Abstract:
A photo-catalyst air cleaner includes at least one light source, a photo-catalyst filter and a first water supply. The photo-catalyst filter includes a hydrophilic substrate with a layer formed on a surface of the substrate exposed to light from the at least one light source. The water supply is configured for supplying water for absorption by the substrate, thereby humidifying surfaces of the photo-catalyst filter.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is related to the following commonly-assigned copending applications: Ser. No. 12/240,422, entitled “AIR CLEANER” (attorney docket number US 18918). Disclosure of the above-identified application is incorporated herein by reference. 
     
    
     BACKGROUND 
       [0002]    1. Technical Field 
         [0003]    The present invention generally relates to air cleaning, and particularly to a photo-catalyst air cleaner providing self-contained humidifying capability. 
         [0004]    2. Description of Related Art 
         [0005]    In recent years, photo-catalyst air cleaners have become widely used. Photo-catalysts, for example titanium oxide (TiO 2 ), are excited by photo-energy to sterilize microbes and decompose pollutants. In operation, the photo-catalysts is exposed to UV light, and electron-hole pairs are excited from within the photo-catalysts to the surface thereof, to react with the water vapor, forming hydroxyl radical (.OH) having higher oxidative ability. Pollutants are easily adsorbed by the water vapor on the surface. The photo-catalysts, when excited, kills microbes and decomposes organic pollutants into water vapor (H 2 O) and carbon dioxide (CO 2 ). However, performance of the cleaners is dependent on the amount of water vapor present in the environment. In a dry setting, air cleaning performance is reduced. 
         [0006]    Therefore, what is needed is a photo-catalyst air cleaner which can overcome the described limitations. 
       SUMMARY 
       [0007]    A photo-catalyst air cleaner includes at least one light source, a photo-catalyst filter, and a water supply. The photo-catalyst filter includes a hydrophilic substrate with a layer on a surface thereof, exposed to light from the at least one light source. The water supply supplies water for absorption by the substrate, thereby humidifying surfaces of the photo-catalyst filter. 
         [0008]    Other advantages and novel features of the present photo-catalyst air cleaner will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings, in which: 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]    Many aspects of the present photo-catalyst air cleaner can be better understood with reference to the following drawings. The components in the drawings are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of the present illumination device. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views. 
           [0010]      FIG. 1  is a schematic view of a photo-catalyst air cleaner, in accordance with a first embodiment. 
           [0011]      FIG. 2  is an enlarged partial cross-section of a photo-catalyst filter of  FIG. 1 . 
           [0012]      FIG. 3  is a schematic view of a photo-catalyst air cleaner, in accordance with a second embodiment. 
           [0013]      FIG. 4  is a schematic view of a photo-catalyst air cleaner, in accordance with a third embodiment. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0014]    Referring to  FIG. 1 , a photo-catalyst air cleaner  10 , in accordance with a first embodiment, comprises a photo-catalyst filter  11 , a light source  12 , and a water supply  13 . 
         [0015]    Referring to  FIGS.1-2 , the photo-catalyst filter  11  comprises a substrate  112  and a photo-catalyst layer  114 . The substrate  112  has a surface  1120  on which the photo-catalyst layer  114  is coated by sintering, making contact with air to decompose pollutants and sterilize airborne microbes. The substrate  112  has a porous structure, including a plurality of holes  1122  defined on the surface  1120  thereof. The holes  1122  may interpenetrate or be separate from each other. The photo-catalyst layer  114  can be further coated on inner walls of the substrate  112  in the holes  1122  thereof, increasing surface area of the photo-catalyst layer  114  to improve decomposition and sterilization capability of the photo-catalyst layer  114 . Preferably, the substrate  112  is alumina ceramic with high hydroscopicity. The photo-catalyst layer  114  is made of photo-catalyst material, such as tin oxide (SnO 2 ), zinc oxide (ZnO), tungsten oxide (WO 3 ), iron oxide (Fe 2 O 3 ), SeTiO 3 , cadmium selenide (CdSe), KTaO 3 , cadmium sulfide (CdS) or niobium oxide (Nb 2 O 5 ). Preferably, the photo-catalyst layer  114  is nanometer sized titanium dioxide (TiO 2 ) with high fluid permeability. 
         [0016]    The light source  12  can be an ultra-violet (UV) lamp, such as a UV fluorescent lamp, and preferably a UV light-emitting diode. Additionally, the number of light sources  12  can be more than one. 
         [0017]    The water supply  13  is a container with water with at least one hole  131  for refilling water. 
         [0018]    In operation, one end of the photo-catalyst filter  11  is immersed in the water of the container, and a water film is formed on the surface  1140  thereof (including the substrate  112  and the photo-catalyst layer  114 ). The photo-catalyst layer  114  is exposed to light from the UV light emitting diode, and electron-hole pairs are excited from within the photo-catalyst layer  114  to the surface  1140  thereof, to react with the water film, forming hydroxyl radical (.OH) having higher oxidative ability. Pollutants are easily adsorbed by the water film on the surface  1140 . The photo-catalyst layer  114 , when excited, kills microbes and decomposes organic pollutants into water vapor (H 2 O) and carbon dioxide (CO 2 ). 
         [0019]    Water from the water supply  13  can be adsorbed by the surface  1140  to form hydroxyl radicals, ensuring the quality of decomposition and sterilization capability of the photo-catalyst layer  114 . 
         [0020]      FIG. 3  shows a photo-catalyst air cleaner  20 , in accordance with a second embodiment, differing from photo-catalyst air cleaner  10  of the first embodiment only in the presence of two water supplies, a first water supply  23  cooperating with a second water supply, providing water to form a water film on a surface  2140  of a photo-catalyst layer  214  to form hydroxyl radicals. 
         [0021]    The second water supply  24  is arranged opposite the first water supply  23  at another end of the photo-catalyst filter  21 , and includes a number of water outlets  240 A dispensing water onto the photo-catalyst filter  21 . Each of the water outlets  240 A is coupled to a water valve  240 B, by which the amount of water is controlled. The photo-catalyst filter  21  absorbs water from both the first and second water supplies  23 ,  24 . It is to be understood that the second water supply  24  can also dispense water on two lateral sides of the photo-catalyst filter  21 , if greater surface coverage is desired. 
         [0022]      FIG. 4  shows another photo-catalyst air cleaner  30 , in accordance with a third embodiment, differing from photo-catalyst air cleaner  20  of the second embodiment only in the presence of a capillary suction device  35  with high hydroscopicity, retrieving water from first and second water supplies  33 ,  34 . 
         [0023]    The capillary suction device  35  surrounds the photo-catalyst filter  31 , and is in contact with the photo-catalyst filter  31 . Water of the first and second supplies  33 ,  34  is absorbed by and diffused within the capillary suction device  35  quickly and uniformly. Photo-catalyst filter  31  absorbs the water via the capillary suction device  35 , to form a water film on a surface  3140  of the photo-catalyst layer  314 . The capillary suction device  35  allows simpler water distribution system if needed (the photo-catalyst air cleaner  30  uses only one water outlet  340 A), and water film formed on the surface  3140  remains uniform and sufficient. 
         [0024]    The capillary suction device  35  is flannelet of high hydroscopicity, adsorbent cotton, such as polyvinyl alcohol (PVA) adsorbent cotton or other fiber or fabric with high hydroscopicity. 
         [0025]    It is believed that the present invention and its advantages will be understood from the foregoing description, and it will be apparent that various changes may be made thereto without departing from the spirit and scope of the invention or sacrificing all of its material advantages, the examples hereinbefore described merely being preferred or exemplary embodiments of the invention.