are positioned and oriented so that the cones of light emitted by mutually adjacent sources will intersect in the target irradiation zone at the respective side of the notional three-dimensional region corresponding with the given wear configuration. The resulting overlap of individual throws of light ensures a substantially even distribution of light, thus largely or entirely eliminating shadow areas, and multiplies the intensity of light incident, in use, on any one area of the notional three-dimensional region, i.e. area of the mask, since the light in such an area derives from more than one of the sources. The sources of both pluralities can be arranged in that way, so that there is corresponding action on both the convex side and the concave side of the notional three- dimensional region.

In a preferred embodiment the sources of each plurality are preferably arranged at a predetermined substantially constant spacing from the respective side of the notional three-dimensional region corresponding with the given wear configuration, the predetermined spacing preferably being a spacing which is minimised with respect to distance from a mask so as to avoid undue attenuation of light intensity at the mask, but optimised with respect to proximity to the mask so as to achieve the mentioned preferred overlap of incident light throws. Predetermination of the spacing, which should take into account source layout and individual radiation power, on the basis of the mentioned parameters assists attainment of effective irradiation of mask surfaces with a desired level of dosage of ultraviolet light.

For preference, the sources of at least one of the pluralities are oriented so that the optical axes of the sources are substantially perpendicular to the respective side of said notional three-dimensional region. This feature together with that of the preceding paragraph and the multi-directional radiation in three dimensions is conducive to attainment of substantially equal or constant light intensity at either or each of the convex and concave sides of the notional three-dimensional region and thus, in use, of the irradiated mask.

Realisation of a suitable arrangement of the sources may be achieved in an advantageous manner by three-dimensional distribution of the sources of one of the pluralities at a concavity of the housing and, with similar advantage, those of the other plurality at a convexity of the housing. The concavity and convexity correlate with, respectively, the generally concave side and generally convex side of the generally concavo-convex wear configuration of the mask, more particularly the corresponding notional three-dimensional region of the target irradiation zone. The treatment chamber can then itself be of generally concavo-convex form, but larger in volume than the notional three-dimensional region corresponding with the given wear configuration, in particular larger by a surrounding space accommodating light transmission paths of the sources.

The device may be carried, set up and used particularly conveniently if the housing has substantially the form of a partly flattened hollow sphere, particularly a form which at one side defines a continuously or discontinuously substantially flat support surface and which at the other side is domed similarly to a hemisphere. The housing with such a shape can thus be readily configured to have sufficient volume to accommodate a face mask in the given, i.e. opened-out, wear configuration. Accordingly, a significant feature of a device embodying the present invention may be represented by the device architecture.

For preference, the housing comprises two relatively movable parts, the parts being movable relative to one another for opening and closing the housing. The housing can be composed of more than two parts if appropriate to do so, but limiting the number of parts contributes to economy and ease of assembly and use. Use of the device is particularly simple if the two parts of the housing are pivotably connected together and are pivotable relative to one another for opening and closing the housing, in which case one part of the housing can function as a base and the other part as a cover able to be pivoted or swivelled on the base for opening and closing.

In the case of such a multi-part housing construction it is then advantageous if one of the pluralities of sources is in one of the housing parts and the other one of the pluralities of sources is in the other one of the housing parts, which is a separation conducive to disposition of the two pluralities of sources in the desired arrangement required for irradiation of the stated notional three-dimensional region present corresponding with the given wear configuration.

In a preferred embodiment the radiation means or radiator comprises, in addition to the sources, a reflective boundary surface of the chamber, in which case the reflective boundary surface is arranged to reflect the emitted ultraviolet light so as to irradiate the target irradiation zone from multiple directions in three dimensions. This represents a simple, but effective measure to concentrate irradiation intensity by returning stray emitted light to the target irradiation zone. The provision of a reflective boundary surface in conjunction with multiple sources may contribute to achieving the desired level of dosage with lower-power sources so as to avoid excessive heat output of the sources and consequent reduction in their efficiency. This can be achieved in simple manner if, for example, the boundary surface bounds a concavity of the housing, in particular at the above-mentioned first housing part, so that substantially all reflected light is directed towards the target irradiation zone. However, it may also be of advantage if the reflective boundary surface is shaped to provide chaotic reflection of the emitted ultraviolet light so that a proportion of the reflected light can act in random directions on a mask to ensure irradiation of creases, folds, undercuts, attachments and other irregular shapes that might be present in a mask.

