DESC:FIELD OF INVENTION
The invention relates to a lighting device comprising of light emitting diode (LED) capable forcontinuous microbial disinfection and to a method of continuous disinfection of microbes (pathogens) from such a lighting device.
BACKGROUND ART
In present times, health, comfort and convenience have become the trend of modern homes. Photocatalytic degradation of organic pollutants / pathogens is a current concern for the treatment of pollution by means of disinfection. It can efficiently and environmentally degrade the volatile organic compounds with mal-odours into clean substances up to certain extent. However, althoughthe photocatalytic method has been confirmed and applied in the laboratory and some industrial fields, the photocatalytic device for home use still needs to be improved.
Indoor air quality is becoming an important public health concern as more than 70% of the time is spent indoors whether in house, office, school or colleges. It has been estimated that one third of indoor air quality (IAQ) complaints may be due to microbial contamination (Pope et al.., 1993) and exposure to these may cause allergies, respiratory and immune toxic diseases (Douwes et al., 2003). Bacteria, fungi, viruses, protozoans and microscopic animals have been linked to poor indoor air quality (Fabian et al., 2005).
In a study conducted in Rajasthan, the concentrations of air borne bacteria ranged from 198-347 cfu/m3, with peak values in September and lowest in April. The most common bacteria isolated were Gram positive which accounted for 47% of the total airborne bacterial count, most prevailing being Staphylococcus aureus (KavitaNaruka et al., 2013). The results of another study conducted in Uttarakhand showed that the indoor air of rural residential houses of Uttarakhand contained microbes and fungi that could cause important health problems such as allergies, rhinitis and chronic fatigue (Manisha Joshi et al., 2013).
Indoor microbial air flora is a cause of tremendous health concern in developing countries. Several allergic and infective diseases are linked to poor microbiological quality of indoor air in hospitals like Bronchopulmonary aspergillosis, sick building syndrome, and pneumonia (Sayan Bhattacharyya et al., (2015).
There are many techniques that can be used to kill bacteria in the air, such as chemical sterilization, sampling sterilization, and traditional low-pressure mercury lamp UV sterilization. Chemical sterilization technology uses chemical reagents to sterilize. Chemical reagents tend to remain on the surface of objects. The harmful substances generated are not easily degraded, posing potential harm to the human body and the environment. Ozone sterilization technology uses high voltage to stimulate air discharge to generate ozone. Ozone destroys the structure of the microbial membrane by the oxidation of oxygen atoms to achieve bactericidal action; the principle of ultraviolet bactericidal is that the energy of ultraviolet photons is absorbed by the base pairs in the DNA, causing the genetic material to mutate, causing the bacteria to die or not to breed. Thereby achieving the purpose ofsterilization is satisfied. It can be seen that the first two methods are not suitable for air sterilization in the home environment, and the ultraviolet sterilization can realize the sterilization function in the closed space such as the bathroom and the kitchen under the control. A commonly used ultraviolet light source is a low-pressure mercury lamp that uses low-pressure mercury vapour discharge to generate ultraviolet radiation. However, there are some shortcomings in the use of low-pressure mercury lamps in the home. First, the mercury of the low-pressure mercury lamp is a heavy metal. If its leaking from inside of the lamp, it will be harmful to the human body. After the glass tube is damaged, it is not conducive to repair and maintenance. Second, low- pressure, mercury lamps have a short service life and high energy consumption, which is not conducive to widespread promotion and application.
Therefore, provided herein are systems and methods for the disinfection and purification of environment using a light-emitting diode (LED) light source. In one embodiment, for example, there is provided a fluid flow conduit having an LED light source and a photo-catalytic material disposed therein. The LED light source emits ultraviolet light with a peak wavelength below 400 nm. In operation, the photo-catalytic material absorbs the ultraviolet light from the LED light source, and releases free radicals into the fluid. The free radicals then degrade organic substances (e.g., bacteria) in the fluid.
