WO2022031233A1

WO2022031233A1 - Ultraviolet (uv) disinfection device

Info

Publication number: WO2022031233A1
Application number: PCT/SG2021/050457
Authority: WO
Inventors: Yu Lee TAN
Original assignee: Ligera Research Pte. Ltd.
Priority date: 2020-08-04
Filing date: 2021-08-04
Publication date: 2022-02-10

Abstract

The invention relates to a disinfection device with at least a tunnel shaped enclosure using at least an ultraviolet (UV) radiation source, at least one re-focusing reflector and at least one diffusing reflector. The diffusing reflector is located on the inner surface of the enclosure and reflects the UV radiation in a diffused pattern thereby multiplying the effect of the UV radiation. The re-focusing reflector reflects and re-directs the UV radiation towards at least one diffusing reflector or towards at least one re-focusing reflector such that any UV radiation originating from the UV radiation source cannot directly transmit out of the enclosure.

Description

ULTRAVIOLET (UV) DISINFECTION DEVICE

TECHNICAL FIELD

The invention relates to a disinfection device with at least a tunnel shaped enclosure 10 using at least an ultraviolet (UV) radiation source 20 and diffusing reflectors 40 which are able to reflect the UV radiation in a diffused pattern. Re-focusing reflectors 30 reflect the UV radiation back into the tunnel shaped enclosure 10 wherein the diffusing reflectors 40 continually reflect and diffuse the UV radiation into a multitude of directions thereby multiplying the effect of the UV radiation.

BACKGROUND OF THE INVENTION

Most disinfection systems using ultraviolet (UV) radiation are used to disinfect either water or air and hence most prior art of UV disinfection work in chambers. Although, there is prior art which disinfects rooms with UV radiation and UV devices to disinfect food items, but there is no prior art which teaches multiple re-direction of UV radiation so that the disinfecting UV radiation is diffused in a multitude of directions in order to disinfect surfaces of solid objects.

Disinfecting the outer surfaces of solid objects like personal protective equipment (PPE), clothing and people are much more challenging than disinfecting air, water and smooth surfaces. Fibres in a face mask or clothing are more than enough to shield viruses and bacteria from UV radiation making the UV germicidal radiation less effective. In fact, scientific studies were unable to achieve consistent results when using UV radiation to disinfect N95 fabric for short exposure times even with much higher doses of UV radiation than used for smooth surfaces.

In order for Ultraviolet Germicidal Irradiation (UVGI) to work effectively on the external surfaces of solid objects, the UV radiation must come from a multitude of different directions to overcome multitude of different surface properties. The COVID19 pandemic has shown that medical personal protective equipment (PPE) can be in very short supply when there is a pandemic. Tons of disposable face masks alone are discarded on a weekly basis. This represents contaminated waste which can be drastically reduced by the present invention which can disinfect PPE and help to extend their use. Furthermore, entrances to mass transit areas, shopping malls and airports can all use the present invention to disinfect people and their clothing instead of spraying chemical disinfecting solutions. It has also been found that people have been infected from viruses surviving on frozen food. The requirement for UVGI to be effectively employed on the outer surfaces of solid objects have never been more urgent.

UV radiation is also commonly used to disinfect food items prior to packing. The common configuration of these UV food disinfection is a tunnel with many UV mercury lamps disposed within the tunnel with the entrance and exit to the tunnel covered by a strip curtain to prevent the UV radiation from escaping from the tunnel. This type of food disinfection machines can also be vastly improved with the present invention.

Chen et al. (US010370267) and Clark et al. (US20040166018) both teach diffused reflectance of UV radiation in water and air, respectively. Both these prior art teach UV disinfection in chambers. Chen et al. (US010370267) teaches a method of disinfecting water whilst Clark et al. (US20040166018 & US8404186) teaches an air sterilization chamber. In fact, there are two patent registrations US20040166018 and US 8404186 invented by Clark et al. both entitled ‘UV FLUX MULTIPLICATION SYSTEM FOR STERILIZING AIR, MEDICAL DEVICES AND OTHER MATERIALS’ fail to teach how anything other than air can enter the UV sterilization chamber nor do these patents teach how surfaces of solid objects can be disinfected. Therefore, it can be said that UV disinfection of solid objects using UV radiation and diffusing reflectors is not obvious. Clark et al. (US20040166018 & US 8404186) also does not teach about reflecting or redirecting light back into the enclosure but rather claims openings which let light through and further teaches means to block the light from escaping.