For preference, at least some of the sources are removable from the housing so that replacement of any defective sources can be readily undertaken without the cost of, for example, exchange of a larger part if the sources are integrated fixtures in the part. Accordingly, it is particularly advantageous if the removable sources are mounted in mounts removable from the housing, which eliminates any need to directly handle the sources themselves. Replacement of sources may be facilitated if the removable sources are accessible from outside the treatment chamber for removal, for example if the sources are held in mounts which can be released from and refitted to the housing at an external surface thereof or, preferably, at an internal surface exposed by detaching a protective shell.

In one embodiment the device comprises power supply means for activation of the sources, thus an integrated or on-board power supply which may take the form of, for example, at least one replaceable or rechargeable battery. However, the device can alternatively or additionally be mains-powered.

The device preferably comprises control means, such as controllers or control circuits of a controller, for controlling operation of the sources, the possibilities of control ranging from mere switching on and off to setting and adjustment of operating parameters of a source, a group of sources or selectable sources. For example, control means may be provided to control at least one of the sources with respect to at least one of intensity of emitted ultraviolet light and duration of emission of ultraviolet light and/or to cause each source to provide a predetermined level of dosage of ultraviolet light at a predetermined area in the target irradiation zone. Moreover, the control means may be provided to deactivate the sources if the housing is opened when the sources are emitting, which significantly enhances safety in use of the device by eliminating the risk of escape of ultraviolet light from the housing if unintentionally opened while the sources are active. As a further feature, control means may be provided to deactivate the sources after a predetermined period of time, which enables mask sanitisation by irradiation to be performed for no more than a given time span known to be sufficient to achieve a desired level of efficacy, thus avoiding unnecessary power consumption. Consequently, the predetermined time may be predetermined with respect to a given level of dosage of ultraviolet light in the target irradiation zone.

Advantageously, control means may be provided to detect the total number of operating cycles of each of the sources and to inhibit activation of any of the sources for which attainment of a predetermined number of cycles is detected. This provides an effective means of monitoring source life and providing, if so desired, an indication of a need to replace a source approaching or at the end of its life in terms of the given cycle count. In a further feature of the device, control means may be provided to perform an integrity check of the device prior to each occasion of operation thereof. Such a check can be performed automatically on every occasion of use of the device, so as to ensure an appropriate level of efficiency and safety in sanitisation by the device without the need for a prior user check procedure.

The device preferably comprises fixing means for fixing a mask in the predetermined position, for example by attachment to eyelets, slots or other forms of openings or projections used for retention of ear or head-encircling straps or bands for holding the mask on the head of a wearer or by clips, clamps or other such fasteners attachable to the mask material. The mask can be of such a construction as to be self-supporting in its opened-out wear configuration, for example by virtue of stiffened border regions, but if the device is intended for use with masks which are not self-supporting in that configuration the device can comprise an insert to support a mask in the predetermined position and in the wear configuration, for example an internal frame or structure of minimal size. In that case, the insert preferably has a shape adapted to the shape of a mask in the given wear configuration, so that the mask can be held open in order to by fully irradiated at both sides. The versatility of the sanitisation device may in that case be enhanced if the insert is removable from the housing for replacement by another insert adapted to a different shape of the mask in its wear configuration. The device can then be supplied with several inserts which are configured for different mask types and shapes and which, as required, can be selectively fitted to and removed from the device in simple manner by, for example, detenting.

The present invention also embraces use of a sanitisation device according to the invention for sanitising a face mask, namely a method of sanitising a flexible face mask by the device in which the method comprises the steps of: with the housing in open state placing a flexible mask in the given wear configuration in the predetermined position in the target irradiation zone of the treatment chamber to occupy the notional three-dimensional region corresponding with that wear configuration, closing the housing to seal the treatment chamber against escape of emitted ultraviolet light, causing or allowing activation of the sources for a time sufficient to sanitise the mask by ultraviolet irradiation provided by the radiation means, causing or allowing deactivation of the sources after that time and opening the housing and removing the mask after deactivation of the sources.