In the prior art an US application US 2008/0305004 A1 discloses inactivation of gram-positive bacteria, The specification discuss a method for inactivating medically important Gram-positive bacteria including Methicillin-resistant Staphylococcus aureus (MRSA), Coagulase-Negative Staphylococcus (CONS), Streptococcus, Enterococcus and Clostridium species, comprising exposure to visible light, and in particular light within the wavelength range 400-500 nm.
In another prior art, an US application US 2010/0246169 A1, discloses a lighting device with at least one first-element that emits visible light at a wavelength and irradiance sufficient to inactivate one or more pathogenic bacterial species, and at least one second element that emits light of one or more longer wave-lengths to that of the first-element. The at least one second element has a higherilluminance than that of the at least one inactivating element or component.
In another prior art, an US application US 2016/0030610 A1, discloses a light fixture. The light fixture includes at least one first light source that emits at a peak wavelength in a range of approximately 380 run to approximately 420 nm and at least one second light source that emits at a different peak wavelength, wherein a combined light output of the at least one first light source and the at least one second light source emits a coloured light that is perceived as white light. The white light is defined by having a colour rendering index (CRI) value of more than approximately50. The at least one second light source that emits at a different peak wavelength consists of an x-y coordinate on an International Commission on Illumination (CIE)1931 x-y colour space diagram above a black body curve within a bounded area defined by a first line of approximately y=2.23989x-0.382773 and a second line of approximately y=l.l55lx-0.195082. The combined light output has a proportion of spectral energy measured in the approximately 380 nm to approximately 420 mn range of greater than approximately 20%.
In another prior art, an US application US 2017/0006685 A1 discloses a method of automatically calibrating a luminaire including at least one light emitting diode (LED) engine, the LED engine including a plurality of LEDs and a controller for driving the at least one LED engine. The method comprises acquiring an image of light emitted from each LED of the LED engine, first determining whether each LED has a predetermined intensity for a colour of the LED, first adjusting each LED that does not have the predetermined intensity to have the predetermined intensity for the colour of the LED, measuring, by a spectrometer, a colour spectrum of a combined light of the LED engine, the colour spectrum including a plurality of measured colour spectrums, second determining whether a variation exists between each of the plurality of measured colour spectrums and a predetermined colour spectrum of a control data unit, and second adjusting at least one LED to correct variation.
In yet another prior art, a PCT publication WO 2017/009534 Al, discloses a light emitting diode (LED) structure, a lighting fixture and a method of providing white light illumination. The LED structure comprises: a substrate; a light emitting area defined on the substrate as a cavity; a first type of light emitting semiconductor source with bactericidal characteristics mounted in the cavity; a second type of light emitting semiconductor source mounted in the cavity with ability to excite a wavelength conversion material to generate white light; and the wavelength conversion materiallayer formed on top of the light emitting semiconductor sources. The invention enables disinfection by a lighting source or a luminaire visibly apparent to human as a white light source that is neither harmful to a human nor creates discomfort.
In yet another prior art, a PCT publication WO 2017/019933 A1, discloses a device which inactivates microorganisms. The device includes a light emitter and at least one light-converting material arranged to convert at least a portion of light from the light emitter. Any light emitted from the light emitter and converted light emitted from the at least one light-converting material mixes to form a combined light, the combined light having a proportion of spectral energy measured in an approximately380 nm to approximately 420 nm range of greater than approximately 20 percent. In another embodiment, the device includes a light emitter configured to emit light with wavelengths in a range of 380 to 420 nm, and at least one light-converting material including at least one optical brightener and configured to emit a second light. The first light exiting the device and the second light exiting the device mix to form a combined light, the combined light being white.
SUMMARY OF INVENTION
Based on this background it was an object of the present invention to provide a lighting device that is comparatively easy to produce, robust and configured to generate a broad, particularly white emission spectrum capable of microbial disinfection.
