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The present invention refers to a disinfectant portal structure for disinfection of people, as well as animals, plants and objects, based on ultraviolet radiation in the so-called "far UVC" wavelength, ranging from 207 nanometers to 230 nanometers, that allows in a manner that is simple, versatile, effective, reliable, inexpensive, safe for the health of users, and with a low psychological and emotional impact on users, to disinfect people (as well as animals, plants and objects), inactivating microorganisms and pathogenic agents, in particular the SARS-CoV-2 (i.e. severe acute respiratory syndrome coronavirus 2, also known as Covid-19), without being harmful to people (as well as animals and plants) themselves subjected to ultraviolet radiation treatment in the disinfecting portal structure according to the invention.

It is known that many microorganisms and pathogenic agents are spread by people, even those not infected, since these microorganisms and pathogenic agents are suspended in the air and are carried by people who cross the areas where they are present.

One of the airborne pathogenic agents that has been shown to be particularly contagious and dangerous is SARS-CoV-2, i.e. the severe acute respiratory syndrome coronavirus 2 (also known as Covid-19), which has led many governments around the world to adopt even very severe measures to stop its spread, and that still imposes the use of protective devices, such as face masks, and distancing rules when a person is out of his/her home together with noncohabiting people, especially if indoors. This involves difficulties in any public activity, in particular in the conduct of commercial, catering, transport, education, entertainment and professional activities, since, in addition to the sanitization of the environments where the services are offered and/or the professional activities are provided and to the adoption of health measures required by governments, the participants in such public activities, such as customers of commercial, catering, transport, education, entertainment and professional activities, represent the main vehicle for the introduction of microorganisms and pathogenic agents.

In order to disinfect a person, eliminating or at least drastically reducing the amount of microorganisms and pathogenic agents conveyed by this person, some solutions have been developed in the prior art based on techniques of nebulization of disinfectant substances, such as those disclosed in documents CN111161455A, CN111228549A, KR101119977B1 and KR200441324Y1.

Such prior art solutions suffer from some drawbacks, mainly related to the need to combine a uniform and complete disinfection of the entire surface of a person, in orderto obtain an effective and reliable disinfection in a short time, with a low emotional and psychological impact on the person subjected to disinfection.

Other prior art solutions are also based on germicidal ultraviolet radiation, in the UVC band, conventionally at a wavelength equal to 254 nanometers, for disinfection of objects, as also described in the aforementioned document CN111161455A, where it is expressly recommended that the disinfection process takes place in the absence of people. In fact, the application of UVC ultraviolet radiation for the disinfection process generates harmful interactions with living tissues, such as skin and eyes, whereby ultraviolet radiation is applied to disinfect objects, and more generally non-organic tissues, in the absence of people, animals or plants.

Consequently, the use of ultraviolet radiation, including UVC, in public environments frequented by people (as well as animals) is not applied in the prior art to safeguard the safety of people's health in view of its carcinogenic and cataractogenic effect.

The object of the present invention is therefore to allow disinfecting people, as well as animals, plants and objects, in a manner that is simple, versatile, effective, reliable, inexpensive, safe for the health of users, and with a low psychological and emotional impact on users, inactivating microorganisms and pathogenic agents.

It is specific subject-matter of the present invention a disinfectant portal structure defining a disinfection chamber having an access passage and an exit passage, wherein said disinfection chamber has a base on which it is configured to receive at least one person through said access gate, the disinfectant portal structure comprising one or more ultraviolet radiation lamps configured to radiate, when activated, an ultraviolet radiation having a wavelength ranging from 207 nanometers to 230 nanometers in said disinfection chamber, the disinfectant portal structure comprising a processing and control unit configured to activate said one or more ultraviolet radiation lamps, wherein said one or more ultraviolet radiation lamps are configured to radiate, at each activation, said ultraviolet radiation in an exposure time ranging from 5 seconds to 120 seconds.

According to another aspect of the invention, said wavelength may be ranging from 220 nanometers to 230 nanometers, optionally equal to 222 nanometers.

According to a further aspect of the invention, said one or more ultraviolet radiation lamps may be configured to radiate, at each activation, an exposure dose ranging from 0,5 mJ/cm ² to 3,0 mJ/cm ² , optionally ranging from 0,9 mJ/cm ² to 2,3 mJ/cm ² , more optionally ranging from 1,2 mJ/cm ² to 1,7 mJ/cm ² , of ultraviolet radiation.