Preferred embodiments of the present invention will now be more particularly described by way of example with reference to the accompanying drawings, in which:

Fig. 1 is a schematic perspective view of a sanitisation device embodying the invention, with a housing of the device in open state;

Fig. 2 is a schematic partly sectional side view of the device of Fig. 1 , with the housing in closed state;

Fig. 3 is a schematic perspective view of the rear of the housing, showing a control unit of the device; Fig. 4 is a schematic perspective view of the housing with a top outer shell removed;

Fig. 5 is a schematic perspective view of a removable insert of the housing after removal;

Fig. 6 is a diagrammatic partly sectional view showing, in a first direction, the form of a notional three-dimensional region, which corresponds with a given wear configuration of a face mask, of a target irradiation zone of a treatment chamber of the housing; and

Fig. 7 is a view similar to that of Fig. 6, but showing the region in a second direction orthogonal to the first direction.

Referring now to the drawings there is shown a portable sanitisation device 10 for sanitising flexible face masks by ultraviolet light irradiation, such face masks being of variable design, but commonly of multi-layer synthetic and/or natural fabric sheeting and intended to shroud at least the nostrils and mouth of a wearer. The mask when worn typically extends across the cheeks and lower jaw of the wearer and is attached to the head by, for example, elasticated loops connected with the sheeting at attachment points and engageable around the ears of the wearer. The mask as worn thus has a given wear configuration, from which it can usually be collapsed by folding so as to be more easily carried, and in that wear configuration has a generally concavo-convex shape, which usually departs from a geometrically pure concavity and convexity by, for example, a medial ridge or crease for alignment with and overlying of the dorsum of the nose of a wearer and flatfish areas for overlying the cheeks and lower jaw. The expression generally concavo-convex is thus to be understood in this specification as not limited to a geometrically pure shape. The convex side and concave side represent, respectively, the outside and the inside of the mask as worn. The mask may be substantially self- supporting in the given wear configuration, particularly if it has stiffened edges or borders formed by hemming of the constituent fabric sheeting. The fabric layers may be composed of, for example, fine-fibre spun polypropylene outer layers and at least one inner, sandwiched layer of desired material, the composite serving to permit the passage of respiratory air, but to filter out and entrap airborne microorganisms, especially those of a virus. The described wear configuration thus constitutes a given or predetermined shape which is represented by a corresponding notional three-dimensional region or volume in the absence of the actual mask.

The device 10 comprises an openable and closable housing 11 which in the closed state encloses and seals off a treatment chamber 12 for mask sanitisation. The housing 11 has substantially the form of a partly flattened sphere and is composed of two parts which are relatively movable to open and close the housing. In this embodiment of the device the two parts comprise a dish-like base 13 defining a flat support surface or individual support surfaces lying in a common plane and a domed cover 14 pivotably mounted on the base so that it can be raised and lowered relative to the base and when raised offers good access to the space forming the interior of the housing when closed as well as to a work area around that space, as can be seen in Fig. 1.