The lighting device according to the present invention comprises the following components:
a plurality of first light source LED’s that emits light at plurality of wavelengths in visible spectrum; at least one second light source LED that emits light at a wavelength shorter than that of first source; a wavelength converter for converting light emitted by the second light source into a different wavelength. The wavelengthconverter may particularly comprise a luminescent material that is excited by light coming from the light source and that re-emits the absorbed energy as light of a different wavelength.
In an embodiment, there is provided an optical component for redirecting light emitted by the light source and/or by the converter into a desired direction, for example by reflection or refraction, wherein the converter element / material is mechanically carried by said optical component.
In another embodiment, the said converter and the optical component are combined into one mechanically linked, stable structure. Also this structure can be fabricated separately from the total lighting device, allowing an optimal supply chain and a means to optimize fabrication yield by pre-testing this part.
Therefore such as herein described, there is provided a lighting device comprising: a plurality of first light source LED’s that emits light at plurality of wavelengths in visible spectrum; at least one second light source LED that emits light at a wavelength shorter than that of first source sufficient enough for continuous microbial disinfection; a diffuser or optical element configured for diffusing the intensity of the light source LED’s; wherein the said at least one second light source LED is driven by current of equal to or less than that of the plurality of first light source LED’s that emit visible spectrum.
Also described herein, there is provided a method of lighting a space, comprising: generating, from a plurality of first light source LED’s, light for illumination of the space light, at plurality of wavelengths in visible spectrum; generating, from at least one second light source LED, at a wavelength shorter than that of visible light sufficient enough for continuous microbial disinfection ; diffusing the generated light from the said LED’s; switching the said first light source LED’s vide at least one switching means; outputting, via a lighting device, the diffused light, wherein the said at least one second light source LED is driven by current of equal to or less than that of the plurality of first light source LED’s that emit visible spectrum.
In another embodiment, the lighting device is preferably capable to emit white light, particularly with a correlated colour temperature (CCT) in the range of 5600K. The emission of a white spectrum is achieved by a proper choice of light source and wavelength change material e.g. Phosphor material, any rare earth element or artificial element.There are different ways to couple the Phosphor to the optical component. In one preferred variant, this is achieved via andeposition or coating. The optical component viz a lens or a reflector and the diffuser are made available over the LED’s.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying figures, where like reference numerals refer to identical or functionally similar elements throughout the separate views, together with the detailed description below, are incorporated in and form part of the specification, and serve to further illustrate embodiments of concepts that include the claimed embodiments, and explain various principles and advantages of those embodiments.
FIG. 1 illustrates a schematic diagram of a lighting system constructed in accordance with the teachings of the present disclosure and employed in an environment susceptible to the transmission of pathogens in accordance with the present invention;
FIG. 2 A illustrates a schematic diagram of a lighting system with internal parts in accordance with the present invention;
FIG. 2 B illustrates a plan view of one exemplary version of the lighting device ofFIG. 2A in accordance with the present invention;
FIG. 3 illustrates a cross-sectional diagram of a lighting system in accordance with the present invention;
FIG. 4, illustrates the effect of lighting device on pathogens before and after treatment with respect to time duration in accordance with the present invention;
FIG. 5, illustrates the effect of lighting device on pathogens before and after treatment with respect to time duration along with switching OFF lighting devicein accordance with the present invention;
FIG. 6, illustrates the Spectrum diagram of lighting devicein accordance with the present invention;
FIG. 7, illustrates the graphical representation of effect of lighting device with respect to time on different pathogens (microbes)in accordance with the present invention;
FIG. 8, illustrates the graphical representation of percentage reduction of microbial at different locations and concentrationin accordance with the present invention;
FIG. 9, illustrates the graphical representation of percentage reduction of different microbes with different testing methodsin accordance with the present invention;
FIG. 10, illustrates the graphical representation of irradiance in accordance with the present invention.