Furthermore, Clark et al. (US20040166018 & US8404186) claims a sterilization system for air but does not teach how the system can reach 100% disinfection. Furthermore, High-Efficiency Particulate Arrestance (HEPA) and Ultra Low Particulate Air (ULPA) filters only filter particles including microorganisms larger than 0.3 microns and 0.1 microns respectively and thus also cannot offer 100% disinfection. CLARK et al. (US20040166018 & US8404186) teaches using an expanded polytetrafluoroethylene (PTFE) reflector as an inner surface of a chamber to create a ‘UV flux’ in a chamber and also teaches perforated end plates with inner reflective coating. Perforated material will invariably allow air to flow through but also allow UV radiation through. At a microscopic level, the same can be said for expanded PTFE.

CLARK et al. (US20040166018 & US8404186) discloses a ‘flux multiplying light trap’ for a chamber which uses a packed array of highly reflective fibers held by a frame at both the inlet and outlet but is unclear about where this ‘flux multiplying light trap’ is formed, where the light source is or where the light incident light is reflected. It can only therefore be assumed that CLARK et al. (US8404186) teaches the ‘flux multiplying light trap’ as being the packed array of reflective fiber housed within a frame.

CLARK et al. (US20040166018 & US8404186) does disclose an embodiment for sterilization of surfaces of three dimensional objects where the UV light source is placed outside the sterilization chamber.

CLARK et al. (US20040166018 & US8404186) specifically claims two apertures i.e. openings to let light through then teaches means to block UV light from escaping a chamber by means of moving slats, perforated end plates and a ‘flux multiplying trap’ using expanded PTFE which is also a material that has a pore structure with perforations. Prior art does not teach any re-focusing reflector located at both the inlet or outlet of a tunnel shaped enclosure wherein the said reflector reflects and re-directs UV light to diffusing reflectors or another re-focusing reflectors.

SUMMARY OF THE INVENTION

The present invention teaches a novel disinfection device with at least a tunnel shaped enclosure 10 using at least an ultraviolet (UV) radiation source 20 and diffusing reflectors 40 which are able to reflect the UV radiation in a diffused pattern. Re-focusing reflectors 30 reflect and re-direct the UV radiation back into the tunnel shaped enclosure 10 wherein the diffusing reflectors 40 continuously reflect and diffuse the UV radiation into a multitude of directions thereby multiplying the effect of the UV radiation. The present invention in various embodiments disinfects air, water and external surfaces of solid objects although the main focus is on air and solid objects.

It is a well known fact that UVGI is highly effective. It is also recently been proven that UV radiation of 220nm and 260nm wavelength is also extremely effective at disrupting DNA and RNA strands. Wavelengths close to the wavelengths of 220nm and 260nm are also very effective. UV radiation of 222nm wavelength has also been shown to be safe as it does not harm the retina or the skin tissue of mammals. There is now great interest in this wavelength of UV radiation. Thus, the disinfection device of the present invention may also use this particular wavelength of 222 nm and thus will disinfect bacteria, fungi and viruses but will be harmless to humans. Currently, rays of wavelengths less than 240nm produce ozone which is toxic for humans whilst rays with wavelengths above 240nm destroy ozone. UV rays of 222nm wavelengths do produce ozone but much less than the known ozone producing wavelengths of 185nm. UV rays of 222nm wavelengths produce 0.005 ppm of ozone at an irradiance of 2mJ/cm² which is only a tenth of the recommended safe exposure limit. However, as the device of the present invention multiplies the light by repeated diffused reflectance hence substantially increasing the irradiance, the ozone produced is also increased. It is therefore prudent to assume that with the increase of intensity of UV 222nm irradiation, the ozone created will be beyond safe limits and a system which uses this wavelength for human occupied areas must also remove ozone. The embodiment for use for human occupied areas circulates air in such a way that ozone is removed from human occupied areas into ducts which uses the device of the present invention with a UV radiation source 20 of greater 265nm to entirely remove the ozone and further disinfects the air which is then re-circulated back to the human occupied area.