According to an additional aspect of the invention, said exposure time may be ranging from 10 seconds to 120 seconds, optionally ranging from 15 seconds to 120 seconds, more optionally ranging from 30 seconds to 100 seconds, still more optionally ranging from 45 seconds to 75 seconds.

According to another aspect of the invention, at least one ultraviolet radiation lamp of said one or more ultraviolet radiation lamps may be located below the base of said disinfection chamber that is at least partially transparent, wherein said at least one ultraviolet radiation lamp is configured to radiate shoe soles supported by the base of said disinfection chamber.

According to a further aspect of the invention, at least part of said one or more ultraviolet radiation lamps may be mounted on a lamp holder frame, controlled by said processing and control unit, that is configured to rotate said at least part of said one or more ultraviolet radiation lamps laterally to said disinfection chamber when said at least part of said one or more ultraviolet radiation lamps is activated.

According to an additional aspect of the invention, the base of said disinfection chamber may be provided with a decontaminating mat having one or more bactericidal adhesive sheets for disinfection of shoe soles.

According to another aspect of the invention, the disinfectant portal structure may further comprise one or more sensors configured to detect access of at least one person to said disinfection chamber through said access passage, said one or more sensors being connected to said processing and control unit, wherein said processing and control unit is configured to activate said one or more ultraviolet radiation lamps when said one or more sensors detect the access of at least one person to said disinfection chamber through said access passage.

According to a further aspect of the invention, said exit passage may be provided with an exit door operatable from inside the disinfectant portal structure.

According to another aspect of the invention, said access passage may be provided with an access door which operatable from outside the disinfectant portal structure.

According to an additional aspect of the invention, the disinfectant portal structure may further comprise locking mechanisms that said processing and control unit is configured to control so as to close the exit door at each activation of said one or more ultraviolet radiation lamps. According to another aspect of the invention, the disinfectant portal structure may further comprise a camera configured to execute one or more operations selected from the group comprising or consisting of detecting a body temperature of at least one person received on the base of said disinfection chamber, acquiring at least one image of a face of at least one person received on the base of said disinfection chamber, and acquiring at least one image of an object brought by at least one person received on the base of said disinfection chamber.

According to a further aspect of the invention: when the camera is configured to detect a body temperature of at least one person received on the base of said disinfection chamber, said processing and control unit may be configured to control said locking mechanisms so as to close the exit door when the camera detects a body temperature higher than or equal to a tolerance threshold, optionally equal to 37,5°C; when the camera is configured to acquire at least one image of a face of at least one person received on the base of said disinfection chamber, said processing and control unit may be configured to execute a processing of said at least one face image and to control said locking mechanisms so as to close the exit door when said processing and control unit does not recognize that said face belongs to a person authorized to leave said disinfection chamber through said exit passage; when the camera is configured to acquire at least one image of an object brought by at least one person received on the base of said disinfection chamber, said processing and control unit may be configured to execute a processing of said at least one image of the object and to control said locking mechanisms so as to close the exit door when said processing and control unit does not recognize that said object authorizes said at least one person to leave said disinfection chamber through said exit passage.

According to an additional aspect of the invention, the disinfectant portal structure may further comprise a visual and/or acoustic signaler, controlled by said processing and control unit, through which said processing and control unit is configured to give information to at least one person received on the base of said disinfection chamber.

According to another aspect of the invention, said processing and control unit may be connected, optionally remotely, more optionally through wireless connection, with a visual and/or acoustic signalling device that gives information to an operator, optionally located in a remote centre.

In particular, the disinfectant portal structure according to the invention comprises an access passage, through which the user enters the structure in which he/she is subjected to the treatment, and an exit passage, which is enabled to allow the exit of the user at the end of the treatment.

Advantageously, the disinfectant portal structure according to the invention is applicable in a common area to access an environment, in particular a room, where a public activity takes place, such as a commercial activity (thereby the environment can be a shop, a shopping centre, a hotel, a vehicle for air, naval or railway transport), a catering activity (thereby the environment can be a bar or a restaurant), an entertainment activity (thereby the environment can be a theatre, a cinema, a discotheque, a swimming pool, a sports centre or a stadium), an education activity (thereby the environment can be a school, university or training centre) and a professional activity (thereby the environment can be a professional firm, office or bank). Advantageously, the disinfectant portal structures according to the invention can be installed in all the entrance (and possibly exit) gates of the environment, in compliance with the rules on emergency exits.