DETAILED DESCRIPTION OF THE INVENTION
A lighting device, as an example of LED bulb, shown in FIG 1, comprising: a plurality of first light source LED’s (6) that emits light at plurality of wavelengths in visible spectrum; at least one second light source LED (7) that emits light at a wavelength shorter than that of visible light first source (6) sufficient enough for continuous microbial disinfection; a diffuser (1) or optical element configured for diffusing the intensity of the light source LED’s; wherein the said at least one second light source LED (7) is driven by current of equal to or less than that of the plurality of first light source LED’s (6) that emit visible spectrum.
FIG. 1 & FIG 2 which shows examples of a possible configuration for a lighting device that is operable to inactivate one or more microbial or potentially pathogenic microbial, such as E. Coli, yeast and mold, Staphylococcus aureus. The configuration can be of many types including tubelight, Chandelier, Ceiling mounted fixtures, Wall-mounted fixtures, Traditional recessed fixtures and/or Downlights, Track light, Floor lamp, Table lamp etc.Any chosen configuration is made up of a plurality of lights (6), typically LEDs, with a Wavelengthcomponent in the range between 400 nm and 420 nm, for inactivating microbial and a plurality of lights (7), again typically LEDs, that emit light that is White or a shade of White or light of colours outside the 400-420 nm range to improve and eliminate any discomfort that might be experienced from the 405-nm light alone. The elements can be arranged on a single substrate in any desired pattern for example square (5), as shown in FIGS. 2(a) and 2(b).
The lighting device, as shown in FIG 1 & 2, wherein the plurality of first light source LED’s (6) emits light at a peak wavelength in the range of approximately 400nm to approximately 700nm in visible spectrum. Similarly, at least one second light source emits at a peak wavelength in the range of approximately 400nm to approximately 420nm. The diffused light comprises a CRI value of more than 70.
The lighting device with at least one second light source LED (7) emits light in visible spectrum at a wavelength and intensity sufficient to inactivate one or more pathogenic microbial species in the air and on contact surfaces and materials.
In the lighting device at least one second light source LED (7) is covered with optical element and preferably lens (not shown). Also, at least one second light source LED (7) is activated with wavelength change material (Not shown) and the said diffuser (1) or optical element is selected from a group of materials from different Engineering plastic materials like PC, acrylic, PP, etc. In the lighting device, wherein the said wavelength change material as converter is selected from Phosphor.
A lighting device also comprises of Diffuser (1), Heat Sink housing (2) and B22 mounting (3). The configuration may change in other form of light like tubelights. The said heat sink housing (2) is fixed or mounted on B22 mounting. Similarly, said Diffuser (1) is mounted inside the heat sink housing (2) and fixed on heat sink (4) of the heat sink housing(2). The diffuser is used to diffuse the light for uniform luminousin the surroundings. The heat sink housing is provided to dissipate the heat generated inside the lighting system.
The said Heat Sink housing (2) comprises a MCPCB (5) which is mounted on heat sink housing (2) through a plurality of screw. The said MCPCB (5) comprises a plurality of first light source LED’s (6) that emits light at plurality of wavelengths in visible spectrum; and at least one second light source LED (7) that emits light at a wavelength shorter than that of visible light first source (6) sufficient enough for continuous Microbial disinfection in some pattern. Both types of LEDs are mounted on the MCPCB (Metal Core printed circuit board) in some pattern.
The wavelength change material will be used in another embodiment which comprises a lens and / or reflectors above the both types of LEDs. The wavelength changing material will be used on the top of the lens to change the wavelength of Second light source LEDs. The material can be placed in many ways such as provided on tip of the lens.
In FIG 3, shows a cross-sectional view of a lighting system shows Diffuser (1), HeatSink (4), Heat Sink Housing (2), Driver (8) and B22 Mounting (3).