The present invention also teaches how to let airflow through ends 12,14 of the tunnel shaped enclosure 10 and how to concurrently impede the UV rays from the UV radiation source 20 from escaping the tunnel shaped enclosure 10. Unlike prior art which teaches means to block UV light from escaping, the present invention uses the fact that light travels in a straight line and therefore teaches an arrangement of openings 13 and refocusing reflectors 30 to prevent UV light from escaping the tunnel shaped enclosure 10. The present invention also teaches the use of a porous material which has a similar principle of arrangement which is suitable for use as a re-focusing reflector 30.

For disinfecting air, the present invention teaches an embodiment where re-focusing reflectors 30 which are made of porous hydrophobic UV reflective material. This embodiment for disinfecting air to be used in ventilation systems also uses a combination of re-focusing reflectors 30 for the inlet 12 and the outlet 14 of the tunnel shaped enclosure 10. This is a very effective means of disinfection particularly for viruses and bacteria carried by liquid microdroplets. An enhanced embodiment for disinfecting viruses in liquid microdroplets is one with an additional hydrophobic filter 70 which is UV reflective illustrated in FIG. 9.

An embodiment of the present invention also includes a transparent support structure 60 to support solid objects as they progress through the tunnel shaped enclosure 10. The transparent support structure 60 also permits UV rays to pass through the said structure and not just visible light rays. This is critical to ensuring that every part of the solid object being disinfected is exposed to the UV rays reflected from the diffusing reflectors 40.

For the embodiments for disinfecting PPE, a conveyor system 50 is preferred over the transparent support structure 60.

Starry et al. (US7660040) teaches a diffused reflective article with mean pore sizes of less than 1 pm. Porous PTFE has been shown to have good reflectivity with no appreciable difference in reflectivity with pore sizes from 2 pm to 7 pm. The diffusing reflectors 40 and re-focusing reflectors 30 used in the present invention may have either Lambertian or specular reflectance properties. For Lambertian reflectance, the present invention may use porous PTFE or the diffused reflective article as taught by Starry et al. (US7660040). Sintered PTFE (also porous) is the preferred material for diffusing reflectors 40 and re-focusing reflectors 30 particularly for embodiments to disinfect air. For diffusing reflectors 40 using materials for with specular reflectance, convex protrusions in the material provide a diffused reflectance such that irradiance in the tunnel shaped enclosure 10 is uniform. BRIEF DESCRIPTION OF THE DRAWINGS

In order that the invention may be more readily understood and put into practical effect, a preferred example of the invention will now be described with reference to the accompanying drawings which are as follows:

FIG 1. Side view embodiment for disinfecting air illustrating different configurations of re-focusing reflectors 30 at the inlet 12 and outlet 14

FIG 2. Side view of embodiment illustrating the re-focusing reflector 30 for disinfecting a fluid

FIG 3. Frontal cross-sectional view of tunnel shaped enclosure 10 (with re-focusing reflectors 30 removed) for disinfecting medical masks and gowns illustrating preferred position of UV radiation source 20 and conveyor system 50

FIG 4A. Side view of embodiment for disinfecting solid objects with movable trap door section 5 closed

FIG 4B. Side view of embodiment for disinfecting solid objects with movable trap door section 5 open

FIG 4C. Side view of embodiment for disinfecting solid objects with movable trap door section 5 at outlet 14 closed

FIG 4D. Side view of embodiment for disinfecting solid objects with movable trap door section 5 open

FIG 4E. Side view of cylindrical transparent support structure 60 with ridge-like protrusion 65

FIG. 5. Top view of longitudinal sectional view of embodiment for high capacity throughput

FIG. 6. Show dispersed reflectance using convex protrusions on a specular surface

FIG. 7. Scanning Electron Microscope (SEM) picture of sintered PTFE

FIG. 8. Scanning Electron Microscope (SEM) picture of expanded PTFE

FIG. 9. Embodiment with UV reflective hydrophobic filter 70 DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

All embodiments of the present invention use an enclosure where at least UV radiation source 20 within the enclosure is prevented from escaping by re-focusing reflectors 30 whilst diffusing reflectors 40 continually reflect the UV radiation in a diffused pattern thereby multiplying the UV irradiance within the enclosure whilst ensuring even irradiance. For the embodiments of the present invention to disinfect, the objects to be disinfected must enter this enclosure.

