Electrical filter structure

Abstract

This publication discloses a filter unit connectable to a mobile communication device including a fan for generating an air flow inside the filter unit, electrodes covered with a photo catalytic material like TiO.sub.2 in the air flow, UV-LEDs illuminating the electrodes, and outlet for the air flow directed in direction of user of filter unit.

Claims

1. A mobile filter unit comprising: a mobile communication device, and a filter unit connected to the mobile communication device, wherein the filter unit comprises: a fan for generating an air flow from behind of the mobile communication device, a high voltage unit for charging the air flow and its particles, TiO.sub.2-covered electrodes in the air flow connected to opposite polarity than the high voltage unit, UV-LEDs illuminating the electrodes, and an outlet for the air flow directed in direction of user of the mobile communication device.

2. The mobile filter unit in accordance with claim 1, wherein the electrodes are a filter consumable filter unit and the electrodes are from aluminium, plastic or other suitable conductive materials and are forming a low pressure drop form like honeycomb, mesh, fins, pleated etc.

3. The mobile filter unit in accordance with claim 1, further comprising a removable particle filter.

4. The mobile filter unit in accordance with claim 1, further comprising a magnetic connection between the filter unit and the mobile communication device.

5. The mobile filter unit in accordance with claim 1, further comprising a battery having connections both for charging from and loading to other devices.

6. The mobile filter unit in accordance with claim 1, further comprising a changeable filtration unit.

7. The mobile filter unit in accordance with claim 1, further comprising a folded filter material.

8. The mobile filter unit in accordance with claim 1, further comprising a slider for adjusting the direction of the output air flow.

9. A mobile filter unit connectable to a mobile communication device comprising: a fan for generating an air flow inside the filter unit, electrodes covered with a photo catalytic material like TiO.sub.2 in the air flow, UV-LEDs illuminating the electrodes, and an outlet for the air flow directed in direction of user of filter unit.

10. The mobile filter unit in accordance with claim 9, further comprising a high voltage unit for charging the air flow and its particles and electrodes covered with a photo catalytic material like TiO.sub.2 in the air flow and connected to a different voltage than the high voltage unit, preferably to opposite polarity than the high voltage unit.

11. The mobile filter unit in accordance with claim 9, wherein the electrodes are as filter consumable filter unit and the electrodes are from aluminium, plastic or other suitable conductive materials and are forming a low pressure drop form like honeycomb, mesh, fins, pleated etc.

12. The mobile filter unit in accordance with claim 9, further comprising a removable particle filter.

13. The mobile filter unit in accordance with claim 9, further comprising a magnetic connection between the filter unit and the mobile communication device.

14. The mobile filter unit in accordance with claim 9, further comprising a battery having connections both for charging from and to other devices like mobile phones.

15. The mobile filter unit in accordance with claim 9, further comprising a changeable filtration unit.

16. The mobile filter unit in accordance with claim 9, further comprising a folded filter material.

17. The mobile filter unit in accordance with claim 9, further comprising a slider for adjusting the direction and distribution of the output air flow.

18. The mobile filter unit in accordance with claim 9, further comprising magnets for attaching the filter unit to a communications device.

19. The mobile filter unit in accordance with claim 9, wherein the filter is wave formed and electrodes which are positioned substantially parallel to the direction of flow of the gas are equipped with ultraviolet light sources and covered with photo catalytic material like TiO.sub.2.

20. The mobile filter unit in accordance with claim 9, wherein brush like corona elements are used for charging incoming particles.

21. The mobile filter unit in accordance with claim 9, further comprising means for forcing the incoming air to contact TiO.sub.2 or other catalyst grounded or covered electrodes by using opposite polarity than high voltage used for charging the incoming air flow.

22. The mobile filter unit in accordance with claim 9, wherein in the removable filter element bottom and sides are from electrically conductive material and filter material is coated with TiO.sub.2, Ag or similar Nano catalyst material.

23. The mobile filter unit in accordance with claim 9, wherein the filter casing is from UVA penetrable plastic sheet having essentially uniform distribution for UV-A led light.

24. The mobile filter unit in accordance with claim 9, wherein the structures forming the filter casing are coated with TiO.sub.2, Ag or similar Nano catalyst material.

25. The mobile filter unit in accordance with claim 9, wherein it is equipped with CO.sub.2 sensor and means for adjusting the speed of fan based on the CO.sub.2 content such that the higher CO.sub.2 content corresponds to a higher fan speed.

26. The mobile filter unit in accordance with claim 9, wherein the filter case is connected to a second electric potential different to the potential of the charged particles and set substantially parallel to the direction of the airflow.

27. A filter casing for a mobile filter unit comprising: a housing with openings for air flow, and filter material inside the housing, wherein the housing is: at least partially transparent to UV-light, electrically conductive, and covered at least partially with photocatalytic material like TiO.sub.2, and the filter material is: covered at least partially with photocatalytic material like TiO.sub.2.

28. The filter casing in accordance with claim 27, wherein above the housing is positioned a paper sheet for dividing illumination and above this a UV-penetrable sheet acting as a case cover.

29. The filter casing in accordance with claim 27, wherein the filter material is two layered, one for particles and the other for gaseous material.

30. The filter casing in accordance with claim 27, wherein the housing is electrically connected to a desired potential when the casing is connected to a filter unit either by surface contact or by a connector.

Description

[0079] In the following, the invention is examined with the aid of examples and with reference to the accompanying drawings.