The disinfectant portal structure according to the invention is internally provided with lamps configured to radiate UVC radiation with wavelength ranging from 207 nanometers to 230 nanometers, optionally ranging from 220 nanometers to 230 nanometers, more optionally (substantially) equal to 222 nanometers, having a germicidal and bactericidal action, without causing any side effect for the organic tissues of people (as well as animals and plants) subjected to ultraviolet radiation treatment.

Furthermore, some embodiments of the disinfectant portal structure according to the invention are provided with other internal devices configured to perform other checks on users and to provide information. By way of example, and not by way of limitation, the disinfectant portal structure according to the invention can be provided with a thermal chamber to detect the user's body temperature, preventing him/her from accessing the environment of which the structure constitutes an entrance gate, in case of detection of a high body temperature (e.g. a temperature above 37,5°C that may be a sign of ongoing infection). Alternatively or in combination with the thermal chamber, the disinfectant portal structure according to the invention can be provided with a camera configured to acquire at least one image of the user's face on which a processing unit can be configured to perform a processing, for example for recognition of a user to check that he/she is authorised to enter a reserved environment, or with a device for reading barcodes (e.g. on a ticket to authorise entry to an event, such as a concert or a theatre performance); also, the processing unit can be configured to communicate with apps (e.g. apps intended for tracking the contacts of subjects affected by Covid) installed on user's smartphones and/or with a remote centre to provide the results of the detections and to signal that the user has been disinfected.

The advantages offered by the disinfectant portal structure according to the invention are numerous.

First of all, the disinfectant portal structure according to the invention allows users to be disinfected in a manner that is effective, reliable and safe for health, entailing a favourable psychological and emotional impact on the users themselves who, instead of being discouraged from entering the environment at which the structure is installed, will be encouraged to access an area where all people are subjected to an effective and reliable disinfection treatment.

Furthermore, the disinfectant portal structure according to the invention is simple and consequently inexpensive to manufacture, and its applicability is versatile.

The present invention will be now described, for illustrative but not limiting purposes, according to its preferred embodiments, with particular reference to the Figures of the attached drawings, in which:

Figure 1 shows a perspective view of a first embodiment of the disinfectant portal structure according to the invention;

Figure 2 shows a perspective view of a second embodiment of the disinfectant portal structure according to the invention.

With reference to Figure 1, it can be seen that a first embodiment of the disinfectant portal structure according to the invention comprises a frame 100 that includes a base 110 on which four posts 120 supporting a top roof 130 are mounted. The frame 100 defines an access passage, provided with an access door 140 with handle 145 (optionally an anti-panic handle) operatable from outside the disinfectant portal structure, and an exit passage, provided with an exit door 150 with handle 155 (optionally an anti-panic handle) operatable from inside the disinfectant portal structure; the access passage and the exit passage are advantageously separated and distinct from each other. Advantageously, the access door 140 and the exit door 150 are at least partially transparent to allow a user outside the disinfectant portal structure to see the inside of the structure itself. The frame 100 is further provided with fixed side walls 160 and 170, also advantageously at least partially transparent, which close the inside of the disinfectant portal structure, that is thus accessible only through the access door 140 (and, in principle, the exit door 150). In other words, the disinfectant portal structure is configured to define a disinfection chamber, accessible by a single person at a time through the access passage (although other embodiments of the invention may allow access to more than one person at a time, e.g. in the case of accompanied children and/or families).

The disinfectant portal structure includes four top UVC radiation lamps 200, arranged in correspondence of the four corners of the top roof 130, and four bottom UVC radiation lamps 210 (only three of which are visible in Figure 1), arranged in correspondence of the four corners of the base 110. In particular, the top and bottom UVC radiation lamps 200 and 210 are arranged (and directed) so as to radiate the entire volume of the disinfection chamber defined by the disinfecting portal structure, optionally in a uniform manner, so as to radiate the entirety of the surfaces exposed by a person who enters the inside of the disinfectant portal structure, even if such person is carrying accessories and objects (e.g., bags and mobile phones). In this way, a person (as well as an animal or an object) who is inside the disinfectant portal structure when the top and bottom UVC radiation lamps 200 and 210 are activated, is completely radiated by the UVC radiation emitted by the lamps 200 and 210 themselves.