The domed cover 14 bounds a concavity at its inside and thereby defines a concave boundary surface 15 of an upper side of the treatment chamber 12. The dish-like base 13 has a convexity projecting, in the closed state of the housing, towards and partly into the concavity, the convexity being defined by a convex surface 16 rising from a floor of the base and positioned concentrically within and at a spacing from a peripheral wall 17 of the base. The wall 17 is internally concave and preferably smoothly transitions, at a separation plane, to the concave surface 15 of the cover 14 when the housing is closed. The treatment chamber 12 is thus present between the concave surface 15 and convex surface 16 as well as the inside of the wall 17 and the floor of the base when the housing is closed. As such, the treatment chamber has a generally concavo-convex shape approximating a hollow hemisphere and is of sufficient volume to accommodate, with a surrounding empty space, an opened-out face mask arranged in the given wear configuration and disposed in a predetermined position in the chamber, specifically a position in which the generally convex side of the mask lies substantially symmetrically within the concavity of the cover 14 and faces the concave surface 15 and in which loop attachment points of the mask are towards the floor of the base 13. Present within the treatment chamber 12 is a target irradiation zone 18 which, as shown more particularly in Figs. 6 and 7, is a notional three-dimensional region corresponding with the afore- described generally concavo-convex shape of a mask in the given wear configuration and in the predetermined position. Although notional, this three-dimensional region - which in use of the device 10 is occupied by the mask in the wear configuration - constitutes a reference body in space for positional referencing of components of the device providing treatment, i.e. sanitisation. Treatment is supplied by way of ultraviolet light radiation means arranged to direct ultraviolet light, especially Ultraviolet C light, towards the target irradiation zone 18 from multiple directions or angles in three dimensions, more particularly towards the envelope of the notional three-dimensional region corresponding with the mask wear configuration. The radiation means comprises a first plurality of spaced-apart UV-light-emitting diodes 19 of, for example, 275 nanometre wavelength and 4.7 mW power distributed three- dimensionally over the concavity of the cover 14, in particular at the concave surface 15, and a second plurality of spaced-apart UV-light-emitting diodes 20 of the same wavelength distributed three-dimensionally over the convexity of the base 13, in particular at the convex surface 16. The diodes 19 are thus directed towards the convex side or convex envelope surface of the notional three-dimensional region or the target irradiation zone 18 and the diodes 20 towards the concave side or concave envelope surface of that region. Each of the diodes 19 of the first plurality is configured to emit ultraviolet light in the form of a cone 19a (shown in Fig. 6 in purely diagrammatic form) generated symmetrically with respect to a diode emission or optical axis 19b, the cone having, for example, a 120 degree cone angle. The orientation and positioning of the diodes 19 is such that the cones of light emitted by mutually adjacent diodes intersect and thus overlap in the target irradiation zone 18 at the convex side of the notional three-dimensional region corresponding with the given wear configuration. Similarly, each of the diodes 20 of the second plurality is configured to emit ultraviolet light in the form of a cone (not shown) symmetrical with respect to a diode emission axis (not shown) and the orientation and positioning of the diodes 20 is such that the cones of light emitted by mutually adjacent diodes of that plurality also intersect and accordingly overlap in the target irradiation zone 18 at the concave side of the notional three-dimensional region. The emission axes of the diodes 19 and - in the illustrated embodiment - most of the diodes 20 are generally perpendicular or normal to the surface of the notional three-dimensional region, in particular the surface area at the point intersected by the axis, whereby the base of the respective cone of ultraviolet light forms on the surface a circle of light of substantially constant intensity. The diode spacing in the case of the diodes 20 is less than in the case of the diodes 19 to take account of a divergence of the emitted light cones of the diodes 20 as opposed to a convergence of the emitted light cones of the diodes 19. The positioning of the diodes to provide overlapping cones of light at the convex and concave sides of the notional three-dimensional region of the irradiation zone 18 is a function of the cone angle, the diode spacing within each plurality and the diode distance from the respectively associated one of those convex and concave sides. The positioning is readily determinable by mathematical modelling on the basis of the notional three-dimensional region as a reference body and/or by use a test piece having a shape corresponding with that region. A factor in establishing the diode distance from the convex or concave side is minimisation of the distance so as to reduce attenuation of emitted light while still achieving overlap. Since face masks are relatively small-size articles and in terms of area do not vary significantly, a distance of about 20 millimetres represents an appropriate compromise. A further factor is the number of diodes, since a greater number increases cost, but the provision of pluralities of diodes allows use of lower-power units which develop less heat and are thus less prone to loss of efficiency due to overheating in the confined space of the treatment chamber 11. With respect to size dictated by a typical face mask in the given wear configuration, an appropriate diode total is about 30 to 60. The effectiveness of the irradiation may be enhanced by providing the surfaces 15 and 16 with a reflective character, for example by metallisation, to multi-directionally reflect incident light, so that ultimately as much of the emitted light as possible is concentrated in the target irradiation zone.

Each of the diodes 19 and 20 is mounted on a respective mount individually removable from the housing for the purpose of exchange. The mounts are concealed by detachable shells forming exterior surfaces of the base 13 and cover 14, the shell of the cover having been removed in the view of Fig. 4 so as to expose the diode mounts of the diodes 19. The diodes are thus readily accessible by shell removal, but at the same time fully protected from contact by users.