[0080] FIG. 1 shows a schematic diagram of one filter solution according to the prior art.

[0081] FIG. 2 shows a schematic diagram of a second filter according to the prior art.

[0082] FIG. 3 shows a schematic diagram of the filter solution according to the prior art.

[0083] FIG. 4 shows a filter solution according to the invention.

[0084] FIG. 5 shows the electrode element of FIG. 4.

[0085] FIG. 6 shows the charging unit according to the invention.

[0086] FIG. 7 shows as a block diagram one embodiment of the invention.

[0087] FIG. 8 shows as a cross sectional view one filter element in accordance with the invention.

[0088] FIG. 9 shows as a cross sectional view another filter element.

[0089] FIG. 10 shows as a cross sectional view another filter element in accordance with the invention.

[0090] FIG. 11 shows another embodiment of the charging unit of FIG. 5.

[0091] FIG. 12 shows a cross section of the charging unit of FIG. 11 positioned inside the filter bag unit in accordance with the invention.

[0092] FIG. 13 shows a filter bag unit in accordance with the invention.

[0093] FIG. 14 shows another charging unit in accordance with the invention.

[0094] FIG. 15 shows a filter construction where several charging units of FIG. 14 are combined together and combined with a filter construction.

[0095] FIG. 16 shows a filter construction of FIG. 15 where the filter unit is assembled to the charging unit.

[0096] FIG. 17 shows a cross section of FIG. 16.

[0097] FIG. 18 shows a more detailed view of FIG. 17.

[0098] FIG. 19 shows one connectable embodiment of the charging unit to form a construction shown in FIGS. 15 and 16 in accordance with the invention.

[0099] FIG. 20 shows details of the charging unit to form a construction shown in FIGS. 15 and 16 in accordance with the invention.

[0100] FIG. 21 shows mounting details of the charging unit to form a construction shown in FIGS. 15 and 16 in accordance with the invention.

[0101] FIG. 22 shows a back view of an embodiment of the invention where the filter unit is combined with a mobile phone.

[0102] FIG. 23 shows a side view of the embodiment of FIG. 22.

[0103] FIG. 24 shows a perspective view of an embodiment of the invention where the electrodes are formed of transparent, electrically conductive film like material.

[0104] FIG. 25 shows a detail of FIG. 24.

[0105] FIG. 26 shows a schematic presentation of the invention, where the TiO.sub.2 coating is placed outside the filter bags with UV-light sources.

[0106] FIG. 27 shows a practical embodiment of FIG. 26.

[0107] FIG. 28 shows a magnetic connection between a mobile phone and the air filter.

[0108] FIG. 29 shows a filter unit in accordance with the invention with a high voltage charging unit.

[0109] FIG. 30 shows a filter unit in accordance with the invention combined with a mobile phone.

[0110] FIG. 31 shows a partially sectioned view of filter unit in accordance with the invention.

[0111] FIG. 32 shows a filter unit of FIG. 31 in more detail.

[0112] FIGS. 33-34 show the air flow of filter units described in FIGS. 28-32.

[0113] FIGS. 35-38 show the structure of the removable particle filter casing in more detail.

[0114] In the following, the invention is examined with the aid of the following terms: [0115] 1 charging section [0116] 2 separation section, electrostatic filter [0117] 3 ion path [0118] 4 corona wire [0119] 5 positively charged particle [0120] 6 air flow [0121] 7 fibre filter [0122] 8 metal mesh [0123] 9 separation plate [0124] 10 charging unit [0125] 11 high voltage [0126] 12 fibre filter [0127] 13 activated carbon filter [0128] 14 positive metal electrode of the activated carbon filter or TiO.sub.2 covered electrodes [0129] 15 earthed electrode of the activated carbon filter [0130] 16 UV-light sources [0131] 17 corona brushes [0132] 18 Cover plate of the charging unit [0133] 19 High voltage unit [0134] 20 Corona strip [0135] 21 Corona strip insulators [0136] 22 Frame of the electrode unit [0137] 23 Wirings of the electrodes 14 and UV-light sources [0138] 24 Support poles for the filter bags 14 [0139] 25 Electrode unit [0140] 26 Filter bag unit [0141] 27 Particle filter media [0142] 28 Gas filter media [0143] 29 Filter mounting frame [0144] 30 Sub-filters [0145] 31 Grounding [0146] 32 UV-transformer [0147] 33 Positive voltage transformer [0148] 34 Positive voltage electrodes [0149] 35 Input for positive voltage [0150] 36 Protective grid in AHU solution [0151] 37 High voltage sockets [0152] 38 Corrugated filter media [0153] 39 Contactor for grounding [0154] 40 Contact for high voltage [0155] 41 Contact for high voltage [0156] 42 Fixed mounting rail [0157] 43 Adjustable mounting rail [0158] 44 Charging unit frame [0159] 45 Mobile communication device, mobile phone [0160] 46 Camera optics [0161] 47 portable filter unit 48 Removable particle filter casing [0162] 49 Transformer [0163] 50 High voltage unit [0164] 51 Fan [0165] 52 Support bar [0166] 53 Outlet for the air flow [0167] 54 Plug in [0168] 55 Plug [0169] 56 Particle sensor [0170] 57 CO.sub.2 sensor [0171] 58 Monitor unit [0172] 60 Filter cover (UV-a can pass) [0173] 61 Plastic sheet with dot matrix printing for spreading UV-illumination evenly to whole sheet [0174] 62 thin paper between plastic sheets [0175] 63 lid of filter material, transparent [0176] 64 folded filter material [0177] 65 main printed circuit board (PCB) [0178] 67 USB-A-port for using the unit 47 as a charger [0179] 68 micro-USB-port for charging the battery 72 [0180] 69 LED-indicator (on/off/filter change) [0181] 71 Magnets for attaching to the mobile device [0182] 72 Battery [0183] 73 intake grill [0184] 74 slider for adjusting the direction of the output air flow [0185] 75 intake chamber of the fan [0186] 76 output chamber of the fan [0187] 77 filter casing bottom [0188] 78 filter casing sides [0189] 79 carbon fibers for negative ion input [0190] 80 guiding pins for filter material 64