For the embodiment to disinfect air differs from prior art and in particular Clark et al. (US20040166018 & US8404186) in that it contains no moving parts and the openings in the present invention allow air to flow through but do not allow direct transmission of the UV radiation through. FIG. 1 depicts this embodiment which illustrates to different variations of re-focusing reflectors 30. The re-focusing reflectors 30 at the inlet 12 have visible openings 13 whilst the refocusing reflectors 30 at the outlet 14 have microscopic pores. The said microscopic pore structure of sintered PTFE is illustrated in FIG. 7. This pore structure is very different to Clark et al. (US20040166018 & US8404186) which uses expanded PTFE of which the pore structure is illustrated in FIG. 8. As can clearly be seen, Clark et al. (US20040166018 & US8404186) teaches the use of a material which allows UV light to transmit directly through whilst sintered PTFE has a pore structure like a sponge which allows air to flow through but does not allow UV light to transmit through directly. FIG. 7 and FIG. 8 are Scanning Electron Microscope (SEM) photos courtesy of Porex Filtration Group.

The re-focusing reflectors 30 at the inlet 12 and the visible openings 13 are also arranged in such a way that UV light cannot transmit directly through the said openings 13 and out from the enclosure 10. This is the distinct difference to prior art. Furthermore, Clark et al. (US20040166018 & US8404186) teaches a light multiplying trap comprising a mat of fibers housed in a frame which is also very different from the embodiment of the present invention for disinfecting air which uses sintered PTFE as a re-focusing reflector 30 which does not need to be housed in a frame because of its inherent more rigid structure. Sintered PTFE is also produced by sintering particles of PTFE with cellulose to form the desired pore structure and does not use any of the binders listed in Clark et al. (US20040166018 & US 8404186).

The tunnel shaped enclosure 10 has a length determined by the time it takes for disinfection which is dependent on the irradiance which is in turn a function of the radiation from the UV radiation source 20 and the reflectivity of the diffusing reflectors 40 and the re-focusing reflectors 30. The other factor which affects the length of the tunnel shaped enclosure 10 is the speed of the particles or objects moving through the tunnel shaped enclosure 10. Embodiments where the length of the tunnel shaped enclosure 10 needs to be kept to a minimum, must use means to control the speed of the items being disinfected.

Porous sintered PTFE as a re-focusing reflector 30 helps to slow down liquid droplets in embodiments for air ducts and portable disinfecting breathing devices whilst a conveyor system 50 would be required for embodiments needing to control the speed of solid objects passing through the tunnel shaped enclosure 10. A portable disinfecting breathing device in the context above is any portable device using an embodiment of the present invention which disinfects ambient air for breathing which may be in the form of a face mask or a filter device below a face shield. Embodiments to disinfect PPE is one example where a conveyor system 50 is preferred over the embodiment with the transparent support structure 60. As for embodiments for disinfecting air where liquid microdroplets need to be slowed down to be disinfected, a further hydrophobic filter 70 can be used in the air flow, disposed within the tunnel shaped enclosure 10 covering the entire cross-section of the tunnel. This hydrophobic filter 70 is also made out of sintered PTFE sheet and is reflective on both sides and thus divides the tunnel shaped enclosure 10 into two halves of which each half has a hydrophobic surface to slow the progress of liquid microdroplets which contain the microorganisms to be disinfected and each half also forms its own enclosure where UV radiation is multiplied and thus ensuring a complete disinfection of microorganisms carried by liquid microdroplets. This is the key distinguishing feature of the embodiment of the present invention for disinfecting air. Air flow is increased because ultra fine filters are not used to filter out small particulate contaminants as in prior art but rather microdroplets greater than 5 pm are temporarily trapped for sufficient time for the UV radiation from the UV radiation source 20 to effectively deactivate infectivity of bacteria and viruses. Ultra Low Particulate Air (ULPA) filters are able to arrest 99.999% of particles larger than a 0.12 pm or 120nm. Sizes of viruses are mostly submicro scopic measuring between 5 nm to 300 nm. The corona viruses measure between 60 nm to 140 nm with the average size being 125 nm. Those skilled in the art will agree that ULPA filters are thus not able to arrest all viruses. However, the embodiment of the invention using sintered PTFE filters particularly as a hydrophobic filter 70 can deactivate viruses in liquid microdroplets. A small liquid droplet is around 5 pm in diameter. Thus, the sintered PTFE filters can have a pore size significantly larger than of the ULPA filters and thus provides better air flow but also better disinfection capabilities when used in the present invention. Very fine droplets of water measuring less than 5 pm in diameter may still penetrate the larger pores of the sintered PTFE but because of the sponge-like nature of the pores, the liquid droplet will be caught and slowed by the porous structure of the material wherein the surface tension of the water will ensure the liquid droplet sticks to the porous re-focusing reflector 30. This is highly desirable because viruses are commonly spread through liquid droplets. Therefore, the porous re-focusing reflector 30 and hydrophobic filter 70 provide the vital function of slowing the liquid microdroplets bearing viruses such that there is sufficient exposure time to the UV irradiance and thus ensuring complete disinfection of all viruses entering the UV disinfection device of the present invention. This embodiment of the present invention is also scalable and may be used in large ventilation ducts or may also be used in a device as small as a medical face mask. Regardless of size, this embodiment to disinfect microorganisms (especially viruses) suspended in liquid microdroplets is an improvement over prior art.