Operation of the device 10 is controlled by a control unit, which is indicated generally by 21 and which is conveniently located on the base 13 at the region of pivotal attachment of the cover 14, thus away from the direction of approach to the device when installing and removing a mask. The control unit 21 serves to control, especially, activation of the diodes 19 and 20, such as switching on and off and duration of activation. A particular purpose of the control unit is to ensure delivery by the diodes of a desired dose of ultraviolet light, thus the amount of germicidal ultraviolet energy absorbed by a microbial population over a period of time, calculated to achieve lethality of microorganisms present in an irradiated mask. Calculation is on the basis of - with adjustment for diode distance - the formula UV dose = UV intensity x exposure time in seconds, the control unit determining exposure time by controlling the duration of light emission in a continuous or pulsed output. A lethal dose in the case of UV-C and a porous target surface is approximately 1,000 mJ/cm², assuming the UV fluence is equal to the UV dose. Lethality, as an industry standard, is specified as a 4-log reduction in which a colony is reduced to 100 bacteria after a 99.99% reduction. The control unit 21 can also be adapted to control various parameters of the irradiation, including selective activation of diodes for, for example, more intense exposure of mask regions where microorganisms may be concentrated and variable modulation of light output. Safety measures may also be assigned to the control unit, such as interruption of diode activation if the housing is opened during a treatment phase, monitoring of operating cycles of diodes to detect approach to end of diode life and performance of an integrity check to confirm the functionality of the device prior to each occasion of use.

The predetermined position of a mask in the treatment chamber 12 is established and maintained by fixing means, which in the present embodiment has the form of lugs 22 attachable to the mask at the loop attachment points of the fabric sheeting of the mask. In that case, a mask design optimised for use with the device can be devised, but the fixing means - whether lugs, clips, clamps or other forms of fastener - can be readily designed to co-operate with masks on the market and in general use. The lugs 22 in the case of the device 10 are part of a removable discoid insert 23 shown by itself, i.e. removed from the housing 11, in Fig. 5. When installed, the insert 23 forms the floor of the base 13 and can, if desired, be secured in the installed position. The insert can be replaced by another form of insert adapted to the shape and requirements of a different mask and in the case of a flexible mask without a self-supporting capability the insert can incorporate a suitable support for the mask, for example a frame or similar structure of minimal area.

Use of the device 10 for sanitisation of a mask will be apparent from the foregoing description. With the housing base 13 placed on a suitable support the cover 14 is pivoted up to open the housing and a mask which is to be sanitised and which has been unfolded or is opened out to adopt the given wear configuration is placed in the predetermined position in the target irradiation zone 18 to occupy the notional three-dimensional region corresponding with that wear configuration, the mask being fixed in the predetemined position by attaching to the lugs 22. The cover 14 is then lowered to close the housing and seal the now-formed treatment chamber 12 against escape of emitted ultraviolet light. The two pluralities of diodes 19 and 20 are now activated under the control of the control unit 21 to emit Ultraviolet C light and irradiate both the convex and concave sides of the mask, in that case with complete coverage of the mask surfaces by virtue of the multi directional light radiation in three dimensions and with penetration of the fibre sheeting of the mask. The diodes remain activated for a time predetermined, on the basis of the diode output power and distance from the mask surfaces, to be sufficient to deliver an ultraviolet light radiation dose achieving mortality of entrapped microorganisms in the mask and thus sanitisation of the mask. At the conclusion of that time the diodes 19 and 20 are deactivated by the control unit 21 and the housing opened so that the mask can be detached from the fixing lugs 22 and removed for reuse. The sanitisation time is relatively short and the device 10 can be repeatedly used for subsequent sanitisation cycles without any preparatory actions beyond opening and closing the housing 11 to install contaminated and remove sanitised masks. The compact form and portability of the device allows it to be set up and used in any appropriate location with a suitable mains power supply or in any desired location if the device has an on-board supply.

A sanitisation device embodying the present invention offers the significant advantage of enabling face masks to be sanitised quickly, conveniently and economically so as to be reusable and consequently avoids excessive wastage and the environmental and other problems associated with safe disposal of contaminated material.