[0191] In accordance with one preferred embodiment of the invention in FIG. 4 is presented a combined filter 26 and electrode unit 25 mounted together. In operation the structure is surrounded from all sides by a ventilation duct and air flows from top to bottom in accordance with the arrow in the figure.

[0192] Electrodes 14 are positioned parallel to the air flow and covered with a suitable photo catalytic material like TiO.sub.2. The electrodes 14 are typically aluminium, also other metals or other electrically conductive material may be used. On these electrode plates are positioned UV-light sources 16 on both sides of the electrode. These light sources 16 are typically LED (Light emitting Diodes) light sources assembled on suitable substrate, in this case a longitudinal circuit board extending deep into the filter bag 15. Typically the light source elements are as long as the electrodes 14. On the other hand the electrodes 14 extend almost to the end of the filter bags 15. The ratio of the length of the electrode 14 to the length of the filter bag 15 is typically around 70%, advantageously in the range of 50-95%. Wiring 23 feeds energy to the light sources 16 and as well takes care of the grounding of the electrodes 14.

[0193] Using UV-C light LED lights are installed on both sides of electrode. The main target with UV-C radiation is to destroy DNA structure of the organic material captured to the filter media. UV-A and UV-B light can also be installed in both sides of electrodes and be mainly used for photocatalytic oxidation.

[0194] Using UV-A and UV-B led lights can also be installed inside between electrode plates (FIGS. 24-25) that must be then transparent enabling uv-light to penetrate through plates. These plates can have either honeycomb, mesh wire or nanostructure like graphene or other nano layer type structure to enhance surface area for TiO.sub.2 or other catalyst above flat plates. Only electrode plate's inner side against UV-light will not be coated with TiO.sub.2, all other surfaces (Electrode plates outer side and structures integrated in it) will be coated with anatase phase or combination of anatase and rutile phase of TiO.sub.2. Other catalyst can also be used. Amount of LED-light depends on the usage of the filter solution, distance to catalyst and PCO efficiency needed The efficiency of LED light is measured in lumens per watt, which refers to the total quantity of light the LED lamp produces per 1 W of energy. Efficiency=total lumen output/total power.

[0195] These light sources 16 are typically LED (Light emitting Diodes) light sources assembled on suitable substrate, in this case a longitudinal circuit board extending deep into the filter bag 15. Typically the light source elements are slightly shorter than electrodes 14. On the other hand the electrodes 14 extend almost to the end of the filter bags 15.

[0196] In one preferred embodiment of the invention the filter bag unit 26 (without the charging unit 25) is disposable, in other words the filter bags 15 will not be cleaned but replaced by a new unit when dirty. This saves essentially maintenance time and cost.

[0197] Photo catalytic material like TiO.sub.2 may also be positioned in the filter bags 15 with suitable process like with wet and dry methods. In the wet method, the nano-TiO.sub.2 in anatase phase of TiO.sub.2 is in liquid solution which is sprayed onto the substrate. In the dry method the anatase phase of TiO.sub.2 is in powder form and then led through the substrate material. Nano-coating methods such as spraying, dipping and ultra sound treating may be used.

[0198] First filter media to against UV-light source will be treated with photo catalyst and it can be: [0199] non woven activated carbon filter media [0200] electret filter material [0201] coarse filter material
combination and or mix of the filter material named above other filter material

[0202] In FIG. 5 can be seen an electrode unit 25 turned upside down such that and UV light sources 16 are visible. The electrodes 14 are positioned between support poles 24, which keep the elastic filter bags 15 in suitable form. The frame 22 may be e.g. plastic. As can be seen from the figure one preferred embodiment includes 8 electrodes 14 and correspondingly 8 filter bags 15. Of course the number of electrode/bag pairs can vary, typically in range of 4-12.

[0203] In accordance with FIG. 6 the charging unit 10 comprises a frame 44, which is typically aluminium. Inside of the frame 44 are positioned corona strips 20 equipped with brush like extensions 17 directed against the air flow. These extensions have activated carbon fibre brushes 17 on the top. In this way the first thing high voltage item the air flow meets are these carbon fibre brushes 17. By this feature wear of the corona elements can be minimized. In this solution there are two parallel electrically conductive corona strips 20 positioned such that each strip 20 is located about 25% of the total width W away from the inside of the frame 44, where W is the total width of the inside of the frame 44. The number of corona strips 20 increases if the inner cross section (face) of charging unit 10 increases. On the other hand each brush 17 has a limited area of influence and therefore a charging unit 10 (as well as the filter structure 2) with a larger cross section (face) needs more brushes 17.