When we insert the lighting system inside the holder, then Current will flow to LEDs (6) and (7) through wires to drivers and drivers to LEDs (6 & 7). After energizing the LEDs, both types of LEDs will Glow. First light source LED’s will give white light which is required to illuminate the ambient. When Second light source LED’s with shorter wavelength will glow, In an embodiment, the energizing circuitry of the first light source and second light source are different. Therefore the switching of the first and second light source can be controlled as per the disinfection and lighting needs. A person skilled in the art will be able to appreciate the need of the control in switching of the different light sources for the purpose of disinfection and lighting or both. TheSwitching is used to enable user to use system as per requirement. There may be 3 types of combination, 1. Only second LED (7) is on 2. Only first LED (6) is on 3. Both LEDS are on. For example, if we want to use it for washroom where, human interaction is less, we can only use option 1.
The lighting fixture can be used to simultaneously illuminate and decontaminate any area, for example the inside of an enclosure. The elements are arranged so that the integrated output of the device appears as white light a shade of white or a colour that is non-disturbing to personnel. This avoids the irritation that some people experience when exposed to light in the 400 nm to 420 nm range. The output of the light is such as to provide sufficient irradiance to inactivate infection-producing microbial over a surface area of the order of square meters, as well as in the surrounding air.
In a preferred embodiment, the microbial-inactivating LEDs produce light in a narrow wavelength range centered on 405 nm. Light in this narrowwavelength range photo-excites intracellular molecules inducing the production of free-radical molecules, such as the highly reactive singlet oxygen, within the microbial cells. The process occurs with maximum efficiency at 405 nm and leads ultimately to irreversible inactivation of microbial cells. The LED lighting device of the invention can take different forms if it includes the necessary active wavelength component with sufficient irradiance and its net light intensity is not disturbing to the eyes. The said lighting device includes a switching means (not shown) configured for switching the plurality of first light source LED’s (6).
A lighting device herein referred comprises of a plurality of first light source LED’s that emits light at plurality of wavelengths in visible spectrum; at least one second light source LED that emits light at a wavelength shorter than that of visible light first source sufficient enough for continuous microbial disinfection, A diffuser or optical element configured for diffusing the intensity of the light source LED’s. At least one switching means configured for switching the said first light source LED’s, wherein the said at least one second light source LED is driven by current of equal to or less than that of the plurality of first light source LED’s that emit visible spectrum. In the said lighting device, the said plurality of first light source LED’s emits at a peak wavelength in the range of approximately 400nm to approximately 700nm. The said at least one second light source emits at a peak wavelength in the range of approximately 400nm to approximately 420 nm. The lighting device comprising diffused light comprises a CRI value of more than 70. The lighting device with at least one second light source LED emits light in visible spectrum at a wavelength and intensity sufficient to inactivate one or more pathogenic microbial species in the air and on contact surfaces and materials. The said lighting device with at least one second light source LED is covered with lens and with at least one second light source LED is activated with wavelength change material. The lighting device, wherein the said diffuser or optical element is selected from a group of materials from different Engineering plastic materials like PC, acrylic, PP, PMMA etc. The said lighting device, wherein the said wavelength changes material is selected from Phosphor. The lighting device, wherein the said switching means includes remote wireless enabled switching and / or manual switching. Said the lighting device may also comprises another switching means which is responsive to detection of a person, detection of movement and detection of a change in an environment, such as to the opening or closure of a door.
The present disclosure also relates to a method of lighting a space, comprising steps like generating, from a plurality of first light source LED’s, light for illumination of the space light, at a plurality of wavelengths in visible spectrum; generating, from at least one second light source LED, at a wavelength shorter than that of visible light sufficient enough for continuous microbial disinfection. Then diffusing the generated light from the said first and second light source LED’s and thereafter outputting, via a lighting device, the even diffused light, wherein the said at least one second light source LED is driven by current of equal to or less than that of the plurality of first light source LED’s that emit visible spectrum.