The preferred embodiment to disinfect PPE (masks and gowns) would use a conveyor system to control the movement through the tunnel shaped enclosure 10. This conveyor system would comprise a motor driving a belt wherein the belt would be covered in UV reflective material and will also have a means to attached the PPE. The said attachment means 16 would be in the form of hooks, hangers or clips to hold the masks or gowns and will be made of a UV transparent material as in the transparent support structure 60.

The re-focusing reflector 30 reflects and re-directs UV radiation back into the tunnel shaped enclosure 10 thereby preventing UV rays from escaping. This re-focusing reflector 30 can be made from a single moulded curved surface reflector for embodiments where the tunnel shaped enclosure 10 is for small objects. For larger tunnel shaped enclosures 10 demanding a larger re-focusing reflector 30, multiple reflective panels may be used to form the re-focusing reflector 30. In this embodiment, the re-focusing reflector 30 has many reflective surfaces all reflecting light into the tunnel shaped enclosure 10. For this embodiment with multiple surfaces to reflect UV radiation back into the tunnel shaped enclosure 10, it is also possible to have spaces between the surfaces such that air or water can flow through yet the UV radiation cannot escape the tunnel shaped enclosure 10 as long as the re-focusing reflectors 30 face diffusing reflectors 40 or at another reflective surface in the tunnel shaped enclosure 10. Thus, the present invention in this embodiment can disinfect air and water with an improvement over prior art. FIG. 2 illustrates an embodiment where flow of a fluid is the least impeded by the re-focusing reflectors 30 whilst the UV radiation retained in the tunnel shaped enclosure 10 is maximized. FIG. 5 illustrates another embodiment of the present invention where the re-focusing reflectors 30 are in a configuration where people and objects can enter the tunnel shaped enclosure 10 without the need for movable trap doors or sections 5 of the present invention which create temporary openings.

The preferred option for the present invention would be to use re-focusing reflectors 30 which are specular in order to better control the direction of incident light. However, for the embodiment of the present invention for disinfecting air, the use of porous PTFE as a re-focusing reflector 30 makes sense as the material allows air to flow and is also an excellent UV reflector. Although sintered PTFE has Lambertian reflective properties, sintered PTFE also has a microscopic pore structure which prevents the UV radiation from being transmitted out of the tunnel shaped enclosure 10 directly. Thus, the re-focusing reflector 30 made from sintered PTFE may face directly into the tunnel shaped enclosure 10 and the said reflector will reflect the majority of UV radiation to the re-focusing reflectors 30 at the other end of the tunnel shaped enclosure 10 or to diffusing reflectors 40 or to a hydrophobic filter 70 (if one is used).

The present invention also teaches embodiments for disinfecting external surfaces of solid objects using a conveyor system 50 or a transparent support structure 60 to support the solid objects through the tunnel shaped enclosure 10. This is not possible with any of the embodiments described in Clark et al. (US 20040166018 & US8404186). An efficient way of UV disinfection is if the objects being disinfected are continually moving whilst being disinfected as in the present invention where the tunnel shape enclosure 10 is open at two ends 12,14 as illustrated in FIG. 5. However, to engineer a conveyor system to move solid objects into the tunnel shaped enclosure 10 in a non-linear manner is more mechanically complex and trap doors 5 where temporary openings are created sections of the present invention are thus preferred for solid objects due to simplicity of design.