[0204] The frame 44 is typically square, also rectangle form for the frame 44 is a possible form for the frame 44. High voltage is input to the to the corona strips 20 from high voltage unit 19 of the charging unit 10. The high voltage is typically negatively charged. The corona strips 20 are insulated from the frame 44 by insulators 21. During operation cover unit 18 will be placed into the frame 44.

[0205] In operation the charging unit 10 will be placed above the construction of FIG. 4 such that the incoming air will first meet the charging unit 10 and then electrode 25 and filter bag unit 26.

[0206] FIG. 7 shows an overall concept of the invention. The arrow shows the direction of the air flow. First in the air flow is the charging unit 10, next charging unit 10 and finally bag unit 26 with filter bags.

[0207] The above described filter construction is a new effective solution to purify particle and gaseous contaminants. This invention can be used as integrated air purifier when installed in ventilation system for purifying fresh-, re-circulated or exhaust air. It can also be installed inside a casing with fan and power supply as a stand-alone air purifier.

[0208] Invention can be used to replace regular filters used in Air Handling Units (AHU) having following functions: It will charge the air airflow thus enhance capturing efficiency for particles, it has photo catalytic oxidation function (PCO) as well as sterilizing ones too.

[0209] Inside filter bag's frame is installed for charging the airflow, high voltage unit (input 220-240 V, 50/60 Hz, output 12V or 24V with 6-15 kV) and for LED UV-light, electronic transformer (input 220-240 V, 50/60 Hz, output 12V).

[0210] Filter bag 15 has supporting poles 24 inside pockets where electrodes 14 (material can be varied) are positioned and are coated with a photo catalytic material like TiO.sub.2 that is photo catalytically active with UV-light (here can be used, based on purpose A, B or C-UV light or combination of lights. LED UV-lights 16 are connected to the electrodes 14 such that they are close to (0.5-20 mm) to the filter media.

[0211] The filter bags 15 and electrodes 14 can be electrically connected together with connectors, thus only one electric cable connection and earth cable connection is needed to one filter bag 15/electrode 14. When installing filterbags inside AHU, existing filter frame can be used without any changeonly 220/240 V and earth cable need to be connected.

[0212] In advantageous embodiments of the invention the invention includes filter bags 15, charger unit 10 and a photo catalytic element with UV-light sources 16 and photo catalytic material, e.g. TiO.sub.2. Further, the filter bags 15 are advantageously disposable.

[0213] In accordance with FIG. 8 in one preferred embodiment of the invention each bag filter element 15 of the bag unit 26 of FIG. 4 comprises of an aluminium electrode 14 extending to the bottom or almost to the bottom of the bag filter element 15. The electrode 14 is covered with photo catalytic material like TiO2 and also has UV-light sources 16 on both sides of the electrode. Advantageously the electrode 14 is grounded to earth potential. The incoming air is charged by high negative voltage by brushes 17 fed by high voltage unit 15 and the UV-lights 16 are fed by transformer 32 with low voltage. The bag filters 15 typically comprise at least two layers namely particle filter media 27 as inner structure for capturing small impurities in particle for and a gas filter media layer 28 as an outer structure for capturing gaseous materials. The gas filter media layer may be e.g. activated carbon. The media layers 27 and 28 may be combined together e.g. by ultrasonic welding. The bag like filters 15 are mounted in a filter mounting frame 29 side by side as can be seen from FIG. 4 in order to cover the complete inner cross section (face) of the filter structure 2. In this solution the inside of bag 27 may be alternatively covered with TiO.sub.2 or the TiO.sub.2 cover may be in both surfaces 27 and 14.

[0214] In accordance with FIG. 9 a basic solution is presented where such a filter structure 15 is used comprising multiple sub-filters 30 inside the main filter bag. Also here the filter 15 is mounted to filter mounting frame in the same way as in FIG. 4. In the incoming air is positioned charging unit with brushes 17 and grounding elements 31 like earthed metal plates. Here the charging unit may be assembled to existing filter structures.

[0215] FIG. 10 is a modification of FIG. 9 such that each filter element 15 has a designated photo catalytic element in front of them in the air flow path in form of UV-lights 16 and grounded metal plates 31 with photo catalytic material like TiO.sub.2. In addition the structure comprises charging brushes 17 isolated electrically from the grounding elements 31.

[0216] Anatase phase TiO2 band gap is 3.2 eV.

[0217] Installing LED based UV lamps are much cheaper but light density is low thus they must be installed nearby surfaces to be radiated.

[0218] This invention has very small initial investment cost and low running costs comparing the existing separate solution available in the market.

[0219] In FIGS. 11 and 12 are presented an embodiment where the electrode unit 25 is equipped with a positive electrode structure 34 for each of the electrodes 14 such that the tip of this electrode structure charges the insides of the filter bags 15 of FIG. 12 with positive charge of around 1 kV. The voltage depends on the material of the bag 15 as well as the mechanical properties of the tip of the electrode structure 34. These electrodes 34 are fed with a transformer 33, which gets its input from connector 35 of FIG. 12. The electrodes 14 are typically grounded and isolated from the positive electrodes 34. In FIG. 11 there are two rows of UV-light sources 16 on both sides of the electrodes 14. In accordance with the invention there could be even two additional rows of these UV-light sources 16 on both sides of the electrodes 14 positioned for example on the outer sides of the electrodes 14, in other words in the left and right sides of each electrode in FIG. 11 such that maximum area onside the filter bags 15 would be illuminated by the UV-light. These UV-light sources 16 are fed by UV-transformers 32. Also here the inside of the bag filters 15 may be covered with TiO.sub.2.