In the said method, the plurality of first light source LED’s emits at a peak wavelength in the range of approximately 400 nm to approximately 700 nm, and at least one second light source emits at a peak wavelength in the range of approximately 400 nm to approximately 420 nm. The said method includes a diffused light comprises a CRI value of more than 70. The CRI value greater than 70 enables human eye to distinguish between different colours. To maintain the CRI 70 this system is designed such a way that cluster of LED will produce the CRI more than 70.
In the said method, the at least one second light source LED emits light in visible spectrum at a wavelength and intensity sufficient to inactivate one or more pathogenic microbial species in the air and on contact surfaces and materials. The said method comprises at least one second light source LED is covered with lens and at least one second light source LED is activated with wavelength change material. Also, the method comprises the said diffuser or optical element is selected from a group of materials from different Engineering plastic materials like PC, acrylic, PMMA, PP, etc. the said method comprises the said wavelength change material is selected from Phosphor.
In the said method, the plurality of first light source LED’s emits at a peak wavelength in the range of approximately 400 nm to approximately 700 nm and at least one second light source emits at a peak wavelength in the range of approximately 400 nm to approximately 420 nm. Also, the said having the diffused light comprises a CRI value of more than 70.The method with at least one second light source LED emits light in visible spectrum at a wavelength and intensity sufficient to inactivate one or more pathogenic microbial species in the air and on contact surfaces and materials.
Further, the at least one second light source LED is covered with lens and at least one second light source LED is activated with wavelength change material. Also, the said diffuser or optical element is selected from a group of materials from different Engineering plastic materials like PC, acrylic, PMMA, PP, etc and the said wavelength change material is selected from Phosphor.
The method also includes switching means which includes remote wireless enabled switching and / or manual switching wherein the switching means is responsive to detection of a person, detection of movement and detection of a change in an environment, such as to the opening or closure of a door.The lighting device also may include remote monitoring and control means using IOT.
During the experimentation and as an example, FIG 4 to 5, shows a reduction in microbes count by using the lighting device before and after the treatment. In Fig4, the effect of lighting device on pathogens before and after treatment with respect to time duration is shown. The figure clearly depicts the reduction in microbestolarge extent during exposure. Further Fig 5 represents the effect of lighting device on microbes even after switching OFF lighting device after 2 hours of exposure and shows further reduction in microbial count.
In FIG. 6, the Spectrum diagram of lighting device which indicates the changes in irradiance with respect to wavelength. The irradiance peak around 405nm causes the microbial reduction to large extent and beyond 420 nm it gives illuminance. The irradiance peak around 405 nm causes the microbial reduction by the second light source LED (7) to large extent and beyond 420 nm it gives luminance. The peak irradiance value is highest at 460nm, which belongs to the first light source LED’s (6). This graph is for the complete device which consists of First light source LED (6) second light source LED (7). Antimicrobial effect is not only depending on irradiance but also on a particular wavelength i.e. 405nm.
The newly developed lighting device is cost effective and provide sufficient illuminance and with antimicrobial effect. The High irradiance peak for 460nm is also desired to provide sufficient illuminance. The same can be visualized in In FIG. 10 which show the Spectrum diagram of a different lighting device which indicates the changes in irradiance with respect to wavelength.
In another embodiment, IOT intelligent lighting control method based architecture, is provided through which the position of the person on the area in which a presenceheat sensor transmits the control command through the communication network, to control the switching and further controlling the brightness of disclosed LED lighting system a region or a particular area.
During experimentation, the inventors hadtried and achievedsurprising results with different combination of both types of LEDs (4 and 5), to achieve the sufficient illuminance, antibacterial effect, and cost-effectiveness.
Therefore such as herein describedthe inventors havedeveloped the device 3 as referred in fig 6 and 10which gives the best results with economic significance. Device 4 and 5 may give better results, but costly and device 1 and 2 will not provide the sufficient luminance and antimicrobial effect.