An embodiment of the invention to disinfect external surfaces of solid object with less mechanical complexity is one with trap doors 5 and a transparent support structure 60. The transparent support structure 60 suspends objects in the tunnel shaped enclosure 10 whilst allowing UV radiation to pass through the the transparent support structure 60 and disinfect the underside of the said objects. The transparent support structure 60 may be made of UV transmitting acrylic which allows up to 92% UV ray transmission. FIG. 4A to FIG. 4D illustrates this embodiment with the transparent support structure 60. FIG. 4E illustrates the cylindrical or tunnel shaped transparent support structure 60 which rotates about its longitudinal axis. This particular embodiment allows items like clothing to tumble through the transparent support structure 60 and hence through the tunnel shaped enclosure 10. The said cylindrical transparent support structure 60 may be perforated to allow more UV radiation through the said transparent support structure 60 and to make the transparent support structure 60 lighter. The said cylindrical transparent support structure 60 of this preferred embodiment for disinfecting clothing items also has ridge-like protrusion 65 on the inner surface of the cylindrical transparent support structure 60 to provide traction such that the clothing items are lifted with the rotation of the cylindrical transparent support structure 60. Gravity makes the clothing items then fall to the bottom of the cylindrical transparent support structure 60 when they reach the top of the cylindrical transparent support structure 60. This tumbling motion exposes the surfaces of the clothing item to the UV irradiance in the tunnel shaped enclosure 10.

Embodiments with the transparent support structure 60 are for disinfecting solid objects. As with all embodiments of the invention, minimizing leakage of UV rays is important. The preferred method to allow objects in and out of the tunnel shaped enclosure 10 such that they are supported by the transparent support structure 60 as the said objects move through the tunnel shaped enclosure 10. Various embodiments illustrating different variations of trap door 5 positions are illustrated in FIG. 4A to FIG. 4D. The trap doors 5 represent a section of the embodiment of the present invention 1 which creates a temporary opening to allow solid objects through wherein when these trap doors 5 are open, the UV radiation source 20 is switched off. In FIG. 4B to FIG. 4D, the trap door 5 situated at the top of the tunnel shaped enclosure 10 is open to allow objects to slide to the transparent support structure 60; the said trap door 5 quickly closes to minimize leakage of UV rays the moment the said object is supported by the transparent support structure 60; the outlet trap door 5 which is situated at the bottom or at the end of the tunnel shaped enclosure 10 opens to let the said object out of the tunnel shaped enclosure 10. The trap doors may be electronically actuated or spring loaded. In the embodiment for disinfecting large amount of clothing using a cylindrical transparent support structure 60, where trap doors are not used, the re-focusing reflectors 30 which are within the cylindrical transparent support structure 60 may be helical in shape so that clothing can enter inside the cylindrical transparent support structure 60 but UV light cannot transmit out of the tunnel shaped enclosure 10 via the cylindrical transparent support structure 60. The helical shaped re focusing reflectors 30 is illustrated in FIG. 4E.

The specular surface with convex protrusions is illustrated in FIG. 6. Parallel rays of UV are diffused into different directions by the convex protrusions on the specular surface. This illustrates possible alternatives to Lambertian reflection. These specular surfaces with convex protrusions may be used as a diffusing reflector 40 in a large embodiment of the present invention where porous PTFE may be cost prohibitive.

A specular surface without convex protrusions is preferred for the re-focusing reflector 30 so that all the UV rays can be re-directed back into the tunnel shaped enclosure 10. For the embodiment for disinfecting air, porous PTFE is preferred for the re-focusing reflector 30 because porous PTFE allows air to flow through whilst still providing very high reflectance. The single porous PTFE re-focusing reflector 30 can cover each entire opening of the tunnel shape enclosure 10 to re-direct UV rays back into the tunnel shaped enclosure 10.

Light emitting diodes (LED) are preferred to be used as the UV radiation source 20 in the present invention. UV LEDs are much smaller and operate at lower temperatures than other UV radiation sources. UV LEDs also only require very much lower voltages to operate compared to mercury based UV lamps.

Clark et al. (US8404186) states that if all surfaces have 90% Lambertian reflectance and total light leakage is less than 10%, the UV flux from a UV radiation source 20 is increased by a factor of between 5 and 100. In fact, even at 80% reflectivity of the diffusing reflectors 40 and 10% of the area inside the tunnel shaped enclosure 10 being non-reflective, this multiplying effect was noticed to be around 40 times in the present invention. Thus, the multiplying flux effect as claimed by Clark et al. (US8404186) to be only noticeable when the inner surfaces have reflectance greater than 90% is not true. What was also noticed is that the diffusing reflectors 40 also reflect the UV rays from at least one UV radiation source 20 such that the irradiation within the tunnel shaped enclosure 10 is homogeneous and uniform. What was also noticed that aluminium panels with convex protrusions was also able to accomplish diffused irradiation and the multiplying effect in the tunnel shaped enclosure 10.