[0220] As can be seen from FIG. 12 the filter bags 15 may have two bags inside each other like in FIG. 8 however the inner bag must be at least partially conductive in order to charge it with positive voltage.

[0221] FIGS. 12 and 14 show also the corona brushes 17 for negative charging of the air flow.

[0222] The bags materials may be the following: [0223] Inner bag 27 (FIG. 8) [0224] Coarse filter, typically 250-500 g/m.sup.2) [0225] Outer bag 28 (FIG. 8) [0226] Fine filter, typically 100-250 g/m.sup.2

[0227] The referred classifications are based on EN799 standard can be found e.g. on web page:

http://apps.who.int/medicinedocs/en/d/Js14065e/12.html#Js14065e.12

[0228] Particulate matter in ISO 16890 describes a size fraction of the natural aerosol (liquid and solid particles) suspended in ambient air. The symbol ePMx describes the efficiency of an air cleaning device to particles with an optical diameter between 0,3 m and x m. The following particle size ranges are used in the ISO 16890 series for the listed efficiency values.

[0229] Optical particle diameter size ranges for the definition of the efficiencies, ePMx

TABLE-US-00001 Efficiency Size range, m ePM10 0.3 x 10 ePM2.5 0.3 x 2.5 ePM1 0.3 x 1

[0230] These materials may be impregnated for removal/adsorption/absorption of different gases, one for SO.sub.2 and the other for NO.sub.X.

[0231] The inner media bag 27, which can also be the only filter bag, can be impregnated by TiO.sub.2 for better photo catalytic oxidation function. It can also be impregnated against gases PCO is not effective enough. There are several alternatives for suitable combinations of substrates/impregnates. Some are [0232] non woven activated carbon filter media [0233] electret filter material [0234] coarse filter material [0235] combination of above mention filter materials.

[0236] Like for sulphur dioxide impregnation can be done by various methods using different impregnates like KOH and KMnO.sub.4. The impregnation process can be done with wet and dry methods. In the wet method the impregnant is in water solution which is sprayed onto the substrate. In the dry method the impregnant in powder form is aerosolised and then led through the substrate material.

[0237] The capacity of the gas filter is related to the mass of impregnant deposited on the substrate material. On the other hand, the deposited impregnant increases the pressure drop of the fibrous filter, or may reduce the adsorption capacity of other gaseous impurities in case of impregnation of the non-woven activated carbon substrate. Therefore the optimum amount of impregnant depends on the impregnant/substrate combination.

[0238] By using filter bags 15 with dimension 592*592*592 mm one filter unit with 10 bags would have 7 m.sup.2 filter surface. With ten 500*500 mm.sup.2 electrodes 14 covered on both sides with TiO.sup.2 in each filter bag 15 each filter unit would have 5 m.sup.2 TiO.sub.2 covered surface.

[0239] FIG. 14 shows a filter bag unit 26 without the charging unit 10. In this embodiment the corona brushes 17 are protected by a protective grid 38 in order to avoid electric shocks of maintenance personnel. The complete housing of the charging unit 10 is advantageously grounded. High voltage is fed to the corona brushes 17 through high voltage sockets 37.

[0240] FIGS. 15 and 16 show a charging and filter unit, where several charging units 10 are combined as a wall to fit different sizes of ventilation ducts. Filter units 38 in form of corrugated filter media are positioned after the charging units including the corona brushes 17.

[0241] FIGS. 17 and 18 show a cross section of FIG. 16, where the air flow first meets the charging unit 10 having a protective grid 36. After the charging unit 10 in the air flow passes through a corrugated filter media 38. This media is advantageously charged with positive voltage electrodes 38 and in this case it is advantageous that the filter media 38 is at least partially conductive. The positive voltage connected to electrodes 34 varies based on material of the media but is typically in the range of 1 kV. The filter media 38 comprises advantageously two layers, namely a layer of particle filter media and of gas filter media. Further, the filter media closest to the charging unit 10 is advantageously electrically conductive either as such or combined to another layer having gas filtering properties.

[0242] FIG. 19 shows one connectable embodiment of the charging unit to form a construction shown in FIGS. 15 and 16 in accordance with the invention to form a charging wall from multiple charging units 10. This is enabled by connectors for grounding 39 and negative high voltage 40 on the sides of the charging units 10 for connecting charging units next, or opposite to 10. FIG. 20 shows connectors 41 for positive voltage contacted to electrodes 34. These connectors are used as well connecting charging units next to or opposite to 25 in to each other.

[0243] FIG. 21 shows mounting rails 42, 43 of the invention for mounting the filtering unit to a fixed structure e.g. in front of a ventilation duct. The rails 42 are fixed to the filter structure and rails 42 slide inside the fixed rails 42 in order to make it possible to adjust the vertical position of the filter wall.

[0244] In accordance with the invention the polarities of the corona brushes 17 and positive electrodes 34 may be reversed.