In particular, the top and bottom UVC lamps 200 and 210 are configured to radiate an ultraviolet radiation in the so-called far UVC wavelength, namely ranging from 207 nanometers to 230 nanometers, optionally ranging from 220 nanometers to 230 nanometers, more optionally equal to 222 nanometers (i.e., substantially equal to 222 nanometers, considering the usual tolerances of the field). Such wavelength range effectively inactivates microorganisms and pathogenic agents, in particular bacteria and viruses including SARS-CoV-2, without harming humans, animals and plants.

In fact, the far UVC radiation in the wavelengths used in the present invention is not even capable to penetrate the outer layer of the skin, nor the outer tear film on the eye surface, of a person (or animal), thereby it does not cause any biological damage in human (or animal) cells. Differently, since bacteria and viruses have extremely small size (of the order of micrometers), the UVC radiation penetrates them and effectively inactivates them, without any carcinogenic or cataractogenic effect for humans (and animals). In particular, scientific experiments have shown that an exposure dose ranging from 0,5 mJ/cm ² to 3,0 mJ/cm ² , optionally ranging from 0,9 mJ/cm ² to 2,3 mJ/cm ² , more optionally ranging from 1,2 mJ/cm ² to 1,7 mJ/cm ² of UVC radiation at a wavelength equal to 222 nanometers, optionally in an exposure time ranging from 5 seconds to 120 seconds, optionally ranging from 10 seconds to 120 seconds, more optionally ranging from 15 to 120 seconds, inactivates 99.9% of the aerial human coronavirus of the alpha and beta subfamilies.

The disinfectant portal structure further includes a panel 300 that houses a processing and control unit connected to one or more sensors (e.g. proximity or presence sensors) configured to detect the access of (at least) one user in the disinfection chamber. Following the detection of such access, the processing and control unit is configured to activate the top and bottom UVC radiation lamps 200 and 210 so as to radiate, at each activation, an exposure dose ranging from 0,5 mJ/cm ² to 3,0 mJ/cm ² , optionally ranging from 0,9 mJ/cm ² to 2,3 mJ/cm ² , more optionally ranging from 1,2 to 1,7 mJ/cm ² of UVC radiations (at wavelengths ranging from 207 nanometers to 230 nanometers, optionally ranging from 220 nanometers to 230 nanometers, more optionally equal to 222 nanometers), in an exposure time ranging from 5 seconds to 120 seconds, optionally ranging from 10 seconds to 120 seconds, more optionally from 15 seconds to 120 seconds, still more optionally ranging from 30 seconds to 100 seconds, even more optionally ranging from 45 seconds to 75 seconds. Other embodiments of the disinfectant portal structure according to the invention may comprise sensors which detect the user's exit from the disinfection chamber through the exit passage (or the access passage) and following which the processing and control is configured to interrupt the activation of the top and bottom UVC radiation lamps 200 and 210; possibly, the disinfectant portal structure can also be provided with locking mechanisms, controlled by the processing and control unit, which close the exit door 150 (and the access door 140) during the activation of the top and bottom UVC radiation lamps 200 and 210.

Also, the panel 300 further houses a thermal camera 310 for detecting the user's body temperature, that is connected to the processing and control unit, and a camera, advantageously coinciding with the thermal camera 310, configured to acquire at least one image of the face of the user present in the disinfection chamber and/or of an object (such as a badge or a ticket) carried by the user. In this case, if a high body temperature is detected (e.g. a temperature above 37,5°C that may be a sign of infection in progress), the processing and control unit is configured to prevent (through locking mechanisms of the exit door 150) access to the environment where a public activity takes place (e.g. a shop, a shopping centre, a hotel, a vehicle for air, naval or railway transport, a bar, a restaurant , a theatre, a cinema, a discotheque, a stadium, an office or a bank) that is in communication with the exit passage of the disinfectant portal structure. Moreover, the processing and control unit is configured to perform a processing of said at least one image of the user's face, for example to recognise a user. Furthermore, the processing and control unit is configured to perform a processing of said at least one image of an object, for example to open the locking mechanisms of the exit door 150 following recognition of a ticket or badge (e.g., through a barcode) that authorises entry to an event (such as a concert or a theatre performance) that takes place in the environment that is in communication with the exit passage of the disinfectant portal structure.