The UV radiation source 20 is envisioned to radiate UV rays of wavelengths from as low as 170 nm to produce ozone as well as to disinfect. The UV radiation source 20 is also envisioned to radiate UV rays of wavelengths as high as 300 nm with the known peak for disinfection occurring at 265 nm.

While the invention has been shown and described with reference to the preferred embodiment thereof, it will be understood by those skilled in the art that various change in form and detail may be made therein without departing from the spirit and scope of the invention.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

Claims

1. An UV disinfection device (1) comprising : at least one tunnel shaped enclosure (10); at least one UV radiation source (20); at least one re-focusing reflector (30); at least one diffusing reflector (40); wherein the tunnel shaped enclosure (10) has at least one open end (12,14); wherein the at least one re-focusing reflector (30) is placed on at least one open end (12,14) of the tunnel shaped enclosure (10); wherein the at least one re-focusing reflector (30) is arranged such that any UV radiation originating from the UV radiation source (20) cannot directly transmit out of the tunnel shaped enclosure (10); wherein the at least one re-focusing reflector (30) reflects and re-directs at least the majority of UV radiation originating from the UV radiation source (20) towards at least one diffusing reflector (40) or towards at least one re-focusing reflector (30); wherein the diffusing reflector (40) is located on the inner surface of the tunnel shaped enclosure (10) and is used to reflect the rays from the UV radiation source (20) in a diffused pattern.

2. An UV disinfection device (1) according to Claim 1 wherein the diffusing reflector (40) or the re-focusing reflector (30) reflects at least 80% of UV rays.

3. An UV disinfection device (1) according to Claim 1 wherein the said diffusing reflector (40) has a surface which produces Lambertian reflectance.

4. An UV disinfection device (1) according to any of the preceding claims wherein at least one UV reflecting surface of the re-focusing reflector (30) or the diffusing reflector (40) or the combination comprises sintered PTFE.

5. An UV disinfection device (1) according to Claim 1 wherein the said diffusing reflector (40) has a surface with convex shaped protrusions. An UV disinfection device (1) according to Claim 5 wherein the surface of the said diffusing reflector (40) is specular. An UV disinfection device (1) according to any of the preceding claims further comprising : a conveyor system (50); wherein at least one part of the said conveyor system (50) is located within the tunnel shaped enclosure (10) and extends at least the majority of the length of the said the tunnel shaped enclosure (10); wherein at least the part of the said conveyor system (50) is inside the tunnel shaped enclosure (10). An UV disinfection device (1) according to any of the preceding claims further comprising : a transparent support structure (60); wherein transparent support structure (60) is at least partly located within the tunnel shaped enclosure (10) and extends to at least the majority of the length of the said the tunnel shaped enclosure (10); wherein the transparent support structure (60) supports the objects being disinfected and keeps the said objects from touching any other part of the UV disinfection device (1); wherein UV rays originating from the UV radiation source (20) can easily penetrate through the transparent support structure (60). An UV disinfection device (1) according to any of the preceding claims further comprising: at least one hydrophobic filter (70); wherein the said hydrophobic filter (70) is disposed in the tunnel shaped enclosure

(10) and covers the entire cross section of the tunnel shaped enclosure (10); wherein the said hydrophobic filter (70) has high UV reflectance; wherein the said hydrophobic filter (70) is porous. - 16 -

10. An UV disinfection device (1) according to any of the preceding claims wherein the UV radiation source (20) emits UV rays of a wavelength between 170 nm and 300 nm. 11. An UV disinfection device (1) according to any of the preceding claims wherein at least one end of the tunnel shaped enclosure (10) is connected to an external system.

12. An UV disinfection device (1) according to any of the preceding claims wherein there is at least a section (5) of the UV disinfection device (1) which can open and close to provide a temporary opening to allow objects to enter the said UV disinfection device (1).

13. An UV disinfection device (1) according to any of the preceding claims wherein the UV radiation source (20) comprises at least one light emitting diode.