[0245] In accordance with FIGS. 22 and 23 the filter unit 47 is combined with a mobile phone 45 or other mobile telecommunications device. Preferably the unit is positioned on the back side of the phone such that it does not block the camera optics 46. The inlet of the airflow 6 is on the back side of the phone 45 and the outlet preferably arranged such that it directs the air flow 6 to the face of the user. The device includes a fan 51 for producing the air flow and a high voltage unit 50 for charging the incoming air and particles preferably with help of corona brushes 17. In addition the filter comprises electrically conductive electrodes 14 covered with TiO.sub.2 and preferably connected to opposite high voltage than the corona elements, preferably corona brushes 17. In addition the filter unit 47 comprises UV-light sources 16, typically LED's with corresponding transformer 49. If the voltage of the phone is suitable for the LED's the transformer may be omitted. The filter unit may also include a removable particle filter 48 and include other conductive material for filtering particle and gas contaminants. The filter unit 48 may be removable aftermarket unit or OEM part of the phone like filter phone. In addition, the unit 48 may be disposable or reusable.

[0246] Additional monitoring device 58 consists of carbon dioxide sensor 57 and/or particle sensor 56. The device is connected directly to filter units pin out 54 connector and has itself a pin 55 for further connection.

[0247] FIG. 24 shows a perspective view of an embodiment of the invention where the electrodes 14 of the electrode unit are formed of transparent, electrically conductive film like plastic material. This plastic material is typically fixed by glue to support bars 52. Advantageously these plastic electrodes are connected to high voltage with opposite polarity than the high voltage of the charger unit. UV-leds 16 are positioned on both sides of the electrodes 14 to the support bars 52 and electrically connected with conductors 23 to supply voltage.

[0248] FIG. 25 shows in more detail positioning of the LEDs inside the support bars 52, in this case support bars 52 of U-profile.

[0249] FIG. 26 shows a schematic presentation of the invention, where the TiO.sub.2 coating is placed outside the filter bags with UV-light sources 17 and FIG. 27 shows a practical embodiment of FIG. 26.

[0250] In FIG. 28 is shown how a mobile phone 45 may be connected to the air filter 47 in accordance with the invention. Both the mobile phone 71 and the air filter 47 include a magnetic elements 71 glued (or otherwise attached) to the mobile phone 71 and the air filter 47. The magnetic elements 71 attach to each other by a magnetic force, either in position shown in figures ore they can be attached e.g. by turning one of the elements, e.g. mobile phone 45 by 90 degrees.

[0251] In FIG. 29 a filter unit 47 with a high voltage element 19 is shown in more detail. The filter unit 47 includes a filter cover 60, which may pass ultraviolet light, especially UV-A wavelengths. On a plastic sheet 60 beneath the cover 60 is positioned a plastic sheet 61 with a dot matrix printing to spread UV-light evenly to whole sheet. Below that there is a thin paper 62 and below that lid of filter material 64 and naturally below that the folded filter material 64. The main unit 47 includes the necessary electrical connections to the filter case 48.

[0252] FIG. 30 shows a filter unit 47 in accordance with the invention combined with a mobile phone 45. In the sectioned portion the filter material 64 is visible.

[0253] FIG. 31 shows another cross sectioned view of the air filter in accordance with the invention. Here in more detail can be seen a micro USB-port for charging the battery 72 of the filter unit. From the USB-A-port 67 the battery 72 may be used for charging other devices like the mobile phone 45 or other devices. The air filter 47 includes also a led indicator 69 for indicating the status of the air filter 47. The status may be for example on/off/charging. The air is taken in to the air filter 47 through intake grill 73 and output filtered through an exhaust hole 66. The air filter 47 includes also UV-A-LED's 16 on the side of the removable filter case 48 in order to create a photocatalytic effect with the filter material 64 including TiO.sub.2 or some other photocatalytic material. UV-light may enter the filter also trough the transparent filter cover 60. The photocatalytic material may be positioned also on some layer close to the filter 64 like on layers 61, 62 or 63. The material of the filter 64 is electrically conductive in some preferred embodiments of the invention in order to make the filter material 64 an electrode.

[0254] FIG. 32 shows an air filter 47 similar to air filter of FIG. 29 but without the high voltage unit 19 and corona brushes 17.

[0255] FIGS. 33 and 34 show the air flow through an air filter 47 in accordance with the invention. The unpurified air is entering the device 47 through the intake grill 73, then going through the filter unit/case 48. The air flow is created by the fan 51 (FIG. 31) by creating under pressure to the intake chamber 75 and outputting the purified air by the fan 51 to output chamber 76 and further through the exhaust hole 66 for the user. The exhaust hole may have an adjustable slider 74 for adjusting the direction and distribution of the air flow 66. The slider may also control the charging operation of the battery 72.

[0256] In FIG. 35 is presented in more detail the removable particle filter casing 48. Filter casing bottom 77 and sides 78 are from electrically conductive material. This conductive material 77, 78 is connected electrically to earth or other voltage different to the voltage of the high voltage unit 19. Preferably the polarities of the voltages of the high voltage 19 and the electrodes 77, 78 are different. Filter materials 64 are coated with TiO.sub.2, Ag or similar Nano photocatalyst. Filter casing 48 is from UVA penetrable plastic sheet having uniform distribution of UV-A led light. Therefore the light 16 may illuminate both the filter casing 48 and the cover 60 of the filter unit 48 for causing the photocatalytic reaction also to the cover part 60, when it is covered with photocatalytic material like TiO.sub.2. Similar sheet 63 is above filter casing 48 and between plastic sheets there is paper 62 to separate UV-LED light illumination to both sides. The paper 62 can be reflective in order to further enhance photocatalytic reaction. The paper layer 62 may have a pattern to be projected on the cover part of the filter structure 47. Casing structures 77, 78, 63, 61 and 60 can be also coated with Nano catalyst like TiO.sub.2. Negative ions can be discharged from carbon fibres 79 preferably with corona brushes 17 inside or in front of filter casing in order to accelerate photocatalytic reaction. Naturally, these fibers 79 are electrically isolated from the casing structures 77, 78, 63 and 60.