Furthermore, the panel 300 still houses a visual and/or acoustic signaler 320, controlled by the processing and control unit, through which the processing and control unit is configured to provide information to the user present in the disinfection chamber, for example relating to the operations carried out and/or the environment where a public activity takes place that is in communication with the exit passage of the disinfectant portal structure.

In some embodiments of the disinfectant portal structure according to the invention, the processing and control unit is further connected, optionally remotely, more optionally through wireless connection, with a visual and/or acoustic signalling device that provides information to an operator who controls accesses to the environment where a public activity takes place that is in communication with the exit passage of the disinfectant portal structure. By way of example, this visual and/or acoustic signalling device can be located in a remote centre of the operator, possibly connected to a plurality of portal structures which allow entry to the environment (for example a shopping centre).

Advantageously, the material of which the disinfectant portal structure according to the invention is made has characteristics of environmental sustainability and recyclability.

It must be noted that, although in Figure 1 the frame 100, and consequently the disinfectant portal structure, has the shape of a parallelepiped with rectangular base, other embodiments of the disinfectant portal structure according to the invention can have the frame having any shape, even with different conformation (e.g. cylindrical, with sliding doors, without posts or with a different number of posts), still remaining within the scope of protection of the invention as defined by the attached claims.

By way of example, Figure 2 shows a second embodiment of the disinfectant portal structure according to the invention, that comprises a frame that includes a base 110 on which a cylindrical wall 180 having a top roof 130 is mounted. The cylindrical wall 180 has an access passage, provided with a sliding access door 143, operatable from outside the disinfectant portal structure (optionally through a button and/or a proximity sensor, wherein the opening can be conditioned upon the absence of a user inside the portal structure), and an exit passage, provided with a sliding exit door (not shown in the Figure) operatable from inside the disinfectant portal structure (optionally through a button, wherein the opening can be conditioned upon completion of the treatment through ultraviolet radiation of the user present inside the portal structure). Consequently, also the disinfectant portal structure of Figure 2 is configured to define a disinfection chamber, accessible by a single person at a time through the access passage (although other embodiments of the invention may allow access to more than one person at a time, e.g. in the case of accompanied children and/or families).

The disinfectant portal structure of Figure 2 includes a lamp holder frame comprising two vertical lateral arms 400 (i.e. arranged substantially orthogonal to the base 110 and to the top roof 130), only one of which is visible in Figure 2, joined by a horizontal intermediate arm 410 (i.e. arranged substantially parallel to the top roof 130) the central portion of which is connected to the rotating shaft of an electric motor 420 in turn connected to the top roof 130. It must be noted that further embodiments of the invention may comprise any number of lateral arms, for example only one or three or more (in this case joined together through a plurality of radial intermediate arms, optionally angularly equidistant from each other, centrally connected to the rotating shaft of an electric motor 420), and/or that the lateral arms may be not substantially orthogonal to the base 110 and to the top roof 130 and/or that the intermediate arm 410 (or the radial intermediate arms) may be not substantially parallel to the top roof 130.

Each one of the two lateral arms 400 is provided with four side UVC radiation lamps 250, arranged at respective heights, different from each other, with respect to the base 110 (i.e. at respective distances, different from each other, from the top roof 130) and which are advantageously directed towards the inside of the disinfection chamber. Also these side lamps 250 are configured to radiate an ultraviolet radiation in the wavelength ranging from 207 nanometers to 230 nanometers, optionally ranging from 220 nanometers to 230 nanometers, more optionally equal to 222 nanometers (i.e. substantially equal to 222 nanometers, considering the usual tolerances of the field).

The electric motor 420 is controlled by the processing and control unit so as to be activated during the activation of the side UVC radiation lamps 250. In other words, the lamp holder frame is rotating during the activation of the side lamps 250. In this way, the side lamps 250 are configured to rotate laterally to the disinfection chamber defined by the disinfecting portal structure during the emission of UVC radiation so as to radiate the entire volume of the disinfection chamber itself, optionally in a uniform manner, so as to radiate the entirety of the surfaces exposed by a person who enters the disinfectant portal structure, even if such person is carrying accessories and objects (e.g., bags and mobile phones). In this way, a person (as well as an animal or an object) who is inside the disinfectant portal structure when the UVC radiation side lamps 250 are activated, is completely irradiated by the UVC radiation emitted by the side lamps 250 themselves.