Claims

1. A portable sanitisation device for sanitising flexible face masks by ultraviolet light irradiation, comprising an openable and closable housing which when closed encloses a treatment chamber with a target irradiation zone to accommodate in a predetermined position therein a flexible face mask in a given generally concavo-convex wear configuration, the target irradiation zone including a notional three-dimensional region corresponding with the given wear configuration of a face mask when in the predetermined position in the zone, and ultraviolet light radiation means arranged in the housing to direct ultraviolet light towards said notional three-dimensional region for irradiation of a face mask when occupying that region,, wherein the radiation means comprises two opposing pluralities of mutually spaced-apart and three-dimensionally distributed ultraviolet-light-emitting sources oriented in each plurality to direct emitted ultraviolet light in cones into the target irradiation zone from multiple directions in three-dimensions for incidence in the case of one plurality on the concave side and in the case of the other plurality on the convex side of a said notional three-dimensional region and the housing when closed provides a sealed enclosure confining emitted ultraviolet light to the interior of the housing.

2. A device according to claim 1 , wherein the sources of at least one of the pluralities are each constructed for emission of ultraviolet light in a cone with a predetermined cone angle and the sources of that plurality are positioned and oriented so that the cones of light emitted by mutually adjacent sources will intersect in the target irradiation zone at the respective side of said notional three-dimensional region.

3. A device according to claim 1 or claim 2, wherein the sources of each plurality are arranged at a predetermined substantially constant spacing from the respective side of said notional three-dimensional region.

4. A device according to any one of the preceding claims, wherein the sources of at least one of the pluralities are oriented so that the optical axes of the sources are substantially perpendicular to the respective side of said notional three-dimensional region.

5. A device according to any one of the preceding claims, wherein one of the pluralities of sources is three-dimensionally distributed at a concavity of the housing.

6. A device according to any one of claims 1 to 4, wherein one of the pluralities of sources is three-dimensionally distributed at a convexity of the housing.

7. A device according to any one of the preceding claims, wherein the housing has substantially the form of a partly flattened hollow sphere.

8. A device according to one or more of the preceding claims, wherein the housing comprises two relatively movable parts, the parts being movable relative to one another for opening and closing the housing.

9. A device according to claim 8, wherein one of the pluralities of sources is in one of the housing parts and the other one of the pluralities of sources is in the other one of the housing parts.

10. A device according to any one of the preceding claims, wherein the radiation means comprises in addition to the sources a reflective boundary surface of the chamber, the reflective boundary surface being arranged to reflect the emitted ultraviolet light so as to irradiate the target irradiation zone from multiple directions in three dimensions.

11. A device according to any one of the preceding claims, wherein at least some of the sources are removable from the housing.

12. A device according to claim 11, wherein the removable sources are mounted in mounts removable from the housing.

13. A device according to claim 10 or claim 11, wherein the removable sources are accessible from outside the treatment chamber for removal.

14. A device according to any one of the preceding claims, comprising control means to control at least one of the sources with respect to at least one of intensity of emitted ultraviolet light and duration of emission of ultraviolet light.

15. A device according to any one of the preceding claims, comprising control means to cause each source to provide a predetermined level of dosage of ultraviolet light at a predetermined area in the target irradiation zone.

16. A device according to any one of the preceding claims, comprising control means to deactivate the sources if the housing is opened when the sources are emitting.

17. A device according to any one of the preceding claims, comprising control means to deactivate the sources after a period of time predetermined with respect to a given level of dosage of ultraviolet light in the target irradiation zone.

18. A device according to any one of the preceding claims, comprising control means to detect the total number of operating cycles of each of the sources and to inhibit activation of any of the sources for which attainment of a predetermined number of cycles is detected.

19. A device according to any one of the preceding claims, comprising fixing means for fixing a mask in the predetermined position.

20. A device according to any one of the preceding claims, comprising an insert to support a mask in the predetermined position.

21. A device according to claim 20, wherein the insert has a shape adapted to the shape of a mask in the given wear configuration.

22. A device according to claim 20 or claim 21, wherein the insert is removable from the housing for replacement by another insert adapted to a different shape of the mask in its wear configuration.

23. A method of sanitising a flexible face mask by a device according to any one of the preceding claims, the method comprising the steps of: with the housing in open state placing a flexible mask in the given wear configuration in the predetermined position in the target irradiation zone of the treatment chamber to occupy the notional three-dimensional region corresponding with that wear configuration, closing the housing to seal the treatment chamber against escape of emitted ultraviolet light, causing or allowing activation of the sources for a time sufficient to sanitise the mask by ultraviolet irradiation provided by the radiation means, causing or allowing deactivation of the sources after that time and opening the housing and removing the mask after deactivation of the sources.