[0257] In summary the top layers of the filter casing 48 are the following from top to bottom: [0258] 61: Cover, UV-A penetrable sheet. Can be coated with TiO2 or similar. This is the unit cover also. Even surface or with luminous distribution pattern. [0259] 62: Thin paper sheet for dividing LED-illumination. [0260] 63: Filter material cover, UV-penetrable plastic and nanocoated with TiO2 or equivalent

[0261] UV-LEDs SMD type 16 assembled on printed circuit board (PCB) in the side of filter unit, illuminates both sheets 61 and 63. The LED's 16 may be on both sides of the structure 48. Carbon fibers 79 are for negative ion output.

[0262] Bottom 77 and side panels 78 are made from conductive material and either grounded or with reverse polarity than ion output 79.

[0263] In FIG. 36 are shown guiding pins 80 for filter material 64 assembly These pns 80 allow tight connection and automated assembly process. The pins 80 are connected to their counterparts in sheet 63.

[0264] In FIG. 37 is shown in more detail how the wave like filter material is assembled in the filter casing 48. This material 64 is typically with two layers, first with particle filtering media and the second with gas adsorbent material. The filter material 64 may comprise also additional layers. The filter material 64 is coated with TiO.sub.2 or equivalent material from both sides.

[0265] In FIG. 38 is shown the final construction.

[0266] When air purifiers (e.g. mobile communication devices in this invention) are equipped with CO.sub.2 sensors, carbon dioxide levels can adjust the speed of fan 51 automatically. These units are designated to be close enough users face for enabling clean breathing zone. The CO.sub.2 sensor can detect elevated CO.sub.2 level and fan 51 will operate faster. When CO.sub.2 level is low, air purifier goes to standby mode in order to save energy. The speed of the fan 51 may also be adjusted based on the flow resistance of the filter casing 48 such that when the flow resistance rises the speed of the fan 51 increases. The flow resistance may be determined e.g. by pressure or temperature measurement before the filter casing 48. Rising speed of motor or increased pressure or increased temperature before the filter 48 means that the filter flow resistance has increased. When the filter casing 48 is too full, e.g. the flow resistance has increased more than 30%, this situation may be indicated by a light or sound.

[0267] Instead of TiO.sub.2 materials like carbon-doped titanium dioxide (CTiO.sub.2), ZnO (https://www.hindawi.com/journals/ijp/2013/795060/) or Nanocomposite coating of TiO.sub.2 and Polytetrafluoroethylene (http://onlinelibrary.wiley.com/doi/10.1002/adma.201201037/abstract) could be used as photo catalytic material.

[0268] The light sources 16 are advantageously LEDs typically with the following properties:

Power/led: 0.06-1 W

[0269] Wavelength in following ranges: 300-420 nm

[0270] Some embodiments of the invention are defined in the following paragraphs:

[0271] Paragraph 1. An electrostatic filter construction (2) including [0272] a charging unit (10), which charges the particles to be filtered into a first electric potential and arranged in the filter construction (2) in the path of the air flow before filter elements (15), [0273] electrically conducting electrodes (14, 25) connected to a second electric potential different to the potential of the charged particles and set substantially parallel to the direction of the airflow, and [0274] filter elements (15) positioned after the charging unit (10) in the path of the air flow,
characterized in that [0275] each filter element (15) has at least one designated UV-light source (6) and an element (14, 31) of photo catalytic material like TiO.sub.2.

[0276] Paragraph 2. An electrostatic filter construction (2) according to Paragraph 1, characterized in that it is positioned in air ducts or ventilation channels and the filter elements (15) are bag shaped.

[0277] Paragraph 3. An electrostatic filter construction (2) according to Paragraph 1 or 2, characterized in that the bag shaped filter elements (15) are positioned around the electrodes (14), and inside the bag shaped filter elements (15) are positioned UV-light sources (16) and photo catalytic material like TiO.sub.2.

[0278] Paragraph 4. An electrostatic filter construction (2) according to Paragraph 1 or 2, characterized in that the at least one designated UV-light source (6) and an element (31) photo catalytic material like TiO.sub.2 are positioned in front of the bag shaped filter element (15) in the path of the air flow (FIG. 10).

[0279] Paragraph 5. An electrostatic filter construction (2) according to Paragraphs 1-4, characterized in that the electrodes (14) are covered with photo catalytic material like TiO.sub.2 or equivalent photo catalytic material and connected electrically to ground potential or to opposite polarity than high voltage unit for corona discharge before it.

[0280] Paragraph 6. An electrostatic filter construction (2) according to any previous Paragraph, characterized in that the charging unit (10) comprises corona strips (20) including brush like extensions (17) directed against the air flow.

[0281] Paragraph 7. An electrostatic filter construction (2) according to any of the above Paragraphs, characterized in that the corona strips (20) are connected to negative high voltage.

[0282] Paragraph 8. An electrostatic filter construction (2) according to any of the above Paragraphs, characterized in that the bag shaped filter (15) comprises a layer of particle filter media (27) and of gas filter media (28).