It must be noted that also the disinfectant portal structure shown in Figure 1 could have, in combination or alternatively to the top and bottom lamps 200 and 210, a lamp holder frame similar to that shown for the disinfectant portal structure of Figure 2, i.e. a lamp holder frame provided with side lamps 250 and configured to be rotated during the activation of the side lamps 250 (advantageously occurring simultaneously with the possibly present top and bottom lamps 200 and 210).

Also, it must be noted that further embodiments of the disinfectant portal structure according to the invention may have a frame without fixed side walls, for example because the disinfectant portal structure is inserted inside an already existing environment the conformation of which prevents bypassing the disinfectant portal structure (e.g. a corridor the width of which corresponds to that of the disinfectant portal structure), still remaining within the scope of protection of the invention as defined by the attached claims.

Furthermore, it must be noted that other embodiments of the disinfectant portal structure according to the invention may have the access and exit doors, as well as possible fixed walls closing the frame of the disinfectant portal structure, which are not transparent, in order to better preserve the privacy of a user located inside the disinfectant portal structure, still remaining within the scope of protection of the invention as defined by the attached claims.

It must be also noted that further embodiments of the disinfectant portal structure according to the invention may have a different number of UVC radiation lamps than what shown in Figure 1, namely one or more UVC radiation lamps, positioned (and directed) also according to a different arrangement than that shown in Figure 1 (e.g. linear lamps positioned, optionally inside respective posts, laterally to the disinfection chamber so as to radiate - at least - towards the inside of the disinfection chamber itself), still remaining within the scope of protection of the invention as defined by the attached claims. In particular, certain embodiments of the disinfectant portal structure according to the invention can have one or more base UVC radiation lamps located below the base 110, that is at least partially transparent, to also radiate the shoe soles of a user. Other embodiments of the disinfectant portal structure according to the invention can be provided, alternatively to or in combination with such one or more base UVC radiation lamps located below the base 110, with a decontaminating mat having one or more bactericidal adhesive sheets for disinfection of the user's shoe soles.

As stated, the disinfectant portal structure according to the invention defines a disinfection chamber accessible by one or more people, preferably by a single person at a time, and is configured to be positioned at an entrance of an environment where a public activity takes place, such as a commercial activity (thereby the environment can be a shop, a shopping centre, a hotel, a vehicle for air, naval or railway transport), a catering activity (thereby the environment can be a bar or restaurant), an entertainment activity (thereby the environment can be a theatre, a cinema, a discotheque or a stadium) and a professional activity (thereby the environment can be an office or a bank). In other words, the disinfectant portal structure according to the invention is configured to operate as an entrance gate to the environment where a public activity takes place; in particular, the exit passage of the disinfectant portal structure according to the invention acts as an entrance to the environment where the public activity takes place.

In this regard, the irradiation of a person in the disinfection chamber of the disinfectant portal structure according to the invention with an exposure dose ranging from 0,5 mJ/cm ² to 3,0 mJ/cm ² , optionally ranging from 0,9 mJ/cm ² to 2,3 mJ/cm ² , more optionally ranging from 1,2 mJ/cm ² to 1,7 mJ/cm ² , of UVC radiation at wavelengths ranging from 207 nanometers to 230 nanometers, optionally ranging from 220 nanometers to 230 nanometers, more optionally equal to 222 nanometers, in an exposure time ranging from 5 seconds to 120 seconds, optionally ranging from 10 seconds to 120 seconds, more optionally from 15 seconds to 120 seconds, still more optionally ranging from 30 seconds to 100 seconds, even more optionally ranging from 45 seconds to 75 seconds, is below the limits set by international protection standards. In fact, current guidelines of the International Commission on Non-Ionizing Radiation Protection (ICNIRP) establish that the dose limit for radiation at a wavelength equal to 222 nanometers is 23 mJ/cm ² for 8 hours of exposure. Consequently, the exposure for the significantly lower doses indicated above (i.e., ranging from 0,5 mJ/cm ² to 3,0 mJ/cm ² at each activation) and a much more limited time (i.e. ranging from 5 to 120 seconds, e.g. ranging from 10 to 30 seconds), are compatible with the protection standards established by the ICNIRP.

The preferred embodiments of this invention have been described and a number of variations have been suggested hereinbefore, but it should be understood that those skilled in the art can make other variations and changes without so departing from the scope of protection thereof, as defined by the attached claims.