FIG 7, shows the percentage reduction of different microbials viz. (TPC, YMC, S. aureus, and E. Coli),with respect to time. The graphillustrates that as time increases percentage reduction of microbials also increases. Even after switching OFF the device, reduction is continuous.Also Fig 8, shows the percentage reduction of different microbials (TPC, YMC, S.aureus, and E. Coli) with respect to different locations and different initial concentration of microbials. Different concentration of microbials like log101, log102, log103, log104, are taken into the consideration at three different locations A, B and C. The percentage reduction in microbial count is better at location A. Location A is closed (1. 7 meter) Lighting Device, whereas Location B and C is 2 meter and 4 meter far from lighting device respectively.Also Fig 9, shows the percentage reduction of different microbials (TPC, YMC, S. aureus, and E. Coli) with respect to different test methods. SWAB method shows better performance with respect to Air sampling and Expose plate method. Moreover SWAB method is widely used in different industries for bacteria reduction like soap,sanitiser etc.
Although the foregoing description of the present invention has been shown and described with reference to particular embodiments and applications thereof, it has been presented for purposes of illustration by way of examples and description and is not intended to be exhaustive or to limit the invention to the particular embodiments and applications disclosed. The particular embodiments and applications were chosen and described to provide the best illustration of the principles of the invention and its practical application to thereby enable one of ordinary skill in the art to utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated. All such changes, modifications, variations, and alterations should therefore be seen as being within the scope of the present invention as determined by the appended claims when interpreted in accordance with the breadth to which they are fairly, legally, and equitably entitled.
Some prior art references (Citations):-
Sayan Bhattacharyya, AsimSarfraz and Nitish Jaiswal 2015, Hospital indoor air microbial quality: Importance and monitoring. Advances in applied science research,6(2):154-156
Manisha Joshi, R. K Srivastava (2013). Identification of indoor airborne microorganisms in residential rural houses in Uttarakhand, India -International Journal of current Microbiology and Applied Sciences,6:146-152
Fabian, M.P., Miller, S.L., REsponen, T.and Hernandez (2005). Ambient bioaerosol indices for indoor air quality assessments of flood reclamation. Aerosol Science,36:763-783
KavitaNaruka., Jyoti Gaur., (2013). Microbial air contamination in a school. International Journal of Current Microbiology and Applied Sciences,12: 404-410
Douwes, J., P. Thorne, N. Pearce and Heederik D. (2003). Bio Aerosol Health effects and exposure assessment: Progress and prospects. Ann occup Hyg.47:187-200
Pope, A.M., R. Patterson and Burge, H (1993) Indoor Allergens, National Academy Press, Washington, DC.

,CLAIMS:
1. A lighting device comprising:
a plurality of first light source LED’s that emits light at plurality of wavelengths in visible spectrum;
at least one second light source LED that emits light at a wavelength shorter than that of first source sufficient enough for continuous microbial disinfection;
a diffuser or optical element configured for diffusing the intensity of the light source LED’s; wherein the said at least one second light source LED is driven by current of equal to or less than that of the plurality of first light source LED’s that emit visible spectrum.
2. The lighting device of claim 1, wherein the plurality of first light source LED’s emits at a peak wavelength in the range of approximately 400 nm to approximately 700 nm.
3. The lighting device of claim 1, wherein the at least one second light source emits at a peak wavelength in the range of approximately 400 nm to approximately 420 nm.
4. The lighting device of claim 1, wherein with at least one second light source LED emits light in visible spectrum at a wavelength and intensity sufficient to inactivate one or more pathogenic microbial species in the air and on contact surfaces and materials.
5. A lighting device comprising: a plurality of first light source LED’s that emits light at plurality of wavelengths in visible spectrum; at least one second light source LED that emits light at a wavelength shorter than that of first source sufficient enough for continuous microbial disinfection; a diffuser or optical element configured for diffusing the intensity of the light source LED’s; at least one switching means configured for switching the said first light source LED’s; wherein the said at least one second light source LED is driven by current of equal to or less than that of the plurality of first light source LED’s that emit visible spectrum.