[0283] Paragraph 9. An electrostatic filter construction (2) according to any of the above Paragraphs, characterized in that the bag shaped filter (15) comprises multiple subfilters (30).

[0284] Paragraph 10. An electrostatic filter construction (2) according to any of the above Paragraphs, characterized in that the bag shaped filters (15) are disposable.

[0285] Paragraph 11. An electrostatic filter construction (2) according to any of the above Paragraphs, characterized in that inside the bag shaped filters (15) are electrodes (34) connected to a voltage, the polarity of which is opposite to the voltage of the charging unit (10).

[0286] Paragraph 12. An electrostatic filter construction (2) according to any of the above Paragraphs, characterized in that the bag shaped filters (27) are made of electrically conducting material.

[0287] Paragraph 13. An electrostatic filter construction (2) according to any of the above Paragraphs, characterized in that one side of the bag shaped filters (27) is covered with TiO.sub.2 and this side is exposed to UV-light.

[0288] Paragraph 14. An electrostatic filter construction (2) according to any of the above Paragraphs, characterized in that the filter construction (2) is connected to a mobile communication device.

[0289] Paragraph 15. An electrostatic filter construction (2) according to Paragraph 13, characterized in that the filter construction is an integral part of the mobile communication device.

[0290] Paragraph 16. An air cleaning method, where an air flow is created and which method comprises steps for [0291] charging the particles to be filtered into a first electric potential before they enter filter elements (15), [0292] attracting the charged particles by electrically conducting electrodes (14, 31) connected to a second electric potential different to the potential of the charged particles and set substantially parallel to the direction of the airflow, and [0293] guiding the charged air through filter elements (15) positioned after the charging unit (10) in the path of the air flow.
characterized in that [0294] directing UV-light in or close to each bag shaped filter element (15) and placing the photo catalytic material like TiO.sub.2 close to the UV-light.

[0295] Paragraph 17. An air cleaning method according to Paragraph 16, characterized in that it is used for ducts or ventilation channels and the filter elements (15) are bag shaped.

[0296] Paragraph 18. An air cleaning method according to Paragraph 16 or 17, characterized in positioning the bag shaped filter elements (15) around the electrodes (14), and positioning inside the bag shaped filter elements (15) UV-light sources (16) and photo catalytic material like TiO.sub.2.

[0297] Paragraph 19. An air cleaning method according to Paragraph 16 or 17, characterized in positioning the at least one designated UV-light source (6) and an element (31) photo catalytic material like TiO.sub.2 in front of the bag shaped filter element (15) in the path of the air flow (FIG. 10).

[0298] Paragraph 20. An air cleaning method according to Paragraph 16-19, characterized in covering the electrodes (14) with photo catalytic material like TiO.sub.2 or equivalent photo catalytic material and connecting them electrically to ground potential.

[0299] Paragraph 21. An air cleaning method according to any previous method Paragraph, characterized in that the charging unit (10) comprises corona strips (20) including brush like extensions (17) directed against the air flow.

[0300] Paragraph 22. An air cleaning method according to any previous method Paragraph, characterized in that the corona strips (20) are connected to negative high voltage.

[0301] Paragraph 23. An air cleaning method according to any previous method Paragraph, characterized in that the bag shaped filter (15) comprises a layer of particle filter media (27) and of gas filter media (28).

[0302] Paragraph 24. An air cleaning method according to any previous method Paragraph, characterized in that the bag shaped filter (15) comprises multiple subfilters (30).

[0303] Paragraph 25. An air cleaning method according to any previous method Paragraph, characterized in that the bag shaped filters (15) are disposable.

[0304] Paragraph 26. An air cleaning method according to any of the above method Paragraphs, characterized in that inside the bag shaped filters (15) are electrodes (34) connected to a voltage opposite to the voltage of the charging unit (10, 25).

[0305] Paragraph 27. An air cleaning method according to any of the above method Paragraphs, characterized in that the bag shaped filters (27) are made of electrically conducting material.

[0306] Paragraph 28. An air cleaning method according to any of the above method Paragraphs characterized in that one side of the bag shaped filters (27) is covered with TiO.sub.2 and this side is exposed to UV-light.

[0307] Paragraph 29. An air cleaning method according to any of the above Paragraphs, characterized in that the filter construction (2) is connected to a mobile communication device.

[0308] Paragraph 30 An air cleaning method according to Paragraph 27, characterized in that the filter construction (2) is an integral part of the mobile communication device.

[0309] Paragraph 31. A mobile filter unit including [0310] a mobile communication device (45),
characterized in that it further includes [0311] a filter unit (47) connected to the mobile communication device (45) including [0312] a fan (51) for generating an air flow (6) from behind of the mobile communication device (45), [0313] high voltage unit (50, 17) for charging the air flow (6) and its particles, [0314] TiO.sub.2-covered electrodes (16) in the air flow (6) connected to opposite polarity than the high voltage unit (50, 17), [0315] UV-LEDs (16) illuminating the electrodes (16), and [0316] outlet (53) for the air flow directed in direction of user of the mobile communication device (45).

[0317] Paragraph 32. A mobile filter unit in accordance with paragraph 31, characterized in that the electrodes (16) are as filter consumable filter unit and the electrodes are from aluminium, plastic or other suitable conductive materials and are forming a low pressure drop form like honeycomb, mesh, fins, pleated etc.

[0318] Paragraph 33. A mobile filter unit in accordance with paragraph 31 or 32, characterized in that it includes a removable particle filter.