6. The lighting device of any of the preceding claims, wherein the diffused light comprises a CRI value of more than 70.
7. The lighting device of any of the preceding claims, wherein with at least one second light source LED emits light in visible spectrum at a wavelength and intensity sufficient to inactivate one or more pathogenic microbial species in the air and on contact surfaces and materials.
8. The lighting device of any of the preceding claims, wherein with at least one second light source LED and / or first light source LED are covered with optical elements like lens, reflector.
9. The lighting device any of the preceding claims, wherein with at least one second light source LED is activated with wavelength change material.
10. The lighting device of any of the preceding claims, wherein the said diffuser or optical element is selected from a group of materials from different Engineering plastic materials like PC, PMMA,etc
11. The lighting device of any of the preceding claims, wherein the said wavelength change material is selected from Phosphor, rare earth elements or artificial element.
12. The lighting device of claim 5 wherein the said switching means includes remote wireless enabled switching and / or manual switching.
13. The lighting device of claim 12 wherein the switching means is responsive to detection of a person.
14. The lighting device of claim 13 wherein the switching means is responsive to detection of movement.
15. The lighting device of claim 14, wherein the switching means is responsive to detection of a change in an environment, such as to the opening or closure of a door.
16. A method of lighting a space, comprising the steps of :
generating, from a plurality of first light source LED’s, light for illumination of the space light, at plurality of wavelengths in visible spectrum;
generating, from at least one second light source LED, at a wavelength shorter than that of visible light sufficient enough for continuous microbial disinfection;
diffusing the generated light from the said LED’s; and
outputting, via the said lighting device, the diffused light, wherein the said at least one second light source LED is driven by current of equal to or less than that of the plurality of first light source LED’s that emit visible spectrum.
17. The method of claim 24, wherein the plurality of first light source LED’s emits at a peak wavelength in the range of approximately 400 nm to approximately 700 nm.
18. The method of claim 24, wherein the at least one second light source emits at a peak wavelength in the range of approximately 400 nm to approximately 420 nm.
19. A method of lighting a space, comprising: generating, from a plurality of first light source LED’s, light for illumination of the space light, at plurality of wavelengths in visible spectrum; generating, from at least one second light source LED, at a wavelength shorter than that of visible light sufficient enough for continuous microbial disinfection ; diffusing the generated light from the said LED’s; switching the said first light source LED’s vide at least one switching means; outputting, via a lighting device, the diffused light, wherein the said at least one second light source LED is driven by current of equal to or less than that of the plurality of first light source LED’s that emit visible spectrum.
20. The method of claim 16 or 19, wherein the diffused light comprises a CRI value of more than equal to 70.
21. The method of claim 16 or 19, wherein with at least one second light source LED emits light in visible spectrum at a wavelength and intensity sufficient to inactivate one or more pathogenic microbial species in the air and on contact surfaces and materials.
22. The method of claim 16 or 19, wherein with at least one first light source or one second light source LED are covered with optical element like lens or reflector.
23. The method of claim 16 or 19, wherein with at least one second light source LED is activated with wavelength change material.
24. The method of claim 16 or 19, wherein the said diffuser or optical element is selected from a group of materials from different Engineering plastic materials like PC, PMMA, etc.
25. The method of claim 16 or 19, wherein the said wavelength change material is selected from Phosphor, any other rare earth element or artificial element.
26. The method of claim 19, wherein the said switching means includes remote wireless enabled switching and / or manual switching.
27. The method of claim 26, wherein the switching means is responsive to detection of a person.
28. The method of claim 27, wherein the switching means is responsive to detection of movement.
29. The method of claim 28, wherein the switching means is responsive to detection of a change in an environment, such as to the opening or closure of a door.
30. The lighting device of any of the preceding claims, wherein the lighting device includes remote monitoring and control means using IOT.
31. The method of lighting a space of any of the preceding claims, wherein the lighting device includes remote monitoring and control means using IOT.